CN112424653B

CN112424653B - Optical film, film laminate, and display unit

Info

Publication number: CN112424653B
Application number: CN201980047437.1A
Authority: CN
Inventors: 川浪敬太
Original assignee: Mitsubishi Chemical Corp
Current assignee: Mitsubishi Chemical Corp
Priority date: 2018-08-07
Filing date: 2019-08-05
Publication date: 2023-06-23
Anticipated expiration: 2039-08-05
Also published as: KR20210040075A; CN112424653A; WO2020031932A1

Abstract

When incorporated in an image display device in combination with an LED light source, the following optical film has been proposed as an optical film capable of uniformizing the luminous intensity in the visible light region, uniformizing the color of the display screen, and preventing the reduction of the luminanceCharacterized in that it is a polyester film containing a dye and/or pigment, the haze of the film is 6% or less, the light transmittance at 450nm is 4% or less, the light transmittance at 550nm is 20% or more, and the color tone (b) ^* ) The value is 50 or more.

Description

Optical film, film laminate, and display unit

Technical Field

The present invention relates to an optical film and a film laminate suitable for use in combination with an LED light source.

Background

Polyester films have been used in various industrial applications, and their uses have been expanding and diversified, taking full advantage of their excellent heat resistance, water resistance, chemical resistance, mechanical strength, dimensional stability, and the like.

In recent years, in information terminal devices such as mobile phones and smart phones, the mounting rate of LED light sources has increased as the lifetime of the light sources has increased. The emission spectrum of a white LED light source (a type of emitting yellow phosphor by a blue LED) generally used in an information terminal device generally has a spectrum with a strong emission intensity around 450 nm. In the visible light region (400 nm to 720 nm), when the emission spectrum of the LED light source is taken as 100 as shown in fig. 1, the emission intensity of the spectrum around 450nm, particularly in the bright wavelength region (500 nm to 600 nm), is perceived as about 50 or less, and a large variation is exhibited, which is characterized as a bright line.

As a polyester film used in combination with such an LED light source, for example, patent document 1 discloses a polyester film for protecting a screen using an LED as a light source, in which a deviation rψ60 of a maximum value of a variation ψ of an amplitude ratio of measurement wavelengths 235 to 255nm, which is measured using an ellipsometer M-2000D manufactured by Woollam corporation, is 0.10 or more and 5.00 or less.

Patent document 2 discloses a laminated polyester film for protecting a screen or the like using an LED as a light source, which has no color unevenness, excellent surface quality, and excellent optical transparency, and which has a polyester layer made of a polyester resin and a polyester layer made of a polyester resin different from the polyester layer, wherein 30 layers or more are alternately laminated in the thickness direction, and the lamination interface roughness between the polyester layers is 0.2nm or more and 6.0nm or less.

In addition, as an optical film containing a dye and/or a pigment, for example, patent document 3 discloses an optical film including: a polarizing film comprising a polyolefin and a dichroic dye, a 1 st photo-alignment film located on one side of the polarizing film, and a 1 st liquid crystal layer located on one side of the 1 st photo-alignment film, wherein the polarizing film, the 1 st photo-alignment film, and the 1 st liquid crystal layer have a structure in which they are bonded to each other.

Patent document 4 discloses an optical film comprising a transparent substrate and, provided thereon, at least a hard coat layer containing at least a binder matrix and a yellow pigment, wherein the hard coat layer has a transmittance of light at a wavelength of 440nm of 80% or less.

Patent document 5 discloses an optical film comprising fine particles of vanadium dioxide having thermochromic properties, which contains a dye or pigment that absorbs light in the wavelength range of 650 to 700nm, and which has an average light absorption rate in the wavelength range of 30 to 85% at 23 ℃.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2017-132990

Patent document 2: japanese patent application laid-open No. 2017-43083

Patent document 3: japanese patent laid-open publication No. 2017-58659

Patent document 4: japanese patent laid-open publication No. 2017-3884

Patent document 5: international publication WO2016/158620

Non-patent literature

Non-patent document 1: effect of light technical information journal "light edge" No.10 1997, chapter 2 information equipment and light source

Disclosure of Invention

Problems to be solved by the invention

When an image, for example, a digital image is read by using a display screen, it is preferable that the light source (for example, sunlight or the like) has a continuous spectrum of light emission intensity without variation in different wavelength ranges as a spectral characteristic required for the image, and has a strong light emission intensity as a whole (non-patent document 1).

However, in the case of using an image represented by an LED light source, as described above, since the emission spectrum of the LED light source is weak in the emission intensity on the long wavelength side (500 nm or more) in the visible light region, it is difficult to read the image.

In order to solve such a problem, if an attempt is made to increase the emission intensity on the long wavelength side (for example, 500nm or more) of the visible light region as a whole with respect to the emission spectrum itself of the LED light source, the emission intensity in the region where the LED light source originally has a sufficient emission intensity, that is, in the region near 450nm is rather decreased. Thus, it is not easy to uniformly increase the light emission intensity in the entire visible light region (400 nm to 720 nm).

The variation in the emission intensity is also considered to be a cause of variation in the color of the display screen. For example, when the light emission intensity at 450nm is higher than the required intensity, the color of the display screen tends to be blue.

However, in a Liquid Crystal Display (LCD) mounted in an information terminal device such as a mobile phone or a smart phone, a touch panel system such as an impedance film system or a capacitive system is generally used for inputting information.

The touch screen system generally uses transparent electrodes as constituent members. The transparent electrode is constituted, for example, by: a transparent conductive layer made of a metal oxide such as indium oxide (ITO) or zinc oxide (ZnO) containing tin oxide is laminated on a glass or transparent resin film substrate.

Such a transparent electrode tends to be colored yellow or brown as a result of a decrease in transmittance in the short wavelength region of visible light caused by reflection and absorption of the repeated metal oxide layer. Therefore, in the case of a liquid crystal display device disposed under a touch panel, the color may be unexpected. Accordingly, development of transparent conductive films focusing on other conductive materials such as metal nanoparticles and conductive polymers has been intensively studied, but the current situation is insufficient to solve the above-mentioned problems.

The present invention provides a novel optical film and a novel film laminate, wherein the optical film is incorporated in an image display device in combination with an LED light source, can uniformize the emission intensity of light supplied to a display in the visible light region, can realize the uniformity of the color of a display screen, can prevent the reduction of brightness, and can suppress the color change of the display screen accompanying the deterioration of a transparent electrode with time when the display unit is constituted by combining with the transparent electrode.

Solution for solving the problem

The present invention provides an optical film comprising a polyester film containing a dye and/or pigment, having a haze of 6% or less, a light transmittance of 450nm of 4% or less, a light transmittance of 550nm of 20% or more, and a color tone (b) ^* ) The value is 50 or more.

The present invention also provides a film laminate comprising a resin film laminated on one side of the optical film of the present invention via an adhesive layer, wherein the film laminate has a film haze of 15% or less, a light transmittance of 1% or less at 450nm, a light transmittance of 15% to 30% at 550nm, and a color tone (b) ^* ) The value is 70 or more.

The present invention provides a film laminate comprising a resin film laminated on one side of an optical film comprising a polyester film containing a dye and/or a pigment via an adhesive layer, wherein the film laminate has a film haze of 15% or less, a light transmittance of 1% or less at 450nm, a light transmittance of 15% to 30% at 550nm, and a color tone (b) ^* ) The value is 70 or more.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the optical film or the film laminate according to the present invention, when incorporated in an image display device in combination with an LED light source, light supplied to a display can be enhanced in a wavelength region where the light emission intensity of the light emitted from the LED light source is insufficient, that is, in a light emission intensity of 550nm, without impeding the light emission performance (light transmittance) of the light emitted from the LED light source, and therefore, uniformity of the light emission intensity can be achieved without lowering the luminance. That is, the light emitted from the LED light source originally has variations in transmittance in each wavelength region, and by using the optical film or the film laminate according to the present invention in combination, variations in transmittance at each wavelength can be eliminated and made uniform, and therefore uniformity of display screen color can be achieved, and improvement of brightness can also be achieved. Therefore, when a (digital) image is read using light in the visible light range around 550nm, for example, the (digital) image is not blurred as in the conventional case, and a clearer (digital) image can be read.

Further, on the premise that the optical film according to the present invention or the film laminate according to the present invention is mounted as a constituent member of a display, in the future, with the time degradation of the constituent member, for example, with the time degradation of the transparent electrode as described above, color change of the display screen due to discoloration is predicted, and the types and amounts of dyes and pigments are adjusted, so that the color tone of the optical film according to the present invention or the film laminate according to the present invention is adjusted in advance to the same level as the color tone after the change, whereby the color tone after the change of the constituent member can be the same color tone, and as a result, the color change of the display screen can be made inconspicuous. Therefore, it is possible to prevent the color from being unexpected, which is different from the color that the original display screen should have.

Drawings

Fig. 1 is a graph showing an example of the emission intensity of each wavelength of a normal LED light source (type of yellow fluorescent material emitted by a blue LED) (horizontal axis: measurement wavelength (nm), vertical axis: relative emission intensity (%)).

Fig. 2 is a diagram schematically showing an example of the configuration of a display unit and an example of the light propagation method in the configuration example of the display unit according to an embodiment of the present invention.

Fig. 3 is a diagram schematically showing an example of a light propagation mode in a display unit in a thin film laminate structure according to an example of the embodiment of the present invention.

Fig. 4 is a diagram showing an example of a spectrum of an optical polyimide film (horizontal axis: measurement wavelength (nm), vertical axis: transmittance (%)) as an example of a typical pattern of a spectrum of a conventional optical film.

Detailed Description

The present invention will be described below based on examples. However, the present invention is not limited to the embodiments described below.

Optical film-

An example of an optical film according to an embodiment of the present invention (referred to as the "present optical film") is a polyester film containing a dye and/or a pigment.

In the present invention, the term "polyester film" means a film having a polyester resin layer, the term "polyester resin layer" means a layer containing polyester as a main component resin, and the term "main component resin" means a resin having the highest mass ratio among resins constituting the layer.

< haze of film >

In the present optical film, the haze of the film is preferably 6% or less, more preferably 4% or less, 3% or less, and particularly 2% or less, for the purpose of optical use. The lower limit of the haze of the film is not limited, and may be 0% or more, and usually about 0.5% or more.

< hue >

The present optical film has a color tone (b) from the viewpoint of preventing a change in color tone due to the deterioration of the constituent members with time ^* The value) is preferably 50 or more, more preferably 60 or more, 70 or more, particularly 80 or more. The upper limit is preferably about 98.

Tone (b) ^* ) A film having a value within the above range isAt least a yellow film is visually presented. Generally, if the polyester film does not contain any substance that causes coloration, the color tone (b) ^* ) The value is about-5 to +3.

In order to make the color tone (b) of the optical film ^* ) In the above range, for example, a large amount of yellow dye may be blended, the basic color tone may be set, and other colors of dye or pigment may be appropriately combined. However, the method is not limited thereto.

< light transmittance >

For the present optical film, it is preferable that: the light transmittance at a wavelength of 450nm is 4% or less, and the light transmittance at a wavelength of 550nm is 20% or more.

As described above, the emission spectrum of the LED light source generally has a spectrum having a strong emission intensity in the vicinity of 450nm, and has a characteristic that the emission intensity in the vicinity of 550nm is significantly lower than the emission intensity in the spectrum in the vicinity of 450 nm. Therefore, when the optical film has the light transmittance in the wavelength region, the light emission intensity of the light emitted from the LED light source can be enhanced in a wavelength region where the light emission intensity is insufficient without blocking the light emission performance (light transmittance) of the light emitted from the LED light source when the optical film is combined with the LED light source and incorporated into the image display device, and therefore, uniformity of the light emission intensity can be achieved without lowering the luminance.

From the above-mentioned viewpoints, the optical film preferably has a light transmittance at a wavelength of 450nm of 4% or less, more preferably 3% or less and 2% or less.

The lower limit of the light transmittance of the optical film at a wavelength of 450nm is not limited, but is usually 0% or more, preferably 0.01% or more.

On the other hand, the light transmittance at a wavelength of 550nm is required to be 20% or more, and more preferably 25% or less, 30% or more, or 80% or less.

