GAS BARRIER FILM PRODUCTION METHOD

Abstract

To provide a production method that enables to produce a gas barrier film having excellent transparency and gas barrier properties at high speed. A method for producing a gas barrier film, the gas barrier film having an inorganic thin-film layer laminated to at least one of surfaces of a polymer substrate, in which the inorganic thin-film layer is formed by a vacuum vapor-deposition method using Al and SiO.sub.2 as vapor-deposition materials while introducing oxygen gas.

Claims

1. A method for producing a gas barrier film, the gas barrier film having an inorganic thin-film layer laminated to at least one of surfaces of a polymer substrate, wherein the inorganic thin-film layer is formed by a vacuum vapor-deposition method using Al and SiO.sub.2 as vapor-deposition materials while introducing oxygen gas.

2. The method for producing a gas barrier film according to claim 1, wherein the vapor-deposition materials are heated by an electron gun heating method in the vacuum vapor-deposition method.

3. The method for producing a gas barrier film according to claim 1, wherein, in the vacuum vapor-deposition method, a vacuum vapor-deposition apparatus to be used has a hearth and has a crucible in the hearth, vapor-deposition materials of Al and SiO.sub.2 are partitioned between an inside and an outside of the crucible, and the vapor-deposition materials are heated separately so as to form the inorganic thin-film layer.

4. The method for producing a gas barrier film according to claim 3, wherein, in the vacuum vapor-deposition method, the crucible is mainly made of Al.sub.2O.sub.3.

5. The method for producing a gas barrier film according to claim 1, wherein, in the vacuum vapor-deposition method, oxygen gas is introduced via a pipe.

6. The method for producing a gas barrier film according to claim 5, wherein oxygen gas is supplied between the polymer substrate and the vapor-deposition material via the pipe.

7. The method for producing a gas barrier film according to claim 1, wherein, in the vacuum vapor-deposition method, the vapor-deposition materials are heated by the electron gun heating method, and when time ratios of heating Al and SiO.sub.2 by time division are respectively denoted as a and b, a relation of a<b and 2a>b is satisfied.

8. The method for producing a gas barrier film according to claim 2, wherein, in the vacuum vapor-deposition method, a vacuum vapor-deposition apparatus to be used has a hearth and has a crucible in the hearth, vapor-deposition materials of Al and SiO.sub.2 are partitioned between an inside and an outside of the crucible, and the vapor-deposition materials are heated separately so as to form the inorganic thin-film layer.

9. The method for producing a gas barrier film according to claim 8, wherein, in the vacuum vapor-deposition method, the crucible is mainly made of Al.sub.2O.sub.3.

10. The method for producing a gas barrier film according to claim 9, wherein, in the vacuum vapor-deposition method, oxygen gas is introduced via a pipe.

11. The method for producing a gas barrier film according to claim 10, wherein oxygen gas is supplied between the polymer substrate and the vapor-deposition material via the pipe.

12. The method for producing a gas barrier film according to claim 11, wherein, in the vacuum vapor-deposition method, the vapor-deposition materials are heated by the electron gun heating method, and when time ratios of heating Al and SiO.sub.2 by time division are respectively denoted as a and b, a relation of a<b and 2a>b is satisfied.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a view showing a vacuum vapor-deposition apparatus which is used in Examples 1 and 2 of the present invention.

MODE FOR CARRYING OUT THE INVENTION

[0025] Hereinafter, the present invention will be described in detail.

[0026] A polymer substrate in the present invention is a film-shaped substrate which is obtained by melt-extruding organic polymer, stretching the organic polymer in a longitudinal direction and/or a transverse direction as necessary, and cooling and thermosetting the organic polymer. As the organic polymer, polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, nylon 6, nylon 4, nylon 66, nylon 12, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, wholly aromatic polyamide, polyamide imide, polyimide, polyether imide, polysulfone, polyphenylene sulfide, polyphenylene oxide, and the like can be exemplified. Among the above organic polymers, in the light of low thermal shrinkage and low moisture absorbing expansibility, polyethylene terephthalate is preferable. Also, these kinds of organic polymer may be copolymerized or blended with a small amount of other kind of organic polymer.

