Reasons and countermeasures for poor waterproof and oil-proof durability of finished fabrics:
1.Differences between waterproof and oil-repellent agents:
The mass fraction of effective organic fluorine among waterproof and oil-repellent agents is different, and the surface potential is also different, resulting in differences in the durability of processing. The higher the content of available organic fluorine, the lower the potential, and the better the sustainability of the process. Most fiber surfaces show negative values and the pH value decreases. The surface potential of polyester fibers tends to approach zero. The surface potential of nylon fibers changes from negative values to positive values, and the change of cotton is small. The greater the potential difference between the waterproof and oil-repellent agent and the fiber surface, the faster the adsorption, and the faster the processing sustainability will decline. For this reason, 10% glacial acetic acid 0.5-1.5g/l can be added to improve its performance.
2.Wet cloth processing:
In many printing and dyeing factories, wet cloths that have just been dyed are centrifuged and dehydrated and directly processed for waterproofing and oil-proofing. The fabric has a large liquid-carrying rate, and the cloth surface preferentially absorbs the large molecules of the waterproof and oil-proofing agent. Part of the moisture on the cloth surface flows back to the surface after the padding process. In the working tank, the mass fraction of the waterproof and oil-proof agent decreases, and the waterproof and oil-proof effect also decreases. Therefore, fresh waterproof and oil-proof working fluid must be replenished in a timely manner during continuous processing (it is recommended that dry cloth be treated with waterproof and oil-proof treatment, because the cloth surface will have a saturation value for absorbing liquid, and when the saturation value is reached, the cloth surface will no longer absorb liquid) .
3.Fabric structure:
The looser the fabric structure or the greater the weight, the greater the liquid absorption capacity, and the waterproof effect will decrease faster during continuous processing; on the contrary, it will be better.
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