Note: Descriptions are shown in the official language in which they were submitted.
~t7s~ 3
IMPROVED CUP ~IM AND METHOD
~CKGROUND OF q~ MVENTION
Thi.s invention relates to an improved cup.
Specifically, the invention concerns an :improved rim
structure for a cup made from a material having at least
one foamed layer and at least one non-foamed layer.
It i9 understood by those familiar with the art
that single use drinking cups for holding both hot and
cold beverages can be fabricated from extruded expanded
polystyrene sheet (commonly referred to as "foam").
When the foam material is suitably oriented in the
machine direction during extrusion, cups may be
fabricated from rectangular blanks which are formed into
cylindrical sleeves by slightly overlapping the ends of
the rectangular blank, heating the adjacent surfaces,
and applying suitable pressure to produce an impervious
sealed seam. T~e resulting cylindrical sleeve is shrunk
to a frusto~conical shape. In forming a two-piece cup,
a polystyrene foam disc may be used to close the bottom
circular opening of the frusto-conical cup. Such a
known cup and method of making the cup is disclosed, for
example, in U.S. Patent No. 3,854,583. A known method
and apparatus for forming such cups is disclosed in U.S.
Patent No. 3,969,173.
A more recent development in cup technology permits
the use of structures consisting of layers of different
materials, for example, a foamed layer coincident with a
non-foamed layer wherein the different layers have
different properties. For example, one layer may be a
polystyrene foam while the other layer is a non-foamed
polystyrene layer forming a plastic skin. Cups made
from a combined foamed and non-foamed plastic material
generally have the foam layer on the inside of the cup
and the solid plastic layer on the outside, which
permits a glossy smooth outside surface more amenable to
printing. When a multi~layered material having layers
of different materials is used, however, fabrication of
the cup, particularly the rim, becomes more difficult
than with a conventional single material, such as foam.
:,, ' ' :
. ~
' ' ' ' . ', ' '
:
75~ 3
-- 2 ~
When a multi-layered, multi-material sheet is
fabricated into a cup, forming a smooth rolled rim
around the mouth of the cup becomes difficult due to the
difference in properties, such as stiffness, betwe~n the
different materials. What generally results is a rim
having an undesirable series of flat sections within the
rim roll rather than a smooth curved contour. The
resulting irregularly shaped rim makes it difficult to
fit a standard lid on the cup without the lid leaking
around the rim. rrhe irregularly shaped rim also
provides a less pleasing appearance.
Accordingly, it is an object of an aspect of the
present invention to provide a cup made from a multi-
layered, multi-material sheet in which the rim roll may
be fabricated with a smooth curved contoux.
Accordingly, it is an object of an aspect of the present
invention to provide an improved method of making a
smooth curved contour rim roll on a cup made from such a
material.
SUMMARY OF T~E INVENTION
Various aspects of the invention are as follows:
A cup-like container having a sidewall, an ope~
mouth defined by the upper portion of said sidewall, and
closing means for closing the bottom o~ said sidewall in
a liquid tight manner, the improvement wherein said
sidewall is made from a material having at least one
foamed plastic resin layer and at least one non-foamed
plastic resin layer and wherein a plurality of score
lines are formed in said sidewall adjacent said open
mouth on the outside surface of said sidewall and in the
direction of curling so that said score lines will
weaken said ~idewall, said score lines comprising
creases which do not penetrate through said non-foam
layer; said plurality of score lines being formed
parallel ko the circumferential direction of said
sidewall ko predetermine the positions on sald resin
) .
' . .
~: , ,'.,. : '
,- ' -: :
.
~l~tj15~
~ 2a -
sidewall whare said si~ewall will curl so that said
scored upper portion of said sidewall will curl into a
thin tight bead forming a smooth uniform curled contour
which surroun~s the open mouth of the cup-lik~ container
and forms the upper and outer circumferential rim of the
cup-like container.
A method of making a smoothly curved rim for a cup-
like container comprising the steps of:
forming a plurality of score lines parallel to the
circumferential direction of a web of coextruded
thermoplastic material, said material being oriented
during extrusion;
forming said oriented web of material into a
plurality of rectangular blanks, forming said
rectangular blanks into a plurality of cylindrical
sleeves, heat shrinking said cylindrical sleeves on a
frusto-conical mandrel to form a sealed cup-like
container having a sidewall, an open mouth at the upper
portion of said sidewall and a closed bottom portion at
the bottom of said sidewall, said score lines being
adjacent said open mouth;
pressing said upper portion of said sidewall first
downwardly and outwardly, then inwardly, then upwardly
along said score lines into a thin, tight bead to form a
smoothly curved rim which surrounds said open mouth and
forms the upper and outer circumferential rim of the
cup-like container.
