Room temperature coalescable aqueous fluoropolymer dispersions and method for their manufacture

A coating composition comprising an aqueous dispersion of particles, which particles comprise a semi-crystalline first copolymer enveloped by an amorphous second copolymer wherein:

• a) the semi-crystalline first copolymer has at least two comonomer units of the formula:
• CX.sub.2 CYA
• wherein
• X is independently selected from H, Cl, or F;
• Y is H, Cl, F, O(CZ.sub.2).sub.n CZ.sub.3, (CZ.sub.2).sub.n CZ.sub.3, (OCZ.sub.2 CZ.sub.2).sub.n CZ.sub.3, or (O(CZ.sub.2).sub.n).sub.n CZ.sub.3 wherein n is from about 1 to about 12;
• Z is independently selected from H or F;
• A is X, Cl, or F;
• the first copolymer contains at least about 4 weight percent of each of the comonomer units;
• and
• at least one of the first comonomer units contains a fluorine atom;
• and
• b) the amorphous second copolymer is the reaction product of a cure site provider and at least two comonomer units of the formula:
• CX.sub.2 CYB
• wherein
• X and Y are as defined above;
• B is H, Cl, F or --OCOR;
• wherein R is a linear or branched aliphatic hydrocarbon of from 1 to 20 carbons;
• and
• at least one of said comonomer units contains a fluorine atom.