Single-strand untwisted yarn and method for producing same

Abstract

This invention relates to the field of textile technology, and particularly to a single-strand untwisted yarn and its preparation method. The preparation method includes a step of heating a pre-twisted single-strand filament to make it thermoplastic; and a step of sequentially untwisting and reverse-twisting the thermoplastic single-strand filament; wherein the direction of untwisting is opposite to the pre-twisting direction, and the direction of reverse-twisting is the same as the pre-twisting direction; the D / Y ratio of untwisting is 1.7–1.9, and the K value is 0.7–0.8; the D / Y ratio of reverse-twisting is 1.4–1.6, and the K value is 0.5–0.65. The preparation method provided by this invention can realize the untwisting process of single-strand filaments, effectively reducing processing costs.

Description

Technical Field

[0001] This invention relates to the field of textile technology, and in particular to a single-strand non-twisted yarn and its preparation method. Background Technology

[0002] Traditional single-strand texturing yarns are either S-shaped or Z-shaped, resulting in residual torque. During subsequent weaving processes, the yarn twists and knots, easily causing machine shutdowns. Furthermore, the woven fabric tends to twist, failing to maintain flatness and affecting its appearance. While using a dual-track machine avoids these problems—for example, by combining two yarns, one Z-twist and the other S-twist, with the twists canceling each other out (as disclosed in Chinese patent CN111647993A for a production process of untwisted low-elasticity yarn)—this approach increases costs. For instance, when the finished product specification is 75D / 72F, 37.5D / 36F raw yarn is required, necessitating custom orders. Although this avoids weaving anomalies, it makes sourcing raw materials difficult, leading to longer lead times, higher costs, and difficulties in texturing operations.

[0003] Existing technologies can also obtain untwisted yarn by sizing the raw yarn and then untwisting and reverse twisting it, such as the method for manufacturing untwisted yarn disclosed in Chinese Patent CN1643197A. However, this method requires sizing the raw yarn, which also increases the preparation cost.

[0004] Chinese patent CN1330175A enables the untwisting of short fibers by adding an additional false twisting device to the ring spinning machine, but it cannot be applied to chemical fibers because it lacks a heating box function.

[0005] Chinese patent CN1804170B discloses a secondary processing technology for short fibers, which can realize the untwisting operation of short fibers, but it cannot be applied to the processing of chemical fibers. Summary of the Invention

[0006] In order to overcome the defects of the prior art, the technical problem to be solved by the present invention is to provide a preparation method that can realize the untwisting of a single strand of raw yarn, and a single strand of untwisted yarn prepared by the aforementioned preparation method.

[0007] To solve the above-mentioned technical problems, the present invention provides a method for preparing single-strand untwisted yarn, including the step of heating a single-strand raw yarn with a pre-twisted orientation to make it thermoplastic;

[0008] And the steps of untwisting and reverse twisting the thermoplastic single strand of raw yarn in sequence;

[0009] Wherein, the direction of untwisting is opposite to the direction of pre-twisting, and the direction of reverse twisting is the same as the direction of pre-twisting;

[0010] The D / Y ratio of the untwisted material is 1.7 to 1.9, and the K value is 0.7 to 0.8.

[0011] The reverse twisting process has a D / Y ratio of 1.4 to 1.6 and a K value of 0.5 to 0.65.

[0012] Furthermore, a single strand of untwisted yarn prepared by the aforementioned preparation method is provided, wherein the surface of the single strand of untwisted yarn has no obvious twist.

[0013] The beneficial effects of this invention are as follows: the detwisting of a single strand of raw yarn is achieved through the processes of untwisting and reverse twisting. Specifically, the untwisted single strand of raw yarn is reverse twisted with a lower D / Y ratio and a higher K value. This avoids the formation of fuzz in the reverse-twisted single strand while ensuring it has a specific twist direction, such as an S-twist. This prevents the processing allowance from causing the single strand to retain a Z-twist, thus obtaining a single strand of raw yarn in an untwisted state. Attached Figure Description

[0014] Figure 1 The diagram shown is a conventional installation diagram of the upper false twister and the lower false twister in a specific embodiment of the present invention;

[0015] Figure 2 The diagram shown is an installation schematic of the modified upper and lower false twisters in a specific embodiment of the present invention.

