WO2021121476A1

WO2021121476A1 - Container and method for separating individual plies of a multi-ply composite body

Info

Publication number: WO2021121476A1
Application number: PCT/DE2020/101055
Authority: WO
Inventors: Bernd Robertz
Original assignee: PKG Schürfeld GmbH
Priority date: 2019-12-17
Filing date: 2020-12-14
Publication date: 2021-06-24
Also published as: DE102019134689A1; EP4076953A1

Abstract

The invention relates to a container consisting of a multi-ply bonded composite, wherein adjacent plies consist of the same or different polymers, and optionally at least one of the outer plies is colored. According to the invention, a layer is arranged between adjacent plies, said layer, as a result of its material composition, being released from the adjacent ply or adjacent plies (adhesive failure) or breaking up (cohesive failure) when mechanical, physical, and/or chemical treatments are used. In order to separate individual plies, the composite workpiece is shredded in order to form a granular material with a maximum grain size D₁₀₀ of ≤ 10 mm.

Description

Container and method for separating individual layers of a multilayer

Composite body

The invention relates to a container consisting of a multi-layer, in particular coextruded, materially bonded composite, adjacent layers consisting of the same or different polymers and optionally at least one of the outer layers being colored. The invention also relates to a method for separating individual layers of a multi-layer composite material.

Plastics are indispensable materials for packaging, especially for liquids of different viscosities or solids. Examples of this are plastic bottles made of transparent, white or colored PE or PET, HDPE bottles as squeeze bottles in the cosmetics industry, cans and jars. Transparent bottles or slightly colored bottles for the beverage industry are mostly used as reusable bottles, the product and other manufacturer information often being printed on a label that is either stuck on or, in the embodiment, shrink film. The reusable plastic bottles returned after use are stripped of the label, washed, refilled and labeled before they are returned to the consumer cycle. Disposable plastic containers are first sorted according to the material, then often shredded and sent to a recycling process in order to recover the plastic as a raw material.

Insofar as such plastic bottles consist of a uniform polymer material such as polyethylene, recycling does not cause any major problems because after the material sorting mentioned, no further separation processes of different materials have to be carried out. This also applies if plastic packaging mixtures, which for example consist of PET and PE, have to be separated from one another, because the objects, which each consist of a uniform material, can be subjected to a so-called swim-sink process due to their different densities, in which, for example, the PE due to the low density of 0.92 g / cm ³ to 0.97 g / cm ³ in water floats, while PET sinks with a density of, for example, 1.38 g / cm ³ and can accordingly be easily separated.

More problematic, however, is the recycling of different coextruded plastics, such as multilayer films and containers, as well as coextruded plastics of the same type, but in which only individual layers, usually the outer one, are colored. The remelting of these multi-layered, partially colored plastics means that the previously uncolored plastic is now also colored, i.e. is "contaminated" by the dye.

WO 2018/055088 A1 describes a method for reversible coloring of polymer material with a disperse dye. The polymer material contains an additive for at least one dye. The polymer material is heated to an activation temperature below the softening temperature and brought into contact with an aqueous dye dispersion heated to a similar temperature, the dyes migrating into the polymer material and being embedded in the additive. Mixtures can be used as additive, for example, which consist of a first terpolymer, composed of ethylene, acrylic or methacrylic esters and maleic anhydride with an anhydride content of at least 2%, and a second terpolymer made of ethylene, acrylic or methacrylic ester and glycidyl (meth) acrylate a glycidyl content of at least 7% and mixtures thereof, and an amine-terminated polyamide or polyether amide.

Such additives offer the possibility of allowing dyes to diffuse only in a thin area close to the surface through migration.

A potential decolorization of a multi-layer plastic consisting of a first colored layer (skin), which contains the above-mentioned additive and a second layer (body) made of the same plastic but without the dye-affine additive and thus without the dye, leads to a dramatic loss of efficiency in decolorizing systems , because in these processes, instead of just the colored layer, the entire plastic structure has to be subjected to the process. A possible Separation of the colored layer (skin) from the non-colored layer (body) would lead to a considerable increase in efficiency (higher throughput).

