METHOD FOR MANUFACTURING FOOD PACKAGING PAPER TRAY THAT CAN BE EASILY SEPARATED AND DISCARDED

Abstract

According to a method for manufacturing a food packaging paper tray that can be easily separated and discarded, the paper tray is manufactured with paper of a predetermined thickness, and the bottom surface, wall surfaces and outward flange of the paper tray are coated (attached) with the synthetic resin oriented film, and thus the firm exterior shape thereof is maintained, and sealing and packaging thereof are possible by means of the sealing and packaging machine using thermoplastic films through the outward flange to which the synthetic resin oriented film is attached. Particularly, the synthetic resin oriented film is adhered, while stretched, to the bottom surface, wall surfaces and outward flange of the paper tray through an adhesive applied to the lower surface thereof, so as to ensure the waterproof function of the paper tray, and can be easily separated from the paper tray if pulled by applying artificial power.

Claims

1. A method of manufacturing a paper tray for food packaging that is easy to be separated and discarded, in which food products can be sealed and packaged through a sealing machine using a thermoplastic film, the method comprises: a blanking step of cutting out a paper tray in a shape of an unfolded diagram from a base paper of a predetermined thickness, the unfolded diagram having a quadrilateral bottom surface serving as a bottom, four wall surfaces extending from each side of the quadrilateral bottom, each of the four wall surfaces being foldable through partial cut-and-fold lines at each side of the bottom surface to serve as a wall, and an outward flange being foldable outwardly through a half-cutting line at the top of the wall surfaces to serve as an attachment portion for the thermoplastic film; a step of forming a paper tray in which a paper tray is formed by placing the paper tray in the shape of the unfolded diagram made in the above blanking step on a base mold, the base mold having a tray-receiving part having a bottom and wall surfaces identical to the outer shape of the paper tray from the blanking step with an open top, and by pressing the bottom surface downwardly such that the four wall surfaces are folded upwardly at each side of the bottom surface, while folding the outward flanges horizontally from the top of the wall surfaces toward the outside to form a body shape of the paper tray; a step of attaching a stretch film in which a sheet of synthetic resin stretch film treated with a mordant (removable adhesive) on its back surface facing the tray is placed to cover the top of the paper tray received in the tray-receiving part of the base mold and then the sheet of synthetic resin stretch film is press-attached onto the upper surface of the outward flanges of the paper tray through a film attachment mold, while cutting the sheet of the synthetic resin stretch film along the edge of the outward flanges; a step of coating the tray with a stretch film in which, while the outward flanges are pressed and fixed on the upper surface of the base mold through the film attachment mold after the stretch film attachment step, the central part of the synthetic resin stretch film covering the opening top of the paper tray is pressed down through a film coating-plug mold made identical to the internal shape of the paper tray to stretch the synthetic resin stretch film and attach the film on the bottom and wall surfaces of the paper tray; and a step of ejecting and stacking the paper tray coated with the synthetic resin stretch film from the base mold after the stretch film coating step.

2. The method of claim 1, characterized in that the film attachment mold and the film coating-plug mold are preheated to 100-140 C. to apply heat to the synthetic resin stretch film in the steps of attaching and coating a stretch film.

3. The method of claim 1, characterized in that, in the stretch film coating step, the internal air of the paper tray and the base mold is forcibly discharged by a vacuum pump so that the synthetic resin stretch film easily attaches to the bottom surface and wall surface of the paper tray.

4. The method of claim 3, characterized in that an air pressure is applied downwardly to the synthetic resin stretch film so that the synthetic resin stretch film attaches easily to the bottom and wall surfaces of the paper tray in the stretch film coating step while the film is stretched.

5. The method of claim 1, characterized in that the sheet of the synthetic resin stretch film is preheated to 140-180 C. by a heater in the stretch film attachment step.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 is a perspective view of a paper tray for food packaging that is easy to be separated and disposed of according to the present invention.

[0017] FIG. 2 is a cross-sectional view along lines II-II of FIG. 1, showing a cross-sectional structure of a paper tray for food packaging according to the present invention.

