JPH09156021A - Metallic oxide deposited non-oriented film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve gas barrier properties and secondary processability by setting the light transmittance and water vapor transmittance of a metallic oxide deposited film at specified values. SOLUTION: A metallic oxide deposited film is formed by depositing a metallic oxide on a non-oriented film having the film density of 0.9g/cm<3> or more and crystal melting calorie of 75J/g or more, and the light transmittance of the metallic oxide deposited film is set to be 69-90% or less and the water vapor transmittance is set to be 2.5g/m<2> or less. As the metallic oxide, incomplete oxidized aluminum is preferred from the viewpoint of the bonding properties, gas barrier properties and processability with the film, and its thickness is preferably set to be 5-50nm. Oxygen gas is fed to evaporate fiber sites while heat depositing aluminum metal in a vacuum deposition device, and aluminum is cohesion deposited on a traveling film face while oxidizing aluminum to form and attach a deposited layer by a means for changing the light transmittance. The ratio between the avaporated amount of aluminum and the feed amount of oxygen gas at that time is changed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a metal oxide vapor-deposited unstretched film. More specifically, the present invention relates to a metal oxide vapor-deposited non-stretched film which is transparent and has excellent gas barrier properties and is excellent in secondary processability by subjecting a non-stretched film to vapor deposition of a metal oxide.

[0002]

2. Description of the Related Art Conventionally, polyester-based and polyolefin-based unstretched films are generally used by being laminated with other substrates because they are excellent in film forming property, transparency, moldability and heat sealing. Among them, unstretched polypropylene film is excellent in transparency, moisture resistance and heat sealability, laminated with a heat resistant base material such as biaxially oriented polypropylene film or polyethylene terephthalate film, and widely used as a heat seal layer of packaging material for packaging applications, etc. Is used for. Further, in order to improve the gas barrier property of the film, it is widely used as a gas barrier film coated with vinylidene chloride. However, vinylidene chloride has been pointed out to have an adverse effect on the environment because chlorine-based gas is generated during waste incineration, and it is said that the burden on the incinerator for purifying exhaust gas is large. Therefore, as a packaging film for solving this environmental problem, a structure of a heat-resistant film / printing layer / adhesive layer / vapor-deposited film / heat-resistant film / adhesive layer / unstretched polypropylene film provided with a metal vapor-deposited film is mainly used. . In recent years, there has been a strong demand for simplification of the film structure and cost reduction. Further, a vapor deposition film is required to have transparency, and a vapor deposition film which can be used in a microwave oven is desired. Therefore, for the purpose of simplifying the structure and reducing the cost, a structure in which a heat-resistant film is omitted by subjecting an unstretched polypropylene film to metal vapor deposition has been studied. However, since the unstretched polypropylene film has a low Young's modulus, it has a low tensile strength during vapor deposition and cracks in the vapor deposition layer, and also has a problem that the gas barrier performance as a packaging bag is insufficient due to poor bag-making processability. there were. Further, as a transparent gas barrier film, those in which silicon oxide or aluminum oxide is formed on the film are known from JP-B-53-12953 and JP-A-62-179935. However, these techniques have not been able to impart a high gas barrier property to unstretched polypropylene films.

[0003]

SUMMARY OF THE INVENTION The present invention has a transparent and high gas barrier property obtained by subjecting an unstretched film to vapor deposition of a metal oxide, which cannot be achieved by such a technique. It is intended to provide a metal oxide vapor-deposited unstretched film which is excellent in processing and laminating.