According to the prior art, multilayer films or containers are also known in which the individual layers are made of different materials, in particular different polymers, in particular from the group of PE, PET, PA and / or PP. The individual layers, each consisting of a single polymer and, if necessary, other functional additives such as UV and oxidation stabilizers, antistatic agents or inorganic fillers, are processed into a material bond as part of a coextrusion. In order to ensure sufficient adhesion, so-called binding layers are often co-extruded. According to the prior art, for example, multilayer composite materials are known in which the layers of polyamide, ethylene-vinyl alcohol copolymer (EVOH) and polyethylene are connected to one another by adhesive layers (so-called tie-layers), for example made of maleic anhydride-grafted polyethylene, which are connected to one another between the PA and EVOH or between EVOH and PE are arranged. Such or similar layer structures are extruded into films with a sufficient thickness and, for example, deep-drawn into bowls, cups, lids or other bodies or extruded as a hose and finally blown into hollow bodies such as bottles or containers.

DE 19831 118 B4 describes a method for separating the components of a multi-layer material, which comprises at least one layer made of a basic raw material (e.g. from one or more polyolefins, selected from homopolymers and copolymers of ethylene or propylene), and a layer made of a second plastic, for example a barrier polymer such as a polyamide or a copolymer of ethylene and vinyl alcohol, which are connected to one another by a layer of an adhesive which can consist, for example, of a polyolefin grafted with maleic anhydride. This composite material is heated to a temperature between the crystallization temperature of the second plastic (barrier polymer) Tc and Tc-20 ° C, after which the material is comminuted by subjecting it to a shear stress approximately at subjected to the same temperature, thereby causing delamination and converting the material into particles of smaller dimensions of two types, one of the particles being composed essentially of the former plastic (polyolefin) and the other particles being composed essentially of the second plastic (barrier polymer ) and the adhesive are built up. Subsequently, all particles are to be separated by electrostatic separation, after which the particles to be separated are electrically charged by being brought into contact with a mobile device, which essentially consists of a plastic analogous to the adhesive, at least on the surface. A concrete example describes the separation of a 5-layer fuel tank of the type PEHD / PE-gMSA / EVOH / PE-g-MSA / PEHD.

Also known from the prior art is the separate extrusion of two foils and a subsequent lamination of these foils by means of adhesives. This method is often used when one of the foils is printed and the print is to be laminated between two foils in order to avoid direct contact with the printing ink when it comes into contact with the outside, as well as sufficient scratch resistance or special effects such as an optical gloss should be achieved. Efforts to date have essentially consisted of creating a durable film composite including printed intermediate layers. However, such an objective is in contrast to the recyclability of plastics if the individual layers of different polymers cannot be easily separated.

In principle, the selective dissolution of individual types of polymer or the adhesive is conceivable by using special solvents that are used under certain temperatures and pressure to dissolve an individual polymer in the sense of "dissolving", after which the dissolved polymer is removed and then, if necessary, a new solvent is used to dissolve out another polymer component at a higher temperature and pressure. However, such a method has the disadvantage that the dissolved polymers are not chemically pure and the use of organic solvents, even when recovering and processing them, contradicts the basic idea of sustainability. Well-known processes are the PureCycle process developed by Procter & Gamble or the CreaSolv process developed by the Fraunhofer Institute.

The object of the present invention is to create a container of the type mentioned at the outset in which there is an improved separation of the individual layers in the context of recycling. In particular, the film or the container should be designed in such a way that, by recycling, different layers of polymers can be separated cleanly, essentially without the use of exclusively organic solvents, and any colored layers can be cleanly separated from other layers that are not "contaminated" with a dye . A separation method should also be specified.

