JP2008266392A - Laminated polyester film for antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated polyester film for an antireflection film effective for improving the highlight contrast of a display in the case of placing at the outermost surface of an electronic display such as a plasma display, and having sufficient heat-resistance in the case of using in a film-type optical filter. <P>SOLUTION: The laminated polyester film for an antireflection film is a laminated polyester film composed of at least three layers and having coating layers formed in a film-production process on both surfaces of a film, contains a light absorber and an ultraviolet absorber in the inner layer, has an average light transmittance of 25-80% at a light wavelength of 400-650 nm, a light transmittance of ≤5.0% at a light wavelength of 380 nm, and a coating amount of 0.001-0.05 g/m<SP>2</SP>on one coating layer, and contains 10-50 wt.% crosslinking resin in the other coating layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laminated polyester film for an antireflection film that is suitably used for plasma display applications.

  In recent years, optical filters installed on the front of plasma displays, whose number has been increasing rapidly, are laminated structures of various functional layers such as an electromagnetic shielding layer, a near infrared shielding layer, an image quality adjustment layer (neon cut layer), and an impact resistant layer. However, an antireflection film is installed on the outermost surface.

As a base material for the antireflection film, a polyester film is mainly used from the viewpoints of transparency, dimensional stability, mechanical properties, heat resistance, electrical properties, gas barrier properties, chemical resistance, cost, and the like. The antireflection film is usually obtained by laminating a high refractive index layer and a low refractive index layer on a polyester film substrate on which an active energy ray-curable resin layer is coated.
The optical filter is usually designed so that its luminous transmittance is about 40%. This is to improve the contrast in bright environments (light contrast). After reducing the luminous transmittance, the ambient light from fluorescent lamps passes through the optical filter and is reflected on the surface of the plasma display panel. The amount of reflected light that passes through the optical filter and exits to the viewing side is reduced. Note that the value of the luminous transmittance tends to decrease year by year as the luminance of the plasma display panel increases.

  As a technique for reducing the luminous transmittance of the optical filter, a method in which a light absorber such as a dye or a pigment is blended in an adhesive or an adhesive, a method of blending in a polymer resin and a coating on the surface of a plastic film However, among these, the method of coating as a coating film is widely adopted because the heat resistance and dispersibility of the light absorber are not strict.

  However, these methods have a problem that the ambient light is reflected at the layer interface existing before the ambient light reaches the light absorber layer, and the light absorber cannot effectively exhibit its effectiveness. It was.

  In recent years, plasma displays have not been made of tempered glass that has been used as a support for optical filters in order to achieve further thinning, weight reduction, productivity improvement, and cost reduction of the entire plasma display. Plasma displays using a film-type optical filter that directly attaches the laminated film to the plasma display are becoming mainstream. As the antireflection film mounted on the film type optical filter, an antireflection / near infrared shielding composite film in which a near infrared shielding layer is coated on the back surface of the antireflection layer is usually used to reduce the layer structure. In a plasma display using a glass-type optical filter, an air layer exists between the optical filter and the plasma display. However, since a film-type optical filter is directly attached to the plasma display panel, heat is radiated directly from the plasma display panel. Heat is directly transferred to each functional layer, and high heat resistance is required for each functional layer.

However, the antireflection film prepared by the conventional method does not have sufficient heat resistance, and in particular, the peeling of the interface accompanying the decrease in adhesion after the heat test between the polyester film coating layer and the near infrared shielding layer, and the accompanying near infrared shielding. There is a problem that the layer is cracked, and swelling, turbidity, etc. due to moisture absorption in the peeled portion occur.
JP 2001-118530 A JP 2003-82127 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is to provide a laminated polyester film that can be suitably used as a base material for an antireflection film, specifically, a plasma display or the like. Provided is a laminated polyester film for an antireflection film that improves the bright contrast of the display when placed on the outermost surface of the electronic display and has sufficient heat resistance even when mounted on a film type optical filter. There is.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the use of a laminated polyester film having a specific configuration can easily solve the above-described problems, and have completed the present invention.

That is, the gist of the present invention is a laminated polyester film composed of at least three layers having a coating layer provided on both sides of the film provided in the film production process, and contains a light absorber and an ultraviolet absorber in the inner layer, The average value of the light transmittance at a light wavelength of 400 to 650 nm is 25 to 80%, the light transmittance at a light wavelength of 380 nm is 5.0% or less, and the coating amount of one coating layer is 0.001 to 0.00. It exists in the range of 05 g / m < ² >, It exists in the laminated polyester film for anti-reflective films characterized by containing 10 to 50weight% of crosslinking agent resin in another coating layer.

Hereinafter, the present invention will be described in more detail.
The term “laminated polyester film” as used in the present invention refers to a film in which all layers are extruded by a co-extrusion method in which all layers are co-extruded from a die and then heat-set as necessary. Hereinafter, a film having a three-layer structure will be described as the laminated polyester film, but the laminated polyester film of the present invention is not limited to the three-layer polyester film as long as the purpose is satisfied, and may be a multilayer of three or more layers. Good.

  The polyester used for the polyester film in the present invention refers to a polyester obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Representative polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), and the like. In the present invention, a third component other than the main component may be contained as long as it does not significantly affect the transparency, haze, and mechanical strength.

  The polyester in the present invention is a conventionally known method, for example, a method of directly obtaining a low-polymerization degree polyester by reaction of a dicarboxylic acid and a diol, or a lower alkyl ester of a dicarboxylic acid and a diol reacted with a conventionally known transesterification catalyst. Then, it can obtain by the method of performing a polymerization reaction in presence of a polymerization catalyst. As the polymerization catalyst, a known catalyst such as an antimony compound, a germanium compound, or a titanium compound may be used. Preferably, the amount of the antimony compound is zero or antimony is reduced to 100 ppm or less to reduce film dullness. .

