Note: Descriptions are shown in the official language in which they were submitted.
CA 02269124 1999-04-27
Method and Ap~~aratus for Refillable Stick Dispenser
This invention relates to a method for refilling a stick which releases
product by application to a surface and which consists of
- a holder with a solid base and an opening at one end into which a stick
rotatable about its longitudinal axis is fitted, the stick which extends over
the
entire longitudinal axis of the holder being formed by a screwthreaded spindle
beyond one side of the base and by a hand-operated knurled nut beyond the
other side of the base outside the holder, and of
- a feed element which is non-rotatably mounted in the holder, being
designed for displacement longitudinally of the holder by means of the
screwthreaded spindle engaging in a screwthreaded bore extending
throughout the feed element to apply a product mass accommodated in the
holder and optionally of
- a closure cap designed to be pushed on over the upper edge of the
holder,
in which method for refilling the stick a moulding of the product mass adapted
to the internal volume - designed to accommodate the product mass - and
internal configuration of the holder and optionally formed with a bore,
preferably a blind hole, concentrically to the longitudinal axis is inserted
into
the holder from the opening at the end thereof.
The invention also relates to a refill cartridge for a stick which releases
product by application to a surface and which comprises
- a holder with a solid base and an opening at one end into which a stick
rotatable about its longitudinal axis is fitted, the stick which extends over
the
entire longitudinal axis of the holder being formed by a screwthreaded spindle
beyond one side of the base and by a hand-operated knurled nut beyond the
other side of the base outside the holder, and
- a feed element which is non-rotatably mounted in the holder, being
CA 02269124 2000-07-26
2
designed for displacement longitudinally of the holder by means of the
screwthreaded spindle engaging in a screwthreaded bore extending
throughout the feed element to apply a product mass accommodated in the
holder, and optionally
- a closure cap designed to be pushed on over the upper edge of the
holder,
the refill cartridge comprising a moulding of the product mass adapted to the
free internal volume - designed to accommodate the product mass - and
internal configuration of the holder and optionally formed with a bore,
preferably a blind hole, concentrically to the longitudinal axis.
There are already various known sticks which release product by
application to a surface, such as deodorant, adhesive, lipstick, release
agent,
shaving soap or colouring sticks, comprising a holder which is optionally de-
signed for closure by a cap, has an opening at at least one end' and
comprises a plunger designed for axial displacement over the length of the
holder to apply a preferably spreadable product mass accommodated in the
holder. These known sticks have the disadvantage that they are generally
not refillable.
For example, the adhesive sticks known from the prior art have to be
discarded after the adhesive has been used up or has dried out although, in
general, the adhesive stick mechanism is still in perfect working order after
the original adhesive filling has been used up. Accordingly, known sticks and
adhesive sticks, as plastic waste, are a significant source of environmental
pollution. In addition, new material (plastic) always has to be used in the
production of a new stick which, besides the production costs, adversely
affects the manufacturing price. Finally, the consumer is also forced to buy
a completely new stick every time.
A process of the type mentioned at the beginning for refilling a stick
which releases product by application to a surface and a refill cartridge of
the
type mentioned at the beginning are known from GB-A-246,657. This
CA 02269124 1999-04-27
' 3
document discloses a shaving soap dispenser from which the shaving soap
is dispensed by a spindle-driven disc and which is designed to be refilled
with
a stick of shaving soap formed with a blind bore. To refill the dispenser, the
stick of shaving soap with the blind bore is pushed via the spindle into the
housing of the dispenser. This method of refilling is not suitable for
adhesive
sticks comprising a moulding of spreadable, soft and plastic adhesive mass,
because when the product is pushed in - which is done by hand - it is in
danger of being deformed or even breaking so that it can no longer be
introduced cleanly and exactly in the stick holder.
