2020 Volume 71 Issue 5 Pages 371-375
Transition from solvent-based paints to water-based paints in the painting industry has progressed to reduce the use of volatile organic compounds, which are harmful to humans and the environment. However, water-based paints have a problem with paint workability because of sagging. Cellulose nanofiber (CNF), which has attracted attention as a novel naturally available material, exhibits high mechanical strength, thickening effects, and a low coefficient of thermal expansion. To resolve difficulties related to water-based paints, we examined paint and coating films characteristics after adding CNF. Results demonstrated that adding 0.2 mass% CNF can prevent sagging. Paint separation attributable to pigment sedimentation was prevented for 10 days. By adding 0.5 mass% CNF, the tensile strength of a coating film became more than double that of a non-CNF coating film. Testing using ballotini method indicated that CNF addition decreased the coating film surface dryness. Measurements using AC impedance indicated decreased coating film water resistance.
