JP4164899B2 - Vapor deposited biaxially oriented polyester film - Google Patents

Description

【００５４】
【発明の効果】
本発明の蒸着２軸配向ポリエステルフイルムにおいては、以上のような構成としたため、薄い蒸着膜厚さでありながら高いガスバリア性能及び防湿性能を安定して付与できるという効果が得られる。
【００５５】
また、本発明の蒸着２軸配向ポリエステルフイルムは、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 vapor-deposited biaxially oriented polyester film, and particularly to a vapor-deposited biaxially oriented polyester film having excellent gas barrier performance and moisture-proof performance while being a thin vapor-deposited film.
[0002]
[Prior art]
Conventionally, biaxially oriented polyester films having excellent transparency and mechanical properties have been widely used for packaging materials and the like. Furthermore, a biaxially oriented polyester film coated with polyvinylidene chloride is widely known for the purpose of improving the moisture resistance of the film. However, polyvinylidene chloride needs to be thickened to improve moisture resistance, and productivity is poor. In addition, polyvinylidene chloride generates chlorine-based gas at the time of incineration, and it has been pointed out that the incinerator is corroded and adversely affects the global environment. Further, it is said that the burden on the incinerator for purifying exhaust gas is also large. . As a packaging film for solving these problems, it has been well known that a metal film such as aluminum or a metal oxide formed on the surface of a polyester film is excellent in gas barrier properties and moisture resistance. Of these, a silicon oxide film formed on a polymer resin film is disclosed in Japanese Patent Publication No. 53-12953, and an aluminum oxide film formed on a polymer resin film is disclosed in Japanese Patent Publication No. 62-179935. Are known.
[0003]
However, such a conventional film having excellent gas barrier properties and moisture resistance has the following problems. Metallic aluminum requires a thick film thickness to ensure high gas barrier properties and moisture resistance, but this reduces productivity. Further, since the film becomes opaque by vapor deposition, there is a problem that the contents cannot be seen when used for packaging.
[0004]
The silicon oxide film is also required to be thick in order to ensure high gas barrier properties and moisture resistance. However, when the film thickness is increased, curling is liable to occur, handling properties are deteriorated, and when the film is handled violently, there is a problem in that the vapor-deposited film is cracked and gas barrier properties and moisture resistance are lowered. There is also a problem that the silicon oxide film is colored.
[0005]
In addition, the aluminum oxide film is thinner than the silicon oxide film, and can exhibit a certain degree of gas barrier properties and moisture proof properties. There was a problem that moisture resistance could not be expressed. Further, if the film thickness is increased in order to develop the barrier property, there arises a problem that the aluminum oxide film is colored.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a vapor-deposited biaxially oriented polyester film having an excellent gas barrier property and moisture-proof property at the same time while being a thin vapor-deposited layer in order to solve the above-described problems.
[0007]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that gas barrier properties and moisture resistance depend on the surface structure of the biaxially oriented polyester film before vapor deposition, and have reached the present invention.
[0008]
That is, the vapor-deposited biaxially oriented polyester film according to the present invention has at least one side,
0.1 nm ≦ SRa ≦ 80 nm
2 pieces / 0.1 mm ² ≦ SPc ≦ 150 pieces / 0.1 mm ²
0.23 nm / piece ≦ SRa / SPc ≦ 0.39 nm / piece
(SRa: center plane average roughness, SPc: number of peaks)
A biaxially oriented polyester film satisfying the above requirements is characterized in that a vapor deposition layer having a thickness of 5 to 150 nm is provided on the surface.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail together with preferred embodiments.
The biaxially oriented polyester film in the present invention is produced by stretching an unstretched polyester sheet or film in a so-called biaxial direction in the longitudinal direction and the width direction, and biaxially oriented by wide-angle X-ray diffraction. The one showing the pattern. In particular, simultaneous biaxial stretching in which stretching in the longitudinal direction and width direction is simultaneously performed is preferable compared to sequential biaxial stretching, in which defects due to scratches are less likely to occur on the film surface.
