Note: Descriptions are shown in the official language in which they were submitted.
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Case V-5223
IN~USION PACKAGh
The pre~ent invention is directed to infusion packages,
especially tea packages and the like, and more particularly to
an infusion packag~ constructed of a non-woven, fiber-free,
perfora~ed thermoplast~c film or other porous material.
The invention is particularly concerned with an lnfusion
package constructed of a coextruded multilayer perforated thermo-
plastic film having a plurality of uniform minute holes or
openings therein, which has a relatively flat configuration for
0 packing and which can be readily converted to a dual chamber or
flow-through type bag.
At the present time, most tea bags or packages commer-
cially marketed are either the ~pillow~ pack type or the dual
bag or Flo-thru type. The bags are made of paper and the latter
have strings and tabs attached thereto by staples or glue. Al-
though a considerable degree of success has been achieved with
these two types of bags, they have poor wet strength. The single
compartment or Cpillowr tea bag is a flat bag of liquid pervious
material which contains sufficient tea for an individual serving
or for multiple servings in the case of the larger packages used
by food service industries. The tea spreads the sides of the
bag to accommodate the contents. When the tea is wet, it forms
a swollen compacted mass that may fill the bag. The swelling
tea presses outwardly against the inside walls of the bag.
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Squeezing or other ex~ernal pressure on the bag may cause it to
break open or split or otherwise undesirably dispel its contents.
To overcome thl~ swelling, ~ome bags have been constructed with
pleat~ therein~ Although effective to some degree, they have a
lack of wet strength and present other problems.
The art is replete with lnfusion packages containing
two or more fill containing segments. The connected segments
permit liquld flow between the segments and expose a greater bag
surface area to liquid ior extraction therethrough. Although
such bags may improve brewing, they have the same lack of wet
strength of the pillow~ type bags, and present other problems,
such as assembly and packaging.
Infusion-type tea packages are usually rectangular
packets or sachets made from single or mult$ple pieces of paper
crimped or otherwise sealed along the edges. In another type, a
single strip of paper is folded twice longitudinally to form an
inner centrally disposed double fold joining the two meeting
edges. In a type of flow-through tea bag, a triple transverse
fold intermediate the length of the folded strip forms two
pockets which are partially filled with tea before the open ends
thereof are folded over and stapled to a strand of string usually
having a tag on the end thereof.
Over the years, a wide variety o infusion packages or
bags, usually for containing tea for subsequent brewing, have
been developed. The packages are usually constructed of filter
paper or some other type of porous material.
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An infusion package which has a natural, expanded or
unflattened condition and which is folded to a flattened confi-
guration for packlng is disclosed in U.S. 4,290,521. A pull
strip with a tab on one end is adhesively attached to the upper
part of the package for causing the package to be expanded from
its flattened configuration when the strip is pulled.
A type of dosage pack or infusion package having two
permeable bags joined to each other along a common seam and
arranged in a face-to-face relationship by folding the bags onto
0 one another along a fold line extending in the common seam is
described in U.S. 4,055,668. A holder string is positioned
between the two bags with one end attached to one of the bags
and the other end attached to a tag positioned externally of the
two bags.
U.S. 3,899,599 discloses a single chamber or dual chamr
ber tea package which has a flexible strip attached to an exte-
rior chamber side which can be partially removed to provide a
hanger for holdlng the package in place in a container.
An infusion packet having two oppositely disposed,
rigidly separated pockets of tea joined together by two tapering
end port$ons which form a nar!ow, triangular shaped porous cup
is shown in U.SO 3,597,222.
U.S. 3,653,913 discloses an infusion bag made from a
rectangular strip of porous fibrous material, the longitudinal
margins of which are folded together so as to form a longitudinal
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~oint consisting of three layers which are knurled together.
The tube i8 divided by a transverse bend so a~ to form a pair of
chambers for holding an infusible substance, and the opposite
ends of the tube are connected to each other so as to close the
package.
An early type of tea bag or tea ball wheeein the bag is
a triangularly-shaped pocket formed from a rectangular strip of
perforated aluminum foil is described in U.S. 1,581,578.
Other types of filter paper tea bags or the like with a
10 variety of handles are illustrated in U.S. 2,328,017 U.S.
2,359,292, U.S. 3,566,573; U.S. 4,153,153 and Great Britain
2,087,350. Great Britain 2,053,668 discloses a tea bag having
an accordion fold.
Infusion bags with positioning means and flotation means
15 are di~closed in U.S. 3,797,642 and U.S. 3,809,215, respectively.
The tea bags themselves may be made of various materials inclu-
ding paper, plastics such as nylon, perforated plastic film,
e.g., polyester, or woven or non-woven fabric of natural or
synthetic origin.
