POLYAMIDE 5X INDUSTRIAL YARN, PREPARATION METHOD THEREFOR AND USE THEREOF

Abstract

Disclosed in the present invention is a polyamide 5X industrial yarn. The polyamide 5X industrial yarn has a heat-resistant break strength retention rate of 90% or more after being treated at 180° C. for 4 hrs; a heat-resistant break strength retention rate of 90% or more after being treated at 230° C. for 30 mins; and a dry heat shrinkage of 8.0% or less. The polyamide 5X industrial yarn is widely used in the fields of sewing threads, tire cords, air bag yarns, release cloth, krama, canvas, safety belts, ropes, fishing nets, industrial filter cloth, conveyor belts, parachutes, tents, bags and suitcases.

Claims

1-25. (canceled)

26. A polyamide 5X industrial yarn, wherein the content of copper ions in the polyamide 5X industrial yarn is 10-1,000 ppm, and the polyamide 5X comprises any one of polyamide 56, polyamide 510, polyamide 512, polyamide 513 or polyamide 514.

27. The polyamide 5X industrial yarn according to claim 26, wherein the content of copper ions in the polyamide 5X industrial yarn is 30-500 ppm, or 50-200 ppm.

28. The polyamide 5X industrial yarn according to claim 26, wherein: (i) the polyamide 5X industrial yarn has: (a) a heat-resistant break strength retention rate of 90% or more after being treated at 180° C. for 4 hrs; and/or a (b) heat-resistant break strength retention rate of 90% or more after being treated at 230° C. for 30 mins; and/or (c) the polyamide 5X industrial yarn has a dry heat shrinkage of 8.0% or less; or (ii) the polyamide 5X industrial yarn has: (a) a heat-resistant break strength retention rate of 93% or more after being treated at 180° C. for 4 hrs; and/or (b) a heat-resistant break strength retention rate of 92% or more after being treated at 230° C. for 30 mins; and/or (c) the polyamide 5X industrial yarn has a dry heat shrinkage of 6.0% or less.

29. A polyamide 5X industrial yarn, wherein: the polyamide 5X industrial yarn comprises a heat stabilizer, further wherein the heat stabilizer comprises any 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 10-2,800 ppm, or 100-2,500 ppm, based on the total weight of production raw materials.

30. The polyamide 5X industrial yarn according to claim 29, wherein: the heat stabilizer comprises a composition of potassium iodide and copper acetate, and the molar ratio of copper acetate to potassium iodide is 1:1-15.

31. The polyamide 5X industrial yarn according to claim 26, wherein the polyamide 5X industrial yarn has a break strength of: 6.5 cN/dtex or more, or 7.0 cN/dtex or more, or 8.0 cN/dtex or more.

32. The polyamide 5X industrial yarn according to claim 26, wherein: the oil-free yarn of the polyamide 5X industrial yarn has a relative viscosity of 2.7-4.5, and the absolute value of the difference between the relative viscosity of the oil-free yarn and the relative viscosity of its original resin is 0.12 or less.

33. The polyamide 5X industrial yarn according to claim 32, wherein the absolute value of the difference between the relative viscosity of the oil-free yarn of the polyamide 5X industrial yarn and the relative viscosity of its original resin is: 0.10 or less, or 0.08 or less.

34. The polyamide 5X industrial yarn according to claim 26, wherein: the oil-free yarn of the polyamide 5X industrial yarn has an amino content of 20-50 mmol/kg; and the absolute value of the difference between the amino content of the oil-free yarn and the amino content of its original resin is 5 or less.

35. The polyamide 5X industrial yarn according to claim 34, wherein the absolute value of the difference between the amino content of the oil-free yarn and the amino content of its original resin is: 3 or less, or 2 or less.

36. The polyamide 5X industrial yarn according to claim 26, wherein the filament of the polyamide 5X industrial yarn breaks: 2 times or less every 24 hrs, or 1 time or less every 24 hrs, or 0 time every 24 hrs; and the production yield of the polyamide 5X industrial yam is 90% or more, or 93% or more, or 96% or more.

37. The polyamide 5X industrial yarn according to claim 26, wherein the polyamide 5X industrial yarn has a shrinkage in boiling water of: 8.0% or less, or 7.0% or less, or 6.0% or less; and/or the polyamide 5X industrial yarn has a fineness of: 100-3,500 dtex, or 200-2,500 dtex, or 300-1,800 dtex; and/or the polyamide 5X industrial yarn has an elongation at break of 26% or less, or 22% or less; and/or the polyamide 5X industrial yarn has a crystallinity of 70% or more, or 72% or more, or 74% or more; and/or the polyamide 5X industrial yarn has an orientation degree of 80% or more, or 82% or more, or 84% or more.

38. The polyamide 5X industrial yam according to claim 26, wherein the raw materials for producing the polyamide 5X industrial yarn at least comprise: 1,5-pentane diamine and adipic acid; or a polyamide 5X obtained by polymerizing 1,5-pentane diamine and adipic acid as monomers; optionally wherein the 1,5-pentane diamine is prepared from bio-based raw materials by a fermentation process or an enzymatic conversion process.

39. A process for producing a polyamide 5X industrial yarn according to claim 26, wherein the process comprises the following steps: (1) polymerizing 1,5-pentane diamine and adipic acid to obtain a high-viscosity polyamide 5X melt, conveying the melt to a spinning beam by a melt booster pump, and spinning directly; or by use of chip spinning by initially preparing a low-viscosity polyamide 5X resin, and then obtaining a high-viscosity polyamide 5X resin by solid phase tackifying, and then heating the high-viscosity polyamide 5X resin into a molten state so as to form a polyamide 5X melt suitable for spinning; (2) drawing the polyamide 5X melt obtained in Step (1) to form an as-spun yarn; and (3) processing the as-spun yam formed in Step (2) to obtain the polyamide 5X industrial yam; wherein: a heat stabilizer is: added during the polymerization of 1,5-pentane diamine and adipic acid in Step (1), 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 the spinning; the content of copper ions in the heat stabilizer masterbatch is 0.5-10 wt %, or 0.8-5 wt %, or 1.2-3 wt %; the heat stabilizer masterbatch is added in an amount of 0.3-5.0 wt %, or 0.5-3.0 wt %, or 0.8-2.0 wt %; and wherein the base material 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, or any of polyamide 6, polyamide 56 and/or polyamide 510, or polyamide 6 and/or polyamide 56; and/or wherein optionally, the process further comprises the step of adding other additive(s) comprising any one of matting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, fluorescent brighteners and anti-static agents, or combination thereof; and the other additive(s) are added in an amount of 0.01-5 wt %, based on the total weight of the production raw materials.

