Reflective granular composition containing cristobalite

Abstract

The present disclosure relates to a reflective granular composition comprising a reflective pigment material including cristobalite; and at least 5 wt. % of a hardener, based on the total solids weight of the composition. The present disclosure also relates to a building material containing the reflective granular composition. The present disclosure also relates to a method for making the reflective granular composition.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Application No. 63 / 415,119, filed October 11, 2022, the entire disclosure of which is incorporated herein by reference. [Background technology]

[0002] The present disclosure relates to reflective granular compositions containing cristobalite and methods for making the same.

[0003] Commercial and residential roofs are often continually exposed to harsh or extreme external factors. Even when external conditions are mild, these roofs are exposed to environmental or weather conditions that affect their ability to insulate the interior of the building or home from the effects of those environmental or weather conditions. In many parts of the world, roofs are constantly exposed to hot, sunny conditions during the summer months, under which roofing materials absorb solar energy and retain high heat. As roofs absorb solar energy and retain heat, conditions within the building or home below deteriorate, often resulting in overheated and uncomfortable interiors.

[0004] To improve these conditions, buildings and homes often increase the amount of interior insulation or the use of artificial cooling systems (e.g., HVAC equipment). However, there is a limit to the ability of increased insulation to reduce heat transfer, and increasing energy costs make the increased use of artificial cooling systems undesirable and, in some cases, cost-prohibitive. Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore desirable to provide a roof that is more resistant to temperature increases caused by incident solar radiation. [Means for solving the problem]

[0006] (overview) The present disclosure relates to a reflective granular composition comprising a reflective pigment material including cristobalite, and at least 5 wt. % of a hardening agent, based on the total solids weight of the composition. The hardening agent may include, for example, a sodium salt.

[0007] In some non-limiting embodiments, the reflective pigment material comprises cristobalite. In such embodiments, the composition contains at least 50 wt. % cristobalite, based on the total solids weight of the composition. For example, the composition can contain cristobalite in an amount selected from the range of 50 wt. % to 95 wt. % based on the total solids weight of the composition. The composition can also contain a curing agent in an amount selected from the range of 5 wt. % to 40 wt. % based on the total solids weight of the composition.

[0008] In one non-limiting embodiment, the cristobalite has a d90 selected from the range of 1 μm to 40 μm. The reflective granular composition can also have a particle size selected from the range of 8 mesh to 40 mesh.

[0009] In some non-limiting embodiments, the reflective pigment material further comprises a secondary pigment component selected from the group consisting of kaolin clay, metal and transition metal oxides, alkaline earth metal sulfates, alkaline earth metal carbonates, transition metal silicates, minerals, and mixtures thereof, hi some non-limiting embodiments, the compounds exhibit a total solar reflectance of at least 70%.

[0010] The present disclosure also relates to building materials containing the aforementioned reflective granular compositions. In one non-limiting embodiment, the building materials include roofing materials.

[0011] The present disclosure further provides a method of preparing a reflective granular composition, comprising the steps of mixing quartz sand and water together to form a slurry; adding and mixing a hardening agent to the slurry; granulating and / or drying the slurry; firing the resulting material to form a sintered material comprising cristobalite and the hardening agent; and crushing and sieving the sintered material to form a reflective granular composition having a desired particle size.

[0012] In some non-limiting embodiments, the calcination is carried out at a temperature of 900° C. to 1500° C. In one non-limiting embodiment, the sintered material is crushed and sieved to form a reflective granular composition having a particle size selected within the range of 8 mesh to 40 mesh. The curing agent, reflective pigment material, and other ingredients previously and further described herein can be used in methods for preparing various compositions.

[0013] In certain non-limiting embodiments, a method of preparing a reflective granular composition includes mixing cristobalite and a hardening agent together to form a reflective granular composition. The method can further include grinding and sieving the reflective granular composition to have a desired particle size, such as a particle size selected within the range of 8 mesh to 40 mesh. In some non-limiting embodiments, the hardening agent includes a sodium salt.

[0014] The present disclosure also relates to the following items:

[0015] Item 1: A reflective granular composition comprising: a reflective pigment material comprising cristobalite; and at least 5 wt. % of a hardener, based on the total solids weight of the composition.

[0016] Item 2: The reflective granular composition of item 1, wherein the hardening agent comprises a sodium salt.

[0017] Item 3: The reflective granular composition according to item 1 or 2, wherein the reflective pigment material is composed of cristobalite.

