WO2014021207A1 - 液晶ディスプレイ用白色ポリエステルフィルム - Google Patents

液晶ディスプレイ用白色ポリエステルフィルム Download PDF

Info

Publication number
WO2014021207A1
WO2014021207A1 PCT/JP2013/070293 JP2013070293W WO2014021207A1 WO 2014021207 A1 WO2014021207 A1 WO 2014021207A1 JP 2013070293 W JP2013070293 W JP 2013070293W WO 2014021207 A1 WO2014021207 A1 WO 2014021207A1
Authority
WO
WIPO (PCT)
Prior art keywords
film
layer
liquid crystal
polyester
crystal display
Prior art date
Application number
PCT/JP2013/070293
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
舩冨剛志
長谷川正大
井澤雅俊
Original Assignee
東レ株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 東レ株式会社 filed Critical 東レ株式会社
Priority to CN201380020258.1A priority Critical patent/CN104246545B/zh
Priority to JP2013543434A priority patent/JP6295664B2/ja
Publication of WO2014021207A1 publication Critical patent/WO2014021207A1/ja

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
    • B32B27/205—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents the fillers creating voids or cavities, e.g. by stretching
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
    • G02B5/0236—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element
    • G02B5/0247—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element by means of voids or pores
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0273—Diffusing elements; Afocal elements characterized by the use
    • G02B5/0284—Diffusing elements; Afocal elements characterized by the use used in reflection
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133605—Direct backlight including specially adapted reflectors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/24—All layers being polymeric
    • B32B2250/244—All polymers belonging to those covered by group B32B27/36
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/416—Reflective
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/514—Oriented
    • B32B2307/518—Oriented bi-axially
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/20—Displays, e.g. liquid crystal displays, plasma displays
    • B32B2457/202—LCD, i.e. liquid crystal displays