40. The process according to claim 39, wherein Step (1) comprises the following steps: (1-1) mixing 1,5-pentane diamine, adipic acid and water uniformly under an inert gas or vacuum condition to obtain a polyamide 5X salt solution; wherein the molar ratio of 1,5-pentane diamine to adipic acid is (0.95-1.2): 1; (1-2) heating the polyamide 5X salt solution, increasing the pressure in the reaction system to 0.3-2.5 MPa, degassing, maintaining the pressure, then reducing the pressure in the reaction system to 0-0.2 MPa, and evacuating to a vacuum degree of −(0.01-0.1) MPa (gauge pressure) to obtain a polyamide 5X melt; wherein optionally: the temperature of the reaction system at the end of the pressure-maintenance is 230-275° C.; and/or the temperature of the reaction system at the end of the pressure-reduction is completed is 240-285° C.; and/or the temperature at the end of evacuation is 265-295° C.

41. The process according to claim 39, wherein in Step (1), the low-viscosity polyamide 5X resin in 96% sulfuric acid has a relative viscosity of: 2.0-2.7, or 2.2-2.6, or 2.4-2.5; and/or the high-viscosity polyamide 5X resin in 96% sulfuric acid has a relative viscosity of: 2.7-4.5, or 3.2-4.0, or 3.4-3.6; and/or the high-viscosity polyamide 5X resin has an oligomer content of: 0.2-1.0 wt %, or 0.4-0.6 wt %; and/or the high-viscosity polyamide 5X resin has a number average molecular weight of: 18,000-40,000, or 25,000-30,000, and/or the high-viscosity polyamide 5X resin has a molecular weight distribution of 0.8-1.8, or 1.2-1.5; and/or the high-viscosity polyamide 5X resin has a moisture content of: 200-800 ppm, or 300-750 ppm, or 350-700 ppm, or 400-600 ppm; and/or the high-viscosity polyamide 5X resin has an amino content of: 20-50 mmol/kg, or 24-45 mmol/kg, or 28-40 mmol/kg, or 32-36 mmol/kg; and/or wherein optionally, the heating in Step (1) is carried out in a screw extruder, and further optionally the screw extruder includes five heating zones; and the temperature of a first zone is 250-290° C., the temperature of a second zone is 260-300° C., the temperature of a third zone is 270-320° C., the temperature of a fourth zone is 280-330° C., and the temperature of a fifth zone is 280-320° C.

42. The process according to claim 39, wherein Step (2) comprises the following steps: ejecting the polyamide 5X melt through the spinneret plate of the spinning beam to form the as-spun yarn; wherein optionally: the temperature of the spinning beam is: 270-330° C., or 280-310° C., or 290-300° C., or 293-297° C.; and/or the pressure of the spin pack of the spinning beam is: 8-25 MPa, or 12-20 MPa, or 15-18 MPa; and/or the drawing ratio of the spinneret of the spinneret plate is: 50-400, or 70-300, or 80-200, or 90-100.

43. The process according to claim 39, wherein Step (3) comprises the following steps: thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yam into a shape which comes out of the spinneret orifices to obtain the polyamide 5X industrial yarn; wherein optionally, the thermal insulation is performed with a slow cooling device, wherein the slow cooling temperature is: 150-280° C., or 200-240° C., and the slow cooling length is 10-80 mm, or 20-50 mm; the cooling is performed with quench air, wherein the air speed of the quench air is 0.3-2.0 m/s, or 0.6-1.5 m/s; the air temperature of the quench air is 15-25° C., or 17-23° C., or 19-22° C.; and/or the humidity of the quench air is 60-80%, or 65-75%; and/or the winding tension during winding the as-spun yam into a shape is 50-300 cN, or 80-200 cN, or 100-160 cN, or 120-140 cN; or the winding speed is 2,000-3,800 m/min, or 2,500-3,500 m/min, or 2,800-3,000 m/min; and/or the winding overfeed ratio is 5% or less, or 4% or less, or 3% or less.

44. The process according to claim 39, wherein the drawing is performed in four or more stages; wherein optionally, the drawing process comprises: initially feeding the as-spun yarn, which has been spin finished, to a first pair of hot rollers through a godet roller, and performing a first-stage drawing between the first pair of hot rollers and a second pair of hot rollers; preforming a second-stage drawing between the second pair of hot rollers and a third pair of hot rollers; performing a third-stage drawing and a first thermal setting between the third pair of hot rollers and a fourth pair of hot rollers; and then performing a fourth-stage drawing and a second thermal setting between the fourth pair of hot rollers and a fifth pair of hot rollers; further optionally wherein: the total drawing ratio is 4.0-6.0; the temperature of the first thermal setting is 180-250° C., or 200-240° C.; and/or the temperature of the second thermal setting is 200-240° C., or 220-230° C.

45. A method of using the polyamide 5X industrial yarn according to claim 26 in a manufacturing process which produces any one of the following: sewing threads, tire cords, air bag yarns, release cloth, krama, canvas, safety belts, ropes, fishing nets, industrial filter cloth, conveyor belts, parachutes, tents, bags and suitcases.

Description

EXAMPLE 1

Polyamide 56 Industrial Yarn (933dtex/140f)

[0095] The process comprised the following steps:

[0096] 1. Polymerization:

[0097] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition, and adding copper acetate as a heat stabilizer in an amount of 200 ppm based on the total weight of the raw materials to obtain a polyamide 56 salt solution with a concentration of 60%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was1.05:1;

[0098] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.2 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 265° C., reducing the pressure in the reaction system to 0.1 MPa with the temperature of the reaction system at the end of the pressure reduction being 275° C., and evacuating to a vacuum degree of −0.05 MPa with the temperature at the end of evacuation being 285° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0099] (3) solid phase tackifying the low-viscosity polyamide 56 resin to prepare a high-viscosity polyamide 56 resin; wherein the temperature of the solid phase tackifying was 155° C., and the drying time was 20 hours; the low-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.4; the high-viscosity polyamide 56 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 moisture content of 400 ppm, and an amino content of 36.5 mmol/kg.

[0100] 2. Spinning:

[0101] (1) heating the high-viscosity polyamide 56 resin into a molten state so as to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder included five heating zones, wherein the temperature of a first zone was 255° C., the temperature of a second zone was 270° C., the temperature of a third zone was 280° C., the temperature of a fourth zone was 290° C., and the temperature of a fifth zone was 300° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 290° C., the pressure of the pack was 15 MPa, and the drawing ratio of the spinneret was 150;

[0102] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn;

[0103] the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 220° C., and the slow cooling length was 20 mm;

[0104] the cooling was performed with quench air, and the air speed was 1.2 m/s; the air temperature was 22° C.; and the humidity was 70%.

[0105] The drawing was performed in four stages comprising: firstly, feeding the as-spun yarn, which had been spin finished, to a first pair of hot rollers through a godet roller; performing a first-stage drawing between the first pair of hot rollers and a second pair of hot rollers; preforming a second-stage drawing between the second pair of hot rollers and a third pair of hot rollers; performing a third-stage drawing and a first thermal setting between the third pair of hot rollers and a fourth pair of hot rollers; and then performing a fourth-stage drawing and a second thermal setting between the fourth pair of hot rollers and a fifth pair of hot rollers; wherein the total drawing ratio was 5.0; the temperature of the first thermal setting was 220° C.; and the temperature of the second thermal setting was 230° C. The winding tension during winding the as-spun yarn into a shape was 90 cN; the winding speed was 3,500 m/min; and the winding overfeed ratio was 2%.

