JP2024134140A - Packaging materials - Google Patents

Abstract

To provide a packaging material with reduced paper base material tear and high adhesive strength even without a resin layer for adhesion made of polyethylene resin between the paper base material and the sealant layer.SOLUTION: The packaging material includes: a laminate including a paper base material 11 and a sealant layer 12, characterized in that: (1) paper has a loading capacity of 40 to 120 g/m2; (2) the sealant layer 12 contains a resin component having sealant properties and a softening point of 69 to 75°C; and (3) no polyethylene resin-contained layer is interposed between the paper base material 11 and the sealant layer 12.SELECTED DRAWING: Figure 2

Description

The present invention relates to a novel packaging material. More specifically, the present invention relates to a packaging material that has sealability.

Traditionally, packaging materials used for food, medicines, etc. have been required to be environmentally friendly, and efforts have been made to reduce the amount of resin and use paper instead. However, when forming a three-dimensional package (packaging bag, container, etc.) from the packaging material by heat sealing, reducing the amount of resin makes it more likely for pinholes to occur, resulting in a problem of reduced performance, such as sealing ability, required of the packaging material.

Therefore, studies have been conducted to reduce the amount of resin while also reducing pinholes, thereby attempting to reduce the environmental impact of packaging materials. For example, a paper laminated sheet has been proposed that includes, in order, a paper base layer, an anchor coat layer, an adhesive resin layer made of a polyolefin resin, and a sealant layer made of a polyolefin resin, and is characterized in that, when the weight of the paper base layer is Xg/ ^m2 and the weight of the entire paper laminated sheet is Yg/ ^m2 , Y/2<X<120 (Patent Document 1).

In conventional packaging materials, an adhesive resin layer is formed between the paper base material and the sealant layer, and polyethylene-based resins and the like are generally used as the adhesive resin layer. Without such an adhesive resin layer, the paper base material cannot be given strength, resulting in problems such as the paper base material tearing unintentionally and exposing the contents, or the paper base material tearing irregularly when opening, making it difficult to open properly.

JP 2022-069297 A

However, as in Patent Document 1, in a layer structure in which a sealant layer is formed on an adhesive resin layer of a polyethylene resin, the packaging material is designed to be opened by the cohesive peeling of the sealant layer when it is opened, but if the polyethylene resin adhesive layer reaches the container side during heat sealing, the polyethylene and the container will fuse together, making it difficult to open the packaging material with your fingers.

On the other hand, it is also possible to eliminate the adhesive resin layer of polyethylene resin, but simply eliminating the adhesive resin layer of polyethylene resin reduces the strength of the entire packaging material, and there is a risk that the paper base material will tear when opening, and that the package will open in an unintended way. Another method is to provide a peeling layer or the like to make it easier to peel the paper base material and the sealant layer in order to prevent the paper base material from tearing, but in that case, the adhesive strength between the paper base material and the sealant layer will be reduced, and there is a risk that the package will be opened unintentionally.

Therefore, the main objective of the present invention is to provide a packaging material that reduces tearing of the paper base material and has high adhesive strength, even without an adhesive resin layer made of a polyethylene resin between the paper base material and the sealant layer.

As a result of extensive research into the problems of the prior art, the inventors discovered that a laminate having a specific composition and structure can achieve the above-mentioned objectives, and thus completed the present invention.

That is, the present invention relates to the following packaging material.
1. A laminate comprising a paper substrate and a sealant layer,
(1) The paper has a basis weight of 40 to 120 g/ ^m2 ,
(2) The sealant layer contains a resin component having a sealant property and has a softening point of 69 to 75° C.,
(3) No polyethylene resin-containing layer is interposed between the paper base material and the sealant layer.
A packaging material characterized by:
2. The packaging material according to item 1, further comprising a primer layer between the paper substrate and the sealant layer, the primer layer containing at least one of an acrylic resin, a vinyl chloride-vinyl acetate copolymer resin, and a polyester resin.
3. The packaging material according to claim 1, wherein the paper is a high-density paper having a density of 0.8 to 1.0 g/ ^cm3 .
4. A package or container comprising the packaging material according to any one of items 1 to 3.