Further, from the viewpoint of color uniformity of the display screen, the transmittance is preferably increased as the wavelength is higher at least in a region from the short wavelength (400 nm) side to the long wavelength (720 nm) side of the visible light region. More specifically, it is preferable that the transmittance at each measurement wavelength of (1) 400nm, (2) 550nm, (3) 650nm, and (4) 720nm is increased as the wavelength is located on the higher wavelength side.

Further, it is preferable that any 1 or more of the following conditions (5) to (8) is satisfied, more preferably any 2 or more of the conditions (5) to (8) is satisfied, still more preferably any 3 or more of the conditions (5) to (8) is satisfied, and particularly, all the conditions (5) to (8) are satisfied.

(5) From the viewpoint of color uniformity of the display screen, the maximum value of the light transmittance in the measurement wavelength range of 400nm to 480nm is preferably 3% or less, more preferably 2% or less and 1% or less.

(6) From the viewpoint of color uniformity of the display screen, the maximum value of the light transmittance in the measurement wavelength range of 500nm to 600nm is preferably 30 to 85%, more preferably 40% or less or 80% or less, and further preferably 50% or more or 70% or less.

(7) From the viewpoint of color uniformity of the display screen, the maximum value of the light transmittance in the measurement wavelength range of 610nm to 680nm is preferably 51 to 70%, more preferably 55% or more and 70% or less, and further preferably 60% or more and 70% or less.

(8) The maximum value of the light transmittance in the measurement wavelength range of 700nm to 720nm is preferably 61 to 80%, more preferably 65% or less, 70% or more, or 80% or less, from the viewpoint of color uniformity of the display screen.

In the present optical film, as described above, in order to control the light transmittance in each specific wavelength region, it is preferable to control the type of the dye and/or pigment contained in the polyester film by adjusting the type. Particularly preferably, at least 2 or more, 3 or more, and 4 or more of the dyes selected from yellow dye, red dye, blue dye, and brown dye are suitably selected and contained in the polyester film.

< film Structure >

The present optical film may be a single-layer polyester film composed of a polyester resin layer, or may be a multilayer polyester film composed of 2 or more polyester resin layers. In this case, 3 or more layers may be used.

As an example of the case where the present optical film is a polyester film composed of 3 polyester resin layers, for the purpose of effectively improving various characteristics, there are: the raw materials of the polyester resin layer as the surface layer and the polyester resin layer as the intermediate layer were changed to form a 3-layer structure example.

Further, as an example of a polyester film composed of 3 polyester resin layers in the same manner, there is given: only the polyester resin layer constituting the intermediate layer contains a dye and/or pigment, and the two surface layers are examples of polyester resin layers substantially free of the dye and/or pigment. With the above configuration, bleeding of the dye and/or pigment can be prevented.

In addition, as an example of a polyester film composed of 3 polyester resin layers in the same manner, there is an example in which the polyester resin layers constituting the intermediate layer and the two surface layers contain a pigment.

In the present invention, the term "surface layer" refers to a layer constituting an exposed surface of a film having a surface layer, and the other layers are referred to as an intermediate layer.

(functional layer)

The optical film may have a functional layer (X) as a film surface layer on one side.

Further, as the film surface layer on one side or the other side, a structure having a functional layer (Y) different from the functional layer (X) may be employed. For example, the following constitution may be adopted: the functional layer (X) is provided as one film surface layer, and the functional layer (Y) is provided as the other film surface layer.

The functional layer is a layer having various functions, and examples thereof include an easy-to-adhere layer, an antistatic layer, and the like, which are described in order. However, the types of the functional layers are not limited to these, and examples thereof include an anti-blocking layer, a release layer, a flame retardant layer, a hard coat layer, a print layer, and the like.

Specific examples of the structure include the following: the surface layer of one side of the optical film is provided with an easy-to-adhere layer, and the surface layer of the other side is provided with an antistatic layer.

The easy-to-adhere layer and the antistatic layer are as described later.

< polyester >

The polyester which becomes the main component resin of each polyester resin layer in the optical film may be a homo-polyester or a co-polyester.

In the case of a homo-polyester, a polyester obtained by polycondensing an aromatic dicarboxylic acid with an aliphatic diol is preferable.

Examples of the aromatic dicarboxylic acid include terephthalic acid and 2, 6-naphthalene dicarboxylic acid, and examples of the aliphatic diol include ethylene glycol, diethylene glycol and 1, 4-cyclohexane dimethanol.

As such a representative polyester, polyethylene terephthalate and the like can be exemplified.

The dicarboxylic acid component of the copolyester may be one or two or more of isophthalic acid, phthalic acid, terephthalic acid, 2, 6-naphthalene dicarboxylic acid, adipic acid, sebacic acid, and the like, and the diol component may be one or two or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 4-cyclohexanedimethanol, neopentyl glycol, and the like.

As such representative polyesters, polyethylene naphthalate (PEN) and the like may be exemplified.

The intrinsic viscosity of the polyester which is the main component resin of each polyester resin layer in the optical film is usually preferably 0.3 to 0.9dl/g, more preferably 0.4dl/g or more or 0.8dl/g or less, and still more preferably 0.5dl/g or more or 0.8dl/g or less.

The method for measuring the intrinsic viscosity is described in examples below.

The preferable range of intrinsic viscosity of the present optical film itself and the preferable range of intrinsic viscosity of each polyester resin layer are the same as the above ranges.

< dye/pigment >

In the case where the optical film is formed of a single layer of a polyester resin layer, the polyester resin layer preferably contains a dye and/or a pigment. On the other hand, in the case of a multilayer structure composed of 2 or more polyester resin layers, it is preferable that at least any one of the polyester resin layers contains a dye and/or a pigment, and among them, it is preferable that the polyester resin layer constituting the intermediate layer contains a dye and/or a pigment. In particular, in the case of using a dye, from the viewpoint of reducing bleeding of the dye, it is preferable that the intermediate layer contains the dye and the surface layer contains substantially no dye.

The term "substantially free" means not intentionally included, and this also means that the inclusion is also included inevitably.

(dye)

The dye is preferably used in consideration of heat resistance, dispersibility, and the like sufficient to withstand the temperature at the time of producing the present optical film. From the above viewpoints, dyes of anthraquinone type, phthalocyanine type, viol type, isoquinoline type and the like are preferable in terms of chemical structure.

Disperse dyes, oil-soluble dyes are suitable in dyeing formulations.

Even a substance generally classified as a pigment can be used as a dye in the present invention as long as it is dissolved in the molten polyester as described above. Specific examples thereof include complex salt dyes of phthalocyanine groups and other metal ions such as copper, cobalt, nickel, zinc, and chromium.

From the viewpoint of controlling the light transmittance in each specific wavelength region as described above, it is preferable to use at least 2 or more of yellow dye, red dye, blue dye and brown dye in combination, more preferably 3 or more dyes in combination, and particularly more preferably 4 dyes in combination.

In the present invention, the above-mentioned classification of dyes is based on the classification of the British dye dyeing society or the "dye index" of the American society of fiber chemistry/dyeing technology.

As the combination of 2 kinds of dyes, there may be mentioned a combination of a yellow dye and a red dye, a yellow dye and a blue dye, a yellow dye and a brown dye, a red dye and a blue dye, a red dye and a brown dye, and a blue dye and a brown dye.

Further, as a combination of 3 kinds of dyes, there are exemplified a combination of a yellow dye and a red dye and a blue dye, a combination of a yellow dye and a red dye and a brown dye, a combination of a yellow dye and a blue dye and a brown dye, and a combination of a red dye and a blue dye and a brown dye.

The content of the dye in each layer (total amount of 2 or more) is preferably 0.01 to 10 mass%, more preferably 0.05 mass% or more and 7 mass% or less, and 0.1 mass% or more and 5 mass% or less.

In the case where 2 or more dyes are used in combination as described above, a large amount of yellow dye may be blended as an example thereof from the viewpoint of securing a desired color tone, and the dye or pigment of another color may be suitably combined to provide a basic color tone.

Specifically, the dye content in the film is preferably adjusted so that (formula 1) the yellow dye is not less than the red dye+the blue dye+the brown dye (% by mass).

Further, the dye content in the film is more preferably adjusted so as to satisfy (formula 2) yellow dye ∈ (red dye+blue dye+brown dye) ×10 (mass%).

In the above-mentioned (formula 1) and (formula 2), the yellow dye, the red dye, the blue dye, and the brown dye show the content ratio (mass%) of each dye in the film.

(pigment)

The pigment is not particularly limited in the type when imparting a hue to the optical film, and may be appropriately selected according to the desired characteristics. For example, particles of titanium dioxide, barium sulfate, calcium carbonate, carbon black, and the like can be exemplified. These may be surface-treated with oxides of aluminum, silicon, zinc, or the like from the viewpoint of improving dispersibility in polyesters, weather resistance, or the like.

Examples of the inorganic coloring pigment include calcium sulfate, asbestos, kaolin, magnesium carbonate, alumina white, zinc white, lead white, alkali sulfate, lithopone, zinc sulfide, antimony white, ferroferric oxide, barium chromate, cadmium yellow, titanium yellow, iron oxide yellow, loess, zinc ferrite, realgar, cyanamide lead, calcium plumbate, red chrome yellow, molybdenum chrome red, red lead, brown clay, red lead, cinnabar, cadmium red, cadmium mercury red, stibium, molybdenum orange red, chrome yellow, manganese violet, ultramarine, prussian blue, sky blue, cyanosis, cobalt green, cobalt violet, zinc yellow, cobalt green, chrome green, zinc green, chromium oxide, emerald green, zinc silicate, zinc cadmium sulfide, calcium sulfide, strontium sulfide, and calcium tungstate.

Further, organic coloring pigments can be used, and specific examples thereof include azo coloring pigments, phthalocyanine pigments, acid dye lakes, basic dye lakes, condensed polycyclic coloring pigments, nitroso pigments, alizarin lakes, metal complex salt azomethine pigments, nigrosine pigments, basic blue pigments, and the like.

Examples of the azo coloring pigment include monoazo lake pigments, monoazo pigments, disazo pigments, condensed azo pigments, metal complex azo pigments, and examples of the condensed polycyclic pigments include anthraquinone pigments, indigo pigments, viol pigments, perylene pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, isoindoline pigments, phthalocyanine pigments, dioxazine pigments, and anthraquinone pigments.

The average particle diameter of the coloring pigment is preferably 5.0 μm or less, more preferably 0.01 μm or more and 4.0 μm or less, and further preferably 0.05 μm or more and 3.0 μm or less.

< other ingredients >

The polyester resin layer may be compounded with particles as needed mainly for the purpose of imparting slidability, in addition to the above-mentioned polyester, dye or pigment.

In addition, conventionally known antistatic agents, weather-proofing agents, light-shading agents, antioxidants, heat stabilizers, lubricants, fluorescent brighteners and the like may be added as required.

Further, depending on the application, an ultraviolet absorber, particularly a benzoxazinone-based ultraviolet absorber, may be contained. For example, a pigment such as a white pigment may be added to improve visibility.

In the case where the pigment is in the form of particles, the pigment may be repeated with particles as other components, but in the present invention, the pigment is regarded as a pigment as long as the pigment contributes to the hue (influence) of the optical film. In this case, the particles as the pigment may also have the function of particles as other components.

(particles)

As described above, the polyester resin layer may be compounded with particles mainly for the purpose of imparting slidability.

The type of the particles is not particularly limited as long as the particles can impart slidability, and specific examples thereof include silica, titanium oxide, zeolite, silicon nitride, boron nitride, diatomaceous earth, alumina, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, calcium phosphate, lithium phosphate, magnesium phosphate, lithium fluoride, silicon oxide, kaolin, talc, carbon black, and crosslinked polymer fine powder. However, the present invention is not limited to these.

On the other hand, the shape of the particles is not particularly limited, and any of spherical, block-like, rod-like, flat and the like may be used.

In addition, the hardness, specific gravity, and the like thereof are also not particularly limited. These series of particles may be used in combination of 2 or more kinds as required.

The average particle diameter of the particles is usually 5 μm or less, preferably in the range of 0.01 to 3. Mu.m.

Further, the content of the particles in the polyester resin layer is usually 5% by mass or less, preferably 0.005 to 4% by mass, and more preferably 0.005 to 2% by mass, based on the polyester resin layer containing the particles.

< method for containing dye, pigment and particle >

The method for containing the particles and the colorant in the polyester is not particularly limited. For example, the following methods can be mentioned: a method of adding in the polymerization step; and a method of kneading the pellets and the dye into a master batch using an extruder.

< thickness >

The thickness of the optical film is preferably 10 to 250. Mu.m, more preferably 25 μm or more and 125 μm or less, and 38 μm or more and 100 μm or less.

< manufacturing method >

Next, an example of the method for producing the optical film will be described.

Here, as an example of a preferred embodiment of the present optical film, a method for producing an optical film comprising 3 polyester resin layers, wherein the intermediate layer contains only a dye and/or a pigment, and the surface layer does not contain a dye and a pigment will be described. However, the present invention is not limited to such a configuration.

A polyester resin composition for forming an intermediate layer containing a predetermined amount of a dye and/or a pigment and, if necessary, a predetermined amount of other materials such as particles is prepared, and a polyester resin composition for forming a surface layer containing no dye and pigment is prepared, and the respective compositions are fed to different melt extrusion apparatuses and heated to a temperature equal to or higher than the melting point of the respective polymers to melt the respective compositions. Next, the melted polymer was laminated in a laminar flow joint in an extrusion tube head and extruded from a slit-shaped die, and quenched and solidified on a rotary cooling drum to a temperature equal to or lower than the glass transition temperature, thereby obtaining a substantially amorphous unstretched sheet. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and it is preferable to use an electrostatic encryption method and/or a liquid coating and sealing method.

The optical film may be a non-stretched film (sheet), or may be a stretched film. Among them, from the viewpoints of heat resistance, physical properties, and the like, a stretched film is preferable.

In addition, in the case of a stretched film, a uniaxially stretched film or a biaxially stretched film may be used.

Specifically, the stretching conditions are described, and it is preferable that the unstretched sheet is stretched at 70 to 120℃for 2 to 6 times in the machine direction to form a uniaxially stretched film, and then stretched at 90 to 160℃for 2 to 6 times in the transverse direction to form a biaxially stretched film, and heat treatment is performed at 150 to 250℃for 1 to 600 seconds. Further, in this case, there may be mentioned: a method of relaxing by 15% or less in the longitudinal direction and/or the transverse direction in the highest temperature zone of the heat treatment and/or the cooling zone of the heat treatment outlet.

Further, if necessary, a re-longitudinal stretching and a re-transverse stretching may be applied.

< functional layer >

Next, the adhesive layer and the antistatic layer will be described in order for various functional layers that can be provided as the functional layer (X) or (Y).

< easy adhesion layer >

The easy-to-adhere layer is a layer for improving adhesion to various optical members, and may be provided as needed.

The composition for forming an easy-to-bond layer is preferably a layer containing at least one of a compound having a carbon-carbon double bond and a urethane resin.

(Compound having a carbon-carbon double bond)

Examples of the compound having a carbon-carbon double bond include compounds having a monofunctional (meth) acrylate group, a difunctional (meth) acrylate group, a polyfunctional (meth) acrylate group, a vinyl group, an allyl group, and the like.

The label of "(meth) acrylate compound" means "acrylate compound and/or methacrylate compound".

The monofunctional (meth) acrylate is not particularly limited. Examples thereof include methyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate and other (meth) acrylates, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate and other (meth) alkyl acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, ethoxypropyl (meth) acrylate and other (meth) alkyl acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate and other aromatic (meth) acrylates such as diaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate and other (meth) acrylates containing amino groups, methoxyethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, phenylphenol ethylene oxide modified (meth) acrylates and other ethylene oxide modified (meth) acrylates, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate and the like.

The difunctional (meth) acrylate is not particularly limited. Examples thereof include alkylene glycol di (meth) acrylates such as 1, 4-butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1, 9-nonanediol di (meth) acrylate, tricyclodecane dimethylol di (meth) acrylate, bisphenol modified di (meth) acrylates such as bisphenol a ethylene oxide modified di (meth) acrylate and bisphenol F ethylene oxide modified di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, urethane di (meth) acrylate, and epoxy di (meth) acrylate.

The polyfunctional (meth) acrylate is not particularly limited. Examples thereof include urethane acrylates such as dipentaerythritol hexa (meth) acrylate, pentaerythritol tetra (meth) acrylate, bis (trimethylol) propane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylol methane ethylene oxide modified tetra (meth) acrylate, isocyanuric acid ethylene oxide modified tri (meth) acrylate, epsilon-caprolactone modified tri (acryloyloxyethyl) isocyanurate, and the like, pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, and dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer.

These monofunctional (meth) acrylate group-having compounds, difunctional (meth) acrylate group-having compounds, polyfunctional (meth) acrylate group-having compounds, vinyl group-having compounds and allyl group-having compounds may be used singly or in combination of two or more.

Among these (meth) acrylate compounds, difunctional (meth) acrylates and polyfunctional (meth) acrylates are preferable from the viewpoint of improving adhesion, and among them, polyfunctional (meth) acrylates are particularly preferable.

When the (meth) acrylate compound is used, the ratio of the carbon-carbon double bond to the (meth) acrylate compound is preferably 3% by mass or more, more preferably 5% by mass or more. The upper limit thereof is usually 40 mass%.

(urethane resin)

The urethane resin may be a polymer compound having a urethane bond in a molecule, and may be a polymer compound obtained by reacting a polyol with an isocyanate.

Examples of the polyol include polycarbonate polyols, polyester polyols, polyether polyols, polyolefin polyols, and acrylic polyols, and these may be used alone or in combination. From the viewpoint of improving adhesion, a polycarbonate polyol or a polyester polyol is preferable, and a polycarbonate polyol is more preferable.

The polycarbonate polyol constituting the urethane resin includes a polycarbonate polyol obtained by dealcoholization reaction of a polyol and a carbonate compound.

In this case, examples of the polyhydric alcohol include ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, trimethylolpropane, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, 1, 7-heptanediol, 1, 8-octanediol, 1, 9-nonanediol, 1, 10-decanediol, neopentyl glycol, 3-methyl-1, 5-pentanediol, and 3, 3-dimethylolheptane.

Examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and ethylene carbonate, and examples of the polycarbonate polyol obtained by these reactions include poly (1, 6-hexylene) carbonate and poly (3-methyl-1, 5-pentylene) carbonate.

Examples of the polyester polyol constituting the urethane resin include polyesters obtained by reacting polycarboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or anhydrides thereof with polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 2-methyl-1, 3-propanediol, 1, 5-pentanediol, neopentyl glycol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, 2-methyl-2, 4-pentanediol, 2-methyl-2-propyl-1, 3-propanediol, 1, 8-octanediol, 2, 4-trimethyl-1, 3-pentanediol, 2-ethyl-1, 3-hexanediol, 2, 5-dimethyl-2, 5-hexanediol, 1, 9-nonanediol, 2-methyl-1, 8-octanediol, 2-ethyl-1, 3-propanediol, 2-methyl-1, 3-propanediol, 2-ethyl-1, 3-propanediol, 2-hydroxy-caprolactone, bisphenol lactone, etc.), and the like, and having a polyhydric alcohol, such as a polyester having a bisphenol, a lactone, a bis-hydroxy-benzyl lactone, and a bis-lactone.

Examples of the polyether polyol constituting the urethane resin include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene glycol, and polyhexamethylene glycol.

Examples of the polyisocyanates constituting the urethane resin include aromatic diisocyanates such as toluene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, benzene diisocyanate, naphthalene diisocyanate, and tolylene diisocyanate, aliphatic diisocyanates having an aromatic ring such as α, α, α ', α' -tetramethylxylylene diisocyanate, aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylenebis (4-cyclohexyl isocyanate), dicyclohexylmethane diisocyanate, and alicyclic diisocyanates such as isopropylene dicyclohexyl diisocyanate. These may be used singly or in combination, and these polyisocyanate compounds may be dimers, trimers represented by isocyanurate rings, or polymers thereof.

Among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are more preferable than aromatic isocyanates from the viewpoints of improving adhesion to active energy ray-curable coatings and preventing yellowing by ultraviolet rays.

The urethane resin may be synthesized using a chain extender, but there is no particular limitation as long as it has 2 reactive groups reactive with isocyanate groups, and a chain extender having 2 hydroxyl groups or amino groups may be mainly used in general.

Examples of the chain extender having 2 hydroxyl groups include aliphatic diols such as ethylene glycol, propylene glycol, butanediol and pentanediol, aromatic diols such as xylylene glycol and dihydroxyethoxybenzene, and diols such as neopentyl glycol and neopentyl glycol hydroxypivalate.

Examples of the chain extender having 2 amino groups include aromatic diamines such as toluene diamine, xylylenediamine and diphenylmethane diamine, alicyclic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, 2-dimethyl-1, 3-propane diamine, 2-methyl-1, 5-pentanediamine, trimethylhexamethylenediamine, 2-butyl-2-ethyl-1, 5-pentanediamine, 1, 8-octanediamine, 1, 9-nonanediamine, 1, 10-decanediamine, 1-amino-3-aminomethyl-3, 5-trimethylcyclohexane, dicyclohexylmethane diamine, isopropylcyclohexyl-4, 4' -diamine, 1, 4-diaminocyclohexane, 1, 3-diaminomethylcyclohexane and isophorone diamine.

The urethane resin may be a solvent as a medium, or water as a medium.

In the case of an aqueous urethane resin, there are: in order to disperse or dissolve the urethane resin in water, a forced emulsification type using an emulsifier is used; self-emulsifying or water-soluble urethane resins having hydrophilic groups introduced therein. In particular, the self-emulsifying type in which an ionomer is formed by introducing an ionic group into the skeleton of a urethane resin is preferable because the liquid is excellent in storage stability, water resistance, transparency, and adhesion of the obtained coating layer.

Examples of the ionic group to be introduced include various groups such as carboxyl group, sulfonic acid, phosphoric acid, phosphonic acid, and quaternary ammonium salt, and among these, carboxyl group is preferable.

As a method for introducing a carboxyl group into a urethane resin, various methods can be employed in each stage of polymerization. For example, in synthesizing the prepolymer, the following method may be employed: a method in which a resin having a carboxyl group is used as a copolymerization component; a method of using a component having a carboxyl group as one component such as a polyol, a polyisocyanate, a chain extender and the like. Particularly preferred are: a method of introducing a desired amount of carboxyl groups by the amount of the component added using a diol containing carboxyl groups. For example, a diol used for polymerization of a urethane resin such as dimethylolpropionic acid, dimethylolbutyric acid, bis- (2-hydroxyethyl) propionic acid, and bis- (2-hydroxyethyl) butyric acid may be copolymerized.

The carboxyl group is preferably in the form of a salt neutralized with ammonia, an amine, an alkali metal, an inorganic base, or the like. Particularly preferred are ammonia, trimethylamine, triethylamine. The urethane resin may be prepared by using a carboxyl group from which a neutralizing agent has been removed in a drying step of a coating liquid as a crosslinking reaction point by another crosslinking agent. This makes it possible to further improve the durability, water resistance, blocking resistance, and the like of the obtained adhesive layer.

(adhesive Polymer)

The composition for forming an easy-to-bond layer preferably contains a binder polymer in addition to the urethane resin or the compound having a carbon-carbon double bond, from the viewpoint of improving the coating appearance, transparency, and adhesion.

The binder polymer means: according to the safety evaluation scheme of a polymer compound (sponsored by the chemical society of 11 th year of 60), a polymer compound having a number average molecular weight (Mn) of 1000 or more as measured by Gel Permeation Chromatography (GPC) and having film forming properties may be used as a polymer compound having a number average molecular weight (Mn) of 1000 or more as a necessary condition.

Specific examples of the binder polymer include polyester resins, polyethylene (polyvinyl alcohol, polyvinyl chloride, chlorinated ethylene-vinyl acetate copolymer, etc.), polyalkylene glycols, polyalkylene imines, methylcellulose, hydroxycellulose, starches, etc., and these may be used alone or in combination of 2 or more of them.

The polyester resin as the binder polymer may be any resin composed of a polycarboxylic acid and a polyhydroxy compound as described below as the main constituent components.

As the polycarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 4' -diphenyldicarboxylic acid, 2, 5-naphthalenedicarboxylic acid, 1, 5-naphthalenedicarboxylic acid and 2, 6-naphthalenedicarboxylic acid, 2, 7-naphthalenedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, potassium terephthalic acid-2-sulfonate, sodium isophthalic acid-5-sulfonate, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, succinic acid, trimellitic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, parahydroxybenzoic acid, monopotassium trimellitate, ester-forming derivatives thereof, and the like can be used.

