JPS62103359A - Manufacture of transparent film of interrupting gas - Google Patents

Abstract

PURPOSE:To uniformly obtain transparent film having a good interruption property for gas at a high speed, by carrying out vapor deposition while maintaining the ratio of average Al vapor deposition quantity to introduced gaseous oxygen quantity per unit time to a specified range, at forming aluminum oxide layer on a plastic film in a vacuum vessel. CONSTITUTION:At coiling the plastic film 5 set in the vacuum vessel 1 to a shaft 4 for coiling the film 5 while running it from a shaft 2 for rewinding the film 5 along a cooling drum 3, high purity Al is vaporized from crucible in a vaporizer 6 connected to heating electric source. Gaseous oxygen is supplied to a range surrounded with a mask 7 from a gas blowing hole 8 through a gas flow rate controller 9 from a gas bomb 10. In this time, aluminum oxide is vapor deposited on the film 5 while maintaining the ratio of the vaporized quantity A(mol/min) to the introduced quantity B(mol/min) to 0.2<=B/A<0.75.

Description

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

More specifically, the present invention relates to a method for producing a transparent gas barrier film comprising forming an aluminum oxide layer on a plastic film.

[Prior art] Conventionally, as a transparent gas barrier film, silicon oxide was deposited on a plastic film (Japanese Patent Publication No. 53-12).
953> or vapor-deposited aluminum oxide (Japanese Unexamined Patent Publication No. 5
8-217344> is known.

For vapor deposition of metal oxides such as silicon oxide and aluminum oxide, the aforementioned Japanese Patent Publication No. 53-12953 and Japanese Patent Application Laid-open No. 58-217
The most common method is to heat and evaporate the metal oxide itself, as in No. 344, but metal oxides generally have low vapor pressure, require high temperatures for evaporation, and have a low evaporation rate.

As a method for improving this, a reactive vacuum evaporation method is known in which metallic aluminum is heated and evaporated in an atmosphere containing an excessive amount of oxygen gas to form aluminum oxide on a substrate. In this case, as shown by the reaction formula 41+302→2Aα203, an excess of oxygen gas of 0.75 times or more in molar ratio is introduced so that the evaporated metal aluminum is oxidized and forms aluminum oxide. It was customary for them to be supplied.

[Problems to be Solved by the Invention] ``However, the following problems arose in the vapor deposition of aluminum oxide by such a conventional reactive vapor deposition method. That is, when the evaporation rate of aluminum changes, the pressure during evaporation changes significantly, causing problems such as changes in the deposition rate, gas barrier properties, and optical properties of the film. Moreover, this phenomenon becomes more pronounced as the evaporation rate of aluminum becomes faster and the width of the plastic film is wider, and has become an extremely serious obstacle in producing transparent gas barrier films on an industrial scale.

The object of the present invention is to avoid the above-mentioned drawbacks, that is, even if the evaporation rate of aluminum changes, there is almost no pressure fluctuation in the evaporation atmosphere, so that the deposition rate and gas barrier properties of the film are improved in the width and length directions. An object of the present invention is to provide a method for producing a transparent gas barrier film that is uniform and highly transparent.

[Means for Solving the Problems] That is, the present invention heats and evaporates aluminum while introducing oxygen into a vacuum chamber, forms a layer of aluminum oxide on a plastic film substrate, and creates a transparent gas barrier. In the method for producing a plastic film, the ratio (B/A) of the average amount of aluminum evaporated per unit time A [mol 7 minutes] to the oxygen gas conductor foot B per unit time [mol 7 minutes] is set to 0. This is necessary in the I!A method of producing a transparent gas barrier film, which is characterized in that vapor deposition is carried out while maintaining 2≦B/A<0.75.

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

FIG. 1 is a schematic diagram of a reactive vacuum deposition apparatus showing one embodiment of the present invention.

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

At the same time, aluminum is evaporated from the crucible in the evaporator 6 connected to the heating power source, and oxygen gas is supplied from the oxygen cylinder 10 to the area surrounded by the mask 7 through the gas flow controller 9 and the gas outlet 8. Supplied. The evaporated aluminum and Mi gas react, and the plastic film 5
Aluminum oxide is produced on the surface of. Aluminum oxide in the present invention refers to no, Af1202 and A0
203 is shown, but 80,203 is preferable. Aluminum oxide may contain minute metals or other metal oxides.

As a method for heating and evaporating aluminum, methods such as resistance heating, high frequency induction heating, electron beam heating, and reso beam heating are used. Less contamination with impurities, and
High-frequency induction heating and electron beam heating are preferred in that high-speed vapor deposition can be performed over a large area.

As aluminum, it is preferable to use aluminum with few impurities and a purity of 99% or more, preferably 99.5% or more.

The amount of aluminum evaporated during steaming can be measured by measuring the water temperature (by measuring the amount of aluminum in the crucible (
The difference between the amount of aluminum remaining after evaporation (mol) and the amount of aluminum remaining after evaporation (mol) is
It can be expressed as the average aluminum evaporation MA per unit time divided by the deposition time (minutes) [mol 7 minutes], and is defined by this value in the present invention. One mole of aluminum weighs 26.9815q.

The oxygen gas introduction m is controlled by a gas flow rate control device. The amount of oxygen gas introduced per unit time is calculated as the amount of oxygen gas introduced per unit time B [mol 7
minutes].

One mole of oxygen gas has a volume of 22.420 under standard conditions (1 atmosphere, 0°C).

In order to equalize the amount of aluminum oxide deposited (=J) and the gas barrier properties of the film in the longitudinal direction, it is important to keep the gas pressure constant during vapor deposition over a long period of time. The ratio of the average aluminum evaporation mA [mole 7 minutes] to the oxygen gas introduction amount B [mole 7 minutes 1 (B/A>) per unit time was evaporated while maintaining 0.2≦B/A<0.75. It is necessary to do the following.

The evaporated aluminum is converted into a total mW of aluminum (Ag2
In order to react with O3), use the reaction formula 4A+302=2
As shown in AQ203, it is necessary to introduce oxygen gas in a molar ratio of at least 0.75 times that of aluminum, but if oxygen gas is introduced in a molar ratio of 0.75 times or more, the evaporation rate of minute aluminum will decrease. In response to fluctuations, large pressure fluctuations occur due to unreacted oxygen gas, resulting in large fluctuations in the deposited film thickness and gas barrier properties.

If B/Ab'io is less than 2, the film tends to lack transparency, and if the amount of oxygen gas introduced is slightly changed, an aluminum oxide layer with reduced transparency will be formed, and the packaging material It is not preferred as a manufacturing method.

When B/A is 0.2 or more and less than 0.75, a transparent gas barrier film with high transparency and uniform gas barrier properties in the longitudinal direction can be produced. A more preferable range is 0.3 or more
．． Stay below 7.

The reason why a highly transparent aluminum oxide film can be formed even if the oxygen introduction W (B) is less than 0.75 times the aluminum evaporation ff1 (A>) is as follows. The evaporated aluminum adheres upward with a constant film thickness distribution depending on the shape of the evaporator.Generally, 10-60% of the evaporated aluminum adheres to the plastic film, and the rest is deposited in the mask 7 or vacuum vessel. 1. On the other hand, since the introduced oxygen gas is supplied near the base surrounded by the mask 7, most of it reacts with aluminum around this area and becomes chemical aluminum, which is outside the range of the mask 7. It diffuses only a small amount.

Therefore, in order to form an aluminum oxide film only on the substrate, it is sufficient to supply oxygen gas at a molar ratio of at least 0.2 times the amount of aluminum evaporated. Even if the oxygen gas decreases, unreacted oxygen gas reacts with aluminum deposited around the mask and on the inner wall of the vacuum chamber, thereby controlling pressure fluctuations within the vacuum system. As a result,
There is little pressure change in the vacuum chamber, so the gas barrier properties of the aluminum oxide layer are uniform over the length of the film.

The plastic film used in the present invention is not particularly limited, but typical examples include the following.

