Development of super-high shrinkable acrylic top wool

Development of Ultra-high-shrink Acrylic Expanded TOPS HUANG Hong-hua YANG Li-hua XU Gui-cheng (Acrylic Fiber Factory, Daqing Petrochemical Company, Daqing 163714, Heilongjiang, China) The process conditions for the selection of pull-off machines using the orthogonal test method for acrylic tops are: hot-plate temperature 150C, filament bundle shrinkage With a rate of 20% and a draw ratio of 1.46, the shrinkage of the tops produced is 35%. Other quality indicators meet or exceed the standards of the Ministry of Textiles. At present, the shrinkage of high shrinkable acrylic tops used in China is mostly lower than 24%. The user has a certain demand for ultra-high shrinkage acrylic expanded tops. The acrylic fiber factory of Daqing Petrochemical Company used the existing equipment and technological conditions to test and develop a 3.33dtex ultra-high shrinkage bulkhead with a steam shrinkage rate of more than 35%.

1 Test 1.1 Materials The quality specifications of the 3.33dtex high-shrinkage acrylic filament yarn produced by the Daqing Petrochemical Company's acrylic fiber factory are shown in Table 1. Table 1 Quality standards of acrylic filament bundles Item Item Deviation Deviation Boiling Water Shrinkage, Strength Oil Content, Elongation 1.2 Process Process HL-6 Carding Machine > Baler 2 Results and Discussion According to the principle of expansion of acrylic fibers, to increase the shrinkage rate of the tops, the potential shrinkage of the high shrinkage fibers must be greater, the greater the potential shrinkage, the greater the degree of retraction of the expanded tops. The larger the shrinkage, the higher.

High-shrinkage fibers in the tops manufacturing process are achieved by the hot-stretching of the filament bundles. According to the polymerization principle and production practice of acrylonitrile, there are two main reasons that affect the shrinkage of the bulked wool: raw materials and pull 21 raw materials to tops Impact of shrinkage 21.1 Shrinkage of raw materials Filament shrinkage mainly depends on the content of the second monomer in the polymer. Conventional acrylic fiber forms a strong CN-CN between macromolecules and macromolecules due to polar nitrile groups. The interaction between molecules and bonds is large, the rotation in the molecular chain is difficult, the main chain has a large rigidity, and the fiber tow has a brittle texture and lacks elasticity. This type of fiber is more difficult to produce into high shrinkage tops. The addition of the second monomer increases the elongation of the fiber, which facilitates the smooth progress of the hot stretching.

21.2 Raw material quality The quality of acrylic filaments has a great influence on the shrinkage of the tops. Filament elongation, boiling water shrinkage, fineness and other quality indicators are particularly important. The strength of the fiber is low, and it will prematurely break when it is stretched. The fiber's denier will increase the total fiber's fineness. Stretching is difficult. When there are hard wires and filaments in the filament, it will produce a large number of hair particles and hair pieces. Wait.

22 The effect of the breaking process on the shrinkage rate 22.1 The thermal stretching multiple Under certain conditions, the larger the thermal stretching ratio of the pull-puller, the greater the tension applied to the fiber tow, and the more deformation occurs in the high-elastic state of the fiber. Larger, the higher the shrinkage.

22.2 Cooling effect of stretcher During the hot stretching process, the movement of fiber molecules and the friction between the fibers and the roller and the friction between the roller and the fiber generate a certain amount of heat, which exceeds a certain limit. It is easy to reduce the potential shrinkage of the fiber obtained by hot stretching. Therefore, the circulating cooling water is introduced to the roller to lower the surface temperature of the roller, so that the fiber having a certain potential contraction is cooled under tension. The orientation of the curled macromolecules in the amorphous region is stretched and frozen, and the segmental motion of macromolecules is temporarily stopped, resulting in high potential shrinkage and low shrinkage. It is required to pull the machine cooling cooling water inlet temperature 11c, the outlet temperature 13~22. 3 hot plate temperature puller hot plate temperature is determined by the acrylic glass transition temperature of the acrylic glass at 80100 °C, and ultra-high shrinkage The development of body tops mainly depends on the second glass transition temperature of acrylic fibers. Therefore, when the temperature of the hot plate is generally 130~, the heating effect of the tow is good, and the elongation of the fiber is changed to a high elasticity to increase the strength of the main fiber. Fiber shrinkage increased.

3 choose to pull off the process conditions to increase the shrinkage of the wool strips need to control the pull stretcher thermal stretching times, hot plate temperature and select the appropriate filament shrinkage, for which the use of orthogonal test to select the appropriate parameter values ​​were selected three levels of data As experimental factors, see Table 2 Table 2 Wool Shrinkage Orthogonal Test Factor Level Table Horizontal Hot Plate Temperature/C Steam Shrinkage Ratio, Heat Stretching Ratio According to the orthogonal test table, three factors and three levels can be tested with L9. The test results are shown in Table 3. According to Table 3, the process parameters for the pull-off machine are determined according to Table 7. According to this process, the steam shrinkage of the acrylic high-shrink tops are all higher than 35%. Table 3 The results of the orthogonal test of the shrinkage rate Three-factor three-level arrangement Design hot-plate temperature boil hot water stretching degree/C shrinkage ratio, steam shrinkage ratio of multiple tops, e% 4 ratio of regular strips and high shrink strips Mix ratio of high shrink strips to regular strips should be to meet the expansion top The quality requirements are determined, and the relationship between the content of the high shrinkage strips and the shrinkage of the expanded strands and the relationship between the blending ratio of the high shrinkage fibers and the diameter of the bulked yarns are obtained through the process experiment. When the content of the high shrinkage fibers exceeds 40%, the bulked wool The shrinkage rate is very small and has little effect on the shrinkage rate of the expanded tops. When the content of the shrinkage strips is between 45% and 50, the expanded yarn has the largest diameter and the best expansion effect; when it exceeds 50, the diameter changes. Small, the elasticity of the yarn is relatively reduced, and the feel is not good. In the actual production, when the mixing ratio of the regular strip and the high shrinkage strip is 60:40, the expanding effect of carding into the expanded top is relatively satisfactory, and the shrinkage rate reaches 35%, other indicators have reached 3.33dtex high shrinkage rate standard for expanded wool tops, product quality indicators in Table 4 Table 43.33dtex high quality shrinkage bulky top quality indicators average item weight deviation / uneven weight rate , E% average length deviation rate, long hair rate, short hair rate, hair particles / hair pieces / only. M-steaming shrinkage, e% Implementation of the standard test results 7 7 3 Conclusion Select the raw materials with high shrinkage, stable elongation and good quality indicators to ensure that the shrinkage rate of the ultra-high shrinkage swelled wools exceeds 35%. The greater the extension ratio, the higher the shrinkage of the fiber, and the thermal stretching ratio is determined by the shrinkage and elongation of the filament. Generally, 1.42 to 1.46 is more appropriate. One of the factors. The shrinkage rate of the ultra-high shrinkable tops with a hot plate temperature controlled at 130~ is more than 35%, and it is relatively stable.

Summer Short Sleeves

Summer short sleeves: