Preparation method of coarse denier non-crimp dumbbell-shaped full-dull polyester staple fiber

Abstract

The invention relates to a method for preparing a coarse denier non-crimp dumbbell-shaped full-dull polyester staple fiber, wherein the full-dull polyester slice is dried, melted by a screw extruder, spun by a dumbbell-shaped special-shaped hole spinneret, cooled by short-distance blowing with a ring blow tube, wound, and dropped into a barrel to obtain a raw fiber, and the raw fiber is subjected to the steps of post-spinning bundling, first-stage oil bath drawing, second-stage steam drawing, tense heat setting, stacking and oiling, and cutting to obtain a coarse denier non-crimp dumbbell-shaped full-dull polyester staple fiber; the dumbbell-shaped special-shaped hole spinneret is The diameter is 220mm, the dumbbell-shaped hole length is 2.2±0.025mm, the dumbbell-shaped hole points to the center of the spinneret at 15°, the number of holes is 208, each circle has 52 holes, a total of 4 circles, the circle radial center distance is 9mm, the shortest distance from the spinneret surface to the top row of air holes of the ring blowing tube is 30mm, the wind speed is 1.7-1.8m / s; the winding speed is 1050-1150m / min; the nozzle stretching multiple is 160-190 times. The present invention effectively solves the problem that the coarse denier non-curled dumbbell-shaped full-dull polyester staple fiber has high defects and is dispersed.

Description

Technical Field

[0001] The invention belongs to the technical field of polyester staple fiber preparation, and relates to a method for preparing coarse-denier non-curled dumbbell-shaped full-dull polyester staple fiber. Background Art

[0002] Coarse denier non-crimped dumbbell-shaped full-dull polyester (PET) staple fiber is a non-crimped full-dull polyester staple fiber with a nominal linear density of 10D-12D, a nominal length generally not less than 76mm, and a dumbbell-shaped cross-section. Users usually blend this fiber with wool and other materials to embellish the fabric. However, there is a problem with this type of fiber at present. Due to the coarse nominal linear density of the fiber, the high content of fiber matting agent, and the dumbbell-shaped micropores of the spinneret, the defect content in every 100 grams of fiber produced is as high as 100 mg and is dispersed. After the fiber is opened and dyed, the color of the defective fiber is significantly darker than that of the normal fiber, affecting the normal use of the fiber. Although some companies have tried to reduce the spinning temperature to solve the problem of high defect content and dispersion of coarse denier non-crimped dumbbell-shaped full-dull polyester (PET) staple fibers, the reduction of spinning temperature is limited. Exceeding a certain limit will lead to significant differences in the uniformity of cooling the original yarn, and the fiber defect content will not only not decrease, but will increase significantly. Some companies have tried to significantly increase the winding speed to shorten the coagulation area of ​​the original yarn and move it toward the spinneret, but the increase in winding speed is restricted by the equipment. When the winding speed exceeds a certain limit, the cooling air near the outer ring area of ​​the spinneret will be blown away by the tow. Most of them are oriented in the direction of the winding process, resulting in poor penetration of the spinning cooling air, and significantly poor cooling effect of the raw yarn near the inner circle of the spinneret. As a result, the fiber defect content cannot be effectively reduced. Some companies try to reduce the number of spinneret holes, but when the number of spinneret holes is reduced to a certain limit, in order to ensure that the linear density of the fiber meets certain requirements, the frequency of the metering pump needs to be reduced, which not only leads to a significant reduction in production efficiency, but also because the metering pump frequency is too low, the component pressure is also low, affecting the dumbbell-shaped cross-sectional shape of the raw yarn, etc. As a result, the problem of high fiber defect content cannot be fundamentally solved. Summary of the invention

