FI85242B - HOPTRYCKBAR BEHAOLLARE FRAMSTAELLT AV ETENPROPENKOPOLYMER. - Google Patents

Description

1 85242

This invention relates generally to the container field, and more particularly to a collapsible dispensing container having a laminated wall structure in the body that prevents product passage and absorption and oxygen absorption in substantially all sensitive areas of the container.

The packaging industry has long known for collapsible tubes made of metal and plastic materials. Extruded metal tubes are inherently brittle and repeated use often results in cracks in the wall so that the product exudes from a location other than a substantially rigid dispensing opening.

Of the prior art metal tubes, aluminum tubes, although probably the least brittle, have somewhat limited applications, as it has not hitherto been possible to apply a completely satisfactory coating to their inner surfaces when it is required to prevent alkali and acidic corrosion and contamination of the metal. Despite the relatively fragile nature of the metal tube, said internal coating operation requires an additional process step which necessarily increases the cost of the final product.

Tubes formed of polyethylene and other plastic materials have enjoyed general commercial success in the packaging of many products; certain other products have been found to disperse after a certain period of time when used for packaging. Plastics, such as polyethylene, are to some extent permeable when used as wall thicknesses used in tubular containers, and the volume of essential oils contained in most toothpastes for seasoning purposes decreases during container storage, making toothpaste less pleasant. Similarly, the wall of the plastic container absorbs oxygen over time and can eventually break down the product, as has actually been observed with fluoride toothpastes. An additional disadvantage of the plastic tube is that the surface is not easily able to receive printing or decorative material. In addition, plastic pipes, such as polyethylene, have a memory effect; i.e., they do not remain compressed when compressed, which is a particular disadvantage of toothpaste tubes.

To counter the above problems, it has therefore been proposed to attach a layer of metal foil between the product and the body of the polyethylene tube. This alleviates the compressibility problem so that the metal layer would give its compressibility to the plastic. In addition, a metal foil barrier layer between the product and the body of the polyethylene tube would prevent said loss of essential oils and oxygen absorption. A metal barrier layer has been proposed as an intermediate layer between opposing polyethylene films and to form a laminate by heat with or without suitable adhesives. However, although such a structure is effective in somewhat preventing product passage and oxygen absorption through the tube body, and especially when the inner thermoplastic layer is a copolymer of ethylene and a polar group-containing monomer copolymerizable therewith, the product remains degradable. , although to a much lesser extent.

Attention is drawn to the following prior art: U.S. Patent 3,295,725 discloses a tube which combines the above advantages of an aluminum tube and a plastic tube. This is . . ·. laminated, collapsible dispensing container containing both a metal barrier and a polyethylene inner wall. The thermoplastic layer is generally described as a polyolefin and a copolymer formed by an olefin and a polar group-containing monomer copolymerizable therewith. This laminate avoids the limitations described above except for the absorption of essential oils from toothpaste.

CA Patent 728,525 discloses a laminated tube containing an inner layer of polyethylene. Here we are aware of the problem that the thermoplastic wall absorbs spice oils.

U.S. Pat. No. 3,854,242 to U.S. Pat. No. 4,096,946 discloses a laminated package using vinylidene chloride as the inner layer and a copolymer of ethylene and propylene as the outer layer. However, this is not a tube; it does not contain metal; and none of the aroma barrier properties of the copolymer were mentioned in this U.S. patent.

U.S. Patent 4,207,363 discloses a laminate film used to package meat and containing a propylene-ethylene copolymer as an outer layer. This is also not a tube; it does not contain metal; and this U.S. patent does not mention any of the aroma barrier properties of the copolymer.

In addition, U.S. Patents 4,405,667, 4,308,084 and 4,279,344 disclose laminated packaging products containing an ethylene-propylene copolymer. However, none of these products were a tube and no mention was made of the aroma barrier properties of the copolymer.

Therefore, it is an important object of the present invention to provide a collapsible dispensing container having a body portion with a laminated wall structure.

Another object of the present invention is to provide a tubular container having a plurality of adhesive layers in the body, one of which provides a barrier to product migration and oxygen absorption, such as a metal foil, and the other of said layers is an ethylene-propylene copolymer or a mixture thereof. and crystallinity vary. The latter layer is the innermost and preferably the outermost layer and various additional lamellae are sandwiched between them.

- - Such additional layers include paper and suitable adhesives and binders, such as a copolymer of ethylene and acrylic acid. The collapsible dispensing container of the present invention can be formed from the laminated substrate of the present invention by conventional and known devices. An example of such an apparatus and method can be found in U.S. Patent 3,832,964, which is incorporated herein by reference.

It is a further object of the present invention to provide a method of making laminated tubes in which a tubular body is formed from a barrier layer and an ethylene-propylene copolymer is laminated thereto; the laminated tube body is then placed against the forming member against a barrier layer member which is also placed thereon.

Other objects and advantages of the present invention will become more apparent as the description proceeds.

In the drawings, in which the same numerals are used to refer to the same parts in both: Figure 1 is a cross-sectional view of a small portion of the laminated substrate of the present invention; Figure 2 is a side elevational view of a collapsible dispensing container incorporating the novel ideas of the present invention, with portions of the runqo walls of the portions cut open to show the laminated structure in more detail.

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

Referring first to Figure 1 of the drawings, there is shown a cross-section of the substrate 10 revealing the components of the layer structure required to form the laminated structure.

