Effect of silicone oil on the setting of dyed fabrics

The visual expression of silicon spot on the fabric surface is that there are oil spots as small as needle tip and as large as rice grain. Under extreme conditions, the area may be larger. Sometimes, the oil spot has a certain color because of floating color. This spot is like a small wet spot, soft and without grain feeling. It is extremely difficult to find and remove before drying. The reason is that it is caused by silicone oil demulsification bleaching oil, which often occurs after finishing and water washing.
Formation of silicon spot
Mysterious veil of silicone oil and waterproof agent molecules
1. Molecular structure of common silicone oil

2. Molecular structure of waterproof agent

3. Effect diagram and schematic diagram of finishing agent on fabric surface

The cause of silicone oil stain
1. Alkalinity
During the pretreatment of cotton fabric, alkali with higher concentration is usually used to remove impurities from the fabric (especially mercerization alkali is used more). It is not easy to clean the alkali when it enters the fiber, and alkali should also be added during dyeing (reactive vat dyes), so the cloth surface may be alkaline during the finishing.
However, chemical fiber fabrics must be restored and cleaned after dyeing. At present, printing and dyeing plants are still using sodium hydrosulfite and caustic soda for cleaning. If they are not cleaned after dyeing, it will also cause alkali on the surface of soft cloth before dyeing. However, ordinary silicone oil is not alkali resistant and will break its emulsion under alkaline conditions, which is the reason why the mill sticks to the roll after passing thousands of meters during the dip rolling process. Therefore, before softening, the alkali agent must be cleaned or acetic acid must be added to the working solution to keep the groove PH5-6.

For more information on silicone oil, please refer to the website: http://www.siliconeoil.net