As the polyhydric hydroxyl compound, ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 4-butanediol, 1, 6-hexanediol, 2-methyl-1, 5-pentanediol, neopentyl glycol, 1, 4-cyclohexanedimethanol, p-xylylene glycol, ethylene glycol-modified bisphenol A, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (oxytetramethylene) glycol, dimethylolpropionic acid, glycerol, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropionate, and the like can be used. From these polycarboxylic acids and polyhydric hydroxyl compounds, 1 or more may be appropriately selected, respectively, and a polyester resin may be synthesized by polycondensation reaction by a conventional method.

The polyvinyl alcohol as the binder polymer may be any compound having a polyvinyl alcohol site. For example, conventionally known polyvinyl alcohol may be used, including modified compounds obtained by partially acetalizing polyvinyl alcohol, butyrally polymerizing polyvinyl alcohol, and the like.

The polymerization degree of the polyvinyl alcohol is not particularly limited, and is preferably 100 or more, more preferably 300 or more or 40000 or less, and 500 or more or 10000 or less. By satisfying the above range, the water resistance of the coating layer can be ensured.

The saponification degree of the polyvinyl alcohol is not particularly limited, but is preferably 70 mol% or more, more preferably 80 mol% or more or 99.9 mol% or less, 86 mol% or more or 97 mol% or less, and 95 mol% or less.

The content of the binder polymer in the composition for forming an easy-to-bond layer is preferably 30% by mass or more, more preferably 40% by mass or more, and still more preferably 50% by mass or more.

On the other hand, from the viewpoint of obtaining a good coating film strength, the content of the binder polymer in the composition for forming an easy-to-bond layer is preferably 90 mass% or less, more preferably 80 mass% or less, and further preferably 75 mass% or less.

(crosslinking agent)

The composition for forming an easy-to-bond layer further contains a crosslinking agent, thereby improving the crosslinking degree of the easy-to-bond layer obtained after curing and improving the adhesiveness and durability thereof.

As the crosslinking agent, an oxazoline compound, an isocyanate compound, an epoxy compound, a melamine compound, and a carbodiimide compound are preferably used. Among them, from the viewpoint of improving the adhesion, at least 1 of an oxazoline compound or an isocyanate compound is more preferably used.

The oxazoline compound used as the crosslinking agent is a compound having an oxazoline group in a molecule, and particularly preferably a polymer containing an oxazoline group, and can be produced by polymerizing a monomer containing an addition polymerizable oxazoline group alone or with other monomers. Examples of the addition polymerizable oxazolinyl group-containing monomer include: 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, and the like, and a mixture of 1 or 2 or more of these may be used. Among them, 2-isopropenyl-2-oxazoline is also industrially easily available and is suitable. The other monomer is not limited as long as it is copolymerizable with the addition polymerizable oxazoline group-containing monomer, and examples thereof include (meth) acrylic esters such as alkyl (meth) acrylates (as alkyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, cyclohexyl); unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrenesulfonic acid and salts thereof (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated amides such as (meth) acrylamide, N-alkyl (meth) acrylamide, and N, N-dialkyl (meth) acrylamide (as alkyl, methyl, ethyl, N-propyl, isopropyl, N-butyl, isobutyl, t-butyl, 2-ethylhexyl, and cyclohexyl); vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; alpha-olefins such as ethylene and propylene; halogen-containing alpha, beta-unsaturated monomers such as vinyl chloride and vinylidene chloride; and an α, β -unsaturated aromatic monomer such as styrene and α -methylstyrene, and 1 or 2 or more kinds of these monomers may be used.

From the viewpoint of improving adhesion, the oxazoline group amount of the oxazoline compound is preferably 0.5 to 10mmol/g, more preferably 1mmol/g or more or 9mmol/g or less, 3mmol/g or more or 8mmol/g or less, and 4mmol/g or more or 6mmol/g or less.

The isocyanate compound used for the crosslinking agent is a compound having an isocyanate derivative structure represented by isocyanate or blocked isocyanate. Examples of the isocyanate include aromatic isocyanates such as toluene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, benzene diisocyanate and naphthalene diisocyanate, aliphatic isocyanates having an aromatic ring such as α, α, α ', α' -tetramethylxylylene diisocyanate, aliphatic isocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate and hexamethylene diisocyanate, and alicyclic isocyanates such as cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylenebis (4-cyclohexyl isocyanate) and isopropylidene dicyclohexyl diisocyanate.

Examples of the isocyanate include polymers and derivatives such as biurets, isocyanurates, uretdiones, and carbodiimide-modified products of these isocyanates. These may be used alone or in combination. Among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are suitable as measures against yellowing by ultraviolet irradiation.

When the blocked isocyanate is used, examples of the blocking agent include phenol compounds such as bisulfite, phenol, cresol, and ethylphenol, alcohol compounds such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol, and ethanol, active methylene compounds such as methyl isobutyrylacetate, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, and acetylacetone, thiol compounds such as butyl mercaptan, and dodecyl mercaptan, lactam compounds such as epsilon-caprolactam, and delta-valerolactam, amine compounds such as diphenyl aniline, and ethyleneimine, amide compounds such as acetanilide, and acetamides, and oxime compounds such as formaldehyde, acetaldehyde oxime, acetoxime, methyl ethyl ketoxime, and cyclohexanone oxime, and the like, and these compounds may be used singly or in combination.

The isocyanate compound may be used alone, or may be used in combination with various polymers. From the viewpoint of improving dispersibility and crosslinkability of the isocyanate compound, a mixture or a combination with a polyester resin or a urethane resin is preferably used.

The epoxy compound used as the crosslinking agent is a compound having an epoxy group in the molecule, and examples thereof include condensates of epichlorohydrin with hydroxyl groups and amino groups such as ethylene glycol, polyethylene glycol, glycerin, polyglycerol, bisphenol a, and the like, and polyepoxide compounds, diepoxide compounds, monoepoxy compounds, glycidyl amine compounds, and the like. Examples of the polyepoxide include sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycidyl polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanate, glycerin polyglycidyl ether, and trimethylolpropane polyglycidyl ether, examples of the diglycidyl compound include neopentyl glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, resorcinol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polytetramethylene glycol diglycidyl ether, examples of the monoepoxy compound include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, and phenyl glycidyl ether, and examples of the glycidylamine compound include N, N' -tetraglycidyl-m-xylylenediamine, and 1, 3-bis (N, N-diglycidyl amino) cyclohexane. From the viewpoint of improving adhesion, polyether-based epoxy compounds are preferred.

Further, as the amount of the epoxy group, a trifunctional or higher polyfunctional polyepoxide is preferable as compared with the difunctional.

The above melamine compound used for the crosslinking agent is a compound having a melamine skeleton in the compound, and for example, a compound in which an alcohol is partially or completely etherified by reacting with an alkyl-alcoholized melamine derivative, and a mixture thereof can be used. As the alcohol used for etherification, methanol, ethanol, isopropanol, n-butanol, isobutanol, and the like can be suitably used.

The melamine compound may be any of a monomer or a dimer or more, or a mixture thereof may be used. Furthermore, a catalyst for improving the reactivity of the melamine compound may be used in combination with a type in which a part of melamine is co-condensed with urea or the like.

The carbodiimide compound used in the crosslinking agent is a compound having a carbodiimide structure, and preferably has 1 or more carbodiimide structures in the molecule, and more preferably has 2 or more polycarbodiimides in the molecule for better adhesion and the like.

The carbodiimide compound can be synthesized by a conventionally known technique, and a condensation reaction of a diisocyanate compound is generally used. The diisocyanate compound is not particularly limited, and any of aromatic and aliphatic compounds may be used, and specifically toluene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, benzene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, dicyclohexylmethane diisocyanate, and the like may be mentioned.

The content of the carbodiimide group contained in the carbodiimide compound is preferably 100 to 1000 in terms of a carbodiimide equivalent (weight [ g ] of the carbodiimide compound for imparting 1mol of a carbodiimide group), and more preferably 250 or 800 or less, 300 or 700 or less. When used in the above range, the durability of the coating film is improved.

In addition, a surfactant may be added to improve the water solubility and water dispersibility of the polycarbodiimide compound within a range that does not impair the gist of the present invention; hydrophilic monomers such as polyalkylene oxide, quaternary ammonium salt of dialkylaminoalcohol, and hydroxyalkylsulfonate are added.

In the case of containing the above-mentioned crosslinking component, a component for promoting crosslinking, for example, a crosslinking catalyst or the like may be used in combination.

When the easy-to-adhere layer is formed in this manner, it can be presumed that unreacted products of these crosslinking agents, compounds after reaction, or a mixture thereof are present in the easy-to-adhere layer.

The content of the crosslinking agent in the composition for forming an easy-to-bond layer is preferably 10 mass% or more, more preferably 20 mass% or more, and still more preferably 25 mass% or more, from the viewpoint of obtaining a good coating film strength after curing.

On the other hand, from the viewpoint of obtaining good adhesion to other functional layers such as an adhesive layer, the content of the crosslinking agent in the composition for forming an easy-to-adhere layer is preferably 70 mass% or less, more preferably 60 mass% or less, and even more preferably 50 mass% or less.

(containing the components)

The composition for forming an easy-to-adhere layer may further contain particles for improving slidability and blocking.

When the adhesive layer contains particles, the average particle diameter is preferably 1.0 μm or less, more preferably 0.5 μm or less and 0.2 μm or less, from the viewpoint of film transparency.

Examples of the particles contained in the easy-to-adhere layer include particles such as silica, alumina, kaolin, calcium carbonate, and organic particles.

The composition for forming an easy-to-bond layer may contain an antifoaming agent, a coating property improver, a thickener, an organic lubricant, an ultraviolet absorber, an antioxidant, a foaming agent, a dye, a pigment, and the like as necessary.

These additives may be used alone, or two or more kinds may be used in combination as required.

(method for Forming an easy-to-bond layer)

The composition for forming the easy-to-adhere layer may be applied by a conventionally known application method such as reverse gravure coating, direct gravure coating, roll coating, extrusion coating, bar coating, curtain coating, or the like.

The easy-to-adhere layer may be provided by, for example, in-line coating in which the film surface is treated in the film-forming step of the polyester film. However, the method is not limited to this method of formation.

By the case of an in-line coating setup, preference is given to: the polyester film is coated with a coating liquid having a solid content of about 0.1 to 50 mass% as an aqueous solution or aqueous dispersion.

In addition, a small amount of an organic solvent may be contained in the coating liquid for the purpose of improving dispersibility in water, improving film forming property, and the like, within a range not impairing the gist of the present invention. The number of organic solvents may be 1, or may be at least 2.

The conditions for drying and curing when forming the easy-to-adhere layer are not particularly limited, and for example, when the composition for forming the easy-to-adhere layer is provided by off-line coating, it is preferable to perform heat treatment at 80 to 200℃for 3 to 40 seconds, preferably at 100 to 180℃for 3 to 40 seconds as a standard.

On the other hand, when the composition for forming an easy-to-adhere layer is provided by in-line coating, it is usually preferable to perform the heat treatment at 70 to 280℃for 3 to 200 seconds as a standard.

In addition, either off-line coating or on-line coating, active energy radiation such as heat treatment or ultraviolet radiation may be used in combination as required.

The surface of the object surface on which the adhesive layer is formed may be subjected to a surface treatment such as corona treatment or plasma treatment.

(thickness)

The film thickness (after drying) of the adhesive layer is preferably 0.002 μm to 10.0. Mu.m, more preferably 0.005 μm or more and 5 μm or less, 0.01 μm or more and 2 μm or less, and 0.01 μm or more and 0.5 μm or less.

When the film thickness of the easy-to-adhere layer is in the above range, adhesion can be ensured, and deterioration of blocking, increase in haze, and the like can be suppressed.

< antistatic layer >

The antistatic layer may contain an electron conductive compound.

Examples of the electron-conductive organic compound include polyacetylene, polyphenylene, polyaniline, polypyrrole, polyisothiaindene, polythiophene, and the like. Among these, polythiophenes, namely, polymers obtained by copolymerizing thiophene or thiophene derivatives alone or may be mentioned.

