WO2017099016A1

WO2017099016A1 - Layered film

Info

Publication number: WO2017099016A1
Application number: PCT/JP2016/085904
Authority: WO
Inventors: 松居久登; 合田亘
Original assignee: 東レ株式会社
Priority date: 2015-12-08
Filing date: 2016-12-02
Publication date: 2017-06-15
Also published as: TWI706862B; CN108136745B; CN108136745A; JPWO2017099016A1; KR20180090982A; JP6780636B2; KR102655116B1; TW201733807A

Abstract

The present invention provides a high-transparency layered thin film in which UV-ray-precipitated degradation is suppressed, and the quality and color tone of a display are stably demonstrated over prolonged periods of time, without any incidence of bleed-out when the thin film is produced. A film in which a layer principally comprising a thermoplastic resin A (layer A) and a layer principally comprising a thermoplastic resin B that is different from the thermoplastic resin A (layer B) are layered in five or more layers, wherein the light transmittance at a wavelength of 410 nm is 60% or less, and the light transmittance at a wavelength of 440 nm is 80% or more.

Description

Laminated film

The present invention relates to a laminated film excellent in ultraviolet cut property and visible light transmittance.

Thermoplastic resin films, especially biaxially stretched polyester films, have excellent properties such as mechanical properties, electrical properties, dimensional stability, transparency, and chemical resistance. Are widely used as substrate films. In recent years, in the flat panel display, touch panel field, and in-vehicle panel display applications, the trend toward cost reduction and thinning / miniaturization / flexibility of displays is rapidly progressing, and the demand for various thin film optical films is increasing. .

Examples of the optical film mounted on the display include a polarizer protective film, a transparent conductive film, and a retardation film for use in liquid crystal displays. Films used for these applications are required to have UV-cutting properties in order to prevent deterioration of liquid crystal molecules and polarizers (PVA) in the polarizing plate due to UV rays entering from the outside and UV rays contained in backlight light. In general, a technique of adding an ultraviolet absorber is used to impart ultraviolet cut property to a film (Patent Document 1). However, when the ultraviolet cut is achieved by the method of adding an ultraviolet absorber, a bleed-out phenomenon occurs in the vicinity of the die or in the vacuum vent at the time of film formation depending on the type and amount of the ultraviolet absorber. For this reason, there arises a problem of deteriorating the quality of the film itself, such as contamination of the film forming process, resulting in a defect in the film, and a substantial decrease in the UV absorber addition concentration resulting in a decrease in cutting performance. In particular, when the same performance as the current optical film is demonstrated as a thin film optical film, the absorption performance is expressed by the product of the film thickness and the addition concentration, so it is impossible to avoid the addition of a high concentration of UV absorber. Contamination of the film forming apparatus, and deterioration of the quality due to the deposition of the absorbent on the film surface after a severe reliability test become remarkable.

In addition, in the case of a display that is displayed outdoors such as in-vehicle display applications or digital signage, it is required to more strongly cut ultraviolet rays in the wavelength range of 300 nm to 380 nm. When using a general UV absorber specializing in cutting performance in a wavelength band of 380 nm or less, excessive addition of the UV absorber is excessive in order to strongly cut light in the vicinity of a wavelength of 380 nm, which is not good at UV absorbers. However, in the case of a thin film, problems such as whitening due to excessive addition of the absorbent and deterioration of the quality due to precipitation of the absorbent on the film surface after a severe reliability test occur. In particular, in the case of a single film configuration or a low number of layers, the mechanism for preventing the precipitation of the absorbent becomes insufficient, and the problem of deterioration in the reliability test becomes remarkable. Since the additive concentration of the absorbent can be reduced by increasing the thickness, the above problem can be solved, but the problem arises that the thickness of the image display device increases against the demand for downsizing and thinning of the market. .

In order to cut a light beam having a wavelength in the vicinity of 380 nm, a method using a dye having a maximum absorption wavelength on the longer wavelength side than 380 nm can be mentioned. However, since the dye absorbs a wide range of visible light depending on the type and causes undesired coloration on the film itself, it deteriorates the visibility when mounted on a display. It is necessary to sharply cut the light beam in the wavelength range up to 430 nm (Patent Documents 2 to 4). As described in Patent Document 4, there is a method using a fluorescent brightening agent as an absorbent as an object of preventing coloring when a light beam having a wavelength longer than 430 nm is cut. However, when used as a display, ultraviolet rays are irradiated. In this case, the film itself emits blue fluorescence, which causes a problem that the quality of display is significantly impaired.

In addition, the film mounted on the display is required to maintain not only the optical quality such as hue but also the mechanical properties such as thickness in the reliability test. When the film shrinks due to heat treatment and causes an increase in thickness, the absorption performance of ultraviolet absorbers and pigments increases, causing a problem that undesired coloring occurs.

JP 2013-210598 A JP 2010-132848 A JP 2014-115524 A JP 2008-238586 A

Therefore, in the present invention, the above-mentioned drawbacks are eliminated, and there is no bleed out during film formation, and it is possible to maintain optical performance such as hue and white turbidity (haze) even in a long-term reliability test. It aims at providing the highly transparent laminated film excellent in the rate.

The present invention has the following configuration. That is,
It is a film in which five or more layers alternately composed of a layer mainly composed of a thermoplastic resin A (A layer) and a layer mainly composed of a thermoplastic resin B different from the thermoplastic resin A (B layer), The laminated film is characterized in that the light transmittance at a wavelength of 410 nm is 60% or less and the light transmittance at a wavelength of 440 nm is 80% or more.

The laminated film of the present invention maintains a color tone for a long period of time when it is mounted on an image display device without bleeding out various additives including an ultraviolet absorber during film formation by using a laminated structure. There is an effect that an image can be displayed with high quality.

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

The laminated film of the present invention has five or more layers alternately composed of a layer mainly composed of the thermoplastic resin A (A layer) and a layer mainly composed of the thermoplastic resin B different from the thermoplastic resin A (B layer). It is a laminated film, and it is necessary that the light transmittance at a wavelength of 410 nm is 60% or less and the light transmittance at a wavelength of 440 nm is 80% or more.

Examples of the thermoplastic resin in the present invention include polyethylene, polypropylene, poly (1-butene), poly (4-methylpentene), polyisobutylene, polyisoprene, polybutadiene, polyvinylcyclohexane, polystyrene, and poly (α-methylstyrene). , Polyolefin resins represented by 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 / acryl methacrylate copolymer, ethylene / norbornene copolymer, Resin / vinyl acetate copolymer, propylene / butadiene copolymer, isobutylene / isoprene copolymer, vinyl monomer copolymer resins such as vinyl chloride / vinyl acetate copolymer, polyacrylate, polymethacrylate, polymethyl methacrylate, polyacrylamide, polyacrylonitrile, etc. Acrylic resins typified by polyethylene, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyester resins typified by polyethylene-2,6-naphthalate, etc., polyethers typified by polyethylene oxide, polypropylene oxide, polyacrylene glycol Resin, diacetylcellulose, triacetylcellulose, propionylcellulose, butyrylcellulose, Cetylpropionyl cellulose, cellulose ester resin typified by nitrocellulose, biodegradable polymer typified by polylactic acid, polybutyl succinate, etc., 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, trifluorinated ethylene resin, trifluorinated ethylene chloride Resin, tetrafluoroethylene-6-propylene copolymer, polyvinylidene fluoride, and the like can be used.

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

The thermoplastic resin B is not the same thermoplastic resin as the thermoplastic resin A but a resin having a different refractive index. In the case of using a light beam cut by reflection, which will be described later, the wavelength of the light beam to be reflected is determined as one based on the layer thickness of the laminated resin and the refractive index difference between two different thermoplastic resins. For this reason, when the same refractive index is used, light reflection at the thermoplastic resin interface does not occur. In order to reflect light of a specific wavelength, two types of parameters, that is, the resin layer thickness and the refractive index difference should be controlled. Therefore, it is difficult to determine only the refractive index difference, The difference in refractive index between the plastic resin A and the thermoplastic resin B is preferably 0.01 or more, more preferably 0.03 or more, and still more preferably 0.05 or more. Moreover, it is preferable that these different thermoplastic resins A and B have different thermal properties in addition to different refractive indexes. Different thermal properties refer to those showing different melting points and glass transition temperatures in differential scanning calorimetry (DSC). When the melting point and the glass transition temperature are different, the orientation state of each layer can be highly controlled in the step of stretching and heat treating the laminated film. Since the orientation state can be controlled to a high degree, it becomes possible to control the refractive index in the in-plane and perpendicular directions of each thermoplastic resin layer and to control the wavelength of the reflected light. In particular, the glass transition temperature and the melting point that affect the orientation state of the resin in the stretching step are preferably different by 0.1 ° C. or more between the thermoplastic resin A and the thermoplastic resin B. Among the thermoplastic resins described above, it is preferable that at least one of the thermoplastic resin A and the thermoplastic resin B is made of a polyester resin from the viewpoint of strength, heat resistance, transparency, and versatility. Furthermore, it is most preferable that both the thermoplastic resin A and the thermoplastic resin B are polyester resins from the viewpoints of adhesion and lamination. Below, the aspect of the polyester-type resin which is a preferable film base material is described.

The polyester in the present invention is a condensation polymer obtained by polymerization from a monomer mainly composed of an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid and a diol. As an industrial production method of polyester, as is well known, transesterification (transesterification) or direct esterification (direct polymerization) 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′- Examples thereof include diphenyl dicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid, and 4,4′-diphenyl sulfone dicarboxylic acid. Examples of the aliphatic dicarboxylic acid include adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, 1,4-cyclohexanedicarboxylic acid and ester derivatives thereof. Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid exhibiting a high refractive index are preferably used. One of these dicarboxylic acid components may be used, or two or more dicarboxylic acid components may be used in combination.

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

Further, the polyester resin includes, for example, polyethylene terephthalate and its copolymer, polyethylene naphthalate and its copolymer, polybutylene terephthalate and its copolymer, polybutylene naphthalate and its copolymer, and polyhexamethylene. It is also possible to use terephthalate and its copolymer, polyhexamethylene naphthalate and its copolymer, and the like. At this time, as the copolymerization component, it is preferable that at least one of the dicarboxylic acid component and the diol component is copolymerized. *

In the present invention, alternately laminating means that the A layers mainly composed of the thermoplastic resin A and the B layers mainly composed of the thermoplastic resin B are laminated in a regular arrangement in the thickness direction. , A (BA) n (n is a natural number) refers to a state in which a resin is laminated according to a regular arrangement. When forming a laminated film of A (BA) n (n is a natural number), a plurality of resins of thermoplastic resin A and thermoplastic resin B are sent out from different flow paths using two or more extruders. A multi-manifold type feed block, a static mixer, or the like that is a laminating apparatus can be used. In particular, in order to efficiently obtain the configuration of the present invention, a method using a feed block having fine slits is preferable for realizing highly accurate lamination. When forming a laminated body using a slit-type feed block, the thickness and distribution of each layer can be achieved by changing the length and width of the slit to incline the pressure loss. The length of the slit refers to the length of the comb-tooth portion that forms a flow path for alternately flowing the A layer and the B layer in the slit plate.

The thermoplastic resin A in the present invention is preferably a thermoplastic resin exhibiting crystallinity from the point of being located in the outermost layer of the laminated film as described above. In this case, it is preferable because a laminated film can be obtained in the same manner as the film forming step of a single film made of a thermoplastic resin exhibiting crystallinity. When the thermoplastic resin A is made of an amorphous resin, for example, when a biaxially stretched film is obtained in the same manner as a general sequential biaxially stretched film described later, it is manufactured by adhesion to a production facility such as a roll or a clip. Problems such as film defects and deterioration of surface properties may occur.

From the above, it is preferable to use polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate, which are crystalline polyesters, as the thermoplastic resin A. Among them, it is preferable to use polyethylene terephthalate or polyethylene naphthalate from the viewpoint of easily realizing a laminated structure with high accuracy in the stretching process. On the other hand, the thermoplastic resin B is preferably a polyester-based resin including the same basic skeleton as the thermoplastic resin A from the viewpoint of adhesion and lamination with the thermoplastic resin A. Here, the basic skeleton is a repeating unit constituting the resin. In the case of polyethylene terephthalate, ethylene terephthalate is used, and in the case of polyethylene naphthalate, ethylene naphthalate is the basic skeleton. By having the same skeleton, the lamination accuracy is high, and delamination at the lamination interface is less likely to occur. In contrast to polyethylene terephthalate, polyethylene naphthalate tends to cause polymer delamination in the plane direction, but more easily causes delamination. Therefore, it is more preferable to use polyethylene terephthalate as a basic skeleton from the viewpoint of a laminated film.