In addition, processes for filling lipsticks and corresponding refill
cartridges are known from DE-B-1 003 411, FR-A-1 205 370 and US-A-
2,753,991. In these cases, the refill of lipstick mass is provided at one end
with a plunger or holder, the lipstick mass otherwise being surrounded by a
tube. To refill a lipstick, the plunger or holder at the end of the refill is
inserted into a lipstick mechanism accommodated in a stick tube, after which
the moulding is drawn with the plunger into the tube of the lipstick, the tube
sun-ounding the moulding of lipstick mass - supported by the front edge of the
lipstick tube - detaching itself frorn the moulding of lipstick mass. Refill
cartridges such as these are unsuitable for refilling known adhesive sticks
with a screwthreaded spindle because on the one hand they disclose a cup-
like plunger with a solid base, into which the screwthreaded spindle of known
adhesive sticks cannot be inserted, and because adhesive sticks such as
these do not have a feed mechanism which is designed to be lowered into the
stick tube and into which the plunger or holder at the end of the refill can
be
introduced.
The problem addressed by the present invention was to enable an
adhesive stick comprising a screwthreaded spindle to be refilled with product
mass.
In a refilling method of the type mentioned at the beginning, the
solution to the problem stated above as provided by the invention is
CA 02269124 1999-04-27
characterized in that the feed element is a cup-shaped plunger and the
product mass is a spreadable, soft and plastic adhesive and in that in that,
to
refill the stick, the plunger of the stick is first removed from the product-
free
holder, after which a tube which surrounds a plunger at its upper edge and
is connected at that end to a sleeve which encircles the plunger at a distance
and of which the internal diameter is such that the sleeve can be pushed on
over the upper part of the outer surface of the holder and has an inner
annular stop surface for the front end of the holder, is fitted with the
moulding
with the plunger at one end onto the tube and, by rotation of the knurled nut,
the plunger is drawn with the moulding into the holder up to the base thereof,
the tube being completely withdrawn and finally removed from the moulding
with the sleeve.
In a refill cartridge of the type mentioned at the beginning, the solution
provided by the invention to the problem stated above is characterized in that
the feed element is a cup-shaped plunger and the product mass is a
spreadable, soft and plastic adhesive and in that the moulding with the
plunger at one end is disposed in a tube which surrounds the upper edge of
the plunger and which is connected at that end to a sleeve which encircles
the plunger at a distance, the internal diameter of the sleeve being such that
the sleeve can be pushed on over the upper part of the outer surface of the
holder and has an annular stop surface for the front end of the holder.
Not only does this provide for safe fixing of the refill cartridge on the
stick holder, it also - and above all - guarantees centering of the tube of
the
refill cartridge and the holder. The wall thicknesses of the holder and tube
no
longer have to be exactly adapted to one another.
According to another aspect of the invention, the dimensions of the
sleeve are preferably such that the free end of the sleeve is level with, or
projects slightly beyond, the base of the plunger. Looking in the axial
direction, a sufficiently long annular space is thus created between the inner
surface of the sleeve and the outer surface of the plunger.
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In a first embodiment, the sleeve and the tube are made in one piece,
more particularly by injection moulding, the cross-section then being widened
radially at the junction between the tube and the sleeve to create an annular
stop surface for the front of the cylinder.
Alternatively, however, the tube and the sleeve may be made in two
parts joined together by a preferably annular snap-in connection.
In another embodiment of the invention, the plunger and the sleeve are
joined to one another by several bridges which break when the plunger is
drawn towards the base of the holder, i.e. act as artificially weakened
points.
In this embodiment, the plunger and the sleeve may be made as a one-piece
injection moulding, optionally together with the tube. Alternatively, the
plunger and the sleeve may be joined together by a drop-in or snap-in
connection designed to break when the plunger is drawn towards the base of
the holder, for example by forming small drop-in noses or hooks or the like in
the injection moulding process. These connections also separate from the
sleeve after insertion of the screwthreaded spindle during the refill process.
