JP7427956B2 - Method for manufacturing paper packaging materials and paper packaging bags - Google Patents

Description

The present invention relates to a paper packaging material having a heat-adhesive resin layer and a method for manufacturing the same. The present invention also relates to a paper packaging bag sealed by thermal bonding.

A conventional paper packaging bag is disclosed in Patent Document 1. This paper packaging bag is formed from a paper packaging material having a heat-adhesive resin layer provided on one side of a paper base. A printing layer for printing a pattern is provided on the other side of the paper base material. The thermoadhesive resin layer is formed by dry laminating a resin film on one side of a paper base material. A paper packaging bag is formed by arranging the thermoadhesive resin layer on the inner surface and thermally bonding the opposing thermoadhesive resin layers.

JP2019-38546A (pages 4 to 8, Figure 6)

However, the conventional paper packaging bags described above have a problem of poor recyclability because the heat-adhesive resin layer is formed of a resin film. Furthermore, since the surface of the paper base material has low smoothness, there is a problem in that the printing reproducibility of designs such as gradations formed by the printing layer on the paper base material is poor. This has made it difficult to obtain paper packaging bags with high aesthetic appeal.

An object of the present invention is to provide a paper packaging material that can improve recyclability and pattern printing reproducibility, a paper packaging bag using the same, and a method for manufacturing the paper packaging material.

In order to achieve the above object, the method for producing a paper packaging material of the present invention includes a step of applying a release agent on a base film to form a surface protection layer consisting of a cured film of the release agent, and a step of forming a surface protection layer consisting of a cured film of the release agent. A step of printing a pattern layer to form a pattern with ink on the layer to form a transfer film, a step of printing a thermoadhesive resin on one side of the paper base material, and a step of printing the other side of the paper base material and the transfer film. The method is characterized by comprising the steps of adhering the pattern layer to the pattern layer using an adhesive, and peeling off the base film.

Further, the present invention is characterized in that the method for manufacturing a paper packaging material having the above structure is characterized in that the adhesive layer enters between the pattern layers and is bonded to the surface protection layer.

Further, the present invention is characterized in that the method for manufacturing a paper packaging material having the above structure is characterized in that the surface protective layer is formed of an acrylic release agent.

Further, the present invention is characterized in that the method for producing a paper packaging material having the above-mentioned structure is characterized in that the heat-adhesive resin layer is formed of a water-based resin film.

Furthermore, the paper packaging material of the present invention includes a thermoadhesive resin layer printed with a thermoadhesive resin on one side of a paper base, an adhesive layer made of an adhesive arranged on the other side of the paper base, and an ink-based adhesive layer. The device is characterized by comprising: a pattern layer formed with a pattern formed thereon and disposed on the adhesive layer; and a surface protection layer made of a cured film of a release agent disposed on the pattern layer.

Further, the present invention is characterized in that the paper packaging material having the above structure is characterized in that the adhesive layer enters between the pattern layers and is bonded to the surface protection layer.

Further, the paper packaging bag of the present invention is characterized in that it is formed into a bag shape by thermally adhering the opposing thermoadhesive resin layers of the paper packaging material having the above structure.

According to the method for producing a paper packaging material of the present invention, the base film is peeled off after the paper base material is bonded to the transfer film, which has a surface protection layer and a pattern layer made of a cured film of a release agent on the base film. be done. Thereby, the pattern layer formed on the highly smooth base film is transferred to the paper base material, so that the printing reproducibility of the pattern layer can be improved. Furthermore, since the heat-adhesive resin layer is formed by printing and no extruded resin is provided below the pattern layer, the amount of resin used in the paper packaging material can be reduced. Thereby, the recyclability of the paper packaging material and the paper packaging bag can be improved. At this time, a decrease in air permeability and resistance of the paper packaging material can be suppressed by the adhesive layer and the surface protection layer.

Further, according to the paper packaging material and paper packaging bag of the present invention, a thermoadhesive resin layer is printed on one side of a paper base material, and a pattern layer and a cured film of a release agent are formed on the other side via an adhesive layer. A surface protective layer is arranged. Therefore, the pattern layer can be formed on a highly smooth base film and transferred to the paper base material, and the printing reproducibility of the pattern layer can be improved. Furthermore, it is possible to suppress a decrease in air permeability resistance, reduce the amount of resin used in paper packaging materials, and improve the recyclability of paper packaging materials and paper packaging bags.

