JPS63159516A - Production of polycapramide fiber - Google Patents

Abstract

PURPOSE:To stably and efficiently obtain a polycapramide fiber having high strength, good dimensional stability and fatigue resistance, by spinning, drawing and vulcanizing a polycapramide having high polymerization degree in specific condition. CONSTITUTION:A highly polymerized polycapramide having at least >=95mol% epsilon-capramide unit and >=3.0 relative viscosity in sulfuric acid is spun from a spinneret 2 in a melt state and cooled and solidified in a pressure spinning cylinder 11 kept in >=1kg/cm<2> higher pressure than atmospheric pressure. A polymer amount per pore of the spinneret is 2.5g/min and the winding speed is >=1,500m/min and the double refractive index of the wound fiber is >=2X10<-3>. A heating cylinder 3 is provided directly under the spinneret and atmospheric temperature in an area of >=10cm is +30 deg.C higher than a melting point of the polyamide and pressure fluid is blown from a device 5 for blowing a circular cool wind. The resultant spun filament is drawn in maximum draw power of >=90% and total draw power of 1.2-3.5 times by a thermal drawing method having two or more stages.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a high-strength polycapramide fiber, which exhibits high strength and improved strength after vulcanization, especially when used as a rubber reinforcing material for tire cords and belts. The present invention relates to a method for stably and efficiently producing polycapramide fibers having dimensional stability and fatigue resistance.

[Conventional technology]

Polycapramide fibers have excellent properties such as high strength, heat resistance, fatigue resistance, and adhesion to rubber, so they are used as cord materials for rubber reinforcement, such as tire cords, conveyor belts, power transmission belts, seat belts, and sewing thread. It is widely used for fishing nets, various cover sheets, etc.

However, tire cords made of polycapramide fibers are generally vulcanized at high temperatures of 150'C or higher during the tire vulcanization process, and when taken out of the vulcanizer immediately after vulcanization, they contract rapidly and lose strength. There is a disadvantage that it occurs. Polycapramide fibers have a high shrinkage rate, so they undergo rapid shrinkage during the vulcanization process, and this shrinkage causes major changes in the fiber structure.
It is strongly reduced.

Therefore, in order to suppress the decrease in strength during the vulcanization process, it is necessary to reduce the heat shrinkage rate of polycapramide fibers, that is, to improve the dimensional stability, and to create a stable structure that does not cause a significant decrease in strength even if the shrinkage occurs. It is necessary to have a fiber structure that is flexible.

Improvements in the dimensional stability of polycapramide fibers, fibers with improved dimensional stability and reduced strength during vulcanization, and methods for producing the same are disclosed in JP-A-57-191337 and JP-A-Sho. This method has been proposed in Japanese Patent No. 58-54018 and the like. In addition, examples of technologies that have achieved high strength of 10 g/d or more by pursuing higher strength of polycapramide mats include JP-A-58-98415 and JP-A-58-13.
Many proposals have been made, including Publication No. 6823.

The above-mentioned Japanese Patent Application Laid-Open No. 67-19337 discloses that polycapramide fibers having a relative viscosity of 3.0 or more are used at a rate of 2000 to 4500 m/r.
This disclosure discloses a method of high-speed spinning at a speed of f1 inch, stretching the obtained undrawn yarn at a maximum draw ratio of at least 85% or more, and then twisting the yarn to obtain a rubber reinforcing cord. This method improves dimensional stability and strength loss during vulcanization of polycapramide fibers! fiber is obtained.

However, the strength of this fiber is at most 8.5 g/d, which is rather lower than that of conventional industrial fibers. Therefore, although the strength utilization rate in the subsequent tire cord processing step and the decrease in strength during vulcanization have been improved, the absolute value of the strength of the vulcanized cord has not reached a satisfactory level. For example, according to FIG. 2 related to the embodiment of this patent application, the cutting strength of the cord when vulcanized at 160°C is 55% higher than that of conventional fibers.
The improvement is only about 10%. Furthermore, JP-A-58-54018 proposes a polycapramide fiber with a low shrinkage rate and excellent fatigue resistance, and a method for producing the same, but the strength of the polycapramide fiber is 9°1 as mentioned above.
g/d or less, and although the strength utilization rate in the tire cord processing process has been improved, the absolute value of the tire coat (processed cord) strength is rather lower than that of conventional cords.

