WO2019060492A1 - Coating compositions comprising hollow glass microspheres and films therefrom - Google Patents

Abstract

Described herein is a coating composition and films therefrom, wherein the coating composition comprises a plurality of hollow glass microspheres wherein the plurality of hollow glass microspheres comprises, on an equivalent weight basis more than 0.5% of Al2O3; and at least one film-forming polymer.

Description

COATING COMPOSITIONS COMPRISING HOLLOW GLASS MICROSPHERES AND

FILMS THEREFROM

TECHNICAL FIELD

[0001] A coating composition comprising a film-forming polymer and a plurality of hollow glass microspheres is described along with films made therefrom.

SUMMARY

[0002] There is a desire to identify ways to balance performance characteristics (such as durability and appearance) of coating compositions and/or films. There is also a desire to decrease the cost of coating compositions and/or resulting films.

[0003] In one aspect, a coating composition is described comprising a plurality of hollow glass microspheres wherein the plurality of hollow glass microspheres comprises, on an equivalent weight basis, more than 0.5% of AI₂O3; and at least one film-forming polymer.

[0004] In another aspect, a coating composition is described comprising a film forming polymer and a plurality of hollow glass microspheres, wherein the plurality of hollow glass microspheres comprise, on an equivalent weight basis, from 50-75 % of silica, 8-15 % calcium oxide; greater than 2 % of boria, 0.5-5 % of phosphorous pentoxide; 0.5-5 % of zinc oxide; greater than 1 % of alumina; and 0-7% of sodium oxide.

[0005] The above summary is not intended to describe each embodiment. The details of one or more embodiments of the invention are also set forth in the description below. Other features, objects, and advantages will be apparent from the description and from the claims.

DETAILED DESCRIPTION

[0006] As used herein, the term

"a", "an", and "the" are used interchangeably and mean one or more;

"and/or" is used to indicate one or both stated cases may occur, for example A and/or B includes, (A and B) and (A or B);

"d5o" refers to that particle diameter at which 50 percent by volume of the particles in a distribution of particles have that diameter or a smaller diameter. For the purposes of the present disclosure, the particle diameter is determined by laser light diffraction by dispersing the hollow glass microspheres in deaerated, deionized water. Laser light diffraction particle size analyzers are available, for example, a Model S3500 Particle Size Analyzer obtained from Nikkiso America, San Diego, CA.; "CI90" refers to that particle diameter at which 90 percent by volume of the particles in a distribution of particles have that diameter or a smaller diameter as determined by laser light diffraction;

"equivalent basis" in reference to an elemental oxide refers to the total amount of atoms included in the specified elemental oxide contained in a specified original composition, regardless of their actual arrangement in the specified original composition. For example, one mole of spinel (i.e., MgAl204), a mixed oxide of magnesium and aluminum may be considered to contain, on an equivalent basis, one mole each of MgO and AI2O3. Likewise, one mole of aluminum phosphate

(i.e., AIPO4) contains half a mole each of AI2O3 and P2O5.

[0007] Also herein, recitation of ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0008] Also herein, recitation of "at least one" includes all numbers of one and greater (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).

[0009] Water-based architectural paints are comprised of many ingredients each having a specific effect on the paint prior to, during, and/or after application. Environmental regulations, material cost, and the properties of the paint can all factor into determining the final formulation. For example, environmental regulations have dictated decreasing levels of volatile organic compounds (VOC's) in coatings. One of the main reasons for VOC's in coatings is to serve as coalescents, which plasticize the film-forming polymer allowing it to form a continuous film as the paint dries. With lower amounts of VOC's or even no VOC's, film-forming polymers with lower glass transition temperatures (Tg) that coalesce more easily have been used. These lower Tg polymers are more expensive and do not generate a hard film as compared to coatings comprising traditional film-forming polymers plasticized with VOC's.

[0010] Solid ceramic microspheres have found application in these new low-VOC paint formulations for their ability to maintain scrub and burnish properties at higher pigment volume concentration.

[0011] In many industries, hollow glass microspheres (e.g., hollow glass microspheres also commonly known as "glass microbubbles", "glass bubbles ", "hollow glass beads", or "glass balloons") are useful as additives for polymeric formulations. These hollow glass microspheres, when added to polymeric compositions can, for example, lower weight and improve processing, and provide dimensional stability. Due to their scattering ability, hollow glass microspheres are of interest for use in architectural paints to opacify the formulation, allowing for example, one-pass application and/or reducing the amount of more expensive opacifying agents, such as titanium dioxide. [0012] The present disclosure relates to the use of hollow glass microspheres in coating compositions. It has been discovered that when hollow glass microspheres are added to coating compositions such as architectural paints, the coating compositions may increase in viscosity over time. In the present disclosure, it has been discovered that when the hollow glass microsphere comprises a particular composition, this viscosity increase may be minimized or even eliminated.

[0013] Microspheres of the present disclosure are glass meaning they are amorphous and have substantially no crystallinity. Hollow glass microspheres according to the present disclosure have a hollow core and are substantially single cell structures. The term "substantially" as used herein means that the majority of the hollow glass microspheres according to the present disclosure have single cell structures. The term "single cell structure" as used herein means that each glass microsphere is defined by only one outer wall with no additional exterior walls, partial spheres, concentric spheres, or the like present in each individual glass microbubble.

[0014] Traditionally, hollow glass microspheres are made by combining glass forming materials along with a blowing agent to form a frit. The frit is then milled to a fine, consistent size range, forming a feed and the feed is heated through a flame, thereby causing expansion and formation of the glass bubbles. Effective blowing agents include sulfur oxides such as, for example, sulfates (such as metal sulfates) and sulfites, which may be used with other blowing agents, such as CO2,

O2, or N2. In order to incorporate the blowing agent into the frit composition and process the frit, various metal oxides and/or metal carbonates are added. For example, sodium carbonate is used as a processing aid for the manufacture of hollow glass microspheres. However, sodium can weaken the glass, thus, other metals such as calcium oxide, boria, phosphorous pentoxide, zinc oxide, and aluminum oxide are added to improve the bubble forming ability, strength and/or stability of the glass. Typically, there is a balance between achieving the performance and processing characteristics, while trying to maintain a high amount of silica.

[0015] The hollow glass microspheres of the present disclosure comprise an equivalent weight basis greater than 0.5, 1, 2, 3, 5 or even 10 percent of alumina (i.e., AI2O3); and no more than 25,

20, or even 15 percent. If the alumina content is too low, hollow glass microsphere may not prevent and/or minimize viscosity increases of a coating composition. If the alumina content is too high, there is difficulty in manufacturing the hollow glass microspheres.

[0016] In one embodiment, the hollow glass microspheres of the present disclosure, further comprises zinc oxide (i.e., ZnO). Like alumina, zinc oxide can stabilize the glass. In one embodiment, the hollow glass microspheres of the present disclosure comprise an equivalent weight basis greater than 0.5, 1, 2, 3, or even 4 percent zinc oxide; and no more than 5, 7 or even 10 percent. [0017] In some embodiments, the hollow glass microspheres may further comprise additional materials such as, for example, MgO, BaO, SrO, PbO, Ti0₂, Mn0₂, Zr0₂, Fe₂0₃, Sb₂0₃, V₂0₅.

Such additional materials may be added to comprise an equivalent weight basis greater than 0.5, 1, 2, 3, or even 4 percent zinc oxide; and no more than 5, 7 or even 10 percent.

[0018] In one embodiment, the hollow glass microspheres according to the present disclosure may comprise, on an equivalent weight basis based on the total weight of the hollow glass microspheres: from 50 to 75 percent (e.g., from 60 to 72 percent) of silica; from 2 to 10 percent (e.g., from 3 to 6 percent, or from 3 to 5 percent) of boria; from 0.5 to 5 percent (e.g., from 1 to 4 percent, or from 1.5 to 3.5 percent) of zinc oxide; from 8 to 15 percent (e.g., from 10 to 15 percent, or from 11 to 13 percent) of calcia; from 0.5 to 5 percent (e.g., from 1 to 5 percent, from 1.4 to 3 percent) of phosphorus pentoxide; from 0 to 7 percent (e.g., from 0.5 to 7 percent, or from 0.5 to 5 percent) of sodium oxide; and greater than 0.5 percent (e.g., from 0.5 to 15 percent, 1.0 to 15 percent, or from 2.0 to 10 percent) of alumina (i.e., A1₂C>3). Optionally, hollow glass microspheres according to the present disclosure further comprise, on an equivalent weight basis, greater than 0.2 percent (e.g., from 0.6 to 1.5 percent, or from 0.7 to 1.2 percent, or from 0.8 to 1.1 percent) of sulfur trioxide (i.e., SO3).

