Water-resistant waterborne acrylic coating materials, systems and methods providing enhanced water resistance and durability are provided. Such coatings extend the service life of roofing systems that are exposed to ponding water and other extreme weather conditions. Coatings described herein exhibit superior water resistance attributes including one or more of water infiltration resistance, wet tensile strength and wet adhesion.

BACKGROUND

Among the most significant properties of commercial and residential roofing systems is water resistance. The durability and service life of roofing systems largely depends upon its ability to prevent water infiltration and to provide sustained mechanical properties, such as wet tensile strength and wet adhesion, in applicable environmental conditions. Ponding is the occurrence of water pooling on flat roofs or localized flat roofing sections from exposure to storms, snow melts, heavy rains or other wet conditions. Generally, conventional roof systems are simply not designed to hold water for prolonged durations. Ponding water can collect dirt, which may cause the growth of vegetation and biofilm or telegraph mud cracking and chipping. It can also act as a magnifying glass on the roof under the pond, thus possibly increasing ultraviolet exposure and causing localized damage. It can also contribute to photo-oxidation and resultant premature deterioration of the roof membrane, flashings and coatings. Ultimately, these and other effects can lead to structural damage and possible roof collapse.

Waterborne roof coatings, most notably acrylic coatings, are commonly used to extend roof service life. Acrylic coatings are eco-friendly and exhibit a combination of benefits including high reflectivity, re-coatability, good adhesion to multiple substrates and desirable mechanical properties. Failures of known acrylic coatings may include micro-cracking, delamination or de-bonding, and biofilm attachment, which can lead to cracking, chipping, etc., and ultimately to structural damage of the underlying roof structure. One of the advantages of the coating materials, systems and methods provided herein is to address these known failures by providing acrylic coating systems that are resistant to ponding water failures while retaining the benefits of waterborne coatings.

SUMMARY

Described herein are water-resistant waterborne acrylic coating materials, systems and methods providing enhanced water resistance and durability. Such coatings extend the service life of roofing systems that are exposed to ponding water and other extreme weather conditions. Coatings described herein exhibit superior water resistance attributes including one or more of water infiltration resistance, wet tensile strength and wet adhesion. Resultant coatings are resistant to ponding water failures upon long-term exposure to standing water environment, wet-dry cycling and other thermal cycle stresses.

In one aspect, a coating material is provided, which is suitable for application to a roofing substrate, among other uses. In certain embodiments, the coating material comprises at least one acrylic latex resin, at least one functional filler, and at least one hydrophobic additive.

In certain embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a water infiltration depth of about 120 microns or less after 4 hours at 60° C. and 95% relative humidity.

In certain embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet tensile strength of at least about 80 psi as measured according to ASTM D882 and/or ASTM D2370. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet tensile strength of about 80 psi to about 500 psi as measured according to ASTM D882 and/or ASTM D2370. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet tensile strength of about 85 psi to about 500 psi as measured according to ASTM D882 and/or ASTM D2370. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet tensile strength of about 90 psi to about 500 psi as measured according to ASTM D882 and/or ASTM D2370. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet tensile strength of about 95 to about 500 psi as measured according to ASTM D882 and/or ASTM D2370.

In certain embodiments, the acrylic latex resin is selected from the group consisting of hydrophobic resins, self-crosslinking resins, and crosslinkable resins.

In certain embodiments, the content of the at least one acrylic latex resin within the coating material is about 20-70 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 30-70 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 40-70 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 50-70 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 20-60 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 20-50 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 20-40 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 20-30 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 25-65 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 30-60 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 35-55 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 35-50 weight percent.

In certain embodiments, the content of at least one functional filler within the coating material is about 10-50 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 10-40 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 10-30 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 10-20 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 20-50 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 30-50 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 40-50 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 15-45 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 20-45 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 25-45 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 30-45 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 35-40 weight percent.

In certain embodiments, the functional filler is selected from the group consisting of silicate minerals, silica, wollastonite (calcium inosilicate mineral CaSiO3), talc, mica, kaolin, feldspar, nepheline syenite, nanoclays, platy fillers, nano-oxide materials, calcium carbonate, aluminum hydroxide, magnesium hydroxide, aluminum tryhydrate, basalt, zinc oxide, barium sulfate, and combinations thereof. In certain embodiments, the functional filler is characterized by a high aspect ratio, which can enhance tensile strength of the coating material while retaining water infiltration resistance and wet adhesion. In embodiments, the aspect ratio of the functional filler is about 3-100. In embodiments, the aspect ratio of the functional filler is about 5-100. In embodiments, the aspect ratio of the functional filler is about 10-100. In embodiments, the aspect ratio of the functional filler is about 15-100. In embodiments, the aspect ratio of the functional filler is about 20-100. In embodiments, the aspect ratio of the functional filler is about 25-100. In embodiments, the aspect ratio of the functional filler is about 30-100. In embodiments, the aspect ratio of the functional filler is about 35-100. In embodiments, the aspect ratio of the functional filler is about 40-100. In embodiments, the aspect ratio of the functional filler is about 45-100. In embodiments, the aspect ratio of the functional filler is about 50-100. In embodiments, the aspect ratio of the functional filler is about 55-100. In embodiments, the aspect ratio of the functional filler is about 60-100. In embodiments, the aspect ratio of the functional filler is about 65-100. In embodiments, the aspect ratio of the functional filler is about 70-100. In embodiments, the aspect ratio of the functional filler is about 75-100. In embodiments, the aspect ratio of the functional filler is about 80-100. In embodiments, the aspect ratio of the functional filler is about 85-100. In embodiments, the aspect ratio of the functional filler is about 90-100. In embodiments, the aspect ratio of the functional filler is about 95-100. In embodiments, the functional filler is a high aspect ratio filler comprising wollastonite, talc, clays and/or mica. The inventors have found that when embodiments of the coating material containing one or more functional fillers having an aspect ratio of about 3-100 are applied as a 500 micron dry film thickness coating to a roofing substrate, the coating exhibits a greater dry tensile strength than a test coating on a roofing substrate applied with an identical coating material without the one or more functional fillers having an aspect ratio of about 3-100.

In certain embodiments, the content of at least one hydrophobic additive is about 0.5-20 weight percent. In other embodiments, the content of at least one hydrophobic additive is about 0.5-10 weight percent. In other embodiments, the content of at least one hydrophobic additive is about 1-5 weight percent. In other embodiments, the content of at least one hydrophobic additive is about 1-3 weight percent. In other embodiments, the content of at least one hydrophobic additive is about 1-2 weight percent.

In certain embodiments, the hydrophobic additive is selected from the group consisting of hydrophobic copolymer dispersants and salts thereof, nonionic rheology modifiers, PTFE powders, silicone surface additive, polyolefin powder with having molecular weight within the range 100,000-1,000,000 Daltons, polyolefin wax and hydrophobic wax dispersions.

In certain embodiments, coating material further comprises a crosslinking agent. In another aspect, a coating system is provided that comprises a roofing substrate and a coating material at least partially coating the roofing substrate, wherein the coating material comprises at least one acrylic latex resin, at least one functional filler, and at least one hydrophobic additive. The roofing substrate comprises any suitable material or structure used in commercial or residential roofing applications, including underlayment and flashing.

In yet another aspect, a coating method is provided that comprises the application of a coating material to a roofing substrate, where the coating material comprises at least one acrylic latex resin, at least one functional filler, and at least one hydrophobic additive.

DETAILED DESCRIPTION

The coating materials provided herein generally comprise at least one acrylic latex resin, at least one functional filler, and at least one hydrophobic additive. The inventors have found that such materials exhibit superior water resistance properties, including preventing water infiltration while providing high wet tensile strength and wet adhesion, thus providing durable roofing systems even under ponding conditions when applied to roofing substrates.

The functional fillers used in embodiments described herein provide enhanced properties such as tensile, water resistance and adhesion properties. Examples of such fillers include silicate minerals, silica, wollastonite, talc, mica, kaolin, feldspar, and nepheline syenite, surface treated fillers and sub-micron fillers such as nanoclays, platy fillers and nano-oxides commonly used in anti-corrosion coatings. Without wishing to be bound by theory, the inventors believe that the incorporation of the nano-fillers creates a tortuous pathway for water permeation, limiting water absorption and adverse solvation effect on the coating. Examples of surface treated fillers include calcium carbonates, Camel-Wite™ ST (Imerys), aluminum trihydrate (low solubility) such as Hymod® (J.M. Huber Corporation) Micral grades, and Hymod M9400 SG & Hymod SB432-SG-surface treated grade. Other functional fillers are hydrophobic in nature and include Novakup® and Novacite® (Malvern Minerals Company) platy silica, treated and non-treated fumed silicas, Aerosil® (Evonik Degussa GmbH), Oxylink™ (Micronisers Australasia Pty Ltd.), pre-dispersed nano ZnO2, and nano-kaolin, -bentonite, and -monomonilorite clays.

In certain embodiments, the content of the at least one acrylic latex resin within the coating material is about 20-70 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 30-70 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 40-70 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 50-70 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 20-60 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 20-50 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 20-40 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 20-30 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 25-65 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 30-60 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 35-55 weight percent. In other embodiments, the content of the at least one acrylic latex resin within the coating material is about 35-50 weight percent.

In certain embodiments, the content of at least one functional filler within the coating material is about 10-50 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 10-40 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 10-30 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 10-20 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 20-50 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 30-50 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 40-50 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 15-45 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 20-45 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 25-45 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 30-45 weight percent. In other embodiments, the content of at least one functional filler within the coating material is about 35-40 weight percent.

In certain embodiments, the content of at least one hydrophobic additive is about 0.5-20 weight percent. In other embodiments, the content of at least one hydrophobic additive is about 0.5-10 weight percent. In other embodiments, the content of at least one hydrophobic additive is about 1-5 weight percent. In other embodiments, the content of at least one hydrophobic additive is about 1-3 weight percent. In other embodiments, the content of at least one hydrophobic additive is about 1-2 weight percent.

The coating materials provided herein optionally comprise pigment materials such as titanium dioxide particles. In certain of these embodiments, the content of the pigment is 2-15 weight percent. In other embodiments, the content of the pigment is 3-15 weight percent. In other embodiments, the content of the pigment is 4-15 weight percent. In other embodiments, the content of the pigment is 5-15 weight percent. In other embodiments, the content of the pigment is 6-15 weight percent. In other embodiments, the content of the pigment is 7-15 weight percent. In other embodiments, the content of the pigment is 8-15 weight percent. In other embodiments, the content of the pigment is 9-15 weight percent. In other embodiments, the content of the pigment is 10-15 weight percent. In other embodiments, the content of the pigment is 11-15 weight percent. In other embodiments, the content of the pigment is 12-15 weight percent. In other embodiments, the content of the pigment is 13-15 weight percent. In other embodiments, the content of the pigment is 14-15 weight percent. In other embodiments, the content of the pigment is 2-14 weight percent. In other embodiments, the content of the pigment is 2-13 weight percent. In other embodiments, the content of the pigment is 2-12 weight percent. In other embodiments, the content of the pigment is 2-11 weight percent. In other embodiments, the content of the pigment is 2-10 weight percent. In other embodiments, the content of the pigment is 2-9 weight percent. In other embodiments, the content of the pigment is 2-8 weight percent. In other embodiments, the content of the pigment is 2-7 weight percent. In other embodiments, the content of the pigment is 2-6 weight percent. In other embodiments, the content of the pigment is 2-5 weight percent. In other embodiments, the content of the pigment is 2-4 weight percent. In other embodiments, the content of the pigment is 2-3 weight percent.

In some embodiments, the coating material has a wet tensile strength of at least about 80 psi as measured according to ASTM D882 and/or ASTM D2370.

Coatings made from the coating materials described herein provide excellent resistance against water infiltration. In some embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a water infiltration depth after 4 hours at 60° C. and 95% relative humidity of about 120 microns or less in some embodiment, about 100 microns or less in other embodiments, about 75 microns or less in other embodiments, about 55 microns or less in other embodiments, and about 35 microns or less in other embodiments. When the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet tensile strength as measured according to ASTM D882 and/or ASTM D2370 of at least about 80 psi in some embodiments, at least 95 psi in other embodiments, and at least 105 psi in other embodiments, at least 120 psi in other embodiments, and at least 130 psi in other embodiments. When the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of at least about 2 pli (pounds per linear inch) as measured according to ASTM D903 in some embodiments. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 2 pli to about 15 pli as measured according to ASTM D903. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 3 pli to about 15 pli as measured according to ASTM D903. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 4 pli to about 15 pli as measured according to ASTM D903. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 5 pli to about 15 pli as measured according to ASTM D903. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 6 pli to about 15 pli as measured according to ASTM D903. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 7 pli to about 15 pli as measured according to ASTM D903. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 8 pli to about 15 pli as measured according to ASTM D903. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 9 pli to about 15 pli as measured according to ASTM D903. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 10 pli to about 15 pli as measured according to ASTM D903. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 11 pli to about 15 pli as measured according to ASTM D903. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 12 pli to about 15 pli as measured according to ASTM D903. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 13 pli to about 15 pli as measured according to ASTM D903. In embodiments, when the coating material is applied as a coating to the roofing substrate, the coating exhibits a wet adhesion of about 14 pli to about 15 pli as measured according TO ASTM D903.

EXAMPLES

Embodiments of the invention are described with reference to the following non-limiting examples. Samples 1-12 were formulated and tested for various mechanical properties as described herein.

