U.S. patent application number 11/013646 was filed with the patent office on 2005-07-07 for lined container for curable liquid materials.
This patent application is currently assigned to Dow Global Technologies, Inc.. Invention is credited to Buschmann, Richard C. II, Cocca, Michael C., Fuchs, Hans J., Kneisel, Andrew R., Lux, Mark J., Mostoflzadeh, Janet S., Mouser, Dwain.
Application Number | 20050145632 11/013646 |
Document ID | / |
Family ID | 34710200 |
Filed Date | 2005-07-07 |
United States Patent
Application |
20050145632 |
Kind Code |
A1 |
Cocca, Michael C. ; et
al. |
July 7, 2005 |
Lined container for curable liquid materials
Abstract
A container for transporting and storing a curable composition
comprising a container and a liner of a surface treated plastic.
The liner is bonded to a cover about the periphery of the cover,
preferably with the material contained within the container.
Inventors: |
Cocca, Michael C.; (Shelby
Township, MI) ; Kneisel, Andrew R.; (Clarkston,
MI) ; Mostoflzadeh, Janet S.; (Beverly Hills, MI)
; Buschmann, Richard C. II; (Hillsdale, MI) ; Lux,
Mark J.; (Jonesville, MI) ; Mouser, Dwain;
(Hillsdale, MI) ; Fuchs, Hans J.; (Hausen am
Albis, CH) |
Correspondence
Address: |
DOBRUSIN & THENNISCH PC
29 W LAWRENCE ST
SUITE 210
PONTIAC
MI
48342
US
|
Assignee: |
Dow Global Technologies,
Inc.
|
Family ID: |
34710200 |
Appl. No.: |
11/013646 |
Filed: |
December 16, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60531051 |
Dec 19, 2003 |
|
|
|
Current U.S.
Class: |
220/495.01 ;
220/259.1; 220/359.1 |
Current CPC
Class: |
B65D 25/16 20130101;
B65D 81/268 20130101; B65D 51/20 20130101; B65D 81/245 20130101;
B65D 2251/0096 20130101; B65D 2251/0018 20130101 |
Class at
Publication: |
220/495.01 ;
220/359.1; 220/259.1 |
International
Class: |
B65D 021/02; B65D
041/00; B65D 025/14 |
Claims
What is claimed is:
1. A lined container comprising: a container for at least one
curable composition derived from phenolic and amino resins,
acrylics, polyurethanes or epoxies and comprising an interior wall
surface having at least one opening and defining an enclosed
cavity; a removable liner adjacent at least a portion of the
interior wall surface having a closure region consisting
essentially of a surface treated plastic film, which inner liner is
conformable generally with the shape of the cavity; and a top
closure comprising at least one plastic layer and an impermeable
layer; the top closure film having a size such that when placed
above liquid in the container a portion of the plastic layer of the
top closure and a portion of the liner are disposed adjacent to one
another at a juncture so as to form a closed structure above the
contained liquid; and wherein the top closure is sealed by bonding
the liner to the closure with the curable composition and forming a
moisture and air impermeable seal at the juncture.
2. The container of claim 1, wherein the liner is selected from a
corona treated liner, a plasma treated liner, a flame spray treated
liner or a combination thereof.
3. The container of claim 1, wherein the liner is a multilayered
plastic film.
4. The container of claim 2, wherein the lined container further
comprises a desiccant pack.
5. The container of claim 1, wherein the liquid is a composition
curable by moisture, UV radiation, heat, air or a combination
thereof.
6. The container of claim 5, wherein the liquid is a
moisture-curable polyurethane.
7. The container of claim 1, wherein the top closure is a laminate
film comprising an impermeable layer between a layer of polyester
and a layer of polyethylene.
8. The container of claim 1, wherein the liner is bonded to the
interior surface of the container prior to filling with the
liquid.
9. The container of claim 3, further comprising a patch having at
least one plastic layer and an impermeable layer, wherein the patch
is adapted cover a dispensing port located through the closure and
bond to the closure with the curable composition thereby forming a
moisture and air impermeable seal at the dispensing port.
10. The container of claim 1, wherein the sealant is a composition
including a polyurethane prepolymer.
