JP2022026963A - Laminate film and method for producing the same, and packaging bag - Google Patents

Abstract

To provide a method for producing a laminate film having gas barrier properties which has sufficiently high laminate strength between an ink layer contained in the laminate film and a layer contacting the ink layer.SOLUTION: A method for producing a laminate film 10 includes: a step (A) of forming an ink layer 7 onto a surface a gas barrier layer 1A using aqueous liquid ink by flexographic printing; a step (B) of coating an adhesive layer so as to cover the ink layer; and a step (C) of sticking a base material layer 9 onto the adhesive layer, in which the aqueous liquid ink contains a pigment, a binder resin and a water-soluble solvent, a content of the pigment based on the total mass of the ink layer is 40-75 mass%, and in a cross section of the ink layer observed by a scanning type electrode microscope, a ratio of an area of a gap with a diameter of 0.1 μm or more to the area of the ink layer is 5% or less.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a laminated film, a method for producing the same, and a packaging bag, and more specifically, to a laminated film having a gas barrier property, a method for producing the same, and a packaging bag.

Conventionally, gas barrier laminated films having various layer configurations have been developed and marketed as packaging materials for packaging foods and the like. Such a packaging material has, for example, a layer structure in which a base film, a gas barrier layer, a printing layer, an adhesive layer, a base material, and a sealant layer are sequentially laminated.

In the field of packaging materials, de-VOC (volatile organic compounds) is being promoted as an environmental measure. That is, in order to form a printing layer such as characters, patterns, and patterns, an oil-based ink containing a solvent, which is a volatile organic compound (VOC), is converted to an ink containing no solvent. Patent Document 1 discloses an aqueous liquid ink containing a colorant, a binder having an acid group, a basic compound, and an aqueous medium. According to Patent Document 1, the water-based liquid ink described in this document is useful as an ink for gravure printing or flexographic printing.

International Publication No. 2019/102854

Gravure printing is a type of intaglio printing, in which printing is performed by transferring the ink in the recesses of the plate to the printed matter. On the other hand, flexographic printing is a kind of letterpress printing, in which ink is attached to the convex portion of the plate and transferred to the printed matter to perform printing. Gravure printing and flexographic printing each have advantages and disadvantages, and they are used properly according to the type of printed matter and the design to be expressed by printing.

Flexographic printing using letterpress is said to be inferior in color development because the amount of ink adhered to the printed matter is smaller than that of gravure printing using intaglio. As a result of the studies by the present inventors, in order to improve the color development of the ink layer by flexographic printing, when the laminated film is manufactured through the step of performing flexographic printing using an ink containing a high concentration of pigment, the laminated film is formed. It has been found that delamination is likely to occur between the layer in contact with the layer (for example, the adhesive layer).

The present disclosure has been made in view of the above problems, and is a laminated film having a gas barrier property, and a laminated film having a sufficiently high laminating strength between an ink layer contained therein and a layer in contact with the ink layer, and a production thereof. Provide a method. The present disclosure provides a package using this laminated film.

The method for producing a laminated film according to the present disclosure includes (A) a step of forming an ink layer on the surface of a gas barrier layer by using a water-based liquid ink and flexographic printing, and (B) an adhesive layer so as to cover the ink layer. The water-based liquid ink contains a pigment, a binder resin, and a water-soluble solvent, and includes a step of coating the ink layer and a step of attaching the base material layer to the adhesive layer (C), and the total mass of the ink layer. The content of the pigment is 40 to 75% by mass, and the ratio of the area of voids having a diameter of 0.1 μm or more to the area of the ink layer in the cross section of the ink layer observed by the scanning electronic microscope is It is 5% or less.

According to the above manufacturing method, although the content of the pigment in the ink layer is relatively high, the area ratio of the voids in the ink layer is sufficiently small to achieve excellent laminating strength between the ink layer and the adhesive layer. can do. The fact that the area ratio of the voids is sufficiently small means that not only the binder resin but also a part of the adhesive layer coated in the step (B) is impregnated between the particulate pigments. As a result, it is presumed that the strong adhesion between the ink layer and the adhesive layer is exhibited.

The coating liquid for coating the adhesive layer is preferably a solvent-free adhesive composition from the viewpoint of environmental friendliness. The adhesive composition may be, for example, one containing at least a polyester polyol. The weight average molecular weight of this polyester polyol is preferably 500 to 3000. When the weight average molecular weight of the polyester polyol is in the above range, the components of the adhesive layer easily permeate into the ink layer, and the laminating strength of both layers can be further increased.

The laminated film according to the present disclosure has a laminated structure including a gas barrier layer, an ink layer containing a pigment and a binder resin, and an adhesive layer made of an adhesive composition in this order, and has a total mass of the ink layer. As a reference, the pigment content is 40 to 75% by mass, and the ratio of the area of voids having a diameter of 0.1 μm or more to the area of the ink layer is 5 in the cross section of the ink layer observed by a scanning electron microscope. % Or less.

