Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V7/00—Reflectors for light sources
  • F21V7/22—Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors
  • F21V7/28—Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors characterised by coatings
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/08—Mirrors
• • 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
  • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
  • B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
  • F21K2/00—Non-electric light sources using luminescence; Light sources using electrochemiluminescence
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
  • F21S2/00—Systems of lighting devices, not provided for in main groups F21S4/00 - F21S10/00 or F21S19/00, e.g. of modular construction
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V7/00—Reflectors for light sources
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V7/00—Reflectors for light sources
  • F21V7/22—Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors
  • F21V7/24—Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors characterised by the material

Definitions

• the present invention relates to a white reflective film for improving luminance unevenness of a liquid crystal backlight. More particularly, the present invention relates to a white reflective film suitably used for backlights for edge light type liquid crystal displays and surface light sources for lighting such as signboards and vending machines.
• Liquid crystal displays use backlights that illuminate liquid crystal cells, and are divided into direct and edge light systems.
• direct type many cold cathode fluorescent lamps and light emitting diodes (LEDs) are arranged directly under the screen and are mainly used for TV applications that require high brightness.
• edge light type the light source is arranged at the edge of the screen. Since a light source plate is used as a surface light source, it can be thinned, and is used for tablets, notebook computers, desktop monitors, and TV applications that require thinning.
• a porous white film formed of bubbles is generally used (Patent Document 1).
• the reflection film used for the edge light type is required not only to have high reflection performance but also to be compatible with the light guide plate.
• an object of the present invention is to provide a film having impact resistance durability, excellent reflectivity, and surface shape, which could not be achieved by the above-described conventional studies, at low cost.
• a white reflective film for an edge-type backlight that satisfies the following (i) to (iii): (I) It is a laminated film of two or more layers including at least a surface layer (A) and a base material layer (B) containing bubbles. (Ii) The center plane average roughness (SRa) of the surface of the surface layer (A) is 90 nm or more and less than 300 nm. (Iii) The surface layer (A) has a domain composed of a polymer different from the polymer constituting the matrix.
• the ratio of the length in the thickness direction to the length in the longitudinal direction when the shape of the domain described in (1) or (2) is a cross section of the surface layer (A) is 1: 3 or more
• the surface layer (A) is composed of two or more kinds of polymers, and the difference in temperature-falling crystallization temperature (Tmc) is 10 ° C. or more and less than 40 ° C., according to any one of (1) to (6) White reflective film for edge type backlight.
• a backlight for a liquid crystal display comprising the film according to any one of (1) to (7).
• a polymer having a special structure is selected without adding particles to the surface layer (A) on the side of the white reflective film in contact with the light guide plate (the reflective surface side in use, the side facing the light guide plate).
• the surface roughness within a specific range, it is possible to provide a white reflective film that suppresses scratches on the light guide plate in the impact test of the backlight.
• the white reflective film obtained in the present invention suppresses scratches on the light guide plate when used in an edge light type backlight provided with an LED light source and a surface light source for illumination, and thereby more uneven brightness than before. Can be reduced, which is preferable.
• the present invention as a result of intensive studies on the white reflection film that suppresses scratches on the light guide plate in the impact test in the edge light type backlight, the side that contacts the light guide plate of the white reflection film (the reflective surface side in use)
• the side that contacts the light guide plate of the white reflection film the reflective surface side in use
• the above problems can be solved all at once.
• the brightness unevenness means the following unevenness that is visually observed when the backlight is turned on.
• white spot unevenness is an ellipsoid having a major axis of less than 5 cm that is visually observed when the backlight is turned on. This means a spot-like unevenness.
• the white reflective film of the present invention is composed of a surface layer (A) and a base material layer (B) containing bubbles, and in view of the ease and effect of film formation, a structure of two or more layers is necessary, and a three-layer structure is required. preferable.
• a form in which the base layer (B) is protected by the surface layer (A) that is, a three-layer structure of the surface layer (A) / base layer (B) / surface layer (A) is preferable.
• a core layer part is a base material layer (B)
• the surface layer part of one side or both sides is a surface layer (A).
• the white reflective film of the present invention needs to have bubbles inside the base material layer (B) for whiteness and reflection characteristics, but is incompatible with the polyester or polypropylene constituting the base material layer (B). Bubbles can be formed by containing various components and biaxially stretching.
• polyesters using barium sulfate as an incompatible component described in Japanese Patent No. 3734172 and polypropylenes using titanium oxide as an incompatible component described in Japanese Patent Application Laid-Open No. 2012-158167 are disclosed.
• organic incompatible resins specific examples of organic substances include linear, branched, or cyclic polyolefins such as polyethylene, polypropylene, polybutene, polymethylpentene, and cyclopentadiene.
• the polyolefin may be a homopolymer or a copolymer, and may be used in combination of two or more.
• polypropylene and polymethylpentene are preferably used as crystalline polyolefins, and cycloolefin copolymers and the like are preferably used as amorphous polyolefins. .
• the amount of the incompatible component added is preferably 5 to 50% by mass when the total mass of the base layer (B) containing bubbles is 100% by mass, and preferably 5 to 30% by mass. % Is more preferable. If the content of the incompatible component is less than 5% by mass, sufficient bubbles are not generated inside the film, and the whiteness and light reflection characteristics may be inferior. On the other hand, if the content of incompatible components exceeds 50% by mass, the strength of the film is reduced, breakage during stretching tends to occur, and inconvenience such as generation of powder may occur during post-processing. . By setting the content within this range, sufficient whiteness, reflectivity, and lightness can be exhibited.
• the center plane average roughness (SRa) of the surface of the surface layer (A) must be 90 nm or more and less than 300 nm, preferably 120 to 300 nm, most preferably 120 to 250 nm. is there.
• the thickness is less than 90 nm, the glossiness becomes high, dust adhering to the surface is easily visible, and uneven brightness, particularly white spots, easily occur in the edge light type backlight.
• the thickness is 300 nm or more, the surface of the surface layer (A) is shaved during a vibration test with the light guide plate, and a problem of transferring to the light guide plate dots is likely to occur.
• the center plane average roughness of the surface of the surface layer (A) is a value measured by the following method. Based on JIS B0601 (2001), the center surface average roughness (SRa) was measured using a stylus type surface roughness meter (model number: ET 4000A) manufactured by Kosaka Laboratory. The conditions were as follows, and the average value of five measurements was taken as the value.
• the surface layer (A) has a domain composed of a polymer different from the polymer constituting the matrix]
• the surface layer (A) needs to have a domain composed of a polymer different from the polymer constituting the matrix so that luminance unevenness that occurs when contacting the light guide plate or luminance unevenness after the impact test does not occur.
• the domain can be easily recognized from the contrast of the cross section SEM of the surface layer (A).
• the polymer domain when the polymer domain is not provided, for example, when the center surface average roughness (SRa) of the present application is achieved with inorganic particles, the light guide plate is scratched in an impact test, and luminance unevenness occurs. Further, when the center surface average roughness (SRa) is achieved with the organic particles, the organic particles drop off and adhere to the light guide plate in an impact test, and uneven brightness occurs.
• SRa center surface average roughness
• the domain interface thickness is preferably 20 nm or more and 1,000 nm or less.
• the thickness is less than 20 nm, voids are likely to be generated between the matrix and the domain, and the matrix may be rubbed and adhered to the light guide plate in an impact test, resulting in luminance unevenness.
• it is larger than 1,000 nm, it may become too compatible and a sufficient surface roughness may not be obtained.
• a more preferable range of the domain thickness is 50 nm or more and 1,000 nm or less, and more preferably 50 nm or more and 500 nm or less.
• the shape of the domain in the present invention is preferably a substantially flat shape co-stretched together with the matrix.
• the ratio is preferably from 1: 3 to 1:50.
