JP5140212B2 - Optical laminated polyester film - Google Patents

Description

  The present invention relates to a laminated polyester film, such as a liquid crystal display (hereinafter abbreviated as LCD), a plasma display panel (hereinafter abbreviated as PDP), organic electroluminescence (hereinafter abbreviated as organic EL), and the like. The present invention provides an optical 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, in applications such as LCD and PDP display members, there has been a demand for larger screens, higher image quality, and higher quality, and accordingly, there is a demand for suppression of 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.

  In addition, the demand for PDPs as display panels for various electronic devices including large-sized wall-mounted televisions is increasing, and the number is expected to increase in the future. In a plasma display, a gas mixture of xenon and neon is excited by discharge to emit vacuum ultraviolet light, and red, blue, and green phosphors are emitted by the vacuum ultraviolet light excitation. After neon atoms are excited, When returning to the ground state, it is known to emit so-called neon orange light centered around 600 nm (Non-Patent Document 1). For this reason, in a plasma display, since red is mixed with orange and there is a defect that a bright red cannot be obtained, a color filter for color tone correction using a dye having maximum absorption at a light wavelength of 560 to 600 nm. Is installed on the front of the plasma display to absorb the neon orange light well so that the red of the plasma display looks bright red.

  As a method for protecting the pigment used in the color filter from UV degradation, studies have been made to incorporate an ultraviolet absorber into the polyester film itself used as a protective film for the plasma display front plate so as to have an ultraviolet blocking function. A polyester film containing a general ultraviolet absorber has a problem that hinders the correction of the color tone of the color filter due to its strong yellowishness, but the polyester film contains a benzoxazinone-based ultraviolet absorber. There is also an example solved by using.

  However, hard coats used for various optical applications in recent years may have a high refractive index in order to achieve high functionality, and coating with conventional resins such as polyester resins, acrylic resins, urethane resins, etc. Since the refractive index of the layer is fixed at around 1.50, when designing an antireflection film, the performance of antireflection is limited, and the occurrence of uneven interference due to reflection of external light may not be sufficiently suppressed. . 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 2004-10875 A JP-A-10-119215 JP 2000-246855 A Japanese Patent No. 3632044 JP 2004-54161 A JP 2005-189740 A JP 2005-189741 A The Journal of the Institute of Image Information and Television Engineers Vol. 51 NO. 4P. 459-463 (1997)

  The present invention has been made in view of the above circumstances, and the problem to be solved is an LCD, PDP, low UV transmittance, low yellowness, excellent color tone, and reduced interference unevenness due to external light reflection. Another object is to provide a laminated polyester film suitable for various optical applications, such as for the production of various display component materials, such as for the production of display members such as organic EL.

  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 a coating solution containing an alkenyl-substituted nadiimide compound and a melamine compound on at least one surface of a polyester film containing at least uniaxial direction and containing 0.20 to 10.0% by weight of an ultraviolet absorber. The laminated polyester film for optics has a coating layer formed from the above, and has a light transmittance of 380 nm or less of 5.0% or less.

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

  The laminated polyester film for optics of the present invention is one in which an ultraviolet absorber is contained in a polyester film. The ultraviolet absorber is not particularly limited as long as it is a compound having ultraviolet absorbing ability and can withstand the heat applied in the production process of the polyester film.

  As the ultraviolet absorber, there are an organic ultraviolet absorber and an inorganic ultraviolet absorber. From the viewpoint of transparency, an organic ultraviolet absorber is preferred. Although it does not specifically limit as an organic type ultraviolet absorber, For example, a cyclic imino ester type, a benzotriazole type, a benzophenone type etc. are mentioned. From the viewpoint of durability, a cyclic imino ester type and a benzotriazole type are more preferable. It is also possible to use two or more ultraviolet absorbers in combination.

