JP7106830B2 - packaging material - Google Patents

Description

The present invention relates to packaging materials. More particularly, the present invention relates to a packaging material that allows easy opening of packages containing foods, medicines, and the like.

Plastic film packaging materials are used to fill and package foods such as cheese, ham, sausage, kamaboko, sweet bean jelly, and jelly, and to package pharmaceuticals such as powders. For example, sliced cheese, which is formed into a sheet of processed cheese with a thickness of about several mm and a size of about 10 cm square, is directly and individually wrapped in a plastic film. They are sold in a form in which they are stacked and housed in a packaging bag such as a pillow-shaped bag.

An example of a sliced cheese packaging material will be used to explain such an individual package for food. An example of a conventional sliced cheese packaging is a laminated plastic film with a sealing layer on one side of the substrate.

An example of a process of continuously packaging sliced cheese with a filling machine using a sliced cheese packaging material will be described. A long sliced cheese packaging material is set in the supply part of the filling machine, pulled out in the longitudinal direction, and while being continuously moved at a predetermined line speed, both ends of the sliced cheese packaging material in the short direction are drawn and overlapped. Align and center-seal the overlapped portion to form a cylinder. Molten processed cheese is injected into this cylindrical inner space and then pressed with a roll so as to have a predetermined cheese thickness to form a flat shape. The processed cheese is sealed in the package by pinching the openings at both ends in the longitudinal direction of the film, and heat-sealing the seal layers located on the inner surfaces of the films in close contact with each other (side seal). After sealing, the contents of the processed cheese are cooled and solidified by passing through water. After cooling and solidifying, air and brushes are used to remove moisture from the package surface. After that, it is cut into a predetermined size to form an individual package, and a plurality of individual packages are stacked and packed in an exterior bag.

The individual wrapper must be tightly sealed to prevent the food product from leaking out, drying out, or spoiling, while allowing the food to be removed from the individual wrapper easily. It is preferable to be able to do so (hereinafter also referred to as “easy-openability”).

Peeling forms of easy-open packaging materials in which a sealed portion is peeled include delamination, cohesive delamination, and the like. Regarding easy-open packaging materials, there is a multilayer film provided with a peelable resin layer (Patent Document 1).

JP 2016-43964 A

However, the package described in Patent Document 1 is a multi-layer film package in which a release resin layer and an adhesive resin layer are laminated in contact with each other, and is suitable for applications such as repeated opening and resealing. However, it is not necessarily suitable for use as a package for thin foods or powdered medicines that is not repeatedly opened and resealed. In addition, since the delamination layer of the package of Patent Document 1 is mainly composed of an amide resin, it is expensive and is required when manufacturing applications such as individual packages for sliced cheese and powdered medicines. Processability was not necessarily sufficient, and extrusion lamination during production was not easy.

The present invention advantageously solves the above-mentioned problems, has both practically sufficient sealability and easy-openability, is excellent in productivity at the time of packaging, and furthermore is extrusion-laminated at the time of production as part of a multilayer film. and a method of manufacturing the same.

The present inventors have extensively researched packaging materials suitable for individually packaging thin foods such as sliced cheese and pharmaceuticals such as powders. , a delamination layer, an intermediate layer, and a sealing layer, and by forming an anchor coating agent layer between the delamination layer and the base material layer, a highly preservable sealing property and easy opening are achieved. It has been found that a packaging material having both properties can be obtained.

The packaging material of the present invention based on the above findings comprises an anchor coating agent layer, a delamination layer, an intermediate layer, and a seal layer laminated in this order on one surface side of a base material layer, The delamination layer is polypropylene, the intermediate layer is one or more kinds of polyethylene selected from low-density polyethylene, medium-density polyethylene and high-density polyethylene, and the sealing layer is the package. It is characterized by being used for sealing the side seal portion.

Further, in the packaging material of the present invention, the anchor coating agent layer is a coating layer of an aqueous dispersion containing a polyolefin resin, and the polyolefin resin is a copolymer of a polyolefin component and an unsaturated carboxylic acid component. and the polyolefin component is preferably polypropylene, and the sealing layer is preferably one or two selected from linear low-density polyethylene and low-density polyethylene.

In addition, the packaging material of the present invention can be provided with a water-repellent coating layer and a heat seal layer on the other surface side of the base material layer, and the water-repellent coating layer is made of acrylic copolymer resin, vinyl chloride- One or more resins selected from vinyl acetate copolymer resins, polyester resins, polyurethane resins, chlorinated polyolefin resins, ethylene-vinyl acetate copolymer resins, urea resins, epoxy resins, polyamide resins, and cellulose resins. In particular, the water-repellent coating layer preferably contains a polyamide resin and a nitrocellulose resin. Also, the heat seal layer preferably contains an ethylene-vinyl acetate copolymer.
Furthermore, the packaging material of the present invention is suitable as a packaging material for cheese.

According to the packaging material of the present invention, it is possible to obtain a packaging material having both a sealing property with high preservability and an easy-to-open property.

1 is a schematic cross-sectional view of one embodiment of a packaging material of the present invention; FIG. 1. It is typical sectional drawing of the sealing part of the package using the packaging material of FIG. 1. It is typical sectional drawing which shows the state which the sealing part of the package using the packaging material of FIG. 1 separated. FIG. 4 is a schematic cross-sectional view of another embodiment of the packaging material of the present invention; FIG. 5 is a schematic cross-sectional view of a sealed portion of a package using the packaging material of FIG. 4; 5 is a schematic cross-sectional view showing a state in which the sealed portion of the package using the packaging material of FIG. 4 is separated; FIG. 1 is a plan view of an example of a package using the packaging material of the present invention; FIG.

Hereinafter, embodiments of the packaging material of the present invention will be described in detail with reference to the drawings as an example of packaging cheese.
FIG. 1 shows a schematic cross-sectional view of one embodiment of the packaging material of the present invention. In FIG. 1, the packaging material 1 is made of a multilayer film, and includes a substrate layer 2, an anchor coating agent layer 3, a delamination layer 4, an intermediate layer 5, and a seal layer 6. are laminated in this order on the surface side of the . In the illustrated example, the anchor coating agent layer 3 is formed in contact with the surface 2a of the base material layer 2. As shown in FIG. By providing the delamination layer 4, the packaging material 1 of the present embodiment has excellent easy-openability. In addition, the seal layer 6 is provided to contribute to high sealing performance when side sealing is performed.

