JP2008133566A - Method for producing polyamide fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing at low cost a polyamide fiber with both small total fineness and single filament fineness suitable for air bags in particular, through slight fluffings/yarn breakages, etc. in the yarn manufacturing process with excellent process passableness in undergoing higher-order processings. <P>SOLUTION: The method for producing the polyamide fiber 3.0-4.0 in sulfuric acid relative viscosity and 200-400 dtex in total fineness comprises the following process: A polyamide is made into a spun filament yarn using a spinneret with 150-400 nozzle holes. The spun filament yarn is then cooled using a crossflow-type cooling unit. When the single filament in the closest proximity to the cooling air blowing face of the cooling unit comes to a velocity standing at 97% or higher of the spinning velocity, the spun filament yarn is cooled so that the single filament lying farthest off the cooling air blowing face come to a velocity standing at 80-95% of the spinning velocity. Subsequently, the cooled filament yarn is sized, taken up on a take-up roll, drawn, and then wound. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a polyamide fiber. More specifically, the present invention relates to a method for producing a high toughness polyamide fiber suitable for industrial materials having high strength and high elongation both having a small total fineness and a single yarn fineness. More specifically, the present invention relates to a method for producing high toughness polyamide fibers which can be manufactured at low cost with little fluff and yarn breakage during yarn production, and have excellent processability during high-order processing, and are particularly suitable for use in airbags. is there.

  Polyamide fibers are excellent in mechanical properties and chemical properties, and are widely used in clothing and industrial applications. In industrial applications, it is suitably used for airbags, tire cords, ropes, nets and the like, and is particularly useful in airbag applications.

  In recent years, the installation area of automobile occupant protection airbags has increased, and in addition to conventional driver and passenger airbags, side airbags, knee airbags, inflatable curtain airbags, etc. have been put into practical use. Yes. In order to obtain a base fabric suitable for these various uses, fibers with small total fineness and single yarn fineness are increasingly demanded in recent years, and these fibers are used in various looms such as water jet loom and air jet loom. We are trying to manufacture at low cost.

  However, if we attempt to weave these polyamide fibers with small total fineness or single yarn fineness at high speed, weaving of the loom frequently occurs due to fluffing or the quality of the obtained base fabric is lowered. It has been necessary to reduce the speed or perform sizing and the like, and it has been difficult to produce an airbag base fabric at low cost.

  For example, Patent Document 1 discloses a polyhexamethylene adipamide having a small single yarn cross-sectional area, excellent toughness, high entanglement, uniform and relatively high entanglement strength. A technique for obtaining a fabric for high-density industrial materials that is excellent in high-speed weaving at the time of high-density weaving and excellent in quality after weaving without using sizing is disclosed. Certainly, the fabric described in Patent Document 1 may have a slight effect of improving weaving. However, since the fabric has high entanglement, particularly with a polyamide fiber having a large number of single yarns and a small single yarn fineness, single yarn slack occurs when the high entangled yarn is obtained, and satisfactory weaving properties cannot be obtained. There wasn't. Especially in weaving in the air jet loom, single yarn slack catches on the sub nozzle, causing fluff and weaving stops, and because of high entanglement, a large amount of air flow is required to fly the weft. There was a problem. On the other hand, in weaving in the water jet loom, most of the entanglement is unraveled during weaving, so that the effect of the high entanglement applied is reduced, and the fluff that was difficult to find by the entanglement process becomes apparent as a long single yarn breakage. In addition, there is a problem in that the single yarn whose strength and elongation characteristics are reduced due to damage during high entanglement treatment is fluffed during weaving, which reduces the weaving efficiency.

  In Patent Document 2, as a method for producing a polyamide fiber suitable for industrial materials such as an air bag at a low cost, even if simultaneous stretching and winding of 8 or more yarns at a speed of 3000 m / min or more are performed, yarn There has been disclosed a direct spinning drawing method that can produce a synthetic fiber with few yields and single yarn breaks and excellent yield and quality. However, this method mainly discloses only the stretched portion, and it has been difficult to obtain a polyamide fiber having a small total fineness and single yarn fineness as well. That is, when the total fineness and single yarn fineness are reduced by the method described in Patent Document 2, the fluff quality and yarn-making property of the obtained polyamide fiber are deteriorated. On the other hand, if we try to obtain the same fluff quality and yarn-making performance as conventional polyamide fibers with a small number of single yarns, the production speed will be low, and the required thin polyamide fibers will be manufactured at low cost. I couldn't. In particular, when trying to obtain a spun yarn of two or more yarns with a single die as described in the examples, there is a problem in that fusion of undrawn yarns and winding of a single yarn around a take-up roller frequently occur. There was a desire to improve spinning technology.

In Patent Document 3, high-strength polyamide fibers suitable for industrial materials can be obtained at higher speed by moving the quenching gas in the same direction as the filament direction in the filament cooling and solidification process during melt spinning. Technology is disclosed. However, in this method, not only a large number of spun yarns can be obtained from a single die, but also a special cooling device is required.
JP-A-2005-344266 (Claims) JP-A-10-251913 (Claims) JP 2005-527714 A (Patents)

  The present invention has been achieved as a result of studying the above-described problems in the prior art as a subject, and can be manufactured at low cost with less fuzz and yarn breakage during yarn production. An object of the present invention is to provide a method for producing a high toughness polyamide fiber which has excellent permeability and is particularly suitable for use in an airbag and has a small total fineness and single yarn fineness.

  As a result of intensive studies on the above-mentioned problems by the present inventors, a method for producing a polyamide fiber having a relative viscosity of sulfuric acid of 3.0 to 4.0 and a total fineness of 200 to 400 dtex, the polyamide having 150 to 400 holes. The spinneret is used to form a spun yarn, the spun yarn is cooled using a cross-flow type cooling device, and the single yarn closest to the cooling air blowing surface from the cooling device is 97% or more of the spinning speed. After cooling so that the single yarn farthest from the cooling air blowing surface is 80 to 95% of the spinning speed, an oil agent is applied to the cooling yarn and taken up by a take-up roll and taken up. It has been found that the above-mentioned problems can be solved by using a method for producing a polyamide fiber characterized by winding a subsequent yarn after drawing.

In the method for producing a polyamide fiber of the present invention,
The spinning speed is 500 to 1000 m / min, and the speed CV value of the single yarn farthest from the cooling air blowing surface is 1 to 40%;
Contacting the cooling thread with metal or ceramics immediately before applying the oil to the cooling thread,
It is preferable to install a member that surrounds the cross-flow type cooling device, and to divide the spun yarn obtained by spinning from the spinneret into 2 to 4 yarns and draw them, and then wind them up. Therefore, by applying these conditions, a further excellent effect can be expected.

  According to the present invention, as will be described below, high-toughness and high-efficiency production of high-toughness polyamide fibers suitable for industrial material applications with low total fineness and single yarn fineness and high elongation, particularly for airbag applications. And can be manufactured inexpensively. Moreover, if the high toughness polyamide fiber obtained by the method of the present invention is used, it can be woven at high speed and with high quality by various looms such as a water jet loom and an air jet loom.

   Hereinafter, the present invention will be described in detail.

  In the manufacturing method of the polyamide fiber of this invention, it is required to manufacture so that a sulfuric acid relative viscosity may be 3.0-4.0, and the total fineness may be 200-400 dtex. When the relative viscosity of sulfuric acid is less than 3.0, high-strength fibers suitable for industrial use cannot be obtained stably. On the other hand, it is possible to obtain a high-viscosity polyamide fiber exceeding 4.0, but it is not preferable because it requires time for solid-phase polymerization of the raw material and the production cost increases. Further, if the total fineness is less than 200 dtex, it is difficult to obtain high-strength fibers for industrial use, and gelation due to long-term melting of the polymer tends to occur, such being undesirable. Furthermore, since the single yarn fineness becomes too small, it may be difficult to perform stable spinning, which is not preferable. On the contrary, if it exceeds 400 dtex, it is not preferable because the storage compactness of the airbag is impaired and it is difficult to stably obtain a yarn having a small single yarn fineness.

