Note: Descriptions are shown in the official language in which they were submitted.
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LIQUID CONTAINER WITH UNINTERRUPTED
COMFORT BAND AND METHOD OF FORMING SAME
BACKGROUND
This application generally relates to containers for
liquids and more specifically, to a container having a
sidewall that provides an uninterrupted comfort band defined
by a sealed void between the liquid and an outer surface of
the container, and to a method for forming such a sidewall.
The above-cited US 6,536,657 (Van Handel) discloses a
disposable thermally insulated container having a sidewall
portion comprising a substrate layer and a film layer which
cooperate to define an insulating layer therebetween, thereby
maintaining the adjacent substrate material at a relatively
moderate temperature even if the substrate and the film are
not particularly resistant to heat transfer and the container
is filled with a very hot liquid. In at least some of the
described embodiments, the sidewall is formed from a sandwich-
like blank generally in the shape of an annular sector, with
two straight edges that are sealed together to thereby form an
overlapping vertical side seam of alternating substrate and
film layers without any insulation in the vicinity of the side
seam, thus potentially permitting that side seam to become
uncomfortably hot when the container is filled with a hot
liquid.
Now expired US 4,332,635 (Holbrook et al.) discloses a
method and apparatus for forming a label in the shape of an
annular sector and applying it to the exterior sidewall of a
previously formed cup in the shape of a tapered frustum.
Now expired US 4,197,948 (Amberg et al.) discloses a
method and apparatus for forming a tapered sidewall for a
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stackable cup by placing a previously formed cylindrical tube
of a heat shrinkable material over a heated mandrel.
SUMMARY
The sidewall portion of a cup or other container for a
heated beverage or other hot liquid comprises a relatively
rigid outer wall and a relatively flexible inner liner. The
wall and liner are attached together at respective upper and
lower circumferential bands, and at least an intermediate
portion of the liner between the upper and lower
circumferential bands is separable from the outer wall, to
thereby form a sealed void between the outer wall and the
inner liner which extends circumferentially along the entire
comfort band and which defines a comfort band encircling at
least a middle region of the cup.
In one embodiment, a PE coated first blank generally in
the shape of an annular sector has its two straight edges
sealed together along a vertical side seam, to form a
relatively rigid tapered outer sidewall having a generally
frusto-conical shape with an upper circumference greater than
a lower circumference. A similarly shaped second blank of a
shrink film material is formed into a similarly tapered inner
liner that is dimensioned so as to cover an interior surface
of the sidewall corresponding to a predetermined "comfort
band" encircling at least a middle region of the sidewall.
Alternatively, the outer sidewall may be formed without any
side seams and/or may include an integrally formed bottom
portion. The outer sidewall and liner are then sealed
together only at respective upper and lower edges of the
comfort band, preferably using a tapered mandrel equipped with
two selectively heated circumferential bands. Since at least
the respective central portions (including the central portion
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of any included side seam) of the outer sidewall and of the
inner liner are not attached to each other, the central
portion of the liner between the upper and lower edges will
tend to shrink into the interior in response to the
application of heat, thereby defining an insulating void
between the two bodies which extends about the full
circumference of the comfort band and which reduces the
thermal conductivity of the sidewall in the vicinity of the
comfort band.
In an alternative embodiment, a sleeve-like liner preform
is formed from two layers of shrink film material with a
respective side seam connecting the two layers at each of two
edges.
In another embodiment, the liner is formed by placing a
seamless preform over a tapered mandrel.
Optionally, a bond inhibitor may be used to prevent the
inner liner from being sealed to the outer sidewall except at
the upper and lower circumferences of the liner, thereby
facilitating a side seam to be formed using the same heated
mandrel as is used to seal the liner to the outer sidewall.
