JP5142421B2 - Biaxially oriented polyethylene terephthalate film for transparent deposition - Google Patents

Description

【００５６】
【表２】

【００５７】
【発明の効果】
本発明によって得られた透明蒸着ポリエステルフィルムは、薄い蒸着膜厚さで高いガスバリア性能を安定して付与でき、かつ蒸着膜の密着性が良く、高い生産性を得られるという特徴を持つ。
【００５８】
本発明によって得られた透明蒸着ポリエステルフィルムは、単独でも用いることができるが、更に、印刷を施したり、蒸着膜の上から保護層などをコーティングしたり、ヒートシール層を積層したり、他のフイルムと積層したり、あるいはこれらを組み合わせたりするなど、更に加工して用いることもできる。また、非蒸着面にヒートシール層を積層したり、他のフイルムと積層したり、あるいはこれらを組み合わせたりすることもできる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transparent deposition polyester film and a transparent deposition polyester film.
[0002]
[Prior art]
In order to store food and medicines for a long period of time, it is necessary to perform packaging that has the effect of blocking the entry of oxygen and water vapor from the outside in order to prevent spoilage and deterioration. In recent years, a film packaging excellent in gas barrier used for this purpose is required to have a transparency that can particularly confirm the state of the contents.
[0003]
A transparent gas barrier film in which polyvinylidene chloride or ethylene vinyl alcohol copolymer is laminated is known. However, the barrier property of oxygen / water vapor is not sufficient, and the deterioration thereof is remarkable particularly in sterilization treatment at high temperature. In addition, polyvinylidene chloride generates chlorine-based gas during incineration, and it has been pointed out that corrosion of the incinerator and adverse effects on the global environment have been pointed out, and that the burden on the incinerator for purifying exhaust gas is also large. .
[0004]
As a packaging film that solves these problems, a transparent vapor-deposited film formed with a silicon oxide or aluminum oxide film exhibits good barrier properties. However, the boil / retort treatment lowers the gas barrier properties and the adhesion of the vapor-deposited film. There was a problem.
[0005]
[Problems to be solved by the invention]
The present invention aims to solve the above-described problems. That is, an object of the present invention is to provide a transparent vapor-deposited polyester film and a transparent vapor-deposited polyester film that are excellent in oxygen and water vapor barrier properties and excellent in adhesion between the vapor-deposited film and the polyester film and suitable for boil / retort treatment. .
[0006]
[Means for Solving the Problems]
The present invention is a biaxially oriented polyethylene terephthalate film for transparent vapor deposition characterized by satisfying the following formulas (1) to ( 8 ) and containing silicon dioxide particles.
0.160 ≦ fn ≦ 0.180 (1)
1.495 ≦ nZD ≦ 1.505 (2)
250 MPa ≤ Y150 (3)
215 ° C ≦ Tmeta ≦ 231 ℃ (4)
25 equivalents / ton ≦ COOH ≦ 60 equivalents / ton (5)
Tmeta ≧ 245−0.5 × COOH (6)
5nm ≤ SRa ≤ 80nm (7)
10 / 0.1mm ² ≤ SPc ≤ 130 / 0.1mm ² (8)
fn: Planar orientation coefficient nZD: Refractive index in the thickness direction Y150: Young's modulus in the longitudinal direction under an atmosphere of 150 ° C. Tmeta: Melting sub-peak of the film COOH: Amount of carboxyl end groups of the film
SRa: Centerline surface roughness
SPc: Number of mountains
DETAILED DESCRIPTION OF THE INVENTION
The polyester of the polyester film referred to in the present invention is preferably one having an ethylene terephthalate unit as a main component from the viewpoint of an ester bond. Hereinafter, the polyester referred to in the present invention is read as polyethylene terephthalate.
[0008]
In the polyester resin used in the present invention, for example, an aromatic dicarboxylic acid of terephthalic acid can be used as the acid component. On the other hand, for example, an aliphatic diol of ethylene glycol can be used as the alcohol component. Furthermore, polyethers such as polyethylene glycol and polytetramethylene glycol may be copolymerized. Two or more layers may be used as a co-extruded laminated film.
