GB783537A - Phenol-aldehyde resinification - Google Patents

Abstract

<PICT:0783537/IV (a)/1> In a continuous process for making phenolaldehyde resins, for use in making moulding compositions, laminations, adhesives and surface coating materials, a phenol and an aldehyde are continuously introduced into a large volume of an aqueous solution of the same reactants, the solution being maintained (a) at an elevated temperature to effect continuous condensation of the reactants, and (b) in a quiescent state to permit continuous settling of the resin as it is formed into a lower liquid layer which is continuously withdrawn to prevent further condensation of the resin. The process may be effected in one, but preferably more than one, reactor and at normal or super atmospheric pressure. In one embodiment (Fig. 1), a mixture of formalin (5 mol.) phenol (6 mol.) and sulphuric acid in amount of 1/2 per cent by weight of the phenol is continuously introduced through line 1 and pipe 3 into the lower part of a body of water contained in the first of three reactors (5, 19, 32), each succeeding one of which is disposed at a lower elevation than each preceding one, each one being surrounded by a heating (8, 21) and/or cooling (34) jacket, and each being provided with vapour lines (9, 22, 41) for condensation at 11 of gases and vapours liberated during reaction, the condensate being returned to reactor 19 or, if necessary, to reactor 5. The liquid resin formed in the quiescent body of reaction liquid settles to the bottom of reactor 5 to form a layer 14 which is continuously discharged through lines 15, 48 to a steam-jacketed accumulator tank 49, while the upper aqueous layer containing unreacted phenol and aldehyde is passed into succeeding reactors 19, 32, for further formation and settling of resin, and then to waste via pipe 36, the resin from these reactors also being discharged into tank 49. Any water which has separated in tank 49 is bled-off through lines 52, vapour and gases are released through line 50 to condenser 11, and the liquid resin is passed via line 53 to a dehydrator. In a further embodiment (Fig. 2, not shown), the reactants are continuously fed into the first of three jacketed vessels disposed vertically below one another. The first vessel is steam heated and the resin which forms and settles in layer on the bottom of the vessel is passed separately but simultaneously with the aqueous layer into the second vessel, the upper part of which is cooled and the lower part heated thereby minimizing further condensation of the already formed resin and causing further separation and settling of resin. The resin is then discharged into the third vessel, which is a steam-heated accumulator tank, and treated in a manner similar to that set forth in the first embodiment. Examples are given. Phenol or homologues thereof and tar acids (mixture of phenol, cresols and xylenols), and formaldehyde, paraldehyde, acetaldehyde and furfural, and as catalysts sulphuric and oxalic acids and ammonium hydroxide, are specified. Pigments and drying oils may be added to the reactants in the production of certain pigmented moulding resins and varnishes. Specification 680,245 is referred to.