IE56191B1 - Laminated polyester containing substrate and collapsible dispensing container made therefrom - Google Patents

Abstract

A laminate of inner and outer layers (11, 16) of polyethylene terephthalate or another polyester, having sandwiched therebetween a metal foil layer (13) (13) and a paper layer (15) each adhering to its neighbours, is used in fabricating a collapsible dentifrice tube.

Description

Pries Mtp 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 body portion thereof, whereby product permeation and absorption, and oxygen absorption, are substantially prevented 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 inherently brittle and repeated use not infrequently results in wall cracks so that product is extruded from a location other than the essentially rigid dispensing orifice. Of the prior art metal tubes, aluminium 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 infernal coating operation requires an additional processing step which necessarily increases the cost of the final articles.

Tubes formed of polyethylene and other plastic materials have enjoyed wide commercial success in the packaging of many products; however, certain other products after a time have been noted to - 2 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 flavouring 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 with fluoride-containing toothpastes.

It has accordingly been proposed to provide a relatively thin metallic foil 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 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 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 compressed 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.

An object of the present invention lies in the provision of a collapsible paste dispensing container of multi-layer material, of which the innermost layer is a polyester.

The polyester is preferably a polyalkylene material, for example polyethylene terephtalate or polybutylene terephtalate, or a copolymer with a minor amount of another dicarboxvlic acid with variable density, melting point, and crystallinity. The outermost layer may also be of polyester, with different additional laminae sandwiched between the inner and outer layers. - 3 Such additional layers may comprise paper and suitable adhesive and bonding agents such as copolymer of ethylene and acrylic acid. The collapsible dispensing container of the present invention may be made using conventional and known apparatus. Examples of such apparatus and method can be discerned from U.S. Patent No. 3,832,964, which is incorporated herein by reference.

The invention also extends to a collapsible paste dispensing container containing a composition the ingredients of which include an essential oil or oils, the container being made of layers of materials comprising a first innermost layer of a polyester, a second layer of metal foil, a third layer of paper and an outermost fourth layer of a polyester.

The invention may be carried into practice in various ways and one embodiment will be described by way of example with reference to the accompanying drawings, in which:Figure 1 is a cross-sectional view of a fragmentary portion of a laminated substrate for use in making a container in accordance with the present invention: and 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-section whereby to reveal the components of the sandwich that goes to make up the laminated configuration.

The bottommost layer 11 is a polyester. The second layer 12 thereabove is an adhesive layer which joins the polyester layer 11 with a third layer 13 which is a metal foil such as aluminium foil. The fourth layer 14 is another adhesive that secures the other surface of the metal foil layer 13 to a paper layer 15. The topmost layer 16 is a polyester. - 4 The thermoplastic polyester useful in the present invention encompass such polyalkylene terephthalates as polyethylene terephthalate and polybutylene terephthalate.

Some polyester resins suitable for this kind of container are disclosed in U.S. Patent Specifications Nos. 3,152,515 and 4,197,326, and the disclosures are incorporated into this specification by reference.

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 aluminium foil.

The paper layer is desirably a kraft paper.

The thickness range of each of the layers is as follows: Polyester layer 11 - 0.5 mils to 3.0 mils (0.0127 to 0.0762 mms), preferably 1.0 mils (0.0254 nans); Adhesive layer 12 - sufficient Metal foil layer 13 - 0.5 mils preferably 1.0 mils (0.0254 irons); Adhesive layer 14 - sufficient Paper layer 15 - 1.5 mils to 2 preferably 2.0 mils (0.0508 irons); fo ensure adherence; fo 2.0 mils (0.0127 fo 0.0508 irons), to ensure adherence; mils (0.0381 to 0.0635 irons), Polyester layer 16 - 3.5 mils fo 5.0 mils (0.0889 to 0.127 irons), preferably 4.0 mils (0.1016 irons).

The topmost acetal polyester 16 adheres to the paper layer 15 by means of the application of sufficient heat and pressure to the - 5 substrate. If 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 Figure 1 with layer 11 being innermost and the other layers being of the same materials and in the same order as shown.

It is believed manifest from the foregoing that a collapsible container structure has been provided which substantially reduces the problems heretofore unsolved by the prior art. The laminated substrate and laminated shoulder piece 20 substantially eliminate product permeation and oxygen absorption, and this highly desirable result is achieved by the use of low cost materials which preferably are combined into laminated form in the manner indicated in Figure 2.

The polyester of the outer layers is a thermoplastic capable of fusion during a side seaming step and giving adequate protection to the paper and metallic foil interlayers. 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, incorporated herein by reference.

However, the outer layer of polyester and paper may be eliminated if the foil barrier is of sufficient thickness to resist damage; if the tube is made with an overlapping side seam, a thermoplastic material may be caused to flow into the overlapping side seam during the sealing operation.

Further, the outer layer may be paper in a three-ply laminate form of paper, foil and polyalkylene terephthalate or other polyester as described. As the outermost and innermost layers are preferably the same, the folded over overlapped edges of tubes produced from the substrate are conveniently formed by heat bonding. 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 - polyester, paper, foil, and polyester; or polyester, foil, paper and polyester. It is contemplated that suitable adhesives will be employed between the laminae whenever necessary. Similar - 6 laminated structures can be employed for such components as shoulder pieces, caps, necks, rods, pistons and dispensing valves, particularly where an interior surface is exposed to the contained dentifrice, and again, where required, compatible adhesives would naturally be employed.

Attention is directed to GB Application Ho. 32398/84 Serial i’o. 2151986 which claims a substrate of layers of materials comprising a first layer of a polyester, a second layer of rnatal foil, a third layer of paper and a fourth layer of a polyester.

The polyethylene terephthalate (PET) is particularly useful because it has very low flavour absorption characteristics as can be seen from the following tables where PET is compared with polyethelene where the thicknesses of layers or coating are the same: TABLE I ABSORPTION OF FLAVOUR FRCffi A DENTIFRICE PASTE (Aging Condition: 1 week at Room Temperature)? Flavour Absorbed (¾) PET 0.1 PET Aluminized (P/z - 2 ohm) 0.0 PET Aluminized (2-3 ohm) 0.0 Nylon 6,6 0.5 Polyethylene 2.4 TABLE II ABSORPTION OF FLAVOUR FROM A DENTIFRICE GEL (Aging Condition: 2 weeks at Room Temperature) Flavour Absorbed (%) PET 0.0 PET Aluminized (l^/g - 2 ohm) 0.0 PET Aluminized (2-3 ohm) 0.0 Nylon 6,6 0.2 Polyethylene 1.0

Claims (13)

1. A collapsible paste dispensing container of multi-layer material, containing a composition the ingredients of which include an essential oil or oils of which the innermost layer is a polyester.

2. A container as claimed in Claim 1, in which the outermost layer is a polyester.

3. A container as claimed in Claim 1 or Claim 2, including an intermediate layer of paper.

4. A container as claimed in any of Claims 1 to 3, including an intermediate layer of metal foil.

5. A collapsible paste dispensing container containing a composition the ingredients of which include an essential oil or oils the container being made of layers of materials comprising a first innermost layer of a polyester, a second layer of metal foil, a third layer of paper and an outermost fourth layer of a polyester.

6. The container of any of Claims 1 to 5, wherein the polyester is a copolymer of an alkylene terephthalate.

7. - The container of any of Claims 1 to 5, wherein the polyester is polyethylene terephthalate.

8. The container of any of Claims 1 to 5, wherein the polyester is polybutylene terephthalate.

9. The container of any of Claims 4 to 8, wherein a layer of the polyester is secured to the metal foil with an adhesive.

10. The container of any of Claims 3 to 9, wherein the layer of paper is secured to a layer of the polyester with an adhesive.

11. The container of Claim 9 to Claim 10, wherein the adhesive is a - 8 copolymer of ethylene and acrylic acid.

12. A paste dispensing container constructed and arranged sub5 stantially as herein specifically described with reference to Figure 2 of the accompanying drawings.

13. A paste dispensing container containing a composition the ingredients of which include an essential oil or oils the container 10 being constructed and arranged substantially as herein specifically described with reference to Figure 2 of the accompanying drawings.