Dispensing container made from an ethylene vinyl alcohol containing laminated material and the material therefor

(42) Date of commencement of the patent: 15. 4.1991 (45) Date of issue: 25.10.1991 (30) Priority:

(73) Patent owner:

28.12.1984 US 687555 claims.

COLGATE-PALMOLIVE COMPANY 10022 NEW YORK (US).

(54) LAMINATE AND DISPENSER MADE THEREOF (57) A laminate comprising ethylene vinyl alcohol copolymer layers sandwiching therebetween a metal foil layer and a paper layer, all of which are adhesively bonded together, is described. The laminate can be used to make a toothpaste tube.

<img file="AT393475B_D0001.tif" />

CQ

AT 393 475 mr oora-as

AT393 475B

The present invention relates to containers, and more particularly to compressible dispensers whose container portion is formed of laminated walls, wherein product permeation and absorption as well as oxygen absorption are substantially suppressed in all susceptible areas of the container .

In the packaging sector, compressible tubes made of metal or plastic have been known for a long time Tubes made of extruded metal are brittle, and prolonged use often leads to fractures, so that the product exits from a location other than the substantially rigid dispensing opening of the known metal tubes are aluminum tubes, which are probably the least brittle, limited in scope, since it was not possible until today, to apply a really satisfactory coating on their inner surfaces, if it was necessary to prevent attack and corrosion of the metal by alkaline or acidic ingredients and contamination of the contents by the reaction products. In addition to the relatively brittle nature of a metal tube, it is added that said inner coating requires an additional manufacturing step, which necessarily increases the price of the finished article

Polyethylene and other plastic tubes are used to package many materials; it has been observed that certain goods spoil in such packages after some time. Plastics, such as polyethylene, are permeable to some extent when used in the wall thicknesses used for tube-shaped containers. The essential oils contained in most taste-giving toothpastes decrease in volume during storage of the container, making the toothpaste less palatable. Furthermore, the wall of the plastic container will absorb oxygen over time, and eventually the product will decompose, as indeed observed with fluoride toothpastes. Another disadvantage of Kunststoffftübe is that their surface is not able to readily accommodate printing or decorative material. Furthermore, plastic tubes, for example those made of polyethylene, have a memory effect; d. that is, they do not remain compressed after squeezing, which is particularly detrimental to toothpaste tubes.

Accordingly, in order to address the above-mentioned problems, it has been proposed to provide a metal foil barrier layer between the fabric and the polyethylene tube body. Here, the compressibility problem is met by the metal layer transferring its compressibility to the plastic. Further, the metal foil barrier layer between the fabric and the polyethylene tube body prevents the aforementioned loss of essential oils and the absorption of oxygen. The metal barrier layer has been proposed as an intermediate layer between adjacent polyethylene films, and a laminate is to be formed by heat with or without suitable adhesives. While a structure of this general type prevents some degree of product permeation and oxygen absorption by the tube body, this is particularly true when the inner thermoplastic layer is a copolymer of ethylene and a polar group-containing monomer which is copolymerizable with the former is. Nevertheless, the possibility of decomposition of the product remains, albeit to a much lesser extent.

In US-PS 3,295,725 a tube is described in which the above-mentioned advantages of an aluminum tube are combined with the advantages of a plastic tube. It is a laminated squeezable dispensing container that includes both a metal barrier layer and a polyethylene inner wall. The thermoplastic layer is broadly described as a polyolefin and a copolymer of an olefin and a polar group-containing monomer copolymerizable therewith. This laminate overcomes the limitations described above except for the absorption of the essential oils from the toothpastes.

From CA-PS 728 525 a laminated tube is known which contains an inner layer of polyethylene. The problem of absorption of flavor oil by the thermoplastic wall is discussed.

U.S. Patent 4,261,482 discloses a laminated compressible tube having an ethylene vinyl alcohol copolymer outer layer and an olefin inner layer. The function of the ethylene vinyl alcohol copolymer is to serve as an oxygen barrier resin. This tube differs from the container according to the invention in two main respects. On the one hand, it does not contain a metal barrier layer as the central layer, and therefore does not have the above-described advantages of a metal layer. In the second place, ethylene vinyl alcohol copolymer is not the layer in contact with the toothpaste. The following information shows the value of the ethylene-vinyl alcohol copolymer as a flavor-saving layer when placed next to toothpaste

Further uses of ethylene vinyl alcohol copolymers in laminates have been described as an oxygen barrier, but in no case has its effectiveness been recognized as a flavor barrier. Furthermore, in none of these cases has the article been described as a compressible laminated tube containing a metal barrier. US Pat PPS 4,239,829, 4,254,169, 4,182,457.3, 620,435.4, 284,671.4, 464,443.4, 425,410 and 3,958,721.

