Appearance: low viscosity transparent liquid
Solubility: soluble in water-soluble paint, emulsion paint
Active ingredient(%): ≥45
Main components: Heterocyclic compounds
PH value: 6.0-8.0
Particle size: <40 microns
The anti-sagging performance or sag limit film thickness of non-Newtonian fluids is proportional to the yield value, that is, the larger the yield value, the better the anti-sagging performance, but the worse the leveling. Adding rheology modifiers makes the coating have certain thixotropic properties, which can not only increase the yield value of the coating, but also change the viscosity of the coating at high, medium, and low shear rates, that is, while improving the sag resistance, Give the system better flow and leveling effects, that is, make the viscosity of the coating gradually decrease with the increase of the shear rate. When the shear disappears, the viscosity will gradually recover. But pay attention to the effect of thixotropy on the speed of wet film viscosity recovery.
Fast recovery of viscosity is not conducive to leveling; slow recovery is conducive to leveling, but it is easy to cause sagging. When the yield value of the coating is less than 15mN/m², the leveling is better; when the yield value is >20mN/m², the leveling is very poor. For coatings with ideal rheological properties, before construction, the yield value should be >10mN/m², preferably >15mN/m³, and the yield value after construction should be immediately <5mN/m², preferably <2.5mN/m², and then the yield value Gradually restore to the original value.
Rheology modifiers commonly used in coatings include fumed silica, organic bentonite, hydrogenated sesame oil and polyamide wax. Fumed silica and organic bentonite have good thickening effect but poor rheological properties. After the shear force is removed, the viscosity recovers quickly, which is beneficial to prevent sagging, but has a small effect on leveling. Hydrogenated castor oil and polyamide wax The thixotropy and rheology of the film are relatively large. When the shearing force disappears, the viscosity of the wet film recovers slowly. A longer flow time is allowed for the coating film to level. The thickness sometimes still has a certain level of leveling, which is a very effective rheology additive for the manufacture of thick coating coatings. Because hydrogenated castor oil is very sensitive to temperature, its thixotropic effect is almost destroyed when the temperature is higher than 60°C, and cannot be restored after cooling. Therefore, great care should be taken during production, storage, transportation and use.
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