JP7688835B2 - Laminate and packaging container - Google Patents

Description

The present invention relates to a laminate and a packaging container.

Environmentally friendly packaging containers are attracting attention. For example, there is a trend to replace the plastic laminate that makes up packaging containers with paper. When the weight ratio of paper in the laminate exceeds 50%, it is classified as paper for recycling purposes.

JP 2012-200990 A

Heat sealing is a known method for producing packaging containers using laminates. For example, the inner surfaces of a laminate are joined together by heat sealing. This produces a pouch such as a pillow pouch. In heat sealing, heat is applied to the outer surface of the laminate. The heat transferred from the outer surface to the inner surface melts the material on the inner surface, joining the inner surfaces of the laminate.

The thermal conductivity of paper is lower than that of plastic. For this reason, heat applied to the outer surface is less likely to be transmitted to the inner surface. Therefore, if heat sealing is performed at the same temperature as for laminates containing plastic, the time required for heat sealing will be longer, reducing productivity.

To increase productivity, it is possible to reduce the thickness of the paper. However, if the thickness of the paper is reduced, the weight ratio of paper in the laminate will be small, and the paper classification for recycling will not be maintained.

The present invention was made with these points in mind, and aims to increase the productivity of packaging containers while maintaining paper classification for recycling.

The present invention relates to a laminate comprising, in order from the outside to the inside, at least a paper base layer, an adhesive layer, a vapor deposition layer, and a sealant layer,
the sealant layer includes a first surface located on an inner side and a second surface located opposite the first surface;
the sealant layer comprises a polyolefin resin layer constituting the first surface,
The polyolefin resin layer contains polypropylene, which is an ethylene-propylene random copolymer, as a main component and also contains polyethylene,
The polyolefin resin layer is a laminate having a DSC main peak located at 145° C. or lower.

In the laminate of the present invention, the adhesive layer may be an adhesive layer.

In the laminate of the present invention, the adhesive layer may contain a cured product of a composition containing a polyester polyol and an isocyanate compound.

In the laminate of the present invention, the polyolefin resin layer may have a DSC sub-peak located at a lower temperature than the DSC main peak, and the difference in temperature between the DSC main peak and the DSC sub-peak may be 15°C or less.

In the laminate of the present invention, the sealant layer may include a primer layer constituting the second surface, and the primer layer may be in contact with the deposition layer.

In the laminate of the present invention, the primer layer may contain a urethane resin or a cellulose resin.

In the laminate of the present invention, the vapor deposition layer may include an aluminum vapor deposition layer.

In the laminate of the present invention, the paper base layer may have a basis weight of 20 g/m ² or more and 120 g/m ² or less.

In the laminate of the present invention, the weight ratio of the paper base layer in the laminate may be greater than 50%.

The present invention is a packaging container having the laminate described above.

The laminate of the present invention can increase the productivity of packaging containers while maintaining paper classification for recycling.

FIG. 2 is a cross-sectional view showing an example of a laminate. FIG. 2 is a cross-sectional view showing an example of a laminate. FIG. 2 is a cross-sectional view showing an example of a laminate. FIG. 1 is a cross-sectional view showing an example of a barrier film. FIG. 2 is a diagram showing an example of a DSC curve of a barrier film. FIG. 1 is a diagram showing an example of a method for producing a test piece. FIG. 2 is a cross-sectional view of a test piece. FIG. 2 is a diagram showing a method for measuring seal strength. FIG. 2 is a diagram showing a method for measuring seal strength. FIG. 1 is a diagram showing an example of a packaging container. FIG. 1 is a diagram showing an example of a method for producing a test piece. FIG. 1 shows the DSC curve of the barrier film of Example P1. FIG. 2 shows the DSC curve of the barrier film of Example P2. FIG. 1 is a diagram showing the evaluation results of examples and comparative examples. FIG. 4 is a diagram showing the measurement results of the seal strength in the examples and the comparative examples.

The following describes an embodiment of the present invention. In the drawings accompanying this specification, the scale and aspect ratios have been appropriately altered and exaggerated from those of the actual product for the sake of ease of illustration and understanding.

In addition, terms used in this specification that specify shapes, geometric conditions, and their degrees, such as "orthogonal" and "same," as well as values of length and angle, are not limited to their strict meanings, but are interpreted to include the range within which similar functions can be expected.

In this specification, when two or more upper limit candidates and two or more lower limit candidates are given for a certain parameter, the numerical range of the parameter may be constructed by combining any one of the upper limit candidates with any one of the lower limit candidates. For example, consider a case where "Parameter B may be, for example, A1 or more and may be A2 or more. Parameter B may be, for example, A3 or less and may be A4 or less." In this case, the numerical range of parameter B may be A1 or more and A3 or less, A1 or more and A4 or less, A2 or more and A3 or less, or A2 or more and A4 or less.

(Laminate)
FIG. 1 is a cross-sectional view showing an example of a laminate 50 according to the present embodiment. The laminate 50 includes an inner surface 50x and an outer surface 50y. The inner surface 50x is a surface that is joined by a sheet seal. The outer surface 50y is located opposite the inner surface 50x. The laminate 50 includes, in order from the outside to the inside, a paper base layer 40, an adhesive layer 45, and a barrier film 10. In the example shown in FIG. 1, the paper base layer 40 constitutes the outer surface 50y.

The barrier film 10 comprises a sealant layer 20 and a deposition layer 30. The sealant layer 20 includes a first surface 20x and a second surface 20y. The first surface 20x is located on the inner side. In the example shown in FIG. 1, the first surface 20x constitutes the inner surface 50x. The second surface 20y is located on the opposite side to the first surface 20x. The deposition layer 30 is located on the second surface 20y. The sealant layer 20 includes a polyolefin resin layer 21.

The layer structure of the laminate 50 in the example shown in FIG. 1 is expressed as follows, from the outside to the inside.
Paper base layer/adhesive layer/vapor deposition layer/polyolefin resin layer "/" represents the boundary between two adjacent layers.

Figure 2 is a cross-sectional view showing another example of the laminate 50 according to the present embodiment. The laminate 50 may include a printed layer 41 located on the outside of the paper base layer 40. The printed layer 41 may form the outer surface 50y.

The layer structure of the laminate 50 in the example shown in FIG. 2 is expressed as follows, from the outside to the inside.
Printing layer/paper base layer/adhesive layer/vapor deposition layer/polyolefin resin layer

Figure 3 is a cross-sectional view showing another example of the laminate 50 according to the present embodiment. The sealant layer 20 may include a primer layer 22 located on the outer side of the polyolefin resin layer 21. The primer layer 22 may constitute the second surface 20y. The primer layer 22 may be in contact with the vapor deposition layer 30.

The layer structure of the laminate 50 in the example shown in FIG. 3 is expressed as follows, from the outside to the inside.
Paper base layer / adhesive layer / vapor deposition layer / primer layer / polyolefin resin layer

As long as the laminate 50 has, in order from the outside to the inside, at least a paper base layer 40, an adhesive layer 45, a vapor deposition layer 30, and a sealant layer 20, the layer configuration of the laminate 50 is arbitrary. The laminate 50 according to this embodiment may have a layer configuration other than the layer configurations shown in Figures 1 to 3. For example, the laminate 50 may have a primer layer 22 shown in Figure 3 in addition to the layer configuration shown in Figure 2.

The thickness of the laminate 50 is, for example, 50 μm or more, and may be 60 μm or more, or 80 μm or more. The thickness of the laminate 50 is, for example, 200 μm or less, and may be 150 μm or less, or 100 μm or less.

Each layer of the laminate 50 will now be described in detail.

[Paper base layer]
The paper substrate layer 40 is a layer that functions as a substrate. The paper substrate layer 40 includes paper. The paper substrate layer 40 imparts strength to the laminate 50. The paper is, for example, kraft paper, fine paper, coated paper, or the like. The kraft paper may be unbleached kraft. That is, the color of the kraft paper may be brown.

The basis weight of the paper base layer 40 is set so that the weight ratio of the paper base layer 40 in the laminate 50 is greater than 50%. This allows the classification of the laminate 50 and the packaging container in recycling to be paper classification. The basis weight of the paper base layer 40 is, for example, 20 g/m ² or more, may be 30 g/m ² or more, or may be 40 g/m ² or more. The basis weight of the paper base layer 40 is, for example, 120 g/m ² or less, may be 100 g/m ² or less, or may be 80 g/m ² or less.

The weight ratio of the paper base layer 40 in the laminate 50 may be 51% or more, or 60% or more. The weight ratio of the paper base layer 40 in the laminate 50 may be 95% or less, 90% or less, or 80% or less.

[Sealant Layer]
The sealant layer 20 is made of, for example, a sealant film. The sealant film is, for example, a film produced by molding the material constituting the polyolefin resin layer 21 by a melt extrusion method. The sealant film is preferably an unstretched film. The term "unstretched" is a concept that includes not only a film that is not stretched at all, but also a film that is slightly stretched due to the tension applied during film formation.

The polyolefin resin layer 21 contains polypropylene as a main component and also contains polyethylene. "Main component" means that the weight ratio of polypropylene in the polyolefin resin layer 21 is 51% or more. The weight ratio of polypropylene in the polyolefin resin layer 21 may be 60% or more, 70% or more, 80% or more, or 90% or more.

The polypropylene of the polyolefin resin layer 21 is, for example, a random copolymer. The random copolymer is a random copolymer containing propylene and an α-olefin other than propylene. For example, the random copolymer contains ethylene, butene-1, 4-methyl-1-pentene, etc. in addition to propylene. For example, the random copolymer includes an ethylene-propylene random copolymer. The structural formula of an ethylene-propylene random copolymer is shown below. In the following formula, m and n are integers of 1 or more. The random copolymer may include a terpolymer.

The polyolefin resin layer 21 may contain biomass-derived polypropylene. The polyolefin resin layer 21 may contain mechanically recycled or chemically recycled polypropylene.

The polyethylene of the polyolefin resin layer 21 may be a homopolymer of ethylene or a copolymer of ethylene and an α-olefin (hereinafter also referred to as an ethylene-α-olefin copolymer). The content of α-olefin in the ethylene-α-olefin copolymer is preferably 5 mol% or less.

The weight ratio of polyethylene in the polyolefin resin layer 21 may be 1% or more, 5% or more, or 10% or more. The weight ratio of polyethylene in the polyolefin resin layer 21 may be 30% or less, 25% or less, or 20% or less.

Examples of ethylene homopolymers include high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE).

High density polyethylene is polyethylene having a density of 0.942 g/cm3 or ^more . Medium density polyethylene is polyethylene having a density of 0.930 g/ ^cm3 or more and less than 0.942 g/ ^cm3 . Low density polyethylene is polyethylene having a density of 0.910 g/ ^cm3 or more and less than 0.930 g/ ^cm3 .

The density of resins, layers, films, etc. is measured in accordance with JIS K7112:1999, Method B (pycnometer method) or Method D (density gradient tube method). Method B or Method D is selected appropriately depending on the shape and mass of the test piece to be measured. When Method D is selected, the measurement temperature (liquid temperature) is 23°C.

An example of the ethylene-α-olefin copolymer is linear polyethylene. Linear polyethylene is a copolymer of ethylene and an α-olefin polymerized using a multi-site catalyst, such as a Ziegler-Natta catalyst, or a single-site catalyst, such as a metallocene catalyst. Linear polyethylene is distinguished from a homopolymer of ethylene. The α-olefin, which is a monomer of linear polyethylene, has 3 or more carbon atoms. Examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-nonene, 4-methylpentene, 3,3-dimethylbutene, and mixtures thereof. Linear polyethylene having a density of less than 0.930 g/cm ³ may be referred to as linear low density polyethylene (LLDPE).

The polyolefin resin layer 21 may be composed of a single layer containing polypropylene and polyethylene. The polyolefin resin layer 21 may have two or more layers containing polypropylene. In this case, at least one of the two or more layers contains polypropylene and polyethylene. The film constituting the polyolefin resin layer 21 containing two or more layers is produced, for example, by forming the materials constituting the polyolefin resin layer 21 by a coextrusion method.

Figure 4 is a cross-sectional view showing an example of a barrier film 10 including a polyolefin resin layer 21. The polyolefin resin layer 21 may include a first layer 21a, a second layer 21b, and a third layer 21c arranged from the inside to the outside. The first layer 21a constitutes the first surface 20x. Although not shown, the barrier film 10 may also include a primer layer 22 located between the third layer 21c and the deposition layer 30.

The first layer 21a, the second layer 21b, and the third layer 21c include polypropylene. The first layer 21a may include polypropylene and polyethylene. For example, the first layer 21a may include polypropylene and HDPE.

The weight ratio of polyethylene in the first layer 21a may be higher than the weight ratio of polyethylene in the second layer 21b and the third layer 21c. The second layer 21b and the third layer 21c may not contain polyethylene. In this way, the distribution of polyethylene in the polyolefin resin layer 21 may be biased toward the first surface 20x.

The thickness of the polyolefin resin layer 21 is, for example, 20 μm or more, may be 25 μm or more, or may be 30 μm or more. The thickness of the polyolefin resin layer 21 is, for example, 60 μm or less, may be 50 μm or less, or may be 40 μm or less.

The polyolefin resin layer 21 may have a melting point of, for example, 145°C or less. This makes it easier for the polyolefin resin layer 21 to melt during heat sealing. Therefore, even if the laminate 50 includes a paper base layer 40, the time required for heat sealing can be prevented from becoming long. Therefore, it is possible to increase the productivity of packaging containers while maintaining paper classification for recycling.

The melting point is calculated by analyzing the polyolefin resin layer 21 using a differential scanning calorimeter in accordance with JIS K7121:2012. In the analysis, a sample containing the polyolefin resin layer 21 is taken. The sample may be taken from the laminate 50, from the barrier film 10, or from the sealant film that constitutes the sealant layer 20. The weight of the sample is about 5 mg.

In the analysis, the sample is placed in an aluminum cell. Then, in a nitrogen atmosphere, the sample is heated from 20°C to the holding temperature at a heating rate of 10°C/min. The holding temperature is a temperature sufficiently higher than the melting point, for example, 200°C. Next, the sample is heated at the holding temperature for 10 minutes. After that, the sample is cooled from the holding temperature to 20°C at a heating rate of 10°C/min. This heating, holding, and cooling process is repeated once more. Figure 5 shows an example of a DCS curve observed during the second heating. As a differential scanning calorimeter, for example, a thermal analyzer TA7000 series manufactured by Hitachi High-Tech Science Corporation can be used.

As shown in FIG. 5, the DCS curve of the polyolefin resin layer 21 includes a DSC main peak P1 located at a first temperature T1. The DSC main peak P1 is the maximum endothermic peak. The first temperature T1 is, for example, 145°C or less, may be 143°C or less, or may be 141°C or less. The first temperature T1 is, for example, 130°C or more, may be 132°C or more, or may be 134°C or more.

