ADDITIVES | ANTIOXIDANTS
Figure 2: Tensile strength and haze performance of Adeka’s LA-811 stabilisation technology in PE films after high sulphur fumigation exposure
complex chain reactions that lead to polymer degradation caused by UV radiation, and disrupt the reaction cascade. “Standard light stabilisation solutions are not effective under these challenging conditions due to their limited resistance to agrochemicals, elemental sulphur and disinfection products,” Bach says.
Below: AddWorks PKG 906 Circle stabiliser is intended to ease recycling in polyolefin film manufac- turing
Agricultural challenge Italian additives supplier SABO has put consider- able effort into developing new light stabilisation solutions for films. This March, it reported that, after six years of development including accelerated weathering tests and extended field trials in Southern Italy and Northern Africa, it has now added SABO STAB UV 216 to its portfolio of light stabilisers. The company says SABO STAB UV 216 has been shown to provide “outstanding” thermal and UV protection to greenhouse films with proven resistance to agrochemicals, ensuring two or more years lifetime even in the presence of high concen- trations of sulphur. “SABO STAB UV 216 exceeds the pesticide resistance achieved by SABO STAB UV 119, the well-known HALS broadly used to
Source: Adeka
stabilise PE-based greenhouse covers,” says the company. Korean company Songwon, which has a long-term collaboration with SABO, says that under a distribution agreement it will promote SAB- OSTAB UV 216 “by building on the unique combi- nation of SABO expertise and strong in-the-field support from Songwon’s Technical Service, Global Application Community and highly experienced sales team.” Alberto Vischetti, Global Head of SABO’s Plastic Additives BU, says the additive “takes us a further step forward in our journey to establish a global presence for light stabilisers.” Adeka has also been tackling the sulphur
problem, which it says has been become more urgent in recent years as the concentration of sulphur fumigation has increased. Noting that the acidic nature of the sulphur species absorbed in the film interacts with the basic amine stabiliser, effectively neutralising the function of the additive through salt formation, it says it has developed and launched ADK Stab LA-811 as a solution. The product is said to provide high weatherability even under high sulphur fumigation conditions. “For sulphur-resistance, typically low-basicity
N-Alkoxy HALS are used as these practically do not form salts with acidic species arising from sulphur fumigation,” a company spokesperson says. “To cope with the increase of the concentration of sulphur, it is necessary to increase the amount of N-Alkoxy HALS added in order to maintain suffi- cient weatherability, but this can lead to issues of migration of the HALS. ADK Stab LA-811 can demonstrate high performance at low concentra- tion even under high-sulphur fumigation. In particular, it is possible to maintain physical properties and transparency at this low loading after exposure and is superior to conventional light stabiliser solutions.”
86 COMPOUNDING WORLD | September 2019
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www.compoundingworld.com
PHOTO: CLARIANT
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