JP2004256625A - Polyester film for packaging - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a polyester film useful as a packaging material which excels in containment of oligomers, adhesion to a metal and a metal oxide, blocking resistance, scraping resistance, recovery properties, and does not change gas barrier properties even when subject to boiling treatment and retorting treatment. <P>SOLUTION: This polyester film for packaging is provided with a coating film by coating a coating fluid having (A) a polymeric resin having a glass transition temperature of 100°C to 160°C and (B) a crosslinking agent as the major constituting components on at least one surface of an aromatic polyester film, drying, and stretching the resulting film. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００６１】
続いてステンターに供給し、１２０℃にて横方向に３．７倍に延伸した。得られた２軸配向フィルムを２３５℃の温度で５秒間熱固定し、この間に１．５％幅弛緩し、更にフィルム温度が１００℃付近に低下したところで把持具から切り離して、塗膜を有するポリエステルフィルムを得た。乾燥後の塗膜の膜厚は０．０２μｍであった。得られたフィルムの評価結果を表２に示す。
【００６２】
【表２】

【００６３】
【発明の効果】
本発明によれば、オリゴマー封止性、金属及び金属酸化物接着性、耐ブロッキング性、耐削れ性、回収性に優れ、かつボイル処理、レトルト処理を受けてもガスバリア性、金属及び金属酸化物接着性に優れた特に包装用材料に有用なポリエステルフィルムを提供することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polyester film for packaging. More specifically, packaging materials, electronic materials, magnetic recording materials (for example, audio tapes) that require gas barrier properties and have excellent oligomer sealing properties, metal and metal oxide adhesion properties, blocking resistance, abrasion resistance, and recoverability. And a magnetic tape such as a video tape and a magnetic disk such as a floppy disk.
[0002]
[Prior art]
Polyester films, particularly polyethylene terephthalate films, are used as components of many flexible packaging films because of their advantages such as mechanical strength and thermal dimensional stability. Among them, foods and chemicals are spoiled and deteriorated by oxygen and water vapor, so they have an effect of blocking the intrusion of oxygen and water vapor from the outside air for long-term storage, so they have excellent gas barrier properties. Packaging must be done with materials. As a film having excellent gas barrier properties, a film obtained by laminating polyvinylidene chloride or an ethylene vinyl alcohol copolymer is known, and a film obtained by forming a metal oxide on a polymer film substrate is known. For example, a structure in which aluminum oxide is formed on a polyester film is known from Japanese Patent Publication No. 62-179935.
[0003]
However, those obtained by laminating polyvinylidene chloride or ethylene vinyl alcohol copolymer have poor heat resistance, and have a drawback that gas barrier properties are deteriorated by high-temperature moist heat treatment such as retort treatment. Furthermore, polyvinylidene chloride generates chlorine gas when incinerated, and there is a concern that it will affect the global environment.
[0004]
It is known from Japanese Patent Application Laid-Open No. 2000-108285 that when a metal oxide is formed on a polyester film, gas barrier properties are improved by reducing low molecular compounds or oligomers precipitated on the surface by heat treatment. However, when a polyester film is used as a base material, the polyester film generally has poor adhesion to a metal oxide, causes delamination at an interface, and has a disadvantage of deteriorating gas barrier properties.
[0005]
When packaging films are used for food packaging, boil treatment with hot water at about 100 ° C. and retort treatment with hot water at about 130 ° C. under high pressure are often performed for sterilizing foods. In Japanese Patent Application Laid-Open No. 8-31221, adhesion to metals and metal oxides in water is imparted by a coating layer composed of a mixture mainly composed of a polyester resin having a glass transition temperature of 0 to 80 ° C. and a melamine compound. However, it cannot cope with retort treatment with hot water at about 130 ° C. Further, in Japanese Patent Application Laid-Open No. 9-40904, it is possible to cope with boil treatment with a polyurethane resin, but it cannot withstand retort treatment. Japanese Patent Application Laid-Open No. 10-128936 also proposes a coating layer made of a polyester resin and / or a urethane resin, an acrylic resin, and an epoxy compound, but also cannot withstand retort treatment.
