Polyamide 5x industrial yarn, production method thereof, and use thereof

Abstract

To provide a polyamide 56 industrial yarn having both excellent heat resistance and mechanical properties and a manufacturing method thereof.SOLUTION: In a polyamide 56 industrial yarn, a raw material for manufacturing the polyamide 56 industrial yarn includes at least a high-viscosity polyamide 56 resin; the high-viscosity polyamide 56 resin has a relative viscosity in a 96%-sulfuric acid of 2.7-4.5, an oligomer content of 0.2-1.0 wt.%, a number-average molecular weight of 18,000-40,000, a molecular-weight distribution of 0.8-1.8, a water content of 200-800 ppm, and an amino content of 20-50 mmol / kg; the polyamide 56 industrial yarn includes a thermal stabilizer; the thermal stabilizer includes one of copper acetate, potassium iodide, copper chloride, cuprous iodide, copper oxide, cuprous oxide, and combinations of these; and the thermal stabilizer is added at an amount of 10-2800 ppm based on a total weight of manufacturing materials.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to the technical field of polyamide materials, and provides a polyamide 5X industrial yarn, its production method and its use. [Background technology]

[0002] Industrial yarns can be produced by two processes, one is the direct melt spinning process and the other is the indirect chip spinning process with solid-phase tackification. Today, polyamide 66 and some polyethylene terephthalate are sometimes produced by the direct melt spinning method. However, polyamide 6 cannot currently be produced by the direct melt spinning process because it contains 8-10% by weight of monomers that need to be removed through a monomer removal process.

[0003] Dacron and Chinlon industrial yarns have the properties of high strength, low elongation, dimensional stability, fatigue resistance, aging resistance, etc. Therefore, they are widely used in the fields of tire cords, canvas, conveyor belts, airbags, parachutes, ropes, safety belts, industrial filter cloths, tents, etc. Various application fields impose relatively high requirements on the heat resistance of industrial yarn materials. At present, this is mainly achieved by the method of adding and compounding heat stabilizer master batches. However, heat stabilizer master batches are expensive. In addition, spinning manufacturers need to equip online master batch equipment during spinning, which increases the equipment investment. It is also necessary to address the compatibility of heat stabilizer master batches with the substrate. If the master batch is not added uniformly, the filaments will break during spinning, which will reduce the production yield of industrial yarns and even affect the mechanical properties of the fibers.

[0004] CN 110055602A discloses high-strength polyamide 56 industrial yarn and its manufacturing method. Traditional polyamide 56 chips are used for spinning, and the polyamide 56 chips are not heat-resistant modified, so the manufactured industrial yarn has poor heat resistance and cannot be used in fields requiring high heat resistance, such as sewing thread, tire cord, airbag thread, peeling cloth, krama, etc. A high-speed winding process with a winding speed of over 4000 m / min is adopted. Due to the high winding speed, the residence time of the fiber on different hot rollers is relatively short, that is, the high-temperature setting time of the fiber is short. In addition, the low draw ratio process is adopted, which produces fibers with low crystallinity, low orientation, low strength, and poor dimensional stability. Summary of the Invention [Problem to be solved by the invention]

[0005] The first object of the present invention is to provide a polyamide 5X industrial yarn having both excellent heat resistance and mechanical properties. The polyamide 5X industrial yarn has a heat resistant breaking strength retention of 90% or more after 4 hours of treatment at 180°C, a heat resistant breaking strength retention of 90% or more after 30 minutes of treatment at 230°C, and / or a dry heat shrinkage of 8.0% or less. The polyamide 5X includes any one of polyamide 56, polyamide 510, polyamide 512, polyamide 513, and polyamide 514. Preferably, it is polyamide 56 or polyamide 510.

[0006] According to the present invention, the quality of polyamide 5X, especially polyamide 56 resin, is optimized by adjusting its viscosity, oligomer content, molecular weight and molecular weight distribution, and water content. Secondly, the spinning process of polyamide 5X industrial yarn is optimized to improve its crystallinity and orientation, increase the set temperature and winding overfeed ratio, and reduce the subsequent stress relaxation. In this way, the present invention provides polyamide 56 industrial yarn with excellent mechanical properties and dimensional stability, having a breaking strength of 6.5 cN / dtex or more; filament breaks not more than twice per 24 hours; a production yield of 90% or more; a boiling water shrinkage rate of 8.0% or less; a fineness of 100-3500 dtex; an elongation at break of 26% or less; a crystallinity of 70% or more; and / or an orientation of 80% or more.

[0007] During the spinning process of polyamide fiber, the moisture content of the resin needs to be controlled, and is generally required to be within the range of the equilibrium moisture content. If the moisture content of the resin during spinning is too low, a melt tackifying reaction will occur during melting, the amino content will decrease, and the fluidity of the melt will deteriorate, which is unfavorable for subsequent drawing, causing filament breakage and fiber strength reduction. If the moisture content is too high, a melt degradation reaction will occur during melting, the amino content will increase, and it will be easy to cause filament breakage, ultimately leading to a decrease in production yield. When the moisture content of the polyamide 56 resin is controlled within the range of 300-800 ppm during spinning, the deoiled yarn of polyamide 56 industrial yarn has a relative viscosity of 2.7-4.5, and the absolute value of the difference between the relative viscosity of the deoiled yarn and the relative viscosity of its raw material resin is 0.12 or less; the deoiled yarn has an amino content of 20-50 mmol / kg, and the absolute value of the difference between the amino content of the deoiled yarn and the amino content of its raw material resin is 5 or less. By narrowing the fluctuation range in terms of the viscosity and amino content of the deoiled yarn, the melt uniformity of polyamide 56 can be improved, filament breakage can be reduced, and spinnability can be improved, so that the production yield of the prepared polyamide 56 industrial yarn can be increased to 90% or more.

[0008] A second object of the present invention is to provide a process for the preparation of polyamide 5X industrial yarns, in particular polyamide 56 industrial yarns.

[0009] A third object of the present invention is to provide the use of polyamide 5X industrial yarns, in particular polyamide 56 industrial yarns, in the fields of sewing threads, tire cords, airbag yarns, release fabrics, chromers, canvas, safety belts, ropes, fishing nets, industrial filter fabrics, conveyor belts, parachutes, tents, bags and suitcases. [Means for solving the problem]

[0010] In order to achieve the above objectives, the present invention provides the following solutions:

[0011] [Polyamide 5X industrial yarn] Taking polyamide 56 industrial yarn as an example, the content of copper ions in the polyamide 56 industrial yarn of the present invention is 10 to 1000 ppm, preferably 30 to 500 ppm, more preferably 50 to 200 ppm, the polyamide 56 industrial yarn has a heat resistant breaking strength retention of 90% or more, preferably 94% or more, more preferably 98% or more after treatment at 180°C for 4 hours, and / or the heat resistant breaking strength retention of 90% or more, preferably 93% or more, more preferably 96% or more after treatment at 230°C for 30 minutes, and / or the polyamide 56 industrial yarn has a dry heat shrinkage of 8.0% or less, preferably 6.0% or less, more preferably 4.0% or less.

[0012] The polyamide 56 industrial yarn comprises a heat stabilizer; preferably, the heat stabilizer comprises any one of copper acetate, potassium iodide, copper chloride, cuprous iodide, copper oxide, cuprous oxide, or combinations thereof; preferably, the heat stabilizer is added in an amount of 10 to 2800 ppm, and preferably 10 to 2500 ppm, based on the total weight of the manufacturing raw materials.

[0013] Preferably, the heat stabilizer is a composition of copper acetate and potassium iodide, the molar ratio of copper acetate to potassium iodide being 1:1-15, preferably 1:2-10, and more preferably 1:6-8, and preferably copper acetate is added in an amount of 100-500 ppm, and potassium iodide is added in an amount of 500-2500 ppm.

[0014] The polyamide 56 industrial yarn has a breaking strength of 6.5 cN / dtex or more, preferably 7.0 cN / dtex or more, more preferably 8.0 cN / dtex or more.

[0015] The deoiled polyamide 56 industrial yarn has a relative viscosity of 2.7 to 4.5, and the absolute value of the difference between the relative viscosity of the deoiled yarn and the relative viscosity of its raw material resin is 0.12 or less, preferably 0.10 or less, and more preferably 0.08 or less.

[0016] The deoiled yarn of polyamide 56 industrial yarn has an amino content of 20 to 50 mmol / kg, and the absolute value of the difference between the amino content of the deoiled yarn and the amino content of its raw material resin is 5 or less, preferably 3 or less, and more preferably 2 or less.

[0017] The filaments of the polyamide 56 industrial yarn break no more than twice per 24 hours, preferably no more than once per 24 hours, more preferably zero times per 24 hours, and the production yield of the polyamide 56 industrial yarn is 90% or more, preferably 93% or more, and even more preferably 96% or more.

[0018] The polyamide 56 industrial yarn has a boiling water shrinkage of 8.0% or less, preferably 7.0% or less, more preferably 6.0% or less, and / or the polyamide 56 industrial yarn has a fineness of 100 to 3,500 dtex, preferably 200 to 2,500 dtex, more preferably 300 to 1,800 dtex, the polyamide 56 industrial yarn has a breaking elongation of 26% or less, preferably 22% or less, and / or the polyamide 56 industrial yarn has a crystallinity of 70% or more, preferably 72% or more, more preferably 74% or more, and / or the polyamide 56 industrial yarn has an orientation degree of 80% or more, preferably 82% or more, more preferably 84% or more.

[0019] The raw materials for the production of polyamide 56 industrial yarns include at least 1,5-pentanediamine and adipic acid; or polyamide 56 obtained by polymerizing 1,5-pentanediamine and adipic acid as monomers.

[0020] 1,5-pentanediamine is prepared from bio-based raw materials by fermentation process or enzymatic conversion process.Preferably, 1,5-pentanediamine is prepared from bio-based raw materials by fermentation process or enzymatic conversion process.For example, the method for producing 1,5-pentanediamine disclosed in CN109536542A is adopted.

