JP2005096353A - Gas-barrier film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas-barrier film laminate which makes the contents be seen through owing to its excellent transparency and a metal detector usable, does not use a substance causing environmental pollution, has high gas-barrier properties under high temperature and high humidity, and is suitable for a packaging material keeping the gas-barrier properties even after boiling and retort sterilization. <P>SOLUTION: In the gas-barrier film laminate, on at least one side of a substrate of a plastic material, the first layer of a vapor deposition layer of an oxidized inorganic compound and the second layer of a gas-barrier coat layer obtained by applying a solution prepared by mixing silicon dioxide having micro secondary particles of lamination structure in which extremely thin piece primary particles having a nano scale size thickness are laminated in parallel and a water soluble polymer having hydroxyl groups and heating/drying the solution are laminated in turn. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a laminate for packaging used in the field of packaging foods, beverages, non-foods such as pharmaceuticals and electronic components, and the contents of oxygen and water vapor in the atmosphere by maintaining particularly high gas barrier properties. It is related with the gas barrier film laminated body which interrupts | blocks and suppresses deterioration and a quality change.

  In recent years, packaging materials used for packaging foods, beverages, non-food products such as pharmaceuticals and electronic components, and the like, oxygen and water vapor that permeate the packaging materials in order to suppress the deterioration of the contents and retain their functions and properties In addition, it is necessary to prevent the influence of gases that alter the contents, and it is required to have gas barrier properties that block these gases.

  Therefore, conventional gas barrier layers include metal foils typified by aluminum, resin films such as polyvinyl alcohol and ethylene vinyl alcohol copolymers, polyvinylidene chloride, polyacrylonitrile, or plastic films coated with these resins. It has been mainly used.

  However, metal foil and metal vapor-deposited film have excellent gas barrier properties, but the contents cannot be confirmed through the packaging material, metal detectors cannot be used for inspection, and they must be treated as non-combustible materials when discarded after use. There are problems such as unavoidable. Gas barrier resin films and films coated with them are highly temperature and humidity dependent and cannot maintain high gas barrier properties. Furthermore, vinylidene chloride, polyacrylonitrile, etc. may be a source of harmful substances when discarded or incinerated. There are some problems. In other words, it can be said that the gas barrier wrapping materials that are currently used mainly have various problems.

Patent documents are shown below.
As a technology for solving such a problem, a water-soluble polymer and one or more kinds of metal alkoxides or metal alkoxide hydrolysates or tin chloride are used as a first layer of a vapor deposition layer made of an oxidized inorganic compound. There has been proposed a gas barrier packaging material in which a gas barrier coating formed by applying a coating agent mainly containing an aqueous solution containing at least one of the above or a hydroalcoholic mixed solution and heating and drying is sequentially laminated as a second layer (Patent Document 1). reference). This gas barrier packaging material exhibits high gas barrier properties, water resistance and moisture resistance, and can withstand a certain amount of external stress. However, since the second coating layer of the gas barrier packaging material is composed of hydrogen bonds between the metal alkoxide hydrolyzate and a water-soluble high molecule having a hydroxyl group, the coating layer when used for packaging materials that require treatment such as boil and retort sterilization. Since the layer swells, the barrier properties are slightly deteriorated.

  The present invention is intended to solve the above-mentioned problems of the prior art, and since it is excellent in transparency, the contents can be seen through, a metal detector can be used, and a causative substance that pollutes the environment is used. Of course, an object is to provide a gas barrier film laminate that has a high gas barrier property under high temperature and high humidity and is optimal as a packaging material that maintains the barrier property even after boil or retort sterilization treatment.

  In order to achieve the above object, the invention according to claim 1 is the ultrathin piece 1 having a thickness of nanoscale size, with a vapor deposition layer made of an oxidized inorganic compound as a first layer on one or both sides of a base material made of a plastic material. A gas barrier coating layer is formed by applying a solution in which silicon dioxide having micro secondary particles having a laminated structure in which a plurality of secondary particles are stacked in parallel and a water-soluble polymer having a hydroxyl group is mixed, and drying by heating. A gas barrier film laminate comprising a second layer and sequentially laminated.

  The invention according to claim 2 is the gas barrier film laminate according to claim 1, wherein the micro secondary particles have a thickness of 0.01 to 1.0 mm and a surface diameter of 1 to 0 mm.

  A third aspect of the present invention is the gas barrier film laminate according to the first or second aspect, wherein the micro secondary particles are leaf-shaped or scale-shaped.

  According to a fourth aspect of the present invention, the solid content blending ratio of the silicon dioxide and the water-soluble polymer is within the range of the silicon dioxide / water-soluble polymer = 20/80 to 80/20 by weight ratio. It is a gas barrier film laminated body of any one of Claims 1 thru | or 3 characterized by the above-mentioned.

