Silica particle composition for thermal insulation

Abstract

A composition comprising a mixture of a) silica aerogel particles having particle sizes in a range from 0.1 mm to 5 mm and b) hydrophobic silica-containing aciniform particles having a methanol number of 30 to 70 and carbon content up to 6 wt%, wherein the silica aerogel particles and hydrophobic silica containing particles are present in a ratio from 0:100 to 80:20; and wherein the heat control member has a thermal conductivity at 25 °C of approximately 5-40 mW / m.K and a thickness of 0.1-10 mm.

Description

TITLE OF THE INVENTIONSilica Particle Composition for Thermal InsulationBACKGROUND OF THE INVENTION1. Field of the Invention.

[0001] This invention relates to an silica-containing particle composition (i.e., a composition comprising silica-containing particles) for thermal insulation, in particular, for multi-cell rechargeable batteries.2. Description of the Related Art.

[0002] Aerogel particles can have a very low density, high porosity, and small pore diameters. Aerogels, and in particular silica aerogels, exhibit low density and low thermal conductivity, making them useful as insulative materials. Aerogels can be formed by removing solvent from hydrogels, such as through supercritical drying techniques or via solvent substitution combined with ambient pressure drying. Silica aerogels are typically hydrophilic but can be rendered hydrophobic through the use of specific treating agents.

[0003] In the broadest sense, i.e., when regarded as “gels with air as the dispersant,” aerogels are manufactured by drying a suitable gel. When used in this sense, the term “aerogel” includes aerogels in the narrower sense, such as xerogels and cryogels. A gel is designated as an aerogel in the narrower sense if the liquid is removed from the gel at temperatures above the critical temperature and starting from pressures that are above the critical pressure. In contrast to this, if the liquid is removed from the gel sub-critically, for example with the formation of a liquidvapor boundary phase, then the resulting gel is, in many instances, referred to as xerogel. It should be noted that the gels according to the present invention are aerogels in the sense that they are gels with air as the dispersing media.

[0004] Due to their excellent insulating properties, aerogels have been incorporated in various types of articles, including heat control articles (sheets, pads or blankets, for example) designed for applications such as construction, refrigeration, pipe transport and others. One application of increased interest relates to the insulation of rechargeable batteries in electrical vehicles (EV).

[0005] US9399864 discloses a wet laid aerogel blanket produced from a slurry of aerogel particles with a polymer binder. CN112430018 discloses a fiber paper that is impregnated with aerogel that is retained by a silica binder. CN112522949 discloses an aerogel mat in which an aerogel slurry is injected into a glass fiber mat which is then immersed in a slurry containing a polymer curing agent. CN112681009 discloses a two layer paper system that is impregnated with an organic solution of silica aerogel. Still, there is a need for a thin aerogel blanket that maintains thermal conductivity and tensile strength and has reduced amounts of aerogel while maintaining thermal insulation performance.SUMMARY OF THE INVENTION

[0006] In one embodiment, a composition comprises a mixture of a) silica aerogel particles having particle sizes in a range from 0.1 mm to 5 mm and b) hydrophobic silica-containing aciniform particles having a carbon content up to 6 wt% and a methanol number of 30 to 70, preferably 45 to 70, wherein the silica aerogel particles and hydrophobic silica containing particles are present in a ratio from 0:100 to 80:20; and wherein the composition has a thermal conductivity at 25 °C of approximately 5-40 mW / m.K and a thickness of 0.1-10 mm.

[0007] The hydrophobic silica-containing aciniform particles may be selected from the group consisting of fumed silica, silicon-treated carbon black, silica-coated carbon black, fumed mixed metal oxides, and silica-carbon black composite particles. For example, the hydrophobic silica- containing particles may be hydrophobic fumed silica. The hydrophobic silica-containing particles may be hydrophobized by a hydrophobizing silane or a silazane. The hydrophobic silica-containing particles may be fumed silica particles having a surface area from 60 to 340 m2 / g, preferably from 60 to 250 m2 / g, surface treated with a silica-treating agent.

[0008] The hydrophobizing silane may be R.4-nSiXnwherein n is 1-3, each R is independently selected from the group consisting of hydrogen, a C1-C30 branched or straight chain alkyl or alkenyl group, a C3-C18 haloalkyl group, C3-C10 cycloalkyl, and a C6-C14 aromatic group, preferably a C1-C4 branched or straight chain alkyl or alkenyl group, and each X is independently a Cl -Cl 8 branched or straight chain alkoxy group or halo, with no more than three groups R being hydrogen.

[0009] The mixture may further include fibers, e.g., glass fibers, ceramic fibers, synthetic polymer fibers, carbon fiber, natural polymer fibers, mineral wool, or a mixture of two or more of these. The fibers may be blackened or coated with a metal.

[0010] At least a portion of the silica aerogel present in the heat control member may incorporate an opacifier and / or be coated with or impregnated with a heat absorbing material.

[0011] The mixture may further include one or more components selected from the group consisting of fiber, opacifier, fire retardant, heat absorbing material, phase change material, binder, defoamer, dispersant, emulsifier, surfactant, and flocculant.

[0012] The composition may further include a sheet or mat comprising silicone, polyvinylidene fluoride, chlorinated polyethylene, aramid fibers, or aramid aerogel.

[0013] The composition may further include an envelope encapsulating the mixture.

[0014] A heat control member may comprise the composition and may be in the form of a blanket or pressed pad.

[0015] The heat control member may meet the specifications of UL94 V0.

[0016] The composition can further include materials such as IR opacifiers, flame or fire retardants, phase change materials, heat absorbers, processing aids, and so forth. Binders, water, dispersants, emulsifiers, flocculating agents, etc. can be included as needed in the manufacture of the heat control article.

[0017] The above and other features of the invention including various details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0019] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Also, all conjunctions used are to be understood in the most inclusive sense possible. Thus, the word "or" should be understood as having the definition of a logical "or" rather than that of a logical "exclusive or" unless the context clearly necessitates otherwise. Further, the singular forms and the articles "a", "an" and "the" are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms: includes, comprises, including and / or comprising, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Further, it will be understood that when an element, including component or subsystem, is referred to and / or shown as being connected or coupled to another element, it can be directly connected or coupled to the other element or intervening elements may be present.

[0020] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. All proportions and percentages are on a weight basis unless otherwise indicated.

[0021] In one embodiment, a composition or a heat control member comprises a mixture of a) silica aerogel particles having particle sizes in a range from 0.1 mm to 5 mm and b) hydrophobic silica-containing aciniform particles having a methanol number of 30 to 70, preferably 45 to 70, and a carbon content up to 6 wt%, wherein the silica aerogel particles and hydrophobic silica containing particles are present in a ratio from 0:100 to 80:20; and wherein the heat control member has a thermal conductivity at 25 °C of approximately 5-40 mW / m.K and a thickness of 0.1-10 mm. Preferably, the composition is a silica-containing particle composition, meaning that the composition comprises silica-containing particles.

[0022] Any type of silica aerogel particle(s) can be used in the mixture. Aerogels may be formed as described in US7470725. Suitable aerogels can be made from waterglass or from organic materials such as TEOS and TMOS. To reduce the radiative contribution to thermal conductivity, the aerogel particles can incorporate IR opacifiers, such as carbon black, alumina, graphite, titanium dioxide, iron oxide, silicon carbide, zirconium dioxide, or mixtures thereof. Aerogel particles are available from a variety of sources, including from Cabot Corporation under the ENOVA and ENTERA brands and from JIOS Aerogel under the AEROVA brand.

[0023] The silica aerogel can have particle sizes in a range from 0.1 mm to 5 mm, for example, from 0. 1 mm to 4 mm, from 0. 1 to 0.5 mm, from 0.1 mm to 1 mm, from 0.1 mm to 1.5 mm, or from 1 mm to 4 mm. The aerogels can have narrow or wide particle size distributions and can be in the form of comminuted powders. The diameter of an aerogel particle may be measured along the longest cross sectional line in a given particle, or particle size ranges may be measured by sieving.

[0024] The silica aerogel particles can be hydrophobic, exhibiting a water contact angle of greater than 90 degrees. Examples of commercially available such aerogels are ENOVA® brand aerogels, ENTERA® brand aerogels, and IC3110, P100, P150, and P200 aerogels, all from Cabot Corporation. Aerogel particles are also commercially available as mixtures with opacifiers such as carbon black. In some embodiments, the aerogel particles have porosities greater than about 60% and densities of less than about 0.4 g / cc. In other embodiments, aerogel particles have densities of from about 0.05 to about 0.15 g / cc.

[0025] The thermal conductivity of the aerogel particles at 25 °C can be less than about 40 mW / m K, less than about 25 mW / m K, or from about 12 mW / m K to about 18 mW / m K, or lower. To reduce flammability, the aerogel particles may be low calorie aerogels, such as those having a caloric content of, for example, less than 10 MJ / kg, less than 8 MJ / kg, less than 7 MJ / kg or less than 6 MJ / kg.

[0026] As the aerogel is preferably pre-formed (prepared prior to the fabrication of the composition or heat control article), any desirable aerogel structure, morphology, or other characteristic can be chosen, and this characteristic can often persist into the final product.

