Packaging film manufacturing method and packaging film

Abstract

To provide a heat-sealable vapor-deposited film having a good printed layer formed thereon without laminating a film (printed film) prepared by printing in a separate process, by forming a printed layer using an aqueous ink on the vapor-deposited layer side of the vapor-deposited film (packaging film) including a heat-sealable layer. [Solution] The present invention provides a method for producing a packaging film. The packaging film comprises a substrate layer having heat-sealability, a vapor-deposited film including a vapor-deposited layer provided on one surface of the substrate layer, and a printed layer provided on a printing surface of the vapor-deposited film, which is the surface of the vapor-deposited layer side. The production method includes a printing surface modification step of increasing the wetting tension of the printing surface to 36 mN / m or more, and a printing step of forming the printed layer on the printing surface after the printing surface modification step by printing with an aqueous ink.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a packaging film and a packaging film. [Background technology]

[0002] Vapor-deposited films such as aluminum vapor-deposited films are sometimes used as packaging films for foods such as snacks, instant noodles, and frozen foods (see, for example, Patent Documents 1 and 2). Vapor-deposited films are excellent in barrier properties against oxygen and water vapor, light-blocking properties, and design properties (metallic luster). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Jikko No. 61-2036 [Patent Document 2] Japanese Patent Application Publication No. 7-125133 Summary of the Invention [Problem to be solved by the invention]

[0004] When a design is applied to a package using a vapor-deposited film including a base layer (heat-sealable layer) having heat-sealability, it is common to prepare a laminated film by laminating a film to which a design has been applied in advance by printing or the like (printed film) onto the vapor-deposited layer side of the vapor-deposited film, and then use the laminated film to prepare a package (see Patent Documents 1 and 2). The base layer side of the vapor-deposited film is heat-sealed when the package is made, so it is necessary to apply a design to the vapor-deposited layer side of the vapor-deposited film, but it is generally difficult to print directly with ink on the surface of the vapor-deposited layer side (vapor-deposited surface).

[0005] However, environmental considerations have led to calls for a reduction in the amount of plastic used (reducing CO2 emissions). From the perspective of environmental impact, it is desirable to apply designs by direct printing using ink, rather than laminating a separate printed film with a design, and it is particularly desirable to use water-based ink, which has a lower environmental impact. Direct printing also reduces the number of manufacturing steps compared to laminating a separate printed film.

[0006] In recent years, the use of water-based inks has increased due to their low environmental impact and the improved working environment for workers. However, there has been a problem in that it is difficult to improve the adhesion of the ink when printing on the vapor-deposited layer side of vapor-deposited film.

[0007] An object of the present invention is to provide a heat-sealable vapor-deposited film having a good printed layer formed thereon, without laminating a film (printed film) prepared by printing in a separate process, by forming a printed layer using an aqueous ink on the vapor-deposited layer side of the vapor-deposited film (packaging film) including a heat-sealable layer. [Means for solving the problem]

[0008] The present invention is a method for producing a packaging film. The packaging film includes a base layer having heat-sealability, a vapor-deposited film including a vapor-deposited layer provided on one surface of the base layer, and a printing layer provided on a printing surface, which is the surface of the vapor-deposited film facing the vapor-deposited layer. The manufacturing method includes: A printing surface modification step of increasing the wet tension of the printing surface to 36 mN / m or more; and a printing step of forming the printing layer on the printing surface after the printing surface modification step by printing with a water-based ink. [Effects of the Invention]

[0009] According to the present invention, by forming a printed layer using an aqueous ink on the vapor deposition layer side of a vapor deposition film (packaging film) that includes a heat seal layer, it is possible to provide a heat sealable vapor deposition film that has a good printed layer formed thereon without laminating a film (printed film) that has been printed in a separate process. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing an example of a packaging film according to an embodiment. [Figure 2] FIG. 3 is a cross-sectional view showing another example of the packaging film of the embodiment. [Figure 3] FIG. 1 is a schematic diagram illustrating an example of a water-based flexographic printing press. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings, in which the same or common parts are designated by the same reference numerals.

