The process differs from the commonly accepted by the fact that the ionisation phase precedes the reaction of the isocyanate with the macro-diols and the hydrophilic monomers. The hydrophilic monomer is no longer used as containing a precursor ionic group, but as an ammonium salt to produce PUR prepolymers for anionic PUDs. This allows an early mono-phase system, which gives shorter reaction times and requires less or no solvent at all in the prepolymer phase. The presented examples “of the liquefied BisMPA” are completely compatible to all industrial processes coping with the requirements of the melt dispersion process, the acetone process and the solvent free process when the liquefying phase is the macrodiol itself.
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