JPH04308724A - Molded body with flange part and its manufacture - Google Patents

Abstract

PURPOSE:To make it pussible to tear easily a vessel by hand, by a method wherein at the time of manufacturing of a vessel for a round rice-cake by molding a raw fabric sheet made of plastic having a linear low-strength part, the low-strength part is provided almost in parallel with an orientating direction of resin of the raw fabric sheet. CONSTITUTION:A packed round rice-cake 1 is constituted of a vessel body part 3 and bottom sheet 4, the vessel body part 3 is obtained by performing vacuum molding or air-pressure forming of a sheetlike matter made of plastic into a form of a round rice-cake having a constricted part at the vicinities of the center and lower end and a flange 5 is formed on the lower end part. A bottom sheet 4 also is comprised of a sheet made of plastic, heat-sealed on the lower end of the vessel body part 3 and seals up tightly the vessel body part 3. In the case of manufacturing of a vessel for the round rice-cake like this, a linear low-strength part (thin part) 6 is formed on the surface of a form part of the round rice-cake of the vessel body part 3 in almost parallel with an orientating direction of the sheet made of the plastic. Then a notched part 7 is provided on a position where the fringe part of the flange 5 and thin part 6 are crossed and a leading part 8 is formed on the upper part of the notched part 7.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a molded article with a flange formed by vacuum forming or air pressure forming, and a method for manufacturing the same, and particularly to a molded object made by vacuum forming or air pressure forming which can be easily torn by hand and has excellent strength. The present invention relates to a molded article with a flange portion and a method for manufacturing the same.

0002

BACKGROUND OF THE INVENTION Conventionally, molded bodies with flanges formed by vacuum forming or pressure forming plastic sheets have been widely used as containers for various foods, confectionery, and the like.

[0003] A molded article with a flange formed by vacuum forming or pressure forming such a plastic sheet is as follows:
An example is a container for wrapped kagami mochi.

[0004] The packaged kagami-mochi 1, as shown in FIG. 8, is a kagami-mochi container body 3 made of plastic filled with kagami-mochi 2.

The container body 3 is formed by vacuum forming a plastic sheet into the shape of a kagami-mochi (rice cake) with an open bottom.After this is inverted and filled with the rice cake 2, the bottom is sealed with a plastic sealing sheet (bottom sheet). ) 4 and then heat treated. Polypropylene or the like is used for such a container body 3 from the viewpoints of strength, water resistance, sealability, heat sealability, and the like. Moreover, the polypropylene used is of considerable thickness and hardness in order to ensure shape retention and gas barrier properties. Further, as the bottom sheet 4, a heat-sealable plastic such as polyethylene is used.

In this packaged kagami mochi, the mochi 2 is removed from the container body 3.
To take out the rice cake, the rice cake 2 is usually cut along with the container body 3 using a knife or the like, and after the cutting, the container body 3 and the rice cake 2 are separated. This is because the container body 3 and the rice cake 2 are in close contact with each other, and it is not easy to remove the rice cake just by peeling off the bottom sheet 4. However, when cutting the mochi 2 together with the container body 3 using a knife or the like, since the container body 3 has a certain degree of hardness and wall thickness as described above, a large pressing force is first applied with the knife or the like. Moreover, since the outer surface of the container body 3 is smooth, there is a problem that the knife tends to slip easily and cause injury.

[0007] Thus, vacuum-formed containers are difficult to open. Therefore, a container has been proposed that can be easily torn by hand from the flange by forming low-strength parts such as linear thin-walled parts and cuts in the original fabric sheet and then performing vacuum forming or pressure forming. There is.

[0008] However, as a result of subsequent research, when attempting to tear by hand a container obtained by vacuum forming or pressure forming after providing a linear low-strength portion in the original fabric sheet, in some cases It turns out that it is not always easy to tear apart. If it could be torn more easily by hand, it would be advantageous because it would be able to meet the recent trend of pursuing simplicity.