EXAMPLE 2

Polyamide 56 Industrial Yarn (830 dtex/192f)

[0106] The process comprised the following steps:

[0107] 1. Polymerization:

[0108] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition, and adding copper acetate as a heat stabilizer in an amount of 500 ppm based on the total weight of the raw materials to obtain a polyamide 56 salt solution with a concentration of 60%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.1:1;

[0109] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.3 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 255° C., reducing the pressure in the reaction system to 0 MPa with the temperature of the reaction system at the end of the pressure reduction being 265° C., and evacuating to a vacuum degree of −0.08 MPa with the temperature at the end of evacuation being 275° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0110] (3) solid phase tackifying the low-viscosity polyamide 56 resin to prepare a high-viscosity polyamide 56 resin; wherein the temperature for the solid phase tackifying was 160° C., and the drying time was 18 hours; the low-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.5; the high-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 3.5, an oligomer content of 0.6 wt %, a number average molecular weight of 33,000, a molecular weight distribution of 1.5, a moisture content of 450 ppm, and an amino content of 33.5 mmol/kg.

[0111] 2. Spinning:

[0112] (1) heating the high-viscosity polyamide 56 resin into a molten state so as to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder included in particular five heating zones, wherein the temperature of a first zone was 265° C., the temperature of a second zone was 275° C., the temperature of a third zone was 285° C., the temperature of a fourth zone was 295° C., and the temperature of a fifth zone was 305° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 295° C., the pressure of the pack was 18 MPa and the drawing ratio of the spinneret was 180;

[0113] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 230° C., and the slow cooling length was 30 mm; the cooling was performed with quench air, and the air speed was 0.8 m/s; the air temperature was 23° C.; and the humidity was 75%; the winding tension during winding the as-spun yarn into a shape was 80 cN; the winding speed was 3,000 m/min; and the winding overfeed ratio was 3%. The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 4.8; the temperature of the first thermal setting was 225° C.; and the temperature of the second thermal setting was 240° C.

EXAMPLE 3

Polyamide 56 Industrial Yarn (550 dtex/96f)

[0114] The process comprised the following steps:

[0115] 1. Polymerization:

[0116] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition, and adding cuprous iodide as a heat stabilizer in an amount of 150 ppm based on the total weight of the raw materials to obtain a polyamide 56 salt solution with a concentration of 65%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.1:1;

[0117] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.3 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 240° C., reducing the pressure in the reaction system to 0.1 MPa with the temperature of the reaction system at the end of the pressure reduction being 270° C., and evacuating to a vacuum degree of −0.05 MPa with the temperature at the end of evacuation being 280° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0118] (3) solid phase tackifying the low-viscosity polyamide 56 resin to prepare a high-viscosity polyamide 56 resin; wherein the temperature of the solid phase tackifying was 160° C., and the drying time was 22 hours;

[0119] the low-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.6; the high-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 3.0, an oligomer content of 0.8 wt %, a number average molecular weight of 30,000, a molecular weight distribution of 1.6, a moisture content of 400 ppm, and an amino content of 42.5 mmol/kg.

[0120] 2. Spinning:

[0121] (1) heating the high-viscosity polyamide 56 resin into a molten state so as to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder was in particular divided into five heating zones, wherein the temperature of a first zone was 248° C., the temperature of a second zone was 263° C., the temperature of a third zone was 276° C., the temperature of a fourth zone was 285° C., and the temperature of a fifth zone was 293° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form the as-spun yarn; wherein the temperature of the spinning beam was 285° C., the pressure of the pack was 16 MPa and the drawing ratio of the spinneret was 100;

[0122] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 220° C., and the slow cooling length was 25 mm; the cooling was performed with quench air, and the air speed was 1.4 m/s; the air temperature was 22° C.; and the humidity was 65%; the winding tension during winding the as-spun yarn into a shape was 55 cN; the winding speed was 2,800 m/min; and the winding overfeed ratio was 2.5%. The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 5.0; the temperature of the first thermal setting was 220° C.; and the temperature of the second thermal setting was 235° C.

EXAMPLE 4

Polyamide 56 Industrial Yarn (550 dtex/96f)

[0123] The process comprised the following steps:

[0124] 1. Polymerization:

[0125] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition, and adding cuprous iodide as a heat stabilizer in an amount of 250 ppm based on the total weight of the raw materials to obtain a polyamide 56 salt solution with a concentration of 65%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.12:1;

[0126] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.4 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 245° C., reducing the pressure in the reaction system to 0.1 MPa with the temperature of the reaction system at the end of the pressure reduction being 275° C., and evacuating to a vacuum degree of −0.07 MPa with the temperature at the end of evacuation being 280° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0127] (3) solid phase tackifying the low-viscosity polyamide 56 resin to prepare a high-viscosity polyamide 56 resin; wherein the temperature of the solid phase tackifying was 150° C., and the drying time was 25 hours; the low-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.55; the high-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.9, an oligomer content of 0.8 wt %, a number average molecular weight of 28,000, a molecular weight distribution of 1.5, a moisture content of 300 ppm, and an amino content of 40.5 mmol/kg.

[0128] 2. Spinning:

[0129] (1) heating the high-viscosity polyamide 56 resin into a molten state so as to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder was in particular divided into five heating zones, wherein the temperature of a first zone was 245° C., the temperature of a second zone was 260° C., the temperature of a third zone was 270° C., the temperature of a fourth zone was 285° C., and the temperature of a fifth zone was 290° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 280° C., the pressure of the pack was 10 MPa and the drawing ratio of the spinneret was 200;

[0130] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 210° C., and the slow cooling length was 25mm; the cooling was performed with quench air, and the air speed was 1.3 m/s; the air temperature was 24° C.; and the humidity was 65%; the winding tension during winding the as-spun yarn into a shape was 55 cN; the winding speed was 2,600 m/min; and the winding overfeed ratio was 2.5%. The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 5.3; the temperature of the first thermal setting was 225° C.; and the temperature of the second thermal setting was 235° C.

