DE4306348A1 - Process for detaching aluminium layers and all material layers possibly lying thereover from plastics lying thereunder which are not films - Google Patents

Abstract

Published without abstract.

Description

The invention relates to a method for separating Aluminum layers and any overlying ones Material layers of underlying plastics, that do not represent slides, according to the preamble of Claim 1.

Plastic parts are used for a wide variety of applications provided with aluminum layers. This can be both be optical as well as purely decorative purposes. Because of the sensitivity of the aluminum layers to mechanical stresses such as B. Be scratching these aluminum layers with one or more Provide protective layers. These are mostly Layers of paint. In addition, these layers of paint can still with different layers of decoration such. B. Printing inks.

With aluminum and various other material layers provided plastic parts find z. B. Application as optical data carriers such as compact discs, CD-Roms, photo and Video plates and reflectors for lamps and automotive Headlights.

There are no large-scale technical solutions for any of these products Recycling plants where the plastic is sorted is recovered again.

When recycling is done, it is common shred coated plastic parts and through Remelt to process new products. The Properties of the recyclate are due to the incorporated foreign substances in the form of material Layers much worse than that of the respective  New plastics. Any optical data carriers must be shredded to protect copyrights. The The ground material obtained is usually deposited.

For reflectors in automotive headlights, recycling Process contemplated in which the plastic dissolved and the insoluble aluminum and other material Layers are separated by filtration. Therefor large amounts of organic solvents are required. To sort plastics from optical data carriers there is a procedure in which the Aluminum and other material layers through mechanical processes brushed or worn. A clean partition without damaging the but there is hardly any plastic underneath feasible. In a further process, the Paint layer peeled off with methanol before thanks to that Aluminum is dissolved. This procedure is only for suitable paints attacked by the methanol become. But there are a number of networked Methanol-resistant paints are used, where the Procedure fails. The effort is also due to the Use of solvents and the additional Drying relatively high.

The invention specified in claim 1 is The problem is based on a method for simple separation of aluminum and overlying material layers of underlying plastics, which are not foils, too create.

This problem is solved by the in claim 1 listed features solved.

The process is based on the surprising effect that by dissolving the aluminum layer, the one Interlayer between a plastic part that is not Is foil, and represents various layers of material, a complete and rapid separation of these  Layers of the plastic part is carried out. It is possible to use the aluminum in alkaline or dissolve acidic media.

The advantages achieved with the invention exist especially in that with the method described separation of multi-layer composites with aluminum can be carried out as an intermediate layer. The Plastics can be removed from the layers then be separated. So it is possible recover single-grade plastics from the composite and reuse it. The properties of the pure plastics recovered advantageously due to the particularly gentle Process in the field of new goods.

In contrast to other existing methods the described ecologically and economically cheaper. The fact that the described methods no organic solvents be used and the method is not of the type and Depending on the thickness of the paintwork or other layers is.

This is particularly useful and advantageous Process possible separation of layers from Plastic parts without damage or destruction what allows the plastic parts to be reused.

With aluminum, the dissolution is due to its base Character particularly light and advantageous in diluted Leaching possible.

A particular advantage lies in the fact that the Dissolve the aluminum and the used alkali again reforms so that no fresh sodium hydroxide solution is supplied must become. The resulting dissolved Al cations precipitate out of solution as aluminum hydroxide and can be removed from the process by filtration. The lye is therefore circulated and thereby continuously filtered.  

By simultaneous mechanical stress on the Plastic parts through shredding and / or through strong rubbing of the particles and / or by the accelerated spraying of the agent (turbo washing) the duration of the procedure is accelerated. The same effect occurs when the temperature increases, when the Alkali concentration and when using ultrasound on.

Through the use of ultrasound is also simultaneous a simplified separation of the material layers and achieved their comminution to small particles. By the shredding of the material layers will Sorting to clean plastics simplified.

A simplified separation of material layers will achieved by adding surfactants and glycol ethers, because cancel these existing liabilities.

By pre-shredding the plastic parts better manageability and eligibility. The duration of the procedure is also reduced. So it can Regrind continuously in a countercurrent screw, in which grinds in one direction and the medium in Countercurrent is treated.

A particular advantage is achieved when using the solution used a multiple benefit is achieved. The Solution is used for cleaning and / or Sorting the plastic parts or the individual Materials used. A sorting is under Exploitation of the different densities of the separated ones Materials e.g. B. by a swim-sink separation carried out. In the counterflow screw separated material layers from the medium at the same time washed away due to their lower density.

By slightly damaging the over the aluminum Layer of material layers will be Crushing before separation by the medium superfluous. Doing so can easily damage them continuously using rollers or on an assembly line be performed. By foregoing one  Shredding has special advantages. Next the possible reuse of the undestroyed products is the washing and drying effort in contrast to shredded products much lower.

A particular advantage is when punching from achieved plate-shaped plastics, especially when this already freed from layers of material and through that Hot air drying are warmed because of such a homogeneous Granules of the same grain size are obtained and the accumulation of fine fractions is avoided.

Embodiments of the invention are as follows described in more detail.