According to the laminated film, although the content of the pigment in the ink layer is relatively high, the area ratio of the voids in the ink layer is sufficiently small, so that the ink layer and the adhesive layer are excellent as described above. Laminate strength can be achieved.

The binder resin contained in the ink layer contains urethane acrylate, which is a reaction product of the polyol and polyisocyanate, and contains an acrylic acid ester in which the polyol has an alkyl group having 16 or more carbon atoms from the viewpoint of improving the heat resistance of the ink layer. Is preferable.

The gas barrier layer has, for example, a multilayer structure including a base film, a primer layer, a thin-film deposition layer, and a first gas barrier coating layer in this order. The first gas barrier coating layer is formed by using a composition containing at least one selected from the group consisting of a hydroxyl group-containing polymer compound, a metal alkoxide, a silane coupling agent, and a hydrolyzate thereof. It was done. The primer layer contains, for example, a complex of one or more selected from the group consisting of trifunctional organosilanes and hydrolysates thereof, acrylic polyols, and isocyanate compounds.

The gas barrier layer may have a multilayer structure including a base film and a second gas barrier coating layer, and the second gas barrier coating layer may contain a polycarboxylic acid-based polymer. The gas barrier layer has a multilayer structure including a base film and a third gas barrier coating layer, and the third gas barrier coating layer contains a reaction product of a metal oxide and a phosphorus compound. May be good.

The gas barrier layer is a surface opposite to the first surface of the base film having the first surface subjected to plasma treatment, the vapor-deposited layer provided on the first surface, and the first surface of the base film. It may have a multi-layer structure including a gas barrier coating layer provided on the second surface side.

One aspect of the present disclosure provides a packaging bag made by making the laminated film. This packaging bag has excellent lamination strength between the ink layer and the adhesive layer.

According to the present disclosure, there is provided a laminated film having a gas barrier property and having a sufficiently high laminating strength between an ink layer contained therein and a layer in contact with the ink layer, and a method for producing the same. According to the present disclosure, a package using this laminated film is provided.

FIG. 1 is a cross-sectional view schematically showing an embodiment of the laminated film according to the present disclosure. FIG. 2 is a cross-sectional view schematically showing an example of a packaging material containing the laminated film shown in FIG. FIG. 3 is a plan view schematically showing an embodiment of a packaging bag using the laminated film according to the present disclosure. FIG. 4 is a cross-sectional view schematically showing another example of the gas barrier layer. FIG. 5 is a cross-sectional view schematically showing another example of the gas barrier layer. FIG. 6 is a cross-sectional view schematically showing another example of the gas barrier layer. FIG. 7A is an SEM image showing a cross section of the laminated film according to Example 1, and FIG. 7B is an SEM image showing a cross section of the laminated film according to Comparative Example 1.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments. In the drawings, the same or corresponding parts are designated by the same reference numerals, and duplicate description will be omitted. The dimensional ratios in the drawings are not limited to the ratios shown.

<Laminated film>
FIG. 1 is a cross-sectional view schematically showing a laminated film according to this embodiment. The laminated film 10 shown in FIG. 1 includes a gas barrier layer 1A, an ink layer 7, an adhesive layer 8, and a base material layer 9. The ink layer 7 contains a pigment 7a and a binder resin. The content of the pigment 7a is 40 to 75% by mass based on the total mass of the ink layer 7. When this content is 40% by mass or more, an ink layer 7 having excellent color development can be formed even by flexographic printing. On the other hand, when the content is 75% by mass or less, delamination between the ink layer 7 and the adhesive layer 8 tends to be suppressed. The content of the pigment 7a (based on the total mass of the ink layer) is, for example, 45 to 75% by mass or 50 to 70% by mass from the viewpoint of achieving both excellent color development and suppression of delamination to a higher degree. May be good.

The ink layer 7 is in contact with the adhesive layer 8, and the components of the adhesive layer 8 are impregnated into the ink layer 7. Since the components of the adhesive layer 8 are soaked into the ink layer 7, in the cross section of the ink layer 7 observed by a scanning electron microscope (SEM), voids having a diameter of 0.01 μm or more with respect to the area of the ink layer 7 are formed. The area ratio is 5% or less (see FIG. 7A). On the other hand, when the content of the pigment in the ink layer is 40% by mass or more and the component of the adhesive layer is not sufficiently permeated into the ink layer, the ratio of the area of the voids becomes larger than 5% (Fig.). 7 (b)). The ratio of the area of the voids in the ink layer is determined by processing the SEM image using image analysis software (ImageJ (trade name), manufactured by the National Institutes of Health (NIH)), and the cross-sectional area and diameter of the ink layer are 0. The total area of voids of 0.01 μm or more can be obtained and calculated from these values.

The ink layer 7 may contain a plurality of types of pigments depending on the color. For example, a first ink layer containing a pigment having a relatively small particle size is formed on the surface of the gas barrier layer 1A, and then a pigment having a relatively large particle size (for example, a white pigment) is formed on the surface of the first ink layer. A second ink layer containing the above may be formed. By forming the second ink layer containing the white pigment, the color development property of the first ink layer can be further improved.

