A heat-resistant low-hairiness polyamide 56 industrial yarn and its preparation method and application

Abstract

The present invention relates to the technical field of polyamide materials, and discloses a heat-resistant and low-hairiness polyamide 56 industrial yarn and its preparation method and application. The content of copper ions in the polyamide 56 industrial yarn is 55-110 ppm, further 60-100 ppm, and still further 65-80 ppm. The heat-resistant and low-hairiness polyamide 56 industrial yarn provided by the present invention has good heat resistance and less hairiness, and can meet the requirements of the high-end heat-resistant and low-hairiness industrial yarn field, especially the fields of tire cord and airbag yarn.

Description

Technical Field

[0001] The present invention relates to the technical field of polyamide materials, and particularly relates to a heat-resistant and low-hairiness polyamide 56 industrial yarn and its preparation method and application. Background Art

[0002] Polyester and polyamide industrial yarns have the characteristics of high strength, low elongation, good dimensional stability, fatigue resistance and aging resistance, etc., making them widely used in fields such as tire cord, canvas, conveyor belt, airbag, parachute, rope, safety belt, industrial filter cloth or tent.

[0003] There are two production processes for industrial yarns: one is the melt direct spinning method, and the other is the indirect spinning method of solid-phase viscosity increase of chips.

[0004] Polyamide 66 and polyethylene terephthalate glycol have been partially spun by the melt direct spinning method. Since polyamide 6 contains 8-10 wt% of monomers in the polymer, the monomers need to be removed through a monomer removal process. Currently, it cannot be directly melt-spun. It is necessary to first prepare a low-viscosity resin and then use solid-phase viscosity increase to prepare high-viscosity chips for producing industrial yarns.

[0005] Higher heat resistance performance requirements for industrial yarn materials in different application fields are currently achieved by blending with a heat stabilizer masterbatch or adding a heat-resistant agent during direct polymerization for spinning.

[0006] CN 110055602 A discloses a polyamide 56 high-strength industrial yarn and its preparation method, which uses conventional polyamide 56 chips for spinning without heat-resistant modification of the polyamide 56 chips. The prepared industrial yarn has poor heat resistance performance and cannot be applied in fields with high heat resistance requirements, such as sewing thread, tire cord, airbag yarn, release cloth, water cloth, etc. By adopting a high-speed winding process with a winding speed greater than 4000 m / min, the winding speed is high, and the residence time of the fiber on different hot rolls is relatively shortened, that is, the high-temperature setting time of the fiber is shortened. Secondly, by adopting a low-draft stretching process, the crystallization and orientation of the fiber are low, resulting in low fiber strength and poor dimensional stability of the prepared fiber.

[0007] CN 106868624 B discloses a polyamide 5X high-strength yarn and its preparation method. The breaking strength of the polyamide 5X high-strength yarn is 8.0-10.0 cN / dtex, and the breaking elongation is 10-15%. The breaking elongation of the polyamide 5X high-strength yarn is low, and its heat resistance performance also fails to meet the requirements for use in special fields.

[0008] CN 106835329 B discloses a polyamide 5X medium-strength filament and its preparation method. The breaking strength of the polyamide 5X medium-strength filament is 6.0 - 8.0 cN / dtex, and the breaking elongation is 20.8 - 25%. The breaking strength of the polyamide 5X medium-strength filament is on the low side, and its heat resistance also fails to meet the requirements for use in special fields.

[0009] For the fields of tire cord and airbag filament, in addition to heat resistance requirements, high requirements are also placed on fiber hairiness. For industrial yarns used for airbag filaments, the number of flyings should be ≤ 0.5 per (10,000 m * 1000 filaments).

[0010] Therefore, developing polyamide 56 industrial yarns with good heat resistance and low hairiness is a technical problem that urgently needs to be solved at present. Summary of the Invention

[0011] The first object of the present invention is to provide a polyamide 56 industrial yarn with excellent heat resistance and low hairiness. After being treated at 170 °C for 2 h, the heat-resistant breaking strength retention rate of the polyamide 56 industrial yarn is ≥ 93%; after being treated at 180 °C for 4 h, the heat-resistant breaking strength retention rate is ≥ 92%; after being treated at 150 °C for 72 h, the heat-resistant breaking strength retention rate is ≥ 85%; after being treated at 205 °C for 16 h, the heat-resistant breaking strength retention rate is ≥ 65%; after being treated at 230 °C for 30 min, the heat-resistant breaking strength retention rate is ≥ 92%. At the same time, the hairiness of the polyamide 56 industrial yarn is ≤ 2 per 10 kg cake.

[0012] The second object of the present invention is to provide a polyamide 56 industrial yarn with good mechanical properties and dimensional stability at the same time. The breaking strength of the polyamide 56 industrial yarn is 6.0 - 9.5 cN / dtex, the breaking elongation is 8 - 26%, the unevenness rate of evenness is ≤ 1.5%, the initial modulus is 40 - 65 cN / dtex, the dry heat shrinkage rate is ≤ 6.0%, and the boiling water shrinkage rate is ≤ 9.0%.

[0013] The third object of the present invention is to provide a preparation method for heat-resistant and low-hairiness polyamide 56 industrial yarn.

[0014] By using a high-viscosity polyamide 56 resin with appropriate viscosity and moisture content, selecting a suitable heat stabilizer and controlling the addition content, adjusting the combination of the filter screen and metal sand in the spinning pack, and optimizing the spinning process and spinning finish, the copper ion retention rate in the prepared polyamide 56 industrial yarn is preferably ≥ 90%, the loss of copper ions is small, the service life of the pack is long, the heat resistance is greatly improved, the hairiness is less, and the production rate is high.

[0015] The fourth object of the present invention is to provide an application of heat-resistant and low-hairiness polyamide 56 industrial yarn.

[0016] The beneficial effects that can be achieved by adopting the technical solution of the present invention include:

[0017] First, the production raw materials of the heat-resistant and low-hairiness polyamide 56 industrial yarn of the present invention are made by biological methods, which are green materials, do not rely on petroleum resources and do not cause serious pollution to the environment, can reduce carbon dioxide emissions, and reduce the generation of the greenhouse effect.

[0018] Second, the heat-resistant and low-hairiness polyamide 56 industrial yarn of the present invention has good heat resistance and less hairiness, and can meet the requirements of the high-end heat-resistant and low-hairiness industrial yarn field, especially the tire cord and airbag yarn fields.

[0019] Third, the copper ion heat stabilizer in the polyamide 56 industrial yarn of the present invention can be added during polymerization or injected online in the form of a heat-resistant masterbatch before polymerization melt pelletizing, which is flexible and convenient. By selecting a suitable heat stabilizer and controlling the addition content, adjusting the combination of the filter screen and metal sand in the spinning pack, the loss of copper ions in the prepared polyamide 56 industrial yarn is small, the retention rate is high, and the copper ions are evenly distributed in the polyamide 56 melt or resin. The prepared industrial yarn has more uniform mechanical properties, smaller CV% fluctuation and evenness, and even with a small addition amount, the heat resistance is still greatly improved, the hairiness is less, the production rate is high, and the service life of the pack is longer.

[0020] Fourth, the production of the polyamide 56 industrial yarn of the present invention uses a high-viscosity polyamide 56 resin with appropriate viscosity and moisture content. At the same time, the spinning process and spinning finish are optimized, and the crude oil oiling method is adopted. During the spinning process, stable production can be achieved, and the phenomena of broken single filaments and less hairiness are extremely rare. The production rate is greatly increased, and the prepared polyamide 56 industrial yarn has good mechanical properties and heat resistance.

[0021] Fifth, the heat-resistant and low-hairiness polyamide 56 industrial yarn of the present invention can be produced by using conventional polyamide 6 and polyamide 66 industrial yarn equipment, without the need to transform the spinning equipment. By optimizing the quality of the polyamide 56 resin and the spinning process, the production rate can be increased and the production cost can be reduced, bringing great benefits to spinning enterprises. Detailed implementation manners

[0022] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0023] To achieve the above object, a first aspect of the present invention provides a heat-resistant low-hairiness polyamide 56 industrial yarn, wherein the content of copper ions in the polyamide 56 industrial yarn is 55-110 ppm, further 60-100 ppm, and still further 65-80 ppm.

[0024] In some specific embodiments of the present invention, after the polyamide 56 industrial yarn is treated at 170 °C for 2 h, the heat-resistant breaking strength retention rate is ≥93%, further ≥95%, and still further ≥97%.

[0025] In some specific embodiments of the present invention, after the polyamide 56 industrial yarn is treated at 180 °C for 4 h, the heat-resistant breaking strength retention rate is ≥92%, further ≥93%, and still further ≥94%.

[0026] In some specific embodiments of the present invention, after the polyamide 56 industrial yarn is treated at 150 °C for 72 h, the heat-resistant breaking strength retention rate is ≥85%, further ≥88%, and still further ≥90%.

[0027] In some specific embodiments of the present invention, after the polyamide 56 industrial yarn is treated at 205 °C for 16 h, the heat-resistant breaking strength retention rate is ≥65%, further ≥68%, and still further ≥70%.

[0028] In some specific embodiments of the present invention, after the polyamide 56 industrial yarn is treated at 230 °C for 30 min, the heat-resistant breaking strength retention rate is ≥92%, further ≥94%, and still further ≥95%.

[0029] In some preferred embodiments of the present invention, the breaking strength of the polyamide 56 industrial yarn is 6.0-9.5 cN / dtex, further 6.5-9.2 cN / dtex, and still further 7.0-8.8 cN / dtex.

[0030] In some preferred embodiments of the present invention, the breaking elongation rate of the polyamide 56 industrial yarn is 8-26%, further 12-24%, and still further 14-22%.

[0031] In some preferred embodiments of the present invention, the evenness variation coefficient of the polyamide 56 industrial yarn is ≤1.5%, further ≤1.3%, and still further ≤1.1%.

[0032] In some preferred embodiments of the present invention, the fineness of the polyamide 56 industrial yarn is 120-3000 dtex, further 150-2600 dtex, and still further 200-2000 dtex.

[0033] In some preferred embodiments of the present invention, the number of holes of the polyamide 56 industrial yarn is 18 - 288f, preferably 24 - 140f, more preferably 36 - 105f, and even more preferably 48 - 86f.

[0034] In some preferred embodiments of the present invention, the initial modulus of the polyamide 56 industrial yarn is 40 - 65 cN / dtex, further 44 - 60 cN / dtex, and even more 48 - 55 cN / dtex.

[0035] In some preferred embodiments of the present invention, the dry heat shrinkage rate of the polyamide 56 industrial yarn is ≤6.0%, further ≤5.5%, and even more ≤5.0%.

[0036] In some preferred embodiments of the present invention, the boiling water shrinkage rate of the polyamide 56 industrial yarn is ≤9.0%, further ≤8.0%, and even more ≤7.0%.

[0037] In some preferred embodiments of the present invention, the component replacement cycle of the polyamide 56 industrial yarn is ≥25 days, further ≥28 days, and even more ≥30 days.

[0038] In some preferred embodiments of the present invention, the number of broken single filaments of the polyamide 56 industrial yarn is ≤2 times / 1 spinning position / 24 h, further ≤1 time / 1 spinning position / 24 h, and even more ≤0 times / 1 spinning position / 24 h.

[0039] In some preferred embodiments of the present invention, the production rate of the polyamide 56 industrial yarn is ≥96%, further ≥97%, and even more ≥98%.

[0040] In some preferred embodiments of the present invention, the hairiness of the polyamide 56 industrial yarn is ≤2 pieces / 10 kg cake, further ≤1 piece / 10 kg cake, and even more ≤0 pieces / 10 kg cake.

[0041] The second aspect of the present invention provides a method for preparing the heat-resistant and low-hairiness polyamide 56 industrial yarn as described above, and the method includes:

[0042] (1) Heating the high-viscosity polyamide 56 resin to a molten state to obtain a polyamide 56 melt;

[0043] (2) Transporting the polyamide 56 melt through a melt pipe to a spinning box for wire drawing to form a nascent yarn;

[0044] (3) Performing heat preservation, cooling, oiling, pre-networking, multi-stage stretching, tension heat setting, two-stage relaxation heat setting, main networking, and winding on the nascent yarn to obtain the heat-resistant and low-hairiness polyamide 56 industrial yarn.

[0045] According to a preferred embodiment of the present invention, in step (1), the content of copper ions in the high-viscosity polyamide 56 resin is 55-130 ppm, further 65-110 ppm, and still further 70-90 ppm.

[0046] According to a preferred embodiment of the present invention, in step (1), the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid is 2.9-4.0, further 3.1-3.8, and still further 3.3-3.6.

[0047] According to a preferred embodiment of the present invention, in step (1), the water content of the high-viscosity polyamide 56 resin is 280-530 ppm, further 320-500 ppm, and still further 350-450 ppm.

[0048] In some specific embodiments of the present invention, in step (1), the high-viscosity polyamide 56 resin contains a heat stabilizer, and the heat stabilizer is selected from one or more of copper acetate, cuprous iodide, potassium iodide, and potassium bromide. Preferably, it is a compound containing copper and a halide compound in combination, that is, copper acetate or cuprous iodide is combined with potassium iodide and / or potassium bromide.

[0049] Further, the heat stabilizer includes a composition of copper acetate and potassium iodide, or a composition of cuprous iodide and potassium iodide, or a composition of cuprous iodide, potassium iodide, and potassium bromide; when the heat stabilizer is a composition of cuprous iodide, potassium iodide, and potassium bromide, the mass ratio of potassium iodide to potassium bromide is (1:4):(4:1), such as 1:1, etc.

[0050] Further, the heat stabilizer is added during the polymerization process, or is injected online in the form of a heat-resistant masterbatch before melt pelletization of the polymerization melt.

[0051] In the present invention, the production raw materials of the high-viscosity polyamide 56 resin include 1,5-pentanediamine and adipic acid; or a polyamide resin 56 obtained by polymerizing 1,5-pentanediamine and adipic acid as monomers. Among them, the pentanediamine can be 1,5-pentanediamine from a chemical source or a biological source, and preferably 1,5-pentanediamine from a biological source.

[0052] In the present invention, the high-viscosity polyamide 56 resin is obtained by first preparing a low-viscosity polyamide 56 resin and then obtaining the high-viscosity polyamide 56 resin through solid-phase polycondensation. In the present invention, the solid-phase polycondensation means that by high-temperature drying, water is removed at the same time, and the polycondensation reaction continues to obtain the high-viscosity polyamide 56 resin.