In other words, although both technologies have attempted to improve the useful properties of tire cords, such as dimensional stability, decrease in strength during vulcanization, and fatigue resistance, the strength of the yarn itself is low, so the strength of the cord after vulcanization cannot be improved. This is insufficient in terms of obtaining a tire cord with a high absolute value.

On the other hand, JP-A-58-98415, JP-A-58-1368
Publication No. 23 pursues high fiber strength and achieves 10 g/d or more by low-speed spinning and a special drawing process, but the fibers obtained by such methods do not have sufficient dimensional stability. The strength after vulcanization is by no means high.

Therefore, the object of the present invention is to provide polycapramide II which has high strength after vulcanization, improved dimensional stability, and fatigue resistance when used as a rubber reinforcing material in tire cords, belts, etc.
The object of the present invention is to provide a method for stably and efficiently producing I.

[Means for solving problems]

In a method for producing polycapramide fibers by melt spinning and drawing a polycapramide comprising at least 95 mol% or more of ε-capramide units and having a high degree of polymerization with a sulfuric acid relative viscosity of 3.0 or more, (1) the melt polymer is The material is spun from a spinneret, guided into a pressurized spinning tube installed directly below the spinneret and held at a pressure 1 kg/cm' higher than the outside air pressure, cooled and solidified, and then sealed from the lower end of the pressurized spinneret. passing it through a nozzle and leading it to the outside air normal pressure area and taking it away;
(2) In the above method, at least one
A heated tube is installed so that the atmosphere of 0 cm or more has a temperature of 30° C. or more above the melting point of the polyamide, and the spun yarn passes through the high temperature atmosphere and then through the enclosed area, and then (3) The amount of polymer per hole of the spinneret is 2.5 g/min.
(4) The birefringence of the above-mentioned drawn yarn is 20X10-3 or more; In addition, the stretching is carried out at a total stretching ratio of 1.2 times or more and 3.5 times or less.

[Effect]

The method of the present invention proposes a special method as described below. That is, the method of the present invention is based on the high-speed spinning/drawing method disclosed in JP-A-58-54018, and is based on the high-speed spinning/drawing method disclosed in JP-A-60-1340.
11, the pressurized atmosphere spinning method proposed in JP-A No. 60-134015, and the conventional method applied to the production of high-strength polycapramide fibers. This method was completed as a new method by making improvements to meet the purpose. To summarize, (1) we have reduced the amount of foreign matter mixed into the fibers and improved the uniformity of the fibers; (2) we have improved the yarn spun from the spindle during high-speed spinning;
By effectively utilizing the effects of the cooling delay zone and the quenching zone, and (3) by adopting a drawing method suitable for the undrawn yarn obtained by the above-mentioned high-speed spinning method, it is possible to We have completed a method to stably and efficiently produce high-strength yarn, which was not possible using other methods.

Next, the method for producing the fiber of the present invention will be explained in detail with reference to FIGS. 1 and 2.

More than 95 mol% of the polycapramide used in the present invention is ε-
It consists of capramide units and may contain less than 5 mol% of a copolymer component. Other amide-forming units that can be copolymerized include dicarboxylic acids such as adipic acid, sebacic acid, terephthalic acid, and isophthalic acid, and diamines such as tetramethylene diamine, hexamethylene diamine, metaxylylene diamine, and the like. Further, less than 5% by weight of polytetramethylene adipamide, polyhexamethylene adipamide, polyhexamethylene adipamide, poly xamethylene terephthalamide, and polyhexamethylene isophthalamide are blended into the above polycapramide. It can also happen. If the copolymerization component is 5 mol% or more and the blend polymer is 5% by weight or more, the desired dimensional stability and high strength after vulcanization cannot be achieved.

The polycapramide polymer of the present invention has a sulfuric acid relative viscosity of 3.0° or more, preferably 3.2 to 4.5.

@Acid relative viscosity here means polymer concentration of 1% by weight in sulfuric acid.
This is the relative viscosity of the dissolved solution measured at 25°C.

