JP7133264B2 - Heat seal film, packaging material, and method for manufacturing packaging material - Google Patents

Description

TECHNICAL FIELD The present invention relates to heat seal films, packaging materials, and methods of making packaging materials.

A heat seal film having a heat seal layer is used in various applications such as food packaging. In general, a heat-sealing film is heat-sealed by pressing a heat-sealing bar against the layered portion of the heat-sealing film from the side opposite to the heat-sealing layer and heating the layer. As described above, in the conventional heat-sealing film, the portion against which the heat-sealing bar is pressed becomes a heat-sealing treatment area, and the heat-sealing layer side is uniformly heat-sealed (thermally welded). It is not easy to heat seal in any pattern in the area. As a means for heat-sealing in a pattern, for example, patterning a heat-seal layer or patterning a portion heated by a heat-seal bar can be considered, but these means have the problem of complicating the process and configuration. be.

JP 2005-292328 A

The present invention has been made to solve the above conventional problems, and its main object is to provide a heat-seal film capable of heat-sealing any region with a simple structure, and such a heat-seal film. It is to provide a packaging material used and a method for manufacturing the packaging material.

The heat seal film of the present invention has a base layer and a heat seal layer laminated on one side of the base layer, and a printed layer is provided on the surface of the heat seal layer opposite to the base layer. and a non-printing region where no printing layer is formed.
In one embodiment, the heat-sealed area has the printed area and the non-printed area.
In one embodiment, a heat-sensitive recording layer is laminated on the opposite side of the base material layer to the heat seal layer and contains a coloring material that develops color when heated.
In one embodiment, the base layer and the thermosensitive recording layer are transparent.
In one embodiment, the heat seal film has a rectangular shape, and the non-printing regions are formed along opposite ends.
In one embodiment, it has a circular or elliptical shape, and the print area and the non-print area are formed along the edges.
According to another aspect of the invention, a packaging material is provided. This packaging material has a container and the heat seal film as a band seal for the container.
In one embodiment, the packaging material has a container and the heat seal film as a top seal for the container.
According to another aspect of the present invention, a method of manufacturing a packaging material is provided. This method for manufacturing a packaging material is a method for manufacturing a packaging material using the heat-seal film, in which a region including the printed region and the non-printed region is heated at the edge of the heat-seal film. and heat-sealing the heat-seal layer in the non-printing areas without heat-sealing the heat-sealing layer in the print areas.

1 is a schematic cross-sectional view of a heat seal film according to one embodiment of the invention; FIG. 1 is a schematic diagram showing a process of heat sealing a heat seal film according to one embodiment of the present invention; FIG. 1 is a schematic plan view of a heat seal film according to one embodiment of the invention; FIG. FIG. 4 is a schematic plan view of a heat seal film according to another embodiment of the invention; 1 is a schematic diagram of a packaging material according to one embodiment of the present invention; FIG. FIG. 4 is a schematic perspective view of a packaging material according to another embodiment of the invention;

Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

A. Heat Seal Film FIG. 1 is a schematic cross-sectional view of a heat seal film according to one embodiment of the present invention. As shown in FIG. 1 , the heat seal film 100 has a base layer 10 and a heat seal layer 20 laminated on one side of the base layer 10 . Furthermore, the heat seal film 100 has a printed region 31 in which the printed layer 30 is formed and a non-printed region 32 in which the printed layer 30 is not formed on the surface of the heat seal layer 20 opposite to the base layer 10. have That is, in the heat seal film 100 , the heat seal layer 20 is exposed in the non-printed area 32 and the heat seal layer 20 is not exposed in the printed area 31 . Thus, when the heat seal film 100 is heat-sealed, the non-printing area 32 is heat-sealed and the printing area 31 is not heat-sealed. The position and size of the print area 31 are not limited, and the print layer 30 of any size can be formed at any position. Thereby, an arbitrary area can be heat-sealed according to the formation area of the printed layer 30 .

FIG. 2 is a schematic diagram illustrating the process of heat sealing a heat seal film according to one embodiment of the present invention. As shown in FIG. 2, the heat seal film 100 is typically formed with the heat seal layer 20 and the heat seal layer 20 in a state in which one end is overlapped with the adherend so that the heat seal layer 20 faces the adherend. are heat-sealed by pressing a heat-seal bar 200 against the opposite surface and heating. In the heat sealing process, the heat seal bar may be pressed against the adherend from the side opposite to the heat seal film 100, or may be pressed from both sides so as to sandwich the heat seal film 100 and the adherend. may The adherend may be the other end of the heat seal film 100, another film, or a container described later. Here, let the area|region corresponding to the part with which a heat-sealing bar is pressed be the heat-sealing process area|region A. FIG. As shown in FIG. 2, the heat seal film 100 preferably has a print area 31 and a non-print area 32 on the surface of the heat seal layer 20 opposite to the base material layer 10 in the heat seal treatment area A. have. The heat-sealing film 100 can be heat-sealed to the heat-sealing treatment area A in the same manner as the heat-sealing treatment of a conventional heat-sealing film by leaving the surface of the heat-sealing layer 20 in the area that should not be heat-sealed as a printed area 31. Only the non-printing area 32 in the heat-sealed area A can be heat-sealed when the bar is pressed.

The heat-sealed area A is typically an end area of the heat-seal film 100 and has a width corresponding to the width of the heat-seal bar 200 . The heat-sealed region A is, for example, a region with a width of 1 mm to 20 mm from the edge, preferably a region with a width of 2 mm to 10 mm from the edge. That is, the heat seal film 100 has a print area 31 and a non-print area 32 in an area having a predetermined width from the edge. The printed layer 30 can be formed at any position in the heat-sealed region A as described above. The heat seal film 100 may have two or more printed areas 31 and/or non-printed areas 32 in the heat-sealed area A. In the examples shown in FIGS. 1 and 2 , the most end side of the heat-sealed area A is the non-printing area 32 , but the most end side of the heat-sealing area A may be the printing area 31 .

The heat seal film 100 may be sheet-shaped or elongated. For example, when continuously heat-sealing the long heat-seal film 100 while transporting it using a roll-shaped heat sealer, the surface of the heat-seal layer 20 in a region that should not be heat-sealed is set as a printed region 31. As a result, there is no need to cut off the contact between the heat seal film 100 and the heat sealer even in areas where the heat seal should not be performed, and the heat seal process can be performed while the heat sealer is continuously in contact, and the heat seal process can be performed efficiently. can be

In one embodiment, the heat seal film 100 has a thermosensitive recording layer 40 that is laminated on the opposite side of the base layer 10 to the heat seal layer 20 and contains a coloring material that develops color when heated. As a result, thermal printing can be performed on the thermal recording layer 40 . The substrate layer 10 and the thermosensitive recording layer 40 are preferably transparent. As a result, the printed content on the printed layer 20 can be visually recognized from the thermosensitive recording layer 40 side. In addition, that the base material layer 10 and the thermal recording layer 40 are transparent means that they are transparent in a state before the thermal printing on the thermal recording layer 40 . The base layer 10 and the thermal recording layer 40 preferably have an opacity of 25% or less according to JIS P8138. Although not shown, the heat seal film 100 may include any appropriate functional layer instead of or in addition to the heat-sensitive recording layer 40 . Examples of the functional layer include a primer layer that improves printing characteristics when printing is performed on the surface of the thermal recording layer 40 (base material layer 10), and a primer layer in the case of performing transfer printing on the surface of the thermal recording layer 40 (base layer 10). a layer for improving transfer printing properties. Since such layers are commonly used and well known, a detailed description thereof is omitted.

FIG. 3 is a schematic plan view of a heat seal film according to one embodiment of the invention, and FIG. 4 is a schematic plan view of a heat seal film according to another embodiment of the invention. The heat seal film 100A shown in FIG. 3 has a rectangular shape, and non-printing regions 32 are formed along both ends facing each other. Such a heat-seal film 100A can be suitably used as a band seal, which will be described later. In the heat seal film 100A, the width of the non-printing area 32 is, for example, 1 mm to 100 mm, preferably 1 mm to 30 mm, more preferably 5 mm to 20 mm. The heat seal film shown in FIG. 4 has a circular or elliptical shape, and has a printed area 31 and a non-printed area 32 along the edges. Such a heat seal film can be suitably used as a top seal, which will be described later. The heat seal film 100B shown in FIG. 4(A) has a circular shape, and has a non-printing area 32 formed along the edge over almost the entire circumference, and a print area 31 formed at a part of the edge. In addition, a print area 31 is formed inside the non-print area 32 at the end. The width of the non-printing area 32 (the width in the direction from the edge toward the center) is, for example, 1 mm to 10 mm, preferably 2 mm to 5 mm. In the heat seal film 100C shown in FIG. 4B, the inner area of the heat seal film in FIG.

A-1. Substrate Layer The substrate layer is composed of any suitable material that can be used as a substrate for a heat seal film. The base material layer can be composed of, for example, resin film, metal foil, paper, non-woven fabric, woven fabric, etc., and is preferably composed of resin film.

Examples of resin films include polyolefin resins such as polyethylene and polypropylene; styrene resins such as polystyrene; polyester resins such as polyethylene terephthalate; and carbonate resins such as polycarbonate. These resins may be used singly or in combination of two or more.

The resin film may be an unstretched film or a stretched film. The stretched film may be either a uniaxially stretched film or a biaxially stretched film. Further, the substrate layer may be composed of a single layer film, or may be composed of a multilayer film.

The thickness of the base material layer is, for example, 5 μm to 150 μm, preferably 10 μm to 100 μm, more preferably 20 μm to 70 μm, from the viewpoints of handleability, ease of forming other layers, transparency, and the like. .

A-2. Heat-Seal Layer The heat-seal layer is composed of any suitable material having heat-sealability. Low-density polyethylene (LDPE), high-density polyethylene (HDPE), unoriented polypropylene (CPP), biaxially oriented polypropylene (OPP), and ethylene-vinyl acetate copolymer (EVA) are suitably used as such materials. . In addition to the above, polyolefin resins such as polyethylene and polypropylene; vinyl acetate resins such as ethylene-vinyl acetate copolymers (olefin-vinyl acetate copolymers, etc.); ethylene-(meth)acrylic acid copolymers, Examples include acrylic resins such as ionomers.

The heat seal layer may be formed by laminating (dry laminating) a film made of the resin material on the substrate layer, or may be formed by co-extrusion of the resin material together with the resin constituting the substrate layer. It may be formed on the material layer. Alternatively, it may be formed by coating a material that constitutes the heat seal layer on the base material.

The thickness of the heat seal layer, when formed by lamination or co-extrusion, is preferably 5 μm to 100 μm, more preferably 10 μm to 30 μm. When formed by coating, the thickness is preferably 0.1 μm to 10 μm, more preferably 0.5 μm to 3.0 μm.

A-3. Printed Layer The printed layer is typically formed by printing a material constituting the printed layer on the surface of the heat seal layer. Examples of the materials include coating liquids containing dyes, pigments, metals, binder component materials, solvents, and other components. Moreover, the above material may contain a metal, and the printed layer may be formed by vapor-depositing the metal on the surface of the heat seal layer. The type of metal is also not particularly limited, and for example, aluminum, aluminum alloys, copper, copper alloys (copper-nickel alloys, copper-zinc alloys, etc.), silver, silver alloys and the like can be used. The form of the metal may be any form such as metal powder, metal flakes, and metal fibers. The printed layer containing these metals is excellent in design and light-shielding properties.

Any appropriate method can be adopted as the method of printing the above material on the surface of the heat seal layer, depending on the application of the heat seal film and compatibility with the heat seal layer. For example, gravure printing, offset printing, Convex rotary printing, UV printing, silk screen printing and the like can be mentioned.

As described above, when the heat-sealing film is heat-sealed, the printed region in which the printed layer is formed on the surface of the heat-sealable layer is not heat-sealed. That is, the printed layer can have the function of sealing the heat sealability of the heat seal layer. Further, when the substrate layer and the heat-sensitive recording layer are transparent, the printed content on the printed layer can be visually recognized from the heat-sensitive recording layer side. Therefore, the printed layer not only seals the heat-sealing property of the heat-sealing layer, but also improves the design of the heat-sealing film. The printed layer can be easily patterned compared to patterning the heat seal layer. Therefore, the heat-sealable region can be easily patterned.

A-4. Thermosensitive Recording Layer As described above, the thermosensitive recording layer contains a coloring material that develops color upon heating. The coloring material is not particularly limited as long as it can be colored by heating, and a dye that can be colored by itself may be used. You may use it in combination with the color developer which can be used. Color-developing materials obtained by combining leuco dyes and color developers are also used in general thermal recording paper and the like, and are readily available and highly versatile.

Known leuco dyes can be used, for example, triphenylmethanephthalide, triallylmethane, fluorane, phenothidian, thiofluorane, xanthene, indophthalyl, spiropyran, azaphthalide, and chromenopyrazole dyes. and methine, rhodamine anilinolactam, rhodamine lactam, quinazoline, diazaxanthene, and bislactone leuco dyes. One type of leuco dye may be used alone, but by using two or more types in combination, desired color printing can be performed.

Electron acceptors such as acidic substances can be used as color developers. The color developer can be appropriately selected according to the type of leuco dye, and known ones can be used. Examples of color developers include acidic inorganic substances (bentonite, zeolite, silica gel, etc.), carboxylic acids (aliphatic monocarboxylic acids such as stearic acid; oxalic acid, polycarboxylic acids such as maleic acid; tartaric acid, citric acid, succinic acid, etc.); and aromatic carboxylic acids such as benzoic acid), as well as compounds having a phenolic hydroxyl group. These color developers can be used singly or in combination of two or more.

Furthermore, the thermosensitive recording layer may contain other materials such as a binder, if necessary. Details of materials that can be included in the thermosensitive recording layer are described in, for example, WO 2015/072411 pamphlet. The pamphlet is incorporated herein by reference in its entirety.

The heat-sensitive recording layer can be formed, for example, by dispersing the above materials in a dispersion medium to prepare a coating solution, coating the surface of the substrate layer, and drying the coating film. When dispersing the constituent material of the thermosensitive recording layer in the dispersion medium, a known mixer, sand mill, bead mill, or other known pulverizer may be used. As the dispersion medium, for example, organic solvents such as alcohols, ketones, and nitriles may be used, and water is preferably used.

The thermosensitive recording layer may be formed on the entire surface of the base material layer, or may be formed only on a limited area of the heat seal film when the area to be printed is limited.

B. Use of heat-sealable film The heat-sealable film described in section A above can be used in the production of packaging materials. Examples of the packaging material include a packaging bag manufactured by heat-sealing the ends of a heat-seal film to form a bag-like shape. Types of packaging bags include, for example, folding bags, gusset bags, and three-sided bags. In addition to the packaging bags described above, examples of the packaging material include a packaging material using a heat-seal film as a band seal, a cup-shaped packaging material using a heat-seal film as a top seal, and the like.

FIG. 5 is a schematic diagram of a packaging material according to one embodiment of the present invention, (A) is a perspective view of the packaging material, and (B) is a cross-sectional view taken along line BB of (A). The packaging material 200 has a container 110 and a heat-seal film 100 as a band seal for the container 110 . The heat-seal film 100 is wrapped around the outer peripheral surface of the container 110 and heat-sealed at both ends to form a heat-sealed portion 101 . As the heat-seal film used for banding in this way, the heat-seal film 100A shown in FIG. 3 can be suitably used. Examples of the container include commercially available polystyrene containers for lunch boxes. When a boxed lunch having a conventional heat-seal film as a wrapping is heated in a microwave oven or the like, the wrapping may be welded to the container. On the other hand, as shown in FIG. 3, by using a heat-sealing film having a printing region other than the end portion as band sealing, it is possible to prevent welding to the container during heating.