  The outermost layer constituting the laminated polyester film of the present invention is a layer constituting two exposed surfaces immediately after being extruded from the die, and the other layers are referred to as inner layers. The viscosity (IV) of the polyester composition constituting the inner layer and the outermost layer is usually 0.52 to 0.75, preferably 0.55 to 0.70, and more preferably 0.58 to 0.67. When the IV value is less than 0.52, heat resistance and mechanical strength, which are excellent characteristics of polyester when used as a film, may be inferior. Moreover, when IV value exceeds 0.75, there exists a tendency for a load to become large too much at the extrusion process at the time of polyester film manufacture, and there exists a possibility that productivity may fall.

  The thickness of the polyester film of the present invention is not particularly limited as long as it can be formed as a film, but is usually 9 to 300 μm, preferably 25 to 250 μm, and more preferably 50 to 188 μm. The thickness of the outermost layer of the film of the present invention is preferably a thickness of only one side and is 0.5 μm or more and ¼ or less of the total thickness. If the thickness is less than 0.5 μm, the light absorber and UV absorber contained in the inner layer bleed out to the film surface due to the heat history during processing, etc., causing contamination of the production line and an increase in the amount of foreign matter on the film surface. May be seen. On the other hand, when it is thicker than 1/4 of the total thickness, the concentration of the layer containing the light absorber and the ultraviolet absorber increases, resulting in turbidity and delamination. In addition, the amount of lubricant particles blended in the outermost layer is increased for improving the film winding property, so that the haze value is increased and the transparency of the film tends to be deteriorated.

  In the film of the present invention, the average value (Tave) of light transmittance at a light wavelength of 400 to 650 nm is in the range of 25 to 80%, preferably 40 to 75%, and more preferably 50 to 70%. If Tave is less than 25%, an image projected from the plasma display when it is installed on the outermost surface of the plasma display optical filter becomes too dark. On the other hand, if Tave is larger than 80%, the effect of improving the contrast in a bright place is reduced, which is not preferable.

  In the film of the present invention, it is preferable that the Tave and the maximum value (Tmax) and the minimum value (Tmin) of the light transmittance at a light wavelength of 400 to 650 nm satisfy the following formulas (1) and (2), more preferably. (Tmax-Tave) and (Tave-Tmin) are within 7%, particularly preferably within 5%. If these values are greater than 10%, the film may be colored. In particular, when the color is changed to red, the quality of the plasma display is deteriorated, which may cause a practical problem.

Tmax−Tave ≦ 10% (1)
Tave−Tmin ≦ 10% (2)

  A light absorber is contained in at least one of the inner layers of the laminated film of the present invention. The type of the light absorber to be contained is not particularly limited as long as it has heat resistance that can withstand the melting step during the production of the polyester film and is excellent in dispersibility in the polyester. Examples of the dye include anthraquinone, heterocyclic, perinone, and quinoline dyes. Examples of organic pigments include phthalocyanine, perinone, isoindolinone, and pyrrole pigments. In addition, an inorganic pigment can also be contained for color matching as long as the transparency is not deteriorated.

  These light absorbers are preferably used in a suitable mixture of several kinds so as to be within the aforementioned light transmittance range. Although it does not specifically limit as content in raw material polyester as long as the objective of this invention is satisfy | filled, The range of 0.001 to 10 weight% is preferable. When the content is less than 0.001% by weight, it may be difficult to control the uniform dispersibility of the light absorber in the film. When the content exceeds 10% by weight, the concentration of the light absorber increases and the light absorption is increased. Aggregation of the agent may easily occur. Moreover, you may add antioxidant, a stabilizer, a light stabilizer, a flame retardant, an antistatic agent, a thickener, a lubricant, a plasticizer etc. as needed.

  The film of the present invention contains an ultraviolet absorber in the inner layer, and the content thereof is usually 0.01 to 10% by weight, preferably 0.3 to 1.8% by weight. When the content of the ultraviolet absorber is less than 0.01% by weight, the inner compound is deteriorated through the polyester film rather than the side to which the ultraviolet ray hits due to the ultraviolet rays transmitted through the polyester film. On the other hand, even if it contains an ultraviolet absorber in an amount exceeding 10.0% by weight, the effect of preventing the deterioration of the inner compound through the polyester film is saturated rather than the side that is exposed to ultraviolet rays. Ultraviolet absorbers bleed out on the surface, and there is a risk of reduced adhesiveness, deteriorated surface characteristics, and the like.

  The film according to the present invention has a light transmittance (Tuv) at a light wavelength of 380 nm of 5.0% or less, more preferably 2.0% or less, and still more preferably 1.0% or less. When Tuv is larger than 5.0%, it cannot be said that it is sufficient to prevent the inner compound from being deteriorated through the polyester film by the ultraviolet rays transmitted through the polyester film rather than the side to which the ultraviolet rays hit.

  The ultraviolet absorber used in the present invention may be an ultraviolet absorber that can be contained in the polyester. For example, a triazine compound, a benzophenone compound, a benzotriazole compound, a salicylate compound, a cyanoacrylate compound, Examples include benzoxazine compounds and cyclic imino ester compounds. Among these, triazine compounds, benzophenone compounds, and benzoxazine compounds are preferable because of their good compatibility with polyesters.

  In the laminated polyester film of the present invention, an active energy ray-curable resin layer is usually provided on the surface on which the antireflection layer is provided in order to improve surface hardness. Moreover, it is common to provide a near-infrared shielding layer on the surface opposite to the surface on which the antireflection layer is provided. In this case, since the polyester film is generally inactive, the adhesiveness is poor, and in order to improve the adhesiveness with the active energy ray-curable resin layer and the near-infrared shielding layer, the coating for improving the adhesiveness is applied. It is also necessary to provide a layer beforehand.