Accordingly, the invention starts out from the basic concept of
providing the user of a stick of the above-mentioned type with a moulding of
the particular spreadable product mass which is adapted to the internal
volume - designed to accommodate the product mass - and internal
configuration of the holder and which the user can draw into the holder of the
stick from the opening at its end. After the original product filling has been
used up, the consumer is thus able to refill the stick. The consumer no
longer has to buy a complete new stick. Because the key, non-consumable
parts of a stick are reused, the amount of waste, typically plastic waste
(because the sticks are normally made of plastic), is reduced. The
consumption of plastic is also reduced because the manufacturer no longer
has to market each product filling together with a stick containing the entire
stick mechanism.
In one embodiment of the invention, refilling of the stick is facilitated
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6
by the fact that a tube with a moulding of the spreadable product mass
accommodated therein and adapted to the internal volume - designed to
accommodate the product mass - and internal configuration of the holder is
fitted onto the holder and the moulding is drawn into the holder. This
prevents the product mass, which is soft and plastic, particularly in the case
of adhesive sticks, from being locally stripped at the front edge of the stick
holder during refilling so that the stick is not soiled.
In another embodiment of the invention, convenient refilling without
stripping of a soft and plastic mass during introduction of the moulding into
the stick can also be obtained if the moulding is provided with a plunger. To
this end, the plunger of the stick is first removed from the product-free
holder,
after which the moulding of the spreadable product mass with a plunger at
one end is drawn into the holder at the plunger end.
The moulding may be formed with a bore, preferably a blind hole,
concentrically to its longitudinal axis. Because a moulding formed with a bore
or blind hole is introduced into the holder during refilling, little, if any,
product
mass has to be displaced by the screwthreaded spindle during introduction
of the moulding so that no volume into which the product mass could escape
has to be provided in the stick or rather the holder for this purpose. In
addition, no surplus volume of product mass escapes from the stick so that
the stick is not soiled.
To enable the moulding to be readily inserted into the holder, a central
blind hole for the screwthreaded spindle may be provided along the axis of
the moulding. This embodiment enables the holder and the tube to have the
same internal diameter. If no central blind hole is provided for the
scxewthreaded spindle, the internal diameter of the tube should be smaller in
accordance with the increase in the diameter of the moulding brought about
by the cutting screwthreaded spindle.
Instead of a blind hole; it is of course also possible to provide a bore
extending over the entire longitudinal axis of the moulding.
CA 02269124 1999-04-27
7
To enable a stick with a screwthreaded spindle to be conveniently and
advantageously refilled, i.e. with no risk of soiling, another embodiment of
the
invention is characterized in that a tube with a moulding disposed therein is
fitted onto the holder and the moulding is drawn into the holder.
The plunger of the stick is first removed from the product-free holder,
after which the moulding of the spreadable product mass comprising the
plunger with a screwthreaded bore at one end is fitted at the plunger end onto
the screwthreaded spindle and, by actuation of the knurled nut, the plunger
is drawn with the product mass up to the base of the holder.
Particularly convenient refilling of the stick is possible when the
moulding is surrounded by a tube and provided at one end with a plunger.
To this end, another embodiment of the invention is characterized in that the
plunger is introduced into the holder surrounded by the tube at its upper edge
and, when the product mass is drawn into the holder, the tube is completely
pushed off or pulled off the plunger and the moulding and, finally, is
removed.
Basically, the spreadable product mass is filled into a tubular holder of
which
the base is formed by the plunger in such a way that the outer surface of the
plunger is surrounded by the holder at its upper end. Now, if for example the
scxewthreaded bore of the plunger is screwed onto the screwthreaded spindle
and if the plunger together with the product mass is drawn up to the base of
the holder by rotation of the knurled nut, the tube is continuously withdrawn
from the moulding at the same time so that, finally, it can be removed. The
dimensions of the tube are advantageously such that, as the plunger is
screwed down, the front end of the tube impinges on the opposite end of the
holder wall.
To facilitate insertion of the refill cartridge into the stick holder, another
embodiment of the invention is characterized in that, at its end, the moulding
comprises a plunger formed throughout with a central screwthreaded bore.
