A preparation device and preparation method of polyester industrial yarn for airbags

Abstract

The present invention belongs to the field of spinning technology and relates to a preparation device and preparation method of polyester industrial yarn for airbags. The preparation device includes a spinneret, a cooling air duct, four wire-feeding drums, a cross-circular non-porous plate, a cross-circular porous plate, a suction drum, an annular non-porous plate, an annular porous plate, an air supply duct and a suction duct; the four wire-feeding drums, the upper section of the cooling air duct, the cross-circular non-porous plate, and the cross-circular porous plate together form an air supply chamber; the inner wall of the middle section of the cooling air duct is provided with a plurality of grooves, and the suction drum, the annular non-porous plate, the annular porous plate, and the lower section of the cooling air duct together form a suction chamber; the suction duct is arranged horizontally and is connected to the suction chamber. The preparation method adopts the preparation device as described above. The polyester industrial yarn obtained by the preparation method of the present invention takes into account flatness, high breaking strength, high breaking elongation and high yarn uniformity, improves the softness of the airbag fabric, and has important application value in the field of automobile safety.

Description

Technical Field

[0001] The invention belongs to the technical field of spinning, and relates to a device and a method for preparing polyester industrial yarn for airbags. Background Art

[0002] In recent years, with increased safety awareness, airbags have become widely recognized as a key component of automotive passive safety systems. In a collision, airbags work in conjunction with seatbelts to effectively mitigate impacts on the passenger's head, chest, and other areas, protecting them. As the number of airbags installed in vehicles increases, the demand for lightweight airbags is also growing.

[0003] Current automotive airbags are made of airbag fabric. To achieve pressure retention and low air permeability, the fabric typically needs to be coated with glue, which makes the airbag thicker and increases cost. According to the invention patent application with publication number CN105256597A, after calendering, the chemical fiber filaments in the airbag fabric adopt a flat structure with a unique "I"-shaped cross-section, which maintains airtightness and reduces the amount of glue applied by 38%. Therefore, the development of flat airbag yarn can not only ensure the airbag fabric has good airtightness, but also reduce the amount of glue applied, saving costs and making the automotive airbag more lightweight.

[0004] Polyester industrial yarn, with its high strength, holds significant application value in automotive airbags. Changing the fiber's cross-section from a round to a straight line reduces its rigidity while increasing its elongation at break and flexibility. However, polyester industrial yarn, typically 96F or 144F, contains many individual filaments per tow. The asymmetric straight line shape makes uniform cooling of the tow difficult.

[0005] In order to solve the problem of uneven cooling of a tow composed of flat filaments, a small amount of research has been conducted in the prior art.

[0006] For example, patent application CN104831382A discloses a method for producing glossy flat polyester filaments using side-blown cooling, with the side-blown airflow direction parallel to the spinneret blade extension direction. However, during the spinning process, due to the large number of filaments and low spinning tension of the nascent fibers, the fibers, after exiting the spinneret, are affected by the airflow between the fibers and the external environment (such as the opening and closing of the side-blown spinning window and the movement of on-site workers), making it difficult to ensure that the fiber blade direction remains parallel to the cooling airflow direction during the cooling process. This results in the blowing direction being perpendicular to the fiber blade direction. Since the flat filaments have a large aspect ratio, the heat removed by the blowing direction parallel to the fiber blade direction is greater than that by the blowing direction perpendicular to the fiber blade direction. This results in uneven cooling between the flat filaments, resulting in a reduced elongation at break of the produced fibers, which cannot meet the softness requirements of airbag fabrics. Furthermore, subsequent stretching is prone to uneven stretching, resulting in poor fiber evenness and an increase in broken ends.

[0007] For example, patent application CN106400167A discloses a porous ultrafine denier flat yarn and its preparation method. The arrangement of spinneret holes is changed from a circular arrangement to an elliptical arrangement. For a given effective spinneret area, the number of layers of elliptical holes is smaller than that of a circular arrangement, while the number of holes in the elliptical arrangement is greater than that of a circular arrangement. Cooling is achieved by blowing through the spinning stream with an annular airflow. However, the direction of this annular airflow is not always parallel to the direction of the fiber blades, making uniform cooling impossible. The resulting fiber has a reduced elongation at break, failing to meet the softness requirements of airbag fabrics. Furthermore, the fiber is prone to uneven stretching during stretching, resulting in poor yarn uniformity.

[0008] Therefore, it is necessary to develop a preparation device and a manufacturing method for polyester industrial yarn for airbags that can take into account flatness, high breaking strength, high breaking elongation and high yarn uniformity. Summary of the Invention

[0009] The purpose of the present invention is to solve the above problems existing in the prior art and to provide a device and method for preparing polyester industrial yarn for airbags.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0011] A device for preparing polyester industrial yarn for airbags, comprising a spinneret, a cooling air cylinder, four wire feeding cylinders, a cross-circular non-porous plate, a cross-circular porous plate, a suction cylinder, an annular non-porous plate, an annular porous plate, an air supply duct, and a suction duct;

[0012] The cooling duct is open at both ends, has no holes in the wall, is arranged vertically, is cylindrical, and is divided into three sections: upper, middle, and lower.

[0013] The four wire-moving cylinders are open at both ends, with no holes in the cylinder wall. They are vertically arranged in the upper section of the cooling air cylinder. The upper ends of the four wire-moving cylinders are flush with the upper end of the upper section of the cooling air cylinder and the five are connected by a cross-circular non-porous plate. The lower ends of the four wire-moving cylinders are flush with the lower end of the upper section of the cooling air cylinder and the five are connected by a cross-circular porous plate. The cross-circular ring is composed of a circular ring and a cross in it. The four wire-moving cylinders, the upper section of the cooling air cylinder, the cross-circular non-porous plate, and the cross-circular porous plate together form an air supply cavity.

[0014] The inner wall of the middle section of the cooling duct is provided with a plurality of grooves for suppressing the separation of the boundary layer from the cooling duct. The boundary layer is a fluid layer formed due to viscosity when the cooling air flows through the inner wall surface of the cooling duct.

[0015] The suction cylinder is open at both ends, has no holes in the cylinder wall, is vertically arranged in the lower section of the cooling air cylinder and is coaxial therewith, the upper end of the suction cylinder is flush with the upper end of the lower section of the cooling air cylinder and the two are connected by an annular porous plate, the lower end of the suction cylinder is flush with the lower end of the lower section of the cooling air cylinder and the two are connected by an annular non-porous plate, and the suction cylinder, the annular non-porous plate, the annular porous plate, and the lower section of the cooling air cylinder together form a suction chamber;

[0016] The air supply duct is arranged horizontally and communicated with the air supply cavity; the suction duct is arranged horizontally and communicated with the suction cavity;

[0017] The spinneret holes are distributed in four areas, and the four areas are located directly above the hollow parts of the four wire drums.

[0018] The principles of the present invention are as follows:

[0019] Since the cross-section of the flat yarn is non-circularly symmetrical, if the cooling method of ring blowing or side blowing vertical air is adopted in the existing technology, the ideal state is that the blowing direction is parallel to the direction of the fiber blades (such as the design of the patent application with patent publication number CN104831382A), which can take away the heat of the yarn bundle to the greatest extent and achieve a cooling effect. Without considering the impact of the environment, it is necessary to increase the spinning tension, which will cause the following problems: 1. When the spinning tension is increased, the orientation and crystallization degree of the primary fiber are large, and the residual elongation at break is low, which is not conducive to improving the fiber elongation at break and affects the softness of the airbag fabric; 2. When the spinning tension is high, the surface tension of the melt flow increases, which will make the cross-section of the flat yarn tend to become circular and the degree of special shape is reduced; 3. Excessive tension will cause breakage and hairy yarns, and stable production cannot be achieved. Existing technologies mainly shorten the length of the windless zone to achieve rapid cooling and maintain the shape, and then extend the cooling length to achieve the purpose of sufficient cooling. Compared with circular cross-section fibers, flat yarns have a larger specific surface area. Extending the cooling zone length increases the frictional resistance between the yarn bundle and the air, and increases the spinning tension, which is not conducive to improving the fiber's elongation at break.

[0020] The present invention arranges the structure of the cooling duct, the position of the air supply duct, the connection method of the air supply duct and the cooling duct, etc., so that the flow direction of the cooling air in the cooling duct is the same as the running direction of the yarn bundle, and the yarn bundle is divided into four areas for synchronous cooling through the "field"-shaped cavity structure of the wire drum. The advantages are: 1. The cross-section of the flat yarn has the characteristic of non-circular symmetry. The flow direction of the cooling air is perpendicular to the direction of the flat yarn blades and parallel to the blade direction, and the heat of the yarn bundle taken away is different, resulting in different cooling uniformity of the single yarn. If the cooling air is used in the same direction as the running direction of the yarn bundle, this problem does not exist, and the problem of uniform cooling of the flat yarn is solved; 2. The yarn bundle is divided into four areas for synchronous cooling, which reduces the problem of uneven cooling of the inner and outer circles of the multi-porous polyester filament and the spinneret; 3. The flat yarn has the characteristic of large specific surface area. The use of cooling air parallel to the running direction of the yarn bundle can reduce the speed difference between the air and the yarn bundle compared to the traditional vertical blowing method of ring blowing and side blowing, effectively reduce the friction of the air, and thus reduce the spinning tension. During the extrusion of the spinning melt to form nascent fibers, spinning tension increases the orientation of polymer molecules and induces stress-induced crystallization. Reducing the spinning tension can reduce the degree of molecular orientation and the crystallinity of the nascent fibers. The nascent fibers have a high residual elongation. Subsequent stretching by hot rollers, at the same stretch ratio, not only maintains a certain strength but also a high elongation, meeting the softness requirements of airbag fabrics.

[0021] However, such an arrangement is prone to excessive turbulence and flow separation in the cooling duct, which has an adverse effect on the uniformity of the tow. To avoid excessive turbulence and flow separation, the present invention has also made the following improvements:

[0022] ① Set grooves on the inner wall of the cooling duct;

[0023] The inner wall surface of the cooling duct in the prior art is a smooth plane. When the cooling air flows through the cooling duct, the viscosity of the air flow generates friction with the wall surface of the cooling duct. The cooling air contacting the wall surface of the cooling duct slows down, forming a very thin boundary layer. The flow velocity outside the boundary layer changes very little, while the flow velocity inside changes dramatically. In the cross-sectional direction of the cooling duct, the flow velocity on both sides close to the wall surface of the cooling duct is relatively small, and the flow velocity in the middle part is consistent with the incoming flow velocity and does not change much. Due to the large velocity gradient inside the boundary layer, the kinetic energy of the flow is lost due to the action of the viscosity force, and the flow velocity of the inner layer will become slower and slower. According to Bernoulli's theorem, the flow velocity becomes slower and the pressure becomes higher. As the flow increases, the flow in the boundary layer becomes more and more difficult, and finally separates from the wall surface of the cooling duct, generating a huge separation vortex. The generation of the vortex makes the cooling air become chaotic, which will disturb the filament bundle and affect the cooling of the filament bundle.

[0024] The present invention provides grooves on the inner wall of the cooling duct. The cooling air can generate small refracted flows at the grooves, avoiding the generation of huge separation vortices, thereby suppressing the separation of the boundary layer and avoiding large separation vortices. It is like coating the wall of the cooling duct with an "oil film". The flow resistance of the air flow outside the "oil film" is reduced, and the overall flow velocity on the cross section of the cooling duct becomes more stable and uniform, so that the filament bundle is cooled more evenly and the uniformity of the filament bundle is improved.

[0025] ② Set up a suction pipe at the end of the tow cooling;

[0026] At the outlet of the cylindrical cooling duct, the cooling air will have a reverse flow at the outlet of the cooling duct due to the sudden increase in the air flow channel (the cooling air is not bound by the cooling duct), the flow rate will decrease, and the pressure will increase, causing disturbance to the filament bundle; although the filament bundle has been cooled and solidified at this time, the disturbance of the filament bundle will be transmitted upward, which is not conducive to improving the uniformity of the filament bundle; the present invention sets a suction duct at the end position of the filament bundle cooling, and adjusts the suction force of the suction duct to keep the cooling air in a stable flow state, reduce the disturbance of the filament bundle, and thus improve the uniformity of the filament bundle.

[0027] As the preferred technical solution:

[0028] As described above, in a device for preparing polyester industrial yarn for airbags, the interior of the circular ring is divided into four equal parts in a cross shape; the cross-sections at each position of the four wire drums are fan-shaped and have the same size; the spinneret holes on the spinneret are rectangular with an aspect ratio of 7.1-10:1.

[0029] In the above-mentioned device for preparing polyester industrial yarn for airbags, the grooves are circular pit grooves arranged in a staggered lattice structure; the diameter of the circular pit grooves is 3-4 mm, the groove depth is 2-2.5 mm, and the center distance between any two adjacent circular pits is 9-10 mm.

[0030] The apparatus for preparing polyester industrial yarn for airbags as described above has non-circular grooves divided into multiple groups, wherein the non-circular grooves in the same group are distributed along the middle section of the cooling duct at a circumferential spacing of 4-6 mm, and the non-circular grooves in different groups are distributed along the middle section of the cooling duct at an axial spacing of 9-10 mm.

[0031] The non-circular groove gradually decreases in size from the groove opening to the groove bottom, the groove opening is oblong, the length of the oblong is 9-20 mm and the width of the oblong is 3-4 mm, the groove bottom is a line segment or a rectangle, and the groove depth is 2-2.5 mm;

[0032] When the groove bottom is rectangular, the angle θ between the groove wall and the central axis of the non-circular pit is 20-30°;

[0033] For the same non-circular pit groove, the short symmetry axis of the oblong, the perpendicular bisector of the line segment, and the short symmetry axis of the rectangle are all parallel to the axial direction of the cooling duct, and the straight line where the center of the oblong and the midpoint of the line segment or the center of the rectangle are located is perpendicular to and intersects with the central axis of the cooling duct.

[0034] In the above-mentioned device for preparing polyester industrial yarn for airbags, the inner diameter of the cooling air duct is 100-200 mm, the length of the upper section is 110-150 mm, the length of the middle section is 1000-1200 mm, and the length of the lower section is 110-150 mm.

[0035] In the above-mentioned device for preparing polyester industrial yarn for airbags, the outer diameter of the wire drum is 40-60 mm smaller than the inner diameter of the cooling air drum.

[0036] In the above-mentioned device for preparing polyester industrial yarn for airbags, the outer diameter of the suction cylinder is 40-60 mm smaller than the inner diameter of the cooling air cylinder.

[0037] In the above-mentioned device for preparing polyester industrial yarn for airbags, the inner diameter of the air supply duct is 100-120 mm, and the inner diameter of the suction duct is 100-120 mm.

[0038] The device for preparing polyester industrial yarn for airbags as described above also includes a spinning box, which is located above the cooling air duct, with a slow cooling zone and a windless zone between them, and the slow cooling zone is located above the windless zone.

[0039] In the above-mentioned device for preparing polyester industrial yarn for airbags, the height of the slow cooling zone is 95-105 mm; the height of the windless zone is 45-55 mm.

[0040] The device for preparing polyester industrial yarn for airbags as described above further includes a spinning tunnel, which is located below the cooling air cylinder and connected thereto.

[0041] In the above-mentioned device for preparing polyester industrial yarn for airbags, the length of the spinning tunnel is 600-700 mm.

[0042] The present invention also provides a method for preparing polyester industrial yarn for airbags, which uses the device for preparing polyester industrial yarn for airbags as described in any one of the above items.

[0043] As the preferred technical solution:

[0044] The spinning process of the polyester industrial yarn for airbags is as follows: polyester melt is extruded through a spinneret → cooled in a slow cooling zone → cooled in a windless zone → cooled in a cooling duct → oiled → stretched by six pairs of hot rollers → shaped → interlaced → wound;

[0045] The spinning process parameters include: ambient temperature 35-40℃; spinning temperature 291-310℃; slow cooling zone temperature 290-320℃; cooling air temperature 30-35℃; cooling air speed 0.5-1.0m / s; suction force of the suction pipe ≤0.2Pa; speed of the first pair of hot rollers 430-560m / min, temperature 60-70℃; speed of the second pair of hot rollers 450-580m / min, temperature 90-100℃; speed of the third pair of hot rollers 1850-2260m / min, temperature 123-135℃; speed of the fourth pair of hot rollers 2650-3600m / min, temperature 210-250 ℃; speed of the fifth pair of hot rollers 2580-3620m / min, temperature 210-250℃; speed of the sixth pair of hot rollers 2380-3420m / min, temperature 180-220℃; total stretching ratio 5.52-6.38, primary stretching ratio 3.70-4.22, secondary stretching ratio 1.39-1.71, total stretching ratio = speed of the fourth pair of hot rollers / speed of the second pair of hot rollers, primary stretching ratio = speed of the third pair of hot rollers / speed of the second pair of hot rollers, secondary stretching ratio = speed of the fourth pair of hot rollers / speed of the third pair of hot rollers; winding speed 2550-3610m / min; spinning tension 60-80cN;

[0046] The linear density of polyester industrial yarn for airbags is 420-600dtex, the number of holes is 96-144F, the breaking strength is ≥7.6cN / dtex, the elongation at break is 30±2%, the CV value of yarn unevenness is ≤1%, the dry heat shrinkage is ≤4.15%, the yarn degradation rate is ≤1.12%, and the fiber flatness is 3.1-4.2.

[0047] Beneficial effects:

[0048] (1) The preparation device of the present invention makes the cooling air flow direction in the cooling air duct the same as the running direction of the filament bundle, and divides the filament bundle into four areas through the wire drum for synchronous cooling, thereby solving the problem of uneven cooling of the flat fiber. The prepared flat fiber not only maintains a high breaking strength, but also maintains a high breaking elongation, thereby improving the softness of the airbag fabric and meeting the softness requirements of the airbag fabric.

[0049] (2) The preparation device of the present invention is provided with grooves on the inner wall of the cooling air duct to reduce the adhesion of the cooling air to the wall, and a suction pipe is provided at the end position of the cooling of the filament bundle to keep the cooling air in a stable state at all times. Finally, the disturbance of the filament bundle is avoided by the grooves and the suction pipe, thereby improving the uniformity of the filament bundle.

[0050] (3) The preparation method of the present invention reduces the amount of glue applied, saves costs, and meets the demand for lightweight airbag fabrics. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a structural schematic diagram of the preparation device of the present invention;

[0052] Figure 2 1. It is a bottom view schematic diagram of the wire-moving drum of the preparation device of the present invention;

[0053] Figure 3 2. It is a schematic front view of the wire-traveling drum of the preparation device of the present invention;

[0054] Figure 4 It is a partial schematic diagram of the air flow at the inner wall surface of the cooling duct of the preparation device of the present invention (circular pit groove);

[0055] Figure 5 This is a partial schematic diagram of the air flow at the inner wall of the cooling duct of the preparation device of the present invention (non-circular pit groove);

[0056] Figure 6 It is a combined schematic diagram of the front view and the top view of the non-circular pit groove (V-shaped groove) on the inner wall of the cooling air duct of the preparation device of the present invention;

[0057] Figure 7 It is a combined schematic diagram of the front view and the top view of the non-circular pit groove (inverted equal-height trapezoidal groove) on the inner wall of the cooling air duct of the preparation device of the present invention;

[0058] Figure 8 This is a partial schematic diagram of the air flow at the outlet of the cooling duct of Comparative Example 1A;

[0059] Figure 9 This is a partial schematic diagram of the air flow at the inner wall of the cooling duct of Comparative Example 2A;

[0060] Figure 10 3A is a schematic structural diagram of the cooling duct;

[0061] In the figure, 1 is the spinning box, 2 is the slow cooling zone, 3 is the windless zone, 4 is the wire drum, 5 is the cooling air, 6 is the air supply duct, 7 is the suction duct, 8 is the suction cylinder, 9 is the filament bundle, 10 is the cooling air cylinder, 11 is the spinning tunnel, 12 is the reverse airflow, 13 is the circular pit groove, 14 is the circular pit groove refraction flow, 15 is the non-circular pit groove, and 16 is the non-circular pit groove refraction flow. DETAILED DESCRIPTION

[0062] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, 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 equally within the scope limited by the appended claims of the application.

[0063] The following are the test methods for the relevant performance indicators in each embodiment and comparative example:

[0064] (1) Linear density: The test was conducted using a YG086 length measuring instrument in accordance with GB / T 14343-2008 “Test method for linear density of chemical fiber filaments”.

[0065] (2) Hole number: In chemical fiber production, "hole number" often refers to the number of spinneret holes, that is, how many single filaments a fiber is composed of. The SpinTrak spinneret detector from Aspex Corporation of the United States is used to detect the hole number.

[0066] (3) Breaking strength: The test was carried out using a YG023B-Ⅱ fully automatic single yarn strength tester in accordance with GB / T 14344-2022 “Test method for tensile properties of chemical fiber filaments”.

[0067] (4) Elongation at break: The test was conducted using a YG023B-Ⅱ fully automatic single yarn strength tester in accordance with GB / T 14344-2022 “Test method for tensile properties of chemical fiber filaments”.

[0068] (5) CV value of yarn unevenness: The test was conducted using USTER TESTER 5 yarn evenness meter in accordance with GB / T 14346-2015 “Test method for yarn unevenness of chemical filament yarns - Capacitance method”.

[0069] (6) Dry heat shrinkage: The test was conducted using a TST510 / 250 dry heat shrinkage tester in accordance with GB / T 16604-2017 Polyester Industrial Filament.

[0070] (7) Downgrade rate of wool yarn: refer to the specific inspection method of appearance requirements of GB / T 16604-2017 "Polyester Industrial Filament", count the number of downgraded wool yarn cakes and the number of full roll yarn cakes in one day, and the percentage of downgraded wool yarn cakes to the number of full roll yarn cakes is the downgrade rate of wool yarn.

[0071] (8) Fiber flatness (flatness of monofilament): According to FZ / T 50002-2013 "Test method for chemical fiber profile", first measure the cross-section of the fiber under a microscope, then measure the length and width of the fiber, and finally calculate the fiber flatness by dividing the length by the width.

