WO2012011325A1 - Film polyester laminé - Google Patents

Film polyester laminé Download PDF

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Publication number
WO2012011325A1
WO2012011325A1 PCT/JP2011/062918 JP2011062918W WO2012011325A1 WO 2012011325 A1 WO2012011325 A1 WO 2012011325A1 JP 2011062918 W JP2011062918 W JP 2011062918W WO 2012011325 A1 WO2012011325 A1 WO 2012011325A1
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WO
WIPO (PCT)
Prior art keywords
film
polyester film
coating layer
acid
polyester
Prior art date
Application number
PCT/JP2011/062918
Other languages
English (en)
Japanese (ja)
Inventor
川崎泰史
藤田真人
Original Assignee
三菱樹脂株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2010165722A external-priority patent/JP5608005B2/ja
Priority claimed from JP2010238517A external-priority patent/JP5570389B2/ja
Application filed by 三菱樹脂株式会社 filed Critical 三菱樹脂株式会社
Publication of WO2012011325A1 publication Critical patent/WO2012011325A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/22—Absorbing filters
    • G02B5/223—Absorbing filters containing organic substances, e.g. dyes, inks or pigments
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
    • 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
    • B32B2255/00—Coating on the layer surface
    • B32B2255/10—Coating on the layer surface on synthetic resin layer or on natural or synthetic rubber layer
    • 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
    • B32B2255/00—Coating on the layer surface
    • B32B2255/26—Polymeric coating
    • 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
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/02—Synthetic macromolecular particles
    • B32B2264/0214—Particles made of materials belonging to B32B27/00
    • 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
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/02—Synthetic macromolecular particles
    • B32B2264/0214—Particles made of materials belonging to B32B27/00
    • B32B2264/0228—Vinyl resin particles, e.g. polyvinyl acetate, polyvinyl alcohol polymers or ethylene-vinyl acetate copolymers
    • B32B2264/0235—Aromatic vinyl resin, e.g. styrenic (co)polymers
    • 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
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/02—Synthetic macromolecular particles
    • B32B2264/0214—Particles made of materials belonging to B32B27/00
    • B32B2264/025—Acrylic resin particles, e.g. polymethyl methacrylate or ethylene-acrylate copolymers
    • 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
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/10—Inorganic particles
    • 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
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/10—Inorganic particles
    • B32B2264/101—Glass
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/416—Reflective
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/42—Polarizing, birefringent, filtering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/514—Oriented
    • B32B2307/518—Oriented bi-axially
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/732—Dimensional properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/20—Displays, e.g. liquid crystal displays, plasma displays
    • B32B2457/202—LCD, i.e. liquid crystal displays

Definitions

  • the present invention relates to a laminated polyester film, and more particularly to a laminated polyester film suitably used as a member for protecting a polarizing plate used in a liquid crystal display.
  • liquid crystal displays have been widely used as display devices for televisions, personal computers, digital cameras, mobile phones and the like.
  • the liquid crystal display has a front-side polarizing plate // liquid crystal // rear-side polarizing plate, where the display side is the front side and the opposite side (backlight side) is the rear side.
  • the polarizing plate usually has a configuration in which a protective film or the like is bonded to a polarizing film of a polyvinyl alcohol film that is uniaxially stretched (protective film / polarizing film / protective film).
  • the protective films disposed on the front and rear surfaces of the polarizing film constituting the front polarizing plate are designated as protective film A and protective film B, respectively, and the protective films disposed on the front and rear surfaces of the polarizing film constituting the rear polarizing plate.
  • the film is a protective film C and a protective film D, respectively
  • the overall configuration is as follows: from the front side, protective film A / front side polarizing film / protective film B // liquid crystal // protective film C / rear side polarizing film / protective Film D is obtained.
  • Various adhesives are applied between the protective films and the polarizing films.
  • a triacetyl cellulose film (hereinafter sometimes abbreviated as a TAC film) is often used because it has high transparency and optical isotropy.
  • TAC film triacetyl cellulose film
  • it is inferior in dimensional stability and heat-and-moisture resistance, and has the disadvantage that the surface must be saponified beforehand with an alkaline solution in order to adhere to the polarizing film.
  • Patent Documents 1 and 2 materials other than TAC film such as norbornene-based film have been studied.
  • a film made of another material does not use a general-purpose resin, there is a problem that the cost is high.
  • the method of using the polyester film which is general purpose resin which can ensure dimensional stability does not require the process of the alkali treatment which has various problems, and also has no problem also in cost is also proposed.
  • the present invention has been made in view of the above circumstances, and the problem to be solved is that it can solve various problems when using a TAC film, and has good adhesiveness with an adhesive, Another object is to provide a laminated polyester film that has a high total light transmittance and can be suitably used as a protective film for a polarizing film, particularly as a protective film on the rear side of the rear polarizing plate (the above-mentioned protective film D).
  • the first gist of the present invention is that a polyester film has a coating layer formed from a coating solution containing polyvinyl alcohol and an isocyanate compound on one surface, and has an absolute reflectance on the other surface.
  • the laminated polyester film has one minimum value in a wavelength range of 300 to 800 nm and has a coating layer having the minimum value of 3.5% or less.
  • the 2nd summary of this invention has an application layer formed from the coating liquid containing polyvinyl alcohol and a carbodiimide type compound in one side of a polyester film, and absolute reflectance is in the other side.
  • the laminated polyester film has one minimum value in a wavelength range of 300 to 800 nm and has a coating layer having the minimum value of 3.5% or less.
  • the adhesive strength with various adhesives for adhering the polarizing film is good, and A laminated polyester film having excellent total light transmittance after forming the polarizing plate is provided.
  • the polyester film constituting the laminated polyester film in the present invention may have a single layer structure or a multilayer structure, and may have four or more layers as long as it does not exceed the gist of the present invention other than a two-layer or three-layer structure. It may be a multilayer, and is not particularly limited.
  • the polyester used in the present invention may be a homopolyester or a copolyester.
  • a homopolyester those obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol are preferred.
  • the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid
  • examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol.