[0053] In some specific embodiments of the present invention, the preparation method of the high-viscosity polyamide 56 resin includes the following steps:

[0054] (1-1) Under an inert gas or vacuum condition, 1,5-pentanediamine, adipic acid and water are mixed evenly to obtain a polyamide 56 salt solution; wherein, the molar ratio of the 1,5-pentanediamine to the adipic acid is (1-1.1):1;

[0055] (1-2) The polyamide 56 salt solution is heated, the pressure in the reaction system rises to 1.5-2.5 MPa, exhaust gas, maintain the pressure, and the temperature of the reaction system at the end of pressure maintenance is 230-265 °C; then the pressure is reduced to make the pressure in the reaction system drop to 0-0.2 MPa, and the temperature of the reaction system after the pressure reduction is 250-285 °C; evacuate to a vacuum degree of -(0.01-0.1) MPa, and the temperature after evacuation is 265-295 °C. The pressure is gauge pressure to obtain a polyamide 56 melt;

[0056] (1-3) The polyamide 56 melt is pelletized to obtain a low-viscosity polyamide 56 resin;

[0057] Among them, a heat stabilizer is added during the polymerization of 1,5-pentanediamine and adipic acid in step (1-1), and the addition amount of the heat stabilizer accounts for 50-3200 ppm of the total weight of the production raw materials, preferably 200-2800 ppm; or the heat stabilizer is injected online in the form of a heat-resistant masterbatch before the polymerization melt is pelletized in step (1-3). The content of copper ions in the heat-resistant masterbatch is 1-10 wt%, preferably 2-8 wt%, more preferably 3-6 wt%; the addition amount of the heat-resistant masterbatch accounts for 0.05-2.0 wt% of the total weight of the production raw materials, preferably 0.08-1.5 wt%, more preferably 0.12-1.0 wt%;

[0058] (1-4) The low-viscosity polyamide 56 resin is prepared into a high-viscosity polyamide 56 resin by solid-phase polycondensation. The temperature of the solid-phase viscosity increase is 150-200 °C, and the drying time of the solid-phase viscosity increase is 10-50 h.

[0059] In the present invention, the preparation method of the heat-resistant masterbatch includes: subjecting the heat-resistant masterbatch matrix polyamide material to vacuum drying and then grinding it into powder; mixing the powder obtained above with a heat stabilizer and other additives in proportion, and performing twin-screw melt extrusion granulation to obtain the heat-resistant masterbatch. The heat-resistant masterbatch matrix material includes any one or a combination of several of polyamide 6, polyamide 56, polyamide 66, polyamide 510, and polyamide 610, preferably polyamide 6, polyamide 56, and polyamide 510, and more preferably polyamide 6 and polyamide 56; the other additives include any one or several of a matting agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a crystallization nucleating agent, a fluorescent whitening agent, and an antistatic agent; the addition amount of the other additives accounts for 0.01-5 wt% of the total weight of the production raw materials. The content of copper ions in the high-viscosity polyamide 56 resin of the present invention is obtained by controlling the addition amount of the heat stabilizer.

[0060] In some specific embodiments of the present invention, the heating in step (1) is carried out in a screw extruder, and the screw extruder is divided into five zones for heating; wherein, the temperature of zone 1 is 260-290 °C, the temperature of zone 2 is 270-300 °C, the temperature of zone 3 is 280-310 °C, the temperature of zone 4 is 290-310 °C, and the temperature of zone 5 is 280-300 °C; and / or

[0061] The wire drawing in step (2) is to extrude the polyamide 56 melt through the spinneret of the spinning box to form the initial filament; and / or

[0062] The temperature of the spinning box is 282-294 °C, further 284-292 °C, and even further 286-290 °C; and / or

[0063] The pressure of the spinning assembly in the spinning box is 10-20 MPa, further 12-18 MPa, and even further 13-16 MPa.

[0064] According to some preferred embodiments of the present invention, the specification of the filter screen in the spinning assembly is 100-600 mesh, further 200-500 mesh, and even further 300-450 mesh; and / or

[0065] The specification of the metal sand in the spinning assembly is 40-120 mesh, further 45-100 mesh, and even further 60-80 mesh;

[0066] Furthermore, by adjusting the combination mode of the filter screen and the metal sand, the retention rate of copper ions in the polyamide 56 industrial yarn is ≥82%, further ≥85%, and even further ≥90%.

[0067] In some specific embodiments of the present invention, in step (3), slow cooling is carried out by a slow cooling device, the slow cooling height is 240 - 320 mm, further 260 - 300 mm; the slow cooling temperature is 260 - 320 °C, further 280 - 310 °C. In the present invention, the slow cooling device is a heat sleeve closely adjacent to the lower part of the spinneret to ensure uniform and slow cooling of the nascent filament. The length and temperature of the heat sleeve vary with the specifications of the spinneret and the fineness of the filament bundle. Among them, the slow cooling height refers to the thickness of the heat sleeve, and the slow cooling temperature refers to the ambient temperature around the filament bundle.

[0068] In the present invention, the cooling is carried out by side blowing, the wind speed is 0.5 - 0.8 m / s, further 0.6 - 0.7 m / s; the air temperature is 16 - 22 °C, further 18 - 20 °C.

[0069] In the present invention, the oiling is carried out by using crude oil agent for oiling, the oiling rate is 0.9 - 1.2 wt%, and the dynamic viscosity of the crude oil agent is ≤ 150 mm 2 / s, further ≤ 120 mm 2 / s, still further ≤ 90 mm 2 / s. The crude oil agent is selected from one or more of DELION F - 8740 - N (Takemoto Oil & Fat Co., Ltd.), HQ - 68 - H (Takemoto Oil & Fat (Suzhou) Co., Ltd.), DELION HQ - 635 (Takemoto Oil & Fat (Suzhou) Co., Ltd.), Lupert TM A275 (provided by Luda Technology), N - 350 (provided by Matsumoto Yushi Yakuhin Co., Ltd., Japan), N - 353 (provided by Matsumoto Yushi Yakuhin Co., Ltd., Japan), LIMANOL TL8E (provided by German double S (Schill + Seilacher)), NEO TEX - 903(A) (Shanghai Bikaimei Chemical Co., Ltd.), D - 3088 (provided by Nantong Hengrun Chemical Industry Co., Ltd.), dakaoNeat crude oil type oil agent (provided by German Dako AG), TCP - 80 polyamide industrial yarn / cord oil agent (provided by Tianjin Polytechnic University Textile Auxiliaries Co., Ltd.), TC1152 (provided by German Zschimmer & Schwarz), TC1355 (provided by German Zschimmer & Schwarz) and TC - 14686 (provided by GOULSTON TECHNOLOGIES, Inc., 700 North Johnson St., Monroe, NC 28110). Further preferably, it is at least one of DELION F - 8740 - N, HQ - 68 - H, DELION HQ - 635, N - 353, TC1355 and Lupert TM A275.

[0070] In the present invention, the pressure of the pre-network is 1 - 2.5 bar, further preferably 1.5 - 2.0 bar.

[0071] In the present invention, the stretching process is carried out using 5 or more pairs of hot rollers, preferably 6 pairs of hot rollers, and is stretched in five stages. The stretching process is as follows: The as-spun filament after oiling is first fed into the first pair of hot rollers, and the first-stage pre-stretching is carried out between the first pair of hot rollers and the second pair of hot rollers. Then, the second-stage main stretching is carried out between the second pair of hot rollers and the third pair of hot rollers, and the third-stage main stretching and tension heat setting are carried out between the third pair of hot rollers and the fourth pair of hot rollers. The fourth-stage sub-stretching and the first relaxation heat setting are carried out between the fourth pair of hot rollers and the fifth pair of hot rollers. Then, the fifth-stage sub-stretching and the second relaxation heat setting are carried out between the fifth pair of hot rollers and the sixth pair of hot rollers. Finally, winding is carried out using a winding head.