[0027] The hydrophobic silica-containing aciniform particles, i.e., aggregates, similar to a bundle of grapes, of primary particles fused together, may be a hydrophobic silicon-treated carbon black, silica-coated carbon black, silica-carbon black composite particles, fumed silica,or fumed mixed metal oxides. The particle aggregates may be further connected to form agglomerates. Preferably, the hydrophobic silica-containing aciniform particle is a hydrophobic fumed silica. Alternatively or in addition, hydrophobic silicon-treated carbon black, silica- coated carbon black, silica-carbon black composite particles, or titania-containing mixed metal oxides may be used to introduce infrared absorption capability to the heat control member. The carbon content of the hydrophobic silica may be up to 6 wt%, for example, 0.5- 4.5 wt% or 0.6 to 4.2 wt%. Carbon content may be measured by combusting the silica in a pure oxygen environment and determining the concentration of the resulting carbon dioxide gas. Suitable instruments for performing this analysis include those commercially available from LECO Corporation and others known to those of skill in the art. Alternatively or in addition, the methanol number of the hydrophobic silica-containing particles may be from 30 to 70, preferably from 45-70. Methanol number may be measured using Rhesca Wet-lOlP powder wettability tester (Rhesca Co. Ltd.) according to the manufacturer’s instructions using a starting solution of 60 mb, a stir rate of 300 rpm, a methanol flow rate of 2 mL / min. The starting solution is degassed by stirring for at least 5 min at 1000 rpm prior to adding the sample. The measurement is typically run with 0.1 g of sample in a starting solution of 30% methanol. However, a more or less hydrophobic starting solution may be employed depending on the hydrophobicity of the sample. The test is run by titrating the starting solution with methanol; the methanol number is the amount of methanol in the solution when the sample, which is initially sitting on top of the starting solution, starts to wet into, or sink, into the solution, and may be calculated automatically by the instrument. Alternatively, a threshold methanol number of a powder may be determined by carefully pouring a sample onto the surface of a methanol-water solution having a known methanol concentration. If the sample does not wet into the solution, its methanol number is higher than the concentration of methanol in the solution.

[0028] The silica aerogel particles and hydrophobic silica-containing aciniform particles are present in a ratio (aerogel: aciniform particles) from 0: 100 to 80:20, for example, from 5:95 to 70:30, from 10:90 to 60:40, from 20:80 to 55:45, from 30:70 to 50:50, or from 40:60 to 75:25. The amount of silica-containing particles in the composition or the heat control member may be 10-70% by weight, for example, from 15 to 65 wt%, from 20 to 60 wt%, from 25 to 55 wt%, from 30 to 50 wt%, or from 35 to 45 wt%.

[0029] In some embodiments, silica-containing aciniform particles for use in the heat control members described herein, prior to any surface hydrophobizing treatment, have a BET surface area from 60 to 340 m2 / g, preferably from 60 to 250, more preferably, from 60 to 150 m2 / g. As surface area increases, the effect of the hydrophobic aciniform silica on the tensile strength of a heat control member in the form of a blanket, e.g., a wet laid blanket, transitions from positive to negative.

[0030] Preferably, the hydrophobic silica-containing aciniform particles may be hydrophobic fumed, or pyrogenic, silica. Fumed silica typically has a primary particle size from 2-20 nm and is formed from the vapor phase. In one manufacturing process, silica (usually sand) is vaporized at about 2000°C and cooled to form anhydrous amorphous silica particles. Alternatively, silica can be sublimed at about 1500°C in the presence of a reducing agent (e g., coke) to form SiO, which can be oxidized to form particulate silica. Other methods of producing fumed silica include, for example, oxidation of SiCh at high temperatures or burning SiC in the presence of methane or hydrogen.

[0031] A well-documented process for producing fumed metal oxides involves the hydrolysis of suitable feed stock vapor (such as aluminum chloride for a fumed alumina, or silicon tetrachloride for fumed silica) in a flame of hydrogen and oxygen. Molten particles of roughly spherical shape are formed in the combustion process, and the particle diameters may be varied through control of process parameters. These molten spheres, referred to as primary particles, fuse with one another by undergoing collisions at their contact points to form branched, three- dimensional chain-like aggregates. The formation of the aggregates is considered to be irreversible as a result of the fusion between the primary particles. During cooling and collecting, the aggregates undergo further collisions that may result in some mechanical entanglements to form agglomerates. These agglomerates are thought to be loosely held together by van der Waals forces and can be reversed, i.e., de-agglomerated, by proper dispersion in a suitable media or by milling, e.g., in a jet mill or hammer mill.

[0032] Alternative methods for producing pyrogenic silica particles have been developed, as described, for example, in US Patents Nos. 4,755,368, 6551567, and 6,702,994, US Patent Publication No. 20110244387, in Mueller, et al., “Nanoparticle synthesis at high production rates by flame spray pyrolysis, ” Chemical Engineering Science, 58: 1969 (2003), in Naito, et al., “New Submicron Silica Produced by the Fumed Process, ” published in NIP 28: InternationalConference on Digital Printing Technologies and Digital Fabrication 2012, 2012, p. 179-182, and in Kodas and Hampden- Smith, Aerosol Processing of Materials, Wiley-VCH, 1998, the contents of all of which are incorporated by reference. Other methods for preparing pyrogenic silica particles are known.

[0033] Both hydrophilic fumed silicas that may be surface treated for use in the embodiments provided herein and hydrophobic fumed silicas are available commercially. Non-limiting examples of fumed silicas include CAB-O-SIL fumed silica available from Cabot Corporation, HDK fumed silica products available from Wacker Chemie AG, and AEROSIL fumed silica available from Evonik Industries, Essen, Germany.

[0034] Alternatively or in addition, silica-containing aciniform particles that also contain other materials may also be used. For example, silica-coated carbon black may be employed. Exemplary silica-coated carbon blacks include those described in US6541113, US6197274, and US9598560, the contents of all of which are incorporated herein by reference. Silicon-treated carbon black having a silica phase and a carbon phase may also be employed. Methods of making and surface treating various types of silicon-treated carbon blacks are described in U.S. Patent Nos. 7,199,176; 6,709,506; 6,686,409; 6,534,569; 6,469,089; 6,448,309; 6,364,944; 6,323,273; 6,211,279; 6,169,129; 6,057,387; 6,028, 137; 6,008,272; 5,977,213; 5,948,835; 5,919,841; 5,904,762; 5,877,238; 5,869,550; 5,863,323; 5,830,930; 5,749,950; 5,747,562; 5,622,557; and 6,929,783; and U.S. Published Patent Application No. 2002 / 0027110, all incorporated in this application, in their entirety by reference herein. Carbon black-silica composite particles such as those discussed in US10800925, the entire contents of which are incorporated herein by reference, may also be employed. Co-fumed silica particles such as silica-titania or silica-alumina mixed oxides may also be used. Exemplary hydrophilic and hydrophobic mixed oxides are disclosed in US5424258, US6197469, US7083769, US20100016490, US20050239921, US6328944, US4297143, and US7897256, the entire contents of all of which are incorporated herein by reference. Any of these silica-containing materials that are not already hydrophobic may be surface treated in the same manner as fumed or precipitated silica as described below.

[0035] In certain embodiments, the hydrophobic silica-containing aciniform particle may be produced by treating hydrophilic particulate silica, e g., fumed silica, with a surface treating agent known to one of skill in the art. Silica treating agents can be any suitable silica treatingagent and can be covalently bonded to the surface of the silica particles or can be present as a non-covalently bonded coating. Typically, the silica treating agent is bonded either covalently or non-covalently to silica. In many cases, the silica treating agent can be a hydrophobizing silane or silazane or other silica treating agents, e.g., as known in the art.

[0036] In certain embodiments, the silica-treating agent comprises a hydrophobizing silane. For example, the silica-treating agent can be a compound of the formula: R 4-nSiXn, where n is 1-3, each R is independently selected from the group consisting of hydrogen, a C1-C30 branched or straight chain alkyl or alkenyl group, a C3-C18 haloalkyl group, C3-C10 cycloalkyl, and a C6- C14 aromatic group, preferably a C1-C4 branched or straight chain alkyl or alkenyl group, and each X is independently a Cl -Cl 8 branched or straight chain alkoxy group or halo, with no more than three groups R being hydrogen. In certain embodiments, the silica-treating agent comprises a hydrophobizing silazane, for example, the silica-treating agent can be hexamethyldisilazane or octamethyltrisilazane. Preferred hydrophobic treating agents for silicas for use as the hydrophobic silica-containing aciniform particles in various embodiments herein include hexamethyldisilazane, alkyltrialkoxysilanes and alkyldialkoxysilanes such as hexamethyldisiloxane, and dimethyldichlorosilane.

[0037] Hydrophilic silica-containing aciniform particles may be surface treated using any suitable method known to those of skill in the art. Dry silica particles may be surface treated using wet or dry techniques known to those of skill in the art. For example, a dry treatment method may include stirring or mixing the metal oxide and the hydrophobizing agent in a fluidized bed reactor. Alternatively, a wet treatment method may include dispersing the metal oxide into a solvent to form a metal oxide slurry, and adding the hydrophobizing agent to the slurry to thereby modify the metal oxide surface with the hydrophobizing agent. In a preferred embodiment, the mixture is then held for a period of time at a temperature sufficient to modify the surface properties of the metal oxide.

[0038] In addition to the aerogel and hydrophobic silica-containing aciniform particles, the composition and / or heat control article described herein further includes one or more other ingredients. In many cases, these ingredients or components are selected to bring about specific functions and / or properties to the final articles (e.g., a blanket). In some cases, the types and / or amounts of added ingredients are selected to achieves a balance or compromise between desirable versus less desirable contributions the ingredient might make to the final product.Manufacturing parameters, final applications or other factors can be considered in selecting types and / or amounts of ingredients to be employed.

[0039] Among the ingredients that, when added to silica-containing aciniform particles, can affect properties of the finished article are fibrous materials. Fibrous materials may be present in an amount of 5 - 70 wt%, for example, 10-55 wt%, 15-45 wt%, 20 to 35 wt%, or 10 to 30 wt% with respect to the total weight of the silica-containing particle composition or heat control article. Specific implementations utilize a fibrous component that includes inorganic fibers and / or a polymeric fiber that is temperature resistant. Exemplary inorganic fibers include include ceramic wool, ceramic fibers, and glass fibers. Examples of polymeric fibers include polybenzimidazole (PBI), an aromatic polyamide (aramid) or any combination thereof.

[0040] Whereas ceramic fibers are typically made by a drawing process, then chopped to a desired length, a ceramic “wool” (or other types of wool, such as mineral wool, also sometimes referred to as “stone” wool) is often made by spinning a melt. Generally, wools tend to have longer, more entangle-prone fibers. Individually, a wool fiber may not be any stronger than a shorter ceramic fiber (made by drawing and chopping). In bulk, however, wools may have an additive effect that can improve the mechanical integrity of the composition and / or the heat control article.

[0041] In many cases, the diameter of a wool fiber is within a range of from about 1 micron (pm) to several hundreds of microns. Fiber length can be within a range of from about 100 pm to several hundreds of pm or longer, sometimes several hundreds of millimeters (mm) long.

[0042] These high aspect ratio wools also have the effect of improving drainage and retention in a wet laid article, as they provide extra surface area for well-dispersed active materials to aggregate during coagulation processes. This reduces the amount of active material that is removed with the excess process water during forming processes.

[0043] Amounts of ceramic wool that can be employed often will depend on desired properties (e g., tensile strength, tear resistance, impact resistance), intended use and / or other factors. Ceramic wools can be provided in an amount within a range of 0.5 to 100 wt % (relative to the weight of the fibrous component utilized to prepare the composition). In illustrative examples, it is present in an amount within a range of from about 5 to about 30 wt%. For instance, it can be present in the fibrous component in an amount of from about 10 to about 20 wt %.

[0044] Relative to the finished article, e.g., a blanket, ceramic wools can be present in the end product in an amount within a range of 0.25% to 4wt% of the weight of the article, e.g., from about 0.5 to about 2 wt %, such as, for instance, within a range of from about 0.5 to about 1.0; from about 0.5 to about 1.5; from about 0.5 to about 2.0 wt %; or within a range of from about 1.0 to about 1.5; from about 1.0 to about 2 wt %; or from about 1.5 to about 2.0 wt%.

[0045] Suitable ceramic wools include aluminum (provided as AI2O3), silicon (in the form of SiCh) and iron (in Fe2Ch) or combinations of any of these. Some ceramic wools can also include titania (TiCh) in addition to or in place of any of these components.

[0046] While not a required element, the presence of zirconium can bring about mechanical benefits and / or can contribute to the temperature resistance of the final silica-containing particle composition and / or heat control article (e.g., a blanket). In some implementations, zirconium (typically in the form of zirconium oxide (ZrCh) is provided in a zirconium containing wool that can also include other elements such as aluminum, silicon, iron and / or titanium. Commercially, Ceramaterials (Dingmans Ferry, PA) provides two types of spun fibers, one with a higher zirconia concentration (with temperature resistance up to 2600°F / 1400°C) and one with lower zirconia loading (2300°F / 1400°C).

[0047] In a finished product, a blanket, for instance, ceramic wools can be identified by analytical techniques such as high resolution microscopy of a uniform cross section of the sample product, e.g., a blanket. It is believed that, even after processing operations, ceramic wools would retain a differentiated conformation compared to a chopped ceramic fibers. Other techniques that may be applicable include Scanning Electron Microscopy (SEM) using Energy Dispersive X-ray (EDX) capability (often abbreviated as “SEM / EDX”), correlating elements typical in concentration to ceramic wools as differentiated from other types of fibers.

[0048] Another type of wool that can be employed to prepare the composition described herein is mineral wool (also known in some instances as “stone” wool). Mineral wool is commercially available from Rockwool A / S under the trade name of “Rockwool®” mineral wool, from Knauf Insulation (Shelbyville, IN, USA), and from other suppliers. Amounts of mineral wool can be the same or similar to those used in the case of ceramic wools. Other ranges can be employed, however.

[0049] Mineral wool can be identified in a finished article, e.g., a blanket, by techniques such as Scanning Electron Microscopy (SEM) using Energy Dispersive X-ray (EDX) capability(Often abbreviated as “SEM / EDX”), correlating elements typical in concentration to mineral wools as differentiated from other types of fibers.

[0050] In some embodiments, the composition described herein contains temperature resistant polymeric materials in various forms. Some approaches utilize aramid fibers that can be defined as “pulp” (between 0.1-6 mm) or short cut fibers (>6 mm). Aramid short cut fibers and pulp are widely available, with the major worldwide manufacturer being Dupont (under the Kevlar® tradename). Alternatively or in addition, longer aramid fibers, cut to lengths such as 3 mm, 6 mm, or 12 mm, may also be employed.

[0051] Other approaches utilize polybenzimidazole (PBI) fibers, typically characterized by excellent heat and chemical resistance. As PBI fibers have no discernible melting point, they do not ignite or drip when exposed to high temperatures. PBI fibers can be purchased from PBI Performance Products (Charlotte, NC). PBI fibers may be at least .1 mm long, e.g., from 0.5 to 10 mm, from 1-8 mm, or from 2-6 mm.

[0052] Materials such as aramid or PBI fibers are believed to be particularly useful in addressing the swelling and contraction observed with battery packages charging or discharging under hot or cold conditions. Allowing the battery encasement to expand alleviates pressure on the battery compartment, reducing wear and tear on battery materials.

[0053] While still imparting these advantageous properties, these polymeric fibers are typically used in amounts that are as low as possible, as their addition can compromise a desired low flammability rating of the finished article, e.g., blanket.

[0054] PBI and / or aramid fibers can be provided in amounts within a range of from about 0.5 to 100 wt % (relative to the weight of the fibrous component utilized to prepare the composition). In illustrative examples, they are present in an amount within a range of from about 5 to about 30 wt% or from 25% to 80%. For instance, they can be present in the fibrous component in an amount of from about 10 to about 20 wt %.

[0055] In many cases, fibers such as aramid or PBI are used in amounts of 0.25% to 4% (based on the weight of the silica-containing particle composition or heat control article), e.g., from about 0.5 to about 2 wt %, such as, for instance, within a range of from about 0.5 to about 1.0 wt %; from about 0.5 to about 1.5 wt%; from about 0.5 to about 2.0 wt %; or within a range of from about 1.0 to about 1.5 wt %; from about 1.0 to about 2 wt %; or from about 1.5 to about 2.0 wt%.

[0056] In a finished product, e.g., a blanket, aramid or PBI fibers can be identified by techniques such as SEM / EDX, differentiating the polymeric structures from the surrounding inorganic environment.

[0057] Ceramic fibers are known for their good corrosion resistance as well as good oxidation resistance at high temperatures. Generally, ceramic fibers are characterized by a polycrystalline (rather than amorphous) structure. Some, e.g., refractory ceramic fibers, are particularly useful as thermal insulating materials for high temperature applications. In some embodiments, the ceramic fibers represent the major ingredient (more than 50 % by weight relative to the total weight of the fibrous component).

[0058] Suitable chopped ceramic fibers that can be employed in the composition described herein include one or several (two, three, four or more) inorganic oxides, such as AI2O3, B2O3, Na2O, K2O, CaO and MgO. Some fibers may also include silicon oxides. Many types of ceramic fibers, often well characterized with respect to composition, length and / or other properties, are available commercially. Suitable chopped ceramic fibers include but are not limited to 7000 and 6000 series fibers from Unifrax. In one example, the ceramic fibers are a high purity alumina-silica product coarsely chopped from Unifrax. Ceramic fibers may have a variety of diameters, e.g., 1.5-2.5 microns, and may be chopped to specific lengths or available in non-uniform lengths, including mixtures of shot (unfiberized material) with longer fibers. In some embodiments, a collection of ceramic fibers may contain as much as 45-55% shot. For the purposes of the present disclosure, shot, when present, is still counted as a portion of the fibrous material in the silica-containing particle composition or heat control member.

[0059] Alternatively or in addition, glass or other fibers may be used, either alone or in combination with one or more of the ceramic fibers and / or the ceramic wools, aramid and / or PBI fibers described above. Illustrative glass fibers include: borosilicate (B Fiber), acid resistant borosilicate (C Fiber), and calcium aluminoborosilicate (E Fiber), which can be obtained, for example, from Lauscha Fiber International or Unifrax, including CM-210 glass microfiber; and / or fibers that consist essentially of silica (Q fibers), which can be obtained, for example, from Johns Manville. Glass fibers may be cut to a variety of lengths, such as 3 mm, 6 mm, or 12 mm, or may be used as “shot”. Glass fibers may have a variety of diameters from 0.25 microns to 12 microns, such as from 0.25 microns to 0.5 micron, 0.5 to 1.5 microns, 1.5 to 2.5 microns, 1 micron to 5 microns or from 8 microns to 12 microns, for example, 6, 9 or 12 microns.Alternatively or in addition, more than one type of glass fiber, e.g., cut to more than one length or diameter, may be used, for example, blends of fibers with diameters less than 1 micron with fibers having diameters greater than 5 microns. Silica gel fiber is produced by spinning a gelled silica sol, for example, as described in US20200308729, the entire contents of which are incorporated herein by reference.

