Defoaming agent polydimethylsiloxane is the main component of solvent coating defoaming agent, some of which contain white carbon black; Others need to be used in conjunction with leveling agents, which need to be mixed into the system under high shear forces and are suitable for eliminating bulbous bubbles. Due to the elongated carbon chain of the side groups, the phenyl and alkyl antifoaming agents have good compatibility with the organic system, and have the function of eliminating microbubbles, which complements the deficiency of the foregoing antifoaming agents. The adding amount of defoaming agent started with 50×10, and increased or decreased appropriately according to the defoaming effect.
UV type coating can use solvent coating with defoaming agent, can also use 5% fluoroalkyl modified silicone methyl isobutyl ketone solution.
Defoaming agent and defoaming system is not compatible to better defoaming; But in order to make the defoaming agent well dispersed in the system, water-based coatings with defoaming agent generally use silicone oil water emulsion, small HLB value of organosilicon polyether copolymer and organic modified organosilicon. The addition amount was 0.05% ~ 1%. Silicone oil water emulsion containing treated silica has good defoaming effect and stability. The silicone polyether copolymers used in the defoaming agent are all hydrophobic, with HLB value of 1.31 ~ 1.90, viscosity of 500~750mm2/s, turbidity point < At 0℃, the surface tension of 0.1% aqueous solution is about 26mN/m. Organic modified organosilicone is dipropylene glycol monomethyl ether solution with the mass fraction of active component of 20%. Its viscosity is only 45 ~ 65mm2/s. It does not contain hydrophobic particles and is easy to disperse in water system. Due to the use of organic base modification, it has good compatibility with organic resin, that is, it does not affect the luster or have surface defects.