[0027] Further, to this organic polymer, publicly known additives such as, for example, a ultraviolet absorber, an anti-static agent, a plasticizer, a lubricant and a coloring agent may be added, and then, transparency of the organic polymer is not limited particularly, but if the organic polymer is used as a transparent gas barrier film, the total light transmittance in the organic polymer is 50% or more, is preferably 70% or more, and is further preferably 85% or more.

[0028] As the polymer substrate of the present invention, the film may be subjected to corona discharge treatment, glow discharge treatment or other surface roughening treatment, and may also be subjected to anchor coat treatment, or may be printed or decorated before laminating a thin-film layer thereto, as far as not losing the object of the present invention.

[0029] The polymer substrate of the present invention has a thickness that preferably ranges from 5 m to 200 m, more preferably ranges from 8 m to 50 m, and particularly preferably ranges from 10 m to 30 m.

[0030] Further, the substrate layer in the present invention may be a laminated film of two layers or more. In the case of adopting as a laminated film, a kind, the number of layers of lamination, a lamination method and the like of the laminate are not limited particularly, and may be selected arbitrarily from publicly known methods according to the purpose.

[0031] The inorganic thin-film layer in the present invention uses Al and SiO.sub.2 as the vapor-deposition materials, and thus mainly contains elements of Al, Si and O, and the ratio of the elements varies according to formation conditions. In addition, in these components, a slight amount (3% or less with respect to the total components) of other component may be contained to an extent that does not lose the properties. A thickness of the inorganic thin-film layer is preferably 5 nm to 100 nm, and is further preferably 7 nm to 40 nm, in the light of the gas barrier properties and flexibility.

[0032] For forming the inorganic thin-film layer, a vacuum vapor-deposition method is adopted. In the present invention, Al and SiO.sub.2 are used as vapor-deposition material sources, and beside Al and SiO.sub.2, silicon monoxide (SiO), aluminum oxide (Al.sub.2O.sub.3) and the like may be mixed. Al can be transformed also into oxide such as AlO and Al.sub.2O.sub.3 by oxidation. SiO.sub.2 can be transformed into silicon or silicon oxide such as SiO or Si by reduction.

[0033] Further, respective particles are required to have an appropriate size so as not to change pressure during the vapor-deposition. A range of the particle size is preferably 3 mm or larger and 20 mm or smaller, and is further preferably 3 mm or larger and 10 mm or smaller. If the particle diameter is too large, evaporation takes time from start of heat application, whereby change of pressure becomes larger. On the other hand, if the particle diameter is too small, explosive boil is caused, and the particles are attached to the film, whereby degradation in quality of appearance may be caused, or flaws may be generated to the thin-film.

[0034] The respective vapor-deposition materials are partitioned by a crucible in a hearth. Since Al has high thermal conductance, heat conducts between Al particles quicker than the temperature of Al particles reaching an evaporating temperature, whereby the temperature is increased to the evaporating temperature after liquefying all of the Al particles. Thus, if the materials are divided just by the partition plate, liquid Al may flow through a gap or the like. By partitioning the materials by the crucible, it is possible not only to decrease thermal dispersion so as to increase heating efficiency, but also to inhibit outflow of the liquid Al. A kind of the crucible is not limited particularly, but for example, a crucible that is mainly made of Al.sub.2O.sub.3 is preferable, and a crucible which is mainly made of Al.sub.2O.sub.3 and has holes is further preferable, in the light of heat resistance and thermal insulation.

[0035] Thin-film formation speed during the vapor-deposition is preferably 100 m/min or more in the light of the production cost. Further, the evaporation speed of the materials is not limited particularly, because it is necessary to be changed according to the thin-film formation speed, but the evaporation speed that is calculated by a calculation method described in below-described Examples preferably ranges from 15 m/min/A to 200 m/min/A, further preferably ranges from 15 m/min/A to 100 m/min/A, and particularly preferably ranges from 20 m/min/A to 80 m/min/A. If the evaporation speed is too low, the thin-film formation speed cannot be increased, and if the evaporation speed is too high, control of the pressure becomes difficult.

