JP7369342B2 - Containers and heating packaging bags - Google Patents

Description

The present disclosure relates to containers and heating packaging bags. The container according to the present disclosure particularly relates to a container that is formed of at least one laminate and has a bent portion.

2. Description of the Related Art Containers (for example, packaging bags) for sealing and preserving packaged items such as foods are known. As the container, a package using a thin film or sheet is often used. Such containers are printed with various information such as decoration, product, brand, and manufacturer. Digital printing using an electrostatic ink composition is known as a means for performing such printing. A digital printing machine is used for digital printing.

For example, in Patent Document 1, a primer resin is applied to a first flexible base material such as a PET film to obtain a coated surface, and a digital printing machine (manufactured by HP, Indigo 20000 digital printer for labels and packages) is applied to the coated surface. It has been proposed to carry out electrostatic printing using a printing press) and to apply a crosslinking composition. After performing the predetermined steps in this way, the first flexible base material coated with the predetermined component and the second flexible base material are laminated to form a laminate (packaging material for containers). ) has been proposed.

Japanese Patent Application Publication No. 2018-530478

Since digital printing using electrostatic ink compositions can be applied in small lots, digitally printed laminates are used as materials for various containers. However, the electrostatic ink layer composed of the printing part provided by a digital printing machine may not have sufficient adhesive strength with the primer layer or adhesive layer, and when an external force is applied, the electrostatic ink layer and the primer Delamination may occur between the layers or between the electrostatic ink layer and the adhesive layer. In particular, when the laminate is bent and its deformation is large, stress generated between the laminates is large, and peeling or the like may occur between the electrostatic ink layer and the primer layer or the adhesive layer. In such a situation, for example, the function as a container may be impaired, and the printed surface may be misaligned, making it difficult to read the printed information written on the printed surface. Although it is conceivable to not provide a printed surface on the bent portion, in order to meet diverse demands, it is necessary to print on the bent portion as well. Therefore, it would be useful to have a container that does not impair its function as a container and does not impair printed information even when it has a bent portion.

Furthermore, the electrostatic ink layer provided by a digital printing machine may not have sufficient adhesive strength with adjacent layers. Therefore, if a packaging material prepared by the above method is used in a packaging bag that is intended to be subjected to heat treatment such as boiling or retorting, there is a possibility that the packaging bag will break during heating.

One of the objects of the present disclosure is to provide an interface between an electrostatic ink layer and a primer layer, and an electrostatic ink layer even at bent portions that occur during the manufacturing process, even though the printing surface is printed by a digital printing machine. An object of the present invention is to provide a container in which peeling at the interface between the adhesive layer and the adhesive layer is suppressed.

Another object of the present disclosure is to provide a heating packaging bag that has an electrostatic ink layer produced by a digital printer and has sufficient resistance to heat treatment.

One form of the present disclosure is a container including a body portion having a bent portion, the body portion comprising at least one laminate, and the laminate comprising a base material, a primer layer, an adhesive layer, and a sealant layer in this order, the primer layer has a printed part made of an electrostatic ink composition on at least a part of the main surface on the side of the sealant layer, and the adhesive layer includes an adhesive containing an epoxy compound. A container containing at least one of an agent composition and a cured product thereof is provided.

Since the adhesive layer of the above container is composed of at least one of a specific adhesive composition and its cured product, it is possible to maintain a sufficient adhesion state even at bent parts, and the electrostatic ink layer and primer Peeling at the interface between the electrostatic ink layer and the adhesive layer and the interface between the electrostatic ink layer and the adhesive layer is suppressed. In addition, since the adhesion between each layer is maintained even at bent parts, the occurrence of misalignment of the printed parts is suppressed, and the printed information on the body parts, including the bent parts, is maintained in the initial state after printing. It is possible. In the process of using the container, even if new bends occur due to bending of the container, the adhesive state between each layer is maintained, so the function as a container (e.g., barrier properties, etc.) is maintained. It can be maintained over the period of use. Similarly, over the period of use, breakage of the container itself, deterioration of printed information, etc. can be suppressed.

The bent portion may have the printed portion. In the container according to the present disclosure, since the body portion is formed of the above-described specific laminate, changes in printed information are suppressed even when the printing portion is located at the bent portion.

The epoxy compound may include a difunctional alicyclic epoxy compound. Since the epoxy compound is difunctional, it can increase the number of crosslinking points with the electrostatic ink composition and more firmly bond the main surface (printed surface) of the primer layer and the adhesive layer.

The adhesive composition may further include a polyol, the polyol may include an aliphatic polyester polyol, and the epoxy compound may have epoxy groups at both ends. Such an adhesive layer can exhibit high lamination strength even in a high temperature environment.

The adhesive composition may further include a polyisocyanate, and the polyisocyanate may include a xylylene diisocyanate derivative. Such polyisocyanates and polyols have excellent reactivity. This improves the curability of the adhesive composition and further prevents peeling at the interface between the printed area (electrostatic ink layer) and the primer layer, and at the interface between the printed area (electrostatic ink layer) and the adhesive layer. Can be suppressed.

The device may further include a plug connected to the body portion.

The spout may include a cylindrical spout and a flange extending outward from a peripheral edge of a lower end of the spout.

The body portion may be composed of one piece of the laminate.

The body portion may be composed of two laminates serving as side sheets and one laminate serving as a bottom sheet.

Further, in order to achieve the above object, a heating packaging bag according to an embodiment of the present disclosure is composed of a laminate having a base material, a primer layer, an electrostatic ink layer, an adhesive layer, and a sealant layer in this order. In the packaging bag for heat treatment, the adhesive layer includes at least one of an adhesive composition containing an epoxy compound and a cured product thereof.

Printed areas formed by printing an electrostatic ink composition using a digital printer tend to have inferior heat resistance and strength compared to when other inks are used. For this reason, when trying to apply a laminate having a printed part (electrostatic ink layer) derived from a conventional electrostatic ink composition to a packaging bag for heat treatment, the adhesiveness near the printed surface is poor, so the packaging bag damage may occur. On the other hand, according to the above structure, the deformation of the laminate due to heating etc. is suppressed by curing the adhesive composition containing the epoxy compound. A packaging bag is obtained.

The primer layer may include polyethyleneimine resin. Since it has a primer layer containing a polyethyleneimine resin, water resistance is also improved, and in particular, sufficient resistance can be obtained even to heat treatment in an environment where a large amount of moisture exists, such as boil heat treatment or retort heat treatment.

The outer peripheral portion may include a sealing portion for bonding the sealant layers of the two laminates together, and the sealing portion may have an ink coverage of the electrostatic ink layer of 300% or less. Since the seal portion is an area where thermal adhesive processing such as heat sealing is performed, the possibility of damage is higher than other areas. On the other hand, by setting the ink coverage of the electrostatic ink layer within the above range, it is possible to ensure sufficient resistance to heat treatment for the sealing part, and to achieve stronger resistance to heat treatment. A heating packaging bag can be obtained.

The epoxy compound may include a difunctional alicyclic epoxy compound. Since such an epoxy compound is bifunctional, it can increase the number of crosslinking points with the electrostatic ink composition and more firmly bond the adhesive layer and the printed surface of the primer layer.

The adhesive composition may further include a polyol, the polyol may include an aliphatic polyester polyol, and the epoxy compound may have epoxy groups at both ends. Such an adhesive layer has high adhesive strength even in a high temperature environment. Therefore, even when the heating packaging bag is subjected to heat treatment, breakage of the electrostatic ink composition and damage to the packaging bag can be sufficiently suppressed.

The adhesive composition may further include a polyisocyanate, and the polyisocyanate may include a xylylene diisocyanate derivative. Such polyisocyanates and polyols have excellent reactivity. This improves the curability of the adhesive composition, thereby suppressing deformation of the heating packaging bag.

According to the present disclosure, although the printing surface is printed by a digital printing machine, the interface between the electrostatic ink layer and the primer layer and the adhesive between the electrostatic ink layer and the It is possible to provide a container in which peeling at the interface with the layer is suppressed.

According to the present disclosure, a heating packaging bag is provided that has an electrostatic ink layer produced by a digital printer and has sufficient resistance to heat treatment.

FIG. 1 is a perspective view showing an example of a container. FIG. 2 is a schematic cross-sectional view showing an example of a container equipped with a spout. FIG. 3 is a perspective view showing another example of the container. 4 is an end view taken along line IV-IV in FIG. 3. FIG. FIG. 5 is a cross-sectional view showing an example of a laminate. FIG. 6 is a sectional view showing another example of the laminate. FIG. 7 is a plan view showing an example of a packaging bag. FIG. 8 is a plan view showing another example of the packaging bag. FIG. 9 is a reference diagram showing the results of peeling suppression performance evaluation in Examples. FIG. 10 is a reference diagram showing the results of peeling suppression performance evaluation in Examples. FIG. 11 is a reference diagram showing the results of peeling suppression performance evaluation in Examples. FIG. 12 is a diagram illustrating the shape of a seal portion of a package according to an example and a comparative example.

Embodiments of the present disclosure will be described below, sometimes with reference to the drawings. However, the following embodiments are examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents. In the description, the same reference numerals will be used for the same elements or elements having the same function, and redundant description will be omitted in some cases. In addition, the positional relationships such as top, bottom, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios.

Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more. If there are multiple substances corresponding to each component in the composition, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified. .

[container]
One embodiment of the container is a container including a body portion having a bent portion, and the body portion is composed of at least one laminate, and the laminate includes a base material, a primer layer, an adhesive layer, and The sealant layer includes a sealant layer in this order, and has a printed portion made of an electrostatic ink composition on at least a portion of the main surface of the primer layer on the sealant layer side. The container may be, for example, a packaging bag, a tube container, a standing pouch, or the like. The packaging bag is not limited to one that is used at room temperature, but may be a packaging bag that is exposed to temperature changes such as for heating or freezing. The container may be, for example, a container that is intended to be further folded during use. In a tube container or the like, a new fold may be formed in the body when the body is pressed and deformed to remove the packaged item from the container. With the container of the present disclosure, the adhesive state between each layer is maintained even in such a case, so the function as a container (eg, barrier properties, etc.) can be maintained over the period of use.

FIG. 1 shows an example of a container. The container 100 is composed of a single sheet of a laminate 300. In the container 100, first, the sealant layers on two opposing sides of the substantially rectangular laminate 300 are bonded together with a predetermined width to form a seal portion 101 to form a cylinder, and then the cylinder has The container is obtained by bonding sealant layers with a predetermined width at one of the openings to form a seal portion 103. The container 100 has a bent portion 60 and seal portions 101 and 103 in a body portion 200. The bent portion 60 is formed by bending the seal portion 101 along the side surface of the body portion 200 in order to improve handling properties when used as a container.

The container 100 shown in FIG. 1 includes a storage part 102 formed by seal parts 101 and 103 and a non-seal part (sheet part) and in which an object to be packaged (for example, food or drink) is stored. In this specification, a package that houses and seals a packaged item is also referred to as a package. Note that the sealing portion 103 at the lower end may be sealed after the storage portion 102 is filled with the object to be packaged. The seal parts 101 and 103 are formed by heat-sealing the sealant layers of the laminate 300 to each other.

The container 100 may further include a spout that connects to the body section 200. FIG. 2 is a schematic cross-sectional view showing an example of a container equipped with a spout. In FIG. 2, a spout 70 is placed on the unsealed upper end of the container 100, and a sealant layer is heat-sealed to the spout 70 to connect the body 200 of the container 100 and the spout. An example of a container is shown. In this case, the container 100 includes a body portion 200 and a spout 70, and by pressing the body portion 200, the packaged item can be taken out from the spout. In this specification, such a container is also referred to as a tube container.

The spout 70 shown in FIG. 2 is shown as an example consisting of a cylindrical spout 72 and a flange 74 that extends outward from the periphery of the lower end of the spout 72. The spout may include a cylindrical spout and a flange that extends outward from the periphery of the lower end of the spout, and may be, for example, a spout. The position where the plug is provided is not particularly limited. When the spout is a spout, it may be a so-called center spout or a corner spout.

