Printed matter and laminate, and packaging bag

Abstract

To provide a printed matter that ink is highly-precisely printed on a paper base material.SOLUTION: There is provided a printed matter 100 comprising a paper base material 10, a primer layer 20 provided on one surface 10A thereof and an electrostatic ink layer 30 covering at least part of the primer layer 20, the electrostatic ink layer 30 being made up of dots 31 having a circularity of 0.60 or greater. Besides, there is provided a printed matter 105 comprising a paper base material 10, a primer layer 20 provided on one surface 10A thereof and an electrostatic ink layer 30A covering at least part of the primer layer 20, the paper base material 10 having a surface smoothness of 8 seconds or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to printed matter, laminates, and packaging bags. [Background technology]

[0002] Packaging bags for containing and sealingly storing beverages, food products, etc. are known. Conventionally, packaging bags have been made of thin films or sheets with a polyethylene terephthalate (PET) base material, from the viewpoints of durability, printability, etc. Recently, however, the use of paper base materials as the base material for packaging bags has been considered in order to protect the environment by reducing waste plastic. For example, Patent Document 1 describes a packaging bag with excellent printability and water resistance, which has a paper base layer, a coating layer containing an inorganic filler, and ink applied by gravure printing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-130470 Summary of the Invention [Problem to be solved by the invention]

[0004] The surface of a paper substrate is less smooth than that of a PET film. Therefore, in gravure printing, in which ink filled in the recesses of a gravure plate is transferred to the paper substrate, the ink cannot be sufficiently pressed onto the paper substrate, resulting in chipping and rubbing of the ink dots. For this reason, when printing images and text information on a paper substrate using gravure printing, it was necessary to enlarge the dots to prevent chipping and rubbing after printing, making it difficult to achieve high-resolution printing on the paper substrate. Therefore, the present disclosure provides a printed material in which ink is printed on a paper substrate with high resolution. It also provides a laminate and a packaging bag including a printed material in which ink is printed on a paper substrate with high resolution. [Means for solving the problem]

[0005] One aspect of the present disclosure provides a printed matter comprising a paper substrate, a primer layer on one side thereof, and an electrostatic ink layer covering at least a portion of the primer layer, wherein the circularity of the halftone dots constituting the electrostatic ink layer is 0.60 or greater.

[0006] The printed matter has a circularity of 0.60 or more for the halftone dots constituting the electrostatic ink layer. The halftone dots in such printed matter are nearly circular, reducing chipping and rubbing of the dots. Therefore, high-resolution printing is achieved despite the paper substrate. Such printed matter offers excellent design freedom. Furthermore, the use of a paper substrate reduces environmental impact.

[0007] One aspect of the present disclosure provides a printed matter comprising a paper substrate, a primer layer on one side thereof, and an electrostatic ink layer covering at least a portion of the primer layer, wherein the surface smoothness of the paper substrate is 8 seconds or greater.

[0008] The printed matter has an electrostatic ink layer covering a primer layer on one side of a paper substrate. Therefore, the electrostatic ink is printed with high resolution even though the paper substrate has a surface smoothness of 8 seconds or more. Such printed matter offers excellent design freedom. Furthermore, the paper substrate reduces environmental impact.

[0009] One aspect of the present disclosure provides a laminate including the printed matter and an adhesive layer and a sealant layer, in this order, on the other side of the paper substrate. This laminate includes the printed matter described above. Therefore, the image and text information on the surface of the laminate are printed with high resolution. This laminate offers excellent design freedom. Furthermore, the paper substrate reduces environmental impact.

[0010] One aspect of the present disclosure provides a packaging bag configured by heat-sealing the sealant layers of the laminate. This packaging bag includes the printed matter described above. Therefore, the image and text information on the surface of the packaging bag are printed with high resolution. This allows for excellent design freedom. Furthermore, since the packaging bag includes a paper substrate, it can reduce environmental impact. [Effects of the Invention]

[0011] To provide a printed matter in which ink is printed with high resolution on a paper substrate, and to provide a laminate and a packaging bag including a printed matter in which ink is printed with high resolution on a paper substrate. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a cross-sectional view showing an example of a printed matter according to the first embodiment. [Figure 2] FIG. 10 is a cross-sectional view showing an example of a printed matter according to a second embodiment. [Figure 3] FIG. 1 is a cross-sectional view illustrating an example of a laminate according to an embodiment. [Figure 4] FIG. 10 is a cross-sectional view illustrating an example of a laminate according to another embodiment. [Figure 5] FIG. 10 is a cross-sectional view showing an example of a laminate according to yet another embodiment. [Figure 6] FIG. 1 is a plan view illustrating an example of a packaging bag according to an embodiment. [Figure 7] FIG. 10 is a perspective view showing another example of a packaging bag. [Figure 8] 1 is a photograph of the printed surface of Reference Example 1 taken using an optical microscope at 200x magnification. [Figure 9] 1 is a photograph of the printed surface of Reference Example 2 taken with an optical microscope at 200x magnification. [Figure 10] 1 is a photograph of the printed surface of Reference Example 3 taken with an optical microscope at 200x magnification. [Figure 11] 1 is a photograph of the printed surface of Reference Example 4 taken at 200x magnification using an optical microscope. [Figure 12](a) is a photograph of the printed surface of Example 1 taken with an optical microscope at a magnification of 100 times, and (b) is a photograph of the printed surface of Comparative Example 1 taken with an optical microscope at a magnification of 100 times. [Figure 13] (a) is a photograph of the printed surface of Example 2 taken with an optical microscope at a magnification of 100 times, and (b) is a photograph of the printed surface of Comparative Example 2 taken with an optical microscope at a magnification of 100 times. [Figure 14] (a) is a photograph of the printed surface of Example 3 taken with an optical microscope at a magnification of 100 times. (b) is a photograph of the printed surface of Comparative Example 3 taken with an optical microscope at a magnification of 100 times. [Figure 15] (a) is a photograph of the printed surface of Example 4 taken with an optical microscope at a magnification of 100 times, and (b) is a photograph of the printed surface of Comparative Example 4 taken with an optical microscope at a magnification of 100 times. [Figure 16] (a) is a photograph of the printed surface of Example 5 taken with an optical microscope at a magnification of 100 times, and (b) is a photograph of the printed surface of Comparative Example 5 taken with an optical microscope at a magnification of 100 times. [Figure 17] (a) is a photograph of the printed surface of Example 6 taken with an optical microscope at a magnification of 100 times. (b) is a photograph of the printed surface of Comparative Example 6 taken with an optical microscope at a magnification of 100 times. [Figure 18] (a) is a photograph of the printed surface of Example 7 taken with an optical microscope at a magnification of 100 times. (b) is a photograph of the printed surface of Comparative Example 7 taken with an optical microscope at a magnification of 100 times. [Figure 19] (a) is a photograph of the printed surface of Example 8 taken with an optical microscope at 100x magnification. (b) is a photograph of the printed surface of Comparative Example 8 taken with an optical microscope at 100x magnification. [Figure 20] (a) is a photograph of the printed surface of Example 9 taken with an optical microscope at 100x magnification. (b) is a photograph of the printed surface of Comparative Example 9 taken with an optical microscope at 100x magnification. [Figure 21](a) is a photograph of the printed surface of Example 10 taken with an optical microscope at 100x magnification. (b) is a photograph of the printed surface of Comparative Example 10 taken with an optical microscope at 100x magnification. [Figure 22] (a) is a photograph of the printed surface of Example 11 taken with an optical microscope at 100x magnification. (b) is a photograph of the printed surface of Comparative Example 11 taken with an optical microscope at 100x magnification. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings as needed. However, the following embodiments are merely examples for explaining the present disclosure and are not intended to limit the present disclosure to the following content. In the description, the same elements or elements having the same functions will be designated by the same reference numerals, and redundant description will be omitted where appropriate. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the orientation of the reference numerals shown in the drawings. Furthermore, the dimensional ratios of each element are not limited to those shown in the drawings.

[0014] Unless otherwise specified, the materials exemplified in this disclosure can be used singly or in combination of two or more. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition refers to the total amount of the multiple substances present in the composition unless otherwise specified. In this disclosure, numerical ranges indicated using "to" indicate ranges that include the respective numerical values ​​before and after "to" as minimum and maximum values. In this disclosure, individual upper and lower limit values ​​can be arbitrarily combined.

[0015] [Printed material] <First embodiment of printed matter> FIG. 1 is a cross-sectional view showing an example of a printed matter according to the first embodiment. FIG. 1 shows a cross-section along the stacking direction (thickness direction) of a printed matter 100. The printed matter 100 comprises a paper substrate 10, a primer layer 20 on one surface 10A of the paper substrate 10, and an electrostatic ink layer 30 covering at least a portion of the primer layer 20. The paper substrate 10 and the primer layer 20 are in contact with each other, and the primer layer 20 and the electrostatic ink layer 30 are in contact with each other. The electrostatic ink layer 30 is composed of discontinuous halftone dots 31, which are formed in an island shape. This provides the printed matter 100 with plain areas that are not covered by the electrostatic ink layer 30.

