JPH04174713A - Production of high-strength polyamide yarn - Google Patents

Abstract

PURPOSE:To obtain the title yarn having high strength, high toughness and high durability by operating a heating column, a cooler, a crystallization promoting device, finishing oil supplying devices and a drawing device under specific conditions, respectively. CONSTITUTION:Yarn Y spun from a spinneret 1 is passed through a heating column 2 to heat an atmosphere at least 10cm from the spinneret at the melting point of polyamide to 400 deg.C, preferably 280-320 deg.C and sprayed with cold air at <=80 deg.C by a cooler 3. The yarn is treated with steam under 20-200mm H2O pressure at 80-150 deg.C for 0.02-1.0 second for by a crystallization promoting device 4, provided with an aqueous emulsion finishing oil by a finishing oil supplying device 5 and with a nonaqueous finishing oil having 150-200 poise under 0.5-1.5g/d tension by a finishing oil supplying device 5'. The necking point is retained between a feed roll 7 and a draw roll 8 at 10-60 deg.C at a distance from the roll 7 of 3-10cm for 0.5-2.5 seconds after supply of the aqueous finishing oil.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for producing high-strength polyamide fibers, particularly for use in tire cords, power transmission belts, conveyor belts, fishing nets, tarpaulins, ropes, tents, and hoses. , Concerning a method for producing high-strength polyamide fibers that can industrially produce polyamide fibers with high strength, toughness, and high durability suitable for industrial use such as sewing thread in a stable state at a high yield. It is something.

[Prior Art] Polyamide fibers have high strength and are excellent in toughness, heat resistance, impact resistance, etc., and are therefore preferred for use in various industrial applications. In recent years, there has been a demand for higher strength of the negative layer because higher strength can reduce the amount of interest used in products, reduce costs and reduce weight.

In the past, many technologies have been disclosed for achieving high strength of polyamide fibers, but in particular, we have developed a technology that not only increases the strength of the raw yarn itself, but also has excellent strength retention during the processing process leading to the product, and has high toughness. A method for producing polyamide fibers having excellent fatigue resistance is disclosed, for example, in Japanese Patent Application Laid-Open No. 1-168915. The method described in this publication involves cooling and solidifying the spun yarn, and then using low pressure steam at 80 to 150°C with an underwater pressure horn of 20 to 200 mm to heat the yarn by 0.02 to 1.
．． After being treated for 0 seconds, a non-aqueous oil agent is applied, and then continuous multi-stage hot stretching is carried out, and the obtained polyamide fibers have specific fiber structure parameters and have a width of 0.01 to 100% over the entire surface layer of the filament. 1μ, length 0.1~10μ
A large number of irregularities are uniformly formed, and the irregularities are formed in long stripes in the direction of the fiber axis, and the fiber has excellent fatigue resistance.

[Problems to be Solved by the Invention] The above-mentioned Japanese Patent Application Laid-Open No. 1-168915 discloses a method for producing polycapramide fiber, but in the case of polyhexamethylene adipamide fiber, it is sufficient to apply it as is. It is difficult to obtain effective results. Furthermore, when polycapramide fibers are produced by direct spinning/drawing, it is desired to further improve stability and yield.

The purpose of the present invention is to improve the method disclosed in JP-A-1-168915, and to produce industrially stable polyamide fibers having particularly high strength, high toughness, and high heat resistance.
The object of the present invention is to provide a technique for manufacturing the fibers with a high yield, and furthermore, to provide a stable and high-yield manufacturing technique that can also be applied to polyhexamethylene adipamide fibers.

[Means and effects for solving the problems] The present invention provides a method for producing high-strength polyamide fibers, in which (a) yarn spun from a spinneret is spun in an atmosphere at least 10 cm from the spinneret that is above the melting point of the polyamide; 400
passing through a high-temperature atmosphere heated to a temperature of °C; (0) blowing cold air of 80 °C or less onto the yarn that has passed through the heated atmosphere to cool and solidify it; (c) cooling and solidifying the yarn; , underwater pressure 20~200m
(m) Leading the yarn into a crystallization accelerator filled with high-temperature steam at a temperature of 80 to 150°C and steaming it for 0.02 to 1.0 seconds; (d) Then applying a water-based emulsion oil to the steam-treated yarn; After that, 0.5-1.5g
/d while applying a tension of 150 to 200Pois
(e) Applying a non-aqueous oil agent as described above; (e) Continue leading the yarn to which the oil agent has been applied to a further drawing process, and adjusting the necking point in the first stage drawing to a) 10 to 60°C; between the feed roll and the first draw roll b) between the 3 and 10 marks from the final contact point between the feed roll and the yarn adjusted to 10 to 60°C C) after applying the water-based emulsion oil agent O95 to 2 .5
A method for producing high-strength polyamide fibers, characterized in that the manufacturing time is between seconds.

