IMPACT MODIFIERS | ADDITIVES
A major problem in applying these materials is the need to compensate for the loss of properties of virgin resins and to compatibilise the plastic blends, according to the company. New impact modification solutions can assist in compatibilisa- tion. Other technical challenges include developing solutions for adjusting the rheology of recycled plastics for efficient processing — injection mould- ing and extrusion require quite different rheologies. A further issue is improving mechanical proper-
ties, such as tensile strength, impact strength and elongation at break. In lightweight solutions, the company says use of glass fibres is particularly important but so is a good coupling agent to provide the right properties. It offers a wide range of coupling agents for compounds filled with mineral, inorganic and organic materials, including its Lotryl copolymers, Lotader reactive resins and Orevac grafted polyolefins. SK offers viscosity and impact modifiers for use
with styrenic compounds such as ABS and HIPS, as well as PA, thermoplastic polyesters and PPS. Lotryl 28BA700T can lower viscosity and increase impact strength in ABS resins, while Lotader AX8900 is used to decrease ABS fluidity and increase impact strength. Lotryl 29MA03T is an ethylene-methyl acrylate copolymer with high acrylate concentra- tion, which significantly improves impact strength of ABS and HIPS while maintaining fluidity. The company says it is working on increasing the
limits of impact and viscosity modification in plastics, as well as compatibilisation of blends of resins that are difficult to separate, such as recy- clate from PE/EVOH/PET structures. This combina- tion of incompatible resins is widely used in the packaging films industry.
Packaging change Packaging is an interesting and growing area in terms of impact modification, according to Milliken, which it attributes to a combination of the increasing role of online shopping. “The main trends and influences driving new developments in impact modification for plastic compounds include the growth of e-commerce supply chains, which demand robust packaging,” says Katie Kellogg,
Functional monomer content Melting point
Melt index (190°C/2.16kg) Source: SK Functional Polymer
www.compoundingworld.com April 2023 | COMPOUNDING WORLD 59
Lotader AX8900 24% MA 8% GMA 65 6
I LL I
M : E G A
Left: Max-
Impact impact modifiers from Milliken improve the impact
performance of clarified PP for low tempera- ture packaging applications
Global Product Line Manager MaxImpact. “There are also regulations around food waste
that may require frozen or more processed foods to reach customers. Additionally, there is a shift towards replacing less sustainable materials with polypropylene, which is recyclable and can be enhanced with impact modifiers to replace harder to recycle materials,” she says. Kellog identifies a trend to improve impact performance of clarified PP materials. “This will enhance product durability, enable the replace- ment of less-recyclable materials with impact-modi- fied PP, and provide better optics than previous solutions. These technical areas are being ad- dressed through ongoing research and develop- ment to create more effective impact modifiers for clarified PP,” she says. Milliken says its MaxImpact impact modifiers are a good solution for clarified PP applications. It says while PP is one of the most versatile, recyclable and functional plastics available, one of its shortcom- ings is impact performance at very low tempera- tures. With e-commerce booming, it says high- impact, cold-temperature-resistant plastics are in strong demand to limit issues around container breakage during transport and use. The company says its MaxImpact impact modifier provides a good balance of impact resistance, clarity and stiffness in PP applications, broadening the resin’s application to products that are currently produced in PS, PET, or PETG. It has been designed for use by injection moulders, thermoformers, blow moulders and extruders. Using the Gardner Impact ASTM test’s Bruceton Staircase Method, Milliken says researchers have
Typical characteristics of Lotader AX8900, Lotryl 28BA700T and Lotryl 29MA03T Characteristics Acrylate content
Lotryl 28BA700T 28% BA /
94 700
93 3
Lotryl 29MA03T 29% MA /
Unit wt.% wt.% °C
g/10min
NE K
M I
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