JP5014616B2 - Optical laminated polyester film - Google Patents

Description

  The present invention relates to a laminated polyester film for optics, and for example, a liquid crystal display (hereinafter abbreviated as LCD), a plasma display panel (hereinafter abbreviated as PDP), an organic electroluminescence (hereinafter abbreviated as organic EL). ), Etc., for a laminated polyester film suitable for optical applications such as for producing display members.

  Conventionally, an optical film having a polyester film as a substrate has been used for various optical applications including production of display members such as LCD, PDP, and organic EL. These optical films are required to have excellent transparency and visibility.

  These optical films are used by laminating surface functional layers such as a hard coat layer and an antireflection layer on a plastic film. As the plastic film, a transparent polyester film is generally used, and in order to improve the adhesion between the polyester film of the base material and the surface functional layer, an easily adhesive coating layer may be provided as an intermediate layer. It is common.

  As an antireflection film, generally, a high-refractive index layer and a low-refractive index layer are alternately laminated as a surface functional layer to prevent reflection of external light by utilizing a light interference phenomenon.

  In recent years, LCDs, PDPs, and other display materials have been required to have larger screens, higher image quality, and higher quality, and in response to this, there has been a demand for suppressing iris-like colors (interference unevenness) especially under fluorescent lamps. The level is getting higher. In addition, fluorescent lamps have become a three-wavelength type for daylight color reproducibility, and interference unevenness is more likely to occur. Furthermore, there is an increasing demand for simplification of the antireflection layer in order to achieve cost reduction and the like. Therefore, the optical design of the coating layer laminated on the polyester film has become important.

  On the other hand, as an application layer provided in order to improve adhesiveness with the surface functional layer laminated | stacked on a polyester film, a polyester resin, an acrylic resin, a urethane resin, etc. are mentioned.

  In the conventional resin coating layer as described above, the refractive index is fixed at around 1.50. Therefore, when designing an antireflection film, the antireflection performance is limited, and interference unevenness due to reflection of external light is remarkable. May occur. When a film in which interference unevenness due to reflection of external light is remarkably generated is used as a display member for LCD, PDP, organic EL, etc., various problems due to deterioration in visibility tend to become more apparent. In addition, the remarkable occurrence of interference unevenness not only deteriorates the visibility, but may also cause eye fatigue and health problems.

In order to reduce interference unevenness, in order to increase the refractive index of the coating layer, a conventional coating layer is provided which is formed from a coating solution mainly composed of a water-based polyester resin and a chelate or acylate compound of water-soluble titanium or zirconium. In the method, the adhesion with various surface functional layers to be laminated may not be sufficient. In addition, there is a method of increasing the refractive index of the coating layer by including a metal oxide having a high refractive index in the coating layer, but in this case, the transparency of the film is lowered and performance sufficient as an optical film is achieved. May not be possible.
JP-A-10-119215 JP 2000-246855 A Japanese Patent No. 3632044 JP 2004-54161 A

  The present invention has been made in view of the above-described circumstances, and the solution is to reduce various types of display components such as LCDs, PDPs, organic ELs, and other display members that have reduced interference unevenness due to external light reflection. An object of the present invention is to provide an optical laminated polyester film that can be suitably used for various optical applications in addition to the production of materials.

  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-mentioned problems, and have completed the present invention.

That is, the gist of the present invention is obtained by applying and drying a coating liquid containing a polyester resin, an epoxy compound having a bisphenol A structure, and a melamine compound on at least one side of a polyester film stretched in at least a uniaxial direction. The coating amount (after drying) has a coating layer in the range of 0.005 to 0.5 g / m ² , and the total amount of the epoxy compound having a bisphenol A structure and the melamine compound in the coating layer is a polyester resin. It exists in the range of 56-385 with respect to 100, exists in the laminated polyester film for optics.

Hereinafter, the present invention will be described in more detail.
The polyester film constituting the laminated polyester film in the present invention may have a single-layer structure or a laminated structure, and may have four or more layers as long as the gist of the present invention is not exceeded other than the two-layer or three-layer structure. It may be a multilayer, and is not particularly limited.

  The polyester used in the present invention may be a homopolyester or a copolyester. In the case of a homopolyester, those obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol are preferred. 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. Typical polyester includes polyethylene terephthalate and the like. On the other hand, the dicarboxylic acid component of the copolyester includes isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, p-oxybenzoic acid, etc.), etc. 1 type or 2 types or more are mentioned, As a glycol component, 1 type or 2 types or more, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 4-cyclohexane dimethanol, neopentyl glycol, is mentioned. In any case, the polyester referred to in the present invention refers to a polyester which is polyethylene terephthalate or the like in which 60 mol% or more, preferably 80 mol% or more is an ethylene terephthalate unit.

  In the polyester layer of the film of the present invention, it is preferable to blend particles for the main purpose of imparting slipperiness. 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 of the particles include magnesium, kaolin, aluminum oxide, and titanium oxide. 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. These series of particles may be used in combination of two or more as required.

  Moreover, the average particle diameter of the particle | grains to be used is 0.01-3 micrometers normally, Preferably it is the range of 0.01-1 micrometer. When the average particle diameter is less than 0.01 μm, the particles are likely to aggregate and dispersibility may be insufficient. On the other hand, when the average particle diameter exceeds 3 μm, the surface roughness of the film becomes too rough and Problems may occur when various surface functional layers are applied in the process.

  Further, the content of particles in the polyester layer is usually in the range of 0.001 to 5% by weight, preferably 0.005 to 3% by weight. When the particle content is less than 0.001% by weight, the slipperiness of the film may be insufficient. On the other hand, when the content exceeds 5% by weight, the transparency of the film is insufficient. There is.

  The method for adding particles to the polyester layer 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 constituting each layer, but it is preferably added after completion of esterification or transesterification.

  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, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film in the present invention as necessary.

  Although the thickness of the polyester film in this invention will not be specifically limited if it is a range which can be formed into a film as a film, Usually, it is 5-250 micrometers, Preferably it is the range of 10-200 micrometers.

  Next, although the manufacture example of the polyester film in this invention is demonstrated concretely, it is not limited to the following manufacture examples at all. That is, a method of using the polyester raw material described above and cooling and solidifying a molten sheet extruded from a die with a cooling roll to obtain an unstretched sheet is preferable. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method and / or a liquid application adhesion method is preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, the film is stretched in the direction perpendicular to the first stretching direction. In that case, the stretching temperature is usually 70 to 170 ° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. is there. Subsequently, heat treatment is performed at a temperature of 180 to 270 ° C. under tension or under relaxation within 30% to obtain a biaxially oriented film. In the above-described stretching, a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

  In the present invention, the simultaneous biaxial stretching method can be adopted for the production of the polyester film constituting the laminated polyester film. The simultaneous biaxial stretching method is a method in which the above-mentioned unstretched sheet is usually stretched and oriented in the machine direction and the width direction at a temperature controlled normally at 70 to 120 ° C., preferably 80 to 110 ° C. Is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area magnification. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a stretched oriented film. With respect to the simultaneous biaxial stretching apparatus that employs the above-described stretching method, conventionally known stretching methods such as a screw method, a pantograph method, and a linear drive method can be employed.

  Furthermore, what is called an in-line coating which processes the film surface during the extending | stretching process of the above-mentioned polyester film can be given. When a coating layer is provided on a polyester film by in-line coating, coating can be performed simultaneously with stretching, and the thickness of the coating layer can be changed by the stretching ratio, so that a film suitable as a polyester film can be produced. .

  Next, formation of the coating layer which comprises the laminated polyester film in this invention is demonstrated. As for the coating layer, it may be provided on the polyester film by the above-mentioned in-line coating, a so-called off-line coating applied outside the system on the film once manufactured may be employed, or both may be used in combination. In-line coating is preferably used because it can be manufactured at low cost.

  The in-line coating is not limited to the following, but for example, in the sequential biaxial stretching, the coating treatment can be performed particularly before the lateral stretching after the longitudinal stretching is finished. When a coating layer is provided on a polyester film by in-line coating, coating can be performed simultaneously with film formation, and the coating layer can be processed at a high temperature, and a film suitable as a polyester film can be produced.

  In the present invention, it is an essential requirement to have a coating layer containing a compound having a bisphenol A structure on at least one side of a polyester film stretched in at least a uniaxial direction.

  The compound having a bisphenol A structure used in the present invention is not particularly limited as long as the compound has a structure represented by the following formula (1) in the compound. Examples thereof include an epoxy compound having a bisphenol A structure, a polyester compound, an acrylic compound, and a polyurethane compound.

  In the compound having a bisphenol A structure used in the present invention, the proportion of the structure represented by the formula (1) in the compound is preferably in the range of 5 to 95% by weight, more preferably It is in the range of 10 to 90%. Further, the ratio of the structure represented by the formula (1) in the entire easy-adhesive coating layer is preferably in the range of 5 to 80% by weight, more preferably in the range of 10 to 70%, and still more preferably 10. It is in the range of ˜50%. When it is outside these ranges, the easy adhesion performance may be insufficient, or the visibility after the surface functional layer is laminated may be deteriorated. The ratio of the structure represented by the formula (1) can be determined by, for example, dissolving and extracting a resin or a coating layer with an appropriate solvent or warm water, separating by molecular weight by chromatography, analyzing the structure by NMR, and further thermally decomposing. It can obtain | require by analyzing by GC-MS (gas chromatography mass spectrometry).

