EIFS base coat formulation

Abstract

The base coat layer in an EIFS cladding that contains cement, filler and a polymer binder can have an improved balance of properties when the layer also contains at least 0.1% by weight of a cellulose ether with a viscosity of at least 30,000 cP in water at 2% concentration and 20? and contains no or limited quantities of starch ether and polyacrylamide.

Description

[0001] EIFS BASE COA T FORMULATION

[0002] FIELD

[0003] This application relates to base coat formulations that provide enhanced adhesion for use in exterior insulation and finish (EIFS) cladding for buildings.

[0004] INTRODUCTION

[0005] Exterior insulation and finish systems (EIFS) are used on the outside of buildings to provide good thermal insulation, weatherability and appearance at a low price. EIFS comprise at least three layers applied to the exterior wall of the building:

[0006] 1. A layer of insulation, which is typically foam insulation board such as expanded polystyrene board, adhered directly or indirectly to a wall substrate by adhesive or mechanical fasteners;

[0007] 2. A layer of cementitious base coat adhered directly or indirectly to the insulation layer; and

[0008] 3. A layer of finish coat adhered directly or indirectly to the base coat, which comprises a coating material that provides wcathcrability and the desired appearance.

[0009] 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.

[0010] The base coat layer is usually made by trowelling an aqueous base coat formulation onto the insulation layer with a thickness of l / 8thof an inch to Yi inch. The base coat formulation usually comprises the following components dissolved or suspended in an aqueous carrier: (a) cement, (b) filler, (c) optionally a fibrous reinforcement, such as a mesh; and (d) a redispersible powder. The base coat formulation often further contains one or more thickeners and rheology modifiers, such as cellulose ethers, starch ethers, anionic copolymers and clays. The thickeners increase the viscosity of the base coat to prevent sagging and dripping after the base coat is applied. They can also improve water retention and open time for the base coat formulation.

[0011] In many cases, the base coat formulation is also used as an adhesive to adhere the insulation layer to the exterior wall of the building.

[0012] The base coat must meet several different criteria. It must have high viscosity, so that it can be applied to a vertical substrate and dry without dripping or slumping and so that can be an effective adhesive when wet. It must have good adhesion both to concrete and to foamed insulation boards. It must dry quickly after it is applied, both to reduce the risk from rain and to allow quicker installation of the EIFS. On the other hand, it must also be workable (easy to apply and spread smoothly and evenly) and must remain workable for a reasonable open time before it is applied. When dry, the base coat must minimize infiltration of water. Base coats that improve this balance of properties are desired.

[0013] SUMMARY

[0014] One aspect of this invention is an EIFS cladding that contains (1) a layer of rigid insulation; (2) a layer of base coat adhered directly or indirectly to the layer of insulation, which optionally contains an embedded fibrous reinforcement; and (3) a layer of finish coat adhered directly or indirectly to the layer of base coat, wherein the layer of base coat comprises:

[0015] (a) cement;

[0016] (b) filler;

[0017] (c) at least 1 % by weight of a polymer binder;

[0018] (d) at least 0.1% by weight of a cellulose ether with a viscosity of at least 30,000 cP, at 20°C and 2% concentration in water; and

[0019] (e) from 0 to 19 weight percent starch ether and from 0 to 1.2 weight percent polyacrylamide, based on the weight of cellulose ether.

[0020] A second aspect of this invention is a process to make an EIFS cladding, which process comprises the steps of: (1) adhering a layer of rigid insulation to the exterior wall of a building; (2) applying a layer of base coat formulation and optionally a fibrous reinforcement directly or indirectly to the layer of rigid insulation, and allowing the base coat formulation to dry; and (3) applying a layer of finish coat formulation directly or indirectly to the layer of base coat, and allowing the finish coat formulation to dry, wherein the base coat formulation comprises the following dry components in an aqueous carrier:

[0021] (a) cement;

[0022] (b) filler;

[0023] (c) at least 1 % by weight of a polymer binder;

[0024] (d) at least 0.1% by weight of a cellulose ether with a viscosity of at least 30,000 cP, at 20°C and 2% concentration in water; and

[0025] (e) from 0 to 19 weight percent starch ether and from 0 to 1.2 weight percent polyacrylamide, based on the weight of cellulose ether, wherein weight percentages are based on the weight of dry components and excluding aqueous carrier, unless otherwise stated.

[0026] The inventive base coat formulations, in some embodiments, can provide a desirable balance of adhesion, cure time, water uptake and open time.

[0027] DETAILED DESCRIPTION

[0028] This invention relates to EIFS cladding. The EIFS cladding contains, in some embodiments, (1) a layer of rigid insulation; (2) a layer of base coat adhered directly or indirectly to the layer of insulation, which optionally contains an embedded reinforcing mesh; and (3) a layer of finish coat adhered directly or indirectly to the layer of base coat. The invention also relates to a process to make the EIFS cladding. In some embodiments of the process, the base coat layer is made by applying an aqueous base coat formulation directly or indirectly onto the rigid insulation layer.

[0029] Panels of rigid insulation are well known and commercially available. They typically comprise foamed polymer such as expanded polystyrene (EPS) or polyisocyanurate. Suitable examples are sold under the trademarks Polyshield, Insulfoam and GoBoard.

[0030] The rigid insulation is adhered to the exterior wall of a building. The exterior wall may comprise surfaces commonly used for building structures, such as wood, cement board, bricks, concrete or concrete block. The insulation may be attached to the wall mechanically, such as with screws, nails or anchors. Alternatively, the insulation may be attached to the wall by an adhesive. In some embodiments, the base coat formulation is used as an adhesive to adhere the insulation to the wall.

