JP6988327B2 - Packaging material - Google Patents

Description

The present invention relates to a packaging material. More specifically, the present invention relates to a packaging material that can easily open a package containing foods, pharmaceuticals, and the like.

Plastic film packaging materials are used for filling and packaging foods such as cheese, ham, sausage, kamaboko, yokan, and jelly, and for packaging pharmaceuticals such as powder. For example, sliced cheese obtained by molding processed cheese into a sheet having a thickness of about several mm and a size of about 10 cm square is directly and individually wrapped with a plastic film, and a plurality of individual packages are packaged. It is sold in a form in which it is stacked and housed in a pillow-shaped packaging bag.

An individual package of such food will be described with the example of a sliced cheese packaging material. An example of a conventional sliced cheese packaging material is a laminated plastic film having 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 section of the filling machine, pulled out in the longitudinal direction, and while continuously moving at a predetermined line speed, both ends of the sliced cheese packaging material in the lateral direction are pulled and stacked. The overlapped parts are center-sealed to form a cylinder. After injecting melted processed cheese into this cylindrical internal space, it is 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 sandwiching the openings at both ends in the longitudinal direction of the film, and heat-sealing the sealing layers located on the inner surface of the film in close contact with each other (side seal). After sealing, it is passed through water to cool and solidify the processed cheese of the contents. After cooling and solidifying, the moisture on the packaging surface is removed using air and a brush. After that, it is cut into a predetermined size to make an individual package, and a plurality of individual packages are stacked and packed in an outer bag.

The process of removing water from the surface of the package is to avoid problems due to water in the subsequent process of stacking a plurality of individual packages, and to fill the outer bag at high speed, thereby improving the efficiency of the packaging process. Therefore, it is desired to reliably remove the moisture on the packaging surface in a shorter time.

Therefore, regarding the packaging material for cheese that focuses on the water repellency of the surface, the propylene resin water repellent is applied to the outer surface side of the film base material on the entire surface, and the propylene-ethylene copolymer or the like is applied to the inner surface side of the film base material. (Patent Document 1).

Japanese Unexamined Patent Publication No. 10-101174

However, the cheese package described in Patent Document 1 has a low sealing property in order to ensure that the food can be easily opened when it is taken out from the individual package (hereinafter, also referred to as "easy-opening property"). Since it is a packaging material and is sealed with a strength such that the heat-sealed portion can be easily peeled off when the cheese is taken out from the cheese package, the sealing property of the cheese is low. In addition, the overlapped portion of the film around which the cheese was wrapped was not sealed and was simply overlapped, so that the sealing property of the cheese was also low in this respect as well. Therefore, after the cheese package described in Patent Document 1 was taken out from the outer bag having a gas barrier property and opened, the cheese was dried and deteriorated quickly, and the storage period was not long.

The present invention advantageously solves the above-mentioned problems, and has both highly storable sealing properties and easy-opening properties, and further has water repellency on the surface and is excellent in productivity at the time of packaging. The purpose is to provide materials.

As a result of intensive research on packaging materials suitable for individually packaging thin foods such as sliced cheese and pharmaceuticals such as powder, the present inventors have conducted intensive research on a water-repellent coat layer on one side of the base material layer. And a heat seal layer are provided in parallel on one surface, and an anchor coating agent layer, a delamination layer and a seal layer are provided on the other side of the base material layer, and between the delamination layer and the base material layer. In addition, it has been found that by forming the anchor coating agent layer, a packaging material having both a highly storable sealing property and an easy-to-open property and further having a water-repellent surface can be obtained.

The packaging material of the present invention based on the above findings is provided with an anchor coating agent layer, a delamination layer, and a sealing layer laminated in this order on one surface side of the base material layer, and the base material is provided. A water-repellent coat layer and a heat-seal layer are provided on the other surface side of the layer, and the water-repellent coat layer and the heat-seal layer are partially formed on the same surface of the base material layer. It is characterized by.

In the packaging material of the present invention, the water-repellent coat layer is an acrylic copolymer resin, a vinyl chloride-vinyl acetate copolymer resin, a polyester resin, a polyurethane resin, a chlorinated polyolefin resin, an ethylene-vinyl acetate copolymer resin, and the like. It is preferable to contain one kind or two or more kinds of resins selected from urea resin, epoxy resin, polyamide resin and cellulose resin, and it is more preferable to contain polyamide resin and nitrocellulose resin.

