Laminate and packaging bag, as well as producing method of packaging bag

Abstract

To provide a laminate excellent in reliability after heat sealing, while reducing environmental load.SOLUTION: A laminate 300 comprises a base film 10, a primer layer 40, an adhesive layer 30, and a sealant layer 20 in this order, wherein at least a portion between the primer layer 40 and the adhesive layer 30 includes an electrostatic ink layer 50, the adhesive layer 30 includes a solvent-free adhesive composition containing a polyol component and a polyisocyanate component, its cured product, or a mixture thereof, and when the sealant layers 20 are heat-sealed under conditions of any temperature within the range of 120 to 160°C, 0.2 MPa, for 0.5 seconds, the increase in laminate strength based on the laminate strength before heat sealing is 0.8 (N / 15 mm) or more, thereby providing the laminate 300.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Packaging bags are known for containing and sealingly preserving beverages, food products, and the like. Thin film or sheet packaging is used as the packaging bag. Various pieces of information, such as product information, brand information, and manufacturer information, are printed on such packaging bags. Digital printers using electrostatic ink compositions are known as a printing method for such packaging bags.

[0003] For example, Patent Document 1 proposes applying a primer resin to a first flexible substrate such as a PET film to obtain a coated surface, performing electrostatic printing on the coated surface using a digital printer (HP's Indigo 20000 label and packaging digital printer), and then applying a crosslinking composition. Patent Document 2 proposes using a cured product of a polyol, a polyisocyanate, and an epoxy compound as an adhesive layer to form a laminate that can maintain sufficiently high adhesive strength between layers even under high-temperature hot water conditions such as retort treatment.

[0004] On the other hand, from the viewpoint of reducing the environmental load, development of adhesives that do not contain organic solvents is underway. For example, Patent Document 3 proposes a two-component curing solventless adhesive containing a polyisocyanate component and a polyol component, and a composite film for packaging foods, beverages, medicines, quasi-drugs, etc. [Prior art documents] [Patent documents]

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

[0006] Electrostatic ink layers printed on laminates by digital printing have weak cohesion and low laminate strength. When a laminate is obtained by adhering a printed surface having such an electrostatic ink layer with a solventless adhesive composition, there is a concern that the laminate strength will be further reduced. Therefore, the present disclosure provides a laminate that has excellent reliability after heat sealing while reducing the environmental impact. The present disclosure also provides a packaging bag that has excellent sealing reliability while reducing the environmental impact, and a method for manufacturing such a packaging bag. [Means for solving the problem]

[0007] One aspect of the present disclosure provides a laminate comprising, in this order, a base film, a primer layer, an adhesive layer, and a sealant layer, wherein an electrostatic ink layer is provided at least partially between the primer layer and the adhesive layer, and the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture of these, and when the sealant layers are heat-sealed together at a temperature within a range of 120 to 160°C, at 0.2 MPa, for 0.5 seconds, the increase in laminate strength from the level before heat-sealing is 0.8 (N / 15 mm) or more.

[0008] When the sealant layers of the laminate are heat-sealed under the above conditions, the laminate strength of the heat-sealed portion increases by 0.8 (N / 15 mm) or more. Thus, the laminate can have a sufficiently higher laminate strength after heat sealing than before heat sealing. Therefore, the laminate has excellent reliability after heat sealing. Furthermore, the adhesive layer of the laminate contains a solventless adhesive composition, a cured product thereof, or a mixture thereof, thereby reducing the environmental impact.

[0009] One aspect of the present disclosure provides a laminate comprising a base film, a primer layer, an adhesive layer, and a sealant layer in this order, wherein an electrostatic ink layer is provided at least partially between the primer layer and the adhesive layer, and the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture of these, wherein the ratio of the thickness of the adhesive layer after the sealant layers are heat-sealed together under conditions of 0.2 MPa, a temperature within a range of 120 to 160°C, and a time period of 0.5 seconds to the thickness of the adhesive layer before heat sealing is less than 95%.

[0010] When the sealant layers of the laminate are heat-sealed under the above conditions, the ratio of the thickness of the adhesive layer after heat sealing to the thickness of the adhesive layer before heat sealing is less than 95%. In such a laminate, for example, the components of the solventless adhesive layer tend to penetrate into the electrostatic ink layer upon heat sealing and react sufficiently with the components of the electrostatic ink layer or the primer layer. This allows the laminate strength after heat sealing to be sufficiently higher than before heat sealing. Therefore, the laminate has excellent reliability after heat sealing. Furthermore, the adhesive layer of the laminate contains a solventless adhesive composition, a cured product thereof, or a mixture thereof, thereby reducing the environmental impact.

[0011] One aspect of the present disclosure provides a packaging bag constructed by heat-sealing the sealant layers of the laminate. Because this packaging bag includes the laminate, the heat-sealed portion (sealed portion) has sufficiently high lamination strength. This packaging bag is highly reliable because it can prevent the bag from breaking due to impact during transportation, etc. Furthermore, because the packaging bag includes a laminate having an adhesive layer containing a solventless adhesive composition, a cured product thereof, or a mixture thereof, it can reduce environmental impact. Furthermore, because digital printing (electrostatic printing) can be used, the design freedom of the packaging bag can be sufficiently increased.

[0012] One aspect of the present disclosure provides a packaging bag comprising: a sealed portion where the sealant layers of a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer in this order are heat-sealed together; and a storage portion formed between the unsealed portions of the pair of laminates, wherein the laminates have an electrostatic ink layer at least partially between the primer layer and the adhesive layer, and the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture of these, and when the sealant layers in the unsealed portion are heat-sealed together at a temperature within a range of 120 to 160°C, at 0.2 MPa, for 0.5 seconds, the packaging bag provides an increase in laminate strength of 0.8 (N / 15 mm) or more relative to the strength before heat sealing.

[0013] The packaging bag includes a laminate that increases the laminate strength by 0.8 (N / 15 mm) or more when the sealant layers in the non-sealed portion are heat-sealed under the above conditions. Because the laminate constituting the sealed portion of such a packaging bag has sufficiently high laminate strength and the sealed portion is sufficiently strong, bag breakage due to impacts during transportation, etc., can be suppressed. Therefore, the packaging bag has excellent sealing reliability. Furthermore, the packaging bag includes a laminate whose adhesive layer contains a solventless adhesive composition, a cured product thereof, or a mixture thereof, thereby reducing the environmental impact. Furthermore, the use of digital printing allows for a sufficiently high degree of freedom in the design of the packaging bag.

[0014] One aspect of the present disclosure provides a packaging bag comprising: a sealed portion where the sealant layers of a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer in this order are heat-sealed together; and a storage portion formed between the non-sealed portions of the pair of laminates, wherein the laminates have an electrostatic ink layer at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture of these; and the thickness of the adhesive layer after the sealant layers in the non-sealed portion have been heat-sealed together at a temperature in the range of 120 to 160°C, at 0.2 MPa, for 0.5 seconds is less than 95% of the thickness of the adhesive layer in the non-sealed portion before heat-sealing.

[0015] When the sealant layers of the packaging bag are heat-sealed under the above conditions, the ratio of the thickness of the adhesive layer after heat sealing to the thickness of the adhesive layer before heat sealing is less than 95%. It is believed that, for example, the components of the solventless adhesive layer penetrate into the electrostatic ink layer by heat sealing such a packaging bag and react sufficiently with the components of the electrostatic ink layer or the primer layer. Therefore, the laminate constituting the sealed portion has sufficiently high lamination strength, and the sealed portion is sufficiently strong, thereby preventing bag breakage due to impact during transportation, etc. Therefore, the packaging bag has excellent sealing reliability. Furthermore, since the adhesive layer of the packaging bag contains a solventless adhesive composition, a cured product thereof, or a mixture thereof, the environmental impact can be reduced. Furthermore, the use of digital printing allows for ample freedom in packaging bag design.

[0016] One aspect of the present disclosure provides a packaging bag comprising: a sealed portion where the sealant layers of a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer in this order are heat-sealed together; and a storage portion formed between the non-sealed portions of the pair of laminates, wherein the laminates have an electrostatic ink layer at least partially between the primer layer and the adhesive layer, and the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture of these, and the laminate strength of the laminate at the sealed portion is at least 0.8 (N / 15 mm) higher than the laminate strength of the laminate at the non-sealed portion.

[0017] In the above-mentioned packaging bag, the laminate strength of the laminate in the sealed portion is at least 0.8 (N / 15 mm) higher than the laminate strength of the laminate in the non-sealed portion. In such a packaging bag, the laminate constituting the sealed portion has sufficiently high laminate strength, and the sealed portion is sufficiently strong, so that the bag can be prevented from breaking due to impact during transportation, etc. Therefore, the above-mentioned packaging bag has excellent sealing reliability. Furthermore, since the above-mentioned packaging bag has an adhesive layer comprising a laminate containing a solventless adhesive composition, a cured product thereof, or a mixture thereof, the environmental impact can be reduced. Furthermore, since digital printing can be used, the degree of freedom in the design of the packaging bag can be sufficiently increased.

[0018] One aspect of the present disclosure provides a packaging bag comprising: a sealed portion formed by heat-sealing the sealant layers of a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer in this order; and a storage portion formed between non-sealed portions of the pair of laminates, wherein the laminate comprises an electrostatic ink layer at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture of these; and the ratio of the thickness of the adhesive layer in the sealed portion to the thickness of the adhesive layer in the non-sealed portion is less than 95%.