[0031] In some embodiments, a water barrier layer and / or a water-channel layer is between the insulation and the wall surface. This layer is sometimes referred to as house wrap. Some water barrier house wraps have integrated water channels. Suitable house wraps arc commercially available under the trademarks Tyvek Stuccowrap and GreenGuard RainDrop. Like the insulation, the house wrap may be attached mechanically or using adhesive.

[0032] The base coat formulation is applied directly or indirectly to the insulation layer. (“Indirectly” means that optionally one or more intervening layers may be between the insulation layer and the base coat, such as a moisture barrier, a foil or an adhesion layer that improves the ability of the base coat to adhere to the insulation.). In some embodiments, the base coat formulation comprises the following dry components in an aqueous carrier:

[0033] (a) cement;

[0034] (b) filler;

[0035] (c) at least 1 % by weight of a polymer binder; and

[0036] (d) at least 0.1% by weight of a cellulose ether with a viscosity of at least 30,000 cP, at 20°C and 2% concentration in water, wherein weight percentages are based on the weight of dry components and excluding aqueous carrier, unless otherwise stated. Further, in some embodiments, the base-coat comprises only low levels or essentially no starch ether and polyacrylamide viscosity modifiers.

[0037] The base coat formulation contains cement. The ASTM recognizes five categories of cement: Type 1 (ordinary Portland cement); Type 2 (moderate sulfate resistant cement); Type 3 (rapid hardening cement), Type 4 (low heat cement) and Type 5 (high sulfate resistant cement). Any of these cements may be used in the base coat formulation. In some embodiments, the cement is ordinary Portland cement. In some embodiments, the cement is a variation of ordinary Portland cement, known as white cement. In some embodiments, the cement is a more specialized cement, such as a high alumina cement or a calcium sulfoaluminate cement. Suitable cements are commercially available. The base coat formulation should contain enough cement to form an effective base coat for an EIFS cladding. In some embodiments, the base coat formulation contains at least 15 weight percent cement or at least 20 weight percent or at least 22 weight percent or at least 25 weight percent or at least 30 weight percent or at least 35 weight percent, based on the dry components and excluding aqueous carrier. In some embodiments, the base coat formulation contains at most 60 weight percent cement or at most 55 weight percent or at most 50 weight percent or at most 45 weight percent, based on the dry components and excluding aqueous carrier. (The “dry components” are the cement, filler, redispersible powder and cellulose ether and any other components of the base coat formulation that are solids at 25°C and atmospheric pressure. The “dry components” of the base coat formulation exclude any reinforcing mesh.)

[0038] The base coat formulation contains filler. In some embodiments, the filler comprises inorganic materials, and in some embodiments the filler consists essentially of inorganic materials. Examples of inorganic fillers include silica sand, quartz sand, kaolin, calcium carbonate, magnesium carbonate, talc or mixture thereof. Suitable inorganic fillers are commercially available.

[0039] The filler particles have a particle size suitable for use in a coating composition. In some embodiments, at least 95 percent of the filler particles have a diameter of no more than 1.5 mm or no more than 1.2 mm or no more than 1.0 mm or no more than 0.8 mm. In some embodiments, at least 95 percent of the filler particles have a diameter of at least 0.01 mm or at least 0.05 mm or at least 0.06 mm or at least 0.1 mm.

[0040] In addition to filler, the base coat formulation optionally contains pozzolans or inorganic pigments or both. Examples of pozzolans include fly ash, calcined kaolin, pumices, or fumed silica. Pozzolans and their use with cement are well-known and described in US Patent 9, 181 , 131B2. Suitable pozzolans are commercially available. Examples of inorganic pigments include titanium dioxide, carbon black, iron oxides, chromium oxide and cobalt oxide. Suitable inorganic pigments are commercially available.

[0041] In some embodiments, the fillers, pozzolans and inorganic pigments make up at least 20 weight percent of the dry components in the base coat formulation or at least 24 weight percent or at least 30 weight percent or at least 40 weight percent or at least 45 weight percent or at least 50 weight percent. In some embodiments, the fillers, pozzolans and inorganic pigments make up at most 80 weight percent of the dry components in the base coat formulation or at most 70 weight percent or at most 65 weight percent or at most 60 weight percent or at most 55 weight percent, based on the dry components and excluding aqueous carrier.

[0042] In some embodiments, the fillers, pozzolans and inorganic pigments make up at least 40 volume percent of the dry components in the base coat formulation, or at least 45 volume percent or at least 50 volume percent or at least 55 volume percent or at least 60 volume percent or at least 65 volume percent. In some embodiments, the fillers, pozzolans and inorganic pigments make up at most 95 volume percent of the dry components in the base coat formulation, or at most 90 volume percent or at most 85 volume percent or at most 80 volume percent.

[0043] The base coat formulation contains a polymer binder that is suitable for use in coating formulations. In some embodiments, the polymer binder is water-dispersible. In some embodiments, the polymer binder is a dry powder before the components are mixed with aqueous carrier, called a “redispersible powder”. The redispersible powder contains an organic polymer and optionally a surfactant that can form a stable polymer emulsion when mixed with water. In some embodiments, the redispersible powder is made by (1) forming a polymer emulsion containing the organic polymer and the surfactant (if any) and (2) drying the emulsion to form the powder such as by spray drying. In such case, the redispersible powder may contain both the organic polymer and the surfactant that were present in the emulsion. In some embodiments, redispersible powders may sometimes further contain additives such as anti-caking agents. Calcium carbonate and kaolin are examples of common anticaking agents.

[0044] In some embodiments, the polymer binder contains an acrylic copolymer, vinyl ester copolymer or styrene-butadiene (SB) copolymer.

