Laminate and producing method thereof, packaging bag, as well as package

Abstract

To provide a laminate excellent in tearing property while reducing environmental load.SOLUTION: A laminate comprises a substrate film, a primer layer, an adhesive layer, and a sealant film in this order, and includes a printed surface of an electrostatic ink composition adhered to the adhesive layer. The adhesive layer contains a solvent-free adhesive composition including a polyol component and a polyisocyanate component, its cured product, or a mixture thereof, and the adhesive strength of the adhesive layer is 1.0 N / 15 mm width or more. The laminate has a group of scratches, each consisting of multiple scratches that include through-holes.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a laminate, a method for manufacturing the same, a packaging bag, and a package. [Background technology]

[0002] Packaging bags for sealing and preserving beverages, food, and the like are known. Packages made of thin films or sheets are used as packaging bags. Patent Document 1 proposes providing a large number of fine scratches penetrating the heat-sealed portion of the packaging bag so that the bag can be easily and reliably opened by hand without compromising its strength. Various information such as the product, brand, and manufacturer is printed on such packaging bags. A digital printer using an electrostatic ink composition is known as a printing method.

[0003] For example, Patent Document 2 proposes applying a primer resin to a first flexible substrate such as a PET film to obtain a coated surface, performing electrostatic printing on the coated surface using a digital printer (HP's Indigo 20000 label and packaging digital printer), and then applying a crosslinking composition. It is known that laminates containing such digitally printed electrostatic ink layers suffer from reduced adhesive strength. Therefore, Patent Document 3 proposes using a cured product of a polyol, a polyisocyanate, and an epoxy compound as an adhesive layer to produce a laminate capable of maintaining sufficiently high adhesive strength between layers even under high-temperature hot water conditions such as retort treatment.

[0004] On the other hand, from the viewpoint of reducing the environmental load, development of adhesives that do not contain organic solvents is underway. For example, Patent Document 4 proposes a two-component curing solventless adhesive containing a polyisocyanate component and a polyol component, and a composite film for packaging foods, beverages, medicines, quasi-drugs, etc. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-315055 [Patent Document 2] Special Publication No. 2018-530478 [Patent Document 3] International Publication No. 2021 / 024981 [Patent Document 4] Japanese Patent Application Laid-Open No. 2011-162656 Summary of the Invention [Problem to be solved by the invention]

[0006] Digital printing using electrostatic ink compositions allows for small-lot production, and digitally printed laminates are used as materials for various packaging bags. However, the electrostatic ink layer applied by a digital printing machine may not have sufficient adhesive strength with the primer layer or adhesive layer, raising concerns about poor tearability between the electrostatic ink layer and the primer layer or adhesive layer when external force is applied. For example, when a laminate with insufficient interlayer adhesion is torn apart, delamination may occur between the electrostatic ink layer and the primer layer or adhesive layer. This delamination occurs because the external force used to tear the laminate is not fully utilized to tear the base film. Therefore, laminates with insufficient interlayer adhesion are likely to experience delamination when torn, resulting in poor tearability. In particular, when tearing from a group of scars, as in Patent Document 1, tear resistance tends to be greater than from a notch, making tearability a problem.

[0007] On the other hand, conventional organic solvent-based adhesive layers used to adhere electrostatic ink layers use organic solvents, which raises concerns about environmental impact. Therefore, the present disclosure provides a laminate including an electrostatic ink layer that has excellent tearability while reducing environmental impact, and a method for manufacturing the same. Furthermore, the present disclosure provides a packaging bag and a packaging body including such a laminate. [Means for solving the problem]

[0008] One aspect of the present disclosure provides a laminate comprising a substrate film, a primer layer, an adhesive layer, and a sealant film, in this order, and a printed surface of an electrostatic ink composition adhered to the adhesive layer, wherein the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture of these, and the adhesive layer has an adhesive strength of 1.0 N / 15 mm width or more, and the laminate has a group of scars composed of a plurality of scars each including a through-hole.

[0009] Because electrostatic ink compositions used in digital printing machines have lower strength than other inks, the adhesive strength of the adhesive layer adjacent to the electrostatic ink layer is reduced, making it more likely to undergo delamination during tearing, which is thought to be one of the factors that deteriorates tearability. This phenomenon of deteriorated tearability is more likely to occur when a group of scars is used than when a notch is used. The above-mentioned laminate has an adhesive strength of 1.0 N / 15 mm width or more, which ensures sufficient adhesion between the adhesive layer and the electrostatic ink layer, resulting in excellent tearability even for laminates with a group of scars. Furthermore, the solvent-free adhesive layer reduces environmental impact.

[0010] One aspect of the present disclosure provides a method for producing a laminate, the method comprising the steps of: forming a primer layer on one side of a substrate film; printing an electrostatic ink composition on the primer layer to obtain a printed surface; adhering the printed surface and a substrate including a sealant film together using a solventless adhesive composition including a polyisocyanate component and a polyol component; curing or semi-curing the adhesive composition to form an adhesive layer having an adhesive strength of 1.0 N / 15 mm width or more; and forming a group of scars consisting of a plurality of scars each including a through hole.

[0011] Electrostatic ink compositions used in digital printers have lower strength than other inks, resulting in lower adhesive strength of the adhesive layer adjacent to the electrostatic ink layer, making it more susceptible to interlayer delamination during tearing. This is thought to be one of the factors that contribute to the deterioration of tearability. This phenomenon of deterioration of tearability is more likely to occur when a group of scars is used than when a notch is used. The method for manufacturing the above laminate includes a step of curing or semi-curing the adhesive composition so that the adhesive layer has an adhesive strength of 1.0 N / 15 mm width or more. This ensures sufficient adhesion between the adhesive layer and the electrostatic ink layer, and even a laminate with a group of scars has sufficiently excellent tearability. Furthermore, the use of a solvent-free adhesive layer reduces environmental impact.

[0012] One aspect of the present disclosure provides a packaging bag constructed by heat-sealing the sealant films in the above-described laminate. Because the packaging bag includes the above-described laminate, it has a solvent-free adhesive layer and the adhesive strength of the adhesive layer is sufficiently high. Therefore, it is possible to provide a packaging bag that has excellent tearability while reducing environmental impact. Furthermore, because digital printing (electrostatic printing) can be used, it is possible to produce small lots at low cost, and the degree of freedom in the design of the packaging bag can be sufficiently increased.

[0013] One aspect of the present disclosure provides a package including the above-described packaging bag and an item to be contained in the packaging bag. Because the packaging includes the above-described laminate, the adhesive layer has a solvent-free adhesive layer with sufficiently high adhesive strength. Therefore, it is possible to provide a packaging bag that reduces environmental impact and has excellent tearability. Furthermore, because digital printing (electrostatic printing) can be used, it is possible to produce small lots at low cost, and the design freedom of the package can be sufficiently increased. [Effects of the Invention]

[0014] It is possible to provide a laminate including an electrostatic ink layer that has excellent tearability while reducing the environmental impact, and a method for manufacturing the same. It is also possible to provide a packaging bag and a packaging body that include such a laminate. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a cross-sectional view showing an example of a laminate. [Figure 2] FIG. 10 is a cross-sectional view showing another example of a laminate. [Figure 3] FIG. 2 is a plan view showing an example of a packaging bag and a packaging body. [Figure 4] FIG. 10 is a perspective view showing another example of a packaging bag and a packaging body. [Figure 5] (A) is a photograph showing the packaging bag of Example 1 used to evaluate the appearance after tearing. (B) is a photograph showing the packaging bag of Example 2 used to evaluate the appearance after tearing. (C) is a photograph showing the packaging bag of Comparative Example 1 used to evaluate the appearance after tearing. [Figure 6] (A) is a photograph showing the packaging bag of Comparative Example 2 used to evaluate the appearance after tearing, and (B) is a photograph showing the packaging bag of Comparative Example 3 used to evaluate the appearance after tearing. [Figure 7] (A) is a photograph showing the packaging bag of Comparative Example 4 used in the evaluation of appearance after tearing, and (B) is a photograph showing the packaging bag of Comparative Example 5 used in the evaluation of appearance after tearing. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings as needed. However, the following embodiments are merely examples for explaining the present disclosure and are not intended to limit the present disclosure to the following content. In the description, the same elements or elements having the same functions will be designated by the same reference numerals, and redundant description will be omitted where appropriate. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the orientation of the reference numerals shown in the drawings. Furthermore, the dimensional ratios of each element are not limited to those shown in the drawings.

