U.S. patent application number 11/010545 was filed with the patent office on 2005-06-30 for child-resistant blister package.
Invention is credited to Miller, Mark Ralph, Triplett, Edith Gottemoller.
Application Number | 20050139505 11/010545 |
Document ID | / |
Family ID | 34700064 |
Filed Date | 2005-06-30 |
United States Patent
Application |
20050139505 |
Kind Code |
A1 |
Miller, Mark Ralph ; et
al. |
June 30, 2005 |
Child-resistant blister package
Abstract
An improved child-resistant blister package is provided in which
the lidding component includes a tear-resistant nonwoven layer and
a barrier layer. The nonwoven layer can be a melt-spun continuous
filament nonwoven web or a flash spun plexifilamentary sheet. The
lidding component used in peel off-push through blister packages of
the invention contains fewer layers and has improved puncture
resistance compared to lidding components used in child-resistant
packages known in the art. In addition, in peel off-push through
and peel-open package designs of the present invention, the lidding
peels more cleanly from the blister component compared to packages
known in the art which have a tendency to tear during peeling.
Inventors: |
Miller, Mark Ralph; (Louisa,
VA) ; Triplett, Edith Gottemoller; (Midlothian,
VA) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY
LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1128
4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
34700064 |
Appl. No.: |
11/010545 |
Filed: |
December 13, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60529912 |
Dec 15, 2003 |
|
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|
Current U.S.
Class: |
206/528 |
Current CPC
Class: |
B32B 2439/00 20130101;
B65D 2575/3236 20130101; B32B 15/08 20130101; B32B 2255/20
20130101; B32B 7/12 20130101; B32B 7/06 20130101; B32B 27/12
20130101; B32B 3/30 20130101; B32B 5/022 20130101; B32B 2255/205
20130101; B32B 3/28 20130101; B65D 75/327 20130101; B65D 2215/04
20130101; B32B 27/304 20130101; B32B 2307/31 20130101; B32B 2439/80
20130101; B32B 2255/10 20130101 |
Class at
Publication: |
206/528 |
International
Class: |
B65D 083/04 |
Claims
What is claimed is:
1. A blister package comprising a blister component having an inner
surface and an outer surface and a multi-layer lidding component
having an inner surface and an outer surface, wherein selected
portions of the inner surfaces of the blister and lidding
components are adhered together to form at least one cavity
therebetween, the blister component comprising a first barrier
layer selected from the group consisting of polymeric films, coated
polymeric films, metal foils, and film-foil laminates, and the
lidding component comprising a second barrier layer and a nonwoven
layer comprising at least one melt-spun continuous filament
nonwoven sheet.
2. A blister package according to claim 1 wherein the second
barrier layer comprises a sheet layer selected from the group
consisting of polymeric films, coated polymeric films, metalized
polymeric films, and metal foils.
3. A blister package according to claim 2 wherein the lidding
component further comprises an adhesive tie layer intermediate the
second barrier layer and the nonwoven layer, and a heat-seal layer
adhered to the side of the second barrier layer opposite the
adhesive tie layer, such that the inner surface of the lidding
component comprises the heat-seal layer and the outer surface of
the lidding component comprises the nonwoven layer, and wherein the
lidding and blister components are heat sealed to each other to
form a seal therebetween.
4. A blister package according to claim 3 wherein the heat-seal
layer comprises a heat-sealable sealant selected from the group
consisting of poly(vinylidene chloride), vinyl/acrylic
compositions, blends of polyolefin resins comprising ethylene vinyl
acetate copolymers, blends of polyolefin resins comprising ethylene
methyl acrylate copolymers, and polyester-based compositions.
5. A blister package according to claim 3 wherein the tie-layer
comprises an adhesive composition selected from the group
consisting of vinyl/acrylic compositions, blends of polyolefin
resins comprising ethylene vinyl acetate copolymers, blends of
polyolefin resins comprising ethylene methyl acrylate copolymers,
ethylene vinyl acetate resins, ethylene methyl acrylate resins, and
polyester-based polyurethanes.
6. A blister package according to claim 3 wherein the seal between
the heat-seal layer and the blister component is peelable such that
the blister package can be opened by peeling the lidding component
from the blister component.
7. A blister package according to claim 6 wherein the heat-seal
layer comprises a sealant selected from the group consisting of
poly(vinylidene chloride), vinyl/acrylic compositions, blends of
polyolefin resins comprising ethylene vinyl acetate copolymers, and
blends of polyolefin resins comprising ethylene methyl acrylate
copolymers.
8. A blister package according to claim 3 wherein the second
barrier layer is frangible.
9. A blister package according to claim 8 wherein the adhesive tie
layer is a peelable layer such that the combined nonwoven and
adhesive tie layers can be peeled away from the second barrier
layer and a material packaged in the blister package can be removed
from the package after said peeling by pushing the packaged
material through the frangible barrier layer.
10. A blister package according to claim 9 wherein the adhesive tie
layer comprises an adhesive composition selected from the group
consisting of vinyl/acrylic compositions, blends of polyolefin
resins comprising ethylene vinyl acetate copolymers, and blends of
polyolefin resins comprising ethylene methyl acrylate
copolymers.
11. A blister package according to claim 9 wherein the second
barrier layer comprises a frangible sheet layer selected from the
group consisting of frangible polymeric films and frangible metal
foils.
12. A blister package according to claim 3 wherein the second
barrier layer comprises a metalized polymeric film that is
metalized on one side thereof, and wherein the metalized side of
the second barrier layer is adjacent the adhesive tie layer.
13. A blister package according to claim 3 wherein the second
barrier layer comprises a polymeric film that is coated on one side
thereof with a ceramic material, and wherein the coated side of the
second barrier layer is adjacent the adhesive tie layer.
14. A blister package according to claim 12 wherein the metalized
polymeric film comprises a metalized polyester film.
15. A blister package according to claim 14 wherein the metalized
polyester film is a poly(ethylene terephthalate) film having a
layer of aluminum metal deposited thereon.
16. A blister package according to claims 1, 9 or 14 wherein the
nonwoven layer comprises a full-surface bonded multiple component
spunbond web.
17. A blister package according to claim 13 wherein the ceramic
material is selected from the group consisting of oxides, nitrides,
and carbides of silicon, aluminum, magnesium, chromium, lanthanum,
titanium, boron, or zirconium, and mixtures thereof.
18. A blister package according to claims 1 or 2 wherein the
nonwoven layer comprises at least one meltblown web sandwiched
between first and second melt-spun continuous filament nonwoven
sheets.
19. A blister package according to claim 18 wherein the first and
second melt-spun continuous filament nonwoven sheets are multiple
component spunbond nonwoven webs.
20. A blister package according to claim 19 wherein the at least
one meltblown web is a multiple component meltblown web.
21. A blister package according to claim 20 wherein the first and
second spunbond nonwoven webs comprise bicomponent sheath-core
spunbond fibers wherein the melting point of the sheath component
is lower than the melting point of the core component by at least
10.degree. C., and the at least one meltblown web comprises
bicomponent side-by-side meltblown fibers.
22. A blister package according to claim 18 wherein the nonwoven
layer comprises a plurality of meltblown webs sandwiched between
the first and second melt-spun continuous filament nonwoven
sheets.
23. A blister package according to claim 19 wherein the nonwoven
layer is a thermally calendered nonwoven layer.
24. A blister package according to claim 23 wherein the nonwoven
layer is a full-surface bonded nonwoven layer.
25. A blister package according to claim 24 wherein the first and
second multiple component spunbond nonwoven webs comprise
sheath-core spunbond fibers wherein the core component comprises a
polyester and the sheath component comprises a polyester
copolymer.
26. A blister package according to claims 1 or 2 wherein the at
least one melt-spun continuous filament nonwoven sheet comprises a
spunbond nonwoven web.
27. A blister package according to claim 26 wherein the spunbond
nonwoven web is a multiple component spunbond nonwoven web.
28. A blister package according to claim 27 wherein the multiple
component spunbond nonwoven web comprises bicomponent spunbond
fibers comprising a sheath component and a core component, wherein
the melting point of the sheath component is lower than the melting
point of the core component by at least 10.degree. C.
29. A blister package according to claim 28 wherein the core
component comprises a polyester and the sheath component comprises
a polyester copolymer.
