JP2022160832A - Laminate and packaging material - Google Patents

Abstract

To provide a laminate capable of comparatively inexpensively producing a packaging material usable for a food product and difficult to adhere specifically for a solid content having adhesiveness, and also to provide a packaging material using the same.SOLUTION: A laminate includes a transparent substrate layer 1, a printed layer 2, an adhesion layer 3 and a sealant layer 7 in this order. The sealant layer 7 is an embossed film with irregularities applied to an entire thickness thereof. A contact area at a sealant surface of the laminate to the content is 50% or less of the total area.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a laminate and a packaging material using the same, and more particularly to a laminate capable of producing a packaging material to which solid sticky contents are less likely to adhere.

BACKGROUND ART Various packaging materials such as packaging bags are widely manufactured using laminates obtained by laminating synthetic resin films. There are various properties required for packaging materials, one of which is that the contents are difficult to adhere to and easy to take out.

The liquid-repellent sealant film described in Patent Document 1 is a sealant film that can sufficiently prevent the contents from adhering even when containing contents containing a large amount of surfactant such as liquid detergent. This sealant film is a liquid-repellent sealant film characterized by including a heat-adhesive resin layer containing a fluorine-based additive in its layer structure, and the fluorine-based additive bleeding out onto the surface of the sealant film. be.

The liquid-repellent sealant film described in Patent Document 1 is effective for contents such as liquid detergents, but cannot be used as a packaging material for food to which additives cannot be added. It is. In addition, there is a problem that the fluorine-based additive that bleeds out to the surface may impair the heat-sealing property.

The liquid-repellent sealant film described in Patent Document 2 is a liquid-repellent sealant that has a property to prevent adhesion to contents such as yoghurt, a gas barrier property, and a printed image that can be clearly seen from the inner surface side. It's a film.

The liquid-repellent sealant film described in Patent Document 2 is a liquid-repellent sealant film in which a gas barrier substrate, a printing ink film, a sealant layer, and an adhesion prevention layer are laminated in this order, and a metal foil or A liquid-repellent sealant film comprising a metal deposition layer and containing fine particles having an average secondary particle diameter of 100 nm to 100 μm in the anti-adhesion layer.

The liquid-repellent sealant film described in Patent Document 2 can be used for food, but it was developed as a lid material for yogurt on which a printed image indicating the winning or losing of a prize was formed. It can only be used for very limited special applications. In addition, there is an inherent risk that fine particles will fall off and be mixed with the contents.

The packaging material described in Patent Document 3 is intended to prevent the liquid contents from adhering, to take out in a shorter time, and to prevent the contents from remaining, and the use of additives The purpose of this invention is to solve conventional problems such as falling off of fine particles and the like. This packaging material is a packaging material having on its inner surface protruded or recessed streaks extending in a zigzag manner parallel to the opening.

The packaging material described in Patent Document 3 has zigzag-shaped ridges or grooves on the inner surface, and requires a special processing method. It is inevitable. In addition, since the purpose is to facilitate the outflow of highly viscous liquid contents, the effect cannot be expected for solid, sticky contents.

JP 2018-178005 A Japanese Patent Application Laid-Open No. 2019-31015 Japanese Patent No. 6690292

The problem to be solved by the present invention is to provide a laminate that can be used for food, and that can be produced relatively inexpensively as a packaging material that is particularly resistant to the adhesion of solid sticky contents, and the use of the laminate. We propose a packaging material that

As a means for solving the above problems, the invention according to claim 1 is a laminate having a transparent substrate layer, a printing layer, an adhesive layer, and a sealant layer in this order, wherein the sealant layer has a full thickness The laminate is an embossed film having unevenness over the entire area, and the laminate is characterized in that the contact area of the sealant surface of the laminate with respect to the contents is 50% or less of the total area.

The laminate according to the present invention has unevenness on the surface of the sealant layer by using an embossed film having unevenness over the entire thickness as the sealant layer, which is the surface with which the contents come into contact. As a result, the contact area with the content is reduced, making it easier to take out the solid sticky content.

Further, the invention according to claim 2 is a laminate having a transparent substrate layer, a printing layer, an adhesive layer, a gas barrier layer, an adhesive layer, and a sealant layer in this order, wherein the sealant layer is The laminate is an embossed film having unevenness, and is characterized in that the area of contact with the contents on the sealant surface of the laminate is 50% or less of the total area.

