JP5725880B2 - Paper container and manufacturing method thereof - Google Patents

Description

  The present invention relates to a paper container and a method for producing the same, and more particularly to a paper container suitable for heating by retort sterilization, a microwave oven, a microwave oven, or the like, and a method for producing the same.

  As a paper container that can be heated by retort sterilization, a microwave oven, or the like, for example, a paper tray of Patent Document 1 is known. In this paper tray, a paper box is assembled in a tray shape via a folding line, and a thermoplastic sheet is laminated on the inner surface of the paper box. In the flange portion at the upper end of the paper tray, a winding portion is formed in which the thermoplastic sheet laminated on the inner surface extends to the back surface, and the exposed portion of the paper end surface is covered by the winding portion. Yes.

On the other hand, in the paper container of Patent Document 2, a paper tray body having a flange portion is formed by drawing a paperboard on which a thermoplastic sheet is laminated, and this paper tray body is placed in an injection mold. The thermoplastic resin is integrally formed so as to cover the flange portion.
In any of the paper containers described in the patent documents, the flange portion of the paper material is covered with a thermoplastic resin to improve rigidity, and deformation during heating is prevented.

JP 2000-255562 A JP 2000-335550 A

By the way, in the paper containers described in these patent documents, since the flanged container is formed by drawing the paper material, the peripheral portion is reduced in diameter at the time of the drawing process, so the paper materials overlap in the circumferential direction, In particular, large unevenness occurs in the thickness direction in the flange portion due to the overlapping portion. This unevenness becomes larger as it is closer to the periphery of the flange portion. Further, due to variations in the elongation of the material during the drawing process, the peripheral edge of the flange portion is not evenly formed and becomes wavy, and the width of the flange portion is likely to vary in the circumferential direction.
For this reason, when the flange portion is covered with a resin by winding a thermoplastic sheet around the flange portion as described in Patent Document 1 or by injection molding a thermoplastic resin as described in Patent Document 2, the entire flange is covered. It is necessary to form the resin with a thick wall and a wide flange. Therefore, there is a problem that the amount of the resin used for coating increases, the entire flange becomes large, and the overall weight increases.
In addition, when the paper material is deepened, there is a problem that the paper material is pulled and a molding defect occurs such that the lower portion of the peripheral wall portion is broken.

  The present invention has been made in view of the above circumstances, and is a paper container suitable for heating such as retort sterilization and a microwave oven, and ensures the rigidity of the flange portion to prevent the flange portion from being deformed. At the same time, it is an object of the present invention to provide a paper container that can be formed compactly by reducing the overall weight and that can be easily molded, and a method for manufacturing the same.

The paper container of the present invention includes a bottomed cylindrical cup portion in which a blank and a peripheral wall portion surrounding the bottom portion are integrally formed by drawing a blank made of a paper material, and continuous from the upper end portion of the cup portion. And a concave portion and a convex portion extending in the depth direction are formed over the entire circumference of the peripheral wall portion of the cup portion, and the depth of the concave portion is 50 μm to 250 μm. The flange portion includes a cylindrical portion along the peripheral wall portion of the cup portion, and an annular flat plate portion extending horizontally from the cylindrical portion, and the cylindrical portion is an upper end surface of the peripheral wall portion of the cup portion. The flange is fixed so as to overlap a part of the peripheral wall portion, and the resin of the flange portion enters the concave portion on the inner peripheral surface side and the outer peripheral surface side of the peripheral wall portion.

As described above, since the cylindrical portion of the resin flange portion is fixed to the upper end portion of the peripheral wall portion of the cup portion, it is not necessary to form a flange portion in the cup portion when the paper material is drawn. Since the cylindrical portion of the flange portion is fixed so as to overlap a part of the peripheral wall portion in a state of covering the upper end surface of the peripheral wall portion of the cup portion, a slight height is formed on the upper end surface of the peripheral wall portion of the cup portion. Even if the variation occurs, it is possible to prevent the separation between the cup portion and the flange portion by reliably connecting the flange portions with the overlapping portions of the cylindrical portions.
In addition, since the flange portion is formed of resin and the annular flat plate portion does not include a molded part of paper material, the thickness of the annular flat plate portion can be reduced and the surface thereof should be formed flat. Can be finished smoothly without undulating the periphery. Therefore, the width of the annular flat plate portion can be reduced.