  Examples of the benzotriazole-based ultraviolet absorbers include, but are not limited to, 2- [2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl] -2H-benzotriazole, 2- [2 '-Hydroxy-5'-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2- [2'- Hydroxy-5 '-(methacryloyloxyhexyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-3'-tert-butyl-5'-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2 -[2'-hydroxy-5'-tert-butyl-3 '-(methacryl Yloxyethyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl) phenyl] -5-chloro-2H-benzotriazole, 2- [2′-hydroxy-5 ′ -(Methacryloyloxyethyl) phenyl] -5-methoxy-2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-cyano-2H-benzotriazole, 2- [2 '-Hydroxy-5'-(methacryloyloxyethyl) phenyl] -5-tert-butyl-2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-nitro-2H -Benzotriazole and the like.

  Examples of the cyclic imino ester-based ultraviolet absorber include, but are not limited to, 2-methyl-3,1-benzoxazin-4-one, 2-butyl-3,1-benzoxazine-4, for example. -One, 2-phenyl-3,1-benzoxazin-4-one, 2- (1- or 2-naphthyl) -3,1-benzoxazin-4-one, 2- (4-biphenyl) -3, 1-benzoxazin-4-one, 2-p-nitrophenyl-3,1-benzoxazin-4-one, 2-m-nitrophenyl-3,1-benzoxazin-4-one, 2-p-benzoyl Phenyl-3,1-benzoxazin-4-one, 2-p-methoxyphenyl-3,1-benzoxazin-4-one, 2-o-methoxyphenyl-3,1-benzoxazin-4-one, -Cyclohexyl-3,1-benzoxazin-4-one, 2-p- (or m-) phthalimidophenyl-3,1-benzoxazin-4-one, N-phenyl-4- (3,1-benzoxazine -4-On-2-yl) phthalimide, N-benzoyl-4- (3,1-benzoxazin-4-one-2-yl) aniline, N-benzoyl-N-methyl-4- (3,1- Benzoxazin-4-one-2-yl) aniline, 2- (p- (N-methylcarbonyl) phenyl) -3,1-benzoxazin-4-one, 2,2′-bis (3,1-benzo Oxazin-4-one), 2,2′-ethylenebis (3,1-benzoxazin-4-one), 2,2′-tetramethylenebis (3,1-benzoxazin-4-one), 2, 2'-Decame Renbis (3,1-benzoxazin-4-one, 2,2'-p-phenylenebis (3,1-benzoxazin-4-one), 2,2'-m-phenylenebis (3,1-benzo Oxazin-4-one), 2,2 ′-(4,4′-diphenylene) bis (3,1-benzoxazin-4-one), 2,2 ′-(2,6- or 1,5-naphthylene) ) Bis (3,1-benzoxazin-4-one), 2,2 ′-(2-methyl-p-phenylene) bis (3,1-benzoxazin-4-one), 2,2 ′-(2 -Nitro-p-phenylene) bis (3,1-benzoxazin-4-one), 2,2 '-(2-chloro-p-phenylene) bis (3,1-benzoxazin-4-one), 2 , 2 '-(1,4-cyclohexylene) bis (3,1-benzoo Sadin-4-one), 1,3,5-tri (3,1-benzoxazin-4-one-2-yl) benzene, 1,3,5-tri (3,1-benzoxazin-4-one) -2-yl) naphthalene, 2,4,6-tri (3,1-benzoxazin-4-one-2-yl) naphthalene, 2,8-dimethyl-4H, 6H-benzo (1,2-d; 5,4-d ′) bis (1,3) -oxazine-4,6-dione, 2,7-dimethyl-4H, 9H-benzo (1,2-d; 4,5-d ′) bis (1 , 3) -Oxazine-4,9-dione, 2,8-diphenyl-4H, 8H-benzo (1,2-d; 5,4-d ′) bis (1,3) -oxazine-4,6- Dione, 2,7-diphenyl-4H, 9H-benzo (1,2-d; 4,5-d ′) bis (1,3) -oxazine 4,6-dione, 6,6′-bis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6′-bis (2-ethyl-4H, 3,1-benzoxazine) -4-one), 6,6'-bis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6'-methylenebis (2-methyl-4H, 3,1-benzoxazine) -4-one), 6,6'-methylenebis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6'-ethylenebis (2-methyl-4H, 3,1-benzo) Oxazin-4-one), 6,6′-ethylenebis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6′-butylenebis (2-methyl-4H, 3,1- Benzoxazin-4-one), 6,6′-butylenebis (2- Phenyl-4H, 3,1-benzoxazin-4-one), 6,6′-oxybis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6′-oxybis (2- Phenyl-4H, 3,1-benzoxazin-4-one), 6,6′-sulfonylbis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6′-sulfonylbis ( 2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6′-carbonylbis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6′-carbonyl Bis (2-phenyl-4H, 3,1-benzoxazin-4-one), 7,7′-methylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 7,7′- Methylenebis (2-phenyl-4H 3,1-benzoxazin-4-one), 7,7′-bis (2-methyl-4H, 3,1-benzoxazin-4-one), 7,7′-ethylenebis (2-methyl-4H) , 3,1-benzoxazin-4-one), 7,7′-oxybis (2-methyl-4H, 3,1-benzoxazin-4-one), 7,7′-sulfonylbis (2-methyl-) 4H, 3,1-benzoxazin-4-one), 7,7′-carbonylbis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,7′-bis (2-methyl) -4H, 3,1-benzoxazin-4-one), 6,7'-bis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,7'-methylenebis (2-methyl- 4H, 3,1-benzoxazin-4-one), 6,7 ′ Methylene bis (2-phenyl-4H, 3,1-benzoxazin-4-one), and the like.

Among the above compounds, when the color tone is taken into consideration, a benzoxazinone-based compound that is difficult to be yellowed is preferably used, and examples thereof include those represented by the following formula (1). .

  In the above formula, R represents a divalent aromatic hydrocarbon group, and X1 and X2 are each independently selected from hydrogen or the following functional group group, but are not necessarily limited thereto.

Functional group: alkyl group, aryl group, heteroaryl group, halogen, alkoxyl group, aryloxy group, hydroxyl group, carboxyl group, ester group, nitro group Among the compounds represented by the above structural formula, in the present invention, 2,2 ′-(1,4-phenylene) bis [4H-3,1-benzoxazin-4-one] is particularly preferred.

  The optical laminated polyester film of the present invention contains an ultraviolet absorber in an amount of usually 0.20 to 10.0% by weight, preferably 0.3 to 1.8% by weight. When the ultraviolet absorber is less than 0.20% by weight, the dye in the filter may be deteriorated by the ultraviolet rays transmitted through the polyester film. When the ultraviolet absorber is contained in an amount exceeding 10.0% by weight May bleed out the ultraviolet absorber on the surface, leading to deterioration of surface functionality such as adhesion deterioration.

  The optical laminated polyester film of the present invention has a light transmittance at a wavelength of 380 nm of 5.0% or less, preferably 2.0% or less, more preferably 1.0% or less. When the light transmittance at a wavelength of 380 nm is larger than 5.0%, it cannot be said that it is sufficient to prevent the dye in the filter from being deteriorated by the ultraviolet rays transmitted through the polyester film.

  The specular reflectance on the side of the coating layer provided on at least one side of the optically laminated polyester film of the present invention is usually 5.0% or more, preferably 5.5% or more at an arbitrary wavelength of 400 to 800 nm. It is preferable that it is less than the specular reflectance of the polyester film on which the coating layer is not laminated. When the specular reflectance is less than 5.0%, 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.

The laminated polyester film for optics of the present invention has a color tone b ^* value measured by a single transmission method of usually 1.5 or less, preferably 1.0 or less, and more preferably 0.8 or less. When b ^* is 1.5 or more, the yellowish color is so strong that it may become inappropriate as a laminated polyester film for optics.

  Moreover, it is preferable that the total light transmittance of the laminated polyester film for optics in the present invention is 80% or more, since it becomes possible to cope with applications that particularly require transparency, 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.

  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 0.01-2 micrometers. 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.

  In the case of a film having a laminated structure, it is preferably at least a three-layer structure, and the ultraviolet absorber is preferably blended in the intermediate layer. By blending an ultraviolet absorber in the intermediate layer, the compound can be prevented from bleeding out to the film surface, and as a result, properties such as film adhesion can be maintained.

