AGGLOMERATED MINERAL COMPOSITES

Abstract

An agglomerated mineral composite coating composition may include a coating vehicle, an agglomerated mineral composite including a first inorganic particulate mineral, a second inorganic particulate mineral, and a binder. The binder may facilitate agglomeration of the first inorganic particulate mineral and the second inorganic particulate mineral. A method of making a coating composition including agglomerated mineral composites may include adding a first inorganic particulate material to a second inorganic particulate material to form a mixture, adding a binder to the mixture to form agglomerated mineral composites, and adding the agglomerated mineral composites to a coating vehicle. The first and second inorganic particulate materials may include diatomaceous earth, mica, perlite, aluminosilicate, talc, and an alkali earth metal carbonate. The aluminosilicate may include kaolin. The alkali earth metal carbonate may include calcium carbonate. The binder may include sodium silicate. The coating composition may include not more than 10% by weight titanium dioxide.

Claims

1. An agglomerated mineral composite coating composition comprising: a coating vehicle; an agglomerated mineral composite including a first inorganic particulate mineral, a second inorganic particulate mineral, and a binder, wherein the binder facilitates agglomeration of the first inorganic particulate mineral and the second inorganic particulate mineral.

2. The agglomerated mineral composite coating composition of claim 1, further comprising not more than 10% by weight titanium dioxide relative to the coating composition.

3. The agglomerated mineral composite coating composition of claim 1, wherein the first inorganic particulate material comprises a material chosen from the group consisting of diatomaceous earth, mica, and perlite.

4. The agglomerated mineral composite coating composition of claim 3, wherein the second inorganic particulate material comprises a material chosen from the group consisting of an aluminosilicate, talc, and an alkali earth metal carbonate.

5. The agglomerated mineral composite coating composition of claim 4, wherein the aluminosilicate comprises kaolin.

6. The agglomerated mineral composite coating composition of claim 1, wherein the first inorganic particulate material comprises diatomaceous earth, and the second inorganic particulate material comprises kaolin.

7. The agglomerated mineral composite coating composition of claim 1, wherein the first inorganic particulate material comprises perlite, and the second inorganic particulate material comprises kaolin.

8. The agglomerated mineral composite coating composition of claim 1, wherein the binder comprises an inorganic binder.

9. The agglomerated mineral composite coating composition of claim 8, wherein the inorganic binder comprises an alkali metal silicate.

10. The agglomerated mineral composite coating composition of claim 8, wherein the inorganic binder comprises a cement.

11. The agglomerated mineral composite coating composition of claim 8, wherein the inorganic binder comprises a magnesium aluminum silicate clay.

12. The agglomerated mineral composite coating composition of claim 1, wherein the binder comprises an organic-to-inorganic binder.

13. The agglomerated mineral composite coating composition of claim 12, wherein the organic-to-inorganic binder comprises at least one of silicone or ethyl silicate.

14. The agglomerated mineral composite coating composition of claim 1, wherein the binder comprises an organic binder.

15. The agglomerated mineral composite coating composition of claim 1, wherein the agglomerated mineral composites have a median particle size (d.sub.50) substantially similar to the d.sub.50 of an unagglomerated mixture of the same constituents used to form the agglomerated mineral composites.

16. The agglomerated mineral composite coating composition of claim 1, having an oil absorption ranging between about 50% and about 200%.

17. A method of making a coating composition having agglomerated mineral composites, the method comprising: adding a first inorganic particulate material to a second inorganic particulate material to form a mixture; adding a binder to the mixture, wherein the binder facilitates agglomeration of the first inorganic particulate material to the second inorganic particulate material to form the agglomerated mineral composites; and adding the agglomerated mineral composites to a coating vehicle.

18. The method of claim 17, wherein the coating composition comprises not more than 10% by weight titanium dioxide relative to the coating composition.

19. The method of claim 17, wherein the first inorganic particulate material comprises a material chosen from the group consisting of diatomaceous earth, mica, and perlite.

20. The method of claim 17, wherein the second inorganic particulate material comprises a material chosen from the group consisting of an aluminosilicate, talc, and an alkali earth metal carbonate.

21-23. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 shows an exemplary agglomerated mineral composite including diatomaceous earth and calcium carbonate.

[0032] FIG. 2 shows an exemplary agglomerated mineral composite including diatomaceous earth and kaolin.

[0033] FIG. 3 shows an exemplary agglomerated mineral composite including kaolin and calcium carbonate.

[0034] FIG. 4 shows an exemplary agglomerated mineral composite including perlite and calcium carbonate.

[0035] FIGS. 5 and 6 show exemplary agglomerated mineral composites including perlite and kaolin.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0036] According to some exemplary embodiments, agglomerated mineral composites may be added to coating compositions, such as, for example, paints, sealants, architectural coatings, and industrial coatings. The agglomerated mineral composites may include binary agglomerated mineral composites. Agglomeration may be facilitated through the use of a binder, such as, for example, sodium silicate.

[0037] Although certain embodiments of this disclosure may tend to discuss the agglomerated mineral composites in terms of diatomaceous earth, perlite, kaolin, and calcium carbonate, it will be understood that the invention should not be construed as being limited to such embodiments. Similarly, although certain embodiments of this disclosure may tend to discuss the binder in terms of sodium silicate, it will also be understood that the invention should not be construed as being limited to such embodiments.

[0038] In some cases, the properties of a coating may be more accurately governed by relative volume of fillers or additives relative to other coating components, rather than relative weight of the fillers or additives. One parameter in the design of coatings, such as paint, includes pigment volume concentration (PVC). PVC may be defined as a percentage of the volume of pigment and other non-volatile constituents, V.sub.pigment, relative the total composition of the dried coating, V.sub.total, which is V.sub.pigment plus the volume of the paint vehicle or resin:

% PVC=100V.sub.pigment/V.sub.total.

[0039] Another useful parameter for analyzing coating compositions is the critical pigment volume concentration (CPVC). The CPVC may be defined as the PVC where air interfaces develop in the dry coating because the coating composition is deficient in binder with respect to the pigments. For example, there may be insufficient binder to coat all of the pigments and bind all of the pigment to the paint vehicle or resin. Many coating volume properties may change drastically at the CPVC, due to incomplete binding. For example, the deficiency in binder can lead to increased porosity and decreased scrub-resistance. An increase oil-absorption may also increase the porosity of the dry coating.

[0040] Typically, the relationship between PVC and CPVC may depend upon the composition of the pigments and may be nonlinear. Because of this relationship, different coatings or paints may be more properly compared by using the reduced pigment volume concentration (RPVC), which is the ratio of PVC over CPVC. Thus, the RPVC can be defined as:

RPVC=PVC/CPVC.

[0041] When the RPVC for two coatings is equal, it is believed that a comparison of the coatings is more accurate.

[0042] High PVC coatings, such as, for example, interior paints, may have an RPVC greater than 1. These coatings may be formulated with smaller amounts of emulsion binder, and thus, the CPVC is lower than the PVC. When the RPVC is greater than 1, not all of the pigment or filler particles are covered by the emulsion binder in the dry coating. As a result, the dry coating may exhibit increased porosity. This increased porosity may be due to air entrapment during the coalescing stage of the coating drying process. Without wishing to be bound by a particular theory, it is believed that high-PVC coatings, such as those with an RPVC greater than 1, provide poor scrub-resistance. The scrub-resistance may be measured by standard methods, such as ASTM D2486 (Scrub Resistance of Paint Walls).

[0043] The agglomerated mineral composites may include a first inorganic particulate material and a second inorganic particulate material. The first inorganic particulate material may include diatomaceous earth, mica, feldspar, palygorskite, nepheline syenite, silica, attapulgite clay, perlite, an aluminosilicate (e.g., kaolin), talc, or an alkali earth metal carbonate (e.g., calcium carbonate, barium carbonate, or magnesium carbonate). The second inorganic particulate material may include diatomaceous earth, mica, feldspar, palygorskite, nepheline syenite, silica, attapulgite clay, perlite, an aluminosilicate (e.g., kaolin or bentonite), talc, or an alkali earth metal carbonate (e.g., calcium carbonate, barium carbonate, or magnesium carbonate). The calcium carbonate may include one or more of precipitated calcium carbonate (PCC), ground calcium carbonate (GCC), dolomite, limestone, chalk, and marble. Generally, the first inorganic particulate material and the second inorganic particulate material are different materials.

[0044] A binder may be used to facilitate agglomeration of the second inorganic particulate material to the first inorganic particulate material. For example, in some embodiments, the binder may be an alkali silica binder. The binder may include an alkali metal silicate.

[0045] According to some embodiments, the binder may include at least one of an inorganic binder, an organic binder, or an organic-to-inorganic binder. According to some embodiments, the binder may include an inorganic binder, such as an alkali metal silicate, such as, for example, sodium silicate, potassium silicate, and mixtures thereof. According to some embodiments, the inorganic binder may include a cement, such as a calcium aluminate cement. In some embodiments, the inorganic binder may include a cement, such as a calcium phosphate cement, and/or a magnesium phosphate cement. In some embodiments, the inorganic binder may include a magnesium aluminum silicate clay. According to some embodiments, the binder may include an organic-to-inorganic binder, such as a silicone or ethyl silicate.

[0046] According to some embodiments, the binder may include one or more organic binders or biopolymers. For example, the binder may include a cellulose, polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), starch, Candalilla wax, a polyacrylate or related copolymer (e.g., acrylic acid-acrylamide, etc.), a polydiallyldimethylammonium chloride polymer or copolymer (pDADMAC, etc.), dextrin, lignosulfonate, sodium alginate, magnesium stearate, and/or mixtures thereof.

[0047] Agglomeration of the first and second inorganic particulate materials may include using a binder to promote any appropriate agglomeration processes now known to the skilled artisan or hereafter discovered. For example, in some embodiments, agglomeration may include preparing an aqueous solution of the binder, and contacting the binder solution with a blend of the first and second inorganic particulate materials. One or more agglomerations may be performed, for example, when multiple binders, multiple first inorganic particulate materials, and/or multiple second inorganic particulate materials are used. The binder may also improve the adhesion and mechanical strength between components of the agglomerated mineral composites.

[0048] In some embodiments, contacting the binder solution with the blend of inorganic particulate materials may include mixing the binder solution with the blend of inorganic particulate materials. In some embodiments, the mixing may include agitation. In some embodiments, the blend of the first and second inorganic particulate materials and the binder solution is mixed sufficiently to at least substantially uniformly distribute the binder solution among the agglomeration points of contact of the first and second inorganic particulate materials. In some embodiments, the blend of the first and second inorganic particulate materials and the binder solution may be mixed with sufficient agitation to at least substantially uniformly distribute the binder solution among the agglomeration points of contact of the blend of first and second inorganic particulate materials without damaging the structure of the first or second inorganic particulate materials. In some embodiments, the contacting may include low-shear mixing.

[0049] In some embodiments, mixing may occur for about one hour. In other embodiments, mixing may occur for less than about one hour. In further embodiments, mixing may occur for about 30 minutes. In yet other embodiments, mixing may occur for about 20 minutes. In still further embodiments, mixing may occur for about 10 minutes.

[0050] In some embodiments, mixing may occur at about room temperature (i.e., from about 20 C. to about 23 C.). In other embodiments, mixing may occur at a temperature ranging from about 20 C. to about 50 C. In further embodiments, mixing may occur at a temperature ranging from about 30 C. to about 45 C. In still other embodiments, mixing may occur at a temperature of from about 35 C. to about 40 C.

[0051] According to some embodiments, contacting may include spraying the blend of first and second inorganic particulate materials with a binder solution. In some embodiments, the spraying may be intermittent. In other embodiments, the spraying may be continuous. In further embodiments, spraying includes mixing the blend of the first and second inorganic particulate materials while spraying with a binder solution, for example, to expose different agglomeration points of contacts to the spray. In some embodiments, such mixing may be intermittent. In other embodiments, such mixing may be continuous.

[0052] In some embodiments, the binder may be present in the binder solution in an amount less than about 40% by weight, relative to the weight of the binder solution. In some embodiments, the binder may range from about 1% to about 10% by weight. In further embodiments, the binder may range from about 1% to about 5% by weight.

[0053] An aqueous solution of the binder may be prepared with water. In some embodiments, the water is deionized water. In some embodiments, the water is ultrapure water. In further embodiments, the water has been treated to remove or decrease the levels of metals, toxins, and/or other undesirable elements before it is contacted with the binder.

[0054] The amount of aqueous solution contacted with the blend of the first and second inorganic particulate materials may range from about 0.25 parts to about 1.5 parts of aqueous solution to one part blend. In some embodiments, about 1 part aqueous solution is contacted with about 1 part blend.

[0055] The binder facilitates agglomeration of the second inorganic particulate material to the first inorganic particulate material. According to some embodiments, the second inorganic particulate material has a smaller diameter than the first inorganic particulate material. Without wishing to be bound by a particular theory, when the first and second inorganic particulate materials form agglomerations, it is believed that the second particulate material attaches to the first particulate material and fills interstitial voids between the agglomerated particles. It is believed that by filling these voids, the porosity of the dried coating may be reduced, thereby increasing the scrub-resistance of the coating, even when the RPVC is greater than 1, such as, for example, greater than 1.5, greater than 2.0, greater than 2.5, greater than 3.0, greater than 3.5, or greater than 4.0. By filling the interstitial voids between the particles, the oil-absorption of the coating may also decrease.

[0056] According to some embodiments, the ratio of the first inorganic particulate material to the second inorganic particulate material (first:second) may range from about 10:90 to about 90:10 by weight, for example, from about 20:80 to about 80:20 by weight, about 25:75 to 75:25 by weight, about 40:60 to about 60:40 by weight, or about 50:50 by weight.

[0057] Particle size characteristics described herein may be measured via sedimentation of the particulate material in a fully dispersed condition in an aqueous medium using a Sedigraph 5100 particle size analyzer, supplied by Micromeritics Instruments Corporation, Norcross, Ga., USA. The Sedigraph 5100 provides measurements and a plot of the cumulative percentage by weight of particles having a size, referred to in the art as the equivalent spherical diameter, or esd.

[0058] The particle size characteristics of diatomaceous earth and the agglomerated mineral composites may be measured by a Microtrac laser particle size distribution analyzer.

[0059] According to some embodiments, the agglomerated mineral composites may have a top particle size (d.sub.90) of less than about 100 m, such as, for example, less than about 90 m, less than about 80 m, less than about 70 m, less than about 60 m, less than about 55 m, less than about 50 m, less than about 45 m, less than about 40 m, less than about 35 m, less than about 30 m, less than about 25 m, or less than about 20 m.

[0060] According to some embodiments, the agglomerated mineral composites may have a median particle size (d.sub.50) of less than about 50 m, such as, for example, less than about 40 m, less than about 30 m, less than about 25 m, less than about 20 m, less than about 15 m, less than about 10 m, less than about 5 m, or less than about 3 m. According to some embodiments, the agglomerated mineral composite may have a median particle size (d.sub.50) ranging from about 1 m to about 50 m, such as, for example, from about 5 m to about 30 m, from about 10 m to about 30 m, from about 15 m to about 25 m, from about 20 m to about 30 m, from about 3 m to about 15 m, from about 5 m to about 15 m, from about 5 m to about 10 m, or from about 3 m to about 5 m.

[0061] According to some embodiments, the agglomerated mineral composites may have a bottom particle size (d.sub.10) of less than about 20 m, such as, for example, less than about 15 m, less than about 10 m, less than about 5 m, less than about 3 m, less than about 1 m, or less than about 0.5 m. According to some embodiments, the agglomerated mineral composite may have a bottom particle size (d.sub.10) ranging from about 0.5 m to about 20 m, such as, for example, from about 10 m to about 20 m, from about 5 m to about 15 m, from about 5 m to about 10 m, from about 0.5 m to about 5 m, from about 0.5 m to about 3 m, from about 3 m to about 5 m, from about 1 m to about 3 m, or from about 0.5 m to about 1 m.

[0062] According to some embodiments, the d.sub.90 and/or d.sub.50 of the agglomerated mineral composites may be substantially similar to the d.sub.90 and/or d.sub.50 of an unagglomerated mixture of the same constituents used to form the agglomerated mineral composites.

