AQUEOUS COATING COMPOSITIONS HAVING LOW OR ZERO VOCS AND COMPRISING ENCAPSULATED OR POLYMER ADSORBED PIGMENTS AND LETDOWN BINDERS

Abstract

The present invention provides aqueous compositions useful as zero VOC coating compositions having a % opacifying pigment volume concentration (% OPVC) of from 2 to 25 and comprising (i) an opacifier composition of an at least partially polymer encapsulated opacifying pigment, a polymer opacifying pigment composite or their mixtures, with the opacifying pigment, encapsulated in and/or as a composite with at least one soft polymer having a measured glass transition temperature (measured Tg) of 5° C. or less, and (ii) a hard binder polymer having a measured Tg of at least 30° C. and a weight average particle size of 120 nm or less, wherein the ratio of the weight average particle size of the opacifier composition to that of the hard binder polymer is from 2:1 to 12:1 and the volume ratio of the opacifying pigment to the soft polymer solids in the opacifier composition is from 2:5 to 1:1

Claims

1. An aqueous composition having a % opacifying pigment volume concentration (% OPVC) of from 2 to 25 comprising (i) at least one opacifier composition in the form of particles chosen from an at least partially polymer encapsulated opacifying pigment, a polymer opacifying pigment composite and their mixtures, the opacifying pigment, encapsulated in and/or as a composite with at least one soft polymer having a measured glass transition temperature (measured Tg) of 5° C. or less, and (ii) a hard binder polymer having a measured Tg of at least 30° C., or, preferably, at least 50° C., wherein the hard binder polymer has a weight average particle size of 120 nm or less, further wherein, the ratio of the weight average particle size of the opacifier composition to that of the hard binder polymer is from 2:1 to 12:1 and, still further wherein the volume ratio of the opacifying pigment to the soft polymer solids in the opacifier composition is from 2:5 to 1:12.

2. The aqueous composition as claimed in claim 1 having a % OPVC 20 or less.

3. The aqueous composition as claimed in claim 1, wherein the opacifying pigment in the (i) at least one opacifier composition comprises titanium dioxide (TiO.sub.2).

4. The aqueous composition as claimed in claim 1, wherein the soft polymer in the (i) at least one opacifier composition has a measured Tg of 0° C. or less.

5. The aqueous composition as claimed in claim 1, wherein the (ii) hard binder polymer has a measured Tg of at least 50° C.

6. The aqueous composition as claimed in claim 1, wherein the (i) at least one opacifier composition has a weight average particle size of 260 nm to 1500 nm.

7. The aqueous composition as claimed in claim 1, wherein the soft polymer in the (i) opacifier composition and the (ii) hard binder polymer are each emulsion copolymers.

8. The aqueous composition as claimed in claim 1, wherein the opacifying pigment in the (i) opacifier composition has an index of refraction [nD (20° C.)] that is at least 1.8.

9. The aqueous composition as claimed in claim 8, wherein the opacifying pigment in the (i) opacifier composition comprises titanium dioxide (TiO.sub.2).

10. A methods of making the aqueous composition as claimed in claim 1, comprising providing an aqueous composition of at least one opacifying pigment having an having a weight average particle size of at least 150 nm to 1200 nm, (i) forming an opacifier composition by one of 1) aqueous emulsion copolymerizing a monomer mixture to form soft polymer in the presence of the aqueous composition of the at least one opacifying pigment to form an at least partially soft polymer encapsulated opacifying pigment, 2) combining an aqueous composition of a phosphorus acid group containing soft polymer with the aqueous composition of the at least one opacifying pigment to form a polymer opacifying pigment composite, or 3) their combination; and (ii) combining the opacifier composition with a hard binder polymer to form an aqueous composition having a % opacifying pigment volume concentration (% OPVC) of from 2 to 25.

Description

EXAMPLES

[0069] The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0070] Abbreviations (except as further noted, below): SDS=Sodium dodecylbenzene sulfonate (23 wt. %); BA=Butyl acrylate; SSS=Sodium styrene sulfonate; EHA=Ethylhexyl acrylate; MMA=Methyl methacrylate; BHP=i-Butyl hydroperoxide; MAA=Glacial methacrylic acid; EDTA=Ethylene diamine tetraacetic acid; ALMA=Allyl methacrylate; IAA=Isoascorbic acid; DI=Deionized; PEM=Phosphoethyl methacrylate (65 wt. % active); AAEM=Acetoacetoxyethyl methacrylate; AA=Acrylic Acid; AN=Acrylonitrile; P-acid=phosphorus acid group containing.

