JP2008238586A - Biaxially stretched laminated polyester film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biaxially stretched laminated polyester film, excellent in the capability of blocking the UV of up to 410 nm, free from yellowish color, excellent in transparency, free from bad effects accompanying the bleed-out of a UV absorber and the like, and capable of being easily provided with an oxygen barrier layer. <P>SOLUTION: The biaxially stretched laminated polyester film is a laminated polyester film having at least three layers and contains, in the inner layer of the laminated structure, a UV absorber and an optical brightening agent in an amount of 0.1-9 mass% as a total. In the film the light transmittance of the wavelength 410 nm is ≤30% and the one of the wavelength 430 nm is ≥70%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a biaxially stretched laminated polyester film, and more particularly to a biaxially stretched laminated polyester film that is excellent in ultraviolet blocking ability up to 410 nm, has no yellowness, and is excellent in transparency.

  Polyester films have excellent mechanical properties, heat resistance, and dimensional stability at high temperatures, and are therefore widely used in food, pharmaceutical and cosmetic packaging applications as a bag by being laminated with a sealant agent. However, if oxygen is present inside the bag during storage, the contents are oxidized by the ultraviolet rays, causing a problem of discoloration or alteration. This problem is particularly serious when used for packaging foods and pharmaceuticals that contain fats and oils and coloring ingredients, and packaging that completely removes oxygen using UV- and oxygen-blocking packaging bags is used. It has been broken.

  Aluminum foil and aluminum-deposited polyester film are often used as such packaging bags, but there is a problem that the contents cannot be seen and the design of the product is impaired. In order to solve this problem, a transparent gas barrier coating technology has been developed in recent years, and a transparent gas barrier polyester film can be used. Further, as a method for blocking ultraviolet rays, a method of coating an ultraviolet absorber and a method of blending an ultraviolet absorber with polyester have been proposed (see, for example, Patent Document 1 and Patent Document 2).

  However, the method of coating with an ultraviolet absorber or the method of blending an ultraviolet absorber with polyester has insufficient performance as a packaging material. In addition, if a large amount of UV absorber is blended to improve UV blocking properties, the UV absorber will sublimate and decompose during film formation, causing problems in productivity and UV absorption on the film surface after film formation. The agent bleeds out and a gas barrier layer with good performance cannot be provided.

  In addition, most polyester films having ultraviolet absorbing ability have a long wavelength side absorption edge suppressed to shorter than 380 nm in order to suppress yellowishness (for example, see Patent Document 3). The fact that the absorption edge is a short wave means that the ultraviolet blocking effect is low. Therefore, it is desired to cut light up to 410 nm, particularly in order to block UVA, which is ultraviolet light in the wavelength range of 320 to 400 nm.

  However, when light up to 410 nm is cut, the yellow color of the film usually becomes strong. This yellowness can be apparently improved by adding a dye / pigment for adjusting the color tone, but has a disadvantage in that the transmittance in the visible region is sacrificed. A white laminated polyester film excellent in weather resistance and whiteness in which a fluorescent whitening agent is blended together with an ultraviolet absorber to suppress yellowing due to ultraviolet irradiation has been proposed (for example, see Patent Documents 4 and 5). Similar disadvantages are not resolved.

As described above, it has been difficult to obtain a film having no yellowishness, transparent, and UV-blocking and gas-blocking up to 410 nm.
JP-A-4-163145 Japanese Patent Laid-Open No. 1-264843 JP 2004-202899 A Japanese Patent Laid-Open No. 11-291432 JP 11-268214 A

  The present invention has been made in view of the above circumstances, and the solution is to have excellent ultraviolet blocking ability up to 410 nm, no yellowish color, excellent transparency, and no harmful effects associated with bleeding out of ultraviolet absorbers. More preferably, it is to provide a biaxially stretched laminated polyester film having excellent oxygen barrier properties.

  In general, the optical brightener comprises a compound having the property of absorbing light having a wavelength of about 320 to about 410 nm and emitting light having a wavelength of about 410 to about 500 nm. For example, in fabrics dyed with these fluorescent brighteners, in addition to the original yellow reflected light, blue light having a wavelength of about 410 to about 500 nm, which is newly emitted by the fluorescent whitener, is added. Although it is known that whitening is achieved and the visible light energy increases as a result of the fluorescence effect, the resulting whitening is a result. But I found that the same effect occurs. That is, in a molded product in which an ultraviolet absorber is added to a thermoplastic resin, if the amount of the ultraviolet absorber is adjusted so as to cut the ultraviolet rays of 410 nm or less, the reflected light feels yellow, but an appropriate amount of fluorescent whitening agent is added. It was found that the reflected light turned white. As a result of further intensive studies, it has been found that the above problem can be easily solved by applying this means to a film having a specific structure, and the present invention has been completed. Specific means for achieving the above object are as follows.

  <1> A laminated polyester film having at least three layers, wherein the inner layer of the laminated structure contains 0.1 to 9% by mass of an ultraviolet absorber and a fluorescent brightening agent in a total amount, and a light transmittance at a wavelength of 410 nm is 30. % Biaxially stretched laminated polyester film having a light transmittance at a wavelength of 430 nm of 70% or more.

  According to the biaxially stretched laminated film described in the above <1>, it is excellent in ultraviolet blocking ability up to 410 nm, has no yellowish color, can ensure transparency, and includes an ultraviolet absorber and a fluorescent whitening agent. Since the inner layer containing is sandwiched between the two outer layers, bleeding out of the ultraviolet absorber and / or fluorescent brightening agent can be suppressed.