Also, the polycapramide of the present invention! Since III is mainly used for industrial materials such as rubber reinforcing materials, it is preferable to contain an antioxidant for the purpose of imparting sufficient durability against heat, light, oxygen, etc. Examples of antioxidants include copper compounds such as copper acetate, cupric chloride, and copper iodide; halogen compounds such as potassium iodide, potassium bromide, triethylbutylammonium iodide, and pentaiodobenzene;
N,N''-di-β-naphthyl-p-phenylenediamine, 2-mercapto\nsoimidazole, tetrakis-
[An organic antioxidant such as methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate-co-methane is used. Copper compound is 1100p as copper
p or less, particularly preferably 20 to 80 ppm. Although it uses less copper salt than conventional high-strength polycapramide fibers,
In this case, by using 0.02% by weight or more of the halogen compound in combination, the same level of heat resistance, light resistance, and oxidation resistance as conventional fibers can be maintained. Other antioxidants used in combination with the copper salt include the halogen compounds and/or other antioxidants, each of which is used in an amount of 0.02 to 0.6% by weight. The polycapramide polymer is dried to a moisture content of 0.1% by weight or less and then melt-spun, preferably using an extruder type spinning machine. Melting temperature is 270-310℃
is preferred.

Immediately before spinning the polymer from the spinneret (2), filtration is performed in the spinning bag (1) for the purpose of removing foreign substances in the molten polymer. Using a wire mesh with pores of 3μ or a sintered filter made of stainless uA fiber, foreign matter generated by the decomposition of the antioxidant containing the copper salt and foreign matter mixed into the polymer before spinning are removed, and then the spinning is performed. It is important to avoid contamination of foreign matter into the yarn as much as possible. The amount of foreign matter permissible in the polycapramide fibers of the present invention is, for example,
When an AT fiber sample was dissolved in a phenol/tetrachloroethane solution and measured using Leuco's "Old AC4100",
The number of foreign particles of 5 μ or more in 1 g of sample is less than 1000. Directly below the spinneret, a pressure spinning tube (11) is attached via a sealing member such as an O-ring and, if necessary, a heat insulating plate with a thickness of I't cm to 10 cm. The pressurized spinning tube of the present invention is composed of a heating tube (3), a pressurized cooling air blowing device (4), a yarn guide duct (6), a yarn outlet seal portion (7), and the like. In the pressurized spinning cylinder, an area of at least 10 cm or more from the spinneret surface contains the spun yarn (
In order to delay the cooling of Y), it is necessary to maintain the atmosphere at a temperature above the melting point of the polymer +30°C, preferably above 280°C and below 400°C.

Therefore, 5 cm or more, preferably 10 to 100 cm
Attach the heating tube (3) directly below the cap.

An annular cooling air blowing device (5) for blowing cold air from the outer periphery of the spun yarn is attached below the heating cylinder. The inside of the spinning cylinder can be pressurized to a high pressure state by introducing pressurized fluid from the annular cooling air blowing device (9). The yarn is then rapidly cooled by blowing in pressurized fluid.

As the pressurized fluid, air, nitrogen, water vapor, or other gas inert or active to the polymer can be used, but air is usually used. In order to obtain the effects of the present invention, the pressure inside the spinning cylinder is 1 kg/C11' or more, preferably 3 kg/C11' or more, than the outside air pressure.
It is necessary to set the pressure to a high pressure of kg/C1'.

The yarn outlet is sealed by a seal nozzle (7) that is opened to an extent that allows smooth passage of the yarn. Only a small amount of airflow accompanying the yarn leaked from the seal nozzle. It is necessary to provide a seal that prevents the yarn from shaking significantly due to the leakage of the airflow, and from causing entanglement between the yarns.

For example, the hole diameter of the seal nozzle is 3 to 2 times the cross-sectional area of the spun yarn.
0, preferably 5 to 10 times. Furthermore, in addition to the seal nozzle at the yarn outlet, an air blowing part (10) may be provided at a different position near the yarn outlet at the bottom of the yarn path duct.

The airflow blowing section blows out the fluid in the pressurized spinning tube when it becomes hot due to heat exchange with the spun yarn, but balances it with the pressurized airflow blown in from the annular cold air blowing device, Do this while maintaining the specified pressure. The discharge amount is relatively small, and the temperature inside the pressurized spinning cylinder does not rise by dissipating heat through the outer wall of the yarn guide duct or actively cooling the outer wall of the duct, and the yarn cannot be cooled sufficiently. The lower airflow outlet of the duct can be kept closed if the As mentioned above, one of the characteristics of the present invention method is that polycapramide polymer is spun from a spinneret, and after the molten yarn passes through a cooling delay zone, it is rapidly cooled and solidified by an annular cold air blowing device. The reason for this is as follows:).

