U.S. patent number 3,748,816 [Application Number 05/109,560] was granted by the patent office on 1973-07-31 for method of sealing a container.
Invention is credited to Richard W. Asmus.
United States Patent |
3,748,816 |
Asmus |
July 31, 1973 |
METHOD OF SEALING A CONTAINER
Abstract
A reclosable container having a removable top closure
mechanically joined to the container body to carry the structural
loads of container and contents, the mechanical joint being
cylindrical and connected and disconnected by rotation of the top
closure and the container body relative to each other. The ultimate
seal during the shelf-life between filling and initial opening of
the container is effected by a rupturable band adhered over the
joint, said band in the locus of the joint line having a strength
in shear less than its adhesive bond to the container closure and
body adjacent the joint line. The closure and body are preferably
recessed adjacent the joint line to receive the band. The band is
preferably endless and formed in situ by application of band
material in liquid condition; a repellent or adhesion inhibiter
(preferably an immiscible liquid) may be located in or over the
joint line to exclude entrance of the band material into the joint
and provide an equatorial area of weakness for rupture of the
sealing band.
Inventors: |
Asmus; Richard W. (Cleveland,
OH) |
Family
ID: |
26807085 |
Appl.
No.: |
05/109,560 |
Filed: |
January 25, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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863105 |
Oct 2, 1969 |
3608772 |
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Current U.S.
Class: |
53/420 |
Current CPC
Class: |
B65D
39/10 (20130101); B65D 45/00 (20130101) |
Current International
Class: |
B65D
39/10 (20060101); B65D 45/00 (20060101); B65D
39/00 (20060101); B65b 061/00 () |
Field of
Search: |
;53/15,18,39,139.3
;156/69 ;215/40,47,95 ;220/45,53,55AN,80 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Spruill; Robert L.
Parent Case Text
This application is a divisional application with respect to my
copending application Ser. No. 863,105, filed Oct. 2, 1969, now
U.S. Pat. No. 3,608,772.
Claims
What is claimed is:
1. A method of sealing a container comprised of a body having a
mouth portion with a substantially circular edge and closed by a
closure interfitting said mouth portion to provide a circular outer
joint line comprising the steps of locating a sealing band over
said joint line and circumferential areas of said closure and said
mouth portion adjacent said joint line and adhering said band to
said marginal circumferential areas with adhesive bonds stronger
than the shear strength of said band while avoiding such adhesion
of a medial portion of said band at said joint line.
2. A method as defined in claim 1 including the step of filling
said joint line with a repellant to adhesion to said sealing band
prior to locating said sealing band over said joint line.
3. A method as defined in claim 2 including the step of forming
said sealing band in situ by applying a polymeric resinous liquid
coating over said joint and adjacent marginal circumferential areas
and curing said coating to a solid condition to adhere the same to
said circumferential areas but without adhesion at said joint
line.
4. A method as defined in claim 3 including the step of reinforcing
said sealing band with an overlying band of flexible but relatively
inelastic sheet material of the class consisting of metal foil,
organic film, paper, and laminates thereof.
5. A method as defined in claim 1 in which said sealing band is
comprised of a strip of flexible sheet material of the class
consisting of metal foil, organic film, paper, and laminates
thereof and including the step of joining the ends of said strip
with a transverse overlapped seam to form and locate said band.
6. A method as defined in claim 5 including the step of first
folding marginal portions of said strip toward the longitudinal
center thereof and joining the same to the unfolded portion of said
strip to provide a strip having marginal portions of greater shear
strength than the medial portion thereof.
Description
This invention relates to an improvement in containers and a method
of making them. More particularly this invention relates to
containers having a removable top closure which is, on the one
hand, readily opened manually without the aid of opening tools or
equipment, and, on the other, provides a mechanically strong and
thoroughly sealed closure whereby solid and liquid material may be
packaged and maintained at suitable pressures (either
sub-atmospheric or super-atmospheric if not simply atmospheric
pressures) during the expected shelf-life of the packaged contents
between the filling of the container and its initial opening by the
user.
