What are the main factors affecting the mercerizing process?

The basic conditions of the mercerizing process are the concentration, temperature, action time, tension and alkali removal of NaOH solution.

1. The concentration of lye

The main factors affecting the mercerizing effect

① Changes in length and diameter of cotton fibers treated with different concentrations of caustic soda solution:

Concentration>8%, the diameter increases, the length shortens to the maximum

②The shrinkage and dyeing force of cotton yarn in different concentrations of NaOH solution

③Concentration requirements of cotton mercerizing (relationship between C and shrinkage and barium value)

When C=177g/L, the barium value is 150, and when C=245g/L, the barium value is the highest.

C=240~280g/l, the shrinkage tends to be stable.

Therefore, the most suitable caustic soda concentration for mercerizing is about 245g/l. Considering the factors such as the alkali absorption of the fabric itself and the alkali consumption of acid gas in the air, the mercerizing alkali concentration of cotton is 260-280g/l. 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 the luster of the fabric

When cotton fabric is treated with concentrated alkali, only with appropriate tension can it show good luster. From the effect of tension on the performance of cotton yarn after mercerization, it can be seen that the tension is large and the luster is good.

2), the effect of tension on the mechanical properties and adsorption properties of fabrics

That is to say, the strength of the cotton yarn has been improved under the weak condition. If the appropriate tension is applied, the strength can be further improved, but the increase in gloss is not much, and the elongation at break and adsorption performance are decreased.

3) The effect of tension on fabric shrinkage

When mercerizing, the warp and weft tension plays a very important role in the shrinkage of the fabric.

In actual production, the warp and weft shrinkage rates of fabrics of various specifications are unbalanced. For fabrics with high warp density such as khaki and Futiao, the warp shrinkage greatly exceeds the weft shrinkage, so the warp tension is given priority; while a thin fabric such as plain cloth is just the opposite.

3. Temperature

The effect of caustic soda and cellulose fibers is an exothermic reaction, so increasing the temperature of the lye solution has the effect of reducing the swelling of the fibers, thereby reducing the mercerizing effect, which is manifested in the decrease of shrinkage and barium value, so the mercerizing lye is better at low temperature, but the actual production Considering the economic benefits and the increase in the viscosity of the lye when the temperature is too low, it is difficult for the reducing liquid to penetrate into the yarn and fabric, and it is difficult to expand the width. Can.

4. Time

The mercerizing effect is to make the caustic soda penetrate into the cotton yarn or fabric quickly and evenly and fully and act on the fiber, so a certain period of time must be guaranteed.

The cotton yarn was mercerized with 280g/l NaOH under no tension, and it was found that the yarn shrinkage rate and dye absorption rate reached the maximum value in 20s, and the effect of increasing the mercerization was not significant by prolonging the time. In addition, the time is related to the alkali concentration and temperature. When the concentration is low, the action time should be appropriately extended; generally 50-60s is used.

5. De-alkali

Alkali removal has a great influence on the setting effect of mercerizing. If there is more than 5% alkali on the fabric after relaxing the tension, the fabric will still shrink, thereby affecting the gloss and the weft shrinkage. Alkali removal is carried out in two steps: ①In the case of expansion, use a flushing device to rinse the fabric with hot dilute alkali; ②After relaxing the weft tension, enter the alkali removal box, wash and steam with light alkali.