JP2004168421A - Packaging container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging container on which a decorative print, etc. is beautifully put into, does not generate an odor because water-based ink used for the printing does not use an organic solvent which is the cause of an odor, and which raises absolutely no hygienic problems. <P>SOLUTION: This packaging container 10 is formed by molding a synthetic resin sheet 20. The sheet 20 comprises a base material sheet and a film heat laminated on the sheet by an extruder or hot laminating machine through a water-based ink. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a packaging container formed by molding a synthetic resin sheet.

  BACKGROUND ART In recent years, foods such as lunch boxes and desserts sold at convenience stores and supermarkets have been put in so-called plastic packaging containers. Such plastic packaging containers are most convenient as food containers because they are provided in large quantities and at low cost, are disposable, and are hygienic.

  As a plastic for forming such a container, a single non-laminated synthetic resin sheet may be employed, but the gas barrier property is enhanced (for example, see Patent Literature 1) or a foamed portion is used. Synthetic resin sheets in which plastic sheets or films are "laminated" have been increasingly employed in order to be able to perform heat insulation and liquid leakage blocking by films.

  In order to laminate a plastic sheet or a film, an adhesive is required. As the adhesive, for example, as described in Patent Literature 2, "a laminating process mainly comprising a pigment, a resin and an organic solvent" There is "ink". The above organic solvent may remain in the synthetic resin sheet laminated using such an ink, and this organic solvent may be diverged to cause an odor.

  In addition, printing for content display and decoration of the packed food is directly printed on this type of synthetic resin sheet to enhance its value as a food container. Conventionally, printing for decoration and display of contents is performed by using a so-called "oil-based ink". In this oil-based ink, a solvent such as ethyl acetate, toluene, and methyl ethyl ketone is used. It is included. In general, these solvents such as ethyl acetate, toluene, and methyl ethyl ketone tend to remain on the synthetic resin sheet after printing is completed.

  When a synthetic resin sheet printed with such an oil-based ink is used to manufacture a packaging container for food, a solvent such as ethyl acetate, toluene, or methyl ethyl ketone remaining in the printed portion may cause a problem. Odor is generated. The unpleasant odor of the solvent alone may not only cause anxiety about the food, but also cause the taste of the food to deteriorate.

  Furthermore, since oil-based inks that have been used conventionally have high viscosity, when printing such as gravure printing is performed, the oil-based inks must be deeply applied to the intaglio and also easily accumulate in the intaglio. For this reason, when performing gravure printing on a synthetic resin sheet with oil-based ink, not only maintenance is troublesome, but also oil-based ink may not be printed neatly on the synthetic resin sheet.

The present inventors, for this type of food packaging container, how to avoid the off-flavor due to the adhesive for lamination or the solvent in the printed ink, and how to improve the printing As a result of various studies on the above, it has been found that it is preferable to use a "water-based ink" as proposed in, for example, Patent Document 3 or Patent Document 4, and the present invention has been completed. is there.
JP 2002-273815, Abstract Japanese Patent Publication No. 7-113098, Claims Patent Publication No. 30233381, paragraph 0007 JP-A-10-67093, abstract

  The present invention has been made on the basis of the above circumstances, and an object to be solved is to provide a packaging container in which the printing of decorations and the like is beautiful and the problem of generation of an unpleasant odor does not occur at all. It is in.

In order to solve the above problems, first, means adopted by the invention according to claim 1 will be described with reference numerals used in the description of the embodiments described below.
"The packaging container 10 formed by molding the synthetic resin sheet 20,
The synthetic resin sheet 20 is formed by laminating a base sheet 21 and a film 22 laminated on the base sheet 21 with an aqueous ink 23 by an extruder or a heat laminating machine. "
It is.

  That is, the packaging container 10 of the present invention is intended for a container body, a lid fitted to the container body, or an integral body thereof, but is formed by molding a synthetic resin sheet 20. It was done. The synthetic resin sheet 20 which is a material of the packaging container 10 is formed by laminating a base sheet 21 and a film 22 with an aqueous ink 23 interposed therebetween. That is, as shown in FIGS. 3 and 4, the water-based ink 23 is printed between the base sheet 21 and the film 22 constituting the synthetic resin sheet 20. What is printed is the water-based ink 23 containing alcohol and water, which has excellent wettability to the film 22, so that not only can it be printed easily at normal temperature on the film 22 and the like, but also because it can be printed at normal temperature, the solvent (water (Alcohol and alcohol) concentration hardly changes, the water-based ink 23 is neatly placed on the intaglio plate for gravure printing, and the water-based ink 23 can be clearly transferred to the film 22.

  In other words, the water-based ink 23 is most suitable for gravure printing, which has low viscosity because of containing water, and has a glossy surface and clear printing. It is used in such a manner that excess ink 23 is removed from the plate making by a doctor blade. Further, since the water-based ink 23 has a low viscosity, it can be thinly mounted on a gravure-printed intaglio plate (about half that of the oil-based ink) as compared with the conventional oil-based ink 23 containing an organic solvent, and provides stable printing. Work can be done.

  The water-based ink 23 contains water and alcohol, and a pigment and an acrylic or urethane-based thermoplastic resin component as described in Patent Document 4, and causes an unpleasant odor. No organic solvent is used. In addition, after laminating the film 22 on the base material sheet 21 with an extruder such as an extrusion lamination or a heat laminating machine such as a stretch lamination, the water-based ink 23 contains almost all of the resin. Causes molecular heat welding of the base sheet 21 and the film 22. For this reason, not only the base sheet 21 and the film 22 are firmly welded, but also water and alcohol hardly remain in the synthetic resin sheet 20 formed using the water-based ink 23. It is. If the sheet 21 and the film 22 are formed of the same type of material, they can be welded without using an adhesive.

  Of course, the pigment contained in the water-based ink 23 remains between the base sheet 21 and the film 22 as it is and does not go outside, so that it exhibits a beautiful pattern as shown in FIG. It does not elute into food. Since the aqueous ink 23 is confined between the base sheet 21 and the film 22, so long as the base sheet 21 or the film 22 is not broken at the time of handling the packaging container 10 or the like. Thus, the aqueous ink 23 or the pigment constituting the same does not peel off.

  Therefore, the packaging container 10 according to the first aspect has a beautiful print of decorations and the like, and does not cause any sanitary problems due to the print.

In order to solve the above-mentioned problems, a means adopted by the invention according to claim 2 is a packaging container 10 according to claim 1,
"The water-based ink 23 is composed of 1 to 30% of alcohol, water, pigment, and resin."
It is.

  That is, the packaging container 10 according to the second aspect employs the aqueous ink 23 used therein that is composed of 1 to 30% of alcohol, water, pigment, and resin. However, the reason why the alcohol needs to be in the range of 1 to 30% is that, when the alcohol is less than 1%, molecular heat welding between the base sheet 21 and the film 22 cannot be sufficiently performed. Because. On the other hand, if the proportion of alcohol is more than 30%, the amount of alcohol not used for molecular thermal welding increases after lamination by an extruder or a heat laminating machine via the aqueous ink 23, and the residual alcohol remains. Is a non-negligible amount.

  As the alcohol, isopropylene alcohol, ethyl alcohol, methanol, and propanol are employed.

  Therefore, the packaging container 10 according to the second aspect has the same effect as that of the first aspect, and furthermore, the remaining of the alcohol is suppressed as much as possible, whereby the generation of the unpleasant odor is further suppressed. It is.

In order to solve the above-mentioned problems, the means adopted by the invention according to claim 3 relates to the packaging container 10 according to claim 1 or claim 2,
"The molding of the synthetic resin sheet 20 is thermoforming of vacuum or pressure forming."

  That is, in the packaging container 10 according to the third aspect, the molding of the synthetic resin sheet 20 in which the base sheet 21 and the film 22 are laminated via the aqueous ink 23 is performed by thermoforming of vacuum or pressure forming. It is. According to this thermoforming, molding can be performed without hindering the above-mentioned molecular thermal welding, and when the synthetic resin sheet 20 is formed into the packaging container 10, the base sheet 21 and the film 22 are bonded together. No separation between them occurs.

  In this case, if a material in which the base sheet 21 and the film 22 are formed of the same kind of resin is adopted, as shown in FIG. Of course, in the portion where the aqueous ink 23 exists, as shown in FIG. 3, the resin component in the aqueous ink 23 serves as an adhesive. That is, the synthetic resin sheet 20 composed of the base sheet 21 and the film 22 is firmly welded and adhered to any part, and there is a portion that partially expands during the thermoforming of the packaging container 10. Even if the packaging container 10 is stored for a long period of time, it is possible to perform stable molding without a peeled portion, and the effect of not peeling is not impaired.

  If the adhesive strength by the resin component in the aqueous ink 23 is increased, the adhesion or welding between the base sheet 21 and the film 22 is strengthened not only on the entire surface of the film 22 but also on a partial print. Is what you can do.

  Therefore, the packaging container 10 according to the third aspect exhibits the same operation as that of the first or second aspect. In addition, for example, in the corner portion of the packaging container 10, the base material sheet 21 and the film 22 No separation between them occurs.