[0021] [Manufacturing method of polyamide 5X industrial yarn] Taking polyamide 56 industrial yarn as an example, the method includes the following steps: Here, polyamide 56 industrial yarn can be prepared by two processes, namely direct melt spinning process or chip spinning process; (1) Polymerizing 1,5-pentanediamine and adipic acid to obtain a high viscosity polyamide 56 melt, which is conveyed to a spinning beam by a melt booster pump and spun directly or by using a polyamide 56 tip, i.e., first preparing a low viscosity polyamide 56 resin, then obtaining a high viscosity polyamide 56 resin by solid-state tackification, and heating the high viscosity polyamide 56 resin to a molten state to form a polyamide 5X melt for spinning; Here, in the solid-phase tackification, the low-viscosity polyamide 56 resin is thickened by drying at a high temperature, preferably at a temperature of 120 to 180°C, preferably at a temperature of 150 to 160°C, and the drying time is 10 to 50 hours, preferably 15 to 30 hours; in the solid-phase tackification, moisture is removed by drying at a high temperature, and a high-viscosity resin is obtained by continuing the polycondensation reaction; (2) drawing the polyamide 56 melt to form a spun yarn; and (3) The raw spinning yarn is processed to obtain polyamide 56 industrial yarn.

[0022] Here, the heat stabilizer is added during the polymerization of 1,5-pentanediamine and adipic acid in step (1), or is injected online in the form of a heat stabilizer masterbatch before cutting the polymer melt into pellets, or is blended in the form of a heat stabilizer masterbatch during spinning.

[0023] When the polyamide 5X industrial yarn is a polyamide 510 industrial yarn, 1,5-pentanediamine and sebacic acid can be polymerized.

[0024] In some embodiments of the present invention, the content of copper ions in the heat stabilizer masterbatch is 0.5-10 wt %, preferably 0.8-5 wt %, and more preferably 1.2-3 wt %.

[0025] In some embodiments of the present invention, the heat stabilizer masterbatch is added in an amount of 0.3-5.0 wt%, preferably 0.5-3.0 wt%, and more preferably 0.8-2.0 wt%.

[0026] In some embodiments of the present invention, the substrate for the heat stabilizer masterbatch is either polyamide 6, polyamide 56, polyamide 66, polyamide 510, polyamide 610, polybutylene terephthalate, or a combination thereof; preferably, polyamide 6, polyamide 56 and / or polyamide 510; and more preferably, polyamide 6 and / or polyamide 56.

[0027] In some embodiments of the present invention, a method for producing a heat stabilizer masterbatch comprises the following steps: (1) Dry the substrate under vacuum or inert gas and grind it into a powder; (2) The powder obtained in step (1) is mixed with a heat stabilizer and other additives, and the mixture is pelletized. Specifically, twin-screw melt extrusion can be used for pelletization. Preferably, the processing temperature in each zone of the twin-screw extruder is 180-285°C, the screw rotation speed is 25-350r / min, the vacuum degree is -0.1MPa or less, and the filter screen is in the range of 80-200 mesh. Preferably, the substrate is polyamide 56, the processing temperature in each zone of the twin-screw extruder is 260-275°C, the screw rotation speed is 50-350r / min, the vacuum degree is -0.1MPa or less, and the filter screen is in the range of 100-150 mesh. The heat stabilizer is added in an amount of 0.5-20% by weight based on the substrate.

[0028] In some embodiments of the present invention, the heat stabilizer is a composition of copper acetate and potassium iodide, and the molar ratio of copper acetate to potassium iodide is 1:1-15, preferably 1:2-10, and more preferably 1:5-8. In some embodiments of the present invention, the heat stabilizer is cuprous iodide. Other additives include at least an antioxidant and / or a lubricant.

[0029] According to the present invention, polyamide 56 industrial yarn achieves better heat resistance and mechanical properties by adding the above heat stabilizer during polymerization. The inventors presume that the reason is as follows: First, since polyamide 56 melt has good fluidity, the heat stabilizer can be distributed uniformly in the polyamide 56 resin, and the compatibility with polyamide 56 resin is good. Second, polyamide 56 has an odd-even carbon sequence structure with a high proportion of amide bonds, and some amide bonds on different molecular chains are not bonded. After adding the heat stabilizer containing copper ions, the copper ions can play a good complexing function between amide bonds, so that the bonds between polyamide 56 molecular chains are closer, and the intermolecular force is relatively large, and therefore the mechanical properties of the prepared industrial yarn are increased.

[0030] In some embodiments of the present invention, other additives may also be added during spinning of polyamide 56 industrial yarn, the other additives including any one of a matting agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent, an optical brightener, and an antistatic agent, or a combination thereof; preferably, the other additives are added in an amount of 0-5 wt % based on the total weight of the production raw materials.

[0031] Antioxidants include, but are not limited to, any one, two, or combination of commercially available Antioxidant 1010, Antioxidant 1098, Antioxidant 168, and sodium hypophosphite. Lubricants include, but are not limited to, commercially available P861 / 3.5, PTS HOB 7119, and commercially available ET132, ET141, and Wax OP.

[0032] In step (1), the polymerization of polyamide 56 specifically includes the following steps: (1-1) 1,5-pentanediamine, adipic acid and water are mixed uniformly under inert gas or vacuum conditions to obtain a polyamide 56 salt solution; where the molar ratio of 1,5-pentanediamine to adipic acid is (0.95-1.2):1; the inert gas includes any one of nitrogen, argon or helium, or a combination thereof; In some embodiments of the present invention, the concentration of the polyamide 56 salt solution is 40% to 85%;

[0033] (1-2) Heat the polyamide 56 salt solution, increase the pressure in the reaction system to 0.3 to 2.5 MPa, degas the solution, maintain the pressure, reduce the pressure in the reaction system to 0 to 0.2 MPa, and evacuate the system to a vacuum of -(0.01 to 0.1) MPa (gauge pressure) to obtain a polyamide 56 melt; Here, the temperature of the reaction system at the pressure maintenance end is preferably 230 to 275°C; and / or the temperature of the reaction system at the pressure reduction end is preferably 240 to 285°C; and / or the temperature of the exhaust end is preferably 265 to 295°C.

[0034] In some embodiments of the present invention, in step (1), the low-viscosity polyamide 56 resin in 96% sulfuric acid has a relative viscosity of 2.0 to 2.7, preferably 2.2 to 2.6, and more preferably 2.4 to 2.5.

[0035] In some embodiments of the present invention, in step (1), the high-viscosity polyamide 56 resin in 96% sulfuric acid has a relative viscosity of 2.7 to 4.5, preferably 3.2 to 4.0, and more preferably 3.4 to 3.6; and / or the high-viscosity polyamide 56 resin has an oligomer content of 0.2 to 1.0 wt.%, and preferably 0.4 to 0.6 wt.%; and / or the high-viscosity polyamide 56 resin has a number average molecular weight distribution of 18,000 to 40,000, and preferably 25,000 to 30,000, and / or a number average molecular weight distribution of 0.8 to 1.8, and preferably has a molecular weight distribution of 1.2 to 1.5; and / or in some embodiments of the present invention, the high-viscosity polyamide 56 resin has a water content of 200 to 800 ppm, preferably 300 to 750 ppm, more preferably 350 to 700 ppm, and even more preferably 400 to 600 ppm; and / or the high-viscosity polyamide 56 resin has an amino content of 20 to 50 mmol / kg, preferably 24 to 45 mmol / kg, more preferably 28 to 40 mmol / kg, and even more preferably 32 to 36 mmol / kg.

[0036] In some embodiments of the invention, the heating in step (1) is carried out in a screw extruder, the screw extruder comprising five heating zones, the first zone having a temperature of 250-290°C, the second zone having a temperature of 260-300°C, the third zone having a temperature of 270-320°C, the fourth zone having a temperature of 280-330°C, and the fifth zone having a temperature of 280-320°C.

[0037] In some embodiments of the present invention, the spinning process in step (2) comprises the steps of: ejecting polyamide 56 resin through a spinneret plate of a spin beam to form a spun yarn.

[0038] The temperature of the spinning beam is preferably 270-330°C, more preferably 280-310°C, even more preferably 290-300°C, even more preferably 293-297°C; and / or the pressure of the spin pack of the spinning beam is 8-25 MPa, preferably 12-20 MPa, even more preferably 15-18 MPa; and / or the spinneret draw ratio of the spinneret plate is 50-400, preferably 70-300, even more preferably 80-200, even more preferably 90-100.

[0039] In some embodiments of the present invention, in step (3), the processing process includes the following steps: insulating, cooling, spin finishing, drawing, and winding the spun raw yarn emerging from the spinneret orifice to obtain polyamide 56 industrial yarn; The insulation is preferably performed in an annealing device, and the annealing temperature is 150-280°C, more preferably 200-240°C; the annealing length is 10-80mm, more preferably 20-50mm; the cooling is performed with quenching air, and the air velocity of the quenching air is 0.3-2.0m / s, more preferably 0.6-1.5m / s; the air temperature of the quenching air is 15-25°C, more preferably 17-23°C, even more preferably 19-22°C, and / or the humidity of the quenching air is 60-80%, even more preferably and / or the winding tension when winding the raw spun yarn into a shape is 50 to 300 cN, preferably 80 to 200 cN, more preferably 100 to 160 cN, and even more preferably 120 to 140 cN; or the winding speed is 2,000 to 3,800 m / min, preferably 2,500 to 3,500 m / min, and even more preferably 2,800 to 3,000 m / min; and / or the winding overfeed ratio is 5% or less, preferably 4% or less, and even more preferably 3% or less.

