CA1222686A

CA1222686A - Laminated fluoropolymer containing substrate and collapsible dispensing container made therefrom

Info

Publication number: CA1222686A
Application number: CA000471127A
Authority: CA
Inventors: Edward A. Tavss; Samuel C. Temin
Original assignee: Colgate Palmolive Co
Current assignee: Colgate Palmolive Co
Priority date: 1983-12-30
Filing date: 1984-12-28
Publication date: 1987-06-09
Also published as: SE8406433D0; NO163764B; GB2151985B; ZA849956B; PH20780A; MX170971B; DK618284A; SE463908B; GB8701497D0; GB8432397D0; NO163764C; JPS60228145A; SE8406433L; GB2184394A; AU564676B2; ZW21984A1; NO845267L; DE3445798A1; GB2184394B; BR8406757A

Abstract

ABSTRACT OF THE DISCLOSURE

There is disclosed a substrate of layers of materials comprising fluoropolymer layers having sandwiched therein between a metal foil layer and a paper layer all suitably adhered to one another, the substrate being useful in fabricating a dentifrice tube and thereby substantially pre-venting product permeation and absorption, and oxygen absorption.

Description

1~2;26~36 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 -iZ~26~6 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 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 ~- 122~6~;

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.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. 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.

2. The substrate of claim 1 wherein the fluoropolymer is a copolymer of hexafluoropropene and tetrafluoroethylene.

3. The substrate of claim 1 wherein the fluoropolymer is a tetrafluoroethylene.

4. The substrate of claim 1 wherein the fluoropolymer is a copolymer of heptafluoropropyl trifluorovinyl ether and tetrafluoroethylene.

5. The substrate of claim 1 wherein the fluoropolymer is a copolymer of polychloratrifluoroethylene and polyvinyl-idine fluoride.

6. The substrate of claim 1 wherein the first layer of the fluoropolymer is secured to the metal foil with an adhesive.

7. The substrate of claim 1 wherein the third layer of paper is secured to the fourth layer of the fluoropolymer with an adhesive.

8. The substrate of claim 1 wherein the first layer of the fluoropolymer is secured to the metal foil with an adhesive and wherein the third layer of paper is secured to the fourth layer of the fluoropolymer with an adhesive.

9. The substrate of claim 8 wherein the adhesive is a copolymer of ethylene and acrylic acid.

10. A collapsible paste dispensing container of layers of materials comprising a first innermost layer of a fluoro-polymer, a second layer of metal foil, a third layer of paper and an outermost fourth layer of a fluoropolymer.

11. The container of claim 10 wherein the fluoropolymer is a copolymer of hexafluoropropene and tetrafluoroethylene.

12. The container of claim 10 wherein the fluoropolymer is a tetrafluoroethylene.

13. The container of claim 10 wherein the fluoropolymer is a copolymer of heptafluoropropyl trifluorovinyl ether and tetrafluoroethylene.

14. The container of claim 10 wherein the fluoropolymer is a copolymer of polychlorotrifluoroethylene and polyvinylidine fluoride.

15. The container of claim 10 wherein the first layer of the fluoropolymer is secured to the metal foil with an adhesive.

16. The container of claim 10 wherein the third layer of paper is secured to the fourth layer of the fluoro-polymer with an adhesive.

17. The container of claim 10 wherein the first layer of the fluoropolymer is secured to the metal foil with an adhesive and wherein the third layer of paper is secured to the fourth layer of the fluoropolymer with an adhesive.

18. The container of claim 18 wherein the adhesive is a copolymer of ethylene and acrylic acid.