阅读说明：本技术 一种高粘聚酰胺56树脂、高强聚酰胺56工业丝及其制备方法与应用 (High-viscosity polyamide 56 resin, high-strength polyamide 56 industrial yarn and preparation method and application thereof ) 是由 孙朝续 陈万钟 刘修才 于 2020-03-31 设计创作，主要内容包括：本发明提供了一种高粘聚酰胺56树脂、高强聚酰胺56工业丝及其制备方法与应用。所述高强聚酰胺56工业丝的制备方法为将高粘聚酰胺56树脂采用单螺杆或双螺杆挤出机加热熔融,进入纺丝箱进行拉丝得到初生丝,然后对初生丝进行保温、冷却、上油、预网络、多级拉伸、紧张定型、松弛定型、主网络、卷绕制得。本发明提供的高强聚酰胺56工业丝具有较好的力学性能与耐湿热性能,可应用于缝纫线、轮胎帘子线、气囊丝、脱模布、水布、帆布、安全带、绳索、渔网、工业过滤布、传输带、降落伞、帐篷、箱包领域。(The invention provides a high-viscosity polyamide 56 resin, a high-strength polyamide 56 industrial yarn, and a preparation method and application thereof. The preparation method of the high-strength polyamide 56 industrial yarn comprises the steps of heating and melting high-viscosity polyamide 56 resin by a single-screw or double-screw extruder, drawing the molten resin in a spinning box to obtain a primary yarn, and then carrying out heat preservation, cooling, oiling, pre-networking, multi-stage drawing, tension sizing, relaxation sizing, main networking and winding on the primary yarn to obtain the high-strength polyamide 56 industrial yarn. The high-strength polyamide 56 industrial yarn provided by the invention has better mechanical property and damp-heat resistance, and can be applied to the fields of sewing threads, tire cord threads, air bag yarns, demolding cloth, water cloth, canvas, safety belts, ropes, fishing nets, industrial filter cloth, transmission belts, parachutes, tents and bags.)

1. A high viscosity polyamide 56 resin characterized by: the relative viscosity of the high-viscosity polyamide 56 resin 96% sulfuric acid is 3.2-3.8, preferably 3.3-3.6, and more preferably 3.4-3.5; and/or the presence of a gas in the gas,

the water content of the high-viscosity polyamide 56 resin after the resin humidity conditioning treatment is 300-600 ppm, preferably 350-550 ppm, and more preferably 400-500 ppm.

2. The high viscosity polyamide 56 resin of claim 1, wherein: the number average molecular weight of the high-viscosity polyamide 56 resin is 25000-50000, preferably 30000-45000, and more preferably 35000-40000; and/or the presence of a gas in the gas,

the molecular weight distribution of the high-viscosity polyamide 56 resin is 1.5-2.2, preferably 1.7-2.1, and more preferably 1.8-2.0; and/or the presence of a gas in the gas,

the oligomer content of the high-viscosity polyamide 56 resin is less than or equal to 1.0 wt%, preferably less than or equal to 0.8 wt%, and more preferably less than or equal to 0.6 wt%; and/or the presence of a gas in the gas,

the thermal crystallization peak temperature of the high-viscosity polyamide 56 resin is more than or equal to 208 ℃, preferably more than or equal to 212 ℃, and more preferably more than or equal to 215 ℃; and/or the presence of a gas in the gas,

the width of the thermal crystallization peak half width of the high-viscosity polyamide 56 resin is less than or equal to 10 ℃, preferably less than or equal to 8 ℃, and more preferably less than or equal to 6 ℃; and/or the presence of a gas in the gas,

the oligomer of the high viscosity polyamide 56 resin includes one or more of a cyclic mono-, cyclic dimer, and cyclic trimer of adipic acid and pentanediamine.

3. A method for producing the highly viscous polyamide 56 resin according to claim 1 or 2, characterized in that: the method comprises the following steps:

(1) drying low-viscosity polyamide 56 resin with the relative viscosity of 2.4-2.8 at high temperature to obtain tackifying polyamide 56 resin;

(2) and (2) subjecting the tackifying polyamide 56 resin obtained in the step (1) to resin humidity conditioning treatment to obtain the high-viscosity polyamide 56 resin.

4. The method of claim 3, wherein: in the step (1), the step (c),

the high-temperature drying treatment adopts vacuum pumping or inert gas protection, and the vacuum degree during the vacuum pumping is-0.05 to-0.1 Mpa; and/or the presence of a gas in the gas,

the temperature of the high-temperature drying treatment is 150-200 ℃, and preferably 160-180 ℃; and/or the presence of a gas in the gas,

the time of the high-temperature drying treatment is 10-30 hours, preferably 15-25 hours; and/or the presence of a gas in the gas,

the equipment for high-temperature drying treatment is a vacuum drum dryer or a continuous dehumidifying hot nitrogen dryer; and/or the presence of a gas in the gas,

the relative viscosity of the tackifying polyamide 56 resin is 3.2-3.8, and the water content is 30-200 ppm.

5. The method of claim 3, wherein: in the step (2),

the moisture content of the high-viscosity polyamide 56 resin subjected to resin moisture conditioning treatment is 300-600 ppm; and/or the presence of a gas in the gas,

the temperature of the resin humidity adjustment treatment is 80-110 ℃; and/or the presence of a gas in the gas,

the resin humidity adjustment treatment is carried out by mixing nitrogen with water vapor, and the dew point of the nitrogen is controlled within the range of-20 ℃ to 20 ℃.

6. A high-strength polyamide 56 industrial yarn is characterized in that: the breaking strength of the high-strength polyamide 56 industrial yarn is 8.0-10.0 cN/dtex, preferably 8.3-9.5 cN/dtex, and more preferably 8.6-9.3 cN/dtex; and/or the presence of a gas in the gas,

after the water bath treatment, the breaking strength retention rate of the high-strength polyamide 56 industrial yarn is more than or equal to 88%, preferably more than or equal to 90%, and more preferably more than or equal to 92%; and/or the presence of a gas in the gas,

after the industrial yarn moisture-conditioning treatment, the breaking strength retention rate of the high-strength polyamide 56 industrial yarn is not less than 90%, preferably not less than 93%, and more preferably not less than 95%.

