Three-dimensional crimped yarn and preparation method therefor

Abstract

A three-dimensional crimped yarn and a preparation method therefor. The three-dimensional crimped yarn is formed by alternately and continuously arranging a knitted front stitch group and a knitted reverse stitch group, and is in a three-dimensional crimped form having different crimping directions, wherein the knitted front stitch group includes one or more continuously arranged knitted front stitches (11), and the knitted reverse stitch group includes one or more continuously arranged knitted reverse stitches (12). The three-dimensional crimped yarn is formed by alternately arranging the knitted front stitch group and the knitted reverse stitch group, is in a three-dimensional crimped form having different crimping directions, and thus has full hand feeling, good fluffiness and high elasticity, and the crimped form of the three-dimensional crimped yarn can also improve the cohesive force during fiber processing and the dimensional stability of fabrics.

Description

Three-dimensional curled yarn and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of textile product manufacturing, in particular to a crimped yarn and a preparation method thereof. Background Art

[0002] Wool is a key raw material in the textile industry, offering excellent warmth, elasticity, and high hygroscopicity. It is a naturally three-dimensional, crimped fiber. However, due to its limited production and high cost, its use is currently limited to high-end textiles. Imparting a three-dimensional crimped morphology to synthetic fibers, thereby producing fibers with wool-like bulk and warmth, is a key research area and a pressing challenge in the textile industry.

[0003] Currently, various methods for producing crimped synthetic fibers have been reported, including spinning methods such as bicomponent composite spinning and asymmetric cooling molding, as well as physical heating methods such as stuffing box and debonding. For example, Chinese Invention Publication No. CN111575830A provides a method for producing self-crimping polyester filaments. The crimped filaments comprise polybutylene terephthalate chips as the hollow structure component, and composite resin and flame-retardant masterbatch as the solid structure component. The two components are composite-spun to produce self-crimping polyester filaments with excellent breaking strength, elongation at break, and flame retardancy. Chinese Invention No. CN102691117B provides a process for preparing three-dimensional crimped hollow polyester staple fibers. During the melt cooling molding process of the spinning process, the hollow fibers are produced by adopting a low-temperature spinning process, a quenching process of the filaments, and a special annular air filter. This results in instantaneous cooling of the melt ejected from the spinneret. Due to the differential cooling across the fiber cross-section, a spiral-shaped, crimped hollow fiber is formed longitudinally.

[0004] Chinese invention CN101198731B discloses a stuffer-box crimping machine and crimping method, as well as a method for producing cellulose acetate tow using the crimping machine. The stuffer-box crimping machine comprises a pair of rollers, a pair of scrapers, and a stuffer box, wherein the stuffer box includes a stuffer-box trough constructed of a hard material with a surface hardness of at least 60 Rc. The crimped yarn disclosed in US Patent Application No. 3330018A is a crimped yarn that is first knitted into a cylindrical fabric with alternating plain weave and floats using a debonding method. After heat setting, the yarn is then debonded and debonded into a crimped yarn with alternating crimped and straight sections. This yarn exhibits a continuous, regular, and evenly spaced crimp pattern, making it suitable for weaving wrinkled fabrics with a convex-concave effect and a distinctive style.

[0005] However, although the use of two-component composite spinning method and asymmetric cooling forming method can obtain fibers with good curling effect, such methods have complex process flow, high investment cost and great production difficulty; and the curled fibers produced by the stuffer box curling method can only be sawtooth waves, with poor fluffiness and resilience, which cannot meet the development needs of new products; the unbraiding deformation method has simple equipment and short process flow, and is an economical and convenient method for producing curled yarns, but in this method, the woven fabrics are all plain weaves. After heat setting and detangling, the coils obtained from such fabrics have limited bending degree and poor spatial three-dimensionality, and the curled shape of the yarn is easily destroyed during conventional detangling and curling.

[0006] Summary of the Invention

[0007] One object of the present invention is to overcome the deficiencies of the prior art and provide a three-dimensional crimped yarn with good bulkiness;

[0008] Another object of the present invention is to provide a method for preparing three-dimensional crimped yarn with simple process.

[0009] According to one aspect of the present invention, the present invention provides a three-dimensional curled yarn, which is formed by alternating and continuously arranging a knitted front coil group and a knitted back coil group to form a three-dimensional curled form with different bending directions, wherein the knitted front coil group includes one or more continuously arranged knitted front coils, and the knitted back coil group includes one or more continuously arranged knitted back coils.

[0010] According to one embodiment of the present invention, the knitted front coil group includes 1-3 knitted front coils, and the knitted back coil group includes 1-3 knitted back coils.

[0011] According to one embodiment of the present invention, the three-dimensional crimped yarn is a thermoplastic yarn.

[0012] According to one embodiment of the present invention, the three-dimensional curled yarn is a polylactic acid yarn, and the linear density of the polylactic acid yarn is 50D-1200D.

[0013] According to another aspect of the present invention, the present invention provides a method for preparing a three-dimensional crimped yarn, comprising the following steps:

[0014] S1, providing a thermoplastic yarn raw material, and knitting the thermoplastic yarn into a knitted fabric with a double-sided knitted structure on a weft knitting machine, wherein the knitted fabric is formed by alternatingly arranging a knitted front coil group and a knitted back coil group, wherein the knitted front coil group includes one or more continuously arranged knitted front coils, and the knitted back coil group includes one or more continuously arranged knitted back coils;

[0015] S2, heat setting the knitted fabric;

[0016] S3, unweaving the heat-set knitted fabric into three-dimensional curly yarns, and then winding the three-dimensional curly yarns uniformly and layer by layer onto a yarn drum while maintaining the curly shape.

[0017] According to one embodiment of the present invention, the double-sided knitted structure is a rib structure or a knitted structure including a rib structure.

[0018] According to one embodiment of the present invention, the heat setting method includes dry heat setting and wet heat setting, and the heat setting temperature is higher than the glass transition temperature of the yarn raw material and lower than the melting temperature of the yarn raw material.

[0019] According to one embodiment of the present invention, the yarn raw material is polylactic acid, the heat setting temperature is 80°C-160°C, and the heat setting time is not less than 20 seconds. Preferably, the heat setting temperature is 120°C, and the heat setting time is 90 seconds.

[0020] According to one embodiment of the present invention, in step S3, a de-knitting and de-raveling device is used to de-knit and de-ravel the heat-set knitted fabric into three-dimensional curly yarn and wind it up. The de-knitting and de-raveling device includes a front roller, a rear roller and a yarn drum working with the rear roller. The yarn is de-knitted from the heat-set knitted fabric, and the yarn passes through the front roller and the rear roller in sequence and is wound onto the yarn drum, wherein the rotational linear speed of the front roller is greater than the rotational linear speed of the yarn drum.

[0021] According to one embodiment of the present invention, the rotational linear speed of the front roller is 1.1-2.0 times greater than the rotational linear speed of the back roller.

[0022] According to one embodiment of the present invention, the de-knitting and de-raveling device further comprises a rotatable yarn guide disposed between the front roller and the back roller, wherein the yarn guide is used for guiding and transmitting the yarn.

[0023] According to one embodiment of the present invention, the step of cutting the prepared three-dimensional crimped yarn into short fibers is also included. As can be seen from the above technical solution, the advantages and positive effects of the present invention are:

[0024] The method for preparing the three-dimensional curly yarn provided by the present invention first weaves the yarn raw material into a knitted fabric with a double-sided knitted structure, and after heat setting, unweaves and detangles the knitted fabric into three-dimensional curly yarn, and winds the curly yarn evenly and layer by layer onto a yarn drum while maintaining the curly shape. The method for preparing the three-dimensional curly yarn provided by the present invention is simple to operate, low in cost, and easy to implement. During the production process, there is no need to use large equipment such as melt spinning machines and to control complex asymmetric cooling conditions. The three-dimensional curly yarn of the present invention is formed by alternatingly arranging a knitted front coil group and a knitted back coil group to form a three-dimensional curly form with different bending directions. It not only has a plump hand feel, good fluffiness, and high elasticity, but its curly form can also improve the cohesive force during fiber processing and the dimensional stability of the fabric. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the accompanying drawings.

[0026] FIG1 is a schematic structural diagram of a three-dimensional crimped yarn according to the present invention.

[0027] FIG2 is a schematic structural diagram of a de-knitting and de-raveling device in the method for preparing three-dimensional crimped yarn according to the present invention.

[0028] FIG3 is a flow chart of the method for preparing a three-dimensional crimped yarn according to the present invention.

[0029] FIG4 is a schematic diagram showing a double-sided knitting structure in the first embodiment of the method for preparing a three-dimensional crimped yarn according to the present invention.

[0030] FIG5 is a schematic diagram showing a double-sided knitting structure in a second embodiment of the method for preparing a three-dimensional curled yarn according to the present invention.

[0031] FIG6 is a schematic diagram showing a double-sided knitting structure in a third embodiment of the method for preparing a three-dimensional curled yarn according to the present invention.

[0032] FIG7 shows a schematic diagram of a double-sided knitting structure in a fourth embodiment of the method for preparing a three-dimensional curled yarn according to the present invention.

[0033] FIG8 is a schematic diagram showing a plain knitting structure in an existing method for preparing crimped yarn. DETAILED DESCRIPTION

[0034] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be embodied in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent like or similar structures, and thus their detailed description will be omitted.

[0035] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0036] In the description of the embodiments of the invention, it should be understood that the terms "first", "second" and "third" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise expressly defined. Terms such as "installed", "connected", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. The directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", and "rear" are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the invention and simplifying the description, and are not to indicate or imply that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the embodiments of the invention.

[0037] As shown in Figure 1, the three-dimensional crimped yarn of the present invention is formed by alternating and continuously arranged groups of knitted face and back stitches, creating a three-dimensional crimped shape with different bending directions. The knitted face and back stitches are arranged continuously, meaning there are no straight floating threads between the face and back stitches.

[0038] Each knitted front coil group includes one knitted front coil 11, or includes multiple, for example, 3 knitted front coils 11. When there are multiple knitted front coils 11 in each knitted front coil group, these knitted front coils 11 are arranged continuously, that is, there is no straight floating line between two adjacent knitted front coils 11; each knitted back coil group includes one knitted back coil 12, or includes multiple, for example, 3 knitted back coils 12. When there are multiple knitted back coils 12 in each knitted front coil group, these knitted back coils 12 are arranged continuously, that is, there is no straight floating line between two adjacent knitted back coils 12.

[0039] The three-dimensional curled yarn of the present invention has no straight floating lines, but is composed of multiple tightly arranged outer knitted coils. The coils are dense and have a high degree of curvature. The curvature direction of the knitted front coil 11 is different from that of the knitted back coil 12. Therefore, it has good three-dimensionality and excellent fluffiness.

[0040] Referring to Figure 1, Figure 1 only illustrates a case where a knitted front coil group includes only one knitted front coil 11 and a knitted back coil group includes only one knitted back coil 12. In this case, the three-dimensional coiled yarn is composed of one knitted front coil 11 and one knitted back coil 12 arranged alternately and continuously. In other embodiments, the three-dimensional coiled yarn may be composed of two knitted front coils 11 and one knitted back coil 12 arranged alternately and continuously, or one knitted front coil 11 and three knitted back coils 12 arranged alternately and continuously, or three knitted front coils 11 and four knitted back coils 12 arranged alternately and continuously, and so on. In short, the number of knitted front coils 11 in each knitted front coil group and the number of knitted back coils 12 in each knitted back coil group are not specifically limited and may be appropriately increased or decreased based on design requirements.

[0041] The raw material of the three-dimensional curly yarn of the present invention is preferably thermoplastic yarn to facilitate heat setting. For example, the raw material of the three-dimensional curly yarn of the present invention is polylactic acid yarn, the linear density of the polylactic acid yarn can be in the range of 50D-1200D, and the cross-sectional shape of the polylactic acid yarn can be circular, elliptical, hollow ring or special-shaped cross-section, etc. Polylactic acid fiber is made from starch-rich herbaceous plants (such as corn, cassava), and is first produced by biological methods such as saccharification, fermentation, purification, and polymerization to produce polylactic acid, and then made by melt spinning. The source of polylactic acid raw materials is abundant, the production process is environmentally friendly and non-toxic, and the related products can be degraded into carbon dioxide and water after being discarded, which is harmless to the environment. It is a new type of green fiber. Polylactic acid fiber not only has the natural characteristics of environmental compatibility and biodegradability, but the fabric made of polylactic acid yarn also has the excellent properties of good warmth retention, good flame retardancy, comfortable hand feel, skin-friendly and antibacterial, and has high economic value. The eco-friendly three-dimensional curly yarn made from polylactic acid yarn raw material has multiple different buckling directions. It not only feels plump, fluffy and elastic, but its curly shape can also improve the cohesion during fiber processing and the dimensional stability of the fabric. It can be used to replace natural curly wool fiber with limited production and high price.

[0042] The following describes the de-knitting and de-dispersing device used in the method for preparing three-dimensional curled yarn of the present invention. As shown in Figure 2, the de-knitting and de-dispersing device includes a front roller, a rear roller, and a yarn drum 40. The front roller includes a pair of front rollers 20 that work in conjunction with each other, wherein one front roller 20 is driven to rotate by a motor, and the other front roller 20 rotates accordingly; the rear roller includes a rotatable rear roller 30, which can be driven to rotate by a motor, and the yarn drum 40 works in conjunction with the rear roller 30 and rotates accordingly. In some embodiments, the yarn drum 40 can also move back and forth along its central axis. Furthermore, the de-knitting and de-dispersing device also includes a yarn guide 50, which is rotatably arranged between the front roller and the rear roller for guiding and transmitting the yarn.

[0043] Referring to FIG3 , the method for preparing the three-dimensional crimped yarn of the present invention comprises the following steps:

[0044] S1, providing a thermoplastic yarn raw material, and knitting the thermoplastic yarn on a weft knitting machine into a knitted fabric having a double-sided knitted structure, wherein the knitted fabric is formed by alternatingly arranging a knitted front coil group and a knitted back coil group, wherein the knitted front coil group includes one or more continuously arranged knitted front coils 11, and the knitted back coil group includes one or more continuously arranged knitted back coils 12; the double-sided knitted structure is a rib structure or a modified rib structure containing a rib structure;

[0045] S2, heat-setting the knitted fabric, wherein the heat-setting method includes dry heat setting and wet heat setting, and the heat-setting temperature is higher than the glass transition temperature of the yarn material and lower than the melting temperature of the yarn material. When the yarn material is polylactic acid, the heat-setting temperature is 80° C.-160° C., and the heat-setting time is not less than 20 seconds, preferably 120° C. and 90 seconds.

[0046] S3, unweaving the heat-set knitted fabric into three-dimensional curly yarn, and then winding the three-dimensional curly yarn evenly and layer by layer onto a yarn bobbin while maintaining the curly shape.

[0047] The method for preparing the three-dimensional curly yarn of the present invention adopts a knitting false braiding technique, that is, the yarn raw material is first spun into a knitted fabric, which is then heat-set and then unraveled to obtain the three-dimensional curly yarn. The knitted fabric is a double-sided knitted structure, comprising knitted front coils and knitted back coils with different bending directions and arranged continuously. After heat-setting, it is unraveled and unraveled into a three-dimensional curly yarn. The three-dimensional curly yarn comprises dense coils with multiple bending directions and has excellent elasticity, fluffiness and thermal insulation properties. The process of winding the three-dimensional curly yarn onto the yarn bobbin is to maintain the curly shape and to wind it evenly and layer by layer to prevent the coils from becoming straight. The method for preparing the three-dimensional curly yarn of the present invention is simple to operate and easy to implement, and can prepare a three-dimensional curly yarn similar to high-quality natural wool.

[0048] Furthermore, the method for preparing three-dimensional curly yarn of the present invention uses the aforementioned de-knitting and de-dispersing device to de-knit and de-disperse the heat-set knitted fabric into three-dimensional curly yarn and wind it onto a yarn drum. The rotational linear speed of the front roller is greater than the rotational linear speed of the yarn drum. Preferably, the rotational linear speed of the front roller is greater than 1.1-2.0 times the rotational linear speed of the yarn drum. In the method of the present invention, due to the speed difference between the rotational linear speeds of the yarn drum and the front roller, it can be ensured that the yarn is not straightened during the winding process onto the yarn drum, but can maintain a curly state; the yarn guide 50 in the de-knitting and de-dispersing device can not only guide the yarn transmission, but also feed the yarn into the winding area of ​​the yarn drum in time through its own rotation to avoid the knitted coils from being stretched; as the yarn drum moves back and forth uniformly along its axis, the yarn with the curly coils can be evenly wound onto the yarn drum layer by layer.

[0049] The following are examples of the method for preparing the three-dimensional crimped yarn of the present invention.

