Reflective particulate composition containing cristobalite

Abstract

The present disclosure relates to a reflective particulate composition comprising: a reflective pigment material comprising cristobalite, and at least 5% by weight of a hardener, based on the total solids weight of the composition. The present disclosure also relates to a building material comprising the reflective particulate composition. The present disclosure also relates to a method of making the reflective particulate composition.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 415,119, filed on October 11, 2022. The entire disclosure thereof is incorporated herein by reference. Background Art Technical Field

[0003] This disclosure relates to a reflective granular composition containing cristobalite and a method for preparing the same.

[0004] Technical Considerations

[0005] Commercial and residential roofs are continuously exposed to external elements, which are often harsh or extreme. Even under moderate external conditions, these roofs are exposed to environmental or weather conditions that affect the roof's ability to insulate the interior of a building or residence from the effects of the environment or weather. In many parts of the world, during the summer months, roofs are continuously exposed to high heat and sunlight conditions, under which roof materials absorb solar energy and maintain a high level of heat. As the roof absorbs solar energy and retains heat, the conditions inside the underlying building or residence are adversely affected, often resulting in the interior warming to uncomfortable conditions.

[0006] To remedy these conditions, buildings or residences often resort to increasing amounts of internal insulation materials or increasing the use of artificial cooling systems (e.g., HVAC equipment). However, increasing the amount of insulation has a limited ability to reduce heat transfer, and the increased energy costs make the increased use of artificial cooling systems unsatisfactory or even cost - prohibitive.

[0007] Accordingly, there is a desire to provide roofs that are more resistant to temperature increases caused by incident solar radiation. Summary of the Invention

[0008] This disclosure relates to a reflective granular composition comprising: a reflective pigment material containing cristobalite; and at least 5 wt% of a hardener, based on the total solids weight of the composition. The hardener can include, for example, sodium salts.

[0009] In some non - limiting embodiments, the reflective pigment material consists of cristobalite. In such embodiments, the composition contains at least 50 wt% of cristobalite, based on the total solids weight of the composition. For example, the composition can contain an amount of cristobalite selected from the range of 50 wt% to 95 wt%, based on the total solids weight of the composition. The composition can also contain an amount of hardener selected from the range of 5 wt% to 40 wt%, based on the total solids weight of the composition.

[0010] In some non-limiting embodiments, cristobalite has a d selected from the range of 1 μm to 40 μm 90 . The reflective particles may also have a particle size selected from the range of 8 mesh to 40 mesh.

[0011] In some non-limiting embodiments, the reflective pigment material further comprises a minor pigment component selected from the group consisting of kaolin clay, metals and transition metal oxides, alkaline earth metal sulfates, alkaline earth metal carbonates, transition metal silicates, minerals, and mixtures thereof. In some non-limiting embodiments, the composition exhibits a total solar reflectance of at least 70%.

[0012] The present disclosure also relates to a building material comprising the above-described reflective granular composition. In some non-limiting embodiments, the building material comprises a roofing material.

[0013] The present disclosure further relates to a method for preparing a reflective granular composition, comprising: mixing quartz sand with water to form a slurry; adding a hardener to the slurry and mixing; granulating and / or drying the slurry; calcining the resulting material to form a sintered material comprising cristobalite and the hardener; and crushing and screening the sintered material to form a reflective granular composition having a desired particle size.

[0014] In some non-limiting embodiments, the calcination is carried out at a temperature of 900 °C to 1500 °C. In some non-limiting embodiments, the sintered material is crushed and screened to form a reflective granular composition having a particle size selected from the range of 8 mesh to 40 mesh. The above-described and further described hardener, reflective pigment material, and other components can be used in the method to prepare various compositions.

[0015] In some non-limiting embodiments, the method for preparing a reflective granular composition comprises mixing cristobalite and a hardener together to form a reflective granular composition. The method may further comprise crushing and screening 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. In some non-limiting embodiments, the hardener comprises a sodium salt.