[0016] The circularity of the dots 31 constituting the electrostatic ink layer 30 is 0.60 or greater. The circularity of the dots 31 can be calculated using the following formula (1). The closer the circularity of the dots 31 is to 1, the more circular the dots 31 are. Therefore, if the circularity of the dots 31 is 0.60 or greater, the dots will be nearly circular with reduced chipping and rubbing, resulting in a printed matter 100 with high-resolution images or text information. Such a printed matter 100 offers excellent design flexibility. The circularity of the dots 31 can be calculated by substituting the average dot area and average dot perimeter calculated by image analysis of a photograph of the observed area of ​​the printed surface taken at 100x magnification using an optical microscope (product name: VHX-6000, manufactured by Keyence Corporation) into formula (1). Note that the circularity of the dots is calculated by excluding dots 31 that are partially obscured in the photograph of the observed area. (Circularity of halftone dots) = 4π × (average area of ​​halftone dots) / (average perimeter of halftone dots) 2 (1)

[0017] The circularity of the halftone dots 31 may be 0.70 or more, 0.80 or more, or 0.85 or more. By keeping the circularity of the halftone dots within the above range, chipping and rubbing of the halftone dots 31 are further reduced, and the shape of the halftone dots 31 becomes closer to a circle. Therefore, the printed matter 100 having such halftone dots 31 has higher definition of the image or text information, and offers greater design freedom. The circularity of the halftone dots 31 may be 1.0 or less, or 0.95 or less. For example, the range of the circularity of the halftone dots may be 0.60 to 1.0.

[0018] The type of paper substrate 10 is not particularly limited, and may be, for example, roll paper, fine paper, special fine paper, coated paper, art paper, one-sided art paper, cast coated paper, Japanese paper, imitation paper, kraft paper, bleached kraft paper, etc. Using a paper substrate can reduce the environmental impact.

[0019] The surface smoothness of the paper substrate 10 may be 8 seconds or more. Surface smoothness can be determined based on JIS P8155:2010 "Paper and Paperboard - Smoothness Testing Method - Oken Method" by pressing the paper substrate 10 against a measuring ring at a constant pressure and measuring the time it takes for a specified amount of compressed air at a constant pressure to pass through the gap between the paper substrate 10 and the measuring ring. In other words, the greater the surface smoothness, the longer it takes for air to pass through, indicating a smoother surface. On the other hand, the smaller the surface smoothness, the shorter the time it takes for air to pass through, indicating a surface with greater irregularities. A printed item 100 with a paper substrate 10 having a surface smoothness of 8 seconds or more has a highly precise electrostatic ink layer 30 printed on a paper substrate 10 with large irregularities, allowing for excellent design freedom.

[0020] The surface smoothness of the paper substrate 10 may be 9 seconds or more, or 10 seconds or more. With a surface smoothness in the above range, the electrostatic ink layer 30 can be printed on the paper substrate 10 with even higher resolution. The surface smoothness of the paper substrate 10 may be 300 seconds or less, or 250 seconds or less. With a surface smoothness in the above range, the electrostatic ink layer 30 can be printed with high resolution even on a paper substrate 10 with such large irregularities that gravure printing would cause chipping or rubbing of the halftone dots. An example of the range of the surface smoothness of the paper substrate 10 may be 8 to 300 seconds.

[0021] The basis weight (mass per unit area) of the paper substrate 10 is 100 g / m 2 If the basis weight of the paper substrate 10 is within the above range, the paper substrate 10 can be made sufficiently thin, and the printed matter 100 can be suitably used for packaging bags. From the viewpoint of further thinning the paper substrate 10 and improving its flexibility, the basis weight of the paper substrate 10 is set to 90 g / m 2 Below 80g / m 2 or less, or 70 g / m 2 In addition, the basis weight of the paper substrate 10 may be 10 g / m or less from the viewpoint of increasing the thickness of the paper substrate 10 and improving the strength of the printed matter 100. 2 More than 20g / m 2 or more, or 30 g / m 2 An example of the range of the basis weight of the paper substrate 10 is 10 to 100 g / m 2 may be.

[0022] The primer layer 20 may contain a resin. Examples of resins include polyvinyl alcohol resin, cellulose-based resin, polyester, polyamine, polyethyleneimine resin, polyamide resin, polyurethane, polyacrylic polymer hydroxyl-containing resin, carboxyl group-containing resin, and amine-based polymer. The presence of the primer layer 20 suppresses penetration of the electrostatic ink into the paper substrate 10, and increases the adhesive strength of the electrostatic ink compared to printing the electrostatic ink directly on the paper substrate 10. This allows smooth printing of the electrostatic ink composition using a digital printer. Furthermore, the adhesion of the electrostatic ink layer 30 to the primer layer 20 can be improved. The amount of resin applied to the primer layer 20 is, for example, 0.01 to 1.5 g / m. 2 and may be 0.05 to 1.0 g / m 2 may be.

[0023] The printed matter 100 has a printing surface 32 on a primer layer 20. An electrostatic ink layer 30 is provided on the printing surface 32. The electrostatic ink layer 30 is composed of halftone dots 31 of an electrostatic ink composition. The electrostatic ink layer 30 is provided by electrostatic printing (digital printing) using a digital printing machine so as to cover a portion of the primer layer 20. Digital printing uses offset printing, which applies ink on a flat surface, so the ink can be applied to the paper substrate 10 with greater uniformity than gravure printing, and the circularity of the ink halftone dots after printing can be increased. As shown in FIG. 1 , the electrostatic ink layer 30 composed of halftone dots 31 may be provided so as to cover a portion of the surface of the primer layer 20. In other words, the halftone dots 31 may be provided scattered on the primer layer 20.

[0024] The electrostatic ink layer 30 may be composed of only a plurality of halftone dots 31 of a single color, or may be composed of a plurality of halftone dots 31 of different colors. In this example, the plurality of halftone dots 31 have the same height, but this is not limited to this. In this example, the electrostatic ink layer 30 is interrupted in the horizontal direction of FIG. 1. The interrupted portions of the electrostatic ink layer 30, i.e., the portions without halftone dots 31, are blank areas. Because the electrostatic ink composition does not contain organic solvents, a printed matter 100 having the electrostatic ink layer 30 can reduce the environmental impact.

[0025] The thickness of the electrostatic ink layer 30 (the height of the halftone dots 31) can be adjusted by changing the ink coverage. Ink coverage represents the ratio of the area of ​​the halftone dots 31 per unit area. For example, when the printing surface 32 is uniformly printed in a single color, the ink coverage is 100%. On the other hand, the ink coverage of an unprinted area (plain area) is 0%. The ink coverage can be calculated based on these two values. For example, applying one coat of ink results in an ink coverage of 200%, and applying two coats of ink results in an ink coverage of 300%. In this way, the ink coverage can be increased by increasing the number of coats. If only half of the entire area of ​​the printing surface 32 is printed once, the ink coverage is 50%. When printing with multiple colors of ink, the ink coverage for each color of electrostatic ink is calculated, and the sum of these values ​​can be used as the ink coverage of the target electrostatic ink layer 30.

[0026] If the ink coverage is high, the halftone dots 31 will connect to each other, making it difficult to calculate the circularity. Therefore, in the printed matter 100, the ink coverage may be less than 100%, 80% or less, or 60% or less. With such ink coverage, the thickness of the electrostatic ink layer 30 can be reduced and the halftone dots 31 can form the electrostatic ink layer 30. Furthermore, the ink coverage may be 5% or more, 10% or more, 20% or more, or 30% or more. With such ink coverage, the circularity of the halftone dots can be sufficiently high. The range of the ink coverage may be, for example, 5% or more but less than 100%, 5 to 80%, 5 to 60%, or 10 to 60%.

[0027] The ink coverage of the present disclosure can be set on a digital press (e.g., HP's Indigo 20000 label and packaging digital press), and therefore the ink coverage can be adjusted to any value using the digital press.

[0028] While the ink coverage is a set value for a digital printing machine, the ink area ratio in this disclosure indicates the area ratio of the ink actually printed on the paper substrate 10. When ink is printed on the primer layer 20, the halftone dots are printed with spreading or missing, resulting in a value that differs from the ink coverage set on the device. However, because the electrostatic ink layer 30 of the printed matter 100 is formed on the paper substrate 10 using digital printing, the difference between the set ink coverage and the actually printed ink area ratio can be reduced. This allows the electrostatic ink layer 30 to be formed on the paper substrate 10 with an ink area ratio close to the set ink coverage. In such a printed matter 100, missing and rubbing of the halftone dots 31 are further reduced, and the electrostatic ink is printed with even higher resolution. This further increases the design freedom of the printed matter 100.