When polyethylene terephthalate is used as the basic skeleton, the thermoplastic resin B different from the thermoplastic resin A includes a copolymer component that has a polyethylene terephthalate skeleton and does not constitute the basic skeleton so as not to be a main component. It is preferably designed or designed so that the amount of copolymerization component is different from the amount of copolymerization component contained in the thermoplastic resin A. Suitable copolymer components when polyethylene terephthalate is used as a basic skeleton include cyclohexanedimethanol, bisphenol A ethylene oxide, spiroglycol, isophthalic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, polyethylene glycol 2000, m-polyethylene glycol 1000, Examples thereof include m-polyethylene glycol 2000, m-polyethylene glycol 4000, m-polypropylene glycol 2000, bisphenylethylene glycol fluorene (BPEF), fumaric acid, acetoxybenzoic acid and the like. Of these, spiroglycol, isophthalic acid, and 2,6-naphthalenedicarboxylic acid are preferably copolymerized. When spiroglycol is copolymerized, the glass transition temperature difference from polyethylene terephthalate is small, so that overstretching is difficult during molding and delamination does not occur easily. Furthermore, isophthalic acid can greatly reduce crystallinity because the position of the functional group in the benzene ring is not linear, while it can exhibit a high refractive index as a whole because of its high planarity.

The number of layers in the laminated film of the present invention should be 5 or more. As will be described later, in order to achieve a specific wavelength cut in the present invention, it is preferable to add an ultraviolet absorber and / or a dye having a maximum wavelength that is the maximum in the visible light short wavelength region exceeding 380 nm and not exceeding 430 nm, By setting it as a laminated structure, precipitation to the surface of an additive can be suppressed. In particular, when the thermoplastic resin is crystalline, the crystalline layer forms a densely packed layer by folding the molecular structure, so that it can serve as a lid that suppresses the precipitation of various additives present inside. It is preferable because it plays a role. There is no upper limit to the number of layers, but as the number of layers increases, the manufacturing cost increases with the increase in the size of the manufacturing apparatus, and the handling properties deteriorate due to the increase in film thickness. In particular, increasing the thickness of the film increases retardation and is not preferable when used for display materials because it causes coloring of the film such as interference colors and rainbow spots. In reality, 1000 layers or less are suitable.

Retardation is generally calculated from the product of the maximum value of the refractive index difference between two orthogonal directions in the plane of the film and the film thickness. Since the refractive index cannot be measured, the retardation value calculated by an indirect method is used as retardation. Specifically, the value measured by the phase difference measuring device KOBRA series that measures retardation using an optical method of Oji Scientific Instruments Co., Ltd. is used. For example, consider the case where the optical film used for a display is used for a display equipped with a linearly polarized polarizing plate. When the retardation value is high and the orientation of the resin is not uniform within the laminated film surface, the polarization state varies in the surface due to the retardation, so interference color and rainbow unevenness when mounted on a liquid crystal display. This causes a problem that visibility is lowered. Therefore, in the present invention, when a crystalline thermoplastic resin that exhibits orientation by stretching or crystallization is included, it is preferable to reduce the film thickness as much as possible in order to reduce retardation. On the other hand, it is also preferable to design the orientation angle of the laminated film to be low by stretching it in a specific direction. Even when the retardation is relatively high by attaching the laminated film so that the optical axis of the transmitted light from the inside of the display and the orientation direction of the laminated film are the same or orthogonal when mounting the display. Since there is no variation in, there will be no problem of reduced visibility such as rainbow unevenness. When the orientation angle of the laminated film is lowered, the orientation angle in the width direction of the laminated film is preferably 10 ° or less, more preferably 7 ° or less, and further preferably 5 ° or less. When the orientation angle in the width direction of the laminated film exceeds 10 °, depending on the size of the display to be bonded, rainbow unevenness due to the orientation angle changing in the display surface is observed, and the polarization performance is It is not preferable because it is damaged. The orientation angle here is 0 ° in the film width direction.

The laminated film of the present invention is required to have a light transmittance of 60% or less at a wavelength of 410 nm. If the light transmittance of the laminated film is not 60% or less at 410 nm, when the laminated film of the present invention is used as a display application, the liquid crystal display may deteriorate the internal liquid crystal layer and the polarizer, and the organic EL display. In the display having the light emitting element, it is impossible to effectively prevent the light emitting layer from being altered or deteriorated. The light transmittance at a wavelength of 410 nm is preferably 40% or less, more preferably 30% or less, and still more preferably 20% or less. Although it is possible to protect the display contents from ultraviolet rays by setting the light transmittance at a wavelength of 410 nm to 60% or less, the light transmittance at a wavelength of 410 nm is reduced to 40% or less, more preferably to 20% or less. Thus, it is possible to prevent it for a longer period. On the other hand, when the light transmittance at a wavelength of 410 nm is more than 20% and not more than 60%, in addition to being able to protect the deterioration of the contents of the display compared to the conventional case, when light cut is achieved using reflection Therefore, it is possible to suppress the reflected hue caused by the light beam reflected on the viewer side, so that the black color when the display is not displayed can be made clearer.

It is more preferable that the laminated film of the present invention has a light transmittance of 20% or less in a wavelength range of 380 to 395 nm which is a visible light short wavelength region. Even if the light transmittance at a wavelength of 410 nm is low, if light in the wavelength range having energy stronger than that at a wavelength of 410 nm cannot be cut, there is a high possibility that light deterioration will be promoted. More preferably, it is 15% or less, and more preferably 10%.

In the laminated film of the present invention, it is more preferable that the maximum value of light transmittance in the ultraviolet region with a wavelength of 300 nm to 380 nm is 10% or less. The UV region with a wavelength of 300 nm to 380 nm is a wavelength region that has a strong light energy and greatly contributes to the degradation of important parts of the image display such as the polarizer, liquid crystal, and light emitting element inside the display. It is desirable. For example, a polarizer used in a liquid crystal image display device has a function of transmitting light having only a specific vibration direction, and is a polyvinyl alcohol (PVA) film dyed with iodine or a dichroic dye. Is the most used. This polarizer is made of an organic material, and particularly deteriorates when it receives ultraviolet rays having a high energy in the wavelength range of 280 to 380 nm. Therefore, the ultraviolet rays in this region are shielded before reaching the polarizers. It is possible to prevent the deterioration of the polarizer or the deterioration of the liquid crystal molecules. From this, the maximum value of the light transmittance at a wavelength of 300 nm to 380 nm is 5% or less, more preferably 2% or less.

The laminated film of the present invention is required to have a light transmittance of 80% or more at a wavelength of 440 nm. When the light transmittance at a wavelength of 440 nm is less than 80%, the light in the visible light short wavelength region is cut, so that the laminated film itself exhibits a strong yellow color and cannot exhibit excellent transparency. Moreover, in the display use using a blue light emitting element, the light ray derived from a blue light emitting element will be cut, and it will lead to the color tone deterioration in the case of an image display. The light transmittance at a wavelength of 440 nm is preferably 85% or more, more preferably 90% or more.

The laminated film of the present invention preferably has an average light reflectance at a wavelength of 380 to 410 nm of 20% or more. It is possible to reflect light of a specific wavelength according to the thicknesses of the alternately laminated resin layers and the refractive index difference between two different types of resins. Also, by changing the thickness distribution of the laminated layer, the reflected wavelength band can be expanded and contracted, the light reflectance can be improved, and the thickness can be freely shifted by changing the thickness while keeping the lamination ratio constant. Can do. At this time, it is possible to design the cut edge of the reflection band sharply or gently by controlling the thickness distribution of the laminated layer. When designing the cut edge of the reflection band to be sharp, it can achieve a sharp cut that is superior to the addition of general UV absorbers, dyes and pigments, and prevents unwanted light cuts. It can be preferably used for materials that require selective wavelength cut. The average light reflectance is more preferably 25% or more, and further preferably 30% or more.

Since the reflection wavelength depends on the layer thickness, it is affected by a slight change in film thickness in units of 0.1 μm and varies sensitively. Therefore, when it is designed so that the long wavelength end of the reflection band is located in the vicinity of 440 nm, there is a possibility that the wavelength region which is not originally desired is cut due to a slight increase in thickness. In consideration of the risk of fluctuations in the reflection wavelength range, the reflection wavelength range is designed to be not less than 300 nm and not more than 410 nm, and light in the wavelength range of 380 to 430 nm is maximized in the visible light short wavelength range of 430 nm to 430 nm, which will be described later. It is a more preferable embodiment to cut in combination with absorption by a dye having a maximum wavelength.

As the distribution of the laminated layer thickness, the layer thickness distribution that increases or decreases from one side of the film to the opposite side, or the layer thickness distribution that decreases after the layer thickness increases from one side of the film to the center of the film Also preferred is a layer thickness distribution that increases after the layer thickness decreases from one side of the film toward the center of the film. As the method of changing the layer thickness distribution, there are continuous, linear, equiratio, difference number series, and 10 to 50 layers have almost the same layer thickness, and the layer thickness changes stepwise. Those that do are preferred.

In the laminated film of the present invention, it is preferable to contain an ultraviolet absorber and / or a dye having a maximum wavelength that is the maximum in the visible light short wavelength region exceeding 380 nm and not exceeding 430 nm. The ultraviolet absorber in the present invention refers to an additive having a maximum wavelength that is maximum in the ultraviolet region having a wavelength of 300 to 380 nm. The maximum wavelength in the present invention refers to a peak wavelength having the maximum absorbance when having a plurality of maximum peaks. The ultraviolet absorber and the dye having the maximum wavelength that is maximum in the visible light short wavelength region of more than 380 nm and not more than 430 nm may have the ability to absorb a part of each other region. For example, in an additive having maximums at 375 nm and 390 nm, when the maximum of 375 nm is maximum, the additive is an ultraviolet absorber, and when the maximum of 390 nm is maximum, it exceeds 380 nm in the visible light short wavelength region of 430 nm or less. It is defined as a dye having the maximum maximum wavelength.

In the present invention, the ultraviolet absorber or the dye having the maximum wavelength in the short wavelength range of visible light exceeding 380 nm and not exceeding 430 nm may be contained singly or in combination with one or more kinds of ultraviolet rays. You may contain simultaneously the absorber and the pigment | dye which has the maximum wavelength which becomes the maximum in the visible light short wavelength area | region of 430 nm or less exceeding 380 nm. The ultraviolet absorber and / or the dye having the maximum wavelength that is the maximum in the visible light short wavelength region of more than 380 nm and not more than 430 nm may be contained only in the A layer or only in the B layer. You may make it contain in a layer. In particular, from the viewpoint of suppressing surface precipitation due to the multilayer structure, it is contained only in the B layer located in the inner layer of the laminated film, or compared with the A layer where the B layer located in the inner layer of the laminated film is located in the outermost layer. It is preferable to increase the content concentration. When only the A layer including the outermost layer contains an ultraviolet absorber and a dye having a maximum wavelength exceeding 380 nm and a visible light short wavelength region of 430 nm or less, the contained ultraviolet absorber is precipitated on the film surface. (Bleed-out phenomenon) and the phenomenon that it sublimates and volatilizes near the base easily occur, and this causes the film-forming machine to be contaminated, and the deposits have adverse effects such as defects in the film-forming process. May affect.

Ultraviolet absorbers are generally specialized in the ability to absorb ultraviolet rays in a wavelength region of 380 nm or less, near the boundary between the ultraviolet region and the visible light region (near 380 to 400 nm), or in the short wavelength region of visible light (400 nm to 400 nm). The ability to absorb 430 nm) light is not excellent. Therefore, in order to cut light rays in the vicinity of the boundary between the ultraviolet region and the visible light region (near 380 to 400 nm) and in the short wavelength region of visible light (400 to 430 nm) only by containing the ultraviolet absorber, one described later Except for the long wavelength ultraviolet absorption of the part, it is necessary to make it contain in high concentration. In the case of wavelength cut in the ultraviolet region and the visible light short wavelength region (380 nm to 430 nm), examples of the ultraviolet absorber that can be achieved by a single ultraviolet absorber include 2- (5-chloro-2H-benzotriazole). -2-yl) -6-tert-butyl-4-methylphenol and 2,4,6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3,5-triazine Can be mentioned.

On the other hand, a dye having a maximum wavelength that exceeds the wavelength range of 380 nm to 430 nm or less is generally excellent in cutting performance in the visible light short wavelength region, but has poor ability to cut in the ultraviolet region. Therefore, in order to cut only the maximum wavelength in the visible light short wavelength region exceeding 380 nm and not exceeding 430 nm and cutting the light ray in the ultraviolet region, it exceeds 380 nm, which will be described later, to 430 nm. Except for the dye having the maximum wavelength that is maximum in the visible light short wavelength region below, it is necessary to contain it at a high concentration. Moreover, when it contains in high concentration, since it absorbs the visible light area | region longer than the target wavelength area | region, the outstanding transparency cannot be implement | achieved. Examples of the dye having a maximum wavelength that is the maximum in the visible light short wavelength region of 430 nm or less, exceeding 380 nm, which can be achieved independently, in the ultraviolet wavelength region and the visible light short wavelength region (380 nm to 430 nm), for example, And “LumogenF Violet 570” manufactured by BASF Corporation. In the ultraviolet absorber and the dye having the maximum wavelength that is the maximum in the visible light short wavelength region of more than 380 nm and less than or equal to 430 nm, since each region has strengths, the bleedout due to the addition of high concentration, In order to prevent process contamination associated therewith, it is more effective to combine one or more kinds of ultraviolet absorbers and one or more kinds of dyes having a maximum wavelength in the short wavelength region of visible light exceeding 380 nm and not exceeding 430 nm. preferable.