[0071] The soft polymers 1 and 2 presented in Table 1, below, and the hard polymers presented in Table 2, below were used to make polymer opacifying pigment composites in accordance with the present invention. The soft polymers 3 and 4 presented in Table 1, below are comparatives. The polymer 1B presented in Table 3, below, is a soft/hard two-stage acrylic polymer.

TABLE-US-00001 TABLE 1 Soft Polymers For Making Polymer Opacifying Pigment Composites PS Tg Example Composition Solids pH (nm) (° C.) Soft 63 EHA/33.8 MMA/3.2 PEM 42.8% 9.46 74.8 −20 Polymer 1 Soft 63 EHA/33.8 MMA/3.2 PEM 42.9% 9.53 108.8 −21 Polymer 2 Soft 63 EHA/35 MMA/2.0 AA 42.5% 9.36 71.5 −19 Polymer 3 Soft 63 EHA/35 MMA/2.0 AA 42.9% 9.39 111.6 −19 Polymer 4

TABLE-US-00002 TABLE 2 Hard Polymers PS Tg Example Composition Solids pH (nm) (° C.) Hard Styrene/EHA/MMA/MAA   45% 7.5 80 35 Polymer 1.sup.1 Hard Styrene/EHA/AN/MAA 41.5% 7.6 80 52 Polymer 2.sup.2 .sup.1Aqueous styrene-acrylic emulsion polymer with 5 wt. % or less copolymerized acid mer content; .sup.2Aqueous styrene-acrylic emulsion polymer with 5 wt. % or less copolymerized acid mer content.

TABLE-US-00003 TABLE 3 Soft/Hard Two Stage Comparative Binder Polymer Example Composition % T.S. pH PS (nm) Polymer 1B .sup.1 Styrene/EHA/MMA/ 50-51% 8.50-9.50 120-150 AAEM/PEM .sup.1 Aqueous acrylic two-stage emulsion polymer with 60% polymerization stage comprising of Styrene/EHA/MMA/AAEM/PEM (calculated Tg = 11° C.), and 40% polymerization stage comprising of Styrene/EHA/MMA/AAEM/PEM (calculated Tg = 35° C.). Tgs of the polymers are calculated so that for calculating the Tg of a copolymer of monomers M1 and M2, the calculated Tg = w (M1) × Tg(M1) + w(M2) × Tg(M2) wherein the calculated Tg is the glass transition temperature calculated for the copolymer, w(M1) is the weight fraction of monomer M1 in the copolymer, w(M2) is the weight fraction of monomer M2 in the copolymer, Tg(M1) is the glass transition temperature of the homopolymer of M1, Tg(M2) is the glass transition temperature of the homopolymer of M2, all temperatures being in Kelvin and then converted after calculation to ° C.

Soft Polymer 1 Synthesis Example

[0072] To 1350 g of deionized (DI) water under a nitrogen atmosphere at 87° C. was added 35.5 g of anionic surfactant A (31 wt. % active ethoxylated (EO) alkyl ether sulfate C.sub.12-14 with, sodium salt, CAS-NO. 68891-38-3; from BASF as in Example 1 of EP publication EP2426166 A2), 45 g DI water, 60.5 g of monomer mixture 1, 6.5 g of ammonium persulfate dissolved in 50 g DI water to form a reaction mixture. The remaining monomer mix 1, shown in the Table, below, was added over 110 minutes along with a solution of 2.8 g ammonium persulfate dissolved in 75 g DI water. At the end of the polymerization, 19.8 g of 30% ammonium hydroxide solution, 0.01 g FeSO.sub.4 in 10 g DI water, 0.02 g of EDTA in 1.5 g of DI water, 2.1 of t-butylhydroperoxide dissolved in 40 g of DI water, and 1.5 g of isoascorbic acid dissolved in 40 g of DI water were added. An additional 34.2 g of 30% ammonium hydroxide was added to raise the pH to 9.46. The resulting soft polymer 1 had a solids content of 42.3% and a particle size of 75 nm.

TABLE-US-00004 TABLE Monomer Mixture 1 ingredient grams DI water 450.00 Anionic surfactant A (31% active) 36.50 2-ethylhexyl acrylate 1071.00 Methyl methacrylate 574.60 Phosphoethyl methacrylate 34

Soft Polymer 2 Synthesis Example

[0073] Was prepared as in the soft polymer 1 synthesis example, except the amount of Fes 32 added to the reaction mixture was 3.6 g. Monomer mixture 2 is shown in the Table, below. The resulting polymer had a solids content and a particle size as shown in Table 1, above.

