WO2025096108A1

WO2025096108A1 - Quick drying coating composition

Info

Publication number: WO2025096108A1
Application number: PCT/US2024/049358
Authority: WO
Inventors: Kayla GENTILE; Michael W. Leonard; Katherine ELBERT
Original assignee: Rohm and Haas Co
Current assignee: Rohm and Haas Co
Priority date: 2023-10-30
Filing date: 2024-10-01
Publication date: 2025-05-08
Anticipated expiration: 2026-04-30

Abstract

Quick drying coating formulations that contain high levels of filler and high viscosity suitable for EIFS application can be made using a binder that contains opacifying acrylic polymer.

Description

QUICK DRYING COATING COMPOSITION

FIELD

This invention relates to the field of architectural coating compositions.

INTRODUCTION

High-viscosity coating compositions are frequently used as the finish coating on an exterior insulation and finish system (EIFS) cladding for a building, although they can be used on other substrates as well.

EIFS are used on the outside of buildings to provide good thermal insulation, weather bility and appearance at a low price. EIFS comprise at least three layers:

1. A layer of insulation, which is typically foam insulation board such as STYROFOAM™ insulation, adhered directly or indirectly to a wall substrate by adhesive or mechanical fasteners;

2. A layer of base coat adhered directly or indirectly to the insulation layer, which comprises a fiber mesh embedded in a coating material; and

3. A layer of finish coat adhered directly or indirectly to the base coat, which comprises a coating material that provides we therability and the desired appearance.

Other layers may also be included, such as a water channel under the insulation layer to let water escape if it gets under the EIFS or a waterproof layer to protect the substrate from water that gets under the EIFS. EIFS and layers found in them are described in many public references such as US Patent Publications 2014/0373474 and 2015/0159008 and “Application Fast Facts: EIFS”, Publication 832-00189-01 published by The Dow Chemical Company and available at dow.com/en-us/market/mkt-building- construction/sub-build-wall-systems-insulation-facade.html.

The finish coat generally contains inorganic filler, an organic binder and additives. The filler typically includes sand and other inorganic particulates; it may include some materials that are classified as inorganic pigments, such as titanium dioxide. The binder is frequently an emulsion polymer, such as an acrylic polymer. In many cases, the finish coat is designed to have high solar reflectance, in order to minimize solar heating of the underlying building and reduce energy and cost needed to keep the building cool. In these cases, the fillers may contain a high content of white ingredients, such as titanium dioxide and calcium carbonate. Other additives may include known additives for exterior coatings such as organic pigments, thickeners and flow modifiers, surfactants, antioxidants and stabilizers.

The finish coat is frequently applied as an aqueous slurry. The slurry generally has high solids and high viscosity, so that the finish coat can be applied with a trowel on a vertical surface at a thickness of 0.1 cm to 2.5 cm. The external appearance is often similar to stucco, so that EIFS surfaces are sometimes referred to as “synthetic stucco.”

Drying time is a concern for all architectural coatings, including the finish coat on EIFS. The coatings are applied outdoors and can be damaged if they are hit by rain or inadvertent sprays of water before they are dry. Users often want architectural coating to dry quickly after it is applied, in order to minimize the risk of water damage. Drying time is especially a concern for EIFS finish coats, because EIFS finish coats are thicker than ordinary coats of paint, and so they take longer to dry.

It is known to speed drying time of aqueous coating compositions by adding organic polyamine and ammonia to the coating composition. See for example US Patent 5,527,853. However, the formulation produces an ammonia odor as it dries, and the resulting coating may be susceptible to yellowing.

It is desired to produce high solids coating compositions that dry quickly to resist water, without the need for organic polyamines.

SUMMARY

One aspect of the present invention is a coating composition that contains: a) inorganic filler; b) a film-forming opacifying acrylic polymer (OAP) binder that comprises hollow sphere particles and is present in a concentration effective to bind the filler and other solid components of the coating composition to a substrate; and c) water in a quantity sufficient to fully wet the dry ingredients and provide a slurry, wherein the combined pigment volume concentration (PVC) of inorganic filler and hollow sphere particles in the coating composition is at least 65 and the coating composition has a viscosity of at least 100 g as measured using a Krebs Stormer Model KU-1 with a paste spindle.

A second aspect of this invention is a process to coat an architectural substrate comprising the steps of: a) applying the coating composition in the first aspect of this invention directly or indirectly to the architectural substrate; and b) permitting the coating composition to dry.

A third aspect of this invention is a coated architectural substrate comprising (1) an architectural substrate and (2) a dry coating adhered directly or indirectly to the architectural substrate, wherein : a) the dry coating comprises inorganic fdler and a film-forming opacifying acrylic polymer (OAP) binder that comprises hollow sphere particles and is present in a concentration effective to bind the filler and other components of the dry coating to a substrate; and b) the combined pigment volume concentration (PVC) of inorganic filler and hollow sphere particles in the dry coating is at least 65 ; and c) the dry coating is at least 0.05 cm thick.

In the high-solids coating compositions of this invention, the OAP binders provide rapid drying without the need for an organic polyamine drying agent. DETAILED DESCRIPTION

The invention is a high-PVC coating composition that contains filler, binder and water. The binder contains film-forming opacifying acrylic polymer (GAP). The composition is particularly useful as a finish layer in an EIFS cladding.