  In addition, due to thermal history during film processing, oligomers contained in the film are deposited on the film surface, which may cause deterioration of visibility of the film due to contamination of the production line or deterioration of film haze, etc. It is preferable to use low oligomerized polyester for the outermost layer of the structural film. As a method for reducing the amount of oligomer in the polyester, conventionally known solid phase polymerization can be used.

  The thickness of the polyester film in the present invention is not particularly limited as long as it can be formed as a film, but is usually 50 to 300 μm, preferably 75 to 250 μm.

  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 necessary 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 are 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 an imide compound having an aromatic compound in the molecule on at least one surface of a polyester film stretched in at least a uniaxial direction.

  The imide compound having an aromatic compound in the molecule is not particularly limited as long as the imide compound has an aromatic compound such as a benzene ring or a naphthalene ring in the molecule. If the aromatic compound is not present in the molecule, the refractory index of the coating layer may not be sufficiently improved only by the imide structure, and interference unevenness when the surface functional layer is laminated may not be sufficiently improved.

  As the imide compound, an imide compound represented by the following general formula (2) is more preferably used in consideration of appropriateness as a coating agent and difficulty in production.

In the above formula, at least one of R ¹ , R ² and R ³ is a group having an aromatic compound, and n represents an integer of 1 or 2.

R ¹ and R ² may be the same or different and each represents a hydrogen atom, an alkyl group, an alkenyl group, or a phenyl group. R ³ is an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or a monovalent aromatic having 6 to 12 carbon atoms when n is 1. A group or a benzyl group, or a group-[(C _q H _2q O) _t (C _r H _2r O) _u C _v H _{2v + 1} ] (where q, r and v are each an integer of 2 to 6) T represents an integer of 0 or 1, u represents an integer of 1 to 30) or a group —C ₆ H ₄ —T—C ₆ H ₅ {where T is —CH ₂ —, —C ( Represents CH ₃ ) ₂ —, —CO—, —O—, —S—, —SO ₂ —.

R ³ is an alkylene group having 2 to 20 carbon atoms, a cycloalkylene group having 5 to 8 carbon atoms, a group — [(C _x H _2x O) _y (C _z H _2z O) _w C when n is 2. _b H _2b ]-(wherein x, z and b each represent an integer of 2 to 6, y represents an integer of 0 or 1, and w represents an integer of 1 to 30), 6 to 6 carbon atoms 12 divalent aromatic groups, group —R—C ₆ H ₄ — (R ′) _m — (where m represents an integer of 0 or 1, and R and R ′ may be the same or different. , Represents a C 1-4 alkylene group or a C 5-8 cycloalkylene group) or a group —C ₆ H ₄ —A—C ₆ H ₄ — {where A is —CH ₂ —, —C ( _{CH 3) 2 -, - CO} -, - O -, - OC 6 H 4 C (CH 3) 2 C 6 H 4 O -, - S -, - SO 2 - shows a. }.

In the R ³ group, 1 to 3 hydrogen atoms may be substituted with a hydroxyl group, a carboxyl group, an amino group, a mercapto group, a carbamoyl group, or an isocyano group.

In the general formula (2), examples of the asymmetric alkylene / phenylene group contained in the group —R—C ₆ H ₄ — (R ′) _m — represented by R ³ in the case of n = 2 include, for example, the formula ( What is represented by 3) is mentioned.

In order to make the formed coating layer tough, it is preferable that at least one of R ^{1 and} R ² has an alkenyl group, and an alkenyl-substituted nadiimide represented by the following formula (4) is preferably used. .

In the above formula, R ⁴ represents a hydrogen atom or a methyl group.

  The imide compound having an aromatic compound in the molecule used in the present invention is not limited to these. Moreover, the imide compound which has these aromatic compounds in a molecule | numerator may be used independently, may be used in mixture of multiple types, and also may be used as an oligomer.

  In addition, in order to more efficiently cure an imide compound having an aromatic compound in the molecule, for example, an organic peroxide, an inorganic peroxide, an onium salt, a cation catalyst, and an organic group-containing metal compound are used in combination as a curing catalyst. It is also possible to do.

  In the laminated polyester film of the present invention, a binder polymer is used to improve antireflection performance and transparency when various surface functional layers are laminated on the coated surface, and to improve adhesion to various surface functional layers. It is also possible to use together.