  The invention according to claim 5 is characterized in that a primer layer made of acrylic polyol, isocyanate, or silane coupling agent is provided between one or both sides of the substrate and a vapor deposition layer made of an inorganic compound. 5. The gas barrier film laminate according to any one of 4 above.

  Invention of Claim 6 apply | coats the mixture of the said silicon dioxide and a water-soluble polymer directly on the one or both surfaces of the said base material, and heat-drys, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. It is a gas barrier film laminated body as described in above.

A seventh aspect of the present invention is the gas barrier film laminate according to any one of the first to sixth aspects, wherein a heat seal layer is provided on the gas barrier coating layer side.
<Action>
According to the present invention, on one or both sides of a base material made of a plastic material, a vapor deposition layer made of an oxidized inorganic compound is used as the first layer, and a plurality of ultrathin primary particles having a nanoscale size are overlapped in parallel. A gas barrier coating layer formed by applying a solution in which silicon dioxide having micro secondary particles of a laminated structure and a water-soluble polymer having a hydroxyl group is mixed and heat-dried is used as the second layer, and the layers are sequentially laminated. The gas barrier property is exhibited, and the gas barrier coating layer is insolubilized. Further, if the solid content of the silicon dioxide is 50 to 80% by weight with respect to the total solid content, it has a high water-resistant barrier property that does not deteriorate even in severe processing such as boil / retort sterilization treatment. Adhesion is better if there is a primer layer made of either acrylic polyol, isocyanate, or silane coupling agent between one or both surfaces and the vapor-deposited layer composed of an oxidized inorganic compound, even if there is no vapor-deposited layer composed of an oxidized inorganic compound However, by providing a heat seal layer on the gas barrier coating layer side that exhibits high gas barrier properties, it has very good suitability when evaluated as a more practical packaging material, and provides a highly practical packaging material be able to.

  As described above, according to the present invention, it is possible to create a barrier film having high gas barrier properties, maintaining barrier properties even after boil / retort sterilization treatment, and having good adhesion properties. Use it for post-processing such as printing, dry lamination, melt extrusion lamination, thermocompression lamination, etc., and provide packaging materials with a wide range of practical use that can be used for packaging foods and beverages, pharmaceuticals, non-food products such as electronic components, etc. Is possible.

  The present invention will be described in more detail with reference to the drawings. FIG. 1 is a cross-sectional view illustrating a gas barrier film laminate of the present invention. First, FIG. 1 illustrates the gas barrier film laminate of the present invention. A substrate 1 in FIG. 1 is a substrate made of a plastic material. Next, a primer layer 2, a vapor deposition layer 3 made of an oxidized inorganic compound, and a gas barrier coating layer 4 are sequentially laminated.

  The base material 1 mentioned above consists of a plastic material, Preferably it is transparent. For example, polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin films such as polyethylene and polypropylene, polystyrene films, polyamide films such as 6,6-nylon, polycarbonate films, polyacrylonitrile films, polyimide films, etc. An engineering plastic film or the like is used, which may be stretched or unstretched, and preferably has mechanical strength and dimensional stability. Of these, a film that is arbitrarily stretched in the biaxial direction is preferably used, and when it is used as a packaging material, it is biaxial in consideration of gas barrier properties, filling suitability, texture, easy disposal, and price. A stretched polyamide film and a polyester film are preferable, and a polyester film (PET) film is more preferable.

  The thickness of the substrate 1 is not particularly limited, but considering suitability as a packaging material and processability, it is practically in the range of 3 to 200 μm, and more preferably 6 to 30 μm. .

  In addition, various well-known additives and stabilizers such as antistatic agents, plasticizers, lubricants, antioxidants, and the like may be used on the surface of the substrate 1, and in order to improve adhesion, As pretreatment, corona treatment, plasma treatment, ozone treatment, or the like may be performed, and further chemical treatment or solvent treatment may be performed. In particular, the plasma treatment is preferable because the adhesion between the substrate surface and the vapor deposition layer 3 made of the oxidized inorganic compound to be laminated next is strengthened.

