Note: Descriptions are shown in the official language in which they were submitted.
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HEADPIECE FOR COLLAPSIBLE TU13E
Back round of the Invention
g
Collapsible tubes are used, as dispensers for
toothpaste and shampoo. They are often referred to
as squeeze tubes. In forming a collapsible tube of
this type, the body or sidewall is formed separately
from the headpiece. The headpiece, generally, is
molded to the formed sidewall portionO
The sidewall is often a multi~ply, collapsible
sheet material having inner and outer plastic plies
usually polyethylene, an interior metal foil ply,
usually aluminum. The aluminum acts as a barrier to
oxygen penetration and flavorant migration. The poly-
ethylene protects the aluminum from the contents of
the tube, provides a convenient printing surface and
affects the feel of the tube to the end user. The
aluminum and polyethylene are combined in amounts
that pro~ide a desired collapsibility and avoidance
of spring back. All of this is known in the art and
will not be further discussed because the structure
of the sidewall does not form a part of this invention
except that the headpiece must be bondable to the
sidewall.
The headpiece of the tube provides a number of
functions. Because it forms one end of the collapsi~
ble tube, it must have structural integrity to prevent
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collapse in use. In addition, it must be formed of a
material which, like the materials in the sidewall,
prevents flavorant migration or deterioration of the
contents. Further, the material of the headpiece has
to be bonded to the plastic material of the sidewall
and it must resist corrosion from the contents of the
tube as well as avoid chemically reacting with the
contents of the tube. As these functions cannot be
provided by the same plastic material, the prior art
has attempted to provide othex solutions. For example,
a barrier member has been provided within the head-
piece~ adjacent the contents of the tube. This pre-
vents the migration or deterioration of the substances
held within the tube. However, the cost of separate-
ly forming and inserting this barrier member is high,so that its use is uneconomic. Further, there is a
problem in holding the barrier member to the rest of
the tube. -
It is an object of the present invention to
2~ provide a headpiece which provides both the structuralintegrity and the protection of the contents without
the necessity for an additional insert.
It is further object of the present invention
to pro~ide a method for forming a unitary headpiece
of two plastic materials in an expeditious and effi-
cient manner.
It is a still further ob~ect to provide an
extrusion die for use in forming a unitary headpiece
of two thermoplastio materials.
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Brief Descriptio_
In accordance with an aspect of the invention there
is provided in a die for extruding a hot plastic material
from an exit port at an end of the die to form an annulus of
plastic material~ the improvement comprising a cooled wiper
member movable ~e~ said end of said die to wipe off
whatever annulus of plastic material is formed on said end
of said die.
A unitary plastic headpiece for a collapsible squeeze
tube has two plastic portions. One of the two plastics is
compatible with bonding the headpiece to the plastic ply of
the collapsible side wall of the squeeze tube. The other
plastic is selected to prevent deterioration or migration of
the substances contained within the collapsible tube. This
dual-plastic unitary headpiece is achieved by extruding a
first plastic annulus and a second plastic annulus, each of
which have a torus type of shape, in succession, on top of
one another from a single extruder die. This dual annulus
structure is wiped from the die onto a lower mold piece
which mold piece has a configuration that defines the inner
surface of the headpiece to be formed. An upper mold piece
defining the outer surface of the headpiece to be formed is
brought into engagement with the lower mold piece to force
the two annuli into the shape of the desired headpiece.
Concurrently, the sidewall is supported around the lower
mold piece so that the upper edge of the sidewall comes into
contact with the plastic annuli and is bonded thereto.
During this essentially transfer molding technique,
the lower annulus becomes -an inner portion of the headpiece
while the upper annulus becomes the outer portion of the
headpiece. The upper annulus thus must be of a plastic
material compatible with bonding to the plastic ply of the
sidwall while the lower annulus must be of a plastic
material compatible with the ingredients of the tube and
tending to serve the functions of preventing deterioration
or migration of the substances within the tube.
