Note: Descriptions are shown in the official language in which they were submitted.
lU~ SO
FIELD_OF THE INVENTION
Providing containers comprising membrane-type
closures having integral tabs which may be grasped to enable
removal of the closure.
` BACKGROUND OF THE INVENTION
Various aspects of providing containers having
membrane-type closures, and of induction heat sealing membrane-
type closures to containers are disclosed in prior art U. S.
patents of which the following are representative: U. S. Patent
No. 2,937,481 issued May 24, 1960 to Jack Palmer; U. S. Patent
No. 3,460,310 issued August 12, 1969 to Edmund Philip Adcock --
et al.; U. S. Patent No. 3,501,045 issued March 17, 1970 to
Richard W. Asmus et al.; U. S. Patent No. 3,734,044 issued May ~ -
22, 1973 to Richard W. Asmus et al.; U. S. Patent No. 3,767,076
issued October 23, 1973 to Leo J. Kennedy; U. S. Patent No.
3,805,993 issued April 23, 1974 to William H. Enzie et al.;
and U. S. Patent No. 3,808,074 issued April 30, 1974 to John
Graham Smith et al. However, the prior art does not disclose
solutions to all of the problems associated with providing
containers having membrane-type closures in the manner of or
degree of the present invention.
OBJECTS OF THE INVENTION
The nature and substance of the invention will be
more readily appreciated after giving consideration to its
major aims and purposes. m e principal objects of the
invention are recited in the ensuing paragraphs in order to
provide a better appreciation of its important aspects prior
to describing the details of a preferred embodiment in later
portions of this description.
A major object of the present invention, in one aspect,
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1063~i50
is to provide a thermoplastic overcap comprising heat-deformable
means for causing the peripheral section of a heat-se~lable
membrane-type closure to conform radially and circumferentially
to the rim of a container body when the closure is heat sealed
to the rim of the container body.
A major object of the present invention, in another
aspect, is to provide a container subassembly comprising a
composite tubular body and an asymmetrical shape membrane-type
closure having an integral pull tab and means for induction
heat sealing the closure to the body to effect a hermetic seal
therebetween.
Another object of the present invention in a further
aspect is to provide a hermetically sealable container sub-
assembly comprising a spirally wound composite tubular body, and
an asymmetrical shape membrane-type closure having an integral
pull tab.
Still another object of this aspect of the invention
is to provide the container subassembly described in the pre-
ceding paragraph which subassembly comprises means for being
induction heat sealed.
A further object of the present invention is to provide
the container subassembly described in the preceding paragraph
which container further comprises an overcap having heat-
deformable means for causing the peripheral section of the
closure to conform radially and circumferentially to a rolled
rim of the tubular body.
A still further object of the present invention, in ?
another aspect, is to provide a method of induction heat sealing
an asymmetrical shape membrane-type closure to the rim of a
tubular container body so that the peripheral section of the
closure conforms radially and circumferentially to the rim of
the tubular body.
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According to one aspect of the invention there is
provided a container subassembly comprising
a membrane-type closure, a composite
tubular body having an outwardly rolled top rim, and heat
activatable sealant and electrical insulation means disposed :
intermediate said closure and said rim of said body, said
closure comprising an electrically conductive sheet which is
configured to provide a disc portion and an integral radially --.
extending tab, said tab being folded so that it extends
~ 10 radially inwardly from the perimeter of said disc portion ~-
and is disposed superjacent the top surface of said disc ..
: portion, said body comprising a liner formed from a web of
electrically conductive material which is spindled into a
tubular shape so that oppositely disposed side edge portions
are sealingly secured together in overlapped relation to form
a body seam, and said closure being sealingly secured by said
heat activatable sealant to said rim along a circumferentially
extending seam with said electrical insulation means disposed
therebetween so that the peripheral section of said disc
20 portion conforms radially and circumferentially to an upwardly
facing annular-shape area of said rim. This aspect of the
invention is disclosed and claimed in Canadian Patent Application
No. 231,277 of C.L. Johnson et al, filed July 11, 1975, of
which the present application is a divisional. (Said
Canadian Application No. 231,277 is now Canadian Patent No.
1,043,292, granted November 28, 1978).