Further, in the packaging material of the present invention, the heat seal layer preferably contains an ethylene-vinyl acetate copolymer, and the anchor coating agent layer is a coating layer of an aqueous dispersion containing a polyolefin resin. The polyolefin resin is preferably a copolymer of a polyolefin component and an unsaturated carboxylic acid component, and the polyolefin component is preferably polyethylene, and the delamination layer is preferably polyethylene, and the seal layer. However, it is preferable that the polyethylene is one or more of low-density polyethylene, linear low-density polyethylene, medium-density polyethylene and high-density polyethylene.
Further, the packaging material of the present invention is suitable as a packaging material for cheese.

According to the packaging material of the present invention, a packaging material having both high storage stability and easy-opening property and excellent water repellency can be obtained.

It is a schematic sectional drawing of one Embodiment of the packaging material of this invention. It is a schematic cross-sectional view of the seal part of the package body using the packaging material of FIG. FIG. 3 is a schematic cross-sectional view showing a state in which the sealed portion of the package using the packaging material of FIG. 1 is separated. It is a top view of an example of the packaging body using the packaging material of this invention.

Hereinafter, embodiments of the packaging material of the present invention will be specifically described with reference to drawings in an example of packaging cheese.
FIG. 1 shows a schematic cross-sectional view of an embodiment of the packaging material of the present invention. In FIG. 1, the packaging material 1 is made of a multilayer film, and the base material layer 2, the anchor coating agent layer 3, the delamination layer 4, and the seal layer 5 are provided on one surface side of the base material layer 2. It is provided by stacking in this order. In the illustrated example, the anchor coating agent layer 3 is formed in contact with the surface 2a of the base material layer 2. By providing the delamination layer 4, the packaging material 1 of the present embodiment has excellent easy-to-open properties. Further, the seal layer 5 is provided, which contributes to high sealing performance when performing side sealing.

Further, on the other surface side of the base material layer, in other words, on the surface side of the base material layer 2 on the side opposite to the surface of the base material layer 2 in contact with the anchor coating agent layer 3, the water repellent coat layer 6 and the heat. The seal layer 7 is provided. In the illustrated example, the water-repellent coat layer 6 and the heat seal layer 7 are formed on the same surface in contact with the surface 2b of the base material layer 2, respectively. More specifically, a region in which the heat seal layer 7 is partially formed in a predetermined region on the surface 2b of the base material layer 2 and the heat seal layer 7 is formed on the surface 2b of the base material layer 2. The water-repellent coat layer 6 is formed in a region other than the above. By providing the water-repellent coat layer 6, the packaging material 1 of the present embodiment has excellent water repellency. Further, by providing the heat-sealing layer 7, the packaging material 1 of the present embodiment contributes to a high sealing property of the overlapped portion of the film on which the cheese is wrapped.

In addition, on the surface 2b of the base material layer 2, there is a gap between the water-repellent coat layer 6 and the heat-seal layer 7 in consideration of coating accuracy when forming the water-repellent coat layer 6 and the heat-seal layer 7. It does not exclude certain structures. Further, the water-repellent coat layer 6 does not have to form a region other than the region contributing to water repellency as the outer surface of the package on the surface 2b of the base material layer 2.

FIG. 2 shows a schematic cross-sectional view of a sealed portion of a package using the packaging material 1 shown in FIG. 1, specifically, a side seal portion, and FIG. 3 shows the seal when the package of FIG. 2 is opened. A schematic cross-sectional view showing a state in which the portions are separated is shown. In the sealing portion shown in FIG. 2, one packaging material 1 is folded back and a part 1a and another part 1b are overlapped with each other facing each other, and heat is applied to the sealing layer 5 of the same type. It is sealed by heat-sealing each other. The sealing strength due to heat fusion between the sealing layers 5 of the same type is high, so that the side sealing portion has a high sealing property when used for an individual package of sliced cheese. Further, for example, polyethylene, which is suitable as the sealing layer 5, has a relatively low adhesion to, for example, the polypropylene layer as the delamination layer 4, so that while ensuring sufficient sealing performance for practical use of the package, FIG. 3 shows. As shown, delamination can be performed between the delamination layer 4 and the seal layer 5, and by extension, the package using the packaging material 1 can be easily opened. Although FIG. 3 shows an example in which delamination is performed between the delamination layer 4 and the seal layer 5 of the other portion 1b of the packaging material 1, the delamination layer 4 and the seal layer 5 of the partial 1a are shown. Delamination may occur between the layers.

Further, as shown in FIG. 2, the outer surface of the package in which the seal layers 5 of the partially folded portion 1a and the other portion 1b are overlapped with each other facing each other is the partial heat seal layer 7. Since the water-repellent coat layer 6 is formed except for the region, it has excellent water repellency. Therefore, for example, the water content after cooling in water in one step during the production of individual packages of sliced cheese can be quickly and surely removed. Further, when the packaging material 1 is wound around the cheese and overlapped with the heat seal layer 7, the heat seal layer 7 faces the seal layer 5 at the overlapped portion, so that the heat seal layer 7 and the seal layer 5 are brought into contact with each other for heating. As a result, the center seal portion has a high sealing property by heat-sealing and sealing the two.