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Variations in the xelative amounts of the
plastics in the upper and lower annul.i can affect the
extent to which, for example, the plastic forming the
inner portioll of the headpiece can also be used to
form or define a portion of the neck and threads of
the headpiece.
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Brief Description of the Drawings
FIG. 1 is a view of the top portion of a col-
lasible squeeze tube having a headpiece according to
the present invention. FIG. 1 is in part an elevation
view and in part a longitudinal sec~ional view of the
headpiece.
FIG. 2 is a longitudinal sectional view of the
extruder die employed to form the two annuli which
are the starting points for molding the plastic head-
piece of this invention, such as the headpiece shown
in FIG. 1.
FIG. 3 is a schematic illustration of a first
stage in the molding of the FIG. 1 headpiece. FIG. 3
illustrates the two annuli 28a/ 28b formed on the end
of the extruder die and positioned immediately above
the mold piece 34 employed to define the inner surface
of the plastic headpiece.
FIG. 4 is a view similar to FIGo 3 showing the
next stage in the operation in which a chilled wiper
plate 32 has pushed the two annuli 28a, 28b off the
die piece and dropped them onto the inner mold piece
34.
FIG. 5 shows the inner mold piece carrying the
two plastic annuli indexed over to a position under
and in alignment with the outer mold piece 36 which
defines the outer surface of the headpiece to be
molded.
FIG. 6 is a view similar to that of FIG. 5
showing the ouker mold piece 36 having engaged the
inner mold piece 34 to define the mold cavity which
forms the plastic headpiece from the two plastic
annuli.
FIG. 7 through 10 show the progressive forming
of the headpiece as the tube mold parts come together.
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These four FIG~. are in simplified schematic form and
illustrate the annuli in cross section, More specifi-
cally, FIG. 7 illustrates the two plastic annuli in
a condition correspond~ng to that of FIG. 4, ~IG. 8
illustrates the annult immediately after the inner
mold par~ has contacted the two annuli. ~IG. 9
illustrates a furth.er staye in the molding where the
two mold parts have partially come together, FIG, 10
illustrates the flnal stage of the molding when the
two mold parts have completed their progression toward
one another.
FIG. 11 is a cross sectional view showing a
second embodiment of the headpiece in which substane
tially less of the plastic B of the upper annulus 28b
and substantially more of the plastic A of the lower
annulus 28a is employed than is represented by the
embodiment shown in TIGS. 7 through 10.
FIG. 12 illustrates a still further embodiment
of this invention in whtch the amount of plastic B
employed in the upper annulus 28b and the amount of
plastic A of the lower annulus 28a are intermediate
between the amount~ employed to manufacture the head~
piece of FIG. 10 and FIG. 11,
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Description of the Preferred Emhodiments
FIG. 1 illustrates a collapsible tube 20 having
a cylindrical sidewall portion 22 and a plastic head-
piece portion 24. The collapsible wall portion 22 is
formed from one of the flexible web materials known
in the art such as a multi-ply web having outer
polyethylene plies and a center or interior aluminum
ply . ,
The headpiece portion 24 has an inner plastic
portion 24a and an outer plastic portion 24b. The two
portions together form a unitary headpiece 24. The
headpiece 24 is bonded to the wall 22 by plastic ad-
hesion of the outer plastic 24b of the headpiece 24
to the inner plastic ply of the wall 22. That bonding
is accomplished during molding of the headpiece.
The material of the outer plastic 24b is
selected to be bondable with the inner plastic ply of
the wall 22~ Most tube walls 22 presently employed
in the art have outer and inner polyethylene plies.
Therefore, the outer plastic 24b of the headpiece 24
is preferably formed of polyethylene. However, should
the composition of the inner plastic ply of the wall
22 be different, the outer plastic 24b of the head-
piece can be varied accordingly.