Another example of the container is shown in FIGS. 3 and 4. The container 110 is composed of two laminates 300 whose body portion 200 serves as side sheets and one laminate 306 which serves as a bottom sheet. The container 110 is constructed by pasting together the sealant layers of two laminates 300 serving as side sheets and one laminate 306 serving as a bottom sheet. The container 110 is constructed by pasting together a seal portion 122 obtained by pasting together two laminates 300 that will serve as side sheets, a laminate 306 that will serve as a bottom sheet, and two laminates 300 that will serve as side sheets. The seal portion 121 is obtained, thereby forming a bag-like shape. With such a configuration, the volume of the storage section 102 can be expanded. The laminate 306 serving as the bottom sheet has a bent portion 60 that occurs when the container 110 is manufactured. Note that the open non-sealed portion at the upper end of the container 110 may be sealed after the storage portion 112 is filled with the object to be packaged. The seal parts 122 and 121 are formed by heat-sealing the sealant layers of the laminate 300 to each other.

The three laminates constituting the container 110 do not necessarily have the same layer configuration, and may have different layer configurations, for example.

Containers 100, 110 may accommodate the object to be packaged in a non-sealed portion (sheet portion) surrounded by sealed portions 101, 121, 122, and in this specification, a sealed container is also particularly referred to as a package. . The container may be provided with opening means to facilitate opening. The unsealing means includes a pair of easy-to-open portions consisting of a non-sealed portion at the side end or a V-shaped notch formed in the sealed portion 122 at the side end, and a cut-out portion between the pair of easy-to-open portions. It may have a half-cut line serving as a trajectory. The half-cut line can be formed using a laser. The easy-opening processed portion is not limited to a V-shaped notch, but may be a U-shaped or I-shaped notch, or may have a group of scars.

The laminates constituting the containers 100 and 110 will be explained. FIG. 5 is a cross-sectional view schematically showing an example of a laminate. FIG. 5 shows a cross section of the laminate along the stacking direction (thickness direction). The laminate 302 includes a base material 10, a primer layer 40, an adhesive layer 30, and a sealant layer 20 in this order. The base material 10, the primer layer 40, the adhesive layer 30, and the sealant layer 20 may each have a film-like shape. The primer layer 40 may have a printed portion 52 made of an electrostatic ink composition on at least a portion of the main surface (printed surface) on the sealant layer 20 side. An electrostatic ink layer 50 composed of one or more printing portions 52 is provided on the printing surface. In other words, the electrostatic ink layer 50 constituted by the printed portion 52 may be provided on at least a portion of one of the pair of main surfaces of the primer layer 40 that is closer to the sealant layer 20 .

The thickness of the laminate 302 may be, for example, 15 to 200 μm or 18 to 120 μm.

Substrate 10 and sealant layer 20 may be flexible substrates. Examples of flexible substrates include biaxially oriented polypropylene (BOPP), polyethylene terephthalate (PET), oriented polyamide (OPA), unoriented polypropylene (CPP), linear low density polyethylene (LLDPE), and low density Examples include polyethylene (LDPE).

The base material 10 may be, for example, a composite film in which metal foil is laminated onto a flexible base material, or a vapor-deposited film in which a metal or the like is deposited on a flexible base material. Note that the metal may be, for example, an elemental metal such as aluminum or a metal oxide such as aluminum oxide. From the viewpoint of improving gas barrier properties, the base material 10 may be a vapor-deposited film (transparent vapor-deposited film) in which aluminum, aluminum oxide, or the like is vapor-deposited on a PET film. The thickness of the base material 10 may be, for example, 7 to 150 μm, 15 to 90 μm, or 20 to 80 μm.

Examples of the sealant layer 20 include a CPP film, an LLDPE film, and an OPP film. The thickness of the sealant layer 20 may be the same as or different from the thickness of the base material 10, and may be, for example, 7 to 150 μm, 15 to 90 μm, or 20 to 80 μm.

Primer layer 40 may contain resin. Examples of the resin include polyvinyl alcohol resin, cellulose resin, polyester, polyamine, polyethyleneimine resin, polyamide resin, polyurethane, polyacrylic polymer hydroxyl-containing resin, carboxyl group-containing resin, and amine polymer. By providing the primer layer 40 on the substrate to be printed, the electrostatic ink composition can be printed smoothly using a digital printing machine. The coating amount of the resin constituting the primer layer 40 may be, for example, 0.01 to 1.5 g/m ² or 0.05 to 1.0 g/m ² .

The laminate 302 includes a printed portion 52 on the main surface (printed surface) of the primer layer 40 on the opposite side from the base material 10 . An electrostatic ink layer 50 composed of a plurality of printing parts 52 is provided on the printing surface. The electrostatic ink layer 50 is made of an electrostatic ink composition, and is provided by electrostatic printing using a digital printing machine. In FIG. 5, the plurality of printed parts 52 may have the same composition, or may have different colors due to having different compositions. The printed portions 52 may be provided so as to be scattered on the primer layer 40, or may be provided so as to cover the entire one side of the primer layer 40.

The printed portion 52 in the electrostatic ink layer 50 is composed of circular halftone dots of an electrostatic ink composition. In other words, even if it appears uniform with a single color, there is a plain area between the halftone dots. In the electrostatic ink layer 50, when printing a predetermined area to be printed in a single color, circular halftone dots are generally arranged spaced apart from each other, and when printing in two or more colors, the circular halftone dots are printed in the first color. The circular halftone dots of the electrostatic ink compositions of the second and subsequent colors are arranged between the halftone dots or partially overlapping the halftone dots printed in the first color. By changing the size of the halftone dots, the shade of color on the printing surface can be adjusted, and by arranging halftone dots of different colors, the tone on the printing surface can also be adjusted.

The ink coverage of each printed portion 52 constituting the electrostatic ink layer 50 is 500% or less, but may be, for example, 450% or less, or 400% or less. By setting the ink coverage of the printing part 52 within the above range, the laminated body has excellent lamination strength, and printing using a plurality of inks is possible, making it possible to correspond to various types of printing. The lower limit of the ink coverage of the printing section 52 is not particularly limited, but may be, for example, 20% or more, 50% or more, 80% or more, or 100% or more. The ink coverage of the printing section 52 may be adjusted within the above-mentioned range, and may be, for example, 20-500%, 50-400%, 100-400%, or 100-300%.

In this specification, ink coverage expresses the ratio of halftone dot area per unit area, and is the ink coverage when a predetermined area to be printed is uniformly printed in a single color. is 100%, and the ink coverage of the non-printed area is 0%. When printing is performed using inks of a plurality of colors, the ink coverage is calculated for each color of ink, and the sum is taken as the ink coverage of the target printing section and electrostatic ink layer. The ink coverage rate is set by the digital printing machine, and can be adjusted by specifying a desired value in the ink coverage setting. As the digital printing machine, for example, "Indigo 20000 Digital Printing Machine for Labels and Packages" (product name) manufactured by HP, etc. can be used. Note that the ink coverage of the electrostatic ink layer in the target laminate can also be confirmed by observing the printed surface of the container or laminate with an optical microscope.

Note that since the printed portion 52 is composed of circular halftone dots of the electrostatic ink composition, even if the ink coverage is 100%, the surface of the electrostatic ink layer 50 on the sealant layer 20 side is When observed with an optical microscope or the like, the main surface of the primer layer 40 can be confirmed. That is, even if the ink coverage is 100%, the primer layer 40 and adhesive layer 30 can be directly bonded to each other. On the other hand, as the ink coverage increases, the proportion of the primer layer 40 on the adhesive surface (interface) between the printed portion 52 and the adhesive layer 30 tends to decrease. When conventional adhesives are used, as the ink coverage increases, the adhesive force at the interface between the electrostatic ink layer and the primer layer or the interface between the electrostatic ink layer and the adhesive layer decreases, resulting in a laminate as a laminate. There may be cases where the strength is not as strong as expected. On the other hand, in the laminate according to the present disclosure, by using the adhesive composition described below, sufficient laminate strength can be exhibited even when the ink coverage is large. In the laminate according to the present disclosure, by using the adhesive composition described below, expansion of the laminate 300, etc., particularly during heat treatment, can be prevented.

The amount of ink applied on the main surface (printing surface) of the primer layer 40 on the side of the sealant layer 20 is, for example, 0.5 g/m ² or more, 1.0 g/m ² or more, 2.0 g/m 2 or more, or 3.0 g/m ² or more. It may be 0 g/m ² or more. By setting the ink application amount within the above range, it is possible to obtain a variety of printing expressions composed of multiple colors. The amount of ink applied on the main surface of the primer layer 40 on the sealant layer 20 side may be, for example, 8.0 g/m ² or less, or 6.0 g/m ² or less. By setting the amount of ink applied within the above range, a decrease in adhesive force at the interface between the electrostatic ink layer 50 and the primer layer 40 or the interface between the electrostatic ink layer 50 and the adhesive layer 30 is more fully suppressed. can. In this specification, the amount of ink applied means the total amount (solid content) of the ink composition used for printing, and in the case of printing in multiple colors, it means the total value.

FIG. 6 is a sectional view showing another example of the laminate. The laminate 304 in FIG. 6 is different from the laminate 302 in FIG. It is different from That is, in the laminate 304, the coverage ratio of the main surface of the primer layer 40 by the electrostatic ink layer 51 is 100 area %. By using the adhesive composition described below, even in a structure such as the laminate 304 where it is difficult to secure a sufficient direct bonding area between the primer layer 40 and the adhesive layer 30, sufficient bonding strength can be achieved. However, interlayer peeling and the like in the laminate 304 are suppressed.

In the laminates 302 and 304, the electrostatic ink compositions constituting the electrostatic ink layers 50 and 51 are ink compositions used for liquid electrophotographic printing, that is, electrostatic printing, and are suitable for substrates such as paper and plastic, or printed on the primer layer. Electrostatic ink compositions may include colorants such as pigments and dyes, and resins. The electrostatic ink composition may also further include a carrier fluid or liquid. Electrostatic ink compositions may include, for example, charge directors, charge adjuvants, surfactants, viscosity modifiers, emulsifiers, and other additives.

Examples of the coloring agent include cyan pigment, magenta pigment, yellow pigment, and black pigment. From the viewpoint of facilitating digital printing, a resin having a relatively low melting point can be used as the resin. A relatively low melting point may be, for example, 100°C or lower. Examples of the resin include thermoplastic resins such as ethylene acrylic acid copolymer, propylene acrylic acid copolymer, ethylene methacrylic acid copolymer, propylene methacrylic acid copolymer, and ethylene vinyl acetate copolymer. Preferably, the resin includes at least one of an ethylene acrylic acid copolymer and an ethylene methacrylic acid copolymer.

Examples of carrier fluids and carrier liquids include hydrocarbons, silicone oils, vegetable oils, and the like. Examples of hydrocarbons include aliphatic hydrocarbons, branched-chain aliphatic hydrocarbons, and aromatic hydrocarbons. The electrostatic ink composition may be substantially free of carrier fluid and carrier liquid when printed on a substrate. The carrier fluid and carrier liquid may be removed, for example, by an electrophoretic process or by evaporation during printing. Substantially only the solid content is transferred onto the substrate or primer layer by the above removal operation.

The charge director functions to maintain sufficient electrostatic charge on the particles included in the electrostatic ink composition. Examples of the charge director include metal salts of fatty acids, metal salts of sulfosuccinate, metal salts of oxyphosphate, metal salts of alkylbenzenesulfonic acids, metal salts of aromatic carboxylic acids, and metal salts of aromatic sulfonic acids. and diionic and nonionic compounds such as polyoxyethylenated alkylamines, lecithin, polyvinylpyrrolidone, and organic acid esters of polyhydric alcohols.

The charge adjuvant has 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, naphthenate Co salt, naphthenate Ca salt, naphthenate Cu salt, naphthenate Mn salt, naphthenate Ni salt, naphthenate Zn salt, naphthenate Fe salt, Examples include stearic acid Ba salt, stearic acid Co salt, stearic acid Pb salt, stearic acid Zn salt, stearic acid Al salt, stearic acid Cu salt, stearic acid Fe salt, and metal carboxylates.