To prevent the product mass from drying out on the side facing the
plunger, the screwthreaded bore may be closed by a (thin) membrane
CA 02269124 1999-04-27
8
designed to be pierced by the screwthreaded spindle. In another preferred
embodiment of the invention, the screwthreaded bore of the plunger has a
single or multiple screwthread.
In the same way as all the other parts, the screwthreaded spindle of
the stick is made of inexpensive plastic, optionally having a certain
flexibility.
To facilitate introduction of the spindle end into the screwthreaded bore of
the
plunger of the refill cartridge, the base of the plunger is formed internally
with
a cone as an insertion aid.
The tube may also be closed at that end opposite the plunger to
prevent the product mass from drying out. For example, it is possible in this
embodiment to prefabricate the tube in the form of a cup and to fill this
prefabricated cup with product mass before it is closed by the plunger on the
open side of the cup.
So far as the dimensions of the tube are concerned, the only crucial
factor is the internal diameter adapted to that of the holder. By contrast,
the
wall thickness of the tube may basically be selected as required, although to
save material it should be at most equal to the wall thickness of the holder.
Similarly, the tube may basically be made of any material providing it
remains rigid during withdrawal of the moulding of preferably spreadable
product mass. The tube is preferably made of plastic or paperboard which
may be coated. By contrast, the plunger should preferably consist of plastic.
To facilitate withdrawal of the moulding, the tube or rather the inner
surface of the tube is preferably made slightly conical in shape, the conical
taper towards that end opposite the plunger forming a cone angle of at most
3°.
In another embodiment of the invention, the refill cartridge is
characterized in that the tube has a length adapted to the free internal
holder
height of the stick, an internal diameter adapted to the internal diameter of
the
holder and a base serving as a plunger for the stick.
As mentioned above, this refill cartridge comprises a tube which
CA 02269124 1999-04-27
surrounds the spreadable product mass and of which the length substantially
corresponds to the free internal height of the stick tube, but may even be
only
a fraction of the internal height of the stick holder. The tube has an adapted
internal diameter in the same way as the stick holder so that the moulding can
be drawn into the interior of the holder with simultaneous removal of the
tube.
To use the refill cartridge, that part of the plunger which is not covered by
the
tube is inserted into the holder to such an extent that, on rotation of the
knurled nut, the screwthreaded spindle engages in ttie screwthreaded bore
of the plunger. On further rotation of the knurled nut, the plunger is
gradually
drawn towards the base of the holder, the tip of the screwthreaded spindle -
after passing through the screwthreaded bore in the moulding - drawing the
product mass equally into the cylinder with simultaneous "cutting" of a
screwthread. Rotation of the knurled nut is continued until the plunger
reaches the base of the holder. In this position, the moulding has been fully
withdrawn from the tube so that the tube may be removed. The refilled stick
can now be closed by a closure cap at the open end of the holder, as known
from the prior art. The refilling process may be repeated indefinitely because
the plastic parts are not subjected to any significant wear when the knurled
nut is rotated either to apply the particular product or to refill the holder.
To prevent air from being trapped in the stick holder during
introduction of the refill cartridge into the holder, a further embodiment of
the
invention is characterized in that the moulding is formed in its outer
circumference with a longitudinal groove or notch.
The invention is described in more detail in the following with reference
to the accompanying drawings, wherein:
Figure 1 is a side elevation of a moulding.
Figure 2 is a plan view of another embodiment of a moulding.
Figure 3 shows another embodiment of a moulding with part of a
mould.
Figure 4 shows another embodiment of a moulding.
CA 02269124 1999-04-27
1 ~0
Figures 5 and 6 are each side elevations, partly broken and in section,
of an adhesive stick surmounted by a moulding in another embodiment.
Figure 7 is a cross-sectioNside elevation of a refill cartridge according
to the invention.
The example described in the following relates to an adhesive stick
where the product mass 23 consists of spreadable, soft and plastic adhesive.