The binder resin contained in the ink layer 7 preferably contains urethane acrylate, which is a reaction product of the polyol and the polyisocyanate. From the viewpoint of improving the heat resistance of the ink layer 7, it is preferable that the polyol contains an acrylic acid ester having an alkyl group having 16 or more carbon atoms (for example, octadecyl methacrylate). When it is not necessary to impart heat resistance to the ink layer 7, the acrylic acid ester does not have to have an alkyl group having 16 or more carbon atoms. The organic components contained in the ink layer 7 can be grasped by thermal decomposition GC / MS.

The adhesive layer 8 is interposed between the ink layer 7 and the base material layer 9 and adheres these layers. Examples of the adhesive constituting the adhesive layer 8 include a polyurethane resin obtained by reacting a main agent such as a polyester polyol, a polyether polyol, an acrylic polyol, and a carbonate polyol with a bifunctional or higher isocyanate compound. The various polyols may be used alone or in combination of two or more. The adhesive layer 12 may be a polyurethane resin containing a carbodiimide compound, an oxazoline compound, an epoxy compound, a phosphorus compound, a silane coupling agent, or the like, for the purpose of promoting adhesion.

From the viewpoint of environmental friendliness, it is preferable to form the adhesive layer 8 by using a solvent-free adhesive composition. The adhesive composition may be, for example, one containing at least a polyester polyol. The weight average molecular weight of this polyester polyol is preferably 500 to 3000. When the weight average molecular weight of the polyester polyol is in the above range, the components of the adhesive layer 8 easily permeate into the ink layer, and the laminating strength of both layers can be further increased.

The total thickness of the ink layer 7 and the adhesive layer 8 is, for example, 1.5 to 6.0 μm.

The base material layer 9 may be appropriately selected depending on the use of the packaging material to which the laminated film 10 is applied. For example, when the laminated film 10 is applied to a packaging material for heat sterilization treatment (boil treatment or retort treatment), a resin film having heat resistance and water resistance is used. Specific examples of the heat-resistant water-resistant resin film include polyester film (polyethylene terephthalate, polyethylene naphthalate, etc.), polyamide film (nylon-6, nylon-66, etc.), polystyrene film, polyvinyl chloride film, polyimide film. Examples thereof include a film, a polycarbonate-based film, a polyether sulfone-based film, an acrylic-based film, and a cellulose-based film (triacetyl cellulose, diacetyl cellulose, etc.). For packaging of medical supplies, medicines, foods and the like, for example, polyethylene terephthalate or polyamide is preferably used. The thickness of these resin films may be, for example, in the range of about 6 to 200 μm. The resin film is not limited to those derived from petroleum, and is partially or partially composed of biological resin materials (for example, PLA, PBS, biomass-derived ethylene, biomass polyethylene using propylene as a raw material, biomass polypropylene or biomass polyethylene terephthalate). It may be included in all. A method for producing polyethylene derived from biomass is disclosed in, for example, Japanese Patent Publication No. 2010-511634, and a method for producing biomass polypropylene is disclosed in Japanese Patent Publication No. 2013-503647. Further, commercially available biomass polyethylene (Green PE manufactured by Braskem, etc.) may be used. Further, the resin film may contain a part or all of a biodegradable resin material (for example, polylactic acid, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, modified polyvinyl alcohol, casein, modified starch, etc.). The base film 1 may contain additives such as an antistatic agent, an ultraviolet absorber, a plasticizer, a lubricant, and a colorant.

When the laminated film 10 is applied to a packaging material that does not require high water resistance, the base material layer 9 does not necessarily have to be a resin film, and may be, for example, paper. Specific examples of the paper include high-quality paper, special high-quality paper, coated paper, art paper, cast-coated paper, imitation paper and kraft paper. The thickness (mass per unit area) of these papers may be, for example, in the range of 20 to 500 g / m ² or 25 to 400 g / m ² .

In the present embodiment, the gas barrier layer 1A has a multilayer structure, and the base film 1, the primer layer 2, the vapor deposition layer 3, and the gas barrier coating layer 5A (first gas barrier coating layer) are arranged in this order. include.

As the base film 1, the same resin film and paper as the base layer 9 described above can be used. It may be appropriately selected according to the use of the packaging material to which the laminated film 10 is applied.

The primer layer 2 is provided on the surface of the base film 1, and is intended to improve the adhesion performance between the base film 1 and the vapor-deposited layer 3. In addition to this, the primer layer 2 is intended to uniformly form the vapor-filmed layer 3 without defects by smoothing the surface on which the thin-film-deposited layer 3 is formed. When the base film 1 is paper, the primer layer 2 serves as a seal. The primer layer 2 does not necessarily have to be provided when sufficient adhesion to the vapor-filmed layer 3 can be obtained by applying the above-mentioned various pretreatments to the laminated surface of the base film 1.