7. The high tenacity polyamide 56 industrial yarn of claim 6, wherein: the breaking elongation of the high-strength polyamide 56 industrial yarn is 16-24%, preferably 18-22%, and more preferably 19-20%; and/or the presence of a gas in the gas,

after the water bath treatment, the breaking elongation of the high-strength polyamide 56 industrial yarn is less than or equal to 33 percent, preferably less than or equal to 28 percent, and more preferably less than or equal to 25 percent; the elongation fluctuation is less than or equal to 10 percent, preferably less than or equal to 8 percent, and more preferably less than or equal to 6 percent; and/or the presence of a gas in the gas,

after the industrial yarn is subjected to humidity adjustment treatment, the breaking elongation of the high-strength polyamide 56 industrial yarn is less than or equal to 27%, preferably less than or equal to 26%, and more preferably less than or equal to 25%; the elongation fluctuation is 3% or less, preferably 2% or less, more preferably 1% or less.

8. The high tenacity polyamide 56 industrial yarn of claim 6, wherein: the water bath treatment temperature is 70-110 ℃, the preferable temperature is 75-100 ℃, the more preferable temperature is 80-90 ℃, and the water bath treatment time is 20-60 min, the preferable time is 30-50 min; and/or the humidity adjusting temperature is 18-30 ℃, preferably 20-27 ℃, the humidity adjusting humidity is 60-95%, and the humidity adjusting time is 1-48 h, preferably 4-40 h, and more preferably 8-30 h; and/or the presence of a gas in the gas,

the filament breakage frequency of the high-strength polyamide 56 industrial filament is less than or equal to 5 per 24h, preferably less than or equal to 3 per 24h, and more preferably less than or equal to 2 per 24 h; and/or the presence of a gas in the gas,

the broken filaments of the high-strength polyamide 56 industrial yarn are less than or equal to 10/10 kg packages, preferably less than or equal to 8/10 kg packages, and more preferably less than or equal to 5/10 kg packages.

9. A method for preparing the high strength polyamide 56 industrial yarn as claimed in any one of claims 6 to 8, characterized in that: the preparation method comprises the following steps:

(1) heating the high-viscosity polyamide 56 resin to a molten state to prepare a polyamide 56 melt;

(2) conveying the polyamide 56 melt prepared in the step (1) to a spinning manifold through a melt pipeline for drawing to prepare a primary yarn;

(3) and (3) carrying out heat preservation, cooling, oiling, pre-networking, multi-stage stretching, tension sizing, relaxation sizing, main networking and winding on the primary yarn prepared in the step (2) to obtain the high-strength polyamide 56 industrial yarn.

10. The method for preparing high-strength polyamide 56 industrial yarn according to claim 9, characterized in that: the relative viscosity of the high-viscosity polyamide 56 resin 96% sulfuric acid in the step (1) is 3.3-4.0, preferably 3.4-3.8, and more preferably 3.5-3.6; and/or the presence of a gas in the gas,

the water content of the high-viscosity polyamide 56 resin is 300-550 ppm, preferably 350-500 ppm, and more preferably 400-450 ppm.

11. The method for preparing high-strength polyamide 56 industrial yarn according to claim 9, characterized in that: in the step (2), the drawing is to spray the polyamide 56 melt through a spinneret plate of a spinning manifold to form the primary yarn; and/or the presence of a gas in the gas,

the temperature of the spinning manifold is 280-295 ℃, preferably 283-293 ℃, and more preferably 285-290 ℃; and/or the presence of a gas in the gas,

the pressure of a spinning assembly of the spinning manifold is 13-25 MPa, preferably 15-20 MPa, and more preferably 17-18 MPa.

12. The method for preparing high-strength polyamide 56 industrial yarn according to claim 9, characterized in that: in the step (3), the heat preservation adopts a slow cooling device, the slow cooling device is a hot jacket which is arranged at the lower part of the spinneret plate and is closely adjacent to the spinneret plate, the slow cooling height refers to the thickness of the hot jacket, and the slow cooling height is 100-350 mm, preferably 200-300 mm; the slow cooling temperature refers to the ambient temperature around the tows, and is 250-320 ℃, preferably 270-300 ℃; and/or the presence of a gas in the gas,

the cooling is air cooling by cross air blowing or circular air blowing, and the air cooling speed is 0.4-0.9 m/s, preferably 0.6-0.8 m/s; the air temperature of the air cooling is 16-25 ℃, and preferably 18-22 ℃; the air-cooled air humidity is 60-90%, and preferably 75-85%; and/or the presence of a gas in the gas,

the concentration of the oiling agent used in oiling is 8-100 wt%, and preferably 65-100 wt%, the dynamic viscosity of the oiling agent is less than or equal to 300mPas, preferably less than or equal to 200mPas, and more preferably less than or equal to 100 mPas; and/or the presence of a gas in the gas,

the oiling comprises the mode of oiling by adopting an oil nozzle, an oil tanker or an oil lip, for example, 2 or more oil nozzles, oil tankers or oil lips are adopted for oiling, and 2 oil nozzles are preferably adopted for oiling; and/or the height of the oil nozzle from the spinneret plate is more than or equal to 3m, preferably more than or equal to 3.5m, and more preferably more than or equal to 4 m; and/or the width of the oil nozzle is 8-25 mm, preferably 10-22 mm, and more preferably 12-18 mm; and/or the oiling rate is 0.6-2.0%, preferably 0.8-1.5%, and more preferably 1.0-1.2%; and/or the presence of a gas in the gas,

the pre-network pressure is 1-2.5 bar, preferably 1.5-2.0 bar; and/or the presence of a gas in the gas,

the stretching process adopts 5 pairs of hot rollers and is divided into four stages of stretching, and the stretching process comprises the following steps: feeding oiled nascent yarn to a first pair of hot rollers, performing primary pre-stretching between the first pair of hot rollers and a second pair of hot rollers, performing secondary main stretching between the second pair of hot rollers and a third pair of hot rollers, performing tertiary main stretching between the third pair of hot rollers and a fourth pair of hot rollers and performing tension heat setting, and performing fourth-stage secondary stretching between the fourth pair of hot rollers and a fifth pair of hot rollers and performing relaxation heat setting;

among them, preferred are: the stretching ratio of the first-stage stretching is 1.0-1.1; and/or the stretching multiple of the second-stage stretching is 3.0-4.0; and/or the stretching multiple of the third stage stretching is 1.3-1.6; and/or the stretching multiple of the fourth stage stretching is 0.9-1.0; and/or the total stretching multiple of the stretching is preferably 4.5-6.0;

and/or the temperature of the tension heat setting is 180-230 ℃, preferably 200-220 ℃; and/or the temperature of the relaxation heat setting is 120-200 ℃, preferably 140-180 ℃; and/or the speed retraction of the fourth heat roller pair and the fifth heat roller pair is 50-200 m/min, preferably 100-150 m/min;

and/or the main network pressure is 2.5-4.5 bar, preferably 3.0-3.5 bar;

and/or the winding speed is 2200 to 3300m/min, preferably 2500 to 3000m/min, and more preferably 2600 to 2800 m/min.