Further, an ethylene-vinyl alcohol copolymer was also used as part of a laminate structure, but also they did not have the form of a squeezable tube containing a metal barrier layer. Again, the excellent flavor barrier properties of this polymer were not recognized. Examples are US Pat. Nos. 4,407,873,4406,667.4,400,428,4352,850.4451,512 and 4,410,595.

-2AT 393 475 B

According to US Pat. No. 4,284,674, an ethylene-vinyl alcohol copolymer has also been used as a heat insulator. Again, this did not exhibit the shape of a compressible laminated tube.

It is therefore an important object of the present invention to provide a collapsible dispensing container whose body has a laminated wall construction

Another object of the invention is to provide a tube-shaped container having a plurality of adherent layers in its body, one such layer being a metal foil, a barrier against product migration and oxygen absorption, and another of these layers being an ethylene-vinyl alcohol copolymer a mixture of the same is of different density and crystallinity. The latter layer forms the inner layer and preferably the outer layer, wherein between them various other laminate layers are arranged.

These further layers include paper and suitable adhesives and binders, e.g. As a copolymer of ethylene and acrylic acid.

The compressible dispenser according to the invention can be prepared from the laminate film of the invention using conventional and known apparatuses. Examples of such an apparatus and method can be taken from US Pat. No. 3,832,964, which is hereby incorporated by reference.

The object of the invention is also to provide a process for producing laminated tubes in which a tube body is made of a barrier layer and an ethylene-vinyl alcohol copolymer laminated thereon; the laminated tube body is then brought together on a molding with a barrier member also located on this.

In the following the invention will be explained in more detail with reference to figures in which like numerals always indicate the same parts; show it:

Figure 1 shows a cross section through a piece of a laminate according to the invention and

Figure 2 is a side view of a collapsible dispenser container embodying the inventive concept, with portions of the container wall removed to reveal the laminate structure.

The thermoplastic according to the invention is an ethylene-vinyl alcohol copolymer.

Referring first to Figure 1, a substrate 10 is shown in cross-section, revealing the components of the sandwich-type structure that make up the laminate assembly.

It can be seen that the lowermost layer (11) is an ethylene-vinyl alcohol copolymer. The second layer (12) above is an adhesive layer comprising the ethylene-vinyl alcohol copolymer layer (11) with the third layer (13) comprising a metal foil such as an aluminum foil. isL connects. The fourth layer (14) is another adhesive adhering the other surface of the metal foil layer (13) to a paper layer (15). The uppermost layer (16) is an ethylene-vinyl alcohol copolymer.

The ethylene-vinyl alcohol copolymer is particularly suitable because it exhibits very low taste-absorbing properties, which is evident from the following tables, in which an ethylene-vinyl alcohol copolymer is compared to polyethylene, the thicknesses of the layers or coatings being the same.

JabsllgJ

Flavor content of toothpaste in contact with polymers *

<td>Polvm "</td><td>Flavor concentration (%) **</td>

<td>none</td><td></td>

<td>(Comparative Experiment)</td><td>100</td>

<td>Ethylene vinyl alcohol</td><td></td>

<td>EF-F (Kuraray)</td><td>100</td>

<td>Low polyethylene »Density</td><td>15-19</td>

<td>Surlyn 1707</td><td>10 - 14</td>

<td>Surlyn 1706</td><td>5 - 9</td>

<td>Surlyn 1605</td><td>5 - 9</td>

* 15 minutes of contact at 32 ° C ** Based on the comparative experiment in which no polymer was in contact with the toothpaste; the greater the concentration of flavor, the more inert the polymer.