The antistatic layer preferably contains, in addition to the electron conductive compound, 1 or more compounds selected from the group consisting of polyalkylene oxides, glycerin, polyglycerols, and alkylene oxide adducts with glycerin or polyglycerols, or derivatives thereof.

When the antistatic layer is formed by coating, for example, a surfactant, other binders, particles, an antifoaming agent, a coatability improver, a thickener, an antioxidant, an ultraviolet absorber, a foaming agent, a dye, a pigment, and the like may be used as the coating liquid. These additives may be used alone. Two or more kinds may be used in combination as needed.

The polyester film may be subjected to chemical treatment, corona discharge treatment, plasma treatment, or the like before coating.

In the case where the antistatic layer is provided, the surface resistivity of the optical film is preferably 1×10 ¹¹ Omega or less. Surface resistivity exceeding 1X 10 ¹¹ In the case of Ω, defects such as peeling electrification may occur in the processing step using an optical film.

< method of Forming functional layer >

As described in the item of each functional layer, the method for forming the functional layer is preferably formed by in-line coating in which the film surface is treated in the film forming step of the polyester film. However, off-line coating on the temporarily prepared film outside the system may also be employed.

In-line coating is a method of coating in a process for producing a polyester film, specifically, a method of coating at any stage from the time of melt extrusion of polyester to the time of thermal fixing after stretching and winding. Generally, the coating is applied to any of an unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, and a film after heat setting and before winding. The method of stretching in the transverse direction is not limited to the following, but is particularly advantageous in the sequential biaxial stretching, particularly after coating a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction). According to the above method, the film formation and the coating layer formation can be performed simultaneously, and therefore, there is an advantage in terms of manufacturing cost, and in addition, in order to perform stretching after coating, the thickness of the coating layer can be changed by the stretching ratio, and film coating can be performed more easily than off-line coating.

The present film laminate

The present film laminate according to an example of the embodiment of the present invention is preferably a film laminate in which a resin film is laminated on one side of the present optical film via an adhesive layer, the film laminate having a film haze of 15% or less, a light transmittance of 1% or less at 450nm, a light transmittance of 15% to 30% at 550nm, and a color tone (b) ^* ) The value is 70 or more.

< adhesive layer >

The film laminate is provided with: the optical film is constituted by laminating an adhesive layer on one side of the optical film and laminating a resin film on the adhesive layer.

The "adhesive layer" in the present film laminate is a layer made of a material having adhesiveness, and a known material can be used in the conventional art within a range not to impair the gist of the present invention. As one specific example, the case of using an acrylic adhesive will be described below.

The acrylic pressure-sensitive adhesive is an adhesive layer containing an acrylic polymer formed from an acrylic monomer as an essential monomer (monomer) component as a base polymer.

The acrylic polymer preferably contains an alkyl (meth) acrylate and/or an alkoxyalkyl (meth) acrylate having a linear or branched alkyl group as an essential monomer component, and more preferably contains an acrylic polymer mainly composed of a monomer component.

Further, the acrylic polymer is preferably an acrylic polymer comprising an alkyl (meth) acrylate having a linear or branched alkyl group and an alkoxyalkyl acrylate as essential monomer components.

< resin film >

In order to uniformize the color of the display screen, the color tone (b) of the resin film in the film laminate ^* ) The value is preferably 80 or more, more preferably 85 or more, particularly preferably 90 or more.

The light transmittance of the resin film is preferably 30 to 80%, more preferably 30 to 70%, and most preferably 35% or 65% or less. In particular, the light transmittance at a wavelength of 450nm is 1% or less, preferably 0.5% or less, more preferably 0.1% or less, particularly 0.05% or less, and the light transmittance at a wavelength of 550nm is preferably 30 to 80%.

In order to adjust the color tone (b) of the resin film ^* ) The value and the light transmittance are adjusted within the above ranges, and it is preferable to select a polymer skeleton constituting the resin film to be constituted by a specific structure.

The resin film in the film laminate can be used as a substrate for mounting an LED of an LED light source. Accordingly, the LED itself becomes a heat generating body with the light emission of the LED, and thus, it is preferable that the heat resistance is good. From the above viewpoints, the glass transition temperature of the resin film is preferably 200 ℃ or higher, more preferably 230 ℃ or higher and 250 ℃ or higher.

Satisfies the color tone (b) ^* ) Among the resin films having the values or glass transition temperature conditions, polyimide films are particularly preferable.

The polyimide film may be a commercially available polyimide film, or a polyimide film formed by a known method such as a casting method, an injection method, or a stretching method.

The aromatic polyimide film having high heat resistance is preferably one obtained from the viewpoints of the polyimide film obtained, heat resistance, mechanical strength, and the like: an aromatic polyimide obtained by polymerizing and imidizing 30 mol% or more, particularly 50 mol% or more of a biphenyltetracarboxylic acid component (particularly 3,3', 4' -biphenyltetracarboxylic dianhydride) and 50 mol% or more of a phenylenediamine component (particularly p-phenylenediamine).

Specific examples of the commercial products include Ube Industries, trade names "UPILEX S", kanegafuchi Chemical Industry Co., ltd., trade names "ApicalAH", "ApicalNPI", DU PONT-TORAY CO., and trade names "CAPTON H type", LTD.

On the other hand, thermoplastic aromatic polyimide is a polymer having an imide structure in its main chain, and has a glass transition temperature of approximately 150 to 350 ℃, preferably 200 to 300 ℃, and an elastic modulus drastically decreases in a temperature range equal to or higher than the glass transition temperature.

For the thermoplastic aromatic polyimide, as aromatic tetracarboxylic acid component can also be used benzophenone tetracarboxylic acid dianhydride, benzene four formic acid dianhydride, but preferably 3,3',4' -biphenyl four carboxylic acid dianhydride, 2, 3',4' -biphenyl four carboxylic acid dianhydride. Among them, in particular, as the aromatic tetracarboxylic acid component, it is preferable to use 2, 3',4' -biphenyltetracarboxylic dianhydride in an amount of 30 mol% or more, particularly 50 mol% or more. Further, as the aromatic diamine component, diaminodiphenyl ethers, bis (aminophenoxy) benzenes, bis (aminophenoxy phenyl) sulfones, and bis (aminophenoxy phenyl) propanes are preferable. Further, as the diamine component, a diamine obtained by using 5 to 25 mol% of diaminosiloxane and 75 to 95 mol% of aromatic diamine can be suitably used.

The thickness of the resin film is not particularly limited. Usually 5 μm to 150. Mu.m, preferably 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 75 μm or less.

The surface of the resin film may be subjected to plasma treatment, or the surface may be treated with an aminosilane coupling agent at the stage of the polyamic acid film, or further subjected to drying and heating treatment.

< haze of film >

In the present film laminate, the film haze is preferably 15% or less, more preferably 13% or less, and still more preferably 12% or less, for the purpose of coping with optical applications.

< hue >

The present film laminate has a color (b) from the viewpoint of preventing color change due to the deterioration of the constituent members with time ^* The value) is preferably 70 or more, more preferably 75 or more, 80 or more, particularly 85 or more. The upper limit is preferably about 98.

In order to color tone (b) of the film laminate ^* The value) is set in the above range, for example, a yellow dye may be compounded in a large amount, set inFor basic color tone, dyes or pigments of other colors are suitably combined, and the like. However, the method is not limited thereto.

< light transmittance >

The film laminate preferably has a light transmittance of 1% or less at a wavelength of 450nm and a light transmittance of 15% to 30% at a wavelength of 550 nm.

As described above, the emission spectrum of the LED light source generally has a spectrum having a strong emission intensity in the vicinity of 450nm, and has a characteristic that the emission intensity in the vicinity of 550nm is significantly lower than the emission intensity in the spectrum in the vicinity of 450 nm. Therefore, when the film laminate has the light transmittance in the above wavelength region, the light emission intensity of the light emitted from the LED light source can be made uniform because the wavelength region in which the light emission intensity of the light emitted from the LED light source is insufficient can be enhanced without blocking the light emission performance (light transmittance) of the light emitted from the LED light source when the film laminate is incorporated into an image display device in combination with the LED light source.

From the above-mentioned viewpoints, the light transmittance at a wavelength of 450nm in the present film laminate is preferably 1% or less, more preferably 0.5% or less, particularly 0.1% or less, and particularly 0.05% or less.

On the other hand, the light transmittance at a wavelength of 550nm is preferably 15% to 30%, more preferably 20% or more and 30% or less, and 25% or more and 30% or less.

Further, from the viewpoint of color uniformity of the display screen, it is preferable that the transmittance is larger as the wavelength is higher at least in a region from the short wavelength (400 nm) side to the long wavelength (720 nm) side of the visible light region. More specifically, it is preferable that: the transmittance at each measurement wavelength of (1) 400nm, (2) 550nm, (3) 650nm, and (4) 720nm increases as the wavelength is higher.

Further, it is preferable that any 1 or more of the following conditions (5) to (8) is satisfied, more preferably any 2 or more of the conditions (5) to (8) is satisfied, still more preferably any 3 or more of the conditions (5) to (8) is satisfied, and particularly preferably all of the conditions (5) to (8) are satisfied.

(5) From the viewpoint of color uniformity of the display screen, the maximum value of the light transmittance in the measurement wavelength range of 400nm to 480nm is preferably 1% or less, more preferably 0.5% or less and 0.1% or less.

(6) From the viewpoint of color uniformity of the display screen, the maximum value of the light transmittance in the measurement wavelength range of 500nm to 600nm is preferably 30 to 60%, more preferably 40% or more and 60% or less, and further preferably 50% or more and 60% or less.

(7) The maximum value of the light transmittance in the measurement wavelength range of 610nm to 680nm is preferably 30 to 60%, more preferably 35% or less than 60%, and further preferably 40% or more than 60% or less from the viewpoint of color uniformity of the display screen.

(8) From the viewpoint of color uniformity of the display screen, the maximum value of the light transmittance in the measurement wavelength range of 700nm to 720nm is preferably 50 to 70%, more preferably 55% or more and 70% or less, and further preferably 60% or more and 70% or less.

In the present film laminate, as described above, in order to control the light transmittance in each specific wavelength region, for example, the type and amount of the dye and/or pigment contained in the present optical film are preferably controlled by adjusting the type and amount. It is particularly preferable that at least 2 or more dyes selected from yellow dyes, red dyes, blue dyes, and brown dyes, 3 or more of them, and 4 or more of them are appropriately selected and contained in the present optical film.

< method for producing the thin film laminate >

The film laminate can be produced by a method of forming the adhesive layer on the resin film and adhering the optical film.

< present display unit >

The display unit (referred to as "the present display unit") can be configured using the present optical film or the present film laminate.

As an example of the display unit, as shown in fig. 2 or 3, there may be mentioned: an example is where the optical film or the film laminate is disposed on the lower side of the LED light source, that is, on the opposite side from the viewing side, and the reflective material (metal layer) is disposed on the lower side of the optical film or the film laminate, that is, on the opposite side from the viewing side, with the position of the LED light source as a reference. By disposing the reflective material, even when light emitted from the LED light source is unintentionally leaked to the back side (lower side) in the case where the light is emitted only to the upper side (visible side), the light can be effectively utilized. Furthermore, it is preferable that the light emitted from the LED light source is designed to propagate at least in two directions, i.e., in the upper and lower sides, i.e., in the visible side and the opposite side.

In the present display unit having the above-described configuration, as shown in fig. 2 or 3, the light L1 emitted from the LED light source is transmitted to the upper visual side among the light beams emitted from the LED light source, and the light L1 transmitted to the lower side, i.e., the opposite side to the visual side among the light beams emitted from the LED light source is reflected by the reflective material after being absorbed by the light L2 having a predetermined wavelength by the present optical film or the present film laminate, and is supplied to the visual side of the LED light source as the light L2 having the predetermined wavelength absorbed by the present optical film or the present film laminate. Therefore, according to the present display unit, the light L1 and the light L2 can be supplied to the visible side.

The maximum value of the emission spectrum of the LED light source in the wavelength range of 400nm to 480nm is usually larger than the maximum value of the emission spectrum in the wavelength range of 500nm to 600nm, for example, usually 1.5 to 2 times larger.