Hereinafter, each layer will be specifically described.
[Base layer]
As the base material layer 2, a resin film constituting a normal 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. Polymers, ethylene-ethyl ethyl acrylate copolymers, ethylene-propylene copolymers, methylpentene, polybutene, acid-modified polyolefin resins, polyamide resins, polystyrene resins, low crystalline saturated polyester or non-polymers Crystalline polyester resin, polyvinylidene chloride (PVC), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), tetrafluoroethylene-ethylene copolymer (ETFE), polytetrafluoroethylene (PTFE), MXD6, etc. A film consisting of can be used.
Among the above-mentioned resin films, polyester resins such as polyethylene terephthalate (hereinafter, also referred to as “PET”), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polybutylene naphthalate (PBN); polycapron. Polyethylene resins such as amide (nylon 6), polyhexamethylene adipamide (nylon 66), poly-p-xylylene adipamide (MXD6 nylon); polyolefin resins such as polyethylene and polypropylene are preferred. In particular, the PET film is more preferable for the base material layer 2 because it has high transparency, excellent dimensional stability, and excellent heat resistance. The above-mentioned polyester resin, polyamide resin and polyolefin resin may be a mixture thereof.
The base material layer 2 may be a multilayer film in which two or more resin films are laminated. In the case of a multilayer film, each layer may have the same composition or may have a different composition.

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. The thickness of the film is not particularly limited, but is about 5 to 500 μm, preferably 5 to 300 μm, and 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 layers are laminated, the water-repellent coat layer 6 and the heat seal layer are provided on the barrier layer side of the base material layer 2, and the anchor coat agent layer 3, the delamination layer 4 and the seal layer are provided on the resin film layer side. A laminated structure in which 5 is provided is preferable. However, in the packaging material of the present invention, the anchor coating agent layer 3, the delamination layer 4 and the sealing layer 5 are provided on the barrier layer side of the base material layer 2, and the water repellent coating layer 6 and the heat sealing layer are provided on the resin film layer side. It may be a laminated structure provided with.

The barrier layer may be, for example, a metal foil made of an aluminum foil or the like, a vapor-deposited film of an inorganic substance or an inorganic oxide, a vapor-deposited film having the vapor-deposited film on a resin film, an ethylene-vinyl alcohol copolymer, polyvinylidene chloride, or polyvinyl chloride. 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 food, the barrier layer is preferably transparent, and an inorganic oxide-deposited film or an inorganic oxide-deposited film having the vapor-filmed film provided on a plastic film is particularly preferably used. Will be done. The inorganic oxide forming the vapor-deposited film may be any inorganic oxide having transparency and gas barrier properties such as oxygen and water vapor, for example, aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, and oxidation. Oxides such as zirconium, titanium oxide, boron oxide, hafnium oxide, and barium oxide are preferably used. In particular, aluminum oxide and silicon oxide are preferably used 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 such as corona treatment, ozone treatment, frame treatment, etc. to improve wettability in order to improve the adhesiveness. Such surface treatment can be applied to any of the surfaces of the base material layer 2 on which the anchor coating agent layer 3 is formed and the surface on which the water-repellent coating layer 6 is formed, and is applied to both surfaces. Is preferable. Further, when the base material layer 2 has the above-mentioned barrier layer, the surface of the barrier layer can be surface-treated.

[Anchor coating agent layer]
The anchor coating agent layer 3 is a layer having an adhesiveness to the base material layer 2 and a property of being able to adhere to extruded polypropylene as 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. In the anchor coating agent of the anchor coating agent layer 3, 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 including the anchor coating agent layer 3 will be described.
When a polypropylene layer and a polyethylene layer are laminated with respect to a packaging material made of a multilayer film, the adhesive strength between the polypropylene layer and the polyethylene layer becomes 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 adhesion strength. However, the polypropylene layer has poor adhesion to the base material layer generally used for packaging materials, and even if a conventionally known urethane-based anchor coating agent is formed on the surface of the base material layer, the polypropylene layer is extruded and laminated. With the base material layer, the interlayer adhesive strength required for the packaging material could not be obtained.