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

  Specific examples of the binder polymer include polyester resin, acrylic resin, urethane resin, polyvinyl (polyvinyl alcohol, polyvinyl chloride, vinyl chloride vinyl acetate copolymer, etc.), polyalkylene glycol, polyalkylene imine, methyl cellulose, hydroxy cellulose, and starch. And the like.

  By including a binder polymer having an aromatic ring skeleton in the above-described binder polymer in the coating layer, the antireflection ability when various surface functional layers are laminated on the coating surface is further improved. preferable.

  Furthermore, a crosslinking agent may be used in combination in the coating layer as long as the gist of the present invention is not impaired, and specific examples include methylolated or alkylolated urea, melamine, guanamine, acrylamide, and polyamide systems. Examples thereof include compounds, oxazoline compounds, epoxy compounds, aziridine compounds, block polyisocyanates, and silane coupling agents. These crosslinking components may be previously bonded to the binder polymer.

  In addition, 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 improving agent, a thickener, an organic lubricant, an antistatic agent, an antioxidant, a foaming agent, a dye, and the like are contained as necessary. Also good.

  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. 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.

  According to the laminated polyester film for optics of the present invention, it is possible to provide an optical film having good ultraviolet absorption and excellent antireflection performance when laminating various surface functional layers, 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 (d50) The particle size was measured by a sedimentation method based on Stokes' resistance law using a centrifugal sedimentation type particle size distribution analyzer SA-CP3 manufactured by Shimadzu Corporation.

(3) Measurement of light transmittance Using a spectrophotometer (UV-3100PC type, manufactured by Shimadzu Corporation), the light transmittance is continuously measured in a scan speed of 2 nm, a sampling pitch of 2 nm, and a wavelength of 300 to 700 nm. The light transmittance at a wavelength of 380 nm was detected.

(4) Measurement of color tone b ^* Value with spectrophotometer SE-2000 (manufactured by Nippon Denshoku Co., Ltd.), C light source, 2 degree visual field, transmission method, sample color tone (L ^* , A ^* , b ^* ) were measured, and the degree of yellowness was evaluated by the b ^* value.

(5) Method for measuring reflectance from one coating layer surface in polyester film A black tape (vinyl tape VT-50 manufactured by Nichiban Co., Ltd.) was previously applied to the measurement back surface of the polyester film, and a spectrophotometer (Shimadzu Corporation) Measure the specular reflectance of the coating layer surface at an incident angle of 8 °, a wavelength range of 400 to 800 nm, a sampling pitch of 1 nm, a slit width of 20 nm, and a medium scanning speed using an UV-3100PC model manufactured by the company, and evaluate the minimum value. did.

(6) Color tone visual evaluation evaluation method O300E100 (Diafoil (registered trademark) manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.), which is a general type polyester film not containing an ultraviolet absorber, is cut into an A4 cut plate as a standard sample. The color tone of the film sample containing a UV absorber placed on a white mount and similarly placed on the white mount was evaluated according to the following criteria.
○: The color tone is the same as the standard sample (good color tone)
Δ: The film is slightly colored (slightly good color tone)
×: Coloring of the film is remarkably lacking in practicality (color tone defect)

(7) Thickness measurement of laminated polyester layer 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 a transmission electron micrograph. Two of the cross-sections are observed in parallel with the film surface, and the interface is observed by light and dark. The distance between the two interfaces and the film surface was measured from 10 photographs, and the average value was defined as the laminated thickness.

(8) 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. is applied to the coated layer side of the laminated polyester film. 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, ×.

(9) Evaluation method of antireflection ability On the coating layer side of the laminated polyester film, a 2: 1 mixed solution of KAYARAD (registered trademark) manufactured by Nippon Kayaku Co., Ltd. and Shikko (registered trademark) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. 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.
<Method for producing polyester (A)>
Using 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol as starting materials, 0.09 parts by weight of magnesium acetate tetrahydrate as a catalyst is placed in the reactor, the reaction start temperature is set to 150 ° C., and the methanol is distilled off gradually. The reaction temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. After adding 0.04 part of ethyl acid phosphate to this reaction mixture, 0.04 part of antimony trioxide was added, and a polycondensation reaction was carried out 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 an intrinsic viscosity 0.75 polyester (B).