The cylindrical moulding 2 shown in Fig. 1 consists of soft and plastic,
spreadable adhesive mass 23. In its three-dimensional form, the moulding
2 is so adapted to the internal volume - designed to accommodate the
adhesive mass - and internal configuration of the holder that it can be
introduced into the holder of the adhesive stick in the direction of the arrow
3 and pushed andlor drawn completely into the holder. One example of such
a stick is described in the following with reference to Figs. 5 and 6. In its
most simple form, the stick is a smooth-surface cylindrical moulding 2.
Figure 2 is a plan view of a cylindrical moulding 2 which is provided on
its outer circumference with a longitudinal groove or notch 4. Air is able to
escape from the interior of the adhesive stick holder along this groove 4 when
the moulding 2 is introduced into the holder.
Figure 3 shows a moulding 2 of spreadable adhesive mass 23 which
is provided at one end with a plunger. Figure 3 shows the moulding 2 still in
the mould 6 (partly shown) immediately after casting of the adhesive mass 23,
which is still liquid during the production process, and its solidification.
Overall, the plunger is cup-shaped with a cylindrical projection 7 at its
center.
Annularly projecting collars 8 and 9 are formed on the inside of the plunger
and the outside of the cylindrical projection 7. These collars ensure safe
anchoring of the adhesive mass 23 in the cup-shaped plunger and prevent
the plastic adhesive mass 23 from being torn or sheared off during
introduction of the moulding 2 into the holder of an adhesive stick.
Figure 4 shows another embodiment of a moulding 2 of spreadable
adhesive mass 23 comprising at one end a plunger 11 formed at its center
CA 02269124 1999-04-27
11
with a screwthreaded bore 10 extending over the entire length of the plunger
11. The plunger 11 is cup-shaped and is provided on its inside with annularly
projecting collars 12. A blind bore 13 is formed in the moulding 2
concentrically to its longitudinal axis.
The mouldings shown in Figs. 1 to 4 are longitudinally surrounded (not
shown) by a tube, as described in the following with reference to the
embodiment of the refill cartridge 1 e.
The adhesive stick 14 shown in Figs. 5 and 6 is known in principle
from the prior art. It consists of a holder 15 with a solid base 16 into which
a
stick rotatable about its longitudinal axis is fitted by means of a snap-in
joint
(not shown). The stick, which extends over the entire longitudinal axis of the
holder, is formed by a screwthreaded spindle 17 beyond one side of the
snap-in joint and by a hand-operated knurled nut 18 beyond the other side of
the snap-in joint outside the holder 15. A plunger 19 is mounted in the holder
15 for longitudinal displacement by means of the screwthreaded spindle 17.
Since fitted mouldings 2 with plungers 19 and tubes 22 are shown in Figs. 5
and 6, the Gosure cap which is normally designed to be pushed on over the
upper edge of the holder is not shown. It can be removably fixed to the
outside of the holder by means of drop-in connections 20 or screwthreaded
or snap-in joints.
In its base, the plunger 19 is formed with a screwthreaded bore 21 in
which the screwthreaded spindle 17 is designed to engage. The plunger 19
forms the bottom part of a refill cartridge which otherwise consists of a tube
22 of which the lower rim encloses and/or surrounds the upper edge of the
plunger. The upper end 22a of the tube (Fig. 6) may be closed to prevent the
spreadable adhesive mass 23 from drying out. In addition, the plunger base
may have a breakable membrane 24 (Fig. 6) which closes the screwthreaded
bore 21. The cone 25 formed on the inside of the plunger base acts as an
insertion aid. In addition, the plunger 19 is formed on its outer surtace
along
its longitudinal axis with groove-like depressions 26 which widen triangularly
CA 02269124 1999-04-27
' 12
towards the underneath of the plunger and which, in conjunction with
corresponding ribs 32 on the inner surface of the holder, prevent the plunger
19 from rotating when the knurled nut 18 is turned.
