JPH1128783A - Gas barrier film having selective light ray transmission properties - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film, which has transparency, and can shield harmful ultraviolet light and infrared rays by laminating a diamond carbon film, where hydrogen concentration is specific atomic % or lower, and oxygen concentration is specific atomic &or lower, on at least one side of a multi-layer laminated film having selective transmission properties. SOLUTION: A base film is laminated on a Si wafer for placing on a cooling plate 7 in a vacuum vessel 1. When a specified degree of vacuum is reached using a vacuum pump, raw gas is introduced from a gas introducing pipe 8, and high frequency is applied to generate plasma for forming a film. The Si wafer is cooled through the cooling plate 7. Oxygen atoms are appropriately contained in the film to improve transparency without deteriorating gas barrier properties of the film. That is, hydrogen concentration contained in a diamond carbon film acts as a barrier layer against water vapor and oxygen is 50 atomic % or lower, preferably 45 atomic % or lower, and oxygen concentration contained in the film is 2-20 atomic %, preferably 2-15 atomic %.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas barrier film used for food packaging, medicine packaging, electronic component packaging and protection, and the like.

[0002]

2. Description of the Related Art Conventionally, foods, medicines, and the like have been packaged with materials having low gas permeability in order to prevent deterioration due to oxygen, moisture, and the like. In particular, there is an increasing demand for a film having excellent transparency and gas barrier properties as a packaging material for retort foods. As a general method for producing such a film, a method of producing a single-layer film with a gas-barrier resin such as an ethylene vinyl alcohol copolymer or a co-extrusion molding of a gas-barrier resin and a resin having no gas-barrier property is used. Alternatively, there is a method of forming a multilayer film by lamination molding. Also, a method of forming ceramics such as silicon oxide and aluminum oxide and a diamond-like carbon film on a plastic film having no gas barrier property,
There is a method of coating the surface with a gas barrier resin such as vinylidene chloride. Although these transparent gas barrier films have the feature of being able to see the contents, they cannot prevent deterioration of foods, medicines, and the like due to light.

On the other hand, it is known that the gas permeability becomes extremely low by providing an Al metal layer on a plastic film, for example, by vacuum evaporation. This also blocks light, so that alteration can be efficiently suppressed. However, a film provided with an Al metal layer has poor transparency and cannot be used in a microwave oven.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object the purpose of being able to see the contents with transparency and to block harmful ultraviolet rays and infrared rays. An object of the present invention is to provide a film having excellent gas barrier properties.

[0005]

According to the present invention, a diamond-like carbon film having a hydrogen concentration of 50 atomic% or less and an oxygen concentration of 20 atomic% or less is provided on at least one surface of a multilayer laminate film having selective permeability. Are laminated on the gas barrier film. A resin having a different refractive index from A / B /
A large number such as A / B / A / B... By appropriately determining the thickness and layer configuration of each layer, a film having functions such as selective light transmittance and selective reflectivity can be produced. For the purpose of packaging foods and medicines,
It is necessary to determine the thickness and composition of the layer so as to block ultraviolet and infrared rays.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The resin used for producing a multilayer laminate is not particularly limited as long as it is a resin having thermoplasticity, and it may be a crystalline resin or an amorphous resin. For example, polyolefin, polyester, nylon, polycarbonate, polystyrene, polyacrylate, etc., which are thermoplastic resins conventionally used as molding materials for packaging materials such as daily necessities, miscellaneous goods, foods, tablet medicines and the like can be mentioned.

A specific example of the thermoplastic resin used in the present invention is an α-olefin represented by the general formula CH 2 ＝ CHR (where R represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms). Homopolymers or copolymers, more specifically, polyethylene such as high-density polyethylene, low-density polyethylene, and linear low-density polyethylene;
-Butene copolymer, ethylene / 4-methyl-1-pentene copolymer, ethylene / 1-hexene copolymer, polypropylene, ethylene / propylene copolymer, propylene / 1-butene copolymer, poly-1-butene , 1-butene
4-methyl-1-pentene copolymer, poly-4-methyl-
Examples thereof include 1-pentene and poly-3-methyl-1-butene.

