High block, tack and scrub resistant polymer
View Patent ↗The present invention is directed to a coating composition or paint comprising a multistage latex with at least first and second stages, wherein the composition or paint is substantially free of volatile organic compounds (VOC) and capable of film formation even in the absence of coalescent agents. The base paint formulation is capable of being tinted at a point-of-sale (i.e. in-store) using a colorant composition of a type and quantity required to produce a paint of desired color and finish. The paints, including deeply colored paints, show improved block resistance, scrub resistance and tack resistance.
1. A coating composition, comprising:
an in-store tintable liquid base paint formulation, comprising
a multistage latex polymer having at least a first stage with a Tg of greater than about 0 to 120° C. and at least a second stage with a Tg of −35 to 0° C.; and
up to about 0.5 wt % fluorosurfactant; and
about 0.05 to 15 wt % of one or more colorant compositions having zero volatile organic content (VOC); which colorants are added to the base paint formulation at a point-of-sale to achieve a desired color,
wherein the coating composition has scrub resistance of at least about 600 scrubs,
wherein the coating composition includes at least about 1 wt % ureido-functional monomer in at least the first stage and the second stage, and
wherein the coating composition is essentially free of a separate coalescing agent.
2. The composition of claim 1 , made by a process comprising the steps of:
providing a container with a quantity of the in-store tintable base paint formulation and headspace sufficient to receive a quantity of one or more zero VOC colorants;
providing instructions for dispensing the zero VOC colorant into the base paint formulation at a point-of-sale, and in a particular amount, to obtain a coating composition of a desired color.
3. The composition of claim 1 , wherein the multistage latex polymer is made by a method comprising:
preparing a first mixture of monomers for a first stage, the first mixture comprising about 94 to 98 wt % methyl methacrylate, 1 to 3 wt % methacrylic acid, about 1 to 3 wt % ureido-functional monomer, and optionally, about 1 to 3 wt % acetoacetoxy ethyl methacrylate, based on the total weight of the monomers in the first mixture;
preparing a second mixture of monomers for a second stage, the second mixture comprising about 30 to 40 wt % methyl methacrylate, about 50 to 60 wt % butyl acrylate, about 1 to 3% methacrylic acid, about 1 to 5 wt % acetoacetoxy ethyl methacrylate, and about 1 to 3 wt % ureido-functional monomers, based on the total weight of the monomers in the second mixture;
feeding the first mixture into a reactor vessel;
initiating a free radical polymerization of at least the first mixture; and
feeding the second mixture into the reactor vessel.
4. The composition of claim 1 , wherein the multistage latex is capable of forming a film at a temperature of 4° C. or less.
5. The composition of claim 1 , wherein the multistage latex is capable of forming a film at a temperature of 10° C. or less, in the absence of a separate coalescing agent.
6. The composition of claim 3 , wherein the monomers forming the first stage or second stage comprise one or more ethylenically unsaturated monomers selected from the group consisting of acrylic acid, C 1 -C 8 esters of acrylic acid, substituted C 1 -C 8 esters of acrylic acid, methacrylic acid, C 1 -C 8 ester of methacrylic acid, substituted C 1 -C 8 esters of methacrylic acid, styrene, α-methyl styrene, vinyl toluene, vinyl acetate, vinyl propionate, allyl methacrylate, and mixtures thereof.
7. The composition of claim 3 , wherein the monomers forming the first stage or second stage further comprise one or more ureido-functional monomers.
8. The composition of claim 3 , wherein the monomers forming the first stage or second stage further comprise one or more polyfunctional acrylate monomers.
9. The composition of claim 1 , wherein the difference in Tg of the first and second stage monomers is at least about 65° C.
10. The composition of claim 1 , wherein the composition exhibits block resistance rating of at least 6.
11. The composition of claim 1 , wherein the composition exhibits tack resistance of up to about 3 s.
12. The composition of claim 1 , wherein the composition is capable of forming a film at temperature of less than about 15° C.
13. The composition of claim 1 , wherein the zero VOC colorant comprises:
a colorant component;
a surfactant package comprising at least one latex-compatible surfactant; and
a carrier.
14. The composition of claim 1 , wherein the composition comprises about 0.1 to 0.3 wt % fluorosurfactant, based on the total weight of the composition.