JPH0329644B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing sealed paper containers.

Although paper as a material for containers has favorable properties such as excellent shape retention and light weight, it also has unfavorable properties such as its strength becoming significantly weakened when water or oil soaks into it.

For this reason, when paper is used as a container material, it is generally used, for example, as a laminate consisting of a central layer containing paper and protective layers covering both sides of the central layer. In such a laminated material, the protective layer and the like can effectively prevent water, oil, etc. from seeping in from both sides and weakening the paper.

However, at the cut edge of the laminate, the paper is not covered by a protective layer and is exposed. Therefore, unless this cut edge is properly treated, a container that is resistant to water, oil, etc. cannot be obtained.

On the other hand, in order to form a sealed paper container, it is common to connect the open end of the body having the cut edge as described above and the lid in a sealed manner.

The present invention has been made in view of the above situation.

An object of the present invention is to provide a method for manufacturing a sealed paper container in which a thermoplastic resin film is adhered uniformly and stably to the open end of the body, thereby having excellent sealing performance and impact resistance. It is to provide.

Another object of the present invention is to connect the open end of the body to the lid via a thermoplastic resin film adhered to the open edge of the body, thereby providing a sealing structure that is highly productive. An object of the present invention is to provide a method for manufacturing a paper container.

Another object of the present invention is to connect the open end of the barrel to the lid without deforming the open end of the barrel at all or only slightly, thereby providing an opening in the barrel. To provide a method for manufacturing a sealed paper container in which wrinkles do not occur at the edges, etc.

According to the present invention, in a method for manufacturing a sealed paper container by joining a lid and a body made of a laminated material containing paper, , a thermoplastic resin film is pasted so that a part of it protrudes from the open end, and the part of the thermoplastic resin film that protrudes from the open end is attached to the edge of the open end and to this. Bend inward so as to wrap around the inner peripheral surface, press and adhere the part of the thermoplastic resin film to the inner peripheral surface of the open end, and connect the open end of the body and the lid. A method for manufacturing a sealed paper container is provided, which comprises connecting the container to a surrounding portion via the thermoplastic resin.

Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

According to a first embodiment of the present invention, a paper container as shown in FIGS. 1 and 2, for example, is manufactured.

This paper container includes a body 10 and a lid 12, and a thermoplastic resin film 16 that protects the edge 14 of the body 10 is interposed between the open end 11 of the body 10 and the lid 12.
The peripheral portion 13 of

As shown in FIG.
0 and protective layers 22 and 24 on both sides thereof. The edge 14 of the body 10 is covered with a protective layer 2
2 and 24. The protective layers 22 and 24 are made of a polyolefin resin such as polyethylene, polypropylene, ethylene propylene copolymer, acid-modified polyolefin, ionically crosslinked acid-modified polyolefin, ethylene vinyl acetate copolymer, ethylene acrylic acid copolymer, or polyester resin. Alternatively, it can be made of polyamide resin or the like. Including the paper 20 in the laminated material forming the body 10 is preferable in view of the shape retention properties of the body 10 .

Other material compositions of the body 10 include an innermost protective layer, such as PE (polyethylene) or polypropylene, and successively outer layers of aluminum foil, PE, etc.
Alternatively, a laminate consisting of polypropylene, paper and an outermost protective layer, for example PE or polypropylene, can be used. Alternatively, the material composition can also be a laminate consisting of an innermost protective layer, e.g. PE or polypropylene, and PET (polyethylene tereftate), aluminum foil, PE, paper, and an outermost protective layer, e.g. PE or polypropylene. Can be used. Providing a layer of aluminum foil or PET between the innermost protective layer and the paper can prevent the contents inside the container, such as oxygen, from penetrating the paper and strengthen the container. The thickness of each layer constituting the laminated material can be appropriately selected in consideration of the characteristics of the contents to be accommodated, the size of the container, etc.

The body portion 10 is formed, for example, by forming a cylindrical body from the same laminated materials as described above. The cylindrical body is formed, for example, by joining side edges of a rectangular laminate, ie by side seams. The side edges can be joined by joining a part of the inner surface of one side edge and a part of the outer surface of the other side edge, that is, by lap joining. joining the end face and the other side edge;
That is, by butt joining, or by joining parts of the inner surfaces of both side edges so as to protrude outward in the radial direction, and after that, part of the outer surface of one side edge is formed into a cylindrical shape. It may also be formed by joining the palms together on the outer circumferential surface of the body. The cylindrical body can also be formed by spirally winding a strip of laminated material and joining the side edges of the strip of laminated material, that is, by spiral joining. These bonds are performed by thermal adhesion of the protective layers, adhesion using an adhesive, or the like.

The thickness of the body 10, and therefore the thickness of the laminated material, is 0.2 to 0.7 mm when the body 10 is formed by the side seams, and the thickness of the paper material is 0.17 to 0.7 mm.
It is preferably 0.6 mm (approximately 150 to 500 g/m ² in terms of basis weight). When formed by spiral bonding, the thickness is preferably 0.5 to 3.0 mm, and the thickness of the paper material is preferably 0.4 to 2.5 mm.

In this example, the lid is made of a laminated material similar to the body 10, and in the illustrated example, the lid is made of a paper 26.
and protective layers 30 and 32 on both sides thereof.

The thermoplastic resin film 16 is made of a resin that has good adhesive properties with the protective layers 22, 24, 30, and 32 of the laminate. Preferred resins include polyolefin resins, polyester resins, and polyamide resins. As shown in FIG. 2, the thermoplastic resin film 16 is connected to cover the upper edge 14 of the body 10 and the inner and outer protective layers 22 and 24 continuous thereto. This can prevent water, oil, etc. from entering from the upper edge 14 of the body 10 into the paper of the laminated material forming the body 10. The thickness of the thermoplastic resin film 16 is preferably 5 to 200 microns, more preferably 30 to 100 microns. Further, the width 1 of the covering layer 16 adhered to the inner and outer protective layers 22 and 24 is preferably 1 to 10 mm, more preferably 2 to 5 mm.

Next, a first specific example of the present invention for manufacturing a paper container as described above will be described with reference to FIGS. 1 to 3.

First, the body portion 10 is formed as described above. The lower open end of the body 10 is closed by the methods described below or by other methods.

A thermoplastic resin film 16 is attached to the outer peripheral surface of the upper open end 11 of the body 10. A thermoplastic resin film that has been previously formed into a band shape may be used, or a band-shaped thermoplastic resin film may be manufactured using an extruder or the like and simultaneously attached to the outer periphery of the opening end. By heating either or both of the thermoplastic resin film 16 and the outer protective layer 24 of the body 10 by hot air heating, infrared heating, hot roll heating, etc., these are bonded together.
Alternatively, it may be bonded using an adhesive. The thermoplastic resin film 16 is attached to the outer periphery of the upper open end 11 of the body 10 so as to have a protruding portion 40, as shown in FIG.

Next, the protruding portion 40 of the thermoplastic resin film 16 is bent inward so as to wrap around the edge 14 of the opening and the inner circumferential surface following the edge 14 of the opening. That is,
As shown in FIG. 3, the portion of the adhered thermoplastic resin film 16 that is not bonded to the outer protective layer 24 of the body 10, that is, the protruding portion 40, is first bent toward the right side in FIG. That is, it is bent inward and brought into contact with the edge 14 of the body 10, and then bent downward and brought into contact with the protective layer 22 inside the body 10. Such bending can be accomplished, for example, by rotating the body 10, applying the thermoplastic resin film 16 to the open end of the body 10 sequentially from one end in the longitudinal direction, and then using a plurality of rollers to bend the thermoplastic resin film 16. This can be done by forcing the film 16 inwardly and downwardly.

Instead of the inward bending using the plurality of rollers described above, the inward bending can also be done using a die 42 and core 46 as shown in FIG.

To explain in detail, the die 42 has an open end insertion hole 4
8. It has a stepped portion 50 that is kneaded into the open end insertion hole 48 and extends radially inward, and a core insertion hole 52 that is connected to the stepped portion 50. These form a substantially cylindrical hole.

The open end insertion hole 48 has a truncated conical guide surface 54 and a short cylindrical guide surface 56, and the inner diameter of the short cylindrical guide surface 56 is equal to the outer diameter of the open end 11.
D ₂ , and the thickness of the thermoplastic resin film 16 is t, which is approximately equal to (D ₂ +2t), that is, the thickness is large enough to fit the open end 11 to which the thermoplastic resin film 16 is bonded to the outer peripheral surface. It is determined that

Note that without providing the short cylindrical guide surface 56,
The guide surface may be formed only by the frusto-conical guide surface 54. However, the provision of the short cylindrical guide surface 56 makes it possible to reliably bend the thermoplastic resin film 16, which does not have very good bendability, or to create an overlap part in the thermoplastic resin film 16 that is thermally bonded to the outer peripheral surface of the opening end 11. If this occurs,
By crushing the step to ensure a uniform thickness along the entire circumference, or by clamping and pressing the inner peripheral surface of the open end 11 of the folded protrusion 40 with the core 46 described later, This is effective in that deformation due to expansion of the opening end portion 11 can be prevented.

The radial width of the stepped portion 50 is substantially determined by the sum of the thickness of the open end portion 11 and the thickness t of the thermoplastic resin film 16. Therefore, when the open end 11 is inserted into the die 42 through the open end insertion hole 48, the protruding portion 40 is bent approximately radially inward when it hits the stepped portion 50.

The core insertion hole 52 has a short cylindrical guide surface 62 and a truncated conical guide surface 64 for guiding the core 46 connected to the stepped portion 50 . The inner diameter of the short cylindrical guide surface 62 is substantially equal to the inner diameter D ₃ of the open end 11 .

The insertion tool, ie, the core 46, has a generally cylindrical shape as a whole, as shown in FIG. 4, and includes a rigid core 70 and a sleeve 72 made of, for example, heat-resistant elastic rubber. The sleeve 72 consists of a tapered part 74 formed at the tip and a cylindrical part 76, and the tapered part 74 makes it easy to push into the core insertion hole 52. The outer diameter of the cylindrical portion 76 is determined to be at least the value obtained by subtracting twice the thickness t of the thermoplastic resin film 16 from the inner diameter D ₃ of the open end portion 11, that is, at least (D ₃ −2t), and The core 46 is inserted into the die 42 through the core insertion hole 52, and the protruding part 40 extending approximately radially inward is folded back by the sleeve 72, and the folded protruding part 40 is inserted into the open end 11. inner peripheral surface 2
2 and the sleeve 72, so that it can be pressed elastically. At this time, the open end 11
Thermoplastic resin film 16 adhered to the outer peripheral surface
is supported by a short cylindrical guide surface 56 of the open end insertion hole 48.

The elastic rubber forming the sleeve 72 is preferably one that has excellent heat resistance, abrasion resistance, and releasability from the thermoplastic resin film 16 that is melted or softened and solidified, such as fluororubber or silicone rubber.

Using the die 42 and core 46 as described above, the protruding portion 40 of the thermoplastic resin film 16 is
The method of adhering the protective layer 22 on the inner side of the body portion 10 may be by fusion by heating or by adhesion using an adhesive. In the case of heat bonding,
Immediately before the adhesive film 16 is bent, the protective layer 22 on the inside of the body 10 is heated with hot air, etc., and the core 4 is bonded at the same time as the bending.
An effective method is to heat 6 and then bond it immediately after bending. If desired, the edge 14 of the body 10 of the thermoplastic resin film 16 may be
It can also be bonded using an adhesive.

Next, the contents are filled into the body 10 and the body 1 is opened.
The lid 12 is adhered to the thermoplastic film 16 which has been adhered to the open end 11 of the body part 10 as described above, thereby connecting the body part 10 and the lid 12. This first
In this specific example, the lid 14 is made of the same laminated material as the body 10. Then, the thermoplastic film 16 and the surrounding area of the protective layer 30 on the inside of the lid 14 are bonded by fusion or adhesive in the same manner as described above.

In the embodiment shown in FIG. 2, the peripheral portion 13 of the lid 14 is bonded to the body portion 10 on all three surfaces of the thermoplastic film 16: the outer surface, the upper surface, and the inner surface. However, this is not necessary and any one of these
It may be configured to adhere only on one or two surfaces. In addition, the lid 14 is attached to the body 1 as described above.
It is made of the same laminated material as 0. Therefore, in the embodiment shown in FIG. 2, the paper 26 of the laminated material of the lid 14 is exposed at the outer peripheral edge. In order to prevent water or oil from penetrating the paper 26 of the lid 14 from this exposed portion, this exposed portion may be wrapped with a thermoplastic resin film, for example, similar to the edge 14 of the body portion 10.

Next, a second specific example of the present invention will be described with reference to FIG.

According to the second specific example, as shown in FIG.
The open end 11' of the body 10' and the lid 12' are connected by double seaming.

Therefore, it is preferable that the lid 12' be made of a material mainly composed of metal. That is, the lid 12' is mainly made of a light metal plate such as aluminum or a steel plate, the surface of which is coated with paint, plastic resin, paper, etc., or a metal plate with various surface treatments such as tin plate or chrome-plated steel plate. be able to. It is preferable that the lid 12' has a thickness of 0.05 to 0.5 mm in consideration of the construction characteristics during seaming.

Furthermore, in the second specific example, similarly to the first specific example, a thermoplastic resin film 16' is attached to the upper open end 11' of the body 10',
The protruding portion is bent and adhered to the inner surface of the open end 11'.

On the other hand, a sealant 38 is applied around the lower surface of the lid 12'. This can be done, for example, by dispersing the sealant in water or a solvent and applying it to the lower peripheral portion 13' of the lid 12. Of course, the edge 1 of the open end 11' above the body 10'
A sealant 38 may be applied to the thermoplastic resin film 16' and the protective layers 22' and 24' covering the 4'. This sealant 38 is, for example,
SBR (butadiene styrene rubber), tackifier,
It is composed of fillers and others (such as surfactants, viscosity modifiers, etc.).

Next, the contents are filled into the body 10', the lid 12' is placed on the body 10', and the circumference 13' of the lid 12' and the body 10' are sealed using a seaming machine. The upper end portion 11' is double-sealed.

By double-sealing the circumference 13' of the lid 12' and the upper end 11' of the body 10', the connection can be made cold, and therefore quick connection is possible.

Example Innermost material made by laminating medium density polyethylene (35 μm) and aluminum foil (15 μm), middle layer material made of two layers of 350 μm thick kraft paper, aluminum foil (12 μm) and low density polyethylene (15μm) A strip sheet of the outermost layer material is prepared,
A spiral pipe was created by applying vinyl acetate adhesive to the material and wrapping each laminated material sheet in a spiral around a fixed mandrel, which was then cut to a certain size and spirally joined to create a body material (inner diameter of the body: 52.3 mm). ,length
135mm) was obtained. At this time, the sheet width of the innermost layer material was made wider than the width of the middle layer material, and the wide portion was bent inward and heat sealed to create a structure in which the aluminum foil of the innermost layer material was not exposed.

Next, while heating the outer periphery of both open ends of the body material sequentially with hot air, a medium-density polyethylene resin film having a thickness of 100 μm and a width of 6 mm was heat-bonded so as to protrude 2 mm from the open end.

Next, the inner circumferential surface of the open end is locally heated with hot air, and the protruding part of the adhesive film adhered to the outer circumference of the open end is cut into a bending die (with a guide hole of 53.85 mm in inner diameter and a 0.70 mm (with a circumferential step)
Then, insert the core with a rubber surface (outer diameter 53.0 mm and has a tapered part) inside the opening end, and while pressing the protruding part inside the body. The laminated end faces of both open ends were completely covered and protected by heat bonding. Both open ends of this body material were flanged by a conventional method.

Next, a tin lid (#202 diameter) with a thickness of 0.22 mm and painted on both sides was prepared, and one open end of the body material was double-sealed using a conventional method.

Orange juice (50% fruit juice) was hot packed into the container thus prepared at 93°C, and the other open end was double wrapped with the above-mentioned tin lid.

When some of the containers were cut out and observed, there was no damage to the open end of the body, which was completely protected by the adhesive film.

Furthermore, after being stored at room temperature for 6 months, we checked for leakage from the seamed parts (300 pieces) and found that no leakage of the contents was observed. Leakage was considered to be a case in which the internal pressure at 25°C was reduced by 5% or more compared to immediately after filling, and a case in which some content was observed to ooze out near the seaming part.

As is clear from the above results, it was found that a paper container with excellent sealing performance could be easily produced according to the method of the present invention.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a sealed paper container manufactured according to a first embodiment of the present invention. FIG. 2 is a partially enlarged sectional view of the sealed paper container shown in FIG. 1. FIG. 3 is a diagram showing a state in which the thermoplastic resin film is adhered to the body according to the first embodiment of the present invention. FIG. 4 is a sectional view of a die and a core for bending the thermoplastic resin film adhered to the body. FIG. 5 shows the second embodiment of the present invention.
FIG. 2 is a partially enlarged sectional view of a sealed paper container manufactured according to a specific example. 10, 10'... Body, 11, 11'... Opening end, 12, 12'... Lid, 13, 13'... Surrounding part, 14, 14'... Edge, 16, 16'... ...Thermoplastic resin film, 20,20'...Paper, 22,
22'... Inner protective layer, 24, 24'... Outer protective layer, 38... Sealing material, 40... Protruding portion,
42...die, 46...middle.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a sealed paper container by joining a lid and a body made of a laminated material containing paper, including: A thermoplastic resin film is attached to the surface so that a part of the thermoplastic resin film protrudes from the open end, and the part of the thermoplastic resin film that protrudes from the open end is attached to the edge of the open end and The following inner peripheral surface is bent inward so as to wrap it, and the part of the thermoplastic resin film is pressed and adhered to the inner peripheral surface of the open end, and the open end of the body and the A method for manufacturing a sealed paper container, the method comprising connecting the peripheral portion of the lid via the thermoplastic resin. 2. A method for manufacturing a sealed paper container according to claim 1, which comprises connecting the open end of the body and the peripheral portion of the lid via the thermoplastic resin and sealant. 3. A method for manufacturing a sealed paper container according to claim 1, which comprises fusing the peripheral portion of the lid and the thermoplastic resin. 4. A method for manufacturing a sealed paper container according to claim 1 or 2, which includes connecting the open end of the body and the peripheral portion of the lid by double winding. .