EXAMPLE 5

Polyamide 56 Industrial Yarn (233 dtex/36f)

[0131] The process comprised the following steps:

[0132] 1. Polymerization:

[0133] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition, and adding cuprous iodide as a heat stabilizer in an amount of 400 ppm based on the total weight of the raw materials to obtain a polyamide 56 salt solution with a concentration of 65%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.05:1;

[0134] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.0 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 260° C., reducing the pressure in the reaction system to 0.1 MPa with the temperature of the reaction system at the end of the pressure reduction being 275° C., and evacuating to a vacuum degree of −0.08 MPa with the temperature at the end of evacuation being 295° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0135] (3) solid phase tackifying the low-viscosity polyamide 56 resin to prepare a high-viscosity polyamide 56 resin; wherein the temperature of the solid phase tackifying was 155° C., and the drying time was 25 hours;

[0136] the low-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.45; the high-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 3.6, an oligomer content of 1.0 wt %, a number average molecular weight of 36,000, a molecular weight distribution of 1.7, a moisture content of 350 ppm, and an amino content of 46.5 mmol/kg.

[0137] 2. Spinning:

[0138] (1) heating the high-viscosity polyamide 56 resin into a molten state so as to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder was in particular divided into five heating zones, wherein the temperature of a first zone was 255° C., the temperature of a second zone was 275° C., the temperature of a third zone was 280° C., the temperature of a fourth zone was 295° C., and the temperature of a fifth zone was 310° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 295° C., the pressure of the pack was 19 MPa and the drawing ratio of the spinneret was 250;

[0139] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 220° C., and the slow cooling length was 20 mm; the cooling was performed with quench air, and the air speed was 1.0 m/s; the air temperature was 18° C.; and the humidity was 70%; the winding tension during winding the as-spun yarn into a shape was 23 cN; the winding speed was 2,900 m/min; and the winding overfeed ratio was 1.5%. The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 5.5; the temperature of the first thermal setting was 230° C.; and the temperature of the second thermal setting was 230° C.

EXAMPLE 6

Polyamide 56 Industrial Yarn (1,670 dtex/192f)

[0140] The process comprised the following steps:

[0141] 1. Polymerization:

[0142] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition, and adding a heat stabilizer to obtain a polyamide 56 salt solution with a concentration of 65%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.1:1; the heat stabilizer was a composite of copper acetate and potassium iodide, wherein copper acetate was added in an amount of 200 ppm based on the total weight of the production raw materials, and potassium iodide was added in an amount of 500 ppm based on the total weight of the production raw materials.

[0143] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.3 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 255° C., reducing the pressure in the reaction system to 0.1 MPa with the temperature of the reaction system at the end of the pressure reduction being 270° C., and evacuating to a vacuum degree of −0.01 MPa with the temperature at the end of evacuation being 280° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0144] (3) solid phase tackifying the low-viscosity polyamide 56 resin to prepare a high-viscosity polyamide 56 resin; wherein the temperature of the solid phase tackifying was 155° C., and the drying time was 30 hours;

[0145] the low-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.7; the high-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 3.8, an oligomer content of 0.8 wt %, a number average molecular weight of 38,000, a molecular weight distribution of 1.5, a moisture content of 500 ppm, and an amino content of 42.5 mmol/kg.

[0146] 2. Spinning:

[0147] (1) heating the high-viscosity polyamide 56 resin into a molten state so as to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder was in particular divided into five heating zones, wherein the temperature of a first zone was 250° C., the temperature of a second zone was 275° C., the temperature of a third zone was 280° C., the temperature of a fourth zone was 295° C., and the temperature of a fifth zone was 305° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 290° C., the pressure of the pack was 14 MPa and the drawing ratio of the spinneret was 120;

[0148] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 230° C., and the slow cooling length was 40 mm; the cooling was performed with quench air, and the air speed was 1.1 m/s; the air temperature was 23° C.; and the humidity was 75%; the winding tension during winding the as-spun yarn into a shape was 160 cN;

[0149] the winding speed was 3,200 m/min; and the winding overfeed ratio was 3.5%. The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 5.6; the temperature of the first thermal setting was 225° C.; and the temperature of the second thermal setting was 235° C.

EXAMPLE 7

Polyamide 56 Industrial Yarn (2,800 dtex/480f)

[0150] The process comprised the following steps:

[0151] 1. Polymerization:

[0152] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition, and adding a heat stabilizer to obtain a polyamide 56 salt solution with a concentration of 65%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.05:1; the heat stabilizer was a composite of copper acetate and potassium iodide, wherein copper acetate was added in an amount of 250 ppm based on the total weight of the production raw materials, and potassium iodide was added in an amount of 2,000 ppm based on the total weight of the production raw materials.

[0153] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.2 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 260° C., reducing the pressure in the reaction system to 0.1 MPa with the temperature of the reaction system at the end of the pressure reduction being 285° C., and evacuating to a vacuum degree of −0.03 MPa with the temperature at the end of evacuation being 290° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0154] (3) solid phase tackifying the low-viscosity polyamide 56 resin to prepare a high-viscosity polyamide 56 resin; wherein the temperature of the solid phase tackifying was 155° C., and the drying time was 30 hours;

[0155] the low-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.35; the high-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 3.2, an oligomer content of 0.8 wt %, a number average molecular weight of 32,000, a molecular weight distribution of 1.5, a moisture content of 450 ppm, and an amino content of 38.5 mmol/kg.

[0156] 2. Spinning:

[0157] (1) heating the high-viscosity polyamide 56 resin into a molten state so as to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder was in particular divided into five heating zones, wherein the temperature of a first zone was 258° C., the temperature of a second zone was 276° C., the temperature of a third zone was 288° C., the temperature of a fourth zone was 298° C., and the temperature of a fifth zone was 305° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 293° C., the pressure of the pack was 12 MPa and the drawing ratio of the spinneret was 160;

[0158] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 230° C., and the slow cooling length was 20 mm; the cooling was performed with quench air, and the air speed was 1.2 m/s; the air temperature was 23° C.; and the humidity was 70%; the winding tension during winding the as-spun yarn into a shape was 280 cN; the winding speed was 2,700 m/min; and the winding overfeed ratio was 3%.

[0159] The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 4.8; the temperature of the first thermal setting was 220° C.; and the temperature of the second thermal setting was 230° C.

EXAMPLE 8

Polyamide 56 Industrial Yarn (233 dtex/36f)

[0160] The process comprised the following steps:

[0161] 1. Polymerization:

[0162] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition, and adding a heat stabilizer to obtain a polyamide 56 salt solution with a concentration of 65%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.05:1; the heat stabilizer was a composite of copper acetate and potassium iodide, wherein copper acetate was added in an amount of 150 ppm based on the total weight of the production raw materials, and potassium iodide was added in an amount of 800 ppm based on the total weight of the production raw materials.

[0163] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.2 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 260° C., reducing the pressure in the reaction system to 0.1 MPa with the temperature of the reaction system at the end of the pressure reduction being 285° C., and evacuating to a vacuum degree of −0.01 MPa with the temperature at the end of evacuation being 290° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0164] (3) solid phase tackifying the low-viscosity polyamide 56 resin to prepare a high-viscosity polyamide 56 resin; wherein the temperature of the solid phase tackifying was 155° C., and the drying time was 30 hours;

[0165] the low-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.4; 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 33,000, a molecular weight distribution of 1.6, a moisture content of 550 ppm, and an amino content of 33.5 mmol/kg.