[0045] In some embodiments, the polymer binder contains a vinyl ester copolymer. Vinyl ester copolymers contain repeating units derived from one or more vinyl ester monomers, such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate, vinyl pivalate, and vinyl esters of C-branched monocarboxylic acids having 9 to 11 carbon atoms, such as vinyl versatate. In some embodiments, the vinyl ester copolymer comprises vinyl acetate. In some embodiments, the vinyl ester copolymer comprises both vinyl acetate and vinyl esters of C-branched monocarboxylic acids having 9 to 11 carbon atoms.

[0046] In some embodiments, the vinyl ester copolymer further comprises repeating units derived from ethylene or vinyl chloride. For example, vinyl ester-ethylene copolymers may contain at least 1 weight percent repeating units derived from ethylene or at least 5 weight percent or at least 10 weight percent, and vinyl ester-ethylene copolymers may contain at most 60 weight percent repeating units derived from ethylene or at most 50 weight percent.

[0047] In some embodiments, the vinyl ester copolymer further comprises repeating units derived from an acrylic or methacrylic ester such as n-butyl acrylate or 2-ethyl hexyl acrylate. For example, vinyl ester-acrylic ester copolymers may contain 30 to 90 weight percent repeating units derived from vinyl ester, 1 to 60 weight percent repeating units derived from acrylic ester and 1 to 40 weight percent repeating units derived from ethylene. In some embodiments, the vinyl ester copolymer comprises no measurable quantity of acrylic or methacrylic ester.

[0048] Vinyl ester copolymers may further contain a small quantity of repeating units derived from ethylenically unsaturated monocarboxylic acids or dicarboxylic acids or their anhydrides, ethylenically unsaturated carboxamides or carbonitriles, ethylenically unsaturated sulfonic acids and their salts and vinyl silanes. Examples of common comonomers in this group include acrylic acid, methacrylic acid, acrylamide, acrylonitrile, vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tripropoxysilane, vinyl triisopropoxysilane, and sodium vinyl sulfonate. In some embodiments, the vinyl ester copolymer contains 0 to 2 weight percent of repeating units derived from such comonomers, or 0 to 1 weight percent or 0.5 to 1 weight percent.

[0049] Examples of suitable vinyl ester copolymers and their production are described in US Patent 6,890,975. In some embodiments, the vinyl ester copolymer is a vinyl acetate-ethylene (VAE) copolymer. In some embodiments, the vinyl ester copolymer contains a vinyl ester of versatic acid (VEOVA).

[0050] In some embodiments, the polymer binder contains an acrylic copolymer. Examples of acrylic polymers include styrene acrylic copolymers such as styrene acrylonitrile copolymers.

[0051] In some embodiments, the polymer binder has a minimum film formation temperature of at least -20°C or at least -10°C or at least -5°C or at least 0°C. In some embodiments, the polymer binder has a minimum film formation temperature of at most 25°C or at most 20°C.

[0052] In some embodiments, the polymer binder has a glass -transition temperature of at least -30°C or at least -20°C or at least -10°C or at least -5°C or at least 0°C. In some embodiments, the polymer binder has a glass-transition temperature of at most 40°C or at most 30°C or at most 25°C.

[0053] In many embodiments, the polymer binder further comprises a surfactant. In some embodiments, the surfactant is an anionic surfactant. Examples of nonionic surfactants include nonylphenol ethoxylates and fatty (C6 to C30) alcohol ethoxylates, such as TERGITOL™ 15-S-40 and TERGITOL™ NP10, which are commercially available from The Dow Chemical Company.

[0054] In some embodiments, the polymer binder and surfactant are selected such that the polymer binder forms an emulsion with a particle size of at least 200 nm or at least 400 nm or at least 500 nm or at least 600 nm. In some embodiments, the polymer binder and surfactant are selected such that the polymer binder forms an emulsion with a particle size of at most 1000 nm or most 800 nm.

[0055] In some embodiments, the polymer binder and surfactant are selected such that the polymer binder forms an emulsion which is stable in a cementitious environment. The cement used in the base coat creates an alkaline environment that is high in calcium ions. This environment can cause some emulsions to break down. Other combinations of polymer binder and surfactant are known to form stable emulsions in this environment, and the combinations that form stable emulsions may be advantageously used in base coats of this invention.

[0056] Examples of suitable polymer binders are commercially available, such as under the DOW™ Latex Powder 210 and DOW™ Latex Powder 212 trademarks. Other polymer binders can be made in aqueous dispersion by emulsion copolymerization of vinyl ester monomers and ethylene monomer according to known processes, such as are described in Lindemann, Vinyl Acetate / Ethylene Emulsion Copolymers, Paint Manufacture, September 1968, at 30-36, and US Patent 5,576,384 and US Application 2009 / 0069495 AL The resulting dispersion can be spray-dried to produce a redispersible powder.

[0057] In some embodiments, the quantity of redispersible powder in the base coat formulation 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 or at least 2.2 weight percent, based on the weight of dry components and excluding aqueous carrier. In some embodiments, the quantity of redispersible powder in the base coat formulation is at most 8 weight percent or at most 5 weight percent or at most 4 weight percent or at most 3 weight percent or at most 2.5 weight percent, based on the weight of dry components and excluding aqueous carrier. In many embodiments, the polymer binder makes up roughly from 70 to 80 weight percent of the redispersible powder. Therefore, in some embodiments, the quantity of polymer binder in the base coat formulation is at least 0.4 weight percent or at least 0.75 weight percent or at least 1 .2 weight percent or at least 1.5 weight percent or at least 2 weight percent, based on the weight of dry components and excluding aqueous carrier. In some embodiments, the quantity of polymer binder in the base coat formulation is at most 6 weight percent or at most 4 weight percent or at most 3 weight percent or at most 2.5 weight percent or at most 2 weight percent, based on the weight of dry components and excluding aqueous carrier.

