JP2007055064A - Laminated polyester film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film laminated with a hard coat layer which is excellent in adhesive properties and surface hardness and in which the occurrence of an interference pattern is suppressed. <P>SOLUTION: In the laminated polyester film which is made of at least two polyester resins different in ΔTcg (cold crystallization temperature-glass transition temperature), the hard coat layer is laminated on a polyester substrate film made of a polyester resin (A) with a ΔTcg of 55°C or below. The average wave reflection factor width of the wave curve of a reflection factor in a wavelength range of 400-600 nm measured from the side of the hard coat layer is 2% or below, and haze is 3% or below. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laminated polyester film, and more particularly to a laminated polyester film having a hard coat function with excellent scratch resistance and less interference fringes suitable for an antireflection film and a touch panel film.

  Biaxially oriented polyester film has excellent properties such as mechanical properties, dimensional stability, heat resistance, transparency, and electrical insulation properties. Therefore, magnetic recording materials, packaging materials, electrical insulation materials, various photographic applications, graphic arts, etc. It is used in many applications such as optical display materials. However, the surface hardness is not sufficient, and there is a drawback that the surface is easily damaged by contact with other hard materials, friction, scratching, and the like. In order to solve this, conventionally, a method of laminating various hard coat layers has been applied.

  In general, the hard coat layer often has insufficient adhesion to a biaxially oriented polyester film, and an adhesive layer is provided at the interface.

  When a hard coat layer is provided on such a method or directly on a biaxially oriented polyester film, an in-plane refractive index difference occurs between the hard coat layer and the biaxially oriented polyester surface or the adhesive layer surface that is in contact with the hard coat layer. In addition, when used as a base material for optical applications, for example, an antireflection film or a touch panel film, an interference pattern corresponding to the uneven thickness of the hard coat layer is generated.

  The occurrence of the interference pattern significantly impairs the visibility of the display when used in the above-described applications. In order to improve this phenomenon, studies have been made to improve the accuracy of the coating thickness or to increase the refractive index of the hard coat layer to reduce the difference in refractive index from the base film (Patent Document 1).

  Also, a method of embossing the surface of the base film by a hot press method to provide irregularities on the surface and providing a hard coat layer on the surface (Patent Document 2), a hard coat using a solvent that dissolves the base film A method of dissolving or swelling a base material at the time of application using a layer forming paint (Patent Document 3) has been proposed. However, there is a limit to match the refractive index of the hard coat layer and the adhesive layer to about 1.60 to 1.65, which is the in-plane refractive index of the biaxially oriented polyester. However, the interference pattern has not been completely erased.

In addition, the method of forming irregularities on the surface of the base film by a method such as hot pressing and providing a hard coat layer results in insufficient uniformity at the time of coating or contains bubbles in the hard coat layer by biting bubbles There are problems such as. Furthermore, the method of dissolving or swelling the base film is a biaxially oriented polyester film that has excellent solvent resistance, so there is almost no compatible solvent, and the only ortho-chlorophenol that can be used can adversely affect the working environment. There is a problem that it cannot be easily removed.
JP 2002-241527 A JP-A-8-197670 JP-A-2003-205563

  An object of the present invention is to provide a laminated polyester film that solves the above problems in a polyester film laminated with a hard coat layer, is excellent in adhesion to a base polyester film, surface hardness, and has reduced interference fringes.

As a result of intensive studies to achieve this goal,
(1) A hard coat layer on a polyester base film comprising at least two types of polyester resins having different ΔTcg (cold crystallization temperature-glass transition temperature), one of which is a polyester resin (A) having a ΔTcg of 55 ° C. or less. Is a laminated polyester film in which the average waviness reflectance width of the waviness curve of the reflectance measured from the hard coat layer side at a wavelength of 400 to 600 nm is 2% or less and the haze is 3% or less. Laminated polyester film,
(2) The laminated polyester film according to (1), wherein an adhesive layer is not interposed at the interface between the polyester film and the hard coat layer,
(3) The laminated polyester film according to (1) or (2), wherein the polyester film contains an ultraviolet absorber,
Is found.

  The laminated polyester film of the present invention has excellent visibility when applied to a display application, etc., because it is excellent in adhesiveness and surface hardness with the base polyester film, and has reduced interference fringes, by adopting the above-described configuration. It becomes.

  In the present invention, a laminated polyester film having a structure in which a hard coat layer is laminated on a base polyester film composed of at least two kinds of polyester resins having different ΔTcg, wherein at least one kind of ΔTcg is 55 ° C. or less. It is a polyester base film made of polyester (A) and polyester (B) having a ΔTcg greater than 55 ° C. ΔTcg defined in the present invention refers to a value represented by the following formula.

ΔTcg (° C.) = Tcc (° C.) − Tg (° C.)
(A glass transition temperature (Tg (° C.)) obtained by reading a sample obtained by melting a polyester resin at a temperature equal to or higher than the melting point and rapidly cooling to 0 ° C. or lower with a DSC at a temperature rising rate of 10 ° C./min. Cold crystallization temperature (difference in Tcc (° C))
ΔTcg is a parameter representing the crystallization rate. When this value is large, the crystallization rate is slow, and when it is small, the crystallization rate is fast. For example, in the case of polyethylene terephthalate, which is a typical example of polyester, when ΔTcg is 55 ° C. or lower, the crystallization speed is increased. In the present invention, at least two types of polyester resins having different ΔTcg are used as the constituent components of the base polyester film, and one of them needs to have a ΔTcg of 55 ° C. or lower. Protrusion for reducing interference fringes is insufficient when it is composed only of a resin with ΔTcg exceeding 55 ° C., and transparency is insufficient when it is composed only of a polyester resin with ΔTcg of 55 ° C. or less. become. Here, the protrusion described in the present invention is present at the interface between the hard coat layer and the polyester film and has an effect of reducing interference fringes. The protrusions present at the interface are effective for subdividing the area of the interface where light is reflected, and the interference fringes are reduced by subdividing the interference pattern into an invisible region.

  The polyester resin (A) having a ΔTcg of 55 ° C. or lower is not particularly limited, but at least one structural unit selected from ethylene terephthalate, ethylene isophthalate, ethylene naphthalate, and ethylene isonaphthalate units is used as a main constituent component. A polyester having ethylene terephthalate as a main repeating unit is preferable. In order to reduce ΔTcg, it is effective to have lithium acetate, magnesium acetate, potassium acetate, phosphorous acid, phosphonic acid, phosphinic acid or their derivatives, antimony oxide, and germanium oxide present during transesterification and polymerization. A particularly desirable combination is magnesium acetate and phosphonic acid (or a derivative thereof) and antimony oxide. As the phosphonic acid (or a derivative thereof), phenylphosphonic acid, dimethylphenyl phosphate and the like are suitable.