TABLE-US-00005 TABLE Monomer Mixture 2 Ingredient grams DI water 450.00 Anionic surfactant A (31% active) 68.4 2-ethylhexyl acrylate 1071.00 Methyl methacrylate 574.60 Phosphoethyl methacrylate 34

Soft Polymer 3 Synthesis Example

[0074] To 1350 g of deionized (DI) water under a nitrogen atmosphere at 87° C. was added 35.5 g of Anionic surfactant A (31% active), 45 g DI water, 60.5 g of monomer mixture 3, 6.5 g of ammonium persulfate dissolved in 50 g DI water to form a reaction mixture. The remaining monomer mix 3, shown in the Table, below, was added over 110 minutes along with a solution of 2.8 g ammonium persulfate dissolved in 75 g DI water. At the end of the polymerization, 19.8 g of 30% ammonium hydroxide solution, 0.01 g FeSO.sub.4 in 10 g DI water, 0.02 g of EDTA in 1.5 g of DI water, 2.1 of t-butylhydroperoxide dissolved in 40 g of DI water, and 1.5 g of isoascorbic acid dissolved in 40 g of DI water were added. An additional 15 g of 30% ammonium hydroxide was added to raise the pH to 9.36. The resulting polymer had a solids content and a particle size as shown in Table 1, above.

TABLE-US-00006 TABLE Monomer mixture 3 Ingredient grams DI water 450.00 Anionic surfactant A (31% active) 36.50 2-ethylhexyl acrylate 1071.00 Methyl methacrylate 595 acrylic acid 34

Soft Polymer 4 Synthesis Example

[0075] The soft polymer 4 was prepared in a similar manner to the soft polymer 3, except that the amount of Fes 32 added to the reaction mixture was 3.6 g. The monomer mixture 4 is shown in the Table, below. The resulting polymer had a solids content and a particle size as shown in Table 1, above.

TABLE-US-00007 TABLE Monomer Mixture 4 Ingredient grams DI water 450.00 Anionic surfactant A (31% active) 68.40 2-ethylhexyl acrylate 1071.00 Methyl methacrylate 595 Acrylic acid 34

[0076] As shown in Tables 4 and 5, below, the indicated polymers as disclosed in the Tables, above, are formulated into Inventive and Comparative coating formulations by letting the ingredients down in the indicated binder polymer. To make the coating formulation in Table 4, below, an IKA RW 16 basic overhead stirrer (IKA Works, Inc., Wilmington, N.C.) was used. The binder polymer, water and BYK-028 defoamer were combined using the overhead stirrer. TiPure™ R-746 rutile titanium dioxide (DuPont, Wilmington, Del.) slurry was added into the polymer emulsion mixture while stirring using the overhead stirrer and stirred for 10 min. The coalescent, sodium nitrite (15% w/w in water), ACRYSOL™ RM-2020NPR rheology modifier, and ACRYSOL™ RM-8W rheology modifier were added in sequence under stirring. To make the coating formulation in Table 5, below, the binder polymer, water and defoamer were combined under agitation using an IKA RW 16 basic overhead stirrer and TiO.sub.2 (TiPure™ R-746, DuPont) rutile titanium dioxide slurry in the amount needed to give the indicated % OPVC in Table 5 was added into the polymer emulsion mixture while stirring using the overhead stirrer and stirred for 10 min. The hard polymer, sodium nitrite (15% w/w in water), ACRYSOL™ RM-2020NPR rheology modifier, and ACRYSOL™ RM-8W rheology modifier were subsequently added under stirring. In the coating formulations of Table 5, a plurality of the indicated soft polymer particles adsorbed onto a TiO.sub.2 particle to make a polymer opacifying pigment composite.

TABLE-US-00008 TABLE 4 Coating Formulation For The Comparative Polymer Binder Example 19C weight Material Name (lb) Polymer 1B (two-stage soft-hard binder polymer) 50.12 Aqua ammonia 15% w/w 0.25 BYK-028 Defoamer.sup.1 (Mixture of polysiloxane and hydrophobic 0.10 solids in polyglycol) TiPure ™.sup., 2 R-746 Rutile titanium dioxide slurry 26.99 (76.5 w/w % in water) Texanol ™.sup., 3 ester alcohol (2,2,4-trimethyl-1,3- 0.76 pentanediol mono(2-methylpropanoate) Dowanol ™.sup., 4 DPM (Dipropylene glycol monomethyl ether) 2.28 Sodium Nitrite (15% w/w in water) 0.89 ACRYSOL ™.sup., 4 RM -2020NPR Rheology Modifier, 0.75 hydrophobically modified ethylene oxide urethane (HEUR) polymers ACRYSOL ™.sup., 4 RM -8W Rheology Modifier, hydrophobically 0.16 modified ethylene oxide urethane (HEUR) polymers Water 17.71 Total 100 Total % OPVC 18 Volume Solids 35 Weight Solids 46 VOC Generic Water Excl. 95/l .sup.1BYK-Chemie GmbH, Germany .sup.2 Rutile Titanium Dioxide Slurry (weight average particle size 285 nm, DuPont, Wilmington, DE); .sup.3 Eastman Chemicals, Kingsport TN; .sup.4 The Dow Chemical Company, Midland, MI.

TABLE-US-00009 TABLE 5 Coating Formulations Material or Example Property 1 2 3C 4C 5 6 7C 8C % OPVC 18 18 18 18 18 18 18 18 % Volume Solids 35 35 35 35 35 35 35 35 % Weight Solids 47 47 47 47 47 47 47 47 VOC Generic (g/l) 0 0 0 0 0 0 0 0 (Excl. Water) Soft Polymer 1 35.76 35.71 Soft Polymer 2 35.68 35.65 Soft Polymer 3 36.01 35.87 Soft Polymer 4 35.68 35.56 TiO.sub.2 26.67 26.68 26.67 26.68 26.64 26.66 26.58 26.59 Hard Polymer 1 23.49 23.49 23.49 23.49 Hard Polymer 2 25.61 25.62 25.54 25.55 Defoamer 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 Sodium Nitrite 0.88 0.88 0.88 0.88 0.93 0.88 0.98 0.90 (15% w/w in water) Acrysol ™ RM- 0.71 0.71 0.70 0.71 0.79 0.80 0.79 0.79 2020 NPR Rheology Modifier Acrysol ™ RM-8W 0.20 0.20 0.20 0.20 0.27 0.24 0.44 0.49 Rheology Modifier Water 12.20 12.27 11.96 12.27 9.95 10.05 9.73 10.02 Total 100 100 100 100 100 100 100 100

[0077] The resulting aqueous coating compositions were made into coatings on chromate pre-treated aluminum panels using a 254 micron polytetrafluoroethylene latex film applicator, and allowed to dry in a controlled temperature room (CTR) having a set temperature of 22° C., 50% relative humidity (RH) and a pressure of 1 atm (atmospheric pressure). The resulting coatings were tested as follows:

[0078] Test Methods:

[0079] Gloss:

[0080] Gloss at the indicated angle was measured using micro-TRI-gloss meter from BYK Gardner (BYK-Gardner GmbH, Germany) after 1 day (24 hr) of drying the indicated coating in the CTR. Each value reported herein is the average of three measurements on different positions of the same coating on the same date.

[0081] Hardness:

[0082] Pendulum (König) hardness was measured on the indicated coatings according to ASTM D4366-95 (1995) using a TQC SP0500 Pendulum Hardness Tester (TQC-USA Inc., Metamora, Mich.). The films were dried in a CTR for 1 day and 7 days before the pendulum hardness measurements. The results were reported in seconds. A higher number means higher pendulum hardness.

[0083] Block Resistance:

[0084] This was measured after drying 1 day or 7 days in the controlled temperature room (CTR), pairs of 3.81 cm squares were cut from each coating, placed face-to-face and tested in one of two ways: a) overnight at room temperature in the CTR and b) ½ h in a 50° C. oven. In each test, a #8 stopper and 1 kilogram weight were placed on top of the squares. The ratings are based on the ease of separating the squares from each other and the damage on the coated surface after the separation. The ratings range from 0 to 10 with 0 being the worst, where the squares cannot be separated without completely damaging them film; and 10 being the best, where the squares can be separated without any force after the 1 kg weight is removed. A block resistance value of 6 or higher is acceptable.

[0085] Minimum Film Formation Temperature (MFFT):

[0086] The MFFT of a given material was determined using a Rhopoint MFFT instrument (Rhopoint Instruments, UK). A 2.54 cm (one inch) cube Sheen Film Applicator with a gap size of 381 microns (15 mils) was used to drawdown films on Scotch™ tape (3M, Minneapolis, Minn.) placed over a temperature gradient plate. The visual MFFT was determined as the lowest temperature at which there is no visual cracking and/or powdery appearance of film. The mechanical MFFT was determined as the temperature at which the continuous cracking of the film starts when slowly pulling the tape perpendicularly to the plate from the high temperature end.

TABLE-US-00010 TABLE 6A Coating Performance MFFT (visual/ % mechan- Example Formulation OPVC VOC ical) (° C.) 19C Polymer 1B Soft-hard 18 94 <0/5.7 2-stage  1 Hard Polymer 1 P-acid 18 0 <0/7.sup.   2 Hard Polymer 1 P-acid 18 0 <0/7.6  3C Hard Polymer 1 Non P-acid 18 0 <0/8.2  4C Hard Polymer 1 Non P-acid 18 0 <0/5.6

TABLE-US-00011 TABLE 6B Coating Performance König König Hard- Hard- RT Hot RT Hot ness, ness, block, block, block, Block, 20° 60° Example 1 day 7 day 1 day 1 day 7 day 7 day Gloss Gloss 19C 10.0 18.6 3 2 8 3 69 84  1 11.4 15.6 6 3 8 4 53 80  2 12.9 17.0 6 2 8 3 58 80  3C 14.3 16.9 7 3 8 3 37 72  4C 14.3 17.7 7 2 8 3 31 69

[0087] As shown in Tables 6A and 6B, above, a two-stage binder with soft and hard polymer stages was chosen for comparative Example 19C. However, this polymer (polymer 1B) requires a relatively high level of coalescent to formulate, around 100 g/L. The inventors were able to achieve similar or better performance at zero VOC. Both of the inventive Examples 1 and 2 containing polymer opacifying pigment composites with hard binder polymers showed dramatically improved early room temperature block resistance (1 day after coating) and from a 14% (Example 1) to a 29% (Example 2) improvement in 1 day (early) König hardness. Examples 3C and 4C contain the same amount of soft polymer, opacifying pigment, and hard polymer as Examples 1 and 2, but the soft polymers did not absorb onto TiO.sub.2 particles to form composite. The resulting paints had much lower gloss compared to Examples 1 and 2 that contain polymer opacifying pigment composites. The Comparative composition contained the same amount of opacifying pigment as the inventive compositions and the same overall amount of one polymer having a soft stage and a hard stage (SHE polymer).

TABLE-US-00012 TABLE 6C Coating Performance MFFT (visual/ % mechan- Example Polymer OPVC VOC ical) (° C.) 19C Polymer 1B 2-stage 18 94 <0/5.7  5 Hard Polymer 2 P-acid 18 0 <0/2.0  6 Hard Polymer 2 P-acid 18 0 <0/2.6  7C Hard Polymer 2 Non P-acid 18 0 <0/1.0  8C Hard Polymer 2 Non P-acid 18 0 <0/<0 

TABLE-US-00013 TABLE 6D Coating Performance König König Hard- Hard- RT Hot RT Hot ness, ness, block, block, block, Block, 20° 60° Example 1 day 7 day 1 day 1 day 7 day 7 day Gloss Gloss 19C 10.0 18.6 3 2 8 3 69 84  5 15.8 20.0 8 7 9 8 39 71  6 17.2 21.4 9 7 9 8 31 66  7C 17.2 21.5 8 7 9 8 14 54  8C 15.7 20.0 9 5 9 8 16 55

[0088] As shown in Tables 6C and 6D, above, both of the inventive Examples 5 and 6 containing polymer opacifying pigment composites with hard binder polymers showed dramatically improved early room temperature and hot block resistance (1 day after coating) and from 58% (Example 5) to 72% (Example 6) improvements in 1 day (early) König hardness. Examples 7C and 8C contain the same amount of soft polymer, opacifying pigment, and hard polymer as Examples 5 and 6, but the soft polymers did not absorb onto the TiO.sub.2 particles to form composites. The resulting paints have much lower gloss compared to inventive Examples 5 and 6 that contain polymer opacifying pigment composites. The comparative compositions contained the same amount of the same amount of opacifying pigment as the inventive compositions (Examples 5-6). The inventive compositions contained a preferred hard binder polymer having a measured Tg of 52° C.

Synthesis Example 5: Preparation of Polymer Encapsulated TiO.SUB.2 .Particles

[0089] To a 5-liter four-necked round bottom flask equipped with paddle stirrer, N.sub.2-inlet, reflux condenser, heating mantel, and thermocouple was charged 1972.5 g of a TiO.sub.2 (weight average particle size of 285 nm) amphoteric polymer slurry (prepared essentially as described in U.S. Pat. Pub. 2010/0298483A1, Example 1; 73 wt. % solids). The mixture was heated to 50° C. while purged with N.sub.2, and to the flask was sequentially added each of a solution of SDS (15 g) mixed in DI water (36.5 g), a solution of SSS (12 g in 45.5 g DI water), an aqueous solution of 0.15 wt. % aqueous iron(II) sulfate solution (25.5 g), and a 1 wt. % aqueous EDTA solution (0.98 g). Co-feed #1 (15 g BHP dissolved in 204 g DI water) and co-feed #2 (8.4 g IAA dissolved in 204 g DI water) were fed to the flask at a rate of 2 g/min. Two minutes after the onset of the co-feed additions, a monomer emulsion (ME, prepared by mixing DI water (237.8 g), SDS (27.8 g), EHA (594.8 g), MMA (456.8 g), and MAA (10.5 g)) was fed to the reactor at a rate of 17.7 g/min and allow the flask temperature to exotherm to 68° C. After the ME addition was complete, the monomer emulsion vessel was rinsed with 54.8 g deionized water into the flask. The co-feed additions were continued for another 25 min until completion. When the flask was then cooled to 45° C., aqua ammonia (14.3 g, 28% w/w) was added. After cooling to room temperature, the contents were filtered to remove any gel. The filtered dispersion was found to have a solids content of 60.1% and 27 ppm of dry gel.

