Acoustic article

Abstract

An acoustic article is provided that includes a first porous layer having a first density and a second porous layer having a second density disposed on the first porous layer. The first density is 110% to 1200% of the second density, or the second density is 110% to 1200% of the first density. The first porous layer includes a plurality of pores extending through the first porous layer, wherein the plurality of pores are not considered when determining the density. These acoustic articles may provide significant noise abatement in a variety of applications, including server enclosures.

Description

Technical Field

[0001] Articles and methods for absorbing acoustic energy are provided. Such articles and methods can be used, for example, in electronic applications. Background Art

[0002] Computer networks have become an indispensable part of people's lives. Many enterprises own their own network servers for storing large amounts of research and development data, financial data, emails, etc. Enterprise-level servers can be used for hundreds of computers connected to the network. Large network servers generate a large amount of noise during operation, especially cooling fans, as they generate noise when operating at high RPM levels.

[0003] The negative impacts of environmental noise on mental and physical health are well documented. Noise problems are not only undesirable from a health perspective, but they also affect the operation of electronic devices. As server hard disk drives have evolved to higher data density levels, they have become more sensitive to interference from fan noise. Noise problems can occur within each server unit, and it is necessary to reduce the noise level between the fan and the hard disk drive. Ultimately, if not attenuated, fan noise may cause degradation of hard disk drive performance. Summary of the Invention

[0004] Technically, there is a need to provide an acoustic absorption panel that includes materials capable of absorbing sound associated with an electronic device and a cooling fan for cooling the device. There is also a need to provide an acoustic absorption panel that meets the requirements of a panel for use with a computer, server, or server rack, such as acoustic absorption frequency, sound attenuation, stiffness, weight, thickness, air flow, and fire resistance.

[0005] Multilayer articles composed of foam layers having different densities are provided herein, where some layers contain macroscopic air gaps while some do not. The multilayer article can be composed of one or more continuous foam layers and one or more discontinuous foam layers. Sound absorption is enhanced when sound has to pass through materials of different densities and when there are air gaps (such as those provided by holes extending through the layers). Optionally, the layer containing holes can be disposed on the surface (i.e., the wall) of the noise generating device using a suitable adhesive. As an additional option, the continuous foam layer without holes has a greater density than the discontinuous foam layer containing holes. Advantageously, these articles exhibit sound attenuation attributable to both density effects and air gap effects. The acoustic article can be enhanced by replicating these layer configurations to further enhance sound absorption.

[0006] In a first aspect, an acoustic article is provided. The acoustic article includes: a first porous layer having a first density; and a second porous layer having a second density disposed on the first porous layer, wherein the first density is 110% to 1200% of the second density, or the second density is 110% to 1200% of the first density, and wherein the first porous layer includes a plurality of holes extending through the first porous layer, and wherein the plurality of holes are not considered when determining the density.

[0007] In a second aspect, an acoustic absorption assembly is provided. The acoustic absorption assembly includes: a substrate; and an acoustic article extending across the substrate, wherein the first porous layer is exposed along a main surface of the acoustic absorption assembly.

[0008] In a third aspect, a method for reducing noise in a housing in which an air flow is present is provided. The method includes: providing an acoustic article including: a first porous layer having a first density; and a second porous layer having a second density disposed on the first porous layer, wherein the first density is 110% to 1200% of the second density, or the second density is 110% to 1200% of the first density, wherein the first porous layer includes a plurality of holes extending through the first porous layer, and wherein the plurality of holes are not considered when determining the density; and disposing the acoustic article within the housing such that the air flow is directed along an exposed main surface of the acoustic article. Description of the Drawings

[0009] Figures 1 to 4 is an exploded perspective view of an acoustic article according to various exemplary embodiments.

[0010] Figure 5 and Figure 6 shows acoustic insertion loss test results of an exemplary acoustic article relative to an acoustic article of a comparative example.

[0011] Figure 7A and Figure 7B are a top view and a side view of a sound horn for testing the insertion loss of an exemplary acoustic article.

[0012] Reference symbols reused in the specification and the drawings are intended to represent the same or similar feature structures or elements of the present disclosure. It should be understood that those skilled in the art can design many other modifications and embodiments that fall within the scope and spirit of the principles of the present disclosure. The drawings may not be drawn to scale.