[0004]

In order to solve the above problems, a metal oxide is vapor-deposited on an unstretched film having a film density of 0.9 g / cm ³ or more and a crystal fusion heat amount of 75 J / g or more. The metal oxide vapor-deposited film has a light transmittance of 60 to 90% and a water vapor transmission rate of 2.5 g / m ² · d or less. The film.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The unstretched film of the present invention is an unstretched film of a thermoplastic resin, and a polyester film and a polyolefin film are preferable in terms of transparency and moldability, and a polypropylene-based film is particularly preferable. The combined film is preferable in terms of moisture resistance and heat sealability. Among them, polypropylene random copolymer (hereinafter abbreviated as r-CPP), a copolymer of propylene and α-olefin having a substantially isotactic structure is excellent in adhesion to the metal vapor deposition layer and has gas barrier property. It is preferable because it becomes high. Examples of the α-olefin monomer to be copolymerized include ethylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1 and the like, with ethylene and butene-1 being particularly preferred. The copolymerization amount of the α-olefin monomer is preferably in the range of 3 to 15% by weight because the heat of fusion of crystal is 75 J / g or more, and in the case of the ethylene monomer, 2 to 6% by weight, butene-
In the case of one monomer, the range of 3 to 10% by weight is preferable.
Specific implementation measures include ethylene-propylene copolymer (hereinafter abbreviated as EPC), ethylene-propylene-butene-1 copolymer (hereinafter abbreviated as EPBC), propylene-butene-1 copolymer (hereinafter abbreviated). BPC) and the like. Since the non-stretched polypropylene film uses the non-deposited surface as a heat seal layer during bag making, the melting point of r-CPP is preferably 125 to 145 ° C. from the viewpoint of heat seal strength. Also r-CPP
Has a melt flow index (MFI) of 1-15 g /
The range of 10 minutes is preferable because the extrusion film-forming property is good, and more preferably 2 to 10 g / 10 minutes.

Next, the density of the film of the present invention is 0.9 g /
It must be at least cm ³ . Density 0.9g /
If it is less than cm ³ , the water vapor transmission rate after vapor deposition is 2.5 g / m 2.
Not only is it unfavorable because it becomes larger than ² · d, but the Young's modulus of the film is low, so wrinkles may form during slitting and lamination, or the film may stretch and crack in the vapor deposition layer, resulting in poor gas barrier properties. Further, the secondary workability is also deteriorated, which is not preferable.

As a method for increasing the film density, the polypropylene polymer is fed to an extruder, melt-extruded into a sheet, wound around a metal drum, and cooled and solidified.
When the unstretched polypropylene film is used, the crystallinity of the film is increased by raising the temperature of the metal drum to a high temperature of 50 ° C. or more, and the film density is 0.9 g / cm ^3.
That is all. As another method, a high-density polyethylene (hereinafter abbreviated as HDPE) having a density of 0.93 or more is used.
By adding ˜15% by weight, HDPE becomes a crystal nucleating agent for a polymer containing polypropylene as a main component, and the density of the film becomes higher than the addition ratio. At this time, HDPE
If the amount added is less than 1% by weight, the film density does not increase and the Young's modulus of the film is low, so wrinkles may form during slitting or lamination, or the film may extend and crack in the vapor deposition layer, resulting in gas barrier properties. Is not preferable, and the secondary processability is also deteriorated. If it exceeds 15% by weight, the film is whitened, the light transmittance is lowered, and the heat seal strength during bag making is not preferable. As another method of increasing the film density, there is a method of increasing the film density by adding a known crystal nucleating agent,
The organic crystal nucleating agent is not preferable because it bleeds out on the film surface to deteriorate the adhesion of metal vapor deposition and deteriorates the water vapor transmission rate.

Further, the film of the present invention contains inorganic particles and / or
Or by adding any of the crosslinked organic particles,
It is preferable because the effect of the crystal nucleating agent and the effect of the lubricant are exhibited. The particle shape at this time is preferably spherical, and the particle diameter is preferably 1 to 6 μm. The addition amount is 0.05 to 0.5 part by weight, preferably 0.1 to 0.3 part by weight. When the amount added is less than 0.05 parts by weight, when the vapor-deposited film is rewound, slippage with the non-vapor-deposited surface is poor and blocking occurs, cracks occur in the vapor-deposition layer, and the gas barrier property deteriorates, which is not preferable. Is more than 0.5 parts by weight, the surface of the film is too rough and the transparency and heat sealability are deteriorated. Further, the adhesion of the vapor deposition layer is deteriorated and the gas barrier property is deteriorated, which is not preferable.

The Young's modulus in at least one direction of the film of the present invention is preferably 0.7 GPa or more, and particularly, the Young's modulus in the longitudinal direction of the film is preferably 0.7 GPa or more. If the Young's modulus is less than 0.7 GPa, the tensile strength at the time of vapor deposition processing or laminating processing is inferior, so cracks occur in the vapor deposition layer and the gas barrier property deteriorates, which is not preferable.

The film of the present invention preferably contains a small amount of a heat stabilizer, an antioxidant and the like, if necessary. For example, as the heat stabilizer, 2,6-di-tert-butyl-4-methylphenol (BHT) or the like is 0.5 wt% or less, and as the antioxidant, tetrakis- (methylene-).
(3,5-di-tert-butyl-4-hydroxy-4-hydrocinnamate)) butane ("Irganox" 1
010) and the like are preferably added in an amount of 0.1% by weight or less.

Next, the heat of fusion of crystals of the film of the present invention must be 75 J / g or more, and preferably,
It is 80 J / g or more. If the heat of fusion of crystal is less than 75 J / g, the tensile strength during vapor deposition or laminating is poor,
It is not preferable because cracks occur in the vapor deposition layer and the gas barrier property deteriorates.

Further, by subjecting the surface of the unstretched film of the present invention to be vapor-deposited to corona discharge treatment to raise the wetting tension of the film surface to 35 mN / m or more, the adhesion of the vapor-deposited film is improved, which is preferable. . The atmosphere gas at the time of the corona discharge treatment at this time may be any of air, carbon dioxide gas or a mixed system of nitrogen / carbon dioxide gas, particularly a mixed gas of nitrogen / carbon dioxide gas (volume ratio = 95/5 to 50/50). When the corona treatment is applied in the film, the wetting tension of the film surface becomes 35
It is preferable because it can be increased to mN / m or more.

The metal oxide deposited on the unstretched film of the present invention is a film of a metal oxide such as aluminum, zinc, magnesium or silicon. Among them, incomplete aluminum oxide is preferable in terms of adhesion to the film, gas barrier property, and workability. Here, the incomplete aluminum oxide vapor deposition layer is composed of a small amount of aluminum metal (Al) and complete aluminum oxide (Al ₂ O ₃ ) as the metal species constituting the vapor deposition layer. The means for changing the light transmittance is, in a vacuum vapor deposition device equipped with a film traveling device, while heating and evaporating aluminum metal, supplying oxygen gas to the vaporized vapor portion and oxidizing aluminum to agglomerate and deposit on the traveling film surface. Then, a vapor deposition layer is attached. At this time, the light transmittance of the incomplete aluminum oxide vapor deposition film can be changed by changing the ratio of the evaporation amount of aluminum and the supplied oxygen gas amount. At this time, the thickness of the incomplete aluminum oxide vapor deposition layer is preferably 5 to 50 nm, more preferably 10 to 30 nm.

The light transmittance of the metal oxide vapor-deposited unstretched film of the present invention is preferably in the range of 60 to 90%. The film obtained by depositing the complete metal oxide of the vapor deposition layer has a light transmittance of 9
If it exceeds 0%, a transparent film will be obtained, but this is not preferred because the water vapor permeability becomes large. The light transmittance is 60%
If it is less than 1, the transparency is poor and the confirmation of the content is poor when used as a packaging bag, which is not preferable.

The water vapor transmission rate of the film of the present invention is preferably 2.5 g / m ² · d or less, and when the water vapor transmission rate exceeds 2.5 g / m ² · d, contents requiring moisture resistance, For example, when it is used as a packaging bag for potato chips or the like, the long-term storability of the contents is deteriorated, which is not preferable.

The metal oxide vapor-deposited unstretched film of the present invention is used as a packaging material by laminating it with another substrate through an adhesive or an adhesive resin.

Next, the method for producing the film of the present invention will be described.

