JP2012223992A - Vapor deposition film and packaging material for heat treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vapor deposition film having heat treatment resistance which is resistant to deteriorations in initial gas barrier properties and laminate strength even when subjected to heat treatment by boiling sterilization, retort sterilization, heating cooking, etc., and to breakage by falling and is made to be excellent in sticking properties.SOLUTION: In the vapor deposition film, plasma treatment by a reactive ion etching (RIE) method is applied to one side of a coextrusion stretched film base material made of at least a polyester resin and a polyamide resin, and a vapor deposition film layer of an inorganic compound is formed on the plasma-treated surface.

Description

  The present invention relates to a vapor deposition film for packaging material that is subjected to heat treatment such as boil sterilization, retort sterilization, and cooking.

  In recent years, packaging materials used for packaging foods, non-foods, pharmaceuticals, etc., suppress the alteration of the contents and retain their functions and properties, thereby altering the oxygen, water vapor, or contents that permeate them. It is necessary to have a function of preventing the influence of other gases, and it is required to have a gas barrier property that blocks these gases. Therefore, conventionally, a packaging material using a metal foil such as aluminum, which is less affected by temperature, humidity, etc., as a gas barrier layer has been generally used.

  The packaging material is not easily affected by temperature, humidity, etc., and has a high gas barrier property even after performing heat sterilization treatment such as boil and retort treatment, but on the other hand, because it is a material configuration containing metal foil However, the packaging material is opaque and the contents cannot be confirmed directly, it must be treated as non-combustible after use, and the metal detector cannot be used for inspection.

  As these solutions, for example, a vapor deposition film in which a vapor deposition film of an inorganic oxide such as silicon oxide or aluminum oxide is formed on a polymer film substrate as described in Patent Documents 1 and 2 has been developed. . 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. .

  In addition, in order to improve the adhesion between the polymer film substrate and the deposited film, an easy adhesion layer or an anchor coat layer is provided on the polymer film substrate, or reactive ion etching (RIE) using plasma is performed before in-line. Processing may be performed. In particular, when the heat treatment is performed, the adhesion between the base material and the deposited film tends to be lowered, and delamination may be caused. Therefore, the above method is effective.

  Furthermore, as a method for imparting post-processing suitability to the above-described vapor-deposited film, a water-soluble polymer having a hydroxyl group and one or more kinds of metal alkoxide or metal as a second layer on the inorganic oxide vapor-deposited film A gas barrier film in which a gas barrier film formed by applying a coating agent mainly containing an alkoxide hydrolyzate or an aqueous solution containing at least one of tin chloride or a hydroalcoholic mixed solution and heating and drying is also proposed (patent). Reference 3).

  On the other hand, packaging materials that are heat-treated by boil sterilization, retort sterilization, cooking, etc. are often solid or heavy, so that in addition to gas barrier properties and adhesion, puncture resistance and High demands on film toughness and drop resistance.

  Based on these requirements, a barrier multi-layer stretched film in which a vapor-deposited film layer is provided on at least one side of a biaxial stretch multi-layer film composed of a polyamide resin excellent in puncture resistance and toughness and a polyester resin excellent in dimensional stability and heat resistance. Has been proposed (Patent Document 4).

U.S. Pat. No. 3,442,686 Japanese Patent Publication No.63-28017 Japanese Patent Laid-Open No. 7-164591 JP 2010-131992 A

  The present invention is a heat treatment in which the initial gas barrier property and laminate strength are not easily deteriorated even if heat treatment is performed by boil sterilization, retort sterilization, cooking, etc. It aims at providing the vapor deposition film which has tolerance.

  As a means for solving the above problems, the invention of claim 1 is characterized in that at least one side of a coextruded stretched film base material comprising a polyester resin and a polyamide resin is subjected to a plasma treatment by a reactive ion etching (RIE) method, A vapor-deposited film comprising an inorganic compound vapor-deposited film layer on the plasma-treated surface.

  The invention according to claim 2 is the vapor deposition film according to claim 1, wherein the main component of the vapor deposition film layer of the inorganic compound is aluminum oxide or silicon oxide.

  The invention according to claim 3 is the vapor deposition film according to claim 1 or 2, further comprising an overcoat layer on an upper surface of the vapor deposition film layer.

  The invention according to claim 4 is the vapor-deposited film according to claims 1 to 3, wherein the coextruded stretched film substrate is formed by sequentially laminating a polyester resin, an easily adhesive resin, and a polyamide resin. .

