Polyester thick and thin multifilament

Abstract

To provide a designable woven and knitted fabric which, when made into a dyed woven or knitted fabric, has excellent clarity of grandrelle tone, has a sharp contrast of dark and light developed by a deeply dyed part and a lightly dyed part, and also has a soft feeling.SOLUTION: A cation dyeable polyester thick and thin multifilament, which contains 0.6-2.5 mol% of an isophthalic acid component having a metal sulfonate group in the total dicarboxylic acid of polyester, has 0.40-1.2 dtex of single fiber fineness, and has 3-17 / m of an average value of the number of fineness variation peaks having 40% or more (N40) of fineness variation rate width from the fineness variation baseline of Uster wave form, has 1.8-2.5 cN / dtex of breaking strength, 19.0 or more of toughness, 5-16% of Uster thick and thin unevenness derived from fineness unevenness in a multifilament longitudinal direction, and 12% or less of variation coefficients CV% of the number of fineness variation peaks having 20% or more (N20) of fineness variation rate width from the fineness variation baseline of the Uster wave form.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyester thick-thin multifilament having thickness variations in the yarn longitudinal direction, capable of expressing a mottled look with a large contrast between light and dark shades, and capable of giving woven or knitted fabrics having a soft feel. [Background technology]

[0002] In recent years, there has been a growing need for woven and knitted fabrics with excellent design for sportswear and interior use, and there is an expanding demand for heathered materials with high contrast between light and dark, rich design potential, and a soft texture.

[0003] As a representative multifilament of a heathered material, it is a known technique to non-uniformly draw a highly oriented, undrawn polyester multifilament to produce a multifilament having thickness and thinness in the longitudinal direction of the yarn. The thick and thin multifilament obtained in this way has a heathered appearance due to the difference in dyeing shade resulting from the thickness and thinness, and is used for woven and knitted clothing applications such as outerwear and casual wear for women and men, as well as for interior applications (Patent Document 1).

[0004] On the other hand, in order to improve the color development of polyester multifilaments, ionic dyeing sites, such as isophthalic acid components containing metal sulfonate groups, are copolymerized to obtain thick and thin polyester multifilaments that can be dyed with cationic dyes with excellent color development (Patent Documents 2 to 5).

[0005] Also, a method of blending polyester and nylon and dyeing them differently has been proposed (Patent Document 6). According to this method, polyester and nylon are blended and stretched at a temperature below the two-time transition temperature to form thick and thin spots, resulting in differences in dyeing density and in multiple colors due to dyeing with different dyes, thereby making it possible to obtain polyester multifilaments with a wide range of designs. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 50-18717 [Patent Document 2] Japanese Patent Application Publication No. 2018-162531 [Patent Document 3] Japanese Patent Application Laid-Open No. 2003-306830 [Patent Document 4] Japanese Patent Application Laid-Open No. 2006-200064 [Patent Document 5] Japanese Patent Application Laid-Open No. 2004-277956 [Patent Document 6] Japanese Patent Application Publication No. 55-158329 Summary of the Invention [Problem to be solved by the invention]

[0007] However, although the mottled tones obtained by the methods described in Patent Documents 2 to 5 have excellent color clarity, highly oriented, undrawn multifilaments using only polymers copolymerized with ionic dyeing sites, such as isophthalic acid components containing metal sulfonate groups, have a short constant stress elongation range elongation, and when non-uniformly drawn in the subsequent drawing process, the difference in fiber diameter between the thick and thin portions becomes small. This effect is more pronounced in highly oriented, undrawn multifilaments with low single yarn fineness. Therefore, although the obtained cationic dyeable polyester thick-thin multifilaments have excellent color clarity, the obtained mottled tones have low contrast between light and dark, weakening their characteristics as decorative materials.