  As a method for forming such a coating layer, a so-called in-line coating method in which coating is performed before the transverse stretching step (before completion of orientation crystallization) and drying in a tenter is preferable. Moreover, you may perform various coatings by offline coating after manufacture of a laminated film as needed. Such coating is performed on both the surface on which the active energy ray-curable resin layer is provided and the surface on which the near-infrared shielding layer is provided. The coating material may be either water-based and / or solvent-based in the case of off-line coating. preferable.

  In the laminated polyester film of the present invention, when the active energy ray curable resin layer and the antireflection layer are laminated on the coating layer, for improving the antireflection performance and transparency, the active energy ray curable resin layer and the near infrared ray It is also possible to use a binder resin in order to improve the adhesion with the shielding layer.

  The “binder resin” used in the present invention is a number average molecular weight (measured by gel permeation chromatography (GPC) measurement) according to a polymer compound safety evaluation flow scheme (sponsored by the Chemical Substances Council in November 1985). Mn) is a high molecular compound having a molecular weight of 1000 or more and has a film forming property.

  Specific examples of the binder resin include polyester resin, acrylic resin, urethane resin, polyvinyl, polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, and starches. Polyester resin, acrylic resin, and urethane resin are more preferably used in terms of improving adhesion with the active energy ray-curable resin layer.

  Melamine-based resins, epoxy-based resins, and oxazoline-based resins are generally used as the cross-linking agent resin, but melamine-based resins are particularly preferable in terms of coating properties and durable adhesiveness. The melamine-based resin is not particularly limited, but melamine, a methylolated melamine derivative obtained by condensing melamine and formaldehyde, a compound partially or completely etherified by reacting methylolated melamine with a lower alcohol, And a mixture thereof or a compound obtained by substituting a part or all of melamine with urea can be used.

  The melamine resin may be either a monomer or a condensate composed of a dimer or higher multimer, or a mixture thereof. As the lower alcohol used for the etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like can be preferably 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 resin, a methylol group type melamine resin, or a methylol type methyl group. A melamine resin or a fully alkyl methylated melamine resin can be used. Of these, methylolated melamine resins are most preferred. Further, an acidic catalyst such as p-toluenesulfonic acid can be used to promote thermal curing of the melamine-based crosslinking agent.

  The blending amount of the crosslinking agent resin in the coating agent is in the range of 10 to 50% by weight, preferably 20 to 40% by weight on the surface on which the near infrared ray shielding layer is provided. When the blending amount of the crosslinking agent resin is less than 10% by weight, the adhesion after the durability test cannot be sufficiently exhibited, and when it exceeds 50% by weight, sufficient initial adhesion is not exhibited. In the surface which provides an antireflection layer, it is 1-50 weight% normally, Preferably it is the range of 5-30 weight%. When the blending amount of the crosslinking agent resin is less than 1% by weight, the durable adhesiveness may not be sufficiently exhibited, and the effect of improving the solvent resistance tends to be insufficient. There is a risk that the good adhesion will not be demonstrated.

  In the present invention, it is preferable to contain inorganic particles or organic particles in the coating layer in order to further improve the slipperiness, adhesion and the like. The amount of the particles in the coating agent is usually 0.5 to 10% by weight, preferably 1 to 5% by weight. When the blending amount is less than 0.5% by weight, the blocking resistance may be insufficient. When the blending amount exceeds 10% by weight, the transparency of the film is hindered and the sharpness of the image tends to be lowered.

  Examples of inorganic particles include silica, alumina, zirconium oxide, kaolin, talc, calcium carbonate, titanium oxide, barium oxide, carbon black, molybdenum sulfide, and antimony oxide. Among these, silica is easy to use because it is inexpensive and has various particle sizes. Examples of the organic particles include polystyrene or polyacrylate polymethacrylate in which a crosslinked structure is achieved by a compound (for example, divinylbenzene) containing two or more carbon-carbon double bonds in one molecule.

  The above inorganic particles and organic particles may be surface-treated. Examples of the surface treatment agent include a surfactant, a polymer as a dispersant, a silane coupling agent, a titanium coupling agent, and the like. The content of the particles in the coating layer is preferably 10% by weight or less, more preferably 5% by weight or less as an appropriate addition amount that does not impair the transparency.

  The coating layer may contain an antistatic agent, an antifoaming agent, a coating property improving agent, a thickener, an antioxidant, an ultraviolet absorber, a foaming agent, a dye, a pigment, and the like. As long as water is the main medium, the coating agent may contain a small amount of an organic solvent for the purpose of improving dispersion in water or improving the film forming performance. It is necessary to use the organic solvent as long as it is soluble in water. Examples of the organic solvent include aliphatic or alicyclic alcohols such as n-butyl alcohol, n-propyl alcohol, isopropyl alcohol, ethyl alcohol, and methyl alcohol, glycols such as propylene glycol, ethylene glycol, and diethylene glycol, n-butyl cellosolve, Glycol derivatives such as ethyl cellosolve, methyl cellosolve, propylene glycol monomethyl ether, ethers such as dioxane and tetrahydrofuran, esters such as ethyl acetate and amyl acetate, ketones such as methyl ethyl ketone and acetone, amides such as N-methylpyrrolidone Can be mentioned. These organic solvents may be used in combination of two or more as required.

  As a coating method of the coating agent, for example, a reverse roll coater, a gravure coater, a rod coater, an air doctor coater or other coating apparatus as shown in Yuji Harasaki's book, “Coating Method” published in 1979 by Tsuji Shoten is used. can do. In order to improve the coating property and adhesiveness of the coating agent to the film, the film may be subjected to chemical treatment or discharge treatment before coating. In order to further improve the surface characteristics, a discharge treatment may be performed after the coating layer is formed.

Further, the coating amount of the coating layer is in the range of 0.001 to 0.05 g / m ² as the weight after final drying on the surface on which the antireflection layer is usually provided, preferably 0.005 to 0.03 g / m ² or less. When the coating amount is less than 0.001 g / m ² , the adhesiveness with the active energy ray-curable resin layer provided on the coating layer cannot be sufficiently satisfied. On the other hand, when the coating amount exceeds 0.05 g / m ² , there is mutual interference between the reflected light at the interface between the coating layer and the polyester film and the reflected light at the interface between the coating layer and the active energy ray curable resin layer. The wavelength region that occurs is the visible light region. That is, when there is slight coating thickness unevenness of the coating layer, the wavelength distribution of the reflected light intensity of the film is generated in the visible light region, which is not preferable because it causes coloring of the reflected light. In particular, where there are particles that are included for the purpose of improving slipperiness and adhesion, unevenness in the thickness of the coating layer is likely to occur. Coloring is not preferable.
In the face of near-infrared absorption layer it is usually provided, 0.001~0.3g / ^{m 2} or less as a normal weight after the final drying, more preferably in the range of 0.005~0.2g / ^{m 2.} When the coating amount is less than 0.001 g / m ² , there is a possibility that the adhesiveness with the near-infrared shielding layer provided on the coating layer cannot be sufficiently satisfied. On the other hand, when the coating amount exceeds 0.3 g / m ² , problems such as a decrease in slipperiness may occur.

  Moreover, as a hardening component of the active energy ray hardening resin layer formed on the coating layer on the surface on which the antireflection layer of the film of the present invention is provided, unsaturated polyester resin, acrylic, addition polymerization, thiol / acrylic hybrid Cationic polymerization systems, hybrid systems of cationic polymerization and radical polymerization, and the like can be used. Among these, acrylic curing components are preferable from the viewpoints of curability, scratch resistance, surface hardness, flexibility, and durability.

  Said acrylic hardening component contains the acrylic oligomer and reactive diluent as an active energy ray polymerization component. And a photoinitiator, a photosensitizer, and a modifier are contained as needed. Typical examples of the acrylic oligomer include an oligomer in which a reactive acryloyl group or methacryloyl group is bonded to an acrylic resin skeleton. Examples of other acrylic oligomers include polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, polyether (meth) acrylate, silicone (meth) acrylate, polybutadiene (meth) acrylate, and the like. Furthermore, an oligomer in which an acryloyl group or a methacryloyl group is bonded to a rigid skeleton such as melamine, isocyanuric acid, and cyclic phosphazene can be given.

  The reactive diluent serves as a solvent for the coating process as a coating medium, and also has a group that reacts with a polyfunctional or monofunctional acrylic oligomer. It becomes. Specific examples of reactive diluents 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, ethylene glycol (meth) acrylate, propylene glycol (meth) acrylate, (meth) acryloyloxypropyltriethoxysilane, (meth) acryloyloxy And propyltrimethoxysilane.

  Examples of the photopolymerization initiator include 2,2-ethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, dibenzoyl, benzoin, benzoin isopropyl ether, p-chlorobenzophenone, p-methoxy. Examples include benzophenone, Michler's ketone, acetophenone, 2-chlorothioxanthone, anthraquinone, phenyl disulfide, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone.

  Examples of the photosensitizer include tertiary amines such as triethylamine, triethanolamine and 2-dimethylaminoethanol, alkylphosphine such as triphenylphosphine, and thioethers such as β-thiodiglycol. Examples of the modifier include coating property improvers, antifoaming agents, thickeners, inorganic particles, organic particles, lubricants, organic polymers, dyes, pigments, stabilizers, antistatic agents, and the like. These are used in the range which does not inhibit the reaction by an active energy ray, and can improve the characteristic of an active energy ray hardening resin layer according to a use. An organic solvent can be blended with the composition of the active energy ray-curable resin layer in order to improve workability during coating and control the coating thickness.

  The active energy ray-curable resin layer is formed by applying a curing resin composition to the surface of the coating layer and then irradiating the active energy ray to crosslink and cure. As active energy rays, ultraviolet rays, visible rays, electron beams, X-rays, α rays, β rays, and γ rays can be used. Irradiation of active energy rays is usually performed from the coating layer side, but may be performed from the film surface side in order to improve the adhesion to the film, and further a reflective plate capable of reflecting active energy rays is provided on the film surface side. It may be provided.

  The thickness of the active energy ray-curable resin layer is usually 0.5 to 15 μm, preferably 1 to 10 μm. When the thickness of the cured resin layer is less than 0.5 μm, the surface hardness may be insufficient. When the thickness exceeds 15 μm, the cured resin layer has a large cure shrinkage and the film curls toward the cured resin layer. There are things to do. In the present invention, the surface hardness of the cured resin layer side is usually H or higher, preferably 2H or higher. If it is less than H, the scratch resistance is insufficient.

  The near-infrared shielding layer formed on the opposite side of the surface of the film of the present invention provided with an antireflection layer is usually formed by applying and drying a binder resin containing a near-infrared shielding agent and diluted with a solvent. The The paint contains coating improvers, antifoaming agents, thickeners, inorganic particles, organic particles, lubricants, organic polymers, dyes, pigments, stabilizers, antistatic agents, etc. as necessary. . As a coating method, a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, or any other coating device as shown in the above-mentioned “Coating Method” published by Yuji Harasaki and published by Tsuji Shoten in 1979 is used. be able to.

