Although strong alkali and weak acid salts can degum silk without damaging silk fibroin, they do not have the ability to remove oily wax and pigment from silk, nor can they evenly disperse the removed sericin and impurities in the scouring solution, which will not cause secondary pollution to the fiber, and long-term alkali treatment will make the degummed fabric feel rough and hard. Therefore, when degumming, alkali is combined with surfactants such as soap and synthetic detergent. Common degumming method: soap-alkali synthetic washing method.
Enzymatic degumming: Alkaline proteolytic enzymes are often used for desizing. Mechanism: Alkaline proteolytic enzymes can catalyze the hydrolysis of polyamino acid bonds in sericin molecules, making sericin a soluble bleaching agent, peptide and so on. And then further catalytic hydrolysis is carried out to generate amino acids, so as to achieve the purpose of degumming by washing. In this process, there is no effect on silk fibroin. Because of the specificity of the enzyme, it only catalyzes the hydrolysis of sericin and cannot remove other impurities except sericin. Moreover, the decomposed sericin, especially the internal sericin, can not be well separated from the silk fibroin body, and can be simply removed by washing with water. Therefore, the effect of pure enzymatic degumming is not ideal, and it needs emulsification and cleaning with soap and synthetic detergent to effectively remove sericin, wax and pigment.