First, a mixed resin of r-CPP, HDPE and a lubricant is supplied to a vent type twin-screw extruder, melt-mixed at a temperature of 260 ° C., passed through a filtration filter, and then formed into a sheet with a slit-shaped die. The sheet is wound around a metal drum kept at 50 to 90 ° C., cooled and solidified, and wound into a roll as an unstretched polypropylene film. The unstretched polypropylene film is used in an atmosphere of 30 ° C. or higher.
It is preferable that the film is left to stand for a time or more to crystallize. The unstretched polypropylene film thus obtained is subjected to corona discharge treatment or plasma treatment in a dilute gas under reduced pressure in order to increase the wetting tension of the surface on which vapor deposition is performed. Here, the plasma treatment is performed by introducing a small amount of oxygen, argon, helium, carbon dioxide gas or the like into a container having a vacuum degree of 133 Pa or less, and performing glow discharge from the electrode to which a high voltage is applied toward the film surface. Treatment intensity is voltage x current x electrode width / film running speed (W.min /
m ² ) but the treatment strength is preferably 3
~ 200 W · min / m ² , more preferably 5 to 50 W
・ It is min / m ² . Processing strength is 200 W · min /
If it exceeds m ² , sufficient gas barrier performance may not be obtained. The preferred combination when the surface is subjected to a surface treatment and the metal oxide is vapor-deposited on the surface is not particularly limited, but in the case of a metal oxide such as incomplete aluminum oxide or incomplete silicon oxide, in air or nitrogen. It is preferable to carry out at least one of corona discharge treatment and plasma treatment in a mixed gas atmosphere of carbon dioxide gas. Next, the unstretched polypropylene film is set in a vacuum vapor deposition device equipped with a film running device, and run through a cooling metal drum. At this time, while heating and evaporating the aluminum metal, oxygen gas is supplied to the evaporating vapor portion, and while aluminum is oxidized, the aluminum metal is aggregated and deposited on the running film surface, and a vapor deposition layer is attached and wound.
At this time, the light transmittance of the incomplete aluminum oxide vapor deposition film can be changed by changing the ratio of the evaporation amount of aluminum and the supplied oxygen gas amount. After vapor deposition, it is preferable to return the inside of the vacuum vapor deposition apparatus to normal pressure, slit the wound film, and aged at a temperature of 30 ° C. or more for 1 day or more because the gas barrier property is stable.

[0019]

[Method of measuring characteristic values] The characteristic values of the present invention are determined by the following measuring methods.

(1) Isotactic Index (II) A sample is vacuum dried at 130 ° C. for 2 hours. From now on weight W
Take (mg) sample, place in Soxhlet extractor and extract with boiling n-heptane for 12 hours. Next, the sample is taken out, sufficiently washed with acetone, dried at 130 ° C. for 6 hours, and thereafter, the weight W ′ (mg) is measured and obtained by the following equation.

II = (W '/ W) × 100 (%)

(2) Wetting tension of the film surface It was measured by the method of JIS K-6768.

(3) Melt flow index (MF
I) Polypropylene test method according to JIS K-6758 (23
0 ° C, 2.16 kgf).

(4) Water vapor transmission rate (moisture-proof property) It is a value measured at 40 ° C. and 90% RH in accordance with JIS Z-0208, and is shown in units of g / m ² · d.

(5) Thickness of vapor-deposited layer of metal oxide The cross section of the film was photographed with a transmission electron microscope (TEM) under the following conditions to measure the laminated thickness.

Device: JEM-12OOEX manufactured by JEOL Ltd. Observation magnification: 400,000 times Accelerated electron: 100 kV

(6) Light transmittance The metal oxide vapor-deposited unstretched film was measured for transmittance at a wavelength of 550 nm using a spectrophotometer model 324 manufactured by Hitachi Ltd.

(7) Film Density Measured according to JIS K-6758 polypropylene test method.