Filler

The fillers used in the coating composition are powders and granules that are insoluble in water. Suitable fillers are known in the coating industry and are commercially available. See for example Gysau, Fillers for Paints (3^rd Ed.), published by Vincenz Network GmbH (2017); and “Functional Silicate Fillers: Basic Principles”, Painting & Coatings Industry (August 1, 2002) (https://www.pcimag.com/articles/84909-functional-silicate-fillers-basic-principles).

In some embodiments, the fillers are inorganic. In some embodiments, the inorganic fillers contain oxides, carbonates and sulfates of silicon, calcium, titanium and/or aluminum. Examples of common inorganic fillers include silica, titanium dioxide, calcium carbonate, dolomite, kaolin, barium sulfate, wollastonite, mica, talc, feldspar and glass particles.

In some embodiments, the filler contains materials that are classified as inorganic pigments or pigment extenders. Examples of light colored inorganic pigments and pigment extenders that may be in the filler include titanium dioxide, antimony white, titanium white, zinc white or barium sulfate, chrome yellow, cobalt yellow and titanium yellow. The filler may also contain dark colored inorganic pigments, such as iron and copper oxides and carbon black.

It is known in the coating and EIFS art to select fillers that have a particle size suitable for the coating composition. Some examples of coarse fillers may have an average particle size of at least 100 microns or at least 200 microns or at least 300 microns or at least 500 microns and may have an average particle size of at most 3 mm or at most 2 mm or at most 1.5 mm or at most 1 mm or at most 800 microns or at most 600 microns. Some examples of fine fillers and pigment extenders may have smaller particle sizes, such as an average particle size of at least 1 micron and at most 100 microns.

The fillers are typically insoluble in water. Dispersing and wetting agents may help to maintain a stable slurry or dispersion of the filler in water. Suitable dispersing and wetting agents are known and commercially available, such as under the following trademarks: TAMOL™, Calgon, and Dispex. In some embodiments, the dispersant is a polycarboxylate, a polyphosphate or a block copolymer having blocks that interact with water and blocks that interact with the filler/pigment. In some embodiments, a wetting agent is a surfactant such as a salt of a fatty acid, a poly (ethylene oxide) surfactant or a silicone- based surfactant.

The quantity of fillers in coatings formulations can be described using pigment volume concentration (“PVC”), which is the volume of pigment and filler as a percent of the total volume of solid components in the coating formulation. PVC is calculated by Formula 1 :

wherein V_p is the dry volume of pigment, V_e is the dry volume of filler and Vb dry is the dry volume of binder. In this document, hollow sphere particles in the binder are included as part of the pigment in “p”.

Coating compositions of this invention have a PVC of at least 65. In some embodiments, the PVC of the coating composition is at least 70 or at least 71 or at least 73 or at least 75 or at least 77 or at least 79 or 80. In some embodiments, the PVC of the coating composition is at most 90 or at most 88 or at most 86 or at most 84 or at most 82. For example, the PVC of the coating composition may be from 71 to 90 or from 73 to 88 or from 75 to 86 or from 77 to 84.

In some embodiments, the hollow sphere particles in the binder supply at least 20 percent of the PVC or at least 25 percent or at least 30 percent or at least 35 percent. In some embodiments, the hollow sphere particles in the binder supply at most 50 percent of the PVC or at most 45 percent or at most 40 percent.

The quantity of filler may also be described in terms of weight percent. In some embodiments, the coating composition contains at least 70 weight percent filler, based on the weight of dry ingredients excluding water, or at least 75 weight percent or at least 80 weight percent or at least 82 weight percent or at least 84 weight percent. (The “dry ingredients” are the inorganic filler, the binder and other solid additives to the coating composition. The weight of dry ingredients is the dry weight of the dry ingredients.) In some embodiments, the coating composition contains at most 94 weight percent filler, based on the weight of dry ingredients excluding water, or at most 93 weight percent or at most 92 weight percent or at most 91 weight percent or at most 90 weight percent. For example, the coating composition may contain from 75 to 93 weight percent filler, based on dry ingredients excluding water, or from 80 to 92 weight percent or from 84 to 90 weight percent.

In some embodiments, the coating composition contains at least 50 weight percent filler, based on all ingredients including water, or at least 60 weight percent or at least 64 weight percent or at least 67 weight percent. In some embodiments, the coating composition contains at most 85 weight percent filler, based on all ingredients including water, or most 80 weight percent or at most 78 weight percent or at most 76 weight percent. For example, the coating composition may contain from 50 to 85 weight percent filler, based on all ingredients including water, or from 60 to 70 weight percent or from 64 to 78 weight percent or from 67 to 76 weight percent.

Binder

The coating composition contains an OAP binder. An OAP binder comprises both (1) shells of rigid high-Tg polymer that enclose void spaces (“hollow sphere particles”); and (2) film forming low-Tg polymer that surrounds the shells of rigid high-Tg polymer. OAP binders and processes to make them are known and reported in references such as US Patents US 6,020,435, US 7,939,572 B2 and US 7,629,414 B2, and US Patent Publications US 2010/0010118A1 and US 2008/0171810 Al. They can be made in a multistep emulsion polymerization.

• First, a high-Tg shell is polymerized on an acidic polymer core in an aqueous emulsion.

• Second, a low-Tg film-forming polymer is polymerized on the high-Tg shell. Monomers used to make the film-forming polymer are selected to plasticize the high-Tg shell.

• Third, a base in the aqueous emulsion reacts with the acidic polymer core, drawing water inside the plasticized high-Tg shell and expanding the plasticized shell to create a water-filled void.