[0019] In one embodiment, the hollow glass microspheres according to the present disclosure need not comprise titanium or zirconium, which in the case of titania may tend to increase cost and in the case of zirconia may increase density and/or cost. Accordingly, the glass microbubbles may be free of zirconia and/or titania. In other embodiments, the glass microbubbles may comprise, on an equivalent weight basis based on the total weight of the hollow glass microspheres, less than 5 weight percent, less than 2 weight percent, less than 1 weight percent, less than 0.5 weight percent, less than 0.2 weight percent, less than 0.1 weight percent, or even less than 0.01 weight percent of titania, zirconia, and/or titania and zirconia combined.

[0020] Although not wanting to be limited by theory, it is believed that less network modifiers in the glass will improve the glass chemical stability. In silicate glass, network modifiers, such as sodium ions, break the silica network and create non bridging oxygen atoms, which can reduce the glass chemical stability. When aluminum oxide is introduced into the glass, the aluminum ion forms, not only a stronger bond than a sodium ion, but there are also more bonds per aluminum atom versus a sodium atom, helping to stabilize the glass. In a coating composition, such as architectural paint, which is a basic solution, the aluminum ion at the glass surface is not Al³⁺, but AIO2^"1, which has a much lower ion leaching rate. Thus, the glass with aluminum oxide can show a significant improvement in chemical stability. [0021] In one embodiment, the hollow glass microspheres comprise a reduced amount of network modifiers. Such network modifiers are known in the art to disrupt the silicate network. Exemplary network modifiers include B₂0₃, CaO, Fe₂0₃, K₂0, MgO, Na₂0, P₂0₅, S0₃, Ti0₂, and ZnO. As shown in the Example Section, there appears to be a relationship between the stability of the coating composition and the ratio of A1₂0₃ to other inorganic oxides present in the hollow glass microspheres. For example, the ratio of A1₂0₃ versus the sum of B₂0₃, CaO, Fe₂0₃, K₂0, MgO, Na₂0, P₂05, S0₃, Ti0₂, and ZnO. In one embodiment of the present disclosure, the ratio of A1₂0₃ versus the sum all other inorganic oxides present with the exception of Si0₂, is greater than 0.01, 0.03, or even 0.05. Although not wanting to be limited by theory, it is believed that elements such as alkali and alkaline earth metals and optionally other elements such as S, Ti and Zn, disrupt the silicate network, leading to the decreased stability of the silicate network. In one embodiment, the addition of ZnO may show an improvement of the silicate glass chemical stability because, like A1₂0₃, zinc ions on the glass surface will form either HZn0₂ ^" or Zn0₂ ^"2, not Zn²⁺.

[0022] In one embodiment, the hollow glass microspheres of the present disclosure have an average true density in a range from at least 0.7, 0.8, 0.85, or even 0.9 grams per cubic centimeter (g/cc); and at most 1.2, 1.5, 1.75, 2, or even 2.4 g/cc, determined according to the method described below. The "average true density" of hollow glass microspheres is the quotient obtained by dividing the mass of a sample of hollow glass microspheres by the volume of that mass of hollow glass microspheres as measured by a gas pycnometer. For the purposes of this disclosure, average true density is measured using a pycnometer following a similar method as disclosed in ASTM D2840- 69, "Average True Particle Density of Hollow Microspheres". The pycnometer may be obtained, for example, under the trade designation "ACCUPYC 1330 PYCNOMETER" from Micromeritics, Norcross, Georgia, or under the trade designations "PENTAPYCNOMETER" or "ULTRAPYCNOMETER 1000" from Formanex, Inc., San Diego, CA. Average true density can typically be measured with an accuracy of 0.001 g/cc. Accordingly, each of the density values provided above can be ± five percent.

[0023] The hollow glass microspheres useful for practicing the present disclosure generally are those that are able to survive (i.e., not crushed during) the grinding process and/or the capillary forces present during coalescence to form the film. A useful isostatic pressure at which ten percent (or less) by volume of hollow glass microspheres collapses (also referred to as strength at 90% survival) is typically greater than about 100, 150, 200, or even 250 MPa. For the purposes of the present disclosure, the collapse strength of the hollow glass microspheres is measured on a dispersion of the hollow glass microspheres in glycerol as described in the Strength Test Method disclosed below. [0024] The hollow glass microspheres of the present disclosure have a high strength to density ratio. In one embodiment, the hollow glass microspheres of the present disclosure have a ratio of strength at 90% survival to density of at least 120, 150, 200, 250, 300, or even 350 MPa per (gram/cubic centimeter).

[0025] In one embodiment, the hollow glass microspheres useful in the present disclosure may be opaque.

[0026] The hollow glass microspheres of the present disclosure are spherical in nature, meaning that hollow glass microspheres have curved edges and or shapes, in one embodiment, the plurality of hollow glass microspheres are substantially spherical, which means that the plurality of hollow glass microspheres when magnified into a two-dimensional image appear at least substantially circular. A particle will be considered substantially spherical if its outline fits within the intervening space between two, concentric, truly circular outlines differing in diameter from one another by up to about 10% of the diameter of the larger of these outlines.

[0027] The particle size of the hollow glass microspheres can be determined based on techniques known in the art, for example, microscopy, electrical impedance, or light scattering techniques. In the present disclosure, the plurality of hollow glass microspheres has a dso, when measured using a light scattering technique of at least 2, 5, or even 10 micrometers and at most 15, 18, or even 20 micrometers.

[0028] In one embodiment, the plurality of hollow glass microspheres of the present disclosure has a unimodal particle size distribution. In another one embodiment, the plurality of hollow glass microspheres of the present disclosure has a multimodal particle size distribution, for example, bimodal.

[0029] In one embodiment of the present disclosure, the plurality of hollow glass microspheres has a narrow particle size distribution. d o, referred to herein as d o, is the diameter on a particle size distribution curve, where 90 percent by volume of hollow glass microspheres fall below this diameter value. In the present disclosure, the plurality of hollow glass microspheres has a dso to d o ratio greater than 0.4, or even 0.5. The d o measurement can be used to identify the width of the particle size distribution, where a dso to d9o ratio of 1.0 would mean that the d9o value is the same as the dso value.

[0030] Hollow glass microspheres can be made by techniques known in the art. In one embodiment, a milled frit, commonly referred to as "feed", which contains mineral components of glass and a blowing agent (e.g., sulfur or a compound of oxygen and sulfur) is heated at high temperatures. Upon heating, the blowing agent causes expansion of the molten frit to form hollow glass microspheres. In one embodiment, the frit is sorted by size prior to making the hollow glass microspheres, which can result in a plurality of hollow glass microspheres having a controlled particle size distribution, which is known in the art.