[0009] Accordingly, an object of the present invention is to provide a molded article with a flange portion formed by vacuum forming or pressure forming, which can be easily torn by hand and has excellent strength.

Another object of the present invention is to provide a method for manufacturing the above-mentioned molded article with a flange portion.

[0011]

[Means for Solving the Problems] In view of the above problems, as a result of intensive research, the present inventors have provided a linear low-strength portion in a plastic sheet, and have developed a molding method that can be obtained by vacuum forming or pressure forming the linear low-strength portion. As a result of various studies on the ease of tearing the package, we found that it is closely related to the orientation direction of the original plastic sheet, and that if a linear low-strength part is provided almost parallel to this orientation direction, it will be easier to open the package. They discovered that it is possible to do this, and came up with the present invention.

That is, in the molded article with a flange portion of the present invention, which is obtained by vacuum forming or pressure forming a raw plastic sheet having a linear low-strength portion, the linear low-strength portion is formed from the raw plastic sheet. It is characterized in that it is provided substantially parallel to the orientation direction of the resin, and is easily torn along the linear low-strength portion.

The method of the present invention for producing the above-mentioned molded article with a flange portion includes providing a linear low-strength portion approximately parallel to the orientation direction of the resin of the original plastic sheet, and performing vacuum forming or pressure forming. , which is characterized by forming a linear low-strength portion that is easily tearable.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings. 1 and 2 are a front view and a plan view of a wrapped kagami mochi, which is a typical example of the molded article with a flange portion of the present invention.

[0015] The packaged rice cake 1 is made by filling a container body 3 with the rice cake 2 and then heat-sealing the bottom sheet 4. Container body part 3
This is a plastic sheet-like material that is vacuum-formed or pressure-formed into a kagami-mochi shape with constrictions near the center and lower end, and a flange 5 is formed at the lower end.

The bottom sheet 4 is also made of plastic and is heat-sealed to the flange 5 to seal the container body 3 (not shown in FIG. 2). The bottom sheet 4 is made of a material that is easy to peel from the container body 3, so that the sealing sheet (bottom sheet) 4 can be easily peeled off from the container body 3 when taking out the rice cake 2. It is set as.

In such a kagami-mochi container, the container body 3
On the surface of the kagami-mochi-shaped portion, a linear low-strength portion (thin wall portion) 6 is formed substantially parallel to the orientation direction of the plastic sheet (indicated by an arrow in the figure, the same applies hereinafter). A notch 7 is provided at the intersection of the edge of the flange 5 and the linear thin wall portion 6, and a guide portion 8 is formed above the notch 7. In this example, the low-strength portion 6 is a thin walled portion, but it does not need to be thin as long as it can be easily torn when the notch is grasped and torn by hand. However, the strength may be reduced by thermal denaturation or chemical denaturation.

[0018] The guide part 8 prevents the ease of opening of the seal from decreasing because the linear thin wall part provided on the original fabric sheet during the production of the flanged molded article tends to shift, albeit slightly, from the notch. It shall be provided as appropriate for the purpose of doing so.

FIG. 3 shows an enlarged view of the notch 7, guide portion 8, and their surrounding areas in such a kagami-mochi container. In FIG. 3, the guiding portion 8 is a substantially V-shaped cutout 81, 8.
2, 83, and these cutouts are arranged in a triangular shape (cutout 81 is the apex, cutout 82,
83 as another point). It is preferable that the V-shaped cutouts 82, 83 have a somewhat acute angle, for example, about 60° as in this embodiment. Preferably, the V-shaped cutout 81 has an angle about twice that of the cutouts 82 and 83 described above, and the legs of the V shape extend slightly above the tops of the cutouts 82 and 83.

[0020] In the present invention, the substantially V-shape does not necessarily have a sharp tip as in this embodiment, but may have a slightly rounded tip, or a shape with two concave curves. Also includes those formed by convex curves. In addition, since the guiding part only needs to be weak to some extent in terms of strength, it does not need to be a cutout like in this example, but rather a thin part (including a groove).
But that's fine. However, in terms of ease of opening, it is preferable that the strength is lower than that of the linear low-strength part (thin-walled part 6) provided in the container body.

