JP3396943B2 - Manufacturing method of gas barrier metal vapor deposited film - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metallized film. More particularly, excellent in barrier properties of gases such as oxygen and water vapor, in particular, suitable for food packaging such as gas barrier
The present invention relates to a method for producing a metal evaporated film. Heretofore, vacuum deposition of a metal such as aluminum or a metal compound on a plastic film has been widely used for gold and silver threads, capacitors, food packaging materials and the like. However, these vapor-deposited films are generally simply vacuum-deposited on a plastic film or the like as a substrate, and thus have problems such as weak adhesion to the substrate, and various improvement methods are being studied. For example, as a method for producing a vapor-deposited film in which a plastic film is treated in a low-temperature plasma atmosphere and then a metal is vapor-deposited, JP-B-52-25868, JP-A-63-242534, JP-A-63-270455, JP-A-63-270455, There are proposals such as 3-247750. [0004] However, the main purpose of such a conventional vapor-deposited film obtained by depositing a metal after treatment in a low-temperature plasma atmosphere is to increase the adhesion between the vapor-deposited film and the substrate. Was not taken into account. These proposals have the following problems. JP-B-52-25868, JP-A-63-2
In the method by sputtering and the processing in a low-temperature plasma atmosphere described in 42534, there is a gap between the pressure of the sputtering or the low-temperature plasma processing and the pressure at the time of metal evaporation, and the sputtering, the low-temperature plasma processing and the evaporation are simultaneously performed in the same tank. Cannot do it. JP-A-63-2
The method of maintaining the film surface temperature of 70455 at or below the glass transition temperature is costly to implement when the glass transition temperature of a polypropylene film or the like is below the freezing point, and the effect of improving gas barrier properties is small. Also, JP-A-3-247750.
In the method described in the above, the pressure during the discharge process is high,
A dense metal vapor deposition film cannot be formed, and sufficient gas barrier properties cannot be obtained. [0006] In recent years, as eating habits have become richer and various foods and confectioneries have appeared on the market, improvement in quality and long-term preservation of quality have become even more important. It has become In particular, in the packaging of snacks and the like, gas barrier properties more than ever before have been demanded in order to prevent the contents from being oxidized and wet and to secure freshly prepared quality for a longer period of time. [0007] The present invention aims at remarkably improving the gas barrier properties of oxygen and water vapor of such a vapor-deposited film, whereby low-temperature plasma treatment and vapor deposition can be stably performed on a general-purpose plastic film in the same tank for a long time, and An object of the present invention is to produce a gas-barrier metal-deposited film having excellent gas- barrier properties for oxygen and water vapor. According to the present invention, a surface of a substrate made of a plastic film is coated with a magnetron electrode coated with a metal selected from Ti, Pd, and Al by using an 8 × 10 low temperature plasma treatment at a pressure and 10 W · min / m ² or more processing intensity of ^-1 Pa or less, and providing a metal deposition film is continuously on the treated surface gas
This is a method for producing a metallized barrier film. The plastic film referred to in the present invention is:
It is obtained by melting or melt-extruding an organic polymer and stretching it in the longitudinal direction and / or the width direction as necessary.
Examples of the organic polymer include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyamides such as nylon 6, nylon 66, and nylon 12, vinyl chloride, vinylidene chloride, and polyvinyl alcohol. Aromatic polyamide, polyamide imide, polyimide, polyether imide, polysulfone, polyether sulfone, polyether ether ketone, polyarylate, polyphenylene sulfide,
Polyphenylene oxide, tetrafluoroethylene,
Examples thereof include ethylene monochloride trifluoride and fluorinated ethylene propylene copolymer. [0010] These copolymers, copolymers with other organic polymers, and those containing other organic polymers may be used. Known additives to these organic polymers, for example, antistatic agents, ultraviolet absorbers, plasticizers,
A lubricant, a coloring agent, and the like may be added. In particular, it can be used as the most effective means for biaxially oriented polypropylene films and biaxially oriented polyethylene terephthalate films stretched in the longitudinal and width directions. [0011] The thickness of the plastic film of the present invention is:
There is no particular limitation, but from the suitability as a packaging material
A range of 200 μm is desirable. In terms of mechanical properties and flexibility, it is more preferable that the thickness be in the range of 5 to 100 μm. Most preferably, it is 8 to 30 μm. A metal film is formed on at least one surface of the plastic film by a vacuum deposition method.
