Machine and plant manufacturers used the trade show to demonstrate the flexibility and efficiency of their systems. They follow different philosophies, with the result that a variety of new developments and improvements have emerged. 

Aufbereitungsmaschinen

Schmelzefilter

Mühlen

Compoundieren

Compounding: Mastering a Variety of Tasks 

Both the quantity of recycled plastics waste and of processed recyclates is continually increasing. However, there are still difficulties with the quality of the recycled plastics, which are impeding replacement of virgin material. In recent years, machinery manufacturers and plastics producers have introduced various further developments that improve the properties of recyclates as well as eliminate unpleasant odors and contaminants.

Plastics recycling is a laborious process. For the recycled material to have the necessary quality, it must first be sorted into the different plastics

Overcoming Difficulties in Plastics Recycling

Streifinger, Florian

Recycling

Umweltmanagement

Extruder

Kunststoffverarbeitung: Maschinen und Komponenten

Extrusionsanlagen

Trockner

Kunststoff-Aufbereitung

Waschen und Entfetten

Kunststoffverarbeitung: Verfahren

Trockner, Granulat-

Sortierer

Kunststoff-Recycling

Additive

Kunststoff Werkstoffe

Inspektion, Analyse und Sortierung von Rohmaterial

QualitÃ¤tssicherung

QualitÃ¤tssicherung Kunststoff

The Long Road to a Circular Economy

The manufacturers of machines and systems for plastics compounding are expanding proven series with new sizes and optimizing existing technology. Their main focus is on scale-ups between the systems. Despite highly customized special solutions, modular design enables integration into existing system technology.

Fast Adaptation of System Technology through Modular Design and  High System Efficiency

Wiederaufbereitung

The Formulation Is Not Everything

Compounding engineering focuses on rendering the compounding process more economical. Various approaches are presented for improving the economics, such as the use of more energy-efficient equipment, greater system availability and enhanced throughput. 

Mischer

Extrusion

Compounding, Recycling: Efficiency as Benchmark 

According to the manufacture, the cascade extrusion process from KraussMaffei Berstorff GmbH, Hanover, Germany, PE and PP wastes, but also recyclates of other polymers, can be reprocessed into high-quality recompounds. For this process, two process steps are connected directly in series. The first extruder feeds the washed and sorted recyclate, optionally with prior size reduction or agglomeration, melts it, homogenizes it and degases the melt. Fine filtration at the end of the process unit removes the last contaminants. This treatment may optionally be carried out on a single-screw or twin-screw extruder. Then a pump doses the melt into the second conventional compounding extruder, which besides gravimetric dosing units for the components, also has side-feeding devices and a further degassing unit. Thus, all the ancillary units are present for metering fillers and reinforcing agents, through additives and pigments, but also virgin material, and thus to manufacturing individual compounds. 

KraussMaffei Berstorff 

Industrie 4.0

Cascade Compounding Line 

This subject area covers a whole swath of technologies, with many new developments and improvements being introduced to meet ever-changing market needs. 

Warmformen / Thermoformen

Compounding, Extruding, Thermoforming: Still Room for Improvement 

At this year’s Fakuma trade show, developments and improvement in the area of recycling dominate the picture of engineering and plant construction companies. The emphasis is on detailed solutions to make recycling more efficient and economic.  

From Extrusion Compounding and Recycling up to Thermoforming 

Druck- / Kraftsensoren

The Growing Importance of Recycling Technologies 

Manufacturers of plastics compounding machinery and plants are increasingly offering tailored systems for recycling plastics. Recycling is thus gaining increased acceptance and importance thanks to optimizations in processes.  

Compounders Are Showing Increased Interest in Recyclate 

Complete One-Stop Systems 

The core product of the extrusion machine maker MAS Maschinen- und Anlagenbau Schulz GmbH, Pucking, Austria, is the conical twin-screw extruder with co-rotating screws, which, according to the manufacturer, offers gentle plastication together with good feed characteristics. The third generation is now available in six different sizes with an output range from 10 kg/h to over 2000 kg/h. The most important technical development is the segmented cylinder design, made up of several subsections. As an alternative to exchanging a complete cylinder, it permits individual abrasion-damaged cylinder sections to be exchanged. In addition, MAS is expanding its portfolio with the MAS 24 laboratory extruder, which was developed for plastic manufacturers and compounds to develop formulations under practical conditions and produce them in small amounts. 