Further, the guide portion 8 does not have to be V-shaped and arranged in a triangle, but may be arranged in a rhombus, trapezoid, or the like. Furthermore, when arranged in a triangle, the number of pieces does not need to be three as in this example, but six pieces (V
There may be three additional cutouts below the letter-shaped cutouts 82, 83) or any other number.

[0022] In such a container, the linear thin wall portion provided on the original fabric sheet during its manufacture tends to shift, albeit slightly. Some aspects of this shift are illustrated in FIGS. 4 to 6. In any of the cases shown in FIGS. 4 to 6, the linear thin part 6
intersects with the V-shaped cutout at multiple locations. For this reason, the strength of this part is significantly reduced, and when you start tearing, the cutout 82 (or cutout 83)
) and then to the top of the next cutout 81, and the thin part is reached from the top of the cutout 81. In some cases, it may be necessary to reach the thin wall part from the top of the cutout 82, or even reach the thin wall part of the cutout 82.
(or the cutout 83) may be torn directly along the thin wall portion 6.

[0023] When tearing like this, the way it breaks is uncertain depending on the direction and amount of force, etc. However, when the guide part is made of a substantially V-shaped cutout as in the present invention, the trajectory of the tear line travels from the point where the tear begins, via the cutout, to the thin wall part easily and quickly, and then It progresses smoothly along the thin part. In this way, it becomes possible to easily remove the contents of the container.

Moreover, since the flange-equipped molded article of the present invention leaves the filled portion intact, it is also excellent in strength.

There are no particular limitations on the plastic sheet forming the molded article with flanges of the present invention, and single plastics or laminates of plastics can be used. As a single plastic, polypropylene is preferable, and as a laminate, a layered structure such as polypropylene/polyvinyl alcohol/polypropylene is preferable. In addition, when using a kagami mochi container as in this example, higher fatty acids such as stearic acid can be added to the plastic resin for the purpose of improving the peelability from the mochi. If the above-mentioned sheet-like material is made of a simple plastic, a higher fatty acid may be added to the plastic, and if the sheet-like material is a laminated sheet, stearic acid, etc. may be added to the resin of the innermost layer (the surface in contact with the rice cake). You can add higher fatty acids. When adding higher fatty acids such as stearic acid, the amount added is preferably 0.1 to 5% by weight.

[0026] The thickness of the sheet may be appropriately set depending on the intended use of the molded article; for example, in the case of a container, it may be appropriately set depending on the article to be filled, size, shape, weight, etc. When using a kagami-mochi container as in this embodiment, the weight of the mochi filled in the kagami-mochi container body 3 is usually 160 g to 8 kg.
It is preferable to use one with a diameter of about 550 μm to 1.5 mm. Sheet thickness is 550μ
If it is less than m, it will be difficult to maintain the kagami-mochi shape when filling the mochi, and it will also be difficult to have gas barrier properties.
Further, if the thickness exceeds 1.5 mm, vacuum forming or pressure forming becomes difficult.

However, in the present invention, the sheet needs to be oriented to some extent. For this purpose, the sheet only needs to be slightly stretched. The stretching ratio may be approximately 2 times or less, and may be much smaller than the 4 to 7 times that is the stretching ratio of uniaxial or biaxial stretching in normal sheet forming. In addition, if the stretching ratio is too large, heating during vacuum forming or pressure forming, which will be described later, may cause
This is not preferred because the sheet tends to shrink. In the above case, heat treatment may be performed for the purpose of preventing shrinkage of the sheet.

[0028] In order to obtain the above-mentioned stretching ratio,
The tension speed of the take-up roll and the amount of sheet extrusion may be appropriately controlled. Ordinary uniaxial or biaxial stretching may also be performed. In the case of biaxial stretching, either sequential biaxial stretching or simultaneous biaxial stretching may be used, but it is preferable that there is a certain degree of difference between the stretching ratios in the two axial directions.