[0017] Unless otherwise specified, the materials exemplified in this disclosure can be used singly or in combination of two or more. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition refers to the total amount of the multiple substances present in the composition, unless otherwise specified. In this disclosure, numerical ranges indicated using "to" include the respective numerical values ​​before and after "to" as minimum and maximum values. When multiple numerical ranges are exemplified in stages, the present disclosure also includes numerical ranges in which the upper or lower limit of a first numerical range is replaced with the upper or lower limit of a second numerical range that is narrower than the first numerical range.

[0018] <Laminate> Fig. 1 is a cross-sectional view showing an example of a film-like laminate. Fig. 1 shows a cross section along the lamination direction (thickness direction) of the laminate. The laminate 300 has, in this order, a base film 10, a primer layer 40, an electrostatic ink layer 50, an adhesive layer 30, and a sealant film 20. The primer layer 40 and the electrostatic ink layer 50 are in contact with each other, and the electrostatic ink layer 50 and the adhesive layer 30 are in contact with each other.

[0019] The substrate film 10 may have a flexible substrate. The flexible substrate may be, for example, a thermoplastic polymer film. Examples of flexible substrates include biaxially oriented polypropylene (OPP), biaxially oriented polypropylene (BOPP), polyethylene terephthalate (PET), oriented polyamide (OPA), solid polypropylene (CPP), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and nylon film.

[0020] The base film 10 may include, for example, a vapor-deposited film having a resin layer such as a PET film and a barrier layer (vapor-deposited layer) on the resin layer. This can improve the sealing performance when the laminate 300 is used as a packaging material. Examples of the barrier layer include a metal foil, a vapor-deposited layer of a metal (e.g., aluminum), or a metal oxide (e.g., silica or alumina). The thickness of the base film 10 may be 7 to 150 μm, 10 to 100 μm, or 12 to 80 μm. The vapor-deposited film may be a transparent vapor-deposited film or an opaque metal vapor-deposited film. A specific example of a transparent vapor-deposited film is a transparent vapor-deposited PET film in which a transparent vapor-deposited layer is formed on a PET film. The base film 10 may include a nylon film such as a barrier nylon film.

[0021] The primer layer 40 may contain a resin. Examples of the resin include polyvinyl alcohol resin, cellulose-based resin, polyester, polyamine, polyethyleneimine resin, polyamide resin, polyurethane, polyacrylic polymer, hydroxyl-containing resin, carboxyl-containing resin, and amine-based polymer. The presence of the primer layer 40 allows smooth printing of the electrostatic ink composition using a digital printer. Furthermore, the adhesion of the electrostatic ink layer 50 to the primer layer 40 can be improved. The amount of resin applied to the primer layer 40 is, for example, 0.01 to 1.5 g / m. 2 and may be 0.05 to 1.0 g / m 2 may be.

[0022] The laminate 300 has a printing surface 52 on the primer layer 40. An electrostatic ink layer 50 is provided on the printing surface 52. The electrostatic ink layer 50 may be composed of an electrostatic ink composition. The electrostatic ink layer 50 is provided by electrostatic printing using a digital printing machine. As shown in FIG. 1 , the electrostatic ink layer 50 may be provided so as to cover a portion of one surface of the primer layer 40. In other words, the electrostatic ink layer 50 may be provided so as to be interspersed between the primer layer 40 and the adhesive layer 30. This allows the laminate 300 to have plain areas.

[0023] The electrostatic ink layer 50 may be a single color, or may be configured by laminating multiple electrostatic ink compositions of different colors. The electrostatic ink layer 50 and the adhesive layer 30 are adjacent to each other. In this example, the multiple electrostatic ink layers 50 have the same height, but this is not limited to this. The electrostatic ink layer 50 may also be multiple, or may be connected into one. In this example, a portion of the primer layer 40 is covered with the electrostatic ink layer 50 in the horizontal direction of FIG. 1. The portion not covered with the electrostatic ink layer 50 is a plain portion. In another example, the electrostatic ink layer 50 may cover the entire one side of the primer layer 40, and the adhesive layer 30 and the primer layer 40 may not have a portion where they are in direct contact (a laminate without a plain portion).

[0024] The thickness of the electrostatic ink layer 50 can be adjusted by changing the ink coverage. Ink coverage represents the ratio of halftone dot area per unit area. For example, when a predetermined area is uniformly printed with a single color, the ink coverage is 100%. On the other hand, the ink coverage of an unprinted area (plain area) is 0%. The ink coverage can be calculated based on these two values. For example, applying the electrostatic ink composition once can achieve an ink coverage of 200%, and applying it twice can achieve an ink coverage of 300%. In this way, increasing the number of times the electrostatic ink composition is applied can increase the ink coverage. Applying the electrostatic ink composition once to only half of the total area of ​​the area results in an ink coverage of 50%. When printing with multiple colors of ink, the ink coverage for each color of ink is calculated, and the sum of these values ​​can be used as the ink coverage of the printed surface.

[0025] The ink coverage is set on a digital printing press (e.g., an HP Indigo 20000 label and packaging digital printing press) and can be adjusted by specifying a desired value in the ink coverage setting. The ink coverage on the printing surface 52 can be confirmed by observing the printing surface 52 with an optical microscope.

[0026] The ink coverage may be 500% or less, 400% or less, 300% or less, or even 200% or less. Such ink coverage reduces the thickness of the electrostatic ink layer 50, further increasing the adhesive strength of the adhesive layer. Such a laminate has even better tear resistance. The ink coverage may be 10% or more, or even 100% or more.

[0027] The electrostatic ink composition that constitutes the electrostatic ink layer 50 is an ink composition used in liquid electrophotographic printing, i.e., electrostatic printing, and is printed on the primer layer 40. The electrostatic ink composition may contain a colorant or pigment, such as a dye, and a resin. In addition to these, the electrostatic ink composition may also contain a carrier fluid or carrier liquid. It may also contain a charge director, a charge adjuvant, a surfactant, a viscosity modifier, an emulsifier, and other additives. It may also contain a component that permeates through the adhesive layer 30 (e.g., a polyisocyanate component).

[0028] Examples of colorants include cyan pigments, magenta pigments, yellow pigments, and black pigments. To facilitate digital printing, resins with relatively low melting points (e.g., 100°C or less) can be used. Examples of resins include thermoplastic resins such as ethylene acrylic acid copolymers, propylene acrylic acid copolymers, ethylene methacrylic acid copolymers, propylene methacrylic acid copolymers, and ethylene vinyl acetate copolymers. The resin preferably contains at least one of ethylene acrylic acid copolymers and ethylene methacrylic acid copolymers.

[0029] Carrier fluids and carrier liquids include hydrocarbons, silicone oils, vegetable oils, and the like. Hydrocarbons include aliphatic hydrocarbons, branched-chain aliphatic hydrocarbons, and aromatic hydrocarbons. The electrostatic ink composition may be substantially free of carrier liquid when printed onto a printing substrate, such as a primer layer. The carrier liquid may be removed, for example, by an electrophoretic process or evaporation during printing, thereby transferring substantially only solids to the printing substrate.

[0030] Charge directors serve to maintain a sufficient electrostatic charge on particles contained in the electrostatic ink composition, and include ionic compounds such as metal salts of fatty acids, metal salts of sulfosuccinates, metal salts of oxyphosphates, metal salts of alkylbenzene sulfonic acids, and metal salts of aromatic carboxylic or aromatic sulfonic acids, as well as zwitterionic and nonionic compounds such as polyoxyethylenated alkylamines, lecithin, polyvinylpyrrolidone, and organic acid esters of polyhydric alcohols.

[0031] Charge adjuvants have the effect of increasing or stabilizing the charge of particles contained in the electrostatic ink composition. Examples of charge adjuvants include barium petronate, calcium petronate, Co naphthenate, Ca naphthenate, Cu naphthenate, Mn naphthenate, Ni naphthenate, Zn naphthenate, Fe naphthenate, Ba stearate, Co stearate, Pb stearate, Zn stearate, Al stearate, Cu stearate, Fe stearate, and metal carboxylates.

[0032] The electrostatic ink composition may contain a crosslinked product formed by crosslinking with a component contained in the adhesive layer 30. This can sufficiently increase the strength of the electrostatic ink layer 50 itself, as well as the adhesive strength between the electrostatic ink layer 50 and the adhesive layer 30. It can also prevent gaps from forming at the interface between the electrostatic ink layer 50 and the adhesive layer 30. This improves the adhesive strength of the adhesive layer 30, and makes it possible to obtain a laminate 300 with sufficiently excellent tear resistance.

[0033] The thickness of the adhesive layer 30 may be 0.5 to 5 μm, 0.6 to 3 μm, or 0.8 to 2 μm, thereby achieving a good balance between adhesive strength and design.