Preferably, the container is a stackable disposable cup
with a liner formed of a heat shrinkable material which is
activated (i.e., has its tension released) only when the cup
is being filled with a hot liquid. The sealing of the liner
to the outer sidewall is performed in a way that any heat
produced during the sealing operation is confined to the upper
and lower circumferences of the liner, thereby not releasing
the tension in the intermediate portion of the liner material
such that the liner remains in close contact with the outer
sidewall prior to use by the consumer and two or more unused
cups may be conveniently stacked inside one another without
the liner of a lower cup pressing against the outer sidewall
of an upper cup.
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The invention is defined in the appended claims, some of
which may be directed to some or all of the broader aspects of
the invention set forth above, while other claims may be
directed to specific novel and advantageous features and
combinations of features that will be apparent from the
Detailed Description that follows.
DRAWINGS
Certain characteristics, features and advantages of
various preferred embodiments are depicted in the accompanying
1o drawings, in which:
Fig. 1 is a partially cut away front perspective view of one
embodiment of a disposable insulated cup having a
defined comfort band;
Fig. 2 is a vertical cross section of the cup of Fig. 1;
Fig. 3 shows one embodiment of a machine for forming a
tapered inner liner from a single layer of heat
shrinkable material and securing it to the interior of
a previously formed outer body;
Fig. 3A shows an exemplary frusto-conical mandrel for use with
the machine of Fig. 3;
Fig. 4 shows an alternative embodiment of a machine for
forming the tapered inner body from a sleeve-like
preform consisting of two layers of heat shrinkable
material and for securing it to the interior of the
outer body;
Fig. 4A shows an exemplary two-layer preform such as may be
used in the machine of Fig. 4;
Fig. 4B is a more detailed view of an exemplary spreader such
as may be used in the machine of Fig. 4;
Fig. 5 shows an alternative embodiment of a machine for
inserting and securing the inner liners into the
respective outer sidewalls;
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Fig. 5A shows a first step in the insertion process performed
by the machine of Fig. 5;
Fig. 5B shows a second step in the insertion process performed
by the machine of Fig. 5;
Fig. 5C shows a third step in the insertion process performed
by the machine of Fig. 5;
Fig. 5D shows a fourth step in the insertion process performed
by the machine of Fig. 5; and
Fig. 6 shows an embodiment of a machine for forming a tubular
preform for the inner liner which is stretched onto a
tapered mandrel prior to insertion into the outer
sidewall.
DETAILED DESCRIPTION
Reference should now be made to Fig. 1, which is a partially
cut away front perspective view of one embodiment of a
disposable insulated cup 10 having a comfort band 12 defined
between upper edge 14 and lower edge 16 of an inner liner 18.
Upper edge 14 and lower edge 16 are sealed to the inner
surface 20 of an otherwise conventional disposable cup having
a relatively rigid sidewall 22 and bottom 24 formed from a
polyethylene ("PE") coated paperboard stock, with a partially
exposed vertical side seam 26 connecting the two straight
edges of the generally annular sector shaped blank from which
the outer sidewall 22 was formed. Cup 10 is preferably
tapered to facilitate stacking, with sidewall 22 extending
below bottom 24 by a sufficient distance to maintain a bottom
space 28 (see Fig. 2) between the bottom 24 and the table or
other support surface (not shown) on which the cup 10 may be
standing.