[0016] The present disclosure also relates to the following clauses.

[0017] Clause 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.

[0018] Clause 2: The reflective granular composition according to Clause 1, wherein the hardener comprises a sodium salt.

[0019] Clause 3: The reflective granular composition according to Clause 1 or 2, wherein the reflective pigment material consists of cristobalite.

[0020] Clause 4: The reflective granular composition according to Clause 3, wherein the composition comprises at least 50% by weight of cristobalite, based on the total solids weight of the composition.

[0021] Clause 5: The reflective granular composition according to Clause 4, wherein the composition comprises an amount of cristobalite selected from the range of 50% to 95% by weight, based on the total solids weight of the composition.

[0022] Clause 6: The reflective granular composition according to any one of Clauses 1 - 5, wherein the composition comprises an amount of hardener selected from the range of 5% to 40% by weight, based on the total solids weight of the composition.

[0023] Clause 7: The reflective granular composition according to any one of Clauses 1 - 6, wherein the cristobalite has a d selected from the range of 1 μm to 40 μm 90 .

[0024] Clause 8: The reflective granular composition according to any one of Clauses 1 - 7, wherein the reflective particles have a particle size selected from the range of 8 mesh to 40 mesh.

[0025] Clause 9: The reflective granular composition according to any one of Clauses 1 - 2 and 6 - 8, wherein the reflective pigment material further comprises a minor pigment component selected from the group consisting of kaolin clay, metals and transition metal oxides, alkaline earth metal sulfates, alkaline earth metal carbonates, transition metal silicates, minerals, and mixtures thereof.

[0026] Clause 10: The reflective granular composition according to any one of Clauses 1 - 9, wherein the composition exhibits a total solar reflectance of at least 70%.

[0027] Clause 11: A building material comprising the reflective granular composition according to any one of Clauses 1 - 10.

[0028] Clause 12: The building material according to Clause 11, wherein the building material comprises a roofing material.

[0029] Clause 13: A method of preparing a reflective granular composition, comprising: mixing quartz sand with water to form a slurry; adding a hardener to the slurry and mixing; granulating and / or drying the slurry; calcining the resulting material to form a sintered material comprising cristobalite and the hardener; and crushing and screening the sintered material to form a reflective granular composition having a desired particle size.

[0030] Clause 14: The method according to Clause 13, wherein the calcination is carried out at a temperature of 900 °C to 1500 °C.

[0031] Clause 15: The method according to Clause 13 or 14, wherein the sintered material is crushed and screened to form a reflective granular composition having a particle size selected from the range of 8 mesh to 40 mesh.

[0032] Clause 16: The method according to any one of Clauses 13 - 15, wherein the hardening agent comprises a sodium salt.

[0033] Clause 17: The method according to any one of Clauses 13 - 16, wherein the reflective pigment material of the reflective granular composition consists of cristobalite.

[0034] Clause 18: The method according to any one of Clauses 13 - 16, wherein the reflective pigment material further comprises a secondary pigment component selected from the group consisting of kaolin clay, metals and transition metal oxides, alkaline earth metal sulfates, alkaline earth metal carbonates, transition metal silicates, minerals, and mixtures thereof.

[0035] Clause 19: A method for preparing a reflective granular composition, comprising: mixing cristobalite and a hardening agent together to form a reflective granular composition.

[0036] Clause 20: The method according to Clause 19, further comprising crushing and screening the reflective granular composition to have a desired particle size.

[0037] Clause 21: The method according to Clause 20, wherein the reflective granular composition is crushed and screened to a particle size selected from the range of 8 mesh to 40 mesh. Detailed Description

[0038] For the purposes of the following detailed description, it should be understood that, unless explicitly stated to the contrary, the present invention may assume various alternative variations and sequences of steps. Moreover, except where otherwise indicated in any operating examples or otherwise, all numbers expressing quantities of ingredients, for example used in the specification and claims of this application, are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the reported number of significant digits and by applying ordinary rounding techniques.