This object is achieved by a container according to claim 1. Further developments of the container are described in the subclaims. According to the invention, a layer is arranged between adjacent layers made of different polymers, in particular between an outer colored layer and the adjacent layer, which, due to its material composition, becomes detached from the adjacent layer or layers when physical and / or chemical and / or mechanical treatment is used . Instead of the adhesive layers primarily used as intermediate layers according to the prior art, separating layers are deliberately incorporated within the scope of the present invention, which on the one hand ensure sufficient adhesion of the layers in the application, but on the other hand ensure that the individual layers are separated after use. If the outer layer or layers of a container are colored and the layers in between are dye-free, it can be advantageous if the separating layer remains on the colored layer when the layers are separated due to different bonding effects and separated from a separation process, e.g. by sinking deposition or floating becomes. In the context of the present invention, in particular, the separation of colored layers (plies) from non-colored layers (plies) can take place, whereby cross-contamination of the uncolored plastics in a decolorizing bath can be avoided. A plastic discoloration that is not 100% successful cannot therefore lead to contamination of an uncolored plastic when the plastic is melted and regranulated.

When the individual layers are separated, the accumulation of foreign substances in the entire plastic mass is avoided, which means that multi-layer plastics of different plastics or plastics with different additives can be recycled by separating the individual fractions with a high degree of purity. Otherwise occurring interactions and reciprocal reactions of different contaminants can also be avoided. Chemical, physical and mechanical treatments are understood to mean all processes that are suitable or suitable for helping to improve the separation of the layers containing valuable substances which are to be recycled. From a mechanical point of view, this can be, for example, treatments by shearing, stretching, bending and / or impact, from a physical point of view, treatments such as temperature changes due to heating or cooling, with and without pressure change, irradiation, in particular with IR, UV, beta or gamma Radiation, special treatments of the separating layers to create layer structures, porosity, embedded particles as spacers (D (particles)> D (separating layer) or particles with D (particles) <D (separating layer), which only occur in the recycling process, e.g. through Contact with water swell and greatly increase its diameter) or the like. Chemical treatments are, for example, the use of water, steam, other not exclusively organic solvents or their vapors, bases, acids, plasticizers, complexing agents, salts, surfactants, oxidizing or reducing agents, in particular in a solution at different temperatures and / or pressures, as well the addition of reactants (e.g. citric acid and sodium hydrogen carbonate), which thereby ensure the adhesion of the layers to one another in particular increase the separating layer and / or the solubility or swellability to reduce the mechanical strength of the separating layer in the surrounding medium (reduction of the adhesion and / or cohesion of the separating layer).

An embrittlement of individual layers is also conceivable, e.g. through cooling or the addition of additives to the separating layer, which through irradiation lead to chain cleavage and thus to polymer degradation, which in turn reduces the adhesion. An example here is the degradation of polypropylene by exposure to beta or gamma radiation.

The separation layers can also be selected in a targeted manner by using separation layers which have a lower or a significantly higher melting temperature compared to the melting temperature which the respective polymers of the different layers have. The same applies from a chemical point of view with regard to the selection of certain non-exclusively organic solvents, bases or acids which, if necessary after perforation of the outer layers or the adjacent layer, only attack the separating layer and enter into reactions with these. Targeted melting of the separating layer is also possible, which is reinforced by radiation agents and correspondingly suitable additives, i.e. additives absorbing in the wavelength range of the radiation agent, diffusion of separating agents or selective pyrolysis. The core idea of the present invention is that the action of mechanical, physical and / or chemical treatments on the separating layers brings about a separation of the individual layers of uniform or different polymers, which can then be further processed separately, in particular recycled.

In summary, this means: The separating force acting on the multilayer object, in particular the separating layer, as the sum of mechanical, physical and chemical force, is greater than the adhesion of the layers to one another and / or the cohesion of a single or multiple layers. The separating layer can also be selected in such a way that it simultaneously forms a barrier layer for migrating dyes, so that when the container is colored, dyes only diffuse in layers beyond the barrier layer, so that after separation of the colored or an insufficiently bleached outer layer, "color-free" layers can be obtained as a pure recyclable product. For example, an inner layer made of pure PE or PP can form a barrier for dyes, which preferably have an affinity for polar plastics.