Other thermoplastic resins include cyclic olefin resins such as ethylene / cyclic olefin copolymers, cyclic olefin ring-opening polymers or copolymers, and ethylene / cyclic olefin resins.
Fluorine resin such as vinyl acetate copolymer, ethylene / acrylic acid copolymer or its metal salt, polystyrene, polyvinyl alcohol, polymethyl methacrylate, polymethyl chloride, polyvinylidene chloride, polytetrafluoroethylene, polycarbonate, polyacrylate, polyethylene Examples include terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyether sulfone, polyimide, and polyphenylene oxide.

The above-mentioned thermoplastic resins can be used alone or in combination of two or more. As the thermoplastic resin, AST
It is practically preferable that the low-load heat deformation temperature measured by MD648 is 60 ° C. or more, preferably 70 to 140 ° C.

In order to increase the permissible range of the selective light transmittance, it is preferable that the difference in the refractive index of each resin is large. That is, the difference in the refractive index of each resin is preferably 0.05 or more, more preferably 0.10 or more, and even more preferably 0.15 or more. For example, the refractive indices of polyethylene terephthalate and poly-4-methyl-1-pentene are 1.66 and 1.46, respectively, and a preferable combination because the refractive index difference is 0.2. The refractive indices of polycarbonate and polymethyl methacrylate are 1.58 and 1.49, respectively, and the difference in refractive index is preferably 0.09, which is preferable.

Examples of the method for producing the multilayer laminate include a multilayer T-die molding method, a multilayer inflation molding method, a co-extrusion molding method such as extrusion lamination molding, a wet or dry lamination molding method, a multilayer blow molding method, and the like. Two types of resins having different refractive indices can be laminated by employing a general multilayer laminate molding method such as a two-color molding method, a sandwich molding method, a stamping molding method, and the like. In these forming steps, a base laminate comprising at least two layers of a first layer and a second layer is formed,
Subsequently, in the dividing step, the above-described basic laminate is divided in a plane parallel to the longitudinal direction and perpendicular to the lamination interface, and in the next laminating step, the divided laminated body obtained in the dividing step is heated. A multilayer laminate is manufactured by forming a multilayer molded body by laminating on a plane parallel to the interface.

In the above method, the forming step, the dividing step and the laminating step are repeated one or more times, preferably 2 to 10 times. The multilayer laminate obtained in this way can be subjected to secondary processing such as stretching and rolling to further reduce the thickness of each layer. In order to form a diamond-like carbon film on the surface of the multilayer laminate, the thickness of the multilayer laminate is 0.01 to
Preferably, it is 1 mm.

The diamond-like carbon film referred to in the present invention is:
Amorphous diamond-like carbon, which contains diamond, graphite, and polymer components. This diamond-like carbon film has different properties depending on the mixing ratio of these components, and even a diamond-like carbon film having high hardness does not always function as a gas barrier layer for water vapor, oxygen, and the like.

Conventionally, the film quality of a diamond-like carbon film has been considered using its hydrogen concentration as an index. That is, the lower the hydrogen concentration, the more the film exhibits the properties of diamond,
On the other hand, when the hydrogen concentration increases, the hardness of the film decreases due to the properties of graphite or polymer. However, the gas barrier properties of a diamond-like carbon film do not always correspond to the hardness of the film. Further, since the gas barrier property is considered to be determined by the concentration of sites where the atoms constituting the film are disconnected, it has been considered that the reduction of the hydrogen concentration contributes to the improvement of the gas barrier property.

The present inventor has studied reduction of the hydrogen atom content in the film in order to improve the gas barrier properties of the film, but the transparency of the obtained film was not always preferable. Therefore, when a method for increasing the transparency of the film was examined without increasing the hydrogen concentration in the film, surprisingly, it was surprising that oxygen atoms, which had conventionally been considered to be a cause of deteriorating gas barrier properties, were changed. It has been found that the effect of increasing the transparency can be obtained without appropriately deteriorating the gas barrier properties of the film by appropriately adding it in the film.

That is, the concentration of hydrogen contained in the diamond-like carbon film acting as a barrier layer for water vapor or oxygen of the present invention is 50 atomic% or less, preferably 45 atomic% or less, more preferably 40 atomic% or less. And the concentration of oxygen contained in the film is 2 to 20 atomic%, preferably 2 to 15 atomic%, more preferably 2 to 10 atomic%,
Particularly preferably, it is 2 to 5 atomic%.