  • Typical polyester includes polyethylene terephthalate and the like.
  • examples of the dicarboxylic acid component of the copolyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (for example, p-oxybenzoic acid).
  • examples of the glycol component include one or more types such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 4-cyclohexanedimethanol, neopentyl glycol and the like.
  • an ultraviolet absorber can be contained in order to prevent the liquid crystal of the liquid crystal display from being deteriorated by ultraviolet rays.
  • the ultraviolet absorber is not particularly limited as long as it is a compound having ultraviolet absorbing ability and can withstand the heat applied in the production process of the polyester film.
  • an organic ultraviolet absorber there are an organic ultraviolet absorber and an inorganic ultraviolet absorber, and an organic ultraviolet absorber is preferable from the viewpoint of transparency.
  • an organic type ultraviolet absorber For example, a benzotriazole type, a cyclic imino ester type, a benzophenone type etc. are mentioned. From the viewpoint of durability, benzotriazole and cyclic imino ester are more preferable. It is also possible to use two or more ultraviolet absorbers in combination.
  • the benzotriazole-based ultraviolet absorber is not limited to the following, and examples thereof include 2- [2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl] -2H-benzotriazole, 2- [2 '-Hydroxy-5'-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2- [2'- Hydroxy-5 '-(methacryloyloxyhexyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-3'-tert-butyl-5'-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2 -[2'-hydroxy-5'-tert-butyl-3 '-(methac Royloxyethyl)
  • the cyclic imino ester-based ultraviolet absorber is not limited to the following, and examples thereof include 2-methyl-3,1-benzoxazin-4-one and 2-butyl-3,1-benzoxazine-4. -One, 2-phenyl-3,1-benzoxazin-4-one, 2- (1- or 2-naphthyl) -3,1-benzoxazin-4-one, 2- (4-biphenyl) -3, 1-benzoxazin-4-one, 2-p-nitrophenyl-3,1-benzoxazin-4-one, 2-m-nitrophenyl-3,1-benzoxazin-4-one, 2-p-benzoyl Phenyl-3,1-benzoxazin-4-one, 2-p-methoxyphenyl-3,1-benzoxazin-4-one, 2-o-methoxyphenyl-3,1-benzoxazin-4-one 2-cyclohexyl-3,1-benzoxazin-4-one, 2-
  • a benzoxazinone-based compound which is difficult to be yellowed is preferably used.
  • a compound represented by the following general formula (1) is more preferably used. It is done.
  • R represents a divalent aromatic hydrocarbon group
  • X 1 and X 2 are each independently selected from hydrogen or the following functional group group, but are not necessarily limited thereto.
  • 2,2 ′-(1,4-phenylene) bis [4H-3,1-benzoxazin-4-one] is particularly preferable in the present invention.
  • the amount of the ultraviolet absorber contained in the laminated polyester film of the present invention is usually 10.0% by weight or less, preferably 0.3 to 3.0% by weight.
  • the ultraviolet absorber may bleed out on the surface, which may cause deterioration of surface functionality such as adhesion deterioration.
  • the ultraviolet absorber is preferably blended in the intermediate layer.
  • the compound can be prevented from bleeding out to the film surface, and as a result, properties such as film adhesion can be maintained.
  • the light transmittance at a wavelength of 380 nm is preferably 10% or less, more preferably. Is 5% or less.
  • the light transmittance at a wavelength of 380 nm can be adjusted by changing the type and amount of the above-described ultraviolet absorber.
  • the polyester layer of the film of the present invention it is preferable to blend particles for the main purpose of imparting slipperiness and preventing scratches in each step.
  • the kind of the particle to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness.
  • Specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and phosphoric acid.
  • examples include inorganic particles such as magnesium, kaolin, aluminum oxide, and titanium oxide, and organic particles such as acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin, and benzoguanamine resin.
  • precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process can also be used.
  • the shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction
  • the average particle size of the particles used is usually in the range of 0.01 to 5 ⁇ m, preferably 0.1 to 3 ⁇ m. If the average particle size is less than 0.01 ⁇ m, the slipperiness may not be sufficiently imparted, or the particles may be aggregated to make the dispersibility insufficient, thereby reducing the transparency of the film. On the other hand, when the thickness exceeds 5 ⁇ m, the surface roughness of the film becomes too rough, and a defect may occur in a subsequent process.
  • the particle content in the polyester layer is usually in the range of 0.0001 to 5% by weight, preferably 0.0003 to 3% by weight.
  • the particle content is less than 0.0001% by weight, the slipperiness of the film may be insufficient.
  • the content exceeds 5% by weight, the transparency of the film is insufficient. There is a case.
  • the method for adding particles to the polyester layer is not particularly limited, and a conventionally known method can be adopted.
  • it can be added at any stage for producing the polyester constituting each layer, but it is preferably added after completion of esterification or transesterification.
  • a method of blending a slurry of particles dispersed in ethylene glycol or water with a vented kneading extruder and a polyester raw material, or a blending of dried particles and a polyester raw material using a kneading extruder is done by methods.
  • antioxidants In addition to the above-mentioned particles, conventionally known antioxidants, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film in the present invention as necessary.
  • the thickness of the polyester film in the present invention is not particularly limited as long as it can be formed as a film, but is usually 10 to 200 ⁇ m, preferably 25 to 50 ⁇ m.
  • a production example of the polyester film in the present invention will be specifically described, but is not limited to the following production examples. That is, a method of using the polyester raw material described above and cooling and solidifying a molten sheet extruded from a die with a cooling roll to obtain an unstretched sheet is preferable. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method or a liquid application adhesion method is preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine.
  • the stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7.0 times, preferably 3.0 to 6.0 times.
  • the film is stretched in the direction perpendicular to the first stretching direction.
  • the stretching temperature is usually 70 to 170 ° C.
  • the stretching ratio is usually 3.0 to 7.0 times, preferably 3.5 to 6 times. .0 times.
  • heat treatment is performed at a temperature of 180 to 270 ° C. under tension or relaxation within 30% to obtain a biaxially oriented film.
  • a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.
  • the simultaneous biaxial stretching method can be adopted for the production of the polyester film constituting the laminated polyester film.
  • the simultaneous biaxial stretching method is a method in which the above-mentioned unstretched sheet is stretched and oriented simultaneously in the machine direction and the width direction in a state where the temperature is usually controlled at 70 to 120 ° C., preferably 80 to 110 ° C. Is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area magnification. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a stretched oriented film.
  • a conventionally known stretching method such as a screw method, a pantograph method, or a linear driving method can be employed.
  • the coating layer constituting the laminated polyester film in the present invention
  • it may be provided by in-line coating which treats the film surface during the process of forming a polyester film, or offline coating which is applied outside the system on a once produced film may be adopted. Since the coating can be performed simultaneously with the film formation, the production can be handled at a low cost, and therefore in-line coating is preferably used.
  • the in-line coating is not limited to the following, for example, in the sequential biaxial stretching, a coating treatment can be performed particularly before the lateral stretching after the longitudinal stretching is finished.
  • a coating treatment can be performed particularly before the lateral stretching after the longitudinal stretching is finished.
  • the coating layer is provided on the polyester film by in-line coating, it is possible to apply at the same time as the film formation, and the coating layer can be processed at a high temperature in the heat treatment process of the polyester film after stretching. Performances such as adhesion to various surface functional layers that can be formed on the layer and heat-and-moisture resistance can be improved.
  • the thickness of an application layer can also be changed with a draw ratio, and compared with offline coating, thin film coating can be performed more easily. That is, a film suitable as a polyester film can be produced by in-line coating, particularly coating before stretching.
  • a coating layer (hereinafter sometimes abbreviated as a first coating layer) formed from a coating solution containing polyvinyl alcohol and an isocyanate compound or a carbodiimide compound.
  • a coating layer (hereinafter referred to as second coating layer) having an absolute reflectance of one minimum value in the wavelength range of 300 to 800 nm and the minimum value of 3.5% or less. It may be abbreviated to be an essential requirement.
  • the first coating layer in the present invention is a coating layer for improving adhesiveness with various functional layers, for example, various adhesives used for laminating the polarizing film and the laminated polyester film of the present invention. Can be used to improve the adhesion.
  • the inventors of the present invention have studied polyester resins for improving the adhesion to the polyester film and polyvinyl alcohol for improving the adhesion to the adhesive layer. There was no adhesion. Moreover, although the coating layer by the combination of a polyester resin and polyvinyl alcohol was also examined, the big improvement in adhesiveness was not seen. Furthermore, when examining combinations of various materials, it was possible to improve adhesion by combining polyvinyl alcohol with isocyanate compounds or carbodiimide compounds, and by devising the composition ratio, and as an adhesive for polarizing film protection. A successful coating layer was successfully formed. Furthermore, it has also been found that the adhesiveness is greatly improved by combining a polyester resin.
  • the polyvinyl alcohol contained in the coating solution used for forming the first coating layer has a polyvinyl alcohol moiety, and includes, for example, modified compounds partially acetalized or butyralized with respect to polyvinyl alcohol.
  • Conventionally known polyvinyl alcohol can be used.
  • the degree of polymerization of polyvinyl alcohol is not particularly limited, but is usually 100 or more, preferably 300 to 40,000. When the degree of polymerization is less than 100, the water resistance of the coating layer may decrease.
  • the saponification degree of polyvinyl alcohol is not particularly limited, but a polyvinyl acetate saponified product in a range of 70 mol% or more, preferably in the range of 70 to 99.9 mol% is practically used.
  • the isocyanate compound contained in the coating solution used for forming the first coating layer is a compound having an isocyanate derivative structure typified by isocyanate or blocked isocyanate.
  • isocyanates include aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate, and aromatic rings such as ⁇ , ⁇ , ⁇ ′, ⁇ ′-tetramethylxylylene diisocyanate.
  • Aliphatic isocyanates such as aliphatic isocyanate, methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylene bis (4-cyclohexyl isocyanate), isopropylidene dicyclohexyl diisocyanate
  • Alicyclic isocyanates such as bets are exemplified.
  • polymers and derivatives such as burettes, isocyanurates, uretdiones, and carbodiimide modified products of these isocyanates are also included. These may be used alone or in combination.
  • isocyanates aliphatic isocyanates or alicyclic isocyanates are more preferable than aromatic isocyanates in order to avoid yellowing due to ultraviolet rays.
  • the blocking agent When used in the state of blocked isocyanate, the blocking agent includes, for example, bisulfites, phenolic compounds such as phenol, cresol, and ethylphenol, and alcohols such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol, and ethanol.
  • active methylene compounds such as dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate and acetylacetone, mercaptan compounds such as butyl mercaptan and dodecyl mercaptan, lactam compounds such as ⁇ -caprolactam and ⁇ -valerolactam , Amine compounds such as diphenylaniline, aniline, ethyleneimine, acetanilide, acid amide compounds of acetic acid amide, formaldehyde, acetal Examples include oxime compounds such as dooxime, acetone oxime, methyl ethyl ketone oxime, and cyclohexanone oxime, and these may be used alone or in combination of two or more.
  • the isocyanate compound in the present invention may be used alone or as a mixture or combination with various polymers. In the sense of improving the dispersibility and crosslinkability of the isocyanate compound, it is preferable to use a mixture or a bond with a polyester resin or a urethane resin.
  • the carbodiimide-based compound contained in the coating liquid used for forming the first coating layer is a compound having a carbodiimide structure, and has adhesion to a surface functional layer such as a hard coat layer that can be formed on the coating layer. It is used for improvement and improvement of moisture and heat resistance of the coating layer.
  • a carbodiimide compound is a compound having one or more carbodiimide structures in the molecule, but a polycarbodiimide compound having two or more in the molecule is more preferable for better adhesion and the like.
  • the carbodiimide compound can be synthesized by a conventionally known technique, and generally a condensation reaction of a diisocyanate compound is used.
  • the diisocyanate compound is not particularly limited, and any of aromatic and aliphatic compounds can be used.
  • tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexa examples include methylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, and dicyclohexylmethane diisocyanate.
  • polyester resin in combination with the first coating layer of the present invention in order to improve adhesion.
  • the polyester resin that can be contained in the coating liquid used for forming the first coating layer includes, for example, the following polyvalent carboxylic acid and polyvalent hydroxy compound as main constituent components. That is, as the polyvalent carboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and 2,6 -Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid , Trimellitic anhydride, pyromellitic anhydride, phthalic anhydride, p-hydroxybenz
  • One or more compounds may be appropriately selected from these compounds, and a polyester resin may be synthesized by a conventional polycondensation reaction.
  • a hydrophilic functional group is contained in the polyester resin.
  • the hydrophilic functional group include a carboxylic acid group and a sulfonic acid group.
  • a dispersion with a carboxylic acid group is preferable in terms of improving adhesiveness.
  • the ratio of each component in the coating solution forming the first coating layer of the film of the present invention is as described in the following (1) and (2).
  • the polyvinyl alcohol is usually 10 to 80% by weight, preferably 15 to 60% by weight, more preferably 20 to 50% as a proportion of all nonvolatile components in the coating solution.
  • the amount by weight of the isocyanate compound is usually 10 to 80% by weight, preferably 15 to 60% by weight, more preferably 20 to 40% by weight.
  • the weight ratio of the solid content of polyvinyl alcohol: isocyanate compound is usually 1.0 to 8.0: 1.0 to 8.0, preferably 1.0 to 4.0: 1.0 to 4.0. More preferably, it is in the range of 1.0 to 2.5: 1.0 to 2.5.
  • the proportion is preferably 80% by weight or less, more preferably 15 to 65% by weight, and still more preferably 20 to 40% by weight.
  • polyvinyl alcohol is usually 10 to 80% by weight, preferably 15 to 60% by weight, more preferably 20 to 45% as a ratio to the total nonvolatile components in the coating solution.
  • the weight percentage of the carbodiimide compound is usually 10 to 80 weight%, preferably 15 to 60 weight%, more preferably 25 to 45 weight%.
  • the weight ratio of the solid content of the polyvinyl alcohol: carbodiimide compound is usually 1.0 to 8.0: 1.0 to 8.0, preferably 1.0 to 4.0: 1.0 to 4.0. More preferably, it is in the range of 1.0 to 1.8: 1.0 to 2.3.
  • the proportion is preferably 80% by weight or less, more preferably 15 to 65% by weight, and still more preferably 20 to 50% by weight.
  • the adhesiveness with the adhesive layer may not be sufficient due to the small amount of the polyvinyl alcohol component.
  • it exceeds there are cases where the adhesion to the polyester film is not sufficient due to the small amount of other components.
  • the coating layer may become brittle due to a small amount of crosslinking components, and the heat and humidity resistance may be reduced. Due to the small amount of components, the adhesion to the polyester film and the adhesion to the adhesive layer may not be sufficient.
  • a polymer other than polyvinyl alcohol or polyester resin can be used in combination in order to improve the coating surface state and transparency.
  • polymer examples include acrylic resin, urethane resin, polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, and starches.
  • a crosslinking agent other than an isocyanate compound or a carbodiimide compound can be used in combination in the first coating layer as long as the gist of the present invention is not impaired.
  • Various known compounds can be used as the crosslinking agent, and examples thereof include an oxazoline compound, a melamine compound, and an epoxy compound.
  • An oxazoline compound is a compound having an oxazoline group in the molecule.
  • a polymer containing an oxazoline group is preferable, and it can be prepared by polymerization of an addition polymerizable oxazoline group-containing monomer alone or with another monomer.
  • Addition-polymerizable oxazoline group-containing monomers include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, Examples thereof include 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, and the like, and one or a mixture of two or more thereof can be used. Of these, 2-isopropenyl-2-oxazoline is preferred because it is easily available industrially.
  • the other monomer is not particularly limited as long as it is a monomer copolymerizable with an addition polymerizable oxazoline group-containing monomer.
  • alkyl (meth) acrylate (alkyl groups include methyl, ethyl, n-propyl, isopropyl, (Meth) acrylic acid esters such as n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group); acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrene
  • Unsaturated carboxylic acids such as sulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); Unsaturated nitriles such as acrylonitrile, methacrylonitrile; (meth) acrylamide, N-alky
  • the melamine compound is a compound having a melamine skeleton in the compound.
  • an alkylolated melamine derivative a compound partially or completely etherified by reacting an alcohol with an alkylolated melamine derivative, and a mixture thereof can be used.
  • alcohol used for etherification methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like are preferably used.
  • a melamine compound either a monomer or a multimer more than a dimer may be sufficient, or a mixture thereof may be used.
  • a product obtained by co-condensing urea or the like with a part of melamine can be used, and a catalyst can be used to increase the reactivity of the melamine compound.
  • An epoxy compound is a compound having an epoxy group in the molecule.
  • Examples include condensates of epichlorohydrin with hydroxyl groups and amino groups such as ethylene glycol, polyethylene glycol, glycerin, polyglycerin, and bisphenol A, and polyepoxy compounds, diepoxy compounds, monoepoxy compounds, glycidylamine compounds, and the like. is there.
  • polyepoxy compound examples include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, trimethylolpropane.
  • polyglycidyl ether and diepoxy compound examples include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and propylene glycol diglycidyl ether.
  • Polypropylene glycol diglycidyl ether polypropylene glycol diglycidyl ether, poly Examples of tetramethylene glycol diglycidyl ether and monoepoxy compounds include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and glycidyl amine compounds such as N, N, N ′, N ′,-tetraglycidyl-m-. Examples include xylylenediamine and 1,3-bis (N, N-diglycidylamino) cyclohexane.
  • cross-linking agents are preferably water-soluble or water-dispersible in consideration of application to in-line coating.