A schematic sectional view showing the layer structure of a paper packaging material according to an embodiment of the present invention A schematic cross-sectional view showing the manufacturing process of a paper packaging material according to an embodiment of the present invention A front view showing a paper packaging bag formed from a paper packaging material according to an embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the layer structure of a paper packaging material 20 according to one embodiment. A paper packaging bag 1 (see FIG. 3) is made using the paper packaging material 20. In the paper packaging material 20, a thermoadhesive resin layer 29 is arranged on one side of a paper base material 28, and a pattern layer 23 and a surface protection layer 22 are arranged on the other side with an adhesive layer 24 interposed therebetween.

The paper base material 28 is not particularly limited, but includes high-quality paper, thin imitation paper, bleached kraft paper, unbleached kraft paper, single-gloss kraft paper, heavy-duty kraft paper, pure white roll paper, glassine paper, white paperboard, paper tube base paper, Liner base paper, clay coat paper, recycled paper, etc. can be used. The paper base material 28 may be made of single-layer paper or multi-layer paper.

The paper base material 28 preferably has a basis weight of 25 to 125 g/m ² . If the basis weight of the paper base material 28 is smaller than 25 g/m ² , the paper packaging material 20 will be easily torn, and if it is larger than 125 g/m ² , it will be difficult to form it into a bag shape.

The thermoadhesive resin layer 29 is made of a printed coating film of a thermoadhesive resin, and is formed by printing a water-based thermoadhesive resin onto the paper base material 28 . Thereby, the thermal adhesive resin layer 29 is formed of a water-based resin film.

The water-based resin film is a resin film obtained by drying a liquid in which a resin is dissolved or dispersed in an aqueous medium or a hydrophilic medium. Specifically, resin films with residual surfactants for dissolving or dispersing the resin in the medium, and resins that contain highly hydrophilic carboxylic acids, sulfonic acids, etc. in the resin skeleton and can be dissolved or dispersed in the medium. Examples include a resin film formed by a resin film formed with a resin film, a resin film in which these resins coexist, and the like.

The thermal adhesive resin printing liquid may be of a water-soluble type or a water-dispersion type (colloidal dispersion type, emulsion type). The paper packaging bag 1 (see FIG. 3) is formed by overlapping the opposing thermoadhesive resin layers 29 and thermally adhering them under pressure and heat.

Specific examples of water-based thermoadhesive resins include water-based acrylic emulsions and water-based polyolefins (polyethylene, EMA, EMAA, EVA, ionomer, etc.).

Since the heat-adhesive resin layer 29 is made of a printed coating film, the amount of resin used in the paper packaging material 20 can be reduced and recyclability can be improved. Moreover, since the thermal adhesive resin layer 29 is formed of a water-based resin film, the disintegration properties of the paper packaging material 20 during recycling are improved. Thereby, the recyclability of the paper packaging material 20 can be further improved.

Furthermore, the water-based resin film does not contain so-called oily organic solvents (toluene, MEK, ethyl acetate, etc.) when it is formed. Thereby, it is possible to prevent odor caused by residual solvent in the thermally adhesive resin layer 29 disposed on the inner surface of the paper packaging bag 1 (see FIG. 3). Therefore, the paper packaging material 20 can be used as a food paper packaging material suitable for food packaging. Note that in applications where residual solvent is allowed, the thermal adhesive resin layer 29 may be formed of a non-aqueous resin, although the disintegration property will be reduced.

The surface protection layer 22 and the pattern layer 23 are provided on a base film 21 (see FIG. 2), which will be described later, and are adhered to a paper base material 28 by an adhesive layer 24. The adhesive layer 24 is formed of an adhesive such as an acrylic adhesive or a urethane adhesive.

The surface protection layer 22 is formed of a cured film of a transparent release agent. As the release agent for forming the surface protective layer 22, a silicone release agent, a fluorine release agent, an acrylic release agent, an alkyd release agent, a long chain alkyl group release agent, or the like can be used. Acrylic resins used in acrylic release agents are more desirable because they can be designed to have a wide range of degrees of polymerization and can be designed and used depending on the base material and release properties.

The pattern layer 23 is made of a printed coating film in which ink is printed on the surface protection layer 22, and forms a desired pattern (including characters). The plurality of inks forming the pattern layer 23 are mainly composed of urethane resin, nitrified cotton resin, etc., and contain colored pigments such as cyan, magenta, yellow, and black, and white pigments, respectively.

FIGS. 2(a) to 2(d) are schematic cross-sectional views showing the manufacturing process of the paper packaging material 20. The paper packaging material 20 is manufactured through a release agent coating process, a pattern printing process, a heat-adhesive resin layer forming process, an adhesion process, and a peeling process.