[0018] FIG. 3 is an unfolded diagram of a paper tray for food packaging according to the present invention.

[0019] FIG. 4 is a process block diagram sequentially illustrating a method of manufacturing a paper tray for food packaging according to the present invention.

[0020] FIG. 5 is a schematic illustration of a paper tray forming step in a paper tray manufacturing method according to the present invention.

[0021] FIG. 6 is a schematic illustration of a step of attaching a stretch film in a paper tray manufacturing method according to the present invention.

[0022] FIG. 7 is a schematic illustration of a preheating process of the synthetic resin stretched film used in the present invention.

[0023] FIG. 8 is a schematic illustration of a stretch film coating step in a paper tray manufacturing method according to the present invention.

[0024] FIG. 9 is a schematic illustration of an ejection step in a paper tray manufacturing method according to the present invention.

[0025] FIG. 10 is a schematic illustration of a paper tray according to the present invention with a portion of the stretch film removed for disposal after use.

TABLE-US-00001 Description of the numerals 100. paper tray 110. bottom surface 111. partial cut-and-fold line 120. wall surface 121. half-cutting line 130. outward flange 200. stretch film 210. heater 300. mordant 400. base mold 410. tray receiving part 500. film attachment mold 600. film coating-plug mold 700. vacuum pump 800. air compressor S10. Blanking step S20. Paper tray- forming step S30. Stretch film attachment step S40. Stretch film coating step S50. Ejection step

EMBODIMENTS

[0026] Hereinafter, preferred embodiments according to the present invention is described in detail with reference to the accompanying drawings.

<Detailed Description of the Elements of a Paper Tray for Food Packaging According to the Present Invention>

[0027] Referring to FIGS. 1 and 2, a paper tray 100 for food packaging according to the present invention is for sealing and packaging food such as various side dishes, food, delivery food, and the like through a sealing packaging device using a thermoplastic sealing sheet (sealing film); it is made of paper and has a bottom surface, four wall surfaces 120, and an outward flange 130, and is open at the top. The inner surface of such paper tray 100 is coated (attached) with a synthetic resin stretch film 200 to maintain the shape of the paper tray 100 while securing a waterproof function.

[0028] Again, a paper tray 100 for food packaging according to the present invention comprises a quadrilateral bottom surface 110 serving as a bottom, four wall surfaces 120 each configured to be folded inclined upwardly through partial cut-and-fold lines 111 at each side of the bottom surface 110 to serve as walls, and an outwardly facing flange 130 configured to be folded outwardly through a half-cutting line 121 at the top of the four wall surfaces 120 to serve as an adhesive portion of the thermoplastic film. This paper tray 100 is made by tearing an unfolded form of the paper tray from a sheet of paper and folding via Thompson processing to provide a bottom surface 110, four wall surfaces 120, and an outwardly facing flange 130, as shown in FIG. 3. The four wall surfaces 120 are partially cut at the four sides of the bottom surface 110 via partial cut-and-fold lines 111, but also are partially connected, in order to facilitate upright folding without being separated from the bottom surface 110.

[0029] Furthermore, the bottom surface 110 and the inner surface of the wall surfaces 120 and the top surface of the outward flanges 130 of the paper tray 100 are coated with a synthetic resin stretch film 200, thus the paper tray 100 is waterproof and maintains its shape, and food products can be packaged and sealed in the paper tray 100 through a sealing device using a thermoplastic film (i.e., a sealing film). The paper tray 100 for food packaging according to the present invention is made by tearing off the paper tray 100 from a hygienic and eco-friendly pulp monolayer base paper in an unfolded form, and continuously feeding the tray to a paper tray molding coating device to make a paper tray 100.

<Description of a Manufacturing Method of a Paper Tray for Food Packaging According to the Present Invention>

[0030] The following describes the manufacturing method of a paper tray for food packaging according to the present invention, as described above, with reference to the accompanying drawings.

