JP3924818B2 - Paper tray container - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tray-like container in which a synthetic resin film is integrated by vacuum molding or the like on the inner surface of an outer container whose base material is paper that is filled with uncooked and cooked food.
[0002]
[Prior art]
As a container for storing frozen foods and the like, for example, as shown in Japanese Patent Publication No. 52-4315, a tray-like container in which a blank made of a paperboard coated with a synthetic resin is assembled has been proposed and put into practical use.
This tray-like container is coated with synthetic resin on the inner surface and is folded and molded so as to be overlapped so that the end face of the blank is not exposed at the corner portion. It could also be used for the contents.
[0003]
On the other hand, in recent years, such a paper tray-shaped container is filled with sealed food or semi-cooked food and sealed, and when used, the tray-shaped container is directly heated or cooked by a microwave oven or oven. However, there is a demand to use it as it is as a tableware.
Therefore, as the synthetic resin provided on the inner surface, polypropylene having both heat resistance and heat sealing properties is suitable, and in order to withstand the heating process, it is preferable to use a film of 100 μm or more.
[0004]
However, when a synthetic resin film made of a polypropylene film having the above thickness is used on the inner surface of the tray-like container, it is difficult to fold and form at the corner portion, and occurs when the corner portion is folded and formed. There was a step in the flange part, and it was difficult to seal the flange part after storing the contents.
[0005]
Also, for example, as shown in Japanese Utility Model Publication Nos. 51-31202 and 54-42830, a synthetic resin resin film is heat-softened on the inner surface of a paper outer container and laminated and bonded by means such as vacuum forming. A tray-shaped container has been proposed.
This tray-like container can be made into a structure in which a step does not occur in the flange portion, and can be used as a container having good sealing performance.
[0006]
However, such a tray-like container is a stage where the synthetic resin film comes into contact with the outer container when the outer container is placed in a mold and the heat-softened synthetic resin film is integrated by vacuum molding or the like. As a result, it was cooled immediately, and sufficient adhesive strength with the outer container could not be obtained.
In particular, in the case of a polypropylene film having heat resistance and heat sealability, satisfactory adhesive strength was not obtained.
[0007]
[Problems to be solved by the invention]
Thus, if the adhesive strength with the outer container is weak, after the contents are stored in the tray-like container, after sealing with the lid material, when opening the lid material during heating or cooking, the outer container is integrated. There was a possibility that the inconvenience that the synthetic resin film was peeled off occurred.
Therefore, a tray-like container having a good sealing property in which the heat-softened polypropylene film as described above is integrated on the inner surface of the paper outer container by means of vacuum forming or the like. There is a need for a tray-like container with increased adhesive strength.
[0008]
[Means for Solving the Problems]
The first invention of the present invention is a paper comprising a tray material and a lid material that is sealed and sealed with a paper-based lid material after filling the contents in a paper- based tray-like container. in manufacturing the tray-like container, said tray-like container, while opening the upper surface, the inner surface of the outer container made of paper substrate having a flange surface on the opening edge, the ethylene copolymer layer having at least a polypropylene layer and a carbonyl group And the synthetic resin film having the carbonyl group as the outer container side, and being laminated and integrated by vacuum forming or a combination of vacuum forming and pressure forming , the flange The surface is a polypropylene layer surface, and the lid is made of polyethylene or ethylene-α-olefin copolymer polymerized by a single site catalyst or a single site on one side of a paper substrate. A plastic synthetic resin layer made of polyethylene polymerized with a medium or polyethylene polymerized with a multi-site catalyst on an ethylene-α olefin copolymer, or a resin obtained by mixing an ethylene-α olefin copolymer with polyethylene polymerized with a single site catalyst is laminated. A paper tray-like container , wherein a peeled synthetic resin layer surface of the lid material is superposed on a polypropylene layer surface of a flange surface of the tray-like container, and the superposed inner surface is heat-sealed and sealed. It is.
[0009]
The second aspect of the present invention, in the above-mentioned paper tray-like container of the first invention, the polypropylene layer of the synthetic resin film to be laminated adhered to the outer container inner surface, paper tray-like container was in the range of 100μm~200μm It is. According to a third aspect of the present invention, in the first or second aspect of the invention, the polypropylene layer of the synthetic resin film that is laminated and adhered to the inner surface of the outer container is either polypropylene alone or a mixture of polypropylene and an ethylene resin. This is a paper tray-like container made of the above resin.