[0003] The purpose of the present invention is to solve the above problems existing in the prior art and to provide a method for preparing coarse denier non-crimped dumbbell-shaped full-dull polyester staple fibers.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a coarse denier non-crimp dumbbell-shaped full-dull polyester staple fiber, comprising drying full-dull polyester slices, melting with a screw extruder, spinning with a dumbbell-shaped special-shaped hole spinneret, short-distance blowing cooling with a ring blow tube, winding, and dropping into a barrel to obtain a raw yarn, and the raw yarn is subjected to the steps of post-spinning bundling, first-stage oil bath drawing, second-stage steam drawing, tense heat setting, stacking and oiling, and cutting to obtain a coarse denier non-crimp dumbbell-shaped full-dull polyester staple fiber;

[0006] The diameter of the dumbbell-shaped special-shaped hole spinneret is 220 mm. The dumbbell-shaped special-shaped hole is composed of dumbbell parts symmetrical at both ends and a flat shape in the middle. The diameter of the dumbbell part is 0.45±0.005 mm, the width of the flat gap is 0.2±0.005 mm, the dumbbell-shaped special-shaped hole is 2.2±0.025 mm long, the dumbbell-shaped special-shaped hole points to the center of the spinneret at 15°, the number of holes is 208, each circle has 52 holes, a total of 4 circles, the radial center distance of the circle is 9 mm, the shortest distance from the spinneret surface to the uppermost row of blowing holes of the ring blowing tube is 30 mm, and the wind speed is 1.7-1.8 m / s;

[0007] The winding speed is 1050-1150 m / min, preferably 1100 m / min;

[0008] The nozzle stretching ratio is 160 to 190 times;

[0009] The nominal linear density of the coarse denier non-crimped dumbbell-shaped full-dull polyester staple fiber is 10D-12D, the linear density deviation rate is ±5.0%, and the fiber defect content does not exceed 25mg / 100g.

[0010] The nominal linear density of the fiber prepared by the present invention is 10D-12D, and the cross section of the fiber is a dumbbell-shaped cross section. The heat brought out by the melt stream ejected from the spinneret hole per unit time is significantly increased. Since a high content of titanium dioxide particles is added to the melt, the fluidity of the melt is significantly increased, the solidification zone of the precursor is increased, and the fiber defect content will increase by hundreds and be dispersed when the precursor is later drawn. For this reason, the experiment adopts the following methods: a small number of holes in the spinneret (to improve the penetration of the cooling air into the precursor and lay the foundation for the uniformity of cooling a single precursor), a short blowing distance (to quickly and evenly cool each precursor and shorten the solidification zone of each precursor), and a relatively The combined design of low spinning temperature (while ensuring the melt can flow, reducing the heat of the melt stream when it is ejected from the spinneret), higher wind speed (increasing the wind penetration, and reaching a balance when the wind reaches the center of the spinneret (that is, at the center of the spinneret, the wind from the circumferential direction is basically offset to prevent the original yarn from shaking significantly), and higher winding speed (moving and shortening the solidification area of ​​the original yarn toward the spinneret surface, and transferring the heat near the spinneret to the winding process with the airflow) and higher nozzle stretching multiple (increasing the uniformity of the density of each original yarn) improves the uniformity of cooling the original yarn and greatly reduces the occurrence of defects in the original yarn during post-drawing.

[0011] As the preferred technical solution:

[0012] As described above, a method for preparing a coarse denier non-curled dumbbell-shaped fully matte polyester staple fiber, the fully matte polyester chips have a melting point of 258-262° C., an intrinsic viscosity of 0.680±0.013 dl / g, and a titanium dioxide content of 2.42-2.48 wt %.

[0013] In the method for preparing a coarse denier non-crimped dumbbell-shaped fully matte polyester staple fiber as described above, the temperature of the screw extruder is: 273±3°C for zone one, 278±3°C for zone two, 283±4°C for zone three, 290±3°C for zone four, 283±3°C for zone five, 278±3°C for zone six, and 273±2°C for the filter, melt pipe and box.

[0014] In the method for preparing the coarse denier non-crimp dumbbell-shaped full-dull polyester staple fiber as described above, the moisture content of the full-dull polyester chips after drying is ≤40ppm.

