Carrier materials | masterbatch feature
The long-running search for the perfect carrier material continues. Jennifer Markarian looks at the latest developments for colour and additive masterbatches, as well as innovative porous carriers for liquids
Developments in masterbatch and additive carrier materials
Carrier polymers, which play the humble role of carrying the colorants or additives in a concentrate or master- batch, need to blend easily into the base polymer to help disperse the pigment or additive. In addition, they should have minimal effect on the end-product’s physical properties. Some ‘universal’ carriers are compatible with several different base or matrix polymers, while other carriers target a specific base polymer. Universal carriers are desirable for minimizing
inventory. Typical universal carrier resins include low molecular weight, high-flow, low-density polyethylene (LDPE), ethylene vinyl acetate copolymer (EVA), and low molecular weight PE or polypropylene (PP) waxes. While universal carriers can go into a range of PE types, the extent of their compatibility in other resins may depend on the application, notes Prakash Patel, senior technical director at masterbatch producer Ampacet. For example, universal carriers will work in a thick PP part that has 1-2% masterbatch, but may have a negative effect on the properties of a PP film, fibre, or thin part, in which the relative contribution of carrier resin is higher. Formulators are still searching for the elusive
polymer that is truly compatible across multiple resin families, says Patel. Finding the optimal viscosity is a
www.compoundingworld.com “
Formulators are still searching for the elusive polymer that is truly compatible across multiple resin families
PRAKASH PATEL, AMPACET ”
balancing act, he adds. Lower viscosities flow easily, but if the viscosity is too low it will not develop enough shear to disperse during masterbatch production, and may degrade properties of the end part. In addition to better universal carriers, an ongoing
request from masterbatch producers is for carriers that can hold higher levels of pigment or additive. This is because high loadings, which use less carrier resin, are more cost-effective for the processor. Titanium dioxide, for example, can already be loaded at the highest possible level (just over 80% empirical limit based on surface area), but the loading levels of organic pigments are limited by dispersion issues, says Patel. Improved dispersion of nano-size fillers is another
industry requirement, notes Lynell Maenza, Asia Pacific market manager for specialty elastomers at ExxonMo-
August 2012 | COMPOUNDING WORLD 17
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