JP2017177590A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide laminated film which has no anisotropy with respect to a measurement surface of gass barrier permeability and is excellent in gas barrier property exhibition on high-humidity condition.SOLUTION: There is provided a laminated film in which a metal oxide layer and a protective layer are laminated in this order on at least one surface of a polyamide base material film through or without through another layer, where the protective layer is obtained from a resin composition for protective layer that contains an urethane resin in which 50 mol% or more of the total of a polyisocyanate component is composed of m-xylene diisocyanate and/or a hydrogenated m-xylene diisocyanate component, as a component.SELECTED DRAWING: None

Description

  The present invention relates to a laminated film used in the field of packaging foods, pharmaceuticals, industrial products and the like. Specifically, it is a laminated film comprising a metal oxide layer and a protective layer, which can enhance the interlayer adhesion of the metal oxide layer, and has good gas barrier properties and adhesion even when exposed to high humidity ( The present invention relates to a laminated film capable of exhibiting (laminate strength).

  Packaging materials used for foods, pharmaceuticals, etc. should have the property of blocking gases such as oxygen and water vapor, that is, gas barrier properties, in order to prevent protein and fat oxidation, maintain taste and freshness, and maintain the efficacy of pharmaceuticals. It has been demanded. Further, gas barrier materials used for electronic devices such as solar cells and organic EL, electronic components, and the like require higher gas barrier properties than packaging materials such as food.

  Conventionally, in food applications that require blocking of various gases such as water vapor and oxygen, the surface of a base film made of plastic is an inorganic film made of a metal thin film made of aluminum or the like, or an inorganic oxide such as silicon oxide or aluminum oxide. A gas barrier laminate in which a thin film is formed is generally used. Among them, those formed with an inorganic oxide thin film (metal oxide layer) such as silicon oxide, aluminum oxide, and a mixture thereof are widely used because they are transparent and the contents can be confirmed.

  However, since the above gas barrier laminate is likely to be locally heated in the formation process, the substrate is damaged, or decomposition or degassing occurs in a low molecular weight portion or a portion of an additive such as a plasticizer. As a result, defects, pinholes, etc. may occur in the metal oxide layer and the gas barrier property may be lowered. In addition, the metal oxide layer cracks and cracks occur during post-processing of packaging materials such as printing, laminating, bag making, and the gas barrier properties are lowered. This is probably because the adhesion between the plastic substrate and the metal oxide layer was not good, and cracks occurred because the metal oxide layer could not follow the deformation of the film substrate.

  As a method for improving the defect of the gas barrier laminate having a metal oxide layer, an attempt has been made to further provide a layer having gas barrier properties on the metal oxide layer. For example, there is a method of laminating a gas barrier resin composition comprising an ethylene-vinyl alcohol copolymer and a gas barrier resin composition comprising an inorganic layered compound and an additive (see, for example, Patent Document 1). This method greatly improves the defects and gas barrier properties of the metal oxide layer.

  However, the above method has a problem that the gas barrier property is remarkably lowered under high humidity conditions. Further, the gas barrier permeability is anisotropic, and is unsuitable for development in food applications where it is necessary to suppress both the inflow of external moisture and the outflow of internal moisture. Therefore, as an example of imparting to the laminate a gas barrier property under high humidity and a gas barrier property without gas barrier permeability anisotropy, a water-soluble polymer and an inorganic layered compound and a metal alkoxide or its hydrolysis are formed on the metal oxide layer. There has been proposed a method of coating a material and forming a composite of an inorganic material containing an inorganic layered compound and a water-soluble polymer on a metal oxide layer by a sol-gel method (see, for example, Patent Document 2). According to this method, the gas barrier property under high humidity is excellent, but the stability of the liquid used for the coating is low, so the coating starts and ends (for example, industrially distributed roll film). The outer peripheral part and inner peripheral part of the roll), the characteristics differ due to slight differences in drying and heat treatment in the film width direction, and the quality varies greatly depending on the manufacturing environment. I had a problem. Furthermore, since the film coated by the sol-gel method is poor in flexibility, it has been pointed out that when a film is subjected to bending or impact, pinholes and cracks are likely to occur and gas barrier properties may be lowered. .

  Against this background, an improvement that can form a resin layer on the metal oxide layer by a coating method that does not involve a sol-gel reaction, that is, a resin that mainly contains a resin and that involves a crosslinking reaction during coating is desired. It was rare. As such a gas barrier laminate having been improved, a gas barrier laminate in which a barrier resin containing a silane coupling agent is coated on an inorganic thin film is disclosed (for example, Patent Document 3).