In the laminated film of the present invention, one or more kinds of ultraviolet absorbers and one or more kinds of dyes having a maximum wavelength in the short wavelength region of visible light exceeding 380 nm and not exceeding 430 nm are combined, and the light transmittance described above is combined. In addition to the above-mentioned two types of ultraviolet absorbers, other ultraviolet absorbers that can be used when achieving the above include benzotriazole, benzophenone, benzoate, triazine, benzoxazinone, salicylic acid, and the like Various kinds of skeleton UV absorbers can be used. When two or more kinds of ultraviolet absorbers are used in combination, the same ultraviolet absorbers may be combined with each other, or different types of ultraviolet absorbers may be combined. Specific examples are illustrated below, but (*) is added after the compound name for compounds having a maximum wavelength in the wavelength region of 320 nm to 380 nm. The ultraviolet absorber in the present invention is preferably an ultraviolet absorber having a maximum absorption wavelength between 320 and 380 nm. When the maximum wavelength is smaller than 320 nm, it is difficult to sufficiently cut the ultraviolet region on the long wavelength side, and a combination with a dye having a maximum wavelength in the visible light short wavelength region exceeding 380 nm and not exceeding 430 nm is used. Even when it is performed, an insufficiently cut region that exhibits a light transmittance of 10% or more in the region at a wavelength of 300 to 380 nm is often generated. Therefore, in order to make the maximum value of the light transmittance in the ultraviolet region with a wavelength of 300 to 380 nm 10% or less, it is preferable to use an ultraviolet absorber marked with (*).

The benzotriazole-based UV absorber is not particularly limited, and examples thereof include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole (*) and 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′-ditertiaryamylphenyl) -5-chlorobenzotriazole (*), 2- (2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″) , 6 " Tetrahydrophthalimidomethyl) -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′-ditertiarypentylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tertiary octylphenyl) benzotriazole, 2,2′-methylenebis (4-tertiaryoctyl-6-benzotriazolyl) ) Phenol (*), 2- (5-Butyloxy-2H-benzotriazol-2-yl) -6-tert-butyl-4-methylphenol (*), 2- (5- Xyloxy-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) Ruphenyl) oxy-2H-benzotriazol-2-yl) -6-tert-butyl-4-methylphenol (*), 2- (5-benzyloxy-2H-benzotriazol-2-yl) -6-tert- Butyl-4-methylphenol (*), 2- (5-hexyloxy-2H-benzotriazol-2-yl) -4,6-ditert-butylphenol (*), 2- (5-octyloxy-2H- Benzotriazol-2-yl) -4,6-ditert-butylphenol (*), 2- (5-dodecyloxy-2H-benzotriazol-2-yl) -4,6-ditert-butylphenol (*), And 2- (5-secondarybutyloxy-2H-benzotriazol-2-yl) -4,6-ditertiarybutylphenol (*).

The benzophenone-based ultraviolet absorber is not particularly limited. For example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2′-dihydroxy-4- Methoxy-benzophenone (*), 2,2'-dihydroxy-4,4'-dimethoxy-benzophenone, 2,2 ', 4,4'-tetrahydroxy-benzophenone, 5,5'-methylenebis (2-hydroxy-4 -Methoxybenzophenone), and the like.

The benzoate-based ultraviolet absorber is not particularly limited, and examples thereof include resorcinol monobenzoate, 2,4-ditertiarybutylphenyl-3,5-ditertiarybutyl-4-hydroxybenzoate, and 2,4-ditertiary acid. Amylphenyl-3,5-ditert-butyl-4-hydroxybenzoate, 2,6-ditert-butylphenyl-3 ′, 5′-ditert-butyl-4′-hydroxybenzoate, hexadecyl-3,5- Examples thereof include di-tert-butyl-4-hydroxybenzoate and octadecyl-3,5-di-tert-butyl-4-hydroxybenzoate.

The triazine-based ultraviolet 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)- -Triazine, 2,4-bis (2-hydroxy-4-octoxyphenyl) -6- (2,4-dimethylphenyl) -s-triazine, 2,4,6-tris (2-hydroxy-4-hexyl) Oxy-3-methylphenyl) -s-triazine (*), 2,4,6-tris (2-hydroxy-4-octoxyphenyl) -s-triazine (*), 2- (4-isooctyloxycarbonyl) Ethoxyphenyl) -4,6-diphenyl-s-triazine (*), 2- (4,6-diphenyl-s-triazin-2-yl) -5- (2- (2-ethylhexanoyloxy) ethoxy) Examples include phenol.

Although it does not specifically limit as a benzoxazinone type ultraviolet absorber, 2,2'-p-phenylenebis (4H-3,1-benzoxazin-4-one) (*), 2,2'-p-phenylene 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, 4-Diyl) bis (4H-3,1-benzooxy) Jin-4-one) (※), 2,2 '- (thiophene-2,5-diyl) bis (4H-3,1-benzoxazin-4-one) (※) and the like.

Examples of other ultraviolet absorbers include salicylic acid-based compounds such as phenyl salicylate, t-butylphenyl salicylate, p-octylphenyl salicylate, and others, and other natural products (for example, oryzanol, shea butter, baicalin). Etc.), biological systems (for example, keratinocytes, melanin, urocanin, etc.) can also be used. Inorganic ultraviolet absorbers are not compatible with the base resin, leading to an increase in haze and worsening the visibility when displaying an image. Therefore, it is not preferable to use them in laminated films for display applications.

The ultraviolet absorber used in the present invention may be the same as the above-described ultraviolet absorber, in which the oxygen atom is replaced with a sulfur atom in the same family. Specifically, an ether group converted into a thioether group, a hydroxyl group into a mercapto group, and an alkoxy group into a thio group may be used. By using an ultraviolet absorber containing a substituent having a sulfur atom, thermal decomposition of the ultraviolet absorber can be suppressed when heated and kneaded into the resin. In addition, by using sulfur atoms and selecting an appropriate alkyl chain, the intermolecular force between the UV absorbers can be suppressed and the melting point can be lowered, so compatibility with thermoplastic resins is improved. Can be raised. By increasing the compatibility, it is possible to maintain transparency, which is an important factor of the optical film, even when a high concentration is added.

Further, the ultraviolet absorber used in the present invention preferably has a long alkyl chain of the functional group constituting the ultraviolet absorber in addition to having a maximum absorption wavelength in the wavelength range of 320 to 380 nm. As the alkyl chain becomes longer, the intermolecular interaction is suppressed and packing of the ring structure is less likely to occur.Therefore, when the film is heat-treated, it becomes difficult for the UV absorbers to form a crystal structure, and the film is whitened. It leads to suppression. The length of the alkyl group contained in the functional group is preferably 18 or less, more preferably 4 or more and 10 or less, and still more preferably 6 or more and 8 or less. When the length of the alkyl chain is longer than necessary, the reactive site is buried in the molecule and the yield of the UV absorber is reduced, which is not realistic.

The ultraviolet absorber may be kneaded as an additive with the thermoplastic resin, or may be copolymerized by reacting with a terminal group or side chain of the thermoplastic resin. By copolymerizing and fixing with the thermoplastic resin that composes the film, it is possible to suppress bleed-out due to molecular thermal motion during heating, so that UV-cutting performance can be maintained for a long time while maintaining transparency. Is possible.

In the laminated film of the present invention, one or more kinds of ultraviolet absorbers and one or more kinds of dyes having a maximum wavelength in the short wavelength region of visible light exceeding 380 nm and not exceeding 430 nm are combined, and the light transmittance described above is combined. As a dye having a maximum wavelength that is maximum in the visible light short wavelength region exceeding 430 nm and 430 nm or less, which can be used in achieving the above, the above-described dye having a maximum wavelength in the visible light short wavelength region exceeding 380 nm and 430 nm or less is used. Other dyes having the maximum maximum wavelength can also be used. In the present invention, the dye having the maximum wavelength that is the maximum in the visible light short wavelength region of 380 nm or more and 430 nm or less can be dissolved in a solvent for the purpose of addition to a hard coat layer or an adhesive layer described later, and chroma. Dyes excellent in heat resistance may be used, and pigments that are more excellent in heat resistance, moist heat resistance, and light resistance than dyes may be used. Pigments can be broadly classified into organic pigments, inorganic pigments, and classical pigments, but it is preferable to use organic pigments from the viewpoint of compatibility with the thermoplastic resin to be added. Although it does not specifically limit as a structure of the pigment | dye which has the maximum wavelength which becomes the visible light short wavelength area | region beyond 380 nm below 430 nm, (beta) naphthol type | system | group, naphthol AS type | system | group, acetoacetic acid arylamide type, acetoacetic acid arylamide type Azo, pyrazolone, β-oxynaphthoic acid, phthalocyanine, copper phthalocyanine, halogenated copper phthalocyanine, metal-free phthalocyanine, copper phthalocyanine lake, azomethine, aniline, alizarin, anthraquinone, isoindo Linone, isoindoline, isoquinoline, indane, indole, quinacridone, quinophthalone, coumarin, dioxazine, thioindigo, naphthalimide, nitrone, perinone, perylene, benzylidine, natural Organic dyes can be mentioned.

As described above, it is more preferable that the dye having the maximum wavelength that is the maximum in the visible light short wavelength region of more than 380 nm and not more than 430 nm has the maximum wavelength of 390 to 420 nm. When a material having a maximum wavelength in a wavelength region longer than 430 nm is selected, the light transmittance at 440 nm is less than 80% unless a dye having a very narrow band cutting ability is selected. As the dye having a maximum wavelength in the wavelength band of 390 nm to 420 nm, azomethine, indole, quinone, triazine, naphthalimide, phthalocyanine, and benzylidine can be preferably used.

The ultraviolet absorber used in the present invention and / or the dye having a maximum wavelength in the visible light short wavelength region exceeding 380 nm and not exceeding 430 nm preferably has a triazine skeleton. Since triazine-based absorbents generally have a high thermal decomposition temperature and excellent heat resistance, they are less likely to cause deterioration even when kneaded into a resin and exposed to heat for a long time in an extruder. Moreover, since the volatilization and surface precipitation of the absorbent itself hardly occur and the effect of making it difficult to deposit oligomers and other highly sublimable additives, it can be preferably used. In addition, since the absorption coefficient is high, the concentration required for achieving the desired cutability is low, and it is less likely to contaminate the film-forming process even when discharged from the die in the form of a sheet. It is.

When the laminated film of the present invention contains a UV absorber and / or a dye having a maximum wavelength in the short wavelength region of visible light exceeding 380 nm and not exceeding 430 nm, ultraviolet rays contained in a specific layer of the laminated film The sum of the contents of the absorber and / or the pigment having the maximum wavelength that is the maximum in the visible light short wavelength region of 430 nm or more and exceeding 380 nm is Mn [wt%], and the layer thickness of the added layer is Tn [μm] In this case, it is preferable that Σ (Mn × Tn) obtained by adding the product of the sum of the contents and the layer thickness for all layers of the laminated film is 50 [wt% · μm] or less. If it is larger than 50 [wt% · μm], the light transmittance is lowered and the white turbidity (haze value) of the film is increased, which causes a problem of deterioration in visibility when mounted on a liquid crystal image display device or the like. It may not be preferable. Although the total content is changed with the film thickness and the light absorption ability of various additives, no lower limit is provided, but as described above, required for an optical film used in an image display device, a polarizer or An amount of addition sufficient to have sufficient UV-cutting performance for protecting liquid crystal molecules, light emitting layers and the like is required.

In the thermoplastic resin of the present invention, there are various additives other than ultraviolet absorbers and pigments having a maximum wavelength in the short wavelength region of visible light exceeding 380 nm and not exceeding 430 nm, such as antioxidants, heat-resistant stability Agents, weathering stabilizers, organic lubricants, organic or inorganic fine particles, fillers, antistatic agents, nucleating agents and the like may be added to such an extent that the film properties that should be originally satisfied are not deteriorated. In particular, in applications where optical performance is required to be maintained even when light is irradiated for a long time, among the dyes having a maximum wavelength in the short wavelength region of visible light exceeding 380 nm and not exceeding 430 nm, the bright color In the case of using a dye having, there is a tendency that the absorption performance is lost by receiving ultraviolet rays having strong energy as compared with ultraviolet absorbers and pigments. Therefore, it is preferable to use a compound having a role of converting the energy held by ultraviolet rays into vibrational energy within the molecule, converting the converted vibrational energy into heat energy, etc., and releasing it to the outside. It is also preferable to use an additive such as an antioxidant or a singlet oxygen quencher that suppresses photo-oxidative deterioration through energy conversion.

The light stabilizer is added mainly for capturing radicals generated by photooxidation, and is 0.01% by weight or more and 1% by weight with respect to the total film weight of the laminated film of the present invention. It is preferable to contain below. In particular, a hindered amine compound having a 2,2,6,6-tetramethyl-piperidine ring is preferable, and the 1-position of piperidine is hydrogen, an alkyl group, an alkoxy group, a hydroxy group, an oxy radical group (—O ·), an acyloxy group. A group or an acyl group is preferable, and the 4-position is more preferably a hydrogen atom, a hydroxy group, an acyloxy group, an amino group which may have a substituent, an alkoxy group or an aryloxy group. Also preferred are those having a plurality of 2,2,6,6-tetramethyl-piperidine rings in one molecule. Examples of such compounds include TINUVIN770DF, TINUVIN 152, and TINUVIN123 manufactured by BASF (formerly Ciba Specialty Chemicals), Adeka Stub LA-72, and Adeka Stub LA-81 manufactured by Adeka.

