JP2020111345A - Packaging material and paper container - Google Patents

Abstract

To provide a packaging material for paper container using a paper base material which prevents remaining of an organic solvent and causes no foaming phenomenon in an inner surface film in heating, and a paper container manufactured using the same.SOLUTION: When an anchor coat layer 13 is formed on one surface of a paper base material 12, and an inner surface side film 15 is layered on the anchor coat layer through a molten extrusion resin 14 to manufacture a packaging material 10, the anchor coat layer is formed of an aqueous polyethylene dispersion resin.SELECTED DRAWING: Figure 1

Description

The present invention relates to a liquid paper container manufactured by using a paper base material and a packaging material that constitutes the paper container.

Liquid paper containers manufactured using paper substrates are well known. As such a liquid paper container, for example, a paper cup, a gobel top liquid paper container, a flat top liquid paper container, a cylindrical liquid paper container, and the like are known.

In each type of liquid paper container, a packaging material is used in which a liquid blocking film is laminated on the inner surface of the paper base material, and the body is rounded and heat sealed at both ends. Are formed. Further, in the Gobel top type liquid paper container, the flat top type liquid paper container or the cylindrical liquid paper container, hot air is blown to the top and bottom to melt the resin layer on the inner surface side, and the resin layer thus melted is pressure-bonded. It is hermetically sealed.

When the packaging material in which the inner surface film is laminated on the paper base material is heated in this way, water or air contained in the paper base material expands, and as a result, the inner surface film surface may foam. Such a foaming phenomenon makes the quality of the paper container unstable and may cause leakage of the contents and deterioration of the barrier property.

Therefore, in order to prevent such a foaming phenomenon, in the invention of Patent Document 1, a two-component curing type urethane anchor coating agent is applied to a paper base material, and the anchor coating layer surface and the inner surface film are melted through an extruded resin. Are stacked.

Japanese Patent No. 4757001

However, a general two-component curing type urethane anchor coating agent is dissolved in an organic solvent and applied, and there is a possibility that a part of the solvent may remain.

Therefore, the present invention is a packaging material for a paper container using a paper base material, in which there is no possibility that an organic solvent remains, and furthermore, the foaming phenomenon does not occur in the inner film during heating, and the packaging material is used. It is intended to provide a paper container manufactured by

That is, the invention according to claim 1 is a packaging material having an anchor coat layer on one surface of a paper base material, and laminating a film on the anchor coat layer via a melt-extruded resin,
The packaging material is characterized in that the anchor coat layer is composed of a water-based polyethylene dispersion resin.

Next, the invention according to claim 2 is the packaging material according to claim 1, wherein the coating amount of the anchor coat layer is 0.5 g/m ² or more.

Next, the invention according to claim 3 is the packaging material according to claim 1 or 2, wherein the melt-extruded resin is composed of a polyethylene resin.

Next, the invention according to claim 4 is the packaging material according to any one of claims 1 to 3, wherein the film has a gas barrier property.

Next, an invention according to claim 5 is a paper container using the packaging material according to any one of claims 1 to 4 and having the film as an inner surface side.

In the present invention, since the aqueous dispersion resin containing no organic solvent is used as the anchor coating agent, there is no possibility that the organic solvent remains. Moreover, as can be seen from the examples described below, when an aqueous polyethylene dispersion resin is used as the aqueous dispersion resin, the inner surface film does not foam when heated.

FIG. 1 is a cross-sectional explanatory view of a specific example of the packaging material of the present invention. FIG. 2 is a perspective view of a first concrete example of the paper container of the present invention. FIG. 3 is a perspective view of a second specific example of the paper container of the present invention. FIG. 4 is a perspective view of a third concrete example of the paper container of the present invention.

Hereinafter, specific examples of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional explanatory view of a specific example of the packaging material of the present invention.