[0090] The Polymer encapsulated opacifying pigments 9-11, shown in Table 7, below, were synthesized using the method as described in Synthesis Example 5 above. The EHA vs. MMA ratio and TiO.sub.2 to monomer ratio were varied according to Table 7.

TABLE-US-00014 TABLE 7 Polymer Encapsulated Opacifying Pigments TiO.sub.2 to soft Soft Polymer polymer Particle Shell Shell volume Tg.sup.1 Size.sup.2 Example Composition ratio (° C.) (nm) % T.S. pH  9 56 2-EHA/43 1:3 −2.7 454 60.1 8.8 MMA/1 MAA 10 63 2-EHA/36 1:3 −15.8 459 60.1 8.8 MMA/1 MAA 11 56 2-EHA/43 1:2 −1.7 409 61.4 8.6 MMA/1 MAA 12 63 2-EHA/36 1:2 −15.5 414 61.2 8.6 MMA/1 MAA .sup.1Measured Tg; .sup.2Particle sizes were determined using the weight average particle size of TiO.sub.2 (285 nm) and the volume ratio of TiO.sub.2 to soft polymer encapsulant, assuming that all particles are spherical and assuming uniform shell thickness.

Synthesis Example 6: Preparation of Control Soft Polymers

[0091] To a 5-L four-necked round bottom flask equipped with paddle stirrer, N.sub.2-inlet, reflux condenser, heating mantel, and thermocouple was charged 400 g of DI water. The content of the flask was heated to 50° C. while purged with N2, and to the flask was sequentially added a solution of sodium bicarbonate (3.3 g in 25 g DI water), 91.5 g of a 44.5% solids content polymer preformed emulsion with a 100 nm particle size, and a aqueous solution of 0.15% iron(II) sulfate solution (38 g). Co-feed #1 (22.6 g BHP dissolved in 215 g DI water) and co-feed #2 (12.7 g IAA dissolved in 2354 g DI water) were fed to the flask at a rate of 1.6 g/min. Two minutes after the onset of the co-feed solution addition, a monomer emulsion (ME, prepared by mixing DI water (250 g), SDS (63.7 g 23% solution), EHA (912.1 g), MMA (700.4 g), and MAA (16.3 g)) was fed to the reactor at a rate of 8.8 g/min. 10 minutes after the start of monomer emulsion fed, the feed rate was increased to 17.7 g/min, the flask temperature was allowed to exotherm to 68° C. After the ME addition was complete, the monomer emulsion vessel was rinsed with 30 g deionized water into the flask. The co-feed additions were continued for another 25 min until completion and the flask was let cool. When the flask was cooled to 30° C., 4.6 g aqua ammonia (28% w/w) was added dropwise. After cooling to room temperature, the contents were filtered to remove any gel. The filtered dispersion was found to have a particle size of 319 nm, solids content of 55.4%, pH of 8.58, and 10 ppm of dry gel.

[0092] The control polymer 2C and 3C, shown in Table 8, below, were synthesized using the methods described in Synthesis Example 6 above. The EHA vs. MMA ratios were varied according to Table 8.

TABLE-US-00015 TABLE 8 Control Soft Polymers Particle Tg Size % Example Composition (° C.) (nm) T.S. pH Polymer 2C 56 2-EHA/43 MMA/1 MAA −2.5 319 55.4 8.5 Polymer 3C 63 2-EHA/36 MMA/1 MAA −10.7 320 55.2 8.5

[0093] The polymer 1E shown in Table 9, below, was synthesized by conventional emulsion polymerization as in Example A1 of U.S. Pat. No. 8,653,180 B2.