[0166] 2. Spinning:

[0167] (1) heating the high-viscosity polyamide 56 resin into a molten state so as to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder was in particular divided into five heating zones, wherein the temperature of a first zone was 268° C., the temperature of a second zone was 280° C., the temperature of a third zone was 290° C., the temperature of a fourth zone was 295° C., and the temperature of a fifth zone was 303° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 298° C., the pressure of the pack was 18 MPa and the drawing ratio of the spinneret was 120;

[0168] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 220° C., and the slow cooling length was 30 mm; the cooling was performed with quench air, and the air speed was 1.2 m/s; the air temperature was 23° C.; and the humidity was 70%; the winding tension during winding the as-spun yarn into a shape was 140 cN; the winding speed was 3,000 m/min; and the winding overfeed ratio was 2%.

[0169] The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 4.8; the temperature of the first thermal setting was 220° C.; and the temperature of the second thermal setting was 230° C.

EXAMPLE 9

Polyamide 56 Industrial Yarn (933 dtex/140f)

[0170] The process comprised the following steps:

[0171] 1. Polymerization:

[0172] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition, and adding copper chloride as a heat stabilizer in an amount of 300 ppm based on the total weight of the raw materials to obtain a polyamide 56 salt solution with a concentration of 65%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.1:1;

[0173] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.25 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 260° C., reducing the pressure in the reaction system to 0.1 MPa with the temperature of the reaction system at the end of the pressure reduction being 275° C., and evacuating to a vacuum degree of −0.01 MPa with the temperature at the end of evacuation being 280° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0174] (3) solid phase tackifying the low-viscosity polyamide 56 resin to prepare a high-viscosity polyamide 56 resin; wherein the temperature of the solid phase tackifying was 160° C., and the drying time was 22 hours;

[0175] the low-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.4; 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 33,000, a molecular weight distribution of 1.6, a moisture content of 550 ppm, and an amino content of 33.5 mmol/kg.

[0176] 2. Spinning:

[0177] (1) heating the high-viscosity polyamide 56 resin into a molten state so as to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder was in particular divided into five heating zones, wherein the temperature of a first zone was 268° C., the temperature of a second zone was 280° C., the temperature of a third zone was 290° C., the temperature of a fourth zone was 295° C., and the temperature of a fifth zone was 303° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 280° C., the pressure of the pack was 13 MPa and the drawing ratio of the spinneret was 150;

[0178] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 200° C., and the slow cooling length was 40 mm; the cooling was performed with quench air, and the air speed was 1.3 m/s; the air temperature was 20° C.; and the humidity was 70%; the winding tension during winding the as-spun yarn into a shape was 90 cN; the winding speed was 2,700 m/min; and the winding overfeed ratio was 2.5%.

[0179] The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 4.8; the temperature of the first thermal setting was 210° C.; and the temperature of the second thermal setting was 220° C.

EXAMPLE 10

Polyamide 56 Industrial Yarn (933 dtex/140f)

[0180] The process comprised the following steps:

[0181] 1. Polymerization:

[0182] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition to obtain a polyamide 56 salt solution with a concentration of 65%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.15:1;

[0183] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.3 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 265° C., reducing the pressure in the reaction system to 0 MPa with the temperature of the reaction system at the end of the pressure reduction being 275° C., and evacuating to a vacuum degree of −0.04 MPa with the temperature at the end of evacuation being 285° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0184] 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 %, and the addition amount of the heat stabilizer masterbatch was 1.5 wt %; the heat stabilizer masterbatch base material was polyamide 56; the process for producing the heat stabilizer masterbatch comprised the following steps: (a) drying the base material polyamide 56 in vacuum, and then grinding it into powders; the polyamide 56 was 65 parts by weight, the relative viscosity thereof was 2.9, the number average molecular weight thereof was 24 kg/mol, the molecular weight distribution thereof was 2.1, and the moisture content thereof was 500 ppm; (b) mixing the powders obtained in Step (a) with 12.5 parts by weight of heat stabilizer cuprous iodide, 0.5 parts by weight of lubricant Wax OP, 0.2 parts by weight of Antioxidant 168, melting, extruding and pelletizing the mixture with a twin-screw to obtain a heat stabilizer masterbatch, wherein the processing temperature of each zone was set as follows: the temperature of a first zone was 251° C., the temperature of a second zone was 264° C., the temperature of a third zone was 269° C., the temperature of a fourth zone was 273° C., and the temperature of a fifth zone was 276° C.; the screw rotation speed was 250 r/min, and the filter screen was 150 mesh.

[0185] (3) solid phase tackifying the low-viscosity polyamide 56 resin to prepare a high-viscosity polyamide 56 resin; wherein the temperature of the solid phase tackifying was 155° C., and the drying time was 25 hours;

[0186] the low-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.5; the high-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 3.7, an oligomer content of 0.6 wt %, a number average molecular weight of 34,000, a molecular weight distribution of 1.5, a moisture content of 300 ppm, and an amino content of 33.8 mmol/kg.

[0187] 2. Spinning:

[0188] (1) heating the high-viscosity polyamide 56 resin into a molten state so as to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder was in particular divided into five heating zones, wherein the temperature of a first zone was 265° C., the temperature of a second zone was 278° C., the temperature of a third zone was 288° C., the temperature of a fourth zone was 295° C., and the temperature of a fifth zone was 300° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 295° C., the pressure of the pack was 14 MPa and the drawing ratio of the spinneret was 80;

[0189] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 230° C., and the slow cooling length was 25 mm; the cooling was performed with quench air, and the air speed was 1.1 m/s; the air temperature was 22° C.; and the humidity was 70%;

[0190] the winding tension during winding the as-spun yarn into a shape was 90 cN; the winding speed was 2,600 m/min; and the winding overfeed ratio was 2%.

[0191] the drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 5.0; the temperature of the first thermal setting was 220° C.; and the temperature of the second thermal setting was 230° C.

EXAMPLE 11

Polyamide 56 Industrial Yarn (933 dtex/140f)

[0192] The process comprised the following steps:

[0193] 1. Polymerization:

[0194] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition to obtain a polyamide 56 salt solution with a concentration of 65%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.06:1;

[0195] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.2 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 265° C., reducing the pressure in the reaction system to 0.1 MPa with the temperature of the reaction system at the end of the pressure reduction being 275° C., and evacuating to a vacuum degree of −0.06 MPa with the temperature at the end of evacuation being 285° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0196] (3) solid phase tackifying the low-viscosity polyamide 56 resin to prepare a high-viscosity polyamide 56 resin; wherein the temperature of the solid phase tackifying was 160° C., and the drying time was 28 hours; the low-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.4; the high-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 3.3, an oligomer content of 0.9 wt %, a number average molecular weight of 32,000, a molecular weight distribution of 1.6, a moisture content of 450 ppm, and an amino content of 36.5 mmol/kg.