MAS 

New Extruder and Melt Filters 

From a technical standpoint the product with which Ettlinger Kunststoffmaschinen GmbH in Königsbrunn, Germany, grabbed our attention is not brand new. It is a melt filter with a cylindrical screen that was developed in 2003 and up until now no more than ten units a year have been sold really as a niche product. However, in the last financial year sales tripled. 

Melt Filter: High Efficiency Drum 

Enhancing mixed bottle flakes by turning them into extrudable recycled crystalline polyethylene terephthalate (rCPET) was the goal of a joint development project looking to close the gap in the PET recycling system. By successfully producing a sheet made from recycled material suitable for high-quality applications such as thermoformed food trays, Gneuss, Sukano and Illig have demonstrated that this approach is indeed possible.

Thermally stable rCPET food trays made from multicolor APET bottle flakes

Upcycling of Mixed APET Bottle Flakes into Thermally Stable rCPET Food Trays

Polybutylenterephthalat

Thermoplaste

Farbstoffe und Pigmente

Anlagen Lebensmittel

Anlagen für die Additive Fertigung

Anlagen Additive Fertigung / 3D-Druck, andere

Filteranlagen

Farbstoffe

Flakes

Kunststoff-Rezyklat

PET: From A to C

With a newly developed process from Entex it was possible to compound an injection grade compound of PLA with a 50 % wood flour content.

The PLA compound with 50 % wood flour content was successfully produced on Entex’s planetary roller extruder

16:9

Compounding PLA Formulations with a 50 % Wood Flour Content, without Premixing

Compound

Biokunststoffe

Kunststoff

Bauwesen

Baustoffe

Direct to Highly Filled Bioplastics

Cutting, homogenizing, heating, drying, compacting, buffering and dosing in a single step – this is the performance range of the cutter/compactor as a preparatory stage for the extruder. Previously the material inside the cutter/compactor turned in the same direction as the extruder. An Austrian recycling specialist has now put this principle “into reverse” and changed the rotating direction of the plastic material inside the cutter/compactor so it is opposite to the extruder’s flow direction. This means that the extruder is filled virtually pressure-free, never overfilled and thus better to control as a result. 

Recycling: Counter Current Principle Improves Productivity 

At K2013, among machine and plant manufacturers, the picture was dominated by improvements of existing technologies and detail solutions. However, some genuine new developments were also presented. The focus continues to be on improving the efficiency and flexibility of compounding machines and systems. 

Trend Report: The Devil Is in the Detail 

In the manufacture of semi-finished products such as fibers or films, waste that can be recycled and reused as a raw material is repeatedly produced along the entire production chain. The recycling of PET is a particular challenge to the plant construction because of the hydrolytic polymer degradation. 

Modular Concept for Industrial Waste Offers Flexible Solutions 

Polyethylenterephthalat

PET Recycling 

The Technology to Close the Plastic Cycle Exists

As expected, the K 2019 displayed a wide range of machine technology and complete system solutions for plastics recycling. At least since the trade fair in Düsseldorf, Germany, it has become obvious that industry today can offer solutions for closing the plastic cycle.

With their unique combination of low weight, longevity and broadly adjustable property spectrum, plastics are the key to future-oriented applications in many application areas. Without plastics, for example, the implementation of e-mobility would be difficult to imagine. Nevertheless, most plastic products have only one product life cycle.  In 2017, according to PlasticsEurope, 64.4 million t of plastic were produced in Europe (EU28+NO/CH).

The largest consumer sector for plastics is the packaging sector with a share of 39.7 %. In particular, plastic is regarded by the consumer as a low-quality product and ideally ends up in the yellow bag after its use and not in the environment.