[0060] Other fibers that can be added to the ceramic fibers, glass fibers, ceramic wools and / or the polymeric fibers such as PBI or aramid include non-ceramic fibers such as cellulose, cotton, carbon, acrylic, polyvinyl alcohol (PVA), phenolic, polyolefin and / or other types of fibers, as well as mixtures of such fibers.

[0061] The fibers employed may be in any configuration known to those of skill in the art. For instance, the fibers may be in the form of chopped fiber, microfibers, woven fibers, or nonwoven fibers.

[0062] The shape of the fiber cross section can be round, polygonal, trilobal, pentalobal, octalobal, in the form of strips, fir trees, dumb bells, or other shape. Fibers may have consistent or varying diameters along the length of the fiber. Hollow fibers can be used in some embodiments. Additionally, the fiber materials can be smooth or crimped and may be curled or straight.

[0063] Coated fibers are employed in some embodiments. Polyester fibers metallized with a metal such as aluminum are one example.

[0064] Also suitable are fibers modified by additives. Examples of such additives include but are not limited to: anti-static agents such as carbon black, for instance; and / or IR opacifiers (typically used to reduce the radiation contribution to thermal conductivity) such as carbon black, titanium dioxide, alumina, iron oxide, or zirconium dioxide, silicon carbide, or any mixtures thereof.

[0065] In addition to including IR opacifiers, the radiation contribution to the thermal conductivity can be further reduced by using blackened fibers, such as polyester fibers blackened with carbon black or simply carbon fibers.

[0066] The amount of the fibrous component (either one fiber or a blend of fibers) used depends on its density, diameter, length, etc. and can be from 1 wt% to 99 wt%, preferably 5 to 55 wt%, for example, 10-50 wt%, 15-40 wt%, 20 to 35 wt%, or 10 to 30 wt%. with respect to the weight of the silica-containing particle composition and / or heat control article. In specificembodiments, the mass ratio of the silica-containing particulate component (total aerogel + hydrophobic silica-containing aciniform particle) to the fibrous component is within a range of from 1: 10 to 10:1, preferably 1:3 to 10: 1 by weight, e.g., from 1:2 to 10: 1, from 1 :3 to 3: 1, from 1 :2 to 2: 1, from 1 : 1 to 10: 1, from 1.2: 1 to 9:1, from 1 :2 to 9: 1, or from 1 : 1 to 5: 1. When the relative amount of fibrous component is too great, the thermal conductivity of the silica- containing particle composition and / or heat control article may be too high. When the relative amount of fibrous component is too small, the tensile strength of the silica-containing particle composition and / or heat control article may be too low.

[0067] Blends of fibers may also be used. For example, a first fiber that is selected to provide mechanical strength may be used in combination with a second fiber that functions to retain the silica-containing particles and other particulates such as opacifiers in the blanket. The first fiber is typically a glass or ceramic fiber, while the second fiber is typically a fiber with a higher aspect ratio but may be a longer glass or ceramic fiber. Alternatively or in addition, a third fiber may be included to enhance particular mechanical properties. For example, addition of polymer fibers as the third fiber may enhance the flexibility of the resulting composition or heat control article.

[0068] While the wools and / or temperature resistant polymeric fibers described herein could represent the entire fiber component in the composition, they are often used in conjunction with glass or ceramic fibers. In many cases, the glass or ceramic fibers may actually represent the major fibrous ingredient (more than 50% by weight relative to the total weight of the fibrous component) and can be thought of as the “primary” fiber employed in the composition. In such situations, the term “secondary” can be applied to the ceramic wools and / or the temperature resistant polymeric fibers (e.g., PBI, aramid) in the composition. Alternatively, PBI or aramid fibers may represent the major fibrous ingredient. Alternatively or in addition, blends of glass and ceramic fibers may also be used (e.g., with ceramic or glass as the primary fiber and the other as the secondary fiber), and, in general, any of the fibers or wools disclosed herein may be combined with one or more of the others. In certain embodiments, the ratio of primary fibers and secondary fibers by weight is 100: 1 to 1 : 100, for example, 50:1 to 1 :50, 35: 1 to 1 :35, 25: 1 to 1 :25, 15: 1 to 1 :15, 10: 1 to 1 : 10, 7: 1 to 1 :7, 5: 1 to 1 :5, 4: 1 to 1 :4, 3: 1 to 1 :3, or 2:1 to 1 :2. In specific implementations, glass or ceramic fibers are used alone or in weight ratios from 1:4 to 10: 1 with aramid fibers, for example, from 1 :3 to 5: 1, from 1 :2 to 3: 1, or from 1 : 1 to 2: 1.Alternatively or in addition, different types of glass fibers, for example glass fibers having a diameter of 5-10 microns are used in combination with glass microfibers having a diameter of less than one micron in a weight ratio (larger diameter: smaller diameter) of 5: 1 to 1 :5, for example, 4: 1 to 1 :4, 2: 1 to 1 :2, or 1 :5 to 1 to 1 : 1.5. Alternatively or in addition, ceramic microfibers are the primary fiber and glass fibers or microfibers are the secondary fiber. Alternatively or in addition, combinations of three or more types of fibers are used, for example, ceramic microfibers (less than 5 microns in diameter, or less than 3 microns in diameter), are used in combination with two or more of glass fibers having a diameter of 5-10 microns, glass fibers having a diameter of less than five microns or less than 1 micron, aramid fibers, and PBI fibers. Alternatively or in addition, glass fibers used in fabrication of the silica-containing particle compositions or heat control members are chopped to 6 microns or less or 3 microns or less.

[0069] The length and diameter of the fibers, e.g., glass or ceramic fibers, can vary with the specific application. Thinner fibers such as microfibers (diameter less than 5 microns or less than 1 micron), for example, can add flexibility, while the length and / or distribution of the fibers can play a role in increasing the mechanical strength of the final product, a blanket, for example. In illustrative examples, fibers are cut to lengths of 3 mm, 6mm, or 12 mm or other commercially available lengths. Two or more different types of fibers or fibers made of the same material but characterized by different fiber lengths, length distribution, diameter, or diameter distribution can be used to obtain a bimodal or multimodal length or diameter distribution of fibers.

[0070] In some embodiments, the composition and / or heat control article includes elastomeric particles, for example, silicone particles, rubber powder, or thermoplastic microspheres. Such materials are believed to potentially improve both the reinforcement and elasticity of the finished article, e.g., a blanket. Elastomeric particles may be solid, hollow, and / or resin coated. For the purposes of the present description, elastomeric powders or particles are categorized with the other particulate components of the composition such as opacifiers, and not with the polymeric components such as dispersants, surfactants, flocculation aids, defoamers, and binders.

[0071] Silicone powders or particles of various average particle size (avg PS), e.g., within a range of from about 1 micron to 1 mm in diameter, are commercially available. As one example, a supplier such as Shin Etsu Silicones, provides suitable elastic particles under their SiliconePowder KMP series. For instance, particles with an avg PS of 13 gm are available under product code KMP-598, while product KMP-402 provides a PS = 30 gm.

[0072] In many embodiments, the compositions described herein include opacifiers, such as infrared (IR) opacifiers, to reduce radiative heat transfer. These materials reduce the transmission of infrared radiation and can include, for instance, carbon black, mica, alumina, graphite, titanium dioxide, rutile sand, iron oxide, silicon carbide (SiC), graphite or zirconium dioxide. Some suitable types of titanium dioxide include, for example, Tipure® (DuPont) and Altiris® (Huntsman). IR opacifiers may be used individually or as mixtures of two or more compounds. The size of the particles may be selected to reflect particular wavelengths. For example, for ceramic opacifiers such as titanium dioxide, particles less than 1 micron as measured by laser diffraction may block visible light more efficiently than IR radiation, while thermal conductivity of the particles may increase at larger particles sizes, e.g., greater than 3 microns. In another example, silicon carbide is available with grit sizes (Federation of European Producers of Adhesives) from F230 to F2000, for example, F500, F600, F800, F1000, F1200, and Fl 500.

[0073] IR opacifiers can be added in amounts selected to provide a target level of IR transmission reduction in the silica-containing particle composition and / or heat control article (e.g., blanket). Illustrative such levels may be, for example, up to 10%, 0.5% to 8%, 0.75% to 5%, or 1% to 3% opacifier based on the total mass of the silica-containing particle composition and / or heat control article. Adding opacifiers characterized by two or more different average particle sizes in a given composition may extend the range of IR wavelengths being covered.

[0074] In some embodiments, the silica-containing particle composition and / or heat control article (e.g., blanket) can include a flame or fire retardant. Flame retardants may be, for example, alkali oxides, alkali earth metal oxides, aluminum trihydrate, magnesium hydroxide, antimony oxides, titanium dioxide, rutile sand, melamine compounds, phosphate based or halogen based compounds. In specific embodiments, titanium dioxide particles may have a diameter of about 1.18 gm as measured by laser diffrati on, from 0.9 to 1.3 gm, from 0.8 to 1.4 gm or from 0.5 to 4.0 gm, and in certain embodiments the particle size distribution may have a d50 of about 1.0 gm+ / -0.01 pm, + / -0.02 gm or + / -0.05 gm. Halogenated flame retardants include, for example, brominated flame retardants (BFR) such as organobromide compounds including polymeric organobromide compounds. In another set of embodiments, a polymeric flame retardant has astructure with a high ratio of heteroatoms to carbon atoms. For example, in some embodiments the ratio of heteroatoms to carbon atoms may be greater than 0.5 to 1, greater than 1 to 1, or greater than 2 to 1, and in specific embodiments the heteroatoms may be nitrogen and / or sulfur. Flame and / or fire retardants can be incorporated into the silica-containing particle composition and / or heat control article in concentrations adequate to suppress flammability or to meet specifications such as UL94-V0. Alternatively or in addition, exemplary silica-containing particle compositions and / or heat control articles may exhibit caloric content of, for example, less than 10 MJ / kg, less than 8 MJ / kg, less than 5 MJ / kg, less than 3 MJ / kg, less than 2 MJ / kg, or less than 1 MJ / kg, for example, from 0.5 MJ / kg or 1 MJ / kg to 5 MJ / kg.