Definitions

  • the present invention relates to a white polyester film suitable for use as a liquid crystal display.
  • the present invention relates to a white polyester film which can be suitably used for a backlight device for image display and a reflection sheet of a lamp reflector, and particularly suitable for a reflector of a backlight device for image display.
  • a white polyester film has a uniform and high brightness for applications such as reflectors and reflectors for surface light source devices, back reflector sheets for lighting signs, and back reflector sheets for solar cells in flat image display systems used in liquid crystal displays, etc. It is widely used because of its characteristics such as thermal dimensional stability and low cost.
  • liquid crystal display devices for liquid crystal televisions and personal computers
  • the amount of heat generated in the device increases due to downsizing, high performance, and an increase in the amount of heat generated by the light source (for example, LED) used in the backlight of the liquid crystal display.
  • the light source for example, LED
  • the backlight was used for a long time, the phenomenon that the white film was deformed to wave and the screen was uneven was clarified.
  • the size of liquid crystal displays has increased, and the wavy phenomenon and screen unevenness have become major problems.
  • polyester film contains many inorganic particles such as barium sulfate, and uses light reflection at the interface between the polyester resin and the particles and the hollow interface of the fine cavities generated using the particles as nuclei.
  • Patent Document 1 a method of utilizing light reflection at the cavity interface of fine cavities generated by mixing an incompatible resin with polyester and using an incompatible resin as a nucleus
  • Patent Document 2 Inorganic contained in the polyester film, such as a method utilizing light reflection at the interface of the cavity formed inside by impregnating the polyester film with an inert gas in a pressure vessel (see Patent Document 3)
  • Patent Document 3 A method using a difference in refractive index between particles and polyester resin and a difference in refractive index between fine voids and polyester resin is widely used.
  • JP 2003-160682 A Japanese Patent Publication No. 8-16175 JP 2001-166295 A JP 2008-257229 A JP2011-209499A
  • the wavy phenomenon of the film and the screen unevenness caused by the use in the liquid crystal display, particularly in the liquid crystal display using the LED backlight are improved. This aims at maintaining high reflection performance during long-term use.
  • the white polyester film of the present invention that solves the above problems has the following configuration. That is, (A) A white polyester film having at least two layers of an A layer substantially free of voids and a B layer containing voids, wherein the white polyester film satisfies the following requirements (1) to (4) White polyester film for display, (1) Layer B contains incompatible resin in polyester and has bubbles, (2) The B layer has polyethylene terephthalate as a basic structure, contains at least one copolymer polyester, and the copolymer polyester is 1.0% by mass or more and 20.0% by mass or less based on the mass of the B layer.
  • the apparent density of the film is 0.5 g / cm 3 or more and 1.1 g / cm 3 or less
  • the thermal shrinkage measured by thermomechanical analysis at 40 ° C. to 100 ° C. in the longitudinal direction and the width direction of the film is ⁇ 0.5% or more and 0.0% or less.
  • White polyester film for liquid crystal display according to any one of (G) A backlight for a liquid crystal display, wherein the white polyester film for a liquid crystal display according to any one of (A) to (F) is used as a light reflecting material; (H) The backlight for the liquid crystal display according to (G), wherein the light source of the backlight is an LED system, It is.
  • the wavy phenomenon and screen nonuniformity of a film which arise by use inside a liquid crystal display, especially the inside of a liquid crystal display using LED backlight can be improved. Accordingly, high reflection performance can be maintained during long-term use.
  • the white polyester film of the present invention is a white polyester film having at least two layers of an A layer made of polyester and substantially free of voids and a B layer containing voids.
  • the A layer contains substantially no bubbles.
  • substantially containing no bubbles means a state of a layer having a porosity of less than 10%, and the thicknesses of the A layer and the B layer are substantially free of bubbles from the surface by observing a cross section with an electron microscope. The thickness up to the depth in the cross-sectional direction is determined, and the thickness of the layer containing substantially no bubbles is defined as the A layer thickness, and the thickness of the layer containing bubbles (cavities) is defined as the B layer thickness.
  • the layer A preferably contains inorganic particles in polyester and has a role of scattering light. In addition, it has a role of preventing light leakage to the back surface and a role of a support layer for stabilizing film formation.
  • the light scattering property of the A layer can be adjusted mainly by controlling the surface roughness, and other methods include, for example, a method of adding particles having different refractive indexes to a polyester resin.
  • the kind of inorganic fine particles to be contained in the A layer is not particularly limited, but preferably has a Mohs hardness of 3.0 or more, for example, calcium carbonate, titanium dioxide, zinc oxide, silicon dioxide, zinc sulfide. , Barium sulfate, alumina, talc and the like. These inorganic particles can be used alone or in combination depending on the necessity of imparting surface functions such as glossiness adjustment, whiteness adjustment, and light resistance.
  • the resin constituting the A layer and the B layer is polyester.
  • polyethylene terephthalate and polyethylene naphthalate are preferable.
  • additives such as an antioxidant and an antistatic agent may be added to the polyester.
  • the B layer is whitened by containing fine bubbles inside the film. Formation of fine bubbles can be achieved by finely dispersing a polymer (incompatible resin) incompatible with polyester in a film base material, for example, polyester, and stretching (for example, biaxial stretching).
