[Wool Net] Cotton fabric or yarn mercerizing is especially important in improving the quality of cotton products in printing and dyeing. The gloss, dyeing properties, dimensional stability and elasticity of the product after mercerizing are subsequently improved and improved. At present, the most commonly used mercerizing liquid is a concentrated caustic soda solution. Although the hydroxides of other alkali metals such as Li, K, Rb and Se have a certain puffing effect on cellulose, their puffing ability decreases with the increase of atomic weight, and the cost Higher, no practical significance. In addition, some acid and salt solutions such as sulfuric acid, nitric acid, zinc oxide, etc., can expand the fiber dysfunction fiber to obtain a mercerizing effect, but the actual production is difficult and lacks use value. The anhydrous liquid ammonia has small molecular weight, high purity and excellent puffing performance. In the late 60s, the mercerizing research was carried out. The gloss and dyeing properties of the product were not as good as that of concentrated caustic soda, but the feel and dimensional stability were better, so it was often used in finishing. in.
Double filament light refers to two times of mercerizing after the yarn is woven into a fabric, or the yarn is woven into a fabric and then mercerized, or the yarn is twice polished. The specific two-filament method can be used according to the actual situation. In this experiment, the pure cotton white yarn is double-filamented by the existing conditions to explore a better mercerizing process.
1 Experimental part
1.1 Experimental materials, instruments and methods use 8.5 teX singeing yarn, caustic soda, alkali-resistant mercerizing penetrant, etc.; homemade yarn mercerizing frame, single yarn strength meter, microscope, color measuring instrument, etc. Yarn scouring is carried out according to a conventional scouring process. Different concentrations of mercerizing solution were prepared using caustic soda and alkali-resistant mercerizing penetrant. In addition, an I2-KI solution and a 1 M direct lake blue dye solution were prepared.
Yarn mercerizing is done with a self-made mercerizing frame to make a double-filament test of different caustic soda concentration, temperature and time, and at the same time, no tension mercerizing (alkali shrinkage) is used for comparison.
1.2 Performance test The strength test uses a single yarn strength meter to measure the strength of the treated yarn; the dyeing and K/S value are determined by measuring the treated yarn with direct lake blue and then measuring the color to obtain the K/S value. Dyeing performance and adsorption performance, I2-KI experiment is to use the I2-KI solution to color the treated yarn, compare the coloring condition} The gloss judgment mouth is to slice the treated yarn, and observe the cross section to judge the gloss.
2 Results and discussion
2.1 Caustic concentration The strength, dyeing performance and adsorption performance of the yarn after different concentrations of caustic soda twin filament and two alkali shrinkage were measured. The results are shown in Fig. 1 and Fig. 2.
It can be seen from Fig. 1 that when the concentration of caustic soda changes from 180 g/L to 280 g/L, the strength of the double-filament optical yarn gradually increases. When the concentration changes from 280 g/L to 310 g/L, the strength gradually decreases. This indicates that when the caustic soda concentration is 280 g/L, the yarn after double-filament light has the strongest strength. For the two alkali shrinkage yarns, the strength gradually increases when the caustic concentration changes from 180 g/L to 240 g/L. When the concentration is from 240 g/L to 280 g/L, the strength decreases slightly. When I almost invariably changed from 280 g / L to 310 g / L, decreased strength. This shows that when the caustic concentration is between 240 g/L and 280 g/L, the two alkali-shrinked yarns have the strongest strength.
It can be seen from Fig. 2 that when the concentration of caustic soda changes from 180 g/L to 310 g/L, the K/S value of the double-filament yarn has some fluctuation, but from the general trend, when the caustic concentration is 280 g/L. When the K/S value is the largest, the dyeing and adsorption properties of the yarn are the best. For the two alkali shrinkage yarns, when the caustic soda concentration is changed from 180 g/L to 310 g/L, it can be seen that the K/S value is the highest at a concentration of 280 g/L, which indicates that the yarn is at this time. The dyeing and adsorption properties are the best.
It can be seen from Fig. 1 and Fig. 2 that the effect of caustic soda is 280 g/L, whether it is double-filament or two alkali shrinkage. At the same time, it can be seen that the yarn strength after double-filament light is stronger than that of the two alkali-shrinked yarns, but the K/S value is small, that is, the dyeing performance and the adsorption performance are poor. This is because the mercerized cotton fiber is swollen, and the force between the macromolecules is destroyed. Under the action of the tension, the arrangement of the fiber macromolecules tends to be neat, so that the degree of orientation is improved when subjected to an external force. More macromolecules are evenly supported and evenly stressed. The fiber is less likely to break due to a certain macromolecule, and the fibers rearranged by the expansion are closely attached to each other, and the cohesive force is increased, and the fiber is broken or broken due to the slippage of the macromolecule, so the strength is improved. However, the alkali shrinkage yarn is not subjected to the tension during the treatment, and thus the strength is small.
After the yarn is treated with concentrated caustic soda, the fiber swells violently, the crystallinity decreases, the content of the amorphous region increases, and the effect of the dye on the fiber tends to occur in the amorphous region; while the alkali shrinkage is not affected by the tension, the crystallinity decreases. Therefore, the dyeing and adsorption performance of the yarn after two alkali shrinkage is better than that of the double-filament yarn.
2.2 Treatment temperature The strength, dyeing performance and adsorption performance of the yarn after caustic soda double-filament light and two alkali shrinkage at different temperatures are shown in Fig. 3 and Fig. 4.