[0031] When making hollow glass microspheres, the batch may have any composition that is capable of forming a glass, typically, on a total weight basis, the batch comprises from 50 to 90 percent of S1O2, from 2 to 20 percent of alkali metal oxide, from 1 to 30 percent of B2O3, from

0.005-0.5 percent of sulfur (for example, as elemental sulfur, sulfate or sulfite), from 0 to 25 percent divalent metal oxides (for example, CaO, MgO, BaO, SrO, ZnO, or PbO), from 0 to 10 percent of tetravalent metal oxides other than S1O2 (for example, T1O2, MnC>2, or ZrO_j), from 0.5 to 10 percent of trivalent metal oxides (for example, AI2O3, Fe2C>3, or Sb2C>3), from 0 to 15 percent of oxides of pentavalent atoms (for example, P2O5 or V2O5). Additional ingredients are may be included to provide particular properties or characteristics (for example, hardness or color) to the resultant hollow glass microspheres

[0032] In some embodiments, hollow glass microspheres useful for practicing the present disclosure are surface treated. In some embodiments, the hollow glass microspheres are surface treated with a coupling agent such as a zirconate, silane, or titanate. Typical titanate and zirconate coupling agents are known to those skilled in the art and a detailed overview of the uses and selection criteria for these materials can be found in Monte, S.J., Kenrich Petrochemicals, Inc., "Ken-React® Reference Manual - Titanate, Zirconate and Aluminate Coupling Agents", Third Revised Edition, March, 1995. Suitable silanes are coupled to glass surfaces through condensation reactions to form siloxane linkages with the siliceous surfaces. The treatment renders the microspheres more wet-able or promotes the adhesion of materials to the microsphere surface. This provides a mechanism to bring about covalent, ionic or dipole bonding between hollow glass microspheres and organic matrices. Silane coupling agents may be chosen based on the particular functionality desired. Suitable silane coupling strategies are outlined in Silane Coupling Agents: Connecting Across Boundaries, by Barry Arkles, pg 165 - 189, Gelest Catalog 3000-A Silanes and Silicones: Gelest Inc. Morrisville, PA. In some embodiments, useful silane coupling agents have amino functional groups (e.g., N-2-(aminoethyl)-3-aminopropyltrimethoxysilane and (3- aminopropyl)trimethoxy silane). In compositions of the present disclosure, it may be useful to employ a combination of amino-functional silane and a maleic anhydride modified polyolefin (e.g., polyethylene or polypropylene) in a polyolefin based composition to enhance the coupling between the hollow glass microspheres and the polyolefin base resin. In some embodiments, it may be useful to use a coupling agent that contains a polymerizable moiety, thus incorporating the material directly into the polymer backbone. Examples of polymerizable moieties are materials that contain olefinic functionality such as styrenic, vinyl (e.g., vinyltriethoxy silane, vinyltri(2- methoxyethoxy) silane), acrylic and methacrylic moieties (e.g., 3- metacrylroxypropyltrimethoxysilane). Other examples of useful silanes that may participate in crosslinking include 3-mercaptopropyltrimethoxysilane, bis(triethoxysilipropyl)tetrasulfane (e.g., available under the trade designation "SI-69" from Evonik Industries, Wesseling, Germany), and thiocyanatopropyltriethoxysilane. If used, coupling agents are commonly included in an amount of about 1 to 3% by weight, based on the total weight of the hollow glass microspheres.

[0033] In some embodiments, the hollow glass microspheres useful for practicing the present disclosure are provided with an organic acid or mineral acid coating as described in U.S. Pat. No. 3,061,495 (Alford). In some embodiments, the hollow glass microspheres are treated with an aqueous solution of sulfuric acid, hydrochloric acid, or nitric acid at a concentration and for a time sufficient to reduce the alkali metal concentration of hollow glass microspheres.

[0034] The coating composition of the present disclosure includes the plurality of hollow glass microspheres and a film-forming polymer.

[0035] Film-forming polymers include those known in the art, including both synthetic and natural resins. Exemplary film-forming polymers include: acrylic (which includes both acrylic and methacrylic such as poly(methyl methacrylate-co-ethyl acrylate) or poly(methyl acrylate-co- acrylic acid), acrylic copolymers (such as acrylic-styrene copolymers (e.g., poly(styrene-co-butyl acrylate) and n-butyl acrylate-acrylonitrile-styrene copolymers) or vinyl-acrylic copolymers (e.g., poly(vinyl acetate/methyl acrylate)), vinyl acetate (e.g., poly(vinylidene chloride/vinyl acetate), vinyl acetate/ethylene (VAE), modified VAE, styrene -butadiene copolymer, polyesters (e.g, polyethylene terephthalate, polyethylene terephthalate isophthalate, or polycaprolactone), polyurethanes (e.g., reaction products of aliphatic, cycloaliphatic or aromatic diisocyanates with polyester glycols or polyether glycols), melamine resins, epoxy, alkyds (commonly known but defined as oil modified polyesters), polyamides, (e.g., polyhexamethylene adipamide), polydienes, (e.g., poly(butadiene/styrene)), poly(vinylidene fluoride), urea resins, silicone, and mixtures thereof. Such film-forming polymers may be commercially available under the trade designations "EVOCAR" from Dow Chemical Co., Midland, MI and "ROVACE" from Rohm and Haas Co., a wholly owned subsidiary of Dow Chemical Co. and "ACRONAL PLUS 4130" available from BASF Corp., Florian Park, NJ.

[0036] In one embodiment, the glass transition temperature (Tg) of the film -forming polymer may be at most 20, 15, 10, 5, or ever 0°C. At ambient conditions, coating comprising film-forming polymers with a Tg such as those just described will have a viscosity that allows the polymer droplets in the latex to coalesce. In one embodiment, it is believed the addition of hollow glass microspheres can improve the mechanical properties of these film-forming polymers in the dry state. [0037] In one embodiment, the coating composition comprises the hollow glass microspheres of the present disclosure in an amount of 1, 2, 3, 4, or even 5 % by volume and at most 8, 10, or even 15% by volume.

[0038] Depending on the coating composition, a liquid carrier may be used along with the plurality of hollow glass microspheres and the film-forming polymer. The liquid carrier may be aqueous, organic, or a combination thereof.

[0039] In coating compositions not comprising a liquid carrier, the amount of film-forming polymer present may be at least 10, 20 or 30 or even 40 % by volume and at most 60, 70, 80, or even 95 vol% relative to the coating composition.

[0040] In coating compositions comprising a liquid carrier, such as in paints, the amount of film- forming polymer present may be at least 10, 15, 20, or even 30 vol. %; at most 40, 50, or even 60 vol.% relative to the coating composition.

[0041] In one embodiment, the coating composition comprises at least 30, 40, or even 45% by volume and at most 70, 65, or even 60% by volume of water based on the total weight of the coating composition.

[0042] In one embodiment, the coating composition may comprise an additive to improve the performance or impart various properties to the coating composition, as are known in the art. Additives may be added to modify the color, surface tension, improve flow properties, improve the finished appearance, improve the stability, impart antifreeze properties, control foaming, control skinning, etc. of the coating composition.

[0043] Examples of types of additives that may be added to the coating composition of the present disclosure, include: a pigment, a coalescent, a dye, a dispersing agent, a surfactant, a filler, preservatives (such as biocides), a defoamer, a thickner, a humectant, and combinations thereof. Additional additives include, for example, anti-corrosive pigment enhancers, curing agents, wetting agents, thickeners, rheology modifiers, plasticizers, waxes, anti-oxidants, antifoaming agents, antisettling agents, antiskinning agents, corrosion inhibitors, de hydrators, antigassing agents, driers, antistatic additives, flash corrosion inhibitors, floating and flooding additives, in- can and in-film preservatives, insecticidal additives, optical whiteners, reodorants, flatteners, de- glossing agents, ultraviolet absorbers, and the like and combinations thereof.

[0044] A pigment is a particulate incorporated into the coating composition to provide opacity, color, and other optical or visual effects. Pigments are those which are known in the art. White pigments include: titanium dioxide, zinc oxide, lithopone, antimony oxide, and zinc sulfide. Non- white pigments include cadmium yellow, yellow oxides, pyrazolone orange, perinone orange, cadmium red, red iron oxide, prussian blue, ultramarine, cobalt blue, chrome green, and chromium oxide. [0045] The amount of pigment used in the coating composition of the present disclosure is determined by the pigment's intensity and tinctorial strength, the required opacity, the required gloss, and/or the resistance and durability desired. In one embodiment, the coating composition comprises at least 1, 2, 3, 4 or even 5 % by volume of titanium dioxide particles; and at most 7, 8, 9, 10, 12, or even 15 % by volume of titanium dioxide particles.

[0046] A coalescing agent is a solvent that is used to aid in the coalescence of the film-forming polymers and will evaporate upon drying of the coating composition. Coalescing agents function to externally and temporarily plasticize the film-forming polymer for a time sufficient to develop film formation, but then diffuse out of the coalesced film after film formation, which permits film formation and subsequent development of the desired film hardness by the volatilization of the coalescent. Internal plasticization is based on coreaction of soft monomers with hard monomers to form a polymeric copolymer binder, such as 80/20 vinyl acetate/butyl acrylate, to obtain the desired film-forming characteristics. Exemplary coalescing solvents include: aliphatics, aromatics, alcohols (such as isopropanol, propylene glycol, ethylene glycol, and methanol), ketones (such as trichlorethyleneacetone, methyl ethyl ketone, and methyl isobutyl ketone), white spirit, petroleum distillate, esters (such as ethyl acetate and n-isobutyl acetates), glycol ethers, perchlorethylene, volatile low-molecular weight synthetic resins, and combinations thereof, for example, ester alcohols such as 2,2,4-trimethyl-l,3-pentanediol monoisobutyrate (an ester alcohol available from Eastman Chemical Company, Kingsport, TN, under the trade designation "TEXANOL").

Typically, the coalescing agent is present in a low concentration, typically less than 10, 5 or even 1 wt% based on the total coating composition.

[0047] A dispersing agent may be added to the coating composition for wetting and/or stabilization purposes. The dispersing agent can be a non-ionic or an anionic compound, typically a polymer, such polyvinyl pyrrolidone. Such dispersing agents are known in the art.

[0048] A surfactant may be added to the coating composition to reduce the surface tension and/or for stabilization purposes. The surfactant can be non-ionic, cationic, anionic, or a zwitterionic compound. Such surfactants are known in the art and include for example, those sold under the trade designation "TRITON" and "TERGITOL" by Dow Chemical Co., Midland, MI.

[0049] The proportion of dispersing agent and/or surfactant depends upon the dispersant or surfactant or combinations used and the particular coating composition. The amount added can be determined by routine experimentation.

[0050] Fillers are usually made of inexpensive and inert materials and are added to the coating composition for various purposes, such as to thicken the composition, support its structure and simply increase the volume of the composition. For example, in paints, the fillers have little or no effect on hue, although they may reduce the chroma (that is the intensity) of the hue. They may also enhance opacity, control surface sheen, and facilitate the ease of sanding for example.

[0051] Fillers for coating compositions are known in the art. The filler can be classified as either natural or synthetic types. Exemplary fillers include: diatomaceous earth, talc, lime, clay, fine quartz sand, various clays, blanc fix, calcium carbonate, mica, silicas, aluminum silicate, magnesium silicate, barium sulphate, nepheline syenite, and solid ceramic particles (i.e., particles which have a crystalline phase and do not comprise a hollow core. Exemplary synthetics fillers include engineered molecules or polymeric structures such as "ROPAQUE ULTRA" by Dow Chemical, Midland, MI; and the like. In one embodiment, these fillers may be added at least 5, 7, 10, or even 12 volume %; and no more than 18, 20, 22, 25, 27, or even 30 volume % of fillers are used in the total paint composition. The fillers disclosed above do not have the unique property of a high strength to density ratio as seen in the hollow glass microspheres of the present disclosure (for example, a solid microsphere such as ceramic or silica has a high strength, but also high density).

[0052] Other known additives, such as metal flake and/or pearlescent pigments may be added to modify the visual characteristics of the coating composition and the resulting film.

[0053] In one embodiment, the coating composition of the present disclosure further comprises a preservative, a defoamer, a thickener, and/or a humectant. These additives are commercially available. Examples of preservatives include biocides, in particular Bronopol/(CIT/MIT).

Examples of defoamers are polysiloxanes. Examples of humectants include: propylene glycol, ethylene glycol, polyethylene glycol, glycerol, sucrose, and combinations thereof. Examples of thickeners include both polymeric and inorganic and include are those sold under the trade designations "ATTAGEL" by BASF Corp., Florham Park, NJ; "ACRYSOL RM" by Rohm and Haas, a wholly owned subsidiary of Dow Chemical, Midland, MI; "NATROSOL PLUS" by Ashland Inc., Covington, KY.; and "LATTICE" by FMC BioPolymer, Philadelphia, PA.

[0054] In the present disclosure, the plurality of hollow glass microspheres and the film-forming polymer can be combined using techniques known in the art.

[0055] In one embodiment, the coating composition is a paint composition. For example, in one embodiment, the dry ingredients such as pigments and fillers, along with a surfactant and/or dispersing agents, are mixed with a suitable medium (such as a liquid) to form the millbase. This is the grind stage and is characterized by high shear rates. The millbase is then gradually diluted with the balance of the ingredients of the paint formulation (typically the vehicle and the film- forming polymer) and any final additives are then added to form the desired paint composition. This let down phase is characterized by lower shear rates than the grind stage. [0056] The coating compositions of the disclosure are stable. For example, the coating compositions are stable dispersions that remain dispersed over useful time periods without substantial agitation or which are easily redispersed with minimal energy input (e.g., stirring or shaking).

[0057] As used herein, "separate" means that the solid particles in a liquid dispersion gradually settle or cream, forming distinct layers with very different concentrations of the solid particles and continuous liquid phase. For a dispersion with good dispersion stability, the particles remain approximately homogeneously distributed within the continuous phase. For a dispersion with poor dispersion stability, the particles do not remain approximately homogeneously distributed within the continuous phase and may separate. The amount of material that separates, if any, and its properties are indicative of the settling behavior of the dispersion.

[0058] In one embodiment, the coating compositions of the present disclosure have a low to zero volatile organic solvent contents (VOC). Generally speaking, such compositions will have a VOC of less than about 100 grams/liter. The VOC content may be measured, for example, by ASTM D3960-5 (2013) Standard Practice for Determining Volatile Organic Compound (VOC) Content of Paints and Related Coatings. In many locations, VOCs are regulated and the regulations may differ from locale to locale. Therefore, what may be considered a non-VOC in one locale may be a VOC in another. According to 40 CFR (Code of Federal Regulations) §51.100(s): VOC means any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions. 40 CFR §51.100(s) recites a list of organic compounds which are determined to have negligible photochemical reactivity and are thus, not considered VOCs. As of the date of filing, exemplary non-VOC solvents according to 40 CFR §51.100(s) include for example, acetone, and methyl acetate. See 40 CFR §51.100(s) for a complete list of non-VOC solvents.

[0059] In one embodiment, the coating compositions of the present invention have a viscosity allowing for ease of application. In other words, the coating composition is flowable. Depending on the coating composition, the viscosity can be measured using a Brookfield RVT viscometer using a 3, 4, 5, 6 or 7 spindle at greater than 5, 6, 8, or even 10 rpm (revolutions per minute). Preferably, the viscosity is less than about 100,000 centipoise (cP), 10000 cP, 5000 cP, 2500 cP, 2000 cP, 1500 cP, lOOOcP or even 500 cP. In one embodiment, viscosities are measured with a

Brookfield KU-2 Viscometer as described by ASTM method D562-10 (2014) Method B "Standard Test Method for Consistency of Paints Measuring Krebs Unit Viscosity Using a Stormer-Type Viscometer". It has been discovered that when the hollow glass microspheres of the present disclosure are added to coating compositions such as architectural paints, the coating compositions show heat aged viscosity stability. In other words, when the coating compositions are heated at 49°C for 14 days, the change in viscosity between the initial viscosity and the heat aged viscosity is less than 15, 12, 10, or even 8 Krebs units (KU).

[0060] The coating compositions of the present disclosure can be applied to a surface by various means including, but not limited to, brushing, rolling, spraying and the like. Generally, a coating is applied to a surface and forms a wet film. Examples of surfaces to which the coating composition can be applied include: wood, plastic, metal, cement, ceramic, paper, asphalt, plaster, plasterboard, previously primed or coated surfaces, and the like. The coating compositions of the present disclosure are applied such that the resulting film has a cross-sectional thickness of at least 25, 30, 40, or even 50 micrometers; and at most 80, or even 100 micrometers.

[0061] After coating, the film-forming polymer (also known as a binder) anneals (via coalescing, curing, or combinations thereof) to form a film.

[0062] In one embodiment, film formation of the coating composition occurs when the coating composition is applied to a substrate and the carrier liquid evaporates. During this process, the particles of binder (and optional pigment) come closer together. As the last vestiges of liquid evaporate, capillary action draws the binder particles together with great force, causing them to fuse into a continuous film in a process often referred to as coalescence. In coating applications such as paints, the film-forming polymer imparts adhesion, binds the pigments together, and strongly influences such properties as gloss potential, exterior durability, flexibility, and toughness.

[0063] In another embodiment, the coating composition comprises little to no liquid carrier and upon thermal or photo-initiation cures or crosslinks the binder forming a film.