  • the first coating layer preferably contains particles for the purpose of improving the blocking property and slipperiness of the coating layer, and the average particle size is preferably in the range of 1 ⁇ m or less from the viewpoint of the transparency of the film. Is 0.7 ⁇ m or less, more preferably 0.2 ⁇ m or less. From the viewpoint of blocking properties and slipperiness, the average particle size is preferably in the range of 0.01 ⁇ m or more, more preferably in the range of 0.03 ⁇ m or more, and still more preferably in the range of 0.05 ⁇ m or more.
  • the particles include silica, alumina, kaolin, calcium carbonate, titanium oxide, and organic particles. Among them, silica is particularly preferable.
  • the content of the particles in the coating layer depends on the average particle diameter, but is preferably in the range of 0.1 to 30% by weight, more preferably in the range of 0.5 to 10% by weight, and still more preferably 1 to 6%. It is in the range of wt%.
  • the second coating layer in the present invention has a low reflectance design, and when used as a protective film on the rear surface side of the rear surface side polarizing plate, it can improve the total light transmittance when the polarizing plate is used. It is a coating layer.
  • the total light transmittance of the laminated polyester film is based on the optical characteristics of the polyester film, the first coating layer, and the second coating layer. Since the characteristic does not greatly contribute to the total light transmittance of the entire polarizing plate, the most important optical characteristic is the side not bonded to the polarizing film, that is, the second coating layer side.
  • the total light transmittance of the laminated polyester film there is also an influence of the first coating layer, so it cannot be accurately discussed, but in general, it is 90.0% or more, preferably 90.5% or more, more preferably It is 91.0% or more.
  • the second coating layer has one local minimum value in the wavelength range of 300 to 800 nm, and the minimum value is It is essential that it is 3.5% or less. More preferable conditions for the minimum wavelength are in the range of 400 to 700 nm, and more preferably in the range of 450 to 650 nm. The minimum value is preferably 3.0% or less, and more preferably 2.5% or less.
  • the total light transmittance is reduced when the polarizing plate is used, thereby lowering the luminance of the polarizing plate, resulting in a liquid crystal display.
  • the screen becomes darker.
  • Acrylic resin and urethane resin generally have a low refractive index, so that they are suitable for achieving the absolute reflectance as described above, that is, for increasing the total light transmittance when a polarizing plate is used.
  • the material is effective for forming the second coating layer in the present invention. Further, the total light transmittance can be more effectively improved by controlling the film thickness within the range of 0.04 to 0.15 ⁇ m.
  • An acrylic resin is a polymer composed of a polymerizable monomer having a carbon-carbon double bond, as typified by acrylic and methacrylic monomers. These may be either a homopolymer or a copolymer. Moreover, the copolymer of these polymers and other polymers (for example, polyester, polyurethane, etc.) is also included. For example, a block copolymer or a graft copolymer. Alternatively, a polymer (possibly a mixture of polymers) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyester solution or a polyester dispersion is also included.
  • a polymer (in some cases, a mixture of polymers) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyurethane solution or polyurethane dispersion is also included.
  • a polymer (in some cases, a polymer mixture) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in another polymer solution or dispersion is also included.
  • a fluorine atom-containing compound having a low refractive index In order to improve the total light transmittance more efficiently, it is also possible to use a fluorine atom-containing compound having a low refractive index.
  • the polymerizable monomer having a carbon-carbon double bond is not particularly limited, but particularly representative compounds include, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, citracone Various carboxyl group-containing monomers such as acids, and salts thereof; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monobutyl hydroxyl fumarate, Various hydroxyl group-containing monomers such as monobutylhydroxy itaconate; various monomers such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate ( (Meth) acrylic acid esters Various nitrogen-containing compounds such as (meth) acrylamide, diacetone acrylamide, N-methylol acrylamide
  • Urethane resin is a polymer compound having urethane resin in the molecule.
  • urethane resin is prepared by reaction of polyol and isocyanate.
  • the polyol include polycarbonate polyols, polyester polyols, polyether polyols, polyolefin polyols, and acrylic polyols. These compounds may be used alone or in combination.
  • Polycarbonate polyols are obtained from a polyhydric alcohol and a carbonate compound by a dealcoholization reaction.
  • Polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentane Diol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decane Examples thereof include diol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 3,3-dimethylol heptane.
  • Examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and ethylene carbonate.
  • Examples of the polycarbonate-based polyols obtained from these reactions include poly (1,6-hexylene) carbonate, poly (3- And methyl-1,5-pentylene) carbonate.
  • Polyester polyols include polycarboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or their acid anhydrides.
  • polycarboxylic acids malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.
  • polyhydric alcohol ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol 2-methyl-2-propyl- , 3-propanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexane Diol, 1,9-nonanediol
  • polyether polyols examples include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol and the like.
  • polyisocyanate compound used for obtaining the urethane resin examples include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate, ⁇ , ⁇ , ⁇ ′, ⁇ ′.
  • aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate, ⁇ , ⁇ , ⁇ ′, ⁇ ′.
  • -Aliphatic diisocyanates having aromatic rings such as tetramethylxylylene diisocyanate, aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl Methanzi Isocyanate, alicyclic diisocyanates such as isopropylidene dicyclohexyl diisocyanates. These may be used alone or in combination.
  • a chain extender may be used when synthesizing the urethane resin, and the chain extender is not particularly limited as long as it has two or more active groups that react with an isocyanate group. Alternatively, a chain extender having two amino groups can be mainly used.
  • chain extender having two hydroxyl groups examples include aliphatic glycols such as ethylene glycol, propylene glycol and butanediol, aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene, and esters such as neopentyl glycol hydroxypivalate. And glycols such as glycols.
  • chain extender having two amino groups examples include aromatic diamines such as tolylenediamine, xylylenediamine, diphenylmethanediamine, ethylenediamine, propylenediamine, hexanediamine, 2,2-dimethyl-1,3- Propanediamine, 2-methyl-1,5-pentanediamine, trimethylhexanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10- Aliphatic diamines such as decane diamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethanediamine, isopropylidine cyclohexyl-4,4′-diamine, 1,4-diaminocyclohexane, 1 , 3-Bisaminomethylcyclohexane Alicyclic diamines, and the like of.