[0072] Example 1A

[0073] like Figure 1-Figure 3The device for producing polyester industrial yarn for airbags shown in the figure consists of a spinning box 1, a spinneret, a cooling air cylinder 10, four wire drums 4, a cross-circular non-porous plate, a cross-circular porous plate, a suction cylinder 8, an annular non-porous plate, an annular porous plate, an air supply duct 6, a suction duct 7 and a spinning tunnel 11;

[0074] The cooling air duct 10 is open at both ends, has no holes in the wall, is vertically arranged, is cylindrical, and is divided into three sections: upper, middle, and lower.

[0075] Both ends of the four wire-walking cylinders 4 are open, and the cylinder walls have no holes. They are vertically arranged in the upper section of the cooling air cylinder 10. The upper ends of the four wire-walking cylinders 4 are flush with the upper end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular non-porous plate. The lower ends of the four wire-walking cylinders 4 are flush with the lower end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular porous plate. The cross-circular ring is composed of a circular ring and a cross in it. The cross divides the interior of the circular ring into four equal parts. The four wire-walking cylinders 4, the upper section of the cooling air cylinder 10, the cross-circular non-porous plate, and the cross-circular porous plate together form an air supply cavity; the cross sections of the four wire-walking cylinders 4 at various positions are all fan-shaped and have the same size;

[0076] like Figure 4 As shown, a plurality of grooves are provided on the inner wall of the middle section of the cooling air duct 10 for suppressing separation of the boundary layer from the cooling air duct 10. The boundary layer is a fluid layer formed due to viscosity when the cooling air 5 flows through the inner wall surface of the cooling air duct 10. The grooves are circular pit grooves 13 arranged in a staggered lattice structure. The cooling air 5 generates small circular pit groove refraction flows 14 at the circular pit grooves 13. The diameter of the circular pit grooves 13 is 3.5 mm, the groove depth is 2.2 mm, and the center distance between any two adjacent circular pits is 9 mm.

[0077] The suction cylinder 8 is open at both ends, and has no holes in the cylinder wall. It is vertically arranged in the lower section of the cooling air cylinder 10 and coaxial therewith. The upper end of the suction cylinder 8 is flush with the upper end of the lower section of the cooling air cylinder 10 and the two are connected by an annular porous plate. The lower end of the suction cylinder 8 is flush with the lower end of the lower section of the cooling air cylinder 10 and the two are connected by an annular non-porous plate. The suction cylinder 8, the annular non-porous plate, the annular porous plate, and the lower section of the cooling air cylinder 10 together form a suction chamber; the inner diameter of the cooling air cylinder 10 is 200 mm, the length of the upper section is 120 mm, the length of the middle section is 1200 mm, and the length of the lower section is 150 mm; the outer diameter of the wire drum 4 is 40 mm smaller than the inner diameter of the cooling air cylinder 10; the outer diameter of the suction cylinder 8 is 40 mm smaller than the inner diameter of the cooling air cylinder 10;

[0078] The air supply duct 6 is arranged horizontally and communicated with the air supply cavity; the suction duct 7 is arranged horizontally and communicated with the suction cavity; the inner diameter of the air supply duct 6 is 110 mm, and the inner diameter of the suction duct 7 is 110 mm;

[0079] The spinneret holes on the spinneret are rectangular with an aspect ratio of 8:1. The spinneret holes on the spinneret are distributed in four areas, and the four areas are respectively located directly above the hollow parts of the four wire barrels 4;

[0080] The spinning manifold 1 is located above the cooling air cylinder 10, with the slow cooling zone 2 and the windless zone 3 between them. The slow cooling zone 2 is located above the windless zone 3. The filament bundle 9 coming out of the spinning manifold 1 passes through the slow cooling zone 2 and the windless zone 3 and enters the wire drum 4. Then, the filament bundle 9 enters the cooling air cylinder 10. The flow direction of the cooling air 5 is parallel to the running direction of the filament bundle 9. The height of the slow cooling zone 2 is 100 mm; the height of the windless zone 3 is 55 mm.

[0081] The spinning shaft 11 is located below the cooling air cylinder 10 and connected thereto; the length of the spinning shaft 11 is 600 mm.

[0082] Example 1B

[0083] A method for preparing polyester industrial yarn for airbags, using the apparatus for preparing polyester industrial yarn for airbags as described in Example 1A above, wherein the spinning process comprises: extruding the polyester melt through a spinneret → cooling in a slow cooling zone → cooling in a windless zone → cooling in a cooling duct → oiling → stretching through six pairs of hot rollers → shaping → interlacing → winding;

[0084] The spinning process parameters are: ambient temperature 35℃; spinning temperature 290℃; slow cooling zone temperature 310℃; cooling air temperature 32℃; cooling air speed 0.7m / s; suction force of the suction pipe 0.1Pa; speed of the first pair of hot rollers 480m / min, temperature 60℃; speed of the second pair of hot rollers 495m / min, temperature 95℃; speed of the third pair of hot rollers 1980m / min, temperature 130℃; speed of the fourth pair of hot rollers 2885m / min, temperature 242℃; speed of the fifth pair of hot rollers 2740m / min, temperature 240℃; speed of the sixth pair of hot rollers 2550m / min, temperature 200℃; total stretching ratio 5.83, main stretching ratio 4, secondary stretching ratio 1.46; winding speed 2600m / min; spinning tension 60cN.

[0085] The prepared polyester industrial yarn for airbags has a linear density of 450dtex, a porosity of 96F, a breaking strength of 7.8cN / dtex, an elongation at break of 28%, a yarn unevenness CV value of 0.5%, a dry heat shrinkage rate of 4%, a hair degradation rate of 0.9%, and a fiber flatness of 3.1.

[0086] Comparative Example 1A

[0087] A production device for polyester industrial yarn is basically the same as that of Example 1A, except that no suction pipe is provided. Figure 8As shown, the cooling air 5 and the filament bundle 9 are both located in the cooling air cylinder 10 , and the cooling air 5 forms a reverse airflow 12 at the outlet of the cooling air cylinder 10 .

[0088] Comparative Example 1B

[0089] A method for preparing polyester industrial yarn is basically the same as that of Example 1B, except that a polyester industrial yarn preparation device provided in Comparative Example 1A is used.

[0090] The linear density of the polyester industrial yarn produced is 450dtex, the number of holes is 96F, the breaking strength is 7.8cN / dtex, the breaking elongation is 28%, the CV value of the yarn unevenness is 1.4%, the dry heat shrinkage rate is 4%, the hair degradation rate is 1.9%, and the fiber flatness is 3.1.

[0091] Comparing Comparative Example 1B with Example 1B, the linear density, breaking strength, elongation at break, and dry heat shrinkage of the polyester industrial yarn prepared in Comparative Example 1B showed no significant changes. However, the CV value of the yarn unevenness increased by 0.9%, and the lint degradation rate increased by 1.0%. This is because the cooling duct's outlet is not equipped with a suction duct, resulting in a reverse airflow at the cooling duct outlet. This causes airflow pressure fluctuations at the outlet of the cooling duct, causing disturbances in the yarn bundle. This causes filaments to "fight" with each other, and the filaments are then transported to the upper tow cooling zone, resulting in an increase in the CV value of the yarn unevenness and an increase in lint. This indicates that the suction duct has a significant impact on yarn uniformity and lint.

[0092] Comparative Example 2A

[0093] A polyester industrial yarn production device is basically the same as embodiment 1A, the only difference being that no circular pit grooves or non-circular pit grooves are provided. Figure 9 As shown, the cooling air 5 forms a reverse airflow 12 inside the cooling air cylinder 10 .

[0094] Comparative Example 2B

[0095] A method for preparing polyester industrial yarn is basically the same as that of Example 1B, except that a polyester industrial yarn preparation device provided in Comparative Example 2A is used.

[0096] The linear density of the produced polyester industrial yarn is 450dtex, the number of holes is 144F, the breaking strength is 7.5cN / dtex, the breaking elongation is 29%, the CV value of the yarn unevenness is 1.8%, the dry heat shrinkage rate is 4.12%, the yarn degradation rate is 1.3%, and the fiber flatness is 3.5.

[0097] Comparing Comparative Example 2B with Example 1B, the linear density, elongation at break, and dry heat shrinkage of the polyester industrial yarn produced in Comparative Example 2B showed no significant changes. However, the breaking strength decreased by 0.3 cN / dtex, the CV value of the strand unevenness increased by 1.3%, and the lint degradation rate increased by 0.4%. This is because the cooling duct's inner wall is not grooved, resulting in a reverse airflow within the duct and uneven cooling air velocity across the duct's cross section. This increases the difference in cooling levels between filament bundles, leading to uneven orientation and crystallization between filament bundle molecules, resulting in reduced breaking strength and increased CV value of the strand unevenness. Subsequently, lint appears at the same stretch ratio. This demonstrates that grooves have a significant impact on strand uniformity, breaking strength, and lint.

[0098] Comparative Example 3A

[0099] A preparation device for polyester industrial yarn, such as Figure 10 As shown, the filament bundle coming out of the spinning box 1 passes through the slow cooling zone 2 and the windless zone 3 and then enters the cooling air duct 10. After the cooling air 5 enters the cooling air duct 10 from the air supply duct 6, the flow direction of the cooling air 5 is perpendicular to the running direction of the filament bundle 9.

[0100] Comparative Example 3B

[0101] A method for preparing polyester industrial yarn is basically the same as that of Example 1B, except that a polyester industrial yarn preparation device provided in Comparative Example 3A is used.

[0102] The linear density of the produced polyester industrial yarn is 420dtex, the number of holes is 96F, the breaking strength is 8.3cN / dtex, the breaking elongation is 22%, the CV value of the yarn unevenness is 0.8%, the dry heat shrinkage rate is 4.3%, the hair degradation rate is 1.1%, and the fiber flatness is 4.2.

[0103] Comparing Comparative Example 3B with Example 1B, the linear density of the polyester industrial yarn produced in Comparative Example 3B did not change significantly, while the breaking strength increased by 0.5 cN / dtex, the elongation at break decreased by 6%, the CV value of the yarn unevenness increased by 0.3%, the dry heat shrinkage increased by 0.3%, and the lint degradation rate increased by 0.2%. This is because the cooling method, in which the cooling air flow direction is perpendicular to the yarn tow's travel direction, increases the tension on the tow, increasing the molecular orientation of the spun fibers. Subsequent stretching by heated rollers further increases the overall molecular chain orientation. Although the fiber's breaking strength increased, the elongation at break decreased, while the dry heat shrinkage increased. This demonstrates that the arrangement of the cooling air flow direction and the yarn tow's travel direction has a significant impact on the elongation at break and dry heat shrinkage.

[0104] Example 2A

[0105] like Figure 1-Figure 3The device for producing polyester industrial yarn for airbags shown in the figure consists of a spinning box 1, a spinneret, a cooling air cylinder 10, four wire drums 4, a cross-circular non-porous plate, a cross-circular porous plate, a suction cylinder 8, an annular non-porous plate, an annular porous plate, an air supply duct 6, a suction duct 7 and a spinning tunnel 11;

[0106] The cooling air duct 10 is open at both ends, has no holes in the wall, is vertically arranged, is cylindrical, and is divided into three sections: upper, middle, and lower.