[0058] In some embodiments, the weight ratio of cement to redispersible powder in the base coat formulation is at least 5: 1 or at least 6: 1 or at least 7: 1 or at least 8:1 or at least 9: 1 or at least 10: 1. In some embodiments, the weight ratio of cement to redispersible powder in the base coat formulation is at most 30: 1 or at most 20: 1 or at most 18: 1 or at most 16: 1 or at most 14:1 or at most 12: 1. In some embodiments, the weight ratio of cement to polymer binder in the base coat formulation is at least 4: 1 or at least 5: 1 or at least 6: 1 or at least 7 : 1 or at least 8 : 1 or at least 9: 1. In some embodiments, the weight ratio of cement to polymer binder in the base coat formulation is at most 25: 1 or at most 20: 1 or at most 18: 1 or at most 16: 1 or at most 14: 1 or at most 12:1.

[0059] The base coat formulation contains a cellulose ether with a viscosity of at least 30,000 cP, at 20°C and 2% concentration in water. Cellulose ethers are based on cellulose, which is made up of repeating anhydroglucose units that have multiple pendant hydroxy groups. In cellulose ethers, some hydrogen atoms in the pendant hydroxy groups have been substituted with alkoxyl moieties such as methyl, ethyl or propyl moieties (alkyl substitution), or with hydroxyalkyl moieties such as hydroxy methyl, hydroxyethyl or hydroxy propyl moieties (hydroxyalkyl substitution), or with both alkyl and hydroxyalkyl moieties. Examples of suitable cellulose ethers include methyl cellulose, ethyl cellulose, n- and i-propyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose and blends thereof.

[0060] Cellulose ethers are often characterized by degree of substitution (“DS”), which is the average number of pendant hydroxy groups in each anhydroglucose unit that have alkyl or hydroxyalkyl substitution, as determined by the Zeisel method. In some embodiments, the average degree of substitution for the cellulose ether is at least 0.75 or at least 0.95 or at least 1.2 or at least 1.5 or at least 1.7 or at least 1.9. In some embodiments, the average degree of substitution for the cellulose ether is at most 3 or at most 2.7 or at most 2.5 or at most 2.3 or at most 2.1.

[0061] In some embodiments, the cellulose ether is a hydroxyalkyl cellulose ether such as hydroxyethyl cellulose, with a degree of substitution from 1.1 to 2.5 or from 1.2 to 2.0. In some embodiments, the cellulose ether is a hydroxyalkyl methylcellulose such as hydroxyethyl methylcellulose. In some embodiments, the degree of methyl substitution (DS (M)) in the hydroxyalkyl methyl cellulose is from 1.2 to 2.1 or from 1.3 to 1.7. In some embodiments, the degree of hydroxy alkyl substitution (DS (HA)) in the hydroxyalkyl methyl cellulose is from 0.05 to 0.8 or from 0.15 to 0.4.

[0062] In some embodiments, the cellulose ether is a substantially linear cellulose ether.

[0063] In some embodiments, the cellulose ether is crosslinked cellulose ether. Crosslinked cellulose ethers (sometimes called “XCE” or “branched cellulose ethers” or “gel-like cellulose ethers”) and processes to make them are described in references such as US Patent Publication US2022 / 0112311 Al and PCT Patent Publications W02020 / 223039 and WO2022 / 235562 Al.

[0064] In some embodiments, the degree of crosslinking is high enough that the XCE has higher viscosity than the equivalent non-crosslinked cellulose ether, but the degree of crosslinking is not so high that the XCE contains significant water-insoluble material. In some embodiments, the XCE has a viscosity at least 15% higher than the viscosity of an equivalent non-crosslinked cellulose ether, or at least 20% higher or at least 30% higher or at least 50% higher. All viscosities are in a 2% aqueous solution tested according to the Test Methods.

[0065] In some embodiments, the XCE is made by reacting a cellulose ether, as previously described, with a crosslinking agent. Suitable crosslinking agents are described in the previous references on making XCE. Examples of suitable crosslinking agents include diglycidyl ethers such as those sold under the Epilox trademark. In some embodiments, the equivalent ratio of crosslinking agent to cellulose ether (moles of crosslinking agent per mole of anhydroglucose unit) is at least 0.0001 or at least 0.0005 or at least 0.001. In some embodiments, the equivalent ratio of crosslinking agent to cellulose ether is at most 0.05 or at most 0.03 or at most 0.02 or at most 0.01 or at most 0.005.

[0066] Crosslinking in cellulose ethers can be characterized by the crossover value (COV) of the cellulose ether, which is the angular frequency (co) at which the storage modulus (G’ ) of a 1 weight percent solution of the cellulose ether in water is equal to the loss modulus (G”), when measured according to the Test Methods. See PCT Patent Publication WO2022 / 235562 Al. In some embodiments, the COV of the crosslinked cellulose ether is at least 1.5 rad / s or at least 2 rad / s. In some embodiments, the COV of the crosslinked cellulose ether is at most 8 rad / s or at most 7 rad / s. In some embodiments, the ratio of:

[0067] [COV of the XCE] / [COV of the equivalent uncrosslinked cellulose ether] is at least 0.07 or at least 0.1 and / or is at most 0.5 or at most 0.4.

[0068] In some embodiments, the viscosity of the cellulose ether is at least 35,000 cP or at least 40,000 cP or at least 45,000 cP or at least 50,000 cP or at least 55,000 cP. In some embodiments, the viscosity is at most 200,000 cP or at most 150,000 cP or at most 100,000 cP. The viscosities are measured in a 2% aqueous solution according to the Test Methods.

[0069] Cellulose ethers with suitable viscosity are commercially available, such as under the WALOCEL, METHOCEL and CELLOSIZE names. Others can be produced by known processes. See, for example, US Patent 4,845,206 and Harika K et al., Basic Concepts of Cellulose Polymers- A Comprehensive Review, 3(3) Archives of Pharmacy Practice 202-216 (2012). In many cases, cellulose ethers can be produced by a two-step process. In the first step, cellulose is contacted with aqueous alkali hydroxide to form an alkali cellulose. In the second step, the alkali cellulose is contacted with an etherifying agent.