Japanese Patent No. 5434341 JP 2000-43182 A Japanese Patent No. 3441594

  However, in the above-described method, the gas barrier properties such as oxygen and water vapor cannot be satisfied and the gas barrier properties cannot be sufficiently maintained.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a protective layer made of a polyurethane dispersion composition is formed on a laminated film in which at least a metal oxide layer is provided on both sides or one side of a base film. As a result, the present inventors completed the present invention by finding a laminated film having good gas barrier properties under high humidity and having no gas barrier permeability anisotropy.

  The gas barrier film of the present invention has the following aspects.

  (1) A metal oxide layer and a protective layer are laminated in this order with or without other layers on at least one surface of a polyamide base film, and the protective layer is 50 mol% of the total polyisocyanate component. The laminated film obtained from the resin composition for protective layers which uses the urethane resin comprised by the metaxylene diisocyanate and / or hydrogenated metaxylene diisocyanate component as a structural component above.

(2) The laminated film according to (1), wherein the oxygen permeability under conditions of 23 ° C. × 90% RH is 10 [ml / m ² · d · MPa] or less.

(3) Water vapor permeability when water vapor permeates from the base film side under 40 ° C. × 90% RH condition and water vapor permeability when water vapor permeates from the protective layer side are both 2 g / m ^2. -The laminated film as described in said (1) or (2) which is below.

  (4) Any of the above (1) to (3) having a coating layer formed from a coating solution containing a water-dispersible acrylic graft polyester resin between the polyamide base film and the metal oxide layer A laminated film according to 1.

  (5) The laminated film according to any one of (1) to (4), wherein the metal oxide layer is a layer made of a composite oxide of silicon oxide and aluminum oxide.

  According to the present invention, there is provided a laminated film that exhibits excellent gas barrier properties (barrier properties against oxygen and water vapor) not only under low humidity but also under high humidity and has no anisotropy with respect to the measurement surface of gas barrier permeation. it can.

  As a result, the laminated film according to the present invention is also useful as a packaging film for foods, pharmaceuticals, industrial products and the like that require gas barrier properties.

  The laminated film of the present invention is obtained by laminating a metal oxide layer and a protective layer in this order on one side or both sides of a base film with or without other layers. Hereinafter, a base film and each layer laminated | stacked on this are demonstrated in order.

[Base film]
Examples of the polyamide resin used in the present invention include nylon 6 using ε-caprolactam as a main raw material. Examples of other polyamide resins include polyamide resins obtained by polycondensation of lactams having three or more members, ω-amino acids, dibasic acids and diamines. Specifically, as lactams, in addition to the above-mentioned ε-caprolactam, enantolactam, capryllactam, lauryllactam, and ω-amino acids include 6-aminocaproic acid, 7-aminoheptanoic acid, 9- Examples include aminononanoic acid and 1,1-aminoundecanoic acid. Dibasic acids include adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecadioic acid, hexadecadioic acid, eicosandioic acid, eicosadienedioic acid, 2 2,4-trimethyladipic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and xylylenedicarboxylic acid. Furthermore, as diamines, ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, pentamethylenediamine, undecamethylenediamine, 2,2,4 (or 2,4,4) -trimethylhexamethylenediamine, cyclohexane Examples thereof include diamine, bis- (4,4′-aminocyclohexyl) methane, and metaxylylenediamine. And polymers obtained by polycondensation of these or copolymers thereof, such as nylon 6, 7, 11, 12, 6.6, 6.9, 6.11, 6.12, 6T, 6I, MXD6 (Metaxylene dipanamid 6), 6 / 6.6, 6/12, 6 / 6T, 6 / 6I, 6 / MXD6, and the like can be used. In addition, when the polyamide resin laminated film roll before vapor deposition of the present invention is produced, the above polyamide resins can be used alone or in admixture of two or more.

  As the base film, those having an arbitrary film thickness can be used according to desired purposes and applications such as mechanical strength and transparency, and the film thickness is not particularly limited, but is usually 5 to 100 μm. Is recommended, and when used as a packaging material, it is preferably 8 to 60 μm. The transparency of the base film is not particularly limited, but when used as a packaging material that requires transparency, a film having a light transmittance of 50% or more is desirable.

  The base film may be a single layer film made of a polyamide resin, or may be a laminated film in which a polyamide resin layer and other plastic films (may be two or more types) are laminated. . As long as there is a polyamide resin layer, the type of laminate in the case of a laminated film is not particularly limited, and can be arbitrarily selected from known methods according to the purpose.