In the laminated film of the present invention, the light stability can be further improved by using an antioxidant and / or a singlet oxygen quencher in addition to the hindered amine light stabilizer. Photodegradation of the dye is caused by an oxidation reaction. Oxygen molecules function as an oxidant, so that auto-oxidation with radical generation occurs, and the excitation energy of the dye propagates to the oxygen molecules, so that oxygen becomes a singlet oxidation state. Examples include oxygen oxidation and oxidation with superoxide ions. By using an antioxidant, a quencher for releasing excitation energy, etc., these oxidation reactions can be further suppressed.

The antioxidant to be used in combination with the light stabilizer is not particularly limited as long as it is a commonly used antioxidant, but a phosphorus-based antioxidant and a phenol-based antioxidant can be preferably used. . In addition, the combined use of a phosphorus-based antioxidant and a phenol-based antioxidant allows the efficacy of the antioxidant to be maintained for a long time, and therefore it is preferable to appropriately use a combined system. The addition concentration of the antioxidant is preferably 0.01% by weight or more and 1% by weight or less, and more preferably 0.05% by weight or more and 0.3% by weight or less. When it is 0.01% by weight or less, the effect as an antioxidant is reduced, and when it is 1% by weight or more, there is a possibility that the antioxidant is volatilized due to excessive addition.

A singlet oxygen quencher to be used in combination with a light stabilizer is a compound that can deactivate singlet oxygen by energy transfer from oxygen in a singlet oxidation state, for example, an ethylene-based compound such as tetramethylethylene and cyclopentene, Amines such as diethylamine, triethylamine, N-ethylimidazole, condensed polycyclic aromatic compounds such as substituted naphthalene, dimethylnaphthalene, dimethoxyanthracene, anthracene, diphenylanthracene, 1,3-diphenylisobenzofuran, 1,2, In addition to aromatic compounds such as 3,4-tetraphenyl-1,3-cyclopentadiene and pentaphenylcyclopentadiene, metal complexes having a ligand can also be exemplified. Examples of the metal complex compounds include transition metal coordination complexes such as nickel complexes, cobalt complexes, copper complexes, manganese complexes, and platinum complexes having a ligand such as bisdithio-α-diketone, bisphenyldithiol, and thiobisphenol. A compound can be mentioned. The singlet oxygen quencher is preferably added in an amount of 0.5 wt% or more and 10 wt% or less, more preferably 1 wt% or more and 8 wt% or less based on the amount of the absorbent to be oxidized and deteriorated. It is. In addition, it is most preferable to use the light stabilizer in combination with an antioxidant and a singlet oxygen quencher because the oxidation deterioration due to radicals can be effectively prevented.

In the laminated film of the present invention, it is preferable that 51 or more layers of the thermoplastic resin A and the thermoplastic resin B are alternately laminated. As described above, by alternately laminating resins with different optical properties, it is possible to reflect light of a specific wavelength from the relationship between the difference in refractive index of each layer and the layer thickness, and to express interference reflection. Is possible. In addition, since the multiple interference reflection effect between the layers occurs for the light beam having the wavelength in the interference reflection region, the light beam travels through the optical path length equal to or greater than the film thickness. Or, when a pigment having a maximum wavelength in the visible light short wavelength region exceeding 380 nm and not exceeding 430 nm is added, the amount of absorption is increased, and ultraviolet rays are compared with a normal laminated film having no interference reflection effect. It becomes possible to suppress the addition amount of the absorbent. Thus, if the effect of multiple interference reflection is utilized, the amount of various additives added can be suppressed to a small amount by targeting the ultraviolet region and / or the short-wavelength visible light region, and is an object of the present invention. Bleed-out suppression during film formation and quality after long-term reliability tests are well maintained. The number of laminated films of the present invention is more preferably 200 layers or more, and still more preferably 400 layers or more. The above-described interference reflection effect is more preferable as the number of layers is increased because the higher the number of layers, the higher the reflectance can be achieved with respect to light in the target wavelength band. In addition, when the number of layers is large, it is expected that each resin is uniformly distributed and stable film forming properties and mechanical properties are obtained. As the number of layers increases, the manufacturing cost increases with an increase in the size of the manufacturing apparatus and the handling property deteriorates due to the increase in film thickness.

The laminated film of the present invention, it is preferable flexural rigidity per unit length is ^{^{1.0 × 10 -7 [N · m}} 2] or less. Bending rigidity is an index representing strength against bending, and the higher the value, the harder the film becomes and the more easily creased during bending. The bending rigidity per unit length is expressed by E × I, where E is the elastic modulus [N / m ² ] in the bending direction of the optical functional film, I is the cross-sectional secondary moment per unit length, and I = ^{b × h 3/12 (b} : unit length [m] :, h: film thickness [m]) it is. Since this parameter is particularly strongly affected by the film thickness h, it indicates that the thinner the film, the stronger the bending. When the present laminated film is produced by the biaxial stretching process described later, the bending rigidity is calculated for each of the longitudinal direction and the width direction of the laminated film, and the higher numerical value is 1.0 × 10 ⁻⁷ [N · m ² ] is required to satisfy the following. The bending rigidity is preferably 3.0 × 10 ⁻⁸ [N · m ² ] or less, and more preferably 1.0 × 10 ⁻⁸ [N · m ² ] or less.

The laminated film of the present invention preferably has a Δhaze of 2.0 or less when treated at 85 ° C. and 85% RH for 250 hours. The 85 ° C. and 85% RH conditions are accelerated humidity and heat resistance reliability test conditions for display applications. However, since the temperature and humidity are high, the UV absorber added inside and / or visible light exceeding 380 nm and below 430 nm. Dyes having a maximum wavelength in the short wavelength region, oligomers derived from resins, and the like are easily deposited on the film surface by thermal motion. If the haze value is not less than 2.0 under these conditions, the diffused light becomes strong, so that the optical film itself appears white and turbid, and the light transmittance at the time of mounting deteriorates, causing a problem in visibility. More preferably, it is 1.5 or less as a haze value after an accelerated heat test, More preferably, it is 1.0 or less.

The laminated film of the present invention cuts light rays not only in the ultraviolet region but also in the vicinity of the boundary between the ultraviolet region and the visible light region (around 410 nm) and has a high light transmittance in the visible light region. Preferably used. As a display application film, for example, in the case of a liquid crystal image display device, a polarizer protective film or retardation film constituting a polarizing plate, various surface treatment films located on the front surface of the display having anti-glare or clear hard coat, and a position immediately before the backlight. Brightness enhancement films, antireflection films, transparent conductive films, and the like. In the case of an organic EL image display device, a λ / 4 retardation film or a polarizer protective film constituting a circularly polarizing plate located in front of the light emitting layer, and an optical built-in for the purpose of protecting contents from external light A film etc. are mentioned. In particular, when conditions such as improved light resistance and uniform orientation angle are achieved, a polarizer protective film located on the most visible side of the polarizing plate, or a cover glass on the viewing side of the polarizing plate and on the outermost surface of the display It is most preferable that it is disposed in a portion located inside the window film and the window film in order to take advantage of the properties of protecting the display contents from ultraviolet rays and maintaining the polarization state. However, the laminated film of the present invention is not limited to display applications, but in fields that require light cut in the visible light short wavelength region of wavelength 410 nm or less, such as window films for building materials and automotive applications, signs for industrial material applications, etc. Steel plate laminating film, and for electronic device applications, photolithographic material process / release film, other food, medical, and ink fields, etc. It is possible.

Next, a preferred method for producing the laminated film of the present invention will be described below. Of course, the present invention should not be construed as being limited to such examples.

Prepare thermoplastic resin in the form of pellets. The pellets are dried in hot air or under vacuum as necessary, and then supplied to a separate extruder. In the extruder, the resin melted by heating to a temperature higher than the melting point is made uniform in the amount of resin extruded by a gear pump or the like, and foreign matter or denatured resin is removed through a filter or the like. These resins are formed into a desired shape by a die and then discharged. And the film laminated | stacked in the multilayer discharged | emitted from die | dye is extruded on cooling bodies, such as a casting drum, and is cooled and solidified, and a casting film is obtained. At this time, it is preferable to use a wire-like, tape-like, needle-like, or knife-like electrode to be brought into close contact with a cooling body such as a casting drum by an electrostatic force and rapidly solidify. Also preferred is a method in which air is blown out from a slit-like, spot-like, or planar device to be brought into close contact with a cooling body such as a casting drum and rapidly cooled and solidified, or brought into close contact with a cooling body with a nip roll and rapidly cooled and solidified.

Further, a plurality of resins of thermoplastic resin A and thermoplastic resin B are sent out from different flow paths using two or more extruders, and are sent into a multilayer laminating apparatus. As the multilayer laminating apparatus, a multi-manifold die, a feed block, a static mixer, or the like can be used. In particular, in order to efficiently obtain the configuration of the present invention, it is preferable to use a feed block having a fine slit. When such a feed block is used, the apparatus does not become extremely large, so that the amount of foreign matter generated due to thermal degradation is small, and even when the number of stacks is extremely large, highly accurate stacking is possible. Also, the stacking accuracy in the width direction is significantly improved as compared with the prior art. Moreover, in this apparatus, since the thickness of each layer can be adjusted with the shape (length, width) of a slit, it becomes possible to achieve arbitrary layer thickness.

In this way, the molten multilayer laminate formed in a desired layer configuration is guided to a die, and a casting film is obtained as described above.

The casting film thus obtained is preferably biaxially stretched in the longitudinal direction and the width direction. The stretching may be biaxial stretching sequentially or simultaneously biaxial stretching. Further, 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 stretching for imparting molecular orientation in the longitudinal direction to the film, and is usually performed by a difference in peripheral speed of the roll, and this stretching may be performed in one step. Alternatively, a plurality of roll pairs may be used in multiple stages. The stretching ratio varies depending on the type of resin, but usually 2 to 15 times is preferable, and 2 to 7 times is particularly preferable when polyethylene terephthalate is used as one of the resins constituting the laminated film. The stretching temperature is preferably set within the range of the glass transition temperature of the resin constituting the laminated film to the glass transition temperature + 100 ° C.

The uniaxially stretched film thus obtained is subjected to surface treatment such as corona treatment, flame treatment, and plasma treatment as necessary, and then functions such as slipperiness, easy adhesion, and antistatic properties are provided. It may be applied by in-line coating.

Subsequently, stretching in the width direction refers to stretching for imparting a width direction orientation to the film. Usually, the film is stretched in the width direction by using a tenter while conveying the both ends of the film with clips. The stretching ratio varies depending on the type of resin, but usually 2 to 15 times is preferable, and when polyethylene terephthalate is used as one of the resins constituting the film, 2 to 7 times is particularly preferable. The stretching temperature is preferably from the glass transition temperature of the resin constituting the laminated film to the glass transition temperature + 120 ° C.

The film thus biaxially stretched is subjected to a heat treatment at a temperature not lower than the stretching temperature and not higher than the melting point in the tenter, uniformly cooled slowly, cooled to room temperature, and wound. Further, if necessary, a relaxation treatment or the like may be used in the longitudinal direction and / or the width direction during the slow cooling from the heat treatment in order to impart a low orientation angle and thermal dimensional stability of the film.

Next, the case of simultaneous biaxial stretching will be described. In the case of simultaneous biaxial stretching, the resulting cast film is subjected to surface treatment such as corona treatment, flame treatment, and plasma treatment as necessary, and then, such as slipperiness, easy adhesion, antistatic properties, 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 stretched in the longitudinal direction and the width direction simultaneously and / or stepwise. The simultaneous biaxial stretching machine includes a pantograph method, screw method, drive motor method, and linear motor method. A linear motor system is preferred. Although the stretching ratio varies depending on the type of resin, it is usually preferably 6 to 50 times as the area ratio. When polyethylene terephthalate is used as one of the resins constituting the laminated film, the area ratio is 8 to 30 times. Is particularly preferably used. In particular, in the case of simultaneous biaxial stretching, it is preferable to make the stretching ratios in the longitudinal direction and the width direction the same and to make the stretching speeds substantially equal in order to suppress the in-plane orientation difference. The stretching temperature is preferably from the glass transition temperature of the resin constituting the laminated film to the glass transition temperature + 120 ° C.

The film thus biaxially stretched is preferably subsequently subjected to a heat treatment not less than the stretching temperature and not more than the melting point in the tenter in order to impart flatness and dimensional stability. In this heat treatment, in order to suppress the distribution of the main orientation axis in the width direction, it is preferable to perform relaxation treatment in the longitudinal direction instantaneously immediately before and / or immediately after entering the heat treatment zone. After being heat-treated in this way, it is gradually cooled down uniformly, then cooled to room temperature and wound up. Moreover, you may perform a relaxation | loosening process in a longitudinal direction and / or the width direction at the time of annealing from heat processing as needed. Immediately before and / or immediately after entering the heat treatment zone, a relaxation treatment is performed in the longitudinal direction.

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. In addition, you may give an embossing process to both ends of a film for winding-up improvement at the time of winding.