The packaging material 10 uses paper as a base material 12. The outer surface side resin layer 11 is laminated on one surface thereof. An anchor coat layer 13 is applied and formed on the opposite surface.

Then, the paper base material 12 and the inner surface side film 15 are laminated with the melt extruded resin 14 interposed therebetween.

The paper base material 12 may be selected according to the paper container to be manufactured. For example, a paper base material having a basis weight of 250 to 400 g/m ² .

Further, as the anchor coat layer 13, it is necessary to use a water-based polyethylene dispersion resin. Since the anchor coat layer 13 is water-based and does not contain an organic solvent, there is no possibility that the organic solvent remains in the anchor coat layer 13. Further, when the water-based polyethylene dispersion resin is applied to the paper base material to form the anchor coat layer 13, the water-based polyethylene dispersion resin fills the voids between the fibers of the paper base material 12 and the flow of water to the inside of the paper container. In addition, anchoring of the melt-extruded resin 14 onto the paper base material 12 is strengthened, and foaming during heating is suppressed. Therefore, peeling between the paper base material and the inner film 15 can be prevented.

The anchor coat layer 13 can be formed by applying and drying the paper base material 12 using an arbitrary application method. For example, a gravure coating method, a roll coating method, or the like. The coating amount of the anchor coat layer 13 is preferably 0.5 g/m ² or more. If the coating amount is less than this, the function cannot be sufficiently exerted, and the foaming phenomenon may occur during heating.

The inner surface side film 15 is a film forming the inner surface. It may have either a single-layer structure or a multi-layer structure, but it is desirable that the innermost surface thereof has a heat-sealing property. Further, it is desirable to have a gas barrier property depending on the contents to be contained.

As the gas barrier inner film 15, a film having a multi-layer structure including a gas barrier layer in a part of its layer structure can be used. For example, it is a film having a multilayer structure in which a resin film, a gas barrier layer, and a heat-sealing resin layer are laminated in this order.

As the gas barrier layer, for example, a metal foil, a metal vapor deposition film having a metal vapor deposition layer, or an inorganic vapor deposition film having a gas barrier inorganic vapor deposition layer can be used. Although these are all well known, an aluminum foil can be exemplified as the metal foil. As a typical example of the metal vapor deposition film, a film obtained by vapor deposition of aluminum using a polyester film or a polyamide film as a vapor deposition base material can be exemplified. As the inorganic vapor deposition film, a film obtained by vapor deposition of silicon oxide or aluminum oxide using a polyester film or a polyamide film as a vapor deposition substrate can be exemplified.

Heat sealable resins are also well known. Examples thereof include polyolefin resins such as low density polyethylene resin, medium density polyethylene resin, linear low density polyethylene resin and polypropylene resin.

Next, the melt-extruded resin 14 bonds the paper base material 12 and the inner surface side film 15 by heating and melting this resin and extruding it between the paper base material 12 and the inner surface side film 15 and pressing it. It is a thing. The paper base material 12 needs to be arranged so that the anchor coat layer 13 contacts the molten extruded resin 14. Further, it is desirable that the inner film 15 is arranged so that the heat-sealable resin is located on the opposite side of the melt extruded resin 14.

As the melt-extruded resin 14, any resin can be used as long as it can firmly adhere to both the anchor coat layer 13 and the inner surface side film 15. Since the anchor coat layer 13 is made of polyethylene resin, the melt-extruded resin 14 is also preferably polyethylene resin. The surface of the inner film 15 that contacts the melt-extruded resin 14 is also preferably made of polyethylene resin.

The outer surface side resin layer 11 constitutes the outer surface of the paper container to prevent the paper container from being contaminated or damaged. Further, since the outer surface side resin layer 11 and the inner surface side film 15 may be sealed to each other during the production of the paper container, in this case, the outer surface side resin layer 11 may also be made of a heat sealable resin. desirable. For example, the above-mentioned polyolefin resin.