• Fourth, the monomers that plasticize the high-Tg shell are further polymerized, such that the high-Tg shell is no longer plasticized but is rigid.

When the OAP binder dries, water migrates out of the void space to leave a void encapsulated by the high-Tg shell.

The OAP binders contain shells of rigid high-Tg polymer that enclose voids. In some embodiments, such as when the OAP binder is suspended in an emulsion, the voids may contain water in addition to residue of the acid polymer core. In some embodiments, such as when the OAP binder is dry, the voids may contain air in addition to residue of the acid polymer core.

In some embodiments, the high-Tg polymer has a glass transition temperature of at least 55°C or at least 60°C or at least 70°C or at least 80°C. There is no maximum desired glass transition temperature, but glass transition temperature above 150°C or 120°C or 105°C is rarely necessary.

Examples of suitable high-Tg polymers that can be used in the shell include polystyrene, styrene - acrylic copolymers, and acrylic polymers.

In some embodiments, the high-Tg polymer contains a polystyrene polymer, which may be a homopolymer or a copolymer. In some embodiments the polystyrene polymer contains at least 80 weight percent units derived from styrene monomer or at least 85 weight percent or at least 90 weight percent. In some embodiments, the polystyrene polymer contains up to 100 weight percent units derived from styrene monomer. Comonomers for polystyrene copolymers are known, and common examples include but are not limited to vinyl toluene, acrylonitrile and methyl methacrylate. Emulsion polymerization of polystyrene is known and described in publications such as; US3914338A, US4427836A, US4469825A, US4594363A, US7939572B2, US20010009929A1, and Ramli, “Hollow Polymer Particles: a Review” RSC Adv., 2017, 7, 52632. (published at https://pubs.rsc.org/cn/contcnt/articlcpdf/2017/ra/c7ral0358a)

In some embodiments, the high-Tg polymer contains an acrylic polymer. An acrylic polymer is a homopolymer or copolymer that contains repeating units derived from acrylic monomers. Acrylic monomers include acrylic acid, methacrylic acid and their esters. Exemplary esters used in acrylic monomers include alkyl esters such as alkyl groups containing from 1 to 8 carbon atoms or from 1 to 4 carbon atoms or in some cases methyl groups or ethyl groups. Particularly useful acrylic monomers are acrylic acid, methacrylic acid, acrylonitrile, butyl acrylate, 2 ethylhexyl acrylate, methyl acrylate, ethyl acrylate, methyl methacrylate and ethyl methacrylate. Exemplary acrylic polymers may contain at least 70 weight percent repeating units derived from acrylic monomers, or at least 80 weight percent or at least 90 weight percent or at least 95 weight percent. Exemplary acrylic polymers may contain up to 100 percent repeating units derived from acrylic monomers. Some exemplary acrylic polymers are copolymers containing units derived from two or more acrylic monomers, such as copolymers of butyl acrylate with methyl methacrylate and/or methacrylic acid. Some exemplary acrylic polymers may further contain repeating units derived from non-acrylic ethylenically unsaturated comonomers, such as styrene, vinyl acetate and similar vinyl esters, and crosslinking monomer such as divinylbenzene. The selection of monomers is known to influence the Tg of the resulting acrylic polymers. Increasing content of certain monomers such as methyl methacrylate and acrylonitrile and styrene is known to increase Tg of the resulting polymer, and increasing content of other monomers such as butyl acrylate is known to reduce Tg of the resulting polymer.

Emulsion polymerization of acrylic monomers is well-known. See e.g., US Patent 7,629,414 B2 and Emulsion Polymerization of Acrylic Monomers, published by Rohm & Haas Company (1966).

The OAP binder further contains film forming low-Tg polymer that surrounds the shells of rigid high-Tg polymer.

The concept of “film-forming” polymers is well understood. “Film-forming” means that a substance is capable of forming a film upon application to a solid surface. The ability of polymers and their solutions or emulsions to be film-forming is known and described in publications such as: P.A. Steward et aL, “An Overview of Polymer Latex Film Formation and Properties”, 86 Advances in Colloid and Interface Science at 195-267 (2000) and J. Guerts et aL, “New Waterborne Acrylic Binders for Zero VOC Paints”, 5 J. Coating TechnoL Res. at 57-63 (2008). Film forming polymer latexes generally contain suspended particles that can coalesce as they dry. Coalescence can arise from individual particles compacting, deforming, adhering to each other and/or having polymer chains diffuse with each other. Commonly, the film-forming ability of polymers increases with lower molecular weight and/or lower Tg and decreases with higher molecular weight and/or higher Tg.

In some embodiments, the low-Tg polymer has a glass transition temperature of at most 50°C or at most 45°C or at most 40°C or at most 30°C or at most 20°C or at most 10°C. There is no minimum desirable Tg, but Tg below -50 °C or -30 °C or -15 °C or 0°C or are seldom necessary.

In some embodiments, the low-Tg polymer contains an acrylic polymer, as already described, in which monomers are selected to yield a low-Tg film-forming polymer. In some embodiments, the low- Tg polymer contains at least 7 weight percent units derived from methyl methacrylate or at least 10 weight percent or at least 12 weight percent. In some embodiments, the low-Tg polymer contains at most 50 weight percent units derived from methyl methacrylate or at most 45 weight percent or at most 40 weight percent or at most 35 weight percent or at most 30 weight percent or at most 25 weight percent. In some embodiments, the low-Tg polymer contains at least 40 weight percent units derived from butyl acrylate or at least 50 weight percent or at least 60 weight percent or at least 65 weight percent or at least 65 weight percent or at least 65 weight percent. In some embodiments, the low-Tg polymer contains at most 93 weight percent units derived from butyl acrylate or at most 90 weight percent or at most 86 weight percent or at most 84 weight percent or at most 82 weight percent or at most 80 weight percent.

