additives feature | Antioxidants Marshall notes that as new generations of polymers
are developed with improved mechanical properties for use in new and demanding applications it is increasingly important that stabiliser systems are able to protect the polymer for longer in more demanding environments and under different processing conditions. “In some instances this can be done by merely increasing the amount of stabiliser in the polymer but, whether due to constraints such as additive solubility or regulatory requirements, this approach has its limitations,” he says. Marshall highlights Everspring Chemical (Taiwan)’s new highly reactive dialkyl hydroxylamine stabiliser, Everstab FS042, which can be used in synergistic blends with more traditional antioxidants and stabilisers in polyethylenes and polypropylenes. Like all dialkyl hydroxylamines, Everstab FS042 is a catalytic chain- breaking antioxidant. “This means that the antioxidant is regenerated rather than consumed in the
stabilisation process and so it is very effective even at lower addition levels than other chain-breaking antioxidants,” Marshall says. It is used in combination with other stabilisers either to boost the effi cacy of the system or to achieve the same level of stability with a reduced total stabiliser loading.
Mayzo is expanding its line of thermal and UV stabiliser products with the addition of BLX 2811 and BNX 2301, both also based on hydroxylamine chemistry. BNX 2301 is a process stabiliser designed to provide outstanding processing stability in polyolefi n applications. The company describes it as “an excellent choice to improve performance compared to standard systems based on phenolic and phosphite chemistries.” Unlike phenolic antioxidants, Mayzo says the hydroxylamine does not form conjugated by-products that can lead to colour development. Recommended applications include polypropylene fi bres, sheet and profi les, HDPE fi lms and
HDPE stabilised with Everstab FS042 compared to traditional hindered phenol and phosphite antioxidant systems. The HDPE is cross-linking during multiple extrusion at 240°C. The blank is HDPE containing no stabilisers, the 0.12% Everstab B210 sample contains 0.8% Everfos 168 + 0.4% Evernox 10, the 0.08% Everstab ES-A sample 0.049% Everfos 168 + 0.026% Evernox 10 + 0.005% Everstab Fs042
colour-critical TPO applications.
In addition to process stability, the BLX 2811 grade includes light stabilisation and long term thermal stabilisation functionalities. The product is said to provide a complete stabilisation system targeted at polyolefi ns, TPO and TPE applications.
Dover Chemical Corp has just received FDA clearance for its Doverphos LGP-11 high molecular weight liquid phosphite antioxidant for as a thermal stabiliser in single- and repeated-use linear low density polyethylene (LLDPE) fi lms and high density polyethylene (HDPE) articles in contact with all food types under Conditions of Use A through H. It covers loading levels up to 2000 ppm.
The company says Doverphos LGP-11 is intended as an alternative to TNPP or any other phosphite additive in any polyolefi n application. It can also be used in SBS, SBR, urethanes and PVC. The additive contains no alkylphenol components and is composed of biodegradable raw materials.
“The fact that LGP 11 is not produced from
alkylphenols provides benefi ts that are unprecedented by any other phosphite on the market today,” says Mick Jakupca, director of R&D. “Most antioxidants are composed of or contain alkylphenols. Alkylphenols, as a general class of chemicals, are a focus of both consumer and regulatory organisations.”
Matthew Fender, business manager of polymer Source: Cytec 42 COMPOUNDING WORLD | September 2015
additives, adds: “We strongly believe this new platform of liquid green chemistry is a paradigm leap forward for the future of antioxidant systems for all polymers globally.”
www.compoundingworld.com
Source: Everstab
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