  <2> The biaxially stretched laminated polyester film according to <1>, wherein the ultraviolet absorber is at least one selected from benzotriazole-based and cyclic iminoester-based ultraviolet absorbers.

  According to the biaxially stretched laminated polyester film described in <2>, the durability can be further ensured.

  <3> The biaxially stretched laminated polyester film according to claim 1 or 2, wherein the optical brightener comprises a compound represented by the following general formula (1).

In general formula (1), R ¹ and R ⁴ each independently represent a hydrogen atom, an alkyl group or an alkoxy group, and R ² and R ³ each independently represent an alkyl group. [A] represents a substituted aryl group or a substituted ethenyl group.

  According to the biaxially stretched laminated polyester film described in the above <3>, it is excellent in ultraviolet blocking ability up to 410 nm, has no yellowish color, and can secure more transparency and durability.

<4> The biaxially stretched laminate according to any one of <1> to <3>, further including a layer imparting oxygen barrier properties and having an oxygen permeability of 20 cc / m ² · day · atm or less. It is a polyester film.

  The biaxially stretched laminated polyester film according to the above <4> has excellent oxygen barrier properties and can prevent discoloration and alteration of the film even if it cannot completely block ultraviolet rays.

  According to the present invention, it is possible to provide a biaxially stretched laminated polyester film having excellent ultraviolet blocking ability up to 410 nm, no yellowish color, excellent transparency and excellent oxygen blocking property, and the industrial value of the present invention is high.

<Biaxially stretched laminated polyester film>
The present invention will be described in detail below. The biaxially stretched laminated polyester film of the present invention may be hereinafter referred to as “polyester film” or simply “film”.
The present invention is a laminated polyester film having at least three layers, and an ultraviolet absorber and a fluorescent whitening agent are contained in the inner layer of the laminated structure. In the present invention, the “inner layer” means a layer that is located on the inner side of the laminated body and has other films laminated on at least both surfaces, and itself is not exposed to the outside. In the case of a laminated film having a three-layer structure having 1 to 3 layers in this order, the second layer and in the case of a laminated film having a four-layer structure having 1 to 4 layers in this order, the second layer and the third layer. It means at least one layer.
In the outer layer, particularly the outermost layer of the laminated polyester film of the present invention, a layer containing particles of calcium carbonate or the like can be positioned for the purpose of improving the running property of the film.
Further, in the laminated polyester film of the present invention, for the purpose of protecting the laminated polyester film, a high-strength coat layer (for example, a diamond-like carbon layer, etc.) may be additionally provided as the outermost layer. it can.

  The laminated polyester film of the present invention is required to be a laminate of at least 3 layers. From the viewpoint of improving film running performance, achieving both ultraviolet blocking ability and oxygen shielding ability, and further, from the viewpoint of adhesion between each layer, 3 to 6 It is preferable that it is a layer, and it is more preferable that it is 3-5 layers. If the laminated structure of the polyester is less than three layers, at least one of the ultraviolet absorber and the fluorescent brightener from the layer containing the ultraviolet absorber and the fluorescent brightener cannot be prevented from bleeding out on the film surface. .

In addition, the film of the present invention needs to have a light transmittance at a wavelength of 410 nm of 30% or less and a light transmittance at a wavelength of 430 nm of 70% or more. If the light transmittance of the film is not 30% or less at 410 nm, discoloration or alteration of the package contents cannot be effectively prevented when this film is used as a packaging material. If the light transmittance at a wavelength of 430 nm is not set to 70% or more, the film has a yellowish color and excellent transparency cannot be ensured.
The light transmittance is preferably 20% or less at 410 nm and 75% or more at 430 nm. Moreover, discoloration or alteration of the contents can be prevented by setting the light transmittance at 380 nm to 30% or less, preferably 20% or less.
The light transmittance in the present invention is a value at 380 nm, 410 nm, and 430 nm when measured continuously with a spectrophotometer UV3100 (manufactured by Shimadzu Corporation) at a low scanning speed, a sampling pitch of 2 nm, and a wavelength of 300 to 700 nm. It is.

Each of the plurality of layers constituting the polyester film contains a polyester resin, which will be described later, as a main component, but in addition to polyester, achieves the ultraviolet blocking property and the visible light transmittance, and improves the transparency of the film. Means for obtaining include UV absorbers and fluorescent brighteners. This ultraviolet absorber and fluorescent brightening agent are contained in an inner layer having a layer structure of three or more layers.
Hereinafter, the polyester contained in the polyester film of the present invention and other compounding components will be described in detail.
-Polyester-
Examples of the polyester used in the biaxially stretched laminated polyester film of the present invention include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, 4,4′-diphenyldicarboxylic acid, 1,4-cyclohexyldicarboxylic acid. A dicarboxylic acid such as an acid, or an ester thereof (hereinafter appropriately referred to as an “acid component”), ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4 -Polyester produced by melt polycondensation with a glycol such as cyclohexanedimethanol (hereinafter appropriately referred to as "glycol component").

  Polyesters composed of these acid components and glycol components can be produced by arbitrarily using a commonly used method. For example, a transesterification reaction between a lower alkyl ester of an aromatic dicarboxylic acid and a glycol, or a direct esterification of an aromatic dicarboxylic acid and a glycol, to form a substantially bisglycol of an aromatic dicarboxylic acid A method is employed in which an ester or a low polymer thereof is formed and then polycondensed by heating under reduced pressure. Depending on the purpose, an aliphatic dicarboxylic acid may be copolymerized.

  Typical examples of the polyester used in the present invention include polyethylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, and the like. The polyester which copolymerized may be sufficient and may contain the other component and additive as needed. Of these, polyethylene terephthalate and polyethylene-2,6-naphthalate are preferably used.