A method for manufacturing the flanged molded article of the present invention using the above-mentioned sheet will be explained below.

First, a linear low-strength portion is provided on the sheet described above. In the present invention, the linear low-strength portion must be provided substantially parallel to the orientation direction of the sheet as described above. It should be noted that the low-strength portions do not need to be provided over the entire length of the sheet, and may be provided as appropriate depending on the desired location where it is desired to impart easy-opening properties to the molded article with flanges.

[0031] Such low-strength portions can usually be formed by providing cuts or grooves in the sheet. If the low-strength portion is a cut, it may be provided by laser machining, a rotary blade, or the like. In the case of grooves, they may be provided using a rotary blade or the like. Note that when laser processing is performed, strength reduction due to thermal denaturation progresses as well as thinning, so even if the degree of wall thinning is small, sufficient strength reduction can be obtained.

[0032] Examples of the laser for the laser processing include a carbon dioxide laser, an argon ion laser, a YAG laser, etc., but a carbon dioxide laser is preferable in terms of output and the like. In order to form such a cut using a laser, a laser beam may be used to scan a desired position on the plastic sheet. Note that scanning may be performed by moving the laser head while keeping the sheet fixed, or by moving the sheet conversely. The incision made by such laser processing is formed in a linear shape by a series of fine point-like recesses. This is because the output of the laser beam changes periodically, and the connection state of the recesses differs depending on the moving speed of the sheet. The recesses 40 do not need to be completely connected, and may be intermittent as long as they are close to each other.

Further, the laser output, beam diameter, and scanning speed may be appropriately set depending on the material and thickness of the plastic bottom sheet, the depth of the cut, etc. However, as for the scanning speed, the higher the scanning speed, the larger the distance between the dotted recesses becomes, which impairs the ease of opening.

[0034] The width of the low strength part as described above is 50 to 15
It is 0 μm. In the case of laser incision, the depth is 50% or less, preferably 35% of the thickness of the sheet material.
It is as follows. In addition, when making a cut by laser processing, the lower limit of the depth may be as small as scratching the surface.
In particular, it is preferably 10% or less of the thickness. For example, if the thickness of the sheet-like material is 550 μm, the depth of the cut should be 50 to 50 μm.
The thickness of the sheet-like material is preferably about 150 μm.
For 5 mm, the cutting depth is 150 to 500
The thickness is preferably about μm. Moreover, the above-mentioned cuts may be formed on one side or both sides. When forming on both sides, the depth of each cut is preferably about 25% or less of the thickness of the sheet-like material 3.

Next, the sheet having the linear low-strength portion formed in this manner is subjected to vacuum forming or pressure forming. The vacuum forming and pressure forming methods may be any commonly used methods. For example, in the case of vacuum forming, a sheet-like material may be heated and softened using a heater or the like, and pressed against a female mold by suction from the female mold side, applying pressure if necessary, so as to form the desired shape. In the case of air pressure molding, the sheet-like material may be heated and softened using a heater or the like, and pressure may be applied from the male mold side using air or the like to press it against a female mold to form the desired shape. In addition, when providing a thin-walled portion on the outer surface of the container, the incision may be made on the side that contacts the female mold.

[0036] Molding conditions vary depending on the type of plastic used, but in the case of vacuum forming, the heating temperature of the sheet is 150 to 180°C, and the degree of vacuum is 600 to 650°C.
It is preferable to set it to mmHg. In the case of air pressure forming, the sheet may be heated at a temperature of 150 to 180° C. and a pressure sufficient to deform the sheet may be applied.