[0039] Although the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values recited in the specific examples are reported as precisely as possible. However, any numerical value inherently contains some error resulting from the standard variations in their respective testing measurements.

[0040] In addition, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, i.e., having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0041] In this application, the use of the singular includes the plural, and the plural encompasses the singular, unless specifically stated otherwise. In addition, in this application, the use of "or" means "and / or", unless specifically stated otherwise, even though in some cases "and / or" may be explicitly used. Further, in this application, the use of "a" or "an" means "at least one", unless specifically stated otherwise.

[0042] As used herein, the transitional term "comprising" (and other comparable terms such as "containing" and "including") is "open-ended" and open to the inclusion of unspecified materials. Although described in terms of "comprising", the terms "consisting essentially of" and "consisting of" are also within the scope of the invention.

[0043] As used herein, the terms "granular roofing material", "particulate roofing material" and like terms refer to solar reflective granules or particles useful in so-called "cool roof" applications, and these terms are used interchangeably with the terms "solar reflective granule", "solar reflective particle", "reflective granule", "reflective particle" and like terms. In addition, although the granules and particles described herein are described in terms of their efficacy in "cool roof" applications, it should be understood that the granules and particles may have other uses and applications, and the embodiments are not limited to use in "cool roof" applications. For example, in some non-limiting embodiments, the granular roofing materials described herein may be useful on any outer surface, such as as a filler in an exterior coating, or similar applications.

[0044] In some non-limiting embodiments, the reflective granular composition comprises: a reflective pigment material comprising cristobalite; and a hardener. As used herein, "cristobalite" refers to a crystalline polymorph of silica. The cristobalite used to form the reflective pigment material may have a particulate structure having a d 90 particle size selected from 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, "d 90"Particle size" means the average diameter of a sample of particles in which 90% by weight of the particles have a size smaller than a given d 90 value. The d 90 particle size is determined by sieving with a stack of United States standard test sieves.

[0045] The cristobalite in the reflective granular composition can act as a reflective pigment that is highly reflective at some wavelengths of solar radiation reaching the Earth's surface. When the reflective granular composition is disposed on the surface of an object placed under outdoor conditions, the cristobalite can reflect at least a portion of the solar radiation incident on the object to reduce the temperature rise of the object caused by the incident solar radiation (by the object absorbing less and reflecting more solar radiation compared to the same object coated with the same composition without cristobalite).

[0046] In some non-limiting embodiments, the reflective pigment material can include at least one secondary pigment component. For example, the secondary pigment component can include additional pigment materials and / or pigment additives. Some non-limiting examples of suitable secondary pigment components include metals and transition metal oxides (such as TiO2, ZnO, SnO, and various titanates), alkaline earth metal sulfates (such as BaSO4, MgSO4 (including anhydrous or hydrated forms, e.g., Epsom salts)), alkaline earth metal carbonates (such as SrCO3 and BaCO3), transition metal silicates (such as ZrSiO4), and minerals. For example, in some non-limiting embodiments, the secondary pigment component can include kaolin clay.

[0047] In some non-limiting embodiments, the composition comprises at least 50% by weight of cristobalite, or at least 60% by weight of cristobalite, or at least 70% by weight of cristobalite, based on the total solids weight of the composition. The composition can also comprise up to 95% by weight of cristobalite, or up to 90% by weight of cristobalite, or up to 80% by weight of cristobalite, based on the total solids weight of the composition. For example, the composition can comprise an amount of cristobalite selected from the range of 50% to 95% by weight, or 60% to 95% by weight, or 70% to 95% by weight, based on the total solids weight of the composition.

