JP4580505B2 - 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 a thermoplastic resin layer made of a heat-resistant resin is laminated on the inner surface (surface) to form a flange portion. In the molding process where a blank made mainly of paperboard with a heat-bonding layer made of a heat-meltable resin in the region is used as a deep-drawn paper tray, the flange portion is crushed using low temperature and pressure. A sealed paper tray container having a flange portion capable of forming a smooth surface with few irregularities and heat-sealing a sealing lid later on the flange portion of the paper tray and a method for manufacturing the same It is intended to do.
[0006]
[Means for Solving the Problems]
The present invention has been studied to solve the above-described problems, and as a result, the thermoplastic resin of the blank mainly comprising a paperboard on which a thermoplastic resin layer of any one of polypropylene, polyethylene terephthalate, and methylpentene polymer is laminated on the surface. A method of manufacturing a sealed paper tray container comprising a paper tray having a flange portion formed with the layer on the inner surface side, and a seal lid that is heat-sealed to the flange portion, wherein the portion of the blank that becomes the flange A thermal adhesive layer is provided in advance on the surface, and a plurality of ruled lines are provided from the outer peripheral end toward the center of the arc in the region serving as the flange portion or the side surface of the corner of the polygon corner, and the paper tray the temperature of the female mold for molding the range of 150 to 200 ° C., to divide a portion and another portion in contact with the flange portion of the male, the flange Molding is performed by setting the temperature of the portion in contact with the heat-bonding layer to a temperature that is 10 ° C. or more lower than the thermal deformation temperature (JIS K-7207) of the heat-bonding layer, and setting the temperature of the other portion to a temperature that does not melt the thermoplastic resin layer on the surface. Then, after filling the contents, a method for producing a sealed paper tray container characterized by heat-sealing the sealing lid was found and completed.
[0008]
According to the present invention, the main material is a paperboard in which a thermoplastic resin layer made of a heat-resistant resin is laminated on the inner surface (surface), and a heat-adhesive layer made of a heat-meltable resin is previously provided in a region to be a flange portion. In the molding process of making the blank to be deep-drawn paper tray, the flange part is crushed by using low temperature and pressure to form a smooth surface with few irregularities, and later in the paper tray flange part, By heat-sealing the sealing lid, the inner surface of the flange portion of the molded paper tray is a heat-bonding layer made of a resin having a high heat deformation temperature, so that the wrinkle generated in the flange portion during heat sealing is crushed, It is possible to obtain a sealed paper tray container having a flange portion in which a gap between the concaves and convexes is filled and can be sealed with high sealing performance.
[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 has a paperboard having a heat-resistant thermoplastic adhesive layer such as polypropylene resin laminated on the inner surface (surface) and a heat-melting heat-adhesive layer in the region 12 to be the flange portion 2 as a main material. The blank 11 to be manufactured is manufactured by press molding. 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. Further, in the region 12 (halftone dot portion) that becomes the flange portion 2, a heat-melting resin is partially applied in advance to provide a heat bonding layer.
[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 needs to have a function of protecting the contents, in particular, a function that does not leak even when a liquid substance is added, and a function such as moldability and heat resistance. 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 inner surface by extrusion or lamination.
[0014]
In addition, the heat-meltable resin used for the heat-bonding layer provided in the region 12 to be the flange portion 2 in the blank 11 is a resin such as cellulose, polyvinyl acetate, polyacryl, polyolefin, polyester, or rubber. is there. As a solvent-type, emulsion-type, or hot-melt-type coating agent containing these resins as main components, it is partially applied by a method such as gravure coating, spray coating (using a nozzle), or screen printing. The thickness of the heat bonding layer is preferably in the range of 10 to 60 μm.
[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, similar to the thermoplastic resin layer on the inner surface. As thickness, the range of 15-60 micrometers is preferable. These thermoplastic resins are formed on the outer surface by extrusion or lamination.
[0017]
The specific material structure as a whole is, for example, from the inner surface side, PP / paper, PET / paper, TPX / paper, PP / paper / PP, PET / paper / PET, TPX / paper / TPX, PP / PE. / Paper / polyethylene (hereinafter abbreviated as PE) / PP, PET / PE / paper / PE / PET, TPX / 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]
A method for manufacturing a sealed paper tray container A having a flange portion 2 that can be sealed with a 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 11 to the wrinkled portion in advance. The processing of the stamped rule 11 can be performed simultaneously with the punching process.
In this blank 11, a heat-meltable resin is partially applied in advance to a region 12 (halftone dot portion) that becomes the flange portion 2 to form a thermal adhesive layer.