[0036] A weight ratio of Al atoms:Si atoms is preferably within a range from 10:90 to 50:50, and is further preferably within a range from 20:80 to 40:60. If the Al ratio is too low, the gas barrier properties are not exhibited, and the Al ratio is too high, the thin-film is likely to be colored, so that the application as the transparent gas barrier film is limited.

[0037] As a heating method, an electron gun heating method is preferable, because it has a merit that a heating quantity change quickly responds to a change of scanning and a current value, but the heating method is not limited to this method, and resistance heating, high frequency induction heating, laser heating and the like can also be adopted. Further, reactive gas can be introduced into a thin-film formation apparatus. In this case, the reactive gas to be introduced is preferably transformed into plasma. As the reactive gas, oxygen gas is used, and beside the oxygen gas, nitrogen, hydrogen, water vapor or the like may be introduced, and means such as ozone addition and ion assist may also be adopted thereto.

[0038] When the vapor-deposition materials are heated by the electron gun heating method, if time ratios of heating Al and SiO.sub.2 by time division are respectively denoted as a and b, preferably the relation of a<b and 2a>b is satisfied. More preferably, the relation of a<b and 1.5a b is satisfied. If the vapor-deposition is carried out in the condition of a>b, the thin-film is likely to be colored, but in the condition of 2a<b, an evaporation amount of SiO.sub.2 becomes excessive, and the vapor-deposited particles are considered to inhibit a reaction between Al and oxygen gas.

[0039] FIG. 1 illustrates the vacuum vapor-deposition apparatus of the present invention. In a vacuum chamber 1, an unwinding portion 3 and a winding portion 4 are disposed via a cooling drum 2 and guide rolls 5. The two guide rolls are illustrated, but the number of the guide rolls is not limited to this.

[0040] The reactive gas is introduced into the vacuum chamber 1 using a pipe 11. A shape of the pipe and the gas introduction position of the pipe are not limited particularly, but in the light of the reactivity, it is preferable to dispose the pipe so that the gas may be supplied between a crucible 9 in which the vapor-deposition material is disposed and the cooling drum 2 on which the substrate runs, as shown by a reactive gas introduction direction 12. Further, the pipe 11 is preferably covered with an attachment prevention plate 13 so that the vapor-deposition materials may not be attached thereto.

[0041] An introduction mount of the oxygen gas is not limited particularly, because it is changed according to the evaporation amount of the vapor-deposition materials, but it is preferably adjusted so that pressure in the vacuum chamber 1 during the thin-film formation may be 5.010.sup.1 Pa or lower, and further preferably, the pressure may be 1.010.sup.1 Pa or lower.

[0042] An emission current of the electron gun is preferably 0.3 A or higher and 1.5 A or lower, is further preferably 0.3 A or higher and 1.0 A or lower, and is more preferably 0.3 A or higher and 0.8 A or lower. If the emission current is lower than 0.3 A, sufficient evaporation speed cannot be obtained, thereby decreasing the productivity. On the other hand, if the emission current is too high, decomposition of the silicon oxide becomes large, whereby control of the pressure becomes difficult.

[0043] In the present invention, the thin-film may be formed only on one of surfaces of the plastic film, but may be formed on both of the surfaces. Further, the formation conditions may be changed by adding a bias to the substrate or the like, as far as not losing the object of the present invention.

[0044] The gas barrier film produced by the production method of the present invention may be used as it is, and may also be used after being laminated or coated with a film or a thin layer of other organic polymer.

[0045] For example, in the case of using the gas barrier film produced by the production method of the present invention for packaging, it may be laminated with various kinds of films or paper depending on properties required for a content to be packaged, and as a representative laminate configuration thereof, the gas barrier film (PET upper side)/PE, the gas barrier film (PET upper side)/CPP, NY/the gas barrier film (PET upper side)/PE, the gas barrier film (NY upper side)/PE and the like can be considered. A lamination method thereof is not limited particularly, but dry lamination, an extrusion lamination method and the like are preferable. Further, decoration and printing for content description may be added thereto, or a design film, a reinforcing material and the like may be adhered thereto.

[0046] As the gas barrier properties of the laminate of the present invention, an oxygen permeation amount under the environment at a temperature of 23 C. and relative humidity of 65% RH is preferably 1.0 ml/m.sup.2/24 H/MPa or higher and 100 ml/m.sup.2/24 H/MPa or lower. It is less preferable that the gas barrier properties are higher than 100 ml/m.sup.2/24 H/MPa, because such a laminated body is hard to be used for food, pharmaceutical products, industrial products and the like. Further, although the lower the gas barrier properties are, the better, a lower limit of the barrier properties in the present configuration is 1.0 ml/m.sup.2/24 H/MPa in the current technical level, and even gas barrier properties of 1.0 ml/m.sup.2/24 H/MPa are practically sufficient. A more preferable range thereof is 1.0 ml/m.sup.2/24 H/MPa or higher and 70 ml/m.sup.2/24 H/MPa or lower, and a particularly preferable range is 1.0 ml/m.sup.2/24 H/MPa or higher and 30 ml/m.sup.2/24 H/MPa or lower.

EXAMPLES

[0047] The present invention will be specifically described below by way of examples, but the present invention is not limited to the examples.

[0048] Hereinafter, measurements and operating procedures carried out in the examples will be described.

[0049] 1) Calculation of Thin-Film Thickness and Ratio of Al and Si

[0050] A thin-film thicknesses and a ratio of Al and Si were measured by using an X-ray fluorescence spectrometer (System 3270 produced by Rigaku Corporation). X-rays were generated by a rhodium bulb at 50 kV and 50 mA, and a composite thin-film of Al.sub.2O.sub.3/SiO.sub.2 was quantified using a calibration curve which was formed based on samples with different composition ratios.

[0051] 2) Calculation of Evaporation Speed

[0052] Evaporation speed (hereinafter, abbreviated as ES) was obtained by using a following formula.

Evaporation Speed: ES=T/(0.15/(LS/60))60/1000/A

[0053] Herein, T denotes a thin-film thickness (nm), LS denotes thin-film formation speed (m/min), and A denotes a current value (A) of EB.

[0054] 3) Oxygen Permeability

[0055] Oxygen permeability of the formed gas barrier film was measured by an oxygen permeability measurement device (OX-TRAN100 produced by ModernControls, Inc.) under conditions at 23 C. and 65% R.H.

[0056] 4) Light Transmittance

[0057] Total light transmittance was measured by a hazemeter (hazemeter produced by NIPPON DENSHOKU INDUSTRIES CO., LTD, NDH5000).

Example 1

[0058] A composite oxide thin-film was formed on a PET film (TOYOBO CO., LTD.: E5100) with a thickness of 12 m by a vacuum vapor-deposition apparatus shown in FIG. 1, using particulate Al (purity: 99.9%) of about 7 mm to about 9 mm and SiO.sub.2 (purity: 99.9%) of about 4 mm to about 7 mm as vapor deposition sources. The above-described two kinds of the vapor-deposition materials were not mixed but were partitioned by putting Al into a crucible which was made of Al.sub.2O.sub.3 and had holes and putting SiO.sub.2 around the crucible in a hearth. One electron gun was used as a heat source so as to heat each of Al and SiO.sub.2 by time division. An output of electron beams was 0.7 A, a heating ratio (time ratio) of Al and SiO.sub.2 was 40:60, and feeding speed of the film was 150 m/min, thereby forming the composite thin-film with a thickness of 26.7 nm. A flow rate of oxygen gas was 50 sccm, and pressure during the vapor-deposition was 6.010.sup.2 Pa. Further, a temperature of a coating roll for cooling the film during the vapor-deposition was adjusted at 10 C., thereby obtaining the gas barrier film of the present invention. These thin-film formation conditions will be shown in Table 1.

[0059] A thin-film thickness and a ratio of Al and Si of the thus obtained gas barrier film were measured by an X-ray fluorescence spectrometer, oxygen permeability was measured as the gas barrier properties, and light transmittance was measured as an optical property. These measurement results will be shown in FIG. 2.