Examples of the material constituting the primer layer 2 include a silane coupling agent, an organic titanate, a polyacrylic acid, a polyester, a polyurethane, a polycarbonate, a polyurea, a polyamide, a polyolefin-based emulsion, a polyimide, a melamine, and a phenol. Considering that the primer layer 2 is imparted with heat-resistant water, it is more preferable that the primer layer 2 contains an organic polymer having one or more urethane bonds and urea bonds. It is more preferable that the primer layer 2 contains one or more selected from the group consisting of trifunctional organosilanes and hydrolysates thereof, and a composite of an acrylic polyol and an isocyanate compound.

For the urethane bond and urea bond, even if a polymer introduced in the polymerization step in advance is used, an isocyanate compound having an isocyanate group with a polyol such as acrylic or methacrylic polyol, or an amine resin having an amino group and an epoxy group and a glycidyl group A urethane compound formed by reacting an epoxy compound with an isocyanate compound, or a urea bond formed by reacting an isocyanate compound with a solvent such as water or ethyl acetate, or an amine resin having an amino group is used. May be good. Of these, as the non-aqueous resin constituting the primer layer 2, a composite of an acrylic polyol, a polyester polyol, an isocyanate compound, a silane coupling agent, or the like is more preferable.

The acrylic polyol is a polymer compound obtained by polymerizing an acrylic acid derivative monomer or a polymer compound obtained by copolymerizing an acrylic acid derivative monomer with another monomer and having a hydroxyl group at the terminal. It reacts with the isocyanate group of the isocyanate compound added later. The polyester polyols include terephthalic acid, isophthalic acid, phthalic acid, methylphthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, succinic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, and methyltetrahydrophthalic acid. Acid raw materials such as hexahydrophthalic acid and reactive derivatives thereof, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-hexanediol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, A polyester-based resin obtained from alcohol raw materials such as neopentyl glycol, bishydroxyethyl terephthalate, trimethylolmethane, trimethylolpropane, glycerin, and pentaerythritol by a well-known production method and having two or more hydroxyl groups at the inner end. Then, it reacts with the isocyanate group of the isocyanate compound added later.

The isocyanate compound is added to enhance the adhesion to the base material or the inorganic oxide by the urethane bond formed by reacting with the acrylic polyol and the polyester polyol, and mainly acts as a cross-linking agent or a curing agent. In order to achieve this, the isocyanate compounds include aromatic-based toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), aliphatic-based xylene diisocyanate (XDI), hexaranged isocyanate (HMDI) and other monomers. These polymers and derivatives are used, and these are used alone or as a mixture or the like.

As the silane coupling agent, a silane coupling agent containing any organic functional group can be used, for example, ethyltrimethoxysilane, vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane. , Glysideoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, or other silane coupling agents or hydrolyzates thereof, or two or more thereof can be used.

The primer layer 2 is formed through a step of applying a coating liquid on the surface of the base film 1. As the coating method, the cast method, dipping method, roll coating method, gravure coating method, screen printing method, reverse coating method, spray coating method, kit coating method, die coating method, metering bar coating method, and chamber doctor are used together. Conventionally known methods such as a coating method and a curtain coating method can be used. The primer layer 2 is formed by heating and drying the coating film formed by applying the coating liquid. The thickness of the primer layer 2 is, for example, about 0.01 μm to 10 μm.

The thin-film deposition layer 3 is a layer on which a metal or an inorganic compound is vapor-deposited. As a material having a high oxygen gas barrier property, aluminum oxide (AlOx), silicon oxide (SiOx), magnesium fluoride (MgF ₂ ), magnesium oxide (MgO), indium-tin oxide (ITO) and the like can be used. From the viewpoint of material cost, barrier performance and transparency, aluminum oxide or silicon oxide is preferable as the material constituting the vapor deposition layer 3. The thin-film deposition layer 3 may be formed by vapor-filming aluminum.

The thickness of the thin-film deposition layer 3 may be appropriately set depending on the intended use, but is preferably 10 to 300 nm, and more preferably 20 to 200 nm. By setting the thickness of the thin-film deposition layer 3 to 10 nm or more, it is easy to make the continuity of the vapor-film deposition layer 3 sufficient, while by setting it to 300 nm or less, the occurrence of curls and cracks can be sufficiently suppressed, and sufficient barrier performance and sufficient barrier performance Easy to achieve flexibility.

The thin-film deposition layer 3 can be formed by a vacuum film-forming means. It is preferable from the viewpoint of oxygen gas barrier performance and membrane uniformity. As the film forming means, there are known methods such as a vacuum vapor deposition method, a sputtering method, and a chemical vapor deposition method (CVD method), but the vacuum vapor deposition method is preferable because the film forming speed is high and the productivity is high. Among the vacuum vapor deposition methods, the film forming means by electron beam heating is particularly effective because the film forming rate can be easily controlled by the irradiation area and the electron beam current, and the temperature of the vapor deposition material can be raised and lowered in a short time. be.

The gas barrier coating layer 5A is a coating layer having a gas barrier property, and contains at least one selected from the group consisting of a hydroxyl group-containing polymer compound, a metal alkoxide, a silane coupling agent, and a hydrolyzate thereof. It is formed by using a composition for forming a gas barrier coating layer (hereinafter, also referred to as a coating agent) containing an aqueous solution or a water / alcohol mixed solution as a main component. The coating agent preferably contains at least a silane coupling agent or a hydrolyzate thereof from the viewpoint of more sufficiently maintaining the gas barrier property after hot water treatment such as retort treatment, and is preferably a hydroxyl group-containing polymer compound, a metal alkoxide and the like. It is more preferable to contain at least one selected from the group consisting of those hydrolysates and a silane coupling agent or a hydrolyzate thereof, and a hydroxyl group-containing polymer compound or a hydrolyzate thereof, a metal alkoxide or a metal alkoxide or the like. It is more preferable to contain the hydrolyzate and the silane coupling agent or the hydrolyzate thereof. The coating agent is, for example, hydrolyzed directly or in advance of the metal alkoxide and the silane coupling agent in a solution in which a hydroxyl group-containing polymer compound which is a water-soluble polymer is dissolved in an aqueous (water or water / alcohol mixed) solvent. It can be prepared by mixing those that have undergone treatment such as alkoxide.

Each component contained in the coating agent for forming the gas barrier coating layer 5A will be described in detail. Examples of the hydroxyl group-containing polymer compound used in the coating agent include polyvinyl alcohol, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate and the like. Among these, when polyvinyl alcohol (hereinafter abbreviated as PVA) is used as a coating agent for the gas barrier coating layer 5A, it is preferable because the gas barrier property is particularly excellent.

The gas barrier coating layer 5A is formed from a composition containing at least one selected from the group consisting of a metal alkoxide represented by the following general formula (1) and a hydrolyzate thereof from the viewpoint of obtaining excellent gas barrier properties. Is preferable.
M (OR ¹ ) _m (R ² ) _nm ... (1)
In the above general formula (1), R ¹ and R ² are independently monovalent organic groups having 1 to 8 carbon atoms, and are preferably alkyl groups such as a methyl group and an ethyl group. M represents an n-valent metal atom such as Si, Ti, Al, Zr and the like. m is an integer from 1 to n. When there are a plurality of R ¹ or R ² , R ¹ or R ² may be the same or different.

Specific examples of the metal alkoxide include tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ] and triisopropoxyaluminum [Al (O-2'-C ₃ H ₇ ) ₃ ]. Tetraethoxysilane and triisopropoxyaluminum are preferred because they are relatively stable in aqueous solvents after hydrolysis.

Examples of the silane coupling agent include compounds represented by the following general formula (2).
Si (OR ¹¹ ) _p (R ¹² ) _3-p R ¹³ ... (2)
In the above general formula (2), R ¹¹ represents an alkyl group such as a methyl group or an ethyl group, and R ¹² is an alkyl group substituted with an alkyl group, an aralkyl group, an aryl group, an alkenyl group or an acryloxy group, or a methacrylate group. A monovalent organic group such as an alkyl group substituted with a group is shown, R ¹³ is a monovalent organic functional group, and p is an integer of 1 to 3. When a plurality of R ^11s or R ^12s are present, the R ^11s or the R ^12s may be the same or different from each other. The monovalent organic functional group represented by ^R13 is a monovalent organic functional group containing a glycidyloxy group, an epoxy group, a mercapto group, a hydroxyl group, an amino group, an alkyl group substituted with a halogen atom, or an isocyanate group. The group is mentioned.

Specific examples of the silane coupling agent include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-. Examples thereof include a silane coupling agent such as methacryloxypropylmethyldimethoxysilane.

Further, the silane coupling agent may be a multimer obtained by polymerizing the compound represented by the above general formula (2). As the multimer, a trimer is preferable, and 1,3,5-tris (3-trialkoxysilylalkyl) isocyanurate is more preferable. This is a condensed polymer of 3-isocyanate alkylalkoxysilane. It is known that the 1,3,5-tris (3-trialkoxysilylalkyl) isocyanurate has no chemical reactivity in the isocyanate portion, but the reactivity is ensured by the polarity of the nurate portion. Generally, it is added to an adhesive or the like like 3-isocyanate alkylalkoxylan, and is known as an adhesive improving agent. Therefore, by adding 1,3,5-tris (3-trialkoxysilylalkyl) isocyanurate to the hydroxyl group-containing polymer compound, the water resistance of the gas barrier coating layer 5A can be improved by hydrogen bonding. 3-Isocyanatealkylalkoxylan is highly reactive and has low liquid stability, whereas 1,3,5-tris (3-trialkoxysilylalkyl) isocyanurate is not water-soluble due to its polarity. However, it is easy to disperse in an aqueous solution, and the liquid viscosity can be kept stable. The water resistance is equivalent to that of 3-isocyanatealkylalkoxylan and 1,3,5-tris (3-trialkoxysilylalkyl) isocyanurate.