  In order to increase the mobility of the molecule and obtain a polyester having a high crystallization speed, it is effective to add a small amount of a flexible movable component or copolymerize it. Here, the flexible movable component refers to a component having a long flexible chain in the main chain and having a high affinity or copolymerization with the polyester, such as a long-chain aliphatic dicarboxylic acid, a long-chain aliphatic diol, An alkylene glycol or the like is used, and it is particularly effective to use a polyalkylene glycol such as polyethylene glycol, polypropylene glycol or hexamethylene glycol. Among these, a polyethylene glycol having a number average molecular weight of 200 to 50000 or less, preferably 1000 or more and 40000 or less, more preferably 2000 or more and 30000 or less, is 0.01% by weight or more and 15% by weight or less, preferably 0.1% by weight. % To 13% by weight, more preferably 1% to 10% by weight.

  The manufacturing method of a polyester resin (A) is not specifically limited, It can obtain by the normal polycondensation method of polyester.

  Although it is essential for the polyester base film to contain the polyester resin (A), the composition ratio is selected depending on the balance with the interference fringe reduction effect and transparency. In the present invention, the composition ratio of the polyester resin (A) is 0.1 to 30% by weight, preferably 0.3 to 15% by weight, based on 100% by weight of the entire polyester base film, and the polyester resin (A) It is essential to contain a polyester resin (B) having a ΔTcg greater than 55 ° C. as a constituent component other than the above.

 The type of the polyester resin (B) is not particularly limited as long as ΔTcg is greater than 55 ° C, but preferably 60 ° C to 85 ° C, more preferably about 65 ° C to 80 ° C. Specifically, it is a composition containing polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate and copolymers thereof, and can be obtained by a conventionally known polymerization method. Intrinsic viscosity (measured in o-chlorophenol at 25 ° C. in accordance with JIS K7367) as a measure of the degree of polymerization of the polyester resins (A) and (B) is 0.4 to 1.2 dl / g, preferably 0.8. 5 to 0.8 dl / g is desirable in terms of film forming properties, mechanical properties of the film, and the like.

  In the laminated polyester film of the present invention, a hard coat layer is laminated on at least one surface of the above-described polyester base film, but this hard coat layer is not particularly limited, and for example, acrylic, urethane, urethane acrylate System, melamine system, organic silicate compound system, silicone system and metal oxide. Among these, an acrylic type that is cured by heat or actinic radiation is preferable, and a cured composition composed of a compound containing polyfunctional acrylate as a main component is preferable. Here, the ratio of the main component to the entire hard coat layer is 60% or more, preferably 70% or more.

  The polyfunctional acrylate constituting the hard coat layer is a monomer, oligomer, or prepolymer having 3 (more preferably 4, more preferably 5) or more (meth) acryloyloxy groups in one molecule. 1 or more (meth) acryloyloxy groups in one molecule (in the present specification, “... (meth) acryl ...” means “... acryl ... or ... methacryl”) ... ”))), The polyhydric alcohol having 3 or more alcoholic hydroxyl groups in one molecule has 3 hydroxyl groups. The compound etc. which become the esterified substance of the above (meth) acrylic acid can be mentioned.

  Specific examples include pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, Dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, etc. Can be used. These may be used alone or in combination of two or more.

  The use ratio of the monomer, oligomer or prepolymer having 3 or more (meth) acryloyloxy groups in one molecule is preferably 50 to 90% by weight, more preferably based on the total amount of the constituent components of the hard coat layer. Is 50 to 80% by weight.

  In addition to the above-mentioned compounds, it is preferable to use one or two functional acrylates together for the purpose of relaxing the rigidity of the hard coat layer or reducing shrinkage during curing.

The monomer having 1 to 2 ethylenically unsaturated double bonds in one molecule can be used without particular limitation as long as it is a normal monomer having radical polymerizability.
As the compound having two ethylenically unsaturated double bonds in the molecule, the following (a) to (f) (meth) acrylates and the like can be used. That is,
(A) C2-C12 alkylene glycol (meth) acrylic acid diesters: ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl Glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, etc.
(B) (Meth) acrylate diesters of polyoxyalkylene glycol: diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, Polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, etc.
(C) Polyhydric alcohol (meth) acrylic acid diesters: pentaerythritol di (meth) acrylate, etc.
(D) (Meth) acrylic acid diesters of ethylene oxide and propylene oxide adducts of bisphenol A or bisphenol A hydride: 2,2′-bis (4-acryloxyethoxyphenyl) propane, 2,2′-bis ( 4-acryloxypropoxyphenyl) propane, etc.
(E) Two or more in a molecule obtained by reacting a terminal isocyanate group-containing compound obtained by reacting a diisocyanate compound and two or more alcoholic hydroxyl group-containing compounds in advance with an alcoholic hydroxyl group-containing (meth) acrylate. Urethane (meth) acrylates having a (meth) acryloyloxy group, and the like, and
(F) Epoxy (meth) acrylates having two or more (meth) acryloyloxy groups in a molecule obtained by reacting a compound having two or more epoxy groups in the molecule with acrylic acid or methacrylic acid. Examples of the compound having one ethylenically unsaturated double bond in the molecule include methyl (meth) acrylate, ethyl (meth) acrylate, n- and i-propyl (meth) acrylate, n-, sec- and t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, hydroxyethyl (meth) ) Acrylate, polyethylene glycol mono (meth) a Relate, polypropylene glycol mono (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, N-hydroxyethyl (meth) acrylamide, N-vinylpyrrolidone, N-vinyl-3-methylpyrrolidone, N-vinyl -5-methylpyrrolidone and the like can be used. These monomers may be used alone or in combination of two or more.

  The use ratio of the monomer having 1 to 2 ethylenically unsaturated double bonds in one molecule is preferably 10 to 40% by weight, more preferably 20 to 20% by weight based on the total amount of the constituent components of the hard coat layer. 40% by weight. Acrylic oligomers include polyester acrylates, urethane acrylates, epoxy acrylates and polyether acrylates, including those in which a reactive acrylic group is bonded to an acrylic resin skeleton, and rigid materials such as melamine and isocyanuric acid. A structure in which an acrylic group is bonded to a simple skeleton may be used.

  Moreover, a reactive diluent can be used suitably. A reactive diluent is a coating agent component having a group that reacts with a monofunctional or polyfunctional acrylic oligomer as well as serving as a solvent in the coating process as a coating medium. It will be.