[0012] Before describing the method for producing a packaging film of this embodiment, the packaging film produced by the production method of this embodiment will be described with reference to FIG.

[0013] <Packaging film> As shown in FIG. 1, the packaging film 1 of this embodiment includes a vapor-deposited film 2 and a printed layer 32. The packaging film 1 of this embodiment is a film used as a material for packaging (bags, etc.) for food, etc. Details of the packaging film 1 will be described below.

[0014] [Vapor-deposited film] The vapor-deposited film 2 includes a substrate layer 21 and a vapor-deposited layer 22 provided on one surface of the substrate layer 21. The vapor-deposited layer 22 provided on one surface of the substrate layer 21 may be provided directly on the one surface of the substrate layer 21, or may be provided via an anchor coat layer or the like.

[0015] (deposited layer) The vapor-deposited layer 22 of the vapor-deposited film 2 is a layer formed by vapor-depositing a metal, metal oxide, or the like onto the base layer 21.

[0016] Although various metals can be used as the metal, aluminum is preferably used because it is inexpensive, can provide a metallic design with its metallic luster, and also has light-blocking properties. That is, the vapor-deposited film 2 is preferably a film on which aluminum is vapor-deposited (aluminum vapor-deposited film). Examples of metal oxides include the versatile aluminum oxide (AlOx), silicon oxide (SiOx), etc. In addition to these, various organic compounds, inorganic compounds, etc. can also be used as the material for the deposition layer 22.

[0017] The deposition method is not particularly limited, but examples thereof include vacuum deposition, which is a physical deposition method, and CVD (chemical vapor deposition), which is a chemical deposition method.

[0018] The thickness of the vapor deposition layer 22 is not particularly limited as long as it can exhibit the desired properties such as light blocking, moisture resistance, and gas barrier properties, but is preferably 5 to 100 nm, and more preferably 20 to 70 nm in the case of aluminum vapor deposition.

[0019] (base material layer) The base layer 21 is made of, for example, a resin film. The resin used as the material for the resin film is preferably a thermoplastic resin. The resin film may be stretched or unstretched. Stretched resin films, such as biaxially stretched films and films uniaxially stretched in the machine direction, have dimensional stability and rigidity and are excellent in mechanical suitability for printing, bag making, etc., but are difficult to obtain heat-sealing properties, so unstretched films, which have excellent heat-sealing properties (thermal welding properties), are more suitable.

[0020] The base layer 21 has heat-sealing properties. By heat-sealing the substrate layer 21 side (opposite the vapor-deposited layer 22) of the vapor-deposited film 2 facing each other as the heat-sealing surface, a package such as a packaging bag can be produced using the packaging film 1 of this embodiment. The base layer 21 of the vapor-deposited film 2 may be composed of, for example, a heat-sealable sealant film (single layer or multiple layers obtained by co-extrusion). In this case, the processing step of laminating a separate sealant film or heat-sealing agent is unnecessary, and the number of films required to be laminated can be reduced, which simplifies the manufacturing process, reduces the cost of film materials, and enables the overall thickness of the laminated film to be reduced.

[0021] Examples of heat-sealable vapor-deposited films 2 (where the base layer 21 has heat-sealability) include films such as aluminum-deposited non-oriented polypropylene (VMCPP), aluminum-deposited heat-sealable biaxially oriented polypropylene (VMOPP), aluminum-deposited linear low-density polyethylene (VMLLDPE), aluminum-deposited high-density polyethylene (VMHDPE), and aluminum-deposited low-density polyethylene (VMLDPE). That is, examples of materials for the base layer 21 having heat-sealability include resins that can be used as sealant films, such as polypropylene (PP) such as homopolypropylene and propylene-ethylene copolymer, linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), and low-density polyethylene (LDPE).