As described above, the polyester includes inorganic particles such as calcium carbonate, kaolin, silica, aluminum oxide, titanium oxide, alumina, and barium sulfate, acrylic resin, guanamine resin, and the like for the purpose of improving the running property of the film. It is possible to contain organic particles such as fluororesin and precipitated particles obtained by making catalyst residual particles. The particles are blended in one of the two layers constituting the outermost layer of the biaxially stretched laminated polyester film of the present invention, more preferably in both. The particle size and amount of the particles can be appropriately determined according to the purpose.
In addition, various stabilizers, lubricants, antistatic agents, and the like can be added as appropriate.

-UV absorber-
Next, the ultraviolet absorber contained in the inner layer of the biaxially stretched laminated polyester film of the present invention will be described. In general, ultraviolet absorbers are compounds that have the property of absorbing ultraviolet rays and converting them into heat, and are classified into organic ultraviolet absorbers and inorganic ultraviolet absorbers, but can be contained in transparency and polyester. From the viewpoint, it is preferable to use an organic ultraviolet absorber in the present invention.
Examples of organic ultraviolet absorbers include benzotoazole, cyclic imino ester, benzophenone, salicylic acid, cyanoacrylate, and combinations thereof.

Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) -2H-benzotriazole and 2- (2′-hydroxy-5′-t-butylphenyl) -2H—. Benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -2H-benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) ) -2H-benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) -5-chloro-2H-benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-amyl) Phenyl) -2H-benzotriazole, 2- (2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl) -2H-benzotriazole, 2- (2′-hydroxy-5 ′-(methac) Liloyloxypropyl) phenyl) -2H-benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5 ′-(methacryloyloxyethyl) phenyl) -2H-benzotriazole, 2- (2′- Hydroxy-5'-t-butyl-3 '-(methacryloyloxyethyl) phenyl) -2H-benzotriazole, 2- (2'-hydroxy-5'-(methacryloyloxyethyl) phenyl) -5-chloro-2H- Although benzotriazole can be mentioned, it is not limited to these. Moreover, the thing with a large quantity which ultraviolet-ray absorption frame | skeleton dimerized via the methylene etc. like ADK STAB LA-31 (brand name of ADEKA Corporation) etc. is also preferable.
Among these, from the viewpoint of molecular weight, presence / absence of sublimation and compatibility with polyester, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -2H-benzotriazole, 2- (2 ′ -Hydroxy-3 ′, 5′-di-t-amylphenyl) -2H-benzotriazole, Adekastab LA-31 is preferred, 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) -2H-benzotriazole and ADK STAB LA-31 are more preferable.

  Examples of the cyclic imino ester-based ultraviolet absorber include the following. 2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one), 2-methyl-3,1-benzoxazin-4-one, 2-butyl-3, 1-benzoxazin-4-one, 2-phenyl-3,1-benzoxazin-4-one, 2- (1- or 2-naphthyl) -3,1-benzoxazin-4-one, 2- (4 -Biphenyl) -3,1-benzoxazin-4-one, 2-p-nitrophenyl-3,1-benzoxazin-4-one, 2-m-nitrophenyl-3,1-benzoxazin-4-one 2-p-benzoylphenyl-3,1-benzoxazin-4-one, 2-p-methoxyphenyl-3,1-benzoxazin-4-one, 2-o-methoxyphenyl-3,1-benzoxazine -4-one, 2 Cyclohexyl-3,1-benzoxazin-4-one, 2-p- (or m-) phthalimidophenyl-3,1-benzoxazin-4-one, 2,2 ′-(1,4-phenylene) bis ( 4H-3,1-benzoxazinon-4-one), 2,2′-bis (3,1-benzoxazin-4-one), 2,2′-ethylenebis (3,1-benzoxazine-4) -One), 2,2'-tetramethylenebis (3,1-benzoxazin-4-one), 2,2'-decamethylenebis (3,1-benzoxazin-4-one), 2,2 ' -P-phenylenebis (3,1-benzoxazin-4-one), 2,2'-m-phenylenebis (3,1-benzoxazin-4-one), 2,2 '-(4,4' -Diphenylene) bis (3,1-benzoxazi -4-one), 2,2 '-(2,6- or 1,5-naphthalene) 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-benzoxazine-4-one),

1,3,5-tri (3,1-benzoxazin-4-on-2-yl) benzene, 1,3,5-tri (3,1-benzoxazin-4-on-2-yl) naphthalene, And 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; 5,4-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; 5,4-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-benzoxazin-4-one), 6,6′-bis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6′-methyl Bis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6′-methylenebis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6′- Ethylenebis (2-methyl-4H, 3,1-benzoxazin-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 -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′-carbonylbis (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).
Among them, 2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one), 1,3 from the viewpoints of molecular weight, presence / absence of sublimation, compatibility with polyester, and the like. , 5-tri (3,1-benzoxazin-4-one-2-yl) benzene is preferred, and 2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinone-4- ON) is more preferable.

  Examples of the benzophenone ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2, 2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2, -hydroxy-4-methoxy-5-sulfobenzophenone and the like can be mentioned, and preferably 2-hydroxy -4-n-octyloxybenzophenone and 2-hydroxy-4-n-dodecyloxybenzophenone, more preferably 2-hydroxy-4-n-octyloxybenzophenone.

  Examples of salicylic acid-based ultraviolet absorbers include phenyl salicylate, pt-butylphenyl salicylate, pn-octylphenyl salicylate, and preferably pt-butylphenyl salicylate. , Pn-octylphenyl salicylate, more preferably pn-octylphenyl salicylate.