  Specific examples of these acrylic oligomers, reactive diluents, and the like can be found in Shinzo Yamashita, Tosuke Kaneko, “Crosslinking Agent Handbook”, published in Taiseisha 1981, pages 267 to 275, pages 562 to 593. However, the present invention is not limited to these.

  Commercially available polyfunctional acrylic cured paints include Mitsubishi Rayon Co., Ltd. (trade name “Diabeam” series, etc.), Nagase Sangyo Co., Ltd. (trade name “Denacol” series, etc.), Shin-Nakamura Co., Ltd .; (Product name “NK Ester” series, etc.), Dainippon Ink and Chemicals Co., Ltd .; (Product name “UNIDIC” series, etc.), Toa Gosei Chemical Industries Co., Ltd. (product name “Aronix” series, etc.), Nippon Oils and Fats Co., Ltd. (Trade name “Blemmer” series, etc.), Nippon Kayaku Co., Ltd .; (trade name “KAYARAD” series, etc.), Kyoeisha Chemical Co., Ltd .; (trade names “light ester” series, “light acrylate” series, etc.) The product can be used.

  In the present invention, as a modifier for the hard coat layer, a coating property improver, an antifoaming agent, a thickener, an antistatic agent, inorganic particles, organic particles, an organic lubricant, an organic polymer compound, an ultraviolet ray, Absorbers, light stabilizers, dyes, pigments or stabilizers can be used, and these are used as a composition component of the coating layer constituting the hard coat layer within a range that does not impair the reaction due to active rays or heat, The properties of the hard coat layer can be improved depending on the application.

  In the present invention, as a method of curing the above hard coat composition, for example, a method of irradiating ultraviolet rays as active rays, a high temperature heating method, or the like can be used. It is desirable to add a photopolymerization initiator or a thermal polymerization initiator to the composition.

  Specific examples of the photopolymerization initiator include acetophenone, 2,2-diethoxyacetophenone, p-dimethylacetophenone, p-dimethylaminopropiophenone, benzophenone, 2-chlorobenzophenone, 4,4′-dichlorobenzophenone, 4,4′-bisdiethylaminobenzophenone, Michler's ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, methylbenzoyl formate, p-isopropyl-α-hydroxyisobutylphenone, α-hydroxyisobutylphenone, 2, Carbonyl compounds such as 2-dimethoxy-2-phenylacetophenone and 1-hydroxycyclohexyl phenyl ketone, tetramethylthiuram monosulfide, tetramethylthio Sulfur compounds such as uranium disulfide, thioxanthone, 2-chlorothioxanthone, and 2-methylthioxanthone can be used. These photopolymerization initiators may be used alone or in combination of two or more. Moreover, as a thermal polymerization initiator, a peroxide compound such as benzoyl peroxide or di-t-butyl peroxide can be used.

  The amount of the photopolymerization initiator or thermal polymerization initiator used is suitably 0.01 to 10 parts by weight with respect to 100 parts by weight of the hard coat layer forming composition. When an electron beam or gamma ray is used as a curing means, it is not always necessary to add a polymerization initiator. Further, when thermosetting at a high temperature of 200 ° C. or higher, it is not always necessary to add a thermal polymerization initiator.

  The hard coat layer forming composition used in the present invention has a thermal polymerization prevention such as hydroquinone, hydroquinone monomethyl ether or 2,5-t-butyl hydroquinone in order to prevent thermal polymerization during production and dark reaction during storage. It is desirable to add an agent. The addition amount of the thermal polymerization inhibitor is preferably 0.005 to 0.05% by weight with respect to the total weight of the hard coat layer forming composition.

  In the present invention, it is preferable to contain an isocyanate compound or a melamine-based crosslinking agent in the coating agent for forming the hard coat layer for the purpose of improving the adhesion with the base polyester film and reducing interference fringes observed from the hard coat layer surface. . As the isocyanate compound, known compounds can be used. For example, 2,4- and / or 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate (abbreviated as MDI), polymeric MDI, 1,5 -Naphthylene diisocyanate, tolidine diisocyanate, 1,6-hexamethylene diisocyanate (abbreviated as HDI), trimethylhexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate (abbreviated as XDI), hydrogenated XDI, hydrogenated MDI, lysine diisocyanate, tri Examples thereof include monomers such as phenylmethane triisocyanate and tris (isocyanatephenyl) thiophosphate, and dimers or more. These may be used alone or in combination of two or more. The type of melamine crosslinking agent is not particularly limited, but melamine, a methylolated melamine derivative obtained by condensing melamine and formaldehyde, a compound partially or completely etherified by reacting a methylolated melamine with a lower alcohol, or These mixtures can be used. As the melamine-based crosslinking agent, a monomer, a condensate composed of a multimer of two or more, or a mixture thereof can be used.

  As the lower alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butanol, isobutanol and the like can be used. The functional group has an imino group, a methylol group, or an alkoxymethyl group such as a methoxymethyl group or a butoxymethyl group in one molecule, and an imino group type methylated melamine, a methylol group type melamine, or a methylol group type methylated melamine. And fully alkyl methylated melamine. Of these, methylolated melamine and fully alkylated melamine are preferred in terms of adhesion and interference fringes-free. The amount of the isocyanate compound and the melamine-based crosslinking agent is not particularly limited, but it is 2 to 40% by weight, preferably 5 to 30% by weight in the solid content of the hard coat forming coating, and the balance of adhesion, hardness and interference fringe reduction. This is preferable.

In addition, it is preferable to use an acid catalyst in combination for the purpose of accelerating the curing of melamine. As the acid catalyst, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dimethyl pyrophosphoric acid, styrene sulfonic acid, and derivatives thereof (for example, blocking agent adducts such as dimethylethanolamine) can be preferably used. The amount of the acid catalyst added is 0.05 to 10% by weight, preferably 1 to 5% by weight, based on the melamine crosslinking agent. When a melamine-based crosslinking agent is added, it is particularly preferable to use a polyfunctional acrylate having at least one hydroxyl group as a preferred form of the coating composition in terms of improving adhesiveness.

  In forming the hard coat layer of the present invention, it is preferable to use a leveling agent to smooth the surface of the hard coat layer. Typical leveling agents include silicone-based, acrylic-based, and fluorine-based agents, but when only smoothness is required, silicone-based is effective with a small amount of addition. As the silicone leveling agent, polydimethylsiloxane as a basic skeleton and a polyoxyalkylene group added thereto (for example, SH190 manufactured by Toray Dow Corning Silicone Co., Ltd.) are suitable.

  On the other hand, in the case where a laminated film is further provided on the hard coat layer, it is necessary that the coating properties and adhesiveness of the laminated film are not impaired. In that case, it is preferable to use an acrylic leveling agent. As such a leveling agent, “ARUFON-UP1000 series, UH2000 series, UC3000 series (trade name): manufactured by Toagosei Co., Ltd.” or the like is preferably used. The leveling agent is preferably added in an amount of 0.01 to 5% by weight in the hard coat layer forming composition.

  In the present invention, a polyester-based, acrylic-based, polyurethane-based or other adhesive layer may be interposed between the polyester film and the hard coat layer as necessary, but this reduces adhesiveness and interference fringes under wet heat. Therefore, it is preferable not to interpose an adhesive layer. When the adhesive layer is interposed, interference fringes may be generated due to a difference in refractive index from the polyester film or the hard coat layer, or the adhesive layer may be deteriorated by ultraviolet rays or may have poor durability in high temperature and high humidity conditions.

In the laminated polyester film of the present invention, the average waviness amplitude of reflectance at a wavelength of 400 to 600 nm measured from the hard coat layer side is required to be 2% or less, preferably 1.5% or less, more preferably Is preferably 0.8% or less because interference fringes can be reduced.
The average waviness amplitude of the reflectance at a wavelength of 400 to 600 nm represents the intensity of light reflected at the interface between the polyester film and the hard coat layer. When this value is small, the interference fringe pattern becomes difficult to see, and when it is large, Since the interference fringe pattern can be clearly seen in the present invention, the interference fringe is reduced by setting the value to 2% or less in the present invention. It can be done.

  The average waviness amplitude of the reflectance at a wavelength of 400 to 600 nm described in the present invention is measured by the following method. First, the hard coat surface of the hard coat film is used as a measurement surface, and the opposite surface is roughened with sandpaper or the like so that the 60 ° C. gloss (JIS Z 8741) is 10 or less. Next, the roughened portion is colored black so that the visible light average transmittance at a wavelength of 400 to 600 nm is 5% or less to obtain a measurement sample. FIG. 1 shows the results observed when the measurement surface is measured with a spectrophotometer at an incident angle of 10 degrees. In FIG. 1, curve (c) shows the relationship between the wavelength and the measured reflectance. In the reflectance, the undulation at a wavelength of 400 to 600 nm, that is, the maximal value in the calculus meaning of the fluctuation of the reflectance up and down with the change of the wavelength (first derivative = 0, second derivative <0) The difference between the local minimum values (primary differential coefficient = 0, secondary differential coefficient> 0) is defined as waviness amplitude (a). As shown in FIG. 1, a line (peak line (b)) connecting the peaks (maximum points) of the undulations of reflectance at wavelengths of 400 to 600 nm and a line (valley line) connecting the valley bottoms (minimum points) of the undulations. The difference between the two reflectance line graphs in (d)), that is, the undulation amplitude (a) including 11 sampling points (wavelength is (400 + 20 * i (i = i = 12)) including the boundary point (400, 600 nm). An integer of 0 to 10))) is obtained at a place where nm is obtained, and a value obtained by averaging these 11 values is defined as an average undulation amplitude.

In the present invention, in order to make the average waviness reflectance width of the waviness curve of the reflectance measured from the hard coat layer side at a wavelength of 400 to 600 nm 2% or less, fine protrusions are formed at the interface between the base polyester film and the hard coat layer. Preferably it is formed. The shape and size of the protrusion is not particularly limited, but the preferable protrusion size length is 0.1 to 100 μm, preferably 0.1 to 30 μm, the width is 0.05 μm to 20 μm, preferably 0.05 μm to 10 μm, When the height is 0.05 μm to 2 μm, preferably 0.1 μm to 1 μm, the effect of reducing interference fringes is large without reducing transparency. The shape and size of the protrusions are not particularly limited, but can be measured by the method described below. Using a differential interference microscope (Leica inspection / research microscope DMLM: Leica Microsystems), observe the measurement surface at 50x magnification in transmitted light mode, identify the protrusion from the photographed image, and observe its shape. Measure the size in the width and longitudinal directions. The measurement was the average value of the total number of protrusions observed within the viewing angle. In addition, the height of the protrusion was observed using a 50 × lens with a laser microscope (ultra-deep shape measurement microscope VK-8500: manufactured by Keyence Corporation), and image processing (specifically, each protrusion had a valley bottom). Connect the parts with a line, draw a perpendicular from the top of the protrusion and measure the distance to the intersection), and set the average value of all protrusions adjacent to one protrusion as the height of the protrusion.
Such interfacial protrusions can be obtained by the following film forming method.

  A polyester composition containing a polyester resin (A) that has been sufficiently dried and from which moisture has been removed is melt-extruded, and cooling speed is applied to the drum surface and non-drum surface in the process of cooling with a cooled metal mirror drum using an electrostatic application casting method. Although there is a difference, crystallization of the polyester resin (A) having a small crystallization speed and a small ΔTcg proceeds on the non-drum surface side where the cooling rate is slow.

  When the film is thin or formed at a high speed, the crystallization may not progress sufficiently even on the non-drum surface. In such a case, a method of heating the film on the non-drum surface side, for example, hot air It is preferable to use a method such as spraying or heating with a heater. On the contrary, when the film is very thick or when the film forming speed is extremely slow, it is preferable to use a method of actively cooling the film on the non-drum surface side, for example, a method of blowing cold air.

  Next, this unstretched film is biaxially stretched and heat-set by a known method to obtain a biaxially oriented polyester film. At the time of stretching, crystals depending on the polyester resin (A) serve as nuclei and protrusions are formed on the surface. Here, when the polyester resin (A) is used, if the thickness of the unstretched film is 100 μm to 3000 μm, the temperature is 5 to 50 ° C. higher than the melting point of the polyester resin (A) without special heating or cooling treatment at the time of casting. By cooling the film extruded in step 5 on a cooling drum at 5 to 50 ° C., crystallization proceeds in the surface layer portion of the non-drum surface, and sufficient protrusions can be formed after biaxial stretching. As the stretching method, a normal sequential biaxial stretching method and a simultaneous biaxial stretching method can be applied, but the sequential biaxial stretching method is preferable from the viewpoint of forming a protrusion.