In accordance with one salient feature of the present
invention, as shown more clearly in Fig. 2, at least a portion
of inner liner 18 is separable from inner surface 20 of
sidewall 22 to thereby define an expandable void 30 which
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preferably encircles the entire circumference of cup 10 and
which expands in response to the application of heat to
provide thermal insulation between comfort band 12 and any
heated liquid in contact with inner liner 18. In particular,
the comfort band 12 is defined by a central portion of inner
liner 18 and a corresponding intermediate portion of outer
sidewall 22 disposed between upper and lower circumferential
sealing bands 14, 16 at respective upper and lower edge
portions of inner liner 18. Moreover, that insulating void 30
extends over at least an intermediate seam portion 32 of outer
sidewall vertical side seam 26. In the depicted embodiment,
the cup 10 has a height of about 5 inches, a major (upper)
diameter of about 3.50 inches, a minor (bottom) diameter of
about 2.375 inches; the comfort zone 12 is about 3 inches high
and is displaced from the top rim of the cup by approximately
1.50 inches. The upper and lower sealing bands 14, 16 each
have a width of about 0.125 inches. In an embodiment using a
liner 18 formed from a heat shrinkable material such as Bemis
Clysar 75 LE, the extent to which the central region of liner
18 shrinks away from sidewall 22 and into the interior of cup
10 depends on the maximum temperature of the liquid, and may
range from about 0.125 inches for warm (150 degree F) to about
0.50 inches for almost boiling (212 degree F) liquids. In
alternate embodiments (not shown) the comfort zone may be
wider or narrower, or at different heights, or even may extend
over the entire interior volume of the cup.
Fig. 3 shows a portion of a production line for tapered or
frustum shaped cups similar to that proposed in the referenced
U.S. Patent 4,332,635. As shown, a continuous web 34 of heat
shrinkable film is fed to a pair of rotary cutters 36, 38 and
the resultant lining blanks 40 each generally in the shape of
an annular sector are separated from the web 34 onto
correspondingly shaped areas 42 on the outer periphery of a
vacuum drum 44. Each blank 40 is in turn offloaded from drum
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44 onto a frusto-conical shaped vacuum mandrel 46 (shown in
more detail in Fig. 3A) which is rotating in synchronization
therewith, by suitable manipulation of the respective vacuum
applied to areas 42 of vacuum drum 44 and to holes 48 of
mandrel 46. The two straight edges 50 of blank 40 are then
heat sealed together by means of a heated vertical band 52 on
mandrel 46, thereby forming a frusto-conical shaped liner 18
with a corresponding vertical seam 54 (see also Fig. 1).
Next, a previously formed and otherwise conventional
uninsulated cup 56 is dropped in an inverted orientation onto
similarly oriented mandrel 46 from an stack 58 of such cups by
means of a second set of vacuum holes 60 at the upper surface
62 of inverted mandrel 46, and a second set of heated bands
64, 66 (at upper edge 68 and lower edge 70 respectively of
inverted mandrel 46) seal the previously formed liner 18 at
respective lower 16 and upper 14 circumferential sealing bands
(see Fig. 1) to corresponding circumferential bands on the PE
coated interior 20 of uninsulated cup 56 (see Fig. 1).
Heated bands 52, 64, 66 are preferably thermally isolated from
the other surface portions of mandrel 46 and may be heated in
conventional fashion by nichrome ribbon energized by an
impulse power supply. In an alternative embodiment (not
shown), the upper sealing band 14 and lower sealing band 16 of
liner 18 can be sealed to the inner surface 20 of uninsulated
cup 56 by means of a suitably heated external clamp or cuff
which transfers heat through outer sidewall 22 to inner liner
18.
In accordance with another salient feature of the present
invention, the intermediate portion 76 (see Fig. 2) of inner
liner 18 disposed between upper and lower heated bands 64, 66
is preferably not secured to the inner surface 20 of cup 10;
in particular, suitable precautions should be taken to ensure
that at least inner surface 20 is not inadvertently sealed to
those portions of the side seam 54 of liner 18 formed by
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heated vertical band 52 that are not in close proximity to
upper and lower heat seal bands 64, 66. For example, the
unfinished cup 56 may not be loaded onto mandrel 46 over liner
18 until the heat sealed liner seam 54 between edges 50 has
cooled, or else a suitable release agent 74 (such as silicone
grease) may be applied (as shown in Fig. 2) to at least the
intermediate portion 76 of the heat sealed seam 54 before the
uninsulated cup 56 is loaded. Alternatively, it may be
possible to construct the portion of inner surface 20 within
comfort band 12 (where any such adhesion is undesired) such
that it will not adhere to inner liner 18 during fabrication
and subsequent use. Similarly, if the sidewall 22 is formed
on the same mandrel 46 as is used to form the inner liner 18,
precautions should be taken to ensure that intermediate
portion 32 of sidewall seam 26 is not inadvertently sealed to
liner 18.