[0008] In addition, the fiber described in Patent Document 6 is produced by melt-spinning a blend of polyester and nylon, and then drawing at a low temperature below the secondary transition point to form thick and thin patterns. Because the blending of polyester and nylon reduces the strength of the highly oriented, undrawn multifilament, spinnability is particularly poor when the single-fiber fineness is low, resulting in frequent single-fiber breakage during spinning and making spinning difficult. Furthermore, to avoid yarn breakage and single-fiber breakage during drawing, drawing must be performed at a low ratio. As a result, the difference in fiber diameter between the thick and thin portions is insufficient, resulting in a low contrast between light and dark tones in the resulting figured pattern. The present invention aims to provide a polyester thick-thin multifilament yarn which has excellent processability, has thickness and thinness in the yarn longitudinal direction, can express a mottled look with a large contrast in shade, and can give woven or knitted fabrics having a soft texture. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention employs the following configuration. (1) A polyester thick / thin multifilament containing 0.6 to 2.5 mol % of an isophthalic acid component containing a metal sulfonate group relative to the total dicarboxylic acid of the polyester, and satisfying the following A and B: A. Single yarn size: 0.40 to 1.2 dtex B. The average number of peaks (N40) of fineness fluctuations in the Worcester waveform resulting from unevenness in the longitudinal direction of the multifilament, with a width of 40% or more from the baseline, is 3 to 17 peaks / m. (2) The polyester thick / thin multifilament according to (1), characterized in that it has a breaking strength of 1.8 to 2.5 cN / dtex and a toughness of 19.0 or more. (3) A polyester thick / thin multifilament according to (1), characterized in that the Worcester thick / thin unevenness resulting from unevenness in the lengthwise direction of the multifilament is 5 to 16%. (4) The polyester thick / thin multifilament according to (1), characterized in that the coefficient of variation CV% of the number of fineness fluctuation peaks (N20) with a fineness fluctuation rate width of 20% or more from the fineness fluctuation baseline of the Worcester waveform resulting from fineness unevenness in the longitudinal direction of the multifilament is 12% or less. [Effects of the Invention]

[0010] The cationic dyeable polyester thick / thin multifilament of the present invention provides woven or knitted fabrics that have good color clarity when dyed, a large contrast between the darkly dyed and lightly dyed parts in a mottled tone, and a soft texture. [Brief explanation of the drawings]

[0011] [Figure 1] SS curve to explain constant stress elongation region elongation (NDR elongation) [Figure 2] FIG. 1 is an explanatory diagram showing a schematic diagram of a non-uniform stretching device used in the examples. [Figure 3] Worcester waveform chart and fineness fluctuation peak DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below.

[0013] The main component of the polyester of the present invention is polyethylene terephthalate obtained by esterifying or transesterifying terephthalic acid or its ester-forming derivative and ethylene glycol or its ester-forming derivative.

[0014] The content of the isophthalic acid component (SI component) containing a metal sulfonate group in the polyester thick / thin multifilament of the present invention is 0.6 to 2.5 mol % based on the total carboxylic acid components. If the SI component content is less than 0.6 mol%, sufficient color clarity cannot be obtained, and the mottled tone also has a low contrast between light and dark. If the SI component content exceeds 2.5 mol%, the multifilament is dyed uniformly regardless of its thick and thin spots, making the mottled tone less noticeable and reducing the mechanical properties (strength, etc.) of the multifilament. The SI component content is preferably 1.0 to 2.0 mol%.

[0015] The polyester thick / thin multifilament of the present invention has a mean value of fineness fluctuation peaks (N40) at which the fineness fluctuation range from the baseline of the fineness fluctuation rate in a Worcester waveform chart is 40% or more, in the longitudinal direction of the multifilament, of 3 to 17 peaks / m, preferably 5 to 17 peaks / m. If the mean value of N40 is less than 3 peaks / m, the difference in shade of dyeing is insufficient, and a clear mottled effect cannot be obtained. If the mean value of N40 is more than 17 peaks / m, the darkly dyed portions become dominant, and the entire fabric appears darkly dyed, making it impossible to obtain a clear mottled effect.

[0016] The polyester thick / thin multifilament of the present invention has a single yarn fineness of 0.40 to 1.2 dtex. It is more preferably 1.0 dtex or less, and even more preferably 0.8 dtex or less. If the single yarn fineness is less than 0.4 dtex, the dark-dyed and light-dyed parts will be finely dispersed, making it difficult to visually recognize the heathered pattern, and a clear heathered pattern cannot be obtained. If it exceeds 1.2 dtex, the bending rigidity will increase when made into a fabric, making it impossible to obtain a soft feel.

[0017] In a preferred embodiment of the polyester thick / thin multifilament of the present invention, the breaking strength is 1.8 to 2.5 cN / dtex. By setting the breaking strength within this range, the yarn can be easily passed through post-processing steps, and when dyed into a woven or knitted fabric, the contrast between light and dark hues of the heathered pattern is good.

[0018] The toughness of the polyester thick / thin multifilament of the present invention is preferably 19.0 or more, and more preferably 20.0 or more. The toughness T is expressed by the following formula, where ScN / dtex is the strength of the multifilament and E% is the elongation. T=S×E 1 / 2 If the toughness is 19.0 or more, the fabric strength when made into a woven or knitted fabric is at a level suitable for clothing applications, and the high-level processability is good.