The following substances are preferably used as examples of a separating layer between two layers, of which the separating layer consists or which the separating layer essentially contains (the list of possibilities is only for clarification and does not claim to be exhaustive):

Wax, silicone, water-swellable or water-soluble polymers, demolition additives (i.e. substances that swell strongly in certain media), substances with a melting point between 50 ° C and 120 ° C; substances that can be heated by UV or IR radiation; Substances which are soluble or swellable in solvents or acids or bases or mixtures thereof and in which the polymer layers are resistant; from the polymer layers in terms of the coefficient of thermal expansion significantly different substances; Substances that become brittle under the influence of temperature changes, in particular cooling or under beta, gamma, X-ray, UV or IR radiation; Substances that become detached from polymer layers due to reactions of functional groups due to a change in mechanical properties, in particular strength, such as anhydrides, amines, bases and acids or polyelectrolytes.

The water-soluble or water-swellable polymers include, inter alia, uncrosslinked or weakly to strongly crosslinked polyvinyl alcohols and its copolymers and terpolymer polymers such as. B. ethylene-vinyl alcohol copolymers with different degrees of saponification, butanediol-vinyl alcohol copolymers, polyacrylic acid and its copolymers, especially in an alkaline medium, polymethacrylic acid and its copolymers, especially in an alkaline medium, other polymerizable acids and their salts, in particular maleic, fumaric, itaconic, vinylsulphonic or 2-acrylamido-2-methylpropanesulphonic acid and their copolymers. Furthermore, hydroxyl-containing esters of polymerizable acids, in particular the flydroxyethyl and hydroxypropyl esters of acrylic and methacrylic acid, can be used, as well as amino-containing and ammonium-containing esters and amides of polymerizable acids, such as the dialkylamino esters, in particular the dimethyl and diethylaminoalkyl esters of acrylic and methacrylic acid, as well as the trimethyl and triethylammonium alkyl esters and the corresponding amides. Further swellable hydrogel-forming polymers are, in particular, polymers made from (co) polymerized hydrophilic monomers, graft (co) polymers of one or more hydrophilic monomers on a suitable graft base, cross-linked cellulose or starch ethers, cross-linked carboxymethyl cellulose, partially cross-linked polyalkylene oxide or natural products swellable in aqueous liquids such as guar derivatives.

A further preferred separation layer configuration can be achieved through the use of explosive additives (disintegration accelerators) made from starch, cellulose and its cellulose derivatives (e.g. based on methyl cellulose (MC), microcrystalline cellulose (MCC), hydroxypropylmethyl cellulose (HPMC), methylhydroxyethyl cellulose (MHEC), Hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), sodium carboxymethyl cellulose (NaCMC)), carboxymethyl cellulose, cross carmellose, cross carmellose sodium, alginic acids, dextrans and cross-linked polyvinylpyrrolidones, as well as weakly to strongly cross-linked polyvinyl alcohol and its copolymers such. B. ethylene vinyl alcohol copolymers with different degrees of saponification, gas-evolving substance mixtures z. B. sodium carbonate and citric or tartaric acid, coprocessed polysaccharide, polyacrylic acid monopolymers, polyacrylamide monopolymers, polyacrylic acid-polyacrylamide copolymers and mixtures thereof. The latter substances are insoluble in water due to their degree of crosslinking and / or a correspondingly high degree of polymerization, but they are very swellable. The swollen polymers point to one has a lower mechanical strength (than in the unswollen state) and increases the distance between the layers to be separated, so that the penetration of the release agent is promoted.

According to a further embodiment of the invention, it is also possible to glue adjacent boundary layers selectively, preferably by means of laser welding. The prerequisite for this is that one of the layers, e.g. due to an opaque design or material inclusions, which are suitable for absorbing the energy introduced by the laser beam, is present. Irradiation by means of a laser, e.g. an Nd: YAG laser, enables spatially limited, punctual material heating, which leads to a material bond when it cools down. The limitation of the connection points to a few points facilitates the mechanical separation of two layers, since only the few weld points have to be broken, which in certain circumstances can already be achieved by mechanical crushing (shredding). When separating different materials, particles of the other material that are still adhering do not matter.