The electrostatic ink layers 50 and 51 may include a crosslinked product crosslinked by a component contained in at least one of the adhesive layer 30 and the primer layer 40. By including the crosslinked material, the strength of the electrostatic ink layers 50 and 51 themselves, the adhesive strength between the printing surface of the primer layer 40 and the electrostatic ink layer 50, and the adhesive strength between the electrostatic ink layer 50 and the adhesive layer 30 are improved. Adhesive strength can be further improved.

The printed portion 52 of the electrostatic ink composition and the adhesive layer 30 are adhered to each other. That is, the printed portion 52 serves as an adhesive surface with the adhesive layer 30, and the electrostatic ink composition and the adhesive composition are in direct contact.

The adhesive composition contains an epoxy compound. When the epoxy compound reacts with the components constituting the electrostatic ink composition, the adhesive layer, and the primer layer and is cured, the adhesive layer and the printed surface of the primer layer can be firmly bonded. The epoxy compound itself may be cured to form a cured product. The adhesive composition may further contain at least one selected from the group consisting of polyol and polyisocyanate, may further contain polyol, may further contain polyisocyanate, and may further contain polyol and polyisocyanate. The adhesive composition may contain a polyol, a polyisocyanate, and an epoxy compound. At least a portion of these three components (polyol, polyisocyanate, and epoxy compound) may react with each other and be cured to form a cured product. That is, the adhesive composition may be composed of at least one of an adhesive composition containing a polyol, a polyisocyanate, and an epoxy compound, and a cured product thereof, and the adhesive layer 30 includes the adhesive composition, a cured product thereof, Or it may be composed of a mixture of these. Polyol and polyisocyanate act as a base agent and a curing agent, respectively, to react to produce polyurethane (polyurethane adhesive).

The epoxy compound may be a compound having one or more epoxy groups in one molecule. From the viewpoint of further increasing the adhesive strength of the adhesive layer 30 in a high-temperature environment, it may have epoxy groups at both ends. Examples of the epoxy compound include glycidyl ether type epoxy compounds, glycidyl amine type epoxy compounds, glycidyl ester type epoxy compounds, and alicyclic epoxy compounds (cycloaliphatic epoxy compounds).

The epoxy compound in the adhesive composition can penetrate layers adjacent to the adhesive layer, such as primer layers, electrostatic ink layers, sealant layers, and the like. By penetrating in this way, the adhesion between the respective layers after the epoxy compound is cured can be further improved. In this case, the primer layer, the electrostatic ink layer, and the sealant layer contain at least one of an epoxy compound and a cured product thereof (such as an epoxy resin). The molecular weight of the epoxy compound may be, for example, 500 or less, 450 or less, or 400 or less. When the molecular weight of the epoxy compound is within the above range, the epoxy compound can more fully penetrate into the electrostatic ink composition constituting the electrostatic ink layer. The lower limit of the molecular weight of the epoxy compound may be, for example, 98 or more.

Examples of the alicyclic epoxy compound include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate and bis(epoxycyclohexyl)adipate.

Examples of the monofunctional alicyclic epoxy compound having one epoxy group in one molecule include 3,4 epoxycyclohexylmethyl methacrylate and 1,2-epoxy-4-vinylcyclohexane. Examples of bifunctional epoxy compounds having two epoxy groups in one molecule include 3',4'-epoxycyclohexylmethyl-3,4 epoxycyclohexane carboxylate, and bis(3,4-epoxycyclohexylmethyl) adipate. , and 4-vinylcyclohexene dioxide. In addition, as an epoxy compound having one or more epoxy groups in one molecule, 1,2-epoxy-4-2,2-bis(hydroxymethyl)-1-butanol represented by the following general formula (I) (2-oxiranyl)cyclohexane adducts are mentioned.

In the above general formula (I), n may be an integer of 1 to 4.

The epoxy compound preferably includes a difunctional alicyclic epoxy compound. By being bifunctional, it is possible to increase the number of crosslinking points with the electrostatic ink composition and primer resin, promote the curing reaction of the adhesive, and make it easier to cure. Furthermore, when the adhesive composition further contains a polyisocyanate, the epoxy compound is alicyclic, so that reaction with the polyisocyanate can be suppressed due to steric hindrance. Therefore, it can be stably cured, and the adhesion between the printed part 52 and the adhesive layer 30 can be made sufficiently excellent.

The polyol has two or more hydroxyl groups in one molecule, and may have a number average molecular weight of 400 or more, for example. The number average molecular weight of the polyol may be, for example, 10,000 or less.

The polyol may contain, for example, at least one selected from the group consisting of polyester polyols and polyether polyols. Among these, from the viewpoint of sufficiently increasing the adhesive strength of the adhesive layer 30 in a high-temperature environment, the polyol may include a polyester polyol or an aliphatic polyester polyol.

Polyester polyols are obtained, for example, by a condensation reaction or transesterification reaction between a polyhydric alcohol and a polybasic acid, an alkyl ester of a polybasic acid, an acid anhydride of a polybasic acid, or an acid halide of a polybasic acid. .

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.

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, and 3-methyl- 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, neopentyl glycol, 1,6-hexanediol, 2,2-diethyl-1,3-propanediol, 3,3-dimethylol Examples include heptane and 2-ethyl-2-butyl-1,3-propanediol.

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

Examples of the low molecular weight polyol having four or more hydroxyl groups include tetramethylolmethane, pentaerythritol, dipentaerythritol, D-sorbitol, xylitol, D-mannitol, and D-mannitol.

Examples of the alkyl ester of polybasic acid include methyl ester of polybasic acid, ethyl ester of polybasic acid, and the like. Examples of acid anhydrides of polybasic acids include acid anhydrides derived from polybasic acids. More specifically, the acid anhydrides of polybasic acids include oxalic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, 2-alkyl (carbon number 12 to 18) succinic anhydride, tetrahydrophthalic anhydride, and trimellitic anhydride.

Examples of the acid halide of a polybasic acid include acid halides derived from the alkyl esters of the above-mentioned polybasic acids or acid anhydrides of the polybasic acids. More specific examples of the acid halide of a polybasic acid include oxalic acid dichloride, adipic acid dichloride, and sebacic acid dichloride.

Examples of polyether polyols include polyalkylene oxide. The polyether polyol may be, for example, one obtained by addition reaction of alkylene oxide such as ethylene oxide and/or propylene oxide using a low molecular weight polyol as an initiator. More specific examples of the polyether polyol include polyethylene glycol, polypropylene glycol, and polyethylene polypropylene glycol (random or block copolymer). Examples of the polyether polyol include polytetramethylene ether glycol obtained by ring-opening polymerization of tetrahydrofuran and the like.

Polyisocyanate has two or more isocyanate groups in one molecule. Examples of the polyisocyanate include polyisocyanate monomers, polyisocyanate derivatives, and isocyanate group-terminated prepolymers. The adhesive composition may contain multiple types of polyisocyanates that are different from each other. The molar ratio (NCO/OH) of the isocyanate groups contained in the polyisocyanate to the hydroxyl groups of the polyol may be, for example, 0.5 to 10. Such an adhesive composition can form a cured product that has high adhesive strength and excellent flexibility.

Examples of the polyisocyanate monomer include aliphatic polyisocyanates, aromatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates.

Examples of aliphatic polyisocyanates include trimethylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate (tetramethylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate), 1 , 5-pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl capate, etc. Can be mentioned.

Examples of the aromatic aliphatic polyisocyanate include xylylene diisocyanate derivatives. Examples of xylylene diisocyanate derivatives include xylylene diisocyanate (1,3-xylylene diisocyanate or 1,4-xylylene diisocyanate) (XDI), tetramethylxylylene diisocyanate (1,3-tetramethylxylylene diisocyanate) or 1,4-tetramethylxylylene diisocyanate) (TMXDI), ω,ω'-diisocyanate-1,4-diethylbenzene, and polyol modification of xylylene diisocyanate obtained by reaction of xylylene diisocyanate and trimethylolpropane. Examples include the body.

The content of the xylylene diisocyanate derivative relative to the entire polyisocyanate is, for example, 10% by mass or more, 20% by mass or more, 30% by mass or more, or 40% by mass or more, from the viewpoint of improving reactivity with the main agent (e.g., polyol). It may be. By setting the content of the xylylene diisocyanate derivative to the entire polyisocyanate to be 30% by mass or more, the reactivity can be further increased.

Examples of the alicyclic polyisocyanate include 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, cyclohexane diisocyanate (1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate), 3-isocyanatomethyl-3 , 5,5-trimethylcyclohexyl isocyanate (isophorodiisocyanate) (IPDI), methylcyclohexane diisocyanate (methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate), and norbornane diisocyanate (NBDI). .

Examples of polyisocyanate derivatives include multimers of the above-mentioned polyisocyanate monomers, allophanate modified products, polyol modified products, polyol modified products produced by reaction of monomers with alcohols, biuret modified products, and urea modified products. , oxadiazinetrione modified products, carbodiimide modified products, uretdione modified products, and uretonimine modified products.

The isocyanate group-terminated prepolymer is a urethane prepolymer having at least two isocyanate groups at the molecular ends. The isocyanate group-terminated prepolymer can be obtained by subjecting at least one selected from the group consisting of polyisocyanate monomers, polyisocyanate derivatives, and isocyanate group-terminated prepolymers and a polyol to a urethane reaction. At this time, the molar ratio (NCO/OH) of the isocyanate groups contained in the polyisocyanate to the hydroxyl groups of the polyol is, for example, 0.5 or more, 0.6 or more, 0.8 or more, 1 or more, or 1.5 or more. It may be. The molar ratio (NCO/OH) may be 10 or less, 5 or less, 4 or less, or 3 or less. Examples of numerical ranges for the molar ratio (NCO/OH) include, for example, 0.5-10, 0.5-5, 0.8-4, and 0.6-3.

In the adhesive composition, the content of the epoxy compound relative to 100 parts by mass of polyol is, for example, 3 to 25 parts by mass, 6 to 25 parts by mass, or 8 to 25 parts by mass, from the viewpoint of achieving both high adhesive strength and excellent shear suppressing force. It may be 20 parts by mass. When the content of the epoxy compound becomes too large, the excellent shear restraining force tends to be impaired. That is, when the adhesive layer 30 is formed, the adhesive surface may shift or the adhesive composition may protrude. If the amount of the epoxy compound is too small, the adhesive strength under high-temperature hydrothermal treatment conditions tends to decrease.

In the adhesive composition, the content of polyisocyanate based on 100 parts by mass of polyol is, for example, 10 to 50 parts by mass, 15 to 35 parts by mass, from the viewpoint of sufficiently increasing seal strength and adhesive strength under high temperature hot water treatment conditions. parts, or 20 to 30 parts by weight.

The molar ratio of the epoxy groups contained in the epoxy compound to the isocyanate groups contained in the polyisocyanate may be, for example, from 0.5 to 10, from 1.5 to 9, or from 2.0 to 6.5. This makes it possible to maintain sufficiently high adhesive strength under high temperature hydrothermal treatment conditions.

The adhesive composition constituting the adhesive layer 30 may contain optional components such as additives in addition to the above-mentioned components. Examples of additives include antioxidants, ultraviolet absorbers, light stabilizers, fillers, silane coupling agents, epoxy resins, catalysts, coating improvers, leveling agents, nucleating agents, lubricants, mold release agents, Examples include antifoaming agents, plasticizers, surfactants, pigments, dyes, organic fine particles, inorganic fine particles, fungicides, and flame retardants. The adhesive composition may contain a solvent such as an organic solvent.

The adhesive composition adheres the sealant layer 20 to the printed portion 52 on which the electrostatic ink composition is printed. An arbitrary layer may be provided between the adhesive layer 30 and the sealant layer 20. The laminates 302 and 304 may further include a barrier layer or the like between the adhesive layer 30 and the sealant layer 20, for example. In this case, the adhesive composition adheres the printed portion 52 and any layer (for example, a barrier layer, etc.). When the adhesive composition contains a polyol and a polyisocyanate, the polyol and the polyisocyanate react to form a urethane bond and can more fully function as an adhesive. Since the formation of the urethane bond proceeds smoothly even in the presence of the epoxy compound, the printed portion 52 and the sealant layer 20 or any other layer can be bonded with sufficiently high adhesive strength.