Polyolefins such as polyethylene, polypropylene, and polybutene, polyesters such as polyethylene terephthalate, polybutylene ethylene terephthalate-1~, polyethylene-2,6-naphthalate-1~, nylon 6, and Nylon 1
2 and other polyamides, polyvinyl chloride, polyvinylidene chloride, ethylene acetate/vinyl copolymer, polystyrene,
Polycarbonate 1-, polyacryloni-1-lyl, polysulfone, polyphenylene oxylide, aromatic polyamide, polyimide, polyamideimide, cellulose, cellulose acetate, etc., copolymers thereof, and copolymers with other precipitates. It may be a combination. These plastic films may be unstretched, -axially stretched, or biaxially stretched, but biaxially stretched ones are preferred from the viewpoint of dimensional stability (shallow area characteristics and stability of gas barrier properties). Known additives such as antistatic agents, anti-blurring agents, lubricants, anti-coloring agents, ultraviolet absorbers, plasticizers, colorants, etc. may be added to the plastic film.

The plastic of the present invention is preferably transparent,
It is desirable that the total light transmittance in white light is at least 40% or more, preferably 60% or more, more preferably 70% or more, and most preferably 80% or more. Known additives such as colorants are desirably added to an extent that does not impair this range. In addition, prior to the formation of aluminum oxide, the plastic film may be subjected to known surface treatments such as corona discharge treatment, fire treatment, plasma treatment, glow discharge treatment, surface roughening treatment, or anchoring treatment of organic or inorganic materials or mixtures thereof. 1 to processing may be performed.

The transparent gas barrier film according to the present invention has excellent barrier properties against oxygen and water vapor, and is highly transparent, so it can prevent the contents from deteriorating and has good transparency. It can be used as packaging material for products, plastic parts, etc.

[Function] According to the method for producing a transparent gas barrier film based on the present invention, a transparent gas barrier film with high gas barrier properties and good uniformity in the longitudinal direction can be produced on an industrial scale that requires wide-width and high-speed vapor deposition. 1q of sexual film is collected.

Furthermore, since the amount of oxygen gas introduced is small, the pressure during vapor deposition is low, the mean free path of aluminum is lengthened, and the deposition yield is also improved.

This will be explained below using examples.

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

(a) Oxygen permeability measurement device (Sedancon 1 to Rolls, 0X-TRANlo) in accordance with ASTM D-3985.
o).

(b) Light transmittance integrating sphere type haze meter (manufactured by Nippon Seimitsu Kogaku, 5EP-H-
3), the transmittance of a white light source (light A specified in JIS Z-8701) was measured.

[Example] Examples include axially stretched polyethylene terephthalate 1 to film (thickness 1
2 μm) was formed into a roll having a width of 200 mm and a length of 6000 m, and was attached to an unwinding shaft of a reactive vapor deposition apparatus shown in FIG.

1 kq (37.06 mol) of aluminum with a purity of 99.9% was charged into an evaporator connected to a high-frequency induction heating power source.
The vacuum vessel was evacuated to 1×10 −41 μl and cooled to −20° C. by passing a refrigerant through a cooling drum.

Next, the evaporator is heated by a high-frequency induction heating power source, and the amount of aluminum evaporated is approximately 10°8Q (0.4Q) per minute.
0 mol), and then the film was adjusted to 100 mol.
m/min, and then the gas flow controller (
Estech Co., Ltd., mass flow controller 5EC51
0>, oxygen gas with a purity of 99.9% is released from the gas outlet at a rate of 4.0 ff per minute (0,1
8 mol), an aluminum oxide film was formed on the film. Ionization vacuum gauge - (ANELVA Co., Ltd. NI-1)
The pressure measured by 0> was approximately 3.times.10@-41 ~-.

Evaporation was continued for 50 minutes while controlling the amount of aluminum evaporated, controlling the oxygen gas flow rate, and recording the pressure, but the device was stopped.
I took out the rolled film.

When I measured the amount of aluminum remaining in the evaporator, it was 46.
0q (17.05 mol). The total amount of aluminum deposited was 540 Cl (20.01 mol), and the average amount of aluminum evaporated per 4 car positions (A>) was 0.4 mol/min.

On the other hand, the introduction of oxygen gas per unit time 1 (B) is ±1
．． O% (7) Accuracy T-4ff/min (0,18-
The temperature was maintained at 100 mph (El/min). The value of B/A is 0.45.