  As the near-infrared shielding agent, any dye having absorption in the near-infrared region may be used. Nickel complex compounds, copper compounds, tungsten compounds, indium tin oxide, antimony tin oxide, ytterbium phosphate, and the like. These near-infrared shielding agents may be used in combination of two or more as required.

  Specific examples of the binder resin used for the near-infrared shielding layer usually include polyester resin, acrylic resin, urethane resin, melamine resin, polycarbonate resin, polyolefin resin, polyvinyl resin, polyvinyl alcohol resin, and the like. From the viewpoints of dispersibility, transparency, durability, etc., polyester resins, acrylic resins, and polycarbonate resins are preferred.

  Examples of the solvent usually include halogen-based, alcohol-based, ketone-based, ester-based, aliphatic hydrocarbon-based, aromatic hydrocarbon-based, and ether-based solvents. These solvents may be used in combination of two or more as required.

  The thickness of the near infrared shielding layer is usually in the range of 0.5 to 15 μm, preferably 1 to 10 μm. When the thickness of the near-infrared shielding layer is less than 0.5 μm, the concentration of the near-infrared shielding agent is increased and the durability deteriorates due to the interaction between the near-infrared shielding agents. Tends to be insufficient, the residual solvent amount in the near infrared absorption layer increases and the durability deteriorates, and the strength of the coating layer may be insufficient.

  You may mix | blend particle | grains with the outermost layer of the lamination | stacking polyester layer in this invention for the main purpose of providing lubricity. 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 thereof include particles of magnesium silicon oxide, kaolin, aluminum oxide, titanium oxide and the like. Further, the heat-resistant organic particles described in JP-B-59-5216, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like. Furthermore, 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.

  On the other hand, 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 | limiting in particular also about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

  Further, the average particle size of the particles used is usually preferably 0.01 to 5 μm. If the average particle size is less than 0.01 μm, the particles tend to aggregate and the dispersibility may be insufficient. On the other hand, if the average particle size exceeds 5 μm, the surface roughness of the film becomes too rough and transparent. There is a risk that the sex will be impaired.

  Furthermore, the particle content in the polyester is usually in the range of 0.0003 to 1.0% by weight, preferably 0.0005 to 0.5% by weight, based on the weight of the entire film. When the particle content is less than 0.0003 wt%, the slipperiness of the film may be insufficient. On the other hand, when the content exceeds 1.0 wt%, the transparency of the film is insufficient. There are cases.

  The method for adding particles to the polyester is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage for producing the polyester, but the polycondensation reaction may proceed preferably after the esterification stage or after the transesterification reaction. Also, 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. It is done by methods.

  In addition to the above-mentioned particles, conventionally known antioxidants, heat stabilizers, lubricants, antistatic agents, fluorescent brighteners, and the like can be added to the polyester film in the present invention as necessary.

  In the film of the present invention, the film haze is usually in the range of 0 to 3.0%, preferably 0 to 1.5%, more preferably 0 to 1.2%, and particularly preferably 0 to 1.0%. %. The film of the present invention is widely used in optical applications because of its excellent transparency. However, when the film haze exceeds 3.0%, the image displayed on the plasma display, the distortion of color, and the blur It may be a cause.

  In the polyester film of the present invention, various functional layers such as an image quality correction layer and an electromagnetic wave shielding layer may be laminated on the near infrared shielding layer.

  According to the present invention, it is possible to provide a laminated polyester film for an antireflection film that improves the bright place contrast of an electronic display and has sufficient heat resistance even when mounted on a film type optical filter. Industrial value is extremely high.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The measuring method used in the present invention is as follows.

(1) Viscosity (IV)
1 g of the polymer was dissolved in 100 ml of a mixed solvent of phenol / tetrachloroethane = 1/1 (weight ratio) and measured at 30 ° C.

(2) Lamination thickness of film After fixing a small piece of film with an epoxy resin, it was cut with a microtome, and the cross section of the film was observed with an optical microscope photograph. Of the cross section, two interfaces are observed substantially parallel to the film surface. The distance between the two interfaces and the film surface was measured from 10 photos, and the average thickness was obtained.

(3) Average particle diameter (d ₅₀ : μm)
The particle size was measured by a sedimentation method based on Stokes' resistance law using a Shimadzu centrifugal sedimentation type particle size distribution analyzer SA-CP3 type. The average particle diameter was determined by using a value of 50% of integration (volume basis) in the equivalent spherical distribution of particles obtained by measurement.

(4) Light transmittance Using a spectrophotometer (UV3100PC, manufactured by Shimadzu Corporation), the light transmittance is measured continuously in a region where the scanning speed is low, the sampling pitch is 1 nm, and the light wavelength is 350 to 800 nm using a halogen lamp light source. From the measurement results, the maximum value (Tmax) and minimum value (Tmin) of the light transmittance at a light wavelength of 400 to 650 nm and the light transmittance (Tuv) at a light wavelength of 380 nm were read. About the average value (Tave) of the light transmittance, it computed from the above-mentioned measurement result by the arithmetic mean.

(5) Film haze Film haze was measured with an integrating sphere turbidimeter “NDH-300A” manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS-K-7105.

(6) Coating amount Cut out the film into 10 pieces of 100 mm x 100 mm, wipe the surface to measure the coating amount with a cloth soaked with a mixed organic solvent of methyl ethyl ketone / toluene = 1/1, and calculate the square meter from the weight difference before and after wiping. The amount of coating (g / m ² ) was calculated in terms of per unit.

(7) Film color The film was visually observed under a three-wavelength light emitting fluorescent lamp, and the color was visually evaluated.