Fig. 4 shows an alternative embodiment of a machine for
forming a tapered inner liner 18' with two side seams 54 from
a sleeve-like preform 78 (see also Fig. 4A) prior to securing
it to the inner surface 20 of the rigid sidewall 22. Two
stacked layers of shrink film 34' (either from two separate
coils 80, 82, or from a single web that has been folded
lengthwise, or from a flattened tube) are fed between a pair
of opposing sealers 84, 86, which form two angled side seams
88, 90 of sleeve 78 at each side of centerline 92. A rotary
cutter 94 then die cuts (or perforates) the upper edge 14' and
lower edge 16', to thereby form a flattened sleeve 78, with
each cut edge 14', 16' corresponding to one half of a
corresponding upper edge 14 or lower edge 16 of the finished
liner 18'. Any remaining trim is disposed of (possibly using
vacuum to separate along seams 88, 90 and edges 14', 16'), and
the preform sleeve 78 is opened by a vacuum operated spreader
96 (see also Fig. 4B) which is provided with an opposing pair
of small reciprocating suction cups 98 for opening the flat
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sleeve so that the thus-opened sleeves 78 may be vacuum
secured to the interior of spreader 96 and separated from the
web 341.
When opened, sleeves 78 have a frusto-conical shape similar to
that previously described with reference to liner 18 of Fig. 3
and can be loaded by spreader 96 directly onto a mandrel 46'
that differs from mandrel 46 of Fig. 3A only in that it does
not require a separate side seam heat band 52. In particular,
a vacuum applied through holes 48 will serve to transfer the
resulting frusto-conical liner 18' from spreader 96 onto
mandrel 46'. As shown, mandrel 46' is mounted on a moveable
support 100 and is moved along loading axis 102 into its
position within spreader 96; alternatively, spreader 96 may be
provided with a translation mechanism for moving the spreader
96 and the liner 18' along loading axis 102 onto position
about mandrel 46'. The remaining steps of sealing the upper
and lower circumferential bands 14, 16 at the respective upper
and lower edge portions of liner 18' to the inner surface 20
of the not yet insulated cup 56 may be the same as described
for Fig. 3 and will not be further described, other than to
observe that since there is no side seam heat band 52, only a
minimal amount of heat is applied by mandrel 46' to comfort
band region 12 and it may not be necessary to take any special
precautions for preventing the intermediate region 76 of liner
18' from adhering to the inner surface 20. In alternative
embodiments (not shown), electrostatic forces could be used
instead of vacuum to position and hold the relatively
lightweight film of liner 18' to spreader 96 and/or mandrel
461.
Fig. 5 shows an alternative embodiment of a machine for
inserting and securing the inner liners 18' formed from
preform sleeve 78 into the respective uninsulated cups 56.
This particular embodiment is designed to provide a more
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continuous operation that may be more suitable for a low cost
mass production environment. The flattened preform sleeves 78
are sealed and cut as previously in the heat sealer 84, 86 and
rotary die cutter 94 stations along the production line, but
with an orientation that differs from what has been previously
described by 90 , i.e., the sleeve centerline axis is
perpendicular rather than parallel to the motion 102' of
sleeves along the production line. Rather than a single
reciprocating spreader 96, there are a number of such
spreaders 96, with the two spreader halves 104 of each
spreader traveling in separate counter-rotating continuous
motion paths 106, 108 on either side of the moving sleeves 78.