Example 2

[0060] A composite oxide thin-film was formed on a PET film (TOYOBO CO., LTD.: E5100) with a thickness of 12 m by the vacuum vapor-deposition apparatus shown in FIG. 1, using particulate Al (purity: 99.9%) of about 7 mm to about 9 mm and SiO.sub.2 (purity: 99.9%) of about 4 mm to about 7 mm as the vapor deposition sources. The above-described two kinds of the vapor-deposition materials were not mixed but were partitioned by putting Al into a crucible made of MgO and putting SiO.sub.2 around the crucible in a hearth. One electron gun was used as a heat source so as to heat each of Al and SiO.sub.2 by time division. An output of electron beams was 0.6 A, a heating ratio (time ratio) of Al and SiO.sub.2 was 49:51, and feeding speed of the film was 120 m/min, thereby forming the composite thin-film with a thickness of 13.6 nm. A flow rate of oxygen gas was 150 sccm, and pressure during the vapor-deposition was 1.010.sup.1 Pa. Further, a temperature of a coating roll for cooling the film during the vapor-deposition was adjusted at 10 C., thereby obtaining the gas barrier film of the present invention. These thin-film formation conditions will be shown in Table 1.

[0061] A thin-film thickness and a ratio of Al and Si of the thus obtained gas barrier film were measured by an X-ray fluorescence spectrometer, oxygen permeability was measured as the gas barrier properties, and light transmittance was measured as the optical property. These measurement results will be shown in FIG. 2.

Comparative Example 1

[0062] A composite oxide thin-film was formed on a PET film (TOYOBO CO., LTD.: E5100) with a thickness of 12 m by the vacuum vapor-deposition apparatus shown in FIG. 1, using particulate Al (purity: 99.9%) of about 7 mm to about 9 mm and SiO.sub.2 (purity: 99.9%) of about 4 mm to about 7 mm as the vapor deposition sources. The above-described two kinds of the vapor-deposition materials were not mixed, but an inside of a hearth was partitioned into two by a carbon plate so as to separate the materials. One electron gun was used as a heat source so as to heat each of Al and SiO.sub.2 by time division. An output of electron beams was 2.0 A, a heating ratio (time ratio) of Al and SiO.sub.2 was 11:89, and feeding speed of the film was 50 m/min, thereby forming a thin-film with a thickness of 79 nm. A flow rate of oxygen gas was 100 sccm, and pressure during the vapor-deposition was 1.110.sup.1 Pa. Further, a temperature of a coating roll for cooling the film during the vapor-deposition was adjusted at 10 C., thereby obtaining the gas barrier film of the present invention. These thin-film formation conditions will be shown in Table 1. The obtained gas barrier film was subjected to measurements similar to those of Example 1. The measurement results will be shown in FIG. 2.

Comparative Example 2

[0063] A composite oxide thin-film was formed on a PET film (TOYOBO CO., LTD.: E5100) with a thickness of 12 m by the vacuum vapor-deposition apparatus shown in FIG. 1, using particulate Al (purity: 99.9%) of about 7 mm to about 9 mm and SiO.sub.2 (purity: 99.9%) of about 4 mm to about 7 mm as the vapor deposition sources. The above-described two kinds of the vapor-deposition materials were not mixed, but an inside of a hearth was partitioned into two by a carbon plate so as to separate the materials. One electron gun was used as a heat source so as to heat each of Al and SiO.sub.2 by time division. An output of electron beams was 2.0 A, a heating ratio (time ratio) of Al and SiO.sub.2 was 9:91, and feeding speed of the film was 50 m/min, thereby forming a thin-film with a thickness of 85 nm. A flow rate of oxygen gas was 300 sccm, and pressure during the vapor-deposition was 1.310.sup.1 Pa. Further, a temperature of a coating roll for cooling the film during the vapor-deposition was adjusted at 10 C., thereby obtaining the gas barrier film of the present invention. These thin-film formation conditions will be shown in Table 1. The obtained gas barrier film was subjected to measurements similar to those of Example 1. The measurement results will be shown in FIG. 2.

Comparative Example 3

[0064] A composite oxide thin-film was formed on a PET film (TOYOBO CO., LTD.: E5100) with a thickness of 12 m by the vacuum vapor-deposition apparatus shown in FIG. 1, using particulate Al (purity: 99.9%) of about 7 mm to about 9 mm and SiO.sub.2 (purity: 99.9%) of about 4 mm to about 7 mm as the vapor deposition sources. The above-described two kinds of the vapor-deposition materials were not mixed, but an inside of a hearth was partitioned into two by a carbon plate so as to separate the materials. One electron gun was used as a heat source so as to heat each of Al and SiO.sub.2 by time division. An output of electron beams was 2.0 A, a heating ratio (time ratio) of Al and SiO.sub.2 was 11:89, and feeding speed of the film was 50 m/min, thereby forming a thin-film with a thickness of 78 nm. A flow rate of oxygen gas was 60 sccm, and pressure during the vapor-deposition was 6.010.sup.2 Pa. Further, a temperature of a coating roll for cooling the film during the vapor-deposition was adjusted at 10 C., thereby obtaining the gas barrier film of the present invention. These thin-film formation conditions will be shown in Table 1. The obtained gas barrier film was subjected to measurements similar to those of Example 1. The measurement results will be shown in FIG. 2.

TABLE-US-00001 TABLE 1 Thin-film formation Current Oxygen speed value flow rate Pressure Heating ratio (m/min) (A) (sccm) (Pa) Partition a b Example 1 150 0.7 50 0.06 Al.sub.2O.sub.3 crucible 40 60 Example 2 120 0.6 150 0.10 MgO crucible 49 51 Comparative 50 2.0 100 0.11 Carbon plate 11 89 Example 1 Comparative 50 2.0 300 0.13 Carbon plate 9 91 Example 2 Comparative 50 2.0 60 0.06 Carbon plate 11 89 Example 3

TABLE-US-00002 TABLE 2 Composition ratio Oxygen Al % Si % Evaporation permeability Total light by by Thin-film speed (ml/m.sup.2/ transmittance mass mass thickness (nm) (m/min/A) 24 H/MPa) (%) Example 1 26 74 26.7 38.1 8.4 88 Example 2 44 56 13.6 18.1 25.8 84 Comparative 38 62 79.0 13.2 5.2 86 Example 1 Comparative 4 96 85.0 14.2 72.0 88 Example 2 Comparative 50 50 78.0 13.0 4.1 86 Example 3

[0065] Table 2 shows that the gas barrier films obtained in Examples 1 to 2 were formed at the high evaporation speed, which were as high as 38.1 m/min/A and 18.1 m/min/A, respectively. Further, the gas barrier films obtained in Examples 1 to 2 exhibited the oxygen permeability of 30 ml/m.sup.2/24 H/MPa or less and the total light transmittance of 80% or more, and thus had sufficient performances as transparent gas barrier films. On the other hand, in Comparative Examples 1 to 3, since the two kinds of the vapor-deposition materials were partitioned by the carbon plate, the heating efficiency was low, so that the evaporation speed was as low as 13.0 m/min/A to 14.2 m/min/A.

INDUSTRIAL APPLICABILITY

[0066] The present invention enables to produce a gas barrier film having excellent gas barrier properties and transparency at high speed, and thus can be used favorably as a method for producing a packaging film, which is used in a packaging field for food, pharmaceutical products, precise electronic components and the like.

DESCRIPTION OF REFERENCE SIGNS

[0067] 1 VACUUM CHAMBER [0068] 2 COOLING DRUM [0069] 3 UNWINDING PORTION [0070] 4 WINDING PORTION [0071] 5 GUIDE ROLL [0072] 6 SUBSTRATE FILM [0073] 7 INORGANIC THIN-FILM LAYER LAMINATE [0074] 8 ELECTRON GUN [0075] 9 HEARTH [0076] 10 VACUUM PUMP [0077] 11 REACTIVE GAS INTRODUCTION PIPE [0078] 12 REACTIVE GAS INTRODUCTION DIRECTION [0079] 13 ATTACHMENT PREVENTION PLATE