[0037] The strength of the linear low-strength portion is further reduced because the sheet-like material is thinned by stretching by vacuum forming or pressure forming. In particular, when a low-strength part is made into a cut, the part that is stretched by vacuum forming or pressure forming a sheet-like object (in this example, the part that becomes a kagami-mochi shape)
Then, the cut widens, and a thin walled portion 6 as shown in FIG. 7 is formed. Furthermore, when a groove is provided in the sheet, the groove expands to some extent in the stretched portion. The depth (a) of the grooves in such thin-walled parts is usually determined by the sheet material 3 after vacuum forming or pressure forming.
It becomes 10 to 30% of the thickness (b) of 0.

[0038] After forming the kagami-mochi shape in this way, a notch and a guiding part can be provided for the purpose of further facilitating opening. The notch portion and the guide portion may be formed at the same time as cutting out the container. Note that whether the guide portion is a cutout or a thin wall portion can be freely changed by appropriately setting the pressing force of the cutter. Furthermore, the sealing sheet described later may be easily peeled off by further processing such as slightly cutting off the corner portions of the sheet or creating creases in the corner portions of the sheet. Even if this kind of processing is done at the same time as cutting out the container,
This may be followed by another step.

[0039] Such a molded article with a flange portion of the present invention usually has a sealing sheet for sealing the bottom (opening). As the sealing sheet, various plastics can be used in the same manner as the sheet for the container body described above, but in particular, single-layer materials such as polypropylene and polyethylene, and laminates of these materials with polyester, aluminum foil, etc. are used. is preferable. Its thickness is preferably 70 to 100 μm. The size and shape of the sealing sheet may be such that it can completely cover at least the opening at the bottom of the container, but it is preferably approximately the same size as the sheet-like material.

[0040] Packaging can be accomplished by heat-sealing such a sealing sheet to the bottom of the container body after the contents (rice cakes in this example) have been filled.

Such a molded article with a flange portion of the present invention can be obtained by, for example, first peeling off the sealing sheet from the container body, then holding both sides of the notch 7 by hand and pulling it to form a V-shaped cutout from the notch 7. The rice cake 2 can be taken out by tearing the container body along the thin-walled portion 6 via 8.

Although the present invention has been described above with reference to a kagami-mochi container as a typical example thereof, the present invention is not limited thereto, and the present invention can also be applied to a sheet having a low-strength portion substantially parallel to the orientation of the resin. By forming the material into various shapes by vacuum forming or pressure forming, it is possible to make moldings for various uses. In addition, the low-strength part is not limited to a thin-walled part, but may be a linear line of parts that are inferior in strength to both sides.For example, the low-strength part is not limited to a thin-walled part. The layer structure can be varied to form a linear low-strength portion having a desired strength.

Furthermore, the shape of the bottom of the kagami-mochi container does not have to be square, and can be of various shapes such as rectangular or diamond-shaped.

The present invention will be explained in more detail by the following specific examples. Example 1 Polypropylene was extruded from an extruder having a T-die and wound up with a take-up roll to produce a polypropylene sheet oriented in the flow direction and having a thickness of 0.55 mm. This polypropylene sheet was manufactured. This sheet was processed using a carbon dioxide laser processing machine (manufactured by Seidensha Electronics Co., Ltd., LA).
SUC-4000) was used to perform laser processing with an output of 25 W, and a cut with a depth of 70 μm was made approximately in the center of the sheet.
A sheet for the body of a kagami-mochi container was manufactured.

[0045] This container body sheet was placed on a frame having a kagami-mochi-shaped female mold so that the outer surface was notched, and vacuum-formed at a heater temperature of 180°C and a reduced pressure of 650 mmHg. The cut in the sheet after molding was a linear thin section with a depth of about 80 μm. After forming the kagami-mochi shape in this way, it is shaped as shown in Figures 1 and 2 (a square with a side length of 300 mm, with a notch approximately in the center of one side and three V-shaped cutouts). , with one corner cut off at an angle of approximately 45°) to produce a kagami-mochi container body.

Next, 550 g of mochi was placed in the body of the obtained kagami mochi container.
After cooling, the bottom of the kagami-mochi container body was heat-sealed with a laminated sheet (thickness: 80 μm) of polyester and nylon.