[0015] As described above, a method for preparing a coarse denier non-curled dumbbell-shaped fully matte polyester staple fiber, the fully matte polyester chips are dried using a boiling dryer, and the process parameters are: pre-crystallization temperature 175±1°C, drying temperature 178±2°C, total drying cycle 4.5 hours, and dew point temperature ≤-80°C.

[0016] In the method for preparing a coarse denier non-crimped dumbbell-shaped fully dull polyester staple fiber as described above, the total post-spinning drafting multiple is 3.38-3.70, and the drafting tank temperature is 72±2°C.

[0017] In the method for preparing a coarse denier non-crimped dumbbell-shaped fully dull polyester staple fiber as described above, the first-stage oil bath drawing temperature of post-spinning is 72±2°C, and the second-stage steam drawing temperature is 100±2°C.

[0018] The method for preparing a coarse denier non-crimped dumbbell-shaped full-dull polyester staple fiber as described above has a tensile heat setting temperature of 175±2°C.

[0019] Beneficial effects:

[0020] The present invention significantly improves the cooling uniformity of dumbbell-shaped cross-section polyester raw fibers by systematically designing dumbbell-shaped special-shaped holes, hole radial circle distance, hole number and air blowing cooling short distance, and controlling the moisture content of fully matte polyester slices after drying and the nozzle stretching multiple at a higher spinning speed, so that the defect content of the prepared coarse denier (fiber nominal linear density 10D-12D) non-crimped dumbbell-shaped fully matte polyester (PET) staple fibers can be controlled, thereby solving the problem of high fiber defect content and dispersion. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0022] The testing method adopted by the present invention is as follows:

[0023] (1) Breaking strength: Tested using GB / T 14337 test method for tensile properties of chemical staple fibers;

[0024] (2) Elongation at break: tested using GB / T 14337 test method for tensile properties of chemical staple fibers;

[0025] (3) Fiber defects: Tested using Method A in GB / T 14339 Test method for defects of chemical staple fibers;

[0026] (4) Oil content: Tested using GB / T 6504 test method for oil content of chemical fibers;

[0027] (5) 180°C dry heat shrinkage: tested using FZ / T 50004 polyester staple fiber dry heat shrinkage test method.

[0028] Example 1

[0029] A method for preparing coarse denier non-crimped dumbbell-shaped full-dull polyester staple fiber (nominal linear density is 10D×88mm), the specific steps are as follows:

[0030] (1) Drying of raw materials;

[0031] After checking and cleaning the boiling dryer, the temperature of the first and second pre-crystallization zones were set to 175°C, the temperature of the drying zone was set to 178°C, the pre-crystallization fan was started, the compressed air pipeline of the drying tower and the dehumidification system of the compressed air were opened, and the corresponding steam pipeline valves were opened to increase the temperature. After reaching the temperature, the full-dull polyester chips (melting point of 260°C, characteristic viscosity of 0.687dl / g, titanium dioxide content of 2.45wt%) were manually pre-crystallized. After the chips in the pre-crystallization bed were boiled, covered and crystallized, the chips began to fall into the drying tower, and then the manual control was switched to the automatic control. The total drying cycle was 4.5 hours, the dew point temperature was -84°C, and the chips were dried until the moisture content of the chips was 36ppm;

[0032] (2) Preparation of raw silk;

[0033] The fully matt polyester chips dried in step (1) are melted by a screw extruder, spun by a dumbbell-shaped spinneret, cooled by short-distance blowing by a ring blow tube, wound, and dropped into a barrel to obtain a raw yarn with a linear density of 34.2D;

[0034] Among them, the metering pump frequency is 36.56Hz, the screw extruder temperature is: zone 1 272℃, zone 2 277℃, zone 3 282℃, zone 4 290℃, zone 5 282℃, zone 6 277℃, filter, melt pipe and box 273℃;