[0010]
A fourth invention of the present invention is the paper tray-shaped container according to any one of the first to third inventions, wherein the synthetic resin film laminated and adhered to the inner surface of the outer container is a coextruded film . According to a fifth aspect of the present invention, in the fourth aspect, the synthetic resin film that is laminated and adhered to the inner surface of the outer container is a two-layer structure comprising the polypropylene layer and an ethylene copolymer layer having a carbonyl group, or Paper which is a co-extruded film with a multilayer of a polypropylene layer and a resin layer of a single layer of polypropylene, polyethylene, or amorphous polyester, or a combination of these single layers and an ethylene copolymer layer having a carbonyl group A tray-shaped container.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described. As shown in FIG. 1, the present invention is a paper tray-like container 10 used as a paper container sealed with a lid member 20.
The tray-like container 10 includes a pair of side plates 2 and 2 that face the four sides of the rectangular bottom plate 1 and incline outward toward the upper side, and another pair of side plates 3 and 3.
And, each of the side plates 2 and 2 is provided with an inverted isosceles triangular triangular corner plate 6 and a superposed piece 7 on the side of the side plates 2 and 2, and by superposing the superposed piece 7 on the inner side edges of the side plates 3 and 3, A corner portion formed by a triangular corner plate is provided.
Further, a flange 4 is provided on the upper ends of the side plates 2 and 2 so as to extend outwardly horizontally, and a flange 5 is provided on the upper end of the side plate 3 so as to extend horizontally outwardly. A flange 8 projecting horizontally outward is provided above the triangular corner plate 6.
[0012]
Then, the synthetic resin film 40 is laminated and bonded to the inner surface of the paper tray-like container 10 by vacuum forming or a combination of vacuum forming and pressure forming.
Further, the bottom surface plate 1, the side surface plates 2, 2 and the side surface plates 3, 3, the triangular corner plate 6, the entire surface outside the flanges 4, 5, and 8, or partially the printing layer 30 of the tray-like container 10. Is provided.
[0013]
The tray-like container of the present invention can further be provided with a cover material. That is, the end side of the lid member is connected to the upper part of the one side plate of the tray-like container via the broken line.
Further, as shown in FIG. 4, the tray-shaped container may not have the triangular corner plate 6. In order to obtain the rigidity of the tray-like container, it is necessary to overhang and provide a polymer piece that overlaps adjacent side plates. Moreover, it is necessary to overlap the polymer pieces on the inner surface of the adjacent side plate. This is because, in this state, the synthetic resin film is laminated and bonded, and when the synthetic resin film is integrated, the polymer piece is also bonded by the synthetic resin film.
Further, the tray container may be a polygonal tray container such as an octagonal tray container as shown in FIG.
[0014]
On the other hand, the lid member 20 that seals the opening of the tray-like container is a paper lid member having a shape and size that matches the flanges 4, 5, and 8 of the tray-like container 10, and a synthetic resin film is laminated on the inner surface. The printed layer 30 is provided on the entire outer surface or an appropriate portion by bonding.
The lid member 20 can also have various shapes depending on the tray container.
[0015]
And after filling the said tray-shaped container 10 with a foodstuff, the said cover material 20 is piled up on the flanges 4, 5, and 8 of this tray-shaped container 10, and the synthetic resin films of the inner surface of both members are heat-seal | fused. Seal and seal for use.
[0016]
In the present invention, it is necessary to provide the synthetic resin film 40 only on the inner surfaces of the tray-like container 10 and the lid member 20 as shown in FIG. This is caused by the phenomenon that when the container is heated by a microwave oven, an oven or the like, the moisture of the paper 50 as a base material is boiled and evaporated and appears on the surface of the paper. For this reason, when a synthetic resin film is provided on both sides of the paper, there arises a problem that the adhesion between the paper and the synthetic resin film is peeled off by the vapor.
At this time, if a synthetic resin film having a low melting point is disposed, there arises a problem that the synthetic resin film foams due to melting of the synthetic resin film itself and ejection of the vapor.