As shown in FIG. 5, the DCS curve of the polyolefin resin layer 21 may include a DSC subpeak P2 located at a second temperature T2. The DSC subpeak P2 is, for example, the second largest endothermic peak. The second temperature T2 is lower than the first temperature T1. That is, the DSC subpeak P2 is located at a lower temperature than the DSC main peak P1. The second temperature T2 is, for example, 135°C or lower, may be 133°C or lower, or may be 131°C or lower. The second temperature T2 is, for example, 120°C or higher, may be 122°C or higher, or may be 124°C or higher.

The difference between the first temperature T1 and the second temperature T2 is, for example, 15°C or less, and may be 13°C or less, or 11°C or less. The difference between the first temperature T1 and the second temperature T2 is, for example, 5°C or more, and may be 7°C or more, or 9°C or more.

As described above, the sealant layer 20 may include a primer layer 22 constituting the second surface 20y. The primer layer 22 can increase the adhesion of the deposition layer 30 to the sealant layer 20. The primer layer 22 includes, for example, a urethane-based resin, a cellulose-based resin, etc. The primer layer 22 may include one of these resins, or may include two or more of them.

The primer layer 22 is formed, for example, by applying a solution containing the material of the primer layer 22 to the film constituting the polyolefin resin layer 21. The thickness of the primer layer 22 is, for example, 0.1 μm or more, and may be 0.5 μm or more, or 1.0 μm or more. The thickness of the primer layer 22 is, for example, 5.0 μm or less, and may be 4.0 μm or less, or 3.0 μm or less.

[Vapour-deposited layer]
The deposition layer 30 includes a metal layer or an inorganic oxide layer. The deposition layer 30 is difficult to pass gases such as oxygen and water vapor. Therefore, the barrier film 10 and the laminate described later can have barrier properties such as oxygen barrier property and water vapor barrier property. This can prevent the weight of the contents from decreasing in a packaging container made of the laminate. In addition, when a metal layer is used, it can prevent light from passing through the laminate and reaching the contents. This can prevent oxidation of components of the contents such as oil.

The metal layer may include a metal such as aluminum. For example, the metal layer may include a layer of aluminum vapor-deposited on the second surface 20y of the sealant layer 20.

The inorganic oxide layer may contain inorganic oxides such as aluminum oxide (alumina), silicon oxide (silica), magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, barium oxide, and silicon carbide oxide (carbon-containing silicon oxide). Preferably, the inorganic oxide layer contains silica, silicon carbide oxide, or alumina.

The thickness of the deposition layer 30 is, for example, 1 nm or more, and may be 5 nm or more, or 10 nm or more. This can further improve the barrier properties of the barrier film 10. The thickness of the deposition layer 30 may be 150 nm or less, 100 nm or less, or 80 nm or less. This can prevent defects such as cracks from occurring in the deposition layer 30. In addition, the recyclability of the laminate and the packaging container can be improved.

The deposition layer 30 may consist of a single layer, or may include two or more layers. A single layer is a layer formed by one deposition process. Two or more layers are formed by two or more deposition processes. The materials constituting the two or more layers may be the same or different. The methods of forming the two or more layers may be the same or different.

[Adhesive layer]
The adhesive layer 45 is a layer that bonds the substrate including the paper substrate layer 40 to the barrier film 10. The adhesive layer 45 may be an adhesive agent layer or an adhesive resin layer.

The adhesive layer includes at least one adhesive. The adhesive may be a one-component curing type, a two-component curing type, or a non-curing type adhesive. The adhesive may be a solvent-free adhesive or a solvent-based adhesive. From the viewpoint of environmental load, a solvent-free adhesive is preferred.
Examples of the solventless adhesive include polyether adhesives, polyester adhesives, silicone adhesives, epoxy adhesives, and urethane adhesives.
Examples of solvent-based adhesives include rubber-based adhesives, vinyl-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and olefin-based adhesives.

In the process of manufacturing a packaging container using the laminate 50 having the deposition layer 30, a bending load may be applied to the laminate 50. In this case, damage such as cracks may occur in the deposition layer 30. Preferably, the adhesive is configured to suppress the occurrence of damage or to repair the damage. For example, the adhesive includes a cured product of a composition including a polyester polyol and an isocyanate compound. This can improve the barrier properties of the laminate 50, such as the oxygen barrier property and water vapor barrier property.

The glass transition temperature of the cured product of the composition containing the polyester polyol and the isocyanate compound is, for example, -30°C or higher, or may be 0°C or higher, or 25°C or higher. This can improve the oxygen barrier property, water vapor barrier property, and laminate strength of the laminate 50. The glass transition temperature is calculated by differential scanning calorimetry (DSC) in accordance with JIS K 7121:2012.

Polyester polyols have two or more hydroxyl groups as functional groups in one molecule. Also, isocyanate compounds have two or more isocyanate groups as functional groups in one molecule. Polyester polyols have, for example, a polyester structure or a polyester polyurethane structure as the main skeleton.

A specific example of a composition (adhesive) containing polyester polyol and an isocyanate compound is the PASLIM series manufactured by DIC Corporation.

The composition containing the polyester polyol and the isocyanate compound may further contain a phosphate ester, a plate-like inorganic compound, a coupling agent, cyclodextrin and/or a derivative thereof, etc.

Examples of polyester polyols having two or more hydroxyl groups in one molecule as functional groups include the following [First Example] to [Third Example].
[Example 1] Polyester polyol obtained by polycondensation of ortho-oriented polyvalent carboxylic acid or its anhydride with polyhydric alcohol. [Example 2] Polyester polyol having a glycerol skeleton. [Example 3] Polyester polyol having an isocyanuric ring.

The polyester polyol according to the first example is a polycondensate obtained by polycondensing a polyvalent carboxylic acid component containing at least one kind of orthophthalic acid and its anhydride, and a polyhydric alcohol component.
In particular, polyester polyols in which the content of orthophthalic acid or its anhydride relative to the total amount of polyvalent carboxylic acids is 70 to 100% by mass are preferred.

The polyester polyol according to the first example essentially contains orthophthalic acid and its anhydride as the polycarboxylic acid component. Other polycarboxylic acid components may be copolymerized within a range that does not impair the effect of the present embodiment.
Examples of the other polyvalent carboxylic acid component include aliphatic polyvalent carboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid; unsaturated bond-containing polyvalent carboxylic acids such as maleic anhydride, maleic acid, and fumaric acid; alicyclic polyvalent carboxylic acids such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; aromatic polyvalent carboxylic acids such as terephthalic acid, isophthalic acid, pyromellitic acid, trimellitic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, anhydrides of these dicarboxylic acids, and ester-forming derivatives of these dicarboxylic acids; and polybasic acids such as p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids. Of these, succinic acid, 1,3-cyclopentanedicarboxylic acid, and isophthalic acid are preferred.
Two or more of the above other polyvalent carboxylic acids may be used.

The polyhydric alcohol component is, for example, an aliphatic polyhydric alcohol, an aromatic polyhydric alcohol, or the like.
Examples of the aliphatic polyhydric alcohol include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, cyclohexanedimethanol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol.
Examples of aromatic polyhydric alcohols include hydroquinone, resorcinol, catechol, naphthalenediol, biphenol, bisphenol A, bisphenol F, tetramethylbiphenol, ethylene oxide extension products thereof, and hydrated aliphatic compounds thereof.
The polyhydric alcohol component may contain at least one selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanedimethanol.

The polyester polyol according to the second example is, for example, a polyester polyol having a glycerol skeleton represented by general formula (1).
In general formula (1), R ₁ , R ₂ and R ₃ each independently represent H (hydrogen atom) or a group represented by the following general formula (2).