(8) Local coloring of the antireflection layer A perfluoro (2-butyltetrahydrofuran) solution of a polymer of perfluorobutenyl vinyl ether is used on the active energy ray-curable resin layer, and the coating thickness after drying is used. Was applied by a microgravure method so that the thickness was 100 nm, dried at 120 ° C. for 10 minutes, and an antireflection layer was laminated. The obtained antireflection film was evaluated by visually observing interference unevenness under a three-wavelength light emitting fluorescent lamp. The judgment criteria are as follows.
○: No local coloring of the reflected color ×: Local coloring of the reflected color can be confirmed

(9) UV light resistance The anti-reflection / near-infrared shielding composite film in which the anti-reflection layer and the near-infrared shielding layer are formed is used at 63 ± 3 ° C. using an ultraviolet long life fade meter (FAL-3 type) manufactured by Suga Test Instruments. Ultraviolet rays were irradiated from the antireflection layer side for 500 hours. Before and after UV irradiation, the difference in light transmittance (ΔT ₁₁₀₀ ) of the sample with a light wavelength of 1100 nm was used. The smaller the value of ΔT _1100, the less the near-infrared absorbing dye is deteriorated, indicating that the UV light resistance is better. Shimadzu UV3100PC was used for measurement of light transmittance at a light wavelength of 1100 nm. The criteria for light resistance are as follows.
○: ΔT ₁₁₀₀ ≦ 1.0
X: 1.0 <ΔT ₁₁₀₀

(10) Bright place contrast An electromagnetic wave shielding mesh (line width: 10 μm, line pitch: 250 μm) is bonded to the near infrared shielding layer side of the antireflection / near infrared shielding composite film in which the antireflection layer and the near infrared shielding layer are formed. An optical filter was used. This optical filter is bonded to the front of a plasma display panel (W42-P5000, manufactured by Hitachi, Ltd.) from which a commercially available optical filter has been removed, through an adhesive layer. Half of the display is black and the other half is white. Then, the contrast difference of the interface was visually evaluated under a three-wavelength light emitting fluorescent lamp. The criteria for determining the bright place contrast are as follows.
A: The contrast difference between the white display portion and the black display portion is high and the visibility is excellent. B: The white display portion is excellent in luminance and very bright, but the black display portion is white and the visibility is poor. C: Black Although the display is sufficiently dark, the brightness of the white display is low and the visibility is poor

(11) Initial adhesiveness with active energy ray-curing resin layer and adhesiveness after heat test Acrylic hard coat agent "Shikou (manufactured by Nippon Synthetic Chemical Industry)" is diluted with a mixed solvent of toluene and methyl ethyl ketone and cured. The film was coated on the side where the antireflection layer of the film was provided by a reverse gravure method so that the thickness afterwards was 3 μm. Next, after drying at 110 ° C. for 1 minute to remove the solvent, the active energy ray-cured resin layer was formed by UV curing with a high-pressure mercury lamp at an output of 120 W / cm, an irradiation distance of 15 cm, and a line speed of 10 m / min. For the evaluation of initial adhesion, immediately after curing, the layer is cross-cut so that there are 100 grids in a 1-inch width, and immediately, the same part is subjected to a rapid peel test with cello tape (registered trademark) three times. And evaluated by the peeled area. For the evaluation of adhesiveness after the heat resistance test, after forming an active energy ray-cured resin layer and exposing it to an environment of 90 ° C. for 1000 hours with a small environmental tester, a rapid peel test using the above-mentioned cello tape (registered trademark). And evaluated by the peeled area. The judgment criteria are as follows.
A: Number of cross-cuts = 0
○: 1 ≦ Number of cross cuts ≦ 20
×: 21 ≦ Number of cross-cuts peeled

(12) Initial adhesion to near-infrared shielding layer and adhesion after heat test Near-infrared absorbing dye “CIR-1085 (manufactured by Nippon Carlit)” and resin binder “Optrez OZ1100 (Hitachi) with a mixed solvent of toluene and methyl ethyl ketone (Made by Kasei Kogyo Co., Ltd.) ”is blended so that the pigment weight (solid content concentration) is 6.2 parts by weight, and this is a microgravure system so that the thickness after drying is 6 μm on the side where the near infrared shielding layer is provided. And dried to form a near infrared shielding layer. For evaluation of initial adhesion, immediately after formation, the layer is cross-cut so that there are 100 grids in a 1-inch width, and immediately, a rapid peel test with cello tape (registered trademark) is performed three times at the same location. And evaluated by the peeled area. For the evaluation of adhesion after the heat resistance test, after forming a near-infrared layer, it was exposed to an environment of 90 ° C. for 1000 hours with a small environmental testing machine, and then a rapid peel test with the above-mentioned cello tape (registered trademark) was performed. Evaluation was based on the peeled area. The judgment criteria are as follows.
A: Number of cross-cuts = 0
○: 1 ≦ Number of cross cuts ≦ 20
×: 21 ≦ Number of cross-cuts peeled

Examples and Comparative Examples are shown below, and the production method of the polyester used for this is as follows.
<Manufacture of polyester>
<Method for producing polyester (A)>
Using 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol as starting materials, tetrabutoxy titanate as a catalyst in a reactor, the reaction start temperature is set to 150 ° C., and the reaction temperature is gradually increased as methanol is distilled off. It was 230 degreeC after the time. After 4 hours, the transesterification reaction was substantially completed, and then a polycondensation reaction was performed for 4 hours. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. After the start of the reaction, 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.

<Method for producing polyester (B)>
After preliminarily crystallizing the polyester (A) at 160 ° C., it was subjected to solid phase polymerization in a nitrogen atmosphere at a temperature of 220 ° C. to obtain a polyester (B) having an intrinsic viscosity of 0.75.

