Knit fabric

Abstract

The present invention provides comfortable innerwear that offers a pleasant touch, provides a cool sensation upon contact with the skin (contact cooling sensation), and does not stick to the skin during perspiration (skin-separating property) in high-temperature and high-humidity environments.　This can be achieved by a knit fabric composed of polyamide fibers and polyurethane elastic fibers, in which the cross-sectional shape of the single filaments of the polyamide fibers is a flat multilobal shape, and the single filament fineness of the polyamide fibers is 0.8 dtex or less.

Description

knit

[0001] The present invention relates to knitwear.

[0002] Synthetic fibers such as polyamide and polyester fibers have excellent mechanical and chemical properties and are therefore widely used in clothing and industrial applications.

[0003] In recent years, with growing environmental awareness, including the SDGs and measures to combat global warming, attention has been focused on functional clothing materials that are comfortable to wear and have a cooling sensation without sticking to the skin (feeling sticky), particularly as a way to combat the heat in hot and humid summer environments, and various inventions have been made to address this.

[0004] For example, Patent Document 1 reports cool-to-the-touch stockings and innerwear that use flat cross-section polyamide fibers to which 0.5 to 8% by weight of an inorganic compound has been added, and in which the value K, which indicates the cool-to-the-touch sensation, is specified by dividing qmax by the basis weight.

[0005] Furthermore, Patent Document 2 reports a knitwear that combines a cooling sensation with anti-transparency by using a blend of polyester fiber containing 1.0 to 5.0% by weight of titanium oxide and having one or more convex portions in a flat cross section, and cellulose fiber.

[0006] Furthermore, Patent Document 3 reports a woven or knitted fabric using flat multilobal cross section polyamide fibers containing 0 to 6% by weight of a moisture absorbent.

[0007] JP 2004-107809 A JP 2012-211405 A JP 2016-65328 A

[0008] However, in the known technology of Patent Document 1, the maximum qmax indicating coolness to the touch is 0.29 W / cm ２ Furthermore, although it is possible to impart a powdery feel by adding inorganic compounds, the physical unevenness of the fiber surface due to the presence of fine particles does not significantly change the frictional force with the skin, and it is not possible to prevent the fabric from sticking to the skin when sweating.

[0009] In the known technology of Patent Document 2, polyester fiber of 56 dtex is mixed with cellulose fiber of the same fineness, so the resulting knitted fabric is thick and has a stiff texture that is uncomfortable for use in contact with the skin. In addition, the maximum qmax in an environment of 20°C and 65% RH is 0.28 W / cm ２ However, a satisfactory cooling sensation is not obtained.

[0010] The prior art of Patent Document 3 discloses a woven or knitted fabric using polyamide fibers with a flattened multilobal cross section, but does not disclose a specific knit fabric structure. Polyamide fibers with irregular cross sections have a larger fiber surface area than circular cross sections, making orientation and crystallization less likely to proceed. This results in a loose fiber structure, which leads to quality defects such as vertical and horizontal stripes when dyeing the fabric, making it difficult to put into practical use. In addition, the cool-to-the-touch feel is also insufficient.

[0011] As described above, conventional techniques have not been able to achieve both a satisfactory cooling sensation and a comfortable fit in knitwear that has a cooling sensation.

[0012] To provide a knitted fabric that is free from fabric defects, has excellent practical quality, feels good to the touch, gives a cool feeling when it touches the skin (cool to the touch), does not stick to the skin when sweating (releasing property), and can provide comfortable clothing such as innerwear.

[0013] The present invention solves the above problems by providing the following configurations. (1) A knit made of polyamide fiber and polyurethane elastic fiber, in which the cross-sectional shape of a single polyamide fiber yarn is a flattened multilobal shape and the single polyamide fiber yarn fineness is 0.8 dtex or less. (2) The knit according to (1) above, in which the total fineness of the polyamide fiber is 66 dtex or less. (3) The knit according to (1) or (2) above, in which the total fineness of the polyurethane elastic fiber is 0.5 to 1.0 times the total fineness of the polyamide fiber. (4) The knit fabric has a basis weight of 100 g / m ２ ~200g / m ２ The qmax according to the JIS L1927 (2020) cooling sensation evaluation is 0.320 W / cm ２ The knit described in any one of (1) to (3) above.

[0014] The knitwear of the present invention is soft to the touch in a hot and humid environment, feels cool to the touch (cool to the touch), and does not stick to the skin when sweating (moisture-wicking), making it possible to produce comfortable knitwear clothing.

[0015] Fig. 1 is a schematic diagram of the cross-sectional shape of a single filament of a flat multilobal polyamide fiber of the present invention. Fig. 2 is a schematic diagram showing the shape of the outlet holes of the spinneret used in the examples of the present invention.

[0016] The knit of the present invention is composed of polyamide fibers and polyurethane elastic fibers.

[0017] The mechanism behind the desired cooling sensation is that when the fabric touches the skin, heat is transferred to the lower temperature side of the fabric, creating a cooling sensation. Materials with high thermal conductivity, thermal diffusivity, and moisture absorption heat (hygroscopicity) exhibit a high cooling sensation.

[0018] For example, the thermal conductivity of materials used in clothing that comes into contact with the skin is rayon (0.58), cotton (0.54), polyamide (0.38), polyurethane (0.30), and polyester (0.18). The numbers in parentheses are thermal conductivity (unit: W / m·K). The moisture absorption is rayon (11.0), cotton (11.0), polyamide (4.5), polyurethane (1.0), and polyester (0.4). The numbers in parentheses are the official moisture regain (unit: %).

[0019] In addition, the desired element of moisture-wicking is achieved by using a highly hydrophobic material, but hydrophobicity and moisture absorption are in a trade-off relationship. Rayon and cotton have poor moisture-wicking properties because they absorb sweat and are slow to dry. On the other hand, polyester, polyurethane, and polyamide have excellent quick-drying properties, making them excellent moisture-wicking materials when sweating. Therefore, the combination of polyamide and polyurethane is the best material to achieve both a cool touch and moisture-wicking properties.

[0020] In addition, polyurethane has a volumetric specific heat, which is the product of specific heat and density, of 2045 kJ / m ３- It is a material with a high K, and this high volumetric specific heat means that the material's temperature does not change easily. In other words, it is slow to follow the temperature, and a temperature difference occurs between the material and body temperature, which creates a cooling effect. Therefore, in this invention, polyurethane elastic fiber is actively used as a material that can further improve the cooling sensation to the touch.

[0021] In addition, to give the knit fabric stretchability, it is optimal to use polyurethane elastic fibers in combination with polyamide fibers.

[0022] In the present invention, further intensive research was conducted on knitwear made of polyamide fibers and polyurethane elastic fibers, and by modifying the polyamide fibers (cross-sectional shape, ultra-thinning of single yarns), it was possible to achieve a high level of coolness to the touch and comfortable wearability that was previously unattainable.

[0023] The polyamide fiber used in the present invention is a fiber made of a polymer in which hydrocarbon groups are linked to the main chain by amide bonds. Specific examples of the polymer include polycaprolactam (nylon 6), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 6,10), polytetramethylene adipamide (nylon 4,6), and pentane-1,5-diamine (nylon 5,6).

[0024] Polyamide has a hydrophilic amide group in the main chain of the molecule, making it a material with relatively excellent moisture absorption among synthetic fibers. From the viewpoint of moisture absorption, which is one factor in realizing a cool-to-the-touch feel, nylon 6, nylon 66, and nylon 5,6 are particularly suitable.

[0025] The polyamide may contain a matting agent or a moisture absorbent as appropriate. Examples of matting agents include inorganic compounds, such as titanium oxide, barium sulfate, aluminum oxide, zirconium oxide, calcium oxide, and magnesium oxide. Titanium oxide and barium sulfate are preferred from the standpoints of productivity and coolness to the touch when producing polyamide fibers. The inclusion of these inorganic compounds can impart a matte, powdery feel to the knitted fabric. However, since the inclusion of inorganic compounds inhibits secondary crystallization of the polymer, increasing the content decreases the strength of the raw yarn, so the preferred content is 0.5% to 2.0% by mass.

[0026] Examples of the moisture absorbent include polyvinylpyrrolidone (PVP), polyether amide, polyalkylene glycol, polyether ester amide, etc., with PVP being particularly desirable, and the content thereof is preferably 0 to 5% by mass.

[0027] Furthermore, with environmental issues receiving increasing attention, the use of plant-derived biopolymers or recycled polymers in the present invention is also preferable from the viewpoint of reducing the environmental load. It is preferable that the polyamide used in the present invention is a recycled polymer, and recycled polymers recycled by any of chemical recycling, material recycling, and thermal recycling methods can be used.

[0028] The polyurethane elastic fiber contains a polyurethane polymer. The polyurethane polymer is obtained by employing a known urethane reaction technique in which a prepolymer obtained by reacting a polymeric diol with a diisocyanate is subjected to a chain extension reaction with a polyfunctional active hydrogen-containing compound as a chain extender. The polymeric diol is preferably a polyether diol, a polyester diol, or a polycarbonate diol. The molecular weight of the polymeric diol is preferably a number-average molecular weight of 1,000 to 8,000. The diisocyanate has two isocyanate groups in the molecule, and examples of the diisocyanate include aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates.

[0029] The cross-sectional shape of the polyamide fiber single yarn constituting the knit of the present invention is a flattened multi-lobed shape with multiple concave and convex portions, as illustrated in Figure 1. The flattened multi-lobed shape increases the contact area of ​​the polyamide fiber, which has high thermal conductivity, with the skin when knitted, resulting in an improved cool-to-the-touch feel. Furthermore, the numerous concave portions provide an extremely smooth feel, and the capillary action generated by the minute voids improves water absorption. This results in excellent skin-releasing properties and a smooth feel even when sweating, providing a comfortable fit even in hot and humid summer environments.

[0030] Even in the case of a flat shape without any unevenness, a cooling sensation can be achieved by increasing the contact area, but the fabric tends to stick to the skin when sweating.

[0031] The number of lobes in the flattened multi-lobed shape is preferably 4 or more, more preferably 6 to 8. The number of lobes referred to here means the number of convex portions on the cross section of the fiber.

[0032] The flattening degree of the flattened multi-lobed shape (A / B in FIG. 1 ) is preferably 1.50 to 2.50. The flattening degree here refers to the value obtained by dividing the length of the long side of the circumscribing rectangle (rectangle) of the cross-sectional shape by the length of the short side. Here, the circumscribing rectangle (rectangle) is the smallest rectangle that encloses the flattened multi-lobed shape. By setting the flattening degree to 1.50 or more, the contact area with the skin surface can be increased, resulting in improved heat flux per unit area and thereby improved coolness to the touch. A higher flattening degree results in a softer feel compared to a perfectly circular shape (flattening degree of 1.0), but tends to reduce the strength of the raw yarn. A flattening degree of 2.50 or less is preferred because it ensures the strength of the fiber and improves the burst strength of the knit fabric. A more preferred flattening degree is 1.50 to 2.30, and even more preferably 1.60 to 2.00.

[0033] The irregularity of the flattened multi-lobed shape will now be explained. The convex points and concave points of the flattened multi-lobed shape are determined. If the number of leaves is even, line segments are drawn between the convex points on the long side of the circumscribing quadrangle (rectangle) and the convex points symmetrical to it. Similarly, line segments are drawn between the concave points symmetrical to it. Specifically, line segments are drawn connecting the convex points facing each other across the center line connecting the centers of the short sides of the circumscribing quadrangle (rectangle). In other words, line segments are drawn connecting the concave points and the convex points so that they are nearly parallel to each other, with the short side of the circumscribing quadrangle (rectangle) as the axis. Taking the example of the flattened eight-lobed cross-sectional shape of Figure 1, concave points (Q1 to Q4) and convex points (P1 to P8) are determined, and line segments are drawn connecting convex points P1 and P4, concave points Q1 and Q3, convex points P2 and P5, concave points Q2 and Q4, and convex points P3 and P6, respectively, from left to right. In this example of the flattened eight-lobed cross-sectional shape of Figure 1, the lengths of the line segments drawn between symmetrical convex points are L1, L2, and L3. The lengths of the line segments drawn between symmetrical concave points are l1 and l2. Note that if the number of lobes is odd, the line segments drawn between the concave points and the convex points are nearly parallel to the axis of the short side of the circumscribed rectangle (rectangle).

[0034] Preferably, the irregularity degree 1, which indicates the depth of the leaf portions, is 1.30 to 1.60, and the irregularity degree 2, which indicates the length of the leaf portions, is 1.05 to 1.25. The irregularity degree 1 here is the value obtained by dividing the length (B) of the short side of the circumscribed rectangle (rectangle) by the length of the shortest line segment connecting the recessed points (the shorter of l1 and l2 in Figure 1). By setting the irregularity degree 1 to 1.30 to 1.60, water absorption by capillary action is improved, and the skin's ability to separate during sweating is improved. The irregularity degree 2 is the value obtained by dividing the length (the longer of L2 and L3 in Figure 1) of the second-longest line segment connecting the protruding points on the long side of the circumscribed rectangle (rectangle) and the protruding points symmetrically thereto, by the shortest line segment connecting the recessed points (the shorter of l1 and l2 in Figure 1). By setting the irregularity degree 2 to 1.05 to 1.25, when the knit fabric comes into contact with the skin, it forms a point contact, resulting in a smooth feel. In Figure 1, l1 indicates the length of the shortest line segment among the line segments connecting the concave points, L1 indicates the length of the longest line segment among the line segments connecting the convex points, L2 indicates the length of the second longest line segment among the line segments connecting the convex points, and L3 indicates the length of the third longest line segment among the line segments connecting the convex points.

[0035] The polyamide fiber constituting the knit of the present invention has a single yarn fineness of 0.80 dtex or less. When the single yarn fineness is reduced while maintaining the total fineness, the number of filaments is increased, thereby increasing the contact area of ​​the knit fabric with the skin surface. This significantly improves the cool-to-the-touch feel, which depends on the amount of heat transfer per unit area of ​​the knit fabric. Furthermore, the fiber cross section is flattened and multi-lobed, and the numerous recesses are finer and more numerous, promoting capillary action and improving water absorption, resulting in a soft and smooth feel.

[0036] By using a flattened polyamide fiber with a single yarn fineness within this range, it is possible to achieve a smooth feel, a cool touch, and excellent skin-releasing properties when sweating, making it possible to achieve a comfortable fit even in hot and humid summer environments.

[0037] On the other hand, if the single yarn fineness is too thin, the knit fabric loses its firmness, its ability to stay away from the skin decreases, and its physical strength also decreases, so the preferred single yarn fineness is 0.40 dtex to 0.80 dtex.

[0038] The total fineness of the polyamide fibers constituting the knit of the present invention is preferably 66.0 dtex or less. By setting the total fineness to 66.0 dtex or less, it is possible to design a knit that feels good against the skin. Thin knits are preferred, particularly in hot and humid summer environments, and the thinner the knit, the softer the feel against the skin. Therefore, a more preferred total fineness is 56.0 dtex or less, and even more preferably 44.0 dtex or less. Furthermore, from the viewpoint of being able to knit (manufacture) using the gauge of a general-purpose knitting machine, a preferred range is 15.0 to 44.0 dtex.

[0039] The blending ratio of polyurethane elastic fiber in the knit fabric is preferably 15 to 35% by weight, which allows the knit fabric to have stretch-back properties while providing a high level of coolness to the touch and an extremely smooth wearing comfort.

[0040] The knit of the present invention has a basis weight of 100 g / m ２ ~200g / m ２ The qmax according to the JIS L1927 (2020) cooling sensation evaluation is 0.320 W / cm ２ By setting the weight in this range, even a thin fabric can be obtained with the flat multi-lobed polyamide fiber's characteristics of smooth touch, cool touch, and ability to move away from the skin when sweating, and a comfortable fit can be achieved even in a hot and humid environment in summer. A more preferable weight is 180 g / m ２ Below qmax 0.350 W / cm ２ The upper limit of qmax is preferably higher, but the range that can be realistically manufactured as clothing is 0.700 W / cm ２ The following is the result.

[0041] The knit of the present invention can be knitted using a conventional knitting machine. The fabric structure is not particularly limited, and may be circular knit, weft knit, or warp knit. Preferred circular knit and weft knit structures include plain knit, rib knit, double knit, purl knit, tuck knit, float knit, one-sided rib knit, lace knit, fringe knit, knit miss, and one-sided knot knit. Examples of warp knit structures include single tricot knit, single cord knit, single atlas knit, double tricot knit, double atlas knit, double cord knit, half tricot knit, fleece knit, and jacquard knit. From the perspective of improving the cool-to-the-touch feel by increasing the contact area with the skin, a structure using polyamide fiber and polyurethane elastic fiber in a plain knit or tricot structure with little unevenness on the fabric surface is desirable.

[0042] The knit of the present invention is preferably knitted using a general knitting machine with a gauge of 36 or more from the viewpoint of increasing the contact area with the skin surface. The upper limit is preferably 60 or less.

[0043] The polyamide yarn for producing the knitwear of the present invention will now be described.

[0044] Although it depends on the boiling water shrinkage rate of the polyamide yarn, the preferred single yarn fineness of the polyamide yarn is 0.75 dtex or less. The preferred total fineness of the polyamide yarn is 60 dtex or less. By setting the single yarn fineness and total fineness of the polyamide yarn within the above ranges, the polyamide fibers constituting the knit of the present invention can have a single yarn fineness of 0.80 dtex or less and a total fineness of 66.0 dtex or less.

[0045] The initial elongation stress obtained from a tensile test of the polyamide yarn, that is, from a so-called stress-strain curve, is preferably 0.8 cN / dtex to 1.2 cN / dtex as the stress at 5% elongation.

[0046] The stress at 5% elongation serves as a certain guideline for checking the state of orientation and crystallization during the fiber manufacturing stage. Therefore, by setting the stress at 5% elongation of the polyamide yarn in the present invention to 0.8 cN / dtex or more, uneven dyeing defects in knit fabrics can be suppressed, resulting in high-quality knit fabrics. The stress at 5% elongation of the polyamide yarn is more preferably 0.9 cN / dtex or more, and even more preferably 1.0 cN / dtex or more. On the other hand, the higher the stress at 5% elongation, the relatively lower the elongation of the fiber, which can lead to problems with fuzz in advanced processing steps. For this reason, the stress at 5% elongation of the polyamide yarn is preferably 1.2 cN / dtex or less, which can significantly suppress fuzz defects and result in high-quality knit fabrics.

[0047] The polyamide yarn preferably has an elongation of 35% to 48% from the viewpoint of advanced processing. The polyamide yarn preferably has a strength of 3.0 cN / dtex or more, more preferably 3.5 cN / dtex or more.

[0048] The preferred degree of entanglement of the polyamide yarn is 30 to 50 from the viewpoint of advanced processing. The degree of entanglement here is a value measured by the method described in item 8.15 of JIS L1013 (2021). The lower the degree of entanglement, the more likely it is that fuzz will occur in the advanced processing step, and the higher the degree of entanglement, the narrower the yarn width will be, leading to a streaky appearance on the fabric and poor aesthetics. A more preferred degree of entanglement is 40 to 50.

[0049] The production of polyamide yarn will now be described.

[0050] Compared with polyester fibers, etc., it is difficult to stably spin polyamide fibers while maintaining a special cross-sectional shape, and this difficulty increases particularly as the single yarn size decreases. Therefore, in the production of polyamide yarn to be supplied to the knitwear of the present invention, cross-section formability and spinnability become extremely important.

[0051] Even with the prior art described in Patent Document 3, even when ultra-thin fibers were produced, stable spinning was extremely difficult due to breakage of the fibers discharged from the spinneret due to poor spinnability, and the limit for single fiber fineness was 0.9 dtex. Methods for improving poor spinnability include, for example, increasing the melt temperature to improve the polymer fluidity, or reducing the ratio of the spinneret discharge linear velocity to the take-up speed (hereinafter referred to as the spinning draft) to a spinning draft that ensures spinnability. Increasing the melt temperature, as in the former case, reduces the polymer melt viscosity and increases the ambient temperature directly below the spinneret, causing the fiber cross-sectional shape to approach a circular shape, preventing the desired ultra-thin, flat, multilobal cross-sectional shape from being obtained. Furthermore, reducing the spinning draft, as in the latter case, fails to obtain the desired stress at 5% elongation.

[0052] Therefore, in this invention, the number of threads discharged from the spinneret is significantly increased to three or more threads per spinneret, doubling the amount of polymer flowing into the spinneret compared to the conventional method (i.e., increased discharge rate).By improving the heat carried over by the molten polymer without increasing the melting temperature, the ambient temperature directly below the spinneret is maintained, and the problems of cross-sectional formability and spinnability for special cross-sectional shapes are solved.

[0053] As the melting temperature increases, the fluidity of the polymer improves and spinnability improves, but cross-section formability decreases. Therefore, by appropriately controlling the melting temperature and the ambient temperature directly below the spinneret, good spinnability and cross-section formability can be obtained in polyamide yarn.

[0054] The melting temperature is preferably 20°C to 60°C higher than the melting point of the polyamide. More preferably, the melting temperature is 255°C to 270°C for nylon 6 polymer, 280°C to 295°C for nylon 66 polymer, and 275°C to 290°C for nylon 5,6 polymer. The ambient temperature directly below the spinneret is preferably 220°C to 250°C.

[0055] In order to control the stress at 5% elongation within this range, the spinning draft, which is the value obtained by dividing the take-up speed by the linear discharge speed from the spinneret, is set to 1,500 or more.

[0056] Polyamide yarn can be produced by melt spinning from a nozzle consisting of multiple slits, as shown in Figure 2. The nozzle hole shape of the spinneret is complex, the cross-sectional area of ​​each hole is large, and the linear speed of the spinneret discharge is low, so orientation and crystallization tend to be difficult to achieve. In other words, flat multilobal cross-section fibers tend to have a looser fiber structure than circular cross-section fibers, and when knit fabrics are dyed, uneven dyeing is likely to become very noticeable.

[0057] Therefore, by setting the spinning draft to 1500 or more, orientation crystallization can be promoted, the fiber structure can be made dense, and uneven dyeing can be suppressed. Specifically, the stress at 5% elongation of the polyamide yarn can be controlled to 0.8 cN / dtex to 1.2 cN / dtex. A more preferable spinning draft is 1600 or more.

[0058] Furthermore, when the spinneret discharge linear velocity is low, the tension (spinning tension) applied to the fiber until it is taken up by the take-up roller tends to increase. In other words, stable spinning becomes extremely difficult due to yarn breakage caused by poor spinnability. Therefore, by setting the spinning draft to 1700 or less, the spinning tension becomes stable and spinnability becomes good.

[0059] In polyamide yarn, good spinnability and quality (suppression of uneven dyeing) can be obtained by controlling the spinning draft to 1500 to 1700. In addition, the spinning draft is correlated with the tension applied to the fiber from the time it is discharged from the discharge hole of the spinneret, cooled, and taken up by the take-up roller, and the greater the spinning draft, the greater the tension applied to the fiber (=spinning tension).

[0060] Here, the spinneret discharge linear velocity is the discharge volume of the polymer discharged from the nozzle of the spinneret per unit time divided by the cross-sectional area of ​​the nozzle of the spinneret.

[0061] In order to control the degree of entanglement of the polyamide yarn to a range of 30 to 50, the yarn is entangled using an entanglement device before drawing. Any known entanglement device may be used, and a two-hole, cross-line parallel flow type (EDV nozzle) or a single-hole, inclined flow type (PolyJet nozzle) is preferably used. In the case of a two-hole, cross-line parallel flow type entanglement device, an entanglement nozzle having a jet hole diameter of 0.8 mm to 1 mm, a jet hole angle between the two holes of 100° to 150°, and an inclined jet angle of 0 to 45° relative to the running yarn is preferably used. Furthermore, the compressed air pressure is preferably 0.15 MPa to 0.35 MPa. In the case of a single-hole, inclined flow type entanglement device, an entanglement nozzle having a jet hole diameter of 0.8 mm to 1.5 mm and an inclined jet angle of 0 to 45° is preferably used. Furthermore, the compressed air pressure is preferably 0.10 MPa to 0.30 MPa.

[0062] The knitted fabric thus obtained is comfortable to wear and has a high cool-to-the-touch feel, making it suitable for use in clothing such as innerwear.

[0063] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. First, the measurement methods and evaluation methods used in the present invention will be described.

[0064] A. Fineness (a) Total Fineness of Polyamide Yarn A fiber sample was wound 200 times around a measuring machine with a frame circumference of 1.125 m at a tension of 1 / 30 cN x nominal decitex to prepare a hank. The hank was dried at 105°C for 60 minutes, transferred to a desiccator, and allowed to cool for 30 minutes in an environment of 20°C and 55 RH, and the mass of the hank was measured. The mass per 10,000 m was calculated from the obtained value, and the total fineness of the fiber was calculated using the official moisture regain of 4.5% for nylon 6 and 5.0% for nylon 5,6. The measurement was performed four times, and the average value was taken as the total fineness.

[0065] (b) Total Fineness of Polyamide Fiber (Fabric Decomposition Yarn) Polyamide fiber and polyurethane elastic fiber are decomposed from the knit fabric. Next, the provisional total fineness is calculated to determine the measurement load. A load of 2 g is applied to the polyamide fiber obtained by decomposing the fabric, and the length (L cm) between two points is measured. Then, the fiber is cut at the distance between the two points (L cm) and its weight (W g) is measured, and the provisional total fineness is calculated using the following formula. Next, a load of 1 / 10 g / dtex (0.098 cN / dtex) of the provisional total fineness is applied to the polyamide fiber obtained by decomposing the fabric, and the length and weight between the two points are measured in the same manner as above, and the total fineness is calculated using the following formula. Total Fineness (Decomposition Yarn) = W / L × 100,000 (dtex) (c) Total Fineness of Polyurethane Elastic Fiber (Fabric Decomposition Yarn) Polyamide fiber and polyurethane elastic fiber are decomposed from the knit fabric. The polyurethane elastic fiber obtained by disassembling the fabric was measured for its length (L cm) between two points under no load, and then cut at the distance between the two points (L cm), and its weight (W g) was measured to calculate the total fineness using the following formula: Total fineness (disassembled yarn) = W / L × 100,000 (dtex) (d) Single yarn fineness The total fineness obtained in (a) to (c) above was divided by the number of filaments to obtain the single yarn fineness (dtex).

[0066] B. Strength, elongation, and stress at 5% elongation A tensile strength-elongation curve for polyamide yarn was drawn in accordance with JIS L1013 (2021), item 8.5, Tensile strength and elongation. The test conditions were a constant-speed elongation type testing machine, a grip spacing of 50 cm, and a pulling speed of 50 cm / min. If the tensile strength at break was lower than the maximum strength, the maximum tensile strength and the elongation at that time were measured. The strength, elongation, and stress at 5% elongation were calculated using the following formulas: Strength (cN / dtex) = Tensile strength at break (cN) / Total fineness (dtex) Elongation (%) = Elongation at break (cm) / Grip spacing (cm) x 100 Stress at 5% elongation (cN / dtex) = Tensile strength at 5% elongation (cN) / Total fineness (dtex).

[0067] C. Mixing ratio of polyurethane elastic fiber The knit fabric was measured in accordance with JIS L1030-2 (2012).

[0068] D. Weight The knit fabric was measured in accordance with JIS L1096 (2010), item 8.3 Mass per unit area.

[0069] E. qmax KES-73, Thermo Lab II type, was used, and the temperature of the test room was set to 20°C and 65% RH. In accordance with JIS L1927 (2020), the knitted fabric was placed on the measurement table, and the temperature of the measurement table and the sample material was set to the same as room temperature. The sensor part (heat source part) of the measurement device was set 20°C higher than room temperature and brought into contact with the back side (skin side) of the knitted fabric, and the maximum value of the heat transfer amount at this time was measured in W / cm. ２ was set as qmax.

[0070] F. Cool to the touch The knit fabric was cut into a piece of 30cm x 21cm, and three test subjects rated the cool feeling when they gripped the fabric on a three-point scale from 3 points (excellent) to 1 point (poor), and the average score of the three test subjects was evaluated using the following A to C ratings. A rating and B rating were considered to be cool to the touch. A rating: 3.0 points to 2.7 points: A very cool feeling can be felt. B rating: 2.6 points to 2.3 points: A cool feeling can be felt. C rating: 2.2 points or less: No particular cool feeling can be felt.

[0071] G. Comfort Underwear shirts (crew neck, long sleeve) were sewn using the knit fabric, and five subjects underwent a wearing evaluation. The evaluation method involved sitting for 20 minutes in a room set at 20°C and 65% RH, then moving to another room set at 32°C and 60% RH, performing step-up exercises for 10 minutes, and then moving back to the room at 20°C and 65% RH. After one minute, the subject rated the fabric's adherence to the skin on a three-point scale from 3 points (excellent) to 1 point (poor), and the average score of the five subjects was evaluated using the following A to D scale. A and B were evaluated as good comfort when sweating. A: 3.0 to 2.6 points: no adherence to the skin at all. B: 2.5 to 2.1 points: some adherence to the skin. C: 2.0 to 1.6 points: some uncomfortable adherence to the skin. D rating: 1.5 points to 1.0 points: Uncomfortable sticking to the skin.

[0072] H. Feel to the Skin The knit fabric was cut into a piece of 30 cm x 21 cm and placed on the forearm of three test subjects. The smoothness of the fabric when moved was scored on a three-point scale from 3 points (excellent) to 1 point (poor), and the average score of the three test subjects was evaluated using the following A to C scale. A rating and B rating were considered to indicate good feel to the skin. A rating: 3.0 points to 2.7 points: Very smooth and silky touch. B rating: 2.6 points to 2.3 points: A smooth touch can be felt. C rating: 2.2 points or less: No particular smoothness is felt.

[0073] I. Overall evaluation The evaluation results for cool touch, release and feel were classified according to the following criteria. A and B ratings were given to indicate that the feel is good, that the fabric feels cool when it touches the skin (cool touch), and that the fabric does not stick to the skin when sweating (release), providing a comfortable fit. A rating: All A ratings. B rating: The cool touch rating was B, or either the feel or release was B. C rating: Either the cool touch, the feel or release was C or D.

[0074] J. Fabric Quality To evaluate fabric quality, knit fabrics were inspected under normal reflected light. W0: Good quality with no visible dyeing unevenness W1: Slight dyeing unevenness observed but usable quality W2: Strong dyeing unevenness and unusable quality K. Relative Viscosity After weighing the chip sample, dissolve it in concentrated sulfuric acid (98.0%). Measure the viscosity of a 0.5 wt% solution at 25°C using an Ostwald viscometer.

[0075] L. Cross-sectional shape of polyamide fiber From a cross-sectional photograph (magnification: 400x) of polyamide fiber (textile-decomposed yarn), the following parameters A, B, l1, and L2 were measured for the cross-sectional shapes of all single yarns, as described above, and each parameter was calculated. The average values ​​of the calculated parameters for all single yarns were defined as the flatness, irregularity 1, and irregularity 2 of the polyamide fiber, respectively. A: Length of the long side of the circumscribed quadrangle (rectangle) of the cross-sectional shape B: Length of the short side of the circumscribed quadrangle (rectangle) of the cross-sectional shape l1: Length of the shortest line segment among the line segments connecting the concave points L2: Length of the second longest line segment among the line segments connecting the convex points Flatness = A / B Irregularity 1 = B / l1 Irregularity 2 = B / L2

[0076] M. Degree of entanglement (CF value) Measurement was carried out in accordance with item 8.15 of JIS L1013 (2021). (a) Equipment: Entanglement tester R2040 and electronic tension meter R-1192 (both manufactured by Zelvekar Overseas) (b) Measurement conditions: yarn running speed 2.4 m / min, reel speed 17.6 m / min, reel time 3.4 seconds, reel length 99.7 cm, NO. Show 10 x 10 cm, full scale 25 g (c) Trip tension: (total fineness dtex x 17.64 mN / dtex + total fineness dtex x 88.2 mN / dtex / number of filaments) (d) When the average of the lengths of the individual intertwined points is the average intertwined point length A (mm), the degree of entanglement = 1000 / A. (e) A weight is hung and the machine is run with a predetermined trip tension applied, and the tension indicator is adjusted so that it indicates the initial load. The test counter is set to N=50, and the average value of the measurement results is taken as the degree of entanglement.

[0077] [Example 1] (Production of polyamide yarn) Additive-free nylon 6 chips having a relative viscosity of 3.3 and nylon 6 chips kneaded with 20% by mass of polyvinylpyrrolidone (hereinafter referred to as PVP) were blended to a PVP content of 5% by mass. Chips were used, and the blend was melted at a melting temperature of 265°C and an ambient temperature directly below the spinneret of 220°C (the temperature of the stage heater below the spinneret was set to 220°C), and extruded (41.8 g / min) from a spinneret having 24 nozzles per spinneret (one per yarn), for a total of 144 nozzles (six yarns) as shown in Figure 2(a).

[0078] Next, the yarn was cooled with 18°C ​​cooling air at an internal air-cooled circular cooling device with an upper section air speed of 22 m / min and a lower section air speed of 40 m / min, and after applying oil with an oil supply guide, two yarns were converged and combined at a compressed air pressure of 0.25 MPa using an entanglement device (two-hole cross-line parallel flow type entanglement nozzle (injection hole diameter 0.9 mm, injection hole angle between the two holes 120°, inclined injection angle 0°)). The resulting polyamide yarn had the following physical properties: stress at 5% elongation: 1.1 cN / dtex; strength: 4.8 cN / dtex; elongation: 45%; boiling water shrinkage: 12.0%; and degree of entanglement: 40.

[0079] (Manufacturing of knitwear) The obtained polyamide yarn was used for the front reed, and 22.0 dtex polyurethane elastic fiber (HYOSONG Creora registered trademark H350A) was used for the back reed, and knitting was carried out on a 40-gauge single tricot knitting machine so that the mixing ratio of the polyurethane elastic fiber was 30% by mass, to obtain a tricot greige.

[0080] The obtained tricot grey fabric was subjected to continuous open scouring at 80°C, intermediate setting at 190°C, and dyeing in light blue at 98°C using a milling-type acid dye, and further subjected to finishing setting at 170°C, resulting in a fabric weight of 170 g / m ２ The properties of the knit fabric obtained are shown in Table 1. The knit fabric obtained was excellent in coolness to the touch, texture, and skin-releasing properties, and was fully comfortable to wear and had excellent quality.

[0081] [Example 2] A flat eight-lobe cross section nylon 6 multifilament of 33 dtex and 48 strands was obtained by spinning in the same manner as in Example 1, except that a blend of additive-free chemically recycled nylon 6 chips with a relative viscosity of 3.3 and nylon 6 chips kneaded with 20% by mass of PVP was used to obtain a PVP content of 5% by mass. A knit was produced in the same manner as in Example 1, and a tricot fabric was obtained. The fabric properties are shown in Table 1.

[0082] [Example 3] Nylon 6 chips with a relative viscosity of 2.6 and containing 1.6% by mass of titanium oxide were blended with nylon 6 chips containing 20% ​​by mass of PVP to give a PVP content of 5% by mass. Spinning was performed in the same manner as in Example 1, yielding 48 33 dtex flat octolobal nylon 6 multifilaments. A knit was produced in the same manner as in Example 1, yielding a tricot fabric. The fabric properties are shown in Table 1.

[0083] Example 4: Except for using only additive-free nylon 6 chips with a relative viscosity of 3.3, 48 flat octolobal nylon 6 multifilaments of 33 dtex were obtained by spinning in the same manner as in Example 1. A knit was produced in the same manner as in Example 1 to obtain a tricot fabric, and the fabric properties are shown in Table 1.

[0084] Example 5 A blend of additive-free nylon 5,6 chips with a relative viscosity of 2.8 and nylon 5,6 chips kneaded with 20% by mass of PVP to a PVP content of 5% by mass was used, and spinning was performed in the same manner as in Example 1, except that the melting temperature was 275°C and the ambient temperature directly below the spinneret was 275°C (the stage heater temperature below the spinneret was set to 275°C), resulting in a 33 dtex, 48-strand flat octolobal nylon 5,6 multifilament. A knit was produced in the same manner as in Example 1, and a tricot fabric was obtained. The fabric properties are shown in Table 1.

[0085]

[0086] [Example 6] Spinning was carried out in the same manner as in Example 1, except that the yarn was discharged from a spinneret having 36 holes per spinneret, equivalent to one yarn thread, for a total of 216 holes for six yarn threads, to obtain 72 nylon 6 multifilaments of 33 dtex each. A knit was produced in the same manner as in Example 1 to obtain a tricot fabric, and the fabric properties are shown in Table 2.

[0087] Comparative Example 1 Blend chips similar to those in Example 1 were melted at a melting temperature of 265°C and an ambient temperature directly below the spinneret of 220°C (the temperature of a stage heater below the spinneret was set to 220°C), and extruded (42.2 g / min) from a spinneret having a total of 136 extrusion holes, each of which had 34 holes corresponding to one yarn per spinneret, for a total of four yarns.

[0088] The yarn was then cooled with 18°C ​​cooling air at an upper air speed of 22 m / min and a lower air speed of 40 m / min in an internally blown air-cooled circular cooling device, oiled using an oil supply guide, entangled in an entanglement device, taken up using a first godet roller at 2290 m / min and a spinning draft of 1550, drawn at a draw ratio of 1.7 times, heat set at 155°C, and then wound up at a take-up speed of 4000 m / min to form four 33 dtex, 34 flat octolobal cross section nylon 6 multifilament yarns. A knit was produced in the same manner as in Example 1 to obtain a tricot fabric, and the fabric properties are shown in Table 2.

[0089] Comparative Example 2 Blend chips similar to those in Example 1 were melted at a melting temperature of 265°C and an ambient temperature directly below the spinneret of 220°C (the temperature of a stage heater below the spinneret was set to 220°C), and extruded (42.2 g / min) from a spinneret having a total of 104 nozzle holes, each nozzle hole having 26 nozzle holes (one per yarn) for four yarns, as shown in FIG. 2(a).

[0090] The yarn was then cooled with 18°C ​​cooling air at an upper air speed of 22 m / min and a lower air speed of 40 m / min in an internally blown air-cooled circular cooling device, and after applying an oiling agent through an oil supply guide, was entangled in an entanglement device, taken up with a first godet roller of 2268 m / min and a spinning draft of 1178, stretched at a draw ratio of 1.65 times, and heat set at 155°C. Four yarns of 33 dtex and 26 flat octolobal cross section nylon 6 multifilaments were wound at a take-up speed of 4000 m / min. A knit was produced in the same manner as in Example 1 to obtain a tricot fabric, and the fabric properties are shown in Table 2.

[0091]

[0092] [Example 7] (Production of knitwear) The polyamide fiber (33 dtex, 48 strands of flattened octolobal cross section nylon 6 multifilament) obtained in Example 1 and a 22 dtex polyurethane elastic fiber (HYOSONG Creora registered trademark H350A) were knitted on a 44-gauge single circular knitting machine to obtain a plain jersey (generally also called "bare plain jersey" because it is plain jersey with polyurethane elastic fiber knitted into it). The obtained plain jersey was subjected to refining, dyeing, and finishing in the same manner as in Example 1, and a fabric weight of 105 g / m was obtained. ２ The properties of the knit fabric obtained are shown in Table 3.

[0093] [Example 8] Spinning was performed in the same manner as in Example 1, except that the discharge holes were changed to the one shown in Figure 2(b), to obtain 33 dtex and 48 flat quadrilobular cross section nylon 6 multifilaments. A knit was produced in the same manner as in Example 7, to obtain a jersey fabric. The properties of the obtained knit fabric are shown in Table 3.

[0094] [Example 9] Spinning was performed in the same manner as in Example 1, except that the discharge holes were changed to the one shown in Figure 2(c), to obtain 33 dtex and 48 flat hexa-lobal cross section nylon 6 multifilaments. A knit was produced in the same manner as in Example 7, to obtain a jersey fabric. The properties of the obtained knit fabric are shown in Table 3.

[0095] Comparative Example 3: Spinning was performed in the same manner as in Example 1, except that a rectangular discharge hole (not shown) was used, to obtain 48 flat cross section nylon 6 multifilaments of 33 dtex. A knit was produced in the same manner as in Example 7, to obtain a jersey fabric. The properties of the obtained knit fabric are shown in Table 3.

[0096] Comparative Example 4: Spinning was performed in the same manner as in Example 1, except that a round discharge hole (not shown) was used, to obtain 48 round cross-section nylon 6 multifilaments of 33 dtex. A knit was produced in the same manner as in Example 7, to obtain a jersey fabric. The properties of the obtained knit fabric are shown in Table 3.

[0097]

[0098] [Example 10] A knit was produced in the same manner as in Example 1, except that the yarn feeding tension of the polyurethane elastic fiber was changed, to obtain a tricot fabric containing 16% by mass of polyurethane elastic fiber. The properties of the obtained knit fabric are shown in Table 4.

[0099] [Example 11] A knit was produced in the same manner as in Example 1, except that 11 dtex polyurethane elastic fiber (HYOSONG Creora registered trademark H350A) was used and the yarn feeding tension was changed, to obtain a tricot fabric with a polyurethane elastic fiber content of 30 mass%. The properties of the obtained knit fabric are shown in Table 4.

[0100]

[0101] A: Length of the long side of the circumscribing rectangle (rectangle) of the cross-sectional shape B: Length of the short side of the circumscribing rectangle (rectangle) of the cross-sectional shape L1: Length of the line segment connecting the convex points L2: Length of the line segment connecting the convex points L3: Length of the line segment connecting the convex points l1: Length of the line segment connecting the concave points l2: Length of the line segment connecting the concave points P1 to P8: Convex points Q1 to Q4: Convex points

Claims

1. A knitted fabric made of polyamide fiber and polyurethane elastic fiber, in which the cross-sectional shape of the polyamide fiber single yarn is a flattened multi-lobal shape, and the polyamide fiber single yarn fineness is 0.8 dtex or less.

2. The knitted fabric according to claim 1, wherein the total fineness of the polyamide fibers is 66 dtex or less.

3. A knitted fabric according to claim 1 or 2, wherein the total fineness of the polyurethane elastic fibers is 0.5 to 1.0 times the total fineness of the polyamide fibers.

4. The weight of the knit fabric is 100 g / m ２ ~200g / m ２ The qmax according to the JIS L1927 (2020) cooling sensation evaluation is 0.320 W / cm ２ The knitted fabric according to claim 1 or 2, wherein the knitted fabric is a knitted fabric having the above structure.

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