[0006]
In addition, if a scrap film that does not become a product (for example, an end of a film cut and removed from a product) is collected and used as a reclaimed material for film production, the coating film component contained in the reclaimed material during the melt-forming process may be thermally damaged. There is a problem that the film is deteriorated and the obtained film is markedly colored, which makes the film less practical (has poor recoverability). Further, there are defects such as difficulty in peeling the films from each other (blocking) and disadvantages in which the coating film is easily peeled.
[0007]
[Patent Document 1]
JP-B-62-179935
[0008]
[Patent Document 2]
JP 2000-108285 A
[0009]
[Patent Document 3]
JP-A-8-31221
[0010]
[Patent Document 4]
JP-A-9-40904
[0011]
[Patent Document 5]
JP-A-10-128936
[0012]
[Problems to be solved by the invention]
An object of the present invention is to solve the problems of the prior art, to have excellent oligomer sealing properties, metal and metal oxide adhesion, blocking resistance, abrasion resistance, and recoverability, and to undergo boil treatment and retort treatment. Another object of the present invention is to provide a polyester film for packaging excellent in gas barrier properties and adhesion to metals and metal oxides.
[0013]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that the above problems can be solved by forming a specific coating film, and have completed the present invention.
[0014]
That is, a coating liquid containing a polymer resin (A) having a glass transition temperature in the range of 100 ° C. to 160 ° C. and a crosslinking agent (B) as main components is applied to at least one surface of the aromatic polyester film, A polyester film for packaging, characterized by being provided with a coating film by drying and stretching.
[0015]
The present invention includes the following embodiments as preferred embodiments.
An embodiment in which the polymer resin (A) is a polyester resin.
An embodiment in which the crosslinking agent (B) is a water-soluble melamine crosslinking agent.
An embodiment in which the ratio between the polymer resin (A) and the crosslinking agent (B) satisfies the following formula (1).
A / B = 50/1 to 5/1 (1)
[0016]
An embodiment in which the amount of antimony in the aromatic polyester film is 10 mmol% or less based on all dicarboxylic acid components.
[0017]
Hereinafter, the present invention will be described in detail.
[0018]
[Aromatic polyester film]
In the present invention, the aromatic polyester constituting the aromatic polyester film is a linear saturated polyester comprising an aromatic dicarboxylic acid component and a glycol component. Examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, and 4,4′-diphenyldicarboxylic acid. Of these aromatic dicarboxylic acid components, terephthalic acid and 2,6-naphthalenedicarboxylic acid are particularly preferred in view of the mechanical properties of the film.
[0019]
Examples of the glycol component include ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, and polyethylene glycol. Among these glycol components, ethylene glycol is particularly preferred in view of the rigidity of the film.
[0020]
The aromatic polyester may be a copolyester obtained by copolymerizing a dicarboxylic acid component or a glycol component as a third component (a component other than the main component), and a trifunctional or higher polyvalent carboxylic acid component or a polyol component is obtained. The polyester which is copolymerized in a small amount in a range where the polyester becomes substantially linear (for example, 5 mol% or less) may be used.
[0021]
Such an aromatic polyester can be produced by a conventional method. When the intrinsic viscosity of the polyester (in ortho-chlorophenol, 35 ° C.) is 0.45 dl / g or more, the mechanical properties such as high rigidity of the film are improved. Therefore, it is preferable.
[0022]
Such aromatic polyesters can also contain colorants, antistatic agents, antioxidants, and organic lubricants.
[0023]
When the amount of antimony in the aromatic polyester of the film is 10 mmol% or less based on the total dicarboxylic acid components, the transparency of the film is preferably increased. For the same reason, the polycondensation metal catalyst residue in the aromatic polyester of the film is preferably less than 150 ppm.