[0019] In the packaging bag, the ratio of the thickness of the adhesive layer in the sealed portion to the thickness of the adhesive layer in the unsealed portion is less than 95%. In such a packaging bag, for example, it is believed that components of the solventless adhesive layer penetrate into the electrostatic ink layer by heat sealing in the sealed portion and react with components of the electrostatic ink layer or the primer layer. Therefore, the laminate constituting the sealed portion has sufficiently high lamination strength, and the sealed portion is sufficiently strong, thereby preventing bag breakage due to impact during transportation, etc. Therefore, the packaging bag has excellent sealing reliability. Furthermore, the packaging bag has an adhesive layer containing a solventless adhesive composition, a cured product thereof, or a mixture thereof, thereby reducing the environmental impact.

[0020] One aspect of the present disclosure provides a method for producing a packaging bag, comprising a step of heat-sealing the sealant layers of the laminate at a temperature within a range of 120 to 160°C, at 0.2 MPa, and for 0.5 seconds to form a sealed portion.

[0021] The packaging bag manufacturing method includes a step of heat-sealing the sealant layers together under the above conditions to form a sealed portion, which tends to cause, for example, components of the solventless adhesive layer to penetrate into the electrostatic ink layer and react with components of the electrostatic ink layer or the primer layer. This allows the laminate strength of the sealed portion of the packaging bag to be significantly higher than that of the unsealed portion. Therefore, the packaging bag manufacturing method described above can produce a packaging bag with excellent sealing reliability. Furthermore, because the adhesive layer of the packaging bag contains a solventless adhesive composition, a cured product thereof, or a mixture thereof, the packaging bag manufacturing method described above can reduce environmental impact. [Effects of the Invention]

[0022] It is possible to provide a laminate that has excellent reliability after heat sealing while reducing the environmental load. It is also possible to provide a packaging bag that has excellent sealing reliability while reducing the environmental load, and a method for manufacturing such a packaging bag. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 2 is a cross-sectional view showing an example of a laminate. [Figure 2] FIG. 10 is a cross-sectional view showing another example of a laminate. [Figure 3] FIG. 1 is a plan view showing an example of a packaging bag. [Figure 4] FIG. 10 is a perspective view showing another example of a packaging bag. [Figure 5] 1 is a graph of Table 1, with the horizontal axis representing the sealing temperature (° C.) and the vertical axis representing the laminate strength (N / 15 mm) after heat sealing. [Figure 6] 1 is a graph of Table 2, with the horizontal axis representing the sealing temperature (° C.) and the vertical axis representing the laminate strength (N / 15 mm) after heat sealing. DETAILED DESCRIPTION OF THE INVENTION

[0024] 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.

[0025] 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.

[0026] [Laminate] The first embodiment of the laminate is a laminate comprising a base film, a primer layer, an adhesive layer, and a sealant layer in this order, and an electrostatic ink layer is provided at least partially between the primer layer and the adhesive layer. The adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture of these. When the sealant layers are heat-sealed together at a temperature within the range of 120 to 160°C, at 0.2 MPa, and for 0.5 seconds, the increase in laminate strength compared to before heat sealing is 0.8 (N / 15 mm) or more.

[0027] A second embodiment of the laminate is a laminate comprising a base film, a primer layer, an adhesive layer, and a sealant layer in this order, and an electrostatic ink layer is provided at least partially between the primer layer and the adhesive layer, and the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture of these, and the ratio of the thickness of the adhesive layer after the sealant layers have been heat-sealed together under conditions of 0.2 MPa, 0.5 seconds, and any temperature within a range of 120 to 160°C to the thickness of the adhesive layer before heat sealing is less than 95%.

[0028] Fig. 1 is a cross-sectional view showing an example of a laminate common to the first and second embodiments. Fig. 1 shows a cross-section along the lamination direction (thickness direction) of a laminate 300. The laminate 300 comprises a base film 10, a primer layer 40, an adhesive layer 30, and a sealant layer 20, in this order. The laminate 300 comprises an electrostatic ink layer 50 on at least a portion of the primer layer 40 and the adhesive layer 30. The primer layer 40 and the electrostatic ink layer 50 are in contact with each other, and the electrostatic ink layer 50 and the adhesive layer 30 are in contact with each other.

[0029] When the sealant layers 20 of the laminate 300 are heat-sealed together at a temperature within the range of 120 to 160°C, under 0.2 MPa, and for 0.5 seconds, the increase in laminate strength from the level before heat-sealing may be 0.8 (N / 15 mm) or more. The laminate strength of such a laminate 300 can be sufficiently improved by heat-sealing. The increase in laminate strength from heat-sealing may occur, for example, when the sealant layers 20 are heat-sealed together under the above conditions, causing components contained in the adhesive layer 30 to permeate the electrostatic ink layer 50 and react with components of the electrostatic ink layer 50 or the primer layer 40. To further increase the increase in laminate strength from heat-sealing, the increase in laminate strength from the level before heat-sealing may be 0.9 (N / 15 mm) or more, or 1.0 (N / 15 mm) or more. The increase in laminate strength from the level before heat sealing may be 3.0 (N / 15 mm) or less, or 2.0 (N / 15 mm) or less. The increase in laminate strength from the level before heat sealing may be in the range of, for example, 0.8 to 3.0 (N / 15 mm), or 0.8 to 2.0 (N / 15 mm).

[0030] Heat sealing may be performed to bond the sealant layers 20 of a single laminate 300 together, or to bond the sealant layers 20 of a pair of laminates 300 together. Heat sealing may be performed, for example, using a thermal ramp machine (product name: HG-100-2, manufactured by Toyo Seiki Seisakusho, Ltd.) at a temperature within a range of 120 to 160°C, at 0.2 MPa, and for 0.5 seconds. The increase in laminate strength relative to the strength before heat sealing can be calculated by subtracting the laminate strength before heat sealing from the laminate strength after heat sealing under the above conditions.

[0031] Among the above conditions, "any temperature within the range of 120 to 160°C" does not mean that the increase in laminate strength satisfies the above numerical range at all temperatures within the range of 120 to 160°C, but rather that the increase in laminate strength when heat-sealed at any temperature from 120 to 160°C satisfies the above numerical range. That is, the increase in laminate strength when heat-sealed at 120°C may satisfy the above numerical range, the increase in laminate strength when heat-sealed at 140°C may satisfy the above numerical range, or the increase in laminate strength when heat-sealed at 160°C may satisfy the above numerical range. Furthermore, the increase in laminate strength when heat-sealed at any temperature within the range of 120 to 140°C may satisfy the above numerical range, or the increase in laminate strength when heat-sealed at any temperature within the range of 140 to 160°C may satisfy the above numerical range. The increase in laminate strength may satisfy the above numerical range at all temperatures within the range of 120 to 160°C, or may satisfy the above numerical range at all temperatures within the range of 120 to 140°C.

[0032] The lamination strength in the present disclosure is the peel adhesive strength as defined in JIS K 6854-1:1999 "Adhesives - Test method for peel adhesive strength - Part 1: 90° peel." Specifically, it can be measured by the method described in the examples of the present disclosure.

[0033] The laminate strength before heat sealing may be 0.5 (N / 15 mm) or more, or 0.6 (N / 15 mm) or more, from the viewpoint of maintaining sufficient strength of the laminate 300. The laminate strength before heat sealing may be 2.0 (N / 15 mm) or less. The laminate strength before heat sealing may be, for example, 0.5 to 2.0 (N / 15 mm).

[0034] From the viewpoint of sufficiently maintaining the strength of the laminate 300 and further improving the reliability of the laminate after heat sealing, the laminate strength after heat sealing may be 1.3 (N / 15mm) or more, or 1.4 (N / 15mm) or more. Furthermore, the laminate strength after heat sealing may be 3.0 (N / 15mm) or less. The laminate strength after heat sealing may be, for example, 1.3 to 3.0 (N / 15mm).

[0035] The substrate film 10 may have a flexible substrate. The flexible substrate may include, for example, a thermoplastic polymer film. Examples of flexible substrates include biaxially oriented polypropylene (OPP), biaxially oriented polypropylene (BOPP), polyethylene terephthalate (PET), oriented polyamide (OPA), solid polypropylene (CPP), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and nylon (NY) film.

[0036] The base film 10 may include, for example, a vapor-deposited film (transparent vapor-deposited film) having a resin layer such as a PET film and a barrier layer (vapor-deposited layer) on the resin layer. This can improve the sealing performance when the laminate 300 is used as a packaging material. Examples of the barrier layer include a vapor-deposited layer of a metal oxide (for example, silica or alumina). The thickness of the base film 10 may be 7 to 150 μm, 10 to 100 μm, or 12 to 80 μm. A specific example of a transparent vapor-deposited film is a transparent vapor-deposited PET film in which a transparent vapor-deposited layer is formed on a PET film. The base film 10 may include a nylon film such as a barrier nylon film.

[0037] The primer layer 40 may contain a resin. Examples of the resin include polyvinyl alcohol resin, cellulose-based resin, polyester, polyamine, polyethyleneimine resin, polyamide resin, polyurethane, polyacrylic polymer, hydroxyl-containing resin, carboxyl-containing resin, and amine-based polymer. The presence of the primer layer 40 allows smooth printing of the electrostatic ink composition using a digital printer. Furthermore, the adhesion of the electrostatic ink layer 50 to the primer layer 40 can be improved. The amount of resin applied to the primer layer 40 is, for example, 0.01 to 1.5 g / m. 2 and may be 0.05 to 1.0 g / m 2 may be.

