Abstrict A substantially solvent-free molten or fluid desiccant/organic
matrix composition is adhered to a package whereby the desiccant
is in communication with a compartment of the resulting package
such that the compartment is desiccated by the desiccant composition.
The desiccant composition preferably contains a thermoplastic organic
matrix, is heated before it is adhered to the package, and cools
after application. In some instances, the desiccant matrix may be
adhered to a component of the package contents. The package is preferably
non-reclosable and suitable for holding an article such as a drug,
medical device or electronic device.
Claims What is claimed is:
1. A method of preparing a desiccated package in an automated,
continuous manufacturing process, said packaging having a compartment
being adapted to contain an article or substance in a sealed environment,
said method comprising (a) preparing a composition comprising desiccant
and organic matrix wherein the organic matrix comprises thermoplastic
resin, (b) applying the desiccant/organic matrix composition as
a substantially solvent-free fluid composition to a portion of the
package to which the desiccant/organic matrix composition is adhered
with substantially no stringing, (c) completing the formation of
said compartment, (d) filling the package with the article and (e)
sealing said compartment whereby said desiccant is in communication
with said compartment such that said compartment is desiccated,
and wherein steps (b) through (e) are conducted in a continuous
fashion.
2. The method of claim 1 wherein said organic matrix comprises
a polyolefin resin.
3. The method of claim 1 wherein said desiccant/organic matrix
composition is heated before it is applied and adhered to said package
and said composition cools after said adhesion.
4. The method of claim 1 wherein said package is formed from one
or more continuous webs having surfaces which define said compartment
and said desiccant/organic matrix composition is adhered to one
or more of said surfaces.
5. The method of claim 1 wherein said compartment is sealed after
said desiccant/organic matrix composition is adhered to said package.
6. The method of claim 1 wherein said package comprises at least
two sealed compartments which communicate with each other wherein
the desiccant/organic matrix composition is adhered to the interior
of one of said compartments and the other compartment is desiccated
by said composition.
7. The method of claim 1 wherein the fluid composition in (b) flows
through an orifice and the composition is adhered to the package
after passage through the orifice.
8. The method of claim 7 wherein pressure is applied to the composition
to accelerate flow of the composition through the orifice.
9. The method of claim 1 wherein the desiccant is selected from
the group consisting of silica gels, zeolites, silica aluminas,
non-zeolite molecular sieves, activated carbon, and mixtures thereof.
10. The method of claim 1 wherein a non-reclosable package is prepared.
11. A method according to claim 1 wherein the desiccant/organic
matrix composition comprises at least 15% by weight desiccant.
12. A method according to claim 1 wherein the desiccant/organic
matrix composition comprises at least 20-80% by weight desiccant.
13. A method according to claim 1 wherein the desiccant/organic
matrix composition comprises at least 30-60% by weight desiccant.
14. A method according to claim 1 wherein the thermoplastic resin
has a Brookfield melt viscosity of 75-200 centipoise at 125.degree.
C. and shear rate of 34 sec.sup.-1.
15. A method according to claim 1 wherein the thermoplastic resin
has a Brookfield melt viscosity of 2000-4500 centipoise at 190.degree.
C. and shear rate of 34 sec.sup.-1.
16. A method of preparing a desiccant package in an automated,
continuous manufacturing process, said package housing a compartment
being adapted to contain an article in a sealed environment, said
method comprising (a) preparing a composition comprising desiccant
and organic matrix wherein the organic matrix comprises a thermoplastic
resin, (b) applying the desiccant/organic matrix composition as
a substantially solvent-free fluid desiccant/organic matrix composition
to a portion of the article to which the desiccant/organic matrix
composition is adhered with substantially no stringing, (c) completing
the formation of the compartment whereby the article having the
adhered desiccant composition is located in the compartment, and
(d) sealing the article-containing compartment whereby the desiccant
is in communication with the compartment such that the compartment
is desiccated, and wherein steps (b) through (d) are conducted in
a continuous fashion.
17. The method of claim 16 wherein the article is a carrier device
for one or more other articles or substances.
18. The method of claim 16 wherein a non-reclosable package is
created by said sealing.