13. Use of the high tenacity polyamide 56 industrial yarn of any one of claims 6 to 8 in sewing thread, tire cord, air bag yarn, release fabric, tarpaulin, canvas, safety belts, ropes, fishing nets, industrial filter cloth, conveyor belts, parachutes, tents, bags and suitcases.

Technical Field

The invention belongs to the technical field of polyamide materials, and relates to high-viscosity polyamide 56 resin, a high-strength polyamide 56 industrial yarn, and a preparation method and application thereof.

Background

The terylene and chinlon industrial yarns have the characteristics of high strength, low elongation, good dimensional stability, fatigue resistance, aging resistance and the like, so that the terylene and chinlon industrial yarns are widely applied to the fields of tire cords, canvases, transmission belts, safety airbags, parachutes, ropes, safety belts, industrial filter cloth or tents and the like.

The production process of the industrial yarn has two types: one adopts a melt direct spinning method, and the other adopts a sliced solid-phase tackifying indirect spinning method. The polyamide 66 and the polyethylene glycol terephthalate are partially directly spun by melt, and the polyamide 6 contains 8-10 wt% of monomers, so that the monomers need to be removed in a single procedure, the melt spinning cannot be directly carried out at present, low-viscosity resin needs to be prepared, and then the high-viscosity slice is prepared by solid-phase tackifying to produce the industrial yarn.

At present, no relevant research report exists on the polyamide 56 solid-phase tackifying technology and the application of the polyamide 56 solid-phase tackifying technology in industrial yarns, and particularly no relevant research exists on the humidifying treatment of the resin after solid-phase tackifying and the adoption of the twin-screw online water-jet spinning technology.

The patent number CN 106868624B discloses a polyamide 5X high-strength yarn and a preparation method thereof, wherein the breaking strength of the polyamide 5X high-strength yarn is 8.0-10.0 cN/dtex, the breaking elongation is 10-15%, and the breaking elongation of the polyamide 5X high-strength yarn is low. The patent number CN 106835329B discloses a polyamide 5X medium-strength yarn and a preparation method thereof, wherein the breaking strength of the polyamide 5X medium-strength yarn is 6.0-8.0 cN/dtex, the breaking elongation is 20.8-25%, and the breaking strength of the polyamide 5X medium-strength yarn is low. The patent CN 110055602A discloses a polyamide 56 high-tenacity industrial yarn and a preparation method thereof, wherein a high-speed winding low-power drafting process is adopted, the winding speed is more than 4000m/min, and the total drafting multiplying factor is 1.90-2.85. The high-strength industrial yarn is prepared by a high-power drafting and low-speed winding process, the drafting multiple is more than or equal to 4.0 times, and the winding speed is less than or equal to 3500 m/min. The high-speed winding low-power drawing process is adopted, the winding speed is higher than 4000m/min, the drawing multiple is smaller than 3.0, the winding speed is high, the retention time on different hot rollers in the fiber drawing process is relatively shortened, namely the high-temperature setting time of the fiber is shortened, and then the low-power drawing process is adopted, so that the fiber crystallization and orientation are relatively low, and the breaking strength and the dimensional stability of the prepared fiber are relatively low.

On the other hand, polyamide 56 has an odd-even carbon arrangement structure, the proportion of amido bonds is high, the water absorption is strong, the saturated water absorption is about 50% higher than that of polyamide 66 and about 30% higher than that of PA6, and in the spinning process, in order to eliminate fiber static electricity and reduce equipment friction damage, the nascent filaments exiting from a spinneret orifice need to be oiled. At present, polyester, polyamide 6 and polyamide 66 industrial yarns generally adopt an emulsion oil tanker oiling mode, the moisture content in emulsion is 80-90%, polyamide 56 adopts emulsion oiling, nascent yarns in the oiling process can quickly absorb moisture in the emulsion to cause a water absorption crystallization phenomenon, the fiber crystallinity is increased, the subsequent high-power drafting of the fibers is not facilitated, the fiber breaking strength is reduced, the subsequent high-power drafting is carried out, the monofilament breaking frequency and the yarn cake broken yarn number can be increased, and the normal production cannot be realized. Therefore, the development of high-strength polyamide 56 industrial yarn with good mechanical properties and resistance to moist heat is a technical problem to be solved urgently at present.

Disclosure of Invention

The first purpose of the invention is to provide a high-viscosity polyamide 56 resin and a preparation method thereof.

The tackifying polyamide 56 resin is prepared by controlling the drying temperature, time, vacuum degree or nitrogen flow rate, the amino and carboxyl of the low-viscosity polyamide 56 resin continue to perform polycondensation reaction under the conditions of high temperature, vacuum or nitrogen atmosphere, the water produced by the reaction is continuously pumped away, the chemical forward reaction is promoted, the tackifying polyamide 56 resin is obtained, meanwhile, the water content of the resin is reduced, the viscosity is too high, the melt flowability is reduced, the subsequent high-power drafting of the industrial yarn is influenced, the polyamide 56 resin with proper water content and high viscosity is prepared again by adding a resin humidifying treatment link, and the melt flowability is improved.

Through the optimization of the drying process, the obtained high-viscosity polyamide 56 resin has the advantages of large molecular weight, narrow molecular weight distribution, low micromolecule content, increased thermal crystallization temperature and small width of half peak width of a crystallization peak.

The second purpose of the invention is to provide the high-strength humidity-heat-resistant polyamide 56 industrial yarn and the preparation method thereof.

The third purpose of the invention is to provide the application of the high-strength polyamide 56 industrial yarn.

In order to achieve the above purpose, the solution of the invention is as follows:

the invention provides a high-viscosity polyamide 56 resin, wherein the relative viscosity of 96% sulfuric acid of the high-viscosity polyamide 56 resin is 3.2-3.8, preferably 3.3-3.6, and more preferably 3.4-3.5; and/or the presence of a gas in the gas,

the water content of the high-viscosity polyamide 56 resin after the resin humidity conditioning treatment is 300-600 ppm, preferably 350-550 ppm, and more preferably 400-500 ppm.

