Specialty Minerals Precipitated Calcium Carbonates and Mineral Fillers for Automotive Sealants
Sealants are applied in all areas of cars, trucks, and buses as seam and gap fillers as well as for sound deadening, corrosion control, and windshield installation. Polyvinyl chloride (PVC) plastisol is the main resin used in OEM automotive sealants, primarily for body-seam sealers and underbody coatings. Other sealant systems for glazing and seam sealing include polyurethanes, silicones, and butyl and other elastomeric rubbers. These sealants must be economical to produce, flexible and rugged enough to perform under extreme conditions over long periods of time. They must also resist ultraviolet light, mechanical stress, and extremes in temperature and humidity.
Precipitated Calcium Carbonates in Automotive Sealants
Ease of application is one of several key attributes of a superior sealant. Ultrafine or nano precipitated calcium carbonates (PCCs) function as cost-effective thixotropes in the various resin systems to ensure easy application. As a shear-thinning rheological additive, PCC provides for ease of pumping, extrusion, or spraying, as well as viscosity, yield value, and control of sag and slump. PCC is an economical alternative to higher priced thixotropes, able to either extend or replace them. The ultrafine and nano PCCs also reinforce the sealant, thereby increasing tensile strength and modulus.
Specialty Minerals Precipitated Calcium Carbonates for Automotive Sealants
Specialty Minerals Inc. (SMI) has manufactured ultrafine and nano PCCs for automotive sealants for more than 25 years. Produced in the U.S. and U.K., they are sold around the world. A number of the products are true nano particles, less than 100 nanometers or 0.1 micron in size.
SMI PCCs vary in size and coating, offering optimized performance in a range of polymer systems.
Specialty minerals PCCs recommended for specific automotive formulations are:
Other SMI Minerals In Automotive Sealants
SMI also produces ground calcium carbonates (GCCs) and talcs that are useful in automotive sealants. GCCs are used as cost-reducing fillers in almost all sealants and work effectively with PCC thixotropes. GCCs add some mildly thixotropic viscosity. Finer GCC grades produce higher viscosity build, while the coarser grades allow for higher loadings and the best economy.
Talcs improve resistance to water and chemicals. While most polymers used in automotive sealant applications already are long-lived, butyl rubber and water-based sealants may further benefit from the addition of talc. Unsaturated polyester auto-body filler putties include talc for sandability and surface finish.
Specialty Minerals Precipitated Calcium Carbonate Product Selector for Sealants
There is a Specialty Minerals Inc. (SMI) nano, ultrafine or fine
precipitated calcium carbonate (PCC) which can improve the rheological,
application and mechanical properties of your sealants. They are widely
used as the thixotrope in a broad spectrum of automotive and
construction products, including acrylic and PVC plastisols,
polysulfides, polyurethanes, silicones and modified silicones, silyl
terminated polyethers, butyl and other elastomerics, as well as in
Precipitated Calcium Carbonate Performance in Sealants
The selector chart below provides general guidelines about which SMI
PCC to use in a particular sealant type and application. To help
understand why a particular PCC should be used, click on one of the
links to read more about them:
PCC basics: types of PCCs (nano, ultrafine, fine, medium) and the functions they impart to sealants, PCC rheological structure and how it is built, why some PCCs are coated, the effect of dispersion work done on efficiency and stability, and how to adjust extrusion rate with the PCC / GCC (ground calcium carbonate) ratio.
PCC properties: effects of particle size, degree of hydrophobicity, equilibrium moisture, degree of shear thinning, and adjusting extrusion rate by changing the PCC used.