[0034] The thickness of each layer constituting the laminate 300 can be measured by observing the cross section of the laminate 300 with a digital microscope.

[0035] The adhesive layer 30 may be composed of a solventless adhesive composition, a cured product thereof, or a mixture thereof. The adhesive composition may be a two-component curing type. The adhesive layer 30 contains two components: a polyisocyanate component and a polyol component. These components may at least partially react with each other to form a cured product. The cured product may also contain polyurethane. The adhesive layer 30 containing the above two components is in direct contact with the electrostatic ink layer 50. Being a solventless adhesive reduces the environmental impact. Furthermore, the polyol component and polyisocyanate component contained in the adhesive composition penetrate into the electrostatic ink layer, coagulating the electrostatic ink composition and sufficiently increasing adhesive strength. This makes it difficult for delamination to occur when torn, resulting in a laminate 300 with sufficiently excellent tearability.

[0036] The polyisocyanate component may contain a hexamethylene diisocyanate derivative (hereinafter, sometimes referred to as an "HDI derivative"). It is believed that hexamethylene diisocyanate derivatives tend to penetrate or blend easily into the electrostatic ink layer. This further increases the cohesive force of the electrostatic ink layer 50, further increasing the adhesive strength of the adhesive layer 30, resulting in a laminate 300 with even better tearability. The HDI derivative may be a bifunctional derivative of hexamethylene diisocyanate. The HDI derivative is an aliphatic diisocyanate and penetrates the electrostatic ink layer 50 more easily than aromatic diisocyanates. This improves the blending between the electrostatic ink layer 50 and the adhesive layer 30, improving the crosslinking effect between the adhesive layer 30 and the electrostatic ink layer 50.

[0037] The HDI derivative may be a trifunctional derivative of HDI (hexamethylene diisocyanate). Such a trifunctional derivative penetrates the electrostatic ink layer 50 and crosslinks with the components of the electrostatic ink layer 50. This increases the cohesive force of the electrostatic ink layer 50, further increasing the adhesive strength of the laminate 300. By including both a bifunctional derivative and a trifunctional derivative as the HDI derivative, the HDI derivative can be sufficiently penetrated into the electrostatic ink layer 50, further promoting the crosslinking reaction with the components of the electrostatic ink layer 50. This allows the adhesive layer 30 to maintain a sufficiently high adhesive strength and the laminate 300 to have even better tearability, even when the electrostatic ink layer 50 is thick.

[0038] In the adhesive layer 30 (adhesive composition), the content of the trifunctional derivative of HDI may be higher than the content of the bifunctional derivative of HDI. This allows a crosslinking reaction to proceed in the adhesive layer 30 and the electrostatic ink layer 50, improving the strength of the adhesive layer 30 and the electrostatic ink layer 50 and sufficiently increasing the adhesive strength between the adhesive layer 30 and the electrostatic ink layer 50. Therefore, a laminate 300 with even better tear resistance can be obtained. From this perspective, the mass ratio of the trifunctional derivative to the total of the bifunctional derivative and the trifunctional derivative may be 55% by mass or more, or even 60% by mass or more. On the other hand, from the perspective of maintaining the flexibility of the adhesive layer 30 and the electrostatic ink layer 50, the mass ratio of the trifunctional derivative to the total of the bifunctional derivative and the trifunctional derivative may be 85% by mass or less, 80% by mass or less, or 75% by mass or less. An example of the mass ratio of the trifunctional derivative to the total of the bifunctional derivative and the trifunctional derivative is 55 to 85% by mass.

[0039] Examples of HDI derivatives include HDI multimers (e.g., dimers, trimers, pentamers, heptamers, etc.), biuret-modified products (e.g., biuret-modified products produced by the reaction of HDI with water, tertiary alcohols, or amines), allophanate-modified products (e.g., allophanate-modified products produced by the reaction of HDI with alcohols), urea-modified products (e.g., urea-modified products produced by the reaction of HDI with diamines), oxadiazinetrione (e.g., oxadiazinetrione produced by the reaction of HDI with carbon dioxide), carbodiimide-modified products (e.g., carbodiimide-modified products produced by the decarboxylation condensation reaction of HDI), and polyol-modified products. HDI may also be an adduct of HDI with trimethylolpropane.

[0040] The content of the HDI derivative in the polyisocyanate component may be 15% by mass or more, 20% by mass or more, or 25% by mass or more. This allows the above-mentioned effects to be fully exhibited. The content of the HDI derivative in the polyisocyanate component may be 60% by mass or less, 50% by mass or less, or 40% by mass or less. An example of the content of the HDI derivative in the polyisocyanate component is 15 to 60% by mass.

[0041] The polyisocyanate component may further contain a polyisocyanate having two or more isocyanate groups in one molecule, which is different from the HDI derivative. This allows for flexibility in designing the laminate 300 according to the desired properties. Examples of such polyisocyanate monomers include aromatic diisocyanates, aromatic alicyclic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates.

[0042] Aromatic diisocyanates are highly reactive and easily cured, which allows for rapid production of the laminate 300. Examples of aromatic aliphatic diisocyanates include m- or p-phenylene diisocyanate or a mixture thereof, 2,4- or 2,6-tolylene diisocyanate or a mixture thereof (TDI), 4,4'-, 2,4'-, or 2,2'-diphenylmethane diisocyanate or a mixture thereof (MDI), 4,4'-toluidine diisocyanate (TODI), 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, and 1,5-naphthalene diisocyanate (NDI).

[0043] Examples of the araliphatic diisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof (XDI), 1,3- or 1,4-tetramethylxylylene diisocyanate or a mixture thereof (TMXDI), and ω,ω'-diisocyanato-1,4-diethylbenzene.

[0044] Examples of the aliphatic diisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 1,2-, 2,3- or 1,3-butylene diisocyanate, and 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate.

[0045] Examples of alicyclic diisocyanates include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate; IPDI), 4,4'-, 2,4'-, or 2,2'-dicyclohexylmethane diisocyanate or mixtures thereof (hydrogenated MDI), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane or mixtures thereof (hydrogenated XDI).

[0046] The polyisocyanate component may contain a derivative of the polyisocyanate monomer (polyisocyanate derivative). Examples of the polyisocyanate derivative include (for example, a dimer, trimer, pentamer, heptamer, etc.), allophanate-modified products (for example, an allophanate-modified product produced by reacting a polyisocyanate monomer with an alcohol), biuret-modified products (for example, a biuret-modified product produced by reacting a polyisocyanate monomer with water or an amine), urea-modified products (for example, a urea-modified product produced by reacting a polyisocyanate monomer with a diamine), oxadiazinetrione (for example, oxadiazinetrione produced by reacting a polyisocyanate monomer with carbon dioxide), and carbodiimide-modified products (for example, a carbodiimide-modified product produced by a decarboxylation condensation reaction of a polyisocyanate monomer).

[0047] The polyisocyanate component may include an isocyanate-terminated prepolymer. The isocyanate-terminated prepolymer is a urethane prepolymer having at least two isocyanate groups at the molecular end. The urethane prepolymer can be obtained by a urethane reaction between at least one member selected from the group consisting of a polyisocyanate monomer, a polyisocyanate derivative, and an isocyanate-terminated prepolymer and a polyol.

[0048] The polyol component may contain at least one selected from the group consisting of polyester polyols and polyether polyols. Among these, polyether polyols may be included from the viewpoints of reducing production costs and suppressing hydrolysis.

[0049] The polyether polyol may be a polyalkylene oxide. For example, it may be obtained by addition reaction of an alkylene oxide such as ethylene oxide and / or propylene oxide with a low molecular weight polyol as an initiator. Specific examples include polyethylene glycol, polypropylene glycol, and polyethylene polypropylene glycol (random or block copolymer). Other examples include polytetramethylene ether glycol obtained by ring-opening polymerization of tetrahydrofuran.

[0050] The polyester polyol can be obtained, for example, by a condensation reaction or transesterification reaction between a polyhydric alcohol and a polybasic acid, its alkyl ester, its acid anhydride, or its acid halide. Examples of the polyhydric alcohol include low-molecular-weight diols, low-molecular-weight triols, and low-molecular-weight polyols having four or more hydroxyl groups.

[0051] Examples of low molecular weight diols include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, neopentyl glycol, 1,6-hexanediol, 2,2-diethyl-1,3-propanediol, 3,3-dimethylolheptane, and 2-ethyl-2-butyl-1,3-propanediol.

[0052] Examples of low molecular weight triols include glycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, trimethylolethane, trimethylolpropane, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-(hydroxymethyl)pentane, and 2,2-bis(hydroxymethyl)-3-butanol.

