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EP-3778229-B1 - CONDUCTIVE COMPOSITES

EP3778229B1EP 3778229 B1EP3778229 B1EP 3778229B1EP-3778229-B1

Inventors

  • DUSTIN, ASHLEY M.
  • NOWAK, ANDREW P.
  • GUAN, XIN N.
  • GROSS, ADAM F.
  • SHARP, RICHARD E.

Dates

Publication Date
20260506
Application Date
20200812

Claims (15)

  1. A conductive composite comprising: (a) a polymer; (b) a conductor selected from metal alloys having a melting temperature below about 60°C; and (c) a compatibilizing agent, wherein the compatibilizing agent comprises a nonionic amphiphilic compound selected from the group consisting of fatty alcohol ethoxylates, alkylphenol ethoxylates, fatty acid ethoxylates, ethoxylated amines, fatty acid amides, polyoxyethylene-polyoxypropylene copolymers, fatty acid esters of polyhydroxy compounds, glycerol fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, alkyl polyglucosides, fatty amine oxides, sulfoxides, organophosphine oxides, and mixtures thereof and wherein the conductor is an alloy comprising at least about 50% by weight of gallium, bismuth, mercury, or combinations thereof.
  2. A conductive composite according to claim 1, wherein the compatibilizing agent further comprises an ionic amphiphilic compound, metallic nanoparticles, or a mixture thereof, wherein the compatibilizing agent is a compound or metal that does not alloy with the conductor when in the composite or during its manufacture.
  3. A conductive composite according to claim 2, wherein the metallic nanoparticles have a size less than 100 nm in any linear dimension and comprise copper, nickel, stainless steel, tin, titanium, tungsten, mixtures thereof, or alloys thereof.
  4. A conductive composite according to any of claims 1-5, further comprising a thickening agent.
  5. A conductive composite according to claim 4, wherein the thickening agent is an organic thickening agent.
  6. A conductive composite according to claim 4, wherein the thickening agent is an inorganic thickening agent.
  7. A conductive composite according to claim 4, wherein the thickening agent comprises rods, wires, substantially spherical particles, or a mixture thereof, and comprises a metal selected from nickel, titanium, tungsten, stainless steel, copper, tin, a metal oxide of nickel, titanium, tungsten, stainless steel, copper, tin, or zinc, ceramics, and combinations thereof, wherein the substantially spherical particles have an average size of about 0.1-500 µm as measured according to ISO13320:2020 and the rods and wires have lengths of from 0.01-10 mm and wherein the thickening agent does not dissolve the conductor or otherwise form solutions with the conductor; it remains solid when mixed with the conductor, but is wet by the conductor.
  8. A conductive composite according to any of claims 1-7, wherein the conductive composite comprises from about 0.1-50 % by volume of the conductor.
  9. A conductive composite according to any of claims 1-8 which is a laminate, wherein the conductor and compatibilizing agent are preferably uniformly mixed together and form a layer of the laminate.
  10. A conductive composite according to any of claims 1-9, wherein the conductor and the compatibilizing agent are substantially uniformly dispersed throughout the polymer.
  11. A conductive composite according to any of claims 1-10, wherein the conductive composite has a bulk conductivity as measured according to ASTMD257 of no more than about 5 x 10 5 S/m at 20°C, an elongation as measured according to ASTM D1708 greater than or equal to 50 %, and a tensile strength as measured according to ASTM D1708 greater than or equal to 3 MPa.
  12. A conductive composite according to any of claims 1-11, further comprising an additive that increases thermal oxidative stability.
  13. A composition comprising a metal alloy having a melting temperature below 60°C and a compatibilizing agent, wherein the compatibilizing agent comprises a nonionic amphiphilic compound selected from the group consisting of fatty alcohol ethoxylates, alkylphenol ethoxylates, fatty acid ethoxylates, ethoxylated amines, fatty acid amides, polyoxyethylene-polyoxypropylene copolymers, fatty acid esters of polyhydroxy compounds, glycerol fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, alkyl polyglucosides, fatty amine oxides, sulfoxides, organophosphine oxides, and mixtures thereof, wherein the conductor is an alloy comprising at least about 50% by weight of gallium, bismuth, mercury, or combinations thereof wherein the composition preferably further comprises an inorganic thickening agent or an organic thickening agent.
  14. A method for preparing a conductive composite comprising combining a mixture of monomers or a polymer composition with (a) a conductor selected from metal alloys having a melting temperature below about 60°C and (b) a compatibilizing agent or layering a conductive paste onto a surface of a first polymer, wherein the conductive paste comprises (a) a conductor selected from metal alloys having a melting temperature below about 60°C and; and (b) a compatibilizing agent, wherein the compatibilizing agent comprises a nonionic amphiphilic compound selected from the group consisting of fatty alcohol ethoxylates, alkylphenol ethoxylates, fatty acid ethoxylates, ethoxylated amines, fatty acid amides, polyoxyethylene-polyoxypropylene copolymers, fatty acid esters of polyhydroxy compounds, glycerol fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, alkyl polyglucosides, fatty amine oxides, sulfoxides, organophosphine oxides, and mixtures thereof and wherein the conductor is an alloy comprising at least about 50% by weight of gallium, bismuth, mercury, or combinations thereof.
  15. A substrate carrying a layer of the conductive composite according to any of claims 1-12