Coating formulations were prepared as follows. The grind stage was prepared by adding the water, dispersing agent and wetting agent together and combining. The fillers were then added in stages with short 30 second cycles at 1200 rpm in a counter-rotating planetary speed mixer. The pigment (TiO2) and pigment extender were added together and mixed. The calcium carbonate was then added in two stages. Finally, defoamer and any thickener were added with light stirring and speed mixed for 45 seconds. Once checked for homogeneity, the grind stage was mixed at 1600 rpm for 3 minutes to ensure full dispersion. The letdown stage was performed in a standard high-speed disperser with a Cowles style blade, and each addition was done in rank order shown to incorporate fully before the next addition. Alternatively, similar results were attained by thoroughly hand-stirring each additive into the batch with a spatula and performing a final speed mix of 1 minute at 1200 rpm. Batches were allowed to sit overnight at ambient temperatures in their sealed containers. All batches were speed mixed at 1200 rpm for 1 minute under 26 in Hg of vacuum to de-air the coating before films were drawn down.

Wet tensile testing was performed according to ASTM D882 and/or ASTM D2370 after 24 hours at 72° F. immersion in water. All samples were cut using a six cell die of sample dimensions 0.5″×3″. Samples were handled and measured while wet, and blotted dry just before testing.

Water infiltration testing was performed on 2″ diameter samples of a 500 micron dry film thickness (dft) coating film placed on a 2″ outer diameter Quick-Clamp Sanitary Tube Fitting placed on top of a metal mesh set in a sample tray to allow for air flow to bottom of membrane. About 20 ml of 1% Methylene Blue solution was pipetted into the top section of the fitting. Each sample on its tray was then placed into a stability chamber set to 60° C. at 95% relative humidity for 4 hours. The sample jig was then drained of dye solution, blotted dry and the samples were removed and allowed to cool and dry. Each sample was cut evenly in half with a clean sharp razor blade. Samples were mounted into a micro vise edge up and cross sections were viewed at 200× magnification. The total film thickness and average depth of dye penetration were measured optically and recorded.

For wet adhesion testing, samples were prepared by creating a total of 500 micron dry film thickness (dft) film with an embedment of a reinforcement in size, 5 inches wide and 11 inches long. Samples were drawn down on a 6 inch-by-6 inch sample of 45 mil TPO with TPO Red Primer (GAF Materials Corporation). Silicone caulk was used to seal all edges to prevent lateral water infiltration. The cured samples were placed in pans filled with 1-1.5 inches of deionized water and allowed to rest either at room temperature or at 60° C. for 7 days. The water in the pan was then drained and the samples were tested as per ASTM D903.

Table I provides compositional information for Samples 1-12, and Table II provides test results.

TABLE IISample properties (note that Sample numberscorrespond with the compositions shown in Table I).Dry tensileWet tensileWater60° C. Wetstrengthstrengthinfiltrationadhesion,Sample #(psi)(psi)(microns)pli1184561587.5(comparative)715821388n/a(comparative)918188413.6(comparative)11185108723.4(comparative)2196921187.4318097544.6426087442.6532795286.662468520281927071n/a1024793402.812251130663.7

Several observations can be drawn from inspection of Tables I and II. Samples 2 and 3 illustrate the improvement to water infiltration resistance and wet tensile strength compared with Comparative Sample 1. The improvements are believed to result from the use of hydrophobic additives. Samples 5 and 6 illustrate further improvements to the wet tensile strength and/or water infiltration properties of Sample 4, which is based upon a hydrophobic acrylic with high water infiltration resistance. Sample 5 makes use of Camel White™ ST (Imerys), a fine particle size, wet ground white calcitic marble. Sample 6 contains 15 wt % CaraPol AAR-127 as an additional hydrophobic additive. Sample 8 shows a significant improvement over Comparative Sample 7 in wet tensile strength and water infiltration resistance from the addition of nanofiller Oxylink as a functional filler, and crosslinking agent Carbodilite E-05. Sample 10 contains a blend of calcium carbonate and 3.7% wollastonite filler and shows a 36% increase in dry tensile strength relative to the comparative example 9 with only calcium carbonate. Sample 12 contains a blend of hydrophobically modified ATH and 7.3% wollastonite and shows a 36% increase in dry tensile strength and a 20% increase in wet tensile strength relative to the comparative example 11 with only hydrophobically modified ATH.

Conventional terms in the fields of materials science and engineering have been used herein. The terms are known in the art and are provided only as a non-limiting example for convenience purposes. Accordingly, the interpretation of the corresponding terms in the claims, unless stated otherwise, is not limited to any particular definition. Thus, the terms used in the claims should be given their broadest reasonable interpretation.

The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to comply with 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.