[0018] Item 4: The reflective granular composition of item 3, wherein the composition contains at least 50% by weight of cristobalite, based on the total solids weight of the composition.

[0019] Item 5: The reflective granular composition according to Item 4, wherein the composition contains cristobalite in an amount selected within the range of 50% by weight to 95% by weight based on the total solids weight of the composition.

[0020] Item 6: The reflective granular composition according to any one of items 1 to 5, wherein the composition contains a curing agent in an amount selected from the range of 5% by weight to 40% by weight based on the total solids weight of the composition.

[0021] Item 7: The reflective granular composition according to any one of items 1 to 6, wherein the cristobalite has a d90 selected in the range of 1 μm to 40 μm.

[0022] Item 8: The reflective granular composition according to any one of items 1 to 7, wherein the reflective granular composition has a particle size selected within the range of 8 mesh to 40 mesh.

[0023] Item 9: The reflective granular composition according to any one of items 1, 2, and 6-8, wherein the reflective pigment material further comprises a secondary pigment component selected from the group consisting of kaolin clay, metal and transition metal oxides, alkaline earth metal sulfates, alkaline earth metal carbonates, transition metal silicates, minerals, and mixtures thereof.

[0024] Item 10: The reflective granular composition of any one of items 1 to 9, wherein the compound exhibits a total solar reflectance of at least 70%.

[0025] Item 11: A building material containing the reflective granular composition according to any one of items 1 to 10.

[0026] Item 12: The building material according to Item 11, wherein the building material comprises a roofing material.

[0027] Item 13: A method for preparing a reflective granular composition, the method comprising the steps of mixing quartz sand and water together to form a slurry; adding and mixing a hardening agent to the slurry; granulating and / or drying the slurry; firing the resulting material to form a sintered material comprising cristobalite and the hardening agent; and crushing and sieving the sintered material to form a reflective granular composition having a desired particle size.

[0028] Item 14: The method according to Item 13, wherein the firing is carried out at a temperature of 900°C to 1500°C.

[0029] Item 15: The method of items 13 or 14, wherein the sintered material is crushed and sieved to form a reflective granular composition having a particle size selected within the range of 8 mesh to 40 mesh.

[0030] Item 16: The method of any one of items 13 to 15, wherein the curing agent comprises a sodium salt.

[0031] Item 17: The method of any one of items 13 to 16, wherein the reflective pigment material of the reflective granular composition is composed of cristobalite.

[0032] Item 18: The method of any one of items 13 to 16, wherein the reflective pigment material further comprises a secondary pigment component selected from the group consisting of kaolin clay, metal and transition metal oxides, alkaline earth metal sulfates, alkaline earth metal carbonates, transition metal silicates, minerals, and mixtures thereof.

[0033] Item 19: A method of preparing a reflective granular composition, the method comprising mixing cristobalite and a hardener together to form the reflective granular composition.

[0034] Item 20: The method of item 19, further comprising milling and sieving the reflective granular composition to have a desired particle size.

[0035] Item 21: The method according to item 20, wherein the reflective granular composition is crushed and sieved to a particle size selected within the range of 8 mesh to 40 mesh.

[0036] (Detailed explanation) For purposes of the following detailed description, it is understood that the invention can assume various alternative modifications and step sequences unless expressly stated otherwise. Furthermore, unless otherwise indicated in the operating examples or otherwise indicated, all numerical values ​​in the specification and claims, for example, expressing the amounts of ingredients used, are understood to be modified in all instances by the term "about." Accordingly, unless otherwise indicated, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending upon the desired properties obtained by the present invention. At the very least, the application of the doctrine of equivalents is not intended to be a limitation on the scope of the claims, and each numerical parameter should, at the very least, be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0037] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible, however, any numerical value inherently contains certain errors necessarily resulting from the standard deviation in their respective testing measurements.

[0038] It should also be understood that the numerical ranges set forth herein are intended to encompass all subranges encompassed within that range. For example, a range of "1 to 10" is intended to encompass all subranges between the stated minimum value of 1 and maximum value of 10 (inclusive), i.e., any subrange with a minimum value of 1 or greater and a maximum value of 10 or less.

[0039] In this application, the use of the singular includes the plural and the plural includes the singular, unless specifically stated otherwise. Furthermore, in this application, although "and / or" is expressly used in certain instances, the use of "or" means "and / or" unless specifically stated otherwise. Furthermore, in this application, the use of "a" or "an" means "at least one" unless specifically stated otherwise.

