Note: Descriptions are shown in the official language in which they were submitted.
CA 02237933 1998-OS-15
WO 97/19005 PCT/GB96/02811
1
Infusion packet and its manufacture
This invention relates to packets containing
infusion material, such as tea or coffee, and provided with
a drawstring or thread for contracting the package to
extract moisture after infusion.
Such squeezable packets have only been used on a
small scale. Many of the forms of bag proposed are
inefficient or unreliable, eg. allowing leakage of the
material before use or rupturing too easily when squeezing
IO pressure is applied. Others have not been able to be
produced economically and yet others have been inconvenient
to use or unattractive.
It would be desirable, therefore, to provide a
packet which can, at least for the greater part, be
produced in a conventional manner, and with which a
drawstring or thread can be combined relatively simply and
in a way which gives a good degree of reliability in use.
The present invention provides, in accordance
with one of its aspects, a method of producing a packet
comprising a pair of sealed compartments containing doses
of infusion material and joined together at opposite ends
of the packet, a drawstring between the two compartments,
the compartments being initially arranged end to end joined
by a connecting region at one end of the packet, an
intermediate portion of the length of the drawstring being
attached to the connecting region before the compartments
are doubled over to bring their ends remote from the
CA 02237933 1998-05-15
WO 97/19005 PCT/GB96/02811
2
connecting region together at the other end of the packet
with pull portions of said drawstring extending from said
intermediate portion and running between the compartments
to said other end of the packet, the compartments being
secured together at said other end in a manner which
permits movement of said pull portions of the drawstring to
contract the packet by drawing the opposite ends towards
each other.
Preferably, the respective pull portions of.the
drawstring are detachably secured to each of the
compartments intermediate the length of the respective
compartment before the compartments are doubled over.
The pull portions can conveniently have ends
projecting from said other end of the packet which, when
said remote ends of the compartments are brought together,
are attached to respective external tag means to make
manipulation of the drawstring easier.
According to another aspect of the invention,
there is provided an infusion packet comprising a pair of
sealed compartments containing infusion material and joined
together at opposite ends of the packet, and a drawstring
secured by a portion intermediate its length to a
connecting region between the two compartments at one of
said ends, the drawstring comprising pull portions
extending between the compartments from said secured
portion to said other end of the packet to be movably held
at said other end, whereby said pull portions can be
tensioned to contract the packet.
CA 02237933 1998-OS-15
WO 97/19005 PCTlGB96/02811
3
The drawstring is conveniently fixed by sealing
means to an inner;face of said end connecting region,
preferably at a location that does not coincide with the
walls forming the compartments. Preferably the drawstring
is so secured to said region that it spans substantially
the full width of the compartments at said one end. The
pull portions between the compartments are preferably so
arranged that they continue from a respective laterally
offset region of said end connecting region to an
oppositely offset region at the other end of the packet.
It may be arranged that, prior to use of the
packet, the pull portions at said other end of the packet
are fixed to a margin of the packet and/or pull tag means
secured to the packet, said margin and/or pull tag means
being releasable from the packet to allow the pull portions
to be drawn out of said other end to contract the packet.
In a preferred form of the invention, each pull
portion has an excess length, that is to say a length
greater than the shortest drawstring path between the
opposite ends of the packet, retained between said two ends
of the packet by releasable attachment to the compartment
walls. By retaining these additional lengths of drawstring
between the compartments the packet can be made more
convenient to use. It may be preferred to gather the
excess lengths at least mainly adjacent said other end of
the packet. Conveniently, the excess lengths are attached
to their respective compartments in a serpentine pattern
that may extend substantially across the width of each
CA 02237933 1998-05-15
WO 97/19005 PCT/GB96/02811
4
compartment.
In a further preferred feature, the compartments
are so connected. together at said other end of the packet
as to leave free channels between them in which the
drawstring pull portions are held captive but are freely
slidable.
By way of example, the invention will be further
described with reference to the accompanying drawings, in
which:
Fig. la to ld show a series of steps in the
formation of an infusion packet according to the invention,
Fig. 2 shows the packet produced by the method
illustrated in Fig. 1,
Fig. 3 illustrates a pair of compartments forming
a second infusion packet according to the invention, with
its drawstring, in an intermediate stage of the manufacture
of the packet,
Figs. 4 and 5 are mutually transverse views of a
later stage of the manufacture of the second packet,
Fig. 6 illustrates the completed packet,
Fig. 7 shows another pattern of thread as an
alternative to the pattern shown in Fig. 3,
Fig. 8 illustrates a modification of the packet
in Fig. 5,
Fig. 9 illustrates the packet of Fig. 8 after the
excess thread has been drawn out from between the
compartments, and
Fig. 10 illustrates a further alternative pattern
CA 02237933 1998-OS-15
WO 97/19005 PCT/GB96/02811
of thread, in an analogous manner to Fig. 7.