11. A container filled with liquid comprising: a container
comprising an interior wall surface having at least one opening and
defining an enclosed cavity; a removable liner adjacent at least a
portion of the interior wall surface comprising a surface treated
plastic film, which inner liner is conformable generally with the
shape of the cavity; at least one curable composition derived from
phenolic and amino resins, acrylics, polyurethanes or epoxies
filling at least a portion of the lined structure such that a
portion of the inner liner extends beyond the liquid contained by
the container; and a top closure film comprising at least one
plastic layer and an impermeable layer; the top closure film having
a size such that when placed above liquid in the container a
portion of the plastic layer of the top closure and a portion of
the liner are disposed adjacent to one another at a juncture so as
to form a closed structure above the contained liquid; and wherein
the top closure is sealed by bonding the liner to the closure with
the curable composition and forming a moisture and air impermeable
seal at the juncture.
12. The container of claim 11, wherein the liner is a multilayered
film.
13. The container of claim 11, wherein the liner includes a metal
layer.
14. The container of claim 13, wherein the top closure is a
laminate film comprising an impermeable layer between a layer of
polyester and a layer of polyethylene.
15. The container of claim 11, further comprising a patch having at
least one plastic layer and an impermeable layer, wherein the patch
is adapted cover a dispensing port located through the closure and
bond to the closure with the curable composition thereby forming a
moisture and air impermeable seal at the dispensing port.
16. The container of claim 15, wherein the sealant is a composition
including a polyurethane.
17. A container filled with liquid comprising: a metal container
comprising an interior wall surface having at least one opening and
defining an enclosed cavity; a removable liner adjacent at least a
portion of the interior wall surface comprising a surface treated
polyolefin film, which inner liner is conformable generally with
the shape of the cavity, the liner being selected from a corona
treated liner, a plasma treated liner, a flame spray treated liner
or a combination thereof; a moisture curable polyurethane
composition filling at least a portion of the lined structure such
that a portion of the liner extends beyond the moisture curable
polyurethane composition contained in the container; and a top
closure film comprising at least one plastic layer and an
impermeable layer; the top closure film having a size such that
when placed above liquid in the container a portion of the plastic
layer of the top closure and a portion of the liner are disposed
adjacent to one another at a juncture so as to form a closed
structure above the contained liquid; and wherein the top closure
is sealed by bonding the liner to the closure with the curable
polyurethane composition and forming a moisture and air impermeable
seal at the juncture.
18. The container of claim 17 wherein the container further
comprises a desiccant located in a headspace region within the
container and above the top closure film.
19. The container of claim 17, wherein the liner is a multilayered
film.
20. The container of claim 19, wherein the top closure is a
laminate film comprising an impermeable layer between a layer of
polyester and a layer of polyethylene.
21. The container of claim 17, further comprising a patch having at
least one plastic layer and an impermeable layer, wherein the patch
is adapted cover a dispensing port located through the closure and
bond to the closure with the curable composition thereby forming a
moisture and air impermeable seal at the dispensing port.
Description
CLAIM OF PRIORITY
[0001] This invention claims the benefit of U.S. Provisional
Application 60/531,051 filed on Dec. 19, 2003.
TECHNICAL FIELD
[0002] This invention relates to a container, particularly a
container for shipping liquids, and to a method for protecting a
liquid from the environment during shipping.
BACKGROUND OF THE INVENTION
[0003] Many liquid resin or adhesive systems such as
moisture-curable polyurethane polymers (e.g., sealant primers) or
polyurethane prepolymers solidify or cure upon exposure to air or
moisture. Therefore, it is desirable to minimize contact between
these liquids and the environment prior to their end-use
application. While exposure to the environment is more or less of a
problem depending on the liquid resin or adhesive system employed,
the problems associated with premature contact with the environment
are aggravated by long periods between preparation of the liquid
resin or adhesive and its actual use. This is particularly acute
when the liquid resin or adhesive is shipped over long distances or
is maintained in the shipping container for long periods of time
prior to use.