This aspect of the invention further resides in a
container subassembly comprising a body having a top rim, a
membrane-type closure, an overcap, and means for heat sealing
30 a peripheral section of said closure to said rim along a
circumferentially extending seam when heated to a predeter-
mined temperature, said overcap comprising heat-deformable
means for
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~063~50
uniformly distributing a biasing force from a planar
surface to a uniformly bias the peripheral section of said
closure against said rim when said heat-deformable means is
heated to said predetermined temperature whereby the peripheral
section of said closure is caused to conform radially and
circumferentially to said rim and to be sealingly secured
thereto upon applying said biasing force while heating said
section, rim, and heat-deformable means to said predetermined
temperature, and then cooling said section, rim, and heat-
deformable means to a sufficiently low temperature to setsaid circumferential seam while maintaining said biasing force.
Said container subassembly is described and claimed in the
aforementioned Canadian Patent No. 1,043,292.
The present invention, in another aspect, resides in
a thermoplastic overcap for a container subassembly comprising
a tubular body having an opening defining-rim and a membrane-
type closure, said overcap comprising a top panel and an annular
skirt depending from the periphery of said top panel, said top
panel comprising heat-deformable means for causing the peripheral
section of said closure to conform radially and circumferentially
to said rim when said overcap is biased towards said rim by a ' - -
. , .
biasing device presenting a planar surface to the exterior of : :
said top panel while said heat-deformable means is heated to a
sufficiently high temperature to effect said conformation, ~ :
said heat-deformable means comprising a multiplicity of
circumferentially spaced, radially extending, depending
integral ribs of thermoplastic material disposed adjacent ~: .
the perimeter of said top panel so that said ribs overlie ~ ~-
said rim when said overcap is applied to said container
subassembly.
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According to a further aspect of the invention there is
provided a method of induction heat sealing an asymmetrical-
shape closure to a tubular body having an outwardly rolled top
rim with electrical insulation means disposed intermediate
said closure and said rim, said closure comprising a disc
portion and an integral radially extending tab, said tab being
folded upwardly and radially inwardly so that it lies super-
jacent the top surface of said disc portion, said closure
- comprising an electrically conductive sheet, said body comprising
an electri~ally conductive liner, said method comprising the
~` steps of:
a. juxtapositioning said closure on said rim with
said electrical insulation means disposed intermediate the
bottom surface of the peripheral section of said disc portion
and said rim,
b. biasing said peripheral section towards said rim
- with a uniformly distributed force,
c. simultaneously subjecting adjacent portions of
said electrically conductive sheet, electrical insulation
.
means, and said electrically conductive liner to a high
frequency electrical field of sufficient constant intensity
to independently inductively heat said adjacent portions of
said sheet and said liner to cause heat activatable sealant
disposed intermediate said adjacent portions to be conductively ~-
heated to a sufficiently high bonding temperature to sealingly
secure said adjacent portions together along a circumferentially
extending seam,
d. terminating said field to enable said sealant
to cool to a sufficiently low temperature to set said seam, and
e. terminating said biasing.
This aspect of the invention is claimed in Canadian
Application No. 300,649 filed April 7, 1978, which is another
divisional of said Canadian Application No. 231,277 (now
Canadian Patent No. 1,043,292).
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~RIEF DESCRIPTION OF T~IE Dr~ IN(~S
While the specification concludes with claims
particularly pointing out and distinctly claim.ing the
subject matter regarded as f~rming the present invention, it
S . is believed the invention will be better understood from the
- following description taken in connection with the accompanying
drawings in which:
Figure 1 is an exploded perspective view of a
preferred container subassembly embodying the present invention.
-Figure 2 is a -fragmentary perspective-~i-ew af the
container subassembly shown in Figure 1.
Figure 3 is an enlarged scale, fragmentary perspective
view of the spirally wound and lap seamea liner of the container
subassembly shown in Figures 1 and 2.
Figure 4 is a fragmentary sectional view of the liner .
shown in Figure 3 taken along line 4-4 th~reof. ~
Figure 5 is a fragmentary, radial~y outwardly looking ,.
view of the liner-seam-area of the outwaraly rolled rim of the
tubular container body shown in Figure 1.
Figure 6 is an enlarged scale bottom view of the
overcap of the container subassembly shown in Figure 1.
; Figure 7 is an enlarged scale, fragmentary radial
sectional view of the overcap shown in Figure 1 taken along line
7-7 thereof. ~.
Figure 8 is an enlarged scale fragmentary circum-
. ferential sectional view of the overcap shown in Figures 1, 6
and 7 taken along line 8-8 of Figure 7.