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

Therefore, the polyethylene layer, not the polypropylene layer, is extruded and laminated to the base material layer directly or through the anchor coating agent layer, and the polypropylene layer is laminated on the surface opposite to the base material layer when viewed from the polyethylene layer. It is conceivable that a packaging material for a multilayer film having a layer structure in which the film is laminated to form the outermost layer. Since the polyethylene layer has high adhesion to the base material layer, the interlayer adhesive strength required for the packaging material can be obtained between the polyethylene layer and the base material layer. However, in such a layer structure, the heat seal layer on the outermost surface of the laminated film becomes a polypropylene layer, and the polyethylene layer is arranged on the inner layer side thereof. In a package in which a polypropylene layer is used as a heat-sealed layer, the melting point of polypropylene is higher than that of polyethylene. Therefore, depending on the heating conditions during heat-sealing, the polyethylene layer on the inner layer side may melt first and delamination may be difficult, or polypropylene may be difficult to delaminate. In some cases, it may be difficult to obtain sufficient bonding strength between the layers. Therefore, at the time of manufacturing the package, the optimum range of the heating temperature and the heating time at the time of heat sealing is narrow, and it is difficult to increase the line speed of the packaging machine.

On the other hand, 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. , The polypropylene of the delamination layer that has been extruded and laminated is compatible with each other and can be firmly adhered. Therefore, the polypropylene layer and the base material layer that have been extruded and laminated can obtain the interlayer adhesive strength required for the packaging material. Further, by adhering a polypropylene layer having a layer thickness of less than 20 μm, which was difficult with dry laminating, to the base material layer via the anchor coating agent layer, it is possible to improve packaging processability such as bending of the packaging material. Since a polyethylene layer can be used as the outermost sealing layer, a range of suitable conditions for the heating temperature and heating time at the time of heat sealing is wide at the time of manufacturing the package. Further, since the polypropylene layer and the outermost layer, for example, a polyethylene layer, can be delaminated, stable opening strength can be obtained without depending on the heating temperature and heating time, and the opening property is excellent. ing.

Polypropylene as a polyolefin component can be roughly divided into homopolypropylene made of a homopolymer, random polypropylene made of a random copolymer, and block polypropylene made of a block copolymer. Adhesion between the base material layer 2 and the extruded laminated polypropylene as the delamination layer 4 described later. From the viewpoint of sex, homopolypropylene and random polypropylene are preferable.

Examples of the unsaturated carboxylic acid component include acrylic acid, methacrylic acid, maleic acid, maleic anhydride and the like.

The anchor coating agent of the anchor coating agent layer 3 is an aqueous dispersion containing the acid-modified polypropylene resin described in JP-A-2015-163688 and an aqueous medium, and the polypropylene component of the acid-modified polypropylene resin is an iso. An anchor coating agent which 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 in addition to water, and contains, for example, a basic compound such as ammonia or an organic solvent. May be good.

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 the polyurethane resin, it is possible to suppress the delamination that may occur in the crease portion when the contents are stored using the packaging material.

As the polyurethane resin, a polymer containing a urethane bond in the main chain can be used, and for example, a polymer obtained by reacting a polyol compound with a polyisocyanate compound can be used.

The polyol component constituting the polyurethane resin is not particularly limited, and for example, water, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,2-propanediol, 1 , 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 glycols, triethylene glycols and dipropylene glycols, low molecular weight polyols such as trimethylolpropane, glycerin and pentaerythritol, polyol compounds having ethylene oxide and propylene oxide units, polyetherdiols and polyesters. Examples thereof include high-molecular-weight diols such as diols, bisphenols such as bisphenol A and bisphenol F, and dimer diols obtained by converting the carboxyl group of dimer acid into a hydroxyl group.

Further, as the polyisocyanate component constituting the polyurethane resin, one or a mixture of two or more known diisocyanates belonging to aromatics, aliphatics or alicyclics can be used. Specific examples of diisocyanates include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,3-phenylenediocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 1,5-naphthalenedi isocyanate, isophorone diisocyanate, dimethyl diisocyanate, and lysine diisocyanate. , Hydrous 4,4'-diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, dimerging isocyanate obtained by converting the carboxyl group of dimer acid into an isocyanate group, and adducts, biurets, isocyanurates and the like thereof. Further, as the diisocyanates, trifunctional or higher polyisocyanates such as triphenylmethane triisocyanate and polymethylene polyphenyl isocyanate may be used.

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

The cross-linking agent that can be added to the anchor coating agent includes a cross-linking agent having a self-cross-linking property, a compound having a plurality of functional groups reacting with an unsaturated carboxylic acid component in the molecule, and a metal having a multivalent coordination constellation. Etc. can be used.

Specific examples thereof 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, which are necessary. A plurality of compounds may be mixed and used depending on the above. Above all, from the viewpoint of ease of handling, it is preferable to add an oxazoline group-containing compound, a carbodiimide group-containing compound, an isocyanate group-containing compound, and an epoxy group-containing compound.