[0017]
Therefore, in the present invention, the synthetic resin film is provided only on the inner surface of the paper base material and is not provided on the outer surface so that the release of the vapor is not hindered. In addition, when a synthetic resin film is also arranged on the outside, another means that does not hinder the release of such vapor is possible by laminating and bonding a highly breathable synthetic resin film, such as having fine through holes. is there.
[0018]
Said tray-like container 10, as the paper substrate 50 used in the lid 20 has a moderate stiffness (e.g., basis weight 200-500 g / m ^2), of course, rigidity against heat by microwave, oven, etc. Therefore, it is necessary to use a low-quality material that does not generate odor due to heating. A material made of virgin pulp is suitable as a material that satisfies this requirement. In addition, it is necessary to use a material that is water resistant and has no absorbability of moisture adhering from the end face or a low material because it is necessary to prevent the moisture adhering to cooking. A material generally called cup base paper is suitable as a material that satisfies this requirement.
[0019]
These required qualities are intended to prevent deterioration of the container due to condensation on the surface of the sealed paper container when it is frozen and refrigerated in a refrigerator, etc., and before the consumer purchases and takes it away from the storage state. It will also be effective. Moreover, oil resistance can also be given as needed.
Furthermore, it is necessary that the material does not peel off in terms of peel strength from the lid when opened.
[0020]
The synthetic resin film 40 used for the tray-like container 10 is excellent in water resistance, maintains sufficient hermeticity during storage such as refrigeration after filling and sealing the contents, and is excellent in heat-fusibility. In addition, resistance to heating such as a microwave oven and an oven is required. That is, high water resistance and heat resistance are required.
[0021]
For example, the layer in contact with the contents is polypropylene (PP), specifically, homopolypropylene, random polypropylene copolymer, or block polypropylene copolymer, and it is particularly preferable to use random polypropylene copolymer.
The layer in contact with the outer container is a synthetic resin film composed of at least two layers using an ethylene copolymer layer having a carbonyl group.
The thickness of the synthetic resin film is required to be 100 μm or more for moldability, heat resistance, and content protection, and is preferably in the range of 100 to 200 μm.
[0022]
Specific examples of the ethylene-based copolymer containing a carbonyl group include an ethylene-methyl methacrylate copolymer, an ethylene-vinyl acetate copolymer, or an ethylene-acrylic acid ester-maleic anhydride terpolymer. Raised.
In addition to the above-described structure, the synthetic resin film 40 may have a multilayer structure in which PP layers other than a single PP are combined with PP, polyethylene, or amorphous polyester other than PP used on the side in contact with the contents. Good.
Each of the synthetic resin films may be laminated by a dry laminating method, but a film formed by a coextrusion method in which melt extrusion is simultaneously performed is preferable.
[0023]
On the other hand, the lid material that seals the opening of the tray-shaped container needs to have both a sealing property and an opening property, and a peelable resin is laminated as a synthetic resin film in order to improve the easy opening property at the time of opening. Is preferred.
As this peelable resin, polyethylene polymerized by a single site catalyst, ethylene-α olefin copolymer, polyethylene polymerized by a single site catalyst, polyethylene polymerized by ethylene-α olefin copolymer by a multi-site catalyst, or It is preferable to use a resin in which an ethylene-α-olefin copolymer is mixed.
[0024]
When the printing layer 30 is provided on the tray-like container 10, the ink needs to have resistance to heating by a microwave oven, an oven, or the like. That is, high heat resistance is required. Further, it is necessary that odor is not generated or low due to heating. Furthermore, air permeability is required in order not to hinder the release of vapor from the paper due to the heating described above.
[0025]
The printing layer 30 used in the tray-like container 10 can be provided with an overcoat varnish (OP varnish) 32 on the outermost surface of the printing layer in addition to the ink 31 for pattern formation. By providing this OP varnish, when producing a tray-like container, the synthetic resin film is laminated with a paper base material and integrated in a mold by vacuum forming or vacuum / pressure forming in combination. By providing the OP varnish, it becomes easy to take out the tray-like container from the mold, and it is possible to prevent deformation and destruction of the tray-like container in the taking-out process. Also, this OP varnish needs to have heat resistance, air permeability and generation of odor due to heating at the same time as other inks.
