Process for making powder coatings
AssigneeCelanese Polymer Specialties Company
InventorJohn Edward Masters
Life of this patent
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Abstract
Powder coating compositions are prepared by first forming a dispersion in water of a complex polyhydroxy polyether resin using as the dispersant an inorganic or organic base salt of a polymeric carboxylic acid having an acid value before salting of at least 50, acidifying the dispersion and then isolating and drying the precipitated fine particle size resin. Such resins in this finely divided form find particular utility as powder coatings for metallic articles.
Claims17
A process for preparing finely divided particles of a complex polyhydroxy polyether resin having a melting point of at least 80.degree. C. which comprises
- a. mixing at a temperature of at least 60.degree. C. said resin with water having dissolved or colloidally dispersed therein an inorganic or organic base salt of a polymeric polycarboxylic acid, said acid having an unsalted acid value of at least 50, wherein said polymeric salt is present at about 1 to 25 weight percent based on the weight of said resin;
- b. agitating the mixture to form a dispersion having a particle size of about 1 to about 50 microns;
- c. reducing the solids content of the dispersion with water;
- d. cooling the dispersion below the melting point of the resin;
- e. acidifying the dispersion to a pH of about 1 to about 7;
- and
- f. recovering the dispersed particles.
Dependencies are inferred from the claim text.