反应详情

A urea-formaldehyde prepolymer solution is prepared by heating an aqueous solution of two-hundred-twenty grams of 37% formaldehyde and 82 grams of urea, adjusted to pH 8 with triethanolamine, at 70° C for one hour. Fifty grams of this prepolymer solution are mixed with thirty grams of a 50% by weight dispersion of titanium dioxide in distilled water, and adjusted to pH 6 with dilute sulfuric acid. The aqueous dispersion is emulsified in a solution of six grams of Pluronic L122, three grams of sorbitan monooleate (commerically available as Span 80 from ICI America) and 1.5 grams of a poly(oxyethylene)-poly(oxypropylene) block copolymer with 30% poly(oxyethylene) and a molecular weight of about 2500 (commercially available as Pluronic L 63) in one-hundred grams of xylene to yield a water-in-oil emulsion. This is treated with four milliliters of a 50% by weight solution of monobutyl acid phosphate in toluene and stirred for two hours.