(2) The polyamide fiber is produced using a polyhexamethylene azyme method.

A method for producing high-strength polyamide fibers.

The present invention will be explained in detail using the drawings. The drawing is a schematic front view of a direct spinning and drawing apparatus for polyamide fibers used in carrying out the method according to the present invention.

Polyamide fiber spun from spinneret 1 (hereinafter referred to as yarn Y)
) Y is the heating cylinder 2 provided directly below the spinneret 1
, a cooling device 3, a crystallization accelerator 4, and a water-based emulsion oil is applied in an oil supply device 5, and then transferred to a take-up roll 6.
The film is then wound around a feed roll 7, and then drawn with a non-aqueous oil in an oil supply device 5'. Stretching is performed by a feed roll 7, a first draw roll 8, a second draw roll 9, and a third draw roll 10. The drawn yarn Y passes through a relaxation roll 11, reaches a winder 12, and is wound up.

The heating cylinder 2 provided directly below the spinneret 1 is such that the atmosphere immediately below the spinneret 1 is preferably filled with nitrogen gas or water vapor, and the atmosphere of at least 10 cm is heated to a temperature above the melting point of the polyamide and below 40°C. It's heated.

The inner atmosphere of the heating cylinder 2 is preferably 250 to 350°C.
, more preferably 280 to 320°C or less, and the length of the high temperature atmosphere is preferably 10 to 100 cm, more preferably 20 to 50 cm.

If the temperature of the high-temperature atmosphere is too high or too long, spinning problems will occur, such as polymer bending or dripping on the spinneret surface, or swaying and fusing of single yarns within the yarn. On the other hand, if the temperature of the high-temperature atmosphere is low or short, the viscosity of the spun yarn increases rapidly, causing tension unevenness in the yarn, making it impossible to obtain uniform fibers.

Further, it is preferable that the high temperature atmosphere immediately below the cap is filled with an inert gas for the polyamide.

If the oxygen concentration in the high-temperature atmosphere is high, the surface of the spun yarn will deteriorate due to thermal oxidation and become colored, and the surface of the spinneret will become extremely dirty. As a result, the strength of the yarn obtained decreases, and fuzz and yarn breakage occur frequently. As the inert gas, nitrogen gas or water vapor is usually used.

The cooling device 3 is a Uniflow one type, an annular natural suction type,
Although an annular blowing method or the like can be used, a uniflow type facing-to-face (one-side blowing, one-side suction) method can cool the yarn most efficiently.

The yarn Y cooled by passing through the cooling device 3 is passed through a crystallization promoting device 4 to promote crystallization of the surface layer of each single yarn forming the yarn Y. The crystallization promoting device 4 is preferably a cylindrical heating device filled with high temperature steam. Even if the steam used is saturated, it is more than 50%.
Although superheated steam containing water may be used, a low pressure of 20 to 200 mmHzO is preferable. Also yarn Y
crystallization accelerator 4 while blocking the accompanying airflow.
It is necessary to control the temperature, and it is preferable to install an accompanying air flow exclusion plate or the like on the top of the crystallization promoting device 4.

Furthermore, the atmospheric temperature in the crystallization promoting device 4 is 8.
0 to 150°C, particularly 90 to 120°C is preferred.

Appropriate conditions for the steam treatment in the crystallization accelerator 4 are such that the degree of orientation of the yarn taken off by the take-up roll 6 is 7x10-8 to 30x10-3 in terms of birefringence, preferably 10x.
It is changed according to the take-up speed, yarn fineness, etc. so that it is in the range of 10-3 to 25X10-8.