A cup-like cont2iner comprising:
a sidewall made from a single sheet o~ a
coexkruded, oriented, heat-shrinkable thermoplastic
material having at least one foamed layer and at least
one non-foamed layer, ~aid foamed layer having a density
les~ than the density of said non-foamed layer, the ends
of said sidewall being joined to one another to form a
cylindrical sleeve having a liquid tight seam extending
from the top to the bottom of said container so that
. ~ .
'~
. ~ .
.
.
, ,
~'7~ 3
- 2b -
said sleeve can be positioned on a frusto-conical
mandrel and heat-shrunk to ~orm the cup-like container;
a mouth at the top of said container defined by the
upper portion of said sidewall;
a plurality of score lines formed in one of said
layers adjacent said mouth at said upper portion of said
sidewall to predetermine the positions on said sidewall
where said sidewall will curl, said score lineæ being
formed on the outside surface of said sidewall in the
direction of curling to form creases which do not
penetrate through said non~foamed layer: and
a thin tight bead having a smooth uniform curled
contour, said bead forming the upper and outer
circumferential rim of the cup-like container.
By way of added explanation, in accordance with an
aspect of the present invention, an improved cup-like
container is disclosed. The container has a side wall,
an open mouth defined by the upper portion of the side
wall and closing means for closing the bottom of the
side wall in a liquid tight manner, thus de~ining a
conventional drinking cup container. The closing means
may be any means commonly used and well-known in the
prior art to make either one-piece CUp5 or two-piece
cups. Most drinking cups include a rim or thin tight
25 bead around the mouth of the cup. The present
invention provides a plurality of score lines formed in
the ~ide wall r parallel to the circumferential direction
of the side wall, adjacent the
,
"
:: - . ............. .
. -'~ ' ' ~ ' . ' ' ~ ' ' ' .
'7S~ 3
open mouth defined by the upper portion of the side wall. The score
lines are preferably formed by creasing the side wall materi~l so that
the score lines will weAken the side wall. The scored upper portion
of the side wall is reversely folded into a thin tight bead which
surrounds the open mouth of the eu~like contfliner to form a smooth,
curved rim.
Preferably, the cup is made from a coextruded material having a
foamed plastic resin layer 1nd H non-foQmed pl~stic resin layer. The
non-foamed l~yer may be either on the inside or on the outside of the
cup according to specific end use requirements. The score lines are
preferably formed in the direction of bending, that is, in the outside
layer when a reversely folded rim is formed. A reversely folded rim
is one which is curled tow~rds the outside of the cup.
BRIEF DESCRIPTION OF THE DRAWlN GS
Figure 1 is an ele~rational view p~rtly in section of a cu~like
container in accordance with the present invention.
Figure 2 is a detail of the side wall of the cup shown in
Figure 1.
Figure 3 is a schematic view illustrating the formation of score
lines in a web of material to be formed into a cup.
Figure 4 is 8 detailed view of the tool used to form the score
lines.
Figure 5 is a det~iled new of the score lines formed in a web
of rnaterial.
Figure 6 is a fragmentary enlarged sectional view of a cup side
wall ss)d rim according to the present invention.
DETAILED l~ESCRIPTION OF A PREFERRED EMBODIMENT
The preferred embodiment of a nestable insulated cup 10 is
shown in Figure 1 constructed in two parts, including ~ sidewall 20
and fl sealed bottom disc 11. Alternatively, cup 10 may be made AS
one~piece cup in accordance with well-known manufacturing proce-
dures. Cup 10 is manufactured using known techniques ~s disclosed in
.
~, ' . ,
the U.S. pAtentS cited above. In general, the rect~ngul~r side waII
blanks are severed from A web of sheet materisl having ~ biaxial ori-
entation5 that is, an orientfltion in both the longitudinal and transverse
directions. However, the orientations in each direction need not be to
the same degree. A eylindrical sleeve is forrned from the blank with
the machine direction of the web extending circumferentially around
the cylindrical sleeve. A liquid tight lapped seam is formed between
the ends of the sleeve such as by heat sealing. The sleeve is then
placed over a forming msndrel having an outer surface corresponding
to the desired configuration of the inner surface of the side wall of
the cup to be forrned. The sleeve, while it is so positioned over the
mandrel, is heated to csuse it to heat shrink into conforming face-to-
face contact with the forming surface of the mandrel. The shrunken
sleeve is stripped from the mandrel. A separate bottom closure may
be affixed to the side wall while the sleeve is still in position on the
mandrel or after it is removed by any of several Icnown cup
manufacturing techniques. Alternatively~ a one-piece cup may be
formed.
Cup 10 contains a rolled, reversely curled rim shown generally
at 12, and also shown in section at 13. Stacking shoulder inaents 14,
also shown in cross-section at 15, may be provided at the bottom of
sidewall 20, as shown in Figure 1. Such indents are proYided to
improve nesting of one cup within another.