[0035] The diameter of the dumbbell-shaped special-shaped hole spinneret is 220mm. The dumbbell-shaped special-shaped hole is composed of dumbbell parts symmetrical at both ends and a flat shape in the middle. The diameter of the dumbbell part is 0.45mm, the width of the flat gap is 0.2mm, the dumbbell-shaped special-shaped hole is 2.2mm long, and the dumbbell-shaped special-shaped hole points to the center of the spinneret at 15°. There are 208 holes, 52 holes per circle, a total of 4 circles, and the radial center distance of the circle is 9mm; the shortest distance from the spinneret surface to the top row of blowing holes of the ring blowing tube is 30mm; the wind speed is 1.7m / s; the winding speed is 1100m / min; the nozzle stretching multiple is 187 times;

[0036] (3) Fiber preparation;

[0037] The raw silk of step (2) is subjected to the steps of post-spinning bundling, first-stage oil bath drawing, second-stage steam drawing, tensile heat setting, filament stacking and oiling, and cutting to obtain a coarse denier non-crimp dumbbell-shaped full-dull polyester staple fiber;

[0038] Among them, the first-stage oil bath drawing temperature of post-spinning is 72℃, the second-stage steam drawing temperature is 100℃, the tensile heat setting temperature is 175℃, and the total post-spinning drawing multiple is 3.62;

[0039] The obtained coarse denier non-curled dumbbell-shaped full-dull polyester staple fiber has a linear density of 10.45D, a linear density deviation rate of 4.5%, a breaking strength of 3.93cN / dtex, an elongation at break of 34.9%, a fiber defect content of 6.2mg / 100g, an oil content of 0.24%, and a 180-degree dry heat shrinkage rate of 5.0%.

[0040] After the fibers were opened, they were dyed with disperse dyes at 130°C. The dyed fibers were washed with water and dried, and there was no obvious difference in the fiber color.

[0041] Comparative Example 1

[0042] A method for preparing coarse denier non-crimped dumbbell-shaped full-dull polyester staple fibers (nominal linear density of 10D×88mm), which is basically the same as Example 1, except that in step (2), the metering pump frequency is adjusted from 36.56 Hz to 44.95 Hz, the number of holes of the dumbbell-shaped spinneret is adjusted from 208 holes to 288 holes, the winding speed is adjusted from 1100 m / min to 1000 m / min, and the distance between the spinneret surface and the uppermost row of blowing holes of the ring blowing cylinder is adjusted from 30 mm to 50 mm.

[0043] The linear density of the prepared raw silk is 33.5D, the linear density of the coarse denier non-curled dumbbell-shaped full-dull polyester staple fiber is 10.36D, the linear density deviation rate is 3.6%, the breaking strength is 3.97cN / dtex, the breaking elongation is 38.9%, and the fiber defect content is 200mg / 100g (and the defects are dispersed defects, even if the draft ratio is greatly increased, the fiber defect content remains high).

[0044] After the fibers were opened, they were dyed with disperse dyes at 130°C. The dyed fibers were washed with water and dried. The color of the fibers containing defects was obviously darker than that of normal fibers, and the fibers containing defects were obviously harder.

[0045] Example 2

[0046] A method for preparing coarse denier non-crimped dumbbell-shaped full-dull polyester staple fiber (nominal linear density is 12D×88mm), the specific steps are as follows:

[0047] (1) Drying of raw materials;

[0048] After checking and cleaning the boiling dryer, the temperature of the first and second pre-crystallization zones were set to 175°C, and the temperature of the drying zone was set to 178°C. The pre-crystallization fan was started, the compressed air pipeline of the drying tower and the dehumidification system of the compressed air were opened, and the corresponding steam pipeline valves were opened to increase the temperature. After reaching the temperature, the full-dull polyester chips (melting point of 262°C, characteristic viscosity of 0.692dl / g, titanium dioxide content of 2.46wt%) were manually pre-crystallized. After the chips in the pre-crystallization bed were boiled, covered and crystallized, the chips began to fall into the drying tower, and then the manual control was switched to the automatic control. The total drying cycle was 4.5 hours, the dew point temperature was -84°C, and the chips were dried until the moisture content of the chips was 35ppm.