Generally, in order to maintain the single filament fineness of high-speed spun/drawn fibers to be the same as that of conventional high-strength polyamide fibers, the discharge amount per spinneret hole must be increased. The single yarn fineness of a typical polycapramide fiber for tire cords is about 6 denier. As in the present invention, a high-speed spinning/drawing method consisting of a spinning speed of 1500 n/min or more is adopted, and the single fiber fineness of the drawn yarn is 3 denier or more, preferably 4 denier or more, so as not to become extremely small. More preferably, the amount of molten polymer discharged from the spinneret must be as high as at least 2.5 g/min in order to obtain a denier of about 6 denier, similar to conventional high-strength polyamide fibers. If a high-speed spinning/drawing method is adopted without increasing the discharge amount per die hole, and
Similar to the present invention, in order to take advantage of the production efficiency of the high-speed spinning/drawing method, it is necessary to increase the number of filaments per spinneret, but as a result, the filament spacing becomes narrow and collisions between filaments occur. Thread breakage occurs easily. In addition, since it becomes difficult for each filament to cool uniformly, the difference in physical properties between the filaments increases, resulting in some defects in tire cord performance, such as a decrease in fatigue resistance and adhesion. .

Generally, in high-speed spinning, the deformation rate is high before being spun and cooled and solidified. However, in the case of the highly polymerized polycapramide fiber of the present invention, which is characterized by spinnability that can follow such rapid deformation, the high speed In order to ensure stringiness during spinning, it is necessary to avoid rapidly cooling the molten spun yarn directly under the spinneret. Therefore, directly below the base, at least 10c
An atmosphere with a temperature of at least 30° C. above the melting point of polycapramide is applied to an area of 10 to 100 cm or more.

The yarn that has passed through the high-temperature atmosphere area directly below the cap is then rapidly cooled. During the cooling and solidification process of the molten polycapramide yarn, it is necessary to immediately pass through a temperature range where the crystallization rate is high, usually 120 to 210°C. In the high-speed spinning method of the present invention, it is solidified by cooling! Lli fibers are already in the process of oriented crystallization (or are in a precursor orientation state where bow-to-bow oriented crystallization occurs.If they remain in a temperature range where the crystallization rate is high for a long time, they will form large spheres in addition to oriented crystals. Crystalline crystals are formed.

If a large number of these spherulite crystals are produced, the yarn will not be sufficiently stretched in the subsequent drawing step, and a high strength yarn will not be obtained. The residence time in the temperature range where the crystallization rate is high is determined by the external cooling conditions, the speed of the yarn, the heat capacity of the yarn, the surface area of the filaments constituting the yarn, etc. As mentioned above, high speed spinning/
If you try to obtain a single yarn fineness of 3 denier or more by drawing, the discharge rate per spinneret hole will be as large as 3 g/min, so rapid cooling will not be possible, and many spherulites will be produced, resulting in a high-strength yarn. I couldn't. For this reason, in high-speed spinning/drawing methods, it was generally necessary to reduce the single yarn denier to solve the problem, but as mentioned above, there are other obstacles caused by reducing the single yarn denier, so high-speed spinning/drawing methods have no choice but to solve the problem. It has been desired to obtain a high strength polyamide fiber having a deep single filament fineness of at least 1 denier, preferably at least 4 denier, and more preferably at least about 6 denier.