[0019] The polyester thick-thin multifilament of the present invention preferably has a Worcester thick-thin unevenness resulting from unevenness in the lengthwise direction of the multifilament of 5 to 16%. By controlling the Worcester thick-thin unevenness in this range, a clear figured tone can be obtained when the fabric is made. In addition, localization of thick portions showing dark-dyed portions is unlikely to occur, and the dimensional stability of the woven or knitted fabric is improved.

[0020] The polyester thick / thin multifilament of the present invention preferably has a coefficient of variation (CV%) of 12% or less for the number of fineness fluctuation peaks (N20) at which the fineness fluctuation range from the baseline of the fineness fluctuation rate in a Worcester waveform chart is 20% or more, with respect to the fineness fluctuation rate in the longitudinal direction of the multifilament. It is more preferably 3 to 10%. When the CV% of N20 is 12% or less, that is, the variation in the frequency of occurrence of thick / thin spots in the longitudinal direction of the multifilament is small, and when the multifilament is made into a woven or knitted fabric, localization of thick and thin portions is unlikely to occur, resulting in a stable heathered look. Furthermore, the fabric strength and dimensional stability are also excellent.

[0021] A specific method for producing the polyester thick / thin multifilament of the present invention will be described in detail below.

[0022] The polyester thick / thin multifilament of the present invention is obtained by melt-mixing and spinning two types of polyesters with different melting points measured by DSC to obtain a highly oriented, undrawn yarn having a constant stress elongation region elongation (NDR elongation A) of 35 to 70% in the SS curve, followed by non-uniform drawing of the highly oriented, undrawn yarn using a friction resistor in a separate process.

[0023] The two polyesters used have different melting points: a polyester obtained by esterifying or transesterifying a dicarboxylic acid or its ester-forming derivative with a diol or its ester-forming derivative (hereinafter referred to as "polyester A"), and a polyester obtained by copolymerizing polyester A with an SI component as a third component (hereinafter referred to as "copolyester B"). This SI component (an isophthalic acid component containing a metal sulfonate group) is preferably 5-sodium dimethyl sulfoisophthalate. The polyester A and copolyester B may be copolymerized with a fourth component or may be made from recycled raw materials, provided that the objectives of the present invention are not exceeded. Furthermore, additives such as matting agents, pigments, dyes, antifouling agents, fluorescent brighteners, flame retardants, stabilizers, weather resistance agents, UV absorbers, lubricants, or moisture absorbers may also be added.

[0024] From the viewpoint of compatibility, it is preferable that the ratio (Pb / Pa) of the melt viscosity (Pa) of polyester A to the melt viscosity (Pb) of copolymer polyester B is 0.7 to 2.0. By setting the melt viscosity ratio within this range, the compatibility of the two polyesters is increased, and the breaking strength and toughness of the polyester thick / thin multifilament of the present invention can be maintained at a high level. Furthermore, yarn breakage is suppressed during spinning and non-uniform drawing of highly oriented undrawn yarn, resulting in excellent operability.

[0025] The blend weight ratio of polyester A to copolymer polyester B is such that the proportion of polyester A is 50% by weight or more relative to 100% by weight of the total amount of polyester A and copolymer polyester B. Preferably, it is 55 to 80% by weight. By setting the proportion of polyester A within this range, the NDR elongation A can be maintained for a long time, and when non-uniformly stretched in the subsequent stretching step, the difference in fiber diameter between the thick and thin portions becomes large, resulting in a high contrast between shades and a clear figured tone. On the other hand, if the proportion of polyester A is less than 50%, the NDR elongation A becomes short, and when non-uniformly stretched in the subsequent stretching step, the difference in fiber diameter between the thick and thin portions becomes small, resulting in a low contrast between shades and a clear figured tone cannot be obtained, which is undesirable.

[0026] Methods for melt-kneading and mixing polyester A and copolymer polyester B include a method in which the two types of polyester polymers are melted separately and then melt-kneaded in a mixer, and a method in which the two types of polyester polymers are mixed in chip form and then melted.

[0027] Furthermore, by using a combination of these methods, it is possible to realize a compatible system in which copolymer polyester B is evenly dispersed throughout the multifilament, resulting in a highly oriented undrawn yarn with an NDR elongation A of 35 to 70% on the SS curve. The polyester thick-thin multifilament obtained by non-uniformly drawing the highly oriented undrawn yarn can have an average value of the fineness fluctuation peak (N40) within a desired range. Furthermore, high breaking strength and toughness can be maintained. More specifically, polyester A and copolymer polyester B are each chipped, weighed, and mixed, then melt-kneaded using an extruder, and further stirred and mixed using a piping mixer. The SS curve behavior of the fiber obtained by melt-kneading and mixing the two polymers, polyester A and copolymer polyester B, in the above ratio has a longer NDR elongation A than the SS curve of the highly oriented undrawn yarn of copolymer polyester B alone, and is closer to the SS curve of the highly oriented undrawn yarn of polyester A alone. Therefore, when the fabric is stretched unevenly in the subsequent stretching process, the difference in fiber diameter between the thick and thin parts becomes large, resulting in a large contrast in shade and a clear mottled look.

[0028] Furthermore, because the NDR elongation A shifts to a shorter value as the single yarn fineness decreases, the NDR elongation A does not appear in the SS curve or the region is very narrow even for highly oriented, undrawn yarns with a low single yarn fineness made solely of copolymer polyester B. However, by using two types of polymer, polyester A and copolymer polyester B, the NDR elongation A of highly oriented, undrawn yarns can be maintained for a long time even with a low single yarn fineness, and when unevenly drawn in the subsequent drawing process, the difference in fiber diameter between the thick and thin parts becomes large, resulting in a high contrast between light and dark areas and a clear figured tone.

[0029] In the melt kneading, it is preferable to knead the materials firmly using an extruder, and this can be carried out by a known method such as using a single-screw or double-screw extruder.

[0030] The piping mixer used for stirring and mixing after melt kneading is preferably one that repeatedly applies position change and dividing actions to the transported material, and the shape of the element installed in the piping to apply the position change and dividing actions can be known, but it is preferable to divide and change positions five or more times, as this will enable the two types of polyester polymers to be stirred and mixed firmly.

[0031] Melt spinning can be carried out by a conventionally known method, namely, by melting a polyester polymer at a temperature of 275 to 300°C, discharging the melt from a spinneret, blowing cooling air onto the melt to form a filament, converging the filament, adding an oil to entangle the filament, and winding the filament into a package to wind up a highly oriented, undrawn multifilament.

[0032] The highly oriented undrawn yarn of the present invention is preferably spun at a spinning speed of 2000 to 3200 m / min. A spinning speed of 2000 m / min or higher ensures that the strength of the drawn thick / thin multifilaments reaches a practical level, which is advantageous from the viewpoint of productivity. Furthermore, a spinning speed of 3200 m / min or lower results in the NDR elongation A shown in Figure 1, which reduces the occurrence of thick / thin variations in the longitudinal direction of the multifilaments during the drawing process.

[0033] When producing the highly oriented undrawn yarn of the present invention, oiling is carried out using an oiling guide. The amount of spinning oil applied to the highly oriented undrawn yarn is preferably 0.7 to 1.6% by mass. The oiling method is not particularly limited as long as it is a method for applying oil to a melt-spun highly oriented undrawn yarn, such as an oiling guide or an oiling roller. By setting the amount of spinning oil applied within this range, it is possible to prevent a decrease in breaking strength and toughness due to friction with the equipment, and since scum deposition on the yarn running parts of the equipment is reduced and volatilized oil does not adhere excessively to the friction resistor, the surface condition of the friction resistor is stabilized and variation in the frequency of occurrence of thick and thin spots in the longitudinal direction of the multifilament is reduced.

[0034] The polyester thick-thin multifilament of the present invention is obtained by non-uniformly drawing the highly oriented undrawn yarn at a predetermined drawing ratio using a friction resistor. The non-uniform drawing step can be carried out continuously with the spinning step, but since the highly oriented undrawn yarn immediately after spinning does not have a clear constant stress elongation region elongation shown by A in Figure 2, it is difficult to form thick-thin multifilaments even if it is non-uniformly drawn. Therefore, it is preferable to first wind up the highly oriented undrawn yarn and then non-uniformly draw it.

[0035] Fig. 2 shows one embodiment of a preferred apparatus for producing non-uniformly drawn yarn that can be used in the present invention. In Fig. 2, highly oriented undrawn yarn 1 is drawn at a low ratio between feed roller 2 and drawing roller 4 via friction resistor 3 to form thick and thin multifilaments, which are then wound on winder 6.

[0036] The friction resistor is preferably a cylindrical heat pin. By winding the highly oriented undrawn yarn around the cylindrical heat pin, the friction resistor can stably hold the running yarn, and the stick-slip phenomenon can be stabilized, thereby reducing the variation in the frequency of thick and thin spots in the longitudinal direction of the multifilament, and a clear mottled grain can be obtained.

[0037] The draw ratio is determined by the speed ratio between the feed roller 2 and the stretching roller 4. To achieve stable thick-thin variations, the draw ratio is preferably determined according to the following formula (2) such that 0.80≦α≦1.10. The NDR elongation refers to part A in Figure 1. When α is 1.10 or less, the frequency of thick portions becomes favorable, and when the fabric is dyed, the dark-dyed portions become prominent, resulting in the desired figured finish. Furthermore, when α is 0.80 or more, the strength and toughness of the thick-thin multifilament are at a practical level, and there is little occurrence of yarn breakage during advanced processing. (1+constant stress elongation region elongation A(%) / 100)×α times... (2) (α: coefficient in stretching ratio) Furthermore, the polyester thick / thin multifilament of the present invention may be heat-set using a heated roller or the like after being non-uniformly drawn, within the scope of the present invention.

[0038] The cross-sectional shape of the filaments constituting the polyester thick / thin multifilament is not particularly limited, and any shape such as a round cross section, a triangular cross section, an oval cross section, or a multi-lobed cross section can be preferably used. [Example]

[0039] The present invention will be described in more detail below with reference to examples. The respective property values ​​in the examples were determined by the following methods.

[0040] (1) Measurement of isophthalic acid components with metal sulfonate groups The chips and fiber samples were analyzed for elements using an X-ray fluorescence analyzer (ZSX-100e, manufactured by Rigaku Corporation). The amount of S element was calculated by multiplying the molecular weight of the S component.

[0041] (2) Melt viscosity The polymer chips were dried in a vacuum dryer to a moisture content of 150 ppm or less, and the melt viscosity was measured using a melt indexer (L225-41 manufactured by Tateyama Kagaku Kogyo Co., Ltd.) under the following conditions: the measurement temperature was 290°C (same as the spinning temperature), the load was 1000 g, the measurement distance was 2.54 cm, the orifice inner diameter was 0.2095 cm, the orifice length was 0.8000 cm, and the piston diameter was 0.9478 cm; and the measurement was carried out under a nitrogen atmosphere.

[0042] (3) N40 Measurement is carried out for 25 seconds using a Worster yarn evenness tester described below, and the lowest value of the fineness fluctuation rate on the obtained Worster waveform chart (corresponding to a yarn length of 10 m) is taken as the baseline (C in Figure 3). A line is drawn at a position (D in Figure 3) +40% from the baseline a, and the number of fineness fluctuation peaks having a peak top at or above line D is counted (Figure 3). The Worster waveform chart is obtained by using a Zellweger USTER TESTER UT-4 to select the measurement throttle to be used depending on the total fineness of the yarn, and then performing measurements for 1 minute under conditions of a yarn speed of 25 m / min and a twist number of 5,000 T / m.

[0043] (4) Coefficient of variation of N20 (CV%) Measurement is carried out for 25 seconds using the Worcester yarn evenness tester, and the minimum value of the fineness fluctuation rate in the obtained Worcester waveform chart (corresponding to a yarn length of 10 m) is taken as the baseline (C in Figure 3). A line is drawn at a position (E in Figure 3) +20% from the baseline a, and the number of fineness fluctuation peaks having a peak top at or above line E is counted (Figure 3). After counting the number of peaks in the 10 m yarn length, this measurement is repeated six times, and the average value and coefficient of variation CV% are calculated from the obtained number of peaks. The Worcester waveform chart is under the same conditions as above.

[0044] (5) Amount of spinning oil applied 10 g of the obtained highly oriented undrawn multifilament is precisely weighed, and the oil is extracted with 100 ml of methanol. The ratio (mass %) of the extracted amount to the highly oriented undrawn multifilament is defined as the amount (mass %) of the spinning oil applied.

[0045] (6) Total fineness and single yarn fineness The false-twisted yarn was wound 100 times on a measuring machine with a frame circumference of 1.0 m at an unwinding tension of 1 / 11.1 (g / dtex), and the weight was measured using a balance. The weight obtained by multiplying it by 100 was taken as the total fineness. The value obtained by dividing the total fineness by the number of filaments was taken as the single yarn fineness.