WO 2018/055088 A1 discloses a method for the reversible coloring of polymers or polymer layers by immersion in a heated aqueous dye bath containing a disperse dye. By changing the ambient conditions, the dye can be removed again from the polymers by migration. The layer which can be colored in this way contains a binder additive for at least one dye, the binder additive consisting of

- A first terpolymer of ethylene, acrylic or methacrylic ester and maleic anhydride with a maleic anhydride content of at least 2% by weight and

- a second terpolymer made from ethylene, acrylic or methacrylic ester and glycidyl methacrylate with a glycidyl content of at least 7%,

- or mixtures thereof, in connection with an amine-terminated polyamide or polyether amide. This outer colored layer is followed by the separating layer, followed by a layer made of a recyclable polyolefin. The colored layer with the separating layer is preferably separated and removed from the process by means of methods known in principle from the prior art, so that the remaining polyolefin layer can be separated as a pure layer and can be reprocessed.

To separate the individual layers of the films or containers according to the invention, it is proposed that the composite workpiece be shredded into granules with a maximum grain size D100 ^ 10 mm, preferably <5 mm, further preferably <3 mm and further preferably <1 mm in order to achieve the effective To enlarge the surface for a chemical treatment, which is preferably carried out in an alkaline manner.

The idea behind this process is essentially based on the fact that the possible separation points for the films to be separated can be reached more easily. By shredding into small particles, the attack surface for separating the layers is considerably enlarged. In the case of plastic films or plastic containers comminuted in this way, a chemical treatment of a separating layer lying between two further layers generally only takes place over or on the cut edge. The total length of the cutting edge becomes larger in relation to the surface of the shredded plastic, the smaller the area of the shredded plastic. Therefore, the grain size of a granulate exposed to the separating forces should be as small as possible. Shredding corresponds to a mechanical treatment of the films or containers according to the invention, which can at least lead to “fatigue” of the separating layer and thus better separability.

Preferably, different grain size fractions z. B. separated by means of a sieve and the individual fractions are subjected to a separation process to ensure the separation of the layers and the increase in effectiveness. Furthermore, the grain size distribution of the fractions is preferably chosen to be narrow, in particular such that the deviation from a mean Wherein D10 and D90 respectively designate particle size Dm to D10 to Dm and / or D90 to D _m at most 1 mm is the diameter at which 10% and 90% of the granules are below the value D10 and D90. The index "m" stands for the mean grain size, which in a specific embodiment, 10 mm, 5 mm,

3 mm and 1 mm, so that, for example, the grain size distribution 0 mm to 2 mm, 2 mm to 4 mm, 4 mm to 6 mm and higher fractions between 6 mm and 11 mm can be obtained by sieving. The different fractions can be “washed” for different lengths of time in suitable baths, especially in order to wash out the color components from the outermost layer. If the treatment is continued or renewed, the individual layers can be separated using an aqueous alkaline heat bath. In this way it is possible to optimally determine the treatment duration for the individual fractions.

According to a further embodiment of the invention, the alkaline treatment is carried out in stages at different temperatures between 40 ° C and 80 ° C, preferably between 60 ° C and 80 ° C, with different adhesion promoters being dissolved per separation stage in order to obtain different fractions for separate further negotiations. For example, thermoplastic polyvinyl alcohols are suitable for this, such as the Mowiflex M05 (solvent temperature 50 ° C.) or Mowiflex C15 (solvent temperature 70 ° C.) known from the prior art.

Furthermore, the present invention is explained using specific exemplary embodiments:

Example 1:

A 3-layer container A // B // A ((// = identification of the individual layers) is produced on a blow molding machine by coextruding (A) polyethylene LyondellBasell / Hostalen ACP 5531 B and (B) polyvinyl alcohol Kuraray / Mowiflex C 17 with layer thicknesses of 250 pm for A and 25 pm for B. The individual layers adhere sufficiently to one another due to the 3D shape of the container. The container is shredded and sieved using a standard size 12 sieve and separated into individual size fractions. The mean size of the plastic flakes of the two fractions is <6 mm or 6 - 8 mm. In some of the flakes, the layers are already separated by the mechanical action during shredding.

