A paper fresh-keeping box

Abstract

The invention discloses a paper fresh-keeping box, comprising a box body formed by cutting and folding a whole sheet of cardboard, a film layer covered on the inner surface of the box body by a blister process, and the cardboard comprises a bottom wall which is an overall square structure and serves as the bottom surface of the box body, left and right side walls connected to the left and right edges of the bottom wall, and front and rear side walls connected to the front and rear edges of the bottom wall, and the left and right side walls, the front and rear side walls and the bottom wall are all provided with crease lines at their junctions; the left and right edges of the front and rear side walls are reserved with sheet parts superimposed on the front and rear edges of the left and right side walls, and the upper edge of the box body is also folded together by the outer edges of the left and right side walls and the front and rear side walls to form a flange, and the sheet parts are superimposed on the left and right side walls and are mutually pressed or bonded by glue or by ultrasonic bonding. Its technical solution makes the production process simpler, the sealing effect is better, the strength is better, and the shelf life can be effectively improved and extended.

Description

Technical Field

[0001] The present invention relates to the technical field of paper lunch boxes, and in particular to a paper fresh-keeping box. Background Art

[0002] With the development of economy and the acceleration of the pace of life, lunch boxes are widely used in daily life, mainly including take-out packaging and use as fresh-keeping utensils in supermarket refrigerators. At present, lunch boxes are mainly divided into lunch boxes made of plastic lunch boxes and lunch boxes made of paper materials.

[0003] As for fresh-keeping boxes made of plastic materials, due to their one-piece molding and material characteristics, they can ensure their own sealing and the flatness of the upper edge of the periphery, and then after covering the cover film, they can ensure the sealing of the packaged food. However, due to the non-renewable and high pollution of the material, they do not conform to the concept of sustainable development promoted today, and are gradually being phased out. Therefore, paper fresh-keeping lunch boxes are beginning to replace plastic fresh-keeping lunch boxes on the market.

[0004] At present, paper lunch boxes are mainly made by splicing or bonding one or more sheets of coated paper to form a square or round box body, and adhering a film layer inside the box body. After placing the food in the box body, a cover film is adhered to form a fresh-keeping box. In theory, since the edges of the coated paper are spliced ​​together, there is no transition gap, and the thickness of the spliced ​​position is the same. After the film layer is adhered, there is no overlapping part and the thickness of each position is maintained. In the process of adhering the cover film, the cover film and the film layer fit each other without a theoretical gap, thereby ensuring sealing.

[0005] At the same time, in order to meet the requirements of sealing, the edges of the coated paper are generally directly aligned, and then the connection at the aligned position is achieved by adhering a film layer. However, it is obvious that the side walls of the box body themselves have a tendency to expand outward, especially after the food is placed or the food is too heavy, the film layer will be subjected to a large expansion force in both directions at the aligned seam position. The film layer is always kept in a fatigue state of tension, which can easily damage the film, especially after being placed for a long time, resulting in visible or invisible gaps at the seams, thereby reducing the sealing. When stored for a long time, bacteria can easily invade the interior of the lunch box and destroy the freshness of the food. Summary of the invention

[0006] In view of the above problems existing in the prior art, a paper fresh-keeping box with a simple production process and good sealing effect is provided to overcome the above technical defects.

[0007] The specific technical solutions are as follows:

[0008] A paper fresh-keeping box, comprising a box body formed by cutting and folding a whole sheet of cardboard, and a film layer covered on the inner surface of the box body by a blister process, wherein the cardboard comprises a bottom wall which is in a square structure as a whole and serves as the bottom surface of the box body, left and right side walls connected to the left and right edges of the bottom wall, and front and rear side walls connected to the front and rear edges of the bottom wall, and crease lines are formed at the junctions of the left and right side walls, the front and rear side walls and the bottom wall;

[0009] The left and right edges of the front and rear side walls are reserved with sheet parts that are overlapped on the front and rear edges of the left and right side walls. The upper edge of the box body is also folded together by the outer edges of the left and right side walls and the front and rear side walls to form a flange. After the sheet parts are overlapped on the left and right side walls, they are pressed together or bonded by glue or ultrasonic bonding.

[0010] Preferably, the outer edge of the flange is further folded downward to form a skirt.

[0011] Preferably, the periphery of the film layer is bonded to the flange, and the paper fresh-keeping box further comprises a cover film, and the periphery of the cover film is bonded to the periphery upper surface of the film layer.