[0072] Among them, the speed of the first pair of hot rollers is 400 - 800 m / min, preferably 450 - 750 m / min; the temperature is 20 - 70 °C, preferably 30 - 60 °C; and / or, the speed of the second pair of hot rollers is 450 - 950 m / min, preferably 500 - 900 m / min; the temperature is 80 - 150 °C, preferably 100 - 130 °C; and / or, the speed of the third pair of hot rollers is 1500 - 2500 m / min, preferably 1700 - 2300 m / min; the temperature is 100 - 190 °C, preferably 130 - 180 °C; and / or, the speed of the fourth pair of hot rollers is 2400 - 3200 m / min, preferably 2500 - 3100 m / min; the temperature is 180 - 230 °C, preferably 190 - 220 °C; and / or, the speed of the fifth pair of hot rollers is 2300 - 3100 m / min, preferably 2400 - 3000 m / min; the temperature is 160 - 220 °C, preferably 170 - 200 °C; and / or, the speed of the sixth pair of hot rollers is 2200 - 3000 m / min, preferably 2300 - 2900 m / min; the temperature is 140 - 210 °C, preferably 150 - 180 °C; and / or

[0073] The stretching multiple of the first-stage stretching is 1.0 - 1.2, preferably 1.05 - 1.15; and / or, the stretching multiple of the second-stage stretching is 3.0 - 4.0, preferably 3.2 - 3.8; and / or, the stretching multiple of the third-stage stretching is 1.3 - 1.6, preferably 1.35 - 1.5; and / or, the stretching multiple of the fourth-stage stretching is 0.9 - 1.0, preferably 0.94 - 0.98; and / or, the stretching multiple of the fifth-stage stretching is 0.9 - 1.0, preferably 0.92 - 0.95; and / or, the total stretching multiple of the stretching is 4.5 - 6.0, preferably 4.8 - 5.5; and / or

[0074] The main network pressure is 2.5 - 4.5 bar, preferably 3.0 - 3.5 bar; and / or

[0075] The winding speed is 2200 - 3000 m / min, preferably 2400 - 2800 m / min, more preferably 2500 - 2600 m / min; and / or

[0076] The overfeed ratio of winding is 0.8 - 5%, preferably 1 - 4%, more preferably 1.5 - 3%.

[0077] Therefore, the third aspect of the present invention provides an application of the heat-resistant low-hairiness polyamide 56 industrial yarn as described above in the fields of tire cord, airbag yarn, release cloth, sewing thread, water cloth, canvas, safety belt, rope, fishing net, industrial filter cloth, conveyor belt, parachute, tent, luggage, etc.

[0078] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, various raw materials used can be obtained from commercial channels.

[0079] The characteristics of the products obtained in the following examples and comparative examples are measured according to the following methods:

[0080] (1) Denier: Measured according to GB / T 14343.

[0081] (2) Tensile strength at break: Measured according to GB / T 14344 - 2008.

[0082] (3) Elongation at break: Measured according to GB / T 14344 - 2008.

[0083] (4) Retention rate of heat-resistant tensile strength: Retention rate of heat-resistant tensile strength = (tensile strength after heat treatment / tensile strength before heat treatment) * 100%, the tensile strength is measured according to GB / T 14344 - 2008, and the heat treatment equipment is an oven and a winding frame.

[0084] (5) Dry heat shrinkage rate: Executed according to the provisions of FZ / T 50004, and the heat treatment temperature is 180 °C.

[0085] (6) Boiling water shrinkage rate: Among them, the measurement of the boiling water shrinkage rate refers to GB / 6505 - 2008 "Test method for heat shrinkage rate of chemical fiber filaments", and the boiling water shrinkage rate = ((length before heat treatment - length after heat treatment) / length before heat treatment) * 100%.

[0086] (7) Relative viscosity: The relative viscosity of the polyamide 56 oil-free filament and the resin was measured by the concentrated sulfuric acid method using an Ubbelohde viscometer, and the steps are as follows: accurately weigh 0.5±0.0002 g of the dried polyamide 56 resin or its staple fiber sample, add 50 mL of concentrated sulfuric acid (96%) to dissolve it, and measure and record the flow time t of the concentrated sulfuric acid in a constant temperature water bath at 25°C. 0 and the flow time t of the polyamide 56 chips or its staple fiber sample solution.

[0087] The relative viscosity calculation formula is: relative viscosity VN = t / t 0 ; t-solution flow time; t 0 -Solvent flow time.

[0088] (8) Moisture content: measured by Karl Fischer titrator.

[0089] (9) Single filament breakage (number of times / 24h): manually counted.

[0090] (10) Production rate: Production rate = (the number of polyamide 56 finished fibers prepared / the total amount of polyamide 56 resin input) * 100%.

[0091] (11) Copper ion content: measured by element analyzer.

[0092] (12) Copper ion retention rate: Copper ion retention rate = (copper ion content in polyamide 56 industrial yarn / copper ion content in polyamide 56 resin)*100%.

[0093] (13) Unevenness of yarn dryness: measured according to the method of GB / T 14346-93.

[0094] (14) Oil dynamic viscosity: measured in accordance with the national standard GB / T 265-1988 “Method for determination of kinematic viscosity and calculation of dynamic viscosity of petroleum products”.

[0095] Example 1

[0096] Preparation of High Viscosity Polyamide 56 Resin

[0097] (1-1) Under nitrogen conditions, 1,5-pentanediamine, adipic acid and water are uniformly mixed, and a heat stabilizer is added to prepare a polyamide 56 salt solution with a concentration of 50%; wherein the molar ratio of the 1,5-pentanediamine to the adipic acid is 1.06:1; the heat stabilizer is a compound of cupric acetate and potassium iodide, the amount of cupric acetate added accounts for 220 ppm of the total weight of the production raw materials, and the amount of potassium iodide added accounts for 2000 ppm of the total weight of the production raw materials;

[0098] (1-2) Heat the polyamide 56 salt solution until the pressure in the reaction system rises to 1.75 MPa, exhaust the gas, maintain the pressure, and the temperature of the reaction system at the end of pressure maintenance is 255 °C; then reduce the pressure to make the pressure in the reaction system drop to 0.1 MPa, and the temperature of the reaction system after pressure reduction is 260 °C; evacuate to a vacuum degree of -0.06 MPa, and the temperature after evacuation is 282 °C. The pressure is gauge pressure to obtain polyamide 56 melt;

[0099] (1-3) Granulate the polyamide 56 melt to obtain low-viscosity polyamide 56 resin;

[0100] (1-4) The low-viscosity polyamide 56 resin is prepared into high-viscosity polyamide 56 resin by solid-phase polycondensation. The temperature of the solid-phase polycondensation is 160 °C, and the drying time for solid-phase viscosity increase is 20 h.

[0101] The content of copper ions in the obtained high-viscosity polyamide 56 resin is 70 ppm, the relative viscosity of 96% sulfuric acid is 3.3, and the moisture content is 350 ppm.

[0102] Preparation of polyamide 56 industrial yarn

[0103] (1) Heat the high-viscosity polyamide 56 resin prepared above to the molten state to obtain polyamide 56 melt;

[0104] (2) Transport the polyamide 56 melt to the spinning box through a melt pipeline for wire drawing to form a nascent filament;

[0105] (3) Insulate, cool, oil, pre-network, multi-stage stretch, tension heat set, two-stage relaxation heat set, main network, and wind up the nascent filament to obtain heat-resistant low-hairiness polyamide 56 industrial yarn.

