JP2004203023A - High performance barrier film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high performance barrier film as a gas barrier film yielding no delamination by increasing the cohesive force of a PEN/PET co-extrusion film. <P>SOLUTION: Pretreatment using plasma of a reactive ion etching (RIE) mode is applied to at least one surface of a polyethylene naphthalate (PEN)/polyethylene terephthalate (PET) co-extrusion film and a vapor deposition layer consisting of a metal or an inorganic compound of 5-100nm thickness is provided on the treated surface of the co-extrusion film to constitute the high performance barrier film. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a high-performance barrier film as a gas barrier material used in the field of packaging foods, pharmaceuticals, precision electronic components, and the like.

  In recent years, packaging materials used for the packaging of foods, non-food products, pharmaceuticals, etc. have deteriorated oxygen, water vapor, and other contents that pass through the packaging materials in order to suppress the deterioration of the contents and maintain their functions and properties. It is necessary to prevent the influence of the gas to be caused, and it is required to have a gas barrier property or the like for blocking these. Therefore, conventionally, a packaging material using a metal foil such as aluminum which is less affected by temperature and humidity as a gas barrier layer has been generally used.

  However, packaging materials made of metal foil such as aluminum have excellent gas barrier properties without being affected by temperature and humidity, but have the disadvantage that they must be treated as incombustibles when disposed after use. There was a problem.

  Therefore, as a packaging material overcoming these drawbacks, a vapor-deposited film of a metal such as aluminum, a silicon oxide, and an inorganic oxide such as aluminum oxide was formed on a polymer film by forming means such as a vacuum vapor deposition method or a sputtering method. Film is being developed. These vapor-deposited films are known to have gas barrier properties against oxygen, water vapor, and the like, and are considered suitable as packaging materials.

  It is said that the barrier performance of the vapor-deposited film is affected by the barrier properties of the substrate, the denseness of the vapor-deposited layer, and the like. Polyethylene naphthalate (PEN) is suitable as a vapor deposition substrate because it has excellent mechanical suitability and heat resistance, and also has excellent barrier properties of the substrate itself. However, the material cost is high and it is not suitable for packaging applications. is there. However, a PEN / polyethylene terephthalate (PET) co-extruded film having PEN as a skin layer has been put on the market as a method of utilizing the characteristics of PEN and providing an inexpensive base material. Attempts have been made to deposit a vapor deposited layer on this film. However, due to the problem of the compatibility of PEN / PET, the cohesive force at the PEN / PET interface is weak, and sufficient adhesion as a packaging material has not been achieved.

  In order to solve this problem, it is conceivable to improve the interlayer cohesion of PEN / PET by in-line pretreatment using plasma.

  However, in the conventional plasma processing, an electrode for applying a voltage for plasma generation is provided not on the drum side where the base material is located, but on the opposite side. In the case of this apparatus, since the substrate is placed on the anode side, a high self-bias was not obtained, and as a result, a high treatment effect could not be exhibited.

  In order to obtain a high self-bias, a DC discharge method can be used.However, if an attempt is made to obtain a high bias voltage by this method, the mode of the plasma changes from glow to arc, so that a large area uniform processing is performed. Cannot be performed.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a high-performance barrier film as a gas barrier film that does not cause delamination by enhancing the cohesive force of a PEN / PET co-pressed film. And

To achieve the above objectives,
According to the first aspect of the present invention, at least one surface of a polyethylene naphthalate (PEN) / polyethylene terephthalate (PET) co-extruded film is subjected to a pretreatment using plasma in a reactive ion etching (RIE) mode, and A high-performance barrier film characterized in that a vapor-deposited layer made of a metal or an inorganic compound having a thickness of 5 to 100 nm is provided thereon.

  The invention according to claim 2 is characterized in that the pretreatment using the RIE mode plasma is a treatment performed using one kind of gas of argon, nitrogen, oxygen, and hydrogen, or a mixed gas thereof. The high-performance barrier film according to claim 1,

According to a third aspect of the present invention, in the pre-treatment using the plasma in the RIE mode, the self-bias value is 200 V or more and 2000 V or less, and the Ed value defined by Ed = plasma density × processing time is 100 V · s · m. a high performance barrier film according to claim 1, wherein the ^-2 10000 V · s · m ^-2 or less is treatment with low temperature plasma.