[0009]
In addition, known additives such as heat stabilizers, oxidation stabilizers, weathering stabilizers, UV absorbers, organic lubricants, pigments, dyes, fillers, antistatic agents, nuclei An agent or the like may be blended. The intrinsic viscosity (measured in an orthochlorophenol at 25 ° C.) of the polyester resin as described above is preferably 0.40 to 1.20, more preferably 0.50 to 0.80, and still more preferably 0. The range is from 55 to 0.75 dl / g. Furthermore, the amount of carboxyl terminal groups of the polyester film serving as the base material is 25 to 60 equivalent / ton, preferably 35 equivalent / ton to 45 equivalent / ton, from the viewpoint of adhesion to the deposited film. When the carboxyl end group amount is less than 25 equivalents / ton, the adhesion with the deposited film is lowered, which is not preferable. On the other hand, when the carboxyl end group amount exceeds 60 equivalents / ton, it is not preferable because the coloration or the film forming property of the polyester film deteriorates.
[0010]
The diameters of the various particles used are not particularly limited, but the average particle diameter measured by the precipitation method or light scattering method is usually 0.05 to 8.0 μm, preferably 0.1 to 4.0 μm. be able to.
[0011]
Furthermore, the film of the present invention may be subjected to various coatings, and is not particularly limited. However, in consideration of production and environmental aspects, a film obtained by applying an aqueous or water-dispersed coating agent during film formation is preferable.
[0012]
The polyester film of the present invention needs to be biaxially oriented. A biaxially oriented polyester film is produced by stretching a non-stretched polyester sheet or film in a so-called biaxial direction in the longitudinal direction and the width direction, and forming a biaxially oriented pattern by wide-angle X-ray diffraction. Say what you indicate. The biaxial stretching method may be either sequential biaxial stretching or simultaneous biaxial stretching, but simultaneous biaxial stretching is desirable because scratches are unlikely to occur on the film surface.
[0013]
The thickness of the biaxially oriented polyester film of the present invention is not particularly limited, but is usually 0.5 to 500 μm, preferably 1 to 300 μm, and more preferably 4 to 30 μm.
[0014]
The film structure may be a single layer, two layers of A / B, three layers of A / B / A or A / B / C, and a multilayer structure that is more multilayer than three layers, and the lamination thickness ratio is also arbitrary. May be set to Furthermore, layers other than these may be laminated, and specific examples include an antistatic layer, a mat layer, a hard coat layer, a slippery coat layer, an easy adhesion layer, and an adhesive layer.
[0015]
In the polyester film of the present invention, the plane orientation coefficient (fn) needs to be 0.160 to 0.180, preferably 0.163 to 0.175. When the plane orientation coefficient (fn) is less than 0.160, the rigidity of the film is lost, the workability is deteriorated, and the gas barrier property of the polyester film itself is deteriorated. Further, if the plane orientation coefficient (fn) exceeds 0.180, the adhesion with the deposited film is lowered, which is not preferable.
[0016]
In the polyester film of the present invention, the refractive index (nZD) in the thickness direction needs to be 1.495 to 1.505. If the refractive index (nZD) in the thickness direction is less than 1.495, problems such as deterioration in adhesion to the deposited film and reduction in strength of the packaging material due to cleavage of the film are not preferable. On the other hand, if it exceeds 1.505, the processing characteristics and productivity deteriorate, which is not preferable.
[0017]
In the polyester film of the present invention, the Young's modulus in the longitudinal direction under an atmosphere of 150 ° C. needs to be 200 MPa or more, preferably 230 MPa or more, more preferably 250 MPa or more. If the Young's modulus in the longitudinal direction under an atmosphere of 150 ° C. is less than 200 MPa, it tends to extend with respect to the external force at the time of vapor deposition processing, which is not desirable because workability deteriorates. The upper limit is not particularly specified, but is usually about 400 MPa.
[0018]
In the polyester film of the present invention, the melting subpeak (Tmeta) of the film needs to be 215 to 240 ° C, preferably 225 to 235 ° C. If Tmeta is less than 215 ° C., the thermal dimensional stability at high temperatures deteriorates, which is not preferable. Further, if Tmeta exceeds 240 ° C., the film becomes brittle, which is not preferable.
[0019]
In the polyester film of the present invention, the relationship between the film melting subpeak (Tmeta) and the amount of carboxyl end groups (COOH) needs to be Tmeta ≧ 245−0.5 × COOH. The adhesion of the deposited film is better as the amount of carboxyl end groups is larger and the melting subpeak of the film is higher. When the melting subpeak of the film is in the range of Tmeta <245-0.5 × COOH, the adhesion between the deposited film and the polyester film is not sufficient, and problems such as delamination occur, which is not preferable.