[0010]
The polyester resin constituting the biaxially oriented polyester film used in the present invention includes, as an acid component, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, adipic acid, azelaic acid, sebacin Aliphatic dicarboxylic acids such as acid and decanedicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid can be used. As alcohol components, aliphatic diols such as ethylene glycol, diethylene glycol, butanediol and hexanediol, cyclohexanedi An alicyclic diol such as methanol can be used.
[0011]
In addition, known additives in this polyester resin, for example, heat stabilizer, oxidation stabilizer, weather stabilizer, UV absorber, organic lubricant, pigment, dye, filler, antistatic agent, core You may mix | blend an agent etc. suitably.
[0012]
The intrinsic viscosity (measured in orthochlorophenol at 25 ° C.) of the polyester resin as described above is preferably in the range of 0.4 to 1.2 dl / g, more preferably 0.5 to 0. .8 dl / g, more preferably 0.55 to 0.75 dl / g.
[0013]
In the present invention, particles may be contained in the biaxially oriented polyester film, and the contained particles include particles produced during polymerization with various nucleating agents, silicon dioxide particles, calcium carbonate particles, alumina particles, titanium oxide particles. Typical examples thereof include inorganic particles such as barium sulfate particles, organic particles such as crosslinked polystyrene particles, acrylic particles and imide particles, or a mixture thereof. The diameters of the various particles used are not particularly limited, but an average particle diameter measured by a sedimentation method or a light scattering method is usually 0.05 to 8 μm, preferably 0.1 to 4 μm.
[0014]
As the biaxially oriented polyester film in the present invention, a biaxially oriented polyester film made of a resin having a —COOH amount (carboxyl terminal group amount) of 25 to 55 equivalent / t is suitable. When the amount of —COOH of the resin is less than 25 equivalent / t, the gas barrier property and moisture resistance of the vapor-deposited biaxially oriented polyester film cannot be sufficiently exhibited. When the amount of the resin -COOH exceeds 55 equivalent / t, the appearance of the vapor-deposited biaxially oriented polyester film is colored, or in the case of the transparent vapor-deposited biaxially oriented polyester film, the transparency is deteriorated. There are problems such as deterioration of film properties.
[0015]
The surface on the vapor deposition surface side of the biaxially oriented polyester film used in the present invention has a wetting tension of 45 mN / m or more, preferably 48 mN / m or more, more preferably 50 mN / m or more. If the wetting tension is less than 45 mN / m, the gas barrier property and moisture resistance of the vapor-deposited biaxially oriented polyester film cannot be sufficiently exhibited, or the adhesion between the vapor-deposited layer and the biaxially-oriented polyester film is insufficient. When post-processing such as laminating on the vapor-deposited layer of oriented polyester film, problems such as peeling of the vapor-deposited layer and biaxially oriented polyester film are likely to occur. As a method for controlling the wetting tension within the above range, typically, corona discharge treatment can be used. As a result of examination by the inventors, it has been found that the gas barrier property and moisture resistance of the biaxially oriented polyester film after vapor deposition are deteriorated when the corona discharge treatment is not performed.
[0016]
The wetting tension of the non-deposition surface of the biaxially oriented polyester film used in the present invention is preferably 40 mN / m or more. If the wetting tension is less than 40 mN / m, there is a problem in the post-processing printability and laminate strength of the non-deposition surface of the vapor-deposited biaxially oriented polyester film.
[0017]
Although the thickness of the biaxially oriented polyester film used for this invention is not specifically limited, Usually, 0.5-500 micrometers, Preferably it is 1-300 micrometers, More preferably, it is 3-25 micrometers.
[0018]
SRa on the vapor deposition surface side surface of the biaxially oriented polyester film used in the present invention needs to be 0.1 nm or more and 80 nm or less. If SRa is less than 0.1 nm, slipping may be poor and the film may not be wound into a roll. On the other hand, if SRa exceeds 80 nm, gas barrier properties and moisture resistance after deposition are deteriorated. 1 nm to 60 nm is preferable, and 10 nm to 50 nm is more preferable. Here, SRa is a parameter of the three-dimensional surface roughness and is defined as the center plane average roughness.