Preferably, the number average molecular weight of the high-viscosity polyamide 56 resin is 25000-50000, preferably 30000-45000, and more preferably 35000-40000; and/or the presence of a gas in the gas,

the number average molecular weight distribution of the high-viscosity polyamide 56 resin is 1.5-2.2, preferably 1.7-2.1, and more preferably 1.8-2.0; and/or the presence of a gas in the gas,

the oligomer content of the high-viscosity polyamide 56 resin is less than or equal to 1.0 wt%, preferably less than or equal to 0.8 wt%, and more preferably less than or equal to 0.6 wt%; and/or the presence of a gas in the gas,

the thermal crystallization peak temperature of the high-viscosity polyamide 56 resin is more than or equal to 208 ℃, preferably more than or equal to 212 ℃, and more preferably more than or equal to 215 ℃, and the half-peak width of the thermal crystallization peak of the high-viscosity polyamide 56 resin is less than or equal to 10 ℃, preferably less than or equal to 8 ℃, and more preferably less than or equal to 6 ℃; and/or the presence of a gas in the gas,

the oligomer of the high viscosity polyamide 56 resin includes one or more of a cyclic mono-, cyclic dimer, and cyclic trimer of adipic acid and pentanediamine.

The raw materials for producing the high-strength polyamide 56 resin comprise 1, 5-pentanediamine and adipic acid; alternatively, the polyamide resin 56 may be obtained by polymerizing 1, 5-pentanediamine and adipic acid as monomers, wherein the pentanediamine may be chemically or biologically derived 1, 5-pentanediamine, and preferably is biologically derived 1, 5-pentanediamine.

In another aspect of the present invention, there is also provided a method for preparing a highly viscous polyamide 56 resin, comprising the steps of:

(1) drying low-viscosity polyamide 56 resin with the relative viscosity of 2.4-2.8 at high temperature to obtain tackifying polyamide 56 resin; (2) and (2) subjecting the tackifying polyamide 56 resin obtained in the step (1) to resin humidity conditioning treatment to obtain the high-viscosity polyamide 56 resin.

In some preferred embodiments of the present invention, in step (1), the high-temperature drying treatment is performed by vacuum pumping or inert gas shielding, and the vacuum degree during the vacuum pumping is-0.05 to-0.1 Mpa; and/or the temperature of the high-temperature drying treatment is 150-200 ℃, and preferably 160-180 ℃; and/or the time of the high-temperature drying treatment is 10-30 hours, preferably 15-25 hours; and/or the equipment for high-temperature drying treatment is a vacuum drum dryer or a continuous dehumidifying hot nitrogen dryer; and/or the tackifying polyamide 56 resin has a relative viscosity of 3.2-3.8 and a water content of 30-200 ppm.

In some preferred embodiments of the present invention, in the step (2), the moisture content of the high-viscosity polyamide 56 resin after the resin humidity conditioning treatment is 300 to 600 ppm; and/or the temperature of the resin humidity conditioning treatment is 80-110 ℃; and/or the resin humidity adjustment treatment is carried out by adopting nitrogen mixed with water vapor, and the dew point of the nitrogen is controlled within the range of-20 ℃ to 20 ℃.

The invention also provides a high-strength polyamide 56 industrial yarn, wherein the breaking strength of the high-strength polyamide 56 industrial yarn is 8.0-10.0 cN/dtex, preferably 8.3-9.5 cN/dtex, and more preferably 8.6-9.3 cN/dtex; and/or after water bath treatment, the breaking strength retention rate of the high-strength polyamide 56 industrial yarn is more than or equal to 88%, preferably more than or equal to 90%, and more preferably more than or equal to 92%; and/or after the industrial yarn is subjected to humidity conditioning treatment, the breaking strength retention rate of the high-strength polyamide 56 industrial yarn is not less than 90%, preferably not less than 93%, and more preferably not less than 95%.

Preferably, the breaking elongation of the high-strength polyamide 56 industrial yarn is 16-24%, preferably 17-22%, and more preferably 18-20%; and/or after the water bath treatment, the breaking elongation of the high-strength polyamide 56 industrial yarn is less than or equal to 33 percent, preferably less than or equal to 28 percent, and more preferably less than or equal to 25 percent; and/or the elongation fluctuation is less than or equal to 10%, preferably less than or equal to 8%, more preferably less than or equal to 6%; and/or after the industrial yarn is subjected to humidity conditioning treatment, the breaking elongation of the high-strength polyamide 56 industrial yarn is less than or equal to 27%, preferably less than or equal to 26%, and more preferably less than or equal to 25%; the elongation fluctuation is 3% or less, preferably 2% or less, more preferably 1% or less.

In some preferred embodiments of the present invention, the water bath treatment temperature is 70 to 110 ℃, preferably 75 to 100 ℃, more preferably 80 to 90 ℃, and the water bath treatment time is 20 to 60min, preferably 30 to 50 min; and/or the humidity adjusting temperature is 18-30 ℃, preferably 20-27 ℃, the humidity adjusting humidity is 60-95%, and the humidity adjusting time is 1-48 h, preferably 4-40 h, and more preferably 8-30 h.

In some preferred embodiments of the present invention, the water bath treatment temperature as described above is 90 ℃ for 30 min.

In some preferred embodiments of the present invention, the industrial yarn conditioning treatment temperature is 20 ℃, the relative humidity is 65.0%, and the time is 24 hours.

In some preferred embodiments of the invention, the number of times of filament breakage of the high-strength polyamide 56 industrial filament is less than or equal to 5 per 24h, preferably less than or equal to 3 per 24h, and more preferably less than or equal to 2 per 24 h; and/or the broken filaments of the high-strength polyamide 56 industrial filaments are less than or equal to 10 filaments/10 kg packages, preferably less than or equal to 8 filaments/10 kg packages, and more preferably less than or equal to 5 filaments/10 kg packages.

On the other hand, the invention also provides a preparation method of the high-strength polyamide 56 industrial yarn, which comprises the following steps:

(1) heating the high-viscosity polyamide 56 resin to a molten state to prepare a polyamide 56 melt;

(2) conveying the polyamide 56 melt prepared in the step (1) to a spinning manifold through a melt pipeline for drawing to prepare a primary yarn;

(3) and (3) carrying out heat preservation, cooling, oiling, pre-networking, multi-stage stretching, tension sizing, relaxation sizing, main networking and winding on the primary yarn prepared in the step (2) to obtain the high-strength polyamide 56 industrial yarn.

In some preferred embodiments of the present invention, the high viscosity polyamide 56 resin is heated and melted in step (1) using a single screw or a twin screw.

In some preferred embodiments of the invention, the melt shear rate can be increased by adopting twin-screw heating, the melt viscosity is more uniform, the subsequent high-power drafting can be met, and the quality of the prepared industrial yarn is better.

In some preferred embodiments of the present invention, the method for preparing the high-strength polyamide 56 industrial yarn further comprises an online water spraying process during the heating process of the single screw or the double screws, an online melt viscosity detector is arranged in the spinning manifold, the viscosity change is monitored in real time, and the moisture adding amount is adjusted through the viscosity change.

In some preferred embodiments of the present invention, the relative viscosity of the 96% sulfuric acid of the high viscosity polyamide 56 resin in step (1) is 3.3 to 4.0, preferably 3.4 to 3.8, and more preferably 3.5 to 3.6; and/or the water content of the high-viscosity polyamide 56 resin is 300-550 ppm, preferably 350-500 ppm, and more preferably 400-450 ppm.

In other preferred embodiments of the present invention, the drawing in step (2) is performed by ejecting the melt of the polyamide 56 obtained in step (1) through a spinneret of a spinning beam to obtain the as-spun yarn; and/or the temperature of the spinning manifold is 280-295 ℃, preferably 283-293 ℃, and more preferably 285-290 ℃; and/or the pressure of a spinning assembly of the spinning manifold is 13-25 MPa, preferably 15-20 MPa, and more preferably 17-18 MPa.

In other preferred embodiments of the invention, in the step (3), a slow cooling device is adopted for heat preservation, the slow cooling device is a hot jacket which is arranged at the lower part of the spinneret plate and is closely adjacent to the spinneret plate, so as to ensure that the nascent fiber is uniformly and slowly cooled, the length and the temperature of the hot jacket are changed along with the specification of the spinneret plate and the fineness of the filament bundle, wherein the slow cooling height refers to the thickness of the hot jacket, the slow cooling height is 100-350 mm, preferably 200-300 mm, and the slow cooling temperature is 250-320 ℃, preferably 270-300 ℃; and/or the cooling is air cooling by cross air blowing or circular air blowing, and the air cooling speed is 0.4-0.9 m/s, preferably 0.6-0.8 m/s; the air temperature of the air cooling is 16-25 ℃, and preferably 18-22 ℃; the air-cooled air humidity is 60-90%, and preferably 75-85%; and/or the presence of a gas in the gas,

the concentration of the oil used in oiling is 8-100 wt%, more preferably 65-100 wt%, the dynamic viscosity of the oil is 300mPas, preferably 200mPas, more preferably 100mPas, in one embodiment, the oil is selected from N-350 (available from Nippon oil and fat pharmaceutical Co., Ltd.), N-353 (available from Nippon oil and fat pharmaceutical Co., Ltd.), NEO TEX-903(A) (available from Shanghai Bikahm chemical Co., Ltd.), D-3088 (available from Nantong Henzhi chemical Co., Ltd.), dakaoNeat oil (available from Germany Dakoku Co., Ltd.), TCP-60 Chinlon industrial yarn/cord oil (available from Tianjin chemical Co., Ltd.), TCP-80 Chinlon industrial yarn/cord oil (available from Tianjin chemical Co., Ltd.), TC 2 (available from Tianjin chemical Co., Ltd.), Scheimmer & Schwarz), Germany Scheimer TC-365 (available from Germany Scheimer & Scheimer chemical Co., Ltd.), N-14686 (available from Tianjin chemical Co., Ltd.), N-1152 (available from Germany chemical Co., Ltd., N-3632, preferably from Johnson, N-1355, N-700, N-33, Mitsu chemical company, Mitsu chemical company Mitsu, preferably 1, Mitsu chemical company Mitsu, Mitsu-36, Mitsu chemical Co,

the oiling is carried out by adopting an oil nozzle, an oil tanker or an oil lip oiling mode, for example, 2 or more oil nozzles, oil tankers or oil lips are adopted for oiling, and 2 oil nozzles are preferably adopted for oiling; and/or the height of the oil nozzle from the spinneret plate is more than or equal to 3m, preferably more than or equal to 3.5m, and more preferably more than or equal to 4 m; and/or the width of the oil nozzle is 8-25 mm, preferably 10-22 mm, and more preferably 12-18 mm; and/or the oiling rate is 0.6-2.0%, preferably 0.8-1.5%, and more preferably 1.0-1.2%.

The pre-network pressure is 1-2.5 bar, preferably 1.5-2.0 bar; and/or the presence of a gas in the gas,

the stretching process adopts 5 pairs of hot rollers and is divided into four stages of stretching, and the stretching process comprises the following steps: feeding oiled nascent yarn to a first pair of hot rollers, performing primary pre-stretching between the first pair of hot rollers and a second pair of hot rollers, performing secondary main stretching between the second pair of hot rollers and a third pair of hot rollers, performing tertiary main stretching between the third pair of hot rollers and a fourth pair of hot rollers and performing tension heat setting, and performing fourth-stage secondary stretching between the fourth pair of hot rollers and a fifth pair of hot rollers and performing relaxation heat setting; among them, preferred are: the stretching ratio of the first-stage stretching is 1.0-1.1; and/or the stretching multiple of the second-stage stretching is 3.0-4.0; and/or the stretching multiple of the third stage stretching is 1.3-1.6; and/or the stretching multiple of the fourth stage stretching is 0.9-1.0; and/or the total stretching multiple of the stretching is preferably 4.4-6.0; and/or the temperature of the tension heat setting is 180-230 ℃, preferably 200-220 ℃; and/or the temperature of the relaxation heat setting is 120-200 ℃, preferably 140-180 ℃; and/or the speed retraction of the fourth heat roller pair and the fifth heat roller pair is 50-200 m/min, preferably 100-150 m/min; and/or the main network pressure is 2.5-4.5 bar, preferably 3.0-3.5 bar; and/or the winding speed is 2200 to 3300m/min, preferably 2500 to 3000m/min, and more preferably 2600 to 2800 m/min.

In some preferred embodiments of the present invention, in order to obtain the high-strength polyamide 56 industrial yarn of the present invention, various parameters such as index, slow cooling parameter, oiling method, etc. of the high-viscosity polyamide 56 resin can be simultaneously controlled, so as to obtain the high-strength polyamide 56 industrial yarn with better mechanical property and humidity resistance.

On the other hand, the invention also provides the application of the high-strength polyamide 56 industrial yarn in the fields of sewing threads, tire cord threads, air bag yarns, demolding cloth, water cloth, canvas, safety belts, ropes, fishing nets, industrial filter cloth, conveying belts, parachutes, tents and bags.