Figs. la to 1d illustrate a series of process
steps that can be carried out on a continuous web of heat-
sealable material to form a packet envelope as the web
5 moves through successive operating stations. In a first
station shown in Fig. la, doses of infusion material 2 are
deposited on the initially flat web 4. The side margins of
the web are then folded over and heat-sealed together with
a longitudinal seal 6 to form a flat tube which contains
the doses (Fig. lb). Transverse strip-form seals 8,10 are
next made at intervals to seal the individual doses into
separate compartments 12a,12b (Fig. lc). Although not
necessarily separated from the continuous web at this
stage, the body of each packet resulting from these steps
comprises a pair of compartments 12 end to end, joined
together at one end of the packet by the sealing strip 8
and closed at the other end~of the packet by the rather
narrower sealing strips 10.
A looped thread of a drawstring 14 is now placed
onto one compartment 12a of the pair. The loop may be
formed onto the web material or it can be transferred to it
after being preformed. An intermediate portion 16 of the
loop is located on the connecting region formed by the seal
strip 8 (Fig. ld) and the ends 18 of the drawstring extend
over the seal strip 10 at the opposite end of the
compartment. The projecting ends 18 are held in a tag 20.
The thread is permanently secured to the seal strip 8 and
to the tag 20, eg. by heat sealing. It is also releasably
CA 02237933 1998-OS-15
WO 97/19005 PCT/GB96/02811
6
attached to the compartment wall, eg. by tacking heat welds
(not shown) at intervals along the convoluted pattern in
which it lies on that wall.
The pair of compartments 12a,12b are then doubled
over to bring them face to face, the separation of the
pairs of compartments normally having been completed by
this stage, and enclose the drawstring thread loop between
them. The seal strip 8 is folded along its length to shape
a V-form connecting region projecting inwardly between the
compartments. The free ends of the compartments are heat-
sealed together at their sealed edges 10 but unsealed
passages are left where the thread ends run between those
edges.
There is thus formed the packet of Fig. 2 in
which the two compartments 12,12b are secured together at
their opposite ends, by the seal strip 8 of the V-form
connecting region and by end seal 22. The drawstring is
permanently secured to the connecting region at the bottom
of the packet, which meanwhile has been given the re-
entrant V-fold, but the major part of the drawstring is
releasably held in place against a wall of one compartment.
The projecting ends 18 of the drawstring are trapped but
are slidable in the end seal 22 at the top of the packet
from where they project to be secured to the tag 20.
When the packet is to be used, by pulling the tag
20 the tack welds between the thread loop and the wall of
the compartment 12a can be released and the surplus length
of the thread loop can be loosely drawn out from the space
CA 02237933 2005-03-18
7
between the compartments. The packet can then be infused while
the tag remains dry, outside the liquid. After infusion, the
tag is separated into two parts by tearing through its central
perforations. By then pulling the drawstring ends 18 away from
each other the free lengths of thread form pull portions that
draw the top and bottom of the compartments together,
contracting the bag and squeezing liquid from the compartments.
The manner in which the drawstring loop runs substantially from
the two ends of the connecting seal strip to diagonally
opposite, widely spaced locations at the top of the packet
spreads the squeezing action on the infused material.
In Fig. 3 a flattened tubular web of envelope material
from which the packet is formed is shown divided into two
separate compartments 32a,32b by a pair of similar transverse
heat seals 34a,34b forming a central connecting region 36, and
the compartments being closed at their remote, other ends by
further transverse seals 38a,38b. Each compartment contains a
dose of infusible material (not shown) which is inserted before
it is sealed closed.
A drawstring 40 is laid onto the pair of compartments
in a pattern comprising a first entry run 42 of the thread
passing longitudinally of the web over the end transverse
seal 38a near one side edge 44a of the compartments, a
convoluted run 46 comprising two serpentine folds partly
overlapping that end seal and extending nearly the full
width of the tubular web. The convoluted run 46 terminates
near the opposite side edge 44b to the entry run
CA 02237933 1998-OS-15
WO 97/19005 PCT/GB96/02811
8
42, and the thread layout continues in a straight run 48
along the compartment extending close to that opposite side
edge 44b to the,.connecting region 36. The thread then
passes in a transverse run 50 over the centre of the
connecting region 36 extending across almost the full
lateral extent of the tubular web and the pattern is
repeated in an inverted form on the other of the two
compartments, the corresponding runs of thread being
designated by the same reference numbers with the added
suffix "a".
The thread is attached to the web, conveniently
by heat sealing (although as in all the examples an
adhesive may be used instead), with a permanent bond of the
transverse run 50 in the connecting region and with weaker,
detachable bonds of the other runs, sufficient to retain
the thread in the pattern in which it has been laid, but
able to be released to allow these parts of the drawstring
to act as a pair of pull portions in use. The attachments
of the convoluted runs 46,46a can be confined entirely to
the regions of the end seals 38a,38b to ensure that there
is no risk of rupturing the compartment walls.
Preferably, a continuous tubular web is formed
with a series of transverse heat seals in a continuous
dosing and sealing process as described in the first
example, the pairs of compartments being thereby formed as
a continuous series joined end to end and being separated
at a later stage. The drawstring can be laid in a
continuous length onto the web while the pairs of
CA 02237933 1998-05-15
WO 97/19005 PCT/GB96/02811
9
compartments remain joined together. It may be noted that
although the drawstring pattern will run in a continuous
manner along successive pairs of compartments, in each
succeeding pair of compartments it will be laid in a mirror
image to the pattern in the preceding pair of compartments.