[0070] • Etherifying agents to add alkyl substituents to cellulose include alkyl chlorides. For example, in the production of methyl cellulose, the etherifying agent is methyl chloride. In the production of ethyl cellulose, the etherifying agent is ethyl chloride.

[0071] • Etherifying agents to add hydroxy alkyl substituents to cellulose include alkyl epoxides. For example, in the production of hydroxypropyl cellulose, the etherifying agent is propylene oxide.

[0072] • Mixtures of etherifying agents can produce cellulose ethers with mixed ether substituents, such as ethyl methylcellulose or hydroxypropyl methylcellulose.

[0073] Crosslinked cellulose ethers are also commercially available, such as under the WALOCEL™ M 120-01 trademark. Others can be made by known processes, as previously described.

[0074] In some embodiments, the quantity of cellulose ether in the base coat formulation is at least 0.10 weight percent or at least 0.15 weight percent or at least 0.2 weight percent or at least 0.22 weight percent or at least 0.24 weight percent, based on the weight of dry components and excluding aqueous carrier. In some embodiments, the quantity of cellulose ether in the base coat formulation is at most 1 weight percent or at most 0.5 weight percent or at most 0.4 weight percent or at most 0.3 weight percent, based on the weight of dry components and excluding aqueous carrier.

[0075] In some embodiments, the weight ratio of polymer binder to cellulose ether in the base coat formulation is at least 5: 1 or at least 6: 1 or at least 7: 1 or at least 8:1 or at least 9: 1. In some embodiments, the weight ratio of polymer binder to cellulose ether in the base coat formulation is at most 30: 1 or at most 20: 1 or at most 18: 1 or at most 16:1 or at most 14: 1 or at most 12: 1.

[0076] In addition to cement, filler, pozzolans, inorganic pigments, polymer binder and cellulose ether, some embodiments of the base coat formulation may optionally contain other additives. An exemplary list of additives that may be used in the base coat formulation include the following:

[0077] • Polymeric dispersants reduce agglomeration of solid components in the aqueous composition.

[0078] See, for example, “Dispersants Technology and Benefits” published by Lubrizol Corporation (2018), and US Patent 6,326,449 Bl . Some common polymeric dispersants are polyacrylamides, and their concentration must meet the limits stated in this application.

[0079] • Air-entraining agents cause the formation of small air-bubbles in the dried base coat, which can improve its resilience under freeze-thaw cycles. Air-entrainment agents are frequently surfactants. Suitable air-entrainment additives are commercially available.

[0080] • Accelerators speed the setting of the cement. They may be especially useful in cold-weather applications. Examples of common accelerants include calcium nitrate, calcium nitrite, calcium formate and certain aluminum compounds. Accelerator formulations with instructions for their use are commercially available.

[0081] • Retarders slow the setting time of the cement. Examples of common retarders include calcium, sodium and ammonium salts of lignosulfonic acid, hydroxycarboxylic acids such as hydroxylic acid, carbohydrates, lead oxides, zinc oxides, phosphates, borates and fluorates. Retarder formulations with instructions for their use are commercially available.

[0082] • Defoamers can reduce air-entrainment and voids in the base coat. Examples of defoamers include mineral oils, polyglycols and polyethersiloxanes. Defoamers with instructions for their use are commercially available.

[0083] • Inorganic rheology modifiers, such as bentonite clay, organically-modified clay, attapulgite, fumed silica and precipitated calcium carbonate, can modify the viscosity and shear thinning behavior of the base coat formulation. Suitable inorganic rheology modifiers with instructions for their use are commercially available.

[0084] • Plasticizers and water reducers allow the production and use of aqueous formulations with lower water content. Examples of supcrplasticizcrs include sulfonated mclaminc-formaldchydc condensates, sulfonated naphthalene-formaldehyde condensates, modified lignosulfonates and polycarboxylates. Plasticizer formulations with instructions for their use are commercially available.

[0085] In some embodiments, the base coat formulation contains at most 5 weight percent of the other components or at most 3 weight percent or at most 2 weight percent, based on the dry components in the composition and excluding aqueous carrier. In some embodiments, the dry mix contains no measurable content of the other components (essentially 0 weight percent), based on the weight of dry components in the composition and excluding aqueous carrier.

[0086] Two common components for base coat formulations are excluded or used only sparingly in the base coats of this invention.

[0087] • Starch ethers are polysaccharides modified by an etherifying reaction. Starch ethers are used in coatings and mortars to add viscosity, extend open time and improve surface appearance. Common starch ethers include carboxymethyl starch ether (CMS), hydroxypropyl starch ether (HPS), hydroxyethyl starch ether (HES) and cationic starch ether. Base coat formulations of this invention contain no more than 19 weight percent starch ether, based on the weight of cellulose ether. In some embodiments, the base coat formulation contains no more than 15 weight percent starch ether, based on the weight of cellulose ether, or no more than 12 weight percent or no more than 10 weight percent or no more than 8 weight percent 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 base coat formulation contains no measurable quantity of starch ether (essentially 0 weight percent), based on the weight of cellulose ether. • Polyacrylamides are used in mortars and cementitious coatings to increase viscosity, increase water retention, reduce slump and sagging and improve flexibility. Base coat formulations of this invention contain no more than 1.2 weight percent polyacrylamide, based on the weight of cellulose ether. In some embodiments, the base coat formulation contains no more than 1.0 weight percent polyacrylamide, based on the weight of cellulose ether, or no more than 0.8 weight percent or no more than 0.6 weight percent or no more than 0.4 weight percent or no more than 0.2 weight percent or no more than 0.1 weight percent. In some embodiments, the base coat formulation contains no measurable quantity of polyacrylamide (essentially 0 weight percent, based on the weight of cellulose ether).