The birefringence of the yarn Y taken up by the take-up roll 6 is 7X1
If the birefringence is less than 0-3, crystallization of the surface layer of the fiber has not progressed sufficiently, so particularly high toughness and high durability cannot be obtained.If the birefringence exceeds 30X10-3, the oriented crystallization progresses too far into the inside of the fiber. Therefore, the magnification of the subsequent drawing cannot be made high, and the strength of the yarn Y after drawing cannot be increased. The residence time of yarn Y in the cylinder is 0.02 to 1,
0 seconds is preferable. If it is less than 0.02 seconds, the crystallization treatment of the fiber surface layer will be insufficient; If the time exceeds 0 seconds, crystallization will extend to the inside of the fiber, making it impossible to obtain a polyamide fiber with high strength.

That is, the conditions of the polymer physical properties, the heating tube 2, the cooling device 3, and the crystallization promoting device 4 are combined so that the birefringence of the yarn Y taken up by the take-up roll 6 is 7X1.0-'' to 30X10-''. By doing so, a synergistic effect can be obtained.

As the type of oil supply device 5, a roll type, a guide type, etc. can be used. The oil supply device 5 applies aqueous emulsion oil to the yarn as an effective component of 0.02 to 1.5.
It is preferable to give a generous percentage. More preferably 0.0
Apply 5-1.0% by weight of oil.

The yarn coated with a water-based emulsion oil is taken up by a take-up roll, and the take-up rolls are a pair of split rolls (driving roll and non-driving roll), a Nelson type, and a single roll type. It will be done. The take-up roll is a cooling roll of 308C or less, preferably 10 to 25C, and the contact time with the yarn is 0.2 seconds or more. Since the drawn yarn Y has been subjected to high-temperature steam treatment in the crystallization promoting device 4, it is necessary to cool it first.

Although there is a method of cooling the yarn Y by blowing cold air onto it, it is most preferable to use the method of bringing the yarn into contact with the cooled take-up roll as described above without increasing the size of the apparatus.

The viscosity measured at 25° C. while applying a tension of 0.5 to 1.5 g/d to the yarn between the take-up roll 6 and the feed roll 7 is 150 to 200 P.

ISE non-aqueous oil is applied by the oil supply device 5'. In the case of a non-aqueous oil agent, if the tension is less than 0.5 g/d, the oil agent cannot be applied uniformly, and the single yarn forming the yarn Y on the oil supply roll 5' may become sagging or the yarn may sway, and the oil may continue to be applied. The necking point in the stretching process that is performed varies. In this case, thread breakage and fluffing are likely to occur, leading to a decrease in stretching yield.

Next, the yarn Y is stretched in the first stage between the feed roll 7 and the first draw roll 8, stretched in the second stage between the first draw roll 8 and the second draw roll 9, and then stretched in the second stage between the feed roll 7 and the first draw roll 8. After performing the third stage stretching between the third draw roll 10 and the third draw roll 10, the film is relaxed by 10% or less, preferably 2 to 8%, between the third draw roll 10 and the relaxation roll 11, and then wound up. .

Feed roll 7 is at room temperature to 50°C, first draw roll 8
C80-180℃, 2nd do O-0-)Iy 9 is 160
-210°C 1. The temperature of the third draw roll 10 is preferably below the melting point of polyamide and 170°C or above, for example, 180-220°C in the case of polycapramide, 180-235°C in the case of polyhexamethylene adipamide. It is preferable that the temperature of each of the rolls mentioned above be surrounded by a box with good heat insulation in the previous stage, and that gas heated to a temperature of 1 degree or more at the center of the surface of the roll is actively introduced into the sealed area. Air, nitrogen, water vapor, etc. are used as the gas. The temperature of the relaxing roll 11 placed last is 220°C or lower, preferably 160°C or lower.

The yarn Y has a stretching ratio of 60 to 80% of the total stretching ratio between the feed roll 7 and the first draw roll 8, and a ratio of 1.05 to 2.0 between the first draw roll 8 and the second draw roll 9. times,
1 between the second draw roll 9 and the third draw roll 10
．． 05 to 2.0 times. The total stretching ratio is 4.0
Above, preferably 4.5 to 6.5 times.

The most important thing in drawing is that the yarn Y to which the oil agent has been applied is subsequently led to the drawing process, and the feed roll 7 and the first draw roll 8 whose necking point in the first stage is adjusted to 108C to 60C are used. 3 to 3 from the final contact point S between the feed roll 7 and the yarn Y
10 cm, and the aqueous emulsion oil agent is present between 095 and 25 seconds after application.

=14- If the temperature of the feed roll 7 is not adjusted to 10° C. to 608° C. and is less than 10° C., the necking point largely moves to the first draw roll 8 side, and the necking point I
Not only is this not done at a fixed position, but the single yarn is likely to break, and may move to the feed roll 7 side and exceed 3 to 10 cm from the final contact point S between the feed roll 7 and the yarn Y.

The necking point is a position between 3 and 10 cm from the final contact point S between the feed roll 7 and the yarn Y, and is 0.5 to 2.5 cm after applying the water-based emulsion oil.
It's between seconds. If the distance is less than 3 cm from the final contact point S between the feed roll 7 and the yarn Y, the final contact point S
As a result, some of the single yarns forming yarn Y may be cut and wound into the feed roll 7, and if the operation continues, the wound single yarns may be re-combined with other single yarns. It then follows and runs towards the first draw roll 8. In this case, the single yarn is hardly drawn in the first stage, and the cut end becomes fluffy, and loops are likely to occur in the vicinity of the end, resulting in a decrease in quality. On the other hand, when the distance from the final contact point S between the feed roll 7 and the yarn Y exceeds Locm, the necking point becomes stable at a constant position.
, when the necking point touches the first draw roll 8, it is not stretched. That is, it is heated by the first draw roll 8 in an unoriented state, and crystallization is promoted, making high-magnification stretching impossible. The obtained yarn Y has a part in which crystallization is promoted and a part in which it is normally drawn in the length direction, and when attempting to draw at a high magnification during the second stage of drawing which is carried out next, , single thread breakage is likely to occur.

The polyamide fiber produced by the method according to the invention has the following characteristics.

(a) Birefringence/n≧60X10-11 (b) Non-molecular orientation degree ■ measured by fluorescence polarization method is F≦0.
88 (c) The small-angle X-ray scattering image shows a layered four-point scattering image, and the long period (Dm) in the meridian direction and the long period (D
e) Ratio of D e / D m to D e / D m
≧1.35 (d) The coefficient of static friction μ between fibers is μ≦0.15 (e) The width of the entire surface of the filament is 0.01 to 1 μ
A large number of irregularities are uniformly formed, and the irregularities are formed in long stripes in the fiber axis direction.

(f) The relationship between strength T/D and elongation E is T/D≧1, Og/d.T/D The polyamide fiber obtained by the present invention has a birefringence (/n) as high as 60×10-” or more, and its molecular chains are highly oriented to a degree comparable to or higher than that of conventional fibers. However, the degree of amorphous molecular orientation measured by fluorescence polarization method (CF) is 0.88.
Below, it is usually 086 or less, which is lower than the conventional value exceeding 0.88. The characteristics of this measurement method indicate that the degree of orientation of the amorphous portion, particularly in the surface layer portion, is low.

Moreover, the polyamide fiber obtained by the method according to the present invention shows a laminar four-point scattering image in a small-angle X-ray scattering image, and has a long period (Dm) in the meridian direction and a long period (De) in the equatorial direction.
) is characterized by a ratio De/D m of 1°35 or more, that is, a larger De than conventional high-strength polyamide fibers.

The characteristics of small-angle X-ray scattering are consistent with those of general high-speed spun and drawn fibers, and are associated with the development of high fatigue resistance characteristics of the fibers.

Furthermore, the polyamide fiber obtained by the method of the present invention is
The static friction coefficient μ between the fibers is 0.15 or less, and it is characterized by being smaller than conventional polyamide fibers. This is a characteristic characterized by the regularly formed lamellar crystal layer on the surface layer of the fiber filament.

That is, in the polyamide fiber of the present invention, a large number of striped irregularities extending in the fiber axis direction are uniformly formed on the entire surface of the filament, and the irregularities have a width of 0.01 to 1 μm and a length of 0.01 μm.
It is characterized by a thickness of 1 to 1.0μ. The above structure can be observed using a scanning electron microscope. Incidentally, observation of the cross section of the fiber using a polarizing microscope reveals that the unevenness on the fiber surface is a crystal layer having a thickness of 2 to 10 microns, usually 3 to 6 microns.

The surface layer fiber has a two-layer structure consisting of a regular lamellar crystal layer, a thin flexible layer consisting of a low-orientation amorphous part with a low crystal content, and a highly-orientated inner layer protected by an outer layer. ing.