In 2016, for the first time in Europe, more plastic waste was recycled (31.1 %) than landfilled (27.3 %). However, the largest share is still the thermal recovery in the form of energy recovery with 41.6 %. In particular, the increasing global pollution of the environment and the oceans makes calls for alternatives such as glass, aluminum or paper, which, however, do not always make sense from an ecological point of view. This is why the challenges in the plastic product life cycle and littering have to be solved in order to exploit the full potential of plastics in a closed cycle and a resource-efficient economy. Not only does the recycling rate have to rise. It is also important that plastics are separated according to type and regranulates are produced in consistently high quality. Plastic recycling can therefore be subdivided into different core issues: sorted separation of plastics, cleaning and comminution of plastic material streams and the processing of plastic waste into high-quality regranulates.

Sensor Technology for  Detecting Plastics

The central point in the sorted separation of the plastic material streams is the recognition of the plastic type with the aid of sensors. State of the art and the most common is near infrared spectroscopy (NIR) for the separation of material flows. The plastic waste on the conveyor belt is irradiated with a short-wave infrared spectrum of 780 nm to 2.4 μm. Part of this IR radiation is absorbed, transmitted and reflected by the plastic sample. In the NIR technique, the reflected infrared spectrum is evaluated. Each plastic has a characteristic spectrum for identification. However, the filler soot, which absorbs a large part of the radiation, complicates the measurement. On the other hand, classification problems arise through multilayer plastic products or through the scanning of sleeves.

Tomra Sorting GmbH from Mühlheim-Kärlich, Germany, is trying to improve its NIR technology using artificial intelligence techniques. The Gain deep learning software can detect and classify objects with a specific shape or texture as an add-on to Autosort sorting systems. As a result, even partially hidden objects can be identified and certain waste streams sorted more accurately. The Innosort Flake system allows you to sort plastic fractions from 2 to 12 mm at the same time by color and by polymer type and provides a complete system solution for sorting PET flakes (Fig. 1). A new option for separating black-colored plastics according to type is offered by Unisensor Sensorsysteme GmbH, Karlsruhe, Germany. Their systems Powersort 200 and 360 (Fig. 2) sort up to 10 t/h of plastics. The company relies on high-speed laser spectroscopy. Each individual plastic particle is excited to fluoresce with strong laser light and the emitted light is subsequently analyzed. Since different materials also have different light spectra, the system can sort out parts that have a different light spectrum than the good material. With this positive detection, it is possible to identify a large range of contaminants and separate them from the good stream.

A functioning recycling economy can only be realized with high-quality recyclates, which means that the material flows can be cleaned and selectively filtered. For this purpose, the mechanical engineers offer complete system solutions for post-industrial or post-consumer plastic waste, as well as customized shredders or dryers for use in such production lines. At the beginning of the treatment of plastic waste, however, is always the comminution.

Hosokawa Alpine AG, Augsburg, Germany, has introduced the compact granulator Polymer-Line PL-XS 45/100 (Fig. 3) for the economic comminution of large volume and bulky plastic regrinds. The tangential material feed is intended to ensure safe product feed and low-spray grinding operation. Due to the special geometry of the grinding chamber, according to the company, the regrind is prevented from being thrown out and a smooth machine run is guaranteed. Hosokawa Alpine developed a cross-cutting shear rotor that achieves energy-saving and low-dust comminution. Like the granulator, the system solutions can usually be used as a stand-alone or as a central mill and can be adjusted to the requirements of the recyclate.

Hellweg Maschinenbau GmbH & Co. KG, Roetgen, Germany, offers cutting mills with a digital smart control system. This enables the networked communication of machines with upstream and downstream components as well as with operators in Industry 4.0 environments. The new controller captures and stores the current consumption of the respective granulator as well as, for example, the engine speed and bearing temperatures. It also allows the detection of the condition of blades, screens and V-belts. This allows maintenance to be planned early. The monitoring of the engine speed and the bearing temperature can automatically switch off the cutting mill in the event of a deviation from the nominal value in order to avoid damage to the system. In addition, production-related fluctuations can be compensated in the short term by increasing the grinding performance. The new controller is available for all granulators from the 150 Series upwards.