  • the urethane resin used in the present invention may use a solvent as a medium, but preferably uses water as a medium.
  • a forced emulsification type using an emulsifier there are a forced emulsification type using an emulsifier, a self-emulsification type in which a hydrophilic group is introduced into the urethane resin, and a water-soluble type.
  • a self-emulsification type in which an ionic group is introduced into the skeleton of a urethane resin to form an ionomer is preferable because of excellent storage stability of the liquid and water resistance, transparency, and adhesion of the resulting coating layer.
  • Examples of the ionic group to be introduced include various groups such as a carboxyl group, sulfonic acid, phosphoric acid, phosphonic acid, quaternary ammonium salt, and the like, and a carboxyl group is preferable.
  • a method for introducing a carboxyl group into a urethane resin various methods can be taken in each stage of the polymerization reaction. For example, there are a method of using a carboxyl group-containing resin as a copolymer component during prepolymer synthesis, and a method of using a component having a carboxyl group as one component such as polyol, polyisocyanate, and chain extender. In particular, a method in which a desired amount of carboxyl groups is introduced using a carboxyl group-containing diol depending on the amount of this component charged is preferred.
  • dimethylolpropionic acid, dimethylolbutanoic acid, bis- (2-hydroxyethyl) propionic acid, bis- (2-hydroxyethyl) butanoic acid, and the like are copolymerized with a diol used for polymerization of a urethane resin.
  • the carboxyl group is preferably in the form of a salt neutralized with ammonia, amine, alkali metal, inorganic alkali or the like. Particularly preferred are ammonia, trimethylamine and triethylamine.
  • a carboxyl group from which the neutralizing agent has been removed in the drying step after coating can be used as a crosslinking reaction point by another crosslinking agent.
  • another crosslinking agent it is possible to further improve the durability, solvent resistance, water resistance, blocking resistance, and the like of the obtained coating layer, as well as excellent stability in a liquid state before coating.
  • the content of the acrylic resin or the urethane resin in the second coating layer cannot be unconditionally discussed because it depends on the refractive index of the acrylic resin or the urethane resin, but preferably 40% by weight or more. More preferably, it is the range of 50 weight% or more, More preferably, it is the range of 60 weight% or more. If it is less than 40% by weight, the total light transmittance may not be sufficiently improved.
  • a polymer other than an acrylic resin or a urethane resin can be used in combination in order to improve the coating surface shape and transparency.
  • the polymer used in combination it is preferable not to use many polymers having a high refractive index in consideration of the influence on the total light transmittance.
  • polymer examples include polyester resin, polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, starches and the like.
  • a crosslinking agent can be used in the second coating layer as long as the gist of the present invention is not impaired.
  • a cross-linking agent By using a cross-linking agent, the coating layer becomes strong, so that the heat and moisture resistance and the scratch resistance may be further improved.
  • the crosslinking agent include melamine compounds, epoxy compounds, oxazoline compounds, isocyanate compounds, carbodiimide compounds, and the like. These cross-linking agents may be used alone or in combination of two or more.
  • the second coating layer may contain particles for the purpose of improving the blocking property and slipperiness of the coating layer, and the same particles as those used in the first coating layer can be used.
  • the first coating layer and the second coating layer have an antifoaming agent, coating property improving agent, thickening agent, organic lubricant, antistatic agent, ultraviolet absorption as necessary. Agents, antioxidants, foaming agents, dyes, pigments and the like may be contained.
  • Analysis of various components in the coating layer can be performed by surface analysis such as TOF-SIMS.
  • a coating layer When providing a coating layer by in-line coating, apply the above-mentioned series of compounds as an aqueous solution or water dispersion on a polyester film with a coating solution adjusted to a solid content concentration of about 0.1 to 50% by weight. It is preferable to produce a laminated polyester film. Moreover, in the range which does not impair the main point of this invention, a small amount of organic solvents may be contained in the coating liquid for the purpose of improving dispersibility in water, improving film-forming properties, and the like. Only one type of organic solvent may be used, or two or more types may be used as appropriate.
  • the thickness of the first coating layer of the laminated polyester film in the present invention is usually in the range of 0.002 to 1.0 ⁇ m, more preferably 0.03 to 0.5 ⁇ m, and further preferably 0.04 to 0.2 ⁇ m. . If the film thickness is less than 0.002 ⁇ m, sufficient adhesion may not be obtained, and if it exceeds 1.0 ⁇ m, the appearance, transparency, and film blocking properties may be deteriorated.
  • the thickness of the second coating layer of the laminated polyester film is usually in the range of 0.04 to 0.15 ⁇ m, more preferably in the range of 0.06 to 0.13 ⁇ m. Since it depends on the refractive index of the coating layer, it cannot be said unconditionally. However, when the film thickness is out of this range, a high total light transmittance may not be obtained when a polarizing plate is used.
  • a conventionally known coating method such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating or the like can be used.
  • the drying and curing conditions for forming the coating layer on the polyester film are not particularly limited.
  • the coating layer is provided by off-line coating, it is usually 3 to 40 at 80 to 200 ° C.
  • the heat treatment should be performed for a second, preferably 100 to 180 ° C. for 3 to 40 seconds.
  • the coating layer is provided by in-line coating, it is usually preferable to perform heat treatment at 70 to 280 ° C. for 3 to 200 seconds as a guide.
  • polyester film constituting the laminated polyester film in the present invention may be subjected to surface treatment such as corona treatment or plasma treatment in advance.
  • the laminated polyester film of the present invention is used as, for example, a protective film for a polarizing film in a polarizing plate, generally, the polarizing film is bonded to the first coating layer side through an adhesive for adhering the polarizing film.
  • the adhesive conventionally known ones can be used, for example, acrylic compounds such as polyvinyl alcohol, polyvinyl butyral and polybutyl acrylate, and epoxy having an alicyclic epoxy group exemplified by glycidyl group and epoxycyclohexane. System compounds and the like.
  • polyvinyl alcohol which is uniaxially stretched and dyed with iodine or the like is laminated on the prepared adhesive layer as a polarizing film.
  • a protective film, a retardation film, or the like can be bonded to the opposite side of the polarizing film to form a polarizing plate. That is, when the laminated polyester film of the present invention is used for a polarizing plate, the layer configuration exemplified above is protective film / polarizing film / adhesive / first coating layer / polyester film / second coating layer.
  • Coating layer thickness measurement method The surface of the coating layer was dyed with RuO 4 and embedded in an epoxy resin. Thereafter, the section prepared by the ultrathin section method was stained with RuO 4 , and the cross section of the coating layer was measured using TEM (H-7650 manufactured by Hitachi, acceleration voltage 100 V).
  • Adhesive evaluation method An adhesive layer was formed by applying and drying a 5% by weight aqueous solution of polyvinyl alcohol having a polymerization degree of 1000 and a saponification degree of 98.5 mol% on the first coated layer surface of the laminated polyester film so that the dry film thickness was 2 ⁇ m. .
  • a 18 mm wide tape (Cellotape (registered trademark), Elpac (registered trademark) LP-18, manufactured by Nichiban Co., Ltd.) was affixed on this adhesive layer, peeled off rapidly at a peeling angle of 180 degrees, and then peeled off. The surface was observed. If the peeled area was 5% or less, ⁇ if over 5% and 20% or less, ⁇ , if over 20% and 50% or less, ⁇ , if over 50%, x.
  • a black tape (vinyl tape VT-50 manufactured by Nichiban Co., Ltd.) is pasted on the measurement film back surface (first coated layer surface) of the polyester film in advance, and a spectrophotometer (UV-visible spectrophotometer V-570 manufactured by JASCO Corporation) and automatic absolute Using the reflectance measuring device AMR-500N), the wavelength of the coating layer surface is synchronized mode, incident angle 5 °, N polarization, response fast, data collection interval 1.0 nm, bandwidth 10 nm, scanning speed 1000 m / min. Absolute reflectance in the range of 300 to 800 nm was measured, and the wavelength (bottom wavelength) and absolute reflectance at the minimum value were evaluated.
  • Evaluation method of total light transmittance when a polarizing plate is used A 5% by weight aqueous solution of polyvinyl alcohol having a polymerization degree of 1000 and a saponification degree of 98.5 mol% is applied to the first coating layer side of the laminated polyester film, and a polarizing film of polyvinyl alcohol-iodine is bonded using a roll machine. The polarizing plate was dried at 70 ° C. for 4 minutes. On the other hand, as a reference, a polarizing plate was prepared in the same manner for a triacetyl cellulose film (TAC film).
  • TAC film triacetyl cellulose film
  • the total light transmittance was measured according to JIS K 7361 using a haze meter HM-150 manufactured by Murakami Color Research Laboratory, and the total light transmittance of the polarizing plate formed from the laminated polyester film was evaluated. did. That is, compared with the total light transmittance of the polarizing plate formed from the TAC film, when the reduction amount is 1% or less, the case where the reduction amount exceeds 1% and there is a concern about the reduction of the brightness. It was.
  • the polyester used in the examples and comparative examples was prepared as follows. ⁇ Method for producing polyester (A)> Using 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol as starting materials, 0.09 parts by weight of magnesium acetate tetrahydrate as a catalyst is placed in the reactor, the reaction start temperature is set to 150 ° C., and the methanol is distilled off gradually. The reaction temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. After adding 0.04 part by weight of ethyl acid phosphate to this reaction mixture, 0.04 part by weight of antimony trioxide was added, and a polycondensation reaction was carried out for 4 hours.
  • the temperature was gradually raised from 230 ° C. to 280 ° C.
  • the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg.
  • the reaction was stopped at a time corresponding to an intrinsic viscosity of 0.63 due to a change in stirring power of the reaction tank, and the polymer was discharged under nitrogen pressure.
  • the intrinsic viscosity of the obtained polyester (A) was 0.63.
  • polyester (B) ⁇ Method for producing polyester (B)>
  • the method for producing polyester (A) after adding 0.04 part by weight of ethyl acid phosphate, 0.2 part by weight of silica particles dispersed in ethylene glycol having an average particle diameter of 2 ⁇ m and 0.04 part by weight of antimony trioxide And polyester (B) was obtained using the same method as the production method of polyester (A) except that the polycondensation reaction was stopped at the time corresponding to the intrinsic viscosity of 0.65.
  • the obtained polyester (B) had an intrinsic viscosity of 0.65.
  • polyester (C) ⁇ Method for producing polyester (C)>
  • the polyester (A) was subjected to a vented twin screw extruder and 2,2 ′-(1,4-phenylene) bis [4H-3,1-benzoxazin-4-one] (manufactured by CYTEC Co., Ltd.) as an ultraviolet absorber.
  • CYASORB UV-3638 molecular weight 369 benzoxazinone
  • the intrinsic viscosity of the obtained polyester (C) was 0.59.
  • Examples of compounds constituting the coating layer are as follows. (Compound example) ⁇ Polyvinyl alcohol: (I) Polyvinyl alcohol having a saponification degree of 88 mol% and a polymerization degree of 500
  • Isocyanate compounds (IIA) 33.6 parts by weight of hexamethylene diisocyanate was added to 200 parts by weight of a polyester (molecular weight 2000) of bisphenol A ethylene oxide 2 mol adduct and maleic acid, and reacted at 100 ° C. for 2 hours. Next, the blocked isocyanate compound diluted with 718 parts by weight of water after the temperature of the system was once lowered to 50 ° C, 73 parts by weight of a 30% aqueous sodium bisulfite solution was added and stirred at 45 ° C for 60 minutes.
  • Carbodiimide compounds (IIB) Polycarbodiimide compound (“Carbodilite V-02” manufactured by Nisshinbo)
  • Emulsion polymer emulsifier: anionic surfactant
  • Example 1 A mixed raw material obtained by mixing polyester (A) and (B) at a ratio of 90% and 10%, respectively, is used as a raw material for the outermost layer (surface layer), and polyesters (A) and (C) are at a ratio of 85% and 15%, respectively.
  • Each of the mixed raw materials is fed to two extruders as a raw material for the intermediate layer, melted at 285 ° C., and then two types and three layers (surface layer / intermediate layer / The unstretched sheet was obtained by coextrusion and cooling and solidification in the layer structure of (surface layer). Next, the film was stretched 3.4 times in the machine direction at a film temperature of 85 ° C.
  • the coating liquid A1 shown in Table 1 below was applied to one side of the longitudinally stretched film (first coating layer).
  • the coating liquid B1 shown in Table 3 below was applied to the opposite surface (formation of the second coating layer), led to a tenter, stretched 4.3 times at 120 ° C in the transverse direction, and heat-treated at 225 ° C. Thereafter, the polyester is loosened by 2% in the lateral direction and has a thickness of 38 ⁇ m (surface layer: 4 ⁇ m, intermediate layer: 30 ⁇ m) having a first coating layer of 0.05 ⁇ m and a second coating layer of 0.10 ⁇ m (after drying). A film was obtained.
  • the adhesiveness of the first coating layer was good
  • the minimum absolute reflectance of the second coating layer was kept as low as 2.5%
  • the transmittance at 380 nm was 4%. It was confirmed that it absorbs ultraviolet rays.
  • Table 4 The properties of this film are shown in Table 4 below.
  • Example 2-17, 21-37 In Example 1, it manufactured like Example 1 except having changed the coating composition into the coating composition shown in Table 1 and Table 3, and obtained the polyester film.
  • the finished polyester film was as shown in Table 4 or Table 5.
  • Examples 18, 38 A mixed raw material obtained by mixing polyester (A) and (B) at a ratio of 90% and 10%, respectively, is used as a raw material for the outermost layer (surface layer), and polyesters (A) and (C) are at a ratio of 80% and 20%, respectively.
  • a polyester film was obtained in the same manner as in Example 1 except that the mixed raw material was used as a raw material for the intermediate layer.
  • the finished polyester film was as shown in Table 4 or Table 5. Further, the transmittance at 380 nm was 1%, and it was confirmed that ultraviolet rays were absorbed.
  • Examples 19 and 39 A mixed raw material in which polyesters (A) and (B) are mixed at a ratio of 90% and 10%, respectively, is used as a raw material for the outermost layer (surface layer), and polyesters (A) and (C) are respectively at a ratio of 90% and 10%.
  • a polyester film was obtained in the same manner as in Example 1 except that the mixed raw material was used as a raw material for the intermediate layer.
  • the finished polyester film was as shown in Table 4 or Table 5. Further, the transmittance at 380 nm was 9%, and it was confirmed that ultraviolet rays were absorbed.
  • Examples 20, 40 Example 1 except that a mixed raw material in which polyesters (A) and (B) are mixed at a ratio of 90% and 10%, respectively, is used as a raw material for the outermost layer (surface layer) and polyester (A) is used as a raw material for the intermediate layer. In the same manner, a polyester film was obtained. The finished polyester film was as shown in Table 4 or Table 5.
  • Comparative Examples 1 to 15 A polyester film was obtained in the same manner as in Example 1 except that the coating agent composition was changed to the coating agent compositions shown in Tables 1 to 3 in Example 1. When the completed laminated polyester film was evaluated, it was as shown in Table 6, and it was as shown in Table 6 that the adhesiveness was weak, the minimum value of reflectance was not seen, or the minimum value of reflectance was high.
  • the film of the present invention is, for example, a protective film for a polarizing film used for a liquid crystal display, in particular, a rear surface side protective film for a rear surface side polarizing plate, various adhesives and good adhesiveness, and a high total light transmittance after processing. Can be suitably used for applications that require.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Laminated Bodies (AREA)
  • Polarising Elements (AREA)

Abstract

Film polyester laminé permettant de résoudre les problèmes posés par l'emploi d'un film TAC, qui offre une bonne adhérence sur un agent adhésif, possède une transmissivité élevée pour tous les rayons lumineux et convient comme film protecteur pour un film de protection d'une membrane polarisante. Ce film polyester laminé est recouvert, sur une seule face, d'une couche formée par un liquide de revêtement contenant un alcool polyvinylique et un composé isocyanate ou un composé carbodiimide, et sur l'autre face d'une couche de revêtement dont la réflexivité absolue présente un minimum dans la plage de longueurs d'onde de 300-800 mm, ledit minimum de dépassant pas 3,5%.
PCT/JP2011/062918 2010-07-23 2011-06-06 Film polyester laminé WO2012011325A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2010165722A JP5608005B2 (ja) 2010-07-23 2010-07-23 積層ポリエステルフィルム
JP2010-165722 2010-07-23
JP2010-238517 2010-10-25
JP2010238517A JP5570389B2 (ja) 2010-10-25 2010-10-25 積層ポリエステルフィルム

Publications (1)

Publication Number Publication Date
WO2012011325A1 true WO2012011325A1 (fr) 2012-01-26

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PCT/JP2011/062918 WO2012011325A1 (fr) 2010-07-23 2011-06-06 Film polyester laminé

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Country Link
WO (1) WO2012011325A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006175628A (ja) * 2004-12-21 2006-07-06 Mitsubishi Polyester Film Copp 反射防止フィルム用ポリエステルフィルムおよび反射防止フィルム
JP2010089311A (ja) * 2008-10-06 2010-04-22 Mitsubishi Plastics Inc 積層ポリエステルフィルム
JP2010131937A (ja) * 2008-12-08 2010-06-17 Mitsubishi Plastics Inc 積層ポリエステルフィルム

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006175628A (ja) * 2004-12-21 2006-07-06 Mitsubishi Polyester Film Copp 反射防止フィルム用ポリエステルフィルムおよび反射防止フィルム
JP2010089311A (ja) * 2008-10-06 2010-04-22 Mitsubishi Plastics Inc 積層ポリエステルフィルム
JP2010131937A (ja) * 2008-12-08 2010-06-17 Mitsubishi Plastics Inc 積層ポリエステルフィルム

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