FIG. 2 shows a schematic cross-sectional view of the seal part of the package using the packaging material 1 shown in FIG. 1, specifically the side seal part, and FIG. 1 shows a schematic cross-sectional view of a state in which parts are separated; FIG. The sealing portion shown in FIG. 2 is formed by folding a sheet of packaging material 1, overlapping one portion 1a and the other portion 1b with the sealing layers 6 facing each other, and applying heat to form the same type of sealing layer 6. They are sealed by being heat-sealed together. The seal layers 6 of the same kind are heat-sealed to each other to provide a high seal strength, so that the side seal portion has a high sealability when used for individual packages of sliced cheese. In addition, for example, polyethylene suitable for the intermediate layer 5 has relatively low adhesion to the interlayer separation layer 4, for example, a polypropylene layer. As shown, delamination can be performed between the delamination layer 4 and the intermediate layer 5, so that the package using the packaging material 1 can be easily opened. Note that FIG. 3 shows an example of delamination between the delamination layer 4 and the seal layer 6 of the other portion 1b of the packaging material 1, but the delamination layer 4 and the seal layer 6 of the portion 1a are separated. Delamination may also occur between

Each layer will be specifically described below.
[Base material layer]
As the base material layer 2, a resin film that constitutes an ordinary packaging material can be appropriately used. Specifically, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, polyvinyl alcohol, polyacrylonitrile, polycarbonate, ethylene-vinyl acetate copolymer, ionomer, ethylene-(meth)acrylic acid Copolymer, ethylene-(meth)ethyl acrylate copolymer, ethylene-propylene copolymer, methylpentene, polybutene, acid-modified polyolefin resin, polyamide resin, polystyrene resin, low-crystalline saturated polyester or non Crystalline polyester resin, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), tetrafluoroethylene-ethylene copolymer (ETFE), polytetrafluoroethylene (PTFE), MXD6, etc. A film consisting of
Among the resin films listed above, polyester resins such as polyethylene terephthalate (hereinafter also referred to as "PET"), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN); Polyamide resins such as amide (nylon 6), polyhexamethylene adipamide (nylon 66) and poly-p-xylylene adipamide (MXD6 nylon); polyolefin resins such as polyethylene and polypropylene are preferred. In particular, a PET film is more preferable for the substrate layer 2 because of its high transparency, excellent dimensional stability, and excellent heat resistance. The above polyester resins, polyamide resins and polyolefin resins may be mixtures thereof.
The substrate layer 2 may be a multilayer film in which two or more layers of resin films are laminated. In the case of a multilayer film, each layer may have the same composition or different compositions.

These resin films may be non-stretched films, but uniaxially stretched films or biaxially stretched films are preferably used from the viewpoint of transparency and the like. Although the thickness of the film is not particularly limited, it is about 5 to 500 μm, preferably 5 to 300 μm, more preferably 10 to 100 μm.

The base material layer 2 may have a laminated structure in which a barrier layer is further laminated on the above resin film layer. By laminating the barrier layer, it is possible to effectively suppress the weight reduction of the contents and the deterioration of the contents. When the barrier layer is laminated, the water-repellent coating layer 7 and the heat seal layer are provided on the barrier layer side of the substrate layer 2, and the anchor coating agent layer 3, the delamination layer 4 and the seal layer are provided on the resin film layer side. A laminated structure having 6 is preferred. However, the packaging material of the present invention is provided with the anchor coating layer 3, the delamination layer 4 and the seal layer 6 on the barrier layer side of the base material layer 2, and the water-repellent coating layer 7 and the heat seal layer on the resin film layer side. may be used as a laminated structure.

The barrier layer is, for example, a metal foil made of aluminum foil or the like, a vapor deposition film of an inorganic material or an inorganic oxide, a vapor deposition film having the vapor deposition film on a resin film, or an ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyvinyl It may be a layer made of alcohol, a gas barrier resin such as MXD6, or a combination thereof.
In order to ensure the visibility of the food, the barrier layer is preferably transparent, and an inorganic oxide vapor deposition film or an inorganic oxide vapor deposition film obtained by providing the vapor deposition film on a plastic film is particularly preferably used. be done. The inorganic oxide that forms the deposited film may be any inorganic oxide that is transparent and has gas barrier properties against oxygen, water vapor, etc. Examples include aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, oxide Among oxides such as zirconium, titanium oxide, boron oxide, hafnium oxide, and barium oxide, aluminum oxide and silicon oxide are particularly preferred from the viewpoint of gas barrier properties, production efficiency, and the like.

The surface of the base material layer 2 may be subjected to surface treatment for improving wettability, such as corona treatment, ozone treatment, flame treatment, etc., in order to improve adhesiveness. Such a surface treatment can be applied to both the surface on which the anchor coating agent layer 3 is formed and the surface on which the water-repellent coating layer 7 is formed among the surfaces of the base material layer 2, and both surfaces can be treated. is preferred. Moreover, when the base material layer 2 has the barrier layer mentioned above, the surface of this barrier layer can be surface-treated.

[Anchor coating agent layer]
The anchor coating agent layer 3 is a layer having adhesiveness to the substrate layer 2 and adhesiveness to extrusion-laminated polypropylene, which is a specific example of the delamination layer 4 . The anchor coating agent layer 3 is preferably a coating layer of an aqueous dispersion containing a polyolefin resin as an anchor coating agent. The anchor coating agent of the anchor coating agent layer 3 is such that the polyolefin resin is a copolymer of a polyolefin component and an unsaturated carboxylic acid component, and the polyolefin component is polypropylene.

