additives | Functional fillers
Right: Inside the Minerals
Technologies’s production facility at
Lucerne Valley
process reviews these technologies as well as seeking to improve current mineral performance,” he says. “Current compounding equipment needs to provide
adequate dispersion of the functional fillers to optimise their reinforcing and processing benefits in a polymer matrix,” says Wernett. “Functional filler selection can significantly impact die scrub, wear on machinery, and throughput through improving the thermal conductivity of the mineral-polymer composite. Working with a supplier that has applications knowledge and expertise in plastics can offer compounders significant value in selecting the optimal mineral products for final part performance and meeting the processing equipment needs.” Specialty Minerals offers a range of filler products
customised to meet specific challenges in the plastics compounding industry. “We are currently working on higher efficiency fillers for lightweighting, balancing property improvement and loading to optimise end use applications,” Wernett says. “We continue to seek improved functional fillers that enhance physical properties and compound stability.”
Hematite – a new filler Manufacturer and supplier of minerals, fillers and extenders Kish Company is introducing a number of new products for the plastics industry, including an iron oxide filler. The company has just completed the first milling of the DenzFlex product. “Currently, the only iron oxide available on the market is magnetite,” says Dr Chris DeArmitt at the company. “DenzFlex is manufactured from hematite, which offers the same density and hardness as magnetite but is a totally different mineral with different properties. It has the same density as magnetite – 5.2g/cm3
– but almost
Below: Mining talc at Mineral Technologies’ Barretts operation
double the thermal conductivity at 12.5W/cm/K. So while it can also be used for applications requiring density, such as sound damping and radiation shielding, it is also microwaveable. We see new applications for this filler in plastics for microwave heating.”
Hematite is a naturally occurring iron oxide mined
from many deposits worldwide. Although primarily used to make iron and steel, the properties of hematite make it suitable for other applications, including as a filler for plastics. While hematite is common, it has not been used as a filler before because an extremely pure material is needed. It shares several features with magnetite, but DeArmitt believes that hematite filler may well prove to be a more cost-effective option in certain parts of the world. Hematite filler can be used to add mass in various
plastics, such as polypropylene, polyamides and polyethylene. Weight can be useful to impart a high quality feeling to a material or for sound damping. Loadings of 80wt% can be achieved giving compound densities of around 3.0 g/cm3
. Hematite can also be
used as pigment where it can impart an attractive grey metallic sparkle. It also has both magnetic and electrical properties, while its high density makes it x-ray opaque. Hematite filler can be employed to make plastics detectable, for use in medical applications, food processing and for anti-counterfeiting. Hematite can also be added to polymers to allow
them to be heated either by microwaves or using induction. Typically, plastics are microwave transparent and, because they are electrical insulators without any magnetic properties, do not heat by induction. Hematite heats up very quickly in a microwave oven, approximate- ly 200°C per minute in a standard domestic oven. While the pure material heats extremely quickly in a micro- wave, when used as a filler in a plastic this heating capa- bility can be tuned to what is required, according to DeArmitt. There are applications requiring heat transfer where hematite’s high heat conductivity could make it an attractive, low cost, speciality filler option. Kish Company has also developed a low moisture talc
filler. “When you mill talc and it is exposed to the air, it picks up water,” explains Dr DeArmitt. “We have been
16 COMPOUNDING WORLD | August 2016
www.compoundingworld.com
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