In the method for producing a polyamide fiber of the present invention, it is necessary to obtain a spun yarn by using a spinneret having 150 to 400 holes, preferably 170 to 350, more preferably 220 to A spinneret with 320 holes is used. If the number of holes is less than 150, for example, when trying to obtain two yarn fibers, the number of single yarns will be less than 75, making it difficult to obtain polyamide fibers with a small single yarn fineness. On the other hand, when the number exceeds 400, the hole interval, that is, the interval between the extruded single yarns in the melted state becomes excessively narrow, which is not preferable because the undrawn yarn is fused. In particular, when trying to obtain two or more fibers, it is necessary to ensure a certain or more thread interval between the discharge hole groups forming one thread, and the discharge hole interval for forming one thread is It becomes narrower. The single yarn fineness is preferably 1 to 4 dtex, and more preferably 1.5 to 3 dtex. A yarn having a single yarn fineness of less than 1 dtex is not preferred because it cannot be stably obtained by the current direct spinning drawing technique, and single yarn breakage may occur frequently during weaving. Moreover, if it exceeds 4 dtex, the storage compactness of the airbag is impaired, which is not preferable. The hole spec of the base is preferably designed to be at least 60 kg / cm ² or more so as to increase the back pressure, and is preferably 80 to 120 kg / cm ² when the single yarn fineness is small. It can be adjusted as appropriate according to the degree of variation.

  In the method for producing a polyamide fiber of the present invention, it is necessary to use a cross flow type cooling device. It is not preferable to use a cooling device other than the cross flow type because a special device is required.

  Further, in order to cool a yarn having a single yarn fineness of 3 to 4 dtex or more, a large apparatus having a long cooling length is required. For example, when manufacturing using a cylindrical cooling apparatus, this cooling apparatus Occupies a large work space, which significantly impairs the work of correcting the base surface performed in the production of ordinary synthetic fibers. However, such a situation can be avoided if a cross-flow type cooling device is used. Further, when the cooling gas is blown out from one direction as in a cross-flow type cooling device, it becomes easy to obtain a multi-thread spun yarn. For example, when a spun yarn of two yarns is obtained, the yarns may be separated by a plane that is orthogonal to the cooling gas blowing surface and that divides the surface into two in the longitudinal direction.

  In the polyamide fiber manufacturing method of the present invention, when the single yarn closest to the cooling air blowing surface from the cooling device reaches 97% or more of the spinning speed, the single yarn furthest from the cooling air blowing surface is the spinning speed. It is necessary to make it cool so that it may become 80 to 95% of speed | rate, and 85 to 90% is more preferable. In the production of conventional polyamide fibers having a large single yarn fineness, that is, a small number of single yarns, consideration is usually given to uniformly heating and uniformly cooling each spun single yarn extruded from the spinneret. However, when producing polyamide fibers with small total fineness and single yarn fineness and a large number of single yarns using a cross-flow type cooling device, it has been found that it is better to cool each single yarn unevenly. . When cooling uniformly so that the speed of each single yarn is substantially equal, that is, when cooling so that the single yarn furthest from the cooling air blowing surface exceeds 95% of the spinning speed, the cooling gas blowing speed is set to It was considered effective to increase the size or heat the single yarn group closer to the cooling gas blowing surface to a higher temperature before cooling. However, in the former method, the cooling gas must be blown out at a speed larger than the cooling gas blowing speed at the time of producing the conventional polyamide fiber having a large single yarn fineness, that is, a small number of single yarns. In the latter method, the difference in physical properties between the single yarns of the finally obtained polyamide fiber increases. On the other hand, when the speed difference between the single yarns becomes too large, that is, when the single yarn farthest from the cooling air blowing surface has a speed of less than 80% of the spinning speed, the yarn sway at the spinning portion becomes large and the undrawn yarn Fusing occurs, and yarn breakage and fluff frequently occur during stretching.

