CA1144729A

CA1144729A - Method for making a container having a soft, pliable wall

Info

Publication number: CA1144729A
Application number: CA000391910A
Authority: CA
Inventors: Masaaki Fujio
Original assignee: Fuji Seal Inc
Current assignee: Fuji Seal Inc
Priority date: 1978-02-27
Filing date: 1981-12-09
Publication date: 1983-04-19
Also published as: DE2906680A1; GB2015473A; CA1158209A; IT7920533A0; FR2418160B1; IT1111914B; DE2906680C2; FR2418160A1

Abstract

ABSTRACT OF THE DISCLOSURE

A method is provided for making a container which has a soft and pliable side wall and is formed of a heat-shrinkable film, e.g., one formed of polypropylene, polyvinyl chloride, polyethylene, poly-ester or a laminate of such synthetic resins, of 0.004 to 0.2 mm in thickness. The method involves the first step of placing a heat-shrinkable tubular film which has one closed end over a former. The excess film of the closed end is then wrinkled over the former. Hot air is then directed onto this excess film so as to shrink it onto the former, e.g., by at least 3%. Such container is both simple and robust.

Description

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This invention relates to a method for making containers of which at least a part is made of heat~shrinkable film, e.g., synthetic resin.
This application is a division of pending application Serial No. 322,123 filed February 23, 1979.
Various conventional containers made of flexible film,e.g., paper or synthetic resin film, are well known. Exemplary of these is the shopping bag. However, when filled with solid objections powder, or the like, these known ccntainers have the disadvantage that they are usually unstable when stood upright on their bottoms, since the way in which these bottorns are sealed does not usually allow for them to open flat, and perpendicular to the sides of the containers. Further, if the containers are placed on a sharp or rough surface, there is a danger that their bottoms may be punctured by the surface, thus rup-turing the containers. Thus, often, a reinforcing member is required to strengthen the bottom of such a container. Such a reinforcement is also often required to support the weight of a heavy load charged into the container. Therefore, there has up till now been lacking a design for a simple and robust container, which is substantially free from the aforementioned defects.
It is therefore an object of an aspect of the present invention to provide an improved method for making a container which is substantially free from the above-mentioned defects and one which is strong, simple, and useful.
According to an aspect of the present invention, a method is provided for making a container which comprises the steps of: placing a heat-shrinkable tubular film which has one end closed over a former;

wrinkling the excess film of the closed end over the former; and then directing hot air onto this e~cess film so as to shrink it onto the former.
By one variant, the heat-shrinkable film is a synthetic resin, shrinkable by heat by at least 3~/0.
By another variant, the film is polypropylene~ polyvinyl chloride, polyethylene, polyester or a laminate of such synthetic resins.

By yet another variant, the film is 0.004 to 0.2 mm in thickness.
In the accompanying drawings, Figure 1 is a perspecCive view of a container which is an embodiment of one aspect of the invention disclosed in the above-identified parent application Serial No. 322,123;
Figure 2 is a longitudinal cross-section of the container of Figure l;
Figure 3 is a longitudinal cross-section of another embodimerlt of another aspect of containers which may be formed by the method of aspects of the present invention;

Figure 4 is a longitudinal cross-section of two exarnples of still another embodiment of aspects of containers which may be formed by the method of aspects of the present invention showing them as stacked up on one another;
Figures 5(a) and 5(b) are schematic views of a method for producing a container, according to another aspect of the invention disclosed in the above-identified parent application Serial No. 322,123;
Figure 6 is a perspective view of the material for making a container according to an aspect of the invention disclosed in the above-identified parent application Serial No. 322,123 to be used in the method

- 2 -7~9 of an aspect of the invention schematically illustrated in Figure 7;
Figures 7(a) and 7(b) are schematic views of a method for producing a container according to an aspect of the present invention;
Figure 8 is a longitudinal cross-~ection of another embodiment of a container according to another aspect of the invention disclosed in the above-identified parent application Serial No. 322,123;