[0040] In some embodiments of the present invention, the drawing is carried out in four or more stages, and preferably, the drawing process includes the steps of firstly supplying the spin-finished raw yarn to a first pair of hot rollers via a godet roller and carrying out a first stage of drawing between the first pair of hot rollers and a second pair of hot rollers; carrying out a second stage of drawing between the second pair of hot rollers and a third pair of hot rollers; carrying out a third stage of drawing and a first heat setting between the third pair of hot rollers and a fourth pair of hot rollers; and then carrying out a fourth stage of drawing and a second heat setting between the fourth pair of hot rollers and a fifth pair of hot rollers; Preferably, the total draw ratio is 4.0 to 6.0; The temperature of the first heat set is 180-250°C, preferably 200-240°C; and / or the temperature of the second heat set is 200-240°C, preferably 220-230°C. Effect of the Invention

[0041] The advantageous effects of the technical solution according to the present invention include: Firstly, the raw materials for producing the polyamide 5X industrial yarn of the present invention are green materials prepared by biological processes. They do not depend on petroleum resources and do not cause serious pollution to the environment. Therefore, they can reduce carbon dioxide emissions and greenhouse effect.

[0042] Secondly, the polyamide 5X industrial yarn of the present invention has good heat resistance, mechanical properties and dimensional stability.

[0043] Thirdly, in the method for producing polyamide 5X industrial yarn according to the present invention, the heat stabilizer can be added during polymerization, so the polymerization is in-situ polymerization. If mixed thoroughly, the heat stabilizer can be evenly distributed in the polyamide 5X resin and will not affect spinning. Moreover, filament breakage is extremely rare, and production yield is increased.

[0044] Fourth, the polyamide 5X industrial yarn of the present invention can be produced by directly using the conventional equipment for producing polyamide 6 and polyamide 66 without modifying the conventional spinning equipment. Instead, by optimizing the quality of polyamide 5X resin and the spinning process, the production yield can be increased and the production cost can be reduced, which means great benefits for the spinning manufacturers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention are clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some, but not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments in the present invention and without creative work shall fall within the protection scope of the present invention.

[0046] The physical properties of the products obtained in the following Examples and Comparative Examples were measured according to the following methods. (1) Fineness: measured according to GB / T14343. (2) Breaking strength: measured in accordance with GB / T14344-2008. (3) Elongation at break: Measured in accordance with GB / T14344-2008.

[0047] (4) Heat resistance breaking strength retention: Heat resistance breaking strength retention = ((breaking strength before heat treatment - breaking strength after heat treatment) / breaking strength before heat treatment) * 100%. The breaking strength is measured according to GB / T14344-2008. An oven is used as the heat treatment device. The oven temperature is 180 ° C, the treatment time is 4 hours (hours), the oven temperature is 230 ° C, the treatment time is 30 minutes (minutes).

[0048] (5) Dry heat shrinkage: The heat treatment temperature is 180°C and measured in accordance with FZ / T50004.

[0049] (6) Boiling water shrinkage: Measured according to GB / 6505-2008 "Heat shrinkage test method for artificial filament yarn". Specifically, take a piece of polyamide industrial yarn, apply a tension of 0.05±0.005cN / dtex in advance, mark two points 50.00cm apart, wrap it in gauze, place it in boiling water and boil for 30 minutes, then dry the sample, measure the length between the two marks, and calculate the boiling water shrinkage using the following formula: Boiling water shrinkage rate = ((initial length - length after shrinkage) / initial length)*100%

[0050] (7) Relative Viscosity: The relative viscosity of the deoiled polyamide yarn (unfinished raw spun yarn) and the relative viscosity of the resin are measured using an Ubbelohde viscometer by the concentrated sulfuric acid method according to the following procedure: Accurately weigh out 0.25±0.0002 g of dried polyamide resin sample or its staple fiber, add 50 mL of concentrated sulfuric acid (96%) for dissolution, and measure and record the flow time t0 of the concentrated sulfuric acid and the flow time t of the sample solution of polyamide 56 chips or staple fiber in a constant temperature water bath at 25°C. The relative viscosity is calculated according to the following formula: Relative viscosity VN=t / t0; t represents the flow time of the solution, and t0 represents the flow time of the solvent.

[0051] (8) Moisture content: measured by Karl Fischer titrator. (9) Crystallinity and orientation: Using a Rigaku Corporation (Japan) D / max-2550PC X-ray diffractometer, a Cu target wavelength

number

[0052] The following formula is used to calculate the crystallinity:

number

number

number

[0053] The degree of orientation is calculated using the following formula:

number

[0054] (10) Manufacturing yield: Production yield = ((total amount of resin charged - amount of finished product) / total amount of resin charged)*100% (11) Number average molecular weight: measured by standard GPC. (12) Molecular weight distribution: measured by gel permeation chromatography (GPC).

[0055] (13) Oligomer content test: Measured by water extraction method (gravimetric) as follows: Accurately weigh about 8g of polyamide 56 resin dried at 130℃ for 7 hours and place in a 500mL round bottom flask. Add 400g of water. Reflux in a heating mantle for 36 hours, then decant the solution. Dry the particles in a weighing beaker at 130℃ for 7 hours, then seal in an aluminum plastic bag, cool and weigh. The weight loss is calculated. The polyamide 56 resin is prepared according to the method disclosed in CN108503826A and CN108503824A and has a relative viscosity of 2.7-4.5.

[0056] (14) Amino content: Measured using an automatic titrator. (15) Filament breakage: Manually count the number of filament breakages during spinning.

[0057] (16) Production yield: The weight percentage of industrial yarn obtained after spinning based on the weight of resin charged.

[0058] In the following Examples and Comparative Examples, the absolute value of the difference between the relative viscosity of the deoiled yarn and the relative viscosity of its raw material resin, the absolute value of the difference between the amino content of the deoiled yarn and the amino content of its raw material resin, filament breakage (times / 24 hr) and production yield (%) are shown in Table 1. The properties of the obtained polyamide 56 industrial yarn are shown in Table 2.

[0059] Example 1: Polyimide 56 industrial yarn (933dtex / 140f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were mixed uniformly under nitrogen conditions, and copper acetate was added as a heat stabilizer in an amount of 200 ppm based on the total weight of the raw materials to obtain a 60% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.05:1;

[0060] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.2 MPa, degas, maintain the pressure by keeping the temperature of the reaction system at 265°C at the end of the pressure maintenance, reduce the pressure of the reaction system to 0.1 MPa by keeping the temperature of the reaction system at 275°C at the end of the pressure reduction, reduce the pressure of the reaction system to 0.1 MPa by keeping the temperature at 285°C at the end of the evacuation, and evacuate to a vacuum of -0.05 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures;

[0061] (3) The low-viscosity polyamide 56 resin is solid-phase tackified to prepare a high-viscosity polyamide 56 resin; the temperature of solid-phase tackification is 155°C, the drying time is 20 hours, the relative viscosity of the low-viscosity polyamide 56 resin in 96% sulfuric acid is 2.4, the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid is 3.3, the oligomer content is 0.8% by weight, the number average molecular weight is 30,000, the molecular weight distribution is 1.6, the water content is 400 ppm, and the amino content is 36.5 mmol / kg.

[0062] 2. Spinning: (1) A high-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was performed in a screw extruder; the screw extruder included five heating zones, in particular, the first zone had a temperature of 255°C, the second zone had a temperature of 270°C, the third zone had a temperature of 280°C, the fourth zone had a temperature of 290°C, and the fifth zone had a temperature of 300°C; the polyamide 56 melt was ejected through a spinneret plate of a spinning beam to form a spun raw yarn; the temperature of the spinning beam was 290°C, the pack pressure was 15MPa, and the spinneret draw ratio was 150;

[0063] (2) The raw spun yarn is insulated, cooled, spin-finished, drawn, and wound into shape to obtain polyamide 56 industrial yarn; The insulation was performed using an annealing device, annealing temperature 220°C, annealing length 20 mm; Cooling was achieved with quench air, with an air velocity of 1.2 m / s, air temperature of 22° C. and humidity of 70%.

[0064] The drawing was performed in four stages, including: first, a step of feeding the spun raw yarn through a godet roller to a first pair of hot rollers, a step of performing a first stage of drawing between the first pair of hot rollers and a second pair of hot rollers, a step of performing a second stage of drawing between the second pair of hot rollers and a third pair of hot rollers, a step of performing a third stage of drawing and a first stage of heat setting between the third pair of hot rollers and a fourth pair of hot rollers, and a step of performing a fourth stage of drawing and a second stage of heat setting between the fourth pair of hot rollers and a fifth pair of hot rollers, with a total draw ratio of 5.0, a heat setting temperature of the first stage being 220° C., and a heat setting temperature of the second stage being 230° C. The winding tension when winding the raw yarn into a shape was 90 cN; the winding speed was 3500 m / min; and the winding overfeed ratio was 2%.

[0065] Example 2: Polyamide 56 industrial yarn (830 dtex / 192 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were mixed uniformly under nitrogen conditions, and copper acetate was added as a heat stabilizer in an amount of 500 ppm based on the total weight of the raw materials to obtain a 60% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.1:1;

[0066] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.3 MPa, degas, maintain the pressure at 255°C when the pressure is maintained, reduce the pressure of the reaction system to 0 MPa when the pressure is reduced to 265°C, and reduce the temperature of the reaction system to 275°C when the exhaust is completed, and evacuate to a vacuum of -0.08 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures;

[0067] (3) Low-viscosity polyamide 56 resin is solid-phase tackified to prepare high-viscosity polyamide 56 resin; the temperature of solid-phase tackification is 160°C, the drying time is 18 hours, the relative viscosity of the low-viscosity polyamide 56 resin in 96% sulfuric acid is 2.5, the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid is 3.5, the oligomer content is 0.6 wt%, the number average molecular weight is 33,000, the molecular weight distribution is 1.5, the water content is 450 ppm, and the amino content is 33.5 mmol / kg.