[0013] Definition

[0014] "Ambient temperature" means at 21 degrees. Detailed Description

[0015] As used herein, the terms "preferred" and "preferably" refer to the embodiments described herein that may provide certain benefits in certain circumstances. However, in the same or other circumstances, other embodiments may also be preferred. In addition, the recitation of one or more preferred embodiments does not imply that other embodiments are not available and is not intended to exclude other embodiments from the scope of the invention.

[0016] As used herein and in the appended claims, unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" include plural referents. Thus, for example, reference to "a" or "the" component can include one or more components known to those skilled in the art or their equivalents. Additionally, the term "and / or" means any one or all of the listed elements or any combination of any two or more of the listed elements.

[0017] It is noted that the term "comprising" and variations thereof do not have a limiting meaning when they appear in the appended specification. Additionally, "a", "an", "the", "at least one", and "one or more" may be used interchangeably herein. Relative terms such as left, right, forward, backward, top, bottom, side, upper, lower, horizontal, vertical, etc. may be used herein, and if so, they are from the perspective observed in the specific figures. However, these terms are only used to simplify the description and do not limit the scope of the invention in any way.

[0018] References throughout this specification to "one embodiment", "certain embodiments", "one or more embodiments", or "an embodiment" mean that a particular feature, structure, material, or characteristic described with respect to the embodiment is included in at least one embodiment of the invention. Thus, the appearances of phrases such as "in one or more embodiments", "in certain embodiments", "in one embodiment", or "in an embodiment" throughout this specification are not necessarily referring to the same embodiment of the invention.

[0019] An acoustic article according to an exemplary embodiment is Figure 1 illustrated in and is referred to herein by the numeral 100. The acoustic article 100 has a bilayer construction and includes a first layer 102 and a second layer 104. Both the first layer 102 and the second layer 104 are porous layers. In some embodiments, the bilayer construction may be reversed, with the second layer placed on top of the first layer.

[0020] The first layer 102 has a main surface 106 that is exposed along the top surface of the acoustic article 100. A plurality of holes 108 extend through the first layer 102 in a direction perpendicular to the main surface 106. Optionally and as shown, the plurality of holes 108 are arranged according to a two-dimensional pattern that repeats on the main surface 106. A grid pattern is shown, but other hole configurations (e.g., hexagonal, semi-random) are also possible. In contrast to the first layer 102, the second layer 104 does not include any holes. In some embodiments, the plurality of holes 108 extend through the second layer 104 in a direction perpendicular to the main surface 106.

[0021] The first layer 102 and the second layer 104 can be made of porous materials having significantly different densities from each other. In some embodiments, the first layer 102 has a first density and the second layer 104 has a second density, where the first density is significantly greater than the second density. In other embodiments, the first layer 102 can have a first density and the second layer 104 can have a second density, where the second density is significantly greater than the first density. For the purposes of this disclosure, the plurality of holes 108 are considered to be macroscopic features that are separate from the body of the first layer 102 and are therefore not considered when determining density.

[0022] More specifically, the first density can be 110% to 1200%, 115% to 400%, 120% to 200%, or in some embodiments less than, equal to, or greater than 110%, 115%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, 200%, 250%, 300%, 350%, 400%, 450%, 500%, 600%, 700%, 800%, 900%, 1000%, 1100%, or 1200% of the second density. The first density itself can be 16 kg / m 3 to 400 kg / m 3 、48 kg / m 3 to 160 kg / m 3 、80 kg / m 3 to 130 kg / m 3 ,or in some embodiments less than, equal to, or greater than 16 kg / m 3 、20 kg / m 3 、30 kg / m 3 、48 kg / m 3 、50 kg / m 3 、60 kg / m 3 、70 kg / m 3 、80 kg / m 3 、90 kg / m 3 、100 kg / m 3 、130 kg / m 3 、160 kg / m3 , 200 kg / m 3 , 300 kg / m 3 or 400 kg / m 3 . Similarly, the second density may be 16 kg / m 3 to 400 kg / m 3 , 48 kg / m 3 to 160 kg / m 3 , 80 kg / m 3 to 130 kg / m 3 , or in some embodiments less than, equal to, or greater than 16 kg / m 3 , 20 kg / m 3 , 30 kg / m 3 , 48 kg / m 3 , 50 kg / m 3 , 60 kg / m 3 , 70 kg / m 3 , 80 kg / m 3 , 90 kg / m 3 , 100 kg / m 3 , 130 kg / m 3 , 160 kg / m 3 , 200 kg / m 3 , 300 kg / m 3 or 400 kg / m 3 .

