JP4580504B2 - Method for producing sealed paper tray container - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealed paper tray container and a method for manufacturing the same, and more particularly to a sealed paper tray container in which a flange portion is formed on a smooth surface and a seal lid is heat-sealed and a method for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a container formed by forming paper into a dish (tray) has been used as a disposable container. Further, containers deeply molded with paper, so-called deep-drawn paper trays, have been put into practical use. In this deep-drawn paper tray, the flange part is a paperboard blank with a thermoplastic resin layer made of a heat-resistant resin laminated on the surface, or a blank with a crease in advance on the flange part, using an uneven mold. It was formed by a molding method of narrowing down with heat and pressure.
[0003]
In general paper plates (paper trays), the aperture is shallow, and it is difficult to wrinkle as a whole during molding, and a flange portion (peripheral portion) with less unevenness can be obtained. However, when the aperture is deepened, the flange portion 3 is likely to be wrinkled, and the surface of the flange portion 3 becomes an uneven surface, and the seal lid is heat-sealed in this state.
[0004]
[Problems to be solved by the invention]
However, in the deep-drawn paper tray formed by the above technique, when a seal lid is placed on the flange portion, because the drawing wrinkles accompanying the molding remain in the flange portion, the flange portion is not a sufficiently smooth surface. It is difficult to sufficiently seal the contents stored in the paper tray with the sealing lid applied. In addition, even if the flange portion is preliminarily stamped at the blank stage, there is a problem that squeezing is generated by molding and it is difficult to obtain high sealing performance even if heat sealing is performed with a seal lid. .
[0005]
In contrast, the present invention solves the above-described problems of the conventional deep-drawn paper tray container, and is mainly made of paperboard in which a thermoplastic resin layer made of a polyethylene resin having a low heat deformation temperature is laminated on the inner surface. In the deep drawing paper tray molding process, the flange part is crushed by using low temperature and pressure to form a smooth surface with few irregularities, and then sealed by heat sealing the sealing lid later It is an object of the present invention to provide a sealed paper tray container having a flange portion capable of high-performance sealing and a method for manufacturing the same.
[0006]
[Means for Solving the Problems]
The present invention has been studied to solve the above problems, and as a result, a polyethylene resin layer consisting of a low-density polyethylene resin or a medium-density polyethylene resin, paper, and an outermost layer consisting of polypropylene, polyethylene terephthalate or methylpentene polymer. A laminate blank consisting of three layers, or a polyethylene blank composed of two layers of a low-density polyethylene resin or a medium-density polyethylene resin and a two-layer paper blank, with the polyethylene resin layer on the inner surface side. A method of manufacturing a sealed paper tray container comprising a paper tray having a molded flange portion and a sealing lid heat-sealed to the flange portion, wherein the flange portion is a region to be the flange portion at the corners of a polygonal corner In the region that becomes the side, a plurality of ruled lines are provided from the outer peripheral edge toward the center of the arc, The temperature of the mold female molding a serial tray in the range of 150 to 200 ° C., the thermal deformation temperature of the resin of the temperature of the male mold the polyethylene emission resin layer (JIS K-7207) than the 10 ° C. or higher temperature lower The method for producing a sealed paper tray container, characterized in that after forming and filling the contents, the sealing lid is heat-sealed, has been found and completed.
[0008]
According to the present invention, in the process of molding a blank mainly made of paperboard in which a thermoplastic resin layer made of a resin having a low thermal deformation temperature of polyethylene resin is laminated on the inner surface (surface) into a sealed paper tray container, the flange portion is Using a low temperature and pressure, crushing to form a smooth surface with little unevenness due to squeezing wrinkles, and then heat sealing the sealing lid, the inner surface of the flange portion of the molded paper tray has a low thermal deformation temperature Since it is a thermoplastic resin layer made of resin, a squeezed wrinkle generated in the flange portion at the time of heat sealing is crushed, and a gap between irregularities is filled to obtain a sealed paper tray container capable of high sealing performance Can do.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings.
As shown in FIG. 1, a sealed paper tray container A having a flange portion capable of high sealing performance by heat sealing the seal lid of the present invention comprises a paper tray 1 and a seal lid 20. The paper tray 1 is produced by press-molding a blank 11 whose main material is a paperboard in which a thermoplastic resin layer made of a resin having a low thermal deformation temperature of polyethylene resin is laminated on the inner surface (surface). A paper tray 1 is a deep-drawn paper tray comprising a square bottom surface 4 with rounded corners, a side surface 3 formed at the outer periphery thereof, and a flat flange portion 2 formed over the entire periphery of the upper end of the side surface 3. It is. The corners of the four corners are in a state where a plurality of wrinkles generated by squeezing during press molding are generated. The aperture wrinkles 5 are generated along the stamped lines provided in advance at the corners of the blank.
[0010]
Although the flange portion 2 is formed on the outer periphery of the paper tray 1, the outer peripheral end portion of the flange portion 2 can be curled to improve the shape retention as a paper tray.
The shape of the paper tray 1 is not particularly limited as long as it has the flange portion 2 such as a quadrangle, pentagon, hexagon, or circle.
[0011]
As shown in FIG. 2, the blank 11 before the paper tray 1 is manufactured by press molding is a rounded rectangle, and the region 12 that becomes the flange portion 2 at the corners of the four corners or the region 13 that becomes the side surface 3. Are provided with a plurality of ruled lines 15 from the outer peripheral end toward the center of the arc. By providing a plurality of creases 15 with a narrow interval in this way, the drawability of the corners of the paper tray 1 during press molding is improved, and the shape retention of the molded paper tray 1 is improved. be able to.
[0012]
The constitution of the material used for the paper tray 1 of the sealed paper tray container A of the present invention is based on the fact that paper is the main strength material and at least the inner surface (surface) has a thermoplastic resin layer.
[0013]
The thermoplastic resin layer on the inner surface is laminated with a thermoplastic resin layer made of a resin having a low thermal deformation temperature of polyethylene resin, the function of protecting the contents, in particular, a function that does not leak even if a liquid substance is added, It is necessary to have functions such as sealability with the lid material of the seal lid 20, moldability, and heat resistance by heat sealing. By forming a thermoplastic resin layer made of this polyethylene resin having a low heat distortion temperature, the paper tray 1 can be molded by changing the thermal conditions of the mold using a conventional molding machine. The squeezed wrinkles 5 generated in the flange portion 2 of the formed paper tray 1 are melted by heat by heat sealing of the seal lid 20 to close the uneven gaps, so that a sealed paper tray container A with high sealing performance is obtained. .
[0014]
Polyethylene resins are usually classified as low density polyethylene, medium density polyethylene, and high density polyethylene depending on their density. Polyethylene resin is inexpensive and excellent in water resistance, and as its density increases, heat resistance, that is, heat deformation temperature increases, and deformation due to heat and pressure during heat sealing of the seal lid 20 is reduced and molded. It becomes difficult to melt the squeezed wrinkles 5 generated in the flange portion 2 of the paper tray 1 by the heat of the heat seal of the seal lid 20 to close the gaps between the irregularities. Therefore, it is preferable to use low density polyethylene or medium density polyethylene having a low heat distortion temperature.
The thickness of the thermoplastic resin layer is preferably in the range of 15 to 60 μm. These thermoplastic resins are laminated on the surface by extrusion or lamination.
[0015]
As the paper used as the main strength material, it is preferable to use cup base paper, ivory paper, card paper, or the like having good moldability for the paper tray 1. Basis weight is not particularly limited, the moldability of the paper tray 1, the range of 160~400g / m ² is more preferable.
[0016]
A heat-resistant resin layer having water resistance, oil resistance and the like can be provided on the outer surface of the paper. Specific examples include polypropylene (hereinafter abbreviated as PP), polyethylene terephthalate (hereinafter abbreviated as PET), methylpentene polymer (hereinafter abbreviated as TPX), and the like. As thickness, the range of 15-60 micrometers is preferable. These thermoplastic resins are formed on the outer surface by extrusion or lamination.
[0017]
Specific examples of the overall material structure include, for example, from the inner surface side, polyethylene (hereinafter abbreviated as PE) / paper, PE / paper / PP, PE / paper / PET, PE / paper / TPX, PE / paper / PE. / PP, PE / paper / PE / PET, PE / paper / PE / TPX and the like. Of course, printing can be performed on the front or back surface of the paper.
