Precipitated calcium carbonate is used in several types of plastics as a highly effective impact modifier, rheology control agent and filler. Because it is chemically produced under strict process control, all aspects of the particle size distribution (psd) and particle morphology (shape) are controlled to exacting specifications.
For carbonates with the same median particle size, the ground calcium carbonate (GCC) has a broader psd than that of the precipitated form. Particle size distribution plots of a PCC and a GCC, each 0.7 microns in median size, show the steeper curve for the PCC, with its narrow distribution.
In these side-by-side photographs of the PCC and GCC of the psd curves, you can see how the PCC particles are all about the same size—very uniform, while the GCC particles are not. The GCC has many large particles and many very small particles. The narrow particle size distribution typical of PCC has many advantages, especially where high impact strength is needed. Click on the link below to learn more about the Fundamentals of Impact and the role particle size distribution plays.
Specialty Minerals PCCs for Plastics
For the plastics industry, Specialty Minerals Inc. (SMI) produces three types of precipitated calcium carbonate products with median particle sizes that range from 0.07 microns, a nano particle, to 2.0 microns.
One type is the ultrafine, nano PCC—70 nanometers or 0.07 microns in size. The nano grades manufactured in the U.K. are Calofort® S, SV and SM coated PCCs, and Calofort® U uncoated PCC. The U.S. grades are the coated Ultra-Pflex® PCC and uncoated Multifex-MM® PCC. This is a scanning electron micrograph (SEM) of a nano PPC.
Two fine-coated PCCs for plastics are Tuffgard® PCC, 0.35 microns, and Super-Pflex® 100 and 200 PCC, 0.7 microns. Albafil® PCC, which is uncoated also find uses in some polymer systems.
The third type is the high surface area scalenohedral (starburst shaped) PCC. Albacar® 5970 PCC made in the U.S., and Calopake® 5970 PCC made in the U.K are examples. Both are only available uncoated.
Precipitated Calcium Carbonates (PCCs) for Rigid PVC
The ultrafine, nano PCCs and fine PCCs are used in rigid polyvinyl chloride applications such as
- PVC siding
- PVC window and door profiles
- PVC pipe and fittings
- PVC fencing and decking
In the rigid PVC applications, the coated fine and ultrafine PCCs can replace more expensive impact modifier, improving the economics of the rigid PVC formulation. Besides providing improved impact, the small particle PCCs yield a product with an excellent surface gloss and finish.
Precipitated Calcium Carbonates (PCCs) for Unsaturated Polyesters
The fine uncoated Albafil®, Calofort® U and Multifex-MM® PCCs are used in polyester gel coats for rheology and gloss. The high surface area and high oil absorption of the scalenohedral Albacar® and Calopake® PCCs build viscosity in unsaturated polyesters, such as sheet molding compounds (SMC) and bulk molding compounds (BMC).
- Specialty applications for SMI products
- SMI minerals for plastics
- SMI minerals for rigid PVC
- SMI minerals for unsaturated polyesters
- SMI minerals Used in Automotive Parts
- SMI minerals Used in Housing and Construction Materials
- About Specialty Minerals Inc.
- Specialty Minerals Plant Locations and Profiles
- What is Precipitated Calcium Carbonate?
- What is Nano Precipitated Calcium Carbonate?