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EP-4587628-B1 - AEROGEL COMPOSITION FOR THERMAL INSULATION

EP4587628B1EP 4587628 B1EP4587628 B1EP 4587628B1EP-4587628-B1

Inventors

  • ZHANG, XIAOFENG
  • SULLIVAN, SEAN S.
  • GAMBLE, JEFFREY
  • PESCATORE, PETER F.
  • BANNON, Clare
  • CHOUDHARY, Saeed

Dates

Publication Date
20260513
Application Date
20230914

Claims (20)

  1. A heat control article in form of a nonwoven blanket, sheet, mat or pad, comprising an aerogel composition, comprising: hydrophobic silica aerogel particles; a fibrous component that includes one or more materials selected from the group consisting of polymer fibers and inorganic fibers, wherein the ratio of the aerogel particles:fibrous component is from 1:3 to 10:1 by weight; and 3- 25 % of polymer by weight, based on the total weight of the composition, wherein the composition has a thickness of 0.3 to 6 mm, a thermal conductivity up to 32 mW/m.K at 25 °C, a UL-94 rating of V0, a tensile strength from 0.09 to 5 MPa, and a density of 0.1-0.6 g/cm 3 .
  2. The heat control article of claim 1, wherein the composition comprises 15-65% by weight of aerogel particles.
  3. The heat control article of any of claims 1-2, wherein the fibrous component is present in an amount from 5 to 55 wt%.
  4. The heat control article of any of claims 1-3, wherein the fibrous component comprises a blend of a primary fiber comprising glass fibers or ceramic fibers and one or more secondary fibers selected from the group consisting of ceramic wool, glass fibers, ceramic fibers, aramid fibers, PBI fibers, cellulose fibers, cotton fibers, carbon fibers, acrylic fibers, polyvinyl alcohol (PVA) fibers, phenolic fibers, polyolefin fibers, and mixtures of any of the above.
  5. The heat control article of any of claims 1-4, further comprising one or more of a fire retardant, a flame retardant, a heat absorbing material, or a phase change material, or an opacifier selected from the group consisting of carbon black, mica, alumina, graphite, titanium dioxide, rutile sand, iron oxide, silicon carbide (SiC), graphite, zirconium dioxide, and combinations of two or more of these.
  6. The heat control article of any of claims 1-5, wherein the polymer comprises a surfactant, a dispersant, or both.
  7. The heat control article of any of claims 1-6, wherein the polymer comprises a binder selected from the group consisting of silicone, polyurethane, polyvinyl alcohol, polyvinylidene fluoride, polyethylene terephthalate, polybutylene terephthalate, styrene-butadiene copolymers, and acrylate (acrylic) polymers.
  8. The heat control article of any of claims 1-7, wherein the polymer comprises a flocculation system comprising a flocculation agent and a flocculation polymer, an optional binder, a dispersant, and an optional defoaming agent, wherein the total amount of flocculation system and optional binder in the composition is from 3 to 20% by weight.
  9. The heat control article of any of claims 1-8, wherein a) the heat control article further comprises one or more layers independently comprising a woven polymer mat, a foam pad, a mica sheet, or a heat conducting material, b) at least one surface of the heat control article is covered with a polymer film, wherein the polymer is selected from a silicone polymer, polyvinylidene fluoride, polyethylene terephthalate, and chlorinated polyethylene, the polymer film optionally comprising a reinforcing fiber, or both.
  10. A method of making a heat control article in form of a nonwoven blanket, sheet, mat or pad, comprising a nonwoven aerogel composition, the method comprising: mixing hydrophobic silica aerogel particles, a fibrous component, at least one polymeric component, and an aqueous solvent to form an aqueous slurry, wherein the ratio of the aerogel particles:fibrous component is from 1:3 to 10:1 by weight; flocculating and/or coagulating the aqueous slurry to form a floc, the floc comprising at least a portion of the aerogel particles, fibrous component, and polymeric component, and a surnatant; dewatering the floc; and drying the floc to produce the nonwoven aerogel composition having a thickness of 0.3 to 6 mm, a thermal conductivity up to 32 mW/m.K at 25 °C, a UL-94 rating of V0, a tensile strength from 0.09 to 5 MPa, and a density of 0.1-0.6 g/cm 3 , wherein the total amount of polymeric component in the floc and the surnatant is from 3-25% based on the total amount of material in the floc and the surnatant excluding the aqueous solvent.
  11. The method of claim 10, wherein the total amount of solid material, including the polymeric component, in the aqueous slurry is from 5% to 25% by weight.
  12. The method of any of claims 10-11, further comprising compressing the dewatered floc or the nonwoven aerogel blanket, or both.
  13. The method of any of claims 10-12, wherein the total amount of aerogel particles in the floc and the surnatant is 15-65% by weight excluding the aqueous solvent.
  14. The method of any of claims 10-13, wherein the fibrous component is present in the floc and the surnatant in an amount from 5 to 55 wt% excluding the aqueous solvent.
  15. The method of any of claims 10-14, wherein the fibrous component comprises a blend of a primary fiber comprising glass fibers or ceramic fibers and one or more secondary fibers selected from the group consisting of ceramic wool, glass fibers, ceramic fibers, aramid fibers, PBI fibers, cellulose fibers, cotton fibers, carbon fibers, acrylic fibers, polyvinyl alcohol (PVA) fibers, phenolic fibers, polyolefin fibers, and mixtures of any of the above.
  16. The method of any of claims 10-15, wherein mixing further comprises including one or more of a fire retardant, a flame retardant, a heat absorbing material, a phase change material, or an opacifier in the aqueous slurry, wherein the opacifier is selected from the group consisting of carbon black, mica, alumina, graphite, titanium dioxide, rutile sand, iron oxide, silicon carbide (SiC), graphite, zirconium dioxide, and combinations of two or more of these.
  17. The method of any of claims 10-16, wherein the polymeric component comprises a surfactant, a dispersant, or both.
  18. The method of any of claims 10-17, wherein the polymeric component further comprises a defoamer.
  19. The method of any of claims 10-18, wherein the polymeric component comprises a binder selected from the group consisting of silicone, polyurethane, polyvinyl alcohol, polyvinylidene fluoride, polyethylene terephthalate, polybutylene terephthalate, styrene-butadiene copolymers, and acrylate (acrylic) polymers.
  20. The method of any of claims 10-19, wherein the proportion of polymeric component by weight in the floc and the surnatant, excluding the aqueous solvent, is 4 to 20%.

