Polyamide multifilaments and methods for producing the same, and woven / knitted fabrics

Abstract

Provided is a polyamide multifilament characterized in that the strength thereof is 7.0 cN / dtex or more, elasticity is 33-50%, total fineness is 56 dtex or less, and fluffing / sagging is one or less per 100,000m.　The provided polyamide multifilament has high strength and appropriate elasticity, and fluffing / sagging is controlled. Furthermore, due to this polyamide multifilament, a woven / knitted article is provided having softness and a lightweight feel, and having excellent high-order transmissivity, product quality, and durability.

Description

Technical Field

[0001] The present invention relates to polyamide multifilaments. More specifically, the present invention relates to high-strength polyamide multifilaments capable of providing a thin woven or knitted fabric excellent in softness, lightness, and durability when the polyamide multifilaments of the present invention are used in a woven or knitted fabric.

Background Art

[0002] Polyamide fibers, which are synthetic fibers, have excellent properties such as their unique softness, high strength, color development during dyeing, heat resistance, and moisture absorption, and are thus widely used in clothing applications such as underwear and outdoor jackets.

[0003] With the recent global warming, the demand for functional underwear has increased, and there is a desire to improve the texture and reduce the thickness of knitted fabrics for underwear. In addition, with the spread of outdoor sports, there is a desire to reduce the weight and thickness of fabrics for sportswear. Along with the reduction in thickness, polyamide multifilaments have progressed in terms of fineness and single-filament fineness, but on the other hand, they are accompanied by a decrease in durability, and there has been a desire to pursue conventional durability, improved texture, and a sense of lightness.

[0004] For example, in Patent Document 1, by increasing the number of drawing rollers and performing drawing in multiple stages, high magnification drawing without fuzz is made possible, and a high-strength polyamide multifilament is obtained. With this high-strength polyamide multifilament, while maintaining high-order permeability, product quality, and durability, the pattern looks beautiful due to the transparency of the lace ground yarn, and a lace knitted fabric excellent in texture is provided.

[0005] In addition, in Patent Document 2, a heating cylinder is installed in the spinning section to give priority to relaxation of the orientation of the polymer, and a drawing process of performing low spinning speed and high magnification drawing in a single stage is used to efficiently construct a crystal structure, obtaining a high-strength polyamide multifilament having an appropriate fiber modulus. With this high-strength polyamide multifilament, while maintaining high-order permeability, product quality, and durability, the pattern looks beautiful due to the transparency of the lace ground yarn, and a lace knitted fabric and stockings excellent in texture are provided. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2019 / 146600 [Patent Document 2] International Publication No. 2018 / 021011 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the method described in Patent Document 1 achieves high strength by applying high-magnification stretching, resulting in an elongation of 23-33%, which is low for clothing applications. Furthermore, the fiber modulus is high, and the ability to pass through the manufacturing process of woven or knitted fabrics is significantly reduced depending on the processing conditions.

[0008] Furthermore, in the method described in Patent Document 2, as will be explained in detail later, in order to efficiently stretch the fabric, entanglement is introduced with a low entanglement strength before stretching. As a result, entanglement is undone by high-magnification stretching in a single stage, making it prone to fuzzing and sagging. This leads to problems such as poor passage through the woven or knitted fabric during the manufacturing process, and the occurrence of streaks, resulting in inferior product quality.

[0009] The present invention aims to solve the above problems, and given the trend towards thinner woven and knitted fabrics, which is leading to finer fiber density and finer single-fiber density, the objective is to provide a polyamide multifilament that has high strength, appropriate elongation, and suppresses fluffing and sagging. More specifically, the objective is to provide a woven or knitted fabric using the polyamide multifilament of the present invention that has softness and lightness, and is excellent in terms of high-level passage, product quality, and durability. [Means for solving the problem]

[0010] To solve the above problems, the present invention adopts the following configuration. (1) A polyamide multifilament characterized by having a strength of 7.0 cN / dtex or more, elongation of 33-50%, total fineness of 56 dtex or less, and one or fewer fluffs / slacks per 100,000 m. (2) The polyamide multifilament described in (1) above, characterized in that the dry heat shrinkage rate at 180°C is 12.0% or less. (3) A woven or knitted fabric that uses in part the polyamide multifilament described in (1) or (2). (4) A method for producing polyamide multifilaments by a direct spinning and drawing method, wherein a polyamide resin is melted, each filament extruded from a spinneret is cooled and solidified, lubrication and entanglement treatment are performed, and then the filaments are drawn and heat-treated by rollers of different peripheral speeds and wound up, the method for producing polyamide multifilaments according to claim 1, characterized in that it satisfies the following conditions (A) to (D). (A) Pre-stretch entanglement degree is 20-50, (B) Stretch ratio is 3.0-3.5, (C) Heat setting temperature is 35°C lower than or equal to 15°C lower than or equal to the melting point of the polyamide resin, (D) Winding tension between the stretch roller and winding device is 0.15-0.20 cN / dtex. [Effects of the Invention]

[0011] The present invention provides a polyamide multifilament with high strength, appropriate elongation, and suppressed fluffing and sagging. Furthermore, the present invention makes it possible to provide woven or knitted fabrics that are soft, lightweight, have high passability, and are excellent in product quality and durability. [Brief explanation of the drawing]

[0012] [Figure 1] A schematic diagram showing one embodiment of a manufacturing apparatus that can be preferably used in the method for manufacturing polyamide multifilaments of the present invention. [Modes for carrying out the invention]

[0013] The present invention will be described in more detail below.

[0014] The polyamide constituting the polyamide multifilament of the present invention is a resin made of a high molecular weight material in which so-called hydrocarbon groups are linked to the main chain via amide bonds. Such polyamides have excellent spinnability and mechanical properties, and polycaproamide (nylon 6) and polyhexamethylene adipamide (nylon 66) are preferred, with nylon 6 being even more preferred because it is less prone to gelation and has good spinnability. In the above, "primarily" means that in the case of polycaproamide, the ε-caprolactam units constituting polycaproamide are 80 mol% or more, and in the case of polyhexamethylene adipamide, the hexamethylenediammonium adipate units constituting polyhexamethylene adipamide are 80 mol% or more, and more preferably 90 mol% or more. Other components, though not particularly limited, include, for example, units such as aminocarboxylic acids, dicarboxylic acids, and diamines, which are monomers that make up polydodecanoamide, polyhexamethylene adipamide, polyhexamethylene azeramide, polyhexamethylene sevacamide, polyhexamethylene dodecanoamide, polymetaxylylene adipamide, polyhexamethylene terephthalamide, and polyhexamethylene isophthalamide.

[0015] Furthermore, in order to effectively exhibit the effects of the present invention, it is preferable that the polyamide does not contain various additives such as matting agents represented by titanium dioxide, but additives such as heat-resistant agents may be included as needed, within a range that does not hinder the effects. In addition, the content of these additives may be mixed as needed, between 0.001% and 0.3% by weight relative to the polymer.

[0016] The polyamide multifilament of the present invention has all of the total fineness, strength, elongation, and the number of hairiness and tarry per 100,000 m within the following ranges. That is, by reducing the total fineness, softness and a sense of lightness can be obtained, but durability deteriorates. On the other hand, since durability is proportional to the total fineness and the single-filament fineness, in order to satisfy softness, a sense of lightness and durability simultaneously, it is necessary to increase the strength, and in order to maintain high-order passability and product quality, it is necessary to have an appropriate elongation. Also, in order to improve high-order passability and product quality, it is necessary to suppress the generation of hairiness and tarry. Therefore, the present inventors have intensively studied and found an appropriate range of fineness, strength, elongation, and the number of hairiness and tarry that are excellent in high-order passability, product quality, and product durability, and have excellent softness and a sense of lightness, and can realize a woven or knitted fabric.

[0017] The polyamide multifilament of the present invention is characterized in that the total fineness is 56 dtex or less. By setting it within such a range, the woven or knitted fabric is excellent in softness and a sense of lightness. More preferably, it is 44 dtex or less.

[0018] The polyamide multifilament of the present invention has a strength of 7.0 cN / dtex or more. By setting it within such a range, the durability of the woven or knitted fabric reaches a level that can withstand actual use. Also, although the greater the strength, the more preferable, the upper limit value in the present invention is about 8.0 cN / dtex.

[0019] The polyamide multifilament of the present invention has an elongation of 33 to 50%. By setting it within such a range, yarn breakage in high-order processing steps is reduced, and high-order passability and product quality are improved. In particular, it is excellent in high-order passability when knitting and weaving at high speed. When the elongation is less than 33%, yarn breakage in high-order processing steps such as the fabric manufacturing process (warping process, weaving process) and the knitted fabric manufacturing process (warping process, knitting process) increases, and high-order passability deteriorates. The dimensional stability of the woven or knitted fabric decreases, and the product quality decreases. When the elongation exceeds 50%, the strength decreases, and the durability (burst strength, tear strength) of the woven or knitted fabric decreases. More preferably, it is 35 to 45%.

