The ratio of pigment to substrate in electrophoretic coating refers to the ratio of pigment to substrate (resin) in electrophoretic coating, plating solution or paint film. The determination of pigment alkali ratio includes solvent method and ash content method. In addition to carbon black, the pigments used in electrophoretic coatings are generally non-combustible inorganic pigments. Therefore, the ash content is usually used to calculate the pigment content. The method is simple and convenient.
(1) Testing instruments and materials
① Crucible and muffler
②Constant temperature oven
(2) Measurement method
① Weigh a quantitative (about 10g) paint sample or tank liquid sample into a weighing crucible;
② Bake at 110±5°C for 1 hour, then bake at 200-250°C for 1 hour, bake at 400-450°C for 0.5 hour, and calcine at 800°C for 0.5 hour;
③Weigh the crucible again after cooling;
④Calculation:
Ash = (CA) × 100/[(BA) × (D/100)]
Color base ratio (P / B) = (c - a) / K (KD (B)——(c - a))
Place:
A crucible weight (g)
B crucible plus sample weight (g)
C The weight of the sample added to the crucible after calcination (g)
D paint sample solids (%)
K is the correction coefficient of carbon black, K=1.15 in black paint