[0088] It is also common to add fatty acids (including fatty acid salts) to base coat formulations as hydrophobic admixtures, to reduce the water uptake of the cured base coat. Examples of fatty acids include oleic acid and sodium oleate. However, base coats of this invention have reduced water uptake without added fatty acids, so fatty acid admixtures can be unnecessary. In some embodiments, the base coat formulation and resulting base coat contains no more than 0.1 weight percent fatty acid (including fatty acid salts) or no more than 0.08 weight percent or no more than 0.06 weight percent or no more than 0.04 weight percent or no more than 0.02 weight percent or no more than 0.01 weight percent, based on the solid contents of the base coat formulation and excluding aqueous carrier. In some embodiments, the base coat formulation contains no measurable quantity (0 weight percent) fatty acid.

[0089] Dry components in the base coat formulation are in an aqueous carrier. The aqueous carrier contains primarily (more than 50 weight percent) water. In some embodiments, the aqueous carrier consists essentially of water, containing only ordinary components that are commonly found dissolved in tap water. In some embodiments, the aqueous carrier may further contain a minor amount of a water- miscible cosolvent, such as ethanol, acetic acid, ethylene glycol, ethanolamine or acetone. In some embodiments, the aqueous carrier may contain an acid or base. In some embodiments, the pH of the aqueous carrier before dry components are added is at least 5 or at least 5.5 or at least 6 or at least 6.5 or at least 6.75 or at least 6.9. In some embodiments, the pH of the aqueous carrier before dry components are added is at most 9.8 or at most 8.5 or at most 8 or at most 7.7 or at most 7.5 or at most 7.2. It is known that cement raises the pH of water, and it is known to adjust the pH of an aqueous coating composition in order to achieve a desired viscosity.

[0090] The ratio of aqueous carrier to dry components is selected to provide a desired viscosity for the base coat formulation. In some embodiments, the viscosity of the base coat formulation is selected so that the base coat formulation can be applied smoothly with a trowel to the vertical insulation layer and can dry and harden without observable slump or sagging.

[0091] In some embodiments, the weight ratio of aqueous carrier to solids in the base coat formulation is at least 0.15 or at least 0.18 or at most 0.19 or at most 2.20 or at least 0.21. In some embodiments, the weight ratio of aqueous carrier to solids in the base coat formulation is at most 0.35 or at most 0.32 or at most 0.30 or at most 0.28 or at most 0.26 or at most 0.25. The base coat formulation is made by mixing the dry components (and any desired liquid components) with the aqueous carrier until homogeneous. Any known mixing equipment and technique can be used. In some embodiments, the dry components are added separately to the aqueous carrier. In some embodiments, some or all of the dry components are premixed to form a dry mix before being blended with the aqueous carrier. For example, a dry mix may contain the polymer binder and the cellulose ether, or the cement and the cellulose ether, or the cement and the polymer binder, or the cement and the polymer binder and the cellulose ether.

[0092] In some embodiments, the base coat formulation has a slump (as described in the Test Methods) of at most 170 mm at most 165 mm or at most 160 mm or at most 155 mm or at most 153 mm or at most 152 mm. In some embodiments, the base coat formulation has a slump (as described in the Test Methods) of at least 130 mm or at least 140 mm or at least 145 mm.

[0093] In some embodiments, the base coat formulation retains at least 40% coverage when tested for 15 Minute Open Time according to the Test Methods, or at least 45% coverage or at least 48% coverage or at least 50% coverage or at least 55% coverage or at least 60% coverage. There is no maximum desired coverage in the 15 Minute Open Time test, but in some embodiments. Coverage over 90% or 85%Ais unnecessary.

[0094] The base coat formulation is applied as a base coat layer directly or indirectly to the insulation layer and allowed to dry and harden. In some embodiments, the base coat layer is at least 1 / 8 of an inch (3 mm) or at leastlA inch (6 mm). In some embodiments, the base coat layer is at most Vi inch (13 mm) thick or at most 2 / 5 of an inch ( 10 mm) or at most 1 / 3 inch (8 mm) or at mostlA inch (6 mm). The base coat formulation can be applied onto the insulation layer by known means such as troweling. In some embodiments, the base coat layer is smoothed or textured after it is applied.

[0095] In most embodiments, a reinforcing mesh is embedded into the base coat layer. The mesh is often fiberglass or coated metal, but other fibers may be used such as polyester, polyethylene or other polymer fibers. In most embodiments, the reinforcing mesh is resistant to the alkaline environment found in cementitious base coats. In some embodiments, the reinforcing mesh has a mesh size of at least 3 mm or at least 4 mm. In some embodiments, the reinforcing mesh has a mesh size of at most 7 mm or at most 6 mm or at most 5 mm. In some embodiments, the mesh meets the ETAG 004 standards published by the European Union for EIFS cladding. Fiber meshes for EIFS reinforcement are commercially available, such as under the Boen Products, FiFlexMesh, GripRite and Senergy trademarks. In some embodiments, the fiber mesh includes an adhesive, so that it can be adhered directly to the existing surface and then the base coat formulation can be applied on over and through the mesh. In some embodiments, a layer of base coat is applied to the surface and the mesh is pressed onto the layer of base coat. In some embodiments, a second layer of base coat formulation is then applied on top of the mesh. In some embodiments, the thickness of the base coat formulation and the method of application are sufficient to totally cover the mesh so that it is not visible in the completed base coat. The time needed for the base coat layer to dry varies depending on many factors including the contents of the base coat formulation, the thickness of the base coat layer, and the temperature, humidity and air flow around the base coat while it dries. In some embodiments, when tested according to the Vicat needle test as set out in ASTM C403, the final setting time for the base coat formulation is at most 700 minutes or at most 650 minutes or at most 600 minutes or at most 575 minutes or at most 550 minutes or at most 525 minutes. In some embodiments, when tested according to the Vicat needle test as set out in ASTM C403, the final setting time for the base coat formulation is at least 360 minutes or at least 400 minutes or at least 500 minutes. In some embodiments, similar setting times are achieved when tested according to the ultrasonic procedure set out in the Test Methods.