[0075] Concentrations of fire and / or flame retardant that can be employed may range, by weight, from 0.1% to 5.0%, 0.2% to 2.0%, and 0.3% to 1.5% with respect to the mass of the silica- containing particle composition and / or heat control article. In specific implementations, the flame or fire retardant is combined with the silica-containing particles, e.g., with a mixture containing silica-containing aciniform particles and optionally aerogel particles.

[0076] Heat absorbing materials or phase change materials also can be employed. Such materials help the silica-containing particle composition and / or heat control article (e.g., blanket) behave not only as an insulator, retarding heat transfer, but as a heat capacitor which can store thermal energy. Such heat absorbing materials may include aluminum hydroxide and others known to those of skill in the art. Alternatively or in addition, heat absorbing materials may include phase change materials that store heat by undergoing a thermodynamic phase transformation or a change in hydration state or crystalline structure. Suitable phase change materials include both organic materials and inorganic materials such as metals, inorganic salts, and inorganic hydrated salts. Heat absorbing materials can be combined with silica-containing particles or can be deposited on the surface of or otherwise impregnated into the pores of silica aerogel used in the silica-containing particle composition.

[0077] The compositions can optionally include a binder. In some situations, the binder can help prevent widespread dispersion or dissipation of the silica aerogel, hydrophobic silica- containing aciniform particles, and / or other particulate components of the silica-containing particle composition and / or heat control article, in case of a catastrophic failure or explosion of the item being insulated, e.g., a battery. Examples of suitable binders include but are not limited to silicone, polyurethane, epoxy, polyvinyl alcohol, polyvinylidene fluoride, polyethyleneterephthalate, polybutylene terephthalate, acrylate (acrylic) polymers, and so forth. Binders that include heat resistant and / or flame retardant polymers are preferred. A binder such as polyvinyl alcohol, silicone, polyurethane, styrene butadiene polymers, or an acrylate or acrylic polymer can also bind additives such as carbon black to silica-containing particles to alleviate dusting during downstream processing of the silica-containing particle composition. Exemplary commercially available binders include Joncryl FLX5201, FLX5220, FLX5026A and 1670 polymers from BASF, U4000, U4101, and APU 10120 polymers from Alberdingk Boley, Novacryl PSR300 polymer from Synthomer, and Styrofan 4306 polymer from BASF. Binders may be mixed with a portion or all the components of the mixture, including any additives incorporated into the mixture, using an impeller or other suitable apparatus known to those of skill in the art. Preferably, the binder does not render the silica-containing particle composition flammable under UL94 or other flammability test methods.

[0078] Processing aids also can be included. The processing aid(s) chosen will depend on the manufacturing method and form of the silica-containing particle composition and / or heat control article. Suitable processing aids include but are not limited to defoamers, surfactants, dispersants, and emulsifiers.

[0079] Various commercial defoamers are known to those of skill in the art and are suitable for use with the silica-containing particle compositions herein. The defoamer may be a polyol or a polyglycol, e.g., available under the Surfynol name from Evonik Industries. Alternative polyols include but are not limited to 1,3 -propanediol, 1,2-butanediol, 2, 3 -butanediol, 1,3 -butanediol, 1,4-butanediol, glycerol, trimethylolpropane, pentaerythritol, triethanolamine and trihydroxymethyl aminomethane. Alternatively or in addition, an oil-based or a fatty acid based defoamer may be employed. Alternatively or in addition, the defoamer may be a polymer based defoamer, e.g., a silicone based defoamer, such as Dehydran 1293 defoamer from BASF.

[0080] A dispersant or surfactant may be selected from ionic (anionic and cationic) surfactants and dispersants, amphoteric surfactants and dispersants, nonionic surfactants and dispersants, and high molecular weight surfactants and dispersants, for example. Suitable anionic surfactants include alkyl sulfates and higher alkyl ether sulfates, more specifically, ammonium lauryl sulfate, and sodium polyoxyethylene lauryl ether sulfate, for example. Suitable cationic surfactants include aliphatic ammonium salts and amine salts, more specifically, alkyl trimethylammonium, and polyoxyethylene alkyl amine, for example. The amphotericsurfactants may be of betain type, such as alkyl dimethyl betain, or of oxido type, such as alkyl dimethyl amine oxido, for example.

[0081] Suitable nonionic dispersants include, for example, glycerol fatty acid ester, propylene glycol fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, tetraoleic acid polyoxyethylene sorbitol, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxypropylene alkyl ether, polyethylene glycol fatty acid ester, higher fatty acid alcohol ester, polyhydric alcohol fatty acid ester, polyether-modified poly dimethyl siloxanes, and others.

[0082] Additional potential surfactants include AEROSOL OT (sodium di-2- ethylhexylsulfosuccinite), BARLOX 12 (a branched alkyldimethylamine oxide), BARLOX 12i (a branched alkyldimethylamine oxide), TRITON 100 (octylphenoxypolyethoxy(9- 10)ethanol), TWEEN surfactants like TWEEN 100 surfactant, and BASF pluronic surfactants. Other examples of wetting agents include glycols, alkoxylates polyoxyalkylene fatty ethers, such as polyoxyethylene fatty ethers, sorbitan esters, mono and diglycerides, polyoxyethylene sorbitol esters, polymeric surfactants like Hypermen polymer surfactants, sodium coco-PG-dimonium chloride phosphate and coamidopropyl PG-dimonium chloride phosphate, phosphate esters, polyoxyethylene (POE) fatty acid esters, Renex nonionic surfactants (nonionic esters formed by reaction of ethylene oxide and unsaturated fatty acids and heterocyclic resin acids.), alcohol ethoxylates, alcohol alkoxylates, ethylene oxide / propylene oxide block copolymers, polyoxyethylene derivatives of sorbitan esters or combinations thereof. Preferred dispersants have at least one cationic or cationizable group and an HLB ratio of 2 to 20, more preferably ethylene oxide and propylene oxide oligomers in a molar ratio of ethylene oxide mers and propylene oxide mers from 0.1 : 1 to 11 : 1. Exemplary dispersants include but are not limited to Jeffamine M-2070 compound (Huntsman), a monofunctional, primary amine with a weight average molecular weight of about 2,000 and a propylene oxide / ethylene oxide (EO / PO) mol ratio of 31 / 10 and an HLB value of 13.8, Jeffamine M600 compound (Huntsman), a monofunctional, primary amine with a weight average molecular weight of about 600 and a propylene oxide / ethylene oxide (EO / PO) mol ratio of 1 / 9 and an HLB value of 2, Jeffamine ED900 compound (Huntsman), a difunctional primary amine with an EO / PO ratio just greater than 2 and a weight average molecular weight of about 900, Surfonamine L-300 compound (Huntsman), a monofunctional, primary amine with a EO / PO ratio of about 58 / 8, a weightaverage molecular weight of about 3000 and an HLB of about 17.1, and Surfonamine B-200 compound, a monofunctional, primary amine with an EO / PO ratio of about 6 / 29 and a weight average molecular weight of about 2000.

[0083] While in many cases ingredients can be combined in any suitable manner, techniques for incorporating some of the components can benefit from additional consideration. With fibers, for example, too little mixing energy can lead to undispersed bundles of fibers that do not efficiently improve performance. Overdispersion (under unrestrained length of mixing or mixing energy), on the other hand, can lead to self-entanglement and “balling”. Too much chopping and cutting energy can result in reducing the length of the fiber to a less than ideal length, affecting product attributes or performance. As for equipment, it was found that mixing operations that rely on a cutting blade with a sharp leading edge can also contribute to fiber length reductions. While on a short time scale this could be relatively benign, the effect is expected to accelerate over longer periods.

[0084] It was also found that certain properties of the material being incorporated can render the material more susceptible to “overprocessing” effects. In the case of fibers, for example, such effects become more significant for fiber lengths greater than about 6 mm (0.25 inch) and / or fine coarseness.

[0085] Thus, some embodiments described herein relate to controlling some of the mixing parameters such as time of mixing, energy supplied, type of equipment, e.g., blade type. In specific examples, mixing parameters take into account properties of the material being processed. In others, properties of the material are evaluated, then correlated to suitable mixing parameters. Establishing suitable mixing parameters can be based on routine experimentation, prior experience, and so forth.

[0086] To form the composition described herein, ingredients can be combined in any suitable manner and can involve a single step. In many cases, however, mixing is performed in a sequence of two or more steps, using equipment known in the art. In one example, silica- containing particles and fibers are added to a solution containing processing aids such as defoamers, surfactants, dispersants, and / or emulsifiers.