  When the single yarn closest to the cooling air blowing surface from the cooling device reaches 97% or more of the spinning speed, the single yarn farthest from the cooling air blowing surface is 80 to 95% of the spinning speed. If non-uniform cooling such as cooling is simply performed, the physical properties between the single yarns of the drawn yarn may vary. If this variation is unacceptably large, it is preferable to make the properties of undrawn yarn uniform by appropriately combining methods such as heating a single yarn group far from the cooling gas blowing surface to a higher temperature before cooling. For example, it is possible to adopt a non-uniform heating method of the pre-cooling yarn with a temperature gradient, such as increasing the temperature of the heating cylinder opposite to the heating cylinder temperature on the cooling device side, but the same effect is obtained. If possible, these methods are not limited at all.

  Further, the speed CV value of the single yarn farthest from the cooling air blowing surface is preferably 1 to 40%, and more preferably 5 to 30%. Manufacturing with less than 1% is impossible with current technology. Conversely, if it exceeds 40%, the yarn swing of the spun yarn is extremely large, and it is difficult to achieve the object of the present invention.

  The heating cylinder may be 5 to 40 cm long and heated so that the atmospheric temperature in the cylinder becomes 200 to 350 ° C. If necessary, an unheated heat insulating cylinder is attached below the heating cylinder, It is possible to control the length of the wire, but it is possible to install a plurality of heaters that can individually set each temperature in one heating cylinder so that the yarn before cooling can be heated unevenly. preferable. The cooling can be performed by blowing a cooling air of 10 to 100 ° C. at a speed of 20 to 40 m / min, preferably 25 to 35 m / min.

  It is necessary to apply an oil agent to the obtained cooling yarn, take it up with a take-up roll, stretch the yarn, and then wind it. As the oil agent, a known oil agent can be used. However, in order to suppress winding of the single yarn on the take-up roll, the amount of adhesion is 0.3 to 1.5 with respect to 100% by weight of the total amount of the yarn and the oil agent. % By weight is preferred, and more preferably 0.5 to 1.0% by weight.

  The spinning speed defined by the rotation speed of the take-up roll is preferably 500 to 1000 m / min, more preferably 700 to 900 m / min. If the spinning speed is less than 500 m / min, the final production speed will be low, and it will be difficult to produce polyamide fibers at low cost. Spinning at a high speed exceeding 1000 m / min is not preferable because the speed difference between individual yarns tends to be outside the scope of the present invention, and yarn breakage and fluff frequently occur.

  Moreover, it is preferable to bring the cooling yarn into contact with a metal or ceramic immediately before applying the oil to the cooling yarn. In the production of synthetic fibers, bringing these metals and ceramics into contact with the yarn before application of the oil agent is not usually performed because it tends to cause adverse effects such as deterioration of physical properties and generation of fluff due to abrasion. However, it has been found that this method works effectively in order to stably obtain fibers with a small total fineness or single yarn fineness so that each single yarn can be evenly lubricated. For example, when roller lubrication is performed, the single yarn spreads without converging on the roller by this method, and uniform lubrication between single yarns is realized. These metals and ceramics may be a rotating small-diameter roller or a plate, but in order to obtain a contact strength such that each single yarn spreads uniformly, the installation position should be adjusted appropriately. Is preferred. Moreover, these surface states should just be a well-known satin state, and the raw material can be suitably selected, such as SUS.

  Furthermore, in the method for producing a polyamide fiber of the present invention, if a member surrounding a cross-flow type cooling device is installed, more stable yarn production can be realized. This member produces the effect of suppressing the yarn swing of the spun yarn.

  In addition, if the spun yarn obtained by spinning from the spinneret is divided into 2 to 4 yarns and stretched, and then wound, a polyamide fiber can be obtained at a lower cost. It is almost impossible to make more than 5 yarns with the current technology.

