JPH01167073A - Hermetically sealed container and its manufacturing - Google Patents

Abstract

PURPOSE:To obtain a throwaway hermetically sealed container which can hermetically pack the contents repeatedly and of which the lid can be reused after the open, by forming it from multi-layer sheet material having at least two layers of a surface layer and another layer laminated with adhesive on the surface layer. CONSTITUTION:This container 10 is formed of two layers of synthetic resin sheets 12a, 12b which are mutually stuck with an adhesive when a tab 22 is pulled in the direction of the arrow A, the inner sheet 12a outside perforates 13 in the periphery 12 is bartially peeled off at an adhesive layer (c) and pulled together with a top film 20 and cut off along the perforates 13 because the adhesive strength of the inner sheet 12a with a lid 21 is greater than that of the inner sheet with the sheet 12b. The sheet 12a adheres to the unsealed top film 20 and on the peeled surfaces of the sheets 12a, 12b, the adhesive remains. When the top film is pressed again, the container can be sealed by the adhesive.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a sealed packaging container suitably used for food packaging, etc., and a method for manufacturing the same. The present invention relates to a sealed packaging container that can be resealed and a method for manufacturing the same.

[Prior art] Conventionally, a plastic container is filled with an article such as jelly,
When covering the opening with a top film, a method is known in which the top film is made of the same type of plastic material as the container, and the top film is fixed to the peripheral edge of the container by heat welding. The welding surface of the heat-welded part varies depending on the welding temperature and pressure, but generally it has a considerable welding force (about 3 kg/25 mm width), and it is difficult to peel it off by pinching it with your fingers, and it is difficult to remove it with a knife. I had to use a knife to cut open the lid. In addition, if the adhesion is weakened in order to make opening easier, there is a risk that the sealing will be incomplete or that the sealed packaged product may be accidentally opened during storage or transportation.

In order to solve this problem, a method is known in which a layer coated with one type of wax (melt layer) is provided on the top film and this top film is heat-welded to the edge of the container (
(referred to as the hot melt method). This method utilizes the difference between the adhesive force and cohesive force of the melt layer, and the top film is peeled off by cohesive failure of the melt layer, thereby making it easier to open the top film. However, this method has the disadvantage of not being oil resistant.

Another method is to form the top film using a base material different from the base material of the container, provide an adhesive resin layer containing a vinyl acetate copolymer on the top film, and then heat weld this top film to the container. be. In this method, by appropriately selecting the heat welding pressure, sealing time, and sealing temperature, it is possible to adjust the adhesive strength to a level that allows even infants and elderly people to peel off the top film from the container with their fingers. Possible (e.g. 800g/25m+a width ~ 1.2kg)
However, the disadvantage of this method is that the welded part is sensitive to heat, and when heat treatment such as retort treatment is performed, pinholes occur during the treatment, making it impossible to use it for retort products. be.

In addition, a container having a recess and an edge around the recess is formed of a multilayer sheet having a two-layer structure, and one layer of the multilayer sheet on the upper surface of the edge of the container is attached along the boundary area between the recess and the edge. Also known are containers in which slits are made in the ti of a multilayer sheet. This container is fixed with a sheet-like top film to form a sealed container. The top film has a lid portion and a tab portion extending from the lid portion, and the tab portion is not attached to the edge surface and is designed to be pulled away from the edge of the container when opening the sealed container. When pulled, one layer of the multilayer sheet at the outer edge of the cut portion of the container will stick to the lid and the other layers will peel off to the cut, and one layer of the multilayer sheet with the cut will peel along the cut. The top film is then separated from the container, and the sealed packaging container is opened. This method is based on the adhesive strength between sheets in a multilayer sheet (for example, 500 to 1000 g
/25mm width) and the adhesive force between the container and the top film (for example, 3kg).

These sealed packaging containers are increasingly in demand as disposable containers for various foods, sanitary products, and other products due to the increase in small households, especially single-person households, and demands for rationalization of life.

However, consumers of sealed packaged products do not necessarily consume all of a bag of packaged products at once.