[0029] The absolute value of the difference between the ink coverage rate and the ink area rate of the printed matter 100 may be 7.0% or less. The absolute value of the difference between the ink coverage rate and the ink area rate may also be 6.0% or less, 5.0% or less, or 4.5% or less. By having the printed matter 100 have an area within the above range, the degree of freedom in design can be further improved. The absolute value of the difference between the ink coverage rate and the ink area rate may also be 0.1% or more, 0.5% or more, or 1.0% or more. An example of the absolute value of the difference between the ink coverage rate and the ink area rate may be 0.1 to 7.0%.

[0030] The electrostatic ink composition that makes up the electrostatic ink layer 30 is an ink composition used in liquid electrophotographic printing, i.e., electrostatic printing, and is printed on the primer layer 20. The electrostatic ink composition may contain a colorant or pigment, such as a dye, and a resin. In addition to these, the electrostatic ink composition may also contain a carrier fluid or carrier liquid. It may also contain a charge director, a charge adjuvant, a surfactant, a viscosity modifier, an emulsifier, and other additives.

[0031] Examples of colorants include cyan pigments, magenta pigments, yellow pigments, black pigments, and white pigments. To facilitate digital printing, resins with relatively low melting points (e.g., 100°C or lower) can be used. Examples of resins include thermoplastic resins such as ethylene acrylic acid copolymers, propylene acrylic acid copolymers, ethylene methacrylic acid copolymers, propylene methacrylic acid copolymers, and ethylene vinyl acetate copolymers. The resin preferably contains at least one of ethylene acrylic acid copolymers and ethylene methacrylic acid copolymers.

[0032] Carrier fluids and carrier liquids include hydrocarbons, silicone oils, vegetable oils, and the like. Hydrocarbons include aliphatic hydrocarbons, branched-chain aliphatic hydrocarbons, and aromatic hydrocarbons. The electrostatic ink composition may be substantially free of carrier liquid when printed onto a printing substrate, such as a paper substrate. The carrier liquid may be removed, for example, by an electrophoretic process or evaporation during printing, thereby transferring substantially only solids to the printing substrate.

[0033] Charge directors serve to maintain a sufficient electrostatic charge on particles contained in the electrostatic ink composition, and include ionic compounds such as metal salts of fatty acids, metal salts of sulfosuccinates, metal salts of oxyphosphates, metal salts of alkylbenzene sulfonic acids, and metal salts of aromatic carboxylic or aromatic sulfonic acids, as well as zwitterionic and nonionic compounds such as polyoxyethylenated alkylamines, lecithin, polyvinylpyrrolidone, and organic acid esters of polyhydric alcohols.

[0034] Charge adjuvants have the effect of increasing or stabilizing the charge of particles contained in the electrostatic ink composition. Examples of charge adjuvants include barium petronate, calcium petronate, Co naphthenate, Ca naphthenate, Cu naphthenate, Mn naphthenate, Ni naphthenate, Zn naphthenate, Fe naphthenate, Ba stearate, Co stearate, Pb stearate, Zn stearate, Al stearate, Cu stearate, Fe stearate, and metal carboxylates.

[0035] The electrostatic ink composition may contain a crosslinked product crosslinked by a component contained in the primer layer 20. This makes it possible to sufficiently increase the strength of the electrostatic ink layer 30 itself, as well as the adhesive strength between the printing surface 32 and the electrostatic ink layer 30, and between the electrostatic ink layer 30 and the primer layer 20.

[0036] <Second embodiment of printed matter> Fig. 2 is a cross-sectional view showing an example of a printed matter according to the second embodiment. Fig. 2 shows a cross-section along the layering direction (thickness direction) of printed matter 105. Unlike printed matter 100 (Fig. 1), printed matter 105 has an electrostatic ink layer 30A that is continuous and uninterrupted in the horizontal direction. In this case, multiple halftone dots 31 are connected to each other to form electrostatic ink layer 30A. This allows for greater freedom in designing printed matter.

[0037] In the printed matter 105, the surface smoothness of the paper substrate 10 is 8 seconds or more. When the surface smoothness of the paper substrate 10 of the printed matter 105 is 8 seconds or more, the electrostatic ink layer 30A can be printed with high resolution even when an uneven paper substrate 10 is used, thereby improving design freedom. The surface smoothness of the paper substrate 10 may be 9 seconds or more, or 10 seconds or more. With the surface smoothness in the above range, the electrostatic ink layer 30A can be printed with even higher resolution on a paper substrate 10 with significant unevenness. The surface smoothness of the paper substrate 10 may be 300 seconds or less, or 250 seconds or less. With the surface smoothness in the above range, the electrostatic ink layer 30A can be printed with high resolution even on a paper substrate 10 with significant unevenness that would cause chipping or rubbing of the halftone dots in gravure printing. An example of the range of the surface smoothness of the paper substrate 10 may be 8 to 300 seconds.

[0038] In the printed matter 105, the ink coverage of the electrostatic ink layer 30 may be adjusted to a value that results in island-like halftone dots 31. That is, in the printed matter 105, the ink coverage may be 5% or more but less than 100%, 5 to 80%, 5 to 60%, or 10 to 60%. In this case, the printed matter 105 has the same configuration as the printed matter 100 (FIG. 1). On the other hand, the ink coverage of the printed matter 105 can also be 100% or more. When the ink coverage is 100% or more, the halftone dots 31 in the electrostatic ink layer 30 are connected to each other and printed without gaps on the primer layer 20. This allows for the formation of a solid ink pattern on the paper substrate 10, thereby improving the flexibility of printing on the paper substrate 10. The ink coverage may be 500% or less, 400% or less, 300% or less, or 200% or less. By keeping the ink coverage within the above range, the thickness of the electrostatic ink layer 30 can be reduced. Therefore, an example of the range of ink coverage on the printed matter 105 may be 5 to 500%.

[0039] In the printed matter 105, the descriptions of the paper substrate 10, the primer layer 20, and the electrostatic ink layer 30 can be applied as they are to the descriptions of the printed matter 100. The printed matter 105 and the printed matter 100 may also be combined. This allows for even greater freedom in the design of the printed matter.

[0040] [Laminate] Fig. 3 shows an example of a laminate according to one embodiment. Fig. 3 shows a cross section of a laminate 200 along the lamination direction (thickness direction). The laminate 200 includes a printed matter 100, and includes an adhesive layer S and a sealant layer 40 on the other surface 10B of the paper substrate 10, in this order from the paper substrate 10 side. The structure of the printed matter 100 may be as shown in Fig. 1. Because the laminate 200 includes the printed matter 100, it offers excellent design freedom.

[0041] The adhesive layer S may be a solvent-based or solventless type. The thickness of the adhesive layer S may be 0.5 to 5 μm, 0.6 to 3 μm, or 0.8 to 2 μm. This allows a good balance between adhesive strength and design. The thickness of each layer constituting the laminate 200 can be measured by observing the cross section of the laminate 200 with a digital microscope.

[0042] The adhesive layer S may contain a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof. The adhesive composition may be a two-component curing type. A portion of the polyisocyanate component and the polyol component may react with each other to form a cured product containing polyurethane. The solvent-free nature of the adhesive layer S can further reduce the environmental impact. Furthermore, the absence of an organic solvent prevents penetration of the organic solvent into the paper substrate 10 when dried at low temperatures during adhesion, thereby improving the adhesive strength between the paper substrate 10 and the sealant layer 40.

[0043] The polyisocyanate component may contain a hexamethylene diisocyanate derivative (hereinafter, sometimes referred to as an "HDI derivative"). The HDI derivative may be a bifunctional derivative or a trifunctional derivative of hexamethylene diisocyanate. In such a solvent-free adhesive layer S, a crosslinking reaction progresses within the adhesive layer, thereby improving the strength of the adhesive layer S. This improves the adhesive strength between the paper substrate 10 and the sealant layer 40.

[0044] In the adhesive layer S (adhesive composition), the content of the trifunctional derivative of HDI may be higher than the content of the bifunctional derivative of HDI. This allows a crosslinking reaction to proceed in the adhesive layer S, improving the strength of the adhesive layer S and enabling the adhesive strength between the paper substrate 10 and the sealant layer 40 via the adhesive layer S to be sufficiently increased. From this perspective, the mass ratio of the trifunctional derivative to the total of the bifunctional derivative and the trifunctional derivative may be 55 mass% or more, or may be 60 mass% or more. On the other hand, from the perspective of maintaining the flexibility of the adhesive layer S, the mass ratio of the trifunctional derivative to the total of the bifunctional derivative and the trifunctional derivative may be 85 mass% or less, 80 mass% or less, or 75 mass% or less. An example of the mass ratio of the trifunctional derivative to the total of the bifunctional derivative and the trifunctional derivative is 55 to 85 mass%.