It can be seen from Fig. 3 that when the treatment temperature is changed from 20 ° C to 40 ° C, the strength of the double-filament optical yarn gradually decreases, indicating that the yarn strength after the double-filament light is maximum at a treatment temperature of 2 ° ° C. For the two alkali shrinkage yarns, when the treatment temperature is changed from 20 ° C to 40 ° C, the strength is also gradually decreased, indicating that the yarn strength of the two alkali shrinkage is also the maximum when the treatment temperature is 2 ° ° C.
It can be seen from Fig. 4 that when the processing temperature is changed from 20 °C to 30 °C, the K/S value of the double-filament optical yarn gradually increases. When the processing temperature is changed from 30 °C to 40 °C, the K/S value gradually decreases, indicating that when the treatment temperature is changed from 30 °C to 40 °C, When the treatment temperature is 3o °C, the K/S value is the largest, and the dyeing and adsorption performance of the yarn is the best. For the two alkali shrinkage yarns, when the treatment temperature is changed from 20 °C to 40 °C, the K/S value gradually decreases, indicating that the K/S value is the highest when the treatment temperature is 2O °C, and the dyeing and adsorption properties of the yarn are the most. it is good.
It can be seen from Fig. 3 and Fig. 4 that whether it is double-filament or two alkali shrinkage, the effect is better when the treatment temperature is between 20 ° C and 30 ° C. The reaction of concentrated caustic soda with cellulose fibers is an exothermic reaction, and the temperature is lower. The more favorable the reaction, but the temperature is too low, on the one hand, the viscosity of the caustic soda solution is significantly increased, so that the caustic soda does not easily enter the fiber to cause surface mercerization. On the other hand, considering the economic benefits, maintaining the low temperature requires considerable power cooling equipment and power consumption, so The temperature should not be too high or too low. In addition, it can be seen that the yarn strength after the double-filament light is stronger than that of the two alkali-shrinked yarns, but the K/S value is small, that is, the dyeing performance and the adsorption performance are poor. The reason is the same as above.
2.3 Treatment time The strength, dyeing performance and adsorption performance of the yarn after caustic soda double-filament light and two alkali shrinkage were measured at different times. The results are shown in Fig. 5 and Fig. 6.
It can be seen from Fig. 5 that when the processing time is changed from 1 min to 5 min, the strength of the double-filament optical yarn gradually rises; when changing from 5 min to 6 min), the strength gradually decreases, indicating that the treatment time is after 5 min. The yarn strength is the same for the two alkali shrinkage yarns.
It can be seen from Fig. 6 that when the processing time changes from 1 min to 5 min, the K/S value of the double-filament optical yarn gradually rises, and the K/S value gradually decreases from 5 min to 6 min, indicating that when the processing time is 5 min. . The yarn after double-filament has the largest K/S value, and the dyeing and adsorption performance of the yarn is the best. For the two alkali shrinkage yarns, the change rules are similar.
It can be seen from Fig. 5 and Fig. 6 that the treatment time is better at about 5 min, whether it is double-filament or two alkali shrinkage. The yarn strength after the double-filament is stronger than that of the two alkali-shrinked yarns, but the K/S value is small, that is, the dyeing performance and the adsorption performance are poor.
2.4 Gloss judgment The processed yarn was sliced ​​to observe the cross section. Determine the change in gloss. Under the microscope, it can be observed that the cross section of the mercerized cotton fiber is round and round, and the cross section after the mercerizing is changed from the waist to the circle. The cross section of the cotton fiber after the alkali shrinking is changed from the waist to the oval. . The difference in concentration, temperature and time of different treatments was not obvious from the microscope.
The cotton fiber undergoes irreversible and intense swelling after being treated with concentrated caustic soda, and the expansion of the fibers is caused by the swelling of the fibers, thereby causing the expansion of the fiber cells. The diameter of the fiber is increased, and the natural distortion of the longitudinal direction of the fiber disappears, at which time an appropriate tension is applied. After the fiber is stretched, the uniformity is improved, the original wrinkles on the surface disappear, the regular reflection is increased, and the intensity of the reflection is increased, so that the fabric exhibits a silky general luster.
2.5 I2-KI experiment The treated yarn was colored with I2-KI solution, and the color was compared. The experimental results show that the color of the alkali shrink yarn is deeper than that of the mercerized yarn, while the unsilched white yarn has no color.
Differences in concentration, temperature and time of different treatments were not observed from this experiment.
Based on the above experimental results, it can be considered that the better mercerizing process is: concentration 280g / L temperature 20 ° C, time 5 mln or concentration 280 g / L, temperature 30 ° C, time 5
Min. On this basis, further experiments were conducted to compare the difference between single-filament and double-filament light. The results are shown in Table 1.
It can be seen from Table 1 that the yarn strength, K/S value and gloss after double-filament light are better than single-filament light, which indicates that the double-filament light can significantly improve the performance of the cotton fiber. However, the performance is better when the temperature is 20 or 30 ° C, which cannot be determined in this experiment.
3 Conclusion
(1) The process conditions of better double-filament light effect are. The concentration is 280 g/L, the time is 5 min, and the temperature is 20~30 °C.
(2) In terms of the strength of the yarn and the improvement of the K/S value, the twin filament light is better than the single mercerizing light, the yarn gloss is brighter, the hand feel is more comfortable, and the wearing performance of the cotton product is greatly improved.
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