ADDITIVES | ANTIOXIDANTS AND STABILISERS
Right: New technology from Solvay improves resistance of polyolefins to UV-C radiation used for surface sterilisation
containers/packaging, hospitality, retail, public building among others.” Landuzzi says the new stabilisation technology is
an important milestone for the polyolefin industry. “It is the first to address the risk of polymer degra- dation, discoloration and micro-crack formation, which is caused by frequent exposure to UV-C irradiation,” he claims. Parts regularly disinfected using UV-C light,
Below: Comparison of the effect of UV-C radiation on PP with and without Solvay’s new stabiliser (tests carried out using a low pressure Hg lamp, 254nm; irradiance 1200µW/cm2
)
require a special stabilisation solution in order to retain durability and function. UV-C radiation possesses much higher energy than UV-A and UV-B and can damage materials through a number of chemical reaction mechanisms. It is not said to be a concern in general stabilisation systems as the ozone in the earth’s atmosphere prevents UV-C radiation reaching the planet surface, whereas UV-A and UV-B get through. “Today, plastic articles and surfaces are not typically formulated with long-term UV-C exposure in mind and can start to discolour and crack when exposed to UV-C irradiation,” Landuzzi says. “Specific knowledge and expertise in UV-C stabilisation is required in order to sufficiently protect a polymer system from degradation.” Traditional mainstream stabilisers that protect polymers against UV-A and UV-B irradiation (in the range 280-400nm) have been shown to be ineffective in stabilising high-energy UV-C irradiation, he says. “By incorporating Solvay’s UV-C stabiliser into the polymeric materials, protection against UV-C degradation can be achieved,” Landuzzi says. “This new stabilisation technology provides superior durability after extensive UV-C exposure, excellent colour stability in a high-energy UV-C environment, extends the lifetime of UV-C exposed material, protects physical properties after UV-C irradiation and offers superior surface protection of natural and pigmented polymeric parts.”
High performance HALS Hindered amine light stabilisers (HALS) are widely used to extend the lifetime of plastics products, especially in outdoor applications. Adeka, a major HALS developer and supplier, has been especially active in automotive applications but says with the increasing interest in sustainability across markets, high performance HALS solutions are also finding greater use in applications such as roofing mem- branes, agricultural films, artificial turf and ge- omembranes.
“In these applications, existing solutions for light stability are available but often their performance is not enough to meet the latest trends in the market for demand of increased performance,” according to the company. “Recently, for example, demand for increased UV resistance of TPO roofing from 10- 15 years to 20-25 years has meant that a higher performance than current conventional triazine type HALS is required.” Adeka says this high durability requirement can be met using its ADK Stab LA-704AF stabiliser. Under testing conditions typically applied for TPO roofing applications, the additive demonstrated what the company describes as “excellent perfor- mance”. It is said to show superior weatherability and heat stability compared to the conventional triazine type HALS used as reference in its tests. “Furthermore, it was possible to maintain performance under even more stringent weather- ing conditions (>20,000kJ/m2 with spray) and oven test (120o
at 340nm, BPT=65o C, >32 weeks) than
ASTM D6878 and it significantly outperformed the conventional triazine type HALS reference in these tests,” Adeka claims (Figure 3). The company says ADK Stab LA-704AF main- tained its high performance even under exposure to external stress (bending test) after weathering in a test representative of actual use for a TPO roofing membrane. “ADK Stab LA-704AF therefore offers
68 COMPOUNDING WORLD | September 2022
www.compoundingworld.com
C,
IMAGE: SOLVAY
IMAGE: SOLVAY
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