JP2020179895A - Paper container - Google Patents

Abstract

To provide a paper container which is formed only by press-molding a sheet of base paper and has an edge wound portion formed on an outer peripheral edge of a side wall portion, and can be used with steam ovens.SOLUTION: A paper container is formed by press-molding base paper 4 in which PET resin layers 3 of low temperature heat sealability with 85% or more of an amorphous part are laminated on both sides of a paper layer 2, and comprises a bottom portion 5, a side wall portion 6 connected to the bottom portion 5, and an edge wound portion 8 formed on an outer peripheral edge of the side wall portion 6. A primary paper container having a plurality of radial winkles creases 9 is formed on a curve corresponding portion, the primary paper container is processed by heating, an overlapping part of the edge wound portion 8 is fixed with molten PET resin and crystallization of the PET resin layers 3 is enhanced so as to impart heat resistance.SELECTED DRAWING: Figure 2

Description

The present invention relates to a paper container compatible with a steam oven.

Paper containers have come to be widely used as containers for accommodating cooked foods and foods to be cooked.
Conventionally, as a paper container for accommodating a cooked product or a product to be cooked, one base paper is formed only by press molding, and is formed on a bottom portion, a side wall portion connected to the bottom portion, and an outer peripheral portion of the side wall portion. A paper plate provided with a rim winding portion is known (see, for example, Patent Document 1).

According to the paper plate described in Patent Document 1, by forming an edge winding portion on the outer peripheral portion of the side wall portion, shape retention is improved by a rib-like action, and the end surface of the base paper forming the paper plate is formed. By preventing the end face from being exposed to the outer peripheral side by entanglement, it is possible to prevent the liquid from seeping into the paper layer from the end face.

In recent years, microwave ovens have been widely used as a means for heating cooked products and products to be cooked, and paper containers laminated with heat-resistant and water-resistant resins are known as paper containers for microwave ovens.
The paper plate described in Patent Document 1 can also be used as a container for accommodating cooked foods and cooked foods to be heated in a microwave oven by forming the base paper laminated with a heat-resistant and water-resistant resin.

Jitsufuku No. 6-6775

As described above, the paper plate described in Patent Document 1 can also be used as a container for a microwave oven by forming it from a base paper laminated with a heat-resistant and water-resistant resin, but the microwave oven is a steam oven. In the case, as shown in FIG. 4, the superheated steam generated by steam heating passes between the overlapping portions C of the edge winding portion 10 and enters the edge winding portion 10 (arrow in the figure), and the edge winding portion 10 There is a problem that the paper layer 11 is soaked from the end surface 11a exposed inside, the paper layer 11 is loosened, the edge winding portion 10 is rewound, and the shape retention property is deteriorated.

As a result of repeated studies to solve such a problem, the present inventor presses using a base paper in which a PET resin layer having a low-temperature heat-sealing property with an amorphous portion of 85% or more is laminated on both sides of the paper layer. We have found that a paper container is formed by molding to form a primary paper container, and the primary paper container is further heat-treated, and the present invention has been completed.

An object of the present invention is to provide a paper container in which one base paper is formed only by press molding and an edge winding portion is formed on the outer peripheral edge of the side wall portion, which is compatible with a steam oven. is there.

In order to achieve the above object, the invention according to claim 1 is pressed by using a base paper in which a PET resin layer having an amorphous portion of 85% or more and having a low temperature heat seal property is laminated on both sides of the paper layer. A primary paper container having a bottom portion, a side wall portion connected to the bottom portion, and an edge winding portion formed on the outer peripheral edge of the side wall portion by molding, and having a plurality of radial squeezed wrinkles is formed in a curved portion. The primary paper container is heat-treated to fix the overlapping portion of the edge winding portion with the molten PET resin, and the PET resin layer is enhanced in crystallization to impart heat resistance.

According to the invention of claim 1, a primary paper container formed by laminating a PET resin layer having a low-temperature heat-sealing property with an amorphous portion of 85% or more on both sides of the paper layer is formed at a low temperature. By heat treatment, the laminated PET resin is melted, and the melted PET resin fills the gap in the overlapping portion of the rim winding portion, so that the overlapping portion of the rim winding portion is fixed and exposed in the rim winding portion. The end face of the paper layer that had been used is surely closed by the molten PET resin, and even when used in a steam oven, the superheated steam generated by steam heating is prevented from seeping into the end face of the paper layer inside the rim winding part. , The overlapping part of the PET resin layer that is in pleated contact due to the radial squeezing wrinkles in the curved part is fixed by the molten PET resin and prevents the wrinkles from growing, so that the shape retention is surely maintained and further. Can enhance shape retention.
Further, since the PET resin layer is crystallized by heat treatment to provide heat resistance, a paper container suitable for high temperature heating by a steam oven can be obtained.