[0048] In some non-limiting embodiments, when a minor pigment component is used, cristobalite may be at least 5 wt%, or at least 10 wt%, based on the total solids weight of the reflective particulate composition. When a minor pigment component is used, cristobalite may also be at most 50 wt%, or at most 40 wt%, or at most 30 wt%, or at most 20 wt%, or at most 15 wt%, based on the total solids weight of the reflective particulate composition. In some non-limiting embodiments, when a minor pigment component is used, the composition comprises an amount of cristobalite selected from the range of 5 wt% to 20 wt%, or 10 wt% to 20 wt%, based on the total solids weight of the reflective particulate composition.

[0049] As described above, the reflective particulate composition may also include, 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 100% total oxide content), 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 100% total oxide content), 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 100% total oxide content), 6TILE kaolin available from Kentucky-Tennessee Clay Company (Roswell, GA) (e.g., having an Fe content of about 0.4 wt%, where the reported Fe content is adjusted to exclude LOI and normalized to 100% total oxide content), optiKasT kaolin available from Kentucky-Tennessee Clay Company (Roswell, GA) (e.g., having an Fe content of about 0.58 wt%, where the reported Fe content is adjusted to exclude LOI and normalized to 100% total oxide content), and Ione Airfloated Kaolin available from Ione Minerals, Inc. (Ione, CA) (e.g., having an Fe content of about 0.7 wt%, where the reported Fe content is adjusted to exclude LOI and normalized to 100% total oxide content). The kaolin clay may include calcined kaolin clay.

[0050] When used in a reflective granular composition, kaolin clay and other minor pigments can act as additional highly solar reflective components in addition to cristobalite. Kaolin clay can be highly reflective at some wavelengths of solar radiation reaching the Earth's surface. Kaolin clay can be reflective at the same or different wavelengths of solar radiation compared to kaolin clay. Kaolin clay can be particularly effective in reflecting some ultraviolet (UV) wavelengths of solar radiation. When the reflective granular composition is disposed on the surface of an object placed under outdoor conditions, kaolin clay can reflect at least a portion of the solar radiation incident on the object to reduce the temperature increase of the object caused by the incident solar radiation (by the object absorbing less and reflecting more solar radiation compared to the same object coated with the same composition without kaolin clay).

[0051] In some non-limiting embodiments, when used, the reflective granular composition can comprise at least 50 wt% or at least 55 wt% of kaolin clay, based on the total solids weight of the reflective granular composition. When used, the reflective granular composition can also comprise at most 70 wt% or at most 60 wt% of kaolin clay, based on the total solids weight of the reflective granular composition. In some non-limiting embodiments, when kaolin clay is used, the composition comprises an amount of kaolin clay selected from the range of 50 wt% to 70 wt% or 60 wt% to 70 wt%, based on the total solids weight of the reflective granular composition.

[0052] It should be understood that the reflective particle composition can comprise one or any combination of the foregoing minor pigment components as well as cristobalite. In some non-limiting embodiments, the reflective pigment material consists only of cristobalite. That is, in some non-limiting embodiments, 100 wt% of the reflective pigment material consists only of cristobalite and is completely free of the foregoing minor pigment components.

[0053] The reflective particle composition can comprise an effective amount of cristobalite and optionally one or more minor pigment components so as to exhibit an overall volume solar reflectance of at least 70% (also referred to herein as "total solar reflectance" (TSR) or simply "solar reflectance"), such as at least 80% or at least 85%, as measured by using a reflectometer from Surface Optics Corporation (San Diego, CA). The reflective granular composition can 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, CA) can be used, which measures the reflectance in 7 wavelength bands and uses an algorithm to calculate the TSR.

[0054] The reflective granular composition may comprise an effective amount of cristobalite and, optionally, one or more minor pigment components, so as to exhibit at least 20% UV reflectance (e.g., in the wavelength band of 335 - 380 nm), such as 20% to 80%. In some non-limiting embodiments, the reflective granular composition may exhibit at least 25% UV reflectance, such as 25% to 75%, 25% to 70%, or 40% to 70%, as measured by using a solar reflectometer from Surface Optics Corporation (San Diego, CA). For example, in some non-limiting embodiments, the reflective particulate composition may exhibit at least 50% UV reflectance, such as 50% to 70%, as measured by using a solar reflectometer from Surface Optics Corporation (San Diego, CA).

[0055] The reflective granular composition may comprise an effective amount of cristobalite and, optionally, one or more minor pigment components, so as to exhibit at least 60% visible light ("VIS") reflectance (e.g., in the wavelength band of 400 - 720 nm), such as 60% to 97% or 60% to 95%, as measured by using a solar reflectometer from Surface Optics Corporation (San Diego, CA). For example, in some non-limiting embodiments, the reflective particulate composition may exhibit at least 70% VIS reflectance, such as 70% to 98% or 70% to 97%, as measured by using a solar reflectometer from Surface Optics Corporation (San Diego, CA).

[0056] The reflective granular composition may comprise an effective amount of cristobalite and, optionally, one or more minor pigment components, so as to exhibit at least 60% infrared light ("IR") reflectance (e.g., in the wavelength band of 700 - 2500 nm), such as 60% to 98% or 60% to 97%, as measured by using a solar reflectometer from Surface Optics Corporation (San Diego, CA). For example, in some non-limiting embodiments, the particulate composition may exhibit at least 70% IR reflectance, such as 70% to 98% or 70% to 97%, as measured by using a solar reflectometer from Surface Optics Corporation (San Diego, CA).

[0057] As noted, the reflective granular composition also includes a hardening agent. As used herein, the term "hardening agent" refers to an additive that improves the strength of the resulting reflective granular composition. The materials forming the hardening agent may also provide other benefits, such as helping to act as a binder. The term "binder" refers to a constituent material that helps hold all of the constituent components together.

[0058] Non-limiting examples of hardening agents that can be used to form the reflective granular composition include sodium salts, such as sodium silicate, sodium hydroxide, or combinations thereof. Additionally, non-limiting examples of suitable sodium silicates include potassium silicate, sodium potassium silicate, other metasilicates known in the art, or combinations thereof. Additional non-limiting examples of hardening agents include sodium carbonate, sodium chloride, sodium polyacrylate, sodium sulfate, sodium thiosulfate, sodium phosphate, or mixtures thereof.

[0059] In some non-limiting embodiments, the hardening agent (such as 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 (such as sodium silicate) may also comprise at most 40 wt%, or at most 30 wt%, or at most 25 wt%, or at most 20 wt% of the composition, based on the total solids weight of the composition. In some non-limiting embodiments, the composition comprises an amount of hardening agent in the range of 5 wt% to 40 wt%, 5 wt% to 30 wt%, or 5 wt% to 15 wt%, based on the total solids weight of the composition.

[0060] Furthermore, in order to improve the consistency and adhesion of the particles within the slurry, a material acting as a pure binder material can be added. Suitable binder materials include water-soluble polymers, such as water-soluble synthetic polymers. The 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 comprise polyvinyl alcohol.

[0061] In some non-limiting embodiments, a method of preparing a reflective granular composition includes: mixing cristobalite with water to form a slurry; adding a hardening agent to the slurry and mixing; granulating and / or drying the slurry; calcining the resulting material to form a sintered material comprising cristobalite and the hardening agent; and crushing and screening the sintered material to form a reflective granular composition having a desired particle size. It should be understood that the granulated and / or dried slurry is calcined such that the quartz sand is converted to cristobalite. It should be understood that the quartz sand may include coarse sand, fine sand, all sand, abrasive sand, or any combination thereof.

[0062] As described above, quartz sand is mixed with water and a hardening agent to form a slurry. The slurry can form a substantially homogeneous mixture. As used herein, the term "substantially" is used as an approximation term rather than a degree term and is intended to account for the inherent deviations and variations in the properties or values being measured, observed, or calculated. Thus, the term "substantially homogeneous" means that while the mixture may not be perfectly homogeneous, the mixture will be considered homogeneous to one of ordinary skill in the art.

[0063] In some non-limiting embodiments, the method of forming the slurry can include adding a liquid medium (such as water) to the mixture of components 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 composition is desired to be ultimately moldable or flowable. However, in some non-limiting embodiments, the liquid medium can be added to the particulate mixture in an amount of 20 - 50 wt%, such as 30 - 40 wt%, based on the total weight of the slurry mass. For example, in some non-limiting embodiments where the composition is desired to be moldable, the liquid medium can be added to the particulate mixture in an amount of 20 - 40 wt%, such as 25 - 35 wt% or 25 - 30 wt%, based on the total weight of the slurry mass. In some non-limiting embodiments where the composition is desired to be flowable, the liquid medium can be added to the particulate mixture in an amount of 30 - 50 wt%, such as 35 - 45 wt% or 35 - 40 wt%, based on the total weight of the slurry mass.

[0064] The slurry can then be processed into a granular form. 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. Drying can be carried out at any suitable temperature to substantially remove the liquid medium. As described above, the term "substantially" as used herein is an approximation term rather than a degree term, and the phrase "substantially remove the liquid medium" is intended to account for the inherent deviations in the measurement, calculation, or observation of the amount of liquid medium remaining in the mixture after drying. For example, if the amount of liquid medium remaining in the mixture is either undetectable or otherwise negligible, the liquid medium is considered to be substantially removed, as would be understood by one of ordinary skill in the art.

[0065] The temperature of the dried 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 process. 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). Additionally, the time required to dry the wet mixture is not particularly limited and can vary depending on the consistency of the wet mixture, the liquid medium used in the wet mixture, the temperature at which drying is carried out, 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).

[0066] The dried mixture can then be crushed and / or calcined (or subjected to a heat treatment). In embodiments where the dried mixture is both crushed and calcined, the dried mixture can be first crushed and then calcined, or first calcined and then crushed. In some non-limiting embodiments, using a sieve and crusher of the desired size, the dried mixture can be first crushed (before calcination) to the desired particle size. This pre-crushing can allow any fine material (or fine particles) to be reintroduced into the product feed, thereby reducing the amount of waste generated by the process. The fine particles generated during the crushing process can be recycled by reintroducing them into the production feed. However, due to their smaller particle size, it may be necessary to increase the amount of liquid medium required to achieve the desired consistency of the wet mixture. In some non-limiting embodiments, the recycled fine particles can be added to the production feed in an amount of 25 wt% or less of the feed.

[0067] As described above, according to some non-limiting embodiments, the dried mixture can be calcined before or after crushing. The calcination process can be carried out at any suitable temperature and for any suitable length of time. For example, in some non-limiting embodiments, the dried mixture (before or after crushing) can be calcined (or fired) 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). Additionally, in some non-limiting embodiments, the dried mixture can be calcined (or fired) for 30 minutes to 90 minutes (such as 45 minutes to 75 minutes, 50 minutes to 70 minutes or 60 minutes). As previously mentioned, the calcination process is carried out to bind the quartz sand particles together and convert the quartz sand to cristobalite.

[0068] In some non-limiting embodiments, the resulting particles can have 40 lb / ft 3 to 75 lb / ft 3 (such as 50 lb / ft 3Up to 75 lb / ft 3 、40 lb / ft 3 Up to 60 lb / ft 3 、50 lb / ft 3 Up to 60 lb / ft 3 or 45 lb / ft 3 Up to 60 lb / ft 3 ) bulk density. In some non - limiting embodiments, the resulting particulate composition can have a bulk density of 50 lb / ft 3 Up to 60 lb / ft 3 (e.g., 52 lb / ft 3 Up to 58 lb / ft 3 or 53 lb / ft 3 Up to 56 lb / ft 3 ). The relatively low bulk density of the particulate composition enables significant cost savings. For example, the lower bulk density allows for less particulate (or particles) to be applied per unit area (or square), while still achieving solar reflectance benefits (e.g., high total solar reflectance and / or UV, VIS, and / or IR reflectance).

