Formaldehyde → Urea, polymer with formaldehyde and 1,3,5-triazine-2,4,6-triamine

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A urea-formaldehyde-melamine prepolymer solution is prepared from one-hundred sixty-five grams of 37% aqueous formaldehyde, forty-five grams of water, eighty-nine grams of urea and one gram of melamine, adjusted to pH 9.3 and heated for one hour at 65° C. One-hundred seventy grams of this prepolymer solution are emulsified in a solution of six grams of Tetronic 1502 dissolved in one-hundred grams of xylene, and 0.06 milliequivalents of sulfur dioxide (about 4 normal in xylene solution) is added, resulting in an exothermic reaction. After stirring for one hour, the solvent dispersion has little or no precipitate. Without any preliminary phase separation, the product is mixed with water to give about 16% total solids, and this "aqueous redispersion" is steam distilled under high-shear agitation to yield a product free of of residual xylene, closely resembling that described in Example 1. A paper coating prepared as described in Example 1 has a scatter coefficient of about 4,000 cm2 /gram.

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