Patent ID: 6221435
Filing Date: 2001-04-24
Classification: B05D

Abstract:
A process for spraying a liquid coating composition comprising polymeric compounds to form a coating on a substrate, which comprises the steps of:(1) forming a liquid mixture in a closed pressurized system, said liquid mixture containing a coating composition and a subcritical compressed fluid wherein:(a) the coating composition contains at least one polymeric compound having a number average molecular weight (M.sub.n) of less than about 5,000; and(b) the subcritical compressed fluid is miscible with and forms a liquid mixture with said coating composition and is present in the liquid mixture in an amount which renders the viscosity of said liquid mixture suitable for spraying and being capable of forming a choked flow when sprayed, and wherein said subcritical compressed fluid is a gas at standard conditions of 0.degree. C. temperature and one atmosphere pressure (STP);(2) spraying said liquid mixture by passing the liquid mixture through an orifice at a temperature and pressure that produces choked flow of the liquid mixture being sprayed which forms the spray; and(3) applying said spray containing said coating composition to said substrate to form a liquid coating thereon, wherein the pressure of the environment outside said orifice into which said liquid mixture is sprayed onto said substrate is below the choke pressure of said choke flow of said liquid mixture.