[0068] 2. Spinning: (1) A high-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was performed in a screw extruder; the screw extruder included five heating zones, in particular, the first zone had a temperature of 265°C, the second zone had a temperature of 275°C, the third zone had a temperature of 285°C, the fourth zone had a temperature of 295°C, and the fifth zone had a temperature of 305°C; the polyamide 56 melt was ejected through a spinneret plate of a spinning beam to form a spun raw yarn; the temperature of the spinning beam was 295°C, the pack pressure was 18MPa, and the spinneret draw ratio was 180;

[0069] (2) The raw spun yarn was insulated, cooled, spun-finished, drawn, and wound into shape to obtain polyamide 56 industrial yarn; insulation was performed with an annealing device, annealing temperature was 230°C, and annealing length was 30 mm; cooling was performed with annealing air, the air velocity was 0.8 m / s, the air temperature was 23°C, and the humidity was 75%; the winding tension when winding the raw spun yarn into shape was 80 cN; the winding speed was 3,000 m / min; and the winding overfeed ratio was 3%. The stretching process was the same four stage stretching process as in Example 1, except that the total stretch ratio was 4.8, the first stage heat set temperature was 225°C, and the second stage heat set temperature was 240°C.

[0070] Example 3: Polyamide 56 industrial yarn (550 dtex / 96 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were mixed uniformly under nitrogen conditions, and cuprous iodide was added as a heat stabilizer in an amount of 150 ppm based on the total weight of the raw materials to obtain a 65% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.1:1;

[0071] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.3 MPa, degas, maintain the pressure at 240°C when the pressure is maintained, reduce the pressure of the reaction system to 0.1 MPa when the pressure is reduced to 270°C, and reduce the pressure of the reaction system to 0.1 MPa when the pressure is reduced to 280°C when the evacuation is completed, and evacuate to a vacuum of -0.05 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures;

[0072] (3) A low-viscosity polyamide 56 resin is solid-phase tackified to prepare a high-viscosity polyamide 56 resin; the solid-phase tackification temperature is 160°C, and the drying time is 22 hours; The relative viscosity of the low-viscosity polyamide 56 resin in 96% sulfuric acid was 2.6, and the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid was 3.0, the oligomer content was 0.8 wt%, the number average molecular weight was 30,000, the molecular weight distribution was 1.6, the water content was 400 ppm, and the amino content was 42.5 mmol / kg.

[0073] 2. Spinning: (1) A high-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was performed by a screw extruder; the screw extruder was specifically divided into five heating zones, the first zone having a temperature of 248°C, the second zone having a temperature of 263°C, the third zone having a temperature of 276°C, the fourth zone having a temperature of 285°C, and the fifth zone having a temperature of 293°C; the polyamide 56 melt was ejected through a spinneret plate of a spinning beam to form a spun raw yarn; the temperature of the spinning beam was 285°C, the pressure of the pack was 16 MPa, and the draw ratio of the spinneret was 100;

[0074] (2) The raw spun yarn was insulated, cooled, spun finished, drawn, and wound into shape to obtain polyamide 56 industrial yarn; insulation was performed with an annealing device, annealing temperature 220°C, annealing length 25 mm; cooling was performed with quenching air, air speed 1.4 m / s, air temperature 22°C, humidity 65%; winding tension during winding of the raw spun yarn into shape was 55 cN; winding speed was 2,800 m / min; and winding overfeed ratio was 2.5%. The drawing process was the same four-stage drawing process as in Example 1, except that the total draw ratio was 5.0, the first stage heat setting temperature was 220°C, and the second stage heat setting temperature was 235°C.

[0075] Example 4: Polyamide 56 industrial yarn (550 dtex / 96 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were mixed uniformly under nitrogen conditions, and cuprous iodide was added as a heat stabilizer in an amount of 250 ppm based on the total weight of the raw materials to obtain a 65% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.12:1;

[0076] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.4 MPa, degas, maintain the pressure at 245°C when the pressure is maintained, reduce the pressure of the reaction system to 0.1 MPa when the pressure is reduced to 275°C, and reduce the pressure of the reaction system to 0.1 MPa when the pressure is reduced to 280°C when the evacuation is completed, and evacuate to a vacuum of -0.07 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures;

[0077] (3) Low-viscosity polyamide 56 resin is solid-phase tackified to prepare high-viscosity polyamide 56 resin; the temperature of solid-phase tackification is 150°C, the drying time is 25 hours, the relative viscosity of the low-viscosity polyamide 56 resin in 96% sulfuric acid is 2.55, the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid is 2.9, the oligomer content is 0.8% by weight, the number average molecular weight is 28,000, the molecular weight distribution is 1.5, the water content is 300 ppm, and the amino content is 40.5 mmol / kg.

[0078] 2. Spinning: (1) A high-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was heated in a screw extruder; the screw extruder was specifically divided into five heating zones, the first zone having a temperature of 245°C, the second zone having a temperature of 260°C, the third zone having a temperature of 270°C, the fourth zone having a temperature of 285°C, and the fifth zone having a temperature of 290°C; the polyamide 56 melt was ejected through a spinneret plate of a spinning beam to form a spun raw yarn; the temperature of the spinning beam was 280°C, the pack pressure was 10MPa, and the spinneret draw ratio was 200;

[0079] (2) The raw spun yarn was insulated, cooled, spun finished, drawn, and wound into shape to obtain polyamide 56 industrial yarn; insulation was performed with an annealing device, annealing temperature 210°C, annealing length 25mm; cooling was performed with quenching air, air speed 1.3m / s, air temperature 24°C, humidity 65%; winding tension during winding of raw spun yarn into shape was 55cN; winding speed was 2,600m / min; and winding overfeed ratio was 2.5%. The drawing process was the same four-stage drawing process as in Example 1, except that the total draw ratio was 5.3, the first stage heat setting temperature was 225°C, and the second stage heat setting temperature was 235°C.

[0080] Example 5: Polyamide 56 industrial yarn (233 dtex / 36 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were mixed uniformly under nitrogen conditions, and cuprous iodide was added as a heat stabilizer in an amount of 400 ppm based on the total weight of the raw materials to obtain a 65% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.05:1;

[0081] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.0 MPa, degas, maintain the pressure at 260°C when the pressure is maintained, reduce the pressure of the reaction system to 0.1 MPa when the pressure is reduced to 275°C, and reduce the pressure of the reaction system to 0.1 MPa when the pressure is reduced to 295°C when the evacuation is completed, and evacuate to a vacuum of -0.08 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures;

[0082] (3) preparing a high viscosity polyamide 56 resin by solid-phase tackification of a low viscosity polyamide 56 resin; the solid-phase tackification temperature is 155°C, and the drying time is 25 hours; The relative viscosity of the low-viscosity polyamide 56 resin in 96% sulfuric acid was 2.45, and the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid was 3.6, the oligomer content was 1.0 wt%, the number average molecular weight was 36,000, the molecular weight distribution was 1.7, the water content was 350 ppm, and the amino content was 46.5 mmol / kg.

[0083] 2. Spinning: (1) A high-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was heated in a screw extruder; the screw extruder was specifically divided into five heating zones, the first zone having a temperature of 255°C, the second zone having a temperature of 275°C, the third zone having a temperature of 280°C, the fourth zone having a temperature of 295°C, and the fifth zone having a temperature of 310°C; the polyamide 56 melt was ejected through a spinneret plate of a spinning beam to form a spun raw yarn; the temperature of the spinning beam was 295°C, the pack pressure was 19MPa, and the spinneret draw ratio was 250;

[0084] (2) The raw spun yarn was insulated, cooled, spun finished, drawn, and wound into shape to obtain polyamide 56 industrial yarn; insulation was performed with an annealing device, annealing temperature 220°C, annealing length 20 mm; cooling was performed with quenching air, air speed 1.0 m / s, air temperature 18°C, humidity 70%; winding tension during winding of the raw spun yarn into shape was 23 cN; winding speed was 2,900 m / min; and winding overfeed ratio was 1.5%. The drawing process was the same four-stage drawing process as in Example 1, except that the total draw ratio was 5.5, the first stage heat setting temperature was 230°C, and the second stage heat setting temperature was 230°C.

[0085] Example 6: Polyamide 56 industrial yarn (1,670 dtex / 192 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were uniformly mixed under nitrogen conditions, and a heat stabilizer was added to obtain a 65% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.1:1; the heat stabilizer was a complex of copper acetate and potassium iodide, in which copper acetate was added in an amount of 200 ppm based on the total weight of the raw materials, and potassium iodide was added in an amount of 500 ppm based on the total weight of the raw materials.

[0086] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.3 MPa, degas, maintain the pressure at 255°C when the pressure is maintained, reduce the pressure of the reaction system to 0.1 MPa when the pressure is reduced to 270°C, and reduce the pressure of the reaction system to 0.1 MPa when the pressure is reduced to 280°C when the evacuation is completed, and evacuate to a vacuum of -0.01 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures;

[0087] (3) preparing a high viscosity polyamide 56 resin by solid-phase tackification of a low viscosity polyamide 56 resin; the solid-phase tackification temperature is 155°C, and the drying time is 30 hours; The relative viscosity of the low-viscosity polyamide 56 resin in 96% sulfuric acid was 2.7, and the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid was 3.8, the oligomer content was 0.8 wt%, the number average molecular weight was 38,000, the molecular weight distribution was 1.5, the water content was 500 ppm, and the amino content was 42.5 mmol / kg.

