Patent GB-630162-A (GB)
Title: Alkali and acid resistant polyamine-modified phenol-formaldehyde resins
IPC: C08G8/00
Filed: 1947-03-11
Abstract: Modified phenol-formaldehyde resins are made by reacting a base-catalyzed phenol-formaldehyde condensate with an open chain alkylene polyamine, and coating materials are made by cold-blending a dehydrated base-catalyzed phenol-formaldehyde condensate with a methylol substituted open chain alkylene polyamine.  The molal quantity of polyamine lies between 1/f and 1, desirably being 1/n, per phenolic hydroxyl group.  f is the functionality of the amine, viz. the total number of replaceable hydrogen atoms in the amino or imino groups and is more than 2; n is the total number of amino and imino groups and is an integer higher than 1.  Free formaldehyde present during the reaction should not exceed 1 mol. per mol. of the polyamine, so as to prevent gelation, and the amount of formaldehyde in excess of equimolecular proportions, reacted with the phenol before the addition of the polyamine, should not be more than 2 mols. per mol. of the polyamine.  If a short reaction time has been used, the resins are soluble in water and the lower monohydric alcohols p or their esters, such as acetates or propionates, to provide impregnants or binders for laminated products or, with a longer reaction time, are soluble in dioxane and glycol or polyglycol monoethers to provide thermo-setting adhesives or baking coatings, particularly for metal, or, with still further reaction time (i.e. short of converting the phenol-formaldehyde condensate before adding the polyamine into a B-type resin), to provide solid, brittle resins for moulding.  Phenols include phenol, meta cresol, 3.5 xylenol, phenols including a proportion of o- and p-cresols, and xylenols, polyhydroxy-polyarylmethanes, diphenylolethanes, dicresyl and dihydroxyxylenylmethane derivatives.  Polyamines include ethylene diamine, 1.3 and 1.2-diamino propane, diethylene triamine, triethylene tetramine, tetraethylene pentamine and 1.6-hexamethylenediamine and polyamines with imino groups only, such as 3.31-di(ethylamino) dipropylamine.  The final conversion temperature is preferably at least 160 DEG  C. or between 175 DEG  C. and 200 DEG  C.  Basic catalysts include ammonium hydroxide, hexamethylene tetramine, quaternary ammonium bases, amines, sodium and potassium hydroxides, zinc, calcium and magnesium oxides.  In an example, 10 mols. of phenol were reacted with 10 mols. of aqueous formaldehyde in the presence of ammonia and the syrup dehydrated at 50 DEG  C. under 2 inches pressure.  3.3 mols. of diethylene triamine in ethylene glycol monoethyl ether was added, the mixture being heated for 15 minutes under atmospheric reflux to 100 DEG  C., then cooled, and 6.7 mols. of paraformaldehyde in ethylene glycol monoethyl ether added and reacted at 80 DEG  to 85 DEG  C. under 3 inches pressure.  Further solvent was added to give a solution which, baked on metal surfaces, gave an alkali and acid resistant film. Other examples showing variations in the reactants and conversion temperatures and the alkali and acid resistance of films coated on metal surfaces include one (example 18) in which a solution of a phenol formaldehyde condensate was cold-blended with a solution of a methylol substituted diethylene triamine.  In a further example (example 2) a phenolformaldehyde resin made with hexamethylene tetramine as catalyst, was reacted with diethylene triamine, paraformaldehyde being added at a later stage and the resin dehydrated to obtain a brittle resin which was ground and mixed with paraform, lime, stearic acid, carbon black and cotton flock to give a moulding powder.