A melt-spun polyamide 56 pre-oriented yarn, textured yarn and its preparation method

Abstract

This invention provides a melt-spun polyamide 56 pre-oriented yarn, a textured yarn, and a method for preparing them. By optimizing the melt spinning process, high-performance polyamide 56 pre-oriented yarn and textured yarn are prepared. The production is stable, the mechanical properties are excellent, the textured yarn has a low breakage rate, and the fluffiness, crimping effect and dyeing performance are excellent.

Description

Technical Field

[0001] This invention belongs to the field of polyamide material technology, specifically relating to a polyamide 56 pre-oriented yarn and the texturized yarn prepared therefrom, as well as a melt spinning method. Background Technology

[0002] Melt spinning is one of the main methods for forming synthetic fibers. Melt spinning is divided into direct spinning and chip spinning. Direct spinning involves directly feeding the polymer melt after polymerization into the spinning process; chip spinning requires the polymer melt to undergo pre-spinning preparation processes such as casting, pelletizing, and drying before being fed into the spinning process.

[0003] Polyamide 6 has a high monomer content (approximately 10 wt%), and the chips require extraction before melt spinning can be achieved, making industrial-scale melt spinning currently impossible. Polyamide 66, on the other hand, is prone to gelation and dyeing difficulties during spinning, posing significant challenges to melt spinning technology for civilian yarns. While melt spinning has been partially achieved in the industrial yarn sector, the melt delivery pipes and spinning boxes require periodic disassembly, calcination, and cleaning, increasing spinning costs.

[0004] Patent CN105669969 B discloses a method for polymerizing nylon 6 and its melt spinning method. This method involves first preparing a polyamide 6 prepolymer at low temperature, pre-controlling the oligomer content in the melt, and then completing the polymerization before a large amount of cyclic oligomers are generated through a kinetic enhancement method of polycondensation reaction, obtaining a nylon 6 polymer melt of a certain molecular weight. The resulting product has an extractable content ≤1.5wt% and a cyclic dimer content ≤0.2wt%. After the polycondensation reaction kinetic enhancement is completed, the product is directly melt-spun into fibers. However, there is still no technological breakthrough or industrial application case.

[0005] Patent No. CN103668510 A discloses an apparatus and method for producing fine denier or ultrafine denier nylon 66 filaments. The apparatus includes an evaporator, a preheater, a reactor, a flash evaporator, and a post-polymerization system. Nylon 66 salt water solution is subjected to a polymerization reaction to obtain nylon 66 melt. Then, the nylon 66 melt is directly spun to prepare fine denier or ultrafine denier nylon 66 POY filaments. The spinning speed is 4200-4300 m / min. The spinning speed is low, the output is low, and the fiber strength is low.

[0006] Bio-based polyamide 56 uses bio-based pentanediamine as a monomer raw material. The carbon emissions per unit weight of bio-based polyamide 56 are more than 50% lower than those of the same weight of nylon 66 and nylon 6. The application and promotion of bio-based polyamide 56 will play a positive role in reducing my country's reliance on imports of key materials and is of great significance for addressing fossil resource dependence and sustainable development with low carbon emissions. Bio-based polyamide 56 materials possess excellent mechanical properties, quick-drying and moisture-wicking properties, skin-friendliness, abrasion resistance, good softness, and low-temperature dyeability. Currently, it has broad application prospects in civilian filaments, staple fibers, industrial yarns, continuous expanded filaments, and monofilaments. However, there are currently no relevant research or reports on the industrial-scale production of polyamide 56 pre-oriented yarns and textured yarns through melt spinning. Summary of the Invention

[0007] To meet the requirements for industrial-scale production of bio-based polyamide 56 melt spinning, this invention optimizes the melt spinning process to prepare high-performance polyamide 56 pre-oriented yarn and textured yarn. The production is stable, the mechanical properties are excellent, the textured yarn has a low breakage rate, and the fluffiness, crimping effect and dyeing performance are excellent.

[0008] The first objective of this invention is to provide a melt-spun polyamide 56 pre-oriented yarn, wherein the fineness of the melt-spun polyamide 56 pre-oriented yarn is ≤300 dtex; and / or,

[0009] The unevenness of the melt-spun polyamide 56 pre-oriented yarn is ≤1.1%, preferably ≤1.0%, more preferably ≤0.9%, and even more preferably ≤0.8%, for example 0.7-0.9%; and / or,

[0010] The breaking strength of the melt-spun polyamide 56 pre-oriented yarn is 3.0-4.5 cN / dtex; the coefficient of variation (CV)% of breaking strength is ≤4%, preferably ≤3.5%, more preferably ≤3.0%, and even more preferably ≤2.5%; and / or,

[0011] The elongation at break of the melt-spun polyamide 56 pre-oriented yarn is 60-95%; the coefficient of variation (CV) of the elongation at break is ≤4.5%, preferably ≤4.0%, more preferably ≤3.5%, and even more preferably ≤3.0%; and / or,

[0012] The initial modulus of the melt-spun polyamide 56 pre-oriented yarn is 15-45 cN / dtex; and / or,

[0013] The dyeing uniformity (grey calorie) of the melt-spun polyamide 56 pre-oriented yarn is ≥3.5 grade, preferably ≥4.0 grade, more preferably ≥4.5 grade, and even more preferably ≥4.6 grade; and / or,

[0014] The dyeing double A rate of the melt-spun polyamide 56 pre-oriented yarn is ≥97%, preferably ≥98%, more preferably ≥98.5%, and even more preferably ≥99%; and / or,

[0015] The appearance double A rate of the melt-spun polyamide 56 pre-oriented yarn is ≥97%, preferably ≥98%, more preferably ≥98.5%, and even more preferably ≥99%.

[0016] In some specific embodiments, the fineness is 10–200 dtex or 10–150 dtex.

[0017] In some specific embodiments, the breaking strength of the melt-spun polyamide 56 pre-oriented yarn is, for example, 3.2-4.4 cN / dtex, or 3.4-4.3 cN / dtex, or 3.5-4.2 cN / dtex.

[0018] In some specific embodiments, the elongation at break of the melt-spun polyamide 56 pre-oriented yarn is, for example, 65-90%, 68-85%, or 72-80%.

[0019] In some specific embodiments, the initial modulus of the melt-spun polyamide 56 pre-oriented yarn is, for example, 18-42 cN / dtex, or 20-40 cN / dtex, or 22-31 cN / dtex.

[0020] The second objective of this invention is to provide a method for preparing the melt-spun polyamide 56 pre-oriented yarn, which includes at least the following steps: polyamide 56 melt is fed to a spinning box via a melt booster pump, a melt filter, and a melt conveying pipeline to form nascent yarn; the nascent yarn is cooled, oiled, and wound to obtain melt-spun polyamide 56 pre-oriented yarn.

