03 Nov 2022
Technical Control Water-based Thickener
November 3, 2022
Rheology additives not only increase the viscosity of the coatings, and improve the storage stability, but also prevent the occurrence of sagging during the construction process, and can also endow the coating film with better mechanical properties. It is a very important additive for waterborne coatings.
There are many kinds of thickeners on the market, which are mainly divided into four categories: Inorganic, Cellulose, Polyacrylates and Associative Polyurethane Thickeners. Among them, Polyurethane Thickener is a newly developed Associative Thickener in recent years.
The associative structure is destroyed under the shearing force, which results in a decrease of viscosity, and when the shearing force disappears, the viscosity recovers, which prevents sagging during construction. The viscosity of coatings has a certain hysteresis in the recovery timing, which is beneficial to the leveling of the coating. The relative molecular weight of polyurethane thickeners (from thousands to ten thousand) is much lower than the Inorganic and Cellulose Thickener (from hundred thousand to millions), which is not conducive to splash resistance. The molecule of polyurethane thickener has both hydrophilic group and hydrophobic group. The hydrophobic group has strong compatibility with the coating base materials and that could enhance the water resistance of the coating.
PT-66 and PT-67 has an excellent balance of thickening, and leveling, and does not affect gloss. Other types of thickeners such as cellulosic thickeners to obtain similar properties at the same time. It is featured excellent compatibility with ionic and non-ionic emulsions without affecting the water resistance of the paint film.
PT-20 – Waterborne high shear nonionic associative leveling waterborne polyurethane thickener. It not only has high shear viscosity thickening effect, but also its thickening system has fluidity and leveling properties, and its rheological properties are close to Newtonian fluid type, especially suitable for water-based rheology, leveling and thickening effects that require high requirements at the same time. system.
Added at the grinding or paint mixing stage. Recommended 0.5 – 2% based on total formulation. The
actual amount should be determined according to different formulas and viscosity requirements
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