[0069] Compounds such as transparent treatments or transparent coating compounds can be applied to the reflective particulate composition to coat or treat the surface of the particles. Such compounds include, but are not limited to, at least one of the following: silanes, siloxanes, polysiloxanes, organosiloxanes, silicates, organosilicates, silicone resins, acrylates, urethanes, polyurethanes, glycol ethers, and mineral oils. Exemplary coatings, surface treatments, and methods of coating and treating particles are shown and described in US 7,241,500, US 3,479,201, US 3,255,031, US 3,208,571, and US 2020 / 0308413, which are hereby incorporated by reference in their entirety. The coating applied to the particles can provide enhanced protection of the particles from asphalt contamination.

[0070] To maintain the high solar reflectance of the particles, the compound should be applied such that the coating and / or surface treatment does not significantly reduce the reflectance of the particles. For example, many suitable coatings and / or surface treatments can be sealants or other transparent coatings that do not adversely affect the overall solar reflectance of the particles. In some non - limiting embodiments, the particles can be treated with an emulsion of silanes and siloxanes without adding solvents. In another embodiment, the particles can be treated with SILRES BS3003 available from Wacker Chemi AG (Munich, Germany).

[0071] A variety of methods and processes known to those skilled in the art can be used to apply surface treatments and / or coatings to the particles. For example, in one exemplary embodiment, after the raw materials are crushed, sized, and packaged according to the preferred screen size, the particles can be saturated with the treatment by adding the particles to an aqueous solution and then immediately drying the particles at a temperature not exceeding 600°F (316°C) to drive off the excess moisture. In another exemplary embodiment, after the raw materials are crushed, sized, and packaged according to the preferred screen size, the particles can be post-treated by spraying an aqueous solution onto the particles and then immediately drying the particles at a temperature not exceeding 600°F (316°C) to drive off the excess moisture. In yet another exemplary embodiment, after the raw materials are crushed and sized according to the preferred screen size, the particles can be treated by spraying an aqueous solution onto the particles and then immediately calcining the dried particles at a temperature not exceeding 600°F (316°C) to drive off the excess moisture and then packaging the particles. In still another embodiment of coating and / or treating the particle surface, after the raw materials are crushed and sized according to the preferred screen size, the particles are treated by spraying an aqueous solution onto the particles and then immediately ventilating the particles to drive off the excess moisture and then packaging the particles. The coating and / or surface treatment can be applied as-is (e.g., off-the-shelf) or from an aqueous dilution. The dilution ratio can be from 1:5 to 1:200. The dilution can be prepared from deionized water.

[0072] In some non-limiting embodiments, the reflective particles are crushed and sized to have a particle size selected from the range of 8 mesh to 40 mesh.

[0073] In some non-limiting embodiments, a method of preparing a reflective granular composition includes: mixing cristobalite and a hardener (as described above) together to form a reflective granular composition. The method can also include crushing and sizing 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.

[0074] The reflective granular composition (e.g., untreated or treated) can be used to form building materials. The building materials can include roofing materials or other building materials. The building materials can be located in an outdoor environment.

[0075] Roofing materials can be formed by applying the reflective granular composition to an asphalt layer. The asphalt layer can include asphalt or modified asphalt, which is modified with at least one reinforcing material (e.g., polyester or fiberglass). Such roofing materials with the reflective granular composition applied to the asphalt layer can constitute a cool roof system.

[0076] Examples

[0077] The following examples are presented to demonstrate 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 indicated.