Each pair of compartments is separated from the
continuous web length after the drawstring has been
attached to them in the pattern described. The pair of
compartments are then folded together about their
connecting region to bring their mutually remote ends
together. These ends are secured together by a
superimposed seal over their endmost regions, that is to
say, as far as a boundary 52. The convoluted runs 46,46a
are left clear of the end seal and the portions of the
thread running past said endmost regions of the
compartments are held in a manner which still allows them
to be drawn out in the direction of the illustrated sealing
crimps 54. In the course of the folding step, the
connecting region 36 has been folded inwards with the
transverse seals 34a,34b forming an inverted-V (shown in
Fig. 2) between the main bodies of the compartments. The
transverse thread run 50 lies at the apex of the V.
A folded tag card 58, preferably having a heat
sealing coating on its inner faces, is brought over the
joined ends, partly overlapping the end seal, and the card
is heat-sealed in place. Transverse lines of weakening 56
are then formed in the end seal regions, coincident with
the edge of the tag card substantially in the middle of the
CA 02237933 1998-05-15
WO 97/19005 PCT/GB96/02811
width of the seal. In sealing of the folded tag card in
place, the entry runs of the drawstring are permanently
secured between.the web walls where they are overlapped by
the tag card. Manufacture of the packet is now complete,
5 although for packaging the tag card may be folded over as
shown in Fig. 6, to make the packet more compact.
It will be understood without further
illustration that the folded tag card 58 can be replaced by
a flat tag card attached to one side of the joined ends of
10 the packet.
When the packet is to be used, the tag card 58 is
torn from the main body of the packet along the line of
weakening 56, but it remains attached to the main body by
the two entry runs 42,42a of the thread held movably in the
remaining portion of the end seal between the line of
weakening and the boundary 52. The card has a central line
of weakening 60 allowing it ~to be separated into two tags,
each attached to one of the entry runs. By then drawing
the two tags apart the detachable bonds of the convoluted
runs 46,46a can be ruptured and that part of the drawstring
can be drawn out from between the compartments. The packet
can now be infused, with the twa tags hanging free of the
liquid which the packet is immersed.
When infusion is complete, the tags can be drawn
further apart, the straight runs 48,48a now being pulled
through the end seal to contract the packet and so squeeze
out excess moisture. To make the bag easier to use, it can
be arranged that the straight runs 48,48a are attached by
CA 02237933 1998-OS-15
WO 97/19005 PCT/GB96/02811
11
seals that have a greater resistance to rupture than the
convoluted runs 46,46a, so that the user senses this when
he first pulls out the excess length of thread and more
easily avoids contracting the packet before infusion.
Fig. 7 shows an alternative layout of the
drawstring thread that can be used, for example, in the
packet of Fig. 3. The excess thread is accommodated in
zig-zag patterns 70,70a that extend from the central run 50
over the length and width of the packet rather than only
the width as in Fig. 3.
The packet of Figs. 8 and 9 is generally similar
to that shown in Figs. 4-6 and corresponding parts are
indicated by the same reference numbers. The ends seals
joining the two compartments together are now formed so as
to leave open channels 62 through which the entry runs
42,42a pass, so making it easier to draw out the thread.
Fig. 9 illustrates the bag at the stage at which the excess
thread has been drawn out from between the compartments, in
preparation for immersing the bag to infuse its contents,
but before the two tags have been separated and used to
pull the drawstring and contract the packet.
Fig. 10 shows a further alternative layout of the
drawstring 14 that can be used in the packets described
above, eg. the packet of Fig. 3. As in that earlier
example excess thread is arranged in two convoluted runs
80,80a which can be disposed remote from the central run
50, in the regions of the end seals of the tubular web (not
shown) similarly to the runs 46,46a of Fig. 3. In each run
CA 02237933 1998-OS-15
WO 97/19005 PCT/GB96/02811
12
80,e0a the thread is looped across the width of the web in
three passes as in the runs 46,46a of Fig. 3, but now
overlapping.
fn the examples described, the methods of
formation of the sealed compartments from the web material
can be conventional and may be performed with existing
apparatus. The formation of the thread loops and their
addition to the packets can be incorporated relatively
simply in this proceBa.
The method of the invention allows any desired
length of drawstring thread to be provided in a packet in a
manner that is secure, and in particular that minimises the
risk of leaving thread hanging freely where packets might
become entangled. It ie possible to have a wide choice for
the configuration of the thread loop without affecting the
construction of the packet compartments themselves.
It is also notable that because the drawstring is
held externally of the compartments themselves, it will not
compromise the sealed containment of the infusible
materials they carry.
Another feature of the illustrated examples is
that the attachment of the thread need not weaken the
packet and in particular the thread is not permanently
attached to a compartment wall where the tension applied
through the thread might rupture a compartment and allow
its solid contents to escape.