The thickness of the laminated film of the present invention is not particularly limited, but is preferably 1 to 500 μm. In accordance with the recent trend toward thin film for display applications, it is preferably 40 μm or less, more preferably 20 μm, and even more preferably 15 μm or less. Although there is no lower limit, an ultraviolet absorber and / or a dye having a maximum wavelength in the visible light short wavelength region of more than 380 nm and not more than 430 nm is added to provide a thin film with sufficient cut ability in the ultraviolet and visible light short wavelength region In order to impart to the film, it is necessary to have a certain thickness, and it is preferable that the thickness is practically 10 μm or more. When the thickness is less than 10 μm, the desired optical performance cannot be imparted, and when a hard coat layer described later is provided, the laminated film may be curled along with the curing treatment.

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

The laminated film of the present invention is preferably provided with a hard coat layer (C layer) composed mainly of the curable resin C in order to add functions such as scratch resistance and dimensional stability to the uppermost layer. . In the case of a display application film, in the long-term reliability test under severe conditions such as the heat shock test in which the temperature is raised and lowered from around 100 ° C. to below the freezing point, including the above-mentioned 85 ° C. and 85% RH accelerated heat resistance test It is required that the film properties do not change. In the case of a laminated film crystallized by stretching, if the long-term reliability test is performed, the film size may change due to thermal shrinkage. In the case of the laminated film of the present invention, the thickness of the film is caused by thermal shrinkage. As the absorption performance of various absorbents is improved more than necessary, problems such as undesired absorption in the visible light region and a shift in the reflection band to cut visible light on the longer wavelength side are caused. Since a point arises, it is not preferable. 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 the properties of the film. In addition, by laminating a hard coat layer with high crosslinkability, precipitation of oligomers and additives contained in the laminated film can be suppressed. The hard coat layer may be coated directly on the laminated film, and is coated on an in-line water-based coating layer that can impart functions such as slipperiness and easy adhesion as described in the manufacturing method above. May be.

The above-mentioned coating layer not only provides functions such as slipperiness and easy adhesion, but also improves the adhesion with the laminated film when laminating a hard coat layer mainly composed of the curable resin C. It is preferable to apply to achieve the above. In particular, when polyethylene terephthalate is used as the resin A and acrylic resin is used as the curable resin B as in the examples described later, the former has a refractive index of about 1.65 and the latter has a refractive index of about 1.50. Increases the adhesion, which causes deterioration of adhesion. Therefore, the refractive index of the coating layer preferably has a value of 1.50 to 1.60, more preferably 1.55 to 1.58.

The hard coat layer mainly composed of the curable resin C may be provided on one side. However, precipitation of oligomers and additives generally occurs from both sides of the film, and in addition, the hard coat layer is laminated only on one side. The shrinkage stress due to curing acts strongly on the surface side, and there is a possibility that the laminated sheet itself curls remarkably depending on the laminated thickness of the hard coat layer. Therefore, it is more preferable that the hard coat layer is applied to both surfaces of the laminated film.

The curable resin C used in the laminated film of the present invention is preferably highly transparent and durable. For example, an acrylic resin, a urethane resin, a fluorine resin, a silicon resin, a polycarbonate resin, or a vinyl chloride resin is used alone or Can be used as a mixture. In view of curability, flexibility, and productivity, the curable resin C is preferably made of an active energy ray curable resin such as an acrylic resin typified by a polyacrylate resin. Moreover, when adding the abrasion resistance at the time of a bending | flexion required when applying as a film for flexible displays, it is preferable that the curable resin C consists of a thermosetting urethane resin.

The active energy ray-curable resin used as a constituent component of the hard coat layer includes, for example, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, as monomer components constituting the active energy ray-curable resin, Dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, bis (methacryloylthio) Phenyl) sulfide, 2,4-dibromophenyl (meth) acrylate, 2,3,5-tribromophenyl (meth) acrylate, 2,2-bis (4- (meth) acryloyloxy) Enyl) propane, 2,2-bis (4- (meth) acryloyloxyethoxyphenyl) propane, 2,2-bis (4- (meth) acryloyloxydiethoxyphenyl) propane, 2,2-bis (4- ( (Meth) acryloylpentaethoxyphenyl) propane, 2,2-bis (4- (meth) 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-fur Nylphenyl) propane, bis (4- (meth) acryloyloxyphenyl) sulfone, 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) acryloyloxypentaethoxyphenyl) sulfide, bis (4- (meth) acryloyloxyethoxy-3-phenylphenyl) sulfide, bis (4- (me Use polyfunctional (meth) acrylic compounds such as) acryloyloxyethoxy-3,5-dimethylphenyl) sulfide, di ((meth) acryloyloxyethoxy) phosphate, tri ((meth) acryloyloxyethoxy) phosphate These can be used alone or in combination of two or more.

In addition to these polyfunctional (meth) acrylic compounds, styrene, chlorostyrene, dichlorostyrene, bromostyrene, dibromostyrene, divinyl are used to control the hardness, transparency, strength, refractive index, etc. of active energy ray-curable resins. 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 and (meth) acrylic acid can be used. These may be used alone or in combination of two or more.

As a method of curing the active energy ray-curable resin, for example, a method of irradiating with 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.

In the active energy ray-curable resin used in the present invention, isopropyl alcohol, ethyl acetate, methyl ethyl ketone, for the purpose of improving the workability during coating and controlling the coating film thickness, without impairing the effects of the present invention, An organic solvent such as toluene can be blended.

In the present invention, the active energy ray means an electromagnetic wave that polymerizes an acrylic vinyl group such as an ultraviolet ray, an electron beam, and radiation (α ray, β ray, γ ray, etc.). preferable. As the ultraviolet ray 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, or the like can be used. The electron beam method is advantageous in that the apparatus is expensive and requires operation under an inert gas, but it does not need to contain a photopolymerization initiator or a photosensitizer.

The thickness of the hard coat layer should be appropriately adjusted depending on the method of use, but it is usually preferably 1 to 6 μm, more preferably from the viewpoint of compatibility between the thin film tendency for display applications and the hard coat performance. Is from 1 to 3 μm, more preferably from 1 to 1.5 μm. When the thickness of the hard coat layer is thicker than 6 μm, the laminated film may lose the curing shrinkage force of the hard coat layer when the coating substrate is cured, and the curling of the laminated sheet may occur strongly.

The thermosetting urethane resin used as a component of the hard coat layer mainly composed of the curable resin C for adding scratch resistance includes a polycaprolactone segment and a polysiloxane segment and / or a polydimethylsiloxane segment. A resin obtained by cross-linking a copolymer resin having an isocyanate group with a compound having a thermal reaction is preferable. By applying the thermosetting urethane resin, it becomes possible to strengthen the hard coat layer and at the same time promote the elastic recovery and to add scratch resistance to the laminated film.

The polycaprolactone segment constituting the thermosetting urethane resin exhibits an effect of elastic recovery, and radically polymerizable polycaprolactone such as polycaprolactone diol, polycaprolactone triol, and lactone-modified hydroxyethyl acrylate can be used.

The polysiloxane and / or polydimethylsiloxane segment constituting the thermosetting urethane resin has the effect of improving the lubricity of the surface and reducing the frictional resistance due to the surface coordination of these components. As the resin having a polysiloxane segment, tetraalkoxysilane, methyltrialkoxysilane, dimethyldialkoxysilane, γ-glycidoxypropyltrialkoxysilane, γ-methacryloxypropyltrialkoxysilane, and the like can be used. On the other hand, as a resin having a polydimethylsiloxane segment, various vinyl monomers such as methyl acrylate, isobutyl acrylate, methyl methacrylate, n-butyl methacrylate, styrene, α-methyl styrene, acrylonitrile, vinyl acetate, A copolymer obtained by copolymerizing vinyl chloride, vinyl fluoride, acrylamide, methacrylamide, N, N-dimethylacrylamide, or the like can be preferably used.

A hard coat layer made of a thermosetting urethane resin is formed by linking and reacting resins and compounds at an arbitrary temperature to volatilize the solvent in the layer and at the same time thermally crosslink. In order to promote the thermal crosslinking reaction of the hard coat layer, the temperature in the heating step is preferably 150 ° C. or higher, more preferably 160 ° C. or higher. The heating temperature is preferably high, but it is preferable to perform heat treatment at 170 ° C. or lower in consideration of generation of shrinkage wrinkles due to thermal shrinkage of the substrate. The heating time is 1 minute or longer, preferably 2 minutes or longer, and the upper limit is not particularly defined, but is preferably within 5 minutes from the viewpoint of dimensional stability and transparency of the laminated film. Thus, the laminated sheet that has been heat-treated at a high temperature for a short time is subjected to an aging treatment at a temperature of 20 ° C. to 80 ° C. for 3 days or more, more preferably 7 days or more. It is preferable in terms of improving the degree.

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

As the compound having an alicyclic epoxy group, those having about 2 to 5 epoxy groups are preferable from the viewpoint of low viscosity, curability and adhesive strength. 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane Examples include carboxylate.

As the polyacrylate of the polyol, those having about 2 to 10 carbon atoms are preferable because the adhesion to the polarizer is improved while lowering the viscosity, and neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, Examples include 3-methyl-1,5-pentanediol dimethacrylate.

As an oxetane compound, the adhesion development rate after light irradiation can be improved, and adhesion can be developed even in an environment where the relative humidity varies. 3-ethane-3-oxetanemethanol, 3,3 ′-(oxybismethylene) bis (3-ethyloxetane), and the like can be preferably used.

As a polymer using acrylic acrylate as a monomer, it has an effect of improving the adhesive strength after the accelerated moist heat resistance test, and includes methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, isobutyl methacrylate. It is preferable to use an alkyl methacrylate having 1 to 10 carbon atoms such as the above, and it is most preferable to use an acrylic methacrylate having 1 to 4 carbon atoms.

Appropriate amounts of each of the above components can be blended and cured at room temperature with the above-mentioned various active energy rays as a cationic photopolymerization initiator. As the cationic photopolymerization initiator, an aromatic diazonium salt such as benzenediazonium, an aromatic sulfonium salt such as triphenylsulfonium, an aromatic iodonium salt such as diphenyldiiodonium, or a combination of two or more of these may be used. I can do it. It is also possible to use a radical photopolymerization initiator in order to exhibit sufficient crosslinking reactivity with a small amount of light irradiation.

The hard coat layer may contain the various ultraviolet absorbers described above and / or a dye having a maximum wavelength that is the maximum in the visible light short wavelength region of more than 380 nm and not more than 430 nm. By adding it separately from the hard coat layer, it is possible to reduce the addition amount of the UV absorber added in the resin and the dye having the maximum wavelength that exceeds 380 nm and reaches the maximum in the visible light short wavelength region of 430 nm or less. The bleed-out phenomenon that occurs during resin extrusion can be suppressed, which is preferable. In addition, when a dye having a maximum wavelength exceeding 380 nm and not exceeding 430 nm is added to the hard coat layer, the blue reflection hue from the laminated film to the viewing side is reduced by absorption of the dye. This is preferable because clear whiteness and blackness when an image is displayed can be expressed.

The addition concentration of the ultraviolet absorber added to the hard coat layer and / or the dye having the maximum wavelength in the visible light short wavelength region exceeding 380 nm and below 430 nm is based on the entire resin composition constituting the hard coat layer. It is preferably 10 wt% or less, and more preferably 5 wt% or less. The additive concentration should be adjusted as appropriate in order to achieve the target cut performance in view of the thickness of the hard coat layer involved in the absorption performance and cut performance of the additive. During the accelerated reliability test, there is a possibility of surface precipitation of various additives, and the adhesion between the laminated film and the hard coat layer may deteriorate.

In addition, in the aspect of the laminated sheet, the sum Mn [% by weight] of the content of the ultraviolet absorber contained above and / or the pigment having the maximum wavelength that exceeds 380 nm and reaches the maximum in the visible light short wavelength region of 430 nm or less. And, it is preferable that Σ (Mn × Tn) obtained by adding the product of Tn [μm] to the total thickness of the layer of the additive layer is 50 [wt% · μm] or less.

A functional layer such as an impact absorbing layer or an antireflection (AR) layer can be further provided on the hard coat layer containing the curable resin C as a main component, if necessary. In particular, the AR layer is preferably laminated as a functional layer because it has an effect of improving visibility in image display applications.

You may have an adhesion layer which contains the pigment | dye which has the pigment | dye which has the maximum wavelength which becomes the largest in the visible light short wavelength area | region of 430 nm or more exceeding 380 nm on at least one side among the laminated | multilayer film of this invention. In the case of a display film, the pressure-sensitive adhesive layer may be positioned on the viewing side, on the display inner side, or on both sides of the laminated film of the present invention.
However, when achieving the target wavelength cut through the laminated film and the adhesive layer, the dye is used as a pigment having a maximum wavelength that is the maximum in the visible light short wavelength region exceeding 380 nm and not exceeding 430 nm. In this case, as described above, the absorption performance is lost by receiving ultraviolet rays with strong energy. Therefore, the laminated film contains an ultraviolet absorber, the adhesive layer contains an ultraviolet absorber and / or a pigment having a maximum wavelength in the short wavelength region of visible light shorter than 430 nm but not more than 430 nm. Since the deterioration of the pigment can be sufficiently prevented by the reflection and absorption performance of the laminated film, it is a preferable embodiment.