[0038] The laminate 300 may have a printing surface 52 on the primer layer 40. An electrostatic ink layer 50 is provided on the printing surface 52. The electrostatic ink layer 50 may be composed of an electrostatic ink composition. The electrostatic ink layer 50 is provided by electrostatic printing using a digital printing machine. As shown in FIG. 1 , the electrostatic ink layer 50 is provided so as to cover at least a portion of the surface of the primer layer 40. That is, the electrostatic ink layer 50 may be provided so as to be interspersed between the primer layer 40 and the adhesive layer 30. This allows the laminate 300 to have plain areas.

[0039] The electrostatic ink layer 50 may be a single color, or may be configured by laminating multiple electrostatic ink compositions of different colors. The electrostatic ink layer 50 and the adhesive layer 30 are adjacent to each other. In FIG. 1, the multiple electrostatic ink layers 50 are of the same height, but this is not limited to this. The electrostatic ink layer 50 may also be multiple, or may be continuous. In FIG. 1, the electrostatic ink layer 50 is interrupted in the horizontal direction. The interrupted portions of the electrostatic ink layer 50 are blank areas. The electrostatic ink layer 50 may be formed without interruption in the horizontal direction, and may be a laminate with no portions where the adhesive layer 30 and the primer layer 40 are in direct contact.

[0040] The electrostatic ink composition that constitutes the electrostatic ink layer 50 is an ink composition used in liquid electrophotographic printing, i.e., electrostatic printing, and is printed on the primer layer 40. The electrostatic ink composition may contain a colorant or pigment, such as a dye, and a resin. In addition to these, the electrostatic ink composition may also contain a carrier fluid or carrier liquid. It may also contain a charge director, a charge adjuvant, a surfactant, a viscosity modifier, an emulsifier, and other additives. It may also contain a component that permeates through the adhesive layer 30 (e.g., a polyisocyanate component).

[0041] The thickness of the electrostatic ink layer 50 can be adjusted by changing the ink coverage. Ink coverage represents the ratio of halftone dot area per unit area. For example, when a predetermined area is uniformly printed with a single color, the ink coverage is 100%. On the other hand, the ink coverage of an unprinted area (plain area) is 0%. The ink coverage can be calculated based on these two values. For example, applying 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 is printed once, the ink coverage is 50%. When printing with multiple colors of ink, the ink coverage for each color of ink is calculated, and the sum of these values ​​can be used as the ink coverage of the target electrostatic ink layer 50. The ink coverage is set on the digital press (for example, HP's Indigo 20000 label and packaging digital press) and can be adjusted by specifying the desired value in the ink coverage setting.

[0042] The ink coverage of the electrostatic ink layer 50 may be 500% or less, 450% or less, or 400% or less, from the viewpoint of improving laminate strength and increasing design freedom using multiple inks. Furthermore, the ink coverage of the electrostatic ink layer 50 may be 200% or more, 250% or more, or 300% or more, from the viewpoint of further improving laminate strength by allowing the components of the adhesive layer to sufficiently penetrate by heat sealing. The ink coverage may be in the range of, for example, 200 to 500%, 200 to 450%, or 300 to 450%.

[0043] The adhesive layer 30 is composed of a solventless adhesive composition, its cured product, or a mixture thereof. The adhesive composition may be a two-component curing type. The adhesive layer 30 contains two components: a polyisocyanate component and a polyol component. These components may at least partially react with each other to form a cured product. The cured product may also contain polyurethane. The adhesive layer 30 containing the above two components is in direct contact with the electrostatic ink layer 50. Such solventless adhesive components have lower molecular weights than organic solvent-based adhesive components, allowing them to sufficiently penetrate the electrostatic ink layer 50 by heat sealing, thereby improving laminate strength. Furthermore, because no organic solvents are used, the environmental impact can be significantly reduced.

[0044] The thickness of the adhesive layer 30 before heat sealing may be 0.5 to 5.0 μm, 0.6 to 3.0 μm, or 0.8 to 2.0 μm, which allows a good balance between laminate strength and design.

[0045] The ratio α of the thickness of the adhesive layer 30 after heat sealing to the thickness of the adhesive layer 30 before heat sealing may be less than 95%. When the ratio α is within the above range, for example, the components of the adhesive layer 30 sufficiently penetrate into the electrostatic ink layer 50 during heat sealing and sufficiently react with the components of the electrostatic ink layer 50 or the primer layer 40. Such a laminate 300 has excellent reliability after heat sealing because the layers are firmly bonded to each other. From the perspective of further strengthening the adhesion between the layers, the ratio α may be 93% or less, 90% or less, 85% or less, or 80% or less. The ratio α may be 60% or more, or 70% or more. The ratio α may be, for example, 60% or more but less than 95%.

[0046] The thickness of the adhesive layer 30 before heat sealing and the thickness of the adhesive layer 30 after heat sealing can be measured specifically by the method described in the examples of the present disclosure.

[0047] The polyisocyanate component may contain a hexamethylene diisocyanate derivative (hereinafter, sometimes referred to as an "HDI derivative"). This increases the cohesive force of the electrostatic ink layer 50 and the laminate strength of the adhesive layer 30. Furthermore, when heat-sealing is performed under the above conditions, the increase in laminate strength compared to the strength before heat-sealing can be further increased. The HDI derivative may be a bifunctional derivative of hexamethylene diisocyanate. The HDI derivative is an aliphatic diisocyanate and penetrates the electrostatic ink layer 50 more easily than aromatic diisocyanates. This improves compatibility between the electrostatic ink layer 50 and the adhesive layer 30, improving the cross-linking effect between the adhesive layer 30 and the electrostatic ink layer 50. This improves the adhesion between the electrostatic ink layer 50 and the adhesive layer 30.

[0048] The HDI derivative may be a trifunctional derivative of HDI (hexamethylene diisocyanate). Such a trifunctional derivative penetrates the electrostatic ink layer 50 and crosslinks with the components of the electrostatic ink layer 50. This further increases the cohesive force of the electrostatic ink layer 50, thereby further increasing the laminate strength of the adhesive layer 30. By including both a bifunctional derivative and a trifunctional derivative as the HDI derivative, the HDI derivative can be sufficiently penetrated into the electrostatic ink layer 50, further promoting the crosslinking reaction with the components of the electrostatic ink layer 50. Therefore, even when the electrostatic ink layer 50 is thick, the laminate strength of the adhesive layer 30 can be maintained sufficiently high.

[0049] In the adhesive layer 30 (adhesive composition), the content of the trifunctional derivative of HDI may be higher than the content of the difunctional derivative of HDI. This allows the crosslinking reaction to proceed sufficiently in the adhesive layer 30 and the electrostatic ink layer 50, improving the strength of the adhesive layer 30 and the electrostatic ink layer 50 and sufficiently increasing the adhesive strength between the adhesive layer 30 and the electrostatic ink layer 50. From this perspective, the mass ratio of the trifunctional derivative to the total of the bifunctional derivative and the trifunctional derivative may be 55% by mass or more, or may be 60% by mass or more. On the other hand, from the perspective of maintaining the flexibility of the adhesive layer 30 and the electrostatic ink layer 50, the mass ratio of the trifunctional derivative to the total of the bifunctional derivative and the trifunctional derivative may be 85% by mass or less, 80% by mass or less, or 75% by mass or less. An example of the mass ratio of the trifunctional derivative to the total of the bifunctional derivative and the trifunctional derivative is 55 to 85% by mass.

[0050] 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.

[0051] 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.

[0052] The polyisocyanate component may further contain a polyisocyanate having two or more isocyanate groups in one molecule, which is different from the HDI derivative. This allows for flexibility in designing the laminate 300 according to the desired properties. Examples of such polyisocyanate monomers include aromatic diisocyanates, aromatic alicyclic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates.

[0053] Aromatic diisocyanates are highly reactive and easily cured, which allows for rapid production of the laminate 300. Examples of aromatic aliphatic diisocyanates include m- or p-phenylene diisocyanate or a mixture thereof, 2,4- or 2,6-tolylene diisocyanate or a mixture thereof (TDI), 4,4'-, 2,4'-, or 2,2'-diphenylmethane diisocyanate or a mixture thereof (MDI), 4,4'-toluidine diisocyanate (TODI), 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, and 1,5-naphthalene diisocyanate (NDI).

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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).

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] Examples of low molecular weight polyols having four or more hydroxyl groups include tetramethylolmethane, pentaerythritol, dipentaerythritol, D-sorbitol, xylitol, D-mannitol, and D-mannite.

[0065] 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.

[0066] The acid halides include those derived from the above-mentioned polybasic acids, such as oxalic acid dichloride, adipic acid dichloride, and sebacic acid dichloride.

[0067] In the adhesive layer 30 (adhesive composition), the mass ratio of the polyisocyanate component may be higher than the mass ratio of the polyol component. Specifically, the mass ratio of the polyisocyanate component to the polyol component may be 1 or more, 1.2 or more, or even 1.4 or more. In this way, by increasing the mass ratio of the polyisocyanate component to the polyol component, the curing reaction is promoted and the adhesion and curing process can be sufficiently shortened. From the same viewpoint, the mass ratio of the polyisocyanate component to the polyol component may be 4 or less, or even 3 or less. An example of the mass ratio of the polyisocyanate component to the polyol component is 1 to 4.

