Automakers are using more plastic parts

Plastic recycling in the automotive industry

The use of plastics in automobile construction has been increasing continuously for 20 years. The main reason for this is the reduction in vehicle weight: a lighter car uses less fuel; this in turn means fewer exhaust gases and lower oil consumption. Plastics are also corrosion-resistant, offer additional security thanks to their elasticity and flexibility, have very good thermal insulation properties, reduce the noise level and enable optimal use of space. The article presents four case studies.

recoSTAR universal with CaCO3 dosing unit. Image: Starlinger & Co. GmbH

Today vehicles usually have a plastic content of 12 to 15 percent. With an average dead weight of 1,300 kg, this would be 150 to 200 kg of plastic per car.

Recycling of plastics from end-of-life vehicles

These figures clearly show the great recycling potential for plastics from the automotive sector. The EU Directive 2000/53 / EC on end-of-life vehicles became the driving motor for recycling in the automotive industry through the implementation of suitable collection systems for end-of-life vehicles and stricter environmental requirements. It sets targets for the recovery and recycling of vehicle components and offers manufacturers an incentive to consider the reuse and recycling of components as early as the design of their vehicles. The guideline currently provides for the reuse and recycling of at least 85 percent of the average vehicle weight per year for all end-of-life vehicles, including 5 percent energy recovery. Since January 2015, the reuse or recycling rate should be at least 95 percent of the average vehicle weight per year.

Starlinger recoSTAR direct 85. Image: Starlinger & Co. GmbH

The plastic components in automotive engineering are mostly injection molded parts, for example dashboards, bumpers, tanks for various liquids, handles, buttons, housings, containers, clamps, sockets and others. The challenge in recycling is that reinforced plastics (e.g. with glass bead or glass or carbon fiber content) or plastic mixtures (e.g. PP with EPDM or TPE) are used or two- or multi-component injection molding is used.

Removal of odors and foreign matter, upcycling, flexibility

Plastic parts from the automotive industry place special demands on the recycling process so that the recycled product is suitable for further use. The elimination of odors and foreign substances through high vacuum extraction and melt filtration as well as the use of additives for upcycling are key factors that must be taken into account. A flexible process that enables quick and efficient material changes and a wear-resistant system - for processing reinforced plastics with, for example, glass fiber - enable recyclers to process a number of different input materials.

Polypropylene regrind from car batteries. Image: Starlinger & Co. GmbH

In order to produce high-quality regranulate that can be easily reused, volatile and solid foreign matter must be removed thoroughly. Special vacuum degassing extruder modules enable colored and contaminated parts to be reprocessed. Depending on the type of contamination, different filter systems and formats are used to keep the melt loss as low as possible.

Recycling of old plastics from the automotive industry

Starlinger recycling technology, a division of the Austrian mechanical engineering company Starlinger & Co. GmbH, supplies systems for recycling plastics from end-of-life vehicles. The company has already installed several systems for this special area.

The machine types recoSTAR direct, recoSTAR basic and recoSTAR universal basically use the same process sequence and differ, depending on the input material to be processed, mainly in the design of the pretreatment area. Each machine can be equipped with a degassing and high vacuum unit, melt filtration and one of the four available granulation systems.

Case study 1: heavy grist

Heavy regrind (> 300 g / l), for example from injection molded parts such as car bumpers, can be processed in the recoSTAR direct recycling system without additional pre-shredding or compression. The ground material is fed directly into the extruder from a material hopper via a screw conveyor. The particular advantage of the recoSTAR direct is that no heating or other material pretreatment is required before extrusion.

> Input material: regrind mixture of PP, POM and ABS; Production waste: PP (sometimes with up to 20 percent CaCO3), POM, ABS; Previous solution: contract recycling

> Objective: Compounding additives: Upcycling by adding calcium carbonate and talc (both in powder form) up to a proportion of 20 percent

> System: recoSTAR direct 85 with water ring granulation

> Special technical features: automatic loading from the mixing silo controlled by the extruder load; including big bag unloading station for powder and dosing unit for additives; wear-resistant cylinder and screw construction

> Use of the regranulate: For the production of invisible interior panels for cars. 100 percent of the regranulate is used in-house, up to 40 percent is added in the production process.

Granules from car batteries. Image: Starlinger & Co. GmbH

Case studies 2 and 3: Wet and pre-shredded waste

Pre-shredded, light, dirty, moist or hygroscopic waste material, for example from old car batteries, is pre-treated in the agglomerator of the recoSTAR basic recycling system, which is equipped with a rotating disc with knives on the bottom. The friction process heats and dries the mixture, compressing it and bringing it close to the melting point. The material is continuously fed into the extruder by means of centrifugal force, with the loading being automatically controlled by the utilization of the agglomerator motor. The optional air purging function on the agglomerator removes moisture and any intense odors during the pretreatment.

Case study 2:

> Input material: HDPE regrind from fuel tanks; washed old plastic. Contaminated by: metals, wood, rubber, other substances

> Objective: to eliminate odors for later reuse

> System: recoSTAR basic 85 D-VAC (double vacuum)

> Special technical features: agglomerator air flushing (due to high humidity, odor elimination); double extruder degassing with high vacuum; the continuous rotary filter filters the melt with minimal loss

> Use of regranulate: reused in the manufacture of new fuel tanks

Case Study 3:

> Input material: regrind from old car batteries (polypropylene); Contamination: sulfuric acid (if the pre-wash is insufficient)

> Objective: Thoroughly remove all impurities

> System: 2 x recoSTAR basic 165 VAC

> Special technical features: delivered as a turnkey system; Dosing unit for adding masterbatch (upcycling by adding two components); Parts in contact with material, gas or water made of stainless steel; no wearing parts in the agglomerator

> Use of the regranulate: for the production of new car batteries

Old car batteries before recycling. Image: Starlinger & Co. GmbH

Case Study 4: Difficult-to-Grind Materials and Mixtures

Equipped with a high-performance single-shaft shredder arranged parallel to the extruder, the recoSTAR universal can also process materials that are difficult to shred, such as injection-molded parts that have not been pre-shredded, as well as material mixtures with different bulk densities. The single-shaft shredder shreds the material, which is then fed cold into the extruder. The speed-controlled dosing screw ensures uniform and continuous feeding, while the construction with triple drive enables precise material dosing and output control. If required, an optional rotor temperature control can be used for processing moist and / or hygroscopic materials.

> Input material: mixed injection molded parts; PA 6.6 + up to 30 percent glass fiber, mixtures of PC & ABS, POM, PP; Injection molded parts, clean production waste

> Objective: processing of polyoxymethylene (POM): special treatment, efficient material change; improved wear resistance for fiberglass processing; Addition of CaCO3-Powder (upcycling)

> System: recoSTAR universal 65 H-VAC

> Special technical features: high vacuum for better degassing; hydraulic backwash for a filter unit <200 ┬Ám, less backwash loss and longer service life of the filter sieves; automatic strand pelletizing

> Use of regranulate: Part of it is reused in production, a small part is resold.

About Starlinger

Starlinger recycling technology is a division of the Austrian Starlinger & Co Ges.m.b.H., the world market leader in machines and complete systems for the production of woven plastic packaging. For more than 25 years, Starlinger recycling technology has been supplying machine solutions for recycling and refining a variety of plastics such as PE, PP, PA, PS, BOPP and PET. Starlinger's PET recycling systems produce food-safe rPET in a process that numerous brand owners and national and international authorities have already certified for food applications. A worldwide sales and service network and comprehensive technical advice support customers in achieving optimal production results.

Sigrid Eder, Starlinger & Co. Gesellschaft m.b.H., Vienna / Austria, [email protected]