19. A non-reclosable package having at least one non-reclosable
sealed compartment adapted to contain an article or substance wherein
said package contains desiccant composition comprising a desiccant
in an organic matrix comprising thermoplastic resin, said desiccant
composition being adhered to said package wherein substantially
no strings of resin extend from the desiccant composition and the
desiccant composition is in communication with said compartment
and whereby said compartment is desiccated by said desiccant composition.
20. The package of claim 19 wherein said package comprises a plurality
of said compartments.
21. The package of claim 19 wherein said organic matrix comprises
a thermoplastic polyolefin resin.
22. The package of claim 19 wherein said desiccant is selected
from the group consisting of silica gels, zeolites, silica aluminas,
non-zeolite molecular sieves, activated carbon and mixtures thereof.
23. The package of claim 19 wherein said desiccant comprises zeolite
3A.
24. The package of claim 19 wherein said desiccant comprises a
combination of zeolite 3A with either zeolite 13X or silica gel.
25. The package of claim 21 wherein said polyolefin resin is a
polyethylene wax.
26. The package of claim 25 wherein said polyethylene wax has a
weight average molecular weight of 3000-5000.
27. The package of claim 19 wherein said desiccant composition
is adhered to a portion of an interior surface of said compartment.
28. The package of claim 19 wherein said package comprises an additional
compartment in communication with said sealed compartment wherein
said desiccant composition is adhered to an interior portion of
said additional compartment.
29. The package of claim 19 wherein said sealed compartment is
adapted to contain at least one article selected from the group
consisting of tablets, pills, capsules, gel caps, lozenges or mixtures
thereof.
30. The package of claim 19 wherein said sealed compartment is
adapted to contain a medical device or diagnostic test kit.
31. The package of claim 19 wherein said package is adapted to
contain an electronic device.
32. The package of claim 19 wherein said sealed compartment is
defined by a cavity in a continuous flexible web and a cover sheet
which is sealed against said cavity-containing web at the perimeter
of said cavity.
33. The package of claim 32 wherein said cover sheet is heat sealed
against said web.
34. The package of claim 19 wherein said sealed compartment is
a pouch.
35. A package of claim 19 wherein the desiccant composition comprises
at least 15% weight desiccant.
36. A package of claim 19 wherein the desiccant composition comprises
at least 20-80% weight desiccant.
37. A package of claim 19 wherein the desiccant composition comprises
at least 30-60% weight desiccant.
38. A non-reclosable package having at least one non-reclosable
sealed compartment which contains an article wherein a desiccant
composition comprising a desiccant in an organic matrix comprising
thermoplastic resin is adhered to said article whereby there are
substantially no strings of resin extending from the desiccant composition
and said compartment is desiccated by said desiccant composition.
39. The package of claim 38 wherein said article is a carrier device
for one or more other articles or substances.
40. The method of claim 1 wherein the thermoplastic resin is polyolefin.
41. The method of claim 16 wherein the thermoplastic resin is polyolefin.
42. The method of claim 38 wherein the thermoplastic resin is polyolefin.
Description BACKGROUND OF THE INVENTION
The packaging drugs, pharmaceuticals, medical devices, electronics
and other articles in non-reclosable packaging has become widespread
and continues to grow especially with advances in materials and
automated packaging equipment (e.g. form/fill/seal machinery, fill/seal
machinery, etc.). Today, many over-the-counter drugs (tablets, pills,
capsules, gel caps, lozenges, etc.), medical devices, diagnostic
test kits, and equipment are packaged in so-called "blister
packs."
With these advances in packaging, the ability to effectively provide
a desiccated package environment has often been difficult because
conventional desiccant forms (e.g. pouches, sachets, tablets) are
not suitable for use in high speed packaging operations. Conventional
desiccant forms may also create problems to the extent that they
are not adhered to or are easily detached from the packaging. Thus,
conventional forms of desiccants may be problematic where the package
is designed to contain comestibles in as much as the desiccant may
be accidentally ingested by the consumer.
Conventional desiccants are also problematic in that it is difficult
to associate an appropriate amount of desiccant with a particular
package environment. While conventional desiccant forms come in
different sizes, the range of sizes is fairly limited and is constrained
by the need for the desiccant to be in a manageable form. Conventional
desiccant forms may also adversely affect the appearance of the
package.
There have been some packaging applications where the use of polymer
bound desiccants. Unfortunately, this use has generally involved
the use of solvents or vehicles which must be evaporated before
closure of the package. Needless to say, systems requiring evaporation
of solvents are virtually unworkable for high speed automated packaging
processes where the time between filling and sealing is extremely
short. Such systems also present problems relative to food/drug
packaging where in the materials may require government approval.
Thus, there is an need for alternative desiccant forms and application
techniques for non-reclosable and other packaging applications.
SUMMARY OF THE INVENTION
The invention provides alternative desiccant forms and techniques
for incorporation of desiccants into modern-day packaging, especially
non-reclosable packaging.
In one aspect, the invention encompasses a method of adhering a
substantially solvent-free molten or fluid desiccant/organic matrix
composition to a package whereby the desiccant is in communication
with a compartment of the resulting package such that the compartment
is desiccated by the desiccant composition. The method preferably
uses a thermoplastic organic matrix. The desiccant matrix composition
is preferably heated before it is adhered to the package and cools
after application. In some instances, the desiccant matrix may be
adhered to a component of the package contents.
In another aspect, the invention encompasses non-reclosable packages
having at least one non-reclosable sealed compartment adapted to
contain an article or substance wherein the package contains a desiccant
composition comprising a desiccant in an organic matrix, the desiccant
composition being adhered to a portion of the package and being
in communication with the compartment whereby the compartment is
desiccated by the desiccant composition. The organic matrix preferably
comprises a thermoplastic resin. The desiccant composition preferably
is essentially solvent-free. The package compartment is preferably
suitable for holding an article such as a drug, medical device or
electronic device. In some instances, the desiccant composition
may be adhered to a component of the package contents.
The invention is especially useful for the packaging of one-time-openable
non-reclosable packaging (blister packs, tear open pouches, etc.).
These and other aspects of the invention are described in further
detail below.
DETAILED DESCRIPTION OF THE INVENTION
The invention encompasses methods of providing desiccant functionality
to a package via a desiccant/organic matrix composition. The methods
of the invention are preferably characterized by the absence of
solvents (e.g. water, organic solvent). The methods of the invention
preferably are characterized by the adhering a heated, thermoplastic
desiccant/organic matrix composition to the package. The invention
is especially useful for automated packaging operations and for
non-reclosable packages. The invention is also especially useful
in one-time-openable non-reclosable packaging (e.g. blister packs,
tearable pouches) for drugs, pharmaceuticals, foods, and consumer
products.
"Non-reclosable" is meant to include all packages and
containers where a compartment of the package or container adapted
to contain the desired article or substance can not be reclosed
after opening without some physical alteration of the package. Conventional
pill bottles with snap or screw caps would be considered as reclosable
packages whereas blisters in a blister pack would be considered
non-reclosable. Similarly, compartments for storing electronics
would be considered reclosable if they were held closed by reclosable
fasteners (e.g. screws) whereas a compartment which was sealed by
solder would be considered non-reclosable.
"One-time-openable" is meant to indicate that the package
or container can be opened once (after initial sealing) without
destroying the contents thereof. Thus, a blister pack having a rupturable
or peelable cover layer or web would be considered one-time-openable.
Most tearable pouches would also be considered as one-time-openable,
presuming that they do not contain an alternative sealing means
designed for use after the initial opening.
The desiccants useful in the invention may be conventional water-adsorbing
material such as zeolites, silica gels, activated carbons, silica
aluminas, non-zeolite molecular sieves, etc. Non-reactive inorganic
oxide desiccants are generally preferred. Zeolite A, especially
zeolite 3A is a most preferred water-adsorbing material. If desired,
adsorbents designed to adsorb low molecular weight organic compounds
(e.g. zeolite 13X) may be blended with the water-adsorbing material.