[0021] When the polyamide 56 melt is a bright melt, its titanium dioxide content is 0; when the polyamide 56 melt is a semi-dull melt, its titanium dioxide content is 0.25-0.35 wt%, and more preferably 0.28-0.33 wt%.

[0022] In some specific embodiments, the relative viscosity of the polyamide 56 melt is 2.35-3.0, preferably 2.4-2.9, more preferably 2.45-2.85, and even more preferably 2.5-2.8.

[0023] In some specific embodiments, the polyamide 56 melt-terminated amino content is 30-100 mmol / kg, preferably 35-90 mmol / kg, more preferably 40-80 mmol / kg, and even more preferably 43-70 mmol / kg.

[0024] In some specific embodiments, the equilibrium moisture content of the polyamide 56 melt is 300-900 ppm, preferably 350-850 ppm, more preferably 400-800 ppm, and even more preferably 450-750 ppm.

[0025] In some specific embodiments, the preparation method of the polyamide 56 melt includes the following steps: mixing pentanediamine, adipic acid and water evenly to obtain a polyamide 56 salt solution, and then obtaining the polyamide 56 melt through prepolymerization, flash evaporation and polycondensation.

[0026] In some specific embodiments, the molar ratio of pentanediamine to adipic acid is (1-1.08):1.

[0027] In some specific embodiments, the concentration of the polyamide 56 salt solution is 42-78 wt%, preferably 45-75 wt%, more preferably 48-70 wt%, and even more preferably 50-65 wt%.

[0028] In some specific embodiments, the pH value of the polyamide 56 salt solution is 6.2-9.0, preferably 6.6-8.8, more preferably 7.2-8.6, and even more preferably 7.4-8.4.

[0029] In some specific embodiments, the prepolymer pressure is 1.4-2.4 MPa, more preferably 1.5-2.3 MPa, and even more preferably 1.6-2.2 MPa; the prepolymer temperature is 170-265°C, preferably 190-260°C, more preferably 210-255°C, and even more preferably 220-253°C.

[0030] In some specific embodiments, the pressure of the polycondensation is -(0-0.08) MPa, preferably -(0.01-0.07) MPa, more preferably -(0.02-0.06) MPa, and even more preferably -(0.03-0.05) MPa; the temperature of the polycondensation is 265-290℃, preferably 268-288℃, more preferably 270-285℃, and even more preferably 272-284℃.

[0031] In some specific embodiments, the titanium dioxide is added during the flash evaporation process.

[0032] In some specific embodiments, when the polyamide 56 melt is a semi-matte melt, the dispersed particle size of titanium dioxide in the polyamide 56 melt is 0.1-0.6 μm. Preferably, the proportion of titanium dioxide dispersed particle size of 0.2-0.4 μm is above 96%; more preferably, the proportion of titanium dioxide dispersed particle size of 0.2-0.3 μm is above 92%.

[0033] In some specific embodiments, the melt transport length of the polyamide 56 melt from the melt booster pump to the spinning box is 8-60m, preferably 12-55m, more preferably 14-50m, and even more preferably 16-45m.

[0034] In some specific embodiments, the melt residence time of the polyamide 56 melt from the melt booster pump to the spinning box is 10-50 min, preferably 12-44 min, more preferably 14-40 min, and even more preferably 16-35 min.

[0035] In some specific embodiments, the temperature of the melt conveying pipeline is controlled at 265-290°C, preferably 268-287°C, more preferably 272-285°C, and even more preferably 274-283°C.

[0036] In some specific embodiments, the dynamic viscosity of the polyamide 56 melt is controlled from the melt booster pump to the spinning box to be ≥180 Pa*s, more preferably ≥200 Pa*s, and even more preferably ≥220 Pa*s, for example, 180-350 Pa*s.

[0037] In some specific embodiments, the temperature of the spinning box is 272-293°C.

[0038] In some specific embodiments, the pressure of the spinning assembly in the spinning box is 12-23 MPa.

[0039] In some specific embodiments, the polyamide 56 melt is transported to the spinning box through a melt pipeline, accurately metered by a metering pump, and then injected into the spinning assembly, where it is ejected from the spinneret to form nascent filaments.

[0040] In some preferred embodiments, a saturated superheated steam device and a monomer suction device are provided below the spinning box. The inventors discovered that by injecting the saturated superheated steam from around the bottom of the spinneret, the polyamide oligomers overflowing from the spinneret orifices and fiber surfaces dissolve in the saturated superheated steam and are then carried away by the monomer suction device. This keeps the spinneret and the area below it clean, extends the spinneret cleaning cycle, reduces the occurrence of yarn breakage and single filament breakage caused by oligomers during spinning, and effectively improves the stability and yield of spinning production.

[0041] In some specific embodiments, the temperature of the saturated superheated steam device is controlled at 95-260°C, further at 110-250°C, and even further at 120-240°C.

[0042] In some specific embodiments, the pressure of the saturated superheated steam device is controlled at 0.8-2.2 bar, further at 1.0-2.0 bar, and even further at 1.2-1.8 bar.

[0043] In some specific embodiments, the pressure of the monomer suction device is controlled to be ≥0.6MPa, further ≥0.65MPa, and even further ≥0.7MPa.

[0044] In some specific embodiments, the oiling agent used for oiling can be a commercially available polyamide pre-oriented yarn oiling agent, such as DAKO oiling agent, Takemoto oiling agent, Kokai oiling agent, Sima oiling agent, etc.

[0045] In some specific embodiments, the winding speed is ≥4300m / min, preferably ≥4400m / min, more preferably ≥4450m / min, and even more preferably ≥4500m / min; for example, 4300-5500m / min.

[0046] In some specific embodiments, the winding is performed between two guide discs. The nascent yarn passes sequentially through guide disc CR1 and guide disc CR2 before being wound into shape. The underfeed of guide disc CR1 and guide disc CR2 is ≤50m / min, for example, 10-50m / min, preferably ≤40m / min, and more preferably ≤30m / min. The overfeed between guide disc CR2 and the winding head is ≤50m / min, for example, 10-50m / min, preferably ≤40m / min, and more preferably ≤30m / min.

[0047] In some specific embodiments, the speed of the CR1 guide wire disc is 4300-5200 m / min, preferably 4400-5100 m / min, more preferably 4450-5000 m / min, and even more preferably 4500-4800 m / min.

[0048] In some specific embodiments, the speed of the CR2 guide wire disc is 4330-5250 m / min, preferably 4430-5150 m / min, more preferably 4480-5050 m / min, and even more preferably 4530-4850 m / min.

