JPH041095B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Technical Field The present invention relates to a method for producing polyhexamethylene adipamide twisted yarn. More specifically, the present invention relates to a method for producing twisted polyhexamethylene adipamide yarn having excellent fatigue resistance, dimensional stability, and strength 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 the durability of tires is necessary not only from the economic effect of extending the life of the tire but also from the viewpoint of improving stability, and tire cords are also required to have yarns with better fatigue resistance. 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, steel polyethylene terephthalate, rayon, etc. have been mainly used in the field of radial carcass where dimensional stability is required. Steel rayon has low strength per unit weight, which increases the amount of cord used per tire, which increases the weight of the tire.
This is causing costs to rise. 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, the excellent high strength and heat resistance of nylon 66 fiber,
There was a need to take advantage of fatigue resistance and further improve dimensional stability. (C) Purpose of the Invention The present inventor first developed a polyhexamethylene adipamide fiber obtained by high-speed spinning at a spinning speed of 1000 m/min or higher, and then stretched it at a drawing speed of 100 m/min or lower to increase the strength and elongation. It was discovered that dimensional stability and fatigue resistance could be significantly improved, and a patent was filed on the same date as the present patent application. As a result of further investigation, the present inventor found that compared to the case where a drawn yarn that had been spun at high speed and drawn at a constant speed was once wound up according to a conventional method and then twisted at a rate of 150 to 600 times/m, Immediately after high-speed spinning and constant-speed drawing, twisting is performed continuously at a rate of 150 to 600 times/m, and the twisted yarn is wound up to improve the ratio of the strength of the twisted yarn to that of the original drawn yarn. , that is,
The present invention was achieved by discovering that the yarn strength utilization rate was improved. Therefore, an object of the present invention is to provide a twisted yarn having improved strength and elongation, dimensional stability, and fatigue resistance, particularly a twisted yarn having a high twist strength utilization rate. (d) Structure of the Invention The method for producing the polyhexamethylene adipamide twisted yarn 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. After that, the withdrawal speed is 1000
Once wound up at a speed of m/min or more, then stretched at a speed of 50
Hot-stretched at a speed of m/min or less, immediately and continuously
This is a method for producing polyhexamethylene adipamide twisted yarn, which is characterized by twisting the yarn at a rate of 150 to 600 times/m and winding it up as a twisted yarn. (E) Effects of the Invention The high-strength polyhexamethylene adipamide twisted yarn obtained by the present invention has excellent strength and elongation, dimensional stability, and fatigue resistance, and is suitable for tire cord materials and belts. It can be used as a material for (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 above polyhexamethylene adipamide contains
Commonly used additives, such as copper compounds such as copper acetate, copper chloride, copper iodide, 2-mercaptobenzimidazole copper complex salts, etc.
Heat stabilizers such as di-t-butyl-4-hydroxyphenyl)-propionate]-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 twisted yarn is significantly reduced. If the relative viscosity of formic acid exceeds 150, the drawability will not improve, making it impossible to obtain a twisted yarn having sufficient strength, and the dimensional stability will also decrease. The preferred formic acid relative viscosity of polyhexamethylene adipamide is 60-100. The polymer dried to a moisture content of 0.1% or less is spun using an extruder-type spinning machine, or the polymer in a molten state after completion of continuous polymerization is guided through a pipe to a spin head and spun directly. 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 by a take-up roller, and then wound up.
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 improvement in fatigue resistance and dimensional stability of the twisted yarn obtained is small. 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 polyhexamethylene adipate fiber is spun at a spinning speed of about 600 m/min to 4000 m/min, the wound yarn absorbs moisture and stretches, 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 it 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 may not come out from the winding machine due to shrinkage of the yarn, and the end surface of the winding cheese may become high, especially in this case. This tendency becomes more 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 biflex curvature of the highly oriented polyhexamethylene adipate undrawn yarn before drawing in the method of the present invention is 20×
It is preferably ^30-3 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 ,
Even if the stretching method is devised as in the present invention, the development of strength is insufficient. More preferably, it is 25×10 ⁻³ to 45×10 ⁻³ . The birefringence index can be measured using a Berek compensator attached to a polarizing microscope, and in the present invention, it is a value measured at 25° C. using an Olympus POM model and using olive oil as an immersion liquid. The method of the present invention is based on the premise that the winding process and the stretching and twisting process are separated. 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. The final stretching roll speed in the method of the present invention is 50 m/
It must be less than 1 minute. If the twisting speed exceeds 50 m/min, not only will the strength and elongation of the drawn yarn before twisting be insufficient, but the spindle rotation speed for twisting, which is equivalent to 150 to 600 times/m, will be excessive.
The strength of the twisted yarn is reduced. Physically, there are no disadvantages due to the drawing speed being too low, but the productivity is significantly reduced. The stretching speed that can be practically adopted is 5.
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 actively driven rolls, a combination of actively driven rolls and a free roll, or a roll used for stretching multi-filament yarns such as fabrics and monofilaments. A roll unit combining five to nine actively driven rolls can be used as shown in FIG. It is preferable to provide a feed roll before 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. Also, other tensioning devices such as tensors may be used. 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 on the Nelson roll unit or the combination of actively driven rolls and free rolls is 2 times or more.
Seven times are used. Mirror surface requires fewer times,
