Silicone oil has high and low temperature resistance, excellent electrical insulation, good aging resistance, low surface tension, tasteless, physiological inertness, low viscosity-temperature coefficient, higher compressibility, low play, better lubricity, etc.
The HLB and dissolution parameters of the dispersion medium of the coating additive cannot cause significant changes in the charging of the pigment, but it is related to the type of pigment, especially the charging property of the organic pigment, which clearly does not change with the dispersion medium.
The charging tendency of these pigments is related to the displacement groups in the pigment structure. A substance having an electron-accepting group such as a nitro group and a halogen group is negatively charged, and a substance having an electron-donating group such as an amino group is positively charged.
Kitawaramoto proposed that the electrolyte is slightly ionized in a non-polar medium, wax additive number and the ions produced in the following conditions can play a part of stabilizing effect.
a. Substances with large ionic radius, such as alkyl quaternary ammonium salts.
b. In the surfactant solution, the dissociated ions can be stably dissolved in the micelles.
In addition, if the dispersion system contains a small amount of water, HT or OH- will be produced due to the ionization of water. They will preferentially adsorb to the particle surface, which causes the particles to have different charges at the interface. According to whether the dispersion system contains surfactants, the following two situations will occur.
The dispersion system does not contain ionic surfactants and only contains a small amount of water. Because the pigment (P) and the solvent (S) are different in acidity and alkalinity, either H+ or OH- is obtained, the following mode will be formed; the dispersion system contains ionic surfactants, and the ions generated by ionization will be in accordance with the particle The affinity is adsorbed on the surface of the particles.
Hydrophilic particles such as titanium dioxide and barium sulfate, when a cationic surfactant is used, have a strong affinity for Na+, etc., and are positively charged. When it comes to surfactants, it is not so simple, and the effect of water should also be considered.
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