[0040] As used herein, the transition term "comprising" (and similar terms such as "containing" and "including") is "open-ended" and may include unspecified materials. While described with the term "comprising," the terms "consisting essentially of" and "consisting of" are also within the scope of this disclosure.

[0041] As used herein, terms such as "granular roofing material," "particulate roofing material," and the like refer to solar-reflecting particles or granules useful in so-called "cool roof" applications, and these terms are used interchangeably with terms such as "solar-reflecting particles," "solar-reflecting granules," "reflective particles," and "reflective granules." Furthermore, while the particles and granules described herein are described in terms of their effectiveness in "cool roof" applications, it is understood that the described particles and granules may have other uses and applications, and that the described embodiments are not limited to use in "cool roof" applications. For example, in some non-limiting embodiments, the particulate roofing materials described herein may be useful on any exterior surface, such as, for example, as a filler in exterior paints.

[0042] In one non-limiting embodiment, the reflective granular composition contains a reflective pigment material comprising cristobalite; and a curing agent. As used herein, "cristobalite" refers to a crystalline polymorph of silica. The cristobalite used to form the reflective pigment material can have a particle structure with a d90 particle size selected within a range of 1 μm to 40 μm, or 1 μm to 30 μm, or 3 μm to 20 μm, or 5 μm to 10 μm, such as 5 μm or 10 μm. As used herein, "d90 particle size" refers to the average diameter of a particle sample in which 90% by weight of the particles have a size smaller than a given d90 value. The d90 particle size is measured by sieving through stacked U.S. Standard test sieves.

[0043] The cristobalite in the reflective granular composition can function as a reflective pigment that exhibits high reflectivity at specific wavelengths of solar radiation reaching the earth's surface. When the reflective granular composition is applied to the surface of an object placed in an outdoor environment, the cristobalite can reflect at least a portion of the solar radiation incident on the object, thereby reducing the temperature rise of the object due to the incident solar radiation (by the object absorbing less solar radiation and reflecting more solar radiation compared to the same object coated with the same composition without the cristobalite).

[0044] In some non-limiting embodiments, the reflective pigment material may include at least one secondary pigment component. For example, the secondary pigment component may include additional pigment materials and / or pigment additives. Some non-limiting examples of suitable secondary pigment components include metal and transition metal oxides (e.g., TiO, ZnO, SnO, and various titanates), alkaline earth metal sulfates (e.g., BaSO, MgSO (including anhydrous or hydrated forms, such as Epsom salts)), alkaline earth metal carbonates (e.g., SrCO and BaCO), transition metal silicates (e.g., ZrSiO), and minerals. For example, in some non-limiting embodiments, the secondary pigment component may include kaolin clay.

[0045] In some non-limiting embodiments, the composition contains at least 50 wt% cristobalite, or at least 60 wt% cristobalite, or at least 70 wt% cristobalite, based on the total solids weight of the composition. The composition can also contain up to 95 wt% cristobalite, or up to 90 wt% cristobalite, or up to 80 wt% cristobalite, based on the total solids weight of the composition. For example, the composition can contain an amount of cristobalite selected from the ranges of 50 wt% to 95 wt%, or 60 wt% to 95 wt%, or 70 wt% to 95 wt%, based on the total solids weight of the composition.

[0046] In some non-limiting embodiments, when a secondary pigment component is used, the cristobalite may comprise at least 5% by weight, or at least 10% by weight, of the reflective granular composition, based on the total solids weight of the composition. When a secondary pigment component is used, the cristobalite may comprise up to 50% by weight, or up to 40% by weight, or up to 30% by weight, or up to 20% by weight, or up to 15% by weight, based on the total solids weight of the reflective granular composition. In some non-limiting embodiments, when a secondary pigment component is used, the composition contains an amount of cristobalite selected from the range of 5% to 20% by weight, or 10% to 20% by weight, based on the total solids weight of the reflective granular composition.