Both fractions are placed in a water bath at 75 ° C., 2% NaOFI, the concentration of the flakes in the washing solution is 5% by weight. The layers of flakes separate after a short time, the polyethylene floats while the Mowiflex dissolves. The layers in the fraction with the smaller flakes detach or dissolve more quickly than in the fraction with the larger flakes.

The flakes are sieved and dried. A thickness measurement and a GPC of the remaining plastic parts show that the Mowiflex has completely detached from the polyethylene.

Example 2:

The experiment from Example 1 is repeated, with a further layer C each consisting of a mixture of (C) polyethylene Hostalen ACP 5531 B and the adhesion promoter Licocene PE MA 4351 (Clariant, PE graft) between the layers A // B // A -MSA) is arranged so that a layer structure according to A // C // B // C // A results. The layer thicknesses are A = 250 pm, B = 25 pm, the thicknesses of the adhesion promoter layers C are each 5 pm.

As in Example 1, the container is shredded and sieved using a commercially available 12-piece sieve and separated into individual size fractions. The mean size of the plastic flakes of the two fractions is <6 mm or 6 - 8 mm. In contrast to Example 1, no layer separation is observed due to the purely mechanical action during shredding.

Both fractions are placed in a drum in a water bath at 75 ° C., 2% NaOH and agitated for about 30 minutes. The concentration of the flakes in the washing solution is 25% by weight (based on the amount of water). To improve the mechanical effect, a further 25% by weight of ceramic beads D = 10 mm are added added The layers of the flakes separate after a short time, despite the adhesive layers, the Mowiflex dissolves.

The last smaller gel particles, presumably caused by the crosslinking of the adhesion promoter layer through the addition of Licocene PE MA 4351, are separated off when the plastic flakes are filtered off and washed. A thickness measurement after drying and a GPC recording show that the Mowiflex has completely detached from the polyethylene.

Example 3:

A 3-layer container A // B // A ((// = identification of the individual layers) is produced on a blow molding machine by coextruding (A) polypropylene Borealis / RB206MO and (B) a mixture of 97% acrylic acid-modified polypropylene Addivant / Polybond 1001N and 3% hydroxyethyl cellulose Ashland Natrosol ™ 250 HX with layer thicknesses of 250pm for A and 25pm for B.

The container is shredded and sieved using a standard size 12 sieve and separated into individual size fractions. The mean size of the plastic flakes of the two fractions is <6 mm or 6 - 8 mm. In some of the flakes, the layers are already separated by the mechanical action during shredding.

Both fractions are placed in a water bath at 75 ° C., 2% NaOH, with vigorous stirring; the concentration of the flakes in the washing solution is 5% by weight. Immediately after entry into the alkaline bath, there is a clear increase in volume of the flakes, followed by a rapid separation of the layers. The polypropylene floats while the mixture of layer C z. T. goes into solution, z. T. floats as gel particles in the solution. Here, too, the layers in the fraction with the smaller flakes detach or dissolve more quickly than in the fraction with the larger flakes.

The flakes are sieved and dried. A thickness measurement and GPC of the remaining plastic parts show a pure polypropylene. Example 4:

A 3-layer container A // B // A ((// = identification of the individual layers) is produced on a blow molding machine by coextruding (A) polyethylene LyondellBasell / Hostalen ACP 5531 and (B) a mixture of 99% ethylene Acrylic acid copolymer SK Global Chemical PRIMACOR ™ 5980I and 1% of a PE masterbatch consisting of 37% monosodium citrate, 22.5% sodium hydrogen carbonate, 0.5% glycero monostearate filled up to 100% with polyethylene LyondellBasell / Hostalen ACP 5531 with layer thicknesses of 250 μm each for A and 25pm for B.

Both fractions are placed in a water bath at 75 ° C. with vigorous stirring; the concentration of the flakes in the washing solution is 5% by weight. Immediately after entry into the water bath, gas bubbles form between the layers and, as a result, the flakes increase in volume, followed by a rapid separation of the layers. The polyethylene floats while the mixture of layer C z. T. goes into solution, z. T. floats as gel particles in the solution. Here, too, the layers in the fraction with the smaller flakes detach or dissolve more quickly than in the fraction with the larger flakes.