1,3,5-Tris (3-trialkoxysilylalkyl) isocyanurate may be produced by thermal condensation of 3-isocyanatepropylalkoxysilane, and may contain the raw material 3-isocyanatepropylalkoxysilane. However, there is no particular problem. More preferably, it is 1,3,5-tris (3-trialkoxysilylpropyl) isocyanurate, and more preferably 1,3,5-tris (3-trimethoxysilylpropyl) isocyanurate. Since this methoxy group has a high hydrolysis rate and those containing a propyl group can be obtained at a relatively low cost, 1,3,5-tris (3-trimethoxysilylpropyl) isocyanurate is practically advantageous.

If necessary, an isocyanate compound or a known additive such as a dispersant, a stabilizer, a viscosity modifier, or a colorant can be added to the coating agent as long as the gas barrier property is not impaired.

The thickness of the gas barrier coating layer 5A is preferably 50 to 1000 nm, more preferably 100 to 500 nm. When the thickness of the gas barrier coating layer 5A is 50 nm or more, more sufficient gas barrier properties tend to be obtained, and when it is 1000 nm or less, sufficient flexibility tends to be maintained.

The coating agent for forming the gas barrier coating layer 5A is, for example, a dipping method, a roll coating method, a gravure coating method, a reverse gravure coating method, an air knife coating method, a comma coating method, a die coating method, a screen printing method, and a spray coating method. , Can be applied by the gravure offset method or the like. The coating film to which this coating agent is applied can be dried by, for example, a hot air drying method, a hot roll drying method, a high frequency irradiation method, an infrared irradiation method, a UV irradiation method, or a combination thereof. The hot air drying method is most preferable for drying the coating film in consideration of high-speed processability.

<Manufacturing method of laminated film>
Next, a method for manufacturing the laminated film 10 will be described. The laminated film 10 is manufactured through the following steps.
(A) A step of forming an ink layer 7 on the surface of the gas barrier coating layer 5A in the gas barrier layer 1A by using a water-based liquid ink and flexographic printing.
(B) A step of applying the adhesive layer 8 so as to cover the ink layer 7.
(C) A step of attaching the base material layer 9 to the adhesive layer 8.

By using the water-based liquid ink in the step (A), it is possible to achieve VOC removal. By setting the pigment content to 40 to 75% by mass based on the total mass of the solid content of the water-based liquid ink, as described above, the ink layer 7 having excellent color development can be formed even by flexographic printing. .. In the step (B), by applying the adhesive composition so as to cover the ink layer 7, the adhesive layer 8 is formed in a state where the components of the adhesive composition are soaked into the ink layer 7. De-VOC can be achieved by using, for example, a solvent-free adhesive composition.

<Packaging material>
FIG. 2 is a cross-sectional view schematically showing an example of a packaging material containing the laminated film 10. The packaging material 20 shown in this figure includes a laminated film 10, a sealant layer 15, and an adhesive layer 12 for adhering them. For example, by selecting the adhesive layer 12 and the sealant layer 15 having heat resistance, the packaging material 20 can also have excellent heat resistance.

The adhesive layer 12 adheres the laminated film 10 and the sealant layer 15. As the adhesive constituting the adhesive layer 12, the same adhesive as the above-mentioned adhesive layer 8 can be used. It may be appropriately selected according to the use of the packaging material to which the laminated film 10 is applied.

As the sealant layer 15, for example, a polypropylene film having a melting point of 150 ° C. or higher may be used. As the sealant layer 15, a sealant film containing a part or all of biomass polyethylene, biomass polypropylene or biomass polyethylene terephthalate using biomass-derived ethylene, propylene or the like as a raw material may be used. Such a sealant film is disclosed in, for example, Japanese Patent Application Laid-Open No. 2013-177531.

<Packaging bag>
FIG. 3 is a plan view schematically showing an embodiment of a packaging bag using the laminated film 10. The packaging bag 30 shown in FIG. 3 is processed into a bag shape by heat-sealing the three sides L1, L2, and L3. The packaging bag 30 can be sealed by heat-sealing the opening 30a after the contents are put in through the opening 30a that is not heat-sealed. The mode of the packaging bag is not limited to this. Other examples of packaging bags include pillow packaging, three-way sealed packaging and gusset packaging.

Although the embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above embodiments. For example, in the above embodiment, the laminated film 10 having the gas barrier layer 1A shown in FIG. 1 is exemplified, but the configuration of the gas barrier layer is not limited to this, and may be those shown in FIGS. 4 to 6. The gas barrier layer 1B shown in FIG. 4 is composed of a base film 1 and a gas barrier coating layer 5B (second gas barrier coating layer). The gas barrier coating layer 5B is, for example, a layer containing a polycarboxylic acid-based polymer. The gas barrier layer 1C shown in FIG. 5 is composed of a base film 1 and a gas barrier coating layer 5C (third gas barrier coating layer). The gas barrier coating layer 5C is, for example, a layer containing a reaction product of a metal oxide and a phosphorus compound. The gas barrier layer 1D shown in FIG. 6 includes a base film 1 having a first surface 1a subjected to plasma treatment, a thin-film deposition layer 3 provided on the first surface 1a, and a first base film 1. It may have a multilayer structure including a gas barrier coating layer 5D provided on the second surface 1b side, which is the opposite surface of the surface 1a. The gas barrier coating layer 5D may be, for example, any of the gas barrier coating layers 5A to 5C.