The effect of the packaging material 1 of the present invention having the anchor coating agent layer 3 will be described.
With respect to packaging materials made of multilayer films, when a polypropylene layer and a polyethylene layer are laminated, the adhesive strength between the polypropylene layer and the polyethylene layer is lower than the adhesive strength between similar layers. It is considered that the easy opening property of the packaging material can be obtained by utilizing this low interlayer adhesive strength. However, the polypropylene layer has poor adhesion to the substrate layer that is generally used for packaging materials, and even if a conventionally known urethane-based anchor coating agent is formed on the surface of the substrate layer, the extrusion-laminated polypropylene layer and the As for the substrate layer, the interlayer adhesive strength required for the packaging material was not obtained.

Although it is possible to bond the polypropylene layer and the base layer with an adhesive, so-called dry lamination, the cost is high, and bonding with an adhesive requires a certain thickness of the polypropylene layer. Specifically, a thickness of 20 μm or more is required. A polypropylene layer having such a thickness has difficulty in packaging processing such as bending of a packaging material made of a multilayer film.

Therefore, instead of a polypropylene layer, a polyethylene layer is extrusion-laminated on the base material layer directly or via an anchor coating agent layer, and the polypropylene layer is laminated on the side opposite to the base material layer when viewed from the polyethylene layer. A multi-layer film packaging material having a layer structure of an outermost layer formed by laminating layers on top of each other is conceivable. Since the polyethylene layer has high adhesion to the base material layer, the interlayer adhesive strength necessary for the packaging material can be obtained between the polyethylene layer and the base material layer. However, in such a layer structure, the outermost heat-sealable layer of the laminated film is a polypropylene layer, and the polyethylene layer is arranged on the inner layer side. In a package with a polypropylene layer as a heat seal layer, the melting point of polypropylene is higher than that of polyethylene. It may be difficult to obtain sufficient bonding strength between layers. Therefore, when manufacturing the package, the range of suitable conditions for the heating temperature and heating time during heat sealing is narrow, and it is difficult to increase the line speed of the packaging machine.

In contrast, the packaging material of the present invention comprises an anchor coating agent layer using a specific anchor coating agent containing a copolymer of polypropylene and an unsaturated carboxylic acid component, and the polypropylene component of the anchor coating agent layer and It is compatible with the polypropylene of the extrusion-laminated delamination layer, and can be firmly adhered. Therefore, the extrusion-laminated polypropylene layer and base material layer have the interlayer adhesive strength required for the packaging material. Moreover, by adhering a polypropylene layer having a layer thickness of less than 20 μm, which has been difficult with dry lamination, to the substrate layer via the anchor coating agent layer, it is possible to improve the packaging workability such as bending of the packaging material. Since a polyethylene layer can be used for the outermost seal layer, the preferable range of heating temperature and heating time during heat sealing is wide when manufacturing the package. Furthermore, since delamination can be performed between the polypropylene layer and the outermost layer, such as a polyethylene layer, a stable opening strength can be obtained without depending on the heating temperature and heating time, and the easy opening property is excellent. ing.

The polypropylene of the polyolefin component can be broadly classified into homopolypropylene made of homopolymers, random polypropylene made of random copolymers, and block polypropylene made of block copolymers. From the viewpoint of properties, homopolypropylene and random polypropylene are preferred.

Examples of unsaturated carboxylic acid components include acrylic acid, methacrylic acid, maleic acid and maleic anhydride.

The anchor coating agent of the anchor coating agent layer 3 is an aqueous dispersion containing an acid-modified polypropylene resin and an aqueous medium described in JP-A-2015-163688, wherein the polypropylene component of the acid-modified polypropylene resin is isocratic. An anchor coating agent that is a homopolypropylene having a tactical structure can be used. As the anchor coating agent for the anchor coating agent layer 3, DA-1200 manufactured by Unitika Ltd. can be used as a commercially available product.

The aqueous medium of the aqueous dispersion as the anchor coating agent is water, and may be a liquid containing water as a main component other than water. For example, it may contain a basic compound such as ammonia or an organic solvent. good too.

Additives such as other resins and cross-linking agents can be added to the anchor coating agent in order to further improve the performance depending on the purpose.

Other resins that can be added to the anchor coating agent include, for example, polyurethane resins. By adding a polyurethane resin, it is possible to suppress delamination that may occur at the folds when the contents are stored using the packaging material.

A polymer containing urethane bonds in the main chain can be used as the polyurethane resin. For example, a polymer obtained by reacting a polyol compound and a polyisocyanate compound can be used.

The polyol component that constitutes the polyurethane resin is not particularly limited. ,3-propanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, methyl-1,5-pentanediol, 1,8-octanediol, 2-ethyl-1,3-hexane Low molecular weight glycols such as diols, diethylene glycol, triethylene glycol and dipropylene glycol, low molecular weight polyols such as trimethylolpropane, glycerin and pentaerythritol, polyol compounds having ethylene oxide or propylene oxide units, polyether diols, polyesters Examples include high molecular weight diols such as diols, bisphenols such as bisphenol A and bisphenol F, and dimer diol obtained by converting the carboxyl group of dimer acid to hydroxyl group.

As the polyisocyanate component constituting the polyurethane resin, one or a mixture of two or more known aromatic, aliphatic or alicyclic diisocyanates can be used. Specific examples of diisocyanates include tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate, dimethyl diisocyanate, and lysine diisocyanate. . Moreover, tri- or more functional polyisocyanates such as triphenylmethane triisocyanate and polymethylene polyphenyl isocyanate may be used as diisocyanates.

The amount of the other resin such as the above-described polyurethane resin added is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the copolymer of polypropylene and the unsaturated carboxylic acid component in the aqueous dispersion, and 5 to 100 parts by mass. It is more preferably 60 parts by mass.

Examples of cross-linking agents that can be added to the anchor coating agent include cross-linking agents having self-crosslinking properties, compounds having multiple functional groups in the molecule that react with unsaturated carboxylic acid components, and metals having multivalent coordination sites. etc. can be used.

