Black Porous PTFE Membrane With Heat-Stable Whiteness Control
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Solution Overview
Problem
Conventional colored porous PTFE membranes are prone to color fading when exposed to high temperatures or light, which affects their appearance and functionality in applications like electronic device housings.
Innovation Solution
A black porous PTFE membrane is developed with a whiteness of 18.0 to 23.0% on its principal face, achieved through a dyeing process using azine-based dyes with high melting points, and a two-stage stretching method, ensuring the membrane retains its color after heating at 350°C for 1 minute.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a porous PTFE membrane is dyed black to reduce conspicuousness, then the aesthetic quality and design appearance are improved, but the membrane becomes prone to color fading when exposed to high temperature or light
Solution Approach 1:
The patent applies parameter changes by carefully controlling the whiteness value within a specific range (18.0 to 23.0%) after dyeing, and by controlling the stretching conditions (temperature, ratio, and sequence) to optimize the dye fixation and membrane structure. This ensures the membrane achieves adequate black coloration while maintaining color stability under heat and light exposure.
Solution Approach 2:
The patent directly addresses color changes by using a dyeing process that imparts black color to the porous PTFE membrane. The key innovation is achieving a whiteness value between 18.0-23.0% that provides sufficient black appearance while preventing excessive color concentration that would make the dye vulnerable to fading from heat and light exposure.
2Adaptability or versatility
If the membrane is stretched to form a porous structure for gas permeability, then the gas permeation function is improved, but the dyeing uniformity and color consistency become difficult to control
Solution Approach 1:
The patent applies preliminary action by performing the dyeing process before the final stretching step. This sequence allows the dye to be uniformly absorbed by the PTFE membrane while it is in a more compact state, ensuring consistent color distribution. The stretching is then performed after dyeing to create the porous structure, which preserves the uniform dyeing achieved in the preliminary step.
Solution Approach 2:
The patent segments the manufacturing process into distinct stages: forming, preliminary stretching, dyeing, and final stretching. This segmentation allows each process to be optimized independently, ensuring that the dyeing uniformity is not compromised by the stretching process that creates gas permeability.
3Reliability
If the membrane is heated to fix the dye, then the color fastness is improved, but the PTFE membrane structure may deform or the pores may collapse
Solution Approach 1:
The patent applies parameter changes by controlling the heating temperature and duration within specific ranges that are sufficient to fix the dye but below the temperature that would cause PTFE deformation or pore collapse. The stretching temperature and time parameters are also optimized to maintain the porous structure while achieving adequate dye fixation.
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 black porous PTFE membrane exhibits excellent color fading resistance, maintaining its appearance and functionality in harsh conditions, making it suitable for use in electronic devices and other applications where visibility and durability are crucial.
Implementation Method 1
a gas-permeable membrane including a porous polytetrafluoroethylene (PTFE) membrane
Implementation Method 2
allows permeation of gases
Implementation Method 3
azine-based dyes with high melting points, ensuring the membrane retains its color after heating at 350°C for 1 minute
Implementation Method 4
excellent in color fading resistance and that is less subject to color fading caused by heat and/or light
Data Source
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AI summary
Provided is a black porous polytetrafluoroethylene membrane including a porous polytetrafluoroethylene membrane dyed black. A whiteness of a principal face of the black porous polytetrafluoroethylene membrane as measured according to JIS L 1015 (Hunter method) is 18.0 to 23.0%, and the whiteness of the principal face falls within a range of 18.0 and 25.0% after heating at 350°C for 1 minute. This black porous PTFE membrane is suitable as a gas-permeable membrane that blocks entry of water and/or dust and that allows permeation of gases; specifically, the black porous PTFE membrane is suitable, for example, as a waterproof sound-transmitting membrane, a waterproof gas-permeable membrane, and a dustproof gas-permeable membrane.