The roughness of the satin finish increases as the roughness increases. Although a number of turns of 7 or more is also adopted, 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 stretching rolls to carry out heating and stretching. 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. For contact heating
If the temperature is lower than 180°C, sufficient stretching will not take place, and if the temperature exceeds 260°C, the yarn will melt. 200 for non-contact heating
If the temperature is lower than 280°C, sufficient stretching will not be carried out, 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,
JP-A-58-60012 adopts a temperature of 150 to 210°C. In the present invention, temperatures of 180 to 230°C for contact heating and 200 to 240°C for non-contact heating are also used, but in order to obtain drawn yarn with higher strength and elongation and higher dimensional stability, it is necessary to It is better to make the temperature higher. 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. One of the major features of the method of the present invention is that both the stretching and twisting steps are performed as one continuous step, in contrast to conventional methods in which the stretching step and the twisting step were separated. By immediately following the drawing process and twisting at a rate of 150 to 600 times/m according to the method of the present invention, it is possible to improve the twist strength utilization rate. The number of twists is usually determined in order to improve fatigue resistance by designing the characteristics of the tire. for example,
Approximately 300 to 350 times/m for 1890d yarn, 1260d
In the case of yarn of 840 d, about 350 to 450 turns/m, and in the case of 840 d yarn, about 450 to 550 turns/m.
In the case of the highly fatigue-resistant yarn obtained by the method of the present invention, it can be twisted in the above-mentioned twist number range commonly used and used as a highly fatigue-resistant twisted yarn, but the number of twists can be reduced and the processed cord It can be used with improved strength, modulus, and dimensional stability. A preferred example for implementing the method of the present invention will be described with reference to the accompanying drawings. Although the spinning process is shown in FIG. 1 and the stretching and twisting process is shown in FIG. 2, the present invention is not limited to this example. 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 twisting device as a raw yarn for the drawing and twisting process shown in FIG. The yarn unwound from the undrawn yarn package is fed to a feed roll 12 and stretched by several percent in the direction of the first stretching roll 13. A yarn heating body 15 is installed between the first drawing roll 13 and the second drawing roll 16, and the yarn is hot drawn between the first drawing roll 13 and the second drawing roll 16. Become. Stretched yarn 1
0 is feed rolls 17, 19 and press roll 18
The bobbin 21 is wound around the bobbin 21 and sent to the twisting section at a constant speed, and is inserted into the spindle via the ring 21 with sliding travel.
It is wound up as a pre-twisted thread 23 which is twisted 150 to 600 times/m. Reference numeral 14 indicates a drawing pin, and reference numerals 11 and 20 indicate yarn guides, which are used as appropriate if necessary. FIGS. 3 and 4 schematically show examples of apparatus for carrying out typical stretching and twisting steps, respectively, according to conventional methods. The spun and wound unstretched package 9' is supplied to a stretching heat treatment apparatus as a raw yarn for the stretching process shown in FIG. 3, and after passing through a yarn guide 11', is supplied to a feed roll 12'.
A stretch of several percent is applied between the first stretching roll 13' and the first stretching roll 13'. A thread heating element 15' is installed between the first drawing roll 13' and the second drawing roll 16', and the thread is heated between the first drawing roll 13' and the second drawing roll 16'.
6' to form a drawn yarn 10', which is wound up as a pirn 24'. As shown in FIG. 4, the drawn yarn 24' is wound and held around the feed rolls 17', 19' and the press roll 18', and sent out at a constant speed to the twisting section, where it is passed through a ring 24 with a sliding traveler. The yarn is twisted 150 to 600 times/m and then wound onto a bobbin 21' which is inserted into a spindle as a pre-twisted thread 23'. 11'', 11 and 20' are yarn guides. The twisted yarn of the present invention can be used as a ply-twisted yarn having excellent strength and elongation, dimensional stability, and fatigue resistance. After that, it is woven, subjected to adhesive heat treatment, and then used as a rubber reinforcing material for tire cords and belts. The invention is not limited to these examples. In the examples, "formic acid relative viscosity" is the relative viscosity at 25°C of a solution of 90% formic acid dissolved at a polymer concentration of 8.4% by weight. . "Strong elongation"
Samples were conditioned for 24 hours in a temperature and humidity controlled room at 20℃ and 65% RH using a Shimadzu Autograph S-100, with a yarn length of 25cm, a descending speed of 30m/min, and a chart speed. This value was determined at 60cm/min. "Intermediate elongation" is the elongation at a stress of 2.65% when measured under the same conditions. "Dry heat shrinkage rate" is measured by applying a load (initial load) equivalent to 1/20 of the denier to a sample that has 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. "Dimensional stability" is the sum of intermediate elongation and dry heat shrinkage. "Fatigue resistance" is JISL-
A tube fatigue test using the Gutdeyer method was conducted according to the 10173.2.2.1A method. Tube shape Inner diameter 12.5 mm Outer diameter 26 mm Length 230 mm Bending angle 90° Internal pressure 3.5 Kg/cm ² G Rotation speed 850 rpm A fatigue test was conducted under the above conditions and the time until the tube burst was measured. 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 a gas-liquid separation tank, it is heated at 350mmHg and 280℃ in a post-polymerization vessel.
After polymerization for 15 minutes, the yarn was guided to a spinning spin head via piping and spun 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 being immediately cooled and steamed, a spinning oil was applied thereto, the material was rotated around a take-up roll rotating at the take-up speed shown in Table 1, and then wound at a speed constant with the take-up speed. Next, the undrawn yarn is stretched by 1% between a feed roll at room temperature and a first stretching roll at room temperature, and then stretched at a stretching ratio shown in Table 1 between the first stretching roll and a second stretching roll at room temperature. After stretching, the material was twisted at a rate of 320 times/m and wound. 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 was 15 m/min at the circumferential speed of the second stretching roll. The stretching ratio is the maximum stretching ratio that does not cause yarn breakage for 15 minutes. The physical properties of the twisted yarn obtained here are shown in Table 1.

