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CN-121999746-A - Acoustic articles and related methods

CN121999746ACN 121999746 ACN121999746 ACN 121999746ACN-121999746-A

Abstract

The present application provides acoustic articles and related methods. Specifically, the present application provides an acoustic article having a porous layer (102, 104, 106) placed in contact with a heterogeneous filler comprising porous carbon and having an average surface area of from 0.1m 2 /g to 10,000m 2 /g. The acoustic article can have a flow resistance of 10MKS Rayls to 5000MKS Rayls. Optionally, the porous layer comprises a nonwoven fibrous layer or a perforated film having a plurality of openings having an average narrowest diameter of 30 microns to 5000 microns. The heterogeneous filler can enhance low frequency properties without significantly compromising high frequency properties, thickness, or weight.

Inventors

  • LI CHENGKUI
  • Mei Gan.a.kelaidun
  • JONATHAN H. ALEXANDER
  • MICHAEL R. BERRIGAN
  • THOMAS P. HANSHEN

Assignees

  • 3M创新有限公司

Dates

Publication Date
20260508
Application Date
20181019
Priority Date
20171019

Claims (12)

  1. 1. An acoustic article, the acoustic article comprising: A porous layer comprising a nonwoven fibrous layer having a plurality of fibers, and A heterogeneous filler in contact with the porous layer, the heterogeneous filler comprising porous carbon and having an average surface area of from 0.1m 2 /g to 10,000m 2 /g, wherein the heterogeneous filler is dispersed and physically and/or adhesively held in the fibers of the nonwoven fibrous layer, and Wherein the acoustic article has a flow resistance of 100MKS Rayls to 5000MKS Rayls.
  2. 2. The acoustic article of claim 1 further comprising a second porous layer comprising a perforated membrane having a plurality of openings having an average narrowest diameter of 30 microns to 5000 microns.
  3. 3. The acoustic article of claim 2 wherein the perforated film alone has a flow resistance of 10MKS Rayls to 3000MKS Rayls.
  4. 4. The acoustic article of claim 2 or 3 wherein at least some of the heterogeneous filler resides within the plurality of openings.
  5. 5. The acoustic article of claim 1 or 2, wherein the heterogeneous filler is present in an amount of 10 wt% to 95 wt% relative to the total weight of the porous layer and heterogeneous filler contacting the porous layer.
  6. 6. The acoustic article of claim 1 or 2, further comprising a barrier layer extending across a major surface of the porous layer, the barrier layer having a flow resistance of 10MKS Rayls to 5000MKS Rayls.
  7. 7. The acoustic article of claim 1 or 2, wherein the porous carbon comprises activated carbon, vermicular carbon, or a mixture thereof.
  8. 8. The acoustic article of claim 1 or 2, wherein the heterogeneous filler is a blended filler comprising: A first heterogeneous filler having an average surface area of at most 1300m 2 /g, and A second heterogeneous filler, the second heterogeneous filler having an average surface area of at least 1300m 2 /g.
  9. 9. A method of making an acoustic article, the method comprising: Disposing a heterogeneous filler comprising porous carbon into a porous layer, the porous layer comprising a nonwoven fibrous layer having a plurality of fibers, the heterogeneous filler having an average surface area of 0.1m 2 /g to 10,000m 2 /g to increase sound absorption of the acoustic article at sound frequencies of 50Hz to 2,000Hz, wherein the heterogeneous filler is dispersed and physically and/or adhesively retained in the fibers of the nonwoven fibrous layer.
  10. 10. An acoustic assembly comprising the acoustic article of any of claims 1-8 and further comprising a primary aviation or automotive structure coupled to the acoustic article.
  11. 11. A method of using the acoustic article of any of claims 1-8, the method comprising: the acoustic article is positioned proximate to a surface to dampen vibrations of the surface.
  12. 12. A method of using the acoustic article of any of claims 1-8, the method comprising: The acoustic article is positioned proximate to an air cavity to absorb acoustic energy transmitted through the air cavity.