In order to form the diamond-like carbon film, a source gas containing carbon and hydrogen is used. Examples of the raw material gas containing carbon and hydrogen include alkane-based gases such as methane, ethane, propane, butane, pentane, and hexane; ethylene, propylene, butene,
Alkene-based gases such as pentene, alkane-based gases such as pentadiene and butadiene; alkyne-based gases such as acetylene and methylacetylene; benzene, toluene,
Aromatic hydrocarbon gases such as xylene, indene, naphthalene, and phenanthrene; cycloalkene gases such as cyclopropane and cyclohexane; alcohol gases such as methanol and ethanol; ketone gases such as acetone and methyl ethyl ketone; And aldehyde gases such as ethanal. The above gases may be used alone or in combination of two or more.

The raw material gas includes a mixed gas of the above-mentioned raw material gas containing carbon and hydrogen and a hydrogen gas; a gas composed of only carbon and oxygen such as carbon monoxide gas and carbon dioxide gas; Mixed gas of carbon monoxide gas,
A mixed gas of a gas composed of only carbon and oxygen such as carbon dioxide gas and hydrogen gas; a mixed gas of carbon monoxide gas, a gas composed of only carbon and oxygen such as carbon dioxide gas, an oxygen gas, and a water vapor No.

Further, examples of the raw material gas include a mixed gas of the above-mentioned raw material gas containing carbon and hydrogen and a rare gas. Examples of the rare gas include helium, argon, neon, and xenon, and these may be used alone or in combination of two or more.

The mixing amount of hydrogen gas, oxygen gas and rare gas in the above mixed gas varies depending on the type of equipment to be used, the type of mixed gas, the film forming pressure conditions, and the like. Therefore, the concentration of hydrogen contained in the formed diamond-like carbon film is 5
0 atomic% or less, more preferably 45 atomic% or less, still more preferably 40% or less, and 2 to 20 atomic% of oxygen atoms, preferably 2 to 15 atomic%, and more preferably 2 to
The conditions are adjusted so as to be 10 atomic%, particularly preferably 2 to 5 atomic%.

As a carbon source, solids of carbon isotopes such as graphite and diamond can also be used, and they are used by being installed in a plasma under an atmosphere of hydrogen gas or a rare gas.

Examples of means for exciting the raw material gas by plasma include: a method of applying a direct current to perform plasma decomposition; a method of applying a high frequency to perform plasma decomposition; a method of performing plasma decomposition by microwave discharge; A method of plasma decomposition; a method of thermal decomposition by heating with a hot filament, and the like. Among these, the method of applying DC plasma is:
If the film-forming substrate is a plastic film which is an insulator, plasma is not generated, which is not preferable. In addition, when the hot filament method is used, the filament must be heated to a high temperature of 500 ° C. or higher, which may not be preferable when the heat resistance of the film-forming substrate is low.
The microwave plasma method and the method of decomposing plasma by electron cyclotron resonance are preferable methods because the film formation speed is high and the film formation temperature is low. Further, a method using high-frequency plasma is preferable in the case of forming a film on a large-area film.

As a method for forming a diamond-like carbon film, there are physical vapor deposition methods such as ion beam sputtering and ion plating, and these methods may be employed.

The thickness of the diamond-like carbon film is determined as necessary. However, if the film thickness is too large, the adhesion to the substrate film is deteriorated, the coated substrate is deformed by film stress, and the transparency is reduced. 0.5 μm or less, more preferably 0.1 μm or less, particularly 0.05 μm
m or less is preferable.

In order to enhance the adhesion between the multilayer laminate and the diamond-like carbon film, if necessary, a cleaning treatment such as cleaning for degreasing and dewatering the substrate surface, and a He surface on the substrate surface in a vacuum vessel. A known process such as a plasma process using an inert gas such as an inert gas or an active gas such as an oxygen gas may be performed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. <Method of Manufacturing Multilayer Laminate> FIG. 1 is a perspective view showing a method of manufacturing a multilayer laminate. In FIG. 1, 1 is a base laminate,
Reference numerals 1a, 1b, 1c, and 1d denote divided laminates, and 2 denotes a multilayer laminate. In the step (1), the basic laminate 1 composed of the first layer A and the second layer B is formed into a film, sheet, or block shape continuously in a heated state, preferably in a molten state, in the longitudinal direction. In order to form the base material body 1 in a molten state from the resin as described above, for example, a method such as co-extrusion molding or co-injection molding can be used. In this step (1), it is preferable that the basic laminate 1 be expanded in the width direction. The base laminate 1 thus formed is supplied to the step (2) continuously in the longitudinal direction inside the forming die.