[Table] Two more twisted yarns obtained as described above were twisted and twisted at a rate of 320 times/m to form a raw cord.
Table 1 shows the physical properties of the raw cord. The raw cord was processed using a Ritzler computer treater, the temperature of the first zone was 160℃, the tension was 2.0Kg/cord, and the time was 140℃.
Second zone temperature 230℃, tension 3.8Kg/cord, time 40 seconds, third zone temperature 230℃, tension 2.6
Adhesive treatment was performed using resorcinol/formalin latex solution at kg/cord for 40 seconds. The amount of adhesive adhered was 4.5%. The physical properties of this dip cord are shown in Table 2. It can be seen that it has excellent dimensional stability and fatigue resistance when the spinning speed is 1000 m/min or higher. Also,
The higher the spinning speed, the better the dimensional stability and fatigue resistance, but the lower the strength.

[Table] Comparative Example 1 The undrawn yarn obtained in Example 1 was transferred by 1% between the feed roll at room temperature and the first drawing roll at room temperature.
After stretching, the first stretching roll and the second stretching roll at room temperature are
The film was stretched between stretching rolls at the stretching ratio shown in Table 1 and wound up. 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 the peripheral speed of the second stretching roll.
The speed is 15m/min. The stretching ratio is the maximum stretching ratio that does not cause yarn breakage for 15 minutes. 1890d obtained as described above
The original yarn was twisted at a rate of 320 times/m. Table 3 shows the physical properties of the obtained ply-twisted yarn. Two more pre-twisted yarns obtained as described above were twisted and twisted at a rate of 320 times/m to obtain a raw cord.
Table 3 shows the physical properties of the raw cord. The raw cord was processed in the same manner as in Example 1 to obtain a dip cord. The results are shown in Table 4.

