JP2745584B2 - Method for producing transparent barrier film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a barrier film in which a silicon oxide thin film is formed on a transparent polymer base material, and is excellent in gas barrier properties, moisture proof properties, and transparency, particularly for pharmaceuticals. The present invention relates to a transparent barrier film used for food packaging materials and the like, and a method for producing the same.

<Prior art and its problems> In the field of packaging of pharmaceuticals, foods, etc., various physical properties are required for materials used for packaging in order to enhance the protection of contents, and these required physical properties are increasingly high. Is becoming more desirable.

In particular, in the protection of contents, oxygen barrier properties and moisture proof properties are indispensable items for packaging materials from the viewpoint of deterioration of the contents and prevention of oxidation, and it is common to provide these barrier properties today. And packaging materials are being designed from this viewpoint.

In addition, recent advances in thin film technology have been remarkable, and technologies for continuously forming thin films of metals, metal oxides, and the like on polymer films that do not have heat resistance and are flexible include devices and methods. It is actively performed from both sides.

On the other hand, a functional film in which several metal oxide thin films are provided on a polymer film in order to provide a function of gas barrier and moisture resistance using such a technique has been proposed, and some of them have been put on the market. .

For example, silicon oxide and aluminum oxide deposited films are disclosed in JP-B-53-12953 and JP-A-62-179935.

However, each of the above-mentioned vapor-deposited films has a problem, and particularly in the case of silicon oxide, it tends to turn brown, and the cause is considered to be largely related to the composition of the vapor-deposited film.

This vapor deposition film composition has a slight change in vacuum degree during vapor deposition,
The deposition processing conditions, such as the residual oxygen partial pressure and the type of the deposition material, have a very large effect, and as a result, the transparency obtained as a function varies widely, leaving a problem at the practical stage.

<Problems to be Solved by the Invention> The present invention solves the above-mentioned conventional drawbacks, and an object of the present invention is to specify a component composition of a silicon oxide thin film to improve gas barrier properties and moisture-proof properties. An object of the present invention is to provide a barrier film which is kept extremely stable and has excellent transparency, and a method for producing the barrier film.

<Means for Solving the Problems> The present invention relates to a method for forming substantially SiO, Si ₂ O ₃ , Si on a polymer film.
This is a transparent barrier film provided with a silicon oxide vapor-deposited film made of a mixed system of O ₂ .

Further, the present invention is a method for producing a transparent barrier film in which silicon oxide is vacuum-deposited on a polymer film while assisting oxygen.

Here, as means for assisting oxygen, reactivity is increased by generating oxygen plasma obtained by introducing oxygen gas or increasing oxygen concentration on the film by an ion beam.

 This will be specifically described below.

First, using the apparatus shown in FIG. 1, a continuous roll is fed from an unwinding roll (8) of a polymer film such as polycarbonate, polyethylene terephthalate, polyamide, or polyethylene in a vacuum system of 10 ^-4 to 10 ^-5 Torr or less. This polymer film passes through a dancer roll (5) and an esspander roll (6), and is cooled at a cooling roll (9) at a position of a silicon oxide molecule evaporated from a vapor deposition material (500) while being cooled. (200) was converted to the high-purity gas (7
00) is supplied into the vacuum chamber by a mass controller (600) and a 13.56 MHz high frequency power supply (40
0), matching box (300) high frequency coil (201)
Is formed, an oxygen plasma state is generated, and a film is formed while assisting the oxygen plasma.

Then, the vapor-deposited polymer film is continuously wound by a winding roll (3) via an expander roll (6) and a dancer roll (5).

The high frequency power supply (400) is not limited to 13.56 MHz, but may be a microwave utilizing 2450 MHz.

Another method is to deposit silicon or silicon oxide on a polymer film by a vacuum deposition method using ordinary heating methods such as resistance heating, induction heating, and electron beam heating, and then deposit the deposited film at 70 ° C. or higher. And a method of performing heat treatment of hot water, steam, or the like at a temperature equal to or lower than the thermal deformation temperature of the polymer film.

Here, the silicon oxide formed on the polymer film is:
It is composed of a mixed system of SiO, Si ₂ O ₃ and SiO ₂ or a mixed system partially containing hydroxide.

The thickness of the silicon oxide thin film formed on the transparent polymer film of the present invention is 300 to 3000 °, preferably 700 to 1500 °. If the thickness is less than 300 mm, functions such as gas barrier properties are not sufficient.If the thickness is more than 3000 mm, the flexibility of the plastic film is impaired because the film thickness is too large, and cracks are generated in the film, resulting in gas barrier properties. Variation and deterioration.

When the transparent barrier film is used as a packaging material, it may be a laminated material having a heat-sealable resin layer on the silicon oxide side.

The heat-sealing resin layer is a commonly used polyolefin such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer. The laminating method may be lamination of a film via an adhesive, or extrusion coating. May be laminated.