[0020]
In the polyester film of the present invention, the film surface oligomer amount is preferably 60 mg / m ² or less, more preferably 50 mg / m ² or less. When the amount of oligomer on the surface of the film is 60 mg / m ² or more, the oligomer deposited on the surface causes a vapor deposition film defect and deteriorates the gas barrier property. The lower limit of the film surface oligomer amount is not particularly limited, but is usually about 20 mg / m ² .
[0021]
In the polyester film of the present invention, the center line surface roughness (SRa) of the vapor deposition surface side surface is preferably 5 to 80 nm, more preferably 10 to 50 nm. If SRa is less than 5 nm, there is a problem that slipping is poor and the film cannot be wound on a roll. If SRa exceeds 80 nm, the gas barrier property and moisture resistance after vapor deposition deteriorate. This SRa is a parameter of a three-dimensional surface roughness and is a center plane average roughness. Further, the number of peaks (SPc) on the vapor deposition surface side is preferably 10 to 150 / 0.1 mm ² , more preferably 30 to 130 / 0.1 mm ² . If the SPc is less than 10 pieces / 0.1 mm ² , there is a problem that slipping is worsened and the film cannot be wound on a roll. When SPc exceeds 150 / 0.1 mm ² , the gas barrier properties after vapor deposition deteriorate. This SPc is a parameter of three-dimensional surface roughness and is the number of peaks. A plane parallel to the center plane of the roughness curved surface is provided above and below the center plane, and the number of peaks recognized as peaks on both the upper and lower planes is measured and converted into a specified area.
[0022]
In the polyester film of the present invention, the film haze is preferably 5.0% or less, more preferably 3.0% or less. If the haze exceeds 5.0%, the visibility of the contents deteriorates, which is not preferable. The film haze has no particular lower limit, but is usually about 0.1%.
[0023]
The film surface of the present invention may be subjected to a known surface treatment, that is, a low temperature plasma treatment, a corona discharge treatment or the like, and the wetting tension of the vapor deposition surface is desirably 50 mN / m or more. Although there is no upper limit in particular, it is usually about 58 mN / m.
[0024]
As a transparent vapor deposition layer provided in the polyester film of this invention, the metal oxide represented by the silicon oxide film and the aluminum oxide can be mentioned. Although the thickness of a vapor deposition layer is not specifically limited, 5-150 nm is suitable from productivity, handling property, and external appearance.
[0025]
Next, although the typical manufacturing method of the vapor deposition biaxially-oriented polyester film of this invention is demonstrated, it is not specifically limited to this.
[0026]
In the polymerization stage, the amount of carboxyl end groups (COOH) is adjusted, and the resin containing precipitated particles, inorganic particles or organic particles (resin that should constitute a biaxially oriented polyester film) is dried under predetermined conditions, After being melted by the above method, it is formed into a film (usually on a cooling drum). This film is heated to 75 to 130 ° C. and stretched 2.0 to 9.0 times in the longitudinal direction to form a uniaxially oriented film. While this uniaxially oriented film is heated to 75 to 130 ° C., it is stretched 2.0 to 9.0 times in the width direction, and subsequently introduced into a heat treatment zone at 170 to 240 ° C. and heat treated for 1 to 10 seconds. . During this heat treatment, a relaxation treatment of 0 to 12% in the width direction may be performed as necessary. Further, the ends in the longitudinal direction and the width direction may be gripped with a clip and simultaneously biaxially stretched. Simultaneous biaxial stretching is desirable because scratches are less likely to occur on the film surface.
[0027]
A vapor-deposited layer is provided on the biaxially oriented polyester film thus obtained. A vacuum process is used to provide a deposited metal film. Typical examples of the vacuum process include a vacuum deposition method, a sputtering method, and an ion plating method. A preferable method includes a vacuum deposition method.