• the ratio is less than 1: 3, the domains are not co-stretched, and voids are likely to be generated.
• the impact test may cause the matrix to turn and adhere to the light guide plate, resulting in uneven brightness.
• larger than 1:50 it may be extended
• a more preferable range of the domain shape is 1: 5 or more and 1:50 or less, and more preferably 1:10 or more and 1:50 or less.
• the Tg difference between the polymer constituting each of the matrix and the domain there is a method of controlling the Tg difference between the polymer constituting each of the matrix and the domain. Specifically, it is preferable to control the Tg difference between the polymers constituting the matrix and the domain to be 10 ° C. or more and less than 40 ° C.
• the surface roughness shape formed by having a domain composed of a polymer different from the polymer constituting the matrix is not a steep protrusion formed by particles or the like, but a gentle protrusion. It is low, and the brightness unevenness and the brightness unevenness after the impact test can be greatly suppressed.
• the thickness of the surface layer (A) is preferably 4 ⁇ m or more and 12 ⁇ m or less. If it is less than 4 ⁇ m, there are many tears at the time of film formation, and handling properties may be lowered, or sufficient surface irregularities may not be formed. On the other hand, if it is thicker than 12 ⁇ m, the luminance may be lowered. More preferably, it is 6 ⁇ m or more and 12 ⁇ m or less.
• main protrusions have a polymer as a nucleus so that luminance unevenness after an impact test does not occur.
• a state in which the layer (A) is formed without being compatible with each other in an extruder or a film forming process is preferable.
• the standard for not being compatible is, for example, that a temperature drop crystallization temperature (Tmc) difference of the surface layer (A) is observed.
• the cooling crystallization temperature (Tmc) is preferably 10 ° C. or higher and 40 ° C. or lower. If the temperature exceeds 40 ° C., cold crystallization is promoted, resulting in hard surface irregularities, which may cause a problem of scraping the light guide plate. More preferably, it is 15 degreeC or more and less than 35 degreeC.
• Examples of the method for suppressing the compatibility include, in the case of polyester, a method of adding a so-called transesterification inhibitor that suppresses the activity of the polymer polymerization catalyst, or a method of suppressing the thermal history during the film forming process.
• polyester or polyolefin with alicyclic structure Of the two or more types of polymers in the present invention, at least one type preferably contains a polyester or polyolefin having an alicyclic structure.
• a polyester or polyolefin having an alicyclic structure when polyesters or polyolefins having alicyclic structures with different compatibility are used, appropriate surface irregularities are easily formed.
• an alicyclic structure a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring are preferable.
• Dimethyl terephthalate as the acid component
• 1,3-cyclopropanediol 1,3-cyclobutanediol
• 1,3-cyclopentanediol 1,4-cyclohexanedimethanol
• 200 ppm of butyltin tris 2- Polyester pellets or polyolefin pellets having an alicyclic structure can be obtained by performing a polycondensation reaction in the presence of ethylhexanoate).
• polyester having a cyclobutane ring “TRITAN” (registered trademark) (manufactured by Eastman Chemical Company), as a polyester having a cyclohexane ring, EASTAL ”(registered trademark) (manufactured by Eastman Chemical Company), as a polyolefin having a cyclopentane ring “Zeonor” (registered trademark) (manufactured by Nippon Zeon Co., Ltd.) and the like can be preferably used.
• the addition amount of the polyester (B) having an alicyclic structure is not particularly limited, but is preferably 10% by mass or more and 40% by mass or less with respect to 100% by mass of the total mass of the surface layer (A). Especially preferably, it is 15 to 35 mass%. If it is less than 10% by mass, luminance unevenness, particularly white spots, easily occur in the edge light type backlight.
• a diol such as ethylene glycol or butanediol and a dicarboxylic acid component such as terephthalic acid or isophthalic acid are copolymerized.
• Polyester can be used.
• PET polyethylene terephthalate
• PET-I copolymerized PET
• ethylene glycol, isophthalic acid and terephthalic acid can be used for the purpose of imparting film forming stability and facilitating the formation of surface irregularities.
• the addition amount of PET-I is preferably 20% by weight or more and less than 50% by weight when the surface layer (A) is 100% by weight. If it is less than 20% by weight, the effect of film formation stability may be low, or the effect of forming surface irregularities may be low. On the other hand, if it is 50% by weight or more, the heat resistance may decrease.
• the particles of the present invention refer to inorganic particles or organic particles.
• inorganic particles include titanium dioxide, calcium carbonate, barium sulfate, and silica.
• organic particles include acrylic, polystyrene, and nylon.
• the gloss difference between 20 ° and 85 ° of the surface layer (A) in the present invention is preferably 50% or more. Since the difference in glossiness is large, light can be efficiently returned to the front of the display as a light reflecting film. More preferably, it is 65% or more, More preferably, it is 80% or more.
• the example is demonstrated about the manufacturing method of the biaxially stretched film of this invention, this invention is not limited only to this example.
• polyester or polypropylene and polyester (B) having an alicyclic structure and a mixture containing various additives as necessary are sufficiently vacuum-dried and supplied to a heated extruder.
• the addition of the polyester (B) having an alicyclic structure may be performed using a master chip prepared by uniform melt melting and kneading in advance, or may be directly supplied to a kneading extruder.
• the base material layer (B) containing a bubble, the mixture containing a component incompatible with polyester or polypropylene, and a dispersing agent as needed is fully vacuum-dried, and is supplied to the heated extruder.
• the incompatible component may be added using a master chip prepared by melt-kneading uniformly in advance, or directly supplied to a kneading extruder.
• melt-extrude after filtering through a filter having a mesh of 40 ⁇ m or less, to introduce into a T-die die and obtain a molten sheet by extrusion molding.
• the melted sheet is closely cooled and solidified by static electricity on a drum cooled to a surface temperature of 10 to 60 ° C. to produce an unstretched A / B / A three-layer film.
• the unstretched three-layer film is led to a roll group heated to 70 to 120 ° C., preferably 70 to 100 ° C., and stretched 2.5 to 4 times in the longitudinal direction (longitudinal direction, that is, the traveling direction of the film), 20 Cool with rolls at a temperature of ⁇ 50 ° C.
• the film is guided to a tenter while holding both ends of the film with clips, and stretched 2.5 to 4 times in a direction (width direction) perpendicular to the longitudinal direction in an atmosphere heated to a temperature of 90 to 150 ° C. .
• the draw ratio is 2.5 to 4 times in each of the longitudinal direction and the width direction, but the area ratio (longitudinal draw ratio ⁇ lateral draw ratio) needs to be 9 to 16 times, and is 10 to 12 times. More preferably.
• the area magnification is less than 9 times, formation of air bubbles and irregularities in the resulting white reflective film and film strength are insufficient, and when the area magnification exceeds 16 times, tearing tends to occur during stretching.
• the white reflective film of the present invention can be obtained by cooling to room temperature, and then, if necessary, performing corona discharge treatment or the like in order to further improve the adhesion to other materials and winding.
• the white reflective film of this invention is used suitably for an edge light type backlight.
• the edge light type backlight is incorporated in a housing having irregularities, and the white reflective film and the light guide plate of the present invention are incorporated in this order, and the white film is incorporated so that the surface layer (A) side faces the light guide plate. It is.
• a light source such as an LED is installed at the edge portion of the light guide plate.
• a diffusion plate, a prism, or the like may be installed on the front surface of the light guide plate (on the side opposite to the white reflective film).
• the white reflective film of the present invention is used for a backlight, and among others, it can be suitably used for an edge light type liquid crystal display backlight and an illumination surface light source such as a signboard or a vending machine.
• paper substitutes, ie cards, labels, stickers, home delivery slips, video printer paper, inkjet, barcode printer paper, posters, maps, dust-free paper, display boards, white boards, thermal transfer, offset printing, telephones
• Receiving sheet base materials used for various printing records such as cards and IC cards, building materials such as wallpaper, lighting equipment and indirect lighting equipment used indoors and outdoors, members mounted on automobiles, railways, aircraft, etc., circuit materials, etc. It can also be used as an electronic component.
• Measurement Method The physical property value evaluation method and effect evaluation method of the present invention are as follows.
• Tmc Temperature drop crystallization temperature
• the mixture was heated from 25 ° C. to 300 ° C. at a temperature increase rate of 20 ° C./min, held in that state for 5 minutes, and then rapidly cooled to 25 ° C. or lower. Immediately thereafter, the temperature was raised again from room temperature to 300 ° C. at a rate of temperature increase of 20 ° C./minute, held in that state for 5 minutes, and then lowered from 300 ° C. to 25 ° C. at a rate of 20 ° C./minute, Endothermic / exothermic peaks were measured in each temperature increase and decrease process, excluding the rapid cooling process. The exothermic peak temperature in the process of lowering the temperature from 300 ° C. to 25 ° C.
• Tmc temperature lowering crystallization temperature
• Tmc1 the temperature-falling crystallization temperature
• Tmc2 the temperature-falling crystallization temperature
• the size of the light emitting surface was 89 cm ⁇ 50 cm, and the diagonal length was 102.2 cm.
• the light guide plate is taken out from this backlight, the light guide plate is cut into a 5 cm square, the uneven portion of the light guide plate and the surface layer (A) of the white reflective film of the present invention are overlaid, and 500 g on the opposite side of the surface layer (A).
• the weight is placed, and 3 cm ⁇ 5 is reciprocated so as to rub the surface layer (A) of the white reflective film of the present invention. Thereafter, the surface (A) surface of the 5 cm square light guide plate that was in contact with the surface of the white reflective film of the present invention was observed with a microscope, and the following evaluation results were obtained.
• A Excellent (Luminance unevenness is not visible in both a 500 Lx illumination environment and a dark environment.)
• B Good (Luminance unevenness is visible in a dark environment of 500 Lx, but no luminance unevenness is visible in an illumination environment.)
• F Inferior (Brightness unevenness is visible both in a 500 Lx illumination environment and in a dark environment.) Said A and B were set as the pass.
• ⁇ Copolymerization is carried out by polycondensation reaction of dimethyl terephthalate as the polyester acid component with alicyclic structure and CHDM (cyclohexanedimethanol) as the diol component in the presence of 200 ppm butyltin tris (2-ethylhexanoate). Polyester was obtained.
• Examples 1 to 8 57 parts by mass of PET, 5 parts by mass of a (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 ethylene glycol 8 parts by mass of copolymerized polyethylene terephthalate (33 mol% CHDM copolymerized PET), 20 parts by mass of poly (5-methyl) norbornene, and 10 parts by weight of rutile-type titanium oxide were mixed and dried at 180 ° C. for 3 hours. After that, it was fed to Extruder B heated to 270 to 300 ° C. (B layer).
• B layer rutile-type titanium oxide
• layer (A) PET, PET-I, alicyclic structure a “TRITAN” (manufactured by Eastman Chemical Company), alicyclic structure b “EASTAR” (registered trademark) (manufactured by Eastman Chemical Company), particles Using a particle size of 0.6 ⁇ m silica for a, a particle size of 3.5 ⁇ m silica for particle b, and a sulfur burr with a particle size of 0.6 ⁇ m for particle c were mixed in the proportions shown in Table 1 and vacuum dried at 180 ° C. for 3 hours.
• 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, the film was heat-set at 200 ° C. in a tenter, uniformly cooled, cooled to room temperature, and a biaxially stretched laminated film was obtained.
• the physical properties of the light reflecting substrate are shown in Table 1. As described above, the white reflective film of the present invention was able to be stably formed, and exhibited excellent characteristics in the surface shape (heavy load spot test, light guide plate contamination, luminance unevenness reduction).
• Example 9 (Surface (A)) Amorphous cycloolefin-based resin A (manufactured by Nippon Zeon Co., Ltd., trade name “ZEONOR 1430R”, density (ASTM D792): 1.01 g / cm 3 , glass transition temperature Tg (JISK7121): 133 ° C. pellets and polypropylene resin ( A mixture of pellets of Nippon Polypro Co., Ltd., trade name “NOVATEC PPEA9” at a mass ratio of 30:70 was supplied to Extruder A by the above method.
• Example 10 to 12 57 parts by mass of PET, 5 parts by mass of a (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 ethylene glycol 8 parts by mass of copolymerized polyethylene terephthalate (33 mol% CHDM copolymerized PET), 20 parts by mass of poly (5-methyl) norbornene, and 10 parts by weight of rutile-type titanium oxide were mixed and dried at 180 ° C. for 3 hours. After that, it was fed to Extruder B heated to 270 to 300 ° C. (B layer).
• PET, PET-I, and alicyclic structure b “EASTAR” (registered trademark) (manufactured by Eastman Chemical Company) were used as the layer (A), and mixed at a ratio shown in Table 1 at 180 ° C. for 3 hours.
• the polymer was supplied to an extruder A heated to 280 ° C., and these polymers were laminated through a laminating apparatus so as to be A layer / B layer / A layer, and formed into a sheet form from a T die. Further, the unstretched film obtained by cooling and solidifying this film with a cooling drum having a surface temperature of 25 ° C.
• the film 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 was performed at 200 ° C. in a tenter, and after uniform cooling, the film was cooled to room temperature and a biaxially stretched 150 ⁇ m thick laminated film was obtained. Further, by adjusting the discharge amounts of the extruder A and the extruder B, the surface thickness was adjusted to 8 ⁇ m to 12 ⁇ m while maintaining the overall thickness of 150 ⁇ m.
• Table 1 shows the physical properties of the obtained laminated film as a light reflecting substrate.
• the white reflective film of the present invention was able to be stably formed, and exhibited excellent characteristics in the surface shape (heavy load spot test, light guide plate contamination, luminance unevenness reduction).
• Comparative Examples 1 to 6 In a composite film-forming apparatus having a main extruder and a sub-extruder, film formation was performed by changing to the composition shown in Table 2. In Comparative Examples 1 and 6, since the main protrusions were particles, the light guide plate was scratched.
• PET, PET-I, and alicyclic structure b “EASTAR” (registered trademark) (manufactured by Eastman Chemical Company) were used as the layer (A), and mixed at a ratio shown in Table 1 at 180 ° C. for 3 hours.
• the polymer was supplied to an extruder A heated to 280 ° C., and these polymers were laminated through a laminating apparatus so as to be A layer / B layer / A layer, and formed into a sheet form from a T die. Further, the unstretched film obtained by cooling and solidifying this film with a cooling drum having a surface temperature of 25 ° C.
• Table 2 shows the physical properties of the obtained laminated film as a light reflecting substrate. SRa was small and uneven brightness occurred.
• the white reflective film of the present invention is used for a backlight, and among others, it can be suitably used for an edge light type liquid crystal display backlight, and an illumination surface light source such as a signboard or a vending machine. In addition, it can be suitably used as a reflection plate constituting various surface light sources, a sealing film for solar cell modules that require reflection characteristics, and a back sheet.
• paper substitutes ie cards, labels, stickers, home delivery slips, video printer paper, inkjet, barcode printer paper, posters, maps, dust-free paper, display boards, white boards, thermal transfer, offset printing, telephones
• Receiving sheet base materials used for various printing records such as cards and IC cards, building materials such as wallpaper, lighting equipment and indirect lighting equipment used indoors and outdoors, members mounted on automobiles, railways, aircraft, etc., circuit materials, etc. It can also be used as an electronic component.

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• 2016
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