Figure 6 is a schematic perspective view of a packaging material according to another embodiment of the invention. The packaging material 201 has a container 120 and a heat seal film 100 as a top seal for the container 120 . The heat-seal film 100 is heat-sealed to the edge of the opening of the container 120 so as to close the opening of the container 120 . As the heat-sealing film used for banding in this way, the heat-sealing film 100B (100C) shown in FIG. 4 can be preferably used. The container 120 may be, for example, a cup-shaped container having a circular opening. As a top seal for such a packaging material, as shown in FIG. 4, by using a heat-seal film having a printed area and a non-printed area along the edges, heat can be applied in the same manner as in conventional heat-sealing. Only the non-printing area can be heat-sealed without heat-sealing the printing area when the seal bar is pressed. This makes it possible to impart air permeability without completely sealing the cup-shaped container, for example, to allow air or steam to pass through.

C. Method for manufacturing packaging material A method for manufacturing a packaging material includes heating a region including a printed region and a non-printed region at the end of the heat seal film to heat seal the heat seal layer in the printed region without heat sealing. Heat sealing the heat seal layer in the printed area. The packaging material may be a packaging bag made of one heat-sealed film, a packaging bag made of two or more heat-sealed films, or a packaging material using a heat-sealed film as a wrapping. or a packaging material using a heat seal film as a top seal. When manufacturing a packaging bag made of a single heat-seal film, for example, one end and the other end are overlapped, and a heat-seal bar is pressed against the surface opposite to the heat-seal layer. Heating heat seals the heat seal layer in the non-printing areas. When manufacturing a packaging bag made of two or more heat-sealed films, for example, while the end of the heat-sealed film and the end of another heat-sealed film are overlapped, the surface opposite to the heat-sealed layer The heat-sealing layer in the non-printing area is heat-sealed by pressing the heat-sealing bar and heating. When manufacturing a packaging material using a heat seal film as a top seal, for example, a heat seal film having a printed region and a non-printed region at a position corresponding to the edge of the opening of the container is covered with the heat seal film, and the opening is The heat-seal layer is heat-sealed in the non-printing areas by pressing a heat-sealing bar against the heat-sealing film over the entire edge of the print and applying heat.

The heat seal film of the present invention is suitably used as a packaging film.

REFERENCE SIGNS LIST 10 substrate layer 20 heat seal layer 30 print layer 31 print area 32 non-print area 40 thermosensitive recording layer 100 heat seal film 200 packaging material

Claims (8)

Having a base layer and a heat seal layer laminated on one side of the base layer,
On the surface of the heat seal layer opposite to the base layer, a printed region having a printed layer formed thereon and a non-printed region having no printed layer formed thereon,
It has a rectangular shape, and the non-printing regions are formed along both ends facing each other ,
A heat seal film, wherein the non-printed areas extend across the edges of the heat seal layer, the printed areas being located between the non-printed areas formed along opposite ends . Having a base layer and a heat seal layer laminated on one side of the base layer,
On the surface of the heat seal layer opposite to the base layer, a printed region having a printed layer formed thereon and a non-printed region having no printed layer formed thereon,
It has a circular or elliptical shape, and the printed area and the non-printed area are formed along the edge ,
The heat seal film , wherein the printed area is formed on a part of the edge of the heat seal layer, and the non-printed area extends over the entire circumference of the edge of the heat seal layer excluding the printed area . 3. The heat-sealing film according to claim 1, wherein the heat-sealing treated area has the printed area and the non-printed area. 4. The heat seal film according to any one of claims 1 to 3, further comprising a thermosensitive recording layer laminated on the opposite side of the base layer to the heat seal layer and containing a coloring material that develops color when heated. 5. The heat seal film according to claim 4, wherein the base layer and the thermosensitive recording layer are transparent. A packaging material comprising a container and the heat seal film according to claim 1 as a banding of the container. A packaging material comprising a container and the heat seal film according to claim 2 as a top seal of the container. A method for manufacturing a packaging material using the heat seal film according to any one of claims 1 to 5,
By heating a region including the printed region and the non-printed region at the end of the heat seal film, the heat seal is performed in the non-printed region without heat-sealing the heat seal layer in the printed region. A method of manufacturing a packaging material comprising heat sealing layers.

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