[0020] The polyamide multifilament of the present invention has 1 or less hairiness and tarumi per 100,000 m. If it is more than 1, in the weaving and knitting processes, the hairiness and tarumi parts will get caught on reeds and needles, increasing yarn breakage and deteriorating high-order permeability. Also, due to the tension change caused by the hairiness and tarumi parts getting caught on reeds and needles, streakiness defects are induced and the product quality becomes inferior.

[0021] The polyamide multifilament of the present invention preferably has a dry heat shrinkage rate at 180°C of 12.0% or less. 180°C is a general temperature for dimension stabilization setting of woven and knitted fabrics using polyamide multifilaments, and the dry heat shrinkage rate at this temperature indicates the degree of shrinkage of filaments occurring in the woven and knitted fabric manufacturing process. By setting it to 12.0% or less, the dimensional stability of the woven and knitted fabric can be obtained and suppression of sink mark defects becomes possible.

[0022] The cross-sectional shape of the polyamide multifilament of the present invention is not particularly limited, and for example, a round cross-section, a flat cross-section, a lens-shaped cross-section, a multi-lobed cross-section, a hollow cross-section, or other known non-circular cross-sections may be used.

[0023] The polyamide multifilament of the present invention preferably has 3 or more filaments. The upper limit value is preferably 144 or less filaments when the total fineness is 56 dtex, and 27 or less filaments when the total fineness is 11 dtex.

[0024] The polyamide multifilament of the present invention preferably has a single filament fineness of 0.4 to 10 dtex. As the single filament fineness becomes finer, the softness of clothing woven and knitted fabrics increases, but pilling is likely to occur due to rubbing or the like, and the durability of the product decreases. By setting it within such a range, woven and knitted fabrics excellent in softness and durability can be obtained.

[0025] Next, an example of a method for manufacturing polyamide multifilaments according to the present invention will be specifically described. Figure 1 shows an embodiment of a manufacturing apparatus for the direct spinning and drawing method, which is preferably used in the method for manufacturing polyamide multifilaments according to the present invention. In the production of polyamide multifilaments according to the present invention, a polyamide resin is melted, the polyamide polymer is measured and transported by a gear pump, and finally extruded from an extrusion hole provided in a spinneret 1 to form each filament. Each filament extruded in this manner from the spinneret 1 is cooled and solidified to room temperature by a cooling device 4, which is equipped with a gas supply device 2 that blows steam to suppress soiling of the spinneret over time, as shown in Figure 1, and a multi-layer heating cylinder 3 that surrounds the entire circumference for slow cooling. After that, an oiling device 5 is used to apply oil and to gather each filament to form a multifilament, which is then entangled by a fluid entanglement nozzle device 6, passes through a take-up roller 7 and a drawing roller 8, and is drawn according to the ratio of the peripheral speeds of the take-up roller 7 and the drawing roller 8. Furthermore, the yarn is heat-treated by heating the stretching roller 8 and then wound up by the winding device 9.

[0026] The polyamide multifilament of the present invention has a sulfuric acid relative viscosity of the polyamide polymer used in melt spinning of 2.5 to 4.0, a melting temperature of melt spinning set to be 20°C higher and 85°C lower than the melting point of the polyamide, and the temperature of the gas supply device and heating cylinder set to 250°C or higher to maintain a high ambient temperature below the die, and the cooling start distance LS set to 100 to 180 mm to slowly cool the polyamide polymer coming out of the discharge hole below the die, and convergence is imparted by blowing compressed air and the degree of entanglement before stretching. The product can be preferably manufactured by setting the (CF value) to 20-50, the take-up roller speed to 700-1500 m / min, the stretching ratio to 3.0-3.5 times, setting the stretch roller temperature to a temperature 35°C lower or more and 15°C lower or less than the polymer melting point in order to fix the highly oriented crystal structure formed by stretching, and setting the tension between the stretch roller and the winding device (winding tension) to 0.15-0.20 cN / dtex in order to improve the separation between the stretch roller and the filament and suppress fluffing and sagging.

[0027] In the production of polyamide multifilaments according to the present invention, the sulfuric acid relative viscosity of the polyamide resin is preferably 2.5 to 4.0. By setting it within this range, a polyamide multifilament with high strength can be obtained.

[0028] In the production of polyamide multifilaments of the present invention, a heating cylinder 3 is provided above the cooling device 4 so as to surround each filament all around. By installing the heating cylinder 3 above the cooling device 4 and setting the ambient temperature inside the gas supply device and heating cylinder to 250°C or higher, the orientation of the polyamide polymer extruded from the spinneret 1 can be relaxed. This relaxation of orientation due to slow cooling from the spinneret surface to the cooling stage results in a high-strength multifilament. If a heating cylinder is not installed, the relaxation of orientation due to slow cooling from the spinneret surface to the cooling stage is insufficient, making it difficult to obtain fibers with satisfactory strength.

