Special extrusion lines for bioplastic compounds

The biodegradable and compostable plastics sector is growing steadily, and this is partly due to the fact that several measures have been taken, especially in the EU, to cut down on single-use plastics. For instance, it is estimated that the market for polyvinyl alcohol (PVA), a water-soluble thermoplastic polymer predominantly used in food packaging, will record a compound annual growth rate (CAGR) of more than 6% over the 2021-2026 period. To meet market requirements, Bausano introduced its special extrusion lines, of the MD Nextmover product family, for the production of water-soluble bioplastic granules, which are ideal for subsequent blown film extrusion.

What is PVA?

Polyvinyl alcohol (PvOH), also known as PVA, is a material that has a low environmental impact as it is fully biocompatible and non-toxic. It also has low oxygen permeability in the absence of moisture, according to Alessandro Ruotolo, Bausano’s Materials Engineer, who adds:  “As a result, PVA films are increasingly used for the packaging of food, pharmaceuticals and personal care products, as well as in disposable packaging, such as detergent tablets. In addition, water-soluble bioplastics made from plant-based raw materials are available as an alternative to polyvinyl alcohol. In both cases, given the complexity of the material, the granulation process requires a different approach to traditional plastics, which is why all of Bausano’s special lines are a powerhouse of technology that can be fully tailored to the customer’s specific requirements.”

Extruder configuration

In particular, in order to determine how to correctly configure counter-rotating twin-screw extruders, which perform better than co-rotating extruders in the case of water-soluble bioplastics, the Bausano team of experts takes several aspects into consideration. The first aspect is the length of the barrel, which must allow the material to pass through for the time strictly necessary for the screws to process it. In fact, if it remains there for too long, it will be subject to excessive stress. The second aspect is temperature. In fact, processing takes place at much higher temperatures than with PVC, for example. Moreover, in order to obtain a granule without impurities, the gel point must be determined with absolute accuracy. The final aspect is the type of head and cutting technology used. These help to determine the correct way to cool the extrudate, which is water-soluble and therefore cannot be cooled with water, unlike polymers such as polyolefins. Bausano pays special attention to this step to ensure that the quality of the granules is as high as possible.

Developing new technologies to process eco-friendly plastics

‘Our special lines for bioplastics processing, and particularly water-soluble plastics, are a clear example of the fact that our company is committed to respecting the environment. Biodegradable films are now considered an integral part of sustainable global economic development and, in order to meet the demands of an increasingly discerning and conscious market, we allocate substantial resources in researching and developing new technologies to process eco-friendly plastics. Efforts are therefore being made to support all manufacturers who, in these times of ecological transition, are entering this business,’ concludes Mr Alessandro Ruotolo.

The MD Nextmover Series is a new generation extruder with design concept and implementation of lines based on the integration between mechanical technologies and ICT: smart remote control and intuitive human-machine interface. Bausano offers its  customers the opportunity of transforming their companies into smart factories, where productivity increases and working conditions improve. Each extruder is unique, even different from the others belonging to the same series. What never changes is the ability to optimise production, cutting down costs and passing any tests with exceptional results. The MD Nextmover Series is integrated with smart energy system, digital extruder control, predictive maintenance capability, I.E.4 motors, variable speed screws  with thermostat, stainless steel hopper for easier cleaning, control unit for gear box lubrication, venting exclusive and patented “multidrive” system, thrust bearing with high load capacity, protection for barrel with double cavity, and asynchronous motors connected to an inverter.

Bausano has introduced its MD Nextmover 125/25 twin-screw extrusion line in an online demonstration in April 2021 where two Multidrive-powered MD Plus and MD Nextmover lines were shown, and where its technical team operated the MD Nextmover 125/25 extruder to production levels of 800-1,000kg/h. The technicians also explained the different solutions and configurations for various production ranges and showcased the extruder’s Smart Energy System, an innovative contactless cylinder heating system that delivers energy savings of up to 35%. 

Founded in 1946, Bausano is an international leader in the design and production of customised extrusion lines for the transformation of plastic materials. Quality, flexibility and attentiveness to the individual needs of every customer: these are the company’s distinctive features in developing tailor-made solutions for the extrusion of pipes, granules, profiles and wood plastic composites (WPC) for a wide variety of applications as well as material used in the medical sector. Bausano is a strategic partner to its customers by virtue of its complete control over the value chain, a highly qualified pre-sales consultancy service as well as after-sales support with specialised operators who are able to work on-site within 24 hours from a request. The company’s headquarters are located near Turin, Italy, and it has production units in Brazil and India. Its U.S. offices are based in Oswego, Ill. and Houston.