In the release agent coating process, as shown in FIG. 2A, a release agent is applied onto a base film 21 of resin such as polyethylene terephthalate, and cured by drying, heating, ultraviolet irradiation, or the like. The coating amount of the release agent is, for example, 1 to 3 g/m ² . As a result, a surface protection layer 22 made of a cured film of the release agent is formed.

In the pattern printing step, as shown in FIG. 2(b), a pattern layer 23 forming a pattern is printed on the surface protection layer 22. As a result, a transfer film 25 having a surface protection layer 22 and a pattern layer 23 provided on the base film 21 is formed. The pattern layer 23 is provided dispersedly at desired positions on the base film 21, but may be provided over the entire surface.

As shown in FIG. 2(c), the heat-adhesive resin layer forming step is carried out by printing an aqueous heat-adhesive resin having a solid content of, for example, 1 to 20 g/m ² on one side of the paper base material 28 to form the heat-adhesive resin. Form layer 29. If the amount of the thermoadhesive resin is less than 1 g/m ² , the sealing strength of the thermally adhesive portion of the paper packaging bag 1 (see FIG. 3), which will be described later, cannot be obtained. If the amount of resin in the heat-adhesive resin layer 29 is more than 20 g/m ² , the amount of resin used will increase and the printing characteristics will deteriorate.

In the adhesion process, as shown in FIG. 2(d), an adhesive is applied to the other surface of the paper base material 28 (the surface opposite to the thermally adhesive resin layer 29) at a rate of, for example, 2 to 5 g/m ² and a transfer film is applied. 25 to form an adhesive layer 24. When the pattern layers 23 are provided in a dispersed manner, the adhesive layer 24 enters between the pattern layers 23 and is bonded to the surface protection layer 22.

In the peeling process, the base film 21 is peeled off after the adhesion process. Thereby, the pattern layer 23 and the surface protection layer 22 are transferred onto the paper base material 28, and a paper packaging material 20 (see FIG. 1) is obtained.

The pattern layer 23 is printed on the highly smooth base film 21 via the surface protection layer 22. Therefore, the printing reproducibility of patterns such as gradation formed by the pattern layer 23 can be improved.

Note that even if a base layer such as extruded resin or resin film is provided on the paper base material 28 and the pattern layer 23 is printed on the base layer, the printed surface of the pattern layer 23 can be formed to be highly smooth. However, the amount of resin used increases depending on the base layer, and the disintegration properties of the paper packaging material 20 during recycling deteriorate. Therefore, by printing the pattern layer 23 on the base film 21 that is removed in the peeling process and transferring it to the paper base material 28, the amount of resin used in the paper packaging material 20 can be reduced and the disintegration properties can be improved. . Thereby, the recyclability of the paper packaging material 20 and the paper packaging bag 1 (see FIG. 3) formed by the paper packaging material 20 can be improved.

FIG. 3 shows a front view of the paper packaging bag 1 formed from the paper packaging material 20. The paper packaging bag 1 is formed into a pillow shape having a back seal part 2 and an edge seal part 3. A storage section 9 for storing contents 10 is provided inside the paper packaging bag 1. The contents 10 consist of individually packaged (primary packaging) foods (confectionery, etc.), medicines, etc., and the paper packaging bag 1 provides secondary packaging for the contents 10.

The back seal part 2 is formed by thermally adhering the opposite ends of the body part 5 in which the paper packaging material 20 is arranged in a cylindrical shape with opposing heat-adhesive resin layers 29 (see FIG. 1). The edge seal portions 3 and 4 are formed by thermally bonding opposing heat-adhesive resin layers 29 to both ends of the body portion 5 in the axial direction. Both ends of the body 5 in the axial direction are formed, for example, in a sawtooth shape for opening.

The contents 10 are enclosed in the paper packaging bag 1 by filling the storage portion 9 with the contents 10 and thermally adhering the opposing thermoadhesive resin layers 29.

The paper packaging material 20 has an adhesive layer 24 and a surface protection layer 22 arranged on a paper base material 28 . Therefore, the decrease in air permeability resistance of the paper packaging material 20 due to the formation of the thermal adhesive resin layer 29 by printing is suppressed. As defined in JIS P8117:2009, the air permeation resistance is the time it takes for 100 mL of air to permeate per unit area and unit pressure difference. Therefore, the outflow of the air filling the inside of the paper packaging bag 1 is suppressed, and the contents 10 can be protected when the paper packaging bag 1 containing the contents 10 is transported or stored.

