JP4924806B2 - Gas barrier laminate - Google Patents

Description

  The present invention relates to a laminated body for packaging used in the packaging field of foods, daily necessities, pharmaceuticals, etc., or a laminated body used for electronic equipment-related members, etc., and packaging that requires particularly high gas barrier properties. The present invention relates to a transparent laminate having high gas barrier properties, which is preferably used for packaging in the field, electronic device-related members, and the like.

  Packaging materials used for packaging food, daily necessities, pharmaceuticals, etc. are made of oxygen, water vapor, or other gas that alters the contents to penetrate 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, and it is required to have a gas barrier property or the like for blocking these. In general packaging materials that require gas barrier properties, among polymers, vinylidene chloride resin films that are relatively excellent in gas barrier properties or films coated with them have been often used. However, these films cannot be used as packaging materials that require high gas barrier properties. Therefore, for those having the above requirements, a packaging material using a metal foil made of a metal such as aluminum as a gas barrier layer has to be used.

  However, packaging materials using metal foils made of metal such as aluminum have high gas barrier properties without the influence of temperature and humidity, but the contents cannot be confirmed through the packaging materials. However, there are a number of drawbacks, such as the fact that the metal detector must be treated as an incombustible material and the metal detector cannot be used for the inspection.

Therefore, as a packaging material that overcomes these drawbacks, for example, a vapor-deposited thin film made of an inorganic compound such as silicon oxide, aluminum oxide, and magnesium oxide as described in Patent Documents 1 and 2, etc., is formed by vacuum evaporation or sputtering. A film formed on a plastic film by a thin film forming means such as a method is put on the market. These vapor-deposited films are known to have transparency and gas barrier properties such as oxygen and water vapor, and are suitable as packaging materials having transparency and gas barrier properties that cannot be obtained with metal foil or the like.
U.S. Pat. No. 3,442,686 Japanese Patent Publication No.63-28017

In a transparent vapor deposition film, when the film thickness of an inorganic compound is thin, protrusions such as a lubricant on the substrate cannot be covered, and sufficient barrier properties cannot be obtained. In addition, a high barrier property is expected by increasing the film thickness of the inorganic compound. However, even if the film thickness is actually increased, cracks are generated by the internal stress of the film, and the barrier property is saturated. The phenomenon that it falls or conversely occurs. Therefore, obtaining a high barrier property in the film thickness of the inorganic compound in consideration of productivity is a big problem.
Further, in order to continuously process vapor deposition, printing, and the like on a long plastic film, the film is unwound from the wound state and processed. At this time, if the film does not have a certain slip property, the film cannot be unwound and the processing suitability is lowered. For this reason, the film is filled with a lubricant having a certain particle diameter as described above, and the lubricant forms protrusions. If such a film is provided with a vapor deposition layer as it is by vacuum vapor deposition or the like, there is a risk that problems such as pinholes may occur.

  Therefore, the object of the present invention is that even if protrusions such as a lubricant are formed on a base material such as a transparent plastic film, defects such as pinholes occur due to the film thickness of the inorganic compound layer suitable for production. Therefore, an object of the present invention is to provide a cas barrier laminate capable of obtaining a high barrier property.

  In the present invention, even if a lubricant projection is formed on the plastic film, the above-mentioned problems can be solved by providing a specific resin layer on the surface of the film and specifying the surface state. It was.

The invention according to claim 1 is a gas barrier laminate in which a resin layer and an inorganic compound layer are laminated in this order on at least one surface of polyethylene terephthalate as a transparent plastic substrate,
The resin layer is formed by applying and drying a solution obtained by mixing a hydrolyzate of tetraethoxysilane , polyvinyl alcohol, and a silane coupling agent containing an epoxy group as an organic functional group ,
The center line average surface roughness of the formed resin layer is 20 nm or less, and the maximum height is 100 nm or less,
The gas barrier laminate, wherein the inorganic compound layer is a silicon oxide film and is laminated after the surface of the resin layer is surface-treated with plasma.

The invention according to claim 2 is a gas barrier laminate in which a resin layer and an inorganic compound layer are laminated in this order on at least one surface of polyethylene terephthalate as a transparent plastic substrate,
The resin layer is formed by applying and drying a solution obtained by mixing a hydrolyzate of tetraethoxysilane , polyvinyl alcohol, and a silane coupling agent containing an epoxy group as an organic functional group ,
The center line average surface roughness of the formed resin layer is 20 nm or less, and the maximum height is 100 nm or less,
The gas barrier laminate, wherein the inorganic compound layer is a silicon oxide film and is laminated on the resin layer by a plasma CVD method.