According to the present invention, it is possible to provide a packaging material that reduces tearing of the paper base material and has high adhesive strength, even without an adhesive resin layer made of a polyethylene resin between the paper base material and the sealant layer.

For this reason, in a package or container using the packaging material of the present invention, the paper base material is not easily torn before opening, and high adhesive strength can be maintained, reducing the phenomenon of the package or container tearing unintentionally. Furthermore, when opening, the paper base material itself is not easily torn, so it is possible to avoid unintentional opening or irregular opening.

In particular, in the present invention, when a specific primer layer is formed between the paper substrate and the sealant layer, the peeling interface can be between the primer layer and the sealant layer when the paper is opened. This makes it difficult for the paper to tear when the paper is opened (when the packaging material is peeled off), and as a result of being able to prevent unexpected tearing, the packaging material can be opened or peeled off with fingers as designed. In addition, even if the paper substrate is a paper substrate other than a paper substrate containing metal foil (e.g., paper/PET film, etc.), it is possible to obtain the same excellent adhesion, peelability, etc. by selecting the type of primer.

Furthermore, in the packaging material of the present invention, it is not necessary to form an adhesive resin layer of polyethylene resin between the base layer and the sealant layer, so the amount of polyethylene resin used can be reduced, making it possible to provide a high-quality environmentally friendly product. In addition, the extrusion process of polyethylene resin, which was previously required, can be omitted, which is advantageous in terms of productivity and economy.

1 is a diagram showing an example of a layer structure of a packaging material of the present invention. FIG. 2 is a diagram showing another example of the layer structure of the packaging material of the present invention.

1. Packaging Material The packaging material of the present invention is a laminate including a paper base material including paper and a sealant layer,
(1) The paper has a basis weight of 40 to 120 g/ ^m2 ,
(2) The sealant layer contains a resin component having a sealant property and has a softening point of 69 to 75° C.,
(3) No polyethylene resin-containing layer is interposed between the paper base material and the sealant layer.
It is characterized by:

An example of the basic layer structure of the packaging material of the present invention is shown in Figure 1. The packaging material 10 of the present invention has a structure in which a sealant layer 12 is laminated to a paper base material 11 containing paper. Usually, the sealant layer 12 is a layer that is joined by heat sealing (HS) or the like while in contact with the container 20, as shown in Figure 1, for example. Therefore, in the present invention, it is preferable that the sealant layer is usually disposed as the outermost layer of the packaging material of the present invention. The sealant layer may be formed over the entire surface of the paper base material, or may be formed on only a part of it.

As shown in Figure 1, the packaging material of the present invention does not have a polyethylene resin-containing layer between the paper substrate 11 and the sealant layer 12, as is the case with conventional packaging materials. This effectively avoids the peeling problems that are a problem with conventional packaging materials.

In FIG. 1, the paper base material 11 and the sealant layer 12 are laminated so as to be in direct contact with each other, but they may be laminated with other layers interposed therebetween. However, no polyethylene resin-containing layer is included between the paper base material and the sealant layer. For example, in the packaging material 10' shown in FIG. 2A, a primer layer PR is formed between the paper base material 11 and the sealant layer 12. In this case, the sealant layer 12 may be formed on the entire surface of the primer layer PR material, or may be formed on a part of it. Furthermore, as in the packaging material 10" shown in FIG. 2B, other layers (e.g., a printing layer, an overcoat layer, a surface protection layer, etc.) may be laminated on the surface opposite to the side where the paper base material 11 contacts the primer layer PR. In particular, in the present invention, as shown in the packaging material 10' or packaging material 10", it is preferable that the laminate includes at least a paper base material/primer layer/sealant layer configuration. It is preferable that these layers are laminated in a state of direct contact with each other. This makes it possible to obtain high adhesive strength as well as good peelability. Therefore, for example, as shown in FIG. 1, after the packaging material is bonded to the container, the desired sealing property is maintained, and the packaging material can be peeled off cleanly from the container without any trouble such as the packaging material being torn during peeling. The following describes each layer that can constitute the packaging material of the present invention.

a) Paper substrate The paper substrate functions as a support layer of the packaging material of the present invention and plays a role in imparting rigidity, etc. to the laminate. The paper substrate may be a single layer or multiple layers as long as at least one layer contains paper.

