LU86231A1 - LAMINATE SHEET BASED ON ETHYLENE-PROPYLENE COPOLYMER AND CRUSHABLE CONTAINER MADE THEREFROM - Google Patents

Description

"# 14 <

The present invention relates generally to the packaging technique and it relates more particularly to a collapsible container-dispensing container whose body has laminated walls, which practically avoids permeation and absorption of the product as well as the absorption of oxygen in all parts of the container where these can occur.

Crushable tubes made of plastics and metallic materials have been known for a long time in the field of packaging. Ex-extruded metal tubes are brittle by nature and it is not uncommon for repeated use to result in breakage of the wall, so that the product escapes through a place other than the orifice of essentially rigid distribution. Among the metal tubes of the state of the art, aluminum tubes, although probably the least annoying, are of relatively limited application, since it has not been possible so far to apply are completely satisfactory on the internal surface of these when necessary to prevent attack and corrosion of the metal by acid or alkaline contents and contamination of the contents by the reaction products. In addition to the relatively brittle nature of a metal tube, the mentioned internal coating operation requires an additional manufacturing step which necessarily increases the cost price of the finished article.

Tubes made of polyethylene and other plastics have had great commercial success in packaging many products; however, it has been observed that some other products deteriorate after some time when contained in these tubes. Plastics, such as polyethylene, are to some extent permeable when used in the wall thicknesses used for tubular containers, and essential oils incorporated into more than one tooth - f // / 2 4 frices to flavor them reduce volume during storage of the container, which makes the toothpaste less pleasant. Likewise, the wall of the plastic container absorbs oxygen over a period of time, and may eventually decompose the product, which has indeed been shown to be the case with toothpastes containing fluorine. Another disadvantage of a plastic tube is the inability of the surface to easily receive prints or decorations. In addition, the plastic tubes, such as polyethylene for example, exhibit a memory effect, that is to say that they do not remain compressed once pressed, which represents a particular drawback for toothpaste tubes.

In order to solve the above problems, it has therefore been proposed to place a sheet metal barrier between the product and the body of the polyethylene tube. This would solve the problem of compressibility, since the metal layer would impose its compressibility on the plastic. In addition, the metal foil barrier between the product and the body of the polyethylene tube would prevent the loss of essential oils and the above-mentioned absorption of oxygen. It has been proposed that the metal barrier is in the form of an intermediate layer between facing polyethylene sheets and that a laminate is formed by heat, with or without suitable adhesive. However, although a structure of this type succeeds to some extent in preventing product permeation and absorption of oxygen through the body of the tube, and in particular when the inner thermoplastic layer is a copolymer of With ethylene and a polar group-containing monomer which is copolymerizable therewith, there is still, although to a much lower degree, the possibility of deterioration of the product.

Brandt (US Patent 3,295,725) describes a tube which combines the above-mentioned advantages of an aluminum tube with the advantages of a plastic tube. It is a collapsible collapsible dispenser container comprising both a metal barrier and an internal wall 5 of polyethylene / The thermoplastic layer is generally described as consisting of polyolefin and a copolymer of an olefin and a monomer containing a polar group which is copolymerizable with it. This laminate solves the aforementioned problems, except 10 with regard to the absorption of essential oils from toothpastes.

Marchak (Canadian Patent 728,525) describes a laminate tube containing an inner layer of polyethylene.

This author has noted the problem of the absorption of flavoring oil by the thermoplastic wall.

Cook (US Patent 4,096,946) describes a laminate package using vinylidene chloride as an inner layer and an outer layer of ethylene and propylene copolymer. However, it is not a tube; -It does not contain metal, and Cook did not mention. properties of the copolymer as a flavor barrier.

Anthony (US Patent 4,207,363) describes a laminated film used for packaging meats, the outer layer of which consists of a propylene-ethylene copolymer. Nor is it a tube; it does not contain metal, and Anthony did not mention the properties of the copolymer as a flavor barrier.

In addition, Christensen (US Patent 4,405,667), Ohtusu-ki (US Patent 4,308,084) and Holloway (US Patent 4,279,344) 30 disclose laminated packaging articles containing an ethylene-propylene copolymer. However, none of these items was a tube, and no mention was made of the properties of the copolymer as a flavor barrier.

An important object of the present invention is therefore to provide a collapsible dispensing container 4, the body of which has a laminated wall.