  The overlapping portion of the upper end portion of the peripheral wall portion of the cup portion and the cylindrical portion of the flange portion is such that at least one side of the inner peripheral surface side of the peripheral wall portion and the cylindrical portion are covered with the upper end surface of the peripheral wall portion. Any one may be sufficient as long as it overlaps, and the cylindrical part may be arranged on the inner surface side of the peripheral wall part, or the cylindrical part may be arranged on the outer surface side of the peripheral wall part. Alternatively, the cylindrical portion may be formed over both the inner and outer surfaces of the peripheral wall portion so that the peripheral wall portion is buried in the cylindrical portion.

In this case, a concave portion extending in the depth direction is formed on at least a part of the entire circumference of the peripheral wall portion of the cup portion, and the resin of the flange portion enters the concave portion.
Even when it is formed so that at least one side of the inner peripheral surface side of the peripheral wall portion of the cup portion and the cylindrical portion of the flange portion overlap, the flange portion is fixed in a state of covering the upper end surface of the peripheral wall portion, During the injection molding of the flange portion, a part of the resin enters the concave portion from the upper end surface of the peripheral wall portion to the opposite surface side, and the resin is arranged on both the inner and outer surfaces of the peripheral wall portion by this resin. The flange portion can be firmly fixed .

The paper container manufacturing method of the present invention includes a cup portion that forms a bottomed cylindrical cup portion in which a blank and a peripheral wall portion surrounding the bottom portion are integrally formed by drawing a blank made of paper. Injecting a flange portion composed of a forming step, a cylindrical portion fixed in the upper end portion of the peripheral wall portion of the cup portion with the cup portion disposed in the mold, and an annular flat plate portion projecting horizontally from the cylindrical portion And forming a concave portion and a convex portion extending in the depth direction over the entire circumference of the peripheral wall portion of the cup portion, and the depth of the concave portion is 50 μm to 50 μm. In the flange portion forming step, the peripheral wall portion is clamped by the mold below the cavity with the upper end portion of the peripheral wall portion of the cup portion exposed in the cavity of the mold. And resin in the cavity The cylindrical portion is integrally fixed to the upper end portion of the peripheral wall portion in a state where the resin enters the concave portion on the inner peripheral surface side and the outer peripheral surface side of the peripheral wall portion.

  By this manufacturing method, the cup portion and the flange portion are formed so that the cylindrical portion overlaps the upper end portion of the peripheral wall portion in a state where the upper end surface of the peripheral wall portion is covered, and the flange portion is thinned to be compact, A paper container that can be reduced in weight can be manufactured. In this case, it is not necessary to provide a flange part when molding a cup part from a paper blank, so that it can be molded while sliding the blank into the mold during drawing, reducing the occurrence of defects and yield. Can be manufactured well.

  According to the present invention, since the resin flange portion is provided, rigidity can be secured and deformation due to heating such as retort sterilization or a microwave oven can be prevented, and since the resin alone has a flange portion, It is possible to reduce the overall weight by reducing the amount of resin used, and to form a compact. For this reason, for example, space can be saved when displaying in a store or the like, and the lid for covering the flange portion can be made small. Since the burden at the time of drawing the cup portion is small, it can be easily formed into various shapes such as a round shape, a square shape, and a bowl type, and can be applied to a wide range of uses.

BRIEF DESCRIPTION OF THE DRAWINGS The 1st Embodiment of the paper container of this invention is shown, (a) is the front view which made half the end surface, (b) is an expanded sectional view of the part applied to the flange part from the surrounding wall part. It is a top view of the paper container of FIG. It is the front view which used the half of the cup part in the paper container of FIG. 1 as the end surface. It is a top view which shows the blank before shape | molding the cup part of FIG. It is sectional drawing of the principal part which shows the state which has arrange | positioned the cup part of FIG. 3 in the injection mold. It is an arrow expanded sectional view which follows the XX line of FIG.1 (b). It is sectional drawing of the principal part which shows the state which accumulated the paper containers of FIG. It is the front view which made half the end surface which shows 2nd Embodiment of the paper containers of this invention. It is a top view of the paper container of FIG. It is a top view which shows 3rd Embodiment of the paper containers of this invention. It is a front view which used the half of the paper container of FIG. 10 as the end surface.

Embodiments of the present invention will be described below with reference to the drawings.
1 to 7 show a first embodiment of the present invention.
The paper container 1 has a bottomed cylindrical cup portion 2 and a flange portion 5 fixed to the upper end portion 3 a of the peripheral wall portion 3 of the cup portion 2.
Among these, the cup part 2 is formed by drawing the blank 6 made of the paper material shown in FIG. The blank 6 is formed in a disk shape, and a large number of ruled lines (score grooves) 7 and 8 are formed in a region where the peripheral wall portion 3 of the cup portion 2 is formed. These ruled lines 7 and 8 are formed radially around the blank 6 except for the central part of the blank 6 as a whole, and two types of long and short are formed, and the long ruled line 7 and the short ruled line 8 are circumferentially arranged. Alternatingly arranged. For example, 200 ruled lines 7 and 8 are formed at intervals of 1.8 °, and 100 long and short lines are formed. Note that the ruled lines 7 and 8 are not provided in a range of a predetermined distance (for example, about 1 mm) from the outer peripheral edge of the blank 6, and the flat portion 9 is disposed at this portion. As a paper material constituting the blank 6, for example, the thickness is about 0.2 to 0.5 mm, and a resin layer (not shown) made of a synthetic resin such as polypropylene (PP) is formed on the front and back sides of the paper material. Is formed. In addition, films made of materials with low oxygen permeability such as aluminum foil and EVOH (ethylene vinyl copolymer) resin may be laminated. By laminating these aluminum foil and EVOH resin, the contents are prevented from being oxidized. This has the effect of extending the storage period.

  The circular blank 6 is drawn by a heated mold (not shown) to form the bottomed cylindrical cup portion 2 shown in FIG. The cup portion 2 has a shape in which a circular bottom portion 11 and a peripheral wall portion 3 surrounding the circular bottom portion 11 are integrally formed. At this time, since the width and interval of the ruled lines 7 and 8 described above are narrowed in the circumferential direction by drawing, the ruled lines 7 and 8 are formed on the peripheral wall portion 3 as shown partially enlarged in FIG. Along with the recesses 14 </ b> A, the portion between the ruled lines becomes the protrusions 14 </ b> B, and a part of the peripheral wall portion 3 overlaps at the boundary to form a large number of crease portions 15. Further, the peripheral wall portion 3 is formed in a tapered shape having a diameter gradually increased toward the upper end portion 3a.

  In the cup portion 2, as described above, the flange portion 5 formed of resin is integrally fixed to the upper end portion 3a of the peripheral wall portion 3. The flange portion 5 is fixed to the cup portion 2 by injection molding, and the resin forming the flange portion 5 may be polypropylene of the same material as the resin that forms the resin layer of the paper material, but is cooked in a microwave oven or the like. When the contents to be stored are contained, PBT (polybutylene terephthalate) resin or PET (polyethylene terephthalate) resin having excellent heat resistance may be used. The thickness of the resin is, for example, about 0.5 to 1 mm.

  The flange portion 5 has a cylindrical portion 12 that is a fixed portion to the cup portion 2 and is formed along the peripheral wall portion 3, and an annular flat plate portion 13 that projects horizontally from the upper end of the cylindrical portion 12. doing. The cylindrical portion 12 is formed to be longer than the flat portion 9 of the cup portion 2, and this length is sufficient to fill the height difference of the upper edge of the upper end portion 3 a caused by distortion during drawing (for example, about 10 mm). ). In FIG. 1 and the like, the flange portion 5 is fixed so as to overlap the outer peripheral surface of the upper end portion 3a of the peripheral wall portion 3 with the cylindrical portion 12 covering the upper end surface 3b of the peripheral wall portion 3 of the cup portion 2. Integrated. In this case, the cylindrical portion 12 may be fixed to the inner peripheral surface of the upper end portion 3a in addition to the configuration fixed to the outer peripheral surface of the upper end portion 3a, or the upper end portion 3a may be fixed to both inner and outer peripheral surfaces. It is good also as a form fixed in the state which buried the upper end part 3a so that it may pinch | interpose from.