  The invention according to claim 4 is the high-performance barrier film according to any one of claims 1 to 3, wherein the metal is aluminum, tin, titanium, or a mixture thereof.

  The invention according to claim 5 is the high-performance barrier film according to any one of claims 1 to 3, wherein the inorganic oxide is aluminum oxide, silicon oxide, or a mixture thereof.

  The invention according to claim 6 is characterized in that the pretreatment and the vapor deposition using the RIE mode plasma are performed in the same film forming machine (in-line film forming machine). It is a high-performance barrier film described in the paragraph.

  The invention according to claim 7 is a composite having, as a component, at least one or more of a hydroxyl group-containing polymer compound, a metal alkoxide and / or a hydrolyzate and / or a polymer thereof, on the vapor deposition layer made of the metal or the inorganic compound. The high performance barrier film according to any one of claims 1 to 6, further comprising a coating.

  The invention according to claim 8 is characterized in that the hydroxyl group-containing polymer compound has at least one of polyvinyl alcohol or poly (vinyl alcohol-co-ethylene), cellulose, and starch as components. Is a high-performance vapor deposition barrier film.

  The invention according to claim 9 is the high-performance barrier film according to claim 7 or 8, wherein the metal alkoxide is a silane alkoxide or a silane coupling agent.

  According to the present invention, by performing a pre-treatment by RIE on a PEN / PET co-extruded film, the interlayer cohesion of PEN / PET is increased, and a metal or inorganic oxide deposited layer is provided on PEN to cause delamination. It has become possible to provide a high-performance barrier film having high barrier performance.

Further, the high-performance barrier film of the present invention can provide a packaging material having a wide practical range used for packaging non-food products such as foods, pharmaceuticals, and electronic members.

  Hereinafter, an embodiment of the present invention will be described.

  FIG. 1 is a sectional view showing an example of the high-performance barrier film of the present invention. A structure in which a vapor-deposited layer 2 made of a metal or an inorganic oxide and a composite coating layer 3 are formed on the surface of a PEN / PET co-extruded film 1 that has been subjected to pretreatment by reactive ion etching (RIE) using plasma. is there. The vapor-deposited layer 2 and the composite coating layer 3 made of a metal or an inorganic oxide may be formed on both sides of the substrate, or may be multi-layered.

  In the PEN / PET co-extruded film 1 used in the present invention, the thickness of the PEN layer is preferably as thin as possible in view of cost, but about 1 μm to 3 μm is appropriate in consideration of film formability. Further, on the surface of the substrate opposite to the surface on which the deposition layer is provided, various well-known additives and stabilizers such as an antistatic agent, an ultraviolet inhibitor, a plasticizer, and a lubricant may be used.

  Although the total thickness of the co-extruded film 1 is not particularly limited, it is practically preferably in the range of 3 to 200 μm, particularly preferably 6 to 30 μm in consideration of workability.

  In order to enhance the interlayer cohesion of PEN / PET, it is effective to perform pretreatment by reactive ion etching (RIE) using plasma on the surface. By performing the RIE process, the generated radicals and ions reach between the PEN / PET layers and increase the cohesion of the PEN / PET layers.

  Argon, oxygen, nitrogen, and hydrogen can be used as gas species for performing the pretreatment by RIE. These gases may be used alone or as a mixture of two or more gases. Further, the processing may be continuously performed using two processing units.

The processing conditions indicated by the processing speed, the energy level, and the like should be appropriately set according to the type of the base material, the application, the characteristics of the discharge device, and the like. However, the self-bias value of the plasma 200V or 2000V or less, Ed = Ed values defined in plasma density × processing time is necessary to below 100V · s · m ^-2 higher 10000V · s · m ^-2 Even if the value is slightly lower than this, a certain degree of adhesion is exhibited, but the superiority is lower than that of the untreated product. On the other hand, if the value is too high, a strong treatment is applied too much, and the surface of the base material is deteriorated, which causes a decrease in adhesion. Regarding the plasma gas and its mixing ratio, the flow rate differs between the introduced and effective components depending on the pump performance and the mounting position, etc., and should be appropriately set according to the application, substrate, and device characteristics.

  Examples of the metal forming the vapor deposition layer made of a metal used in the present invention include aluminum, tin, titanium, and a mixture thereof.

  In addition, examples of the inorganic oxide that forms the vapor-deposited layer made of the inorganic oxide used in the present invention include aluminum oxide, silicon oxide, and a mixture thereof.

The optimum conditions for the thickness of the vapor-deposited layer vary depending on the type and composition of the metal or inorganic compound used, but generally the thickness is preferably in the range of 5 to 300 nm, and the value is appropriately selected. However, if the film thickness is less than 5 nm, a uniform film may not be obtained or the film thickness may not be sufficient, and the function as a gas barrier material may not be sufficiently achieved. On the other hand, if the thickness exceeds 300 nm, flexibility cannot be maintained in the thin film, and there is a problem that the thin film may be cracked by external factors such as bending and pulling after film formation.
More preferably, it is within the range of 10 to 150 nm.

  There are various methods for forming a vapor-deposited layer made of a metal or an inorganic oxide on a co-extruded film substrate, and it can be formed by a normal vacuum vapor-deposition method. Further, other thin film forming methods such as a sputtering method, an ion plating method, and a plasma vapor deposition method (CVD) can also be used. However, in consideration of productivity, the vacuum deposition method is currently the most excellent. It is preferable to use any one of the electron beam heating method, the resistance heating method, and the induction heating method as the heating means of the vacuum evaporation method. Is more preferred. In addition, in order to improve the adhesion between the deposition layer and the base material and the denseness of the deposition layer, deposition can be performed using a plasma assist method or an ion beam assist method.

  Next, the composite coating layer 3 will be described. The composite coating layer is a coating layer having gas barrier properties and is formed using a coating agent mainly composed of an aqueous solution containing a water-soluble polymer and at least one metal alkoxide or a hydrolyzate thereof, or a mixed solution of water / alcohol. You. For example, a solution is obtained by dissolving a water-soluble polymer in an aqueous (water or water / alcohol mixture) solvent and mixing the metal alkoxide directly or in advance with a treatment such as hydrolysis. This solution is coated on a vapor deposition layer made of a metal or an inorganic oxide, and then dried by heating. Each component contained in the coating agent will be described in more detail.

  Examples of the water-soluble polymer used for the coating agent in the present invention include polyvinyl alcohol, polyvinylpyrrolidone, starch, methylcellulose, carboxymethylcellulose, and sodium alginate. In particular, when polyvinyl alcohol (hereinafter, abbreviated as PVA) is used for the coating agent of the present invention, the gas barrier property is most excellent, which is preferable. The PVA referred to here is generally obtained by saponifying polyvinyl acetate. As the PVA, for example, complete PVA in which only a few% of acetate groups remain from so-called partially saponified PVA in which acetic acid groups remain in several tens%, and other materials may be used. .

The metal alkoxide is a compound represented by the general formula, M (OR) n (M: metal such as Si, Ti, Al, Zr, R: alkyl group such as CH ₃ , C ₂ H ₅ ). Specifically, tetraethoxysilane [Si (OC ₂ H _{5) 4],} triisopropoxyaluminum _{[Al (O-2'-C 3} H 7) 3 ], and the like, among which tetraethoxysilane, triisopropoxy Aluminum is preferable since it is relatively stable in an aqueous solvent after hydrolysis.

  Known additives such as an isocyanate compound, a silane coupling agent, or a dispersant, a stabilizer, a viscosity modifier, and a coloring agent can be added to the solution as needed, as long as the gas barrier properties are not impaired. is there.

  As a method of applying the coating agent, a conventionally known method such as a commonly used dipping method, roll coating method, screen printing method, spray method, gravure printing method, or the like can be used.

  The thickness of the composite coating layer 3 varies depending on the type of the coating agent, the processing machine and the processing conditions, and is not particularly limited. However, when the thickness after drying is 0.01 μm or less, it is not preferable because a uniform coating film cannot be obtained and sufficient gas barrier properties cannot be obtained. On the other hand, if the thickness exceeds 50 μm, cracks may easily occur in the film, which may cause a problem. It is preferably in the range of 0.01 to 50 μm, and more preferably in the range of 0.1 to 10 μm.

A printing layer, an intervening film, a sealant layer, and the like can be laminated on the composite coating layer 3 to form a packaging material.

  The intervening film is provided to increase the breaking strength or piercing strength at the time of the bag-shaped packaging material, and is generally a biaxially stretched nylon film, a biaxially stretched polyethylene terephthalate film, in terms of mechanical strength and thermal stability. It must be a type selected from biaxially oriented polypropylene films. The thickness is determined according to the material and the required quality, but is generally in the range of 10 to 30 μm.

  Furthermore, the sealant layer is provided as an adhesive layer when forming a bag-like package or the like. For example, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer and their metals A resin such as a crosslinked product is used. The thickness is determined according to the purpose, but is generally in the range of 15 to 200 μm.

  A printing layer, an intervening film, a sealant layer, and the like can be laminated on the opposite surface of the co-extruded film substrate as needed.

Hereinafter, Examples of the high performance barrier film of the present invention will be specifically described. Note that the present invention is not limited to these examples.
<Example 1>
One side of a PEN / PET co-extruded film (PEN skin layer 1 μm) having a thickness of 12 μm as a base material was subjected to pretreatment by reactive ion etching (RIE) using plasma. At this time, a high frequency power supply having a frequency of 13.56 MHz was used for the electrodes, and argon was used for the processing gas. On this, aluminum oxide was formed into a film with a thickness of 20 nm by reactive evaporation using an electron beam heating method to form an evaporation barrier film.
<Example 2>
A vapor deposition barrier film was prepared in the same manner as in Example 1 except that a mixed gas of argon / oxygen was used as a processing gas.
<Example 3>
An evaporation barrier film was prepared in the same manner as in Example 1, except that a mixed gas of argon / nitrogen was used as a processing gas.
<Example 4>
The deposition method was the same as in Example 1, except that pretreatment by RIE was performed using two plasma processing devices, treatment by argon was performed first, and then treatment by oxygen was performed continuously. A barrier film was prepared.

Hereinafter, a comparative example of the present invention will be described.
<Comparative Example 1>
A vapor deposition film was prepared in the same manner as in Example 1, except that the pretreatment of the substrate by RIE was not performed.
<Comparative Example 2>
As a processing method, a general in-line plasma processing device (a cooling drum, a processing device on the opposite side of a guide roll is used) is used to perform pre-processing by plasma etching, and an argon gas is used as a processing gas. A vapor-deposited film was prepared in the same manner as in Example 1.
<Comparative Example 3>
As a processing method, a general in-line plasma processing device (a processing device is provided on the opposite side of a cooling drum and a guide roll) is used to perform pre-processing by plasma etching, and an argon / oxygen mixed gas is used as a processing gas. Produced a deposited film in the same manner as in Example 1.

On the vapor deposition barrier films obtained in the above Examples 1 to 4 and the vapor deposition films obtained in Comparative Examples 1 to 3, the following liquid (1) and liquid (2) were mixed at a mixing ratio (wt%) of 6: / 4 to make a mixed solution.
(1) Liquid: 89.6 g of hydrochloric acid (0.1 N) was added to 10.4 g of tetraethoxysilane, and the mixture was stirred for 30 minutes and hydrolyzed to obtain a hydrolyzed solution having a solid content of 3 wt% (in terms of SiO 2).
(2) Liquid: 3 wt% water / isopropyl alcohol solution of polyvinyl alcohol (90:10 by weight of water: isopropyl alcohol)
The solution was applied by a gravure coating method and dried to form a composite coating layer having a thickness of 0.4 μm.

Furthermore, a laminated sample of the above-mentioned vapor-deposited film / unstretched polyethylene (40 μm) was prepared by dry lamination using a two-component curable polyurethane-based adhesive, and oxygen permeability and lamination strength (interface (Cohesion). Table 1 shows the results.
<Evaluation 1>
Oxygen permeability: The film after the vapor deposition process was measured in a 30 ° C.-70% RH atmosphere using Modern Control (MOCON OXTRAN 10 / 50A).
<Evaluation 2>
Laminate strength: The cohesive force between PEN / PET of the laminated sample was measured using a Tensilon universal tester RTC-1250 manufactured by Orientec (JIS Z1707 compliant).

表１より明らかに、実施例１〜４で得られた本発明の高性能バリアフィルムは、比較例１〜３で得られたバリアフィルムに比較して酸素ガスバリア性およびＰＥＮ／ＰＥＴ間のラミネート強度（界面凝集力）に優れている。本発明の高性能バリアフィルムは、ＰＥＮ／ＰＥＴ共押し出しフィルム上に、ＲＩＥによる前処理を行うことで、ＰＥＮ／ＰＥＴの層間凝集力を高め、ＰＥＮ上に金属または無機酸化物蒸着層を設けて、デラミネーションが発生しない高いバリア性能を有する高性能バリアフィルムである。

It is clear from Table 1 that the high performance barrier films of the present invention obtained in Examples 1 to 4 have oxygen gas barrier properties and lamination strength between PEN / PET as compared with the barrier films obtained in Comparative Examples 1 to 3. (Interfacial cohesion). The high-performance barrier film of the present invention is obtained by performing a pretreatment by RIE on a PEN / PET co-extruded film to increase the interlayer cohesion of PEN / PET and providing a metal or inorganic oxide vapor-deposited layer on PEN. And a high-performance barrier film having high barrier performance without delamination.

  The high-performance barrier film of the present invention is used as a gas barrier material used in the field of packaging foods, pharmaceuticals, precision electronic components, and the like.

FIG. 1 is a cross-sectional view illustrating an example of a configuration of a high-performance barrier film of the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 ... Plastic base material 2 ... Inorganic oxide vapor deposition layer 3 ... Composite coating layer 4 ... Pretreatment layer by RIE

Claims (9)

  At least one surface of the polyethylene naphthalate (PEN) / polyethylene terephthalate (PET) co-extruded film is subjected to a pretreatment using plasma in a reactive ion etching (RIE) mode, and a metal having a thickness of 5 to 100 nm is formed thereon. Alternatively, a high-performance barrier film provided with an evaporation layer made of an inorganic compound.   2. The method according to claim 1, wherein the pretreatment using the plasma in the RIE mode is a treatment performed using one kind of gas of argon, nitrogen, oxygen, and hydrogen, or a mixed gas thereof. Performance barrier film. The pretreatment using plasma in the RIE mode has a self-bias value of 200 V or more and 2000 V or less, and an Ed value defined by Ed = plasma density × processing time is 100 V · s · m ⁻² or more and 10000 V · s · m. ^2. The high-performance barrier film according to claim 1, wherein the treatment is performed by low-temperature plasma of ^-2 or less.   The high-performance barrier film according to any one of claims 1 to 3, wherein the metal is aluminum, tin, titanium, or a mixture thereof.   The high-performance barrier film according to any one of claims 1 to 3, wherein the inorganic oxide is aluminum oxide, silicon oxide, or a mixture thereof.   The high-performance barrier film according to any one of claims 1 to 5, wherein the pretreatment and the vapor deposition using the RIE mode plasma are performed in the same film forming machine (in-line film forming machine). .   A composite film having at least one or more of a hydroxyl group-containing polymer compound, a metal alkoxide and / or a hydrolyzate and / or a polymer thereof as a component is provided on the vapor-deposited layer made of the metal or the inorganic compound. The high performance barrier film according to any one of claims 1 to 6.   The high-performance barrier film according to claim 7, wherein the hydroxyl group-containing polymer compound has at least one of polyvinyl alcohol or poly (vinyl alcohol-co-ethylene), cellulose, and starch.   9. The high-performance barrier film according to claim 7, wherein the metal alkoxide is a silane alkoxide or a silane coupling agent.

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