- Once opened, the lid cannot be reused to store the remaining packaged product.

Therefore, if the packaged product is a sanitary product such as a portable disinfectant cotton or a disinfectant towel, or if it is a food product that does not like dryness or, conversely, a food product that does not like moisture, it must be packaged for -doses. For example, today there are products for single people that are packed with food such as pickled plums, but this increases packaging costs and is undesirable from the perspective of resource conservation. It is troublesome to transfer and store it in another container.

Therefore, although there has been a need for inexpensive sealed packaging containers with reusable top films to preserve leftover packaged goods, to the best of the inventor's knowledge there are no disposable packaging containers that satisfy such requirements. Sealed packaging containers are not provided.

[Problem to be solved by the invention]

An object of the present invention is to provide a disposable sealed packaging container with a top film that allows products for multiple uses to be hermetically packaged and the lid to be reused for multiple openings and closings after opening, and a method for manufacturing the same. .

Another object of the present invention is to provide a sealed packaging container that can be tightly sealed during packaging before use or when displaying the packaged product, and can be easily opened when unsealed, and a method for manufacturing the same.

[Means to solve the problem]

That is, the present invention is formed from a multilayer sheet material having at least two layers: a surface layer and a layer laminated to the surface layer via an adhesive, and has the surface layer as the innermost layer, and a recess and a layer around the recess. a container having a flat edge, a cut in the innermost layer on the upper surface of the edge along a boundary area between the recess and the edge; The present invention provides a sealed packaging container characterized by comprising a lid portion firmly fixed to the lid portion and a top film having a tab portion extending from the lid portion and not secured to the edge surface. be.

In the present invention, the multilayer sheet material that is the material of the container has a surface layer and at least two layers in contact with the surface layer (preferably a two-layer sheet made of synthetic resin), and these two layers are made of an adhesive. are laminated through. In other respects, the multilayer sheet technology used for forming known containers is similarly applicable to the multilayer sheet of the present invention.

The adhesive used in the present invention is not particularly limited, and includes rubber-based,
Acrylic, vinyl, silicone, and other adhesives can be used.

The container has a recess and a flat edge along the periphery thereof, and a notch is made in the upper surface of the edge of the container along the boundary area between the recess and the edge. This incision may be formed as a closed figure along the boundary area over the entire circumference of the recess, or may be formed as an open figure with only a portion remaining. The part that is not cut serves as a hinge for the lid, and when the packaging container is opened and the remaining product is to be stored, it can be easily sealed by simply closing the lid again.

Conventionally, multilayer sheets bonded together using adhesives have been known, but during molding, air bubbles occur in the adhesive layer, resulting in extremely poor-looking molded products, and such sheets are difficult to mold into containers. Not used for processing. In the present invention,
It is preferable to quickly volatilize the solvent in the adhesive and perform molding using a multilayer sheet laminated through an adhesive with no residual solvent.This allows molding without creating bubbles in the adhesive layer. can do. This two-layer sheet laminated with an adhesive interposed therebetween can be produced by a known method such as applying an adhesive to the sheet and laminating it, or coextruding the two-layer sheet together with an adhesive.

The innermost layer of the multilayer sheet outside the cut at the edge of the container can then be easily peeled off from the layer in contact with it, and the innermost layer outside the cut and the top film are firmly attached. Therefore, satisfactory sealing is obtained, and when the top film is opened, the innermost layer and the layer in contact with it are peeled off, and then at the cut, the inner layer is separated along with the top film along the cut, making opening easier. Furthermore, since the adhesive remains on the peeling surface between the innermost layer and the layer in contact with it, the top film can be sealed and unsealed multiple times.

Furthermore, between the top film and the inner edge of the fixed part of the edge and the notch, 0.5 to 10 m+a, preferably 1.5
By providing a spacing of ~5III+, the peel strength from the inside of the container can be significantly increased compared to the peel strength from the outside of the container.

As a means for forming the incision, the incision is formed using a generally U-shaped or V-shaped annular pressing body, which is preferably pressed by a cutting blade or a heating blade. When pressing and hot pressing are used together, it is preferable that the surface layer of the multilayer sheet, which is the innermost layer of the container, be made of a resin with a lower melting point and lower softening point than the layer in contact with it, and that its thickness be 200 μm or less. .

The incisions can also be formed by press-molding the multilayer sheet material through a non-melting material such as a resin or metal having a higher melting point or softening point than the surface layer material of the multilayer sheet. That is, the present invention uses a multilayer sheet material having at least two layers, a surface layer and a layer laminated to the surface layer via an adhesive, to form a recess with a desired shape and size and having the surface layer as the innermost layer. A container having a flat edge around the periphery is formed, the container is filled with contents, and the container has a top having a lid portion having an area sufficient to cover the edge and a tab portion extending therefrom. After the film is placed on the edge through a non-melting material having a shape and size capable of covering the outer peripheral portion of the boundary area between the recess and the edge, a heat-sealed part and the boundary are placed above the edge. By thermally welding the convex portion for heating and pressing along the region using a heat seal ring having a non-heat sealing portion, the container is sealed, and the concave portion and the edge portion in the innermost layer are sealed. The present invention also provides a method for manufacturing a sealed packaging container, characterized in that forming a cut along the boundary area of the container is performed at the same time.

According to this method, the top film and the edge can be thermally welded and the cuts can be formed at the same time.

The present invention will be explained in more detail below based on the accompanying drawings.

FIG. 1 is an elevational sectional view of a sealed packaging container according to one embodiment of the present invention. The container 10 has a recess 11 and a flat edge 12 along its periphery, and has a generally hat-like cross-sectional shape. The container 10 is made of a two-layer synthetic resin sheet 12
a and 12b, and those layers are adhered with an adhesive. In FIG. 1, the adhesive layer C is indicated by a line. For convenience of explanation, the sheet on the inside of the container will be referred to as the inner layer sheet a, and the sheet on the outside of the container will be referred to as the outer layer sheet b.

A cut 13 is made in the inner layer sheet a of the bonded synthetic resin sheet on the upper surface of the edge along the boundary area between the recess 11 and the edge 12. The tube film 20 has a lid portion 21 having an area sufficient to cover the opening and edge 12 of the container IO, and a tab portion 22 extending from the lid portion 21. The top film 20 may be a single synthetic resin sheet. The lid portion 21 is firmly adhered to the surface of the edge 12 of the container 1o using, for example, a strong adhesive. Instead of using an adhesive, a synthetic resin material of the same type may be used and firmly heat-welded. The adhesive strength between the lid part and the edge is determined by the two-layer synthetic resin sheet 12 in the multilayer sheet.
It is necessary that the adhesive force be stronger than that of the adhesive that adheres a and 12b. The knob portion 22 is located at the edge 12
in contact with the surface of Not worn. The package is stored in the recess before the top film 2o is adhered to the container 1.0.

FIG. 2 is an elevational sectional view showing a portion of the sealed packaging container shown in FIG. 1, and shows a state in which the top film 20 is about to be opened.

When the knob portion 22 is pulled in the direction of arrow A,
Inner layer sheet portion 12 outside the cut 13 of the edge portion 12
a has a stronger adhesive force with the lid portion 21 than the sheet portion 12b.
Since the adhesive force is stronger than that of the adhesive, it is peeled off by the adhesive layer C, pulled together with the top film 20, and peeled off. Then, at the notch 13, the inner layer sheet 12a is
is cut, and the top film 20 is opened.

The inner layer sheet portion 1 is included in the opened top film 20.
2a is attached, and sheet portion 12a and sheet portion 1
Adhesive remains on the surface from which 2b has been peeled off. Therefore, those surfaces can be adhered and sealed with the adhesive by pressing the top film again.

FIG. 3 is a bottom view of the sealed packaging container of FIG. 1. A knob portion 22 that is not fixed to the edge portion 12 of the container 10 is visible and protrudes upward. The cut 13 is shown in dotted lines. As can be seen from FIG. 3, the notch 13 is
A portion 23 located on the opposite side from the knob portion 22 is not provided.