30. A blister package according to claim 29 wherein the core
component comprises poly(ethylene terephthalate) and the polyester
copolymer is selected from the group consisting of poly(ethylene
terephthalate) copolymers that have been modified with
1,4-cyclohexanedimethanol and poly(ethylene terephthalate)
copolymers that have been modified with di-methyl isophthalic
acid.
31. A blister package according to any of claims 27-30 wherein the
multiple component spunbond nonwoven web is a thermally calendered
multiple component spunbond nonwoven web.
32. A blister package according to claim 31 wherein the thermally
calendered multiple component spunbond nonwoven web is a
full-surface bonded spunbond nonwoven web.
33. A blister package according to claim 1 wherein the second
barrier layer is a heat-sealable barrier layer adhered to the
nonwoven layer, the inner surface of the lidding component
comprises the heat-sealable barrier layer, and the lidding and
blister components are heat sealed together to form a seal
therebetween.
34. A blister package according to claim 33 wherein the seal is a
peelable seal such that the blister package can be opened by
peeling the lidding component from the blister component.
35. A blister package according to claim 33 where in the seal is a
non-peelable seal and the blister package further comprises at
least one notch located internal to the package or on an external
edge of the package.
36. A blister package according to claim 34 or 35 wherein the
heat-sealable barrier layer comprises poly(vinylidene
chloride).
37. A blister package according to claim 34 or 35 wherein the at
least one melt-spun continuous filament nonwoven sheet comprises a
full-surface bonded multiple component spunbond nonwoven web.
38. A blister package comprising a blister component having an
inner surface and an outer surface and a multi-layer lidding
component having an inner surface and an outer surface, wherein
selected portions of the inner surfaces of the blister and lidding
components are bonded together to form at least one cavity
therebetween, the blister component comprising a first barrier
layer selected from the group consisting of polymeric films, coated
polymeric films, metal foils, and film-foil laminates, and the
lidding component comprising a flash spun plexifilamentary sheet
and a second barrier layer comprising a sheet layer selected from
the group consisting of polymeric films, coated polymeric films,
and metalized polymeric films.
39. A blister package according to claim 38 wherein the lidding
component further comprises an adhesive tie layer intermediate the
second barrier layer and the flash spun plexifilamentary sheet, and
a heat-seal layer adhered to the side of the second barrier layer
opposite the adhesive tie layer, such that the inner surface of the
lidding component comprises the heat-seal layer and the outer
surface of the lidding component comprises the flash spun
plexifilamentary sheet, and wherein the lidding and blister
components are heat sealed to each other to form a seal
therebetween.
40. A blister package according to claim 39 wherein the heat-seal
layer comprises a heat-sealable sealant selected from the group
consisting of poly(vinylidene chloride), vinyl/acrylic
compositions, blends of polyolefins comprising ethylene vinyl
acetate copolymers, blends of polyolefin resins comprising ethylene
methyl acrylate copolymers, and polyester-based compositions.
41. A blister package according to claim 39 wherein the tie-layer
comprises an adhesive composition selected from the group
consisting of vinyl/acrylic compositions, blends of polyolefin
resins comprising ethylene vinyl acetate copolymers, blends of
polyolefin resins comprising ethylene methyl acrylate copolymers,
modified ethylene vinyl acetate resins, ethylene vinyl acetate
resins, ethylene methyl acrylate resins, and polyester-based
polyurethanes.
42. A blister package according to claim 39 wherein the seal
between the heat-seal layer and the blister component is peelable
such that the blister package can be opened by peeling the lidding
component from the blister component.
43. A blister package according to claim 41 wherein the heat-seal
layer comprises a heat-sealable sealant selected from the group
consisting of poly(vinylidene chloride), vinyl/acrylic
compositions, blends of polyolefin resins comprising ethylene vinyl
acetate copolymers, and blends of polyolefin resins comprising
ethylene methyl acrylate copolymers.
44. A blister package according to claim 39 wherein the second
barrier layer is frangible.
45. A blister package according to claim 44 wherein the adhesive
tie layer is a peelable layer such that the combined flash spun
plexifilamentary sheet and adhesive tie layer can be peeled away
from the second barrier layer and a material packaged in the
blister package can be removed from the package after said peeling
by pushing the packaged material through the frangible barrier
layer.
46. A blister package according to claim 45 wherein the adhesive
tie layer comprises an adhesive composition selected from the group
consisting of vinyl/acrylic compositions, blends of polyolefin
resins comprising ethylene vinyl acetate copolymers, and blends of
polyolefin resins comprising ethylene methyl acrylate
copolymers.
47. A blister package according to claim 45 wherein the second
barrier layer comprises a metalized polymeric film that is
metalized on one side thereof, and wherein the metalized side of
the second barrier layer is adjacent the adhesive tie layer.
48. A blister package according to claim 45 wherein the second
barrier layer comprises a polymeric film that is coated on one side
thereof with a ceramic material, and wherein the coated side of the
second barrier layer is adjacent the adhesive tie layer.
49. A blister package according to claim 47 wherein the metalized
polymeric film comprises a metalized biaxially-oriented film.
50. A blister package according to claim 38 wherein the second
barrier layer is heat sealable and is adhered to the flash spun
plexifilamentary sheet, the inner surface of the lidding component
comprises the heat-sealable barrier layer, and the lidding and
blister components are heat sealed together to form a seal
therebetween.
51. A blister package according to claim 50 wherein seal is a
peelable seal such that the blister package can be opened by
peeling the lidding component from the blister component.
52. A blister package according to claim 50 wherein the seal is a
non-peelable seal and the blister package further comprises at
least one notch located internal to the package or on an external
edge of the package.
53. A blister package according to claim 51 or 52 wherein the
heat-sealable barrier layer comprises poly(vinylidene
chloride).
54. A blister package according to claim 38 or 39 wherein the flash
spun plexifilamentary sheet is formed from at least one polymer
selected from the group consisting of polyethylene, polypropylene,
and poly(ethylene terephthalate).
55. A blister package according to claim 54 wherein the second
barrier layer comprises a sheet layer selected from the group
consisting of polyester films and polyester films having a coating
of aluminum metal deposited on at least one side thereof.
56. A blister package according to claim 55 wherein the second
barrier layer comprises a polyester film comprising poly(ethylene
terephthalate).
57. A blister package according to claim 1 wherein the nonwoven
layer has a Spencer Puncture measured according to ASTM D3420 with
a {fraction (9/16)} inch diameter probe and a pendulum capacity of
5.4 Joules of at least 0.98 Joules, a tensile strength measured
according to ASTM D5035 in both the machine direction and
cross-direction of at least 35 N/cm, an elongation measured
according to ASTM D5035 in both the machine direction and
cross-direction of at least 15%, and an Elmendorf Tear measured
according to ASTM D1424 in both the machine direction and the
cross-direction of at least 0.33 N.
58. A blister package according to claim 57 wherein the nonwoven
layer has a Spencer Puncture of at least 1.97 Joules, a tensile
strength in both the machine and cross-direction of at least 43.8
N/cm, an elongation in both the machine direction and
cross-direction of at least 20%, and an Elmendorf Tear of at least
0.89 N.
59. A blister package according to claim 57 or 58 wherein the
nonwoven layer is a bicomponent spunbond web.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to improved child-resistant
blister packaging. More particularly, this invention relates to
blister packaging that includes a lidding component that comprises
at least one nonwoven layer selected from the group consisting of
melt-spun continuous filament nonwoven sheets and flash spun
plexifilamentary sheets.
[0002] Blister packages are known in the art, for example as
packaging for pharmaceuticals and other materials. Blister packages
include a blister component having at least one cavity formed
therein into which the medicine or other packaged material is
placed prior to being sealed to a lidding or top web component.
Blister components known in the art include soft-tempered aluminum
foils, hard-tempered aluminum foils, multi-layer cold formable
foils, and thermoformed films. Lidding components known in the art
include films, and combinations of films, paper, and/or foil. The
lidding component generally has a heat-seal layer applied to one
side thereof which is used to heat seal the lidding component to
the blister component during the manufacture of the blister
package. When used for packaging pharmaceuticals and other
materials that are oxygen- and/or moisture-sensitive, the blister
package should have sufficient barrier properties to ensure a
reasonable shelf-life for the packaged materials. When used for
packaging pharmaceuticals or other materials that may be harmful to
children, a blister package should also be child-resistant so that
a child cannot open the package, bite through it, or otherwise
damage the packaging in a way that exposes the packaged
pharmaceutical or other packaged material. At the same time, it is
generally desirable that an adult can open the blister package
without undue effort.