[0028]
A vacuum process is used to provide a deposited metal oxide film. As a vacuum process, a vacuum deposition method, a sputtering method, an ion plating method, a chemical vapor deposition method, or the like is appropriately used, and any of them is not limited, but a reactive deposition method is preferably used in terms of productivity and cost. it can. To deposit aluminum oxide in reactive vapor deposition, aluminum metal and alumina are evaporated by resistance heating boat method, high frequency induction heating of crucible, electron beam heating method, and oxidized on biaxially oriented polyester film under oxidizing atmosphere. A method of depositing aluminum is adopted. As a reactive gas for forming an oxidizing atmosphere, water or a rare gas may be added mainly with oxygen. Furthermore, a method of promoting a reaction such as adding ozone or ion assist may be employed. It is more preferable to use a plasma treatment on the surface of the biaxially oriented polyester film in these vacuum processes because gas barrier properties and moisture permeability are improved.
[0029]
In order to deposit silicon oxide by the reactive evaporation method, a method of evaporating Si metal, SiO or SiO ₂ by an electron beam heating method, and depositing silicon oxide on a biaxially oriented polyester film in an oxidizing atmosphere is adopted. . The method described above is used as a method of forming the oxidizing atmosphere.
[0030]
[Method for measuring characteristic values]
The characteristic value measurement method and effect evaluation method of the present invention are as follows.
[0031]
(1) Refractive index, plane orientation coefficient Measured with an Abbe refractometer using sodium D-line (wavelength 589 nm) as a light source. The plane orientation coefficient was obtained by calculating fn = (nMD + nTD) / 2−nZD from the refractive indexes (nMD, nTD, nZD) in the longitudinal direction, the width direction, and the thickness direction.
[0032]
(2) An SS curve was obtained using a Tensilon (tensile tester) in an atmosphere with a Young's modulus of 150 ° C. with a pulling speed of 200 mm / min, a width of 10 mm, and a sample length of 100 mm. The elastic modulus was obtained from the linear equation of the tangent of the maximum slope of the SS curve within 1% elongation in the obtained SS curve, and the Young's modulus was obtained.
[0033]
(3) Film melting sub-peak (Tmeta)
The film was measured with a differential scanning calorimeter (DSC-2 type, manufactured by Perkin Elmer Co.) at a heating rate of 20 ° C./min. The sub-peak temperature generated by the transformation of the pseudo crystal observed by this measurement was defined as Tmeta. Tmeta appears as a history of the heat treatment temperature during the film forming process.
[0034]
(4) Carboxyl end group amount (COOH)
The raw material chips were placed in o-cresol and dissolved by heating at 100 ° C. with stirring. After cooling to room temperature, titration was performed with an N / 50 alkaline solution. From the titration, the following formula A = sample titration (ml)
B = Blank titration (ml) (solvent titration)
W = Sample weight (g)
COOH (equivalent / ton) = ((A−B) × 1/50 × 10e ³ ) / W
Was used to calculate the carboxyl end group amount (COOH).
[0035]
(5) One sample having a surface oligomer amount of 40 mm × 40 mm was extracted with 50 mL of chloroform at 25 ° C. for 60 minutes, and the absorbance (ABS250) at 250 nm of the extract was measured with a Hitachi 220S spectrometer. Surface oligomer amount is the following calculation formula surface oligomer amount (mg / m ² ) = ABS250 × 66.469
I asked more.
[0036]
(6) Centerline surface roughness (SRa), number of peaks (SPc)
Using a three-dimensional surface roughness meter (manufactured by Kosaka Laboratory, ET-30HK), measurement was performed by the stylus method under the following conditions.
Needle diameter 2 (μmR)
Needle pressure 10 (mg)
Measurement length 500 (μm)
Vertical magnification 20000 (times)
CUT OFF 250 (μm)
Measurement speed 100 (μm / s)
Measurement interval 5 (μm)
Number of records 80 lines Hysteresis width ± 6.25 (nm)
Reference area 0.1 (mm ² ).
[0037]
(7) Wetting tension According to the method described in JIS-K-6768-1995, the wetting tension of the film surface was measured.
[0038]
(8) Gas barrier properties 48 hours after vapor transmission rate vapor deposition, it was measured under the condition of 90 RH% at 40 ° C. according to the method B described in JIS-K-7129-1992 using a water vapor transmission rate meter PERMATRAN-W1A manufactured by Modern Control. The water vapor permeability measured was evaluated as follows.
A: 0 (g / m ² · day) or more, less than 2 (g / m ² · day) ○: 2 (g / m ² · day) or more, less than 4 (g / m ² · day) ×: 4 ( g / m ² · day) or more.