<Method for producing polyester (C)>
In the method for producing polyester (A), after adding 0.04 part of ethyl acid phosphate, 0.2 part of silica particles dispersed in ethylene glycol having an average particle diameter of 1.6 μm and 0.04 part of antimony trioxide are added. In addition, polyester (C) was obtained using the same method as the production method of polyester (A) except that the polycondensation reaction was stopped at the time corresponding to the intrinsic viscosity of 0.65. The obtained polyester (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] (CYTECOR manufactured by CYTEC Co., Ltd.) as an ultraviolet absorber. UV-3638 (Molecular weight 369 benzoxazinone) was supplied at a concentration of 10% by weight, melted and 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.

ポリエステル樹脂：（Ｂ）
下記組成で共重合したポリエステル樹脂の水分散体
モノマー組成：（酸成分）テレフタル酸／イソフタル酸／５−ソジウムスルホイソフタル酸／／（ジオール成分）エチレングリコール／１，４−ブタンジオール／ジエチレングリコール＝５６／４０／４／／７０／２０／１０（ｍｏｌ％）
ヘキサメトキシメチルメラミン：（Ｃ）
粒子：（Ｄ） 平均粒径６５ｎｍのシリカゾル Examples of compounds constituting the coating layer are as follows.
(Example compounds)
Alkenyl-substituted nadiimide (A): A compound represented by the following formula (5) was used.

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:
A mixed raw material in which the polyesters (B) and (C) were mixed at a ratio of 90% and 10%, respectively, was used as a raw material for the A layer, and the polyesters (A) and (D) were mixed at a ratio of 90% and 10%, respectively. Casting with mixed raw material as raw material of B layer, each supplied to two extruders, melted at 285 ° C each, then cooled to 40 ° C with A layer as outermost layer (surface layer) and B layer as intermediate layer A non-oriented sheet was obtained by co-extrusion on a drum in a layer configuration of two types and three layers (ABA) and cooling and solidifying.

Next, the film was stretched 3.4 times in the longitudinal direction at a film temperature of 85 ° C. using the difference in peripheral speed of the roll, and then the coating liquid 1 shown in Table 1 below was applied to both sides of the longitudinally stretched film, and led to a tenter. The film was stretched 3.6 times at 120 ° C in the transverse direction, heat treated at 225 ° C, relaxed by 2% in the transverse direction, and the film was rolled up at a production rate of 30 m / min. ) Obtained a laminated polyester film having a coating layer of 0.1 g / m ² and a thickness of 100 μm and an intrinsic viscosity of 0.61. The layer structure is shown in Table 2 below.

  When the specular reflectivity of the finished laminated polyester film was measured in the wavelength range of 400 to 800 nm, the minimum value was 6.5%. When the interference unevenness after laminating the surface functional layer was observed, the visibility was good. The properties of this film are shown in Table 3 below.

Example 2 to Example 4 :
In Example 1, except having changed the polyester layer and the coating liquid into the structure shown in Table 2, it manufactured like Example 1 and obtained the laminated polyester film. As shown in Table 3, 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 3, 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 finished laminated polyester film was evaluated, as shown in Table 3, interference unevenness occurred and visibility was deteriorated.

Comparative Example 4:
In Example 1, except having changed a polyester layer into the structure shown in Table 2, it manufactured like Example 1 and obtained the laminated polyester film. The completed polyester film had a high transmittance of 380 nm as shown in Table 3.

  The film of the present invention has an ultraviolet absorption function, and has good visibility after the surface functional layer is formed. For example, it can be suitably used for optical applications such as LCD, PDP, and organic EL display member production. Can do.

Claims (1)

At least one surface of a polyester film containing 0.20 to 10.0% by weight of an ultraviolet absorber stretched in at least a uniaxial direction has a coating layer formed from a coating solution containing an alkenyl-substituted nadiimide compound and a melamine compound. And an optical laminated polyester film having a light transmittance of 380 nm or less of 5.0% or less.