Low viscosity liq. epoxy! resins - made by multistage reaction of epichlorohydrin with 2,2-bis-(p-hydroxyphenyl)-propane or phenolic resin

摘要

Low viscosity liq. epoxy resins which can be cured at room temp. in anhydrous or aq. medium are made by first reacting 0.1-1.0 mol. of 2,2-bis-(p-hydroxyphenyl)-propane and/or 0.1-1 mol. phenolic resin(s) with 1-4 mols epichlorhydrin and 0.3-4 mols. NaOH to form a precondensate, esp. with a viscosity of 5-50 cP at 25 degrees C. The NaCl formed is opt. removed with water and the water decanted. Condensn. of the resin is then effected under reduced pressure with distn. of excess epichlorhydrin until the prod. has an epoxy equiv. of 200-250 and a viscosity of 100-2000 cP at 25 degrees C. The NaCl formed is opt. removed with water, then 0.1-2 mols. 25 plus-or-minus 5% aq. NaOH soln. is added and the resin is further condensed at elevated temps. under reduced pressure, after which the volatile components are blown out with steam and >=1 inert gases and the condesn. is continued to the required viscosity. Process gives low viscosity liq. epoxy resins which can be used at room temp. with known epoxy curing agents either in anhydrous or aq. medium (e.g. as emulsions or dispersions).