[0018]
The seal lid 20 is appropriately selected depending on the material of the inner surface of the paper tray 1, but preferably has an easy peel property. For example, PET / heat sealing agent, PP / heat sealing agent, PET / PP / heat sealing agent, PET / PE / heat sealing agent, saponified product (EVOH) / PE / PE / PE / ethylene-vinyl acetate copolymer A heat sealing agent, K coat stretched nylon (KON) / PE / heat sealing agent, etc. can be used.
[0019]
The manufacturing method of the sealed paper tray container A having the flange portion 2 capable of sealing with high sealing performance by the seal lid 20 of the present invention will be described. First, as shown in FIG. 2, a blank 11 is formed by punching. It is easier to form the blank 11 by applying a large number of the stamped lines 15 in advance to the wrinkled portion. The stamping rule 15 can be processed simultaneously with the punching process.
[0020]
Next, the structure of the molding machine 30 for producing the sealed paper tray container A of the present invention includes an upper press head 31 and a lower press head 35 as shown in FIG. An upper heater panel 32 is attached to the upper press head 31, and an upper mold frame 33 and an upper mold (female mold) 34 are attached to the upper heater board 32. On the other hand, a lower heater panel 36 is attached to the lower press head 35, and a lower mold frame 37 and a lower mold (male mold) 38 are attached to the lower heater panel 36. The upper die 34 has a shape that matches the outer surface of the bottom surface 4, the outer surface of the side surface 3, and the outer surface of the flange portion 2 of the paper tray 1.
[0021]
In press molding, the temperature of the upper heater panel 32 is set so that the temperature of the upper mold 34 is 150 to 200 ° C. On the other hand, the temperature setting of the lower heater panel 36 is set so that the temperature of the lower mold 38 is at least 10 ° C. lower than the thermal deformation temperature of the resin of the thermoplastic resin layer on the inner surface of the paper tray 1 for forming the paper tray 1. Do. Under these temperature conditions, the upper press head 31 is moved upward so that the thermoplastic resin layer on the inner surface of the paper tray 1, that is, the blank 11, is on the lower surface of the lower mold 38. The upper press head 31 is moved to the lower side and pressed between the lower die 38 and the upper die 34 at a pressure of 5 to 10 kg / cm. Is generated and formed into a paper tray shape as in the mold.
[0022]
Further, after the contents are stored in the formed paper tray 1, the sealing lid 20 is heat-sealed by the flange portion 2 of the paper tray 1, and the sealed paper tray container A is completed. The heat sealing is performed at a temperature higher than the thermal deformation temperature of the thermoplastic resin on the inner surface of the paper tray 1 to melt the thermoplastic resin layer on the surface and block the generated wrinkle 5.
[0023]
FIG. 4 shows a comparison of partial cross sections before and after the process of actually heat-sealing the seal lid 20. FIG. 4A shows a partial cross-sectional state of the flange portion 2 after forming the paper tray 1 from the blank 11. In this state, wrinkles are generated. Liquid content leaks through the part. On the other hand, in the sealed sealed paper tray container A of the present invention after the seal lid 20 is heat sealed, the thermoplastic resin layer 17 on the surface is made of a resin having a low thermal deformation temperature, so that the contents are stored. After that, the sealing lid 20 is heat-sealed, and as shown in FIG. 4B, the surface of the generated wrinkle portion is melted by heat and crushed by pressure, so that the wrinkle tunnel shape is obtained. The portion that is formed is blocked and the liquid does not penetrate, and the surface irregularities are reduced. Therefore, a heat-sealing paper tray container can be obtained by heat-sealing the sealing lid 20.
[0024]
【Example】
An example of a sealed paper tray container manufactured by the method for manufacturing a sealed paper tray container of the present invention was prepared according to the following specifications.
[0025]
Specified shape of paper tray container; square shape (flange part outer dimensions 117mm x 157mm)
Content: 220ml
Flange width: 7mm
Height; 35mm
Material composition: (Inner surface) PE 20 μm / paper 280 g / m ²
PE (Mirason 16P manufactured by Mitsui Petrochemical Co., Ltd.)
A paper tray having the above specifications was produced by molding with the upper mold temperature set at 180 ° C. and the lower mold temperature set at 80 ° C. as the molding machine conditions.
[0026]
Conditions for heat sealing processing Heating temperature; 150 ° C
Pressurizing force: 350 kgf
Hold time: 0.2 seconds Seal lid specification material configuration: PET / PP / heat sealant Next, after filling the paper tray having the flange part with the liquid content, the paper tray flange under the above conditions In the section, the sealing lid was sealed by heat sealing. As a result, it was possible to produce a highly sealed product that does not leak liquid.