[0012] Preferably, the inner wall of the box body is folded twice by the left and right side walls and the front and rear side walls to form an annular stepped surface with an "L"-shaped cross section.

[0013] Preferably, the lower edge of the sheet portion is in an angled shape matching the shape of the front and rear edges of the left and right side walls.

[0014] Preferably, the sheet portion overlaps the inner surfaces of the left and right side walls.

[0015] Preferably, the cover film is bonded to the film layer as a whole, and food and inert gas are stored in the storage space enclosed by the film layer and the cover film.

[0016] Preferably, the outer edge of the flange is further turned downward and curled to form a curled edge.

[0017] Preferably, in the longitudinal section direction, the curling edge is spiral-shaped as a whole.

[0018] The beneficial effects of the above technical solution are:

[0019] The paper fresh-keeping box includes a box body and a film layer. The box body includes a bottom wall, front and rear side walls, left and right side walls, and a flange. The left and right edges of the front and rear side walls are reserved with sheet parts overlapped on the left and right side walls. The box body is formed by cutting and folding a whole piece of cardboard. The film layer is covered on the inner surface of the box body through the blister forming process, which makes the overall production process simpler and the sealing effect is better. The strength of the four corners of the box body is better. When in use, the food is placed in the box body and then covered with a layer of cover film to complete the fresh-keeping packaging of the food. The sealing is good and can effectively improve and extend the shelf life. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1It is a three-dimensional diagram of the paper fresh-keeping box of the present invention;

[0021] Figure 2 This is a three-dimensional diagram of the paper fresh-keeping box of the present invention from another perspective;

[0022] Figure 3 It is a top view of the paper fresh-keeping box of the present invention;

[0023] Figure 4 This is a planar development diagram of the paper fresh-keeping box of the present invention;

[0024] Figure 5 for Figure 2 A partial enlarged view of the middle I part;

[0025] Figure 6 It is a cross-sectional view of the overlapping position of the sheet material parts on the flange of the paper fresh-keeping box of the present invention;

[0026] Figure 7 It is a partial cross-sectional structural schematic diagram of another embodiment of the paper fresh-keeping box of the present invention. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is specifically described in the following embodiments in conjunction with the accompanying drawings.

[0028] Embodiment 1

[0029] See also Figures 1 to 6 As shown in Figure 3 The direction perpendicular to the paper plane outward is the direction from bottom to top in this embodiment, then Figure 3 The left-right direction in the figure is the left-right direction in this embodiment, and the top-to-bottom direction is the back-to-front direction in this embodiment.

[0030] The paper fresh-keeping box provided in this embodiment includes a box body 1 formed by cutting and folding a whole piece of cardboard, a film layer 10 covered on the inner surface of the box body 1 by a blister process, and the cardboard includes a bottom wall 2 which is an overall square structure and serves as the bottom surface of the box body 1, left and right side walls 3 connected to the left and right edges of the bottom wall 2, and front and rear side walls 4 connected to the front and rear edges of the bottom wall 2. The left and right side walls 3, the front and rear side walls 4 and the bottom wall 2 all have crease lines 9 at their junctions, and the left and right edges of the front and rear side walls 4 are reserved with sheet portions 5 overlapped on the front and rear edges of the left and right side walls 3. The upper edge of the box body 1 is also folded together by the outer edges of the left and right side walls 3 and the front and rear side walls 4 to form a flange 6. After the sheet portion 5 is overlapped on the left and right side walls 3, they are pressed together or bonded by glue or ultrasonically.

[0031] Based on the above technical scheme, the paper fresh-keeping box includes a box body 1 and a film layer 10. The box body 1 includes a bottom wall 2, front and rear side walls 4, left and right side walls 3, and a flange 6. The left and right edges of the front and rear side walls 4 are reserved with sheet parts 5 overlapped on the left and right side walls 3, and the box body 1 is formed by cutting and folding a whole piece of cardboard. The film layer 10 is covered on the inner surface of the box body 1 through the blister forming process, which makes the overall production process simpler and the sealing effect is better. The strength of the four corners of the box body 1 is better, and it is not easy to be damaged during transportation due to the excessive weight of the food contained. When in use, the food is placed in the box body 1 and then covered with a layer of cover film to complete the fresh-keeping packaging of the food. The sealing is good and can effectively improve and extend the shelf life.

[0032] In a preferred embodiment, the outer edge of the flange 6 is further folded downward to form a skirt 7, which, on the one hand, further enhances the strength of the box body 1, and on the other hand, facilitates tearing off the cover film in subsequent use to open the fresh-keeping space between the cover film and the film layer 10. Further, the periphery of the film layer 10 is bonded to the flange 6, and the paper fresh-keeping box further includes a cover film 11, and the periphery of the cover film 11 is bonded to the upper surface of the periphery of the film layer 10. Further, the cover film 11 is also bonded to the skirt 7.

[0033] In specific use, such as Figure 6 As shown in Figure 6 In order to clearly show the following description, the relative thickness is exaggerated. Theoretically, compared with the prior art, since the flange of the present invention is formed by overlapping two pieces of cardboard at the joint position, although the overlapping position has the thickness of two pieces of cardboard through mutual pressing or gluing or ultrasonic bonding, especially at the edge of the sheet portion 5, a step structure is inevitably formed (such as Figure 6 The seam of the middle B part) causes wrinkles to be formed at this position after the film layer 10 is covered (such as Figure 6 In the further operation of adhering the cover film, after the cover film and the film layer 10 are attached to each other, there may be a problem of poor sealing at the fold position.

[0034] However, in actual production, the thickness of the cardboard is generally 0.5mm, and the maximum thickness of the step B formed by the overlapped sheet parts is only 0.5mm. In the process of using a mold to press the box body, since the cardboard itself is a compressible material, the step B can be kept within 0.01mm due to compression. At the same time, under the premise that the thickness of the film layer 10 and the cover film 11 is thin enough (for example, the thickness of the conventional film is 0.03mm), the above-mentioned wrinkles can be relatively negligible, especially the operation of covering the film is generally also carried out on the equipment, which is achieved by pressing and heating and melting. The film layer 10 and the cover film 11 can be bonded together in theory, and the problem of the two not being able to be completely sealed due to the wrinkle problem can be completely solved. At the same time, the step B can be further compressed during the pressing process. In addition, the specific production test results of this scheme show that it can indeed ensure that the sealing of the wrinkle position meets the standard requirements, and the film can be prevented from being damaged in the long-term storage state as faced by the prior art.

[0035] In addition, the above-mentioned blister process mainly includes:

[0036] Step a, placing the box body 1 formed by cutting and assembling the cardboard in the blister mold on the blister station, the film roll is stretched as a sheet and arranged above the box body 1, and the film roll is heated and softened by a heating component located above the film roll; preferably, the lower surface of the film roll has glue, or glue is applied on the flange 6 of the box body 1, so that the viscosity is better in the heated state.

[0037] Step b, a vacuum device arranged in the vacuum forming station performs vacuum forming operation on the film roll through a gap existing in the cardboard itself but invisible to the naked eye (the gap can also be formed by directly opening a vacuum hole on the bottom wall to enhance the vacuum forming ability), and the film roll is pressed downwardly against the box body 1 under the action of the vacuum device to form a film layer 10; and the suction port of the vacuum device can be arranged at any position outside the box body 1;

[0038] Step c, further performing heat pressing or ultrasonic bonding operation on the peripheral edge of the film bonded to the edge.

[0039] In a preferred embodiment, the inner side wall of the box body 1 is further folded twice by the left and right side walls 3 and the front and rear side walls 4 to form an annular stepped surface 8 with an "L"-shaped cross section, so that the overall structure of the box body 1 is more stable. Further, the lower edge of the sheet portion 5 is in an angled shape that matches the shape of the front and rear edges of the left and right side walls 3. Specifically, the entire cardboard is cut into Figure 4The shape is shown, and the fold line 9 around the bottom wall 2 is an indentation, and the left and right side walls 3 and the front and rear side walls 4 are cut at their junctions, that is, the sheet portion 5 is formed by cutting. Furthermore, the sheet portion 5 is overlapped on the inner surfaces of the left and right side walls. And the thickness of the overlapping portion is the thickness of two pieces of cardboard. Compared with the existing method of directly placing the edges of the cardboard opposite each other and gluing the edges through the adhesive film layer 10, the sealing is better, and since the thickness of the cardboard itself is relatively small, the thickness of the two pieces of cardboard does not affect its normal use. Furthermore, the film layer 10 and the cover film 11 are both made of EVOH material and have a high barrier effect. And in specific use, the storage space surrounded by the film layer 10 and the cover film is used to store food and inert gas (preferably nitrogen), which can effectively extend the shelf life of the food.

[0040] Specifically, during the operation of bonding the cover film, the equipment simultaneously places the food in the storage space and replaces the gas in the storage space with nitrogen. On the one hand, a sealed food storage space is formed between the film layer and the cover film, and on the other hand, ordinary air is replaced by inert gas, so that the food is isolated from oxygen, effectively extending its shelf life.

[0041] Embodiment 2:

[0042] Combination Figure 7 As described in, the content and structure of the paper fresh-keeping box provided in this embodiment are basically the same as those in the above embodiment, and the only difference is that in this embodiment, the outer edge of the flange 6 is further turned down and curled to form a curling edge 12, so that the strength of the edge of the box body can be greatly enhanced, and the problem of the side concave caused by the packaging cover film 11 and the process of evacuating and replacing gas during specific use can be avoided. Furthermore, in the longitudinal section direction, the curling edge 12 is spiral as a whole, but obviously, the degree of spirality of the curling edge 12 can be changed according to the overall size of the box body, and can be curled only once, or can be curled multiple times to form a curling edge 12. Figure 7 This configuration can effectively prevent the situation where multiple boxes cannot be separated due to airtightness problems when they are overlapped and packed, making it more convenient to use.

[0043] The above description is only a preferred embodiment of the present invention, which is only illustrative and not restrictive of the present invention. Those skilled in the art understand that many changes, modifications, and even equivalences may be made to the present invention within the spirit and scope defined by the claims of the present invention, but all of them will fall within the scope of protection of the present invention.

Claims

1. A paper fresh-keeping box, characterized in that: The box body (1) is formed by cutting and folding a whole sheet of cardboard, and a film layer (10) is covered on the inner surface of the box body (1) by a blister process. The cardboard includes a bottom wall (2) which is in a square structure as a whole and serves as the bottom surface of the box body (1), left and right side walls (3) connected to the left and right edges of the bottom wall (2), and front and rear side walls (4) connected to the front and rear edges of the bottom wall (2). The left and right side walls (3) and the front and rear side walls (4) are all provided with crease lines (9) at the junctions with the bottom wall (2). The left and right edges of the front and rear side walls (4) are reserved with a sheet portion (5) for being overlapped with the front and rear edges of the left and right side walls (3); the upper edge of the box body (1) is also folded together by the outer edges of the left and right side walls (3) and the front and rear side walls (4) to form a flange (6); after the sheet portion (5) is overlapped with the left and right side walls (3), they are pressed together or bonded by glue or ultrasonic bonding; the periphery of the film layer (10) is bonded to the flange (6); the paper fresh-keeping box also includes a cover film (11), and the periphery of the cover film (11) is bonded to the upper surface of the periphery of the film layer (10); The lower edge of the sheet portion (5) is in an angled shape matching the shape of the front and rear edges of the left and right side walls (3); two adjacent sheet portions (5) overlap; the thickness of the sheet portion (5) is smaller than the flange (6); and the connection position between the sheet portion (5) and the flange (6) is a transition section with a continuously changing thickness.

2. The paper fresh-keeping box according to claim 1, characterized in that: The outer edge of the flange (6) is further folded downward to form a skirt (7).

3. The paper fresh-keeping box according to claim 1 or 2, characterized in that: The inner side wall of the box body (1) is also folded twice by the left and right side walls (3) and the front and rear side walls (4) to form an annular stepped surface (8) with an "L"-shaped cross section.

4. The paper fresh-keeping box according to claim 1, characterized in that: The sheet portion (5) is overlapped on the inner surfaces of the left and right side walls (3).

5. The paper fresh-keeping box according to claim 1, characterized in that: The cover film (11) is bonded to the film layer (10) to form a whole, and food and inert gas are stored in a storage space surrounded by the film layer (10) and the cover film (11).

6. The paper fresh-keeping box according to claim 1, characterized in that: The outer edge of the flange (6) is further turned over and curled downward to form a curling edge (12).

7. The paper fresh-keeping box according to claim 6, characterized in that: In the longitudinal section direction, the curling edge (12) is spiral-shaped as a whole.

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