[0087] In some embodiments, the mixture is encapsulated in an envelope. The envelope may serve to prevent dusting, help maintain the shape of the heat control member, facilitate manipulation or installation of the heat control member, and / or serve other useful functionsknown to those of skill in the art. The material that forms the envelope is preferably a flame retardant and / or heat resistant polymer. Exemplary polymers include silicones, polyvinylidene fluoride (PVDF), chlorinated polyethylene, and other similar polymers known to those of skill in the art. Alternatively or in addition, the material for the envelope may include a reinforcing fiber such as an aramid fiber to provide puncture resistance. A reinforcing material may be used in combination with other polymers or the envelope may be formed entirely of such polymers, e g., a woven cloth of aramid fiber.

[0088] The heat control article may take any form known to those of skill in the art. For example, an silica-containing particle composition such as a fiber-containing blanket or pad can be made using techniques such as those described in, e.g., US9399864, US20210363699, W02022024085, CN112759353, US11274044, CN112681009, CN113943171, CN110093783, CN112681009, JP2015048543, and / or US20200295328, the contents of all of which are incorporated herein by reference.

[0089] Generally, in a “wet laid” process, the silica-containing particles and optional materials are flocculated from an aqueous slurry to form a substantially stable homogeneous suspension of particles (floc). Preferably, the aqueous slurry includes less than 5% organic solvent, for example, less than 3% or less than 1% organic solvent by weight. The floc can separate from the aqueous based solvent, forming a two-phase system consisting of flocculated particles floating above a surnatant of substantially water. The floc may float on top of the surnatant, or a portion of the floc may be suspended in the surnatant. The flocculated material can support an even distribution of the different particles from which the blanket can be made. This stable, consistent distribution of particles can provide blanket that exhibits a uniform composition throughout.

[0090] In one embodiment, such as described in US9399864, an aqueous slurry is prepared with the mixture of silica aerogel, hydrophobic silica-containing particles, ceramic fibers, and other components (e g., binders, opacifiers, fire retardants, defoamers, etc ). Preferably, the relative amount of the various components in the aqueous slurry corresponds to their relative amounts in the silica-containing particle composition. A charged compound or other emulsifier or dispersant is included in the slurry to create an emulsion, which is then coagulated with a flocculating agent. The resulting floc is collected on a scrim or belt and dewatered. The thickness of the silica-containing particle composition may be adjusted by increasing ordecreasing the solids loading of the aqueous slurry. In some embodiments, the solids loading may be from 5% to 25% of the aqueous slurry by weight, for example, from 5-10%, from 10 to 15%, from 15-20%, or from 20-25% by weight.

[0091] Without being bound by any particular theory, it is believed that as the flocculation becomes more efficient, the various particles are able to pack more densely in the blanket. Flocculation agents preferably are able to flocculate sufficient solids in the mixture such that the bulk of the solids float to the top of the aqueous mixture, leaving the aqueous media relatively clear, rather than cloudy. Preferred flocculation agents are polymeric flocculation agents, in contrast to inorganic flocculation agents. Exemplary polymeric flocculation agents include quaternary polyamines such as polyamine, e.g., SuperFloc® 577 or 581 flocculant from Kemira, and polyacrylamides such as Nal clear 7768, Nalclear 8187, and Nalclear 8176 polymers from Nalco, dicyandiamide resins, polydiallyldimethylammonium chloride (PDADMAC), amino silanes, quaternary amine-functionalized silanes, silicone resins, and mixtures or emulsions of any of these. In some embodiments the flocculation agent is in the form of a latex, or an aqueous emulsion of the flocculation agent. Flocculation agents may have a variety of number average molecular weights, e.g., from 400 to 60,000,000, preferably from 400 to 1,000,000, for example, from 5000 to 10,000, from 10,000 to 100,000, from 100,000 to 500,000, from 500,000 to 1,000,000, from 20,000 to 10,000,000, from 1,000,000 to 30,000,000, or from 5,000,000 to 50,000,000.

[0092] Flocculation agents may be used in conjunction with a flocculation polymer. The flocculation agent is preferably an ionic polymer; the flocculation polymer is preferably an ionic polymer of the opposite charge. In some embodiments the flocculation polymer is in the form of a latex, or an aqueous emulsion of the flocculation polymer. The flocculation polymer may have a number average molecular weight of 400 to 1,000,000, for example, from 5000 to 10,000, from 10,000 to 500,000, from 20,000 to 50,000, or from 50,000 to 1,000,000. Alternatively, the flocculation polymer may have a molecular weight in the range described above for the flocculation agent. Suitable flocculation polymers include but are not limited to natural and synthetic latex polymers, acrylics, and polyacrylamides. As the flocculation agent is preferably a charged polymer, any of the agents listed above as a flocculation agent may also be employed as a flocculation polymer depending on the relative charge. Critically, only one component of a flocculation system (here termed the flocculation polymer) is added to the aqueous slurrybefore or while the other components (particles, fiber, opacifier, etc.) are added, while the flocculation agent is only added after all the other components are combined. Preferably, the flocculation agent and the flocculation polymer are used in amounts such that the amount of charge provided by the flocculation agent (i.e., the charge density times the mass) is within 20% of the amount of charge provided by the flocculation polymer, for example, within 10%, within 5%, or within 1%.

[0093] The total amount of flocculation agent and flocculation polymer together should be sufficient to bind the various components of the silica-containing particle composition, but not so great that they fill the pores of the silica-containing particle composition, thus degrading the thermal conductivity performance. Indeed, in certain embodiments, the flocculation agent and flocculation polymer may provide all the binding function required in the silica-containing particle composition, obviating the use of a binder. Use of greater than the necessary amount of flocculation agent and flocculation polymer may also undesirably influence the mechanical performance of the composition, undesirably increase the density, increase caloric content of the silica-containing particle composition, or degrade flammability performance. The total weight fraction of polymer, including dispersant, binder, defoamer, flocculation agent, and flocculation polymer, used to produce the silica-containing particle composition may be less than 25%, for example, from 3 to 25%, e.g., from 4 wt% to 10 wt%, from 10 wt% to 15 wt%, from 15 wt% to 20 wt%, or from 20 wt% to 25 wt% based on the total weight of material added to the aqueous solvent, that is, the total weight of material in the floc and the surnatant but excluding the aqueous solvent. Where a binder is not used, the amount may be even smaller, e g., from 3 wt% to 15 wt% or from 8 wt% to 17 wt% based on the total weight of material added to the aqueous solvent to form the silica-containing particle composition. The same proportions of polymer may be found in the resulting silica-containing particle composition. Likewise, the total weight of polymer, including dispersant, binder, defoamer, flocculation agent, and flocculation polymer, in the resulting silica-containing particle composition may be less than 25%, for example, from 3 to 25%, e g., from 4 wt% to 10 wt%, from 10 wt% to 15 wt%, from 15 wt% to 20 wt%, or from 20 wt% to 25 wt% based on the total weight of the silica- containing particle composition. Where a binder is not used, the amount may be even smaller, e g., from 3 wt% to 15 wt% or from 8 wt% to 17 wt% based on the total weight of the silica- containing particle composition.

[0094] Threshold amounts of dispersant, defoamer, flocculation agent and flocculation polymer are required to form a cohesive silica-containing particle composition using a wet laid method. One of skill in the art will recognize that the required amount will vary depending on the relative amounts of the non-polymer components (particles, fiber, opacifier, fire retardant, heat absorbing material, etc.). However, excess material can be detrimental to the thermal conductivity and / or flame retardance according to UL-94 and can undesirably increase the density. In certain embodiments, the total amount of flocculation system (i.e., flocculation agent and flocculation polymer) and binder used to produce the silica-containing particle composition or heat control article is 3-20% by weight, for example, 4-16% by weight, based on the total weight of material in the floc and the surnatant but excluding the aqueous solvent. Likewise, the total amount of flocculation system and binder in the silica-containing particle composition may be 3-20% by weight, for example, 4-16% by weight, based on the total weight of the silica- containing particle composition.

[0095] In certain embodiments, the packing density of the various components may be increased by using compression to pressing additional water out of the floc prior to drying. For example, the floc may be passed through a two-roll press or pressed between two plates or platens. Alternatively, a single roller may be passed over the floc. Pressing increases the packing density of the various components by squeezing water from the floc. In the final product, this reduces interparticle porosity as the remaining water is replaced by air during drying. Alternatively or in addition, any of these methods may be used to compress the silica-containing particle composition after it is dried. Following drying, compression may be used to make the composition thinner and denser, allowing the silica-containing particle composition and / or heat control member to take up less space and also improving mechanical properties. The density of the silica-containing particle composition or heat control member may be 0.1 to 0.6 g / cm3, for example, 0.15 to 0.5 g / cm3, 0.15 to 0.4 g / cm3, or 0.2 to 0.35 g / cm3.

[0096] In another embodiment, aerogel, hydrophobic silica-containing aciniform particles, fiber, a binder, and any other desired components are charged into a mold and pressed into a pad, for example, as described in EP3835262, the entire contents of which are incorporated by reference herein. It may be necessary to heat or otherwise activate a polymeric binder in the mold. Alternatively or in addition, aerogel, hydrophobic silica-containing aciniform particles, and other components may be formulated into a paste and extruded, for example, as inEP3835262 and WO2020228998, the entire contents of which are incorporated herein by reference. Alternatively, aerogel, hydrophobic silica-containing aciniform particles, and any other desired components are used to fill an envelope or other cavity using techniques such as those described in CN113785431, CN110544809, JP2012145204, and / or US20210332932, the contents of all of which are incorporated herein by reference. Alternatively or in addition, the mixture may be incorporated into or combined with a polymer foam, such as described in W02020211320, JP2020019925, and US10640629.