Description

RELATED APPLICATIONS This application claims priority from US Provisional Applications 63/407,202, filed September 16, 2022 and 63/484,033, filed February 9, 2023. BACKGROUND OF THE INVENTION 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. 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 liquid-vapor 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. 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). 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. WO2022/024076 discloses a thermal runaway barrier for an electric vehicle battery, comprising a wet-laid nonwoven mat containing alkali silicate fibers, bicomponent fibers, adhesive and aerogel particles. Still, there is a need for a thin aerogel blanket that maintains thermal conductivity and tensile strength and has reduced amounts of components such as binders that can degrade thermal insulation performance and contribute to flammability. SUMMARY OF THE INVENTION It has been found that insulation spacers for EV applications often encounter challenges related to the tendency of battery cells to expand and contract during charging and discharging during the vehicle's lifetime. Thus, a need exists for approaches that address at least some of the issues surrounding the insulation of rechargeable batteries in electric vehicles. Particularly desired are insulating blankets that display good thermal insulation properties and various mechanical properties. For example, it is desirable that insulation spacers be sufficiently mechanically robust to withstand handling (e.g., during installation) and the mechanical challenges of operation and that they may not be too rigid or incompressible. The present invention relates to a heat control article, in the form of a nonwoven blanket, sheet, mat or pad, as defined in claim 1. The present invention further relates to a method of making a heat control article, in the form of a nonwoven blanket, sheet, mat or pad, as defined in claim 9. Particular embodiments are defined in the dependent claims. Many of the embodiments described herein relate to a heat control article that is a flexible insulating member such as, for example, a non-woven blanket, sheet, pad, mat and the like. The article can be manufactured by a wet laid technique from a composition that contains aerogel particles and other materials. In some embodiments, an aerogel composition includes aerogel particles and a fibrous component that includes one or more materials selected from the group consisting of polymer fibers and inorganic fibers. The ratio of the aerogel particles:fibrous component is from 1:3 to 10:1 by weight. The aerogel composition further includes up to 25 % of polymer by weight, based on the total weight of the composition. The composition can further include materials such as IR opacifiers, flame or fire retardants, 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. The composition can be