[0022] Films made of polypropylene or polyethylene resins, which are used as the base layer 21 (sealant film) with heat sealability, generally tend to have low wettability (wet tension, wetting index), which indicates the adhesion of printing ink, and it has been confirmed that the surface of the vapor-deposited film facing the vapor-deposited layer 22 also sometimes has low wettability (wet tension less than 36 mN / m).It has also been confirmed that water-based inks have difficulty adhering to the printed surface (vapor-deposited layer) of a vapor-deposited film with such low wettability. In this embodiment, the surface (printed surface) of the vapor-deposited film 2 on which the vapor-deposited layer 22 is formed is subjected to a printing surface modification step (described later) to increase the wettability of the printed surface, which has low wettability, before the printing layer is formed. This improves the adhesion between the printed surface (vapor-deposited layer) of the vapor-deposited film and the water-based ink.

[0023] The thickness of the base layer 21 is not particularly limited, but is preferably 10 to 200 μm, and more preferably 25 to 150 μm. If the thickness of the base layer 21 (deposited film 2) is too thin, the sealing strength, rigidity, moisture resistance, etc. of the packaging film 1 may be insufficient, and if the thickness is too thick, there is a risk that the suitability for processing such as printing may be poor. From the viewpoint of reducing the amount of plastic used, it is preferable that the thickness of the vapor-deposited film 2 (substrate layer 21) be as thin as possible.

[0024] [Printing layer] The printed layer 32 is provided on the printed surface of the deposited film 2 (the surface on the deposited layer 22 side).

[0025] The print layer 32 is a layer containing a coloring material and the like that forms the design to be applied to the packaging film 1. The printed layer 32 can be formed in a single color or in multiple colors by printing using ink containing a coloring material in a position and area according to the design.

[0026] The method for forming the printed layer 32 is not particularly limited, and flexographic printing, gravure printing, letterpress printing, offset printing, etc. can be used. It is preferable to form the printing layer 32 using flexographic printing. For example, if the base layer 21 is a stretchy film such as a non-stretched film, the film is pulled during gravure printing, which may cause the film to stretch and reduce printing accuracy. Center drum flexographic printing is a relief printing method in which a film is wrapped around a drum and a flexible rubber or resin plate is used. Because the film is less likely to stretch during printing, more accurate printing is possible on stretchy films. In recent years, the use of flexographic printing using water-based inks (water-based flexographic printing) has been increasing. Compared to water-based gravure printing, water-based flexographic printing uses less ink, so it requires less energy to dry the ink, which has the advantage of being less environmentally hazardous and allowing for faster printing speeds.

[0027] (Water-based ink) In this embodiment, the ink (printing ink) used to form the printed layer 32 is a water-based ink. In recent years, environmental considerations have led to calls for a reduction in the amount of organic solvents used (especially VOCs (volatile organic compounds)). If the printed layer 32 is formed using a water-based ink that does not use organic solvents, the amount of organic solvent used can be reduced. In addition, the need for combustion treatment of VOCs can be reduced, which also leads to a reduction in CO2 emissions. In this way, water-based inks have the advantage of placing less strain on the environment than solvent-based inks.

[0028] The water-based ink contains a colorant and a water-based solvent, and may further contain a vehicle component, auxiliary components, and the like.

[0029] In this specification, an aqueous solvent is a solvent containing water as the main component (a component accounting for 50% by mass or more of the total). The aqueous solvent may contain components other than water, such as alcohol (e.g., isopropyl alcohol), but from an environmental perspective, it is preferable that the content of organic solvents is low. The proportion of water in the aqueous solvent is preferably 90% by mass or more, more preferably 95% by mass or more. The aqueous solvent may also be water alone, without any other components. When the aqueous solvent contains alcohol, the alcohol content is preferably 10% or less, more preferably 5% or less.

[0030] Colorants are materials (components) used to color printing inks. Dyes or pigments (organic or inorganic) are used as colorants. Examples of inorganic pigments include titanium oxide, red iron oxide, and extender pigments.

