Latex composition with extender and silicone additive

Abstract

The present invention is a composition comprising an aqueous dispersion of a) polymer particles functionalized with structural units of a phosphorus acid monomer; b) one or more inorganic extenders; and c) polyorganosiloxane resin particles having a D50 particle size in the range of from 1 μm to 10 μm, and a number average molecular weight in the range of from 100,000 to 1,000,000 Daltons. The composition of the present invention is useful in a matte paint formulation that forms a coating with a balance of desirable coefficient of friction, mar resistance, and scratch resistance properties.

Description

[0001] Latex Composition with Extender and Silicone Additive

[0002] of the Invention

[0003] The present invention relates to a composition comprising an aqueous dispersion of polymer particles (a latex), one or more extenders, and a silicone additive.

[0004] Coatings with damage tolerance are in demand for high traffic areas such as hallways and stairwells to attenuate surface damage arising from inadvertent contact of items such as clothing, packages, and luggage. Matte coatings are desirable for their ability to obscure surface imperfections in a substrate. The control of gloss, which is critical in the design of these low sheen decorative paints, is accomplished with matting agents (also known as extenders or dulling agents), which are inorganic particles of calcium carbonate, silica, clay, talc, and the like. Matting agents lower the sheen by increasing the surface roughness of the fdm; unfortunately, traditional matting agents compromise the durability and performance of the resulting film. Therefore, matte coatings are not used in high traffic areas due to poor resistance properties. Higher sheen (satin) paints, which are often used in these high traffic areas, still require incorporation of inorganic extender particles such as nepheline syenite, diatomaceous earth, and calcium carbonate to control gloss to a desired finish; however, damaging is exacerbated by the presence of these inorganic extenders, even at the low demand required for satin paints.

[0005] Accordingly, it would be an advantage to design paint formulations containing traditional inorganic extenders to provide damage tolerance in a finally formulated paint.

[0006] Summary of the Invention

[0007] The present invention addresses a need in the art by providing a composition comprising an aqueous dispersion of a) polymer particles functionalized with structural units of a phosphorus acid monomer; b) one or more inorganic extenders; and c) polyorganosiloxane resin particles having a D50 particle size in the range of from 1 pm to 10 pm, and a number average molecular weight in the range of from 100,000 to 1,000,000 Daltons. The composition of the present invention is useful in a matte paint formulation that provides coating with improved damage tolerance.Detailed Description of the Invention

[0008] The present invention is a composition comprising an aqueous dispersion of a) polymer particles functionalized with structural units of a phosphorus acid monomer; b) one or more inorganic extenders; and c) polyorganosiloxane resin particles having a D50 particle size in the range of from 1 pm to 10 pm, and a number average molecular weight in the range of from 100,000 to 1,000,000 Daltons.

[0009] The aqueous dispersion of polymer particles (i.e, the latex) may be an acrylic, a styrene-acrylic, or a vinyl ester latex functionalized with structural units of a phosphorus acid monomer, with acrylic latexes being preferred. Phosphorus acid monomers are phosphonates and dihydrogen phosphate esters of an alcohol that contains or is substituted with a polymerizable vinyl or olefinic group. Preferred dihydrogen phosphate esters are phosphates of hydroxyalkyl methacrylates, including 2-phosphoethyl methacrylate and phosphopropyl methacrylates, with 2-phosphoethyl methacrylate (PEM) being especially preferred. The term “structural unit” refers to the remnant of the monomer after polymerization. A structural unit of PEM is illustrated:

[0010]

[0011] The concentration of structural units of the phosphorus acid monomer is typically in the range of from 0.1 or from 0.2 or from 0.5 weight percent, to 5 or to 3 or to 2 weight percent, based on the weight of the polymer particles. The z-average particle size of the polymer particles as measured by dynamic light scattering is typically in the range of from 80 nm or from 100 nm, to 500 nm or to 300 nm or to 250 nm.

[0012] Inorganic extenders include oxides, hydroxides, carbonates, silicates, and phosphates of one or more alkaline earth and transition metals such as calcium, magnesium, aluminum, and iron. The extenders typically have a refractive index in the range 1.4 to 1.9, and include talc, clay, mica, sericite, calcium carbonate (CaCCh), nepheline syenite, feldspar, wollastonite, kaolinite, dicalcium phosphate, and diatomaceous earth.

[0013] The polyorganosiloxane resin particles have a number average molecular weight (Mn) in the range of from 100,000 or from 200,000 Daltons, to 1,000,000 or to 700,000 or to500,000 Daltons, as measured by gel permeation chromatography, described hereinbelow. The polyorganosiloxane resin particles contain the following repeat units:

[0014]

[0015] where each R is independently phenyl or Ci-Ce alkyl, preferably methyl; and n is preferably from 1,200 or from 1,500 or from 2,000, to 10,000 or to 7,000 or to 5,000.