The pressure-sensitive adhesive layer may be applied directly to the laminated film substrate, then dried to form a pressure-sensitive adhesive layer, and further bonded to the release sheet to obtain a pressure-sensitive adhesive sheet. The pressure-sensitive adhesive applied to the release sheet is laminated. A method of transferring onto a film substrate may also be used. Various coating methods such as a roll coater, a die coater, a bar coater, a lip coater, a gravure coater, and a blade coater can be used as the coating method. 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 pressure-sensitive adhesive layer thickness is less than 5 μm, the pressure-sensitive adhesive performance may be insufficient, and when it exceeds 150 μm, the cost of the pressure-sensitive adhesive sheet itself increases, which is not desirable. The type of the pressure-sensitive adhesive is not particularly limited, but is described as a curable resin used for adding the above-described adhesion and adhesion improvement, acrylic optical pressure-sensitive adhesive (OCA), It is most preferable to use a liquid acrylic optical adhesive (LOCA) because of excellent transparency and durability.

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.

(Characteristic measurement method and effect evaluation method)
The characteristic measuring method and the effect evaluating method in the present invention are as follows.

(1) Layer thickness, number of layers, layered structure The layer structure of the film was determined by observation with a transmission electron microscope (TEM) for a sample obtained by cutting a cross section using a microtome. That is, using a transmission electron microscope H-7100FA 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-sectional photograph was taken, and the layer structure 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. Also, in accordance with the thickness of the thinnest layer (thin film layer) among all the layers that can be captured in one image, when the thin film layer thickness is less than 50 nm, the thin film layer thickness is 50 nm or more and 500 nm. When it was less than 40,000 times, and when it was 500 nm or more, observation was carried out at a magnification of 10,000 times, and the layer thickness, the number of layers, and the layered structure were specified.

(2) Light transmittance A spectrophotometer U-4100 manufactured by Hitachi was used. An integrating sphere was attached, and the relative transmittance in the wavelength range of 300 to 450 nm was measured when the reflection of the aluminum oxide standard white plate (attached to the main body) was 100%. For the wavelength of 410 nm and the wavelength of 440 nm, the transmittance value at the wavelength was read, and for the wavelength range of 300 to 380 nm, the maximum transmittance in the range was read. As conditions, the scanning speed was set to 600 nm / min, the sampling pitch was set to 1 nm, and the measurement was continuously performed.

(3) Average light reflectance Hitachi spectrophotometer U-4100 was used. An integrating sphere was attached, and the relative reflectance in the region of 300 to 400 nm was measured when the reflection of the aluminum oxide standard white plate (attached to the main body) was 100%, and the average light reflectance in this range was determined. As conditions, the scanning speed was set to 600 nm / min, the sampling pitch was set to 1 nm, and the measurement was continuously performed.

(4) Hard coat application (Examples 22 to 32)
A hard coat layer comprising an ultraviolet absorber described in Examples 22 to 32, which will be described later, and a dye having a maximum wavelength exceeding 380 nm and a maximum wavelength in the visible light short wavelength region of 430 nm or less. Active energy ray-curable urethane acrylic resin (purple light UV-1700B [refractive index: 1.50 to 1.51] manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) is uniformly applied on the outermost surface of the laminated film using a bar coater It was applied to. Subsequently, the integrated irradiation intensity was 180 mJ / cm with a concentrating high-pressure mercury lamp (H04-L41 manufactured by Eye Graphics Co., Ltd.) having an irradiation intensity of 120 W / cm ² set at a height of 13 cm from the surface of the hard coat layer. Ultraviolet rays were irradiated so as to be ² and cured to obtain a laminated sheet in which a hard coat layer was laminated on the laminated film. In addition, an industrial UV checker (UVR-N1 manufactured by Nippon Battery Co., Ltd.) was used for measuring the cumulative irradiation intensity of ultraviolet rays.

(5) Evaluation of bleed-out resistance The light was irradiated to the vicinity of the width direction edge of the polymer which came out of the die at the time of film formation, and the presence or absence of generation of white smoke (volatilization from the die) was confirmed. The absence of white smoke (volatilization from the base) was evaluated as having excellent bleed-out resistance.

(6) 85 ° C. and 85% RH accelerated moist heat resistance test (haze fluctuation (Δhaze) evaluation)
The produced laminated film was cut out from the central part in the film width direction at 10 cm in the longitudinal direction and 10 cm in the width direction, sandwiched between plain papers and left in a constant temperature and humidity chamber at 85 ° C. and 85% RH for 250 hours. The amount of change in value was evaluated. The haze measurement was performed according to the former JIS-K-7105 using a haze meter (HGM-2DP) manufactured by Suga Test Instruments Co., Ltd. Three points were measured at random on the film surface, and the average value was taken as the measurement result.
◎: Haze value fluctuation amount is less than 1.0% ○: Haze value fluctuation amount is 1.0% or more and less than 1.5% Δ: Haze value fluctuation amount is 1.5% or more and less than 2.0% ×: Haze value The fluctuation amount is 2.0% or more.

(7) Flexural rigidity In order to calculate the elastic modulus of the sample, a tensile tester (Orientec Tensilon UCT-100) was used. The laminated film was cut into strips having a length of 150 mm and a width of 10 mm, and a tensile test was carried out with an initial tensile chuck distance of 50 mm and a tensile speed of 300 mm / min. The measurement environment was set to an atmosphere of room temperature 23 ° C. and relative humidity 65%, and the elastic modulus (Young's modulus) was calculated from the obtained load-strain curve. The number of samples was 5, and the average value of these was the elastic modulus of the sample. The maximum value of the elastic modulus of the sample was determined by measuring in the same manner by changing the direction every 10 ° from −90 ° to 90 ° with respect to the film plane, with the film longitudinal direction being 0 °. The thickness of the measured sample was measured using a contact-type thickness meter (Digi Microhead MH-15M manufactured by Nikon Corporation), and the bending stiffness value was calculated by applying the thickness to the above-described bending stiffness equation.

(8) Flexural resistance test A sample with a width of 5 cm and a length of 9 cm is cut out with respect to the longitudinal direction and the width direction of the laminated film, respectively, and a planar body-unloaded U-shaped extension tester manufactured by Yuasa Equipment Systems Co., Ltd. Used to conduct a flex resistance test. In a measurement atmosphere at a room temperature of 23 ° C. and a relative humidity of 65%, a bending rate was set to 50 times / minute, a bending radius was set to 1 mm, and a bendability test of 1 million times was performed. The number of samples was 3, and the presence or absence of scratches or creases was visually confirmed as compared with the laminated film before the test. In all three samples, when there was no scratch or crease, good bending resistance (◯), and when even one sample was scratched or creased, poor flex resistance (×).

(9) Glass transition temperature and melting point A differential scanning calorimeter EXSTAR DSC 6220 manufactured by Seiko Electronics Industry Co., Ltd. was used. Measurement and temperature reading were performed according to JIS-K-7122 (1987). A 10 mg sample of a thermoplastic resin was heated from 25 ° C. to 300 ° C. at a rate of 10 ° C./min on an aluminum tray, then rapidly cooled, and again raised from 25 ° C. to 300 ° C. at a rate of 10 ° C./min. The temperature of the step transition portion was the glass transition temperature, and the peak top of the endothermic peak was the glass transition temperature and melting point, respectively.

Example 1
As the thermoplastic resin A, polyethylene terephthalate (PET) having a melting point of 258 ° C. was used. Further, as the thermoplastic resin B, polyethylene terephthalate (PE / SPG15T / CHDC20) copolymerized with 20 mol% of cyclohexanedimethanol which is an amorphous resin having no melting point and 15 mol% of spiroglycol was used. 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 added. It added so that it might become 10 wt% with respect to the resin composition which comprises B layer which has the plastic resin B as a main component. The prepared thermoplastic resin A and thermoplastic resin B were respectively put into two single-screw extruders, and the former was melted at 280 ° C. and the latter was 260 ° C. and kneaded. Next, after 5 sheets of FSS type leaf disk filters are passed through each, 5 layers are stacked alternately in the thickness direction with a stacking ratio of 0.5 while being combined with a feed block with 5 slits while measuring with a gear pump. It was set as the laminated body made. Here, the slit length was designed to be stepped, and the intervals were all constant. The obtained laminate was composed of three thermoplastic resin A layers and two thermoplastic resin B layers, which were alternately laminated in the thickness direction. After feeding the laminate to a T-die and forming it into a sheet, it was rapidly cooled and solidified on a casting drum whose surface temperature was maintained at 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire, and an unstretched laminate A cast film was obtained.

After heating the obtained laminated cast film with a roll group set at 100 ° C., the film was stretched 3.3 times in the longitudinal direction of the film while rapidly heating from both sides of the film with a radiation heater between 100 mm in the stretching section length. Then it was once cooled. Subsequently, corona discharge treatment was applied to both surfaces of this laminated uniaxially stretched film in the air, the wetting tension of the base film was set to 55 mN / m, and the treated surfaces on both surfaces of the film (# 4 metabar became an easy slipping layer). A water-based coating containing vinyl acetate / acrylic resin containing 3 wt% of colloidal silica with a particle size of 100 nm is coated (hereinafter, “coating” means the above-mentioned content)), transparent, easy slipping, easy An adhesive layer was formed.

The laminated uniaxially stretched film was guided to a tenter, preheated with hot air of 90 ° C., and stretched 3.3 times in the film width direction at a temperature of 140 ° C. The stretching speed and temperature here were constant. The stretched biaxially stretched film is directly heat treated in a tenter with hot air of 220 ° C., then subjected to a 2% relaxation treatment in the width direction under the same temperature conditions, and then wound to obtain a laminated film. It was. The obtained laminated film exhibited physical properties as shown in Table 1. The thickness of the laminated film was 30 μm, and the light transmittance at wavelengths of 410 nm and 440 nm satisfied the target values of 18% and 88%, respectively, due to the absorption effect of the added ultraviolet absorber. Although the thickness was slightly thick and the UV absorber content was 10 wt%, the haze was slightly high, but the visibility was good when mounted on a display. Moreover, although the haze value fluctuation amount in the 85 ° C. and 85% RH accelerated moist heat resistance test was 1.7%, which was a relatively high value, it was not a fluctuation amount that deteriorated the visibility when the display was mounted.

(Comparative Example 1)
In Example 1, a film was prepared in the same manner without adding an ultraviolet absorber to the B layer mainly composed of the thermoplastic resin B. Although a colorless and transparent laminated film was obtained, since it did not have the ability to cut light in the ultraviolet region, ultraviolet rays were transmitted when mounted on a display, and deterioration of contents such as a polarizer was remarkably confirmed. The film was not suitable as a display member for the purpose of protecting the contents from external ultraviolet rays.

(Comparative Example 2)
Example 1 is the same as Example 1 except that two different thermoplastic resins are laminated in a feed block with three slits, and a laminated film in which three layers are laminated alternately with a lamination ratio of 0.5. Thus, a laminated film was obtained. The obtained laminated film achieved the light transmittance at wavelengths of 410 nm and 440 nm because the absorption performance by the ultraviolet absorber was equivalent to that of Example 1. On the other hand, the haze value variation in the accelerated moist heat resistance test was very high, and the whitening of the laminated film was confirmed by visual observation, which was not suitable for display applications requiring high transparency.

(Example 2)
An acrylic resin having a melting point of 230 ° C. is added as the thermoplastic resin A, and the triazine-based ultraviolet absorber described in Example 1 is added as the thermoplastic resin B so as to be 10 wt% with respect to the entire resin composition constituting the laminated film. Acrylic resin B having a melting point of 210 ° C. mixed with acrylic elastic particles was used. The prepared thermoplastic resin A and thermoplastic resin B were respectively fed into two single-screw extruders, and the former was melted at 270 ° C. and the latter at 250 ° C. It was set as the laminated body by which five layers were laminated | stacked alternately in the thickness direction of 5. The laminate was cooled so that both surfaces were completely adhered to a stainless steel polishing roll (70 ° C.) to obtain an acrylic resin film having a film thickness of 30 μm. From the point that the obtained laminated film is an amorphous resin, the UV absorber added in the accelerated heat resistance test is likely to precipitate on the surface, and although it looks somewhat whitish compared to Example 1, it is suitable for display applications. It had usable optical performance.

(Example 3)
In Example 1, a thermoplastic resin was laminated with a feed block having 501 slits, and a laminated film having a thickness of 30 μm was obtained by alternately stacking 501 layers in the thickness direction with a lamination ratio of 1.0. The obtained laminated film has 251 layers of A layers and 250 layers of B layers, which are alternately laminated in the thickness direction, and shows that the laminated layer thickness distribution has two inclined structures. This was confirmed by observation. The inclined structure had a layer thickness distribution that linearly decreased from the center toward the opposite side of the film after the layer thickness increased linearly from one side of the film toward the center of the film. The ultraviolet absorber added to the thermoplastic resin B uses the same triazine-based ultraviolet absorber as in Example 1, and the concentration of addition is relative to the resin composition constituting the B layer mainly composed of the thermoplastic resin B. It was 10 wt%. The stretching conditions of the film were performed by the method described in Example 1. The obtained laminated film had reflection performance associated with the laminated structure, but because the thickness was a little thin, the long wavelength end of the reflection wavelength range was up to about 390 nm, and the cut of wavelength 410 nm was added with an ultraviolet absorber. It was an embodiment depending on the concentration. Since a laminated structure is used, no volatilization of the UV absorber from the die was confirmed, and an increase in Δhaze in the accelerated moist heat resistance test was suppressed, and the performance usable for display applications was obtained.