[0031] As shown in FIG. 4, the method of manufacturing a paper tray for food packaging according to the present invention comprises blanking step S10 in which a paper tray 100 is torn off from a base paper in an unfolded form so that a paper tray is constructed by folding it; a paper tray folding step S20 in which the paper tray 100 in the unfolded shape made in the blanking step (S10) is placed on a base mold 400 and pressed to form a body shape; a stretch film attachment step (S30) in which a synthetic resin stretch film (200) is attached and cut along the outward flange (130) while covering the upper part of the paper tray (100) received in the base mold (400); after the stretch film attachment step S30, a stretch film coating step S40 in which a central portion of the synthetic resin stretch film 200 covering the open area of the paper tray 100 is pressed so that the bottom surface 110 and the wall surface 120 of the paper tray 100 are coated with the film 200; and an ejection step S50 in which the paper tray 100 coated with the synthetic resin stretch film 200 is ejected from the base mold 400 and stacked.

[0032] The blanking step S10 is a process of tearing off the paper tray 100 from the base paper in an unfolded form so that the paper tray 100 is constructed by folding it, as shown in FIG. 3. The base paper used may be a single-layer pulp paper, corrugated cardboard, or the like. The paper tray 100 is torn off from such a base paper through a wood mold into a foldable form (so-called Thompson process), and in an embodiment of the present invention, the paper tray 100 has a quadrilateral bottom surface 110 that serves as a bottom, four wall surfaces 120 each foldable inclined upwardly through a partial cut-and-fold line 111 at each side of the bottom surface 110 to serve as walls, and an outwardly facing flange 130 at the top of each of the four wall surfaces 120 that is foldable outwardly through a half-cut line 121 to serve as an adhesive part for the thermoplastic film.

[0033] And the paper tray molding step S20 as shown in FIG. 5 is a process where the paper tray 100 in the form of an unfolded diagram made in the blanking step S10 is placed on the base mold 400 having a tray-receiving portion 410 with an open top, a bottom and walls identical to the external shape of the paper tray 100, and the bottom surface 110 of the tray 100 is pressed down from the top so that the four wall surfaces 120 are folded upward at each side of the bottom surface 110, and the outward flange 130 is folded horizontally from the top of the wall surface 120 toward the outside to form the body shape of the paper tray 100. In the paper tray molding step S20, the paper tray 100 in the form of an unfolded diagram is received in the tray-receiving portion 410, and the four wall surfaces 120 are folded inclined upwardly along the partial cut-and-fold line 111, and the outward flange 130 is spread by folding the outward flange 130 horizontally from the top of the four wall surfaces 120 toward outside through the half-cutting line 121.

[0034] The stretch film attachment step S30 as shown in FIG. 6 is a process where a sheet of synthetic resin stretched film 200 treated on its underside with a mordant (removable adhesive) 300 is placed to cover the top of the paper tray 100 received in the tray-receiving part 410 of the base mold 400, and then the sheet of synthetic resin stretch film 200 is cut along the edge of the outward flange 130 while the sheet of synthetic resin stretch film 200 is pressed attached onto the upper surface of the outward flange 130 of the paper tray 100 using the film attachment mold 500. As shown in FIG. 7; the synthetic resin stretch film 200 is wound in the form of a roll. It is preferable that the roll is preheated by a heater 210 to 140 to 180 C. while the roll is unwound before being fed to the stretch film attachment step S30. This is so that the synthetic resin stretch film 200 can be stretched and attached smoothly without difficulty in the stretch film coating step S40 following the stretch film attachment step S30. Furthermore, in the stretch film attachment step S30, the film attachment mold 500 is preheated to 100 to 140 C. (in one embodiment of the present invention, it is set to 120 C.) by a heater (not shown), so that the synthetic resin stretch film 200 is attached while pressed onto the outward flange 130 and while heat is applied to the synthetic resin stretch film 200. Thus, the synthetic resin stretch film 200 is easily attached to the outward flange 130 of the paper tray 100 through the mordant 300 treated on its underside.

[0035] The stretch film coating step S40 as shown in FIG. 8 is a process where, following the stretch film attachment step S30, while the outward flange 130 is pressed and fixed on the top surface of the base mold 400 through the film attachment mold 500, and the central portion of the synthetic resin stretch film 200 covering the opening of the paper tray 100 is pressed downward using film-coating plug mold 600 made identical to the internal shape of the paper tray 100 so that the bottom surface 110 and wall surfaces 120 are coated with the synthetic resin stretch film 200 while the film is stretched. In the process of performing the stretch film coating step S40, the synthetic resin stretch film 200 is preheated, so that it can be stretched smoothly without difficulty, thereby reducing the coating process time and increasing work productivity. Furthermore, in the stretch film coating step S40, the film coating-plug mold 600 is also preheated to 100 to 140 C. (in one embodiment of the present invention, it is set to 120 C.) by a heater (not shown), so that the preheated synthetic resin stretch film 200 is heated and stretched smoothly without difficulty and press-attached to the bottom surface 110 and wall surface 120 of the paper tray 100. Thus, the synthetic resin stretch film 200 is more easily attached to the bottom surface 110 and wall surface 120 of the paper tray 100 through the mordant 300 treated on its underside. In this stretch film coating step S40, the air inside the paper tray 100 and the base mold 400 is forced out through a vacuum pump 700 to ensure that the synthetic resin stretch film 200 stretches and firmly attaches to the bottom surface 110 and the wall surface 120 of the paper tray 100 without trapping any bubbles. Furthermore, in the stretch film coating step S40, the air compressor 800 is used to apply air pressure to the synthetic resin stretch film 200 downwardly from the top of the synthetic resin stretch film 200, so that the synthetic resin stretch film 200 can be easily attached to the bottom surface 110 and the wall surface 120 of the paper tray 100 as the synthetic resin stretch film 200 is stretched.

[0036] The ejection step S50 is a process in which the paper tray 100 coated with the synthetic resin stretch film 200 is automatically taken out from the base mold 400 after the stretch film coating step S40 and stacked through a pick-up means (not shown), as shown in FIG. 9.

[0037] In this way, the paper tray 100 for food packaging according to the present invention is manufactured by through a process including feeding the paper tray 100 made in the form of an unfolded diagram in the blanking step S10 to the base mold 400 and performing a paper tray forming step S20.fwdarw.a stretch film attachment step S30.fwdarw.a stretch film coating step S40.fwdarw. and an ejection step S50. The paper tray 100 for food packaging made by the manufacturing method according to the present invention has a bottom surface 110, four inclined wall surfaces 120, and an outward flange 130, and a synthetic resin stretch film 200 is coated on the top of the bottom surface 110, the inclined wall surfaces 120, and the outward flange 130 through a mordant 300 to maintain the folded shape.

[0038] In particular, the paper tray 100 for food packaging according to the present invention is made by making a frame of the tray for food packaging with paper, which is an environmentally friendly material, and coating the inner surface (upper surface) thereof with an adhesive synthetic resin stretch film 200, so that sealed packaging is possible through a sealing packaging machine in which a thermoplastic film is used while securing a waterproof function.

[0039] Furthermore, when the paper tray for food packaging according to the present invention is discarded, the synthetic resin stretch film 200 attached to the inner surface (upper surface) of the paper tray 100 can be peeled off for separate disposal, as shown in FIG. 10. In other words, the synthetic resin stretch film 200 is attached to the bottom surface 110, the wall surface 120, and the outward flange 130 of the paper tray 100 through the mordant 300, and can be easily peeled off by applying some artificial force. Therefore, the paper tray 100 for food packaging can be disposed of for recycling after the synthetic resin stretch film 200 being removed, thereby increasing recycling of the resources and reducing environmental pollution.

INDUSTRIAL APPLICABILITY

[0040] The present invention has wide applications in the field of a method for manufacturing a paper tray for food packaging that is easy to be separated and disposed of in which the tray frame (body) is made of paper, which is an environmentally friendly material, and the inner surface is coated (attached) with an adhesive synthetic resin stretch film to secure a waterproof function while enabling sealed packaging.