[0024]
In the present invention, the aromatic polyester film is preferably a biaxially stretched film, and its thickness is preferably 1 μm or more, more preferably 5 to 500 μm, and particularly preferably 9 to 350 μm. If the thickness is less than 1 μm, the film is undesirably cut frequently when the film is formed. On the other hand, if it exceeds 500 μm, the film is too stiff and tends to have poor film-forming properties, which is not preferable.
[0025]
The aromatic polyester film may have a single-phase structure or a multilayer structure of two or more layers by a coextrusion method or the like.
[0026]
[Coating]
In the present invention, at least one surface of the aromatic polyester film is mainly composed of a polymer resin (A) having a secondary transition temperature (glass transition temperature) in the range of 100 ° C. to 160 ° C. and a crosslinking agent (B). A coating film formed by applying a coating liquid contained as a component, drying and stretching is provided. For this reason, the laminated film for packaging of the present invention is excellent in oligomer sealing property, metal and metal oxide adhesion, blocking resistance, abrasion resistance, recoverability, and even when subjected to boil treatment and retort treatment. Has barrier properties, metal and metal oxide adhesion.
[0027]
[Polymer resin (A)]
The polymer resin (A) is preferably a polyester resin from the viewpoint of adhesion to metals and metal oxides. As the polyester resin, a polyester obtained from the following polybasic acid component and diol component can be used. That is, as the polyvalent base component, for example, terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, Examples include pyromellitic acid, dimer acid, and 5-sodium sulfoisophthalic acid. As the polyester resin constituting the polymer binder, it is preferable to use a copolymerized polyester using two or more dicarboxylic acid components. The polyester resin may contain an unsaturated polybasic acid component such as maleic acid or itaconic acid, or a hydroxycarboxylic acid component such as p-hydroxybenzoic acid in a small amount. The main component of the acid component is preferably 2,6-naphthalenedicarboxylic acid in order to keep the glass transition temperature in the range of 100 to 160 ° C.
[0028]
In order to improve the hot water resistance, it is preferable that the polyester resin of the polymer resin (A) does not contain an acid component containing a sulfonic acid salt. It is preferable that no acid component is contained.
[0029]
In the polyester resin of the polymer resin (A), pyromellitic acid is particularly preferable as a copolymer component because of its excellent water dispersibility and recoverability. When pyromellitic acid is used, it is preferably in the range of 1 to 10 mol% of the total acid component. If it is less than 1%, there is no water dispersibility, and if it is more than 10%, the number of crosslinking points increases, and after collecting the film, foreign substances increase and the recoverability deteriorates.
[0030]
The polyester resin of the polymer resin (A) preferably contains a compound having a polyvalent carboxylic acid group as a copolymer component. In this case, after the copolymerization, an alkali metal compound or an amine compound is allowed to act to form the carboxylic acid. It is dispersed in water as an acid base.
[0031]
Examples of the diol component of the polyester resin of the polymer resin resin (A) include ethylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, and xylene glycol. , Dimethylolpropane, poly (ethylene oxide) glycol, and poly (tetramethylene oxide) glycol.
[0032]
The intrinsic viscosity of the polyester resin of the polymer resin (A) is preferably 0.4 or more and less than 0.7, and more preferably 0.5 or more and less than 0.7. When the intrinsic viscosity is less than 0.4, the molecular weight of the polyester resin is reduced, the cohesive force of the coating layer is reduced, and the adhesiveness is deteriorated. When the intrinsic viscosity is 0.7 or more, polymerization of the polyester resin becomes difficult, which is not preferable.