[0016] The Dso particle size of the polyorganosiloxane resin particles as determined by dynamic light scattering is in the range of from 1 pm or from 2 pm or from 3 pm, to 10 pm or to 7 pm or to 5 pm.

[0017] The composition of the present invention is preferably a matte paint composition that further comprises one or more rheology modifiers, an opacifying pigment such as TiCh, a surfactant, a dispersant, a defoamer, and optionally a coalescent. Based on the weight of the matte paint composition, a) the concentration of the polymer particles is typically in the range of from 8 or from 10 or from 12 weight percent, to 30 or to 25 or to 20 weight percent; b) the concentration of the one or more extenders in the paint composition is typically in the range of from 10 or from 15 weight percent, to 30 or to 25 weight percent; and c) the concentration of the polyorganosiloxane resin particles is preferably in the range of from 0.01 or from 0.02 or from 0.03 weight percent, to 1.0 or to 0.5 or to 0.2 weight percent.

[0018] Examples

[0019] Gel Permeation Chromatographic Measurement of Mnof Polyorganosiloxane Resin

[0020] Gel permeation Chromatography was carried out using a Waters 2695 Separations Module and a Waters 2410 differential refractometer. The separation was made with two (300 mm x 7.5 mm) Polymer Laboratories PLgel 5-pm Mixed-C columns (molecular weight separation range of 200 to 2,000,000), preceded by a PLgel 5-pm guard column (50 mm x 7.5 mm). The analyses were performed using certified grade THF flowing at 1.0 mL / min as the eluent, and the columns and detector were controlled at 35 °C. The samples were prepared in THF at a concentration of 10 mg / mL, then solvated for 1 h with occasional shaking, and filtered through 0.45-pm PTFE syringe filters prior to analysis. An injection volume of 100 pL was used and data was collectedfor 25 min. Data collection and analyses were performed using Thermo-Lab systems Atlas chromatography software and Polymer Laboratories Cirrus GPC software. Mn(alternatively, the degree of polymerization (n)) was determined relative to a calibration curve (3rd order) created using polystyrene standards covering the molecular weight range of 580 - 2,300,000.

[0021] Paint Formulations

[0022] Matte paint formulations were prepared using materials shown in Table 1. All values are in grams. Dispersant refers to TAMOL™ 165A Dispersant; KTPP refers to potassium

[0023] tri polyphosphate; Surfactant refers to TERGITOL™ 15-S-9 Surfactant; Defoamer refers to DOWSIL™ 107F Defoamer; TiO refers to Ti-Pure R-706 TiO2; Pigment 1 refers to Omyacarb 8 CaCOv Pigment 2 refers to Optiwhite Calcined Kaolin Clay; Binder 1 refers to EVOQUE™ 3150 Pre -composite (49 wt% solids), which is a blend of PEM -functionalized polymer particles with acorn morphology and latex particles with spherical morphology that are not functionalized with a phosphorus acid monomer; Binder 2 refers to RHOPLEX™ VSR- 1065 Acrylic Emulsion, which is a non-PEM functionalized binder; Coalescent refers to Texanol Ester Alcohol; Resin 1 refers to DOWSIL™ 5-7222 LF Emulsion (D50: 0.6 pm; Mn: 68,423 Daltons; 60 wt% solids); Resin 2 refers to DOWSIL™ 52 Dispersion (D50: 3.8 pm; Mn: 286,000 Daltons; 64 wt% solids); RM 1 refers to ACRYSOL™ RM-725 Rheology Modifier; and RM 2 refers to ACRYSOL™ RM-3030 Rheology Modifier. (TAMOL, TERGITOL, DOWSIL, EVOQUE, RHOPLEX, and ACRYSOL are all Trademarks of The Dow Chemical Company or its

[0024] Affiliates.)Table 1 -Matte Paint Formulations

[0025]

[0026] Paint drawdown method

[0027] Paints were drawn down to a coating thickness of 7 mil. All drawdowns were dried in a controlled temperature and humidity room at 23 °C and 50% relative humidity before testing. All coated samples were aged for 7 d before testing.Coefficient of Friction Measurement

[0028] Kinetic friction coefficients of paint drawdowns were measured using a high throughput research (HTR) tribometer using 3 / 8” stainless steel balls as friction probes. Balls were pressed against the paint drawdown and various normal loads (N) were applied (100 g, 200 g, 300 g) while balls were set to move at fixed speed of 2 mm / s. Two measurements were done for every applied force. The lateral force (f) needed to move the probe at constant speed is measured to compute the COF (p): ^=f / N. The lower the COF, the better.