Since the optical film or the film laminate selectively absorbs light in the wavelength range of 400nm to 480nm and does not selectively absorb light in the wavelength range of 500nm to 600nm, the difference between the maximum value of the light emission spectrum in the wavelength range of 400nm to 480nm and the maximum value of the light emission spectrum in the wavelength range of 500nm to 600nm can be reduced with respect to the light L1 and the light L2 supplied from the display unit to the visible side, and the uniformity of the light emission spectrum can be realized and the luminance can be improved by adding the light L1 and the light L2.

Therefore, in the present display unit, it is not necessary to enhance unnecessary light emission intensity at a wavelength having sufficient light emission intensity, and therefore at a wavelength of 550nm, the light transmittance (T1 _<550> >) Relative radiation intensity (T2) to the LED light source _<550> ) Is a sum of (T)1 _<550> +T2 _<550> ) Is set to 80% or more, 90% or more, or 95% or more.

Further, the content may be 75% or less, 70% or less, or 65% or less. From the viewpoint of maintaining the balance with the light on the long wavelength side without excessively intense 550nm light, it is preferably 75% or less.

On the other hand, the transmittance (T1 _<450> ) Relative radiation intensity (T2) to the LED light source _<450> ) Is a sum of (T1) _<450> +T2 _<450> ) The content is set to 105% or less, 103% or less, or 101% or less.

Incidentally, the relative radiation intensity (T2) of the LED light source at a wavelength of 550nm _<550> ) Typically 30-50%, the relative radiation intensity (T2) of the LED light source at a wavelength of 450nm _<450> ) Typically 80 to 100%.

The LED sources may be of a straight-down type in which light sources are arranged in parallel planes. In this case, a diffusion plate or the like may be provided as necessary between the present optical film or the present film laminate and the LED light source.

The planar light source may be an edge illumination system including an LED light source disposed on an edge side and a light guide plate that guides primary light emitted from the LED light source to a visible side and emits the primary light.

The display unit may optionally include a known optical member. For example, a known diffusion plate, diffusion sheet, prism sheet, light guide plate, or the like may be provided.

(display device of the present display)

The present display unit described above may be combined with a display such as a liquid crystal unit to form a display device (referred to as "present display device") such as a liquid crystal display device.

In this case, the liquid crystal cell is generally configured by sandwiching the liquid crystal cell between 2 polarizing plates.

In addition, a coated type polarizing plate (circular polarizing plate) may be used.

The display device of the present invention may further optionally include a transparent electrode layer (e.g., a thin film sensor), an optical compensation member for performing optical compensation, a color filter substrate, a thin film transistor substrate, a lens film, a diffusion sheet, a hard coat layer, an antireflection layer, a low reflection layer, an antiglare layer, a front scattering layer, a primer layer, an antistatic layer, an undercoat layer, an adhesive layer, and the like, as necessary.

As described above, on the premise that the present optical film or the present film laminate is mounted as a constituent member of a display from the beginning, with the time degradation of the constituent member, for example, the time degradation of the transparent electrode as described above, the color change of the display screen due to the discoloration is predicted and the types and amounts of dyes and pigments are adjusted, and the color tone of the present optical film or the present film laminate is adjusted in advance to the same level as the color tone after the change, so that the color tone after the change of the degraded member can be the same color tone, and as a result, the color change of the display screen can be made inconspicuous. For example, it is predicted that the transparent electrode (ITO member) changes its color to yellow or tea color with time degradation, and the optical film or the film laminate may be colored to brown with a tea color dye. In this way, even when the transparent electrode (ITO member) is discolored to yellow or tea color with time degradation, it is possible to prevent the color from being unexpected in advance, which is different from the color that the display screen should have.

Description of the term >

In the present invention, the case called "film" also includes the case of "sheet", and the case called "sheet" also includes the case of "film".

In addition, the case expressed as "panel" as in the case of an image display panel, a protective panel, and the like includes a plate body, a sheet, and a film.

In the present invention, the term "X to Y" (X, Y is an arbitrary number) means X or more and Y or less unless otherwise specified, and also includes the term "preferably greater than X" or "preferably less than Y".

The term "X" or "X" is an arbitrary number, and unless otherwise specified, the term "preferably greater than X" is included, and the term "Y" or "Y" is an arbitrary number, and unless otherwise specified, the term "preferably less than Y" is included.

Examples

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples.

< Material >

The various materials used in examples and comparative examples were prepared as follows.

(dark brown dye)

As the brown dye, 2, 3-bis [ [ (2-hydroxyphenyl) methylene ] amino-N ] -2-butenedinitrile (2-) ] nickel having a structure represented by the following formula (formula 1) was prepared.

(blue dye)

As a blue dye, 4, 11-diamino-2- (3-methoxypropyl) -1H-naphthalene [2,3-f ] isoindole-1, 3,5,10 (2H) -tetraone having a structure represented by the following formula (2) was prepared.

(Red dye)

As the red dye, 3-methyl-6- [ (4-methylphenyl) amino ] -3H-dibenzo [ f, ij ] isoquinoline-2, 7-dione having a structure represented by the following formula (formula 3) was prepared.

(yellow dye)

As the yellow dye, 1' - [ (6-phenyl-1, 3, 5-triazine-2, 4-diyl) bis (imino) ] bis (9, 10-anthracenedione) having a structure represented by the following formula (formula 4) was prepared.

< method for producing polyester A >

100 parts by mass of dimethyl terephthalate and 60 parts by mass of ethylene glycol were used as starting materials, 0.09 parts by mass of magnesium acetate/tetrahydrate as a catalyst was fed into a reactor, the reaction initiation temperature was 150 ℃, methanol was distilled off and the reaction temperature was gradually increased, and after 3 hours, it was set to 230 ℃. After 4 hours, the transesterification reaction was substantially ended. After 0.04 parts by mass of acid ethyl phosphate was added to the reaction mixture, 0.04 parts by mass of antimony trioxide was added thereto, and polycondensation reaction was performed for 4 hours. That is, the temperature was slowly raised from 230 ℃ to 280 ℃. On the other hand, the pressure gradually decreased from the normal pressure to 0.3mmHg. After the reaction was started, the reaction was stopped at a point of time corresponding to an intrinsic viscosity of 0.63dl/g by a change in stirring power of the reaction vessel, and the polymer was discharged under nitrogen pressure. The intrinsic viscosity of the obtained polyester A was 0.65dl/g.

< method for producing polyester B >

In the polyester A manufacturing method, adding acid ethyl phosphate 0.04 parts by mass, adding dispersed in ethylene glycol average particle diameter 1.6μm silica particles 0.3mass, antimony trioxide 0.04 parts by mass, corresponding to an intrinsic viscosity of 0.65dl/g time point stop polycondensation reaction, using the same method as polyester A manufacturing method to obtain polyester B. The intrinsic viscosity of the obtained polyester B was 0.65dl/g.

< method for producing polyester C >

After the pre-crystallization of the polyester A at 160℃in advance, solid-phase polymerization was carried out in a nitrogen atmosphere at 220℃to obtain a polyester C having an intrinsic viscosity of 0.85 dl/g.

< method for producing polyester D >

Polyester a was fed to a twin-screw extruder with a vent, and the yellow dye was mixed therein, melt-kneaded and flaked to produce polyester D as a dye master batch having an intrinsic viscosity of 0.65dl/g and a dye concentration of 9 mass%.

< method for producing polyester E >

The polyester A was fed to a twin screw extruder with vent holes, and each dye was mixed so as to have a concentration of 0.5 mass% of the red dye, 2.5 mass% of the blue dye and 2 mass% of the brown dye, and melt kneaded and flaked to produce a polyester E as a dye master batch having an intrinsic viscosity of 0.65dl/g and a dye concentration of 5 mass%.

Examples 1 to 1

< method for producing polyester film F1 >

The polyester a and the polyester B were mixed at a compounding ratio of polyester a/b=90/10 (mass%) to prepare a layer raw material, and the polyester A, D and the polyester E were mixed at a compounding ratio of polyester a/D/e=82.4/16/1.6 (mass%), and the B layer raw material was fed to 2 twin screw extruders, respectively, and melted at 285 ℃, and then, the layer a was used as the outermost layer (outer layer) and the layer B was used as the intermediate layer, and the 2 and 3 layers were co-extruded onto a casting drum cooled to 20 ℃ to obtain a non-oriented sheet by cooling and solidification. Next, after stretching 3.0 times in the machine direction at 90℃the following functional layer compositions x, y were applied in an amount of 0.04g/m (after drying) ² After a preheating step in a tenter oven and a transverse stretching step of 4.3 times at 125 ℃, a heat treatment was performed at 230 ℃ for 5 seconds, and a relaxation of 4.0% was applied in the width direction at 140 ℃ to obtain a polyester film (sample) F1 having a layer structure of functional layer X/a layer/B layer/a layer/functional layer y=0.04 μm/5 μm/40 μm/5 μm/0.04 μm and a thickness of 50 μm.

The polyester film (sample) had a dye pigment concentration of 1.216 mass% and a yellow/red/blue/brown dye mass ratio of 1.152/0.006/0.032/0.026.

[ functional layer composition x, y ]

(P) crosslinking agent

(P1): hexamethoxy methylolmelamine

(P2): acrylic polymers having oxazolinyl groups and polyalkylene oxide chains

(oxazolinyl amount=4.5 mmol/g, nippon Shokubai co., ltd.)

(P3): polyglycidyl ethers of polyglycerol

(Q) Binder resin

(Q1): polyvinyl alcohol having a degree of saponification of 88% and a degree of polymerization of 500

(Q2) polyester resin: an aqueous dispersion of a polyester resin copolymerized with the following composition

Monomer composition: (acid component) terephthalic acid/isophthalic acid-5-sodium sulfonate// (glycol component) ethylene glycol/1, 4-butanediol/diethylene glycol=56/40/4// 70/20/10 (mol%)

(R) antistatic agent

Copolymerizing diallyl dimethyl ammonium chloride with N-methylolacrylamide and N-dimethylacrylamide at a ratio of 90/5/5 by mass, with a number average molecular weight of 20000, and a cationic group-containing resin having a cation in the main chain

(S) particles

Silica particles (average particle size: 70 nm)

The functional layer composition X for forming the functional layer X as an easy-to-adhere layer was prepared by compounding the above-mentioned P1, P2, Q2 and S (particles) at a ratio of P1/P2/Q2/s=20/20/55/5 (mass%).

On the other hand, the functional layer composition Y for forming the functional layer Y as an antistatic layer was prepared by compounding the above-described P2, P3, Q1, R (antistatic agent) and S (particles) in a ratio of P2/P3/Q1/R/s= 15/15/25/40/5 (mass%).

Examples 1 to 2

< method for producing polyester film F2 >

A polyester film (sample) F2 having a layer structure of functional layer X/a layer/B layer/a layer/y=0.04 μm/12.5 μm/100 μm/12.5 μm/0.04 μm and a thickness of 125 μm was obtained in the same manner as the polyester film F1 except that the polyester a/b=90/10 (mass%) was mixed to prepare a layer raw material and the polyester a/B was mixed to prepare a layer raw material B with the polyester a/D/e=93/5/2 (mass%) and the polyester A, D and E were mixed to prepare a layer raw material.

The dye pigment concentration in the polyester film (sample) was 0.44 mass%, and the dye mass ratio of yellow/red/blue/brown was 0.36/0.008/0.04/0.032.

Examples 1 to 3

< method for producing polyester film F3 >

A polyester film (sample) F3 having a layer structure of functional layer X/a layer/B layer/a layer/y=0.04 μm/15 μm/120 μm/15 μm/0.04 μm and a thickness of 150 μm was obtained in the same manner as in the polyester film F1 except that the polyester a/b=90/10 (mass%) was mixed to prepare a layer raw material, and the polyester a/D/e=94/5/1 (mass%) was mixed to prepare a layer raw material.

The polyester film (sample) had a dye pigment concentration of 0.40% by mass and a dye mass ratio of yellow/red/blue/brown of 0.36/0.004/0.02/0.016.

Examples 1 to 4

< method for producing polyester film F4 >

A polyester film (sample) F4 having a layer structure of 0.04 μm/18 μm/144 μm/18 μm/0.04 μm and a thickness of 180 μm was obtained in the same manner as the polyester film F1 except that the polyester a/b=90/10 (mass%) was mixed to prepare a layer a raw material, and the polyester A, D and E were mixed to prepare a layer B raw material at a polyester a/D/e=94.5/5/0.5 (mass%) to prepare a layer B raw material.

