Abstract An aqueous latex coating composition adapted to deposit films which dry to form a layer of high opacity is provided by absorbing within the polymer particles of the aqueous latex a small amount of an aliphatic organic solvent, such as mineral spirits, which is essentially immiscible in the aqueous phase of the latex and which causes the polymer to fracture, and by introducing into the aqueous phase an at least partially water miscible organic solvent, such as propylene glycol, having a lower evaporation rate than the aliphatic solvent. When the aliphatic solvent evaporates, a film is formed which is extensively fractured, the secondary solvent serving to maintain these fractures and thereby increase the opacification which is obtained.
An aqueous latex coating as recited in claim 1 in which said aliphatic organic solvent is mineral spirits.
Claim 2
Dependent Claim
49 words
An aqueous latex coating as recited in claim 1 in which said polymer particles are particles of emulsion polymer having a glass transition temperature below 25*C. modified by having monomer which produces a polymer having a glass transition temperature above 30*C. post polymerized in their presence by emulsion polymerization.
Claim 3
Dependent Claim
42 words
An aqueous latex coating as recited in claim 3 in which said polymer particles are particles of ethylene-vinyl acetate emulsion copolymer having a monomer selected from the group of styrene, vinyl toluene and methyl methacrylate polymerized in an emulsion of said copolymer.
Claim 4
Dependent Claim
31 words
An aqueous latex as recited in claim 1 in which mixtures of emulsion polymer particles of low glass transition temperature with emulsion polymer particles of high glass transition teMperature are used.
Claim 5
Dependent Claim
30 words
An aqueous latex as recited in claim 1 in which said secondary solvent is propylens glycol used in an amount of at least 20 parts per 100 parts of polymer.
Claim 6
Dependent Claim
24 words
An aqueous latex as recited in claim 1 in which said polymer particles include emulsion polymer particles having a glass transition temperature below 25*C.
Claim 7
Dependent Claim
24 words
An aqueous latex as recited in claim 1 in which said polymer particles include emulsion polymer or emulsion copolymer containing styrene or methyl methacrylate.
Claim 8
Dependent Claim
35 words
An aqueous latex as recited in claim 1 in which said primary solvent is at least 3 parts by weight of mineral spirits per 100 parts of polymer, and said secondary solvent is propylene glycol.