Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to the Fi]ling and hermetic séal-
ng of plastic-bodied containers with hot liquid or semi-liquid
prod~cts, and in par-ticular to improvements in the methods and
structures for accomplishing same without deforrnation -to the side
wall of the container or prema-ture breaking of the seal.
Recen-tly there has been a demand for a thermoplastic
container for s-toring jams which must be heated -to a liquid or
serni-liquid state at temperatures of up to about l90 F to facili-
tate filling into -the container, and must -then be hermetically
sealed with a heat sealed peelable closure disc. This container
can be used to package foods commonly classified as hot fillable,
such as jams, fruit juices, and o-thers. By ho-t-filling at a
temperature of 190F the container and conten-ts are sterilized
and do no-t require additional preservatives. The higher the tem-
peratures that must be used, -the grea-ter the likelihood of creat-
ing stresses on the container and/or seal because of high in-ternal
vacuums developed upon subsequent cooling of the produc-t, pri-
marily because of the condensation of steam in the head space of
the sealed container. I-t is important tha-t the side wall of the
container be kep-t free of deformation or paneling while at -the
same time maintaining the herme-tic seal to prevent spoilage of the
produc-t during shipping and storage.
In the past it has been known to construct a -thermo-
plastic-bodied container for s-toring motor oils wi-th a flexible
bot-tom so that depletion of gaseous componen-ts causing a change in
the internal pressure can be compensated for by -the flexing action
on the bottom as described in U.S. Patent No. 3,409,167 -to
Blanchclrd. The con-tainer of that patent was formed wi-th a rela-
tively thick side wall and a relatively -thin bottom wall to pre-
vent paneling to -the side wall while permit-ting flexing of the
bottom wall, as set for-th in column 4, lines 3 to lO thereof, for
example. ~
1~9~
~ he present invention provides a hermetical.ly sealed
thermoplas-tic bodied container whi.ch is capable of holding hot
filled produc-ts,such as jams or the like, and which can be easily
opened by simply pee]ing the container closure from the container
body.
The presen-t invention also provides such a container
construc-tion which permi-ts the use of a peelable closure having a
peel s-tren~th which is sufficiently low to permit easy opening by
the consumer, and yet high enough to prevent rupture of the seal
10 when subjected to -the conditions under which the container is
filled and sealed.
The present invention again provides such a container
which is provided with flexible top and bot-tom portions which are
adapted to move inwardly as the hot filled product cools to thus
prevent paneling of the side wall of the container and rupture of
its hermetic seal.
The present inven-tion also improves -the wall construc-
tion of herme-tically sealed thermoplastic containers.
According to the present inven-tion there is provided a
20 hot-filled hermetically sealed gas barrier multi-layer plas-tic
container with a side wall free of deformation having therein a
headspace whi.ch includes moisture vapor, a sterilized ho-t-fillable
food product and a subs-tantial partial internal vacuum, said food
produc-t in the container having a measurable vapor pressure when
hot filled into the container a-t a tempera-ture of up to abou-t
190 F to a level ].eaving a headspace and under conditions suf-
ficient -that there develops measurable moisture vapor pressure in
the container after it is hermetically sealed, and upon cooling
of and consequent condensa-tion of the moisture vapor of the food
30 product, there develops said substan-tail partial internal vacuum
in the container comprising, an open-top plastic body of mul-ti-
layer construction which includes a gas barrier layer substantially
-- 2 --
impervlous to oxygen, said body having: (l) an annular sealing sur-
face about the open top, (2) a bottom wall having a transverse
cross-sectiona] configuration defining means which permits dia-
phragma-tic fl.exing thereof inwardly of said body, (3) a side wall
free of paneling or deformation notwi-ths-tanding said internal
vacuum upon cooling of -the herme-tically sealed hot food product,
(4) said bo-t-tom wall being disposed in an inwardly flexed posi-tion
due -to internal vacuum, and having gradually rnoved to said flexed
position from a more outward unflexed substantially planar initial
lO position located substantially within -the axial leng-th of said
plastic body prior to hot filling and sealing while having coopera-
tively gradually and subs-tan-tially reduced -the substan-tial or high
in-ternal vacuum as it was developing while the hot food product
was cooling, a gas barrier impervious flexibl.e closure disc her-
metically sealed -to the sealing surface by adhesive means defining
with said closure disc and body -the hermetic seal, which withstands
the high internal vacuum which gradually develops upon cooling of
and consequen-t condensation of -the moisture vapor of the product,
withs-tands the subsequent subs-tantially reduced internal vacuum,
20 and yet allows easy peel removal of the disc from the sealing
surface, said closure disc also being disposed in an inwardly
flexed posi-tion due to in-ternal vacuum as allowed by the headspace,
and having gradually moved -to said flexed position from a more
outward unflexed initial position of a subs-tantially flat plane
across said sealing surface while also having cooperatively gradu-
ally and substantially reduced the high internal vacuum as it was
developing, a s-terilized hot-fillable food product in -the con-
-tainer, said food produc-t having a measurable vapor pressure when
hot-filled lnto the container at a temperature of up to about
30 190F after the container is hermetically sealed, and, a head-
space i.n said con-tainer between said food produc-t and the said
closure disc when hermetically sealed, said adhesive means, and
3 --
.'',i~i
said cooperative inwardly flexed positions of said closure disc and
in-tegral bottom wa]l together having coopera-tively substantial]y
reduced or dissipated the high internal' vacuum, and together co-
operatively maintaining -the subs-tantially reduced in-ternal vacuum
in -the container, said side wall unpaneled, said hermetic seal
unruptured, and said closure disc easily peelable. Suitably one of
said layers is a bulk layer formed at least in part from reground
scrap materials of said o-ther layers. PreEerably said adhesive
seal for said closure disc has a T-peel streng-th of from about 3
10 to 5 pounds. Desirab]y said body includes an e-thylene vinyl
alcohol copolymer as a barrier layer. Suitably said closure disc
includes an e~hylene vinyl alcohol copolymer as a barrier layer.
Desirably said side wall is of tapering frustoconical configura-
tion throughou-t a major portion of the axial extent thereof and
merging into a generally cylindrical and substantially vertically
extending rigid pedestal wall of lesser diameter, said pedes-tal
wal] merging in-to said bot-tom wall. Preferably said pedes-tal wall
` is connected to -the frus-toconical side wall by means of an up-
; wardly and ou-twardly angularly extending reinforcing wall, said
20 reinforcing wall ex-tending at an angle of about 45 to -the con-
tainer longitudinal axis and wherein further said frustoconical
side wall includes at its lower end a downwardly and inwardly
curving rounded corner merging into said reinforcing wall. More
preferably the container Eurther includes stacking format~on in said
side wall and permits easily separable nes-ting of a plurality of
empty said plastic bodes.
:[n accordance with -the present invention a uniformly
thick -thermoformed container body made of thermoplas-tic materials
having a plurality of layers including a barrier layer is formed
30 with a lip portion around its periphery to facilitate sealing wi-th
an easily peelable heat-sealed closure disc made of a flexible
flat sheet material after -the con-tainer has been filled wi-th a ho-t
a,
liquld. The bo-ttom wall and the top closure disc of the container
are formed to effect diaphragmatic flexing to relieve the in-ternal
vacuum resultin~ from subsequen-t cooling of the liquid and thus
prevent rupture of the seal or paneling of -the side wall.
The present invention also provides a method for provid-
ing a h.igh gas barrier multilayer plastic conta.iner having a food
product therein and he.rmetically sealed by a high gas barrier easily
peel-openable :Elexible closure, the food product having been hot--
filled at from about 180F to about 190F, the con-tainer being
10 adapted to preven-t the development of high in-ternal vacuum -therein
upon cooling of -the produc-t, hold a reduced internal vacuum and
prevent paneling of the container side walll comprising the steps
of: providing an open--top plas-tic con-tainer body of multilayer
construction which includes a high gas barrier layer, the body
having a side wall extending from its top where it has an annular
~ sealing surface to its bottom where it joins with an in-tegral bot-
; tom wall, the side wall being adapted to resist paneling in res-
ponse to internal vacuum in the con-tainer, and the bottom wall
being adapted co flex inwardly in response to an internal vacuum
20 to prevent the side wall from paneling, providing a flexible high
gas barrier closure disc -to close the container, filling the con-
tainer with a hot foods-tuff which is a-t a tempera-ture of from
about 180F to about 190F and has a substan-tial vapor pressure,
to a level. which leaves an unfilled volume in the container,
promptly herme-tically sealing the open top by bonding the closure
disc to -the seal:Lng surEace in a subs-tan-tially fla-t plane across.