TABLE-US-00016 TABLE 9 Hard Binder Polymers Particle Measured Size % Example Composition Tg (° C.) (nm) T.S. pH Polymer 1E Styrene/EHA/MMA/ 35 75 45.4 9.4 AAEM/PEM

[0094] As shown in Tables 10, 11, and 12, below, the indicated polymers are formulated into Inventive and Comparative coating formulations by letting the ingredients down in the indicated binder polymer. Polymer encapsulated opacifying pigments 9 and 10 can be formulated with indicated hard polymers at 0 VOC and 18% OPVC, and resulting paint showed low MFFT (<10° C.). On the other hand, the polymer encapsulated opacifying pigments 11 and 12 formulated with hard polymers at 0 VOC and 18% OPVC would require ˜100 g/L VOC to get good film formation. To make the coating formulations an IKA RW 16 basic overhead stirrer (IKA Works, Inc., Wilmington, N.C.) was used.

TABLE-US-00017 TABLE 10 Coating Formulations with Hard Polymer 1 Example Material or Property 15 16C 17 18C % OPVC 18.00 18.00 18.00 18.00 Volume Solids 35.00 35.00 35.00 35.00 Weight Solids 46.79 46.69 46.79 46.69 VOC Generic (g/l) (Excl. 0 0 0 0 Water) Polymer Encapsulated 60.08 Opacifying Pigment 9 Polymer Encapsulated 60.08 Opacifying Pigment 10 Hard Polymer 1 22.79 22.84 22.78 22.83 Defoamer (BYK-028) 0.10 0.10 0.10 0.10 TiO.sub.2 (TiPure ™ R-746) 26.77 26.77 Polymer 2C 27.98 Polymer 3C 28.08 Sodium Nitrite (15 w/w 0.88 0.88 0.88 0.88 in water) Water 15.05 20.44 15.04 20.12 Aqua Ammonia (15 wt. %) 0.11 0.00 0.11 0.19 Acrysol ™ RM-2020 NPR 0.78 0.79 0.78 0.79 Rheology Modifier (HEUR) Acrysol ™ RM-8W 0.20 0.20 0.23 0.24 Rheology Modifier (HEUR) Total Weight 100 100 100 100

TABLE-US-00018 TABLE 11 Coating Formulations with Hard Polymer 2 Example Material or Property 22 23 26C 27C % OPVC 18 18 18 18 Volume Solids 35 35 35 35 Weight Solids 46.86 46.86 46.77 46.77 VOC Generic (g/l) (Excl. Water) 0 0 0 0 Polymer Encapsulated Opacifying 60.03 Pigment 9 Polymer Encapsulated Opacifying 60.04 Pigment 10 Hard Polymer 2 24.90 24.91 24.96 24.78 BYK-028 Defoamer 0.10 0.10 0.10 0.10 TiPure ™ R-746 TiO.sub.2 26.76 26.76 Polymer 2C 27.94 Polymer 3C 28.18 Sodium Nitrite (15% w/w in water) 0.88 0.88 0.88 0.88 Water 12.73 12.74 17.98 17.93 Aqua Ammonia (15 wt. %) 0.27 0.28 0.25 0.25 Acrysol RM-2020 NPR Rheology 0.79 0.79 0.84 0.84 Modifier.sup.1 Acrysol RM-8W Rheology 0.29 0.26 0.29 0.29 Modifer.sup.1 Total Weight 100 100 100 100 .sup.1HEUR polymer

TABLE-US-00019 TABLE 12 Coating Formulations with Polymer 1E Example Material or Property 20 21 24C 25C PVC 18 18 18 18 Volume Solids 35 35 35 35 Weight Solids 47.08 47.08 46.99 46.99 VOC Generic (g/l) (Excl. Water) 0 0 0 0 Pigment 9 59.77 Pigment 10 59.77 Binder 1E 23.88 23.88 23.96 24.01 BYK-028 Defoamer 0.10 0.10 0.10 0.10 TiPure ™ R-746 TiO.sub.2 26.63 26.63 Polymer 2C 27.78 Polymer 3C 27.84 Sodium Nitrite (15% w/w in water) 0.88 0.88 0.88 0.88 Water 14.21 14.18 19.36 19.25 Aqua Ammonia (15 wt. %) 0.24 0.27 0.24 0.24 Acrysol RM-2020 NPR Rheology 0.78 0.78 0.81 0.81 Modifier.sup.1 Acrysol RM-8W Rheology 0.15 0.15 0.23 0.22 Modifer.sup.1 Total Weight 100 100 100 100 2. HEUR polymer

[0095] As shown below in Tables 13A and B, below, binder Polymer 1B requires a relatively high level of coalescent to formulate, around 100 g/L. The inventors were able to achieve similar or better performance at zero VOC. In particular, the 1-day König hardness and room-temperature block resistance are much better in Examples 15 and 17 when compared to Example 19C. Example 16C and 18C controls are blends of soft and hard polymers with TiO.sub.2, which shows much lower gloss than the invention and is not practical for real application.