[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 of the lower mold 38 is set to be 10 ° C. or more lower than the thermal deformation temperature (JIS K-7207) of the resin of the thermal adhesive layer provided on the flange portion 2 of the paper tray 1 for forming the paper tray 1. The temperature of the lower heater panel 36 is set. 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, in the lower mold 38 of the molding machine 30 for manufacturing the sealed paper tray container A of the present invention, the flange portion 2 of the paper tray 1 and the other portion are divided so that the temperature of the mold of the flange portion 2 is increased. Is a temperature that is at least 10 ° C. lower than the thermal deformation temperature of the resin of the thermal adhesive layer provided on the flange portion 2 of the paper tray 1, and the temperature of the mold in the other part is such that the heat-resistant thermoplastic resin layer is not melted. High temperature can be set. By this, the moldability of parts other than the flange part 2 can be improved.
[0023]
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.
[0024]
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 in a state after the seal lid 20 is heat sealed, the heat adhesive layer on the surface of the flange portion 2 is made of a resin having a low heat deformation temperature. By sealing the seal lid 20 after heat storage, the surface of the generated wrinkle portion is melted by heat and crushed by pressure, as shown in FIG. As a result, the liquid is not permeated and the surface irregularities are reduced. Therefore, a heat-sealing paper tray container can be obtained by heat-sealing the sealing lid 20.
[0025]
【Example】
An example of the sealed paper tray container manufactured by the method for manufacturing a sealed paper tray container of the present invention was prepared under the following conditions.
[0026]
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) PP 20 μm / paper 280 g / m ²
Resin for thermal bonding layer; DX-907 (mainly ethylene vinyl acetate copolymer) manufactured by Dainippon Ink & Chemicals, Inc.
As shown in FIG. 2, the temperature of the upper mold is used as a molding machine condition by using a blank 11 in which a thermal adhesive layer 18 is partially applied to the region 12 to be the flange portion 2 by a melt gravure coating method. Was set at 180 ° C., and the temperature of the lower mold was set at 80 ° C. to produce a paper tray having the above specifications.
[0027]
Conditions for heat sealing processing Heating temperature; 150 ° C
Pressurizing force: 350 kgf
Hold time: 0.2 seconds Seal lid specification material configuration: PET 12 μm / PP 50 μm / heat sealant (hot melt agent) 25 g / m ²
Next, after the paper tray having the flange portion was filled with the contents containing the liquid, the seal lid was sealed with heat sealing at the flange portion of the paper tray under the above conditions. As a result, it was possible to produce a highly sealed product that does not leak liquid.
[0028]
【The invention's effect】
According to the present invention, the main material is a paperboard in which a thermoplastic resin layer made of a heat-resistant resin is laminated on the inner surface (surface), and a heat-adhesive layer made of a heat-meltable resin is previously provided in a region to be a flange portion. In the molding process of making the blank to be deep-drawn paper tray, the flange part is crushed by using low temperature and pressure to form a smooth surface with few irregularities, and later in the paper tray flange part, By heat-sealing the sealing lid, the inner surface of the flange portion of the molded paper tray is a heat-bonding layer made of a resin having a high heat deformation temperature, so that the wrinkle generated in the flange portion during heat sealing is crushed, It is possible to obtain a sealed paper tray container having a flange portion in which a gap between the concaves and convexes is filled and can be sealed with high sealing performance.
[0029]
That is, in the manufacturing method of the sealed paper tray container of the present invention, the sealing wrinkle generated in the flange portion when the post-processed sealing lid is heat-sealed is filled to improve the sealing performance. The temperature of the mold at least at the flange portion on the inner surface of the paper tray is lowered so as not to adhere to the mold.
[0030]
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 paper tray blank 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 18 Thermal bonding 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 (1)

A paper tray having a flange portion formed with the thermoplastic resin layer of the blank made mainly of a paperboard on which the thermoplastic resin layer of any one of polypropylene, polyethylene terephthalate, and methylpentene polymer is laminated on the inner surface side; A method for producing a sealed paper tray container comprising a sealing lid heat-sealed to the flange portion, wherein a thermal adhesive layer is provided in advance on the surface of the flange portion of the blank, and the corners of the polygonal corners are provided. In the region that becomes the flange portion or the region that becomes the side surface, a plurality of creases are provided from the outer peripheral end toward the center of the arc, and the temperature of the female die for forming the paper tray is in the range of 150 to 200 ° C. and then, divides the portion and another portion in contact with the flange portion of the male, the heat distortion temperature of the heat-bonding layer the temperature of the portion in contact with the flange portion (JI K-7207) is set to a temperature that is 10 ° C. or more lower, the temperature of the other part is set to a temperature that does not melt the thermoplastic resin layer on the surface, and after filling the contents, the seal lid is heat sealed. A method for producing a sealed paper tray container characterized by the above.

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