Note: Descriptions are shown in the official language in which they were submitted.
1~2;26~36
2301-1299
The present invention relates broadly to the contalner art, and
is more particwlarly concerned with a collapsible dispensing container o~
laminated wall construction in the body portion thereof, whereby product
permeation and absorption, and oxygen absorption are substantially prevent-
ed in all regions of the container structure susceptible thereto.
Collapsible tubes formed of metallic and plastic materials have
long been known in the packaging field. Extruded metal tubes are inherent-
ly brittle and repeated use not infrequently results in wall cracks so
that product is exuded from a location other than the essentially rigid
dispensing orifice. Of the prior art metal tubes, aluminum tubes, while
probably being the least brittle, are somewhat limited in their applications
since up to the present time it has not been possible to apply to the
interior surfaces thereof a completely satisfactory coating, when re~uired
to prevent attack and corrosion of the metal by alkaline or acid contents
and contamination of the contents by the reaction products. Notwithstand-
ing the relatively brittle nature of a metal tube, the mentioned internal
coating operation requires an additional processing step which necessarily
increases the cost of the final article.
Tubes formed of polyethylene and o~her plastic materials have
enjoyed wide commercial success in the packaging of many products; however,
certain other products after a time have been noted to deteriorate when
contained therein. Plastics as exemplified by polyethylene are permeable
to a degree when employed in the wall thicknesses used in tubular contain-
ers, and the essential oils embodied in most dentifrices for flavoring
purposes are reduced in volume during storage of the container, rendering
the den-tifrice less palatable. Also, the plastic container wall absorbs
oxygen over a period of timc and ultimately may decompose the product,
which has actually been tound to be the càse with ~luoride-containing tooth-
pastes.
It has accordingly been proposed to provide a relatively thin
, ,
USSN 567,002
~L2Z26~36
metallic ~oil barrier between the product and the polyethylene tube body to
prevent the mentioned loss of essential oils and the absorption of oxygen.
The metallic barrier has been suggested as an interlayer between facing
sheets of polyethylene, and that a laminate be formed by heat with or with-
out suitable adhesives. However, while a structure of this general
character is effective to prevent some permeation and oxygen absorption
through the tube body, and particularly when the inner thermoplastic layer
is a copolymer of an olefin and a polar group containing monomer which is
co-polymerizable therewith, there remains the possibility of product
deterioration albeit to a much lesser extent.
A disadvantage in a polyolefin surface resides in the inability
of the surface to readily receive printing or decorative material. In
addition, polyolefin has a memory effect, that is, it does not remain com-
pressed when squeezed; a particular disadvantage for dentifrice tubes.
To counter such lack of compressibility the metal layer must be relatively
thick so that its compressibility is imposed on the plastic.
It is, therefore, an important aim of the present invention to
provide a collapsible dispensing container of lalninated wall construction
in the body portion.
The invention preferably permits a tubular container having a
plurality of adherent layers in the body portion thereof to be formed,
one of said layers providing a barrier to product migration and oxygen
absorption such as a metallic foil and another of said layers being a mate-
rial selected from the group consisting of a fluoropolymer containing at
least ~0% by weight fluorine or copolymer or mixture thereof varying in
density and crystallinity. The latter layer being innermost and preferably
outermost with dif~erent additional laminae sandwiched therein between.
Such additional laycrs comprise paper and suitablo adhesive and
bonding agents such as copolymer of ethylene and acrylic acid. The
collapsible dispensing container of the~ present invention may be con-
~Z~2~6~36
structed from the laminated substrate of the present invention by conven-
tional and known apparatuses. Exemplary oE such equipment ancl method can
be discerned from United States patent No. 3,832,9~.
According to the present invention, there is provided a substrate
of layers of materials comprising a first layer of a fluoropolymer, a
second layer of metal foil, a third layer of paper and a fourth layer of a
fluoropolymer.
The invention also provides a collapsible paste dispensing con-
tainer of layers of materials comprising a first innermost layer of a
fluoropolymer, a second layer of metal foil, a third layer of paper and an
outermost fourth layer of a fluoropolymer.
In another aspect, the invention provides a method of producing
laminated tubes in which a tubular body is formed of a barrier layer and a
fluoropolymer or copolymer thereof laminated thereto; the laminated tube
body is then located on a forming member in adjacency to a barrier member
also positioned thereon.
In the drawings wherein lilce numerals are employed to designate
like parts throug}lout the same:
Figure 1 is a cross-sectional view of a fragmentary portion of a
laminated substrate of the present invention.
Figure 2 is a side elevational view of a collapsible dispensing
container embodying the novel concepts of this invention, with portions of
the body walls being broken away to more fully illustrate the laminated
structure.
Referring now first to Figure 1 of the drawings, a substrate 10 is
shown in cross-scction wheroby to reveal the components of the sandwich
that goes to mako up the lamlnated configuration.
It will be scen that the bottommost layer 11 is a ~luoropolymer.
The second layer 12 thereabovo is an adhesive layer which joins the fluoro-
12226~36
polymer layer 11 ~ th third layer 13 which is a metal foil such as aluminum
foil. The fourth layer 1~ is another adhesive that adhesively secures
the other surface of the metal foil layer 13 to a paper layer 15. The top-
most layer 16 is fluoropolymer.
The thermoplastic fluoropolymer of the present invention encom-
pass such polymers as copolymer of he~afluoropropene and tetrafluoro-
ethylene; tetrafluoro-
- 3~1 -
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--4--
ethylene; copolymer of heptafluoropropyl trifluorcvinyl ether
and tetraEluoroethylene; polychlorotrifluoroethylene and
polyvinylidene fluoride.
The applicable fluoropolymers and use are disclosed
in U.S. Patent 3,194,428. Such copolymers may be made by the
method described in U.S. Patent 2,549,935. They comprise 5-50%
by weight of hexafluoropropylene (preferably 5-15~) and 95-50%
: by weight of tetrafluoroethylene (preferably 95-85%), copolymer-
ized, to form normally solid resins which melt 20-~50F.
These fluoropolymers are particularly useful because
they have very low flavor absorption characteristics as can
be seen ~rom the following tables where fluoropolymers are
compared with polyethylene where the thicknesses of the layers
or coating are the same:
TABLE I
:~ ABSORPTION OF FLAVOR FROM A DENTIFRICE PASTE
(Aging Condition: 1 Week at Room Temperature)
Elavor Absorbed (%)
Copolymer of hexafluoropropene and
tetrafluoroethylene (Teflon* FEP) 0.2
Tetrafluoroethylene (Teflon TFE) 0.3
Copolymer of hepta~luoropropyl
trifluorovinyl ether and
tetrafluoroethylene (Teflon PFA~ 0.2
Polychlorotrifluoroethylene (Halar)* 0.4
Polyvinylidene Fluoride (PVDF) 0.9
Polyethylene 2.4
* Trade mark
~;ZZ2686
-4a-
TABLE II
ABSORPTION OF FLAVOR FROM A DENTIFRICE GEL
.
(Aging Condition: 2 Weeks at Room Temperature)
Flavor Absorbed (~)
Copolymer of hexafluoropropene and
tetrafluoroethylene (Teflon FEP) 0.1
Tetrafluoroethylene (Teflon TFE) 0.2
. .. 1~.
122~686
-5-
Copolymer of heptafluoropropyl
trifluorovinyl ether and
tetrafluoroethylene (Teflon PFA) 0.1
Polychlorotrifluoroethylene (Halar) 0.2
Polyvinylidene Fluoride (PVDF) 0.1
Polyethylene l.0
It is contemplated that within the purview of the
invention the adhesives ~ay be a copolymer of ethylene and
acrylic acid or methacrylic acid, or sodium or zinc salts
thereof in a diluent system.
The metal foil may be preferably alumiDum foil~
The paper layer is desirably a kraft paper.
The thicknecs range of each of the layers is as
follows:
Fluoropolymer layer ll 0.5 mils ~o 3.0 mils,
preferably 1.0 mils
Adhesive layer 12 - sufficient to assure adhere~ce
Metal foil layer 13 - 0.5 mils to 2.0 mils, preferably 1.0
mils.
Adhesive layer 14 - sufficient to assure adherence
Paper layer 15 - 1.5 mils to 2.5 mils, preferably 2.0 mils.
Fluoropolymer layer 16 - 3.5 mils ~o 5.0 mils, preferably
4.0 mils.
The topmost fluoropolymer layer 16 adheres to the
paper layer 15 by means of the application of sufficient
heat and pressure to the substrate. In the event the
application of heat and pressure is not appropriate a
suitable adhesive is to be employed.
Figure 2 is an example of the laminated structure of a
collapsible container with the layers being demonstrated as
in Figur~ 1 with layer 11 being inner most and the other
layer being of the same materials and in the same order as
shown.
It is believed manifest fxom the foregoing that
applicant has provided a collapsible container structure
which substantially reduces the problems heretofore unsolved
by the prior art. The laminated substrate and laminated
shoulder piece 20 completely eliminates product permeation
and oxygen absorption, and this highly desirable result is
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achieved by the use of low cost materials which pre:ferably are combin-
ed into laminated form in the manner :indicated in ~igure 2.
The outer layer of an fluoropolymer or copolymer thereof is
a thermoplastic capable of fusion during a side seaming step and
granting adequate protection to the paper and metallic foil interlayer.
However, the outer layer of -fluoropolymer and paper may be eliminated
if the foil barrier is of sufficient thickness to resist damage, and
by flowing a thermoplastic material into the overlap side seam during
the sealing thereof when such a system is employed.
Further, the outer layer may be paper in a -three-ply laminate
formed of paper, foil and a fluoropolymer and co-polymer thereof as
described. As the outermost and innermost layers are preferably the
same, the folded edges of the tube produced from the substrate is con-
veniently heat bonded. A suitable adhesive can be used when heat bonding
is not possible. This modification is in addition to the aforementioned
four-ply laminates comprised of from outside to in, fluoropolymer paper,
foil and fluoropolymer, or fluoropolymer 20 foil, paper and fluoropolymer.
It is contemplated that suitable adhesives will be employed between the
laminae whenever necessary. Li~e structures can be employed for the
shoulder piece, cap, neck, piston and in the construction of dispensing
valves for such containers, particularly in conjunction with the interior
portions exposed to the contained dentifrice, and, again, where required,
compatible adhesives would naturally be employed.
Various modifications of the invention have been disclosed here-
in, and these and other changes can of course be effected without de-
parting from the novel concepts of the instant contribution. Addition-
ally when cast as a film on the interior surfaces of fiber drums used for
the storage of flavored dentifrice, the material will retard flavor loss
into the drums, thereby extending storage life.
