Acoustically active articles

Patent metadata

Field	Value
Publication number	US-2019016643-A1
Application number	US-201616064501-A
Country	US
Kind code	A1
Filing date	Dec 22, 2016
Priority date	Dec 30, 2015
Publication date	Jan 17, 2019
Grant date	—

Abstract

Articles and methods of making and using the articles are provided. The articles include inorganic agglomerates having an average dimension in a range from about 50 microns to about 2 mm. The porous agglomerates each include a network of carbon or silica, and metal oxide particles embedded in the network. Some agglomerates are capable of lowering a resonant frequency of an acoustic device when the resonant frequency is in a range from about 50 Hz to about 1500 Hz.

First claim

1 . An article comprising:
a plurality of porous inorganic agglomerates having an average dimension in a range from about 50 microns to about 2 mm, the porous agglomerates each including a network of carbon or silica, and metal oxide particles embedded in the network.

2 . The article of claim 1 , wherein the network of carbon or silica is a pyrolysis product of a polymer binder at an elevated temperature in a range from 400 to 1000° C.

3 . The article of claim 2 , wherein the polymer binder includes one or more of vinyl, (poly)styrene, (poly)acrylonitrile, (poly)acrylate, phenolic, benzoxazine, melamine resin, epoxy, and silicone.

4 . The article of claim 1 , wherein the metal oxide particles include aluminum oxide or hydroxide.

5 . The article of claim 1 , wherein the metal oxide particles include one or more of zirconium oxide, zirconium hydroxide, ferrous hydrate, or compound transition metal oxide.

6 . The article of claim 1 comprising about 5 to about 25 wt % carbon or silica, and about 95 to about 75 wt % metal oxide particles.

7 . The article of claim 1 , wherein the porous agglomerates have a packing density in a range from 0.05 to 1.0 g/cc.

8 . The article of claim 1 , wherein the metal oxide particles have an average dimension in a range from about 100 nm to about 20 microns.

9 . The article of claim 1 , comprising no substantial amount of zeolite.

10 . The article of claim 1 , wherein the porous inorganic agglomerates are electrically insulative.

11 . The article of claim 1 , wherein the porous inorganic agglomerates are hydrophobic.

12 . An acoustic device comprising a transducer in the presence of a cavity, and the article of claim 1 , the article being received by the cavity, wherein the porous inorganic agglomerates are capable of lowering a resonant frequency of the acoustic device when the resonant frequency is in a range from about 50 Hz to about 1500 Hz, and the porous inorganic agglomerates have an effective bulk modulus less than the bulk modulus of air or less than about 100,000 Pa.

13 . The acoustic device of claim 12 , wherein the porous inorganic agglomerates are present in the form of a film, a foam, or a fiber mat.

14 . The acoustic device of claim 12 , which is a speaker.

15 . A method of forming an article including porous inorganic agglomerates, the method comprising:
providing metal oxide powders having an average particle size in a range from 100 nm to 10 microns; mixing the metal oxide powders with one or more reactive monomers or polymers containing carbon or silicon and water to form a mixture; polymerizing the mixture to form a plurality of composite beads, the composite beads each comprising the metal oxide powders distributed inside a polymeric binder, and the composite beads having an average size in a range from about 50 microns to about 2 mm; and heating the composite beads at an elevated temperature in a range from about 400 to about 1000° C. to form the porous inorganic agglomerates.

16 . The method of claim 15 , wherein the reactive monomers or polymers comprise (i) one or more of styrene and derivatives, vinyl ester monomer(s), acrylate monomer(s), methyl acrylate(s), acrylonitrile, and multi carbon double-bond monomer(s), and (ii) one or more of monomer(s) that are polymerizable to form a polymer with a high char yield in nitrogen gas, and semi-aromatic or aromatic polymers or oligomers with a high char yield in nitrogen gas.

17 . The method of claim 15 , wherein mixing the metal oxide powders further comprises mixing the metal oxide into an oil phase, wherein the oil phase comprises a mixture of (i) 5 to 30 wt % of metal oxide powders, (ii) sufficient amount of a free radical initiator, and (iii) 5 to 95 wt % of the reactive monomers or polymers containing carbon or silicon.

18 . The method of claim 17 , wherein mixing the metal oxide powders further comprises mixing the oil phase with a water phase, wherein the water phase comprises water, the ratio of the water phase to the oil phase is between 10:1 to 1:1 by weight.

19 . The method of claim 15 , further comprising treating the metal oxide powders with a surface treatment agent before mixing the metal oxide powders.

20 . The method of claim 19 , wherein the surface treatment agent comprises silane or fluorine functional groups.

21 - 22 . (canceled)

Assignees

• 3M Innovative Properties Co

Inventors

• Stolzenburg Fabian
• Lin Qin
• Shanti Noah O
• Radcliffe Marc D
• Gerdes Ronald W

Classifications

• C04B2235/3244

  Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof · CPC title

• C04B38/0022 Primary

  obtained by a chemical conversion or reaction other than those relating to the setting or hardening of cement-like material or to the formation of a sol or a gel, e.g. by carbonising or pyrolysing preformed cellular materials based on polymers, organo-metallic or organo-silicon precursors · CPC title

• C04B2235/5445

  submicron sized, i.e. from 0,1 to 1 micron · CPC title

• C04B35/63424

  Polyacrylates; Polymethacrylates · CPC title

• H04R1/2811

  for loudspeaker transducers · CPC title