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Functionalized Silica Fillers for Advance Applications

Donald Rosato – Mar 15, 2018

Advances in Functionalized Silica FillersPlastic resins are compounded with a wide variety of mineral fillers. Most mineral fillers have served an important cost reducing role by replacing the more expensive resin in a given compound. However, major suppliers in the silica-based talc filler segment have made great strides in offering functionalized recently. These fillers enhance key plastic properties, such as: Flexural, stiffness and impact strength.

Key functional filler suppliers are expanding capacity and improving their filler manufacturing process technology. The overall silica fillers market is growing on an average at 5% annually and is being led by these cost-effective functionalized fillers.

These functionalized fillers are being used in a broad range of applications that include anti-blocking transparent films, improved flow plastic compounds, LEDs, and 3D printing.

Want to know more about silica-based talc? Find out here!

Learn the latest advances in micronized talc and the new silica process manufacturing technology, providing a range of particle sizes for application development purposes.


Significant Features of Silica-based Talc


Talc comes from earth mining with different type deposits yielding materials based on a given platelet size with their own unique property profiles. With further proprietary processing, talc fillers are tailored to meet specific compounded plastic properties.

Raw Mined Outdoor Talc Operations
Raw Mined Outdoor Talc Operations
Plastics Institute of America


Thermoplastics have historically used silica-based talc as reinforcement. It exhibits a strong machine direction reinforcing capability due to its plate-like structure, typical of anisotropic materials.

 − Like wood that is strong along the grain, talc is robust along its plate structure but weaker in its cross direction.
 − Also, talc shows reduced warping accompanied by good mechanical properties.
 − Further, its non-wetting, hydrophobic nature allows for easy dispersion in a broad range of plastic resins.

No wetting or dispersing agents are required in silica-based talc. However, flowability is a challenge in talc compounding due to its plate-like structure.

Additionally, talc appears fluffy or fleecy in appearance. This compounding challenge is most apparent in engineered, small particle size talc grades that further exhibit narrower particle size ranges. Further talc compaction prior to feeding into the polymer melt will counter this obstacle. Specialized material handling and feeding device equipment is the key here.

Electron Microscope Image of Talc Plates
Electron Microscope Image of Talc Plates Shows Reinforcing Property Structure


Micronized Talc Advances


#1. IMI Fabi's Specialty Product Range


HTP1s Talc Grade


Italian supplier IMI Fabi has an extremely micronized commercial HTP1s talc grade. It increases HTP1s flowability through a bulk density increase by a factor of 2.5 versus standard loose powder and compacted talc.

 − It accomplishes this flow improvement via compacting talc into sphere-shaped particles.
 − This HTP1s talc grade shape makes it in essence frictionless while flowing and is maintained throughout the blending process with the plastic resin. With this uniform flowability HTP1s assists in allowing all additives to attain very uniform levels at the compound formulation stage.
 − Also, HTP1s can be used in powder based dryblend compounds due to its excellent dispersibility.

IMI Fabis Micronized Talc Grades
IMI Fabi’s Micronized Talc Grades: Loose Powder Talc HPT1 (L), Compacted Talc HPT1c (C), Free Flowing Talc HPT1s (R)

HVTultraC


 − The HVTultraC grade is focused on automotive applications, such as: Dashboards and bumpers, as well as other industrial scratch resistant applications.
 − It has a tailored stiffness to impact capability in thermoplastic polyolefin (TPO) compounds, combining enhanced stiffness to dimensional balance with improved low-temperature brittle break performance.
 − Beyond TPO use, HVTultraC works in a similar fashion with established automotive engineering plastics, such as: PolyButylene Terephthalate (PBT) and PolyAmide 66 (PA 66, or nylon).


NB240


Elsewhere, application development wise; the NB240 talc grade finds use in PolyEthylene (PE) film. It provides extrusion slip performance and lower barrel and screw wear, along with anti-blocking and transparency features.



#2. Imerys High Aspect Ratio (HAR) 3G Talc Products


Continuing, Imerys Performance Additives has commercialized unique High Aspect Ratio (HAR) talc products namely, HAR® 3G T84 and HAR® 3G T77.

Two talc products, HAR® 3G T84 and HAR® 3G T77 are specialty milled via a patented process that improve automotive PolyPropylene (PP) and Thermoplastic PolyOlefin (TPO) compounds.

Property enhancements include improved stiffness up to 30%, dimensional control, and temperature aging. Further, these HAR 3G grades will reduce automotive part weights and wall thicknesses that in turn translate into tighter vehicle fit and finish tolerances.


Imerys' Other Developments


 − In terms of more cost-effective talcs, Imerys offers two JetFil® grades namely, V625C  and V7000 with high platelet counts to maximize reinforcement strength.

 − In addition, it has also developed a densified and compacted Nicron™ 674C talc grade. It will find use in PP and TPO compounds targeted at appliance and packaging end-uses, as well as automotive markets.
Imerys’ HAR Talc Performance
Imerys’ HAR (Dark Green) Talc Performance, 
20% Loading in PP Copolymer


#3. HPF The Mineral Engineer's Functionalized Silica-based Materials


The Quarzwerke Group’s division, HPF The Mineral Engineers, has been doing early development work on functionalized silica-based materials, such as mica and wollastonite for 3D printing Acrylonitrile Butadiene Styrene (ABS) compounds. The goal here is to improve processing speed, stiffness, and surface quality in FDM (Fused Deposition Modeling) and its complementary FFF (Fused Filament Fabrication) 3D printing technologies.
HPFs Functionalized Silica Fillers
HPF’s Mica Mineral Filler (L), 3D Printing ABS Filaments (C), FDM 3 D Printing Process (R)


HPF is experimenting with a range of silica-based particle sizes and shapes. Using silica-based fillers can significantly decrease warpage in finished 3D printed plastic parts.

 − HPF’s work with their functionalized silica fillers involves milling processing to not only vary particle shapes and sizes, but also surface modifying to the point of offering silica coating products. Uniform silica grain sizes need to be in sync with FDM (or Arburg’s FFF) filament die diameters.

 − Another key to this research is to see if HPF silica variants can be improved to strengthen 3D printing layer to layer adhesion to increase mechanical strength properties.

Historically, 3D printable resin systems drop off a third in properties due to their current layer to layer adhesion strengths. Beyond ABS resin work, HPF is working with Polyamide 6 (PA6. Or nylon 6) and renewable content PolyLactic Acid (PLA) resins.


 » Continue reading to explore the new silica process manufacturing technology delivering a range of particle sizes for application development purposes. Also, find out the latest improvements in glass microspheres. 


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