The present invention is a high-strength polyamide that has a single yarn fineness of 3 denier or more by high-speed spinning! ! This paper proposes a method to obtain II.The key point is to delay cooling in a high-temperature atmosphere directly below the cap and to effectively perform rapid cooling directly under the high-temperature atmosphere zone. The method is to spin under a pressurized atmosphere with an electric current of at least 1 kg/ui', preferably at least 3 kg/ui' from the outside air, until the material is cooled and solidified.This method is adopted. By this method, polycapramide f!A fibers with good transparency and few spherulite crystals can be obtained.By pressurized atmosphere spinning, the air density is high in both the high temperature atmosphere zone and the quenching zone, which improves heat transfer and improves the spun yarn. A cooling delay followed by a rapid cooling are each effectively achieved.
Conventional uniflow type cooling devices, annular blowout type cooling devices, etc. cannot achieve this goal even by increasing the cooling air velocity, lowering the cooling air temperature, or lengthening the cooling zone. After the spun yarn leaves the pressurized spinning tube, it is applied with a lubricant by a lubricating device (12), its speed is controlled by a take-up roll (13), and it is once wound up by a winder (15). , or is rolled up after continuous rolling with the rolling roll (14). The oil supply device (12) may also be provided within the pressurized spinning cylinder (11). Normally, oil is supplied from the seal nozzle part,
It is also preferable to have the function of a so-called guide oil supply device. More preferably, a method is adopted in which a part of the oil is applied at the seal nozzle portion and further oil is added so that a predetermined amount of oil adheres after exiting the seal nozzle. The take-up speed (also called spinning speed) is 1500 m/min or more, preferably 200 m/min or more.
0-6000m/min delta. The birefringence of this drawn thread is 2
0x10" to 45x10"1. Pick up speed 150
When the birefringence is less than 0 m/min and the birefringence is less than 20XIO'', the dimensional stability of the subsequently spread fiber is poor, and the strength decreases greatly during vulcanization, and the effects of the present invention cannot be obtained. If the inside of the cylinder is pressurized to 1 kg/c?I!' or more than the outside air pressure, it is difficult to take off the spinning yarn stably.On the other hand, 45
If it exceeds ×lO"3, the desired high-strength polyamide fiber cannot be obtained even if the subsequent drawing method of the present invention is applied.

In addition, in the two-step method in which the spinning process and the drawing process are separated as shown in Figures 1 and 2, if the spinning speed is less than 3000 m/min, the polycapramide fiber will undergo longitudinal swelling and will not return to its normal state. I can only wind it. Therefore, when producing the fiber according to the present invention from an undrawn yarn at a speed of less than 3000 m/min, the spun yarn is taken off with a take-up roll (13), and then continuously stretched by less than 2 times. It is then wound up with the roll (14). At this time, it is preferable to leave the take-up roll unheated or to use a heating roll heated to 100°C or lower, and the stretching roll to 150°C or lower. It is preferable to select a stretching ratio as low as possible, which does not cause longitudinal swelling and allows normal winding, in order to prevent the above-mentioned longitudinal swelling.
It is sufficient if the angle is approximately equal to 0°3.

Next, the wound undrawn yarn (16) is drawn by the drawing method according to the present invention at a maximum drawing ratio of 90% or more. The maximum draw ratio herein refers to the highest draw ratio at which drawn fibers having a length of 500 m or more can be obtained.

Multi-stage hot stretching of two or more stages is preferred as the stretching method, and since the undrawn yarn according to the present invention has already achieved high orientation, the total stretching ratio is 3.5 times or less, usually 3.0. ~1.4
It is cultivation. Incidentally, the total stretching ratio refers to the total stretching ratio including the continuous stretching performed for the purpose of preventing longitudinal swelling after the above-mentioned spun yarn is taken up with a take-up roll.

The polycapramide fiber obtained by the method of the present invention has a residual elongation of 10 to 20%, and can be drawn at a higher magnification to a lower elongation than conventional polycapramide fibers. The polycapramide fiber of the present invention is a uniform fiber that contains only a small amount of decomposed foreign substances of antioxidants, and can be stably drawn to low elongation levels in combination with the special drawing method described below. Further, it is characterized in that the highly oriented fiber structure is maintained even after stretching.

An example of the stretching method of the present invention is shown in FIG. 2, and the details are as follows. The stretching rolls used in the present invention are a commonly used Nelson roll unit using two pairs of actively driven rolls, or a combination of four manually driven rolls and a free roll. 1.05 to 2.0 between FR (feet roll = 17) and IDR (first draw roll: 18), and 1.1 to 1.50.2 DR between IDR and 2DR (second draw roll: 19). Between 3DR (third draw roll: 20) is 1.05~1°50.3D
The distance between R and RR (tension adjustment roll: 21) is 0.90 to 1.
The stretching ratio is distributed so that it becomes 10. FR is non-heated~1
00°C, IDR is 60~150°C, 2DR is 100~
200°C Use 150 to 220°C for 13DR and 200°C to 200°C for RR.

A non-contact heating element such as a slit heater (22) or superheated steam (23) is provided between the IDR and 2DR and between 2DR and 3DR. When using a slit heater between the IDR and 2DR, the temperature is at least 0 in a high temperature atmosphere of 80 to 250℃.
．． 02 seconds or more, and when using superheated steam, the nozzle temperature is 150 to 300 from the high temperature pressurized steam nozzle.
The high temperature steam of C is injected. When installing between 2DR and 3DR, set the slit heater to 1000 or higher and the superheated steam to 200°C or higher, each at a higher temperature than between IDR and 2[)8. In the production of the fibers of the present invention, it is preferable to use the above-mentioned non-contact heating body and heating roll group in the gyroscope drawing method. It is more preferable that the number of times per winding is two or less. This is because the amount of heat applied by the heating rolls is preferably kept to the minimum necessary for stretching. The number of times the yarn is wound around the final draw roll and the roll for subsequent heat setting is selected depending on the degree of heat setting required, and is usually 5 to 12 times.

The yarn that has passed through the 3DR (20) is relaxed or slightly stretched by 0.90 to 1.05 between the yarn and the RR (21) and is wound up by a winder (24).

According to the above method, it is possible to stably stretch the film at a maximum stretching ratio of 0.90 or more, usually 0.95 or more.

By this method, high-strength, low-shrinkage polyamide fibers having the following characteristics can be stably and efficiently produced.

Strength T/D≧log/d Elongation
E=10-20% boiling water shrinkage rate △S≦1
0% The fibers produced according to the invention and having the above properties are also characterized by the following fiber structure parameters.

Birefringence △n≧58X10°3 Density ρ≧1.142g/ccDSC melting point Tm≧217°C Crystal orientation fc≧0.92 Amorphous molecular orientation F=0.70 to 0.85 [Example] Next The method for measuring fiber properties and fiber structure parameters according to the present invention will be explained based on examples as follows.

(a) Strength T/D, elongation E, and initial tensile resistance
M1 According to JIS-L1017. Take the sample in the form of a cold, and
After being left in a temperature-humidity controlled room at 0°C and 65% RH for more than 24 hours, it was tested using a "Tensilon UTL-4L" type tensile tester (manufactured by Toyo Baldwin Co., Ltd.) with a sample length of 25 cm.
Measurement was performed at a tensile speed of 30 cm/min.

(B) Boiling water shrinkage rate △S A sample was taken in the form of a cold, left in a temperature and humidity controlled room at 20°C and 65% RH for more than 24 hours, and then measured by applying a load equivalent to 0°13/d of the sample. Length.

The sample was placed in a cloth bag and treated in boiling water for 30 minutes without tension. The treated sample was air-dried, left in the temperature and humidity control room for 24 hours or more, and then the load was applied again, and the measured length Lo was calculated using the following formula.

Boiling water shrinkage rate (%') = (L-Lo) /LO (c)
Birefringence △n It was determined using a Nikon polarizing microscope POH type using a conventional Berek convenscator method.

(d) Density ρ Using a density gradient tube made of carbon tetrachloride-toluene, 25
Measured at °C.

(E) DSC melting point Tm DSC-IB model manufactured by Perkin-E1mer, heating rate 10 kminl, sample amount 4.0 mg, sensitivity 4 m
It was taken as the peak temperature of the melting curve measured at cal·s-1 full scale.

(f) Crystal orientation fc Using a wide-angle X-ray scattering device D3-F manufactured by Rigaku, Cu
Measurements were made using Kα as a radiation source. It was calculated by the following formula from the half-width HO of the intensity distribution curve along the Debye ring of (200) equatorial line interference, where fc is the orientation function of the crystal part.

fc = (1800-HO)/1800 (g) Number of amorphous molecule orientations F The sample was immersed in a 0.2% by weight aqueous solution of the fluorescent agent "Whitex RP" (manufactured by Sumitomo Chemical) at 20°C for 2 hours overnight. Then, the sample was thoroughly washed and air-dried to prepare a measurement sample.The relative intensity of the polarized fluorescence was measured using a FOM-19 photometer manufactured by JASCO ■, and F was determined by the following formula.