Another object of the invention is to provide a tubular container, the body of which comprises several adherent layers, one of said layers providing a barrier to the migration of the product and to the absorption of oxygen, such as that a metal foil, and another of said layers consisting of ethylene-propylene copolymer or of a mixture of the latter of density and. variable crystallinity, this last layer being the most internal and preferably the most external, with additional different sheets inserted between cel 1 es ci-ci.

Such additional layers include paper as well as suitable binders and adhesives, such as a copolymer of ethylene and acrylic acid. The collapsible dispensing container of the present invention i can be made from the laminate support of the present invention by conventional and known machines.

Examples of this tool and these techniques can be found in US Patent 3,832,964.

Another object of the present invention is to provide a process for the manufacture of laminate tubes, wherein a tubular body consists of a barrier layer and an ethylene-propylene copolymer applied thereon; the body of the laminated tube is then placed on a forming member in contact with a barrier element also disposed thereon.

The rest of this description will reveal other objects and advantages of the invention.

In the accompanying drawings, the same numbers are used to designate the same parts: - FIG. 1 is a cross-sectional view of a fragment of a laminate substrate of the present invention.

- Fig. 2 is a side view of a collapsible dispensing container embodying the new concepts of the present invention, portions of the body walls / 5 4 5 (being shown in exploded view to better represent the laminate structure.

The thermoplastic of the present invention is an ethylene-propylene copolymer.

Referring now to Figure 1 of the drawings, a support 10 is shown in cross section, which allows to show the components of the sandwich which constitute the layered configuration.

It can be seen that the lowest layer 11 10 is an ethylene-propylene copolymer. The second layer 12 which comes after this is a layer of adhesive which connects the layer of ethylene-propylene copolymer 11 with the third layer 13 which is a metal sheet, such as an aluminum sheet. The fourth layer 14 is another adhesive which fixes the other side of the metal foil layer 13 by adhesion to a layer of paper 15. The upper layer 15 consists of ethylene-propylene copolymer.

The ethylene-propylene copolymer is particularly useful because it is distinguished by a very low flavor absorption, as can be seen from the following tables, in which the ethylene-propylene copolymer is compared to polyethylene, the thicknesses layers or coatings being identical: 25 6 f · I "

TABLE I

Absorption of pure flavoring oil by polymers (2 weeks of contact) 5 Polymer Weight increase (%) _

Aluminum 0

Ethylene-propylene copolymer

Rigidex 40 (British Petroleum) 4-, 8

Low density polyethylene ·] q Tenite 154 (Eastman) 5.5

Low density polyethylene

Lupolen 1804H (BASF) 5.6 - 0.14

High density polyethylene • LR (USI) 5.9 15 Ionomer.

Surlyn 1707 (Dupont) 15.7

Ionomer;

Surlyn 1605 (Dupont) t 15.0

Ionomer 20 Surlyn 1706 (Dupont) 24.3

TABLE II

Relative absorption of aroma by polymers after contact with toothpaste for 3 months **

Aroma polymer absorbed ** 25 Ethylene-propylene copolymer "Rigidex 40 (British Petroleum) 59

High density polyethylene, LR (USI) 84

Low density polyethylene, NA (USI) 100 - 13

Ionomer, Surlyn 1706 893 30 'Ionomer, Surlyn 1707 1557

Ionomer, Surlyn 1605 1672 * At 32.2 ° C (90 ° F) ** Relative absorption compared to the absorption of low density polyethylene which has been arbitrarily designated 35 by 100; the lower the value, the less the aroma is absorbed.

r "7

It is intended that in the scope 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.

The metal sheet may preferably be an aluminum sheet.

It is desirable that the layer of paper be; Kraft paper.

The thickness of each of the layers is within? 10 1 are the following limits: | The thickness of the ethylene-propylene copolymer layer 11 ranges from 0.0125 mm to 0.076 mm, preferably being equal to 0.025 mm; ; the adhesive layer 12 is thick enough to ensure adhesion.

The thickness of the layer of metallic foil 13 d; ΐ ranges from 0.0125 mm to 0.05 mm, preferably being equal to / - 0.025 mm.i j- The layer of adhesive 14 is sufficiently thick t.

20 to ensure adhesion.

The layer of paper 15 has a thickness ranging from 0.038 mm to 0.063 mm, preferably equal to 0.05 mm.