  According to the gas barrier laminate of the present invention, the resin layer is formed on at least one surface of the transparent plastic substrate so that the center line average surface roughness is 20 nm or less and the maximum height is 100 nm or less. The presence of this resin layer suppresses the influence of protrusions such as a lubricant on the base material. Further, an inorganic compound layer is laminated on the resin layer after the plasma treatment or by the plasma CVD method. Thereby, the silicon compound or its hydrolyzate existing on the surface of the resin layer is activated, an interaction between the inorganic compound in the inorganic compound layer and the compound occurs, and a high barrier property is expressed.

  According to the present invention, even if protrusions such as a lubricant are formed on a substrate such as a transparent plastic film, the film thickness of the inorganic compound layer suitable for production does not cause problems such as pinholes. Thus, it is possible to provide a residue barrier laminate that can obtain high barrier properties.

  The gas barrier laminate of the present invention will be described in detail along the embodiments. FIG. 1 is a side sectional view showing an embodiment of the gas barrier laminate of the present invention, in which a transparent plastic substrate 1, a resin layer 2, and an inorganic compound layer 3 are sequentially laminated in the thickness direction.

  The transparent plastic substrate used in the present invention is preferably a transparent film in order to make use of the transparency of the barrier layer. For example, polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polycarbonate films (PC), polyether sulfone (PES), polycarbonate films, polyarylate films, polyolefin films such as polyethylene and polypropylene, cyclic cyclo A cycloolefin film containing olefin, a polystyrene film, a polyamide film, a polyvinyl chloride film, a polyacrylonitrile film, a polyimide film, or the like is used.

  The transparent plastic substrate may be either stretched or unstretched, and preferably has mechanical strength and dimensional stability. These are processed into a film and used. There is no problem even if the film is arbitrarily stretched in the biaxial direction. In addition, various known additives and stabilizers such as antistatic agents, ultraviolet inhibitors, plasticizers, lubricants, and the like may be used on the surface of the base material to improve adhesion to the thin film. Therefore, corona treatment, low temperature plasma treatment, ion bombardment treatment may be performed as pretreatment, and chemical treatment, solvent treatment, etc. may be performed. As described above, in the present invention, even if a lubricant is blended in the transparent plastic base material and the protrusions are formed, the influence is reduced by the presence of the resin layer, and excellent barrier properties can be provided. .

The resin layer 2 formed on the transparent plastic substrate 1 of the present invention is Si (OR ¹ ) ₄ (R ¹ is a hydrolyzable group such as CH ₃ , C ₂ H ₅ , C ₂ H ₄ OCH ₃ ). It is a film formed by applying a solution (coating agent) in which a silicon compound or a hydrolyzate thereof and a water-soluble polymer having a hydroxyl group are mixed and drying by heating, and exhibits a smooth surface of the resin layer The centerline average surface roughness should be 20 nm or less and the maximum height should be 100 nm or less. More preferably, the center line average surface roughness is 10 nm or less and the maximum height is 50 nm or less. In addition, the centerline average surface roughness and the maximum height here mean Ra and Rmax shown in JIS B0601.
Each component contained in the coating agent will be described in detail below.

  Examples of the water-soluble polymer used in the coating agent in the present invention include polyvinyl alcohol, poly (vinyl alcohol-co-ethylene), polyvinyl pyrrolidone, starch, cellulose, methyl cellulose, carboxymethyl cellulose, and sodium alginate. Among these, it is preferable to have at least one selected from the group consisting of polyvinyl alcohol, poly (vinyl alcohol-co-ethylene), cellulose, and starch as a component. In particular, when polyvinyl alcohol (hereinafter referred to as PVA) is used for the coating agent of the gas barrier laminate of the present invention, the gas barrier property is most excellent. The PVA here is generally obtained by saponifying polyvinyl acetate, from a so-called partially saponified PVA in which several tens percent of acetic acid groups remain to completely saponified PVA in which only several percent of acetic acid groups remain. Including, but not limited to.