[0049] In some specific embodiments, the number of broken monofilaments of the polyamide 56 pre-oriented yarn is ≤2 per spinning position 24h, preferably ≤1 per spinning position 24h, and more preferably ≤0 per spinning position 24h.

[0050] In some specific embodiments, the yield of the melt-spun polyamide 56 pre-oriented yarn is ≥96%, preferably ≥97%, more preferably ≥98%, and even more preferably ≥98.5%.

[0051] A third objective of this invention is to provide a polyamide 56 textured yarn prepared from the above-mentioned melt-spun polyamide 56 pre-oriented yarn, wherein the polyamide 56 textured yarn has a breaking strength of 3.2-5.2 cN / dtex; and / or,

[0052] The elongation at break of the polyamide 56 elastic filament is 22-35%; and / or,

[0053] The boiling water shrinkage rate of the polyamide 56 elastic yarn is ≤8%, preferably ≤7.5%, more preferably ≤7%, and even more preferably ≤6%; for example, 5-7%; and / or,

[0054] The crimp shrinkage rate of the polyamide 56 elastic yarn is ≥30%, preferably ≥33%, more preferably ≥37%, and even more preferably ≥40%; for example, 40-50%; and / or,

[0055] The polyamide 56 elastic yarn has a crimp stability of ≥30%, preferably ≥35%, more preferably ≥38%, and even more preferably ≥40%; for example, 40-50%; and / or,

[0056] The breakage rate of the polyamide 56 elastic yarn is ≤5%, preferably ≤4%, more preferably ≤3%, and even more preferably ≤2%; and / or,

[0057] The polyamide 56 elastic yarn has a dyeing double A rate of ≥95%, preferably ≥96%, more preferably ≥97%, and even more preferably ≥98%.

[0058] In some specific embodiments, the tensile strength of the polyamide 56 elastic filament is, for example, 3.3-5.0 cN / dtex, or 3.4-4.8 cN / dtex, or 3.5-4.5 cN / dtex.

[0059] In some specific embodiments, the elongation at break of the polyamide 56 elastic filament is, for example, 23-34%, or 24-33%, or 25-32%.

[0060] In some specific embodiments, the method for preparing the polyamide 56 textured yarn includes at least the following steps: the melt-spun polyamide 56 pre-oriented yarn is sequentially passed through a yarn guide and a yarn cutter to the first roller; then sequentially subjected to hot stretching, cooling and shaping, and false twisting, and passed through the second roller; then treated by a network nozzle, passed through the third roller, oiled, and wound to obtain the polyamide 56 textured yarn;

[0061] Wherein, the temperature of the hot stretching is 140-200℃, and the multiple is 1.25-1.40; and / or, the friction plate of the false twist is a C-type disc, a D-type disc, or a PU-type disc; and / or, the D / Y ratio of the false twist is 1.6-2.2; and / or, the T2 processing tension of the false twist is controlled to be 0.8-1.1 times the T1 processing tension; and the winding speed is 600-800m / min.

[0062] In some specific embodiments, the temperature of the hot stretching is 180°C, and the multiple is 1.30; the friction plate of the false twist is a C-shaped disc; the D / Y ratio of the false twist is 1.7; the T2 processing tension of the false twist is controlled to be 1.1 times the T1 processing tension; and the winding speed is 600 m / min.

[0063] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention. All reagents and raw materials used in the present invention are commercially available.

[0064] The positive and progressive effects of this invention are as follows:

[0065] First, the 1,5-pentanediamine, the raw material for producing polyamide 56 pre-oriented yarn and textured yarn provided by this invention, is produced by a biological method. It is a green material that does not rely on petroleum resources and does not cause serious pollution to the environment. Furthermore, it can reduce carbon dioxide emissions, reduce the greenhouse effect, and adapt to the carbon neutrality and development trend.

[0066] Secondly, by using the melt direct spinning method for preparing polyamide 56 pre-oriented yarn described in this invention, by optimizing the melt direct spinning process and controlling parameters such as melt conveying length, residence time, conveying pipeline temperature, and dynamic viscosity, not only is stable production of melt direct spinning polyamide 56 pre-oriented yarn achieved, but the gel content in the melt booster pump to the spinning box can also be effectively reduced.

[0067] Specifically, the annual production capacity of the melt-spun polyamide 56 pre-oriented yarn can reach 10,000 to 50,000 tons / line, preferably 20,000 tons / line; the spinning positions can be 192, 144, 120, or 96 positions / line or less; the number of spinning heads can be 8-24 heads / position, preferably 10-18 heads / position. The preparation method provided by this invention saves the steps of melt pelletizing, chip drying, and screw melting in the chip spinning process, thus significantly reducing the production cost of polyamide 56 pre-oriented yarn. The gel content can be controlled below 1.2 wt% / 6 months, preferably ≤1.0 wt% / 6 months, more preferably ≤0.8 wt% / 6 months, and even more preferably ≤0.6 wt% / 6 months. The reduction in gel content greatly reduces the number of times the melt pipe and spinning box need to be disassembled, calcined, and cleaned, thereby reducing production costs.

[0068] Third, the melt-spun polyamide 56 pre-oriented yarn and the texturized yarn prepared by the present invention have stable production, excellent mechanical properties, low yarn breakage rate, and excellent bulkiness, crimping effect and dyeing performance. Detailed Implementation

[0069] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Experimental methods in the following embodiments that do not specify specific conditions are performed according to conventional methods and conditions, or according to the product instructions.

[0070] Test method:

[0071] (1) Relative viscosity: The Ubbelohde viscometer was used for the concentrated sulfuric acid method: A 0.25±0.0002g sample of dried polyamide melt was accurately weighed and dissolved in 50mL of concentrated sulfuric acid (96wt%). The flow time t0 of the concentrated sulfuric acid and the flow time t0 of the polyamide sample solution were measured and recorded in a 25℃ constant temperature water bath. Viscosity calculation formula: Relative viscosity = t / t0; t—solution flow time; t0—solvent flow time.

[0072] (2) Terminal amino group: determined by automatic titrator.

[0073] (3) Moisture content: determined by Karl Fischer moisture titrator.

[0074] (4) Fineness: determined according to GB / T 14343.

[0075] (5) Yarn unevenness: Yarn unevenness refers to the degree of variation in thickness of the yarn along its own length, including uneven yarn diameter and uneven linear density. The testing equipment is the Uster yarn evenness tester.

[0076] (6) Breaking strength, coefficient of variation of breaking strength (CV)%, elongation at break, coefficient of variation of elongation at break (CV)%: according to GB / T 14344-2008 Test method for tensile properties of chemical fibers; apply a pretension of 0.05±0.005cN / dtex, a holding distance of 250mm, and a tensile speed of 1000mm / min.