F= 1-B/A However, A: ! Relative intensity B of Ii fiber axis blade axial optical fluorescence
: Relative strength in the direction perpendicular to the fiber axis [Example] 0.015% by weight of anhydrous copper acetate (52 ppm as copper),
Potassium iodide 0.1% by weight, and potassium bromide 0.1%
Cabramid chips containing ηr=3.8 were spun using an extruder type spinning machine. The discharge amount was adjusted so that the fineness of the drawn yarn was about 473 denier (D) at spinning speeds of less than 3,000 m/min, and about 315 denier (D) at spinning speeds of 3,000 m/min or more. Further, the mouthpiece had a hole diameter of 0.3 mmφ, and in order to change the discharge amount per tooth of the mouthpiece hole, tests were conducted by changing the total discharge amount and the number of mouthpiece holes. The polymer temperature was 290°C. Metal powder with a roughness of about 100 mesh, and 7μ
After filtering through a pack consisting of sequentially arranged stainless steel WA'm fiber sintered filters having pores of
It was spun from a 70k gold spinning hole.

As shown in Fig. 1, a pressurized spinning tube is constituted by the spinneret, the spinning bag, the following heating tube, a heat insulating plate, an annular cold air blowing device, and a duct having a seal nozzle at the bottom, and each of them is sealed from the other. It is connected. The components of the pressurized spinning tube had the following specifications and conditions. A heating tube with a length of 30 cm was attached directly below the cap, and the surrounding air temperature under the cap was heated to 300°C. Ambient temperature is a position 15 cm below the upper end of the heating cylinder and 1 cm below the outermost thread.
This is the temperature measured at a position just below mJ.

A 30cm insulating plate is placed under the heating cylinder through a 1cm long heat insulating plate.
A long annular cold air blower was installed.

Furthermore, a duct with a length of 3 m was attached to the lower part of the annular cold air blowing device, and a seal nozzle serving as an outlet for the spun yarn was attached to the lower end. Note that the seal nozzle is made of ceramic and has a hole diameter of 2 mm. A water-based emulsion was applied from the upper part of the seal nozzle to the yarn cooled and solidified in the pressurized spinning cylinder so as to adhere to 0.1% by weight to prevent the yarn from being scratched on the seal nozzle surface. Compressed air at a temperature of about 30° C. was rectified from the annular cold air blowing device, and the inside of the spinning cylinder was kept at a predetermined pressure for spinning.

The spun yarn drawn out from the pressurized spinning tube was coated with an aqueous emulsion in an amount of about 1% by weight based on the yarn by oil supply rolls arranged in two stages facing the yarn. Next, the yarn was taken up by a take-up roll rotating at a predetermined speed and wound up as is, or it was continuously stretched between drawing rolls and then wound up. . Next, the undrawn yarn taken out is transferred to the second
After 3-stage stretching and heat treatment using the drawing machine shown in the figure, winding
It was made into a drawn yarn. Here, the yarn was wound around the IDR and 2DR twice. Next, four or six drawn yarns were combined to obtain a 1890D yarn.

The spinning and drawing conditions are shown in Table 1, and the properties of the obtained yarn are shown in Table 2.

Next, the raw yarn is first twisted to 32T/10cm, and then the two first twisted cords are twisted to 32T/10cm in the opposite direction to the first twist.
It was twisted into a raw cord. Next, adhesive was applied and heat treated using a dippin machine manufactured by Ritzler. R.F.L.
The sample was immersed in the liquid, and the night concentration and liquid draining conditions were adjusted so that the adhesion amount was 5%.

Next, pass through a drying zone at a constant speed of 130 for 90 seconds,
The heat treatment zone was heated to 200C for 140 seconds, and the stress at the exit of the heat treatment zone (the value obtained by dividing the tension by the treated cord fineness) was approximately 1 g/
It was stretched so that it passed. The normal zone was passed through at 200° C. for 40 seconds with 1% relaxation.

The treated cords were then subjected to rubber vulcanization treatment, and the strength after vulcanization was measured. The vulcanization treatment conditions are as follows.

The treated cord was placed parallel to the unvulcanized rubber topping sheet, set in a mold together with another unvulcanized rubber sheet, and vulcanized for 30 minutes using a heat press machine set at 160, 170, and 180°C. . Immediately after taking out the mold from the heat press machine, the mold was cooled with water to allow the cord in the rubber to rapidly contract freely. Next, take out the cord from the rubber sheet and store it at 20℃ and 65%R for more than 24 hours.
The strength after vulcanization was measured after being left in a temperature/humidity controlled room.