[0197] 2. Spinning:

[0198] (1) heating the high-viscosity polyamide 56 resin into a molten state so as to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder was in particular divided into five heating zones, wherein the temperature of a first zone was 255° C., the temperature of a second zone was 275° C., the temperature of a third zone was 280° C., the temperature of a fourth zone was 290° C., and the temperature of a fifth zone was 305° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 295° C., the pressure of the pack was 14 MPa and the drawing ratio of the spinneret was 140;

[0199] a heat stabilizer masterbatch was blended with a masterbatch addition device during the spinning, the content of copper ions in the heat stabilizer masterbatch was 1.8 wt %; the heat stabilizer masterbatch was added in an amount of 1.2 wt %; and the process for producing the heat stabilizer masterbatch was the same as that in Example 10.

[0200] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 240° C., and the slow cooling length was 20 mm; the cooling was performed with quench air, and the air speed was 1.4 m/s; the air temperature was 22° C.; and the humidity was 70%;

[0201] the winding tension during winding the as-spun yarn into a shape was 90 cN; the winding speed was 3,500 m/min; and the winding overfeed ratio was 2%.

[0202] The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 5.0; the temperature of the first thermal setting was 220° C.; and the temperature of the second thermal setting was 230° C.

EXAMPLE 12

Polyamide 56 Industrial Yarn (933 dtex/140f)

[0203] The process comprised the following steps:

[0204] 1. Polymerization:

[0205] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition to obtain a polyamide 56 salt solution with a concentration of 65%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.08:1;

[0206] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.2 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 265° C., reducing the pressure in the reaction system to 0 MPa with the temperature of the reaction system at the end of the pressure reduction being 275° C., and evacuating to a vacuum degree of −0.05 MPa with the temperature at the end of evacuation being 290° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0207] (3) solid phase tackifying the low-viscosity polyamide 56 resin to prepare a high-viscosity polyamide 56 resin; wherein the temperature of the solid phase tackifying was 160° C., and the drying time was 28 hours; the low-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 2.4; the high-viscosity polyamide 56 resin in 96% sulfuric acid had a relative viscosity of 3.2, an oligomer content of 0.8 wt %, a number average molecular weight of 30,000, a molecular weight distribution of 1.6, a moisture content of 400 ppm, and an amino content of 32.3 mmol/kg.

[0208] 2. Spinning:

[0209] (1) heating the high-viscosity polyamide 56 resin into a molten state so as to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder was in particular divided into five heating zones, wherein the temperature of a first zone was 250° C., the temperature of a second zone was 270° C., the temperature of a third zone was 285° C., the temperature of a fourth zone was 290° C., and the temperature of a fifth zone was 290° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 285° C., the pressure of the pack was 12 MPa and the drawing ratio of the spinneret was 180;

[0210] a heat stabilizer masterbatch was blended with a masterbatch addition device during the spinning, the content of copper ions in the heat stabilizer masterbatch was 1.6 wt %, and the heat stabilizer masterbatch was added in an amount of 1.5 wt %;

[0211] the heat stabilizer masterbatch base material was polyamide 6; the process for producing the heat stabilizer masterbatch comprised the following steps: (a) drying the base material polyamide 6 in vacuum, and then grinding it into powders; the polyamide 6 was 65 parts by weight, the relative viscosity thereof was 2.9, the number average molecular weight thereof was 24 kg/mol, the molecular weight distribution thereof was 2.1, and the moisture content thereof was 500 ppm; (b) mixing the powders obtained in Step (a) with 15 parts by weight of heat stabilizer cuprous iodide, 0.5 parts by weight of lubricant Wax OP, 0.2 parts by weight of Antioxidant 168, melting, extruding and pelletizing the mixture with a twin-screw to obtain a heat stabilizer masterbatch, wherein the processing temperature of each zone was set as follows: the temperature of a first zone was 200° C., the temperature of a second zone was 210° C., the temperature of a third zone was 220° C., the temperature of a fourth zone was 230° C., and the temperature of a fifth zone was 235° C., the screw rotation speed was 250 r/min, and the filter screen was 150 mesh.

[0212] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 225° C., and the slow cooling length was 20 mm; the cooling was performed with quench air, and the air speed was 1.2 m/s; the air temperature was 22° C.; and the humidity was 70%;

[0213] the winding tension during winding the as-spun yarn into a shape was 90 cN; the winding speed was 3,300 m/min; and the winding overfeed ratio was 2%.

[0214] The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 5.0; the temperature of the first thermal setting was 220° C.; and the temperature of the second thermal setting was 230° C.

EXAMPLE 13

Polyamide 56 Industrial Yarn (933 dtex/140f)

[0215] The process comprised the following steps:

[0216] 1. Polymerization:

[0217] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition, and adding cuprous iodide as a heat stabilizer in an amount of 200 ppm based on the total weight of the raw materials to obtain a polyamide 56 salt solution with a concentration of 65%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.1:1;

[0218] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.25 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 265° C., reducing the pressure in the reaction system to 0.1 MPa with the temperature of the reaction system at the end of the pressure reduction being 280° C., and evacuating to a vacuum degree of −0.01 MPa with the temperature at the end of evacuation being 295° C. to directly obtain a high-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures; the high-viscosity polyamide 56 melt 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 moisture content of 400 ppm, and an amino content of 32.5 mmol/kg.

[0219] 2. Spinning:

[0220] (1) conveying the high-viscosity polyamide 56 melt to a spinning beam by a melt booster pump, and spinning directly; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 280° C., the pressure of the pack was 18 MPa and the drawing ratio of the spinneret was 200;

[0221] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 220° C., and the slow cooling length was 20 mm; the cooling was performed with quench air, and the air speed was 1.2 m/s; the air temperature was 22° C.; and the humidity was 70%;

[0222] the winding tension during winding the as-spun yarn into a shape was 90 cN; the winding speed was 2,500 m/min; and the winding overfeed ratio was 2%.

[0223] The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 5.0; the temperature of the first thermal setting was 220° C.; and the temperature of the second thermal setting was 230° C.

EXAMPLE 14

Polyamide 56 Industrial Yarn (2,800 dtex/480f)

[0224] The process comprised the following steps:

[0225] 1. Polymerization:

[0226] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition, and adding a heat stabilizer to obtain a polyamide 56 salt solution with a concentration of 65%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.08:1; the heat stabilizer was a composite of copper acetate and potassium iodide, wherein copper acetate was added in an amount of 200 ppm based on the total weight of the production raw materials, and potassium iodide was added in an amount of 700 ppm based on the total weight of the production raw materials.

[0227] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.4 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 265° C., reducing the pressure in the reaction system to 0.1 MPa with the temperature of the reaction system at the end of the pressure reduction being 285° C., and evacuating to a vacuum degree of −0.06 MPa with the temperature at the end of evacuation being 290° C. to directly obtain a high-viscosity polyamide 56 melt; wherein all the pressures are gauge pressures; the high-viscosity polyamide 56 melt 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 moisture content of 450 ppm, and an amino content of 40.5 mmol/kg.