[0031] The vehicle component has the function of transferring and fixing the colorant in the ink to the printed material. The vehicle component may also have the function of improving the dispersibility of the colorant and improving the physical properties of the printed layer 32 (the coating film formed by printing the ink). As the vehicle component, various synthetic resins such as aqueous acrylic resins and aqueous urethane resins, and natural resins can be used.

[0032] The water-based ink preferably contains an alkali-soluble resin as the main component of the vehicle. An alkali-soluble resin is a resin that can be made water-soluble by neutralizing it with an alkali component. The alkali-soluble resin has, for example, a carboxyl group (-COOH), and can be made water-soluble by neutralizing the carboxyl group with an alkali component. The alkali-soluble resin has excellent pigment dispersibility.

[0033] Water-based inks can be prepared by dissolving alkali-soluble resins in water with volatile alkali agents such as ammonia or ethanolamine. The volatile alkali agent evaporates as the water-based ink dries (evaporates). Prints made from dried water-based ink (alkali-soluble resins) are water-resistant because they do not dissolve in neutral or acidic water.

[0034] Thus, aqueous inks obtained by solubilizing resins and the like in aqueous solvents are often alkaline, and alkaline aqueous inks have a pH of, for example, 8.5 to 9.5.

[0035] The water-based ink may be a water-based emulsion, but it is preferable that the ink contains a coloring pigment and is based mainly on an alkali-soluble resin, which is easy to adjust.

[0036] Examples of auxiliary components include silicon-based antifoaming agents, polyethylene wax as a lubricant, pigment dispersants, surfactants (leveling agents), and the like.

[0037] The thickness of the printing layer is not particularly limited, but is preferably 0.3 to 10 μm.

[0038] (Top coat layer) In the packaging film of this embodiment, the printed layer 32 and the surface of the vapor deposition layer 22 in the exposed portion where the printed layer 32 is not present (the surface opposite to the vapor deposition layer 22) may be protected by providing a top coat layer 33. The topcoat layer 33 has strength, abrasion resistance, slipperiness, etc. to protect the printed layer 32 . The top coat layer 33 preferably has transparency. The top coat layer 33 may have a glossy finish or a matte finish. In addition, it is preferable that the top coat layer 33 has heat resistance to heat sealing.

[0039] The coating agent constituting the topcoat layer 33 is not particularly limited, but examples thereof include OP (overprint) varnish. OP varnish is a transparent, translucent, or matte varnish applied to the surface of a printed layer, such as letters or a design. Unlike printing ink, it does not contain color pigments, etc., and can protect the printed surface. Varnish is a liquid paint made by dissolving or dispersing natural or synthetic resins in a solvent, and contains added abrasion-resistant materials and lubricants. Furthermore, as described above, varnishes have heat resistance to heat sealing, and in particular, some are made of curable polyurethane resins, polyester resins, polyamide resins, acrylic resins, etc., such as polyester-based polyurethanes, which are applied with a curing agent to minimize the impact on the printed layer, vapor-deposited layer, and substrate layer even when in contact with a heated heat-sealing tool.

[0040] The solvent for the varnish may be an oil-based solvent (organic solvent), but from the viewpoint of reducing the amount of organic solvent used, it is preferable that it is an aqueous solvent, i.e., the varnish is preferably an aqueous varnish.

[0041] The thickness of the topcoat layer 33 is not particularly limited, but is about 0.1 to 10 μm, and preferably 0.5 to 8 μm.

[0042] The method for forming the top coat layer 33 is not particularly limited, but the top coat layer 33 can be formed by a printing method such as flexographic printing or gravure printing, or by applying and drying a coating liquid using a roll coater or the like.

[0043] It is preferable that the printing layer 32 and the top coat layer 33 are formed by the same method. In this case, the printing layer 32 and the top coat layer 33 can be formed using a single manufacturing facility, which simplifies and improves the efficiency of the manufacturing process.

[0044] <Method of manufacturing printing film> The manufacturing method of this embodiment includes a printing surface modifying step and a printing step.

[0045] [Printing surface modification process] In the printing surface modification process, the wetting tension (wetting index) of the printing surface is increased to 36 mN / m (dyne, dyn / cm) or more (to improve wettability) before the printing process described below. By forming the printing layer after increasing the wettability of the printing surface through the printing surface modification step in this way, it is possible to improve the adhesion between the printing layer and the vapor-deposited film.

[0046] The "wet tension" is the wet tension of the printed surface before the printing layer is formed, and can be measured in accordance with JIS K 6768:1999 "Plastics - Films and sheets - Wet tension test method." "Wet tension" is also called "wetting index" or "wettability," and is sometimes referred to as "wettability" in this specification. The unit of "wet tension" is "mN / m," but dynes (dyn / cm) are sometimes used.

[0047] (Corona treatment) For example, in the printing surface modification step, the wetting tension of the printing surface (the surface of the deposition film 2 on the deposition layer 22 side) can be increased to 36 mN / m or more by subjecting the printing surface to corona treatment (corona discharge treatment).

[0048] When water-based inks are used in the printing process, corona treatment (corona discharge treatment) can be carried out near the printing process, but when solvent-based inks are used, it is difficult to carry out corona treatment near the printing process for safety reasons.

[0049] (Anchor coat layer) As another example, in the printing surface modification process, by forming an anchor coat layer 31 on the printing surface (the surface of the vapor deposition film 2 facing the vapor deposition layer 22), the wetting tension of the printing surface can be increased to 36 mN / m or more (see Figure 2).

[0050] That is, the anchor coat layer 31 has the function of making the wet tension of the printed surface of the vapor-deposited film 2 (vapor-deposited layer 22) 36 mN / m or more, and improving the adhesion of the printed layer 32 formed thereon using water-based ink. In addition, although the vapor deposition layer 22 (such as an aluminum vapor deposition layer) is vulnerable to alkaline water-based ink (it can be eroded by dissolution, etc.), the anchor coat layer 31 can also have the function of protecting the vapor deposition layer 22 from alkaline water-based ink, etc.

[0051] The anchor coat layer 31 is formed using an anchor coat agent. The anchor coating agent is preferably water-based. The water-based anchor coating agent contains, for example, a resin and an aqueous solvent. As the aqueous anchor coating agent, for example, an aqueous solution or emulsion containing a resin such as an aqueous acrylic resin or an aqueous urethane resin as a base can be used.

[0052] Examples of resins used in anchor coating agents include (meth)acrylic acid esters such as methyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; unsaturated nitriles such as (meth)acrylonitrile; polymers of one or more unsaturated amides such as (meth)acrylamide and N-methylol (meth)acrylamide; and polymers of vinyl esters such as vinyl acetate and vinyl propionate.

[0053] Resins used in anchor coating agents include acrylic and urethane resins having a structure containing a functional group that exhibits polarity, such as a carbonyl group, a carboxyl group, or a hydroxyl group, and the resins exemplified above that contain a hydrophilic resin, such as polyvinyl alcohol.

[0054] The anchor coating agent may contain an acrylic water dispersion, a vinyl acetate water dispersion, or an aqueous latex such as natural rubber latex.

[0055] Examples of commercially available water-based anchor coating agents include those sold by Sakata Inx Corporation and Toyo Ink Co., Ltd. (for example, "Aqua Anchor Varnish" by Toyo Ink Co., Ltd.).

[0056] The amount of anchor coating agent applied to the printing surface (basis weight) is, for example, 0.1 to 10 g / m 2 may be.

[0057] The pH of the anchor coating agent is preferably lower than the pH of the printing ink (water-based ink), more preferably pH 6.5 to 8.0. In this case, if the water-based ink is alkaline, the anchor coating layer 31 can prevent the deposition layer 22 from being corroded by the alkaline water-based ink.

[0058] The thickness of the anchor coat layer 31 is not particularly limited, but may be, for example, 0.1 to 10 μm.