[0068] Examples of the sealant layer 20 include a non-oriented polypropylene film (CPP film), a linear low-density polyethylene film (LLDPE film), and a low-density polyethylene film (LDPE). The thickness of the sealant layer 20 may be 10 to 150 μm, 20 to 100 μm, or 30 to 80 μm.

[0069] FIG. 2 is a cross-sectional view showing another example of a laminate common to the first and second embodiments. FIG. 2 shows a cross-section of a laminate 310 taken along the lamination direction (thickness direction). The laminate 310 includes, in this order, a base film 10, a primer layer 40, an electrostatic ink layer 51, a first adhesive layer 30, an intermediate layer 21, a second adhesive layer 31, and a sealant layer 20. The primer layer 40 and the electrostatic ink layer 51 are in contact with each other, and the electrostatic ink layer 51 and the first adhesive layer 30 are in contact with each other. The electrostatic ink layer 51 is formed to cover the entire primer layer 40. Therefore, the laminate 310 does not have any solid areas. However, in a modified example, the electrostatic ink layer 51 may be interrupted, similar to the electrostatic ink layer 50 of the laminate 300 shown in FIG. 2, and the laminate 310 may have solid areas.

[0070] The intermediate layer 21 may have a flexible substrate. Examples of flexible substrates include biaxially oriented polypropylene (BOPP), polyethylene terephthalate (PET), oriented polyamide (OPA), and nylon films. The intermediate layer 21 may be, 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, or may be a metal foil or a barrier film. Examples of metal foils include aluminum foil.

[0071] The first adhesive layer 30 and the second adhesive layer 31 may have the same components and thickness as the adhesive layer 30 in Fig. 1. The other layers of the laminate 310 may be as described for the laminate 300 in Fig. 1.

[0072] The adhesive layer 30 (first adhesive layer 30) and / or the second adhesive layer 31 (adhesive composition) may contain a surface modifier that improves adhesion between the primer layer 40 or electrostatic ink layer 51, the intermediate layer 21, and the sealant layer 20. When the intermediate layer 21 is a barrier layer made of metal or the like, the adhesive strength and sealing strength between the adhesive layers 30, 31 and the barrier layer can be further increased. When the barrier layer has a metal layer (aluminum layer) such as a metal foil (aluminum foil) or a metal film (aluminum film), the adhesive layers 30, 31 (adhesive composition) can further improve adhesion to the metal layer by containing a surface modifier.

[0073] 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.

[0074] The adhesive composition constituting the adhesive layer 30 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.

[0075] The laminate of the present disclosure is not limited to the structures shown in Figures 1 and 2. For example, it may have the following laminate structure. In each example, the rightmost layer is the sealant layer 20. In each example, the layers are arranged in order from left to right. The following third adhesive layer may be the same adhesive layer as the adhesive layer 30 (first adhesive layer) and the second adhesive layer 31, or may be a different adhesive layer. Note that the layer structure of the laminate is not limited to the following examples.

[0076] Example 1) PET film / primer layer / electrostatic ink layer / adhesive layer / LLDPE film (linear low-density polyethylene film) Example 2) Nylon film / primer layer / electrostatic ink layer / adhesive layer / LLDPE film Example 3) Transparent vapor-deposited PET film / primer layer / electrostatic ink layer / adhesive layer / CPP film (non-oriented polypropylene film) Example 4) Barrier nylon film / primer layer / electrostatic ink layer / adhesive layer / CPP film Example 5) Transparent vapor-deposited PET film / primer layer / electrostatic ink layer / first adhesive layer / PET film / second adhesive layer / CPP film Example 6) Transparent vapor-deposited PET film / primer layer / electrostatic ink layer / first adhesive layer / nylon film / second adhesive layer / CPP film Example 7) Transparent vapor-deposited PET film / primer layer / electrostatic ink layer / first adhesive layer / PET film / second adhesive layer / nylon film / third adhesive layer / CPP film Example 8) Transparent vapor-deposited PET film / primer layer / electrostatic ink layer / first adhesive layer / nylon film / second adhesive layer / PET film / third adhesive layer / CPP film Example 9) Transparent vapor-deposited PET film / primer layer / electrostatic ink layer / first adhesive layer / PET film / second adhesive layer / PET film / third adhesive layer / CPP film Example 10) OPP film / primer layer / electrostatic ink layer / adhesive layer / CPP film Example 11) OPP film / primer layer / electrostatic ink layer / adhesive layer / LLDPE film Example 12) Nylon film / primer layer / electrostatic ink layer / adhesive layer / CPP film Example 13) PET film / primer layer / electrostatic ink layer / adhesive layer / CPP film Example 14) PET film / primer layer / electrostatic ink layer / first adhesive layer / nylon film / second adhesive layer / LLDPE film Example 15) PET film / primer layer / electrostatic ink layer / first adhesive layer / aluminum foil / second adhesive layer / LDPE film Example 16) PET film / primer layer / electrostatic ink layer / first adhesive layer / aluminum foil / second adhesive layer / nylon film / third adhesive layer / LLDPE film

[0077] [Packaging bag] A packaging bag according to one embodiment includes a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer, in that order, each having a sealed portion formed by heat-sealing the sealant layers of the laminates, and a storage portion formed between the unsealed portions of the pair of laminates. The laminates include an electrostatic ink layer at least partially between the primer layer and the adhesive layer, and the adhesive layer includes a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof. The laminate may be the laminate of the first or second embodiment described above. Therefore, the description of laminates 300 and 310 also applies to this embodiment.

[0078] FIG. 3 is a plan view showing an example of a packaging bag of this embodiment. The packaging bag 100 in FIG. 3 is formed using a laminate 300 (310). The packaging bag 100 is formed by bonding the sealant layers 20 of a pair of laminates 300 (310) together. The surface 300A (310A) on the base film 10 side becomes the outer surface of the packaging bag 100. The packaging bag 100 has a sealed portion 101 formed by bonding the peripheral edges of a pair of film-like, approximately rectangular laminates 300 (310) together, and a storage portion 102 formed between the pair of laminates 300 (310) by the sealed portion 101. That is, the side edges, bottom edge, and top edge of the packaging bag 100 are sealed by the sealed portion 101. The packaging bag 100 has a non-sealed portion (sheet portion) 103 surrounded by the sealed portion 101, and the storage portion 102 in which the packaged item (e.g., food) is stored. It should be noted that the seal portion 101 at the lower end may be sealed after the packaged item is filled into the storage portion 102. The seal portion 101 is formed by heat-sealing the sealant layers 20 together.

[0079] At least one of the laminates 300 (310) constituting the packaging bag 100 includes, in this order, a base film 10, a primer layer 40, an electrostatic ink layer 50 (51), an adhesive layer 30, and a sealant layer 20. Each layer may be the same as described above.

[0080] The sealed portion 101 may be formed by heat-sealing and bonding together the sealant layers 20 of the laminate 300 (310). Alternatively, the sealed portion 101 may be formed by heat-sealing one of the sealant layers 20 of the laminate 300 (310) to another layer other than the sealant layer.

[0081] When the sealant layers 20 in the non-sealed portions 103 of the packaging bag 100 are heat-sealed at a temperature within the range of 120 to 160°C, at 0.2 MPa, and for 0.5 seconds, the increase in laminate strength from the level before heat-sealing may be 0.8 (N / 15 mm) or more. When the sealed portions 101 of the packaging bag 100 having such non-sealed portions 103 are heat-sealed under the above conditions, for example, components contained in the adhesive layer 30 may penetrate the electrostatic ink layer 50 (51) and react with components of the electrostatic ink layer 50 (51) or the primer layer 40. In such a packaging bag 100, the layers are firmly bonded to each other in the sealed portions 101, preventing the bag from breaking due to impacts during transportation. Therefore, the packaging bag 100 has excellent sealing reliability.

[0082] From the viewpoint of further strengthening the adhesion between the layers, the increase in laminate strength from the level before heat sealing may be 0.9 (N / 15 mm) or more, or 1.0 (N / 15 mm) or more. The increase in laminate strength from the level before heat sealing may be 3.0 (N / 15 mm) or less, or 2.0 (N / 15 mm) or less. The increase in laminate strength from the level before heat sealing may be, for example, 0.8 to 3.0 (N / 15 mm), or 0.8 to 2.0 (N / 15 mm). The heat sealing conditions may be the same as those described for the laminate 300 above.

[0083] In the packaging bag 100, the laminate strength of the laminate 300 (310) in the sealed portion 101 may be 0.8 (N / 15 mm) or more higher than the laminate strength of the laminate 300 (310) in the non-sealed portion 103. In a packaging bag 100 having such a non-sealed portion 103 and sealed portion 101, for example, components contained in the adhesive layer 30 may penetrate the electrostatic ink layer 50 (51) in the sealed portion 101 and react with components of the electrostatic ink layer 50 (51) or the primer layer 40. In such a packaging bag 100, the layers are firmly bonded to each other in the sealed portion 101, which can prevent the bag from breaking due to impacts during transportation, etc. Therefore, the packaging bag 100 has excellent sealing reliability.