the surface, said disc beiny adapted to :Elex from said plane -to a
more inward pos:ition in response -to an in-ternal vacuum to preven-t
the side wall Erom paneling, said inward flexings of both the bot-
tom wall and closure disc being cooperative -to prevent development
of high internal vacuum upon cooling of -the food product, and co-
opera-tive with the paneling resistant side wall, thereby -to preven-t
- 4a -
inward panel:Lng of the side wall, said sealing of the closure disc
being effected by using an adhesive selected to provide a seal
which is hermetic, will withs-tand -the potentially high internal
vacuum developed in -the container and the inward flexing of the
closure disc, withstand the reduced partial internal vacuurn which
exists subsequent -to the flexings, and ye-t provide easy peel-
opening of the closure disc from the container. Suitably the method includes
the step of providing a bullc layer as one of said layers with said bulk
layer formed at least in part from reground scrap from materials
of said other layers. Desirably the me-thod includes the step of bonding the
the closure disc to the sealing surface-to provide a T-peel strength of from
aboub 3 to 5 pounds per inch. Preferably the method includes the step of pro-
viding an ethylene vinyl alcohol co~1ymer as a barrier layer.
The presen-t invention in one further aspect thereof pro-
vides a method for providing a high gas barrier multilayer plas-tic
con-tainer having a food product therein and being hermetically
sealed by a high gas barrier easily peel-openable flexible clo-
sure, the food product having been filled at a -temperature up to
abou-t 190F under condi-tions sufficien-t -to develop a high moisture
20 vapor pressure in the sealed con-tainer, -the container being adap-
-ted to prevent the development of high internal vacuum -therein
upon condensation of the mois-ture vapor of the produc-t, hold a
reduced internal vacuum and prevent paneling of the container side
wall, comprising -the s-teps of: providing an open--top plastic con-
tainer body of mul-tilayer cons-truc-tion which includes a high gas
barrier layer, the body having a side wall extendin~ frmi-ts top where i-t
has an annular sealing surface to i-ts bottom where it joins with
an integral bottom wall, the side wa:ll being adapted to resist
paneling in response to internal vacuum in the container, and -the
30 bottom wall being adapted -to flex inwardly in response to an inter-
nal vacuum to prevent the side wall from paneling, providing a
flexible high gas barrier closure disc -to close said container,
- 4b -
filling the container w:i.th a foodstuff to a level which leaves an
unfilled volume in the container, under condi-tions sufficient -to
develop high moisture vapor pressure in the con-tainer, promp-tly
herme-tically sealing -the open top by bonding -the closure disc to
the sealing surface in a substantially fla-t plane across the sur-
face, said disc being adapted -to flex from said plane to a more
inward position in response to an internal vacuum to prevent the
side wall from paneling, said inward flexings of the bot-tom wall
and closure disc being cooperative -to prevent development of high
internal vacuurn upon cooling of -the food product, and cooperative
with the paneling resis-tan-t side wall, -thereby -to prevent inward
paneling of the side wall, said sealing of the closure disc being
effected by using an adhesive selected to provide a seal which is
hermetic, will wi-thstand the potentially high internal vacuum
developed in the con-tainer and the inward flexing of the closure
disc, wi-ths-tand the reduce par-tial internal vacuum which exists
subsequent to the flexings, and yet provide easy peel-opening of
the closure disc.from -the con-tainer. Suitably-the method includes the ~-tep
of providing a bulk layer as one of said layers with said bulk layer
20 formed at least in part from reground scrap from materials of said
other layers~ Desirably-the me-thod includes-the step of bonding the closure disc
.to-the sealing surface with a T-peel streng-th of from about 3 -to 5
pounds per inch. Preferably-the method includes the step of providing an ethylene
vinyl alcohol copolymer as a barrier layer.