Moreover, in this invention, in order to improve the interlayer adhesiveness of a metal oxide layer and a polyamide base material, a desired surface treatment layer can be previously provided as needed.
In the present invention, as the surface treatment layer, for example, corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, oxidation treatment using chemicals, etc. For example, a corona treatment layer, an ozone treatment layer, a plasma treatment layer, an oxidation treatment layer, or the like can be formed and provided. The above-mentioned surface pretreatment is carried out as a method for improving the close adhesion between various resin films and metal oxide vapor-deposited films, but as a method for improving the above-mentioned close adhesion, For example, on the surface of various resin films, a primer coat agent layer, an undercoat agent layer, an anchor coat agent layer, an adhesive layer, a vapor deposition anchor coat agent layer, or the like is arbitrarily formed and coated. It can also be a layer.

[Coating layer]
In order to improve the adhesion strength between the base material layer and the metal oxide deposition layer by forming the coating layer, it is preferable to use a water-based polyester resin from the viewpoint of cost and hygiene. Such a polyester resin can be obtained by polycondensation of dicarboxylic acid or tricarboxylic acid and glycols. Examples of the components used for the polycondensation include acid components such as terephthalic acid, isophthalic acid, adipic acid, and trimellitic acid, and glycol components such as ethylene glycol, neopentyl glycol, butanediol, and ethylene glycol-modified bisphenol A. However, of course, it is not limited to these. The polyester resin may be a graft copolymerized acrylic monomer.

  The preferable thickness of the coating layer is 0.01 to 10 μm, more preferably 0.02 to 5 μm. If the thickness is less than 0.01 μm, the effect of improving the adhesion strength tends not to be sufficiently exhibited. Even if the thickness is excessively exceeded, no further improvement in adhesion is exhibited, which is disadvantageous economically.

[Metal oxide layer]
In the laminated film of the present invention, a metal oxide layer is laminated above the coating layer. The metal oxide layer is a thin film made of an inorganic oxide. The material for forming the metal oxide layer is not particularly limited as long as it can be formed into a thin film, but from the viewpoint of gas barrier properties, silicon oxide (silica), aluminum oxide (alumina), a mixture of silicon oxide and aluminum oxide (composite oxidation) Inorganic oxides such as In particular, a composite oxide of silicon oxide and aluminum oxide is preferable from the viewpoint that both flexibility and denseness of the thin film layer can be achieved. In this composite oxide, the mixing ratio of silicon oxide and aluminum oxide is preferably such that Al is in the range of 20 to 70% by mass ratio of metal. When the Al concentration is less than 20%, the barrier property may be lowered. On the other hand, when the Al concentration exceeds 70%, the metal oxide layer tends to be hard, and the film is formed during secondary processing such as printing and lamination. There is a possibility that the barrier property is lowered due to the destruction. The silicon oxide referred to here is various silicon oxides such as SiO and SiO ₂ or a mixture thereof, and the aluminum oxide is various aluminum oxides such as AlO and Al ₂ O ₃ or a mixture thereof.

  The film thickness of the metal oxide layer is usually 1 to 100 nm, preferably 5 to 50 nm. If the film thickness of the metal oxide layer is less than 1 nm, it may be difficult to obtain satisfactory gas barrier properties. On the other hand, even if the thickness exceeds 100 nm excessively, the corresponding effect of improving gas barrier properties is This is disadvantageous in terms of bending resistance and manufacturing cost.

The method for forming the metal oxide layer is not particularly limited. For example, a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, an ion plating method, or a chemical vapor deposition method (CVD method) is known. An evaporation method may be employed as appropriate. Hereinafter, a typical method for forming a metal oxide layer will be described using a silicon oxide / aluminum oxide thin film as an example. For example, when the vacuum deposition method is employed, a mixture of SiO ₂ and Al ₂ O ₃ or a mixture of SiO ₂ and Al is preferably used as a deposition material. As these vapor deposition raw materials, particles are usually used. At this time, the size of each particle is desirably such that the pressure during vapor deposition does not change, and the preferred particle diameter is 1 mm to 5 mm. For heating, methods such as resistance heating, high frequency induction heating, electron beam heating, and laser heating can be employed. It is also possible to introduce reactive vapor deposition using oxygen, nitrogen, hydrogen, argon, carbon dioxide gas, water vapor or the like as a reactive gas, or using means such as ozone addition or ion assist. Furthermore, the film forming conditions can be arbitrarily changed, for example, by applying a bias to the deposition target (laminated film to be deposited) or heating or cooling the deposition target. Such a vapor deposition material, reaction gas, bias of the deposition target, heating / cooling, and the like can be similarly changed when a sputtering method or a CVD method is employed.