[0107] Both ends of the four wire-walking cylinders 4 are open, and the cylinder walls have no holes. They are vertically arranged in the upper section of the cooling air cylinder 10. The upper ends of the four wire-walking cylinders 4 are flush with the upper end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular non-porous plate. The lower ends of the four wire-walking cylinders 4 are flush with the lower end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular porous plate. The cross-circular ring is composed of a circular ring and a cross in it. The cross divides the interior of the circular ring into four equal parts. The four wire-walking cylinders 4, the upper section of the cooling air cylinder 10, the cross-circular non-porous plate, and the cross-circular porous plate together form an air supply cavity; the cross sections of the four wire-walking cylinders 4 at various positions are all fan-shaped and have the same size;

[0108] like Figure 4 As shown, a plurality of grooves are provided on the inner wall of the middle section of the cooling air duct 10 for suppressing separation of the boundary layer from the cooling air duct 10. The boundary layer is a fluid layer formed due to viscosity when the cooling air 5 flows through the inner wall surface of the cooling air duct 10. The grooves are circular pit grooves 13 arranged in a staggered lattice structure. The cooling air 5 generates small circular pit groove refraction flows 14 at the circular pit grooves 13. The diameter of the circular pit grooves 13 is 4 mm, the groove depth is 2.5 mm, and the center distance between any two adjacent circular pits is 9.5 mm.

[0109] The suction cylinder 8 is open at both ends, and has no holes in the cylinder wall. It is vertically arranged in the lower section of the cooling air cylinder 10 and coaxial therewith. The upper end of the suction cylinder 8 is flush with the upper end of the lower section of the cooling air cylinder 10 and the two are connected by an annular porous plate. The lower end of the suction cylinder 8 is flush with the lower end of the lower section of the cooling air cylinder 10 and the two are connected by an annular non-porous plate. The suction cylinder 8, the annular non-porous plate, the annular porous plate, and the lower section of the cooling air cylinder 10 together form a suction chamber; the inner diameter of the cooling air cylinder 10 is 100 mm, the length of the upper section is 110 mm, the length of the middle section is 1150 mm, and the length of the lower section is 140 mm; the outer diameter of the wire drum 4 is 60 mm smaller than the inner diameter of the cooling air cylinder 10; the outer diameter of the suction cylinder 8 is 60 mm smaller than the inner diameter of the cooling air cylinder 10;

[0110] The air supply duct 6 is arranged horizontally and communicated with the air supply cavity; the suction duct 7 is arranged horizontally and communicated with the suction cavity; the inner diameter of the air supply duct 6 is 100 mm, and the inner diameter of the suction duct 7 is 100 mm;

[0111] The spinneret holes on the spinneret are rectangular with an aspect ratio of 9:1. The spinneret holes on the spinneret are distributed in four areas, and the four areas are respectively located directly above the hollow parts of the four wire barrels 4;

[0112] The spinning manifold 1 is located above the cooling air cylinder 10, with the slow cooling zone 2 and the windless zone 3 between them. The slow cooling zone 2 is located above the windless zone 3. The filament bundle 9 coming out of the spinning manifold passes through the slow cooling zone 2 and the windless zone 3 and enters the wire drum 4. Then the filament bundle 9 enters the cooling air cylinder 10. The flow direction of the cooling air 5 is parallel to the running direction of the filament bundle 9. The height of the slow cooling zone 2 is 95mm; the height of the windless zone 3 is 45mm.

[0113] The spinning shaft 11 is located below the cooling air cylinder 10 and connected thereto; the length of the spinning shaft 11 is 700 mm.

[0114] Example 2B

[0115] A method for preparing polyester industrial yarn for airbags, using the apparatus for preparing polyester industrial yarn for airbags as described in Example 2A above, wherein the spinning process comprises: extruding the polyester melt through a spinneret → cooling in a slow cooling zone → cooling in a windless zone → cooling in a cooling duct → oiling → stretching with six pairs of hot rollers → shaping → interlacing → winding;

[0116] The spinning process parameters are: ambient temperature 40℃; spinning temperature 295℃; slow cooling zone temperature 310℃; cooling air temperature 35℃; cooling air speed 0.6m / s; suction force of the suction pipe 0.2Pa; speed of the first pair of hot rollers 490m / min, temperature 60℃; speed of the second pair of hot rollers 500m / min, temperature 95℃; speed of the third pair of hot rollers 1850m / min, temperature 130℃; speed of the fourth pair of hot rollers 2995m / min, temperature 244℃; speed of the fifth pair of hot rollers 2840m / min, temperature 240℃; speed of the sixth pair of hot rollers 2650m / min, temperature 202℃; total stretching ratio 5.99, main stretching ratio 3.70, secondary stretching ratio 1.62; winding speed 2700m / min; spinning tension 80cN.

[0117] The prepared polyester industrial yarn for airbags has a linear density of 550dtex, a porosity of 144F, a breaking strength of 8cN / dtex, an elongation at break of 29%, a yarn unevenness CV value of 0.8%, a dry heat shrinkage rate of 4.12%, a hair degradation rate of 0.85%, and a fiber flatness of 3.5.

[0118] Example 3A

[0119] like Figure 1-Figure 3The device for producing polyester industrial yarn for airbags shown in the figure consists of a spinning box 1, a spinneret, a cooling air cylinder 10, four wire drums 4, a cross-circular non-porous plate, a cross-circular porous plate, a suction cylinder 8, an annular non-porous plate, an annular porous plate, an air supply duct 6, a suction duct 7 and a spinning tunnel 11;

[0120] The cooling air duct 10 is open at both ends, has no holes in the wall, is vertically arranged, is cylindrical, and is divided into three sections: upper, middle, and lower.

[0121] Both ends of the four wire-walking cylinders 4 are open, and the cylinder walls have no holes. They are vertically arranged in the upper section of the cooling air cylinder 10. The upper ends of the four wire-walking cylinders 4 are flush with the upper end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular non-porous plate. The lower ends of the four wire-walking cylinders 4 are flush with the lower end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular porous plate. The cross-circular ring is composed of a circular ring and a cross in it. The cross divides the interior of the circular ring into four equal parts. The four wire-walking cylinders 4, the upper section of the cooling air cylinder 10, the cross-circular non-porous plate, and the cross-circular porous plate together form an air supply cavity; the cross sections of the four wire-walking cylinders 4 at various positions are all fan-shaped and have the same size;

[0122] like Figure 4 As shown, a plurality of grooves are provided on the inner wall of the middle section of the cooling air duct 10 for suppressing separation of the boundary layer from the cooling air duct 10. The boundary layer is a fluid layer formed due to viscosity when the cooling air 5 flows through the inner wall surface of the cooling air duct 10. The grooves are circular pit grooves 13 arranged in a staggered lattice structure. The cooling air 5 generates small circular pit groove refraction flows 14 at the circular pit grooves 13. The diameter of the circular pit grooves 13 is 3 mm, the groove depth is 2 mm, and the center distance between any two adjacent circular pits is 10 mm.

[0123] The suction cylinder 8 is open at both ends, and has no holes in the cylinder wall. It is vertically arranged in the lower section of the cooling air cylinder 10 and coaxial therewith. The upper end of the suction cylinder 8 is flush with the upper end of the lower section of the cooling air cylinder 10 and the two are connected by an annular porous plate. The lower end of the suction cylinder 8 is flush with the lower end of the lower section of the cooling air cylinder 10 and the two are connected by an annular non-porous plate. The suction cylinder 8, the annular non-porous plate, the annular porous plate, and the lower section of the cooling air cylinder 10 together form a suction chamber; the inner diameter of the cooling air cylinder 10 is 150 mm, the length of the upper section is 150 mm, the length of the middle section is 1100 mm, and the length of the lower section is 110 mm; the outer diameter of the wire drum 4 is 40 mm smaller than the inner diameter of the cooling air cylinder 10; the outer diameter of the suction cylinder 8 is 40 mm smaller than the inner diameter of the cooling air cylinder 10;

[0124] The air supply duct 6 is arranged horizontally and communicated with the air supply cavity; the suction duct 7 is arranged horizontally and communicated with the suction cavity; the inner diameter of the air supply duct 6 is 110 mm, and the inner diameter of the suction duct 7 is 110 mm;

[0125] The spinneret holes on the spinneret are rectangular with an aspect ratio of 10:1. The spinneret holes on the spinneret are distributed in four areas, and the four areas are respectively located directly above the hollow parts of the four wire barrels 4;

[0126] The spinning manifold 1 is located above the cooling air cylinder 10, with the slow cooling zone 2 and the windless zone 3 between them. The slow cooling zone 2 is located above the windless zone 3. The filament bundle 9 coming out of the spinning manifold passes through the slow cooling zone 2 and the windless zone 3 and enters the wire drum 4. Then the filament bundle 9 enters the cooling air cylinder 10. The flow direction of the cooling air 5 is parallel to the running direction of the filament bundle 9. The height of the slow cooling zone 2 is 95 mm; the height of the windless zone 3 is 50 mm.

[0127] The spinning shaft 11 is located below the cooling air cylinder 10 and connected thereto; the length of the spinning shaft 11 is 600 mm.

[0128] Example 3B

[0129] A method for preparing polyester industrial yarn for airbags, using the apparatus for preparing polyester industrial yarn for airbags as described in Example 3A above, wherein the spinning process comprises: extruding the polyester melt through a spinneret → cooling in a slow cooling zone → cooling in a windless zone → cooling in a cooling duct → oiling → stretching with six pairs of hot rollers → shaping → interlacing → winding;

[0130] The spinning process parameters are: ambient temperature 36°C; spinning temperature 300°C; slow cooling zone temperature 295°C; cooling air temperature 30°C; cooling air speed 0.8m / s; suction force of the suction pipe 0.1Pa; speed of the first pair of hot rollers 500m / min, temperature 60°C; speed of the second pair of hot rollers 510m / min, temperature 95°C; speed of the third pair of hot rollers 2030m / min, temperature 130°C; speed of the fourth pair of hot rollers 2870m / min, temperature 245°C; speed of the fifth pair of hot rollers 2720m / min, temperature 244°C; speed of the sixth pair of hot rollers 2550m / min, temperature 190°C; total stretching ratio 5.63, primary stretching ratio 3.98, secondary stretching ratio 1.41; winding speed 2600m / min; spinning tension 70cN.

[0131] The prepared polyester industrial yarn for airbags has a linear density of 420dtex, a pore count of 96F, a breaking strength of 7.6cN / dtex, an elongation at break of 30%, a yarn unevenness CV value of 0.65%, a dry heat shrinkage rate of 4.08%, a hair degradation rate of 1%, and a fiber flatness of 4.2.

[0132] Example 4A

[0133] like Figure 1-Figure 3The device for producing polyester industrial yarn for airbags shown in the figure consists of a spinning box 1, a spinneret, a cooling air cylinder 10, four wire drums 4, a cross-circular non-porous plate, a cross-circular porous plate, a suction cylinder 8, an annular non-porous plate, an annular porous plate, an air supply duct 6, a suction duct 7 and a spinning tunnel 11;

[0134] The cooling air duct 10 is open at both ends, has no holes in the wall, is vertically arranged, is cylindrical, and is divided into three sections: upper, middle, and lower.