[0063] According to some embodiments, an agglomerated mineral composite including diatomaceous earth and calcium carbonate may have a d.sub.90 of less than about 100 m, such as, for example, less than about 90 m, less than about 80 m, less than about 70 m, less than about 60 m, less than about 55 m, less than about 50 m, less than about 45 m, less than about 40 m, less than about 35 m, less than about 30 m, less than about 25 m, or less than about 20 m. According to some embodiments, the agglomerated mineral composite including diatomaceous earth and calcium carbonate may have a median particle size (d.sub.50) of less than about 50 m, such as, for example, less than about 40 m, less than about 30 m, less than about 25 m, less than about 20 m, less than about 15 m, less than about 10 m, less than about 5 m, or less than about 3 m. According to some embodiments, the agglomerated mineral composite including diatomaceous earth and calcium carbonate may have a d.sub.50 ranging from about 1 m to about 50 m, such as, for example, from about 5 m to about 30 m, from about 10 m to about 30 m, from about 15 m to about 25 m, from about 20 m to about 30 m, from about 3 m to about 15 m, from about 5 m to about 15 m, from about 5 m to about 10 m, or from about 3 m to about 5 m.

[0064] According to some embodiments, the agglomerated mineral composites including diatomaceous earth and calcium carbonate may have a bottom particle size (d.sub.10) of less than about 20 m, such as, for example, less than about 15 m, less than about 10 m, less than about 5 m, less than about 3 m, less than about 1 m, or less than about 0.5 m. According to some embodiments, the agglomerated mineral composites including diatomaceous earth and calcium carbonate may have a bottom particle size (d.sub.10) ranging from about 0.5 m to about 20 m, such as, for example, from about 10 m to about 20 m, from about 5 m to about 15 m, from about 5 m to about 10 m, from about 0.5 m to about 5 m, from about 0.5 m to about 3 m, from about 3 m to about 5 m, from about 1 m to about 3 m, or from about 0.5 m to about 1 m.

[0065] The d.sub.90 and/or d.sub.50 of the agglomerated mineral composite including diatomaceous earth and calcium carbonate may be substantially similar to the d.sub.90 and/or d.sub.50 of an unagglomerated mixture of the same diatomaceous earth and calcium carbonate.

[0066] According to some embodiments, an agglomerated mineral composite including perlite and calcium carbonate may have a d.sub.90 of less than about 100 m, such as, for example, less than about 90 m, less than about 80 m, less than about 70 m, less than about 60 m, less than about 55 m, less than about 50 m, less than about 45 m, less than about 40 m, less than about 35 m, less than about 30 m, less than about 25 m, or less than about 20 m. According to some embodiments, the agglomerated mineral composite including perlite and calcium carbonate may have a d.sub.50 of less than about 50 m, such as, for example, less than about 40 m, less than about 30 m, less than about 25 m, less than about 20 m, less than about 15 m, less than about 10 m, less than about 5 m, or less than about 3 m. According to some embodiments, the agglomerated mineral composite including perlite and calcium carbonate may have a median particle size (d.sub.50) ranging from about 1 m to about 50 m, such as, for example, from about 5 m to about 30 m, from about 10 m to about 30 m, from about 15 m to about 25 m, from about 20 m to about 30 m, from about 3 m to about 15 m, from about 5 m to about 15 m, from about 5 m to about 10 m, or from about 3 m to about 5 m. According to some embodiments, the agglomerated mineral composites including perlite and calcium carbonate may have a bottom particle size (d.sub.10) of less than about 20 m, such as, for example, less than about 15 m, less than about 10 m, less than about 5 m, less than about 3 m, less than about 1 m, or less than about 0.5 m. According to some embodiments, the agglomerated mineral composites including perlite and calcium carbonate may have a bottom particle size (d.sub.10) ranging from about 0.5 m to about 20 m, such as, for example, from about 10 m to about 20 m, from about 5 m to about 15 m, from about 5 m to about 10 m, from about 0.5 m to about 5 m, from about 0.5 m to about 3 m, from about 3 m to about 5 m, from about 1 m to about 3 m, or from about 0.5 m to about 1 m

[0067] The d.sub.90 and/or d.sub.50 of the agglomerated mineral composite including perlite and calcium carbonate may be substantially similar to the d.sub.90 and/or d.sub.50 of an unagglomerated mixture of the same perlite and calcium carbonate.

[0068] According to some embodiments, an agglomerated mineral composite including diatomaceous earth and kaolin may have a top particle size (d.sub.90) of less than about 100 m, such as, for example, less than about 90 m, less than about 80 m, less than about 70 m, less than about 60 m, less than about 55 m, less than about 50 m, less than about 45 m, less than about 40 m, less than about 35 m, less than about 30 m, less than about 25 m, or less than about 20 m. According to some embodiments, the agglomerated mineral composite including diatomaceous earth and kaolin may have a median particle size (d.sub.50) of less than about 50 m, such as, for example, less than about 40 m, less than about 30 m, less than about 25 m, less than about 20 m, less than about 15 m, less than about 10 m, less than about 5 m, or less than about 3 m. According to some embodiments, the agglomerated mineral composite including diatomaceous earth and kaolin may have a median particle size (d.sub.50) ranging from about 1 m to about 50 m, such as, for example, from about 5 m to about 30 m, from about 10 m to about 30 m, from about 15 m to about 25 m, from about 20 m to about 30 m, from about 3 m to about 15 m, from about 5 m to about 15 m, from about 5 m to about 10 m, or from about 3 m to about 5 m. According to some embodiments, the agglomerated mineral composites including diatomaceous earth and kaolin may have a bottom particle size (d.sub.10) of less than about 20 m, such as, for example, less than about 15 m, less than about 10 m, less than about 5 m, less than about 3 m, less than about 1 m, or less than about 0.5 m. According to some embodiments, the agglomerated mineral composites including diatomaceous earth and kaolin may have a bottom particle size (d.sub.10) ranging from about 0.5 m to about 20 m, such as, for example, from about 10 m to about 20 m, from about 5 m to about 15 m, from about 5 m to about 10 m, from about 0.5 m to about 5 m, from about 0.5 m to about 3 m, from about 3 m to about 5 m, from about 1 m to about 3 m, or from about 0.5 m to about 1 m

[0069] The d.sub.90 and/or d.sub.50 of the agglomerated mineral composite including diatomaceous earth and kaolin may be substantially similar to the d.sub.90 and/or d.sub.50 of an unagglomerated mixture of the same diatomaceous earth and kaolin.