The adhesive composition may have the function of forming urethane bonds and crosslinking the electrostatic ink compositions forming the electrostatic ink layers 50 and 51. Thereby, the adhesive strength between the printed surface and the sealant layer 20 or any other layer can be further improved.

When the coverage ratio of the main surface (printing surface) of the primer layer 40 by the electrostatic ink layer 50 becomes high, or when the ink coverage ratio in the printing part 52 (electrostatic ink layers 50 and 51) becomes high, generally the electrostatic ink Although the adhesive force between the layer 50 and the adhesive layer 30 tends to decrease, the adhesive composition described above can exhibit sufficient adhesive strength. In addition, when the coverage ratio of the main surface of the primer layer 40 by the electrostatic ink layer 50 or the ink coverage ratio in the printed portion 52 (electrostatic ink layers 50, 51) increases, the adhesive composition may be added accordingly. By increasing the content of the epoxy compound, the epoxy compound can be sufficiently permeated into the electrostatic ink layers 50 and 51 formed of the electrostatic ink composition, and a decrease in adhesive strength can be further suppressed. The permeated epoxy compound has the effect of increasing the strength of the electrostatic ink composition (electrostatic ink layers 50 and 51) by crosslinking the electrostatic ink composition. Therefore, even if the ink coverage in the printing section 52 is high and a heat treatment such as retort heat treatment is performed, a decrease in adhesive strength can be sufficiently suppressed.

The adhesive composition can maintain high adhesive strength even after heat treatment, and also has excellent pot life. Therefore, it is also excellent in workability in coating, laminating, etc. when bonding the printed surface and the base material. The adhesive composition includes an epoxy compound, and may include a polyol and polyisocyanate that form urethane, and an epoxy compound, and at least a portion of these may become a cured product to form an adhesive layer. This allows the number of layers constituting the laminate 300 to be reduced compared to the case where an adhesive layer containing only polyurethane and an epoxy coating layer are provided separately. For this reason, for example, when producing a laminate by roll-to-roll, meandering of the roll after aging and generation of wrinkles due to blocking or the like can be suppressed. Furthermore, it is possible to reduce the aging process after coating and improve manufacturing efficiency.

In the laminates 302, 304 in which the electrostatic ink layers 50, 51 and the adhesive layer 30 on the printing surface are in direct contact, the epoxy compound contained in the adhesive composition may be an epoxy compound and/or a polyisocyanate, etc. The components fully penetrate into the electrostatic ink layers 50, 51. Thereby, the electrostatic ink compositions constituting the electrostatic ink layers 50 and 51 can be crosslinked, and the strength of the electrostatic ink compositions (electrostatic ink layers 50 and 51) can be improved. Moreover, the adhesive strength between each layer can be improved. Furthermore, even if the printing surface includes a plain area (transparent area) without the electrostatic ink layer 50 as shown in FIG. 5, the epoxy compound is contained in the adhesive layer, so it is difficult to eliminate stickiness. can. On the other hand, if an epoxy coating layer is provided separately from the adhesive layer 30, when a plain portion is included on the printed surface, the epoxy compound becomes excessive near the plain portion, and stickiness tends to occur. In this way, the laminate 300 can eliminate stickiness while adhering the printed surface including the plain portion where the printed portion 52 is not formed with high adhesive strength.

As described above, the laminates 302 and 304 can secure sufficient adhesive strength between the electrostatic ink layers 50 and 51, the base material 10, the primer layer 40, and the adhesive layer 30, so that Also, a container can be constructed in which peeling between the electrostatic ink layers 50 and 51 and the base material 10, primer layer 40, and adhesive layer 30 is suppressed. In such a container, since the adhesive state between each layer is maintained even at the bent part 60, occurrence of misalignment of the printed surface is suppressed, and the printed information on the body part 200 including the bent part 60 is not printed. can be maintained in its initial state. Even in the process of using the container, even if new bends occur due to bending of the container, the adhesion between each layer is maintained, so it maintains its functionality as a container (e.g. barrier properties, etc.) can be maintained over the period of use. Similarly, over the period of use, breakage of the container itself, deterioration of printed information, etc. can be suppressed. In such a container, even if the bent part has a printed surface, the occurrence of delamination between the laminated layers is suppressed, so the information written on the printed surface is legible and the appearance is improved. It is useful as a container for important food and drink products and sanitary products. However, the uses are not limited to these. For example, since it has excellent adhesive strength and sealing strength even after high-temperature hydrothermal treatment and retort heat treatment, it may be used as a material constituting retort containers, microwaveable containers, and boiling containers.

In the laminate according to the modified example, a primer layer 40 may be provided on each of the facing surfaces of the base material 10 and the sealant layer 20. In addition, from the viewpoint of improving the gas barrier properties and water vapor barrier properties of the laminates 302 and 304, between the base material 10 and the sealant layer 20, between the base material 10 and the primer layer 40, and/or between the sealant layer 20 and At least one of a metal layer such as an aluminum foil and a resin layer such as a nylon film may be provided between the adhesive layer 30 and the adhesive layer 30.

Specific examples of the layer structure of the laminate are illustrated below. In each example, the left end corresponds to the base material 10 and the right end corresponds to the sealant layer 20, which means that each layer is laminated in order from left to right. Also, the first adhesive layer is the adhesive layer 30, and the second adhesive layer and the third adhesive layer may be conventional adhesive layers.

(1) Transparent vapor-deposited PET film/primer layer/electrostatic ink layer/first adhesive layer/nylon layer/second adhesive layer/CPP film (unstretched polypropylene film)
(2) PET film/primer layer/electrostatic ink layer/first adhesive layer/aluminum layer/second adhesive layer/nylon layer/third adhesive layer/CPP film (unstretched polypropylene film)
(3) PET film/primer layer/electrostatic ink layer/first adhesive layer/nylon layer/second adhesive layer/CPP film (unstretched polypropylene film)
(4) PET film/primer layer/electrostatic ink layer/first adhesive layer/aluminum layer/second adhesive layer/polyethylene film

In each of the above specific examples, any layer may be provided at any position between the first adhesive layer and the sealant layer 20. (1) and (2) are suitably used as a laminate for retorts, (3) is a laminate for microwave ovens, and (4) is suitably used as a laminate whose contents are supplements or face masks. However, the uses are not limited to those mentioned above.

The above-mentioned laminate can be prepared, for example, by the following method. An embodiment of a method for manufacturing a laminate will be described below. In an example of a method for manufacturing a laminate, a laminate 302 shown in FIG. 5 is manufactured. First, a step of forming a primer layer 40 on one side of a film-like base material 10, and printing an electrostatic ink composition on the primer layer 40 to form an electrostatic ink layer 50 composed of a printed portion 52. and a step of bonding the electrostatic ink layer 50 and one side of the sealant layer 20 using the specific adhesive composition described above.

The primer layer 40 may be formed on one side of the base material 10 by flexographic printing, gravure printing, or the like. The primer layer 40 may be formed by crosslinking a resin raw material using a crosslinking agent. Crosslinking may be accomplished by irradiation with ultraviolet light, heating, ionizing radiation such as electron beam, and non-ionizing radiation such as microwave radiation.

Printing of the electrostatic ink composition can be performed by electrostatic printing using a digital printing machine.

Adhesion between the electrostatic ink layer 50 and one side of the sealant layer 20 using the adhesive composition can be performed by lamination. Lamination can be performed using any equipment. The epoxy compound contained in the adhesive composition may penetrate into the electrostatic ink composition and the primer layer 40 in which the epoxy compound and/or polyisocyanate constitute the electrostatic ink layer 50, and the electrostatic ink composition and the primer may penetrate into the electrostatic ink composition and the primer layer 40. It may also undergo a crosslinking reaction with the components contained in the layer 40. As a result, the strength of the electrostatic ink layer 50 is improved, and a laminate 300 in which the interfaces of each layer are sufficiently bonded can be obtained. During lamination, at least a portion of the adhesive composition may be cured to become a cured product. In this way, a laminate 302 comprising the base material 10, the primer layer 40, the electrostatic ink layer 50, the adhesive layer 30, and the sealant layer 20 in this order can be manufactured. The laminate 304 and the laminate according to the modified example can also be manufactured in the same manner as the laminate 302.

The laminates 302, 304 manufactured in this way have the same configuration and properties as described in these embodiments. The description of the laminates 302, 304 and their modifications also applies to the description of the embodiment of the manufacturing method described above.

[Heating packaging bag]
FIG. 7 is a plan view showing an example of the packaging bag 120 (heating packaging bag) according to one embodiment. As shown in FIG. 7, the packaging bag 120 is composed of a laminate 300 including a base material, a primer layer, an electrostatic ink layer, an adhesive layer, and a sealant layer in this order. The structure of the laminate 300 will be described later. The packaging bag 120 may be, for example, a bag that is sealed while containing an object to be packaged, such as food or drink. The packaging bag 120 may have a bent portion or may not have a bent portion.

Furthermore, the packaging bag 120 is a heating packaging bag. A heating packaging bag is a packaging bag that is intended to be subjected to heat treatment while containing an object to be packaged. The heat treatment includes "retort heat treatment," "boil heat treatment," "microwave heat treatment," and the like. The retort heat treatment is, for example, a treatment in which a filled container is heated under pressure at a temperature of 100° C. or higher, and for example, a steam method may be employed. Further, the boiling heat treatment is a treatment in which the packaging bag is heated in heated water (hot water) at a temperature of up to 100°C. Further, microwave heating treatment is a heating treatment using a so-called microwave oven, and is a treatment in which water molecules are caused to vibrate and rotate using electromagnetic waves (microwaves), thereby causing a water-containing substance to generate heat. Both treatments are often performed for the purpose of sterilizing packaging bags or packaged objects.

The packaging bag 120 is constructed by bonding the sealant layers of the pair of laminates 300 together. The packaging bag 120 includes a sealed portion 101 in which the peripheries of a pair of substantially rectangular film-like laminates 300 are pasted together (sealed), and a storage portion 124 formed between the pair of laminates 300 by the seal portion 101. Equipped with. The seal portions 101 are formed at a pair of side ends, a lower end, and an upper end of the rectangular packaging bag 120. In this way, in the packaging bag 120, the seal portion 101 is formed over the entire periphery of each of the pair of laminates 300 in which the sealant layers are stacked one on top of the other in a plan view. The storage unit 124 can store, for example, an object to be packaged (for example, food or drink). Note that in the following embodiments, a package that houses and seals an object to be packaged may be particularly referred to as a package 400. Note that the seal portion 101 at the lower end may be sealed after the storage portion 124 is filled with the object to be packaged. The seal portion 101 is configured by heat-sealing the sealant layers of the laminate 300 to each other.

Note that the pair of laminates 300 constituting the packaging bag 120 are not necessarily required to have the same layer configuration; for example, the pair of laminates may have different layer configurations.

The packaging bag 120 may include an opening means 140 to facilitate opening. The unsealing means 140 includes a pair of easy-to-open parts 144 formed in the seal part 101 at the side end, which are V-shaped notches, and a half-cut line between the pair of easy-to-open parts 144 to serve as a path for cutting. It has 141. The half-cut line 141 can be formed using a laser, for example. The easy-opening portion 144 is not limited to a V-shaped notch, but may be a U-shaped or I-shaped notch, or may have a group of scars.

The procedure for manufacturing the packaging bag 120 and the packaging body 400 using the laminate 300 will be described below. A pair of laminates 300 molded into a predetermined shape are prepared. The sealant layers provided on one side of each laminate 300 are made to face each other, and the sealant layers are bonded together. At this time, by forming the seal part 101 at the pair of side ends and the lower end (or upper end), the seal part 101 with three of the four sides closed is formed, and the inside thereof A non-sealed portion is formed. As a result, a packaging bag 130 as shown in FIG. 8 is obtained in which only the upper end (or only the lower end) is not sealed.

Next, the object to be packaged is filled into the storage section 132 of the packaging bag 130 from the unsealed upper end (or lower end). Thereafter, the sealant layers of the laminate 300 are adhered to each other at the unsealed upper end (or lower end) to form the seal portion 101 at the upper end (or lower end). As a result, a packaging body 400 including the packaging bag 120 and the object to be packaged accommodated therein can be manufactured.

