High opacity resin coatings

Claim 2

AN AQUEOUS LATEX COATING COMPOSITION ADAPTED TO DEPOSIT A FILM OF LOW OPACITY RESIN WHICH DRIES TO PRODUCE A CELLULAR FILM OF HIGH OPACITY AND BRIGHTNESS, CONSISTING ESSENTIALLY OF AN AQUEOUS CONTINUOUS PHASE HAVING STABLY SUSPENDED THEREIN POLYMER OF EMULSION POLYMERIZED UNSATURATED MONOMER IN THE FORM OF PARTICLES OF LOW OPACITY ORGANIC SOLVENT-SOLUBLE RESIN, SAID POLYMER PARTICLES BEING SWOLLEN BY HAVING ABSORBED THEREIN AT LEAST 5 PARTS BY WEIGHT PER 100 PARTS OF POLYMER OF A PRIMARY ORGANIC SOLVENT WHICH IS ESSENTIALLY IMMISCIBLE IN THE AQUEOUS PHASE OF SAID LATEX, AND AT LEAST 5 PARTS BY WEIGHT PER 100 PARTS OF POLYMER OF A SECONDARY WATER MISCIBLE ORGANIC SOLVENT IN SAID AQUEOUS PHASE, SAID SECONDARY ORGANIC SOLVENT BEEING A GLYCOL HAVING A LOWER EVAPORATION RATE THAN SAID PRIMARY SOLVENT AND A LESSER CAPACITY FOR SOLVATING SAID POLYMER, SAID COMPOSITION FURTHER INCLUDING AN ORGANIC SOLVENT SOLUBLE OPTICAL BRIGHTENER OR FLUORESCENT AGENT DISSOLVED IN SAID PRIMARY ORGANIC SOLVENT AND ABSORBED THEREWITH IN SAID POLYMER PARTICLES WHEREBY, WHEN SAID LATEX IS DEPOSITED AND DRIED, SAID SOLVENTS WILL EVAPORATE TO PRODUCE A FILM HAVING A CONTRAST RATIO OF AT LEAST ABOUT 0.7 IN THE ABSENCE OF PIGMENT AND SAID OPTICAL BRIGHTENER OR FLUORESCENT AGENT WILL BE RETAINED WITHIN THE BODY OF THE FILM.

Claim 3

An aqueous latex as recited in claim 1 in which said latex is substantially devoid of pigment.

Claim 4

An aqueous latex as recited in claim 1 in which said primary organic solvent is used in an amount of from about 20 to about 80 parts per 100 parts of polymer.

Claim 5

An aqueous latex as recited in claim 3 in which said glycol is propylene glycol.

Claim 6

An aqueous latex as recited in claim 3 in which said primary organic solvent is aromatic.

Claim 7

An aqueous latex coating as recited in claim 1 in which said polymer particlEs have a glass transition temperature below 25*C. and said solvent-swollen polymer particles have an average diameter of at least about 0.5 micron.

Claim 8

An aqueous latex as recited in claim 1 in which said polymer particles are a mixture of particles of polymer having a glass transition temperature below 25*C. and particles of polymer having a glass transition temperature above 30*C.

Claim 9

An aqueous latex as recited in claim 1 in which said water immiscible organic solvent has solvent-soluble dye dissolved therein.

Claim 10

An aqueous latex as recited in claim 1 in which said optical brightener or fluorescent agent is present in an amount of from 0.1-2% of the weight of the polymer particles.

Claim 11

An aqueous latex as recited in claim 2 in which a film formed from the latex has a contrast ratio of at least 0.8.

Claim 12

An aqueous latex coating composition adapted to deposit a water resistant film of low opacity resin which dries to produce a cellular film of high opacity and brightness, consisting essentially of an aqueous continuous phase having stably suspended therein polymer particles of low opacity organic solvent-soluble resin, said polymer particles being swollen by having absorbed therein at least 5 parts by weight, per 100 parts of polymer of a primary organic solvent which is essentially immiscible in the aqueous phase of said latex, said polymer particles being a mixture of particles of polymer having a glass transition temperature below 25*C. and particles of polymer having a glass transition temperature above 30*C., said polymer particles being aqueous emulsion polymers of monoethylenic monomers, and at least 5 parts by weight, per 100 parts of polymer, of a secondary water miscible organic solvent in said aqueous phase, said secondary organic solvent being a glycol having a lower evaporation rate than said primary solvent and a lesser capacity for solvating said polymer, said composition being substantially devoid of pigment and further including from 0.1-2% of the weight of the polymer of an organic solvent soluble optical brightener or fluorescent agent dissolved in said primary organic solvent and absorbed therewith in said polymer particles whereby, when said latex is deposited and dried, said solvents will evaporate to produce a water resistant film having a contrast ratio of at least about 0.8 in the absence of pigment and said optical brightener or fluorescent agent will be retained within the body of the film.

Claim 13

An aqueous latex coating composition adapted to deposit a water resistant film of low opacity resin which dries to produce a cellular film of high opacity and brightness, consisting essentially of an aqueous continuous phase having stably suspended therein polymer particles of low opacity organic solvent-soluble resin, said polymer particles being swollen by having absorbed therein at least 5 parts by weight, per 100 parts of polymer of a primary organic solvent which is essentially immiscible in the aqueous phase of said latex, said polymer particles being a mixture of particles of polymer having a glass transition temperature below 25*C. and particles of polymer having a glass transition temperature above 30*C., said polymer particles being aqueous emulsion polymers of monoethylenic monomers, and at least 5 parts by weight, per 100 parts of polymer, of a secondary water miscible organic solvent in said aqueous phase, said secondary organic solvent being a glycol having a lower evaporation rate than said primary solvent and a lesser capacity for solvating said polymer, said composition being substantially devoid of pigment and further including from 0.1-2% of the weight of the polymer of an organic solvent soluble optical brightener or fluorescent agent dissolved in said primary organic solvent and absorbed therewith in said polymer particles whereby, when said latex is deposited and dried, said solvents will evaporate to produce a water resistant film having a contrast ratio of at least about 0.8 in the absence of pigment and said optical brightener or fluorescent agent will be retained within the body of the film.

Claim 14

An aqueous latex as recited in claim 11 in which said primary organic solvent is aromatic, and said glycol is propylene glycol.