[0053] Examples of low molecular weight polyols having four or more hydroxyl groups include tetramethylolmethane, pentaerythritol, dipentaerythritol, D-sorbitol, xylitol, D-mannitol, and D-mannite.

[0054] Examples of alkyl esters of polybasic acids include methyl esters and ethyl esters of polybasic acids. Examples of acid anhydrides include acid anhydrides derived from polybasic acids, such as oxalic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, 2-alkyl (C12 to C18) succinic anhydride, tetrahydrophthalic anhydride, and trimellitic anhydride.

[0055] The acid halides include those derived from the above-mentioned polybasic acids, such as oxalic acid dichloride, adipic acid dichloride, and sebacic acid dichloride.

[0056] In the adhesive layer 30 (adhesive composition), the mass ratio of the polyisocyanate component may be higher than the mass ratio of the polyol component. Specifically, the mass ratio of the polyisocyanate component to the polyol component may be 1 or more, 1.2 or more, or even 1.4 or more. In this way, by increasing the mass ratio of the polyisocyanate component to the polyol component, the curing reaction is promoted and the adhesion and curing process can be sufficiently shortened. From the same viewpoint, the mass ratio of the polyisocyanate component to the polyol component may be 4 or less, or even 3 or less. An example of the mass ratio of the polyisocyanate component to the polyol component is 1 to 4.

[0057] Examples of the sealant film 20 include a non-oriented polypropylene film (CPP film), a linear low-density polyethylene film (LLDPE film), and a low-density polyethylene film (LDPE film). The thickness of the sealant film 20 may be 10 to 150 μm, 20 to 100 μm, or 30 to 80 μm.

[0058] Fig. 2 is a cross-sectional view showing another example of a laminate. Fig. 2 shows a cross-section along the lamination direction (thickness direction) of the laminate. The laminate 310 has, in this order, a base film 10, a primer layer 40, an electrostatic ink layer 51, a first adhesive layer 30, an intermediate layer 21, a second adhesive layer 31, and a sealant film 20. The primer layer 40 and the electrostatic ink layer 51 are in contact with each other, and the electrostatic ink layer 51 and the adhesive layer 30 are in contact with each other.

[0059] A scar group 80 consisting of a plurality of scars 81 is formed on the laminate 310. As shown in FIG. 2, the scars 81 have through holes 82 that penetrate along the stacking direction of the laminate 310. The number and spacing of the scars 81 are not particularly limited. For example, the spacing between adjacent scars 81 may be 0.2 to 4 mm, 0.3 to 2 mm, or 0.4 to 1.5 mm. This spacing is the minimum value of the distance between adjacent scars 81. Note that a similar scar group 80 may also be formed on the laminate 300 of FIG. 1.

[0060] The electrostatic ink layer 51 is formed so as to cover the entire one surface of the primer layer 40. Therefore, the laminate 310 does not have a plain portion. However, in a modified example, the electrostatic ink layer 51 may be formed so as to cover a portion of one surface of the primer layer 40, similar to the electrostatic ink layer 50 of the laminate 300 in FIG. 1, and the laminate 310 may have a plain portion.

[0061] The intermediate layer 21 may have a flexible substrate. Examples of flexible substrates include films of biaxially oriented polypropylene (BOPP), polyethylene terephthalate (PET), oriented polyamide (OPA), and nylon (NY). The intermediate layer 21 may be, for example, a vapor-deposited film (e.g., a transparent vapor-deposited film) having a resin layer such as a PET film and a barrier layer (vapor-deposited layer) on the resin layer, or may be a metal layer or a barrier film. The vapor-deposited film is not limited to a transparent vapor-deposited film and may be a non-transparent metal vapor-deposited film. An example of the metal layer is aluminum foil.

[0062] The second adhesive layer 31 may have the same components and thickness as the adhesive layer 30 in Fig. 1. The material and thickness of the sealant film 20 may be as described for the sealant film 20 in the laminate 300 in Fig. 1. The other layers of the laminate 310 may be as described for the laminate 300 in Fig. 1.

[0063] The adhesive layer 30 (first adhesive layer 30) and / or the second adhesive layer 31 may contain a surface modifier that improves adhesion to the primer layer 40, the electrostatic ink layer 51, the intermediate layer 21, and the sealant film 20. When the intermediate layer 21 is a barrier layer made of metal or the like, the adhesive strength and sealing strength between the adhesive layer 30, 31 and the barrier layer can be further increased. When the barrier layer has a metal layer (aluminum layer) such as a metal foil (aluminum foil) or a metal film (aluminum film), the adhesive layer 30, 31 (adhesive composition) can further improve adhesion to the metal layer by containing a surface modifier. This further increases the adhesive strength of the adhesive layer, resulting in a laminate 300, 310 with even better tearability.

[0064] Examples of the surface modifier include those containing at least one selected from sulfamic acid, phosphoric acid, nitric acid, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, and ethyl hydroxyethyl cellulose.

[0065] The adhesive composition constituting the adhesive layer 30 may contain optional components such as the surface modifiers and additives described above in addition to the polyisocyanate component and polyol component. Examples of additives include antioxidants, UV absorbers, light stabilizers, fillers, silane coupling agents, epoxy resins, catalysts, coatability improvers, leveling agents, nucleating agents, lubricants, release agents, antifoaming agents, plasticizers, surfactants, pigments, dyes, organic fine particles, inorganic fine particles, antifungal agents, and flame retardants. The adhesive composition is solventless and does not contain solvents such as organic solvents. This reduces the environmental impact and significantly improves the working environment. Solventless adhesive compositions are heated during application.

[0066] The adhesive strength (lamination strength) of the adhesive layers 30 (first adhesive layer 30 and second adhesive layer 31) of the laminates 300, 310 may be 1.0 N / 15 mm width or more, 1.5 N / 15 mm width or more, or 2.0 N / 15 mm width or more. The adhesive strength (lamination strength) of the second adhesive layer 31 of the laminate 310 may be greater than the adhesive strength of the first adhesive layer 30. The adhesive strength of the laminates 300, 310 depends primarily on the cohesive strength of the electrostatic ink layers 50, 51 and the adhesive strength of the adhesive layers 30, 31. The stronger the cohesive strength of the electrostatic ink layers 50, 51 and the adhesive strength of the adhesive layers 30, 31, the more sufficiently the adhesive strength of the laminates 300, 310 can be increased. In such laminates 300, 310, the electrostatic ink layers 50, 51 and the adhesive layer 30 (first adhesive layer 30) are sufficiently bonded together, so that peeling between the layers of the laminates 300, 310 due to external force applied when tearing can be prevented. This results in excellent tearability. The adhesive strength (lamination strength) of the laminates 300, 310 may be 5.0 N / 15 mm width or less.

[0067] The adhesive strength in the present disclosure is a peel adhesive strength measured in accordance with the description of JIS K 6854-1: 1999. Specifically, it can be measured by the method described in the examples of the present disclosure.

[0068] The tearability of the laminates 300, 310 can be evaluated by the ease of tearing when tearing the laminates 300, 310. Specifically, the tearability can be evaluated by a sensory evaluation in which a prepared laminate is held with both hands and the laminate is torn by pulling one hand away from the other to determine whether the laminate can be torn smoothly.

[0069] The appearance of the laminate 300, 310 after tearing can be evaluated by visual inspection. The appearance after tearing may also be evaluated based on the appearance after opening a packaging bag obtained from the laminate 300, 310. The appearance after tearing can be evaluated based on whether or not the film stretches when the laminate 300, 310 or the packaging bag is torn.

[0070] The seal strength when the sealant films 20 of the laminates 300, 310 are bonded together may be 15.0 N / 15 mm width or more, 20.0 N / 15 mm width or more, or 25.0 N / 15 mm width or more. A seal strength within this range allows for packaging bags and packages with sufficiently high durability to be obtained. The seal strength can be measured in accordance with JIS K 7127:1999, "Plastics - Test methods for tensile properties - Part 3: Test conditions for films and sheets." The seal strength may be 100.0 N / 15 mm width or less. The range of the seal strength may be, for example, 15.0 to 100.0 N / 15 mm width, 20.0 to 100.0 N / 15 mm width, or 25.0 to 100.0 N / 15 mm width. The tear strength of the laminates 300, 310 may be within the above-mentioned numerical range.