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

The oxazoline group-containing polymer is generally obtained by polymerizing an addition-polymerizable oxazoline 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. The polymerization method of the oxazoline group-containing polymer is not particularly limited, and a known polymerization method can be adopted.

The carbodiimide group-containing compound is not particularly limited as long as it has at least two or more carbodiimide groups in the molecule. For example, compounds having a carbodiimide group such as p-phenylene-bis (2,6-kisilylcarbodiimide), tetramethylene-bis (t-butylcarbodiimide), cyclohexane-1,4-bis (methylene-t-butylcarbodiimide). And polycarbodiimide which is a polymer having a carbodiimide group can be mentioned. One or more of these can be used. Among these, polycarbodiimide is preferable 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 involving decarbonization of an isocyanate compound. The isocyanate compound is also not limited, and may be any of an aliphatic isocyanate, an alicyclic isocyanate, and an aromatic isocyanate. The isocyanate compound may be copolymerized with a polyfunctional liquid rubber, a polyalkylene diol, or the like, if necessary.

The amount of the cross-linking agent added such as the oxazoline-based cross-linking agent and the carbodiimide-based cross-linking agent is 0.1 to 20 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. It is preferably 1 to 10 parts by mass, and more preferably 1 to 10 parts by mass.
[Delamination layer]
The material of the delamination layer 4 is preferably polypropylene. By using polypropylene as the delamination layer 4, it is possible to firmly adhere to the base material layer 2 under the above-mentioned specific anchor coating agent. Further, the sealing layer 5 can be made of polyethylene, and delamination is possible while maintaining excellent heat-sealing properties.

Specifically, the polypropylene may be homopolypropylene, random polypropylene, block polypropylene, or acid-modified polypropylene. Random polypropylene is particularly preferable as the polypropylene from the viewpoint of suitability for extrusion laminating. The acid-modified polypropylene is preferably modified to an unsaturated carboxylic acid. Examples of the unsaturated carboxylic acid include maleic acid, itaconic acid, fumaric acid, and acrylic acid, and examples of the derivative of the unsaturated carboxylic acid include maleic anhydride, maleic acid monoester, maleic acid diester, and itaconic acid monoester. , Itaconic acid diester, anhydrous itaconic acid, fumaric acid monoester, fumaric acid diester and the like. Among them, maleic anhydride is preferable because the adhesiveness of the obtained acid-modified polypropylene to the substrate is improved.
The polypropylene melt flow rate MFR (230 ° C., 2.16 kg) 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. When the delamination layer 4 is in the range of 1 to 100 μm, delamination can be reliably performed between the delamination layer 4 and the seal layer 5 described later. The delamination layer 4 has a sufficient thickness as long as 5 μm, but can be appropriately made up 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 coating agent layer 3 by extrusion laminating, that is, an extrusion laminating layer. Extrusion laminating is a method in which a resin is melted into a film and bonded to a base film. The extruded laminate is preferable because it does not require an adhesive and the thickness of the delamination layer to be bonded can be reduced as compared with the method of bonding using an adhesive. For example, it is possible to form a delamination layer having a thickness of less than 20 μm, which cannot be bonded by so-called dry laminating, which is bonded using an adhesive.

As will be described later, in the extrusion lamination of the delamination layer 4, the delamination layer 4 and the seal layer 5 are once put on the anchor coating agent layer 3 of the base material layer 2 by melt coextrusion with the seal layer 5. Can be bonded together, which is preferable for improving the productivity of the packaging material 1.

[Seal layer]
The seal layer 5 is a resin layer that can be melted by heat and fused to each other. Generally, the resins used for heat sealing include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear (linear) low-density polyethylene, ethylene-vinyl acetate copolymer, ionomer resin, and ethylene- (meth). Polyethylene-based resins (excluding polypropylene) such as ethyl acrylate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene-propylene copolymer, methylpentene polymer, and polyethylene are used as acrylic acid, methacrylic acid, and maleic anhydride. , Fumaric acid and other unsaturated carboxylic acid-modified polyolefin resins, ethylene- (meth) acrylic acid ester-unsaturated carboxylic acid ternary copolymer resin, cyclic polyolefin resin, cyclic olefin copolymer, polyethylene terephthalate (PET) ), Polyacrylonitrile (PAN), etc., one or more resins can be used. In the present invention, since the delamination between the seal layer 5 and the delamination layer 4 is used for the easy opening of the packaging material 1, the adhesion of the delamination layer 4 with polypropylene is the present invention. It is necessary that the adhesiveness between other layers in the laminated structure of the packaging material is lower than that of polypropylene, and that the material has a lower melting point than polypropylene of the delamination layer 4 for heat sealing. Further, the seal layer 5 is also required to be non-sticky. Therefore, as the seal layer 5 of the packaging material 1 of the present invention, polyethylene is preferable among the resins used for the above-mentioned heat seal, specifically, low density polyethylene, linear low density polyethylene, medium density polyethylene and high density polyethylene. One type of density polyethylene or two or more types of polyethylene can be mentioned. More preferably, it is low density polyethylene or linear low density polyethylene.