As the metal of the raw material, a metal such as Al, Zn, Mg, or Sn is preferable, and Ti, In, Cr, Ni, Cu, Pb, or F
e can also be used. Of these, Al is most preferable in terms of productivity and cost. The method of vacuum evaporation according to the present invention is to evaporate metal from an evaporation source to form an evaporation film on a substrate film. For this purpose, the evaporation source may be a boat of resistance heating type, radiant or high frequency. There are a crucible method by heating and a method by electron beam heating, but there is no particular limitation. In the present method, the pressure of the deposition section in the vacuum apparatus is determined by the gloss of the metal film, the denseness of the metal film, the surface electric resistance,
It has been clarified by the present invention that it greatly affects the gas barrier property. In order to obtain a metal vapor-deposited film having excellent gas barrier property, the pressure of the vapor deposition section must be 1.33 × 10 3
It must be performed at a pressure of ^-2 Pascal or less. Normally, a vacuum evacuation apparatus is differentially evacuated, and it is necessary to perform low-temperature plasma processing at a pressure of 8 × 10 ⁻¹ pascal or less in order to maintain the pressure in the vapor deposition section. More preferably, 6 × 10 ^{- 1} Pa or less pressure is desirable. In order to perform vacuum deposition at such a pressure,
In the pretreatment low-temperature plasma treatment performed in the same vacuum chamber, it is necessary to select a planar magnetron electrode or a coaxial cylindrical magnetron electrode as a discharge electrode in terms of stability of plasma discharge, treatment intensity, and the like. The power supply frequency for performing this discharge can be selected from the range of direct current to radio frequency, but direct current (DC) is most preferable because of easy introduction of power and stability of discharge. The selection of the material of the magnetron electrode is most important. The material of the metal covering the electrodes is Ti, Pd, Al
Is selected from Other metals such as those obtained by vapor deposition or plating on a metal such as Cu can also be used. Other metals such as C
When u or stainless steel is on the surface, the gas barrier property, particularly the water vapor barrier property is not sufficient, and sometimes the water vapor barrier property is worse than when no treatment is performed. It is important that the flow rate of the gas introduced at the time of the low-temperature plasma treatment using such an electrode is set to the lowest flow rate at which plasma discharge is started in order to minimize the rise in the pressure of the vapor deposition tank. Desirably, a cover as shown in FIG. 1 is provided in the region where the plasma processing is performed, and more stable plasma discharge processing can be performed by increasing the pressure only in the plasma processing region compared to the deposition layer. The processing strength of the low-temperature plasma processing is expressed by power (W) × unit time (1 minute) per unit area (1 m ² ), that is, E value.
Gas barrier properties are improved. In order to obtain excellent gas barrier properties, a processing strength of 10 W · min / m ² or more is desirable.
In the low-temperature plasma treatment of the present invention, the treatment at a position in contact with the cooling drum immediately before the metal is deposited on the plastic film as the substrate to be treated has a small heat loss of the substrate film and a treatment effect on gas barrier properties. Is preferred. The thickness of the deposited metal film is preferably in the range of 10 to 200 nm from the viewpoint of gas barrier properties and flexibility. If the thickness is less than 10 nm, the gas barrier properties, particularly the oxygen barrier properties, are not sufficient.
Heat loss at the time of vapor deposition and the flexibility of the metal film are deteriorated, and furthermore, cracking and peeling are likely to occur due to bending and the like. More preferably, it is 20 to 100 nm. Hereinafter, the present invention will be described in detail with reference to the drawings. An example of the method for producing a metallized film of the present invention will be described with reference to FIG. The plastic film 5 unwound from the film unwinding shaft 2 installed in the vacuum vessel 1 is -3.
The film is wound around a film winding shaft 4 while traveling along a heating / cooling drum 3 whose temperature is controlled to 0 ° C. to 60 ° C. At the same time, the metal is evaporated from the crucible 7 in the evaporator 6 and deposited on the plastic film 5. A magnetron electrode 8 is provided before the metal is deposited, and low-temperature plasma processing is performed in the electrode cover 9 while introducing carbon dioxide from the low-temperature plasma processing gas cylinder 11 to the gas flow control device 10. Method for Measuring Physical Properties and Method for Evaluating Effects The characteristic values of the present invention are determined by the following methods. (1) Oxygen Permeability According to ASTM D-3985, oxygen permeability was measured at 20 ° C. and 0% RH using an oxygen permeability measuring device OX-TRAN100 manufactured by Modern Control. (2) Water vapor transmission rate “PERMAT”, a water vapor transmission rate meter manufactured by Modern Control Co., Ltd.