The packaging material 10 can be manufactured, for example, by providing an anchor coat layer 13 on a paper base material 12, laminating an inner surface side film 15 via a melt extruded resin 14, and then forming an outer surface side resin layer 11. it can. Alternatively, the outer surface side resin layer 11 may be formed on the paper base material 12, the anchor coat layer 13 may be provided, and the inner surface side film 15 may be laminated via the melt extruded resin 14.

The packaging material 10 can be used as a material for a paper container such as a paper cup, a Gobel-top type liquid paper container, a flat-top liquid paper container, and a cylindrical liquid paper container. 2 is a perspective view showing an example of a cylindrical liquid paper container A, FIG. 3 is a perspective view showing an example of a gobel top liquid paper container B, and FIG. 4 is a perspective view showing an example of a paper cup C, both of which are shown. It can be produced by a known method.

(Example 1)
As a paper base material, NCAN-G320 (cup base paper, basis weight 320 g/m ² ) manufactured by Nippon Paper Industries Co., Ltd. was used.

Further, as the inner surface film, a film having a multilayer structure in which a polyethylene resin layer, a polyester film, an inorganic vapor deposition film, and a polyethylene resin layer were laminated in this order from the outer surface side of the paper container was used. The inorganic vapor deposition film is a film obtained by vapor deposition of aluminum oxide using a polyester film as a vapor deposition base material.

Then, first, a polyethylene resin was laminated on one surface of the paper base material to form an outer surface side resin layer.

In addition, an aqueous polyethylene dispersion resin was applied to the opposite side and dried to form an anchor coat layer. The coating amount is 0.5 g/m ² .

Next, the polyethylene resin was put into a melt extrusion molding machine, the resin was melted, extruded between the paper base material and the inner surface side film, and pressure-bonded to integrally bond and laminate the whole. The orientation of the paper substrate was such that the anchor coat layer was in contact with the melt extruded polyethylene resin. The orientation of the inner surface side film is such that the polyethylene resin layer, the polyester film, the inorganic vapor deposition film, and the polyethylene resin layer are in order from the melt extruded polyethylene resin.

The packaging material thus obtained was used to manufacture the cylindrical liquid paper container shown in FIG. That is, first, the packaging material was rolled, and both ends thereof were overlapped and heat-sealed to form a cylindrical body portion. Next, a separately prepared lid member and bottom member were applied to the top and bottom, respectively, and these were heated and joined to the tubular body.

(Example 2)
A packaging material was produced in the same manner as in Example 1 except that the coating amount of the water-based polyethylene dispersion resin was 4.0 g/m ² , and a cylindrical liquid paper container was produced.

(Example 3)
A packaging material was produced in the same manner as in Example 1 except that the coating amount of the aqueous polyethylene dispersion resin was 6.0 g/m ² , and a cylindrical liquid paper container was produced.

(Comparative Example 1)
A packaging material was produced in the same manner as in Example 1 except that the paper base material and the inner surface side film were adhesively laminated through a melt extruded polyethylene resin without forming an anchor coat layer, and a cylindrical liquid paper container. Was manufactured.

(Comparative example 2)
A packaging material was produced in the same manner as in Example 1 except that a two-component curing type urethane anchor coating agent was used instead of the water-based polyethylene dispersion resin, and a cylindrical liquid paper container was produced. The coating amount of the two-component curing type urethane anchor coating agent is 0.5 g/m ² .

(Comparative example 3)
A packaging material was produced in the same manner as in Comparative Example 2 except that the application amount of the two-component curing type urethane anchor coating agent was 4.0 g/m ² , and a cylindrical liquid paper container was produced.

(Comparative Example 4)
A packaging material was produced in the same manner as in Comparative Example 2 except that the application amount of the two-component curing type urethane anchor coating agent was 6.0 g/m ² , and a cylindrical liquid paper container was produced.