[0019]
The SPc on the vapor deposition surface side surface of the biaxially oriented polyester film used in the present invention needs to be ^{2 /} 0.1 mm ² or more and 150 / 0.1 mm ² or less. That is, if SPc is less than 2 0.1 mM ^2, and because there are problems such slippage can not be wound film worse into a roll, the SPc is 150 0.1 mM ² When exceeding, it is because the gas barrier property and moisture-proof property after vapor deposition will deteriorate. The SPc is preferably 10 pieces / 0.1 mm ² or more and less than 130 pieces / 0.1 mm ² , more preferably 30 pieces / 0.1 mm ² or more and less than 100 pieces / 0.1 mm ² . Here, 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 surface and having a distance of 5 nm from the center plane is provided above and below the center plane, and the number of peaks recognized as peaks on both the top and bottom planes is measured and converted to 0.1 mm ² It is expressed.
[0020]
In the present invention, the value of SRa / SPc needs to be 0.23 nm / piece or more for the vapor deposition surface side surface of the biaxially oriented polyester film. That is, if SRa / SPc is less than 0.23 nm / piece, gas barrier properties and moisture resistance after vapor deposition deteriorate. SRa / SPc is preferably 0.25 nm / piece or more, more preferably 0.27 nm / piece or more. Here, SRa / SPc is a parameter corresponding to the average roughness per mountain.
[0021]
The thickness of the vapor deposition layer provided in the vapor deposition biaxially oriented polyester film of this invention needs to exist in the range of 5-150 nm. If it is thinner than this, the gas barrier property and moisture proof property will deteriorate. If it is thicker than this, productivity decreases. In particular, in the case of a metal oxide, if the film thickness is increased, the film tends to curl and handling is poor, and if it is handled violently, the deposited film will crack, resulting in decreased gas barrier properties and moisture resistance, and the deposited film is colored. To do.
[0022]
A metal or a metal oxide can be used as a vapor deposition layer provided in the vapor deposition biaxially oriented polyester film of the present invention. Typical examples of the metal include aluminum, silver, chromium, tin, and copper. Among them, aluminum is preferable in consideration of food hygiene, cost, and stability of the deposited film. Typical examples of the metal oxide include a silicon oxide film and an aluminum oxide film. Among them, an aluminum oxide film is preferable in consideration of cost, production equipment, and coloring.
[0023]
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.
[0024]
After the amount of -COOH is adjusted in the polymerization stage 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 and melted by a method such as an extruder Then, it is formed into a film (usually on a cooling drum). This film is heated to 75 to 130 ° C. and stretched 2 to 9 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 to 9 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, it is better to perform a 3-12% relaxation treatment in the width direction. The heat-treated film is gradually cooled through an intermediate cooling zone, and when the film reaches room temperature, the film is taken up by a winder. Next, this mill roll is subjected to a slitter to form a product roll. A corona discharge treatment is performed on the surface of the vapor deposition surface of the film while the product roll is rewound. When the corona discharge treatment is performed on the non-deposited surface side, the rewinding is performed.
[0025]
A vapor-deposited layer is provided on the biaxially oriented polyester film thus obtained. As a process for providing a metal vapor deposition film, a vacuum vapor deposition method, a sputtering method, an ion plating method, a chemical vapor deposition method, or the like can be used. From this point, it can be used more preferably. 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 can be employed. As a reactive gas for forming an oxidizing atmosphere, water or a rare gas may be added mainly with oxygen. Further, a method of promoting reaction such as adding ozone or ion assist may be adopted. In these vapor deposition processes, it is more preferable to use a plasma treatment on the surface of the biaxially oriented polyester film because gas barrier properties and moisture permeability are improved.
[0026]
In order to deposit silicon oxide by the reactive deposition method, it is possible to employ a method in which Si metal, SiO or SiO ₂ is evaporated by an electron beam heating method, and silicon oxide is deposited on a biaxially oriented polyester film in an oxidizing atmosphere. The method described above is used as a method of forming the oxidizing atmosphere.
[0027]
[Measurement method of characteristic values]
The characteristic values of the present invention are based on the following measurement methods.
(1) SRa, 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.
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 Hysteresis width: ± 5 (nm)
Reference area: 0.1 (mm ² )
[0028]
(2) Film thickness of vapor deposition layer Using a transmission electron microscope (JEM-1200EX, manufactured by JEOL Ltd.), the cross section was observed with an ultrathin slice method at an acceleration voltage of 100 kV, and the film thickness of the vapor deposition film was measured.