[0059] The anchor coat layer 31 may be formed so as to cover the entire surface of the vapor deposition layer 22 used as a packaging film, but it is sufficient that it is formed at least in the area where the printed layer 32 is to be provided.

[0060] The method for forming the anchor coat layer 31 is not particularly limited, but similar to the above-mentioned printing layer 32 and top coat layer 33, the anchor coat layer 31 can be formed by a printing method such as flexographic printing or gravure printing, or by applying and drying a coating liquid using a roll coater or the like.

[0061] It is preferable that the anchor coat layer 31, the printing layer 32, and the top coat layer 33 are formed by the same method. In this case, the anchor coat layer 31, the printing layer 32, and the top coat layer 33 can be formed using a single manufacturing facility, which allows for simplification and efficiency of the manufacturing process.

[0062] (others) The modification process for improving the wettability of the printing surface is not limited to the above-mentioned corona treatment or formation of an anchor coat layer, but other methods such as plasma treatment may also be used.

[0063] [Printing process] In the printing process, a printing layer is formed on the printing surface after the printing surface modification process by printing with the above-mentioned water-based ink. Note that the printing surface referred to here means the printing surface on which the anchor coat layer 31 is provided, if the anchor coat layer 31 is provided, and the printing process also includes the case where a printing layer is formed on the anchor coat layer 31. As described above, the printing layer can be formed by, for example, flexographic printing, gravure printing, letterpress printing, offset printing, or the like, and it is preferable to use flexographic printing (aqueous flexographic printing).

[0064] [Feeding process] The manufacturing method of this embodiment may further include, for example, a feeding step of feeding out the vapor-deposited film (see FIG. 3). In this case, the printing surface modification step is preferably carried out between the feeding step and the printing step (see FIG. 3).

[0065] (Example of manufacturing process) FIG. 3 is a schematic diagram showing an example of a water-based flexographic printing press. The water-based flexographic printing press shown in Fig. 3 is a center-drum type water-based flexographic printing press including a center drum 41 and a plurality of printing units 42. Each printing unit 42 has a plate cylinder 42a and an anilox roll 42b.

[0066] The deposited film 2 is unwound from a film roll 40, which is a long strip of deposited film 2, and placed on a center drum 41 where a printing layer is formed on the printing surface (the surface on the deposited layer side) by a printing unit 42. In this manner, the unwound process and the printing process are carried out. Specifically, in the printing unit 42, ink flowing in a doctor chamber (not shown) in contact with the anilox roll 42b is scraped off with a doctor, and a fixed amount of ink according to the cell capacity of the anilox roll 42b is transferred to the raised surface of a plate (a resin flexographic printing plate attached to the circumferential surface of the sleeve of the plate cylinder) on the plate cylinder 42a. Furthermore, ink is transferred from the raised portions of the plate to the printing surface of the vapor-deposited film 2, and the transferred ink is dried in a drying chamber 43 to form a printed layer. The vapor-deposited film on which the printed layer is formed in this manner is wound onto a take-up roll 44 and stored.

[0067] In the manufacturing method of this embodiment, a printing surface modification step, such as the above-mentioned corona treatment or formation of an anchor coat layer, is carried out between the unwinding step and the printing step. When corona treatment is performed, for example, the printed surface of the vapor-deposited film 2 unwound from the film roll 40 is subjected to corona treatment in a corona unit 45 before the vapor-deposited film 2 reaches the center drum 41 . When forming an anchor coat layer, for example, an anchor coat agent is printed on the printing surface of the vapor-deposited film 2 unwound from the film roll 40 by a printing unit 421 provided at the beginning of the center drum 41, thereby forming the anchor coat layer. Note that the method for forming the anchor coat layer is not limited to this, and for example, the anchor coat layer may be formed before the printing step by a printing unit provided separately from the center drum 41.