The flakes are sieved and dried. A thickness measurement and a GPC of the remaining plastic parts show a pure polyethylene.

Example 5:

As in Example 1, but using Mitsubishi BVE 8049P butanediol-vinyl alcohol copolymer instead of Kuraray / Mowiflex C 17 polyvinyl alcohol. The layers separate more quickly than in Example 1, and a pure polyethylene is obtained. Example 6:

When choosing a 5-layer structure A // C // B // C // A, Kuraray Mowiflex C 17 (250 pm) and polyethylene Hostalen ACP 5531 (25 pm) for layer (C) are used as the outer layers (A) . The middle layer (separating layer (B)) consists of Mowiflex H 15 or a material that is soluble in hot water (75 ° C).

Example 7:

The present invention also includes those embodiments in which two layers such. B. HDPE and PA lie directly next to each other in a composite material, which have little or no adhesion to each other. For example, a layer system HDPE // PA // PA / PE can be selected (// = identification of the individual layers; PA / PE = blend of the two polymers PA6 and HDPE). The HDPE layer can be separated from the neighboring PA layer by shredding. In this case, the aforementioned layers can also be separated without washing solutions or other chemical aids.

Example 8

An (A) 200pm cast polyamide film (PA 6) from mf-folien GmbH and a (B) 200pm PET-G film from Folienwerke Wolfen are (C) using Arkema / Platamid HX2544 to form a film composite A // B // C laminated together and wound up. 20% by weight of a core-shell product containing a mineral oil as core has been incorporated into the platamide. The film composite is stored for 48 hours at room temperature so that the laminating adhesive has sufficient time to crystallize and a solid bond results.

The composite is unrolled and passed at 3 m / min through a pair of heated steel rollers imitating a calender at 150 ° C. and 3 bar contact pressure and then held at 100 ° C. for about 1 min, so that the shell of the core-shell products bursts and the mineral oil comes out. The film composite is stored again for 48 hours at room temperature, so that, on the one hand, the laminating adhesive has sufficient time to crystallize and a solid bond results. The adhesion of samples (1) of the original assembly (before the destruction of the core-shell products) and samples (2) after the thermal treatment (after the destruction of the core-shell products) are tested on a tensile testing machine from Zwick / Roell tested. It can be seen that the bond strength of sample 1 to sample 2 has decreased by more than 1/3.

Example 9

A multi-layer container A // D // B // D // C (from inside to outside; // = labeling of the individual layers) is produced on a blow molding machine by coextruding (A) polyethylene LyondellBasell / Hostalen ACP 5531 B,

(B) Kuraray / Mowiflex C 17 polyvinyl alcohol, (C) a mixture of LyondellBasell / Hostalen ACP 5531 B polyethylene (90%), a first terpolymer (3%) consisting of ethylene (82% by weight), methacrylic acid ester (15% by weight). %) and maleic anhydride (3% by weight) and a second terpolymer (2% by weight) made of ethylene (85% by weight), methacrylic acid ester (10%) and glycidyl (meth) acrylate (7% by weight) and an amine-terminated polyether amide (5% by weight) and (D) as an adhesion promoter layer a mixture of polyethylene Hostalen ACP 5531 B and the adhesion promoter Licocene PE MA 4351 (Clariant, PEpfropf-MSA) with layer thicknesses of 700pm for A, 70pm for C, 25pm for B and 5pm for D. The container is colored blue in an immersion bath as described in WO 2018/055088 A1. As in Example 1, the container is shredded and sieved using a commercially available 12-gauge sieve and separated into individual size fractions. The mean size of the plastic flakes of the two fractions is <6 mm or 6 - 8 mm. In contrast to Example 1, no layer separation is observed due to the purely mechanical action during shredding. Both fractions are placed in a drum in a water bath of 75 ° C., 2% NaOH and 0.2% Oakite RC 7A (mixture of nonionic and anionic surfactants) and agitated for about 30 minutes. The concentration of the flakes in the washing solution is 10% by weight (based on the amount of water). To improve the mechanical effect, a further 10% by weight of ceramic beads D = 10 mm are added. The layers of the flakes separate after a short time, and the Mowiflex dissolves in spite of the adhesion promoter layers. Last smaller gel particles, presumably caused by the crosslinking of the Adhesion promoter layer through the addition of Licocene PE MA 4351 are removed during the filtering and washing of the plastic flakes. The colorless and colored flakes are separated using a process common in recycling processes. For this purpose, these are placed on a conveyor belt. The flakes are differentiated by means of a camera system for the detection of colors in the wavelength range 300 - 700 nm, the flakes are separated by compressed air nozzles, in which the identified colored flakes are specifically blown out. The colored flakes are completely decolorized for 30 minutes in an aqueous solution containing 4 g / L NaOH, 5 g / L formamidinesulfonic acid (e.g. Redulit F from CHT) and 4 mL of a mixture of aromatic carboxylic acid esters such as benzyl benzoate (decolorizing accelerator) and can the fraction of the uncolored flakes are fed back. A thickness measurement after drying and a GPC recording show that the Mowiflex has completely detached from the polyethylene.