When the paper base material is multi-layered, the materials other than paper are not particularly limited, and may be, for example, one or more layers composed of at least one of metal foil, metal vapor deposition film (resin film vapor-deposited with metal components), resin film, etc. Examples of the metal components of metal foil or metal vapor deposition film include aluminum, iron, copper, etc., and alloys containing these. Examples of resin components of resin films include polyester resin films such as polyethylene terephthalate (PET), olefin resin films such as polypropylene and polyethylene, etc.

In particular, in the present invention, it is preferable to use a paper base material in which one or more layers of aluminum foil or aluminum vapor deposition film are laminated to paper. This makes it possible to obtain a higher barrier property against, for example, light, oxygen, moisture, etc. Furthermore, when the paper base material is a laminate of multiple materials, an adhesive layer may be provided between the materials. Therefore, for example, "paper/adhesive layer/aluminum foil", "paper/adhesive layer/metal vapor deposition film", "aluminum foil/adhesive layer/paper/adhesive layer/aluminum foil", "metal vapor deposition film/adhesive layer/paper/adhesive layer/metal vapor deposition film" and the like can be suitably adopted as a multi-layer paper base material.

It is also possible to use a paper substrate having any layer, such as an OP layer (overprint layer, print protection layer, surface protection layer) or a print layer, laminated on the side opposite the sealant layer.

The paper substrate may be subjected to a surface treatment such as plasma treatment at least on the surface on the sealant layer side. This can further increase the adhesion (bonding) between the substrate and the sealant layer. In addition, the paper substrate or the sealant layer surface may be subjected to a treatment such as unevenness treatment using an additive (preferably filler particles) or unevenness treatment by embossing. The height of such unevenness is not limited, but is preferably around 5 to 60 μm, and more preferably 20 to 50 μm. This can suppress adhesion to the contents when used as a packaging material.

The basis weight of the paper contained in the paper base material is usually about 40 to 120 g/m ² , particularly preferably 45 to 90 g/m ² , and even more preferably 50 to 70 g/m ^2. By setting the basis weight at such a level, it is possible to obtain the necessary adhesive strength when the sealant layers are bonded to each other, to the paper base material, or to other packaging materials via the sealant layer, while still having the strength required for a packaging body.

The density of the paper is not particularly limited, but is usually preferably about 0.6 to 1.0 g/ ^cm3 , and more preferably 0.8 to 1.0 g/ ^cm3 . Such so-called high density paper is particularly preferred from the viewpoint of preventing the paper from tearing.

When the paper base material contains aluminum foil, the thickness of the aluminum foil is preferably in the range of 6 to 20 μm. There are also no particular limitations on the composition of the aluminum foil, and any aluminum foil used as a packaging material can be suitably used. There are also no particular limitations on the condition of the aluminum foil, but it is preferable for it to be a soft foil.

When the paper substrate contains an aluminum vapor deposition film, the thickness of the aluminum vapor deposition film is usually preferably in the range of 10 nm or more and 1 μm or less.

The thickness (total thickness) of the paper base material is not limited, but can be set appropriately depending on the materials of the layers constituting the paper base material, the application of the laminate of the present invention, etc. Generally, it can be set appropriately within the range of about 9 to 80 μm, but is not limited to this.

b) Primer layer In the laminate of the present invention, the primer layer is not essential, but it is preferable to provide a primer layer between the paper substrate and the sealant layer. In the present invention, the primer layer mainly serves to make the sealant layer more easily adhered to the paper substrate. It can also contribute to better peelability.

The type of primer layer is not particularly limited, and known or commercially available primer components can be used. For example, a primer containing at least one resin component selected from acrylic resin, vinyl chloride-vinyl acetate copolymer resin, and polyester resin can be suitably used. These can be selected appropriately depending on the material of the substrate. For example, when the paper substrate is paper alone, it is preferable to use an acrylic resin as the primer. Also, for example, when the paper substrate is provided with a metal foil such as aluminum foil, it is preferable to use a vinyl chloride-vinyl acetate copolymer resin as the primer. By selecting such resin components, it is possible to reduce tearing of the paper substrate and obtain high adhesive strength.