[0047] As mentioned above, the reflective granular composition may also contain, for example, kaolin clay. The type or source of the kaolin clay is not particularly limited. Non-limiting examples of kaolin clay materials include EPK Kaolin available from Edgar Minerals (Edgar, FL) (e.g., having an Fe content of about 0.93 wt. %, where the reported Fe content is adjusted to exclude loss on ignition (LOI) and normalized to a total oxide content of 100%), MCNAMEE Kaolin available from Vanderbilt Minerals, LLC (Norwalk, CT) (e.g., having an Fe content of about 0.38 wt. %, where the reported Fe content is adjusted to exclude LOI and normalized to a total oxide content of 100%), Kingsley Kaolin available from Kentucky-Tennessee Clay Company (Roswell, GA) (e.g., having an Fe content of 0.45 wt. %, where the reported Fe content is adjusted to exclude LOI and normalized to a total oxide content of 100%), and 6 TILE Kaolin available from Kentucky-Tennessee Clay Company (Roswell, GA). Examples of suitable kaolin clays include kaolin (e.g., having an Fe content of about 0.4% by weight, with the reported Fe content adjusted to exclude LOI and normalized to a total oxide content of 100%), optiKasT Kaolin available from Kentucky-Tennessee Clay Company (Roswell, Georgia) (e.g., having an Fe content of about 0.58% by weight, with the reported Fe content adjusted to exclude LOI and normalized to a total oxide content of 100%), and Ione Airfloated Kaolin available from Ione Minerals, Inc. (Ione, California) (e.g., having an Fe content of about 0.7% by weight, with the reported Fe content adjusted to exclude LOI and normalized to a total oxide content of 100%). The kaolin clay may include calcined kaolin clay.

[0048] When used in the reflective granular composition, the kaolin clay and the secondary pigment can function as an additional highly solar-reflecting component in addition to cristobalite. The kaolin clay can have high reflectivity at specific wavelengths of solar radiation reaching the Earth's surface. The kaolin clay can have reflectivity at the same or different wavelengths of solar radiation compared to the kaolin clay. Kaolin clay can be particularly effective at reflecting specific ultraviolet (UV) wavelengths of solar radiation. When the reflective granular composition is applied to the surface of an object placed outdoors, the kaolin clay can reflect at least a portion of the solar radiation incident on the object, thereby reducing the temperature rise of the object due to incident solar radiation (by the object absorbing less solar radiation and reflecting more solar radiation compared to the same object coated with the same composition without kaolin clay).

[0049] In certain non-limiting embodiments, the reflective granular composition, when using kaolin clay, can contain at least 50% or at least 55% by weight of kaolin clay, based on the total solids weight of the reflective granular composition. The reflective granular composition, when using kaolin clay, can contain up to 70% or up to 60% by weight of kaolin clay, based on the total solids weight of the reflective granular composition. In some non-limiting embodiments, when using kaolin clay, the composition contains an amount of kaolin clay selected from the range of 50% to 70% by weight, or 60% to 70% by weight, based on the total solids weight of the reflective granular composition.

[0050] It is understood that the reflective granular composition may contain, in addition to cristobalite, one or any combination of the aforementioned secondary pigment components.

[0051] In one non-limiting embodiment, the reflective pigment material is formed solely from cristobalite, i.e., in one non-limiting embodiment, 100% by weight of the reflective pigment material is composed solely of cristobalite and does not contain any of the aforementioned secondary pigment components.

[0052] The reflective granular composition may contain an effective amount of cristobalite and, optionally, one or more secondary pigment components to exhibit a bulk total solar reflectance (also referred to herein as "total solar reflectance" (TSR) or simply "solar reflectance") of at least 70%, such as at least 80% or at least 85%, as measured using a reflectometer from Surface Optics Corporation (San Diego, California). The reflective granular composition may exhibit a TSR of 70-90%, 80-90%, 70-95%, or 80-95%. For example, a 410-Solar visible / NIR Portable Reflectometer from Surface Optics Corporation (San Diego, California) may be used, which measures reflectance over seven wavelength bands and uses an algorithm to calculate the TSR.

[0053] The reflective granular composition can contain an effective amount of cristobalite and, optionally, one or more secondary pigment components to exhibit a UV reflectance of at least 20%, such as 20% to 80% (e.g., in the 335-380 nm wavelength band). In some non-limiting embodiments, the reflective granular composition can exhibit a UV reflectance of at least 25%, such as 25% to 75%, 25% to 70%, or 40% to 70%, when measured using a solar reflectance meter manufactured by Surface Optics Corporation (San Diego, California). For example, in some non-limiting embodiments, the reflective granular composition can exhibit a UV reflectance of at least 50%, such as 50% to 70%, when measured using a solar reflectance meter manufactured by Surface Optics Corporation (San Diego, California).