Further, the invention according to claim 3 is the laminate according to claim 1 or 2, wherein the adhesive layer in contact with the sealant layer is a melt-extruded adhesive resin layer.

Further, the invention according to claim 4 is characterized in that the embossed shape of the embossed film is a pattern in which unit shapes such as rhombuses, squares, hexagons, and circles are continuous. or 1 item|term is a laminated body.

Further, the invention according to claim 5 is a packaging material obtained by placing the sealant layers of the laminate according to any one of claims 1 to 4 facing each other and heat-sealing the peripheral edges.

The laminate according to the present invention uses an embossed film having unevenness over the entire thickness as the sealant layer, so that the contact area of the sealant surface of the laminate with the contents is 50% or less of the total area. . For this reason, the packaging material using this laminate has the effect of being less sticky to contents that are solid and have sticky surfaces, making it easier to take out of the bag.

As in the second aspect of the invention, when the gas barrier layer is included in the layer structure, the storage stability of the contents is further enhanced.

As in the invention according to claim 3, when a melt-extruded adhesive resin layer is used as the adhesive layer in contact with the sealant layer, the unevenness of the surface of the sealant layer after the adhesive treatment is easily retained compared to dry lamination, and the unevenness loss can be minimized.

As in the invention described in claim 4, when the embossed shape of the embossed film is a pattern in which unit shapes such as rhombuses, squares, hexagons, and circles are continuous, existing commercially available embossed films can be used. . In this case, there is no need to incur the expense of creating a new custom-made embossing roll, which contributes to a reduction in the total cost.

FIG. 1 is a schematic cross-sectional view showing the layer structure in one embodiment of the laminate according to the present invention. FIG. 2 is a cross-sectional explanatory view showing how the contact area with the contents is reduced when the laminate according to the present invention is used as a packaging material. FIG. 3 is a schematic plan view showing an example of an embossed film used as a sealant layer in the laminate according to the present invention. FIG. 4 is a schematic cross-sectional view showing the AA′ cross section of the embossed film of FIG. FIG. 5 is a schematic plan view showing another example of an embossed film used as a sealant layer in the laminate according to the present invention. FIG. 6 is a schematic plan view showing another example of the embossed film used as the sealant layer in the laminate according to the present invention. FIG. 7 is a schematic plan view showing another example of the embossed film used as the sealant layer in the laminate according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION A laminate and a packaging material using the laminate according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the layer structure in one embodiment of the laminate according to the present invention. FIG. 2 is a cross-sectional explanatory view showing how the contact area with the contents is reduced when the laminate according to the present invention is used as a packaging material.

A laminate 10 according to the present invention is a laminate having a transparent substrate layer 1, a printed layer 2, an adhesive layer 5, and a sealant layer 7 in this order, and the sealant layer 7 imparts unevenness over the entire thickness. The laminate is an embossed film, and the laminate is characterized in that the contact area of the sealant surface of the laminate with respect to the contents 30 is 50% or less of the total area.

In the example shown in FIGS. 1 and 2, the adhesive layer 3 and the gas barrier layer 4 are inserted between the printed layer 2 and the adhesive layer 5, and the adhesive layer 5 is the melt extruded adhesive resin layer 6. FIG. The gas barrier layer 4 suppresses the permeation of water vapor and oxygen, and although it is not essential, it can be expected to have the effect of enhancing the storage stability of the contents.

As the transparent substrate layer 1, a transparent synthetic resin film having printability is used. Specifically, a polyethylene terephthalate resin (PET) film with a thickness of 9 to 25 μm, an oriented polypropylene resin (OPP) film with a thickness of 15 to 50 μm, an oriented nylon (ONY) film with a thickness of 15 to 25 μm, etc. are preferably used. be done.

Since the printed layer 2 is printed on the back surface of the transparent base material layer 1, it is printed on the reverse side, so that the left and right patterns are reversed. The ink used for printing is appropriately selected according to the material of the transparent substrate layer 1 and the printing method. The printing method is not particularly limited, and in addition to general gravure printing, printing methods such as flexographic printing, offset printing, and screen printing can be used.

In the example shown in FIG. 1, a gas barrier layer 4 is used, and the printed layer 2 and the gas barrier layer 4 are adhered by an adhesive layer 3 . Although the gas barrier layer 4 is not essential, it has the effect of further increasing the storage stability of the contents because it suppresses permeation of oxygen and water vapor.

As the gas barrier layer 4, a polyvinylidene chloride film, a polyvinyl alcohol film, an ethylene-vinyl alcohol copolymer film, a gas barrier nylon film, a gas barrier polyethylene terephthalate (PET) film or the like, or a PET film or the like containing aluminum or the like is used. A metal-deposited metal film, an inorganic oxide-deposited film obtained by vapor-depositing an inorganic oxide such as aluminum oxide or silicon oxide on a PET film, a polyvinylidene chloride coating, or a coating containing a water-soluble resin and an inorganic layered compound. A gas barrier coating layer such as a resin layer formed by reacting a metal alkoxide or a hydrolyzate thereof with an isocyanate compound, or a metal foil such as an aluminum foil can be used.

As the adhesive layer 3 in this case, an adhesive for dry lamination can be used. As the sealant layer 7, an embossed film having unevenness over the entire thickness is used. An embossed film is made by heating and softening a flat film and pressing it against an embossing roll that has embossed surfaces to form embossments, or by pressing a molten thermoplastic resin against an embossing roll to impart embossing. , was created in any way.

Since embossing rolls generally require a large amount of money and time to manufacture, the use of commercially available embossing films is often advantageous in terms of total cost and lead time in manufacturing. The material of the embossed film may be any material that is commonly used for sealant layers of packaging materials. Specifically, low density polyethylene resin (LDPE), medium density polyethylene resin (MDPE), linear low density polyethylene resin (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-α olefin copolymer , Ethylene-based resins such as ethylene-methacrylic acid resin copolymers, blended resins of polyethylene and polybutene, homopolypropylene resins (PP), propylene-ethylene random copolymers, propylene-ethylene block copolymers, propylene- A polypropylene-based resin such as an α-olefin copolymer can be used.

In FIG. 1, as a method of bonding the sealant layer 7 having unevenness over the entire thickness and the gas barrier layer 4, there is a method of using a melt extruded adhesive resin layer 6 in addition to general dry lamination. . Generally, in the laminating operation, since heat and pressure are applied, the unevenness of the embossed film is reduced to some extent.

Even with the dry lamination method, it is possible to reduce unevenness by increasing the amount of adhesive applied, but there is a limit to the amount of residual solvent that can cause odor problems. be. In this respect, the use of the melt extruded adhesive resin layer 6 as the adhesive layer 5 is more advantageous than the dry lamination adhesive in terms of preventing the unevenness of the embossed film from being reduced.

As the melt extruded adhesive resin layer 6, in addition to the most common low density polyethylene resin (LDPE) and linear low density polyethylene resin (LLDPE), medium density polyethylene resin (MDPE), high density polyethylene resin (HDPE), Polypropylene resin (PP) or the like can also be used.

When the melt extruded adhesive resin layer 6 is used as the adhesive layer 5, an anchor coat (A
Application of agent C) is effective in terms of increasing adhesive strength (laminate strength). A laminate strength of 100 g/15 mm or more is required. Ideally it is 500g/15mm.

When the gas barrier layer is not used as the structure of the laminate 10 , the back surface of the printed layer 2 and the embossed film 7 as the sealant layer are directly laminated by the adhesive layer 5 . The adhesive layer in this case is also the same as in the case where the gas barrier layer is present.

FIG. 2 is a cross-sectional explanatory view showing how the contact area with the contents 30 is reduced when the laminate 10 according to the present invention is used as the packaging material 20. As shown in FIG. Since the embossed film is used as the sealant layer, unevenness remains on the sealant layer surface, which is the inner surface of the packaging material 20. As a result, the contact area with the contents 30 is reduced to less than 100%.

As schematically shown in FIG. 2, the content 30 and the sealant layer 7 are mainly in contact with the protrusions 8 and are not in contact with the recesses 9, so the contact area is reduced from 100%.

If the contact area of the sealant surface of the laminate 10 with respect to the contents 30 is 50% or less of the total area, the adhesion between the packaging material 20 and the contents 30 is reduced, and various contents can be taken out. It turned out to be easier.

FIG. 3 is a schematic plan view showing an example of the embossed film 7 used as the sealant layer in the laminate according to the present invention. FIG. 4 is a schematic cross-sectional view showing the AA′ cross section of the embossed film of FIG. In this example, rhombuses are arranged in order to form a pattern. The colored portions in FIG. 3 are the convex portions 8 and the uncolored portions are the concave portions 9 .