[0071] The tear strength of the laminates 300, 310 may be 0.9 N or less, 0.8 N or less, or 0.7 N or less. When the tear strength is within this range, the force required to tear the laminates 300, 310 is reduced, allowing for smooth tearing. Therefore, a laminate with even better tearability can be obtained. Such a laminate is suitable for use in packaging bags and other packaging materials. The tensile strength of the laminate can be measured in accordance with JIS K 7128-1:1998, "Plastics - Testing methods for tear strength of films and sheets - Part 1: Trouser tear method." The tear strength of the laminates 300, 310 may be 0.1 N or more.

[0072] The laminate of the present disclosure is not limited to the structures shown in Figures 1 and 2. For example, it may have the following laminate structure. In each example, the leftmost layer is the base film 10, and the rightmost layer is the sealant film 20. In each example, the layers are arranged in order from left to right. The third adhesive layer described below may be the same adhesive layer as the adhesive layer 30 (first adhesive layer 30) and the second adhesive layer 31, or may be a different adhesive layer. The layer structure of the laminate is not limited to the following examples.

[0073] Example 1) PET film / primer layer / electrostatic ink layer / adhesive layer / LLDPE film (linear low-density polyethylene film) Example 2) Nylon film / primer layer / electrostatic ink layer / adhesive layer / LLDPE film Example 3) Transparent vapor-deposited PET film / primer layer / electrostatic ink layer / adhesive layer / CPP film (non-oriented polypropylene film) Example 4) Barrier nylon film / primer layer / electrostatic ink layer / adhesive layer / CPP film Example 5) Transparent vapor-deposited PET film / primer layer / electrostatic ink layer / first adhesive layer / PET film / second adhesive layer / CPP film Example 6) Transparent vapor-deposited PET film / primer layer / electrostatic ink layer / first adhesive layer / nylon film / second adhesive layer / CPP film Example 7) Transparent vapor-deposited PET film / primer layer / electrostatic ink layer / first adhesive layer / PET film / second adhesive layer / nylon film / third adhesive layer / CPP film Example 8) Transparent vapor-deposited PET film / primer layer / electrostatic ink layer / first adhesive layer / nylon film / second adhesive layer / PET film / third adhesive layer / CPP film Example 9) Transparent vapor-deposited PET film / primer layer / electrostatic ink layer / first adhesive layer / PET film / second adhesive layer / PET film / third adhesive layer / CPP film Example 10) OPP film / primer layer / electrostatic ink layer / adhesive layer / CPP film Example 11) OPP film / primer layer / electrostatic ink layer / adhesive layer / LLDPE film Example 12) Nylon film / primer layer / electrostatic ink layer / adhesive layer / CPP film Example 13) PET film / primer layer / electrostatic ink layer / adhesive layer / CPP film Example 14) PET film / primer layer / electrostatic ink layer / first adhesive layer / nylon film / second adhesive layer / LLDPE film Example 15) PET film / primer layer / electrostatic ink layer / first adhesive layer / aluminum foil / second adhesive layer / LDPE film Example 16) PET film / primer layer / electrostatic ink layer / first adhesive layer / aluminum foil / second adhesive layer / nylon film / third adhesive layer / LLDPE film

[0074] <Method of manufacturing laminate> An example of a method for manufacturing a laminate is described below. In this example, a laminate 300 shown in Fig. 1 is manufactured. The method includes the steps of first forming a primer layer 40 on one side of a substrate film 10, printing an electrostatic ink composition on the primer layer 40 to form an electrostatic ink layer 50 and obtaining a printed surface 52, adhering the printed surface 52 to one side of the sealant film 20 using a solventless adhesive composition containing a polyisocyanate component and a polyol component, and curing or semi-curing the adhesive composition to form an adhesive layer 30.

[0075] The primer layer 40 may be formed on one side of the substrate film 10 by flexographic printing or gravure printing. The primer layer 40 can be formed by crosslinking a resin raw material with a crosslinking agent. Crosslinking may be achieved by irradiation with ultraviolet light, heat, ionizing radiation such as an electron beam, or non-ionizing radiation such as microwave radiation. The electrostatic ink composition can be printed by electrostatic printing using a digital printer. As a digital printer, for example, the Indigo 20000 label and packaging digital printer manufactured by HP can be used. In this manner, the electrostatic ink layer 50 is formed, and the printed surface 52 is obtained.

[0076] Bonding of the printed surface 52 and one side of the sealant film 20 with the adhesive composition may be performed as follows. For example, a roll coater combining multiple rolls is used to heat and melt the adhesive composition to about 40 to 90°C, and the adhesive composition is applied to the printed surface 52 of the substrate film 10 or one side of the sealant film 20. Thereafter, the adhesive composition on the printed surface 52 or the adhesive composition on the sealant film 20 is placed opposite the bonding surface of the other substrate, and the adhesive composition is bonded to the bonding surface of the other substrate using a nip roll. The raw roll thus obtained is then aged. Aging progresses the curing of the adhesive composition, forming the adhesive layer 30. The aging temperature may be 20 to 50°C, and the aging time may be 0.5 to 5 days.

[0077] Thereafter, a blade is pressed against the surface of the base film 10 or the surface of the sealant film 20 of the obtained laminate film to form through-holes 82 as shown in FIG. 2, and a group of scars 80 is provided. The through-holes 82 may be formed by spreading rather than by punching. This prevents the generation of chips and prevents foreign matter from being mixed into packaging bags, etc. In this way, a laminate 300 can be produced that has a group of scars and that includes, in this order, the base film 10, the primer layer 40, the electrostatic ink layer 50, the adhesive layer 30, and the sealant film 20.

[0078] When manufacturing the laminate 310, the sealant film 20 is replaced with an intermediate layer 21 in the above-described process, and an adhesive composition that has been heated to, for example, about 40 to 90°C and melted is further applied to the surface of the intermediate layer 21 opposite the adhesive layer 30. The application of the adhesive composition here may also be performed using a roll coater combining multiple rolls. The applied adhesive composition and the sealant film 20 are then bonded together using a nip roll so that they face each other. The raw roll thus obtained is then aged. The aging process causes the adhesive composition to harden or semi-harden through a urethanization reaction, forming a second adhesive layer 31 containing a hardened product. Aging to obtain the first adhesive layer 30 and the second adhesive layer 31 may also be performed simultaneously.

[0079] Thereafter, a blade is pressed against the surface of the base film 10 or the surface of the sealant film 20 of the resulting laminate film to form through-holes 82, leaving a group of scars 80 consisting of a plurality of scars 81. The through-holes 82 may be formed by spreading rather than by punching. This prevents the generation of chips and prevents foreign matter from being mixed into packaging bags, etc. In this manner, a laminate 310 can be manufactured that includes the group of scars 80, as well as the base film 10, primer layer 40, electrostatic ink layer 50, first adhesive layer 30, intermediate layer 21, second adhesive layer 31, and sealant film 20, in this order. The laminates according to each of the modifications can also be manufactured in the same manner as the laminates 300 and 310.

[0080] The laminates 300 and 310 thus manufactured have the configurations and properties as described above. The explanations regarding the laminates 300 and 310 and their modifications also apply to the above-mentioned example of the manufacturing method.

[0081] The laminates 300, 310 have a printed surface 52 printed by digital printing (electrostatic printing), allowing for ample design freedom. Furthermore, the use of a solvent-free adhesive composition allows for a sufficient reduction in environmental impact. Furthermore, despite having such an electrostatic ink layer, a solvent-free adhesive composition, and a group of scars, the laminates 300, 310 have sufficiently excellent tearability. Such laminates 300, 310 are suitable for use as packaging materials. The laminates 300, 310 may be used as packaging materials to produce packaging bags and packages. The laminates 300, 310 are not limited to use as packaging materials and may be used for other purposes.

[0082] <Packaging bags and packaging> FIG. 3 is a plan view showing an example of a packaging bag and a package formed using the above-described laminate. The packaging bag 100 is formed by bonding the sealant films 20 of a pair of laminates 300 (310) together. The surface 300A (310A) on the base film 10 side becomes the outer surface of the packaging bag 100. The packaging bag 100 has a sealed portion 101 formed by bonding the peripheral edges of a pair of film-like, approximately rectangular laminates 300 (310) together, and a storage portion 102 formed between the pair of laminates 300 (310) by the sealed portion 101. That is, the side edges, bottom edge, and top edge of the packaging bag 100 are sealed by the sealed portion 101. The packaging bag 100 has a storage portion 102 in which a packaged item (e.g., food) is stored in a non-sealed portion (sheet portion) surrounded by the sealed portion 101. The sealed portion 101 at the bottom edge may be sealed after the packaged item is filled into the storage portion 102. The seal portion 101 is formed by heat sealing the sealant films 20 together.