Then, the manufacturing method of the paper container 1 comprised in this way is demonstrated.
This manufacturing method can be divided into a cup part forming process in which the cup part 2 is formed by the blank 6 of paper material and a flange part forming process in which the flange part 5 is formed in the cup part 2 by insert molding by injection molding.
The cup part 2 is formed by pressing the blank 6 and drawing as described above. At this time, since the flange portion is not formed, the cup portion 2 can be smoothly formed while the blank 6 is slid into the press mold.

  In the flange portion forming step, an injection mold shown in FIG. 5 is used. The injection mold 16 is composed of a pair of mold plates 17 and 18, and when these mold plates 17 and 18 are combined, an annular cavity for forming a flange portion is formed between the mold plates 17 and 18. 19 is formed. Further, pressing contact portions 20 and 21 are formed in the lower portion of the cavity 19 so as to sandwich the inner and outer peripheral surfaces of the peripheral wall portion 3 with the upper end portion 3 a of the peripheral wall portion 3 protruding into the cavity 19. The pressing contact portions 20 and 21 are set so as to face each other with a space smaller than the thickness of the peripheral wall portion 3 of the cup portion 2 at the time of clamping, so that the peripheral wall portion 3 is held in a pressed state. Yes. Further, an escape cavity portion 22 is formed below the pressing contact portions 20 and 21 for disposing the lower portion of the cup portion 2 with a slight gap. Further, the gate 19 is connected to the cavity 19 at, for example, two 180 ° opposing positions. A runner 24 and a sprue 25 are connected to the gate 23, and an injection molding machine is connected to the sprue 25. This is a structure in which molten resin is injected from the head and injected into the cavity 19.

Then, by placing the cup portion 2 between the mold plates 17 and 18 and clamping the mold, the inner and outer peripheral surfaces of the peripheral wall portion 3 are sandwiched by the pressing contact portions 20 and 21, and the upper end portion 3a is exposed in the cavity 19. It will be in the state. In FIG. 5, the outer peripheral surface of the upper end portion 3 a faces the inside of the cavity 19 from the upper end surface 3 b of the peripheral wall portion 3. In this state, molten resin is injected and injected into the cavity 19, and the cylindrical portion 12 is fixed to the upper end portion 3 a of the peripheral wall portion 3 of the cup portion 2 to integrate the flange portion 5. At this time, the resin layer on the surface of the cup part 2 and the injected resin are welded, and the cup part 2 and the flange part 5 are firmly fixed. Further, the upper end surface 3 b of the peripheral wall portion 3 is covered with the cylindrical portion 12 of the flange portion 5.
In this case, as described above, the concave portion 14A and the convex portion 14B are formed on both surfaces of the peripheral wall portion 3, but the pressing contact portions 20 and 21 sandwich the peripheral wall portion 3 at an interval smaller than the thickness of the peripheral wall portion 3. Therefore, the unevenness of the peripheral wall portion 3 is crushed and the injected resin is reliably prevented from protruding downward beyond the pressing contact portions 20, 21. Regarding the peripheral wall portion 3, the thicknesses of the portion sandwiched by the press contact portions 20 and 21 after the injection molding and the unloaded portion below the portion (the portion disposed in the cavity portion 22 at the time of mold clamping) are measured. As a result, the portion sandwiched between the pressing contact portions 20 and 21 was 320 μm to 353 μm (average 337 μm), and the lower unloaded portion was 333 μm to 465 μm (average 374 μm). The measurement was performed using a dial thickness gauge manufactured by Teclock Co., Ltd., and measuring was performed on a plurality of containers at four locations at 90 ° intervals per container.