[0029]
(3) Wetting tension According to the method described in JIS-K-6768-1995, the wetting tension of the film surface was measured.
[0030]
(4) -COOH amount Raw material chips were placed in o-cresol and dissolved by heating at 100 ° C while stirring. After cooling to room temperature, titration was performed with an N / 50 alkaline solution. From the titration amount, the amount of —COOH was calculated by the following formula.
A = Sample titration (ml)
B = Blank titration (ml) (solvent titration)
W = Sample weight (g)
-COOH amount (equivalent / t) = ((A-B) × 1/50 × 10 ³ ) / W
[0031]
(5) Gas barrier properties Water vapor permeability 48 hours after vapor deposition, the water vapor permeability of the deposited film was measured according to the method B described in JIS-K-7129-1992. The water vapor permeability measured was evaluated as follows.
○: 0 (g / m ² · day) or more and less than 3 (g / m ² · day) Δ: 3 (g / m ² · day) or more and less than 6 (g / m ² · day) ×: 6 ( g / m ² · day) or more [0032]
B. After 48 hours of vapor deposition of oxygen permeability, the oxygen permeability of the vapor deposition film was measured according to the method B described in JIS-K-7126-1987. The measured oxygen permeability was evaluated as follows.
○: 0 (cc / m ² · day) or more and less than 3 (cc / m ² · day) Δ: 3 (cc / m ² · day) or more and less than 6 (cc / m ² · day) ×: 6 ( cc / m ² · day) or more
(6) Appearance of vapor deposition film The appearance of the vapor deposition film was evaluated as follows.
○: Colorless. It is colorless and transparent in transparent vapor deposition.
Δ: Slightly yellow or slightly white. In transparent vapor deposition, it is slightly opaque and colored.
X: Yellow or white. Opaque and colored in transparent deposition.
[0034]
(7) The wound form of the wound-film-deposited film was evaluated as follows: ○: No defects in appearance when wound in roll form ×: Defects in appearance when wound in roll form
【Example】
Example 1
Polyethylene having a COOH content of 35 equivalents / t, containing 0.15% by weight of precipitated particles having an average particle size of 1 μm (particles precipitated during the polymerization step) and 0.1% by weight of silicon dioxide particles having a particle size of about 1.5 μm After terephthalate (PET) pellets (extreme viscosity 0.63 dl / g) were vacuum dried to a moisture content of 20 ppm, they were supplied to an extruder, melt extruded at 280 ° C., filtered through a 10 μm cut filter, and then a T-shaped base. Then, it was extruded into a sheet shape, and this was cooled and solidified on a cooling drum having a surface temperature of 50 ° C. by an electrostatic adhesion method. The unstretched PET film thus obtained was heated to 95 ° C. and stretched 3.5 times in the longitudinal direction to obtain a uniaxially stretched film. This uniaxially stretched film was preheated at 98 ° 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 225 ° C., and fixed with tension heat for 1 second, and then cooled by applying 8% relaxation of the original film width in the width direction within the same atmospheric temperature. Finally, it was cooled to room temperature, and this was guided to a winder and wound up to form a mill roll. Next, this mill roll was subjected to a slitter to obtain a product roll having a predetermined width. While rewinding the product roll, each film both surfaces subjected to corona discharge treatment in the processing intensity of 20W · min / m ^2. 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 characteristics of this deposited biaxially oriented polyester film are shown in Table 1.
[0036]
Example 2
The raw material PET pellets of Example 1 were changed to -COOH amount 44 equivalent / t, silicon dioxide particles having a particle size of about 1.5 µm to 0.08 wt%, and corona discharge treatment strength to 14 W · min / m ² .
[0037]
Example 3
The silicon dioxide particles of Example 1 were changed to 0.05% by weight with a particle size of about 1.5 μm and 0.05% by weight with a particle size of about 0.8 μm.
[0038]
Example 4
The raw material PET pellets of Example 1 were changed to -COOH amount 30 equivalent / t.