The thickness of the seal layer 5 is not particularly limited, but is preferably about 1 to 100 μm. It is preferably 40 μm or less, more preferably 30 μm or less.

The seal layer 5 is preferably a layer laminated on the anchor coating agent layer 3 by extrusion laminating, that is, an extrusion laminating layer. The extruded laminate does not require an adhesive as compared with the method of bonding using an adhesive, and the thickness of the sealing layer to be bonded can be reduced. For example, it is possible to form a seal layer having a thickness of less than 20 μm, which cannot be bonded by so-called dry laminating, which is bonded using an adhesive.

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

[Water repellent coat layer]
The water-repellent coat layer 6 is preferably a layer having excellent adhesion to the substrate to be coated and having excellent water repellency.
Specifically, the water-repellent coat layer 6 includes an acrylic copolymer resin, a vinyl chloride-vinyl acetate copolymer resin, a polyester resin, a polyurethane resin, a chlorinated polyolefin resin, an ethylene-vinyl acetate copolymer resin, and a urea resin. , One of the resins selected from the epoxy resin, the polyamide resin, and the cellulose-based resin can be used alone, or two or more of them can be blended to form a layer. The cellulosic resin is preferably a nitrocellulose resin.

The water-repellent coat layer 6 is preferably a blend of a polyamide resin and a cellulosic resin, and particularly preferably the cellulosic resin is a nitrocellulose resin. In this case, the polyamide resin is preferably 60 to 80% by mass, and the cellulosic resin is preferably 20 to 40% by mass. When the polyamide resin is 80% or less, the water repellency is improved, but when it exceeds 80%, the heat resistance is lowered and post-processing becomes difficult. When the polyamide resin is 60% or more, the heat resistance is improved, but when it exceeds 60% by mass, the water repellency becomes insufficient. That is, if the cellulosic 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 inferior.

The water-repellent coat layer 6 includes the acrylic copolymer resin, vinyl chloride-vinyl acetate copolymer resin, polyester resin, polyurethane resin, chlorinated polyolefin resin, ethylene-vinyl acetate copolymer resin, and urea resin. One of the resins selected from the epoxy resin, the polyamide resin, and the cellulose-based resin may be used alone or in combination of two or more thereof, and polyethylene tetrafluoroethylene particles may be further added.

The polyethylene tetrafluoroethylene particles preferably have a volume average particle size of 2 to 5 μm. If the volume average particle size is less than 2 μm, the water repellency improving effect cannot be sufficiently obtained, and if it exceeds 5 μm, the coatability of the water repellent coat layer 6 is lowered. The amount of polyethylene tetrafluoroethylene 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 water repellency cannot be sufficiently obtained, and if it is more than 30 parts by mass, the coatability of the water-repellent coat layer 6 is lowered.

[Heat seal layer]
The heat seal layer 7 preferably has excellent adhesion to the base material layer 2 to be coated and is blocked when rolled up after printing. Specifically, an ethylene-vinyl acetate copolymer can be used as the heat-sealing agent for the heat-sealing layer 7. 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 inferior, and if it exceeds 40% by mass, the heat seal strength is lowered.

The ethylene-vinyl acetate copolymer used for the heat seal layer 7 may be modified with an unsaturated carboxylic acid and / or a derivative thereof. Examples of the unsaturated carboxylic acid include maleic acid, itaconic acid, fumaric acid, and acrylic acid, and examples of the unsaturated carboxylic acid derivative include maleic anhydride, maleic acid monoester, maleic acid diester, and itaconic acid monoester. , Itaconic acid diester, anhydrous itaconic acid, fumaric acid monoester, fumaric acid diester and the like. Among them, maleic anhydride is preferable because the heat resistance of the obtained ethylene-vinyl acetate copolymer resin composition is improved.
The amount of the unsaturated carboxylic acid and / or its derivative in the ethylene-vinyl acetate copolymer is preferably 0.01 to 2.0% by mass because the heat resistance is improved.

Further, the heat sealant of the heat seal layer 7 preferably contains a polyamide resin in order to prevent blocking. The polyamide resin is a thermoplastic polyamide obtained by polycondensing an amine and an acid, and as the amine, for example, hexamethylenediamine can be used, and as the acid, for example, adipic acid and sebacic acid. , Anhydrous trimellitic acid, dimer acid and the like can be used, and further, there are 11-aminoundecanoic acid, 12-aminododecanoic acid and the like having both amine and acid, and a polyamide resin in which these are combined can be used. Can be used.