The paper container 1 obtained in this way does not need to form a flange portion in the cup portion 2 in advance, and the flange portion 5 is formed of a single resin, thereby preventing the flange portion 5 from being distorted and the annular flat plate portion 13 from being formed. Flatness can be improved, and the overall thickness can be reduced by reducing the thickness and width of the flange portion 5.
Further, if the end surface of the paper material is exposed, paper dust may be generated from the end surface, but the upper end surface 3b of the peripheral wall portion 3 in the cup portion 2 is formed by the cylindrical portion 12 of the resin flange portion 5. Since it is covered, paper dust is not generated and it is hygienic.
Moreover, since this paper container 1 is thicker in the peripheral wall portion 3 of the cup portion 2 than the other portion, the fixing portion of the cylindrical portion 12 of the flange portion 5 is, as shown in FIG. When the paper containers 1 are stacked, a gap G is generated between the annular flat plate portions 13 of the flange portion 5 by the cylindrical portion 12, so that the paper containers 1 can be easily separated even when stored in a stacked state. .

As shown in FIG. 5, the mold clamping structure is such that the cylindrical portion 12 is formed on the outer peripheral surface side of the peripheral wall portion 3, but as described above, the concave portion 14A and the convex portion 14B are deep on both surfaces of the peripheral wall portion 3. Since it is formed along the vertical direction, even if the inner peripheral surface of the peripheral wall portion 3 is held in contact with the template plate 17, the recess 14 </ b> A causes the gap between the template plate 17 and the inner peripheral surface of the peripheral wall portion 3. A gap is formed. Therefore, when the resin is injected into the cavity 19, a part of the resin also enters the recess 14A on the inner peripheral surface side of the peripheral wall 3 from the upper end surface 3a of the peripheral wall 3, and as a result, as indicated by P in FIG. A resin layer is partially or thinly formed on the inner peripheral surface side of the peripheral wall portion 3 over the entire circumference, and the cylindrical portion 12 is formed integrally with the outer peripheral side resin.
Incidentally, when the cross section of the peripheral wall 3 was photographed with a digital microscope VHX-200 / 100F manufactured by Keyence Corporation, and the depth D of the recess 14A was measured using the function in the measuring instrument, it was 50 μm to 250 μm. Met.

8 and 9 show a second embodiment of the paper container of the present invention. In the paper container 31 of this embodiment, a rectangular bowl-shaped cup portion 32 is formed by drawing, and a flange portion 35 is integrally fixed to the upper end portion 33a of the peripheral wall portion 33 of the cup portion 32 by injection molding. It is. Also in this case, the flange portion 35 includes a rectangular tubular portion 36 that is fixed so as to overlap the upper end portion 33 a while covering the upper end surface 33 b of the peripheral wall portion 33 of the cup portion 32, and the upper end of the tubular portion 36. It is comprised from the cyclic | annular flat plate part 37 protruding horizontally from.
Even in such a square bowl-shaped paper container 31, since the flange portion is not formed when the cup portion 32 made of paper is drawn, the drawing from the blank is facilitated and the occurrence of defects is reduced. be able to. Then, the rectangular annular flat plate portion 37 can be formed flat and thin with a small width by the resin flange portion 35, and the size and weight can be reduced.
In the case of this square cup portion 32, the blank material is formed with ruled lines only at the portions corresponding to the four corners of the square, and the concave portions 14A and the convex portions 14B caused by the ruled lines at the time of drawing are formed at the four corners of the square. Arise. Therefore, at the time of injection molding of the flange portion 35, when one side of the peripheral wall portion 33 is held in contact with the mold plate, the resin mainly enters between the mold plate and the peripheral wall portion 33 at the four corners so that the front and back surfaces are integrated. To be molded.

10 and 11 show a third embodiment of the paper container of the present invention. In the paper container 41 of this embodiment, a relatively oval relatively shallow cup portion 42 is formed by drawing, and the flange portion 45 is integrally fixed to the upper end portion 43a of the peripheral wall portion 43 of the cup portion 42 by injection molding. It is a thing. Also in this case, the flange portion 45 has a cylindrical portion 46 that is fixed so as to overlap the upper end portion 43a in a state of covering the upper end surface 43b of the peripheral wall portion 43 of the cup portion 42, and a horizontal portion from the upper end of the cylindrical portion 46. It is comprised from the cyclic | annular flat plate part 47 which protrudes.
In the case of the paper container 41, as in the case of the above-described embodiments, the flange portion is not formed at the time of drawing the cup portion 42 made of paper material. The annular flat plate portion 47 can be formed flat and thin with a small width by the resin flange portion 45, and the size and weight can be reduced.
Also in the elliptical cup portion 42, the peripheral wall portion 43 is formed with a concave portion 14A and a convex portion 14B, although there is a difference in density between a portion having a small curvature radius and a portion having a large curvature radius, and the flange portion 45 is formed. Is formed on the front and back of the peripheral wall 43.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, the cup portion may have a shape other than the above-described embodiments, and may be provided in various shapes such as a shallow square dish shape. Further, in the embodiment of the manufacturing method, the gate part at the time of injection molding is formed at two places, but it may be formed at three places at intervals of 120 °, and from the back surface of the annular flat plate part by a submarine gate. It is good also as a structure to inject | pour. Furthermore, a known injection molding technique such as a runnerless mold can be applied.
Further, in order to ensure ultrasonic welding of the lid member, a protruding strip bead having a triangular cross section may be provided along the circumferential direction on the upper surface of the annular flat plate portion of the flange portion. Also in that case, since the annular flat plate portion itself can be formed thin, even if a bead is provided, the overall thickness can be kept small.

DESCRIPTION OF SYMBOLS 1 Paper container 2 Cup part 3 Peripheral wall part 3a Upper end part 3b Upper end surface 5 Flange part 6 Blank 11 Bottom part 12 Cylindrical part 13 Annular flat plate part 14A Concave part 14B Convex part 15 Fold part 16 Mold 17, 18 Template 19 Cavity 20 Press contact portion 31, 41 Paper container 32, 42 Cup portion 33, 43 Peripheral wall portion 33a, 43a Upper end portion 33b, 43b Upper end surface 35, 45 Flange portion 36, 46 Cylindrical portion 37, 47 Annular flat plate portion

Claims (2)

A bottomed cylindrical cup portion in which a blank and a peripheral wall portion surrounding the bottom portion are integrally formed by drawing a blank made of paper, and a resin flange portion continuous from the upper end portion of the cup portion. A concave portion and a convex portion extending in the depth direction are formed over the entire circumference of the peripheral wall portion of the cup portion, and the depth of the concave portion is 50 μm to 250 μm, and the flange portion is The peripheral wall portion includes a cylindrical portion along the peripheral wall portion of the cup portion and an annular flat plate portion extending horizontally from the cylindrical portion, and the cylindrical portion covers an upper end surface of the peripheral wall portion of the cup portion. The paper container is characterized in that it is fixed so as to overlap with a part of the resin, and the resin of the flange portion enters the concave portion on the inner peripheral surface side and the outer peripheral surface side of the peripheral wall portion. A cup part forming step for forming a bottomed cylindrical cup part in which a blank and a peripheral wall part surrounding the bottom part are integrally formed by drawing a blank made of paper material, and the cup part is disposed in a mold And a flange portion forming step of injection molding a flange portion comprising a cylindrical portion fixed to the upper end portion of the peripheral wall portion of the cup portion and an annular flat plate portion extending horizontally from the cylindrical portion. In the part forming step, a concave portion and a convex portion extending in the depth direction are formed over the entire circumference of the peripheral wall portion of the cup portion, and the depth of the concave portion is formed to be 50 μm to 250 μm. The upper end portion of the peripheral wall portion of the cup portion is exposed in the cavity of the mold, the peripheral wall portion is sandwiched by the mold below the cavity, and the resin is injected into the cavity to inject the peripheral wall At the upper end of the A method for manufacturing a paper container, wherein the cylindrical portion is fixed integrally with the resin in the concave portion on the inner peripheral surface side and the outer peripheral surface side of the wall portion.

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