[0070] According to some embodiments, an agglomerated mineral composite including perlite and kaolin may have a d.sub.90 of less than about 100 m, such as, for example, less than about 90 m, less than about 80 m, less than about 70 m, less than about 60 m, less than about 55 m, less than about 50 m, less than about 45 m, less than about 40 m, less than about 35 m, less than about 30 m, less than about 25 m, or less than about 20 m. According to some embodiments, the agglomerated mineral composite including perlite and kaolin may have a d.sub.50 of less than about 50 m, such as, for example, less than about 40 m, less than about 30 m, less than about 25 m, less than about 20 m, less than about 15 m, less than about 10 m, less than about 5 m, or less than about 3 m. According to some embodiments, the agglomerated mineral composite including perlite and kaolin may have a median particle size (d.sub.50) ranging from about 1 m to about 50 m, such as, for example, from about 5 m to about 30 m, from about 10 m to about 30 m, from about 15 m to about 25 m, from about 20 m to about 30 m, from about 3 m to about 15 m, from about 5 m to about 15 m, from about 5 m to about 10 m, or from about 3 m to about 5 m. According to some embodiments, the agglomerated mineral composites including perlite and kaolin may have a bottom particle size (d.sub.10) of less than about 20 m, such as, for example, less than about 15 m, less than about 10 m, less than about 5 m, less than about 3 m, less than about 1 m, or less than about 0.5 m. According to some embodiments, the agglomerated mineral composites including perlite and kaolin may have a bottom particle size (d.sub.10) ranging from about 0.5 m to about 20 m, such as, for example, from about 10 m to about 20 m, from about 5 m to about 15 m, from about 5 m to about 10 m, from about 0.5 m to about 5 m, from about 0.5 m to about 3 m, from about 3 m to about 5 m, from about 1 m to about 3 m, or from about 0.5 m to about 1 m.

[0071] The d.sub.90 and/or d.sub.50 of the agglomerated mineral composite including perlite and kaolin may be substantially similar to the d.sub.90 and/or d.sub.50 of an unagglomerated mixture of the same perlite and kaolin.

[0072] According to some embodiments, an agglomerated mineral composite including kaolin and calcium carbonate may have a d.sub.90 of less than about 100 m, such as, for example, less than about 90 m, less than about 80 m, less than about 70 m, less than about 60 m, less than about 55 m, less than about 50 m, less than about 45 m, less than about 40 m, less than about 35 m, less than about 30 m, less than about 25 m, or less than about 20 m. According to some embodiments, the agglomerated mineral composite including kaolin and calcium carbonate may have a d.sub.50 of less than about 50 m, such as, for example, less than about 40 m, less than about 30 m, less than about 25 m, less than about 20 m, less than about 15 m, less than about 10 m, less than about 5 m, or less than about 3 m. According to some embodiments, the agglomerated mineral composite including kaolin and calcium carbonate may have a median particle size (d.sub.50) ranging from about 1 m to about 50 m, such as, for example, from about 5 m to about 30 m, from about 10 m to about 30 m, from about 15 m to about 25 m, from about 20 m to about 30 m, from about 3 m to about 15 m, from about 5 m to about 15 m, from about 5 m to about 10 m, or from about 3 m to about 5 m. According to some embodiments, the agglomerated mineral composites including kaolin and calcium carbonate may have a bottom particle size (d.sub.10) of less than about 20 m, such as, for example, less than about 15 m, less than about 10 m, less than about 5 m, less than about 3 m, less than about 1 m, or less than about 0.5 m. According to some embodiments, the agglomerated mineral composites including kaolin and calcium carbonate may have a bottom particle size (d.sub.10) ranging from about 0.5 m to about 20 m, such as, for example, from about 10 m to about 20 m, from about 5 m to about 15 m, from about 5 m to about 10 m, from about 0.5 m to about 5 m, from about 0.5 m to about 3 m, from about 3 m to about 5 m, from about 1 m to about 3 m, or from about 0.5 m to about 1 m.

[0073] The d.sub.90 of the agglomerated mineral composite including kaolin and calcium carbonate may be larger than the d.sub.90 of an unagglomerated mixture of the same kaolin and calcium carbonate. The d.sub.50 of the agglomerated mineral composite including kaolin and calcium carbonate may be substantially similar to the d.sub.50 of an unagglomerated mixture of the same kaolin and calcium carbonate.

[0074] According to some embodiments, a coating composition including agglomerated mineral composites may have an oil absorption ranging between about 50% and about 200%, such as, for example, between about 50% and about 150%, between about 50% and about 100%, between about 70% and about 90%, between about 100% and about 200%, between about 100% and about 150%, between about 120% and about 140%, between about 120% and about 130%, between about 150% and about 200%, between about 150% and about 170%, between about 150% and about 160%, or between about 155% and about 165%. The oil absorption of the coating composition having agglomerated mineral composites may be lower than the oil absorption of a coating composition including an unagglomerated mixture of the same constituents used to form the agglomerated mineral composites.

[0075] According to some embodiments, a coating composition including agglomerated mineral composites including kaolin and calcium carbonate may have an oil absorption ranging between about 20% and about 100%, such as, for example, between about 50% and about 100%, between about 70% and about 90%, or between about 75% and 85%. The oil absorption of the coating composition including agglomerated mineral composite including kaolin and calcium carbonate may be higher than the oil absorption of a similar composition containing a mixture of kaolin and calcium carbonate in an unagglomerated form.

