MATERIALS | FILM ADDITIVES
IMAGE: MILLIKEN
Above: Milliken’s UltraGuard additives can improve moisture barrier and recyclability of polyolefin packaging films
masterbatches to enhance barrier properties in polyethylene. Milliken says the products have the potential to help film producers eliminate the need for metalized layers and to enable recyclable multilayer structures with good barrier to moisture. In polyethylene-based structures, HDPE often is
favoured over LDPE or LLDPE when higher levels of moisture barrier are required. Milliken says UltraGuard can enable HDPE to achieve a WVTR (water vapour transmission rate) below 2g/m2 in a 25-micron film.
products. However, according to Palsgaard, which specialises in a wide range of additives for foods and also plastics, the use of additives in food packaging films has become a target of concern with regard to potential harmful effects on human health. “There is good reason for this, since anti-fogs normally work by migration, and it is important to make sure that no traces of them will compromise the safety of the food,” the company says. “This is why many synthetic fossil-based anti-fogs are subject to strict migration and concentration limits, which can be difficult to meet with innovative film structures for thin-wall packaging.”
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Right: Einar additive pellets from Palsgaard are plant-based and available in an easy-to- handle pellet form
HDPE is not always the best solution in terms of toughness and mechanicals, however, which is why monolayer films may require the use of blends of different types of PE — LDPE may be mixed with HDPE to achieve a more stable bubble or to reduce wrinkling, for example. According to Milliken, the reduction in barrier caused by the use of LDPE can be compensated for using UltraGuard. Another option open to converters is to create a multilayer PE film with a core layer of HDPE inside outer layers of LDPE or LLDPE. In such constructions, the use of UltraGuard is claimed to help minimise the thickness of the HDPE layer needed to achieve the required level of barrier, so minimising the loss of other physical film properties. Milliken says that UltraGuard functions by altering the orientation of the polymer crystals in the film to create a more tortuous path for permeation of molecules. So, in principle, it can be used to improve barrier not only to water, but also to oxygen, carbon dioxide, alcohols, fragrances, and other migratory chemicals. Anti-fog agents are instrumental in maintaining consumer appeal, extending shelf-life and preventing wastage of food packaged in transparent film
16 COMPOUNDING WORLD | January 2022
Renewable sources Palsgaard’s Einar anti-fogs are based entirely on renewable plant sources, which are also widely used in food additives. The company says they are not restricted by any migration limits and have full food-contact, kosher and halal approvals. “Moreover, as they migrate and increase the surface tension of the film, they develop outstanding anti-fog performance even at reduced concentrations, which maximises their cost- efficiency,” according to Ulrik Aunskjær, the company’s Global Industry Director, Non-Food Business Development, Polymer Additives. “We are experiencing a fast-growing demand for our sustainable polymer additives among plastics and masterbatch manufacturers,” says Aunskjær. “As highly effective and renewable solutions, they offer responsible choices to meet strict regular and high-performance requirements especially in ever thinner multi-layer film applications without compromising mechanical and barrier properties.” Einar anti-fogs are derived from polyglycerol
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esters, monoglycerides and other vegetable sources. The portfolio comprises migratory solutions tailored to PE, PP, EVA, and PVC packaging films. Grades are available in pellet, paste and liquid form, enabling dust-free blending in film extrusion compounds and masterbatches. Even the general- purpose paste product Einar 211 has been shown to work well in various types
of PE as well as PVC mono- layer film formulations for both cold-fog and hot-fog applications at recommended loading levels of
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