The amount of the primer layer is not particularly limited, but is preferably about 0.1 to 3.0 g/ ^m2 in terms of dry weight from the viewpoint of adhesive strength. Therefore, it may be ^about 0.3 to 0.8 g/m2, for example.

The method for forming the primer layer is not limited as long as it can form a layer having the above-mentioned structure, but typically a method including a step of applying a primer layer-forming coating liquid to the substrate surface can be preferably used.

The coating liquid for forming the primer layer can be, for example, a solution in which the above-mentioned resin component (adhesive resin) is dissolved in a solvent or a dispersion in which the resin component is dispersed in a solvent.

The solvent is not limited and can be appropriately selected depending on the type of resin component. For example, in addition to water, ethanol, methanol, cyclohexane, toluene, acetone, isopropyl alcohol (IPA), propylene glycol, hexylene glycol, butyl diglycol, pentamethylene glycol, normal pentane, normal hexane, hexyl alcohol, methyl ethyl ketone, methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isopropyl acetate, isopentyl acetate, normal butyl acetate, normal propyl acetate, normal pentyl acetate (also known as normal amyl acetate), cyclohexane, isobutyl alcohol, isopropyl alcohol, isopentyl alcohol, ethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-butyl ether, ethylene glycol monomethyl ether, ortho-dichlorobenzene, xylene, cresol, chlorobenzene, cyclohexanol, cyclohexanone, N,N-dimethylformamide, tetrahydrofuran, 1,1,1-trichloroethane, toluene, etc. can be mentioned. These can be used alone or in combination of two or more.

The solids concentration of the coating liquid for forming the primer layer can be set appropriately in consideration of, for example, coatability, and can be in the range of, for example, about 5 to 60% by mass, but is not limited to this.

The method for preparing the coating liquid for forming the primer layer is not particularly limited, and it can be obtained by adding the resin components and the like to a solvent and mixing them. In addition, the order in which each component is added is also not particularly limited.

The method of applying the primer layer-forming coating liquid is not particularly limited, and the primer layer can be applied to the substrate layer by known methods such as roll coating, various gravure coatings, bar coater, doctor blade coating, comma coater, spray coating, and brush coating.

Then, the formed coating film can be dried as necessary. By drying, the solvent can be evaporated and a primer layer can be formed on the substrate layer. Drying conditions can be set appropriately depending on, for example, the type of solvent and the amount of coating. The temperature can be set in the range of, for example, 50 to 250°C, but is not limited to this. The drying time can be set in the range of, for example, 5 seconds to 60 minutes, but is not limited to this.

c) Sealant layer In the present invention, the sealant layer is a layer that is mainly provided with heat sealability. When forming into a packaging material, the sealant layer is melted by heating and adhered to each other or to a paper substrate or other packaging material (container), so that it can be formed into a desired shape.

The sealant layer is composed of a composition (sealant component) containing a resin component with sealant properties. In the present invention, the softening point of the sealant layer (sealant component) is set to a range of 69 to 75°C. By setting it in this range, when actually used as a packaging material, it has high adhesive strength sealing properties while also having a certain degree of flexibility at room temperature, and paper tearing of the paper base material can be reduced. When a resin component with a softening point of less than 69°C is used, heat sealing is difficult, making it difficult to use it as a packaging material in the first place. In addition, when the softening point exceeds 75°C, there is a problem that layers other than the sealant layer are easily damaged by the high temperature during heat sealing.

The softening point can be designed not only by the main component of the resin component, but also by additives. Specifically, the main component of the resin constituting the sealant component is not limited, and examples include at least one of ethylene-vinyl acetate copolymer, polyolefin, synthetic rubber, polyurethane, polyamide, etc. Therefore, for example, an ethylene-vinyl acetate copolymer-based hot melt agent can be preferably used. Also, for example, a sealant component containing a polyolefin resin (polyethylene, etc.) and wax, a tackifier, an ethylene-vinyl acetate copolymer, etc. as additives can be used. In this case, it can be preferably adjusted by the composition and/or the amount of tackifier (terpene resin). These can also be used as commercially available products.

