Waterborne coating composition

Abstract

A waterborne coating composition including: an aqueous emulsion polymer having a copolymerized Phosphorous-acid monomer, an aqueous dispersion of cement, and a solid inert filler, each in certain amounts, is provided. A method for providing a coated substrate employing the waterborne coating composition that has been subsequently activated and the coated substrate so formed are also provided.

Claims

1. A waterborne coating composition comprising: (a) an aqueous emulsion polymer, said emulsion polymer comprising, as copolymerized units from 0.1% to 10% Phosphorous-acid monomer, based on the dry weight of said emulsion polymer; said emulsion polymer in an amount of from 8% to 30% by weight on a dry basis; (b) an aqueous dispersion of cement, said aqueous dispersion having a cement solids content of from 50% to 80% by weight, said cement selected from the group consisting of aluminous cement, sulfoaluminous cement, and mixtures thereof, said cement in an amount of from 10% to 30% by weight on a dry basis; and (c) solid inert filler in an amount of from 40% to 82% by weight on a dry basis; wherein said emulsion polymer/said cement ratio is from 0.66 to 1.5 on a dry/dry basis; and wherein the water/said cement ratio is from 0.6 to 2.0 on a dry cement basis.

2. The waterborne coating composition of claim 1 wherein said emulsion polymer comprises, as copolymerized units from 1% to 5% Phosphorous-acid monomer, based on the dry weight of said aqueous emulsion polymer.

3. The waterborne coating composition of claim 1 wherein said emulsion polymer is in an amount of from 10-17% by weight on a dry basis; wherein said aqueous dispersion of cement is in an amount of from 10% to 20% by weight on a dry basis; and wherein solid filler is in an amount of from 63% to 80% by weight on a dry basis.

4. The waterborne coating composition of claim 1 wherein said emulsion polymer/said cement ratio if from 0.7 to 1.25 on a dry/dry basis.

5. A method for providing a coated substrate comprising: (a) providing a solid substrate surface; (b) applying thereon an activated waterborne composition comprising (i) a waterborne coating composition comprising (aa) an aqueous emulsion polymer, said emulsion polymer comprising, as copolymerized units from 0.1% to 10% Phosphorous-acid monomer, based on the dry weight of said emulsion polymer; said emulsion polymer in an amount of from 8% to 30% by weight on a dry basis; (bb) an aqueous dispersion of cement, said aqueous dispersion having a cement solids content of from 50% to 80% by weight, said cement selected from the group consisting of aluminous cement, sulfoaluminous cement, and mixtures thereof, said cement in an amount of from 10% to 30% by weight on a dry basis; and (cc) solid inert filler in an amount of from 40% to 82% by weight on a dry basis; wherein said emulsion polymer/said cement ratio is from 0.66 to 1.5 on a dry/dry basis; and wherein water/said cement ratio is from 0.6 to 2.0 on a dry cement basis; wherein the pH of said waterborne coating composition has been adjusted to a pH>11; and (ii) an aqueous activator solution comprising from 0.4% to 0.8% of a metal salt selected from the group consisting of sodium, potassium, magnesium and calcium salts, by weight of metal based on dry weight of said cement; and (d) drying said activated waterborne coating composition.

6. The method for providing a coated substrate of claim 5 wherein said emulsion polymer comprises, as copolymerized units from 1% to 5% Phosphorous-acid monomer, based on the dry weight of said aqueous emulsion polymer.

7. The method for providing a coated substrate of claim 5 wherein said emulsion polymer is in an amount of from 10% to 17% by weight on a dry basis; wherein said aqueous dispersion of cement is in an amount of from 10% to 20% by weight on a dry basis; and wherein solid filler is in an amount of from 63% to 80% by weight on a dry basis.

8. The method for providing a coated substrate of claim 5 wherein said emulsion polymer/said cement ratio is from 0.7 to 1.25 on a dry/dry basis.

9. A coated substrate formed by the method of claim 5.

Description

EXAMPLE 1. FORMATION OF WATERBORNE COATING COMPOSITION AND ACTIVATED WATERBORNE COATING COMPOSITION

(1) Blending procedure: An aqueous emulsion polymer (at 51% solids) and an aqueous dispersion of cement were mixed before addition of an antifoam agent followed by sand fillers in the amounts presented in Table 1.1. The paint formulation was stable and may be stored for over a month. The activator solution was premixed according to the mass ratios in Table 1.1 and added while stirring. The activated waterborne coating composition was then applied to paper strips at a thickness of 2 mm and dried for seven days before Taber abrasion tests.

(2) TABLE-US-00002 TABLE 1.1 Compositions of waterborne coating composition and activator solution Paint Emulsion polymer (51% solids) 20.8% EXALT (60% solid) 17.2% SIBELCO C 300 20.6% SIFRACO NE 03 41.3% FOAMASTER MO2134 0.1% 100% Activator PERAMIN AXL-80 0.70% NaOH (50%) 1.75% H.sub.2O 0.35%

(3) EXALT and PERAMIN are trademarks of Kerneos, SA; SIBELCO is a trademark of Sibelco N.V.; SIFRACO is a trademark of Sifraco, SA; FOAMASTER is a trademark of BASF SE.

EXAMPLE 2. EVALUATION OF MECHANICAL PROPERTIES

(4) Mechanical properties related to durability performance were measured by abrasion results on coatings formed by the method of the present invention according to Example 1. Dried/hardened coatings were subjected to abrasion tests.

(5) TABLE-US-00003 TABLE 2.1 Evaluation of abrasion resistance Polymer type Abrasion/g Control solventborne 1.39 0.13 Example 2.A1 waterborne 0.08 0.03 Example 2.A2 waterborne 0.15 0.03 Comp. Ex. 2.B1 waterborne 0.27 0.03 Comp. Ex. 2.B2 waterborne 0.29 0.04

(6) The dry coated substrates of the invention Examples 2.A1 and 2.A2 incorporating aqueous emulsion polymers A1 and A2, respectively, exhibit a statistically significant advantage in abrasion resistance relative to that of the comparative examples including aqueous emulsion copolymers, B1 and B2 not including Phosphorous acid monomer.

EXAMPLE 3. EVALUATION OF COMPATIBILITY OF AQUEOUS EMULSION POLYMERS WITH ACTIVATOR SOLUTIONS

(7) An EXALT compatible emulsion is desirably stable at pH>13 and at high ionic strength. The compatibility tests were performed as follows. For each emulsion the pH was raised above 13 using NaOH (50%). In a separate vial the accelerator salt (PERAMIN AXL-80; Li2SO4.H2O) was mixed with the aqueous emulsion polymer at a level of 7 wt % based on emulsion polymer solids.

(8) The data in Table 3.1 presents the amount of salt that can be added before the emulsions flocculate.

(9) TABLE-US-00004 TABLE 3.1 Robustness of different aqueous emulsion polymers against cement activation conditions of high ionic strength. Emulsion Polymer B3 B1 A1 A3 Amount of Li.sub.2SO.sub.4H.sub.2O 2.5% 2.8% 30% 10% (PERAMIN AXL-80) added before flocculation wt %, (10 g emulsion)

(10) Aqueous emulsion polymers A1 and A3 including copolymerized Phosphorous-acid monomer exhibit a surprising advantageous stability under these activation conditions and, in particular resistance to high salt contents relative to that of the comparative aqueous emulsion polymers not including Phosphorous-acid monomer, B1 and B3.

EXAMPLE 4. FORMATION OF WATERBORNE COATING COMPOSITION AND ACTIVATED WATERBORNE COATING COMPOSITION SUITABLE FOR USE AS A TRAFFIC OR ROAD-MARKING PAINT

(11) Waterborne coating compositions were prepared according to Table 4.1. To activate the waterborne coating compositions the activator solution was mixed manually with the coating composition shortly before applying the coating. All other manipulations were carried out as described in ASTM norm D 711-89.

(12) TABLE-US-00005 TABLE 4.1 Composition of waterborne coating compositions and activator solution Example Comp. 4.3 Comp. 4.2 4.1 (Compositions in g) Emulsion Polymer A1 112 Emulsion Polymer B1 103 101 Emulsion Polymer B2 25 25 EXALT (wt % solids) 133 (65) 103 (60) 124(70) SIBELCO C 300 108 111 108 SIFRACO NE03 184 226 184 FOAMASTER MO 2134 0.5 0.5 0.5 Activator-Accelerator PERAMIN AXL-80 6.1 4.3 6.1 NaOH (50%) 15.1 10.8 15.1 Water 3 2.2 3

EXAMPLE 5. EVALUATION OF DRYING PERFORMANCE OF ACTIVATED WATERBORNE COATING COMPOSITIONS

(13) TABLE-US-00006 TABLE 5.1 Drying properties of activated waterborne compositions Waterborne Coating Composition 4.1 Comp.4.2 Comp.4.3 No Pick-up Time (50% rel. humidity): Film thickness (mm) 2 2 No adherence to rubber rings 35-45 50 (min) No marks on paint (min) 60 50 No Pick-up Time (90% rel. humidity): Film thickness (mm) 2 2 2 No adherence to rubber rings 30 >150 210 (min) No marks on paint (min) 70 >150 >240

(14) At 50% RH the activated waterborne coating composition (4.1) of the invention and the comparative composition (4.2) performed similarly. However, at 90% RH surprisingly the setting performance of the activated waterborne coating composition (4.1) was not notably affected by the humidity level. In comparison the setting times of the comparative compositions (4.2 and 4.3) were much longer at higher humidity.

EXAMPLE 6

(15) Mechanical properties related to durability performance were measured by abrasion results on coatings formed by the method of the present invention according to Example 4. Dried/hardened coatings were subjected to Taber abrasion as per the Test Method abrasion tests.

(16) TABLE-US-00007 TABLE 6.1 Evaluation of abrasion resistance Polymer type Composition Abrasion/g Control solventborne MMA 1.59 Example 6.1 waterborne A1/B2 75/25 0.45 Comp. Ex. 6.2 waterborne B4 1.56

(17) A dry coating of the invention (Ex. 6.1) exhibited strikingly superior Taber abrasion results when compared to a dry coating (comp. Ex. 6.2) based on a styrene/acrylic emulsion polymer not containing copolymerized Phosphorous acid monomer.

EXAMPLE 7. EVALUATION OF DRYING PERFORMANCE OF ACTIVATED WATERBORNE COATING COMPOSITIONS

(18) TABLE-US-00008 TABLE 7.1 Drying time performance of coatings formed by the method of the present invention according to Example 4. 7.1 Waterborne Coating A1/B2, Comp.7.2 Composition 75/25, wt. B4 No Pick-up Time (50% rel. humidity): Film thickness (mm) 2 2 No marks on paint (min) 65 170 No Pick-up Time (90% rel, humidity): Film thickness (mm) 2 2 No marks on paint (min) 65 >250

(19) Surprisingly, the setting performance of the activated waterborne coating composition of the invention (7.1) was not notably affected by the humidity level. The setting time of the comparative composition (7.2) was much longer at 90% RH.