[0088] 2. Spinning: (1) A high-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was heated in a screw extruder; the screw extruder was specifically divided into five heating zones, the first zone having a temperature of 250°C, the second zone having a temperature of 275°C, the third zone having a temperature of 280°C, the fourth zone having a temperature of 295°C, and the fifth zone having a temperature of 305°C; the polyamide 56 melt was ejected through a spinneret plate of a spinning beam to form a spun raw yarn; the temperature of the spinning beam was 290°C, the pack pressure was 14 MPa, and the spinneret draw ratio was 120;

[0089] (2) The raw spun yarn was insulated, cooled, spun finished, drawn, and wound into shape to obtain polyamide 56 industrial yarn; insulation was performed with an annealing device, annealing temperature 230°C, annealing length 40 mm; cooling was performed with quenching air, air speed 1.1 m / s, air temperature 23°C, humidity 75%; winding tension during winding of the raw spun yarn into shape was 160 cN; winding speed was 3,200 m / min; and winding overfeed ratio was 3.5%. The drawing process was the same four-stage drawing process as in Example 1, except that the total draw ratio was 5.6, the first stage heat setting temperature was 225°C, and the second stage heat setting temperature was 235°C.

[0090] Example 7: Polyamide 56 industrial yarn (2,800 dtex / 480 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were uniformly mixed under nitrogen conditions, and a heat stabilizer was added to obtain a 65% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.05:1; the heat stabilizer was a complex of copper acetate and potassium iodide, where copper acetate was added in an amount of 250 ppm based on the total weight of the raw materials, and potassium iodide was added in an amount of 2000 ppm based on the total weight of the raw materials.

[0091] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.2 MPa, degas, maintain the pressure by keeping the temperature of the reaction system at 260°C at the end of the pressure maintenance, reduce the pressure of the reaction system to 0.1 MPa by keeping the temperature of the reaction system at 285°C at the end of the pressure reduction, reduce the pressure of the reaction system to 0.1 MPa by keeping the temperature at 290°C at the end of the evacuation, and evacuate to a vacuum of -0.03 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures;

[0092] (3) preparing a high viscosity polyamide 56 resin by solid-phase tackification of a low viscosity polyamide 56 resin; the solid-phase tackification temperature is 155°C, and the drying time is 30 hours; The relative viscosity of the low-viscosity polyamide 56 resin in 96% sulfuric acid was 2.35, and the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid was 3.2, the oligomer content was 0.8 wt%, the number average molecular weight was 32,000, the molecular weight distribution was 1.5, the water content was 450 ppm, and the amino content was 38.5 mmol / kg.

[0093] 2. Spinning: (1) A high-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was performed by a screw extruder; the screw extruder was specifically divided into five heating zones, the first zone having a temperature of 258°C, the second zone having a temperature of 276°C, the third zone having a temperature of 288°C, the fourth zone having a temperature of 298°C, and the fifth zone having a temperature of 305°C; the polyamide 56 melt was ejected through a spinneret plate of a spinning beam to form a spun raw yarn; the temperature of the spinning beam was 293°C, the pack pressure was 12MPa, and the spinneret draw ratio was 160;

[0094] (2) The raw spun yarn was insulated, cooled, spun-finished, drawn, and wound into shape to obtain polyamide 56 industrial yarn; insulation was performed with an annealing device, annealing temperature 230°C, and annealing length 20 mm; cooling was performed with annealing air, air velocity 1.2 m / s, air temperature 23°C, and humidity 70%; the winding tension when winding the raw spun yarn into shape was 280 cN; the winding speed was 2,700 m / min; and the winding overfeed ratio was 3%.

[0095] The stretching process was the same four stage stretching process as in Example 1, except that the total stretch ratio was 4.8, the first stage heat set temperature was 220°C, and the second stage heat set temperature was 230°C.

[0096] Example 8: Polyamide 56 industrial yarn (233 dtex / 36 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were uniformly mixed under nitrogen conditions, and a heat stabilizer was added to obtain a 65% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.05:1; the heat stabilizer was a complex of copper acetate and potassium iodide, where copper acetate was added in an amount of 150 ppm based on the total weight of the raw materials, and potassium iodide was added in an amount of 800 ppm based on the total weight of the raw materials.

[0097] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.2 MPa, degas, maintain the pressure at 260°C when the pressure is maintained, reduce the pressure of the reaction system to 0.1 MPa when the pressure is reduced to 285°C, and reduce the pressure of the reaction system to 0.1 MPa when the pressure is reduced to 290°C when the evacuation is completed, and evacuate to a vacuum of -0.01 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures;

[0098] (3) preparing a high viscosity polyamide 56 resin by solid-phase tackification of a low viscosity polyamide 56 resin; the solid-phase tackification temperature is 155°C, and the drying time is 30 hours; The relative viscosity of the low-viscosity polyamide 56 resin in 96% sulfuric acid was 2.4, and the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid was 3.4, the oligomer content was 0.8 wt%, the number average molecular weight was 33,000, the molecular weight distribution was 1.6, the water content was 550 ppm, and the amino content was 33.5 mmol / kg.

[0099] 2. Spinning: (1) A high-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was heated in a screw extruder; the screw extruder was specifically divided into five heating zones, the first zone having a temperature of 268°C, the second zone having a temperature of 280°C, the third zone having a temperature of 290°C, the fourth zone having a temperature of 295°C, and the fifth zone having a temperature of 303°C; the polyamide 56 melt was ejected through a spinneret plate of a spinning beam to form a spun raw yarn; the temperature of the spinning beam was 298°C, the pack pressure was 18MPa, and the spinneret draw ratio was 120;

[0100] (2) The raw spun yarn was insulated, cooled, spun-finished, drawn, and wound into shape to obtain polyamide 56 industrial yarn; insulation was performed with an annealing device, annealing temperature was 220°C, and annealing length was 30 mm; cooling was performed with annealing air, the air velocity was 1.2 m / s, the air temperature was 23°C, and the humidity was 70%; the winding tension when winding the raw spun yarn into shape was 140 cN; the winding speed was 3,000 m / min; and the winding overfeed ratio was 2%.

[0101] The stretching process was the same four stage stretching process as in Example 1, except that the total stretch ratio was 4.8, the first stage heat set temperature was 220°C, and the second stage heat set temperature was 230°C.

[0102] Example 9: Polyamide 56 industrial yarn (933 dtex / 140 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were mixed uniformly under nitrogen conditions, and copper chloride was added as a heat stabilizer in an amount of 300 ppm based on the total weight of the raw materials to obtain a 65% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.1:1;

[0103] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.25 MPa, degas, maintain the pressure by keeping the temperature of the reaction system at 260°C at the end of the pressure maintenance, reduce the pressure of the reaction system to 0.1 MPa by keeping the temperature of the reaction system at 275°C at the end of the pressure reduction, reduce the pressure of the reaction system to 0.1 MPa by keeping the temperature at 280°C at the end of the evacuation, and evacuate to a vacuum of -0.01 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures;

[0104] (3) A low-viscosity polyamide 56 resin is solid-phase tackified to prepare a high-viscosity polyamide 56 resin; the solid-phase tackification temperature is 160°C, and the drying time is 22 hours; The relative viscosity of the low-viscosity polyamide 56 resin in 96% sulfuric acid was 2.4, and the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid was 3.4, the oligomer content was 0.8 wt%, the number average molecular weight was 33,000, the molecular weight distribution was 1.6, the water content was 550 ppm, and the amino content was 33.5 mmol / kg.

[0105] 2. Spinning: (1) A high-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was heated in a screw extruder; the screw extruder was specifically divided into five heating zones, the first zone having a temperature of 268°C, the second zone having a temperature of 280°C, the third zone having a temperature of 290°C, the fourth zone having a temperature of 295°C, and the fifth zone having a temperature of 303°C; the polyamide 56 melt was ejected through a spinneret plate of a spinning beam to form a spun raw yarn; the temperature of the spinning beam was 280°C, the pack pressure was 13MPa, and the spinneret draw ratio was 150;

[0106] (2) The raw spun yarn was insulated, cooled, spun-finished, drawn, and wound into shape to obtain polyamide 56 industrial yarn; insulation was performed with an annealing device, annealing temperature was 200°C, and annealing length was 40 mm; cooling was performed with annealing air, the air velocity was 1.3 m / s, the air temperature was 20°C, and the humidity was 70%; the winding tension when winding the raw spun yarn into shape was 90 cN; the winding speed was 2,700 m / min; and the winding overfeed ratio was 2.5%.

[0107] The stretching process was the same four stage stretching process as in Example 1, except that the total stretch ratio was 4.8, the first stage heat set temperature was 210°C, and the second stage heat set temperature was 220°C.

[0108] Example 10: Polyamide 56 industrial yarn (933 dtex / 140 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were uniformly mixed under nitrogen conditions to obtain a 65% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.15:1;

[0109] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.3 MPa, degas it, maintain the pressure by keeping the temperature of the reaction system at 265°C at the end of the pressure maintenance, reduce the pressure of the reaction system to 0 MPa by keeping the temperature of the reaction system at 275°C at the end of the pressure reduction, and evacuate to a vacuum of -0.04 MPa with a temperature of 285°C at the end of the evacuation to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures; The heat stabilizer masterbatch was injected online before the polymer melt was pelletized, the copper ion content in the heat stabilizer masterbatch was 2.0 wt%, the addition amount of the heat stabilizer masterbatch was 1.5 wt%, the heat stabilizer masterbatch substrate was polyamide 56, and the preparation method of the heat stabilizer masterbatch included the following steps: (a) vacuum-dried the substrate polyamide 56 and then ground into powder, the polyamide 56 was 65 parts by mass, its relative viscosity was 2.9, its number average molecular weight was 24 kg / mol, its molecular weight distribution was 2.1, and its moisture content was 500 ppm; (b) The powder obtained in step (a) is mixed with 12.5 parts by weight of heat stabilizer cuprous iodide, 0.5 parts by weight of lubricant wax OP, and 0.2 parts by weight of antioxidant 168, and melted, and the mixture is extruded by twin screw and pelletized to obtain a heat stabilizer master batch, where the processing temperature of each zone is set as follows: the temperature of the first zone is 251°C, the temperature of the second zone is 264°C, the temperature of the third zone is 269°C, the temperature of the fourth zone is 273°C, the temperature of the fifth zone is 276°C, the screw rotation speed is 250r / min, and the filter screen is 150 mesh.