  • a polymer incompatible resin
  • polyester in a film base material
  • stretching for example, biaxial stretching
  • the B layer needs to contain a resin incompatible with the polyester.
  • a resin incompatible with polyester (hereinafter sometimes abbreviated as incompatible resin), it may be a homopolymer or a copolymer, such as polyethylene, polypropylene, polybutene, polymethylpentene, etc.
  • a polyolefin resin, a cyclic polyolefin resin, a polystyrene resin, a polyacrylate resin, a polycarbonate resin, a polyacrylonitrile resin, a polyphenylene sulfide resin, a fluorine resin, or the like is preferably used. Two or more of these may be used in combination.
  • a resin having a large difference in critical surface tension from polyester and being hardly deformed by heat treatment after stretching is preferable, and specifically, a polyolefin-based resin is preferable.
  • the polyolefin resin include polyolefin resins such as polyethylene, polypropylene, polybutene, and polymethylpentene, cyclic polyolefin resins, and copolymers thereof.
  • a copolymer of ethylene and bicycloalkene, which is a cyclic olefin copolymer is particularly preferable.
  • the glass transition temperature of the incompatible resin is preferably 180 ° C. or higher and 220 ° C. or lower, and more preferably 190 ° C.
  • the glass transition temperature in the region where the glass transition temperature is lower than 180 ° C., voids developed during stretching may be deformed and crushed in the heat treatment process in the film manufacturing process. In particular, in a finely dispersed void with a reduced diameter, small deformation causes void disappearance, which may affect a decrease in the reflectance of the white polyester film, and thus a decrease in luminance. Further, in the region higher than 220 ° C., when melt kneading with the resin constituting the B layer, the incompatible resin is not sufficiently melted and fine dispersion may not be promoted.
  • the glass transition point is a temperature at which glass transition occurs in an amorphous solid material, and is abbreviated as Tg.
  • Tg is measured by reading the tangent of the base line in the DSC curve and the intersection of the tangent of the steeply descending position of the endothermic region due to glass transition.
  • Tg is in the above range, voids are less likely to disappear during heat treatment, and the rigidity of cycloolefin, which is a nucleus when expressing voids during stretching, is high, and the void generation rate is significantly increased. is there. Since voids can be finely stacked in multiple layers, it is effective in improving reflectivity and thus in luminance.
  • a cavity having the incompatible resin as a core is formed at the time of stretching, and light reflection occurs at the cavity interface.
  • preferable content of the incompatible resin contained in B layer is 5 mass% or more and 25 mass% or less. Since the number of cavities increases by increasing the content of the incompatible resin, the specific gravity decreases. It is preferable when the apparent specific gravity is 0.5 g / cm 3 or more and 1.1 g / cm 3 or less.
  • the incompatible resin to be contained in the B layer is dispersed in a matrix composed of a polyester resin with a number average particle size of 0.4 ⁇ m or more and 3.0 ⁇ m or less. It is preferable for obtaining film strength, and more preferably in the range of 0.5 ⁇ m or more and 1.5 ⁇ m or less.
  • the number average particle diameter here is a cross section of the film in the width direction (TD), and the B layer portion of the cross section is observed using a scanning electron microscope (FE-SEM) S-2100A manufactured by Hitachi, Ltd. It is the average value of the diameter when the area of 100 particles is calculated and converted into a perfect circle.
  • inorganic particles may be contained in the B layer, and examples thereof include calcium carbonate, titanium dioxide, zinc oxide, zirconium oxide, zinc sulfide, basic lead carbonate (lead white), and barium sulfate.
  • calcium carbonate, barium sulfate, titanium dioxide and the like which absorb less in the visible light range of 400 to 700 nm, are preferable from the viewpoints of reflection characteristics, concealability, production cost, and the like.
  • barium sulfate and titanium dioxide are the most preferable from the viewpoints of rollability of the film, long-term film-forming stability, and improved reflection characteristics.
  • the particle size of the inorganic particles it is preferable to use particles having a number average particle size of 0.1 ⁇ m or more and 3.0 ⁇ m or less in order to realize excellent reflectivity and concealability.
  • a copolyester for the B layer. Even a composition containing an inorganic substance at a high concentration in the B layer can be stably formed, and has a role as a dispersant for the incompatible resin in the B layer.
  • the copolymer polyester has a main dicarboxylic acid component of terephthalic acid, a main glycol component of ethylene glycol, and a copolymer component of aromatic carboxylic acid or aliphatic carboxylic acid such as isophthalic acid or naphthalene dicarboxylic acid, and tetra
  • the copolymer polyester used is based on polyethylene terephthalate, a copolymer of polyethylene terephthalate and isophthalic acid, a copolymer of polyethylene terephthalate and cyclohexanedimethanol, and a copolymer of polybutylene terephthalate and polytetramethylene terephthalate. It is preferable to contain at least two or more types of copolyesters selected from the coalescence.
  • the content of the copolyester contained in the B layer is 1% by mass or more and 20% by mass or less, and preferably 2% by mass or more and 15% by mass or less based on the mass of the B layer.
  • the amount is less than 1% by mass, the change in shrinkage stress with respect to the temperature change is small and the thermal dimensional stability is excellent, but the dispersibility of the incompatible resin is lowered and the reflection performance is lowered, and inorganic particles are contained.
  • the stretching stress of the film becomes so high that film formation may not be possible.
  • it contains many copolymer polyesters there exists a tendency for a thermal contraction rate to become high.
  • the thermal shrinkage rate measured by thermomechanical analysis at 40 ° C. to 100 ° C. does not satisfy ⁇ 0.5% or more and 0.0% or less, film undulation occurs in the backlight, The screen becomes uneven. In addition, film formation may be difficult.
  • the proportion of the copolymer component in the copolymer polyester is preferably 1 to 30 mol%, more preferably 3 to 25 mol%, based on the total dicarboxylic acid component or total diol component. If it is less than 1 mol%, the dispersibility of the incompatible resin is lowered, the reflection performance is lowered, and the stretching stress is increased when inorganic particles are contained, so that film formation may not be possible. On the other hand, if it exceeds 30 mol%, thermal dimensional stability may be lacking or film formation may be difficult.
  • the copolymerized polyester used in the present invention is preferably in the range of melting point 170 ° C. or higher and 230 ° C. or lower. More preferably, it is the range of 180 degreeC or more and 220 degrees C or less.
  • melting point of the thermoplastic polyester elastomer is less than 170 ° C., uniform dispersion may be difficult to obtain, and when used as a reflector, the luminance may decrease.
  • the temperature is higher than 230 ° C., the dispersion effect may not be recognized, which is not preferable.
  • the specific gravity of the white polyester film is 0.5 (g / cm 3 ) or more and 1.1 (g / cm 3 ) or less, preferably 0.55 (g / cm 3 ) or more and 1.05 (g / cm). 3 ) or less, more preferably 0.6 (g / cm 3 ) or more and 1.0 (g / cm 3 ) or less, in order to obtain a higher reflectance.
  • the specific gravity is less than 0.5 (g / cm 3 )
  • the film-forming stability is inferior.
  • the thermal shrinkage tends to be larger than that of the conventional polyester film.
  • it exceeds 1.1 (g / cm 3 ) the generation of fine bubbles may be insufficient.
  • the total thickness of the white polyester film is preferably from 50 ⁇ m to 500 ⁇ m, more preferably from 150 ⁇ m to 350 ⁇ m.
  • the total thickness of the white polyester film is preferably 50 ⁇ m or more from the viewpoint of reflectivity, and the thicker the thickness, the higher the rigidity and the less likely to bend in the housing.
  • the upper limit is not particularly limited, but is preferably 500 ⁇ m or less, more preferably 350 ⁇ m or less from the viewpoint of reflectance, workability, and cost. If the thickness exceeds 500 ⁇ m, an increase in reflectivity cannot be expected even if the thickness is greater than this, and workability (handling properties) deteriorates due to the increase in mass when working as a single wafer for incorporation into a backlight.
  • the relative reflectance at a wavelength of 560 nm of at least one surface of the white polyester film of the present invention is preferably 97.0% or more when used as a reflector.
  • the relative reflectance is more preferably 98.5% or more, further preferably 99.0% or more, and most preferably 99.5% or more.
  • the relative reflectance means that an integrating sphere is attached to a spectrophotometer (U-3310) manufactured by Hitachi High-Technologies, and the reflectance is 100% with reference to a standard white plate (aluminum oxide) attached to the spectrophotometer. It is a reflectance at that time.
  • thermomechanical analysis In the present invention, the thermal shrinkage measured by thermomechanical analysis at 40 ° C. to 100 ° C. in the longitudinal direction and the width direction of the film needs to be ⁇ 0.5% or more and 0.0% or less. .
  • thermomechanical analysis in the present invention refers to a value measured under the conditions described later using a thermomechanical analyzer (TMA / SS6000) manufactured by Seiko Instruments Inc. As for each data, at least one data per 1 ° C. is obtained, and the thermal shrinkage rate at each temperature is calculated using the following formula.
  • Thermomechanical analysis is a method of measuring the deformation of a substance as a function of temperature by applying a non-vibrating load while changing the temperature of the substance according to a regulated program, and shows the change of shrinkage stress with respect to temperature change. Is.
  • the measurement conditions are as follows.
  • an LED light source that is low in power consumption and capable of high output is arranged on the side, which is advantageous for thinning.
  • the backlight internal temperature near the LED light source is 100 It reaches around °C, and even at a distant part, it reaches around 60 °C.
  • the film is undulated inside the backlight when used as a reflector for backlight, resulting in unevenness of the screen.
  • the value of this thermal shrinkage is ⁇ 0.5% or more and 0.0% or less, more preferably ⁇ 0.4% or more and 0.0% or less.
  • Polyethylene terephthalate containing inorganic particles of silicon dioxide is supplied to Extruder A by a conventional method, and A layer / B layer / A layer is formed so that the polymer of Extruder A layer becomes both surface layers in the T die 3 layer die. A three-layer configuration was obtained.
  • the melted sheet is closely cooled and solidified by electrostatic force on a drum cooled to a drum surface temperature of 10 to 60 ° C., and the unstretched film is led to a group of rolls heated to 80 to 120 ° C. in the longitudinal direction. 2.8-4.0 times stretching.
  • the film after longitudinal stretching is subsequently subjected to stretching in the direction orthogonal to the longitudinal direction (hereinafter referred to as the transverse direction), heat setting, and thermal relaxation to form a biaxially oriented film. While running.
  • the transverse stretching process starts from a temperature higher than the glass transition temperature (Tg) of the polyester. Then, the temperature is raised to (5 to 70) ° C. higher than Tg.
  • the temperature increase in the transverse stretching process may be continuous or stepwise (sequential), but it is usually preferable to increase the temperature sequentially.
  • the transverse stretching zone of the tenter is divided into a plurality along the film running direction, and the temperature is raised by flowing a heating medium having a predetermined temperature for each zone.
  • the transverse stretching ratio is preferably 2.5 to 4.5 times, more preferably 2.8 to 3.9 times, although it depends on the required characteristics of the application. If it is less than 2.5 times, the thickness unevenness of the film is deteriorated and a good film cannot be obtained, and if it exceeds 4.5 times, breakage tends to occur during film formation.
  • a cavity can be developed with a resin or an air-forming inorganic particle incompatible with polyester as a nucleus.
  • the white polyester film of the present invention may be stretched by either the sequential biaxial stretching method or the simultaneous biaxial stretching method.
  • the obtained biaxially stretched film In order to complete the crystal orientation of the obtained biaxially stretched film and to impart flatness and thermal dimensional stability, it is subsequently heat-set in a tenter at a temperature of 180 to 220 ° C. for 1 to 30 seconds, After gradually cooling uniformly, cool to room temperature and wind up. Thereafter, heat treatment is applied to the obtained film. During the heat treatment step, a relaxation treatment of 0.5 to 10% may be performed in the horizontal direction or the vertical direction as necessary.
  • the heat setting and heat treatment steps are important steps for obtaining the white polyester film for liquid crystal display of the present invention, and will be described in detail below.
  • the white polyester film for liquid crystal display of the present invention forms cavities around the incompatible component, and thus the apparent density is lower than that of the conventional polyester film.
  • This void-containing polyester film tends to have a higher thermal shrinkage rate than conventional polyester films.
  • it is effective to increase the temperature of heat setting after transverse stretching. Therefore, it is preferable to perform the heat setting at 180 to 220 ° C. More preferably, it is 190 to 210 ° C.
  • the polyester and the incompatible resin are softened, and the cavity is crushed or disappears, so that the apparent specific gravity is increased and the original purpose cannot be achieved. End up. Since the polyester film has low air permeability, there are cases where the cavity is not sufficiently filled with air (that is, close to a vacuum state) immediately after the cavity is generated by transverse stretching. In this state, when the polyester and the incompatible resin are softened by heat fixation at a high temperature, the cavity is crushed because the cavity is in a vacuum state. If the cavity is collapsed, the reflectivity will decrease.
  • heat treatment step a method (heat treatment A: in-line treatment) performed during the production of the biaxially stretched polyester film is preferable from the viewpoint of production cost, but the film once formed is again passed through an oven and subjected to a relaxation treatment ( Heat treatment B: off-line treatment) may be performed.
  • heat treatment A in-line treatment
  • Heat treatment B off-line treatment
  • Heat treatment A In-line treatment
  • a cutting blade is installed in the vicinity where the edge is opened from the clip at the tenter outlet, the film edge is cut and removed, and the film is once cooled to room temperature.
  • the film take-off speed is reduced to heat-treat and relax the entire width of the film removed from the clip in the longitudinal direction.
  • the speed of the roll group on the winding side is adjusted.
  • the heat treatment is particularly preferable because the thermal shrinkage rate measured by TMA is set to -0.5% or more and 0.0% or less.
  • the speed of the roll group is reduced with respect to the film line speed of the tenter, preferably 0.1 to 1.5%, more preferably 0.2 to 1.2%, particularly preferably 0.3.
  • the film is relaxed by reducing the speed by ⁇ 1.0% to adjust the heat shrinkage in the machine direction.
  • the temperature of the environment for deferment is preferably a temperature not higher than the glass transition point (Tg) of the polyester, specifically 70 ° C. or lower, more preferably 55 ° C. or lower, and further preferably 40 ° C. or lower. . If the temperature exceeds 70 ° C., the polyester and / or the incompatible resin may be softened, the effect of the subsequent heat treatment is reduced, and the cost is not preferable.
  • the lower limit of the temperature is not particularly limited, but is preferably ⁇ 5 ° C. or higher from the viewpoint of cost.
  • the standing time is preferably 24 hours or more in order to sufficiently fill the cavity with air.
  • the film as described above fill the cavity with air, and heat-treat in an oven.
  • the heat treatment is particularly preferable because the thermal shrinkage rate measured by TMA is -0.5% or more and 0.0% or less.
  • the temperature of the heat treatments A and B is preferably not higher than the melting point (Tm) of the polyester, specifically 100 to 200 ° C, more preferably 120 to 180 ° C. If the temperature of the heat treatment is lower than 100 ° C., the thermal shrinkage rate is not sufficiently reduced, and if it is higher than 200 ° C., the apparent density is not sufficiently lowered and the flatness of the film is deteriorated.
  • the heat treatment time is preferably 5 to 50 seconds, more preferably 10 to 40 seconds. If the heat treatment time is shorter than 5 seconds, the thermal shrinkage rate is not sufficiently reduced, and if it is longer than 50 seconds, the specific gravity is not sufficiently lowered, which is not preferable. By such heat treatment, it is possible to achieve both high reflection performance and thermal dimensional stability, which could not be achieved by conventional methods.
  • the white polyester film of the present invention thus obtained can improve the brightness of the liquid crystal backlight, and even when used for a long time, there is no splatter of the reflector, and the decrease in reflectance is small. It can be conveniently used as a reflector for surface light sources and reflectors of edge lights and direct type lights.
  • the obtained white polyester film for reflecting a liquid crystal display of the present invention can maintain high luminance particularly when used as a reflector of a side light type and direct light type liquid crystal display using LEDs.
  • the physical property value evaluation method and the effect evaluation method of the present invention are as follows.
  • the film thickness was measured according to JIS C2151-2006.
  • the film was cut in the width direction (TD) without crushing in the thickness direction using a microtome to obtain a slice sample.
  • the section of the section sample was imaged at a magnification of 3000 times using a scanning electron microscope (FE-SEM) S-2100A manufactured by Hitachi, Ltd., and the laminate thickness was measured from the image and the thickness and thickness ratio of each layer were calculated.
  • voids bubbles
  • the area of the portion observed as bubbles was divided by the area of the observed layer and multiplied by 100 to obtain the porosity.
  • thermomechanical analysis (TMA) Measurement was performed under the following conditions using a thermomechanical analyzer (TMA / SS6000) manufactured by Seiko Instruments Inc. Each data was such that at least one data per 1 ° C. was obtained, and the thermal shrinkage at each temperature was calculated using the following formula.
  • Luminance unevenness (screen unevenness) and new brightness product Hisense Japan Co., Ltd. 32 type liquid crystal TV LHD32K15JP The reflective film pasted in the backlight was changed to the reflective plate taken out in the above (4) and turned on. In this state, after waiting for 1 hour to stabilize the light source, the liquid crystal screen was photographed with a CCD camera (DXC-390, manufactured by SONY), and the image was captured with an eye scale manufactured by an image analyzer, Eye System. Thereafter, the brightness level of the photographed image was controlled to 30,000 steps to be automatically detected and converted to brightness.
  • CCD camera DXC-390, manufactured by SONY
  • Brightness unevenness (%) (maximum luminance value ⁇ minimum luminance value) / average luminance value ⁇ 100
  • Lumirror (registered trademark) # 250E6SL manufactured by Toray Industries, Inc. was used as a reference sample (100%), and the following evaluation results were obtained.
  • A The film can be stably formed for 24 hours or more.
  • B The film can be stably formed for 12 hours or more and less than 24 hours.
  • C Breakage occurs within 12 hours, and stable film formation is not possible. Said A and B were set as the pass.
  • the peak area intensity of absorption peculiar to each component is obtained, and the molar ratio of the blend is calculated from the ratio and the number of protons. Further, the mass ratio is calculated from the formula amount corresponding to the unit unit of the polymer. Thus, the mass fraction and structure of each component were specified.
  • Example 1 Using polyethylene terephthalate having a color tone of polyethylene terephthalate after polymerization (measured by JIS K7105-1981, stimulus value direct reading method) of L value 62.8, b value 0.5, haze 0.2%, polyethylene terephthalate 94 mass Part, 0.5 part by mass of (PBT / PTMG) copolymer of polybutylene terephthalate and polytetramethylene glycol (trade name: Hytrel manufactured by Toray DuPont), 33 mol% of 1,4-cyclohexanedimethanol with respect to the diol component 0.5 parts by mass of copolymerized polyethylene terephthalate (33 mol% CHDM copolymerized PET) and 5 parts by mass of cycloolefin copolymer (trade name: TOPAS manufactured by Polyplastics Co., Ltd.) having a glass transition temperature of 210 ° C. are prepared. After mixing and drying at 180 ° C for 3 hours It was fed
  • the unstretched film obtained by cooling and solidifying this film with a cooling drum having a surface temperature of 25 ° C. was led to a roll group heated to 85 to 98 ° C., longitudinally stretched 3.4 times in the longitudinal direction, and cooled by a roll group at 21 ° C. . Subsequently, the film was stretched by 3.6 times in a direction perpendicular to the longitudinal direction in an atmosphere heated to 120 ° C. while being guided to a tenter while holding both ends of the longitudinally stretched film with clips. Thereafter, heat setting at 190 ° C.
  • Example 2 to 20 A white polyester film was obtained in the same manner as in Example 1 except that the raw material composition of the A layer and B layer, the film forming conditions, and the heat treatment conditions were changed as described in Tables 1 and 2. In all examples, the film shape, luminance unevenness, and luminance were good.
  • Example 1 A film having a thickness of 225 ⁇ m was obtained in the same manner as in Example 1 except that the raw material composition of the A layer and the B layer and the film forming conditions were changed as described in Table 3. Since the content of the copolymerization component of the B layer was large and heat treatment was not performed, the film shape and luminance unevenness were insufficient.
  • a white polyester film was obtained in the same manner as in Example 1 except that the raw material composition of the A layer and the B layer and the film forming conditions were changed as described in Table 3. Although the content of the copolymerization component in the B layer is small, since the heat treatment was not performed, the film shape, luminance unevenness, and film formation stability were insufficient.
  • Example 7 A white polyester film was obtained in the same manner as in Example 1 except that the raw material composition of the A layer and the B layer and the film forming conditions were changed as described in Table 3. Since the content of the copolymerization component in the B layer was large, heat treatment was performed, but the film shape and luminance unevenness were insufficient.
  • PET Polyethylene terephthalate
  • PET / I Polyethylene terephthalate copolymerized with 18 mol% isophthalic acid
  • PET / CHDM polyethylene-1,4-cyclohexylenedimethylene terephthalate (polyethylene terephthalate copolymer in which 33 mol% of 1,4-cyclohexanedimethanol is copolymerized with ethylene glycol)
  • PBT / PTMG Polyester ether elastomer mabutylene / poly (alkylene ether) phthalate (copolymer having 30 mol% of alkylene glycol with respect to butylene terephthalate) (trade name: Hytrel manufactured by Toray DuPont)
  • PET / I / PEG a copolymer obtained by copolymerizing 10 mol% of polyethylene terephthalate isophthalic acid and 5 mol% of polyethylene
  • the white polyester film for a liquid crystal display of the present invention can be suitably used for a backlight.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical & Material Sciences (AREA)
  • Laminated Bodies (AREA)
  • Optical Elements Other Than Lenses (AREA)
  • Liquid Crystal (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
PCT/JP2013/070293 2012-07-30 2013-07-26 液晶ディスプレイ用白色ポリエステルフィルム WO2014021207A1 (ja)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN201380020258.1A CN104246545B (zh) 2012-07-30 2013-07-26 液晶显示器用白色聚酯膜
JP2013543434A JP6295664B2 (ja) 2012-07-30 2013-07-26 液晶ディスプレイ用白色ポリエステルフィルム、その製造方法及び液晶ディスプレイ用バックライト

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2012-168128 2012-07-30
JP2012168128 2012-07-30

Publications (1)

Publication Number Publication Date
WO2014021207A1 true WO2014021207A1 (ja) 2014-02-06

Family

ID=50027884

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2013/070293 WO2014021207A1 (ja) 2012-07-30 2013-07-26 液晶ディスプレイ用白色ポリエステルフィルム

Country Status (4)

Country Link
JP (2) JP6295664B2 (zh)
CN (1) CN104246545B (zh)
TW (1) TW201410465A (zh)
WO (1) WO2014021207A1 (zh)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015086241A (ja) * 2013-10-28 2015-05-07 帝人デュポンフィルム株式会社 白色ポリエステルフィルム
WO2018021211A1 (ja) * 2016-07-27 2018-02-01 東洋紡株式会社 白色ポリエステル系フィルム、積層体及び包装袋
JP2020109515A (ja) * 2020-02-03 2020-07-16 東洋紡フイルムソリューション株式会社 大型ディスプレイ用白色反射フィルム
US20220161534A1 (en) * 2019-03-28 2022-05-26 Toray Advanced Materials Korea Inc. Biaxially oriented polyester reflective film and manufacturing method therefor

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014021207A1 (ja) * 2012-07-30 2014-02-06 東レ株式会社 液晶ディスプレイ用白色ポリエステルフィルム
CN104793274A (zh) * 2014-12-23 2015-07-22 南京亚博联新材料科技股份有限公司 一种光扩散用聚酯薄膜
KR102397408B1 (ko) * 2016-06-24 2022-05-11 코오롱인더스트리 주식회사 폴리에스테르 다층필름 및 이의 제조방법
KR102272984B1 (ko) * 2020-06-04 2021-07-05 도레이첨단소재 주식회사 백색 폴리에스테르 필름 및 그의 제조방법

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007261260A (ja) * 2006-03-02 2007-10-11 Toray Ind Inc 反射板用白色積層ポリエステルフィルム
JP2008030459A (ja) * 2006-07-07 2008-02-14 Toray Ind Inc 反射シート用白色積層ポリエステルフィルム
WO2008093623A1 (ja) * 2007-01-31 2008-08-07 Toray Industries, Inc. 白色ポリエステルフィルムおよび反射シート
JP2008257229A (ja) * 2007-03-14 2008-10-23 Toray Ind Inc 反射板用ポリエステルフィルム
JP2009035670A (ja) * 2007-08-03 2009-02-19 Toray Ind Inc 金属板被覆用ポリエステルフィルム
JP2012081748A (ja) * 2010-09-17 2012-04-26 Toray Ind Inc 積層フィルムおよびそれを用いた自動車用窓ガラス

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7273640B2 (en) * 2003-11-21 2007-09-25 Rohm And Haas Denmark Finance A/S Highly reflective optical element
CN101193737B (zh) * 2005-06-09 2010-11-24 东丽株式会社 双轴拉伸聚酯膜的制造方法
JP4784380B2 (ja) * 2006-04-27 2011-10-05 東洋紡績株式会社 積層ポリエステルフィルム及び鏡面反射フィルム
KR101086093B1 (ko) * 2006-06-30 2011-11-25 도요 보세키 가부시키가이샤 성형용 적층 폴리에스테르 필름 및 그 제조방법
JP4609580B2 (ja) * 2006-09-06 2011-01-12 東洋紡績株式会社 成型用ポリエステルフィルムの製造方法
CN102782532B (zh) * 2010-03-23 2015-04-15 东丽株式会社 白色聚酯膜、使用其的光反射板以及液晶显示器用背光源
JP5672735B2 (ja) * 2010-03-26 2015-02-18 東レ株式会社 空洞含有ポリエステルフィルム
JP2011209499A (ja) * 2010-03-30 2011-10-20 Toray Ind Inc 面光源反射板用白色ポリエステルフィルム及びそれを用いた液晶ディスプレイ用面光源反射板
JP2012137618A (ja) * 2010-12-27 2012-07-19 Toray Ind Inc 面光源反射板用白色ポリエステルフィルム
WO2014021207A1 (ja) * 2012-07-30 2014-02-06 東レ株式会社 液晶ディスプレイ用白色ポリエステルフィルム

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007261260A (ja) * 2006-03-02 2007-10-11 Toray Ind Inc 反射板用白色積層ポリエステルフィルム
JP2008030459A (ja) * 2006-07-07 2008-02-14 Toray Ind Inc 反射シート用白色積層ポリエステルフィルム
WO2008093623A1 (ja) * 2007-01-31 2008-08-07 Toray Industries, Inc. 白色ポリエステルフィルムおよび反射シート
JP2008257229A (ja) * 2007-03-14 2008-10-23 Toray Ind Inc 反射板用ポリエステルフィルム
JP2009035670A (ja) * 2007-08-03 2009-02-19 Toray Ind Inc 金属板被覆用ポリエステルフィルム
JP2012081748A (ja) * 2010-09-17 2012-04-26 Toray Ind Inc 積層フィルムおよびそれを用いた自動車用窓ガラス

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015086241A (ja) * 2013-10-28 2015-05-07 帝人デュポンフィルム株式会社 白色ポリエステルフィルム
WO2018021211A1 (ja) * 2016-07-27 2018-02-01 東洋紡株式会社 白色ポリエステル系フィルム、積層体及び包装袋
JPWO2018021211A1 (ja) * 2016-07-27 2019-05-09 東洋紡株式会社 白色ポリエステル系フィルム、積層体及び包装袋
US20220161534A1 (en) * 2019-03-28 2022-05-26 Toray Advanced Materials Korea Inc. Biaxially oriented polyester reflective film and manufacturing method therefor
JP2020109515A (ja) * 2020-02-03 2020-07-16 東洋紡フイルムソリューション株式会社 大型ディスプレイ用白色反射フィルム

Also Published As

Publication number Publication date
JP6295664B2 (ja) 2018-03-20
TWI562889B (zh) 2016-12-21
JPWO2014021207A1 (ja) 2016-07-21
JP6624184B2 (ja) 2019-12-25
TW201410465A (zh) 2014-03-16
CN104246545A (zh) 2014-12-24
JP2018063437A (ja) 2018-04-19
CN104246545B (zh) 2017-05-24

Similar Documents

Publication Publication Date Title
JP6624184B2 (ja) 液晶ディスプレイ用白色ポリエステルフィルム、その製造方法及び液晶ディスプレイ用バックライト
JP4548430B2 (ja) 反射板用白色積層ポリエステルフィルム
JP6185537B2 (ja) 白色反射フィルムの製造方法
JP5045851B2 (ja) 白色ポリエステルフィルム、それを用いた光反射板および液晶ディスプレイ用バックライト
KR101813543B1 (ko) 백색 필름 및 그것을 사용한 면광원
EP2610651A2 (en) Process for producing white layered film, and white layered polyester film
KR102590694B1 (ko) 백색 반사 필름
JP2012135952A (ja) 白色ポリエステルフィルム
JP2015030232A (ja) 白色ポリエステルフィルムおよび、それを用いた光反射板
JP5817165B2 (ja) 反射板用白色積層ポリエステルフィルムおよびバックライト装置
KR101561288B1 (ko) 저광택 백색 폴리에스테르 필름과 이의 제조방법 및 이를 이용한 반사시트
KR102538884B1 (ko) 트레이형상을 갖는 반사판
CN107111014B (zh) 直下型面光源用白色反射膜及使用该膜的直下型面光源
JPWO2018025663A1 (ja) 成形用白色ポリエステルフィルム及びそれを用いた白色樹脂成形体
JP2014126638A (ja) 液晶ディスプレイ用反射フィルム
JP2016093947A (ja) 液晶ディスプレイ用白色ポリエステルフィルムおよび、それを用いた液晶ディスプレイ用バックライト
WO2016035536A1 (ja) 液晶ディスプレイ用白色ポリエステルフィルム、およびそれを用いた液晶ディスプレイ用バックライト
KR101350748B1 (ko) 액정 디스플레이 반사판용 적층 백색 폴리에스테르 필름
KR101610822B1 (ko) 저광택 백색 폴리에스테르 필름과 이의 제조방법 및 이를 이용한 반사시트
KR101848452B1 (ko) 다층 백색 다공성 폴리에스테르 필름
JP2015069020A (ja) 白色反射フィルム
KR101915662B1 (ko) 백색 폴리에스테르 반사필름의 제조방법 및 그에 의한 백색 폴리에스테르 반사필름
JP5785202B2 (ja) 白色反射フィルム
JP2018169456A (ja) 白色反射フィルム
JP2019093711A (ja) ポリエステルフィルムおよび樹脂成形体

Legal Events

Date Code Title Description
ENP Entry into the national phase

Ref document number: 2013543434

Country of ref document: JP

Kind code of ref document: A

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 13825137

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 13825137

Country of ref document: EP

Kind code of ref document: A1