JPH04165064A - Production of transparent gas barrier film - Google Patents

Abstract

PURPOSE:To stably produce a transparent gas barrier film excellent in gas barrier property by providing a silicon oxide film on the surface of a plastic film by the reactive vapor deposition of Si in a carbon crucible. CONSTITUTION:A gaseous mixture contg. O2 is introduced into a vacuum system to carry out the reactive vapor deposition of metallic Si in a carbon crucible. A silicon oxide film expressed by SiOx (x=1.0 to 2.0) is provided on at least one surface of the substrate consisting of a PE film, etc., by this reactive vapor deposition. The thickness of the film is preferably controlled to about 200-3000Angstrom . Consequently a transparent gas barrier film capable of excellently obstructing steam, O2, etc., is stably, uniformly, inexpensively and continuously obtained for a long time.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a transparent gas barrier film.

More specifically, the present invention relates to a transparent gas barrier film that has excellent barrier properties against gases such as water vapor and oxygen, and excellent light transparency, and is particularly suitable for packaging pharmaceuticals and foods.

[Prior Art] Conventionally, transparent gas barrier films deposited with silicon oxide are disclosed in JP-A-49-41469 and JP-A-54-1.
52089, JP-A-60-157852, JP-A-63-
86860, JP-A-1-176069, etc. are known.

[Problems to be Solved by the Invention] However, the conventional gas barrier film deposited with silicon oxide and its manufacturing method have the following problems.

Regarding products made from silicon dioxide, ■ Gas barrier properties are not exhibited.

■ During vapor deposition, the raw materials in the crucible do not melt uniformly;
Film thickness control is difficult.

- Regarding materials made from silicon oxide, ■ - Since silicon oxide is a sublimable material, it evaporates in a flash, making it difficult to control the film thickness, and it is not suitable for electron beam (E B) evaporation. do not have.

Regarding materials made from metallic silicon, ■ In alumina or magnesia crucibles, stable vapor deposition cannot be achieved because metallic silicon reacts with alumina or magnesia inside the crucible, causing bumping.

The present inventors have arrived at the present invention as a result of extensive research into a transparent gas barrier film that can be deposited stably over a long period of time and has excellent barrier properties against gases such as water vapor and oxygen.

[Means for Solving the Problems] That is, the present invention provides (1) using silicon metal as a raw material to deposit Si onto at least one surface of a substrate made of a plastic film by a reactive vapor deposition method using a carbon crucible.
A method for producing a transparent gas barrier film characterized by providing a silicon oxide film represented by Ox (X = 1.0 to 2.0), (2) reacting while introducing a mixed gas containing oxygen into a vacuum system; The above (1) characterized in that a chemical vapor deposition is performed.
) provides a method for producing a transparent gas barrier film according to item 1.

Hereinafter, the present invention will be explained in detail using the drawings.

Here, a method for producing a transparent gas barrier film of the present invention will be outlined with reference to FIG. 1.

The plastic film 5 unwound from the film unwinding shaft 2 installed in the vacuum container 1 is wound around the film winding shaft 4 while traveling along the cooling drum 3 cooled to -30°C to 10°C. taken.

At the same time, metal silicon (not shown) is evaporated from the crucible 7 in the evaporator 6, and oxygen gas is supplied from the oxygen gas cylinder 10 through the gas flow control device 9 and the gas outlet 8. Evaporated silicon and oxygen gas react to form a silicon oxide film on the surface of the plastic film 5.

The plastic film referred to in the present invention is a film obtained by melting or extruding an organic polymer and stretching the film in the longitudinal direction and/or width direction as necessary. Examples of organic polymers include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyamides such as nylon 6 and nylon 12, vinyl chloride, vinylidene chloride, polyvinyl alcohol, and aromatic polyamides. , polyamideimide, polyimide, polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, polyarylate, polyphenylene sulfide, polyphenylene oxide, tetrafluoroethylene, trifluoroethylene monochloride, fluorinated ethylene propylene copolymer, etc. can be given.

