CN101600977B - Surface light-diffusing polyester film - Google Patents
Surface light-diffusing polyester film Download PDFInfo
- Publication number
- CN101600977B CN101600977B CN2007800501338A CN200780050133A CN101600977B CN 101600977 B CN101600977 B CN 101600977B CN 2007800501338 A CN2007800501338 A CN 2007800501338A CN 200780050133 A CN200780050133 A CN 200780050133A CN 101600977 B CN101600977 B CN 101600977B
- Authority
- CN
- China
- Prior art keywords
- film
- light
- polyester
- diffusing
- resin
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired - Fee Related
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- 229920006267 polyester film Polymers 0.000 title claims abstract description 82
- 229920000728 polyester Polymers 0.000 claims abstract description 117
- 239000000203 mixture Substances 0.000 claims abstract description 89
- 239000010410 layer Substances 0.000 claims description 144
- 238000009792 diffusion process Methods 0.000 claims description 122
- 229920005989 resin Polymers 0.000 claims description 85
- 239000011347 resin Substances 0.000 claims description 85
- 229920001577 copolymer Polymers 0.000 claims description 64
- 239000002671 adjuvant Substances 0.000 claims description 61
- 230000035515 penetration Effects 0.000 claims description 56
- -1 acryl Chemical group 0.000 claims description 34
- 239000011247 coating layer Substances 0.000 claims description 27
- 229920001225 polyester resin Polymers 0.000 claims description 17
- 239000004645 polyester resin Substances 0.000 claims description 15
- 229920002635 polyurethane Polymers 0.000 claims description 8
- 239000004814 polyurethane Substances 0.000 claims description 8
- 230000000536 complexating effect Effects 0.000 claims description 5
- 230000008859 change Effects 0.000 abstract description 10
- 238000002844 melting Methods 0.000 abstract description 10
- 230000008018 melting Effects 0.000 abstract description 10
- 238000007334 copolymerization reaction Methods 0.000 abstract description 7
- 239000000654 additive Substances 0.000 abstract description 2
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- 230000000996 additive effect Effects 0.000 abstract 1
- 239000002245 particle Substances 0.000 description 88
- 238000000034 method Methods 0.000 description 82
- 239000000463 material Substances 0.000 description 37
- 229920000642 polymer Polymers 0.000 description 33
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 25
- 238000000576 coating method Methods 0.000 description 23
- 239000011248 coating agent Substances 0.000 description 21
- 239000002994 raw material Substances 0.000 description 21
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- 238000004519 manufacturing process Methods 0.000 description 18
- 230000003287 optical effect Effects 0.000 description 17
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- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 15
- 238000001816 cooling Methods 0.000 description 15
- 238000013459 approach Methods 0.000 description 13
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- 239000006185 dispersion Substances 0.000 description 12
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 11
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- 125000003118 aryl group Chemical group 0.000 description 9
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 238000011156 evaluation Methods 0.000 description 6
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- QQVIHTHCMHWDBS-UHFFFAOYSA-N isophthalic acid Chemical compound OC(=O)C1=CC=CC(C(O)=O)=C1 QQVIHTHCMHWDBS-UHFFFAOYSA-N 0.000 description 6
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- SLCVBVWXLSEKPL-UHFFFAOYSA-N neopentyl glycol Chemical compound OCC(C)(C)CO SLCVBVWXLSEKPL-UHFFFAOYSA-N 0.000 description 5
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- 238000004458 analytical method Methods 0.000 description 4
- ADCOVFLJGNWWNZ-UHFFFAOYSA-N antimony trioxide Chemical compound O=[Sb]O[Sb]=O ADCOVFLJGNWWNZ-UHFFFAOYSA-N 0.000 description 4
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- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 4
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- 241001597008 Nomeidae Species 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 3
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- XNGIFLGASWRNHJ-UHFFFAOYSA-N phthalic acid Chemical compound OC(=O)C1=CC=CC=C1C(O)=O XNGIFLGASWRNHJ-UHFFFAOYSA-N 0.000 description 3
- 239000004417 polycarbonate Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000004879 turbidimetry Methods 0.000 description 3
- UXFQFBNBSPQBJW-UHFFFAOYSA-N 2-amino-2-methylpropane-1,3-diol Chemical compound OCC(N)(C)CO UXFQFBNBSPQBJW-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 239000004721 Polyphenylene oxide Substances 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- YIMQCDZDWXUDCA-UHFFFAOYSA-N [4-(hydroxymethyl)cyclohexyl]methanol Chemical compound OCC1CCC(CO)CC1 YIMQCDZDWXUDCA-UHFFFAOYSA-N 0.000 description 2
- 150000001399 aluminium compounds Chemical class 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- QMKYBPDZANOJGF-UHFFFAOYSA-N benzene-1,3,5-tricarboxylic acid Chemical compound OC(=O)C1=CC(C(O)=O)=CC(C(O)=O)=C1 QMKYBPDZANOJGF-UHFFFAOYSA-N 0.000 description 2
- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 239000010627 cedar oil Substances 0.000 description 2
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- FUZZWVXGSFPDMH-UHFFFAOYSA-N hexanoic acid Chemical compound CCCCCC(O)=O FUZZWVXGSFPDMH-UHFFFAOYSA-N 0.000 description 2
- 238000000265 homogenisation Methods 0.000 description 2
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- 235000012204 lemonade/lime carbonate Nutrition 0.000 description 2
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 description 2
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- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 2
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- 229910052573 porcelain Inorganic materials 0.000 description 2
- CXMXRPHRNRROMY-UHFFFAOYSA-N sebacic acid Chemical compound OC(=O)CCCCCCCCC(O)=O CXMXRPHRNRROMY-UHFFFAOYSA-N 0.000 description 2
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- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- 150000002697 manganese compounds Chemical class 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000113 methacrylic resin Substances 0.000 description 1
- OJURWUUOVGOHJZ-UHFFFAOYSA-N methyl 2-[(2-acetyloxyphenyl)methyl-[2-[(2-acetyloxyphenyl)methyl-(2-methoxy-2-oxoethyl)amino]ethyl]amino]acetate Chemical compound C=1C=CC=C(OC(C)=O)C=1CN(CC(=O)OC)CCN(CC(=O)OC)CC1=CC=CC=C1OC(C)=O OJURWUUOVGOHJZ-UHFFFAOYSA-N 0.000 description 1
- ADFPJHOAARPYLP-UHFFFAOYSA-N methyl 2-methylprop-2-enoate;styrene Chemical compound COC(=O)C(C)=C.C=CC1=CC=CC=C1 ADFPJHOAARPYLP-UHFFFAOYSA-N 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- KYTZHLUVELPASH-UHFFFAOYSA-N naphthalene-1,2-dicarboxylic acid Chemical compound C1=CC=CC2=C(C(O)=O)C(C(=O)O)=CC=C21 KYTZHLUVELPASH-UHFFFAOYSA-N 0.000 description 1
- RXOHFPCZGPKIRD-UHFFFAOYSA-N naphthalene-2,6-dicarboxylic acid Chemical compound C1=C(C(O)=O)C=CC2=CC(C(=O)O)=CC=C21 RXOHFPCZGPKIRD-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 239000012766 organic filler Substances 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- UWJJYHHHVWZFEP-UHFFFAOYSA-N pentane-1,1-diol Chemical compound CCCCC(O)O UWJJYHHHVWZFEP-UHFFFAOYSA-N 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229920001707 polybutylene terephthalate Polymers 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 229920006149 polyester-amide block copolymer Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920000193 polymethacrylate Polymers 0.000 description 1
- 239000011116 polymethylpentene Substances 0.000 description 1
- 229920000306 polymethylpentene Polymers 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 229920005672 polyolefin resin Polymers 0.000 description 1
- 229920006380 polyphenylene oxide Polymers 0.000 description 1
- 229920000069 polyphenylene sulfide Polymers 0.000 description 1
- 229920002215 polytrimethylene terephthalate Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- SCUZVMOVTVSBLE-UHFFFAOYSA-N prop-2-enenitrile;styrene Chemical compound C=CC#N.C=CC1=CC=CC=C1 SCUZVMOVTVSBLE-UHFFFAOYSA-N 0.000 description 1
- DNIAPMSPPWPWGF-UHFFFAOYSA-N propylene glycol Substances CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000001632 sodium acetate Substances 0.000 description 1
- 235000017281 sodium acetate Nutrition 0.000 description 1
- XHFLOLLMZOTPSM-UHFFFAOYSA-M sodium;hydrogen carbonate;hydrate Chemical compound [OH-].[Na+].OC(O)=O XHFLOLLMZOTPSM-UHFFFAOYSA-M 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000002345 surface coating layer Substances 0.000 description 1
- ISIJQEHRDSCQIU-UHFFFAOYSA-N tert-butyl 2,7-diazaspiro[4.5]decane-7-carboxylate Chemical compound C1N(C(=O)OC(C)(C)C)CCCC11CNCC1 ISIJQEHRDSCQIU-UHFFFAOYSA-N 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 239000003017 thermal stabilizer Substances 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
- 238000004876 x-ray fluorescence Methods 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
- 239000004246 zinc acetate Substances 0.000 description 1
Classifications
-
- 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
- G02B5/021—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
- G02B5/0226—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures having particles on the surface
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
- B29C48/07—Flat, e.g. panels
- B29C48/08—Flat, e.g. panels flexible, e.g. films
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
- B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
- B29C55/10—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial
- B29C55/12—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/02—Diffusing elements; Afocal elements
- G02B5/0268—Diffusing elements; Afocal elements characterized by the fabrication or manufacturing method
-
- 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
- G02B5/0278—Diffusing elements; Afocal elements characterized by the use used in transmission
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
Abstract
Disclosed is a light-diffusing polyester film composed of a biaxially oriented polyester film, which is characterized in that (1) the film has a supporting layer composed of a crystalline homopolyester or a crystalline polyester containing a copolymerization component, and a light-diffusing layer arranged on at least one side of the supporting layer by co-extrusion and composed of a blended composition containing 50-99 parts by mass of a crystalline polyester containing a copolymerization component having a melting point of 235-255 DEG C and 1-50 parts by mass of an additive incompatible with the polyester. This light-diffusing polyester film is further characterized in that (2) the film has a plane orientation coefficient Delta P of 0.08-0.16; (3) the film has a surface haze of not less than 15%; (4) the film has an internal haze less than the surface haze; and (5) the film has a dimensional change rate at 150 DEG C of not more than 3% and a tensile strength of not less than 100 MPa.
Description
Technical field
The present invention relates to used light diffusing film in a kind of backlight liquid crystal display lamp unit, the lighting device etc. at big picture and high brightness.More particularly, relate to a kind of take into account light diffusing and light penetration and be accompanied by the generation of curling of temperature variation little, surface light-diffusing polyester film.
Background technology
In recent years, the technical progress of LCD is remarkable unusually, and the display device that is used as PC or televisor, portable phone etc. is extensive use of.Owing to do not have lighting function in independent liquid crystal display cells, so these LCD are provided with backlight unit at its back side, thereby can show.
Variety of way is arranged in backlight unit, yet be divided into two kinds haply.In general maximum modes is the mode that is known as directly-below type, is the mode that light source is in the inboard of irradiation face.In this mode and since light sources such as a plurality of cold cathode ray tubes can be disposed at the irradiation face under, therefore have and can obtain high brightness and the little feature of light loss.Thus, to be used for large-scale liquid crystal TV etc. large-scale and need in the LCD of high brightness more.
Another mode is the mode that is known as edge light type, it is following mode, promptly, light source is disposed at outside the irradiation face, driving fit fluorescent light approximate wire luminophors such as (mostly being cold cathode discharge tube) on one side that is disposed at the light guide plate of being made by transparent acrylic resin board etc. on the irradiation face or two sides is provided with the lampshade of being made by reflecting body and imports light in the light guide plate.This mode has little, the feature that can small-sized slimming of power consumption.Thus, miniscope that is widely used in subnotebook PC etc. etc. needs in the purposes of slimming, lighting especially.
To the desired function of the light guide plate of edge light type backlight unit be: the function that the light that will inject from the end forwards transmits, with the light that transmitted function to the output of liquid crystal display cells side.The former function is to determine according to used material and boundary reflection characteristic.In addition, the latter's function is according to the shape decision on the light guide plate surface of avoiding total reflection condition.As the formation method of the shape on this light guide plate surface, known have pair method of the diffusion material of the additional white in light guide plate surface and to the method for the Fresnel shape of additional biconvex lens in light guide plate surface or prism.But the light that penetrates from the light guide plate with these surface configurations can demonstrate the uneven distribution that is caused by its shape.So, in order to obtain high quality images, carried out following effort, that is, the light diffusing film is set on light guide plate, light diffusion, the scattering that will penetrate from light guide plate make the brightness of irradiation face even.
In these backlight units,, use sometimes and be known as the sheet with light-focusing function of prismatic lens or lens, thereby the light that will see through the light diffusing film is pooled to frontal as much as possible in order further to improve its front face brightness.Be arranged with small concavo-convex such as a plurality of prism-like or netted, pyramid shape on the surface of this sheet, will have seen through the emergent light refraction of light diffusing film and compile, improve the brightness of irradiation face to the front.This kind prismatic lens is that the face side at above-mentioned light diffusing film sets a slice or sets two and use overlappingly.
In addition, for the defective that makes the brightness disproportionation that produces because of setting of above-mentioned prismatic lens or prismatic lens unshowy (improving disguised), the face side at prismatic lens also sets the light diffusing film sometimes.
As light diffusing film used in the aforesaid backlight unit, the light diffusion layer that constitutes by the transparent resin that contains particulate in the surface-coated of biaxial stretching polyester film and film (for example with reference to patent documentation 1,2) become main flow.
Patent documentation 1: Japanese kokai publication hei 6-59108 communique
Patent documentation 2: No. 3698978 instructions of Jap.P.