[0049] (2) Preparation of raw silk;

[0050] The fully matt polyester chips dried in step (1) are melted by a screw extruder, spun by a dumbbell-shaped spinneret, cooled by short-distance blowing by a ring blow tube, wound, and dropped into a barrel to obtain a raw yarn with a linear density of 38.7D;

[0051] Among them, the metering pump frequency is 41.30Hz, the screw extruder temperature is: zone 1 272℃, zone 2 277℃, zone 3 282℃, zone 4 290℃, zone 5 282℃, zone 6 277℃, filter, melt pipe and box 272℃;

[0052] The diameter of the dumbbell-shaped special-shaped hole spinneret is 220mm. The dumbbell-shaped special-shaped hole is composed of dumbbell parts symmetrical at both ends and a flat shape in the middle. The diameter of the dumbbell part is 0.45mm, the width of the flat gap is 0.2mm, the dumbbell-shaped special-shaped hole is 2.2mm long, and the dumbbell-shaped special-shaped hole points to the center of the spinneret at 15°. There are 208 holes, 52 holes per circle, a total of 4 circles, and the radial center distance of the circle is 9mm; the shortest distance from the spinneret surface to the top row of blowing holes of the ring blowing tube is 30mm; the wind speed is 1.8m / s; the winding speed is 1100m / min; the nozzle stretching multiple is 167 times;

[0053] (3) Fiber preparation;

[0054] The raw silk of step (2) is subjected to the steps of post-spinning bundling, first-stage oil bath drawing, second-stage steam drawing, tensile heat setting, filament stacking and oiling, and cutting to obtain a coarse denier non-crimp dumbbell-shaped full-dull polyester staple fiber;

[0055] Among them, the first-stage oil bath drawing temperature of post-spinning is 72℃, the second-stage steam drawing temperature is 100℃, the tensile heat setting temperature is 175℃, and the total post-spinning drawing multiple is 3.67;

[0056] The obtained coarse denier non-curled dumbbell-shaped full-dull polyester staple fiber has a linear density of 12.08D, a linear density deviation rate of 0.67%, a breaking strength of 4.03cN / dtex, an elongation at break of 4.03%, a fiber defect content of 12mg / 100g, an oil content of 0.27%, and a 180-degree dry heat shrinkage rate of 7.0%.

[0057] After the fibers were opened, they were dyed with disperse dyes at 130°C. The dyed fibers were washed with water and dried, and there was no obvious difference in the fiber color.

[0058] Comparative Example 2

[0059] A method for preparing coarse denier non-crimped dumbbell-shaped full-dull polyester staple fibers (nominal linear density of 12D×88mm) is basically the same as that in Example 2, except that the distance between the spinneret surface and the uppermost row of blowing holes of the annular blowing cylinder in step (2) is adjusted from 30mm to 50mm.

[0060] The obtained coarse denier non-crimp dumbbell-shaped full-dull polyester staple fiber has a linear density of 12.1D, a linear density deviation rate of 0.83%, and a fiber defect content of 110 mg / 100 g.

[0061] After the fibers are opened, they are dyed with disperse dyes at 130°C. The dyed fibers are washed with water and dried. There are obvious differences in the colors of the fibers, and the fibers with obviously darker colors contain defects.

[0062] Comparative Example 3

[0063] A method for preparing coarse denier non-crimped dumbbell-shaped full-dull polyester staple fibers (nominal linear density of 12D×88mm), which is basically the same as Example 2, except that the metering pump frequency in step (2) is adjusted from 41.30Hz to 52.00Hz, the number of holes of the special-shaped spinneret is changed from 208 holes to 288 holes, the winding speed is adjusted from 1100m / min to 1000m / min, and the distance between the spinneret surface and the uppermost row of blowing holes of the ring blowing cylinder is adjusted to 40mm.