[0077] (7) Initial modulus: determined according to GB / T 14344-2008.

[0078] (8) Boiling water shrinkage rate: determined according to GB / 6505-2008.

[0079] (9) Dyeing uniformity (grey card) / grade: according to FZ / T 50008 Test method for dyeing uniformity of nylon filament.

[0080] (10) Dyeing double A rate: Dyeing double A rate = ((weight of fibers with dyeing uniformity ≥ 4.5 grade) / total weight of all dyed fibers) × 100%.

[0081] (11) Appearance double A rate of silk cake: manual judgment.

[0082] (12) Number of times a single filament breaks: manually counted.

[0083] (13) Production rate: Production rate = (mass of finished fiber prepared / total mass of polyamide melt added) × 100%.

[0084] (14) Gel content: Six melt samples were randomly selected from the melt conveying pipeline after six months of production line operation. The average value was measured and the mass of the melt sample after weighing, cooling and drying was A1. After reflux extraction using Soxhlet extraction, the sample was taken out, dried, and the mass of the sample in the filter paper package was weighed as A2. The formula for calculating gel content is: gel content wt% = A2 / A1*100%.

[0085] (15) Curling shrinkage rate and curling stability: as specified in GB / T 6506.

[0086] Example 1: Bright 40dtex / 36f melt-spun polyamide 56 pre-oriented yarn

[0087] (1) Prepare a polyamide 56 salt solution by pentanediamine, adipic acid and water, and then obtain polyamide 56 melt by prepolymerization, flash evaporation and polycondensation;

[0088] The molar ratio of pentanediamine to adipic acid is 1.05:1; the concentration of the polyamide 56 salt solution is 52 wt%; and the pH value of the polyamide 56 salt solution is 7.8.

[0089] The prepolymer is subjected to a pressure of 1.6 MPa and a temperature of 248°C.

[0090] The polycondensation was carried out at a pressure of -0.03 MPa and a temperature of 278°C.

[0091] The polyamide 56 melt is a bright melt with a titanium dioxide content of 0.

[0092] The polyamide 56 melt has a relative viscosity of 2.5, a terminal amino content of 45 mmol / kg, and an equilibrium moisture content of 400 ppm.

[0093] (2) Step (1) The polyamide 56 melt is obtained and sent to the spinning box through the melt booster pump, melt filter and melt conveying pipeline to form the nascent filament. The nascent filament is cooled, oiled and wound to obtain melt direct spinning polyamide 56 pre-oriented filament.

[0094] The melt transport length of the polyamide 56 melt from the melt booster pump to the spinning box is 30m, and the melt residence time is 23min; the temperature of the melt transport pipeline is controlled at 275℃; and the dynamic viscosity of the polyamide 56 melt from the melt booster pump to the spinning box is controlled at 220pa*s.

[0095] The temperature of the spinning box is 275°C; the pressure of the spinning assembly in the spinning box is 13 MPa.

[0096] A saturated superheated steam device and a monomer suction device are installed below the spinning box. The temperature of the saturated superheated steam device is controlled at 120°C, the pressure of the saturated superheated steam device is controlled at 1.2 bar, and the pressure of the monomer suction device is controlled at 0.65 MPa.

[0097] The winding speed is 4500 m / min; the winding is carried out between two guide discs, the nascent yarn passes through guide disc CR1 and guide disc CR2 in sequence, and is then wound into shape. The underfeed of guide disc CR1 and guide disc CR2 is 30 m / min, and the overfeed of guide disc CR2 and the winding head is 40 m / min; the speed of guide disc CR1 is 4510 m / min; the speed of guide disc CR2 is 4540 m / min.

[0098] The annual production capacity of melt-spun polyamide 56 pre-oriented yarn described in this embodiment can reach 12,000 tons / line, with 96 spinning positions / line and 12 spinning heads / position.

[0099] Example 2: Bright 55dtex / 51f melt-spun polyamide 56 pre-oriented yarn

[0100] (1) Prepare a polyamide 56 salt solution by pentanediamine, adipic acid and water, and then obtain polyamide 56 melt by prepolymerization, flash evaporation and polycondensation;

[0101] The molar ratio of pentanediamine to adipic acid is 1.08:1; the concentration of the polyamide 56 salt solution is 53 wt%; and the pH value of the polyamide 56 salt solution is 8.0.

[0102] The prepolymer is subjected to a pressure of 1.7 MPa and a temperature of 250°C.

[0103] The polycondensation is carried out at a pressure of -0.05 MPa and a temperature of 282°C.

[0104] The polyamide 56 melt is a bright melt with a titanium dioxide content of 0.

[0105] The polyamide 56 melt has a relative viscosity of 2.7, a terminal amino content of 48 mmol / kg, and an equilibrium moisture content of 450 ppm.

[0106] (2) Step (1) The polyamide 56 melt is obtained and sent to the spinning box through the melt booster pump, melt filter and melt conveying pipeline to form the nascent filament. The nascent filament is cooled, oiled and wound to obtain melt direct spinning polyamide 56 pre-oriented filament.

[0107] The melt transport length of the polyamide 56 melt from the melt booster pump to the spinning box is 32m, and the melt residence time is 25min; the temperature of the melt transport pipeline is controlled at 280℃; and the dynamic viscosity of the polyamide 56 melt from the melt booster pump to the spinning box is controlled at 235pa*s.

[0108] The temperature of the spinning box is 280℃; the pressure of the spinning assembly in the spinning box is 14MPa.

[0109] A saturated superheated steam device and a monomer suction device are installed below the spinning box. The temperature of the saturated superheated steam device is controlled at 160°C, the pressure of the saturated superheated steam device is controlled at 1.3 bar, and the pressure of the monomer suction device is controlled at 0.6 MPa.

[0110] The winding speed is 4600 m / min; the winding is carried out between two guide discs, the nascent yarn passes through guide disc CR1 and guide disc CR2 in sequence, and is then wound into shape. The underfeed of guide disc CR1 and guide disc CR2 is 20 m / min, and the overfeed of guide disc CR2 and the winding head is 30 m / min; the speed of guide disc CR1 is 4610 m / min; the speed of guide disc CR2 is 4630 m / min.

[0111] The annual production capacity of melt-spun polyamide 56 pre-oriented yarn described in this embodiment can reach 30,000 tons / line, with 192 spinning positions / line and 12 spinning heads / position.