Description

FIELD This disclosure relates to conductive composite materials, more specifically to conductive polymer composites, and to methods and compositions useful for preparing such materials. BACKGROUND A conductive composite, broadly defined, is any composite having significant electrical or thermal conductivity. Such composites contain an electrically conducting phase dispersed in a polymeric resin. The unique properties of such composites make them technologically superior to or more cost effective than alternative materials in a variety of applications. As a result, conductive composites have a broad range of uses in areas such as telecommunications, power generation and distribution, defense, aerospace, medicine. In the context of using conductive composites, conductivity is not only significant, but is typically a primary characteristic of the composite. The conductivity of the materials varies by use. For certain applications, composites that have an effective sheet resistance of less than 100 Ohm/sq are important. Conductive composites are commonly manufactured by and/or properties are achieved by incorporating a polymeric material with solid conductive particles. To achieve sufficient conductivity, i.e., to reach percolation, high particle loadings, typically in excess of 45 volume %, are often needed. The polymers used with these particle loading levels are normally rigid materials. As a consequence, these particle loading levels result in conductive films and coatings that have properties such as elongation at break, tensile strength, and thermal stability that make them inappropriate or difficult to use. Solutions to this problem that employ liquid metal suffer from leakage of the metal from the polymer matrix. There also exists a need for conductive polymer coatings and films having a wide operating temperature range. Therefore, there is a need for composites that are conductive, avoid leakage of the metal from the polymer, and have characteristics that permit a wide variety of uses under different environmental conditions, i.e., elongation, tensile strength, and thermal stability. WO2019/136252A1 describes a method for synthesizing a thermally conductive and stretchable elastomer composite comprises mixing liquid metal and soft material (e.g., elastomer) in a centrifugal or industrial shear mixer under conditions such that the liquid metal forms microscale liquid metal droplets that are dispersed in the soft elastomer. EP3502155A1 describes conductive composites comprising a polymer, a conductor selected from metals and metal alloys, and a thickening agent. CN108986949A describes an electrically conductive composite material which is composed of in percentage by weight, 30 to 80 % of a conductive substrate, 20 to 40 % of a conductivity adjusting powder, 0 to 5 % of a surfactant, 0 to 5 % of a modifier, 0 to 10 % of a binder and 0 to 5 % of a solvent, wherein the conductive substrate is a low-melting metal with a melting point lower than 300 °C, or the conductive substrate is a mixture of a low-melting metal with a melting point lower than 300 °C and an oxide thereof. CN108447592A describes a liquid metal-based stretchable flexible functional conductor and a preparation method thereof. The method comprises the following steps: (1) a polymer solution and a liquid metal are blended uniformly to obtain a conductive composite material; (2) the conductive composite material is loaded on a flexible carrier to obtain the liquid metal-based stretchable flexible functional conductor. Mrozek R.A. et al., Polymer, vol. 51, no. 14, 2010, pages 2954-2958, describe a polymer composite loaded with a eutectic metal that is molten during melt processing along with a more traditional nickel particulate filler. Yan Jiajun et al., Nature Nanotechnology, vol. 14, no. 7, 2019, pages 684-690, describe the synthesis of EGaln (eutectic gallium indium) nanodroplets stabilized by polymeric ligand encapsulation, using a surface-initiated atom transfer radical polymerization initiator to covalently functionalize the oxide layer on the surface of the EGaln nanodropletsr' with poly(methyl methacrylate) (PMMA), poly(n-butyl acrylate) (PBMA), poly(2-dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(n-butyl acrylate-blockmethyl methacrylate) (PBA-b-PMMA). CN107452436A describes a liquid-state metal electronic paste which comprises an organic carrier and liquid-state metal, wherein the liquid-state metal is dispersed in the organic carrier, the organic carrier comprises an organic solvent, a binding agent and a functional additive, and the liquid-state metal is elemental metal or alloy with a melting point being -78.2 to 232 °C. SUMMARY According to an aspect there is provided a conductive composite according to claim 1. According to another aspect there is provided a composition according to claim 13. According to yet another aspect there is provided a method for preparing a conductive composite according to claim 14. According to