[0076] According to some embodiments, a coating composition including agglomerated mineral composite including diatomaceous earth and calcium carbonate may have an oil absorption ranging between about 75% and about 150%, such as, for example, between about 100% and about 150%, or between about 120% and about 130%. The oil absorption of an agglomerated mineral composite including diatomaceous earth and calcium carbonate may be lower than the oil absorption of a similar composition containing a mixture of diatomaceous earth and calcium carbonate in an unagglomerated form.

[0077] According to some embodiments, a coating composition including agglomerated mineral composite including perlite and calcium carbonate may have an oil absorption ranging between about 75% and about 150%, such as, for example, between about 100% and about 150%, or between about 120% and about 130%. The oil absorption of a coating composition including agglomerated mineral composite including perlite and calcium carbonate may be lower than the oil absorption of a similar composition containing a mixture of perlite and calcium carbonate in an unagglomerated form.

[0078] According to some embodiments, a coating composition including agglomerated mineral composite including diatomaceous earth and kaolin may have an oil absorption ranging between about 100% and about 200%, such as, for example, between about 125% and about 175%, between about 150% and about 170%, or between about 155% and about 165%. The oil absorption of a coating composition including agglomerated mineral composite including diatomaceous earth and kaolin may be lower than the oil absorption of a similar composition containing a mixture of diatomaceous earth and kaolin in an unagglomerated form.

[0079] According to some embodiments, a coating composition including agglomerated mineral composite including perlite and kaolin may have an oil absorption ranging between about 100% and about 200%, such as, for example, between about 125% and about 175%, between about 150% and about 170%, or between about 150% and about 160%. The oil absorption of a coating composition including agglomerated mineral composite including perlite and kaolin may be lower than the oil absorption of a similar composition containing a mixture of perlite and kaolinin an unagglomerated form.

[0080] According to some exemplary embodiments, the agglomerated mineral composites may enhance the opacity of dry coatings containing a low level of titanium dioxide (TiO.sub.2). For example, a coating composition may contain less than about 10% TiO.sub.2, such as, for example, less than about 8% TiO.sub.2, less than about 6% TiO.sub.2, less than about 4% TiO.sub.2, less than about 2% TiO.sub.2, or about 0% TiO.sub.2 (e.g., substantially-free of TiO.sub.2).

[0081] According to some embodiments, a coating composition containing agglomerated mineral composites may have a Hunter L value greater than about 90. For example, the coating composition containing agglomerated mineral composites may have a Hunter L value greater than about 92, greater than about 93, greater than about 94, greater than about 95, greater than about 96, greater than about 97, or greater than about 98.

[0082] According to some embodiments, a coating composition containing agglomerated mineral composites may have a Hunter a value between about 0.5 and 0.5. For example, the coating composition containing agglomerated mineral composites may have a Hunter a value between about 0.5 and 0, between about 0.3 and 0.1, between about 0.2 and 0.0, between about 0.1 and 0.1, between about 0 and 0.5, between about 0 and 0.3, between about 0 and 0.1, between about 0.2 and 0.3, or between about 0.3 and 0.4.

[0083] According to some embodiments, a coating composition containing agglomerated mineral composites may have a Hunter b value less than about 5. For example, the coating composition containing agglomerated mineral composites may have a Hunter b value less than about 4, less than about 3.5, less than about 3.3, less than about 3, less than about 2.5, less than about 2.4, less than about 2.3, less than about 2.2, less than about 2, less than about 1.9, less than about 1.7, less than about 1.5, less than about 1.3, less than about 1.2, or less than about 1.1.

[0084] According to some embodiments, a coating composition containing agglomerated mineral composites may have an opacity greater than about 80%. The opacity may be measured using a Datacolor 550 Spectrophotometer with QC input software and using Leant 2B drawdowns, a Peopac Form 1B card, with film thicknesses of 3 mils (75 microns) and 6 mils (150 microns). For example, a coating composition containing agglomerated mineral composites may have an opacity greater than about 85%, greater than about 87%, greater than about 88%, greater than about 90%, greater than about 92%, greater than about 93%, or greater than about 95%. An opacity of 0% represents a material that is completely transparent, while an opacity of 100% represents a material that is completely opaque.

[0085] Although the embodiments below are generally discussed with respect to paint compositions, it is understood that the principles disclosed herein are applicable to various other forms of coatings.

Example 1

[0086] Table 1 below shows an exemplary 73% PVC paint composition. Two samples were prepared with this composition: a control composition and an agglomerated mineral composite composition. The control paint composition includes fine calcined kaolin, diatomaceous earth (DE, natural grade), and calcium carbonate (CaCO.sub.3, d.sub.50=7 microns). The control composition also includes titanium dioxide (TiO.sub.2) and vinyl acrylic emulsion binder. The control paint composition includes 27% volume solids and less than 100 g/l volatile organic compounds (VOC).

[0087] The exemplary agglomerated mineral composite paint composition having agglomerated mineral composites is similar to the control composition, except that the calcined kaolin and DE minerals were agglomerated by the addition of 5% by weight sodium silicate as a binder with 10% by weight water. The percent of sodium silicate (e.g., binder) and water was measured relative to the total weight of the other components of the agglomerated mineral composites (e.g., 5 g sodium silicate per 100 g DE and kaolin). The DE and kaolin were first mixed using a blender. Sodium silicate was added to the mixture to promote agglomeration. The agglomerated samples were then dried and screened through a 150 mesh screen for proper Hegman dispersion of the paint. The agglomerated particles were then added to a paint formulation to create the exemplary paint compositions.

[0088] The PVC is 73% based on the total solids volume of 27% (VOC 87 g/l). The CPVC for the exemplary sample is 24%. Therefore the RPVC for the exemplary sample composition is 3.04.

TABLE-US-00001 TABLE 1 Exemplary Paint Compositions Raw Materials Vol. (gal) Amt. (lbs) % Water 51.6 430.5 38.7 Nuosept 95 0.3 3.0 0.3 Natrosol Plus 330 0.1 1.5 0.1 Water 9.0 75.0 6.7 Propylene Glycol 1.7 15.0 1.3 DrewPlus L-475 0.4 3.0 0.3 Tamol 731A 1.0 9.0 0.8 AMP 95 0.2 1.5 0.1 Triton CF 10 0.5 4.5 0.4 TiO.sub.2 1.5 50.0 4.5 Kaolin 9.2 201.0 18.1 Diatomaceous Earth 5.4 99.0 8.9 CaCO.sub.3 (7 m) 3.3 75.0 6.7 Encor 300 13.5 120.0 10.8 Texanol 1.5 12.0 1.1 Acrysol RM-825 1.4 12.0 1.1 Total 100.6 1112.0 100.0

[0089] Table 2 below shows various performance properties for the sample paint compositions of Table 1. Scrub-resistance was measured by ASTM D2486 using a 7-mil side-by-side wet paint film thickness on a Leneta scrub test panel substrate. The wet side-by-side paint films were kept at room temperature for seven days. The Gardco washability and wear tester, manufactured by Paul N. Gardner Company, was used to perform the scrub-resistance test.

TABLE-US-00002 TABLE 2 Performance Properties Sample A (Aggregated Properties Control 1 Composite) Viscosity KU @ 25 C. 111 105 Density (lbs./gal.) 11.26 11.13 Contrast Ratio @ 3.0 mils 99.5 99.5 Contrast Ratio @ 6.0 mils 99.9 99.9 Reflectance 91.8 90.7 Whiteness 80.6 80.3 Yellowness 4.5 4.2 Hunter L 95.8 95.2 Hunter b 2.4 2.3 Gloss @ 60 unsealed 2.6 2.6 Sheen @ 85 unsealed 12.8 9.6 Scrub-resistance (ASTM D2486) 65 175

[0090] As can be seen in Table 2, almost all of the properties for the paint composition with the agglomerated mineral composites are comparable to the control composition, except that the scrub-resistance for the aggregated composite sample is nearly three times greater than the control sample. Accordingly, it is believed that the agglomeration of mineral composites may yield desirable increases in properties, such as scrub-resistance, without adversely affecting certain other properties, such as whiteness or reflectance.

Example 2

[0091] Table 3 below shows the general composition for another exemplary paint composition of a second control sample having a PVC of 71 with 29% volume of solids.

TABLE-US-00003 TABLE 3 Exemplary Paint Composition Raw Materials Vol. (gal) Amt. (lbs) % Water 54.0 450.0 39.0 Nuosept 95 0.3 3.0 0.3 Natrosol Plus 330 0.4 5.0 0.4 Water 4.8 40.0 3.5 Propylene Glycol 1.2 10.0 0.9 DrewPlus L-475 0.6 4.5 0.4 Tamol 731A 1.1 10.0 0.9 Triton CF 10 0.6 5.0 0.4 AMP 95 0.1 0.5 0.4 TiO.sub.2 1.5 50.0 4.4 CaCO.sub.3 (7 m) 3.7 85.0 7.5 Kaolin 13.6 297.0 26.1 Diatomaceous Earth 1.8 33.0 2.9 Encor 300 14.6 130.0 11.4 Texanol 0.9 7.0 0.6 Acrysol RM 825 1.2 10.0 0.9 Total 100.2 1140.0 100.0

[0092] Additional samples containing agglomerated mineral composites of diatomaceous earth and kaolin were prepared with varying amounts of sodium silicate binder and water by weight based on the total weight of the DE and kaolin. These additional compositions are substantially similar to the composition shown in Table 3, except that the DE and kaolin are agglomerated rather than dispersed. The various binder and water amounts for each sample are shown below in Table 4.

TABLE-US-00004 TABLE 4 Agglomerated Mineral Composites Sample Control 2 (Table 3) B C D E F G H I % H.sub.20 0% 5% 5% 5% 5% 10% 10% 10% 10% % Na 0% 1% 2% 3% 4% 1% 2% 3% 4% Silicate

[0093] Table 5 below shows various properties of each of agglomerated mineral composite samples B-I, as compared with the second control sample having non-agglomerated minerals.

TABLE-US-00005 TABLE 5 Properties of Agglomerated Mineral Composite Compositions Property Control 2 B C D E F G H I Viscosity KU @ 25 C. 107 122 113 1.9 108 114 109 103 108 Contrast Ratio @ 3.0 mils 99.2 99.3 99.4 99.2 99.4 99.3 99.2 99.3 99.2 Contrast Ratio @ 6.0 mils 99.9 99.9 99.9 99.9 99.9 99.9 99.9 99.9 99.9 Reflectance 93.5 93.4 93.5 93.4 93.3 93.6 93.5 93.5 93.4 Whiteness 89.5 89.4 89.4 89.3 89.3 89.5 89.4 89.4 89.4 Yellowness 3.6 3.5 3.6 3.6 3.6 3.7 3.7 3.7 3.6 Hunter L 96.9 96.8 96.8 96.8 96.7 96.9 96.8 96.8 96.8 Hunter b 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 Gloss @ 60 unsealed 2.7 2.7 2.7 2.7 2.7 2.8 2.8 2.8 2.8 Sheen @ 85 unsealed 21.6 21.2 20.2 19.8 18.9 24.9 24.6 23.6 20.8 Oil-Absorption (%) 124 128 122 121 114 116 124 128 127 Scrub-Resistance 49 57 75 126 244 53 66 85 235

[0094] As shown in Table 5, the agglomerated mineral composite compositions have similar properties to the control composition (e.g., Hunter L, contrast ratios), except that the scrub-resistance increases with increasing amounts of sodium silicate binder to facilitate agglomeration of the mineral composites. For example, the scrub-resistance at 4% sodium silicate, with either 5% water or 10% water, is almost five times the scrub-resistance of the control composition.