When the bottom sheet of this packaged kagami-mochi was peeled off from the corner and torn by hand from the notch, it was found that the package could be easily opened from the notch through a V-shaped cutout and along the thin linear part. did it.

Comparative Example 1 A kagami-mochi container body was manufactured in the same manner as in Example 1 except that the direction in which the low-strength portion was formed by laser processing was set perpendicular to the flow of the sheet.

Next, 550 g of mochi was placed in the body of the obtained kagami mochi container.
After cooling, the bottom of the kagami-mochi container body was heat-sealed with a laminated sheet (thickness: 80 μm) of polyester and nylon.

When the bottom sheet of this packaged kagami-mochi was peeled off from the corner and torn by hand from the notch, there were some spots along the linear thin wall where it was difficult to tear.

[0051]

Effects of the Invention As described in detail above, the molded article with a flange portion of the present invention has a linear low-strength portion substantially parallel to the orientation direction of the resin of the original plastic sheet, and this is formed by vacuum forming or compressed air. It becomes molded. Such a molded article with a flange portion of the present invention can be easily torn by hand along the low-strength portion.

[0052] Such a molded article with a flange portion of the present invention is suitable for packaging items that require easy opening and strength, such as kagami mochi containers and the like.

[Brief explanation of the drawing]

FIG. 1 is a front view of a kagami mochi container according to an embodiment of the present invention.

FIG. 2 is a plan view of a kagami mochi container according to an embodiment of the present invention.

FIG. 3 is a partially enlarged view showing the vicinity of a notch and a guide portion of a kagami mochi container according to an embodiment of the present invention.

FIG. 4 is a partially enlarged view schematically showing an example of how the linear thin portion is displaced near the notch.

FIG. 5 is a partially enlarged view schematically showing another example of how the linear thin portion is displaced near the notch.

FIG. 6 is a partially enlarged view schematically showing still another example of how the linear thin portion shifts near the notch.

FIG. 7 is a schematic diagram showing the state of a thin portion of the sheet.

FIG. 8 is a longitudinal cross-sectional view showing a state in which the kagami mochi container is filled with mochi.

[Explanation of symbols]

1...wrapped kagami mochi 2...Mochi 3... Container body 4...Bottom sheet 5...Flange part 6...Low strength part (thin wall part) 7... Notch 8...Guiding part

Claims (6)

[Claims] 1. A molded article with a flange formed by vacuum forming or pressure forming a raw plastic sheet having a linear low-strength portion, wherein the linear low-strength portion is formed from the raw plastic sheet. 1. A molded article with a flange portion, which is provided substantially parallel to the orientation direction of the resin, and is easily torn along the linear low-strength portion. 2. The molded article with a flange portion according to claim 1, wherein the linear low-strength portion of the molded article with a flange portion formed by vacuum forming or pressure forming is a thin wall portion. Molded body with. 3. The molded article with a flange portion according to claim 1, wherein at least one end of the linear low-strength portion of the molded article with a flange portion is a notch provided at an edge of the flange portion. What is claimed is: 1. A molded article with a flange portion, further comprising a guiding portion formed of a plurality of substantially V-shaped cutouts or thin-walled portions around the notch portion. 4. The molded article with a flange portion according to claim 1, wherein the molded article with a flange portion is provided with a plastic sealing sheet for sealing an opening of the container. A molded body with a flange part. 5. The molded article with a flange portion according to claim 1, wherein the plastic sheet of the container is a single layer of polypropylene or a laminate of polypropylene/polyvinyl alcohol/polypropylene. A molded body with a flange portion characterized by: [Claim 6] A linear low-strength portion is provided almost parallel to the orientation direction of the resin of the original plastic sheet, and the easily tearable linear low-strength portion is formed by vacuum forming or pressure forming. A method for manufacturing a molded body with a flange portion, characterized in that: