Antistatic spun yarn

Abstract

The present invention provides an antistatic spun yarn that is excellent in removing static electricity, is easy to handle in processes such as spinning, weaving, dyeing, and sewing, and has excellent whiteness. [Solution] An antistatic spun yarn containing conductive short fibers made of a thermoplastic resin containing a conductive substance, wherein when the total mass of the fibers constituting the antistatic spun yarn is 100% by mass, the conductive short fibers constitute 5 to 30% by mass. The fiber length of the conductive short fiber is 25 to 55 mm. L indicates the color tone of the antistatic spun yarn. * The value is 70 or higher, Antistatic spun yarn with a frictional withstand voltage of 2500 or less in both the warp and weft directions.

Description

Technical Field

[0001] The present invention relates to an antistatic spun yarn containing a specific amount of conductive staple fibers having a fiber length of 25 to 55 mm, excellent in antistatic performance, and excellent in whiteness.

Background Art

[0002] Among uniform clothing, especially in the case of work clothes worn in factories, antiexplosion properties are required from the viewpoint of safety, and antistatic properties are required from the viewpoint of suppressing disasters caused by static electricity adhering to the clothes.

[0003] Recently, considering the influence on medical electronic devices, antistatic properties are also required for, for example, white coats worn by doctors and nurses. This is because if the static electricity adhering to the white coat affects medical electronic devices, it may have a significant impact on the health and life of patients receiving treatment using the medical electronic devices.

[0004] To impart antistatic properties, generally, a filament fiber having conductivity (conductive filament fiber) may be woven into a fabric. However, since the conductive filament fiber has low strength, if it is used alone, yarn breakage frequently occurs during weaving, which is not preferable in terms of weaving performance. Therefore, by using other fibers in combination and processing them into a conductive composite yarn, yarn breakage during weaving is prevented and weaving performance is improved. As such a conductive composite yarn, for example, a yarn in which other fibers are wound around a conductive filament fiber is known (for example, Patent Document 1).

[0005] The conductive composite yarn described in Patent Document 1 was able to improve the weaving performance to some extent. However, there was a problem that yarn breakage of the conductive filament fiber easily occurred in the process of creating the conductive composite yarn, and the conductive performance at the location where the conductive filament was broken decreased. In addition, problems caused by yarn breakage of the conductive filament fiber, such as poor appearance quality of the greige fabric after passing through the weaving process, dyeing process, sewing process, etc., have not been sufficiently improved. Furthermore, in uniform clothing such as lab coats where whiteness is required, conductive fibers with sufficient whiteness and antistatic properties had not been proposed. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 3-269131 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The present invention aims to solve the above-mentioned problems and to provide an antistatic spun yarn that can be suitably used for uniform applications requiring whiteness, such as lab coats, and that also has excellent antistatic properties for removing static electricity, as well as excellent handling properties in processes such as spinning, weaving, dyeing, and sewing. [Means for solving the problem]

[0008] As a result of investigations aimed at solving the above-mentioned problems, the inventors of the present invention discovered that, while conductive filament fibers were conventionally used as conductive yarn to achieve antistatic properties in fabrics, by creating a spun yarn containing a specific amount of conductive short fibers of a specific fiber length, it is possible to improve the antistatic performance without causing deterioration in process passability due to breakage of conductive filament fibers, and thus arrived at the present invention.

[0009] In other words, the present invention is summarized in the following (1) to (4). (1) An antistatic spun yarn comprising conductive short fibers made of a thermoplastic resin containing a conductive substance, wherein when the total mass of the fibers constituting the antistatic spun yarn is 100% by mass, the conductive short fibers constitute 5 to 30% by mass, and the fiber length of the conductive short fibers is 25 to 55 mm. The antistatic spun yarn is colored L. *An antistatic spun yarn with a value of 70 or higher and a frictional withstand voltage of 2500 or less in both the warp and weft directions. Note L * The values ​​are determined by using a tubular knit fabric made solely from antistatic spun yarn, scouring the resulting fabric, measuring the reflectance using a Macbeth MS-CE3100 spectrophotometer, and calculating the density index from the CIE Lab's color difference formula. The frictional dielectric strength is measured using a tubular knit fabric made solely from antistatic spun yarn, and the resulting tubular knit fabric is scouring-treated. The measurement is performed using Method B of JIS L 1094: Test methods for the electrostatic properties of woven and knitted fabrics, with wool used as the abrasive cloth. (2) The antistatic spun yarn according to (1), wherein the fibers other than conductive staple fibers that constitute the antistatic spun yarn include polyester staple fibers and cellulose staple fibers, with polyester staple fibers being present in an amount of 5 to 65% by mass and cellulose staple fibers in an amount of 30 to 85% by mass. (3) The conductive short fiber is a composite fiber composed of a non-conductive component made of a thermoplastic resin and a conductive component made of a thermoplastic resin containing conductive particles, wherein titanium oxide fine particles coated on the surface with stannous oxide are used as the conductive particles, as described in (1). (4) Woven or knitted fabric containing the antistatic spun yarn described in (1). [Effects of the Invention]

[0010] The antistatic spun yarn of the present invention is less prone to breakage during processes such as spinning, weaving, dyeing, and sewing, is easy to handle, has excellent antistatic properties with superior static electricity removal capabilities, and also exhibits excellent whiteness. Therefore, woven or knitted fabrics obtained using the antistatic spun yarn of the present invention can be suitably used in uniform applications where explosion-proof properties are required, and even more so in lab coat applications. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view showing an example of a roving machine for obtaining the antistatic spun yarn (core-sheath type spun yarn) of the present invention. [Figure 2]It is a schematic cross-sectional view showing an example of a roving frame for obtaining the antistatic spinning yarn (core-sheath type spinning yarn) of the present invention.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described in detail. The antistatic spinning yarn of the present invention contains conductive short fibers made of a thermoplastic resin containing a conductive substance.

[0013] First, the conductive short fibers made of a thermoplastic resin containing a conductive substance will be described. The conductive short fibers constituting the antistatic spinning yarn in the present invention are preferably composite fibers composed of a non-conductive component made of a thermoplastic resin and a conductive component made of a thermoplastic resin containing conductive particles, and in a cross-section obtained by cutting the conductive short fibers perpendicular to the longitudinal direction of the fiber, it is preferable that a conductive component portion exists in the non-conductive component.

[0014] As the thermoplastic resins serving as the conductive component and the non-conductive component of the conductive short fibers, resins capable of melt spinning such as polyamide, polyester, and polyolefin can be used, but among them, polyester is preferable, and the non-conductive component is a polyester resin in which the repeating unit of ethylene terephthalate is 50 mol% or more, and further preferably 80 mol% or more, based on all the repeating units constituting the polyester resin.

[0015] Examples of copolymerization components other than ethylene terephthalate include isophthalic acid and adipic acid and the like. On the other hand, the conductive component is preferably a resin composition containing 50 to 80% by mass of conductive particles in polybutylene terephthalate.

[0016] As the conductive particles used in the present invention, in order to obtain an antistatic spinning yarn with excellent whiteness, it is preferable to use titanium oxide fine particles whose surface is coated with stannic oxide, and those obtained by mixing and firing antimony oxide with the titanium oxide fine particles to form conductive particles can also be used.

[0017] The antistatic spun yarn uses conductive short fibers for a part of the short fibers constituting the antistatic spun yarn. The fiber length of the conductive short fibers is 20 to 55 mm, preferably 25 to 52 mm, and more preferably 25 to 45 mm. When the fiber length is less than 20 mm, deterioration of weaving and knitting properties due to a decrease in the single yarn strength of the antistatic spun yarn, and deterioration of fabric quality such as pilling property due to an increase in the number of hairy fibers occur.

[0018] On the other hand, when the fiber length exceeds 55 mm, the antistatic effect due to a decrease in the number of conductive short fiber ends per unit length of the antistatic spun yarn decreases (increase in friction withstand voltage). In addition, yarn streaks are likely to increase due to the fiber length difference from other fibers such as cellulose short fibers, and the single yarn strength partially decreases due to twist streaks, resulting in deterioration of fabric quality.

[0019] The antistatic spun yarn of the present invention is characterized in that, as the conductive fiber, a short fiber form is used instead of a filament form. However, when using a conductive fiber in a short fiber form, the friction withstand voltage becomes lower and the antistatic property becomes excellent. This is presumably because the corona discharge of the conductive substance occurs at the ends of the electrodes, that is, both ends of the conductive fiber. Therefore, the amount of both ends is larger when the conductive fiber is in a short fiber form than when it is in a filament form, so corona discharge is more likely to occur. Therefore, it is considered that a spun yarn containing a conductive fiber in a short fiber form with many ends serving as electrodes has a low friction withstand voltage and excellent antistatic properties.

[0020] The antistatic spun yarn of the present invention preferably contains polyester short fibers and cellulose short fibers as fibers other than the conductive short fibers constituting the antistatic spun yarn. First, let's explain polyester staple fibers. The polyester resin that makes up the polyester staple fibers is preferably a polyester resin in which the repeating units of ethylene terephthalate account for 50 mol% or more, more preferably 80 mol% or more, and more preferably 95 mol% or more, relative to the total repeating units that make up the polyester resin. Other copolymer components besides ethylene terephthalate include isophthalic acid and adipic acid.

[0021] The fiber length of the polyester staple fibers is 20 to 55 mm, preferably 25 to 52 mm, and more preferably 25 to 45 mm. If the fiber length is less than 20 mm, the weaving and knitting properties of the antistatic spun yarn will deteriorate due to a decrease in single-yarn strength, and the fabric quality will deteriorate due to factors such as pilling caused by an increase in the number of fibers. On the other hand, when the fiber length exceeds 55 mm, the difference in fiber length with other fibers such as cellulose short fibers tends to increase yarn unevenness, which can lead to a partial decrease in single-yarn strength and a deterioration in fabric quality due to uneven twisting.

[0022] In this invention, cellulose short fibers include plant fibers such as cotton and hemp, regenerated cellulose fibers such as viscose rayon and Tencel (modal, lyocell), and acetate fibers. Among these, cotton is preferred, and the fiber length is preferably 55 mm or less.

[0023] When the total mass of fibers constituting the antistatic spun yarn is taken as 100% by mass, the content of conductive short fibers is 5 to 30% by mass, and more preferably 10 to 25% by mass. Furthermore, the polyester staple fiber content is preferably 5 to 65% by mass, and the cellulose staple fiber content is preferably 30 to 85% by mass. If the conductive staple fiber content in antistatic spun yarn is less than 5% by mass, the static electricity removal performance will be poor. On the other hand, if the conductive staple fiber content exceeds 30% by mass, yarn breakage is more likely to occur in processes such as yarn spinning, weaving, dyeing, and sewing.

[0024] The indicator of the superior whiteness of the antistatic spun yarn of the present invention is L, which indicates the color tone. * The value must be 70 or higher, especially L * The value is preferably 75 or higher, and more preferably 80 or higher. Furthermore, in the present invention, L * The value is obtained by using only antistatic spun yarn, knitting it in a tubular knit, and then scouring it under the following conditions: 80°C for 20 minutes, with Sunmol FL 1 g / l and a bath ratio of 1:50. The reflectance is measured using a Macbeth MS-CE3100 spectrophotometer, and the density index is determined from the CIE Lab color difference formula. The average of four measurements is taken as the L* value.

[0025] An indicator of the excellent static electricity removal performance of the antistatic spun yarn of the present invention is that the frictional withstand voltage is 2500 or less in both the warp and weft directions, preferably 2000 or less in both directions, and even more preferably 1500 or less in both directions. In this invention, the frictional voltage is measured using a tubular knitted fabric made solely from antistatic spun yarn, scouring conditions: 80°C for 20 minutes, with Sanmol FL 1 g / l and a bath ratio of 1:50, and using Method B of JIS L 1094: Test methods for the electrostatic properties of woven and knitted fabrics, with wool used as the abrasive cloth.

[0026] Examples of the antistatic spun yarn of the present invention include a blended yarn obtained from a sliver containing conductive staple fibers, polyester staple fibers, and cellulose staple fibers; a core-sheath type (two-layer structure) spun yarn in which a sliver containing conductive staple fibers and polyester staple fibers is arranged as the core and cellulose staple fibers as the sheath; a core-sheath type (two-layer structure) spun yarn in which a sliver containing polyester staple fibers is arranged as the core and conductive staple fibers and cellulose staple fibers as the sheath; and a finely spun blended yarn in which one part is a roving containing conductive staple fibers, polyester staple fibers, and cellulose staple fibers, and the other part is a roving containing polyester staple fibers and cellulose staple fibers.

[0027] In the present invention, the antistatic spun yarn preferably uses titanium oxide fine particles coated with stannous oxide on the surface of conductive particles in the conductive short fibers. However, in order to obtain a spun yarn with excellent whiteness, it is more preferable to use a core-sheath type (two-layer structure) spun yarn in which conductive short fibers are arranged in the core.

[0028] The present invention describes a method for producing antistatic spun yarn. The antistatic spun yarn of the present invention can be obtained by preparing conductive short fibers by cutting conductive filaments having a predetermined electrical resistance value to a predetermined fiber length, and then subjecting these conductive short fibers to a known spinning process.

[0029] Conductive filaments can be obtained by melt spinning using conventional methods. Specifically, a polyester resin containing 1 to 15 mol% isophthalic acid (IPA) as a copolymer component, with ethylene terephthalate as the main repeating unit and an acid component of 100 mol%, is used for the sheath, and a PBT resin containing 50 to 80% by mass of titanium dioxide fine particles coated with stannous oxide is used for the core. Using a conventional composite spinning apparatus, the materials are kneaded and melted in an extruder, for example, and then extruded through a core-sheath type spinneret to perform melt spinning and obtain an undrawn yarn. The wound undrawn yarn is then heated at 50 to 150°C and drawn to 1.2 to 2.0 times its original length, followed by heat treatment at 130 to 170°C, and then wound to obtain a conductive filament.

[0030] Multiple conductive filaments are bundled together to create a tow made of conductive filaments. This tow made of conductive filaments is crimped using a crimper or gear crimping, and then a spinning oil is applied and dried. After cutting this crimped and oil-treated tow made of conductive filaments to a predetermined length with a cutter, the fibers are opened to obtain conductive short fibers for spinning.

[0031] The obtained conductive short fibers are mixed with other fibers and fed into a cotton-beating machine to obtain a sheet-like wrap. The obtained wrap is fed into a carding machine, and after going through a combing process, the web is spun, bundled, and pressed with a calender roll to obtain a card sliver containing conductive short fibers.

[0032] Next, in the drawing process, a sliver M containing a predetermined amount of conductive short fibers is obtained by repeatedly stretching multiple slivers, either consisting only of card slivers containing conductive short fibers or slivers consisting of other fibers besides conductive short fibers.

[0033] Next, in the roving process, the sliver M containing these conductive short fibers is supplied, stretched on each roller tube, and then wound while being twisted to obtain roving yarn containing conductive short fibers. The roving containing these conductive short fibers is further stretched and twisted in a predetermined direction during the spinning process to obtain the antistatic spun yarn containing the conductive short fibers of the present invention. The antistatic spun yarn obtained after the spinning process is wound up to a predetermined weight and length in the next finishing process.

[0034] At this stage, the yarn is typically wound up while passing it between defect-sensing sensors to check for residual defects (slubs, neps, fine threads, stray threads, etc.) contained in the spun yarn during the finishing process. By detecting residual defects within a specific range set by the defect detection sensor and winding the yarn while joining together yarns that do not contain defects, it is possible to obtain spun yarn from which residual defects within the specified range have been removed.

[0035] The woven or knitted fabric of the present invention is a woven or knitted fabric that contains at least a portion of the antistatic spun yarn of the present invention described above. The content of the antistatic spun yarn in the woven or knitted fabric of the present invention is preferably 0.03% by mass or more, and more preferably 0.15% by mass or more. The upper limit of the content of the antistatic spun yarn varies depending on the intended use of the woven or knitted fabric, but for example, for clothing applications, it is generally preferably 30% by mass or less.

[0036] The woven or knitted fabrics of the present invention can be used, for example, in clothing applications (work clothes, dustproof clothing, cleanroom clothing, etc.) or in industrial material applications (smartphone gloves, smart textiles, anti-static brushes used in electronic devices, etc.).

[0037] The woven or knitted fabric of the present invention is not particularly limited in terms of structure, but it is preferable from the viewpoint of antistatic performance to have a structure in which the antistatic spun yarn is exposed on the surface of the fabric, or to use antistatic spun yarn for both the warp and weft threads.

[0038] In the case of woven fabrics, examples include plain weave, twill weave, satin weave, dobby weave, and double weave. It is preferable to use the antistatic spun yarn of the present invention in either the warp threads or the weft threads, or both, and to arrange the antistatic spun yarn in the fabric at intervals of 10 mm or less, preferably at intervals of 8 to 1 mm. In the case of knitted fabrics, circular knitting, weft knitting, or warp knitting may be used. In the case of circular knitting or weft knitting, it is preferable to insert the antistatic spun yarn of the present invention at intervals of 10 mm or less, and it is preferable to use it so that it is arranged at intervals of 8 to 1 mm. [Examples]

[0039] Next, the present invention will be specifically described with reference to examples. The various characteristic values ​​and evaluations in the examples are as follows.

[0040] [L * Value (whiteness) The measurements were taken using the method described above. A tubular knitting machine with a 40-inch diameter and 20 gauge was used, and the knitting tension, stitch size, etc., were adjusted as appropriate, and the fabric was knitted in plain knit. [Friction resistance (antistatic properties)] The measurements were taken using the method described above. A tubular knitting machine with a 40-inch diameter and 20 gauge was used, and the knitting tension, stitch size, etc., were adjusted as appropriate, and the fabric was knitted in plain knit.

[0041] The cellulose staple fibers (cotton fibers) and polyester staple fibers used in the examples were as follows: [Cotton fiber] Australian cotton, ANDY medium-staple cotton grade (effective fiber length 1 1 / 8 inches (29.4 mm)) [Polyester staple fiber] Made by Indorama Polyester Industries PCL., 100% Polyester Staple Fiber, 1.2D x 38mm, Semi-Dull Raw White, Fiber Length: 38mm, Fineness: 1.2 denier

[0042] Example 1 (conductive filament) A slurry of terephthalic acid (TPA) and ethylene glycol (EG) was supplied to the polyester resin sheath esterification reactor and reacted under conditions of 250°C and 50 hPa, yielding a reaction product with an esterification reaction rate of 95%. A slurry consisting of isophthalic acid (IPA) and ethylene glycol was placed in another esterification reaction vessel, and the esterification reaction was carried out at a temperature of 200°C for 3 hours to obtain a reaction solution of isophthalic acid and ethylene glycol. The reaction product of TPA and EG, a reaction solution of isophthalic acid and ethylene glycol, an ethylene glycol dispersion of titanium dioxide, and a polymerization catalyst were added, and a melt polymerization reaction was carried out under reduced pressure in the reactor to obtain a copolymerized polyester resin (8 mol% IPA copolymerized as the acid component, with a titanium dioxide content of 2 wt%, and a melting point of 234°C). The core polyester resin was made by kneading 65% by mass of titanium dioxide fine particles coated with antimond-doped stannous oxide onto the surface of polybutylene terephthalate (PBT) to obtain a resin with a melting point of 223°C.

[0043] Polyester resin for the sheath and polyester resin for the core were prepared as described above. These resins were supplied to a composite spinning apparatus, and melt spinning was performed using a spinneret designed so that the cross-sectional shape of the fiber had a core and a sheath. At this time, the area ratio of the core to the sheath (core / sheath) was 21 / 79, and the sheath was arranged so that it covered the entire surface of the core, and the spinning was performed at a spinning temperature of 270°C. Cooling air (temperature 24°C) was blown onto the melt-spun yarn from the spinneret nozzle at a position 130 mm from the bottom surface of the spinneret nozzle to cool it, then it was bundled and oiled, and then wound up at a speed of 2700 m / min on a take-up roller to obtain a partially undrawn yarn. The obtained partially undrawn yarn was heat-treated between the first roller (temperature 110°C) and the second roller (room temperature) by placing a 150°C heater plate between the first and second rollers, and was drawn at a draw ratio of 1.3 times to wind up a conductive filament (60 dtex / 24 f).

[0044] (Conductive short fibers) By repeatedly bundling multiple conductive filaments using an RT winder, a tow with a total fineness of approximately 400,000 dtex was prepared. After crimping this tow, it was passed through an oil bath for applying spinning oil, and then dried in a hot air dryer to obtain a crimped and oil-treated tow. Finally, this crimped and oil-treated tow was wound and cut with a rotary cutter to obtain conductive short fibers of a standard length of 38 mm.

[0045] The measured values ​​of the raw cotton properties of the conductive short fibers obtained above were as follows. Apparent fineness: 2.61 dtex, average fiber length: 38.9 mm, tensile strength: 1.92 cN / dtex, elongation: 89.9%, crimp count: 10.1 crimps / 25 mm, crimp rate: 7.9%, oil extract content: 0.18%. Here, the measurement methods for each raw cotton property value were in accordance with JIS L 1015. Apparent fineness was measured using the correct fineness method A, average fiber length using method C, tensile strength and elongation were measured using a constant-speed elongation tester with a gripping interval of 20 mm and a tensile speed of 20 mm / min. Oil extract was measured using diethyl ether as the extracting oil.

[0046] (Antistatic spun yarn) The conductive short fibers obtained above were fed into a cotton blending machine, and after going through each cotton blending process, a sheet-like wrap made of conductive short fibers was obtained. The wrap made of these conductive short fibers was fed into a carding machine, and after going through a combing process in the carding machine, the web was spun and bundled, and pressed with a calender roll to obtain a carded sliver of 300 gr / 6 yd (hereinafter, gr: 1 gelen = 0.06479891 grams, yd: 1 yard = 0.9144 meters). Furthermore, using the same method, a 300g / 6yd card sliver made of cotton fibers and a 300g / 6yd card sliver made of polyester staple fibers were prepared.

[0047] Next, using the obtained card slivers consisting of conductive staple fibers, cotton fibers, and polyester staple fibers, the number of each sliver fed into the blending machine was adjusted, and the blending process was repeated twice to obtain a blended sliver containing conductive staple fibers: 15% by mass, polyester staple fibers: 30% by mass, and cotton fibers: 55% by mass. Using a roving machine, the resulting drawn sliver was fed in, stretched 7.4 times, and then twisted in the Z direction to obtain a roving containing conductive short fibers with a roving mass of 270g / 30yd and a twist count of 0.96 turns / 2.54cm. This roving was passed through the trumpet (guide) of a spinning machine, and after being stretched 37.2 times through the back roller, apron, and front roller in that order, it was twisted in the Z direction to a twist count of 22.2 turns / 2.54 cm, yielding a 34-count (English cotton count) antistatic spun yarn.

[0048] Example 2 Using the same conductive staple fibers, cotton fibers, and polyester staple fibers as in Example 1, the number of each sliver supplied to the blending machine was adjusted, and the blending process was repeated twice to obtain a blended sliver containing conductive staple fibers: 25% by mass, polyester staple fibers: 30% by mass, and cotton fibers: 45% by mass. Except for using this drawn sliver, the roving and spinning processes were the same as in Example 1 to obtain an antistatic spun yarn of the same English cotton count as in Example 1.

[0049] Example 3 Using the same conductive staple fibers, cotton fibers, and polyester staple fibers as in Example 1, the number of each sliver fed into the blending machine was adjusted, and the blending process was repeated twice to obtain a blended sliver containing conductive staple fibers: 8% by mass, polyester staple fibers: 30% by mass, and cotton fibers: 62% by mass. Except for using this drawn sliver, the roving and spinning processes were the same as in Example 1 to obtain an antistatic spun yarn of the same English cotton count as in Example 1.