[0054] The reflective granular composition can contain an effective amount of cristobalite and, optionally, one or more secondary pigment components to exhibit a visible light ("VIS") reflectance (e.g., in the 400-720 nm wavelength band) of at least 60%, such as 60%-97%, or 60%-95%, when measured using a solar reflectance meter from Surface Optics Corporation (San Diego, Calif.). For example, in some non-limiting embodiments, the reflective granular composition can exhibit a VIS reflectance of at least 70%, such as 70%-98% or 70%-97%, when measured using a solar reflectance meter from Surface Optics Corporation (San Diego, Calif.).

[0055] The reflective granular composition can contain an effective amount of cristobalite and, optionally, one or more secondary pigment components to exhibit an infrared ("IR") reflectance (e.g., in the 700-2500 nm wavelength band) of at least 60%, such as 60%-98%, or 60%-97%, when measured using a solar reflectance meter from Surface Optics Corporation (San Diego, Calif.). For example, in some non-limiting embodiments, the granular composition can exhibit an IR reflectance of at least 70%, such as 70%-98% or 70%-97%, when measured using a solar reflectance meter from Surface Optics Corporation (San Diego, Calif.).

[0056] As noted, the reflective granular composition also includes a hardening agent. As used herein, "hardening agent" refers to an additive that improves the strength of the resulting reflective granular composition. The materials that form the hardening agent may also provide other benefits, such as helping to act as a binder. "Binder" refers to a component material that helps hold all of the components that make up the composition together.

[0057] Non-limiting examples of hardening agents that can be used to form the reflective granular composition include sodium silicate, sodium salts such as sodium hydroxide, or combinations thereof. Further non-limiting examples of suitable sodium silicates include potassium silicate, potassium sodium silicate, other metasilicates known in the art, or combinations thereof. Further non-limiting examples of hardening agents include sodium carbonate, sodium chloride, sodium polyacrylate, sodium sulfate, sodium thiosulfate, sodium phosphate, or mixtures thereof.

[0058] In some non-limiting embodiments, the hardening agent (e.g., sodium silicate) comprises at least 5 wt.%, or at least 10 wt.%, or at least 15 wt.%, of the composition, based on the total solids weight of the composition. The hardening agent (e.g., sodium silicate) may comprise up to 40 wt.%, or up to 30 wt.%, or up to 25 wt.%, or up to 20 wt.%, of the composition, based on the total solids weight of the composition. In some non-limiting embodiments, the composition contains an amount of hardening agent selected from the range of 5 wt.% to 40 wt.%, or 5 wt.% to 30 wt.%, or 5 wt.% to 15 wt.%, based on the total solids weight of the composition.

[0059] Additionally, materials that function as pure binder materials can be added to improve the consistency and adhesion of particles within the slurry. Suitable binder materials include a group of water-soluble polymers, such as water-soluble synthetic polymers. Water-soluble synthetic polymers may contain hydrophilic functional groups such as ethers, alcohols, amides, and pyrrolidones. In some non-limiting embodiments or aspects, the binder material may include polyvinyl alcohol.

[0060] In one non-limiting embodiment, the method for preparing the reflective granular composition includes the steps of: mixing quartz sand and water together to form a slurry; adding and mixing a hardening agent to the slurry; granulating and / or drying the slurry; firing the resulting material to form a sintered material containing cristobalite and the hardening agent; and crushing and sieving the sintered material to form a reflective granular composition having a desired particle size. It is understood that the granulated and / or dried slurry is fired to convert the quartz sand to cristobalite. It is understood that the quartz sand can include coarse sand, fine sand, whole sand, crushed sand, or any combination thereof.

[0061] As previously described, quartz sand is mixed with water and a hardening agent to form a slurry. The slurry may form a substantially homogeneous mixture. As used herein, the term "substantially" is used as a term of approximation, not as a term of degree, and is intended to account for inherent deviations and variations in measured, observed, or calculated properties or values. Thus, the term "substantially homogeneous" indicates that a mixture may not be completely homogeneous, but would be considered homogeneous by one of ordinary skill in the art.

[0062] In some non-limiting embodiments, the method of forming the slurry can include adding a liquid medium (e.g., water) to the mixture of ingredients until a desired consistency is achieved. The desired consistency at this stage of the process can vary depending on various factors, such as whether the final composition is desired to be moldable or flowable. However, in some non-limiting embodiments, the liquid medium can be added to the particulate mixture in an amount of 20 to 50 wt%, such as 30 to 40 wt%, based on the total weight of the slurry mass. For example, in some non-limiting embodiments in which the composition is desired to be moldable, the liquid medium can be added to the particulate mixture in an amount of 20 to 40 wt%, such as 25 to 35 wt%, or 25 to 30 wt%, based on the total weight of the slurry mass. In some non-limiting embodiments where it is desired that the composition be flowable, the liquid medium can be added to the particulate mixture in an amount of 30 to 50 wt %, such as 35 to 45 wt % or 35 to 40 wt %, based on the total weight of the slurry mass.