[0039]
B. After 48 hours of oxygen permeability deposition, oxygen permeation was performed under the conditions of 20 ° C. and 0% RH according to the method B described in JIS-K-7126-1987 using an oxygen permeability measuring device OX-TRAN100 manufactured by Modern Control. The rate was measured. The measured oxygen permeability was evaluated as follows.
: 0 (cc / m ² · day) or more, less than 2 (cc / m ² · day) ○: 2 (cc / m ² · day) or more, less than 4 (cc / m ² · day) ×: 4 ( cc / m ² · day) or more.
[0040]
(9) Deposited film adhesion (laminate strength)
An adhesive prepared by mixing Adcoat 503 (AD503) manufactured by Toyo Morton Co., Ltd., curing agent CAT-10 and ethyl acetate at a ratio of 100: 5: 100 WT% was applied to the vapor deposition surface of the sample with a # 12 Maying bar. After coating, the film was dried in a hot air oven at 70 ° C. for 30 seconds, and then bonded to a corona-treated surface of polypropylene film and Toray Fan ZK62 (60 μm) manufactured by Toray, and aged at 40 ° C. for 72 hours using a hot air oven. The bonded sample was cut to a width of 15 mm, and the polypropylene film and the polyester film were peeled off at a peeling angle of 90 ° with a Tensilon (tensile tester), and the stress at that time was measured. The laminate strength after the boil treatment was measured after treating a bonded sample of 200 mm × 200 mm in 95 ° C. water for 30 minutes. The measured value was evaluated as follows.
A: 600 g / 15 mm width or more ○: 500 g / 15 mm width or more, less than 600 g / 15 mm width ×: less than 500 g / 15 mm width
[0041]
(10) Workability Evaporation and handling of the film at the time of processing (wrinkle, fluttering, slipping property, etc.) were judged by ○ ×. If it is good and no problem, it is ○.
[0042]
【Example】
Next, the present invention will be described based on examples, but is not necessarily limited thereto.
[0043]
Example 1
After vacuum-drying polyethylene terephthalate pellets (ultraviscosity 0.63 dl / g) having a carboxyl end group amount of 40 equivalents / ton containing 0.06% by weight of silicon dioxide particles having an average particle diameter of about 1.5 μm to a moisture content of 20 ppm, It is supplied to an extruder, melt extruded at 280 ° C., filtered through a 10 μm cut filter, extruded from a T-shaped die into a sheet, and cooled and solidified on a cooling drum having a surface temperature of 25 ° C. by an electrostatic adhesion method. It was. The unstretched PET film thus obtained was heated to 115 ° C. and then stretched 1.2 times in the longitudinal direction, and further 1.48 times at 125 ° C. and then 2.62 times at 113 ° C. A uniaxially stretched film was drawn. This uniaxially stretched film was preheated at 100 ° C. and then stretched 3.9 times in the width direction while being heated to 105 ° C. This film is introduced into hot air at 233 ° C., fixed with tension and heat for 3 seconds, and then cooled by 5% relaxation of the original film width in the width direction within the same atmospheric temperature. After finally cooling to room temperature, a corona discharge treatment was performed at a treatment strength of 20 W · min / m ² , and this was guided to a winder and wound up to obtain a mill roll. Aluminum oxide was deposited on the 12 μm film thus obtained. In the method of depositing aluminum oxide on the surface of the biaxially oriented polyester film, the film is set on the unwinding device of a continuous vacuum vapor deposition machine and travels through a cooling metal drum to wind the film. At this time, the pressure of the continuous vacuum evaporator is reduced to 10 ⁻⁴ Torr or less, and the aluminum crucible is charged into the alumina crucible from the lower part of the cooling drum to heat and evaporate the metal aluminum, and oxygen is contained in the vapor. Was deposited and deposited on the film while oxidizing to form an aluminum oxide film having a thickness of 30 nm. The evaluation results are shown in Tables 1 and 2.
[0045]
Example 2
Contains 0.15% by weight of precipitated particles having an average particle size of 1.0 μm (particles precipitated during the polymerization process) and 0.1% by weight of silicon dioxide particles having a particle size of about 1.5 μm, and contains 50 equivalents of carboxyl end groups. / Ton polyethylene terephthalate was used as a raw material. Further, the stretching in the longitudinal direction was changed to 1.2 times at 110 ° C and then to 2.8 times at 120 ° C, and the tension heat fixation temperature was changed to 228 ° C.