  Examples of cyanoacrylate-based ultraviolet absorbers include 2-ethylhexyl 2-cyano-3,3-diphenyl acrylate.

In addition, it is one of preferred embodiments of the present invention to use two or more kinds of ultraviolet absorbers in combination. From another point of view, it is preferable to use an ultraviolet absorber having a decomposition start temperature of 290 ° C. or higher in order to reduce process contamination during film formation.
Among the ultraviolet absorbers described above, benzotriazole type and cyclic imino ester type are particularly preferable from the viewpoint of durability. Specifically, ADK STAB LA-31 (manufactured by ADEKA Corporation), 2,2 ′-(1 , 4-Phenylene) bis (4H-3,1-benzoxazinon-4-one), 1,3,5-tri (3,1-benzoxazin-4-on-2-yl) benzene is preferred UV absorption Adecastab LA-31 and 2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one) are more preferable UV absorbers.

-Fluorescent whitening agent-
The inner layer of the biaxially stretched laminated polyester film of the present invention contains a fluorescent brightener in addition to the ultraviolet absorber. The fluorescent whitening agent used in the present invention can be arbitrarily selected from commercially available products or new substances from the viewpoint of durability and solubility. Specific examples (1) to (12) are listed below, but are not limited thereto.

  Among the compounds (1) to (12), the compound (3) is more preferably used.

  Another fluorescent brightener used in the present invention is represented by the following general formula (1).

In general formula (1), R ¹ and R ⁴ each independently represent a hydrogen atom, an alkyl group or an alkoxy group, and R ² and R ³ each independently represent an alkyl group. [A] represents a substituted aryl group or a substituted ethenyl group.

R ^{1 to} R ⁴ and [A] in the general formula (1) of the present invention will be described below.
R ¹ and R ⁴ each independently represents a hydrogen atom, an alkyl group or an alkoxy group, preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms. More preferably, they are a hydrogen atom or a C1-C8 alkyl group, More preferably, it is a hydrogen atom.
Specific examples of R ¹ and R ⁴ include a hydrogen atom, methyl group, ethyl group, n-propyl group, n-butyl group, n-octyl group, isopropyl group, isobutyl group, 2-ethylhexyl group, t-butyl group, t-amyl group, t-octyl group, cyclopentyl group, cyclohexyl group, methoxy group, ethoxy group, n-propoxy group, n-butoxy group, n-octyloxy group, isopropyloxy group, isobutyloxy group, 2-ethylhexyloxy Group, t-butoxy group, cyclohexyloxy group and the like.

R ² and R ³ each independently represents an alkyl group, preferably an alkyl group having 1 to 16 carbon atoms. Specific examples of R ² and R ³ include methyl group, ethyl group, n-butyl group, n-octyl group, n-hexadecyl group, isopropyl group, isobutyl group, 2-ethylhexyl group, t-butyl group, and t-amyl. Group, t-octyl group, cyclopentyl group, cyclohexyl group and the like.
R ² is preferably a methyl group, an isopropyl group, a t-butyl group, or a cyclohexyl group, and more preferably a t-butyl group or a cyclohexyl group.
R ³ is preferably a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-octyl group, an n-hexadecyl group or a 2-ethylhexyl group, more preferably a methyl group, an n-butyl group or an n-octyl group. Group or 2-ethylhexyl group.

  [A] represents a substituted aryl group or a substituted ethenyl group, preferably a substituted aryl group having 6 to 40 carbon atoms or a substituted ethenyl group having 8 to 40 carbon atoms. More preferred are substituted aryl groups or ethenyl groups represented by the following formulas (1-1) to (1-11).

In formulas (1-1) to (1-11), R ¹ ′, R ² ′, R ³ ′ and R ⁴ ′ have the same meaning as R ¹ , R ² , R ³ and R ⁴ in the general formula (1). is there. m represents an integer of 1 to 5. X and Y each represents an alkyl group, each independently an aryl group, an alkoxy group, an amino group, an alkylamino group, an arylamino group or a hydroxy group.

  More specifically, X and Y are, as an alkyl group, a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a cyclohexyl group, and the like, and as an aryl group, a phenyl group, a p-tolyl group, a 1-naphthyl group, and the like. , Alkoxy groups include methoxy group, ethoxy group, isopropoxy group, etc., and alkylamino groups include methylamino group, ethylamino group, octylamino group, dimethylamino group, N-methyl-N-ethylamino group, arylamino group, etc. Examples of the group include an anilino group and an N-methylanilino group. X and Y are preferably each independently an aryl group, an alkoxy group or an anilino group.

  Z represents a cyano group or an alkoxycarbonyl group.

  The compound represented by the general formula (1) is preferably a compound represented by the following general formula (2).

In general formula (2), R ⁵ and R ⁷ are each independently synonymous with R ² in general formula (1), and R ⁶ and R ⁸ are each independently in general formula (1). R ³ as synonymous. n represents 1 or 2. Among the above, R ⁵ and R ⁷ are methyl group, isopropyl group, t-butyl group, and cyclohexyl group, and R ⁶ and R ⁸ are methyl group, ethyl group, n-propyl group, n-butyl group, n -It is a case where it is an octyl group, n-hexadecyl group, and 2-ethylhexyl group, and n is 1 or 2. These compounds can be synthesized by the method described in JP-A-11-29556.

  Specific examples (13) to (30) of the compound represented by the general formula (2) are listed below, but the present invention is not limited thereto.

Among the compounds (13) to (30), the compounds (13), (15), (16),
(17), (19), (21), and (26) are preferable, and more preferably compound (13), (15), (16), (17), (19), or a combination thereof.

Further, a preferable combination of the ultraviolet absorber and the optical brightener contained in the polyester film of the present invention is a benzotriazole-based and / or cyclic iminoester-based as the ultraviolet absorber, and the general formula (1) and And / or a compound represented by (2), more specifically, a combination of ADK STAB LA-31 as an ultraviolet absorber and a compound (17) as a fluorescent whitening agent, and ADK STAB LA as an ultraviolet absorber. -31 and a combination of compound (3) and compound (16) as fluorescent brighteners, or 2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxa) as an ultraviolet absorber Dinon-4-one) and a combination of compound (3) and compound (17) as an optical brightener.
More preferable combinations include a combination of ADK STAB LA-31 as an ultraviolet absorber and compound (17) as a fluorescent brightener, ADK STAB LA-31 as a ultraviolet absorber, compound (3) and compound as a fluorescent brightener. In combination with (16) or 2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one) as an ultraviolet absorber and a compound ( 3) and a combination with compound (17).

In the film of the present invention, the amount of the fluorescent whitening agent and the ultraviolet absorber added to the polyester varies depending on the molecular weight, physical properties and properties of the fluorescent whitening agent and the ultraviolet absorber, but cannot be uniquely determined. And the total content of both needs to exist in the range of 0.1-9 mass% in the total solid of the composition which comprises the said polyester layer located as an inner layer. If this amount is less than 0.1% by mass, the UV blocking ability is insufficient. Conversely, if it exceeds 9% by mass, the molecular weight of the polyester is lowered and delamination occurs at the lamination interface, which is not preferable as a packaging film. . The total amount of the optical brightener and the ultraviolet absorber is preferably 0.3 to 9% by mass, more preferably 0.2 to 5% by mass.
The mixing ratio of the fluorescent whitening agent and the ultraviolet absorber is preferably in the range of 10/90 to 90/10 in terms of a molar ratio in terms of absorbing ultraviolet rays from short waves to long waves, and 30/70 to 70 / A range of 30 is preferred.

-Other ingredients-
The outer layer of the film of the present invention is provided for the purpose of protecting the inner layer, but the outer layer is provided with a crosslinking agent in order to improve its solvent resistance, water resistance, blocking resistance, and scratch resistance. It is preferably used for crosslinking and curing. Cross-linking agents include methylolated or alkylolized urea-based, melamine-based, guanamine-based, acrylamide-based, amide-based compounds, epoxy compounds, aziridine compounds, polyisocyanurates, block polyisocyanates, water-soluble polymers containing oxazoline groups , Silane coupling agents, titanium coupling agents, and zirco-aluminate coupling agents.
In addition, the outer layer contains inorganic and organic particles, a lubricant, an antistatic agent, an antifoaming agent and the like within a range not impairing the effects of the present invention in order to improve workability when forming the outer layer. You may let them.

  As a method for forming the outer layer on both sides of the inner layer, for example, a coating technique as shown in “Coating system” by Yuji Harasaki, Tsuji Shoten, published in 1979 can be used. Specifically, air doctor coater blade coater, rod coater, knife coater, squeeze coater, impregnation coater, reverse roll coater, transfer roll coater, gravure coater, kiss roll coater, cast coater, spray coater, curtain coater, calendar coater, Techniques such as extrusion coaters and bar coaters can be mentioned.

-Production of polyester film-
The film of the present invention is a laminated polyester film having at least three layers, in which an ultraviolet absorber and a fluorescent brightening agent are blended in the inner layer of the laminated structure, and the blending method varies depending on the purpose. A method of coextruding a polyester containing an ultraviolet absorber and a polyester containing no optical brightener and an ultraviolet absorber or containing a small amount of an optical brightener and an ultraviolet absorber is preferred. The outermost layer is preferably free of an ultraviolet absorber, but may be contained in a range that does not impair the process contamination and film characteristics.

  Although there is no restriction | limiting in the total thickness of the biaxially stretched laminated polyester film of this invention, when considering that it is used as a film for packaging, 6-75 micrometers is preferable. The thickness of the outermost layer is preferably in the range of 0.5 μm to 2/5 of the thickness of the entire film as the thickness on one side. If the thickness of the outermost layer is 0.5 μm or more, bleeding out of the optical brightener or ultraviolet absorber can be prevented, and if it is within 2/5 of the total thickness of the film, the fluorescent brightener and ultraviolet absorber are contained. It is possible to prevent delamination without excessive amounts of UV absorber in the layer to be formed.

As an example of the film forming method of the present invention, two types (I, II) of polyester are extruded from two extruders and laminated in two types and three layers (I / II / I) in the die. It is melt extruded and formed into a sheet on a cooling roll. The obtained sheet-like film is usually stretched 2 to 7 times at 60 to 120 ° C. by a roll stretching method to obtain a uniaxially stretched polyester film, and then usually in a direction perpendicular to the previous stretching direction in the tenter. A film forming method is preferred in which the film is stretched 2 to 7 times at 80 to 150 ° C. and further subjected to heat treatment at 150 to 250 ° C. for 1 to 600 seconds. As needed, you may apply | coat the easily bonding layer which consists of water-soluble or water-dispersible resin to the film after uniaxial stretching.
As described above, the biaxially stretched laminated polyester film of the present invention is excellent in ultraviolet blocking ability, can prevent yellowing of the film, and is excellent in transparency of the film. It can be suitably used for cosmetic packaging applications.

