masterbatch feature | Carrier materials


shown in Figure 1. It therefore also increases the impact resistance of filled polymers, as shown in Figure 2. Good dispersion also allows lower additive loadings to have the same level of effectiveness as higher loadings, which reduces formulation cost, according the company. Compared to other types of EMA resins, Elvaloy AC


FIGURE 1: IMPROVED FILLER DISPERSION WITH ELVALOY 1820AC (RIGHT) COMPARED TO USING A PE CARRIER (LEFT)


products have higher melting temperatures (around 90°C), which leads to less sticking in the feed hopper, says DuPont. Elvaloy AC (EMA) also has higher thermal stability than EVA; its upper processing temperature is 320°C, compared to 230°C for EVA resins. ExxonMobil’s Vistamaxx elastomers are semi-crys-


talline copolymers of propylene and ethylene produced using the company’s Exxpol metallocene catalyst technology. Vistamaxx is used for a variety of applica- tions, including as a carrier resin, in which it is compatible with a wide range of polyolefins. The resin’s high ethylene content makes it compatible with both PE and PP, explains Maenza. Due to its unique product morphology, Vistamaxx has


a very narrow molecular weight distribution and high heat stability. In masterbatches, these properties allow a broader processing window in various types of compounding machines with higher filler acceptance and improved dispersion of pigments and fillers, says the company. High filler acceptance is particularly important, for


example, in CaCO3-based filler masterbatches for the raffia and shopper bags industry and in sophisticated


FIGURE 2: ELVALOY DELIVERS INCREASED IMPACT STRENGTH FOR FILLED


COMPOUNDS (PA 6 WITH 5 WT% TIO2 MASTERBATCH CONTAINING 60 WT% OF DUPONT R-104 TIO2)


bil Chemical. High filler levels are being used in white masterbatch compounds, in which there is an increas- ing use of cheaper fillers such as CaCO3 white TiO2


blended with pigment to reduce overall cost, adds Maenza. Suppliers continue their quest for appropriate


universal and low-flow carriers that have good disper- sion for higher loading levels, and they have introduced many new developments. For example, DuPont’s Elvaloy AC products are ethylene acrylate copolymers, includ- ing ethylene methyl acrylate (EMA) and ethylene butyl acrylate (EBA). Elvaloy AC products have good compat- ibility with both non-polar and polar polymers such as PE, PP, PA, PET, PBT, PC, ABS, and PVC. They also have broad compatibility with polar and non-polar fillers and additives, such as those used to improve toughness and stress crack resistance. Using Elvaloy AC products as carrier resins permits higher filler loadings and improves filler dispersion, as


18 COMPOUNDING WORLD | August 2012


functional and colour masterbatches for foaming, flame retardant and spun-bond non-woven applications. Vistamaxx can accept up to 85% calcium carbonate loading. “For monofilaments used in woven bags, Vistamaxx


provides better anti-fibrillation performance, less yarn breakage and fewer dusting problems,” says Maenza. In pipe applications, Vistamaxx can allow high filler loadings while maintaining flexibility. At higher masterbatch ratios, Vistamaxx can also yield improved tear and impact properties for films and enhanced weld line and impact strength for blow moulded containers. Vistamaxx’s low melt temperature compared to LLDPE and PP allows it to be compounded at lower temperatures, which saves energy and reduces the potential for thermal degradation. It also allows it to serve as a carrier for heat-sensitive additives such as blowing agents or flame retardants, the company reported at AMI’s Masterbatch conference in Singapore earlier this year. Clariant is also taking advantage of the ability of


metallocene catalysts to control the molecular weight distribution and optimize the flow properties of


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