Moreover, these copolymers or copolymers with other organic polymers may be used, or they may contain other organic polymers. Known additives such as antistatic agents, ultraviolet absorbers, plasticizers, lubricants, colorants, etc. may be added to these organic polymers.

The light transmittance of the plastic film of the present invention is important for the visibility and aesthetic appearance of the package contents, and the total light transmittance in white light is at least 40% or more, preferably 60%.
Above, it is most preferably 80% or more. Known additives such as colorants are preferably added within this range. Prior to forming the metal oxide layer, the plastic film of the present invention undergoes corona discharge treatment, plasma treatment,
Surface treatments such as glow discharge treatment, reverse sputtering treatment, and surface roughening treatment may be performed.

The thickness of the plastic film of the present invention is not particularly limited, but a range of 3 to 200 μm is desirable from the viewpoint of suitability as a packaging material. In terms of mechanical properties and flexibility, the thickness is more preferably in the range of 5 to 100 μm.

On at least one side of such a plastic film,
By reactive vapor deposition method, Si
A silicon oxide film represented by Ox (X=1.0-2.0) is formed.

The silicon metal is preferably processed into particles, rods, tablets, wires, or crucibles with a purity of 99% or more, preferably 99.5% or more, with few impurities.

In addition, the crucible used for reactive vapor deposition of metallic silicon is
It must be made of carbon, and in alumina or magnesia crucibles that are normally used for vapor deposition of metals such as aluminum, metal silicon reacts and bumps, forming a continuous silicon oxide film on the plastic film. I can't do that.

The carbon crucible is preferably used by molding or extruding carbonaceous carbon, graphite carbon, etc., and then cutting the crucible into a shape such as a cylinder, rectangular parallelepiped, or trapezoid. Extrusion-molded graphite carbon has a small coefficient of thermal expansion and is therefore preferred since it is less likely to cause cracks in the crucible. In addition, graphite carbon molded using Nippon Carbon Ceram's isotropic processing method has particularly excellent hardness.

In this reactive vacuum deposition method in which silicon metal is placed in a carbon crucible, the pressure inside the vacuum apparatus greatly affects the transparency and gas barrier properties of the silicon oxide layer.
It has become clear according to the present invention, and preferably lXl
0-7 to lXl0-2 torr, more preferably lXl
0-6 to 5X10-3 torr, most preferably lXl
A range of 0-5 to 1 x 10-3 Torr is desirable.

The gas composition during reactive vapor deposition is appropriately selected depending on the pressure in the vacuum chamber and the input power, but in order to obtain a dense film, a gas containing 100% oxygen is preferred.

Silicon oxide films formed by reactive vacuum evaporation are non-stoichiometric oxides with fewer or more oxygen atoms compared to metal atoms, and small amounts of unoxidized metal atoms. It's okay.

X of the obtained SiOX film greatly influences gas barrier properties such as light transmittance, oxygen transmittance, and water vapor transmittance, and X=1.
When X is less than 0, the light transmittance is low, and when X is over 2.0, no gas barrier properties are obtained at all. Preferably X=1.
The range is from 0 to 2.0, more preferably from 1.5 to 2.0, most preferably from 1.7 to 1.9.

The silicon oxide film contains elements other than the metal atoms mentioned above, such as Fe, 5bXC, MoXW, and Cu.

A trace amount of Zr, Ni, etc. may be included.

The thickness of the silicon oxide layer is preferably in the range of 200 to 3,000 thick in terms of gas barrier properties and flexibility. If the film thickness is too thin, the gas barrier properties will be poor; if the film thickness is less than 200, the gas barrier property, especially the oxygen barrier property, will be insufficient; if the film thickness is too thick, the flexibility will be poor, and if the film thickness exceeds 3,000, it will be prone to bending, etc. Cracks and peeling are more likely to occur. More preferably, it is 500 to 200 OA, and most preferably 700 to 1,300 people.