[Protective layer]
The laminated film of this invention has the protective layer formed from the resin composition for protective layers explained in full detail above the said metal oxide layer.
The metal oxide layer is not a completely dense film but is dotted with minute defects. By coating a specific protective layer resin composition described later on the metal oxide layer to form a protective layer, the resin in the protective layer resin composition penetrates into the missing portion of the metal oxide layer, As a result, an effect that gas barrier properties are stabilized is obtained. Furthermore, by covering the metal oxide layer with a protective layer, the metal oxide layer can be protected from rubbing and slippage in printing processing, as well as protecting the metal oxide layer from the pigment in the ink and providing barrier properties. It becomes possible to maintain stably. In addition, by using a material having a gas barrier property for the protective layer itself, the gas barrier performance of the laminated film is greatly improved.

(Resin composition for protective layer)
The protective layer resin composition is obtained from a urethane resin containing meta-xylene diisocyanate and / or hydrogenated meta-xylene diisocyanate as a main component of the polyisocyanate component. At this time, when the ratio of the metaxylene diisocyanate and / or hydrogenated metaxylene diisocyanate component in the urethane resin to the whole polyisocyanate component is 50 mol% or more, good gas barrier properties can be exhibited.

  The urethane resin is obtained by reacting the following polyisocyanate component (A) with the following polyol component (B) by an ordinary method so that the amount of metaxylene diisocyanate and / or hydrogenated metaxylene diisocyanate component falls within the above range. It is done. Furthermore, chain extension is performed by reacting a low molecular weight compound having two or more active hydrogens such as a diol compound (for example, 1,6-hexanediol) or a diamine compound (for example, hexamethylenediamine) as a chain extender. Is also possible. In addition, “Takelac (registered trademark) WPB” series commercially available from Mitsui Chemicals, Inc. can also be used as a suitable water-based urethane resin.

(A) Polyisocyanate component Examples of the polyisocyanate component (A) that can be used for the synthesis of the urethane resin include aromatic polyisocyanate, alicyclic polyisocyanate, and aliphatic polyisocyanate. As the polyisocyanate compound, a diisocyanate compound is usually used.

  Examples of the aromatic diisocyanate include tolylene diisocyanate (2,4- or 2,6-tolylene diisocyanate or a mixture thereof) (TDI), phenylene diisocyanate (m-, p-phenylene diisocyanate or a mixture thereof), 4,4. '-Diphenyl diisocyanate, 1,5-naphthalene diisocyanate (NDI), diphenylmethane diisocyanate (4,4'-, 2,4'-, or 2,2'-diphenylmethane diisocyanate or mixtures thereof) (MDI), Examples include 4,4′-toluidine diisocyanate (TODI) and 4,4′-diphenyl ether diisocyanate. Examples of the araliphatic diisocyanate include xylene diisocyanate (1,3- or 1,4-xylene diisocyanate or a mixture thereof) (XDI), tetramethylxylene diisocyanate (1,3- or 1,4-tetramethylxylene diisocyanate or (Mixtures thereof) (TMXDI), ω, ω′-diisocyanate-1,4-diethylbenzene and the like.

  Examples of the alicyclic diisocyanate include 1,3-cyclopentene diisocyanate, cyclohexane diisocyanate (1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate), 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (iso Holodiisocyanate, IPDI), methylene bis (cyclohexyl isocyanate) (4,4'-, 2,4'- or 2,2'-methylene bis (cyclohexyl isocyanate)) (hydrogenated MDI), methylcyclohexane diisocyanate (methyl-2,4) Cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate), bis (isocyanatomethyl) cyclohexane (1,3- or 1,4-bis (iso Anetomechiru) cyclohexane or a mixture thereof) (it may be mentioned hydrogenated XDI) and the like.

  Examples of the aliphatic diisocyanate include trimethylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate (tetramethylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate), hexamethylene. Examples include diisocyanate, pentamethylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl caffeate.

(B) Polyol compound As the polyol component (particularly the diol component), low molecular weight glycols to oligomers can be used, but usually from the viewpoint of gas barrier properties, alkylene glycol (for example, ethylene glycol, propylene glycol, trimethylene glycol). 1,3-butanediol, 1,4-butanediol, pentanediol, hexanediol, neopentylglycol, heptanediol, octanediol, etc., linear or branched C _2-10 alkylene glycol), (poly) Low molecular weight glycols such as oxy C _2-4 alkylene glycol (diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, etc.) are used. The preferred glycol component is a C _2-8 polyol component [eg, C _2-6 alkylene glycol (particularly ethylene glycol, 1,2- or 1,3-propylene glycol, 1,4-butanediol, 1,6-hexane). Diol, 3-methyl-1,5-pentanediol, etc.], di- or trioxy C _2-3 alkylene glycol (diethylene glycol, triethylene glycol, dipropylene glycol, etc.), and particularly preferred diol components are C _2-8 alkylene. Glycol (especially C _2-6 alkylene glycol).