The embossed film shown in FIG. 3 is a commercially available embossed film called Hishikinume, with a material thickness of 50 μm and a total thickness including embossing of 166 μm. Note that in FIG. 4, the thickness of the film is exaggerated.

FIG. 5 is a schematic plan view showing another example of the embossed film 7 used as the sealant layer in the laminate according to the present invention. An example of this is a commercially available embossed film called DIA, in which vertically long rhombuses are arranged in an orderly pattern. Similarly, the thickness of the material is 50 μm, and the total thickness including embossing is 120 μm.

FIG. 6 is a schematic plan view showing another example of the embossed film 7 similarly used as the sealant layer in the laminate according to the present invention. An example of this is a commercially available embossed film called tortoiseshell, in which oblong hexagons are arranged in an orderly pattern. In this example, the thickness of the material is also 50 μm and the total thickness including embossments is 233 μm.

The embossed film used in the laminate of the present invention is not limited to these. For example, as in the example shown in FIG.

Due to the presence of unevenness in the sealant layer 7, when the sealant layers of the laminate 10 are opposed to each other and the peripheral edges are heat-sealed to create a packaging bag, compared to the case where the sealant layer is usually flat, Its seal strength tends to decrease. In response to this, it is necessary to take measures to prevent the reduction in seal strength by raising the sealing conditions.

The required seal strength is 300 g/15 mm or more, preferably 1000 g/15 mm or more.

The laminate 10 according to the present invention is not limited to a general packaging bag obtained by placing the sealant layers 7 facing each other and heat-sealing the peripheral edges, but can be used as various packaging materials by taking advantage of its releasability. is possible. EXAMPLES The laminate and packaging material according to the present invention will be described in more detail below based on examples.

<Example 1>
A polyethylene terephthalate (PET) resin film having a thickness of 12 μm was used as a transparent substrate layer, and a printed layer was formed on the back surface in the opposite direction. This printed surface and an aluminum foil having a thickness of 7 μm were laminated together by extrusion lamination using a polyethylene resin to form an intermediate laminate. The thickness of the polyethylene resin at this time is 15 μm.

Next, an embossed film (linear low-density polyethylene resin, thickness 50 μm, rhombic silk texture) in which embossing is previously formed as shown in FIG. 3 is used as a sealant layer, and the aluminum foil surface of the intermediate laminate, A laminate was obtained by laminating with a polyethylene resin extrusion laminate having a thickness equivalent to 20 μm.

<Example 2>
A laminate was prepared in the same manner as in Example 1, except that an embossed film (linear low-density polyethylene resin, thickness 50 μm, diamond) with embossing previously formed as shown in FIG. 5 was used as the sealant film. did.

<Example 3>
A laminate was prepared in the same manner as in Example 1, except that an embossed film (linear low-density polyethylene resin, thickness 50 μm, tortoise shell) in which embossing was previously formed as shown in FIG. 6 was used as the sealant film. did.

Adhesive foods were placed on the sealant surfaces of the laminates of Examples 1 to 3, and adhesion was evaluated. Moreover, when a packaging bag was produced by placing two laminates facing each other and sealing the peripheral edges, there was no problem in sealing suitability.

1... Transparent substrate layer 2... Printing layer 3... Adhesive layer 4... Gas barrier layer 5... Adhesive layer 6... Melt extruded adhesive resin layer 7... Sealant layer (embossed film )
8... Convex part 9... Concave part 10... Laminated body 20... Packaging material 30... Contents

Claims (5)

A laminate having a transparent substrate layer, a printed layer, an adhesive layer, and a sealant layer in this order, wherein the sealant layer is an embossed film having unevenness over the entire thickness, and the content on the sealant surface of the laminate A laminate characterized in that the contact area with respect to is 50% or less of the total area. A laminate having a transparent substrate layer, a printing layer, an adhesive layer, a gas barrier layer, an adhesive layer, and a sealant layer in this order, wherein the sealant layer is an embossed film having unevenness over the entire thickness, and the laminate A laminate, wherein the contact area with the contents on the sealant surface of is 50% or less of the total area. 3. The laminate according to claim 1, wherein the adhesive layer in contact with the sealant layer is a melt extruded adhesive resin layer. The laminate according to any one of claims 1 to 3, wherein the embossed shape of the embossed film is a pattern in which unit shapes such as rhombuses, squares, hexagons, and circles are continuous. A packaging material obtained by facing the sealant layers of the laminate according to any one of claims 1 to 4 and heat-sealing the peripheral edges.

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