Figure 9 is an enlarged scale top view of the
membrane-tvpe closure shown in Figure 1 prior to folding the
integral tab of the closure to the orientation shown in Figure 1.
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Figure 10 is a fragmen,ary sectional view of the
closure shown in Figure 9 taken along line 10-10 thereof. -
Fiqure 11 is an enlarged scale radial sectional
view of a top edge portion of the container subassembly
shown in Figure 2 taken along line 11-11 thereof which line
l extends between radially extending ribs depending from the
i interior surfa~e of the overcap of the subassembly.
I Figure 12 is an enlarged scale circumferertial
~-! sectional view of the container subassembly shown in Figure 2 taken along line 12-12 thereof.
Figure 13 is a reduced scale,end view of a portion
of an apparatus for induction heat sealing the closure of the
container asse~bly shown in Figure 1 to the rim of the tubular
body of the container assembly.
Figure 14 is a re~uced scale perspective view of the
induction heating electroae of the apperatus shown in Figure 13.
Figure 15 is a fragmentary perspective vie~ of an -
alternate cortainer subasser~ly embodying the present invention.
Figure 16 is ar. enlarged scale to2 view of an
alternate membrane-type closure which may be incorporated in
container subassemblies embodying the present invention.
Figure 17 is an enlarged scale, fragmentary top view
of another alternate ~embrane-type closure which may ~e incor-
porated in container subassemblies embodying the present invention
2S - Figure 18 is a sectional view of the alternate
membrane-type closure shown in Figure 17 taken along line 18-18
thereof.
Figure 19 is an enlarged scale, fracmentary top view
of yet another alternate mer~rane-type closure which r,ay be
incorporated in container assem~lies embodying the prcsent
invention.
(Figures 16-19 inciusive are located in the second
sheet of drawings, together with Figures 7-10.)
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DESCRIPTION OF T~E PREFEP~RED ~!`5BODlr~.MT
__
Referring now to Figures 1 and 2, the preferred
embodiment of the present invention is a container sub-
assembly 40 ~hich comprises a spirally ~ound, composite
tubular body 41, a membrane-type closure ~2 having an
integr21 pull t2b 43, and an overcap 44. - ~
Briefly, overcap 44 comprises heat-deform2ble
means such zs ~ multiplicity of circumferentially spacea,
radially extending ribs 85 (See Figs. 6, 8 and 12) which
means are heat-deformed
` 10 or molded when container sub2ssembly 40 is assembled to cause
the peripheral section of closure 42 to conform radially and
circumferentially to the rim of tubular body 41 regardless of -:
- minor irregularities in the rim of tub~lar body 41. Further,
~ the container subassembly comprises means for induction heat
; 15 sealing closure 42 to the rim of tubular body 41 and for causing
the heat-deform2ble means to effect the above described radial :~.
and circumferential conformation of the peripheral section of
closure 4 to the rim of tubular body 41. ~:.
: Tubular boay 41, Figure 1, of the preferred embodiment
container assembly 40 is a glue bonded, composite, spirally
- wound tub-e construction which tube, after being cut to length,
~- has its top rim 48 rolled outwardly to form a circumferentially
: extending bead and has its bottom rim 49 flared to enable
crimping a botto~ closure thereto.
Referring now to FiGure 11, the multi-ply sidewall
of tubular body 41, Figure 1, is shown to comprise three ~ajor
plies: an innermost ply hereinafter referred to as liner aO,
an outermost ply hereinafter referred to as label 51, and a
~iddle ply 52. In the preferred em~odiment cor.tainer asse~bly
4D, Figure 1, label 51 comprises fifty-five pound litho paper
.
106;~5~0
c~ated with a moisture barrier whi~h, in turn, is printed
and coat~d with an overprint lacq~er; and the middle ply 52
is nineteen point kraft paper can board.
~iner 50, Figure 3, comprises a web of four layer
- -5 constr~ction as shown in Figure 4. The innermost la~er 53 is a
- thermoplastic material which forms the radially inwardly facing
portion of body 41 when the web is spirally wound and spirally
lap seamed as indicatea in Figure 3. The thermoplastic
~ material of the preferred embodiment is a twelve pound coating
`` 10 of Surlyn, DuPont number sixteen-hundred-fifty-two S~, an ionomer
resin, although polypropylene and other the~moplastic materials
may be used. Surlyn is a registered trademark of the E.I. DuPont
de Nemours Company. The second layer 54 is aluminum foil having
a preferre~ thickness of about thirty-five one-hundred-
thousandths of an inch which is adhered to the outermost layer
56 by the third layer 55 of the construction which third layer
may be a seven pound coating of low density polyethylene. The
outermost layer 56 may be twenty-five pound machinè finish
natural kraft paper.
