GB1448374A - Condensation resins based on phenol-aldehyde resins - Google Patents

Abstract

1448374 Novolak resins HOECHST AG 6 Nov 1973 [7 Nov 1972] 51400/73 Headings C3R and C3B [Also in Division C2] A novolak resin is prepared by reacting simultaneously a phenol, an aldehyde and an olefinically unsaturated aromatic component selected from olefinically unsaturated aromatic hydrocarbons and alpha-chlorostyrene in the presence of an acid catalyst, water being continually removed from the reaction mixture. The phenol-aldehyde molar ratio is preferably from 1 : 0À5 to 1 : 1 and the phenol/aromatic component molar ratio is preferably from 1 : 0À1 to 1 : (3-2n) where n is the number of mols. of aldehyde per mol. of phenol. Suitable phenols are phenol, cresols, xylenols having 2 hydrogen atoms in the o- and/or p-positions to the OH group, butylphenols, naphthols, resorcinol, diphenylolmethane and diphenylolpropane. Suitable aldehydes are formaldehyde, paraformaldehyde, trioxan, acetaldehyde, propionaldehyde, .butyraldehyde, isobutyraldehyde and benzaldehyde. Suitable aromatic compounds are styrene, alpha- or beta-methylstyrene, vinyltoluene, divinylbenzene, indene and alpha-chlorostyrene. The reaction may be performed in an organic solvent and the water formed during the reaction is preferably continually distilled off and the solvent recycled into the reaction mixture. Suitable acid catalysts are strong protonic acids such as H 2 SO 4 , HCl, H 3 PO 4 , an aromatic sulphonic acid or a hydroxy sulphonic acid, and Lewis acids such as AlCl 3 , ZnCl 2 , SnCl 4 , and the etherates and acetates of boron trifluoride. The novolak produced may be modified by reaction with epichlorohydrin in the presence of an alkali to yield an epoxy resin, or by reaction with an alkylene oxide to yield a diol. In the examples, novolaks are prepared (1) by first heating phenol with H 2 SO 4 and then reacting with vinyltoluene and either trioxan or aqueous HCHO; (2) by first heating phenol with aqueous phenolsulphonic acid, followed by reaction with aqueous HCHO, followed by dehydration, and then reacting the modified phenol with trioxan and styrene; (3) by first heating phenol with H 2 SO 4 and then reacting with styrene and trioxan. Toluene or xylene are used as solvents. Resin (3) is further reacted with epichlorohydrin in the presence of NaOH to produce an epoxy resin or with propylene oxide in the presence of NaOH.