[0064] In the present disclosure, it has been discovered that by using a plurality of hollow glass microspheres in a coating composition with a particular composition disclosed herein, that films can be generated that have improved performance characteristics such as opacity and tint, while offering sufficient scrub resistance.

[0065] PVC (pigment volume concentration) is used to describe the volume ratio of all pigments (including for example primary pigment, secondary pigment, and fillers) in the coating composition to the total non-volatiles present. Typically, a lower PVC value results in better durability and higher gloss of the coating composition (e.g., a paint) and a higher PVC value has a better hiding. For most coating compositions (especially in paint applications) there is a critical PVC value, wherein there is just the right amount of binder present to fill the voids of the pigment particles. Additionally, pigments and binders are expensive components of paint. Thus, it would be desirable to not use as much binder to wet-out the fillers and pigments. In one embodiment, the PVC value of the resulting film is at least 10, 20%, 25%, 30%, 35% or even 40%; and no more than 50%, 55%, 60%, 65%, or even 70%. In another embodiment, the PVC value is at least 8%, 10%, or even 12% and no more than 18%, 20% or even 25%.

[0066] Exemplary coating compositions that may be improved by the hollow glass microspheres disclosed herein are those coating compositions comprising a film-forming polymer such as architectural paint (e.g., for indoor or outdoor applications), floor polishes and finishes, varnishes for a variety of substrates (e.g., wood floors), waterborne gels applied in the manufacture of photographic film, automotive or marine coatings (e.g., primers, base coats, or topcoats), sealers for porous substrates (e.g., wood, concrete, or natural stone), hard coats for plastic lenses, coatings for metallic substrates (e.g., cans, coils, electronic components, or signage), inks (e.g, for pens or gravure, screen, or thermal printing), and coatings used in the manufacture of electronic devices (e.g., photoresist inks).

[0067] Exemplary embodiments of the present disclosure include, but are not limited to the following:

[0068] Embodiment 1. A coating composition comprising: a plurality of hollow glass microspheres wherein the plurality of hollow glass microspheres comprises, on an equivalent weight basis, more than 0.5% of AI2O3; and at least one film-forming polymer.

[0069] Embodiment 2. The coating composition of embodiment 1, wherein the plurality of hollow glass microspheres comprises, on an equivalent weight basis, more than 1.0% of

AI₂O3. Embodiment 3. The coating composition of any one of the previous embodiments, wherein the plurality of hollow glass microspheres has a ratio, on an equivalent weight basis, of AI2O3 to the sum of all other inorganic oxides present except for Si02 is greater than 0.01.

[0070] Embodiment 4. The coating composition of claim 3, wherein the all other inorganic oxides comprise B₂0₃, CaO, Fe₂0₃, K₂0, MgO, Na₂0, P₂0₅, S0₃, Ti0₂, and ZnO.

[0071] Embodiment 5. The coating composition of claim 3, wherein the all other inorganic oxides consists of B₂0₃, CaO, Fe₂0₃, K₂0, MgO, Na₂0, P₂0₅, S0₃, Ti0₂, and ZnO.

[0072] Embodiment 6. The coating composition of any one of the previous embodiments, wherein the plurality of hollow glass microspheres comprises, on an equivalent weight basis, more than 2.0% of A1₂0₃.

[0073] Embodiment 7. The coating composition of any one of the previous embodiments, wherein the plurality of hollow glass microspheres further comprises, on an equivalent weight basis, more than 1% by weight of ZnO.

[0074] Embodiment 8. The coating composition of any one of the previous embodiments, wherein the hollow glass microspheres have an average true density greater than 0.8 g/mL.

[0075] Embodiment 9. The coating composition of any one of the previous embodiments, wherein the hollow glass microspheres have a dso of no more than 20 micrometers. [0076] Embodiment 10. The coating composition of any one of the previous embodiments, wherein the hollow glass microspheres comprise silica and a boron trioxide.

[0077] Embodiment 11. The coating composition of any one of the previous embodiments, wherein the hollow glass microspheres have a survival at 206 MPa of at least 90% per the % Survival Test Method.

[0078] Embodiment 12. The coating composition of any one of the previous embodiments, wherein the coating composition comprises 1 to 15 % by volume of the plurality of hollow glass microspheres.

[0079] Embodiment 13. The coating composition of any one of the previous embodiments, further comprising a liquid carrier.

[0080] Embodiment 14. The coating composition of embodiment 13, wherein the liquid carrier is water.

[0081] Embodiment 15. The coating composition of embodiment 14, wherein the water comprises 30% to 70% volume of the coating composition.

[0082] Embodiment 16. The coating composition of any one of the previous embodiments, wherein the film-forming agent comprises at least one of polyvinyl acetate, acrylic, styrene- butadiene copolymers, and combinations thereof.

[0083] Embodiment 17. The coating composition of any one of the previous embodiments, wherein the at least one film -forming polymer comprises 10 to 40 volume % of the coating composition.

[0084] Embodiment 18. The coating composition of any one of the previous embodiments, wherein the coating composition further comprises a dispersant, a surfactant, or combinations thereof.

[0085] Embodiment 19. The coating composition of any one of the previous embodiments, wherein the coating composition further comprises a pigment, a dye, or combination thereof.

[0086] Embodiment 20. The coating composition of any one of the previous embodiments, wherein the coating composition further comprises a coalescent.

[0087] Embodiment 21. The coating composition according to embodiment 20, wherein the coalescent is selected from the group consisting of: ester alcohols, alcohols, glycol ethers, and combinations thereof.

[0088] Embodiment 22. The coating composition of any one of the previous embodiments, wherein the coating composition further comprises a filler.

[0089] Embodiment 23. The coating composition according to embodiment 22, wherein the filler comprises at least one of diatomaceous earth, talc, lime, clay, fine quartz sand, various clays, blanc fix, calcium carbonate, mica, silicas, aluminum silicate, magnesium silicate, barium sulphate, nepheline syenite, ceramics, and combinations thereof.

[0090] Embodiment 24. The coating composition of any one of the previous embodiments, wherein the coating composition comprises 1 to 10 % by volume of titanium dioxide particles.

[0091] Embodiment 25. The coating composition of any one of the previous embodiments, wherein the inorganic content of the hollow glass microspheres is tested by the Inorganic

Elemental Analysis.

[0092] Embodiment 26. A coating composition, comprising a film forming polymer, and a plurality of hollow glass microspheres, wherein the plurality of hollow glass microspheres comprise, on an equivalent weight basis: from 50-75 % of silica, 8-15 % of calcium oxide; greater than 2 % of boria, 0.5-5 % of phosphorous pentoxide; 0.5-5 % of zinc oxide; greater than 1 % of alumina; and 0-7% of sodium oxide.

[0093] Embodiment 27. A film comprising: a binder, and a plurality of hollow glass microspheres wherein the plurality of hollow glass microspheres comprises, on an equivalent weight basis, more than 0.5% of A1₂0₃.

[0094] Embodiment 28. A film of embodiment 27, wherein the hollow glass microspheres further comprises, on an equivalent weight basis more than 1% of ZnO.

[0095] Embodiment 29. The film of any one of embodiments 27-28, wherein the binder comprises at least one of polyvinyl acetate, acrylic, styrene-butadiene copolymers, and combinations thereof.

[0096] Embodiment 30. The film of any one of embodiments 27-29, further comprising an additive, wherein the additive comprises at least one of a filler, a pigment, a rheology modifier, and a surfactant.

[0097] Embodiment 31. The film of any one of embodiments 27-30, wherein the film has a cross- sectional thickness of 25 micrometers to 100 micrometers.

EXAMPLES

[0098] Advantages and embodiments of this disclosure are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. In these examples, all percentages, proportions and ratios are by weight unless otherwise indicated.

[0099] All materials are commercially available, for example from Sigma-Aldrich Chemical Company; Milwaukee, WI, or known to those skilled in the art unless otherwise stated or apparent. These abbreviations are used in the following examples: g = gram, hr = hour, kg = kilograms, min = minutes, mol = mole; cm= centimeter, KU = Krebs Unit, mm = millimeter, mL = milliliter, L = liter, MPa = megaPascals, rpm = revolutions per minute, ppm = parts per million, psi = pounds per square inch, s = second, slm = standard liter per minute used at ambient conditions (e.g., 25°C and 1 bar pressure), W = Watt, and wt = weight.