Specific examples include oxazoline group-containing compounds, carbodiimide group-containing compounds, isocyanate group-containing compounds, epoxy group-containing compounds, melamine compounds, urea compounds, zirconium salt compounds, silane coupling agents, organic peroxides, and the like. You may mix and use several things according to. Among them, oxazoline group-containing compounds, carbodiimide group-containing compounds, isocyanate group-containing compounds, and epoxy group-containing compounds are preferably added from the viewpoint of ease of handling.

The oxazoline group-containing compound is not particularly limited as long as it has at least two oxazoline groups in its molecule. For example, 2,2'-bis(2-oxazoline), 2,2'-ethylene-bis(4,4'-dimethyl-2-oxazoline), 2,2'-p-phenylene-bis(2-oxazoline) , compounds having an oxazoline group such as bis(2-oxazolinylcyclohexane)sulfide, and polymers containing an oxazoline group. These 1 type(s) or 2 or more types can be used. Among these, the oxazoline group-containing polymer is preferable because of its ease of handling.

Oxazoline group-containing polymers are generally obtained by polymerizing addition polymerizable oxazolines such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline and 2-isopropenyl-2-oxazoline. Other monomers may be copolymerized with the oxazoline group-containing polymer, if necessary. A polymerization method for the oxazoline group-containing polymer is not particularly limited, and a known polymerization method can be employed.

The carbodiimide group-containing compound is not particularly limited as long as it has at least two carbodiimide groups in its molecule. For example, compounds having a carbodiimide group such as p-phenylene-bis(2,6-xylylcarbodiimide), tetramethylene-bis(t-butylcarbodiimide), cyclohexane-1,4-bis(methylene-t-butylcarbodiimide) and polycarbodiimide, which is a polymer having carbodiimide groups. These 1 type(s) or 2 or more types can be used. Among these, polycarbodiimide is preferred because of its ease of handling.

The method for producing polycarbodiimide is not particularly limited, and for example, it can be produced by a condensation reaction accompanied by decarbonization of an isocyanate compound. The isocyanate compound is also not limited, and may be aliphatic isocyanate, alicyclic isocyanate, or aromatic isocyanate. The isocyanate compound may be copolymerized with a polyfunctional liquid rubber, polyalkylenediol, or the like, if necessary.

The amount of cross-linking agents such as oxazoline-based cross-linking agents and carbodiimide-based cross-linking agents added is 0.1 to 20 parts by mass with respect to 100 parts by mass of the copolymer of polypropylene and unsaturated carboxylic acid component in the aqueous dispersion. is preferred, and 1 to 10 parts by mass is more preferred.
[Delamination layer]
The material of the delamination layer 4 is preferably polypropylene. By using polypropylene for the delamination layer 4, it can be firmly adhered to the substrate layer 2 under the above-mentioned specific anchor coating agent. Moreover, the sealing layer 6 can be made of polyethylene, which enables delamination while maintaining excellent heat-sealing properties.

Specifically, polypropylene may be homopolypropylene, random polypropylene, block polypropylene, or acid-modified polypropylene. Among polypropylenes, random polypropylene is preferable from the viewpoint of suitability for extrusion lamination. The acid-modified polypropylene is preferably modified with an unsaturated carboxylic acid. Examples of unsaturated carboxylic acids include maleic acid, itaconic acid, fumaric acid, and acrylic acid. Examples of unsaturated carboxylic acid derivatives include maleic anhydride, maleic acid monoester, maleic acid diester, and itaconic acid monoester. , itaconic acid diester, itaconic anhydride, fumaric acid monoester, and fumaric acid diester. Among them, maleic anhydride is preferred because it improves the adhesion of the obtained acid-modified polypropylene to the substrate.
The melt flow rate MFR (230° C., 2.16 kg) of polypropylene used for the delamination layer 4 is preferably 1 to 100 g/10 min, more preferably 3 to 50 g/min.

The layer thickness of the delamination layer 4 can be about 1 to 100 μm. Since the thickness of the delamination layer 4 is in the range of 1 to 100 μm, delamination can be reliably performed with the seal layer 6 to be described later. A thickness of 5 μm is sufficient for the delamination layer 4 , but the thickness can be appropriately reduced to about 100 μm depending on the use of the packaging material of the present invention.

The delamination layer 4 is preferably a layer laminated on the anchor coat agent layer 3 by extrusion lamination, that is, an extrusion lamination layer. Extrusion lamination is a method in which a resin is melted on a base film to form a film, which is then pasted together. Extrusion lamination is preferred because it does not require an adhesive and the thickness of the delamination layer to be laminated can be reduced as compared with the lamination method using an adhesive. For example, it is possible to form a delamination layer having a thickness of less than 20 μm, which cannot be laminated by so-called dry lamination, which is lamination using an adhesive.

As will be described later, the extrusion lamination of the delamination layer 4 is performed by melt co-extrusion with the seal layer 6 to form the delamination layer 4 and the seal layer 6 once on the anchor coating agent layer 3 of the base material layer 2. can be bonded together, which is preferable for improving the productivity of the packaging material 1.

[Middle layer]
The intermediate layer 5 is a layer for delamination from the delamination layer 4 . In the present invention, since the delamination between the intermediate layer 5 and the delamination layer 4 is used for the easy opening of the packaging material 1, the intermediate layer 5 adheres to the polypropylene of the delamination layer 4. It is a layer made of a resin whose adhesion is lower than the adhesion between other layers in the laminated structure of the packaging material of the present invention. Specifically, when the delamination layer 4 is a layer made of polypropylene as described above, the intermediate layer 5 can be a layer made of polyethylene. Among polyethylenes, one or more selected from low-density polyethylene, medium-density polyethylene, and high-density polyethylene can be used from the viewpoint of lower adhesion to polypropylene. Although the thickness of the intermediate layer 5 is not particularly limited, it is preferably about 1 to 100 μm. It is preferably 40 μm or less, more preferably 30 μm or less.

The intermediate layer 5 is preferably a layer laminated on the delamination layer 4 by extrusion lamination, that is, an extrusion lamination layer. Extrusion lamination does not require an adhesive and can reduce the thickness of the sealing layer to be laminated, as compared with the method of laminating using an adhesive. For example, it is possible to form a seal layer having a thickness of less than 20 μm, which cannot be laminated by so-called dry lamination, which is lamination using an adhesive.