[0110] (3) preparing a high viscosity polyamide 56 resin by solid-phase tackification of a low viscosity polyamide 56 resin; the solid-phase tackification temperature is 155°C, and the drying time is 25 hours; The relative viscosity of the low-viscosity polyamide 56 resin in 96% sulfuric acid was 2.5, and the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid was 3.7, the oligomer content was 0.6 wt%, the number average molecular weight was 34,000, the molecular weight distribution was 1.5, the water content was 300 ppm, and the amino content was 33.8 mmol / kg.

[0111] 2. Spinning: (1) A high-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was performed by a screw extruder; the screw extruder was specifically divided into five heating zones, the first zone having a temperature of 265°C, the second zone having a temperature of 278°C, the third zone having a temperature of 288°C, the fourth zone having a temperature of 295°C, and the fifth zone having a temperature of 300°C; the polyamide 56 melt was ejected through a spinneret plate of a spinning beam to form a spun raw yarn; the temperature of the spinning beam was 295°C, the pressure of the pack was 14 MPa, and the draw ratio of the spinneret was 80;

[0112] (2) The raw spun yarn is insulated, cooled, spun, drawn, and wound into a shape to obtain polyamide 56 industrial yarn; insulation is performed using an annealing device, annealing temperature is 230°C, and annealing length is 25 mm; cooling is performed using quenching air, air velocity is 1.1 m / s, air temperature is 22°C, and humidity is 70%; The winding tension when winding the spun raw yarn into shape was 90 cN; the winding speed was 2,600 m / min; and the winding overfeed ratio was 2%.

[0113] The stretching process was the same four stage stretching process as in Example 1, except that the total stretch ratio was 5.0, the first stage heat set temperature was 220°C, and the second stage heat set temperature was 230°C.

[0114] Example 11: Polyamide 56 industrial yarn (933 dtex / 140 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were uniformly mixed under nitrogen conditions to obtain a 65% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.06:1;

[0115] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.2 MPa, degas, maintain the pressure by keeping the temperature of the reaction system at 265°C at the end of the pressure maintenance, reduce the pressure of the reaction system to 0.1 MPa by keeping the temperature of the reaction system at 275°C at the end of the pressure reduction, reduce the pressure of the reaction system to 0.1 MPa by keeping the temperature at 285°C at the end of the evacuation, and evacuate to a vacuum of -0.06 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures;

[0116] (3) The low-viscosity polyamide 56 resin is solid-phase tackified to prepare a high-viscosity polyamide 56 resin; the temperature of solid-phase tackification is 160°C, the drying time is 28 hours, the relative viscosity of the low-viscosity polyamide 56 resin in 96% sulfuric acid is 2.4, the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid is 3.3, the oligomer content is 0.9 wt%, the number average molecular weight is 32,000, the molecular weight distribution is 1.6, the water content is 450 ppm, and the amino content is 36.5 mmol / kg.

[0117] 2. Spinning: (1) A high-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was heated in a screw extruder; the screw extruder was specifically divided into five heating zones, the first zone having a temperature of 255°C, the second zone having a temperature of 275°C, the third zone having a temperature of 280°C, the fourth zone having a temperature of 290°C, and the fifth zone having a temperature of 305°C; the polyamide 56 melt was ejected through a spinneret plate of a spinning beam to form a spun raw yarn; the temperature of the spinning beam was 295°C, the pack pressure was 14MPa, and the spinneret draw ratio was 140; The heat stabilizer masterbatch was blended by a masterbatch adding device during spinning, the copper ion content of the heat stabilizer masterbatch was 1.8 wt %, and the heat stabilizer masterbatch was added at 1.2 wt %. The preparation method of the heat stabilizer masterbatch was the same as that of Example 10.

[0118] (2) The raw spun yarn is insulated, cooled, spun, drawn, and wound into a shape to obtain polyamide 56 industrial yarn; insulation is performed using an annealing device, annealing temperature is 240°C, and annealing length is 20 mm; cooling is performed with quenching air, air velocity is 1.4 m / s, air temperature is 22°C, and humidity is 70%; The winding tension when winding the spun raw yarn into shape was 90 cN; the winding speed was 3,500 m / min; and the winding overfeed ratio was 2%.

[0119] The stretching process was the same four stage stretching process as in Example 1, except that the total stretch ratio was 5.0, the first stage heat set temperature was 220°C, and the second stage heat set temperature was 230°C.

[0120] Example 12: Polyamide 56 industrial yarn (933 dtex / 140 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were uniformly mixed under nitrogen conditions to obtain a 65% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.08:1;

[0121] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.2 MPa, degas, maintain the pressure at 265°C when the pressure is maintained, reduce the pressure of the reaction system to 0 MPa when the pressure is reduced to 275°C, and reduce the temperature of the reaction system to 290°C when the exhaust is completed, and evacuate to a vacuum of -0.05 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures;

[0122] (3) The low-viscosity polyamide 56 resin is solid-phase tackified to prepare a high-viscosity polyamide 56 resin; the temperature of solid-phase tackification is 160°C, the drying time is 28 hours, the relative viscosity of the low-viscosity polyamide 56 resin in 96% sulfuric acid is 2.4, the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid is 3.2, the oligomer content is 0.8% by weight, the number average molecular weight is 30,000, the molecular weight distribution is 1.6, the water content is 400 ppm, and the amino content is 32.3 mmol / kg.

[0123] 2. Spinning: (1) A high-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was heated in a screw extruder; the screw extruder was specifically divided into five heating zones, the first zone having a temperature of 250°C, the second zone having a temperature of 270°C, the third zone having a temperature of 285°C, the fourth zone having a temperature of 290°C, and the fifth zone having a temperature of 290°C; the polyamide 56 melt was ejected through a spinneret plate of a spinning beam to form a spun raw yarn; the temperature of the spinning beam was 285°C, the pressure of the pack was 12MPa, and the draw ratio of the spinneret was 180; The heat stabilizer masterbatch was blended in a masterbatch addition device during spinning, and the copper ion content of the heat stabilizer masterbatch was 1.6 wt %, and the heat stabilizer masterbatch was added at 1.5 wt %; The heat stabilizer masterbatch substrate was polyamide 6, and the preparation method of the heat stabilizer masterbatch included the following steps: (a) vacuum-dried the substrate polyamide 6 and then ground into powder, the polyamide 6 was 65 parts by mass, its relative viscosity was 2.9, its number average molecular weight was 24 kg / mol, its molecular weight distribution was 2.1, and its moisture content was 500 ppm; (b) The powder obtained in step (a) is mixed with 15 parts by weight of heat stabilizer cuprous iodide, 0.5 parts by weight of lubricant wax OP, and 0.2 parts by weight of antioxidant 168, melted, and the mixture is extruded by a twin screw and pelletized to obtain a heat stabilizer master batch, where the processing temperature of each zone is set as follows: the temperature of the first zone is 200°C, the temperature of the second zone is 210°C, the temperature of the third zone is 220°C, the temperature of the fourth zone is 230°C, and the temperature of the fifth zone is 235°C, the screw rotation speed is 250r / min, and the filter screen is 150 mesh.

[0124] (2) The raw spun yarn is insulated, cooled, spun, drawn, and wound into a shape to obtain polyamide 56 industrial yarn; insulation is performed using an annealing device, annealing temperature is 225°C, and annealing length is 20 mm; cooling is performed with quenching air, air velocity is 1.2 m / s, air temperature is 22°C, and humidity is 70%; The winding tension when winding the spun raw yarn into shape was 90 cN; the winding speed was 3,300 m / min; and the winding overfeed ratio was 2%.

[0125] The stretching process was the same four stage stretching process as in Example 1, except that the total stretch ratio was 5.0, the first stage heat set temperature was 220°C, and the second stage heat set temperature was 230°C.

[0126] Example 13: Polyamide 56 industrial yarn (933 dtex / 140 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were mixed uniformly under nitrogen conditions, and cuprous iodide was added as a heat stabilizer in an amount of 200 ppm based on the total weight of the raw materials to obtain a 65% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.1:1;

[0127] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.25 MPa, degas, maintain the pressure by keeping the temperature of the reaction system at 265°C at the end of the pressure maintenance, reduce the pressure of the reaction system to 0.1 MPa by keeping the temperature of the reaction system at 280°C at the end of the pressure reduction, reduce the pressure of the reaction system to 0.1 MPa by keeping the temperature at 295°C at the end of the evacuation, and evacuate to a vacuum of -0.01 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures; The high viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 3.4, an oligomer content of 0.8 wt%, a number average molecular weight of 30,000, a molecular weight distribution of 1.6, a water content of 400 ppm, and an amino content of 32.5 mmol / kg.

[0128] 2. Spinning: (1) The high-viscosity polyamide 56 melt was transported to the spinning beam by the melt booster pump and directly spun; the polyamide 56 melt was ejected through the spinneret plate of the spinning beam to form a spun raw yarn; where the temperature of the spinning beam was 280°C, the pressure of the pack was 18MPa, and the draw ratio of the spinneret was 200;

[0129] (2) The raw spun yarn is insulated, cooled, spun, drawn, and wound into a shape to obtain polyamide 56 industrial yarn; insulation is performed using an annealing device, annealing temperature is 220°C, and annealing length is 20 mm; cooling is performed with quenching air, air velocity is 1.2 m / s, air temperature is 22°C, and humidity is 70%; The winding tension when winding the spun raw yarn into shape was 90 cN; the winding speed was 2,500 m / min; and the winding overfeed ratio was 2%.

[0130] The stretching process was the same four stage stretching process as in Example 1, except that the total stretch ratio was 5.0, the first stage heat set temperature was 220°C, and the second stage heat set temperature was 230°C.