  It is a well-known fact that metal alkoxides condense after hydrolysis to form a ceramic film such as glass. However, since metal oxides are hard and cracks easily occur due to distortion due to volume reduction during condensation, it is very difficult to form a thin, transparent and uniform condensate film on the film. Therefore, it is possible to form a film by adding flexibility to the structure and preventing cracks by adding a polymer. However, a resin layer made of a mixture of a metal alkoxide or a hydrolyzate thereof and a water-soluble polymer having a hydroxyl group swells and dissolves in water because it consists of hydrogen bonds. Even if there is a synergistic effect due to the laminated structure with the vapor deposition layer, deterioration is unavoidable in processing under severe conditions.

Therefore, R ² Si (OR ³ ) ₃ (R ³ is a hydrolyzable group such as CH ₃ , C ₂ H ₅ , C ₂ H ₄ OCH ₃ , R ² is an organic functional group), a so-called silane cup. This swelling can be prevented by adding a ring agent. R ² Si (OR ³ ) ₃ forms a hydrogen bond with Si (OR ¹ ) ₄ , a water-soluble polymer, due to a hydrolyzable group, so that it does not easily become a barrier hole, while an organic functional group forms a network. Prevents hydrogen bond swelling. Among them, those having a vinyl group, an epoxy group, a methacryloxy group, a ureido group, and an isocyanate group are further improved in water resistance because the functional group is hydrophobic. The addition amount of the silane coupling agent can be added at an arbitrary ratio with respect to the mass of the resin layer after drying, but it can be preferably added at a ratio of 1 to 20%.

When tetraethoxysilane is used for Si (OR ¹ ) ₄ and PVA is used for the water-soluble polymer, the metal alkoxide or the hydrolyzate of the metal alkoxide is converted into a metal oxide (for example, SiO ₂ ) and the water content. As for the weight ratio with the functional polymer, SiO ₂ / PVA is more preferably 100/10 to 100/100. When the PVA is less than 100/10, the inorganic compound layer 3 is hard, the flexibility is low, and cracks and the like are likely to deteriorate. Moreover, if PVA is 100/100 or more, it will become a cause of water resistance inhibition.

  The coating solution for forming the resin layer 2 is stabilized by clay minerals such as isocyanate compounds, colloidal silica and smectite, in consideration of adhesion with ink and adhesive, wettability, and prevention of cracking due to shrinkage. Known additives such as a colorant, a colorant, and a viscosity modifier can be added within a range that does not impair gas barrier properties and water resistance.

  The thickness of the resin layer 2 after drying is not particularly limited, but if it is less than 0.1 μm, it is difficult to smooth the unevenness of the substrate, and if the thickness exceeds 50 μm, cracks may easily occur. 0.1 to 50 μm is desirable.

  As a method for forming the resin layer 2, a normal coating method can be used. For example, dipping method, roll coating, gravure coating, reverse coating, air knife coating, comma coating, die coating, screen printing method, spray coating, gravure offset method and the like can be used. It apply | coats on a base material using these coating systems.

  The resin layer 2 can be dried by hot air drying, hot roll drying, high-frequency irradiation, infrared irradiation, UV irradiation, etc., as long as it heats the resin layer 2 and blows off water molecules. Two or more may be combined.

  Subsequently, the inorganic compound layer 3 made of an inorganic compound is formed on the resin layer 2 by a vacuum vapor deposition method, but it is necessary to form the inorganic compound layer 3 made of an inorganic compound after treating the resin layer 2 with plasma. is there. By depositing an inorganic compound after the plasma treatment, the silicon compound or its hydrolyzate existing on the surface of the resin layer 2 is activated to form an inorganic compound. Interaction occurs, and high barrier properties are expressed. For this reason, the plasma treatment and the formation of the inorganic compound layer 3 made of an inorganic compound are preferably performed in the same vacuum apparatus.

  The inorganic compound layer 3 made of an inorganic compound is made of oxides such as silicon, aluminum, titanium, zirconium, tin, magnesium, nitrogen, fluoride units, or a composite thereof, and has transparency and oxygen, water vapor, etc. Any gas barrier property may be used. Among these, aluminum oxide, silicon oxide, silicon nitride, and silicon oxynitride are particularly preferable. Optimally, silicon oxide, silicon nitride, and silicon oxynitride are used.