Hereinafter, the present disclosure will be described with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

[Example 1]
<Manufacturing of gas barrier laminated film>
As a gas barrier film (gas barrier layer), GL-ARH (manufactured by Toppan Printing Co., Ltd., thickness: 12 μm) having a gas barrier coating layer on the outermost surface was prepared. A pattern ink (water-based ink layer) was laminated on the surface of the gas-barrier coating layer of this gas barrier film by water-based flexographic printing. Then, a solvent-free adhesive composition was applied onto the pattern ink to form an adhesive layer. A biaxially stretched nylon film (double-sided corona treatment, thickness: 15 μm) was attached to the adhesive layer. Next, a solvent-free adhesive layer is applied to the surface of this nylon film, and a corona-treated surface of a non-stretched polypropylene film for retort sterilization (CPP, thickness 70 μm, manufactured by Toray Film Processing Co., Ltd., trade name “ZK500”) is bonded. rice field. After curing the adhesive at 40 ° C. for 3 days, a gas barrier laminated film having the following composition was obtained. This configuration is the same as that of the laminated film 10 shown in FIG.
-Structure: Gas barrier film / water-based ink layer / solvent-free adhesive layer / ONY / solvent-free adhesive layer / CPP (thermoplastic resin layer)

As the water-based ink layer, XS911 (manufactured by DIC Corporation) was used, and four-color printing (yellow Y, magenta M, cyan C, white W) was used. The total coating amount was 1.5 g / m ² . Based on the total mass (mass of solid content) of the water-based ink layer, the pigment content was 50% by mass for YMC and 72% by mass for W. The vehicle (binder resin) of the water-based ink contained a main agent containing methyl methacrylate, ethyl 2-methylenebutate and octadecyl methacrylate, and a curing agent containing isophorone diisocyanate (IPDI). As the solvent-free adhesive layer composition, RN-800 / HN-800 (manufactured by Rock Paint Co., Ltd., containing a polyester polyol having a weight average molecular weight of 500 to 3000) was used, and the coating amount was 1.8 g / m ² . FIG. 7A is an SEM image showing a cross section of the laminated film according to the first embodiment.

<Making a packaging bag>
Two gas barrier laminated films were laminated so that their thermoplastic resin layers were in contact with each other, and heat-sealed on three sides to prepare a packaging bag having a width of 100 mm and a length of 150 mm. From the upper opening, 100 g of a mixed solution of edible vinegar: ketchup: salad oil = 1: 1: 1 was filled as the contents of the food pseudo-solution, and the upper part was heat-sealed and sealed. The heat sealing conditions were a sealing temperature of 180 ° C., a sealing time of 1 second, and a sealing pressure of 0.3 MPa.

[Example 2]
A gas barrier laminated film was produced in the same manner as in Example 1 except that PB-A (manufactured by Toppan Printing Co., Ltd.) was used as the gas barrier film instead of GL-ARH, and a packaging bag was obtained. The structure of the gas barrier film according to the second embodiment corresponds to the structure of the gas barrier layer 1B shown in FIG.

[Example 3]
A laminated film was produced in the same manner as in Example 1 except that Clarista C (manufactured by Kuraray) was used as the gas barrier film, and a packaging bag was obtained. The configuration of the gas barrier film according to the third embodiment corresponds to the configuration of the gas barrier layer 1C shown in FIG.

[Example 4]
Example 1 and the same as Example 1 except that 2K-SF-900A / 930B (manufactured by DIC Corporation, Mn = 2000) was used instead of RN-800 / HN-800 as the adhesive composition for forming the solvent-free adhesive layer. A laminated film was prepared in the same manner, and a packaging bag was obtained.

[Example 5]
A laminated film was produced in the same manner as in Example 1 except that XS903 (manufactured by DIC Corporation) was used as the water-based ink, and a packaging bag was obtained. The vehicle (binder resin) of this water-based ink contained a main agent composed of methyl methacrylate and a curing agent containing isophorone diisocyanate (IPDI).

[Comparative Example 1]
A gas barrier laminated film was produced in the same manner as in Example 1 except that the adhesive composition containing an organic solvent was used instead of forming the solvent-free adhesive layer to obtain a packaging bag. .. As the adhesive composition, A626 / A50 (Mitsui Chemicals, Inc., dry lami adhesive, molecular weight 20000) was used, and the dry coating amount was 2.8 g / m ² . FIG. 7B is an SEM image showing a cross section of the laminated film according to Comparative Example 1.

[Measurement of laminate strength]
A test piece having a width of 15 mm was cut out from the gas barrier laminated film obtained in each example, and the initial laminating strength was measured at room temperature (20 ° C., 30% RH) in accordance with JIS-K6854 using a tensile tester. did.