[0112] Example 3: Bright 95dtex / 48f melt-spun polyamide 56 pre-oriented yarn

[0113] (1) Prepare a polyamide 56 salt solution by pentanediamine, adipic acid and water, and then obtain polyamide 56 melt by prepolymerization, flash evaporation and polycondensation;

[0114] The molar ratio of pentanediamine to adipic acid is 1.06:1; the concentration of the polyamide 56 salt solution is 52 wt%; and the pH value of the polyamide 56 salt solution is 8.2.

[0115] The prepolymer is subjected to a pressure of 1.75 MPa and a temperature of 253 °C.

[0116] The polycondensation was carried out at a pressure of -0.06 MPa and a temperature of 284°C.

[0117] The polyamide 56 melt is a bright melt with a titanium dioxide content of 0.

[0118] The polyamide 56 melt has a relative viscosity of 2.8, a terminal amino content of 50 mmol / kg, and an equilibrium moisture content of 500 ppm.

[0119] (2) Step (1) The polyamide 56 melt is obtained and sent to the spinning box through the melt booster pump, melt filter and melt conveying pipeline to form the nascent filament. The nascent filament is cooled, oiled and wound to obtain melt direct spinning polyamide 56 pre-oriented filament.

[0120] The melt transport length of the polyamide 56 melt from the melt booster pump to the spinning box is 28m, and the melt residence time is 24min; the temperature of the melt transport pipeline is controlled at 280℃; and the dynamic viscosity of the polyamide 56 melt from the melt booster pump to the spinning box is controlled at 250pa*s.

[0121] The temperature of the spinning box is 280°C; the pressure of the spinning assembly in the spinning box is 16 MPa.

[0122] A saturated superheated steam device and a monomer suction device are installed below the spinning box. The temperature of the saturated superheated steam device is controlled at 180°C, the pressure of the saturated superheated steam device is controlled at 1.5 bar, and the pressure of the monomer suction device is controlled at 0.7 MPa.

[0123] The winding speed is 4700 m / min; the winding is carried out between two guide discs, the nascent yarn passes through guide disc CR1 and guide disc CR2 in sequence, and is then wound into shape. The underfeed of guide disc CR1 and guide disc CR2 is 20 m / min, and the overfeed of guide disc CR2 and the winding head is 20 m / min; the speed of guide disc CR1 is 4700 m / min; the speed of guide disc CR2 is 4720 m / min.

[0124] The annual production capacity of melt-spun polyamide 56 pre-oriented yarn described in this embodiment can reach 20,000 tons / line, with 96 spinning positions / line and 12 spinning heads / position.

[0125] Example 4: Semi-dull 40dtex / 36f melt-spun polyamide 56 pre-oriented yarn

[0126] (1) Prepare a polyamide 56 salt solution by pentanediamine, adipic acid and water, and then obtain polyamide 56 melt by prepolymerization, flash evaporation and polycondensation;

[0127] The molar ratio of pentanediamine to adipic acid is 1.07:1; the concentration of the polyamide 56 salt solution is 53 wt%; and the pH value of the polyamide 56 salt solution is 7.6.

[0128] The prepolymer is subjected to a pressure of 1.63 MPa and a temperature of 245°C.

[0129] The polycondensation was carried out at a pressure of -0.05 MPa and a temperature of 276°C.

[0130] The polyamide 56 melt is a bright melt, a semi-dull melt, and its titanium dioxide content is 0.31 wt%. The titanium dioxide is added during flash evaporation, and its dispersed particle size in the polyamide 56 melt is 0.1-0.6 μm, with the proportion of titanium dioxide particles with a dispersed particle size of 0.2-0.4 μm being 98.2% and the proportion of titanium dioxide particles with a dispersed particle size of 0.2-0.3 μm being 95.5%.

[0131] The polyamide 56 melt has a relative viscosity of 2.45, a terminal amino content of 43 mmol / kg, and an equilibrium moisture content of 500 ppm.

[0132] (2) Step (1) The polyamide 56 melt is obtained and sent to the spinning box through the melt booster pump, melt filter and melt conveying pipeline to form the nascent filament. The nascent filament is cooled, oiled and wound to obtain melt direct spinning polyamide 56 pre-oriented filament.

[0133] The melt transport length of the polyamide 56 melt from the melt booster pump to the spinning box is 28m, and the melt residence time is 22min; the temperature of the melt transport pipeline is controlled at 275℃; the dynamic viscosity of the polyamide 56 melt from the melt booster pump to the spinning box is controlled at 225pa*s.

[0134] The temperature of the spinning box is 277°C; the pressure of the spinning assembly in the spinning box is 15 MPa.

[0135] A saturated superheated steam device and a monomer suction device are installed below the spinning box. The temperature of the saturated superheated steam device is controlled at 170°C, the pressure of the saturated superheated steam device is controlled at 1.5 bar, and the pressure of the monomer suction device is controlled at 0.6 MPa.

[0136] The winding speed is 4500 m / min; the winding is carried out between two guide discs, the nascent yarn passes through guide disc CR1 and guide disc CR2 in sequence, and is then wound into shape. The underfeed of guide disc CR1 and guide disc CR2 is 20 m / min, and the overfeed of guide disc CR2 and the winding head is 30 m / min; the speed of guide disc CR1 is 4510 m / min; the speed of guide disc CR2 is 4530 m / min.

[0137] The annual production capacity of melt-spun polyamide 56 pre-oriented yarn described in this embodiment can reach 25,000 tons / line, with 192 spinning positions / line and 12 spinning heads / position.

[0138] Example 5: Semi-dull 55dtex / 48f melt-spun polyamide 56 pre-oriented yarn

[0139] (1) Prepare a polyamide 56 salt solution by pentanediamine, adipic acid and water, and then obtain polyamide 56 melt by prepolymerization, flash evaporation and polycondensation;

[0140] The molar ratio of pentanediamine to adipic acid is 1.05:1; the concentration of the polyamide 56 salt solution is 56 wt%; and the pH value of the polyamide 56 salt solution is 7.9.

[0141] The prepolymer is subjected to a pressure of 1.68 MPa and a temperature of 251°C.

[0142] The polycondensation is carried out at a pressure of -0.06 MPa and a temperature of 280°C.

[0143] The polyamide 56 melt is a bright melt, a semi-dull melt, and its titanium dioxide content is 0.32 wt%. The titanium dioxide is added during the flash evaporation process, and its dispersed particle size in the polyamide 56 melt is 0.1-0.6 μm, with the proportion of titanium dioxide particles with a dispersed particle size of 0.2-0.4 μm being 98.5% and the proportion of titanium dioxide particles with a dispersed particle size of 0.2-0.3 μm being 96.5%.

[0144] The polyamide 56 melt has a relative viscosity of 2.6, a terminal amino content of 52 mmol / kg, and an equilibrium moisture content of 550 ppm.

[0145] (2) Step (1) The polyamide 56 melt is obtained and sent to the spinning box through the melt booster pump, melt filter and melt conveying pipeline to form the nascent filament. The nascent filament is cooled, oiled and wound to obtain melt direct spinning polyamide 56 pre-oriented filament.

[0146] The melt transport length of the polyamide 56 melt from the melt booster pump to the spinning box is 31m, and the melt residence time is 24min; the temperature of the melt transport pipeline is controlled at 275℃; and the dynamic viscosity of the polyamide 56 melt from the melt booster pump to the spinning box is controlled at 240pa*s.

[0147] The temperature of the spinning box is 282°C; the pressure of the spinning assembly in the spinning box is 16 MPa.

[0148] A saturated superheated steam device and a monomer suction device are installed below the spinning box. The temperature of the saturated superheated steam device is controlled at 120°C, the pressure of the saturated superheated steam device is controlled at 1.5 bar, and the pressure of the monomer suction device is controlled at 0.7 MPa.

[0149] The winding speed is 4600 m / min; the winding is carried out between two guide discs, the nascent yarn passes through guide disc CR1 and guide disc CR2 in sequence, and is then wound into shape. The underfeed of guide disc CR1 and guide disc CR2 is 20 m / min, and the overfeed of guide disc CR2 and the winding head is 20 m / min; the speed of guide disc CR1 is 4600 m / min; the speed of guide disc CR2 is 4620 m / min.

[0150] The annual production capacity of melt-spun polyamide 56 pre-oriented yarn described in this embodiment can reach 30,000 tons / line, with 192 spinning positions / line and 12 spinning heads / position.

[0151] Example 6: Semi-dull 95dtex / 68f melt-spun polyamide 56 pre-oriented yarn

[0152] (1) Prepare a polyamide 56 salt solution by pentanediamine, adipic acid and water, and then obtain polyamide 56 melt by prepolymerization, flash evaporation and polycondensation;

[0153] The molar ratio of pentanediamine to adipic acid is 1.09:1; the concentration of the polyamide 56 salt solution is 57 wt%; and the pH value of the polyamide 56 salt solution is 8.2.

[0154] The prepolymer is subjected to a pressure of 1.73 MPa and a temperature of 255°C.

[0155] The polycondensation is carried out at a pressure of -0.07 MPa and a temperature of 285°C.

[0156] The polyamide 56 melt is a bright melt and a semi-dull melt, with a titanium dioxide content of 0.33 wt%. The titanium dioxide is added during flash evaporation, and its dispersed particle size in the polyamide 56 melt is 0.1-0.6 μm. The proportion of titanium dioxide particles with a dispersed particle size of 0.2-0.4 μm is 98.8%, and the proportion of titanium dioxide particles with a dispersed particle size of 0.2-0.3 μm is 97.6%.

[0157] The polyamide 56 melt has a relative viscosity of 2.76, a terminal amino content of 48 mmol / kg, and an equilibrium moisture content of 480 ppm.

[0158] (2) Step (1) The polyamide 56 melt is obtained and sent to the spinning box through the melt booster pump, melt filter and melt conveying pipeline to form the nascent filament. The nascent filament is cooled, oiled and wound to obtain melt direct spinning polyamide 56 pre-oriented filament.

[0159] The melt transport length of the polyamide 56 melt from the melt booster pump to the spinning box is 30m, and the melt residence time is 25min; the temperature of the melt transport pipeline is controlled at 275℃; and the dynamic viscosity of the polyamide 56 melt from the melt booster pump to the spinning box is controlled at 250pa*s.

[0160] The temperature of the spinning box is 282°C; the pressure of the spinning assembly in the spinning box is 17 MPa.

[0161] A saturated superheated steam device and a monomer suction device are installed below the spinning box. The temperature of the saturated superheated steam device is controlled at 130°C, the pressure of the saturated superheated steam device is controlled at 1.4 bar, and the pressure of the monomer suction device is controlled at 0.8 MPa.

[0162] The winding speed is 4700 m / min; the winding is carried out between two guide discs, the nascent yarn passes through guide disc CR1 and guide disc CR2 in sequence, and is then wound into shape. The underfeed of guide disc CR1 and guide disc CR2 is 30 m / min, and the overfeed of guide disc CR2 and the winding head is 30 m / min; the speed of guide disc CR1 is 4700 m / min; the speed of guide disc CR2 is 4730 m / min.

[0163] The annual production capacity of melt-spun polyamide 56 pre-oriented yarn described in this embodiment can reach 40,000 tons / line, with 192 spinning positions / line and 12 spinning heads / position.

[0164] Comparative Example 1: Bright 55dtex / 51f polyamide 56 pre-oriented yarn

[0165] The preparation method is the same as in Example 2, except that: the polyamide 56 melt obtained in step (1) is first granulated and dried to obtain chips, and then melted by a single screw and transported to the spinning box through the melt conveying pipeline. The chips are then spun to prepare polyamide 56 pre-oriented yarn.

[0166] Comparative Example 2: Semi-dull 55dtex / 48f polyamide 56 pre-oriented yarn

[0167] The preparation method is the same as in Example 5, except that: the polyamide 56 melt obtained in step (1) is first granulated and dried to obtain chips, and then melted by a single screw and transported to the spinning box through the melt conveying pipeline. The chips are then spun to prepare polyamide 56 pre-oriented yarn.

[0168] Comparative Example 3: Bright 55dtex / 51f polyamide 56 pre-oriented yarn

[0169] The preparation method is the same as in Example 2, except that the melt transport length of the polyamide 56 melt from the melt booster pump to the spinning box is 65m.

[0170] Comparative Example 4: Bright 55dtex / 51f polyamide 56 pre-oriented yarn

[0171] The preparation method is the same as in Example 2, except that the melt residence time of the polyamide 56 melt from the melt booster pump to the spinning box is 60 min.

[0172] Comparative Example 5: Bright 55dtex / 51f polyamide 56 pre-oriented yarn

[0173] The preparation method is the same as in Example 2, except that the temperature of the melt delivery pipeline is controlled at 295°C.

[0174] Comparative Example 6: Bright 55dtex / 51f polyamide 56 pre-oriented yarn

[0175] The preparation method is the same as in Example 2, except that the dynamic viscosity of the polyamide 56 melt is controlled to be 150 Pa*s from the melt booster pump to the spinning box.

[0176] Comparative Example 7: Bright 55dtex / 48f polyamide 56 pre-oriented yarn

[0177] The preparation method is the same as in Example 2, except that the winding is carried out between two guide discs. The nascent yarn passes through the CR1 guide disc and the CR2 guide disc in sequence and is then wound into shape. The underfeed of the CR1 guide disc and the CR2 guide disc is 65 m / min, and the overfeed of the CR2 guide disc and the winding head is 80 m / min. The speed of the CR1 guide disc is 4000 m / min, and the speed of the CR2 guide disc is 4000 m / min.