The intermediate layer 5 is preferably a layer formed by melt coextrusion with the delamination layer 4 and the sealing layer 6 during extrusion lamination, that is, a melt coextrusion layer. By melt co-extrusion, the delamination layer 4, the intermediate layer 5, and the seal layer 6 can be laminated together on the anchor coating agent layer 3 of the base material layer 2 at once, and the packaging material 1 can be manufactured with good productivity. can be done.

[Seal layer]
The seal layer 6 is a resin layer that can be melted by heat and fused together. In general, resins used for heat sealing include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-(meth) Ethyl acrylate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-propylene copolymer, methylpentene polymer, polyolefin resins (excluding polypropylene) such as polyethylene, acrylic acid, methacrylic acid, maleic anhydride , polyolefin resin modified with unsaturated carboxylic acid such as fumaric acid, ethylene-(meth)acrylic acid ester-unsaturated carboxylic acid terpolymer resin, cyclic polyolefin resin, cyclic olefin copolymer, polyethylene terephthalate (PET ), polyacrylonitrile (PAN), and others. The sealing layer 6 needs to be a material with a lower melting point than the polypropylene of the delamination layer 4 for heat sealing. The seal layer 6 is also required to be non-sticky. Therefore, the sealing layer 6 of the packaging material 1 of the present invention is preferably polyethylene among the resins used for the heat sealing described above. and low-density polyethylene. In the present invention, both the sealing layer 6 and the above-described intermediate layer 5 are layers made of polyethylene. Materials for the sealing layer 6 are selected with emphasis on sealing performance, and materials for the intermediate layer are selected with emphasis on easy-openability. ing. For example, linear low-density polyethylene has higher sealing properties than medium-density polyethylene and high-density polyethylene, but has relatively higher adhesion to polypropylene than low-density polyethylene, medium-density polyethylene, and high-density polyethylene. Therefore, it can be used for the sealing layer 6 . If linear low-density polyethylene is used for the intermediate layer 5, or if linear low-density polyethylene is used for the seal layer 6 without the intermediate layer 5, delamination between the delamination layer 4 is not sufficient, and the easy-openability may not be sufficient. The present invention is not limited to the case where the intermediate layer 5 and the seal layer 6 are made of different types of polyethylene, and a laminated structure in which the intermediate layer 5 is made of low-density polyethylene and the seal layer 6 is made of the same type of low-density polyethylene. can also

Although the thickness of the sealing layer 6 is not particularly limited, it is preferably about 1 to 100 μm. It is preferably 40 μm or less, more preferably 30 μm or less.

The sealing layer 6 is preferably a layer laminated on the intermediate layer 5 by extrusion lamination, that is, an extrusion lamination layer. Extrusion lamination does not require an adhesive and can reduce the thickness of the sealing layer to be laminated, as compared with the method of laminating using an adhesive. For example, it is possible to form a seal layer having a thickness of less than 20 μm, which cannot be laminated by so-called dry lamination, which is lamination using an adhesive.

The seal layer 6 is preferably a layer formed by melt coextrusion with the delamination layer 4 and the intermediate layer 5 during extrusion lamination, that is, a melt coextrusion layer. By melt co-extrusion, the delamination layer 4, the intermediate layer 5, and the seal layer 6 can be laminated together on the anchor coating agent layer 3 of the base material layer 2 at once, and the packaging material 1 can be manufactured with high productivity. can.

FIG. 4 shows a schematic cross-sectional view of another embodiment of the packaging material of the present invention. In FIG. 4, the packaging material 9 is made of a multi-layer film, and includes a substrate layer 2, an anchor coating agent layer 3, a delamination layer 4, an intermediate layer 5, and a seal layer 6. are laminated in this order on the surface side of the . In the illustrated example, the anchor coating agent layer 3 is formed in contact with the surface 2a of the base material layer 2. As shown in FIG.

Further, on the other surface side of the base material layer 2, in other words, on the surface side of the base material layer 2 opposite to the surface of the base material layer 2 in contact with the anchor coating agent layer 3, the water-repellent coating layer 7 and the A heat seal layer 8 is provided. In the illustrated example, a water-repellent coating layer 7 and a heat seal layer 8 are formed on the same surface in contact with the surface 2b of the substrate layer 2, respectively. More specifically, the heat seal layer 8 is partially formed on a predetermined region of the surface 2b of the substrate layer 2, and the region on the surface 2b of the substrate layer 2 where the heat seal layer 8 is formed. A water-repellent coating layer 7 is formed on the other regions.

In comparison with the packaging material 1 shown in FIG. 1, the packaging material 9 of this embodiment shown in FIG. The difference is that a water-repellent coating layer 7 and a heat seal layer 8 are provided on the surface side of the layer 2 . The laminate structure of the surface of the base material layer 2 in contact with the anchor coating agent layer 3 is the same as that of the packaging material 1 shown in FIG. Therefore, in FIG. 4, the same members as those of the packaging material shown in FIG. 1 are denoted by the same reference numerals. description is omitted.

Since the packaging material 9 of the present embodiment includes the anchor coating agent layer 3, the delamination layer 4, the intermediate layer 5, and the sealing layer 6 on one surface side of the base material layer 2, as shown in FIG. Similar to the packaging material shown, it has excellent easy openability and high sealability.
Moreover, the packaging material 9 of the present embodiment has excellent water repellency due to the provision of the water repellent coating layer 7 . Furthermore, by providing the heat-sealing layer 8, the overlapped portion of the film around which the cheese is wound has a high sealing property.

In addition, on the surface 2b of the base material layer 2, a gap is provided between the water-repellent coating layer 7 and the heat-sealing layer 8 in consideration of the application accuracy when forming the water-repellent coating layer 7 and the heat-sealing layer 8. It does not exclude certain structures. Moreover, the water-repellent coating layer 7 does not have to be formed on the surface 2b of the base material layer 2 except for the area that contributes to water repellency as the outer surface of the package.

FIG. 5 shows a schematic cross-sectional view of the seal portion of the package using the packaging material 9 shown in FIG. 4, specifically the side seal portion, and FIG. 1 shows a schematic cross-sectional view of a state in which parts are separated; FIG. The sealing portion shown in FIG. 5 is formed by folding a sheet of packaging material 9, overlapping a portion 9a and another portion 9b with the sealing layers 6 facing each other, and applying heat to form the same type of sealing layer 6. They are sealed by being heat-sealed together. The seal layers 6 of the same kind are heat-sealed to each other to provide a high seal strength, so that the side seal portion has a high sealability when used for individual packages of sliced cheese. In addition, for example, polyethylene suitable for the intermediate layer 5 has a relatively low adhesion to a polypropylene layer for the delamination layer 4. Therefore, while ensuring a practically sufficient sealing property of the package, As shown, delamination can be performed between the delamination layer 4 and the intermediate layer 5, so that the package using the packaging material 9 can be easily opened. 6 shows an example in which the delamination occurs between the delamination layer 4 and the seal layer 6 of the other portion 9b of the packaging material 9, but the delamination layer 4 and the seal layer 6 of the portion 9a are separated. Delamination may also occur between

In addition, as shown in FIG. 6, the outer surface of the package obtained by overlapping the seal layers 6 of the one portion 9a and the other portion 9b of the folded packaging material 9 facing each other is the partial heat seal layer 8. Since the water repellent coating layer 7 is formed except for the region, it has excellent water repellency. Therefore, it is possible to quickly and reliably remove the moisture after cooling in water, for example, in one step of manufacturing individual packages of sliced cheese. When the packaging material 1 is wrapped around the cheese and overlapped, the heat seal layer 8 faces the seal layer 6 at the overlapped portion, so the heat seal layer 8 and the seal layer 6 are brought into contact and heated. Thus, by heat-sealing the two, the center seal portion has a high sealing performance.

[Water-repellent coating layer]
In the packaging material 9 of FIG. 4, the water-repellent coating layer 7 is preferably a layer having excellent adhesion to the base material to be coated and excellent water repellency.
Specifically, the water-repellent coating layer 7 is made of acrylic copolymer resin, vinyl chloride-vinyl acetate copolymer resin, polyester resin, polyurethane resin, chlorinated polyolefin resin, ethylene-vinyl acetate copolymer resin, urea resin. , an epoxy resin, a polyamide resin, and a cellulose-based resin, or a layer formed by blending two or more of them. Cellulose-based resin is preferably nitrocellulose resin.

Among others, the water-repellent coating layer 7 is preferably a blend of a polyamide resin and a cellulose-based resin, and it is particularly preferable that the cellulose-based resin is a nitrocellulose resin. In this case, it is preferable that the polyamide resin is 60 to 80% by mass and the cellulose resin is 20 to 40% by mass. If the polyamide resin content is 80% or less, the water repellency is improved, but if it exceeds 80%, the heat resistance is lowered and post-processing becomes difficult. When the polyamide resin content is 60% or more, the heat resistance is improved, but when it exceeds 60% by mass, the water repellency becomes insufficient. In other words, if the cellulose resin is added too much, the water repellency is lowered, but the heat resistance is improved. If the amount added is small, the water repellency is improved, but the heat resistance is poor.

The water-repellent coating layer 7 is made of the acrylic copolymer resin, vinyl chloride-vinyl acetate copolymer resin, polyester resin, polyurethane resin, chlorinated polyolefin resin, ethylene-vinyl acetate copolymer resin, urea resin, A resin selected from epoxy resins, polyamide resins, and cellulosic resins may be used singly or in a blend of two or more resins, and further polyethylenetetrafluoroethylene particles may be added.

The polyethylenetetrafluoroethylene particles preferably have a volume average particle size of 2 to 5 μm. If the volume average particle diameter is less than 2 μm, the effect of improving water repellency is not sufficiently obtained, and if it exceeds 5 μm, the coatability of the water repellent coating layer 7 is deteriorated. The amount of polyethylenetetrafluoroethylene particles added is preferably 2 to 30 parts by mass with respect to 100 parts by mass of the resin. If it is less than 2 parts by mass, the effect of improving the water repellency cannot be sufficiently obtained, and if it is more than 30 parts by mass, the coatability of the water repellent coating layer 7 is lowered.

[Heat seal layer]
In the packaging material 9 of FIG. 4, the heat seal layer 8 preferably has excellent adhesion to the base material layer 2 to be coated, and blocks when rolled up after printing. Specifically, an ethylene-vinyl acetate copolymer can be used as the heat-sealing agent for the heat-sealing layer 8 . The vinyl acetate content in the ethylene-vinyl acetate copolymer is preferably 20 to 40% by mass. If it is less than 20% by mass, the low-temperature stability is poor, and if it exceeds 40% by mass, the heat seal strength is lowered.

The ethylene-vinyl acetate copolymer used for the heat seal layer 8 may be modified with an unsaturated carboxylic acid and/or its derivative. Examples of unsaturated carboxylic acids include maleic acid, itaconic acid, fumaric acid, and acrylic acid. Examples of unsaturated carboxylic acid derivatives include maleic anhydride, maleic acid monoester, maleic acid diester, and itaconic acid monoester. , itaconic acid diester, itaconic anhydride, fumaric acid monoester, and fumaric acid diester. Among them, maleic anhydride is preferable because it improves the heat resistance of the obtained ethylene-vinyl acetate copolymer resin composition.
The amount of the unsaturated carboxylic acid and/or derivative thereof in the ethylene-vinyl acetate copolymer is preferably 0.01 to 2.0% by mass, since heat resistance is improved.

Moreover, the heat sealing agent of the heat sealing layer 8 preferably contains a polyamide resin in order to prevent blocking. The polyamide resin is a thermoplastic polyamide that can be obtained by polycondensation of an amine and an acid. Examples of the amine include hexamethylenediamine, and examples of the acid include adipic acid and sebacic acid. , Trimellitic anhydride, dimer acid, etc. can be used, and further, those having both amine and acid include 11-aminoundecanoic acid, 12-aminododecanoic acid, etc. Polyamide resins combining these can be used.