Optical data carriers such as compact discs consist of Polycarbonate. There is one on one side Aluminum layer through an acrylate lacquer layer is protected. There is printing on this. These compact disks fall in both production and Waste as well as unsaleable residual stocks in large amounts of.

In a flask, three 1 _* 1 cm pieces of a compact disk with 200 ml of 10 wt .-% aqueous sodium hydroxide solution be presented. It is stirred for 10 minutes at a temperature of 80 ° C on a magnetic stirrer. The aluminum layer is dissolved and the bond is released. By pouring through a coarse mesh sieve and then washing with distilled water, the lacquer layers are separated and a pure, high-quality polycarbonate is obtained.

By using ultrasound (30 kHz) at 70 ° C achieved within 3 minutes.

Incident in the manufacture of reflectors for lamps and after painting the aluminum-vapor-coated Plastic parts rejects.  

So reflectors were swiveled with a 5% treated aqueous sodium hydroxide solution. After removing the paint and Aluminum layer, washing with dist. water and then drying in a circulating air cabinet another flawless aluminum vapor deposition carried out.

The procedure described represents a valuable one Contribution to environmental protection through the preservation of a high quality recyclate and the environmental friendliness of Procedure.

Claims (23)

1. A method for separating aluminum layers and any overlying material layers from underlying plastics that are not foils, characterized in that the aluminum layer is brought into contact with a means that detach and / or dissolve the aluminum Layer causes and thus also leads to the separation of all layers above. 2. The method according to claim 1, characterized in that surface and / or under aluminum layers linear layers of aluminum or its Alloys are to be understood which, for. B. by Evaporation or electroplating on the plastic were applied. 3. The method according to claim 1 or 2, characterized in that under layers of material that are on the aluminum Layers can be one or more Layers of e.g. B. paints or printing inks are understand. 4. The method according to any one of claims 1 to 3, characterized in that aqueous and / or alcoholic solutions, which are either alkaline or acidic are. 5. The method according to any one of claims 1 to 4, characterized in that as additives to the agent surfactants or others detergent substances or glycol ethers are used become.   6. The method according to any one of claims 1 to 5, characterized in that the procedure at room temperature or higher Temperature is carried out. 7. The method according to any one of claims 1 to 6, characterized in that the procedure under the influence of Ultrasonic waves, e.g. B. in an ultrasonic bath, is carried out. 8. The method according to any one of claims 1 to 7, characterized in that the aluminum is dissolved in aqueous alkali and the dissolved aluminum as aluminum hydroxide from the Solution fails and the lye does not soak consumed. 9. The method according to any one of claims 1 to 7, characterized in that after the compound separation in the mean at the same time a sorting of the separated material layers of the plastic parts by mechanical processes such as B. Seven or swim-sink separation is carried out. 10. The method according to any one of claims 1 to 9, characterized in that after the composite separation, the plastic parts the means with mechanical processes like sieving be separated and then a rinse of the Plastic parts with acid and / or neutral aqueous solutions takes place.   11. The method according to any one of claims 1 to 10, characterized in that after the composite separation a separation of the separated material layers from the plastic Divide by drying the plastic parts hot air flow carried out by wind sighting becomes. 12. The method according to any one of claims 1 to 11, characterized in that the coated plastic parts before or during the separation can be crushed. 13. The method according to any one of claims 1 to 12, characterized in that the dissolution of the aluminum and thus the separation of the material layers from the plastic part simultaneous mechanical stress such. B. by turbo washing and / or spinning and / or Shredding in a granulator and / or strong Stir is supported. 14. The method according to any one of claims 1 to 13, characterized in that the process in a countercurrent screw with a Grist-like material is carried out, whereby the mean in counterflow the material layers from Plastic separates and at the same time a sorting takes place. 15. The method according to any one of claims 1 to 11, characterized in that the coated plastic parts without Pre-shredding with or without superficial Machining by mechanical methods in the form of Scoring, scratching, piercing, sanding or Brushes are brought into contact with the medium.   16. The method according to claim 15, characterized in that the plastics as a plate-shaped material are available and continuous processing z. B. by going through with needles Rolling is carried out. 17. The method according to claim 15, characterized in that those obtained after separation of the layers Plastic parts can be coated again or find use as a whole. 18. The method according to claim 15, characterized in that the plastic parts in manually or automatically Sieve baskets are sorted so that they face each other not or hardly touch, and then the Sieve baskets pass through the separation medium. 19. The method according to any one of claims 1 to 16 and 18, characterized in that the before, during or after the procedure shredding of the plastic parts by mechanical processes such as grinding, Cutting granulation or punching is carried out so that a granular material is obtained which directly in extruders and injection molding machines can be processed. 20. The method according to claim 19, characterized in that the plastics as a plate-shaped material are present and punching after separating the Layers and after washing with the already pre-dried hot plastics is carried out.   21. The method according to any one of claims 1 to 20, characterized in that separation of material layers such as paints, that are not above aluminum layers, removed by mechanical methods such as grinding become. 22. The method according to any one of claims 1 to 21 except 17, characterized in that separation of material layers such as paints or other solid contaminants from the Plastic melt carried out through melt filter becomes. 23. The method according to any one of claims 1 to 22, characterized in that the separation of aluminum, paint and printing Layers of compact discs and reflectors is carried out.