Based On Hyperbranched Polymer Pigment Dispersant

Hyperbranched polymer has received much attention in recent years. Many newlydeveloped hyperbranched polymers are based on various kinds of chemical structures,including polyphenylene, polyether, polyester, etc. Their tri-dimensional structure,ultra-high functionality, special solution behavior, and all the related chemical andmechanical properties have been widely evaluated.Hyperbranched polymers have also been tried to be applied into industrial fields, suchas modification resin for adhesives, UV curable resins, and for polyurethaneelastomers, etc.But it has seldom been reported that hyperbranched polymers have been developedas a dispersing agent to pigments.High Molecular Weight Dispersants, developed since 1970s', are necessary additiveswhich have been widely used in automotive and industrial coatings and high-endprinting inks to disperse and stabilize carbon black and all those organic pigments,achieving an excellent color effect.This work, is aimed to the synthesis of a hyperbranched polymer, and to theevaluation on the performance of this polymer acting as a dispersing agents inindustrial coatings.The hyperbanched polyester is synthesized from 2,2-dimethylol-propionic acid(DMPA),and trimethylol propane, according to a known process. Then the hydroxyl groups arepartially blocked with a fatty acid, and the rest are transferred to isocyanate groups byreacting with a diisocyanate, such as isophorone diisocyanate(IPDI). Finally, thepigment abchoring group, an organic amine is introduced, and a pigment dispersingagent is obtained.GPC, FT-IR, ~1H-NMR, have been used to measure and determine the structure.The dispersing agent developed based on hyperbranched polyester is then appliedinto commercial automotive industrial coating. Comparing with the commercialpolyurethane type polymeric dispersant, the newly developed dispersants withhyper-branched structure shows capability to stabilize the organic and inorganicpigments, and gives special rheological behavior. This work could provide a new method to make use of hyperbranched polymer as a functional additive, and could become one of the basic references for further more application developments of hyperbranched polymers.