As described above in detail, in the present invention, as exemplified in the above embodiment,
"This is a packaging container 10 formed by molding a synthetic resin sheet 20. The synthetic resin sheet 20 is heat-laminated with a base sheet 21 and an aqueous extruder 23 through an extruder or a heat laminating machine. It was constructed by laminating with the film 22. "
In particular, it has a main feature, whereby the printing of decorations and the like is beautiful, and furthermore, the aqueous ink 23 to be printed does not use an organic solvent that causes an offensive odor, so that no odor is generated, It was possible to provide a packaging container 10 in which no hygiene problem occurs.

  Next, the invention according to each claim configured as described above will be described with respect to a packaging container 10 which is an embodiment shown in the drawings. It substantially includes all such inventions. The packaging container 10 is formed by subjecting a synthetic resin sheet 20 formed by thermally laminating a film 22 to a base sheet 21 via an aqueous ink 23 by thermoforming by vacuum or pressure forming. 1 and 2 as shown in FIG.

  First, a base sheet 21 for forming the synthetic resin sheet 20 is used. As the base sheet 21, a PP (polypropylene) film or sheet of 100 to 2000 μm, preferably 200 to 1000 μm is employed. The film or sheet of the base sheet 21 may be formed of polystyrene paper (medium-impact polystyrene = high-impact polystyrene), or may contain filler.

  As the film 22, a CPP (unstretched polypropylene) film having a thickness of 10 to 100 μm, preferably 15 to 50 μm is used. It may be.

  The aqueous ink 23 is composed of 1 to 30% (preferably 10 to 20%) of alcohol and the remainder of water. As the alcohol, isopropylene alcohol, ethyl alcohol, methanol, or propanol may be used. Just fine. The aqueous ink 23 is to be gravure-printed on the film 22 under the conditions of 10 to 2000 g / m2, preferably 100 to 1000 g / m2.

  If a corona discharge treatment or a framing treatment is performed before printing the water-based ink 23 on the film 22, carbonyl groups and the like can be generated on the surface of the film 22, so that the surface of the film 22 is polarized or hydrophilic. To increase the adhesive strength. Further, it is also possible to form the base sheet 21 and the film 22 from different materials and integrate them with an adhesive to form the synthetic resin sheet 20.

  From the above materials, the following samples according to the examples were prepared, and those to be compared with the examples were selected as follows to form respective synthetic resin sheets, and from these, the packaging container according to the present invention was formed. 10 and a comparative container having a similar shape were formed by thermoforming by vacuum or pressure forming. The lamination strength and the residual solvent were measured for these synthetic resin sheets, the packaging container 10 and the comparative container molded therefrom, and the following results were obtained. In this case, "film adhesion" was confirmed by peeling off the adhesive tape.

単位：Ｎ／２０ｍｍ
ラミネート強度：Ｎ／１５ｍｍ、剥離速度３００ｍ／分、ＭＤ／ＴＤ
［残留溶剤測定］

ＭＥＫ：メチルエチルケトン、ＩＰＡ：イソプロピレンアルコール
単位：ｍｇ／ｍ^２
以上の結果から、本発明に係る包装用容器１０は、比較例と較べて、ラミネート強度や耐油性に優れ、残留溶剤が非常に少なかった。 Example sample: A water-based ink 23 was gravure-printed on an unstretched polypropylene film, and this was extruded and thermally laminated on a polypropylene sheet. Comparative example sample: A commercially available oil-based ink was gravure-printed on an unstretched polypropylene film, and this was marketed. Heat-laminated on a polypropylene sheet containing a filler [Laminate properties]

Unit: N / 20mm
Laminate strength: N / 15mm, peeling speed 300m / min, MD / TD
[Residual solvent measurement]

MEK: methyl ethyl ketone, IPA: isopropylene alcohol Unit: mg / m ²
From the above results, the packaging container 10 according to the present invention was excellent in lamination strength and oil resistance and had very little residual solvent as compared with the comparative example.

It is a top view of the container for packaging concerning the present invention. It is a front view of the packaging container. It is the elements on larger scale sectional drawing of the packaging container seen along the 1-1 line in FIG. FIG. 2 is a partially enlarged cross-sectional view of the packaging container taken along line 2-2 in FIG. 1.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 10 Packaging container 20 Synthetic resin sheet 21 Base sheet 22 Film 23 Water-based ink

Claims (3)

A packaging container formed by molding a synthetic resin sheet,
The packaging container, wherein the synthetic resin sheet is formed by laminating a base sheet and a film laminated on the base sheet with an extruder or a heat laminating machine via an aqueous ink. The packaging container according to claim 1, wherein the aqueous ink is composed of 1 to 30% of alcohol, water, a pigment, and a resin component. The packaging container according to claim 1 or 2, wherein the molding of the synthetic resin sheet is thermoforming of vacuum or pressure forming.

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