JPH0258363B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Technical Field The present invention relates to a method for producing polyhexamethylene adipamide fiber. More specifically, the present invention relates to a method for producing polyhexamethylene adipamide fibers having excellent fatigue resistance, dimensional stability, strength and elongation and used for rubber reinforcement in tire cords, belts, etc. (b) Prior art Polyhexamethylene adipamide fiber has high strength,
Because of its excellent toughness, heat resistance, dyeability, and color development, it is widely used as a fiber for industrial materials, interior bedding, and clothing. Especially the strength
Due to its excellent toughness, heat resistance, fatigue resistance, and adhesion to rubber, it is widely used as a fiber for tire cords. In recent years, energy-saving technology has been required for tires as well, and tires with lower fuel consumption are being sought.
To this end, tire manufacturers are pursuing tires with lower rolling resistance and lighter weight. Along with this, tire cords are also required to have yarns with higher strength due to a more dimensionally stable yarn arrangement. In addition, improving tire durability not only has an economic effect by extending the life of the tire, but also
This is necessary from the perspective of improving safety, and yarns with better fatigue resistance are also required for tire cords. Compared to nylon 6 fiber, nylon 66 fiber is
It has excellent heat resistance and dimensional stability, and is also more heat resistant than polyethylene terephthalate fiber.
In particular, it has excellent heat and humidity resistance and amine decomposition resistance, but its biggest drawback is that it has lower dimensional stability compared to polyethylene terephthalate fiber. Therefore, in the field of radial carcass where dimensional stability is required, steel, polyethylene terephthalate, rayon, etc. have been mainly used. Steel and rayon have low strength per unit weight, which increases the amount of cord used per tire, causing an increase in tire weight and cost. Polyethylene terephthalate has low heat resistance, particularly low heat and humidity resistance, and therefore its use is limited to truck bus tires, high-speed tires, etc. where the running temperature of the tires is high. Therefore, there was a need to take advantage of the excellent high strength, heat resistance, and fatigue resistance of nylon 66 fibers and further improve dimensional stability. A method for improving the dimensional stability and fatigue resistance of polyester yarn is disclosed in Japanese Patent Publication No. 53-58032.
This method is characterized by melt-spinning polyester, mainly made of polyethylene terephthalate, under high stress and hot drawing the undrawn yarn with a relatively high birefringence of 9 x 10 ^-3 to 70 x 10 ^-3 . , the undrawn yarn take-up speed is 1000 to 2000 m/min
has been adopted. Since this published patent, various studies have been conducted to improve the dimensional stability and fatigue resistance of high-speed spun yarns by drawing them. Regarding polyhexamethylene adipamide fiber, published patent publication 1982-
No. 60012 discloses a method characterized in that polyhexamethylene adipamide is melt-spun and the fiber is drawn at a spinning speed of 2000 m/min or more. However, when the spinning speed is increased and the degree of orientation of the spun yarn is increased, the drawability deteriorates. This tendency is particularly remarkable for polyhexamethylene adipamide, which has a significantly high crystallization rate. Therefore, the higher the spinning speed of polyhexamethylene adipamide, the lower the strength and elongation of the resulting drawn yarn. Generally, the original function of tire cord is as a reinforcing material, and as the strength and elongation of the tire cord decreases, the amount of yarn used in the tire must increase, resulting in an increase in the weight of the tire and an increase in manufacturing costs. (c) Purpose of the Invention The purpose of the present invention is to provide a polyhexamethylene adipamide fiber that not only has excellent strength and elongation even when used as a high-speed spinning yarn, but also has improved dimensional stability and fatigue resistance. is to provide. (d) Structure of the Invention The method for producing polyhexamethylene adipamide fiber according to the present invention involves melting polyhexamethylene adipamide having a formic acid relative viscosity of 50 to 150, discharging it from a spinneret, cooling it and solidifying it. , once wound up at a take-up speed of 1000 m/min or more, then stretched at a speed of 100 m/min.
This is a method for producing polyhexamethylene adipamide fiber, which is characterized by hot drawing at a speed of less than 1 minute. (e) Effects of the invention The high-strength polyhexamethylene adipamide fiber obtained by the present invention has excellent strength and elongation, dimensional stability, and fatigue resistance, and can be used as a tire cord material and a belt material. It can be used as (F) Embodiment The polyhexamethylene adipamide used in the present invention is mainly composed of repeating units of the following formula. Polyhexamethylene adipamide modified by adding up to 10% by weight of other amide-forming units can also be used in the process of the invention. Such small amounts of amide forming units include aliphatic dicarboxylic acids such as sebacic acid and dodecanoic acid, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, aliphatic diamines such as decamethylene diamine, metaxylylene diamine, etc. Aromatic diamines, ω-aminocarboxylic acids such as ε-aminocaproic acid, and lactams such as caprolactam and laurinlactam can be used. It is also possible to use a mixture of polyhexamethylene adipamide with 20% by weight or less of other polyamides such as polycapramide and polyhexamethylene sebacamide. Furthermore, the polyhexamethylene adipamide may contain additives commonly used, such as copper acetate, copper chloride,