  A method of forming the inorganic compound layer 3 made of an inorganic compound on the resin layer 2 after the plasma treatment can be formed by a normal vacuum deposition method. For example, reactive vapor deposition, sputtering, ion plating, plasma vapor deposition (PECVD), or the like can be used. If the inorganic compound layer 3 is formed by the plasma CVD method, the film formation is performed in the plasma, so that the activation and film formation of the resin layer 2 are possible at the same time, which is considered particularly suitable.

  The optimum condition of the thickness of the inorganic compound layer 3 made of an inorganic compound varies depending on the type and configuration of the inorganic compound used, but is generally within the range of 5 to 1000 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, when the film thickness exceeds 1000 nm, it is difficult to maintain flexibility in the thin film, and productivity is lowered.

  The gas barrier laminate of the present invention will be further described with reference to specific examples.

[Example 1]
Using a polyethylene terephthalate (hereinafter referred to as PET) having a thickness of 100 μm as a base material, the following composition is combined on one side, and a coating agent formed by mixing at a predetermined ratio is applied by a bar coater and dried at 120 ° C. for 1 minute by a dryer. A resin layer having a thickness of about 0.5 μm was formed. The obtained resin layer had a centerline average surface roughness of 12 nm and a maximum height of 43 nm. Further, after the plasma treatment was performed on the surface of the resin layer, an inorganic compound layer having a thickness of 40 nm was formed by a vacuum vapor deposition method using an electron beam heating method using SiO (silicon oxide) as a vapor deposition source to obtain a gas barrier laminate.

[Example 2]
A coating agent formed by using PET having a thickness of 100 μm as a base material, combining the following composition on one side and mixing at a predetermined ratio is applied by a bar coater and dried at 120 ° C. for 1 minute in a drier. A 5 μm resin layer was formed. The obtained resin layer had a centerline average surface roughness of 12 nm and a maximum height of 43 nm. Further, using a source gas mixed with hexamethyldisiloxane (HMDSO): oxygen = 10: 100, a silicon oxide film was formed to a thickness of 30 nm by a plasma CVD method to obtain a gas barrier laminate.

[Example 3]
A coating agent formed by using PET having a thickness of 100 μm as a base material, combining the following composition on one side and mixing at a predetermined ratio is applied by a bar coater and dried at 120 ° C. for 1 minute in a drier. A 5 μm resin layer was formed. The center line average surface roughness of the obtained resin layer was 15 nm, and the maximum height was 39 nm. Further, using a source gas mixed with hexamethyldisiloxane (HMDSO): oxygen = 10: 100, a silicon oxide film was formed to a thickness of 30 nm by a plasma CVD method to obtain a gas barrier laminate.

[Comparative Example 1]
A silicon oxide film having a thickness of 30 nm was formed by plasma CVD using a raw material gas mixed with hexamethyldisiloxane (HMDSO): oxygen = 10: 100 on one side of PET having a thickness of 100 μm as a base material. The center line average surface roughness of the PET substrate was 32 nm, and the maximum height was 152 nm.

[Comparative Example 2]
A silicon oxide film having a thickness of 30 nm is formed by a plasma CVD method using a raw material gas mixed with hexamethyldisiloxane (HMDSO): oxygen = 10: 100 on one side of polyethylene naphthalate (hereinafter PEN) having a thickness of 100 μm. did. The center line average roughness of the PEN substrate was 10 nm, and the maximum height was 80 nm.

[Comparative Example 3]
A coating agent formed by using PET having a thickness of 100 μm as a base material, combining the following composition on one side and mixing at a predetermined ratio is applied by a bar coater and dried at 120 ° C. for 1 minute in a drier. A 5 μm resin layer was formed. The obtained resin layer had a centerline average surface roughness of 12 nm and a maximum height of 43 nm. A plasma deposition was not performed on this resin layer, and a vapor deposition layer having a film thickness of 40 nm was formed by a vacuum vapor deposition method using an electron beam heating method using SiO (silicon oxide) as a vapor deposition source.

[Comparative Example 4]
A PEN having a thickness of 100 μm was used as a base material, and a source gas mixed with HMDSO: oxygen = 10: 100 was used on one surface thereof, and a 30 nm silicon oxide film was formed by plasma CVD. Furthermore, the following compositions were combined and a coating agent formed by mixing at a predetermined ratio was applied by a bar coater and dried at 120 ° C. for 1 minute by a dryer to form a resin layer having a film thickness of about 0.5 μm.