The inner plastic 24a must be compatible with
the contents of the tube and, in many cases, must
act to prevent deterioration of those contents; for
example, by preventing oxygen penetration. In cases
where the inner plastic 24a must be hygroscopic, it
can be formed of any of the standard polyamide mate-
rials generally sold under the name nylon. Though
nylon is particularly useful when it is important
that the inner plastic 24a be hygroscopic, nylon has
disadvantages. In particular, a hi~her temperature
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is required to effect molding of the nylon so that,
other factors being equal, greater cooli~g is also
required after formation of the headpiece. Thus,
slower processing is experienced employing nylon as
the inner plastic 24aO
Other materials which can be employed in
forming the inner plastic 24a are ionomers, such as
those sold by DuPont under the trademark Surlyn. At
present, polypropylene is the preferred material for
tha inner plastic 24a for the combined reasons of
cost, effecti~eness, and speed of manufacture.
The examples just given for the material of the
inner plastic 24a, i.e., polypropylene, polyamide and
ionomers, are the presently preferred types of mate-
rials for the inner plastic 24a when the outer plastic24b is formed of polyethylene. If the composition of
the outer plastic 24b is varied, the composition of
the inner plastic may have to be varied, so as to be
compatible with the material of the outer plastic,
while still retaining the necessary properties for
the inner plastic. -
Because ~f the method of forming this head-
piece, it is a unitary structure of plast.ic 24b com-
patible with bonding to a plastic ply of the sidewall
22 and plastic 24a providing protection for the pro-
duct contained in the tube. Thus it is not necessary
to insert a barrier member into the headpiece to pro
vide any additional properties.
FIGS. 2 and 3 show the die 26 for coextrusion
of the two plastics into the composite extrusion
which is then molded to form the headpiece 24. The
plastic A, which forms the lower annulus 28a and thus
the inner portion 24a of the headpiece, is fed to the
die 26 through inlet 26a as indicated by the arrow in
FIG. 2. The plastic B, which ~orms the upper annulus
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28b, and thus the outer layer 24b, is fed to the die 26
at inlet 26b, as indicated by the arrow in FIG. 2. The
structure of the die 26, including mandrels, collars,
etc., is known in the art and thus need not be more speci-
fically illustrated or described.
The thermoplastic material A fed at inlet 26a
follows a path in the die generally desiqnated ~y the ref-
erence designation A to exit at the port designated 30u
The thermoplastic material B enters the die at inlet 26b
and follows the path B to exit at the port 30. The extru-
sion sequence in the extrusion die 26 assures that the
plastic A is extruded first so as to form a lower annulus
28a and that plastic B is extruded immediately thereafter
to form the upper annulus 28b.
An a~ially movable water cooled wiper 32 in the
form of an annulus around the outlet neck of the extrusion
die 26 is used to wipe the plastic annuli 28a, 28b off the
neck of the die 26. After the two plastic annuli 28a, 28b
have been extruded from the outlet noz~le 30 of the extru-
sion die 26, these two annuli 28a, 28b will be sitting on
the lower end of the extrusion die 26. As soon as the two
hot plastic annuli 2Ba and 28b have been formed, the water
cooled wiper 32, is brought axially downward to wipe the
two annuli off the end of the die and cause them to drop
onto a lower mold piece 34, (see FIG. 4~.
The mold piece 34 is configured to define the inner
surface of the headpiece to be molded and thus can be
termed the inner mold piece. The sidewall 22 is held by
light friction fit around the inner mold piece 34 and ex-
tends upward into the area adjacent to where the hot plasticannuli fall to assure that contact will be made between
the inner plastic ply of the sidewall 22 and the hot plas-
tic of the annuli thereby causing the desired adhesion of
headpiece to sidewall. The wiper 32 is water cooled to
avoid having the hot plastic of the annuli stick to the
wiper 32 during the wiping operation.
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After the annuli have dropped onto the inner mold
piece 34 shown in FIG. 4, the inner mold piece 34 is indexed
to a position under and in alignment with an upper mold
piece 36 as shown in FIG. 5. The upper mold piece 36 has
a surface configured to define the outer surface of the
headpiece and thus can be called the outer mold piece.