[0023] The porous layers described herein are composed of materials containing a plurality of embedded pores or voids. In some cases, the pores are interconnected, in which case the material is considered to be open-cell. In other cases, the pores are not connected to each other, in which case the material is considered to be closed-cell. The material of the porous layer may also fall within the continuum between these two cases, where some but not all of the pores are connected to the pores around them. For clarity, in the present disclosure, the pores within the first layer 102 and the second layer 104 are considered when determining the density of these layers.

[0024] The first porous layer 102 and the second porous layer 104 can have any suitable porosity. In some embodiments, the first porous layer has a first porosity, the second porous layer has a second porosity, and the first porosity is significantly different from the second porosity. In some cases, the second porosity can be 5% to 90%, 10% to 80%, 20% to 60%, or in some embodiments, less than, equal to, or greater than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90% of the first porosity. Conversely, the first porosity can be 5% to 90%, 10% to 80%, 20% to 60%, or in some embodiments, less than, equal to, or greater than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90% of the second porosity.

[0025] The first porosity can be 30% to 99.9%, 65% to 98%, 85% to 96%, or in some embodiments, less than, equal to, or greater than 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.2%, 99.5%, 99.7%, 99.8%, or 99.9%. The second porosity can be 30% to 99.9%, 65% to 98%, 85% to 96%, or in some embodiments, less than, equal to, or greater than 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.2%, 99.5%, 99.7%, 99.8%, or 99.9%. In each of the above cases, the plurality of pores 180 are not considered when determining the porosity.

[0026] The porous layers 102, 104 can be made of any suitable material. Suitable materials can include polymers, metals, ceramics, and combinations thereof. In some embodiments, both of the porous layers 102, 104 are made of polymer foams. Each polymer foam is, for example, a polyurethane foam that has viscoelasticity at ambient temperature. This viscoelasticity can be manifested by a peak tanδ (peak loss tangent value) of at least 1.0, which is measured by dynamic mechanical analysis in the range of 1 hertz to 10,000 hertz and -20 degrees Celsius to 70 degrees Celsius, with an amplitude of 0.3% at 30% pre-compression.

[0027] The first layer 102 and the second layer 104 can be welded to each other by thermal welding, ultrasonic welding, or chemical welding, bonded to each other in an adhesive manner, or otherwise fixed to each other by mechanical means. Suitable adhesives can include curable adhesives, thermally fusible adhesives, and pressure-sensitive adhesives. If an adhesive is used, the adhesive can continuously extend over the entire major surface of the second layer 104 facing the first layer 102, or alternatively, the adhesive can only extend along the bottom-facing surface of the first layer 102 such that no adhesive is provided on the holes 108. In some cases, this latter configuration can confer acoustic benefits by allowing air to permeate into the exposed holes of the second porous layer 104.

[0028] It should also be understood that although the first layer 102 is considered the top layer and the second layer 104 is considered the bottom layer as described herein, the acoustic article 100 can have any suitable orientation based on the desired installation and the direction of incoming sound energy. Additionally, one or both of the first layer 102 and the second layer 104 can be replicated in an alternating pattern (e.g., ABA, ABAB, BAB, or ABABA) to enhance the layer structure of the acoustic article 100 and provide a configuration having 3, 4, 5, 6, or any other suitable number of layers. Such enhancement can further enhance the sound absorption ability of the acoustic article 100.

[0029] The layers of the acoustic article 100, such as the first layer 102 or the second layer 104, are not particularly limited and can have any suitable thickness. The thickness can be from 0.1 millimeters to 120 millimeters, from 1 millimeter to 60 millimeters, from 2 millimeters to 20 millimeters, or in some embodiments less than, equal to, or greater than 0.1 millimeters, 0.2 millimeters, 0.3 millimeters, 0.4 millimeters, 0.5 millimeters, 1 millimeter, 2 millimeters, 5 millimeters, 10 millimeters, 15 millimeters, 20 millimeters, 25 millimeters, 30 millimeters, 35 millimeters, 40 millimeters, 45 millimeters, 50 millimeters, 60 millimeters, 70 millimeters, 80 millimeters, 90 millimeters, 100 millimeters, 110 millimeters, or 120 millimeters.

[0030] Figure 2 An acoustic article 200 having a first layer 202 and a second layer 204 similar to the previous embodiments is shown. Different from the previous embodiments, both the first layer 202 and the second layer 204 have holes extending therethrough. As depicted, the first layer 202 includes a plurality of first holes 208, 208', 208'', while the second layer 204 includes a plurality of second holes 210. Optionally and as shown, the holes 208, 208', 208'' have different sizes, while the holes 210 are substantially uniform in their sizes and shapes. As previously explained, the first layer 202 and the second layer 204 are preferably porous layers and can have significantly different degrees of density and / or porosity, depending on the application at hand.