(Adjustment of gas barrier coating agent)
(A): 17.9 g of tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ , hereinafter referred to as TEOS) and 72.1 g of hydrochloric acid (0.1N) are added to 10 g of methanol, and the mixture is stirred for 30 minutes for hydrolysis. A hydrolyzed solution having a solid content of 5% (weight ratio in terms of SiO ₂ ).
(B): 5% (weight ratio) of polyvinyl alcohol: water / methanol alcohol = 95: 5 (weight ratio) aqueous solution.
(C): Hydrochloric acid (1N) was gradually added to β- (3,4-epoxycyclohexyl) trimethoxysilane and isopropyl alcohol (IPA solution), stirred for 30 minutes, hydrolyzed, and then water / IPA = 1. / 1 Hydrolysis solution adjusted to a solid content of 5% (weight ratio R ₂ Si (OH) ₃ conversion) by hydrolysis with the solution.
(D): Standard particles of silica having a particle size of 0.5 μm.

(Composition ratio of gas barrier film coating agent)
A: Solid SiO ₂ content of TEOS (converted value)
B: PVA solid content C: R ₂ Si (OH) ₃ solid content (converted value) of β- (3,4-epoxycyclohexyl) trimethoxysilane
All compounding ratios are solid weight ratios.
Example 1 ... A / B / C = 70/20/10
Example 2 ... A / B / C = 70/20/10
Example 3 ... A / B / D = 70/20/10
Comparative Example 1 ... Uncoated Comparative Example 2 ... Uncoated Comparative Example 3 ... ... A / B / C = 70/20/10
Comparative Example 4 ... A / B / C = 70/20/10

In the examples and comparative examples, the bath barrier property was measured using a water vapor transmission rate measuring device (PERMATRAN-W 3/33 manufactured by MOCON) under the conditions of 40 ° C. and relative humidity of 90%. The results are shown in the table below. The barrier property of the PET film used for the substrate is 5.0 g / m ² / day, and the barrier property of the PEN film is 2.0 g / m ² / day.

  As shown in Comparative Examples 1 and 2 according to Table 1, a PET film having a low surface smoothness or a PEN film having a high surface smoothness but no resin layer does not have a barrier property. Further, Comparative Example 3 in which the plasma treatment was not performed despite the formation of the resin layer is also inferior in barrier properties. Although the comparative example 4 has a configuration opposite to that of the present invention in which a film layer is formed on the film of the comparative example 2, the barrier property is hardly improved as compared with the comparative example 2. On the other hand, it turns out that the laminated body of Examples 1-3 produced by this invention has shown favorable barrier property.

  Even if a protrusion such as a lubricant is formed on a base material such as a transparent plastic film, the cas barrier laminate of the present invention has problems such as pinholes due to the film thickness of an inorganic compound layer suitable for production. High barrier properties can be obtained without the need for a laminate for packaging used in the packaging field of foods, daily necessities, pharmaceuticals, etc., or a laminate used for electronic equipment-related materials, especially high gas barrier properties. It is preferably used for packaging in the packaging field and electronic equipment related members.

It is a schematic sectional drawing explaining the structure of the gas barrier laminated body of this invention.

Explanation of symbols

1 ... Transparent plastic substrate, 2 ... Resin layer, 3 ... Inorganic compound layer.

Claims (2)

A gas barrier laminate in which a resin layer and an inorganic compound layer are laminated in this order on at least one surface of polyethylene terephthalate as a transparent plastic substrate,
The resin layer is formed by applying and drying a solution obtained by mixing a hydrolyzate of tetraethoxysilane , polyvinyl alcohol, and a silane coupling agent containing an epoxy group as an organic functional group ,
The center line average surface roughness of the formed resin layer is 20 nm or less, and the maximum height is 100 nm or less,
The gas barrier laminate, wherein the inorganic compound layer is a silicon oxide film and is laminated after the surface of the resin layer is surface-treated with plasma. A gas barrier laminate in which a resin layer and an inorganic compound layer are laminated in this order on at least one surface of polyethylene terephthalate as a transparent plastic substrate,
The resin layer is formed by applying and drying a solution obtained by mixing a hydrolyzate of tetraethoxysilane , polyvinyl alcohol, and a silane coupling agent containing an epoxy group as an organic functional group ,
The center line average surface roughness of the formed resin layer is 20 nm or less, and the maximum height is 100 nm or less,
The gas barrier laminate, wherein the inorganic compound layer is a silicon oxide film and is laminated on the resin layer by a plasma CVD method.

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