[0026]
【The invention's effect】
Since this invention is the above structure, there exist the following effects.
That is, the inner surface of a paper tray container was provided with an ethylene-based copolymer having at least PP as a layer in contact with the contents and a carbonyl group as a layer in contact with the outer container by vacuum forming or combined use of vacuum forming and pressure forming. Since a synthetic resin film is used, the inner surface of the tray-like container has complete water resistance, so it is possible to store foods containing liquids and moisture, and the contents can be heated without changing the container in a microwave oven, oven, etc. Because cooking is possible, it is possible for consumers to easily cook without preparing cooking utensils such as pans, and since these containers are not damaged by cooking, they can be used as they are as tableware. It became.
[0027]
And since the layer of the synthetic resin film in contact with the outer container is an ethylene-based copolymer having a carbonyl group, the synthetic resin film is softened by heating, and means such as vacuum forming on the outer container at room temperature or lower Therefore, even if lamination is integrated, the adhesive strength between the outer container and the synthetic resin film can be maintained.
[0028]
Thereby, when opening a cover material, the synthetic resin film integrated with the outer container does not peel from the outer container.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of the present invention.
FIG. 2 is a plan view showing the same embodiment of the present invention.
FIG. 3 is a cross-sectional view showing the same embodiment of the present invention.
FIG. 4 is a plan view showing a second embodiment of the present invention.
FIG. 5 is a plan view showing a third embodiment of the present invention.
[Explanation of symbols]
10 ... Tray container 20 ... Cover 30 ... Print layer 31 ... Ink for pattern formation
32 ... OP varnish 40 ... Synthetic resin film 50 ... Paper base material 1 ... Bottom plate 2, 3 ... Side plates 4, 5, 8 ... Flange
6 …… Triangle corner plate 7 …… Polymerized piece

Claims (5)

In a paper tray-like container composed of a lid material and a tray-like container that is sealed and sealed with a paper-based lid material after filling the contents in the paper- like tray-like container , the tray-like container container, while opening the upper surface, the inner surface of the outer container made of paper substrate having a flange surface on the opening peripheral edge, a synthetic resin film having an ethylene copolymer layer having at least a polypropylene layer and a carbonyl group, wherein The ethylene-based copolymer layer having a carbonyl group is used as the outer container side, and is laminated and integrated by vacuum forming or a combination of vacuum forming and pressure forming, and the flange surface is a polypropylene layer surface, and the lid The material is a polyethylene or ethylene-α olefin copolymer polymerized by a single site catalyst, or a polymer polymerized by a single site catalyst on one side of a paper substrate. A plastic synthetic resin layer comprising a polyethylene polymerized with a multi-site catalyst on a ethylene or ethylene-α olefin copolymer or a resin obtained by mixing an ethylene-α olefin copolymer with a polyethylene polymerized with a single site catalyst is laminated, and the tray polypropylene layer surface of the flange surface of the Jo container, the Pirapuru synthetic resin layer surface of the lid are superimposed, paper tray-like container whose superposition inner surface, characterized in that it is sealed are heat sealed. The paper tray-like container according to claim 1, wherein the polypropylene layer of the synthetic resin film laminated and adhered to the inner surface of the outer container is in the range of 100 µm to 200 µm. The paper tray shape according to claim 1 or 2, wherein the polypropylene layer of the synthetic resin film laminated and adhered to the inner surface of the outer container is made of polypropylene alone or a resin obtained by mixing polypropylene with an ethylene-based resin. container. Synthetic resin film to be laminated adhered to the outer container inner surface, a coextruded film, paper tray-like container according to any one of claims 1 to 3. The synthetic resin film that is laminated and adhered to the inner surface of the outer container is a double layer of the polypropylene layer and an ethylene-based copolymer layer having a carbonyl group, or any one of the polypropylene layer and polypropylene, polyethylene, or amorphous polyester. The paper tray-like container according to claim 4, which is a co-extruded film having a multilayer of a resin layer having a multilayer structure obtained by combining layers or a single layer thereof and an ethylene-based copolymer layer having a carbonyl group .

Images