[Applications] The gas barrier film obtained by the present invention can be used in foods, pharmaceuticals,
It can be widely used as a packaging material for electronic parts, mechanical parts, etc.

[Effects] According to the method for producing a transparent gas barrier film of the present invention,
It has the effect of producing transparent films with good gas barrier properties continuously for long periods of time, stably, with good uniformity, and at high speed and low cost.

[Example code] Examples will be described below.

The following method was used to measure the characteristics in the present invention.

(a) Light transmittance Spectral light transmittance was measured using a manufacturing method band recording spectrophotometer model 323 manufactured by Hitachi, Ltd., and the transmittance at a wavelength of 550 nm was defined as the light transmittance.

(Port 5 Water vapor permeability Measured using a water vapor permeability measuring device W825 manufactured by Honeywell Co., Ltd. under the conditions of 40° C. and 100% RH.

(c) Oxygen permeability Measured according to ASTM D-3985 using an oxygen permeability measuring device 0X-TRANloo manufactured by Modern Control Co., Ltd. under the conditions of 20° CO % RH.

(d) ESCA analysis The silicon oxide film was analyzed using ESCA750 manufactured by Shimadzu Corporation, and the value of X of Sin was calculated from the binding energy of the spectrum.

In the example, an axially stretched polyethylene terephthalate film (thickness 12
μm) as a substrate, and a silicon oxide film was formed thereon by reactive vacuum deposition.

Vacuum deposition is done using a carbon crucible (Nippon Carbon Ceram Co., Ltd.)
After filling a granular silicon metal piece (purity 99.99%) into a granular silicon metal piece (using product number EGF-263) and evacuating it to 1 x 1 oz Torr using an electron beam heating type vacuum evaporator, the silicon was heated and melted using an electron beam. A suitable amount of oxygen gas was introduced from near the substrate to form a silicon oxide film with a thickness of 1000 Å on the substrate. This transparent gas barrier film is referred to as Example 1.

Comparative Example 1 A magnesia crucible was used in place of the carbon crucible in Example 1, and reactive vapor deposition was carried out in the same manner, but bumping occurred before the metal silicon in the crucible was sufficiently melted, causing oxidation onto the plastic film. However, it was not possible to form a silicon film.

Comparative Example 2 In place of the metallic silicon in Example 1, -silicon oxide was used as a raw material, and reactive vapor deposition was performed in the same manner.

-Silicon oxide evaporates by sublimation only in areas directly hit by the electron beam, and a silicon oxide film is only formed on the moving plastic film at the initial stage of evaporation.
A uniform silicon oxide film in the longitudinal direction could not be obtained.

Comparative Example 3 Reactive vapor deposition was performed in the same manner as in Example 1, using silicon dioxide as a raw material instead of metallic silicon.

Silicon dioxide melted only where it was hit by the electron beam, and the silicon oxide film was thick at the beginning of the deposition process and became thinner over time. Comparative Example 3 is a sample obtained after the initial stage of vapor deposition and after a lapse of time.

Table 1 shows the evaluation results of the characteristics of Example 1 and Comparative Examples 1 to 3.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a reactive vacuum deposition apparatus for carrying out the manufacturing method of the present invention. In the figure, 1: Vacuum container 2: Film unwinding shaft 3: Cooling drum 4: Film winding shaft 5 Niblast film 6: Evaporator 7: Crucible 8: Gas outlet 9: Gas flow rate control device 10: Oxygen gas cylinder are shown respectively.

Claims (1)

[Claims] (1) SiO_X (X=1.0
A method for producing a transparent gas barrier film, comprising providing a silicon oxide film represented by ~2.0). (2) The method for producing a transparent gas barrier film according to claim (1), characterized in that reactive vapor deposition is performed while introducing a mixed gas containing oxygen into a vacuum system.