TABLE-US-00020 TABLE 13A Performance In Comparison With Soft-Hard 2-stage (SHE) Polymers and Blends MFFT (visual/ % VOC mechan- Example Material OPVC (g/l) ical) (° C.) 15 Polymer Encapsulated 18 0 <0/9.sup.  Opacifying Pigment 9 + Hard Polymer 1 16C TiO.sub.2 + Polymer 2C + Hard 18 0 <0/2.3 Polymer 1 17 Polymer Encapsulated 18 0 <0/3.4 Opacifying Pigment10 + Hard Polymer 1 18C TiO.sub.2 + Polymer 3C + Hard 18 0 <0/2.3 Polymer 1 19C* Polymer 1B (SHE polymer) 18 94 <0/<0 

TABLE-US-00021 TABLE 13B Performance In Comparison With SHE Polymers and Blends König König Hard- Hard- RT Hot RT Hot ness ness block block block Block 20° 60° Example 1 day 7 day 1 day 1 day 7 day 7 day Gloss Gloss 15 23.1 21.6 8 3 8 2 60 81 16C 21.6 21.1 7 3 8 3 11 52 17 17.2 16.6 7 3 7 2 62 82 18C 27.4 25.9 6 4 8 4 11 51 19C* 10 15.8 3 3 8 3 68 84 *The Example 19C composition was formulated and tested separately in Table 13a and 13B, so the data varies from Table 6B & 6D.

[0096] As shown in Table 13A, above, the inventive compositions of Examples 15 and 17 can be formulated at zero VOC to give shelf stable compositions which exhibit better coating gloss than any comparative (Examples 16C and 18C) that is zero VOC. As shown in Table 13B, above, the Inventive compositions exhibited better 1-day block resistance than any comparative Example and faster hardness development than the comparative SHE polymer of Example 19C. Even if the SHE polymer has phosphorus acid groups and, thus the ability to form pigment composites, the Example 19C control shows poor gloss development without independent encapsulation of opacifying pigments.

[0097] As shown in Tables 14 A and B, below, coating formulations of the present invention formulated as in

TABLE-US-00022 TABLE 14A Coating Performance MFFT (visual/ % VOC mechan- Example Formulation OPVC (g/L) ical) (° C.) 20 Polymer Encapsulated 18 0 <0/4.9 Opacifying Pigment 9 + Binder 1E 21 Polymer Encapsulated 18 0 <0/0.sup.  Opacifying Pigment 10 + Binder 1E 22 Polymer Encapsulated 18 0 1.4/3.6  Opacifying Pigment 9 + Hard polymer 2 23 Polymer Encapsulated 18 0 <0/4.7 Opacifying Pigment 10 + Hard polymer 2 24C TiO.sub.2 + polymer 2C + Binder 1E 18 0 0.4/4.5  25C TiO.sub.2 + polymer 3C + Binder 1E 18 0 <0/3.7 26C TiO.sub.2 + polymer 2C + Hard 18 0 <0/3.2 polymer 2 27C TiO.sub.2 + polymer 3C + Hard 18 0 <0/0.6 polymer 2

TABLE-US-00023 TABLE 14B Coating Performance König König Hard- Hard- RT Hot RT Hot ness ness block, block, block, Block 20° 60° Example 1 day 7 day 1 day 1 day 7 day 7 day Gloss Gloss 19C* 9.2 18.0 3 2 7 4 69 85 20 20.6 22.6 8 3 8 6 52 75 21 15.9 17.9 8 7 8 7 53 75 22 23.9 25.9 9 6 9 7 36 67 23 18.6 20.6 8 7 9 8 34 67 24C 25.3 28.6 8 7 8 7 14 51 25C 20 23.3 7 6 8 7 5 27 26C 25.9 27.9 9 3 10 4 3 21 27C 19.9 21.9 8 3 9 3 3 17 *The Example 19C composition was tested separately in Table 14B and so data varies from Tables 13A and 13B.

[0098] As shown in Tables 14A and 14B, above, the use of soft polymer encapsulated pigment and hard binder polymers enable coatings that can be formulated at zero VOC. Binder polymer 1B in Example 19C can absorb onto a TiO.sub.2 surface to form polymer opacifying pigment composites but exhibits poor 1 day hardness development and block resistance. The combinations of soft and hard polymers without polymer encapsulated pigments in Examples 24C, 25C, 26C and 27C showed acceptable 1-day block resistance and hardness development than the coating in Example 19C; however, the inventive polymer encapsulated pigment compositions exhibit far better gloss in a coating.