# US 12,215,211 B2 · Multi-stage foam sound-absorbing black body material and preparation method thereof

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- Number: US 12,215,211 B2
- Document ID: US12215211B2
- Status: Granted
- Kind: B2
- Application number: 18/115,753
- Filed: 2023-02-28
- Published: 2023-06-29
- Granted: 2025-02-04
- Earliest claimed: 2021-04-14
- Assignees: Zhejiang University
- Applicants: Zhejiang University
- Inventors: Zhen Xu; Xiaoting Liu; Kai Pang; Chao Gao
- Web page: https://patentgrep.com/patent/US12215211B2

## CPC

- C04B 30/00: Compositions for artificial stone, not containing binders
- C08J 9/40: Impregnation
- C08J 9/35: Composite foams, i.e. continuous macromolecular foams containing discontinuous cellular particles or fragments
- C04B 2111/52: Sound-insulating materials
- C08J 2201/038: Use of an inorganic compound to impregnate, bind or coat a foam, e.g. waterglass
- C08J 2205/044: Micropores, i.e. average diameter being between 0,1 micrometer and 0,1 millimeter
- C08J 2361/28: with melamine
- C08J 2375/04: Polyurethanes
- C08J 2379/02: Polyamines
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)

## Abstract

In the present invention, a multi-stage foam sound-absorbing black body material is provided for the first time. A graphene aerogel is introduced into a commercialized polymer foam skeleton by using a solvent plasticizing and foaming technology, so as to embed ultra-thin graphene drums in the foam skeleton. When sound waves enter the foam black body, a large number of graphene drums generate a severe resonance effect, thereby rapidly achieving attenuation of the sound waves, and combined with the friction loss of the porous structure of the polymer foam on the sound waves, excellent sound-absorbing performance is achieved in a wide frequency range. The present solution is provided on the basis of commercialized foam materials, has a simple method, low costs, and the potential of wide industrial application.

## Claims

### Claim 1

A preparation method for a multi-stage foam sound-absorbing black body material, comprising the steps of:
immersing a polymer foam into a graphene oxide dispersion, with graphene oxide of the graphene oxide dispersion filling into an interior of the polymer foam,
drying the polymer foam filled with graphene oxide to obtain a dried foam;
adding the dried foam in a foaming agent solution for foaming, and
drying after foaming to obtain the multi-stage foam sound-absorbing black body material;
wherein the multi-stage foam sound-absorbing black body material comprises a polymer foam skeleton having a pore size of 10 μm or more and a continuous graphene resonant cavity attached thereto, wherein a cavity wall of the graphene resonant cavity is graphene having a thickness of 100 nm or less; and wherein the polymer foam skeleton forms a primary foam structure, and the graphene resonant cavity forms a secondary foam structure.

### Claim 2 (depends on 1)

The preparation method according to claim 1, wherein the graphene oxide is prepared by a Hummers method, an improved Hummers method or an electrochemical method.

### Claim 3 (depends on 1)

The preparation method according to claim 1, wherein the graphene oxide dispersion has a concentration of 0.1-50 mg/g.

### Claim 4 (depends on 1)

The preparation method according to claim 1, wherein the foaming agent solution is one of hydrazine hydrate solution, sodium borohydride solution, sodium bicarbonate solution and sodium carbonate solution.

### Claim 5 (depends on 1)

The preparation method according to claim 1, further comprising chemically or thermally reducing the foam after the foaming.

### Claim 6 (depends on 1)

The preparation method according to claim 1, wherein the multi-stage foam sound-absorbing black body material has an average sound-absorbing coefficient of 0.8 or more at 100-10000 Hz.