As an example, the air permeation resistance of the paper wrapping paper 20 was measured and was found to be 15,000 seconds. The paper base material 28 of this paper wrapping paper 20 was a single gloss kraft paper (basis weight 64 g/m ² ). The heat-adhesive resin layer 29 was printed to a thickness of about 3 to 4 μm using a printing liquid of an aqueous polyolefin dispersion having a solid content of 4 g/m ² . The surface protective layer 22 was formed by applying 3 g/m ² of acrylic nitrified cotton, and the adhesive layer 24 was formed by applying 3 g/m ² of acrylic adhesive onto the paper base material 28.

For comparison, the air permeability resistance of a paper wrapping paper which was formed in the same manner as above except that the pattern layer 23 was printed on the paper base material 28 and the adhesive layer 24 and the surface protection layer 22 were omitted was 50 seconds. Ta.

Although the paper packaging bag 1 is formed into a pillow shape, it may be formed into other forms such as a free-standing bag, a sealed four-sided seal bag, or a three-sided sealed bag before being sealed. Further, although the paper packaging bag 1 is used for secondary packaging, it may also be used for primary packaging.

According to this embodiment, the base film 21 is peeled off after the paper base material 28 is bonded to the transfer film 25, which has the surface protection layer 22 and the pattern layer 23 made of a cured film of a release agent on the base film 21. Ru. Thereby, the pattern layer 23 formed on the highly smooth base film 21 is transferred to the paper base material 28, so that the printing reproducibility of the pattern layer 23 can be improved.

Further, a thermoadhesive resin layer 29 is printed on one side of the paper base material 28, and an adhesive layer 24, a pattern layer 23, and a surface protection layer 22 consisting of a cured film of a release agent are arranged in this order on the other side. Therefore, by forming the pattern layer 23 on the highly smooth base film 21 and transferring it to the paper base material 28 using the adhesive layer 24, the printing reproducibility of the pattern layer 23 can be improved.

Further, since the heat-adhesive resin layer 29 is formed by printing and no extruded resin or the like is provided below the pattern layer 23, the amount of resin used in the paper packaging material 20 can be reduced. Thereby, the recyclability of the paper packaging material 20 and the paper packaging bag 1 can be improved. At this time, the adhesive layer 24 and the surface protection layer 22 can suppress a decrease in the air permeability resistance of the paper packaging material 20. Therefore, the contents 10 can be protected when the paper packaging material 20 enclosing the contents 10 is transported or stored.

Moreover, since the adhesive layer 24 enters between the pattern layers 23 and is bonded to the surface protection layer 22, peeling of the surface protection layer 22 can be prevented.

Moreover, since the surface protection layer 22 is formed of an acrylic release agent, it can be designed and used depending on the base film 21 and release properties, and the paper packaging material 20 can be easily formed.

Moreover, since the thermally adhesive resin layer 29 is formed of a water-based resin film, the disintegration properties of the paper packaging material 20 are improved, and the recyclability can be further improved. Further, the paper packaging bag 1 for food can be easily formed while preventing odor caused by residual solvent.

According to the present invention, it can be used for packaging bags for foods, etc.

1 Paper packaging bag 2 Back seal portion 3, 4 Edge seal portion 5 Body portion 9 Storage portion 10 Contents 20 Paper packaging material 21 Base film 22 Surface protection layer 23 Pattern layer 24 Adhesive layer 25 Transfer film 28 Paper base Material 28a Coating layer 29 Heat-adhesive resin layer

Claims (4)

a step of applying a release agent on the base film to form a surface protective layer consisting of a cured film of the release agent;
forming a transfer film by printing a pattern layer that forms a pattern using ink on the surface protective layer;
A step of printing a heat-adhesive resin made of a water-based acrylic emulsion or a water-based polyolefin at 1 to 20 g/m ² on one side of the paper base material to form a heat-adhesive resin layer;
bonding the other surface of the paper base material and the pattern layer of the transfer film with an adhesive;
a step of peeling off the base film;
A method for producing a paper packaging material, comprising: forming a paper packaging material in which the surface protection layer and the thermoadhesive resin layer are disposed on the outer surface . 2. The method of manufacturing a paper packaging material according to claim 1, wherein the adhesive enters between the pattern layers and adheres to the surface protection layer. 3. The method for producing a paper packaging material according to claim 1, wherein the surface protective layer is formed of an acrylic release agent. It is characterized in that it is formed into a bag shape by thermally adhering the opposing thermoadhesive resin layers of a paper packaging material manufactured by the method for manufacturing a paper packaging material according to any one of claims 1 to 3. A method for manufacturing a paper packaging bag.

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