Fluidized bed coating process and apparatus

Claim 1

AN APPARATUS FOR COATING ARTICLES COMPRISING A CONTAINER HAVING AN OPEN TOP THROUGH WHCIH ARTICLES TO BE COATED MAY BE INSERTED AND IMMERSED INTO A FLUIDIZED BED OF FINELY DIVIDED PARTICLES OF COATING MATERIAL CONFINED THEREIN, A GAS PERVIOUS CERAMIC PLATE MOUNTED HORIZONTALLY IN THE CONTAINER TO PARTITION THE CONTAINER INTO AN UPPER CHAMBER FOR CONTAINING THE BED OF COATING MATERIAL AND A LOWER CHAMBER, A JACKET SURROUNDING THE SIDES AND BOTTOM OF SAID CONTAINER FOR CONTAINING A LIQUID HEAT TRANSFER MEDIUM HAVING A BOILING POINT BELOW THE MELTING POINT OF THE COATING MATERIAL, A HELICAL GAS SUPPLY TUBE POSITIONED AROUND THE CONTAINER WITHIN THE JACKET AND CONNECTED TO SAID LOWER CHAMBER, CONNECTIONS FOR SUPPLYING GAS UNDER PRESSURE THROUGH THE TUBE AND SAID LOWER CHAMBER AND SAID PLATE TO FLUIDIZE THE BED, AND A HEATING UNIT MOUNTED ADJACENT TO THE JACKET FOR TRANSMITTING HEAT THROUGH THE LIQUID TRANSFER MEDIUM TO THE FLUIDIZED BED AND TO THE GAS.

Claim 2

AN APPARATUS FOR COATING ARTICLES COMPRISING A CONTAINER HAVING AN OPEN TOP THROUGH WHCIH ARTICLES TO BE COATED MAY BE INSERTED AND IMMERSED INTO A FLUIDIZED BED OF FINELY DIVIDED PARTICLES OF COATING MATERIAL CONFINED THEREIN, A GAS PERVIOUS CERAMIC PLATE MOUNTED HORIZONTALLY IN THE CONTAINER TO PARTITION THE CONTAINER INTO AN UPPER CHAMBER FOR CONTAINING THE BED OF COATING MATERIAL AND A LOWER CHAMBER, A JACKET SURROUNDING THE SIDES AND BOTTOM OF SAID CONTAINER FOR CONTAINING A LIQUID HEAT TRANSFER MEDIUM HAVING A BOILING POINT BELOW THE MELTING POINT OF THE COATING MATERIAL, A HELICAL GAS SUPPLY TUBE POSITIONED AROUND THE CONTAINER WITHIN THE JACKET AND CONNECTED TO SAID LOWER CHAMBER, CONNECTIONS FOR SUPPLYING GAS UNDER PRESSURE THROUGH THE TUBE AND SAID LOWER CHAMBER AND SAID PLATE TO FLUIDIZE THE BED, AND A HEATING UNIT MOUNTED ADJACENT TO THE JACKET FOR TRANSMITTING HEAT THROUGH THE LIQUID TRANSFER MEDIUM TO THE FLUIDIZED BED AND TO THE GAS.

Claim 3

A METHOD OF COATING ARTICLES COMPRISING THE STEPS OF INTRODUCING A GAS INTO A BED OF FINELY DIVIDED FREE-FLOWING POWDERED COATING MATERIAL TO FLUIDIZE THE BED, SUPPLYING EXTERNAL HEAT ABOVE AMBIENT TEMPERATURE TO THE FLUIDIZED BED THEREBY TO HEAT SAID BED TO A PREDETERMINED TEMPERATURE ABOVE AMBIENT TEMPERATURE AND APPROACHING BUT NOT EXCEEDING THE SINTERING POINT OF THE COATING MATERIAL, HEATING AN ARTICLE TO BE COATED TO A TEMPERATURE ABOVE THE SINTERING POINT OF THE COATING MATERIAL, AND IMMERSING THE HEATED ARTICLE IN THE HEATED FLUIDIZED BED.

Claim 4

A METHOD OF COATING ARTICLES COMPRISING THE STEPS OF INTRODUCING A GAS INTO A BED OF FINELY DIVIDED FREE-FLOWING POWDERED COATING MATERIAL TO FLUIDIZE THE BED, SUPPLYING EXTERNAL HEAT ABOVE AMBIENT TEMPERATURE TO THE FLUIDIZED BED THEREBY TO HEAT SAID BED TO A PREDETERMINED TEMPERATURE ABOVE AMBIENT TEMPERATURE AND APPROACHING BUT NOT EXCEEDING THE SINTERING POINT OF THE COATING MATERIAL, HEATING AN ARTICLE TO BE COATED TO A TEMPERATURE ABOVE THE SINTERING POINT OF THE COATING MATERIAL, AND IMMERSING THE HEATED ARTICLE IN THE HEATED FLUIDIZED BED.