The viscosity of the sealant components is not particularly limited, but a melt viscosity of about 3 to 6 Pa·s at 160°C (particularly 3.5 to 5.5 Pa·s) is preferred from the viewpoint of obtaining adequate adhesion to the paper substrate.

The amount of the sealant layer formed is not particularly limited, but from the viewpoint of adhesive strength, it is preferable to set the dry weight at ^about 5 to 25 g/m2. Therefore, it can be set at, for example, ^about 15 to 20 g/m2.

The method for forming the sealant layer is not limited as long as it can form a layer having the above-mentioned structure, but typically a method including a step of applying a sealant liquid to the surface of the paper substrate or the sealant layer can be preferably used.

As the sealant liquid, for example, a solution in which a resin component having sealant properties is dissolved in a solvent or a dispersion in which a resin component having sealant properties is dispersed in a solvent can be suitably used. In addition, a commercially available sealant agent (such as a hot melt agent) can also be used.

When a solvent is used, the type is not limited and can be selected appropriately depending on the type of resin component having sealant properties. Examples of the solvent include water, ethanol, methanol, cyclohexane, toluene, acetone, isopropyl alcohol (IPA), propylene glycol, hexylene glycol, butyl diglycol, pentamethylene glycol, normal pentane, normal hexane, hexyl alcohol, methyl ethyl ketone, methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isopropyl acetate, isopentyl acetate, normal butyl acetate, normal propyl acetate, normal pentyl acetate (also known as normal amyl acetate), cyclohexane, isobutyl alcohol, isopropyl alcohol, isopentyl alcohol, ethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-butyl ether, ethylene glycol monomethyl ether, ortho-dichlorobenzene, xylene, cresol, chlorobenzene, cyclohexanol, cyclohexanone, N,N-dimethylformamide, tetrahydrofuran, 1,1,1-trichloroethane, toluene, and the like. These can be used alone or in combination of two or more.

The solids concentration of the sealant liquid can be set appropriately, taking into consideration, for example, coatability, and can be in the range of, for example, 5 to 60% by mass, but is not limited to this.

The method for preparing the sealant liquid is not particularly limited, and it can be obtained by adding the resin components to a solvent and mixing. In addition, the order in which each component is added is also not particularly limited.

The method for applying the sealant liquid is not particularly limited, and it can be applied to the paper base layer by known methods such as roll coating, various gravure coatings, bar coater, doctor blade coating, comma coater, spray coating, brush coating, etc.

The coating film formed can then be dried as necessary. The solvent is evaporated by drying, and a sealant layer can be formed on the surface of the paper substrate layer or primer layer. Drying conditions can be set appropriately depending on, for example, the type of solvent and the amount of coating. The temperature can be set in the range of, for example, 50 to 250°C, but is not limited to this. The drying time can be set in the range of, for example, 5 seconds to 60 minutes, but is not limited to this.

d) Polyethylene resin-containing layer One of the features of the packaging material of the present invention is that it does not include a polyethylene resin-containing layer formed between the base layer and the sealant layer (heat seal layer) in conventional packaging materials. This makes it possible to reduce the amount of polyethylene resin used, while the disadvantages of this reduction (problems with peelability, adhesion, etc.) can be solved by the configuration of the laminate of the present invention.

3. Use of the packaging material of the present invention The packaging material of the present invention can be suitably used as a material for forming a package for packaging or containing various products. The packaging material of the present invention can also be suitably used as a material for forming a molded body such as a container as a package. That is, the present invention includes a package or container containing the packaging material of the present invention. More specifically, the package or container can include a package or container in which at least a part or all of the sealant layer in the packaging material is heat sealed, and the packaging material is opened at the heat-sealed portion when the packaged item is removed.