But, in this method, light diffusion layer is set owing to need apply in the one side utilization of base material film, therefore can be because the difference of the linear expansion coefficient of light diffusion layer and base material film, and make the light diffusing film become the structure of thermometal shape, thereby the problem of curling that is caused by heating that is easy to generate is arranged.This problem is particularly large-scale and need become important problem gradually in the LCD high brightness, that adopt directly downward type backlight in recent years large-scale liquid crystal TV etc.This be because, the light diffusing film is large tracts of landization, then curling just becomes obvious more, in addition, display is high brightnessization, the then power consumption of light source, is that the thermal value of backlight just becomes big more.
In order to address this problem, need to realize bimetallic elimination.In general, adopt following countermeasure, that is,, form hard coat (non-light diffusing layer) to the thickness of tens of μ m to count μ m on the surface of the light diffusion layer of base material film, at folder every the two sides of light diffusion layer balanced line differential expansion stress.
But the thickness of above-mentioned hard coat is unwanted originally, becomes the increase that causes unnecessary thickness and the cause of increased of manufacturing cost for the light diffusing film.In addition, for the countermeasure of the polar expansion stress equilibrium that makes the table back side, the limit is arranged also, in formerly described big picture, the high brightness indicator, can only obtain not enough effect of sufficient.
In addition, in recent years, be purpose with the reduction of backlight unit number of parts or simplification, the cost degradation of manufacturing process, also carried out a lot with light diffusing film and other the incorporate research of optical functional film.
For example, prismatic lens (with reference to patent documentation 3) with following feature was disclosed, that is,, contain the light diffusion layer of a plurality of light transmission pearls in second side formation of above-mentioned base material at first side formation prism row of tabular light transmission base material with first and second these two first type surfaces.
In addition, following liquid crystal indicator lens (with reference to patent documentation 4) was also disclosed, that is, the light diffusion layer that will be made of the thermoplastic resin that has mixed light diffusing agent, the cambial two-layer laminate at least of prism shape that formed prism shape on the surface of the thermoplastic resin of unmixed light diffusing agent form.
In addition, the prismatic lens light scattering biaxial stretching polyester film (with reference to patent documentation 5) that utilizes light scattering agent that adds film inside to and the space that produces around it to give light diffusing was also disclosed.
Patent documentation 3: Japanese kokai publication hei 9-281310 communique
Patent documentation 4: No. 3732253 instructions of Jap.P.
Patent documentation 5: TOHKEMY 2005-181648 communique
But, in the disclosed method,, therefore form so-called antidiffusion state in the patent documentation 3 owing to have the plane of incidence side that the light transmission pearl of lensing is located at light, have the problem that front face brightness reduces widely.Thus, utilize this method can't give enough brightness and light diffusing.
On the other hand, in the disclosed method, owing to utilize the light-scattering material of base material inside to give light diffusing, therefore the incident light of a part produces backscattering in patent documentation 4 or the patent documentation 5, thus the problem that has light penetration to reduce.
In addition, in recent years, excessively much want to make the biaxial stretching polyester film that has excellent thermotolerance, physical strength, thickness evenness concurrently itself to have the research of light diffusing.Make the polyester film that is made of single material in essence have integrated also the opened up road of the way of light diffusing for curling problem solution, diffusion sheet and prismatic lens function of above-mentioned heating, its industrialness is worth very big.
But, the trial that makes the biaxial stretching polyester film itself have light diffusing that is proposed up to now all can damage original certain speciality that has of biaxial stretching polyester film (thermotolerance, physical strength etc.), or the light diffusing film of infringement light penetration or light diffusing and so on the characteristic that should possess, do not reach practicability as yet.
For example, though disclosed film is pushed the original speciality that has of biaxial stretching polyester film that measuring tool has excellent thermotolerance, physical strength, excellent thickness evenness and so in the above-mentioned patent documentation 5, yet, therefore have the low problem of light penetration owing to be to utilize the bubble of the inside that is present in layer to give light diffusing.The bubble (space) that produces in the two-way stretch operation of film has and the parallel flat form in film surface.Thus, be used for as the light diffusing film under the situation of backlight unit, the major part generation backscattering of the light that from the irradiation face, penetrates, light penetration suffers damage.In fact, the total light penetration shown in the embodiment is the highest also nothing but 85.3%.
In addition, as the formation vibrin of the light diffusion layer that contains particulate, disclosed by used polyethylene terephthalate (PET) go up copolymerization 25mol% the isophthalic acid composition non-crystalline polyester interior lights diffusivity film and be laminated in its lamination light diffusing film (with reference to patent documentation 6) of constituting of PET film of one side at least.
Patent documentation 6: TOHKEMY 2001-272508 communique
In the said method, because the elimination in space is kept a close eye on, so light penetration improves.But it also is identical giving aspect the light diffusing in the light scattering that utilizes film inside in this method, still can't avoid being accompanied by the reduction of the light penetration that the backscattering of incident light produces.
In addition, in the film of patent documentation 6, the formation resin of substrate layer (PET homopolymer) is obviously different with the crystallinity of the formation resin (non-crystalline polyester) of light diffusion layer.Consequently, the biaxial stretching film of gained itself becomes the structure of thermometal shape, and biaxial stretching film itself curls because of heating produces easily.Thus, produce curling because of the thermal treatment of back in the manufacturing procedure, the environment for use (temperature) of LCD sometimes.
In addition, following film was disclosed, promptly, with fusing point below 210 ℃ or non-crystalline polyester as constituting resin, with the light diffusing layer that in this formation resin, cooperated the light diffusing adjuvant that constitutes by immiscible particle or thermoplastic resin as the middle layer, the stacked crystalline polyester resin layer (with reference to patent documentation 7～13) on its two sides.
Patent documentation 7: TOHKEMY 2001-324606 communique
Patent documentation 8: TOHKEMY 2002-162508 communique
Patent documentation 9: TOHKEMY 2002-182013 communique
Patent documentation 10: TOHKEMY 2002-196113 communique
Patent documentation 11: TOHKEMY 2002-372606 communique
Patent documentation 12: TOHKEMY 2004-219438 communique
Patent documentation 13: TOHKEMY 2004-354558 communique
In these methods,, therefore, improvement is to a certain degree arranged for the generation of curling that is configured to by unsymmetrical knot because the structure of film is a table back side symmetry.But, between light diffusing middle layer and superficial layer, have very big not change the problem that the planarity when existing temperature variation inherently worsens significantly because of the bed thickness change of a little or the rerum natura change at the table back side etc. aspect crystalline different.
In addition, in these methods, because the major part of film by amorphism or obviously lack crystalline polyester and constitute, therefore can't obtain thermotolerance, physical strength and the thickness evenness of the original excellence of biaxial stretching film.
The two-way stretch polyethylene terephthalate film (with reference to patent documentation 14) of the particle of the spherical or lens-shaped that has cooperated specified particle diameter was disclosed in addition.
Patent documentation 14: TOHKEMY 2002-37898 communique
In the patent documentation 14, disclose following film in an embodiment, that is, use the raw material of polyethylene terephthalate, have 88% total light penetration and 68% diffusion transmitance simultaneously as polyester.In addition, disclose the film of diffusion transmitance with total light penetration of 85% and 63%.But, basic characteristics such as the thermotolerance of unexposed any these films, physical strength, thickness and precision are not seen the possibility of acquisition as thermotolerance, physical strength and the high thickness and precision of the original feature of two-way stretch polyethylene terephthalate film fully yet.
This be because, although these films are respectively to stretch 3 times by the unstretching film with thick 200 μ m along longitudinal and transverse two directions, just with 9.0 times of films that stretch and obtain of area multiplying power, yet its thickness is 50 μ m, only 4.0 times of the area stretching ratios of the reality of calculating according to the thickness ratio before and after stretching.That is to say and can think that the stretching ratio that produces when being subjected to the shrinkage in width that produces or cross directional stretch when longitudinal stretching distributes and the influences such as change in size during thermal treatment, the setting multiplying power of stretcher deviates from significantly with actual stretching ratio.In addition, if actual area stretching ratio is the stretching about 4 times, even then can obtain excellent light penetration, in any case also can not realize thermotolerance, physical strength and high thickness and precision as the original feature of biaxial stretching film.
As mentioned above, the film base material of thermometal shape is accompanied by maximization, the high powerization of LCD with backlight unit, be easy to generate curling problem and become more and more obvious, for addressing the above problem, wish not to use actual stretched film (patent documentation 1,2) itself by the method for coated off-line.But, biaxial stretching film itself is had in the method for light diffusing, can't avoid the generation in the space of causing by the light diffusing particle, thereby the problem (patent documentation 3,4,5) that has total light penetration to reduce.As the method for the generation of avoiding the space, utilized in the past the resin proterties of implementation or the change of stretching condition always can not solve curling problem (patent documentation 6), the problem (patent documentation 7-14) of the mechanical strength reduction of film is perhaps arranged.That is, because therefore the mechanical characteristic of biaxial stretching film and the relation that optical characteristics belongs to antinomy can't obtain the film that any characteristic all satisfies.Thus, aspect overall quality, still not as good as method in the past, so said method does not reach practicability as yet to processing additional optical diffusion layer after the utilization of transparent base film.
Summary of the invention
The objective of the invention is to, a kind of surface light-diffusing polyester film is provided, it has thermotolerance, physical strength and the thickness and precision etc. of the original excellence of biaxial stretching polyester film, and take into account total light penetration and light diffusing, also suppressed to derive from the curling generation of heating of bimetal structure in addition.
The surface light-diffusing polyester film of the present invention that can solve the above problems is formed by following constituting.
That is, the formation of the technical scheme 1 described invention among the present invention is a kind of light diffusing polyester film of being made by the double orientation polyester film, it is characterized in that, satisfies following important document (1)～(5).
(1) have supporting course and through coetrusion be laminated in described supporting course at least the one side light diffusion layer, described supporting course comprises the equal polyester of crystallinity or contains the crystallinity polyester of copolymer composition, described light diffusion layer comprise contain fusing point be 235～255 ℃ copolymer composition crystallinity polyester 50～99 mass parts and be the complexing compositions of adjuvant 1～50 mass parts of immiscible property to described polyester.
(2) the planar orientation coefficient delta P with the film of following formula definition is 0.08～0.16
ΔP＝(nx+ny)/2-nz
Here, nx, ny, nz represent the refractive index of length direction, the refractive index of Width, the refractive index of thickness direction respectively.
(3) surface haze is more than 15%.
(4) inner turbidity is less than surface haze.
Size changing rate in the time of (5) 150 ℃ laterally all is below 3% vertically reaching, and tensile strength laterally all is more than the 100MPa vertically reaching.
Being formed in the technical scheme 1 described invention of technical scheme 2 described inventions has following feature, that is, total light penetration is more than 86%, and (Japanese: the く width of cloth) 2mm's is below 40% as vividness to comb width.
Being formed in the technical scheme 1 described invention of technical scheme 3 described inventions has following feature, promptly, on the surface of above-mentioned light diffusion layer, have before the stretch orientation of film finishes setting with more than copolymer polyester resin, polyurethane series resin or acryl resin at least a as the coating layer of major component.
Being formed in the technical scheme 1 described invention of technical scheme 4 described inventions has following feature, promptly, on the light diffusion layer side of above-mentioned light diffusing polyester film and supporting course side two sides' face, has at least a above coating layer as major component with copolymer polyester resin, polyurethane series resin or acryl resin.
The formation of technical scheme 5 described inventions is characterised in that, technical scheme 1 described surface light-diffusing polyester film is the prismatic lens purposes, on the face of an opposite side, has at least a above coating layer as major component with copolymer polyester resin, polyurethane series resin or acryl resin with light diffusion layer.
Surface light-diffusing polyester film of the present invention is because supporting course and light diffusion layer all are by constituting with the sandwich construction of crystallinity polyester as main material, therefore can suppress to derive from the curling generation of heating of bimetal structure, and thermotolerance, physical strength and thickness and precision with the original excellence of biaxial stretching polyester film.
In addition, surface light-diffusing polyester film of the present invention will be owing to will contain the main material of the crystallinity polyester of copolymer composition as light diffusion layer, Zheng Ti planar orientation coefficient is controlled in the particular range in addition, therefore do not have the situation that substantially produces the space on every side of the adjuvant of the immiscible property in adding light diffusion layer to, and have concaveconvex structure on the light diffusion layer surface.Will have excellent surface light-diffusing and high light penetration thus concurrently.
Embodiment
The invention provides a kind of surface light-diffusing polyester film, it has suppressed the generation of curling that caused by heating, and the mechanical characteristic with the original excellence of biaxial stretching polyester film, has taken into account total light penetration and light diffusing in addition.In order to realize taking into account of above-mentioned characteristic, the present application people etc. are conceived to the relation of the planar orientation coefficient of film, inner turbidity and surface haze especially, further investigate.Consequently, discoveries such as the present application people, the described approach in following by adopting (1)～(7) just can be taken into account the characteristic that this belongs to antinomy, thereby form the present invention.So, at first these features of reaching approach are described.And can think, for taking into account the above-mentioned characteristic that belongs to antinomy, specific certain in the approach of just following (1)～(7) can not be contributed effectively, and is used in combination by the approach with (1)～(7), just can take into account the above-mentioned characteristic that belongs to antinomy first.