Ή-PURE R-706 Rutile titanium dioxide pigment, 2.4 g/cc true density with 1-24

micron size range, commercially available from DuPont, Wilmington, DE available under the trade designation "TI-PURE R-06"

MINEX 4 A micronized functional filler and/or extender produced from

nepheline syenite; a naturally occurring, silica deficient, sodium- potassium alumina silicate, obtained from Unimin Corporation, New Canaan, CT under trade designation "MINEX 4"

DURAMITE A coarse, unique, medium particle size calcium carbonate, obtained from Imerys Carbonates, Roswell, GA under trade designation "DURAMITE"

Additive A An engineered solid ceramic microsphere of alkali alumina silicate obtained from 3M, St. Paul MN under the trade designation "W-410 Ceramic Microsphere"

Additive B A hollow glass bubble of high strength and a density of 0.6 g/cc

obtained from 3M, St. Paul MN under the trade designation "iM30K"

ACRONAL 4130 All acrylic latex for less than 50 g/L VOC semi -gloss paints with

outstanding block resistance and enhanced titanium dioxide efficiency, obtained from BASF Corporation, Florham Park, NJ under trade designation "ACRONAL 4130"

LOXANOL CA 5120 Non-ionic surfactant used as a high performance, zero, VOC,

coalescing agent for waterborne coatings, obtained from BASF Corporation, Florham Park, NJ under the trade designation

"LOXANOL CA 5120

ACRYSOL TT-935 A hydrophobically modified anionic thickener commercially available from Dow Chemical, Midland, MI, available under the trade designation "ACRYLSOL TT-935"

RHEOVIS PE 1331 A polyether solution in water used as a solvent-free, VOC-free, low odor associative thickener obtained from BASF Corporation, Florham Park, NJ under the trade designation "RHEOVIS PE 1331"

POLYPHASE 678 A zero VOC, full-spectrum dry-film preservative consisting of active substances methylbenzimidazole -2-yl Carbamate (15%) and 3-Ido-2- propynyl butyl Carbamate (5%) obtained from Troy Corporation, Florham Park, NJ under the trade designation "POLYPHASE 678" RHEOVIS PU1191 An associative polyurethane thickener obtained from BASF, Florham Park, NJ under the trade designation "RHEOVIS PU 1191"

[00100] Additive C- Preparation of the hollow glass microsphere starting from the glass melting. The raw materials for all ingredients are weighed separately. They are silica 667.96 g, lime 255.22 g, borax 95.38 g, tetra sodium pyrophosphate 41.21 g, sodium sulfate 8.78 g, sodium ash 2.15 g, zinc oxide 55 g, and aluminum silicate 87.41 g. They then are mixed in a mixer at 7200 rpm for 80 second. The mixed powder is transferred into a fused silica crucible and then is placed into a box furnace set to 2450°F (1,343 °C). The total melting time is 4 hours. At the end of melting, the glass is poured into a water filled metal bucket. The glass frit is milled down first by a disk milling and then by an air jet milling. The particle size is about 9 micrometers in dso- In the forming step, the flame conditions are: 30 slm for natural gas, 240 slm for the air, 5 slm for oxygen. The glass feeding rate is set to 15 g/min.

[00101] Additive D- Preparation of the hollow glass microsphere starting from the glass melting. The raw materials for all ingredients are weighed separately. The raw materials are silica 667.96 g, lime 255.22 g, borax 95.38 g, tetra sodium pyrophosphate 41.21 g, sodium sulfate 8.78 g, sodium ash 20.96 g, zinc oxide 55 g, and aluminum silicate 87.41 g. The raw materials then are mixed in a mixer at 7200 rpm for 80 second. The mixed powder is transferred into a fused silica crucible and then is placed into a box furnace set to 2450°F (1,343 °C). The total melting time is 4 hours. At the end of melting, the glass is poured into a water filled metal bucket. The glass frit is milled down first by a disk milling and then by an air jet milling. The particle size is about 9 micrometers in dso. In the forming step, the flame conditions are: 30 slm for natural gas, 240 slm for the air, 5 slm for oxygen. The glass feeding rate is set to 15 g/min.

[00102] Additive E- Preparation of the hollow glass microsphere starting from the glass melting. The raw materials for all ingredients are weighed separately. The raw materials are silica 667.96 g, lime 255.22 g, borax 96.38 g, tetra sodium pyrophosphate 42.21 g, sodium sulfate 8.78 g, sodium ash 21.96 g, zinc oxide 45 g, and aluminum silicate 71.89 g. The raw materials then are mixed in a mixer at 7200 rpm for 80 second. The mixed powder is transferred into a fused silica crucible and then is placed into a box furnace set to 2450°F (1,343 °C). The total melting time is 4 hours. At the end of melting, the glass is poured into a water filled metal bucket. The glass frit is milled down first by a disk milling and then by an air jet milling. The particle size is about 10 micrometers in dso- In the forming step, the flame conditions are: 30 slm for natural gas, 190 slm for the air, 8 slm for oxygen. The glass feeding rate is set to 80 g/min.

[00103] Additive F- Preparation of the hollow glass microsphere starting from the glass melting. The raw materials for all ingredients are weighed separately. The raw materials are silica 645.78 g, lime 255.22 g, borax 95.38 g, tetra sodium pyrophosphate 41.21 g, sodium sulfate 8.78 g, sodium ash lOg, zinc oxide 45 g, and aluminum silicate 70.85 g. The raw materials then are mixed in a mixer at 7200 rpm for 80 second. The mixed powder is transferred into a fused silica crucible and then is placed into a box furnace set to 2450°F (1,343 °C). The total melting time is 4 hours. At the end of melting, the glass is poured into a water filled metal bucket. The glass frit is milled down first by a disk milling and then by an air jet milling. The particle size is about 10 micrometers in dso. In the forming step, the flame conditions are: 30 slm for natural gas, 170 slm for the air, 15 slm for oxygen. The glass feeding rate is set to 140 g/min.

[00104] Additive G- Preparation of the hollow glass microsphere starting from the glass melting. The raw materials for all ingredients are weighed separately. The raw materials are silica 687.96 g, lime 255.22 g, borax 95.38 g, tetra sodium pyrophosphate 44.21 g, sodium sulfate 8.78 g, sodium ash 23.96 g, zinc oxide 47 g, and aluminum silicate 35.94 g. The raw materials then are mixed in a mixer at 7200 rpm for 80 second. The mixed powder is transferred into a fused silica crucible and then is placed into a box furnace set to 2450°F (1,343 °C). The total melting time is 4 hours. At the end of melting, the glass is poured into a water filled metal bucket. The glass frit is milled down first by a disk milling and then by an air jet milling. The particle size is about 10 micrometers in dso. In the forming step, the flame conditions are: 30 slm for natural gas, 180 slm for the air, 5 slm for oxygen. The glass feeding rate is set to 80 g/min. [00105] Particle Size

[00106] The particle sizes of the Additives were determined by laser diffraction (using a

Model S3500 Particle Size Analyzer obtained from Microtrac, Montgomeryville, PA) operating in the wet mode with water as a medium. The procedural parameters for each additive are shown in Table 1. The procedure was optimized separately for each Additive. The dso and dc>o particle size results are shown in Table 2 below.

Table 1 : Light scattering parameters

[00107] Density

[00108] The densities of the Additives were determined using a gas pycnometer (from Micromeritics, Norcross, Georgia under trade designation "ACCUPYC 1330 PYCNOMETER") according to ASTM D2840- 69, "Average True Particle Density of Hollow Microspheres". The density results are shown in Table 2, below.

[00109] Strength Test Method

[00110] The strength of the hollow glass microspheres can be measured using ASTM

D3102 -78 "Hydrostatic Collapse Strength of Hollow Glass Microspheres"; with the following modifications. The sample size (in grams) was equal to 10 times the density of the glass bubbles. The microspheres were dispersed in glycerol (20.6 g), and data reduction was automated using computer software. Collapse strength can typically be measured with an accuracy of ± about five percent. Accordingly, each of the collapse strength values provided below can be ± five percent.

The results are reported as the hydrostatic pressure at which 10 percent or 5 prevent by volume of the hollow glass microspheres collapse, also referred to as strength at 90% survival and 95 % survival, respectively. The strength results are reported in Table 2, below.