These diol components can be used alone or in combination of two or more. Further, if necessary, an aromatic diol (for example, bisphenol A, bishydroxyethyl terephthalate, catechol, resorcin, hydroquinone, 1,3- or 1,4-xylene diol or a mixture thereof), an alicyclic diol (for example, Low molecular weight diol components such as hydrogenated bisphenol A, xylylene diol, cyclohexanediol, cyclohexanedimethanol, etc.) may be used in combination. Furthermore, if necessary, a tri- or higher functional polyol component, for example, a polyol component such as glycerin, trimethylolethane, or trimethylolpropane can be used in combination. The polyol component preferably contains at least a C _2-8 polyol component (particularly C _2-6 alkylene glycol). C _2-8 polyol component of the polyol component in 100% by weight (in particular, C _2-6 alkylene glycol) ratio of may be selected from the range of about 50 to 100 wt%, typically at least 70 to 100 mass% More preferably, it is 80 mass% or more and 100 mass% or less, More preferably, it is 90 mass% or more and 100 mass% or less.

(Properties of urethane resin)
The acid value of the urethane resin is preferably in the range of 10 to 60 mgKOH / g. More preferably, it is in the range of 15 to 55 mgKOH / g, and further preferably in the range of 20 to 50 mgKOH / g. When the acid value of the urethane resin is within the above range, the protective layer can maintain flexibility while partially cross-linking, and can further improve the cohesive strength and relieve the stress of the metal oxide.

  When forming a protective layer with the resin composition for protective layers, the coating liquid (coating liquid) which consists of the said polyurethane resin, ion-exchange water, and a water-soluble organic solvent should be prepared, and it should just apply | coat and dry to a base film. As the water-soluble organic solvent, alcohols such as ethanol and isopropyl alcohol (IPA), or single or mixed solvents selected from ketones such as acetone and methyl ethyl ketone can be used, from the viewpoint of coating film processing and odor. Is preferably IPA.

  The coating method of the protective layer resin composition is not particularly limited as long as it is a method of coating the film surface to form a layer. For example, usual coating methods such as gravure coating, reverse roll coating, wire bar coating, and die coating can be employed.

The coating amount when applying the protective layer resin composition is not particularly limited, but is preferably in the range of 0.05 to 1.0 g / m ^{2 in} a dry state, and is 0 from the viewpoint of practicality. A range of 0.1 to 0.5 g / m ² is more preferable. If it is less than 0.05 g / m ^2, sufficient adhesion and gas barrier properties, protective effect is difficult to obtain, tend to be economically disadvantageous if it exceeds 1.0 g / m ^2.

  When forming the protective layer, it is preferable to heat-dry after applying the protective layer resin composition, and the drying temperature at that time is preferably 110 to 190 ° C, more preferably 130 to 190 ° C, still more preferably. Is 170-190 degreeC. When the drying temperature is less than 110 ° C., the protective layer may be insufficiently dried, or the crosslinking of the protective layer may not proceed, and the water resistance of the protective layer may decrease when subjected to normal adhesion and retort treatment. There is a risk of doing. On the other hand, if the drying temperature exceeds 190 ° C., the film may be excessively heated, and the film may become brittle, or may shrink and deteriorate processability. In addition to drying, adding an additional heat treatment (for example, 150 to 190 ° C.) is also effective in promoting the crosslinking of the protective layer.

  About the laminated film which apply | coated the resin composition for protective layers, it estimates as follows about not having humidity dependence. In general, a urethane resin exhibits gas barrier properties due to an agglomeration effect due to a hydrogen bond component of a urethane bond. However, under high humidity, the hydrogen bonding force is weakened, and the gas barrier property is lowered due to the weakening of the cohesive force. The protective layer resin composition used in the present invention is a urethane resin mainly composed of metaxylene diisocyanate and / or hydrogenated metaxylene diisocyanate, and has a stacking effect due to metaxylene groups in addition to hydrogen bond aggregation due to urethane bonds. There is also agglomeration. It is estimated that the stacking effect due to the metaxylene group is not affected by humidity, so that the humidity dependency is reduced.