[Manufacturing method of packaging materials]
Next, a method for producing the packaging material of the present invention will be described. An example of the method for producing a package of the present invention is an aqueous dispersion containing a polyolefin resin on one surface of a base material, wherein the polyolefin resin is a copolymer of a polyolefin component and an unsaturated carboxylic acid component. An anchor coating agent whose polyolefin component is propylene is applied and dried to form an anchor coating agent layer, and then a delamination layer is formed on the surface of the anchor coating agent layer by melt copolymerization. , The seal layer and the seal layer are laminated at once in that order to form. Further, the water-repellent coating agent and the heat-sealing agent are separately applied on the other surface of the base material to form a water-repellent coating layer and a heat-sealing layer, respectively.

As the method for applying the anchor coating agent already described as the anchor coating agent layer, a known coating method can be used. After coating, the aqueous medium is evaporated by a drying treatment to obtain an anchor coating agent layer. The drying conditions are not particularly limited, but may be appropriately selected in 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 applied is preferably ^{0.001 to 5 g / m 2} in terms of the dry mass of the anchor coating agent on the coated surface. Sufficient adhesiveness can be economically obtained 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 coating agent layer by extrusion laminating. Further, the seal layer can be formed on the delamination layer by extrusion laminating. In particular, it is preferable to simultaneously form the delamination layer and the seal layer on the anchor coating agent layer by melt coextrusion. Thereby, the packaging material of the present invention can be produced with high productivity, and the layer thickness can be made thinner than the method in which the delamination layer and the seal layer are brought into close contact with each other by dry laminating. The thin layer thickness of the delamination layer and the seal layer can improve the bending workability when the contents are enclosed in the packaging material to manufacture the package.

The water-repellent coat layer is formed by applying a varnish containing the above resin or a varnish containing polyethylene tetrafluoroethylene particles added to the surface of the base material layer by an appropriate coating method such as gravure printing or silk screen printing. be able to. It is preferable that the surface of the base material layer is subjected to surface treatment such as corona treatment, ozone treatment, and frame treatment before coating.

The heat seal layer can be formed by applying a varnish containing the heat sealant to the surface of the base material layer by an appropriate coating method such as gravure printing or silk screen printing. It is preferable that the surface of the base material layer is subjected to surface treatment such as corona treatment, ozone treatment, and frame treatment before coating.

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

[Packaging]
The packaging material of the present invention is sealed with a heat seal, is required to be easy to open, and can be used for applications in which it is immersed in water in the packaging process, and the content is not particularly limited. For example, it is suitable for packaging thin foods such as sliced cheese and seaweed. FIG. 4 shows a plan view of an example of a package 10 in which sliced cheese is packaged with the packaging material of the present invention as a content. In the packaging material 10 shown in the figure, the packaging material 1 covers the back surface of the sliced cheese 11 having a rectangular flat surface, is folded back on 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 7 and the seal layer 5 are brought into contact with each other and heat-sealed between the overlap margin L between one end portion 10a and the other end portion 10b facing the same end portion 10a to be center-sealed. FIG. 4 illustrates the center-sealed center seal portion 10c. Further, at the ends of the two opposite sides of the sliced cheese 11, the seal layers 5 of the two overlapping packaging materials 1 are heat-sealed. FIG. 4 illustrates the side seal portion 10d. Since the sealing layer 5 of the packaging material 1 of the present invention is polyethylene, the side sealing portion 11b can be sealed at high speed and stably.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[Example 1]
A water-repellent coat layer (MFG) is coated with a water-repellent agent composed of a polyamide resin and a nitrocellulose resin on one side of a 12 μm-thick PET film (manufactured by E-5200 Toyo Spinning Co., Ltd.) whose both sides are corona-treated as a base material layer. Cheese varnish 3 Toyo Ink Co., Ltd.) is partially formed, and a heat sealant of ethylene-vinyl acetate copolymer system (Seikadyne SC-D (NT), large) is formed in the region where the water-repellent coat layer is not formed on the same surface. Nisseika Kogyo Co., Ltd.) was coated with a thickness of 1 μm to form a heat seal layer. Next, a polyolefin-based anchor coating agent (DA-1010J2, manufactured by Unitika Ltd.) was coated on the surface of the base material layer opposite to the surface on which the water-repellent coat layer and the heat seal layer were formed, and dried at 100 ° C. To form an anchor coating agent layer. On the surface of this anchor coating agent layer, polypropylene (F329RA, manufactured by Prime Polymer Co., Ltd.) with a thickness of 8 μm as a delamination layer and linear low-density polyethylene (KC570S, manufactured by Japan Polyethylene Corporation) as a sealing layer with a thickness of 4 μm. Was melt-coextruded at 290 ° C. to obtain the laminate of Example 1.