[0106] The heating in step (1) is carried out in a screw extruder, and the screw extruder is divided into five zones for heating; among them, the temperature of zone 1 is 275 °C, the temperature of zone 2 is 285 °C, the temperature of zone 3 is 290 °C, the temperature of zone 4 is 295 °C, and the temperature of zone 5 is 295 °C.

[0107] The wire drawing in step (2) is to eject the polyamide 56 melt through the spinneret of the spinning box to form the nascent filament.

[0108] The temperature of the spinning box is 290 °C, and the pressure of the spinning component in the spinning box is 15 MPa.

[0109] The filter screen specification in the spinning component is 350 mesh, and the metal sand specification is 60 mesh.

[0110] The heat preservation in step (3) adopts a slow cooling device, the slow cooling height is 300 mm, and the slow cooling temperature is 300 °C.

[0111] The cooling is carried out by side blowing, the wind speed is 0.58 m / s, and the wind temperature is 20 °C.

[0112] The oiling is carried out by using the original oil agent, the oiling rate is 1.0 wt%, and the original oil agent is selected from DELION F-8740-N, and the dynamic viscosity of the original oil is 90 mm 2 / s.

[0113] The pre-network pressure is 1.5 bar.

[0114] In the stretching process, 6 pairs of hot rolls are used and stretched in five stages. The stretching process is as follows: the as-spun yarn after oiling is first fed into the first pair of hot rolls, and the first-stage pre-stretching is carried out between the first pair of hot rolls and the second pair of hot rolls, then the second-stage main stretching is carried out between the second pair of hot rolls and the third pair of hot rolls, the third-stage main stretching and tension heat setting are carried out between the third pair of hot rolls and the fourth pair of hot rolls, the fourth-stage sub-stretching and the first relaxation heat setting are carried out between the fourth pair of hot rolls and the fifth pair of hot rolls, and then the fifth-stage sub-stretching and the second relaxation heat setting are carried out between the fifth pair of hot rolls and the sixth pair of hot rolls; finally, winding is carried out by using a winding head.

[0115] Among them, the speed of the first pair of hot rolls is 550 m / min and the temperature is 35 °C; the speed of the second pair of hot rolls is 600 m / min and the temperature is 90 °C; the speed of the third pair of hot rolls is 1800 m / min and the temperature is 180 °C; the speed of the fourth pair of hot rolls is 2800 m / min and the temperature is 210 °C; the speed of the fifth pair of hot rolls is 2750 m / min and the temperature is 200 °C; the speed of the sixth pair of hot rolls is 2700 m / min and the temperature is 180 °C;

[0116] The stretching multiple of the first-stage stretching is 1.09; the stretching multiple of the second-stage stretching is 3.0; the stretching multiple of the third-stage stretching is 1.56; the stretching multiple of the fourth-stage stretching is 0.98; the stretching multiple of the fifth-stage stretching is 0.98; the total stretching multiple of the stretching is 4.9; the main network pressure is 3.0 bar; the winding speed is 2650 m / min, and the winding overfeed ratio is 1.85%.

[0117] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0118] Example 2

[0119] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the high-viscosity polyamide 56 resin, the copper ion content in the prepared high-viscosity polyamide 56 resin was adjusted to 55 ppm by controlling the addition amount of the heat stabilizer; other steps were the same as in Example 1.

[0120] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0121] Example 3

[0122] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the high-viscosity polyamide 56 resin, the copper ion content in the prepared high-viscosity polyamide 56 resin was adjusted to 65 ppm by controlling the addition amount of the heat stabilizer; other steps were the same as in Example 1.

[0123] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0124] Example 4

[0125] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the high-viscosity polyamide 56 resin, the copper ion content in the prepared high-viscosity polyamide 56 resin was adjusted to 80 ppm by controlling the addition amount of the heat stabilizer; other steps were the same as in Example 1.

[0126] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0127] Example 5

[0128] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the high-viscosity polyamide 56 resin, the copper ion content in the prepared high-viscosity polyamide 56 resin was adjusted to 95 ppm by controlling the addition amount of the heat stabilizer; other steps were the same as in Example 1.

[0129] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0130] Example 6

[0131] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the high-viscosity polyamide 56 resin, the copper ion content in the prepared high-viscosity polyamide 56 resin was adjusted to 110 ppm by controlling the addition amount of the heat stabilizer; other steps were the same as in Example 1.

[0132] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0133] Example 7

[0134] Preparation of high-viscosity polyamide 56 resin

[0135] (1-1) Under nitrogen atmosphere, 1,5-pentanediamine, adipic acid and water were mixed evenly to obtain a 65% polyamide 56 salt solution; wherein, the molar ratio of 1,5-pentanediamine to adipic acid was 1.15:1;

[0136] (1-2) The polyamide 56 salt solution was heated, and the pressure in the reaction system rose to 2.3 MPa. Then the gas was discharged and the pressure was maintained. The temperature of the reaction system at the end of pressure maintenance was 265 °C; then the pressure was reduced to make the pressure in the reaction system drop to 0 MPa. The temperature of the reaction system after pressure reduction was 275 °C; the vacuum was pumped to a vacuum degree of -0.04 MPa, and the temperature after vacuum pumping was 285 °C. The pressure was gauge pressure, and polyamide 56 melt was obtained;

[0137] (1-3) Before pelletizing the polyamide 56 melt, heat-resistant masterbatch was injected through the masterbatch on-line adding device, then mixed evenly with the polyamide 56 melt through a melt dynamic mixer, and finally pelletized to obtain low-viscosity polyamide 56 resin;

[0138] Among them, the content of copper ions in the heat-resistant masterbatch was 5.0 wt%, and the addition amount of the heat-resistant masterbatch accounted for 0.15 wt% of the total weight of the production raw materials. The matrix material of the heat-resistant masterbatch was polyamide 56. The preparation method of the heat-resistant masterbatch included the following steps: (a) The matrix material polyamide 56 was vacuum dried and then ground into powder; (b) The powder obtained in step (a) was mixed with a composition of heat stabilizer cuprous iodide and potassium iodide, lubricant wax OP, and antioxidant 168 in proportion, and melt extruded and pelletized by a twin-screw. The processing temperature of each zone was 251 °C in zone 1, 264 °C in zone 2, 269 °C in zone 3, 273 °C in zone 4, 276 °C in zone 5, the screw speed was 250 r / min, and the filter screen was 150 meshes, so as to obtain polyamide 56 heat-resistant masterbatch;

[0139] (1-4) The low-viscosity polyamide 56 resin was used to prepare high-viscosity polyamide 56 resin by solid-phase polycondensation. The temperature of solid-phase viscosity increase was 165 °C, and the drying time of solid-phase viscosity increase was 25 h.

[0140] The content of copper ions in the obtained high-viscosity polyamide 56 resin was 70 ppm, the relative viscosity of 96% sulfuric acid was 3.3, and the water content was 350 ppm.

[0141] Preparation of polyamide 56 industrial yarn

[0142] (1) The high-viscosity polyamide 56 resin prepared above was heated to the molten state to obtain polyamide 56 melt;

[0143] (2) Feed the polyamide 56 melt into a spinning box through a melt pipeline for wire drawing to form a nascent fiber.

[0144] (3) Keep the nascent fiber warm, cool it, apply oil, pre-network it, perform multi-stage stretching, tension heat setting, two-stage relaxation heat setting, main network formation, and winding to obtain a heat-resistant and low-hairiness polyamide 56 industrial fiber.

[0145] During the preparation process of the polyamide 56 industrial fiber, the process conditions involved are the same as those in Example 1.

[0146] The performance index parameters of the polyamide 56 industrial fiber prepared in this example are shown in Table 1.