[0045] Examples of HDI derivatives include HDI multimers (e.g., dimers, trimers, pentamers, heptamers, etc.), biuret-modified products (e.g., biuret-modified products produced by the reaction of HDI with water, tertiary alcohols, or amines), allophanate-modified products (e.g., allophanate-modified products produced by the reaction of HDI with alcohols), urea-modified products (e.g., urea-modified products produced by the reaction of HDI with diamines), oxadiazinetrione (e.g., oxadiazinetrione produced by the reaction of HDI with carbon dioxide), carbodiimide-modified products (e.g., carbodiimide-modified products produced by the decarboxylation condensation reaction of HDI), and polyol-modified products. HDI may also be an adduct of HDI with trimethylolpropane.

[0046] The content of the HDI derivative in the polyisocyanate component may be 15% by mass or more, 20% by mass or more, or 25% by mass or more. This allows the above-mentioned effects to be fully exhibited. The content of the HDI derivative in the polyisocyanate component may be 60% by mass or less, 50% by mass or less, or 40% by mass or less. An example of the content of the HDI derivative in the polyisocyanate component is 15 to 60% by mass.

[0047] The polyisocyanate component may further contain a polyisocyanate having two or more isocyanate groups in one molecule, which is different from the HDI derivative. This allows for flexibility in designing the laminate 200 according to the desired properties. Examples of such polyisocyanate monomers include aromatic diisocyanates, aromatic alicyclic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates.

[0048] Aromatic diisocyanates are highly reactive and easily cured, allowing for rapid production of the laminate 200. Examples of aromatic aliphatic diisocyanates include m- or p-phenylene diisocyanate or a mixture thereof, 2,4- or 2,6-tolylene diisocyanate or a mixture thereof (TDI), 4,4'-, 2,4'-, or 2,2'-diphenylmethane diisocyanate or a mixture thereof (MDI), 4,4'-toluidine diisocyanate (TODI), 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, and 1,5-naphthalene diisocyanate (NDI).

[0049] Examples of the aromatic aliphatic diisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof (XDI), 1,3- or 1,4-tetramethylxylylene diisocyanate or a mixture thereof (TMXDI), and ω,ω'-diisocyanato-1,4-diethylbenzene.

[0050] Examples of the aliphatic diisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 1,2-, 2,3- or 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and the like.

[0051] Examples of alicyclic diisocyanates include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate; IPDI), 4,4'-, 2,4'-, or 2,2'-dicyclohexylmethane diisocyanate or mixtures thereof (hydrogenated MDI), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane or mixtures thereof (hydrogenated XDI), and the like.

[0052] The polyisocyanate component may contain a derivative of the polyisocyanate monomer (polyisocyanate derivative). Examples of the polyisocyanate derivative include (for example, a dimer, trimer, pentamer, heptamer, etc.), allophanate-modified products (for example, an allophanate-modified product produced by reacting a polyisocyanate monomer with an alcohol), biuret-modified products (for example, a biuret-modified product produced by reacting a polyisocyanate monomer with water or an amine), urea-modified products (for example, a urea-modified product produced by reacting a polyisocyanate monomer with a diamine), oxadiazinetrione (for example, oxadiazinetrione produced by reacting a polyisocyanate monomer with carbon dioxide), and carbodiimide-modified products (for example, a carbodiimide-modified product produced by a decarboxylation condensation reaction of a polyisocyanate monomer).

[0053] The polyisocyanate component may include an isocyanate-terminated prepolymer. The isocyanate-terminated prepolymer is a urethane prepolymer having at least two isocyanate groups at the molecular end. The urethane prepolymer can be obtained by a urethane reaction between at least one member selected from the group consisting of a polyisocyanate monomer, a polyisocyanate derivative, and an isocyanate-terminated prepolymer and a polyol.

[0054] The polyol component may contain at least one selected from the group consisting of polyester polyols and polyether polyols. Among these, polyether polyols may be included from the viewpoints of reducing production costs and suppressing hydrolysis.

[0055] The polyether polyol may be a polyalkylene oxide. For example, it may be obtained by addition reaction of an alkylene oxide such as ethylene oxide and / or propylene oxide with a low molecular weight polyol as an initiator. Specific examples include polyethylene glycol, polypropylene glycol, and polyethylene polypropylene glycol (random or block copolymer). Other examples include polytetramethylene ether glycol obtained by ring-opening polymerization of tetrahydrofuran.

[0056] The polyester polyol can be obtained, for example, by a condensation reaction or transesterification reaction between a polyhydric alcohol and a polybasic acid, its alkyl ester, its acid anhydride, or its acid halide. Examples of the polyhydric alcohol include low-molecular-weight diols, low-molecular-weight triols, and low-molecular-weight polyols having four or more hydroxyl groups.

[0057] Examples of low molecular weight diols include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, neopentyl glycol, 1,6-hexanediol, 2,2-diethyl-1,3-propanediol, 3,3-dimethylolheptane, and 2-ethyl-2-butyl-1,3-propanediol.

[0058] Examples of low molecular weight triols include glycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, trimethylolethane, trimethylolpropane, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-(hydroxymethyl)pentane, and 2,2-bis(hydroxymethyl)-3-butanol.

[0059] Examples of low molecular weight polyols having four or more hydroxyl groups include tetramethylolmethane, pentaerythritol, dipentaerythritol, D-sorbitol, xylitol, D-mannitol, and D-mannite.

[0060] Examples of alkyl esters of polybasic acids include methyl esters and ethyl esters of polybasic acids. Examples of acid anhydrides include acid anhydrides derived from polybasic acids, such as oxalic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, 2-alkyl (C12 to C18) succinic anhydride, tetrahydrophthalic anhydride, and trimellitic anhydride.

[0061] The acid halides include those derived from the above-mentioned polybasic acids, such as oxalic acid dichloride, adipic acid dichloride, and sebacic acid dichloride.

[0062] In the adhesive layer S (adhesive composition), the mass ratio of the polyisocyanate component may be higher than the mass ratio of the polyol component. Specifically, the mass ratio of the polyisocyanate component to the polyol component may be 1 or more, 1.2 or more, or even 1.4 or more. In this way, by increasing the mass ratio of the polyisocyanate component to the polyol component, the curing reaction is promoted and the adhesion and curing steps can be sufficiently shortened. From the same viewpoint, the mass ratio of the polyisocyanate component to the polyol component may be 4 or less, or even 3 or less. An example of the mass ratio of the polyisocyanate component to the polyol component is 1 to 4.

[0063] The adhesive composition constituting the adhesive layer S may contain optional components such as additives in addition to the polyisocyanate component and polyol component. Examples of additives include antioxidants, UV absorbers, light stabilizers, fillers, silane coupling agents, epoxy resins, catalysts, coatability improvers, leveling agents, nucleating agents, lubricants, release agents, antifoaming agents, plasticizers, surfactants, pigments, dyes, organic fine particles, inorganic fine particles, antifungal agents, and flame retardants. The adhesive composition is solventless and does not contain solvents such as organic solvents. This reduces the environmental impact and significantly improves the working environment. Solventless adhesive compositions are heated during application.

[0064] Examples of the sealant layer 40 include a non-oriented polypropylene film (CPP film), a linear low-density polyethylene film (LLDPE film), and a low-density polyethylene film (LDPE film). The thickness of the sealant layer 40 may be 10 to 150 μm, 20 to 100 μm, or 30 to 80 μm. The sealant layer 40 may also be a coating layer of a thermoplastic resin, which will be described later, or an extrusion laminate layer.

[0065] The sealant layer 40 may be a non-stretched film. Examples of non-stretched films include CPP film. Non-stretched films shrink when heated, so they need to be heated at low temperatures during bonding. If the adhesive contains an organic solvent, the organic solvent is not sufficiently removed by heating at low temperatures, and the remaining organic solvent penetrates into the paper substrate 10 during bonding, reducing adhesiveness. Therefore, using a solvent-free adhesive can improve the adhesive strength between the non-stretched film and the paper substrate 10. This allows the non-stretched film to be directly bonded to the paper substrate 10, reducing the thickness of the laminate and improving flexibility.

[0066] The adhesive strength between the non-stretched film and the paper substrate 10 can be measured in accordance with the description in JIS K 6854-1:1999 "Adhesives - Test method for peel adhesion strength - Part 1: 90-degree peel." The adhesive strength between the non-stretched film and the paper substrate 10 may be 0.7 (N / 15 mm) or more, 1.0 (N / 15 mm) or more, or 1.3 (N / 15 mm) or more. By ensuring that the adhesive strength is within the above range, the strength of the laminate 200 can be sufficiently high. The adhesive strength between the non-stretched film and the paper substrate 10 may be 2.5 (N / 15 mm) or less. An example of the range of the adhesive strength between the non-stretched film and the paper substrate 10 may be 0.7 to 2.5 (N / 15 mm).

[0067] The laminate 200 may include an anchor coat layer instead of the adhesive layer S. By including an anchor coat layer, the adhesion between the paper substrate 10 and the sealant layer 40 can be improved. The anchor coat layer can be formed by applying an anchor coat agent onto a predetermined layer and drying it. For example, polyester-based polyurethane resin and polyether-based polyurethane resin can be used as the anchor coat agent. The thickness of the anchor coat layer is not particularly limited and may be 0.1 to 1 μm or 0.3 to 0.5 μm. When an anchor coat layer is provided instead of the adhesive layer S, the sealant layer 40 may be an extrusion laminate layer formed by extrusion lamination.

[0068] Fig. 4 is a cross-sectional view showing an example of a laminate according to another embodiment. Fig. 4 shows a cross-section along the lamination direction (thickness direction) of a laminate 202. The laminate 202 includes a printed matter 100, and includes, on the other surface 10B of the paper substrate 10, a first adhesive layer S1, an intermediate layer 50, a second adhesive layer S2, and a sealant layer 40, in this order from the paper substrate 10 side.

[0069] The intermediate layer 50 may include a flexible substrate. The flexible substrate may include, for example, one or both of a thermoplastic polymer film. Flexible substrates include biaxially oriented polypropylene (OPP), biaxially oriented polypropylene (BOPP), polyethylene terephthalate (PET), oriented polyamide (OPA), solid polypropylene (CPP), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and nylon film.

[0070] The intermediate layer 50 may have a metal layer. Examples of the metal layer include aluminum foil. When the intermediate layer 50 contains aluminum foil, the barrier properties of the laminate 202 can be improved. Furthermore, when the solventless adhesive composition contains a surface modifier, the adhesion between the first adhesive layer S1 and the second adhesive layer S2 and the metal layer can be further improved. The thickness of the metal layer may be 1 to 20 μm, 3 to 15 μm, or 5 to 10 μm.

[0071] The metal layer in the intermediate layer 50 may be a vapor-deposited layer. In this case, the intermediate layer 50 may have, for example, a vapor-deposited film (transparent vapor-deposited film) including a resin layer such as a PET film and a barrier layer (vapor-deposited layer) on the resin layer. This can improve the sealing performance when the laminate 202 is used as a packaging material. Examples of the barrier layer include a vapor-deposited layer of a metal oxide (e.g., silica or alumina). Specific examples of vapor-deposited films include an aluminum-deposited PET film in which an aluminum-deposited layer is formed on a PET film, and a transparent vapor-deposited PET film in which a transparent vapor-deposited layer is formed on a PET film. The intermediate layer 50 may include a nylon film such as a barrier nylon film.

[0072] The first adhesive layer S1 and the second adhesive layer S2 may have the same components and thickness as the adhesive layer S in Fig. 3. The first adhesive layer S1 and the second adhesive layer S2 may contain the same components or different components. The material and thickness of the sealant layer 40 may be as described for the sealant layer 40 in the laminate 200 in Fig. 3.

[0073] The first adhesive layer S1 and / or the second adhesive layer S2 (adhesive composition) may contain a surface modifier that improves adhesion to the paper substrate 10, the intermediate layer 50, and the sealant layer 40. When the intermediate layer 50 is a barrier layer made of metal or the like, the adhesive strength and sealing strength between the first adhesive layer S1 and / or the second adhesive layer S2 and the barrier layer can be further increased. When the barrier layer has a metal layer (aluminum layer) such as a metal foil (aluminum foil) or a metal film (aluminum film), the first adhesive layer S1 and / or the second adhesive layer S2 (adhesive composition) can contain a surface modifier to further improve adhesion to the metal layer. This further increases the adhesive strength of the adhesive layer, resulting in a laminate 202 with even better tearability.

[0074] Examples of the surface modifier include those containing at least one selected from sulfamic acid, phosphoric acid, nitric acid, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, and ethyl hydroxyethyl cellulose.

[0075] Fig. 5 is a cross-sectional view showing an example of a laminate according to yet another embodiment. Fig. 5 shows a cross section along the lamination direction (thickness direction) of a laminate 204. The laminate 204 includes a printed matter 100 and a thermoplastic resin coating layer 60 on the other side 10B of the paper substrate 10.

[0076] The coating layer 60 is a thermoplastic resin. The coating layer 60 may contain at least one of polypropylene (PP), polyethylene terephthalate (PET), polyethylene (PE), low melting point polyethylene, cross-linked polyethylene, low density polyethylene (LDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMAA), ionomer, etc. The coating layer 60 can be formed by applying a thermoplastic resin to the paper substrate 10.

[0077] The coating layer 60 in the laminate 204 is made of a thermoplastic resin, and therefore has the same function as the sealant layer 40 in Figures 3 and 4, and can form a seal when producing a packaging bag. Since such a laminate 204 does not have an adhesive layer, the thickness of the laminate 204 can be made thin.

[0078] The laminates 200, 202, 204 of the present disclosure are not limited to the laminate structure shown in FIG. 3, FIG. 4, or FIG. 5. For example, modified versions of the laminates 200, 202, 204 may include a printed material 105 instead of the printed material 100. The structure of the printed material 105 in the modified version may be as described in FIG. 2. Furthermore, for example, modified versions of the laminates 200, 202, 204 may have the following laminate structures. In each example, the leftmost layer is the electrostatic ink layer 30, 30A, and the rightmost layer is the sealant layer 40 or coating layer 60. In each example, the layers are arranged in order from left to right. Note that the laminate structure of the laminate is not limited to the following examples.

[0079] Example 1) Electrostatic ink layer / primer layer / paper substrate / adhesive layer / LLDPE film (linear low-density polyethylene film) Example 2) Electrostatic ink layer / primer layer / paper substrate / adhesive layer / LDPE film Example 3) Electrostatic ink layer / primer layer / paper substrate / adhesive layer / CPP film (non-oriented polypropylene film) Example 4) Electrostatic ink layer / primer layer / paper substrate / first adhesive layer / LLDPE film / second adhesive layer / LLDPE film Example 5) Electrostatic ink layer / primer layer / paper substrate / first adhesive layer / CPP film / second adhesive layer / LLDPE film Example 6) Electrostatic ink layer / primer layer / paper substrate / first adhesive layer / LLDPE film / second adhesive layer / CPP film Example 7) Electrostatic ink layer / primer layer / paper substrate / first adhesive layer / metal layer / second adhesive layer / CPP film Example 8) Electrostatic ink layer / primer layer / paper substrate / first adhesive layer / deposited film / second adhesive layer / CPP film Example 9) Electrostatic ink layer / primer layer / paper substrate / first adhesive layer / transparent vapor deposition film / second adhesive layer / CPP film Example 10) Electrostatic ink layer / primer layer / paper substrate / first adhesive layer / transparent vapor deposition film / second adhesive layer / CPP film Example 11) Electrostatic ink layer / primer layer / paper substrate / anchor coat layer / extrusion sealant layer Example 12) Electrostatic ink layer / primer layer / paper substrate / adhesive layer / deposited film / anchor coat layer / extrusion sealant layer Example 13) Electrostatic ink layer / primer layer / paper substrate / adhesive layer / metal layer / anchor coat layer / extrusion sealant layer Example 14) Electrostatic ink layer / primer layer / paper substrate / adhesive layer / CPP film / anchor coat layer / extrusion sealant layer Example 15) Electrostatic ink layer / primer layer / paper substrate / anchor coat layer / extruded resin layer / extruded sealant layer Example 16) Electrostatic ink layer / primer layer / paper substrate / coating layer (PP) Example 17) Electrostatic ink layer / primer layer / paper substrate / coating layer (PE) Example 18) Electrostatic ink layer / primer layer / paper substrate / coating layer (EMAA)

[0080] [Packaging bag] FIG. 6 is a plan view showing an example of a packaging bag formed using the above-described laminate. The packaging bag 150 is formed by bonding the sealant layers 40 of a pair of laminates 200 together. The surface on the electrostatic ink layer 30 side becomes the outer surface of the packaging bag 150. The packaging bag 150 includes a sealed portion 101 formed by bonding the peripheral edges of a pair of approximately rectangular laminates 200 together, and a storage portion 102 formed between the pair of laminates 200 by the sealed portion 101. That is, the side edges, bottom edge, and top edge of the packaging bag 150 are sealed by the sealed portion 101. The packaging bag 150 includes the storage portion 102 in which the packaged item (e.g., food) is stored in a non-sealed portion (sheet portion) surrounded by the sealed portion 101. The sealed portion 101 at the bottom edge may be sealed after the packaged item is filled in the storage portion 102. The sealed portion 101 is formed by heat-sealing the sealant layers 40 together.