[0046] (7) Amount of spinning oil applied 10 g of the obtained highly oriented undrawn multifilament is precisely weighed, and the oil is extracted with 100 ml of methanol. The ratio (mass %) of the extracted amount to the highly oriented undrawn multifilament is defined as the amount (mass %) of the spinning oil applied.

[0047] (8) SS curve (breaking strength, breaking elongation, toughness, NDR elongation) Using an ORIENTEC (now A&D) TENSILON RTC-1210A, a stress-strain curve was obtained under conditions of a test length of 200 mm and a tensile speed of 200 mm / min. The strength was calculated by dividing the force at which the yarn broke by the fineness, and the elongation at which the yarn broke by dividing the sample length by 100 was calculated as the elongation. Each value was measured at three different samples, and the average was calculated. Toughness was calculated from the strength and elongation results using the formula (1) above. The constant stress elongation region elongation was calculated by reading the elongation at point A on the chart shown in Figure 3, measuring six different samples, and averaging the results.

[0048] (9) Color clarity A tubular knitted fabric with a basis weight of 150 g / m2 was made using the obtained cationic dyeable polyester thick / fine multifilament and dyed under the conditions below. The color vividness of the dyed woven / knitted fabric was visually judged by three experienced inspectors, who agreed that the color vividness was given a score of 5 points for "extremely excellent," 4 points for "excellent," 3 points for "average," 2 points for "poor," and 1 point for "no color vividness," with a score of 4 or more being considered a pass. [Dyeing conditions] Dye: Eisen Carotene Blue GLH 0.7% OWF Dyeing assistant: sodium acetate 0.15g / L ;Acetic acid (100%) 0.5mL / L Bath ratio; 1:100 Staining: After treatment at 50°C for 15 minutes, the temperature is increased at a rate of 1.6°C / min and treatment is continued at 98°C for 20 minutes.

[0049] (10) Shading Contrast The cylindrical knitted fabric prepared in (9) above was visually inspected by three experienced inspectors, who agreed that a "sufficiently large" shade contrast was given 5 points, a "large" was given 4 points, a "normal" was given 3 points, a "small" was given 2 points, and a "no shade contrast" was given 1 point, with a score of 4 or more being considered a pass.

[0050] (11) Variation in grain The cylindrical knitted fabric prepared in (9) above was visually inspected by three inspectors with more than five years of experience in quality assessment, and by consensus, the heathered pattern was given 5 points for "sufficiently dispersed," 4 points for "dispersed," 3 points for "normal," 2 points for "slightly localized," and 1 point for "localized," with a score of 4 or more being considered a pass.

[0051] (12) Soft texture The cylindrical knitted fabric prepared in (9) above was subjected to a sensory evaluation of its soft texture. Three experienced inspectors agreed to give a score of 5 for "extremely excellent" softness, 4 for "excellent," 3 for "average," 2 for "poor," and 1 for "not soft." A score of 4 or more was considered a pass.

[0052] (13) Spinning operability When the yarn breakage rate during spinning was converted to the value when produced using a four-spindle winding machine, the yarn breakage rate calculated by dividing the number of times that yarn breakage occurred by the amount of yarn spun was evaluated as follows: "less than 1.0 times" was ○○, "1.0 times or more but less than 3.0 times" was ○, "3.0 times or more but less than 5.0 times" was △, and "5.0 times or more" was ×. ○ or more is the target level.

[0053] (14) Processing operability When a 3.0 kg wound textured yarn was produced using a non-uniformly drawn yarn manufacturing device, the fill rate of the textured yarn drum was evaluated as follows: ○○ for "90% or more," ○ for "85% or more but less than 90%," △ for "80% or more but less than 85%," and × for "less than 80%." ○ or more is the target level.

[0054] (15) Advanced processing operability For the operability of advanced processing, when producing woven or knitted fabrics using cationic dyeable polyester thick / thin multifilament, the penalty rate calculated by dividing the number of yarn breakages by the number of pieces in process was marked as follows: "less than 1.0%" is ○○, "1.0% or more but less than 3.0%" is ○, "3.0% or more but less than 5.0%" is △, and "5.0% or more" is ×. ○ or above is the target level.

[0055] [Example 1] Polyester A, which does not contain an isophthalic acid component (SI component) having a metal sulfonate group, and copolymer polyester B, which contains an SI component, and which has a melt viscosity ratio (copolymer polyester B / polyester A) of 1.3 at 290°C, were weighed so that the proportion of the SI component was 1.6 mol% based on the total dicarboxylic acids. The mixture was melt-kneaded in a single-screw extruder at a kneading temperature of 284°C and mixed through a pipe mixer that was divided and changed position 12 times. The mixture was melt-spun using a spinneret with 192 holes at a spinning temperature of 290°C and a spinning speed of 2,000 m / min. After applying 0.85% by mass of spinning oil, the mixture was wound around a drum in two yarn take-up to obtain a highly oriented, undrawn yarn of 96 filaments and a total fineness of 100 dtex.