A percolatable porous bag constructed of a blend of
individualized textile or cellulosic fiber and a small amount of
thermoplastic fiber is disclosed in Canadian patent 802,720.
Various degrees of success have been achieved with the
foregoing infusion bags or packages, with paper or fibrous bags
presently dominating the market place. One of the problems with
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paper bags is iack of wet str~ngth. Paper packages do not have
the strength to withstand squeezlng or other pressures commonly
applied by consumer or other u~ers.
kn ~rfusion bag for items such as tea, coffee or similar
food products for brewing must have a number of qualities. It
must have an inab$1ity to impart a taste factor to the liquid
product after brewing. In effect, it must be substantially odor-
less and tasteless. It must also be sufficiently strong to con-
tain the brewing product in boiling water, e.g., in the steeping
0 of tea, coffee, and similar liquid beverages. The bag must also
be porous enough to permit liquid diffusion therethrough, but
the pores or openings must be of such size that migration of the
beverage material therethrough is inhibited, both when the bag
is dry and when the bag has been immersed in a liquid. It is
also imyortant that infusion begins to take place within a few
seconds and be completed within a few minutes. It is further
desirable that a package, bag or sachet, such as a tea sachet,
retain sufficient stability that it can be compressed after
brewing is completed without destruction of the container.
Thermoplastic films such as polyethylene and polypro-
pylene are common packaging materials. Multilayer films of
various types are also quite common packaging materials. The
films are generally non-porous and impervious to water and other
inert liquids. At least one of the layers of film has strong
adhesive qualities. Examples of such multilayer films may be
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seen in U.S. 4,254,169- U.S. 4,239,826; U.S. 4,233,367,
U.S. 3,908,070; U.S. 3,423,231; U.S. 2,817,124 and
U.S. 2,817,123.
Perforated thermoplastic films have many useful
applications, including packaging of food products such as
cheese, gardening and farming to prevent growth of weeds
while permitting moisture to be transmitted through the film
to the soil beneath and for making absorptive structures such
as disposable diapers,for example, see U.S. 3,814,101.
Perforation of thermoplastic films is generally
achieved by vacuum perforation of thin plastic films which
involves the extrusion of molten polymeric materials such
as polyethylene through a slot die. The hot melt web of
film exiting the die impinges on a form through which a
vacuum is drawn causing the film web to be perforated and
holes formed therein. Depending upon the form used, films
can be produced which have as few as 50 holes per square
inch or which have thousands of holes per square inch. One
of the earlier methods for vacuum perforation of plastic
film is disclosed in U.S. 3,054,148.
The present invention provides an infusion package
or sachet which meets the requirements for tea brewing and
additionally overcomes the problems of lack of wet strength
and packaging associated with the prior art.
More particularly, the present invention provides
an infusion package for particulated or finely ground products
consisting of a tube of porous material having a central
product containing portion and an elongated flattened end
portion on each end thereof, the ends being oppositely
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located ends, each of the flattened end portions being
sealedly separated from the central product containing
portion, the flattened end portions being sufficiently
elongated that they may beinterwoven or knotted together,
whereby when so interwoven or knotted together a flow
through type of package with an intearated handle thereon
is formed,allowing a majority of the central product con-
tai~ina portion to be suspended therebelow, at least one of
the flattened end portions having an elongated slot or
opening therein which enables one flattened end portion to
be inserted through the other flattened end portion and
thereby form the flow through type of bag with an integrated
handle thereon, and ^the porous material having a multiplicity
of fine openings or holes therein each of which is sufficientlv
small in si7.e to inhibit migration therethrough of a part-
iculated product contained in the central product containing
portion and is sufficiently large in size to permit the flow
of liquids therethrough.
Fig. 1 is a top plan view of an embodiment of the
invention;
Fig. 2 is a side elevational view of the embodiment of
Fig. l;
Fig. 3 is an end view of the embodiment of Fig. l;
Fig. 4 is a sectional view taken across line 4-4 of
Fig. l;
Fig. 5 is a top view taken across line 5-5 of Fig. l;
Fig. 6 is a view of the e~bodiment of Fig. 1
illustrating one means of joining together the ends of the
package; and
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Fig. 7 is a view similar to that of Fig. 6 illustrating
another means of joining the ends of the tea bag.
Referring now to the drawings, an infusion package or
bag of the present invention is illustrated generally at 10.