Example 3

[0095] Table 6 shows several exemplary particle size comparisons for agglomerated mineral composite samples. Table 6 also compares the Hunter L, a, and b values of the mineral composites with their individual constituents, as well as comparing the values for both the mixed (e.g., non-agglomerated) particles and the agglomerated particles. Sodium silicate was used to agglomerate the various constituent minerals.

TABLE-US-00006 TABLE 6 Agglomerated Mineral Composites Sample Type Oil- Wet Mineral Mineral absorption Density d.sub.10 d.sub.50 d.sub.90 Hunter Hunter A B (%) (lb/cf) (m) (m) (m) L b Control Perlite N/A 259 12 11.45 25.88 50.92 93.57 4.91 Control DE N/A 268 15 5.12 13.11 28.50 93.22 4.88 Control Calcined N/A 138 39 0.44 2.10 10.47 97.09 2.05 kaolin Control CaCO.sub.3 N/A 32 78 0.83 3.45 9.58 97.29 0.53 Mixed Calcined CaCO.sub.3 68 42 0.55 2.47 9.98 97.85 1.76 kaolin Agglomerated Calcined CaCO.sub.3 81 42 0.76 3.31 22.15 96.85 1.68 kaolin Mixed DE CaCO.sub.3 141 26 2.19 9.98 24.73 94.28 4.12 Agglomerated DE CaCO.sub.3 125 25 1.56 8.41 24.48 94.37 3.40 Mixed Perlite CaCO.sub.3 131 18 7.32 23.79 49.19 93.51 2.03 Agglomerated Perlite CaCO.sub.3 126 19 7.55 24.53 58.27 95.04 1.85 Mixed DE Calcined 183 23 1.44 9.46 23.97 94.88 4.35 kaolin Agglomerated DE Calcined 160 22 1.29 8.25 25.58 95.04 3.13 kaolin Mixed Perlite Calcined 172 18 7.04 23.91 49.47 93.73 2.69 kaolin Agglomerated Perlite Calcined 156 22 6.92 23.46 48.33 94.57 2.24 kaolin

[0096] As shown in Table 6, when fine particles, such as kaolin and calcium carbonate, are mixed or agglomerated with larger particles, such as perlite or diatomaceous earth, the particle sizes (e.g., d.sub.10, d.sub.50, and d.sub.90) generally remain close to the same as the pure large particle size. As also shown in Table 6, oil-absorption decreases when the composite particles are agglomerated, as compared with mixed particles or purely large particles. Without wishing to be bound by a particular theory, it is believed that when small particles, such as kaolin or calcium carbonate, are agglomerated with larger particles, such as diatomaceous earth or perlite, the small particles fill the interstitial pores between the large particles, thereby inhibiting oil-absorption.

[0097] As also shown in Table 6, when small particles are agglomerated, the agglomerated particle size generally increases. For example, Table 6 shows that when kaolin and calcium carbonate are agglomerated, the d.sub.90 particle size increases from about 9.98 m to about 22.15 m. Without wishing to be bound by a particular theory, when small particles are agglomerated, such as kaolin and calcium carbonate, the larger agglomerated particle size may increase oil-absorption as compared with the mixed particles alone.

[0098] FIGS. 1-6 show exemplary agglomerated mineral composites. FIG. 1 shows an exemplary agglomerated mineral composite including diatomaceous earth and calcium carbonate. FIG. 2 shows an exemplary agglomerated mineral composite including diatomaceous earth and kaolin. FIG. 3 shows an exemplary agglomerated mineral composite including kaolin and calcium carbonate. FIG. 4 shows an exemplary agglomerated mineral composite including perlite and calcium carbonate. FIGS. 5 and 6 show exemplary agglomerated mineral composites including perlite and kaolin.

[0099] In the examples above, according to some embodiments, the calcined kaolin may include fine grade calcined kaolin, such as marketed under the trade name NEOGEN (e.g., NEOGEN 2000) or POLESTAR (e.g., POLESTAR 400P) calcined kaolin, marketed by Imerys Performance Minerals. The kaolin may include calcined kaolin, such as marketed by Imerys Pigments under the trade names ALPHATEX or ALPHATEX HP, or by Imerys Minerals Ltd. under the trade name SUPREME. According to some embodiments, the diatomaceous earth may include natural grade diatomaceous earth, such as marketed by World Minerals, Inc., under the trade name CELTIX. According to some embodiments, the TiO.sub.2 may be pigment-grade TiO.sub.2, such as marketed by DuPont under the trade name TI-PURE (e.g., TI-PURE R-706). According to some embodiments, the calcium carbonate may include ground calcium carbonate, such as marketed by Imerys Performance Minerals under the trade names DRIKALITE or ATOMITE, or marketed by Imerys Minerals Ltd. under the trade name CARBITAL. According to some embodiments, the perlite may include perlite for additives, such as marketed by Imerys Filtration Minerals under the trade name OPTIMAT.

[0100] Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the exemplary embodiments disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.