[0004] In a conventional operation, the liquid resin or adhesive is
placed in a metal drum, commonly a 55 gallon or larger drum, often
lined with a plastic film to prevent corrosion and contamination of
both the drum and the liquid. The drum is covered with a metal or
plastic-coated metal top having approximately the same size as the
drum body which is locked to the drum using a locking collar or
bung. In various environments, the means for securing the metal lid
or top to the drum body is not particularly effective in preventing
the contact of the environment with the drum contents. As such,
portions of the liquid resin or adhesive solidify or cure and, upon
removal, the solid or cured material is removed with the liquid;
thereby introducing impurities into the finished article. It may
also be necessary to clean the drum after each use. Further, drum
disposal presents a possible waste management issue.
[0005] U.S. Pat. No. 5,507,409, herein incorporated by reference,
discloses one improved approach to the manufacturing of containers
suitable for storing and transporting moisture curable liquids. To
help prevent leakage, or curing of the liquids, the inner liner and
top closure include a multi-layered liner structure that preferably
employs a metal foil layer. It would be desirable to employ a liner
that performs at least as effectively as the liner of the above
patent, but which also has an attractive structure for reducing
overall cost of materials and manufacturing.
SUMMARY OF THE INVENTION
[0006] The present invention fulfills the above need by providing a
container having a liner of improved structure, which need not
employ a metal foil layer. Thus, one preferred aspect the present
invention contemplates a lined container that includes a container
for at least one curable composition derived from phenolic and
amino resins, acrylics, polyurethanes or epoxies and an interior
wall surface having at least one opening defining an enclosed
cavity. The container includes a removable liner adjacent to at
least a portion of the interior wall surface, which includes (and
in one particular embodiment consists essentially of) a surface
treated plastic layer generally conformable to the shape of the
cavity. The container further includes a top closure cover, which
includes at least one plastic layer and an impermeable layer. The
cover has a size such that when placed above liquid in the
container a portion of the plastic layer of the top closure and a
portion of the liner are disposed adjacent to one another at a
juncture so as to form a closed structure above the contained
liquid. As such, the cover is sealed by bonding the liner to the
cover with the curable composition and forming a moisture and air
impermeable seal at the juncture.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a cross-sectional representation of one
illustrative embodiment of the present invention.
[0008] FIG. 2 is an enlarged view of a portion of the embodiment
shown in FIG. 1.
[0009] FIG. 3 is a cross-sectional view of another embodiment of
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0010] With reference to FIGS. 1-3, in general, the present
invention is predicated upon the discovery of an improved structure
for a lined container assembly 10, particularly on that employs a
container 12 lined with surface treated plastic liner 14 that is
bonded to a cover 16 (such as a laminate top disk that optionally
includes a contents filling hole that is ultimately covered by a
patch 18), by using the material being packaged (in at least a
partially cured state) as a bonding agent 20 within a bonding
region 22. In one embodiment, the resultant bond strength from use
of the bonding agent is sufficient so that cohesive failure would
occur in the liner prior to delamination of the liner from the
bonding agent.
[0011] By use of the present invention, a resulting container
assembly including a liner can be realized in which sufficient
moisture barrier protection for the contained product is made
possible throughout its shelf life. Cured material remains a part
of the liner and is thus substantially prevented from being drawn
into drum emptying equipment, and is also potentially free of a
metal layer.
[0012] The liners of the present invention offer the potential to
realize one or more of a number of advantages over liners that
employ a metal layer. For example, the omission of a metal layer
could help to reduce the cost of materials to make the liner. The
omission of a metal layer offers the ability to reduce film density
and thus lighten liner weight. The avoidance of metals also helps
reduce manufacturing waste and also potentially affords an
advantage in enabling reclamation of the plastic of the liner
without the need to treat the metal. Other possible advantages will
be recognizable from the following description.
[0013] In general, the preference is for the liner to be made of
thermoplastic film, examples of which are selected from polyesters,
polyolefins, cellulose, vinyls (e.g., polyvinyl chlorides,
polyvinyl acetates, combinations thereof, or otherwise),
thermoplastic elastomers, polyamides, polyimides, polycarbonates,
or any combination thereof. Specific examples of films are selected
from polyethylene, polypropylene, or a combination thereof, and may
be high density type, medium density type, low density type or any
combination thereof. By way of example, as desired, films may be at
least partially oriented, crystalline, linear, branched,
copolymerized, blended, transparent, opaque, colored, coated (e.g.,
with a heat sealable coating around peripheral edges), include an
embedment, or any combination thereof. The films may include a
printed layer. The films may be a monolayer or may include multiple
layers, for example, as a co-extrudate. In another aspect of the
invention, it is contemplated that a metal layer is employed as
well, which layer might be sandwiched between opposing plastic
layers, or applied over an external plastic surface.
[0014] One particularly preferred liner of the present invention is
characterized as having at least one or both of the following
properties:
[0015] 1) a bonding region that has a surface energy (throughout
substantially the entire storage life of a stored liquid) on the
side of the film that is to be in contact with the stored liquid of
at least about 38 dynes (e.g., at least about 40 dynes, at least
about 42 dynes, or at least about 44 dynes), or higher; or
[0016] 2) a water vapor transmission rate (per ASTM-1434) up to
about 0.05 g/100 in.sup.2/24 hours at 30.degree. C./80% relative
humidity; and more preferably less than about 0.03 g/100
in.sup.2/24 hours at 30.degree. C./80% relative humidity (e.g.,
less than about 0.02 or even 0.01 g/100 in.sup.2/24 hours at
30.degree. C./80% relative humidity).
[0017] As indicated, in one example of the present invention, the
liner is also used in combination with a cover (e.g., top disk), a
patch or a combination thereof, such as disclosed in U.S. Pat. No.
5,507,409, hereby incorporated by reference. In such instances, one
very specific example contemplates that the cover, the patch or
both further exhibit a water vapor transmission rate (per
ASTM-1434) up to about 0.03 g/100 in.sup.2/24 hours at 30.degree.
C./80% relative humidity; and more preferably less than about 0.01
g/100 in.sup.2/24 hours at 30.degree. C./80% relative humidity
(e.g., less than about 0.005 or even 0.001 g/100 in.sup.2/24 hours
at 30.degree. C./80% relative humidity.
[0018] It has been found in particular that advantages of the
present invention may be realized by the employment as the liner
material a film that is surface treated over at least the bonding
region 22 for achieving a surface energy (enduring throughout
substantially the entire expected storage life of a stored liquid)
on the side of the film that is to be in contact with the stored
liquid of at least about 38 dynes (e.g., at least about 40 dynes,
at least about 42 dynes, or at least about 44 dynes), or higher.
Any of a number of techniques may be employed, particularly a
technique selected from a technique that alters the molecular state
of a polymer in the film, a technique that bonds a material having
the desired surface characteristic to the film, or a combination
thereof. By way of specific example, one or any combination of a
suitable corona treatment, flame spray treatment, or surface
coating treatment may be employed.
[0019] In another aspect of the invention, a lid 24 may be employed
to enclose the contents of the container. In one particular
application in which a lid is employed (though possible also
without employment of a lid), it is contemplated further that there
is employed a mechanism or device for absorbing or redirecting
humidity away from the packaged contents. By way of example, one or
a plurality of desiccant packs 26 (e.g., a desiccant package
including an approximately 82 gram molecular sieve) may be
contained in a headspace region 28 of the container.
[0020] The container itself may be any suitable material capable of
supporting the weight of the contents, and also preferably being
substantially corrosion resistant and substantially resistant to
degradation caused by contents of the container. Any suitable size
or shape may be employed. Examples of a common container suitable
for use in the present invention include typical 55 gallon (200 l)
cylindrical drums, e.g., plastic drums, metal drums such as chimed
steel drums, or otherwise. The containers may include any suitable
lid, such as a container lid comprising a Standard 200-liter steel
drum lid with a suitable seal, such as an approximately 12 mm
diameter (1/2") diameter sponge rubber gasket. The lid 24 may be
any suitable material, such as metal, plastic, ceramic, plastic,
coated metal or otherwise. Any suitable hardware may be used to
secure the lid to the container, such as using an art disclosed
locking collar or bung.
