Note: Descriptions are shown in the official language in which they were submitted.
~X~ 33
--1--
SUBSTRATE CONTAINING POLYPROPYLENE AND ARTICLES MADE THEREFROM
FIELD OF THE INVENTION
The present invention relates broadly to the container
art, and is more particularly concerned with a collapsible
dispensing container of laminated wall construction in the
bod~ portion thereof, whereby product permeation and
absorption, and oxygen absorption are substantially prevented
in all regions of the container structure susceptible
thereto.
BACKGROUND OF THE INVENTION
Collapsible tubes formed of metallic and plastic
materials have long been known in the packaging field.
Extruded metal tubes are inherently 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 required to
prevent attack and corrosion of the metal by alkaline or
acid contents and contamination of the contents by
the reaction products. Notwithstanding 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 other plastic mate-
rials have enjoyed wide commercial success in the packagingof 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
containers, and the essential oils embodied in most
dentifrices for flavoring purposes are reduced in volume
during storage of the container, rendering the dentifrice
less palatable. Also, the plastic container wall absorbs
oxygen over a period of time and ultimately may decompose
the product, which has actually been found to be the case
1;~8~683
--2--
with fluoride-containing toothpastes. A further
disadvantage of a plastic tube resides in the inability of
the surface to readily receive printing or decorative
material. In addition, plastic tubes, as exemplified by
polyethylene, have a memory effect; that is, they do not
remain compressed when squeezed, a particular disadvantage
for dentifice tubes.
To counter the above problems, it has accordingly been
proposed to provide a metallic foil barrier between the
product and the polyehtylene tube boby. This would counter
the compressibility problem in that the metal layer would
impose its compressibility upon the plastic. In addition,
the metallic foil barrier between the product and
the polyethylene tube body would prevent the mentioned
lS 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 without suitable adhesives. However, while
a structure of this general character is effective to
prevent some product permeation and oxygen absorption
through the tube body, and particularly when the inner
thermoplastic layer is a copolymer of ethylene and a polar
group containing monomer which is co-polymerizable therewith,
there remains the possibility of product deterioration
albeit to a much lesser extent.
PRIOR ART
The Attention is directed to the following prior art:
Marchak (Can. Patent No. 728,525) discloses a laminated
tube containing an inner layer of polyethylene. He
recognized the problem of absorption of flavor oil by the
thermoplastic wall, and suggested the use of nylon to
overcome this.
Herrero (U.S. Patent No. 4,139,665) discloses a
laminate which does not contain metal. This laminate uses
polypropylene, among others, as the inner layer, in order
to act as a barrier against moisture and water vapor. A
thermoplastic acrylonitrile copolymer serves as the flavor
barrier. This laminate is different from the present
invention in that it does not contain a metallic foil.
Furthermore, Herrero failed to recognize the efficacy of
polypropylene as a flavor barrier.
~ 6~3 62301-1349
Yoshio et. al. (U.S. Patent No. 3,958,721) teach a
collapsible, laminated tube which also does not contain a metal
sheet. Although this tube contains polypropylene, they note
that the low permeability to odor and the high resistance to
oil is provided by the polyvinyl alcohol film.
None of the above cited references specifies polypro-
pylene as the inner layer of collapsible laminated tubes con-
taining metallic foilsO In those cases in which polyolefins
are mentioned, no indication is made of high resistance to
absorption of essential flavor oils. In fact, the problem with
polyethylene is its high flavor absorption.
It has been demonstrated herein, surprisingly, that
polypropylene, a chemical closely related to polyethylene, is
substantially non-absorbable to flavor oils. The tube contains
polypropylene as the innermost and outermost layers, paper,
aluminum foil, and an adhesive, as intermediate layers.
SUMMARY OF THE INVENTION
It is, therefore, an important aim of the present
invention to provide a collapsible dispensing container of
laminated wall construction in the body portion.
q~
Another objcat of this invention lies in the provi-
sion of a tubular container having a plurality of adherent
layers in the body portion thereof, one of said layers provid-
ing a barrier to product migration and oxygen absorption such
as a metallic foil and another of said layers being polypropy-
lene or copolymer or mixture thereof varying in density and
crystallinity. The latter layer being innermost and preferably
outermost with different additional laminae sandwiched therein
between.
Such additional layers comprise paper and suitable
4 623~ .34'.
adhesive and bonding agents such as copolymer of ethylene and
acrylic acid. Ihe collapsible dispensing container of the
present invention may be constructed from the laminated
substrate of khe present :invention hy conventional and lcnown
apparatuses. Exemplary of such equipment and method can be
discerned from U.S. patent No. 3 832 964. A further object of
the instant invention is to provide a method of producing
laminated tuhes in which a tubular body is formed of a barrier
layer and a polypropylene or copolymer tl1ereof laminated
thereto; the 1aminated tuhe body is then :I.ocated on a forming
member in acljacency to a harrier rnember also positioned
thereon.
According to the present invention there is providecl
a collapsible dispersing contalner for a paste composition
comprising one or more flavour oils said container comprising
a first innermos~. layer of a polypropylene a second layer of
metal foil a third layer of paper and an outermost fout-th
layer of polypropylene.
Preferably the fir.t. layer of polypropylene :is
secured to the metal foil with an adhesive. Preferahly also
the third layer of paper i5 secured to the fourth layer of
po].ypropylene with an adhesive. A particularly preferred
adhesive is a copolymer of ethylene and acrylic acid or
methacrylic acid~
The container is useful for paste compositions
especially dentifrices which comprise one or more flavour oils.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawincJs wherein like numerals are employed to
designate like parts throughout -the same:
~Z80683
- 4a - 62301-1349
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.
DETAILED DESCRIPTION OF THE INVENTION
The thermoplastic of the present invention is poly-
propylene.
Referring now first to Figure 1 of the drawings, a
substrate 10 is shown in cross-section whereby to reveal the
components of the sandwich that go to make up the laminated
configuration.
It will be seen that the bottommost layer 11 is a
polypropylene. The second layer 12 thereabove is an adhesive
layer which ~oins the polypropylene layer 11 with third layer
13 which is a metal foil such as aluminum foil. The fourth
layer 14 is another adhesive that adhesively secures the other
surface of the metal foil layer 13 to a paper layer 15. The
topmost layer 16 is polypropylene.
The polypropylene is particularly useful because it
has very low flavor absorption characteristics as can be seen
from the following tables where polypropylene is 15 compared
with polyethylene where the thicknesses of the layers or coat-
ing are the same;
,~
B~83
--5--
TABLE I
Polymer Absorption of Neat Flavor Oil
Absorption (~)
Polypropylene Tenite 4230G
(Eastman) 1.3
Polypropylene F12OF
tUnited States Steel)1.6
Polypropylene FP200F
(United States Steel)2.3
Polypropylene Vestrolen P3200
(Huls Plastic) 2.3
Low density polyethylene
Tenite 154 (Eastman) 5.5
Low density polyethylene
Lupolen 1804H (BASF)5.6+0.14
TABLE II
Loss of Flavor from Flavored Dentifrice into Polymers
Flavor Loss*
Polypropylene Tenite 4230G
(Eastman) 31
Polypropylene F120F
(United States Steel)38
Polypropylene F200F
(United States Steel)38
Low density polyethylene
Lupolen 1804H (BASF) 100
Low density polyethylene
Tenite 154 (Eastman) 130
*Relative to BASF low desity polyethylene arbitrarily
set at 100; the lower the number the less flavor lost
from the dentific.
lZ8~G~33
TABLE III
Relative Flavor Absorption into Polymers
from Flavored Dentifrice*
72F 90F 120F
Aluminum 0 0 0
Polypropylene FP200F
(United States Steel) 34 51 55
Polypropylene F120
(United States Steel~ 55 68 73
Low density polyethylene
6560 (ARCO) 76 76 83
Low density polyethylene
NPE853 (Norchem) 69 76 104
Low density polyethylene
Lupolen 1804H (BASF) 100+19 107+14 119+10
*All numbers relative to BASF low density polyethylene
set at 100 at 72F; the lower the number the less flavor
absorbed.
It is contemplated that within the purview of
the invention the adhesives may 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 aluminum foil.
The paper layer is desirably a kraft paper.
The thickness range of each of the layers is as
follows:
Polypropylene layer 11 0.5 mils to 3.0 mils,
preferably 1.0 mils
Adhesive layer 12 - sufficient to assure adherence
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.
Polypropylene layer 16 - 3.5 mils to 5.0 mils, preferably
4.0 mils.
The topmost polypropylene 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
6~33
- 7 - 62301-1349
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 Figure 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 from 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 a barrier shoulder
piece substantially eliminates product permeation and oxygen
absorption.
The outer layer of a polypropylene is a thermoplastic
capable of fusion during a side seaming step and granting ade-
quate protection to the paper and metallic foil interlayer.
The art of seaming of a collapsible dentifrice tube of the
general type herein disclosed can be seen in U.S. Patent
No. 3,295,725. ~owever, the outer layer of polypropylene 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 polypropylene 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 convenient]y heat bonded. A
suitable adhesive can be used when heat bonding is not possi-
ble. This modification is in addition to the aforementioned
four-ply laminate comprised of from outside to in, polypro-
pylene, paper, foil and polypropylene. It is conte~plated that
~"
6~33
7a - 62301-1349
suitable adhesives will be employed between the laminae when-
ever necessary.
Polypropylene can also be employed for the shoulder
piece, cap, neck, piston and in the construction of dispensing
valves for o~her dentiErice dispensers, particularly in
conjunction with the interior portions exposed to the contained
dentifrice, and, again, where required, compatible adhesives
would naturally be employed.
- æ~3
Additionally when cast as a film on the interior
surfaces of fiber dxums used for the storage of flavored
dentifrice, the material will retard flavor loss
into the drums, thereby extending storage life.
Various modifications of the invention have been
disclosed herein, and these and other changes can of course
be effected without departing from the novel concepts of the
instant contribution.