[0147] Example 8

[0148] Prepare the polyamide 56 industrial fiber by the same method as in Example 7, except that during the preparation process of the high-viscosity polyamide 56 resin, by adjusting the addition amount of the heat stabilizer, the copper ion content in the prepared high-viscosity polyamide 56 resin is 80 ppm; other steps are the same as in Example 7.

[0149] The performance index parameters of the polyamide 56 industrial fiber prepared in this example are shown in Table 1.

[0150] Example 9

[0151] Prepare the polyamide 56 industrial fiber by the same method as in Example 7, except that during the preparation process of the high-viscosity polyamide 56 resin, the heat stabilizer is a compound of cuprous iodide, potassium iodide, and potassium bromide, where the mass ratio of potassium iodide to potassium bromide is 1:1, and by adjusting the addition amount of the heat stabilizer, the copper ion content in the prepared high-viscosity polyamide 56 resin is 80 ppm; other steps are the same as in Example 7.

[0152] The performance index parameters of the polyamide 56 industrial fiber prepared in this example are shown in Table 1.

[0153] Example 10

[0154] Prepare the polyamide 56 industrial fiber by the same method as in Example 1, except that during the preparation process of the polyamide 56 industrial fiber, the crude oil agent is selected from DELION HQ-635, and the dynamic viscosity of the crude oil is 95 mm 2 / s; other steps are the same as in Example 1.

[0155] The performance index parameters of the polyamide 56 industrial fiber prepared in this example are shown in Table 1.

[0156] Example 11

[0157] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the polyamide 56 industrial yarn, the crude oil sizing agent was selected from Lupert TM A275, and the dynamic viscosity of the crude oil was 18 mm 2 / s; other steps were the same as in Example 1.

[0158] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0159] Example 12

[0160] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the high-viscosity polyamide 56 resin, no heat stabilizer was added, so that the copper ion content in the prepared high-viscosity polyamide 56 resin was 0 ppm; other steps were the same as in Example 1.

[0161] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0162] Example 13

[0163] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the high-viscosity polyamide 56 resin, by adjusting the addition amount of the heat stabilizer, the copper ion content in the prepared high-viscosity polyamide 56 resin was 40 ppm; other steps were the same as in Example 1.

[0164] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0165] Example 14

[0166] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the high-viscosity polyamide 56 resin, by adjusting the addition amount of the heat stabilizer, the copper ion content in the prepared high-viscosity polyamide 56 resin was 150 ppm; other steps were the same as in Example 1.

[0167] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0168] Example 15

[0169] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the polyamide 56 industrial yarn, the filter screen specification in the spinning pack was 800 mesh; other steps were the same as in Example 1.

[0170] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0171] Example 16

[0172] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the polyamide 56 industrial yarn, the filter screen in the spinning pack had a specification of 1200 mesh; other steps were the same as in Example 1.

[0173] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0174] Example 17

[0175] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the polyamide 56 industrial yarn, the metal sand in the spinning pack had a specification of 130 mesh; other steps were the same as in Example 1.

[0176] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0177] Example 18

[0178] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the polyamide 56 industrial yarn, there was no slow cooling device; other steps were the same as in Example 1.

[0179] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0180] Example 19

[0181] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the polyamide 56 industrial yarn, emulsion oiling was used, and the crude oil agent was selected from DELION HQ-623, and the oil agent concentration was adjusted to 15 wt%; other steps were the same as in Example 1.

[0182] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0183] Example 20

[0184] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the polyamide 56 industrial yarn, emulsion oiling was used, and the crude oil agent was selected from DELION HQ-618, and the oil agent concentration was adjusted to 15 wt%; other steps were the same as in Example 1.

[0185] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0186] Example 21

[0187] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the polyamide 56 industrial yarn, emulsion oiling was used, and the original oil agent was selected from TCP-60, and the oil agent concentration was adjusted to 15 wt%; other steps were the same as in Example 1.

[0188] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0189] Example 22

[0190] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the high-viscosity polyamide 56 resin, by controlling the polymerization and solid-phase polycondensation processes, the relative viscosity of the prepared high-viscosity polyamide 56 resin in 96% sulfuric acid was 2.8; other steps were the same as in Example 1.

[0191] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0192] Example 23

[0193] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the high-viscosity polyamide 56 resin, by controlling the solid-phase polycondensation process, the moisture content of the prepared high-viscosity polyamide 56 resin was 1000 ppm; other steps were the same as in Example 1.

[0194] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0195] Example 24

[0196] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the polyamide 56 industrial yarn, the total draw ratio of the drawing was 3.5; other steps were the same as in Example 1.

[0197] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0198] Example 25

[0199] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that during the preparation of the polyamide 56 industrial yarn, the temperatures of the fourth, fifth, and sixth pairs of hot rolls were controlled at 150 °C, 130 °C, and 120 °C respectively; other steps were the same as in Example 1.

[0200] The performance index parameters of the polyamide 56 industrial yarn prepared in this example are shown in Table 1.

[0201] Comparative Example 1

[0202] The polyamide 56 industrial yarn was prepared by the same method as in Example 1, except that there was no pre-network device during the preparation of the polyamide 56 industrial yarn; other steps were the same as in Example 1.

[0203] The performance index parameters of the polyamide 56 industrial yarn prepared in this comparative example are shown in Table 1.

[0204]

[0205]

[0206] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A heat-resistant low-hair polyamide 56 industrial yarn, It is characterized in that The content of copper ions in the polyamide 56 industrial yarn is 55-110 ppm; the preparation method of the polyamide 56 industrial yarn comprises: (1) heating a high-viscosity polyamide 56 resin to a molten state to obtain a polyamide 56 melt; (2) conveying the polyamide 56 melt to a spinning manifold through a melt pipe for drawing to form primary yarn; (3) heat-insulating, cooling, oiling, pre-internetting, multi-stage stretching, tension heat setting, two-stage relaxation heat setting, main internetting, and winding the spun yarn to obtain the heat-resistant low-hair polyamide 56 industrial yarn; The content of copper ions in the high-viscosity polyamide 56 resin is 65-130 ppm, and the relative viscosity of 96% sulfuric acid of the high-viscosity polyamide 56 resin is 2.9-4.0; the total stretching multiple of the stretching is 4.5-6.0; the specification of the filter screen in the spinning assembly in the spinning manifold is 300-450 mesh, and the specification of the metal sand in the spinning assembly in the spinning manifold is 40-120 mesh; the oiling is carried out by using crude oil agent.

2. The heat-resistant low-hair polyamide 56 industrial yarn according to claim 1, It is characterized in that The content of copper ions in the polyamide 56 industrial yarn is 60 to 100 ppm; and / or, The polyamide 56 industrial yarn has a heat-resistant breaking strength retention rate of ≥93% after being treated at 170°C for 2 hours; or After the polyamide 56 industrial yarn is treated at 180°C for 4 hours, the heat-resistant breaking strength retention rate is ≥ 92%; or The polyamide 56 industrial yarn has a heat-resistant breaking strength retention rate of ≥85% after being treated at 150°C for 72 hours; or The polyamide 56 industrial yarn has a heat-resistant breaking strength retention rate of ≥65% after being treated at 205°C for 16 hours; or After the polyamide 56 industrial yarn is treated at 230° C. for 30 minutes, the heat-resistant breaking strength retention rate is ≥92%.

