Formaldehyde → Melamine formaldehyde

참여 물질

반응 단계

5 Parts of partial sodium salt of polyvinylbenzenesulfonic acid (VERSA, TL500 manufactured by National Starch) was dissolved in 95 parts of hot water. The resulting solution was cooled and the pH thereof was adjusted to 4.0 by adding an aqueous solution of sodium hydroxide. 100 parts of diisopropylnaphthalene containing 4.5% of 3-(2-ethoxy-4-diethylaminophenyl)-3 (1-octyl-2-methylindole-3-yl)phthalide as the electron donating colorless dye dissolved therein was emulsified and dispersed in 100 parts of the above 5% aqueous solution of partial sodium salt of polyvinylbenzenesulfonic acid to obtain an emulsion having a particle size of 4.0μ in diameter. Separately, 6 parts of melamine, 11 parts of an aqueous solution of 37 wt % formaldehyde and 30 parts of water were heated at 60° C. with stirring. After 30 minutes, an aqueous solution of a transparent melamine-formaldehyde prepolymer was obtained. This aqueous solution was mixed with said emulsion. While stirring, the pH of the mixture was adjusted with 2M phosphoric acid solution to 6.0. The temperature of the solution was elevated to 65° C. and stirring was continued for 6 hours. The resulting capsule solution was cooled to room temperature, and the pH thereof was adjusted with an aqueous solution of sodium hydroxide to 9.0.

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