In some embodiments, the low-Tg acrylic polymer may contain cross-linking monomers. Examples of cross-linking monomers include but are not limited to acetoacetoxy ethyl methacrylate (AAEM), diacetoneacrylamide (DAAM, which may be crosslinked with adipic acid dihydrazide), and glycidyl methacrylate and other epoxies, which may be crosslinked in the presence of an amine functional group. The quantity of cross-linking should be kept low enough that the resulting polymer is still film forming. In some embodiments, the acrylic polymer contains no more than 10 weight percent cross-linking monomer, or no more than 6 weight percent or no more than 4 weight percent or no more than 2 weight percent. In some embodiments, the acrylic polymer contains 0 weight percent crosslinking monomer or at least 0.5 weight percent or at least 1 weight percent.

It may also be useful for the low-Tg polymer remain non-molten in temperatures that exterior coatings are commonly exposed to. In some embodiments, the low-Tg polymer has a melting temperature of at least 60°C or at least 75°C or at least 80°C or at least 95°C or at least 110°C. There is no maximum desirable melting temperature, but temperatures above 200°C arc seldom necessary.

In some embodiments, the low-Tg polymer makes up at least 50 weight percent of the dry ingredients in the OAP binder, excluding water, or at least 60 weight percent or at least 65 weight percent. In some embodiments, the low-Tg polymer makes up at most 90 weight percent of the dry ingredients in the OAP binder, excluding water, or at most 80 weight percent or at most 75 weight percent or at most 70 weight percent.

In some embodiments, the OAP binder is the only binder in the coating composition. In some embodiments, the binder of the coating composition contains a blend of the OAP binder and another binder polymer. Other binders are known and commercially available. They are described in publications such as “Paints” published by Department of Chemistry, University of York at https://www.essentialchemicalindustry.org/materials-and-applications/paints.html (March 18, 2013). Examples of other binders include certain acrylic polymers, polyurethane polymers, styrene-acrylic polymers and vinyl-acrylic polymers. Examples of binders that are commercially available include acrylic polymers and polymer dispersions available from the Dow Chemical Company under the RHOPLEX™, PRIMAL™, PARALOID™, and MAINCOTE™ trademarks.

In some embodiments, the OAP binder makes up at least 20 weight percent of the binder or at least 40 or at least 60 or at least 80. In some embodiments, the OAP binder makes up 100 percent of the binder.

In some embodiments, the binder makes up at least 5 weight percent of the dry ingredients in the coating composition, or at least 7 weight percent or at least 8 weight percent or at least 9 weight percent or at least 10 weight percent. In some embodiments, the binder makes up at most 25 weight percent of the dry ingredients in the coating composition, or at most 20 weight percent or at most 18 weight percent or at most 16 weight percent. For example, the binder may make up from 5 to 25 weight percent of the dry ingredients, or from 8 to 20 weight percent or from 10 to 16 weight percent.

In some embodiments, the binder makes up at least 4 weight percent of the total coating composition including water, or at least 5 weight percent or at least 6 weight percent or at least 7 weight percent or at least 8 weight percent. In some embodiments, the binder makes up at most 20 weight percent of the total coating composition including water, or at most 18 weight percent or at most 16 weight percent or at most 14 weight percent. For example, the binder may make up from 5 to 20 weight percent of the total coating composition, or from 7 to 18 weight percent or from 8 to 14 weight percent.

Other Additives

The coating composition may optionally contain other additives that are appropriate for finish coatings in EIFS, in addition to the filler, binder and water. Commercial embodiments of EIFS finish coatings typically contain multiple additives. Many such components are described in the publication Johan Bieleman (ed.), Additives for Coatings, published by WILEY-VCH Verlag GmbH (2000). Some examples of common additives are listed below. All of the additives listed below are commercially available with recommendations for their use.

The coating composition may optionally contain organic dyes and pigments in a quantity effective to color the resulting coating. Examples of suitable organic dyes and pigments include phthalocyanines (blue/green), quinacridones (red/yellow), quinone derivatives, and azo compounds.

The coating composition may optionally contain thickeners to make it easier to handle and apply. Examples of thickeners include inorganic materials, such as certain clays, and polymer thickeners, such as cellulose ethers, starches, and acrylic polymers.

The coating composition may optionally contain surfactants for a number of purposes. Some surfactants are emulsifiers, wetting agents, and dispersants, which help insoluble components to enter and remain in an emulsion or dispersion in the aqueous solvent. Some surfactants are antifoaming agents. Some surfactants can promote adhesion of the coating composition to a substrate.

The coating composition may optionally contain hydrophobic additives to improve the ability of the resulting coating to resist water infiltration. Examples of hydrophobic components may include waxes and polymers, such as polypropylene, as well as silicones, silanes, or siloxane components.

The coating composition may optionally contain levelling and coalescing agents. Examples of levelling additives include certain polyacrylate polymers, which have a low glass-transition temperature, such as 20°C or lower. Coalescing agents promote interaction of binder molecules as the coating dries on the substrate, to form a solid homogeneous film that does not redissolve when subjected to new water. Examples of coalescing agents include:

• certain branched and cyclic paraffins,

• certain esters such as 3-hydroxy-2,2,4-trimethylpentyl isobutyrate (TPiB), diesters of adipic acid (ADE), dimethyl phthalate (DMP), 2-hydroxypropyl ethylhexanoate (HPE), and benzyl benzoate, and • certain ether alcohols, such as ethylene glycol butyl ether, propylene glycol butyl ether, dipropylene glycol butyl ether (DPB), and propylene and ethylene glycol phenyl ether (PPH and EPH

The coating composition may optionally contain antioxidants. Antioxidants may contain a primary antioxidant, such as certain amines or sterically hindered phenols and/or a secondary antioxidant, such as certain organophosphates or thioesters.

The coating composition may optionally contain light and ultraviolet (UV) stabilizers. Examples of light and ultraviolet light (UV) stabilizers may include:

• UV absorbers such as benzotriazoles and other compounds having coordinated double bonds; and

• Sterically hindered amines such as compounds containing a 2,2,6,6-tetramethylpiperidine group.

The coating composition may optionally contain other additives to improve the dirt pickup resistance (DPUR) of the resulting coating. Examples of DPUR additives include some aromatic compounds, such as benzophenone and methyl-2- benzoyl benzoate, some fluorinated surfactants, some waxes, and some silicones, such as polydimethylsiloxane (PDMS).

In some embodiments, the quantity of additives is no more than 8 weight percent of the coating composition, based on dry ingredients excluding water, or no more than 6 weight percent or no more than 5 weight percent or no more than 4 weight percent or no more than 3 weight percent. The quantity of additives may be 0 weight percent, but in some embodiments, the quantity of other additives is at least 0.2 weight percent, based on dry ingredients excluding water, or at least 0.5 weight percent or at least 0.8 weight percent or at least 1 weight percent or at least 1.5 weight percent or at least 2 weight percent. In some embodiments, the quantity of additives is low enough that volume percent, weight percent excluding water, and weight percent including water are roughly the same, so the concentrations previously described can also apply weight percent including water. For example, in some embodiments, the coating composition contains from 0.2 to 8 weight percent additives, based on the dry weight of ingredients and excluding water, or from 0.5 to 5 weight percent or from 1 to 3 weight percent. In some embodiments, the coating composition contains from 0.2 to 8 weight percent additives, based on all ingredients including water, or from 0.5 to 5 weight percent or from 1 to 3 weight percent.

The coating compositions of this invention are quick drying without the need for an organic polyamine, but can dry even faster if they include an organic polyamine and a volatile amine. Suitable organic polyamines and volatile amines and their use in quick-drying formulations are described in US Patent Application 2008/0171810 Al and in US Patent 5,804,627. The organic polyamine is a polymer that contains from 20 to 100 weight percent repeating units that have a pendant amine group. In some embodiments, the polyamine has a weight average molecular weight of at least 1000 Da. Examples of volatile amines include ammonia, morpholine, lower alkyl amines, 2-dimethyl aminoethanol and ethylene diamine.

In some embodiments, faster drying from organic polyamines is not desired. In some embodiments, the coating composition contains less than 0.1 weight percent organic polyamine, based on dry ingredients excluding water, or no more than 0.08 wright percent or no more than 0.05 weight percent or no more than 0.01 weight percent. In some embodiments, the coating composition contains no measurable quantity (0 weight percent) organic polyamine.

In some embodiments, faster drying from organic polyamines is desired. In some embodiments, the coating composition contains at least 0.1 weight percent organic polyamine, based on dry ingredients excluding water, or at least 0.2 weight percent or at least 0.5 weight percent. In some embodiments, the coating composition contains no more than 10 weight percent organic polyamine, based on dry ingredients excluding water, or no more than 5 wright percent or no more than 2 weight percent.

Water

The coating composition contains water. The amount of water is suitable to fully wet the dry ingredients and to form a slurry.

In this invention, the slurry has a viscosity low enough that it can be applied smoothly and high enough that it can be applied in a thick layer to a vertical surface and dry without materially flowing down the surface. In EIFS, the slurry is typically applied with a trowel, unlike sprays and brushes typically used to apply paints. The coating composition has a viscosity of at least 100 g as measured using a Krebs Stormer Model KU-1 with a paste spindle. In some embodiments, the viscosity of the coating composition is at least 150 g or at least 200 g or at least 250 g or at least 300 g or at least 400 g or at least 500 g. In some embodiments, the viscosity exceeds 1099 g, which is the measuring capacity of some units.

In some embodiments, the coating composition contains at least 5 weight percent water or at least 10 weight percent or 12 weight percent or at least 15 weight percent. In some embodiments, the coating composition contains at most 30 weight percent water or at most 25 weight percent or most 22 weight percent or at most 20 weight percent or at most 18 weight percent. For example, in some embodiments, the coating composition contains from 5 to 30 weight percent water, or from 10 to 25 weight percent or from 12 to 20 weight percent or from 15 to 18 weight percent. Note that in some cases the acrylic polymer binder, the filler, and/or other additives in the coating composition may be added as solutions, emulsions or suspensions that contain water; in this case, only a small amount of additional water may be needed to achieve desirable levels of water in the overall coating composition.

In some embodiments, the coating composition has a pH of at least 6 or at least 7 or at least 8. In some embodiments, the coating composition has a pH of at most 9 or at most 10 or at most 11. Acids such as acetic acid, formic acid, and citric acid or bases such as ammonia or potassium hydroxide may be added to the coating composition to provide the desired pH.