  In the sequential biaxial stretching method, stretching in the longitudinal direction is preferably performed at a temperature 15 ° C. or more higher than the glass transition point of the polyester resin (A) and stretched 3 to 6 times at a stretching speed of 5000 to 50000% / min. The stretching in the width direction is preferably performed at a temperature of 80 ° C. to 160 ° C. at a rate of 1000 to 20000% / min, 2 to 7 times. Further, the film stretched in the longitudinal direction and the width direction may be further stretched in the longitudinal direction and the width direction. The heat treatment after stretching is desirably performed at 170 to 250 ° C. for 0.5 to 60 seconds.

  The thickness of the base polyester film of the present invention is not particularly limited, and may be appropriately set according to the use, but is usually about 10 to 500 μm, and about 75 to 250 μm when applied to display uses. desirable.

  In addition, the laminated polyester film of the present invention preferably has a transmittance of 5% or less at a wavelength of 380 nm, and this can protect the substrate and dye pigments from ultraviolet rays, particularly when applied to plasma display members. it can.

  In the laminated polyester film of the present invention, the haze is 3% or less, preferably 2% or less, more preferably 1% or less. When the haze exceeds 3%, the transparency is lowered, and when it is used for a display member, it is not preferable because the visibility and sharpness of an image are inferior.

  Further, the laminated polyester film of the present invention preferably has a transmission b value of 1.5 or less. If the transmission b value exceeds 1.5, the film itself appears slightly yellowish, which may impair the sharpness of the image.

  The polyester film of the laminated polyester film of the present invention may contain various additives, resin compositions, cross-linking agents and the like within a range that does not impair the effects of the present invention. For example, antioxidants, heat stabilizers, ultraviolet absorbers, organic and inorganic particles (for example, silica, colloidal silica, alumina, alumina sol, kaolin, talc, mica, calcium carbonate, barium sulfate, carbon black, zeolite, titanium oxide, Metal fine powders), pigments, dyes, antistatic agents, nucleating agents, acrylic resins, polyester resins, urethane resins, polyolefin resins, polycarbonate resins, alkyd resins, epoxy resins, urea resins, phenol resins, silicone resins, rubber resins , Wax composition, melamine crosslinking agent, oxazoline crosslinking agent, methylolated, alkylolized urea crosslinking agent, acrylamide, polyamide, epoxy resin, isocyanate compound, aziridine compound, various silane coupling agents, various titanates And the like can be mentioned system coupling agent.

  Particularly when used for a plasma display, the polyester film preferably has an ultraviolet cut function and preferably contains an ultraviolet absorber in order to use a dye having a color correction function and a near infrared cut function.

Preferred examples of the ultraviolet absorber include salicylic acid compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, benzoxazinone compounds, and cyclic imino ester compounds, but 380 nm to 390 nm. Of these, benzoxazinone compounds are most preferred from the viewpoints of UV-cutting property and color tone. These compounds may be used alone or in combination of two or more. Moreover, combined use of stabilizers, such as HALS (hindered amine light stabilizer) and antioxidant, is more preferable.
Examples of benzoxazinone-based compounds that are preferable materials include 2-p-nitrophenyl-3,1-benzoxazin-4-one and 2- (p-bezoylphenyl) -3,1-benzoxazine-4. -One, 2- (2-naphthyl) -3,1-benzoxazin-4-one, 2-2'-p-phenylenebis (3,1-benzoxazin-4-one), 2,2 '-( 2,6-naphthylene) bis (3,1-benzoxazin-4-one) and the like can be exemplified. The addition amount of these compounds is preferably 0.05 to 1.0% by weight in the polyester film.

  Moreover, it is preferable to use a cyanoacrylate-based tetramer compound in combination in order to impart further excellent light resistance. The cyanoacrylate tetramer compound is preferably contained in the polyester film in an amount of 0.05 to 2% by weight. The cyanoacrylate-based tetramer compound is a compound based on a tetramer of cyanoacrylate, such as 1,3-bis (2′cyano-3,3-diphenylacryloyloxy) -2, 2-bis-. (2 'cyano-3,3-diphenylacryloyloxymethylpropane). When used in combination with this, the aforementioned ultraviolet absorber is preferably 0.3 to 3% by weight in the base film.

  In addition, the laminated polyester film of the present invention can be obtained by laminating a hard coat layer with an adhesive layer interposed as necessary on the projection forming surface side of the polyester film, but a more preferable method is to interpose an adhesive. In order to directly bond the hard coat layer and reduce interference fringes, it is effective to use the following method.

  The laminated polyester film of the present invention can be produced by the following method.

  In the production method of the laminated polyester film of the present invention, the above-mentioned film forming method for forming the protrusion is used. Here, the protrusion forming surface side in the stage of the polyester film which is uniaxially stretched and crystal orientation is incomplete. A hard coat composition coating is applied to the coating. Thereafter, the film is stretched in a direction perpendicular to the uniaxial stretching direction through a preheating step, heat fixed, and further subjected to active ray irradiation treatment as necessary.

  By applying this method, protrusions can be formed on the polyester base film, and the hard coat layer can be highly adhered on the polyester base film without providing a primer layer. The laminated polyester film of the present invention thus obtained can be provided with a hard coat layer all at once in the film forming process, so that the productivity is good, the surface hardness is high, the wear resistance is excellent, the hard coat layer and Since the adhesiveness with the base film is excellent and the interference fringes are suppressed and the visibility is excellent, it can be used in a wide range of applications. In particular, it is suitably used as an antireflection film substrate for displays, a substrate for touch panels, a substrate for windowing, a substrate for nameplates, and the like.

  Various coating methods such as a reverse coating method, a gravure coating method, a rod coating method, a bar coating method, a die coating method, or a spray coating method can be used as a means for applying the hard coat layer forming coating agent.

  Examples of the active rays used as necessary in the present invention include electromagnetic waves that polymerize acrylic vinyl groups such as ultraviolet rays, electron beams and radiation (α rays, β rays, γ rays, etc.). Ultraviolet light is convenient and preferred. As the ultraviolet ray source, an ultraviolet fluorescent lamp, a low pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a xenon lamp, a carbon arc lamp, or the like can be used. Moreover, when irradiating actinic radiation, if it irradiates under a low oxygen concentration, it can harden | cure efficiently. Furthermore, the electron beam system is advantageous in that the apparatus is expensive and needs to be operated under an inert gas, but it is not necessary to include a photopolymerization initiator or a photosensitizer in the coating layer. is there.