  Further, the laminated film coated with the protective layer resin composition is a laminated film having no anisotropy with respect to the gas barrier permeation measurement surface. The following estimation is also made here. When a protective layer that exhibits gas barrier properties due to the cohesive effect of hydrogen bonding components such as urethane bonds is applied on the vapor deposition layer, oxygen is transmitted in the order of the vapor deposition layer and the protective layer when oxygen is permeated from the base film side. To do. At this time, moisture is blocked by the vapor deposition layer, and oxygen passing through the protective layer permeates in a low humidity state, so that the gas barrier property is improved. However, when oxygen permeates from the protective layer side, oxygen permeates in the order of the protective layer and the deposited layer. At this time, oxygen passing through the protective layer permeates in a high humidity state, so that the gas barrier property of the protective layer is lowered. For the above reasons, anisotropy of the gas barrier permeation with respect to the measurement surface occurs. On the other hand, when a urethane resin mainly composed of metaxylene diisocyanate and / or hydrogenated metaxylene diisocyanate is applied on the vapor deposition layer, the protective layer is less dependent on humidity, so that either the base film side or the protective layer side It is estimated that anisotropy of the gas barrier permeation with respect to the measurement surface does not occur even when oxygen is permeated from the surface.

[Other layers]
In addition to the base film, coating layer, metal oxide layer, and protective layer, the laminated film of the present invention may be provided with various layers provided by a laminated film having a known gas barrier property, if necessary. Can do.
For example, when the laminated film of the present invention is used as a packaging material, it preferably includes a heat-sealable resin layer called a sealant. The heat-sealable resin layer is usually provided on the metal oxide layer side, but may be provided on the outer side of the base film (the surface opposite to the coating layer forming surface). The heat-sealable resin layer is usually formed by an extrusion lamination method or a dry lamination method. The thermoplastic polymer for forming the heat-sealable resin layer may be any one that can sufficiently exhibit sealant adhesive properties, such as polyethylene resins such as HDPE, LDPE, LLDPE, polypropylene resin, and ethylene-vinyl acetate copolymer. , Ethylene-α-olefin random copolymers, ionomer resins and the like can be used.

  Furthermore, the laminated film of the present invention has at least one printed layer or other plastic substrate and / or paper substrate between or outside the metal oxide layer or substrate film and the heat-sealable resin layer. You may laminate | stack above.

  As the printing ink for forming the printing layer, aqueous and solvent-based resin-containing printing inks can be preferably used. Examples of the resin used in the printing ink include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures thereof. For printing inks, known antistatic agents, light blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, antifoaming agents, crosslinking agents, antiblocking agents, antioxidants, etc. These additives may be included. The printing method for providing the printing layer is not particularly limited, and a known printing method such as an offset printing method, a gravure printing method, or a screen printing method can be used. For drying the solvent after printing, known drying methods such as hot air drying, hot roll drying, and infrared drying can be used.

  On the other hand, as other plastic substrates and paper substrates, paper, polyester resins, biodegradable resins, and the like are preferably used from the viewpoint of obtaining sufficient rigidity and strength of the laminate. Moreover, when setting it as the film excellent in mechanical strength, stretched films, such as a biaxially stretched polyester film, are preferable.

  The laminated film of the present invention as described above exhibits excellent gas barrier properties not only under low humidity but also under high humidity, and becomes a laminated film having no anisotropy with respect to the measurement surface of gas barrier permeation. Further, even when printing is performed, the metal oxide layer is not damaged and becomes a laminated film that can achieve both printing properties such as gas barrier properties and design properties.

EXAMPLES Next, although this invention is demonstrated in detail using an Example and a comparative example, naturally this invention is not limited to a following example. Unless otherwise specified, “%” means “% by mass”, and “part” means “part by mass”.
The evaluation method used in the present invention is as follows.

<Preparation of laminate laminate A for evaluation>
A polyurethane adhesive (TM569 manufactured by Toyo Morton Co., Ltd.) was applied on the vapor deposition surface of the obtained film on the laminates obtained in Examples and Comparative Examples so that the thickness after drying at 80 ° C. was 3 μm. Thereafter, a low density polyethylene film (L4102 manufactured by Toyobo; thickness 40 μm; LL) is dry-laminated on a metal roll heated to 60 ° C., and subjected to aging at 40 ° C. for 4 days, thereby providing a laminate gas barrier property for evaluation. A laminate (hereinafter sometimes referred to as “laminate laminate A”) was obtained.

<Oxygen permeability evaluation method>
About the laminated laminate A produced above, according to JIS-K7126 B method, using an oxygen permeability measuring device (“OX-TRAN (registered trademark) 1/50” manufactured by MOCON), temperature 23 ° C., humidity 65 The oxygen permeability was measured under an atmosphere of ˜90% RH. The oxygen permeability was measured in the direction in which oxygen permeates from the base film side of the laminate laminate to the heat sealable resin layer (low density polyethylene) side.