  These spun yarns obtained by the above-described methods can be stretched, relaxed and heat-treated and wound using known methods, and have a strength of 7.0 to 9.0 cN / dtex and an elongation of 20 A polyamide fiber having -30% boiling water shrinkage of 4-15% can be obtained.

  In addition, the entanglement to be applied to the yarn can be appropriately selected according to the type of loom and the weaving speed, but if the method according to the present invention is used, there is no need to excessively entangle the number of entanglements of 15 to 25 pieces / m. What is necessary is just to change the kind and provision conditions of a confounding provision apparatus so that can be obtained. Even if it greatly falls below 15 pieces / m or exceeds 25 pieces / m, the high-order process passability tends to deteriorate. Similarly, the entanglement strength may be within a known range.

  The polyamide fiber produced in the present invention may be made of any polyamide polymer such as polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46) and the like. Is preferably polyhexamethylene adipamide. These polyamides may be copolymers containing 5% by weight or less of a copolymer component. Examples of the copolymer component used in the present invention include ε-caproamide, tetramethylene adipamide, hexamethylene sebacamide, hexamethylene isophthalamide, tetramethylene terephthalamide, and xylylene phthalamide. Additives such as weathering agents, heat-resistant agents, antioxidants and the like can be added to the above-mentioned polyamide chips that have been made highly viscous by solid-phase polymerization, and melt-spun. A part or all of the additives may be added during the polymerization, or may be mixed by other methods. Moreover, in order to adjust the amino terminal group amount, the polyamide chip may or may not contain diamine, monocarboxylic acid, or the like, and may be adjusted so that the target amino terminal group amount is appropriately obtained.

  Moreover, the single yarn cross-sectional shape of the polyamide fiber of the present invention is not particularly limited, and it can be circular or non-circular such as Y-type, V-type, flat type, etc., but is preferably circular.

  Thus, when a polyamide fiber having a small total fineness and a single yarn fineness is produced by the method of the present invention, a polyamide fiber excellent in yarn-making property and fluff quality can be obtained at a low cost. In other words, by using the direct spinning drawing method, it is possible to efficiently produce fine and high-toughness polyamide fibers using a multi-yarn simultaneous drawing method with a yarn production speed of 3000 m / min or more and 8 yarns or more. A level comparable to that of the production of polyamide fibers can be obtained.

  In addition, the polyamide fiber having high toughness obtained by the method of the present invention has good high-order process passability such as weaving property even when using various looms capable of high-speed weaving such as water jet loom and air jet loom, In addition, an inexpensive base fabric excellent in quality after weaving can be obtained.

  The high toughness polyamide fiber obtained by the method of the present invention has a small total fineness and single yarn fineness in addition to the above-mentioned advantages, and can be usefully used particularly for industrial materials such as airbags. Further, the airbag base fabric can be applied to both non-coated products and coated products, and can be used as a versatile airbag fabric that can be attached to various parts.

  Hereinafter, the present invention will be described in detail by way of examples. The definition of each characteristic and the measuring method in the present invention are as follows.

  (1) Sulfuric acid relative viscosity: 2.5 g of a sample was dissolved in 25 cc of 96% concentrated sulfuric acid and measured using an Ostwald viscometer at a constant temperature in a thermostatic bath at 25 ° C.

  (2) Total fineness: JIS L1013 (1999) 8.3.1 According to the A method, the positive fineness was measured at a predetermined load of 0.045 cN / dtex and a predetermined yarn length of 180 m to obtain the total fineness.

  (3) Number of single yarns: Calculated by the method of JIS L1013 (1999) 8.4.

  (4) Single yarn fineness: The single fiber fineness (dtex) was calculated by dividing the total fineness by the number of single yarns.

  (5) Strength / Elongation: Measured under constant speed elongation conditions shown in JIS L1013 8.5.1 standard time test. The sample used was “TENSILON” UCT-100 manufactured by Orientec Co., Ltd., with a grip interval of 25 cm and a pulling speed of 30 cm / min. The number of tests was 10 and the average value was obtained. In addition, elongation was calculated | required from elongation of the point which showed the maximum strength in a SS curve.