[0178] Table 1. Parameters of polyamide 56 pre-oriented yarns prepared in the examples and comparative examples.

[0179]

[0180] Polyamide 56 pre-oriented yarn obtained in the above examples and comparative examples was used as raw material to prepare polyamide 56 elastic yarn. The preparation method includes the following steps: the polyamide 56 pre-oriented yarn is passed sequentially through a yarn guide and a yarn cutter to the first roller; then it is sequentially subjected to hot stretching, cooling and shaping, false twisting, and passed through the second roller; then it is treated by a network nozzle, passed through the third roller, oiled, and wound to obtain polyamide 56 elastic yarn;

[0181] The hot stretching temperature is 180℃, and the multiple is 1.30; the friction plate for the false twist is a C-shaped disc; the D / Y ratio of the false twist is 1.7; the T2 processing tension of the false twist is controlled to be 1.1 times the T1 processing tension; and the winding speed is 600m / min.

[0182] The above Examples 1-6 and Comparative Examples 1-7 were processed into texturized wires and marked as Examples 7-12 and Comparative Examples 8-14, respectively. The performance of the texturized wires was tested and is shown in Table 2.

[0183] Table 2. Parameters of polyamide 56 elastic yarns prepared in the examples and comparative examples.

[0184]

[0185] The above description of the embodiments is provided to enable those skilled in the art to understand and use the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A melt-spun polyamide 56 pre-oriented yarn characterized in that, The breaking strength of the melt direct spinning polyamide 56 pre-oriented yarn is 3.0-4.5 cN / dtex, the breaking strength variation coefficient of the melt direct spinning polyamide 56 pre-oriented yarn is ≤3.0%; the elongation at break of the melt direct spinning polyamide 56 pre-oriented yarn is 60-95%, and the elongation at break variation coefficient is ≤3.0%; the bar unevenness of the melt direct spinning polyamide 56 pre-oriented yarn is ≤0.9%; The preparation method of the melt direct spinning polyamide 56 pre-oriented yarn at least comprises the following steps: polyamide 56 melt is sent to a spinning box through a melt booster pump, a melt filter and a melt conveying pipeline to form a nascent yarn, and the nascent yarn is cooled, oiled and wound to obtain the melt direct spinning polyamide 56 pre-oriented yarn; The melt conveying length of the polyamide 56 melt from the melt booster pump to the spinning box is 8-60 m, the melt residence time of the polyamide 56 melt from the melt booster pump to the spinning box is 10-50 min, the temperature of the melt conveying pipeline is controlled to be 265-290 ℃, and the dynamic viscosity of the polyamide 56 melt from the melt booster pump to the spinning box is controlled to be 180-350 pa*s; The winding is carried out between two godets, the nascent yarn passes through CR1 godet and CR2 godet in sequence and is then wound to form a shape, the underfeed of the CR1 godet and the CR2 godet is ≤50 m / min, the overfeed between the CR2 godet and the winding head is ≤50 m / min, the speed of the CR1 godet is 4300-5200 m / min, and the speed of the CR2 godet is 4330-5250 m / min.

2. The melt-spun polyamide 56 prec drawn yarn according to claim 1, characterized in that, The fineness of the melt direct spinning polyamide 56 pre-oriented yarn is ≤300 dtex; and / or, The initial modulus of the melt direct spinning polyamide 56 pre-oriented yarn is 15-45 cN / dtex.

3. The melt-spun polyamide 56 prec drawn yarn according to claim 1, characterized in that, The breaking strength variation coefficient of the melt direct spinning polyamide 56 pre-oriented yarn is ≤2.5%; and / or, The dyeing uniformity of the melt direct spinning polyamide 56 pre-oriented yarn is ≥3.5 grade; and / or, The dyeing double A rate of the melt direct spinning polyamide 56 pre-oriented yarn is ≥97%; and / or, The cake appearance double A rate of the melt direct spinning polyamide 56 pre-oriented yarn is ≥97%.

4. The melt-spun polyamide 56 prec drawn yarn according to claim 1, wherein, The dyeing uniformity of the melt direct spinning polyamide 56 pre-oriented yarn is ≥4.0 grade; and / or, The dyeing double A rate of the melt direct spinning polyamide 56 pre-oriented yarn is ≥98%; and / or, The cake appearance double A rate of the melt direct spinning polyamide 56 pre-oriented yarn is ≥98%.

5. The melt-spun polyamide 56 prec drawn yarn according to claim 1, wherein, The bar unevenness of the melt direct spinning polyamide 56 pre-oriented yarn is ≤0.8%; and / or, The dyeing uniformity of the melt direct spinning polyamide 56 pre-oriented yarn is ≥4.5 grade; and / or, The dyeing double A rate of the melt direct spinning polyamide 56 pre-oriented yarn is ≥98.5%; and / or, The cake appearance double A rate of the melt direct spinning polyamide 56 pre-oriented yarn is ≥98.5%.

6. The melt-spun polyamide 56 prec drawn yarn according to claim 1, wherein, The dyeing uniformity of the melt direct spinning polyamide 56 pre-oriented yarn is ≥4.6 grade; and / or, The dyeing double A rate of the melt direct spinning polyamide 56 pre-oriented yarn is ≥99%; and / or, The cake appearance double-A rate of the melt direct spinning polyamide 56 pre-oriented yarn is ≥99%.

7. The melt-spun polyamide 56 prec drawn yarn according to claim 1, characterized in that, When the polyamide 56 melt is a bright melt, the titanium dioxide content thereof is 0; when the polyamide 56 melt is a semi-dull melt, the titanium dioxide content thereof is 0.25-0.35 wt%.

8. The melt-spun polyamide 56 prec drawn yarn according to claim 1, wherein, When the polyamide 56 melt is a semi-dull melt, the titanium dioxide content thereof is 0.28-0.33 wt%; and / or, The relative viscosity of the polyamide 56 melt is 2.35-3.0; and / or, The end amino group content of the polyamide 56 melt is 30-100 mmol / kg; and / or, The equilibrium moisture content of the polyamide 56 melt is 300-900 ppm.

9. The melt-spun polyamide 56 prec drawn yarn according to claim 1, wherein, The relative viscosity of the polyamide 56 melt is 2.4-2.9; and / or, The end amino group content of the polyamide 56 melt is 35-90 mmol / kg; and / or, The equilibrium moisture content of the polyamide 56 melt is 350-850 ppm.

