COF Porous Acoustic Material for Loudspeaker Low-Frequency Response

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Solution Overview

Problem

Existing porous materials used in loudspeakers, such as zeolite and activated carbon, have high material density and inconsistent properties, making it difficult to achieve consistent acoustic performance and stability.

Innovation Solution

A porous acoustic volume enhancing material composed of covalent organic frameworks (COFs) with specific properties, including a thermal decomposition temperature of 300°C or higher, density of 0.20 g/cc or more, and a particle specific surface area of 200 m²/g, is used, combined with an adhesive to form granular or blocky materials for the loudspeaker's rear cavity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of stationary object

If traditional porous materials (zeolite, activated carbon) are used as volume enhancing materials, then the virtual volume of the loudspeaker cavity is increased, but the material density is high and acoustic performance consistency is difficult to achieve

Engineering Contradiction:
Improvevirtual volume of loudspeaker cavityVSAvoidacoustic performance consistency
Core Design Contradiction:
Volume of stationary objectVSReliability

Solution Approach 1:

The patent employs porous covalent organic framework (COF) materials with controlled pore structures to enhance the virtual volume of the loudspeaker cavity. The COF materials possess well-defined porous structures with tunable pore sizes and high surface areas, enabling effective acoustic volume enhancement while maintaining low density and consistent acoustic performance through controlled synthesis parameters.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The patent systematically varies synthesis parameters including temperature, pressure, time, and chemical composition to control the pore structure, surface area, and density of COF materials. By optimizing these parameters, the invention achieves consistent acoustic performance and stability while maintaining low material density, resolving the contradiction between volume enhancement and performance consistency.

Inventive Principle:
Principle #35Parameter changes

2Volume of stationary object

If inorganic minerals like zeolite are used, then the virtual volume is enhanced, but the material has high density and limited acoustic performance tuning

Engineering Contradiction:
Improvevirtual volumeVSAvoidmaterial density
Core Design Contradiction:
Volume of stationary objectVSWeight of stationary object

Solution Approach 1:

The patent utilizes covalent organic framework (COF) materials, which are organic composite materials with well-defined structures. These COF materials combine lightweight organic components with porous architectures, achieving low density while providing enhanced virtual volume. The organic nature of COFs allows for chemical tunability and lighter weight compared to traditional inorganic minerals like zeolite.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention employs porous COF materials with controlled pore structures that provide high virtual volume enhancement at low material density. The porous architecture of COFs creates effective acoustic volume without adding significant mass, directly addressing the contradiction between volume enhancement and weight reduction.

Inventive Principle:
Principle #31Porous materials

3Reliability

If porous materials with high surface area are used, then acoustic performance is improved, but manufacturing consistency becomes difficult

Engineering Contradiction:
Improveacoustic performanceVSAvoidproperty consistency
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent establishes controlled synthesis parameters including temperature, pressure, time, and chemical composition to consistently produce COF materials with desired pore structures and surface areas. By systematically optimizing and controlling these parameters, the invention achieves reproducible acoustic performance and property consistency, resolving the manufacturing challenge of high-surface-area porous materials.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The COFs material provides excellent low-frequency sound absorption and shock absorption, with improved acoustic performance and stability due to its lower density and controlled pore structure, outperforming traditional materials.

Implementation Method 1

The operating principle relies on the adsorption effect of porous materials to increase the virtual volume constrained by speaker housing

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 2

The COFs material provides excellent low-frequency sound absorption and shock absorption

Methodology Applied
Scientific EffectAcoustic absorption: Acoustic Absorption

Implementation Method 3

with improved acoustic performance and stability due to its lower density and controlled pore structure

Methodology Applied
Scientific EffectPorosity: Porosity

Data Source

PatentEP4644486A1Porous acoustic volume increasing material and preparation method therefor, loudspeaker, and electronic device
Publication Date: 2025.11.05 SSI NEW MATERIAL (ZHENJIANG) CO LTD
  • EP4644486A1 patent drawingFigure 1~2
  • EP4644486A1 patent drawingFigure 3~4
  • EP4644486A1 patent drawingFigure 5~6

AI summary

The present disclosure provides a porous acoustic volume increasing material and a preparation method therefor, a loudspeaker, and an electronic device. The porous acoustic volume increasing material comprises covalent organic frameworks (COFs), wherein the COFs have a thermal decomposition temperature Td greater than or equal to 300°C, a density greater than or equal to 0.20 g/cc, and a particle specific surface area greater than or equal to 200 m2/g. Acoustic impedance and frequency response analysis tests prove that the porous acoustic volume increasing material comprising the COFs can show excellent low-frequency improvement performance. In particular, the acoustic performance of the porous acoustic volume increasing material comprising the COFs having the specific Td (i.e., Td ≥ 300°C) is more excellent.