MATERIALS | BIOPLASTICS
(formerly Total Corbion PLA) is a specialist in lactide monomers and a leading producer of polylactic acid (PLA), a bio-based and biodegradable polymer made from renewable resources. Its Luminy PLA portfolio includes both high heat and standard PLA grades. Currently all Luminy production is focused on its 75,000 tonnes/yr plant at Rayong in Thailand (plans to build a second production plant with a capacity of 100,000 tonnes/yr at Grandpuits in France were halted last summer). Luminy PLA is already used in a wide range of
Below: Boplat’s durable and colourful lunchboxes are injection moulded in Luminy PLA from TotalEnergies Corbion
applications but could be set for more diverse uses in future, according to Vladislav Jaso, application specialist at the company. “PLA is well known for its use in packaging and especially food packaging. However, as a versatile polymer it can also be used in durable applica- tions,” he said. “PLA compounding is not much different to making compounds of traditional plastics, though attention needs to be paid to proper purging of the machine before compounding and pre-drying of the PLA material. Screw configuration will depend on the additives used but Luminy PLA can be processed on conventional compounding equipment where a co-rotating intermeshing twin screw extruder with a L/D ratio of at least 28:1 is preferred.” Control of crystallisation is a key consideration in development of PLA compounds, especially for injection moulded applications. “PLA and [the isomer] PDLA, often used as nucleating agent, can be added with two separate feeders or as a dry-blend mixture through a side feeder, after which there should be enough time and mixing capacity to ensure homogeneous mixing. A liquid feeder can be added if required, and it is recom- mended to have atmospheric and/or vacuum degassing sections along the barrel to remove volatiles,” he advised. Jaso says notable applications for its Luminy
products include cosmetic containers made from L105 injection moulding grade filled with wood chips and natural biodegrad- able binders. This is said to offer a stone/wood look and feel, good processing econom- ics, and combines luxury and almost
unlimited design possibilities
with reduced weight. PLA compounds are also used for caps and
IMAGE: BOPLAT/ TOTALENERGIES CORBION
16
closures on glass containers where the PLA resin is combined with by-products of industrial side- streams and camellia seed shells. The compounds
INJECTION WORLD | July/August 2024
have been used to replace thermoset polymers where they are said to reduce environmental impact while providing a luxurious feel. Colour masterbatches are used to replace the coating process used in the incumbent product. PLA compounds are also being used for
children’s toys because they are considered durable with good impact and heat resistance and excellent surface finish and colourability. In August last year, TotalEnergies Corbion introduced a 30% recycled content PLA grade to the UK market to coincide with the implementation of the plastics packaging tax (PPT).
Growing in PLA US headquartered Natureworks operates a 150,000 tonnes/yr PLA production facility at Blair in Nebraska. The plant started up in 2002 and produces PLA polymer under the Ingeo name using corn as a feedstock. The company, now a JV between US agriproducts group Cargill and Thai petrochemicals group PTT Global Chemical, has started construction of a second production plant in Nakhon Sawan Province in Thailand. NatureWorks recently secured funding of US$350 million from Krungthai Bank in Thailand, for a PLA manufacturing plant that it plans to build in the country. “The funding will enable us to expand our
international customer access to fully biobased, low-carbon biomaterials,” said Erik Ripple, presi- dent and CEO of NatureWorks. The new facility is designed to be a fully integrat-
ed PLA complex, including production sites for lactic acid, lactide and polymer. It will produce the company’s full portfolio of Ingeo PLA grades, with an annual capacity of 75,000 tonnes. Biopolymers made at this site will be made from sugarcane from farms within a 50km radius of the Nakhon Sawan Biocom- plex. It is scheduled to reach full production in 2025. Natureworks offers a range of Ingeo grades, covering applications as diverse as food and cosmetics packaging — it has developed a coffee capsule system with Italy’s IMA Coffee — through to non-wovens and medical products. The material is also well suited to filament-based 3D printing projects.
Degradable additives Biodegradable polyesters such as PLA can be difficult to process and final products can suffer from brittleness. German chemicals group Wacker has used two of its additive products — Vinnex or Vinnex Eco and the Genioplast Pellet — in conjunction to improve both characteristics. The Vinnex range of
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