Ptfe films are prepared by biaxial tensile
method. Scanning electron microscope can observe that the films are made of
crisscrossing fiber filaments connected with each other, and the gaps between
fiber filaments form microholes in the films.
There are many micropores on the surface of
the film, about 9 billion micropores per square inch, and the micropores are
mainly distributed in the diameter of 0.8~1 micron. The minimum pore diameter
of thin film micropores is only about 0.6 micron, while the maximum pore
diameter is about 1.6 micron, and the diameter of water vapor is 0.0004 micron.
Thus, water vapor molecules can easily penetrate the pores, allowing the
membrane to function as a moisture permeator. The smallest liquid you can get
your hands on is light fog, with droplets 20 microns in diameter. Therefore,
the membrane also has the function of waterproof. The moisture permeability of
ptfe film is 8450g/m2·24h, which is much higher than that of 3000g/m2·24h when
human body feels comfortable. At the same time, the ptfe film also has good
wind resistance. When the wind pressure rises to the equivalent of wind
pressure of level 10, the permeability of the film is 28.85mm/s, while when the
permeability exceeds 30mm /s, the film loses its wind resistance.
Polyamide (COPA) hot melt adhesive as the
adhesive, the use of flat vulcanizing machine will be fabric, hot melt
adhesive, ptfe film, hot melt adhesive, lining five layers by hot pressing made
of waterproof and permeable laminated fabric. Orthogonal tests of nine
laminating processes with four factors and three levels were carried out. Under
the condition of nine kinds of technology of laminated fabric including
moisture permeability, peel strength, high hydrostatic pressure and
permeability test, finally USES the grey nearly optimal theory to deal with
data process 2 for the optimal process, namely between the fabric and ptfe film
gluing quantity to 12 g/m2, the material between the membrane and the amount of
glue is 24 g/m2, laminating temperature is 140 ℃, laminated time of 10 s, to achieve the
optimal performance of the laminated fabric.
The properties of laminated fabrics made of
four kinds of different fabrics are compared. It is found that the three most
important properties of the composite fabrics, namely moisture permeability,
heat preservation and peeling strength, are superior. Therefore, it is more
ideal to choose brocade and cotton interweave as the layer of waterproof and
moisture permeable laminated fabric. In the use of water-soluble adhesive, the
surface of the material wetting, and other substances between the bond
strength.
In order to further improve the peeling
strength of laminated fabric, ptfe film was treated with hydrophilic
modification. In the process of modification, 1ml Fe Cl3 solution was used to prepare
Fe(OH)3 colloid, which had the best treatment effect on the film. The optimal
solution for the ptfe film
repolymerization of hydrophilic monomer acrylic acid adsorbed with Fe(OH)3
colloid is A3B2C1D2, that is, the polymerization temperature is 70℃, the acrylic monomer
concentration is 20%, the polymerization time is 20min, and the initiator
dosage is 1%.In addition to a slight decrease in moisture permeability,
hydrostatic pressure resistance and permeability rate, the peel strength value
of the laminated fabric after modification was greatly improved and reached the
enterprise standard of 5N/2.5cm.
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