Next, the biaxially stretched laminated polyester film further having oxygen barrier properties according to the present invention will be described.
<Biaxially stretched laminated polyester film having oxygen barrier properties>
For the purpose of protecting the contents to be packaged with the film, an oxygen barrier layer can be further laminated on at least one surface of the biaxially stretched laminated polyester film of the present invention, thereby further providing oxygen barrier properties. it can. The oxygen permeability at this time is preferably 20 cc / m ² · day · atm or less as the biaxially stretched laminated polyester film as the final product. Depending on the contents of the packaging bag, discoloration or alteration can be prevented by providing an oxygen blocking layer even if the ultraviolet blocking is not complete. If the oxygen permeability is 20 cc / m ² · day · atm or less, discoloration and alteration of the contents can be prevented.

In the present invention, the method for imparting the oxygen barrier property is not particularly limited, but an aspect in which a layer made of a polymer compound or a layer made of a mixture of a polymer compound and an inorganic compound is additionally provided, A layer formed by depositing a metal oxide can be additionally provided. Examples of the polymer compound include resins having a permacol value of 75 cal / cc or more, such as polyvinyl alcohol (hereinafter referred to as “PVA”) resin or vinylidene chloride resin, and JP-A 2000-37822. Acrylic resins and the like described in Japanese Patent Publication No. Gazette can be mentioned, and among them, polyvinyl alcohol resins are preferable. Such an additional layer for imparting oxygen barrier properties (hereinafter also referred to as “oxygen barrier layer”) may be provided after the polyester film is formed, or may be provided when the polyester film is formed. . For example, in the sequential biaxial stretching method, there are a method of forming an oxygen barrier layer on a polyester film after longitudinal uniaxial stretching, then stretching it laterally and then heat-treating, and a method of forming an oxygen barrier layer after biaxial stretching. The latter method is a method employed when using a layer formed by depositing a metal oxide as the oxygen barrier layer.
The oxygen blocking layer additionally provided as described above may be formed on one surface of a film having a dedicated three-layer structure, or may be a layer interposed between the inner layer and the outer layer.

As the metal oxide, silicon oxide (SiO ₂ ) and / or aluminum oxide (Al ₂ O ₃ ) is preferable. These oxides may be provided by a vacuum deposition method. In the case of silicon oxide, a reactive silicon compound gas such as hexamethyldisiloxane and oxygen are introduced into a plasma state and reacted to form a polyester. You may provide by the method of providing on the film surface.

  An undercoat layer is provided in advance on the surface of the polyester film of the present invention so that the oxygen barrier layer provided in the present invention adheres well to the polyester film or the performance of the oxygen barrier layer can be sufficiently exerted, and oxygen is deposited thereon. It is preferable to provide a barrier layer. In particular, when the oxygen barrier layer is a metal oxide, it is preferable to have this undercoat layer. The undercoat layer of the present invention may be provided after the polyester film is formed, but is preferably provided at the time of forming the polyester film in consideration of cost. For example, in the sequential biaxial stretching method, there is a method in which a polyester film after longitudinal uniaxial stretching is coated with an undercoat layer, then stretched laterally and then heat-treated, or a method of coating and drying after a biaxially stretched film. Although there is no restriction | limiting in the said method, The method of coat | covering to a uniaxially-stretched polyester film, and then carrying out horizontal stretching and heat processing has the characteristics that an undercoat layer can be made thin uniformly, and is preferable.

  Such an undercoat layer is preferably an aqueous polymer which is dissolved, emulsified or suspended in water. For example, polyurethane resin, polyacrylic resin, polyester resin, epoxy resin, polyvinyl alcohol resin, polyvinylidene chloride Resin, polystyrene resin, polyvinyl pyrrolidone and copolymers thereof, but are not limited thereto. Moreover, these compounds can be used individually or in mixture of 2 or more types.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In addition, the evaluation method and the processing method of a sample in an Example and a comparative example are as follows. Further, “part” in Examples and Comparative Examples represents “part by mass”.
First, the biaxially stretched laminated polyester film according to the first embodiment of the present invention will be described with reference to Examples 1 to 4 and Comparative Example 1.

<Evaluation method>
(1) Film haze Film haze was measured by an integrating sphere turbidimeter NDH-20D (manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS-K7105.

(2) Light transmittance With a spectrophotometer UV3100 (manufactured by Shimadzu Corporation), the light transmittance is continuously measured in a scanning speed of 2 nm, a sampling pitch of 2 nm, and a wavelength of 300 to 700 nm, and wavelengths of 380 nm, 410 nm, and 430 nm. The light transmittance at was detected.

(3) Yellowness and transparency of film The yellowness and transparency of the film were confirmed by visual observation.

<Manufacture of polyester raw materials>
The polyester raw materials used in the following examples and comparative examples were produced by the following method. The intrinsic viscosity [η] (dl / g) of the polymer was measured at 30 ° C. using an Ubbelohde viscometer after dissolving 1 g of the polymer in 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (mass ratio). did.
-Manufacturing method of chip A-
A polyester chip having a melt viscosity of 0.66 containing 0.12 part of amorphous silica having an average particle size of 2.5 μm was obtained by a known melt polymerization method.

-Manufacturing method of chip B-
Chip A was subjected to a twin-screw extruder with a vent at an extrusion temperature of 290 ° C., and ADEKA STAB LA-31 (manufactured by ADEKA Corporation) as a benzotriazole-based ultraviolet absorber and compound (17) as a fluorescent brightening agent in mass A powder mixed at a ratio of 1/2 was supplied to a concentration of 10% by mass, melted and kneaded to form chips, and a master batch polyester chip (chip B) was produced. The intrinsic viscosity of the obtained polyester was 0.60.