  Moreover, invention of Claim 5 is comprised by the vapor deposition film in any one of Claims 1-4, It is the packaging material for heat processing characterized by the above-mentioned.

  According to the present invention, even when heat treatment such as boil sterilization, retort sterilization, cooking, etc. is performed, the initial gas barrier property and laminate strength are hardly deteriorated, the bag is not easily broken by dropping, and the piercing property is excellent. A vapor deposition film having processing resistance can be provided.

The cross-sectional schematic of an example of the vapor deposition film of this invention. Sectional schematic of another example of the vapor deposition film of this invention.

  Details of the present invention will be described below.

  The vapor-deposited film of the present invention is a coextruded stretched film substrate 1 produced by coextrusion of a polyester resin and a polyamide resin, and has a surface subjected to a plasma treatment layer 2 by (using) a reactive ion etching method on at least one side. And a vapor deposition film layer 3 of an inorganic compound. FIG. 1 is an explanatory view showing a cross-sectional configuration of the vapor deposition film of the present invention.

The polyester resin used in the present invention is composed of a polymer (polyester) having an acid component such as aromatic dicarboxylic acid, alicyclic dicarboxylic acid or aliphatic dicarboxylic acid or a diol component as a structural unit (polymerization unit). It is.

  Examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 6,6 ′-(alkyl). Rangeoxy) di-2-naphthoic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid, and the like. Acid, phthalic acid and 2,6-naphthalenedicarboxylic acid can be used.

  As the alicyclic dicarboxylic acid component, for example, cyclohexane dicarboxylic acid or the like can be used. As the aliphatic dicarboxylic acid component, for example, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like can be used. These acid components may be used alone or in combination of two or more.

  Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol. 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol and 2,2′-bis (4 '-Β-hydroxyethoxyphenyl) propane and the like can be used, and among them, ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, diethylene glycol and the like can be preferably used, and particularly preferably Echile It can be used glycol. These diol components may be used alone or in combination of two or more.

  Polyamide resin is, for example, crystalline polyamide, poly ε-capramide (nylon 6), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebamide (nylon 610) , Polyhexamethylene dodecamide (nylon 612), polyundecamethylene adipamide (nylon 116), polyundecanamide (nylon 11), polydodecanamide (nylon 12), polyhexamethylene isophthalamide (nylon 6I), polyhexa Examples include methylene terephthalamide (nylon 6T), polynonamethylene terephthalamide (nylon 9T), polymetaxylylene adipamide (nylon MXD6), and the like. These may be used alone, or may be a polyamide copolymer containing two or more different crystalline polyamide components, or a mixture thereof.

  Examples of amorphous polyamides include polycondensates of isophthalic acid / terephthalic acid / hexamethylenediamine / bis (3-methyl-4-aminocyclohexyl) methane, terephthalic acid / 2,2,4-trimethylhexamethylenediamine / 2. , 4,4-trimethylhexamethylenediamine polycondensate, isophthalic acid / bis (3-methyl-4-aminocyclohexyl) methane / ω-laurolactam polycondensate, isophthalic acid / terephthalic acid / hexamethylenediamine polycondensate Condensate, isophthalic acid / 2,2,4-trimethylhexamethylenediamine / 2,4,4-trimethylhexamethylenediamine polycondensate, isophthalic acid / terephthalic acid / 2,2,4-trimethylhexamethylenediamine / 2 , 4,4-trimethylhexamethylenediamine polycondensate, Sofutaru acid / bis polycondensate of (3-methyl-4-aminocyclohexyl) methane / .omega.-laurolactam can be cited.

  An antistatic agent, an ultraviolet ray inhibitor, a plasticizer, a lubricant, or the like may be used on the surface of the coextruded stretched film substrate 1.

  The thickness of the coextruded stretched film substrate 1 is not particularly limited, but considering the suitability as a packaging material and the possibility of laminating other layers, the polyester resin layer and the polyami resin layer A total thickness of 6 to 30 μm is preferable.

  The deposited film shown in FIG. 1 is pretreated by reactive ion etching using plasma on the surface of the substrate in order to strengthen the adhesion between the coextruded stretched film substrate 1 and the deposited film layer 3. A plasma treatment layer 2 is formed. By performing the treatment by RIE, the surface of the coextruded stretched film substrate 1 made of plastic is made to have a functional group by utilizing the generated radicals and ions, and the surface is ion-etched. It is possible to simultaneously obtain two physical effects such as smoothing by removing impurities and the like. By forming such a plasma processing layer 2, it becomes possible to form the vapor deposition film layer 3 densely on it.