This outer mold piece 36 includes a spring 38 loaded pin
40 that extends down into the cavity defined by the outer
mold piece 360
After the two mold pieces 34 and 36 have been
brought into the alignment shown in FIG. 5, they are brought
together, as shown in FIG. ~, into engagement thereby de-
fining a cavity in which the headpiece is molded. The pin
40 abuts against the upper edge of the inner mold piece 34
and is held tightly against the inner mold piece 34 by the
spring 38 to assure that the plastic material being molded
does not block the passage way 42 required through the head-
piece 24.
As can be seen in FIG. 6, the mold cavity although
primarily defined by the two major mold pieces 34 and 36
is also, in part, defined by the lower rim of the pin 40
and by the upper edge portion of the sidewall 22.
The mold is water cooled by water passages 44 to
effect cooling and solidifying of the plastic materials
A and B that form the molded head 24.
After formation of the headpiece in the mold as
described, the tube now having a formed headpiece is moved
to other positions for whatever finishing operations may
be required.
FIGS. 7 through 10 illustrate in somewhat ideal-
ized form the configuration of the plastic materials A and
B during the process of molding the finished headpiece 24
from the composite annulus structure 28a, 28b. FIG. 7
illustrates the composite extrusion of plastics A and B
on their formation as they are dropped from the outlet end
of die 26 onto the inner mold piece 34. As soon as these
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hot, fluid plastic mate~ials A and B contact the surface
of the inner ~old piece 34, they tend to assume the shape
shown in FIG. 8. Upon further movement of the two mold parts
34 and 36 together, the plastics A and B form the configura-
tion illustrated in FIG. 9 in which it can be seen that thelower annulus 28a has begun for form the inner plastic por-
tion A and the upper annulus 28b has begun to form the outer
plastic portion B. The completion of bringing together the
two mold pieces 34 and 36 provides the end result as shown in
FIG. 10; namely a headpiece 46 having integral plastic por-
tions A and B.
The headpiece 46 shown in FIG. 10 differs from the
headpiece 24 shown in ~IG. 1 in that the proportion of the
two plastics A and B are different. More particularly, FIG.
10 represents a situation where there is relatively more of
the plastic B than is the case in FIG. 1~
Further headpiece configurations 48 and 50 are shown
in FIGS. 11 and 12 in which different amounts of the plastics
A and B have been employed. The differences in the various
headpieces shown herein 24, 46, 48 and S0 are not due to
different methods of formation but are rather due to the
relative amounts of plastic materials A and B employed for
forming the upper and lower annuli 28b and 28a. Thus, for a
configuration of a headpiece shown in FIG. 11, the annulus
28a has to be substantially thicker than the annulus 28b
whereas in the configuration shown in FIG. 10, the relative
sizes of the annuli 28a and 28b are much more similar.
It is important that the outer part of the shoulder
portion of the headpiece be of the plastic B which is adapt-
ed to bond to the plastic ply of the sidewall 22. Dependingupon the materials involved, their relative costs and the
application, the neck portion of the headpiece may be formed
solely o the inner plastic material A with no covering of
the plastic material B.
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The change in rela~ive amounts of the two plastics
A and B can readily be accomplished by varying the shape
of the die 26 or by increasing the pressure on the plastics
fed at inlets 26a or 26b as appropriate, to vary the amount
of plastic extruded at the exit port 30~
In each case, the peripheral lower edge portion of
the headpiece is composed of the B plastic in order to bond to
the plastic ply of the tube sidewall 22. In each case, the
A plastic extends over the entire inner wall of the head-
piece to assure that the entire headpiece is impermeable.
The composition extrusion 28a, 28b can be formedby first extruding one of the plastics A through the annular
outlet 48a and annular exit port 30 as an annulus followed
by extrusion of the second plastic B through the annular
outlet 48b and exit port 30 as a second annulus. A slightly
different die configuration would permit extrusion of the
two annuli simultaneously. in any case, the composite dual
annulus 28a, 28b is extruded on the tip 26t of the die 260
