US 3028798 A
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XE lf702 K. P. ALLEN METHOD OF FORMING A PAPER CUP 2. Sheets-Sheet 1 Filed May 7, 1958 IN VEN TOR.
April 10, 1962 K. P. ALLEN METHOD OF FORMING A PAPER CUP 2 Sheets-Sheet 2 Filed May 7, 1958 BY w ATTORNEYS Unitfid States Patehtf) 3,028,798 METHOD OF FORMING A PAPER CUP Kenneth P. Allen, Easton, Pa., assignor to American Can Company, New York, N.Y., a corporation of New Jersey Filed May 7, 1958, Ser. No. 733,550 5 Claims. (Cl. 9355.1)
The present invention pertains to a method of forming a paper cup and in particular, to the method of sealing the end closure or bottom of the cup to the side wall of the body.
The present invention can be used with paper cups having any transverse cross sectional shape, e.g. circular, triangular, square, polygonal, etc., and any longitudinal cross-sectional shape, e.g. sides parallel, tapered inwardly towards the bottom, tapered outwardly towards the bottom, etc. While retaining these broad aspects of the instant invention, the invention will be described in relation to paper cups which meet the tapered type wherein the cross sectional dimensions at the bottom are smaller than the cross sectional dimensions at the top and in particular to paper cups having a frusto-conical shape wherein the cross-sectional diameter of the cup is least at the bottom thereof.
This construction and shape causes considerable difliculty in forming the conventional hemmed bottom edge It is another object to provide a method of the character described wherein a thermoplastic adhesive on the end closure and adjacent body portions of a paper cup are heated in a novel manner.
Yet another object is to provide a method of forming a paper cup wherein a thermoplastic adhesive on the paper surfaces to be joined is heated to a tacky condition without physically contacting the surfaces with a heating tool.
Still a further object is to provide a method of the character described wherein a polyethylene coating on the inside of the bodyof a paper cup andon the end closure therefor acts as the adhesive for bonding the body and end closure together. a 1
Another object is to provide a quick and eflicient meth-' od of heating a thermoplastic adhesive on the body and end of a paper cup to render the adhesive soft and tacky.
' A further object is to provide a method of the character f described which is well suited to high speed,'commercial production.
Numerous other objects and advantages of the'invenaccompanying drawings, discloses a preferred embodiment thereof.
Referring to the drawings: FIGURES 1 through 5 are side elevafional views in section showing the sequency of steps in sealing an end I closure to the body of a paper cup.
FIG. 6 is a fragmentary enlargedview in section showing an end seam formed by the steps illustrated in FIGS.
' 1 through 5. FIGS. 7 and 8 are fragmentary enlarged views in section similar to FIG. 6 but showing modified end seam constructions. g
The preferred or exemplary embodiment of the instant Ition will be apparent as it is better understood from the following description, which, taken in connection with the ice invention illustrated in the drawings shows a frusto-conical paper body 10 having a larger diameter end 11 and a smaller end 12. Disposed within the body 10 and spaced from end 12 is an end closure member generally designated 13 comprising a flat portion 14 extending transversely of the body 10 and, a downturned peripheral flange 15 (FIG. 1). Although extending generally downwardly towards the smaller diameter end 12, the flange 15 also flares radially outwardly so as to make peripheral contact with the inside of the body 10. This flare of the flange 15 has been found advantageous in providing intimate contact between the outer surface of the flange 15 and the inner surface of the body 10 when the closure 13 is in its lowermost position adjacent the end 12 and in minimizing the buckling of the closure 13 as it is lowered into position adjacent the smaller diameter 12. On the interior surface of the body 10, on the surface of the portion 14 facing away from end 12 and on the surface of the flange 15 facing the side wall of body 10 is a coating of polyethylene 17 (FIG. 6).