<Evaluation method of water vapor transmission rate>
About the laminated laminate A produced above, according to JIS-K7129 B method, using a water vapor permeability measuring device ("PERMATRAN-W (registered trademark) 3 / 33MG" manufactured by MOCON), temperature 40 ° C, humidity 90 The water vapor permeability was measured under an atmosphere of% RH. The water vapor permeability was measured in the direction in which water vapor permeates from the base film side of the laminate to the heat sealable resin layer and in the direction in which water vapor permeates from the heat sealable resin layer to the base film layer.

<Method for evaluating laminate strength>
The laminate laminate A produced above was cut out to a width of 15 mm and a length of 200 mm to obtain a test piece. Under the conditions of a temperature of 23 ° C. and a relative humidity of 65%, Tensilon Universal Material Testing Machine (“Tensilon UMT- II-500 type ") was used to measure the laminate strength (normal state). In addition, the measurement of the laminate strength was performed at a tensile rate of 200 mm / min, and water was applied between the laminated film layers and the heat-sealable resin layers obtained in the examples and comparative examples to peel at a peeling angle of 90 degrees. When strength was measured.

Example 1
(1) Preparation of coating liquid 1 used for coating layer “AGN201” (solid content 25%) manufactured by Takemoto Yushi Co., Ltd. was prepared as a water-dispersible acrylic graft polyester resin containing self-crosslinkable maleic anhydride as a graft chain. .
Each material was mixed with the following compounding ratio, and the coating liquid 1 (composition for coating layer formation) was produced.
Water 33%
Isopropanol 7%
60% water-dispersible acrylic graft polyester resin

(2) Preparation of Coating Liquid 2 Used for Protective Layer A commercially available metaxylylene group-containing urethane resin dispersion (“Takelac (registered trademark) WPB341” manufactured by Mitsui Chemicals, Inc .; solid content 25%) was prepared. The acid value (theoretical value) of this urethane resin was 25 mgKOH / g. Moreover, the ratio of the metaxylylene diisocyanate with respect to the whole polyisocyanate component measured by < ¹ > H-NMR was 85 mol%.
Each material was mixed with the following mixture ratio, and the coating liquid 2 (resin composition for protective layers) was produced.
30% water
Isopropanol 30%
40% polyurethane dispersion

(3) Manufacture of polyamide base film and coating of coating liquid 1 (lamination of coating layers)
Polycaproamide was heated and melted to 260 ° C. with a screw extruder, extruded into a sheet form from a T-die, and then this unstretched sheet was stretched 3.3 times longitudinally at 80 ° C. between a heating roll and a cooling roll. . And the said coating liquid 1 was apply | coated to the single side | surface of the obtained uniaxially stretched film by the fountain bar coat method. Next, it is led to a tenter, stretched 4.0 times in the transverse direction at 120 ° C., heat-set at 215 ° C., and a biaxially stretched polyamide film (Ny) having a thickness of 15 μm has a coating layer of 0.750 g / m ^2. A formed laminated film was obtained.

(4) Formation of metal oxide layer A composite oxide layer of silicon dioxide and aluminum oxide was formed as a metal oxide layer on the coating layer forming surface of the film obtained in (3) above by an electron beam evaporation method. As the evaporation source, particulate SiO ₂ (purity 99.9%) and Al ₂ O ₃ (purity 99.9%) of about 3 mm to 5 mm were used. Here, the composition of the composite oxide layer was SiO ₂ / Al ₂ O ₃ (mass ratio) = 66/33. The film thickness of the metal oxide layer (SiO ₂ / Al ₂ O ₃ composite oxide layer) in the film (metal oxide layer / coating layer-containing film) thus obtained was 13 nm. Thus, the vapor deposition film provided with the coating layer and the metal oxide layer was obtained.

(5) Coating of vapor deposition film with coating liquid 2 (laminate of protective layer)
The coating liquid 2 prepared in the above (2) was applied on the metal oxide layer of the deposited film obtained in (4) by the gravure roll coating method and dried at 190 ° C. to obtain a protective layer. The coating amount after drying was 0.30 g / m ² (Dry).
As described above, a laminated film provided with a coating layer / metal oxide layer / protective layer on a base film was produced. About the obtained laminated | multilayer film, as above-mentioned, oxygen permeability, water vapor permeability, and laminate strength were evaluated. The results are shown in Table 2.

