反应详情

温度

65 °C

A urea-formaldehyde-melamine prepolymer solution is prepared from 165 grams of 37% aqueous formaldehyde, 45 grams of water, 89 grams of urea and 1 gram of melamine, adjusted to pH 9.3 and heated for 1 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 1 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.

1. customresulting in an exothermic reaction
2. customWithout any preliminary phase separation
3. additionthe product is mixed with water