~i 20 When the web from which liner 50 is spirally wound
into the tubular shape shown in Figure 3, one side edge portion
60 is doubled back so that the oppositely disposed second side
edge portion 61 can be overlapped therewith with the thermo-
plastic innermost layer 53 of side edge portions 60, 61 in
- 25 abutting relation. This enables the overlapped side edge portions
60, 61 to be heat sealed together to form a spiral lap seam
or body seam 62 h2ving a spiral inner edge 63 and a spiral
outer edge 64.
As is shown in Figure 3, spiral lap seam 62 comprises
three thicknesses of the web from which the liner 50 is fo-med.
The two extra thicknes~es of liner material in spiral seam 62
precipitate a circumferentially extending hump 65, Figure 5,
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in the top rim 48 of tubular body 41, which hu~p 65 is
~;ho~,~n in ex2ggerated proportions in Figur~ 5 to more clearly
disclose that it causes the top rim 4 8 to have elevational
differences around the top opening 66 of tubular body 41 as
S indicated in Fiaure S by delta E; (~ E ~
As will be described more fully hereinafter,
elev2tional differences of rim 48 around top opening 66 ~hich
differences are precipitated by lap seams and/or other aspects -
of making spirally wound composite tubular bodies such as 41
having outwardly rolled top rims re~uire special atten.ion to
- hermetically seal a membrane-type closure such 2S closure 42 to
the top rims
The membrane-type closure 42, Figure 9, has an
asymmetrical shape, and comprises a disc portion 70 and an inte-
gral radially extending tab 43 having its proximal end 71 hinged~
secured to the peri~eter 72 of disc portion 70 An annular-
shape section of disc portion 70 which extends radially inwardly
from perimeter 7Z is designated peripheral section 73
As shown in Figure 10, closure ~2 is a three layer
construction comprising a top layer 74, a middle layer 75,
and a bottom layer 76 In the preferred embodiment closure 42,
middle layer 75 is an electrically ~onductive sheet of type 1145-;--
aluminum having 2 nominal thickness of about three
mils, top layer 74 is a one-half pound vinyl washcoat such as
"Adcoat ilC"* available from Morton Chemical Company, Chicago,
Illinois, and the bottom layer is a one mil thermcplastic
coating of DuPont type XBR 950 ethylene vinyl acetate The
vinyl washcoat is provided as a means for protecting the top
surface of the al~inum sheet from oxida.ion, and the XBR 950
coating is provided o~ the bottom surface of the aluminum sheet
to m2~e the peripheral section 73 of closure 42 peelably heat
*Trademark
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sealable to an upwardly facing annular-shape area of the
thermo?lastic innermost layer 53 of liner 50 of tubular body
41 which layer 53 is disposed on the top of rim 48 by virtue
~ of rim 48 being rolled outwardly a_ described hereinbefore.
Together, the portions of the XBR 950 coa,ins and
the thermopl2stic layer 53 of the liner 50 of tubular body- -
41 comprise electrical insulation means and heat activatable
sealant disposed intermediate the aluminum sheet 75 of closure 42 and
the aluminum layer 54 of liner 50 whereby the peripheral section
L0 73 of closure 42 is susceptible to being induction heat sealed
to the top rim 48 of the tubular body 41 to form a hermetic
circumferential seam therebetween.
Overcap 44, Figure 1, of the preferred embodiment
is made of thermoplastic material such as low density poly-
S ethylene resin type 1400 available from Gulf Oil Chemicals Co.,
Orange, Texas. Overcap 44, Figures 6 and 7, comprises a top
panel 80 and an annular skirt 81 depending from the periphery of
the top panel 80. ~ -
; The top panel further comprises an annular-shape
;0 stacking flange 82 which extends upwardly from the exterior sur-
face 83 of top panel 80. The stacking flange ~2 has a planar,
annular-shape top surface 84. The stacking flange 82 has a mean
diameter subst2ntially e~ual to the mean diameter of rim 48
of container body 41 so that the stacking flange 82 is super-
jacent the rim 48 when the overcap 44 is applied to the tubular
body 41 as shown in Figures 2 and 11.