[0050] Example 1

[0051] 2 and 3 , the method for preparing the three-dimensional crimped yarn in Example 1 of the present invention uses 50D polylactic acid filaments with a circular cross-section as the yarn raw material, and includes the following steps:

[0052] S1, knitting the 50D polylactic acid filaments with a circular cross-section into a full-needle rib fabric on a computerized flat knitting machine, as shown in FIG4 ;

[0053] S2, dry-heat setting the woven polylactic acid fabric at 80°C for 100s;

[0054] S3, de-knitting and de-raveling the heat-set polylactic acid fabric into three-dimensional curly yarn on a de-knitting and de-raveling device, and then winding it onto a yarn drum evenly and layer by layer, wherein the de-knitting linear speed of the front roller, i.e., the rotation linear speed, is 2.0 times the yarn drum winding linear speed.

[0055] Example 2

[0056] The method for preparing the three-dimensional crimped yarn in Example 2 of the present invention uses a 75D polylactic acid filament with a circular cross-section as the yarn raw material, and comprises the following steps:

[0057] S1, knitting the 75D polylactic acid filaments with a circular cross-section into a 1×1 rib fabric on a computerized flat knitting machine, as shown in FIG5 ;

[0058] S2, dry-heat setting the woven polylactic acid fabric at 100°C for 100s;

[0059] S3, de-knitting and de-raveling the heat-set polylactic acid fabric into three-dimensional curly yarn on a de-knitting and de-raveling device, and then winding it onto a yarn drum evenly and layer by layer, wherein the de-knitting speed of the front roller, i.e., the rotation speed, is 1.8 times the winding speed of the yarn drum.

[0060] Example 3

[0061] The method for preparing the three-dimensional crimped yarn in Example 3 of the present invention uses a 150D polylactic acid filament with a circular cross-section as the yarn raw material, and comprises the following steps:

[0062] S1, knitting the 150D polylactic acid filaments with a circular cross-section into a 1×1 rib fabric on a computerized flat knitting machine;

[0063] S2, dry-heat setting the woven polylactic acid fabric at 120°C for 80s;

[0064] S3, de-knitting and de-raveling the heat-set polylactic acid fabric into three-dimensional curly yarn on a de-knitting and de-raveling device, and then winding it onto a yarn drum evenly and layer by layer, wherein the de-knitting speed of the front roller, i.e., the rotation speed, is 1.6 times the winding speed of the yarn drum.

[0065] Example 4

[0066] The method for preparing the three-dimensional crimped yarn in Example 4 of the present invention uses a 300D polylactic acid filament with a circular cross-section as the yarn raw material, and comprises the following steps:

[0067] S1, knitting the 300D polylactic acid filaments with a circular cross-section into a full-needle rib fabric on a computerized flat knitting machine;

[0068] S2, dry-heat setting the woven polylactic acid fabric at 120°C for 90s;

[0069] S3, de-knitting and de-raveling the heat-set polylactic acid fabric into three-dimensional curly yarn on a de-knitting and de-raveling device, and then winding it onto a yarn drum evenly and layer by layer, wherein the de-knitting speed of the front roller, i.e., the rotation speed, is 1.6 times the winding speed of the yarn drum.

[0070] Example 5

[0071] The method for preparing the three-dimensional crimped yarn in Example 5 of the present invention uses a 300D polylactic acid filament with a triangular cross-section as the yarn raw material, and comprises the following steps:

[0072] S1, knitting the 300D polylactic acid filaments with a triangular cross-section into a 1×1 rib fabric on a computerized flat knitting machine;

[0073] S2, wet-heat setting the woven polylactic acid fabric at 120°C for 60s;

[0074] S3, de-knitting and de-raveling the heat-set polylactic acid fabric into three-dimensional curly yarn on a de-knitting and de-raveling device, and then winding it onto a yarn drum evenly and layer by layer, wherein the de-raveling speed of the front roller is 1.5 times the winding speed of the yarn drum.

[0075] Example 6

[0076] The method for preparing the three-dimensional crimped yarn in Example 6 of the present invention uses a 300D polylactic acid filament with a cross-shaped cross section as the yarn raw material, and comprises the following steps:

[0077] S1, knitting the 300D polylactic acid filaments with a cross-shaped cross section into a 2×1 rib fabric on a computerized flat knitting machine, as shown in FIG6 ;

[0078] S2, dry-heat setting the woven polylactic acid fabric at 160°C for 20s;

[0079] S3, de-knitting and de-raveling the heat-set polylactic acid fabric into three-dimensional curly yarn on a de-knitting and de-raveling device, and then winding it onto a yarn drum evenly and layer by layer, wherein the de-raveling speed of the front roller is 1.5 times the winding speed of the yarn drum.

[0080] Example 7

[0081] The preparation method of the three-dimensional crimped yarn of Example 7 of the present invention uses a yarn raw material of hollow 300D polylactic acid filament, comprising the following steps:

[0082] S1, knitting the hollow 300D polylactic acid filament into a 2×2 rib fabric on a computerized flat knitting machine, as shown in FIG7 ;

[0083] S2, dry-heat setting the woven polylactic acid fabric at 100°C for 100s;

[0084] S3, de-knitting and de-raveling the heat-set polylactic acid fabric into three-dimensional curly yarn on a de-knitting and de-raveling device, and then winding it onto a yarn drum evenly and layer by layer, wherein the de-raveling speed of the front roller is 1.5 times the winding speed of the yarn drum.

[0085] Example 8

[0086] The method for preparing the three-dimensional crimped yarn in Example 8 of the present invention uses a yarn raw material of 450D polylactic acid filament with a circular cross-section, comprising the following steps:

[0087] S1, knitting the 450D polylactic acid filaments with a circular cross-section into a 1×1 rib fabric on a computerized flat knitting machine;

[0088] S2, dry-heat setting the woven polylactic acid fabric at 120°C for 90s;

[0089] S3, unweaving and unraveling the heat-set polylactic acid fabric into three-dimensional curly yarn on a unweaving and unraveling device, and then winding it onto a yarn drum evenly and layer by layer, wherein the unraveling speed of the front roller is 1.4 times the winding speed of the yarn drum.

[0090] Example 9

[0091] The method for preparing the three-dimensional crimped yarn in Example 9 of the present invention uses a 600D polylactic acid filament with a circular cross-section as the yarn raw material, and comprises the following steps:

[0092] S1, knitting the 600D polylactic acid filaments with a circular cross-section into a 1×1 rib fabric on a computerized flat knitting machine;

[0093] S2, dry-heat setting the woven polylactic acid fabric at 120°C for 90s;

[0094] S3, de-knitting and de-raveling the heat-set polylactic acid fabric into three-dimensional curly yarn on a de-knitting and de-raveling device, and then winding it onto a yarn drum evenly and layer by layer, wherein the de-raveling speed of the front roller is 1.3 times the winding speed of the yarn drum.

[0095] Example 10

[0096] The method for preparing the three-dimensional crimped yarn in Example 10 of the present invention uses a 900D polylactic acid filament with a circular cross-section as the yarn raw material, and comprises the following steps:

[0097] S1, knitting the 900D polylactic acid filaments with a circular cross-section into a full-needle rib fabric on a computerized flat knitting machine;

[0098] S2, dry-heat setting the woven polylactic acid fabric at 140°C for 60s;

[0099] S3, de-knitting and de-raveling the heat-set polylactic acid fabric into three-dimensional curly yarn on a de-knitting and de-raveling device, and then winding it onto a yarn drum evenly and layer by layer, wherein the de-knitting speed of the front roller, i.e., the rotation speed, is 1.3 times the winding speed of the yarn drum.

[0100] Example 11

[0101] The method for preparing the three-dimensional crimped yarn in Example 11 of the present invention uses a 1200D polylactic acid filament with a circular cross-section as the yarn raw material, and comprises the following steps:

[0102] S1, knitting the 1200D polylactic acid filaments with a circular cross-section into a full-needle rib fabric on a computerized flat knitting machine;

[0103] S2, dry-heat setting the woven polylactic acid fabric at 160°C for 100s;

[0104] S3, de-knitting and de-raveling the heat-set polylactic acid fabric into three-dimensional curly yarn on a de-knitting and de-raveling device, and then winding it onto a yarn drum evenly and layer by layer, wherein the de-knitting linear speed of the front roller, i.e., the rotation linear speed, is 1.1 times the yarn drum winding linear speed.

[0105] Example 12

[0106] The method for preparing the three-dimensional crimped yarn in Example 12 of the present invention uses 300D polyester filament with a circular cross-section as the yarn raw material, and comprises the following steps:

[0107] S1, knitting the circular cross-section 300D polyester filament into a full-needle rib fabric on a computer flat knitting machine;

[0108] S2, wet-heat setting the woven polyester fabric at 160°C for 30s;

[0109] S3, de-knitting and de-raveling the heat-set polyester fabric into three-dimensional curly yarn on a de-knitting and de-raveling device, and then winding the three-dimensional curly yarn evenly and layer by layer onto a yarn drum, wherein the de-raveling speed of the front roller is 1.5 times the winding speed of the yarn drum.

