1. Lye concentration: the main factor affecting the mercerizing effect
(1) After the cotton fiber is treated with different concentrations of caustic soda solution, the change of length and diameter: When the concentration is more than 8%, the diameter increases, and the length shortens to the maximum.
(2) The shrinkage and dyeing strength of cotton yarn in different concentrations of NaOH solution
(3) The concentration requirement of cotton mercerization (the relationship between C and shrinkage and barium value) When C=177g/L, the barium value is 150, C=245g/l, and the barium value: the highest. C=240~280g/l, the shrinkage tends to be stable.
In actual production, it can be selected according to the quality of semi-finished products and the quality requirements of finished products.
2. Tension
(1) The effect of tension on fabric gloss: When cotton fabric is treated with concentrated alkali, only by adding proper tension can it show good gloss. From the effect of tension on the performance of cotton yarn after mercerization, it can be seen that: high tension, good gloss .
(2) The effect of tension on the mechanical properties and adsorption properties of the fabric: that is, under the condition of weak, the strength of cotton yarn has been improved, if appropriate tension is applied, its strength can be further improved, but the increase in gloss is not much, and The elongation at break and the adsorption performance have declined.
(3) The effect of tension on the shrinkage rate of the fabric: When mercerizing, the warp and weft tension has an extremely important effect on the shrinkage rate of the fabric.
3. Temperature
The role of caustic soda and cellulose fiber is an exothermic reaction, so increasing the temperature of the lye has the effect of weakening the swelling of the fiber, thereby reducing the mercerizing effect, which is manifested in the shrinkage and barium value. Therefore, the low temperature of mercerizing lye is better, but the actual production Taking into account the economic benefits, and the increase in the viscosity of the lye when the temperature is too low, it is difficult for the reduced liquid to penetrate into the yarn and fabric, and it is more difficult to expand the width. Therefore, the cold running water is usually used to cool the lye through the interlayer of the rolling groove. Can.
4. Time
The mercerizing function is to make the caustic soda quickly and evenly and fully penetrate into the cotton yarn or fabric and act on the fiber, so a certain time must be guaranteed.
The cotton yarn was mercerized with 280g/l NaOH under no tension. It was found that the shrinkage rate and dye absorption rate of the yarn reached the maximum within 20s, and the extension of time was not significant for improving the mercerizing effect.
5. Dealkalization
Dealkalization has a great influence on the setting effect of mercerizing. If there is more than 5% alkali on the fabric after the tension is relaxed, the fabric will still shrink, which will affect the gloss and weft shrinkage.
The alkali removal is carried out in two steps: ①In the case of widening, use the flushing device to rinse the fabric with hot dilute alkali; ②After relaxing the weft tension, enter the alkali removal box and wash and steam with light alkali.
