Note: Descriptions are shown in the official language in which they were submitted.
~O~Z7
This invention relates to improvements in or relating
to collapsible tubes for dispensine toothpaste, ~alves, creams
and the li~e and particularly to a collapsible tube of
ilexible plastics material.
~he replacement of the conventional tube oi lead, tin
and other ductile materials by a tube oi ile~ible plastics
material has been inhibited by the problem that aiter a
quantity oi the contained material has been ~queezed out the
- material at the tube outlet is suc~ed bac~ into the tube as
the squeezing pressare on the tube body is released. This
so-called "suck-bac~" problem gives rise to diiiiculties
both to the user and ior the contained material itseli due
to the entry oi air into the tube as it is emptied.
Conventionally collapsible tubes are sealed at o~e end
with a transverse ilat seal and are provided at the other end
with a circular head-having the circular portion secured
within the body oi the tube and an annular shoulder portion
tapering inwardly away irom the tube body to an outlet which
can be closed, for example, by a threaded cap. The
diameter oi the circular portion i~ o~ course one oi the
parameters determlning the volume oi the tube but this
circular portion als~-makes it diificult to expel the
last oi th'e''''contained material, particularly Nhen the
body is o~ flexible plastics material and cannot be
rolled up as can a-tube of~ductile material.
- It has been proposed to provide the tube with an
ellipb'ica~-he~,'that''~s''a_head'in~w~i'o~`'t'he ~irt
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~046027
portion which i~ secured to the tube body is elliptical.
This minimises the problem of expelling the last of the
contained material. ~uch an elliptical head when used
with a body o~ ~lexible plastics material gives however a
reduced volume for a given area of the ilexible plastics
material as compared to the use of a circular head because
oi the generally flattened cross-section of the tube body.
It i9 of course possible to fill such a tube having an
elliptical head under pressure to achieve a greater volume
of contained material but this is unacceptable to the user
since the contained material would be e~pelled by the
overpressure on opening the tube.
It is there~ore an object oi the present invention to
provide a collapsible tube oi fle~ible plastics material
which minimises both the problem o~ suck-back and that oi
squeezing out the entire contained material without unduly
reducing the contained volume.
According to the present invention there is provided a
collapsible tube having a tubular body portion oi flexible
plastics material closed at one end by a transverse ~lat
seam and provided at the other end with a--head having a
skirt portion secured within the body portion, the s~irt
portion having a major a~is aligned with the transverse flat
seam and a minor axis transverse thereto, a longitudinal
preformed crease line extending from each end oi the major
axis to the respective end~ oi the transverse ~lat seam and
a curved pre~ormed crease line on both sides oi each o~ the
longitudinal crease lines, the ends of the curved crease
1046~Z7
lines joining with respèctive longitudinal crease lines and the
curved crease lines defining at the location where they are
,spaced most distant ~rom their respective longitudinal
creases a rectangular transverse cross-section oi the iilled
body having an area greater than the transverse cross~
sectional area oi the body at the head.
The curved crease lines ln the tube according to the
present invention enable the tube body to be gradually
collapsed irom the iilled condition as the contained material
is squeezed out. This is because the curved lines deiine a
pre-determined filled shape oi the body and when the body is
squeezed irom this shape towards the empty or ilattened
condition the shape oi the body is determined by the
longitudinal crease lines and the shape and size oi
the head.
In the iilled condition the body portion oi the tube
takes up a shape deiined by the curved crease lines, the
body wall between each oi the two curved lines which join
one oi the longitudinal crease line9 when viewed in a transverse
plane being a substantially straight line. As the contained
material i9 reduced this substantially straight line becomes
a "V" shaped line having one-of the longitudinal creases at its
ape~ the longitudinal crease lines at each side of the tube
progrëssively moving outwards reducing the included angle oi
the "V" as the quantity of contained material reduces. The
curved crease lines allow this ilattening of the body to take
.. , _ _ .. . .
~place irom the flat seam at the base of the tube progressively
towards the head.
10466)27
In that the head is not circular in cross-section
where it fits the body portion squeezing out of the last of
the contained materia'l i9 fa.,cilitated since the free state
oi the empty tube is inherently more flattened that if the
head was circular, .Nevertheless the voIume'~of the tube
in the full condition, and in which the contained material
i9 not sub~ect to pressure ~rom the tube tending to collapse,
is increased ~or a given area oi body material by reason
that the body portion has a maximum cross-sectional area
greater than that o~ the head.
The curved crease lines are preferably arranged
symmetrically about the longitudinal crease lines and
advantageously ~oin the longitudinal crease lines at the
intersection o~ the latter with the transverse ~lat seam at
one end o~ the body and at the intersection with the innermost
edge of the skirt portion o~ the head a~ the other end o~.
the body.
In order that the tube has a magimum volume the ma~imum
distance that the curved crease lines are spaced from the
respective longitudinal crease lines is such that the maximum
transverse cross-section is a square.
The invention will now be more particularly described
with re~erence to the accompanying diagrammatic drawings
in which
Figure 1 shows a ~ront view of a collapsible tube
in the fully filled condition;
Figure 2 shows a side view of the tube o~ Figure l;
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10466~27
Figure 3 shows a plan view from above oi the
tube oi Figure l;
Figure 4 shows a transverse cross-section along the
line IV-IV of Figure 2;
Figure 5 shows the tube oi Figure 1 in a partially
empty condition;
Figure 6 shows a cross-sectional elevation o~ the
tube oi Figure 5 similar to Figure 4; and
Figure 7 shows the side view of the tube o~
Figure 1 almost empty.
Reierring to Figures 1 to 4 there is shown a collapsible
tube having a body portion 1 o~ polypropylene iilm 300 micron
thic~ and an injection moulded head 2 oi' plastics material.
The head has a skirt portion 3 which is securèd within the
body portion 1, the body portion abutting with a shoulder 4
de~ining one end o~ the skirt. The skirt has an oblong shape
having a ma~or axis 5 and a minor axis 6 with a curved proiile
extending symmetrically about the ma~or axis. The
intersections oi the curved proiile with the ma~or axis are
substantially points at 7.
From the shoulder 4 the head has an inwardl~ sloping
shoulder portion 8 terminating in an outlet 9 threaded at
10 to receive a closure cap (not shown). The length oi the
minor axis 6 o~ the skirt is determined primarily by the
size oi the outlet and the closure cap, the length oi the
minor axis being ~ept as small as practical.
The body portion is closed at the end opposite the head
by a transverse flat seam 11 parallel with the major axis of
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1046~)27
the head. From each end oi the flat seam longitudinal
pre-~ormed crease lines 12 extend the length of the body
portion to the ends 7 of the major axis oi the head.
From positions 14 just below the innermost edge 13 oi the
skirt portion of the head 4 curved pre~ormed crease lines
15 extend ~rom the longitudinal crease lines, two curved crease
lines being associated with each longitudinal crease line.
The curved Grease lines 15 are symmetrical about their
respective longitudinal crease lines and curve away from the
longitudinal crease lines towards the mid point of the body
lenEth and then curve back to meet the intersection of the
respective longitudinal crease lines with the trans~erse flat
seam thereby deiining with the longitudinal crease lines body
side wall portions 16 and 17. The ma~imum
distance 18 which the curved lines are spaced irom the
longitudinal crease lines lies substantially mid-way along
the body and is greater than one half oi the minor axis 6
oi skirt 3 so that at the mid position oi a iilled tube the
transverse cross-section as shown in Figure 4 is a rectangle
having an area greater that the area oi the skirt.
In the iilled condition as shown in Figures 1 to 4 the
shape oi the body portion is determined by the curved crease
lines 15. Side wall portions 16 and 17 between the two
curved crease lines associ~ted with one longitudinal crease line
are substantially aligned with one another as shown in Figure 4
and in this condition the tube is stable 90 that it can contain
material without the contained material being under pressure.
As the tube i9 squeezed to e~pel the contained material
the side wall portions 16 and 17 collapse outwardly to a "V"
shape having the longitudinal crease line 12 at the apex of
the "V" as shown in Figures S and 6. In this partially
empty condition there is no tendency o~ the body to revert
to the shape of a fully filled container. Moreover, after
the side wall portions 17 and 18 together form a "V" shape
the preiormed crease lines tend to urge the body of the
tube gently towards the ~lattened condition. This minimises
any tendency towards "suck-back".
As the tube is further emptied the body takes up a shape
shown in Figure 7. The natural tendency oi the tube when
_
empty is to take up a tapered shape having its widest part
determined by the minor a~is of the head~and tapering ~rom
lS the head ~toward9 the transverse ~lat seam. Thus in the
extreme case that the minor axis of the -head was nil the
natural shape oi the tube when ~mpty would be flat with no
contained colume. The minor axis of the head i9 therefore
kept as small as possible and it has been found in practice
that the natural stickiness of remaining traces oi the
contained material keep the body walls together in the empty
part of the tube as shown at 19 in Figure 7. This stickiness
is sufficient to maintain material in the outlet and thus
prevent air being sucked back into the tube, the remaining
contained material ~taying at the top of the tube. The
generally flattened transverse cross-sectional shape of the
head allows substantially all the contained material to
~04SO;~
be squeezed out and generally as~ists in keeping the body
oi the tube in the ~lattened state to which it has been
squeezed.
It will oi course also be appreciated that because the
sum oi the magimum lengths 18 of the side wall portions 16
and 17 associated with one oi the longitudinal orëase lines
is greater than the length of the minor agis of the head
the volume of the tube in the stable filled condition i9
greater than ii the curved lines were not present. The
maximum volume Or the tube i9 achieved when the maximum
length 18 Qf-~ach- of the side wall portions 16 and 1~ is equal
to ~th oi the transverse peripheral length of the body
90 that the cross-section of maximum area is a square.
Without the curved lines the tube would have only`~one stable
shape, i.e. tapered from the hea~-to the transverse flat
seam ~imilar to that of the tube oi the present invention
when empty. Such a tube could of course be filled under
pressure with a greater volume oi contained material but
would result in a large amount of the material being
e~pelled as soon as the closure cap was removed. When
the contained material is only used in small quantities at
any one time e.g. tooth paste, thi~ is most undesirable.
The body portion of the tube can be made from a flat
sheet of the fle~ible plastics m~terial and the preformed
crease lines formed by upsetting the material in any
conventional manner. The sheet of material can then be
folded along the two longitudinal crease lines and
joined by a longitudinal seam (not shown) to form a tube.
~046~Z7
Whilst the described embodiment of the invention has
curved crease lines extending-''symmetrical`ly substantially
the entire length o~ the body portion of the tube it will
be clear that other coniigurations of the curved crease
lines can be adopted which provide a tube having a stable
condition in the filled condition and having a volume in
exces~ oi the volume of a filled tube in the stable
condit'ion utilising the same area oi~ material ~or the
body portion but without the curved crease lines.
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