[0033]
The polyester resin of the polymer resin (A) can be produced, for example, by the following method. The dicarboxylic acid component and the diol component are charged into a transesterification reactor, a catalyst is added, and the produced methanol is distilled off by controlling the temperature at 230 ° C. under a nitrogen atmosphere to carry out a transesterification reaction. Next, the temperature is gradually raised to 255 ° C., and the polycondensation reaction is performed under reduced pressure in the system to obtain a polyester resin. When the molecular weight increases during polycondensation, the melt viscosity increases, and it becomes difficult to stir the system. The polyester resin used for the coating layer has a higher melt viscosity in spite of its lower molecular weight compared to homopolyethylene terephthalate, making it very difficult to stir the system, increasing the motor torque of the stirrer, and improving the shape of the blades. The intrinsic viscosity can be increased by devising or extending the polymerization time.
[0034]
The polyester resin of the polymer resin (A) is preferably a water-soluble or dispersible polyester resin, but a water-soluble polyester resin containing some organic solvent can also be used.
[0035]
[Crosslinking agent]
In the present invention, it is preferable to use a water-soluble melamine crosslinking agent as the crosslinking agent (B) from the viewpoint of improving the hot water resistance and improving the adhesion of the polymer resin (A) to metals and metal oxides.
[0036]
As the water-soluble melamine crosslinking agent, a compound obtained by reacting a methylol melamine derivative obtained by condensing melamine and formaldehyde with methyl alcohol, ethyl alcohol, isopropyl alcohol or the like as a lower alcohol, and a mixture thereof are preferable.
[0037]
Examples of the methylol melamine derivative include monomethylol melamine, dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, and hexamethylol melamine. In particular, water-soluble melamine is preferable because it is easily mixed with other resins, exists uniformly at the time of forming a coating film, and has good stretchability.
[0038]
The ratio of the polymer resin (A) to the crosslinking agent (B) in the coating film of the present invention is preferably in the range of A / B = 50/1 to 5/1, and A / B = 40/1 to 10/1. Is more preferable. When the ratio of A / B is more than 50/1, the degree of cross-linking becomes low, and the oligomer sealing property and hot water resistance are deteriorated, which is not preferable. If the ratio of A / B is less than 5/1, the degree of cross-linking is increased, foreign matter during film recovery increases, and the recoverability deteriorates, which is not preferable.
[0039]
In the coating liquid for forming the coating film in the present invention, a polymer resin other than the above may be blended in order to adjust the adhesiveness between the coating film and the polyester film. Examples of such a polymer resin include an acrylic resin, a polyurethane resin, an epoxy resin, a vinyl resin, a polyether resin, and a water-soluble resin.
[0040]
Similarly, a crosslinking agent other than the above can be blended to adjust the adhesiveness. Examples of such a crosslinking agent include epoxy, oxazoline, isocyanate, and coupling agent.
[0041]
The coating liquid for forming a coating film in the present invention includes a surfactant (C) to improve the stability of the coating liquid, particularly an aqueous coating liquid, and to improve the wettability when applying the coating liquid to a polyester film. Can be blended. Examples of the surfactant (C) include nonionic surfactants such as alkylene oxide homopolymers, alkylene oxide copolymers, aliphatic alcohol / alkylene oxide adducts, polyhydric alcohol fatty acid esters, and long-chain aliphatic amide alcohols. Examples thereof include cationic or anionic surfactants such as compounds having a quaternary ammonium salt, compounds having an alkylpyridinium salt, and compounds having a sulfonate, and nonionic surfactants are particularly preferable.
[0042]
The solid content concentration of the coating liquid in the present invention is preferably 0.5 to 30% by weight. If the solid content is less than 0.5% by weight, the wettability to the polyester film is insufficient, and if it exceeds 30% by weight, the appearance of the coating tends to deteriorate. The main constituent of the coating liquid means that the proportion of the solid content in the coating liquid is, for example, 50% by weight or more, preferably 70% by weight or more.
[0043]
[Production method]
In the present invention, the coating liquid containing each of the above components is applied to at least one surface of the aromatic polyester film. As the aromatic polyester film, a polyester film before the completion of the oriented crystal is preferable. As the polyester film before the completion of the oriented crystal, an unstretched film obtained by directly melting the polyester to form a film, a uniaxially stretched film in which the unstretched film is oriented in either the longitudinal direction or the transverse direction, An example is a biaxially stretched film that has been stretched and oriented at a low magnification in two directions, that is, a longitudinal direction and a lateral direction (finally, it is stretched again in a longitudinal direction and a lateral direction to complete oriented crystallization).
[0044]
[Coating method]
As a method for applying the coating liquid to the aromatic polyester film, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a microgravure coating method, a reverse coating method, a roll brush method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, or the like may be applied alone or in combination. When an aqueous coating liquid is used, a slight amount of an organic solvent may be contained for the purpose of assisting the stability of the coating liquid.
[0045]
Coating amount is 1m of running film ² The weight is preferably 0.5 to 50 g, more preferably 5 to 30 g. The thickness of the final dried coating film is preferably from 0.01 to 1 μm, and more preferably from 0.01 to 0.8 μm. When the thickness of the coating film is less than 0.01 μm, the adhesion to metal and metal oxide becomes insufficient, and when it exceeds 1 μm, the blocking resistance tends to decrease. Coating can be performed on only one side or both sides depending on the use of the film. After coating, the coating is dried to form a uniform coating.
[0046]
In the present invention, after applying the coating liquid to the polyester film, it is preferable to perform drying, preferably stretching treatment, but it is preferable to perform drying at 90 to 130 ° C. for 2 to 20 seconds. Drying can also serve as a residual heat treatment of the stretching treatment or a heat treatment at the time of stretching. The stretching of the polyester film is performed at a temperature of 70 to 140 ° C. in the longitudinal direction by 2.5 to 7 times, in the transverse direction by 2.5 to 7 times, and in an area magnification of 8 times or more, and more preferably 9 to 28 times. preferable. When re-stretching, it is preferable to stretch at a magnification of 1.05 to 3 times (however, the area magnification is the same as described above). The heat setting after the stretching is preferably performed at a temperature higher than the final stretching temperature and lower than the melting point for 1 to 30 seconds. For example, in the case of a polyethylene terephthalate film, it is preferable to heat set at 170 to 240 ° C. for 2 to 30 seconds.
[0047]
The polyester film thus obtained has excellent oligomer sealing properties, metal and metal oxide adhesion, blocking resistance, abrasion resistance, and recoverability, and has a barrier property even when subjected to boil treatment and retort treatment, metal and metal. It has excellent oxide adhesion and is extremely useful as a film for packaging materials.
[0048]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples. The evaluation in the present invention was performed by the following method.
[0049]
(1) Oligomer sealing property
The sample film cut into a size of 150 mm × 100 mm was subjected to a heat treatment at 150 ° C. for 1 hour with a drier, and was then allowed to stand with sufficient care so that a finger or the like did not touch the surface of the sample film to cool to room temperature. The surface of the obtained sample film was observed under a microscope (reflection, magnification: 50 times, 200 times), and the oligomer sealing property was evaluated according to the following criteria.
：: No generation of oligomer (good oligomer sealing property)
：: Oligomer is slightly generated (oligomer sealing property is slightly good)
×: A large amount of oligomer is generated (poor oligomer sealing property)
[0050]
(2) Adhesiveness
・ Normal temperature adhesion
Al deposition is performed on the coated surface of the sample film cut into a size of 250 mm × 150 mm. Next, an epoxy-based adhesive is applied to the Al-deposited surface, a 50 μm-thick polyethylene terephthalate film is laminated thereon, and laminated at a temperature of 80 ° C., a speed of 60 m / min, and a nip pressure of 3.0 bar. After aging the obtained laminate sample at 60 ° C. for 48 hours, the laminated film was peeled off with an epoxy-based adhesive, and the peeling force was measured to evaluate the laminate according to the following criteria.
・ Adhesiveness after boiling treatment
The laminated sample after aging for 48 hours was subjected to a boil treatment (100 ° C., 30 minutes), the laminated film was peeled off with an epoxy-based adhesive, and the peeling force was measured to evaluate according to the following criteria.
・ Adhesion after retort treatment
The laminated sample after aging for 48 hours was subjected to a boil treatment (125 ° C., 30 minutes), the bonded film was peeled off with an epoxy-based adhesive, and the peeling force was measured to evaluate according to the following criteria.
◎: N / 5 cm <peel force (adhesiveness is very good)
：: N / 5cm <peeling force ≦ N / 5cm (good adhesion)
Δ: N / 5cm <peeling force ≦ N / 5cm (adhesion is slightly good)
×: Peeling force ≦ N / 5cm (poor adhesion)
[0051]
(3) Gas barrier properties
The oxygen permeability (JIS K7126) and the water vapor permeability (JIS K7129) of the sample prepared in the evaluation of adhesiveness, the sample subjected to the boil treatment and the retort treatment were measured in accordance with JIS standards, and evaluated according to the following criteria.
・ Oxygen permeability
A: Oxygen permeability <0.5 cc / m ² ・ 24h ・ atm
：: 0.5 cc / m ² ・ 24h ・ atm ≦ oxygen permeability <1.0cc / m ² ・ 24h ・ atm
Δ: 1.0 cc / m ² ・ 24h ・ atm ≦ oxygen permeability <5.0cc / m ² ・ 24h ・ atm
×: 5.0 cc / m ² ・ 24h ・ atm ≦ oxygen permeability
・ Water vapor permeability
◎: water vapor permeability <0.5 g / m ² ・ 24h
：: 0.5 g / m ² ・ 24h ≦ water vapor permeability <1.0g / m ² ・ 24h
Δ: 1.0 g / m ² ・ 24h ≦ water vapor permeability <5.0 g / m ² ・ 24h
×: 5.0 g / m ² ・ 24h ≦ water vapor permeability
[0052]
(4) Collectability
The film without the coating film was pulverized, melted at about 300 ° C. with an extruder and formed into chips. Next, a melt film was formed using the obtained chips to prepare a blank film. The coloring degree of this film was defined as a blank. On the other hand, the sample film provided with the coating film was pulverized, melted at about 300 ° C. by an extruder and formed into chips. Subsequently, a melt film was formed using the obtained chips to produce a recycled film. The coloring degree of this film was evaluated according to the following criteria.
：: Coloring degree is equivalent to that of blank film and there is no foreign matter (recoverability is very good)
：: The film is slightly colored or a foreign substance is slightly present (good recoverability)
×: The film has a high degree of coloring or a large amount of foreign substances, and lacks practicality (poor recoverability)
[0053]
(5) Intrinsic viscosity
Intrinsic viscosity ([η] dl / g) was measured with an o-chlorophenol solution at 25 ° C.
[0054]
(6) Glass transition temperature
About 10 mg of the sample was sealed in an aluminum pan for measurement, attached to a differential calorimeter (V4.OB2000 type DSC manufactured by DuPont), and heated from 25 ° C. to 300 ° C. at a rate of 20 ° C./min. After keeping at 5 ° C. for 5 minutes, remove, immediately transfer to ice and quench. The pan is mounted on the differential calorimeter again, and the temperature is raised from 25 ° C. at a rate of 20 ° C./min to measure the glass transition temperature (Tg: ° C.).
[0055]
(7) Solid composition of aqueous coating liquid
Polymer resin 1:
The acid component is composed of 2,6-naphthalenedicarboxylic acid mole 90% / isophthalic acid 5 mole% / pyromellitic acid 5 mole%, and the glycol component is ethylene glycol 90 mole% / diethylene glycol 10 mole% (Tg = 110 ° C.). , Average molecular weight 13000). The polymer resin was produced according to the method described in JP-A-60-209073, JP-A-53-98336, and JP-A-56-116718.
[0056]
Polymer resin 2:
The acid component is composed of 66 mol% of terephthalic acid / 14 mol% of isophthalic acid / 20 mol% of trimellitic acid, and the glycol component is composed of 30 mol% of ethylene glycol / 35 mol% of neopentyl glycol and 35 mol% of 1,4-butanediol. (Tg = 20 ° C., average molecular weight 12000). The polymer resin 2 was produced according to the method described in JP-A-60-209073, JP-A-53-98336, and JP-A-56-116718.
[0057]
Polymer resin 3:
The acid component is composed of 60 mol% of terephthalic acid / 30 mol% of isophthalic acid / 5 mol% of 5-sodium sulfoisophthalic acid, and the glycol component is composed of 90 mol% of ethylene glycol / 10 mol% of diethylene glycol (Tg = 45 ° C., average Molecular weight 14000). In addition, the polymer resin 3 was manufactured according to the method described in Example 1 of JP-A-06-116487.
[0058]
Crosslinking agent: Methylolated melamine (trade name MX-035, manufactured by Sanwa Chemical Co., Ltd.)
Wetting agent: polyoxyethylene (n = 7) lauryl ether (Naroacty N-70, manufactured by Sanyo Chemical Industries, Ltd.)
[0059]
[Examples 1 and 2, Comparative Examples 1 to 3]
Dimethyl terephthalate and ethylene glycol, manganese acetate as a transesterification catalyst, germanium oxide as a polymerization catalyst, phosphorous acid as a stabilizer, and a porous silica particle having an average particle size of 0.9 μm as a lubricant as a polymer are polymerized. And polymerized by a conventional method to obtain polyethylene terephthalate (Tg: 78 ° C.) having an intrinsic viscosity (orthochlorophenol, 35 ° C.) of 0.64 dl / g. This polyethylene terephthalate pellet was dried at 170 ° C. for 3 hours, melted at a melting temperature of 295 ° C. by an extruder, filtered by a nonwoven fabric filter, extruded from a slit die onto a rotating cooling drum having a surface temperature of 20 ° C. A stretched film was obtained. Subsequently, the unstretched film was preheated to 75 ° C., stretched 3.6 times in the machine direction by heating between a low-speed roller and a high-speed roller, and quenched. A weight% aqueous coating solution was applied to one surface of the above film using a roll coater.
[0060]
[Table 1]

[0061]
Subsequently, it was supplied to a stenter and stretched 3.7 times in the horizontal direction at 120 ° C. The obtained biaxially oriented film was heat-set at a temperature of 235 ° C. for 5 seconds, during which the width was relaxed by 1.5%, and when the film temperature dropped to around 100 ° C., the film was cut off from the gripper to have a coating film. A polyester film was obtained. The thickness of the dried coating film was 0.02 μm. Table 2 shows the evaluation results of the obtained films.
[0062]
[Table 2]

[0063]
【The invention's effect】
Advantageous Effects of Invention According to the present invention, oligomer sealing properties, metal and metal oxide adhesion, blocking resistance, abrasion resistance, excellent recoverability, and gas barrier properties even when subjected to boil treatment and retort treatment, metal and metal oxides It is possible to provide a polyester film having excellent adhesiveness and particularly useful as a packaging material.

Claims (5)

On at least one surface of the aromatic polyester film, a coating liquid containing a polymer resin (A) having a glass transition temperature in a range of 100 ° C. to 160 ° C. and a crosslinking agent (B) as main components is applied, dried, and dried. A polyester film for packaging, which is provided with a coating film by stretching. The packaging polyester film according to claim 1, wherein the polymer resin (A) is a polyester resin. The polyester film for packaging according to claim 1, wherein the crosslinking agent (B) is a water-soluble melamine crosslinking agent. The packaging polyester film according to claim 1, wherein the ratio of the polymer resin (A) and the crosslinking agent (B) satisfies the following formula (1).
A / B = 50/1 to 5/1 (1) The polyester film for packaging according to claim 1, wherein the amount of antimony in the aromatic polyester film is 10 mmol% or less based on all dicarboxylic acid components.