In some embodiments, the coating composition further contains an organic solvent that is miscible with water. Examples of suitable organic solvents include alcohols and glycols. In some embodiments, the quantity of organic solvent is no more than 8 weight percent of the coating composition, including water, or no more than 6 weight percent or no more than 5 weight percent or no more than 4 weight percent or no more than 3 weight percent. The quantity of organic solvents may be 0 weight percent, but in some embodiments, the quantity of organic solvent is at least 0.5 weight percent or at least 1 weight percent or at least 1.5 weight percent or at least 2 weight percent. In some embodiments, the quantity of organic solvent is low enough that volume percent and weight percent are not materially different, so the concentrations previously described can also apply to volume percent.

Use of Coating Composition and Resulting Coatings

Among other uses, the coating composition can be used to make an exterior coating on a substrate, and particularly to make the finish coat in an ETFS exterior. First, the coating composition is applied directly or indirectly to a substrate. Second, the aqueous composition is allowed to dry and harden. Each of these steps is well-known.

In some embodiments, the substrate is a vertical surface, such as a wall or more particularly an exterior wall of a structure. Examples of appropriate substrates for a wall include any known building surface material, such as wood, plaster, concrete, or synthetic plank. In a particular embodiment, the substrate comprises the insulation layer and the base coat of an EIFS, and the coating composition is used to form the finish coat of the EIFS.

The coating composition can be applied by known means. For example, depending on viscosity, it may be applied and spread with a trowel or may be brushed or rolled. If the coating composition is applied with a trowel, it may also be smoothed or textured, and designs may be added. It is known that some weather conditions, such as rain or extreme cold or humidity, may be inappropriate for applying the coating composition and may be avoided.

In some embodiments, the coating composition is applied with an average thickness of at least 0.05 cm or at least 0.1 cm or at least 0.15 cm. In some embodiments, the coating composition is applied with an average thickness of at most 3 cm or at most 1 cm or at most 0.5 cm or at most 0.4 cm or at most 0.3 cm.

After it is applied, the coating composition is permitted to dry and harden. The time needed for the coating composition to dry may vary depending on the water content of the coating composition, the thickness of the coating and ambient conditions such as temperature and humidity. In some embodiments, a 1/16 inch (0.16 cm) coating of the coating composition dries to the touch under conditions in the Test Methods in no more than 2 hours after it is applied or no more than 1.5 hours or no more than 1 hour or no more than 45 minutes or no more than 30 minutes. In some embodiments, a 1/16 inch coating of the coating composition dries to the touch under conditions in the Test Methods in at least 5 minutes after it is applied, or at least 10 minutes or at least 15 minutes or at least 20 minutes or at least 30 minutes. In some embodiments, a 1/16 inch coating of the coating composition dries through under conditions in the Test Methods in no more than 4 hours after it is applied or no more than 3.5 hours or no more than 3 hours or no more than 2.5 hours. In some embodiments, a 1/16 inch coating of the coating composition dries through under conditions in the Test Methods in at least 1 hour after it is applied, or at least 1.5 hours or at least 2 hours. In some embodiments, these targets can be met even when the composition contains no more than 0.1 weight percent polyamine. After drying is complete, the coating composition produces a dry coating attached directly or indirectly to the selected substrate. In an EIFS, the dry coating may be the finish layer on an EIFS that contains an insulation layer and a base coat as previously described.

The dry coating has contents derived from the solid contents of the coating composition. For example, the dry coating may contain: a) filler with the description and quantities previously described, excluding aqueous solvent; b) OAP binder in a quantity suitable to adhere the filler to the substrate; c) from 0 to 8 weight percent other additives, based on the total weight of dry ingredients.

Its thickness is roughly equal to the thickness of the coating composition that was applied.

The quantities and descriptions of these ingredients in the dry coating are similar to the descriptions for the coating composition, excluding water. The dry coating typically contains less than 5 weight percent water or less than 3 weight percent or less than 1 weight percent.

In some embodiments, the dry coating suffers no visible damage in a rain test (as described in the Test Methods), after drying at 25°C for no more than 5 hours or no more than 4 hours or no more than 3 hours or no more than 2 hours. In some embodiments, the dry coating shows visible damage in a rain test (as described in the Test Methods), after drying at 25°C for only 30 minutes or for only 1 hour.

Test Methods

Unless stated otherwise, measurements listed in this application are made using the following test methods:

Kubelka-Munk Scattering Coefficient Measurement

The scattering coefficient (S/Mil) is a measure of the opacity of the OAPs. A 7-mil wet film of the OAP was drawn over a sheet of black vinyl that was measured for thickness in four small defined areas with an Ames Gauge. The film is dried for 2 h at low relative humidity (<40% R.H.). The reflectance of the dry film is measured by a Gardner Instrument Reflectometer over the four defined areas. The thickness of the dried film is also determined over the same defined areas using the Ames Gauge. The Scattering coefficient is calculated for each of defined areas as: 100

where R is Reflectance and T is film thickness in mils. The four S/Mil measurements were then averaged to obtain the S/Mil for the film.

Collapse

Collapse is an indication of the ability of an opaque polymer to resist the forces of drying acting on the walls of the internal micro void. These forces are greatest at high humidity, which causes the particles to dry slowly. Collapse is determined using essentially the same procedure that is used in determining S/Mil except that a second drawdown is dried overnight at 75% R.H., then dried at <40% R.H. for 1 h.

I High humidity S/mil \

% Collapse = 1 - - x 100

I Low humidity S/mil j

Examples

The following examples illustrate specific embodiments of the invention, but do not limit the broadest scope of the invention.