[0078] Example 1

[0079] Preparation of Reflective Granular Composition

[0080] A reflective granular composition was prepared by first mixing 600 g of dry quartz sand (available from U.S. Silica, 10, D 90 with a particle size of 10 μm) with water. Next, 60 g of a 50% strength sodium silicate solution ( available from PQ Corporation) was added to the mixture, and the final sand concentration was adjusted to 50% by adding water to form a final slurry. The slurry was dried overnight at 100 °C and then the dried mass was calcined in a furnace at 1150 °C for 2 hours to be sintered and then cooled to ambient temperature. The sintered material was crushed and screened through a jaw crusher to form particles such that the particle size was between 8 mesh and 40 mesh.

[0081] The TSR of the particles was measured using a Devices and Services Solar Spectrum Reflectometer Model SSR. The resulting TSR of the particles was 95.133.

[0082] Examples 2 - 6

[0083] Preparation of Reflective Granular Composition

[0084] Reflective granular compositions were prepared using the same materials and procedures as in Example 1, but with different amounts of sodium silicate, as shown in Table 1. Each of the reflective granular compositions of Examples 2 - 6 exhibited excellent TSR.

[0085] Table 1

[0086]

[0087] Example 7

[0088] Preparation of Reflective Granular Composition

[0089] A reflective granular composition was prepared by first mixing 600 g of dry quartz sand ( 5, available from U.S. Silica, D 90 with a particle size of 5 μm) with water. Next, 360 g of a 50% strength sodium silicate solution ( Commercially available from PQ Corporation) was added to the mixture, and the final concentration of sand was adjusted to 50% by adding water to form a final slurry. The slurry was dried overnight at 100 °C and then the dried mass was calcined in a furnace at 1150 °C for 2 hours to be sintered and then cooled to ambient temperature. The sintered material was crushed and screened through a jaw crusher to form particles such that the particle size was between 8 mesh and 40 mesh.

[0090] The TSR of the particles was measured using a Devices and Services Solar Spectrum Reflectometer Model SSR. The resulting TSR of the particles was 91.17.

[0091] Those skilled in the art will readily understand that the present invention can be modified without departing from the concept disclosed in the foregoing specification. Accordingly, the specific embodiments described in detail herein are illustrative only and do not limit the scope of the present invention, which scope should be given the full breadth of the appended claims and any and all equivalents thereof.

Claims

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.

2. The reflective granular composition according to claim 1, wherein the hardener comprises a sodium salt.

3. The reflective granular composition according to claim 1, wherein the reflective pigment material consists of cristobalite.

4. The reflective granular composition according to claim 3, wherein the composition comprises at least 50 wt% of cristobalite, based on the total solids weight of the composition.

5. The reflective granular composition according to claim 4, wherein the composition comprises an amount of cristobalite in the range of 50 wt% to 95 wt%, based on the total solids weight of the composition.

6. The reflective granular composition according to claim 1, wherein the composition comprises an amount of hardener in the range of 5 wt% to 40 wt%, based on the total solids weight of the composition.

7. The reflective granular composition according to claim 1, wherein the cristobalite has a d selected from the range of 1 μm to 40 μm 90 .

8. The reflective granular composition according to claim 1, wherein the reflective particles have a particle size selected from the range of 8 mesh to 40 mesh.

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

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

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

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

13. A method for preparing a reflective granular composition, comprising: mixing quartz sand with water to form a slurry; adding a hardener to the slurry and mixing; granulating and / or drying the slurry; calcining the resulting material to form a sintered material comprising cristobalite and the hardener; and crushing and screening the sintered material to form a reflective granular composition having a desired particle size.

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

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

16. The method according to claim 13, wherein the hardener comprises a sodium salt.

17. The method according to claim 13, wherein the reflective pigment material of the reflective granular composition consists of cristobalite.

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

19. A method for preparing a reflective granular composition, comprising: Fused quartz and a hardening agent are mixed together to form a reflective granular composition.

20. The method according to claim 19, further comprising crushing and screening the reflective particulate composition to have a desired particle size.

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

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