[0228] 2. Spinning:

[0229] (1) conveying the high-viscosity polyamide 56 melt to a spinning beam by a melt booster pump, and spinning directly; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 290° C., the pressure of the pack was 12 MPa and the drawing ratio of the spinneret was 180;

[0230] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 210° C., and the slow cooling length was 20 mm; the cooling was performed with quench air, and the air speed was 1.2 m/s; the air temperature was 23° C.; and the humidity was 70%;

[0231] the winding tension during winding the as-spun yarn into a shape was 280 cN; the winding speed was 2,900 m/min; and the winding overfeed ratio was 3%.

[0232] The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 4.5; the temperature of the first thermal setting was 220° C.; and the temperature of the second thermal setting was 230° C.

EXAMPLE 15

Polyamide 56 Industrial Yarn (1,670 dtex/192f)

[0233] The preparation process was the same as that in Example 6, except that the heat stabilizer was a composite of copper acetate and potassium iodide, wherein copper acetate was added in an amount of 200 ppm based on the total weight of the production raw materials, and potassium iodide was added in an amount of 1,000 ppm based on the total weight of the production raw materials.

EXAMPLE 16

Polyamide 56 Industrial Yarn (1,670 dtex/192f)

[0234] The preparation process was the same as that in Example 6, except that the heat stabilizer was a composite of copper acetate and potassium iodide, wherein copper acetate was added in an amount of 200 ppm based on the total weight of the production raw materials, and potassium iodide was added in an amount of 2,000 ppm based on the total weight of the production raw materials.

EXAMPLE 17

Polyamide 56 Industrial Yarn (1,670 dtex/192f)

[0235] The preparation process was the same as that in Example 6, except that the heat stabilizer was a composite of copper acetate and potassium iodide, wherein copper acetate was added in an amount of 200 ppm based on the total weight of the production raw materials, and potassium iodide was added in an amount of 1,800 ppm based on the total weight of the production raw materials.

EXAMPLE 18

Polyamide 56 Industrial Yarn (1,670 dtex/192f)

[0236] The preparation process was the same as that in Example 6, except that the heat stabilizer was a composite of copper acetate and potassium iodide, wherein copper acetate was added in an amount of 200 ppm based on the total weight of the production raw materials, and potassium iodide was added in an amount of 2,500 ppm based on the total weight of the production raw materials.

COMPARATIVE EXAMPLE 1

Polyamide 56 Industrial Yarn (933 dtex/140f)

[0237] The preparation method was the same as that in Example 1, except that heat stabilizer copper acetate was not added during the polymerization of 1,5-pentane diamine and adipic acid in Step (1).

COMPARATIVE EXAMPLE 2

Polyamide 56 Industrial Yarn (933 dtex/140f)

[0238] The preparation method was the same as that in Example 1, except that the obtained high-viscosity polyamide 56 resin has a moisture content of 1,200 ppm in the polymerization in Step 1.

COMPARATIVE EXAMPLE 3

Polyamide 56 Industrial Yarn (1,670 dtex/192f)

[0239] The process comprised the following steps:

[0240] 1. Polymerization:

[0241] (1) mixing raw materials 1,5-pentane diamine, adipic acid and water uniformly under a nitrogen condition, and adding a heat stabilizer to obtain a polyamide 56 salt solution with a concentration of 60%; wherein the molar ratio of 1,5-pentane diamine to adipic acid was 1.1:1; the heat stabilizer was a composite of copper acetate and potassium iodide, wherein copper acetate was added in an amount of 200 ppm based on the total weight of the production raw materials, and potassium iodide was added in an amount of 500 ppm based on the total weight of the production raw materials;

[0242] (2) heating the polyamide 56 salt solution, increasing the pressure in the reaction system to 2.3 MPa, degassing, maintaining the pressure with the temperature of the reaction system at the end of the pressure-maintenance being 255° C., reducing the pressure in the reaction system to 0.1 MPa with the temperature of the reaction system at the end of the pressure reduction being 270° C., and evacuating to a vacuum degree of −0.05 MPa with the temperature at the end of evacuation being 280° C. to obtain a low-viscosity polyamide 56 resin; wherein all the pressures are gauge pressures;

[0243] 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 moisture content of 500 ppm, and an amino content of 42.5 mmol/kg.

[0244] 2. Spinning:

[0245] (1) heating the low-viscosity polyamide 56 resin to a molten state to form a polyamide 56 melt, wherein the heating was carried out in a screw extruder, and the screw extruder was in particular divided into five heating zones, wherein the temperature of a first zone was 250° C., the temperature of a second zone was 275° C., the temperature of a third zone was 280° C., the temperature of a fourth zone was 295° C., and the temperature of a fifth zone was 305° C.; ejecting the polyamide 56 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 290° C., the pressure of the pack was 14 MPa and the drawing ratio of spinneret was 120;

[0246] (2) thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 230° C., and the slow cooling length was 40 mm; the cooling was performed with quench air, and the air speed was 1.1 m/s; the air temperature was 23° C.; and the humidity was 75%; the winding tension during winding the as-spun yarn into a shape was 160 cN; the winding speed was 3,200 m/min; and the winding overfeed ratio was 3.5%; the drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 5.6; the temperature of the first thermal setting was 225° C.; and the temperature of the second thermal setting was 235° C.

COMPARATIVE EXAMPLE 4

Polyamide 6 Industrial Yarn (933 dtex/140f)

[0247] The process comprised the following steps:

[0248] (1) heating the high-viscosity polyamide 6 resin into a molten state to form a polyamide 6 melt, wherein the heating was carried out in a screw extruder, and the screw extruder included in particular five heating zones, wherein the temperature of a first zone was 255° C., the temperature of a second zone was 270° C., the temperature of a third zone was 280° C., the temperature of a fourth zone was 290° C., and the temperature of a fifth zone was 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 moisture content of 400 ppm, and an amino content of 36.5 mmol/kg.

[0249] 2. Spinning the polyamide 6 melt into yarns, ejecting the polyamide 6 melt through the spinneret plate of the spinning beam to form an as-spun yarn; wherein the temperature of the spinning beam was 290° C., the pressure of the pack was 15 MPa and the drawing ratio of spinneret was 150;

[0250] 3. processing the as-spun yarn to obtain the polyamide 6 industrial yarn, wherein the processing comprised the steps of thermally insulating, cooling, spin finishing, drawing, and winding the as-spun yarn into a shape so as to obtain the polyamide 56 industrial yarn; wherein the thermal insulation was performed with a slow cooling device, the slow cooling temperature was 220° C., and the slow cooling length was 20 mm; the cooling was performed with quench air, and the air speed was 1.2 m/s; the air temperature was 22° C.; and the humidity was 70%;

[0251] the winding tension during winding the as-spun yarn into a shape was 90 cN; the winding speed was 3,500 m/min; and the winding overfeed ratio was 2.0%.