[0063] The slurry can then be processed into granules. In some non-limiting embodiments, the method can further include extruding the slurry or spray-granulating the slurry, and / or then, optionally, drying the extruded or sprayed product. The drying can be carried out at any temperature suitable for substantially removing the liquid medium. As mentioned above, as used herein, the term "substantially" is a term of approximation, not a term of degree, and the phrase "substantially removing the liquid medium" is intended to take into account inherent variations in measuring, calculating, or observing the amount of liquid medium remaining in the mixture after drying. For example, as will be understood by those skilled in the art, the liquid medium is considered to be substantially removed when the amount of liquid medium remaining in the mixture is undetectable or negligible.

[0064] The temperature for drying the slurry is not particularly limited and can vary depending on the liquid medium selected. However, the temperature should be high enough to substantially remove the liquid medium, but not high enough to constitute a heat treatment or calcination procedure. For example, drying can be carried out at a temperature of 100°C to 800°C, such as 100°C to 700°C, 120°C to 160°C, 130°C to 150°C, or 100°C to 130°C. The time required to dry the wet mixture is also not particularly limited and can vary depending on the consistency of the wet mixture, the liquid medium used in the wet mixture, the temperature used to carry out the drying, and the amount of liquid medium in the wet mixture. In some non-limiting embodiments, drying is carried out for 10 minutes to 90 minutes, such as 20 minutes to 70 minutes, or 30 minutes to 60 minutes.

[0065] The dry mixture can be ground and / or calcined (or heat-treated). In embodiments in which the dry mixture is ground and calcined, the dry mixture can be first ground and then calcined, or first calcined and then ground. In some non-limiting embodiments, the dry mixture can be first ground (before calcining) to the desired particle size using a grinder and a sieve of the desired size. This pre-grinding allows fines (or particulates) to be reintroduced into the production feed, thereby reducing the amount of waste generated by the process. The particulates generated during the grinding process can be recycled by being reintroduced into the production feed. However, due to their small particle size, the amount of liquid medium required to achieve the desired consistency of the wet mixture may increase. In some non-limiting embodiments, the recycled particulates can be added to the production feed in an amount of 25% or less by weight of the material.

[0066] As noted above, according to some non-limiting embodiments, the dry mixture can be calcined before or after grinding. The calcining process can be carried out at any suitable temperature and for any suitable time. For example, in some non-limiting embodiments, the dry mixture (either before or after grinding) can be calcined (or baked) at a temperature of 800°C or 900°C to 1500°C, such as 1000°C to 1300°C, 1025°C to 1275°C, or 1050°C to 1250°C. Furthermore, in some non-limiting embodiments, the dry mixture can be calcined (or baked) for 30 minutes to 90 minutes, e.g., 45 minutes to 75 minutes, 50 minutes to 70 minutes, or 60 minutes. As noted above, the calcining process is carried out to bond the quartz sand particles and convert the quartz sand to cristobalite.

[0067] In some non-limiting embodiments, the resulting granules have a viscosity of 50 lbs / ft 3 ~75lbs / ft 3 , 40 lbs / ft 3 ~60lbs / ft 3 , 50lbs / ft 3 ~60lbs / ft 3 , or 45 lbs / ft 3 ~60lbs / ft 3 40 lbs / ft 3 ~75lbs / ft 3 In some non-limiting embodiments, the resulting granular particulate composition may have a bulk density of 52 lbs / ft 3 ~58lbs / ft 3 , or 53 lbs / ft 3 ~56lbs / ft 3 50 lbs / ft 3 ~60lbs / ft 3 The particulate composition may have a bulk density of about 1000 MPa. The relatively low bulk density of the particulate composition may allow for significant cost savings. For example, a low bulk density may allow for a lower amount of particles (or granules) to be applied per unit area (or unit square), while still providing solar reflectance benefits (e.g., high total solar reflectance and / or UV, VIS, and / or IR reflectance).