[0084] From the viewpoint of further strengthening the adhesion between the layers, the laminate strength of the laminate 300 (310) in the sealed portion 101 may be 0.9 (N / 15 mm) or more higher, or 1.0 (N / 15 mm) or more higher, than the laminate strength of the laminate 300 (310) in the non-sealed portion 103. That is, the increase in the laminate strength of the laminate 300 (310) in the sealed portion 101 based on the laminate strength of the laminate 300 (310) in the non-sealed portion 103 may be 0.9 (N / 15 mm) or more, or 1.0 (N / 15 mm) or more. Furthermore, the increase in the laminate strength of the laminate 300 (310) in the sealed portion 101 based on the laminate strength of the laminate 300 (310) in the non-sealed portion 103 may be 3.0 (N / 15 mm) or less, or 2.0 (N / 15 mm) or less. The increase in the laminate strength of the laminate 300 (310) in the sealed portion 101 based on the laminate strength of the laminate 300 (310) in the non-sealed portion 103 may be, for example, 0.8 to 3.0 (N / 15 mm), or 0.8 to 2.0 (N / 15 mm).

[0085] In the packaging bag 100, the thickness ratio β of the adhesive layer 30 after the sealant layers 20 in the non-sealed portions 103 are heat-sealed at a temperature within a range of 120 to 160°C, at 0.2 MPa, for 0.5 seconds, relative to the thickness of the adhesive layer 30 in the non-sealed portions 103 before heat sealing may be less than 95%. When the ratio β is within the above range, for example, the components of the adhesive layer 30 may sufficiently penetrate the electrostatic ink layer 50 (51) during heat sealing and react with the components of the electrostatic ink layer 50 (51) or the primer layer 40. In such a packaging bag 100, the layers are firmly bonded together in the sealed portions 101, preventing the bag from breaking due to impacts during transportation, etc. Therefore, the packaging bag 100 has excellent sealing reliability. From the viewpoint of further strengthening the adhesion between the layers, the ratio β may be 93% or less, 90% or less, 85% or less, or 80% or less. The ratio β may be, for example, 60% or more, or 70% or more. The ratio β may be, for example, 60% or more and less than 95%. The heat sealing conditions may be the same as those described for the laminate 300 above.

[0086] In the packaging bag 100, the ratio γ of the thickness of the adhesive layer 30 in the sealed portion 101 to the thickness of the adhesive layer 30 in the non-sealed portion 103 may be less than 95%. When the ratio γ is within the above range, for example, the components of the adhesive layer 30 in the sealed portion 101 may sufficiently penetrate the electrostatic ink layer 50 (51) and react with the components of the electrostatic ink layer 50 (51) or the primer layer 40. In such a packaging bag 100, the layers are firmly bonded to each other in the sealed portion 101, preventing the bag from breaking due to impact during transportation, etc. Therefore, the packaging bag 100 has excellent sealing reliability. From the viewpoint of further strengthening the adhesion between the layers, the ratio γ may be 93% or less, 90% or less, 85% or less, or 80% or less. The ratio γ may be, for example, 60% or more or 70% or more. The ratio γ may be, for example, 60% or more but less than 95%.

[0087] The size of the packaging bag 100 may be within a range that allows the formation of the sealed portion 101, the non-sealed portion 103, and the containing portion 102. Furthermore, the shape of the packaging bag 100 is not particularly limited. The shape of the outer edge of the packaging bag 100 is not limited to a straight line, and part of the outer edge may be curved. The width of the sealed portion 101 may be 5 to 30 mm, 10 to 25 mm, or 12 to 20 mm. By keeping the width of the sealed portion 101 within this range, the volume of the containing portion 102 can be sufficiently increased while further improving the seal strength.

[0088] The volume of the storage section 102 may be 1 to 1000 mL, 5 to 500 mL, 10 to 100 mL, or 15 to 50 mL from the viewpoint of further improving the seal strength while ensuring a sufficient volume for placing the contents inside.

[0089] The packaging bag 100 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 slitting 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.

[0090] A package including the packaging bag 100 and the contents may be produced by placing the contents in the storage section 102 of the packaging bag 100. The contents are sealed in the storage section 102. The contents may be a liquid, such as a liquid, an emulsion, a particle dispersion, a gel, or a mixture thereof. Examples of the contents include food, beverages, medicines, hair care products, and cosmetics.

[0091] The procedure for manufacturing the packaging bag 100 using the laminate 300 (310) is described below. The method for manufacturing the packaging bag 100 may include a step of heat-sealing the sealant layers 20 of the laminate 300 (310) together at a temperature in the range of 120 to 160°C, at 0.2 MPa, for 0.5 seconds to form the sealed portion 101. Here, heat-sealing at a temperature in the range of 120 to 160°C means that the maximum temperature during heat-sealing is a temperature in the range of 120 to 160°C.

[0092] That is, the maximum temperature during heat sealing may be 120°C, 140°C, or 160°C. Furthermore, the maximum temperature during heat sealing may be any temperature within the range of 120 to 140°C, or any temperature within the range of 140 to 160°C.

[0093] Specifically, the method for manufacturing the packaging bag 100 begins by preparing a pair of laminates 300 (310) cut to a predetermined shape as packaging materials. Then, the sealant layers 20 on one side of each laminate 300 (310) are placed opposite each other, and the sealant layers 20 are heat-sealed together under the above-described conditions to form a sealed portion 101. This forms sealed portions 101 at the top and side edges, forming a U-shaped unsealed portion 103 surrounded by the sealed portions 101. In this manner, a packaging bag 110 is obtained in which only the top end (or only the bottom end) is unsealed, as shown in FIG. 4. The top end (or bottom end) is then heat-sealed under the above-described conditions, and an opening means 120 is then formed to obtain the packaging bag 100. In some examples, the packaging bag of this embodiment may have some edges unsealed, as shown in FIG. 4.

[0094] When producing a package, the contents to be packaged are filled from the unsealed upper end (or lower end). Then, the laminates 300 (310) are heat-sealed together at the upper end (or lower end) to form a sealed portion 101 at the upper end (or lower end). In this way, a package comprising the packaging bag 100 and the contents contained therein can be produced.

[0095] The packaging bag 100 and the packaging body are manufactured using the laminate 300 (310). This reduces the environmental impact and can increase consumer purchasing motivation.

[0096] Although several examples have been described above, this embodiment is not limited to the above examples. For example, the shape of the package is not limited to a four-sided bag, and may be, for example, a two-sided bag, a three-sided bag, a folded bag, or a standing pouch.

[0097] The present disclosure includes the following embodiments and modifications thereof. [1] A laminate comprising a substrate film, a primer layer, an adhesive layer, and a sealant layer in this order, an electrostatic ink layer is provided at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; A laminate in which, when the sealant layers are heat-sealed together at a temperature in the range of 120 to 160°C, at 0.2 MPa, for 0.5 seconds, the increase in laminate strength compared to before heat sealing is 0.8 (N / 15 mm) or more. [2] The laminate according to [1], wherein the ratio of the thickness of the adhesive layer after heat sealing under the conditions to the thickness of the adhesive layer before heat sealing is less than 95%. [3] A laminate comprising a substrate film, a primer layer, an adhesive layer, and a sealant layer in this order, an electrostatic ink layer is provided at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; A laminate in which the ratio of the thickness of the adhesive layer after the sealant layers are heat-sealed together under conditions of a temperature in the range of 120 to 160°C, 0.2 MPa, and 0.5 seconds to the thickness of the adhesive layer before heat sealing is less than 95%. [4] The laminate according to any one of [1] to [3], wherein the ink coverage of the electrostatic ink layer is 200 to 500%. [5] The laminate according to any one of [1] to [4], wherein the polyisocyanate component contains a derivative of hexamethylene diisocyanate. [6] The laminate according to [5], wherein the polyisocyanate component further contains a polyisocyanate different from the derivative of hexamethylene diisocyanate. [7] The laminate according to [5] or [6], wherein the derivative of hexamethylene diisocyanate includes a bifunctional derivative of hexamethylene diisocyanate and a trifunctional derivative of hexamethylene diisocyanate. [8] The laminate according to [7], wherein the content of the trifunctional derivative is higher than the content of the bifunctional derivative. [9] The laminate according to any one of [1] to [8], wherein the mass ratio of the polyisocyanate component to the polyol component is 1 or more.

[10] The laminate according to any one of [1] to [9], wherein the polyol component contains a polyether polyol.

[11] The laminate according to any one of [1] to

[10] , wherein the adhesive composition contains a surface modifier.

[12] A packaging bag formed by heat-sealing the sealant layers of the laminate according to any one of [1] to

[11] above.

[13] A packaging bag comprising: a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer in this order; a sealed portion formed by heat-sealing the sealant layers of the laminates; and a storage portion formed between the unsealed portions of the pair of laminates, the laminate includes an electrostatic ink layer at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; A packaging bag in which, when the sealant layers in the non-sealed portions are heat-sealed at a temperature in the range of 120 to 160°C, at 0.2 MPa, for 0.5 seconds, the increase in laminate strength compared to before heat sealing is 0.8 (N / 15 mm) or more.

[14] A packaging bag comprising: a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer in this order; a sealed portion formed by heat-sealing the sealant layers of the laminates; and a storage portion formed between the unsealed portions of the pair of laminates, the laminate includes an electrostatic ink layer at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; A packaging bag in which the ratio of the thickness of the adhesive layer in the non-sealed portions after the sealant layers in the non-sealed portions have been heat-sealed under conditions of a temperature in the range of 120 to 160°C, 0.2 MPa, and a time period of 0.5 seconds to the thickness of the adhesive layer in the non-sealed portions before heat sealing is less than 95%.

[15] A packaging bag comprising: a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer in this order; a sealed portion formed by heat-sealing the sealant layers of the laminates; and a storage portion formed between the unsealed portions of the pair of laminates, the laminate includes an electrostatic ink layer at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; A packaging bag, wherein the laminate strength of the laminate in the sealed portion is at least 0.8 (N / 15 mm) higher than the laminate strength of the laminate in the non-sealed portion.

[16] A packaging bag comprising: a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer in this order; a sealed portion formed by heat-sealing the sealant layers of the laminates; and a storage portion formed between the unsealed portions of the pair of laminates, the laminate includes an electrostatic ink layer at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; A packaging bag, wherein the ratio of the thickness of the adhesive layer in the sealed portion to the thickness of the adhesive layer in the non-sealed portion is less than 95%.

[17] A method for producing a packaging bag, comprising a step of heat-sealing the sealant layers of the laminate described in any one of [1] to

[11] above at a temperature in the range of 120 to 160°C, at 0.2 MPa, for 0.5 seconds to form a sealed portion. [Example]

[0098] The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0099] Example 1 [Preparation of laminate with ink coverage of 400% 1] A commercially available nylon film (NY film, manufactured by Unitika Ltd., product name: Emblem ON, thickness: 15 μm) was prepared as the substrate film, and a commercially available linear low-density polyethylene film (LLDPE film, thickness: 40 μm) was prepared as the sealant layer. An aqueous primer resin (a resin containing polyethyleneimine, manufactured by Michelman, product name: DP050) was applied to one side of this NY film to form a primer layer. The amount of aqueous polyethyleneimine applied was 0.10 to 0.18 g / m. 2 The water-based primer resin was applied to the NY film so that the

[0100] 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. The ink coverage of the electrostatic ink layer was 400% (cyan (C) 100% + magenta (M) 100% + yellow (Y) 100% + white (W) 100%). The electrostatic ink composition used was an electrostatic ink composition (HP Indigo Electroink) containing a thermoplastic resin containing a copolymer of ethylene acrylic acid and ethylene methacrylic acid.

[0101] As polyisocyanate components, a derivative of diphenylmethane isocyanate (MDI) (MDI derivative, manufactured by Mitsui Chemicals, Inc.), a derivative of hexamethylene diisocyanate (HDI derivative I, manufactured by Mitsui Chemicals, Inc.), and a derivative of hexamethylene diisocyanate (HDI derivative II, manufactured by Mitsui Chemicals, Inc.) were prepared. HDI derivative I contained a bifunctional derivative of hexamethylene diisocyanate. HDI derivative II contained a trifunctional derivative of hexamethylene diisocyanate. The MDI derivative, HDI derivative I, and HDI derivative II were blended in a mass ratio of MDI derivative:HDI derivative I:HDI derivative II = 100:14:28 to prepare a polyisocyanate component.

[0102] A polyether polyol (manufactured by Mitsui Chemicals, Inc., product name: XRN-21B) was prepared as the polyol component. The polyol component and the polyisocyanate component were blended so that the mass ratio of the polyol component to the polyisocyanate component was 142 / 65 (≒2.18), and a surface modifier was further added to prepare a solventless adhesive composition containing the surface modifier. Hereinafter, this adhesive composition may be referred to as "Adhesive 1." This adhesive composition was heated to approximately 60°C and applied to one side of an electrostatic ink layer formed on a substrate film using a roll coater to form a coating film with a predetermined thickness. The amount of adhesive composition applied was approximately 2.0 g / m 2The coating film and the sealant layer (LLDPE film) were overlapped so that they faced each other, and a nip roll was used to bond the electrostatic ink layer on the base film and the sealant layer via the coating film (adhesive composition). The adhesive composition was then cured by aging at 45°C for 2 days. This method yielded a laminate having the base film, primer layer, electrostatic ink layer, adhesive layer, and sealant layer in this order.

[0103] [Measurement of laminate strength before heat sealing] 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 (manufactured by Toyo Seiki Seisakusho, Ltd.) at an angle of 90°, a pulling rate of 300 mm / min, and room temperature. This peel adhesive strength was taken as the laminate strength. The measurement results are shown in Table 1.

[0104] [Measurement of laminate strength after heat sealing] A pair of laminates was prepared, and the sealant layers were bonded together by heat sealing. Heat sealing was performed using a thermal gradient machine (product name: HG-100-2, manufactured by Toyo Seiki Seisakusho Co., Ltd.) under conditions of a sealing pressure of 0.2 MPa, a sealing time of 0.5 seconds, and a sealing temperature of 140°C. The laminate strength after heat sealing was measured using the same procedure as in [Measurement of adhesive layer thickness before heat sealing]. The difference in laminate strength before and after heat sealing was then calculated by subtracting the laminate strength before heat sealing from the measured laminate strength after heat sealing. The difference in laminate strength before and after heat sealing thus determined was taken as the increase in laminate strength based on the value before heat sealing. The results are shown in Table 1.

[0105] Examples 2 to 7 A laminate was prepared using the same procedure as in Example 1, and the laminate strength of the laminate before heat sealing was measured using the same procedure as in Example 1. Then, the sealant layers of a pair of laminates were attached to each other using the same procedure as in Example 1, except that the heat sealing temperature was set to the temperature shown in Table 1, and the laminate strength after heat sealing was measured. The increase in laminate strength was calculated based on the strength before heat sealing. The results are shown in Table 1.

[0106] Example 8 A laminate was prepared using the same procedure as in Example 1, except that a commercially available solventless adhesive composition was used instead of the solventless adhesive composition used in Example 1. This adhesive composition was prepared by blending a polyether polyol (manufactured by Toyo-Morton Co., Ltd., product name: EA-N373B, hereinafter sometimes referred to as "(A)") as the base agent and an aromatic polyisocyanate (manufactured by Toyo-Morton Co., Ltd., product name: EA-N373A, hereinafter sometimes referred to as "(B)") as the curing agent. The blending ratio (by mass) of the components was (A):(B) = 50:100. Hereinafter, this adhesive composition may be referred to as "Adhesive 2." The laminate strength of the laminate before heat sealing was measured using the same procedure as in Example 1. Furthermore, the sealant layers of a pair of laminates were bonded together at a sealing temperature of 140°C using the same procedure as in Example 1, and the laminate strength after heat sealing was measured. The increase in laminate strength was calculated based on the strength before heat sealing. The results are shown in Table 1.

[0107] (Examples 9 to 14) A laminate was prepared using the same procedure as in Example 8, and the laminate strength of the laminate before heat sealing was measured using the same procedure as in Example 8. Then, the sealant layers of a pair of laminates were attached to each other using the same procedure as in Example 8, and the laminate strength after heat sealing was measured using the same procedure as in Example 8, except that the heat sealing temperature was set to the temperature shown in Table 1. The increase in laminate strength was calculated based on the strength before heat sealing. The results are shown in Table 1.

[0108] (Comparative Example 1) An organic solvent-based adhesive composition with a solids concentration of 33% by mass was prepared by blending an aliphatic polyester polyol (manufactured by Mitsui Chemicals, Inc., product name: Takelac A626, hereinafter sometimes referred to as "(C)") as the base agent, a polyisocyanate (manufactured by Mitsui Chemicals, Inc., product name: Takenate A65, hereinafter sometimes referred to as "(D)") as the curing agent, and ethyl acetate as the solvent. The blending ratio (by mass) of the components was (C):(D) = 16:1. Hereinafter, this adhesive composition may be referred to as "Adhesive 3." The laminate strength of the laminate before heat sealing was measured using the same procedure as in Example 1. Furthermore, the sealant layers of a pair of laminates were bonded together using the same procedure as in Example 1, and the laminate strength was measured. The increase in laminate strength was calculated based on the value before heat sealing. The results are shown in Table 1.

[0109] (Comparative Examples 2 to 6) A laminate was prepared using the same procedure as in Comparative Example 1, and the laminate strength of the laminate before heat sealing was measured using the same procedure as in Comparative Example 1. Then, the sealant layers of a pair of laminates were attached to each other using the same procedure as in Comparative Example 1, except that the heat sealing temperature was set to the temperature shown in Table 1, and the laminate strength after heat sealing was measured. The increase in laminate strength was calculated based on the strength before heat sealing. The results are shown in Table 1.

[0110] [Table 1]

[0111] Figure 5 shows a graph of the change in laminate strength for each adhesive, with the horizontal axis representing the sealing temperature (°C) and the vertical axis representing the laminate strength (N / 15 mm) after heat sealing. Each point in Figure 5 represents each Example and Comparative Example in Table 1. As shown in Figure 5, the use of adhesive 1 resulted in the highest laminate strength after heat sealing. The use of adhesive 3 resulted in the lowest laminate strength after heat sealing. Furthermore, the highest laminate strength after heat sealing was achieved at a sealing temperature of 120 to 140°C. This indicates that when adhesive 1 is used, heat sealing at a high sealing temperature increases the laminate strength.