[0083] It is not essential that the pair of packaging materials that make up the packaging bag 100 have the same layer structure, and for example, the pair of packaging materials may be composed of laminates having different layer structures.

[0084] To facilitate opening, the packaging bag 100 has a seal portion 101 at a side edge provided with a group of scars 80, each composed of a plurality of scars 81, each of which includes a through-hole penetrating in the depth direction in FIG. 3. The groups of scars 80 are provided in pairs on the left and right side edges of the packaging bag 100. A half-cut line 121 is provided to connect each pair of groups of scars 80. The half-cut line 121 can be formed using a laser. The group of scars 80 may be formed by pressing a blade against the sealed portion 101 after the sealed portion 101 is formed. The packaging bag 100 can be smoothly cut open along the half-cut line 121 from one group of scars 80 to the other group of scars 80.

[0085] The packaging bag 100 includes the laminates 300, 310, and therefore has sufficiently excellent tearability when opened despite having the scar group 80. Such a packaging bag 100 can be suitably used as a package.

[0086] The packaging body 200 comprises a packaging bag 100 and an item to be contained in the containing section 102 of the packaging bag 100. The item to be contained is not particularly limited and may be a solid, a liquid, or a mixture thereof. Examples of the item to be contained include food, beverages, medicines, electronic devices, etc. The packaging body 200 comprises the packaging bag 100 with the laminates 300, 310, and therefore has sufficiently excellent tearability when opened.

[0087] The procedure for manufacturing the packaging bag 100 and the packaging body 200 using the laminate 300 is described below. A pair of laminates 300 cut to a predetermined shape is prepared as packaging materials. The sealant films 20 provided on one side of each laminate 300 are placed opposite each other, and the sealant films 20 are bonded together. This forms sealed portions 101 at the bottom end (or top end) and side end, forming a U-shaped sealed portion 101 and an unsealed portion surrounded by the sealed portion 101. In this way, a packaging bag is obtained in which only the top end (or only the bottom end) is unsealed.

[0088] Next, the contents to be packaged are filled from the unsealed upper end (or lower end). Thereafter, the stacks 300 are bonded together at the upper end (or lower end), and a sealed portion 101 is also formed at the upper end (or lower end). Then, a blade is pressed against the sealed portion 101 at the side end, forming a group of scars 80 consisting of a plurality of scars 81 each including a through-hole. In this way, a package 200 comprising a packaging bag 100 and the contents contained therein can be manufactured.

[0089] FIG. 4 is a plan view showing another example of a packaging bag and packaging body formed using the above-described laminate. The packaging body 250 illustrated in FIG. 4 includes a packaging bag 150 and an item to be packaged, which is accommodated in the accommodation section 102 of the packaging bag 150. The packaging bag 150 is formed using the above-described laminate 300 (310). The packaging bag 150 is formed by bonding together the ends of the laminate 300 (310), which has been folded in half and stacked. The packaging bag 150 includes a U-shaped sealed section 101 formed by bonding together the ends of the laminate 300 (310), and an accommodation section 102 sealed by the sealed section 101. In other words, the packaging bag 150 is a so-called three-sided sealed bag, in which three sides, namely one side edge, the bottom edge, and the top edge, are sealed by the sealed section 101. The packaging bag 150 (packaging body 200) has a group of scars 80 in the non-sealed section 103 outside the sealed section 101 at the side edge.

[0090] When manufacturing a packaging bag 150 using the laminate 300 (310), the laminate 300 (310) having multiple band-shaped scar groups 80 extending along one direction is cut to a predetermined size along the one direction of the laminate 300 (310). At this time, the scars 81 may be exposed along the cut lines. In this manner, a laminate having scar groups 80 formed on both side edges is obtained. This laminate is folded in two along the one direction, and seal portions 101a extending in a direction perpendicular to the longitudinal direction are formed. Then, the contents to be packaged are filled while forming the seal portions 101 at the side edges, and seal portions 101b are formed in a direction perpendicular to the longitudinal direction so as to seal the filled contents. By repeating this process multiple times, a structure in which multiple packaging bags 150 (packaging bodies 250) are connected together along the one direction is obtained.

[0091] Thereafter, by cutting the sealed portion extending in a direction perpendicular to the longitudinal direction in half along that direction, a plurality of packaging bags 150 (packaging body 250) which are three-sided sealed bags as shown in Fig. 4 can be obtained. The packaging bag 150 can be smoothly cut open in a direction across the packaging bag 150, starting from the group of scars 80 provided in the non-sealed portion 103 at the side edge. The shapes of the packaging bag 150 and the packaging body 200 are not limited to those shown in Fig. 4.

[0092] The packaging bags 100, 150 and the packaging bodies 200, 250 are manufactured using the laminates 300, 310. This reduces the environmental impact, provides excellent tearability, and allows for a high degree of freedom in design, which can increase consumer purchasing interest.

[0093] Although several examples have been described above, this embodiment is not limited to the above examples. The shape of the packaging bag may be, for example, a four-sided bag, a zipper bag, a standing bag, a gusset bag, a two-sided bag, a three-sided bag, a folded bag, or the like.

[0094] The present disclosure includes the following embodiments. [1] A laminate comprising a substrate film, a primer layer, an adhesive layer, and a sealant film in this order, and a printed surface of an electrostatic ink composition adhered to the adhesive layer, the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; The adhesive strength of the adhesive layer is 1.0 N / 15 mm width or more, A laminate having a group of scars made up of a plurality of scars each including a through hole. [2] The laminate according to [1], wherein the polyisocyanate component includes a derivative of hexamethylene diisocyanate. [3] The laminate according to [1] or [2], which has a tear strength of 0.9 N or less. [4] The laminate according to any one of [1] to [3], wherein the ink coverage of the printed surface is 500% or less. [5] The laminate according to [2], wherein the polyisocyanate component further contains a polyisocyanate different from the derivative of hexamethylene diisocyanate. [6] The laminate according to [2] or [5], wherein the derivative of hexamethylene diisocyanate includes a bifunctional derivative of hexamethylene diisocyanate and a trifunctional derivative of hexamethylene diisocyanate. [7] The laminate according to [6], wherein the content of the trifunctional derivative is higher than the content of the bifunctional derivative. [8] The laminate according to any one of [1] to [7], wherein the mass ratio of the polyisocyanate component to the polyol component is 1 or more. [9] The laminate according to any one of [1] to [8], wherein the polyol component contains a polyether polyol.

[10] The laminate according to any one of [1] to [9], wherein the adhesive composition contains a surface modifier.

[11] A step of forming a primer layer on one side of a substrate film; printing an electrostatic ink composition on the primer layer to obtain a printed surface; a step of adhering the printed surface and a substrate including a sealant film using a solventless adhesive composition including a polyisocyanate component and a polyol component; a step of curing or semi-curing the adhesive composition to form an adhesive layer having an adhesive strength of 1.0 N / 15 mm width or more; and forming a group of scars consisting of a plurality of scars each including a through hole.

[12] The method for producing a laminate according to

[11] , wherein the polyisocyanate component contains a derivative of hexamethylene diisocyanate.

[13] The method for producing a laminate according to

[11] or

[12] , wherein the tear strength is 0.9 N or less.

[14] The method for producing a laminate according to any one of

[11] to

[13] , wherein the ink coverage of the printed surface is 500% or less.

[15] A packaging bag formed by heat-sealing the sealant films in the laminate according to any one of [1] to

[10] above.

[16] The packaging bag according to

[15] , wherein the group of scars is present in at least one selected from the group consisting of the sealed portion of the packaging bag and the non-sealed portion outside the sealed portion.

[17] A package comprising the packaging bag described in

[15] or

[16] above and an item to be contained in the container of the packaging bag. [Example]

[0095] The present disclosure will be described in more detail with reference to examples, comparative examples, and reference examples, but the present disclosure is not limited to the following examples.

[0096] <Evaluation of Laminates Using Adhesive Composition a> [Laminate fabrication] A commercially available biaxially oriented polypropylene film (OPP film, thickness: 30 μm) was prepared as a substrate film. An aqueous primer resin (a resin containing polyethyleneimine, manufactured by Michelman, product name: DP050) was applied to one side of this OPP film to form a primer layer. At this time, the amount of aqueous polyethyleneimine applied was 0.10 to 0.18 g / m 2 The water-based primer resin was applied to the OPP film so that the

[0097] An electrostatic ink layer was formed by applying an electrostatic ink composition to the surface of the primer layer using a digital printer (HP Indigo 20000 label and packaging digital printer). Four types of ink compositions were prepared: yellow (Y), magenta (M), cyan (C), and white (W), and an electrostatic ink layer was formed so that the ink coverage rate for W was 100%. The electrostatic ink composition used was an electrostatic ink composition (HP Indigo Electroink) containing a thermoplastic resin containing a copolymer of ethylene acrylic acid and ethylene methacrylic acid.