Table 2

NR = not reported

[00111] Inorganic Elemental Analysis

[00112] The composition of the Additives was determined using inductively coupled plasma atomic emission spectroscopy (ICP-AES). The samples were prepared in duplicate. 50 mg of sample was weighed to the nearest 0.1 mg into 50-mL polypropylene centrifuge tubes. 4.5 mL of 2.5% aqueous mannitol, 3 mL of concentrated hydrochloric acid, 1.5 mL of concentrated nitric acid, and 2 mL of concentrated hydrofluoric acid were then added to the sample tubes and to another two empty tubes for use as controls. The solutions were allowed to stand overnight. Once the samples had fully dissolved, the solutions were diluted to 50 mL with 18.2-MegaOhm deionized water. Prior to analysis, the solutions were diluted an additional 10-fold or 100-fold by volume with 2% nitric acid as needed to bring the analyte concentrations within linear calibration range.

[00113] The instrument used for elemental analysis was an Optima 8300 ICP optical emission spectrophotometer (available from PerkinElmer. Inc., Waltham, MA). The samples were analyzed against external calibration curves generated using acid-matched solution standards containing 0, 0.2, 0.5, and 1 ppm of each analyte. A 0.5-ppm quality control standard was used to monitor the accuracy of the calibration curves during the analysis. A 0.5 ppm scandium solution was run in-line with the samples and standards to serve as an internal standard. The elements screened during this analysis were Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Sb, Si, Sn, Sr, Ti, V, Zn, and Zr. The compositions of the additives are given in Table 3.

These compositions were determined by converting the weight fraction of the element determined by ICP-AES to the oxide form. The weight fraction of the element in the additive is divided by the weight fraction of the element in the oxide The weight fraction of the element in the oxide used in this conversion from the ICP data is shown in the second row of Table 3. For clarity, only elements with an oxide weight fraction of greater than or at least 0.01 % for at least one of the additives are shown in Table 3.

Table 3 : Oxide e uivalent com ositions of additives

† metal oxide was present at a weight fraction less than 0.01%

†† sulfur level not determined

[00114] Preparation of Paint

[00115] Formulation A:

[00116] The paint was prepared in two stages.

[00117] The grind was prepared by mixing in an 800 mL beaker equipped with a 1.5 inch

(38.1 mm) Cowles blade, predetermined amounts of water, KTPP and VANTEX-T at 600 rpm for 4 minutes. Then, a predetermined amount of NATROSOL PLUS 330 was added and allowed to dissolve until it was clear of seeds (which took about 20 minutes). Afterwards, predetermined amounts of FOAMSTAR ST-2438, TAMOL 1 124 and TRITON CF-10 were added to the mixture which was further mixed for 5 minutes at 600 rpm. The predetermined amount of TI -PURE R-706 was added to the liquid mixture over the course of 3 minutes. The mixture was then mixed with the Cowels blade at 2500 rpm for 5 minutes. Separately, predetermined amounts of the dry components MINEX 4, DURAMITE and Additive were blended together using a wooden spatula and the blended dry components were added to above solution over a period of 6 minutes while mixing at 3500 rpm. The mixing was continued another 20 minutes.

[00118] The let-down was prepared by mixing predetermined amounts of water and

ACRONAL 4130 in an 800 mL vessel equipped with a propeller blade at low speed with a vortex pulling about 1 inch (25.4 mm) into the liquid.

[00119] The grind from above was then added to the let-down and the resulting mixture was mixed for 10 minutes. Finally, ACRYSOL TT-935 thickener was added to bring the Krebs unit viscosity of the mixture to approximately 95 KU (+ 2 KU) to complete preparation of the paint. Kreb unit viscosity was measured using a Brookfield KU-2 Viscometer (commercially available form Brookfield AMETEK, Middleborough, MA) as described by ASTM method D562- 10 (2014) Method B "Standard Test Method for Consistency of Paints Measuring Krebs Unit (KU) Viscosity Using a Stormer-Type Viscometer".

[00120] Table 4, below, summarizes the amounts of the various components in preparing the paint mixtures used in the Example and Comparative Examples described below.

Table 4: Paint Formulation A

[00121] Example 1 and Comparative Examples A and B

[00122] Example 1 and Comparative Examples A and B paint mixtures were prepared according to the method for preparation of paint described above.

[00123] For Example 1, the Additive was 33.35 g of Additive C prepared as described above.

[00124] For Comparative Example A, the Additive was 69.40g of Additive A.

[00125] For Comparative Example B, the Additive was 17.35g of Additive B.

[00126] Formulation B.

[00127] Formulation B was prepared in 2 stages. [00128] The grind was prepared by mixing in an 800 mL beaker equipped with a 1.5 inch

(38.1 mm) Cowles blade, predetermined amounts of water, ammonium hydroxide, DISPEX CX 4240, FOAMSTAR ST2420, PROXEL BD-20, and NATROSOL PLUS 330 were added and allowed to dissolve until the solution was clear of seeds (which took about 20 minutes). The predetermined amount of TI -PURE R-706 was added to the liquid mixture over the course of 3 minutes. The mixture was then mixed with the Cowels blade at 1500 rpm for 10 minutes.

Separately, predetermined amounts of the dry components MINEX 4, DURAMITE and Additive were blended together using a wooden spatula and the blended dry components were added to above solution over a period of 6 minutes while mixing at 3500 rpm. The mixing was continued another 20 minutes .

[00129] The let-down was prepared by mixing predetermined amounts of water,

FOAMSTAR ST2420, LOXANOL CA5120, RHEOVIS PE 1331, POLYPHASE 678, and ACRONAL 4130 in an 800 mL vessel equipped with a propeller blade at low speed with a vortex pulling about 1 inch (25.4 mm) into the liquid.

[00130] The grind from above was then added to the let-down and the resulting mixture was mixed for 20 minutes. Finally, RHEOVIS PU 1 191 thickener was added to bring the Krebs unit viscosity of the mixture to approximately 95 KU (+ 2 KU) to complete preparation of the paint. Kreb unit viscosity was measured using a Brookfield KU-2 Viscometer (commercially available form Brookfield AMETEK, Middleborough, MA) as described by ASTM method D562- 10 (2014) Method B "Standard Test Method for Consistency of Paints Measuring Krebs Unit (KU) Viscosity Using a Stormer-Type Viscometer".

[00131] Table 5, below, summarizes the amounts of the various components in preparing the paint mixtures used in the Example and Comparative Examples described below.

Table 5 : Formulation B

[00132] Examples 2, 3, 4, and 5 and Comparative Examples C and D paint mixtures were prepared according to the method for preparation of Formulation B described above.

[00133] For Example 2, the Additive was 27.68 g of Additive D prepared as described above.

[00134] For Example 3, the Additive was 22.18 g of Additive E prepared as described above.

[00135] For Example 4, the Additive was 32.08 g of Additive F prepared as described above.

[00136] For Example 5, the Additive was 22.07 g of Additive G prepared as described above.

[00137] For Comparative Example C, the Additive was 72 g of Additive A.

[00138] For Comparative Example D, the Additive was 18.03 of Additive B.

[00139] Examples 1-5 and Comparative Examples A, B, C, and D were coated on sealed

Leneta 3B opacity charts with a 3 mil (75 micrometers) bird bar and Leneta scrub panels with a 7 mil (178 micrometers) draw down bar (available from Leneta Company, Mahwah, NJ). The paints were allowed to dry under ambient conditions for 7 days. The resulting Examples 1,2,3,4, and 5 and Comparative Examples A, B, C, and D paint samples were tested according to the test methods described below. The test results are summarized in Tables 6 and 7, below.

[00140] Opacity test

[00141] Opacity of the samples was measured using a Colorite colorimeter (available under the trade designation "COLORFELX EZ" from Hunter Lab, Reston, VA ) to measure the Y tristimulus value over white and black regions of the sealed 3B charts. Contrast ratio is the ratio of

Yblack / Ywliite-

[00142] Scrub test

[00143] The scrub test is a measure of the number of passes with abrasive media over a thin shim that a paint can withstand before breaking. The scrub test was performed similarly to the method described in ASTM 2486-06 (2017) Method A. An Elcometer 1720 Abrasion tester (available from Elcometer Inc. Rochester Hills, MI.) was used for the scrub testing. The breaking point was determined by observation across the width of the shim. Two tests were run on at least three paths. The values were averaged to obtain the reported values.