[0021] One specific example of an assembly herein includes
providing a liner that includes an approximately 0.08 mil
Corona-treated low density polyethylene film, which is surface
treated to approximately 50 Dynes. The cover and the patch each are
preferably tri-laminates, including at least one gas impermeable
layer such as a metal layer. For example, a preferred approach is
to employ a polyethylene film and a polyester film and a layer of
aluminum foil sandwiched therebetween.
[0022] According to one method of the present invention, a liner is
inserted into a container to be filled with at least one curable
liquid composition derived from phenolic and amino resins,
acrylics, polyurethanes or epoxies. The liquid composition is
introduced into the liner through an opening (if employed) in the
cover, and the cover is placed over the liquid. Though depicted in
the drawings and taught in U.S. Pat. No. 5,507,409 as having a
portion of the liner that extends beyond the liquid level in the
container, when filling the liquid level can be brought to
substantially the same height as the topmost part of the liner.
[0023] Moisture from ambient air cures the liquid where exposed in
a bonding region to cause the liquid to bond the cover to the
liner. The patch is likewise attached over the opening in the cover
and sealed by exposure of the liquid to ambient moisture in the
vicinity of the patch periphery. A desiccant pack optionally may be
removably or securingly attached to the patch, the cover, the
container, a container lid or any combination thereof. The
container lid is secured to the container, with a suitable seal
therebetween. As desired, at any point in the filling operation,
the cover of the liner may be smoothed or flattened using a
suitable secondary device or gas pockets evacuated, and optionally
packaged liquid is pushed into the contact area between the cover
and the liner to help aid in achieving suitable bonding in the bond
region. Any means of pushing or forcing a portion of the bonding
agent, such as use of an automated, appropriately shaped structure
wherein air or hydraulic pressure is used to apply the pressure to
form a seal of desired thickness.
[0024] Many variations of the present invention are possible. For
example, the liner can be prepared having a base such as described
in U.S. Pat. No. 3,940,052 or having a base portion which is
thicker than its side portions such as described in U.S. Pat. No.
4,347,948 (both of which are incorporated herein by reference).
[0025] As indicated, one preferred approach is to cure a portion of
the packaged contents of the container to join the cover with the
liner. However, another alternative sealant may also be used, as
will be discussed. Curing may be by any suitable mechanism, and
typically will employ exposure to elevated temperature, radiation
(e.g., UV radiation, IR radiation, radio waves, or combinations
thereof), moisture, air, any combination thereof or otherwise. In
general, it is preferred if the bonding agent will cure within a
few seconds to sufficiently bond the liner to the cover, or attach
any patch. If necessary, during curing, the liner, the cover, the
patch or all of them are physically held in a fixed desired
position.
[0026] Preferably, the cured bonding agent will form a seal that is
at least about 1 to 2 mils, i.e. 0.001 inches or millimeters, thick
and is generally evenly distributed in the juncture between the
liner and cover so as to form an air-tight seal.
[0027] The juncture of the liner and the cover might be cured prior
to, contemporaneously with or subsequent to filling. In addition to
any opening that might be employed for filling, there may be other
openings, such as an opening that can be later exposed for removal
of liquid from the container. Thus plural patches may also be
employed. Other approaches to filling, such as filling from the
bottom are also possible. Further, though the cover is depicted on
a top portion of the assembly, it can be located elsewhere, e.g. on
the sidewall, on the base or otherwise.
[0028] With regards to the various components employed in the
present invention, as indicated the container can take almost any
form and size and be made from essentially any material, provided
the structure provides a cavity to contain the liquid and the
material provides sufficient structural integrity during shipping
and storage to prevent damage and loss of the contained liquid. In
general, as discussed earlier, the container is advantageously a
conventional container for shipping liquids such as a metal, fiber,
paperboard, plastic container, e.g., a 40- to 60-gallon drum or
smaller pail such as a 5-gallon metal pail or bucket, or a
cartridge such as a caulking gun cartridge, although larger as well
as smaller capacity containers can be employed depending on the
amount of liquid to be shipped, stored or both.
[0029] As also indicated previously, it is preferred in various
embodiments to employ one or more films, such as a polyolefin film,
and particularly a film made from a polymer or copolymer of
ethylene, i.e., a polymer derived solely from ethylene or ethylene
and one or more monomers copolymerizable therewith. Such polymers
(including raw materials, their proportions, polymerization
temperatures, catalysts and other conditions) are well-known in the
art and are described, without limitation in U.S. Pat. No.
5,507,409 (incorporated by reference).
[0030] Likewise, suitable methods for the preparation of high
density polyethylene, low density polyethylene, and linear low
density polyethylene polymers are also well-known in the art and
are described, without limitation in U.S. Pat. No. 5,507,409
(incorporated by reference).
[0031] In general, high density polyethylene (HDPE) has a density
of at least about 0.94 grams per cubic centimeter (g/cc) (ASTM Test
Method D 1505). HDPE is commonly produced using techniques similar
to the preparation of linear low density polyethylene. When HDPE is
employed in the practice of the present invention, it preferably
has a density from about 0.96 to about 0.99 g/cc and a melt index
from about 0.01 to about 35 grams per 10 minutes as determined by
ASTM Test Method D 1238.
[0032] Low density polyethylene ("LDPE") is generally comprised of
highly branched chains with a density of less than about 0.94,
generally from about 0.91 to about 0.94 grams per cubic centimeter
(g/cc) (ASTM D 792). Illustrative of techniques for preparing LDPE
are described in U.S. Pat. Nos. 3,756,996 and 3,628,918.
[0033] Any polyethylene film employed is preferably heat sealable
and is more preferably an essentially pinhole free or pinhole free,
low density, heat-sealable polyethylene. In one specific example,
the liner is a polyethylene that is low density polyethylene.
[0034] When employed, such as in the cover and any patch, a
particular gas impermeable layer will be a film layer prepared from
a material which is suitably impermeable to air or the environment
for the intended purpose. While the permeability properties of such
layer may vary depending on the liquid employed and its
susceptibility to moisture or the environment as well as the
thickness and specific composition of the polyethylene and
polyester film layers, in general, the material employed in
preparing the impermeable film layer is a material such that the
inner liner and top laminate film have a gas transmission of less
than about 0.5 cc, preferably less than 0.2 cc, more preferably
less than 0.15 cc per 100 square inches (645.16 square centimeters)
in a 24 hour period (ASTM-1434). Most preferably, the gas
permeability is less than about 0.1 cc/100 in.sup.2/24 hours. In
addition, the barrier layer is prepared from a material which is
compatible or which can be made compatible with the polyethylene
and polyester layers, i.e., the gas impermeable barrier layer can
be prepared as a laminate with the polyethylene and polyester
layers, such as using an adhesive between one or more of the layers
(e.g., the aluminum foil and low density polyethylene) or by
coextruding a polyethylene layer between the polyester and metal
foil layer. While certain polymers such as vinyl chloride polymers
can be employed as the barrier layer, in general, a metal foil or
metalized polymer film is most advantageously employed as the
impermeable layer. A preferred metal for use as the impermeable
layer is aluminum, more preferably an essentially pinhole free or
pinhole free, dead-soft, aluminum foil.
[0035] When employed, the polyester layer is a film made from a
polyester material. Polyesters and methods for their preparation
(including the specific monomers employed in their formation, their
proportions, polymerization temperatures, catalysts and other
conditions are well known in the art and described in U.S. Pat. No.
5,507,409 (incorporated by reference).
[0036] Metalized polymer films comprise a plastic film having a
thin metal on a surface. The metal layer is generally deposited on
the film surface as a metal vapor layer in a vacuum. A preferred
metal is aluminum, though other metals may also be employed.
Preferred plastic film comprises polyether polycarbonates, nylons
and polypropylene. The preferred films comprise polyesters.
[0037] The thickness of the top and inner film layers as well as
each layer in a laminate herein are dependent on a number of
factors including the liquid being shipped or stored in the
container, the length of shipping and storage prior to use, and the
specific composition employed in each layer of the laminate.
[0038] In general, the liner will have a total thickness of from
about 7 to about 2000 microns, preferably from about 25 to about
500 microns; with the thickness of the polyethylene layer being
from about 5 to about 750 microns, preferably from about 10 to
about 300 microns; the thickness of the polyester layer being from
about 1 to about 250 microns, preferably from about 5 to about 100
microns and the thickness of the barrier layer being from about 1
to about 100 microns, preferably from about 5 to about 50 microns
when the barrier layer is a metal foil.