(6) Boiling water shrinkage ratio: Sampling the raw yarn in a crushed shape, adjusting it in a temperature / humidity adjustment chamber at 20 ° C. and 65% RH for 24 hours or longer, and applying a load equivalent to 0.045 cN / dtex to the sample The thickness L ₀ was measured. Next, after immersing the sample in boiling water for 30 minutes in an unstrained state, the sample was air-dried for 4 hours in the temperature / humidity adjusting chamber, and a length L ₁ was measured by applying a load equivalent to 0.045 cN / dtex to the sample again. did. The boiling water shrinkage was calculated from the respective lengths L ₀ and L _{1 according} to the following equation.
Boiling water shrinkage = [(L ₀ −L ₁ ) / L ₀ ] × 100 (%)

  (7) Oil adhesion amount: The diethyl ether extract was measured by the method of JIS L1013 (1999) 8.27 b) to obtain the oil adhesion amount.

  (8) Number of entanglements: The number of entangled portions having a length of 1 mm or more was measured by a water immersion method and converted to the number per 1 m. Ten raw yarns were measured and indicated by the average value.

  As the water immersion bath, a bath having a length of 70 cm, a width of 15 cm, and a depth of 5 cm and provided with a partition plate at a position 10 cm from both ends in the longitudinal direction was used. The bath was filled with pure water, the raw yarn sample was immersed in water, and the number of entangled portions was measured. In addition, in order to exclude the influence of impurities, such as an oil agent, the pure water was replaced | exchanged for every measurement.

(9) Speed of spinning yarn Using a semiconductor laser (LS50M) manufactured by TSI, the speed of the single yarn was measured in the HISTOGRAPH mode. The wavelength of the laser light is near infrared of 780 nm, and the beam diameter is φ1 mm.

  The speed measurement of the single yarn closest to the cooling air blowing surface from the cooling device was performed while sucking a large number of single yarns on the side opposite to the cooling device at the spinning part in consideration of the focal length of the laser beam. The main unit was fixed with a tripod, and measurement was performed at an interval of 5 cm from the top of the cooling device, and the measurement was continued until a point at which the speed of the take-up roller reached 97% or more (hereinafter referred to as a solidification completion point). In addition, it measured until N number became 300 points in each measurement, and the average value (M) calculated automatically was considered as the actual single yarn speed.

  The speed measurement of the single yarn farthest from the cooling air blowing surface from the cooling device was carried out while producing all single yarns. Measurement was performed at the same height as the solidification completion point obtained to obtain the actual single yarn speed. Further, the speed CV value was calculated from the equation of M / σ × 100 using the standard deviation σ calculated automatically as in the case of the average value (M).

  (10) Yarn breakage: The number of yarn breakage per 10,000 km of fiber length. The number of yarn breaks is the product of the number of yarn breaks and the number of yarns drawn at the same time.

  (11) Yarn fluff: A laser type fluff detector was installed at a location 5 mm away from the roller between the stretching and relaxation heat treatment and the entanglement imparting device, and the number of detected fluff was converted into the number per 10,000 km and displayed.

  (12) Package internal defects: The obtained fiber package is rewound at a speed of 500 m / min, a laser type fluff detector is installed at a position 2 mm away from the yarn being rewound, and the total number of detected defects is 100,000 m. Displayed in terms of number per unit.

  (13) Weaving property: Evaluated by the value of the loom operating rate.

[Examples 1-4 and Comparative Examples 1-2]
Nylon 66 pellets having a 98% sulfuric acid relative viscosity of 3.8 measured at 25 ° C. and containing 68 ppm of copper acetate as copper were fed to an extruder, placed in a spinneret with a metering pump, and melt-spun at 295 ° C. The discharge amount and the spinneret were set and used as shown in Tables 1 and 3 so as to obtain a yarn having a total fineness of 350 dtex and a predetermined number of single yarns. A 200 mm heating cylinder heated to 220 to 320 ° C. is provided immediately below the base, and after the yarn is slowly cooled, it is cooled and solidified with cold air at 20 ° C. and 30 to 40 m / min using a cross-flow type cooling device, Next, an aqueous emulsion having a smoothing agent or the like was applied, wound around a spinning take-up roller, and the spun yarn was taken up. Moreover, the metal plate just before oil agent provision and the cooling device surrounding member were installed as needed. Subsequently, the yarn was continuously supplied to the drawing / heat treatment zone, and nylon 66 fibers were produced by a direct spinning drawing method.

  First, a stretch of 3% is applied between the take-up roller and the yarn feeding roller, then the first drawing is performed between the yarn feeding roller and the first drawing roller, and the second drawing is performed between the first drawing roller and the second drawing roller. The eye was stretched. Subsequently, a 6% relaxation heat treatment was performed between the second stretching roller and the relaxation roller, the yarn was entangled with the entanglement imparting device, and then wound with a winder. The surface temperature of each roller was set so that the take-up roller was normal temperature, the yarn feeding roller was 40 ° C., the first stretching roller was 140 ° C., the second stretching roller was 220 ° C., and the relaxation roller was 150 ° C. The yarn was produced so that the peripheral speed of the take-up roller was 740 m / min and the overall draw ratio was 4.45 times. Moreover, the application amount of the water-based emulsion was adjusted so that the amount of oil adhering to the yarn became about 1.0% by weight. The entanglement process was performed by injecting high-pressure air from the direction perpendicular to the running yarn in the entanglement imparting device. A guide for regulating the running yarn was provided before and after the entanglement imparting device, and the pressure of the air to be injected was constant at 0.35 MPa.

  Tables 1 to 4 show the fiber production conditions including the measured value of the single yarn speed and the characteristics of the obtained nylon 66 fibers.

  About 2000 kg of nylon 66 fiber was produced using the above method. About 30 kg of the polyamide fiber was rewound at a speed of 500 m / min, and a package internal defect was examined using a laser type fluff detector.

  Tables 2 and 4 show the obtained yarn cutting, yarn fluff, and package fluff.

  Next, the nylon 66 fiber obtained above is warped at a speed of 300 m / min, and then woven at a rotational speed of 1000 rpm using a water jet loom (ZW303 type: hereinafter referred to as WJL) manufactured by Tsudakoma. A base fabric was obtained.

  The obtained weaving results are shown in Tables 2 and 4.

In Examples 1 to 4, although the single yarn fineness was thin, there were few yarn breakage and fluff at the time of yarn production, and weaving property was also good. In particular, in Example 4, the same result as that of Comparative Example 1 having a large single yarn fineness could be obtained.
On the other hand, in Comparative Example 2, yarn breakage and fluff frequently occurred and the weaving property was poor.

[Example 5]
The heating cylinder is configured so that the temperature can be divided into two on the side close to the cooling device and the side far from the cooling device, the temperature on the side close to the cooling device is 220 ° C., the temperature on the far side is 320 ° C. Nylon 66 fiber was obtained in the same manner as in Example 4 except that the pressure was 0.40 MPa. Next, the obtained nylon 66 fiber is warped at a speed of 300 m / min, and then a release speed of 543 m / min × 3 picks using an air jet loom (JAT610 type: hereinafter referred to as AJL) manufactured by Toyota Industries Corporation And woven fabric was obtained.

  Tables 1 and 2 show the production conditions of the nylon 66 fiber, the obtained fiber characteristics, and the results of yarn production and weaving.

  By using the nylon 66 fiber according to the production method of the present invention, good weaving properties could be obtained.

[Comparative Example 3]
Nylon 66 fiber was obtained in the same manner as in Example 4 except that a base having 432 discharge holes was used. Subsequently, a textile base fabric was produced in the same manner as in Example 5 except that 1.0 wt% additional oil was added.

  Tables 3 and 4 show the production conditions of the nylon 66 fiber, the obtained fiber characteristics, and the results of yarn production and weaving.