(8) Heat of fusion of crystals Thermal analyzer S11 manufactured by Seiko Instrument Co.
It was determined from the area of the melting endothermic peak accompanying the melting of crystals when 5 mg of the sample was heated from room temperature at a heating rate of 20 ° C./min using a mold. This area is the area from the baseline to the endothermic side when the temperature rises, and the area until it returns to the baseline position when the temperature is further raised,
Connect the melting start temperature position to the end temperature position with a straight line,
This area was calculated by computer processing.

(9) Young's modulus The sample is attached to a tensile tester (manufactured by Toyo Sokki Co., Ltd.) with a gripping interval of 50 mm in accordance with JIS-K-7127. Then pulling speed 20mm / min, chart speed 500mm
The strength-elongation curve was recorded on a chart paper under the conditions, and the strength-elongation curve was obtained from the slope obtained by drawing a tangent to the rising curve from the base point.

(10) Sliding property According to ASTM D-1894, both sides of the film were superposed and the coefficient of friction was measured. At this time, when the value of μs (coefficient of static friction) is less than 1.0, the slip property is good, and the result is ○.
When the slipperiness was 1.5 or more, it was evaluated as ×, and the middle thereof was evaluated as Δ.

(11) Blocking property A sample having a width of 3 cm and a length of 10 cm was superposed on both sides of the sample over a length of 4 cm, and a load of 500 g was placed thereon.
After leaving in an atmosphere of a temperature of 40 ° C. and a humidity of 85% for 24 hours, a force required for shearing peeling was measured by a tensile tester. The smaller the value is, the more excellent the blocking resistance is. The peel strength is 1.0 kg / 12 cm ² or less.
/ 12 cm ² or more was evaluated as x, and the middle one was evaluated as Δ.

(12) Heat sealability A biaxially oriented polypropylene film having a thickness of 30 μm and a polyurethane adhesive (main ingredient "Takelac" A, manufactured by Takeda Pharmaceutical Co., Ltd.)
-971 / Curing agent "Takenate" A-3 = 9/1) was applied with a coating bar to a thickness of about 4 μm and bonded to the vapor-deposited surface of the metal oxide vapor-deposited unstretched polypropylene film. C. and aged for 2 days to cure. Then, the non-deposited surfaces of the metal oxide vapor-deposited unstretched polypropylene films of the laminated films are superposed on each other, and the sealing temperature is set to 1 by a single-sided heating method with a heat sealer.
Heat sealing was performed under the conditions of 15 ° C., sealing pressure of 1 kg / cm 2 and sealing time of 2 seconds. This heat-sealed sample is cut into a width of 2 cm, and the force required for peeling the sealing surface 90 degrees at a speed of 300 mm / min using a tensile tester (manufactured by Toyo Sokki) is 300 g / cm or more. Was evaluated as ∘, 200 g / cm or less was evaluated as ×, and an intermediate product was evaluated as Δ.

(13) Transparency A bag for packaging is made by the above method, potato chips are put in the bag and sealed, and the color of the potato chip is seen from the outside of the bag to clearly identify the color. Possible things are ○, dark things whose colors cannot be clearly identified are ×, and the middle is △.
Was evaluated.

(14) Secondary workability A biaxially stretched polypropylene film (water vapor transmission rate = 5.0 g / m ² · d) having a thickness of 30 μm and a vapor deposition surface of a metal oxide vapor-deposited unstretched polypropylene film are superposed. Then, through a nip roll cooled to 30 ° C., low density polyethylene (L-705 manufactured by Sumitomo Chemical Co., Ltd.) melted to 300 ° C. is extruded and laminated to a thickness of 20 μm to obtain a laminate. The appearance and water vapor transmission rate of this laminated body were measured, and the laminated body was free of wrinkles and had a water vapor transmission rate of 2.0 g / m 2.
Less than ² · d is ○, wrinkles are included and the water vapor transmission rate is 2.5.
g / m ² · d or more × things, in wrinkles without water vapor transmission rate of 2.0g / m ² · d or more was evaluated of less than 2.5g / m ² · d as △.

[0036]

EXAMPLES The present invention will be described with reference to examples.

