NO170522B - DISPENSER CONTAINER FOR PASTAS CONTAINING TASTE OIL AND WHICH HAVE A MULTILAYER STRUCTURE INCLUDING A BACKGROUND OF ETHYLENE PROPYLENE COPOLYMER - Google Patents

Description

The present invention relates to a dispenser container with a laminated wall construction in the body part, as product penetration and absorption, and oxygen absorption, are essentially prevented in all areas of the container structure that are susceptible to such.

Collapsible tubes formed from metal and plastic materials have long been known in the packaging field. Extruded metal tubes are inherently fragile and repeated use not infrequently results in wall breaks so that product seeps out from somewhere other than the essentially rigid dispensing opening. Among the previously known metal tubes, aluminum tubes, although they are probably the least fragile, are somewhat limited in their applications as it has not been possible to apply a completely satisfactory coating to the inner surfaces when this is required to prevent attack and corrosion of the metal by alkali or acid content and contamination of the contents with the reaction products. Notwithstanding the relatively fragile nature of a metal tube, the aforementioned inner coating operation requires an additional processing step which necessarily increases the cost of the final article.

Tubes formed from polyethylene and other plastic materials

has had wide commercial success in the packaging of many products; however, certain other products have been shown to deteriorate after some time when they have been stored in such. Plastic substances such as e.g. polyethylene, are permeable to a certain extent when used in the wall thicknesses used in tubular containers, and the essential oils found in most toothpastes for flavoring purposes are reduced in volume during storage of the container, making the toothpaste less palatable. In addition, the plastic container wall absorbs oxygen over time and can eventually break down the product, which has actually been shown to be the case with fluoride-containing toothpastes. A further disadvantage of a plastic tube lies in the surface's inability to easily receive printing or decoration material. In addition, plastic tubes, such as polyethylene,

a memory effect; i.e. that they do not remain compressed when squeezed, a particular disadvantage for toothpaste tubes.

In order to counteract the above-mentioned problems, it has consequently been proposed to provide a metal foil barrier between the product and the polyethylene tube body. This would counteract the compression problem in that the metal layer would impose its compressibility on the plastic. In addition, the metal foil barrier between the product and the polyethylene tube body would prevent the aforementioned loss of essential oils and the absorption of oxygen. The metal barrier has been proposed as an intermediate layer between surface sheets of polyethylene, and that a laminate should be formed by heating with or without suitable binders. Although a structure of this general nature is effective in preventing some product permeation and oxygen absorption through the tube body, and particularly when the inner thermoplastic layer is a copolymer of ethylene and a monomer containing a polar group which is co-polymerizable, the possibility remains for product deterioration, albeit to a much lesser extent.

Attention is drawn to the following prior art.

US Patent No. 3,295,725 describes a tube that combines the above-mentioned advantages of an aluminum tube with the advantages of a plastic tube. This is a laminated, collapsible dispensing container that contains both a metal barrier and an inner wall of polyethylene. The thermoplastic layer can be roughly described as polyolefin and a copolymer of an olefin and a monomer containing a polar group that can be copolymerized. This laminate overcomes the limitations described above, except for the absorption of essential oils from the toothpastes.

Canadian patent no. 72 8 525 describes a laminated tube containing an inner layer of polyethylene. The problem of flavor oil absorption in the thermoplastic wall was recognised.

US Patent No. 4,096,946 describes a laminated packaging where vinylidene chloride is used as the inner layer, and an outer layer of copolymer of ethylene and propylene. However, this is not a tube; the container does not contain any metal and there is no mention of the copolymer's taste-blocking properties.

US Patent No. 4,207,363 describes a laminate film used for packaging meat which contains a propylene-ethylene copolymer as the outer layer. This is not a tube either; the container does not contain any metal and there is no mention of the copolymer's taste-blocking properties.

In addition, US Patent No. 4,405,667, US Patent No. 4,308,084 and US Patent No. 4,279,344 describe laminated packaging articles containing ethylene-propylene copolymer. None of these articles were tubes, however, and no mention was made of the copolymer's taste-blocking properties.

It is therefore an important aim of the present invention to provide a dispenser container with a laminated wall construction in the body part.