[0112] As shown in Table 1, when solvent-free adhesive compositions Adhesive 1 and Adhesive 2 were used, the increase in laminate strength relative to the value before heat sealing was 0.8 (N / 15 mm) or more at sealing temperatures of 160°C, 140°C, 120°C, and 100°C. On the other hand, at sealing temperatures of 80°C, 60°C, and 35°C, the increase in laminate strength relative to the value before heat sealing was less than 0.8 (N / 15 mm). This is thought to be due to the fact that the solvent-free adhesive layer penetrated into the electrostatic ink layer due to heat sealing at high temperatures, causing the components of the adhesive layer to react with the components of the electrostatic ink layer or primer layer. On the other hand, when Adhesive 3, an organic solvent-based adhesive composition, was used, the increase in laminate strength relative to the value before heat sealing was less than 0.8 (N / 15 mm), regardless of the sealing temperature. This indicates that solvent-free adhesive compositions are more likely to penetrate into heat sealing at higher temperatures than organic solvent-based adhesive compositions, thereby improving laminate strength.

[0113] [Preparation of laminate with ink coverage of 400% 2] Example 15 A laminate was produced in the same manner as in Example 1, except that the base film was changed to a commercially available biaxially oriented polypropylene film (OPP film, thickness: 30 μm) and the sealant layer was changed to a commercially available unoriented polypropylene film (CPP film, thickness: 30 μm). That is, the type of adhesive composition used was Adhesive 1. The laminate strength before heat sealing was measured in the same manner as in Example 1. The sealant layers of a pair of laminates were attached to each other at a sealing temperature of 140°C, and the laminate strength after heat sealing was measured in the same manner as in Example 1, and the increase in laminate strength was calculated based on the value before heat sealing. The results are shown in Table 2.

[0114] (Examples 16 to 19) A laminate was prepared using the same procedure as in Example 15, and the laminate strength of the laminate before heat sealing was measured using the same procedure as in Example 15. Then, the sealant layers of a pair of laminates were attached to each other using the same procedure as in Example 15, and the laminate strength after heat sealing was measured using the same procedure as in Example 15, except that the heat sealing temperature was set to the temperature shown in Table 2. The increase in laminate strength was calculated based on the strength before heat sealing. The results are shown in Table 2.

[0115] (Comparative Example 7) A laminate was produced using the same procedure as in Comparative Example 1, except that the base film was changed to a commercially available biaxially oriented polypropylene film (OPP film, thickness: 30 μm) and the sealant layer was changed to a commercially available unoriented polypropylene film (CPP film, thickness: 30 μm). That is, the type of adhesive composition used was Adhesive 3. The laminate strength before heat sealing was measured using the same procedure as in Comparative Example 1. The sealant layers of a pair of laminates were attached to each other at a sealing temperature of 140°C, and the laminate strength after heat sealing was measured using the same procedure as in Comparative Example 1, and the increase in laminate strength was calculated based on the value before heat sealing. The results are shown in Table 2.

[0116] (Comparative Examples 8 to 11) A laminate was prepared using the same procedure as in Comparative Example 7, and the laminate strength of the laminate before heat sealing was measured using the same procedure as in Comparative Example 7. Thereafter, the sealant layers of a pair of laminates were attached to each other using the same procedure as in Comparative Example 7, except that the heat sealing temperature was set to the temperature shown in Table 2, and the laminate strength after heat sealing was measured, and the increase in laminate strength based on the value before heat sealing was calculated. The results are shown in Table 2.

[0117] [Table 2]

[0118] Figure 6 shows a graph of the change in laminate strength for each adhesive, with the horizontal axis representing the sealing temperature (°C) and the vertical axis representing the laminate strength (N / 15 mm) after heat sealing. Each point in Figure 6 represents each Example and Comparative Example in Table 2. As shown in Figure 6, when adhesive 1 was used, the laminate strength after heat sealing was greater than when adhesive 3 was used. It was also confirmed that the laminate strength after heat sealing tended to increase when the sealing temperature was high. This indicates that even when the types of base film and sealant layer were changed, the laminate strength increased when heat sealing was performed at a high sealing temperature in a laminate using adhesive 1.

[0119] As shown in Table 2, when Adhesive 1, a solvent-free adhesive composition, was used, the increase in laminate strength relative to the value before heat sealing was 0.8 (N / 15 mm) or more at sealing temperatures of 160°C, 140°C, and 120°C. On the other hand, at sealing temperatures of 100°C and 80°C, the increase in laminate strength relative to the value before heat sealing was less than 0.8 (N / 15 mm). This is likely due to the fact that, as in Table 1, heat sealing at high temperatures caused the solvent-free adhesive layer to penetrate into the electrostatic ink layer, resulting in reaction of the adhesive layer components with the electrostatic ink layer or primer layer components. On the other hand, when Adhesive 3, an organic solvent-based adhesive composition, was used, the increase in laminate strength relative to the value before heat sealing was less than 0.8 (N / 15 mm), regardless of the sealing temperature. This demonstrates that solvent-free adhesive compositions are more likely to penetrate into heat sealing at higher temperatures than organic solvent-based adhesive compositions, thereby improving laminate strength.

[0120] As shown in Tables 1 and 2, regardless of the type of substrate film and sealant layer, by using a solventless adhesive composition, it was shown that the laminate strength of the laminate can be improved by heat sealing at 120 to 160°C, even when an electrostatic ink layer is used.

[0121] [Preparation of a laminate with 200% ink coverage] Example 20 A laminate was prepared using the same procedure as in Example 1, except that the ink coverage of the electrostatic ink layer was 200% (100% cyan (C) + 100% white (W)), and the laminate strength before heat sealing was measured. A pair of laminates was then prepared, and the sealant layers of the pair of laminates were bonded together by heat sealing using the same procedure as in Example 1, except that the sealing temperature was 120°C. The laminate strength after heat sealing was measured using the same procedure as in Example 1, and the increase in laminate strength was calculated based on the value before heat sealing. The configuration of the laminate is shown in Table 3, and the measurement results of the laminate strength are shown in Table 4.

[0122] (Comparative Example 12) A laminate was prepared in the same manner as in Example 20, except that Adhesive 3 was used as the adhesive composition, and the laminate strength before heat sealing was measured. A pair of laminates was then prepared, and the sealant layers of the pair of laminates were attached to each other by heat sealing in the same manner as in Example 20. The laminate strength after heat sealing was measured in the same manner as in Example 20, and the increase in laminate strength based on the value before heat sealing was calculated. The configuration of the laminate is shown in Table 3, and the measurement results of the laminate strength are shown in Table 4.

[0123] Example 21 A laminate was prepared using the same procedure as in Example 15, except that the ink coverage of the electrostatic ink layer was 200% (100% cyan (C) + 100% white (W)), and the laminate strength before heat sealing was measured. A pair of laminates was then prepared, the sealing temperature was set to 140°C, and the sealant layers of the pair of laminates were bonded together by heat sealing using the same procedure as in Example 15. The laminate strength after heat sealing was measured using the same procedure as in Example 15, and the increase in laminate strength was calculated based on the value before heat sealing. The configuration of the laminate is shown in Table 3, and the measurement results of the laminate strength are shown in Table 4.

[0124] (Comparative Example 13) A laminate was prepared in the same manner as in Example 21, except that the adhesive composition used was Adhesive 3, and the laminate strength before heat sealing was measured. A pair of laminates was then prepared, and the sealant layers of the pair of laminates were bonded together by heat sealing in the same manner as in Example 21. The sealing temperature was 140°C. The laminate strength after heat sealing was measured in the same manner as in Example 21, and the increase in laminate strength was calculated based on the value before heat sealing. The configuration of the laminate is shown in Table 3, and the measurement results of the laminate strength are shown in Table 4.

[0125] [Creating a laminate with 0% ink coverage] (Comparative Example 14) The NY film used in Example 1 was prepared as the substrate film, and the LLDPE film used in Example 1 was prepared as the sealant layer. An aqueous primer resin (a resin containing polyethyleneimine, manufactured by Michelman, product name: DP050) was applied to one side of this NY film to form a primer layer. At this time, the amount of aqueous polyethyleneimine applied was 0.10 to 0.18 g / m 2 The water-based primer resin was applied to the NY film so that the

[0126] The adhesive 1 used in Example 1 was applied directly to the primer layer using the same procedure as in Example 1. Then, a sealant layer was attached using the same procedure as in Example 1. Using this method, a laminate was obtained having a substrate film, a primer layer, an adhesive layer, and a sealant layer in this order. Because the produced laminate did not have an electrostatic ink layer, the ink coverage was 0%.

[0127] The laminate strength before heat sealing was measured using the same procedure as in Example 1. Then, a pair of laminates was prepared, and the sealant layers of the pair of laminates were attached to each other by heat sealing using the same procedure as in Example 1. The sealing temperature was 140°C. The laminate strength after heat sealing was measured using the same procedure as in Example 1, and the increase in laminate strength was calculated based on the value before heat sealing. The configuration of the laminate is shown in Table 3, and the measurement results of the laminate strength are shown in Table 4.

[0128] (Comparative Example 15) A laminate with an ink coverage of 0% was prepared using the same procedure as in Comparative Example 14, except that the adhesive composition was changed to Adhesive 3, and the laminate strength before heat sealing was measured. The sealant layers of a pair of laminates were attached to each other by heat sealing using the same procedure as in Comparative Example 14. The sealing temperature was 140°C. The laminate strength after heat sealing was measured using the same procedure as in Comparative Example 14, and the increase in laminate strength was calculated based on the value before heat sealing. The configuration of the laminate is shown in Table 3, and the measurement results of the laminate strength are shown in Table 4.