The invention according to claim 2 is characterized in that the heat treatment according to claim 1 is heated in a drying oven maintained at a temperature of 150 to 180 ° C. for 20 to 30 seconds.

According to the invention according to claim 2, since the heat treatment was performed in a drying furnace maintained at a temperature of 150 to 180 ° C. for 20 to 30 seconds, the laminated PET resin was surely melted and described above. A PET resin that fills the gaps in the rim winding portion, the overlapping portion of the rim winding portion is firmly fixed, and the overlapping portion of the PET resin layer that is in pleated contact due to radial squeezing wrinkles in the curved portion is melted. Therefore, it can be firmly fixed, and the crystallization of the PET resin layer can be enhanced to reliably impart heat resistance.

As described above, according to the paper container according to the present invention, it is possible to prevent loosening of the paper layer and rewinding of the edge winding portion due to superheated steam generated by steam heating, and a paper container suitable for a steam oven can be obtained. be able to.

It is a front view of the partial vertical section which shows an example of embodiment of the paper container which concerns on this invention. It is explanatory drawing which shows the state which the molten PET resin fills the gap of the edge winding part, and the overlapping part of the edge winding part is fixed. It is explanatory drawing which shows the state which the overlapping part of the PET resin layer which is in contact with pleats by the squeezing wrinkle in the curve corresponding part is fixed by the molten PET resin. It is explanatory drawing which shows the state which superheated steam enters into the edge winding part from the overlapping part of the edge winding part of the conventional paper container.

Hereinafter, an example of the embodiment of the paper container according to the present invention will be described in detail with reference to the drawings.
1 to 3 show an example of an embodiment of a paper container according to the present invention, FIG. 1 is a front view of a partial vertical cross section of the paper container of this example, and FIG. 2 is a rim wrapped with molten PET resin. Explanatory drawing showing a state in which the overlapping portion of the edge winding portion is fixed by filling the gap of the portion, FIG. It is explanatory drawing which shows the fixed state.

The paper container 1 of this example uses a base paper 4 in which a PET resin layer 3 having an amorphous portion of 85% or more and having a low temperature heat seal property is laminated on both sides of the paper layer 2.
In this example, the melting temperature of the PET resin layer 3 having an amorphous portion laminated on both sides of the paper layer 2 of 85% or more is set to 130 ° C.
In the base paper 4 in which the PET resin layer 3 having an amorphous portion of 85% or more is laminated on both sides of the paper layer 2, in this example, it is for a paper container disclosed in Japanese Patent Application Laid-Open No. 2012-666506. The laminated material is used as the base paper 4.

Then, the base paper 4 is formed by press molding on the bottom portion 5, the side wall portion 6 connected to the bottom portion 5, the flange portion 7 connected to the side wall portion 6 and extending in the horizontal direction, and the outer peripheral edge of the flange portion 7. A primary paper container having a plurality of radial squeezed wrinkles 9 is formed in a curved portion, and the primary paper container is heat-treated, and the overlapped portion of the flanged portion 8 is made of molten PET resin. A is fixed, and the crystallization of the PET resin layer 3 is enhanced to impart heat resistance.

In the heat treatment of the primary paper container, it is heated for 20 to 30 seconds in a drying furnace maintained at a temperature of 150 to 180 ° C.
The heating temperature and heating time in the heat treatment can be obtained under the following conditions.
At a heating temperature of 150 to 180 ° C., the PET resin of the PET resin layer 3 laminated on the base paper 4 is melted, and the crystal portion of the PET resin layer 3 after the heat treatment is heat-resistant required for use in a steam oven. It is required as a temperature to raise the crystal portion sufficient to impart.
Further, in the heating time of 20 to 30 seconds, the PET resin of the PET resin layer 3 laminated on the base paper 4 is melted at a heating temperature of 150 to 180 ° C., and the water contained in the paper layer 2 is removed by heating. It is required as a time before evaporation occurs until delamination occurs between the paper layer 2 and the PET resin layer 3.