The measurement was carried out using RAN "-W1A under the conditions of 40 ° C. and 90% RH. EXAMPLES Examples are described below: Example 1 Biaxially stretched polyethylene terephthalate of a packaging type. Using a film (“Lumirror” type P60, manufactured by Toray Industries, Inc., thickness 12 μm) as a base, a vacuum evaporation method
An aluminum film was formed. An electron beam heating type vacuum evaporator was used for 2 × 10
After evacuating to ⁻³ Pascal, carbon dioxide gas was introduced to a pressure of 4 × 10 ⁻¹ Pascal, and low-temperature plasma treatment was performed using a Ti DC planar magnetron electrode at an E value of 100 W · min / m ^2. Subsequently, vacuum deposition of aluminum was performed. In vacuum deposition, alumina crucible (Nippon Carbon Serum Co., Ltd.) is filled with granular aluminum (Purity 99.99%, manufactured by Vacuum Metallurgy Co., Ltd.)
Aluminum was evaporated while being heated and melted by an electron beam to form an aluminum film having a thickness of 30 nm. At this time, the temperature of the film cooling drum was 30 ° C. This aluminum deposited film was used as Example 1. Example 2 and Example 3 The low-temperature plasma treatment intensity of Example 1 was set to 20 W · min / m ² ,
The aluminum vapor-deposited films at 200 W · min / m ² were referred to as Example 2 and Example 3, respectively. Example 4 Instead of the biaxially oriented polyethylene terephthalate film of the packaging type in Example 1, a biaxially oriented polypropylene film of the packaging type ("Trefane" manufactured by Toray Industries, Inc.)
Example 4 was an aluminum vapor-deposited film having a substrate of type Y746 (thickness: 18 μm). Embodiment 5 and Embodiment 6 The low-temperature plasma treatment intensity of Embodiment 4 was set to 20 W · min / m ² ,
The aluminum vapor-deposited films at 200 W · min / m ² are referred to as Example 5 and Example 6, respectively. Example 7 An aluminum vapor-deposited film obtained by performing the low-temperature plasma treatment of Example 4 using a Pd-made planar magnetron electrode was used as Example 7. Example 8 An aluminum vapor-deposited film obtained by performing the low-temperature plasma treatment of Example 4 using a coaxial magnetron electrode made of Ti was used as Example 8. Example 9 An aluminum vapor-deposited film obtained by performing the low-temperature plasma treatment of Example 4 using a coaxial magnetron electrode made of Al was used as Example 9. COMPARATIVE EXAMPLE 1 The aluminum-deposited film which was not subjected to the low-temperature plasma treatment in Example 1 was used as Comparative Example 1. Comparative Example 2 The processing intensity of the low-temperature plasma processing of Example 1 was 5 W · min / m
^The aluminum vapor-deposited film designated as No. 2 was used as Comparative Example 2. COMPARATIVE EXAMPLE 3 Comparative Example 3 was made of the aluminum-deposited film which was not subjected to the low-temperature plasma treatment in Example 4. Comparative Example 4 The processing intensity of the low-temperature plasma processing of Example 4 was 5 W · min / m
^The aluminum vapor-deposited film of No. ² was used as Comparative Example 4. The increased carbon dioxide introduction amount of Comparative Example 5 Example 4 was a comparative Example 5 An aluminum deposited film when subjected to low-temperature plasma treatment at a pressure 1 × 10 ⁰ Pa. Comparative Example 6 An aluminum vapor-deposited film obtained by performing the low-temperature plasma treatment of Example 4 using a Cu planar magnetron electrode was used as Comparative Example 6. COMPARATIVE EXAMPLE 7 A comparative example 7 was produced by depositing an aluminum film on which the low-temperature plasma treatment of Example 4 was performed using a stainless steel coaxial magnetron electrode. Examples 1 to 9 and Comparative Examples 1 to 7
Are shown in Table 1. [Table 1] According to the method for producing a metal-deposited film of the present invention, a film having excellent gas barrier properties can be produced stably and inexpensively. By utilizing the gas barrier properties, it can be widely used as a packaging material for foods, pharmaceuticals, electronic parts, mechanical parts, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an example of a vacuum evaporation apparatus provided with a low-temperature plasma processing magnetron electrode for carrying out the manufacturing method of the present invention. [Description of Signs] 1: Vacuum container 2: Film unwinding shaft 3: Heating / cooling drum 4: Film winding shaft 5: Plastic film 6: Evaporator 7: Crucible 8: Magnetron electrode 9: Electrode cover 10: Gas flow rate Control device 11: gas cylinder for low-temperature plasma processing

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23C 14/00-14/58 B32B 15/08

Claims (1)

(57) [Claims 1] The surface of a substrate made of a plastic film is 8 × 10 ⁻¹ using a magnetron electrode coated with a metal selected from Ti, Pd and Al. A method for producing a gas-barrier metal vapor-deposited film, comprising: performing low-temperature plasma processing at a pressure of not more than Pascal and a processing intensity of 10 W · min / m ² or more, and continuously providing a metal vapor-deposited film on the processed surface.