[0029] Mar Resistance Measurement

[0030] Mar resistance describes the ability of a paint to resist damage caused by light abrasion. Mar resistance was measured in accordance with ASTM D5178, using a balanced beam tester with a U-shaped loop. A 500-g weight was placed on the cantilever of the apparatus, and the glass substrate coated with paint was pushed below the stylus. Paints were then visually inspected for mar, and given subjective mar ratings 1, 2 or 3 with 3 suggesting a minimal surface damage.

[0031] Scratch Resistance Measurement

[0032] Scratch resistance is the ability of a coating to resist film fracture from comparatively high shear forces. Scratch resistance tests were performed in accordance with ASTM D5178 using a balanced beam tester equipped with a U-shaped scraping / marring loop. A stylus was placed on the substrate angled at 45° to the surface, and a cantilever was loaded with weights. The glass substrate coated with paint was pushed below the stylus, and the coatings were visually inspected for scratch, which was defined by a complete film loss to the substrate. To test scratch resistance, a lower weight load was placed on the cantilever of the apparatus, and successively larger weights (in increments of 0.5 kg) were used until a scratch was visible. The critical scratch resistance (in kg) was recorded as the highest weight that mars the paints without leading to a scratch. Higher weights are indicative of improved scratch resistance.Table 2 illustrates, COF, mar resistance (Mar), and scratch resistance (Scratch) for coatings made from each formulation.

[0033] Table 2 - COF, Mar, and Scratch Resistance Data

[0034]

[0035] The results demonstrate a superior combination of COF, mar resistance, and scratch resistance for coatings prepared from compositions containing PEM-functionalized binder and high molecular weight large particle size polyorganosiloxane resin.

Claims

Claims:

1. A composition comprising an aqueous dispersion of a) polymer particles functionalized with structural units of a phosphorus acid monomer; b) one or more inorganic extenders; and c) polyorganosiloxane resin particles having a D50 particle size in the range of from 1 pm to 10 pm, and a number average molecular weight in the range of from 100,000 to 1,000,000 Daltons.

2. The composition of Claim 1 wherein the polymer particles functionalized with structural units of a phosphorus acid monomer have a z-average particle size in the range of from 80 nm to 500 nm; wherein the concentration of structural units of the phosphorus acid monomer is in the range of from 0.1 to 5 weight percent, based on the weight of the polymer particles.

3. The composition of Claim 2 wherein the structural units of the phosphorus acid monomer are structural units of 2-phosphoethyl methacrylate.

4. The composition of Claim 1 wherein the one or more inorganic extenders is an oxide, a hydroxide, a carbonate, a silicate, or a phosphate of one or more metals selected from the group consisting of calcium, magnesium, aluminum, and iron.

5. The composition of Claim 3 wherein the one or more extenders is selected from the group consisting of talc, clay, mica, sericite, CaCCh. nepheline syenite, feldspar, wollastonite, kaolinite, dicalcium phosphate, and diatomaceous earth.

6. The composition of Claim 1 wherein the number average molecular weight of the polyorganosiloxane resin particles is in the range of from 200,000 Daltons to 700,000 Daltons.

7. The composition of Claim 3 wherein the number average molecular weight of the polyorganosiloxane resin particles is in the range of from 200,000 Daltons to 500,000 Daltons; the D50 particle size of the polyorganosiloxane resin particles as determined by dynamic light scattering is in the range of from 2 pm to 5 pm; and the extender is clay or CaCCh or a combination thereof.

8. The composition of any of Claims 1 to 7 which further comprises one or more rheology modifiers, an opacifying pigment, a dispersant, a surfactant, and a defoamer; wherein, based on the weight of the composition, the concentration of polymer particles functionalized with structural units of the phosphorus acid monomer is in the range of from 10 to 25 weight percent, the concentration of the polyorganosiloxane resin particles is in the range of from 0.01 to 0.5weight percent, and the concentration of the one or more extenders is in the range of from 10 to 30 weight percent; wherein the composition is a matte paint composition.

9. The matte paint composition of Claim 8 wherein the opacifying pigment is TiCh; and wherein, based on the weight of the composition, the concentration of polymer particles functionalized with structural units of the phosphorus acid monomer is in the range of from 12 to 20 weight percent, the concentration of the polyorganosiloxane resin particles is in the range of from 0.03 to 0.2 weight percent, and the concentration of the one or more extenders is in the range of from 15 to 25 weight percent.

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