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chemical substances can coat either glass filament yarns
or fabrics. Major applications are:
- PVC coated yarns
for sun and insect screening.
- PTFE coated fabrics
for high end printed wiring boards (low dielectric constant / low
losses), architectural and roofing membranes. Specific properties
of PTFE fabrics as non-stick and smooth surface, resistance to chemicals,
compliance with food regulation, temperature resistance, high tensile
strength serve a wide range of applications including food processing,
conveyor belts, release sheets, thermal insulation, sealing...
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PVC coated yarns:
Single yarns pulled from a creel are drawn through a PVC jet or bath
and a die to form the desired round section shape. Then the coated
yarn is dried and thermally cured in a continuous oven and wound onto
a paper tube to make products suitable for further textile operations
like beaming, weaving. Required properties of single yarns are high
twist to promote round section, high tensile strength, compatibility
with PVC in order to avoid part of yarn with no coating.
PTFE coated fabrics:
Glass fabrics are impregnated on a finishing line with PTFE dispersion.
The coating layer build up occurs in three steps: elimination of water,
removal of dispersion surfactants to 250° /280°C, sintering
to 450°C (842°F). The impregnation process can
be repeated till 8 times in order to reach the required PTFE thickness.
Other chemicals can be added to impart specific properties. Additional
partial heat cleaning is also sometimes processed
in order to suit the required color of fabric.
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EC9 34 Z40 (G150) Saint-Gobain Vetrotex yarns
sized with the TD24M size system, suits very well the requirements
for PVC single
yarn coating."
All the Saint-Gobain Vetrotex sizes designed for heat cleaning, perform
superbly for the PTFE coating fabric process. Plied
yarns
are often used especially those based on EC-9 136 Z28 T8G NV (ECG37
1/0 0.7Z T8GNV) and EC-9 204 Z20 T8G (EC-9 25 1/0 0.5Z
T8G)
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