Minerals Technologies Inc.

Construction Sealant



Specialty Minerals Precipitated Calcium Carbonates and Mineral Fillers for Construction SealantsSealants are used in many places in and around residential dwellings, as well as in the construction of office, factory, and commercial buildings. For example, sealants fill joints between precast panels and between glass and steel in glass wall curtain buildings. They are also used in factory window glazing and the manufacture of insulating glass windows. The sealants are gap fillers, acting as barriers to moisture, gas, and solid particles.

Resin systems used in manufacturing high-performance construction sealants include silicones, modified silicones (silyl terminated polyethers—STPE), polysulfides, and polyurethanes. Lower-durability sealants and caulks may use an acrylic, vinyl acetate or other water-based polymer, or a butyl rubber. The higher-performance sealants must have long service lives, remaining solid but flexible under many cycles of extreme temperature and humidity. They must also resist ultraviolet light. All this performance must come in an economical package. General-purpose caulks have shorter service lives, and low cost is often the most important factor. Selection of a specific sealant will depend on the end-use conditions for the application.Precipitated Calcium Carbonates in Construction SealantsPrecipitated calcium carbonates (PCCs) are often used as the rheological additive and functional filler in higher-performance construction sealants. Building a true thixotropic, shear-thinning structure in the polymer, PCCs control yield value, sag, slump, and extrusion rates. They are often used as the sole thixotrope or to replace part of the more expensive conventional thickeners. In addition, the nano or ultrafine PCCs reinforce the polymer, increasing tensile strength and modulus. Even though available in uncoated hydrophilic grades, PCCs are seldom used as the rheological additive in general-purpose water-based caulks for the home.Specialty Minerals PCCs for Construction SealantsSpecialty Minerals Inc. (SMI) manufactures a variety of nano and ultrafine PCCs for construction sealants. We have been producing nano PCCs for over 25 years in plants in the U.S. and U.K. They are available for purchase worldwide.Variety in particle size and coatings yields PCCs that work well in the range of polymer types used for construction sealants.The Specialty minerals PCC products recommended for construction sealants are:  Tape joint compounds or cements may be classified as construction sealants or building products. You can click here to read more about SMI minerals for tape joint compounds used with gypsum wallboard.Other Specialty Minerals Minerals for Construction SealantsSMI also produces ground calcium carbonates (GCCs) and talcs in the U.S. Most construction sealants, except for clears, contain GCC as a cost-reducing filler. PCC and GCC work well together; their ratio can be changed to adjust the high-shear viscosity or extrusion rate of the sealant. Talcs—platy, hydrophobic and chemically inert—improve the durability of sealants, especially those using shorter service life, water-based acrylic, vinyl-acrylic, vinyl acetate-ethylene or polyvinyl acetate emulsions. Exterior water-based paints have long used talcs as fillers to improve weatherability, moisture resistance and crack resistance.

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