CLEAR AQUEOUS SOLUTIONS OF PHENOL-FORMALDEHYDE RESOL (VARIATIONS), METHOD FOR PREPARATION THEREOF (VARIATIONS), BINDING RESIN, HARDNESS-IMPARTING RESIN, AND TRANSPARENT RESIN Russian patent published in 2007 - IPC C08G8/10 C08G8/32 

FIELD: polymer materials.

SUBSTANCE: invention relates to colorless or slightly colored aqueous phenol-formaldehyde resols and to a method for preparing them. Provided is aqueous solution of high-molecular weight resol obtained by condensation of phenol compound with an aldehyde in presence of metal-chelating agent capable, in particular, of chelating iron, strong base, and hydroxyphenyl derivative of carboxylic acid, whereupon solution is acidified with an acid to pH 5-8. A method of preparing aqueous solution of high-molecular weight resol is also described, wherein (i) phenol compound, aldehyde, strong base, hydroxyphenyl derivative of carboxylic acid, and metal-chelating agent are heated at 60-75°C to form methylol solution; (ii) excess aldehyde is added to resulting solution and methylal solution of step (i) is subjected to condensation at pH 8-10 to form polymer solution; and (iii) resulting solution is acidified to pH 5-8. Binding resin for lignocellulose materials is further described as well as high-molecular weight resol aqueous solution, hardened resin prepared by heating-caused curing, and clear aqueous resin (variations).

EFFECT: enabled preparation of clear resol with small amount of free phenol, well soluble in water, possessing high molecular weight and low viscosity, stable on storage in solution, soluble at acid pH values, and capable of quickly hardening.

41 cl, 5 dwg, 8 ex