[0029] In the production of polyamide multifilaments of the present invention, the cooling device 4 can be manufactured by any of the following methods: a cooling device that blows out cooling rectified air from a certain direction, an annular cooling device that blows out cooling rectified air from the outer circumference towards the center, or an annular cooling device that blows out cooling rectified air from the center towards the outer circumference. The vertical distance LS (cooling start distance LS) from the lower surface of the spinneret to the upper end of the cooling air outlet of the cooling device 4 is preferably in the range of 100 to 180 mm. By making the cooling start distance LS 100 mm or longer, orientation relaxation is promoted and fibers that satisfy the strength can be obtained, and by making it 180 mm or less, yarn sway can be suppressed and productivity can be ensured. More preferably, it is 110 to 170 mm.

[0030] In the manufacturing of polyamide multifilaments according to the present invention, the convergence of the running multifilaments before the take-up roller 7 is enhanced. By providing sufficient convergence, untwisting of convergence is suppressed even after drawing, the ability of the running multifilaments to separate from the drawing roller 8 is improved, which not only suppresses fuzzing and sagging but also prevents the filaments from being caught in the drawing roller and breaking. In particular, as the total fineness decreases, it becomes necessary to reduce the appropriate tension, so the filaments are more likely to be caught in the drawing roller 8 and more likely to cause fuzzing and sagging. To increase convergence, entanglement is introduced in the fluid entanglement nozzle device 6 before the take-up roller 7, and the pre-drawn entanglement degree (CF value) is controlled to 20 to 50. The entanglement degree here is measured using an automatic entanglement degree tester (ENTANGLEMENT TESTERR-2040 manufactured by Rothschild) which has performance equivalent to that of the method described in JIS L1013, on a sample of multifilaments collected by winding the running multifilaments around the take-up roller 7. Specifically, the measurement speed was set to 2.5 m / min, the trip tension level to 1.2 cN / dtex, and the thread length between trips to the next needle insertion was 20 mm. The number of repeated measurements was 50, and the sample was measured continuously. The length of the opened fibers (mm) from the needle insertion point on the measurement thread until the trip tension level (1.2 cN / dtex) was reached and the thread tripped was measured. The degree of entanglement (number of entanglements per meter) was defined as 50,000 (mm) divided by the total length of the opened fibers (mm) measured over 50 trips.

[0031] To control the degree of entanglement within a given range, the design of the fluid entanglement nozzle device and the method of controlling the fluid ejection pressure in the fluid entanglement nozzle device are useful. For example, by setting the ejection pressure to 0.3 to 0.4 MPa, the degree of entanglement can be controlled to 20 to 50. Setting the degree of entanglement to 20 or higher improves convergence, enhances the ability of the filament to separate from the stretching roller, suppresses fluffing and sagging, and reduces the number of fluffs and sagging particles per 100,000 m to 1 or less. It also suppresses yarn breakage caused by the filament being caught in the stretching roller. Setting the degree of entanglement to 50 or lower reduces damage caused by entanglement pressure, and in particular, as the total fineness and single filament fineness decrease, damage to the filament increases, so suppressing the decrease in strength allows for the achievement of a strength of 7.0 cN / dtex. It also suppresses yarn breakage caused by damage to the filament due to compressed air pressure. A more preferable value is 30 to 45.

[0032] In the production of the polyamide multifilament of the present invention, it is preferable to perform single-stage stretching. When the elongation is 33-50%, it can be appropriately adjusted by the stretching ratio, but as fineness and single-fiber fineness are progressing, single-stage stretching suppresses friction between the running multifilament and the stretching roller under low tension, thereby preventing damage to the filament and preventing a decrease in strength.

[0033] Therefore, in order to achieve the strength of 7.0 cN / dtex or more, elongation of 33-50%, and one or fewer fluffs / slacks per 100,000 m as defined in this invention, an appropriate draw ratio of 3.0 to 3.5 times is preferable in single-stage drawing. A draw ratio of 3.0 times or more provides high strength, while a draw ratio of 3.5 times or less provides appropriate elongation and results in a polyamide multifilament with suppressed fluffing and slack. Preferably, it is 3.1 to 3.4 times.

[0034] In the production of the polyamide multifilament of the present invention, the heat setting treatment is performed by bringing the yarn into contact with a heating element after drawing. As an example in the direct spinning and drawing method, a heating element is provided inside the drawing roller, and a method of heat setting the yarn held (in contact) by the drawing roller is preferably used. The heat setting temperature (temperature of the drawing roller) is preferably 35°C or higher and 15°C or lower than the melting point of the polyamide resin. For example, if the melting point of the polyamide resin used in the polyamide multifilament of the present invention is 225°C, then 190°C ≤ heat setting temperature ≤ 210°C.

[0035] By using a temperature at least 35°C lower than the melting point of the polyamide resin, the fiber crystal structure is sufficiently fixed, achieving a strength of 7.0 cN / dtex and a dry heat shrinkage rate of 12.0% or less at 180°C. Furthermore, this suppresses winding tightness caused by the shrinkage of the multifilament after winding, preventing the product drum from becoming stuck on the winding roller.

[0036] By setting the temperature to 15°C or lower than the melting point of the polyamide resin, the friction of the polymer is suppressed, ensuring that the filaments of the running multifilament are released from the stretching rollers, suppressing fluffing and sagging, and resulting in a number of fluff or sagging particles of 1 or less per 100,000 meters.

[0037] In the production of polyamide multifilament of the present invention, the winding tension between the stretching roller 8 and the winding device 9 is set to 0.15 cN / dtex or higher. A useful method for controlling the tension between the stretching roller 8 and the winding device 9 within this range is to control the peripheral speed ratio between the stretching roller 8 and the winding roller (not shown) in the winding device. Depending on the total fineness and stretching ratio, the tension can be adjusted within this range when the stretching roller peripheral speed / winding roller peripheral speed is 1.02 to 1.08. By setting the winding tension to 0.15 cN / dtex or higher, the filament release of the running multifilament from the stretching roller 8 is ensured, reducing the occurrence of fluff and sagging, and resulting in one or fewer fluff or sagging particles per 100,000 m. Furthermore, the upper limit of the winding tension in this invention is 0.20 cN / dtex. If this value is exceeded, residual strain stress in the polymer will occur, causing the multifilament to shrink on the winding roller, resulting in tight winding. This may prevent the product drum from being removed from the winding roller, making production impossible. In particular, as the total fineness decreases, the filaments are more easily caught in the stretching roller 8, making it easier for the yarn to separate and causing fluff and slack. Therefore, it is important to control the tension within this range.

[0038] The polyamide multifilament of the present invention can be knitted and woven into a woven or knitted fabric using commonly used methods.

[0039] The knitting method for the fabric can be any of the following: warp knitted fabrics such as tricot or raschel; circular knitted fabrics such as single circular knit, double circular knit, or shaped circular knit; or weft knitted fabrics such as shaped weft knit. Furthermore, the knitting structure can be any of the following without being particularly limited: warp knitted fabrics such as half structure, back half structure, queen's cord structure, satin structure, satin net structure, power net structure, triconet structure, and other variations; or circular knitted fabrics such as jersey structure, jersey reversible structure, rib knit, interlock structure, reversible structure, and other variations.

[0040] Among the above, a balance between thinness and durability of the knitted fabric is required, and the fineness range that achieves the practical durability of the commonly used Raschel fabric is 33 dtex or higher.

[0041] For weaving textiles, common weaving structures such as plain weave, twill weave, satin weave, gauze and ro (a type of sheer fabric), dobby weave, and jacquard weave can be selected as appropriate.

[0042] Among the above, a balance between thinness and durability of the fabric is required, and the fineness range that achieves practical durability for the generally accepted plain weave is 11 dtex or higher.

[0043] The polyamide multifilament of the present invention is used in woven or knitted fabrics as raw silk. Furthermore, dyeing after fabrication, subsequent post-processing, and final setting conditions can be carried out according to known methods, and the use of acid dyes, reactive dyes, and of course the colors are not limited.

[0044] The polyamide multifilament of this invention can be used in clothing such as slips, camisoles, petticoats, shorts, tights, underpants, T-shirts, U-neck shirts, crew neck shirts, bodysuits, girdles, etc. for women's underwear; T-shirts, U-neck shirts, crew neck shirts, running shirts, underpants, tights, briefs, etc. for men's underwear; running shirts and pants, competition shirts and pants, golf shirts, tennis shirts, cycling shirts and pants, T-shirts, polo shirts, outdoor shirts, baseball undershirts, training wear, leotards, swimwear, athletic underpants, ski innerwear, speed skating wear, etc. for sportswear; and sweaters, vests, etc. for general outerwear, by appropriately selecting the fabric structure. It can also be used for materials such as gloves, supporters, sweatbands, and linings. [Examples]

[0045] The present invention will be described in more detail below with reference to examples.