Thereafter, the wound film was sampled every 100 m, and the oxygen transmittance and light transmittance were measured. All light transmittances were 85-88%.

The measurement results of oxygen permeability are shown in FIG. 2 together with the pressure measurements during vapor deposition.

The oxygen permeability of the base film used alone was 15.
8 cc/1T12-24hr, light transmittance is 88%
Met.

Further, the deposited film was analyzed with an ESCA spectrometer (manufactured by Shimadzu Corporation, ESCA750), and it was confirmed that the aluminum oxide was 80.203 from the binding energy of Aa2p spectra 1 to 1.

Example 2 In Example 1, the oxygen gas flow rate was set to 5.6σ/min (0,
Aluminum oxide (80203) was formed on the biaxially oriented polyethylene terephthalate film 1 to 1 to form a transparent gas barrier film in the same manner as in Example 1, except that the amount of polyethylene terephthalate (25 mol/min) was changed to 25 mol/min). The pressure during vapor deposition is 3×10~4
It was in the range of X10'1--. The amount of aluminum remaining in the evaporator after 50 minutes of vapor deposition was 480 Cl.

As a result, the total amount of aluminum evaporated during the deposition time was 520
g (19.27 mol), and the average aluminum evaporation amount (A) per unit time was 0.39 mol/min.

On the other hand, oxygen gas introduction ff1(B) per unit time is ±1
．． It was maintained at 5.6 α/min (0.25 mol/min) with an accuracy of 0%. The value of B/A is 0.64.

Thereafter, the oxygen transmittance and light transmittance were measured every 100 m in the same manner as in Example 1. All light transmittances are 87-88
% was rare. The measurement results of oxygen permeability are shown in FIG. 3 together with the pressure measurements during vapor deposition.

Comparative Example 1 In Example 1, the flow rate of oxygen gas was set to 7Q/min (0,3
Aluminum oxide (80, 203) was formed on the biaxially oriented polyethylene terephthalate film 1 to 1 in the same manner as in Example 1, except that the amount of polyethylene terephthalate was 1 mol/min).

The pressure during vapor deposition is 4X10' to 12x 10-41--
There was a large variation between the two.

The amount of aluminum remaining in the evaporator after 50 minutes of evaporation is 470
It was q. As a result, the total amount of aluminum evaporated during the deposition time was 530 g (19.6 mol), and the average amount of aluminum evaporated per unit time (A) was 0.39 mol/min.

On the other hand, oxygen gas introduction ff1(B) per unit time is ±1
．． It was maintained at 70.7 min (Oy 31 mol/min) with an accuracy of 0%. The value of 8/A is 0.79.

Subsequently, the oxygen transmittance and light transmittance were measured at 100 m in the same manner as in Example 1. All light transmittances are 87-8
It was 8%. The measurement results of the oxygen permeability are shown in FIG. 4 together with the pressure measurements during vapor deposition.

[Effects of the Invention] According to the method for producing a transparent gas barrier film of the present invention, a transparent film with good gas barrier properties can be produced with good uniformity, at high speed, and at a low cost.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of a reactive vapor deposition apparatus for carrying out the present invention, and Figs. 2 to 4 show the oxygen permeability at regular intervals in the length direction of the film and the pressure measurement during vapor deposition, respectively. 2 and 3 are values obtained by the method of the present invention, and FIG. 4 is obtained by the prior art. 1: Vacuum container 2: Film unwinding shaft 3: Cooling drum 4: Film winding shaft 5 Niblast film 6: Evaporator 7: Mask 8: Gas outlet' 9: Gas flow control device 10: Oxygen cylinder

Claims (1)

[Claims] (1) In a method of manufacturing a transparent gas barrier film by heating and evaporating aluminum while introducing oxygen into a vacuum chamber to form a layer of aluminum oxide on a plastic film substrate, the average aluminum evaporation rate per unit time is The vapor deposition is carried out while maintaining the ratio (B/A) between the amount [mol/min] and the amount B [mol/min] of oxygen gas introduced per unit time at 0.2≦B/A<0.75. A method for producing a transparent gas barrier film.