In addition, when the primer layer 2 is provided between the base material 1 and the vapor deposition layer 3, the vapor deposition layer made of an oxidized inorganic compound is uniformly formed to improve the barrier property, and the adhesion is also greatly improved. When processing etc., it is preferable to provide a primer layer. The primer layer
An organic polymer obtained by a two-component reaction of an isocyanate compound with a polyol such as an acrylic polyol, polyvinyl acetal, polyester polyol or polyurethane polyol, or an organic compound having a urea bond by reaction with a polyisocyanate compound and water, polyethyleneimine or Derivatives, polyolefin emulsions, polyimides, melamines, phenols, inorganic silicas such as organically modified colloidal silica, organic silane compounds such as silane coupling agents and hydrolysates thereof, etc. Although it can be used as a primer agent, a combination of an acrylic polyol, an isocyanate compound, and a silane coupling agent is particularly preferable. In general, it is desirable to coat so that the thickness after drying is in the range of 0.005 to 5 μm, and more preferably in the range of 0.01 to 1.0 μm. When the thickness is 0.01 μm or less, it is difficult to obtain a uniform coating film from the viewpoint of coating technology.

  The vapor deposition layer 2 made of an oxide inorganic compound as the first layer is made of an oxide such as silicon, aluminum, titanium, zirconium, tin, magnesium, a unit of nitrogen or fluoride, or a composite thereof. It is formed by a vacuum process such as sputtering or plasma vapor deposition. In particular, aluminum oxide is colorless and transparent, excellent in water resistance by boil / retort sterilization treatment, and can be used for a wide range of applications.

  The film thickness of the vapor deposition layer 3 varies depending on the application and the film thickness of the second layer, but is preferably in the range of several tens to 5,000 mm. However, if the thickness is less than 50 mm, there is a problem in the continuity of the thin film. Since it is easy to generate | occur | produce and a flexibility falls, Preferably it is 50-3000cm.

  The gas barrier coating layer 4 of the present invention comprises a silicon dioxide compound having microsecondary particles having a laminated structure in which a plurality of ultrathin primary particles having a nanoscale size are overlapped in parallel, and a water-soluble high-molecular weight having a hydroxyl group. It must be formed by applying a mixed solution of molecules and drying by heating.

  The micro secondary particles are scaly and form a thin film according to the shape, but the coating itself tends to be hard. In addition, the metal oxide as the vapor deposition layer is also hard, and cracks are likely to occur due to distortion due to volume reduction during condensation. Therefore, 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 to prevent cracks by adding a polymer. However, even if the addition of the polymer is visually uniform, it is often microscopically separated into the silicon dioxide and the polymer part, and the barrier wrapping material tends to be a barrier hole. Therefore, by adding a polymer having a hydroxyl group, the silicon dioxide is well dispersed between the polymer and a high barrier property. In addition, it has already been reported that by laminating this film on a vapor-deposited layer made of an oxidized inorganic compound, the gas barrier property, water resistance, and moisture resistance are much higher than the effects obtained by each single layer.

  Further, the solid content of the silicon dioxide is 50 to 80% by weight based on the total solid content in consideration of water resistance necessary for boil / retort sterilization treatment, high barrier properties and flexibility due to coating flexibility as a packaging material. It is desirable that

  In the present invention, the water-soluble polymer having a hydroxyl group in the gas barrier coating layer is preferably polyvinyl alcohol, starch, or cellulose. In particular, when polyvinyl alcohol (hereinafter referred to as PVA) is used for the coating agent of the present invention, the gas barrier property is most excellent. Because PVA is a polymer containing the most hydroxyl groups in the monomer unit, it has a very strong hydrogen bond with the remaining silanol groups. PVA as used herein is generally obtained by saponifying polyvinyl acetate, and saponification of saponification is a complete saponification in which only several percent of acetyl groups remain from so-called partially saponified PVA. Includes up to PVA. The molecular weight of PVA has various degrees of polymerization ranging from 300 to several thousand, but there is no problem in the effect even if any molecular weight is used. However, it can be said that PVA having a molecular weight having a high degree of saponification and a high degree of polymerization is generally preferable because of high water resistance.

  The thickness of the mixed coating solution after drying is not particularly limited. However, if the thickness exceeds 50 μm or more, cracks are likely to occur. Therefore, the thickness is preferably 0.01 to 50 μm.

  As a gas barrier film layer forming method, a normal coating method can be used. For example, a dipping method, a roll coat, a gravure coat, a reverse coat, an air knife coat, a comma coat, a die coat, a silk screen, a spray coat, a gravure offset method and the like can be used. Using these coating methods, coating is performed on the deposited layer or directly on the substrate.

  Any method can be used for drying the gas barrier coating layer by heating the gas barrier coating layer such as hot air drying, hot roll drying, high frequency induction heating, infrared irradiation, UV irradiation, etc. Two or more of these may be combined.

By providing a heat seal layer on the gas barrier film side of the present invention, a more practical packaging material can be provided. The heat seal layer is used for an adhesive part when forming a bag-like package or the like, for example, polyethylene, linear polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, Resins such as ethylene-methacrylic acid ester copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, and metal cross-linked products thereof are used. The thickness is determined according to the purpose, but is generally in the range of 15 to 200 μm. Moreover, you may provide a heat seal layer in the base material side with the shape of a package.