As an embodiment of the packaging material of the present invention, it is preferable to have a layer structure including at least three layers: a paper base material, a primer layer, and a sealant layer. Examples of embodiments including these three layers include "OP layer (overprint layer)/printing layer/primer layer/paper base material/aluminum foil/primer layer/sealant layer" and "OP layer/printing layer/primer layer/paper base material/primer layer/sealant layer". In this way, by adopting a packaging material including the above three layers and arranged so that the sealant layer is the outermost layer, it is possible to obtain higher adhesion between sealant layers, between the sealant layer and other packaging materials, between the sealant layer and other containers, etc. (particularly heat sealing), and it is possible to obtain good peelability without the paper base material breaking during peeling (opening) the packaging material.

In this way, the packaging material of the present invention has an exposed sealant layer as the outermost layer, so that the desired package can be formed by heat sealing the sealant layers together or with the sealant layer of another packaging material. Furthermore, the packaging material of the present invention can be suitably used as a lid material that is a component of a package, so that the contents can be sealed by heat sealing the sealant layer to the container (opening).

The shape of the packaging body is not particularly limited, and it can be suitably applied to, for example, molded packaging bodies, strip-shaped side covers, wrapping paper, trays, tubes, and various types of bags. There is also no particular limit to the shape of the bag body, and it can be suitably used for any type, such as bottom-sealed bags, side-sealed bags, pillow bags, gusseted bags, and pouches (standing pouches). In addition, as the above-mentioned container, any shape, such as a bottle shape or a cup shape, can be applied.

The following examples and comparative examples are presented to more specifically explain the features of the present invention. However, the scope of the present invention is not limited to the examples.

[Example 1]
A paper substrate was prepared by laminating a 7 μm thick aluminum foil (1N30, manufactured by Toyo Aluminum Co., Ltd.) of the same size to a commercially available Ryuo coated paper (basis weight 80 g/m ² , A4 size) using a commercially available ester-based adhesive and drying the resulting paper. A primer layer was then formed by applying a commercially available vinyl chloride-vinyl acetate copolymer resin (water-based) to the aluminum foil side of the paper substrate in a dry weight of 0.5 g/m ² and drying the resulting paper. A commercially available ethylene-vinyl acetate copolymer hot melt agent (softening point 72°C, melt viscosity 4.5 Pa·s at 160°C) was then applied to the primer layer at 20 g/m ² as a sealant layer to obtain a packaging material.

[Example 2]
A packaging material was obtained in the same manner as in Example 1, except that the paper used was a commercially available high-quality paper (basis weight: 40 g/m ² ).

[Example 3]
A packaging material was obtained in the same manner as in Example 1, except that the paper used was commercially available Ryuo coated paper (basis weight 120 g/m ² ).

[Example 4]
A packaging material was obtained in the same manner as in Example 1, except that the paper used was a commercially available high-density paper (basis weight 60 g/m ² , density 0.80 g/cm ³ ).

[Example 5]
A packaging material was obtained in the same manner as in Example 1, except that the hot melt agent had a softening point of 69° C. and a melt viscosity of 4.0 at 160° C.

[Example 6]
A packaging material was obtained in the same manner as in Example 1, except that the hot melt agent had a softening point of 75° C. and a melt viscosity of 5.0 at 160° C.

[Example 7]
A packaging material was obtained in the same manner as in Example 1, except that a commercially available acrylic resin (containing acetone as a solvent) was applied as a primer so as to have a dry weight of 0.5 g/ ^m2 and then dried to form a primer layer.

[Example 8]
A commercially available Ryuo coated paper (basis weight 80 g/m ² , A4 size) was prepared as the paper substrate. One side of the paper was coated with a commercially available vinyl chloride-vinyl acetate copolymer resin (water-based) as a primer at a dry weight of 0.5 g/m ² and dried, and then a commercially available ethylene-vinyl acetate copolymer hot melt agent (softening point 72°C, melt viscosity 4.5 at 160°C) was coated on the formed primer ^layer to form a sealant layer, thereby obtaining a packaging material.

[Example 9]
A commercially available Ryuo coated paper (basis weight 80 g/ ^m2 , A4 size) was prepared as the paper substrate. A commercially available acrylic resin was applied as a primer to one side of the paper in a dry weight of 0.5 g/ ^m2 and dried. A commercially available ethylene-vinyl acetate copolymer hot melt agent (softening point 72°C, melt viscosity 4.5 at 160°C) was applied to the formed primer layer in an amount of 20 g/ ^m2 to form a sealant layer, thereby obtaining a packaging material.

[Comparative Example 1]
A packaging material was obtained in the same manner as in Example 1, except that the hot melt agent had a softening point of 76° C. and a melt viscosity of 7.0 at 160° C.

[Comparative Example 2]
A packaging material was obtained in the same manner as in Example 1, except that the paper used was commercially available Japanese paper (weight per unit area: 37 g/m ² ).

[Comparative Example 3]
A packaging material was obtained in the same manner as in Example 1, except that the paper was a commercially available OS coated paper (basis weight: 127 g/m ² ).

[Reference Example 1]
A packaging material was obtained in the same manner as in Example 1, except that a polyethylene-based resin layer having a thickness of 20 μm was formed between the paper substrate and the sealant layer.

[Test Example 1]
The packaging materials (lid materials) obtained in the above respective Examples and Comparative Examples were heat-sealed to 71-caliber paper/PE containers under conditions of 150° C., 1 kg/cm ² ×1 second to prepare sealed samples.
The packaging was then opened by hand by pinching the edge of the packaging material, and the paper substrate was rated as "x" if it was torn and severely torn, rated as "△" if the paper substrate was not torn but part of the paper peeled off, and rated as "◯" if the paper substrate was not torn at all and no paper peeling off was performed. The results are shown in Table 1.

[Test Example 2]
The adhesive strength between the paper substrate and the sealant layer was measured. Specifically, each packaging material was cut to a width of 15 mm, and heat-sealed to a commercially available 20 μm thick polyethylene sheet that resembled a PE container at 150°C and 1 kg/ ^cm2 x 1 second to prepare a sealed sample, and a tensile tester (Shimadzu Corporation EZ-LX 100N) was used at room temperature (20°C) to peel off a small amount of the paper substrate from the edge of the sheet sample, bend the paper substrate 180°, and not bend the polyethylene sheet, at a peel speed of 200 mm/min, sample width 7 mm, and chuck distance 100 mm in a state where the interface between the paper substrate and the polyethylene sheet peeled off at 180°.
The peel strength (N/15mm) referred to in this specification is obtained by measuring the peel strength of the above-mentioned strip-shaped sample with a sample width of 7 mm, and converting the value into the peel strength when the sample width is 15 mm (15/7 times). As a guideline for a sample having a necessary and sufficient adhesive strength and also capable of being peeled off, a peel strength of 0.5 N/15 mm or more and less than 2.5 N/15 mm was evaluated as "○", and a peel strength of less than 0.5 N/15 mm and more than 2.5 N/15 mm was evaluated as "×". The results are shown in Table 1.

As is clear from the above results, the packaging material of the present invention, even without an adhesive resin layer made of a polyethylene resin between the paper base material and the sealant layer, has high adhesive strength similar to Reference Example 1, which contains a polyethylene resin layer, and when opened or peeled off, the paper base material is less likely to break, and can be easily peeled off with fingers as designed. At the same time, since there is no adhesive resin layer made of a polyethylene resin, the problem of fusion between the adhesive resin layer and a container, etc., during heat sealing can be avoided in advance.

Claims (4)

A laminate comprising a paper substrate and a sealant layer,
(1) The paper has a basis weight of 40 to 120 g/ ^m2 ,
(2) The sealant layer contains a resin component having a sealant property and has a softening point of 69 to 75° C.,
(3) No polyethylene resin-containing layer is interposed between the paper base material and the sealant layer.
A packaging material characterized by: The packaging material according to claim 1, further comprising a primer layer between the paper substrate and the sealant layer, the primer layer containing at least one of an acrylic resin, a vinyl chloride-vinyl acetate copolymer resin, and a polyester resin. The packaging material according to claim 1, wherein the paper is a high-density paper having a density of 0.8 to 1.0 g/ ^cm3 . A package or container comprising the packaging material according to any one of claims 1 to 3.