The layer of ethylene-propylene copolymer 16 a j: a thickness ranging from 0.089 mm to 0.125 mm, preferably equal to 0.10 mm.

j The ethylene copolymer layer is made to adhere; propylene upper 16 to the paper layer 15 per app. plication of sufficient heat and pressure - on! the support. In case the application of heat and pressure is not suitable, an appropriate adhesive can be used; prayed.

Figure 2 is an example of the layered structure; _ Fied of a collapsible container, the layers being shown as in Figure 1, the layer 11 being the innermost and the other layers being made of the same materials and in the same order as shown in the figure.

8

The foregoing description clearly shows that the applicant has provided a collapsible container structure which greatly reduces the problems which have not been solved so far in the state of the art.

The laminate support and the laminated shoulder piece 20 practically prevent permeation of the product and absorption of oxygen.

The outer layer of an ethylene-propylene copolymer is a thermoplastic which can melt during the formation of a side seal and provide adequate protection for the paper and the intermediate metal foil layer. The technique for joining the edges of a tube of collapsible toothpaste of the general type described here can be found in US Pat. No. 3,295,725.

The outer layer of ethylene-propylene copolymer and paper can, however, be removed if the metal barrier is thick enough not to be damaged and, if such a system is used, by causing a thermoplastic to flow in the overlap of the side seal 20 when sealing it.

In addition, the outer layer may be paper in a 3-layer laminate made of paper, metal foil and an ethylene-propylene copolymer as described. Since the outermost layer and the innermost layer are preferably identical, it is convenient to heat-bond the folded edges of the tube made from the support. When the hot bond is not; not possible, · an appropriate adhesive can be used, this i: modification comes in addition to the aforementioned 4-layer laminate h • 30 'which comprises, from outside to inside, an ethylene-propylene copolymer, paper, a metallic foil and an ethylene-propylene copolymer. It is intended that appropriate adhesives are used between the layers if necessary.

Ethylene-propylene copolymers can be used; for the part of the shoulder, the stopper, the neck, the piston and in the construction of dispensing valves for other toothpaste dispensers, particularly with regard to the internal parts exposed to the contained toothpaste, and again , of course, suitable adhesives can be used if necessary.

In addition, if applied as a film to the internal surfaces of hard cardboard drums used for storing scented toothpaste, the material slows down the loss of aroma in the drums, which prolongs the duration of storage. .

(• i

Claims (10)

1. Substrate consisting of layers of materials, characterized in that it comprises a first layer of an ethylene-propylene copolymer, a second layer of metal foil, a third layer of paper and a fourth layer of a copolymer ethylene-propylene. 2. Substrate according to claim 1, characterized in that the first layer consisting of ethylene-propylene copolymer is fixed to the metal sheet with an adhesive. 3. Substrate according to claim 1, characterized in that the third layer of paper is fixed to the fourth layer of ethylene-propylene copolymer with an adhesive. 15 4 - Substrate according to claim 1, characterized in that the first layer of ethylene-propylene copolymer is fixed to the metal sheet with an adhesive, t and in that the third layer of paper is fixed to the fourth layer of ethylene-propylene copolymer with an adhesive. 5. Substrate according to claim 4, characterized in that the adhesive is a copolymer of ethylene and acrylic acid. 6. Crushable pulp dispenser container made of layers of materials, characterized in that it comprises a first internal layer of an ethylene-propylene copolymer, a second layer of metal foil, a third layer of paper and a fourth outer layer of an ethylene-propylene copolymer. 30 7 - A container according to claim 6, characterized in that the first layer of ethylene-propylene copolymer is fixed to the metal sheet with an adhesive. 8. Container according to claim 6, characterized in that the third layer of paper is fixed to the fourth layer of ethylene-propylene copolymer with an ad hey if f. »5 * η 9. Container according to claim 6, characterized in that the first layer of ethylene-propylene copolymer is fixed to the metal sheet with an adhesive, and in that the third layer of paper is fixed to 5] a fourth layer of ethylene-propylene copolymer with an adhesive. 10. Container according to claim 9, characterized in that the adhesive is a copolymer of ethylene and acrylic acid. · - :.....AT. - · * ·>., * ► * · · f .-- .. A i .- \ - 2 / ·; , .a Jua / tvOu- 2) 0--13- ^ 6 L- '' dd 'J.