<Function> In the case of silicon oxide, the metal oxide film of the film of the present invention is formed of a mixed system of SiO, Si ₂ O ₃ and SiO ₂ or a mixed system containing a part of hydroxide, Si, Si ₂ O It is a barrier film having excellent transparency because it does not contain a lower oxide of

This is because, by treating the film with oxygen and water vapor, the oxidation is three-dimensionally promoted, the apparent denseness of the film is improved, and the oxygen molecules and water vapor molecules of about 2.4 mm High barrier properties against

On the other hand, if a metal component or a lower oxide component is contained, sufficient denseness as a whole film cannot be obtained, and as a result, the barrier properties against oxygen and water vapor partially differ, and as a result, the barrier properties are deteriorated. It has been lowered.

<Example 1> Using the vapor deposition device shown in FIG.
μ polyethylene terephthalate film,
In addition, silicon monoxide was added as a deposition material, and the inside of the tank was 9 × 10 ^-6.
Exhausted to Torr.

Next, a high-purity gas is introduced while being adjusted with a mass flow controller, and high-frequency power is applied, and while creating an oxygen plasma atmosphere, silicon monoxide is evaporated by electron beam heating to form a vapor deposition film having a thickness of 1000 mm on the film. The film was continuously formed such that

(Deposition conditions) High frequency power (13.56 MHz) 1Kw Vacuum degree Controlled by oxygen gas to 5 × 10 ^-5 Torr Deposition rate 60Å / sec (monitored by crystal oscillation type monitor) Oxygen permeation amount of obtained film, water vapor The amount of transmission
It was as follows.

Oxygen permeability of ^{1.5cc / m 2 · 24hrs · atm} (25 ℃, 100% RH) moisture vapor permeability of 2.0g / m ² · 24hrs also using a spectrophotometer to measure the transmittance at a wavelength of 700~400nm Was evaluated for its transparency. As shown in the graph of FIG. 3, the result showed extremely high transparency in the visible region.

In addition, X-ray photoelectron spectroscopy (XPS)
Take the narrow spectrum of Si ₂ p was used to measure the components of Si ₂ p. The results are shown in the graph of FIG.

As a result, it was found that the film was formed of SiO, Si ₂ O ₃ , and SiO ₂ components.

<Comparative Example 1> Vapor deposition was performed under the same conditions as in Example 1 without introducing oxygen gas to obtain a film in which a silicon oxide film was similarly formed.

Then, in the same manner as in Example 1, the oxygen permeation amount, the water vapor permeation amount, the transparency, and the components of the film formation were evaluated.

Oxygen permeability of ^{1.6cc / m 2 · 24hrs · atm} (25 ℃, 100% RH) moisture vapor permeability of 1.9g / m ² · 24hrs transparency, as it is apparent slightly brownish from the graph of Figure 5, exemplary Compared with Example 1, the transparency in the visible region was inferior.

In addition, the components of the film formation contained components of Si and Si ₂ O, as is clear from the graph of FIG.

<Example 2> Using the same materials as in Example 1, the inside of the tank was evacuated to 9 × 10 ^-6 Torr, high-purity gas was introduced while adjusting with a mass flow controller, and a polymer film was used as an oxygen ion beam. The silicon oxide was vapor-deposited by electron beam heating while being applied to the substrate, and was continuously formed on the film so that the vapor-deposited film thickness became 1000 °.

(Evaporation conditions) High frequency power (13.56MHz) 1Kw Ion source output 300V 30mA Ion current density 20μA / cm ² Vacuum chamber pressure 5.2 × 10 ^-5 Torr Evaporation rate 60Å / sec (monitored by crystal oscillation type monitor) When observing the surface shape by SEM photograph, the deposited film assisted by the ion source was
It was denser than that of a deposited film without assist.

The oxygen transmission rate is 1.2cc / m ² · 24hrs · atm (25 ° C, 1
00% RH), and the water vapor transmission rate was 1.8 g / m ² · 24 hrs.

<Effect> As described above, as the thin film composition of silicon oxide on the transparent polymer film, Si, Si ₂ O component is completely converted to SiO, Si ₂ O ₃ , SiO ₂ , Si
By oxidizing (OH) ₃ etc., the conventional oxygen barrier,
The transparency was extremely improved while satisfying the moisture-proof property.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of an apparatus for obtaining a film or a method for carrying out the method of the present invention, FIG. 2 is an explanatory view showing an evaporation source portion of FIG. 1, and FIG. FIG. 4 is a graph showing the measurement results of the components of the vapor deposition formed in Example 1, and FIG. 5 is a graph showing Comparative Example 1.
FIG. 6 is a graph showing the measurement results of the components for vapor deposition of Comparative Example 1;
DESCRIPTION OF SYMBOLS 1 ... Polymer film, 2 ... In a vacuum system 3 ... Winding roll, 4 ... Control roll 5 ... Dancer roll, 6 ... Expander roll 8 ... Unwind roll, 9 ... Cooling roll 10 ... ... Evaporation source, 11 ... Evaporation source power 200 ... Silicon oxide molecule, 201 ... High frequency coil 300 ... Matching box, 400 ... High frequency power supply 500 ... Evaporation material, 600 ... Mass flow controller 700 ... Oxygen gas

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-283136 (JP, A) JP-A-2-34328 (JP, A) JP-A-63-111167 (JP, A) JP-A-58-58 194735 (JP, A)

Claims (1)

(57) [Claims] 1. A method for producing a transparent barrier film, wherein silicon oxide is vacuum-deposited on a polymer film in a vacuum system while generating oxygen plasma or assisting oxygen by an ion beam.