[0050] Example 4 (Sliver S1: Sliver for the core) The same conductive staple fibers and polyester staple fibers as in Example 1 were weighed so that the mass ratio of conductive staple fibers to polyester staple fibers was 1 / 2 and fed into a cotton blending machine. After going through each step of the cotton blending machine, a sheet-like wrap (wrap R1) made of conductive staple fibers and polyester staple fibers was obtained. This wrap R1 was fed into a carding machine, where it underwent a combing process. After that, the web was spun, bundled, and pressed with a calender roll to obtain a 300g / 6yd card sliver. Next, using the obtained card sliver described above, the process of stretching the eight strands together to 9.8 times their original length was repeated twice in the blending process to obtain a 200g / 6yd blended sliver S1 (with a mass ratio of conductive short fibers to polyester short fibers of 1 / 2). (Sliver S2: Sliver for sheath) Only the same cotton fibers as in Example 1 were fed into the cotton blending machine to obtain a sheet-like wrap made of cotton fibers. The wrap made from these cotton fibers was fed into a carding machine, where it underwent a combing process. After that, the web was spun, bundled, and pressed with a calender roll to obtain a 300g / 6yd card sliver. Next, using the obtained cotton fiber card sliver, the process of stretching the eight strands together to 8.8 times their original length was repeated twice in the drawing process to obtain a 250g / 6yd drawn sliver S2 made of 100% cotton fiber. Through the above process, in order to create a core-sheath structured spun yarn, sliver S1 was prepared as the core sliver and sliver S2 as the sheath sliver.

[0051] Using a roving machine with the structure shown in Figures 1 and 2, core sliver S1 and sheath sliver S2 were supplied, and after being stretched 8.3 times through the back roller (A), intermediate roller (B), apron (C), and front roller (D) in that order, the mass ratio of each sliver was set to S1:S2 = 45:55, and the angle of advance of the core sliver S1 toward the flyer head (E) with respect to the draft direction in Figure 2 was set to 60°, and the sheath sliver S2 was wound around the core sliver S1 while twisting in the Z direction to achieve a twist coefficient of 0.9, and the winding was carried out while applying a false twist effect with the flyer (F), resulting in a roving (G) with a core-sheath structure, a roving mass of 270g / 30yd, and a twist count of 0.86 turns / 2.54cm. This roving (G) was passed through the trumpet (guide) of a spinning machine, and after being stretched 37.2 times through the back roller, apron, and front roller in that order, it was twisted in the Z direction to a twist count of 22.2 times / 2.54 cm, yielding a 34-count (English cotton count) two-layer antistatic spun yarn.

[0052] Comparative Example 1 (conductive filament) A slurry of terephthalic acid (TPA) and ethylene glycol (EG) was supplied to the polyester resin core esterification reactor and reacted under conditions of 250°C and 50 hPa, yielding a reaction product with an esterification reaction rate of 95%. A slurry consisting of isophthalic acid (IPA) and ethylene glycol was placed in another esterification reaction vessel, and the esterification reaction was carried out at a temperature of 200°C for 3 hours to obtain a reaction solution of isophthalic acid and ethylene glycol. The reaction product of TPA and EG, a reaction solution of isophthalic acid and ethylene glycol, and a polymerization catalyst are added, and the reactor is subjected to a reduced pressure to carry out a melt polymerization reaction, resulting in a copolymerized polyester resin (8 mol% IPA copolymerized as the acid component, with a melting point of 234°C and a melt viscosity of 1340 dPa·s). -1) was obtained. Sheath polyester resin: Polybutylene terephthalate (PBT) mixed with 25% by mass of conductive carbon black, melting point 223°C, melt viscosity 1450 dPa·s -1 The resin was obtained.