As the two spreader halves 104 of the same spreader 96 advance
in unison in the general direction of production line motion
102', each with its respective articulated suction cup 98 in
contact with the moving sleeve 78, each cup 98 is gradually
withdrawn into its respective spreader half 104 as the two
halves move in unison from the beginning 110 of the narrow
strait between the two spreader paths 106, 108 to a final open
position 112 at the end of that strait, and then return along
the far portion of their respective loop 106, 108 back to the
beginning position 110. After it exits from the end 112 of
the strait portion of the spreader paths 106, 108, the now
opened inner liner 18' is transferred to a mandrel 46'
traveling in the same direction but on a heat sealing loop
114, and above a corresponding cup receiver 116 traveling on a
cup receiving loop 118.
All four closed paths 106, 108, 114, 118 are provided with
translating conveyors (belts, chains, rails and the like) for
keeping the relevant tooling in coordinated motion along the
production path 102' as the liner 18' is placed over the
mandrel 46', and then both the mandrel 46' and the liner 18'
are placed inside a not yet insulated cup 56 that has
previously been placed in the waiting cup receiver 116.
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Fig. 5A shows schematically the opened liner 18' still
attached to moving spreader halves 104 at first position 120
along sealing path 122 defined by the intersecting portions of
heat sealing loop 114 and above cup receiving loop 118, with
opened liner 18' suspended below a similarly moving mandrel
46' and cup receiver 116. Fig. 5B shows liner 18' at a second
position 124 along sealing path 122, where it is no longer
attached to the spreader halves 104, but is now secured to the
mandrel 46'. Fig. 5C shows a third position 126 along sealing
path 122 in which the liner 18' and mandrel 46' are now in
position inside cup 56 which is still supported by cup
receiver 116 as the upper edge 14 and lower edge 16 of inner
liner 18' are being sealed to inner surface 20 of rigid
sidewall 22 by the heat and pressure emanating from mandrel
46' and/or receiver 116. Fig. 5D shows a fourth position 128
at which the thus formed insulated cup 10 (still secured to
mandrel 46') is being removed from cup receiver 116. The
uninsulated cups 56 are loaded into the cup receivers 116 at
entry point 130 on cup receiving loop 118 and the insulated
cups 10 are removed at exit point 132.
Fig. 6 depicts an exemplary machine for forming a tubular
preform 134 for yet another variant of an inner liner 18"
which can be stretched onto a desired shape prior to having
its upper edge 14 and lower edge 16 sealed to the inner
surface 20 of the rigid sidewall 22. As depicted, two rolls
80', 82' of a suitable plastic material are joined at their
side edges 136 to form a tube 34" with lateral fins 138.
Although the inner diameter 140 of the tube is substantially
less than that of the maximum outer diameter 142 of the
stretching mandrel 144, the fins 138 provide convenient
attachment points for grippers 146 to pull the tube along
stretching mandrel 144 and onto cup mandrel 46". Since the
resultant liner 18" is thus pre-stretched prior to being edge
sealed to the interior of cup 10, the central portion under
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comfort band 12 will tend to shrink into the interior of cup
even without the application of any heat, and thus this
particular embodiment may find application even where the use
of heat shrinkable materials is not practical. In an
5 alternative embodiment, the tubular preform 134 initially has
an inner diameter 140 greater than the maximum outer diameter
148 of the cup mandrel 46", and the heat shrink properties of
the material are used to shrink and shape the preform to the
external configuration of the mandrel 46" prior to inserting
10 the mandrel 46" into the complementarily shaped rigid sidewall
22. In either case, the elongated tube stock 34" is sectioned
into individual preforms 134 as it is being placed on cup
mandrel 46" possibly using already existing perforations (not
shown) in the tube stock.
Other implementations and enhancements to the disclosed
exemplary apparatus and processes will doubtless be apparent
to those skilled in the art, both today and in the future.
For example, the invention may be applicable to containers
other than disposable cups for hot beverages and/or to
containers having a shape more complex than a simple
orthogonal circular cone. As another example, the interior
of an uninsulated cup made of other materials and/or by other
processes not expressly mentioned above may be covered in
whole or in part with a flexible lining that forms an
insulated comfort band defined by a circumferential void
between the outer wall and the lining.
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