[0046] A. Strength, elongation Fiber samples were measured according to JIS L1013 (2010) standards for tensile strength and elongation. The test conditions were a constant-speed tensioning machine, a gripping distance of 50 cm, and a tensile speed of 50 cm / min. If the strength at break was less than the maximum strength, the maximum strength and the elongation at that point were measured. The strength and strength-to-elongation product were calculated using the following formulas. Strength = Strength at break (cN) / Fineness (dtex) Elongation = Elongation at the time of cutting (%).

[0047] B. Fineness A fiber sample was placed in a measuring device with a circumference of 1.125 m, rotated 500 times to create a loop-shaped skein, dried in a hot air dryer (105 ± 2°C for 60 minutes), and the skein mass was weighed on a balance. The fineness (dtex) was calculated from the value multiplied by the official moisture content. The official moisture content was set at 4.5%.

[0048] C. Relative viscosity of sulfuric acid (ηr) 0.25 g of a polyamide chip sample or fiber sample was dissolved in 100 ml of 98% by mass sulfuric acid to a total volume of 1 g, and the flow time (T1) at 25°C was measured using an Ostwald viscometer. Subsequently, the flow time (T2) of 98% by mass sulfuric acid alone was measured. The ratio of T1 to T2, i.e., T1 / T2, was defined as the relative viscosity of the sulfuric acid.

[0049] D. Number of fluff / sagging areas The obtained fiber samples were rewound at a speed of 500 m / min, and a laser-type fluff detector was placed 2 mm away from the yarn during rewinding. The total number of detected defects was converted to the number per 100,000 m and displayed.

[0050] E. Dry heat shrinkage rate The measurement was performed using a "heat shrinkage unevenness measuring device" manufactured by Toray Engineering Co., Ltd. The yarn was continuously subjected to dry heat treatment in a dry heat treatment section located between the yarn feeding roller and the yarn pulling roller, and the heat-induced shrinkage rate was continuously measured. The measurement was performed for 3 minutes at a yarn feeding speed of 10 m / min and a heater temperature of 180°C, and the average value was defined as the dry heat shrinkage rate (%).

[0051] F. Degree of entanglement before stretching The target sample is obtained by wrapping the running multifilament around the take-up roller 7 and collecting it. An automated entanglement tester (Rothschild ENTANGLEMENT TESTERR-2040) with performance equivalent to the method described in JIS L1013 is used to measure and calculate the open fiber length (mm) from the needle puncture point on the measurement yarn until it reaches the trip tension level and trips, under the following setting conditions. Measurement speed: 2.5m / min Trip tension level 1.2cN Thread length until the next pincushion after the trip: 20cm Number of repeated measurements: 50 CF value = total open fiber length / 50000.

[0052] G. Winding tension Using a TENSION METER and FT-R pickup sensor manufactured by Toray Engineering Co., Ltd., the tension between the stretching roller 8 and the winding device 9 shown in Figure 1 was measured and converted to a unit fineness value (cN / dtex).

[0053] H. Evaluation of knitted products (a) Process passability The number of times the knitting machine stopped due to yarn breakage when knitting 10 bolts (1000m / bolt) in a power net structure using a Raschel knitting machine (28 gauge) with a blend of 77% of the yarn of the present invention and 23% of 140d polyurethane was evaluated according to the following criteria. S: Less than 2 times A: More than 2 times but less than 4 times B: 4 times or more but less than 6 times C: 6 or more times S and A were considered acceptable for passing the process.

[0054] (b)Durability The bursting strength was measured and used as an indicator of durability. The bursting strength of the knitted fabric was measured according to JIS L1096(2010) Method A and the Mullen method. Three measurements were taken, and the average value was evaluated on a four-point scale according to the following criteria. S:300kPa or more A: 280kPa or more and less than 300kPa B: 260kPa or more and less than 280kPa C: Less than 260kPa S and A were designated as durability standards.

[0055] (c) Product quality The degree of unevenness and streaking in 50 meters of knitted fabric was evaluated by visual inspection according to the following criteria. S: It has no streaks or unevenness and possesses excellent quality. A: There are slight streaks and inconsistencies, but it does not affect the product's usability. C: Streaks and unevenness are present, making it unsuitable for use as a product. S and A were deemed to have passed the visual inspection of the fabric.

[0056] I. Evaluation of Textile Products (a) Process passability The number of times the loom stopped due to yarn breakage while weaving 10 bolts (1000m / bolt) of plain weave fabric on a waterjet loom at a loom rotation speed of 750 rpm and a weft length of 1620 mm was evaluated according to the following criteria. S: Less than 2 times A: More than 2 times but less than 4 times B: 4 times or more but less than 6 times C: 6 or more times S and A were considered acceptable for passing the process.

[0057] (b)Durability Tear strength was measured and used as an indicator of durability. Tear strength was measured in accordance with JIS L1096 (2010) tensile strength, single tang method (Method A) for the fabric. The tear strength in the warp direction was measured three times, and the average value was evaluated on a four-point scale according to the following criteria. S: 6.0N or more A: 5.0N or more and less than 6.0N B: 4.0N or more and less than 5.0N C: Less than 4.0N S and A were designated as durability standards.

[0058] (c) Product quality The degree of unevenness and streaking in the fabric was evaluated by visual inspection using the following criteria per 50 meters of fabric. S: It has no streaks or unevenness and possesses excellent quality. A: There are slight streaks and inconsistencies, but it does not affect the product's usability. C: Streaks and unevenness are present, making it unsuitable for use as a product. S and A were deemed to have passed the visual inspection of the fabric.

[0059] [Example 1] (Manufacturing of polyamide multifilaments) As the polyamide, nylon 6 chips with a sulfuric acid relative viscosity (ηr) of 3.3 and a melting point of 225°C were dried by conventional methods to a moisture content of 0.03% by mass or less. The obtained nylon 6 chips were melted at a spinning temperature (melting temperature) of 298°C and extruded from a spinneret (extrusion rate: 41.68 g / min). The spinneret used had 20 holes, was round, had a hole diameter of φ0.25, and produced 4 filaments per spinneret.

[0060] After being extruded from the spinneret, the yarn was cooled and solidified to room temperature by passing it through a cooling device with 18°C ​​cold air. It was then lubricated and converged using a lubrication device, and entangled with a entanglement CF value of 35 using a fluid entanglement nozzle device. The yarn was then stretched at a draw-up roller (first goded roll: 1GD) at a speed of 1000 m / min and through a drawing roller (second goded roll: 2GD) heated to 195°C, with a stretch ratio of 3.3 times. The yarn was then wound at a winding speed of 3200 m / min and a winding tension of 0.18 cN / dtex to obtain a nylon 6 multifilament of 33 dtex and 5 filaments. The results of the evaluation of the obtained nylon 6 multifilament are shown in Table 1.

[0061] (Knitwear manufacturing) The obtained multifilaments were warped in groups of 576 and wound onto a beam. The yarn wound on the beam was then aged to prepare the warp. Next, using a 28G Raschel knitting machine, the obtained multifilaments were mixed with 23% 140d polyurethane in a power net structure and knitted. The raw fabric was then scouring, dyed, and finished at 180°C to obtain a Raschel knit fabric for innerwear. The results of the evaluation of the obtained knit fabric are shown in Table 1.

[0062] [Examples 2 and 3] [Comparative Examples 1 and 2] Except for changing the degree of entanglement before stretching by adjusting the compressed air pressure as shown in Tables 1 and 2, a 33 dtex, 5-filament nylon 6 multifilament was obtained using the same method as in Example 1. The evaluation results are shown in Tables 1 and 2.

[0063] [Example 4] A 33dtex, 5-filament nylon 6 multifilament was obtained using the same method as in Example 1, except that the extrusion rate was changed to 37.26 g / min, the stretching ratio to 3.0 times, and the winding speed to 2950 m / min. The evaluation results are shown in Table 1.

[0064] [Example 5] Except for changing the extrusion rate to 42.32 g / min, the stretching ratio to 3.5 times, and the winding speed to 3350 m / min, a 33 dtex, 5-filament nylon 6 multifilament was obtained using the same method as in Example 1. The evaluation results are shown in Table 1.

[0065] [Comparative Example 3] Except for changing the extrusion rate to 36.25 g / min, the stretching ratio to 2.9 times, and the winding speed to 2870 m / min, a 33 dtex, 5-filament nylon 6 multifilament was obtained using the same method as in Example 1. The evaluation results are shown in Table 2.

[0066] [Comparative Example 4] Except for changing the extrusion rate to 43.33 g / min, the stretching ratio to 3.6 times, and the winding speed to 3430 m / min, a 33 dtex, 5-filament nylon 6 multifilament was obtained using the same method as in Example 1. The evaluation results are shown in Table 2.

[0067] [Example 6] Except for changing the winding speed to 3180 m / min and the winding tension to 0.15 cN / dtex, a nylon 6 multifilament with 33 dtex and 5 filaments was obtained using the same method as in Example 1. The evaluation results are shown in Table 1.