[0053] Polyester resin for the core and polyester resin for the sheath were prepared as described above. These resins were supplied to a composite spinning apparatus, and melt spinning was performed using a spinneret designed so that the cross-sectional shape of the fiber had a core and a sheath. At this time, the area ratio of the core to the sheath (core / sheath) was 85 / 15, and the sheath was arranged so that it covered the entire surface of the core, and the spinning was performed at a spinning temperature of 270°C. Cooling air (temperature 24°C) was blown onto the melt-spun yarn from the spinneret nozzle at a position 120 mm from the bottom surface of the spinneret nozzle to cool it, then it was bundled and oiled, and then wound up at a speed of 2700 m / min on a take-up roller to obtain a partially undrawn yarn. The obtained partially undrawn yarn was heat-treated between the first roller (temperature 90°C) and the second roller (room temperature) by placing a 140°C heater plate between the first and second rollers, and was drawn at a draw ratio of 1.7 times to wind up a conductive filament (28 dtex / 6 f).

[0054] (Conductive short fibers) A tow with a total fineness of 11200 dtex was prepared by repeatedly bundling multiple conductive filaments using an RT winder. After crimping this tow, it was passed through an oil bath for applying spinning oil, and then dried in a hot air dryer to obtain a crimped and oil-treated tow. Finally, this crimped and oil-treated tow was wound and cut with a rotary cutter to obtain conductive short fibers of a standard length of 38 mm. Except for using the above-mentioned conductive short fibers, the process was carried out in the same manner as in Example 1, going through the roving and spinning steps to obtain an antistatic spun yarn of the same English cotton count as in Example 1.

[0055] Comparative Example 2 Using only card slivers made of cotton fibers and card slivers made of polyester staple fibers, the same as in Example 1, the number of each sliver fed into the blending machine was adjusted, and the blending process was repeated twice to obtain a blended sliver containing 30% polyester staple fibers and 70% cotton fibers by mass. Except for using this drawn sliver, the roving and spinning processes were the same as in Example 1 to obtain a spun yarn with the same English cotton count as in Example 1, but without conductive short fibers.

[0056] Table 1 shows the raw cotton composition of the spun yarns obtained in Examples 1-4 and Comparative Examples 1-2, as well as the measurement results of the frictional voltage withstand voltage.

[0057] [Table 1]

[0058] As is clear from Table 1, the antistatic spun yarns obtained in Examples 1 to 4 contained a predetermined mass% of highly white conductive short fibers, and their frictional voltage resistance and whiteness were within the range defined in the present invention, thus exhibiting excellent antistatic properties and whiteness. In particular, the spun yarn of Example 4 was made into a core-sheath structure, taking into consideration the occurrence of color unevenness due to conductive short fibers and whiteness, and as a result, it had no occurrence of yarn unevenness in the longitudinal direction of the spun yarn and had superior color tone compared to the spun yarns of Examples 1, 2, and 3.

Claims

1. An antistatic spun yarn containing conductive short fibers made of a thermoplastic resin containing a conductive substance, wherein when the total mass of the fibers constituting the antistatic spun yarn is 100% by mass, the conductive short fibers constitute 5 to 30% by mass, and the fiber length of the conductive short fibers is 25 to 55 mm. The antistatic spun yarn is colored L. ＊ The value is 70 or higher, An antistatic spun yarn with a frictional withstand voltage of 2500 or less in both the warp and weft directions. Note L ＊ The values ​​are determined by using a tubular knit fabric made solely from antistatic spun yarn, scouring the resulting fabric, measuring the reflectance using a Macbeth MS-CE3100 spectrophotometer, and calculating the density index from the CIE Lab color difference formula. The frictional withstand voltage is measured using a tubular knit fabric made solely from antistatic spun yarn, which has been scouring, and using Method B of JIS L 1094: Test methods for the electrostatic properties of woven and knitted fabrics, with wool used as the abrasive cloth.

2. The antistatic spun yarn according to claim 1, wherein the fibers other than conductive staple fibers constituting the antistatic spun yarn include polyester staple fibers and cellulose staple fibers, with polyester staple fibers present in an amount of 5 to 65% by mass and cellulose staple fibers in an amount of 30 to 85% by mass.

3. The conductive short fiber is a composite fiber composed of a non-conductive component made of a thermoplastic resin and a conductive component made of a thermoplastic resin containing conductive particles, wherein titanium oxide fine particles coated on the surface with stannous oxide are used as the conductive particles, according to claim 1.

4. A woven or knitted fabric containing the antistatic spun yarn described in claim 1.

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