  As a method of forming the heat seal layer, a dry laminate method in which a film made of the above-described resin is bonded using a two-component reaction curable adhesive, a non-solvent laminate method in which a non-solvent adhesive is bonded, Any method such as an extrusion laminating method in which a resin is melted by heating and extruded and bonded in a curtain shape can be formed by a known laminating method.

  A printing layer can be laminated on the gas barrier coating layer as necessary, and a plurality of resins can be laminated via an adhesive. A plurality of resins can be laminated on the opposite surface of the substrate 1 via a printing layer, a heat seal layer, and an adhesive.

The gas barrier film laminate of the present invention will be described with specific examples.
<Example 1>
A primer layer was provided on a PET substrate that had been subjected to corona treatment having a thickness of 12 μm by a gravure coater so that the film thickness was 0.1 μm. A thin film layer having a film thickness of 150 mm was formed by vacuum deposition using an electron beam heating method using aluminum oxide as a deposition source, and the following coating agent (A) was further applied by a bar coater. The film was dried for 30 minutes to form a film with a film thickness of about 0.3 μm to obtain a gas barrier film laminate.
(A) Scale-like silicon dioxide / PVA = 50/50 (% by weight)
<Example 2>
In Example 1, the gas barrier film laminated body was obtained like Example 1 except having used the following coating agent (B).
(B) Scaly silicon dioxide / PVA = 80/20 (% by weight)
Hereinafter, comparative examples of the present invention will be described.
<Comparative Example 1>
The coating agent (C) was evaluated in the same manner as in the examples.
(C) General spherical silicon dioxide / PVA = 50/50 (% by weight)
Furthermore, 70 μm-thick unstretched polypropylene (CPP) is laminated on the coating layer surface of the obtained gas barrier film laminate using an adhesive (A515 / A50 manufactured by Mitsui Takeda Chemical Co., Ltd.) to laminate the gas barrier film. Created the body. The obtained gas barrier film laminate was subjected to a retort treatment at 121 ° C. for 30 minutes, and the oxygen permeability before and after the retort treatment was measured at 30 ° C. using an oxygen permeability measuring device (OXTRAN-2 / 20 manufactured by Modern Control). Measurement was performed under an atmosphere in 70% RH.

From Table 1, it can be seen that the comparative example has a significant difference in gas barrier properties as compared to the example. Further, in the oxygen permeability after the retort treatment, the oxygen permeability after the retort is greatly deteriorated in the comparative example. On the other hand, the examples show a high barrier property without greatly deteriorating the barrier even after the retort.

  The gas barrier film laminate of the present invention is used in the packaging field of foods, beverages, non-foods such as pharmaceuticals and electronic components, etc., and maintains the particularly high gas barrier properties, so that the contents from oxygen and water vapor in the atmosphere It can be suitably used as a packaging material that blocks deterioration and deterioration.

It is sectional drawing which shows an example of a structure of the gas barrier film laminated body of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material layer 2 ... Primer layer 3 ... Deposition layer 4 ... Gas barrier film layer

Claims (7)

  A two-layer microscopic structure in which a vapor-deposited layer made of an inorganic oxide compound is used as the first layer on one or both sides of a base material made of a plastic material, and a plurality of ultrathin primary particles with a nanoscale size are stacked in parallel. A gas barrier film comprising a gas barrier coating layer formed by coating a solution in which silicon dioxide having secondary particles and a water-soluble polymer having a hydroxyl group are mixed, followed by drying by heating, as a second layer. Laminated body.   2. The gas barrier film laminate according to claim 1, wherein the micro secondary particles have a thickness of 0.01 to 1.0 μm and a surface diameter of 1 to 10 μm.   The gas barrier film laminate according to claim 1 or 2, wherein the micro secondary particles are leaf-like or scale-like.   The solid content blending ratio of the silicon dioxide and the water-soluble polymer is in the range of the silicon dioxide / water-soluble polymer = 20/80 to 80/20 in terms of weight ratio. 4. The gas barrier film laminate according to any one of 3 above.   The primer layer which consists of either an acrylic polyol, an isocyanate, or a silane coupling agent is provided between the one or both surfaces of the said base material, and the vapor deposition layer which consists of an oxidized inorganic compound, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. 2. The gas barrier film laminate according to claim 1.   5. The gas barrier film according to claim 1, wherein the mixture of the silicon dioxide and the water-soluble polymer is directly applied to one surface or both surfaces of the base material, and is heated and dried. Laminated body.   The gas barrier film laminate according to any one of claims 1 to 6, wherein a heat seal layer is provided on the gas barrier coating layer side.