[0110] Example 13

[0111] The method for preparing the three-dimensional crimped yarn in Example 8 of the present invention uses 300D lyocell filaments with a circular cross-section as the yarn raw material, and comprises the following steps:

[0112] S1, knitting the 300D lyocell filament with a circular cross-section into a full-needle rib fabric on a computer flat knitting machine;

[0113] S2, wet-heat setting the woven lyocell fabric at 160°C for 30s;

[0114] S3, de-knitting and de-raveling the heat-set lyocell fabric into three-dimensional crimped yarns on a de-knitting and de-raveling device, and then winding the yarns evenly and layer by layer onto a bobbin, wherein the de-raveling speed of the front roller is 1.5 times the winding speed of the bobbin.

[0115] In other embodiments, the prepared three-dimensional curled yarn can be further cut into short fibers to expand its use in textile filling materials, such as as filling fiber for down jackets, sleeping bags, pillow cores, mattresses and soft toys.

[0116] Comparative Example 1

[0117] Comparative Example 1 is a method for preparing a crimped yarn, which uses 300D polylactic acid filaments with a circular cross-section as a yarn raw material and is prepared according to the following method:

[0118] S1, knitting the 300D polylactic acid filaments with a circular cross section into a plain knitted fabric on a computerized flat knitting machine, see FIG8 ;

[0119] S2, dry-heat setting the woven polylactic acid fabric at 120°C for 90s;

[0120] S3, unraveling the heat-set polylactic acid fabric on a conventional pineapple spindle winding machine without adding tension, and then winding it onto a yarn bobbin.

[0121] Comparative Example 2

[0122] Comparative Example 2 is a method for preparing a crimped yarn, which uses 450D polylactic acid filaments with a circular cross-section as a yarn raw material and is prepared according to the following method:

[0123] S1, knitting the 450D polylactic acid filaments with a circular cross-section into a plain knit fabric on a computerized flat knitting machine;

[0124] S2, dry-heat setting the woven polylactic acid fabric at 120°C for 90s;

[0125] S3, unraveling the heat-set polylactic acid fabric on a conventional pineapple spindle winding machine without adding tension, and then winding it onto a yarn bobbin.

[0126] Comparative Example 3

[0127] Comparative Example 3 is a method for preparing a crimped yarn, which uses 600D polylactic acid filaments with a circular cross-section as a yarn raw material and is prepared according to the following method:

[0128] S1, knitting the 600D polylactic acid filaments with a circular cross-section into a plain knit fabric on a computerized flat knitting machine;

[0129] S2, dry-heat setting the woven polylactic acid fabric at 120°C for 90s;

[0130] S3, unraveling the heat-set polylactic acid fabric on a conventional pineapple spindle winding machine without adding tension, and then winding it onto a yarn bobbin.

[0131] The crimp and bulk properties of the eleven three-dimensional crimped yarns described in the above examples and comparative examples were tested in accordance with the crimp performance test method specified in the standard GB / T 14338-2008 "Test Method for Crimping of Chemical Staple Fibers" and the bulk performance test method specified in the standard FZ / T 50009.4-2019 "Test Method for Bulkiness and Elasticity of Hollow Polyester Staple Fibers." The specific test results are shown in the following table:

[0132] The crimp number refers to the number of curls per unit length of yarn, while the curl rate is the degree of shortening of the yarn after curling. The crimp number and curl rate of three-dimensional coiled filaments prepared by the de-knitting deformation method are closely related to the coil length of the knitted fabric. The shorter the coil length of the knitted fabric, the greater the crimp number and curl rate of the de-knitted three-dimensional coiled yarn, and vice versa. That is, the curling performance of three-dimensional coiled filaments can be improved by adjusting the coil length of the knitted fabric. As can be seen from the test results of the embodiments of the present invention and the comparative examples, the three-dimensional coiled yarns of the embodiments of the present invention generally have better bulk performance than the comparative examples.

[0133] For example, the yarn raw materials, linear density and coil length of Example 4 of the present invention and Comparative Example 1 are the same, the bulkiness of Example 4 of the present invention is 53.28%, while the bulkiness of Comparative Example 1 is 52.72%; similarly, under the same conditions, the bulkiness of Example 8 of the present invention is 54.69%, while the bulkiness of Comparative Example 2 is 52.99%; the bulkiness of Example 9 of the present invention is 56.48%, while the bulkiness of Comparative Example 3 is 53.28%.