[0131] Example 14: Polyamide 56 industrial yarn (2,800 dtex / 480 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were uniformly mixed under nitrogen conditions, and a heat stabilizer was added to obtain a 65% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.08:1; the heat stabilizer was a complex of copper acetate and potassium iodide, where copper acetate was added in an amount of 200 ppm based on the total weight of the raw materials, and potassium iodide was added in an amount of 700 ppm based on the total weight of the raw materials.

[0132] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.4 MPa, degas, maintain the pressure by keeping the temperature of the reaction system at 265°C at the end of pressure maintenance, reduce the pressure of the reaction system to 0.1 MPa by keeping the temperature of the reaction system at 285°C at the end of pressure reduction, reduce the pressure of the reaction system to 290°C at the end of evacuation, and evacuate to a vacuum of -0.06 MPa to obtain a high-viscosity polyamide 56 melt; all pressures are gauge pressures; The high viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 3.5, an oligomer content of 1.0 wt%, a number average molecular weight of 34,000, a molecular weight distribution of 1.6, a water content of 450 ppm, and an amino content of 40.5 mmol / kg.

[0133] 2. Spinning: (1) The high-viscosity polyamide 56 melt was transported to the spinning beam by the melt booster pump and spun directly; the polyamide 56 melt was ejected through the spinneret plate of the spinning beam to form a spun raw yarn; where the temperature of the spinning beam was 290°C, the pressure of the pack was 12MPa, and the draw ratio of the spinneret was 180;

[0134] (2) The raw spun yarn is insulated, cooled, spun, drawn, and wound into a shape to obtain polyamide 56 industrial yarn; insulation is performed using an annealing device, annealing temperature is 210°C, and annealing length is 20 mm; cooling is performed using annealing air, air velocity is 1.2 m / s, air temperature is 23°C, and humidity is 70%; The winding tension when winding the spun raw yarn into shape was 280 cN; the winding speed was 2,900 m / min; and the winding overfeed ratio was 3%.

[0135] The stretching process was the same four stage stretching process as in Example 1, except that the total stretch ratio was 4.5, the first stage heat set temperature was 220°C, and the second stage heat set temperature was 230°C.

[0136] Example 15: Polyimide 56 industrial yarn (1,670 dtex / 192 f) The manufacturing method was the same as in Example 6, except that the heat stabilizer was a composite of copper acetate and potassium iodide, copper acetate was added in an amount of 200 ppm based on the total weight of the manufacturing raw materials, and potassium iodide was added in an amount of 1000 ppm based on the total weight of the manufacturing raw materials.

[0137] Example 16: Polyamide 56 industrial yarn (1,670 dtex / 192 f) The preparation method was the same as in Example 6, except that the heat stabilizer was a composite of copper acetate and potassium iodide, the copper acetate was added in an amount of 200 ppm based on the total weight of the raw materials, and the potassium iodide was added in an amount of 2000 ppm based on the total weight of the raw materials.

[0138] Example 17: Polyamide 56 industrial yarn (1,670 dtex / 192 f) The preparation method was the same as in Example 6, except that the heat stabilizer was a composite of copper acetate and potassium iodide, the copper acetate was added in an amount of 200 ppm based on the total weight of the raw materials, and the potassium iodide was added in an amount of 1800 ppm based on the total weight of the raw materials.

[0139] Example 18: Polyamide 56 industrial yarn (1,670 dtex / 192 f) The preparation method was the same as in Example 6, except that the heat stabilizer was a composite of copper acetate and potassium iodide, the copper acetate was added in an amount of 200 ppm based on the total weight of the raw materials, and the potassium iodide was added in an amount of 2500 ppm based on the total weight of the raw materials.

[0140] Comparative Example 1: Polyimide 56 industrial yarn (933dtex / 140f) The preparation method was the same as in Example 1, except that the heat stabilizer copper acetate was not added during the polymerization of 1,5-pentanediamine and adipic acid in step (1).

[0141] Comparative Example 2: Polyimide 56 industrial yarn (933dtex / 140f) The production method was the same as in Example 1, except that in the polymerization in step 1, the water content of the obtained high-viscosity polyamide 56 resin was 1200 ppm.

[0142] Comparative Example 3: Polyamide 56 industrial yarn (1,670 dtex / 192 f) The process included the following steps: 1. Polymerization: (1) The raw materials 1,5-pentanediamine, adipic acid and water were uniformly mixed under nitrogen conditions, and a heat stabilizer was added to obtain a 60% concentration polyamide 56 salt solution; the molar ratio of 1,5-pentanediamine to adipic acid was 1.1:1; the heat stabilizer was a complex of copper acetate and potassium iodide, in which copper acetate was added in an amount of 200 ppm based on the total weight of the raw materials, and potassium iodide was added in an amount of 500 ppm based on the total weight of the raw materials;

[0143] (2) Heat the polyamide 56 salt solution, increase the pressure of the reaction system to 2.3 MPa, degas, maintain the pressure at 255°C when the pressure is maintained, reduce the pressure of the reaction system to 0.1 MPa when the pressure is reduced to 270°C, and reduce the pressure of the reaction system to 0.1 MPa when the pressure is reduced to 280°C when the evacuation is completed, and evacuate to a vacuum of -0.05 MPa to obtain a low-viscosity polyamide 56 resin; all pressures are gauge pressures; The low viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.5, an oligomer content of 0.8 wt%, a number average molecular weight of 16,000, a molecular weight distribution of 1.5, a water content of 500 ppm, and an amino content of 42.5 mmol / kg.

[0144] 2. Spinning: (1) The low-viscosity polyamide 56 resin was heated to a molten state to form a polyamide 56 melt, which was heated in a screw extruder; the screw extruder was specifically divided into five heating zones, the first zone having a temperature of 250°C, the second zone having a temperature of 275°C, the third zone having a temperature of 280°C, the fourth zone having a temperature of 295°C, and the fifth zone having a temperature of 305°C; the polyamide 56 melt was ejected through the spinneret plate of the spinning beam to form a spun raw yarn; the temperature of the spinning beam was 290°C, the pack pressure was 14MPa, and the spinneret draw ratio was 120;

[0145] (2) The raw spun yarn is insulated, cooled, spin-finished, drawn, and wound into shape to obtain polyamide 56 industrial yarn; Insulation was performed with an annealing device, annealing temperature 230°C, and annealing length 40 mm; cooling was performed with quenching air, air velocity 1.1 m / s, air temperature 23°C, and humidity 75%; the winding tension when winding the raw spun yarn into shape was 160 cN; the winding speed was 3,200 m / min; and the winding overfeed ratio was 3.5%; the drawing process was the same four-stage drawing process as in Example 1, except that the total draw ratio was 5.6, the first stage heat setting temperature was 225°C, and the second stage heat setting temperature was 235°C.

[0146] Comparative Example 4: Polyamide 6 industrial yarn (933dtex / 140f) The process included the following steps: 1. A high-viscosity polyamide 6 resin was heated to a molten state to form a polyamide 6 melt, and the heating was carried out in a screw extruder; the screw extruder was specifically divided into five heating zones, the first zone having a temperature of 255°C, the second zone having a temperature of 270°C, the third zone having a temperature of 280°C, the fourth zone having a temperature of 290°C, and the fifth zone having a temperature of 300°C; The high-viscosity polyamide 6 resin in 96% sulfuric acid had a relative viscosity of 3.3, an oligomer content of 0.8 wt%, a number average molecular weight of 30,000, a molecular weight distribution of 1.6, a water content of 400 ppm, and an amino content of 36.5 mmol / kg.

[0147] 2. The polyamide 6 melt is ejected through the spinneret plate of the spinning beam to form a spinning raw yarn, and the polyamide 6 melt is spun into a yarn; the temperature of the spinning beam is 290°C, the pressure of the pack is 15MPa, and the draw ratio of the spinneret is 150;

[0148] 3. Processing the raw spun yarn to obtain polyamide 6 industrial yarn, where the processing includes the steps of insulating, cooling, spinning finishing, drawing, and winding the raw spun yarn into a shape to obtain polyamide 56 industrial yarn; insulation was performed using an annealing device, annealing temperature was 220℃, and annealing length was 20mm; cooling was performed using quenching air, air velocity was 1.2m / s, air temperature was 22℃, and humidity was 70%; The winding tension when winding the spun raw yarn into shape was 90 cN; the winding speed was 3,500 m / min; and the winding overfeed ratio was 2.0%.

[0149] The stretching process was the same four stage stretching process as in Example 1, except that the total stretch ratio was 5.0, the first stage heat set temperature was 220°C, and the second stage heat set temperature was 230°C.

[0150] In the above examples and comparative examples, the absolute value of the difference between the relative viscosity of the deoiled yarn and the relative viscosity of its raw material resin, the absolute value of the difference between the amino content of the deoiled yarn and the amino content of its raw material resin, filament breakage (times / 24 hours) and production yield (%) are shown in Table 1. The properties of the obtained polyamide 56 industrial yarn are shown in Table 2.

[0151] [Table 1]

[0152] In the present invention, the fluctuation range of the viscosity and amino content of the deoiled yarn was reduced, thereby improving the uniformity and stability of the polyamide 56 melt, reducing filament breakage, and improving spinnability. The polyamide 56 industrial yarn produced achieved a high yield of over 95%, with filament breakage occurring less than once per 24 hours.

[0153] [Table 2]

[0154] The present invention optimizes the viscosity, oligomer content, molecular weight and its distribution, and moisture content of polyamide 56 resin. Furthermore, the present invention optimizes the spinning process of polyamide 56 industrial yarn, improves its crystallinity and orientation, increases the set temperature and winding overfeed ratio, and reduces the subsequent stress relaxation. Thus, the present invention provides polyamide 56 industrial yarn with excellent mechanical properties and dimensional stability, including a breaking strength of 8.0 cN / dtex or more, a breaking elongation of 26% or less, a dry heat shrinkage rate and a boiling water shrinkage rate of 6% or less, a crystallinity of 70% or more, and an orientation rate of 80% or more.