[00144] Burnish test

[00145] The burnish test was performed similarly to the method described in ASTM

D6736-08 (2013) "Standard Test Method for Burnish Resistance of Latex Paints" using a 600 load and measuring the gloss after 20 passes. The reported value is the % change in 85 ⁰ gloss given by

(85° gloss _final - 85°gloss_initial)

% change in gloss =

85° gloss_initial

The 85 ⁰ gloss final is an average of 12 measurements, three measurements taken on four tracks. The 85 ⁰ gloss initai is an average of 12 measurements, three measurements taken on four tracks. An Elcometer 1720 Abrasion tester (available from Elcometer Inc. Rochester Hills, MI.) was used for the burnish testing .

[00146] Washability test

[00147] The wash test was based on ASTM D3450-00 (2010) and used ASTM ST-1 soil as the soilant. The soilant was applied for 16 hours, blotted using a paper towel and a two pound roller, then washed with 5 mL of a 10% detergent solution (dish washing liquid available under the trade designation "DAWN" from Procter & Gamble, Cincinnati, OH) and 2.5 g of water for 25 passes with a sponge. An Elcometer 1720 Abrasion tester (available from Elcometer Inc.

Rochester Hills, MI.) was used for the washability testing. The initial reflectance of the panels was measured at three points in each of two paths before the soiling and washing and the final reflectance was measured at three points in each of two paths after the washing. The ratio of the averages of these six numbers was taken to be the reflectance recovery as given in the following equation. A higher number is better and indicates more of the dark soiling was removed by washing.

Reflectance _final

Reflectance recovery =

Reflectance_initial [00148] Tint test

[00149] Tint strength is a measure of the effectiveness of a pigment to change the color of a coating. For this study, 1 g of BASF PureOptions B Lamp black pigment (obtained from BASF Corporation, Florham Park, NJ under trade designation "PUREOPTIONS B LAMP BLACK") was mixed into 50 g of each of the three paints described above using a Flacktek speed mixer (obtained from FlackTek, Inc, Landrum SC under trade designation "FLACKTEK SPEED MIXER") operating at 1500 rpm for 30 s. The now grey paints were drawn down on sealed 3B Leneta opacity charts and allowed to dry for 1 week. The Y tristimulus reflectance value was measured using a Colorite colorimeter. Tint strength was calculated according to the following equation: TS =(T) [(1-Y )2/2Y]s/[(l-Y)2/2Y]u(T)

where:

TS = tinting strength of test pigment,

Y^' = measured reflectance factor as Y tristimulus as a decimal,

T = assigned tinting strength of standard, usually 100 %,

and subscripts "u" and "s" refer to the pigment of interest and the standard pigment. For this study the standard pigment was Additive A.

[00150] Heat aged viscosity stability

[00151] The stability of architectural paints was measured as the change in Krebs unit viscosity with exposure to heat. For Example 1 and Comparative Examples A and B, 450 g of paint were placed in 500 mL plastic jars. The initial Krebs unit viscosity was measured with a KU-2 Viscometer available from Brookfield, Middleboro, MA. The jars were then sealed with screw-top lids and briefly inverted to coat the jar and lid with paint. For Example 1 and

Comparative examples A and B, these jars were placed in a batch oven at 49 °C for 14 days. The jars were removed and allow to cool for 4 hours to an ambient temperature of 25 °C. The jars were removed and allow to cool for 4 hours to an ambient temperature of 25 °C. The heat aged viscosity of each paint was measured. The delta KU viscosity is recorded as the difference between the heat aged viscosity and the initial viscosity. The initial and final viscosities were measured with ASTM D562-10 (2014) Method B.

[00152] For Examples 2, 3, 4, and 5 and comparative examples C and D, 450 g of paint were placed in 500 mL plastic jars and allowed to equilibrate for 24 hours. The initial Krebs unit viscosity was measured with a KU-2 Viscometer available from Brookfield, Middleboro, MA. these jars were placed in a batch oven at 49°C for 7 days. The jars were removed and allow to cool for 4 hours to an ambient temperature of 25 °C. The heat aged viscosity of each paint after 7 days was measured. The delta KU viscosity is recorded as the difference between the heat aged viscosity(7 days) and the initial (equilibrated) viscosity. The jars were then re-sealed and briefly inverted to coat the jar and lid with paint. These jars were placed in a batch oven at 49°C for and additional 7 days. The delta KU viscosity is recorded as the difference between the heat aged viscosity (e.g., 7 days and/or 14 days) and the initial (equilibrated) viscosity. The initial and final viscosities were measured with ASTM D562-10 (2014) Method B. Table 6: Formulation A Results

[00153] The results for opacity, scrub, washability, burnish, time and heat aged viscosity stability for Example 2, 3, 4 and 5 and Comparative Examples B and C are shown in Table 7 below.

Table 7: Formulation B Results

[00154] The ratio of AI₂O3 versus the sum of the other inorganic oxide minus S1O₂ (in other words, B2O3, CaO, Fe2C>3, K2O, MgO, Na20, P2O5, SO3, T1O2, and ZnO) was calculated and the ratio is shown in Table 8 below along with the Viscosity Stability change in KU over 14 days for the various samples.

Table 8

[00155] Foreseeable modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention. This invention should not be restricted to the embodiments that are set forth in this application for illustrative purposes.

Claims

What is claimed is:

A coating composition comprising

(a) a plurality of hollow glass microspheres wherein the plurality of hollow glass

microspheres comprises, on an equivalent weight basis, more than 0.5% of AI2O3;

(b) at least one film-forming polymer.

The coating composition of claim 1, wherein the plurality of hollow glass microspheres has a ratio, on an equivalent weight basis, of AhCb to the sum of all other inorganic oxides present except for Si02 is greater than 0.01.

The coating composition of claim 2, wherein the all other inorganic oxides comprise B2O3, CaO, Fe₂0₃, K₂0, MgO, Na₂0, P2O5, S0₃, T1O2, and ZnO.

The coating composition of any one of the previous claims, wherein the hollow glass microspheres have an average true density greater than 0.8 g/mL.

The coating composition of any one of the previous claims, wherein the hollow glass microspheres have a dso of no more than 20 micrometers.

The coating composition of any one of the previous claims, wherein the hollow glass microspheres have a survival at 206 MPa of at least 90% per the % Survival Test Method.

The coating composition of any one of the previous claims, further comprising a liquid carrier.

The coating composition of claim 7, wherein the liquid carrier is water and the water comprises 30% to 70% volume of the coating composition.

The coating composition of any one of the previous claims, wherein the coating composition further comprises a dispersant, a surfactant, or combinations thereof.

10. The coating composition of any one of the previous claims, wherein the coating

composition further comprises a coalescent and wherein the coalescent is selected from the group consisting of: ester alcohols, alcohols, glycol ethers, and combinations thereof.

1 1. The coating composition of any one of the previous claims, wherein the coating composition further comprises a filler and wherein the filler comprises at least one of: diatomaceous earth, talc, lime, clay, fine quartz sand, various clays, blanc fix, calcium carbonate, mica, silicas, aluminum silicate, magnesium silicate, barium sulphate, nepheline syenite, ceramics, and combinations thereof.

12. The coating composition of any one of the previous claims, wherein the inorganic content of the hollow glass microspheres is tested by the Inorganic Elemental Analysis test.

13. A coating composition, comprising a film forming polymer, and a plurality of hollow glass microspheres, wherein the plurality of hollow glass microspheres comprise, on an equivalent weight basis: from 50-75 % of silica, 8-15 % of calcium oxide; greater than 2 % of boria, 0.5-5 % of phosphorous pentoxide; 0.5-5 % of zinc oxide; greater than 0.5% of alumina; and 0-7% of sodium oxide.

14. A film comprising

a. a binder

b. a plurality of hollow glass microspheres wherein the plurality of hollow glass

microspheres comprises, on an equivalent weight basis, more than 0.5% of AI₂O3.

A film of claim 14, wherein the plurality of hollow glass microspheres has a ratio, on an equivalent weight basis, of AI₂O3 to the sum of all other inorganic oxides present except for S1O2, is greater than 0.01.