As described above, the packaging bag 120 described above is a packaging bag that can be used when an object to be packaged is housed, that is, when the packaging body 400 is expected to be subjected to heat treatment. According to the above-described heat treatment, the packaging bag 120 itself is heated, and therefore, resistance to heat is required. Furthermore, in any heat treatment, water molecules are present in the vicinity in a high-temperature environment, so water resistance at high temperatures is required. Further, since the packaging bag 120 is subjected to heat treatment while containing the object, it is thought that the seal portion 101 is particularly susceptible to the influence of the heat treatment. In response to these demands, the packaging bag 120 has improved water resistance and heat resistance as a laminate by constructing each layer of the laminate 300 by combining specific materials. Further, as for the packaging bag 120, by making a part of the structure of the laminate 300 in the sealing part 101 satisfy a specific condition, damage to the packaging bag 120 in the sealing part 101 can be prevented especially during heat treatment. .

Next, as the laminate 300 constituting the packaging bag 120, the laminates 302 and 304 described as the constituent materials of the container described above can be used, and the explanation can be applied unless otherwise specified. For example, as the materials constituting each layer, the materials exemplified in the description of the corresponding layer in the above description of the container can be used. An example in which the above-described laminate 302 is used as the laminate 300 will be described below.

Primer layer 40 may contain resin. When the packaging bag 120 is used for heating, the resin preferably includes polyethyleneimine resin. In addition to polyethyleneimine resin, the primer layer 40 may also contain, for example, polyvinyl alcohol resin, cellulose resin, polyester, polyamine, polyamide resin, polyurethane, polyacrylic polymer, hydroxyl group-containing resin, carboxyl group-containing resin, and amine polymer. It may further contain resins such as. By providing the primer layer 40 containing polyethyleneimine resin on the substrate to be printed, the laminate 302 with improved water resistance and suitable for heat treatment can be produced. The content of the polyethyleneimine resin in the primer layer 40 may be 80% by mass or more, 90% by mass or more, or 97% by mass or more. The coating amount of the resin constituting the primer layer 40 may be, for example, 0.01 to 1.5 g/m ² or 0.05 to 1.0 g/m ² .

The laminate 302 includes a printed portion 52 on one of the pair of main surfaces of the primer layer 40 (printed surface) closer to the sealant layer 20 . An electrostatic ink layer 50 is provided on the printing surface. The electrostatic ink layer 50 is made of an electrostatic ink composition, and is provided by electrostatic printing using a digital printing machine. In FIG. 5, the plurality of printed parts 52 may have the same composition, or may have different colors due to having different compositions. The electrostatic ink layer 50 may be comprised of printed parts 52 provided so as to be scattered on the primer layer 40, or may be comprised of printed parts 52 provided so as to cover the entire one side of the primer layer 40. may be configured.

When the packaging bag 120 is used for heating, the ink coverage of each printed portion 52 constituting the electrostatic ink layer 50 may be 100 to 400%. By setting the ink coverage of the printing section 52 within the above range, the laminate has excellent lamination strength, and printing using a plurality of inks is possible, making it possible to correspond to various types of printing.

As described above, the laminate 300 (302, 304) can ensure sufficient adhesive strength between the electrostatic ink layers 50, 51, the base material 10, the primer layer 40, and the adhesive layer 30. Therefore, when the laminate 300 is used as a heating packaging bag and heat treatment is performed, peeling occurs between the electrostatic ink layers 50, 51, the base material 10, the primer layer 40, and the adhesive layer 30. is suppressed.

When the packaging bag 120 is used for heating, specific examples of the layered structure of the laminate are illustrated below. In each example, the left end corresponds to the base material 10 and the right end corresponds to the sealant layer 20, which means that each layer is laminated in order from left to right. Also, the first adhesive layer is the adhesive layer 30, and the second adhesive layer and the third adhesive layer may be conventional adhesive layers.

(5) Transparent vapor-deposited PET film/primer layer/electrostatic ink layer/first adhesive layer/nylon layer/second adhesive layer/CPP film (unstretched polypropylene film)
(6) PET film/primer layer/electrostatic ink layer/first adhesive layer/aluminum layer/second adhesive layer/nylon layer/third adhesive layer/CPP film (unstretched polypropylene film)
(7) Nylon layer/primer layer/electrostatic ink layer/first adhesive layer/LLDPE (linear low density polyethylene) film (8) PET film/primer layer/electrostatic ink layer/first adhesive layer/ Nylon layer/second adhesive layer/CPP film

In each of the above specific examples, any layer may be provided at any position between the first adhesive layer and the sealant layer 20. The above (5) and (6) are mainly used for packaging bags that are expected to be subjected to retort heat treatment, (7) are mainly used for packaging bags that are expected to be subjected to boiling heat treatment, and (8) is mainly used for packaging bags that are expected to undergo microwave heating treatment. However, the uses are not limited to those described above.

The above-mentioned laminate can be prepared based on the same manufacturing method as the laminate as a constituent material of the above-mentioned container.

[Effect]
As explained in the above embodiment, the packaging bag 120 (heating packaging bag) according to the present embodiment is a laminate in which the base material 10, the primer layer 40, the adhesive layer 30, and the sealant layer 20 are laminated in this order. 300. Further, the adhesive layer 30 includes at least one of an adhesive composition containing an epoxy compound and a cured product of the adhesive composition. Further, from the viewpoint of improving water resistance, the primer layer 40 may contain polyethyleneimine resin.

Electrostatic ink compositions produced by digital printers tend to have poorer heat resistance and strength than other inks. For this reason, when a laminate having an electrostatic ink layer derived from an electrostatic ink composition is applied to a packaging bag for heat treatment, there is a possibility that the packaging bag may be damaged. On the other hand, according to the above structure, the deformation of the laminate due to heating etc. is suppressed by curing the adhesive composition containing the epoxy compound. A packaging bag is obtained. In addition, when the primer layer contains polyethyleneimine resin, water resistance is also improved, and in particular, sufficient resistance to heat treatment in an environment where a large amount of moisture exists, such as boil heat treatment or retort heat treatment, is obtained. It will be done.

Moreover, the packaging bag 120 (packaging bag for heating) includes a sealing part 101 on the outer periphery that adheres the sealant layers 20 of the two laminates 300 to each other. Further, in the seal portion 101, the ink coverage of the electrostatic ink layer 50 may be 300% or less. Since the seal portion 101 is an area where thermal adhesive processing such as heat sealing is performed, the possibility of damage is higher than other areas. On the other hand, by setting the ink coverage of the electrostatic ink layer within the above range, it is possible to ensure more sufficient resistance to heat treatment for the sealing part as well, resulting in stronger resistance to heat treatment. A heating packaging bag can be obtained.

The epoxy compound may include a difunctional alicyclic epoxy compound. Since such an epoxy compound is bifunctional, it increases the number of crosslinking points with the electrostatic ink composition and firmly adheres to the printed surface.

Further, the adhesive composition may further contain a polyol, the polyol may contain an aliphatic polyester polyol, and the epoxy compound may contain an epoxy compound having epoxy groups at both ends. Such an adhesive layer 30 has high adhesive strength even in a high temperature environment. Therefore, when a packaging bag is produced by combining the laminate 300, it is possible to sufficiently prevent the electrostatic ink composition from breaking or the packaging bag from being damaged.

The adhesive composition may further contain a polyisocyanate, and the polyisocyanate may include a xylylene diisocyanate derivative. Such polyisocyanates and polyols have excellent reactivity. This improves the curability of the adhesive composition, so deformation of the laminate 300 and the packaging bag can be suppressed.

The laminate 300 (302, 304) and packaging bag manufactured in this manner have the same configuration and properties as described in these embodiments. The description of the laminate 300, the packaging bag, and their modifications also applies to the description of the embodiment of the manufacturing method described above.

Although several embodiments have been described above, the explanations of each embodiment can be applied to common configurations. Further, the present disclosure is not limited to the above embodiments.

The contents of 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 Examples below.

(Example I-1)
[Preparation of laminate]
As a base material, an alumina-deposited PET film (manufactured by Toppan Printing Co., Ltd., trade name: GLARH12, thickness: 12 μm) was prepared. A primer layer was formed by applying an aqueous primer resin (resin containing polyethyleneimine, manufactured by Michelman, trade name: DP050) to the alumina-deposited surface. The aqueous polyethyleneimine was applied in an amount of 0.10 to 0.18 g/m ² .

Predetermined printing was performed on the surface of the primer layer using a digital printing machine (manufactured by HP, Indigo 20000 digital printing machine for labels and packages). As the electrostatic ink composition, an electrostatic ink composition (HP Indigo Electroink) containing a thermoplastic resin containing a copolymer of ethylene acrylic acid and ethylene methacrylic acid was used. As shown in Table 1, yellow (Y), magenta (M), and cyan (C) were used as the colors of the electrostatic ink composition. A plurality of samples with different colors and ink coverages of electrostatic ink compositions were prepared. The ink coverage was as shown in Table 1. The coverage of each ink was adjusted by the settings of the digital printing machine. The total ink coverage was 200%.

The main ingredient is an aliphatic polyester polyol (manufactured by Mitsui Chemicals, Inc., product name: Takelac A626, hereinafter sometimes referred to as "(A)"), and the curing agent is polyisocyanate (manufactured by Mitsui Chemicals, Inc., product name: Takenate A50). , hereinafter sometimes referred to as "(B)"), 3',4'-epoxycyclohexylmethyl-3,4 epoxycyclohexane carboxylate (hereinafter sometimes referred to as "C") as an epoxy compound, and , ethyl acetate was blended as a solvent to prepare an adhesive composition having a solid content concentration of 36.5% by mass. The structure of this epoxy compound is as shown in the following formula (1). The mass-based compounding ratio (mass basis) of each component was (A):(B):(C)=8:1:0.28.

The adhesive composition prepared as described above was applied to the printed surface printed with the electrostatic ink composition using a dry laminating device to form an adhesive layer. The coating amount of the adhesive composition was 4.0 g/m ² .

A laminate film was prepared by bonding a nylon film and an unstretched polypropylene film together using a commercially available adhesive. Using the dry laminating apparatus described above, the nylon film and the adhesive layer were bonded together, with the adhesive layer on the base material and the nylon film of the laminated film facing each other, to obtain a laminate. The curing time (aging) was 2 days at 40°C.

(Comparative Example I-1)
A laminate was prepared in the same manner as in Example I-1, except that the epoxy compound (component (C)) was not blended when preparing the adhesive composition.

<Evaluation of peeling suppression performance of laminate part 1>
Each of the laminates prepared in Example I-1 and Comparative Example I-1 was evaluated for peeling suppression performance during heating. Specifically, the laminate was folded in half to form a bent part and secured with a clip as an evaluation sample, and the evaluation sample was heated for 45 minutes at the heating temperature listed in Table 1. This was done by observing the condition of the bent portion of the sample for subsequent evaluation using an optical microscope. Evaluation was performed based on the following criteria. The results are shown in Table 1.
A: No peeling is observed.
B: Slight gaps are observed between the laminated layers.
C: Peeling between laminated layers is observed.

As shown in Table 1, it was confirmed that in the laminate of Example I-1, by using a predetermined adhesive composition, sufficient peeling suppressing performance was exhibited even at bent portions. In the laminate of Comparative Example I-1, it is presumed that the resin component of the electrostatic ink layer melted, causing peeling. Furthermore, in Comparative Example I-1, it was confirmed that this tendency became more pronounced as the heating temperature increased. On the other hand, in the laminate of Example I-1, it was confirmed that sufficient peeling suppression performance was maintained even when heated. The laminate of Example I-1 is also expected to have a sufficient peeling suppressing effect even in non-thermal conditions (for example, room temperature) when the resin component is solidified.

<Evaluation of peeling suppression performance of laminate part 2>
For each of the laminates prepared in Example I-1 and Comparative Example I-1, heating was performed in the same manner as in "Evaluation of peeling suppression performance of laminate Part 1" above, except that the heating temperature and heating time were changed. The peeling suppression performance was evaluated. The results are shown in Table 2.