The bag or packet 10 is constructed of a rectangular strip of a
perforated plastic film 11 which is described in more detail~
hereinafter. For simplicity of illustration, perforations in
the film are not shown. The strip of film 11 is folded longitud-
inally at 12, sealed at intermediate locations 13 and 14 and
filled with a particulated product P which can be seen through
the film 11 between the sealings. After the product P is
inserted in the sachet 10, the edge 15 is sealed, thereby
encasing the product P within the package 10.
The intermediate sealings 13 and 14 provide tabs 16 and
17 on either side of the product P. Conveniently, slits or
longitudinal slots 18 and 19 are formed in each of the tabs 16
and~17-, respectively.
As best seen in Figs. 1 and 2, the ends of the elongated
flattened end portions (or tabs 16 and 17) are located oppositely
of the central produc~ containing portion or the portion between
the sealings 13 and 14 containing the product P. The flattened
end portions are sufficiently elongated that they may be inter-
woven or knotted together as shown in Figs. 6 and 7, respectively.
Once the package 10 is interwoven or knotted together, a flow
through package 10 is formed with an integrated handle thereon.
In flow through form, a majority of the central product contain-
ing portion is suspended below the handle formed by the flattened
end portions.
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The infusion package 10 of the present invention is
illustrated in its simplest form. Such packages can be
readily made on existing filling and packaging machines with
minimal modification. The relatively flat shape of the bags
permits easy packaging or boxing in a fashion similar to that
of boxing cigars.
- Figs. 6 and 7 illustrate two means by which the package
10 is readily converted to a flow through or dual container in-
fusion bag. In Fig. 6, tab 16 is inserted through slot 19 of
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tab 17. Tabs 1~ and 17 are of sufficlen~t length to provide a
handle which can readily be extended over the side of a cup or
brewing pot.
Ir, ~ig. 7, the slots are not used and the tabs are
assembled in a half knot or full knot, if desired. The tabs 16
and 17 are sufficiently long to easily provide the desired
handles.
The infusion bag or package 10 is preferably constructed
of a coextruded multilayer film 11 comprising an outer layer of
1~ a heat resistant thermoplastic such as polyester, polyolefin, or
the like, with p~lyester being preferred, and an inner sealant
layer of a somewhat less heat resistant thermoplastic such as
polyethylene or the like. The film 11 has a multiplicity of
fine holes or capillaries which are of a somewhat tapered con-
struction, being more or less in the form of a truncated conewhen the holes are round or oval.
For simplicity of illustration, the holes or openings
in the film are not shown. It can be appreciated that the
openings may be of any desired shape such as round, oval,
rectangular, pentagonal, hexagonal or other geometric
configuration. It is desired that the holes be uniform and that
they be sufficiently large in size and number to provide
adequate infusion and be sufficiently small in size to prevent
the migration of particles therethrough such as the particulated
product P.
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In the packaging of an item such as tea, a preferred
hole size is fro~ two to 10 mils (0.00508-0.025~ cm), in
diameter or across the opening, with a size of three to four
mils ~0.00762-0.01016 cm) being most preferred. The film has a
thickness of 0.25 mil to two mils (0.000635-0.00508 cm) and 500
holes per square inch (77.5 holes per square centimeter) or
more. From 1800 to 4200 holes per ~quare inch (279 to 651 holes
per square centimeter) are preferred, with about 2900 holes per
square inch t449.5 holes per square centimeter) being most
preferred. The porosity of the film is preferably 50 to 500
cubic feet per minute (CFM)~23,597 to 235,973.7 cubic centimeters
per second).
The outer layer of the coaxial or coextruded perforated
thermoplastic film of the bag is preferably a heat resistant
polyester film having a melting temperature of 425F to 600F
(218.83C to 315.56C) with about 525F (273.89C) being most
preferred. The inner sealant layer of the coextruded perforated
thermoplastic film of the bag is preferably a somewhat less heat
resistant polyethylene film having a melting temperature of
180F to 250F (82.22C to 121.11C) with 220F ~104.44~C) being
most preferred. The use of an outer polyester layer enables a
sealing/melting temperature differential of about 150F (65.56C)
to be obtained. The film has a desired seal strength of 3/4 lb.
per inch (133.9 grams/centimeter) width.
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A temperature of about 240F ~115.56C) is required to
melt the polyethylene film for sealing. To prevent sticking of
the outer layer of thermoplastic film to the steel jaws of the
sealing device or heat sealing machine, it is impcrtant that the
melting temperature of the polyethylene be kept below about
260P (126.67C). It can be appreciated that particular
polyolefin resins or other fLlm forming resins may have h~gher
or lower melting temperatures; however, it is essential that a
melting temperature differential be obtained between each layer
0 to achieve the desired ~eal without a deleterious effect on the
film.
