Development of ultra-high shrinkage acrylic expanded tops Huang Honghua Yang Lihua Xu Guicheng (Daqing Petrochemical Company Acrylic Fiber Factory, Daqing 163714, Heilongjiang Province) Acrylic expanded tops The orthogonal test method is used to select the cutting process: hot plate temperature 150C, filament bundle shrinkage The rate is 20%, the draw ratio is 1.46, and the shrinkage rate of the produced top is 35%. Other quality indicators meet or exceed the standards of the Ministry of Textiles. At present, the shrinkage of high-shrinkage acrylic expanded tops used in China is mostly less than 24%. The user has certain demand for ultra-high shrinkage acrylic expanded tops. Daqing Petrochemical Company's acrylic fiber plant uses the existing equipment and process conditions to test and develop 3.33dtex ultra-high shrinkage expanded tops with a steaming shrinkage of more than 35%. 1 Test 1.1 Raw material Daqing Petrochemical Company Acrylic Fiber Factory production of 3.33dtex high shrinkage acrylic filament yarn bundle quality indicators are shown in Table 1 Table 1 Acrylic filament filament bundle quality standard project indicators project fineness deviation boiling water shrinkage rate, strength oil content, elongation 1.2 process Process HL-6 carding machine>Packer 2 Results and discussion According to the bulking principle of acrylic fiber, to increase the shrinkage rate of tops, the potential shrinkage of high-shrinkage fibers must be achieved. The greater the potential shrinkage, the degree of retraction of the expanded tops. The larger the shrinkage, the higher the shrinkage rate. In the top manufacturing process, the high shrinkage fiber is realized by hot stretching of the filament bundle. According to the polymerization principle and production practice of acrylonitrile, there are two main reasons for affecting the expansion ratio of the expanded top: raw material and pulling 21 raw material to the top Effect of Shrinkage 21.1 Raw Material Shrinkage The shrinkage of the filament is mainly determined by the content of the second monomer in the polymer. The conventional acrylic fiber forms a strong CN-CN between the macromolecule and the macromolecule due to the polar nitrile group. The bond, the interaction between the molecules is large, the rotation in the molecular chain is difficult, the main chain has a large rigidity, the fiber tow is brittle in texture, lacks elasticity, and the fiber is difficult to manufacture into a high shrinkage top. By adding the content of the second monomer, the elongation of the fiber is increased, which is favorable for 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 tops. Quality indexes such as strength elongation, boiling water shrinkage, and fineness of the filament are particularly important. The strength of the fiber is low, and it breaks prematurely when stretched. The fineness of the fiber is too large to increase the total fineness. It is difficult to stretch. When there is a hard filament in the filament bundle and the filament is formed, a large amount of wool and flakes are produced. Wait. Effect of 22 breaking process on shrinkage rate 22.1 Hot drawing multiple Under certain conditions, the greater the thermal stretching factor of the drawing machine, the greater the tension applied to the fiber tow, and the more the deformation of the fiber occurs in the high elastic state. Large, the higher the shrinkage rate. 22.2 Cooling effect of the breaking machine During the hot drawing process, the movement of the fiber molecules and the pressure between the rollers, between the fibers, and between the rollers and the fibers, 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 with a certain potential shrinkage is cooled under tension. The macromolecular orientation of the amorphous region is frozen after being stretched, and the segmental motion of the macromolecule is temporarily stopped, the potential shrinkage is high, and the shrinkage loss is small. It is required to cut the cooling water inlet temperature 11c, and the outlet temperature is 13~22.3. The hot plate temperature of the hot plate is determined by the vitrification temperature of the acrylic fiber. The glass transition temperature of the acrylic fiber is 80100 °C, and the ultra-high shrinkage expansion. The development of the body tops mainly depends on the second glass transition temperature of the acrylic fiber. 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 becomes high with the elastic shape, so that the elongation of the fiber is increased. The fiber shrinkage rate is increased. 3 Selecting the breaking process conditions to increase the slender shrinkage rate requires controlling the hot drawing multiple of the breaking machine, the hot plate temperature and selecting the appropriate filament shrinkage rate. For this purpose, orthogonal test is used to select the appropriate parameter values ​​and three levels of data are selected respectively. As experimental factors, see Table 2 Table 2 top shrinkage rate orthogonal test factor level table horizontal hot plate temperature / C steaming shrinkage rate, thermal stretch multiple according to the orthogonal test table, three factors, three levels can be tested with L9, The test results are shown in Table 3. According to Table 3, the process parameters of the pull-off machine are determined according to Table 3. According to this process, the steam shrinkage rate of the acrylic high-shrinkage tops is higher than 35%. Table 3 The shrinkage rate of the orthogonal test results The three-factor three-level arrangement Design hot plate warm wire boiling water hot stretching degree / C shrinkage rate, multiple tops steaming shrinkage rate, e% 4 normal strips and high shrinkage strip ratio of high shrinkage strips and regular strips should be mixed to meet the bulk tops Determined by the quality requirements, the relationship between the content of high shrinkage strips and the shrinkage of expanded tops and the relationship between the mixing ratio of high shrinkage fibers and the diameter of bulked yarns through process experiments. When the content of high shrinkage fibers exceeds 40%, the expanded hair The shrinkage rate is rarely increased, and the shrinkage rate of the expanded tops is not so high. When the content of the shrinkage strips is 45% to 50, the diameter of the spun yarn is the largest and the expansion effect is the best; when the diameter exceeds 50, the diameter is changed. Small, the elasticity of the yarn is relatively reduced, and the hand 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 puffing effect of the carded into the expanded top is ideal, and the shrinkage rate is reached. 35%, all other indicators have reached the 3.33dtex high shrinkage expansion tops enterprise standard, product quality indicators see Table 4 Table 43.33dtex ultra-high shrinkage expansion top quality index items average bar weight deviation / bar weight unevenness rate , e% average length deviation rate, long hair rate, short hair ratio, wool / flakes / only. M-steaming shrinkage rate, e% implementation of standard test results, 7 3 Conclusions Selecting raw materials with high shrinkage, stable elongation, and good quality indicators can ensure that the ultra-high shrinkage expanded tops shrinkage rate reaches 35% or more. The larger the draw ratio, the higher the fiber shrinkage rate, and the hot draw ratio is determined by the shrinkage rate and elongation of the filament. Generally, the choice of 1.42~1.46 is suitable. One of the factors. The hot plate temperature control of the ultra-high shrinkage tops of 130~ shrinks more than 35% and is relatively stable. Custom Cushion Covers,Grey Christmas Cushions,Large Childrens Cushions,Small Childrens Cushions Nantong NATASHA Textiles Co.,Ltd. , https://www.ntnatashatextile.com
July 11, 2023