Cabopol: biodegradable compounds with Coperion technology

image_thumb[1]Cabopol (Porto de Mós, Portugal) started the production of BIOMIND, a new biodegradable poliester/starch based compound to be used for the production of disposable nappies and cutlery, rubbish bags, food packaging, shopping bags, agricultural films and many other household, industrial and agricultural applications.The BIOMIND compound will be presented at K 2010.

Cabopol is one of the ten largest compounders in Europe, with a capacity of 75 000 tons per year wich includes unplasticised and plasticised PVC, various thermoplastic elastomers, halogen free flame retardant compounds and polypropylene compounds for the automotive industry.  With the new BIOMIND plant – a turn key project supplied by Coperion (Stuttgart, Germany) -, Cabopol is now the first manufacturer of biodegradable polymers on the Iberian Peninsula. The plant started its trial phase in January 2010, and the industrial phase in early spring.

The processing system includes materials handling for all raw materials – storage, conveying, weighing and dosing – as well as compounding with downstream pelletizing and drying. Biodegradable compounds based on compostable polyesters with and without starch are being manufactured. The materials supply system stands out for a high flexibility, allowing the addition of several different components. The processing extruder, a ZSK MEGAcompounder PLUS, has a ZS-B twin screw side feeder and a venting unit. The die discharges into a water bath for strand cooling followed by suction drying of the strand surface prior to strand pelletizing. All the peripherals are integrated into the EpcNT plant control system. A modem allows remote software updates and monitoring of the compounding plant.

Cabopol procured a ZSK 26 MEGAcompounder laboratory extruder especially for this project and during the optimisation of the screw geometry and process technology was able to make use of know-how from Coperion. It is the formulations including starch that represent a particular challenge: The melting zone in the compounding extruder has to not only melt the polymer, but also plastify the non-melting starch by adding liquid.

The plant was installed in a three storey steel framework. The upper level is used for the management of pellets and powders. It houses the intermediate materials storage system with day bins, four big bag emptying stations (one of which is ATEX rated for the starch), a sack station as well as the central aspiration system. On the mezzanine level there are gravimetric dosing stations for solid material, and pumping stations for liquids are located on the ground level along with the ZSK MEGAcompounder PLUS compounding extruder.