[0252] The drawing process was four-stage drawing process which was the same as that in Example 1, except that the total drawing ratio was 5.0; the temperature of the first thermal setting was 220° C.; and the temperature of the second thermal setting was 230° C. In the above Examples and Comparative Examples, the absolute value of the difference between the relative viscosity of the oil-free yarn and the relative viscosity of its original resin, the absolute value of the difference between the amino content of the oil-free yarn and the amino content of its original resin, the filament breakage (times/24 hrs) and the production yield (%) are shown in Table 1 below. The properties of the obtained polyamide 56 industrial yarn are shown in Table 2 below.

TABLE-US-00001 TABLE 1 Absolute value Absolute value of the difference of the difference Relative between the relative Amino Amino between the amino viscosity Relative viscosity of the oil- content of content of content of the oil- Filament of the viscosity of free yarn and the the original the oil- free yarn and the breakage Production original the oil- relative viscosity of resin free yarn amino content of (times/ yield No. resin free yarn its original resin (mmol/kg) (mmol/kg) its original resin 24 hrs) (%) Example 1 3.31 3.40 0.09 36.5 35.2 1.3 1 97.8 Example 2 3.52 3.57 0.05 33.5 33.0 0.5 1 96.7 Example 3 3.00 3.06 0.06 42.5 41.0 1.5 0 96.0 Example4 2.90 3.00 0.10 40.5 39.2 1.3 0 95.2 Example 5 3.60 3.63 0.03 46.5 45.3 1.2 1 96.3 Example 6 3.41 3.46 0.05 43.2 42.5 0.7 0 97.0 Example 7 3.21 3.20 0.01 38.5 39.0 0.5 0 98.5 Example 8 3.41 3.49 0.08 33.5 33.0 0.5 0 96.7 Example 9 3.61 3.66 0.05 34.5 32.0 2.5 1 96.3 Example 10 3.70 3.80 0.10 33.8 32.6 1.2 1 96.4 Example 11 3.29 3.37 0.08 36.5 35.0 1.5 1 95.8 Example 12 3.22 3.19 0.03 32.3 34.0 1.7 1 95.0 Example 13 3.39 3.46 0.07 32.5 30.7 1.8 0 97.2 Example 14 3.50 3.48 0.02 40.5 41.8 1.3 0 98.3 Example 15 3.38 3.40 0.02 42.5 41.2 1.3 0 97.0 Example 16 3.41 3.46 0.05 42.0 40.8 1.2 0 96.5 Example 17 3.42 3.50 0.08 42.5 41.4 1.1 0 98.5 Example 18 3.40 3.44 0.04 42.3 40.8 1.5 0 97.5 Comparative 3.32 3.17 0.15 36.5 42.0 5.5 4 90.8 Example 1 Comparative 3.31 2.90 0.41 36.5 43.4 6.9 12 80.5 Example 2 Comparative 2.50 2.37 0.13 42.5 47.8 5.3 15 83.4 Example 3 Comparative 3.30 3.28 0.02 36.5 39.0 2.5 3 93.0 Example 4

[0253] In the present invention, by reducing the viscosity of the oil-free yarn and the fluctuation range of the amino content, uniformity and stability of the polyamide 56 melt were increased, the filament breakage was reduced, and the spinnability were increased. The prepared polyamide 56 industrial yarn achieved a high yield of 95% or more, and had a filament breakage of 1 time or less every 24 hrs.

TABLE-US-00002 TABLE 2 180° C. * 4 hrs; 230° C. * 30 mins; Heat Resistant Heat Resistant Break Strength Break Strength Dry Heat Break elongation Shrinkage Orientation Retention Retention Shrinkage Strength at break in Boiling Crystallinity Degree No. Rate (%) Rate (%) (%) (cN/dtex) (%) Water (%) (%) (%) Example 1 92.2 91.6 5.2 8.5 23.9 5.8 72.6 82.5 Example 2 95.3 93.8 4.8 8.6 22.2 5.5 74.3 84.4 Example 3 92.8 91.6 5.3 8.6 20.8 5.2 74.7 84.5 Example 4 93.8 92.4 5.1 8.7 19.8 5.0 75.0 85.0 Example 5 96.2 95.7 4.6 8.8 17.5 4.8 76.4 86.2 Example 6 94.5 94.5 4.5 8.6 20.2 4.6 75.3 87.8 Example 7 96.9 95.5 4.2 8.8 21.5 4.3 76.8 88.2 Example 8 93.8 92.0 4.2 8.5 18.0 4.8 74.5 86.9 Example 9 91.5 90.8 5.3 8.6 22.8 4.7 73.9 85.3 Example 10 92.6 92.0 4.9 8.6 20.5 5.0 73.4 82.3 Example 11 93.8 93.5 5.2 8.5 19.8 5.5 74.3 84.8 Example 12 92.4 92.2 5.3 8.4 18.4 5.6 72.4 83.1 Example 13 94.2 93.8 4.7 8.7 21.2 4.9 76.0 82.6 Example 14 95.4 94.6 5.0 8.5 22.3 5.2 75.2 84.5 Example 15 94.7 93.9 4.6 8.6 21.0 4.5 74.9 87.5 Example 16 95.1 94.8 4.4 8.6 19.3 4.4 75.1 87.3 Example 17 94.5 93.1 4.7 8.5 22.2 4.8 74.9 83.5 Example 18 92.9 91.3 4.7 8.6 19.0 4.5 71.3 81.7 Comparative 70.5 68.5 8.0 7.6 20.0 8.2 68.5 72.5 Example 1 Comparative 85.6 82.9 7.0 6.3 22.6 8.1 63.2 70.7 Example 2 Comparative 82.2 80.7 7.5 6.0 23.5 8.5 65.8 72.5 Example 3 Comparative 68.2 65.5 8.8 7.5 21.4 9.0 69.0 75.8 Example 4

[0254] The present invention optimized the viscosity, oligomer content, molecular weight and its distribution, and moisture content of the polyamide 56 resin. Furthermore, the present invention optimized the spinning process of the polyamide 56 industrial yarn, improved its crystallinity and orientation degree, increased the setting temperature and winding overfeed ratio, and reduced the subsequent stress relaxation. The present invention thus provided a polyamide 56 industrial yarn with excellent mechanical properties and dimensional stability which has a break strength of 8.0 cN/dtex or more; an elongation at break of 26% or less; a dry heat shrinkage and a shrinkage in boiling water of 6% or less; a crystallinity of 70% or more; and an orientation degree of 80% or more.

[0255] The foregoing description of the embodiments was 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 can be readily made to these embodiments. The generic principles described herein can be applied to other embodiments without creative labor. Therefore, the present invention is not limited to the above-mentioned embodiments. 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 all fall within the protection scope of the present invention.