[Retort resistance]
After the packaging bag obtained in each example is retort-sterilized at 121 ° C. for 30 minutes, a test piece having a width of 15 mm is cut out from the packaging bag, and the laminated strength after sterilization is measured in the same manner as the initial laminating strength. did. In addition, the appearance of the packaging bag after the retort sterilization treatment was visually confirmed to confirm the presence or absence of delamination. Those without delamination were rated as "○ (good)", and those with delamination were rated as "x (poor)".

[Content resistance]
The retort-treated sample of the packaging bag obtained in each example was stored at room temperature (20 ° C., 30% RH) for half a year. The appearance of the packaging bag after storage was visually confirmed, and the presence or absence of delamination was confirmed. Those without delamination were rated as "○ (good)", and those with delamination were rated as "x (poor)".

[Organic components contained in the ink layer]
The ink layer was analyzed by thermal decomposition GC / MS. The organic components presumed to be contained in the ink layer were as follows.
(1) Examples 1 to 4 and Comparative Example 1 (ink used: XS911)
-Acrylic or acrylic monomer Methyl methacrylate, ethyl 2-methylenebutate and octadecyl isocyanate isocyanatesisophorone diisocyanate (IPDI) and phenylisocyanate-Other adipic acid and cyclic esters (caprolactone)
(2) Example 5 (ink used: XS903)
-Acrylic or acrylic monomer Methyl methacrylate Isophorone diisocyanate (IPDI) and phenyl isocyanate

1 ... Base film, 1A, 1B, 1C, 1D ... Gas barrier layer, 1a ... First surface, 1b ... Second surface, 2 ... Primer layer, 3 ... Evaporation layer, 5A, 5B, 5C, 5D ... Gas barrier Sexual coating layer, 7 ... ink layer, 7a ... pigment, 8, 12 ... adhesive layer, 9 ... substrate layer, 10 ... laminated film, 15 ... sealant layer, 20 ... packaging material, 30 ... packaging bag.

Claims (11)

(A) A process of forming an ink layer on the surface of a gas barrier layer by using a water-based liquid ink and flexographic printing.
(B) A step of applying an adhesive layer so as to cover the ink layer, and
(C) The step of attaching the base material layer to the adhesive layer and
Including
The water-based liquid ink contains a pigment, a binder resin, and a water-soluble solvent.
The content of the pigment is 40 to 75% by mass based on the total mass of the ink layer.
A method for producing a laminated film, wherein in the cross section of the ink layer observed by a scanning electron microscope, the ratio of the area of voids having a diameter of 0.1 μm or more to the area of the ink layer is 5% or less. The coating liquid for coating the adhesive layer is a solvent-free adhesive composition.
The method for producing a laminated film according to claim 1, wherein the adhesive composition contains at least a polyester polyol having a weight average molecular weight of 500 to 3000. With the gas barrier layer,
An ink layer containing a pigment and a binder resin,
An adhesive layer made of an adhesive composition and
Has a laminated structure containing in this order,
The content of the pigment is 40 to 75% by mass based on the total mass of the ink layer.
A laminated film in which the ratio of the area of voids having a diameter of 0.1 μm or more to the area of the ink layer in the cross section of the ink layer observed by a scanning electron microscope is 5% or less. The binder resin contains urethane acrylate, which is a reaction product of a polyol and a polyisocyanate.
The laminated film according to claim 3, wherein the polyol contains an acrylic acid ester having an alkyl group having 16 or more carbon atoms. The laminated film according to claim 3 or 4, wherein the gas barrier layer has a multilayer structure including a base film, a primer layer, a vapor-deposited layer, and a first gas barrier coating layer in this order. The first gas barrier coating layer is formed by using a composition containing at least one selected from the group consisting of a hydroxyl group-containing polymer compound, a metal alkoxide, a silane coupling agent, and a hydrolyzate thereof. The laminated film according to claim 5, which is the same as that of the above-mentioned film. The laminated film according to claim 5 or 6, wherein the primer layer contains one or more selected from the group consisting of trifunctional organosilanes and hydrolysates thereof, and a composite of an acrylic polyol and an isocyanate compound. The gas barrier layer has a multilayer structure including a base film and a second gas barrier coating layer.
The laminated film according to claim 3 or 4, wherein the second gas barrier coating layer contains a polycarboxylic acid-based polymer. The gas barrier layer has a multilayer structure including a base film and a third gas barrier coating layer.
The laminated film according to claim 3 or 4, wherein the third gas barrier coating layer contains a reaction product of a metal oxide and a phosphorus compound. The gas barrier layer is a base film having a first surface subjected to plasma treatment, a vapor-deposited layer provided on the first surface, and a side opposite to the first surface of the base film. The laminated film according to claim 3 or 4, which has a multilayer structure including a gas barrier coating layer provided on the second surface side, which is a surface. A packaging bag made by manufacturing the laminated film according to any one of claims 3 to 10.

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