| In recent years, much research work in the field of pigment-dispersing aids has been focused on the synthesis of highly efficient polymeric dispersants (as are often called hyperdispersants), which may have a more favorable dispersability than the conventional surfactants. However, little work has been done in our country, so their use in the production of ink and paint is mainly depending on import product. In our work, effective hyperdispersants were synthesized through a three-step reaction. End-grouped polymers were first synthesized as the dispersing parts (solvated chains) and then coupled, through a coupling agent (TDI), with polyamine compounds as the adsorbing parts (anchoring groups). The hyperdispersants?adsorption property on several pigments was discussed in terms of different types and lengths of solvated chains, the number of the absorbing sites, temperature, dispersion medium, different pigments and so on. Much work had been done on their use in the production process of ink. Their wetting and dispersing ability was investigated. End-grouped polymer (PBuA or PMMA) containing aO2H or an H at one end was synthesized by chain-transfer radical polymerization of two monomers (BuA and MMA), initiated by AIBN. TGA or TEG was used both as chain-transfer agent and compound that contains another functional group. It was found that, when the ratio of chain-transfer agent to monomer amounts to 0.02 and initiator to monomer to 0.01, highly end-grouped polymers are obtained, which is the key to the synthesis of effective hyperdispersants in this thesis. By illustrating the relation of 1/P1 to [S]/[M], the chain-transfer constants of TGA and TEG were calculated as 0.67 and 0.64 respectively in the polymerization of BuA and TGA, 0.44, in the polymerization of MMA. In the coupling reaction, we found that the reaction rate of end-grouped polymer with polyamine compound is closely related to molecular weight of the polymer. In short, the reaction conditions were optimized. IR, H-NMR, GPC, and Titration methods were used to characterize the obtained product of each step. The adsorption property of the hyperdispersants on pigments was investigated after they had been purified. The adsorption isotherins were obtained through Gravimetric method and TGA (Thermo Gravimetric Analysis) as a comparison. Those dispersants with PBuA as solvated chains and polyamines as the anchoring groups have larger adsorption amount than other dispersants .The adsorption amount is also related to the types of pigments, temperature and the polarity and solubility parameter of solvent. Increasing the number of anchoring groups and decreasing the temperature and the solubility of dispersant in solvent will enhance the adsorption amount. The adsorption process is exothermic. The chemi-adsorption ratio of PB II ~hyperdispersant on titanium dioxide and red iron oxide, is 62% 92% respectively. Those researches may help illustrate the wetting and dispersing ability of the hyper dispersants and facilitate their right applications.When applied to the production of ink, those dispersants with PBuA as solvated chains and organic amines as the anchoring groups have a better wetting and dispersing ability than those with PMMA as solvated chains or 021-I as the anchoring groups. It can help reduce the milling time of pigments, improve the stability when setting-down, and alter the rheological property of dispersion, especially when... |
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