Example 4
In Example 3, a laminated film was obtained in the same manner as in Example 3 except that the laminated film had a thickness of 31 μm and the addition concentration of the ultraviolet absorber added to the thermoplastic resin B was 3 wt%. By increasing the thickness by 1 μm, the long wavelength end of the reflection wavelength range is shifted to about 405 nm, the light transmittance at a wavelength of 410 nm shows 6%, and even if the additive concentration of the UV absorber is reduced, the target is achieved. Was made. Although a slightly purple color due to reflection was strongly confirmed, the visibility of the display was not significantly deteriorated, and the performance was suitably usable.

(Comparative Example 3)
In Example 3, a laminated film was obtained in the same manner as in Example 3 except that the addition concentration of the ultraviolet absorber added to the thermoplastic resin B was 3 wt%. Due to poor ultraviolet absorption performance, the light transmittance at a wavelength of 410 nm was 62%. This laminated film was mounted on a display and tested for content protection by UV irradiation. However, since the content was confirmed to be deteriorated, it was not suitable for the purpose of protecting the content of the display. It was.

(Example 5)
In Example 4, a laminated film was obtained in the same manner as in Example 4 except that the thickness was 30.5 μm. The long wavelength end of the reflection wavelength range was shifted to about 397 nm, and the light transmittance at a wavelength of 410 nm was 48%. Although it was inferior in cutability at a wavelength of 410 nm as compared with Example 4, it was sufficiently effective in protecting the deterioration of contents due to being incorporated in the display. In addition, since the reflection wavelength range was shifted by a short wavelength, the reflection hue was considerably suppressed, and almost no purple reflection was observed when the display was mounted.

(Example 6)
In Example 1, a resin was laminated with a feed block having 251 slits, and a laminated film having a thickness of 12 μm was obtained by alternately laminating 251 layers in the thickness direction with a lamination ratio of 0.5. The obtained laminated film is composed of 126 layers of A and 125 layers of B, which are alternately laminated in the thickness direction, and that the laminated layer thickness distribution has two inclined structures. This was confirmed by observation. In addition, the addition prescription of the ultraviolet absorber and the stretching conditions of the film were performed by the method described in Example 1. The obtained laminated film has a long wavelength end of the reflection wavelength range of about 395 nm, the average light reflectance at a wavelength of 380 to 410 nm is as low as about 12%, and the wavelength of 410 nm is increased by increasing the concentration of the ultraviolet absorber. As a result, the cutting performance was satisfied. Since it has a multilayer structure, the result that the bleed-out phenomenon from a nozzle | cap | die was suppressed was obtained. The Δhaze after the accelerated moist heat resistance test was about 1.3%, which was low compared to Example 1, and was suitable as a film for display purposes. Further, the bending rigidity was as low as 3.6 × 10 ^−9, and even when the bending resistance test was performed, there was no scratch or crease, and it was sufficiently applicable to display applications requiring bending.

(Comparative Example 4)
In Example 6, instead of the triazine-based UV absorber, a benzotriazole-based UV absorber having a molecular weight of 650 g / mol (2,2′-methylenebis (4- (1,1,3,3-tetramethylbutyl)- Example 6 except that 6- (2H-benzotriazol-2-yl) phenol) was added at 10 wt% with respect to the resin composition constituting the B layer mainly composed of the thermoplastic resin B. A laminated film was obtained in the same manner as described above, and the haze value fluctuation amount after the accelerated moist heat resistance test was remarkable, and whitening was strongly confirmed by visual observation, and the laminated film was not suitable for display applications.

(Example 7)
In Example 6, a laminated film was obtained in the same manner as in Example 6 except that the thickness was 12.3 μm. By slightly increasing the thickness, the long wavelength end of the reflection wavelength range shifted to around 405 nm, and it was confirmed that sufficient cutability was obtained by reflection even when the concentration of the UV absorber was lowered. The other performance was the same as in Example 6 and was a film suitable for display applications.

(Example 8)
In Example 6, as an additive formulation of the ultraviolet absorber, the triazine-based ultraviolet absorber having a molecular weight of 700 g / mol described in Example 1 was added so as to be 9.0 wt% with respect to the thermoplastic resin B. The film stretching conditions were the same as those described in Example 6. Since the effect of multiple interference reflection was obtained because the number of laminated layers was 251, it was confirmed that even when the addition concentration was suppressed, the ultraviolet cut performance could be achieved as intended. It was confirmed that the amount of fluctuation in the haze value in the accelerated moist heat resistance test was also reduced as compared with Example 2 because the additive concentration was reduced.

Example 9
In Example 6, as a UV absorber to be added, a triazine-based UV absorber having a molecular weight of 510 g / mol (2- (4,6-diphenyl-s-triazin-2-yl) -5- (2- (2- (2- Ethylhexanoyloxy) ethoxy) phenol) is 2.0 wt% with respect to the resin composition constituting the B layer mainly composed of the thermoplastic resin B, and a triazine type having a molecular weight of 700 g / mol described in Example 1 A laminated film was obtained in the same manner except that the ultraviolet absorber was added to 7.0 wt% with respect to the resin composition constituting the B layer mainly composed of the thermoplastic resin B. The former triazine-based ultraviolet absorber has a maximum wavelength at 285 nm, and the light-cutting performance in the ultraviolet region is increased, so that it is possible to cut ultraviolet rays more strongly. It was suitable as an optical film for display for protecting contents from the above.

(Example 10)
In Example 6, as an ultraviolet absorber to be added, a benzotriazole 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) is 2.0 wt% with respect to the resin composition constituting the B layer mainly composed of the thermoplastic resin B, and the molecular weight described in Example 1 is 700 g / mol. A laminated film was obtained in the same manner as in Example 6 except that the triazine-based ultraviolet absorber was 7.0 wt% with respect to the resin composition constituting the B layer mainly composed of the thermoplastic resin B. The former benzotriazole-based UV absorber has a maximum wavelength at 346 nm, and as in Example 9, the light transmittance in the UV region is lower than that in Examples 6 and 7, and UV blocking is achieved. When the benzotriazole system was used, the haze fluctuation amount in the accelerated moisture and heat resistance test tended to be slightly higher, but it had sufficient performance as an optical film for displays. .

(Example 11)
In Example 10, the thickness of the laminated film was 12.3 μm, and among the UV absorbers added to the thermoplastic resin B, the addition concentration of benzotriazole UV absorber was 0.7 wt%, and the triazine UV absorber A laminated film was obtained in the same manner as in Example 10 except that the addition concentration of was changed to 2.3 wt%. By combining the effect of reflection due to the laminated structure and the effect of absorption of the UV absorber, it was possible to reduce the concentration of the UV absorber added, and the Δ haze in the accelerated moist heat resistance test could be greatly reduced. .

Example 12
In Example 6, as the UV absorber to be added, a benzotriazole UV absorber (2- (5-chloro-2H-benzotriazol-2-yl) -6-tert-butyl-4-ylate having a molecular weight of 315 g / mol) was added. Methylphenol) is 4.0 wt% with respect to the resin composition constituting the B layer mainly composed of the thermoplastic resin B, and a triazine ultraviolet absorber having a molecular weight of 700 g / mol described in Example 1 is heated. A laminated film was formed in the same manner as in Example 6 except that 4.0 wt% was added to the resin composition constituting the B layer containing the plastic resin B as a main component. The benzotriazole-based UV absorber used in this example was excellent in UV-cutting ability on the long wavelength side, and reached the target even when the concentration of the triazine-based UV absorber was reduced. However, compared with Example 6, the loss of transmittance in the ultraviolet region on the low wavelength side occurred, and the haze value in the reliability test slightly increased. The visibility when mounted on a display was good, and it was a highly transparent laminated film suitable for an optical film for display.

(Example 13)
In Example 6, as an ultraviolet absorber to be added, an azomethine ultraviolet absorber having a molecular weight of 250 g / mol and a maximum absorption wavelength of 378 nm is used for the resin composition constituting the B layer mainly composed of the thermoplastic resin B. 1.0 wt% of the triazine-based ultraviolet absorber having a molecular weight of 700 g / mol described in Example 1 is added to the resin composition constituting the B layer mainly composed of the thermoplastic resin B. A laminated film was obtained in the same manner as in Example 6 except that. The former azomethine compound mainly absorbs visible light in the short wavelength region, and the latter triazine ultraviolet absorber absorbs in the ultraviolet region. It was. The optical performance was as shown in Table 1, and it was a highly transparent laminated film suitable for display applications.

(Example 14)
In Example 6, polyethylene terephthalate is used as the thermoplastic resin A, and the triazine-based ultraviolet absorber having a molecular weight of 700 g / mol described in Example 1 is used for the resin composition containing the thermoplastic resin A as a main component. A resin composition that constitutes a B layer mainly composed of the thermoplastic resin B and the triazine-based ultraviolet absorber described in Example 1 in the thermoplastic resin B. A laminated film was obtained in the same manner as in Example 6 except that it was added so as to be 6.0 wt% and that the lamination ratio was designed to be 1.0. Even when a small amount of about 2.0 wt% was added to the A layer composed of the thermoplastic resin A containing the outermost layer, no significant haze increase was confirmed in the accelerated moist heat resistance test. Also, compared with Example 6 added only to the B layer, the amount of ultraviolet absorption increases due to the effect of increasing the optical path length associated with the multiple interference reflection between the layers. The effect of was obtained.

(Example 15)
In Example 6, an indole system having a maximum wavelength of 393 nm as a dye having a maximum wavelength in the visible light short wavelength region exceeding 380 nm and not exceeding 430 nm in the thermoplastic resin B without adding an ultraviolet absorber. Implementation was performed except that the dye was added so as to be 4.0 wt% with respect to the resin composition constituting the B layer mainly composed of the thermoplastic resin B, and the lamination ratio was 1.0. A laminated film was obtained in the same manner as in Example 6. Although the ultraviolet cut in the wavelength region of 300 to 380 nm is weakened as compared with the previous examples, the target cut performance was shown by utilizing the reflection effect because the ultraviolet absorber was not added. Even when mounted as a display application, it was confirmed that the liquid crystal and the light emitting layer were not significantly deteriorated and could be suitably used.

(Example 16)
In Example 15, a naphthalimide dye having a maximum wavelength of 382 nm as a dye having the maximum wavelength in the visible light short wavelength region of more than 380 nm and not more than 430 nm is used as a main component of the thermoplastic resin B. A laminated film was obtained in the same manner as in Example 15 except that it was added so as to be 3.5 wt% with respect to the resin composition constituting the layer. The naphthalimide-based dye is very excellent in sharp cutability at a wavelength of 410 nm, and exhibits very good cutability except that there is some loss of transmittance at 300 to 380 nm.

(Example 17)
In Example 15, the thermoplastic resin B has the maximum of the triazine-based ultraviolet absorber having a molecular weight of 700 g / mol described in Example 1 as the ultraviolet absorber in the visible light short wavelength region exceeding 380 nm and not exceeding 430 nm. A laminated film was obtained in the same manner as in Example 15 except that the indole dye used in Example 15 as a dye having a wavelength was added to 2.0 wt% and 1.0 wt%, respectively. By combining two kinds of absorbents that cut different wavelength regions, it was possible to effectively achieve a wavelength cut at a low concentration.

(Example 18)
In Example 17, as an ultraviolet absorber to be added to the thermoplastic resin B, a triazine ultraviolet absorber having a molecular weight of 700 g / mol described in Example 1 and a benzotriazole ultraviolet having a molecular weight of 650 g / mol described in Example 7 were used. In the same manner except that the absorbent is mixed and added to 1.4 wt% and 0.6 wt% with respect to the resin composition constituting the B layer mainly composed of the thermoplastic resin B, respectively. A laminated film was obtained. Although the obtained laminated film had a slightly high haze value fluctuation amount in the long-term reliability test as compared with Example 17, it had sufficient performance suitable as a film for display applications.

(Example 19)
In Example 18, a laminated film was obtained in the same manner as in Example 18 except that the thickness of the laminated film was 12.2 μm and the addition concentration of the indole dye added to the thermoplastic resin B was reduced to 0.5 wt%. It was. Since the obtained laminated film has the long wavelength end of the reflection wavelength range in the vicinity of 400 nm, it was possible to effectively achieve the intended UV-cutting property by combining the absorption of the dye and the reflection by the laminated structure.

(Example 20)
In Example 17, the same procedure was used except that the addition concentration of the triazine-based ultraviolet absorber added to the thermoplastic resin B was reduced to 1.0 wt% and the addition concentration of the indole dye was increased to 2.0 wt%. A laminated film was obtained. Although the light transmittance in the ultraviolet region was higher than that in the above-described Examples, it was a laminated film that sufficiently achieved the target cut property.