(1) control of the melting point resin of light diffusion layer
(2) control of fusing point difference
(3) control of the stacked formation of light diffusion layer
(4) control of the thickness of light diffusion layer
(5) light diffusion layer constitutes the control of the intrinsic viscosity of resin
(6) control of the melt viscosity difference of substrate polymer and immiscible resin
(7) control of draft temperature and temperature condition of heat treatment
(1) control of the melting point resin of light diffusion layer (B)
Surface light-diffusing polyester film of the present invention has the supporting course (A) of the crystallinity polyester that comprises the equal polyester of crystallinity or contain copolymer composition, and has the light diffusion layer (B) of the complexing compositions of the adjuvant that comprises the crystallinity polyester that contains copolymer composition and this immiscible property.Here, the equal polyester of crystallinity polyester/crystallinity is meant the polyester/equal polyester with fusing point.Endotherm peak temperature when so-called fusing point is fusing detected when once the heating up of so-called differential scanning calorimetric determination (DSC).Under the situation of using differential scanning type calorimeter measurement,, just be contained in the equal polyester of crystallinity polyester/crystallinity so long as can observe the clearly polyester of crystal melting thermal spike/equal polyester as fusing point.
If consider from the thermotolerance physical strength of film, the aspect of thickness and precision, then the fusing point of resin is high more good more.But, under the high situation of the fusing point of resin,,, just being easy to produce space (cavity) when stretching if therefore immiscible particle is arranged in resin because the drawing stress that produces together will increase, total light penetration reduces.The condition effect though the easness of the generation in space is also stretched as described later, however with the planar orientation coefficient of the film of made very strong relevance is arranged.The state of orientation of the macromolecular chain that forms in the film after the planar orientation coefficient is represented to stretch, this state of orientation is high more, and then mechanical strength is just strong more, and the space that produces in film is also just many more.Thus, reduce the planar orientation degree of film, suppress the generation in space, the fusing point that preferably will constitute the resin of light diffusion layer (B) is controlled within the specific limits.The lower limit of the fusing point of the crystallinity polyester that contains copolymer composition of formation light diffusion layer (B) is preferably 235 ℃, more preferably 240 ℃.If fusing point is 235 ℃, then can obtain to bring into play the orientation coefficient of the degree of desirable thermotolerance, physical strength and thickness and precision.In addition, the upper limit of the fusing point of the crystallinity polyester that contains copolymer composition of formation light diffusion layer (B) is preferably 255 ℃.If fusing point is below 255 ℃, then can suppress the generation in the space in the light diffusion layer (B), therefore preferred.
(2) control of fusing point difference
Surface light-diffusing polyester film of the present invention has the supporting course (A) of the crystallinity polyester that comprises the equal polyester of crystallinity or contain copolymer composition.In order to obtain thermotolerance, physical strength, the thickness and precision of regulation as film, be good with the high person of fusing point of the equal polyester of crystallinity polyester/crystallinity that constitutes supporting course (A).But, under the big situation of the fusing point that constitutes supporting course (A) and this two-layer resin of light diffusion layer (B), be easy to generate by curling that bimetal structure causes.Thus, the equal polyester of crystallinity polyester/crystallinity that constitutes supporting course (A) is preferably in 25 ℃ with the fusing point difference of the crystallinity polyester that constitutes light diffusion layer (B), more preferably in 20 ℃, more preferably in 10 ℃, more preferably in 8 ℃, be preferably especially in 5 ℃ again.If the fusing point difference is in 25 ℃, then the generation of curling that is configured to by bimetallic junction can be suppressed in the usage range.And, being preferably above-mentioned scope owing to constitute the fusing point of the resin of light diffusion layer (B), the upper limit of fusing point that therefore constitutes the equal polyester of crystallinity polyester/crystallinity of supporting course (A) is preferably 270 ℃.
The fusing point that constitutes the crystallinity polyester of supporting course (A) and light diffusion layer (B) can be copolymerized into the control of assigning to by importing.Particularly in the present invention, preferably in the crystallinity polyester that constitutes light diffusion layer (B), import the copolymer composition of ormal weight.By copolymer composition is imported in the polyester, just can control the planar orientation coefficient of biaxial stretching film, thereby can take into account light penetration and light diffusing to heavens.But if import copolymer composition too much, then the fusing point of polyester will reduce, and can't obtain the characteristic of the original excellence of biaxial stretching polyester film, therefore need be noted.Perhaps with respect to dextrose components generally speaking the import volume of copolymer composition, is preferably 3 moles more than the % with respect to aromatic dicarboxylic acid composition integral body, more preferably 5 moles more than the %, more preferably 7 moles more than the %, is preferably 8 moles especially more than the %.Under the situation of content greater than 3 moles of % of copolymer composition, can suppress the generation in space, take into account light penetration and light diffusing easily to heavens, therefore preferred.On the other hand, as the upper limit of the import volume of copolymer composition, be 20 moles below the % preferably with respect to mentioned component, more preferably 18 moles below the %, be preferably 15 moles especially below the %.Content at copolymer composition is under 20 moles of situations below the %, owing to can obtain the fusing point that the mechanical characteristic of biaxial stretching polyester film is in the degree of usage range, and therefore preferred.And, will narrate in the back for the composition of the copolymer composition that can be used for the present invention.
(3) control of the stacked formation of light diffusion layer (B)
Surface light-diffusing polyester film of the present invention is made of very important following sandwich construction, promptly, even numbers crystallinity polyester or, in the one side at least of the supporting course (A) that comprises the crystallinity polyester that contains copolymer composition, utilize that coetrusion is stacked to be comprised the crystallinity polyester that contains above-mentioned copolymer composition and be the light diffusion layer (B) of complexing compositions of the adjuvant of immiscible property to this polyester.
The scattering that the diffusion of the light in the light diffusion layer (B) can divide for scattering that the surface structure by film causes, be caused by the inner structure of film.Aforementioned scattering can be used as surface haze evaluation, and the aftermentioned scattering can be used as inner turbidity and estimates.Therefore the scattering of light that is caused by inner structures such as spaces can't obtain high total light penetration owing to be accompanied by backscattering.Yet do not have the situation that significantly reduces total light penetration by the scattering of light that surface structure causes, can obtain high light diffusing.But,, just be difficult to avoid be accompanied by the generation of curling of the structure of thermometal shape in order in light diffusion layer (B), to realize effective surface haze.Among the present invention,, just can be provided in the high film of surface haze when suppressing to heat the generation of curling by the approach of taking to be announced in (1) to (7).Promptly, surface light-diffusing polyester film of the present invention is by adopting above-mentioned sandwich construction, not only can utilize the concaveconvex structure on light diffusion layer (B) surface that causes by immiscible property adjuvant to give light diffusing, and can suppress the light scattering (inner turbidity) of the inside of film and realize high total light penetration.Like this, just can realize taking into account of high photopermeability and light diffusing.
Under the situation that surface light-diffusing polyester film of the present invention is used as prismatic lens, can by will the one side of supporting course (A) stacked the film of light diffusion layer (B) as base material, to the additional prism structure of face of the opposite side of light diffusion layer (B) and use suitably.It can be 2 layers of formation as mentioned above also that the layer of surface light-diffusing polyester film of the present invention constitutes, as long as can obtain effect of the present invention, the multilayer that also can be made as required more than 3 layers constitutes.If smooth (the not having concaveconvex structure) film of overlapped surfaces then can produce Newton ring on smooth transparent component, have the situation that observability reduces.Thus, under the situation that the film with invention uses as light diffusing sheet individually, in order to prevent, preferably at the stacked light diffusion layer in the two sides of supporting course (A) (B) by the generation that overlaps the Newton ring that causes with light guide plate or prismatic lens.And, for the composition of the immiscible adjuvant that can be used for the present invention, will narrate in the back.
(4) control of the thickness of light diffusion layer (B)
Surface light-diffusing polyester film of the present invention has supporting course (A) and light diffusion layer (B), yet in order to obtain surface light-diffusing polyester film of the present invention, the thickness of light diffusion layer (B) is very important.The surface haze of light diffusion layer (B) has the big more orientation that will become high more of concave-convex surface.Thus, the particle diameter of the adjuvant of light diffusion layer (B) is the bigger the better.In order to obtain effective particle diameter for surface haze, the lower limit of the thickness of light diffusion layer (B) is preferably more than the 3 μ m, and more preferably 4 μ m are preferably 5 μ m especially.
On the other hand, if the thickness of light diffusion layer (B) largely more than the particle diameter of immiscible adjuvant, then is difficult to form effectively surface relief structure.Thus, if strengthen the thickness of light diffusion layer (B), then concave-convex surface forms and will reduce, and surface haze reduces.In addition, along with the thickening of light diffusion layer (B), the inside turbidity that is caused by the inner structure of light diffusion layer (B) will uprise, and total light penetration reduces.In order to realize taking into account of high total light penetration and light diffusing, preferably in the scope of THICKNESS CONTROL below regulation with light diffusion layer (B).Thus, the upper limit of the thickness of light diffusion layer (B) is preferably 50 μ m, 30 μ m more preferably, and more preferably 25 μ m are preferably 20 μ m especially.
In addition, if light diffusion layer (B) uprises with respect to the ratio of film integral thickness (A+B), then be easy to take place the generation of curling that is configured to by bimetallic junction.In addition, increase owing to compare the ratio of the relatively low light diffusion layer of fusing point (B) with supporting course (A), therefore generally speaking be easy to generate uneven thickness as film, surface smoothing suffers damage.In addition, because light diffusion layer (B) contains a lot of copolymer compositions, therefore as generally speaking orientation coefficient reduction of film, mechanical characteristic reduces.On the other hand, if light diffusion layer (B) is little with respect to the ratio of film integral thickness, the then surface that the adjuvant in the light diffusion layer (B) will oriented film situation of oozing out or situation about coming off.Thus, preferably light diffusion layer (B) is controlled to be the scope of regulation with respect to the ratio of film integral thickness, is preferably 2～50% scope.Light diffusion layer (B) is preferably 2% with respect to the lower limit of the ratio of film integral thickness (A+B), and more preferably 3%, be preferably 4% especially.On the other hand, light diffusion layer (B) is preferably 50% with respect to the upper limit of the ratio of film integral thickness, and more preferably 35%, be preferably 20% especially.
(5) light diffusion layer (B) constitutes the control of the intrinsic viscosity of resin
The invention is characterized in, utilize coetrusion to give light diffusion layer (B).Because surface light-diffusing polyester film of the present invention is to be purpose with the optical applications, therefore the optical defect that is caused by foreign matter is few more good more, is utilizing coetrusion to supply with under the situation of resin, is preferably on the molten thread (melt line) foreign matter to be set and to remove filtrator.In order to make resin remove filtrator, need certain extrusion pressure, yet under the low situation of the intrinsic viscosity of resin,, therefore be difficult to carry out stable system film because the ejection stability during the extruding of molten resin reduces by foreign matter.In addition, under the low situation of the intrinsic viscosity of resin, the planar orientation coefficient step-down of the light diffusion layer of gained (B), the mechanical strength of film reduces.Can think that thus the intrinsic viscosity of the crystallinity polyester that contains copolymer composition of formation light diffusion layer (B) is high more good more.But the inventor has found astonishing relevance as follows between the intrinsic viscosity of this polyester and surface haze.
If the intrinsic viscosity of this crystallinity polyester uprises, the shearing force under then fusion is stirred will increase.Thus, if this crystallinity polyester and immiscible with it adjuvant are mixed in extruder, then the intrinsic viscosity of this crystallinity polyester is high more, and the shearing force under fusion is stirred just increases, and the dispersiveness of adjuvant is high more.This can think because adjuvant because of the shearing force of solvent grain refine takes place.At this moment, the particle diameter of adjuvant will diminish, and can't obtain effective dispersion diameter with the degree of light diffusion layer (B) surface being given good concaveconvex structure, and surface haze reduces.Hence one can see that, is taking into account of the mechanical strength of realizing light diffusion layer (B) and good light characteristic, and the intrinsic viscosity that preferably will constitute the crystallinity polyester that contains copolymer composition of light diffusing resin layer is controlled to be the scope of regulation.
Lower limit as the intrinsic viscosity of this crystallinity polyester is preferably 0.50dl/g, more preferably 0.52dl/g.If intrinsic viscosity, then is provided with foreign matter less than 0.50dl/g and removes with under the situation of filtrator in molten thread, the tendency that the ejection stability when having the extruding of molten resin reduces.In addition, the upper limit as the intrinsic viscosity of this crystallinity polyester is preferably 0.61dl/g, more preferably 0.59dl/g.Surpass under the situation of 0.61dl/g in intrinsic viscosity, the dispersion diameter of above-mentioned adjuvant in polyester diminishes, the tendency that has light diffusing to reduce.
(6) control of the melt viscosity difference of substrate polymer and immiscible resin
The inventor finds, in the melt viscosity difference of the adjuvant of this crystallinity polyester that constitutes light diffusion layer (B) and immiscible property; And following described relevance arranged between the surface haze of film.Utilize the non-adjuvant that mixes in the light diffusion layer (B) to form concave-convex surface, the surface haze that obtains stipulating among the present invention.The crystallinity polyester that contains copolymer composition that constitutes light diffusion layer (B) is stirred in extruder with the adjuvant of immiscible property and mixes.As the form of the adjuvant of immiscible property, preferred thermoplastic resin, however be under the situation of same degree at the melt viscosity of this crystallinity polyester and the melt viscosity of this adjuvant, two kinds of compositions disperse easily, this adjuvant generation grain refine.If the dispersion diameter of this adjuvant diminishes, then can't obtain good concaveconvex structure on light diffusion layer (B) surface, surface haze reduces.Thus, among the present invention, the melt viscosity difference of the crystallinity polyester that contains copolymer composition of formation light diffusion layer (B) and immiscible adjuvant is the bigger the better.This melt viscosity difference under 270 ℃ is preferably more than the 35Pas, more preferably more than the 40Pas.If melt viscosity difference is more than the 35Pas, then the adjuvant in the polyester of adjuvant just has good dispersion diameter, can obtain good light diffusing.