[0097] Another suitable technique is to charge the mixture into an envelope or bag retained in an appropriately spaced mold. The mold is compressed by hand, e.g., using clamps, and then preferably evacuated. For thinner envelopes, it may be desirable to use a smaller diameter aerogel to facilitate free flow throughout the bag. Alternatively, the mass of material needed to produce a desired mass density in an envelope or pouch having a particular volume may simply be charged into the envelope without the use of a mold. The envelope may then be compressed with a roller to evenly distribute the mixture throughout the bag. In a preferred embodiment, a film or sheet, e g., of polyethylene terephthalate or silicone, is laid in a mold on a vibration table and the mixture charged into the mold having a cavity, with a portion of the film or sheet overhanging beyond the cavity. The mold is vibrated and compressed with a plate at 8-12 psi to pack the mixture. A top sheet (or film) large enough to cover the cavity and the overhanging portions is laid on top and the overhanging portion sealed with the top sheet on three sides. Air is evacuated from the resulting envelope and the fourth side is sealed. Indeed, certain components, such as fibers and binders, may not be necessary if the envelope provides desired mechanical support. Indeed, in some embodiments it may be desirable only to have aerogel along with any optional opacifier and / or hydrophobic silica containing particles in the envelope.

[0098] The heat control article (a blanket, for instance) comprising the silica-containing particle composition may be fabricated in roughly planar or flat form for insertion between cells of a rechargeable battery, e.g., a lithium ion battery. In other approaches, the article can be prepared in another desired shape. An evacuated envelope can be slightly thinner than the space in which it will be installed. Once installed, the envelope can be poked to release the vacuum and will expand until it is under compression. As the battery expands and contracts, the heat control member would also be free to expand and contract. Alternatively or in addition, the envelope need not be fabricated as a flat or sheet-like object but may be fabricated in a particular shape.For example, the heat control article may be shaped to be disposed about a particular component in a battery or other device and may have a more complicated shape.

[0099] In some embodiments, the silica-containing particle composition is fabricated to the correct size or cut to the desired size of the heat control article. Alternatively or in addition, the heat control article includes an additional sheet-like material to enhance mechanical integrity, heat resistance, mechanical resilience, and / or other properties. Examples include but are not limited to silicone-based materials, polyvinylidene fluoride, chlorinated polyethylene, aramid materials such as Kevlar (e.g., woven mats of aramid fibers), and Kevlar nanofiber aerogels such as those described in Lyu, et al., ACS Nano 2019, 13, 2236-2245. Woven mats of Kevlar or other aramid fibers may be impregnated with a shear thickening fluid such as those described in US 7,825,045, the contents of which are incorporated herein by reference.

[0100] An envelope can be used in some cases, serving to prevent dusting, help maintain the shape of the heat control article, facilitate its manipulation or installation, and so forth. The material that forms the envelope is preferably a flame retardant and / or heat resistant polymeric material, including, for instance, silicones, polyvinylidene fluoride (PVDF), polyethylene terephthalate (PET), chlorinated polyethylene, and other similar polymers known to those of skill in the art. Alternatively, or in addition, the material for the envelope may include a reinforcing fiber such as an aramid fiber to provide puncture resistance. A reinforcing material may be used in combination with other polymers or the envelope may be formed entirely of such polymers, e.g., a woven cloth of aramid fiber. In one embodiment, the envelope may comprise one or two sheets of polymer film, e.g., PET film, disposed about the two planar sides of the silica-containing particle composition. In some embodiments, a frame, e.g., of silicone rubber, may be disposed about the edges of the silica-containing particle composition and envelope to seal the envelope and ease handling of the resulting heat control article.

[0101] Alternatively or in addition, the heat control article may include several layers of the silica-containing particle composition stacked on top of one another. Optionally, the layers may be separated by any of the materials that are described above in connection with the envelope. Alternatively or in addition, the layers may be separated by foam pads or mica sheets to further improve insulation performance. Alternatively or in addition, such layers may be used on the outside of the silica-containing particle composition laminate. In some embodiments, it may be desirable to include a heat conducting material that is configured to transport heat in a controlledfashion, for example, to a heat sink. The various layers may be attached to one another by any appropriate adhesive known to those of skill in the art, needled, or encapsulated by an envelope to maintain the laminate structure.

[0102] Alternatively or in addition, the heat control article may include a coating. For example, a polymer or prepolymer solution or emulsion may be sprayed, painted, cast, or otherwise coated on one or more outside surfaces of the silica-containing particle composition or laminate and cured. Suitable cured polymers include polyolefins, silicones, polyvinyl alcohol, starches, polytetrafluoroethylene, phenolics, melamines, phenol formaldehyde, acrylic polymers and other polymers known to those of skill in the art. Such a coating can provide functionality similar to the envelope discussed above but with less material. Alternatively or in addition, the silica-containing particle composition may be surface treated, for example, it may be hydrophobized. The silica-containing particle composition may be contacted with a hydrophobizing agent such as a silane compound, a silazane compound, or a disiloxane compound. Examples of silane compounds include alkylhalosilanes having the formula RxSiX4-x and alkoxysilanes having the formula RxSi(OR )4-x wherein R is selected from the group consisting of C1-C10 branched or straight chain alkyl or alkenyl, C3-C10 cycloalkyl, and Ce-Cio aryl, preferably a C1-C4 branched or straight chain alkyl or alkenyl group, R is C1-C5 branched or straight chain alkyl, X is a halogen, preferably chlorine, and x is an integer of 1-3. The silica-containing particle composition may be immersed in the hydrophobizing agent directly or exposed to a vapor of the hydrophobizing agent. Alternatively, the silica-containing particle composition may be immersed in a mixture of the hydrophobizing agent and an appropriate solvent. The temperature and pH of the treatment media may be adjusted as known to those of skill in the art to manipulate the degree of treatment. Exemplary treatment agents include but are not limited to trimethylchlorosilane, dimethyldichlorosilane, hexamethyldisilazane, hexamethyldisiloxane, and other hydrophobizing agents known to those of skill in the art. Hydrophobizing agents are preferably water-soluble and / or have a boiling point less than 200 °C, less than 150 °C, or preferably less than 100 °C.

[0103] The silica-containing particle composition and / or heat control article may have a thickness of 0.3 to 6 mm, for example, from 0.3 to 5 mm, from 0.4 to 4 mm, from 1 to 3 mm, or from 1.5 to 2.5 mm. In some embodiments, at least a portion of the components are compressed after drying of the silica-containing particle composition, e.g., during assembly of the heatcontrol article, for example, between rollers or platens, to reduce the final thickness of the product article. Preferably, the silica-containing particle composition and / or heat control article is self-supporting. That is, the silica-containing particle composition of silica-containing particles, fibers, opacifiers and other particulate additives, and polymer binders and the flocculation system is able to be handled and manipulated without losing cohesion. Silica- containing particle compositions that are not self supporting may require a backing or scrim to maintain cohesion.

[0104] The silica-containing particle composition and / or heat control article can exhibit excellent thermal stability. For example, the heat control article may shrink less than 2% after aging at 650 °C according to ASTM-C356. The silica-containing particle composition and / or heat control article may have a thermal conductivity at 25 °C of less than 40 mW / m K, preferably less than 30 mW / m K, for example, from 5 mW / m K to 25 mW / m K or from 8 mW / m K to 15 mW / m K, or from 17 mW / m l< to 30 mW / m K, or from 15 mW / m K to 25 mW / m K, or from 20 mW / m.K to 30 mW / m.K, according to test method ASTM C518.

[0105] The silica-containing particle composition and / or heat control article may have a tensile strength of 0.5 to 1.7 MPa, for example, 0.6 to 1.5 MPa or 0.7 to 1.3 MPa.

[0106] The silica-containing particle composition and / or heat control article can be flexible, a property that may be measured according to ASTM Cl 101 or another suitable technique. Manual bending tests can be useful, especially at the initial screening stages of a product.

[0107] In specific implementations the silica-containing particle composition and / or heat control article has a flammability rating of non-flammable according to UL94-V0.

[0108] Alternatively or in addition, the silica-containing particle composition and / or heat control article may be compressible. For example, it may have a compression modulus at 50% compression of 0.1 to 100 MPa, as measured by ASTM C 165-05, for example 0.1-1 MPa, 1-10 MPa, 5-30 MPa, 10-50 MPa, or 30 to 100 MPa.

[0109] The invention is further illustrated in the following non-limiting exemplification section.EXEMPLIFICATON

[0110] Non-woven blankets containing fumed silica particles, with or without aerogel particles were produced using the materials listed in Table 1 below.Table 1

[0111] The fumed silica particles, all CAB-O-SIL brand from Cabot Corporation, are as listed in Table 2 below. Carbon content was measured using a LECO CN928 analyzer.Table 2

[0112] Insulating pads were produced as follows: Dispersant, flocculation agent, and defoamer were dispersed in water to form a one (1) Liter white (process) aqueous concentrate in a WARING benchtop heavy duty blender, according to the formulations in the examples below. Mixing was conducted for 10 sec at high shear to form process water. The concentrate was then diluted to 2.5-3 liters of water as indicated in the examples below. After mixing, approximately 1.5 Liters of the diluted process water was transferred to the Waring blender. The chopped glass fiber, aerogel particles, titania sand, silicon carbide, and aluminum trihydroxide (ATH, ThermoFisher Scientific), were added to the WARING heavy duty blender in the quantities listed in the examples. The mixture in the blender was mixed for 40 sec at high shear (15000 rpm). Glass microfibers and fumed silica were added to the blender and the mixture blended for an additional 40 s at high shear. Finally, the silicone and polyurethane binders were added and the mixture blended for an additional 20 s at high shear to make a slurry, which was added to the remaining process water. To destabilize the slurry system, the flocculation polymer was added to the slurry in the amount indicated in the examples below to produce flocs.