The dye pigment concentration in the polyester film (sample) was 0.38 mass%, and the dye mass ratio of yellow/red/blue/brown was 0.36/0.002/0.01/0.008.

Examples 1 to 5

< method for producing polyester film F5 >

A polyester film (sample) F5 having a layer structure of functional layer X/a layer/B layer/a layer/y=0.04 μm/12.5 μm/100 μm/12.5 μm/0.04 μm and a thickness of 125 μm was obtained in the same manner as the polyester film F1 except that the polyester a/b=90/10 (mass%) was mixed to prepare a layer raw material and the polyester a and B was mixed to prepare a layer raw material and the polyester a/D/e=89/10/1 (mass%) was mixed to prepare a layer raw material.

The polyester film (sample) had a dye pigment concentration of 0.76 mass% and a dye mass ratio of yellow/red/blue/brown of 0.72/0.004/0.02/0.016.

Examples 1 to 6

< method for producing polyester film F6 >

In example 1-1, a polyester film (sample) F6 having a layer structure of 0.04 μm/5 μm/40 μm/5 μm and a thickness of 50 μm was obtained in the same manner as in example 1-1 except that only the functional layer X was provided instead of providing the functional layer X, Y.

Examples 1 to 7

< method for producing polyester film F7 >

In example 1-1, a polyester film (sample) F7 having a layer structure of a layer/B layer/a layer/functional layer y=5 μm/40 μm/5 μm/0.04 μm and a thickness of 50 μm was obtained in the same manner as in example 1-1 except that only the functional layer Y was provided instead of providing the functional layer X, Y.

Examples 1 to 8

< method for producing polyester film F8 >

A polyester film (sample) F8 having a layer structure of a layer/B layer/a layer=5 μm/40 μm/5 μm and a thickness of 50 μm was produced in the same manner as in example 1-1 except that the compounding ratio of the raw material of the layer a was changed to the compounding ratio of polyester a/c=90/10 (mass%) and that no functional layer X, Y was provided in example 1-1.

Comparative examples 1 to 1

< method for producing polyester film F9 >

A polyester film (sample) F9 having a layer structure of 0.04 μm/12.5 μm/100 μm/12.5 μm/0.04 μm and a thickness of 125 μm was obtained in the same manner as in example 1-1 except that the above-mentioned polyesters A and D were mixed at a compounding ratio of polyester A/D=95/5 (mass%) in the preparation of the B layer raw material of example 1-1.

The dye pigment concentration in the polyester film (sample) was 0.36 mass%, and the dye mass ratio of yellow/red/blue/brown was 0.36/0/0/0.

Examples 2 to 1

< production of film laminate G1 >

In a polyimide film (b) for electrical insulation having a thickness of 50. Mu.m ^* Value: 96 After a coating liquid composed of the following composition for forming an adhesive layer was applied thereto, a heat treatment was performed at 100℃for 5 minutes using a hot air circulation oven to obtain an adhesive layer having a coating amount (after drying) of 25. Mu.m.

Next, the polyester film (sample) F1 was superimposed on the adhesive layer so that the functional layer X side was in contact with the adhesive layer, and a film laminate G1 (sample) was obtained.

< composition for Forming adhesive layer >

An adhesive layer-forming composition was prepared by mixing 20g of 4-phenylbenzophenone as a photopolymerization initiator with 1kg of an acrylate copolymer (mw= 540000 mn=67000 Mw/mn=8 theoretical Tg-50 ℃) obtained by randomly copolymerizing 75 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of vinyl acetate, and 5 parts by mass of acrylic acid.

Examples 2 to 2

A film laminate G2 (sample) was produced in the same manner as in example 2-1 except that the polyester film (sample) F1 was changed to the polyester film (sample) F2.

Examples 2 to 3

A film laminate G3 (sample) was produced in the same manner as in example 2-1 except that the polyester film (sample) F1 was changed to the polyester film (sample) F3.

Examples 2 to 4

A film laminate G4 (sample) was produced in the same manner as in example 2-1 except that the polyester film (sample) F1 was changed to the polyester film (sample) F4.

Examples 2 to 5

A film laminate G5 (sample) was produced in the same manner as in example 2-1 except that the polyester film (sample) F1 was changed to the polyester film (sample) F5.

Examples 2 to 6

A film laminate G6 (sample) was produced in the same manner as in example 2-1 except that the polyester film (sample) F1 was changed to the polyester film (sample) F6.

Examples 2 to 7

A film laminate G7 (sample) was produced in the same manner as in example 2-1 except that the polyester film (sample) F1 was changed to the polyester film (sample) F7.

Examples 2 to 8

A film laminate G8 (sample) was produced in the same manner as in example 2-1 except that the polyester film (sample) F1 was changed to the polyester film (sample) F8.

Comparative examples 2 to 1

A film laminate G9 (sample) was produced in the same manner as in example 2-1 except that the polyester film (sample) F1 was changed to the polyester film (sample) F9.

< evaluation method >

The method for measuring various values performed in examples and comparative examples will be described.

(1) Intrinsic viscosity (dl/g) of polyester

1g of polyester was precisely weighed, 100ml of a mixed solvent of phenol/tetrachloroethane=50/50 (mass ratio) was added to dissolve the polyester, and the intrinsic viscosity was measured at 30 ℃.

(2) Average particle diameter (d) of particles in polyester raw material ₅₀ ：μm)

The cumulative (weight basis) 50% value in the equivalent spherical distribution was measured as the average particle diameter using a centrifugal sedimentation particle size distribution measuring apparatus (model SA-CP3, shimadzu corporation).

(3) Method for measuring film thickness of functional layer (X) (Y)

The polyester films (samples) produced in examples 1-1 to 1-8 and comparative example 1-1 and the film laminates (samples) produced in examples 2-1 to 2-8 and comparative example 2-1 were each produced using RuO ₄ The surface of the functional layer (X) (Y) is dyed and embedded in epoxy resin. Then, ruO is performed again on the slice manufactured by the ultra-thin slice method ₄ The functional layer was stained and the cross section was measured by a transmission electron microscope (H-7650, acceleration voltage 100kV, hitachi Co.).

(4) Film haze, total light transmittance

The polyester films (samples) produced in examples 1-1 to 1-8 and comparative example 1-1 and the film laminates (samples) produced in examples 2-1 to 2-8 and comparative example 2-1 were each measured for haze and total light transmittance according to JIS K7136 using a haze meter DH-2000 manufactured by Nippon Denshoku industries Co., ltd.

(5) Evaluation of color tone of optical film and film laminate (b ^* )

The polyester films (samples) produced in examples 1-1 to 1-8 and comparative example 1-1 and the film laminate (samples) produced in examples 2-1 to 2-8 and comparative example 2-1 were each measured by the color tone reflection method b using a spectrocolorimeter "CM-3700d" (manufactured by KONICA MINOLTA, INC.) ^* Values. In the measurement, the light source C was used.

(6) Method for evaluating adhesion (evaluation for practical property substitution)

For the polyester films (samples) produced in examples 1-1 to 1-8 and comparative example 1-1 and the film laminate (samples) produced in examples 2-1 to 2-8 and comparative example 2-1, a mixed coating solution of 74 parts by mass of KAYANOVA FOP-1100 (manufactured by Nippon Kagaku Co., ltd.) and 86 parts by mass of methyl ethyl ketone as an ultraviolet-curable acrylic resin was applied to the functional layer (X) formation surface of the polyester film (sample) so that the dry film thickness was 2. Mu.m, and the film laminate was at 70 DEG C Drying for 1 min to remove solvent, and irradiating with 60mJ/cm ² Ultraviolet light cures it to form a hard coat layer.

The resulting hard-coated film was cut into a size of 10mm×10mm, and an 18mm wide tape (nichiba co., ltd. Manufactured by tape (registered trademark) CT-18) was attached thereto, and the peeled surface after rapid peeling at a peeling angle of 180 degrees was observed and evaluated according to the following criteria.

Decision criterion

(very good): the area of peeling between the functional layer (X) and the hard coat layer was less than 20%.

● (good): the area of peeling between the functional layer (X) and the hard coat layer is 20% or more and less than 50%.

Delta (bad): the area of separation between the functional layer (X) and the hard coat layer is 50% or more.

(7) Antistatic evaluation method

For the polyester films (samples) produced in examples 1-1 to 1-8 and comparative example 1-1, and the film laminates (samples) produced in examples 2-1 to 2-8 and comparative example 2-1, resistance measuring devices were used, respectively: HP4339B and measurement electrode: HP16008B, after humidity-conditioning the polyester film (sample) or film laminate (sample) for 30 minutes at 23 ℃ under a measurement atmosphere of 50% rh, measured the surface resistance value.

Decision criterion

O (good): 1X 10 ¹¹ Omega or less.

Delta (bad): over 1X 10 ¹¹ Ω。

(8) Evaluation of brightness (uniformity) and color (uniformity) of display screen (evaluation for practical characteristics substitution)

The polyester films (samples) produced in examples 1-1 to 1-8 and comparative example 1-1 were measured for light transmittance (T1) at each measurement wavelength in the wavelength region of 400nm to 720nm using a KONICA MINOLTA, INC. Spectrometry colorimeter "CM-3700 d".

On the other hand, the relative radiation intensity (T2) at each measurement wavelength of 400nm to 720nm was measured using an LED surface light source for evaluation (TREVIEWER A-500 manufactured by TRYTEC Co., ltd.). Further, the total value (T1+T2) of T1 and T2 at 450nm and 550nm was obtained.

Next, an aluminum reflecting plate was attached to one side of the two-sided light emitting LED surface light source, and the samples of examples and comparative examples were sandwiched between the surface light source and the aluminum reflecting plate, and the side surfaces were masked with a light shielding tape. Then, visual observation was performed on the surface of the LED light source on the side where the aluminum reflecting plate was not attached, and the brightness of the light source and the color tone of the light source were evaluated in a sensory manner. Based on the result of the total value of T1 and T2 and the result of the sensory evaluation, the judgment is made according to the following criteria.

Decision criterion

O (good): 450nm: t1 _<450> +T2 _<450> The total value of (2) is 105% or less.

550nm：T1 _<550> +T2 _<550> The total value of (2) is 80% or more.

(the display screen looks uniform and white and vivid.)

X (difference): 450nm: t1 _<450> +T2 _<450> The total value of (2) exceeds 105%.

(the display screen appears to be a screen with a strong color tone of blue locally.)

Or alternatively, the process may be performed,

550nm：T1 _<550> +T2 _<550> the total value of (2) is less than 80%.

(the brightness of the display screen does not change greatly from before the aluminum reflective plate is mounted.)

On the other hand, the film laminates (samples) produced in examples 2-1 to 2-8 and comparative example 2-1 were measured for light transmittance (T1) and relative radiation intensity (T2) in the same manner as in the polyester film (sample), and the total value (T1+T2) of T1 and T2 at 450nm and 550nm was obtained.

Next, similar to the polyester film (sample), the brightness of the light source and the color tone of the light source were evaluated in a sensory manner, and the color (uniformity) of the display screen was determined based on the result of the total value of T1 and T2 and the result of the sensory evaluation.

Decision criterion

O (good): 450nm: t1 _<450> +T2 _<450> The total value of (2) is 105% or less.

550nm：T1 _<550> +T2 _<550> The total value of (2) is 75% or less.

(color of display screen looks uniform.)

Or alternatively, the process may be performed,

550nm：T1 _<550> +T2 _<550> the total value of (2) exceeds 75%.

(color of display screen looks locally nonuniform.)

(9) Tone recognizability (evaluation for practical property substitution)

As an evaluation for color tone substitution of the deteriorated transparent electrode layer, the following test was performed.

Using an inkjet printer, a coating liquid composed of a dye colored in a tea color system was used as an ink for the printer, and lattice-like pattern printing was performed on an A4-size transparent polyethylene terephthalate (PET) film substrate (100 μm).

Next, the polyester films (samples) produced in examples 1-1 to 1-8 and comparative example 1-1, or the film laminates (samples) produced in examples 2-1 to 2-8 and comparative example 2-1 were arranged on the transparent film with the lattice-like pattern printed layer so that the resin film side was the visible side. The visibility of the pattern printed layer when viewed from the polyester film (sample) or film laminate (sample) side was determined based on the following determination criteria.