(Example 21)
In Example 17, the addition concentration of the triazine-based ultraviolet absorber is 5.0 wt%, and further has a maximum wavelength at a wavelength of 420 nm as a dye having a maximum wavelength in the visible light short wavelength region of more than 380 nm and not more than 430 nm. A laminated film was obtained in the same manner as in Example 17 using a phthalocyanine dye. The phthalocyanine colorant can sharply cut light only in the vicinity of a wavelength of 400 to 440 nm, and the light transmittance at a wavelength of 440 nm was barely satisfied with the target value of 80%. On the other hand, it was necessary to increase the additive concentration of the ultraviolet absorber in order to cut ultraviolet rays up to a wavelength of 400 nm. However, the haze fluctuation amount in the reliability test was not particularly significant, and it was suitable for display applications. A film was obtained.

(Example 22)
By applying a hard coat agent added with an indole dye having a maximum wavelength in the short wavelength region of visible light exceeding 380 nm and not more than 430 nm on the laminated film prepared in Example 17, hard A laminated sheet having a coat layer laminated thereon was obtained. After the indole dye is dissolved in methyl ethyl ketone, it is added to the hard coat main agent so as to be 4.0 wt% with respect to the resin composition constituting the hard coat layer, and finally the total solid content concentration is 30%. A hard coat agent was prepared by adding a methyl ethyl ketone solvent. The hard coat was applied to one side of the laminated film so as to have a thickness of 2 μm. After coating, the film was dried in an oven at 80 ° C. for 1 to 2 minutes to volatilize the methyl ethyl ketone solvent, and then irradiated with ultraviolet rays so that the cumulative amount of ultraviolet rays was 180 mJ / cm ² to obtain the desired laminated sheet. The resulting laminated sheet has a highly crosslinkable hard coat layer located on the outermost surface, so that precipitation of oligomers and additives in the laminated film is reduced, which is faster than in Example 17 where no hard coat is applied. Fluctuation in haze value during the wet heat resistance test was reduced. Moreover, the dimensional stability was also good, and it was suitable for display applications.

(Example 23)
In Example 22, an anthraquinone dye having a maximum absorption wavelength of 406 nm as a dye having a maximum wavelength that exceeds 380 nm and is 430 nm or less added to the hard coat agent is used as a hard coat layer. A laminated sheet was obtained in the same manner as in Example 17 except that it was added so as to be 10 wt% with respect to the resin composition to be constituted. Although the anthraquinone dye is slightly poor in absorption performance and there is concern about surface precipitation due to the addition of a high concentration, no significant whitening after the long-term reliability test has been confirmed, and it has long-term stability and is suitable for display applications I was able to judge that

(Example 24)
In Example 22, in addition to a dye having a maximum wavelength that is maximum in the visible light short wavelength region of more than 380 nm and less than or equal to 430 nm, hard coat agent, LA-72 manufactured by Adeka as a hindered amine light stabilizer, A laminated sheet was obtained in the same manner as in Example 22 except that 0.5 wt% was added to the resin composition constituting the hard coat layer. By adding the light stabilizer, it was possible to prevent deterioration of the contents at the time of display mounting longer than in Example 22.

(Example 25)
In Example 24, in addition to the light stabilizer, a phosphorus / phenolic mixed antioxidant A-612 made by Adeka as an antioxidant, and a nickel quencher SEESORB 612NH made by Cypro Kasei as a singlet oxygen quencher, It added so that it might become 0.3 wt% and 4 wt% with respect to the resin composition which comprises a hard-coat layer, respectively. Further, a laminated sheet was obtained in the same manner as in Example 24 except that toluene was used instead of methyl ethyl ketone as a solvent and drying was performed in a hot air oven at 110 ° C. for 3 minutes after applying the hard coating agent. By using a light stabilizer, an antioxidant, and a singlet oxygen quencher in combination, the long-term stability of the indole dye with respect to light irradiation is improved from that in Example 24. The laminate sheet had the longest light resistance. The basic optical performance was equivalent to that in Example 24.

(Example 26)
In Example 24, as the ultraviolet absorber added to the thermoplastic resin B, the benzotriazole ultraviolet absorber having a molecular weight of 650 g / mol and the triazine ultraviolet absorber having a molecular weight of 700 g / mol used in Example 18 were respectively thermoplastic. The laminated sheet was formed in the same manner except that 0.6 wt% and 1.4 wt% were added to the resin composition constituting the B layer containing resin B as the main component and the thickness of the laminated film was 12.2 μm. Obtained. Although the haze fluctuation amount after a long-term reliability test has been confirmed to be slightly higher due to the highly precipitateable benzotriazole-based UV absorber, it does not deteriorate visibility during display mounting and can be used as a display application. It was a laminated sheet.

(Example 27)
In Example 22, a laminated film having a thickness of 12.2 μm was prepared, and the maximum wavelength used in Example 22 was as a pigment having a maximum wavelength exceeding 380 nm and in the visible light short wavelength region of 430 nm or less. Except for adding 393 nm indole dye and anthraquinone dye having a maximum wavelength of 406 nm used in Example 23 to the resin composition constituting the hard coat layer, 3.0 wt% and 6.0 wt%, respectively. In the same manner as in Example 17, a laminated sheet was obtained. The combination of the dyes improved the cut property at 410 nm and the light transmittance at 440 nm, and achieved the most preferable sharp cut property among the examples so far. Moreover, the amount of haze fluctuation after the reliability test was small, and it was suitable as a film for display applications.

(Example 28)
In Example 4, a laminated film was prepared with an addition concentration of the triazine-based ultraviolet absorber being 1.0 wt%. An indole dye-added hard coat layer containing a light stabilizer was provided on one side of the surface of the obtained laminated film in the same manner as in Example 24 to form a laminated sheet. Reflection of the wavelength in the ultraviolet region can be further strengthened, the result of improved cut performance in the ultraviolet region, and a laminated sheet having the performance that can withstand long-term ultraviolet irradiation. Due to the presence of the multilayer laminated structure and the hard coat layer, the precipitation of the UV absorber and / or the dye having the maximum maximum wavelength in the visible light short wavelength region exceeding 380 nm and 430 nm or less is considerably small, and the amount of fluctuation in haze is large. The result was suppressed.

(Example 29)
In Example 5, the addition concentration of the triazine-based ultraviolet absorber was 1.4 wt%, and the benzotriazole-based ultraviolet absorber having a molecular weight of 650 g / mol used in Example 10 was further mixed with the thermoplastic resin B as a main component. 0.6 wt% was added to the resin composition constituting the layer to obtain a laminated film. On the obtained laminated film, a hard coat agent added with a benzylidine-based dye having a maximum wavelength of 381 nm as a dye having a maximum wavelength in a short wavelength region of visible light shorter than 430 nm and exceeding 380 nm is applied on the film. The laminated sheet on which the hard coat layer was laminated was obtained by applying to. Specifically, after dissolving the benzylidine dye in methyl ethyl ketone, it was added to 1.0 wt% with respect to the resin composition constituting the hard coat layer, and the hindered amine light stability used in Example 24 was further added. A hard coat agent was prepared by adding 0.5 wt% of the agent, and finally adding a methyl ethyl ketone solvent so that the total solid concentration was 30%. The hard coat layer was applied to one side of the laminated film so as to have a thickness of 5 μm. After coating, obtained after evaporation of the methyl ethyl ketone solvent and dried for 1-2 minutes in an oven at 80 ° C., UV irradiation integrated amount is then cured by UV irradiation so that 180 mJ / cm ^2, the desired laminated sheet It was. The obtained laminated sheet was suppressed in the reflected hue, and also satisfied the target light transmittance, and was able to prevent deterioration of the contents for a long time even when mounted on a display. In addition, the hard coat thickness was large, and the Δhaze in the accelerated moisture and heat resistance test could be greatly suppressed to 0.5, so that it had a property that it could be sufficiently used as an optical film for display applications.

(Example 30)
In Example 26, 4.0 wt% of the indole dye used in Example 17 was added as a dye having the maximum wavelength in the short wavelength region of visible light exceeding 380 nm and not more than 430 nm, and was implemented as an antioxidant. A laminated sheet was obtained in the same manner as in Example 26, except that 0.3 wt% of the phosphorus / phenol mixed antioxidant A-612 used in Example 25 was added. While the basic performance of the laminated sheet was the same as that of Example 26, the content protection by ultraviolet irradiation lasted longer.

(Example 31)
In Example 30, the addition concentration of the indole dye was 2.0 wt%, the addition concentrations of the light stabilizer and the antioxidant were 0.25 wt% and 0.15 wt%, respectively, and the hard coat layer was applied to both sides of the laminated film. A laminated sheet was obtained in the same manner as in Example 30 except that. By laminating the hard coat layers on both sides, almost no haze-up in the accelerated moist heat resistance test was confirmed, and it became suitable as a film used for displays for a longer period.

(Example 32)
In Example 30, a pigment-free hard coat layer was provided on one side of the laminated film so as to have a thickness of 2 μm. Further, an acrylic optical adhesive to which 0.4 wt% of indole dye was added was applied to the opposite surface of the hard coat layer of the laminated film so as to have a thickness of 20 μm by bar coating. After the adhesive was applied, it was dried in an oven at 100 ° C. for 2 to 3 minutes, and further subjected to an aging treatment in a hot air oven at 40 ° C. for 2 days to obtain a laminated sheet with an adhesive. The optical performance of the laminated sheet with pressure-sensitive adhesive was the same as in Example 30. When it was bonded to the display, the dye was positioned in the adhesive layer inside the display from the laminated film, so that the light stability of the dye was further increased by receiving the UV-cutting performance of the laminated sheet. From the viewpoint of protecting the display contents over a long period of time, it became the most preferable among all the examples.

Since the laminated film of the present invention is excellent in ultraviolet cut ability and visible light transmittance for sharply cutting light having a wavelength of 410 nm or less, visibility can be improved and deterioration due to ultraviolet rays can be prevented. Therefore, the laminated film of the present invention can be suitably used as a film incorporated in an image display device such as a liquid crystal display. In addition, UV protection is required, for example, window films for building materials and automotive applications, steel film laminating films for signboards for industrial materials, and photolithographic process / release films for electronic devices. It can be suitably used for films for food, medicine and agriculture.

Claims

A film in which five or more layers (layer B) mainly composed of a thermoplastic resin A and layers (layer B) composed mainly of a thermoplastic resin B different from the thermoplastic resin A are laminated, A laminated film having a light transmittance of 60% or less at a wavelength of 410 nm and a light transmittance of 80% or more at a wavelength of 440 nm.
The laminated film according to claim 1, wherein the maximum value of light transmittance at a wavelength of 300 to 380 nm is 10% or less.
The laminated film according to claim 1, wherein the average light reflectance at a wavelength of 380 to 410 nm is 20% or more.
The A layer and / or the B layer contain an ultraviolet absorber and / or a dye having a maximum wavelength that is the maximum in the visible light short wavelength region of more than 380 nm and not more than 430 nm. Laminated film.
The laminated film according to claim 4, wherein the ultraviolet absorber and / or the pigment having a maximum wavelength that is maximum in the visible light short wavelength region exceeding 380 nm and not exceeding 430 nm has a triazine skeleton.
The dye having the maximum wavelength in the short wavelength range of visible light shorter than 380 nm and longer than 430 nm is at least one skeleton selected from azomethine, indole, quinone, naphthalimide, phthalocyanine, and benzylidine The laminated film according to claim 4 or 5, which has
The sum of the content of the ultraviolet absorber contained in a layer of the laminated film and the pigment having the maximum wavelength exceeding 380 nm and the maximum wavelength in the visible light short wavelength region of 430 nm or less is Mn [wt%], and the layer of the layer When the thickness is defined as Tn [μm], Σ (Mn × Tn) obtained by adding the product of the sum of the contents and the layer thickness for all layers of the laminated film is 50 [wt% · μm] or less. The laminated film according to any one of claims 4 to 6.
The laminated film according to any one of claims 1 to 7, comprising a hindered amine light stabilizer in an amount of 0.01 wt% to 1 wt% based on the total weight of the film.
The laminated film according to any one of claims 1 to 8, wherein 51 layers or more of A layers and B layers are alternately laminated.
The laminated film according to any one of claims 1 to 9, wherein the thermoplastic resin A and the thermoplastic resin B are polyester resins.
The laminated film according to any one of claims 1 to 10, wherein a bending rigidity per unit length is 1.0 × 10 -7 [N · m 2 ] or less.
The laminated film according to any one of claims 1 to 11, wherein the Δhaze when treated at 85 ° C and 85% RH for 250 hours is 1.0% or less.
A laminated sheet comprising a hard coat layer (C layer) comprising a curable resin C as a main component on at least one surface of the laminated film according to any one of claims 1 to 12.
A laminated film comprising the laminated film according to any one of claims 1 to 12 and an adhesive layer comprising an ultraviolet absorber and / or a dye having a maximum absorption exceeding 380 nm and in the visible light short wavelength region of 430 nm or less. Sheet.
A laminated sheet comprising the laminated sheet according to claim 13 and an adhesive layer comprising an ultraviolet absorber and / or a dye having a maximum wavelength exceeding 380 nm and in the visible light short wavelength region of 430 nm or less.
The laminated film according to any one of claims 1 to 12, or the laminated sheet according to any one of claims 13 to 15, which is used for display applications.