[0027]
【The invention's effect】
According to the present invention, in the process of forming a blank mainly made of paperboard in which a thermoplastic resin layer made of a resin having a low thermal deformation temperature of polyethylene resin is laminated on the inner surface (surface), the flange portion is heated. By using pressure, crushing to form a smooth surface with little unevenness due to squeezing wrinkles, and then heat sealing the sealing lid, the inner surface of the flange portion of the formed paper tray is made of a resin having a low thermal deformation temperature. Since it is a thermoplastic resin layer, a squeezed wrinkle generated in the flange portion during heat sealing is crushed, and a gap between the irregularities is filled to obtain a sealed paper tray container having a flange portion capable of high sealing performance. be able to.
[0028]
Therefore, in this method for manufacturing a sealed paper tray container, in the conventional paper tray molding method, in order to improve the sealing performance of the paper tray container, the temperature of the mold is increased to smooth the flange portion. Molding was difficult because the thermoplastic resin layer was in close contact with the mold. In that respect, in the manufacturing method of the sealed paper tray container of the present invention, the sealing wrinkle gap generated in the flange portion is filled when the post-processed sealing lid is heat-sealed to improve the sealing performance. The temperature of the mold on the inner surface of the paper tray is lowered so as not to adhere to the mold.
[0029]
Since this highly sealable seal can be made, products with liquid contents can be packaged. Further, it is possible to obtain a sealed paper tray container which can cope with gas replacement and gas flash and can achieve EL (extended life).
[Brief description of the drawings]
FIG. 1 is a perspective view showing a sealed paper tray container of the present invention.
FIG. 2 is a plan view showing a blank before forming the paper tray of the sealed paper tray container of the present invention.
FIG. 3 is a schematic cross-sectional view showing a molding machine for molding a paper tray in the method for producing a sealed paper tray container of the present invention.
FIG. 4 is a partial sectional view of a flange portion of the sealed paper tray container of the present invention.
[Explanation of symbols]
A Sealed paper tray container 1 Paper tray 2 Flange portion 3 Side surface 4 Bottom surface 5 Wrinkle 11 Blank 12 Flange portion region 13 Side surface region 14 Bottom surface region 15 Ruled line 16 Paper layer 17 Thermoplastic resin layer 20 Seal lid 30 Molding machine 31 Upper press head 32 Upper heater panel 33 Upper mold frame 34 Upper mold 35 Lower press head 36 Lower heater panel 37 Lower mold frame 38 Lower mold

Claims (2)

The polyethylene resin layer of the laminated body consisting of three layers of a polyethylene resin layer consisting of a low density polyethylene resin or a medium density polyethylene resin, and an outermost layer made of paper, polypropylene, polyethylene terephthalate or methylpentene polymer. A method of manufacturing a sealed paper tray container comprising a paper tray having a flange portion formed on the side, and a seal lid heat-sealed to the flange portion, the flange portion at a corner of a polygonal corner, becomes the area or the side area, a plurality of push ruffled from an outer peripheral end toward the center of the circular arc, the temperature of the female mold for molding the tray in the range of 150 to 200 ° C., male The temperature of the polyethylene resin layer is molded at a temperature lower than the heat deformation temperature (JIS K-7207) of the resin by 10 ° C. or more, A method for producing a sealed paper tray container, wherein after the contents are filled, the sealing lid is heat-sealed. A paper tray having a flange portion molded with the polyethylene resin layer of the laminate consisting of a single layer of a low density polyethylene resin or a medium density polyethylene resin and a two-layer paper blank as the inner surface side; and A method for manufacturing a sealed paper tray container comprising a seal lid that is heat-sealed to a flange portion, wherein the region that becomes the flange portion or the side surface of the corner portion of the polygonal corner has a circular arc from the outer peripheral end. A plurality of creases are provided toward the center, the temperature of the female mold of the mold for forming the paper tray is set in the range of 150 to 200 ° C., and the temperature of the male mold is the thermal deformation temperature of the resin of the polyethylene resin layer ( A method for producing a sealed paper tray container, wherein the sealing lid is heat-sealed after being molded at a temperature 10 ° C. or more lower than JIS K-7207) and filled with contents.

Images