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| Why should a coalescing aid have low water solubility? |
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| Water miscible coalescing aids distribute themselves between the polymer and water phases. The more hydrophilic (water loving) the coalescing aid, the more its tendency to partition to the water phase of the latex system. This partitioning preference could reduce its coalescing efficiency under high humidity /low temperature conditions. Some of the coalescing aid will evaporate out with the water and lessen its ability to coalesce the suspended particles into a continuous film. A good coalescing aid will have water insolubility to minimize coalescing aid loss during water evaporation. If water insoluble, there is also less tendency for the coalescing aid to migrate into a porous substrate. A good coalescing aid will migrate into the latex polymer and remain after the water has evaporated to coalesce the latex resin. |
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