The organic matrix may contain various polymer components. Preferably,
the organic matrix is one which is flowable in the absence of a
solvent or dispersing vehicle. The organic matrix preferably comprises
a thermoplastic resin such that the overall desiccant/organic matrix
composition behaves as a thermoplastic. The thermoplastic resin
preferably comprises one or more polyolefin resins, e.g. polyethylene,
polypropylene, olefin copolymers, olefin terpolymers or combinations
thereof; however in some instances other thermoplastic resin systems
may also be employed. The thermoplastic resin should be such that
the resulting desiccant/organic matrix composition is capable of
flowing on heating to a temperature which is compatible with the
particular packaging operation. Further, the resin should be selected
such that the desiccant composition has the sufficient mechanical
integrity at the temperature of interest for the specific package
application. For example, if the package is expected to see exposure
to temperatures greater than ambient temperature during or prior
to use, the desiccant/organic resin composition should be able to
retain its shape and position in the package (i.e. it should not
undergo substantial flow) under the expected conditions. Preferably,
the resin system is selected such that the desiccant/organic matrix
composition can be flowed into place without any adverse effects
such as "stringers"--trails of resin coming off of the
deposited composition.
The invention is open to the use of any thermoplastic resin system
which meets the above mentioned performance criteria while also
meeting any other compositional requirements which may be involved
in the specific packaging application. The resin preferably has
a softening point (ring and ball) of about 30-200.degree. C., more
preferably about 50-150.degree. C. Where the resin is crystalline,
it preferably has a melting point of about 50-250.degree. C., more
preferably about 80-200.degree. C. For many pharmaceutical packaging
applications, resins having a Brookfield melt viscosity (@ 125.degree.
C., spindle #27100 RPM, shear rate=34 sec.sup.-1) of 75-200 centipoise
(more preferably 125-175 cP) are preferred. In other instances involving
higher temperature applications, low density polyethylene resins
having a Brookfield melt viscosity (@ 190.degree. C.) of about 2000-4500
centipoise, more preferably about 2500-3500 cP may be used. In some
circumstances, higher melt viscosity resins such as polypropylene
may also be useful. Combinations of resins may be used to tailor
the Theological properties of the desiccant/organic matrix composition.
For applications requiring high speed application through small
orifices, polyethylene waxes having a weight average molecular weight
or about 3000-5000 are preferred. All Brookfield melt viscosities
specified herein were measured with a Brookfield Thermosel, model
HBDV-III apparatus.
If necessary, the organic matrix may contain up to about 30 wt.%
(more preferably 0-15%) of a tackifier resin based on the total
weight of all resins in the desiccant matrix composition. Preferred
tackifiers are butene-1 propylene copolymer (REXTAC RT 2715 from
Rexene Corp.) or blends thereof with other commercial tackifier
resins. The organic matrix may also contain auxiliary components
such as coloring agents, scents, lubricants, stabilizers, etc. For
most applications, auxiliary components are kept to a minimum or
are avoided entirely.
The relative amount of desiccant component in the desiccant/organic
matrix composition may be varied considerably, depending on the
desired adhesive and/or rheological properties of the composition,
the adsorption capacity of the desiccant component, the desired
adsorption capability in the package environment, etc. In general,
the desiccant/organic matrix compositions used in the invention
preferably contain at least about 15 wt. % desiccant, more preferably
about 20-80%, most preferably about 30-60 wt. %. Where an adsorbent
for removing low molecular weight organic volatiles is also used,
preferably the combination of the desiccant and such organic adsorbent
fall within the above ranges. Preferably the organic adsorbent represents
less than about 10 wt. % of the total of desiccant and organic adsorbent.
The desiccant/organic matrix composition of the invention may be
formed using conventional compounding techniques. For example, the
components can be simply loaded into a kneader extruder, twin screw
extruder or other appropriate device to obtain the composition with
the desired degree of desiccant dispersion. The formation of the
desiccant/organic matrix composition is preferably characterized
by the absence of any solvent.
