Storage stable PCM containing aqueous cool coatings for flexible foams
The present invention provides cooling, substantially formaldehyde and alkylphenylethoxylate (APEO) free aqueous coating compositions of a soft acrylic or vinyl copolymer binder comprising from 1.8 to 5 wt. %, based on the total weight of monomers used to make the copolymer, of an ethylenically unsaturated acid functional group containing monomer, in copolymerized form, and, in copolymerized form, an adhesion promoting ethylenically unsaturated monomer; an aqueous encapsulated PCM (phase change material) having a crosslinked acrylic shell; a nonionic associative thickener, such as a polyurethane associative thickener; and a softener. The aqueous coating compositions have a pH ranging from 7 to 8 and a solids content as high as 70 wt. % and provide soft coatings for viscoelastic polyurethane foams.
1. An aqueous acrylic or vinyl coating composition comprising: a soft acrylic or vinyl copolymer binder having a calculated glass transition temperature of from −75° C. to −25° C. and comprising 1.8 to 5 wt. %, based on the total weight of monomers used to make the copolymer, of an ethylenically unsaturated acid functional group containing monomer in copolymerized form, from 0.5 to 4 wt. %, based on the total weight of monomers used to make the copolymer, of an adhesion promoting ethylenically unsaturated monomer in copolymerized form; an aqueous encapsulated PCM (Phase change material) having a crosslinked acrylic shell; from 0.05 to 1.4 wt. %, based on the total weight of the aqueous coating composition, of a nonionic associative thickener; and from 3 to 15 wt. %, based on the total weight of the aqueous coating composition, of a softener,
wherein the aqueous coating composition has a solids content of from 25 wt. % to 70 wt. %, and has a pH ranging from 7 to 8.
2. The aqueous coating composition as claimed in claim 1 , wherein the adhesion promoting ethylenically unsaturated monomer in copolymerized form is an ethylene ureido functional ethyl methacrylate monomer.
3. The aqueous coating composition as claimed in claim 1 , wherein the crosslinked acrylic shell in the aqueous encapsulated PCM is a copolymer comprising, in copolymerized form, one or more diethylenically unsaturated monomer.
4. The aqueous coating composition as claimed in claim 1 , wherein the PCM in the aqueous encapsulated PCM comprises an organic wax.
5. The aqueous coating composition as claimed in claim 1 , wherein the aqueous encapsulated PCM comprises an aqueous encapsulated PCM mixture of two or more aqueous encapsulated PCMs chosen from an aqueous PCM mixture wherein at least 10 wt. % of the aqueous PCM-mixture, as solids, is in the form of a cake, or an aqueous PCM mixture of aqueous encapsulated PCMs each having a different melting point ranging from 25 to 38° C., wherein each different melting point differs at least 1° C. from the other.
6. The aqueous coating composition as claimed in claim 1 , wherein the nonionic associative thickener is a hydrophobically modified ethoxylated urethane (HEUR).
7. The aqueous coating composition as claimed in claim 6 , wherein the HEUR has both pendant and end terminal hydrophobic groups.
8. The aqueous coating composition as claimed in claim 1 , wherein the softener is a polyalkylene glycol having a molecular weight of from 200 to 1000.
9. The aqueous coating composition as claimed in claim 1 having a solids content of from 30 wt. % to 65 wt. % and a pH ranging from 7.2 to 7.75.
10. The aqueous coating composition as claimed in claim 1 , which is substantially formaldehyde free and contain a level of alkylphenylethoxylates (APEO) s of less than 50 ppm.
11. A substrate coated with the aqueous coating composition of claim 1 , wherein the substrate is a viscoelastic foam.