[0068] Alternatively, the corona treatment and anchor coat layer formation (printing surface modification step) may be performed in a separate processing device, and a roll of the vapor-deposited film that has been subjected to the printing surface modification step may be arranged as the film roll 40, and printing may be performed by the flexographic printing machine on the printing surface of the vapor-deposited film 2 unwound from the film roll 40. In this case, it is preferable to print promptly (for example, within a few days) on the vapor-deposited film that has been subjected to the printing surface modification step. Furthermore, after forming an anchor coat layer on the printed surface of the vapor-deposited film 2, the surface of the anchor coat layer may be subjected to a corona treatment. Alternatively, the printed surface of the vapor-deposited film 2 on which the anchor coat layer is to be formed may be subjected to a corona treatment, and then the anchor coat layer may be formed, thereby improving the adhesion of the anchor coat layer to the vapor-deposited surface.

[0069] (packaging) The packaging film 1 can be used for packaging processing or bag-making processing (production of packaging bags). During packaging processing or bag-making processing, the surfaces of the packaging film 1 opposite to the vapor-deposited layer 22 of the vapor-deposited film 2 (the substrate layer 21 side) are placed face to face, and a heated heat seal bar or the like is pressed against the top coat side (the outermost surface of the packaging film) to heat seal the two surfaces. For example, by stacking two sheets of packaging film 1 with the base layer 21 side facing each other and heat-sealing the edges of three of the four sides of the packaging film 1, a packaging bag can be produced with the remaining side open. In addition, when the base material layer 21 has heat-sealing properties, the base material layers 21 can be heat-sealed together to produce packaging materials such as packaging bags and pillow packaging that are sealed on three sides or four sides. [Example]

[0070] <Ink adhesion test for water-based flexographic printing> (Water-based flexographic printing) Using Sakata Inx's DGS2 series water-based ink, a printing layer was formed on the printing surface (the surface facing the deposition layer) of the deposition film by water-based flexographic printing. The deposited films used were aluminum-deposited CPP (product number: MGP, Saichi Kogyo Co., Ltd.), aluminum-deposited CPP (product number: MLHS, Saichi Kogyo Co., Ltd.), or aluminum-deposited LLDPE (RM Tocello Co., Ltd.). The printed layer was formed on the printed surface after the printing surface (vapor deposition layer) was subjected to corona treatment or an anchor coat layer (acrylic resin layer) was formed to increase the wetting tension of the printed surface to the values ​​shown in Table 1. For comparison, a printed layer was also formed separately on an untreated printed surface.

[0071] <Evaluation> Each of the above-mentioned vapor-deposited films (number: 5) on which a printed layer was formed was evaluated for the following items.

[0072] (Adhesiveness) A 12mm wide piece of Scotch tape (product name, Nichiban Co., Ltd.) was applied to the printed surface, rubbed twice with a finger, and then the tape was peeled off. The printed surface was then observed for the degree of ink peeling and evaluated based on the following criteria. The evaluation results are shown in Table 1. ○: No peeling or slight peeling ×: 30% or more peeled off

[0073] (scratch resistance) The printed surface was rubbed with a fingernail. After that, the printed surface was observed for ink loss and evaluated based on the following criteria. The evaluation results are shown in Table 1. ○: Almost no dropout ×: Easily falls off

[0074] (fir resistance) The printed material (deposited film) was rubbed 10 times. After that, the printed surface was observed for ink removal and evaluated based on the following criteria. The evaluation results are shown in Table 1. ○: Almost no dropout ×: Easily falls off

[0075] (Abrasion resistance) Using a Gakushin-type rub fastness tester, the printed surface was rubbed 100 times with a weight of 500 g. After that, the print was observed for ink loss and evaluated based on the following criteria. The evaluation results are shown in Table 1. ○: Almost no dropout ×: Falling off and vapor deposition exposed

[0076] [Table 1]

[0077] The evaluation results shown in Table 1 show that the vapor-deposited film has a heat-sealable base layer (polyolefin resin film) with a vapor-deposited layer (aluminum vapor deposition) on one side. By applying a corona treatment or forming an anchor coat layer on the vapor-deposited layer side (printed surface) of the base layer, the wetting tension of the printed surface can be increased to 36 mN / m or more, thereby improving the ink adhesion (adhesion between the water-based ink and the printed surface) in water-based flexographic printing.