<Method for producing polyester (C)>
In the production method of polyester (A), 0.2 parts of silica particles having an average particle diameter of 1.6 μm dispersed in ethylene glycol were added, and the polycondensation reaction was stopped at a time corresponding to an intrinsic viscosity of 0.65. Polyester (C) was obtained using a method similar to the method for producing polyester (A). The obtained polyester (C) had an intrinsic viscosity of 0.65.

<Method for producing polyester (D)>
The polyester (A) was subjected to a twin screw extruder with a vent, and 2,2- (1,4-phenylene) bis [4H-3,1-benzoxazin-4-one] was used as a UV absorber in a concentration of 10% by weight. Then, the mixture was melt kneaded to form chips, and an ultraviolet absorbent master batch polyester (D) was prepared. The intrinsic viscosity of the obtained polyester (D) was 0.59.

<Method for producing polyester (E)>
Polyester (A) was subjected to a twin screw extruder with a vent, 2.0% by weight of Dairesin Red S manufactured by Mitsubishi Chemical, 1.3% by weight of Viored D, 4.4% by weight of Blue H3G, and the same yellow. F was supplied to a concentration of 2.3% by weight, melt-kneaded to form chips, and a dye master batch polyester (E) was prepared. The intrinsic viscosity of the obtained polyester (E) was 0.60.

<Method for producing polyester (F)>
Polyester (A) was subjected to a vented twin-screw extruder, and Mitsubishi Chemical Diaresin Red S 4.0 wt%, Vio Red D 1.2 wt%, Blue H3G 2.8 wt%, and Yellow F was supplied at a concentration of 2.0% by weight, melted and kneaded to form chips, and a dye master batch polyester (F) was prepared. The intrinsic viscosity of the obtained polyester (F) was 0.60.

Examples of compounds constituting the coating layer are as follows.
<Water-based paint a: Polyester resin>
Water dispersion monomer composition of polyester resin copolymerized with the following composition: (acid component) terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene glycol / 1,4-butanediol / diethylene glycol = 56/40/4 // 70/20/10 (mol%)

<Water-based paint b: Acrylic resin>
Emulsion polymer of methyl methacrylate / ethyl acrylate / acrylonitrile / N-methylol methacrylamide = 45/45/5/5 (molar ratio) (emulsifier: anionic surfactant)

<Water-based paint c: Melamine compound>
Hexamethoxymethylmelamine

<Water-based paint d: inorganic particles>
Silica sol having an average particle diameter of 65 nm The solid content ratios of the above-mentioned various water-based paints of the coating liquids 1 to 3 applied before completion of orientation crystallization used in the following examples and comparative examples are as shown in Table 1 below. .

Example 1:
A mixed raw material obtained by mixing the above polyesters (B) and (C) at a ratio of 92.0% and 8.0%, respectively, is used as a raw material for the A layer, and polyesters (A), (D), and (E) are each 90 Each of the mixed raw materials mixed at a ratio of 0.7%, 8.0% and 1.3% was supplied to the two bent twin-screw extruders as the raw material for the B layer, and melted at 285 ° C. Coextruded with a layer configuration of two types and three layers (A / B / A) with the outermost layer (surface layer) as the intermediate layer and the B layer as the intermediate layer, extruded from the die, and the surface temperature was set to 40 ° C. using the electrostatic application adhesion method It cooled and solidified on the set cooling roll, and the unstretched sheet was obtained. Next, the film was stretched 3.4 times in the longitudinal direction at a film temperature of 81 ° C. using the roll peripheral speed difference, and then the coating liquid 1 was applied to both the surface on which the antireflection layer was provided / the surface on which the near-infrared shielding layer was provided. The film was stretched 4.0 times at 120 ° C in the transverse direction, heat-treated at 225 ° C, and then relaxed by 2% in the transverse direction through a cooling zone at 140 ° C to obtain a laminated polyester film having a thickness of 100 µm. It was. The thickness of each layer of the obtained film was 5/90/5 μm. The coating amount of the surface providing the antireflection layer at 0.0082 g / ^{m 2,} the coating amount of the surface providing the near infrared ray shielding layer was 0.145 g / ^{m 2.}

Example 2:
In Example 1, except that the raw material of layer B was a mixed raw material in which polyesters (A), (D), and (E) were mixed at 89.0%, 8.0%, and 3.0%, respectively. In the same manner as in Example 1, a 100 μm thick polyester film was obtained. The thickness of each layer of the obtained film was 5/90/5 μm. The coating amount on the surface on which the antireflection layer was provided was 0.0084 g / m ² , and the coating amount on the surface on which the near-infrared shielding layer was provided was 0.147 g / m ² .

Example 3:
In Example 1, except that the raw material of the B layer was a mixed raw material in which polyesters (A), (D), and (E) were mixed at 86.0%, 8.0%, and 6.0%, respectively. A polyester film having a thickness of 100 μm was obtained in the same manner as in Example 1. The thickness of each layer of the obtained film was 5/90/5 μm. The coating amount of the surface providing the antireflection layer at 0.0085 / ^{m 2,} the coating amount of the surface providing the near infrared ray shielding layer was 0.138 g / ^{m 2.}

Example 4:
In Example 1, except that the raw material of layer B was a mixed raw material in which polyesters (A), (D), and (E) were mixed at 91.3%, 8.0%, and 0.7%, respectively. A polyester film having a thickness of 100 μm was obtained in the same manner as in Example 1. The thickness of each layer of the obtained film was 5/90/5 μm. The coating amount of the surface providing the antireflection layer at 0.0082 g / ^{m 2,} the coating amount of the surface providing the near infrared ray shielding layer was 0.140 g / ^{m 2.}

Example 5:
In Example 1, except that the raw material of layer B was a mixed raw material in which polyesters (A), (D), and (F) were mixed at 90.7%, 8.0%, and 1.3%, respectively. A polyester film having a thickness of 100 μm was obtained in the same manner as in Example 1. The thickness of each layer of the obtained film was 5/90/5 μm. The coating amount of the surface providing the antireflection layer at 0.0079 g / ^{m 2,} the coating amount of the surface providing the near infrared ray shielding layer was 0.142 g / ^{m 2.} When the antireflection film obtained using this film was visually confirmed, its color was slightly red.