Example 2
A laminated film was produced in the same manner as in Example 1 except that the coating layer was not formed, and the oxygen permeability, water vapor permeability, and laminate strength were evaluated. The results are shown in Table 2.

Comparative Example 1
A laminated film was produced in the same manner as in Example 1 except that the protective layer was not formed, and the oxygen permeability, water vapor permeability, and laminate strength were evaluated. The results are shown in Table 2.

Comparative Example 2
(Preparation of gas barrier resin composition used in Comparative Example 2)
<Preparation of ethylene-vinyl alcohol copolymer solution>
In a mixed solvent of 20.996 parts of purified water and 51 parts of n-propyl alcohol (NPA), an ethylene-vinyl alcohol copolymer (trade name: Soarnol (registered trademark) V2603, manufactured by Nippon Synthetic Chemical Co., Ltd., ethylene-vinyl acetate co Polymer obtained by saponification of polymer, ethylene ratio 26 mol%, vinyl acetate component saponification degree about 100%, hereinafter abbreviated as EVOH) 15 parts are added, and further hydrogen peroxide solution with a concentration of 30% 13 parts and 0.004 part of FeSO ₄ were added, heated to 80 ° C. with stirring, and allowed to react for about 2 hours. Thereafter, the mixture was cooled and catalase was added to 3000 ppm to remove residual hydrogen peroxide, whereby an almost transparent ethylene-vinyl alcohol copolymer solution (EVOH solution) having a solid content of 15% was obtained.

<Preparation of inorganic layered compound dispersion>
4 parts of montmorillonite (trade name: Kunipia (registered trademark) F, manufactured by Kunimine Kogyo Co., Ltd.), an inorganic layered compound, was added to 96 parts of purified water with stirring, and the pressure was set sufficiently at 50 MPa with a high-pressure dispersing device. Distributed. Thereafter, the mixture was kept at 40 ° C. for 1 day to obtain an inorganic layered compound dispersion having a solid content of 4%.

<Additives>
Zirconium chloride (Daiichi Rare Element Chemical Co., Ltd., trade name: Zircosol (registered trademark) ZC-20, solid content 20%)

<Preparation of coating solution 3 used for protective layer>
31.75 parts of the EVOH solution was added to 62.30 parts of the mixed solvent A (a solvent comprising 40% purified water and 60% n-propyl alcohol), and the mixture was sufficiently stirred and mixed. Further, 5.95 parts of the inorganic layered compound dispersion was added to this solution while stirring at high speed. Cations are removed after adding 3 parts of cation exchange resin to 100 parts of this mixed solution and stirring for 1 hour at a stirring speed that does not cause crushing of the ion exchange resin. Only the resin was filtered off with a strainer.
The mixed solution obtained from the above operation was further subjected to dispersion treatment at a pressure of 50 MPa with a high-pressure dispersion apparatus, and then 0.75 part of zirconium hydrochloride and 97.sup.2 parts of mixed solvent A2. 25 parts was added, mixed and stirred, and filtered through a 255 mesh filter to obtain a protective layer coating solution 3 having a solid content of 5%.

In the same manner as in Example 1, a coating layer and a metal oxide layer were formed on a polyamide base film, and the protective layer (adhesion amount after drying) was formed on the metal oxide layer using the protective layer coating solution 3. 0.30 g / m ² ) was formed to obtain a laminated film. The obtained film was evaluated for oxygen permeability, water vapor permeability and laminate strength. The results are shown in Table 2.

The laminated film of the present invention is useful in the field of packaging foods, pharmaceuticals, industrial products and the like.

Claims (5)

  On at least one side of the polyamide base film, a metal oxide layer and a protective layer are laminated in this order with or without other layers, and the protective layer contains 50 mol% or more of the total polyisocyanate component. A laminated film obtained from a protective layer resin composition comprising a urethane resin composed of xylene diisocyanate and / or hydrogenated meta-xylene diisocyanate component. ^2. The laminated film according to claim 1, wherein the oxygen permeability under a condition of 23 ° C. × 90% RH is 10 [ml / m ² · d · MPa] or less. Water vapor permeability when water vapor permeates from the substrate film side under 40 ° C. × 90% RH condition and water vapor permeability when water vapor permeates from the protective layer side is 2 [g / m ² · d] The laminated film according to claim 1 or 2, wherein:   The laminated film according to any one of claims 1 to 3, further comprising a coating layer formed from a coating solution containing a water-dispersible acrylic graft polyester resin between the polyamide base film and the metal oxide layer. The laminated film according to any one of claims 1 to 4, wherein the metal oxide layer is a layer made of a composite oxide of silicon oxide and aluminum oxide.