DE7510858U - Sterilization-resistant and heat-sealable packaging sheet - Google Patents

Description

VAW Leichtmetall GmbH \ \ / " \ !?» ♦ «· · '*'"; Bonn

Sterilization-resistant and heat-sealable packaging material made of aluminum, aluminum alloys and / or aluminum composite materials

The innovation concerns a sterilization-resistant and heat-sealable one Packaging material made of aluminum, aluminum alloys and / or aluminum composite materials.

Sterilization-resistant and heat-sealable packaging is known, z. B. flexible composite films or deep-drawn semi-rigid or rigid packaging made of aluminum, aluminum alloys or aluminum composite material, preferably a film made of polyolefins on the side facing the filling material Possess polypropylene or higher density polyethylene. These foils are attached to the carrier material by means of an adhesive made of aluminum, aluminum alloys or aluminum composite material firmly bonded.

Processes for the production of 'heat sealables are also known and sterilization-resistant packaging materials in which a coating is applied to the carrier material will. However, the previously known methods have considerable disadvantages.

For example, DT-OS 1 586 288 describes a heat-sealable and sterilization-resistant one Container described, which has a thermosetting, sterilization-resistant layer on the inside Base of, z ,. B., phenolic and / or epoxy resins. To the-

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Close the container Jeiioch by means of a heat sealing process To be able to do so, a thermoplastic synthetic material must also be placed between the lid and the bottom of the container will.

In this process, a non-heat-sealable Paint applied to both container parts to be connected, this layer being used solely for the purpose of corrosion protection and serves to achieve adhesion of the following sealing layer. To seal these two To reach parts of the container ^ however, it is imperative to use a thermoplastic sealing medium as well, which is either applied in the form of an additional coating to the edge of one of the two container parts must be, or must be introduced in the form of an washer between the container parts to be closed. the The introduction of this thermoplastic layer, which is absolutely necessary for sealing the two container parts, is required considerable additional mechanical expenditure on sealing machines and also leads to a considerable increase in costs of the finished product, so that this known method is highly inefficient for mass-produced articles. It is also known to those skilled in the art that the thermoplastics described Do not have adequate resistance to sterilization. So the universal usability is this Packaging material significantly restricted,

Furthermore, in DT-PS 1 669 067 a method for Production of detachable heat seals described in which the sealing layer is a mixture of a phenol-formaldehyde resin and a polyamide resin and a solvent is applied to a carrier material, the two being to be sealed However, parts are provided with sealing layers of different compositions.

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In this known method is initially in the production of the material of great disadvantage that the two to sealing container parts have to be provided with varnishes of different compositions. Also, both are based Paintwork on raw materials that at least partially - as practice has shown - z. B. by the water swellability, are unsuitable for the interior painting of canned food or significantly limit their usability.

Another significant disadvantage of this known method is the fact that a proper elevation of the packs only by using an additional adhesion-promoting layer between the carrier material and the one described Coatings of lacquer can be achieved, which makes the production of this material more complicated and expensive and thus has similar disadvantages as the material claimed in DT-OS 1 586 288.

The innovation concerns a heat-sealable and sterilization-resistant one Packaging material made of aluminum or aluminum alloys and / or aluminum composite material, such as. B. Rigid or semi-rigid cans or flexible bags, with the feature that the side to be turned towards the contents of the Packaging material with a heat-sealable, sterilization-resistant, deep-bondable and filling material-resistant Layer is provided.

The advantage of the innovation is that this layer is applied firmly in one line and afterwards Drying or crosslinking of the paint components has a high thermoplasticity, with the sterilization resistance and the anti-corrosive effect is not impaired in any way, even against aggressive filling goods.

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Another advantage of the new -jsgeme coating is in that the seal seam strength in coordination with the shape and size of the pack with respect to the requirements Transport and storage and can be adapted to consumer needs in terms of opening options.

