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FAIR-CT96-3070
Production of biodegradable films and bottles made of polylactic acid polymers (PLA) |
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Proposal No: | FAIR-CT96-3070 |
| Date Prepared: | July 2001, November 1999, May 1999 | |
| Source: | Progress Report September 2000
Publication Progress Report September 1999 First Annual Progress Report |
Summary
This summary describes the activities carried out during the period from 01/09/98 to 31/08/99, presented under the task headings.
Task 1. The main objective of task 1 consists of converting crude lactic acid into lactic ester and to purify the latter by continuous distillation in order to reach the purity required by task 2 for the synthesis of lactide. Particular attention has to be given to the economy of the process by improving mass balances, yields, energy consumption and kinetics. As the main technical problems have been resolved during this second year, the third year of the project will be devoted to the pilot scale production of ethyl lactate to be able to supply task 2 with the product. Particular emphasis will paid to the shift from batch mode to continuous mode with control of residence time, side reactions and racemization during the process.
Task 2. This second year was mainly devoted to the start up of various process steps (oligomerization, cyclisation, distillation and melt-crystallisation). The pilot plant was finalising and constructed. Some problems were encountered, requiring further action in order to make the unit operational. The next step involved programming/regulation work in order to be able to control and thus optimise each parameter involved in the overall process. Very good results have been obtained within the oligomerization and cyclisation process which allowed the crude product to be purified directly by melt crystallisation. Because of time delays in supply of lactide, it was decided for the moment to bypass the distillation step and to delay it optimisation. Hence, the following months will be used to optimise the main processes (oligomerization, cyclisation and melt crystallisation) in order to supply other participants with substantial quantities of lactide. Once, this has been done, then yield problem will be resolved with optimisation of the distillation step.
Task 3. During the second 12 months of the project, the main objective proposed within this section was to develop the production of polylactide polymer using production machinery in the form of a closely intermeshing twin screw extruder of 40 mm screw diameter. Due to the fact that no lactide was supplied from task 2, it was decided to postpone this polymerisation development into the final year and continue to develop materials suitable for the final processing tasks.
For the basic studies of polymer application/film extrusion, a laboratory extruder with 25 mm screw diameter was used to develop block-copolymers based on lactide and ethyleneglycol, that exhibit different thermal properties, especially glass transition temperatures below room temperature, and have a tough flexible mechanical behaviour. For the polymer application already existing polylactide polymer has been modified chemically by means of reactive extrusion and used in injection moulding and blow moulding processes to determine the feasibility of using PLA as a blow moulding material.
The polymerisation equipment is completed. An additional single screw extruder to feed lactide into the reactive system will be added within the next months.
Task 4. The evaluation of the PLA bottles was completed during this year. Several meetings were held between participants in order to discuss how the PLA material could be improved, and to produce the technical specifications. As the major task assigned to ACE Veka Film Division has not started yet, their activities have been limited to the participation at various meetings and contributing to the collection of information that is a continuing activity for all participants (meetings, conferences, test of materials, etc...). ACE also played an active part in the SPE Conference (that incorporated a biodegradable theme) in October 1998 in Dusseldorf and in the Index Fair in April 1999 in Geneva.
Task 5. This was initiated in March 1999, with identification of the individual steps to be performed in order to reach the objectives of this task. The following steps were identified and started:
The following months will be devoted to preparation of the final report as well as a summary for distribution, together with creation of an efficient data base that requires collection of missing information and encoding of all data. Plans for attending the Wolfsburg 2000 Symposium, that includes an exhibition with 300 square meters devoted to biologically degradable material, have been initiated.
Summary
Introduction Activities over the first year were exclusively dedicated to building the demonstration unit which will be used to synthesise 30 tons of L-lactide par year. Based on experience accumulated during research project AIR3-CT94-2285, the first phase consisted of:
Activities These activities relate to the Escanaffles site where GALACTIC runs its production. The technical specification for all the equipment have been written to enable tenders and quotations to be made, followed by selection of partners to build the plant. The main elements have been supplied (some ancillary elements still need to be supplied) the assembling and the piping work started. Currently, these tasks are nearing completion. The next step will be to start the unit using water and latter on with reagents to obtain the first lactide. The following months will then be used to improve quality and optimise the process in terms of yield and energy use.
Progress As indicated, the first year of the project has been focused on the engineering work in order to ensure a correct sizing of the pilot unit allowing the manufacture of about 80 tons ethyl lactate. Once delivered, the equipment has been erected at the Escanaffles production site in Belgium. Piping and connection work has been completed in order to allow the unit to start up as planned. As the time this report was written the first results were in hand and analysis performed on first samples are encouraging. First batches were expected at the beginning of 1999.
During the first 12 month of the project, the requirements for the materials needed for the final production applications had also to be collected and pathways to produce PLA-based polymeric materials which fulfil the requirements had to be developed. In addition the polymerisation experimental setup had to be completed and additional polymerisation tests on the laboratory extrusion machinery had to be conducted to achieve final information relating to the scale-up of the polymerisation process.
For the various polymer applications both film extrusion and stretch blow moulding tests were carried out, as well as basic studies including crystallisation kinetics of PLA-polymers, plasticiser studies for PLA modification and studies of the uniaxial orientation of PLA- polymers have been conducted. This has enabled a basic knowledge database to be constructed on which further developments can be based. From these studies the first material combinations will be selected for each of the processing tasks to determine the basic need and to confirm the information.
The polymerisation equipment has been completed. Several additional pieces of equipment have been either bought or built and added to the existing twin screw extruder system. The added equipment includes a Sulzer static mixer for dispersion of the stabiliser within the polymerised material, a requirement shown in the AIR project. In addition a Buss co-kneader has been connected to the twin screw extruder. The co-kneader can be used to melt the lactide if necessary and introduce the molten and heated monomer into the twin screw extruder to reduce the screw length required for preparation. This raises the possibility of enhancing the throughput rate of the machine, thus improving the economics.
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