【table】

[Table] Compared to the comparative examples, the examples are superior in both strength and elongation, and are comparable in dimensional stability and fatigue resistance. Example 2 In Example 1, the spinning speed was 1500 m/min and 3000 m/min.
m/min, and undrawn yarn produced under the same conditions as above was followed by the same stretching and twisting method of Example 1, only the stretching speed was set to the conditions shown in Table 5, to obtain a first twisted yarn. These pre-twisted yarns were made into a raw cord in the same manner as in Example 1.
I got the dip code. The results are shown in Tables 5 and 6.

【table】

【table】

[Table] Example 3 Using the undrawn yarn with a spinning speed of 1500 m/min used in Example 2, the drawing and twisting method of Example 1 was used, only the heater temperature was set to the conditions shown in Table 7, and the first twisted yarn was Obtained. A raw cord dip cord was obtained using these ply-twisted yarns in the same manner as in Example 1. The results are shown in Tables 7 and 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 stretching and twisting method of Example 1 was carried out using the undrawn yarn between the first drawing roll and the second drawing roll. The heater surface shown in Fig. 5 has thread grooves 26,
Heater 25 whose surface is kept warm by heat insulating material 27
has been established. The length of the heater was 500 mm, and the yarn was allowed to run in the heater groove without contacting the heater. The heater temperature was set to the conditions shown in Table 9, and a plied yarn was obtained. A raw cord dip cord was obtained using these ply-twisted yarns in the same manner as in Example 1. The results are shown in Tables 9 and 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 2.0 mm in diameter to cool it, and after steaming, a spinning oil was applied thereto, and after being rotated around a take-up roll rotating at a take-up speed of 1400 m/min, it was wound up 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 the stretching ratio shown in Table 11 between the first stretching roll and second stretching roll. and stretched. After twisting at a rate of 320 times/m, the material was rolled up. Note that the temperature of the second stretching roll was 220°C. 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. The physical properties of the first twisted yarn obtained here are shown in Table 11. A raw cord dip cord was obtained using these ply-twisted yarns in the same manner as in Example 1. The results are shown in Tables 11 and 12.

【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. Comparative Example 2 The undrawn yarn used in Example 5 was used, and the undrawn yarn was taken up by the first Nelson roller, and then guided to the second to fourth Nelson rollers that rotate at higher circumferential speeds, and then passed through three stages. Stretching heat setting was performed separately and the film was wound at a speed of 1500 m/min. 1st
−If each godet roller set making up the fourth Nelson roller is G ₁ to G ₄ , the temperature of each roll is
_G1 : room temperature, _G2 : 80°C, _G3 : 220°C, and _C4 : 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 Comparative Example 1 to obtain dip cords. The results are shown in Table 13.

