Detailed Explanation of The Mercerization Process Principle of Cotton Textile
Cotton products (yarns, Pocketing Fabric
) are treated with a concentrated caustic solution under tensile conditions, and the caustic treatment is then washed away under tension.1. purpose of mercerization
1. Mercerized gloss and brightness improved;
2. Enhanced adsorption capacity, enhanced chemical reaction capacity, and increased the amount of dye obtained;
3. Shrinkage, dimensional stability, fabric flatness improvement;
4. The mechanical properties such as strength and extensibility have been changed.2. Mercerizing process
Classified by process:
1. After bleaching: the mercerizing effect is good, the waste alkali is relatively clean, but the whiteness is poor, easy to stain, suitable for the color cloth, especially the thick fabric.
2. Silk before bleaching: the fabric is easy to be damaged when bleached with good whiteness but poor gloss, suitable for bleaching cloth and printing cloth.
3. Post-dyeing mercerization: it is suitable for the variety that is easy to scratch or not easy to be evenly dyed (after mercerization, the fabric feels hard and dyed relatively fast). In order to improve the fabric surface effect and dyeing fastness, and some varieties with high requirements on gloss, post-dyeing mercerization can also be adopted.(PS: post-mercerization is selective for dyes)
4. Pre-dyeing mercerization and post-dyeing conventional mercerization: to improve the adsorption and chemical reactivity of dyes.The evaluation of mercerizing effect
1. Gloss: one of the main indicators to measure the appearance effect of mercerized fabric.It can be measured by variable Angle photometry, polarized light, etc., but there is no unified ideal test method.
2. The morphological changes of fiber were observed by microscopic sections
3. Adsorption property
(1) barium value method: it is a common method to test the mercerization effect.Barium value of cotton cloth =100, barium value > 150 represents full mercerization, usually 135 ~ 150.
(2) iodine absorption
(3) iodine contamination and staining test method: the samples with different barium values (100-160) were treated with iodine solution h of a certain concentration or direct blue 2B dye solution to make color CARDS, and the iodine contamination and dyeing depth of unknown samples were compared with the color CARDS to quantitatively evaluate the value of mercerized barium.
4. Dimensional stability: the fabric length change before and after treatment is measured by mechanical shrinkage method or dip shrinkage method, and the shrinkage rate is calculated by formula. Generally, the warp shrinkage is higher than latitude, but some varieties with higher warp density produce negative shrinkage rate (door width increases).
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