The present invention will be further illus-trated by way
of the accompanying drawi.ngs, in which:-
Figure 1 is a side elevational view of a pair of con-
tainer bodies emboclying the principles of -the instan-t invention,
the bodies being shown in nested posi-tion with the outer body
30 sectioned to ill.ustrate certain details of construction;
Figure 2 is a top view of Figure l;
Figure 3 is an enlarged vertical cross-sectional view
, ; ~ .,
. - 4c -
3t~
-taken through the curled l1p formed around the periphery of a
Eilled container body, the view also showing por-tions of -the peel-
able closure disc and a heated sealing plate adap-ted to heat-seal
the disc onto the curled lip;
Figure 4 is an enlarged ver-tical cross-sectiona] view
taken -through the multiple layer wall of the container body;
Figure 5 is an enlarged vertical cross-sectional view
taken through a bottom corner por-tion of the container body; and
Figure 6 is a schematic cross-sectional view of -the
filled and sealed container after the -top closure disc and the
bottom wall of the sealed container have flexed inwardly as the
resul-t of the in-ternal vacuum created by the cooling of the hot
filled produc-t.
Referring to the drawings and in particular -to Figure 1,
there is shown a plurality of one piece thermoformed con-tainer
bodies 10 embodying the principles of the instant inven-tion and
disposed in stacked and nes-ted relationship. Each container body
10 has a cup shape and is formed with a tapered main or side wall
12 which at its bo-ttom end merges in-to a pedestal base, generally
indicated by the numeral 14, which forms the bottom end portion
of the container. The base 14 includes a rounded corner portion
15 which connects the base 14 and the side wall 12, and an in-
wardly and downwardly angled reinforcing wall 16 which is disposed
at abou-t a 45 angle. The angled wall 16 merges in-to a shor-t ver-
-tical wall 18 which in turn connects with a horizon-tal or trans-
verse bottom wall 20 which is formed with a plurality of annu:Lar
grooves or corrugatic)ns 22 which cross-sectional configura-tion de-
fines means which permit diaphragma-tic flexing of the wall 20, as
will be hereinafter explained. As best seen in Fig.s 5 and 6,
the bottom wall 20 be-tween the outermos-t annular groove 22 thereof
and the pedestal base wall 14 includes a downwardly extending
annular bead which provides a seating surface for the container.
,~ - 4d -
A plurality of spaced, vertical, inwardly extending indentat:Lons
24 which at their upper ends create inwardly ex-tending ledge por-
tions 25 which faciIi-tate non-wedging nes-ting of -the container
bodies 10 and which also strengthen the bottom por-tion of -the con-
tainer body and help -to reinforce it against deformation, are
formed in the pedestal base 14.
As best shown in Figure 3, the -top of container body 10
is formed with a peripheral curled lip 26 having a top portion
28. The -top portion 28 provides an annular sealing surface which
10 is impor-tant from the standpoint of ensuring proper sealing of the
container as will become more apparent hereinafter. A flat annular
lip, rim or flange or combination thereof wi-th a curled portion
may also be used.
The materials used in -the construction of container body
10 comprise multiple layers including an inner polyolefin layer 32
made preferably of polyethylene or polypropylene or blends thereof,
an adhesive layer 34 made preferably of a compa-tible material
such as a modified polypropylene or a modified polyethylene, a
barrier layer 36 made of a plastic material such as ethylene vinyl
20 alcohol copolymer, saran, e-tc. which is substantially impervious
-to oxygen, another compatible adhesive layer 38 similar or iden-ti-
cal to the layer 34, a bulk layer 40 preferably bu-t no-t neces-
sarily consisting of reground scrap genera-ted during manufacture
of -the bodies 10, and an outer polyolefin layer 42 preferably
similar or identical in composition -to the inner polyolefin layer
32. It will be appreciated that the barrier layer 36 serves pri-
marily to prevent oxygen from pene-trating the container af-ter fil-
ling and sealing, although i-t may also serve as a barrier for other
gases or fluids. The layer 40 functions primarily to add bulk and
30 strength to the
- 4e -
body at low cost. The thicknesses of the various body layers can be
varied as desired and required, but it has been found that cup
shaped bodies constructed from these mult;ple layers should have a
total thickness of at least 15 mils and preferably of about 20 mils.