[Comparative Example 1]
A water-repellent coat layer (MFG) is coated with a water-repellent agent composed of a polyamide resin and a nitrocellulose resin on a 16 μm non-heat-sealed surface of a PET film (Dycel Value Coating Co., Ltd., MS-01) having a sealing property as a base material layer. Cheese Wanis 3 Toyo Ink Co., Ltd.) is partially formed, and an ethylene-vinyl acetate copolymer heat sealant (Seikadyne SC-D (NT), large) is formed in a region where a water-repellent coat layer is not formed on the same surface. Nisseika Kogyo Co., Ltd.) was coated with a thickness of 1 μm to form a heat-sealed layer, and a laminate of Comparative Example 1 was obtained.

<Filling test>
Using a packaging filling machine (FP2000 manufactured by natec), cheese-filled packaging materials melted at 80 ° C. were prepared in the packaging materials of the laminates of Example 1 and Comparative Example 1. When producing the package, side-sealing was performed under two conditions of the rotation speed of the seal bar of the apparatus being 400 rpm and 1000 rpm. The higher the number of revolutions, the higher the production speed of the package. The sealing temperature of the side seal was 150 ° C.

<Water repellency evaluation>
Regarding the water repellency of each package after packing, 0.1 ml of water droplets are dropped on a JIS P8147 friction angle measuring machine, and the angle at which the water droplets slide off when tilted is measured, and the angle is (20 degrees) or less. Was good.

<Measurement of seal strength>
The side seal portion of each package after packing was cut into strips having a width of 15 mm, and the interlayer adhesive strength was measured in an atmosphere of 25 ° C. at a tensile speed of 50 mm / min according to JIS K6854. In addition, the peeled morphology of the peeled laminate after the test was confirmed.
Table 1 shows the results of water repellency evaluation and seal strength measurement for Example 1 and Comparative Example 1. The unit of seal strength is N / 15 mm.

From Table 1, in Example 1, not only the water repellency was excellent, but also the sealing strength of the side seal portion was high, and the peeling was peeled between polypropylene and polyethylene, and the seal was easy to open.
On the other hand, in Comparative Example 1, although the water repellency was excellent, the sealing strength of the side seal portion was low, so that the sealing property was low. It did not have sufficient ease of opening.

<Preservation test>
The packages of Example 1 and Comparative Example 1 were stored at room temperature for 3 days, and the state of cheese was confirmed. The results are shown in Table 2.

From Table 2, in Example 1, since the sealing property of the sealed portion was high, the cheese did not dry. On the other hand, in Comparative Example 1, the sealing property of the sealed portion was poor, and there was a problem that the cheese dried.

Although the packaging material of the present invention has been specifically described above using the embodiments and examples, the packaging material of the present invention is not limited to the description of these embodiments and examples, and the gist of the present invention is used. Many deformations are possible within the range that does not deviate from. For example, the packaging material of the present invention is not limited to cheese, and can be used for foods other than cheese, and also for packaging such as powders of pharmaceuticals other than foods.

1 Packaging material 2 Base material layer 3 Anchor coating agent layer 4 Delamination layer 5 Seal layer 6 Water repellent coating layer 7 Heat seal layer

Claims (8)

An anchor coating agent layer, a delamination layer, and a sealing layer are laminated in this order on one surface side of the base material layer, and a water-repellent coating layer is provided on the other surface side of the base material layer. And with a heat seal layer,
The water repellent coating layer and the heat seal layer, on the same surface of the base layer, the packaging material characterized that you have been respectively partially formed. The water-repellent coat layer is an 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. The packaging material according to claim 1, which comprises one kind or two or more kinds of resins selected from resins and cellulose-based resins. The packaging material according to claim 1, wherein the water-repellent coat layer contains a polyamide resin and a nitrocellulose resin. The packaging material according to any one of claims 1 to 3, wherein the heat-sealing layer contains an ethylene-vinyl acetate copolymer. The anchor coating agent layer is a coating layer of an aqueous dispersion containing a polyolefin resin, the polyolefin resin is a copolymer of a polyolefin component and an unsaturated carboxylic acid component, and the polyolefin component is. The packaging material according to any one of claims 1 to 4, which is polypropylene. The packaging material according to any one of claims 1 to 5, wherein the delamination layer is polypropylene. The packaging material according to any one of claims 1 to 6, wherein the sealing layer is one or more kinds of polyethylene such as low density polyethylene, linear low density polyethylene, medium density polyethylene and high density polyethylene . The packaging material according to any one of claims 1 to 7, which is a packaging material for cheese.

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