Fluidized bed coating process employing an epoxy resin, and process for preparing said resin

Claim 1

IN THE PROCESS FOR COATING AN ARTICLE WITH AN EPOXY RESIN WHICH COMPRISES (1) PREPARING A DRY, FLUIDIZABLE POWDERED EPOXY RESIN COMPOSITION, (2) FLUIDIZING SAID COMPOSITION BY PASSING A DISTRIBUTED ASCENDING CURRENT OF INERT GAS THERETHROUGH TO FORM A DENSE-PHASE FLUIDIZED BED, (3) HEATING THE ARTICLE TO BE COATED TO A TEMPERATURE WHICH LIES BETWEEN THE SINTERING POINT AND THE DECOMPOSITION POINT OF THE COATING COMPOSITION AND BELOW THE DETERIORATION POINT OF THE ARTICLE, (4) IMMERSING THE HEATED ARTICLE IN SAID DENSE PHASE, (5) REMOVING THE ARTICLE CONTAINING A LAYER OF COATING MATERIAL ADHERING TO ITS SURFACE AND (6) MAINTANING SAID COATED ARTICLE AT AN ELEVATED TEMPERATURE FOR A SUFFICIENT TIME TO CURE SAID COATING, THE IMPROVEMENT WHICH COMPRISES EMPLOYING AS SAID POWDERED COMPOSITION A FLUIDIZABLE PULVERULENT MASS OF PARTICLES OF HOMOGENOUS COMPOSITION PREPARED BY (1) PREHEATING A SOLID POLYEPOXIDE TO THE CONSISTENCY OF TAFFY, (2) ADDING THERETO AT LEAST A THIXOTROPIC AGENT AND AN EXPOXIDE CURING AGENT SELECTED FROM THE GROUP CONSISTING OF DICYANDIAMIDE AND PHENOL BLOCKED POLYISOCYANATE RESIN WHICH DOES NOT SUBSTANTIALLY INTERACT WITH SAID EPOXIDE AT TEMPERATURES BELOW ABOUT 250*F., (3) MILLING THE RESULTING MIXTURE IN A RUBBER MILL AT AND ELEVATED TEMPERATURE NOT IN EXCESS OF ABOUT 250* F. FOR A SUFFICIENT TIME TO PRODUCE A UNIFORM BLEND, AND (4) COOLING AND PULVERIZING SAID BLEND.