Description

Acoustic articles and related methods The present application is a divisional application of PCT international application No. PCT/US2018/056671, national application No. 201880066461.5 and application entitled "acoustic article and related method" on day 19 of 10 of 2018. Technical Field Acoustic articles suitable for use in thermal and acoustic insulation are described herein. The provided acoustic articles may be particularly useful for reducing noise in automotive and aerospace applications. Background Historically, advances in automotive and aerospace technology have been driven by consumer demand for faster, safer, quieter, and more spacious vehicles. These attributes must be balanced against the need for fuel economy, as enhancement of these consumer driven attributes generally also increases the weight of the vehicle. With a 10% reduction in vehicle weight that can provide an increase in fuel efficiency of about 8%, motor vehicle and aerospace manufacturers have significant power to reduce vehicle weight while meeting existing performance objectives. However, as the vehicle structure becomes lighter, noise may become more and more problematic. Some of the noise is carried by structural vibrations, which generate acoustic energy that propagates and is transmitted to the air, thereby generating airborne noise. Damping materials made of heavy viscous materials are conventionally used to control structural vibrations. Soft, pliable materials (such as fibers or foam) capable of absorbing acoustic energy are conventionally used to control airborne noise. Structural and airborne noise can be reduced by a technique known as near-field damping. The near field region is defined as the region near the surface of the vibrating structure where air flows laterally back and forth along the panel. The near field region may be modified using an acoustic absorber in which acoustic energy is dissipated through viscous interactions of the fluid and the fibers. Such dissipation can significantly reduce noise, vibration, and harshness experienced by vehicle occupants. Disclosure of Invention Known airborne sound absorbers may perform well at high sound frequencies, but generally perform poorly at low sound frequencies (< 800 Hz). Conventionally, this technical problem has been solved by increasing the thickness of the absorber or adding a heavy barrier layer. However, each of these options can significantly increase the overall weight and thickness of the absorbent body. An alternative solution is described herein that involves disposing high porosity acoustic particles into one or more engineered porous layers to obtain a thin and lightweight acoustic article capable of achieving significant sound absorption at both high and low frequencies. The porous carbon-based acoustic particles can have a large surface area per unit weight. In addition to its large surface area, activated carbon transiently adsorbs gas molecules onto and desorbs gas molecules from its surface. Without being bound by theory, it is believed that the adsorption and desorption properties of the activated carbon change the dynamic bulk modulus of the air to reduce the velocity of sound through the acoustic medium. These properties result in very good low frequency sound absorption properties. For example, 50% normal incidence sound absorption can be achieved with a certain size and amount of activated carbon at 200 Hz. The reduction of the sound velocity has the effect of shortening the acoustic wavelength. Thus, if a suitable amount of acoustic particles of a suitable size is used in combination with the sound absorbing material, a relatively thin layer of the absorbing material may be used to achieve low frequency sound absorption (below 600 Hz). Various types of porous layers may benefit from the addition of these acoustic particles. One type is based on a nonwoven fibrous layer that, at sufficient density, can provide broadband absorption by dissipating acoustic energy along the surface of the fiber. Another type of porous layer is based on a membrane with a plurality of small openings or perforations. The perforated membranes dissipate acoustic energy through friction between the perforated walls and the plugs of air vibrating within them. Porous layers based on open-cell foam and a bed of particles are also possible. These materials benefit from the inclusion of high surface energy particles, which unexpectedly can enhance low frequency performance without significantly compromising high frequency performance, thickness, or weight. In a first aspect, an acoustic article is provided. The acoustic article includes a porous layer, and a heterogeneous filler in contact with the porous layer, the heterogeneous filler comprising porous carbon and having an average surface area of 0.1m 2/g to 10,000m 2/g, wherein the acoustic article has a flow resistance of 100MKS Rayls to 5000MKS Rayls. Optionally, the porous layer comprises a nonwoven fibrous layer h