[0056] Next, the highly oriented undrawn yarn was subjected to hot pin drawing using a drawing machine as shown in Figure 1, with the temperature of hot pin 3 set to 80°C and the draw ratio set to a coefficient α of 0.95 in equation (1), and then taken up by feed roller 5 and further wound onto a bobbin by winder 6 to obtain a polyester thick / thin multifilament having 96 filaments and a total fineness of 66 dtex. The obtained polyester thick / thin multifilament had good properties as shown in Table 1.

[0057] [Examples 2 to 5] Spinning and drawing were carried out in the same manner as in Example 1, except that the blend ratio of copolymer polyester B / polyester A in Example 1 was changed and the ratio of the SI component to the total dicarboxylic acids in the yarn was changed, to obtain polyester thick / thin multifilaments. The properties of the obtained multifilaments are shown in Table 1. As shown in Table 1, the obtained polyester thick / thin multifilaments had good properties.

[0058] [Table 1]

[0059] [Examples 6 to 11] Spinning and drawing were carried out in the same manner as in Example 1, except that the proportion of the SI component contained in copolymer polyester B, the blend ratio of copolymer polyester B / polyester A, and the proportion of the SI component to the total dicarboxylic acids in the yarn were changed, to obtain polyester thick / thin multifilaments. The properties of the obtained multifilaments are shown in Table 2. As shown in Table 1, the obtained polyester thick / thin multifilaments had good properties.

[0060] [Table 2]

[0061] [Examples 12 to 15] Spinning and drawing were carried out in the same manner as in Example 1, except that the number of holes in the spinneret and the polymer discharge rate used in Example 1 were changed, to obtain polyester thick / thin multifilaments. The properties of the obtained multifilaments are shown in Table 3. As shown in Table 1, the obtained polyester thick / thin multifilaments had good properties.

[0062] [Example 16] Spinning and drawing were carried out in the same manner as in Example 1, except that the number of divisions and position changes of the piping mixer used in Example 1 was changed to 5 times, to obtain polyester thick / thin multifilaments. The properties of the obtained multifilaments are shown in Table 3. As shown in Table 1, the obtained polyester thick / thin multifilaments had good properties.

[0063] [Table 3]

[0064] [Examples 17 to 18] Spinning and drawing were carried out in the same manner as in Example 1, except that the melt viscosity ratio of the polymers used in Example 1 was changed, to obtain polyester thick / thin multifilaments. The properties of the obtained multifilaments are shown in Table 4. As shown in Table 1, the obtained polyester thick / thin multifilaments had good properties.

[0065] [Examples 19 to 20] Spinning and drawing were carried out in the same manner as in Example 1, except that the amount of spinning oil applied was changed, to obtain thick / thin polyester multifilaments. The properties of the obtained multifilaments are shown in Table 4. As shown in Table 1, the obtained polyester thick / thin multifilaments had good properties.

[0066] [Examples 21 to 22] Spinning and drawing were carried out in the same manner as in Example 1, except that the coefficient α in the draw ratio was changed, to obtain a polyester thick / thin multifilament. The properties of the obtained multifilament are shown in Table 4. As shown in Table 1, the obtained polyester thick / thin multifilament had good properties.

[0067] [Example 23] Spinning and drawing were carried out in the same manner as in Example 1, except that after non-uniform drawing in Example 1, heat setting was carried out at 90°C with a heated roller, to obtain a polyester thick / thin multifilament. The properties of the obtained multifilament are shown in Table 4. As shown in Table 1, the obtained polyester thick / thin multifilament had good properties.

[0068] [Table 4]

[0069] [Comparative Example 1] Spinning and drawing were carried out in the same manner as in Example 1, except that polyester A was not used and only copolymer polyester B, which contained an SI component in which the proportion of isophthalic acid relative to the total dicarboxylic acids was 1.6 mol %, was used, to obtain a polyester thick / thin multifilament. The properties of the obtained multifilament are shown in Table 5. The obtained polyester thick / thin multifilament had a mottled texture with little contrast between light and dark colors and a large degree of variation, and was lacking in characteristics as a design material. In addition, the target operability for advanced processing was not achieved.