The materials in Table 1 are used for the Examples:

Table 1

Preparation of OAP Binder 1 (OAP I )

Core #1 is an aqueous dispersion of polymer particles (66 weight percent methyl methacrylate/34 weight percent methacrylic acid, solids 32.0%, z-average particle size of 135 nm) prepared substantially as described in US 6,020,435.

Monomer emulsion 1 (ME 1) is made by mixing deionized water (125.0 g), Disponil FES-32 emulsifier (10.0 g), styrene (424.2 g), methacrylic acid (7.0 g), linseed oil fatty acid (2.8 g), acrylonitrile (112.0 g), and divinyl benzene (14.0 g).

Monomer emulsion 2 (ME 2) is prepared by mixing deionized water (240 g), Disponil FES-32 emulsifier (17.0 g), butyl acrylate (431.46 g), methyl methacrylate (430.54 g), 2-ethylhexyl acrylate (124.44 g), aceto acetoxy ethyl methacrylate (25.5 g) and methacrylic acid (7.96 g),

Monomer emulsion 3 (ME 3) is prepared by mixing DI water (54.0 g), Disponil FES-32 emulsifier (3.0 g), butyl acrylate (104.4 g), methyl methacrylate (75.6 g), and 4-hydroxy TEMPO (3.0 g), was fed to the kettle over 5 min.

A 5-liter, four necked round bottom flask is equipped with a paddle stirrer, thermometer, N2 inlet and reflux condenser. Deionized water (475 g) is added to the kettle and heated to 89 °C under N?. Sodium persulfate (NaPS, 3 g in 25 g water) is added to vessel, immediately followed by Core #1 (125 g). Monomer emulsion 1 is added to the kettle over 45 min. The temperature of the reaction mixture is allowed to increase to 84 °C after 15 min and allowed to increase to 92 °C after 25 min. From 2 minutes after the start of ME 1 addition, a solution of methacrylic acid (5.6 g) in DI water (40 g) is added to the flask. Upon completion of the ME 1 feed, the reaction is cooled to 60 °C. When the kettle temperature reaches 80 °C., an aqueous mixture of ferrous sulfate and EDTA (20 g, 0.1 wt. % FeSO4, and 2 g, 1 wt. % EDTA) is added to the kettle. When the kettle temperature reaches 60 °C, co-feeds are both added simultaneously to the kettle at a rate of 1.2 g/mins each: (a) a solution of t-butylhydroperoxide (t-BHP 1.9 g) and NaPS (5.0 g) mixed with deionized water (100 g); and (b) a separate solution of isoascorbic acid (IAA, 2.6 g in 100 g water). Two min after the start of charging the co-feed solutions, ME 2 is added to the kettle over 55 min while allowing the temperature to rise to 86 °C without providing any external heat. Upon completion of ME 2 addition, the co-feed solutions are stopped, and the batch is held for 5 min at 80-86°C. A solution of ammonium hydroxide (5 g, 28 wt. % aq.) mixed with deionized water (5.0 g) is added to the kettle along with hot (90 °C) deionized water (175 g)-

ME 3 is fed to the kettle over 5 min. Immediately after the ME 3 feed addition is complete, ammonium hydroxide (35.0 g, 28 wt. % aq.) mixed with deionized water (35 g) is added to the kettle over 2 min. When ammonium hydroxide has been added, the batch is held for 5 min. The addition the co-feed solutions is resumed at 1.2 g/min until completion, whereupon the dispersion is cooled to 25 °C. While cooling, additional co-fccds arc both added simultaneously to the kettle at a rate of 1.30 g/min: (a) a solution of t-butyl hydroperoxide (1.5 g) in deionized water (25 g); and (b) a separate solution of IAA (0.7 g) in water (25 g). After the second co-feed is added, the dispersion is filtered to remove any coagulum. The filtered opaque acrylic dispersion (OAP) had a solids content of 48.7%. The S/mil was measured to be 1.03 with Collapse of 0.0%.

Synthesis of OAP Binder 2

The procedure for making OAP Binder 1 is repeated, but: ME 2 contains deionized water (240 g), Disponil FES-32 emulsifier (17.0 g), butyl acrylate (679.8 g), methyl methacrylate (316.2 g), diacetone acrylamide (DAAm, 12.0 g) and methacrylic acid (12.0 g). When the flask reaches 45°C, a slurry solution of adipic dihydrazide (ADH, 6 g in 30 g water) is added to the flask before the ACRYSOL™ ASE-60 is added. The filtered opaque OAP Binder 2 dispersion has a solids content of 48.3%.

Synthesis of OAP Binder 3

The procedure for making OAP Binder 2 is repeated, but an additional amount of 0.975 g of ADH is added before formulation into EIFS coating.

Synthesis of OAP Binder 4

The procedure for making OAP Binder 1 is repeated, but ME 2 contains DI water (240 g), Disponil FES 32 emulsifier (17.0 g), butyl acrylate (679.8 g), methyl methacrylate (305.4 g), acetoacetoxy ethyl methacrylate (22.8 g) and methacrylic acid (12.0 g). The filtered OAP Binder 4 dispersion had a solids content of 48.6%. Synthesis of OAP Binder 5

The procedure for making OAP Binder 4 is repeated, but 0.466 g of amine is added before formulation into EIFS coating.