If the heating temperature is less than 150 ° C. and the heating time is less than 30 seconds, the PET resin of the PET resin layer 3 laminated on the base paper 4 cannot be melted, and the PET resin layer 3 after the heat treatment cannot be melted. The crystalline portion of the above cannot be increased to a crystalline portion sufficient to impart the heat resistance required for the use of a steam oven. Further, when the heating temperature exceeds 180 ° C. and the heating time exceeds 20 seconds, the moisture contained in the paper layer 2 evaporates, and delamination occurs between the paper layer 2 and the PET resin layer 3. In some cases.
Regarding the heating temperature and the heating time in the heat treatment, the heating time of 25 seconds at the heating temperature of 160 ° C. is most preferable.

By heat-treating the primary paper container in this way, the molten PET resin fills the gap of the overlapping portion A of the edge winding portion 8 so that the overlapping portion A of the edge winding portion 8 is fixed (see FIG. 2). ).
Further, the overlapping portion B of the PET resin layer 3 in pleated contact due to the radial squeezing wrinkles 9 in the curved portion is fixed by the molten PET resin (see FIG. 3).

Further, by heat-treating the primary paper container, the crystallization of the PET resin layer is enhanced, and the paper container 1 having high heat resistance is obtained.

According to the paper container 1 configured in this manner, a primary paper container formed by using a base paper in which a PET resin layer 3 having a low-temperature heat-sealing property with an amorphous portion of 85% or more is laminated on both sides of the paper layer 2. Is heat-treated at a low temperature to melt the PET resin of the laminated PET resin layer 3, and the melted PET resin fills the gap of the overlapping portion A of the margin winding portion 8 to fill the gap of the overlapping portion A of the margin winding portion 8. Sticks.

As a result, the end surface 2a of the paper layer 2 exposed in the edge winding portion 8 is closed by the molten PET resin, and even if it is used in a steam oven, superheated steam generated by steam heating is introduced into the edge winding portion 8. It is prevented from penetrating into the end surface 2a of a certain paper layer 2, and the overlapping portion B of the PET resin layer 3 which is in pleated contact with the radial squeezed wrinkles 9 in the curved portion is fixed by the molten PET resin. Since the growth of the wrinkles 9 is prevented, the shape retention of the paper container 1 is maintained, and the shape retention is further enhanced.

Further, the crystallization of the PET resin layer 3 is enhanced by the heat treatment, and a paper container 1 suitable for high temperature heating by a steam oven can be obtained.

When the primary paper container is heat-treated and heated for 20 to 30 seconds in a drying furnace maintained at a temperature of 150 to 180 ° C., the PET resin of the laminated PET resin layer 3 is surely melted and the edge winding portion. The overlapping portion A of the edge winding portion 8 is securely fixed by filling the gap of 8, and the overlapping portion B of the PET resin layer 3 which is in contact with each other in an overlapping manner due to the radial squeezing wrinkles 9 in the curved corresponding portion is melted. The PET resin is surely fixed, and the crystallization of the PET resin layer 3 is enhanced, so that a paper container 1 suitable for high-temperature heating by a steam oven can be obtained.

In particular, regarding the heating temperature and the heating time in the heat treatment, when the heating time was 25 seconds at the heating temperature of 160 ° C., the optimum shape retention and heat resistance as a paper container used in the steam oven were imparted. Paper container 1 is obtained.

1 Paper container 2 Paper layer 2a End face 3 PET resin layer 4 Base paper 5 Bottom 6 Side wall 7 Flange 8 Margin 9 Wrinkle A Overlapping part of edge winding B Overlapping part of PET resin layer in wrinkle

Claims (2)

Using a base paper in which a PET resin layer having a low-temperature heat-sealing property with an amorphous portion of 85% or more is laminated on both sides of the paper layer, the bottom portion, the side wall portion connected to the bottom portion, and the side wall portion are formed by press molding. A primary paper container having a marginal winding portion formed on the outer peripheral edge and having a plurality of radial squeezed wrinkles is formed in a curved portion, the primary paper container is heat-treated, and the marginal winding is made of molten PET resin. A paper container characterized in that the overlapping portions of the portions are fixed and the PET resin layer is crystallized to be imparted with heat resistance. The paper container according to claim 1, wherein the heat treatment is performed by heating for 20 to 30 seconds in a drying oven maintained at a temperature of 150 to 180 ° C.