The basic laminate 1 obtained in the step (1)
Is usually about 100 μm to 50 mm, and the thickness of each layer is preferably about 50 μm to 25 mm. Next, in step (2), the basic laminate 1 in the heated state obtained in step (1) is divided along a plane parallel to the longitudinal direction and perpendicular to the lamination interface. The number of divisions is
Usually, it is about 2 to 6. Further, the basic laminate 1 may be divided into the target number at once, but it is desirable to divide it into multiple stages, preferably two successively, and to divide it into a desired number.

In FIG. 1, the basic laminate 1 is a divided laminate 1
An example in which the image is divided into four parts a, 1b, 1c, and 1d is shown. Specifically, the base laminate 1 supplied from the step (1) is divided into four by being supplied to a channel divided into four in the die. In the step (2), after each of the divided laminated bodies 1a to 1d thus divided is twisted with its longitudinal direction as a rotation axis, the lamination interfaces of the divided laminated bodies are maintained parallel to each other. The direction of the torsion may be any direction around the axis with the longitudinal direction of the divided laminated bodies 1a to 1d as the rotation axis. FIG. 1 shows an example in which all of the divided laminated bodies 1a to 1d are twisted by 90 ° in the same direction. The twisted divided laminates 1a to 1d are supplied to the next step (4) with their respective planes parallel to each other.

In the step (4), the parallel surfaces of the divided laminated bodies 1a to 1d supplied from the step (3) are overlapped, laminated and integrated to form a multilayer laminated body 2. That is, the parallel surfaces of the divided laminated bodies 1a to 1d are closely adhered and integrated in a molten state to form the multilayer laminated body 2.

FIG. 2 shows a preferred embodiment in the step (4). As shown in FIG. 2, in this step (4), the multi-layered laminated body 2 which has been laminated and integrated is turned to the original angle in the twisted state.
Preferably, further twisted to the horizontal direction, the multilayer laminate 2
Can be moved on a roll. In the step (4), the multilayer laminate is moved in a flow path having a taper such that the thickness decreases in the traveling direction and increases in width, or is rolled by a roll.
Thickness reduction processing is performed to reduce the thickness and increase in the width direction as compared to immediately after lamination and integration.

In the present invention, it is preferable that the laminated structure obtained in the final step as described above is used as a laminated body in the step (1), and each of the steps (2) to (4) is repeated at least once. . In this way, the number of layers is sequentially increased, and finally, a multilayer structure having a multilayer structure of several hundreds to tens of thousands of layers can be obtained. For example, in FIG. 1, using the laminated structure 2 as the laminated body 1, the steps (2) to (4) are repeated once, 32 layers are repeated twice, 128 layers are repeated, and 2048 is repeated four times.
A layered structure of layers can be obtained. The multilayer laminate obtained in this manner can be further subjected to secondary processing such as stretching or rolling as necessary, to further reduce the thickness of each layer.

FIGS. 3 and 4 show a particularly preferred embodiment of the method for manufacturing a laminated structure according to the present invention as described above.
Each step is described for a heated multi-layer resin flow passing through a flow path in a die as in FIG. 1, and FIGS. 3 and 4 show schematic plan views and side views of the resin flow. 3 and 4, each flow path point in the die is to the above step (1), from the point to the above step (2), from the point to the above step (3), and from the point to the above step (4). ).

<Method of forming diamond-like carbon film> FIG.
FIG. 1 is a schematic view showing an example of an apparatus for producing a diamond-like carbon film of the present invention. The base film is attached to the Si wafer, placed on the cooling plate 7 in the vacuum vessel 1 and a predetermined vacuum degree is applied by a vacuum pump (not shown). Then, the raw material gas is introduced from the gas introduction pipe 8 and the high frequency is applied. To generate plasma to form a film. The Si wafer is cooled by the cooling plate 7.

The temperature of the substrate film is controlled by a method of circulating a liquid or gas, infrared rays, electric heating, or the like. It is preferable that the temperature is maintained at least below the glass transition point of the substrate film. A liquid circulation system having a large heat capacity is preferred. At this time, the liquid to be circulated may be a liquid heated or cooled to a predetermined temperature, and the liquid to be circulated may be water, ethylene glycol (antifreeze), alcohols. Liquid nitrogen, liquid helium and the like are preferably used.

The application of a DC bias to the substrate is preferable in order to widen the composition range of the source gas that can be used and to improve the film quality. The DC bias value is -500 to 100 V
And more preferably −400 to 10V.
The degree of vacuum in the vacuum vessel 1 is preferably 10 ^-4 Torr or less in order to eliminate the influence of the remaining impurity gas on the film formation. The pressure during film formation is 1 × 10 ^{−3 to} 10 Torr.
Is preferred.

[0036]

EXAMPLE The following resin was used as a thermoplastic resin for producing a multilayer laminate. First layer: intrinsic viscosity 0.90 dl / g, melting point 260 ° C.
Polyethylene terephthalate having a heat distortion temperature of 68 ° C. Second layer: Polymethyl methacrylate having a heat distortion temperature of 95 ° C. A multilayer laminate of 256 layers is prepared using a multilayer laminate manufacturing apparatus, and then stretched to a thickness of about 26 μm. A film was obtained. The flow rate of the resin was adjusted so that the thickness of polyethylene terephthalate and polymethyl methacrylate was 9: 1. The average thickness of each layer was about 180 nm and about 2 nm, respectively.
It was 0 nm.

After attaching this multilayer laminated film to a Si wafer, it was set on a cooling plate 7 in a vacuum vessel 1 shown in FIG. 5, and the pressure in the vacuum vessel was reduced to 1 × 10 ⁻⁵ Torr.
Next, gas is introduced from the introduction pipe 8. Source gas C ₂ H ₂
Is set to 50 sccm, and the pressure in the vacuum vessel 1 is set to 5 × 1
After setting to 0 ^-3 Torr, the frequency is 13.56 MHz,
Film formation was performed for 2 minutes by applying a high-frequency power of 0 W. The thickness of the film determined by observation with a transmission electron microscope was about 0.08 μm. As a result of evaluating the obtained film by Raman spectroscopy, it was confirmed that the film was a diamond-like carbon film. According to the composition of the film determined using Rutherford backscattering, the diamond-like carbon film contained 48 atomic% of hydrogen, Oxygen was contained at 4 atomic%.

The multilayer laminate film on which the diamond-like carbon film was formed was evaluated by the following method, and is shown in Table 1 and FIG. (1) Moisture permeability Using a gas permeability measuring device manufactured by Mocon, 40
The measurement was performed under the conditions of ° C and 90% relative humidity. (2) Oxygen permeability Using a gas permeability measuring device manufactured by Yanaco Co., Ltd., the measurement was performed in an oxygen atmosphere at 23 ° C. (3) Reflectivity Measured using a spectrophotometer UV-365 manufactured by Shimadzu Corporation.

[0039]

[Table 1]

[0040]

The gas barrier film of the present invention transmits visible light, blocks ultraviolet rays and infrared rays, and has extremely low gas permeability. Therefore, the gas barrier film is suitably used for packaging and protecting retort foods, medicines, electronic parts and the like. .

[0041]

[Brief description of the drawings]

FIG. 1 is a perspective view showing a method according to the present invention.

FIG. 2 shows a preferred embodiment in the production step (4) of the multilayer laminate according to the present invention.

FIG. 3 is a schematic plan view of a resin flow in manufacturing a multilayer laminate according to the present invention.

FIG. 4 is a schematic side view of a resin flow in the production of a multilayer laminate according to the present invention.

FIG. 5 is a schematic view showing an apparatus for forming a diamond-like carbon film for producing a gas barrier film according to the present invention.

FIG. 6 is a view showing the result of measuring the reflectance of a film obtained according to an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Basic laminated body 1a, 1b, 1c, 1d Divided laminated body 2 Multilayer laminated body 3 Vacuum container 4 High frequency electrode 5 Base film adhered to Si wafer 6 Matching device 7 High frequency power supply 8 Thermocouple 9 Cooling plate 10 Gas introduction pipe

Claims (3)

[Claims] 1. A diamond-like laminate having a hydrogen concentration of 50 atomic% or less and an oxygen concentration of 2 to 20 atomic% on at least one surface of a laminate comprising two or more light-transmitting resin layers having different refractive indices. Gas barrier film with carbon film. 2. The gas barrier film according to claim 1, wherein the laminate is a multilayer laminate having selective light transmittance. 3. The gas barrier film according to claim 2, wherein the selective light transmittance is excellent in blocking ultraviolet and infrared rays and also excellent in transmitting visible light.