As the epoxy compound having a bisphenol A structure, one obtained most commonly by reaction of bisphenol A and epichlorohydrin can be mentioned. Furthermore, such an epoxy compound and other components may be copolymerized. For example, the thing which introduce | transduced the alkylene chain and the alkylene oxide can be illustrated. In addition, the epoxy compound having a bisphenol A structure in the present invention usually has a molecular weight of about 300 to 10,000. Other compounds obtained by copolymerizing the compounds exemplified above are also included in the compounds having a bisphenol A structure in the present invention.

  As a polyester-type compound which has a bisphenol A structure, the polyester which uses the alkylene oxide adduct of bisphenol A etc. can be illustrated, for example. That is, the polyester compound as the coating layer component can be exemplified by a compound obtained by polycondensation of a polyvalent carboxylic acid and a polyvalent hydroxy compound. As a part or all of the polyvalent hydroxy compound, an alkylene of such bisphenol A can be used. This means that an oxide adduct is used.

  In addition, composite polymers having a polyester component such as a so-called acrylic graft polyester described in JP-A-1-165633 and polyester polyurethane obtained by chain-extending a polyester polyol with an isocyanate also have a bisphenol A structure in the compound. If introduced, it can be used as a polyester as a component constituting the coating layer used in the present invention.

  An acrylic compound having a bisphenol A structure is a polymer in which a bisphenol A structure is introduced into a polymer composed of a polymerizable monomer having a carbon-carbon double bond, as represented by an acrylic or methacrylic monomer. It is. These may be either a homopolymer or a copolymer. Moreover, the copolymer of these polymers and other polymers (for example, polyester, polyurethane, etc.) is also included. For example, a block copolymer or a graft copolymer. Alternatively, a polymer (possibly a mixture of polymers) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyester solution or a polyester dispersion is also included. Similarly, a polymer (in some cases, a mixture of polymers) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyurethane solution or polyurethane dispersion is also included. Similarly, a polymer obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in another polymer solution or dispersion (in some cases, a polymer mixture) is also included.

  In order to introduce a bisphenol A structure into a polymer composed of the above polymerizable monomer, for example, a monomer obtained by adding bisphenol A or an alkylene oxide adduct of bisphenol A to the carboxy group of the polymerizable monomer, There are methods such as polymerization.

  The polyurethane-based compound having a bisphenol A structure is a compound containing a structure represented by the formula (1) in a part of a polyurethane resin composed of a polyol and a polyisocyanate. As the production method, a known method can be applied. For example, a prepolymer having a terminal isocyanate is synthesized from a polyol and an excess of polyisocyanate, and then this prepolymer is reacted with a chain extender or a crosslinking agent. There are methods for increasing the molecular weight. By using a compound having a bisphenol A structure as the polyol or polyisocyanate, a polyurethane-based compound having a bisphenol A structure can be obtained.

  In the present invention, a compound other than the compound having the bisphenol A structure, for example, a resin such as a polyester resin, an acrylic resin, or a polyvinyl resin may be used in combination as long as the effect of the present invention is not affected. Moreover, combined use of crosslinking agents, such as a melamine compound and an oxazoline compound, can also be used together in the range which does not affect the effect of this invention. Further, a compound having a metal element such as a titanium chelate compound or a zirconium acylate compound can be used in combination.

  Further, for the purpose of improving the adhesion and slipperiness of the coating layer, inert particles may be contained, and specific examples include silica, alumina, kaolin, calcium carbonate, titanium oxide, organic particles, and the like.

  Furthermore, as long as it does not impair the gist of the present invention, an antifoaming agent, a coating property improver, a thickener, an organic lubricant, an antistatic agent, an antioxidant, an ultraviolet absorber, a foaming agent, a dye, etc. May be contained.

  It is preferable to produce a laminated polyester film by coating the above-mentioned series of compounds as a solution or dispersion on a polyester film with a coating solution adjusted to a solid content concentration of about 0.1 to 50% by weight. .