As a result, the polyamide fiber produced by the method of the present invention has a high strength of 10 g/d or more, usually 11 g/d or more, and a product of strength and elongation of 250 g/d% or more, usually 27
It has a toughness of 5 g/d・% or more.

Next, an explanation will be given based on an example. The characteristics of the present invention are measured as follows.

(A) Birefringence/n: Determined using a Nippon Kogaku Kogyo (POT-I) polarizing microscope using white light as a light source and the normal Bereck convencenter method.

(B) The long period Dm in the meridian direction and the long period De in the equatorial direction by small-angle X-rays: Rigaku Denki (Sai-made wide-angle Measured as a radiation source (Dekani 50KV, 150mA.

Slit 1mmφ). Shooting conditions are camera radius 400mm
, film Kodak DEF-5, exposure time 30 minutes.

From the distance r on the small-angle X-ray scattering photograph, Bragg's formula: L
Calculated using =λ/2sin [(tan-'(r/R))/2]. [However, R: camera radius, λ: X-ray wavelength, L: long period (Dm in the meridian direction, De in the equatorial direction)] (C) Amorphous molecular orientation degree V: The sample was coated with the fluorescent agent “WitexRP” [ Resident Chemical (manufactured by...)
The sample was immersed in a 0.2% by weight aqueous solution of 20% by weight at 20° C. for 2 hours, thoroughly washed, and then air-dried to obtain a measurement sample. Japan Spectrum (a
The relative intensity of polarized fluorescence was measured using a FOM-1 polarimeter (manufactured by FOM-1), and was determined by the following formula.

F=4-B/A However, A: Relative viscosity of polarized fluorescence in the direction of the fiber axis B: Relative intensity of polarized fluorescence in the direction perpendicular to the fiber axis (D) Coefficient of static friction between fibers μ: (Rodcr method) Drum shape A sample fiber is set in the axial direction of a cylindrical drum with a notch in the flange using an IKg tension horn.

On the drum, a sample fiber (approximately 50 cm
) and rotate the drum at a low speed of 2 cm/min.

The friction coefficient μ was determined from the tension T generated at that time using the following formula.

μ= (T-W)/(T+W) (E) Scanning electron microscope: Field emission scanning electron microscope S-80 manufactured by Hitachi (Toko)
Using Type 0, the side surface of the fiber was observed at an accelerating voltage of 6 KV.

(F) Tensile strength T/D, residual elongation E1, initial tensile resistance Mi: As defined by JIS-L1017. The sample was taken in a skein shape, left for 24 hours in a temperature-controlled room at 20°C, 60% RI-1, and then subjected to a tensile test period using "Tensilon" UTM-4L model [Toyo Baldwin (fried), sample length 25 cm, tensile speed 3.
Measurement was made at 0 cm/min.

(G) Boiling water shrinkage rate asnw: Take a sample in the form of a skein and leave it in a temperature-controlled room at 20°C and 60% RT-1 for more than 24 hours. Length measured by applying a load equivalent to 1 g/d.

The sample was left in a boiling water bath for 30 minutes under no tension, then taken out from the bath, left in the greenhouse for 4 hours, and then the above load was applied again to measure the length.

It was calculated from the following formula.

JSnw-[(Lo L,)/Lo] xi oo
(%) Copper iodide 0.02% by weight, potassium iodide 0. Nylon 66 chips containing 1% by weight of potassium bromide and 0.1% by weight of potassium bromide and ηr=3.5 were spun using an extruder type spinning machine.

The discharge amount was adjusted so that the total yarn fineness was 1260D. Also, the base is 0. A material having a diameter of 3 mm and 204 holes was used, and the polymer temperature was 285°C. A 10μ cut nonwoven fabric filter was used for filtration. The atmosphere 25 cm below the cap was filled with nitrogen gas at 5 NI/min and passed through a heating cylinder maintained at 300°C, and then taken through a 5 cm long heat insulating zone (=J digits, passed through a 90 cm long facing uniflow chimney). The chimney air was cooled at 20°C and 30°C.
The conditions were set at m/min.

Thereafter, the yarn was passed through a 30 cm crystallization promotion cylinder filled with the water vapor pressure shown in Table 1, and then 0.2% by weight of an effective component of a water-based emulsion oil was applied to the yarn using a roll type oil supply device. Next, the yarn is taken up by an unheated take-up roll that rotates at a predetermined speed, and then, while being stretched by the take-up roll and feed roll, a non-aqueous oil agent is applied to the yarn by 0.8 weight of effective ingredients. How many phrases did you use for %?

Next, one stage of stretching is performed between the first draw roll heated to 125°C, and the second stage is stretched between the second draw roll heated to 220°C.
The film was stretched in three stages, then stretched in three stages with a third draw roll heated to 230°C, relaxed between the third draw roll and a relaxation roll heated to 140°C, and then wound up.

The yarn spinning conditions are shown in Table 1, and the obtained drawn yarn characteristics and drawing state are shown in Table 2.

Examples 1 to 3, which satisfied the method of the present invention, had high strength and high elongation, and had very good drawability with little yarn breakage during drawing.

Comparative Example-1 is a case in which the surface crystallization treatment according to the present invention was not performed, and although it has high strength, the elongation is slightly low, the degree of amorphous orientation is high, and the long period ratio Dm/ De is low,
It did not have the characteristics of the fiber obtained by the method of the present invention, such as a high coefficient of static friction μ, and no improvement in fatigue resistance was observed when it was actually used as a tire cord. In Comparative Example-2, although the surface crystallization treatment of the present invention was performed, the treatment was insufficient, while in Comparative Example-3, the treatment was too strong, and both fiber structure parameters and physical properties were not achieved as intended by the present invention method. And the stretchability was not satisfied.

Comparative Examples 4 to 6 are examples in which the oil supply conditions, the position of the necking point, and the time from surface crystallization treatment to necking are outside the range of the method of the present invention. Also, comparative example-7
is an example in which the thermal atmosphere conditions for the mouthpiece and mandible are not satisfied. In either case, the fiber structure parameters and physical properties targeted by the method of the present invention were not satisfied, and no improvement in stretchability was observed.

(The following is a blank space) [Effects of the Invention] According to the method of the present invention, polyamide fibers having high strength, high toughness, and high durability can be stably produced in high yield by an industrially advantageous direct spinning/drawing method. I can do it.

In addition, the polyamide fibers obtained by the method of the present invention have high toughness with a strength of 10 g/d or more and an elongation of 20% or more. Suitable for rubber reinforcing cords such as car belts, seat belts, sewing threads, fishing nets, and various cover sheets. In particular, it is characterized by being less susceptible to process variations, and as a result, it can be manufactured with uniform quality in good yield, and the manufacturing process can be easily managed.

[Brief explanation of the drawing]

The drawing is a schematic drawing showing one embodiment of the direct spinning drawing method of the present invention. DESCRIPTION OF SYMBOLS 1... Spinneret, 2... Heating tube, 3... Cooling device, 4... Crystallization promotion device, 5.5'... Oil supply device, 6... Take-up roll, 7. ... Feed roll, 8... First draw roll, 9... Second draw roll, 10... Third draw roll, 11... Relax roll, 12... Winder, Y...・Yarn, S...Final contact point

Claims (3)

[Claims] (1) In the method for producing high-strength polyamide fiber, (a) The yarn spun from the spinneret is heated in an atmosphere at least 10 cm from the spinneret to a temperature higher than the melting point of the polyamide and 400 cm above the melting point of the polyamide.
passing through a high-temperature atmosphere heated to a temperature of °C; (b) blowing cold air of 80 °C or less onto the yarn that has passed through the heated atmosphere to cool and solidify it; (c) cooling and solidifying the yarn; , underwater pressure 20~200m
(m) leading to a crystallization accelerator filled with high-temperature steam at a temperature of 80 to 150°C and steaming for 0.02 to 1.0 seconds; (d) then applying a water-based emulsion oil to the steam-treated yarn; After that, 0.5-1.5g
applying a non-aqueous oil agent of 150 to 200 Poise while applying a tension of a) Between the feed roll adjusted to 10 to 60°C and the first draw roll b) Between 3 to 10 cm from the final contact point between the feed roll and the yarn adjusted to 10 to 60°C c) The above 0.5 to 2.5 after applying water-based emulsion oil agent
A method for producing high-strength polyamide fibers, characterized in that the manufacturing time is between seconds. (2) The method for producing high-strength polyamide fibers according to claim 1, wherein the polyamide fibers are polyhexamethylene adipamide fibers. (3) The method for producing high-strength polyamide fibers according to claim 1, wherein the polyamide fibers are polycapramide fibers.