The Getecha GmbH, Aschaffenburg, Germany, offers with its central mill RS 45090 a comminution solution with a throughput of 900 kg/h with effective sound insulation. By using several different bypass hoppers with special feed rollers, it is possible for full foils, stamped grid, edge strips or profiles, tubes and plate material to be fed into the mill at the same time. According to the manufacturer, the 5-knife rotor with two additional stator blades in the grinding chamber achieves a high performance of the granulator. The hydraulic opening mechanism realizes easy access to the hopper and screen swing for maintenance.

Vecoplan AG from Bad Marienberg, Germany, adapts its shredders of the VIZ series individually to the input and output requirements of the material. The cutting geometry is flexibly adjusted via the rotor and knife assembly as well as the screen selection. The company uses a bolted tool holder plate on the rotor, which is set exactly to the cutting crown size. The user merely exchanges the holder plate and adjusts the cutting geometry to a modified output grain size; the rotor remains in the machine. As a result, time and costs can be saved during maintenance since only the damaged tool holder needs to be replaced. Maintenance is also easier to plan thanks to software that can make predictions based on recorded machine data and can also be operated via the new interface.

One focus of Starlinger & Co. Ges.m.b.H, Vienna, Austria, is the recycling of PET bottles: the recoStar PET iV+ technology converts the input material into recycled PET (rPET). According to the manufacturer, the system meets the strict criteria for food contact and the quality requirements of the further processors. For bottle-to-fiber recycling, the company offers solid-phase polycondensation systems that increase intrinsic viscosity when blending flakes with fibers, to a continuous polymer filter for filtration down to 15 µm.

By expanding the Micromat model line with the Micromat 1500 universal cutting system, Lindner Recyclingtech GmbH, located in Spittal an der Drau, Austria, offers a new entry-level model for stationary universal comminution (Fig. 4). The rotor has a length of 1500 mm and features the new multiplex cutting system. The rotor blades are arranged in three dimensions and are suitable for the comminution of most plastic waste. Due to the particularly aggressive material intervention, an increase in throughput of about 40 % compared to previous technologies is possible. With the aid of the control software, the shredders from Lindner can communicate with the downstream aggregates of the process chain and pass data on the material quality to the extruder. In addition to individual solutions, the company also offers system solutions for post-consumer or post-industrial plastics recycling. With the products of the subsidiary Lindner Washtech GmbH, Grossbottwar, Germany, system solutions are developed that cover the entire process chain of comminution, pre-washing, friction washing, separation and drying.

The MetaPure technology of Krones AG, Neutraubling, Germany, is specially designed for the washing and decontamination of PET flakes. The flakes go through the process steps of pretreatment, caustic washing and final hot rinse (Fig. 5). To close the material cycle in the food industry, the flakes are processed in the final step in the MetaPure S decontamination module. By means of solid phase post-condensation, the intrinsic viscosity can be increased and matched to the desired end product. The recycling of polyolefins faces further challenges. On the one hand, organic residues must be removed and the resulting odor pollution reduced. In the combined preparation of polyolefins and PET, the material can be separated in the floating test because of the low density of the polyolefins. Also in polyolefin recycling, high-quality reuse is expected to be developed. This is why Krones has modified the MetaPure W-PO washing module and adapted it exactly to polyolefins.

With the IR-Clean infrared rotary drum, Kreyenborg GmbH & Co. KG, Senden, Germany, offers a solution tailored precisely to the requirements for PET decontamination (Fig. 6). The material to be treated passes through a metering unit into the rotary drum, in which the welded-in screw flight and the continuous rotation ensures a homogeneous material flow with a defined residence time (first-in/first-out principle). In the process, the material is mixed and the surface is permanently replaced, so that the infrared elements produce a homogeneous heating. Infrared rotary drums work without vacuum technology and can be individually designed in size and length. They can either be integrated into an existing extrusion line or used as a stand-alone solution.

The processing of recycled material poses a great challenge to the processing process. On the one hand, material handling is influenced by low bulk densities, on the other hand recyclates are processed which have a high contamination by organic and inorganic foreign substances and different colors. In the processing plant therefore, different material streams with different melt viscosities must be processed separately. Main tasks for the treatment plants are the degassing of moisture and low molecular weight components, the melt filtration to reduce the impurity level, and the incorporation of additives and fillers to adjust the properties so that the highest possible use is possible. Numerous machine and plant engineers offer solutions for inline control and regulation of material properties.

Already with metering, a significant difference between secondary and primary material comes into play: like virtually every recycled material, waste plastics are heterogeneous in size, shape and bulk density. The right choice of metering technology is very important in order to ensure an optimal flow of bulk material. For example, the Smart weigh belt feeder Coperion K-Tron Germany GmbH, Offenbach, Germany, is suitable for processing recyclates in which the bulk density often fluctuates. If smaller recyclates or flakes are metered or if it is necessary to introduce glass fibers into compounding processes, vibratory feeders are suitable. If the material has very irregular sizes or shapes, screw feeders should be used whose rotating screws feed and dispense the material from a container. The screws and the horizontal agitator ensure a uniform mass flow. A distinction is made between single and twin screw feeders (Fig. 7). Both types are available in gravimetric and volumetric versions.

To remove contamination in the form of organic and inorganic contaminants, melt filtration systems are used. These filter systems are designed either for continuous operation, with the possibility of replacing filters during the process, or for discontinuous operation, in which a filter replacement requires an interruption of production. Nordson Corporation, Ohio, USA, uses its BKG screen changers with four screen cavities for melt filtration. Each pair of screen cavities is positioned so that it can filter the respective melt streams until the displacer removes one of the cavities from the process to remove contaminants by backwashing. The backwash sequence starts automatically when the pressure difference due to an accumulation of impurities increases to a predetermined level. A completely different approach to the automatic removal of contaminants is the Nordson R-Type filtration system for recycling highly contaminated plastics (Fig. 8). It has a cylindrical head with knives arranged in the form of a spiral on its surface and conveying impurities forward with the rotary motion of the separating head. The separating head is enclosed by a stationary filter element. As contaminated melt flows from the inlet into the cylindrical space between the rotating separation head and the filter basket, the blades detect the debris while the cleaned melt flows through the filter basket into flow channels that open into an outlet. At the same time, the separating head, together with a discharge screw connected to the separating head, carries out a rotary movement which transports the highly concentrated, contaminated material through cooling zones, where it is finally collected in collecting containers. The design allows even loading of the filter basket.

In the final step, the recycled plastic waste must go through a compounding process to meet the quality requirements of the customer. When compounding, the screw melts the starting materials and mixes them. The melt is degassed and conveyed in the direction of the shaping outlet opening. When processing recyclates, a standard single-screw extruder that is charged volumetrically is not always sufficient. Its dispersing and degassing performance is often too low for the processing of large quantities of recyclates and leads to a low quality in the final product. One possibility for processing large quantities of recyclates is provided by the twin-screw extruder.

Coperion GmbH, Stuttgart, Germany, offers two series of twin-screw extruders for the processing of recyclates: the high-end ZSK and the STS series (Fig. 9). In both model series, additives, fillers and reinforcing materials are added to the process section via metering units. Thanks to their high torque and the coordinated process parameters, the extruders are able to absorb and process high proportions of calcium carbonate, talc, glass or natural fibers. The better degassing over a larger surface additionally causes a reduction of the odor load in the regranulate. The technology can be used for a variety of applications in the production of recycled plastics: for regranulation of plastics such as HDPE, PP, ABS, PS and PVC, for the production of films, for PET recycling and also for the upcycling of various materials. ICMA San Giorgio S.p.A, San Giorgio, Italy, is taking it one step further by aligning its compounding and extrusion lines directly with plastics recycling and the processing of biodegradable plastic compounds. At the heart of the processing line is a co-rotating twin-screw extruder.

At the Erema Group, Ansfelden, Austria, complete system solutions are tailored precisely to the requirements of the material to be recycled. The company covers every step of the process, from comminution to granulation. At the heart of the new Intarema ZeroWastePro (Fig. 10) is the cutter compactor. It adjusts itself permanently to the input material and can process it constantly even with fluctuating properties, such as humidity and density. In just one step, the material is cut, homogenized, heated, dried, compressed, buffered and metered into the following single-screw extruder. The opposite processing of the materials in the cutter compactor relative to the single screw extruder can increase the feeding of the extruder and the throughput.