In formula (2), n represents an integer of 1 to 5, X represents an arylene group selected from the group consisting of 1,2-phenylene groups, 1,2-naphthylene groups, 2,3-naphthylene groups, 2,3-anthraquinonediyl groups, and 2,3-anthracenediyl groups, which may have a substituent, and Y represents an alkylene group having 2 to 6 carbon atoms), with the proviso that at least one of R ₁ , R ₂ , and R ₃ represents a group represented by general formula (2).

In general formula (1), at least one of R ₁ , R ₂ and R ₃ must be a group represented by general formula (2). In particular, it is preferable that all of R ₁ , R ₂ and R ₃ are groups represented by general formula (2).

The polyester polyol may contain a mixture of two or more _{of the following compounds: a compound in which any one of R 1, R 2, and R 3 is a group represented} by general formula (2); a compound in which any two of _{R 1} , R ₂ , and R ₃ are groups represented by general formula (2); and a compound in which all of R 1, R 2, and R 3 are groups represented by general formula (2).

X represents an arylene group which may have a substituent and is selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group.
When X is substituted with a substituent, it may be substituted with one or more substituents. The substituent is bonded to any carbon atom on X that is different from the free group. Examples of the substituent include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, and a naphthyl group.

In general formula (2), Y represents an alkylene group having 2 to 6 carbon atoms, such as an ethylene group, a propylene group, a butylene group, a neopentylene group, a 1,5-pentylene group, a 3-methyl-1,5-pentylene group, a 1,6-hexylene group, a methylpentylene group, or a dimethylbutylene group. Of these, a propylene group or an ethylene group is preferable, and an ethylene group is most preferable.

The polyester resin compound having a glycerol skeleton represented by general formula (1) is synthesized, for example, by reacting glycerol with an aromatic polycarboxylic acid or its anhydride in which a carboxylic acid is substituted at the ortho position, and a polyhydric alcohol component as essential components.

Examples of aromatic polycarboxylic acids or anhydrides in which a carboxylic acid is substituted at the ortho position include orthophthalic acid or anhydride, naphthalene 2,3-dicarboxylic acid or anhydride, naphthalene 1,2-dicarboxylic acid or anhydride, anthraquinone 2,3-dicarboxylic acid or anhydride, and 2,3-anthracene carboxylic acid or anhydride.
These compounds may have a substituent at any carbon atom of the aromatic ring, such as a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, or a naphthyl group.

The polyhydric alcohol component is, for example, an alkylene diol having 2 to 6 carbon atoms. For example, diols such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, and dimethylbutanediol are used.

The polyester polyol according to the third example is a polyester polyol having an isocyanuric ring represented by the following general formula (3).
In formula (3), R ₁ , R ₂ and R ₃ each independently represent "--(CH ₂ )n1-OH (wherein n1 represents an integer of 2 to 4)" or a structure represented by formula (4).

In the general formula (4), n2 represents an integer of 2 to 4, and n3 represents an integer of 1 to 5. X represents an arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group, which may have a substituent. Y represents an alkylene group having 2 to 6 carbon atoms). However, at least one of R ₁ , R ₂ , and R ₃ is a group represented by the general formula (4).

In the general formula (3), the alkylene group represented by -(CH ₂ )n1- may be linear or branched. Among these, n1 is preferably 2 or 3, and most preferably 2.

In general formula (4), n2 represents an integer from 2 to 4, and n3 represents an integer from 1 to 5. X represents an arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group, and may have a substituent.

When X is substituted with a substituent, it may be substituted with one or more substituents. The substituent is bonded to any carbon atom on X that is different from the free group. Examples of the substituent include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, and a naphthyl group.
The substituent for X is preferably a hydroxyl group, a cyano group, a nitro group, an amino group, a phthalimido group, a carbamoyl group, an N-ethylcarbamoyl group, or a phenyl group, and most preferably a hydroxyl group, a phenoxy group, a cyano group, a nitro group, a phthalimido group, or a phenyl group.

In general formula (4), Y represents an alkylene group having 2 to 6 carbon atoms, such as an ethylene group, a propylene group, a butylene group, a neopentylene group, a 1,5-pentylene group, a 3-methyl-1,5-pentylene group, a 1,6-hexylene group, a methylpentylene group, or a dimethylbutylene group. Of these, a propylene group or an ethylene group is preferable, and an ethylene group is most preferable.

In formula (3), at least one of R ₁ , R ₂ and R ₃ is a group represented by formula (4). In particular, it is preferred that all of R ₁ , R ₂ and R ₃ are groups represented by formula (4).

The polyester polyol may contain a mixture of two or more _{of the following compounds: a compound in which any one of R 1, R 2, and R 3 is a group represented} by general formula (4); a compound in which any two of _{R 1} , R ₂ , and R ₃ are groups represented by general formula (4); and a compound in which all of R 1, R 2, and R 3 are groups represented by general formula (4).

The polyester polyol having an isocyanuric ring represented by the general formula (3) is synthesized by reacting a triol having an isocyanuric ring, an aromatic polycarboxylic acid or its anhydride in which a carboxylic acid is substituted at the ortho position, and a polyhydric alcohol component as essential components.

Triols having an isocyanuric ring include, for example, alkylene oxide adducts of isocyanuric acid, such as 1,3,5-tris(2-hydroxyethyl)isocyanuric acid and 1,3,5-tris(2-hydroxypropyl)isocyanuric acid.

Examples of aromatic polycarboxylic acids or anhydrides in which the carboxylic acid is substituted at the ortho position include orthophthalic acid or anhydride, naphthalene 2,3-dicarboxylic acid or anhydride, naphthalene 1,2-dicarboxylic acid or anhydride, anthraquinone 2,3-dicarboxylic acid or anhydride, and 2,3-anthracene carboxylic acid or anhydride. These compounds may have a substituent on any carbon atom of the aromatic ring.

Examples of the substituent include chloro, bromo, methyl, ethyl, i-propyl, hydroxyl, methoxy, ethoxy, phenoxy, methylthio, phenylthio, cyano, nitro, amino, phthalimido, carboxyl, carbamoyl, N-ethylcarbamoyl, phenyl, and naphthyl groups.

The polyhydric alcohol component is, for example, an alkylene diol having 2 to 6 carbon atoms, such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, and dimethylbutanediol.
Among these, polyester polyol compounds having an isocyanuric ring, which use 1,3,5-tris(2-hydroxyethyl)isocyanuric acid or 1,3,5-tris(2-hydroxypropyl)isocyanuric acid as the triol compound having an isocyanuric ring, orthophthalic anhydride as the aromatic polycarboxylic acid or its anhydride in which the carboxylic acid is substituted at the ortho position, and ethylene glycol as the polyhydric alcohol, are particularly excellent in oxygen barrier properties and adhesive properties and are therefore preferred.

Isocyanuric rings are highly polar and trifunctional, and can increase the polarity of the entire system and increase the crosslink density. From this perspective, it is preferable for the adhesive resin to contain 5% by mass or more of isocyanuric rings based on the total solid content.

The isocyanate compound has two or more isocyanate groups in the molecule.
The isocyanate compound may be an aromatic compound, an aliphatic compound, a low molecular weight compound, or a high molecular weight compound.
The isocyanate compound may be a blocked isocyanate compound obtained by addition reaction using a known isocyanate blocking agent by a known appropriate method.
Among these, from the viewpoints of adhesiveness and retort resistance, polyisocyanate compounds having three or more isocyanate groups are preferred, and from the viewpoints of oxygen barrier property and water vapor barrier property, aromatic compounds are preferred.