[0003] Examples of blister packages known in the art include
peel-open, tear-open, push-through, and peel off-push through
packages. In a peel-open package, the lidding component is peeled
away from the blister component to reveal the packaged material. In
a tear-open package, the lidding and blister components contain a
notch or perforation that extends from an edge of the package in
the direction of the cavity. The notch can be made in an external
edge of a package, or, for packages comprising multiple blisters
separated by perforations, the notch is preferably contained
internal to the package such that when an individual blister is
separated at the perforations from the rest of the blisters in the
package, the notch in the separated blister is on an exposed edge
thereof. The package is then torn at the notch and the tear is
propagated until the contents of the package are capable of being
removed. In a push-through package, the packaged material is pushed
through the lidding component by applying finger pressure to the
exterior of the blister cavity. In a peel off-push through package,
the lidding component is a multi-layer laminate that generally
includes an outer paper layer bonded by an intermediate adhesive
layer to a film layer (e.g. polyester film), with the film layer
also being bonded by a peelable adhesive layer to a foil layer on
the side of the film opposite that which is bonded to the paper
layer. The foil layer generally has a heat-seal layer coated or
otherwise applied to the side of the foil opposite the film which
provides a non-peelable seal when heat-sealed to the blister
component. To open the package, the lidding is peeled between the
film and the foil layers, leaving the foil layer attached to the
blister component. After peeling off the combined paper and film
lidding layers, the packaged material is pushed through the lidding
layer(s) that remains attached to the blister component. Generally
the peelable adhesive layer remains adhered to the film layer
during peeling such that only the foil layer remains attached to
the blister component after peeling. An example of a peel off-push
through blister package is described in Brunda, U.S. Pat. No.
3,899,080. The blister package comprises a peelable outer layer,
for example film, cardboard, or paper that is adhered by a peelable
adhesive to a rupturable layer such as paper, selected plastics, or
metal foil.
[0004] One challenge in the manufacture of blister packaging is to
make a package that is child resistant that can also be opened by
an adult without undue difficulty. Certain child-resistant blister
packages known in the art include peel-open packages that comprise
a laminated paper-film lidding component adhered to a plastic
blister component by a peelable sealant. Further child-resistance
is obtained using peel off-push through packages, which comprise
the multi-layer lidding material described above. One disadvantage
of current peel off-push through packages is that paper-film-foil
laminates used in the lidding do not generally peel cleanly in one
piece and often tear at the perforation, making it difficult to
initiate a new peel. Some paper-film laminates and paper-film-foil
laminates also have poor puncture resistance and can be chewed
through by a child. Another disadvantage of using paper-film
laminates or paper-film-foil laminates in the lidding component is
that it is not unusual to have problems with moisture being sealed
in the blister when moisture that is retained in the paper forms
steam at the high temperatures used in the
heat-sealing-process.
[0005] Poore, British patent GB 2151581 describes push-through
strip packaging described as child-resistant that includes first
and second planar sheet materials with the packaged elements
enclosed therebetween. Neither of the planar sheet materials
contains pre-formed blisters, but rather the necessary
accommodation of the packaged elements is afforded by stretching of
the material of each sheet as they are sealed together. The first
sheet is a laminate of a paper or a foil with a tear-resistant
biaxially oriented plastic material together with an adhesive layer
that is preferably a heat-sealable adhesive layer. The second sheet
preferably has a push through force of at least about 70 N and
comprises a laminate of paper or metal foil and a layer of plastic
or other material that can provide adhesive properties, preferably
a heat-sealable adhesive. The package permits the removal of
individual elements through the second sheet by application of
finger pressure.
[0006] Gerber published European Patent Application 0959020
describes a peel off-push through type blister package that
includes a cover sheet containing a metal foil-free push-through
penetrable plastic layer, a peelable release adhesive, and a
non-penetrable cover layer. The cover layer is peeled off the
release adhesive in a first step and the packaged material is
pushed through the metal foil-free penetrable plastic layer.
Suitable cover layers include mono-films, film laminates containing
thermoplastics, papers or layered materials of thermoplastic paper.
Suitable papers include cellulose papers, security papers, and
papers made of synthetic fibers.
[0007] Carter, U.S. Pat. No. 4,947,620 describes a blister pack
suitable for steam sterilization that includes a lidding material
of Tyvek.RTM. nonwoven material that is coated with an adhesive
only on the areas of the lidding that are bonded to the blister
component. The Tyvek.RTM. nonwoven material is breathable and
therefore such packaging is not suitable for packaging
pharmaceuticals and other materials that are oxygen or moisture
sensitive.
[0008] There remains a need for improved child-resistant blister
packaging that protects materials packaged therein from moisture
and/or oxygen that is also economical to manufacture.
BRIEF SUMMARY OF THE INVENTION
[0009] In a first embodiment, the present invention is directed to
a blister package comprising a blister component having an inner
surface and an outer surface and a multi-layer lidding component
having an inner surface and an outer surface, wherein selected
portions of the inner surfaces of the blister and lidding
components are adhered together to form at least one cavity
therebetween, the blister component comprising a first barrier
layer selected from the group consisting of polymeric films, coated
polymeric films, metal foils, and film-foil laminates, and the
lidding component comprising a second barrier layer and a nonwoven
layer comprising at least one melt-spun continuous filament
nonwoven sheet.
[0010] A second embodiment of the present invention is a blister
package comprising a blister component having an inner surface and
an outer surface and a multi-layer lidding component having an
inner surface and an outer surface, wherein selected portions of
the inner surfaces of the blister and lidding components are bonded
together to form at least one cavity therebetween, the blister
component comprising a first barrier layer selected from the group
consisting of polymeric films, coated polymeric films, metal foils,
and film-foil laminates, and the lidding component comprising a
flash spun plexifilamentary sheet and a second barrier layer
comprising a sheet layer selected from the group consisting of
polymeric films, coated polymeric films, and metalized polymeric
films.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic elevation view of a blister
package.
[0012] FIG. 2a is a schematic cross-sectional view of a lidding
material useful in blister packages of the present invention.
[0013] FIG. 2b is a schematic cross-sectional view of a second
embodiment of a lidding material useful in blister packages of the
present invention.
[0014] FIG. 3 is a schematic diagram of a process suitable for
preparing a blister package of the present invention.
[0015] FIG. 4 is a portion of the product made by the process of
FIG. 3, showing multiple blister packages.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The present invention relates to an improved child-resistant
blister package that comprises a multi-layer lidding component and
a blister component. The multi-layer lidding component includes at
least one barrier layer and at least one nonwoven layer selected
from the group consisting of melt-spun continuous filament nonwoven
sheets and flash spun plexifilamentary sheets. The blister packages
of the present invention include peel-open, tear-open, and peel
off-push through packages. The use of a melt-spun continuous
filament nonwoven sheet or flash spun plexifilamentary sheet in the
lidding results in a blister package that is difficult or
impossible to open by pushing the packaged item through the lidding
or by chewing through the lidding, thus improving the degree of
child resistance compared to packages known in the art. The term
"copolymer" as used herein includes random, block, alternating, and
graft copolymers prepared by polymerizing two or more comonomers
and thus includes dipolymers, terpolymers, etc.
[0017] The term "polyethylene" (PE) as used herein is intended to
encompass not only homopolymers of ethylene, but also copolymers
wherein at least 85% of the recurring units are ethylene units, and
includes "linear low density polyethylenes" (LLDPE) which are
linear ethylene/.alpha.-olefin copolymers having a density of less
than about 0.955 g/cm.sup.3, and "high density polyethylenes"
(HDPE), which are polyethylene homopolymers having a density of at
least about 0.94 g/cm.sup.3.
[0018] The term "polyester" as used herein is intended to embrace
polymers wherein at least 85% of the recurring units are
condensation products of dicarboxylic acids and dihydroxy alcohols
with linkages created by formation of ester units. Examples of
polyesters include poly(ethylene terephthalate) (PET), which is a
condensation product of ethylene glycol and terephthalic acid, and
poly(1,3-propylene terephthalate), which is a condensation product
of 1,3-propanediol and terephthalic acid.
[0019] The term "polyamide" as used herein is intended to embrace
polymers containing recurring amide (--CONH--) groups. One class of
polyamides is prepared by copolymerizing one or more dicarboxylic
acids with one or more diamines. Examples of polyamides suitable
for use in the present invention include poly(hexamethylene
adipamide) (nylon 6,6) and polycaprolactam (nylon 6).