[0068] The reflective granular composition can be coated or treated with a compound, such as a clear treatment or clear coating compound, to coat or treat the surface of the granules. Such compounds include, but are not limited to, at least one of silanes, siloxanes, polysiloxanes, organosiloxanes, silicates, organosilicates, silicone resins, acrylics, urethanes, polyurethanes, glycol ethers, and mineral oils. Exemplary coatings, surface treatments, and methods for coating and treating particles are shown and described in U.S. Patent No. 7,241,500, U.S. Patent No. 3,479,201, U.S. Patent No. 3,255,031, U.S. Patent No. 3,208,571, and U.S. Patent Application Publication No. 2020 / 0308413, all of which are incorporated herein by reference in their entireties. Coatings applied to granules can enhance the protection of the granules against asphalt fouling.

[0069] To maintain the high solar reflectance of the granules, the coating and / or surface treatment should be applied in a manner that does not significantly reduce the reflectance of the granules. For example, many suitable coatings and / or surface treatments include sealants or other clear coatings that do not adversely affect the overall solar reflectance of the granules. In some non-limiting embodiments, the granules may be treated with an emulsion of silanes and siloxanes without the addition of a solvent. In another embodiment, the granules may be treated with SILRES BS3003, available from Wacker Chemi AG (Munich, Germany).

[0070] The surface treatment and / or coating can be applied to the granules using various methods and processes known to those skilled in the art. For example, in one exemplary embodiment, after the raw material is ground, sieved to a preferred sieve size, and packaged, the particles can be treated by adding the particles to an aqueous solution to fully saturate the particles with the treatment agent, and then immediately drying at a temperature not exceeding 600°F (316°C) to remove excess moisture. In another exemplary embodiment, after the raw material is ground, sieved to a preferred sieve size, and packaged, the particles can be post-treated by spraying the particles with an aqueous solution, and then immediately drying at a temperature not exceeding 600°F (316°C) to remove excess moisture. In yet another exemplary embodiment, after the raw material is ground and sieved to a preferred sieve size, the particles can be sprayed with an aqueous solution, and then immediately kiln-dried at a temperature not exceeding 600°F (316°C) to remove excess moisture, and then packaged. In yet another embodiment of coating and / or treating the surface of granules, after the raw material has been milled and screened to a preferred sieve size, the particles can be sprayed with an aqueous solution, then immediately aerated to remove excess water, and then packaged. The coating and / or surface treatment can be applied as delivered (e.g., off-the-shelf) or as an aqueous dilution. Dilution ratios can range from 1:5 to 1:200. The dilution can be prepared from demineralized water.

[0071] In one non-limiting embodiment, the reflective granular composition is crushed and screened to have a particle size selected from the range of 8 mesh to 40 mesh.

[0072] In one non-limiting embodiment, the method of preparing the reflective granular composition includes mixing cristobalite and a hardener (as described above) together to form a reflective granular composition, the method further including crushing and sieving the reflective granular composition to have a desired particle size, such as a particle size selected from the range of 8 mesh to 40 mesh.

[0073] The reflective granular composition (e.g., untreated or treated) can be used to form building materials. The building materials can include roofing or other building materials. The building materials can be placed in an outdoor environment.

[0074] The roofing material can be formed by applying the reflective granular composition to an asphalt layer. The asphalt layer can include bitumen or modified bitumen modified with at least one reinforcing material, such as polyester or glass fiber. Such a roofing material, in which the reflective granular composition is applied to an asphalt layer, can constitute a cool roof system. [Example]

[0075] The following examples are presented to illustrate the general principles of the present disclosure. The present disclosure should not be considered limited to the specific examples presented. All parts and percentages in the examples are by weight unless otherwise specified.

[0076] Example 1 (Preparation of Reflective Granular Composition) A reflective granular composition was prepared by first mixing 600 g of dry quartz sand (Min-U-Sil® 10, manufactured by US Silica) with a D90 of 10 μm in water. Next, 60 g of a 50% concentration sodium silicate solution (N®, manufactured by PQ Corporation) was added to the mixture, and water was added to adjust the final sand concentration to 50% to form the final slurry. This slurry was then dried at 100 °C overnight, after which the dried material was sintered by firing in a furnace at 1150 °C for 2 hours and then cooled to ambient temperature. The sintered material was crushed in a jaw crusher and sieved to particle sizes ranging from 8 mesh to 40 mesh to produce granules.

[0077] The TSR of the granules was measured using a Solar Spectrum Reflectometer Model SSR manufactured by Devices and Services, and was found to be 95.133.