10. The melt-spun polyamide 56 prec drawn yarn according to claim 1, wherein, The melt conveying length of the polyamide 56 melt from the melt booster pump to the spinning beam is 12-55 m; and / or, The relative viscosity of the polyamide 56 melt is 2.45-2.85; and / or, The end amino group content of the polyamide 56 melt is 40-80 mmol / kg; and / or, The equilibrium moisture content of the polyamide 56 melt is 400-800 ppm.

11. The melt-spun polyamide 56 prec drawn yarn according to claim 1, characterized in that, The melt conveying length of the polyamide 56 melt from the melt booster pump to the spinning beam is 14-50 m; and / or, The melt residence time of the polyamide 56 melt from the melt booster pump to the spinning beam is 12-44 min; and / or, The temperature of the melt conveying pipeline is controlled to be 268-287 ℃; and / or, The relative viscosity of the polyamide 56 melt is 2.5-2.8; and / or, The end amino group content of the polyamide 56 melt is 43-70 mmol / kg; and / or, The equilibrium moisture content of the polyamide 56 melt is 450-750 ppm.

12. The melt-spun polyamide 56 prec drawn yarn according to claim 1, characterized in that, The melt conveying length of the polyamide 56 melt from the melt booster pump to the spinning beam is 16-45 m; and / or, The melt residence time of the polyamide 56 melt from the melt booster pump to the spinning beam is 14-40 min; and / or, The temperature of the melt conveying pipeline is controlled to be 272-285 ℃; and / or, The dynamic viscosity of the polyamide 56 melt is controlled to be 200-350 pa*s from the melt booster pump to the spinning beam.

13. The melt-spun polyamide 56 prec drawn yarn according to claim 1, wherein, The melt residence time of the polyamide 56 melt from the melt booster pump to the spinning beam is 16-35 min; and / or, The temperature of the melt conveying pipeline is controlled to be 274-283 ℃; and / or, The dynamic viscosity of the polyamide 56 melt is controlled to be 220-350 pa*s from the melt booster pump to the spinning beam; and / or, A saturated superheated steam device and a monomer suction device are arranged below the spinning beam.

14. The melt-spun polyamide 56 prec drawn yarn according to claim 13, characterized in that, The temperature of the saturated superheated steam device is controlled to be 95-260 ℃; and / or, The pressure of the saturated superheated steam device is controlled to be 0.8-2.2 bar; and / or, The pressure of the monomer suction device is controlled to be ≥0.6 MPa.

15. The melt-spun polyamide 56 prec drawn yarn according to claim 13, characterized in that, controlling the temperature of the saturated superheated steam device to be 110-250℃; and / or, controlling the pressure of the saturated superheated steam device to be 1.0-2.0 bar; and / or, controlling the pressure of the monomer suction device to be ≥0.65 MPa.

16. The melt-spun polyamide 56 prec drawn yarn according to claim 13, wherein, controlling the temperature of the saturated superheated steam device to be 120-240℃; and / or, controlling the pressure of the saturated superheated steam device to be 1.2-1.8 bar; and / or, controlling the pressure of the monomer suction device to be ≥0.7 MPa.

17. The melt-spun polyamide 56 prec drawn yarn according to claim 1, wherein, The winding speed is ≥4300 m / min.

18. Spandex yarn made from the melt-spun polyamide 56 pre-oriented yarn of any of claims 1 to 17, characterized in that The breaking strength of the polyamide 56 textured yarn is 3.2-5.2 cN / dtex; and / or, The breaking elongation of the polyamide 56 textured yarn is 22-35%; and / or, The boiling water shrinkage of the polyamide 56 textured yarn is ≤8%; and / or, The crimping shrinkage of the polyamide 56 textured yarn is ≥30%; and / or, The crimping stability of the polyamide 56 textured yarn is ≥30%; and / or, The yarn breakage rate of the polyamide 56 textured yarn is ≤5%; and / or, The dyeing double A rate of the polyamide 56 textured yarn is ≥95%.

19. The polyamide 56 textured yarn of claim 18, wherein, The boiling water shrinkage of the polyamide 56 textured yarn is ≤7.5%; and / or, The crimping shrinkage of the polyamide 56 textured yarn is ≥33%; and / or, The crimping stability of the polyamide 56 textured yarn is ≥35%; and / or, The yarn breakage rate of the polyamide 56 textured yarn is ≤4%; and / or, The dyeing double A rate of the polyamide 56 textured yarn is ≥96%.

20. The polyamide 56 textured yarn of claim 18, wherein, The boiling water shrinkage of the polyamide 56 textured yarn is ≤7%; and / or, The crimping shrinkage of the polyamide 56 textured yarn is ≥37%; and / or, The crimping stability of the polyamide 56 textured yarn is ≥38%; and / or, The yarn breakage rate of the polyamide 56 textured yarn is ≤3%; and / or, The dyeing double A rate of the polyamide 56 textured yarn is ≥97%.

21. The polyamide 56 textured yarn of claim 18, wherein, The boiling water shrinkage of the polyamide 56 textured yarn is ≤6%; and / or, The crimping shrinkage of the polyamide 56 textured yarn is ≥40%; and / or, The crimping stability of the polyamide 56 textured yarn is ≥40%; and / or, The yarn breakage rate of the polyamide 56 textured yarn is ≤2%; and / or, The dyeing double A rate of the polyamide 56 textured yarn is ≥98%.

22. The polyamide 56 textured yarn of claim 18, wherein, The boiling water shrinkage of the polyamide 56 textured yarn is ≤6%; and / or, The crimping shrinkage of the polyamide 56 textured yarn is ≥40%; and / or, The crimping stability of the polyamide 56 textured yarn is ≥40%; and / or, The yarn breakage rate of the polyamide 56 textured yarn is ≤2%; and / or, The dyeing double A rate of the polyamide 56 textured yarn is ≥98%. The preparation method of the polyamide 56 textured yarn at least comprises the following steps: The melt direct spinning polyamide 56 pre-oriented yarn is sequentially guided through a guide, a cutter to a first roller, then sequentially subjected to heat stretching, cooling and setting, false twisting, passes through a second roller, is subjected to network nozzle treatment, passes through a third roller, is oiled, and is wound to obtain the polyamide 56 textured yarn; wherein the temperature of the heat stretching is 140-200℃, and the multiple is 1.25-1.40; and / or the friction sheet of the false twisting is a C-shaped disc, a D-shaped disc or a PU-shaped disc; and / or the D / Y of the false twisting is 1.6-2.2; and / or the T2 processing tension of the false twisting is controlled to be 0.8-1.1 times of the T1 processing tension; and the winding speed is 600-800 m / min.

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