(7) control of draft temperature and temperature condition of heat treatment
The mechanical characteristic of film or optical characteristics also can utilize film forming condition to control.If owing to improve the draft temperature of film, then drawing stress will reduce, so the orientation coefficient step-down, the generation in space is suppressed.In addition,, therefore consider, preferably at high temperature stretch from the aspect of taking into account total light penetration and light diffusing owing to also form easily the concave-convex surface that the adjuvant by immiscible property causes.In addition, if at high temperature heat-treat, then the space disappears, and can reduce inner turbidity, and in addition, hot size changing rate also can diminish, and is difficult to produce curling in the thermal treatment.But if improve draft temperature, then the thickness variation of film will become greatly, produces uneven thickness etc., is difficult to obtain the original mechanical characteristic of film.In surface light-diffusing polyester film of the present invention, in order to realize taking into account of good mechanical characteristic, total light penetration and light diffusing, the best control film forming condition corresponding suitably, the particularly temperature when temperature during control stretching and thermal treatment with resin properties or demand characteristics.
When making surface light-diffusing polyester film of the present invention in that vibrin is stretched, the temperature during its cross directional stretch is preferably in 120 ℃ to 160 ℃ the temperature range.In addition, for thermal treatment, preferably under the condition more than air quantity 25m/ minute, in 235 to 250 ℃ temperature setting range, in 5 seconds to 100 seconds scope, heat-treat.And, at this moment,, then have the situation that optical characteristics reduces if film temperature surpasses 240 ℃.In addition, also can implement vertical or horizontal relaxation processes with the thermal treatment while or after thermal treatment.
In order to reach technical scheme 1 described important document (1), can control and reach by implementing above-mentioned approach (the 1)～condition of (3).
In order to reach technical scheme 1 described important document (2), can control and reach by implementing above-mentioned approach (the 4)～condition of (7).
In order to reach technical scheme 1 described important document (3), can control and reach by implementing above-mentioned approach (the 3)～condition of (7).
In order to reach technical scheme 1 described important document (4), can control and reach by implementing above-mentioned approach (the 3)～condition of (7).
In order to reach technical scheme 1 described important document (5), can control by the condition of implementing above-mentioned approach (1)～(4), (7) and reach.
Think among the present invention,, just can take into account the above-mentioned characteristic that belongs to antinomy, obtain the effect of regulation by the approach of above-mentioned (1)～(7) is reciprocally related.But, so long as in the scope that does not break away from purport of the present invention, then also can utilize with above-mentioned method diverse ways and reach.Can enumerate approach as follows specifically.
In above-mentioned (2), provided the method that suppresses the generation of curling that causes by bimetal structure.Above-mentioned explanation discloses following technological thought, promptly, if after having taken into account light penetration and light diffusing to heavens, how, reduce linear expansion coefficient poor of light diffusion layer (B) and supporting course (A), just can obtain surface light-diffusing polyester film of the present invention, yet, can utilize diverse ways to obtain surface light-diffusing polyester film of the present invention so long as those skilled in the art just can utilize at an easy rate with above-mentioned method diverse ways and implement this technological thought.
Promptly, even the fusing point difference of the equal polyester of crystallinity polyester/crystallinity that constitutes supporting course (A) and the crystallinity polyester that constitutes light diffusion layer (B) greater than 25 ℃ situation under, also can be by in stretching process, giving difference to the supporting course (A) and the draft temperature of the face separately of light diffusion layer (B), and difference is being set aspect the state of orientation that causes by stretching in supporting course (A) face side and light diffusion layer (B) face side, linear expansion coefficient by the controlling diaphragm two sides poor, the surface light-diffusing polyester film of the generation of curling that causes by bimetal structure of just can being inhibited.
In addition, in above-mentioned (5), provided the method for utilizing the concave-convex surface that forms by dispersed adjuvant to come the control surface turbidity.In the above-mentioned explanation, disclose dispersion diameter that how to control adjuvant and be good technological thought, yet so long as those skilled in the art just can utilize at an easy rate with above-mentioned method diverse ways and implement this technological thought.
Promptly, even the intrinsic viscosity at the crystallinity polyester that contains copolymer composition that constitutes light diffusion layer (B) surpasses under the situation of 0.61dl/g, also can be by the polymer pipe after the blend portion in the control extruder to mouthful hold-up time of the adjuvant of mould outlet, guaranteed to take place the time of the adjuvant cohesion of grain refine, the dispersion diameter of control adjuvant, thus the surface haze that causes by formed concave-convex surface just can be obtained.In addition, by the slit separation of control T shape mould, the shearing force when controlling the molten resin ejection, thus can control the dispersion diameter of adjuvant.In addition, by in dispersed dissolving resin temporarily, in the polymer pipe behind mixing, add have make grain refine the polycoagulant of effect of adjuvant cohesion, just can control the dispersion diameter of adjuvant.For example,,, promote the cohesion of styrene resin, can obtain effective dispersion diameter for the light diffusion by adding acrylic acid-styrol copolymer etc. as polycoagulant using polystyrene resin to be used as under the situation of adjuvant.This kind acrylic acid-styrol copolymer also can wait by the styrene monomer copolymerization with 1 mole glycidyl methacrylate and 2 moles and obtain.
In addition, in the explanation of above-mentioned (7), provided by the draft temperature that improves film to come control stretching stress, suppress the method that the space produces.In the above-mentioned explanation, provided and how to reduce drawing stress and be good technological thought, yet so long as those skilled in the art just can utilize at an easy rate with above-mentioned method diverse ways and implement this technological thought.That is, even when the film draft temperature is very low, also can draw speed be reduced by using biaxial orientation stretching machine simultaneously, control stretching stress suppresses the space and produces.
In addition, formation and characteristic for being used to obtain surface light-diffusing polyester film of the present invention are described in detail as follows.
(raw material)
The equal polyester of crystallinity that uses as the pleurodiaphragmatic in terspace material among the present invention is with aromatic dicarboxylic acid or its esters such as terephthalic acids, isophthalic acid, naphthalene diacid; With ethylene glycol, diglycol, 1, ammediol, 1, glycol polycondensation such as 4-butylene glycol, neopentyl glycol and the polyester made.These polyester make aromatic dicarboxylic acid and glycol directly the direct polymerization manufacturing of reaction except utilizing, and can also utilize after the Arrcostab that makes aromatic dicarboxylic acid and glycol carry out ester exchange reaction and make with the ester-interchange method of its polycondensation or with the methods such as diglycol ester polycondensation of aromatic dicarboxylic acid.
As the typical example of above-mentioned polyester, can enumerate polyethylene terephthalate, polytrimethylene-terephthalate, poly terephthalic acid butylidene ester or gather 2,6-naphthalenedicarboxylic acid second diester.Above-mentioned polyester both can be a homopolymer, also can be the ternary material that substantially do not hindered in its crystalline scope copolymerization.In the middle of these polyester, preferred ethylene glycol terephthalate unit or 2,6-glycol naphthalendicarboxylate be 70 moles of % above, be preferably above, the 90 moles of polyester that % is above more preferably of 80 moles of %.
In addition, the crystallinity polyester that contains copolymer composition that can be used for the present invention is meant with the equal polyester of above-mentioned crystallinity as basic framework, imported the polyester of the 3rd composition (copolymer composition) in main chain, its structure, molecular weight and form unqualifiedly are arbitrarily.
In addition, surface light-diffusing polyester film of the present invention preferably will comprise the aromatic dicarboxylic acid composition; With comprise ethylene glycol, and the copolyester of at least a diol component of chain aliphatic diol or alicyclic diol be used for part of raw materials or all.
As a chain aliphatic diol, for example can neopentyl glycol, 1 be shown example, 2-propylene glycol, 1,2-butylene glycol etc.In addition, as alicyclic diol, can 1,4 cyclohexane dimethanol, tristane dimethanol etc. be shown example.
In the middle of them, preferred especially neopentyl glycol or 1,4 cyclohexane dimethanol.In addition, among the present invention, except above-mentioned diol component also with 1, ammediol or 1, the 4-butylene glycol is preferred embodiment as copolymer composition.With these glycol as copolymer composition, the way that imports in above-mentioned scope, uses is suitable for giving above-mentioned characteristic, in addition, consider it is preferred from the aspect that reduces space in the light diffusion layer, takes into account light penetration and light diffusing to heavens.
In addition, as required, also can be in above-mentioned polyester with one or more of dicarboxylic acid composition as follows and/or diol component as copolymer composition and use.
As other the dicarboxylic acid composition that can form property derivant and usefulness with terephthalic acids or its ester, can enumerate (1) isophthalic acid, 2,6-naphthalene diacid, diphenyl-4, aromatic dicarboxylic acid or their ester formation property derivants such as 4 '-dicarboxylic acid, biphenoxyl ethane dicarboxylic acid, diphenyl sulphur dicarboxylic acid, isophthalic acid-5-sodium sulfonate (5-Na ト リ ウ system ス Le ホ イ ソ Off タ Le), phthalic acid; (2) aliphatic dicarboxylic acid or their ester formation property derivants such as oxalic acid, succinic acid, hexane diacid, decanedioic acid, dimer acid, maleic acid, fumaric acid, glutaric acid; (3) alicyclic dicarboxylic acid such as cyclohexane diacid or their ester form the property derivant; (4) oxygen yl carboxylic acid such as p-methoxybenzoic acid, oxygen base caproic acid or their ester are formed property derivant etc.
On the other hand, as can be, for example can enumerate aromatic diol such as aliphatic diols such as pentanediol, hexanediol, bisphenol-A, bisphenol S and their ethylene oxide adduct, diglycol, triethylene glycol, dimer diol etc. with other diol component of ethylene glycol and chain aliphatic diol and/or alicyclic diol and usefulness.
In addition, as required, also can be on above-mentioned polyester polyfunctional compounds such as copolymerization trimellitic acid, trimesic acid, trimethylolpropane again.
Used catalyzer when making above-mentioned polyester for example can use alkali earth metallic compound, manganese compound, cobalt compound, aluminium compound, antimonial, titanium compound, titanium/Si composite oxide, germanium compound etc.In the middle of them, consider preferred titanium compound, antimonial, germanium compound, aluminium compound from the aspect of catalytic activity.
In the above-mentioned polyester of manufacturing, preferably add phosphorus compound as thermal stabilizer.As above-mentioned phosphorus compound, for example preferably phosphoric acid, phosphorous acid etc.
Surface light-diffusing polyester film of the present invention both can fixedly use above-mentioned copolyester former state as the pleurodiaphragmatic in terspace material, also copolyester that can copolymer composition is many is adjusted with equal polyester (for example polyethylene terephthalate) blend and is copolymerized into component.
Particularly, make film, just can make and take into account, have high-melting-point (thermotolerance), contain the crystallinity polyester of copolymer composition with the equal light diffusing of the situation of only using copolyester with always in the light penetration by the blending method that uses the latter.
In addition, also can adopt following method, that is,, utilize both ester exchange reactions, import the 3rd composition (copolymer composition) in the chain linked to owner two kinds of different crystallinity polyester melting mixing.Particularly, consider from the aspect that reduces the space, more preferably with above-mentioned copolyester and polyethylene terephthalate, and polyethylene terephthalate beyond at least a above blend of equal polyester (for example PEN or polybutylene terephthalate), as the raw material use of surface light-diffusing polyester film of the present invention.
And, in the polyester that constitutes above-mentioned supporting course (A), preferably do not contain particle in fact.In addition, in the crystallinity copolyester that constitutes light diffusion layer, preferably do not contain adjuvant described later particle in addition in fact.Above-mentioned what is called " does not contain particle in fact " and is meant, for example for the situation of inorganic particulate, utilize x-ray fluorescence analysis with inorganic elements when quantitative for 50ppm below, be preferably below the 10ppm, be preferably the content below the detection limit especially.By using the pure polyester raw material that does not have impurity like this, just can suppress the generation of the optical defect of LCD.
(adjuvant＜concave-convex surface additives 〉)
Adjuvant of the present invention adds for purpose additional concavo-convex to the light diffusion layer surface, that embody the surface light-diffusing energy.(penetrating from light diffusion layer) light of injecting to light diffusion layer is attached to the concavo-convex edge direction refraction diffusion at random on film surface, embodies surface light-diffusing.Above-mentioned adjuvant so long as with polyester be the material of immiscible property, just without any restriction, can be arbitrarily, yet preferably use material as follows.
(with polyester be the thermoplastic resin of immiscible property)
The most excellent adjuvant that can be used for the present invention is to be the thermoplastic resin of immiscible property with above-mentioned polyester.Be following technology, utilize the immiscible property of polyester and thermoplastic resin, in manufacturing process's (melt extruding operation) of biaxial stretching film, in the matrix that constitutes by polyester, disperse to form by with this polyester be the regional structure (domain) that the thermoplastic resin of immiscible property constitutes, utilize as concave-convex surface formation agent.By using this technology, just can filter foreign matter with high-precision filtrator in melt extruding in the operation of film, reach as the LCD necessary degree of purity of film.
Different with it, under polymer particle that will non-meltbility described later or situation that inorganic particulate uses as adjuvant, the limit is being arranged, the very difficult foreign matter of removing accurately aspect the fineness of the mesh of the filtrator of the manufacturing process that can be used for film.In addition, under the situation of having used polymer particle or inorganic particulate, in the interface of particle and polyester, produce the space easily, be difficult to take into account to heavens light diffusing and total light penetration.
As can as above-mentioned adjuvant with polyester be the thermoplastic resin of immiscible property, for example can enumerate following material.That is, acryl resin such as polystyrene such as polyolefin, polycarbonate, random polystyrene, syndiotactic polytyrene, isotactic polyphenylacetylene, polyamide, polyethers, polyesteramide, polyphenylene sulfide, polyphenylene oxide, polyether ester, Polyvinylchloride, polymethacrylate such as tygon, polypropylene, polymethylpentene, various cyclic olefin based polymers and with them as the multipolymer of principal ingredient or the potpourri of these resins etc.
Wherein, in order to make film with high light penetration, the non-crystalline transparent polymer of preferred especially use.Different with it, under the situation that crystalline polymer is used as adjuvant, crystalline polymer generation gonorrhoea and make the inside turbidity of film become big, light penetration might reduce.
As non-crystalline transparent polymer that can be used for the present invention, for example can enumerate following material.That is, can polystyrene (PS resin), acrylonitrile styrene copolymer (AS resin), styrene-methyl methacrylate copolymer (MS resin), cyclic olefin based polymer, methacrylic resin, PMMA etc. be shown example.
In the middle of them, consider, more preferably the surface tension of polymkeric substance and the approaching non-crystalline transparent polymer of matrix that constitutes by polyester from the aspect that reduces the space.As the non-crystalline transparent polymer of this kind surface tension near polyester, preferred especially polystyrene (PS resin), PMMA.
(non-meltbility polymer particle)
For can be used as the non-meltbility polymer particle that adjuvant of the present invention uses, so long as can not cause the particle of the flow deformation that is caused by fusing when using fusing point test device (Stanford Research Systems corporate system, MPA100 type) to heat up with 10 ℃/minute from 30 ℃ to 350 ℃, its composition is just unqualified.For example can enumerate acrylic resin, polystyrene resin, polyolefin-based resins, polyester based resin, polyamide-based resin, polyimide and be resin, fluorine resin, urea is that resin, melamine are resin and silicon-type resin etc.The shape of particle is preferably spherical or ellipticity.In addition, this particle both can have pore, also can not have.In addition, also can and use both.
Under the situation that above-mentioned non-meltbility polymer particle is made of the polymkeric substance with the fusing point more than 350 ℃, also can use the non-cross-linked polymer particle, yet consider the preferred cross-linking polymer particle that constitutes by polymkeric substance that uses from stable on heating aspect with cross-linked structure.
The mean grain size of above-mentioned non-meltbility polymer particle is preferably 0.1～50 μ m.The lower limit of the mean grain size of above-mentioned non-meltbility polymer particle is 0.5 μ m more preferably, is preferably 5 μ m especially.In order to bring into play good light diffusion effect, the mean grain size of above-mentioned non-meltbility polymer particle is preferably more than the 0.1 μ m.
On the other hand, the upper limit of the mean grain size of above-mentioned non-meltbility polymer particle is 30 μ m more preferably, are preferably 20 μ m especially.Mean grain size at above-mentioned non-meltbility polymer particle surpasses under the situation of 50 μ m, and film strength or total light penetration reduce easily.This non-meltbility polymer particle preferably uses the particle with sharp-pointed as far as possible size-grade distribution.
Above-mentioned non-meltbility polymer particle both can use a kind of, also can use two or more.If will have different multiple non-meltbility polymer particle of sharp-pointed size-grade distribution (particle diameter that means particle is a homogeneous) and mean grain size and usefulness,, be preferred embodiment therefore then owing to can suppress to become the sneaking into of oversize grain of the defective of film.
And the mensuration of the mean grain size of above-mentioned particle utilizes following method to carry out.
Utilize scanning electron microscope (SEM) that particle is taken pictures, reach the multiplying power of 2～5mm with the size of 1 particle of minimum, measure 300～500 particles maximum gauge (the most away from 2 between distance), with its mean value as mean grain size.In addition, contained particle is under the situation of independent particle in film, measures the maximum gauge of each particle, with its mean value as mean grain size.
(inorganic particulate)
As can enumerating silica, lime carbonate, barium sulphate, calcium sulphate, aluminium oxide, porcelain earth, talcum etc. as the inorganic particulate of adjuvant.
The mean grain size of above-mentioned inorganic particulate as a rule is preferably 0.1～50 μ m.More preferably 0.5～30 μ m, more preferably 1～20 μ m.If mean grain size less than 0.1 μ m, then can't obtain good light diffusion effect.On the contrary, surpassing under the situation of 50 μ m, owing to can cause the reduction etc. of film strength, therefore not ideal enough.The size-grade distribution of this inorganic particulate is preferably used sharp-pointed as far as possible distribution.Be necessary to widen under the situation of size-grade distribution, preferably the particle with sharp-pointed size-grade distribution cooperates a plurality of dealing with.Utilize this countermeasure, can suppress to become the sneaking into of particle of thick particle diameter of the defective of film.
And the mensuration of the mean grain size of above-mentioned particle utilizes following method to carry out.
Utilize scanning electron microscope (SEM) that particle is taken pictures, reach the multiplying power of 2～5mm with the size of 1 particle of minimum, measure 300～500 particles maximum gauge (the most away from 2 between distance), with its mean value as mean grain size.Measure the maximum gauge of particle contained in the film, with its mean value as mean grain size.
The shape of above-mentioned inorganic particulate is unqualified, yet preferably is essentially spherical or spherical shape.In addition, no matter this particle is that atresia or any of porous type can.In addition, also can and use both.
Used adjuvant both can use a kind of in above-mentioned three kinds among the present invention, also can be with two or more and use.
(mixture ratio of adjuvant)
The light diffusion layer of surface light-diffusing polyester film of the present invention by the crystallinity polyester that contains above-mentioned copolymer composition of 50～99 mass parts and 1～50 mass parts with this polyester be that the complexing compositions of the adjuvant of immiscible property constitutes.Both preferred cooperation ratios are 75～98 mass parts polyester and the cooperating of 2～25 mass parts adjuvants, and more preferably 80～97 mass parts polyester and 3～20 mass parts adjuvants cooperates.
In addition, under the situation of mixture ratio less than 1 mass parts of above-mentioned adjuvant, the concavo-convex scarce capacity that forms on the film surface of being brought by adjuvant can't obtain enough surface light-diffusing energy.On the other hand, the mixture ratio at adjuvant surpasses under the situation of 50 mass parts the light scattering increase in adjuvant/polyester interface, and the increase of the drawing stress of polyester, the easy space that produces around adjuvant.Consequently, the inside turbidity of light diffusion layer becomes big, and total light penetration has the tendency of reduction.In addition, adjuvant comes off easily when the two-way stretch of film, and this cast becomes the reason of foreign matter.
[characteristic of light diffusing polyester film]
(planar orientation coefficient)
The planar orientation coefficient of surface light-diffusing polyester film of the present invention (Δ P) be 0.08～0.16 ten minute important.The lower limit of planar orientation coefficient (Δ P) more preferably 0.09 is preferably 0.10 especially.On the other hand, the upper limit of planar orientation coefficient (Δ P) more preferably 0.15 is preferably 0.14 especially.
If planar orientation coefficient (Δ P) is below 0.16, then can form the concavo-convex of light diffusion layer (B) surface effectively, can bring into play the light diffusion effect (surface haze) that produces by concave-convex surface, therefore preferred.
In addition, under planar orientation coefficient (Δ P) surpasses 0.16 situation, though according to the kind of used adjuvant and difference, yet the quantity in the space that around adjuvant, produces or the big or small tendency that has increase.Just have scattering-in (inner turbidity) thus and become the tendency that big, total light penetration reduces.In any case, (Δ P) is under the situation below 0.16 at the planar orientation coefficient, can realize taking into account of total light penetration and light diffusing.
On the other hand, if the planar orientation coefficient is more than 0.08, then can bring into play the feature as biaxial stretching film, thermotolerance, physical strength, thickness evenness etc. are good, can suppress to heat curling generation.
The method that the planar orientation coefficient is controlled to be in the above-mentioned scope is arbitrarily, for example can control by the ratio that is adjusted at the copolymer composition in the above-mentioned crystallinity polyester that contains copolymer composition.If increase in the light diffusion layer or supporting course (A) in the ratio of copolymer composition, then the planar orientation coefficient will reduce, and in addition, if reduce the ratio of copolymer composition, the planar orientation coefficient is risen.The ratio of preferred copolymer composition as previously mentioned.
In addition, also can utilize polymer blending or copolymerization, control the above-mentioned glass temperature that contains the crystallinity polyester of copolymer composition.If the reduction glass temperature, the orientation in the two-way stretch operation then described later reduces, and can reduce the planar orientation coefficient.In addition, reduce the intrinsic viscosity of raw material polyester used in the light diffusion layer, also can obtain identical effect.Preferred intrinsic viscosity as previously mentioned.
In addition, utilize the adjustment of two-way stretch condition described later, also chain of command orientation coefficient to a certain extent.In order to reduce the planar orientation coefficient, as long as set the draft temperature of longitudinal stretching or cross directional stretch higher, or set stretching ratio lower, perhaps heat treatment temperature is set higher getting final product.To narrate in the back for preferred two-way stretch condition.
(characteristic of optics)
In addition, be characterised in that among the present invention that surface haze is more than 15%, and inner turbidity is less than surface haze.Surface haze is the characteristic that derives from the concave-convex surface of light diffusion layer.Thus, penetrating from film surface in the light, perhaps injecting in the film surface at light, because of light by the refraction of the concave-convex surface of light diffusion layer, and surface haze is improved.So surface haze is irrelevant basically with total light penetration.Thus, by improving surface haze, just can under the state of the reduction that has suppressed total light penetration, improve light diffusing.
On the other hand, inner turbidity is the characteristic that derives from the light scattering of film inside.Thus, total light penetration can reduce because of the backscattered influence of incident light.So, having excellent light diffusing in order to make, a light diffusing polyester film of high total light penetration, valid approach is to improve surface haze, and reduce inner turbidity as much as possible.
The surface haze of surface light-diffusing polyester film of the present invention is more than 15%.Be limited to 20% under surface haze preferred, be limited to 25% under preferred, be limited to 30% under particularly preferred.If surface haze is more than 15%, then can look like to bring into play effective diffusion effect to the printing decorative pattern of light guide plate, the lamp of cold-cathode tube, can obtain effective light diffusing energy as the light diffusing film.
On the other hand, the preferred higher limit of surface haze is 60%, and preferred higher limit is 70%, is limited to 80% on further preferred.If surface haze is below 80%, then can suppress inner turbidity, total light penetration has the tendency that uprises.
In addition, inner turbidity is very important less than surface haze.The higher limit of inner turbidity is preferably 40%, and more preferably 30%, more preferably 20%, be preferably 10% especially.
Identical at inner turbidity with surface haze, perhaps surpass under the situation of surface haze, inner turbidity will be undertaken the main part of the light diffusion function of film, and in the inner generation of film (being accompanied by backscattered) light scattering, total light penetration reduces widely.On the other hand, the lower limit of inner turbidity is preferably 1%.Inner turbidity less than 1% film in, have the tendency that can't obtain enough surface haze.
In addition, surface light-diffusing polyester film of the present invention preferably has the total light penetration more than 86%.The lower limit of preferred light penetration is 87%, and further preferred lower limit is 88%.
In addition, the light diffusing of light diffusing film can for example can utilize as vividness and estimate quantitatively.So-called is the index of the distinct degree of expression when passing film and watching light source such as fluorescent light as vividness, is to measure as vividness according to JIS K 7105 " the optical characteristics test methods of plastics ", the picture vividness of utilizing usual way to estimate.The picture vividness is more little, shows that then disguise is good more, and light diffusing can be excellent more.
In the surface light-diffusing polyester film of the present invention, be in the penetrant method of 2mm, can obtain the picture vividness below 40% at the optical comb width.The higher limit of preferred picture vividness is 20%, and preferred higher limit is 15%.And, the smaller the better as vividness, however if vividness is reduced to more than the essential degree, inner turbidity will uprise, and total light penetration reduces.Among the present invention, be preferably 1%, more preferably 3% as the lower limit of vividness.
In addition, the light diffusing of light diffusing film can for example can utilize and to have used the light intensity that sees through of color technical institute system goniophotometer GP-200 in the village further to estimate quantitatively.To be made as I (0) through the value of 0 degree of the light angle in the light intensity, the value of light angle N degree is made as I (N), with utilize that following calculating formula tries to achieve see through light strength ratio and be made as S (N) time, if the value of the S when for example N=1 spends (1) is big, then will be become many through light what 0 periphery that sees through light of spending spread, therefore the distinctiveness of the picture that passes film and see can be reduced, good disguise can be obtained.In the surface light-diffusing polyester film of the present invention, can obtain S (1) and be the value more than 75%.It is big more to see through light strength ratio, shows that then disguise is good more, and light diffusing is excellent more.If the value of S (1) is less than 75%, then light diffusing reduces, and can't obtain good disguise, and is therefore not ideal enough.
S(N)＝I(N)/I(0)×100
And, though it is just excellent more to see through the big more light diffusing of light strength ratio, yet, then often have the situation that I (0) reduces if want to increase to more than the essential degree with seeing through light intensity, consequently, the front face brightness of backlight unit reduces.The higher limit of S in the surface light-diffusing polyester film of the present invention (1) is preferably 99%, and more preferably 95%, more preferably 85%.
(characteristic of mechanics)
In addition, among the present invention,, therefore can obtain thermotolerance, physical strength and the excellent thickness and precision of the original excellence of biaxial stretching film owing to use the crystallinity polyester as the raw material of film.
With regard to thermotolerance, 150 ℃ size changing rate is laterally, all be preferably below 6% on vertically, is limited to 4% on preferred, is limited to 3% on particularly preferred.Be limited to 2.5% on further preferred, be limited to 2% on further preferred, be limited to 1.5% on particularly preferred, be limited to 1% on further particularly preferred.On the other hand, 150 ℃ laterally, size changing rate is the smaller the better longitudinally, yet can think that 0% is lower limit.Under size changing rate is situation below 3%, at high temperature the processing or the use under the hot environment, change in size or planarity are worsened, can keep good planarity.Consequently, can reach the original purpose of the light diffusing film that the brightness homogenization of the light-emitting face of backlight unit is such.And, the so-called flow direction (coiling direction) that laterally is meant the film when making film among the present invention, what is called vertically is meant vertical with it direction.
In addition, no matter laterally still longitudinally on which direction, the lower limit of the tensile strength of film all is preferably 100MPa, and more preferably 130MPa is preferably 160MPa especially.If tensile strength is more than the 100MPa, then can bring into play the intensity of the mechanics of biaxial stretching film, not good situation such as in the manufacturing procedure of film, be difficult to crack, break, fracture, tear.
In addition, the uneven thickness of surface light-diffusing polyester film of the present invention is preferably below 5.0%.
Under the uneven thickness of film is situation below 5.0%, when being wound on film on the reel, be difficult to produce wrinkle or projection, can keep planarity.Consequently, the brightness of the light-emitting face of the backlight unit homogeneous that becomes can be realized the original purpose of light diffusing film.
In addition, surface light-diffusing polyester film of the present invention is preferably below the 5mm in the crimp values of 100 ℃ of following heat treated after 30 minutes under uncharged state.
Under situation about crimp values being made as below the 5mm, the disposal during operation under for example the nothing when packing final products into as the light diffusing film stretches will become good.In addition, even in the use under processing at high temperature or the hot environment, the distortion that also can suppress film produces, and can realize the original purpose of the light diffusing film that the brightness homogenization of the light-emitting face of backlight unit is such.
With regard to the inhibition of curling, as previously mentioned, can adjust by the control supporting course (A) and the fusing point difference of light diffusion layer (B), yet furthermore, headed by the crystallization degree of the film thickness direction that is caused for the cooling velocity difference of controlling the table back side cooling when extruding, by curling that the structure difference at the film table back side of being given in each operation such as preheating, stretching, cooling, coiling causes, the method that advantageous applications is following etc., promptly, the structure that produces the film table back side energetically is poor, it is poor to remedy the certainty structure, makes crimp values near zero.
Specifically, by in stretching process such as longitudinal stretching or cross directional stretch and heat treatment step, the temperature or the heat at the film table back side is made as different values, come the degree of orientation at the controlling diaphragm table back side independently, take into account the structure at the film table back side or the condition of rerum natura by employing, and realize zero film that curls.
In addition, as the basic important document that is used for stably producing under the very low state that curls on whole width spreading all over, the uneven few drawing process rules of used thickness also are very important.
More particularly, preferably by for the longitudinal curl of just making behind the film, the structure at the film table back side during the control longitudinal stretching is poor, for horizontal curling, the structure at the controlling diaphragm table back side is poor when cross directional stretch and heat setting, and add reciprocal internal modification, and take into account the internal modification that the structure difference by the film table back side that certainly leads to causes, suppress curling.
In addition, the thickness of surface light-diffusing polyester film of the present invention is arbitrarily, is not particularly limited, yet is preferably the scope of 25～500 μ m, more preferably the scope of 75～350 μ m.
(manufacturing of biaxial stretching film)
Among the present invention, as the method that satisfies above-mentioned characteristic, the manufacture method below for example preferred the use.
Below, for the preferred manufacture method of surface light-diffusing polyester film of the present invention, at the particle of pet copolymer (the following polyester that also abbreviates as sometimes) is elaborated as the typical example as the crystallinity polyester that contains copolymer composition of the raw material of light diffusion layer (B).
The pipe arrangement that typically uses regulation when transferring above-mentioned particle utilizes air to transport to carry out, sneak in order to prevent dust, and the air of this moment preferably adopts the air that uses the cleaning of HEPA filtrator to change.This moment used HEPA filtrator preferably to use the nominal filtering accuracy be the filtrator with performance of the dust more than the 0.5 μ m that can intercept 95% or more.
At first, as the pleurodiaphragmatic in terspace material, with polyester, with polyester be that the thermoplastic resin of immiscible property utilizes vacuum drying or heated-air drying respectively, be dried to moisture rate and be less than 100ppm.Then,, supply with, melt extrude with sheet to extruder with each raw material metering, mixing.Then, use static to apply method, metal rotation roller (chilled roll) driving fit with the sheet and the surface temperature control of molten condition is 10～50 ℃ blows cold wind and carries out cooling curing from opposite one side in addition, and the PET sheet is not stretched.
At this moment, in order to suppress production of foreign matters such as deterioration thing, preferably with the fusing department of extruder, blend portion, polymer pipe, gear-type pump, be controlled to be 220～290 ℃, polymer pipe thereafter, the resin temperature of mouthful mould are controlled to be 210～295 ℃ until the resin temperature of filtrator.
In addition, be retained as the place arbitrarily of 275 ℃ of uniform temperatures,, carry out high precision and filter in order to remove foreign matter contained in the resin at molten resin.Used filter material in filtering as the high precision of molten resin, the filter material of stainless steel sintered body is being removed condensation product or the dystectic organic aspect of performance excellence as major component with the Si in the resin, Ti, Sb, Ge, Cu, thereby preferred.Carrying out in high precision filters, owing to be lower than in the temperature of molten resin under 275 ℃ the situation, filter is pressed and will be risen, and therefore reduces the operations such as spray volume of material resin.
In addition, the filtered particles size of filter material (initial stage filtration efficiency 95%) is preferably below the 20 μ m, is preferably especially below the 15 μ m.If the filtered particles size of filter material (initial stage filtration efficiency 95%) surpasses 20 μ m, then be difficult to remove fully the foreign matter of the above size of 20 μ m.Though because of the filtered particles size (initial stage filtration efficiency 95%) of using filter material is the high precision filtration that the following filter material of 20 μ m carries out molten resin, have the situation that productivity reduces, yet, be crucial operation for the few film of optical defect that obtains to cause by oversize grain.And, among the present invention,, just can realize aforesaid high precision filtration by use is the thermoplastic resin of immiscible property with the crystallinity copolyester as adjuvant.Here, so-called initial stage filtration efficiency is meant the numerical value that utilizes ANSI/B93.36-1973 to measure.
For with light diffusion layer (B) and supporting course (A) coextrusion and stacked, use the extruder more than 2, the raw material of each layer is extruded, use multilayer feed block (the interflow piece that for example has square interflow portion) with two-layer interflow, extrude cooling curing on casting roller and make unstretching film the mould with sheet from the mouth of slit-shaped.Perhaps also can replace the multilayer feed block and use multithread road junction mould (multimanifold die).
In addition, in the surface light-diffusing polyester film of the present invention, preferably at least one side's surface, have coating layer, more preferably have coating layer on the two sides.Preferred dried coating weight is 0.005～0.20g/m
2Scope.By surface coating layer is set, just can suppresses the catoptrical generation on film surface, further improve total light penetration at light diffusion layer.In addition, on the face of an opposite side, coating layer is set, the surface of this coating layer is implemented just can give easy-adhesion under the situation of prismatic lens processing or hard coat processing with light diffusion layer.
Under this situation, after being provided with coating layer on the unstretching film that utilizes above-mentioned method to obtain, carry out two-way stretch.No matter be to utilize simultaneously the two-way stretch method or utilize the two-way stretch method one by one can, yet under the situation of utilizing one by one pulling method, longitudinally or after laterally having carried out being provided with easy adhesive linkage on the film of uniaxial tension, stretch along orthogonal directions, carry out two-way stretch.
Being used for that coating layer is formed the method for coating on unstretching film or the monadic stretching membrane with coating fluid can select from known arbitrary method, for example can enumerate reverse roll rubbing method, intaglio plate rubbing method, lick the method for being coated with, mould is coated with method, round brush method (roll-brush), spraying process, airblade coating method, the excellent rubbing method that winds the line, pipe scraper method (pipe-doctor), dip coating, curtain coating etc., both can use these methods to brush individually, and also can be used in combination and brush.
The resin that constitutes coating layer is in prismatic lens purposes or light diffusing film purposes, consider with other the viewpoint of more excellent adaptation of optical functional layer from guaranteeing, preferably at least a above with copolymer polyester resin, polyurethane series resin or acrylic resin as major component.In addition, consider, also can recommend these resins from the viewpoint of the catoptrical generation on the surface that suppresses light diffusion layer.And in the resin that constitutes coating layer, above-mentioned what is called " major component " is meant, with respect to the resin 100 quality % that constitute this coating layer, comprises at least a of the above above-mentioned resin of 50 quality %.
And, if in order to improve the transparency of film, and in supporting course (A), do not contain particle, or only contain on a small quantity with the degree that does not hinder the transparency, then the easy sliding of film will become not enough, thereby the situation of disposal property deterioration is arranged.Thus, in above-mentioned coating layer,, preferably contain particle for the purpose of giving easy sliding.In these particles, use the minimum particle of mean grain size below the wavelength of luminous ray very important in order to ensure the transparency.
As above-mentioned particle, can enumerate inorganic particulates such as lime carbonate, calcium phosphate, silica, porcelain earth, talcum, titania, aluminium oxide, barium sulphate, calcium fluoride, lithium fluoride, zeolite, molybdenum sulfide; The cross-linked polymer particle; Organic fillers such as calcium oxalate etc.Forming under the situation of coating layer special preferred silica based on above-mentioned copolymer polyester resin.Silica is because refractive index ratio near polyester, therefore can be guaranteed the light diffusing polyester film that the transparency is more excellent, and is the most suitable in this.
Consider that from the aspect of the transparency of guaranteeing film, the property disposed, rub resistance the mean grain size of the particle that is contained in the coating layer (utilizing the average largest diameter of the particle of the number benchmark that SEM observes) is preferably 0.005～1.0 μ m.Consider that from the aspect of the transparency upper limit of the mean grain size of particle is 0.5 μ m more preferably, is preferably 0.2 μ m especially.In addition, consider that from the aspect of property disposed and rub resistance the lower limit of the mean grain size of particle is 0.01 μ m more preferably, is preferably 0.03 μ m especially.
And the mensuration of the mean grain size of above-mentioned particle utilizes following method to carry out.
Utilize scanning electron microscope (SEM) that particle is taken pictures, reach the multiplying power of 2～5mm, measure the maximum gauge of 300～500 particles with the size of 1 particle of minimum, with its mean value as mean grain size.In addition, under the situation of asking the mean grain size of calculating particle contained in the coating layer, use infiltration type electron microscope (TEM), reach the multiplying power of 2～5mm with the size of 1 particle of minimum, take the section of coated film, obtain the maximum gauge of the particle in the section that is present in coating layer.For the mean grain size of the particle that constitutes by condensed matter, be section to the coating layer of coated film, use optical microscope to take 300～500 with 200 times multiplying power, measure its maximum gauge.
Considering that from the aspect of guaranteeing the optics transparency of stacked film, adaptation, disposal, rub resistance the content of the particle in the coating layer is preferably, is 0.1～60 quality % with respect to the composition that constitutes coating layer.Consider that from the transparency and the aspect of adaptation the upper limit of the content of particle is 50 quality % more preferably, are preferably 40 quality % especially.In addition, consider that from the aspect of property disposed and rub resistance the lower limit of the content of particle is 1 quality % more preferably, is preferably 0.5 quality % especially.
Above-mentioned particle both can also can will belong to particle of the same race and the different material fit of particle diameter, yet in any case, the mean grain size of particle integral body and the content of total all preferably satisfy above-mentioned scope also with two or more.
Then, the unstretching film that utilizes above-mentioned method to obtain is carried out while two-way stretch or two-way stretch one by one, heat-treat then.
Above-mentioned two-way stretch is carried out very important in longitudinal and transverse two directions with the stretching ratio more than 2.8 times.And defined so-called stretching ratio is the actual stretching ratio that in fact film is stretched among the present invention.This stretching ratio can utilize the mass change of the unit area before and after each stretching process to grasp, and perhaps grasps by cancellate multiplier indicia is charged to unstretching film.
The stretching ratio of vertical or horizontal certain less than 2.8 times situation under, the uneven thickness of the film of gained reduces, and can't obtain the thermotolerance and the physical strength of the original excellence of biaxial stretching film.In addition, the thickness homogeneity of film worsens significantly.The following of preferred stretching ratio of the present invention is limited to 3.0 times, is limited to 3.2 times under preferred.In addition, be limited to 5 times on stretching ratio preferred.And, for suitable draft temperature condition, as previously mentioned.
Embodiment
Below, use embodiment and comparative example, the present invention is specifically described.At first, the evaluation method with characteristic value used among the present invention is expressed as follows.
[evaluation method]
(1) intrinsic viscosity
According to JIS K 7367-5, use phenol (60 quality %) and 1,1,2 as solvent, the mixed solvent of 2-tetrachloroethane (40 quality %) is 30 ℃ of mensuration.
(2) crystal melting heat, fusing point and glass temperature
Use SII Nanotechnology corporate system DSC6220 type differential scanning type calorimeter to obtain.Under nitrogen atmosphere, resin sample after the fusion, is used the liquid nitrogen quenching 300 ℃ of heating 5 minutes, chippy resin sample 10mg is heated up with 20 ℃/minute speed, carry out differential thermal analysis.Crystal melting heat is tried to achieve the DSC curvilinear integral that surrounds by defined melting hump temperature (Tpm), extrapolation fusing beginning temperature (Tim) and extrapolation fusing end temp (Tem) among the JIS-K7121-1987,91.In addition, this melting hump temperature (Tpm) is made as fusing point.In addition, based on JIS-K7121-1987,93, obtained glass temperature (Tg).
(3) melt viscosity
The viscosity of resin sample be according to JIS K 7199 " utilize the characteristic test method that flows of the plastics of plastics-capillary rheometer and narrow slit mould flow graph ", the method A (capillary die) of 5.1.3 item measures.Utilize the smart machine-processed CAPILOGRAPH 1B of Japan, use the capillary die of φ 1mm, L/D=10, in remaining 270 ℃ cylindrical shell (cylinder), the resin sample of filling dry, fusion is after about 1 minute, at 608.0sec
-1Shear rate under, measured melt viscosity.And under the situation that various kinds of resin is used as substrate polymer, the melt viscosity of above-mentioned substrate polymer is after in advance the various kinds of resin sample being mixed fully, to be filled in the cylindrical shell, utilizes method same as described above to measure melt viscosity.
(4) uneven thickness of film
To reel laterally be 3m, vertically be the continuous banded sample of the length of 5cm, utilizes the thickness of film thickness METHOD FOR CONTINUOUS DETERMINATION machine (Anritsu Co., Ltd. system) mensuration film, is recorded in the register.According to chart, obtain maximal value (dmax), minimum value (dmin), the mean value (d) of thickness, utilize following formula to calculate uneven thickness (%).And, under the situation of horizontal length, then connect together and carry out less than 3m.And, for the part that links to each other, from above-mentioned data analysis, delete.
Uneven thickness (%)=((dmax-dmin)/d) * 100
Mensuration is carried out 3 times, obtains its mean value, utilizes following benchmark evaluation.
Zero: uneven thickness is below 5%
*: uneven thickness surpasses 5%
(5) turbidity, total light penetration
The turbidity of film test sheet (blur level) and total light penetration are to measure according to JIS K 7105 " the optical characteristics test methods of plastics ".The film length direction of film test sheet vertically is provided with, light diffusion layer (B) face is provided with towards light source side ground, use the Japanese electric look system NDII-300A of industrial group type nephelometer to measure.
(6) inner turbidity, total turbidity, surface haze
Will be in the two sided coatings cedar oil (coating weight: one side 20 ± 10g/m of film test sheet
2), and with 2 turbidity less than the material of 1.0% high transparent polyethylene terephthalate (for example Japan's textile company system, A4300, thick 100 μ m) clamping as inner turbidimetric analysis turbidimetry sample.In addition, 2 should height transparent polyethylene terephthalate folders are overlapped across cedar oil, with it as blank sample.
Then, utilize (5) described method to measure the turbidity of inner turbidimetric analysis turbidimetry with sample and blank sample.After this, deduct the turbidity value of blank sample in the turbidity of turbidimetric analysis turbidimetry internally with sample, obtain inner turbidity.In addition, the total turbidity of turbidity conduct that the film test sheet that will utilize (5) described method to measure is independent deducts inner turbidity value from total turbidity value, obtain surface haze.
(7) as vividness
Utilize penetrant method to measure according to JIS K 7105 " the optical characteristics test methods of plastics " as vividness.The film test sheet is that the film length direction is made as vertical direction, and the one side of light diffusion layer (B) is measured towards light source side.As analyzer, used Suga testing machine corporate system ICM-1T type reflection property analyzer.
(8) light diffusing
Light diffusing is to use the system goniophotometer GP-200 of color technical institute in the village to measure.Light source uses Halogen lamp LED (12V, 50W), passes collector lens, pin hole, collimating apparatus and after the directional light taking-up as level at the light that will penetrate light source, is that 1% ND light filter dim light uses with transmitance.The light beam of light source diaphragm is made as 10.5mm, and the light diaphragm that is subjected to of light-receiving device is made as 9.1mm.According to the face of the light diffusion layer of the film of sample as light source side, the mode that the film interarea is vertical with light beam of light source, and, the film test sheet being placed on the specimen holder according to the mode that vertically becomes above-below direction of film.The light of injecting sample film sees through in an opposite side of film, arrives light-receiving device and measures intensity.With direction that light beam of light source is prolonged on same axis as 0 degree, with the intersection point of the optical axis of light beam of light source and the plane of incidence of film as the center with the rotation of light-receiving device along continuous straight runs, spend-80+measured through light intensity in the scopes of 80 degree with the stride of 0.1 degree.
The light intensity that sees through at angle 0 degree that will utilize said method to measure is made as I (0), and the light intensity that sees through of angle ± N degree is made as under the situation of I (N), sees through the index of light strength ratio S (N) [%] as light diffusing with what utilize that following calculating formula tries to achieve.Among the present invention, as having used S (1) with the value of the correlativity of the distinctiveness of passing the observed picture of optical diffusion film as can be seen.
S (1) is evaluated as zero more than 75%, with S (1) less than 75% be evaluated as *.
S(N)＝I(N)/I(0)×100
(8) tensile strength
Measure according to JIS C 2318-19975.3.3 (tensile strength and length growth rate).
(9) size changing rate
Measure according to JIS C 2318-19975.3.4 (change in size).
(10) planar orientation coefficient (Δ P)
According to JIS K 7142-19965.1 (A method), with sodium D-line as light source, utilize Abbe refractometer to measure the refractive index (nx) of film length direction, the refractive index (ny) of Width, the refractive index (nz) of thickness direction, utilize following formula to calculate planar orientation coefficient (Δ P).
ΔP＝(nx+ny)/2-nz
(11) crimp values
The sheet-fed shape of film with vertical 100mm, horizontal 50mm cut out, under uncharged state, with 100 ℃ of heat treated after 30 minutes, be statically placed in the protuberance of film on the glass plate of level with being made as down, with the vertical range of minimum scale 0.5mm unit use ruler mensuration glass plate, the measured value at these 4 positions is obtained mean value with four jiaos lower end of the film of holding up.3 film test sheets are carried out identical mensuration, this mean value as crimp values, is utilized following benchmark evaluation.
Zero: crimp values is below the 5mm
*: crimp values is more than the 5mm
Embodiment 1
(1) manufacturing of the equal polyester resin of crystallinity (M1)
Esterification reaction tank is heated up, in the moment that arrives 200 ℃, the slip that adding is made of terephthalic acids (86.4 mass parts) and ethylene glycol (64.4 mass parts) is while stir antimony trioxide (0.017 mass parts) and the triethylamine (0.16 mass parts) that adds as catalyzer.Then, the intensification of pressurizeing is at gauge pressure 3.5kgf/cm
2, under 240 ℃ the condition, carried out the pressurization esterification., will esterification reaction tank in return to normal pressure, add magnesium acetate 4 hydrate (0.071 mass parts), add trimethyl phosphate (0.014 mass parts) then thereafter.Then, be warmed up to 260 ℃ with 15 minutes, add trimethyl phosphate (0.012 mass parts), add sodium acetate (0.0036 mass parts) then.After 15 minutes, the esterification reaction product of gained is transplanted in the polycondensation reaction jar, under reduced pressure is warmed up to 280 ℃ at leisure from 260 ℃, carry out polycondensation reaction at 285 ℃, until the intrinsic viscosity that reaches regulation.
After polycondensation reaction finishes, (the initial stage filtration efficiency: nylon filter made device 95%) carries out filtration treatment to be of a size of 5 μ m with filtered particles, from nozzle, extrude, use the chilled water that has carried out filtration treatment (aperture: 1 μ m is following) in advance to cool off, solidify, be cut into graininess with strip.The crystal melting heat of the equal polyester resin of the crystallinity of gained (M1) is 35mJ/mg, and fusing point is 256 ℃, and intrinsic viscosity is 0.56dl/g, melt viscosity is 91Pas, and Sb content is 144ppm, and Mg content is 58ppm, P content is 40ppm, and color L value is 56.2, and color b value is 1.6.In addition, do not contain inert particle and inner precipitation particles in fact.
(2) manufacturing of copolymer polyester resin (M2)
Made copolymer polyester resin (M2) according to the method for making of (M1), they will be as 100 moles of % in terephthalic acids unit of aromatic dicarboxylic acid composition, be made as constituent as the 70 moles of % in ethylene glycol unit and the 30 moles of % in neopentyl glycol unit of diol component, intrinsic viscosity is 0.59dl/g, and melt viscosity is 121Pas.
(3) polystyrene (M3)
Used the polystyrene resin (PS) of melt viscosity as 147Pas.
(4) preparation of coating fluid (M4)
Terephthalic acids dimethyl ester (95 mass parts), dimethyl isophthalate (95 mass parts), ethylene glycol (35 mass parts), neopentyl glycol (145 mass parts), zinc acetate (0.1 mass parts) and antimony trioxide (0.1 mass parts) are added in the reaction vessel, at 180 ℃ with carrying out ester exchange reaction in 3 hours.Then, add isophthalic acid-5-sodium sulfonate (6.0 mass parts), 240 ℃ carried out esterification with 1 hour after, under reduced pressure (10～0.2mmHg) carry out polycondensation reaction with 2 hours, and having obtained number-average molecular weight and be 19500 copolyester is resin at 250 ℃.
With the copolyester of gained be resin 30 quality % aqueous dispersions, 7.5 mass parts, contain useful sulphurous acid oxygen sodium end-blocking 20 quality % aqueous solution, 11.3 mass parts, organotin catalysts 0.3 mass parts, water 39.8 mass parts and isopropyl alcohol 37.4 mass parts of self-cross linking type polyurethane series resin of isocyanate group mix respectively.
Then, add 10 quality % aqueous solution, 0.6 mass parts that fluorine is a non-ionics, as 20 quality % aqueous dispersions, 2.3 mass parts of the colloidal silica (mean grain size 40nm) of particle A, as 3.5 quality % aqueous dispersions, 0.5 mass parts of the dry process silica (mean grain size 200nm, average one-level particle diameter 40nm) of particle B.Then, with the sodium bicarbonate water of 5 quality % the pH of coating fluid is adjusted into 6.2, with filtered particles size (initial stage filtration efficiency: be the felt type polypropylene filter made device secondary filter of 10 μ m 95%), prepared coating fluid (M4).
(5) manufacturing of surface light-diffusing polyester film
As the raw material of light diffusion layer (B), the equal polyester of crystallinity (M1) 65 mass parts, copolyester (M2) 20 mass parts, polystyrene (M3) 15 mass parts, are mixed after 6 hours at 135 ℃ of drying under reduced pressure (1Torr) respectively, supply with to extruder 2.In addition, as the raw material of supporting course (A), drying under reduced pressure (1Torr) is after 6 hours respectively with the equal polyester of crystallinity (M1) 76.7 mass parts, copolyester (M2) 23.3 mass parts, and mixing is supplied with to extruder 1.
With the fusing department of each extruder, blend portion, polymer pipe, gear-type pump, be made as 275 ℃ until the design temperature of filtrator, the design temperature of the polymer pipe after the filtrator is made as 270 ℃, to use 2 laminated stream feed block stacked by each raw material that extruder 2 and extruder 1 are supplied with, from tube head, melt extrude with laminar.
And, use the gear-type pump of each layer, (A) layer and (B) layer thickness ratio is controlled to be reaches 90 to 10.In addition, in above-mentioned filtrator, all used filter material (the nominal filtering accuracy: 10 μ m particles of obstruct 95%) of stainless steel sintered body.In addition, the temperature of tube head is controlled to be makes the resin temperature of being extruded reach 275 ℃.
Using static to apply method and surface temperature the resin extruded is 30 ℃ cooling drums driving fit and cooling curing is made unstretching film.At this moment, (A) aspect is made as the face that contacts with cooling drums.In addition, cooling drums were made as 12m/ minute the draw rate of unstretching film.
Use preheat roll to be heated to be 79 ℃ the unstretching film of gained, between the different roller of peripheral speed, longitudinally be stretched as 3.4 times.At this moment, utilize the temperature of infrared radiation thermometer monitoring film, the control heater temperature makes the maximum temperature of film reach 100 ℃.
After longitudinal stretching finishes, the monadic stretching membrane of gained is cooled to 50 ℃, the one side (A layer side) at film has been coated with coating fluid (M4) afterwards.Coating fluid is controlled to be, and wet coating weight reaches about 15g/m
2Utilize drying oven with coated face drying thereafter.
Grip the two ends of monadic stretching membrane with coating layer with clamp, the guiding stenter, after being preheating to 120 ℃, is 2.5 times with 135 ℃ along cross directional stretch, be 1.6 times with 140 ℃ along cross directional stretch afterwards, then 240 ℃ of thermal treatments 10 seconds,, make the surface light-diffusing polyester film that gross thickness is 100 μ m to be cooled to 60 ℃ process along the relaxation processes of laterally carrying out 3.3%.
And, for the fusing point and the intrinsic viscosity of the polyester of measuring each layer, the ejection of (B) layer temporarily stopped and having taked the unstretching film of independent (A) layer.Similarly, the ejection of (A) layer is temporarily stopped and having taked the unstretching film of independent (B) layer.
(6) characteristic of film
The property list of the film that obtains in the present embodiment 1 is shown in Table 1.As shown in table 1, the surface light-diffusing polyester film that obtains among the present invention has the thermotolerance of the original excellence of biaxial stretching film and physical strength, thickness and precision.In addition, inner turbidity is little, has high light penetration.In addition as can be known, most the giving of total turbidity by surface haze, its light diffusing is also very excellent.
Embodiment 2
The manufacturing of＜crystallinity copolymer polyester resin (M5) 〉
Made crystallinity copolymer polyester resin (M5), they will be as 100 moles of % in terephthalic acids unit of aromatic dicarboxylic acid composition, be made as constituent as the 70 moles of % in ethylene glycol unit and the 30 moles of % in cyclohexanedimethanol unit of diol component, intrinsic viscosity is 0.60dl/g, and melt viscosity is 197Pas.
In embodiment 1, so that the content of copolymer composition, its containing ratio (copolymer composition is with respect to the molar ratio of diol component total amount) and polystyrene reaches the mode of the composition shown in the table 1, use resin M 1, M3, M5 to adjust the composition of raw materials of (A), (B) each layer.Except above-mentioned, utilize the method identical with embodiment 1, made surface light-diffusing polyester film.
The property list of the film that obtains in the present embodiment 2 is shown in Table 1.According to table 1 as can be known, present embodiment 2 is identical with embodiment 1, has excellent characteristic.