[0048]
Example 3
The main layer is polyethylene terephthalate pellets containing 0.05% by weight of silicon dioxide particles having an average particle size of about 0.2 μm, and the secondary layer is polyethylene terephthalate pellets containing 0.10% by weight of silicon dioxide particles having an average particle size of about 1.5 μm. A main layer / sublayer was laminated at a lamination ratio of 8/1 immediately before the die, and a transparent vapor-deposited polyester film was obtained by performing main layer-side corona discharge treatment and vapor deposition according to Example 1.
[0049]
Comparative Example 1
The amount of carboxyl end groups in Example 1 was changed to 23 equivalents / ton, the longitudinal stretching was changed to 1.2 times at 124 ° C., then to 2.8 times stretched at 111 ° C., and the tension heat setting temperature was changed to 238 ° C.
[0050]
Comparative Example 2
Polyethylene terephthalate containing 0.15% by weight of silicon dioxide particles having an average particle diameter of about 0.2 μm and a carboxyl end group content of 65 equivalents / ton was used as a raw material. Moreover, the width direction draw ratio of Example 1 was changed to 4.5 times, and the tension heat fixation temperature was changed to 200 ° C.
[0051]
Comparative Example 3
The intrinsic viscosity of the raw material of Example 1 was changed to 0.55 dl / g, the carboxyl end group amount was changed to 45 equivalents / ton, the longitudinal stretching was changed to 3.5 times at 120 ° C., and the tension heat fixation temperature was changed to 238 ° C. did.
[0052]
Comparative Example 4
The tension heat fixing temperature was changed to 223 ° C. to a resin containing 0.20% by weight of silicon dioxide particles having an average particle size of about 1.5 μm as the polyester resin raw material of Example 1.
[0053]
Comparative Example 5
The amount of carboxyl end groups of the polyester resin of Example 3 was changed to 40 equivalents / ton.
[0054]
Comparative Example 6
The corona discharge treatment of Example 1 was changed to none.
[0055]
[Table 1]

[0056]
[Table 2]

[0057]
【Effect of the invention】
The transparent vapor-deposited polyester film obtained by the present invention is characterized in that a high gas barrier performance can be stably imparted with a thin vapor-deposit film thickness, the adhesion of the vapor-deposited film is good, and high productivity can be obtained.
[0058]
The transparent vapor-deposited polyester film obtained by the present invention can be used alone, but further, printing, coating a protective layer or the like on the vapor-deposited film, laminating a heat seal layer, It can be further processed and used, for example, by laminating with a film or by combining them. Moreover, a heat seal layer can be laminated on the non-deposited surface, laminated with another film, or a combination thereof.

Claims (4)

A biaxially oriented polyethylene terephthalate film for transparent vapor deposition characterized by satisfying the following formulas (1) to ( 8 ) and containing silicon dioxide particles.
0.160 ≦ fn ≦ 0.180 (1)
1.495 ≦ nZD ≦ 1.505 (2)
250 MPa ≤ Y150 (3)
215 ° C ≦ Tmeta ≦ 231 ℃ (4)
25 equivalents / ton ≦ COOH ≦ 60 equivalents / ton (5)
Tmeta ≧ 245−0.5 × COOH (6)
5nm ≤ SRa ≤ 80nm (7)
10 / 0.1mm ² ≤ SPc ≤ 130 / 0.1mm ² (8)
fn: plane orientation coefficient nZD: thickness-direction refractive index Y150: longitudinal Young's modulus under an atmosphere of 150 ° C. Tmeta: film melting sub-peak COOH: film carboxyl end group amount
SRa: Centerline surface roughness
SPc: Number of mountains The biaxially oriented polyethylene terephthalate film for transparent vapor deposition according to claim 1, wherein at least one surface has a wetting tension of 50 mN / m or more. The biaxially oriented polyethylene terephthalate film for transparent vapor deposition according to claim 1 or 2, wherein the amount of oligomer on the film surface is 60 mg / m ² or less. Transparent deposited polyethylene terephthalate film, characterized by comprising providing at least a transparent vapor deposition layer on one surface of a polyethylene terephthalate film according to any one of claims 1-3.