[Table] Compared to Example 5, the comparative example in which highly oriented yarn was drawn at a conventional speed shows a decrease in dip cord strength, dimensional stability, and fatigue resistance. Example 6 Using the undrawn yarn obtained in Example 1 at a spinning speed of 1500 m/min, the stretching and twisting method of Example 1 was carried out.
Only the number of twists was set to the conditions shown in Table 14 to obtain a first twisted yarn. A raw cord and a dip cord were obtained from these plied yarns in the same manner as in Example 1. Results 14th and 15th
Shown in the table. When the number of twists is lowered, elongation and fatigue resistance decrease, but strength, intermediate elongation, dry heat shrinkage rate, and dimensional stability are improved.

【table】

[Table] Example 7 Formic acid chips with a relative viscosity of 65 were melted in an extruder, spun at 305°C from a spinneret having 420 holes of 0.21 mmφ, cooled, and after steaming, a spinning oil was applied. , after being rotated around a take-up roll rotating at a take-up speed of 1400 m/min, and then wound up at a speed equal to the take-up speed. Next, the undrawn yarn is stretched by 1% between a feed roll at room temperature and a first stretching roll at 90°C, and then stretched by a factor of 2.0 between the first stretching roll and a second stretching roll. After being stretched 1.6 times between the stretching roll and the third stretching roll
The material was twisted at a rate of 490 times/m and wound. a second stretching roll;
The temperature of each third stretching roll is 200°C,
235℃ between the first stretching roll and the second stretching roll,
A 250mm contact type hot plate is installed, and a temperature of 250mm at 245℃ is installed between the second and third stretching rolls.
A contact type hot plate was installed. The stretching speed is
It was 20m/min. The strength of the obtained pre-twisted cord is
The elongation was 8.8 g/d and 20.6%. A dip cord was obtained in the same manner as in Example 1. The results are strength 8.1g/d, elongation 20.8%, intermediate elongation 8.1%, dry heat shrinkage rate 3.5%, dimensional stability 11.6%, and GY fatigue life.
It was 980 minutes.

[Brief explanation of drawings]

Figure 1 is a diagram of a typical melt-spinning apparatus for producing the polyhexamethylene adipamide undrawn yarn of the present invention, Figure 2 is a layout diagram of a drawing heat treatment and twisting apparatus, and Figure 3 is a drawing of a drawing heat treatment and twisting apparatus. FIG. 4 is a layout diagram of a heat treatment device, FIG. 4 is a layout diagram of a twisting device, and FIG. 5 is a sectional view of a non-contact heater. 1... Spinneret, 2... Heating tube, 3... Cold air chamber, 4... Steam piping, 5... Steam conditioner, 6... Oiling roll, 7...
Take-up roll, 8... Winder, 9,9'...
...undrawn yarn package, 10, 10'... drawn yarn, 11, 11'', 11... yarn guide, 12,
12'...Feed roll, 13,13'...1st
Stretching roll, 14, 14'... Stretching pin, 15,
15'... Yarn heating body, 16, 16'... Second drawing roll, 17, 17'... Feeding roll, 18, 1
8'...press roll, 19,19'...feed roll, 20,20'...thread guide, 21,21'...
Ring, 22, 22'...Bobbin, 23, 23'...
... Lower twisted thread, 24'... Drawing pirn, 25... Heater, 26... Yarn groove, 27... 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, then wound up at a take-up speed of 1000 m/min or more, and then stretched at a drawing speed of 50 m/min or less. 1. A method for producing twisted polyhexamethylene adipamide yarn, which comprises hot stretching at a speed of 150 to 600 times/m, immediately and continuously twisting the yarn at a rate of 150 to 600 times/m, and winding the twisted yarn.