U.S. patent number 3,700,018 [Application Number 05/104,438] was granted by the patent office on 1972-10-24 for semirigid container.
Invention is credited to Luigi Goglio.
United States Patent |
3,700,018 |
Goglio |
October 24, 1972 |
SEMIRIGID CONTAINER
Abstract
Completely heat-welded, semirigid tight container for foodstuff.
The container comprises a pre-shaped bottom of thermoplastic
material which can be heat-welded, as well as a top containing
portion, at least partly formed of heat weldable material
consistent with that the bottom, formed of a preferably tubular
element which at one of its ends is heat-welded to the bottom and
provided with a top opening suitable to be closed by transverse
heat-welding upon completion of product stuffing.
Inventors: |
Goglio; Luigi (Milan,
IT) |
Family
ID: |
27273067 |
Appl.
No.: |
05/104,438 |
Filed: |
January 6, 1971 |
Foreign Application Priority Data
|
|
|
|
|
Jan 14, 1970 [IT] |
|
|
20494 B/70 |
Feb 18, 1970 [IT] |
|
|
20779 A/70 |
Mar 23, 1970 [IT] |
|
|
22316 A/70 |
|
Current U.S.
Class: |
220/612; 220/662;
229/5.5 |
Current CPC
Class: |
B65D
75/008 (20130101); B65D 33/02 (20130101); B29C
45/14811 (20130101); B29K 2995/0067 (20130101); B29K
2715/006 (20130101); B29C 45/1418 (20130101) |
Current International
Class: |
B65D
33/02 (20060101); B65D 75/00 (20060101);
A45c () |
Field of
Search: |
;150/.5
;229/5.5,1.5R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wood, Jr.; M. Henson
Assistant Examiner: Culp, Jr.; Thomas C.
Claims
What is claimed is:
1. A semirigid container comprising:
a premolded bottom of plastic material having a contoured side
circumscribing a transverse wall, said side having at least one
flat outward extension, and a stop shoulder transverse to said
contoured side; and
a containing element of flexible material having at least one
surface of thermoplastic material and at least one longitudinal
weld joining together juxtaposed portions of said surface of
thermoplastic material, said containing element being welded to
said contoured side of said bottom with said extension being
interposed between said portions of said surface of thermoplastic
material and adjacent said longitudinal weld, whereby said
premolded bottom closes an end of said containing element.
2. The container as claimed in claim 1, wherein said containing
element comprises a single folded sheet of said flexible material,
and said longitudinal weld joins together the free ends of said
folded sheet.
3. The container as claimed in claim 1, wherein: said at least one
outward extension comprises a pair of outward extensions; said
containing element comprises a pair of sheets of said flexible
material; and said at least one longitudinal weld comprises a pair
of longitudinal welds joining together two opposing sides of said
pair of sheets.
4. The container as claimed in claim 1, wherein said contoured side
has a circular configuration.
5. The container as claimed in claim 1, wherein said contoured side
has an elliptical configuration.
6. The container as claimed in claim 1, wherein said contoured side
has a configuration formed of interconnected arcuate lines.
7. The container as claimed in claim 1, wherein said premolded
bottom includes bearing projections, whereby it is maintained at a
raised position from a supporting surface.
8. The container as claimed in claim 1, wherein at least one
surface of said transverse wall is covered with a sheet of material
making the transverse wall impermeable.
9. The container as claimed in claim 8, wherein said impermeable
sheet comprises at least one aluminum sheet adhesively joined to at
least one surface of said transverse wall.
10. The container as claimed in claim 8, wherein said at least one
surface of said transverse wall is an inner surface.
11. The container as claimed in claim 8, wherein said transverse
wall, said contoured side, and said stop shoulder are integrally
formed portions of said premolded bottom.
Description
This invention relates to a completely heat-welded, hermetically
sealable semirigid container.
It is the object of this invention to provide a container
prevailingly comprising flexible materials and rigid plastic
materials, suitable:
A. to contain liquid, semidense and dense, powdered and granule
products;
B. to retain a vacuum condition; and
C. depending on the materials comprising it, to stand also the high
temperatures required for the content sterilization.
More particularly, it is the object of the invention to provide a
completely heat-welded, semirigid hermetic container for containing
foodstuffs.
Completely heat-welded hermetic containers are known and wholly
formed of multi-layered flexible materials for containing
foodstuffs and which are in the form of envelopes. Such known
envelope containers suffer from the disadvantage of possibly having
microholes which might jeopardize the preservability of the
product. These possible microholes are due to localized
overstresses arising from stuffing as a result of a change in the
envelope shape which from flat becomes tridimensional.
The container according to the present invention overcomes the
disadvantages of the conventional solutions in that the shape being
taken after stuffing is consistent, that is a shape taken without
causing detrimental local stresses to the material comprising
it.
According to the invention the container is essentially
characterized by comprising a pre-shaped bottom of heat-weldable
thermoplastic material, as well as a top container portion, at
least partly formed of heat-weldable material consistent with that
of the bottom, formed of a preferably tubular element which at one
of its ends is heat-welded to the bottom and provided with a top
opening suitable to be closed by transverse heat-welding upon
completion of product stuffing.
Thus, a container is provided wherein the bottom and top portion
constitute a single unit without any solution of continuity, which
gives the desired tightness feature.
The bottom can be made of mouldable thermoplastic material, such as
polyethylene, and the tubular element can be made of any among a
wide range of conventional layered materials, wherein the inner
layer will comprise polyester (polyethylene terephtalate)
polypropilene, polyamides and similar thermoplastic material
consistent with that of the bottom, where by consistency it is
meant the possibility that such material adheres under thermal
action (with or without simultaneous pressing action) to the bottom
material. For example, where the bottom comprises polyethylene, the
inner layer of the layered material will comprise polyethylene,
while where the bottom is of polypropilene, the inner layer will
also be of polypropilene. The layers in the layered material may be
combined as follows: cellophane (cellulose leaf) polyethylene,
cellophane (cellulose leaf) aluminum-polyethylene,
polyester-polyethylene, polypropilene-polyethylene,
paper-polyethylene-thin board-polyethylene, thin
board-aluminum-polyethylene,
polypropilene-aluminum-polyester-polyethylene (or
polypropilene)-polyester (or polypropilene)-aluminum-polyester (or
polypropilene)polypropilene-polyester-aluminum-polyester,
polyester-aluminum-polyester (or polypropilene)-aluminum,
polypropilene, and so on.
These layered materials are commercially known and described in
many patent publications, whereby it is deemed unnecessary to
describe them in more detail.
According to a preferred embodiment of the invention, the container
portion comprises two flat sheets (or a single folded sheet)
heat-welded to each other along the longitudinal sides thereof.
This container portion is heat-welded along the lower contour to
the bottom which, in order to ensure a thorough tightness at the
longitudinal edges, has extensions interposed between the two
sheets (or between the folding and the opposing free ends in the
case of a folded sheet) at the area of the longitudinal edges, so
that by heat-welding said edges the material of these extensions
will at least partially be melted filling up the voids between the
edges of the sheet(s) and bottom, thus ensuring a perfect
tightness.
It has been found that, in case of low thicknesses or in case of
unaccuracies which may occur in mass-productions, the bottom wall
or the wall defining the container bottom may have some gas
permeability capable of damaging the product confined in the
container.
According to the invention, such a disadvantage is avoided by
providing that at least one of the surfaces of the wall defining
the container bottom is covered with a sheet of impervious material
attached to said one surface. The imperviousness material may be of
a composite nature, that is a layered material comprising at least
two layers, one of which is an aluminum foil (for example, 5-50
micron thick) and the other of which is a thermoplastic material
consistent with that of the bottom. Also in this case, by
consistency it is meant that the bottom material might remain
adhesively attached to the imperviousness material under thermal
action with or without a pressing action. Thus, for example, where
the bottom is made of polypropilene, the layer contacting the
impervious material bottom will also be made of polypropilene,
while where the bottom is made of polyethylene the adhesive layer
associated with aluminum will be also made of polyethylene.
The adhesive layer thicknesses are not critical and can be those
commonly used in the art of composite laminated materials for
making heat-weldable flexible containers. By way of example, the
thickness may range between 5 and 1,000 micron, while the annealed
aluminum thickness may range between 5 and 50 micron.
The application of the impermeabilizing sheet to the bottom can be
accomplished in several manners not forming part of the invention
as within the scope of conventional techniques. Thus, for example,
the impermeabilizing sheet, so shaped as to correspond to the area
to be impermeabilized, can be applied on the formed bottom to
remain adhering thereto, exerting a simultaneous heating and
pressure effect on the sheet. Another approach consists of
introducing the shaped element of impermeabilizing sheet into the
bottom moulding die, then injecting the bottom material into the
die. Due to heat and pressure, the sheet element adhesively joins
the bottom being moulded.
The invention will be better understood from the following detailed
description given by mere way of example, reference being had to
the accompanying drawings in which:
FIG. 1 is a partly sectional, side elevation view showing a first
embodiment of the semirigid container which is elliptic in
cross-section;
FIG. 2 is a bottom view of the container shown in FIG. 1;
FIG. 3 is a partly sectional, side elevation view showing a
different (circular) embodiment of the container;
FIG. 4 is a view similar to that of FIG. 3, but rotated by
90.degree. ;
FIG. 5 is an enlarged view the detail for the longitudinal weld of
the layered material forming the top or containing portion of the
container, as required for converting the web-like material into a
tube;
FIG. 6 is a diagrammatic side view of the container according to
the invention;
FIG. 7 is a sectional view taken on line VI--VI of FIG. 6, wherein
the walls are slightly spread apart;
FIG. 7a is a sectional view taken on line VII--VII;
FIG. 8 is an exploded view of a container, wherein the containing
portion is provided from two sheets which, however, can be
substituted for by a single sheet folded as shown in FIG. 8a;
FIG. 9 is a cross-section of the bottom alone;
FIG. 10 is a perspective view showing the corner detail of the
container, assumed that one of the sheets of the containing portion
has been raised;
FIG. 11 is a side view showing another embodiment of the
container;
FIG. 12 is a sectional view taken on line XII--XII in FIG. 11;
and
FIG. 13 is a perspective view showing the bottom following
application of the impermeabilizing sheet thereon.
As shown in FIGS. 1 and 2, the container comprises a bottom 1
provided by moulding thermoplastic material, such as polyethylene,
polypropilene or the like. This bottom comprises a substantially
flat raised central portion 2 connecting by a perimetral chamfer 3
with an edge 4 which is suitably slightly flared so as to
facilitate the piling of said bottoms.
The contour of edge 4 is characterized by an outward facing
perimetral flange 5, against which there abuts the lower end of a
tubular element 7 constituting the upper or containing portion of
the container.
As shown in FIG. 2, the bottom is of a substantially elliptic
shape, or however formed of curved sections which are
interconnected. Stiffening ribs 8 may be provided along the major
diameters of the bottom below the wall 2.
The tubular element 7 is formed of a sheet of composite material
comprising, for example, double, triple, quadruple or quintuplicate
layers: cellophane-polyethylene, cellophane-aluminum-polyethylene,
polyester-polyethylene, polypropilene-polyethylene,
paper-polyethylene, thin board-polyethylene, thin
board-aluminum-polyethylene, etc., as provided by composing the
individual base films and the like. The composite materials of the
above list providing an inner layer comprising polyethylene are for
use with a bottom 1 also made of polyethylene.
Generally, to accomplish heat-welding between the bottom 1 and
tubular element 7, it is required that the contacting materials
thereof are consistent and preferably the same. Where the bottom
comprises polypropilene, the layered material making up said
tubular element 7 will preferably have an inner layer of
polypropilene and may be formed of polypropilene and
polyester-aluminum-polypropilene, or
polyester-aluminum-polyester-polypropilene.
The lower end of the tubular element is heat-welded (that is
attached by exerting a pressure with a contribution of heat) to the
perimetral edge 4 of bottom 1. Heat-welding is accomplished by
exerting a pressing effect through heating jaws against the lower
end of the tubular element at the area of edge 4, this effect being
resisted by a resisting body inserted in the bore of the bottom and
mating therewith.
The tubular element 7 has a longitudinal weld 9 as formed from a
layered material sheet or web, the longitudinal edges of which are
superimposed to one another as shown in FIG. 5. This figure shows
how one of the longitudinal flat sheet edges is turned over at 11,
so that faces of the same material and thus heat-weldable to one
another are facing one another.
After introducing the product, the tubular element 7 is closed by
top transverse heat weld shown at 10.
A different preferred embodiment of the container is shown in FIGS.
3, 4 and 5. Similar or corresponding elements to those of the
embodiment in FIGS. 1 and 2 have been designated by using the same
reference numerals followed by a prime.
The bottom may have other forms than those shown and described,
such as a conical form or however identified by arcuate surfaces,
having a constant or varying radius of bending, such surfaces being
interconnected.
Referring to FIGS. 6-10, the container substantially comprises the
following elements: two flexible sheets 101 and 102 (or a folded
sheet 101a) and a bottom designated as a whole at 103.
The sheets 101, 102 or 101a can be made of the above mentioned
heat-weldable materials. The bottom, also made of one of the above
mentioned materials, is provided by moulding and includes a flat
raised portion 104 connecting through a possible chamfer to an edge
105 which can suitably be also slightly flared so as to facilitate
the piling of said bottoms.
The lower contour of edge 105 is characterized by an outward facing
continuous perimetral flange 106, the lower edge of the containing
portion comprising the sheets 101, 102 or the single sheet 101a
abutting there against.
The bottom shape substantially resembles a deformed ellipse at the
opposite ends where flat extensions 107 are provided.
At suitable locations on said flange 106, ribs 108 can be provided
for maintaining the container lifted from a rest plane to allow the
inner cavity of the bottom to be reached by the hot fluid as
required, for example for cooking and sterilizing the product
within the container.
The extensions 107 are interposed between the two sheets (as shown
in FIG. 10, particularly at the edges of the latter). The sheets
are moved near each other and then by welding bars (known and not
shown) two weld lines 110 and 111 are accomplished along the edges,
these weld lines also involving said extensions 107, which due to
heat partially melt and fill the voids at the junction of the two
sheets, ensuring a perfect tightness. By a second heat-welding
operation, accomplished by welding jaws mating the contour of edge
4, the lower end 112 of the sheets (already attached to the bottom
through the extensions 107) is welded to the edge 105 of said
bottom.
After having thus made the container, the latter is filled with
product and then its open inlet is closed by heat-welding along the
transverse area 113 defined by broken lines.
Thus, a container is provided and has shielded corners (because of
the two longitudinal welds 110 and 111), capable of
self-supporting. This feature has the advantage that in a
sterilizing chamber a larger amount of containers can be arranged,
since the containers need not to be laid down. The advantage is
also achieved for a more effective sterilization as all of the
container faces are completely free and, therefore, can be attacked
by the sterilizing fluid. The container may not require the use of
outer packings and is perfectly tight. Moreover, with respect to
the flexible envelope containers and under the same conditions as
to volume and containable material, it requires a less amount of
flexible material, which results in a lower cost of the material.
Finally, due to the consistency of the deformations and thus
because of absence of local overstresses no microholes will occur
in the flexible material making up the containing portion.
The container shown in FIG. 11, 12 and 13 is substantially the same
as that above described.
The container comprises a bottom, designated as a whole at 201, in
connection with which the expedients according to the present
invention have been devised. The container also comprises two
composite sheets, that is multi-layers which are heat welded to one
another along two longitudinal edges 204 and 205 so as to maintain
them joined to one another. The two sheets are also joined by
heat-welding to the contour edge 206 of the bottom 201 along the
zone indicated at 207. After filling up, the container is closed by
heat-welding transversely of the inlet area 208 identified by the
broken lines.
A possible disadvantage of this embodiment resides in that the top
surface or bottom 209 of the bottom may for any reason be pervious
to gasses, which could adversely affect the product within the
container, particularly where the contents are foodstuffs.
It is the object of the embodiment to impermeabilize this specific
surface 209 and according to the invention this is achieved by
applying thereon, or on the inner or outer side thereof, a shaped
impermeabilizing sheet to cover or to involve said surface 209 and
the next adjacent areas, so that gas is prevented from moving to or
away from the contents. In other terms, with its wall 209 and next
adjacent sections 210, the bottom 201 defines the inner space 211
containing the product. Thus, where the impermeabilizing sheet is
applied on the side facing the container space 211, this sheet, as
shown by broken lines in FIG. 12, shall involve not only the side
of zone 209 and the sections 210 next adjacent thereto, but also,
although to a limited extent such as a few millimeters (1-3 mm.),
the contour side 206 of the bottom. The impermeabilizing sheet can
arranged on the outer bottom side as well, as shown by dash and dot
lines, and its shape and extension should be such as to block up
the less long permeability paths for the gas. It is apparent that
the approach as shown by dash and dot lines is unfavorable, since
the gasses could move along the height of sides 6, even if this is
practically to be excluded due to the substantial length of this
path.
The impermeabilizing sheet is preferably formed of a two layer
material, one layer of which is aluminum having the task of
impermeabilization, and the other of which is thermoplastic
material consistent with that of the bottom and serving to provide
adhesion between aluminum and bottom. Consistency is to be intended
in that, under heat and possible pressure effect, the bottom
material and that of the adhesive layer would interpenetrate so as
to ensure a thorough connection for the impermeabilizing sheet to
the bottom.
By way of example, the bottom can be made of polypropilene or
polyethylene. In the former case, the adhesive layer will be made
of polypropilene, while in the latter case it will be made of
polyethylene.
Although only one embodiment of the invention has been described,
it will now be easy for those skilled in the art to devise many
changes and modifications, which however are all to be intended as
within the scope of the invention.
* * * * *