Decision criterion

O (good): the same hue as the film color was difficult to observe the pattern printed layer.

Delta (general): although the color of the film was the same as that of the film, the outline of the pattern printed layer was slightly observed.

X (difference): the pattern printed layer can be clearly confirmed.

The optical characteristics of the reference sample (evaluation for replacement of the deteriorated transparent electrode layer) used in the evaluation are as follows.

L ^* Value: 64.9a ^* Value: 13.5b ^* Value: 96.7

(10) Comprehensive evaluation

Based on the above evaluation, that is, the judgment results in each item of brightness, color tone recognition, adhesiveness, and antistatic property of the display screen, the polyester films (samples) produced in examples 1-1 to 1-8 and comparative example 1-1 were comprehensively evaluated based on the following criteria.

O (good): all items of brightness, tone recognition, adhesion, and antistatic property of the display screen were judged as o.

Delta (bad): the brightness and the tone recognition property of the display screen are good, but at least 1 of the adhesion property and the antistatic property is delta judgment.

X (difference): at least one of the brightness and the tone recognition of the display screen is an x determination.

On the other hand, the film laminates (samples) produced in examples 2-1 to 2-8 and comparative example 2-1 were comprehensively evaluated based on the above-described evaluation, that is, the determination results in each item of color (uniformity), color tone recognition, adhesiveness, and antistatic property of the display screen, based on the following criteria.

(determination criterion)

Delta (bad): the brightness and tone recognition property of the display screen are good, but at least 1 of the adhesion property and antistatic property is good

< evaluation results >

Table 1 below shows the characteristics of each of the polyester films produced in examples 1-1 to 1-8 and comparative example 1-1, and table 2 below shows the characteristics of each of the film laminates produced in examples 2-1 to 2-8 and comparative example 2-1.

TABLE 1

TABLE 2

< investigation >

From comparative examples 1-1, 2-1 or reference example (FIG. 4), it was confirmed that a general film and film laminate for optical use have a tendency to have a high design transmittance as a whole regardless of the measurement wavelength. Further, it was confirmed that the selective light control function could not be provided by simply coloring the film. For example, it was confirmed by spectroscopic spectroscopy that the transmittance at each measurement wavelength was almost constant. Further, it is also known that when the light emission intensity of light having a wavelength of 450nm is not required to be strong, the color of the obtained display screen is a blue color, and it is difficult to obtain a display screen having a uniform white color.

On the other hand, it is known that by using the optical film (referred to as "the present optical film") or the film laminate (referred to as "the present film laminate") obtained in the examples, the light transmittance in a specific wavelength region can be selectively controlled.

Based on the above examples and the results of experiments conducted by the inventors, it is known that: by arbitrarily controlling the transmittance in a specific wavelength region in the optical film or film laminate, light in a wavelength region that is not intended to be transmitted can be blocked.

Specifically, the use of dyes and/or pigments enables control of film haze, hue (b) of polyester films ^* ) The value, the transmittance of each wavelength can be controlled, the haze of the film can be adjusted to be less than 6%, and the transmittance of 450nm can be adjusted4% or less, a light transmittance of 550nm of 20% or more, and a color tone (b) ^* ) The value was adjusted to 50 or more to prepare the present optical film.

In addition, specifically, the present film laminate can be prepared as follows: a film laminate comprising a resin film laminated on one surface of an optical film comprising a polyester film containing a dye and/or a pigment via an adhesive layer, wherein the film haze of the film laminate is adjusted to 15% or less, the light transmittance at 450nm is adjusted to 1% or less, the light transmittance at 550nm is adjusted to 15% to 30%, and the color tone (b) ^* ) The value is adjusted to 70 or more.

The light emitted from the LED light source has a variation in transmittance at each wavelength, and particularly tends to be weak in emission intensity in a wavelength region (500 nm to 600 nm) that is perceived as noticeable (fig. 1). However, the aim is to: when an LED light source having a peak of an emission spectrum in the same wavelength region is mounted on a display together with the optical film or the film laminate, the entire light source is uniformized without blocking light emitted from the LED light source and enhancing a wavelength region where emission intensity is insufficient. As a result, it was found that: since the variation in light transmittance of each wavelength of the LED light source is eliminated to be uniform, the uniformity of the color of the display screen and the further improvement of the brightness can be achieved.

As shown in fig. 2 and 3, the present optical film or the present film laminate is disposed between the LED light source and the reflective material (metal layer), and light emitted from the LED light source propagates in the up-down 2 directions, that is, in the 2 directions of the present optical film or the present film laminate side and the visible side, so that the effect of the present invention can be further enjoyed in the display unit having the above-described configuration.

The light emitted from the LED light source has 2 directions of light L1 (top) toward the visible side and light L1 (bottom) toward the lower side. After passing through the optical film or the film laminate, the light L1 (bottom) becomes light L2 having a wavelength distribution such that the transmittance at a wavelength of 400nm to 720nm gradually increases toward the higher wavelength side. The light L2 is reflected by the reflective material (metal layer), and then is directed back toward the visible side while changing its direction. Then, the light L1 (top) is merged and directed to the display screen. As a result, the light quantity (light L1 (top) +light L2) on the visible side of the LED light source is increased as a whole, and by further homogenizing, the color of the display screen can be homogenized and the luminance can be further improved. For example, even when a (digital) image is read using light having a wavelength of around 550nm, the (digital) image is not blurred, and a clearer (digital) image can be read.

Further, in the case where the optical film or the film laminate itself is colored in a tea color system or the like, it is possible to prevent the color of the display component member from being unexpectedly different from the color that the display screen should have, for example, due to the coloring (phenomenon of changing to a yellow color system, a tea color system or the like) associated with the aging degradation of the transparent electrode (ITO member) in advance. That is, on the premise that the present optical film or the present film laminate is mounted as a constituent member of the display from the beginning, color change of the display screen due to deterioration (for example, transparent electrode) and discoloration of the constituent member with time is predicted in the future, and the present optical film or the present film laminate is adjusted to the same color tone in advance, so that the color tone after the change of the deteriorated member is the same color tone, and as a result, the color change of the display screen can be made inconspicuous.

As described above, according to the results of the studies by the present inventors, the present optical film or the present film laminate, which is designed based on a new idea of fully utilizing the light emission performance inherent in the LED light source and based on the "enhancement" of the light emission intensity of the light source, can selectively control the minute light transmittance and adjust the color tone.

In addition, the present invention is applied to a structural member for a display (display screen) focusing on the obtained heterogeneous operational effects.

Industrial applicability

According to the optical film of the present invention and the film laminate of the present invention, the light transmittance in a specific wavelength region is arbitrarily controlled, and so-called light control is good. In particular in the case of use in combination with LED light sources, the aim is to: the light emission performance (transmittance) of the light emitted from the LED light source is not hindered, but the wavelength region with insufficient emission intensity is selectively enhanced from the short wavelength (400 nm) side to the long wavelength (720 nm) side of the visible light region, so that the entire light is uniformized. As a result, the light transmittance of the light emitted from the LED light source varies at each wavelength, and this is considered to be a cause of variation in the color of the display screen (for example, when the light emission intensity of 450nm is too high, blue tends to be intense in the color of the obtained display screen), and the use of the present optical film or the present film laminate in combination eliminates the variation and makes it possible to uniformize the color of the display screen and further improve the brightness. For example, even when a (digital) image is read by light having a wavelength in the visible light range around 550nm, the (digital) image is not blurred, and a clear (digital) image can be read.

Further, the coloring of the film or the film laminate itself can suppress unexpected color changes in the display screen that occur with the deterioration of the constituent members such as the transparent electrode layer over time. Further, when the functional layer is provided in a film or a film laminate, adhesiveness and antistatic properties can be imparted to the functional layer such as a hard coat layer, and thus the industrial value thereof is high.

Claims

1. An optical film comprising a dye or a polyester film comprising a dye and a pigment, having a haze of 6% or less, a light transmittance of 450nm of 4% or less, a light transmittance of 550nm of 20% or more, and a color tone (b) ^* ) The value of the water-soluble polymer is more than 50,

wherein the dye content (mass%) in the film is that the yellow dye is more than or equal to the red dye, the blue dye and the brown dye (mass%),

the dyes are 4 kinds of dyes which are yellow, red, blue and brown in combination.

2. An optical film according to claim 1, which is a laminated polyester film composed of 3 polyester resin layers containing polyester as a main component resin.

3. An optical film according to claim 1 or 2, wherein the dye content (mass%) in the film is yellow dye ∈ (red dye+blue dye+brown dye) ×10 (mass%).

4. An optical film according to claim 1 or 2, wherein the film has a functional layer (X) as a film surface layer on one side.

5. An optical film according to claim 4, wherein the film has a functional layer (Y) different from the functional layer (X) as a film surface layer on one side or the other side.

6. An optical film according to claim 5, wherein a functional layer (X) is provided as one film surface layer and the functional layer (Y) is provided as the other film surface layer, the functional layer (X) being an easy-to-adhere layer and the functional layer (Y) being an antistatic layer.

7. An optical film, wherein the optical film according to any one of claims 1 to 6 is used for mounting information terminal equipment.

8. A film laminate comprising a resin film laminated on one side of the optical film according to any one of claims 1 to 7 via an adhesive layer, wherein the film laminate has a film haze of 15% or less, a light transmittance of 1% or less at 450nm, a light transmittance of 15% to 30% at 550nm, and a color tone (b) ^* ) The value is 70 or more.

9. A film laminate comprising a resin film laminated on one surface of an optical film comprising a dye-containing or dye-and pigment-containing polyester film via an adhesive layer, wherein the film laminate has a film haze of 15% or less, a light transmittance of 1% or less at 450nm, a light transmittance of 15% to 30% at 550nm, and a color tone (b) ^* ) The value of the water-soluble polymer is more than 70,

wherein the dye content (mass%) of the polyester film is that the yellow dye is more than or equal to the red dye, the blue dye and the tea dye (mass%).

10. The film laminate according to claim 8 or 9, wherein the color tone (b) ^* ) The value is 80 or more.

11. The film laminate according to claim 8 or 9, wherein the resin film is a polyimide film.

12. A film laminate, wherein the film laminate according to any one of claims 8 to 11 is used for mounting an information terminal device.

13. A display unit using the optical film according to any one of claims 1 to 7 or the film laminate according to any one of claims 8 to 12.

14. A display unit is provided with the following components: the optical film according to any one of claims 1 to 7 or the film laminate according to any one of claims 8 to 12 is disposed on the opposite side from the viewing side with respect to the position of the LED light source.

15. The display unit according to claim 14, wherein a maximum value of an emission spectrum in a wavelength range of 400nm to 480nm is larger than a maximum value of an emission spectrum in a wavelength range of 500nm to 600nm for the LED light source.

16. A display unit according to claim 14 or 15, wherein the light emitted from the LED light source is designed to propagate at least in both directions, i.e. the upper side and the lower side, i.e. the visible side and the opposite side.

17. Root of Chinese characterThe display unit according to claim 14 or 15, wherein the optical film has a light transmittance (T1 _<550> ) Relative radiation intensity at 550nm wavelength with the LED light source (T2 _<550> ) Is a sum of (T1) _<550> +T2 _<550> ) More than 80%.

18. The display unit according to claim 14 or 15, wherein the optical film has a light transmittance (T1 _<450> ) Relative radiation intensity at 450nm wavelength with the LED light source (T2 _<450> ) Is a sum of (T1) _<450> +T2 _<450> ) Is less than 105%.

19. The display unit according to claim 14 or 15, wherein the film laminate has a light transmittance (T1 _<550> ) Relative radiation intensity at 550nm wavelength with the LED light source (T2 _<550> ) Is a sum of (T1) _<550> +T2 _<550> ) Is 75% or less.

20. The display unit according to claim 14 or 15, wherein the film laminate has a light transmittance (T1 _<450> ) Relative radiation intensity at 450nm wavelength with the LED light source (T2 _<450> ) Is a sum of (T1) _<450> +T2 _<450> ) Is less than 105%.

21. The display unit according to claim 19, wherein the film laminate has a light transmittance (T1 _<450> ) Relative radiation intensity at 450nm wavelength with the LED light source (T2 _<450> ) Is a sum of (T1) _<450> +T2 _<450> ) Is less than 105%.