Laminated Soundproof Material with Porous and Non-Porous Layers
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Solution Overview
Problem
Conventional soundproof materials struggle to maintain high sound absorption coefficients while being thin and having a wide sound-absorbable frequency range, particularly failing to effectively absorb low-frequency noises.
Innovation Solution
A laminated soundproof material comprising a surface cover layer of fibers with a specific diameter, a porous back-surface layer with interconnected voids, and a joining layer with a predetermined joint area percentage, which enhances sound absorption across a broad frequency range without significant thickness increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of sound absorbing material is increased, then the sound absorption coefficient on the low frequency side is improved, but the material becomes thicker and heavier
Solution Approach 1:
The invention uses a composite structure consisting of a porous layer (foam material or fiber material) and a non-porous layer (resin layer) bonded together. This composite structure allows the thin material to achieve high sound absorption coefficients across a broad frequency range, including low frequencies, without increasing thickness. The porous layer provides sound absorption while the non-porous layer adds mass and modifies the resonance characteristics.
Solution Approach 2:
The invention changes the physical and chemical parameters of the material layers, including the porous degree, density, thickness, and bonding strength of each layer. By optimizing these parameters, the material achieves enhanced sound absorption performance in a thin configuration. Specifically, controlling the porous degree of the porous layer and the bonding strength between layers allows tuning of the resonance frequency and sound absorption characteristics.
2Adaptability or versatility
If the thickness of sound absorbing material is increased, then the sound-absorbable frequency region is expanded, but the material becomes thicker and heavier
Solution Approach 1:
The composite structure of porous and non-porous layers creates multiple sound absorption mechanisms operating simultaneously. The porous layer absorbs sound through viscous friction in its pores, while the non-porous layer and the interface between layers create resonance effects. This combination expands the sound-absorbable frequency region to include both mid-high frequencies (from porous absorption) and low frequencies (from resonance), all within a thin profile.
Solution Approach 2:
Different regions of the material have different properties: the porous layer has high porosity for mid-high frequency absorption, while the non-porous layer has low porosity and higher density for low frequency resonance. This spatial distribution of different material qualities enables broad frequency coverage without increasing overall thickness.
3Reliability
If a laminated structure with adhesion layer is used, then resonance phenomenon is expressed at the interface improving sound absorption, but the balanced control on sound absorption coefficient in low to high frequency regions is still insufficient
Solution Approach 1:
The invention uses a composite structure with a porous layer and a non-porous layer, where the non-porous layer replaces or supplements the traditional adhesion layer. This composite structure provides better balanced control over sound absorption across the full frequency range. The non-porous layer's mass and stiffness properties, combined with the porous layer, create a more effective resonance system that enhances low frequency absorption while maintaining mid-high frequency performance.
Solution Approach 2:
The invention optimizes multiple parameters including the thickness ratio, density ratio, and bonding strength between layers to achieve balanced broadband sound absorption. By controlling the porous degree of the porous layer (50-90%) and its thickness (1-10 mm), along with the non-porous layer properties, the material achieves improved sound absorption coefficients across low, mid, and high frequencies simultaneously.
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 material achieves high sound absorption coefficients across a wide frequency range, effectively absorbing various daily life noises while maintaining thinness, thus providing a practical solution for noise reduction in noisy environments.
Implementation Method 1
The sound absorption mechanism is such that when sound is incident on a material composed of a skeleton part of fiber materials, such as felt, glass wool, and rock wool, and voids therebetween, part of energy of sound waves is converted into heat energy in the voids by friction with peripheral walls of the skeleton part, viscous resistance, vibration of the skeleton and the like, resulting in the sound being absorbed.
Implementation Method 2
part of energy of sound waves is converted into heat energy in the voids by friction with peripheral walls of the skeleton part
Implementation Method 3
viscous resistance, vibration of the skeleton and the like, resulting in the sound being absorbed
Implementation Method 4
by the use of the adhesion layer between the air-permeable resonance layer and sound absorbing layer, a resonance phenomenon is expressed at an interface between the air-permeable ultra-light resonance layer and sound absorbing layer, whereby the sound is absorbed
Data Source
AI summary
An object of the present invention is to provide a soundproof material having a practically useful high-level sound absorption coefficient that while maintaining thinness, and further having an expanded sound-absorbable frequency region. A means for solving the problem is a soundproof material comprising: a surface cover layer composed of a fiber material; a back-surface layer laminated onto the surface cover layer, and composed of a porous material with voids interconnected with each other; and a joining layer laminated between the surface cover layer and the back-surface layer, and composed of a joining material, wherein the fiber material has an average fiber diameter of 1 to 10 μm and an air-permeation volume of 5 to 200 cm3/cm2·sec, and wherein the joining layer has a joint area percentage of 50 to 95% with respect to the entire surface where the surface cover layer and the back-surface layer face each other.