Copper compounds such as copper iodide, 2-mercaptobenzimidazole copper complex salts, 2-mercaptobenzimidazole, tetrakis-[methylene-3-(3,5-
Heat stabilizers such as di-t-butyl-4-hydroxyphenyl)-probionate]-methane, light stabilizers such as manganese lactate and manganese hypophosphite, phosphoric acid,
Thickeners such as phenylphosphonic acid and sodium pyrophosphate, matting agents such as titanium dioxide and kaolin, lubricants such as ethylene bisstearylamide and calcium stearate, and plasticizers can be included. The polyhexamethylene adipamide used in the present invention must have a formic acid relative viscosity of 50 or more and 150 or less. What is "formic acid relative viscosity" here?
Polymer concentration 8.4 when polymer is dissolved in 90% formic acid
It is the solution relative viscosity at 25°C of the weight% solution.
When the formic acid relative viscosity is less than 50, the fatigue resistance of the obtained polyhexamethylene adipamide fibers is significantly reduced. If the relative viscosity of formic acid exceeds 150, the drawability will not improve, it will not be possible to obtain a raw yarn with sufficient strength, and the dimensional stability will also decrease. The preferred formic acid relative viscosity of polyhexamethylene adipamide is
It is 60-100. The above polymer dried to a moisture content of 0.1% or less is spun using an extruder type spinning machine, or the above polymer in a molten state after completion of continuous polymerization is guided through a pipe to a spin head and directly spun. The melting temperature at this time is preferably 270°C to 320°C. The spun yarn is cooled with cooling air, applied with an oil agent, taken up with a take-up roller, and then wound. It is also possible to directly wind the film onto a winder after applying the oil without using a take-up roller. The winding speed must be 1000 m/min or more and 6000 m/min or less. If the winding speed is less than 1000 m/min, the fatigue resistance and dimensional stability of the drawn fibers will not improve much. If the winding speed exceeds 6000 m/min, the strength and elongation of the drawn yarn will decrease significantly.
More preferably it is 5000 m/min or less. When the spinning speed of polyhexamethylene adipate fiber is between about 600 m/min and 4000 m/min, the wound yarn absorbs moisture and elongates, making normal winding impossible. Therefore, when the winding speed is 1000 m/min to 4000 m/min, the cooled yarn is steam-set and then wound, or the spun yarn is taken up with a take-up roll and then the next roll is taken up. It is necessary to stretch the film by 2.0 times or less between the two and then wind it up. When the winding speed exceeds 4,500 m/min, the winding tension becomes large, and the paper tube cannot be pulled out of the winding machine due to shrinkage of the yarn, and the end surface of the rolled cheese becomes high. This tendency becomes particularly noticeable when the winding speed exceeds 5000 m/min. In this case, after the spun yarn is taken up by a take-up roll, it is necessary to give it a relaxation of 10% or less between the next roll and then wind it up. The birefringence of the highly oriented polyhexamethylene adipate undrawn yarn before drawing in the method of the present invention is 20×
It is preferably 10 ⁻³ to 50×10 ⁻³ . 20× ^10-3
If it is less than that, the improvement in fatigue resistance and dimensional stability of the drawn fibers will be small. On the other hand, if it exceeds 50×10 ⁻³ , the strength will not be sufficiently developed even if the stretching method is devised as in the present invention. More preferably 25×10 ^-3
or 45×10 ^-3 . In general, for stretching unstretched materials having a large denier such as tire cord, a final stretching roll speed of several hundred m/min to several thousand m/min is employed. Increasing the drawing speed increases productivity, especially in recent years.
With the adoption of the direct spinning/drawing method, high speeds of several thousand m/min have been achieved. However, as a result of our careful consideration,
It has been found that when a highly oriented undrawn yarn is drawn as in the method of the present invention, the influence of the drawing speed on the physical properties of the drawn yarn is much greater than in the case of a low oriented undrawn yarn. In the method of the present invention, it is necessary that the final stretching roll speed is 100 m/min or less.
If it exceeds this range, not only the strength and elongation of the drawn yarn obtained will not be sufficient, but also the fatigue resistance and dimensional stability will decrease. More preferably, it is 50 m/min or less. Physically, there are no disadvantages due to the drawing speed being too low, but the productivity is significantly reduced. Therefore,