[0134] The three-dimensional crimped filaments obtained by unbraiding ribbed and its variants (woven fabrics containing ribs) exhibit superior bulk compared to those obtained by unbraiding plain weave. This is because the coils in plain weave are directional, and the crimped yarns obtained by unbraiding plain weaves are only unidirectional. However, the coils in ribbed and its variants bend in different directions, resulting in a bidirectional crimped morphology and a higher three-dimensionality.

[0135] The above are merely preferred embodiments of the invention and are not intended to limit the embodiments of the invention. Those skilled in the art will readily appreciate that various modifications and variations of the embodiments of the invention are possible. Any modifications, equivalent substitutions, and improvements that fall within the spirit and principles of the claims shall be included within the scope of protection of the claims.

Claims

1. A three-dimensional curled yarn, characterized in that: The three-dimensional curled yarn is composed of a knitted front coil group and a knitted back coil group arranged alternately and continuously to form a three-dimensional curled shape with different bending directions, wherein the knitted front coil group includes one or more continuously arranged knitted front coils, and the knitted back coil group includes one or more continuously arranged knitted back coils.

2. The three-dimensional crimped yarn according to claim 1, characterized in that: The knitted front coil group includes 1-3 knitted front coils, and the knitted back coil group includes 1-3 knitted back coils.

3. The three-dimensional crimped yarn according to claim 1 or 2, characterized in that: The three-dimensional curled yarn is a thermoplastic yarn.

4. The three-dimensional crimped yarn according to claim 3, characterized in that: The three-dimensional curled yarn is polylactic acid yarn, and the linear density of the polylactic acid yarn is 50D-1200D.

5. A method for preparing a three-dimensional curled yarn, characterized in that: The following steps are involved: S1, providing a thermoplastic yarn raw material, and knitting the thermoplastic yarn into a knitted fabric with a double-sided knitted structure on a weft knitting machine, wherein the knitted fabric is formed by alternatingly arranging a knitted front coil group and a knitted back coil group, wherein the knitted front coil group includes one or more continuously arranged knitted front coils, and the knitted back coil group includes one or more continuously arranged knitted back coils; S2, heat setting the knitted fabric; S3, unbraiding the heat-set knitted fabric to form three-dimensional curly yarns, and then winding the three-dimensional curly yarns uniformly and layer by layer onto a yarn tube while maintaining the curly shape.

6. The method for preparing a three-dimensional crimped yarn according to claim 5, characterized in that: The double-sided knitted structure is a rib structure or a knitted structure including a rib structure.

7. The method for preparing a three-dimensional crimped yarn according to claim 5, characterized in that: The heat setting method includes dry heat setting and wet heat setting. The heat setting temperature is higher than the glass transition temperature of the yarn raw material and lower than the melting temperature of the yarn raw material.

8. The method for preparing a three-dimensional crimped yarn according to claim 5, characterized in that: The yarn raw material is polylactic acid, the heat setting temperature is 80° C.-160° C., and the heat setting time is not less than 20 seconds.

9. The method for preparing a three-dimensional crimped yarn according to claim 8, characterized in that: The heat setting temperature is 120° C., and the heat setting time is 90 seconds.

10. The method for preparing a three-dimensional crimped yarn according to any one of claims 5 to 9, characterized in that: In step S3, a de-knitting and de-raveling device is used to de-knit and de-ravel the heat-set knitted fabric into three-dimensional curly yarn and wind it up. The de-knitting and de-raveling device includes a front roller, a rear roller and a yarn drum working with the rear roller. The yarn is de-knitted from the heat-set knitted fabric, and the yarn passes through the front roller and the rear roller in sequence and is wound onto the yarn drum, wherein the rotational linear speed of the front roller is greater than the rotational linear speed of the yarn drum.

11. The method for preparing a three-dimensional crimped yarn according to claim 10, characterized in that: The rotational linear speed of the front roller is 1.1-2.0 times greater than the rotational linear speed of the rear roller.

12. The method for preparing a three-dimensional crimped yarn according to claim 10, characterized in that: The de-knitting and de-raveling device further comprises a rotatable yarn guide arranged between the front roller and the rear roller, wherein the yarn guide is used for guiding and transmitting the yarn.

13. The method for preparing a three-dimensional crimped yarn according to any one of claims 5 to 9, characterized in that: The method also includes the step of cutting the prepared three-dimensional crimped yarn into short fibers.

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