This portion 23 supports the lid 20 so that it does not separate from the container 10, and functions as a hinge when opening and closing the lid. At this time, both ends of the notch 13 are Advantageously, they extend at a right angle or at an angle close to a right angle. This provides some resistance when the inner sheet portion 12a is torn beyond both ends of the notch 13 by the pulling force applied to the tab portion when the lid is opened. If necessary, by providing round holes at both ends of the notch 13, it is possible to prevent the inner sheet from being torn at the hinge portion. These round holes may be provided only in the inner layer sheet, or may be provided throughout the multilayer sheet material.

FIG. 4 is an elevational view of a sealed packaging container according to another embodiment of the present invention. The difference from the one in Figure 1 is container 10.
and top film 20 are fixed by heat welding at the container edge 12, and a space is provided between the inner edge of the heat weld and the notch. Inner layer sheet a and outer layer sheet b
is laminated with a polyacrylic acid ester adhesive.

Next, an embodiment of the method of the present invention according to claim 6 for forming incisions in the sealed packaging container of the present invention will be described based on the drawings. FIGS. 5 and 6 are cross-sectional explanatory views showing an example in which thermal welding and incision formation of the sealed packaging container of the present invention are performed simultaneously.

- The heat-sealing ring 30 is integrally provided with a heat-sealing portion 31 for thermal welding and an annular body 32 (heat-pressing convex portion) for heating and pressing at a distance t from the heat-sealing portion. After filling the container with the contents, a non-thermal adhesive layer is placed on the inner sheet of the container as shown in the figure, a top film is further placed on the container, and the container is heated and pressurized using a heat seal ring 30. Thereby, thermal welding and formation of the notch can be performed simultaneously. In addition, in this way, it is possible to simultaneously perform thermal welding and the formation of incisions at a constant rate, and furthermore, it is possible to perform thermal welding and formation of incisions without damaging the shape of the container.

Although the sealed packaging container and method for manufacturing the same of the present invention have been described above through embodiments, the present invention is not limited to these embodiments. Various modifications and applications are possible without departing from the technical idea of the present invention.

For example, the multilayer sheet material used as the material for the container does not need to be a two-layer multilayer sheet material, it may be a multilayer sheet material of three or more layers, and it does not need to be a synthetic resin multilayer sheet material. . Furthermore, a material laminated with aluminum foil or other materials may be used as the top film.

〔Example〕

A top film is heat welded to a container made of a multilayer sheet material with a sheet thickness of 785 μm, consisting of a high-density polyethylene inner layer sheet a with a thickness of 60 μm, an adhesive layer with a thickness of 25 μm, and a polypropylene outer layer sheet B with a thickness of 700 μm. The distance t from the inner edge to the notch was 4 mm. The peel strength of this container in the opening direction is at a peel rate of 300.
The width is 1.17kg/25+m in mm/min, and the peel strength in the unopened direction (opening direction from the inside of the container) is 4.25k.
It was g/25 cabinet width. From this, it can be seen that the container has excellent sealing properties against internal pressure and is excellent in opening properties when taking out the contents.

Next, the results of measuring the resealing strength and resealing airtightness of the sealed packaging container obtained as described above are shown below.

The resealing strength is the peel strength in the unsealing direction of the resealed packaging container after the operation of fixing the top film to the container with an adhesive is repeated a predetermined number of times after opening the sealed packaging container.
The results were measured at 0 mm/min and are shown in Table 1.

Table 1 Initial 2 times 5 times 10 times 15 times 20 times Re-opening strength 1.17 0.83 0.63 0.60 0.58
0.58 (kg/25mm width) Resealing airtightness refers to the airtightness of a resealing packaging container after opening the container and then fixing the top film to the container with adhesive for a predetermined number of times.
Measured according to. In addition, measurements were also made on unopened products and those opened with a cutter for comparison. Measurements were carried out at a temperature of 40±1°C, a humidity of 90±2%, and an air flow of 1 m.
The sample was left for a predetermined number of days under the condition of 100 g of calcium chloride, and the weight (g) of moisture absorbed by 100 g of calcium chloride was measured. The results are shown in Table 2.