Another advantage of the material is that the parts of a packaging unit to be sealed, e.g. B. one Food can, in contrast to one of the known processes, are coated with paints of the same composition.

The advantages mentioned are achieved according to the invention by the fact that, for the paintwork, the Resistance to sterilization and filling goods as well as excellent thermoplasticity, a mixture of epoxy resins, Phenol-formaldehyde resins and polyester resins are used. To achieve the properties mentioned above For the resulting paintwork, it is necessary to adhere to the defined mixing ratios of the individual components.

The following mixing ratio of the individual components has proven to be particularly suitable:

Epoxy resin 20 - 35 %

Phenol formaldehyde resin 0.3 - 5 %

Polyester resin 2 - 10 %

Solvent 50 - 77 * 7 #

This mixture can be in accordance with the food law Provisions certain amounts of paint auxiliaries, such as. B. Resins, plasticizers, stabilizers and waxes be admitted.

The mixture is dissolved in suitable organic solvents on a carrier material, e.g. B. made of aluminum and aluminum

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nium alloys in a thickness range from 0.050 to 0.300 mm or aluminum verbvaican, ζ. Β. Aluminum foil in connection with suitable plastics, e.g. B. polyester, polyolefins and polyamide in dry layer thicknesses of 3 to 30 / um, preferably 7 to 15 µm. The drying and crosslinking of the The temperatures required for painting are in the order of magnitude of 170 to 350 ° C with dwell times between 20 seconds and 15 minutes.

It has been found that packaging materials with coatings produced in this way excellently against one another let seal, the sealing temperature in the range 160 to 320 ° C can be for sealing times as they are are common with today's packaging machines.

Example;

An aluminum strip 0.1 mm thick was given a conventional exterior paintwork on one side. the other side of the hinge, which, if the material is used as intended, will later be used as the inside of a deep-drawn container functions, was painted with the resin mixture described, dissolved in suitable solvents, at a drying temperature of 220 ° C and a residence time of 60 seconds. The dry film thickness was 10 to 12 μm.

This material was made into containers by deep drawing. These were filled with a test solution made from a 1.5 % aqueous acetic acid solution, which is customary for the can sector. The filled container was closed with a suitable lid, which was coated on the side facing the contents with the coating described above and also used for coating the inside of the can with a dry layer thickness of 10 to 12 Aim. The following closing conditions were chosen:

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Seal time 0.6 sec sealing temperature 290 ⁰ C.

After two hours of sterilization at 121 ° C., the container was sealed properly. The lid could be opened remove easily and residue-free from the container; the interior paintwork of the container and lid remained unchanged Image, no corrosion was found anywhere on the packaging.

A sample of the innovation is attached in two pieces.

7 -

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Claims (1)

Protection claims ., {sterilization-resistant and heat-sealable Verpaokungsbahn ^ made of aluminum, aluminum alloys and / or aluminum composite materials, characterized in that the dem The side of the packaging web facing the filling material with a heat-sealable, sterilization-resistant, deep-drawable one and filling material-resistant layer is provided. 2. Verpaokungsbahn naoh claim 1, characterized in that this layer consists of a mixture of epoxy resin, phenol-formaldehyde resin and polyester. 3 · Verpaokungsbahn according to claims 1-2, characterized in, that the mixing ratio of the individual components, expressed in percent by weight, is selected as follows: Epoxy resin 20 - 35 % Phenol-formaldehyde resin 0.3 - 5 % polyester resin 2 - 10 Ji 4. Packaging sheet according to claims 1-3 *, characterized in that the resins mentioned under claim 2 are dissolved in suitable solvents. 5. Packaging web according to claims 1-4, characterized in that this layer is in a dry layer thickness from 3 to 30 / µm, preferably 7 to 15 / µm, to the Ver = packing sheet is applied. 6. Packaging web naoh claims 1-5, characterized in that this layer in one or more lines, but is preferably applied in one stroke. 7510858 09/04/75