Dirt pick-up resistant composition

Abstract

Water-based compositions that are resistant to dirt pickup, efflorescence, tannin bleed-through and surfactant leaching are described. The water-based composition includes a latex or water-dispersible polymer and a non-VOC UV-VIS (preferably, ultraviolet) absorber as a dirt pickup resistance additive. Methods of making water-based compositions including a non-VOC UV-VIS absorber as an additive are also described.

Claims

1. A water-based coating composition, comprising: a latex polymer formed from reactants comprising diacetone acrylamide; and methyl-o-benzoyl benzoate; wherein the latex polymer is formed from reactants comprising diacetone acrylamide in an amount of no more than 10 wt-%.

2. The composition of claim 1 wherein the latex polymer is a multi-stage latex polymer.

3. The composition of claim 2 wherein the latex polymer has at least one Tg within a range of 10 C. to 40 C.

4. The composition of claim 1 wherein methyl-o-benzoyl benzoate is present in an amount of at least 0.1 wt-% and up to 5.0 wt-%, based on the weight of the polymer solids.

5. The composition of claim 1 wherein the latex polymer is present in the coating composition in an amount of at least 10 wt-%, based on 10-25% solids of the paint for flats and 15-35% for semi-gloss paints.

6. The composition of claim 1 wherein the composition is a water-based paint, sealer, caulk, or sealant.

7. The composition of claim 6 wherein the composition is a water-based paint.

8. The composition of claim 7 wherein the composition is a water-based paint with a pigment volume concentration of 35 to 75 for a flat paint, 20 to 40 for a semi-gloss paint, and about 10 to 25 for a high gloss paint.

9. The composition of claim 7 wherein the composition is a semi-gloss paint having a paint finish that has a moderately satin-like luster and a 60 gloss rating of at least about 30 units.

10. The composition of claim 7 wherein the composition is a high-gloss paint having a paint finish that has a shiny appearance and a 60 gloss rating of at least about 70 units.

11. The composition of claim 1 wherein the composition has extractables of less than about 0.3%.

12. The composition of claim 11 wherein the composition has extractables of less than about 0.2%.

13. The composition of claim 1 wherein the composition includes no greater than 5 grams total VOC per 100 grams polymer solids.

14. The composition of claim 12 further comprising one or more low VOC coalescents having a volatile organic content of 30% or less.

15. A water-based coating composition, comprising: a multi-stage latex polymer formed from reactants comprising diacetone acrylamide; and methyl-o-benzoyl benzoate; wherein the composition includes no greater than 5 grams total VOC per 100 grams polymer solids.

16. The composition of claim 15 wherein the latex polymer has at least one Tg within a range of 10 C. to 40 C.

17. The composition of claim 15 wherein methyl-o-benzoyl benzoate is present in an amount of at least 0.1 wt-% and up to 5.0 wt-%, based on the weight of the polymer solids.

18. The composition of claim 15 wherein the latex polymer is present in the coating composition in an amount of at least 10 wt-%, based on 10-25% solids of the paint for flats and 15-35% for semi-gloss paints.

19. The composition of claim 15 wherein the latex polymer is formed from reactants comprising diacetone acrylamide in an amount of no more than 10 wt-%.

Description

EXAMPLES

(1) The invention is illustrated by the following examples. It is to be understood that the particular examples, materials, amounts, and procedures are to be interpreted broadly in accordance with the scope and spirit of the inventions as set forth herein. Unless otherwise indicated, all parts and percentages are by weight and all molecular weights are weight average molecular weight. Unless otherwise specified, all chemicals used are commercially available from, for example, Sigma-Aldrich, St. Louis, Mo.

Test Methods

(2) Unless indicated otherwise, the following test methods were utilized in the Examples that follow.

(3) A. Dirt Pickup Resistance Test

(4) Paint samples to be tested are applied to a 36 aluminum Q panel (or other appropriate substrate) using a wire wound drawdown bar (RDS) to a film thickness of about 3 mils. Each paint sample is then dried for 24 hours at room temperature (70-75 F.). Dried panels are placed outdoors or in a QUVA cabinet for one week, with some exposure to sunlight. Outdoor testing is preferred, but QUVA exposure is acceptable.

(5) The panels are then returned to the lab after one week exposure and blotted dry if necessary.

(6) A dirt slurry is prepared as follows. First, 50 grams (g) red iron oxide (R4097), 40 g yellow oxide pigment, and 10 g black iron oxide pigment are combined and hand stirred or shaken until homogenous. Then 0.5 g TAMOL 731 (Dow Chemical) is added to 200 g deionized water with agitation. The pigment combination is then slowly added and mixed for 30 minutes until a smooth slurry is formed.

(7) The slurry is applied to half of the coated panels using a foam applicator or other suitable brush, and dried on panels at room temperature for 3-4 hours.

(8) The dried slurry is then washed off each panel by running the panel under water and using a small piece of cheese cloth, rubbing lightly. A clean cloth is used for each panel. The panels are blotted dry and allowed to completely dry (2-4 hours) before measuring change in color, E, using a spectrophotometer.

(9) B. Measurement of Gloss

(10) Specular gloss ratings for paint formulations applied to test panels are measured according to the procedure described in ASTM D523-14 (Standard Method for Specular Gloss).