- - It is observed that the bottom layer 11 is an ethylene-propylene copoly -!.! mers. The second layer 12 on it is an adhesive layer connecting the ethylene-propylene copolymer layer 11 to a third layer 13, which is a metal foil, such as an aluminum foil. The fourth layer 14 is a second adhesive that firmly adheres the second surface of the metal foil layer 13 to the Daper layer 15. The top layer 16 is an ethylene-propylene copolymer.

- ”· Ethylene-propylene copolymer is particularly useful because it has very low aroma absorption properties, as can be seen from the following tables comparing ethylene-propylene copolymer to polyethylene when the thickness of the coating layers is the same: 5 85242

Table I

Absorption of undiluted spice oil into the polymer (2 weeks contact)

Polymer Weight Gain (%)

Aluminum 0

Ethylene-propylene copolymer Rigidex 40 (British Petroleum) 4.8

Low density polyethylene Tenite 154 (Eastman) 5.5

Low density polyethylene

Lupolen 1804 H (BASF) 5.6 + 0.14

High density polyethylene LR (USI) 5.9

Ionomer Surlyn 1707 (DuPont) 15.7

Ionomer Surlyn 1605 (DuPont) 19.0

Ionomer Surlyn 1706 (DuPont) 24.3

Table II

Relative absorption of the flavoring substance into the polymers X) after a contact time of 3 months with toothpaste. X X)

Polymer Flavor absorbed

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

Ionomer Surlyn 1707 1557

Ionomer Surlyn 1605 at 1672 x ^ 32.2 ° C X X) ____ Relative to low density polyethylene arbitrarily set at 100; the lower the number, the less flavor is absorbed.

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It is contemplated that within the scope of this invention, the adhesives may be a copolymer of ethylene and acrylic acid and methacrylic acid or their sodium or zinc salts in a diluent system.

The metal foil may preferably be an aluminum foil.

The paper layer is preferably kraft paper.

The thickness range of each layer is as follows:

Ethylene propylene copolymer layer 11 0.013-0.076 mm, preferably 0.025 mm.

Adhesive layer 12 - sufficient to ensure adhesion.

Metal foil layer 13 to 0.013 to 0.051 mm, preferably 0.025 mm. Adhesive layer 14 - sufficient to ensure adhesion.

Paper layer 15 to 0.038 to 0.064 mm, preferably 0.051 mm. Ethylene propylene copolymer layer 16 to 0.089 to 0.127 mm, preferably 0.103 mm.

The top ethylene-propylene copolymer layer 16 adheres to the paper layer 15 by applying sufficient heat and pressure to the substrate. In the event that the use of heat and pressure is not appropriate, a suitable adhesive must be used.

Figure 2 is an example of a laminated structure of a collapsible container, in which the layers are shown as in Figure 1 with the layer 11 being inner and the other layers being of the same materials and in the same order as shown therein.

. It is believed from the foregoing that the present invention provides a collapsible container structure that substantially reduces problems not previously solved by the prior art. The laminated substrate and laminated protrusion 20 substantially eliminate product permeation and oxygen absorption.

The outer layer of ethylene-propylene copolymer is a thermoplastic that is able to fuse together during the side sealing step and provides adequate protection for the paper and metal foil interlayer. The sealing technique for a collapsible toothpaste tube of the general type disclosed herein can be found in U5 Patent 3,295,725, which is incorporated herein by reference.

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However, the outer layer of ethylene-propylene copolymer and paper can be eliminated if the outer layer of foil is thick enough to resist damage, and by draining the thermoplastic material into the adhesive side seam during sealing when such a system is used.

Further, the outer layer may be paper in a three-layer laminate formed of paper, foil and ethylene-propylene copolymer as described. Since the outer and inner layers are preferably the same, the bent edges of the tube formed of the substrate are easy to heat seal. A suitable adhesive can be used when heat sealing is not possible. This modification is an addition to the above-mentioned four-layer laminate consisting externally to internally of ethylene-propylene copolymer, paper, foil and ethylene-propylene copolymer. It is intended that suitable adhesives be used between the lamellae whenever necessary.

Ethylene-propylene copolymers can also be used to form dispensing valves for the cantilever, cap, neck, plunger and other toothpaste dispensers, especially when the interiors are exposed to the toothpaste they contain and, again, naturally compatible adhesives are used when required.

In addition, when the material is cast as a film on the inner surfaces of the pulp barrels used to store the flavored toothpaste, it slows down the loss of flavor to the barrels, which extends the shelf life.

Various modifications of the invention are set forth herein, and these and other modifications may, of course, be made without departing from the novel ideas of this disclosure.

Claims (6)

A container of laminated material layers, comprising a first layer (11) of ethylene propylene copolymer, 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 adjacent to the container contents layer (11) consists of ethylene propylene copolymer. Container according to claim 1, characterized in that the first layer (11) of ethylene-propylene copolymer is attached to the metal foil by adhesive (12). Container according to claim 1, characterized in that the third layer (15) of paper is attached to the fourth layer (16) of ethylene propylene copolymer by adhesive. Container according to claim 1, characterized in that the first layer (11) of ethylene-propylene copolymer is attached to the metal foil (13) by means of glue (12) and the third layer (15) of paper is attached to the fourth layer (16) of ethylene-propylene copolymer by means of glue. Container according to claim 4, characterized in that the adhesive is a copolymer of ethylene and acrylic acid. Container according to any of claims 1-5, characterized in that it is a compressible dosing container for paste consisting of laminated material layers.