[0064] The obtained raw yarn linear density is 38.7D, the linear density of the coarse denier non-curled dumbbell-shaped full-dull polyester staple fiber is 12D, the linear density deviation rate is 0%, and the fiber defect content is 300mg / 100g (even if the spinning draft multiple is adjusted, the fiber defect content remains basically unchanged).

[0065] After the fibers are opened, they are dyed with disperse dyes at 130°C. The dyed fibers are washed with water and dried. The color depth of the fibers is very obvious. The fibers with obviously darker colors contain defects, and the defects in the fibers appear as powder when squeezed by hand.

Claims

1. A method for preparing coarse denier non-crimped dumbbell-shaped full-dull polyester staple fibers, characterized in that: The full-dull polyester chips are dried, melted by a screw extruder, spun by a dumbbell-shaped special-shaped hole spinneret, cooled by short-distance blowing with a ring blow tube, wound, and dropped into a barrel to obtain raw yarn, and the raw yarn is subjected to the following steps: post-spinning bundling, first-stage oil bath drawing, second-stage steam drawing, tense heat setting, stacking and oiling, and cutting to obtain coarse denier non-crimp dumbbell-shaped full-dull polyester staple fibers; The diameter of the dumbbell-shaped special-shaped hole spinneret is 220 mm. The dumbbell-shaped special-shaped hole is composed of dumbbell parts symmetrical at both ends and a flat shape in the middle. The diameter of the dumbbell part is 0.45±0.005 mm, the width of the flat gap is 0.2±0.005 mm, the dumbbell-shaped special-shaped hole is 2.2±0.025 mm long, the dumbbell-shaped special-shaped hole points to the center of the spinneret at 15°, the number of holes is 208, each circle has 52 holes, a total of 4 circles, the radial center distance of the circle is 9 mm, the shortest distance from the spinneret surface to the uppermost row of blowing holes of the ring blowing tube is 30 mm, and the wind speed is 1.7-1.8 m / s; Winding speed is 1050~1150m / min; The nozzle stretching ratio is 160 to 190 times; The box temperature is 273±2℃; The moisture content of the fully matte polyester chips after drying is ≤40ppm; The nominal linear density of the coarse denier non-crimped dumbbell-shaped full-dull polyester staple fiber is 10D-12D, the linear density deviation rate is ±5.0%, and the fiber defect content does not exceed 25mg / 100g.

2. The method for preparing a coarse denier non-crimped dumbbell-shaped full-dull polyester staple fiber according to claim 1, characterized in that: The melting point of the full-dull polyester chips is 258-262° C., the intrinsic viscosity is 0.680±0.013 dl / g, and the titanium dioxide content in the full-dull polyester chips is 2.42-2.48 wt %.

3. The method for preparing a coarse denier non-crimped dumbbell-shaped full-dull polyester staple fiber according to claim 1, characterized in that: The temperature of the screw extruder is: zone 1 273±3℃, zone 2 278±3℃, zone 3 283±4℃, zone 4 290±3℃, zone 5 283±3℃, zone 6 278±3℃, filter and melt pipe 273±2℃.

4. The method for preparing a coarse denier non-crimped dumbbell-shaped full-dull polyester staple fiber according to claim 1, characterized in that: The full matt polyester chips are dried using a boiling dryer with the following process parameters: pre-crystallization temperature 175±1℃, drying temperature 178±2℃, total drying cycle 4.5 hours, dew point temperature ≤-80℃.

5. The method for preparing a coarse denier non-crimped dumbbell-shaped full-dull polyester staple fiber according to claim 1, characterized in that: The total post-spinning drafting multiple is 3.38-3.70, and the drafting tank temperature is 72±2℃.

6. The method for preparing a thick denier non-crimped dumbbell-shaped full-dull polyester staple fiber according to claim 1, characterized in that: The first stage oil bath drawing temperature of post-spinning is 72±2℃, and the second stage steam drawing temperature is 100±2℃.

7. The method for preparing a coarse denier non-crimped dumbbell-shaped full-dull polyester staple fiber according to claim 1, characterized in that: The tensile heat setting temperature is 175±2℃.