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- Figure 9 is a perspective view of the container of Figure 8;
Figure 10 is a longitudinal cross-section of the container of Figure 8, while it is in use;
Figure 11 is an elevational view of another embodiment of a : container according to another aspect of the invention disclosed in the above-identified parent application Serial No. 322,123;
Figure 12 is a longitudinal cross-section, taken along the line XII - XII in Figure 11;
Figure 13 is an elevational view of another embodiment of another aspect of the invention as disclosed in the above-identified parent application Serial No. 322,123;
Figures 14 and 15 are perspective views of other embodiments of containers according to others aspects of the invention as disclosed in the above-identified parent application Serial No. 322,123;
Figures 16(a), 16(b), 16(c) and 17 are longitudinal cross-sections of still other embodiments of containers according to still other aspects of the invention as disclosed in the above-identified parent appli-cation Serial No. 322,123;
Figures 18(a), 18(b), and 18(c) are cross-sections of synthetic resin films having air cells,which are used for prod~lcing containers according to various aspects of the invention as disclosed in the above-identified parent application Serial No. 322,123;
Figures l9(a) and 19(b) are schematic views of a m~thod for producing the container of Figure 17 according to an aspect of the inven-tion as disclosed in the above~identified parent application Serial No.
322,123;
Figure 20 is a longitudinal cross-section of another embodi~lent of a container according to another aspect of the invention as disclosed in the above-identified parent application Serial No. 322,123;

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~igure 21 is a longitudinal cross-section of yet a~other embodi-ment of a container according to yet another aspect of the invention as disclosed in the above-identified parent application Serial No. 322,123;
Figure 22 is a perspective view of yet another embodiment of a container according to yet another aspect o the invention as disclosed in the above-identified parent application Serial No. 322,123; in use.
Figure 23 is a longitudinal cross-section of the container of Figure 22, taken along the line XXIII - XXIII;
Figure 24 is an exploded perspecti.ve view of the container of Figure 22;
Figures 25 and 26 are longitudinal cross-sections of other embo-diments of containers accordi.ng to other aspects of the invention as dis-closed in the above-identified parent application Serial No. 322,123;
Figure 27 is a perspective view of the container of Figure 26, in use;
Figures 28, 29, and 30 are longitudinal cross-sections of yet still other embodiments of containers of yet still other aspects of the invention as disclosed in the above-identified parent application Serial No. 322,123; and Figure 31 is a perspective view of another embodiment of a con-tainer of another aspect of the invention as disclosed in the above-identified parent application Serial No. 322,123, in use.
In the figures, like reference numerals with different suffix letters in the different figures denote corresponding parts.
The heat-shrinkable film material used in aspects of the present invention may be polypropylene, polyvinyl chloride, polyethylene, poly-ester, a laminate thereof, or the like. The thickness of the film material should be in the range of 0.004 to 0.2 mm, and the shrinkage of it by heat ~'~

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should be at least 3%.
Referring to Figures 1 and 2, there is shown a container I accor-ding to àn aspect of the invention as disclosed in the above-identified parent application Serial No. 322,123, which comprises a cylindrical side wall 2 made of a soft heat-shrinkable film material, and a circular bottom

3, made of a substantially harder and less flexible and pliable material, e.g., synthetic resin, cardboard, or the like, the side wall 2 being coupled to the bottom by a coupling portion 4, which is a part of the side wall 2, and which is folded inwards and heat-sealed to the bottom, as is hereafter described. This container may, of course, be charged with con-tents, and often the top 5 of it is then heat-sealed.
The shape of the bottom 3, of course, is not restricted to be circular; it may be rectangular, elliptical, triangular, and so forth.
In Figures 3 and 4, other containers la and lb according to a broad aspect of the present invention are shown. These differ somewhat from the container of Figures 1 and 2, in that the bottom is not separate from the wall, but is formed in one piece with it out of a heat-shrinkable film. However, the bottom is substantially harder and less pliable than the film of the side walls, both because it is thicker, and because in fact it has been shrunk. These containers have been made by the process illus-trated in Figure 7.
The containers of Figure 4 are so formed as to stack up conveni-ently on one another.
Figure 5 illustrates a method according to an aspect of the invention as disclosed in the above-identified parent application Serial No. 322,123 for producing the container 1 of Figures 1 and 2. A heat-shrinkable tube 2 and a hard bottom plate 3 are set on a former 20, as shown in Figure 5(a), with the edge of the tube 2 around the plate 3 and protruding slightly above it. Then the projecting edge of the tube is ~L~L4~29 folded down against the plate 3, to make the coupling portion 4, and the heat plate 21 is lowered down onto it and heat seals it to the bottom.
Then the finished container is released from the former 20.
In Figure 7 is shown a method according to a broad aspect of this invention for producing the container shown in Figure 3.
A heat-shrinkable tubular film with its end sealed in a U-shaped round bottom 6, as shown in Figure 6, is placedon the former 20, and the round bottom 6 is pressed down to contact with the upper surface 22 of the former 20, so as to cause wrinkles, as shown in Figure 7(a). Then hot air 23 is directed onto the wrinkled bottom 6, and thereby the bottom 6 is shrunk, as shown in Figure 7(b). The finished container is then released from the former 20.
The bottom 3a of the finished container is much stiffer than its wall, both because it is somewhat thicker and denser than the wall, due to the surplus of material which originally formed the wrinkles, before heat-shrinking, and because due to the heat-shrinking, it has lost some oE its flexibility.
In Figures 8 - 10 is shown another container lc, which has the same construction as the one of Figure 1, except that a reclosable sealant member, i.e., a ZIPPER comprising a convex member 9cl and a concave member 9c2 is attached to the upper inner surface of the side wall 2c, instead of sealing the open top. Thus the open top can be sealed as shown in Figure 10, and can be opened and resealed again, which is very useful.
In Figures 11 and 12 is shown another container ld according to another aspect of the invention as disclosed in the above-identified parent application Serial No~ 322?123. This container is sealed along a sealing line 8d by heating, and the unnecessary part 11 of the side wall 2d is cut off.
In Figure 13 is shown another container le according to another 7~9 aspect of the invention as disclosed in the above-identified parent appli-cation Serial No. 322,123, in use. The container is sealed according to the form of the contents therein, by heating.
In Figures 14 and }5 are shown other containers lf and lg of other aspects of the invention as disclosed in the above-identified parent application Serial No. 322,123 which have the same constructions, except that a pair of handles 9f are provided on container lf,and a pair of holes 9g are provided in container lg for lifting them.
In Figure 16 are shown other containers lh according to other aspects of the invention as disclosed in the above-identified parent appli-cation Serial No. 322,123, which are similar to the aforementioned ones, except that in Figure 16(a) the bottom is concaved, i.e., the bottom pro-jects downwardly, 3h in 16(b). It is convexed, i.e., it protrudes inward-ly, 3h, and in the Figure 16(c) two containers are provided which have one common piece of material for their bottoms. This could be of particular use in special applications~
In Fi~ure 17 is shown another containér li, of another aspect of the invention disclosed in the above-identiied parent application Serial No. 322,123, which is particularly distinguished by the fact that the materials of which the side wall and bottom are formed have air cells formed in them. This container has good cushioning effect on the contents9 and also has heat resistance.
Figure 18 shows the sort of material of which the container of Figure 17 is made. The air cells could be on either the inside (Figure lôa)) or the outside of the con~ainer (Figure 18(bj). As another possibility, (Figure 18(c)), they could be provided on both sides of the wall and bottom.
Figure 19 shows the method of another aspect of the invention as disclosed in the above-identified parent application Serial No. 322,123 by which the container of Figu{e 17 is made. This is similar to the method '7~9 described for Figures 5(a) and 5(b) except that the heat plate 21 has to have a cutaway in it, so as not to break the air cells in the bottom while heat-sealing the wall to the bottom.
In Figure 20 is shown a container lj according to yet anoLher aspect of the invention as disclosed in the above-identified parent appli-cation Serial ~o. 322,123, which has air cells in the wall but not in the bottom; and in Figure 21 is shown a container lk of that sort, formed as a double container, with one piece of material serving as the bottom of two containers.

In Figures 22 - 24 is shown another container 1 ~ , of another aspect of the invention as disclosed in the above-identified parent appli-cation Serial No. 322,123 whnich comprises a side wall 2 ~ which is made of a pair of heat-shrinkable film pieces by sealing the longitudinally oppo-site sides 12 together, and which has an elliptical hard bottom plate 31Q
which is coupled to the side walls 2 ~ at a coupling portion 4~ of them, by heat sealing, in the same manner as described above.
This contain~r also includees a reclosable sealant member 9 ~2, and which is attached to the upper inner side wall ~ ~. The contents, designated by 10 2 , are put into the container, and the ZIPPER is closed.
Then the container 1~ is further heat-sealed above ~he ZIPPER 9~, the sealed portions being designed in the figure by 8J~. When the contents are to be first used, the upper sealed portions are cut off, and the ZIPPER is opened, and thereafter may be used to reseal the container.
In Figure 25 is shown another container of another aspect lm of the invention as disclosed in the above-identified parent application Serial No. 322,123, which is of the same construction as the one in Figure 1, except that the cylindrical side wall 2m is made of a heat-shrinkable net. This container is useful for packing fruit or the like.
In Figures 26 and 27 is shown another container ln of another ~4'729 aspect of the invention as disclosed in the above-identified parent appll-cation Serial No. 322,123, which is the same as the container of Figure 25, except that it has a bottom formed as the frustrum of a cone, 3n. The open top may be tied shut by a ribbon 13n.
In Figure 28 is shown another container of yet another aspect lp of the invention as disclosed in the above-identified parent application Serial No. 322~123, which is of the same construction as that of Figure 1, except that the bottom member 3s is made of polystyrene foam, and is of substantial thickness, with a pocket formed therein adapted to receive a fruit, and further that the cylindrical side wall 2p includes a plurality of small openings14 for ventilating the inside of the container.
In Figure 29 is shown another container lq of still another aspect of this invention as disclosed in the above-identified parent appli-cation Serial No. 322,123. This container is similar to that shown in Figure 28, exdept that the side wall 2q which is made of a heat-shrinkable film and which is heat-sealed to the polystyrene bottom extends only a short way upwards, and is t~hen heat-sealed or secured by adhesive to a non-heat-shrinkable cylindrcal film 2q at an overlapping portion 15.
In Figure 30 is shown another container lr of yet another aspect of the invention as disclosed in the above-identified parent application Serial No. 322,123, which is the same as the one shown in Figure 28, except that no small openings are formed in the side wall 2r, and that the bottom member 3r includes a groove 16 around its lower periphery, into which a coupling portion 4r of the wall 2r is sealed by heat-sealing.
In Figure 31 is shown another container ls of a further aspect of the invention as disclosed in the above-identiied parent application Serial No. 322,123 which is the sme as the one shown in Figure 28, except that no small openings are formed in theside wall 2s. The open top is sealed by a ribbon 13s.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of making a container which comprises the steps of: placing a heat-shrinkable tubular film which has one end closed over a former; wrinkling the excess film of the closed end over the former;
and then directing hot air onto this excess film so as to shrink it onto the former.

2. The method of claim 1 wherein said heat-shrinkable tubular film is a synthetic resin, shrinkable by heat by at least 3%.

3. The method of claim 2 wherein said film is polypropylene, polyvinyl chloride, polyethylene, polyester or a laminate of such synthetic resins.

4. The method of claims 1, 2 or 3 wherein the film is 0.004 to 0.2 mm in thickness.