As shown in Figure 29 the cup body or sidewall 20 is preferably
made from a rectangular blank of oriented polystyrene msterial
extruded with a non-foamed skin layer 21 of solid polystyrene and a
layer 22 of polystyrene foam coextruded w;th layer 21. Although
polystyrene is a preferred material, other thermoplastic polymeric
materials also may be used. Additionally, the invention is equally
applicable to materiàls having more than two layers, such as a mate-
rial having a layer of foamed material sandwiched ~etween two layers
Or ~ non-foamed materia~.
.. ,
. .:
. ~ .
. .
s~
In accordance with the present invention, and using known fabri-
cstion techniques, a sheet consisting of a foamed plastic resin, such as
polystyrene, is extruded from ~n annular die, in combination with a
non-foamed pl~stic resin to form fl coextruded material. Alternatively,
the layers may be laminated rather thfln coextruded or formed using
other fabrication techniques. Also, a multi-layer, i.e., ~ material
having more than two layers may be used. Preferebly, fcamed
layer 22 makes up ~pproximatley 9696 of the total caliper of the
coextruded sheet and non-foamed or solid l~yer 21 applooximates 4% of
the total caliper. A separate extruder may be used to supply solid
layer 21 by m eans of cross over pipes so as to surround the foamed
extruded material just prior to exiting the annular die. (3enerally, the
extruded layers are giYen a biaxial orientation in both the machine,
i.e., lengthwise, direction as well 8S the transverse direction of the
sheet of material~ that when heated, a formed cylindric~l sleeve will
properly shrink into conformance with a mandrel. The orientation in
the machine direction may readily be imp~rted to the web of mAterial
by engaging the material while it is at a suitable orientation tempera-
ture between opposed counter rotating rolls which are driven at periph
eral speeds substantially in excess of the linear speed of the
thermoplastic material leaving the extruder. Additional longitudinfll ori-
ent~tion &nd transverse orientation is provided as the sheet lea-res the
extruder die, all as is well understood in the art.
As shown in Figure 3, a web 30 of coextruded materi~l is
scored in the ~rea subsequently to be curled into rim 12 of cup 10
with a series of parallel lines 33. A dri~ren wheel 31 having parallel
bosses or projections 32 may be used to form score lines 33. Prefer-
ably, projections 32 are positioned approximately 1/32" apart on centers
contoured such th~t ~ .005" fl~t occurs as the edge of sn included
engle of 60 with a projected depth of 1/32". The preferred configu-
r~tion of projections 3a is shown more particularly in Figure 4. The
depth of score lines 33 may be further controlled by adjusting the
s~
driven wheel 31 towards or away from the web so thnt the scoring
penetration of score lines 33 is enough to crease the solid layer 21
without cutting through leyer 21, ~s shown in Figure 5. The score
lines are formed in the direction of bending. When a reversely folded
r im is used, ~s shown, the score lines are in whichever layer is on the
outside of the cup sidewall.
Figure 6 illustrates rim roll 12 in detail showing score lines 33
formed in the upper portion of sidewall 20. As shown, the upper por-
tion of sidew~ll 20 is reversely folded into a thin tight bead which
surrounds the mouth of cup 10. In ~ccordance with known
m~nufacturing processes, a rimming or curling tool presses the upper
scored portion of sidewall 20 first downwardly and outwardly, and then
is contoured to force the material back toward the cup sidewall, and
then upwardly to finally provide a smooth rim curl contour. Scoring
lines 33 c~use a we~kening of the more resistant solid sheet layer 21
during the curling operation allowing the softer outer foam layer to
curl around in a generally circular fashion without buckling of the solid
layer. Score lines 33 predetermine the position where creasing of the
solid layer occurs during the rim curling operation to prevent
inconsistent1 randomly deformed rim curl shapes. Score- lines 33
weaken solid layer 21 so that rim 12 will have a smooth more
pleasing ~ppear~nce. Also, the smooth uniform contour of rim 12
ensures superior dimensional reliability of the rim diameter and the rim
Yertical thicknessS which are important ~or lid design and manufacture
to a leak-tight fit. A conventional lid would not efîectively seal a
cup h~ving a r~ndomly de~ormed rim.
When solid layer 21 is on the outside of the finished cup as
shown in Figures 1, 2 and 6, the outside surface of the finished fabri-
cated cup permits a more pleasing glossy surface highly receptive to
good quality printing using known flexographic or gravure printing
techniques for decoration. Alternatively, solid layer 21 m~y be within
the finished cup upon fabrication for certain end product applications.
~, - .
' . '
5~ 3
Although a preferred form of the invention has been described,
the invention is not to be limited thereto. V~rious modific~tions may
be rnade to the invention, which is limited only by the following
cl~ims.
.