[0113] After flocculation, the slurry was drained through a single layer wet-lay forming wire to produce a 30cm x 30cm blanket sheet. The blanket and forming wire were then passed over vacuum to remove additional water from the floc. Samples were compressed with a heavy roller to a thickness of about 1-2 mm to squeeze out some of the water and flatten the blanket to a consistent surface. All blankets were removed from the forming wire and placed in a drying oven at 120° C for about 20min.

[0114] Sample thickness was measured with a thickness gauge. Thermal conductivity was measured at room temperature and at 140 °C using a LaserComp Heat Flow Meter instrumentaccording to ASTM C518; standard deviations represent the standard deviation from the average of two readings during a measurement. After drying, the blankets having a thickness less than 2 mm were gently pressed between two platens to flatten the surface, while blankets having a thickness greater than 2 mm were pressed between two platens at about 2 MPa at room temperature to form a thin blanket no more than 2 mm thick. The final thickness is reported in the tables below. Tensile strength (maximum load) was measured according to ASTM D5035 with three replicates.Example 1

[0115] Experiments were conducted to evaluate the properties and / or performance of several non-woven blankets containing CAB-O-SIL TS-530 fumed silica (1-1, 1-2, 1-3) and HS-5 fumed silica (1-4). All samples were prepared with 3 L of process water.Table 3

[0116] Examples 1-1, 1-2, and 1-3 how that increasing the ratio of hydrophobic fumed silica to aerogel was mildly detrimental to thermal conductivity but had a dramatic effect on tensile strength. Replacement of hydrophobic silica (1-1) with an equal amount of hydrophilic silica of moderately higher surface area (1-4) did not affect thermal conductivity but had a dramatic effect on tensile strength.Example 2

[0117] Experiments were conducted to evaluate the properties and / or performance of several non-woven blankets containing CAB-O-SIL TS-610 fumed silica. All samples were prepared with 3 L of process water.Table 4

[0118] In this experiment, improved tensile strength was achieved with a 50 / 50 (w / w) blend of aerogel and silica.Example 3

[0119] Experiments were conducted to evaluate the properties and / or performance of several non-woven blankets containing CAB-O-SIL TS-610 fumed silica while varying the ratio of fumed silica to fiber. All samples were prepared with 3 L of process water.Table 5

[0120] In this experiment, tensile strength increased as the proportion of fiber increased, but without a dramatic effect on thermal conductivity.Example 4

[0121] Experiments were conducted to evaluate the properties and / or performance of several non-woven blankets containing CAB-O-SIL TS-610 and TS-622 fumed silica. All samples were prepared with 3 L of process water; no aerogel was used in the formulation.Table 6

[0122] In this experiment, tensile strength decreased with the use of the higher surface area silica.Example 5

[0123] Experiments were conducted to evaluate the properties and / or performance of several non-woven blankets containing CAB-O-SIL M-5 fumed silica (5-1, 5-2, and 5-3) and TS-720 fumed silica (5-4). All samples were prepared with 3 L of process water.Table 7

[0124] In Examples 5-1 and 5-2, the blanket had similar thermal conductivity to blankets prepared with hydrophobic silica, but generally lower tensile strength. In Example 5-3, the blanket had lower tensile strength than Example 4-1 prepared with a similar ratio of silica to fiber and a similar fiber composition but hydrophobic silica. Substitution of hydrophilic M-5 silica with hydrophobic TS-720 silica having a methanol number greater than 70 dramatically decreased tensile strength.Example 6

[0125] Experiments were conducted to evaluate the properties and / or performance of several non-woven blankets containing CAB-O-SIL TG-5110 fumed silica. All samples were prepared with 2.5 L process water.Table 8

[0126] The examples show that with low surface area hydrophobic silica, the tensile strength actually increases with the fumed silica / aerogel ratio, with a small effect of the increased fumed silica loading on thermal conductivity.Example 7

[0127] Experiments were conducted to evaluate the properties and / or performance of several non-woven blankets containing CAB-O-SIL TG-3130 fumed silica. All samples were prepared with 2.5 L of process water.Table 9

[0128] The results show that blankets prepared with TG-3130 silica having a carbon content greater than 6 wt% exhibit dramatically lower tensile strength than blankets prepared with TG- 5110 silica having no more than 6 wt% carbon.Example 8

[0129] A bag (VacMaster Vacuum Chamber Pouch, approximately 150 mm x 200 mm with 3 mil (0.76 mm) thick walls) open at one end is placed in a mold having a 5 mm gap. The moldis prepared by clamping two pieces of3 / / ’ (19 mm) plywood, each about 9.5” (24.1 cm) square together with spacers (two paint stirrers) on either side to create an appropriately sized cavity. Either ENTERA EV5400 or ENTERA EV5200 aerogel is charged into the bag, with vibration and tamping of the mold used to ensure complete filling of the bag. The filled bag iscompressed by hand under approximately 5 psi load and then evacuated using a Vacmaster VP320 meat packer until about 90% vacuum was achieved. The evacuated pouch is expected to have a thermal conductivity of 14-17 mW / m.K and a thickness of 5-7 mm. The same procedure was used to fill the same design of bag with a 50 / 50 (w / w) mixture of ENTERA EV5200 aerogel and TS-530 fumed silica. The evacuated pouch has a thermal conductivity of 9.3 mW / m.K.

[0130] The same design of bag is filled with a predetermined weight of ENTERA EV5400 aerogel. The desired weight is that which is needed to achieve an end density of 110 kg / m3in a 150mmx200mmx4mm pouch. The bag is then compressed by hand under a roller using two rails to maintain the desired thickness of the filled bag at about 5mm. The roller is rolled back and forth until the aerogel appears to be evenly dispersed. The pack is then placed in the Vacmaster VP320 meat packer and evacuated. The thermal conductivity is expected to be 14- 17 mW / m.K.

[0131] While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A composition comprising a mixture of a) silica aerogel particles having particle sizes in a range from 0.1 mm to 5 mm and b) hydrophobic silica-containing aciniform particles having a carbon content up to 6% and a methanol number of 30 to 70; wherein the silica aerogel particles and hydrophobic silica containing particles are present in a ratio from 0: 100 to 80:20; and wherein the composition has a thermal conductivity at 25 °C of approximately 5-40 mW / m.K and a thickness of 0.1-10 mm.

2. The composition of claim 1, wherein the hydrophobic silica-containing aciniform particles are selected from the group consisting of fumed silica, silicon-treated carbon black, silica-coated carbon black, fumed mixed metal oxides, and silica-carbon black composite particles.

3. The composition of any of the preceding claims, wherein the hydrophobic silica- containing particles are hydrophobic fumed silica.

4. The composition of any of the preceding claims, wherein the hydrophobic silica- containing particles are hydrophobized by a hydrophobizing silane or a silazane.

5. The composition of any of the preceding claims, wherein the hydrophobic silica- containing particles are fumed silica particles having a surface area from 60 to 340 m2 / g, preferably from 60 to 250 m2 / g surface treated with a silica-treating agent.

6. The composition of any of the preceding claims wherein the hydrophobic fumed silica has a methanol number of 45 to 70.

7. The composition of any of the preceding claims, wherein the hydrophobizing silane is R 4-nSiX n wherein n is 1-3, each R is independently selected from the group consisting of hydrogen, a C1-C30 branched or straight chain alkyl or alkenyl group, a C3-C18 haloalkyl group, C3-C10 cycloalkyl, and a C6-C14 aromatic group, and each X is independently a Cl -Cl 8 branched or straight chain alkoxy group or halo.

8. The composition of any of the preceding claims, wherein the hydrophobizing silane is R 4-nSiXnwherein n is 1-3, each R is independently selected from the group consisting of hydrogen and a C1-C4 branched or straight chain alkyl or alkenyl group, and each X is independently a C1-C18 branched or straight chain alkoxy group or halo.

9. The composition of claim 7 or claim 8, wherein no more than three groups R are hydrogen.

10. The composition of any of the preceding claims, wherein the mixture further comprises fibers.

11. The composition of any of the preceding claims, wherein the fibers are glass fibers, ceramic fibers, synthetic polymer fibers, carbon fiber, natural polymer fibers, mineral wool, or a mixture of two or more of these.

12. The composition of any of the preceding claims, wherein the fibers are blackened or coated with a metal.

13. The composition of any of the preceding claims, wherein at least a portion of the silica aerogel present in the heat control member incorporates an opacifier.

14. The composition of any of the preceding claims, wherein at least a portion of the silica aerogel is coated with or impregnated with a heat absorbing material.

15. The composition of any of the preceding claims, wherein the mixture further comprises one or more components selected from the group consisting of fiber, opacifier, fire retardant, heat absorbing material, phase change material, binder, defoamer, dispersant, emulsifier, surfactant, and flocculant.

16. The composition of any of the preceding claims, further comprising a sheet or mat comprising silicone, polyvinylidene fluoride, chlorinated polyethylene, aramid fibers, or aramid aerogel.

17. The composition of any of the preceding claims, further comprising an envelope encapsulating the mixture.

18. A heat control member comprising the composition of any of the preceding claims.

19. The heat control member of claim 18, wherein the heat control member is in the form of a blanket or pressed pad.

20. The heat control member of claim 18 or claim 19, wherein the heat control member meets the specifications of UL94 VO.

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