(11) C. Measurement of Surfactant Leaching

(12) To determine surfactant leaching, a paint is drawn down onto a black mylar chart using a 6 mil drawdown bar. The drawdown is dried for 4 hours at room temperature. 5 g of water is pipetted onto the drawdown, keeping care to apply the water in as small of a surface area as the coating allows. The water is allowed to sit for 30 minutes, after which, the water is collected and analyzed for extractables using Liquid Chromatography-Mass Spectroscopy (LC-MS).

(13) D. Measurement of Efflorescence

(14) In order to perform efflorescence testing, the white paint was tinted in a half-pint sized-can with two colorants. 248.6 grams of white paint was tinted with 24 grams of Novocolor 8544C Quinacridone Red, and 14 grams of Novocolor 8513 Yellow colorant. The tinted paints were then shaken for approximately 5 minutes. Before painting, each tinted paint was drawn down on a plain white penopac chart, using a 3 mil draw down bar, and stored in a drawer to preserve the color. The substrates used for efflorescence testing were Hardie Boards skim-coated with UGL Drylok. Once dried, the board was split off into 6 equal length sections. These sections were painted with 400 square feet per gallon amount of paint, which equated to 6 grams. After completing the first coats of each section, the board was left to dry approximately 2 hours before finishing with a second coat on each section. They were then allowed to dry at room temperature overnight and then put outside for exterior exposure the following day. The panels were exposed outside for 24 days. The panels were then brought inside and measured on a spectrophotometer, measuring a E value of the current color after being exposed, compared to its initial color, on the draw down chart taken initially.

(15) E. Measurement of Tannin Stain Blocking

(16) To evaluate the tannin stain blocking, a redwood board is painted with two coats (4 hours in between coats) of white paint. The board is allowed to dry for 1 to 2 days, after which the board is placed into a humidity cabinet for 3 days. After removal from the cabinet, the board is allowed to dry overnight and E values are measured to evaluate color change.

Example 1

Preparation of Paint Compositions

(17) Single stage latex polymer compositions were prepared by combining monomers including methacrylic acid (MAA), methyl methacrylate (MMA), n-butyl methacrylate (BMA) and/or 2-ethyl hexyl acrylate (EHA) in the amounts shown in Table 1. Emulsions #1 and #2 in Table 1 were prepared according to standard methods known to those of skill in the art. The emulsions were fed into a reactor over a three-hour time period. After polymerization was complete, a non-VOC UV absorber or photoinitiator was added to each emulsion. A white paint formulation and a clear paint formulation were prepared from the emulsions and tested for dirt pick up resistance, efflorescence, tannin bleed-through (white) and surfactant leaching (clear). The Tg values for each emulsion were measured by differential scanning calorimetry (DSC).

(18) TABLE-US-00001 TABLE 1 Polymer Compositions Measured MAA MMA BA EHA Midoint Emulsion (%) (%) (%) (%) Tg ( C.) 1 1.5 44 40.3 10 14.2 2 1.5 44 30.7 20 11.7

Example 2

Performance Testing

(19) Test paint formulations A and B were made from emulsions #1 and #2 from Example 1 and applied to 36 aluminum Q panels. The dirt pick up resistance, efflorescence and tannin bleed-through of each formulation was evaluated according to procedures described above. Four test panels were prepared and results were averaged. Surfactant leaching was assessed by measuring the amount of extractables in the water phase, specifically polyethylene glycol (PEG 400) using LC-MS. For comparison, paint formulations C and D were prepared using two commercially available all-acrylic latex polymers, Acronal OPTIVE 230 (BASF) and RHOPLEX 585 (Dow) and evaluated for the same performance characteristics.

(20) Results are reported in Table 2. Surfactant leaching is reported as a percent of extractables and dirt pickup resistance is reported as a change in color or E reading from a spectrophotometer.

(21) TABLE-US-00002 TABLE 2 Performance Testing Dirt Pick Up Resistance PEG Efflorescence Tannin Paint (E) (%) (E) (E) A 3.67 0.22 2.57 3.67 B 4.62 0.20 2.07 3.75 C 15.89 0.36 4.19 9.96 D 8.72 0.36 3.32

Example 3. Preparation of a Two-Stage Polymer Composition

(22) A two-stage latex polymer was prepared by making a first monomer emulsion including 11.5 g acrylic acid, 6.5 g methacrylic acid, 30 g diacetone acrylamide, 400 g butyl methacrylate, and 120 g methyl methacrylate. This first monomer emulsion was fed into a reactor over a two-hour time period. A second monomer emulsion including 7.6 g acrylic acid, 14 g butyl acrylate, 13 g diacetone acrylamide, and 210 g methyl methacrylate was then fed into the reactor over a one-hour time period. After polymerization was complete, a non-VOC UV absorber or photoinitiator was added to the emulsion. A paint formulation was prepared from the emulsion.

(23) The complete disclosure of all patents, patent applications, and publications, and electronically available material cited herein are incorporated by reference. The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described, for variations obvious to one skilled in the art will be included within the invention defined by the claims. The invention illustratively disclosed herein suitably may be practiced, in some embodiments, in the absence of any element which is not specifically disclosed herein.