With the body 10 and closure 13 maintained in the above described position, hot air ejected or blown through two series of orifices 18, 19 arranged concentrically in a head 20 is impinged against the inside and outside of the body 10 at its smaller diameter end 12. The jets blowing or emerging from the orifices 18 impinge against the inside of the body 10 whereas the jets coming from the orifices 1'9 strike against the outside of the cup body 10. The hot air is transmitted to the head 20 from a suitable source thereof (not shown) through a pipe or conduit 21. By virtue of the barrier presented by the radially outward 1y flaring flange 15, the polyethylene coating on the upper side of flange 15 does not have any hot air impinged directly thereagainst. However, because of the proximity to the hot air jets and the generally heated atmosphere within the more or less enclosed space at the bottom of the cup, heat is transferred through the paper of the flange 15 to the polyethylene on the upper surface of the flange. The jets of hot air are impinged directly against both the inside and outside of body 10 to raise the polyethylene coating 17 to the desired temperature in a minimum of time. The impinged hot air acts to heat the polyethylene coating adjacent the end 12 of body 10 to at least a softened, if not tacky, state. It is to be understood that if a slower speed (although still relatively fast) operation could be tolerated, the air jets impinged against the outside of the body 10 could be dispensed with. In other words, it is essential only that the jets of hot air be im-' pinged against the polyethylene coating 17 'on the inside of the body 10. a
After the polyethylene coating 17 on the body10 has beenbrought to the desired heated or tacky condition, the closure 13 and body 10 are moved longitudinally relative to one another to position the closure 13 closer to or adjacent the smaller diameter end 12 (FIG. 3). In this position, the outer surface of the flange 15 is in contact with the heated polyethylene on the inside surface of the body 10; the portion 14 being spaced from the end 12 a distance approximately equal to twice the length of the flange 15. With the closure 13 thus positioned, jets of hot air are again directed towards-the inside and outside surfaces of-the body 10 contiguous its be discontinued during the repositioning of closure 13 and thereafter recommenced after-the closure is in its-new position. Further, as with the initial impingement of hot air described above, impingement of the hot air against the outside *ofgthe body *10 may be omitted if desired.
while-the polyethylene coating is in its heated, tack-y state, the peripheral margin of the end 12. is folded inwardlyaround the peripheral flange 15 such as by a die 22 as shown in FIG. '4. Thereafter, the inturned peripheral marginris ironed flat against-the adjacent portion "of the body 10 with the Jflange 15 disposed therebetween. This operation may be accomplished by any suitable means,such as by a 'pair of opposed rollers 23, 24. By virtue of the tacky polyethylene on the inner surface of the body 10, and the outer surface of the flange 15 a strong, permanent, moisture-proof seal between the end closure'13 and thecup body is effected. Further hecause the polyethylene coating 17 extendsover the entire inside surface of the body 10,and over the inside'surface of the-closure 13,and because there are no raw edges exposedon'theinside of the cup, the paper in the finished cup as shown in FIG. 5 is completely protectedfrom at- 'tack by liquids, both hot and cold. This protectionmakes the finished cup well suited as a drinking container for foods, such as hot coffee, hot soup, and the like.
FIG. -7 illustrates a modification of the endsea-l. In
':"this modification the lowerextremityo'f the wall of body 10 remains straight-and is not curled inwardly as is the body shown in FIG. 6. Also, in this modification, the
down-turned flange is adhesively secured to the straight body wall contiguous the :end 12 with the periphery of the flange 15 exposed. The same operations shown in FIGS 2, 3-and -5 are performed to produce a cup having this modified construction. The folding in operation "shown in :FIG. 4 is omitted since, in the modification 1 shown in FIG. 7, the body wall is notturned inwardly.
FIG. 8 illustrates another bottom searnmodification. 'In this modification the lower marginof the bodyltl'is turned inwardly as with the body in FIG. '6 but the flange 15 extends upwardly rather than downwardlyas shown in FIG. 6. The inturned margin of the body 110 forms, in effect, a circumferential shelf upon which the closure 1'3 rests. The-operationalsteps .to'forrn this :con-
struction are-the same as those shown in FIGS. 1 through 4 except that the flange 15 is turned upwardly instead of downwardly. Any suitable means may be used to iron the contiguous surfaces of the seam flat and form the "necessary adhesive seals, such as (shown .in dot-dash lines) the roller 25=contactingthe outside of thecnpand ro'llers 26, 27 'contacting'the curled peripheral margin and the flange 15 respectively. Theroller 27 should'be :made of some heat resistant, non-adherent material such "as Teflon so "it will not stick to the heated polyethylene on the flange 15.
