METHOD OF PREPARING LIQUID RESOL PHENOLFORMALDEHYDE RESIN Russian patent published in 1997 - IPC

FIELD: chemical technology. SUBSTANCE: liquid resol phenolformaldehyde resins were obtained by two-stage polycondensation of phenol with formaldehyde at their molar ratio = 1:(1.2-1.5), respectively. The first stage of process is carried out at one-time loading all formaldehyde using alkaline metal hydroxide as catalyst at reaction mixture boiling point up to formaldehyde conversion to methylene links at the range 0.20-0.42 mole/1 mole parent phenol. At the second stage the remained formaldehyde is bound to methylol groups in the presence of calcium hydroxide at 55-80 C up to the remained formaldehyde mass part 0.2-1.0%. Then the obtained product is neutralized with benzenesulfonic acid and resin is dried under vacuum. Resin-base foam plastic at required apparent density is obtained at the range 10-75 kg/$$$. EFFECT: decreased equipment corrosion, simplified method and operation. 2 tbl