Organic photo conductor (OPC) drums are prepared by the dip coating of the solution consists of photoconductive materials and binder resin onto aluminum pipes. The top of the pipe is closed during dip coating, but the bottom is open. Then, the solvent evaporates inside the pipe. Next, the inside pressure of the pipe is increased, and as a result bubbles break out at the surface of the coating solution.
Elapsed time till bubbling is related to the evaporativity of the solvent. Therefore, it is effective for prevention of bubbling to decrease the surface area of the solution and to suppress the evaporation of the solvent. The float is the best method for that purpose.
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