-Manufacturing method of chip C-
The chip A was subjected to a vented twin screw extruder in the same manner as the chip B, and ADEKA STAB LA-31 (manufactured by ADEKA) as a benzotriazole-based UV absorber, and the compound (3) and the compound ( A powder obtained by mixing 16) at a mass ratio of 1/1/1 was supplied so as to have a concentration of 10% by mass, melt-kneaded to form chips, and a master batch polyester chip (chip C) was produced. The intrinsic viscosity of the obtained polyester was 0.59.

-Manufacturing method of chip D-
Chip A was subjected to a vented twin-screw extruder in the same manner as Chip B, and CYASORB UV-3638 (trade name, manufactured by Siatech, chemical name 2,2 ′-(1,4) as a cyclic iminoester ultraviolet absorber. -Phenylene) bis (4H-3,1-benzoxazinon-4-one)), a powder obtained by mixing Compound (3) and Compound (17) as a fluorescent brightening agent at a mass ratio of 1/1/1. A master batch polyester chip (chip D) was manufactured by supplying the composition so as to have a concentration by mass and melting and kneading it into chips. The intrinsic viscosity of the obtained polyester was 0.59.

<Manufacture of film>
The manufacturing method of the biaxially stretched laminated polyester film used in Examples and Comparative Examples and the biaxially stretched laminated polyester film having oxygen barrier properties will be described.
The thickness of the laminated polyester film was obtained by fixing a small piece of film with an epoxy resin, cutting it with a microtome, and observing the cross section of the film 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 layer thickness.

Example 1
Chip A is used as the raw material for the I layer, and the mixed raw material in which the chips A and B are mixed at a ratio of 90% and 10%, respectively, is supplied as the raw material for the II layer, and each is supplied to two extruders at 285 ° C. After melting, the I layer is the outer layer (outermost layer), the II layer is the inner layer (intermediate layer), and co-extruded in a two-layer, three-layer (I / II / I) layer configuration on a casting drum cooled to 40 ° C. Then, it was cooled and solidified to obtain a non-oriented sheet. Next, the film was stretched 3.5 times vertically at 85 to 100 ° C. to obtain a longitudinally uniaxially stretched film. This film was stretched 4.0 times horizontally in an atmosphere of 85 ° C. to 110 ° C. and then heat treated at 235 ° C. to obtain a biaxially stretched polyester film having a thickness of 16 μm. Each layer thickness of this laminated polyester film was 2 μm / 12 μm / 2 μm.
The light transmittance at 380 nm and 410 nm was 5% or less, and the light transmittance at 430 nm was 85% and the film haze was 4%. Further, the obtained film had no yellowness and was highly transparent. The evaluation results are shown in Table 1.

(Example 2)
A biaxially stretched polyester film having a thickness of 16 μm was obtained in the same manner as in Example 1 except that Chip A and Chip C were mixed at a ratio of 90% and 10%, respectively, as the raw material for the II layer. Each layer thickness of this laminated polyester film was 2 μm / 12 μm / 2 μm.
The light transmittance at 380 nm and 410 nm was 5% or less, and the light transmittance at 430 nm was 86% and the film haze was 4%. Further, the obtained film had no yellowness and was highly transparent. The evaluation results are shown in Table 1.

(Example 3)
A biaxially stretched polyester film having a thickness of 16 μm was obtained in the same manner as in Example 1 except that Chip A and Chip D were mixed at 90% and 10%, respectively, as the raw material for the II layer. Each layer thickness of this laminated polyester film was 2 μm / 12 μm / 2 μm.
The light transmittance at 380 nm and 410 nm was 5% or less, and the light transmittance at 430 nm was 84% and the film haze was 4%. Further, the obtained film had no yellowness and was highly transparent. The evaluation results are shown in Table 1.

Example 4
Chip A is used as the raw material for the I layer, and mixed raw materials obtained by mixing the chips A and B at a ratio of 80% and 20%, respectively, are used as the raw material for the II layer, and each is supplied to two extruders. After melting, the I layer is the outermost layer (surface layer), the II layer is the intermediate layer, and co-extruded in a layer configuration of 2 types and 3 layers (I / II / I) on a casting drum cooled to 40 ° C. and cooled and solidified. Thus, a non-oriented sheet was obtained. Next, the film was stretched 3.5 times vertically at 85 to 100 ° C. to obtain a longitudinally uniaxially stretched film. An aqueous medium coating containing 35, 30, 25, and 10 parts by mass of the resin a, resin b, resin c, and resin d described below was applied to this film on one side of the film. A biaxially stretched film having a film thickness of 16 μm and an undercoat layer thickness of 0.1 μm was obtained by stretching 40 times horizontally in an atmosphere of ° C. and then heat treating at 235 ° C. Each layer thickness of this laminated polyester film was 2 μm / 12 μm / 2 μm.
The light transmittance at 380 nm and 410 nm was 5% or less, and the light transmittance at 430 nm was 84% and the film haze was 4.2%. Further, the obtained film had no yellowness and was highly transparent. The evaluation results are shown in Table 1.

[Resin a: Aqueous acrylic resin]
A mixture of 40 parts by mass of ethyl acrylate, 30 parts by mass of methyl methacrylate, 20 parts by mass of methacrylic acid, and 10 parts by mass of glycidyl methacrylate was solution-polymerized in ethanol, and heated while adding water after polymerization to remove ethanol. The pH was adjusted to 7.5 with aqueous ammonia to obtain a coating solution (resin a) of an aqueous acrylic resin (non-emulsifier type).

[Resin b: Oxazoline group-containing water-soluble polymer solution]
Epocros WS-500 (water: 1-methoxy-2-propanol = 1: 2) manufactured by Nippon Shokubai Co., Ltd. was used.

[Resin c: water-based polyurethane-based resin water-based paint]
First, a polyester polyol composed of 664 parts by mass of terephthalic acid, 631 parts by mass of isophthalic acid, 472 parts by mass of 1,4-butanediol, and 447 parts by mass of neopentyl glycol was obtained. Next, 321 parts by mass of adipic acid and 268 parts by mass of dimethylolpropionic acid were added to the obtained polyester polyol to obtain a pendant carboxyl group-containing polyester polyol A. Further, 160 parts by mass of hexamethylene diisocyanate was added to 1880 parts by mass of the above polyester polyol A to obtain an aqueous polyurethane resin aqueous paint (resin c).

[Resin d: Water-dispersed polyester having a carboxyl group]
Polyester-WR-961 manufactured by Nippon Synthetic Chemical Industry was used.

<Manufacturing method of chip E>
Chip A was subjected to a vented twin-screw extruder in the same manner as Chip B, and CYASORB UV-3638 (manufactured by Siatech; chemical name 2,2 ′-(1,4-phenylene) as a cyclic iminoester-based ultraviolet absorber. Bis (4H-3,1-benzoxazinon-4-one)) was supplied to a concentration of 10% by mass, melt-kneaded to form chips, and a master batch polyester chip (chip E) was produced. . The intrinsic viscosity of the obtained polyester was 0.59.

(Comparative Example 1)
A biaxially stretched polyester film having a thickness of 16 μm was obtained in the same manner as in Example 1 except that the chip E was used instead of the chip B in Example 1. Each layer thickness of this laminated polyester film was 2 μm / 12 μm / 2 μm.
The light transmittance at 380 nm was 17%, the light transmittance at 410 nm was 82%, the light transmittance at 430 nm was 86%, and the film haze was 4%. Moreover, although the obtained film was highly transparent, it was yellowish. The evaluation results are shown in Table 1.

  As can be seen from Table 1, all of Examples 1 to 4 were able to suppress the light transmittance of 410 nm or less to 5% or less, but Comparative Example 1 was not able to cut ultraviolet rays of 410 nm or less. In Examples 1 to 4, the film had no yellowness and was highly transparent.

  Next, the biaxially stretched laminated polyester film having oxygen barrier properties will be described in accordance with Examples 5-7. The oxygen barrier rate of the film was measured at a temperature of 25 ° C. and a humidity of 60% by an isobaric method according to JIS K-7126.

(Example 5)
As a component of the oxygen barrier layer, polyvinyl alcohol (PVA) having a polymerization degree of 200 and a saponification degree of 95 mol% is gradually added and uniformly dispersed in hot water at 75 ° C., filtered, and then cooled. 20% PVA aqueous solution was prepared. In addition, 0.1% of Surfinol 440 (manufactured by Nissin Chemical Industry Co., Ltd.) was blended for the purpose of improving the coatability. One surface of the laminated polyester film produced in Example 2 was subjected to corona treatment, the wetting tension was set to 56 mN / m or more, and this PVA aqueous solution was applied to the surface to provide a PVA film having a layer thickness of 2 μm. The oxygen permeability of this film was 10 cc / m ² · day · atm. The evaluation results are shown in Table 2.

(Example 6)
On the surface of the undercoat layer of the laminated polyester film produced in Example 4, aluminum oxide (Al ₂ O ₃ ) was vapor-deposited as a component of the oxygen barrier layer so as to have a layer thickness of 20 nm to obtain a vapor-deposited film. The oxygen permeability of this film was 7 cc / m ² · day · atm. The evaluation results are shown in Table 2.

(Example 7)
On the surface of the undercoat layer of the laminated polyester film produced in Example 4, silicon oxide (SiO ₂ ) was vapor-deposited as a component of the oxygen barrier layer so as to have a layer thickness of 20 nm to obtain a vapor-deposited film. The oxygen permeability of this film was 3 cc / m ² · day · atm. The evaluation results are shown in Table 2.

  In Table 2, the oxygen permeability of the biaxially stretched laminated polyester film having oxygen barrier properties described in Examples 5 to 7 is shown together with the layer structure and each layer thickness of the film.

As can be seen from Table 2, as for the oxygen permeability of the film, all of the films of Examples 5 to 7 showed 10 cc / m ² · day · atm or less, and the film was difficult to transmit oxygen.

Claims (4)

  A laminated polyester film having at least three layers, wherein the inner layer of the laminated structure contains an ultraviolet absorber and a fluorescent brightening agent in a total amount of 0.1 to 9% by mass, and the light transmittance at a wavelength of 410 nm is 30% or less. A biaxially stretched laminated polyester film having a light transmittance at a wavelength of 430 nm of 70% or more.   The biaxially stretched laminated polyester film according to claim 1, wherein the ultraviolet absorber is at least one selected from benzotriazole-based and cyclic iminoester-based ultraviolet absorbers. The biaxially stretched laminated polyester film according to claim 1 or 2, wherein the fluorescent whitening agent is composed of a compound represented by the following general formula (1).

[In General Formula (1), R ¹ and R ⁴ each independently represent a hydrogen atom, an alkyl group or an alkoxy group, and R ² and R ³ each independently represent an alkyl group. [A] represents a substituted aryl group or a substituted ethenyl group. ] The biaxially stretched laminated polyester film according to any one of claims 1 to 3, further comprising a layer imparting oxygen barrier properties, and having an oxygen permeability of 20 cc / m ² · day · atm or less.