[Method for manufacturing packaging material]
Next, a method for manufacturing the packaging material of the present invention will be described. An example of the method for producing the package of the present invention is an aqueous dispersion containing a polyolefin resin on one surface of a substrate, the polyolefin resin being a copolymer of a polyolefin component and an unsaturated carboxylic acid component. and the polyolefin component is propylene. After applying and drying an anchor coating agent layer to form an anchor coating agent layer, a delamination layer and a layer are formed on the surface of the anchor coating agent layer by melt coextrusion , and the seal layer are laminated in that order at once. In addition, in the packaging material shown in FIG. 4, a water-repellent coating agent and a heat-sealing agent are applied separately on the other surface of the substrate to form a water-repellent coating layer and a heat-sealing layer, respectively. .

As the anchor coating agent layer, a known coating method can be used to apply the anchor coating agent already described. After coating, the aqueous medium is evaporated by drying treatment to obtain an anchor coating agent layer. The drying conditions are not particularly limited, but may be appropriately selected within the range of a heating temperature of 40 to 200° C. and a heating time of 1 to 600 seconds.
The amount of the anchor coating agent to be applied is preferably 0.001 to 5 g/m ² in dry mass of the anchor coating agent with respect to the coated surface. Sufficient adhesiveness can be obtained economically when the amount of the anchor coating agent is in the range of 0.001 to 5 g/m ² .

The delamination layer can be formed on the anchor coat agent layer by extrusion lamination. Also, the sealing layer can be formed on the delamination layer by extrusion lamination. In particular, it is preferable to simultaneously form the delamination layer and the sealing layer on the anchor coating agent layer by melt co-extrusion. As a result, the packaging material of the present invention can be produced with high productivity, and the layer thickness of the delamination layer and the seal layer can be made thinner than in the method of sticking together by dry lamination. Thin layer thicknesses of the delamination layer and the sealing layer can improve the bending workability when the package is produced by enclosing the contents in the packaging material.

The water-repellent coating layer is formed by applying a varnish containing the above resin or a varnish obtained by adding polyethylenetetrafluoroethylene particles to the surface of the substrate layer by an appropriate coating method such as gravure printing or silk screen printing. be able to. It is preferable to subject the surface of the substrate layer to surface treatment such as corona treatment, ozone treatment, and flame treatment before coating.

The heat-sealing layer can be formed by applying a varnish containing the above-mentioned heat-sealing agent to the surface of the substrate layer by an appropriate coating method such as gravure printing or silk screen printing. It is preferable to subject the surface of the substrate layer to surface treatment such as corona treatment, ozone treatment, and flame treatment before coating.

The heat-seal layer is partially formed on the surface of the base material layer in the heat-sealed region of the package. Such partial formation can be performed by an appropriate coating method such as gravure printing or silk screen printing as described above. The above-described water-repellent coating layer is formed on the surface of the base material layer other than the heat seal layer. The separate coating of the heat-seal layer and the water-repellent coating layer on the surface of the base material layer can also be performed by an appropriate coating method such as gravure printing or silk screen printing.

[Package]
The packaging material of the present invention is heat-sealed, is required to be easy to open, and can be used for applications in which it is immersed in water during the packaging process, and the contents are not particularly limited. For example, it is suitable for packaging thin foods such as sliced cheese and seaweed. FIG. 7 shows a plan view of an example of a package 10 in which sliced cheese as a content is packaged with the packaging material of the present invention. In the packaging body 10 shown in the figure, the packaging material 1 covers the back surface of the sliced cheese 11 having a rectangular plane, is folded back at two opposite sides of the sliced cheese 11, and is wound so as to overlap on the surface of the sliced cheese 11. The heat seal layer 8 and the seal layer 6 are brought into contact with each other and heat-sealed between the overlapping margins L between one end 10a and the other end 10b opposite thereto, thereby center-sealing. FIG. 7 illustrates the center-sealed center seal portion 10c. In addition, the sealing layers 6 of the two overlapping packaging materials 1 are heat-sealed at the ends of the other two opposing sides of the sliced cheese 11 . FIG. 7 shows the side seal portion 10d. Since the sealing layer 6 of the packaging material 1 of the present invention is made of polyethylene, the sealing of the side sealing portions 11b can be performed stably at high speed.

EXAMPLES The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[Example 1]
A polyolefin anchor coating agent (DA-1010J2, manufactured by Unitika Ltd.) was coated on the corona surface of a PET film (E-5100 manufactured by Toyobo Co., Ltd.) having a thickness of 12 μm, one side of which was corona-treated as a substrate layer. ℃ to form an anchor coating agent layer. On the surface of this anchor coating agent layer, polypropylene (F329RA, manufactured by Prime Polymer Co., Ltd.) having a thickness of 5 μm as a delamination layer, high-density polyethylene (HF560, Japan Polyethylene Co., Ltd.) having a thickness of 3 μm as an intermediate layer, and a seal layer were formed. A linear low-density polyethylene (KC570S, Japan Polyethylene Co., Ltd.) having a thickness of 4 μm was melt-coextruded at 290° C. to obtain a laminate of Example 1.
[Example 2]
Example 2 is an example in which the material of the intermediate layer is different from Example 1. FIG.
A polyolefin anchor coating agent (DA-1010J2, manufactured by Unitika Ltd.) was coated on the corona surface of a PET film (E-5100 manufactured by Toyobo Co., Ltd.) having a thickness of 12 μm, one side of which was corona-treated as a substrate layer. ℃ to form an anchor coating agent layer. On the surface of this anchor coating agent layer, polypropylene (F329RA, manufactured by Prime Polymer Co., Ltd.) having a thickness of 5 μm as a delamination layer, low density polyethylene (LC522, Japan Polyethylene Co., Ltd.) having a thickness of 3 μm as an intermediate layer, and a seal layer were formed. A laminate of Example 2 was obtained by melt-coextrusion of linear low-density polyethylene (KC570S, Japan Polyethylene Co., Ltd.) having a thickness of 4 μm at 290°C.