Both as an element of commercially produced closures for cans,
jars, or like containers, or as a temporary means employed by users
for securing the covers or lids on such containers, it has long
been a common practice to employ an external adhesively secured
band wrapped around the substantially cylindrical wall formed at
the joint or line of juncture between the closure member and the
body of the container. Thus, in a can closure, for example, in
which there is simply a frictional slip joint between the
cylindrical wall of the container body and a depending flange of a
top closure, it has been commercial practice to over-wrap the joint
with a removable band of an adhesive tape or the like, both to
secure the closure member from accidental removal and improve its
seal. Likewise, it is a common expedient for housewives, for
example, to secure the screw top of a can or jar, after opening and
reclosing, with a strip of pressure-sensitive tape which is removed
to allow ready re-opening of the container. In the quest for
readily-opened containers, particularly those by which liquid
and/or solid materials can be packaged under super-atmospheric
pressures or vacuum or those in which the processing of the
contents after filling and closing may develop substantial internal
pressure, the foregoing expedients of using an external band to
effect sealing have not been successful, despite their
convenience.
It is an object and advantage of this invention to provide a
sealed, reclosable closure for cans, jars, and the like which may
be readily opened, the sealing being effected by an externally
applied sealing band. It is an advantage of this invention that,
during the expected shelf-life of the packaged contents, and
irrespective of whether the contents are packaged at atmospheric
pressures, super-atmospheric pressure, or under partial vacuum, the
packaged contents will be thoroughly sealed but, nonetheless, may
be manually opened without requiring the aid of opening tools or
accessories. Further, such opening and rupturing of the seal may be
accomplished substantially instinctively by the user and without
the need for unusual operations or instructions therefor which may
be overlooked or not followed by the users.
Other objects and advantages of this invention will be apparent
from the following specification, claims, and drawings, of a
preferred embodiment which may be substantially modified in whole
or part:
FIG. 1 is an essentially diagrammatic representation in
cross-section of the upper portion of a metal can having a
bayonnet-type of joint for a closure top which may removably close
and reclose the can, the can being effectively sealed after filling
and until it is initially opened by the user.
FIG. 2 is an elevation of the preferred embodiment disclosed in
FIG. 1.
FIG. 3 is a cross-section of an alternate form of sealing band
which, when applied to a container as illustrated in FIG. 1, may
have the external appearance shown in FIG. 2.
It is to be understood that in the accompanying drawings the
thicknesses and proportions of the several elements shown have been
exaggerated for clarity of illustration, and, for the smame
purposes, structural details, such as the beading of raw edges of
sheet-metal used for cans or lids, for example, have been
eliminated.
In essence this invention depends upon separating the functions of
the conventional gasketed screw or bayonnet locked top or lids for
cans, bottles, jars, and the like of both providing the structural
strength of the closure to resist mechanical loads on the closure
and also sealing the joint between the closure and the container
body by compressing a gasketing member located in the joint.
Particularly if the contents are packaged so as to maintain a
pressure differential from that of the ambient atmosphere or if,
after the contents have been packaged, the package must be
subjected to processing which generates substantial pressure within
the closed container, the mechanical tightening of the screw or
bayonnet connection necessary to compress the gasketing material
adequately imposes such a frictional load between the mating thread
or lug portions of the connection that it becomes extremely
difficult to loosen the connection for opening without the aid of
an opening device or resorting to such expedients as tapping the
closure to dislodge the connection or heating the closure so as to
expand it without expanding the mating portion of the connection.
By reducing the function of the gasketing member, if one is
employed, to that of simply filling gross gaps or discontinuities
in the joint between the container closure and body and relying
upon an external sealing band covering the joint, adequate
structural strength to resist any normal mechanical load on the
container may be obtained without frictional resistance to easy
opening.
The problems heretofore inherent in transferring such sealing
functions to an external sealing band have been solved in this
invention by the discovery that various suitable banding materials,
inert to the packaged contents and the ambient atmosphere, may have
more than adequate strength to seal any leakage from the contents
through the mechanical joint of the closure and the container (or
leakage into such contents) and yet are so relatively weak in shear
strength that they will rupture in shear rather than break an
adjacent adhesive bond to structurally stronger materials, such as
the sheet metal, glass, or plastic conventionally used for
containers and container closures.
To illustrate the application of this discovery to the invention,
reference is made to FIGS. 1 and 2, as follows.
As shown in FIG. 1, a tubular can body 10, for example, is formed
of suitably plated and lacquered sheet metal and provided with a
closable opening or mouth portion 11 of reduced diameter. This
mouth portion 11 is formed with one or more, usually two or three,
internal grooves 12 (one is illustrated in dotted lines in FIG. 1)
extending downwardly from the rim of the mouth and then curving to
a gently pitched helical location below the rim to provide internal
bayonet joint slots or interrupted threads. The can body 10 is
closed with a drawn metal lid 20 having a downwardly depending
flange 21 forming a gripping portion substantially equal in
diameter to that of the can body. The flange is reduced in diameter
below the gripping portion to provide a gasket seat shoulder 22 and
below the shoulder 22, the flange 21 is further reduced in diameter
to a sleeve portion 23 which internally fits the can body mouth 11.
The sleeve portion 23 is formed with internal dimples 24 which form
raised bosses which are received in the grooves 12. Externally the
sleeve portion 23 carries a gasket ring 25 which is lightly
compressed between the shoulder 22 and rim of the mouth portion 12
when the lid 20, with the bosses of the dimples 24 received in the
grooves 12, is turned clockwise to draw the lid into the mouth
portion 11 of the can body 10.
Manifestly, the depending flange of the closure lid 20 may fit
externally of the mouth portion 11 of the can body 10, in which
event the gasket 25 will usually be located interiorly of the
flange so as to be engaged between an internal shoulder of the
closure lid and the rim of the mouth portion of the can body and a
second or alternate gasket may be located in the external
circumferential joint between the rim of the sleeve portion of the
closure flange 21 and the shoulder between the can body and its
mouth portion 11. The arrangement shown in section in FIG. 1 is
generally preferred, however, since it enables a relatively shallow
circumferential channel 26 to be formed between the lower edge of
the gripping portion of the flange 21 and the shoulder between the
can body and its mouth portion 11, locating the external joint line
between the can body and its closure in the center of the channel
26. If the sleeve portion 23 of the closure fits externally of the
mouth portion 11 of the can body, it is preferable to provide a
stepped shoulder between the can body and its mouth portion, the
upper step of such shoulder receiving either rim of the sleeve
portion 23 or a gasket engaged by that rim and the lower step
providing the lower side of a channel in which the external joint
line is centrally located. The radial depth of the channel 26 is
preferably such as to contain the outwardly extending ridges of the
grooves 12 below the cylindrical surface defined by the gripping
surface of the closure flange 21 and the wall of the can body 10;
this allows a cover tape 35, described below, to be flush with that
surface. Such a channel depth also usually allows any portion of
the gasket 25 which may be bulged when the closure 20 is tightened
and drawn into the can by operation of the bayonet lock effected by
the grooves 12 and dimples 24 to be contained within the
channel.
Manifestly, instead of the bayonet lock illustrated as the
mechanical connection between the can body 10 and closure 20, the
location of the dimple 24 on the sleeve portion 23 and the groove
12 on the mouth portion 11 may be reversed or a coarse screw
connection of one or more continuous or interrupted threads may be
employed. Likewise, while the container body 10 and closure 20 are
indicated as being of formed sheet metal in FIG. 1, manifestly the
same container structure and closure structure may be molded of
plastic, glass, ceramics, and/or other suitable material and the
material of the container body need not be the same as that of the
closure.
As indicated above, the gasket 25 is preferably only lightly
compressed as the container is closed by turning the closure 20
down on the container body 10; the function of the gasket 25, which
may be of natural or synthetic rubber or other elastomer,
polyethylene, an acrylic thermoplastic (e.g., "Barex 210"), molded
cork, compressible paper or film, and the like, is primarily to
fill any gross gap in the joint between the container closure and
body and to take up any play in the mechanical connection between
these two principal members of the container and secondarily to
provide a necessary mass to inhibit gas diffusion. With any sealing
function of the gasket 25 thereby being otherwise incidental, the
mechanical connection between the closure and body can thereby be
designed to be amply strong to withstand mechanical loads which the
container may be expected to encounter while holding the frictional
engagement between the locking elements to minimal loads that can
be pre-set within close tolerances.
The actual sealing of the contents of a container as described
above is effected by a sealing band 30, after the closure has been
connected as described above. The band 30 is preferably of a
polymeric film material which is relatively adherent to the
material of the can body 10 and closure 20 or which can be made
adherent thereto with appropriate adhesion promoter. It is
preferably applied by a roller coater, fountain brush, narrow knife
coater, or masked spray while it is in liquid form so as to cure or
be cured in the channel 26 at a sufficient depth to cover the
gasket 25 and thereby form itself in situ to an endless band.
Suitably plasticized vinyl plastisols, plasticized "hot-melt"
resins, and high solids content solvent dispersions or latices of
polymeric film-forming resins, such as epoxy-phenolic, epoxy-urea,
and polybutadiene resins, are examples of the general class of
materials which may be deposited in liquid form over the joint line
between the container closure and body to provide the desired
adherent sealing band.