  Furthermore, in the case of in-line coating, the above-described series of compounds is used as an aqueous solution or water dispersion, and the coating solution adjusted with a solid content concentration of about 0.1 to 50% by weight as a guide is laminated on the polyester film. It is preferred to produce a polyester film. Moreover, in the range which does not impair the main point of this invention, a small amount of organic solvents may be contained in the coating liquid for the purpose of improving dispersibility in water, improving film-forming properties, and the like. Only one type of organic solvent may be used, or two or more types may be used as appropriate.

Although there is no restriction | limiting in the application quantity (after drying) of the coating layer provided on a polyester film regarding the lamination | stacking polyester film in this invention, Usually 0.005-1g / m < ² >, Preferably 0.005-0.5g / m ² range. When the coating amount is less than 0.005 g / m ² , the uniformity of the coating thickness may be insufficient. On the other hand, when the coating is applied in excess of 1 g / m ² , problems such as a decrease in slipperiness may occur.

  In the present invention, as a method for providing the coating layer, a conventionally known coating method such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating or the like can be used. Regarding the coating method, there is a description example in “Coating method” published by Yasuharu Harasaki in 1979.

  In the present invention, the drying and curing conditions for forming the coating layer on the polyester film are not particularly limited. For example, when the coating layer is provided by off-line coating, it is usually 3 to 40 at 80 to 200 ° C. The heat treatment may be performed for 2 seconds, preferably 100 to 180 ° C. for 3 to 40 seconds.

  On the other hand, when the coating layer is provided by in-line coating, heat treatment is usually performed at 70 to 280 ° C. for 3 to 200 seconds as a guide.

  Further, irrespective of off-line coating or in-line coating, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used in combination as required. The polyester film constituting the laminated polyester film in the present invention may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

  The absolute reflectance of the polyester film on which the coating layer is laminated is 4.0% or more, preferably 4.5% or more at an arbitrary wavelength of 350 to 800 nm, and the absolute reflectance of the polyester film on which the coating layer is not laminated. It is preferable that it is less than. When the absolute reflectance is less than 4.0%, the anti-reflection performance deteriorates when a surface functional layer such as a hard coat layer or an anti-reflection layer is formed on the coating layer of the film, resulting in strong interference unevenness. And visibility may be reduced.

  Further, the total light transmittance of the laminated polyester film in the present invention is 80% or more, and transparency is particularly required for optical applications such as used in the production of display members such as LCD, PDP, and organic EL. It is preferable because it can be used for applications, and more preferably 85% or more. When the total light transmittance is less than 80%, the transparency becomes insufficient. For example, when used in an inspection process involving optical evaluation, there may be a problem that foreign matters are easily overlooked.

  According to the laminated polyester film for optics of the present invention, it is possible to provide an optical film excellent in antireflection performance when various surface functional layers are laminated, and its industrial value is 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 measurement method and evaluation method used in the present invention are as follows.

(1) Measurement of intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed are precisely weighed, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) is added. It was dissolved and measured at 30 ° C.

(2) Measurement of average particle diameter (d ₅₀ : μm) Integration (weight basis) 50% in equivalent spherical distribution measured using centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type manufactured by Shimadzu Corporation) Was the average particle size.

(3) Measuring method of reflectance from one coating layer surface in polyester film A black tape (vinyl tape VT-50 manufactured by Nichiban Co., Ltd.) was previously pasted on the measurement back surface of the polyester film, and a spectrophotometer (Shimadzu Corporation) Using the UV-3100PC type), the absolute reflectance of the coating layer surface was measured at an incident angle of 5 °, a wavelength range of 350 to 800 nm, a sampling pitch of 1 nm, a slit width of 2 nm, and a low scanning speed, and the minimum value was evaluated. .

(4) Adhesion measurement method A 2: 1 mixture of KAYARAD (registered trademark) manufactured by Nippon Kayaku Co., Ltd. and Shikou (registered trademark) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. It was applied and dried at 80 ° C. for 1 minute to remove the solvent. Next, while running the film at a feeding speed of 10 m / min, ultraviolet rays were irradiated using a mercury lamp under the conditions of irradiation energy of 120 W / cm and irradiation distance of 10 cm to obtain a film having a surface functional layer. A cross cut (100 squares of 1 mm ² ) is applied to the film, and an 18 mm wide tape (Cello Tape (registered trademark) CT-18 manufactured by Nichiban Co., Ltd.) is applied to the film, and a peeling angle of 180 degrees is applied. After peeling off rapidly, the peeled surface was observed. If the peeled area was less than 20%, it was evaluated as ◯, if it was 20% or more but less than 50%, Δ, and if it was 50% or more, ×.

(5) Evaluation method of antireflection ability On the coating layer side of the laminated polyester film, a 2: 1 mixture of KAYARAD (registered trademark) manufactured by Nippon Kayaku Co., Ltd. and Shikou (registered trademark) manufactured by Nippon Synthetic Chemical Industry Was applied and dried at 80 ° C. for 1 minute to remove the solvent. Next, while running the film at a feed rate of 10 m / min, ultraviolet rays were irradiated using a mercury lamp under the conditions of irradiation energy of 120 W / cm and irradiation distance of 10 cm to obtain a film having a surface functional layer having a thickness of 10 μm. . The obtained film was visually observed under a three-wavelength light region type fluorescent lamp, and interference unevenness was observed.

The polyester used in the examples and comparative examples was prepared as follows.
<Manufacture of polyester>
100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, the temperature is raised by heating, methanol is distilled off, transesterification is performed, and 4 hours are required from the start of the reaction. The temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, 0.04 part of ethyl acid phosphate, 0.03 part of antimony trioxide and 0.01 part of silica particles having an average particle diameter of 1.5 μm were added, and then the temperature reached 280 ° C. and the pressure reached 15 mmHg in 100 minutes. After that, the pressure was gradually reduced after that to finally reach 0.3 mmHg. After 4 hours, the system was returned to normal pressure to obtain polyethylene terephthalate having an intrinsic viscosity of 0.61.

Examples of compounds constituting the coating layer are as follows.
(Example compounds)
Epoxy compound having bisphenol A structure: (A)
Epoxy compound having an average molecular weight of about 400 obtained by reacting bisphenol A and epichlorohydrin in the presence of sodium hydroxide Polyester resin: (B)
Water dispersion of polyester resin copolymerized with the following composition: Monomer 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%)
Hexamethoxymethylmelamine: (C)
Particle: (D) Silica sol having an average particle diameter of 65 nm

Example 1:
The produced polyethylene terephthalate was dried at 180 ° C. for 4 hours in an inert gas atmosphere, melted at 290 ° C. by a melt extruder, extruded from a die, and cooled by setting the surface temperature to 40 ° C. using an electrostatic application adhesion method. It cooled and solidified on the roll and the unstretched sheet was obtained. Next, the obtained unstretched sheet was first longitudinally stretched 3.6 times at 95 ° C., and the following coating agent was applied by a bar coating method. Stretching was performed. Then, it heat-set at 230 degreeC for 3 second, and obtained the 50-micrometer-thick polyester film in which the coating layer of the composition shown below whose coating amount (after drying) was 0.1 g / m < ² > was provided.

<< Coating layer composition >>
Epoxy compound having bisphenol A structure (A): 47% by weight
Polyester resin (B): 20% by weight
Hexamethoxymethylmelamine (C): 30% by weight
Silica sol having an average particle diameter of 65 nm (D): 3% by weight
The concentration of the coating solution was 10% by weight.

  When the reflectance of the finished laminated polyester film was measured in the wavelength range of 350 to 800 nm, the minimum value was 5.1%. When the interference unevenness after laminating the surface functional layer was observed, the visibility was good. The characteristics of this film are shown in Table 1 below.

Example 2 to Example 3 :
In Example 1, except having changed a coating agent composition into the coating agent composition shown in Table 1, it manufactured like Example 1 and obtained the laminated polyester film. As shown in Table 1, the finished polyester film had a high reflectance, and when the interference unevenness after laminating the surface functional layer was observed, the visibility was good.

Comparative Examples 1 and 2:
In Example 1, except having changed a coating agent composition into the coating agent composition shown in Table 1, it manufactured like Example 1 and obtained the laminated polyester film. When the completed laminated polyester film was evaluated, as shown in Table 1, deterioration of visibility due to interference unevenness and deterioration of adhesion with the surface functional layer were observed.

Comparative Example 3:
In Example 1, it manufactured similarly to Example 1 except having not provided the application layer, and obtained the polyester film. When the completed laminated polyester film was evaluated, as shown in Table 1, deterioration of visibility due to uneven interference and deterioration of adhesion were observed.

  The film of the present invention can be suitably used for, for example, LCDs, PDPs, organic ELs, and other optical applications for producing display members, and applications that place importance on visibility.

Claims (1)

A coating amount (after drying) obtained by applying and drying a coating solution containing a polyester resin, an epoxy compound having a bisphenol A structure, and a melamine compound on at least one surface of a polyester film stretched at least in a uniaxial direction. Has a coating layer in the range of 0.005 to 0.5 g / m ² , and the total amount of the epoxy compound having a bisphenol A structure and the melamine compound in the coating layer is 56 to 385 with respect to the polyester resin 100. An optically laminated polyester film characterized by being in a range.