[Comparative Example 1]
Comparative Example 1 is an example in which the material of the intermediate layer is different from that of Example 1.
A polyolefin anchor coating agent (DA-1010J2, manufactured by Unitika Ltd.) was coated on the corona surface of a PET film (E-5100 manufactured by Toyobo Co., Ltd.) having a thickness of 12 μm, one side of which was corona-treated as a substrate layer. ℃ to form an anchor coating agent layer. Polypropylene (F329RA, manufactured by Prime Polymer Co., Ltd.) with a thickness of 5 μm and a linear low-density polyethylene (KC570, Japan Polyethylene Co., Ltd.) with a thickness of 3 μm as an intermediate layer were formed on the surface of this anchor coating agent layer. , a linear low-density polyethylene (KC570S, Nippon Polyethylene Co., Ltd.) having a thickness of 4 μm as a seal layer was melt coextruded at 290° C. to obtain a laminate of Comparative Example 1.

[Comparative Example 2]
Comparative Example 2 is an example in which the material of the intermediate layer is different from that of Example 1.
A polyolefin anchor coating agent (DA-1010J2, manufactured by Unitika Ltd.) was coated on the corona surface of a PET film (E-5100 manufactured by Toyobo Co., Ltd.) having a thickness of 12 μm, one side of which was corona-treated as a substrate layer. ℃ to form an anchor coating agent layer. On the surface of this anchor coating agent layer, a random polypropylene (F329RA, manufactured by Prime Polymer Co., Ltd.) having a thickness of 5 μm as a delamination layer, a random polypropylene (F329RA, manufactured by Prime Polymer Co., Ltd.) having a thickness of 3 μm as an intermediate layer, and a seal A laminate of Comparative Example 2 was obtained by melt-coextrusion of linear low-density polyethylene (KC570S, Japan Polyethylene Co., Ltd.) having a thickness of 4 μm as a layer at 290°C.

<Seal strength measurement>
In order to measure the seal strength of the region corresponding to the side seal portion of the packaging material of the laminates of Examples 1 and 2 and Comparative Examples 1 and 2, each laminate sample was placed so that the heat seal layer was on the inside. After folding, the heat-sealed layers were brought into contact with each other and sealed at various temperatures from 110°C to 180°C in increments of 10°C for 1 second under pressure of 1 kgf/cm ² . The strength of the seal portion was measured according to JIS K6854 under the conditions of 25° C. atmosphere and tensile speed of 50 mm/min, and the state of peeling was observed. It can be said that the seal strength is good if it is in the range of 1.6 to 2.8 N/15 mm. Table 1 shows the results.

From Table 1, in Examples 1 and 2, peeling occurred between the interlayer peeling layer and the intermediate layer even at a low temperature.

<Filling test>
Using a packaging and filling machine (FP2000 manufactured by natec), the packaging material of the laminate of each example and each comparative example was filled with cheese melted at 80°C to prepare a package. When the package was produced, side sealing was performed under two conditions, 400 rpm and 1000 rpm, for the number of revolutions of the seal bar of the apparatus. A higher number of rotations means a higher production speed of the package. The sealing temperature of the side seal was 150°C.
After the packaging and filling, the side seal portion of each package was cut into strips having a width of 15 mm, and the interlaminar adhesive strength was measured in accordance with JIS K6854 at a tensile rate of 50 mm/min under an atmosphere of 25°C. Moreover, the peeling form of the peeled laminate after the test was confirmed.
Table 2 shows the results. The unit of seal strength in the table is N/15 mm.

From Table 2, in Examples 1 and 2, high sealing strength and easy opening due to delamination were obtained.
On the other hand, in Comparative Examples 1 and 2, cohesive peeling occurred on the seal surface when the rotation speed of the seal bar was high.

Although the packaging material of the present invention has been specifically described above with reference to the embodiments and examples, the packaging material of the present invention is not limited to the description of these embodiments and examples. Many modifications are possible without departing from the above. For example, the packaging material of the present invention is not limited to cheese, but can be used for foods other than cheese, and also for packaging other than foods, such as pharmaceutical powders.

Reference Signs List 1, 9 Packaging material 2 Base material layer 3 Anchor coating agent layer 4 Delamination layer 5 Intermediate layer 6 Sealing layer 7 Water-repellent coating layer 8 Heat sealing layer

Claims (8)

An anchor coating agent layer, a delamination layer, an intermediate layer, and a seal layer are laminated in this order on one surface side of the base material layer,
The delamination layer is polypropylene,
The intermediate layer is one or more types of polyethylene selected from low-density polyethylene, medium-density polyethylene and high-density polyethylene. the law of nature,
The seal layer is used for sealing the side seal portion when the package is formed. A packaging material characterized by The anchor coating agent layer is a coating layer of an aqueous dispersion containing a polyolefin resin, the polyolefin resin being a copolymer of a polyolefin component and an unsaturated carboxylic acid component, and the polyolefin component comprising: The packaging material according to claim 1, which is polypropylene. 3. The packaging material according to claim 1, wherein said sealing layer is one or two types of polyethylene selected from linear low-density polyethylene and low-density polyethylene. The packaging material according to any one of claims 1 to 3, comprising a water-repellent coating layer and a heat seal layer on the other surface side of the base material layer. The water-repellent coating layer is made of acrylic copolymer resin, vinyl chloride-vinyl acetate copolymer resin, polyester resin, polyurethane resin, chlorinated polyolefin resin, ethylene-vinyl acetate copolymer resin, urea resin, epoxy resin, polyamide. 5. The packaging material according to claim 4, which contains one or more resins selected from resins and cellulose resins. The packaging material according to claim 4 or 5, wherein the water-repellent coating layer contains a polyamide resin and a nitrocellulose resin. The packaging material according to any one of claims 4 to 6, wherein the heat seal layer contains an ethylene-vinyl acetate copolymer. The packaging material according to any one of claims 1 to 7, which is a packaging material for cheese.

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