Claims

Expectations

1. Container consisting of a multi-layer, in particular coextruded, cohesive composite, with adjacent layers consisting essentially of the same or different polymers and optionally one of the outer layers being colored, characterized in that between adjacent layers, in particular between an outer one, if necessary . The colored layer and the layer adjacent to it a separating layer is arranged which, due to its material composition, becomes detached from the adjacent layer or layers (adhesion break) or is separated (cohesion break) when mechanical, physical and / or chemical treatments are used.

2. Container according to claim 1, characterized in that the separating layer between two layers consists of or contains at least one of the following substances:

Wax, silicone, water-swellable or water-soluble polymers, demolition additives, substances with a melting point between 50 ° C and 120 ° C; substances that can be heated by UV or IR radiation; Substances which dissolve in solvents or acids or bases or mixtures thereof and in which polymer layers are resistant; from the polymer layers in terms of the coefficient of thermal expansion significantly different substances; Substances that become brittle under the influence of temperature changes, in particular cooling or under beta, gamma, X-ray, UV or IR radiation; Substances that become detached from polymer layers due to reactions of functional groups due to a change in mechanical properties, in particular strength, such as anhydrides, amines, bases and acids or polyelectrolytes.

3. Container according to one of claims 1 or 2, characterized in that the explosive additives are not exclusively made in water or mixtures organic solvents consist of substances that swell strongly, preferably starch, cellulose derivatives, alginic acids, dextrans and cross-linked polyvinylpyrrolidones, gas-evolving substance mixtures, in particular coprocessed polysaccharide, polyacrylic acid monopolymers, polyacrylamide monopolymers, polyacrylic acid-polyacrylamide copolymers and mixtures thereof.

4. A container consisting of a multi-layer, in particular coextruded, cohesive composite, with adjacent layers consisting essentially of the same or different polymers and, if necessary, one of the outer layers being colored, characterized in that the adjacent boundary layers are adhesively bonded at points, preferably by means of laser welding are.

5. A method for separating the individual layers of a multi-layer composite workpiece according to one of claims 1 to 4, characterized in that the composite workpiece is formed into granules with a maximum grain size D100 ^ 10 mm, preferably <5 mm, further preferably <3 mm and furthermore preferably <1 mm is shredded in order to enlarge the effective surface for a chemical treatment which is carried out under alkaline conditions.

6. The method according to claim 5, characterized in that different grain size fractions z. B. be separated by means of a sieve, and the individual fractions are separated and subjected to the separation process to ensure the separation of the Lagn and increase the effectiveness.

7. The method according to claim 6, characterized in that the grain size distribution of the fractions is selected to be narrow, preferably such that the deviation from a mean grain size Dm to D10 to Dm and / or Dgo to Dm is a maximum of 1 mm, D10 and Dgo respectively the Name diameters where 10% or 90% of the granulate is below the values D10 and D90.

8. The method according to any one of claims 5 to 7, characterized in that the alkaline treatment is carried out in stages at different temperatures between 40 ° C and 80 ° C, different adhesion promoters being dissolved per separation stage in order to obtain different fractions for separate further treatment.