An embodiment of a refill cartridge 1 a according to the invention is
shown in Fig. 7 which is largely distinguished by the development and use of
a sleeve 27. In the same way as the tube 22, the sleeve 27 is cylindrical in
shape and is connected to the tube 22, for example by an annular snap-in
joint 28. The sleeve 27 has such an internal diameter 29 that it can be
pushed onto the outside of the holder 15 (see Figs. 5 and 6). The holder 15
slips into the annular space 30 between the sleeve 27 and the plunger 19, the
refill cartridge 1 a being securely fixed and centered in relation to the
adhesive
stick 14.
In the present case, the sleeve 27 is pushed over the holder 15 until
the face 15a (see Fig. 5) and the annular stop surface 27a are in contact with
one another.
However, the sleeve 27 can also be made in one piece with the tube
22, in which case the inner radial cross-section is increased in the vicinity
of
the connection between the tube 22 and the sleeve 27 with formation of an
annular face similar to the stop surface 27a.
The plunger 19 is joined to the sleeve 27 by radially extending bridges
31 which break during the refill process, i.e. when the plunger 19 is moved
towards the base 16 of the holder, so that the plunger is separated from the
sleeve 27. Above all in the embodiment in which the tube 22 and the sleeve
27 are made in one piece, the plunger 19 may also be connected to the
above-mentioned one-piece moulding 22, 27 by a releasable drop-in or snap-
in connection. All parts may be injection mouldings which, if they are in one
piece or are to be joined to one another, may even be produced in a single
operation.
The cross-sectional geometry of the refill cartridge 1 a must of course
be adapted to that of the holder 15 of the adhesive stick 14; for example, the
CA 02269124 1999-04-27
1~3
adhesive stick could even be polygonal rather than cylindrical.
The blind hole 13 is preferably of such a diameter that, on entering the
blind hole 13, the screwthreaded spindle 17 cuts only slightly into the
adhesive mass 23 so that there is little, if any, radial expansion of the
moulding 2 or displacement of the adhesive mass 23 on introduction into the
holder 15.
The refill cartridge 1 a may be packed in the usual way in films, paper
or filmlpaper composites. Sealed-rim bags, thermoformed parts, mouldings
of mechanical wood pulp or starch derivatives, for example, are also possible.
Several refill cartridges may also be accommodated in a single pack from
which they may be individually removed, for example by tearing or breaking
off.
It is also possible to line the mould 6 with packaging material, for
example plastic film, before it is filled with the adhesive mass 23. In this
case, the packaging material acts as a separation aid. To this end, the
packaging material is introduced before the adhesive mass 23 is poured into
the mould 6 and before the optional introduction of plungers 11, 19 andlor the
tube 22 with the sleeve 27, preferably in such a way that it conforms closely
to the inner surfaces of the mould.
To refill adhesive sticks, the packaging material surrounding the
particular refill cartridge is first completely or partly removed.
A packaging-free sleeve end of the refill cartridge 1 a is then applied
to the opening in the end of an adhesive stick holder 15 and the moulding 2
is subsequently drawn into the holder 15. The refill cartridge 1 a is first
pushed gently with the plunger 19 into the holder 15 until the end 17a of the
screwthreaded spindle 17 engages in the screwthreaded bore 21. Through
continued rotation of the knurled nut 18, the plunger 19 is drawn further
downwards until the annular contact surface 27a comes into contact with the
opposite front face 15a of the holder 15. With continued rotation of the
screwthreaded spindle 17 through rotation of the knurled nut 18, the plunger
CA 02269124 1999-04-27
14
19 is drawn continuously downwards, the screwthreaded spindle 17
simultaneously cutting a thread into the adhesive mass 23 and pulling the
moulding 2 uniformly downwards. The position of the tube 22 relative to the
holder 15 remains unchanged so that, finally, the column of adhesive 23 is
completely removed from the tube 22. Since the length of the tube is adapted
to the internal height of the holder, the free end face of the adhesive mass
is
flush with the upper edge of the holder 15 so that the tube 22 can be removed
completely empty with the sleeve 27. The adhesive stick 14 has been refilled
and can be reused.