Another object of the invention lies in the provision of a tube container with several glued together layers in the body part, one of the layers constituting a barrier against product migration and oxygen absorption, namely a metal foil, and another of the layers an ethylene-propylene copolymer or a mixture thereof that varies in density and crystallinity. The latter layer lies at the innermost and outermost with various additional thin layers placed in between.

Such additional layers include paper and suitable adhesives and binders such as e.g. copolymer of ethylene and acrylic acid. The dispenser container according to the present invention can be constructed from the laminated base using conventional and known devices. An example of such equipment and method can be found in US Patent No. 3,832,964.

According to the present invention, there is thus provided a dispenser container for pastes containing flavor oil, which has a multi-layered structure comprising a barrier layer bordering the paste, a second layer of metal foil, a third layer of paper and a fourth layer of ethylene propylene copolymer, which is characterized by the fact that the barrier layer 11 consists of ethylene propylene copolymer.

In the drawing, where equal numbers are used to denote equal parts, Fig. 1 is a cross-sectional view of a fragmented part in a

laminated base according to the present invention.

Fig. 2 is a side view of a collapsible dispenser container comprising the new concept according to the invention, parts of the body walls being broken away to more fully illustrate the laminated structure.

Reference is first made to fig. 1 in the drawing where a base (10) is shown in cross-section to reveal the constituents of the layer division which gives the laminated configuration.

It will be seen that the bottom layer (11) is a copolymer of ethylene and propylene. The second layer (12) above the first is a binder layer which binds the layer (11) of ethylene-propylene copolymer to the third layer (13) which is a metal foil, which e.g. aluminum foil. The fourth layer (14) is another binder which attaches the second surface of the metal foil layer (13) by binding to a paper layer (15). The top layer (16)

is ethylene-propylene copolymer.

The ethylene-propylene copolymer is particularly useful as it has very low absorption properties for taste, as will be seen from the tables below comparing ethylene-propylene copolymer with polyethylene, and the thickness of the layers or coating being the same:

Within the scope of the invention, the binders are intended

to be a copolymer of ethylene and acrylic acid or methacrylic acid, or sodium or zinc salts thereof in a diluent system.

The metal foil can preferably be aluminum foil.

It is desirable that the paper layer is a kraft paper. The thickness range for each of the layers is as follows: The layer of ethylene-propylene copolymer (11): 12.7 - 76.2 µm, preferably 25.4 µm. Adhesive layer (12): sufficient to ensure gluing. Metal foil layer (13): 12.7 - 50.8 µm, preferably 25.4 µm. Glue layer (14): sufficient to ensure gluing. Paper layer (15): 38.1 - 63.5 µm, preferably 50.8 µm. Layer of ethylene-propylene copolymer (16): 88.9 - 127 µm, preferably 101.6 µm.

The top layer of ethylene-propylene copolymer (16) is attached to the paper layer (15) by applying sufficient heat and pressure to the base. If the supply of heat and pressure is not suitable, a suitable adhesive must be used.

Fig. 2 is an example of the laminated structure of a collapsible container, the layers being shown as in fig. 1 with layer (11) on the inside and the other layers are of the same materials and in the same order as shown.

It should be obvious from the above that the applicant has provided a collapsible container structure which substantially reduces the problems which have so far been unsolved within the prior art. The laminated base and the laminated shoulder piece (20) virtually eliminate all product penetration and oxygen absorption.

The outer layer of an ethylene-propylene copolymer is a thermoplastic which can fuse during a side folding step and provide suitable protection for the intervening paper and metal foil layers. The folding technique for a collapsible toothpaste tube of the general type described here can be found in US Patent No. 3,295,725.

Copolymers of ethylene and propylene can also be used for the shoulder piece, the cap, the neck, the piston and in the construction of outlet openings for other containers for dental care products, especially together with the internal parts that are exposed to the content of dental care products, and again, of course, for - single adhesives are used when required.

Claims (1)

Dispenser container for pastes containing flavor oil, having a multilayer structure comprising a barrier layer (11) bordering the paste, a second layer (13) of metal foil, a third layer (15) of paper and a fourth layer (16) of ethylene propylene copolymer , characterized in that the barrier layer (11) consists of ethylene propylene copolymer.