Examples of the isocyanate compound include tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, metaxylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and trimers of these isocyanate compounds, as well as adducts, biurets, and allophanates obtained by reacting these isocyanate compounds with low-molecular-weight active hydrogen compounds or their alkylene oxide adducts, or high-molecular-weight active hydrogen compounds.
Examples of low molecular weight active hydrogen compounds include ethylene glycol, propylene glycol, metaxylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, metaxylylenediamine, etc. Examples of molecular weight active hydrogen compounds include polymeric active hydrogen compounds such as various polyester resins, polyether polyols, and polyamides.

The adhesive layer formed of the cured product of the composition containing the polyester polyol and the isocyanate compound may contain a phosphoric acid-modified compound. For example, the adhesive layer may contain a compound represented by the following general formula (5) or (6).
In general formula (5), R ₁ , R ₂ and R ₃ are groups selected from a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a (meth)acryloyl group, a phenyl group which may have a substituent, and an alkyl group having 1 to 4 carbon atoms which has a (meth)acryloyloxy group. At least one of _{R 1} , R ₂ and R ₃ is a hydrogen atom. n represents an integer of 1 to 4.
R ₄ and R ₅ are groups selected from a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a (meth)acryloyl group, a phenyl group which may have a substituent, and an alkyl group having 1 to 4 carbon atoms and having a (meth)acryloyloxy group. n represents an integer of 1 to 4, x represents an integer of 0 to 30, and y represents an integer of 0 to 30. Either x or y is greater than 0.

Examples of phosphoric acid-modified compounds include phosphoric acid, pyrophosphoric acid, triphosphoric acid, methyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, dibutyl phosphate, 2-ethylhexyl acid phosphate, bis(2-ethylhexyl) phosphate, isododecyl acid phosphate, butoxyethyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, 2-hydroxyethyl methacrylate acid phosphate, and polyoxyethylene alkyl ether phosphate. The adhesive layer may contain one or more of these.

The content of the phosphoric acid-modified compound in the adhesive layer containing the polyester polyol and the isocyanate compound is, for example, 0.005% by mass, and may be 0.01% by mass or more. The content of the phosphoric acid-modified compound is, for example, 10% by mass or less, and may be 1% by mass or less.
By setting the content of the phosphate-modified compound to 0.005% by mass or more, the oxygen barrier property and water vapor barrier property can be improved, and by setting the content of the phosphate-modified compound to 10% by mass or less, the adhesiveness of the adhesive layer can be improved.

The adhesive layer containing polyester polyol and an isocyanate compound may contain a plate-like inorganic compound. This can improve the oxygen barrier property, water vapor barrier property, and adhesiveness of the adhesive layer. In addition, the flex resistance of the laminate 50 can be improved.
Examples of the plate-like inorganic compounds include kaolinite-serpentine group clay minerals (such as halloysite, kaolinite, enderite, dickite, nacrite, antigorite, and chrysotile) and pyrophyllite-talc group (such as pyrophyllite, talc, and keroli).

The coupling agent is, for example, a silane-based coupling agent, a titanium-based coupling agent, or an aluminum-based coupling agent represented by the following general formula (7). These coupling agents may be used alone or in combination of two or more kinds.

Examples of silane coupling agents include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxytrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, N-β( aminoethyl) gamma-aminopropylmethyldimethoxysilane, N-β(aminoethyl) gamma-aminopropyltrimethoxysilane, N-β(aminoethyl) gamma-aminopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, N-phenyl-gamma-aminopropyltrimethoxysilane, gamma-chloropropyltrimethoxysilane, gamma-mercaptopropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-triethoxysilyl-N-(1,3-dimethylbutylidene).

Examples of titanium-based coupling agents include isopropyl triisostearoyl titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, tetraoctyl bis(didodecyl phosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, bis(dioctyl pyrophosphate)oxyacetate titanate, bis(dioctyl pyrophosphate)ethylene titanate, isopropyl trioctyl nor titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl isostearoyl diacryl titanate, diisostearoyl ethylene titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumyl phenyl titanate, and dicumyl phenyl oxyacetate titanate.

Examples of aluminum-based coupling agents include acetoalkoxyaluminum diisopropylate, diisopropoxyaluminum ethyl acetoacetate, diisopropoxyaluminum monomethacrylate, isopropoxyaluminum alkyl acetoacetate mono(dioctyl phosphate), aluminum 2-ethylhexanoate oxide trimer, aluminum stearate oxide trimer, and alkyl acetoacetate aluminum oxide trimer.

The adhesive layer made of the composition containing polyester polyol and an isocyanate compound may contain cyclodextrin and/or a derivative thereof. This can increase the adhesiveness of the adhesive layer. In addition, the flex resistance of the laminate 50 can be increased.
Examples of cyclodextrin and/or its derivatives include cyclodextrin, alkylated cyclodextrin, acetylated cyclodextrin, hydroxyalkylated cyclodextrin, and other cyclodextrins in which the hydrogen atoms of the hydroxyl groups of the glucose units of cyclodextrin are substituted with other functional groups. Branched cyclic dextrins may also be used. The cyclodextrin skeleton in cyclodextrin and cyclodextrin derivatives may be any of α-cyclodextrin consisting of six glucose units, β-cyclodextrin consisting of seven glucose units, and γ-cyclodextrin consisting of eight glucose units.
These compounds may be used alone or in combination of two or more kinds. These cyclodextrins and/or their derivatives may be collectively called dextrin compounds.

From the viewpoint of compatibility and dispersibility in the adhesive layer containing a polyester polyol and an isocyanate compound, it is preferable to use a cyclodextrin derivative as the cyclodextrin compound.
From the viewpoint of the polarity of the various resins, the degree of substitution may be, for example, 0.1 or more/glucose or 0.3 or more/glucose, and may be, for example, 14 or less/glucose or 8 or less/glucose.

Examples of alkylated cyclodextrins include methyl-α-cyclodextrin, methyl-β-cyclodextrin, and methyl-γ-cyclodextrin. These compounds may be used alone or in combination of two or more.

Examples of acetylated cyclodextrins include monoacetyl-α-cyclodextrin, monoacetyl-β-cyclodextrin, and monoacetyl-γ-cyclodextrin. These compounds may be used alone or in combination of two or more.

Examples of hydroxyalkylated cyclodextrins include hydroxypropyl-α-cyclodextrin, hydroxypropyl-β-cyclodextrin, and hydroxypropyl-γ-cyclodextrin. These compounds may be used alone or in combination of two or more.

The thickness of the adhesive layer is, for example, 0.5 μm or more, may be 0.8 μm or more, or may be 1.0 μm or more. This can increase the adhesiveness of the adhesive layer. Also, the bending resistance of the laminate 50 can be increased.
The thickness of the adhesive layer is, for example, 6 μm or less, may be 5 μm or less, or may be 4.5 μm or less, which can improve the processability of the laminate 50. In addition, the recyclability of the laminate 50 and the packaging container can be improved.

The adhesive layer is formed, for example, by a dry lamination method in which an adhesive is used to bond the substrate and the barrier film 10. For example, the adhesive layer is formed by applying an adhesive to one surface of the substrate or the barrier film 10 and drying it. Examples of application methods include direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fontaine, and transfer roll coating.

Next, the adhesive resin layer will be described. The adhesive resin layer includes a thermoplastic resin. The adhesive resin layer is formed by, for example, a melt extrusion lamination method or a sand lamination method. The thermoplastic resin is, for example, a polyolefin resin, a cyclic polyolefin resin, or a copolymer resin, a modified resin, or a mixture containing these resins as the main component.
Examples of polyolefin resins include low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), polypropylene (PP), ethylene-α-olefin copolymers polymerized using a metallocene catalyst, random or block copolymers of ethylene and polypropylene, ethylene-vinyl acetate copolymers (EVA), ethylene-acrylic acid copolymers (EAA), ethylene-ethyl acrylate copolymers (EEA), ethylene-methacrylic acid copolymers (EMAA), ethylene-methyl methacrylate copolymers (EMMA), ethylene-maleic acid copolymers, and ionomer resins. Acid-modified polyolefin resins obtained by modifying polyolefin resins with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid may also be used. Resins obtained by graft-polymerizing or copolymerizing unsaturated carboxylic acids, unsaturated carboxylic anhydrides, and ester monomers with polyolefin resins may also be used. One of these materials may be used alone, or two or more of them may be used in combination.
Examples of the cyclic polyolefin resin include cyclic polyolefins such as ethylene-propylene copolymers, polymethylpentene, polybutene, polynorbornene, etc. One of these materials may be used alone, or two or more of them may be used in combination.

The thickness of the adhesive resin layer is, for example, 5 μm or more, may be 10 μm or more, or may be 15 μm or more. The thickness of the adhesive resin layer is, for example, 50 μm or less, may be 40 μm or less, or may be 30 μm or less.

[Printing layer]
The printed layer 41 has a printed pattern such as letters, numbers, pictures, figures, symbols, and patterns. The printed layer 41 is provided for decoration, display of contents, display of expiration date, display of manufacturer, seller, etc., and for providing aesthetics. The printed layer 41 may be provided on the entire surface of the paper base layer 40, or may be provided on only a part of it. The printed layer 41 may contain a pigment or a dye.

The thickness of the printed layer 41 is, for example, 0.5 μm or more, and may be 0.8 μm or more, or 1.0 μm or more. The thickness of the printed layer 41 is, for example, 6 μm or less, and may be 5 μm or less, or 4.5 μm or less.

(Method for manufacturing laminate)
Next, a method for producing the barrier film 10 will be described.

First, a sealant film including a polyolefin resin layer 21 is prepared. For example, the material constituting the polyolefin resin layer 21 is formed by a melt extrusion method. When the polyolefin resin layer 21 has two or more layers, the material constituting the polyolefin resin layer 21 may be formed by a co-extrusion method. A primer layer 22 may be formed on the obtained film.

Next, a deposition layer 30 is formed on the sealant film. This results in a barrier film 10 having a sealant layer 20 and a deposition layer 30.

The deposition layer 30 can be formed by a known method. For example, physical vapor deposition methods (PVD methods) such as vacuum deposition, sputtering, and ion plating, as well as chemical vapor deposition methods (CVD methods) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition can be used.

A substrate including a paper substrate layer 40 is also prepared. The substrate may include a printing layer 41 located on the paper substrate layer 40.

Next, a lamination process is carried out in which the substrate and the barrier film 10 are laminated via the adhesive layer 45.

When the adhesive layer 45 is an adhesive layer, first, the adhesive is applied to either the substrate or the barrier film 10. After the adhesive has dried, the substrate and the barrier film 10 are laminated by a dry lamination method.

When the adhesive layer 45 is an adhesive resin layer, for example, the substrate and the barrier film 10 are laminated by a sand lamination method. For example, the material of the adhesive resin layer in a molten state is extruded between the substrate and the barrier film 10. This bonds the barrier film 10 to the substrate.

(Effect of the laminate)
In this embodiment, the polyolefin resin layer 21 of the sealant layer 20 contains polyethylene in addition to polypropylene, which is the main component. Therefore, the polyolefin resin layer 21 can have a DSC main peak P1 located at 145°C or lower. Therefore, the first surface 20x of the sealant layer 20 is easily melted during heat sealing. As a result, even when the laminate 50 includes the paper base layer 40, the time required for heat sealing can be prevented from becoming long. Therefore, the productivity of packaging containers can be increased while maintaining paper classification in recycling.

In addition, according to this embodiment, heat sealing can be performed at a relatively low temperature, such as 140°C. This can prevent defects such as pinholes from occurring in the seal portion formed by heat sealing. In addition, it can prevent the deposition layer 30 from peeling off from the sealant layer 20 due to damage caused by heat.

In addition, according to this embodiment, the seal strength of the seal portion formed by heat sealing the laminate 50 at a relatively low temperature such as 140°C can be increased. The seal strength of the seal portion formed at a sealing temperature of 140°C is, for example, 10N or more, may be 15N or more, may be 16N or more, or may be 18N or more. The seal strength of the seal portion formed at a sealing temperature of 140°C is, for example, 25N or less, may be 23N or less, or may be 20N or less.

This section explains how to measure the seal strength of the seal portion formed in the laminate 50.

First, as shown in FIG. 6, two laminates 50 are prepared. The inner surfaces 50x of the two laminates 50 face each other. Next, a part of the outer surface 50y of the two laminates 50 is heated at a predetermined sealing temperature while being pressurized at a predetermined sealing pressure, for example, using a heat sealer. This forms a sealed portion 55 as shown in FIG. 6. In the sealed portion 55, the inner surfaces 50x of the two laminates 50 are joined together. The pressure applied by the heat sealer to the laminates 50 is, for example, 0.1 MPa. The heat sealing time is, for example, 1 second.

Then, as shown by the dotted line in FIG. 6, the laminate 50 is cut out to prepare a test piece 70. The test piece 70 has a rectangular shape extending in a first direction D1 and a second direction D2. The second direction D2 is perpendicular to the first direction D1. FIG. 7 is a cross-sectional view of the test piece 70 in FIG. 6 cut along line A-A.

The test piece 70 includes a sealed portion 55 and a non-sealed portion 56 adjacent to the sealed portion 55 in the first direction D1. In the non-sealed portion 56, the inner surfaces 50x of the two laminates 50 are not joined together. The dimension L1 of the test piece 70 in the first direction D1 is determined so that the interval S, which will be described later, can be set to 50 mm. The dimension L2 of the test piece 70 in the second direction D2 is 15 mm. The dimension L3 of the sealed portion 55 in the first direction D1 is 5 mm or more and 20 mm or less.

Figure 8 is a diagram for explaining a method for measuring the seal strength of the seal portion 55 using a test piece 70. First, the end of the non-sealed portion 56 of one laminate 50 is held by a first gripping tool 71. The end of the non-sealed portion 56 of the other laminate 50 is held by a second gripping tool 72. Next, the gripping tools 71 and 72 are pulled in opposite directions at a speed of 300 mm/min, and the maximum value of the tensile force F1 (see Figure 9) is measured. The symbol S represents the distance between the first gripping tool 71 and the second gripping tool 72 in the direction of the tensile force F1. Figure 9 shows the change in the tensile force F1 with respect to the distance S. When the pulling starts, the distance S between the gripping tools 71 and 72 is 50 mm. When the pulling ends, the distance S between the gripping tools 71 and 72 is 90 mm. The measuring device used is a Tensilon STA-1150 manufactured by A&D Corporation.

The maximum tensile force F1 is measured for 10 test pieces 70. The average of the maximum values is calculated as the seal strength of the seal portion 55. The measurement is performed in an environment of a temperature of 25°C and a relative humidity of 50%.

(packaging container)
The packaging container of this embodiment includes the laminate 50 described above. The packaging container is, for example, a bag. The bag is also called a pouch. The shape of the bag is arbitrary. For example, various shapes such as a standing type, a side seal type, a two-sided seal type, a three-sided seal type, a four-sided seal type, an envelope seal type, a joint seal type (pillow seal type), a pleated seal type, a flat bottom seal type, a square bottom seal type, and a gusset type are adopted.

