Recently, people often ask the editor below to tell you the two properties of polytetrafluoroethylene breathable membrane? 1. Air permeability: The air permeability index of the film-coated filter material is mainly provided by the polytetrafluoroethylene breathable membrane. Generally speaking, using high-temperature hot pressing composite process, the air permeability of the filter material after compounding is similar to the air permeability of the film before compounding. Than, the loss is about half.
Of course, if the adhesive composite method is used, the air permeability will be lost even more.
However, if the air permeability is too high, it often indicates that the pore size of the microscopic network structure of the film is too large, which affects the filtration efficiency of the filter material. Therefore, in practical applications, higher air permeability is not always better.
2. Compositeness: The composite fastness of membrane-coated filter materials has always been a problem for filter material manufacturers.
Because the PTFE breathable membrane is very thin and its strength is much weaker than the base material, it is impossible to use peel strength to measure its composite fastness like ordinary composite materials.
Currently, the composite fastness testing methods used by domestic and foreign manufacturers include tribometer testing, hydrostatic pressure resistance testing, etc.
The specific test method is to fix the coated side of the coated filter material sample upward (outward) on the mouth of a test cup with a mouth diameter of 25mm, and continuously feed 250°C gas into the cup to gradually Increase the pressure on the uncoated side of the film-coated filter material. When the long side dimension D (mm) of the bubble after the film is peeled off begins to exceed 2.5mm, record the gas pressure (MPa) in the test cup. The pressure That is the film fastness of the film-coated filter material.
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