[0039] In general, the top laminate film will have a total
thickness of from about 16 to about 1000 microns, preferably from
about 20 to about 250 microns, with the thickness of the
polyethylene layer being from about 10 to about 500 microns,
preferably from about 25 to about 200 microns; the thickness of the
polyester layer being from about 5 to about 200 microns, preferably
from about 15 to about 100 microns; and the thickness of the
barrier layer being from about 1 to about 100 microns, preferably
from about 5 to about 50 microns when the barrier layer is a metal
foil.
[0040] The bonding agent employed preferably will be material of
the type that is packaged in the container. In general, any
material which reduces permeability of the environment and which
sufficiently acts to bond the materials to one another can be
employed and selection of the material which is most advantageous
will be dependent on a variety of factors including the contained
liquid and its susceptibility to moisture and/or air, the specific
inner and top laminate layers employed, and the expected duration
of shipping and storage. Other representative examples of materials
which can be employed as the bonding agent include hot melt
adhesive such as hot melt adhesives based on polyester, polyamides
or block copolymer rubbers; adhesives which are applied from
solution or dispersion such as phenolics and amino resins which can
be applied from water solution, or acrylics or polyurethanes which
can be applied from organic solutions, or epoxies applied from
aqueous dispersion. An adhesive which can be applied dry and then
activated such as by exposure to water or an organic solvent can
also be employed. In addition, pressure sensitive adhesives can
also be employed. Preferred sealants are those materials which have
good shelf life in the absence of air or moisture but which cure
rapidly upon exposure to moisture or air.
[0041] Examples of particularly preferred bonding agents are
moisture-curable polyurethanes, such as described in U.S. Pat. Nos.
4,758,648; 4,780,520; and 5,086,151 (all incorporated by
reference). These agents comprise a polyurethane prepolymer (an
isocyanate terminated reaction product of an organic polyisocyanate
with a polyhydroxy compound, preferably having an isocyanate
functionality of between 2.3 and 3.0) and a catalyst useful for
promoting the reaction of isocyanate groups with water. See also
U.S. Pat. No. 5,507,409 (incorporated by reference).
[0042] Prior to filling the container, the cover film is put in
place and the container filled from the bottom. Upon completion of
filling, the impermeable bonding agent is cured by its exposure to
air, thereby gluing the top laminate and inner liner together to
produce an air impermeable seal. Alternatively, the bonding agent
is applied to either or both of the cover or liner, at which time
the films are bonded together and the bonding agent being exposed
to moisture, bonds the films. In one embodiment, once applied from
the moisture-free environment onto the inner and/or top laminate
film, the sealant will effectively cure within about 30 seconds to
about 300 minutes, and more particularly from about 1 to about 30
minutes.
[0043] It will be further appreciated that functions or structures
of a plurality of components or steps may be combined into a single
component or step, or the functions or structures of one step or
component may be split among plural steps or components.
Alternatively, functions performed by one of the components might
be split among or performed by other components. The present
invention contemplates all of these combinations. Unless stated
otherwise, quantities, dimensions and geometries of the various
structures depicted herein are not intended to be restrictive of
the invention, and others are also possible. In addition, while a
feature of the present invention may have been described in the
context of only one of the illustrated embodiments, such feature
may be combined with one or more other features of other
embodiments, for any given application.
[0044] The explanations and illustrations presented herein are
intended to acquaint others skilled in the art with the invention,
its principles, and its practical application. Those skilled in the
art may adapt and apply the invention in its numerous forms, as may
be best suited to the requirements of a particular use.
Accordingly, the specific embodiments of the present invention as
set forth are not intended as being exhaustive or limiting of the
invention. The scope of the invention should, therefore, be
determined not with reference to the above description, but should
instead be determined with reference to the appended claims, along
with the full scope of equivalents to which such claims are
entitled. The disclosures of all articles and references, including
patent applications and publications, are incorporated by reference
for all purposes.
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