markets feature | Polyolefin additives
Controlled migration Norner is one of 11 partners involved in a Norwegian project to investigate the migration of chemicals into food from packaging materials. “It’s very important that food is not polluted by
potentially hazardous substances migrating from the food contact material (FCM) into the food,” Svein Jamtvedt, principal researcher at Norner, told del- egates at the Polyolefin Additives conference. The Chemical in Food Packaging project is a three-
The bag on the left uses DuPont’s Entira anti-static additive
15%, surface resistivity dropped by a factor of 10,000. At 20% loading, it fell by a further 10 times. At the same time, Palsgaard of Denmark has
developed a plant-based anti-static additive with long-lasting performance. The product, called 8111, is a long-chain glyceride that has good optical properties – such as gloss. The longer chain length means that migration is slow – and the effect lasts for longer. It is one of a number of anti-static agents – based on
lipid sources such as palm and rapeseed oil, offered by the company. By blending different glycerides, the company can tune the performance – balancing quick migration (which benefits the production process) with slower migration (which is good for printing and sealing operations).
Permanent effect Karlheinz Hausmann, an R&D fellow at DuPont in Switzerland, said that the company’s Entira permanent anti-static agents are ionomers of ethylene methacrylic acid copolymer. Benefits include instant action – and permanent effect – as well as high clarity and smooth surface with no yellowing. They can be applied to a range of polyolefins, including all types of PE, PP (including BOPP), and other polymers such as EVA and HIPS. The company offers two commercial grades: AS MK400; and SD100. In LLDPE blown film (50 microns thick), addition of AS MK400 at a 20% loading reduced surface resistivity by four orders of magnitude. For LDPE and mPE, raising the processing temperature from 190 to 220°C also helped to reduce surface resistivity – by as much as an order of magnitude – for the same loading and film thickness. Performance was also improved by conditioning in a
moisture chamber for 48 hours, showing that a higher moisture content was a benefit to anti-static perfor- mance. DuPont also tested the effect of ageing – and found that it did not affect performance.
20 FILM & SHEET EXTRUSION | October 2016
year project that began in 2014. Other partners include packaging producer Elopak, food producers including Bama, and two grocery chains – Rema 1000 and Unil. Food contact materials are governed by a number of EU and other regulations, and must be tested for overall and specific migration. Of the 27 materials tested in the project, 16 had a polyethylene layer in contact with the food. All the materials were multi-layers or laminates, and most had a barrier layer such as aluminium, nylon or EVOH. Many also had tie-layers or adhesive layers. Some overall migration was carried out, but the
project focused on specific migration. Testing methods included: FTIR, to give information on composition and chemical structure; Soxhlet extraction, after which the extract was analysed by methods such as HPLC or GC-MS; and microscopy, which was used to analyse the film structures. The researchers were concerned that several
‘non-listed’ substances were present at levels above the accepted 10 parts per billion (ppb) level. For example, polyolefin oligomers were commonly
found to have migrated and were found at levels of around 0.6 parts per million (ppm). “Polyolefin will always contain oligomers – but should each oligomer also be lower than 10ppb?” he said. Similarly, an anti-oxidant such as P168 will be
oxidised to P168-phosphate when doing its job correctly – but should levels of P168-phosphate be restricted to 10ppb, he asked. P168 is currently approved for a level of 60ppm. The project team is now looking for further funding to look into these areas of concern, he said.
Click on the links for more information: ❙
www.sunshows.com.cn ❙
www.dowcorning.com ❙
www.teknorapex.com ❙
www.tosaf.com ❙
www.amiplastics.com ❙
www.adk.co.jp ❙
www.palsgaard.com ❙
www.dupont.com ❙
www.norner.no
www.filmandsheet.com
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