Process for preparing high ortho novolac resins

Claim 1

In a process for the production of phenol-aldehyde novolac resins of the class which is characterized by having a preponderance of ortho/ortho methylene bridges and which is prepared by an acid reaction mixture containing a material selected from the group consisting of phenol and meta-alkylphenols in molar excess with a source of formaldehyde, conducting said reacting in the presence of a catalyst system comprising in combination: (A) a divalent electropositive metal compound selected from the group consisting of oxides, hydroxides, organic acid salts, sulfonic acid salts, halogen acid salts and fluoroborate acid salts of said metals or mixtures thereof, and (B) an acid material selected from the group consisting of halogen, fluoroboric and sulfonic acids and divalent metal salts of said acids or mixtures thereof, said catalyst system being at least partially soluble in said reaction mixture and being present amounts such that the pH of said reaction mixture is maintained at about 4 to 7, wherein the improvement comprises conducting said reacting under anhydrous conditions wherein said anhydrous conditions are provided by azeotropic distillation and removal of a water phase during said reacting, said reacting being carried out at a temperature of 115° to 145° C. with a molar ratio of phenol to formaldehyde of about 1.2:1 to 2.0:1 providing said novolac resin with about 80 to 95% ortho-ortho methylene bridges said novolac having a weight average molecular weight greater than 400.