[0031] Helmholtz resonators can be set using holes 208, 208', 208” of different sizes. The Helmholtz resonator is a resonant chamber tuned to operate at a specific sound frequency. The size of the holes can be appropriately adjusted according to the multiple frequencies of the acoustic energy for the application.

[0032] When shown in a plan view, the holes in the first layer 202 and the holes in the second layer 204 may or may not overlap with each other. For example, in Figure 2 the central hole 208” in the first layer 202 is aligned with the hole in the second layer 204, while many other holes 208, 208' are not aligned.

[0033] Additional options and related advantages associated with the first layer 202 and the second layer 204 have been previously described and need not be repeated here.

[0034] Figure 3 An acoustic article 300 according to another embodiment is shown. The acoustic article includes a first layer 302, a second layer 304, and a third layer 305. The first layer 302 and the second layer 304 are substantially similar to those in the previous embodiments. The third layer 305 may be composed of a porous layer having a density and / or porosity significantly different from either the first layer 302 or the second layer 304. Different from the first layer 302 and the second layer 304, the third layer 305 does not include any holes. As previously explained, enhancement of the acoustic article 300 is also possible by replicating one or more of the layers 302, 304, 305.

[0035] Figure 4 Yet another acoustic article 400 is provided. The acoustic article includes a first layer 402, a second layer 404, and a third layer 405 in a sandwich configuration. The second layer 404 has a plurality of holes 408 extending therethrough. The first layer 402 and the third layer 405 have similar densities (or porosities), while the second layer has a density (or porosity) significantly greater than or less than that of the first layer 402 and the third layer 405. Alternatively, the first layer 402, the second layer 404, and the third layer 405 all have different densities (or porosities).

[0036] The acoustic article described herein can be coupled to any of a variety of suitable substrates to attenuate noise. In one exemplary application, the substrate comprises the housing of a computer server. The coupling to the substrate can be achieved by bonding the primary surface of the acoustic article to the surface of the substrate. The acoustic article can also be suspended from the substrate along one or more of its peripheral edges, thereby exposing one or both of its primary surfaces. In such a suspended configuration, there can be two or more acoustic articles arranged adjacent to each other, with an air gap extending therebetween. In some cases, the substrate can be a housing, where the acoustic article is suspended from one or more walls of the housing. In each of the above cases, the acoustic article can be mounted or secured relative to the substrate in a manner that directs airflow along the exposed primary surface of the acoustic article.

[0037] Example

[0038] Unless otherwise specified or readily apparent from the context, all amounts, percentages, ratios, etc. in the examples and the remainder of the specification are by weight. Where applicable, brand names and trade names are shown in all capital letters.

[0039] Table 1: Materials

[0040]

[0041] Test method

[0042] Insertion loss test

[0043] As Figure 7A and Figure 7BAs shown, an acrylonitrile-butadiene-styrene (ABS) acoustic horn (with an inlet diameter of 10 cm (9.94 inches) and an outlet cross-section of 66.4 cm × 6.5 cm (26.14 inches × 2.56 inches)) was used to measure the effect of the sample on sound propagation. Three calibrated type 4190 free-field microphones (Hottinger Brüel&Kjaer of Nearum, Denmark) were placed approximately 20 cm apart from each other and from the outlet of the acoustic horn, with one microphone positioned at the center of the horn and the other two placed on either side of the central microphone in the same plane. Microphone data was collected and analyzed using a data acquisition system and the associated PULSE Labshop software from Hottinger Brüel&Kjaer. Full-spectrum white noise (total sound pressure level 82.547 dB(A)) was emitted from a Hottinger Brüel&Kjaer type 4206 impedance sound source loudspeaker in the range of 20 Hz to 20,000 Hz. The sample was placed in the acoustic horn without additional fixation. The difference between the average sound pressure level (SPL) measured from the three microphones when no sample was placed in the acoustic horn and the average sound pressure level measured from the three microphones when the sample was placed in the acoustic horn is the insertion loss.