[0096] In some embodiments, when tested according to the Test Methods, the dried base coat formulation has an adhesion strength to concrete of at least 0.55 N / mm2or at least 0.58 N / mm2or at least 0.60 N / mm2or at least 0.65 N / mm2or at least 0.70 N / mm2or at least 0.75 N / mm2or at least 0.77 N / mm2or at least 0.80 N / mm2. There is no maximum desired adhesion strength to concrete, but in some cases, adhesion strength greater than 1 N / mm2may be unnecessary.

[0097] In some embodiments, when tested according to the Test Methods, the dried base coat formulation has an adhesion strength to expanded polystyrene (EPS) board of at least 0.05 N / mm2or at least 0.07 N / mm2or at least 0.08 N / mm2or at least 0.09 N / mm2or at least 0.10 N / mm2or at least 0.11 N / mm2or at least 0.12 N / mm2. There is no maximum desired adhesion strength to EPS board, but in some cases, adhesion strength greater than 0.20 N / mm2or 0.15 N / mm2may be unnecessary.

[0098] In some embodiments, when tested according to the Test Methods, the fully cured base coat formulation has a 24 hour water uptake of no more than 0.8 kg / m2or 0.78 kg / m2or 0.75 kg / m2or 0.72 kg / m2or 0.70 kg / m2or 0.68 kg / m2. There is no minimum desired water uptake, but in some cases water uptake less than 0.5 kg / m2or 0.6 kg / m2is unnecessary.

[0099] After the base coat layer is dry and hardened to the touch, a finish coat layer is applied directly or indirectly onto the base coat layer and allowed to harden. (Optionally, a primer or other layer may be applied to the base coat layer first.) Finish coats and their application are known and commercially available. See, for example, US Patent Publication US 2014 / 0373474 Al. In some embodiments, the finish coat contains acrylic binder, filler, redispersible powder and other additives such as pigments and weather resistance additives, suspended in an aqueous carrier. The finish coat may be applied by known means such as trowelling, rolling or spraying. The finish coat layer is typically from 1 -25 mm thick.

[0100] The resulting EIFS cladding contains (1) a layer of rigid insulation; (2) a layer of base coat adhered directly or indirectly to the layer of insulation, which optionally contains an embedded mesh reinforcement; and (3) a layer of finish coat adhered directly or indirectly to the layer of base coat. Each layer has the contents and thickness previously described. Test Methods

[0101] Unless stated otherwise, measurements listed in this application are made using the following test methods: Adhesion Strength

[0102] Adhesion strength is tested on two substrates: expanded polystyrene (EPS) panels and concrete panels.

[0103] A 5-mm thick silicone stencil with 50-mm-holes is placed onto the substrate. The base coat formulation is filled into the holes, and the excess scraped off with a spatula. After 24 hours of storage at standard climatic conditions (23 °C / 50 % rel. hum.), the silicone stencil is removed, and panels are stored in standard climate (23 °C ± 2 and 50 % rel. hum. ± 5 at an airflow of < 0.2 m / s) for an additional 11 days to cure.

[0104] After 11 days storage, a pull-off dolly is attached to each cured base coat disc using a two- component epoxy resin (Korapox 558 epoxy resin or equivalent). For EPS panels, a steel circular stencil with 60-mm-holes is placed onto the panel to support the panels during the test and prevent it from breaking. The adhesive discs are pulled off at a force gradient of 50 N / s using a PT Sube Herion HP850 adhesive testing device or an equivalent device such as a DeFelsko ATM50 PosiTest AT-M manual pull- off adhesion tester with 50mm dollies. The required force in kN is read off from the device.

[0105] Quick open time:

[0106] A 200 g sample of freshly mixed wet base coat formulation is applied and combed with a 60° angle using a 6x6 mm notched trowel on a plasterboard. 6 tiles are laid into the base coat formulation bed after 5, 10, 15, 20, 25, and 30 min, respectively, using a 2 kg block (2 kg weight on a 5 cm x 5 cm surface) for 30 s to ensure good transfer of base coat formulation on tiles during installation. After 40 min, all tiles are carefully removed from the base coat formulation bed and flipped over. Base coat formulation coverage of the back of tiles is evaluated with the help of a squared frame. The target is 50 percent or greater coverage.

[0107] Water Absorption:

[0108] A 1.5 mm thick metal pattern is placed on an EPS panel and filled with the base coat formulation, and the excess is scraped off with a spatula. The fiberglass mesh with a density of 160-165 g / m2is applied to the base coat. The 1.5 mm thick metal pattern is removed, and a 3.0 mm thick metal pattern is placed around the existing sample base coat formulation and mesh. A second layer of base coat formulation is added on top of the mesh to fill the mold, and excess is scraped off to leave a 3 mm thick sample of base coat formulation with the mesh at a consistent point in the sample. The metal pattern is removed. The EPS panel is stored for 27 days under standard climatic conditions (23 °C ± 2 and 50 % reL hum. ± 5 at an airflow of < 0.2 m / s) to cure. The edges of the panel are cut to the cured base coat layer. The weight of each test specimen is determined. The specimens are placed with the base coat layer down in a water bath (23 ± 2 °C). After 24 hours, the test samples are removed, excess water is wiped off and the weight of each specimen is determined. The difference in weight is the water absorption.