As an example of a packaging container, a pillow seal type bag will be described. In the example shown in FIG. 10, the packaging container 60 includes a front surface 61 and a back surface 62 formed by a laminate 50. Both the front surface 61 and the back surface 62 are formed by folding back a single laminate 50. Although not shown, the number of laminates 50 forming the packaging container 60 is not limited to one. The packaging container 60 may be formed by two or more laminates 50.

The packaging container 60 has a first end 63, a second end 64 that faces the first end 63 in the first direction D1, and a pair of side ends 65 that extend along the first direction D1 from the first end 63 to the second end 64. The first direction D1 may be the direction in which the laminate 50 is transported in the manufacturing process of the laminate 50 and the packaging container 60.

In the example shown in FIG. 10, the first end 63 and the second end 64 extend in a second direction D2 perpendicular to the first direction D1, so that the packaging container 60 has a rectangular outer shape. Although not shown, the first end 63 and the sixth end 14 may extend in a direction inclined with respect to the second direction D2.

The dimension M1 of the packaging container 60 in the first direction D1 is, for example, 50 mm or more, may be 70 mm or more, or may be 100 mm or more. The dimension M1 is, for example, 300 mm or less, may be 250 mm or less, or may be 200 mm or less.
The dimension M2 of the packaging container 60 in the second direction D2 is, for example, 15 mm or more, may be 20 mm or more, or may be 25 mm or more. The dimension M2 is, for example, 100 mm or less, may be 80 mm or less, or may be 60 mm or less.

As shown in FIG. 10, the packaging container 60 has a gable portion 67 that extends along the first direction D1 from the first end 63 to the second end 64 between a pair of side ends 65. The gable portion 67 may be located approximately in the center of the packaging container 60 in the second direction D2. The laminate 50 is stacked in the gable portion 67.

The packaging container 60 has a seal portion that joins the inner surfaces 50x of the laminate 50 together. The seal portion includes a first end seal portion 631 located at the first end 63, a second end seal portion 641 located at the second end 64, and a joint seal portion 671 located at the joint portion 67. The first end seal portion 631 and the second end seal portion 641 join the inner surface 50x of the laminate 50 that constitutes the front surface 61 and the inner surface 50x of the laminate 50 that constitutes the back surface 62.

The packaging container 60 has a non-sealed portion 68 located between the first end seal portion 631 and the second end seal portion 641 in the first direction D1. In the non-sealed portion 68, the inner surfaces 50x of the laminate 50 are not joined together. The non-sealed portion 68 contains the contents.

The contents may be liquid, powder or gel. The contents may be food or non-food.

According to this embodiment, heat sealing can be performed at a relatively low temperature, such as 140°C. This can prevent defects such as pinholes from occurring in the sealed portions 631, 641, and 671. This can prevent the contents from leaking from the packaging container 60. In addition, this can prevent the deposition layer 30 from peeling off from the sealant layer 20 due to damage caused by heat. This can prevent the barrier properties of the packaging container 60 from decreasing.

As shown by the dotted line in FIG. 10, a test piece 70 may be prepared by cutting out the laminate 50 constituting the packaging container 60. The test piece 70 is used to measure the seal strength of the sealed portion. The test piece 70 is cut out to include the sealed portion and the non-sealed portion 68. As shown in FIG. 10, the sealed portion of the test piece 70 may be the first end seal portion 631.

As shown in FIG. 11, the seal strength may be measured using a test piece 70 including a newly formed seal portion 69 in a packaging container 60. The seal portion 69 is formed, for example, by partially heat sealing the inner surfaces 50x of the laminate 50 at the non-sealed portion 68 after the contents are removed from the packaging container 60. This makes it possible to obtain a test piece 70 including a seal portion that has been heat sealed at any sealing temperature.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

(Example P1)
Sun Mirror CP-VR manufactured by Liko was prepared as the barrier film 10. Sun Mirror CP-VR comprises a polyolefin resin layer 21, a primer layer 22 and a vapor deposition layer 30. As shown in FIG. 4, the polyolefin resin layer 21 of Sun Mirror CP-VR comprises a first layer 21a, a second layer 21b and a third layer 21c. The first layer 21a contains polypropylene and polyethylene. The second layer 21b and the third layer 21c contain polypropylene. The vapor deposition layer 30 is an aluminum layer. In the following description, Sun Mirror CP-VR is also referred to as "barrier film A".

The DCS curve of barrier film A was measured using a thermal analyzer TA7000 series manufactured by Hitachi High-Tech Science Corporation. The DCS curve observed during the second heating is shown in Figure 12. The thickness of barrier film A was 30 μm. The weight of the sample taken from barrier film A was 4.8 mg.

Barrier film A had a main DSC peak located at 140.0°C. Barrier film A had a sub-peak DSC peak located at 128.4°C.

(Example P2)
VM-CPP2703 manufactured by Toray Film Processing Co., Ltd. was prepared as the barrier film 10. VM-CPP2703 includes a polyolefin resin layer 21 and a vapor deposition layer 30. The polyolefin resin layer 21 of VM-CPP2703 contains polypropylene. The vapor deposition layer 30 is an aluminum layer. In the following description, VM-CPP2703 is also referred to as "barrier film B."

The DCS curve of barrier film B was measured using a thermal analyzer TA7000 series manufactured by Hitachi High-Tech Science Corporation. The DCS curve observed during the second heating is shown in Figure 13. The thickness of barrier film B was 30 μm. The weight of the sample taken from barrier film B was 4.9 mg.

Barrier film B had a main DSC peak located at 147.3°C. Barrier film A had a sub-peak DSC peak located at 128.5°C.

Example 1
A laminate 50 was produced by dry laminating a substrate including a paper substrate layer 40 and a barrier film A via an adhesive layer 45. As the paper substrate layer 40, unbleached kraft paper Tokai Kraft C manufactured by Tokushu Tokai Paper Co., Ltd. was used. The basis weight of the paper substrate layer 40 was 50 g/ ^m2 . The thickness of the barrier film A was 30 μm. As the adhesive constituting the adhesive layer 45, PASLIM manufactured by DIC was used. PASLIM comprises a composition containing polyester polyol and an isocyanate compound. Specifically, PASLIM contains a base material VM001 and a curing agent VM080CP manufactured by DIC. The coating amount of the adhesive was 3 g/ ^m2 . In the following description, Tokai Kraft C is also referred to as kraft paper A, and PASLIM is also referred to as adhesive A. The weight ratio of the paper substrate layer 40 in the laminate 50 was 63%.

The layer structure of the laminate 50 of Example 1 is expressed as follows.
Kraft paper A/Adhesive A/VM-AL/Primer/Polyolefin A
The leftmost layer is a layer that forms an outer surface 50y of the laminate 50. The rightmost layer is a layer that forms an inner surface 50x of the laminate 50.
“VM-AL” means a vapor-deposited aluminum layer. “Polyolefin A” means the polyolefin resin layer 21 of the barrier film A.

Example 2
A laminate 50 was produced by dry laminating a substrate including a paper substrate layer 40 and a barrier film A via an adhesive layer 45. As the paper substrate layer 40, Taio Atlas, an unbleached kraft paper manufactured by Daio Paper Corporation, was used. The basis weight of the paper substrate layer 40 was 50 g/ ^m2 . The thickness of the barrier film A was 40 μm. As the adhesive constituting the adhesive layer 45, PASLIM manufactured by DIC was used. The application amount of the adhesive was 3 g/ ^m2 . In the following description, Taio Atlas is also referred to as kraft paper B. The weight ratio of the paper substrate layer 40 in the laminate 50 was 56%.