[0155] The above description of the embodiments is provided to facilitate those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications to these embodiments are readily possible. The general principles described herein can be applied to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments. All improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims

1. Polyamide 56 industrial yarn, The polyamide 56 industrial yarn is characterized in that the raw materials for producing the polyamide 56 industrial yarn include at least a high viscosity polyamide 56 resin, the high viscosity polyamide 56 resin having a relative viscosity of 2.7 to 4.5 in 96% sulfuric acid, an oligomer content of 0.2 to 1.0% by weight, a number average molecular weight of 18,000 to 40,000, a molecular weight distribution of 0.8 to 1.8, a water content of 200 to 800 ppm, and an amino acid content of 20 to 50 mmol / kg, the polyamide 56 industrial yarn includes a heat stabilizer, the heat stabilizer includes one of copper acetate, potassium iodide, copper chloride, cuprous iodide, copper oxide, cuprous oxide, or a combination thereof, and the heat stabilizer is added in an amount of 10 to 2800 ppm based on the total weight of the raw materials for production.

2. The polyamide 56 industrial yarn according to claim 1, characterized in that the heat stabilizer is added in an amount of 100 to 2500 ppm relative to the total weight of the raw materials for production.

3. The polyamide 56 industrial yarn according to claim 1, characterized in that the heat stabilizer comprises a composition of potassium iodide and copper acetate, and the molar ratio of copper acetate to potassium iodide is 1:1 to 15.

4. The high-viscosity polyamide 56 resin has a relative viscosity of 3.2 to 4.0 in 96% sulfuric acid; and / or The high-viscosity polyamide 56 resin has an oligomer content of 0.4 to 0.6% by weight; and / or The high-viscosity polyamide 56 resin has a number-average molecular weight of 25,000 to 30,000 and a molecular weight distribution of 1.2 to 1.5; and / or The high-viscosity polyamide 56 resin has a water content of 300 to 750 ppm; and / or The polyamide 56 industrial yarn according to claim 1, characterized in that the high viscosity polyamide 56 resin has an amino acid content of 24 to 45 mmol / kg.

5. The polyamide 56 industrial yarn according to claim 1, characterized in that the copper ion content in the polyamide 56 resin is 10 to 1000 ppm.

6. The polyamide 56 industrial yarn according to any one of claims 1 to 5, characterized in that the polyamide 56 industrial yarn has a heat resistance to breaking strength retention rate of 90% or more after being treated at 180°C for 4 hours, and / or has a heat resistance to breaking strength retention rate of 90% or more after being treated at 230°C for 30 minutes, and / or the polyamide 56 industrial yarn has a dry heat shrinkage rate of 8.0% or less.

7. The polyamide 56 industrial yarn according to any one of claims 1 to 5, characterized in that the polyamide 56 industrial yarn has a heat resistance tensile strength retention rate of 93% or more after being treated at 180°C for 4 hours, and / or a heat resistance tensile strength retention rate of 92% or more after being treated at 230°C for 30 minutes, and / or the polyamide 56 industrial yarn has a dry heat shrinkage rate of 6.0% or less.

8. The aforementioned polyamide 56 industrial yarn has a breaking strength of 6.5 cN / dtex or more. The polyamide 56 industrial yarn has a boiling water shrinkage rate of 8.0% or less; and / or The polyamide 56 industrial yarn has a fineness of 100 to 3500 dtex; and / or The polyamide 56 industrial yarn has an elongation at break of 26% or less; and / or The polyamide 56 industrial yarn has a crystallinity of 70% or more; and / or The polyamide 56 industrial yarn according to any one of claims 1 to 5, characterized in that the polyamide 56 industrial yarn has an orientation degree of 80% or more.

9. A method for producing polyamide 56 industrial yarn according to any one of claims 1 to 8, wherein the method comprises the following steps: (1) A high-viscosity polyamide 56 molten material is obtained by polymerizing 1,5-pentanediamine and adipic acid, the molten material is transported to a spinning beam by a molten booster pump, and either spun directly or using tip spinning is used to first prepare a low-viscosity polyamide 56 resin by polymerization of 1,5-pentanediamine and adipic acid, then a high-viscosity polyamide 56 resin is obtained by solid-phase tackification, and the high-viscosity polyamide 56 resin is heated to a molten state to form a polyamide 56 molten material for spinning; (2) stretching the molten polyamide 56 obtained in step (1) to form a spinning yarn; and (3) Processing the spun yarn to obtain polyamide 56 industrial yarn; Here, In step (1), the heat stabilizer is added during the polymerization of 1,5-pentanediamine and adipic acid, or injected online in the form of a heat stabilizer masterbatch before cutting the polymer melt into pellets, or blended in the form of a heat stabilizer masterbatch during spinning; The copper ion content in the heat stabilizer masterbatch is 0.5 to 10% by weight; The aforementioned heat stabilizer masterbatch is added in an amount of 0.3 to 5.0% by weight; The substrate for the heat stabilizer masterbatch comprises any one of polyamide 6, polyamide 56, polyamide 66, polyamide 510, polyamide 610, polybutylene terephthalate, or a combination thereof; and / or The method further includes the step of adding other additives, which include one of the following: a matting agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent, a fluorescent whitening agent, and an antistatic agent, or a combination thereof.

10. The method according to claim 9, characterized in that step (1) polymerization of 1,5-pentanediamine and adipic acid specifically includes the following steps: (1-1) Under inert gas or vacuum conditions, 1,5-pentanediamine, adipic acid, and water are homogeneously mixed to obtain a polyamide 56 salt solution; where the molar ratio of 1,5-pentanediamine to adipic acid is (0.95-1.2):1; (1-2) The polyamide 56 salt solution is heated to increase the pressure in the reaction system to 0.3 to 2.5 MPa, degassed, and maintain the pressure. Then, the pressure in the reaction system is reduced to 0 to 0.2 MPa, and the system is evacuated to a vacuum of -(0.01 to 0.1) MPa (gauge pressure) to obtain a molten polyamide 56.

11. In process (1), The low-viscosity polyamide 56 resin in 96% sulfuric acid has a relative viscosity of 2.0 to 2.7, and / or The heating in step (1) is carried out in a screw extruder, which includes five heating zones; The method according to claim 10, characterized in that the temperature of the first zone is 250 to 290°C, the temperature of the second zone is 260 to 300°C, the temperature of the third zone is 270 to 320°C, the temperature of the fourth zone is 280 to 330°C, and the temperature of the fifth zone is 280 to 320°C.

12. The method according to claim 9, characterized in that step (2) specifically includes the following steps: Forming a spun yarn by ejecting molten polyamide 56 through the spinneret plate of a spinning beam; and / or, The temperature of the spinning beam is 270 to 330°C, and / or The spinning pack pressure of the spinning beam is 8 to 25 MPa and / or The draw ratio of the spindle of the aforementioned spindle plate is 50 to 400.

13. The method according to claim 9, characterized in that step (3) specifically includes the following steps: Insulating, cooling, spinning, stretching, and winding the spun yarn coming out of the spinneret orifice to obtain polyamide 56 industrial yarn; and / or The aforementioned insulation is carried out by a slow cooling device, where the slow cooling temperature is 150 to 280°C; the slow cooling length is 10 to 80 mm; the cooling is carried out with rapid cooling air, where the air velocity of the rapid cooling air is 0.3 to 2.0 m / s; the air temperature of the rapid cooling air is 15 to 25°C; and / or the humidity of the rapid cooling air is 60 to 80%; and / or, The winding tension when winding the aforementioned spun yarn into shape is 50 to 300 cN; or The winding speed is 2,000 to 3,800 m / min; and / or the winding overfeed ratio is 5% or less.

14. The stretching is carried out in four or more stages. The stretching process includes, firstly, supplying the spun yarn to a first pair of hot rollers via a godet roller and performing a first stage of stretching between the first pair of hot rollers and a second pair of hot rollers; performing a second stage of stretching between the second pair of hot rollers and a third pair of hot rollers; performing a third stage of stretching and a first stage of heat setting between the third pair of hot rollers and a fourth pair of hot rollers; and performing a fourth stage of stretching and a second stage of heat setting between the fourth pair of hot rollers and a fifth pair of hot rollers; The temperature of the first heat set is 180-250°C; and / or The method according to claim 13, characterized in that the temperature of the second heat set is 200 to 240°C.

15. The method according to claim 9, characterized in that the de-oiled yarn of the polyamide 56 industrial yarn has a relative viscosity of 2.7 to 4.5, and the absolute value of the difference between the relative viscosity of the de-oiled yarn and the relative viscosity of the raw material resin is 0.12 or less.

16. The method according to claim 15, characterized in that the absolute value of the difference between the relative viscosity of the de-oiled yarn and the relative viscosity of the raw material resin is 0.10 or less.

17. The method according to claim 9, characterized in that the de-oiled polyamide 56 industrial yarn has an amino acid content of 20 to 50 mmol / kg, and the absolute difference between the amino acid content of the de-oiled yarn and the amino acid content of the raw material resin is 5 or less.

18. The method according to claim 17, characterized in that the absolute difference between the amino content of the de-oiled yarn and the amino content of the raw material resin is 3 or less.

19. The method according to claim 9, characterized in that the filaments of the polyamide 56 industrial yarn break no more than twice every 24 hours, and the manufacturing yield of the polyamide 56 industrial yarn is 90% or more.

20. Use of polyamide 56 industrial yarn according to any one of claims 1 to 8 in the fields of sewing thread, tire cord, airbag thread, release cloth, water cloth, canvas, safety belt, rope, fishing net, industrial filter cloth, conveyor belt, parachute, tent, bag and suitcase.