  As the heat necessary for the thermosetting used in the present invention, steam heater, electric heater, infrared heater or far-infrared heater is used. The heat given by spraying on the base material and the coating film using is used. Among them, heat by air heated to 200 ° C. or higher is preferable, more preferably heat by nitrogen heated to 200 ° C. or higher. It is preferable because the curing rate is high. Although what is necessary is just to determine the thickness of a hard-coat layer according to a use, 0.5 micrometers-30 micrometers are preferable normally, More preferably, they are 1 micrometer-15 micrometers. When the thickness of the hard coat layer is less than 0.5 μm, even if it is sufficiently cured, the surface hardness is not sufficient because it is too thin, and the surface tends to be scratched. On the other hand, when the thickness exceeds 30 μm Tends to curl at the time of curing or cracks in the cured film due to stress such as bending.

  Moreover, you may provide printing layers, such as a pattern, in the outermost layer of a hard-coat layer in the range which does not impair the effect of this invention.

  In addition, the laminated polyester film of the present invention can be used by being bonded to various functional films by various methods, and an adhesive layer can be laminated on the other surface or a conductive layer can be provided.

  For example, the opposite surface of the laminated polyester film of the present invention on which the hard coat layer is provided is bonded to a counterpart material using various adhesives, and the hard coat layer such as wear resistance and scratch resistance is attached to the counterpart material. It can also be used with a function. The pressure-sensitive adhesive used at this time is not particularly limited as long as it is a pressure-sensitive adhesive (adhesive) that adheres two objects by its pressure-sensitive action, and is a pressure-sensitive adhesive made of rubber, acrylic, silicone or polyvinyl ether. (Adhesive) can be used.

  Furthermore, the pressure-sensitive adhesive is roughly classified into two types, a solvent-type pressure-sensitive adhesive and a solventless pressure-sensitive adhesive. Solvent-type pressure-sensitive adhesives excellent in dryness, productivity, and processability are still mainstream, but in recent years, they are changing to solvent-free pressure-sensitive adhesives in terms of pollution, energy saving, resource saving, safety, and the like. Among these, it is preferable to use an actinic radiation curable pressure sensitive adhesive that is a pressure sensitive adhesive that is cured in seconds by irradiation with actinic radiation and has excellent properties such as flexibility, adhesion, and chemical resistance.

  Specific examples of the actinic radiation curable acrylic pressure-sensitive adhesive can be referred to the Japan Adhesive Society, “Adhesive Data Book”, published by Nikkan Kogyo Shimbun, 1990, pages 83 to 88. It is not limited to. Commercially available multifunctional acrylic UV curable paints, such as Hitachi Chemical Polymer Co., Ltd. (trade name “XY” series, etc.), Toho Kasei Kogyo Co., Ltd. (trade name “Hi-Rock” series, etc.), Three Bond Co., Ltd. ( Product names such as “Three Bond” series), Toa Gosei Chemical Industry Co., Ltd .; (Product name “Arontite” series, etc.), Cemedine Co., Ltd .; (Product name “Cemeloc Super” series, etc.) can be used. However, it is not limited to these.

  When this type of pressure-sensitive adhesive is applied to a normal biaxially stretched polyester film, the adhesiveness becomes insufficient, and various primer treatments, for example, a laminated film made of an acrylic resin, a polyester resin, a urethane resin, etc. are provided. Thereby, the adhesiveness of a polyester film and an adhesive layer can be improved.

  In the present invention, a hard coat layer can be formed on one side, and a primer layer for improving the adhesiveness with these pressure-sensitive adhesive layers can be formed on the opposite side. It goes without saying that when the coating solution containing the actinic radiation curable or thermosetting composition to be formed is applied, it may be applied to the back side of the coating solution at the same time, dried and optionally stretched.

  In addition, when the laminated polyester film of the present invention is used as an antireflection film such as a plasma display, it is preferably used by providing a high refractive index layer on the hard coat layer and further providing a low refractive index layer thereon. be able to.

  Although it does not specifically limit as a high refractive index layer, It is a thing with a refractive index of about 1.55-1.70, and it is preferable that a laminated thickness shall be 0.03-0.15 micrometer. Such a high refractive index layer can be obtained by finely dispersing metal compound particles in a binder component. The binder component is not particularly limited, and general-purpose resins such as polyester, acrylic, urethane, epoxy, and the hard coat component described in the present invention can be used. The metal compound particle itself has a high refractive index, and specifically includes tin-containing antimony oxide particles, zinc-containing antimony oxide particles, tin-containing indium oxide particles, zinc oxide / aluminum oxide particles, antimony oxide particles, and oxidation. Although titanium particles, zirconium oxide particles, and the like can be used, compounds capable of adding an antistatic function are more preferable, and tin-containing indium oxide particles are particularly preferable. The metal compound particles having an average primary particle diameter (sphere equivalent diameter according to the BET method) of 0.5 μm or less, preferably 0.001 to 0.3 μm, are preferable in terms of maintaining transparency. Organic conductive materials such as polypyrrole, polyaniline, and polythiophene can be added to these metal compounds for the purpose of further improving the conductivity.

  The low refractive index layer preferably has a refractive index of about 1.30 to 1.40, and the laminated thickness is preferably about 0.01 to 0.15 μm. As a material for forming the low refractive index layer, a known material can be applied, and a fluorine compound, a compound having a perfluoroalkyl group, and the like are preferable. It can also be achieved by filling hollow fine particles in the binder resin. Such hollow particles are disclosed, for example, in JP-A-2001-233611, J. Pat. AM. Chem. soc. 2003, 125, 316-317 and the like.

  The application method is not limited to application, but examples include microgravure coating, gravure coating, microgravure reverse coating, gravure reverse coating, die coating, comma coating, kiss coating, capillary coating, and wire bar coating. Among these, the micro gravure coat and the micro gravure reverse coat are preferable because the coating thickness accuracy is increased.

[Characteristic measurement method and effect evaluation method]
The characteristic measurement method and effect evaluation method in the present invention are as follows.

(1) ΔTcg
It was measured using DSC (Differential Scanning Calorimeter) type II manufactured by PerkinElmer. DSC measurement conditions are as follows. A measurement sample of 10 mg of polyester resin is collected and set in a DSC apparatus. After melting for 5 minutes at a temperature of 300 ° C., quench with liquid nitrogen for 5 minutes.
The sample is heated at 10 ° C./min, and the glass transition point (Tg) is detected. Further, the temperature rise is continued, and the crystallization exothermic peak temperature from the glass state (cold crystallization temperature Tcc (° C.)) is detected.
From the above measured values, ΔTcg was determined by the following equation. In addition, as a glass transition temperature (Tg), the midpoint glass transition temperature (Tmg) of JIS K7121-1987 is employ | adopted.

 ΔTcg (° C.) = Tcc (° C.) − Tg (° C.).

(2) Adhesion under normal conditions Under normal conditions (23 ° C., relative humidity 65%), 100 pieces of 1 mm ² crosscuts were put on the hard coat layer of the laminated polyester film, and cellophane tape made by Nichiban Co., Ltd. was applied thereon. And then reciprocating three times with a load of 19.6 N using a rubber roller, and after pressing, peeled off in the direction of 90 degrees, and evaluated in four steps according to the number of remaining hard coat layers (◎: 100, ○: 80-99, Δ: 50-79, x: 0-49). (◎) and (○) were considered to have good adhesion.

(3) Adhesive property under wet heat The laminated polyester film was allowed to stand for 48 hours under wet heat (80 ° C., relative humidity 85%). After the treatment, it was immediately taken out and allowed to stand for 5 minutes under normal conditions (23 ° C., relative humidity 65%), and then the same evaluation as (2) normal adhesion was performed.

(4) Abrasion resistance The surface of the hard coat layer was rubbed 10 times (speed: 10 cm / s) under a constant load with steel wool # 0000. This was performed by changing the load, and the maximum load having scratch resistance (not damaged) was examined. 2 kg / cm ² was a practically acceptable level and was accepted.

(5) Pencil hardness Measured according to JIS K-5400 using HEIDON (manufactured by Shinto Kagaku Co., Ltd.). 2H or higher was accepted.

(6) Measurement of surface reflectance and average waviness reflectance width The reflectance at an incident angle of 10 degrees was measured using a U-3410 type spectrophotometer equipped with a 60 mmφ integrating sphere manufactured by Hitachi.

  In order to eliminate the influence of reflection on the back surface of the measurement sample, after roughening the back surface of the measurement surface (hard coat layer surface side) with No. 240 sandpaper, the average visible light transmittance at a wavelength of 400 to 600 nm is 5% or less. It was colored with black magic ink. The determination of the presence or absence of the influence of the back surface reflection was judged to have no influence of the back surface reflection if the glossiness of the back surface after the treatment (incident angle 60 °, light receiving angle 60 °) was 10 or less. The glossiness was measured in accordance with JIS Z 8741 using a digital variable glossiness meter UGV-5B (manufactured by Suga Test Instruments Co., Ltd.).

  The reflectance at a wavelength of 400 to 600 nm is measured, and each wavelength (11 locations, 11 points, at a sample point of 20 nm interval) is connected to a line connecting the peak of the undulation (peak line) and a line connecting the valley bottom of the undulation (valley line). A difference (mountain line-valley line) at a wavelength of (400 + 20 * i (i = integer of 0 to 10)) nm) was determined, and the average was defined as the average swell reflectance width.

  Further, the average value of the peak line and the valley line at a wavelength of 550 nm was defined as the surface reflectance.

(7) Haze Using a direct reading haze computer manufactured by Suga Test Instruments Co., Ltd., the haze was measured based on JIS K-7105.

(8) Presence / absence of interference fringes After the surface of the measurement surface (hard coat layer surface side) is roughened with 240 sandpaper in the same manner as the measurement of surface reflectance and average waviness amplitude in order to eliminate the influence of back surface reflection. The sample prepared by coloring with black magic ink is placed in a dark room 30 cm directly under a three-wavelength fluorescent lamp (National Parrook, three-wavelength daylight white (FL 15EX-N 15W)). Evaluation was made based on whether or not the iris pattern was visible when visually observed.

Iris pattern is not visible: A rank Very weak iris pattern is visible: B rank Weak rainbow pattern is visible: C rank Strong rainbow color pattern is clearly visible: D rank.

(9) Visibility A photograph was placed in contact with the laminated polyester film, and it was examined whether or not the image was clearly visible when the photograph was viewed through the film.

The image looks clear: ◎
The image is slightly blurred: ○
The image is blurred and difficult to see:
I can't see the image: x.

(10) Total light transmittance Using a fully automatic direct reading haze computer HGM-2DP (manufactured by Suga Test Instruments Co., Ltd.), the total light transmittance in the thickness direction of the hard coat film was determined and used as the average value of 10-point measurement.

(11) Transmittance at 380 nm Transmittance at 380 nm with a Φ60 integrating sphere 130-063 (manufactured by Hitachi, Ltd.) and a 10 degree inclined spacer attached to a spectroscopic hardness meter U-3410 (manufactured by Hitachi, Ltd.) The average value of 10-point measurement was obtained.

(12) Light resistance test Using an ultraviolet degradation acceleration tester iSuper UV Tester SUV-W131 (manufactured by Iwasaki Electric Co., Ltd.), a forced ultraviolet irradiation test was performed under the following conditions, and the degree of deterioration after irradiation (yellowing degree) ) Was evaluated by the transmission b value.

"UV irradiation conditions"
Illuminance: 100 mW / cm ² , temperature: 60 ° C., relative humidity: 50% RH, irradiation time: 16 hours.

(13) Transmission b value Using a spectroscopic color difference meter SE-2000 type (manufactured by Nippon Denshoku Industries Co., Ltd.), the transmission b value was measured by the transmission method according to JIS-K-7105.

  EXAMPLES Next, although this invention is demonstrated based on an Example, this invention is not necessarily limited to these.

  A polyester resin was prepared by a conventional method using the following catalyst and additive components. The polyester resin is a copolyester having polyethylene terephthalate or ethylene terephthalate as the main repeating unit. The weight ratio of each component is a value based on 100% by weight of the polyester resin.

<Polyester resin A-1>
Transesterification catalyst: Magnesium acetate 0.1% by weight
Polymerization catalyst: 0.03% by weight of antimony trioxide
Thermal stabilizer during polymerization: 0.35% by weight of dimethylphenylphosphonate
Components added during polymerization: 2% by weight of polyethylene glycol having a number average molecular weight of 4000
Intrinsic viscosity: 0.64
Tg: 73 ° C.
Tcc: 126 ° C
ΔTcg: 53 ° C.

<Polyester resin A-2>
A polyester resin A-2 was produced in the same manner except that the polyethylene glycol in the polyester resin A-1 was changed as follows.

5% by weight of polyethylene glycol with a number average molecular weight of 20,000
Intrinsic viscosity: 0.64
Tg: 71 ° C.
Tcc: 118 ° C
ΔTcg: 47 ° C.

<Polyester resin B-1>
Transesterification catalyst: Magnesium acetate 0.1% by weight
Polymerization catalyst: 0.03% by weight of antimony trioxide
Thermal stabilizer during polymerization: 0.35% by weight of dimethylphenyl phosphate
Intrinsic viscosity: 0.62
Tg: 68 ° C
Tcc: 143 ° C
ΔTcg: 75 ° C.

<Polyester resin B-2>
Using a polyester resin B-1 which was vacuum-dried at 180 ° C. for 4 hours, a compound chip was prepared by using a biaxial vent extruder so that the addition amount of the following UV absorber was 7% by weight, and a master chip was produced. .

Ultraviolet absorber: 2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazin-4-one)
The following were used as the hard coat layer forming coating.

<Polyester resin B-3>
Transesterification catalyst: Magnesium acetate 0.06% by weight
Polymerization catalyst: 0.008% by weight of antimony trioxide
Thermal stabilizer during polymerization: Trimethyl phosphate 0.02% by weight
Component added during polymerization: 10% by weight of polyethylene glycol having a number average molecular weight of 20,000
Intrinsic viscosity: 0.63
Tg: 74 ° C.
Tcc: 138 ° C
ΔTcg: 64 ° C.

<Polyester resin B-4>
A polyester resin B-4 was prepared in the same manner except that the polyethylene glycol of the polyester resin B-3 was not added.

Intrinsic viscosity: 0.60
Tg: 70 ° C.
Tcc: 150 ° C
ΔTcg: 80 ° C.

<H-1>
A mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (KAYARAD-DPHA: Nippon Kayaku Co., Ltd.) 75% by weight
Trimethylolpropane / ethylene oxide modified triacrylate (M-350: manufactured by Toagosei Co., Ltd.) 25% by weight
-2 parts by weight of a photopolymerization initiator (Irgacure 184: manufactured by Ciba Specialty Chemicals) To do).

<H-2>
-Mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (KAYARAD-DPHA: Nippon Kayaku Co., Ltd.) 70 wt%
Trimethylolpropane / ethylene oxide modified triacrylate (M-350: manufactured by Toagosei Co., Ltd.) 10% by weight
・ Fully alkylated melamine (Cymel 303: Nippon Cytec Co., Ltd.) 20 wt% ・ Catalyst: Catalyst 602 (Nihon Cytec Co., Ltd.) 1 part by weight ・ Leveling agent: Alfon UP1000 (Toa Gosei Chemical Co., Ltd.) 0.2 parts by weight (the total of the mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate, trimethylolpropane / ethylene oxide-modified triacrylate, and fully alkylated melamine is 100 parts by weight).

(Examples 1-7, Comparative Examples 1-5)
Two types of polyester chips (polyester resin (A) and polyester resin (B)) mixed at the ratios shown in Tables 1 and 2 were sufficiently vacuum dried at 180 ° C. for 3 hours, and then supplied to an extruder at 285 ° C. After melting, the sheet was extruded from a T-shaped die into a sheet shape, wound around a mirror cast drum having a surface temperature of 20 ° C. using an electrostatic application casting method, cooled and solidified to obtain an unstretched sheet. At this time, the cooling time in the drum (drum contact time) was set to 2.5 seconds. The unstretched sheet thus obtained was preheated with a roll group heated to 75 ° C., and then stretched 3.5 times in the longitudinal direction at 95 ° C. A non-drum surface of this uniaxially stretched film was coated with a 3 wt% water dilution of an aqueous polyurethane resin (Hydran AP-10: manufactured by Dainippon Ink & Chemicals, Inc.) using a # 6 wire bar. Both ends of the coated film were gripped and led to a preheating zone at 85 ° C., and stretched 3.5 times in the width direction in a heating zone at 110 ° C. Thereafter, a heat treatment was performed for 15 seconds while continuously performing a relaxation treatment of 5% in a heat treatment zone at 225 ° C. The H-1 hard coat-forming coating agent was applied to the polyurethane resin-coated surface of the obtained 100 μm polyester film and cured by irradiation with ultraviolet rays at 350 mJ / cm ² intensity. The hard coat layer thickness was 6 μm. The evaluation results of the obtained film are shown in Table 1. In Examples 1-7, it was excellent in the adhesiveness with a base film, surface hardness, and the visibility with almost no interference fringes.
On the other hand, in Comparative Examples 1 to 3 and 5 in which ΔTcg exceeds the range of the present invention, the generation of interference fringes was remarkably insufficient. Further, when a single polyester resin having a ΔTcg of 55 ° C. or lower was used (Comparative Example 4), the surface was remarkably matted and the haze was high.

(Example 8)
Using the polyester resin mixed composition of Example 2, melt extrusion was performed in the same manner, and longitudinal stretching was further performed. The hard coat forming coating agent (H-2) was applied to the non-drum surface of the film after longitudinal stretching to a thickness of 20 μm. The film was continuously guided into the tenter while gripping both ends of the film, preheated at 85 ° C., and stretched 3.3 times in the width direction at 105 ° C. Thereafter, heat treatment was performed for 25 seconds while relaxing 5% in a heat treatment zone at 235 ° C. continuously.
The obtained laminated polyester film had a hard coat layer thickness of 6 μm.

 This film showed strong adhesion without an easy-adhesion layer, and both transparency and interference fringes were good.

(Examples 9 to 10)
Example 1 is the same as Example 1 except that the polyester resin (B) of Example 1 is changed to the polyester resin B-2 containing an ultraviolet absorber and the mixing ratio with the polyester resin A-1 is changed as shown in Table 2. Thus, a laminated polyester film having a hard coat layer laminated thereon was produced.
This film was excellent in adhesiveness and wear resistance, had almost no interference fringes, and was excellent in light resistance.

 The film of the present invention is a hard coat film having excellent adhesion to the hard coat layer, almost no interference fringes, and excellent light resistance, and is used for antireflection films for displays such as liquid crystal and plasma. It is useful as a substrate film for substrates, touch panels, window coverings, solar cell members, nameplates and the like.

It is the wavelength / reflectance graph which showed the waviness amplitude of the reflectance.

Claims (3)

It consists of at least two types of polyester resins having different ΔTcg (cold crystallization temperature-glass transition temperature), one of which consists of a polyester (A) having a ΔTcg of 55 ° C. or less and a polyester (B) having a ΔTcg greater than 55 ° C. A laminated polyester film in which a hard coat layer is laminated on a polyester base film,
The average waviness reflectance width of the waviness curve of the reflectance at a wavelength of 400 to 600 nm measured from the hard coat layer side is 2% or less,
And the laminated polyester film characterized by having a haze of 3% or less. The laminated polyester film according to claim 1, wherein no adhesive layer is interposed at the interface between the polyester film and the hard coat layer. The laminated polyester film according to claim 1 or 2, wherein the polyester film contains an ultraviolet absorber.

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