  As a result, the adhesion between the co-extruded stretched film substrate 1 and the vapor deposition film layer 3 can be strengthened, the gas barrier property is improved, the generation of cracks can be prevented, and heat sterilization treatment such as retort sterilization is performed. In such a case, delamination does not occur between them.

  In general, the thickness of the deposited film layer 3 made of an inorganic compound mainly composed of aluminum oxide or silicon oxide is preferably within a range of 5 to 300 nm, and the value is appropriately selected depending on the required function. 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. In addition, when the film thickness exceeds 300 nm, the thin film cannot maintain flexibility, and there is a problem because the thin film may be bent or pulled to cause cracks in the thin film. More preferably, it exists in the range of 10-150 nm.

  There are various methods for forming the deposited film layer 3 on the stretched film substrate 1 by coextrusion, but thin film forming means such as a vacuum deposition method, a sputtering method, and an ion plating method can be used. However, considering productivity, the vacuum deposition method is the best at present. As a heating means of the vacuum evaporation method, it is preferable to use any one of an electron beam heating method, a resistance heating method, and an induction heating method, but the electron beam heating method should be used in consideration of the wide selection of evaporation materials. Is more preferable. In order to improve the adhesion between the vapor-deposited film layer and the coextruded stretched film substrate and the denseness of the vapor-deposited film layer, it is also possible to perform vapor deposition using a plasma assist method or an ion beam assist method.

  Further, an easily adhesive resin layer may be provided between the polyester resin layer and the polyamide resin layer of the coextruded stretched film substrate 1. By providing an easy-adhesive resin layer, it is possible to increase the adhesion between different resins. Examples of the adhesive resin used in the method of the present invention include known general adhesive resins. Specifically, acrylic ester resin, polyester resin, polyurethane resin, carboxylic acid-modified hydrogenated styrene-ethylene-butylene-styrene block copolymer resin, carboxylic acid-modified ethylene vinyl acetate copolymer resin, carboxylic acid-modified Examples include polyester-based thermoplastic elastomers. When applied to amorphous polyester resin (B) and EVOH-based resin, carboxylic acid-modified hydrogenated styrene-ethylene-butylene-styrene block copolymer resin or carboxylic acid-modified Ethylene vinyl acetate copolymer resins and carboxylic acid-modified polyester thermoplastic elastomers are preferably used.

The carboxylic acid-modified resin is a resin obtained by chemically bonding an unsaturated carboxylic acid or an anhydride thereof to each resin by an addition reaction or a graft reaction. The unsaturated carboxylic acid or anhydride thereof used for modification is not particularly limited. For example, monounsaturated carboxylic acids such as acrylic acid and methacrylic acid and anhydrides thereof, or dicarboxylic acids such as fumaric acid and maleic acid and anhydrides thereof. Things.

  The amount of the unsaturated carboxylic acid or anhydride thereof contained in the carboxylic acid-modified resin is usually 0.001 to 3% by weight, preferably 0.01 to 1% by weight, particularly preferably 0.03 to 0.3%. 5% by weight. When the amount of modification in the modified product is small, the adhesiveness may be insufficient. On the other hand, when the amount is large, a crosslinking reaction occurs and the moldability tends to deteriorate. In addition, as an easily adhesive resin layer, you may comprise only 1 type of resin which satisfies the said requirements, and may mix 2 or more types of resin. Furthermore, rubber / elastomer components such as EVOH resin, polyisobutylene, α-olefin-propylene rubber, and other thermoplastic resins can be blended.

  As mentioned above, although the vapor deposition film of this invention was demonstrated, this invention is not limited to the thing of such a structure, As shown in FIG. 2, the overcoat layer 4 is further provided on the vapor deposition film layer 3. As shown in FIG. It may be done.

  Next, the overcoat layer 4 will be described in detail. The overcoat layer 4 is a coating layer having a gas barrier property, for example, using a coating agent mainly composed of an aqueous solution or water / alcohol mixed solution containing a water-soluble polymer and one or more metal alkoxides or hydrolysates thereof. It is a layer formed. As a coating agent, for example, a solution obtained by mixing a water-soluble polymer dissolved in an aqueous (water or water / alcohol mixed) solvent with a metal alkoxide directly or hydrolyzed beforehand is used. . The overcoat layer 4 is formed by coating such a solution on the deposited film layer 3 and then drying by heating. Each component contained in the coating agent will be described in more detail.

