Mineral Technologies Mineral TechnologiesMinteqSpecialty Minerals
CareersCorporate ResponsibilityContact UsMSDSSitemapSearch
About SMIOur MineralsPaperSpecialty ApplicationsExhibitionsPublicationsUseful Links
 
STPE - Silyl Terminated Polyether Sealants with Specialty Minerals Precipitated Calcium Carbonates and Other Minerals

Silyl terminated polyethers (STPE) have a strong position in the sealant market in Europe and Japan and are gaining steadily in the U.S. The polymers are also called modified silicones, being polypropylene oxide polyethers which are terminated with hydrolyzable dimethoxysilyl groups. Room temperature curing is achieved using both moisture and a catalyst. STPE sealants combine the good weatherability of silicones with the paintability of polyurethanes, and have excellent adhesion to substrates. Silyl terminated polyethers are also known as MS polymers, a trademark of their manufacturer, Kaneka.

STPE-based products are used for sealing in construction at expansion joints and around windows and doors. They are preferred in sealing to natural stone as they do not stain. In automotive applications, STPE sealants are mainly used in the aftermarket, for body repairs and sealing seams and joints, as well as in the OEM manufacture of recreational vehicles and buses. 

Specialty Minerals Precipitated Calcium Carbonates for Silyl Terminated Polyether Sealants
Formulations for STPE sealants include precipitated calcium carbonates (PCCs) as both the rheological additive and functional filler. Coated PCCs build thixotropic structures in sealants with good yield value, package viscosity and extrudability, rheological stability, and sag and slump control. They can be a total or partial replacement of more expensive thixotropes. PCCs add reinforcement and produce high tear and tensile strengths in the cured sealant. In STPE sealants, PCCs are typically used at loadings of 20 to 50 percent.

For STPE sealants, the Specialty Minerals Inc. (SMI) nano and ultrafine PCC grades recommended are:

  • Thixo-Carb® 500 PCC – the best recommendation for shelf stability in one-part systems. This is the most hydrophobic PCC, with lowest moisture, making it ideal for moisture curing systems. It is a  0.15 micron PCC with a proprietary coating. Thixo-Carb® 500 is often used in moisture curing systems without predrying. Click here to read more about moisture levels. This PCC is manufactured in SMI's plant in Adams, Massachusetts, in the U.S.
  • Calofort® SV PCC – a highly efficient, easy-dispersing nano PCC, at 70 nanometers (0.07 microns). It is stearic acid-coated and is manufactured in SMI’s plant in Birmingham, U.K.
  • Ultra-Pflex® PCC – another efficient, easy-to-disperse nano PCC with high uniformity. It is a true nano particle 70 nanometers (0.07 microns) and is stearic acid-coated and is manufactured in Adams.
  • Calofort® SM PCC – recommended where lower package viscosity and good sag resistance is needed. This PCC is 0.07 microns and is manufactured in Birmingham, U.K.

Click on a product’s name to download the technical data sheet for that product.

Click here to read more about the rheological and reinforcing properties of SMI PCCs and then click here to read about particle size, hydrophobicity, and surface moisture, and how these factors affect the choice of grades for particular sealant types. A PCC/polymer sealant type application selector chart can be viewed by clicking here

SMI Ground Limestones and Dolomites for STPE Sealants
For filling and cost reduction, STPE polymer-based sealants will also typically contain a ground limestone (calcium carbonate) or ground dolomite (calcium magnesium carbonate) to bring up the total solids level. In the U.S, SMI manufactures both ground calcium carbonates (GCCs) and ground dolomites. GCCs are produced in Adams, Massachusetts and Lucerne Valley, California, and are sold under the trade names Vicron®, Marblewhite® and RiverCal™ GCCs. The ground dolomites, manufactured in Canaan, Connecticut, are sold under the trade name Dolocron® dolomite.

Click here to read more about the SMI ground carbonates used in sealants.

 

Learn more: