Mercerizing is a process in which cotton products (yarn, fabric) are treated with concentrated caustic soda solution under tension and then washed out of caustic soda under tension. After treatment, the roundness of the fiber increases, the smoothness of the surface and the optical properties are improved, and the intensity of the reflected light is increased.
Why should cotton and its blends be mercerized?
Cotton fiber products have been loved by people for a long time because of its good hygroscopic property, soft hand and comfortable touch when contacting with human body. But the untreated cotton fabric is easy to shrink, wrinkle and poor dyeing effect. Mercerizing can improve these shortcomings of cotton products.
Improve fabric quality
There are obvious differences in appearance and hand feeling between the treated cotton and its blends, such as T-shirt, button shirt, jacket and skirt. The appearance of mercerized products shows a texture similar to cotton, silk and non silk; the handle is soft and comfortable; the color is plump and attractive.
It can improve the dyeing performance of fabrics
The dyeing or printing of cotton cloth mostly adopts reactive dye dyeing process. After mercerizing, the physical and chemical changes of cotton fiber can greatly increase the color yield of reactive dye and save dyeing and chemical materials. In the production of medium dark products, especially black, dark blue, dark green, coffee, etc., mercerization must be used to produce high-quality products.
It can increase the moisture absorption and elasticity of the fabric
After mercerizing, the moisture absorption and elasticity of the fabric are obviously increased. It is the first choice for vests, sweatshirts and other sportswear fabrics.
The change of cotton after mercerizing
structure performance
① The cross section of pure cotton is waist circle, and that of mercerized cotton is circle.
② Pure cotton has natural twist, the surface wrinkles of mercerized cotton disappear and become smooth.
physical property
① The luster of mercerized cotton is better than that of pure cotton;
② The strength of mercerized cotton is higher than that of pure cotton;
③ The dimensional stability of mercerized cotton is better than that of pure cotton.
Chemical properties
① The reactivity of mercerized cotton increased (the amorphous area increased, and the hydroxyl group changed from inaccessible to accessible with the rotation of the main valence bond);
② The adsorption capacity of mercerized cotton to water, iodine, barium hydroxide and dye is larger than that of pure cotton.
Types of mercerized cotton
According to different mercerizing objects, mercerized cotton can be generally divided into yarn mercerization, fabric mercerization and double mercerization.
Yarn mercerizing: refers to a special kind of cotton yarn with the original characteristics of cotton and the general luster of silk after the treatment of high concentration caustic soda or liquid ammonia under the condition of tension.
Fabric mercerizing: refers to cotton fabric with tension, after high concentration of caustic soda or liquid ammonia treatment, to make the fabric glossiness better, straighter and better shape retention.
Double mercerizing refers to the process of making a fabric from mercerized cotton yarn, and then mercerizing the fabric to make the cotton fiber fully and irreversibly swell in the concentrated alkali. The treated fabric has a smooth surface with silk like luster, and its strength, anti pilling and dimensional stability are improved to varying degrees.