When the adherent sealing band is formed in the channel 26 as
defined above, it is desirable to provide a non-adherent or less
adherent equatorial area in the locus of the joint line which will
permit ready rupture of the band in shear; this may be accomplished
by one of the following means: The materials of the gasket 25 and
the band 30 are either selected to be mutually repellent and
immiscible so that there is no significant adhesion between the
gasket 25 and band 30 or, prior to application of the band, the
exposed surface of the gasket is coated with a narrow strip of
liquid which blocks adhesion of the band to the gasket and which
also preferably seeps into any interface between the gasket and the
edges of the joint line; if no gasket is provided in the external
joint line, the joint is filled with such an adhesion blocking
liquid prior to application of the band 30. The composition of the
adhesion blocking liquid will necessarily vary according to the
composition of the band material and the relative repulsion or
immiscibility of them. For example, if the band 30 is formed of a
relatively hydrophobic vinyl plastisol, a relatively hydrophilic
glycerol or sugar syrup may be employed to block adhesion in the
locus of the joint. Alternatively, the sealant band-forming liquid
may be formulated so as to be sufficiently viscous or thixotropic
that it will not seep into the joint.
As an alternative to the formation of the sealing band 30 in situ,
one may employ heat-sealing tapes, such as a plasticized vinyl tape
which may be fused to itself and the container elements, provided,
of course, that an adhesion block is located in or at the joint
line of the container. If preformed films or tapes are used, care
must be taken to assure not only that a secure, leak-free vertical
seam between the butted or overlapped ends of the tape is obtained
but also that the tape is well adhered on either side of the joint
line while leaving an intermediate unadhered portion of sufficient
width over the joint line to allow shearing forces to develop and
rupture the tape as the closure and container body are twisted
relatively to each other to open the container.
Due to the reduction in thickness of the band 30 over the gasket
25, due either to the bulging of the gasket or the effect of the
adhesion blocking liquid, or both, there is thereby provided an
internal score line 31 for rupture of the sealing band 30 when the
band is subjected to shear by turning the closure 21
counter-clockwise to open the container. The thickness of the
sealing band at the locus of the joint may thereby be closely
controlled and effectively pre-set to limit the torque required to
open a sealed container. If the band 30 is formed from a length of
pre-formed tape or film, either an external or internal score line
may be cut into the tape to control the torque necessary to rupture
the tape and insure that the force necessary to do so will be less
than the adhesive bond to the container body and closure.
The sealing band 30 may be pigmented, if desired, to provide an
attractive ornamentation of the container. However, its surface may
be relatively soft and subject to scuffing during shipment and
handling. To so protect the band 30, and provide a printable
display surface and, in some cases, for sanitary reasons, a
protective band 35 may be employed. The band 35 may be an
encircling band of shrinkable cellulose, vinyl, or other shrinkable
film, or it may be a strip of paper, tough plastic, metal foil, or
a laminate of one or more of these materials; it may be adhered to
the sealing band 30 by a pressure-sensitive or like peelable
adhesive or may be simply frictionally secured by a tight seam of
adhesive 36 between overlapped ends, as shown in FIG. 2. In any
case, the band 35 is preferably provided with a free lift-tab 37 to
permit it to be stripped readily. The band 35 may also serve an
actual sealing function, particularly when made of metal foil or a
metal foil laminate, by increasing the impermeability of the
sealing band 30 as well as by serving as a reinforcement for the
polymeric resin of the band 30. For example, if the contents of the
container are packaged under a substantial vacuum or under
relatively high super-atmospheric pressures imposed by gaseous
contents, such a pressure differential could eventually rupture the
band 30 at one or more points along the line 31 unless the sealing
band were reinforced by the peelable or shrunk-fit band 35.
While it is preferred to form the sealing band 30 from a polymeric
resin in a liquid condition and which may be cured in place over
the joint line between the container body and closure, as described
above, this invention is not limited to use of such sealing band.
Particularly when a prime requisite for the sealing band is its
function as a barrier against transmission of moisture and like
vapors and gases, it may be desirable to form a band 130 of a metal
foil or laminated foil and/or paper or film. As shown in FIG. 3,
the band 130 may be formed of a strip having marginal portions 132
and 133 folded back on and preferably laminated to its center
portion 131 and either the marginal portions or the corresponding
areas of the center portion 131 are then adhered to the can body
and closure so that the line or space 134 between adjacent edges of
the marginal portion overlies the joint line between the closure
and body and is preferably free of adhesive in the locus of that
line. The ends of such a folded band of strip material may be
joined by a lapped vertical seam corresponding to the seam 36 shown
in FIG. 2 and the external end may have a lift tab corresponding to
the lift tabs 37 to rupture the vertical overlapped seam joining
the ends of the band. When adjacent adjacnet edges of the marginal
portions 132 and 133 are spaced to provide a gap 134 as shown in
FIG. 3 and the marginal portions are adhered to the can body and
closure, such a gap is usually sufficient to receive the bulging of
a gasket in the joint and may be made wide enough to insure that
any adhesive forced toward the joint line as the marginal portions
are pressed against the container and closure wall will flow into
the gap 134 rather than into the joint between the container body
and its closure and still leave an unadhered portion overlying the
joint line. When the material of the band 130 consists of aluminum
foil having gauge of 0.0001 to 0.0006 inch, it is usually desirable
to protect such relatively soft foil from abrasion by an overlying
removable protective band 35.
As in the case of a sealing band 30, a sealing band 131 can have
adequate structural strength to perform its function of sealing the
mechanical joint between the container body and its closure. Yet,
upon the manual application of torque (within limits which can be
pre-determined to close tolerances), the closure and container body
can be readily rotated with respect to each other so as to rupture
the band in shear over the joint line. A relatively clear line of
fracture appears to be aided by slight tension placed on the
circumferential line of weakness in the sealing band, which tension
is most conveniently obtained with a mechanical interlock between
the closure and container body which causes the closure to move
helically away from the container body as they are rotated with
respect to each other.
If this container body 10 is, as shown in the drawings, that of a
sheet metal can having a conventional crimped and sealed bottom
closure, the usual practice is to assemble and complete the closing
and sealing of the top closure according to the invention,
inverting the container to fill it with the contents introduced
through the open bottom, and then closing and sealing the container
with the conventional bottom closure. If the container body 10 is
that of a conventional jar or bottle which can be filled only
through an open mouth, this invention permits such filling with
most contents which can be packaged in such container. If, as in
the case of many foodstuffs, the contents to be packaged require
processing at high temperature after filling and sealing in order
to sterilize or pasturize them, an advantage of this invention is
that such processing temperature can also cure or complete the cure
of the sealing band so as to adhere it firmly to areas adjacent the
joint line of the closure.
While a sealing band rupturable in shear according to the invention
is preferably received in a circumferential channel in which the
joint line between the container body and closure is located, it is
to be understood that such surface configuration adjacent the line
may be omitted so that the band will protrude from the surfaces
adjacent the joint line. The rupturable sealing band is usually
cylindrical, or substantially so, since the joint line between the
container body and its closure is usually a circle lying in the
perimeter of an area provided by adjacent marginal portions of the
container body and closure, which area is essential cylindrical. If
the area defined by marginal portions adjacent the joint line is
other than essentially cylindrical, then, so long as it is
essentially the surface of a solid of revolution, a sealing band
130 can usually be shaped to lie over the joint line while being
adhered securely to the adjacent area of the container and closure;
an advantage of forming the band 30 in situ is, of course, that it
can accommodate itself to extremely irregular surfaces adjacent the
joint line.
Still other modifications and departures from the disclosed
specific embodiment of this invention can be made without departing
from the scope of the following claims. In the following claims, it
is to be understood that the term "unadhered" as applied to the
medial portion of the sealing band overlying the joint line as an
equatorial area between the adherent marginal portions includes the
modification of causing or allowing such circumferential area to be
more weakly adhered than, and thus relatively unadhered with
respect to, the more strongly adhered marginal portions. In this
connection, so far as it is understood, a function of such
unadhered (or less strongly adhered) circumferential medial area of
the sealing band appears to be that of allowing shearing strains,
adequate to rupture the band, to develop upon rotation of one
marginal portion of the band with respect to the other. It has also
been observed that, within the limits of a sealing band of a
material and thickness in its circumferential medial area capable
of being ruptured in that area due to torque applied to the
marginal portion which remains adhered, if resistance to rupture in
the medial circumferential area of the sealing band exceeds that
which is convenient for manual application of such torque, such
resistance may usually be decreased by increasing the axial width
of the circumferential area; similarly, if such resistance to
rupture is less than that desired, it may be increased by
decreasing the width of the medial unadhered portion.
* * * * *