[0098] As polyisocyanate components, a derivative of diphenylmethane isocyanate (MDI) (MDI derivative, manufactured by Mitsui Chemicals, Inc.), a derivative of hexamethylene diisocyanate (HDI derivative I, manufactured by Mitsui Chemicals, Inc.), and a derivative of hexamethylene diisocyanate (HDI derivative II, manufactured by Mitsui Chemicals, Inc.) were prepared. HDI derivative I contained a bifunctional derivative of hexamethylene diisocyanate. HDI derivative II contained a trifunctional derivative of hexamethylene diisocyanate. The MDI derivative, HDI derivative I, and HDI derivative II were blended in a mass ratio of MDI derivative:HDI derivative I:HDI derivative II = 100:14:28 to prepare a polyisocyanate component.

[0099] A polyether polyol (manufactured by Mitsui Chemicals, Inc., product name: XRN-21B) was prepared as the polyol component. The polyol component and the polyisocyanate component were blended so that the mass ratio of the polyol component to the polyisocyanate component was 142 / 65 (≒2.18), and a surface modifier was further added to prepare adhesive composition a. This adhesive composition a was heated to approximately 40°C and applied to one side of an electrostatic ink layer formed on a substrate film using a roll coater to form a coating film with a predetermined thickness. The amount of adhesive composition a applied was approximately 2.0 g / m 2 This coating film and a commercially available unstretched polypropylene film (CPP film, thickness: 30 μm) serving as a sealant film were overlapped so as to face each other, and the electrostatic ink layer (or primer layer) on the base film and the CPP film were bonded together via the coating film (adhesive composition a) using a nip roll.

[0100] The adhesive composition a constituting the coating film was then cured or semi-cured by aging at 45°C for 2 days. In this way, a laminate having an OPP film, a primer layer, an electrostatic ink layer, an adhesive layer, and a CPP film in this order was obtained. This was designated the laminate of Example 1.

[0101] (Reference Example 1, Example 2, Comparative Example 1) A laminate was produced in the same manner as in Example 1, except that the ink coverage was set as shown in Table 1. A laminate having no electrostatic ink composition applied and no electrostatic ink layer and an ink coverage of 0% was used as Reference Example 1.

[0102] [Adhesion strength measurement] The adhesive strength of the prepared laminate was measured in accordance with JIS K 6854-1:1999. Specifically, the prepared laminate was cut into a 15 mm width to obtain a measurement sample. After peeling the edge of the measurement sample between the OPP film and the CPP film, the peel adhesive strength of the laminate was measured using a tensile tester at an angle of 90°, a pulling rate of 300 mm / min, and room temperature. This peel adhesive strength was defined as the adhesive strength. The measurement results are shown in Table 1.

[0103] [Tearability rating 1] The tearability of each laminate was evaluated by a sensory evaluation in which the laminate was actually torn. The sensory evaluation was carried out according to the following procedure. A sample of each laminate was held with both hands and torn by pulling one hand away from the other. When torn in this way, it was judged whether the laminate was torn smoothly or not. The samples used in this sensory evaluation did not have any scars. The results of the sensory evaluation were judged according to the following criteria based on the ease of tearing the sample. The results are shown in the "Tearability Evaluation 1" column in Table 1. A: There was little resistance when tearing the sample, and it could be torn smoothly by hand. B: There was a large resistance when tearing the sample, and it was not possible to tear it smoothly by hand.

[0104] [Seal strength measurement] The sealant films (CPP films) of each laminate were placed face-to-face and heat-sealed to form a heat-sealed section. The heat-sealing conditions were 160°C, 0.2 MPa, and 0.5 seconds. This welded the CPP films to prepare a 15 mm wide measurement sample. The seal strength of the sealed section of the prepared measurement sample was measured in accordance with JIS K 7127:1999. The peel strength between the heat seals was measured using a tensile tester under the following conditions: a peel angle of 90°, a tensile speed of 300 mm / min, and room temperature (20°C). This peel strength was defined as the seal strength. The measurement sample used did not have any scars. The measurement results are shown in the "Seal Strength" column of Table 1.

[0105] [Tear strength measurement] The tear strength of each laminate was measured according to JIS K 7128-1:1999. The measurement was carried out by pulling the laminate vertically using a tensile tester at a test speed of 200 mm / min at room temperature (20°C) and measuring the force required to completely tear the laminate in the MD direction. The measurement results are shown in Table 1.

[0106] [Tearability rating 2] The sealant layers of each laminate were placed facing each other and heat-sealed to obtain a packaging bag as shown in Figure 4. As shown in Figure 4, this packaging bag had a group of scars consisting of multiple scars, each with a through-hole, in the unsealed area outside the sealed area at the side edge. Each packaging bag was torn starting from the group of scars, and the tearability was evaluated according to the following criteria. The results are shown in the "Tearability Evaluation 2" column in Table 1.

[0107] A: There was little resistance when tearing the packaging bag, and it could be torn smoothly by hand. B: There was a lot of resistance when tearing the packaging bag, and it was not possible to tear it smoothly by hand. C: I couldn't tear it apart with my hands.

[0108] [Evaluation of appearance after tearing] The appearance of the packaging bag after tearing in the above-mentioned "Evaluation of tearability 2" was visually inspected and evaluated according to the following criteria. The results are shown in the "Appearance after tearing" column in Table 1. A: Almost no elongation of the CPP film was observed. B: A small amount of elongation of the CPP film was observed. C: The elongation of the CPP film was significant.

[0109] <Evaluation of Laminate Using Adhesive Composition b> (Comparative Examples 2 to 5, Reference Example 2) An organic solvent-based adhesive composition b with a solids concentration of 33% by mass was prepared by blending an aliphatic polyester polyol (manufactured by Mitsui Chemicals, Inc., product name: Takelac A626) as the base agent, a polyisocyanate (manufactured by Mitsui Chemicals, Inc., product name: Takenate A65) as the curing agent, and ethyl acetate as the solvent. The base agent and curing agent were blended in a mass ratio of base agent:curing agent = 16:1.

[0110] A primer layer was formed on a substrate film (OPP film) using the same procedure as in Example 1. Then, an electrostatic ink composition was applied to a portion of the surface of the primer layer using a digital printer (HP Indigo 20000 label and packaging digital printer) to form an electrostatic ink layer. The ink coverage of the electrostatic ink layer was as shown in Table 1. In Reference Example 2, as in Reference Example 1, the electrostatic ink composition was not applied.

[0111] The adhesive composition b was applied to the prepared electrostatic ink layer using a dry laminating device, and then hot air drying was performed to form a coating film consisting only of nonvolatile components. The coating amount of the nonvolatile coating film was approximately 2.0 g / m 2 This coating film and a commercially available unstretched polypropylene film (CPP film, thickness: 30 μm) serving as a sealant film were overlapped so as to face each other, and the electrostatic ink layer (or primer layer) on the base film and the sealant film were bonded together via the coating film (adhesive composition b) using a nip roll.

[0112] Thereafter, aging was carried out at 40°C for 2 days to cure or semi-cure the adhesive composition b that constitutes the coating film, thereby forming an adhesive layer. By this dry lamination method, laminates of Comparative Examples 2 to 5 were obtained, each having an OPP film, a primer layer, an electrostatic ink layer, an adhesive layer, and a CPP film in this order. Note that the laminate of Reference Example 2 had an OPP film, a primer layer, an adhesive layer, and a CPP film in this order.

[0113] The adhesive strength of the adhesive layer was measured by peeling the edges of the measurement samples of Comparative Examples 2 to 5 and Reference Example 2 between the OPP film and the CPP film using the same procedure as in Example 1. Furthermore, the seal strength and tear strength were measured, and evaluations of tearability 1 and 2, and appearance after tearing were also performed using the same procedure as in Example 1. The results are shown in Table 1.

[0114] <Evaluation of Laminates Using Adhesive Composition c> (Examples 3 to 6, Reference Example 3) As polyisocyanate components, a derivative of diphenylmethane isocyanate (MDI) (MDI derivative, manufactured by Mitsui Chemicals, Inc.), a derivative of hexamethylene diisocyanate (HDI derivative I, manufactured by Mitsui Chemicals, Inc.), and a derivative of hexamethylene diisocyanate (HDI derivative II, manufactured by Mitsui Chemicals, Inc.) were prepared. HDI derivative I contained a bifunctional derivative of hexamethylene diisocyanate. HDI derivative II contained a trifunctional derivative of hexamethylene diisocyanate. The MDI derivative, HDI derivative I, and HDI derivative II were blended in a mass ratio of MDI derivative:HDI derivative I:HDI derivative II = 100:14:28 to prepare a polyisocyanate component.