The desiccant/organic matrix compositions may be used in a variety
of packaging configurations and in a variety of conventional packaging
processes. Preferably, the desiccant compositions of the invention
are used in non-reclosable packaging, more preferably in one-time
openable, non-reclosable packaging. Preferred packaging techniques
are form/fill/seal and fill/seal type processes. These processes
are well known in the packaging art. See for example, "Packaging
Drugs and Pharmaceuticals" by Wilmer A. Jenkins et al., Technomic
Publishing, Lancaster, Pa., 1993 and "Medical Device Packaging
Handbook," Ed. by Joseph D. O'Brien, Marcel Dekker, Inc., New
York, 1990. Equipment for carrying out these packaging processes
is also disclosed in the journals, "Packaging Technology &
Engineering" and "Pharmaceutical & Medical Packaging
News." The disclosures of these publications is incorporated
herein by reference.
In these processes, the desiccant/organic matrix compositions of
the invention can be applied using equipment known for depositing
hot melt adhesives such as equipment manufactured by Airprint Systems
Inc., The
Dexter Corp., Nordson Corp., Spraymation, Inc. and others. See
the listing in "Packaging Technology & Engineering,"
November/December 1995 pages 10-12. Using this equipment, it is
possible to deposit the desiccant/organic matrix compositions of
the invention via spraying, rolling, extrusion, etc. A preferred
unit is the Nordson AG-900 Modular Dispensing Gun.
The general method of the invention preferably involves heating
the desiccant/organic matrix composition to a suitable temperature
in order to reduce its viscosity to a point where the composition
can be flowed using the desired application technique. For example,
where the composition is applied by extrusion on a low speed manufacturing
line, a higher viscosity may be usable compared to higher speed
manufacturing lines or where the composition is applied by spraying
or dripping. Typically, the composition will be heated to about
50-250.degree. C. to affect the necessary viscosity reduction. Once
deposited, the desiccant composition would be allowed to cool whereby
the composition becomes fixed in the desired position. Extrusion
under pressure through an orifice is generally the most preferred
application technique from the point of speed and ease of control.
The method of the invention may be practiced before, during or after
filling of the package with its desired contents. The filling and
sealing of the package may be performed using the conventional techniques
for the particular type of packaging. For most packaging applications,
a heat or adhesive sealing technique may be employed. The method
of the invention is not limited to any particular package construction
or packaging technique. The method of the invention is preferably
characterized by the absence of solvent from the desiccant/organic
matrix composition at least at the time of application, but more
preferably throughout the entire method.
In blister packaging where cavities are formed in a continuous
web for subsequent filling and sealing, the desiccant composition
of the invention is preferably extruded into either a portion of
the cavity wherein the article or substance to be packaged is placed
in the same cavity or may be placed in a separate cavity which communicates
with the cavity containing the article/substance in the final package.
Alternatively, but less preferably, the desiccant composition of
the invention may be applied (e.g. as a dot matrix) to the sheet
forming the cover for the cavities such that the desiccant composition
is present on the portions of the cover sheet which reside over
the cavities of the continuous web on the side of the cover sheet
which defines the top of the cavities.
For fill/seal processes (e.g., wherein two plastic sheets are sealed
against each other to create an envelope or tube which is subsequently
filled and sealed) the desiccant composition of the invention may
be applied to a surface of one or both sheets which surface forms
an interior surface of the envelope or tube. This is preferably
done before the envelope or tube is filled with the article or substance
to be packaged.
The desiccant compositions of the invention may be applied to other
known package configurations where a desiccating function is desired.
For example, in the packaging of electronic devices, the desiccant
compositions of the invention may be applied to the package interior
or even to an article to be contained in the package (e.g. to a
non-moving part in a magnetic disk drive). Where a carrier device
(e.g., a tray) is used to hold one or more articles in a single
compartment, the desiccant matrix composition may be adhered to
the carrier device. The carrier device would then be placed in the
compartment (e.g. two flexible webs joined together to form a pouch)
which is then sealed.
Other examples of packaging where the desiccant compositions of
the invention are useful are disclosed in U.S. Pat. Nos. 3211503;
3734283; 3343897; 4753352; 4777780; 5080225; 5223220;
5322161 and 5390475. The disclosures of these patents are incorporated
herein by reference. |