Due to the adoption of the scheme, the invention has the beneficial effects that:

first, the raw material for producing the low-viscosity polyamide 56 resin used in the present invention is produced by a biological method, is a green material, does not depend on petroleum resources and does not cause serious pollution to the environment, and can reduce the emission of carbon dioxide and the generation of greenhouse effect.

Secondly, the high-viscosity polyamide 56 resin of the invention has the advantages of high viscosity, large molecular weight, narrow molecular weight distribution, low oligomer content, high thermal crystallization temperature and narrow width of thermal crystallization peak half-peak width.

Thirdly, the high-strength polyamide 56 industrial yarn has better mechanical property and humidity resistance.

Fourthly, the preparation method of the high-strength polyamide 56 industrial yarn provided by the invention has good manufacturability and quality stability, the number of times of interrupting monofilaments and the number of broken filaments in the production process are small, the production efficiency is high, and the production cost is low.

Fifthly, the high-strength polyamide 56 industrial yarn can be prepared by adopting conventional polyamide 6 and polyamide 66 industrial yarn equipment, the spinning equipment is not required to be modified, the yield can be improved, the production cost can be reduced by optimizing the quality of the polyamide 56 resin and the spinning process, and huge benefits are brought to spinning enterprises.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to the invention, through carrying out resin humidity conditioning treatment on the tackified low-viscosity polyamide 56 resin, the problem that the industrial yarn is easy to damage in the subsequent drawing preparation process due to the fact that the melt fluidity is poor because the water content of the resin is reduced is solved. In addition to the relative viscosity and the water content, the research and development personnel experimentally found that the oligomer content, the molecular weight distribution, the thermal crystallization peak temperature and the thermal crystallization half-width temperature of the high-viscosity polyamide 56 resin have important influences on the performance and the production process of the industrial yarn, and the performance parameters of the industrial yarn need to be limited.

In some preferred embodiments of the present invention, the relative viscosity of the 96% sulfuric acid of the high viscosity polyamide 56 resin is 3.2 to 3.8, preferably 3.3 to 3.6, and more preferably 3.4 to 3.5; and/or the water content of the high-viscosity polyamide 56 resin after the resin humidity conditioning treatment is 300-600 ppm, preferably 350-550 ppm, and more preferably 400-500 ppm.

Preferably, the number average molecular weight of the high-viscosity polyamide 56 resin is 25000-50000, preferably 30000-45000, and more preferably 35000-40000; and/or the number average molecular weight distribution of the high-viscosity polyamide 56 resin is 1.5-2.2, preferably 1.7-2.1, and more preferably 1.8-2.0; and/or the oligomer content of the high-viscosity polyamide 56 resin is less than or equal to 1.0 wt%, preferably less than or equal to 0.8 wt%, and more preferably less than or equal to 0.6 wt%; and/or the thermal crystallization peak temperature of the high-viscosity polyamide 56 resin is more than or equal to 208 ℃, preferably more than or equal to 212 ℃, and more preferably more than or equal to 215 ℃; and/or the width of the thermal crystallization peak half width of the high-viscosity polyamide 56 resin is less than or equal to 10 ℃, preferably less than or equal to 8 ℃, and more preferably less than or equal to 6 ℃; and/or the oligomer of the high viscosity polyamide 56 resin comprises one or more of a cyclic mono-, cyclic dimer-, cyclic trimer of adipic acid and pentanediamine.

In some preferred embodiments of the present invention, the method for preparing the high viscosity polyamide 56 resin comprises the steps of:

(1) drying low-viscosity polyamide 56 resin with the relative viscosity of 2.4-2.8 at high temperature to obtain tackifying polyamide 56 resin;

(2) and (2) subjecting the tackifying polyamide 56 resin obtained in the step (1) to resin humidity conditioning treatment to obtain the high-viscosity polyamide 56 resin.

Preferably, in the step (1), the high-temperature drying treatment is vacuum pumping or inert gas protection, and the vacuum degree during the vacuum pumping is-0.05 to-0.1 Mpa; and/or the temperature of the high-temperature drying treatment is 150-200 ℃, and preferably 160-180 ℃; and/or the time of the high-temperature drying treatment is 10-30 hours, preferably 15-25 hours; and/or the equipment for high-temperature drying treatment is a vacuum drum dryer or a continuous dehumidifying hot nitrogen dryer; and/or the tackifying polyamide 56 resin has a relative viscosity of 3.2-3.8 and a water content of 30-200 ppm.

Preferably, in the step (2), the moisture content of the high-viscosity polyamide 56 resin subjected to resin moisture conditioning treatment is 300-600 ppm; and/or the temperature of the resin humidity adjustment treatment is 80-110 ℃, the humidity adjustment treatment is carried out by adopting nitrogen mixed with water vapor, and the dew point of the nitrogen is controlled within the range of-20 ℃ to 20 ℃.

The high-viscosity polyamide 56 resin subjected to the resin humidity conditioning treatment is used as a raw material, or online water spraying and humidity conditioning treatment is carried out in the melting process, so that the high-strength humidity-resistant polyamide 56 industrial yarn can be obtained.

In some preferred embodiments of the invention, the breaking strength of the high-strength polyamide 56 industrial yarn is 8.0-10.0 cN/dtex, preferably 8.3-9.5 cN/dtex, more preferably 8.6-9.3 cN/dtex; and/or after water bath treatment, the breaking strength retention rate of the high-strength polyamide 56 industrial yarn is more than or equal to 88%, preferably more than or equal to 90%, and more preferably more than or equal to 92%; and/or after the industrial yarn is subjected to humidity conditioning treatment, the breaking strength retention rate of the high-strength polyamide 56 industrial yarn is not less than 90%, preferably not less than 93%, and more preferably not less than 95%.

Preferably, the breaking elongation of the high-strength polyamide 56 industrial yarn is 16-24%, preferably 17-22%, and more preferably 18-20%; and/or after the water bath treatment, the breaking elongation of the high-strength polyamide 56 industrial yarn is less than or equal to 33 percent, preferably less than or equal to 28 percent, and more preferably less than or equal to 25 percent; the elongation fluctuation is less than or equal to 10 percent, preferably less than or equal to 8 percent, and more preferably less than or equal to 6 percent; and/or after the industrial yarn is subjected to humidity conditioning treatment, the breaking elongation of the high-strength polyamide 56 industrial yarn is less than or equal to 27%, preferably less than or equal to 26%, and more preferably less than or equal to 25%; the elongation fluctuation is 3% or less, preferably 2% or less, more preferably 1% or less.

Preferably, the water bath treatment temperature is 70-110 ℃, preferably 75-100 ℃, more preferably 80-90 ℃, and the water bath treatment time is 20-60 min, preferably 30-50 min; and/or the humidity adjusting temperature is 18-30 ℃, preferably 20-27 ℃, the humidity adjusting humidity is 60-95%, and the humidity adjusting time is 1-48 h, preferably 4-40 h, and more preferably 8-30 h.

Preferably, the water bath treatment temperature is 90 ℃ and the time is 30 min; and/or the humidity adjusting treatment temperature is 20 ℃, the relative humidity is 65.0%, and the time is 24 h.

The filament breakage frequency of the high-strength polyamide 56 industrial filament is less than or equal to 5 per 24h, preferably less than or equal to 3 per 24h, and more preferably less than or equal to 2 per 24 h; and/or the broken filaments of the high-strength polyamide 56 industrial filaments are less than or equal to 10 filaments/10 kg packages, preferably less than or equal to 8 filaments/10 kg packages, and more preferably less than or equal to 5 filaments/10 kg packages.

In some preferred embodiments of the present invention, the method for preparing the high-strength polyamide 56 industrial yarn comprises the following steps:

(1) heating the high-viscosity polyamide 56 resin to a molten state by adopting a single screw or a double screw to obtain a polyamide 56 melt; or the high-viscosity polyamide 56 resin is directly subjected to online water spraying and humidity conditioning treatment in the single-screw or double-screw heating and melting process to obtain a polyamide 56 melt;

(2) conveying the polyamide 56 melt obtained in the step (1) to a spinning manifold through a melt pipeline for drawing to obtain a primary yarn;

(3) and (3) carrying out heat preservation, cooling, oiling, pre-networking, multi-stage stretching, tension sizing, relaxation sizing, main networking and winding on the primary raw silk obtained in the step (2) to obtain the high-strength polyamide 56 industrial silk.

In some preferred embodiments of the present invention, the relative viscosity of the 96% sulfuric acid of the high viscosity polyamide 56 resin in step (1) is 3.3 to 4.0, preferably 3.4 to 3.8, and more preferably 3.5 to 3.6; and/or the water content of the high-viscosity polyamide 56 resin is 300-550 ppm, preferably 350-500 ppm, and more preferably 400-450 ppm.

In some preferred embodiments of the present invention, in the step (1), the melt of the polyamide 56 has a relative viscosity of 3.3 to 3.8.

In some preferred embodiments of the present invention, in the step (2), an in-line melt viscosity detector is provided in the spinning beam.

In other preferred embodiments of the present invention, the drawing in step (2) is performed by ejecting the melt of the polyamide 56 obtained in step (1) through a spinneret of a spinning beam to obtain the as-spun yarn; and/or the temperature of the spinning manifold is 280-295 ℃, preferably 283-293 ℃, and more preferably 285-290 ℃; and/or the pressure of a spinning assembly of the spinning manifold is 13-25 MPa, preferably 15-20 MPa, and more preferably 17-18 MPa.

In other preferred embodiments of the invention, in the step (3), a slow cooling device is adopted for heat preservation, the slow cooling height is 100-350 mm, preferably 200-300 mm, and the slow cooling temperature is 250-320 ℃, preferably 270-300 ℃; and/or the cooling is air cooling by cross air blowing or circular air blowing, and the air cooling speed is 0.4-0.9 m/s, preferably 0.6-0.8 m/s; the air temperature of the air cooling is 16-25 ℃, and preferably 18-22 ℃; the air-cooled air humidity is 60-90%, and preferably 75-85%; and/or the presence of a gas in the gas,

the concentration of the oil used for oiling is 8 to 100 wt%, more preferably 65 to 100 wt%, the oil has a kinematic viscosity of 300mPas or less, preferably 200mPas or less, more preferably 100mPas or less, in one embodiment, the oil is selected from N-350 (available from Nippon Song oil and fat pharmaceuticals Co., Ltd.), N-353 (available from Nippon Song oil and fat pharmaceuticals Co., Ltd.), NEO TEX-903(A) (available from Shanghai Bikahm chemical Co., Ltd.), D-3088 (available from Nantong Henhuang chemical Co., Ltd.), dakaoNeat oil (available from Germany Dakko Co., Ltd.), TCP-60 Chinlon industrial yarn/cord oil (available from Tianjin chemical Co., Ltd.), TCP-80 Chinlon industrial yarn/cord oil (available from Tianjin chemical Co., Ltd.), TC1152 (available from Germany chemical Co., Zschimmer & Schwarz), TETC-35 (available from Germany chemical company Zschimmer & Schwarz), TEOG-14686 (available from Germany chemical company Zschimmer & Scheim, N-3613532, N-30, preferably one or more of Johnson NCh 3, NCH 3, III, NCH 3, NCH,

the oiling is carried out by adopting an oil nozzle, an oil tanker or an oil lip oiling mode, for example, 2 or more oil nozzles, oil tankers or oil lips are adopted for oiling, and 2 oil nozzles are preferably adopted for oiling; and/or the height of the oil nozzle from the spinneret plate is more than or equal to 3m, preferably more than or equal to 3.5m, and more preferably more than or equal to 4 m; and/or the width of the oil nozzle is 8-25 mm, preferably 10-22 mm, and more preferably 12-18 mm; and/or the oiling rate is 0.6-2.0%, preferably 0.8-1.5%, and more preferably 1.0-1.2%.

The pre-network pressure is 1-2.5 bar, preferably 1.5-2.0 bar; and/or the presence of a gas in the gas,

the stretching process adopts 5 pairs of hot rollers and is divided into four stages of stretching, and the stretching process comprises the following steps: feeding oiled nascent yarn to a first pair of hot rollers, performing primary pre-stretching between the first pair of hot rollers and a second pair of hot rollers, performing secondary main stretching between the second pair of hot rollers and a third pair of hot rollers, performing tertiary main stretching between the third pair of hot rollers and a fourth pair of hot rollers and performing tension heat setting, and performing fourth-stage secondary stretching between the fourth pair of hot rollers and a fifth pair of hot rollers and performing relaxation heat setting; among them, preferred are: the stretching ratio of the first-stage stretching is 1.0-1.1; and/or the stretching multiple of the second-stage stretching is 3.0-4.0; and/or the stretching multiple of the third stage stretching is 1.3-1.6; and/or the stretching multiple of the fourth stage stretching is 0.9-1.0; and/or the total stretching multiple of the stretching is preferably 4.4-6.0; and/or the temperature of the tension heat setting is 180-230 ℃, preferably 200-220 ℃; and/or the temperature of the relaxation heat setting is 120-200 ℃, preferably 140-180 ℃; and/or the speed retraction of the fourth heat roller pair and the fifth heat roller pair is 50-200 m/min, preferably 100-150 m/min; and/or the main network pressure is 2.5-4.5 bar, preferably 3.0-3.5 bar; and/or the winding speed is 2200 to 3300m/min, preferably 2500 to 3000m/min, and more preferably 2600 to 2800 m/min.