Comparative Example 1:
In Example 1, except that the raw material of layer B was a mixed raw material in which polyesters (A), (D), and (E) were mixed at 91.9%, 8.0%, and 0.1%, respectively. A polyester film having a thickness of 100 μm was obtained in the same manner as in Example 1. The thickness of each layer of the obtained film was 5/90/5 μm. The coating amount of the surface providing the antireflection layer at 0.0081 g / ^{m 2,} the coating amount of the surface providing the near infrared ray shielding layer was 0.142 g / ^{m 2.}

Comparative Example 2:
In Example 1, except that the raw material of layer B was a mixed raw material in which polyesters (A), (D), and (E) were mixed at 85.0%, 8.0%, and 7.0%, respectively. A polyester film having a thickness of 100 μm was obtained in the same manner as in Example 1. The thickness of each layer of the obtained film was 5/90/5 μm. The coating amount on the surface on which the antireflection layer was provided was 0.0078 g / m ² , and the coating amount on the surface on which the near-infrared shielding layer was provided was 0.144 g / m ² .

Comparative Example 3:
In Example 1, except that the raw material of layer B was a mixed raw material in which polyesters (A), (D), and (E) were mixed at 95.4%, 3.3%, and 1.3%, respectively. A polyester film having a thickness of 100 μm was obtained in the same manner as in Example 1. The thickness of each layer of the obtained film was 5/90/5 μm. The coating amount of the surface providing the antireflection layer at 0.0081 g / ^{m 2,} the coating amount of the surface providing the near infrared ray shielding layer was 0.138 g / ^{m 2.}

Comparative Example 4:
In Example 1, a thickness of 100 μm was obtained in the same manner as in Example 1 except that the coating amount applied to the surface on which the antireflection layer was applied was 0.0004 g / m ^{2 in} terms of the coating amount after drying. A polyester film was obtained. The thickness of each layer of the obtained film was 5/90/5 μm. The coating amount on the surface on which the antireflection layer was provided was 0.0004 g / m ² , and the coating amount on the surface on which the near infrared ray shielding layer was provided was 0.140 g / m ² .

Comparative Example 5:
In Example 1, a thickness of 100 μm was obtained in the same manner as in Example 1 except that the coating amount applied to the surface on which the antireflection layer was applied was 0.08 g / m ^{2 in} terms of the coating amount after drying. A polyester film was obtained. The thickness of each layer of the obtained film was 5/90/5 μm. The coating amount on the surface on which the antireflection layer was provided was 0.0851 g / m ² , and the coating amount on the surface on which the near-infrared shielding layer was provided was 0.141 g / m ² .

Comparative Example 6:
A polyester film having a thickness of 100 μm was obtained in the same manner as in Example 1 except that the coating solution 2 applied to the surface on which the near-infrared shielding layer was provided was changed to the coating solution 2. The thickness of each layer of the obtained film was 5/90/5 μm. The coating amount on the surface on which the antireflection layer was provided was 0.0081 g / m ² , and the coating amount on the surface on which the near infrared shielding layer was provided was 0.141 g / m ² .

Comparative Example 7:
A polyester film having a thickness of 100 μm was obtained in the same manner as in Example 1 except that the coating solution 3 applied to the surface on which the near infrared shielding layer was provided was changed to the coating solution 3. The thickness of each layer of the obtained film was 5/90/5 μm. The coating amount of the surface providing the antireflection layer at 0.0083g / ^{m 2,} the coating amount of the surface providing the near infrared ray shielding layer was 0.145 g / ^{m 2.}

Comparative Example 8:
Supplied to a single bent twin-screw extruder using mixed raw materials in which polyesters (A), (C), and (E) are mixed in proportions of 91.0%, 8.0%, and 1.0%, respectively. Then, melt extrusion was performed, and the conditions of stretching and heat treatment were the same as in Example 1 to obtain a single layer film having a thickness of 100 μm. The obtained film had a thickness of 100 μm and was a film in which a light absorber was deposited on the film surface. For this reason, the coating amount and characteristics of the coating layer could not be measured accurately. In addition, after production of the film, contamination by the light absorber on the production line was confirmed.

  The characteristics of the polyester films obtained in Examples 1 to 5 and Comparative Examples 1 to 7 are collectively shown in Tables 2 to 4 below. It can be seen that a film satisfying the requirements of the present invention has high suitability for optical use.

  The film of the present invention can be suitably used, for example, for an antireflection film that is suitably used for plasma display applications.

Claims (1)

A laminated polyester film consisting of at least three layers, each having a coating layer provided in the film production process, containing a light absorber and an ultraviolet absorber in the inner layer, and transmitting light at a light wavelength of 400 to 650 nm. The average value of the rate is 25 to 80%, the light transmittance at a light wavelength of 380 nm is 5.0% or less, and the coating amount of one coating layer is in the range of 0.001 to 0.05 g / m ² . A laminated polyester film for an antireflection film, wherein the other coating layer contains 10 to 50% by weight of a crosslinking agent resin.