[0020] The term "barrier layer" as used herein refers to a sheet
layer, including films and coatings that restrict the permeation of
oxygen and/or water vapor into a blister package that comprises the
sheet layer. Barrier layers suitable for use in the present
invention preferably have a moisture vapor transmission rate (MVTR)
of less than 6 g/m.sup.2/24 hr measured according to ASTM F1249
under the conditions of 38.degree. C. and 90% Relative Humidity
and/or an oxygen transmission rate of less than 28
cm.sup.3/m.sup.2/24 hr measured according to ASTM D3985 under the
conditions of 23.degree. C., 100% oxygen, and 100% Relative
Humidity.
[0021] The terms "nonwoven fabric", "nonwoven sheet", "nonwoven
layer", and "nonwoven web" as used herein refer to a structure of
individual fibers, filaments, or threads that are positioned in a
random manner to form a planar material without an identifiable
pattern, as opposed to a knitted or woven fabric. Examples of
nonwoven fabrics include meltblown webs, spunbond nonwoven webs,
flash spun webs, carded webs, spunlaced webs, and composite sheets
comprising more than one nonwoven web.
[0022] The term "machine direction" (MD) is used herein to refer to
the direction in which a nonwoven web is produced (e.g. the
direction of travel of the supporting surface upon which the fibers
are laid down during formation of the nonwoven web). The term
"cross direction" (XD) refers to the direction generally
perpendicular to the machine direction in the plane of the web.
[0023] The term "spunbond fibers" as used herein means fibers that
are melt-spun by extruding molten thermoplastic polymer material as
fibers from a plurality of fine, usually circular, capillaries of a
spinneret with the diameter of the extruded fibers then being
rapidly reduced by drawing and then quenching the fibers.
[0024] The term "meltblown fibers" as used herein, means fibers
that are melt-spun by meltblowing, which comprises extruding a
melt-processable polymer through a plurality of capillaries as
molten streams into a high velocity gas (e.g. air) stream.
[0025] The term "spunbond-meltblown-spunbond nonwoven fabric"
("SMS") as used herein refers to a multi-layer composite sheet
comprising a web of meltblown fibers sandwiched between and bonded
to two spunbond layers. Additional spunbond and/or meltblown layers
can be incorporated in the composite sheet, for example
spunbond-meltblown-meltblown-spunbond webs ("SMMS"), etc.
[0026] The term "multiple component fiber" as used herein refers to
a fiber that is composed of at least two distinct polymeric
components that have been spun together to form a single fiber. The
at least two polymeric components are arranged in distinct
substantially constantly positioned zones across the cross-section
of the multiple component fibers, the zones extending substantially
continuously along the length of the fibers.
[0027] The term "bicomponent fiber" is used herein to refer to a
multiple component fiber that is made from two distinct polymer
components, such as sheath-core fibers that comprises a first
polymeric component forming the sheath, and a second polymeric
component forming the core; and side-by-side fibers, in which the
first polymeric component forms at least one segment that is
adjacent at least one segment formed of the second polymeric
component, each segment being substantially continuous along the
length of the fiber with both polymeric components being exposed on
the fiber surface. Multiple component fibers are distinguished from
fibers that are extruded from a single homogeneous or heterogeneous
blend of polymeric materials. The term "multiple component nonwoven
web" as used herein refers to a nonwoven web comprising multiple
component fibers. The term "bicomponent web" as used herein refers
to a nonwoven web comprising bicomponent fibers. A multiple
component web can comprise single component and/or polymer blend
fibers in addition to multiple component fibers.
[0028] The term "plexifilamentary" as used herein, means a
three-dimensional integral network or web of a multitude of thin,
ribbon-like, film-fibril elements of random length and with a mean
film thickness of less than about 4 microns and a median fibril
width of less than about 25 microns. In plexifilamentary
structures, the film-fibril elements are generally coextensively
aligned with the longitudinal axis of the structure and they
intermittently unite and separate at irregular intervals in various
places throughout the length, width and thickness of the structure
to form a continuous three-dimensional network. A nonwoven web of
plexifilamentary film-fibril elements is referred to herein as a
"flash spun plexifilamentary sheet". Conventional flash spinning
processes for forming web layers of plexifilamentary film-fibril
strand material are disclosed in U.S. Pat. No. 3,081,519 (Blades et
al.), U.S. Pat. No. 3,169,899 (Steuber), U.S. Pat. No. 3,227,784
(Blades et al.), U.S. Pat. No. 3,851,023 (Brethauer et al.), the
contents of which are hereby incorporated by reference.
[0029] As used herein, the term "film" includes layers that are
extruded directly onto one of the other layers in the lidding or
blister components, as well as films that are formed in a separate
film-forming step and then laminated to one or more other
layers.
[0030] The term "full-surface bonded nonwoven fabric" as used
herein refers to a nonwoven fabric that has been bonded by applying
heat and pressure to the nonwoven fabric between two substantially
smooth bonding surfaces. A full-surface bonded nonwoven fabric is
bonded over substantially 100% of its outer surfaces by
fiber-to-fiber bonds. The use of smooth bonding surfaces results in
each side of the full-surface bonded nonwoven fabric being
substantially uniformly bonded. Full surface bonded nonwoven
fabrics are described in co-pending U.S. Patent Application No.
60/529,997 (DuPont Docket no. TK-3820), filed on even date herewith
and incorporated herein by reference in its entirety.
[0031] FIG. 1 illustrates a schematic elevation view of a blister
package according to the present invention. Lidding component 1 is
heat-sealed to a blister component comprising a plurality of
cavities 2. The lidding and blister components are heat-sealed in
the shoulder areas 3 that separate the individual cavities. The
shoulder areas generally include perforations (not shown) between
the individual blisters or groups of individual blisters.
[0032] The blister component is formed from a forming web that
comprises at least one barrier layer, for example a polymeric film,
coated polymeric film, or metal foil. Forming webs suitable for
forming the blister component are known in the art. For example,
the blister component can be prepared by thermoforming cavities
into a barrier film. Alternately, the blister component can be
formed from a soft-tempered or a hard-tempered foil such as an
aluminum foil layer. Films and foils suitable for forming the
blister component generally have a thickness between about 5.0 mils
(0.125 mm) and 15 mils (0.38 mm) for child-resistant packaging. For
example, a typical film thickness is about 10 mils (0.25 mm). The
blister component can be formed from a multi-layer sheet structure,
for example a multi-layer film or a film-foil laminate.
[0033] FIG. 2a is a cross-sectional view of an embodiment of a
lidding component suitable for use in peel-open, tear-open, and
peel off-push through blister packages of the present invention.
Nonwoven layer 5, which comprises at least one melt-spun continuous
filament sheet or flash spun plexifilamentary sheet, is bonded to
barrier layer 7 by intervening adhesive tie layer 6. Heat-seal
layer 8 is adhered to the barrier layer on the side of the barrier
layer opposite the tie layer. A blister package is formed by
heat-sealing the lidding component to the blister component with
heat-seal layer 8 facing the blister component such that nonwoven
layer 5 forms one of the outer surfaces of the blister package. Tie
layer 6 can form a peelable seal (e.g. in a peel off-push through
package) or a non-peelable seal (e.g. in a peel-open or tear-open
package) between the nonwoven layer and the barrier layer,
depending on the desired method for opening the blister package. A
seal or bond is considered non-peelable if the layers bonded by the
non-peelable seal are not readily opened by an adult by
hand-peeling. Generally a seal having a peel strength between about
3 to 4 lb/in is preferred for a peelable seal. Peel strengths less
than about 3 lb/in are generally peeled too easily to be useful in
child-resistant packages. Seals having a peel strength greater than
about 4 lb/inch are generally considered to be non-peelable or
permanent seals. Peel strength can be measured according to ASTM F
88-0, which is hereby incorporated by reference, using the
unsupported method of clamping the sample described therein.
Similarly, heat-seal layer 8 can form a peelable seal (e.g. in a
peel-open package) or a non-peelable seal (e.g. in a peel off-push
through or tear-open package) between the barrier layer and the
blister component. Examples of lidding constructions according to
FIG. 2a include: (a) melt-spun continuous filament nonwoven
sheet/adhesive tie layer/metal foil/heat-seal layer, (b) melt-spun
continuous filament nonwoven sheet/adhesive tie layer/barrier film
(metalized or unmetalized, coated or uncoated)/heat-seal layer,
and
[0034] (c) flash spun plexifilamentary sheet/adhesive tie
layer/barrier film (metalized or unmetalized, coated or
uncoated)/heat-seal layer. The barrier film can be a film that is
laminated to the nonwoven sheet or can be a layer that is
co-extruded with the adhesive tie layer onto the nonwoven
sheet.
[0035] Barrier layers suitable for use in the lidding component
shown in FIG. 2a include foil sheets such as aluminum foil and
laminated structures comprising a foil layer such as film-foil
laminates, as well as mono-layer, multi-layer, and coated polymeric
films, and metalized polymeric films.
[0036] Examples of other materials useful as either the barrier
layers suitable for use in the lidding component, or as the blister
component include poly(vinyl chloride) (PVC) used as a mono-layer
film, PVC film coated with poly(vinylidene chloride) (PVdC), PVC
film laminated with poly(chlorotrifluoroethylene) (PCTFE) film such
as Aclar.RTM. PCTFE film available from Honeywell, Inc. (Morris
Township, N.J.), cyclo-olefin-copolymer (COC) used as part of a
laminated or co-extruded structure, cold-formable foil such as
PVC/aluminum/nylon laminated structures, mono-layer aluminum foil,
polypropylene (PP) used as a mono-layer film, poly(ethylene
terephthalate) (PET) used as a mono-layer film, and poly(ethylene
terephthalate) copolymers that have been modified with
1,4-cyclohexanedimethanol, available from Eastman Chemicals
(Kingsport, Tenn.) as PETG copolymers, used as a mono-layer
film.
[0037] In one embodiment the barrier layer comprises a polymeric
film comprising a polymeric coating. For example, the barrier layer
can comprise a PVdC-coated polyester film such as PVdC-coated
Mylar.RTM. polyester films (e.g. M30 and M34 films, available from
DuPont Teijin Films). In another embodiment, the barrier layer
comprises a polymeric film that has been coated with a ceramic
material. Ceramic materials suitable for coating polymeric films
include oxides, nitrides, or carbides of silicon, aluminum,
magnesium, chromium, lanthanum, titanium, boron, zirconium, or
mixtures thereof. Methods for depositing ceramic coatings onto a
substrate are known in the art, such as by deposition from the
vapor or gaseous phase under vacuum onto a film layer in
thicknesses of between about 5 to 500 nm. Suitable ceramic-coated
films include films made of a thermoplastic material, such as
polyolefin films having a thickness of 23 to 100 .mu.m or polyester
films having a thickness of 12 to 80 .mu.m, that have been coated
with at least one 5 to 500 nm thick layer of SiO.sub.x, where x is
a number ranging from 1.1 to 2, or with Al.sub.yO.sub.z, where the
ratio y/z is a number ranging from 0.2 to 1.5. Alternately, the
barrier layer can comprise a metalized film prepared using
processes known in the art such as vacuum deposition or sputter
coating. In one embodiment, the barrier layer is a metalized
polyester film, for example a poly(ethylene terephthalate) film,
that has a layer of aluminum metal coated thereon; preferably the
metal layer is between about 10 Angstroms to 1000 Angstroms thick
and the film is preferably at least 12 microns thick. Metalized
polyester films are known in the art and include aluminum-coated
polyester films such as Mylar.RTM. MC2 aluminum-coated polyester
film (available from DuPont Teijin Films). When the barrier layer
of the lidding component comprises a ceramic-coated or a metalized
polymeric film, the film can be ceramic-coated or metalized on one
or both sides. The polymeric film is preferably ceramic-coated or
metalized on one side thereof and the lidding is preferably
constructed such that the metalized or ceramic-coated side of the
film contacts adhesive tie layer 6 to avoid flaking off of the
metalized or ceramic layer onto the packaged material when the
package is opened. Metalized and ceramic-coated films generally
have better barrier properties than unmetalized and uncoated films
and therefore are preferred when higher barrier is required than
can be achieved with an un-metalized or uncoated film.
[0038] FIG. 2b is a cross-sectional view of a second embodiment of
a lidding component suitable for use in peel-open and tear-open
blister packages of the present invention. The lidding component
includes nonwoven layer 5' and heat-seal layer 8'. In this
embodiment, the heat-seal layer is selected such that it is a
barrier layer as well as being heat-sealable, thus eliminating the
need for separate barrier and heat-seal layers. The nonwoven layer
comprises at least one melt-spun continuous filament nonwoven sheet
or at least one flash spun plexifilamentary sheet. When the
heat-sealable barrier layer is applied as a coating on the nonwoven
layer, it completely coats the nonwoven layer to provide the
desired barrier properties in the blister package. For example,
PVdC at a basis weight ranging from 5 g/m.sup.2 to 120 g/m.sup.2
coated on a nonwoven layer provides sufficient barrier properties
as well as functioning as a heat-seal layer. Depending on the
selection of the heat-sealable barrier layer and the blister
component, the heat seal can be peelable or non-peelable. When it
is desired to form a peel-open package, the heat-sealable barrier
layer and the blister component are selected such that the heat
seal is peelable. When it is desired to form a tear-open package,
the heat seal is preferably non-peelable. In one embodiment of the
present invention according to FIG. 2b, a tear-open package is
formed using a PVdC blister component and a PVdC heat sealable
barrier layer (heat seal is non-peelable). In another embodiment of
the present invention according to FIG. 2b, a peel-open package is
formed using a PVC blister component and a PVdC heat-sealable
barrier layer, where the PVdC formulation is selected to form a
peelable seal with the PVC blister. The lidding shown in FIG. 2b
optionally includes a non-peelable tie layer (not shown) between
the nonwoven layer and heat-seal/barrier layer. For example the tie
layer can be a polyester-based polyurethane composition such as
Adcote.RTM. polyurethane adhesives available from Rohm & Haas
(Philadelphia, Pa.).
[0039] Melt-spun continuous filament nonwoven sheets suitable for
use in the nonwoven layer in the lidding component include spunbond
nonwoven webs and composite nonwoven fabrics that comprise at least
one spunbond nonwoven web. Spunbond webs suitable for use in the
lidding component of the blister package of the present invention
can be prepared using spunbonding methods known in the art.
Alternately, the melt-spun continuous filament nonwoven sheet can
be formed from previously collected continuous filaments that are
laid down on a collecting surface, for example as in the process
described in Davies et al. U.S. Pat. No. 3,595,731. Polymers
suitable for forming the melt-spun continuous filament nonwoven
sheet include polyesters such as poly(ethylene terephthalate) and
poly(1,3-propylene terephthalate), polyamides such as nylon 6,6 and
nylon 6, polyolefins such as polyethylene and polypropylene, and
copolymers thereof.
[0040] The melt-spun continuous filaments of the continuous
filament nonwoven sheet can be spun from a single polymer or from a
homogeneous or heterogeneous blend of two or more polymers.
Alternately, the melt-spun continuous filament nonwoven sheet can
comprise a multiple component spunbond nonwoven web. Multiple
component spunbond webs preferably comprise a polymeric component
that has a melting point that is lower than the melting point(s) of
the other polymeric component(s) to facilitate thermal bonding of
the web. Examples of suitable multiple component fiber
cross-sections include bicomponent fibers such as those having
side-by-side or sheath-core cross-sections. In one embodiment of
the present invention, the melt-spun continuous filament nonwoven
sheet comprises multiple component sheath-core spunbond fibers
having a substantially concentric cross-section wherein the melting
point of the sheath component is at least 10.degree. C., preferably
at least 20.degree. C., less than the melting point of the core
component. Examples of suitable sheath/core polymer combinations
are polyethylene/polyester such as fibers comprising a linear low
density polyethylene sheath with a poly(ethylene terephthalate)
core or a sheath comprising a blend of LLDPE and HDPE with a PET
core. In one embodiment, the melt-spun continuous filaments
comprise a polyester copolymer sheath and a polyester core. For
example, the sheath can comprise a poly(ethylene terephthalate)
copolymer and the core can comprise poly(ethylene terephthalate).
Poly(ethylene terephthalate) copolymers suitable for use as the
sheath component include amorphous and semi-crystalline
poly(ethylene terephthalate) copolymers. For example, poly(ethylene
terephthalate) copolymers in which between about 5 and 30 mole
percent based on the diacid component is formed from di-methyl
isophthalic acid, as well as poly(ethylene terephthalate)
copolymers in which between about 5 and 60 mole percent based on
the glycol component is formed from 1,4-cyclohexanedimethanol are
suitable for use as the lowest-melting component in the multiple
component fibers. Poly(ethylene terephthalate) copolymers that have
been modified with 1,4-cyclohexanedimethanol are available from
Eastman Chemicals (Kingsport, Tenn.) as PETG copolymers.
Poly(ethylene terephthalate) copolymers that have been modified
with di-methyl isophthalic acid are available from E.I. du Pont de
Nemours and Company (Wilmington, Del.) as Crystar.RTM. polyester
copolymers.
[0041] Composite nonwoven fabrics comprising a spunbond nonwoven
web suitable for use in the lidding component include
spunbond-meltblown (SM) composite nonwoven fabrics, SMS composite
nonwoven fabrics, and composite nonwoven fabrics that include other
combinations of spunbond and/or meltblown nonwoven webs such as
SMMS composite webs, etc. The meltblown web(s) used to prepare the
composite nonwoven fabrics can be single component or multiple
component meltblown web(s) and can be prepared using methods known
in the art.
[0042] The nonwoven layer used in the lidding component can
comprise a flash spun nonwoven sheet. Polymers suitable for forming
flash spun plexifilamentary sheets useful in the lidding component
of the blister package of the present invention include
polyethylene, polypropylene, and poly(ethylene terephthalate). One
such flash spun plexifilamentary sheet is Tyvek.RTM. flash spun
high density polyethylene, available from E.I. du Pont de Nemours
& Company (Wilmington, Del.).
[0043] A particularly suitable lidding component can be obtained by
smooth-surface thermal bonding of a nonwoven web can be achieved by
heating the web between two smooth bonding surfaces to a
temperature sufficient to melt or soften the surfaces of the fibers
on one or both sides of the nonwoven web such that fiber-to-fiber
thermal fusion bonds are formed at the fiber cross-over points on
one or both surfaces of the nonwoven web, as disclosed in U.S. Ser.
No. 60/529,997 (DuPont Docket no. TK-3820), filed on even date
herewith and incorporated herein by reference in its entirety.
[0044] Thermal calendering processes using a variety of roll
configurations are known in the art. The nonwoven layer can be
calender bonded such that one side of the nonwoven layer is
thermally bonded, with the thermally bonded side forming one of the
outer surfaces of the final blister package. Alternately the
nonwoven layer can be calendered such that both sides of the
nonwoven layer are thermally bonded. Examples of other calendering
processes suitable for bonding the nonwoven layer include those
disclosed in David, U.S. Pat. No. 3,532,589, Janis, U.S. Pat. No.
5,972,147, and Lim et al., U.S. Pat. No. 5,308,691, which are each
incorporated herein by reference.
[0045] In one embodiment, the nonwoven layer comprises a
full-surface bonded melt-spun multiple component continuous
filament nonwoven fabric or full-surface bonded flash spun
plexifilamentary sheet that has been thermally bonded on both sides
in a smooth-calendering process. Full-surface bonded melt-spun
multiple component continuous filament nonwoven fabrics have an
improved combination of tensile and tear strength for a given
fabric thickness compared to comparable smooth-calendered single
component melt-spun nonwoven fabrics. Suitable full-surface bonded
melt-spun multiple component continuous filament nonwoven fabrics
include full-surface bonded bicomponent spunbond webs such as a
spunbond web comprising sheath/core fibers, wherein the melting
point of the sheath is at least 10.degree. C. less than the melting
point of the core, that has been smooth-calendered and bonded on
both sides. Suitable sheath components include polyester
copolymers, poly(1,4-butylene terephthalate) (4GT), and
poly(1,3-propylene terephthalate) (3GT), and polyamides such as
polycaprolactam (nylon 6). Suitable core components include
poly(ethylene terephthalate) and poly(hexamethylene adipamide)
(nylon 6,6). For example, the full-surface bonded bicomponent
spunbond web can comprise bicomponent fibers having a polyester
copolymer sheath and a poly(ethylene terephthalate) core.
[0046] The nonwoven layer preferably has a Spencer Puncture
(measured according to ASTM D3420, modified for {fraction (9/16)}
in. diameter probe) of at least 0.98 Joules, preferably at least
1.18 Joules, and more preferably at least 1.97 Joules; a tensile
strength (measured according to ASTM D5035) in both the machine
direction and cross-direction of at least 20 lb/in (35 N/cm),
preferably at least 22 lb/in (38.5 N/cm), and more preferably at
least 25 lb/in (43.8 N/cm); an elongation in both the machine
direction and cross-direction of at least 15%, preferably at least
18%, and more preferably at least 20%; and an Elmendorf Tear
(measured according to ASTM D1424) in both the machine direction
and the cross-direction of at least 0.075 lb (0.33 N), preferably
at least 0.10 lb (0.45 N), and more preferably at least 0.20 lb
(0.89 N).
[0047] In one embodiment of the present invention the heat-seal
layer comprises a peelable sealant, thus providing a peel-open
blister package. Whether or not a particular heat-seal layer forms
a peelable seal may depend on the nature of the layers to which it
is sealed (e.g. the blister component and barrier layer for the
embodiment shown in FIG. 2a or the blister component and the
nonwoven layer for embodiments shown in FIG. 2b). In a peel-open
configuration, the package is opened by peeling the multi-layer
lidding component away from the blister component, with the peeling
occurring between the heat-seal layer and the blister component.
Peelable sealants suitable for use in the heat-seal layer of the
packages of the present invention include poly(vinylidene
chloride), or solvent-based sealants such as modified vinyl/acrylic
sealants available from Watson Rhenania (Pittsburgh, Pa.) such as
JVHS-157-LT1 sealant, as well as extrudable sealants, for example
blends of polyolefin resins comprising primarily ethylene vinyl
acetate or ethylene methyl acrylate copolymers, such as Appeel.RTM.
resins, available from E.I. du Pont de Nemours and Company
(Wilmington, Del.). The heat-seal layer can be applied to the
barrier layer of the lidding component using methods known in the
art including but not limited to roll coating, gravure coating,
spray coating, and extrusion coating. In a peel-open package, a
non-peelable adhesive tie layer is preferably used to join the
nonwoven layer to the barrier layer so that the nonwoven and
barrier layers are strongly bonded together, allowing the
multi-layer lidding to be cleanly pulled away from the blister
component without delamination occurring between the nonwoven and
barrier layers. Non-peelable adhesive tie layers suitable for use
in lidding used in a peel-open package of the present invention
include solvent-based two-component dry-bond adhesive compositions
such as polyester-based polyurethane adhesives, for example
Adcote.RTM. polyurethane-based adhesives available from Rohm &
Haas (Philadelphia, Pa.). In a dry-bond adhesive process, the
adhesive is applied to either the barrier layer or the nonwoven
layer or both, and the two layers are bonded together while the
adhesive is "dry" or substantially free of solvent. If the starting
adhesive composition comprises a solvent, it is dried prior to
laminating the nonwoven layer to the barrier layer. Other adhesive
compositions which provide a non-peelable tie layer include
extrudable resins such as modified ethylene vinyl acetate, ethylene
vinyl acetate, and ethylene methyl acrylate based resins, for
example Bynel.RTM. and Nucrel.RTM. modified ethylene vinyl acetate
and modified ethylene methyl acrylate resins, available from E.I.
du Pont de Nemours and Company (Wilmington, Del.).
[0048] In another embodiment of a blister package of the present
invention, the blister package is a peel off-push through package
wherein the outer nonwoven layer is adhered to a frangible barrier
layer by a peelable tie layer, and is peeled from the package to
reveal the frangible barrier layer through which the packaged
material is pushed. A layer is considered to be frangible if a
packaged material can be removed by rupturing the layer by applying
pressure to the exterior of the blister cavity. Peeling may occur
between the nonwoven layer and the adhesive tie layer or between
the adhesive tie layer and the barrier layer. The adhesive tie
layer is preferably selected such that it remains adhered to the
nonwoven layer and peels cleanly away from the barrier layer when
the package is opened without tearing or otherwise rupturing the
barrier layer. That is, the adhesive tie layer preferably has a
high adherence to the nonwoven layer and a relatively lower
adherence to the frangible barrier layer. If peeling occurs between
the nonwoven layer and the adhesive tie layer, the adhesive tie
layer should also be a frangible layer. For example, in a peel
off-push through package comprising a lidding component according
to FIG. 2a, the adhesive tie layer is a peelable layer such that
the nonwoven layer can be peeled away from the barrier layer of the
lidding component, and wherein the combined barrier layer/heat-seal
layer (for peeling between the adhesive tie layer and the barrier
layer) or combined adhesive tie layer/barrier layer/heat-seal layer
(for peeling between the nonwoven layer and tie layer) is
frangible. Examples of frangible barrier layers include metal foils
(e.g. aluminum foil), frangible polymeric films (e.g.
biaxially-oriented poly(chlorotrifluoroethylene) films), frangible
metalized polymeric films, and frangible ceramic-coated polymeric
films. The frangible layer(s) are selected such that once the
nonwoven layer (or combined nonwoven/adhesive tie layer) is peeled
away from the package, the pharmaceutical or other packaged
material can be pushed through the frangible layer(s). The adhesive
tie layer can be extruded or coated onto one or both of the
nonwoven layer (e.g. Tyvek.RTM. flash spun high density
polyethylene or melt-spun continuous filament polyester-based
spunbond nonwoven) or frangible barrier layer and the nonwoven and
barrier layer bonded together by the intermediate tie layer.
Examples of suitable peelable tie layers include modified
vinyl/acrylic compositions, such as JVHS-157-LT1 modified
vinyl/acrylic adhesive available from Watson Rhenania (Pittsburgh,
Pa.), or blends of polyolefin resins comprising primarily ethylene
vinyl acetate or ethylene methyl acrylate copolymers, such as
Appeel.RTM. polyolefin resins, available from E.I. du Pont de
Nemours and Company (Wilmington, Del.), and solvent-based modified
acrylic pressure sensitive adhesive, such as Adcote L74X105 from
Rohm & Haas (Philadelphia, Pa.). The heat-seal layer in a peel
off-push through package is selected such that it forms a
non-peelable seal between the blister component and the barrier
layer in the lidding. Examples of suitable permanent (non-peelable)
sealants include modified vinyl/acrylic compositions such as
JVHS-157-2, or a modified polyester sealant such as GNS01-014, both
available from Watson Rhenania (Pittsburgh, Pa.).
[0049] When a tear-open package is desired, the adhesive tie layer
and heat-seal layer of FIGS. 2a and 2b are selected such that
non-peelable bonds/seals are formed between the barrier layer and
the blister component and between the nonwoven layer and the
barrier layer. This allows the package to be torn cleanly at a
pre-formed notch in the package without peeling occurring between
the various layers in the multi-layer lidding component.
[0050] The blister package of the present invention can be
manufactured using methods known in the art. FIG. 3 illustrates a
process that is suitable for forming a blister package of the
present invention. The blister cavities 10 are generally
thermoformed into a forming web in-line just prior to filling the
cavities with the material 12 to be packaged. The lidding component
14 is unwound from roll 15 and brought into contact with the formed
and filled blister component such that the heat-seal layer of the
lidding component contacts the blister component. The lidding and
blister components are heat sealed, typically using a heated platen
16 with or without a pattern. Generally, some areas are not sealed
to provide a starting point for peeling off the lidding or selected
layers of the lidding prior to removing the product. If the lidding
component is not pre-printed, printing is generally done just
before heat sealing (not shown). After heat-sealing, the individual
blisters are generally perforated using methods known in the art
(not shown) so that they can be removed at point of use. If the
blister package is a tear-open package, notches are formed in the
individual blisters during the perforation step. The notches are
preferably contained internal to the package such that they are not
exposed until the individual blister is removed at point of use.
The notch can also be formed on one of the external edges of the
blister package, however forming the notches internal to the
package decreases the likelihood that a child will be able to tear
open the package. Individual blister packages 18, which can
comprise multiple blisters (as shown in FIG. 4) or a single
blister, are then cut from the continuous sheet of sealed blisters.
It is important that all materials maintain dimensional stability
through the blister package process due to the platen registry, the
print registry and the perforation registry.
[0051] The improved tear resistance provided by the continuous
filament or plexifilamentary nonwoven layer in the lidding
component of the packages of the present invention provides peel
off-push through and peel-open packages wherein the lidding or
nonwoven layer peels cleanly away from the package without tearing,
whereas packages known in the art that utilize paper-film-foil
laminates often do not provide a clean peel, thus making it
difficult for even an adult to open the package. The present
invention also reduces the number of processing steps required to
manufacture the lidding compared to the prior art by replacing
three layers (paper-adhesive-film) with a single nonwoven layer.
Although the tear resistance of the lidding component of the
packages of the present invention is improved compared to prior art
lidding materials, they can also be used in tear-open packages
wherein the tear is initiated by a pre-formed notch.
Test Methods
[0052] In the description above the following test methods are
employed to determine various reported characteristics and
properties. ASTM refers to the American Society for Testing and
Materials.
[0053] Basis Weight is a measure of the mass per unit area of a
fabric or sheet and is determined by ASTM D-3776, which is hereby
incorporated by reference, and is reported in g/m.sup.2.
[0054] Spencer Puncture is a measure of the ability of a substrate
to resist puncture by impact. Spencer puncture is measured for
nonwoven fabrics and nonwoven/foil laminates using a bullet-shaped
probe and is determined by ASTM D3420 (modified for {fraction
(9/16)} inch diameter probe) with a pendulum capacity of 5.4
Joules, which is hereby incorporated by reference. It is reported
in Joules. Spencer puncture was measured for nonwoven/film
laminates according to ASTM D3420 using a pointed probe (modified
for {fraction (9/16)} inch diameter probe) with a pendulum capacity
of 5.4 Joules, and is reported in units of Joules.
[0055] Tensile Strength is a measure of the force required to break
the material apart by pulling. For nonwoven fabrics and
nonwoven/foil laminates, tensile strength is determined according
to ASTM D5035, which is hereby incorporated by reference, and is
reported in units of lb/in or N/cm. For nonwoven/film laminates,
tensile strength was measured according to ASTM D882, which is
hereby incorporated by reference, and is reported in units of
psi.
[0056] Elongation is a measure of the extent a substrate with
stretch before it breaks and is determined by ASTM D5035, which is
hereby incorporated by reference. It is reported in %.
[0057] Elmendorf Tear is a measure of the force required to
propagate an initiated tear from a cut or a nick. Elmendorf Tear is
measured for nonwoven fabrics and nonwoven/foil laminates according
to ASTM D1424, which is hereby incorporated by reference, and is
reported in units of lb or N. Elmendorf Tear was measured for
nonwoven/film laminates according to ASTM 1922, and is reported in
units of g/mm.
[0058] Graves Tear is a measure of the force required to initiate a
tear and is measured according to ASTM D1004, which is hereby
incorporated by reference, and is reported in units of Newtons.
[0059] Moisture Vapor Transmission rate (MVTR) was measured for
Example 2 using ASTM F1249, which is hereby incorporated by
reference, under the conditions of 38.degree. C. and 100% Relative
Humidity, and is reported in units of g/m.sup.2/24 hr.
[0060] Oxygen Transmission Rate was measured for Example 2 using
ASTM D3985, which is hereby incorporated by reference, at
23.degree. C., 50% RH, and 100% oxygen, and is reported in units of
cc/m.sup.2/24 hr.
EXAMPLE 1
[0061] This example demonstrates preparation of a blister package
comprising a lidding component according to FIG. 2a, wherein the
nonwoven layer was a smooth-calendered full-surface bonded spunbond
nonwoven web and the barrier layer in the lidding was a metal
foil.
[0062] A spunbond bicomponent nonwoven web was prepared in which
the fibers were continuous core/sheath fibers having a
poly(ethylene terephthalate) (PET) core component and a
co-polyester sheath component composed of 17 mole percent modified
di-methyl isophthalate PET copolymer.
[0063] The thermally calendered bicomponent spunbond web was then
laminated to a 0.93 mil (0.024 mm) thick soft-tempered aluminum
foil obtained from Alcoa (Pittsburgh, Pa.) using Adcote 503 A/Cat F
solvent-based poly(ethylene terephthalate)-based polyurethane
permanent adhesive tie layer obtained from Rohm & Haas
(Philadelphia, Pa.). An Inta-Roto dry-bond coater/laminator (Model
`The Delaware`) was used to perform the lamination. The Adcote
503A/Cat F was mixed at a ratio of 62 percent by weight 503A, 3.5
percent by weight CatF, and 34.5 percent by weight methyl ethyl
ketone and the adhesive was applied using a reverse gravure coating
process. The bicomponent spunbond web was unwound from a primary
unwind and the adhesive was applied to the bicomponent spunbond web
using a reverse rotating gravure roll. Alternately, the adhesive
can be applied to the barrier layer. The gravure roll was engraved
with a 35 line per inch (13.8 line per cm) tri-helical pattern,
where a continuous triangular channel in the helical pattern
circumvents the gravure roll. The machine speed was 65 ft/min (19.8
m/min). Typical line speeds used in a reverse gravure coating
process are usually between about 15 m/min to 305 m/min. The
adhesive was applied at a dry coating weight of about 8 g/m.sup.2.
An adhesive tie layer dry coating weight between about 3 g/m.sup.2
and 10 g/m.sup.2 is generally used, with a dry coating weight
between about 4 g/m.sup.2 and 8 g/m.sup.2 generally being
preferred. A hot air impingement dryer was used to dry the coated
spunbond web to remove the solvent present in the tie layer
adhesive. Air heated to a temperature of 74.degree. C. was forced
through a slotted nozzle assembly onto the adhesive-coated surface
of the spunbond web evaporate the solvent.
[0064] After drying, the adhesive-coated spunbond nonwoven web
layer was laminated to the foil layer which was unwound from a roll
and contacted with the adhesive-coated side of the spunbond web in
a nip formed by two cylindrical calender rolls. One of the rolls
was a rubber-covered roll and the second roll was a steel roll
heated to 82.degree. C. by internal water heating. The nonwoven web
contacted the heated steel roll in the nip and the aluminum foil
contacted the rubber-surfaced roll. The laminated substrate was
then rewound on the rewinder.
[0065] A solvent-based peelable heat seal layer was then applied to
the aluminum foil side of the above-described spunbond
nonwoven/aluminum foil laminate using the reverse gravure coating
process described above. The peelable heat seal composition used
was a vinyl/acrylic solvent-based sealant (JVHS-157-LT1, supplied
byWatson-Rhenania, Pittsburgh, Pa.). The heat-seal coating was
applied at 5.2 g/m.sup.2 to the nonwoven/foil laminate. Generally,
heat seal coatings applied at a dry coating weight of between about
4.8 to 5.6 g/m.sup.2 are preferred. After applying the sealant, the
coated material was dried using the same hot air impingement dryer
described above and an air temperature of 275.degree. F.
(135.degree. C.) to remove the ethyl acetate solvent. After drying
the laminate was rewound on the rewinder. The multi-layer laminate
can be used directly as a lidding component to prepare a blister
package or further processed by printing on the nonwoven surface of
the laminate prior to forming a blister package. Properties of the
lidding component are compared to a conventional paper-film-foil
laminate that is used in the art as lidding in blister packages
(CR-417, available from Hueck Foils (Wall, N.J.) in Table I below.
The results demonstrate the significant improvement in Spencer
Puncture of the lidding of the present invention compared to the
prior art lidding material. The puncture resistance of the laminate
prepared in Example 1 was more than three times greater than the
conventional lidding material. Blister packages prepared according
to the present invention are expected to be much more difficult for
a child to chew through than conventional blister packages.
[0066] Blister packages were prepared according to the process
shown in FIG. 3 using a Klockner Medipak CP-2 form-fill-seal
blister packaging machine. The forming web used to form the blister
component was 10 mil (0.254 mm) Pentapharm M570/01 poly(vinyl
chloride) film supplied by Klockner Pentaplast of America
(Gordonsville, Va.). The platen used to heat seal the lidding to
the blister component was heated to a temperature of 180.degree. C.
to obtain a peel-open package. Numerous blister packages of the
present invention were peeled open and each sample peeled cleanly,
which represents a significant improvement compared to blister
packages known in the art that utilize a paper/film/foil laminate
in the lidding which are prone to tearing during peeling.
1TABLE 1 Properties of Lidding Component for Example 1 Example 1
Conventional Lidding (nonwoven/foil) (paper/film/foil) Basis Weight
(g/m.sup.2) 102.7 72.5 MD Tensile Strength 123.4 73.7 (N/cm) XD
Tensile Strength 56.6 55.5 (N/cm) MD Elongation (% at 3 lbs) 0.117
0.097 XD Elongation (% at 3 lbs) 0.25 0.2 MD Elmendorf Tear (N)
1.16 1.11 XD Elmendorf Tear (N) 0.98 0.89 Spencer Puncture (J) 1.34
0.39 Thickness (mm) 0.144 0.093
EXAMPLE 2
[0067] This example demonstrates preparation of a lidding component
comprising a flash spun plexifilamentary sheet and a metalized
polyester film suitable for use in peel-open child-resistant
blister packages.
[0068] A multi-layer laminated sheet was prepared using an
extrusion lamination process with an Egan Coater/Laminator. First,
a permanent adhesive tie layer was used to bond a layer of
Tyvek.RTM. flash spun high density polyethylene sheet (Tyvek.RTM.
1073D, basis weight 74.6 g/m.sup.2, available from E.I. du Pont de
Nemours and Company (Wilmington, Del.)) to a metalized
poly(ethylene terephthalate) film (Mylar.RTM. 7100 metalized
(aluminum) film having a thickness of 12 microns, available from
DuPont-Teijin Films). The permanent adhesive tie layer was
Nucrel.RTM. 1214 ethylene methyl acrylate resin. The Nucrel.RTM.
1214 resin was extruded between the nonwoven and film substrates by
extruding onto the metalized side of the Mylar.RTM. polyester film
at a thickness of 0.5 mil and subsequently contacting the extruded
adhesive layer with the Tyvek.RTM.D flash spun sheet. The
Nucrel.RTM. copolymer was extruded using a single screw extruder
(with an exit temperature of 450.degree. F. (232.degree. C.)
through a feedblock with a 40 inch (101.6 cm) wide (internally
deckled to 28 inches (71.1 cm)) Cloeren edge bead reduction die
having 30 mil gap operated at 321.degree. C. and a backpressure of
500 psig (3447 kPa) to form a 0.5 mil thick adhesive layer. The air
gap between the die exit and the nip (where the extrudate contacts
the metalized film) was 6 inches (15.2 cm) and the lead-in was -0.5
inch (-1.27 cm). The line speed was 399 ft/min (122 m/min). The
side of the metalized Mylar.RTM. 7100 film that contacted the
Nucrel.RTM. adhesive was corona treated in-line at 3 kW prior to
extruding the adhesive layer. The Tyvek.RTM. flash spun sheet was
laminated to the adhesive-coated film and the assembly (Tyvek.RTM.
nonwoven/permanent Nucrel.RTM. adhesive/metalized Mylar.RTM. film)
was then passed over a chill roll having a matte finish and
operated at 10.degree. C.
[0069] The above assembly was then extrusion coated with a layer of
peelable heat-sealable sealant on the film side of the metalized
Mylar.RTM. film using the Egan Coater/Laminator. The peelable
sealant used was Appeel.RTM. 20D745 ethylene methyl acrylate
copolymer sealant. The film side of the metalized film was corona
treated in-line at 3 kW prior to coating with the sealant. The line
speed was 299 ft/minute (91 m/min), the extruder exit temperature
was 490.degree. F. (254.degree. C.), die width 40 in (101.6 cm)
(internally deckled to 28 inches (71.1 cm)), air gap 6 inches (15.2
cm), lead in of -0.5 inch (-1.27 cm), a Teflon.RTM.
fluoropolymer-coated pressure roll and a matte finish chill roll,
with a nip pressure of 60 psi (414 kPa). The laminate structure can
be processed on a blister packaging machine as the lidding
component to form a child-resistant blister package.
[0070] The properties of the lidding material are given in Table 2
below.
2TABLE 2 Properties of Lidding Component Comprising Flash Spun
Sheet and Metalized Film Property Example 2 Tensile Strength MD
(psi) 8614 Tensile Strength XD (psi) 9120 Graves Tear Strength MD
(N) 33.82 Graves Tear XD (N) 34.35 Elmendorf Tear MD (g/mm) 1990
Elmendorf Tear XD (g/mm) 2225 Spencer Puncture (J) 0.62 Oxygen
Transmission Rate 40.967 (cc/m.sup.2/24 hr) MVTR g/m.sup.2/24 hr
0.324
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