In some preferred embodiments of the present invention, the application of the high-strength polyamide 56 industrial yarn specifically comprises the wide application of the high-strength polyamide 56 industrial yarn in the fields of sewing thread, tire cord, air bag yarn, release fabric, water cloth, canvas, safety belt, rope, fishing net, industrial filter cloth, transmission belt, parachute, tent and case.

In the present invention, unless otherwise specified, the detection method of each parameter is as follows:

(1) breaking strength: the tensile property of the chemical fiber filaments is measured according to the national standard GB/T14344-2008 test method for the tensile property of the chemical fiber filaments.

(2) Elongation at break: the tensile property of the chemical fiber filaments is measured according to the national standard GB/T14344-2008 test method for the tensile property of the chemical fiber filaments.

(3) Relative viscosity the relative viscosity of the polyamide 56 resin was measured by the concentrated sulfuric acid method using an Ubbelohde viscometer by weighing exactly 0.25. + -. 0.0002g of the dried polyamide 56 resin, adding 50m L of concentrated sulfuric acid (96%) to dissolve it, measuring and recording the flow time t of the concentrated sulfuric acid in a thermostatic water bath at 25 ℃₀And a flow time t of the polyamide 56 resin solution.

The relative viscosity is calculated by the formula: relative viscosity VN ═ t/t₀(ii) a t-solution flow time; t is t₀-solvent flow time.

(4) Water content: measured according to the Karl Fischer water content titrator method.

(5) A method for detecting a molecular weight and a molecular weight distribution, wherein the number average molecular weight (Wn) and the weight average molecular weight (Wm) of a main peak (polymer peak) in an elution curve obtained by Gel Permeation Chromatography (GPC) were calibrated from a standard sample of polymethyl methacrylate (PMMA) using an elution curve (ordinate: signal intensity obtained by a detector and abscissa: elution time), and the molecular weight distribution PDI was weight average molecular weight (Wm)/number average molecular weight (Wn); PDI ═ Wm/Wn; measurement was performed under the conditions of a detector: RI detector; column: 2x PSS 7. mu. PFG L inner M column 300x 8.0mm solvent: hexafluoroisopropanol containing sodium trifluoroacetate at a concentration of 0.05 mol/L; temperature: 40 ℃; flow rate: 1M L/min; injection amount: 100. mu. L; concentration: 3 to 5 g/L).

Sample preparation the polyamide resin or polyamide resin composition obtained in each example and the like was weighed in hexafluoroisopropanol containing 0.01 mol/L of sodium trifluoroacetate so as to be 0.5mg/m L in terms of polyamide resin, and dissolved by stirring at room temperature for 1 hour, and the resulting solution was filtered through a hydrophobic membrane filter (pore size: 0.22 μm) to prepare a sample.

PMMA standard: a STANDARD elution curve (calibration curve) was prepared using STANDARD81506-1EA (number average molecular weight range: 500-27000000) prepared by Fluka.

(6) And (2) carrying out water extraction (weighing), namely accurately weighing about 8g of polyamide 56 resin dried for 7 hours at 130 ℃, placing the polyamide 56 resin into a 500m L round-bottom flask, adding 400g of water, refluxing for 36 hours in a heating jacket, decanting the solution, drying the particles in a constant-weight beaker at 130 ℃ for 7 hours, then plastically packaging the particles in an aluminum plastic bag, reducing the temperature, and weighing to calculate the weight loss of the particles, wherein the low-viscosity polyamide 56 resin is prepared by the method disclosed in CN108503826A or CN108503824A, and the relative viscosity is 2.4-2.8.

(7) Broken filaments (number of times/24 h): and (5) manual statistics.

(8) The number of broken filaments: measured by a hairiness on-line detector during winding.

(9) Thermal crystallization peak temperature, thermal crystallization peak half width: DSC measurement, in nitrogen atmosphere, heating from 30 deg.C to 270 deg.C at a heating rate of 10 deg.C/min, maintaining for 5min, and cooling from 270 deg.C to 30 deg.C at a cooling rate of 10 deg.C/min.

(10) Water bath treatment: taking a section of high-strength polyamide 56 industrial yarn, pre-tensioning the high-strength polyamide 56 industrial yarn by 0.05 +/-0.005 cN/dtex, marking the middle two ends of the high-strength polyamide 56 industrial yarn by 50.00cm, wrapping the high-strength polyamide 56 industrial yarn with gauze, putting the high-strength polyamide 56 industrial yarn into a water bath at 90 ℃ for boiling for 30min, drying a sample, and calculating by adopting the following formula: humidifying industrial yarn: according to GB/T6529-2008, the high-strength polyamide 56 industrial yarn package is placed in a constant-temperature and constant-humidity room, the temperature is 20 ℃, the relative humidity is 65%, and the time is 24 hours.

The retention ratio of breaking strength after water bath treatment (breaking strength after water bath treatment/breaking strength before water bath treatment) was × 100%.

The retention ratio of the breaking strength after the moisture control treatment of the industrial yarn (breaking strength after the moisture control treatment of the industrial yarn/breaking strength before the moisture control treatment of the industrial yarn) is × 100%.

The breaking strength is measured according to the national standard GB/T14344-.

(11) The fluctuation of the elongation at break after the water bath treatment is the elongation at break before the water bath treatment-the elongation at break after the water bath treatment;

and (3) the elongation at break fluctuation after the industrial yarn humidity conditioning treatment is equal to the elongation at break before the industrial yarn humidity conditioning treatment-the elongation at break after the industrial yarn humidity conditioning treatment.

The elongation at break is determined according to the national standard GB/T14344-.

(12) Dynamic viscosity of oil agent: according to the national standard GB/T265-1988 petroleum product kinematic viscosity determination method and kinetic viscosity calculation method.

The slow cooling device used in the following application examples and comparative examples is a hot jacket located immediately below the spinneret to ensure uniform and slow cooling of the as-spun filaments, and the length and temperature of the hot jacket vary with the specifications of the spinneret and the fineness of the filament bundle, wherein the slow cooling height is the thickness of the hot jacket and the slow cooling temperature is the ambient temperature around the filament bundle.