The stretching speed that can be practically adopted is 2 m/min or more. For the stretching in the present invention, either one-stage stretching or multi-stage stretching of two or more stages can be adopted. Normally, in the production of high-strength yarn for tire cords, multi-stage stretching has been adopted in order to obtain high tenacity, but in the method of the present invention, one-stage stretching is sufficient to achieve sufficient strength and strength.
Fatigue resistance and dimensional stability can be obtained. This makes the equipment more compact and also saves energy. The stretching rolls used in the present invention include a commonly used Nelson roll unit using two pairs of positively driven rolls, a combination of a positively driven roll and a free roll, or a roll used for stretching multi-filament yarns such as cloth and monofilament. A roll unit combining five to nine positively driven rolls can be used. It is preferable to provide a feed roll in front of the drawing roll to apply tension to the drawn yarn, and to apply a stretch of less than 5% between the feed roll and the drawing roll. Of course, it is also possible to use three or more stages of stretching rolls and apply a stretch of less than 5% between the first stage stretching roll and the second stage stretching roll. It is preferable that the first stage stretching roll has a mirror finish, and the second and subsequent stage stretching rolls preferably have a mirror finish or a satin finish of 10S or less, and a mirror finish and a satin finish may be alternately mixed. The number of turns of the yarn around the Nelson roll unit or the combination of actively driven rolls and free rolls is from 2 to 7 times. The more the surface is mirror-like, the fewer times it is needed, and the rougher the satin finish, the more times it needs to be applied. Although a number of turns of 7 or more is also used, the roll length becomes long and becomes uneconomical. The stretch rolls are usually kept at a temperature above room temperature. For example, in JP-A-58-60012, in which a highly oriented undrawn yarn is drawn by a conventional method, the first drawing roll is held at 80 to 150°C, and the second drawing roll is held at 160 to 240°C. Of course, such a temperature may be employed in the present invention, but in the present invention, stretching can be carried out without any problem even if the stretching rolls are kept at room temperature. This simplifies the equipment and also saves energy. In the method of the present invention, a yarn heating body is provided between the drawing rolls to perform heating drawing. The yarn heating element heats the yarn by contact or non-contact. The temperature of the yarn heating body is 180 to 260°C in the case of contact heating, and 200 to 280°C in the case of non-contact heating. In the case of contact heating, sufficient stretching will not occur below 180℃;
If it exceeds the limit, the yarn will melt. For non-contact heating
If the temperature is lower than 200°C, sufficient stretching will not take place, and if the temperature exceeds 280°C, the yarn will melt. Usually, a hot plate is often used as the yarn heating element, and in the conventional method, the temperature is 180 to 220°C. For example, in Japanese Patent Application Laid-Open No. 58-60012, a temperature of 150 to 210°C is adopted. In the present invention, the temperature is 180 to 230 by contact heating.
℃, and a temperature of 200 to 240℃ by non-contact heating is also used, but in order to obtain a drawn yarn with higher strength and elongation and higher dimensional stability, it is better to set the temperature of the yarn heating element to a higher temperature. Preferably, the temperature is 230 to 255°C for contact heating, and 240 to 275°C for non-contact heating. When the temperature of the yarn heating element is raised by contact heating, tar from the finishing agent applied to the yarn tends to accumulate on the yarn heating element. Therefore, it is preferable to employ non-contact heating. A preferred example for implementing the method of the present invention will be described with reference to the accompanying drawings. Although FIG. 1 shows the spinning process, FIG. 2 shows the stretching process in one-stage stretching, and FIG. 3 shows the stretching process in two-stage stretching, the present invention is not limited to these examples. In FIG. 1, molten polyhexamethylene adipamide is discharged from a spindle 1 having a large number of pores, passes through an atmosphere in which the temperature near the yarn is adjusted by a heating cylinder 2 installed directly below the spindle, Next, it is cooled and solidified by the cold air blown out at a constant speed from the cold air chamber 3, set by the steam 4 blown into the steam conditioner 5, applied with a finishing agent by the oiling roll 6, and then taken up by the take-up roll 7 and passed through the winder. At 8, the yarn is wound up as an undrawn yarn package 9. Undrawn yarn package 9 wound in this way
is supplied to a drawing heat treatment apparatus as a raw yarn for the drawing process shown in FIG. The yarn unwound from the undrawn yarn package is fed to a feed roll 10 and stretched by several percent between it and a first drawing roll 11. A thread heating element 12 is installed between the first drawing roll 11 and the second drawing roll 13, and the thread is hot drawn between the first drawing roll 11 and the second drawing roll 13 and wound up as a drawn yarn 14. . Further, the undrawn package 9 is similarly supplied to the drawing heat treatment apparatus as a raw yarn for the drawing step shown in FIG. The yarn unwound from the undrawn yarn package 9 is supplied to the feed roll 10, where it is stretched by several percent with the first drawing roll 11, between the first drawing roll 11 and the second drawing roll 13, and between the first drawing roll 11 and the second drawing roll 13. Thread heating bodies 12 and 15 are installed between the second drawing roll 13 and the third drawing roll 16, respectively, and the threads are spread between the first drawing roll and the second drawing roll, and between the second drawing roll and the third drawing roll. Two-stage hot stretching is carried out.
The drawn yarn 14 is wound up. Further, relaxation heat treatment of 15% or less can also be performed between the second stretching roll and the third stretching roll shown in FIG. FIG. 4 is a cross-sectional view of the non-contact heater, in which the yarn is heated while running in a yarn groove 18 surrounded by a heater 17 and a heat insulating material 19. The polyhexamethylene adipamide fibers obtained by the above method have excellent strength and elongation, dimensional stability, and fatigue resistance, and are useful as industrial materials such as tire cord belts. (g) Examples Next, the method of the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples. In the Examples, the relative viscosity of formic acid is the relative viscosity at 25° C. of a solution prepared by dissolving a polymer in 90% formic acid at a concentration of 8.4% by weight. Strong elongation is 20℃,
The sample was conditioned for 24 hours in a temperature and humidity controlled room at 65% RH and twisted at 80 turns/m using Shimadzu Autograph S-100.
This value was determined using a yarn length of 25 m, a descending speed of 30 cm/min, and a chart speed of 60 cm/min. The dry heat shrinkage rate was measured by applying a load (initial load) equivalent to 1/20 of the denier to a sample that had been conditioned for 24 hours in a temperature and humidity controlled room at 20℃ and 65%RH.
The length was determined by allowing a 1.0 m long yarn to shrink freely in an air oven at 160°C for 30 minutes, conditioning it in the above room for 4 hours, applying a load equivalent to the initial load, and measuring the length. Example 1 50 of hexamethylene diammonium adipate
% aqueous solution at a rate of 2000 parts/hour, and after concentrating to 70% in a concentration tank, the temperature was raised from 220℃ to 250℃ in 1.5 hours while maintaining a pressure of 17.5Kg/cm ² in the first reactor. Ta. The temperature was then increased to 280°C in the second reactor.
The pressure was returned to normal pressure while increasing the temperature to . After separating water vapor in the gas-liquid separation tank, the temperature is 350mmHg and 280℃ in the post-polymerization vessel.
After polymerization for 15 minutes, the yarn was guided to a spinning spin head via piping and spun out from a spinneret having 624 holes of 0.27 mmφ at 298° C. The formic acid relative viscosity of the spun yarn was 65. After immediately cooling and steaming, a spinning oil was applied as shown in Table 1. After being rotated around a take-up roll rotating at the take-up speed, it was wound up at the same speed as the take-up speed. Next, the undrawn yarn is passed between a feed roll at room temperature and a first drawing roll at room temperature.
%, and then stretched between a first stretching roll and a second stretching roll at room temperature at the stretching ratio shown in Table 1. At that time, a hot plate of 238° C. and 250 m/m was installed between the first stretching roll and the second stretching roll. The stretching speed is 15m/second stretching roll circumferential speed.
It's a minute. The stretching ratio is the maximum stretching ratio that does not cause yarn breakage for 15 minutes. Table 1 shows the physical properties of the drawn yarn obtained here. In the table, "intermediate elongation" is the elongation at a stress of 5.3 g/d, and "dimensional stability" is the sum of the intermediate elongation and the dry heat shrinkage rate. First twisting of the 1890d yarn obtained as described above
32.0T/10cm, further twist 32.0T/10cm,
Two threads are combined to form a raw cord, and using a Ritzler computer treater, the first zone is
160℃, tension 2.0Kg/cord, time 140 seconds, second zone temperature 230℃, tension 3.8Kg/cord, time 40
Second, the third zone was subjected to dip treatment with a resorcinol/formalin latex solution at a temperature of 230°C, a tension of 2.6 kg/cord, and a time of 40 seconds. The amount of adhesive adhered was 4.5%. The physical properties of this dip cord are shown in Table 2. In the table, the intermediate elongation is the elongation at a stress of 2.65 g/d. Fatigue resistance is JISL
-1017, a tube fatigue test using the Gutdeyer method was conducted according to the 3.2.2.1A method. Tube shape Inner diameter 12.5mm Outer diameter 26mm Length 230mm Bending angle 90° Internal pressure 3.5Kg/cm ² G Rotation speed 850rpm A fatigue test was conducted under the above conditions to measure the time until the tube bursts. It can be seen that it has excellent dimensional stability and fatigue resistance when the spinning speed is 1000 m/min or higher.
Furthermore, as the spinning speed increases, the dimensional stability and fatigue resistance improve, but the strength decreases.

【table】

【table】

[Table] Example 2 In Example 1, the spinning speed was 1500 m/min,
An undrawn yarn produced under the same conditions as 3000 m/min was used in the same manner as in Example 1, only the drawing speed was set to the conditions shown in Table 3 to obtain a drawn yarn.
A dip cord was obtained using these drawn yarns in the same manner as in Example 1. The results are shown in Tables 3 to 6. When the stretching speed exceeds 100 m/min, a decrease in strength, elongation, dimensional stability, and fatigue resistance is observed. Comparative Example 1 In Example 1, the spinning speed was 1500 m/min,
3000 m/min, and the undrawn yarn produced under the same conditions was taken over by the first Nelson roller, and then guided to the second to fourth Nelson rollers, which rotated at higher peripheral speeds, and subjected to drawing heat in three stages. It was set and wound at a speed of 1500 m/min. 1st~
Letting each godet roll group constituting the fourth Nelson roller be _G1 to _G4 , the temperature of each roll was _G1 : room temperature, _G2 : 80°C, _G3 : 220°C, and _G4 : 230°C.
The circumferential speed ratio of each roll is _G2 / _G1 =1.01, _G3 / _G2 =variable, _G4 / _G3 =1.6, and winding speed/ _G4 =0.95.
These drawn yarns were treated in the same manner as in Example 1 to obtain dip cords. The results are also listed in Tables 3 to 6. Compared to Example 2, a decrease in strength, dimensional stability, and fatigue resistance is observed.

【table】

【table】

【table】

【table】

[Table] Comparative Example 2 The undrawn yarn obtained in Example 1, No. 1 was drawn in the same manner as in Example 1, except that the drawing speed was set at 500 m/min. The stretching ratio is 5.7, and the physical properties of the drawn yarn are strength 9.8g/d, elongation 16.2%, and dimensional stability 15.7%.
It was hot. A dip cord was obtained from this drawn yarn in the same manner as in Example 1. The physical property of deep cord is strength.
It had an elongation of 8.0g/d, an elongation of 20.5%, a dimensional stability of 13.8%, and a GY fatigue life of 450 minutes. Comparing the above data with that of Example 1, No. 1, when the spinning speed is low (500 m/min), the strength, elongation, dimensional stability, and fatigue resistance are slightly lower when the drawing speed is lowered. It can be seen that it only improves. Example 3 Using the undrawn yarn used in Example 2 at a spinning speed of 1500 m/min, a drawn yarn was obtained using the stretching method of Example 1, with only the heater temperature set to the conditions shown in Table 7. A dip cord was obtained using these drawn yarns in the same manner as in Example 1. The results are shown in Table 8. It can be seen that the higher the stretching temperature, the better the stretchability and the dimensional stability.

【table】

[Table] Example 4 Using the undrawn yarn at the spinning speed of 1400 m/min used in Example 2, the drawing method shown in Fig. 4 was carried out between the first drawing roll and the second drawing roll in the drawing method of Example 1. A heater 17 was provided which had thread grooves 18 on its surface and was kept warm by a heat insulating material 19 including the surface. The length of the heater was 500 mm, and the yarn was allowed to run in the heater groove without contacting the heater. Set the heater temperature to the conditions shown in Table 9,
A drawn yarn was obtained. A dip cord was obtained using these drawn yarns in the same manner as in Example 1. The results are shown in Table 10. It can be seen that non-contact heating raises the temperature more and improves stretchability.