[0109] Examples

[0110] The following examples illustrate specific embodiments of the invention, but do not limit the broadest scope of the invention.

[0111] The materials in Table 1 are used for the Examples:

[0112] Table 1 (All viscosities 2% in water, measured with Haake Rotovisko viscometer at 20°C)

[0113] (TDCC = The Dow Chemical Company)

[0114] The materials listed in Table 1 are mixed to make the base coat formulations in the proportions set out in Table 2. Examples IE1 to IE5 are examples of the invention. Examples CE1 to CE5 are comparative. The quantity of water is selected to provide a base coat formulation that is fully wetted and workable and has a slump from 145 mm to 155 mm. The dry components are added to the water and then mixed according to the following profile: • Mix 30 seconds at 140 RPM (all RPM are ± 5 RPM);

[0115] • Rest 1 minute

[0116] • Mix 1 minute at 140 RPM;

[0117] • Rest 5 minutes; and • Mix 15 seconds at 140 RPM.

[0118] Each base coat formulation is tested for slump, adhesion to concrete and EPS panels, 24 hour water uptake, Quick Open time, and setting time, according to the Test Methods. Results are shown in Table 2.

[0119] The materials listed in Table 1 are mixed as in the previous examples to make the base coat formulations in the proportions set out in Table 3. Examples IE6 to IE11 are examples of the invention. Examples CE6 to CE7 are comparative. Each base coat formulation is tested for slump and 24 hour water uptake, according to the Test Methods. Results are shown in Table 3. The results show that inventive formulations have low water-pickup, regardless of whether they contain sodium oleate or not. On the other hand, comparative examples have high water uptake without sodium oleate.

[0120]

[0121]

Claims

CLA1MS:

1. A process to make an EIFS cladding, which process comprises the steps of: (1) adhering a layer of rigid insulation to the exterior wall of a building; (2) applying a layer of base coat formulation and optionally a reinforcing mesh directly or indirectly to the layer of rigid insulation, and allowing the base coat formulation to dry; and (3) applying a layer of finish coat formulation directly or indirectly to the layer of base coat, and allowing the finish coat formulation to dry, wherein the base coat formulation comprises the following dry components in an aqueous carrier:(a) cement;(b) filler;(c) at least 1% by weight of a polymer binder;(d) at least 0.1% by weight of a cellulose ether with a viscosity of at least 30,000 cP, at 20°C and 2% concentration in water; and(e) from 0 to 19 weight percent starch ether and from 0 to 1.2 weight percent polyacrylamide, based on the weight of cellulose ether, wherein weight percentages are based on the weight of dry components and excluding aqueous carrier, unless otherwise stated.

2. The process of Claim 1 wherein the polymer binder in the base coat formulation has a glass transition temperature from -5°C to 25°C.

3. The process of Claim 2 wherein the polymer binder in the base coat formulation comprises a vinyl ester copolymer or an acrylic copolymer.

4. The process of Claim 3 wherein the weight ratio of cement to polymer binder is from 7: 1 to 20: 1.

5. The process of Claim 1 wherein the cellulose ether in the base coat formulation is a crosslinked cellulose ether.

6. The process of Claim 5 wherein the cellulose ether in the base coat formulation has a viscosity of at least 50,000 cP, at 20°C and 2% concentration in water.

7. The process of Claim 5 wherein the cellulose ether in the base coat formulation has a crossover value of from 1.5 rad / s to 8 rad / s in a 1% solution in water at 20°C.

8. The process of Claim 5 wherein the quantity of cellulose ether in the base coat formulation is from 0.15 weight percent to 0.5 weight percent, based on the weight of dry components and excluding aqueous carrier.

9. The process of Claim 5 wherein the weight ratio of polymer binder to cellulose ether in the base coat formulation is from 9: 1 to 12: 1.

10. The process of Claim 1 wherein the base coat formulation contains no more than 10 weight percent starch ether, based on the weight of cellulose ether.

11. The process of Claim 1 wherein the base coat formulation contains no more than 0.6 weight percent polyacrylamide, based on the weight of cellulose ether.

12. The process of Claim 1 wherein the base coat formulation is used as an adhesive to adhere the layer of rigid insulation to the exterior wall of the building.

13. The process of Claim 1 wherein:(a) the polymer binder in the base coat formulation comprises a vinyl ester copolymer or an acrylic copolymer with a glass-transition temperature from -5°C to 25°C, and the weight ratio of cement to polymer binder is from 7: 1 to 20: 1 ; and(b) the cellulose ether is a crosslinked cellulose ether having a viscosity of at least 50,000 cP, at 20°C and 2% concentration in water, and the weight ratio of polymer binder to cellulose ether in the base coat formulation is from 7: 1 to 16: 1 ; and(c) the base coat formulation contains no more than 10 weight percent starch ether, based on the weight of cellulose ether; and(d) the base coat formulation contains no more than 0.6 weight percent polyacrylamide, based on the weight of cellulose ether.

14. The process of any one of Claims 1 through 13 wherein the base coat formulation contains no more than 0.08 weight percent fatty acid or fatty acid salt, based on the weight of dry components and excluding aqueous carrier.

15. An EIFS cladding that contains (1) a layer of rigid insulation; (2) a layer of base coat adhered directly or indirectly to the layer of insulation, which optionally contains an embedded reinforcing mesh; and (3) a layer of finish coat adhered directly or indirectly to the layer of base coat, wherein the layer of base coat comprises:(a) cement;(b) filler; and(c) at least 1% by weight of a polymer binder;(d) at least 0.1% by weight of a cellulose ether with a viscosity of at least 30,000 cP, at 20°C and 2% concentration in water; and(e) from 0 to 19 weight percent starch ether and from 0 to 1.2 weight percent polyacrylamide, based on the weight of cellulose ether.

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