Erema was also able to present new developments in terms of melt filters, odor neutralization, Industry 4.0 and in-line measurement technology. It now achieves, for example, food grade HDPE from post-consumer material with the Intarema TVEplus RegrindPro extrusion system in combination with the ReFresher module. The QualityOn package, which measures MVR, IV, color, and polymer composition using Raman spectroscopy during the process on the machine, provides early detection of faulty material.

A co-operation between the Next Generation Recycling Machines GmbH (NRG) from Feldkirchen in Austria and the Kuhne GmbH, Sankt Augustin, Germany, serves for the direct production of rPET foils. After melt production in the extruder and appropriate filtration, the PET melt enters the LSP reactor (polycondensation reactor). Here, harmful chemicals are removed while adjusting the intrinsic viscosity. The PET melt coming from the recycling extruder is transferred to the foil plant. The T-channel nozzle with internal cover, specially developed for the production of PET foils, distributes the melt into the calender. According to NGR, the rPET foils produced in this way are characterized by low dimensional tolerances and uniform strength with very good optical properties.

A good example for the careful use of resources is the “Blue” initiative of Pöppelmann GmbH & Co. KG, Lohne, Germany. It strives for a closed material cycle and tries to make its products and processes resource-saving (Design for recycling). The company’s product development begins with a feasibility study that focuses on eco-design. This involves integrating environmental aspects into the design of an article, taking into account the entire life cycle of the product. In addition, products are designed that are suitable for multiple use.

The recycling economy for plastics works well wherever there are enough recyclates. Overall, the amount of available recyclates is still relatively low. In order to increase availability, the KraussMaffei Group from Munich, Germany, has developed a digital marketplace where suppliers and customers can meet. If you need recyclate in the future, you can send your demand request to Polymore. The platform then forwards them to the relevant providers.

The multi-faceted demands that arise in the preparation and processing of recyclates can already be addressed by industry in different ways. At least on the technological level, there is nothing to prevent the recycling of plastic waste. Achieving a functioning recycling economy is thus an active decision of manufacturers and consumers. This decision can and must be supported by political regulations and subsidies.

Starlinger & Co.GmbH Maschinenfabrik 

https://www.starlinger.com

EREMA Engineering Recycling Maschinen und Anlagen GmbH 

https://www.erema.com/

Hosokawa Alpine AG  

https://www.hosokawa-alpine.de/

Vecoplan AG  

https://www.vecoplan.de

Hellweg Maschinenbau GmbH & Co. KG 

https://www.hellweg-maschinenbau.de

NGR Next Generation Recyclingmaschinen GmbH 

https://www.ngr-world.com/

Kreyenborg GmbH & Co. KG  

https://www.kreyenborg.com

Coperion K-Tron (Schweiz) GmbH  

http://www.coperionktron.com/

Lindner-Recyclingtech GmbH  

https://www.lindner.com

TOMRA Sorting GmbH  

https://www.tomra.com

Ausgabenartikel

Complex chain: recycling materials (such as these shredded and washed fishing nets) have to pass through several stations, beginning with collecting and sorting, before they can be mechanically recycled

Fig. 8. Melt filtration: the cylindrical head of the HiCon R-Type with knives ensures a uniform load when recycling heavily contaminated plastics

Fig. 1. Innosort Flake allows simultaneous sorting by color and polymer type

Fig. 10. The ZeroWastePro is specially designed for the in-house recycling of PE and PP foils

Fig. 2. Also black colored plastics can be sorted with the Powersort 360 with a throughput of 10  t/h

Fig. 3. Polymer-Line: a compact granulator for the economic comminution of large volume and bulky plastics

Fig. 4. Micromat 1500: a new model in the field of stationary universal shredders

Fig. 5. MetaPure: a washing module for PET flakes

Fig. 6. IR-Clean: individually adjustable length of infrared rotary drum for processing PET flakes

Fig. 7. Single and twin screw metering units (right) are available in gravimetric and volumetric versions

Fig. 9. Twin screw extruder ZSK Mc18 for high throughputs in the treatment of recycled materials

kk_SPEC_TB_Recycling - Hauptartikel

<b>Philipp Schäfer, M.Sc.,</b> does research in the fields of compounding and reactive extrusion.