Methods and apparatus for spraying solvent-borne compositions with reduced solvent emission using compressed fluids and separating solvent
AssigneeUnion Carbide Chemicals & Plastics Technology Corporation
InventorKenneth A. Nielsen
Life of this patent
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Abstract
A method and apparatus are provided for spraying a solvent-borne composition with reduced emission of organic solvents by exchanging a portion of the organic solvent diluent with a compressed fluid such as carbon dioxide, by adding the compressed fluid under pressure to maintain low viscosity and to facilitate solvent separation, separating a portion of the organic solvent, and spraying the resulting composition with compressed fluid.
Claims19
A method for spraying a solvent-borne composition with reduced emission of organic solvent while maintaining low viscosity, said solvent-borne composition comprising:
- (i) a nonvolatile materials fraction capable of being sprayed as a liquid solution or dispersion;
- and
- (ii) a solvent fraction containing at least one organic solvent in which said nonvolatile materials fraction is at least partially soluble or dispersible and at least in an amount which is sufficient to render the viscosity of said solvent-borne composition having a viscosity of less than about 200 centipoise,
- (a) forming a precursor liquid spray mixture in a closed system, said precursor liquid spray mixture comprising said solvent-borne composition and, in addition,
- (iii) at least one compressed fluid under sufficient pressure and at least in an amount which when added to said solvent-borne composition is sufficient to maintain said precursor liquid spray mixture transportable after at least a portion of said solvent fraction is separated in step (b), said compressed fluid being a gas at standard conditions of 0.degree. Celsius temperature and one atmosphere pressure (STP);
- (b) separating at least a portion of solvent fraction (ii) from said precursor liquid spray mixture to form a liquid spray mixture having less organic solvent than said precursor liquid spray mixture, and then
- (c) passing the thusly formed liquid spray mixture under pressure through an orifice to form a spray.
A method of spraying a solvent-borne additives composition to a polymeric substrate prior to extrusion, filming, molding, or processing of the polymeric substrate with reduced emission of organic solvent while maintaining low viscosity, said solvent-borne additives composition comprising:
- (i) a dispersed solid additives fraction containing at least one dispersible solid additive capable of being sprayed as a dispersion;
- (ii) a polymer fraction containing at least one polymeric compound;
- and
- (iii) a solvent fraction containing at least one organic solvent in which said at least one polymeric compound is at least partially soluble and at least in an amount which is sufficient to render the viscosity of said solvent-borne additives composition to less than about 200 centipoise, which method comprises:
- (a) forming a precursor liquid spray mixture in a closed system, said precursor liquid spray mixture comprising said solvent-borne additives composition and, in addition,
- (iv) at least one compressed fluid under sufficient pressure and at least in an amount which when added to said solvent-borne additives composition is sufficient to maintain said precursor liquid spray mixture transportable after at least a portion of said solvent fraction is separated in step (b), said compressed fluid being a gas at standard conditions of 0.degree. Celsius temperature and one atmosphere pressure (STP);
- (b) separating at least a portion of solvent fraction (iii) from said precursor liquid spray mixture to form a liquid spray mixture having less organic solvent than said precursor liquid spray mixture, and then
- (c) passing the thusly formed liquid spray mixture under pressure through an orifice to form a spray and directing said spray at a polymeric substrate to deposit said additives thereon.
Dependencies are inferred from the claim text.