As shown in Table 2, even when the heating temperature and heating time were changed, the same tendency as in the above "Evaluation of Peeling Suppression Performance of Laminate Part 1" was confirmed. As shown by the results of the laminate of Example I-1, the container according to the present disclosure is sufficiently resistant to retort heat treatment at 120°C or higher (for example, heat and pressure sterilization treatment at 120°C for 30 minutes). It was confirmed that it has good resistance.

<Heat sealing test at bent parts: Evaluation of peeling suppression performance part 3>
Next, we evaluated the influence of the seal with the bent portion provided. Three sheets of each of the laminates prepared in Example I-1 and Comparative Example I-1 were prepared, and a standing pouch (container having the same structure as the container shown in FIGS. 3 and 4) composed of three of the same laminates was prepared. ) was prepared. Specifically, a sheet that would become the bottom sheet was folded in two and placed between two laminates that would be the side sheets, and a pressure of 0.2 MPa was applied to the laminate using a thermal gradient tester. , for 1 second at the temperatures shown in Table 3, and sealed. In addition, when the laminate serving as the bottom sheet portion of the standing pouch was mountain-folded, it was arranged so that the sealant layer side was on the inside of the container. As the thermal gradient tester, "HG-100" (product name) manufactured by Toyo Seiki Seisakusho Co., Ltd. was used. After preparation, a cross section of the standing pouch including the bottom sheet portion was observed using an optical microscope. As the evaluation criteria, the same criteria as in the above-mentioned "Evaluation of peeling suppression performance of laminate, Part 1" were used. The results are shown in Table 3. For reference, FIG. 9 shows the appearance of the bent portion of the laminate serving as the bottom sheet of Example I-1 and Comparative Example I-1 before sealing and after sealing at 210°C.

As shown in Table 3, peeling was sufficiently suppressed in the laminate prepared in Example I-1 even during heat treatment under pressure, such as when bonding sealant layers together. confirmed.

<Heat sealing test at bent parts: Evaluation of peeling suppression performance part 4>
The pressure conditions applied during sealing or the time during sealing were changed, and the same evaluation as in the above-mentioned "Heat sealing test at bent portion: evaluation of peeling suppression performance 3" was performed. The results are shown in Tables 4 and 5, and FIGS. 10 and 11.

As shown in Tables 4 and 5, as well as Figures 10 and 11, the laminate of Example I-1 has no heat resistance under typical sealing conditions when manufacturing containers by sealing the laminate. It was confirmed that peeling was sufficiently suppressed even under sealing conditions.

From the results of Example I-1 and Comparative Example I-1 above, it was confirmed that by using an adhesive composition containing an epoxy compound, the effect of suppressing peeling between each layer constituting the laminate is sufficiently exhibited. It was done. It is thought that the factors contributing to such a peeling suppressing effect are the improvement in the strength of the electrostatic ink composition and the improvement in the adhesive strength between each layer. For reference, examples of adjusting the composition of the adhesive composition will be shown below.

(Reference example I-1)
[Preparation of laminate]
A laminate was prepared in the same manner as in Example I-1, except that the mass-based compounding ratio of each component in the adhesive composition was changed to (A):(B):(C) as shown in Table 5. Created. Furthermore, the laminate strength of the obtained laminate was measured by the method described below. The results are shown in Table 6.

<Evaluation of laminate strength of laminate>
The laminate strength of the laminate prepared in Reference Example I-1 was measured in accordance with the description in JIS K 6854-1:1999. Specifically, the prepared laminate was first cut into a 15 mm width to prepare a measurement sample. After peeling off the layers at the ends of the measurement sample, the peel strength between the layers of the laminate was measured using a tensile tester at an angle of 90°, a tensile speed of 300 mm/min, and room temperature. This peel strength was defined as the laminate strength at room temperature (20°C). The measurement results were as shown in Table 6.

(Reference example I-2)
A first liquid consisting of aliphatic polyester polyol (A) (manufactured by Mitsui Chemicals, Inc., trade name: Takelac A626), polyisocyanate (B) (manufactured by Mitsui Chemicals, Inc., trade name: Takenate A50) and an epoxy compound (C A two-component adhesive was prepared in which a second solution consisting of (1) and (1) were separately housed in containers. The first liquid and the second liquid were mixed to prepare an adhesive composition having the formulation shown in Table 6. A laminate was prepared in the same manner as in Reference Example I-1 except that this adhesive composition was used, and the adhesive strength was measured. The measurement results were as shown in Table 6.

(Comparative Example I-2)
A laminate was prepared in the same manner as in Reference Example I-1, except that the epoxy compound (C) was not blended when preparing the adhesive composition, and the adhesive strength was measured. The measurement results were as shown in Table 6.

(Comparative Example I-3)
The epoxy compound of formula (1) was applied to the printed surface printed with the electrostatic ink composition to form an epoxy coating layer, and the adhesive composition of Comparative Example I-2 was applied to this epoxy coating layer. A laminate was produced in the same manner as in Reference Example I-1 except for the above, and the adhesive strength was measured. The coating amount of the epoxy coating layer was an amount corresponding to 0.53 parts by mass in the formulation shown in Table 5. The measurement results were as shown in 6.

The [(B)/(A)]×100 column in Table 6 shows the amount (parts by mass) of polyisocyanate to be blended with respect to 100 parts by mass of aliphatic polyester polyol. The [(C)/(A)]×100 column in Table 6 shows the amount (parts by mass) of the epoxy compound to be blended with respect to 100 parts by mass of aliphatic polyester polyol. The "Epoxy group/Isocyanate group" column in Table 6 shows the molar ratio of the epoxy group contained in the epoxy compound (C) to the isocyanate group contained in the polyisocyanate (B).

As shown in Table 6, the laminates of Reference Examples I-1 to I-2 in which an adhesive layer containing an epoxy compound and a printed surface were bonded were compared with those in which an adhesive layer not containing an epoxy compound was bonded to a printed surface. It was confirmed that the adhesive strength was higher than that of the laminate of Example I-2. In Comparative Example I-3, relatively high adhesive strength was obtained, but the number of steps was increased because an epoxy coating layer was formed in addition to the adhesive layer. It took two days for the epoxy coating layer to harden (age), reducing productivity.

In the laminate of Comparative Example I-2, peeling occurred near the interface between the electrostatic ink layer and the primer layer. In the laminate of Comparative Example I-3, the electrostatic ink layer had cohesive failure. On the other hand, the laminates of Reference Examples I-1 and I-2 exhibited sufficient laminate strength, and when a load was applied, they did not peel off at the interface between the electrostatic ink layer and the adhesive layer. , no cohesive failure of the electrostatic ink layer was observed. This suggests that the cohesive force of the electrostatic ink layer is improved. In addition, in Reference Examples I-1 to I-2, the molar ratio of the isocyanate groups contained in the polyisocyanate (B) to the hydroxyl groups of the aliphatic polyester polyol (A) was within the range of 0.5 to 10.

Next, in addition to the laminate strength, hot water laminate strength and seal strength were measured for the laminates of Reference Example I-1 and Comparative Example I-3. For the measurements, two samples were used, one with a total ink coverage of 500% and one with a total ink coverage of 200%. Details of the measurement procedure are as follows.

[Measurement of hot water laminate strength]
The laminates of Reference Example I-1 and Comparative Example I-3 were each cut to a width of 15 mm to obtain samples for measurement. After peeling off the layers at the ends of the sample for measurement, the peel strength was measured using a tensile tester while immersed in hot water at 90°C. That is, the peeling angle was set to be free, and the tensile speed was set to 300 mm/min. This peel strength is shown in Table 7 as hot water laminate strength.

[Measurement of seal strength (before heat treatment)]
Using a pair of laminates of Reference Example I-1, heat sealing was performed so that the non-stretched polypropylene films overlapped each other to form a sealed portion. In this way, the non-stretched polypropylene films were thermally welded to each other, and a measurement sample with a width of 15 mm was produced. The seal strength at the seal portion 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 conditions of a peel angle: 90°, a tensile speed: 300 mm/min, and room temperature (20° C.). This peel strength was defined as the seal strength "before heat treatment." The measurement results were as shown in Table 7. A similar measurement sample was prepared using the laminate of Comparative Example I-3, and the same measurement was performed. The measurement results were as shown in Table 7.

[Measurement of seal strength (after boiling)]
The measurement sample prepared in the above-mentioned "Measurement of seal strength (before heat treatment)" was heated in water at 100° C. for 30 minutes. Thereafter, the seal strength was measured using the same procedure as in the above-mentioned "Measurement of seal strength (before heat treatment)". The measurement results were as shown in the "After boiling" column of Table 7.

[Measurement of seal strength after retorting (120°C)]
The measurement sample prepared in the above-mentioned "Measurement of seal strength (before heat treatment)" was subjected to retort heat treatment (120° C. x 30 minutes). Using a tensile tester, the peel strength was measured in the same manner as in "Measurement of seal strength (before heat treatment)". The measurement results were as shown in the column of "120°C x 30 minutes" in Table 7.

[Measurement of seal strength after retorting (130°C)]
The measurement sample prepared in the above-mentioned "Measurement of seal strength (before heat treatment)" was subjected to retort heat treatment (130° C. x 30 minutes). Using a tensile tester, the peel strength was measured in the same manner as in "Measurement of seal strength (without heat treatment)". The measurement results were as shown in the column of "130°C x 30 minutes" in Table 7.

As shown in Table 7, the hot water laminate strength was significantly higher in Reference Example I-1 than in Comparative Example I-3. It was also confirmed that the seal strength of Reference Example I-1 was superior to that of Comparative Example I-3. In particular, the seal strength of Reference Example I-1 was sufficiently high even after boiling, whereas the seal strength of Comparative Example I-3 significantly decreased after boiling. It was confirmed that the laminate strength and seal strength of the laminate of Comparative Example I-3 were significantly reduced when heated in the presence of moisture.

(Example II-1)
[Preparation of laminate]
A nylon film (thickness: 15 μm) was prepared as a base material. A primer layer was formed by coating one main surface of this nylon film with an aqueous primer resin (resin containing polyethyleneimine, manufactured by Michelman, trade name: DP050). The aqueous polyethyleneimine was applied in an amount of 0.10 to 0.18 g/m ² .

Predetermined printing was performed on the surface of the primer layer using a digital printing machine (manufactured by HP, Indigo 20000 digital printing machine for labels and packages). As the electrostatic ink composition, an electrostatic ink composition (HP Indigo Electroink) containing a thermoplastic resin containing a copolymer of ethylene acrylic acid and ethylene methacrylic acid was used. As shown in Table 8, white (W) and cyan (C) were used as the colors of the electrostatic ink compositions. A plurality of samples with different colors and ink coverages of electrostatic ink compositions were prepared. The ink coverage was as shown in Table 8. The coverage of each ink was adjusted by the settings of the digital printing machine. As shown in Table 8, the total ink coverage was 100-300%.

The main ingredient is an aliphatic polyester polyol (manufactured by Mitsui Chemicals, Inc., product name: Takelac A626, hereinafter sometimes referred to as "(A)"), and the curing agent is polyisocyanate (manufactured by Mitsui Chemicals, Inc., product name: Takenate A50). , hereinafter sometimes referred to as "(B)"), 3',4'-epoxycyclohexylmethyl-3,4 epoxycyclohexane carboxylate (hereinafter sometimes referred to as "C") as an epoxy compound, and , ethyl acetate was blended as a solvent to prepare an adhesive composition having a solid content concentration of 36.5% by mass. The structure of this epoxy compound is as shown in the following formula (1). The mass-based compounding ratio (mass basis) of each component was (A):(B):(C)=8:1:0.28.

The adhesive composition prepared as described above was applied to the printed surface printed with the electrostatic ink composition using a dry laminating device to form an adhesive layer. The coating amount of the adhesive composition was 4.0 g/m ² .

An LLDPE film (manufactured by Futamura Chemical Co., Ltd., trade name: XMTN, thickness: 60 μm) was prepared, and the adhesive layer on the base material and the above LLDPE film were bonded together using the above dry laminating device to obtain a laminate. . The curing time (aging) was 2 days at 40°C.

(Example II-2, II-3)
A laminate was prepared in the same manner as in Example II-1, except that the color and ink coverage of the electrostatic ink composition were changed as shown in Table 8.