[0044] Examples 1 to 16 (EX1-EX16) and Comparative Examples 1 to 2 (CE1-CE2)

[0045] Assemble the samples as shown in Table 2. For each sample, the length of each porous layer is 50 cm (19.69 inches), and the width is 7.5 cm (2.95 inches). Square cavities / holes of various sizes (1 cm × 1 cm or 2.2 cm × 2.2 cm) were patterned in the porous layer by die-cutting techniques known to those skilled in the art. The 1 cm × 1 cm holes were patterned as a 3×10 grid in the porous layer. The 2.2 cm × 2.2 cm holes were patterned as a 2×7 grid in the porous layer. The samples were tested with the holes oriented either up or down in the test device. The orientations are shown in Table 2.

[0046] Table 2: Sample structure

[0047]

[0048]

[0049] Insertion loss tests were conducted, and the results are shown in Table 3A (for CE1 and EX1 to EX8) and Table 3B (for CE2 and EX9 to EX16). CE1 and EX1 are visually represented in Figure 5 and CE2 and EX9 are visually represented in Figure 6 ​

[0050] Table 3A: Insertion loss test results

[0051]

[0052]

[0053] Table 3B: Insertion loss test results

[0054]

[0055]

[0056] All references, patents, and patent applications cited in the above applications that have obtained patent certificates are incorporated herein by reference in their entirety in a consistent manner. In the event of any inconsistencies or contradictions between the incorporated reference section and this application, the information in the foregoing description shall prevail. The foregoing description provided to enable a person of ordinary skill in the art to practice the present disclosure protected by the claims should not be construed as a limitation on the scope of the present disclosure, which is defined by the claims and all their equivalents.

Claims

1. An acoustic article, the acoustic article comprising: A first porous layer having a first density; and a second porous layer having a second density, the second porous layer being disposed on the first porous layer, wherein the first density is 110% to 1200% of the second density, or the second density is 110% to 1200% of the first density, and wherein the first porous layer includes a plurality of holes extending through the first porous layer, and wherein the plurality of holes are not considered when determining the density.

2. The acoustic article according to claim 1, wherein the first density is 16 kg / m 3 to 400 kg / m 3 .

3. The acoustic article according to claim 2, wherein the second density is 16 kg / m 3 to 400 kg / m 3 .

4. The acoustic article according to any one of claims 1 to 3, wherein the first porous layer has a first porosity, the second porous layer has a second porosity, and the first porosity is 5% to 90% of the second porosity, wherein the plurality of holes are not considered when determining the porosity.

5. The acoustic article according to any one of claims 1 to 4, wherein the first porous layer and / or the second porous layer has a thickness of 0.1 mm to 120 mm.

6. The acoustic article according to any one of claims 1 to 5, wherein the second porous layer is a layer that does not include any holes.

7. The acoustic article according to any one of claims 1 to 6, wherein the plurality of holes are arranged according to a repeating two-dimensional pattern.

8. The acoustic article according to any one of claims 1 to 7, wherein the first porous layer and the second porous layer are bonded to each other.

9. The acoustic article according to any one of claims 1 to 8, wherein the first porous layer, the second porous layer, or both include polymer foam.

10. The acoustic article according to claim 9, wherein the polymer foam includes polyurethane.

11. The acoustic article according to claim 9 or 10, wherein the polymer foam has a peak tanδ of at least 1.0, the peak tanδ being measured by dynamic mechanical analysis in the range of 1 Hz to 10,000 Hz and - 20 degrees Celsius to 70 degrees Celsius, wherein the amplitude is 0.3% at 30% pre-compression.

12. An acoustic absorption assembly, the acoustic absorption assembly comprising: A substrate; and an acoustic article according to any one of claims 1 to 11, the acoustic article extending across the substrate, wherein the first porous layer is exposed along a main surface of the sound absorbing assembly.

13. The sound-absorbing component according to claim 12, wherein the acoustic article is bonded to the substrate.

14. The sound-absorbing component according to claim 12, wherein the acoustic article is fixed adjacent to the substrate with a gap therebetween.

15. The sound-absorbing component according to any one of claims 12 to 14, wherein the substrate comprises a server housing.

16. A method of reducing noise in a housing in which there is an air flow, the method comprising: Provided is an acoustic article, the acoustic article comprising: a first porous layer having a first density; and a second porous layer having a second density, the second porous layer being disposed on the first porous layer, wherein the first density is 110% to 1200% of the second density, or the second density is 110% to 1200% of the first density, wherein the first porous layer includes a plurality of holes extending through the first porous layer, and wherein the plurality of holes are not considered when determining the density; and disposing the acoustic article within the housing such that the airflow is directed along an exposed main surface of the acoustic article.

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