[0070] [Comparative Examples 2 to 4] Spinning and drawing were carried out in the same manner as in Example 1, except that the blend ratio of copolymer polyester B / polyester A and the ratio of the SI component to the total dicarboxylic acids in the yarn were changed, to obtain thick / thin polyester multifilaments. The properties of the obtained multifilaments are shown in Table 5. The polyester thick / thin multifilaments obtained in Comparative Example 2 lacked color clarity.

[0071] The polyester thick-thin multifilament obtained in Comparative Example 3 had a small contrast between light and dark colors and a widely varying heathered pattern, which was uncharacteristic for a design material. In addition, the spinning, processing, and advanced processing operability did not achieve the targets.

[0072] The polyester thick-thin multifilament obtained in Comparative Example 4 had a low contrast between light and dark and a flecked appearance that lacked characteristics as a design material. In addition, the spinning, processing, and advanced processing operability did not achieve the targets.

[0073] [Comparative Examples 5 to 6] Spinning and drawing were carried out in the same manner as in Example 1, except that the number of spinneret holes and the polymer discharge rate used in Example 1 were changed, to obtain polyester thick / thin multifilaments. The properties of the obtained multifilaments are shown in Table 5. As shown in Table 5, the polyester thick / thin multifilaments obtained in Comparative Example 5 had a flecked appearance with little contrast between light and dark shades and lacked characteristics as a design material, and the targets for spinning, processing, and advanced processing operability were not achieved.

[0074] The polyester thick-thin multifilament obtained in Comparative Example 6 had a heathered appearance lacking characteristics as a design material, with a small contrast between light and dark, as shown in Table 5. In addition, the obtained fabric lacked a soft feel.

[0075] [Comparative Examples 7 to 8] Spinning and drawing were carried out in the same manner as in Example 1, except that the coefficient α in the draw ratio was changed, to obtain a polyester thick / thin multifilament. The properties of the obtained multifilament are shown in Table 5. As shown in Table 5, the obtained polyester thick / thin multifilament had a small contrast between light and dark shades and a flecked appearance that lacked characteristics as a design material.

[0076] Comparative Example 9 Spinning and drawing were carried out in the same manner as in Example 1, except that drawing was carried out using a hot roller instead of a friction resistor, to obtain a polyester thick / thin multifilament. The properties of the obtained multifilament are shown in Table 5. The obtained polyester thick / thin multifilament had a flecked pattern with little contrast between light and dark shades and large variations, and was a flecked pattern lacking characteristics as a design material.

[0077] [Comparative Example 10] Spinning and drawing were carried out in the same manner as in Example 1, except that only Polyester A was used, to obtain a polyester thick / thin multifilament. The properties of the obtained multifilament are shown in Table 5. The obtained polyester thick / thin multifilament lacked color development.

[0078] [Table 5] [Explanation of symbols]

[0079] 1: Highly oriented undrawn yarn 2: Feed roller 3: Friction resistor (heat pin) 4: Stretching roller 5: Feed roller 6: Winder A:NDR elongation B: Elongation to break C: Worcester waveform chart baseline D: A straight line indicating a fineness variation rate of +40% from the baseline of the Worcester waveform chart E: A straight line indicating a fineness fluctuation rate of +20% from the baseline of the Worcester waveform chart

Claims

1. A polyester thick / thin multifilament characterized by containing 0.6 to 2.5 mol % of an isophthalic acid component having a metal sulfonate group relative to the total dicarboxylic acid of the polyester, and satisfying the following A to B: A. Single yarn fineness: 0.40 to 1.2 dtex B. The average number of fineness fluctuation peaks (N40) in the Worcester waveform resulting from unevenness in the fineness in the longitudinal direction of the multifilament, with a fineness fluctuation rate width of 40% or more from the baseline, is 3 to 17 / m

2. The polyester thick / thin multifilament according to claim 1, characterized in that it has a breaking strength of 1.8 to 2.5 cN / dtex and a toughness of 19.0 or more.

3. 2. The polyester thick-thin multifilament according to claim 1, characterized in that the Worcester thick-thin unevenness resulting from unevenness in the lengthwise direction of the multifilament is 5 to 16%.

4. The polyester thick / thin multifilament according to claim 1, characterized in that the coefficient of variation CV% of the number of fineness fluctuation peaks (N20) having a fineness fluctuation rate width of 20% or more from the fineness fluctuation baseline of the Worcester waveform resulting from fineness unevenness in the longitudinal direction of the multifilament is 12% or less.

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