additives | Functional fillers
Right: This SEM shows the spherical
particle shape resulting from Huber’s new Spherilex
continuous pro- duction process
Manager for Polymers at Imerys. For the past 60 years, precipitated silica has been
HAR 3G T84 and HAR 3G T77 talcs, which are designed to improve strength and stiffness in polyolefin and engineering plastic compounds. The company says that the HAR 3G talcs are milled using a new, patented process. Compared to fine, jetmilled talc, the HAR 3G talc grades are said to be able to improve stiffness by up to 25% while also enhancing dimensional stability and temperature performance. In TPO and PP automotive compounds, the minerals can help designers achieve reduced wall thickness and part weight while achieving zero-gap tolerancing.
Imerys also recently introduced two new JetFil talcs. The JetFil V625C and V7000 talc grades are both produced in North America and are said to provide high lamellarity for improving reinforcing performance at an economical price. The company has expanded capacity at its site in Vermont and invested in new environmen- tally-friendly purification technologies to manufacture the talcs, which are available globally. Last year, Imerys introduced Nicron 674C, a platy, high density, dry compacted microcrystalline talc that is also sourced in North America. This talc is designed for PP and TPO compounds used in packaging, appliance, and automotive applications. Imerys also opened a laboratory for
Right: Film antiblocking is a key
application area for Huber’s Spherilex
silica fillers
testing mineral performance in polymers at San Jose in California, US, in the first half of last year. The lab is now being used to develop data that will enable the company’s development teams to better understand mineral performance in various polymer systems. With develop- ment cycles getting shorter, the aim is to deliver the customised mineral performance required to meet custom- er’s demands more quickly, explains Chris Scarazzo, Market
56 COMPOUNDING WORLD | August 2017
manufactured using a batch process that involves precipitation of silica agglomerates that are then milled to the desired particle size. Huber Engineered Materi- als, a division of JM Huber Corporation, has now developed a continuous manufacturing technology that it claims can produce spherical precipitated silicas and sodium aluminosilicates offering a wide range of porosities and particle characteristics without the need for milling. Huber’s patented Spherilex process yields a product that is said to offer potential advantages for diverse thermoplastic applications including antiblocking, matting and light diffusion. The company’s first commercial production capacity started up in Septem- ber last year at its facility at Hamina in Finland.
Controlled processing In the Spherilex technology, particle characteristics— particle size, particle size distribution and porosity—are controlled by changing reactor processing conditions, says Eric Lundquist, Director of Global Technology for Huber’s Silica business. This results in tight control of both particle size and particle size distribution, which is key for optimising properties in thermoplastic com- pounds.
The ability to control particle size, particle size
distribution and refractive index between 1.44 and 1.58 allows optimisation of the additive to obtain precise film antiblocking characteristics, for example. Antiblock applications require a particle size that is large enough to achieve the surface roughening required to achieve the antiblock effect but small enough not to have a detrimental effect on clarity. In the past, antiblock additives were not typically tailored for specific film gauges. However, the trend towards downgauging and the increasing use of thin multilayer films in packaging, particularly when clarity is important, creates opportunities for the benefits of a tailored particle size, Lundquist says. The Spherilex process can also be used
to control the level of porosity of the silica particles, with surface areas from 1 m2 to 600 m2
/g /g possible. The very high surface
area of a highly porous particle is good for absorption and could support the use of the filler as a carrier, says Lundquist. Lower porosity, on the other hand, could be better for production of silica masterbatches as additives such as slip agents and processing
www.compoundingworld.com
PHOTO: HUBER ENGINEERED MATERIALS
PHOTO: HUBER ENGINEERED MATERIALS
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