3. The heat-resistant low-hair polyamide 56 industrial yarn according to claim 1, It is characterized in that After the polyamide 56 industrial yarn is treated at 170°C for 2 hours, the heat-resistant breaking strength retention rate is ≥95%; or After the polyamide 56 industrial yarn is treated at 180°C for 4 hours, the heat-resistant breaking strength retention rate is ≥93%; or After the polyamide 56 industrial yarn is treated at 150°C for 72 hours, the heat-resistant breaking strength retention rate is ≥88%; or After the polyamide 56 industrial yarn is treated at 205°C for 16 hours, the heat-resistant breaking strength retention rate is ≥ 68%; or After the polyamide 56 industrial yarn is treated at 230° C. for 30 minutes, the heat-resistant breaking strength retention rate is ≥94%.

4. The heat-resistant low-hair polyamide 56 industrial yarn according to claim 1, It is characterized in that After the polyamide 56 industrial yarn is treated at 170°C for 2h, the heat-resistant breaking strength retention rate is ≥97%; or After the polyamide 56 industrial yarn is treated at 180°C for 4 hours, the heat-resistant breaking strength retention rate is ≥94%; or After the polyamide 56 industrial yarn is treated at 150 °C for 72 h, the heat-resistant breaking strength retention rate is ≥ 90%; or, After the polyamide 56 industrial yarn is treated at 205 °C for 16 h, the heat-resistant breaking strength retention rate is ≥ 70%; or, After the polyamide 56 industrial yarn is treated at 230 °C for 30 min, the heat-resistant breaking strength retention rate is ≥ 95%.

5. The heat-resistant low-hairiness polyamide 56 industrial yarn according to claim 1, wherein the content of copper ions in the polyamide 56 industrial yarn is 65-80 ppm; and / or, the breaking strength of the polyamide 56 industrial yarn is 6.0-9.5 cN / dtex; and / or, the breaking elongation of the polyamide 56 industrial yarn is 8-26%; and / or, the evenness variation coefficient of the polyamide 56 industrial yarn is ≤ 1.5%; and / or, the fineness of the polyamide 56 industrial yarn is 120-3000 dtex; and / or, the number of holes of the polyamide 56 industrial yarn is 18-288 f; and / or, the initial modulus of the polyamide 56 industrial yarn is 40-65 cN / dtex; and / or, the dry heat shrinkage rate of the polyamide 56 industrial yarn is ≤ 6.0%; and / or, the boiling water shrinkage rate of the polyamide 56 industrial yarn is ≤ 9.0%.

6. The heat-resistant low-hairiness polyamide 56 industrial yarn according to claim 1, wherein the breaking strength of the polyamide 56 industrial yarn is 6.5-9.2 cN / dtex; and / or, the breaking elongation of the polyamide 56 industrial yarn is 12-24%; and / or, the evenness variation coefficient of the polyamide 56 industrial yarn is ≤ 1.3%; and / or, the fineness of the polyamide 56 industrial yarn is 150-2600 dtex; and / or, the number of holes of the polyamide 56 industrial yarn is 24-140 f; and / or, the initial modulus of the polyamide 56 industrial yarn is 44-60 cN / dtex; and / or, the dry heat shrinkage rate of the polyamide 56 industrial yarn is ≤ 5.5%; and / or, the boiling water shrinkage rate of the polyamide 56 industrial yarn is ≤ 8.0%.

7. The heat-resistant low-hairiness polyamide 56 industrial yarn according to claim 1, wherein the breaking strength of the polyamide 56 industrial yarn is 7.0-8.8 cN / dtex; and / or, the breaking elongation of the polyamide 56 industrial yarn is 14-22%; and / or, the evenness variation coefficient of the polyamide 56 industrial yarn is ≤ 1.1%; and / or, the fineness of the polyamide 56 industrial yarn is 200-2000 dtex; and / or, the number of holes of the polyamide 56 industrial yarn is 36-105 f; and / or, the initial modulus of the polyamide 56 industrial yarn is 48-55 cN / dtex; and / or, the dry heat shrinkage rate of the polyamide 56 industrial yarn is ≤ 5.0%; and / or, the boiling water shrinkage rate of the polyamide 56 industrial yarn is ≤ 7.0%.

8. The heat-resistant low-hairiness polyamide 56 industrial yarn according to claim 1, wherein the number of holes of the polyamide 56 industrial yarn is 48-86 f; and / or, The component replacement cycle of the polyamide 56 industrial yarn is ≥25 days; and / or, The number of single broken filaments of the polyamide 56 industrial yarn is ≤2 times / 1 spinning position / 24 h; and / or, The yield rate of the polyamide 56 industrial yarn is ≥96%; and / or, The hairiness of the polyamide 56 industrial yarn is ≤2 per 10 kg cake.

9. The heat-resistant low-hairiness polyamide 56 industrial yarn according to claim 1, characterized in that the component replacement cycle of the polyamide 56 industrial yarn is ≥28 days; and / or, the number of single broken filaments of the polyamide 56 industrial yarn is ≤1 time / 1 spinning position / 24 h; and / or, the yield rate of the polyamide 56 industrial yarn is ≥97%; and / or, the hairiness of the polyamide 56 industrial yarn is ≤1 per 10 kg cake.

10. The heat-resistant low-hairiness polyamide 56 industrial yarn according to claim 1, characterized in that the component replacement cycle of the polyamide 56 industrial yarn is ≥30 days; and / or, the number of single broken filaments of the polyamide 56 industrial yarn is ≤0 times / 1 spinning position / 24 h; and / or, the yield rate of the polyamide 56 industrial yarn is ≥98%; and / or, the hairiness of the polyamide 56 industrial yarn is ≤0 per 10 kg cake.

11. A method for preparing the heat-resistant low-hairiness polyamide 56 industrial yarn according to any one of claims 1 to 10, characterized in that the method comprises: (1) Heating the high-viscosity polyamide 56 resin to a molten state to obtain a polyamide 56 melt; (2) Transporting the polyamide 56 melt through a melt pipeline to a spinning box for drawing to form a nascent yarn; (3) Performing heat preservation, cooling, oiling, pre-networking, multi-stage drawing, tension heat setting, two-stage relaxation heat setting, main networking, and winding on the nascent yarn to obtain the heat-resistant low-hairiness polyamide 56 industrial yarn; the content of copper ions in the high-viscosity polyamide 56 resin is 65 - 130 ppm, the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid is 2.9 - 4.0; the total draw ratio of the drawing is 4.5 - 6.0; the specification of the filter screen in the spinning component in the spinning box is 300 - 450 meshes, and the specification of the metal sand in the spinning component in the spinning box is 40 - 120 meshes; the oiling is performed by using crude oil agent for oiling.

12. The method according to claim 11, characterized in that in step (1), the content of copper ions in the high-viscosity polyamide 56 resin is 65 - 110 ppm; and / or, the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid is 3.1 - 3.8; and / or, the moisture content of the high-viscosity polyamide 56 resin is 280 - 530 ppm.

13. The method according to claim 11, characterized in that in step (1), the content of copper ions in the high-viscosity polyamide 56 resin is 70 - 90 ppm; and / or, the relative viscosity of the high-viscosity polyamide 56 resin in 96% sulfuric acid is 3.3 - 3.6; and / or, the moisture content of the high-viscosity polyamide 56 resin is 320 - 500 ppm; and / or, In step (1), the high-viscosity polyamide 56 resin contains a heat stabilizer selected from one or more of copper acetate, cuprous iodide, potassium iodide, and potassium bromide.

14. According to the method described in claim 13, characterized in that the heat stabilizer is added during the polymerization process or injected online in the form of a heat-resistant masterbatch before pelletizing the polymerization melt; and / or, the moisture content of the high-viscosity polyamide 56 resin is 350 - 450 ppm; and / or, the heat stabilizer is a compound of copper acetate with potassium iodide and / or potassium bromide, or a compound of cuprous iodide with potassium iodide and / or potassium bromide.

15. According to the method described in claim 11, characterized in that the heating in step (1) is carried out in a screw extruder, and the screw extruder is divided into five zones for heating; among them, the temperature of the first zone is 260 - 290 °C, the temperature of the second zone is 270 - 300 °C, the temperature of the third zone is 280 - 310 °C, the temperature of the fourth zone is 290 - 310 °C, and the temperature of the fifth zone is 280 - 300 °C; and / or, the drawing in step (2) is to extrude the polyamide 56 melt through the spinneret of the spinning box to form the nascent filament; and / or, the temperature of the spinning box is 282 - 294 °C; and / or, the pressure of the spinning component in the spinning box is 10 - 20 MPa; and / or, the retention rate of copper ions in the polyamide 56 industrial yarn is ≥ 82%.

16. According to the method described in claim 15, characterized in that the temperature of the spinning box is 284 - 292 °C; and / or, the pressure of the spinning component in the spinning box is 12 - 18 MPa; and / or, the specification of the metal sand in the spinning component is 45 - 100 mesh; and / or, the retention rate of copper ions in the polyamide 56 industrial yarn is ≥ 85%.

17. According to the method described in claim 15, characterized in that the temperature of the spinning box is 286 - 290 °C; and / or, the pressure of the spinning component in the spinning box is 13 - 16 MPa; and / or, the specification of the metal sand in the spinning component is 60 - 80 mesh; and / or, the retention rate of copper ions in the polyamide 56 industrial yarn is ≥ 90%.

18. According to the method described in claim 11, characterized in that the heat preservation in step (3) is carried out by a slow cooling device, the slow cooling height is 240 - 320 mm; the slow cooling temperature is 260 - 320 °C; and / or, the cooling is carried out by side blowing, the wind speed is 0.5 - 0.8 m / s, and the wind temperature is 16 - 22 °C; and / or, The oiling rate of the oiling is 0.9 to 1.2 wt%, and the dynamic viscosity of the crude oil agent is ≤ 150 mm 2 / s. The crude oil agent is selected from at least one of DELION F-8740-N, HQ-68-H, DELION HQ-635, Lupert TM A275, N-350, N-353, LIMANOL TL8E, NEO TEX-903(A), D-3088, dakao Neat crude oil type agent, TCP-80 polyamide industrial yarn / cord oil agent, TC1152, TC1355, and TC-14686; and / or, the pressure of the pre-network is 1 - 2.5 bar; and / or, The stretching process is carried out using 5 or more pairs of hot rollers and is divided into five levels of stretching. The stretching process is as follows: The as-spun filament after oiling is first fed into the first pair of hot rollers, and the first-stage pre-stretching is carried out between the first pair of hot rollers and the second pair of hot rollers. Then, the second-stage main stretching is carried out between the second pair of hot rollers and the third pair of hot rollers. The third-stage main stretching and tension heat setting are carried out between the third pair of hot rollers and the fourth pair of hot rollers. The fourth-stage sub-stretching and the first relaxation heat setting are carried out between the fourth pair of hot rollers and the fifth pair of hot rollers. Then, the fifth-stage sub-stretching and the second relaxation heat setting are carried out between the fifth pair of hot rollers and the sixth pair of hot rollers; Among them, the speed of the first pair of hot rollers is 400 - 800 m / min, and the temperature is 20 - 70 °C; and / or, the speed of the second pair of hot rollers is 450 - 950 m / min, and the temperature is 80 - 150 °C; and / or, the speed of the third pair of hot rollers is 1500 - 2500 m / min, and the temperature is 100 - 190 °C; and / or, the speed of the fourth pair of hot rollers is 2400 - 3200 m / min, and the temperature is 180 - 230 °C; and / or, the speed of the fifth pair of hot rollers is 2300 - 3100 m / min, and the temperature is 160 - 220 °C; and / or, the speed of the sixth pair of hot rollers is 2200 - 3000 m / min, and the temperature is 140 - 210 °C; and / or, The stretching multiple of the first-stage pre-stretching is 1.0 - 1.2; and / or, the stretching multiple of the second-stage main stretching is 3.0 - 4.0; and / or, the stretching multiple of the third-stage main stretching is 1.3 - 1.6; and / or, the stretching multiple of the fourth-stage sub-stretching is 0.9 - 1.0; and / or, the stretching multiple of the fifth-stage sub-stretching is 0.9 - 1.0; and / or, the total stretching multiple of the stretching is 4.8 - 5.5; and / or, The main network pressure is 2.5 - 4.5 bar; and / or, The winding speed is 2200 - 3000 m / min; and / or, The overfeed ratio of the winding is 0.8 - 5%.

19. According to the method described in claim 18, characterized in that, The slow cooling height is 260 - 300 mm; and / or, The slow cooling temperature is 280 - 310 °C; and / or, The wind speed is 0.6 - 0.7 m / s; and / or, The wind temperature is 18 - 20 °C; and / or, The dynamic viscosity of the crude oil agent is ≤ 120 mm 2 / s; and / or, The crude oil agent is selected from at least one of DELION F-8740-N, HQ-68-H, DELION HQ-635, N-353, TC1355 and Lupert TM ; and / or, The pressure of the pre-network is 1.5 - 2.0 bar; and / or, The stretching process is carried out using 6 pairs of hot rollers; and / or, The stretching multiple of the first-stage pre-stretching is 1.05 - 1.15; and / or, The stretching multiple of the second-stage main stretching is 3.2 - 3.8; and / or, The stretching multiple of the third-stage main stretching is 1.35 - 1.5; and / or, The stretching multiple of the fourth-stage sub-stretching is 0.94 - 0.98; and / or, the stretching multiple of the fifth-stage sub-stretching is 0.92 - 0.95; and / or, The main network pressure is 3.0 - 3.5 bar; and / or, The winding speed is 2,400 to 2,800 m / min; and / or, The overfeed ratio of the winding is 1% to 4%.

20. According to the method described in claim 18, It is characterized in that The dynamic viscosity of the crude oil agent is ≤ 90 mm 2 / s; and / or, The speed of the first pair of hot rolls is 450 to 750 m / min; and / or, The temperature of the first pair of hot rolls is 30 to 60 °C; and / or, The speed of the second pair of hot rolls is 500 to 900 m / min; and / or, The temperature of the second pair of hot rolls is 100 to 130 °C; and / or, The speed of the third pair of hot rolls is 1,700 to 2,300 m / min; and / or, The temperature of the third pair of hot rolls is 130 to 180 °C; and / or, The speed of the fourth pair of hot rolls is 2,500 to 3,100 m / min; and / or, The temperature of the fourth pair of hot rolls is 190 to 220 °C; and / or, The speed of the fifth pair of hot rolls is 2,400 to 3,000 m / min; and / or, The temperature of the fifth pair of hot rolls is 170 to 200 °C; and / or, The speed of the sixth pair of hot rolls is 2,300 to 2,900 m / min; and / or, The temperature of the sixth pair of hot rolls is 150 to 180 °C; and / or, The winding speed is 2,500 to 2,600 m / min; and / or, The overfeed ratio of the winding is 1.5% to 3%.

21. An application of the heat-resistant low-hairiness polyamide 56 industrial yarn according to any one of claims 1 to 10 in the fields of tire cord, airbag yarn, release cloth, sewing thread, water cloth, canvas, seat belt, rope, fishing net, industrial filter cloth, conveyor belt, parachute, tent or luggage.

Images