  Examples of the water-soluble polymer used in the coating agent include polyvinyl alcohol, polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate and the like. In particular, when polyvinyl alcohol (hereinafter abbreviated as PVA) is used as the water-soluble polymer of the coating agent, it is preferable because gas barrier properties are most excellent. PVA here is generally obtained by saponifying polyvinyl acetate. As PVA, for example, complete PVA in which only several percent of acetic acid groups remain can be used from so-called partially saponified PVA in which several tens percent of acetic acid groups remain. I do not care.

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

  A known additive such as an isocyanate compound, a silane coupling agent, a dispersant, a stabilizer, a viscosity modifier, a colorant, or the like is added to the solution as necessary to the extent that gas barrier properties are not impaired. . As a method for applying the coating agent, conventionally known methods such as a dipping method, a roll coating method, a screen printing method, a spray method, and a gravure printing method that are usually used can be used.

The thickness of the overcoat layer 4 is not particularly limited because the optimum condition varies depending on the type of coating agent, the processing machine, and the processing conditions. However, when the thickness after drying is 0.01 μm or less, a uniform coating film cannot be obtained and sufficient gas barrier properties may not be obtained. On the other hand, if the thickness exceeds 50 μm, cracks are likely to occur in the film, which may be a problem. It is preferably in the range of 0.01 to 50 μm, more preferably in the range of 0.1 to 10 μm.

  Moreover, a printing layer, an intervening film, a sealant layer, and the like can be laminated on the overcoat layer 4 to form a packaging material. The intervening film is used, for example, when the packaging material for heat treatment is produced using the vapor deposition film according to the present invention, in order to further increase the bag breaking strength and piercing strength, or to form a printing substrate. Generally, a film selected from a biaxially stretched nylon film, a biaxially stretched polyethylene terephthalate film, and a biaxially stretched polypropylene film is employed in terms of mechanical strength and heat stability. The thickness is determined according to the material and required quality, but is generally in the range of 10 to 30 μm.

  Furthermore, a sealant layer is provided so that it may become an adhesive layer at the time of producing the packaging material for heat processing, for example using the vapor deposition film which concerns on this invention. 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 It is formed of a resin such as a metal cross-linked product. The thickness is determined according to the purpose, but is generally in the range of 15 to 200 μm. Moreover, it is also possible to laminate | stack these printing layers, an intermediate | middle film, a sealant layer, etc. as needed also to the surface in which the vapor deposition film layer of a base material is not provided.

  Examples of the vapor deposition film of the present invention and the packaging material for heat treatment using the same will be specifically described below. The present invention is not limited to these examples.

<Example 1>
The polyamide resin surface of a co-extruded biaxially stretched film of a polyester resin and a polyamide resin (trade name “Heptax” manufactured by Gunze Co., Ltd.) was subjected to plasma treatment by a reactive ion etching method under the following conditions.
[Plasma treatment conditions]
・ Applied power: 120W
・ Processing time: 0.1 sec
・ Processing gas: Argon gas ・ Processing unit pressure: 2.0Pa
・ High frequency power supply: 13.56 MHz

Next, aluminum oxide is evaporated to a thickness of 15 nm on the plasma-treated surface by reactive vapor deposition using an electron beam heating method with aluminum as a vapor deposition source, a reaction gas as oxygen, and a pressure set to 2 × 10 ⁻¹ Pa. A vapor-deposited film having a film layer was produced.

<Example 2>
Plasma treatment was performed by the reactive ion etching method in the same manner as in Example 1 except that the applied power was 250 W.

Next, aluminum oxide is evaporated to a thickness of 12 nm on the plasma treated surface by reactive vapor deposition using an electron beam heating method with aluminum as a vapor deposition source, a reaction gas as oxygen, and a pressure set to 2 × 10 ⁻¹ Pa. A vapor-deposited film having a film layer was produced.

<Example 3>
Plasma treatment was performed by the reactive ion etching method in the same manner as in Example 1 except that the applied power was 250 W.

  Next, the vapor deposition film which has a 23-nm-thick silicon oxide vapor deposition film layer on the said plasma processing surface was produced using the electron beam heating system.