  When the fibers were produced in this manner, the number of single yarns was too large, and as a result of frequent yarn swinging and fusion of undrawn yarns at the spinning section, yarn breakage and fluff during yarn production increased. Moreover, despite the high entanglement, the weaving property was inferior.

[Comparative Example 4]
The heating cylinder is configured to be capable of two-part temperature control on the side closer to the cooling device and the side farther from the cooling device. Except for this, nylon 66 fibers were obtained in the same manner as in Example 5. Next, a fabric base fabric was produced in the same manner as in Example 1.

  Tables 3 and 4 show the production conditions of the nylon 66 fiber, the obtained fiber characteristics, and the results of yarn production and weaving.

  When the fibers are produced in this way, each single yarn can be cooled uniformly, but the yarn swings at the spinning section and the undrawn yarn is frequently fused, and fluffing occurs even during drawing, thereby producing the yarn. The yarn breakage and fluff increased. Moreover, the weaving property was also inferior.

[Comparative Example 5]
Similar to Example 4 except that nylon 66 pellets having a relative viscosity of 98% sulfuric acid measured at 25 ° C. of 2.7 are used and the total fineness is 180 dtex and the number of single yarns is 72. An attempt was made to obtain nylon 66 fiber, but even a sample could not be collected.

[Comparative Example 6]
Nylon 66 fibers were obtained in the same manner as in Example 4 except that the peripheral speed of the take-up roller was 1050 m / min, the overall draw ratio was 3.80 times, and the total fineness was 350 dtex. Nylon breakage and fluff frequently occurred, and it was not possible to obtain an amount of nylon 66 fiber enough to be woven.

  According to the present invention, a polyamide fiber having a small total fineness or single yarn fineness can be obtained by an inexpensive method with few defects such as yarn breakage and fluff during yarn production. Further, according to the present invention, it is possible to obtain a woven fabric for industrial materials represented by a base fabric for airbags at a low cost, which has excellent weaving properties that could not be achieved by conventional techniques.

  Therefore, the technique of the present invention greatly contributes to the improvement of safety awareness in the vehicle field, particularly in that field.

It is an example of the schematic diagram of the manufacturing method of this invention.

Explanation of symbols

1: Spinneret
2: Heating cylinder 3: Cross flow cooling device 4: Cooling air 5: Yarn 6: Duct 7: Oiling roller 8: Take-up roller 9: Yarn feeding roller 10: First stretching roller 11: Second stretching roller 12: Relaxing roller 13: Entangling device 14: Winder 15: Fiber package 16: Cooling device surrounding member 17: Metal plate

Claims (5)

  A method for producing a polyamide fiber having a relative viscosity of sulfuric acid of 3.0 to 4.0 and a total fineness of 200 to 400 dtex, wherein the polyamide is formed into a spun yarn using a spinneret having 150 to 400 holes, When the yarn is cooled using a cross-flow type cooling device and the single yarn closest to the cooling air blowing surface from the cooling device reaches 97% or more of the spinning speed, it is farthest from the cooling air blowing surface. After cooling so that the single yarn is 80 to 95% of the spinning speed, an oil agent is applied to the cooling yarn, it is taken up by a take-up roll, the drawn yarn is drawn and then wound. A method for producing a polyamide fiber.   The method for producing a polyamide fiber according to claim 1, wherein the spinning speed is 500 to 1000 m / min, and the speed CV value of the single yarn furthest from the cooling air blowing surface is 1 to 40%.   The method for producing a polyamide fiber according to claim 1 or 2, wherein the cooling yarn is brought into contact with a metal or ceramic immediately before the oil agent is applied to the cooling yarn.   The method for producing a polyamide fiber according to any one of claims 1 to 3, wherein a member surrounding the cross-flow type cooling device is installed.   The method for producing a polyamide fiber according to any one of claims 1 to 4, wherein a spun yarn obtained by spinning from a spinneret is divided into 2 to 4 yarns, drawn and then wound.

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