; The top panel 83 of overcap 44 also comprises heat-
deformable means such as a multiplicity of circumferentially
spaced, radially extending ribs 85, Figures 6, 7 and 8, ~hich
o depend from the interior surface of the top panel 80 of overc2p
44. The ribs 85 2re so disposed that they underlie the stacking
--10--
l(~ti3~50
flang~ 82 whereby they radially span the rim 48 of the tubular
body 41 when the container su~assembly 40 is assembled as shown
in Figure 11. Figure 7 is a radial sectional view taken between
two ribs 85 to.show the radially extending profile of a rib 85 ~ .
S and Figure 8 is a circumferential sectional view taken through
- the ribs 85 to show their transverse cross-sectional shape.
Such heat deformable means as ribs 85 are provided to cause
the peripheral section 73 of closure 42 to conform radially
and circumferentially to the rim 48 of tubular body 41 by being
heat-deformed ~en the container subassembly 40 is assembled as
shown in Figures 11 and 12. In the preferred embodiment, ribs
85 have a radial length L, Figure 7, of about one-quarter of
one inch, a width W, Figure 8, of about six-thousandtns of one
inch, are spaced circumferentially about ten-thousandths of one
~5 inch center-to-center, and have a height H, Figure 8, of about
eight-thousandths of one inch.
. The annular skirt 81 of overcap 44 comprises means
for cooperating with overcap engaging means provided on the
- tubular body 41 adjacent the top rim 48 of the body 41. In the .
preferred embodiment, the radially inwardly and downwardly
extending shoulder 87 comprises the means for cooperating with
overcap engaging means on the t~bular body 41,.and the radially
outwardly disposed, radially inwardly and downwardly extending
distal portion 88 of the outwardly turned top rim 48 of tubular
body 41 comprises such overcap engaging means, all as shown in
Figure 11.
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The container subasse~bly 40, Figures 1 and 2 is
assembled as shown in the greatly enlarged scale radial sectional
view of Figure 11 taken along line 11-11 of ~igure 2, and as
shown in the greatly enlarged scale circumferential sectional
view of Figure 12 taken along line 12-12 of Flgure 2. Briefly,
the preferred methcd of so assembling container subassembly 40
comprises biasing the overcap 44 towards the rim 48 of the tubular
body 41 while adjacent portions of the peripheral section 73 of
closure 42, rim 48, and ribs 85 are simultaneously heated by
induction heating means to a sufficiently high temperature to heat-
deform the ribs 85 to cause them to evenly distribute the biasing
. ._, .
force across the closure-rim interface to cause the peripheral g
section 73 of closure 42 to conform radially, Figure 11, and ~-
circumferentially, Figure 12, to rim 48 as shown, and to be
hermetically sealed thereto along a circu~ferentially extending
seam 89. By virtue of heat-deform-ng ribs 85 as shown in Figures
: 11 and 12, the peripheral section 73 of closu~e 42 can be made to
so conform to rim 48 regaraless of elevational differences
~ caused by the seam 62 of the liner 50 (i.e.: hump 65, Figure
-~20 5), or the presence of tab 43, Figure 12.
. Preferably, the biasing force is applied from a
planar surface 95 of a biasing device such as spring 96 incor-
porated in an induction heating device 97 to the planar surface
- 84 of overcap 44 as shown in Figure 13 while carriage 98 is
-:25 drawn along cylindrical guides 99, 100 by a chain 101 attached
~, to the carriage 98 is drawn around a driven sprocket 102. By
virtue of shafts 103, 104 being freely rotatable in the upstand-
ing ends 105, 106 respectively of carriage 98, and by virtue of
a pinion gear 107 being drivingly secured to shart 103 and
~30 drivingly engaged with a stationary rack gear 108, à loosely
assembled container subassembly 40 can be supported between
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cups 109,11o, and rolled past the non-contacting linear
sections 111, 112 of induction heating electrode 113, Figure 14, -
as the carriage 98 is moved. As shown in Figure 13, linear
section 111 of electrode 113 is disposed substantially tbut
not touching) tubular body 41 subjacent the top rim of the body,
and the linear section 112 of electrode113 overlies the overcap 44
and closure 42 radially inwardly from the rim of the body and
extends chordally-with respect to the rim. Thus, by energizing
~electrode 113 by a suitable RF source (not shown) adjacent
portions of the-elect-rically conducti~e sheet ~5 of -closure 42
- and the electrically conductive layer 54 of liner 50 can be
. . .
simultaneously induction heated whereby adjacent portions of
. . . :
the ribs 85 of the overcap 44, the thermoplastic coating 76 ~
~ .
of closure 42, and the thermoplastic innermost layer 53 of
liner 50 are simultaneously conduc'ively heated. When thus
heated to a sufficiently high temperature, the biasing force
will precipitate the above described radial and circumferential
conformation, and the hermetic circumferential seam 89 will be
formed.
Ribs 85a, Figure 12, illustrate the heat-deformation
of the ribs which causes the biasing force to be equally dis-
tributed around the peripheral section 73 of closure 42 during
the induction sealing operation described above. Were the
tabs 85a disposed superjacent the tab 43 not so deformed, the
biasing force would be concentrated in the tab area. This
concentration of bias might precipitate damage to the underlying
` portion of rim 48 and/or reduce the bias around the remainder
of the rim to a value too low to effect good sealing.
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The Model 5000 R.F.C. High ~'requency Generator which
is available from the Radio Frequency Compar.y, 44-46 Park Street,
Medfield, Massachusetts is such a suitable RF source referred
to above.
S During the assembly and sealing of the preferred con-
tainer subassembly described hereinabove which subassembly 40
comprises a tubular body 41 having an inner diameter of about
two-and-seven-eighths inches, the R.F.C. Generator was operated
- at a plate cu-rent of about one-and-three-tenths amperes, a spring
biasing force of about thirty pounds was applied, and the carriage
was drawn past the linear sections 111, 112 of electrode 113 at
about two feet per second. The linear sections 111, 112 of
electrode 11' were approximately twelve inches long.
.. . .
During such induction heat sealing as described above,
~15 and with the tab 43 of the closure 42 oriented away from *he
seam 62 in liner 50 of body 41 as shown in Figures 1 and 2,
the maximum temperature achieved under the proximal end 71
of tab 43 was in the range of from about two-hundred-thirty to
about two-hundred-thirty-nine degrees Fahrenheit while the
maximum temperature achieved around the rest of the rim 48
was in the range of from about two hundred-seventy to about
two-hundred-seventy-nine degrees Fahrenheit.
.
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io~s~
The tensile streng~h of the peelable bond achieved
between XB~ 950 and Surlyn ~registered tradem2rk of the DuPont
Company) or ~olypropylene is directly related to the tempera-
ture achieved during the heat sealing operation. Thus, because
S the maximum temperatures achieved under the proximal end 71
of tab 43 and above the body seam 62 in the rolled rim of
body 41 were lower than in the remainder of the circumferential
seam 89, it follows that the tensile strength of the circumfer-
ential seam 89 is smaller under the tab 43 and above the body
seam 62 than in the remainder of the~circumferential seam 89.
- However, in similar subassemblies wherein either -
the electrically conductive sheet is omitted from the closure
or the electrically co~ductive layer is o~itted from the
tubular body, the tensile strength of the circumferential seam
is, as compared to the preferrea embodiment container sub-
; assembly, inferentially, much lower as witnessed by the following
examples.
;~ When a container subassembly like the preferred
embodiment but for omitting the electrically conductive sheet
~20 from the closure was subjected to the -ealing conditions
described hereinabove, the maximum temperature achieved
.
; intermediate the peripheral section of the closure and the
rim of the tubular body was in the range of from about one-
hundred-twen'.y to about one-hundred-twenty-nine degrees
.
Fahrenheit; less than one half that achieved in the preferred
embodiment. ;
Similarly, when a container subassembly like the
; preferred embcdiment but for omitting the electrically con-
ductive layer in the rim of the tubular body was subjected to -
the same sealing conditions, the maximum temperature achieved
~ . .
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under the pro~imal end of the tab was in the range of
from about one-hundred-ten to about one-hundred-nineteen
desrees Fahrenheit and the maximum temperature in the
circumferential seam area spaced a~lay fron the tab and the
S body seam was in the range of from about one-hundred-thirty
to about one-hundred-thirty-nine degrees Fahrenheit; also
less than about one half that achieved in the preferred
embodiment.