(Comparative example 5)
A packaging material was produced in the same manner as in Example 1 except that a polyethyleneimine-based anchor coating agent was used instead of the water-based polyethylene dispersion resin, and a cylindrical liquid paper container was produced. The amount of the polyethyleneimine-based anchor coating agent applied was 0.5 g/m ² .

(Comparative example 6)
A packaging material was produced in the same manner as in Comparative Example 2 except that the coating amount of the polyethyleneimine-based anchor coating agent was 4.0 g/m ² , and a cylindrical liquid paper container was produced.

(Evaluation)
The cylindrical liquid paper containers of Examples 1 to 3 and Comparative Examples 1 to 6 were evaluated from three viewpoints.

That is, first, the presence or absence of residual organic solvent. The detection of the residual solvent was carried out by sealing a test piece cut into a size of 10 cm×10 cm from each packaging material immediately after the paper base material and the inner surface side film were pressure-bonded into a glass bottle, and at 80° C. for 20 minutes. After storage, the organic solvent contained in the gas in the glass bottle was analyzed by gas chromatography. The organic solvent in the gas in the glass bottle is five kinds of ethyl acetate, methyl ethyl ketone, isopropyl alcohol, normal propyl acetate, and toluene.

Then, the case the total amount of organic solvent is less than 3.0 mg / ^{m 2} "○", the case of 3.0~5.0mg / ^{m 2} "△", 5.0 mg / ^{m 2} or more when the "X" was evaluated.

Next, the presence or absence of the foaming phenomenon was evaluated. This evaluation was performed by visually observing each paper container. The case where no foaming phenomenon was observed was evaluated as “◯”, and the case where the foaming phenomenon was observed was evaluated as “x”.

Finally, each of these paper containers was filled with turpentine oil and allowed to stand for 30 minutes or more to observe whether or not leakage occurred. With respect to the presence or absence of the leakage, 1000 tests were conducted for each paper container, and the number of paper containers in which the leakage occurred was counted.

The results are shown in Table 1. In addition, in the table, "aqueous PE dispersion" means "aqueous polyethylene dispersion resin".

(Discussion)
As can be seen from this result, when the anchor coat layer is not provided (Comparative Example 1), the foaming phenomenon cannot be prevented, and peeling (delamination) occurs, and leakage of the contents easily occurs. When the anchor coat layer is formed by using the polyethyleneimine-based anchor coat agent (Comparative Examples 5 to 6), the foaming phenomenon occurs and the leakage of the content is reduced, but this cannot be sufficiently prevented.

On the other hand, when the anchor coat layer is formed by using the two-component curing type urethane anchor coating agent (Comparative Examples 2 to 4), the foaming phenomenon can be prevented and the content does not leak. However, in this case, since the organic solvent remains, it is not possible to eliminate the possibility that the residual solvent is mixed in the contents.

On the other hand, when the anchor coat layer is formed by using the water-based polyethylene dispersion resin (Examples 1 to 3), the foaming phenomenon can be prevented, the contents do not leak, and There is no risk of organic solvent remaining. Moreover, a coating amount of only 0.5 g/m ² is sufficient.

10: packaging material 11: outer surface resin layer 12: paper base material 13: anchor coat layer
14: Melt extruded resin 15: Inner surface side film A: Cylindrical liquid paper container B: Goebeltop liquid paper container C: Paper cup

Claims (5)

A packaging material having an anchor coat layer on one surface of a paper base material and laminating a film on the anchor coat layer via a melt-extruded resin,
A packaging material, wherein the anchor coat layer is composed of an aqueous polyethylene dispersion resin. The packaging material according to claim 1, wherein the coating amount of the anchor coat layer is 0.5 g/m ² or more. The packaging material according to claim 1 or 2, wherein the melt-extruded resin is composed of a polyethylene resin. The packaging material according to claim 1, wherein the film has a gas barrier property. A paper container using the packaging material according to any one of claims 1 to 4 and having the film on the inner surface side.

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