Table 2 Number of days elapsed 1 3 5 7 Sample unopened 0 0 0.02 Opened 0.052 times 1.0 15 36 Opened 625 times
1.5 24 55 73 cutter opened
38 61 86 114 From the above results, it can be seen that the sealed packaging container of the present invention has better sealing performance than a container that is completely opened.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a disposable sealed packaging container that can tightly seal and package products for multiple uses, is easy to open, and has a top film that allows the lid to be reused for opening and closing multiple times after opening. I was able to do that. Further, according to the method of the present invention, such excellent sealed packaging containers can be manufactured extremely efficiently.

[Brief explanation of the drawing]

FIG. 1 is an elevational sectional view of a sealed packaging container according to one embodiment of the present invention. FIG. 2 is a partial sectional view of a portion of FIG. 1, showing a state in which the top film is about to be opened. 3 is a bottom view of the container of FIG. 1; FIG. FIG. 4 is an elevational sectional view of another sealed packaging container according to Mr. B of the present invention. FIG. 5 is a partial cross-sectional explanatory view showing a method for simultaneously sealing a container and forming a cut. FIG. 6 is a partial sectional view of a sealed packaging container obtained by the method shown in FIG. 5. [Explanation of symbols] 10: Container 11; Recess l2: Edge a: Innermost layer of the container b = Layer in contact with the innermost layer of the container C: Adhesive layer 13: Notch 20 Nidotsubu film 21: M portion 22: Knob portion 23: Hinge part 24: Heat seal part 25: Non-melting material 30: Heat seal ring

Claims (1)

[Claims] 1. Molded from a multilayer sheet material having at least two layers: a surface layer and a layer laminated to the surface layer via an adhesive, having the surface layer as the innermost layer, and having a recessed portion. a container having a flat edge around the periphery, a notch in the innermost layer on the upper surface of the edge along a boundary area between the recess and the edge; A sealed packaging container comprising a top film having a lid portion firmly fixed on the outside of the notch and a tab portion extending from the lid portion and not fixed to the edge surface. 2. The sealed packaging container according to claim 1, wherein a distance of 0.5 to 10 mm is provided between the inner end of the lid portion and the fixed portion of the edge and the notch. 3. The sealed packaging container according to claim 1, wherein the notch is provided in the innermost layer on the upper surface of the edge in an arc shape leaving a hinge portion along the boundary area between the recess and the edge. 4. The sealed packaging container according to claim 3, wherein round holes are provided in the multilayer sheet at both ends of the notch provided in the innermost layer. 5. Using a multilayer sheet material having at least two layers: a surface layer and a layer laminated to the surface layer via an adhesive, the surface layer is used as the innermost layer, and a recess of a desired shape and size is formed. A container having a flat edge around the periphery is formed, an incision is made in the innermost layer above the edge along the boundary area between the recess and the edge, and the edge is filled with the contents. A top film having a lid portion having an area sufficient to cover the edge and a tab portion extending from the top film is firmly fixed to the edge surface outside the cut, excluding the tab. A method for manufacturing a sealed packaging container characterized by: 6. Using a multilayer sheet material having at least two layers: a surface layer and a layer laminated to the surface layer via an adhesive, apply the material to a recess of a desired shape and size having the surface layer as the innermost layer and its surroundings. Molding a container having a flat edge, filling the container with contents, and applying a top film to the container having a lid portion having an area sufficient to cover the edge and a tab portion extending therefrom, After covering the edge with a non-melting material having a shape and dimensions capable of covering the outer peripheral portion of the boundary area between the recess and the edge, a heat-sealed part is placed above the edge and along the boundary area. By thermally welding a convex part for heating and pressing through a non-heat sealing part using a heat seal ring, the container is sealed and the boundary area between the concave part and the edge part in the innermost layer is sealed. 1. A method for manufacturing a sealed packaging container, comprising simultaneously forming a cut along the .