-3AT393475B

tables

Absorption of undiluted flavor oil by polymers (completely immersed for 2 weeks)

<td>polymer</td><td>Weight gain (%)</td>

<td>Ethylene vinyl alcohol</td><td></td>

<td>EF-F (Kuraray)</td><td>0.8</td>

<td>Low density polyethylene</td><td></td>

<td>(USI)</td><td>10</td>

<td>Surlyn 1707 (DuPont)</td><td>15</td>

<td>Surlyn 1605 (DuPont)</td><td>19</td>

<td>Surlyn 1706 (DuPont)</td><td>24</td>

Tables!

Relative flavor exudation by polymers after 3 months contact with toothpaste *

<td>Polvmer</td><td>Absorbed by the Polvmer Flavoring agents **</td>

<td>Ethylene vinyl alcohol</td><td></td>

<td>EF-F (Kuraray)</td><td>12</td>

<td>Low density polyethylene</td><td></td>

<td>(USD</td><td>100 ± 13</td>

<td>Surlyn 1706 (DuPont)</td><td>893</td>

<td>Surlyn 1707 (DuPont)</td><td>1557</td>

<td>Surlyn 1605 (DuPont)</td><td>1672</td>

* At 32 ° C ** Based on the low density polyethylene arbitrarily set at 100; the smaller the number, the less flavor was absorbed.

In the present invention, the adhesive may be a copolymer of ethylene and acrylic acid or methacrylic acid or their sodium or zinc salts in a diluent system.

The metal foil is preferably aluminum foil.

The paper layer is preferably kraft paper.

The respective thickness of the layers is in the range of:

12.7 gm to 76.2 gm, preferably 25.4 gm, for the ethylene vinyl alcohol copolymer layer (11), sufficient thickness to ensure adhesion, for the adhesive layer (12),

12.7 gm to 50.8 gm, preferably 25.4 gm, for the metal foil layer (13), sufficient thickness to ensure adhesion, for the adhesive layer (14),

38.1 gm to 63.5 gm, preferably 50.8 gm, for the paper layer (15) and

88.9 gm to 127.0 gm, preferably 101.6 gm, for the ethylene vinyl alcohol copolymer layer (16).

The topmost ethylene vinyl alcohol copolymer layer (16) adheres to the paper layer (15) by applying sufficient heat and pressure to the laminate. If the application of heat and pressure is not appropriate, a suitable adhesive is used

Figure 2 shows an example of a compressible container of the laminate, in which as shown in Figure 1, the layers are shown, wherein the layer (11) is the innermost layer and the other layers of the same materials in the same order as shown in Figure 1 consist.

By virtue of the compressible container according to the invention, the aforementioned disadvantages of the prior art are overcome. The laminated container body and the laminated shoulder piece (20) completely prevent

-4AT393 475B product permeation and oxygen absorption.

The outer layer of ethylene vinyl alcohol copolymer is a thermoplastic material which is weldable at the side seaming step and which provides adequate protection to the paper and metal foil interlayer. The suture formation in a compressible toothpaste tube of the general type described herein is described in U.S. Patent 3,295,725, which is hereby incorporated by reference herein. The outer layer of ethylene vinyl alcohol copolymer and paper may be omitted if the barrier film has sufficient thickness to withstand damage; In this case, a thermoplastic material is introduced into the overlapping seam area when welding it.

Further, in a three-layer laminate of paper, metal foil and an ethylene-vinyl alcohol copolymer as described, the outer layer may be made of paper. Since the outermost and innermost layers are preferably the same, the fold edges of the manufactured tubes are conveniently heat-sealed. A suitable adhesive may be used if heat welding is not possible. This modification is added to the above-mentioned four-day laminates, from outside to inside, ethylene vinyl alcohol copolymer, paper, film and ethylene vinyl alcohol copolymer.

Suitable adhesives have been used between the laminate layers, if necessary.

Ethylene vinyl alcohol copolymers can be used for the shoulderpiece, cap, neck, piston and donor valve assembly or for other toothpaste dispensers, especially in conjunction with the internal parts exposed to the toothpaste in the container, and also Of course, if necessary, suitable adhesives can be used here.

When the material according to the invention is applied as a film to the inner surfaces of the drums of fibrous material used for the storage of the flavored toothpastes, the material according to the invention slows down the loss of flavoring substances in the drums and thereby increases the storage stability.

Various modifications of the invention have been disclosed, and these and other changes may be made without departing from the novel concepts of the invention.