The properties of the treated coat and the post-vulcanization coat are shown in Table 3.

The coating properties were measured as follows.

(1) Dry heat shrinkage rate △SO The dry heat shrinkage rate was measured in the same manner as the boiling water shrinkage rate of the yarn described above, except that the processing conditions were changed to 1 degree in an oven at 177°C.

(2) Intermediate elongation ME Similar to the above-mentioned strength and elongation, 10. 11 The offshore degree was determined and taken as the intermediate elongation.

(3) Strong utilization rate raw cord: (Strong raw cord/Strong yarn strength x 2) x 10
0% Processing code: (Strong processing code/Strong raw code) XIQ
O% Vulcanization code: (Strong vulcanization code/Strong processing code) X1
00% (4) GY fatigue life, according to JIS L-10173, 2, 2, 1 (1) A method.

Under the manufacturing conditions shown in Table 1, none of Comparative Examples (1) to (5) satisfied the scope of the present invention.

As a result, in terms of the a-fiber and tire coat properties in Tables 2 and 3, Examples 1 to 5 according to the present invention had high strength, dimensional stability, high fatigue resistance, and high vulcanization. In contrast, Comparative Examples (1) and (2) and Comparative Example (6) are inferior in strength, dimensional stability, fatigue resistance, and vulcanizing fluid strength, while the after strength is excellent. Comparative Example (3) has good strength and dimensional stability, but is poor in fatigue resistance and vulcanizing fluid strength. Comparative example (4) has high strength but is inferior in other properties. Comparative Example (5) has good dimensional stability, fatigue resistance, and good strength utilization after vulcanization, but the treated cord strength is low, so the absolute value of the vulcanizing solution strength is not high.

As mentioned above, in order to satisfy useful tire cord characteristics, it is necessary that the polycapramide fiber is produced by the method specified in the present invention.

〔Effect of the invention〕

The effects of the present invention are as follows.

(1) The polycapramide fiber obtained by the method of the present invention has a high strength of 10 g/d or more, usually 11 g/d or more, and also has excellent dimensional stability and fatigue resistance, so it can be used in various industrial applications, such as tire cords, etc. ~゛l＼l＼ Com reinforcing coats such as healds, robes, seat belts, etc.
It becomes a product with excellent durability when used for sewing thread, fishing nets, various cover sheets, etc.

(2) Not only the raw yarn strength but also the strength utilization rate in the subsequent tire cord processing process is high, so both the raw cord and the treated cord strength are high, and the decrease in strength is particularly small in the vulcanization process during tire processing. The strength of the cord after vulcanization is at least 10% higher, usually 15% higher than that of a conventional tire cord made of polyamide F'*Sl. By taking advantage of this feature7)), a tire with unprecedented high durability can be obtained, and since the amount of material used can be reduced, a lightweight tire can be obtained.

3) According to the method of the present invention, polycapramide* fibers having the above-mentioned useful properties can be produced with high production efficiency and high yield by a high-speed spinning/drawing method, so that a significant reduction in production costs can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing one embodiment of the spinning process according to the present invention. FIG. 2 is a process diagram showing one embodiment of the stretching method according to the present invention.

Claims (1)

[Scope of Claims] A method for producing polycapramide fibers by melt-spinning and stretching polycapramide, which is composed of at least 95 mol% of ε-capramide units and has a high degree of polymerization with a relative viscosity of sulfuric acid of 3.0 or more. ) The molten polymer is spun from a spinneret, guided into a pressurized spinning tube that is provided directly below the spinneret and maintained at a pressure 1 kg/cm^2 or more higher than the outside air pressure, cooled and solidified, and then the pressurized fiber is spun. Pass the seal nozzle from the bottom end of the cylinder to the outside air normal pressure area and take it out.
2) In the above method, at least 10
A heated cylinder is installed so that the atmosphere over cm is at a temperature higher than the melting point of the polyamide + 30°C, and the spun yarn passes through the high temperature atmosphere and then through the enclosed area, and then (3) The amount of polymer per hole of the spinneret is 2.5 g/min.
(4) The birefringence of the drawn yarn is 20×10^-^3 or more. After spinning to satisfy the following conditions: A method for producing polycapramide fiber, which is carried out at a stretching ratio of 90% or more, and at a total stretching ratio of 1.2 times or more and 3.5 times or less.