Example 1 As the resin of the present invention, ethylene-propylene-butene-
1 random copolymer (EPBC) (ethylene copolymerization amount =
3.2% by weight, butene-1 copolymerization amount = 4.8% by weight, M
FI = 3.8 g / 10 minutes, melting point = 138 ° C.) 92% by weight
And high density polyethylene (HDPE) (MFI = 3.7
g / 10 min, melting point = 132 ° C., density = 0.941) 0.1% by weight of crosslinked polymethylmethacrylate particles (crosslinked PMMA, particle size = 2 μm) was added to a resin composition of 8% by weight, and vented. It is supplied to a mold twin-screw extruder, melted at a temperature of 260 ° C., extruded into a sheet shape with a slit-shaped mouthpiece through a filtration filter, wound around a metal drum heated to a temperature of 50 ° C. and cooled, and a thickness of 25 μm An unstretched film was obtained. The surface of the obtained film to be vapor-deposited was subjected to corona discharge treatment under a treatment condition of 30 W / m ² / min in a mixed gas atmosphere of nitrogen / carbon dioxide, and the film was wound into a roll with a wetting tension of 50 mN / m. I took it. The film temperature at that time was 30 ° C., and the film was allowed to stand for 10 hours to increase the crystallinity and then slit into a small width. The film quality at this time was evaluated and shown in Table 1. Next, the film slit into the narrow width was set in a vacuum vapor deposition apparatus equipped with a film running device, and after a high vacuum of 1.33 × 10 ⁻² Pa was made, the film was run through a cooling metal drum at −20 ° C. It was At this time, while heating and evaporating the aluminum metal, oxygen gas was supplied to the vaporized vapor portion, and aluminum was oxidized to be agglomerated and deposited on the running film surface, and a vapor deposition layer of incomplete aluminum oxide was attached and wound. After the vapor deposition, the inside of the vacuum vapor deposition apparatus is returned to normal pressure, the wound vapor deposition film is slit and aged at a temperature of 50 ° C. for 1 day, then the quality of each film is evaluated, and the characteristics of the film are shown in Table 1. It was Next, the secondary workability of the obtained metal oxide vapor-deposited unstretched film was evaluated, and the characteristics are shown in Table 1. The metal oxide vapor-deposited unstretched film within the scope of the present invention has a high density and a high heat of crystal fusion, and has excellent moisture resistance and transparency after vapor deposition of the metal oxide, and also excellent heat sealability and secondary processability. It was a metal oxide vapor-deposited unstretched film.

Example 2 As the resin of the present invention, ethylene-propylene random copolymer (EPC) (ethylene copolymerization amount = 5% by weight, MF
I = 5.2 g / 10 minutes, melting point = 140 ° C.) 97% by weight
And high density polyethylene (HDPE) (MFI = 4.2
g / 10 min, melting point = 135 ° C., density = 0.938) 3% by weight resin composition, silicon oxide (SiO ² , particle size = 4 μm)
0.1 parts by weight of m) was added to a vent type twin-screw extruder, melted at a temperature of 270 ° C., extruded into a sheet with a slit-shaped die through a filter, and heated to a temperature of 50 ° C. Wrap it around a metal drum and cool it to a thickness of 25
A metal oxide vapor-deposited unstretched film was obtained in the same manner as in Example 1 except that an unstretched film having a thickness of μm was obtained. The obtained unstretched film and the film quality after metal oxide deposition are shown in Table 1.
It was shown to. The metal oxide vapor-deposited unstretched film in the scope of the present invention has a high density, and also has a high heat of crystal fusion, moisture resistance after vapor deposition of the metal oxide, excellent transparency, and heat sealability,
The metal oxide vapor-deposited film was excellent in secondary processability.

