Formulation design system for waterborne coatings - rheological auxiliaries

2019-07-16

Rheological AIDS provide a leveling effect under high shear conditions, allowing the painted fluid to level out as quickly as possible, reducing brush marks and avoiding spatter. However, as the drying time goes by, this leveling effect weakens and the film is fixed, which can prevent the fluid from sagging on the vertical surface.
Rheological additives can be divided into high, medium and low shear viscosity types: low shear viscosity rheological additives can provide viscosity inside the tank, prevent pigment settling, and effectively control the paint liquid in the standing Snails generated during surface operations; rheological additives that provide medium to high shear viscosity can improve the fullness and leveling of waterborne wood coatings, while rheological additives that increase high shear viscosity help leveling, Prevent splashing and improve roller and brush application performance.Therefore, the type and amount of rheological additives must be selected according to the requirements and system of the construction. Generally, the type of rheological additive is selected according to the different construction methods, and is often matched by three rheological additives of shear viscosity. In order to achieve the required construction results.
Polyurethane associative thickeners are currently the most widely used in waterborne wood coatings, but the choice of such thickeners in aqueous wood coating systems is closely related to the other ingredients in the formulation.For example, the thickening effect has a great relationship with the polymer particle size and hydrophobicity and the cosolvent in the waterborne wood coating. If the polymer particles in the waterborne wood coating are smaller, the more hydrophobic, and the distribution of the cosolvent in the polymer. The higher the coefficient, the higher the thickening efficiency, otherwise a large amount of such thickeners do not reach the desired viscosity.At the same time, it is recommended to dilute with water and add it under reasonable shearing force. Otherwise, it may also flocculate with the system to produce particles.

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