The edges of the bags and the intermediate sealing areas
may be readily heat sealed using standard sealing and automatic
bag making machines. The edges and intermediate sealiny areas
may also be effectively sealed with use of impulse or band type
sealers, hot wires, hot air or other suitable apparatuses or
techniques.
The longitudLnal edge of the film is heat sealed to
complete the package. The melt flow of the outer layer must be
sufficiently high to prevent the film from sticking to the
sealant jaws. The melting temperature of the inner sealant layer
must be less than the melting temperature of the outer layer,
but sufficiently high to melt the inner layer and achieve the
desired seal.
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For the packaging of a typical commerc~al tea for
brewing, a perforated thermoplastic film suitable for construc-
ting the infusion bag is a coextruded polypropylene/polyethylene
perforated thermoplastic film formed from a high density poly-
ethylene resin and a polypropylene resin. The resins are odor-
less and tasteless and approved for food packaging.
The film is preferably clear in color, but may be manu-
factured in its natural color or a variety of colors as desired
or permitted by governmental regulations, etc.
The film has a dry surface and has no tendency to stick,
cling or ~block~.
Perforated thermoplastic films suitable for use in the
invention have a male side and a female side. In construction
of infusion bags, the male side of the film is on the inside of
the bag. This relationship effectively seals the tabs of the
package which are positioned on either side of the product con-
taining pocket or area.
The invention is illustrated in its simplest form, and
as a typical small size infusion bag for the packaging of indivi-
dual servings of tea for brewing. Larger size packages, such asthose customarily used in the food services industry, can also be
constructed. Such larger bags can be similarly constructed or
constructed of two rectangular strips of film and sealed on all
four edges. The bags or packages of the invention can be con-
structed in other geometrical configurations as desired, but
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rectangular shaped packages are generally more suitable for
boxing or other type of group pa~kag$ng and can usually be more
easily fabricated.
The product i8 confined to the center portion of the
tube and the ends are heat sealed to form the tabs. Other
sealing methods can be used if desired, but heat Bealing i6 pre-
ferred. The flat tabs also provide a good surface for logos,
advertising, lnstructions or for other printing.
Although the cross-sectional geometry of a filled bag is
0 somewhat circular or oval, it can be of any desired geometrical
configuration, for example, a star shape to promote flow and
greater surface exposure. In another form of the invention, two
narrow strips or ribbons of thermoplastic film are aligned male
side to ~ale side. The product, such as tea, is deposited in a
thin layer on the top (male) surface of the bottom ribbon. The
top ribbon is then laid over the product, sealed along each edge
and intermittently spot sealed between the edges in a regular
pattern or an irregular pattern. The spot seals hold the two
ribbons together in close proximity and prevent the product from
bunching~ The male surfaces of the film are effectively utilized
to prevent the tea or other product from bunching thereby keeping
maximum tea surface exposed for brewing.
In addition to the advantages set forth hereinbefore,
the present invention also provides improved product distribu-
tion, of~ers the possibility of rapid filling, eliminatesstrings, staples or other extraneous mat.er. A unique means of
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squeezing a bag is provided by simultaneously pulllng collapsed
ends of the tube or package.
Although a coextruded multilayer perforated plastic
film i8 preferred, other types of perforated thermoplastic films
may be used. Such films, of course, must provide adequate
infusion and sufficient strength for the purposes intended.
Some examples of film forming resins suitable for making
the perforated thermoplastic films of which the infusion packages
of this invention are constructed are polyethylene (PE), poly-
0 propylene (PP), crystalline polyester (CPE), amorphous polyester(APE), polycarbonate (PC) and nylon (N).
Some examples of multilayer films suitable for use in
constructing the infusion pa~kages of the invention are, in
addition to CPE/PE, as follows:
PP~PE PC/PE N/PP
CPE/PP PC/PP N/PE
CPE/APE PC/APE N/APE
In addition to dual layer thermoplastic films, triple
layer films or films having as many layers as desired can be
used. Such films, of course, must be of the perforated type and
meet desired infusion rates and packaging requirements.
Although the ~nvention is particularly directed to
infusion packages or bags constructed of perforated thermoplastic
films, it is suitable for use with other types of porous
materials including paper, cloth or other similar type materials.
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These porous materials must also provide adequate infusion and
8 ufficient strength for the purposes intended.
Although the invention i particularly suitable for the
packaging of tea, it can be use~ for packaging of other types of
finely ground or particulated food products such as coffee and
grits. The bags may be used for packaging of any items in which
infusion of liquids is desired.
The infusion bags of the present invention have excel-
lent wet strength and will not deteriorate in boiling water.
The bags themselves are odorless and tasteless and do not impart
any foreign taste to the item being packaged. They are, in
effect, substantially inert.