From the foregoing, it is clear that both the
,10 electrically conductive sheets in the closure 42 and theelectrically conductive layer in the liner of tubular body
41 are required to enable inductively sealing those members
of the sub~ssembly together in the manner described herein-
before. Also, by virtue of making the electrically conductive
sheet and layer of aluminum, the resulting cont~iner subassembly
is subject to being hermetically sealed by crimping a suitable
hermetic closure to the bottom end of the tubular body. However,
the electrically conductive mem~ers must be electrically insulated
from each other to prevent arcing during induction heating.
.~' ' , .
Referring now to Figure 15, an alternate container
subassembly 40a is shown which comprises the same tubular
body 41, closure 42, and overcap 44 as the preferred container
subassembly 40, Figures 1 and 2. Indeed, the subassemblies
40 and 4ba are identical but for the fact that closure 42 of
subassembly 40, Figure 2, is oriented with respect to the
rim of the tubular body 41 so that the proximal end of the
tab 43 is not disposed superjacent the portion of the lapped body
seam 62 disposed in the rim of the tubular body in the preferred
assembly 40, whereas the closure 42 of subasse~bly 40a, ~igure
~0 15, is oriented with respect to the rim of the tubular body
. .
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41 so th2' the proximal end of the tab 43 is disposed supe~-
jacent the portion of the lapped body seam 62 of the tubular
b~dy 41 disposed in the rim 48 of the tubular body in the alter-
. nate container subassembly 40a.
. , .
.5 As will become apparent from the.. following
example, the circumferential seam 89, Figure ll, of pre-
ferred e~bodiment container subassembly 40, Figures 1 and
2, has greater structural integrity than the circu~ferential
seam in the alternate subassembly 40a, Figure 15. However,
10 because the tensile strength of the circumferential seam sub-
jacent tab 43 of subassembly 40a is less than in subassembly
. 40, the initial pull re~uired to begin peeling closure 42
from the tubular body 41 is commensurately less. Therefore,
~ a container comprising subassembly 40a is easier to open than
.15 a container comprising subassembly 40 and for that reason
-;- more desirable for some container applications than a container
.; comprising a subassembly 40.
The reduced initial pull required to peel a closure
. from an alternate container subassembly 40a, Figure 15, is inferred
.20 from the fact that when such an as~embly is subjected to the -ame
: sealing conditions described in con3unction with the preferred .
embodiment container subassembly, the maxim~ temperature .
achieved subjacent the proximal end of the tab of the closure
is in the range of from about one-hundred-seventy to about one-
hundred-seventy-nine degrees Fahrenheit, wnile the ma~imum
~` . temperature achieved in the remaining portion of the circum-
ferential seam is in the range of from about two-hundred-
. seventy to about two-hundred-seventy-nine degrees Fahrenheit;
over twice the differential measured in the preferred container
assembly 40, Figures l and 2, as set forth hereinabove. Indeed,
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the pull required on the tab of the closure to initiate peeling
the closure from the preferred embodiment 40 is greater than
two times that required for the alternate container ~ubassembly
40a.
Referring now to Figure 16, an alternate closure
embodiment 42a is shown which has an aperture 120 disposed in
the proximal end 71a of tab ~3a adjacent the disc portion 70a
of the closure. In such a closure having a three-sixteenths-
inch diameter aperture in a one-half-inch wide tab, the .emp-
erature differential experienced between the area under the tab
and the other portions of the circumferential seam during
induction heat sealing was reduced by about twenty-five percent
from the differential experienced in the preferred embodiment
described hereinbefore. Thus, container subasse~blies com-
lS prising the alternate closure 42a would have greater structural
integrity than the preferred embodiment. It is believed that
the benefit of increased structural integrity available
through using alternate closures 42a must be balanced aga-nst
the need therefor and the cost thereof.
. _
2~ Other alternate closure embodiments 42b, and 42c are
shown in Figures 17 and 19 respectïvely. However, the elongate
apertures 121 disposed in the proximal end of the tab are formed
by making C-shape cuts to form flaps 122, Figure 18, and by
folding the flaps 122 as shown in Figure 18. Such a method of
~25 providing apertures obviates scrap removal which would be
-~ required in the manufacture of alternate closures 42a, Figure 16.
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While particular embodiments of the present invention
have been illustrated and described, it will be obvious to those
skilled in the art that various changes and modifications can ~:
. be made without departing from the spirit and scope of the
invention and it is intended to cover, in the appended claims,
all such changes and modifications that are within the scope
of this invention.
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