Embodiment 3
Except the two sides at film is provided with coating layer, utilizes with embodiment 1 identical method and made surface light-diffusing polyester film.Coating is used with embodiment 1 identical materials, method and is side by side carried out on the two sides, and the two sides all is controlled to be, and wet coating weight reaches about 15g/m
2
The characteristic of having represented the film of gained in the table 1.In present embodiment 3, by on the light diffusingsurface coating layer being set, compare with embodiment 1 as can be known, total light penetration further improves.
Embodiment 4
In embodiment 1,, use resin M 1～M3 to adjust (A) (B) composition of raw materials of each layer so that the content of the content of copolymer composition and polystyrene reaches the mode of the composition shown in the table 1.In addition, so that (A) thickness ratio of layer and (B) layer reaches 96 to 4 mode, control the gear-type pump of each extruder.In the making of unstretching film,, adjust the draw rate of cooling drums so that the film thickness after the two-way stretch reaches the mode of 250 μ m.In addition, alternatively disposed the multiple duct that blows out nozzle and suction nozzle (multi-duct) of cooling air continuously, carried out air-cooled to (B) aspect from the position of the about 30mm of distance cooling drums along the periphery setting of cooling drums.Except above-mentioned, utilize the method identical with embodiment 1, made unstretching film.
Then, the unstretching film of gained is used the equipment identical with embodiment 1, carry out longitudinal stretching, coating, cross directional stretch, thermal treatment under the described condition of table 1, having made gross thickness is the surface light-diffusing polyester film of 250 μ m.Coating is used with embodiment 1 identical materials, method and is side by side carried out on the two sides, the two sides all is controlled to be wet coating weight reaches about 15g/m
2
The characteristic of having represented the film of gained in the table 1.As can be known in the present embodiment owing in supporting course (A), use the equal polyester of crystallinity, therefore have the intensity more more excellent than embodiment 1, with embodiment 1 thermotolerance of excellence on an equal basis.In addition, has very excellent thickness and precision.On the other hand, in supporting course (A) and light diffusion layer (B),, can see curling of a little with it together, yet be the practical no problem scope fully that goes up in the difference that can see a little aspect the fusing point of raw material polyester.
In addition, in the present embodiment 4, compare inner turbidity with embodiment 1～3 and diminish, surface haze uprises.Accompany with it, the characteristic of total light penetration, light diffusing all is improved.Among the embodiment 4, be accompanied by the increasing to the gross thickness of film, the draw rate of cooling drums is slowed down, just the manufacturing speed with film slows down.If the film manufacturing speed is slack-off, can predict that then the stress that is applied on the film reduces when longitudinal stretching.Thus, the space that manifests around the adjuvant in light diffusion layer can tail off, and can think that shown in above-mentioned result, inner turbidity diminishes.
Embodiment 5
In embodiment 4,, use resin M 1～M3 to adjust the composition of raw materials of (B) layer so that the content of copolymer composition, its content and polystyrene reaches the mode of the composition shown in the table 1.In addition so that (A) with (B) layer thickness ratio reach 90 to 510 mode, control the gear-type pump of each extruder.In addition, utilize the method identical with embodiment 4, having made gross thickness is the surface light-diffusing polyester film of 250 μ m.
The characteristic of having represented the film of gained in the table 1.In the present embodiment 5, compare with embodiment 4, inner turbidity slightly rises, and total light penetration also slightly reduces, yet has the characteristic of enough excellences.
Embodiment 6
Except the one side (B layer side) at film is provided with coating layer, utilizes with embodiment 4 identical methods and made surface light-diffusing polyester film.
The characteristic of having represented the film of gained in the table 1.In the present embodiment 6, compare with embodiment 4, total light penetration slightly reduces, yet has the characteristic of enough excellences.
Embodiment 7,8
In embodiment 4,, use resin M 1～M3 to adjust the composition of raw materials of (B) layer so that the content of copolymer composition, its content and polystyrene reaches the mode of the composition shown in the table 1.In addition so that (A) with (B) layer thickness ratio reach 84 to 16 mode, control the gear-type pump of each extruder.In addition, utilize the method identical with embodiment 4, having made gross thickness is the surface light-diffusing polyester film of 188 μ m.The property list of the film of gained is shown in Table 1.
Embodiment 9～11
In embodiment 4,, use resin M 1～M3 to adjust the composition of raw materials of (B) layer so that the content of copolymer composition, its content and polystyrene reaches the mode of the composition shown in the table 1.In addition so that (A) with (B) layer thickness ratio reach 89 to 11 mode, control the gear-type pump of each extruder.In the making of unstretching film,, adjusted the draw rate of cooling drums so that the film thickness after the two-way stretch reaches the mode of 188 μ m.In addition, utilize the method identical, made unstretching film with embodiment 4.
Then, the unstretching film of gained is used the equipment identical with embodiment 4, carry out longitudinal stretching, coating, cross directional stretch, thermal treatment under the described condition of table 1, having made gross thickness is the surface light-diffusing polyester film of 188 μ m.Coating is used with embodiment 4 identical materials, method and is side by side carried out on the two sides, the two sides all is controlled to be wet coating weight reaches about 15g/m
2The property list of the film of gained is shown in Table 1.
Comparative example 1
In embodiment 1, the composition of raw materials of light diffusion layer (B) is changed to the potpourri of the equal polyester of crystallinity (M1) 85 mass parts, polystyrene (M4) 15 mass parts.In addition, the raw material with supporting course (A) changes to the equal polyester of crystallinity (M1).In addition, utilize the method identical with embodiment 1, having made gross thickness is the polyester film of 100 μ m.
The characteristic of having represented the film of gained in the table 1.In this comparative example 1, because the planar orientation coefficient is excessive, therefore inner turbidity is big, and total light penetration reduces significantly.And, around polystyrene, be formed with the space.
Comparative example 2
In embodiment 5,, adjusted resin M 1～M3 so that (B) content of Ceng copolymer composition reaches the mode of 22 moles of %.Use the equipment identical with embodiment 1, carry out longitudinal stretching, coating, cross directional stretch, thermal treatment under the described condition of table 1, having made gross thickness is the surface light-diffusing polyester film of 250 μ m.Coating is used with embodiment 1 identical materials, method and is side by side carried out on the two sides, the two sides all is controlled to be wet coating weight reaches about 15g/m
2
The property list of the film of gained is shown in Table 1.Though the total light penetration height of the film of this comparative example, light diffusing is also excellent, yet the planar orientation coefficient is little, and poor dimensional stability, crimp values are also big.The film of gained curls very violent, can't carry out the evaluation of thermal dimensional stability.
The industrial possibility of utilizing
Surface light-diffusing polyester film of the present invention can be used as that used light diffusing film uses in the backlight unit, lighting device of liquid crystal display etc. In addition, can be used as prismatic lens uses with base material film. So, very big to the contribution of industrial circle.
Claims (5)
1. surface light-diffusing polyester film, it is the light diffusing polyester film of being made by the double orientation polyester film, it is characterized in that, satisfies following important document (1)～(5):
(1) have supporting course and through coetrusion be laminated in described supporting course at least the one side light diffusion layer, described supporting course comprises the equal polyester of crystallinity or contains the crystallinity polyester of copolymer composition, described light diffusion layer comprise contain fusing point be 235～255 ℃ copolymer composition crystallinity polyester 50～99 mass parts and be the complexing compositions of adjuvant 1～50 mass parts of immiscible property to described polyester
(2) the planar orientation coefficient delta P with the film of following formula definition is 0.08～0.16,
ΔP＝(nx+ny)/2-nz
Wherein, nx, ny, nz represent the refractive index of length direction, the refractive index of Width, the refractive index of thickness direction respectively,
(3) surface haze is more than 15%,
(4) inner turbidity is less than surface haze,
Size changing rate in the time of (5) 150 ℃ laterally is below 3% vertical reaching, and tensile strength laterally is more than the 100MPa vertical reaching.
2. surface light-diffusing polyester film according to claim 1 is characterized in that, total light penetration is more than 86%, and comb width 2mm's is below 40% as vividness.
3. surface light-diffusing polyester film according to claim 1, it is characterized in that, on the surface of described light diffusion layer, have before the stretch orientation of film finishes setting with more than copolymer polyester resin, polyurethane series resin or acryl resin at least a as the coating layer of major component.
4. surface light-diffusing polyester film according to claim 1, it is characterized in that, on the light diffusion layer side of described light diffusing polyester film and supporting course side two sides' face, has at least a above coating layer as major component with copolymer polyester resin, polyurethane series resin or acryl resin.
5. prismatic lens surface light-diffusing polyester film, it is characterized in that, on the face of the opposite side with light diffusion layer of the described surface light-diffusing polyester film of claim 1, has at least a above coating layer as major component with copolymer polyester resin, polyurethane series resin or acryl resin.
Applications Claiming Priority (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP021798/2007 | 2007-01-31 | ||
| JP2007021798 | 2007-01-31 | ||
| JP2007118424 | 2007-04-27 | ||
| JP118424/2007 | 2007-04-27 | ||
| JP191907/2007 | 2007-07-24 | ||
| JP2007191907 | 2007-07-24 | ||
| JP2007316712A JP4257619B2 (en) | 2007-01-31 | 2007-12-07 | Surface light diffusing polyester film |
| JP316712/2007 | 2007-12-07 | ||
| PCT/JP2007/074434 WO2008093478A1 (en) | 2007-01-31 | 2007-12-19 | Surface light-diffusing polyester film |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101600977A CN101600977A (en) | 2009-12-09 |
| CN101600977B true CN101600977B (en) | 2011-08-24 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2007800501338A Expired - Fee Related CN101600977B (en) | 2007-01-31 | 2007-12-19 | Surface light-diffusing polyester film |
Country Status (4)
| Country | Link |
|---|---|
| JP (2) | JP4257619B2 (en) |
| KR (1) | KR100945656B1 (en) |
| CN (1) | CN101600977B (en) |
| TW (1) | TW200846179A (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP5163085B2 (en) * | 2007-12-11 | 2013-03-13 | 東洋紡株式会社 | Surface light diffusing polyester film |
| JP4370538B1 (en) * | 2008-08-06 | 2009-11-25 | 東洋紡績株式会社 | Surface light diffusing polyester film |
| JP2010224447A (en) * | 2009-03-25 | 2010-10-07 | Teijin Dupont Films Japan Ltd | Optical laminated film |
| JP2010247370A (en) * | 2009-04-13 | 2010-11-04 | Toyobo Co Ltd | Light diffusion polyester film for laminating curable resin |
| JP5541878B2 (en) * | 2009-04-22 | 2014-07-09 | 帝人デュポンフィルム株式会社 | Laminated polyester film for prism sheet |
| JP2010260275A (en) * | 2009-05-08 | 2010-11-18 | Mitsubishi Plastics Inc | Laminated polyester film for in-mold transfer foil |
| JP5696356B2 (en) * | 2009-11-20 | 2015-04-08 | 東洋紡株式会社 | Light diffusing polyester film |
| WO2011062081A1 (en) * | 2009-11-20 | 2011-05-26 | 東洋紡績株式会社 | Light-diffusing polyester film |
| JP4780242B2 (en) * | 2009-11-20 | 2011-09-28 | 東洋紡績株式会社 | Light diffusing polyester film |
| JP2011133871A (en) * | 2009-11-24 | 2011-07-07 | Toyobo Co Ltd | Light diffusing polyester film |
| JP2011133872A (en) * | 2009-11-24 | 2011-07-07 | Toyobo Co Ltd | Surface light-diffusing polyester film |
| KR101711689B1 (en) * | 2009-12-10 | 2017-03-02 | 도요보 가부시키가이샤 | Light diffusion film and backlight device comprising same |
| JP2012053092A (en) * | 2010-08-31 | 2012-03-15 | Mitsubishi Plastics Inc | Light-diffusion laminated polyester film for backlight |
| CN102267268B (en) * | 2011-06-17 | 2013-04-17 | 武汉金牛经济发展有限公司 | High-reflectivity reflecting film and manufacturing method thereof |
| MY172893A (en) * | 2012-05-14 | 2019-12-13 | Toyo Boseki | Polyester film and method for producing same |
| JP2014218039A (en) * | 2013-05-10 | 2014-11-20 | 三菱樹脂株式会社 | Laminated polyester film |
| JP2014233860A (en) * | 2013-05-31 | 2014-12-15 | 三菱樹脂株式会社 | Polyester film for optical use |
| CN104943305B (en) * | 2015-06-15 | 2017-01-25 | 江苏双星彩塑新材料股份有限公司 | Highly-transparent optical polyester film and preparation method thereof |
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| JP2005181648A (en) * | 2003-12-19 | 2005-07-07 | Mitsubishi Polyester Film Copp | Light scattering polyester film for prism sheet |
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| JP3921790B2 (en) | 1998-03-19 | 2007-05-30 | 東レ株式会社 | Light diffusion polyester film |
| DE10303145A1 (en) | 2003-01-28 | 2004-07-29 | Mitsubishi Polyester Film Gmbh | Matt polyester film for flexible packaging, e.g. of food or luxury goods, and for lamination, has a matt outer layer containing micronised particles in a copolyester with isophthalic acid units |
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- 2007-12-07 JP JP2007316712A patent/JP4257619B2/en not_active Expired - Fee Related
- 2007-12-19 CN CN2007800501338A patent/CN101600977B/en not_active Expired - Fee Related
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| JP2005181648A (en) * | 2003-12-19 | 2005-07-07 | Mitsubishi Polyester Film Copp | Light scattering polyester film for prism sheet |
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| JP特开2005181648A 2005.07.07 |
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| JP2009110024A (en) | 2009-05-21 |
| TWI362998B (en) | 2012-05-01 |
| JP2009048156A (en) | 2009-03-05 |
| TW200846179A (en) | 2008-12-01 |
| KR100945656B1 (en) | 2010-03-04 |
| KR20090091246A (en) | 2009-08-26 |
| CN101600977A (en) | 2009-12-09 |
| JP4257619B2 (en) | 2009-04-22 |
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