It is to be understoodth'at materials other than polyethylene may -be used as the adhesive in the instant invention. In general, any hot-melt adhesive is operable in the present invention if it reaches its activated state in a time and at a temperature which is nondestructive to'the paper to which it is-a'pplied. Examples ofother h'ofimelts are polypropylene, "vinyl resins and polyamide resins.
resins withintheseibroad classes will be readily apparent' toithose skilled in the art.
Other operable hot-melts and specific adhesive "Itis readily apparent that the method of "heating used in the instant invention "involvingjets or hot air effec- :tively 'suppliesheat fto the polyethylene orother adhesive coating on the surfaces of. the container to be bonded; yand obviates the difliculty involved with the use of heated tools, such as dies and chucks. Because a mobile, fluid stream of hot air is used to supp ly the heat to the necessary parts of the container, heat sealing containers having irregular shapesor at least, shapes .very difiicult to reach with tools such as thenarrow opening and tapered con- 4 struction of the container described hereinbefore presents .no problems. Further, impinging the hot air directly onto the surfaces to be heated raises these surfaces to the necessary temperature in a minimum amount of time,
much more rapidly and economically than could be accomplished by other means, such' as infra red heaters.
.It is thought that the invention and many of its attendant advantages will be understoodfrom theforegoing description, audit will be apparent that various changes may be made 'lil'l the :steps of the :methoddescribed and their order of accomplishment without departing from the spirit and scope of the invention or sacrificing all of its material advantages, 'the method hereinbefore "described being'merely a preferred embodiment thereof.
I. A method of joining a closure having a peripheral flange to a frusto-conically shaped'body' tcfformian'open ended paper container comprising, positionin'gisaid closure within and transversely of said-bo'dy-andspacedfrom the end thereof having the smaller Ldiameter with said peripheral flange extending toward said smaller diameter end thereby forming a cavity-like hollow at said end,
the inside surface of said body and the surface of said flangeadjacent said insideisurfaceihaving arpolyethylene coating thereon, blowing hot air 'into 'saidh'ollow and against the inside surface of said 'body adjacent said smaller diameter end and simultaneously therewith against the outside surface of said body adjacent said smaller diameter end to soften said polyethylene "coating on this portionofsaid body, moving said closure toward said smaller diameter end to anew position adjacentsaid smaller diameter end thereby forming a cavity-like hollow at said end smaller than said first mentioned hollow, continuing the blowing of hot air into said smaller hollow and against said body and against said flange'to render the polyethylene thereon tacky and as,
endythe inside surface of said body contiguous said smaller end having a thermoplastic adhesive .thereon, blowing hot .air intosaid hollow and against said adhesive to heat said adhesive, moving said closure to ward said smaller end to a new position adjacent said smaller end with "said flange portion contiguousand in substantial parallelism. with the inside surface of said body and with said heated adhesive disposed between said flange portion and said inside surface thereby forming a cavity-like hollow at said smaller end smaller than said first mentioned hollow, continuing the blowing of hot air into said smaller hollow and against said flange portion to soften and. tac kify said adhesive, and pressing said flange portion and-said body together with said softened tacky adhesive therebetweento firmly bond said closure tosaid body.
3. The method set forth in claim 2 wherein both .the
outside surface of said flange ,portion .and the, inside I 'surface of said body have a thermoplastic adhesive thereon. 1
4. The method set forth in claim 2 wherein said hot air is blown against both the outside and inside "of said body contiguous 'said one-end thereof.
5. The method-set forth in claim 2- whereinsaidbody has-a .circular cross section.
(References. on following page) References Cited in the file of this patent UNITED STATES PATENTS Blixt Mar. 10, 1931 Widell Aug. 15, 1939 Hubner et a1. Aug. 19, 1941' Maas et a1. Oct. 14, 1941 6 Haslacher July 1, 1947 Steinkraus Nov. 9, 1948 Majer Aug. 13, 1957 Quandt May 6, 1958 FOREIGN PATENTS Great Britain June 3, 1953