In accordance with the invention the container body 10 is filled
with a hot liquid product such as jam 50 which has been heated to a
temperature up to about 190F. AFter filling, the container is
sealed with a flat imperforate and impervious closure disc 5S which
is preferably made of aluminum foil 56 provided on its undersurface
a heat sealable adhesive layer 57 capable of adhering to top portion
28 of the curled lip 26 of the body 10. If desired, a suitable
oxygen-impervious thermoplastic material such as ethylene vinyl
alcohol copolymer (EVOH) or saran may be substituted for the
aluminum foil 56.
The closure disc 55 may be a laminate in which the aluminum foil
56 is laminated on one or both sides to a suitable layer of a
protective plastic material such as a nylon, a polyester or a
polyoleFin, one of which may function as the adhesive 57 which
adheres the disc 55 to the annular body portion 28. Preferably, the
hot melt adhesive 57 is chosen to provide a peel strength
sufficiently low in magnitude to permit easy peeling of the disc 55
from the body 10 when it is desired to open the container. It has
been found that T-peel strengths (ASTM D 1876-72) on the order of
about three pounds per inch are ideal for the present purpose, since
they permit easy opening of the container while at the same time
providing sufficient strength to maintain the integrity of the seal
during normal processing and handling of the container, as will be
more fully described. Substantially hiyher T-peel strengths than
the ideal peel strength such as greater than five pounds per inch
will provide thle resistance necessary to maintain the seal
integrity, but they prevent easy peelability of the closure disc.
f~
The cover di.sc 55 is preferably formed wi.th a small,
integral, radially projec-ting opening -tab 58 and may be applied
in any suitable manner as by a flat heated sealing ring or plate
59 which engages -the upper layer 60 of the closure disc 55 and
presses its peripheral edge por-tion against the -top surface 28,
while at the same time heating the disc 55 sufficiently to sof-ten
the adhesive 57 and cause it to heat-seal -to the top annul.ar sur-
face 28. The contacting surface of -the sealing plate 59 may be
coated with Teflon or the li.ke -to prevent the upper surface of the
10 closure disc 55 from sticking to it.
It will be appreciated that upon subsequent cooling of
the hot filled product 50, the closure disc 55 and bot-tom wall 20
are pressed inwardly by atmospheric pressure as a subsantial par-
tial vacuum, is formed wi-thin the sealed con-tainer due primarily
to condensation of moisture vapor which is present in the head
space 62 of -the filled and sealed container. For a completely
rigid container, the vacuum formed upon cooling would be about 20
inches of mercury. The purpose of this container is for use with
liquids -that have a measurable vapor pressure when hot-filled such
20 that upon cooling, a vacuum is generated. For commercial filling
operations, head space 62 is desireable to prevent over-filling of
the containers and spilling the contents jus-t prior to the heat
sealing operation. It will be fur-ther appreciated -that because of
this inward flexing of the closure disc 55 and bo-ttom wall 20, the
partial vacuum is substantially reduced and the s-tresses on the
closure seal and the side wall relieved so that the container seal
is maintained and deformation or paneling of the side wall 12 of
the container is prevented, as seen illustratively in Fig. 6 and
wherein the side wall is free of deformation or paneling -through-
:30 out its periphery. Annular grooves 22 provide -the means for the
flexing motion of bo-ttom wall 20. Because -the diameter of the
pedes-tal wa]l 14 as defined is -the minimum diameter of the con-
-- 6
..'~
38~
tainer slde, the stifEness ~t the junction between the pedestal
wall 14 and slde wall 12 is stiffened. 'rha-t s-tiffness is essen-
tial -to permi-t the -Elexure at the annular grooves 22 and -to prevent
deforma-tion at
- 6a -
,- :
38~
the juncture o~` the pedestal and side wall 12. It should be
understood that the high internal vacuum formed within the sealed
container also subjects the pedestal base 14 to a high pressure
differential, and unless some provision is made to prevent it, could
cause it to partially deform inwardly before or at the same time as
the bottom wall 20 i.s being flexed inwardly. This undes;rable
result is prevented by the reinforcing wall 16 which supports the
pedestal base 14 at the area of its greatest vulnerability, and thus
limits the inward movement of the body 10 to the inward flexing of
the bottom wall 20.
After cooling, and in the proper case solidification of the
product 50, the container may be easily opened by having the user
grasp the opening tab 59 and pull upwardly on it, thus breaking the
adhesive bond and peeling the closure disc 55 from the top sealing
surface 28.