[0078] It is noted that when the vapor-deposited film is a vapor-deposited CPP, both the corona treatment and the anchor coat layer have the effect of increasing the wettability of the printed surface. Furthermore, when the vapor-deposited film is vapor-deposited LLDPE, the anchor coat layer tends to be more effective at increasing the wettability of the printed surface than corona treatment.

[0079] The present invention is not limited to the above-described embodiment, and can be modified in various ways. Two or more embodiments selected from the various embodiments described above may be combined as appropriate, or at least one configuration (part of a configuration) selected from the various embodiments described above may be replaced with part of a configuration of another embodiment.

[0080] <Summary> The following will exemplify the above-described embodiments of the present invention.

[0081] (1) A method for manufacturing a packaging film, comprising: the packaging film comprises a substrate layer having heat-sealability, a vapor-deposited film including a vapor-deposited layer provided on one surface of the substrate layer, and a printed layer provided on a printing surface of the vapor-deposited film that faces the vapor-deposited layer, A printing surface modification step of increasing the wet tension of the printing surface to 36 mN / m or more; A printing step of forming the printing layer by printing using an aqueous ink on the printing surface after the printing surface modification step; A manufacturing method comprising:

[0082] (2) The manufacturing method according to (1), wherein in the printing surface modification step, an anchor coat layer is formed on the printing surface to increase the wetting tension of the printing surface to 36 mN / m or more.

[0083] (3) The manufacturing method according to (1), wherein in the printing surface modification step, an anchor coat layer is formed on the printing surface to increase the wetting tension of the printing surface to 36 mN / m or more.

[0084] (4) The method further includes a step of unwinding the vapor-deposited film, The manufacturing method according to any one of (1) to (3), wherein the printing surface modifying step is carried out between the feeding step and the printing step.

[0085] a vapor-deposited film including a base layer having heat-sealability and a vapor-deposited layer provided on one surface of the base layer; and a printed layer provided on a printing surface of the vapor-deposited film that faces the vapor-deposited layer, A packaging film produced by the production method according to any one of (1) to (4). [Explanation of symbols]

[0086] 1. Packaging film 2. Vapor-deposited film 21 Base material layer 22 Deposited layer 31 Anchor coat layer 32 Printing layer 33 Topcoat layer 40 film rolls 41 Center drum 42,421 printing units 42a cylinder 42b anilox roll 43 Drying room 44 Winding roll 45 Corona Unit

Claims

1. A method for producing a packaging film, comprising: the packaging film comprises a substrate layer having heat-sealability, a vapor-deposited film including a vapor-deposited layer provided on one surface of the substrate layer, and a printed layer provided on a printing surface of the vapor-deposited film that faces the vapor-deposited layer, A printing surface modification step of increasing the wet tension of the printing surface to 36 mN / m or more; A printing step of forming the printing layer by printing using an aqueous ink on the printing surface after the printing surface modification step; A manufacturing method comprising:

2. The manufacturing method according to claim 1 , wherein the printing surface modification step includes subjecting the printing surface to a corona treatment to increase the wetting tension of the printing surface to 36 mN / m or more.

3. The manufacturing method according to claim 1, wherein in the printing surface modification step, an anchor coat layer is formed on the printing surface to increase the wetting tension of the printing surface to 36 mN / m or more.

4. The method further includes a step of unwinding the vapor-deposited film, The manufacturing method according to claim 1 , wherein the printing surface modifying step is performed between the feeding step and the printing step.

5. a vapor-deposited film including a base layer having heat-sealability and a vapor-deposited layer provided on one surface of the base layer; and a printed layer provided on a printing surface of the vapor-deposited film that faces the vapor-deposited layer, A packaging film produced by the method of claim 1.

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