[0129] (Comparative Example 16) A laminate with an ink coverage of 0% was prepared using the same procedure as in Comparative Example 14, except that the adhesive composition was changed to Adhesive 2, and the laminate strength before heat sealing was measured. The structure of the laminate is shown in Table 3, and the measurement results of the laminate strength are shown in Table 4. In Comparative Example 14, the laminate strength after heat sealing was not measured, and therefore this is indicated by "-" in Table 4.

[0130] [Table 3]

[0131] [Table 4]

[0132] As shown in Tables 3 and 4, in Examples 20 and 21, which used Adhesive 1, a solvent-free adhesive composition, the increase in laminate strength from the level before heat sealing was 0.8 (N / 15 mm) or more, even when the ink coverage was 200%. On the other hand, in Comparative Examples 12 and 13, which used Adhesive 3, an organic solvent-based adhesive composition, the increase in laminate strength after heat sealing was less than 0.8 (N / 15 mm). This suggests that even when the ink coverage was 200%, heat sealing at high temperatures allowed the solvent-free adhesive layer to penetrate into the electrostatic ink layer, and the components of the adhesive layer reacted with the components of the electrostatic ink layer or primer layer.

[0133] As shown in Comparative Examples 14 to 16, it was confirmed that when the ink coverage was 0%, regardless of the type of adhesive composition, heat sealing did not significantly increase the laminate strength. This suggests that the increase in laminate strength due to heat sealing is caused by the components of the adhesive composition penetrating into the electrostatic ink layer.

[0134] [Measurement of adhesive layer thickness] To confirm that the adhesive layer had penetrated into the electrostatic ink layer, the thickness of the adhesive layer was measured before and after heat sealing. The thickness of the adhesive layer was measured for the laminates of Example 1, Comparative Example 1, Example 8, Comparative Example 14, Comparative Example 15, and Comparative Example 16. The procedure for measuring the thickness of the adhesive layer is as follows.

[0135] Each laminate prepared in each Example and Comparative Example was cut into a size of 0.5 cm length x 1.0 cm width and embedded in photocurable resin. An ultramicrotome (product name: EM UC6, manufactured by Leica Microsystems) was used to prepare a block cross section so that the cross section of the laminate could be observed. The obtained block cross section was observed under an optical microscope (product name: BX53M, manufactured by Olympus Corporation). Using a scale bar, the thickness of the adhesive layer at any position on the observed cross section of the laminate was measured. Five block cross sections were prepared, and measurements were performed once for each block cross section. The thickness of the adhesive layer before heat sealing was calculated as the average of the five measurements.

[0136] Each laminate was then heat-sealed to bond the heat-sealed layers together. Heat-sealing was performed using a thermal gradient machine (product name: HG-100-2, manufactured by Toyo Seiki Seisakusho Co., Ltd.) under conditions of a sealing pressure of 0.2 MPa, a sealing time of 0.5 seconds, and a sealing temperature of 140°C. The thickness of the adhesive layer after heat-sealing was then calculated using the same procedure as for measuring the thickness of the adhesive layer before heat-sealing. Based on the calculated adhesive layer thickness, the ratio α (%) of the thickness of the adhesive layer after heat-sealing to the thickness of the adhesive layer before heat-sealing was calculated. The configuration of the laminate is shown in Table 5, and the measurement results of the adhesive layer thickness are shown in Table 6.

[0137] [Table 5]

[0138] [Table 6]

[0139] As shown in Table 6, in Examples 1 and 8, which used a solvent-free adhesive layer, the ratio α of the adhesive layer thickness after heat sealing to the adhesive layer thickness before heat sealing was less than 95%. Furthermore, in Comparative Example 1, which used an organic solvent-based adhesive layer, the thickness of the adhesive layer hardly changed even after heat sealing. On the other hand, as shown in Comparative Examples 14, 15, and 16, even when a solvent-free adhesive was used, the thickness of the adhesive layer hardly changed even after heat sealing when the ink coverage was 0%. This suggests that heat sealing at 140°C allows the components of the solvent-free adhesive composition to penetrate into the electrostatic ink layer, reducing the thickness of the adhesive layer. This is thought to improve the laminate strength by allowing the components of the solvent-free adhesive to penetrate into the electrostatic ink layer. The above suggests that the laminate strength of the laminate can be improved by heat sealing by combining a solvent-free adhesive layer with an electrostatic ink layer. [Industrial Applicability]

[0140] According to the present disclosure, it is possible to provide a laminate that has excellent reliability after heat sealing while reducing the environmental load, and also to provide a packaging bag that has excellent sealing reliability while reducing the environmental load, and a method for manufacturing such a packaging bag. [Explanation of symbols]

[0141] 300, 310... laminate, 300A, 310A... surface, 10... base film, 20... sealant layer, 21... intermediate layer, 30... adhesive layer (first adhesive layer), 31... adhesive layer (second adhesive layer), 40... primer layer, 50, 51... electrostatic ink layer, 52... printed surface, 100, 110... packaging bag, 101... sealed portion, 102... storage portion, 103... non-sealed portion, 120... opening means, 121... half-cut line, 124... easy-open processing portion.

Claims

1. A laminate comprising a substrate film, a primer layer, an adhesive layer, and a sealant layer in this order, an electrostatic ink layer is provided at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; A laminate in which, when the sealant layers are heat-sealed together at a temperature in the range of 120 to 160°C, at 0.2 MPa, for 0.5 seconds, the increase in laminate strength from the level before heat-sealing is 0.8 (N / 15 mm) or more.

2. The laminate according to claim 1 , wherein the ratio of the thickness of the adhesive layer after heat sealing under the above conditions to the thickness of the adhesive layer before heat sealing is less than 95%.

3. A laminate comprising a substrate film, a primer layer, an adhesive layer, and a sealant layer in this order, an electrostatic ink layer is provided at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; A laminate in which the ratio of the thickness of the adhesive layer after the sealant layers are heat-sealed together under conditions of a temperature in the range of 120 to 160°C, 0.2 MPa, and a time period of 0.5 seconds to the thickness of the adhesive layer before heat sealing is less than 95%.

4. The laminate according to any one of claims 1 to 3, wherein the ink coverage of the electrostatic ink layer is 200 to 500%.

5. The laminate according to any one of claims 1 to 3, wherein the polyisocyanate component comprises a derivative of hexamethylene diisocyanate.

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

7. The laminate according to claim 5 , wherein the derivative of hexamethylene diisocyanate includes a bifunctional derivative of hexamethylene diisocyanate and a trifunctional derivative of hexamethylene diisocyanate.

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

9. The laminate according to any one of claims 1 to 3, wherein the mass ratio of the polyisocyanate component to the polyol component is 1 or more.

10. The laminate according to any one of claims 1 to 3, wherein the polyol component comprises a polyether polyol.

11. The laminate according to any one of claims 1 to 3, wherein the adhesive composition comprises a surface modifier.

12. A packaging bag formed by heat-sealing the sealant layers of the laminate according to any one of claims 1 to 3.

13. A packaging bag comprising: a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer in this order, wherein the sealant layers of the laminates are heat-sealed together; and a storage section formed between the unsealed sections of the pair of laminates, the laminate includes an electrostatic ink layer at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; When the sealant layers in the non-sealed portions are heat-sealed at a temperature in the range of 120 to 160°C, at 0.2 MPa, and for 0.5 seconds, the increase in laminate strength from the level before heat-sealing is 0.8 (N / 15 mm) or more.

14. A packaging bag comprising: a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer in this order, wherein the sealant layers of the laminates are heat-sealed together; and a storage section formed between the unsealed sections of the pair of laminates, the laminate includes an electrostatic ink layer at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; A packaging bag in which the ratio of the thickness of the adhesive layer after the sealant layers in the non-sealed portions are heat-sealed under conditions of a temperature in the range of 120 to 160°C, 0.2 MPa, and a time period of 0.5 seconds to the thickness of the adhesive layer in the non-sealed portions before heat-sealing is less than 95%.

15. A packaging bag comprising: a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer in this order, wherein the sealant layers of the laminates are heat-sealed together; and a storage section formed between the unsealed sections of the pair of laminates, the laminate includes an electrostatic ink layer at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; A packaging bag, wherein the laminate strength of the laminate in the sealed portion is at least 0.8 (N / 15 mm) higher than the laminate strength of the laminate in the non-sealed portion.

16. A packaging bag comprising: a pair of laminates each having a base film, a primer layer, an adhesive layer, and a sealant layer in this order, wherein the sealant layers of the laminates are heat-sealed together; and a storage section formed between the unsealed sections of the pair of laminates, the laminate includes an electrostatic ink layer at least partially between the primer layer and the adhesive layer; the adhesive layer comprises a solventless adhesive composition containing a polyol component and a polyisocyanate component, a cured product thereof, or a mixture thereof; A packaging bag, wherein the ratio of the thickness of the adhesive layer in the sealed portion to the thickness of the adhesive layer in the non-sealed portion is less than 95%.

17. A method for producing a packaging bag, comprising a step of heat-sealing the sealant layers of the laminate according to any one of claims 1 to 3 together at a temperature in the range of 120 to 160°C, at 0.2 MPa, and for 0.5 seconds to form a sealed portion.

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