【table】

[Table] Example 5 Chips with formic acid relative viscosity shown in Table 11 were melted in an extruder, spun at 305°C from a spinneret having 624 holes of 0.25 mmφ, and heated to 350°C.
The material was passed through a heating cylinder of 1.0 mm in diameter, cooled, steamed, and a post-spinning oil was applied thereto, and then rotated around a take-up roll rotating at a take-up speed of 1400 m/min, and then wound at a speed equal to the take-up speed. Next, the undrawn yarn was stretched by 1% between a feed roll at room temperature and a first stretching roll at 105°C, and then stretched at a stretching ratio shown in Table 11 between the first stretching roll and second stretching roll. Stretched. Furthermore, the temperature of the second stretching roll is 220°C.
It is. At that time, a 240° C., 250 mm contact type hot plate was installed between the first stretching roll and the second stretching roll. The stretching speed is 12 m/min. Table 11 shows the physical properties of the drawn yarn obtained here. A dip cord was obtained using these drawn yarns in the same manner as in Example 1.
The results are shown in Table 12.

【table】

【table】

[Table] It can be seen that fatigue resistance improves as the viscosity increases, but the ultimate strength is almost saturated at a relative viscosity of formic acid of 80 to 90. Example 2 The undrawn yarn used in Example 5 was taken up by the first Nelson roller, then guided to the second to fourth Nelson rollers that rotate at higher peripheral speeds, and subjected to drawing heat in three stages. Perform the set,
It was wound at a speed of 1500 m/min. Each godet roller set constituting the 1st to 4th Nelson rollers
If G ₁ to _{G 4} , the temperature of each roll is G ₁ : room temperature,
_G2 : 80°C, _G3 : 220°C, and _G4 : 230°C. The peripheral speed ratio of each roll is G ₂ /G ₁ = 1.01, G ₃ /G ₂ = variable,
G ₄ /G ₃ =1.6, winding speed/G ₄ =0.95. These drawn yarns were treated in the same manner as in Example 1 to obtain dip cords. The results are shown in Tables 13 and 14. Compared to Example 5, a decrease in strength, dimensional stability, and fatigue resistance is observed.

【table】

[Table] Example 6 Using the undrawn yarn used in Example 3, the undrawn yarn was stretched by 1% between a feed roll at room temperature and a first stretching roll at 90°C. Stretched by 2.0 times between a stretching roll and a second stretching roll,
After being stretched to 1.6 times between the second and third stretching rolls, it was wound up. The temperatures of the second and third stretching rolls are each 200°C, and a contact type hot plate of 235°C and 250 mm is installed between the first and second stretching rolls. A 250 mm contact type hot plate at 245° C. was installed between the three stretching rolls. The stretching speed is 20 m/min. The obtained drawn yarn has a strength of 9.4 g/d and an elongation of 16.0.
% intermediate elongation 7.5%, dry heat shrinkage 4.4%, dimensional stability
It is 11.1%. This was subjected to dip treatment in the same manner as in Example 1 to obtain a dip cord. The result is intensity 8.0
g/d, elongation 20.2%, intermediate elongation 8.2%, dry heat shrinkage rate 3.5
%, dimensional stability was 11.7%, and GY fatigue life was 980 minutes.

[Brief explanation of the drawing]

FIG. 1 is a typical melt spinning equipment layout diagram for producing the undrawn polyhexamethylene adipamide yarn of the present invention, FIG. 2 is a layout diagram of a drawing heat treatment equipment for one-stage stretching, and FIG. The figure is a layout diagram of a stretching heat treatment apparatus for two-stage stretching. FIG. 4 is a sectional view of the non-contact heater. 1... Spinneret, 2... Heating cylinder, 3... Cold air chamber,
4... Steam piping, 5... Steam conditioner, 6... Oiling roll, 7... Take-up roll, 8... Winder, 9... Undrawn yarn package,
10... Feed roll, 11... First stretching roll,
12... Yarn heating body, 13... Second drawing roll, 14
...drawn yarn package, 15...yarn heating element, 16...
Third stretching roll, 17... Heater, 18... Thread groove, 19... Heat insulating material.

Claims (1)

[Claims] 1 Formic acid Polyhexamethylene adipamide having a relative viscosity of 50 to 150 is melted and discharged from a spinneret, cooled and solidified, and then taken at a drawing speed of 1000 m/min or more,
A method for producing polyhexamethylene adipamide fiber, which comprises first winding the fiber at a speed of 6000 m/min or less, and then hot-drawing it at a drawing speed of 100 m/min or less.