[0081] The packaging bag 150 may be configured by bonding together the sealant layers 40 of the laminate 202 instead of the laminate 200 to form the sealed portion 101. Alternatively, the packaging bag 150 may be configured by bonding together the coating layers 60 of the laminate 204 instead of the laminate 200 to form the sealed portion 101.

[0082] It is not essential that the pair of packaging materials that make up the packaging bag 150 have the same layer structure, and for example, the pair of packaging materials may be made up of laminates having different layer structures.

[0083] The packaging bag 150 may be provided with opening means 120 for making it easier to open. The opening means has a pair of easy-open processed portions 124 consisting of V-shaped notches formed in the sealed portion 101 at the side edge, and a half-cut line 121 between the pair of easy-open processed portions 124 that serves as a cutting path. The half-cut line 121 can be formed using a laser. The easy-open processed portions 124 are not limited to V-shaped notches, and may be U-shaped or I-shaped notches, or may be a group of scars.

[0084] The packaging bag 150 includes the laminate 200 (202, 204), and is printed with high resolution even when a paper substrate is used, allowing for excellent design freedom. Such a packaging bag 150 can be suitably used as a package. Furthermore, because the packaging bag 150 uses the laminate 200 (202, 204) that uses a paper substrate, the environmental impact can be reduced.

[0085] A package may be produced by providing a packaging bag 150 and an item to be contained in the container 102 of the packaging bag 150. The item to be contained is not particularly limited and may be a solid, a liquid, or a mixture thereof. Examples include food, beverages, medicines, electronic devices, etc. Because the package includes the packaging bag 150 with the laminate 200 (202, 204), even if a paper substrate is used, it is printed with high resolution, allowing for excellent design freedom. Furthermore, because the package uses the laminate 200 (202, 204) with a paper substrate, the environmental impact can be reduced.

[0086] The procedure for manufacturing a packaging bag 150 using the laminate 200 (202, 204) is described below. A pair of laminates 200 (202, 204) cut to a predetermined shape is prepared as packaging materials. The sealant layers 40 or coating layers 60 provided on one side of each laminate 200 (202, 204) are placed opposite each other, and the sealant layers 40 or coating layers 60 are bonded to each other. This forms sealed portions 101 at the upper and side edges, forming an unsealed portion surrounded by the sealed portions 101 in a U-shape. In this manner, a packaging bag 155 is obtained in which only the upper end (or only the lower end) is unsealed, as shown in FIG. 7. After sealing the unsealed portion at the upper end (or lower end) of the packaging bag 155, the opening means 120 is formed to obtain the packaging bag 150. In some examples, the packaging bag of this embodiment may have a portion of its periphery unsealed, as shown in FIG. 7.

[0087] When producing a package, the contents to be packaged are filled into the packaging bag 155 from the unsealed upper end (or lower end). Thereafter, the stacks 200 (202, 204) are bonded together at the upper end (or lower end), and a seal portion 101 is also formed at the upper end (or lower end). In this way, a package including the packaging bag 150 and the contents contained therein can be produced.

[0088] The packaging bag 150 and the packaging body are manufactured using the laminate 200 (202, 204). Therefore, the environmental impact is reduced by using a paper base material, and various patterns can be printed, which increases consumer purchasing motivation.

[0089] Although several examples have been described above, this embodiment is not limited to the above examples. The shape of the packaging bag may be, for example, a four-sided bag, a zipper bag, a standing bag, a gusset bag, a two-sided bag, a three-sided bag, a folded bag, or the like.

[0090] The present disclosure includes the following embodiments and modifications thereof. [1] A paper substrate, a primer layer on one side of the paper substrate, and an electrostatic ink layer covering at least a portion of the primer layer, A printed matter, wherein the circularity of the halftone dots constituting the electrostatic ink layer is 0.6 or more. [2] The printed matter described in [1], wherein the surface smoothness of the paper substrate is 8 seconds or more. [3] A paper substrate, a primer layer on one side thereof, and an electrostatic ink layer covering at least a portion of the primer layer, A printed matter in which the surface smoothness of the paper substrate is 8 seconds or more. [4] The printed matter according to any one of [1] to [3], wherein the surface smoothness of the paper substrate is 300 seconds or less. [5] The basis weight of the paper base material is 100 g / m 2 A printed matter according to any one of [1] to [4] below. [6] The printed matter according to any one of [1] to [5], wherein the absolute value of the difference between the ink coverage rate of the electrostatic ink layer and the ink area rate is 7.0% or less. [7] A laminate comprising the printed matter according to any one of [1] to [6] above, and comprising an adhesive layer and a sealant layer in this order from the paper substrate side on the other side of the paper substrate. [8] A laminate comprising the printed matter according to any one of [1] to [6] above, and a coating layer of a thermoplastic resin on the other side of the paper base material. [9] The laminate according to [7], wherein the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof.

[10] The laminate according to [7] or [9], wherein the sealant layer is a non-stretched film.

[11] A packaging bag constructed by heat-sealing the sealant layers of the laminate according to any one of [7] or [9] to

[10] above.

[12] A packaging bag formed by heat-sealing the coating layers of the laminate described in [8] above. [Example]

[0091] The present invention will be described in more detail with reference to Examples, Comparative Examples and Reference Examples, but the present invention is not limited to the following Examples.

[0092] (Reference example 1) The paper substrate was a commercially available single-sided art paper (product name: G Art, manufactured by Oji Paper Co., Ltd., basis weight: 79.1 g / m) with a coating on one side. 2 ) was prepared. The surface smoothness of the coated surface was measured in accordance with JIS P8155:2010 "Paper and paperboard - Smoothness test method - Oken method" and was found to be 610 seconds. Ink was printed on the coated surface by gravure printing. The ink coverage was set to 10%.

[0093] The ink-printed surface was then observed at 200x magnification using an optical microscope and photographed. The photographs are shown in Figure 8. The circularity of the dots in Figure 8 was calculated using the following formula (1). Specifically, the average dot area was calculated by averaging the area of ​​all dots included in the photograph in Figure 8 using image analysis. Similarly, the average dot perimeter was calculated by averaging the perimeter of all dots included in the photograph in Figure 8 using image analysis. Note that dots that were not visible in the photograph in Figure 8 were excluded from the calculation. The calculated average dot area and average dot perimeter were substituted into formula (1) to calculate the circularity of the dots. As a result, the circularity of the dots was calculated to be 0.91. (Circularity of halftone dots) = 4π × (average area of ​​halftone dots) / (average perimeter of halftone dots) 2 (1)

[0094] (Reference example 2) The paper substrate was a commercially available pure white roll paper (product name: Kinshachi, manufactured by Nagoya Pulp Co., Ltd., basis weight: 50.0 g / m 2 Gravure printing was performed in the same manner as in Reference Example 1, except that the printing time was set to 10 seconds (surface smoothness: 10 seconds). A photograph of the printed surface taken with an optical microscope at 200x magnification is shown in Figure 9. The circularity of the dots calculated in the same manner as in Reference Example 1 was 0.77.

[0095] (Reference example 3) The paper substrate was a commercially available high-quality paper (product name: OFD-2 COC, manufactured by Oji F-Tex Co., Ltd., basis weight: 52.3 g / m 2 Gravure printing was performed in the same manner as in Reference Example 1, except that the printing time was set to 10 seconds (100 seconds, surface smoothness: 50 seconds). A photograph of the printed surface taken with an optical microscope at 200x magnification is shown in Figure 10. The circularity of the dots calculated in the same manner as in Reference Example 1 was 0.73.

[0096] (Reference example 4) Gravure printing was performed using the same procedure as in Reference Example 1, except that the paper substrate was changed to a commercially available PET film. A photograph of the printed surface taken using an optical microscope at 200x magnification is shown in Figure 11. The circularity of the dots calculated using the same procedure as in Reference Example 1 was 0.91.

[0097] 8 to 11, when gravure printing was used, Reference Example 1, which used a paper substrate with high surface smoothness, had dot circularity equivalent to that of Reference Example 4, which used a PET film. On the other hand, Reference Examples 2 and 3, which used paper substrates with low surface smoothness, had dot circularity lower than Reference Examples 1 and 4. Therefore, it was confirmed that when the surface smoothness of the paper substrate is low, that is, when the surface of the paper substrate is highly uneven, chipping and rubbing of the printed dots are more likely to occur, and as a result, the dot circularity tends to be lower.