[0115] A polyether polyol (manufactured by Mitsui Chemicals, Inc., product name: XRN-21B) was prepared as the polyol component. The polyol component and the polyisocyanate component were blended so that the mass ratio of the polyol component to the polyisocyanate component was 142 / 65 (≒2.18), and a surface modifier was further added to prepare adhesive composition c.

[0116] A laminate was produced in the same manner as in Example 1, except that a solventless adhesive composition c was used instead of the adhesive composition a used in Example 1. Measurements of adhesive strength, seal strength, and tear strength, as well as evaluations 1 and 2 of tearability and appearance after tearing were carried out in the same manner as in Example 1. The results are shown in Table 1. In Reference Example 3, as in Reference Examples 1 and 2, no electrostatic ink layer was formed.

[0117] <Evaluation of Laminates Using Adhesive Composition d> (Examples 7 to 10, Reference Example 4) Solventless adhesive composition d was prepared using the same procedure as in Example 3, except that no surface modifier was added. Laminates of Examples 7 to 10 having an OPP film, a primer layer, an electrostatic ink layer, an adhesive layer, and a CPP film in this order were obtained using the same procedure as in Example 3, except that adhesive composition d was used instead of adhesive composition c. In Reference Example 4, no electrostatic ink layer was formed, as in Reference Examples 1 to 3. Measurements of adhesive strength, seal strength, and tear strength were performed using the same procedures as in Example 3, as well as evaluations of tearability 1 and 2 and appearance after tearing. The results are shown in Table 1.

[0118] [Table 1]

[0119] Each value in Table 1 indicates adhesive strength, sealing strength, or tear strength. The symbols "A," "B," and "C" indicate the results of the appearance evaluation after tearing and tearability evaluations 1 and 2. Columns where no measurement was performed are marked with a "-." The column below each value indicates the location of peeling when each strength was measured. In Table 1, "OPP / ad" indicates peeling at the interface between the OPP film and the adhesive layer. "OPP / ink" indicates peeling at the interface between the OPP film and the electrostatic ink layer. "Ink surface" indicates that the surface layer of the electrostatic ink layer migrated to the base film. "OPP cut" indicates that the OPP film was cut. "OPP surface" indicates that the surface layer of the OPP film migrated to the adhesive layer. "Ink surface" indicates that the electrostatic ink layer migrated to the adhesive layer. "Ink cohesion" indicates that the electrostatic ink layer itself broke. "Triangular peel" indicates that peeling occurred within the laminate, not between the sealant layers. "Ink / ad" indicates that the interface between the electrostatic ink layer and the adhesive layer has peeled off. "OPP / ink," "OPP / ad," and "ink / ad" correspond to interlayer peeling.

[0120] FIG. 5(A) is a photograph showing the packaging bag of Example 1 used to evaluate the appearance after tearing. FIG. 5(B) is a photograph showing the packaging bag of Example 2 used to evaluate the appearance after tearing. FIG. 5(C) is a photograph showing the packaging bag of Comparative Example 1 used to evaluate the appearance after tearing. As shown in FIGS. 5(A) and 5(B), almost no stretching of the CPP film was observed in the packaging bags of Examples 1 and 2. These packaging bags could be torn very smoothly starting from the group of scars. On the other hand, as shown in FIG. 5(C), stretching of the CPP film was observed in the packaging bag of Comparative Example 1. The packaging bag of Comparative Example 1 could not be torn smoothly starting from the group of scars.

[0121] Fig. 6(A) is a photograph showing the packaging bag of Comparative Example 2 used to evaluate the appearance after tearing. Fig. 6(B) is a photograph showing the packaging bag of Comparative Example 3 used to evaluate the appearance after tearing. Fig. 7(A) is a photograph showing the packaging bag of Comparative Example 4 used to evaluate the appearance after tearing. Fig. 7(B) is a photograph showing the packaging bag of Comparative Example 5 used to evaluate the appearance after tearing. From the photographs in Figs. 6(A) and (B) and 7(A) and (B), it was confirmed that the lower the adhesive strength, the more likely the CPP film to elongate. The packaging bags of Comparative Examples 2 to 5 use adhesive composition b containing an organic solvent, and therefore cannot reduce the environmental impact.

[0122] Laminates with an adhesive strength of 1.0 N / 15 mm width or more had good tearability. This is thought to be because in laminates with high adhesive strength, the adhesive layer is sufficiently bonded to the electrostatic ink layer, making delamination less likely to occur when torn. On the other hand, as the ink coverage increases, the thickness of the electrostatic ink layer increases, which reduces adhesive strength and makes delamination more likely to occur, resulting in poor tearability. When the ink coverage is 300% or more, adhesive strength tends to decrease. On the other hand, when the ink coverage is 200% or less, adhesive strength tends to increase.

[0123] These results indicate that laminates with an adhesive strength of 1.0 N / 15 mm width or more have excellent tearability. Therefore, it was confirmed that laminates with a scar group, an electrostatic ink layer, and a solvent-free adhesive layer and an adhesive strength of 1.0 N / 15 mm width or more have excellent tearability while reducing the environmental impact. [Industrial Applicability]

[0124] According to the present disclosure, it is possible to provide a laminate including an electrostatic ink layer that has excellent tearability while reducing the environmental impact, and a method for manufacturing the same. It is also possible to provide a packaging bag and a packaging body that include such a laminate. [Explanation of symbols]

[0125] 10...base film, 20...sealant film, 21...intermediate layer, 30...adhesive layer (first adhesive layer), 31...adhesive layer (second adhesive layer), 40...primer layer, 50, 51...electrostatic ink layer, 52...printed surface, 100, 150...packaging bag, 101, 101a, 101b...sealed portion, 102...storage portion, 103...non-sealed portion, 121...half-cut line, 200, 250...packaging body, 300, 310...laminated body.

Claims

1. A laminate comprising a substrate film, a primer layer, an adhesive layer, and a sealant film in this order, and a printed surface for an electrostatic ink composition adhered to the adhesive layer, the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; The adhesive strength of the adhesive layer is 1.0 N / 15 mm width or more, A laminate having a group of scars made up of a plurality of scars each including a through hole.

2. The laminate of claim 1 , wherein the polyisocyanate component comprises a derivative of hexamethylene diisocyanate.

3. The laminate according to claim 1 or 2, which has a tear strength of 0.9 N or less.

4. The laminate according to claim 1 or 2, wherein the ink coverage of the printed surface is 500% or less.

5. The laminate of claim 2 , wherein the polyisocyanate component further comprises a polyisocyanate different from the derivative of hexamethylene diisocyanate.

6. The laminate according to claim 2 , wherein the derivative of hexamethylene diisocyanate includes a bifunctional derivative of hexamethylene diisocyanate and a trifunctional derivative of hexamethylene diisocyanate.

7. The laminate according to claim 6 , wherein the content of the trifunctional derivative is higher than the content of the bifunctional derivative.

8. The laminate according to claim 1 or 2, wherein a mass ratio of the polyisocyanate component to the polyol component is 1 or more.

9. The laminate according to claim 1 or 2, wherein the polyol component comprises a polyether polyol.

10. The laminate of claim 1 or 2, wherein the adhesive composition comprises a surface modifier.

11. forming a primer layer on one side of a substrate film; printing an electrostatic ink composition on the primer layer to obtain a printed surface; a step of adhering the printed surface and a substrate including a sealant film using a solventless adhesive composition including a polyisocyanate component and a polyol component; a step of curing or semi-curing the adhesive composition to form an adhesive layer having an adhesive strength of 1.0 N / 15 mm width or more; and forming a group of scars consisting of a plurality of scars each including a through hole.

12. The method for producing a laminate according to claim 11 , wherein the polyisocyanate component comprises a derivative of hexamethylene diisocyanate.

13. The method for producing a laminate according to claim 11 or 12, wherein the tear strength is 0.9 N or less.

14. The method for producing a laminate according to claim 11 or 12, wherein the ink coverage of the printed surface is 500% or less.

15. A packaging bag formed by heat-sealing the sealant films in the laminate according to claim 1 or 2.

16. The packaging bag according to claim 15, wherein the group of scars is present in at least one selected from the group consisting of a sealed portion of the packaging bag and an unsealed portion outside the sealed portion.

17. A package comprising the packaging bag according to claim 15 and an item accommodated in the accommodating portion of the packaging bag.

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