additives feature | Mineral fi llers
Imerys is looking at ways of expanding the use of its various mineral fi llers beyond conventional markets
form of platelets and not spherical like synthetic fi llers. As a result, UltraCarb produces extremely stable charring. UltraCarb, in fact, has a three-stage FR mechanism
geared to temperature. Grades release water at around 220°C (428°F); at about 330°C (626°F), they release CO2
;
and when the temperature is near 560°C (1,040°F), fi ller particles accumulate and form a cementitious char that inhibits combustion and prevents the spread of fi re by burning droplets.
LKAB supplies 10 grades of fi llers based on particle size and the primary blend mineral. Some are also coated, with stearic acid or an undisclosed proprietary material, to improve processing. The grades include LH3, a 1.5 micron (D50
) particle
LKAB researchers are developing mica fi llers that will compete with talc in performance and cost
size and high hydromagnesite (endothermic) loading; 1250, a 2.6 micron (D50
) particle with a high huntite component; and LH15, also a 3.0 micron (D50
(for charring and CO2 (D50
) particle but with a high hydro-
magnesite component. The company is working with other mineral fi llers as
well. One program involves the development of mica with fi ne particle size and a higher aspect ratio (in the
) particle and high huntite ratio properties); 1290, a 3.0 micron
range of 80 to 120) than talc. Viering says that the new mica grades, which are still in testing, will be more economical to use than talc, provide greater warpage control in parts, and be compatible with glass-fi bre reinforcements. LKAB is also conditioning magnetite for use as a
fi ller in polymer compounds. The grade, MagniF, is a high-density material (5.2 g/cm3
) that is used for sound
and vibration damping in automotive and other applications. Viering says it is more economical to use than barium sulphate, which is also a heavy fi ller but, with lower density than magnetite, must be used at higher loadings for similar performance. One likely market for MagniF in Europe is in polymer
components such as rollers for food processing and handling equipment. The mineral was recently certifi ed for food contact by European regulators, and will replace hematite. The permanent magnetic properties of magnetite mean that if any polymer components with the fi ller deteriorate and pieces contaminate food, they will be detected. Polymers have for some time been replacing stainless steel in food machinery. The FDA has certifi ed MagniF for food-contact use in the US. Imerys, which supplies various mineral fi llers, is
looking at ways of expanding their use beyond conven- tional markets. Among the materials and applications under consideration for this is mica, whose sound- absorption properties could result in greater use in automotive compounds. Mica also provides char strength in polymers, increasing fi re resistance and smoke suppression. Diatomaceous earth, which Imerys currently supplies as an anti-blocking agent in polyolefi n fi lm, has value as a blending and mixing agent, as a carrier for other materials within polymers, and in reinforcement. When fl ash-calcined, kaolins can be used as titanium
dioxide extenders, since they provide good light-scatter- ing properties and increase opacity. Imerys supplies calcined kaolins for poly-tunnels – hothouses made of
46 COMPOUNDING WORLD | August 2013
www.compoundingworld.com
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