[0098] Example 1 [Printing] The paper substrate was a commercially available pure white roll paper (product name: Kinshachi, manufactured by Nagoya Pulp Co., Ltd., basis weight: 50.0 g / m 2 , surface smoothness: 10 seconds). An aqueous primer resin (a resin containing polyethyleneimine, manufactured by Michelman, product name: DP050) was applied to one side of the paper substrate to form a primer layer. At this time, the amount of aqueous polyethyleneimine applied was 0.10 to 0.18 g / m 2 The water-based primer resin was applied to the surface of the paper substrate so that the surface roughness was 100%.

[0099] An electrostatic ink composition was applied to the surface of the primer layer using a digital printing machine (HP Indigo 20000 label and packaging digital printing machine) to form an electrostatic ink layer, resulting in a printed product. Digital printing was performed with the digital printing machine set to an ink coverage of 5%. The electrostatic ink composition used was an electrostatic ink composition (HP Indigo Electroink) containing a thermoplastic resin containing a copolymer of ethylene acrylic acid and ethylene methacrylic acid.

[0100] The printed surface of the obtained print was observed using an optical microscope at a magnification of 100 times and photographed. The photograph is shown in Figure 12(a).

[0101] (Comparative Example 1) Commercially available pure white roll paper (product name: Kinshachi, manufactured by Nagoya Pulp Co., Ltd., basis weight: 50.0 g / m2 Ink was printed onto the substrate (surface smoothness: 10 seconds) using gravure printing at an ink coverage of 5%. The printed surface was observed and photographed using an optical microscope at 100x magnification. The photograph is shown in Figure 12(b).

[0102] Example 2 A printed matter was produced in the same manner as in Example 1, except that the ink coverage was set to 10%. The printed surface of the obtained printed matter was observed using an optical microscope at 100x magnification and photographed. The photograph is shown in Figure 13(a).

[0103] (Comparative Example 2) A printed matter was produced in the same manner as in Comparative Example 1, except that the ink coverage was set to 10%. The printed surface of the obtained printed matter was observed at 100x magnification using an optical microscope and photographed. The photograph is shown in Figure 13(b).

[0104] Example 3 A printed matter was produced in the same manner as in Example 1, except that the ink coverage was set to 20%. The printed surface of the obtained printed matter was observed at 100x magnification using an optical microscope and photographed. The photograph is shown in Figure 14(a).

[0105] (Comparative Example 3) A printed matter was produced in the same manner as in Comparative Example 1, except that the ink coverage was set to 20%. The printed surface of the obtained printed matter was observed at 100x magnification using an optical microscope and photographed. The photograph is shown in Figure 14(b).

[0106] Example 4 A printed matter was produced in the same manner as in Example 1, except that the ink coverage was set to 30%. The printed surface of the obtained printed matter was observed at 100x magnification using an optical microscope and photographed. The photograph is shown in Figure 15(a).

[0107] Comparative Example 4 A printed matter was produced in the same manner as in Comparative Example 1, except that the ink coverage was set to 30%. The printed surface of the obtained printed matter was observed at 100x magnification using an optical microscope and photographed. The photograph is shown in Figure 15(b).

[0108] Example 5 A printed matter was produced in the same manner as in Example 1, except that the ink coverage was set to 40%. The printed surface of the obtained printed matter was observed using an optical microscope at 100x magnification and photographed. The photograph is shown in Figure 16(a).

[0109] (Comparative Example 5) A printed matter was produced in the same manner as in Comparative Example 1, except that the ink coverage was set to 40%. The printed surface of the obtained printed matter was observed at 100x magnification using an optical microscope and photographed. The photograph is shown in Figure 16(b).

[0110] Example 6 A printed matter was produced in the same manner as in Example 1, except that the ink coverage was set to 50%. The printed surface of the obtained printed matter was observed using an optical microscope at a magnification of 100x and photographed. The photograph is shown in Figure 17(a).

[0111] (Comparative Example 6) A printed matter was produced in the same manner as in Comparative Example 1, except that the ink coverage was set to 50%. The printed surface of the obtained printed matter was observed at 100x magnification using an optical microscope and photographed. The photograph is shown in Figure 17(b).

[0112] Example 7 A printed matter was produced in the same manner as in Example 1, except that the ink coverage was set to 60%. The printed surface of the obtained printed matter was observed using an optical microscope at 100x magnification and photographed. The photograph is shown in Figure 18(a).

[0113] (Comparative Example 7) A printed matter was produced in the same manner as in Comparative Example 1, except that the ink coverage was set to 60%. The printed surface of the obtained printed matter was observed at 100x magnification using an optical microscope and photographed. The photograph is shown in Figure 18(b).

[0114] Example 8 A printed matter was produced in the same manner as in Example 1, except that the ink coverage was set to 70%. The printed surface of the obtained printed matter was observed at 100x magnification using an optical microscope and photographed. The photograph is shown in Figure 19(a).

[0115] (Comparative Example 8) A printed matter was produced in the same manner as in Comparative Example 1, except that the ink coverage was set to 70%. The printed surface of the obtained printed matter was observed at 100x magnification using an optical microscope and photographed. The photograph is shown in Figure 19(b).

[0116] Example 9 A printed matter was produced in the same manner as in Example 1, except that the ink coverage was set to 80%. The printed surface of the obtained printed matter was observed using an optical microscope at 100x magnification and photographed. The photograph is shown in Figure 20(a).

[0117] Comparative Example 9 A printed matter was produced in the same manner as in Comparative Example 1, except that the ink coverage was set to 80%. The printed surface of the obtained printed matter was observed using an optical microscope at 100x magnification and photographed. The photograph is shown in Figure 20(b).

[0118] Example 10 A printed matter was produced in the same manner as in Example 1, except that the ink coverage was set to 90%. The printed surface of the obtained printed matter was observed using an optical microscope at 100x magnification and photographed. The photograph is shown in Figure 21(a).

[0119] (Comparative Example 10) A printed matter was produced in the same manner as in Comparative Example 1, except that the ink coverage was set to 90%. The printed surface of the obtained printed matter was observed at 100x magnification using an optical microscope and photographed. The photograph is shown in Figure 21(b).

[0120] Example 11 A printed matter was produced in the same manner as in Example 1, except that the ink coverage was set to 100%. The printed surface of the obtained printed matter was observed at 100x magnification using an optical microscope and photographed. The photograph is shown in Figure 22(a).

[0121] (Comparative Example 11) A printed matter was produced in the same manner as in Comparative Example 1, except that the ink coverage was set to 100%. The printed surface of the obtained printed matter was observed using an optical microscope at 100x magnification and photographed. The photograph is shown in Figure 22(b).

[0122] As shown in Figure 18(b), in gravure printing, at an ink coverage of 60%, the halftone dots were connected and the plain areas were almost completely eliminated. Furthermore, as shown in Figures 19(b), 20(b), 21(b), and 22(b), at ink coverages of 70% or more, the plain areas were almost completely eliminated in gravure printing. On the other hand, in digital printing, as shown in Figure 18(a), halftone dots could be observed even at an ink coverage of 60%. Furthermore, in digital printing, as shown in Figures 19(a), 20(a), and 21(a), the halftone dots gradually began to connect at ink coverages of 70% or more. Furthermore, as shown in Figure 22(a), it was confirmed that the plain areas completely disappeared at an ink coverage of 100% (Example 11). These results demonstrate that digital printing can print at higher resolution on paper substrates than gravure printing.

[0123] As shown in Figures 12 to 22 (a) and (b), when comparing the printed surface of a paper substrate when digitally printed with that when gravure printed, clearer halftone dots were observed with digital printing, confirming that high-resolution printing is possible. Because the surface of a paper substrate is uneven, gravure printing does not allow the ink to be applied to the surface with high uniformity, making it prone to chipping and rubbing of the halftone dots. On the other hand, digital printing uses offset printing, which prints flat on the paper substrate, so the ink can be applied with high uniformity even if the paper substrate is uneven. Therefore, digital printing reduces chipping and rubbing of the halftone dots, allowing for beautiful halftone dots to be printed on the paper substrate.

[0124] <Evaluation of circularity of halftone dots> The circularity of the halftone dots was evaluated in Examples 4, 5, and 6 and Comparative Examples 4, 5, and 6. The halftone dots were calculated using the following formula (1) based on a photograph of the printed surface on which the ink was printed. The calculation of the circularity of the halftone dots in Example 4 will be explained below. The average value of the area of ​​all halftone dots included in the photograph of FIG. 15(a) was obtained by image analysis. Similarly, the average value of the perimeter of the halftone dots included in the photograph of FIG. 15(a) was obtained by image analysis. Note that halftone dots that were cut off in the photograph of FIG. 15(a) were excluded. The calculated average value of the halftone dot area and the average value of the halftone dot perimeter were substituted into the following formula (1) to calculate the circularity of the halftone dots. (Circularity of halftone dots) = 4π × (average area of ​​halftone dots) / (average perimeter of halftone dots) 2 (1)

[0125] In Examples 5 and 6 and Comparative Examples 4, 5, and 6, the circularity of the halftone dots was calculated based on the photograph of each printed surface and formula (1) in the same manner as in Example 4. The results are shown in Table 1.