[0135] Both ends of the four wire-walking cylinders 4 are open, and the cylinder walls have no holes. They are vertically arranged in the upper section of the cooling air cylinder 10. The upper ends of the four wire-walking cylinders 4 are flush with the upper end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular non-porous plate. The lower ends of the four wire-walking cylinders 4 are flush with the lower end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular porous plate. The cross-circular ring is composed of a circular ring and a cross in it. The cross divides the interior of the circular ring into four equal parts. The four wire-walking cylinders 4, the upper section of the cooling air cylinder 10, the cross-circular non-porous plate, and the cross-circular porous plate together form an air supply cavity; the cross sections of the four wire-walking cylinders 4 at various positions are all fan-shaped and have the same size;

[0136] like Figure 5 and Figure 6 As shown, a plurality of grooves are provided on the inner wall of the middle section of the cooling air duct 10 for suppressing the separation of the boundary layer from the cooling air duct 10. The boundary layer is a fluid layer formed due to the viscosity when the cooling air 5 flows through the inner wall surface of the cooling air duct 10. The groove is a non-circular pit groove 15. The cooling air 5 generates a small non-circular pit groove refraction flow 16 at the non-circular pit groove 15. The non-circular pit groove 15 is a V-shaped groove. The size of the non-circular pit groove 15 gradually decreases from the groove opening to the groove bottom. The groove opening is oblong, the length of the oblong is 15 mm and the width is 3 mm. The groove bottom is a line segment shape, and the length of the groove bottom is = The length of the oblong is equal to the width of the oblong, and the groove depth is 2.2 mm. The non-circular pit grooves 15 are divided into multiple groups. The non-circular pit grooves 15 of the same group are distributed along the circumferential spacing of the middle section of the cooling air duct 10 with a spacing of 6 mm. The non-circular pit grooves 15 of different groups are distributed along the axial spacing of the middle section of the cooling air duct 10 with a spacing of 10 mm. For the same non-circular pit groove 15, the short symmetry axis of the oblong and the perpendicular bisector of the line segment are parallel to the axial direction of the cooling air duct 10, and the straight line containing the center of the oblong and the midpoint of the line segment is perpendicular to and intersects the central axis of the cooling air duct 10.

[0137] The suction cylinder 8 is open at both ends, and has no holes in the cylinder wall. It is vertically arranged in the lower section of the cooling air cylinder 10 and coaxial therewith. The upper end of the suction cylinder 8 is flush with the upper end of the lower section of the cooling air cylinder 10 and the two are connected by an annular porous plate. The lower end of the suction cylinder 8 is flush with the lower end of the lower section of the cooling air cylinder 10 and the two are connected by an annular non-porous plate. The suction cylinder 8, the annular non-porous plate, the annular porous plate, and the lower section of the cooling air cylinder 10 together form a suction chamber; the inner diameter of the cooling air cylinder 10 is 120 mm, the length of the upper section is 120 mm, the length of the middle section is 1200 mm, and the length of the lower section is 120 mm; the outer diameter of the wire drum 4 is 50 mm smaller than the inner diameter of the cooling air cylinder 10; the outer diameter of the suction cylinder 8 is 50 mm smaller than the inner diameter of the cooling air cylinder 10;

[0138] The air supply duct 6 is arranged horizontally and communicated with the air supply cavity; the suction duct 7 is arranged horizontally and communicated with the suction cavity; the inner diameter of the air supply duct 6 is 120 mm, and the inner diameter of the suction duct 7 is 120 mm;

[0139] The spinneret holes on the spinneret are rectangular with an aspect ratio of 7.1:1. The spinneret holes on the spinneret are distributed in four areas, and the four areas are respectively located directly above the hollow parts of the four wire barrels 4;

[0140] The spinning manifold 1 is located above the cooling duct 10, with the slow cooling zone 2 and the windless zone 3 between them. The slow cooling zone 2 is located above the windless zone 3. The filament bundle 9 coming out of the spinning manifold passes through the slow cooling zone 2 and the windless zone 3 and enters the wire drum 4. Then, the filament bundle 9 enters the cooling duct 10. The flow direction of the cooling air 5 is parallel to the running direction of the filament bundle 9. The height of the slow cooling zone 2 is 100 mm; the height of the windless zone 3 is 55 mm.

[0141] The spinning shaft 11 is located below the cooling air cylinder 10 and is connected thereto; the length of the spinning shaft 11 is 650 mm.

[0142] Example 4B

[0143] A method for preparing polyester industrial yarn for airbags, using the apparatus for preparing polyester industrial yarn for airbags as described in Example 4A above, wherein the spinning process comprises: extruding the polyester melt through a spinneret → cooling in a slow cooling zone → cooling in a windless zone → cooling in a cooling duct → oiling → stretching with six pairs of hot rollers → shaping → interlacing → winding;

[0144] The spinning process parameters are: ambient temperature 37°C; spinning temperature 305°C; slow cooling zone temperature 295°C; cooling air temperature 32°C; cooling air speed 0.9m / s; suction force of the suction pipe 0.08Pa; speed of the first pair of hot rollers 560m / min, temperature 65°C; speed of the second pair of hot rollers 565m / min, temperature 90°C; speed of the third pair of hot rollers 2150m / min, temperature 123°C; speed of the fourth pair of hot rollers 3600m / min, temperature 210°C; speed of the fifth pair of hot rollers 3620m / min, temperature 210°C; speed of the sixth pair of hot rollers 3420m / min, temperature 180°C; total stretching ratio 6.37, primary stretching ratio 3.81, secondary stretching ratio 1.67; winding speed 3610m / min; spinning tension 75cN.

[0145] The linear density of the polyester industrial yarn for airbags is 440dtex, the number of holes is 144F, the breaking strength is 7.9cN / dtex, the breaking elongation is 32%, the CV value of the yarn unevenness is 0.9%, the dry heat shrinkage is 4.14%, the yarn degradation rate is 0.95%, and the fiber flatness is 4.

[0146] Example 5A

[0147] like Figure 1-Figure 3 The device for producing polyester industrial yarn for airbags shown in the figure consists of a spinning box 1, a spinneret, a cooling air cylinder 10, four wire drums 4, a cross-circular non-porous plate, a cross-circular porous plate, a suction cylinder 8, an annular non-porous plate, an annular porous plate, an air supply duct 6, a suction duct 7 and a spinning tunnel 11;

[0148] The cooling air duct 10 is open at both ends, has no holes in the wall, is vertically arranged, is cylindrical, and is divided into three sections: upper, middle, and lower.

[0149] Both ends of the four wire-walking cylinders 4 are open, and the cylinder walls have no holes. They are vertically arranged in the upper section of the cooling air cylinder 10. The upper ends of the four wire-walking cylinders 4 are flush with the upper end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular non-porous plate. The lower ends of the four wire-walking cylinders 4 are flush with the lower end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular porous plate. The cross-circular ring is composed of a circular ring and a cross in it. The cross divides the interior of the circular ring into four equal parts. The four wire-walking cylinders 4, the upper section of the cooling air cylinder 10, the cross-circular non-porous plate, and the cross-circular porous plate together form an air supply cavity; the cross sections of the four wire-walking cylinders 4 at various positions are all fan-shaped and have the same size;

[0150] like Figure 5 and Figure 6As shown, a plurality of grooves are provided on the inner wall of the middle section of the cooling air duct 10 for suppressing the separation of the boundary layer from the cooling air duct 10. The boundary layer is a fluid layer formed due to the viscosity when the cooling air 5 flows through the inner wall surface of the cooling air duct 10. The groove is a non-circular pit groove 15. The cooling air 5 generates a small non-circular pit groove refraction flow 16 at the non-circular pit groove 15. The non-circular pit groove 15 is a V-shaped groove. The size of the non-circular pit groove 15 gradually decreases from the groove opening to the groove bottom. The groove opening is an oblong shape with a length of 9 mm and a width of 3.5 mm. The groove bottom is a line segment shape with a length of the groove bottom = The length of the oblong is equal to the width of the oblong, and the groove depth is 2.1 mm. The non-circular pit grooves 15 are divided into multiple groups. The non-circular pit grooves 15 of the same group are distributed along the circumferential spacing of the middle section of the cooling air duct 10 with a spacing of 5 mm. The non-circular pit grooves 15 of different groups are distributed along the axial spacing of the middle section of the cooling air duct 10 with a spacing of 9.5 mm. For the same non-circular pit groove 15, the short symmetry axis of the oblong and the perpendicular bisector of the line segment are parallel to the axial direction of the cooling air duct 10, and the straight line containing the center of the oblong and the midpoint of the line segment is perpendicular to and intersects the central axis of the cooling air duct 10.

[0151] The suction cylinder 8 is open at both ends, and has no holes in the cylinder wall. It is vertically arranged in the lower section of the cooling air cylinder 10 and coaxial therewith. The upper end of the suction cylinder 8 is flush with the upper end of the lower section of the cooling air cylinder 10 and the two are connected by an annular porous plate. The lower end of the suction cylinder 8 is flush with the lower end of the lower section of the cooling air cylinder 10 and the two are connected by an annular non-porous plate. The suction cylinder 8, the annular non-porous plate, the annular porous plate, and the lower section of the cooling air cylinder 10 together form a suction chamber; the inner diameter of the cooling air cylinder 10 is 140 mm, the length of the upper section is 150 mm, the length of the middle section is 1000 mm, and the length of the lower section is 150 mm; the outer diameter of the wire drum 4 is 50 mm smaller than the inner diameter of the cooling air cylinder 10; the outer diameter of the suction cylinder 8 is 50 mm smaller than the inner diameter of the cooling air cylinder 10;

[0152] The air supply duct 6 is arranged horizontally and communicated with the air supply cavity; the suction duct 7 is arranged horizontally and communicated with the suction cavity; the inner diameter of the air supply duct 6 is 120 mm, and the inner diameter of the suction duct 7 is 120 mm;

[0153] The spinneret holes on the spinneret are rectangular with an aspect ratio of 8:1. The spinneret holes on the spinneret are distributed in four areas, and the four areas are respectively located directly above the hollow parts of the four wire barrels 4;

[0154] The spinning manifold 1 is located above the cooling duct 10, with the slow cooling zone 2 and the windless zone 3 between them. The slow cooling zone 2 is located above the windless zone 3. The filament bundle 9 emerging from the spinning manifold passes through the slow cooling zone 2 and the windless zone 3 and enters the wire drum 4. The filament bundle 9 then enters the cooling duct 10. The flow direction of the cooling air 5 is parallel to the running direction of the filament bundle 9. The height of the slow cooling zone 2 is 105 mm; the height of the windless zone 3 is 45 mm.

[0155] The spinning shaft 11 is located below the cooling air cylinder 10 and is connected thereto; the length of the spinning shaft 11 is 650 mm.