Example 3 The same resin composition as in Example 1 was melt extruded into a sheet, and the sheet was wound around a metal drum heated to a temperature of 85 ° C. and cooled to increase the crystallinity, and a thickness of 25 μm was measured. A metal oxide vapor-deposited film was obtained in the same manner as in Example 1 except that the stretched film was obtained. The obtained unstretched film and the film quality after metal oxide deposition are shown in Table 1. The metal oxide vapor-deposited unstretched film within the scope of the present invention has a high density and a high heat of crystal fusion, and is excellent in moisture resistance and transparency after metal oxide vapor deposition, and also in heat sealability and secondary processability. It was a metal oxide vapor-deposited unstretched film.

Comparative Example 1 As the film composition, ethylene-propylene-butene-
1 random copolymer (EPBC) (ethylene copolymerization amount =
2.5% by weight, butene-1 copolymerization amount = 14.0% by weight,
(MFI = 6.5 g / 10 min, melting point = 128 ° C.) A simple substance is melt-extruded into a sheet, and the sheet is wound around a metal drum heated to a temperature of 25 ° C. and cooled to obtain an unstretched film having a thickness of 25 μm. A metal oxide vapor deposition film was obtained in the same manner as in Example 1 except that the above was obtained. The obtained unstretched film and the film quality after metal oxide deposition are shown in Table 1. The metal oxide vapor-deposited unstretched film has a density of 0.895 g.
Since it is as low as / cm ³ and the heat of fusion of crystal is as low as 70 J / g, wrinkles are formed at the time of winding after vapor deposition of metal oxide, and blocking occurs when slitting the vapor deposited film to cause cracks in the vapor deposition layer. Water vapor transmission rate is 3.2
It became as large as g / m ² · d. Further, this film was a metal oxide vapor-deposited unstretched film having a poor secondary processability.

Comparative Example 2 As a film composition, linear rhodity polyethylene (hereinafter abbreviated as LLDPE) (density = 0.921 g)
/ Cm ³ , melting point = 118 ° C.) A single substance was melt extruded into a sheet, wound around a metal drum heated to a temperature of 50 ° C. and cooled to obtain an unstretched film having a thickness of 25 μm. A metal oxide vapor-deposited film was obtained in the same manner as. The quality of the obtained stretched film and the film quality after metal oxide deposition are shown in Table 1. The metal oxide vapor-deposited unstretched film had a high density of 0.921 g / cm ³ , but since the heat of crystal fusion was as low as 67 J / g, wrinkles were formed when the metal oxide was vapor-deposited and wound. Further, when slitting the vapor-deposited film, blocking occurred, cracks were formed in the vapor-deposited film, and the water vapor transmission rate increased to 2.8 g / m ² · d. Further, this metal oxide vapor-deposited unstretched film was also inferior in secondary processability.

Comparative Example 3 When the unstretched film of Example 1 was used to attach a vapor-deposited layer of incomplete aluminum oxide, the ratio of the amount of evaporated aluminum to the amount of oxygen gas supplied was changed to obtain incomplete aluminum oxide. A metal oxide vapor-deposited unstretched film was obtained in the same manner as in Example 1 except that the light transmittance of the vapor deposition film was changed to 50%. The obtained unstretched film and the film quality after metal oxide deposition are shown in Table 1. The metal oxide vapor-deposited unstretched film was inferior in transparency, the contents were difficult to identify when used as a packaging bag, and the film was inferior in practicality.

[0043]

[Table 1]

[0044]

The metal oxide vapor-deposited unstretched film of the present invention exhibits excellent gas barrier properties and transparency by vapor-depositing a specific metal oxide on a film having high density and heat of crystal fusion. In addition, the metal oxide vapor-deposited unstretched film was excellent in secondary processability such as slits and laminates and suitable for various packaging applications.

Claims (2)

[Claims] 1. A film obtained by vapor-depositing a metal oxide on an unstretched film having a film density of 0.9 g / cm ³ or more and a crystal fusion heat amount of 75 J / g or more. A metal oxide vapor-deposited unstretched film having a light transmittance of 60 to 90% and a water vapor transmittance of 2.5 g / m ² · d or less. 2. The metal oxide vapor-deposited unstretched film according to claim 1, wherein the unstretched film is a polymer containing polypropylene as a main component.