[0126] <Evaluation of the difference between ink coverage and ink area ratio> In Examples 4, 5, and 6 and Comparative Examples 4, 5, and 6, the difference between the ink coverage rate and the ink area rate was evaluated. The total area of ​​the dots in the observation range of the printed surface was calculated by image analysis, and divided by the observation area to calculate the ink area rate. The absolute value of the difference between the calculated ink area rate and the ink coverage rate was found. The observation area was 8.744 mm 2 The results are shown in Table 1.

[0127] [Table 1]

[0128] When comparing digital printing and gravure printing as printing methods for printing ink on a paper substrate, digital printing resulted in a greater circularity of the halftone dots on the printed surface than gravure printing. Furthermore, in Examples 4, 5, and 6, the circularity of the halftone dots was 0.60 or higher. It was confirmed by visual inspection that the greater the circularity of the halftone dots, the higher the resolution of the printed dots. Thus, it was demonstrated that digital printing reduces dot chipping and rubbing and enables high-resolution printing of halftone dots on a paper substrate. Furthermore, in Examples 4, 5, and 6, the absolute value of the difference between the set ink coverage and the ink area coverage was smaller than in Comparative Examples 4, 5, and 6. Furthermore, since the surface smoothness of the paper substrate used was 10 seconds, it was demonstrated that digital printing can be used to print on paper substrates with relatively rough surfaces.

[0129] (Reference example 5) [Laminate fabrication] As the paper substrate, commercially available pure white roll paper (product name: Kinshachi, manufactured by Nagoya Pulp Co., Ltd., basis weight: 50.0 g / m 2(10 seconds, surface smoothness: 10 seconds) and an unstretched polypropylene film (CPP film, thickness: 30 μm) were prepared as a sealant layer. A solventless adhesive composition was prepared by blending a polyether polyol (manufactured by Toyo-Morton Co., Ltd., product name: EA-N373B, hereinafter also referred to as "(A)") as the base agent and an aromatic polyisocyanate (manufactured by Toyo-Morton Co., Ltd., product name: EA-N373A, hereinafter also referred to as "(B)") as the curing agent. The blending ratio (by mass) of the components was (A):(B) = 50:100.

[0130] The adhesive composition was applied to the sealant layer at a rate of approximately 3.4 g / m 2 The coated film was then placed face-to-face on a paper substrate, and the paper substrate and the sealant layer were bonded together via the coated film (adhesive composition) using a nip roll. The adhesive composition was then cured by aging at 45°C for 2 days. This method yielded a laminate having a paper substrate, an adhesive layer, and a sealant layer in this order.

[0131] [Adhesion strength measurement] The adhesive strength of the prepared laminate was measured in accordance with JIS K 6854-1:1999. Specifically, the prepared laminate was cut into a 15 mm width to obtain a measurement sample. After peeling between the base film and the sealant layer at the edge of the measurement sample, the peel adhesive strength of the laminate was measured using a tensile tester at an angle of 90°, a pulling rate of 300 mm / min, and room temperature. This peel adhesive strength was taken as the adhesive strength. As a result, the adhesive strength was 1.5 (N / 15 mm).

[0132] (Reference example 6) As the paper substrate, commercially available coated paper (product name: Cormorant, manufactured by Fuji Kako Co., Ltd., basis weight: 55.0 g / m 2A laminate having a paper substrate, an adhesive layer, and a sealant layer in this order was obtained in the same manner as in Reference Example 5, except that a cormorant paper (coated surface smoothness: 410 seconds) was used. The sealant layer was laminated on the uncoated side of the cormorant paper. The adhesive strength was measured in the same manner as in Reference Example 5, and was found to be 1.8 (N / 15 mm).

[0133] (Reference example 7) As the paper substrate, commercially available pure white roll paper (product name: Kinshachi, manufactured by Nagoya Pulp Co., Ltd., basis weight: 40.0 g / m) was used. 2 The adhesive composition was prepared by blending a polyether polyol (manufactured by Mitsui Chemicals, Inc., product name: Takelac A953) as the base agent, an aromatic polyisocyanate (manufactured by Mitsui Chemicals, Inc., product name: Takenate A93) as the curing agent, and ethyl acetate as the solvent, to prepare an organic solvent-based adhesive composition with a solids concentration of 33% by mass. The blending ratio (by mass) of the components was (base agent):(curing agent) = 16:1.

[0134] The adhesive composition was applied to the sealant layer using a dry laminating device and then dried with hot air to form a coating film consisting only of nonvolatile components. The coating amount of the nonvolatile coating film was approximately 2.1 g / m 2 The coating film and the paper substrate were placed face to face, and a nip roll was used to bond the paper substrate and the sealant layer via the coating film. The coating film was then cured by aging at 40°C for 2 days. This dry lamination method yielded a laminate having a paper substrate, an adhesive layer, and a sealant layer in this order. The laminate of Reference Example 7 differs from the laminates of Reference Examples 5 and 6 in that an organic solvent-based adhesive composition was used. The adhesive strength of the laminate of Reference Example 7 was measured using the same procedure as Reference Example 5. The resulting adhesive strength was 0.6 (N / 15 mm).

[0135] Comparing the adhesive strengths of Reference Examples 5, 6, and 7, when adhering a CPP film as a sealant layer to a paper substrate, the adhesive strength was higher when using a solventless adhesive composition than when using an organic solvent-based adhesive composition. When adhering a non-stretched film such as a CPP film to a paper substrate, drying at a lower temperature than when adhering an oriented film is required to suppress thermal shrinkage due to heating. It is believed that when an organic solvent-based adhesive composition is used, the organic solvent cannot be sufficiently removed by low-temperature drying, and the remaining organic solvent penetrates into the paper substrate during adhesion, reducing adhesiveness. Therefore, it was shown that the use of a solventless adhesive composition allows for the non-stretched film to be adhered to the paper substrate with sufficiently high strength. [Industrial Applicability]

[0136] According to the present disclosure, there is provided a printed matter in which ink is printed at high resolution on a paper substrate, and a laminate and a packaging bag including the printed matter in which ink is printed at high resolution on a paper substrate. [Explanation of symbols]

[0137] 100, 105...printed matter, 10...paper base material, 10A...one side, 10B...other side, 20...primer layer, 30, 30A...electrostatic ink layer, 31...halftone dot, 32...printed surface, 200, 202, 204...laminated body, S...adhesive layer, S1...first adhesive layer, S2...second adhesive layer, 40...sealant layer, 50...intermediate layer, 60...coating layer, 150, 155...packaging bag, 101...sealed portion, 102...storage portion, 120...opening means, 121...half-cut line, 124...easy-open processing portion.

Claims

1. A paper substrate, a primer layer on one side of the paper substrate, and an electrostatic ink layer covering at least a portion of the primer layer, A printed matter, wherein the circularity of the halftone dots constituting the electrostatic ink layer is 0.60 or more.

2. The printed matter according to claim 1 , wherein the surface smoothness of the paper substrate is 8 seconds or more.

3. A paper substrate, a primer layer on one side of the paper substrate, and an electrostatic ink layer covering at least a portion of the primer layer, A printed matter, wherein the surface smoothness of the paper substrate is 8 seconds or more.

4. The printed matter according to any one of claims 1 to 3, wherein the surface smoothness of the paper substrate is 300 seconds or less.

5. The paper base has a basis weight of 100 g / m ２ The printed matter according to any one of claims 1 to 3, wherein:

6. 4. The printed matter according to claim 1, wherein the absolute value of the difference between the ink coverage rate and the ink area rate of the electrostatic ink layer is 7.0% or less.

7. A laminate comprising the printed matter according to any one of claims 1 to 3, and an adhesive layer and a sealant layer on the other surface of the paper substrate, in this order from the paper substrate side.

8. A laminate comprising the printed matter according to any one of claims 1 to 3 and a coating layer of a thermoplastic resin on the other side of the paper substrate.

9. The laminate according to claim 7 , wherein the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof.

10. The laminate of claim 7 , wherein the sealant layer is a non-oriented film.

11. A packaging bag formed by heat-sealing the sealant layers of the laminate according to claim 7 together.

12. A packaging bag formed by heat-sealing the coating layers of the laminate according to claim 8 .

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