Finish Coating Formulations

The ingredients shown in Table 2 are mixed to form eight homogeneous coating formulations by mixing the binder solution, defoamer and TiO?, followed by pigments & fillers, followed by thickener mixed in water and other ingredients, water and then ammonia. Examples 2 through 11 are examples of the invention. Example 1 is a comparative examples using a commercial binder used in the EIFS industry.

Drying Time Tests

Each coating formulation is troweled onto a metal panel at 1/16” thick. Dry-To-Touch Time is tested at 15 minutes, 30 minutes and then in subsequent 30-minute intervals. After the coatings are Dry- To-Touch, Dry-Through Times arc tested in 30-minutc intervals. Dry-To-Touch Time is the time at which no coating adheres to the finger after touching the coating with light pressure. Dry-Through Time is the time at which no mark is left on the coating after twisting a thumb 90° through the coating. The results are recorded on Table 2.

Rain Test

An EIFS admix contains 287 lbs. EI-2000 binder solution, 8.21 lbs. WALOCEL™ MT 40000PV thickener dissolved in 247.48 lbs. water with a few drops of ammonium hydroxide to initiate thickening, 1.99 lbs. Nopco NXZ defoamer, 789.94 lbs. Unimin 50-30 sand, 1.8 lbs. Kathon LX 1.5% preservative and 2.00 lbs. Texanol coalescent. A cementitious base coat contains equal weights of the EIFS admix and Portland cement, plus 7 weight percent water. An EIFS substrate is prepared by spreading the cementitious base coat on top of a 1” foam block. Mesh is then embedded into the admix/cement mixture using a hand trowel. The substrate is allowed to dry fully. Each coating formulation is troweled onto a prepared EIFS substrate at a thickness of 1/16 inch. Samples are allowed to cure for a period of 2 hours (2 Hour Rain Test) or 4 hours (4 Hour Rain Test) and then are placed under a spray nozzle that sprays water at the coatings at a flow rate of approximately 3 gallons/minute. Coatings are left in the water spray for a period of 2 hours in the case of the 4 Hour Rain Test or a period of 3 hours in the case of the 2 Hour Rain Test. Damage to the coating is visually observed. Table 2

* - Hollow sphere particles make up about 37% of the measured PVC.

Rain Test Results: 0 = no noticeable change, 1 = slight exposure of filler, 2 = moderate exposure of filler, 3 = areas of coating complete washed off to the substrate.

Claims

CLAIMS:

1. A coating composition that comprises:

(a) inorganic filler;

(b) a film-forming opacifying acrylic polymer binder that comprises hollow sphere particles and is present in a concentration effective to bind the filler and other solid components of the coating composition to a substrate; and

(c) water in a quantity sufficient to fully wet the dry ingredients and provide a slurry, wherein a combined pigment volume concentration of inorganic filler and hollow sphere particles in the coating composition is at least 65, and the coating composition has a viscosity of at least 100 g.

2. The coating composition of claim 1 wherein the combined pigment volume concentration of inorganic filler and hollow sphere particles in the coating composition is from 71 to 90.

3. The coating composition of Claim 1 wherein the coating composition has a viscosity of at least 200 g.

4. The coating composition of Claim 1 wherein the coating composition contains from 8 to 20 weight percent opacifying acrylic polymer binder.

5. The coating composition of Claim 1 wherein the opacifying acrylic polymer binder contains (a) from 10 to 50 weight percent of a film-forming low Tg acrylic polymer that has a glass transition temperature of no more than 45°C; and (b) shells of high-Tg polymer that has a glass transition temperature of at least 55°C and that encloses void spaces, and wherein weight percentages are based on dry weight of the binder excluding water.

6. The coating composition of Claim 5 wherein the film-forming low Tg acrylic polymer comprises repeating units from a cross-linking monomer.

7. The coating composition of Claim 1 wherein the coating composition contains less than 0.1 weight percent of an organic polyamine, based on the dry weight of the coating composition excluding water.

8. The coating composition of Claim 1 wherein the coating composition has a viscosity of at least 300 g.

9. The coating composition of Claim 1 wherein:

(a) the combined pigment volume concentration of inorganic filler and hollow sphere particles in the coating composition is 75 to 86;

(b) the coating composition contains from 8 to 20 weight percent opacifying acrylic polymer binder wherein the opacifying acrylic polymer binder contains (a) from 10 to 50 weight percent of a film-forming low Tg acrylic polymer that has a glass transition temperature of no more than 45°C; and (b) shells of high-Tg polymer that has a glass transition temperature of at least 55°C and that encloses void spaces; and

(c) the coating composition has a viscosity of at least 200 g. wherein weight percentages are based on the dry weight excluding water.

10. The coating composition of Claim 9 wherein the film-forming low Tg acrylic polymer comprises repeating units from a cross-linking monomer.

1 1 . The coating composition of Claim 9 wherein the coating composition contains less than 0. 1 weight percent of an organic polyamine, based on the dry weight of the coating composition excluding water.

12. The coating composition of Claim 11 wherein a coating 0.16 cm thick dries through in no more than 3 hours after it is applied.

13. A process to coat an architectural substrate comprising the steps of

(a) applying the coating composition in any one of Claims 1 to 12 directly or indirectly to the architectural substrate; and

(b) permitting the coating composition to dry.

14. The process of Claim 11 wherein the coating composition is applied in a thickness from 0.1 cm to 3 cm.

15. The process of Claim 11 wherein the architectural substrate comprises an insulation layer and a base coat of an exterior insulation and finish system (EIFS), and the coating composition is used to form a finish coat of the EIFS.