<Comparative Example 1>
Electron beam heating on a polyamide resin surface of a polyester resin and polyamide resin co-extruded biaxially stretched film (trade name “Heptax” manufactured by Gunze Co., Ltd.) with oxygen as the reaction gas and a pressure of 2 × 10 ⁻¹ Pa. A vapor deposition film having an aluminum oxide vapor deposition film layer having a thickness of 17 nm was produced by reactive vapor deposition using the method.

<Comparative example 2>
A 23 nm thick silicon oxide vapor deposition film layer is formed on the polyamide resin surface of a co-extruded biaxially stretched film of a polyester resin and a polyamide resin (trade name “Heptax” manufactured by Gunze Co., Ltd.) by vapor deposition using an electron beam heating method. A vapor deposition film was produced.

<Comparative Example 3>
An untreated surface of a polyethylene terephthalate (PET) film having a thickness of 12 μm was subjected to plasma treatment by a reactive ion etching method under the following conditions.
[Plasma treatment conditions]
・ Applied power: 120W
・ Processing time: 0.1 sec
・ Processing gas: Argon gas ・ Processing unit pressure: 2.0Pa
・ High frequency power supply: 13.56 MHz

Next, vapor deposition having an aluminum oxide vapor deposition film layer having a thickness of 15 nm is formed on the plasma processing surface by reactive vapor deposition using an electron beam heating method with oxygen as a reaction gas and a pressure of 2 × 10 ⁻¹ Pa. A film was prepared.

On the vapor deposition film layer of the vapor deposition film obtained in Examples 1-3 and Comparative Examples 1-3, the solution which mixed A liquid and B liquid shown below by the ratio of 6/4 with a compounding ratio (wt%) is prepared. It was applied and dried by a gravure coating method to form an overcoat layer having a thickness of 0.4 μm.
[Composition of Liquid A and Liquid B]
Liquid A: A hydrolyzed solution having a solid content of 3 wt% (in terms of SiO ₂ ) obtained by adding 89.6 g of hydrochloric acid (0.1N) to 10.4 g of tetraethoxysilane and stirring for 30 minutes for hydrolysis.
Liquid B: 3 wt% water / isopropyl alcohol solution of polyvinyl alcohol (90:10 by weight ratio of water: isopropyl alcohol).

  Further, a stretched nylon film having a thickness of 15 μm and an unstretched polypropylene film having a thickness of 70 μm are sequentially laminated on each of the overcoat layers by dry lamination using a two-component curable polyurethane adhesive. A retort packaging material, which is an example of a heat treatment packaging material, was produced.

<Evaluation items and evaluation methods>
Using the packaging material for retort, making a pouch with 4 sides as a seal part, filling with water as the contents, then performing retort sterilization at 121 ° C for 30 minutes, oxygen permeability after retort sterilization, laminating The strength, drop test, and puncture strength were evaluated by the following methods. The results are shown in Table 1.

-Oxygen permeability (unit: cc / m ² / day) Measured with an oxygen permeability measuring device (manufactured by Mocon, PERMATRAN 3/30) under a condition of 30 ° C. to 70% RH.
・ Measure the adhesive strength between laminate strength (unit: N / 15 mm) to vapor-deposited film / polypropylene film.
・ Drop test-Drop the pouch 50 times in the vertical direction so that the seal hits the concrete floor from a height of 1 m, and check for bag breakage.
・ Puncture strength ~ From the outer surface of the packaging material, a needle with a diameter of 1 mmφ is pierced at a speed of 50 mm / min, and the puncture strength (unit: N) required for the needle to penetrate the packaging material is measured.

DESCRIPTION OF SYMBOLS 1 ... Co-extrusion stretched film base material 2 ... Plasma processing layer 3 ... Deposition film layer 4 ... Overcoat layer

Claims (5)

  At least one surface of a coextruded stretched film base material composed of a polyester resin and a polyamide resin is subjected to a plasma treatment by a reactive ion etching (RIE) method, and a vapor deposition film layer of an inorganic compound is provided on the plasma treatment surface. Vapor deposited film.   The vapor-deposited film according to claim 1, wherein a main component of the vapor-deposited film layer of the inorganic compound is aluminum oxide or silicon oxide.   The deposited film according to claim 1, further comprising an overcoat layer on an upper surface of the deposited film layer.   The vapor-deposited film according to claim 1, wherein the co-extrusion stretched film substrate is formed by sequentially laminating a polyester resin, an easily adhesive resin, and a polyamide resin.   It is comprised with the vapor deposition film in any one of Claims 1-4, The packaging material for heat processing characterized by the above-mentioned.

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