(Comparative Examples II-1 to II-3)
Laminates were prepared in the same manner as in Examples II-1 to II-3, except that the epoxy compound (component (C)) was not blended when preparing the adhesive composition.

[Creation of packaging]
For each of the above Examples II-1 to II-3 and Comparative Examples II-1 to II-3, two rectangular laminates of 150 mm x 200 mm were prepared. At this time, the laminates of Example II-1 and Comparative Example II-1 were prepared in which the electrostatic ink composition was not coated on the outer periphery with a width of 10 mm, and Examples II-2 to II- The laminates of No. 3 and Comparative Examples II-2 to II-3 were prepared in which the antistatic ink composition was also applied to the outer periphery. By stacking two laminates with the main surfaces on the LLDPE film side facing each other and pasting together a pair of ends along the longitudinal direction and one end along the transverse direction by heat sealing, Seal portions were formed on three of the four sides around the laminate. FIG. 12 shows the main surface of the laminate 310. First, seal portions 111 were formed on three sides of the laminate 310 by initial heat sealing to create a packaging bag with three sides closed. The width T (see FIG. 12) of the seal portion 111 at this time was 10 mm. A seal portion 114 was also formed on one side where the seal portion 111 was not formed by bonding the two laminates together by heat sealing. The width T of the seal portion 114 was also set to 10 mm. In other words, when the laminates of Example II-1 and Comparative Example II-1 are used, the packaging bag has no electrostatic ink composition printed inside the laminate in the seal portions 111 and 114. prepared.

Note that before the seal portion 114 was completely sealed to make the inside hermetically sealed, 500 ml of water was introduced as the contents inside the packaging bag. In this way, packages according to Examples II-1 to II-3 and Comparative Examples II-1 to II-3 were created. As mentioned above, the inside of the package was filled with 500 ml of water.

<Evaluation of lamination strength (before boiling)>
The laminate strength of each of the packages according to Examples II-1 to II-3 and Comparative Examples II-1 to II-3 was measured in accordance with the description of JIS K 6854-1:1999. Specifically, instead of the packages according to Examples II-1 to II-3 and Comparative Examples II-1 to II-3 that were prepared first, Examples II-1 to II-3 before filling with water The laminates according to Comparative Examples II-1 to II-3 were cut into 15 mm width samples to be used as measurement samples. After peeling off the layers at the ends of the measurement sample, the peel strength between the layers of the laminate was measured using a tensile tester at an angle of 90°, a tensile speed of 300 mm/min, and room temperature. This peel strength was defined as the laminate strength at room temperature (20°C). The measurement results were as shown in Table 8.

<Evaluation of lamination strength (after boiling)>
Each of the packages according to Examples II-1 to II-3 and Comparative Examples II-1 to II-3 was heated in water at 90° C. for 30 minutes (boiling heat treatment). Thereafter, a part of the package was cut out in the same manner as in <Evaluation of lamination strength (before boiling)> described above, and the lamination strength was measured. The measurement results were as shown in Table 8.

From the above results, it was confirmed that the presence of the electrostatic ink layer reduced the laminate strength compared to the case where the electrostatic ink layer was not present (Example II-1, Comparative Example II-1). It was also confirmed that as the ink coverage increased, the laminate strength decreased. In particular, when the ink coverage reaches 300%, the laminate strength of Comparative Example II-3 becomes 2 or less both before and after boiling and in the package (laminate), and the packaging bag for heat treatment becomes It has been confirmed that there is a possibility that it cannot withstand the use as a material. Note that in all of Examples II-1 to II-3 and Comparative Examples II-1 to II-3, the laminate strength was increased after boiling. This is presumed to be due to the progress of the reaction of isocyanate as a curing agent contained in the adhesive composition during boiling.

<Evaluation of seal strength (before boiling)>
For each of the packages according to Examples II-1 to II-3 and Comparative Examples II-1 to II-3, before filling with water (before completely sealing the seal portion 114 to seal the inside) ) was cut out to include the seal portion to prepare a measurement sample with a width of 15 mm. The seal strength at the seal portion 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 conditions of a peel angle: 90°, a tensile speed: 300 mm/min, and room temperature (20° C.). This peel strength was defined as the seal strength "before heat treatment." The measurement results were as shown in Table 9.

<Evaluation of seal strength (after boiling)>
Each of the packages according to Examples II-1 to II-3 and Comparative Examples II-1 to II-3 was heated in water at 90° C. for 30 minutes (boiling heat treatment). Thereafter, the package was opened, the water filled inside was removed, and after A, the seal strength was measured using the same procedure as in the above-mentioned "evaluation of seal strength (before boiling)". The measurement results were as shown in Table 9.

Note that "film breakage" in Table 9 indicates that the measurement was completed with the film broken. Moreover, "triangular peeling" refers to a state in which peeling occurs between layers in at least one of a pair of laminates. Furthermore, "edge breakage" refers to a state in which damage occurs at the boundary between the heat-sealed part and the inner side of the bag.

From the above results, it was confirmed that the presence of the electrostatic ink layer reduces the sealing strength compared to the case where the electrostatic ink layer is not present (Example II-1, Comparative Example II-1). It was also confirmed that as the ink coverage increased, the seal strength decreased. Regarding Comparative Examples II-2 and II-3, the seal strength before and after boiling is 40 N/15 mm or less, so it is possible that the bags cannot withstand use as packaging bags for heat treatment. It was confirmed that there is a

<Air-containing boil test>
For each of the above-mentioned Examples II-1 to II-3 and Comparative Examples II-1 to II-3, two rectangular laminates of 150 mm x 200 mm were prepared and processed in the same manner as in the preparation of the above-mentioned packaging. A package for the air-containing boil test was prepared.

Note that before completely sealing the seal portion 114 to make the inside hermetically sealed, 300 ml of water was introduced into the packaging bag, and then 100 ml of air was added, which improved the laminate strength and Different from packaging for seal strength. In this way, packages for air-containing boil tests according to Examples II-1 to II-3 and Comparative Examples II-1 to II-3 were prepared. As mentioned above, the inside of the package was filled with 300 ml of water and 100 ml of air.

Three packages each of Examples II-1 to II-3 and Comparative Examples II-1 to II-3 were prepared, and each was heated in water at 100° C. for 60 minutes. The surface of the package after heating was visually observed to see if there was any lifting of the printed surface due to the electrostatic ink composition on the surface of the laminate. The measurement results were as shown in Table 10.

From the results of the above-mentioned Examples and Comparative Examples, it was confirmed that by using an adhesive composition containing a polyol, a polyisocyanate, and an epoxy compound, it has resistance to heat treatment. It is thought that improvements in the strength of the electrostatic ink composition and improvements in adhesive strength between each layer contribute to this improvement in resistance to heat treatment. In order to verify these improving effects, the following experiment was conducted.

(Reference Example II-1)
[Preparation of adhesive composition and laminate]
A polyethylene terephthalate film (PET film, thickness: 12 μm) was prepared as a base material. The same aqueous primer resin as in Example II-1 was applied to one side of this PET film to form a primer layer. The amount of aqueous polyethyleneimine applied was also the same as in Example II-1.

Using the digital printing machine used in Example II-1, predetermined printing was performed on the surface of the primer layer. As the electrostatic ink composition, an electrostatic ink composition (HP Indigo Electroink) containing a thermoplastic resin containing a copolymer of ethylene acrylic acid and ethylene methacrylic acid was used. As shown in Table 11, the colors of the electrostatic ink compositions used were white (W), yellow (Y), magenta (M), and cyan (C). A plurality of samples with different colors and ink coverages of electrostatic ink compositions were prepared. The ink coverage of each color and its total were as shown in Table 11. As shown in Table 11, the total ink coverage was 200-500%.

The same adhesive composition as in Example II-1 was prepared, and the adhesive composition was applied to the printed surface in the same manner as in Example II-1 to form an adhesive layer. The coating amount of the adhesive composition was 4.0 g/m ² .

A laminated film containing aluminum foil (manufactured by Toyo Aluminum Co., Ltd., thickness: 7 μm), a nylon film, and an unstretched polypropylene film in this order was prepared. Using the same dry laminating apparatus as in Example II-1, the aluminum foil and the adhesive layer were bonded together so that the adhesive layer on the base material and the aluminum foil of the laminated film faced each other to obtain a laminate. The curing time (aging) was 2 days at 40°C.

[Measurement of adhesive strength (room temperature)]
The adhesive strength of the produced laminate was measured in accordance with JIS K 6854-1:1999. Specifically, the produced laminate was cut into a 15 mm width to prepare a measurement sample. After peeling off the layers at the ends of the measurement sample, the peel strength between the layers of the laminate was measured using a tensile tester at an angle of 90°, a tensile speed of 300 mm/min, and room temperature. This peel strength was defined as the adhesive strength at room temperature (20°C). The measurement results were as shown in Table 11.

(Reference Examples II-2 to II-6)
A laminate was produced in the same manner as in Reference Example II-1, except that the formulation of the adhesive composition was changed as shown in Tables 11 and 12, and the adhesive strength was measured. The measurement results were as shown in Tables 11 and 12.

(Reference Example II-7)
A first liquid consisting of aliphatic polyester polyol (A) (manufactured by Mitsui Chemicals, Inc., trade name: Takelac A626), polyisocyanate (B) (manufactured by Mitsui Chemicals, Inc., trade name: Takenate A50) and an epoxy compound (C A two-component adhesive was prepared in which a second solution consisting of (1) and (1) were separately housed in containers. The first liquid and the second liquid were mixed to prepare an adhesive composition having the formulation shown in Table 12. A laminate was prepared in the same manner as in Reference Example II-1 except that this adhesive composition was used, and the adhesive strength was measured. The measurement results were as shown in Table 12.

(Comparative Example II-4)
A laminate was prepared in the same manner as in Reference Example II-1, except that the epoxy compound (C) was not blended when preparing the adhesive composition, and the adhesive strength was measured. The measurement results were as shown in Table 12.

(Comparative Example II-5)
The epoxy compound of formula (1) was applied to the printed surface printed with the electrostatic ink composition to form an epoxy coating layer, and the adhesive composition of Comparative Example II-4 was applied to this epoxy coating layer. A laminate was produced in the same manner as in Reference Example II-1 except for the above, and the adhesive strength was measured. The coating amount of the epoxy coating layer was an amount corresponding to 0.53 parts by mass in the formulation shown in Table 11. The measurement results were as shown in Table 12.

The [(B)/(A)] x 100 column in Tables 11 and 12 shows the blending amount (parts by mass) of polyisocyanate relative to 100 parts by mass of aliphatic polyester polyol. The [(C)/(A)] x 100 column in Tables 11 and 12 shows the blending amount (parts by mass) of the epoxy compound relative to 100 parts by mass of aliphatic polyester polyol. The "Epoxy group/Isocyanate group" column in Tables 11 and 12 shows the molar ratio of the epoxy group contained in the epoxy compound (C) to the isocyanate group contained in the polyisocyanate (B).

As shown in Tables 11 and 12, the laminates of Reference Examples II-1 to II-7 in which the adhesive layer containing an epoxy compound and the printed surface were bonded together were bonded together in the adhesive layer containing no epoxy compound and the printed surface. It was confirmed that the adhesive strength was higher than that of the bonded laminate of Comparative Example II-4. In Comparative Example II-5, relatively high adhesive strength was obtained, but the number of steps was increased because an epoxy coating layer was formed in addition to the adhesive layer. It took two days for the epoxy coating layer to harden (age), reducing productivity.

In the laminate of Comparative Example II-4, peeling occurred near the interface between the electrostatic ink layer and the primer layer. In the laminate of Comparative Example II-5, the electrostatic ink layer had cohesive failure. On the other hand, in the laminates of Reference Examples II-1 to II-7, peeling occurred at the interface between the electrostatic ink layer and the adhesive layer, and no cohesive failure of the electrostatic ink layer was observed. This suggests that the cohesive force of the electrostatic ink layer is improved. In Reference Examples II-1 to II-7, the molar ratio of the isocyanate groups contained in the polyisocyanate (B) to the hydroxyl groups of the aliphatic polyester polyol (A) was within the range of 0.5 to 10.