[0040]
Example 5
The raw material PET pellets of Example 1 were changed to -COOH amount 33 equivalent / t, silicon dioxide particles having a particle diameter of about 1.5 μm, 0.07 wt%, and the thickness of the aluminum oxide film was changed to 20 nm.
[0041]
Example 6
The raw material PET pellets of Example 1 were changed to 0.07 wt% of silicon dioxide particles having a —COOH amount of 33 equivalent / t, a particle size of about 1.5 μm, and the thickness of the aluminum oxide film to 110 nm.
[0042]
Example 7
The biaxial stretching method of Example 1 was changed to a method in which an unstretched PET film was heated to about 80 ° C. to 120 ° C. and simultaneously stretched 3 times in the longitudinal direction and 3 times in the width direction.
[0043]
Example 8
The raw material PET pellets of Example 1 were changed to a -COOH amount of 58 equivalents / t.
[0044]
Comparative Example 1
The raw material PET pellets of Example 1 were changed to 0.11% by weight of silicon dioxide particles having a —COOH amount of 37 equivalent / t and a particle size of about 2.5 μm.
[0045]
Comparative Example 2
The raw material PET of Example 1 was changed to one without precipitated particles (particles precipitated during the polymerization process) and silicon dioxide particles.
[0046]
Comparative Example 3
The particle diameter of the silicon dioxide particles of Example 1 was changed to about 0.8 μm and the amount was changed to 0.20% by weight.
[0047]
Comparative Example 4
The particle size of the silicon dioxide particles of Example 1 was changed to about 0.8 μm and the amount was changed to 0.15 wt%.
[0048]
Comparative Example 5
The thickness of the aluminum oxide film of Example 1 was changed to 200 nm.
[0049]
Comparative Example 6
The thickness of the aluminum oxide film of Example 1 was changed to 20 nm.
[0050]
Comparative Example 7
The raw material PET pellets of Example 1 were changed to -COOH amount 20 equivalent / t.
[0051]
Comparative Example 8
The raw material PET pellets of Example 1 were changed to -COOH amount 80 equivalent / t.
[0052]
Comparative Example 9
It changed into not performing the corona discharge process of Example 1. FIG.
[0053]
[Table 1]

[0054]
【The invention's effect】
Since the vapor-deposited biaxially oriented polyester film of the present invention has the above-described configuration, it is possible to stably provide high gas barrier performance and moisture-proof performance while having a thin vapor deposition film thickness.
[0055]
Further, the vapor-deposited biaxially oriented polyester film of the present invention can be used alone, but further, printing, coating a protective layer, etc. on the vapor-deposited film, laminating a heat seal layer, etc. It can also be used by further processing, such as laminating with these films, or combining them. Moreover, a heat seal layer can be laminated on the non-deposited surface, laminated with another film, or a combination thereof.

Claims (7)

At least one side
0.1 nm ≦ SRa ≦ 80 nm
2 pieces / 0.1 mm ² ≦ SPc ≦ 150 pieces / 0.1 mm ²
0.23 nm / piece ≦ SRa / SPc ≦ 0.39 nm / piece
(SRa: center plane average roughness, SPc: number of peaks)
A biaxially oriented polyester film having a thickness of 5 to 150 nm provided on the surface of a biaxially oriented polyester film satisfying the above. The vapor-deposited biaxially oriented polyester film according to claim 1, wherein the coating tension on at least one side is 45 mN / m or more. The vapor-deposited biaxially oriented polyester film according to claim 1 or 2, wherein at least one surface is subjected to corona discharge treatment. The vapor-deposited biaxially stretched polyester film according to any one of claims 1 to 3, wherein the vapor-deposited layer is a transparent vapor-deposited layer. The vapor-deposited biaxially oriented polyester film according to claim 4, wherein the transparent vapor-deposited layer is made of aluminum oxide or silicon oxide. The vapor-deposited biaxially oriented polyester film according to any one of claims 1 to 5, wherein the amount of -COOH of the biaxially oriented polyester film is 25 to 55 equivalent / t. The vapor-deposited biaxially oriented polyester film according to any one of claims 1 to 6, wherein the biaxially oriented polyester film is simultaneously biaxially stretched.