The layer structure of the laminate 50 of Example 2 is expressed as follows.
Kraft paper B/adhesive A/VM-AL/primer/polyolefin A

Example 3
A laminate 50 was produced by dry laminating a substrate including a paper substrate layer 40 and a barrier film A via an adhesive layer 45. As the paper substrate layer 40, unbleached kraft paper Tokai Kraft C manufactured by Tokushu Tokai Paper Co., Ltd. was used. The basis weight of the paper substrate layer 40 was 50 g/ ^m2 . The thickness of the barrier film A was 30 μm. As the adhesive constituting the adhesive layer 45, an adhesive containing a base agent RU3900 and a hardener H789 manufactured by Rock Paint was used. In the following description, the adhesive containing RU3900 and H789 is also referred to as adhesive B. The coating amount of the adhesive was 3 g/ ^m2 . The weight ratio of the paper substrate layer 40 in the laminate 50 was 63%.

The layer structure of the laminate 50 of Example 3 is expressed as follows.
Kraft paper A/adhesive B/VM-AL/primer/polyolefin A

(Comparative Example 1)
A laminate 50 was produced in the same manner as in Example 1, except that the barrier film B was used as the barrier film 10. The thickness of the barrier film B was 30 μm.

The layer structure of the laminate 50 of Comparative Example 1 is expressed as follows.
Kraft paper A/adhesive A/VM-AL/polyolefin B
“Polyolefin B” means the polyolefin resin layer 21 of the barrier film B.

(Comparative Example 2)
A laminate 50 was produced in the same manner as in Example 2, except that the barrier film B was used as the barrier film 10. The thickness of the barrier film B was 40 μm.

The layer structure of the laminate 50 of Comparative Example 2 is expressed as follows.
Kraft paper B/adhesive A/VM-AL/polyolefin B

(Comparative Example 3)
A laminate 50 was produced in the same manner as in Example 3, except that the barrier film B was used as the barrier film 10. The thickness of the barrier film B was 30 μm.

The layer structure of the laminate 50 of Comparative Example 3 is expressed as follows.
Kraft paper A/adhesive B/VM-AL/polyolefin B

[Measurement of seal strength]
The laminates 50 of Examples 1 to 3 and Comparative Examples 1 to 3 were heated at a predetermined sealing temperature while being pressurized at a predetermined sealing pressure to produce the test pieces 70 shown in Figs. 6 and 7. The pressure applied to the laminates 50 by the heat sealer was 0.1 MPa. The heat sealing time was 1 second. The sealing temperatures were 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 150°C, or 160°C. The dimension L1 of the test piece 70 in the first direction D1 was 50 mm. The dimension L2 of the test piece 70 in the second direction D2 was 15 mm. The dimension L3 of the seal portion 55 in the first direction D1 was 10 mm.

The seal strength of the seal portion 55 of the test piece 70 created at each sealing temperature was measured using a Tensilon STA-1150 manufactured by A&D Corporation. The environment during measurement was a temperature of 25°C and a relative humidity of 50%. The measurement results are shown in Figures 14 and 15.

When the sealing temperature was 130° C., the sealing strength of Examples 1 to 3 was 7N or more, while the sealing strength of Comparative Examples 1 to 3 was less than 1N.
When the sealing temperature was 135° C., the sealing strengths of Examples 1 to 3 were 16 N or more, while the sealing strengths of Comparative Examples 1 to 3 were less than 1 N.
When the sealing temperature was 140° C., the sealing strength of Examples 1 to 3 was 15 N or more, while the sealing strength of Comparative Examples 1 to 3 was less than 10 N.

[Leak evaluation]
The laminates 50 of Examples 1 to 3 and Comparative Examples 1 to 3 were heat-sealed to produce a packaging container 60 as shown in Fig. 10. The packaging container 60 was filled with 3 g of sugar. The sealing temperature was 140°C. A KOMACK stick packaging machine SS-500.4 was used as the heat-sealing device. The dimension M1 of the packaging container 60 in the first direction D1 was 120 mm. The dimension M2 of the packaging container 60 in the second direction D2 was 35 mm.

The packaging container 60 was placed in a pressurized chamber, and the pressure in the pressure chamber was maintained at 1.2 MPa for 10 minutes. During this time, it was confirmed whether the packaging container 60 was dented. If there is a leak in the packaging container 60, the pressure in the packaging container 60 is almost the same as in the pressurized chamber, so the packaging container 60 is not dented. If there is no leak in the packaging container 60, the air pressure inside the packaging container 60 is lower than the pressure in the pressurized chamber, so the packaging container 60 is dented. The results of this test are shown in the "Pressurized Leak" column in Figure 14. "◯" means that a dent occurred in the packaging container 60. "△" means that no dent occurred in the packaging container 60.

A submerged leak test was conducted using a Komak Creek Tester LT25-A manufactured by Komak Co., Ltd. The packaging container 60 was submerged in water for 5 minutes at a pressure of 0.02 MPa. During this process, it was confirmed whether air bubbles were generated from the packaging container 60. If there is a leak in the packaging container 60, air bubbles will be generated. If there is no leak in the packaging container 60, no air bubbles will be generated. The results of the submerged leak test are shown in the "Submerged Leak" column in Figure 14. "◯" means that no air bubbles were generated from the packaging container 60. "△" means that air bubbles were generated from the packaging container 60.

10 Barrier film 20 Sealant layer 20x First surface 20y Second surface 21 Polyolefin resin layer 21a First layer 21b Second layer 21c Third layer 22 Primer layer 30 Vapor deposition layer 40 Paper base layer 41 Printed layer 45 Adhesive layer 50 Laminate 50x Inner surface 50y Outer surface 55 Sealed portion 56 Non-sealed portion 60 Packaging container 61 Surface 62 Back surface 63 First end 631 First end sealed portion 64 Second end 641 Second end sealed portion 65 Side end 67 Joint portion 671 Joint sealed portion 68 Non-sealed portion 70 Test piece

Claims (9)

A laminate comprising, in order from the outside to the inside, at least a paper base layer, an adhesive layer, a deposition layer, and a sealant layer,
The weight ratio of the paper base layer in the laminate is greater than 50%,
the sealant layer includes a first surface located on an inner side and a second surface located opposite the first surface;
The sealant layer comprises a polyolefin resin layer constituting the first surface and a primer layer constituting the second surface ,
the primer layer is in contact with the deposition layer,
the adhesive layer is in contact with the deposition layer;
The polyolefin resin layer contains polypropylene, which is an ethylene-propylene random copolymer, as a main component and also contains polyethylene,
The polyolefin resin layer has a DSC main peak located at 145° C. or lower. The laminate according to claim 1, wherein the adhesive layer is an adhesive layer. The laminate according to claim 2, wherein the adhesive layer comprises a cured product of a composition containing a polyester polyol and an isocyanate compound. The polyolefin resin layer has a DSC sub-peak located at a lower temperature side than the DSC main peak,
The laminate according to claim 1 , wherein the difference between the temperature of the DSC main peak and the temperature of the DSC sub-peak is 15° C. or less. The laminate according to claim 1 , wherein the primer layer comprises a urethane-based resin or a cellulose-based resin. The laminate according to claim 5 , wherein the primer layer comprises a cellulose-based resin. The laminate according to any one of claims 1 to 6, wherein the vapor deposition layer includes an aluminum vapor deposition layer. The laminate according to claim 1 , wherein the paper base layer has a basis weight of 20 g/m ² or more and 120 g/m ² or less. A packaging container comprising the laminate according to any one of claims 1 to 8 .