Next, the adhesive strength, hot water adhesive strength, and seal strength of the laminates of Reference Example II-5 and Comparative Example II-5 were measured. For the measurements, two samples were used, one with a total ink coverage of 500% and one with a total ink coverage of 200%. Details of the measurement procedure are as follows.

[Measurement of hot water adhesive strength]
The laminates of Reference Example II-5 and Comparative Example II-5 were each cut to a width of 15 mm to obtain samples for measurement. After peeling off the layers at the ends of the sample for measurement, the peel strength was measured using a tensile tester while immersed in hot water at 90°C. That is, the peeling angle was set to be free, and the tensile speed was set to 300 mm/min. This peel strength is shown in Table 13 as hot water adhesive strength.

[Measurement of seal strength (before heat treatment)]
Using a pair of laminates of Reference Example II-5, heat sealing was performed so that the non-stretched polypropylene films overlapped each other to form a sealed portion. In this way, the non-stretched polypropylene films were thermally welded to each other, and a measurement sample with a width of 15 mm was produced. The seal strength at the seal portion 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 conditions of a peel angle: 90°, a tensile speed: 300 mm/min, and room temperature (20° C.). This peel strength was defined as the seal strength "before heat treatment." The measurement results were as shown in Table 13. A similar measurement sample was prepared using the laminate of Comparative Example II-5, and the same measurement was performed. The measurement results were as shown in Table 13.

[Measurement of seal strength (after boiling)]
The measurement sample prepared in the above-mentioned "Measurement of seal strength (before heat treatment)" was heated in water at 100° C. for 30 minutes. Thereafter, the seal strength was measured using the same procedure as in the above-mentioned "Measurement of seal strength (without heat treatment)". The measurement results were as shown in the "After boiling" column of Table 13.

[Measurement of seal strength after retorting (120°C)]
The measurement sample prepared in the above-mentioned "Measurement of seal strength (before heat treatment)" was subjected to retort heat treatment (120° C. x 30 minutes). Using a tensile tester, the peel strength was measured in the same manner as in "Measurement of seal strength (before heat treatment)". The measurement results were as shown in the column of "120°C x 30 minutes" in Table 13.

[Measurement of seal strength after retorting (130°C)]
The measurement sample prepared in the above-mentioned "Measurement of seal strength (before heat treatment)" was subjected to retort heat treatment (130° C. x 30 minutes). Using a tensile tester, the peel strength was measured in the same manner as in "Measurement of seal strength (without heat treatment)". The measurement results were as shown in the column "130°C x 30 minutes" in Table 13.

As shown in Table 13, the hot water adhesive strength of Reference Example II-5 was significantly higher than that of Comparative Example II-5. It was also confirmed that the seal strength of Reference Example II-5 was superior to that of Comparative Example II-5. In particular, the seal strength of Reference Example II-5 was sufficiently high even after boiling, whereas the seal strength of Comparative Example II-5 significantly decreased after boiling. It was confirmed that the adhesive strength and sealing strength of the laminate of Comparative Example II-5 were significantly reduced when heated in the presence of moisture.

(Reference Example II-8)
[Preparation of adhesive composition and laminate]
A polyethylene terephthalate film (PET film, thickness: 12 μm) was prepared as a base material. The same aqueous primer resin as in Example II-1 was applied to one side of this PET film to form a primer layer. The amount of aqueous polyethyleneimine applied was also the same as in Example II-1.

Using the digital printing machine used in Example II-1, predetermined printing was performed on the surface of the primer layer. The colors of the electrostatic ink composition used were white (W), yellow (Y), magenta (M), and cyan (C). Ink coverages of 200% W and 100% C+100% M+100% Y+200% W were prepared. In Table 14, the former was defined as "ink coverage (1)" and the latter was defined as "ink coverage (2)". In this way, two types of samples with different ink coverage rates of electrostatic ink compositions were prepared.

Example II-1 and an adhesive composition were prepared, and the adhesive composition was applied to the printed surface in the same manner as in Example II-1 to form an adhesive layer. The coating amount of the adhesive composition was 4.0 g/m ² .

The laminated film (laminated film obtained by laminating a nylon film and an unstretched polypropylene film together using a commercially available adhesive) used in Example II-1 was treated with a base adhesive in the same manner as in Example II-1. The layers were bonded together to obtain a laminate. The curing time (aging) was 2 days at 40°C.

The seal strength (before heat treatment) and seal strength (after boiling) of the thus obtained laminate were measured. The measurement results were as shown in Table 14. In addition, adhesive strength (before heat treatment) and hot adhesive strength (120° C.) were measured according to the following procedures.

Using a pair of laminates of Reference Example II-8, heat sealing was performed so that the non-stretched polypropylene films overlapped each other to produce a three-sided bag having a sealed portion. Water was sealed in this three-sided bag. Thereafter, retort heat treatment (120° C. x 30 minutes) was performed using a retort treatment device (manufactured by Hisaka Seisakusho). After the retort heat treatment, the sample was cut to a width of 15 mm, a sample of the sealed portion was taken, and the interlayer strength between the electrostatic ink layer and the layer in contact with the electrostatic ink layer was measured. The measured peel strengths are shown in the "Hot adhesive strength (120°C)" column of Table 14. Note that Table 14 also shows the adhesive strength before retort heat treatment.

(Reference Examples II-9 to II-12)
When preparing the adhesive composition, a laminate was produced in the same manner as in Reference Example II-8, except that the amount of polyisocyanate (B) was changed as shown in Table 14. The produced laminate was evaluated in the same manner as Reference Example II-8. The evaluation results were as shown in Table 14.

(Comparative Example II-6)
A laminate was produced in the same manner as Comparative Example II-4, except that the printed surface printed with the electrostatic ink composition was laminated using a hand laminator machine without using a dry laminator. The color and ink coverage of the electrostatic ink composition were as shown in Table 14. The produced laminate was evaluated in the same manner as Reference Example II-8. The evaluation results were as shown in Table 14.

As shown in Table 14, it was confirmed that high adhesive strength and sealing strength were obtained in each reference example even under heating conditions. Additionally, it was confirmed that by adjusting the blending ratio of polyisocyanate (B) to aliphatic polyester polyol (A), hot adhesive strength (120°C) and seal strength (before heat treatment and after boiling) could be sufficiently increased. It was done. On the other hand, in Comparative Example II-6 in which the epoxy compound (C) was not used, it was confirmed that the adhesive strength and seal strength were significantly reduced when exposed to high temperature hot water treatment conditions. In addition, in Reference Examples II-8 to II-12, the molar ratio of the isocyanate groups contained in the polyisocyanate (B) to the hydroxyl groups contained in the aliphatic polyester polyol (A) was within the range of 0.5 to 10. Ta.

(Reference Examples II-13 to II-17)
Aliphatic polyester polyol (A1) (Mitsui Chemicals, Inc., Takelac A525), polyisocyanate (B1) (Mitsui Chemicals, Inc., Takenate A52), and 3',4'-epoxycyclohexylmethyl as the epoxy compound (C) An adhesive composition was prepared by blending -3,4 epoxycyclohexane carboxylate. The blending ratio was as shown in Table 15. Laminates were prepared and evaluated in the same manner as in Reference Examples II-8 to II-12, except that such adhesive compositions were used. The evaluation results were as shown in Table 15.

(Comparative Example II-7)
An adhesive composition was prepared by blending aliphatic polyester polyol (A1) (Mitsui Chemicals, Inc., Takelac A525) and polyisocyanate (B1) (Mitsui Chemicals, Inc., Takenate A52) as polyols. The blending ratio was as shown in Table 15. A laminate was produced and evaluated in the same manner as Comparative Example II-4, except that such an adhesive composition was used. The evaluation results were as shown in Table 15.

As shown in Table 15, it was confirmed that high adhesive strength and seal strength were obtained in each reference example even when the combination of aliphatic polyester polyol and polyisocyanate was changed. Additionally, it was confirmed that by adjusting the blending ratio of polyisocyanate (B1) to aliphatic polyester polyol (A1), hot adhesive strength (120°C) and seal strength (without heat treatment and after boiling) could be sufficiently increased. It was done. On the other hand, in Comparative Example II-7 in which the epoxy compound (C) was not used, it was confirmed that the adhesive strength and seal strength were significantly reduced when exposed to high temperature hot water treatment conditions. In addition, in Reference Examples II-13 to II-17, the molar ratio of the isocyanate groups contained in the polyisocyanate (B1) to the hydroxyl groups contained in the aliphatic polyester polyol (A1) was within the range of 0.5 to 10. Ta.

According to the present disclosure, although the printing surface is printed by a digital printing machine, the interface between the electrostatic ink layer and the primer layer and the adhesive between the electrostatic ink layer and the It is possible to provide a container in which peeling at the interface with the layer is suppressed.

According to the present disclosure, it is possible to provide a packaging bag that has an electrostatic ink layer produced by a digital printer and has sufficient resistance to heat treatment.

DESCRIPTION OF SYMBOLS 10... Base material, 20... Sealant layer, 30... Adhesive layer, 40... Primer layer, 50, 51... Electrostatic ink layer, 52... Printing part, 60... Bent part, 70... Spout, 72... Spout, 74...Flange, 100,110...Container, 101,103,111,114,121,122...Seal portion, 102,112,124,132...Accommodating portion, 120,130...Packaging bag, 140...Opening means, 141... Half cut line, 144...Easy-opening processed part, 200...Body part, 300, 302, 304, 306, 310... Laminated body, 400... Packaging body.

Claims (13)

A container including a body portion having a bent portion,
The body portion is composed of at least one laminate,
The laminate includes a base material, a primer layer, an adhesive layer, and a sealant layer in this order, and a printing part made of an electrostatic ink composition on at least a part of the main surface of the primer layer on the sealant layer side. the printed part is in direct contact with the adhesive layer,
The adhesive layer includes at least one of an adhesive composition containing an epoxy compound and a polyisocyanate, and a cured product thereof,
The molecular weight of the epoxy compound is 500 or less,
The epoxy compound includes a difunctional alicyclic epoxy compound,
The container, wherein the molar ratio of the epoxy groups contained in the epoxy compound to the isocyanate groups contained in the polyisocyanate is 2.4 to 10. The container according to claim 1, wherein the bent portion has the printed portion. The adhesive composition further includes a polyol,
3. The container according to claim 1, wherein the polyol includes an aliphatic polyester polyol, and the epoxy compound includes one having epoxy groups at both ends. A container according to any one of claims 1 to 3, wherein the polyisocyanate comprises a xylylene diisocyanate derivative. The container according to any one of claims 1 to 4, further comprising a spout connected to the body. 6. The container according to claim 5, wherein the spout has a cylindrical spout and a flange extending outward from a peripheral edge of a lower end of the spout. The container according to any one of claims 1 to 6, wherein the body portion is composed of one piece of the laminate. The container according to any one of claims 1 to 7, wherein the body portion is composed of two laminates serving as side sheets and one laminate serving as a bottom sheet. A packaging bag for heat treatment comprising a laminate having a base material, a primer layer, an electrostatic ink layer, an adhesive layer, and a sealant layer in this order,
the electrostatic ink layer is in direct contact with the adhesive layer;
The adhesive layer includes at least one of an adhesive composition containing an epoxy compound and a polyisocyanate, and a cured product thereof,
The molecular weight of the epoxy compound is 500 or less,
The epoxy compound includes a difunctional alicyclic epoxy compound,
A heating packaging bag, wherein the molar ratio of the epoxy group contained in the epoxy compound to the isocyanate group contained in the polyisocyanate is 2.4 to 10. The heating packaging bag according to claim 9, wherein the primer layer contains polyethyleneimine resin. including a sealing part for adhering the sealant layers of the two laminates to each other on the outer periphery,
The heating packaging bag according to claim 9 or 10, wherein the seal portion has an ink coverage of the electrostatic ink layer of 300% or less. The adhesive composition further includes a polyol,
The heating packaging bag according to any one of claims 9 to 11, wherein the polyol includes an aliphatic polyester polyol, and the epoxy compound includes one having epoxy groups at both ends. The heating packaging bag according to any one of claims 9 to 12, wherein the polyisocyanate includes a xylylene diisocyanate derivative.

Images