What Chemicals Are Used for Wool Mercerizing?

Wool mercerizing is an important process that can improve the performance and appearance of wool fibers. The following are some commonly used chemicals in wool mercerizing:

1. Alkali
①Sodium hydroxide (caustic soda)
Effect: Sodium hydroxide is one of the most critical raw materials in wool mercerizing. In the appropriate concentration and conditions, it can make the wool fiber scale layer expansion, softening so that the fiber becomes smoother and the gloss is significantly improved. At the same time, alkali treatment can also change the internal structure of wool fibers and improve the elasticity and strength of the fibers.
Attention: However, due to the strong alkalinity of sodium hydroxide, the concentration, temperature and processing time must be strictly controlled when using it, otherwise, it will easily lead to excessive damage of wool fibers, and problems such as decrease of fiber strength and roughness of hand feeling will occur.
②Potassium hydroxide
Effect: Potassium hydroxide is similar to sodium hydroxide, which is also a strong alkaline substance used in wool mercerizing and can also make wool fiber scale layer expansion. Compared with sodium hydroxide, potassium hydroxide in some cases may be slightly less damage to wool fibers, and in some special mercerizing processes, potassium hydroxide can provide better treatment effects.

2. Salts
①Sodium chloride (NaCl)
Effect: In the process of wool mercerizing, sodium chloride mainly plays an auxiliary role. It can regulate the electrolyte concentration of mercerizing liquid, which helps to control the degree of expansion of wool fiber. To a certain extent, it can also stabilize the mercerizing process to prevent fiber damage or poor mercerizing effect caused by too high or too low electrolyte concentration.
②Sodium sulfate (Na2SO4)
Effect: Sodium sulfate is similar to sodium chloride and is also an electrolyte. It can balance the ionic concentration in mercerizing liquid, improve the penetration performance of mercerizing liquid so that the mercerizing agent can better penetrate the inside of wool fibers, thus improving the mercerizing effect. At the same time, sodium sulfate can also improve the gloss and softness of wool fiber to a certain extent.

3. Mercerizing agent
①Cation mercerizing agent
Effect: The cationic mercerizing agent can be with the anionic groups on the surface of wool fiber electrostatic attraction, so as to adsorb on the surface of the fiber. These mercerizing agents can further improve the luster and feel of wool fibers, making the fibers smoother and softer. At the same time, the cationic mercerizing agent can also form a protective film on the surface of wool fibers, improving the fiber's antistatic properties and wear resistance.
②Amphoteric mercerizing agent
Effect: amphoteric mercerizing agent contains cationic and anionic two groups, this special structure makes it in the wool mercerizing process has better adaptability. They can not only interact with the anionic groups on the wool fiber but also react with other additives or impurities in the cationic groups to achieve a better mercerizing effect. Amphoteric mercerizing agent can effectively improve the wool fiber's luster, feel, and dimensional stability.

4. Softener
①Silicone softener
Effect: After the wool mercerizing, to make wool fibers have a better feel, usually use silicone softener. Silicone softener can form a layer of soft, slippery film on the surface of wool fibers, reducing the coefficient of friction between the fibers so that wool fabrics feel softer and fuller. At the same time, this film can also play a certain waterproof, anti-fouling effect, improving the performance of wool fabrics.
②Fatty acid ester softener
Effect: fatty acid ester softener is also a commonly used softener, it can penetrate the wool fiber, lubrication and finishing of the fiber. This softener can effectively improve the softness and elasticity of wool fibers so that wool fabrics have better drape and wearing comfort.

5. Reducing agents
①Sodium sulfite
Effect: In the wool mercerizing process, sodium sulfite can be used as a reducing agent. It can remove some oxidized impurities on the surface of wool fiber, restore some disulfide bonds in wool fiber, and make the fiber softer and fluffy. At the same time, sodium sulfite can also prevent excessive oxidation of wool fiber in the mercerization process, playing a certain protective role.
②Sodium bisulfite 
Effect: Insurance powder is a strong reducing agent, mainly used for bleaching and reducing treatment in wool mercerizing. It can remove the pigment and impurities on wool fiber so that the whiteness of wool fiber is improved. At the same time, the insurance powder can also restore some coloring groups in wool fiber, further improving the color and appearance of wool fiber. However, insurance powder needs to be used with special care, as it is chemically active and prone to decomposition and spontaneous combustion.

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