[0078] Examples 2 to 6 (Preparation of Reflective Granular Composition) Reflective granular compositions were prepared using the same materials and steps as in Example 1, but with varying amounts of sodium silicate as shown in Table 1. The reflective granular compositions of Examples 2-6 all exhibited excellent TSR. [Table 1]

[0079] Example 7 (Preparation of Reflective Granular Composition) A reflective granular composition was prepared by first mixing 600 g of dry quartz sand (Min-U-Sil® 5, manufactured by US Silica) with a D90 of 5 μm in water. Next, 360 g of a 50% concentration sodium silicate solution (N®, manufactured by PQ Corporation) was added to the mixture, and water was added to adjust the final sand concentration to 50% to form the final slurry. This slurry was dried overnight at 100 °C, and then the dried material was sintered by firing in a furnace at 1150 °C for 2 hours and then cooled to ambient temperature. The sintered material was crushed in a jaw crusher and sieved to particle sizes ranging from 8 mesh to 40 mesh to produce granules.

[0080] The TSR of the granules was measured using a Solar Spectrum Reflectometer Model SSR manufactured by Devices and Services, and was found to be 91.17.

[0081] Those skilled in the art will readily appreciate that modifications may be made to the present invention without departing from the concepts disclosed in the foregoing description. Accordingly, the particular embodiments detailed herein are illustrative only and do not limit the scope of the invention, which extends to the full scope of the appended claims and any equivalents thereof.

Claims

1. 1. A reflective granular composition comprising: a reflective pigment material comprising cristobalite; and at least 5 wt. % of a curing agent, based on the total solids weight of the composition; A reflective granular composition comprising:

2. The reflective granular composition of claim 1 , wherein the hardening agent comprises a sodium salt.

3. The reflective granular composition of claim 1 wherein said reflective pigment material is comprised of cristobalite.

4. 4. The reflective granular composition of claim 3, wherein said composition contains at least 50% by weight of cristobalite, based on the total solids weight of said composition.

5. 5. The reflective granular composition of claim 4, wherein the composition contains cristobalite in an amount selected within the range of 50% to 95% by weight based on the total solids weight of the composition.

6. 10. The reflective granular composition of claim 1, wherein the composition contains a curing agent in an amount selected within the range of 5% to 40% by weight based on the total solids weight of the composition.

7. 2. The reflective granular composition of claim 1, wherein said cristobalite has a d90 selected within the range of 1 μm to 40 μm.

8. 10. The reflective granular composition of claim 1, wherein said reflective granular composition has a particle size selected within the range of 8 mesh to 40 mesh.

9. 10. The reflective granular composition of claim 1, wherein the reflective pigment material further comprises a secondary pigment component selected from the group consisting of kaolin clay, metal and transition metal oxides, alkaline earth metal sulfates, alkaline earth metal carbonates, transition metal silicates, minerals, and mixtures thereof.

10. 10. The reflective granular composition of claim 1, wherein said compound exhibits a total solar reflectance of at least 70%.

11. A building material comprising the reflective granular composition of claim 1.

12. 12. The building material of claim 11, wherein the building material comprises a roofing material.

13. 1. A method for preparing a reflective granular composition, comprising: mixing quartz sand and water together to form a slurry; adding a curing agent to the slurry and mixing; granulating and / or drying the slurry; firing the resulting material to form a sintered material comprising cristobalite and the curing agent; and grinding and sieving said sintered material to form a reflective granular composition having a desired particle size.

14. The method of claim 13, wherein the firing is carried out at a temperature of from 900°C to 1500°C.

15. 14. The method of claim 13, wherein the sintered material is crushed and sieved to form a reflective granular composition having a particle size selected within the range of 8 mesh to 40 mesh.

16. The method of claim 13 , wherein the curing agent comprises a sodium salt.

17. The method of claim 13 wherein the reflective pigment material of the reflective granular composition comprises cristobalite.

18. 14. The method of claim 13, wherein the reflective pigment material further comprises a secondary pigment component selected from the group consisting of kaolin clay, metal and transition metal oxides, alkaline earth metal sulfates, alkaline earth metal carbonates, transition metal silicates, metal silicates, minerals, and mixtures thereof.

19. 1. A method for preparing a reflective granular composition, comprising: mixing the cristobalite and the hardener together to form a reflective granular composition; A method comprising:

20. 20. The method of claim 19, further comprising crushing and sieving the reflective granular composition to have a desired particle size.

21. 21. The method of claim 20, wherein the reflective granular composition is crushed and sieved to a particle size selected within the range of 8 mesh to 40 mesh.

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