[0156] Example 5B

[0157] A method for preparing polyester industrial yarn for airbags, using the apparatus for preparing polyester industrial yarn for airbags as described in Example 5A above, wherein the spinning process comprises: extruding the polyester melt through a spinneret → cooling in a slow cooling zone → cooling in a windless zone → cooling in a cooling duct → oiling → stretching with six pairs of hot rollers → shaping → interlacing → winding;

[0158] The spinning process parameters are: ambient temperature 39°C; spinning temperature 305°C; slow cooling zone temperature 305°C; cooling air temperature 35°C; cooling air speed 0.8m / s; suction force of the suction pipe 0.06Pa; speed of the first pair of hot rollers 430m / min, temperature 65°C; speed of the second pair of hot rollers 450m / min, temperature 100°C; speed of the third pair of hot rollers 1900m / min, temperature 125°C; speed of the fourth pair of hot rollers 2650m / min, temperature 220°C; speed of the fifth pair of hot rollers 2580m / min, temperature 225°C; speed of the sixth pair of hot rollers 2380m / min, temperature 190°C; total stretching ratio 5.89, primary stretching ratio 4.22, secondary stretching ratio 1.39; winding speed 2550m / min; spinning tension 62cN.

[0159] The prepared polyester industrial yarn for airbags has a linear density of 600 dtex, a porosity of 144F, a breaking strength of 8.1 cN / dtex, an elongation at break of 30%, a yarn unevenness CV value of 0.75%, a dry heat shrinkage rate of 4.1%, a hair degradation rate of 0.88%, and a fiber flatness of 3.8.

[0160] Example 6A

[0161] like Figure 1-Figure 3 The device for producing polyester industrial yarn for airbags shown in the figure consists of a spinning box 1, a spinneret, a cooling air cylinder 10, four wire drums 4, a cross-circular non-porous plate, a cross-circular porous plate, a suction cylinder 8, an annular non-porous plate, an annular porous plate, an air supply duct 6, a suction duct 7 and a spinning tunnel 11;

[0162] The cooling air duct 10 is open at both ends, has no holes in the wall, is vertically arranged, is cylindrical, and is divided into three sections: upper, middle, and lower.

[0163] Both ends of the four wire-walking cylinders 4 are open, and the cylinder walls have no holes. They are vertically arranged in the upper section of the cooling air cylinder 10. The upper ends of the four wire-walking cylinders 4 are flush with the upper end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular non-porous plate. The lower ends of the four wire-walking cylinders 4 are flush with the lower end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular porous plate. The cross-circular ring is composed of a circular ring and a cross in it. The cross divides the interior of the circular ring into four equal parts. The four wire-walking cylinders 4, the upper section of the cooling air cylinder 10, the cross-circular non-porous plate, and the cross-circular porous plate together form an air supply cavity; the cross sections of the four wire-walking cylinders 4 at various positions are all fan-shaped and have the same size;

[0164] like Figure 5 and Figure 6 As shown, a plurality of grooves are provided on the inner wall of the middle section of the cooling air duct 10 for suppressing the separation of the boundary layer from the cooling air duct 10. The boundary layer is a fluid layer formed due to the viscosity when the cooling air 5 flows through the inner wall surface of the cooling air duct 10. The groove is a non-circular pit groove 15. The cooling air 5 generates a small non-circular pit groove refraction flow 16 at the non-circular pit groove 15. The non-circular pit groove 15 is a V-shaped groove. The size of the non-circular pit groove 15 gradually decreases from the groove opening to the groove bottom. The groove opening is oblong, the length of the oblong is 11 mm and the width is 3.5 mm. The groove bottom is a line segment shape, and the length of the groove bottom is 1.5 mm. = length of the oblong - width of the oblong, the groove depth is 2.5mm, the non-circular pit grooves 15 are divided into multiple groups, the non-circular pit grooves 15 of the same group are distributed along the circumferential spacing of the middle section of the cooling air duct 10 with a spacing of 4mm, and the non-circular pit grooves 15 of different groups are distributed along the axial spacing of the middle section of the cooling air duct 10 with a spacing of 10mm. For the same non-circular pit groove 15, the short symmetry axis of the oblong and the perpendicular bisector of the line segment are parallel to the axial direction of the cooling air duct 10, and the straight line containing the center of the oblong and the midpoint of the line segment is perpendicular to and intersects the central axis of the cooling air duct 10;

[0165] The suction cylinder 8 is open at both ends, and has no holes in the cylinder wall. It is vertically arranged in the lower section of the cooling air cylinder 10 and coaxial therewith. The upper end of the suction cylinder 8 is flush with the upper end of the lower section of the cooling air cylinder 10 and the two are connected by an annular porous plate. The lower end of the suction cylinder 8 is flush with the lower end of the lower section of the cooling air cylinder 10 and the two are connected by an annular non-porous plate. The suction cylinder 8, the annular non-porous plate, the annular porous plate, and the lower section of the cooling air cylinder 10 together form a suction chamber; the inner diameter of the cooling air cylinder 10 is 120 mm, the length of the upper section is 110 mm, the length of the middle section is 1200 mm, and the length of the lower section is 140 mm; the outer diameter of the wire drum 4 is 40 mm smaller than the inner diameter of the cooling air cylinder 10; the outer diameter of the suction cylinder 8 is 40 mm smaller than the inner diameter of the cooling air cylinder 10;

[0166] The air supply duct 6 is arranged horizontally and communicated with the air supply cavity; the suction duct 7 is arranged horizontally and communicated with the suction cavity; the inner diameter of the air supply duct 6 is 110 mm, and the inner diameter of the suction duct 7 is 110 mm;

[0167] The spinneret holes on the spinneret are rectangular with an aspect ratio of 9:1. The spinneret holes on the spinneret are distributed in four areas, and the four areas are respectively located directly above the hollow parts of the four wire barrels 4;

[0168] The spinning manifold 1 is located above the cooling air cylinder 10, with the slow cooling zone 2 and the windless zone 3 between them. The slow cooling zone 2 is located above the windless zone 3. The filament bundle 9 coming out of the spinning manifold passes through the slow cooling zone 2 and the windless zone 3 and enters the wire drum 4. Then, the filament bundle 9 enters the cooling air cylinder 10. The flow direction of the cooling air 5 is parallel to the running direction of the filament bundle 9. The height of the slow cooling zone 2 is 105mm; the height of the windless zone 3 is 50mm.

[0169] The spinning shaft 11 is located below the cooling air cylinder 10 and connected thereto; the length of the spinning shaft 11 is 600 mm.

[0170] Example 6B

[0171] A method for preparing polyester industrial yarn for airbags, using the apparatus for preparing polyester industrial yarn for airbags described in Example 6A above, wherein the spinning process comprises: extruding the polyester melt through a spinneret → cooling in a slow cooling zone → cooling in a windless zone → cooling in a cooling duct → oiling → stretching with six pairs of hot rollers → shaping → interlacing → winding;

[0172] The spinning process parameters are: ambient temperature 40℃; spinning temperature 310℃; slow cooling zone temperature 320℃; cooling air temperature 33℃; cooling air speed 1.0m / s; suction force of the suction pipe 0.2Pa; speed of the first pair of hot rollers 460m / min, temperature 70℃; speed of the second pair of hot rollers 580m / min, temperature 90℃; speed of the third pair of hot rollers 2260m / min, temperature 135℃; speed of the fourth pair of hot rollers 3200m / min, temperature 235℃; speed of the fifth pair of hot rollers 3100m / min, temperature 240℃; speed of the sixth pair of hot rollers 2950m / min, temperature 220℃; total stretching ratio 5.52, primary stretching ratio 3.90, secondary stretching ratio 1.42; winding speed 3050m / min; spinning tension 75cN.

[0173] The prepared polyester industrial yarn for airbags has a linear density of 550dtex, a porosity of 96F, a breaking strength of 7.8cN / dtex, an elongation at break of 31%, a yarn unevenness CV value of 0.6%, a dry heat shrinkage rate of 4.04%, a hair degradation rate of 1.1%, and a fiber flatness of 3.6.

[0174] Example 7A

[0175] like Figure 1-Figure 3The device for producing polyester industrial yarn for airbags shown in the figure consists of a spinning box 1, a spinneret, a cooling air cylinder 10, four wire drums 4, a cross-circular non-porous plate, a cross-circular porous plate, a suction cylinder 8, an annular non-porous plate, an annular porous plate, an air supply duct 6, a suction duct 7 and a spinning tunnel 11;

[0176] The cooling air duct 10 is open at both ends, has no holes in the wall, is vertically arranged, is cylindrical, and is divided into three sections: upper, middle, and lower.

[0177] Both ends of the four wire-walking cylinders 4 are open, and the cylinder walls have no holes. They are vertically arranged in the upper section of the cooling air cylinder 10. The upper ends of the four wire-walking cylinders 4 are flush with the upper end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular non-porous plate. The lower ends of the four wire-walking cylinders 4 are flush with the lower end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular porous plate. The cross-circular ring is composed of a circular ring and a cross in it. The cross divides the interior of the circular ring into four equal parts. The four wire-walking cylinders 4, the upper section of the cooling air cylinder 10, the cross-circular non-porous plate, and the cross-circular porous plate together form an air supply cavity; the cross sections of the four wire-walking cylinders 4 at various positions are all fan-shaped and have the same size;

[0178] like Figure 5 and Figure 7 As shown, a plurality of grooves for suppressing the separation of the boundary layer from the cooling air duct 10 are provided on the inner wall of the middle section of the cooling air duct 10. The boundary layer is a fluid layer formed due to the viscosity when the cooling air 5 flows through the inner wall surface of the cooling air duct 10. The groove is a non-circular pit groove 15. The cooling air 5 generates a small non-circular pit groove refraction flow 16 at the non-circular pit groove 15. The non-circular pit groove 15 is an inverted equal-height trapezoidal groove. The size of the non-circular pit groove 15 gradually decreases from the groove opening to the groove bottom. The groove opening is oblong, the length of the oblong is 20 mm and the width is 4 mm. The groove bottom is rectangular and the groove depth is 2.2 m. m, the angle θ between the groove wall and the central axis of the non-circular pit groove 15 is 30°, the non-circular pit grooves 15 are divided into multiple groups, the non-circular pit grooves 15 of the same group are distributed at a circumferential spacing of 5 mm along the middle section of the cooling air cylinder 10, and the non-circular pit grooves 15 of different groups are distributed at an axial spacing of 9 mm along the middle section of the cooling air cylinder 10. For the same non-circular pit groove 15, the short symmetry axis of the oblong and the short symmetry axis of the rectangle are parallel to the axial direction of the cooling air cylinder 10, and the straight line containing the center of the oblong and the center of the rectangle is perpendicular to and intersects the central axis of the cooling air cylinder 10;

[0179] The suction cylinder 8 is open at both ends, and has no holes in the cylinder wall. It is vertically arranged in the lower section of the cooling air cylinder 10 and coaxial therewith. The upper end of the suction cylinder 8 is flush with the upper end of the lower section of the cooling air cylinder 10 and the two are connected by an annular porous plate. The lower end of the suction cylinder 8 is flush with the lower end of the lower section of the cooling air cylinder 10 and the two are connected by an annular non-porous plate. The suction cylinder 8, the annular non-porous plate, the annular porous plate, and the lower section of the cooling air cylinder 10 together form a suction chamber; the inner diameter of the cooling air cylinder 10 is 200mm, the length of the upper section is 140mm, the length of the middle section is 1150mm, and the length of the lower section is 110mm; the outer diameter of the wire drum 4 is 50mm smaller than the inner diameter of the cooling air cylinder 10; the outer diameter of the suction cylinder 8 is 50mm smaller than the inner diameter of the cooling air cylinder 10;

[0180] The air supply duct 6 is arranged horizontally and communicated with the air supply cavity; the suction duct 7 is arranged horizontally and communicated with the suction cavity; the inner diameter of the air supply duct 6 is 120 mm, and the inner diameter of the suction duct 7 is 120 mm;

[0181] The spinneret holes on the spinneret are rectangular with an aspect ratio of 10:1. The spinneret holes on the spinneret are distributed in four areas, and the four areas are respectively located directly above the hollow parts of the four wire barrels 4;

[0182] The spinning manifold 1 is located above the cooling duct 10, with the slow cooling zone 2 and the windless zone 3 between them. The slow cooling zone 2 is located above the windless zone 3. The filament bundle 9 coming out of the spinning manifold passes through the slow cooling zone 2 and the windless zone 3 and enters the wire drum 4. Then, the filament bundle 9 enters the cooling duct 10. The flow direction of the cooling air 5 is parallel to the running direction of the filament bundle 9. The height of the slow cooling zone 2 is 95 mm; the height of the windless zone 3 is 45 mm.

[0183] The spinning shaft 11 is located below the cooling air cylinder 10 and connected thereto; the length of the spinning shaft 11 is 700 mm.

[0184] Example 7B

[0185] A method for preparing polyester industrial yarn for airbags, using the apparatus for preparing polyester industrial yarn for airbags as described in Example 7A above, wherein the spinning process comprises: extruding the polyester melt through a spinneret → cooling in a slow cooling zone → cooling in a windless zone → cooling in a cooling duct → oiling → stretching with six pairs of hot rollers → shaping → interlacing → winding;

[0186] The spinning process parameters are: ambient temperature 36°C; spinning temperature 300°C; slow cooling zone temperature 310°C; cooling air temperature 34°C; cooling air speed 0.5m / s; suction force of the suction pipe 0.15Pa; speed of the first pair of hot rollers 480m / min, temperature 65°C; speed of the second pair of hot rollers 500m / min, temperature 95°C; speed of the third pair of hot rollers 2100m / min, temperature 132°C; speed of the fourth pair of hot rollers 3000m / min, temperature 245°C; speed of the fifth pair of hot rollers 2900m / min, temperature 245°C; speed of the sixth pair of hot rollers 2700m / min, temperature 205°C; total stretching ratio 6.00, primary stretching ratio 4.20, secondary stretching ratio 1.43; winding speed 2800m / min; spinning tension 65cN.

[0187] The prepared polyester industrial yarn for airbags has a linear density of 450dtex, a porosity of 144F, a breaking strength of 8cN / dtex, an elongation at break of 30%, a yarn unevenness CV value of 0.9%, a dry heat shrinkage rate of 4%, a hair degradation rate of 1.12%, and a fiber flatness of 3.9.

[0188] Example 8A

[0189] like Figure 1-Figure 3 The device for producing polyester industrial yarn for airbags shown in the figure consists of a spinning box 1, a spinneret, a cooling air cylinder 10, four wire drums 4, a cross-circular non-porous plate, a cross-circular porous plate, a suction cylinder 8, an annular non-porous plate, an annular porous plate, an air supply duct 6, a suction duct 7 and a spinning tunnel 11;

[0190] The cooling air duct 10 is open at both ends, has no holes in the wall, is vertically arranged, is cylindrical, and is divided into three sections: upper, middle, and lower.

[0191] Both ends of the four wire-walking cylinders 4 are open, and the cylinder walls have no holes. They are vertically arranged in the upper section of the cooling air cylinder 10. The upper ends of the four wire-walking cylinders 4 are flush with the upper end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular non-porous plate. The lower ends of the four wire-walking cylinders 4 are flush with the lower end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular porous plate. The cross-circular ring is composed of a circular ring and a cross in it. The cross divides the interior of the circular ring into four equal parts. The four wire-walking cylinders 4, the upper section of the cooling air cylinder 10, the cross-circular non-porous plate, and the cross-circular porous plate together form an air supply cavity; the cross sections of the four wire-walking cylinders 4 at various positions are all fan-shaped and have the same size;

[0192] like Figure 5 and Figure 7As shown, a plurality of grooves for suppressing the separation of the boundary layer from the cooling air duct 10 are provided on the inner wall of the middle section of the cooling air duct 10. The boundary layer is a fluid layer formed due to the viscosity when the cooling air 5 flows through the inner wall surface of the cooling air duct 10. The groove is a non-circular pit groove 15. The cooling air 5 generates a small non-circular pit groove refraction flow 16 at the non-circular pit groove 15. The non-circular pit groove 15 is an inverted equal-height trapezoidal groove. The size of the non-circular pit groove 15 gradually decreases from the groove opening to the groove bottom. The groove opening is oblong, the length of the oblong is 10 mm and the width is 3.6 mm. The groove bottom is rectangular and the groove depth is 2 mm. The angle θ between the groove wall and the central axis of the non-circular pit groove 15 is 20°. The non-circular pit grooves 15 are divided into multiple groups. The non-circular pit grooves 15 of the same group are distributed at a circumferential spacing of 6 mm along the middle section of the cooling air cylinder 10. The non-circular pit grooves 15 of different groups are distributed at an axial spacing of 9.5 mm along the middle section of the cooling air cylinder 10. For the same non-circular pit groove 15, the short symmetry axis of the oblong and the short symmetry axis of the rectangle are both parallel to the axial direction of the cooling air cylinder 10. The straight line on which the center of the oblong and the center of the rectangle are located is perpendicular to and intersects the central axis of the cooling air cylinder 10.

[0193] The suction cylinder 8 is open at both ends, and has no holes in the cylinder wall. It is vertically arranged in the lower section of the cooling air cylinder 10 and coaxial therewith. The upper end of the suction cylinder 8 is flush with the upper end of the lower section of the cooling air cylinder 10 and the two are connected by an annular porous plate. The lower end of the suction cylinder 8 is flush with the lower end of the lower section of the cooling air cylinder 10 and the two are connected by an annular non-porous plate. The suction cylinder 8, the annular non-porous plate, the annular porous plate, and the lower section of the cooling air cylinder 10 together form a suction chamber; the inner diameter of the cooling air cylinder 10 is 110mm, the length of the upper section is 130mm, the length of the middle section is 1100mm, and the length of the lower section is 150mm; the outer diameter of the wire drum 4 is 60mm smaller than the inner diameter of the cooling air cylinder 10; the outer diameter of the suction cylinder 8 is 60mm smaller than the inner diameter of the cooling air cylinder 10;

[0194] The air supply duct 6 is arranged horizontally and communicated with the air supply cavity; the suction duct 7 is arranged horizontally and communicated with the suction cavity; the inner diameter of the air supply duct 6 is 110 mm, and the inner diameter of the suction duct 7 is 110 mm;

[0195] The spinneret holes on the spinneret are rectangular with an aspect ratio of 7.1:1. The spinneret holes on the spinneret are distributed in four areas, and the four areas are respectively located directly above the hollow parts of the four wire barrels 4;

[0196] The spinning manifold 1 is located above the cooling duct 10, with the slow cooling zone 2 and the windless zone 3 between them. The slow cooling zone 2 is located above the windless zone 3. The filament bundle 9 coming out of the spinning manifold passes through the slow cooling zone 2 and the windless zone 3 and enters the wire drum 4. Then, the filament bundle 9 enters the cooling duct 10. The flow direction of the cooling air 5 is parallel to the running direction of the filament bundle 9. The height of the slow cooling zone 2 is 100 mm; the height of the windless zone 3 is 55 mm.

[0197] The spinning shaft 11 is located below the cooling air cylinder 10 and connected thereto; the length of the spinning shaft 11 is 700 mm.

[0198] Example 8B

[0199] A method for preparing polyester industrial yarn for airbags, using the apparatus for preparing polyester industrial yarn for airbags as described in Example 8A above, wherein the spinning process comprises: extruding the polyester melt through a spinneret → cooling in a slow cooling zone → cooling in a windless zone → cooling in a cooling duct → oiling → stretching with six pairs of hot rollers → shaping → interlacing → winding;

[0200] The spinning process parameters are: ambient temperature 38°C; spinning temperature 291°C; slow cooling zone temperature 290°C; cooling air temperature 35°C; cooling air speed 0.8m / s; suction force of the suction pipe 0.18Pa; speed of the first pair of hot rollers 540m / min, temperature 70°C; speed of the second pair of hot rollers 550m / min, temperature 100°C; speed of the third pair of hot rollers 2050m / min, temperature 128°C; speed of the fourth pair of hot rollers 3500m / min, temperature 250°C; speed of the fifth pair of hot rollers 3400m / min, temperature 250°C; speed of the sixth pair of hot rollers 3200m / min, temperature 215°C; total stretching ratio 6.36, primary stretching ratio 3.73, secondary stretching ratio 1.71; winding speed 3450m / min; spinning tension 68cN.

[0201] The prepared polyester industrial yarn for airbags has a linear density of 560 dtex, a porosity of 96F, a breaking strength of 7.9 cN / dtex, an elongation at break of 29%, a yarn unevenness CV value of 1%, a dry heat shrinkage rate of 4.1%, a hair degradation rate of 1.05%, and a fiber flatness of 3.65.

[0202] Example 9A

[0203] like Figure 1-Figure 3 The device for producing polyester industrial yarn for airbags shown in the figure consists of a spinning box 1, a spinneret, a cooling air cylinder 10, four wire drums 4, a cross-circular non-porous plate, a cross-circular porous plate, a suction cylinder 8, an annular non-porous plate, an annular porous plate, an air supply duct 6, a suction duct 7 and a spinning tunnel 11;

[0204] The cooling air duct 10 is open at both ends, has no holes in the wall, is vertically arranged, is cylindrical, and is divided into three sections: upper, middle, and lower.

[0205] Both ends of the four wire-walking cylinders 4 are open, and the cylinder walls have no holes. They are vertically arranged in the upper section of the cooling air cylinder 10. The upper ends of the four wire-walking cylinders 4 are flush with the upper end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular non-porous plate. The lower ends of the four wire-walking cylinders 4 are flush with the lower end of the upper section of the cooling air cylinder 10, and the five are connected by a cross-circular porous plate. The cross-circular ring is composed of a circular ring and a cross in it. The cross divides the interior of the circular ring into four equal parts. The four wire-walking cylinders 4, the upper section of the cooling air cylinder 10, the cross-circular non-porous plate, and the cross-circular porous plate together form an air supply cavity; the cross sections of the four wire-walking cylinders 4 at various positions are all fan-shaped and have the same size;

[0206] like Figure 5 and Figure 7 As shown, a plurality of grooves are provided on the inner wall of the middle section of the cooling air duct 10 for suppressing the separation of the boundary layer from the cooling air duct 10. The boundary layer is a fluid layer formed due to the viscosity when the cooling air 5 flows through the inner wall surface of the cooling air duct 10. The groove is a non-circular pit groove 15. The cooling air 5 generates a small non-circular pit groove refraction flow 16 at the non-circular pit groove 15. The non-circular pit groove 15 is an inverted equal-height trapezoidal groove. The size of the non-circular pit groove 15 gradually decreases from the groove opening to the groove bottom. The groove opening is oblong, the length of the oblong is 14 mm and the width is 3.8 mm. The groove bottom is rectangular and the groove depth is 2.5 mm, the angle θ between the groove wall and the central axis of the non-circular pit groove 15 is 25°, the non-circular pit grooves 15 are divided into multiple groups, the non-circular pit grooves 15 of the same group are distributed at a circumferential spacing of 4 mm along the middle section of the cooling air cylinder 10, and the non-circular pit grooves 15 of different groups are distributed at an axial spacing of 9 mm along the middle section of the cooling air cylinder 10. For the same non-circular pit groove 15, the short symmetry axis of the oblong and the short symmetry axis of the rectangle are both parallel to the axial direction of the cooling air cylinder 10, and the straight line containing the center of the oblong and the center of the rectangle is perpendicular to and intersects the central axis of the cooling air cylinder 10;

[0207] The suction cylinder 8 is open at both ends, and has no holes in the cylinder wall. It is vertically arranged in the lower section of the cooling air cylinder 10 and coaxial therewith. The upper end of the suction cylinder 8 is flush with the upper end of the lower section of the cooling air cylinder 10 and the two are connected by an annular porous plate. The lower end of the suction cylinder 8 is flush with the lower end of the lower section of the cooling air cylinder 10 and the two are connected by an annular non-porous plate. The suction cylinder 8, the annular non-porous plate, the annular porous plate, and the lower section of the cooling air cylinder 10 together form a suction chamber; the inner diameter of the cooling air cylinder 10 is 160mm, the length of the upper section is 120mm, the length of the middle section is 1000mm, and the length of the lower section is 120mm; the outer diameter of the wire drum 4 is 60mm smaller than the inner diameter of the cooling air cylinder 10; the outer diameter of the suction cylinder 8 is 60mm smaller than the inner diameter of the cooling air cylinder 10;

[0208] The air supply duct 6 is arranged horizontally and communicated with the air supply cavity; the suction duct 7 is arranged horizontally and communicated with the suction cavity; the inner diameter of the air supply duct 6 is 100 mm, and the inner diameter of the suction duct 7 is 100 mm;

[0209] The spinneret holes on the spinneret are rectangular with an aspect ratio of 8:1. The spinneret holes on the spinneret are distributed in four areas, and the four areas are respectively located directly above the hollow parts of the four wire barrels 4;

[0210] The spinning manifold 1 is located above the cooling air cylinder 10, with the slow cooling zone 2 and the windless zone 3 between them. The slow cooling zone 2 is located above the windless zone 3. The filament bundle 9 coming out of the spinning manifold passes through the slow cooling zone 2 and the windless zone 3 and enters the wire drum 4. Then, the filament bundle 9 enters the cooling air cylinder 10. The flow direction of the cooling air 5 is parallel to the running direction of the filament bundle 9. The height of the slow cooling zone 2 is 105mm; the height of the windless zone 3 is 50mm.

[0211] The spinning shaft 11 is located below the cooling air cylinder 10 and is connected thereto; the length of the spinning shaft 11 is 650 mm.

[0212] Example 9B

[0213] A method for preparing polyester industrial yarn for airbags, using the apparatus for preparing polyester industrial yarn for airbags as described in Example 9A above, wherein the spinning process comprises: extruding the polyester melt through a spinneret → cooling in a slow cooling zone → cooling in a windless zone → cooling in a cooling duct → oiling → stretching with six pairs of hot rollers → shaping → interlacing → winding;

[0214] The spinning process parameters are: ambient temperature 35℃; spinning temperature 310℃; slow cooling zone temperature 300℃; cooling air temperature 30℃; cooling air speed 0.9m / s; suction force of the suction pipe 0.15Pa; speed of the first pair of hot rollers 470m / min, temperature 60℃; speed of the second pair of hot rollers 490m / min, temperature 90℃; speed of the third pair of hot rollers 1950m / min, temperature 135℃; speed of the fourth pair of hot rollers 3100m / min, temperature 250℃; speed of the fifth pair of hot rollers 3000m / min, temperature 248℃; speed of the sixth pair of hot rollers 2800m / min, temperature 206℃; total stretching ratio 6.33, primary stretching ratio 3.98, secondary stretching ratio 1.59; winding speed 3000m / min; spinning tension 74cN.

[0215] The linear density of the polyester industrial yarn for airbags is 550dtex, the number of holes is 144F, the breaking strength is 8cN / dtex, the breaking elongation is 31%, the CV value of the yarn unevenness is 0.86%, the dry heat shrinkage rate is 4.15%, the yarn degradation rate is 1.08%, and the fiber flatness is 3.45.

Claims

1. A device for preparing polyester industrial yarn for airbags, characterized in that: It includes a spinneret, a cooling air cylinder (10), four wire feeding cylinders (4), a cross-circular non-porous plate, a cross-circular porous plate, a suction cylinder (8), an annular non-porous plate, an annular porous plate, an air supply duct (6) and a suction duct (7); The cooling air cylinder (10), the four wire-feeding cylinders (4) and the suction cylinder (8) are all open at both ends, have no holes in the cylinder wall, and are arranged vertically; The cooling air cylinder (10) is cylindrical and is divided into three sections: upper, middle and lower; Four wire-moving cylinders (4) are in the upper section, the upper ends are flush with the upper ends of the upper section and the five are connected by a cross-circular non-porous plate, the lower ends are flush with the lower ends of the upper section and the five are connected by a cross-circular porous plate, the cross-circular ring is composed of a circular ring and a cross located therein, and the four wire-moving cylinders (4), the upper section, the cross-circular non-porous plate, and the cross-circular porous plate together form an air supply chamber; The inner wall of the middle section is provided with a plurality of grooves for suppressing separation of the boundary layer from the cooling air cylinder (10), wherein the boundary layer is a fluid layer formed due to viscosity when the cooling air (5) flows through the inner wall surface of the cooling air cylinder (10); The suction cylinder (8) is in the lower section and coaxial therewith, the upper end is flush with the upper end of the lower section and the two are connected by an annular porous plate, the lower end is flush with the lower end of the lower section and the two are connected by an annular imperforate plate, and the suction cylinder (8), the annular imperforate plate, the annular porous plate, and the lower section together form a suction chamber; The air supply duct (6) is arranged horizontally and communicates with the air supply cavity; the suction duct (7) is arranged horizontally and communicates with the suction cavity; The spinneret holes on the spinneret are distributed in four areas, and the four areas are respectively located directly above the hollow parts of the four wire barrels (4).

2. The device for preparing polyester industrial yarn for airbags according to claim 1, characterized in that: The cross-shape divides the interior of the circular ring into four equal parts; the cross-sections of the four wire-running cylinders (4) at various positions are all fan-shaped and have the same size; the spinneret holes on the spinneret are rectangular with an aspect ratio of 7.1-10:

1.

3. The device for preparing polyester industrial yarn for airbags according to claim 1, characterized in that: The grooves are circular pit grooves (13) arranged in a staggered lattice structure; the diameter of the circular pit grooves (13) is 3-4 mm, the groove depth is 2-2.5 mm, and the center distance between any two adjacent circular pits is 9-10 mm.

4. The device for preparing polyester industrial yarn for airbags according to claim 1, characterized in that: The grooves are non-circular grooves (15) and are divided into multiple groups. The non-circular grooves (15) of the same group are distributed along the circumferential spacing of the middle section and the spacing is 4-6 mm. The non-circular grooves (15) of different groups are distributed along the axial spacing of the middle section and the spacing is 9-10 mm. The non-circular pit groove (15) is gradually reduced in size from the groove opening to the groove bottom, the groove opening is oblong, the length of the oblong is 9-20 mm and the width of the oblong is 3-4 mm, the groove bottom is a line segment or a rectangle, and the groove depth is 2-2.5 mm; When the groove bottom is rectangular, the angle between the groove wall and the central axis of the non-circular pit groove (15) is θ 20-30°; For the same non-circular pit groove (15), the short symmetry axis of the oblong, the perpendicular bisector of the line segment, and the short symmetry axis of the rectangle are all parallel to the axial direction of the cooling air duct (10), and the straight line where the center of the oblong and the midpoint of the line segment or the center of the rectangle are located is perpendicular to and intersects the central axis of the cooling air duct (10).

5. The device for preparing polyester industrial yarn for airbags according to claim 1, characterized in that: The inner diameter of the cooling air cylinder (10) is 100-200 mm, the length of the upper section is 110-150 mm, the length of the middle section is 1000-1200 mm, and the length of the lower section is 110-150 mm.

6. The device for preparing polyester industrial yarn for airbags according to claim 5, characterized in that: The outer diameter of the wire-moving cylinder (4) is 40-60 mm smaller than the inner diameter of the cooling air cylinder (10).

7. The device for preparing polyester industrial yarn for airbags according to claim 5, characterized in that: The outer diameter of the suction cylinder (8) is 40-60 mm smaller than the inner diameter of the cooling air cylinder (10).

8. The device for preparing polyester industrial yarn for airbags according to claim 5, characterized in that: The inner diameter of the air supply duct (6) is 100-120 mm, and the inner diameter of the suction duct (7) is 100-120 mm.

9. The device for preparing polyester industrial yarn for airbags according to claim 1, characterized in that: The spinning box (1) is also included. The spinning box (1) is located above the cooling air cylinder (10). The slow cooling zone (2) and the windless zone (3) are located between the two. The slow cooling zone (2) is located above the windless zone (3).

10. The device for preparing polyester industrial yarn for airbags according to claim 9, characterized in that: The height of the slow cooling zone (2) is 95-105 mm; the height of the windless zone (3) is 45-55 mm.

11. The device for preparing polyester industrial yarn for airbags according to claim 1, characterized in that: It also includes a spinning tunnel (11), which is located below the cooling air cylinder (10) and connected thereto.

12. The device for preparing polyester industrial yarn for airbags according to claim 11, characterized in that: The length of the spinning shaft (11) is 600-700 mm.

13. A method for preparing polyester industrial yarn for airbags, characterized in that: A device for preparing polyester industrial yarn for airbags as described in any one of claims 1 to 12 is used.

14. The method for preparing polyester industrial yarn for airbags according to claim 13, characterized in that: The spinning process is as follows: polyester melt is extruded through the spinneret → cooled in the slow cooling zone → cooled in the windless zone → cooled in the cooling duct (10) → oiled → stretched by six pairs of hot rollers → shaped → networked → wound; Spinning process parameters include: ambient temperature 35-40℃; spinning temperature 291-310℃; slow cooling zone temperature 290-320℃; cooling air temperature 30-35℃; cooling air speed 0.5-1.0m / s; suction force of the suction pipe ≤0.2Pa; speed of the first pair of hot rollers 430-560m / min, temperature 60-70℃; speed of the second pair of hot rollers 450-580m / min, temperature 90-100℃; speed of the third pair of hot rollers 1850-2260m / min, temperature 123-1 35℃; the speed of the fourth pair of hot rollers is 2650-3600m / min, the temperature is 210-250℃; the speed of the fifth pair of hot rollers is 2580-3620m / min, the temperature is 210-250℃; the speed of the sixth pair of hot rollers is 2380-3420m / min, the temperature is 180-220℃; the total stretching ratio is 5.52-6.38, the main stretching ratio is 3.70-4.22, and the secondary stretching ratio is 1.39-1.71; the winding speed is 2550-3610m / min; the spinning tension is 60-80cN.

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