[0068] [Example 7] Except for changing the winding speed to 3220 m / min and the winding tension to 0.20 cN / dtex, a 33 dtex, 5-filament nylon 6 multifilament was obtained using the same method as in Example 1. The evaluation results are shown in Table 1.

[0069] [Comparative Example 5] Except for changing the winding speed to 3160 m / min and the winding tension to 0.13 cN / dtex, a nylon 6 multifilament with 33 dtex and 5 filaments was obtained using the same method as in Example 1. The evaluation results are shown in Table 2.

[0070] [Examples 8 and 9] [Comparative Examples 6 and 7] A 33dtex, 5-filament nylon 6 multifilament was obtained using the same method as in Example 1, except that the temperature of the stretching roller was changed as shown in Table 1. The evaluation results are shown in Tables 1 and 2.

[0071] [Example 10] A nylon 6 multifilament with 56 dtex and 24 filaments was obtained using the same method as in Example 1, except that the extrusion rate was 49.84 g / min, the number of holes was 72, the shape was round, the hole diameter was φ0.25, and 3 filaments / die was used, the stretching ratio was 3.3 times, the stretching roller temperature was 200°C, the winding speed was 3100 m / min, and the winding tension was changed to 0.16 g / dtex. The evaluation results are shown in Table 1.

[0072] [Comparative Example 8] In Patent Document 1, using the process shown in Figure 1 (two-stage stretching), a 33dtex, 5-filament nylon 6 multifilament was obtained in the same manner as in Example 1, except that the extrusion rate was 41.86g, the peripheral speed ratio of the take-up roller to the first stretching roller was 2.65 for the first stretching stage, the peripheral speed ratio of the first stretching roller to the second stretching roller was 1.25 for the second stretching stage, the overall stretching ratio was 3.3 times, and the winding speed was changed to 3200m / min. The evaluation results are shown in Table 2.

[0073] [Table 1]

[0074] [Table 2]

[0075] [Example 11] A nylon 6 multifilament with 11 dtex and 8 filaments was obtained using the same method as in Example 1, except that the extrusion rate was 19.20 g / min, the number of holes was 48, the shape was round, the hole diameter was φ0.20, and 6 filaments / die was used, the stretching ratio was 3.2 times, the winding speed was 3040 m / min, and the winding tension was changed to 0.2 cN / dtex. The evaluation results are shown in Table 3.

[0076] (Textile manufacturing) The obtained multifilaments were warped in batches of 1000 and wound onto a beam. The threads wound on the beam were then sizing and dried to prepare the warp threads. Next, the multifilaments were passed through a waterjet loom reed and woven into the weft threads. The woven fabric was then scouring, heat-set at 180°C (intermediate set), dyed, and calendered at 180°C to obtain a fabric for outdoor jackets. The results of the evaluation of the obtained fabric are shown in Table 3.

[0077] [Comparative Example 9] Except for changing the winding speed to 3160 m / min and the winding tension to 0.13 g / dtex, a nylon 6 multifilament with 11 dtex and 8 filaments was obtained using the same method as in Example 11. The evaluation results are shown in Table 3.

[0078] [Comparative Example 10] Except for changing the temperature of the stretching roller to 180°C, a nylon 6 multifilament of 11 dtex and 8 filaments was obtained using the same method as in Example 11. The evaluation results are shown in Table 3.

[0079] [Table 3] [Explanation of Symbols]

[0080] 1: Spinner 2: Gas supply device 3: Heating cylinder 4: Cooling device 5: Fueling device 6: Fluid entanglement nozzle device 7: Pickup roller 8: Stretching roller 9: Winding device

Claims

1. A polyamide multifilament having a strength of 7.0 cN / dtex or higher, elongation of 35-45%, total fineness of 56 dtex or less, dry heat shrinkage at 180°C of 12.0% or less, and one or fewer fluffs / slacks per 100,000 meters.

2. A woven or knitted fabric comprising polyamide multifilaments as described in claim 1.

3. A method for producing polyamide multifilaments by direct filament stretching, comprising melting a polyamide resin, cooling and solidifying each filament extruded from a spinneret, lubrication and entanglement treatment, and then stretching and heat-treating them using rollers of different peripheral speeds and winding them up, The method for producing a polyamide multifilament according to claim 1, characterized in that it satisfies the following conditions (A) to (D). (A) Pre-extension confounding degree is 20-50, (B) Extension ratio is 3.0 to 3.5, (C) The heat setting temperature is 35°C lower or more than the melting point of the polyamide resin and 15°C lower or less than the melting point of the polyamide resin. (D) The winding tension between the stretching roller and the winding device is 0.15 to 0.20 cNdtex

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