PTFE Porous Membrane Waterproofing Sound Transmission
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Solution Overview
Problem
Existing waterproof sound-transmitting membranes face challenges in achieving high waterproofness without compromising sound transmittance, particularly when exposed to high water pressure or foreign matter, due to trade-offs between surface density and tensile/puncture strength.
Innovation Solution
A PTFE porous membrane with multiple layers, each with a high molecular weight and small average pore diameter, is developed, where at least one layer has an average pore diameter of 1 µm or less, and a surface density of 1 g/m² to 10 g/m², achieving high tensile and puncture strength while maintaining low surface density through specific stretching and sintering processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the average pore diameter of the PTFE porous membrane is reduced to enhance waterproofness, then the waterproofness is improved, but the surface density of the membrane is increased and the sound transmittance is lowered
Solution Approach 1:
The patent applies parameter changes by precisely controlling the average pore diameter (0.1 µm to 1 µm) and surface density (1 g/m² to 10 g/m²) of the PTFE porous membrane. By optimizing these parameters within specific ranges, the membrane achieves both high waterproofness and maintained sound transmittance, resolving the trade-off between these two properties
Solution Approach 2:
The patent uses composite materials by combining PTFE porous membrane with a backing material (such as polyester, polypropylene, or polyethylene terephthalate). This composite structure allows the PTFE layer to provide waterproofness while the backing material provides mechanical strength and maintains sound transmittance, effectively resolving the contradiction between waterproofness and sound transmission
2Strength
If the surface density of the membrane is increased to enhance tensile strength and puncture strength, then the waterproofness under pressure is improved, but the sound transmittance is lowered
Solution Approach 1:
The patent employs composite materials by combining a PTFE porous membrane with a backing material. The PTFE layer provides waterproofness with low surface density (1-10 g/m²), while the backing material (polyester, polypropylene, or polyethylene terephthalate) provides the necessary mechanical strength and puncture resistance. This composite structure enables the membrane to achieve both high strength and maintained sound transmittance
Solution Approach 2:
The patent applies parameter changes by optimizing the surface density of the PTFE porous membrane to a specific range (1 g/m² to 10 g/m²). This controlled parameter range allows the membrane to maintain low surface density for good sound transmittance while the composite structure with backing material provides the necessary strength for water pressure resistance
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 membrane achieves both high waterproofness and sound transmittance by enhancing tensile and puncture strength while keeping surface density low, allowing for effective water resistance and sound transmission even under pressure and foreign matter exposure.
Implementation Method 1
a water-proof sound-transmitting membrane is known as a member for preventing water from entering into the housing through the openings provided for the sound emitting part and the sound receiving part while ensuring a satisfactory sound transmittance
Implementation Method 2
when a high water pressure is applied to the water-proof sound-transmitting membrane for a certain period of time or longer because the water-proof sound-transmitting membrane is immersed in water, the water pressure stretches the membrane. As a result, micropores of the membrane are deformed
Implementation Method 3
the obtained complex body is subject to heat setting, if needed, to obtain a high-efficiency air filter
Data Source
Figure 1A~1A(5)
Figure 1B~1B(9)
Figure 2A~3
AI summary
The present invention provides a water-proof sound-transmitting membrane including a polytetrafluoroethylene (PTFE) porous membrane, in which the waterproofness is enhanced further with little lowering of the sound transmittance. The water-proof sound-transmitting membrane includes the PTFE porous membrane. The PTFE, porous membrane includes a first porous layer, and a second porous layer stacked on and integrated with the first porous layer by a binding force acting between PTFE matrices. The first porous layer and the second porous layer each are composed of PTFE with a number-average molecular weight of 5.0 × 107 or more determined by a standard specific gravity method. At least one layer selected from the first porous layer and the second porous layer has an average pore diameter of 1 µm or less. The water-proof sound-transmitting membrane has a surface density of 1 g/m2 to 10 g/m2. The water-proof sound-transmitting membrane has a tensile strength of 10 MPa to 100 MPa. A value obtained by dividing a puncture strength of the water-proof sound-transmitting membrane by the surface density of the membrane is 25 kPa · m2/g to 50 kPa · m2/g.