[0016] Figure 3 The diagram shown is a structural schematic of the upper false twister and the lower false twister in a specific embodiment of the present invention;

[0017] Labeling explanation: 1. Upper false twister; 2. Lower false twister; 3. Single strand of raw yarn; 4. Guide ceramic component; 5. False twist disc. Detailed Implementation

[0018] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0019] A method for preparing single-strand untwisted yarn includes a step of heating a pre-twisted single-strand filament to make it thermoplastic; and a step of sequentially untwisting and reverse-twisting the thermoplastic single-strand filament; wherein the direction of untwisting is opposite to the pre-twisting direction, and the direction of reverse-twisting is the same as the pre-twisting direction; the D / Y ratio of untwisting is 1.7 to 1.9, and the K value is 0.7 to 0.8; the D / Y ratio of reverse-twisting is 1.4 to 1.6, and the K value is 0.5 to 0.65.

[0020] In this document, the single-strand filament is a synthetic fiber filament. Both untwisting and reverse twisting are performed using a false twister. In one optional embodiment, an upper false twister (Z-twist) for untwisting and a lower false twister (S-twist) for reverse twisting are included. When the single-strand filament (S-twist) passes sequentially through the upper and lower false twisters, the upper false twister untwises the filament in the reverse direction, forming a conventional Z-direction DTY (Draw Texturing Yarn). The lower false twister then reverse twists the filament to a slightly S-twist (twist of approximately 10-15 twists / m), thus applying mechanical force in the reverse direction to achieve a twist-free effect. In this embodiment, the lower false twister forms a twist direction on the single-strand filament that is the same as its pre-twist direction, preventing the processing allowance from causing the filament to remain biased towards its untwisting direction. Therefore, in this embodiment, one-step forming from raw material POY can be achieved.

[0021] However, the installation direction of the guide ceramic parts 4 of the conventional upper false twister 1 and lower false twister 2 is fixed, that is, the installation direction of the guide ceramic parts 4 of the upper false twister 1 and lower false twister 2 is the same (i.e., forward installation), as shown below. Figure 1 As shown in the diagram (the arrows define the rotation direction of the false twisting disc 5, and the dotted lines indicate the position of the single-strand raw yarn 3 after it falls off), under this installation method, the single-strand raw yarn 3 is easily dislodged from one of the guide ceramic parts 4 by the action of the twisting disc, making the false twisting process difficult. Therefore, it is preferable to change the installation direction of the upper false twister 1 and the lower false twister 2, preferably by reversing their installation, that is, one guide ceramic part 4 is installed upright and the other is installed in reverse, such as... Figure 2 As shown (the arrows in the figure define the rotation direction of the false twisting disc 5), in this embodiment, the single strand of raw yarn 3 is fixed to the upper false twister 1 and the lower false twister 2 by the constraint of the guide ceramic component 4, thereby avoiding the aforementioned problem. More preferably, the upper false twister 1 and the lower false twister 2 are arranged in a staggered manner, such as... Figure 3 As shown, this is to improve the aforementioned constraint effect.

[0022] In this embodiment, the purpose of heating is to impart thermoplasticity to the single-strand filament, thereby facilitating subsequent untwisting and reverse twisting processes. Heating is preferably performed using a heating box with a temperature of 175–195°C and a machine speed of 600–650 m / min. However, when using an existing heating box (such as model KF6-1000), the single-strand filament cools down too quickly, becoming unplastic by the time it passes the lower false twister. Therefore, it is preferable to modify the heating box by removing its cooling plate to indirectly extend the cooling time. Specifically, since the melting temperature of polyester filament is around 255–260°C, its glass transition temperature is approximately 70°C, and its softening point is approximately 230°C, and the overall length of the heating box is 2.0 m, when the temperature of the heating box is limited to 175–195°C, the single-strand filament is heated in the heating box for approximately 0.3 seconds. At this point, by reducing the vehicle speed and removing the cooling plate, the cooling time of the single strand of raw filament is effectively extended, ensuring the rigidity of the single strand of raw filament on the upper and lower false twisters.

[0023] In an optional embodiment, the preparation method further includes a step of bundling the untwisted single-strand filaments, and a heat-setting step of the bundled single-strand filaments. Bundling is a general definition in the art, where compressed air, such as through a nozzle, is sprayed onto the filaments, causing multiple filaments to intertwine and interweave into a single strand within the nozzle space. This enhances the filaments' strength, abrasion resistance, and production efficiency, while preventing fuzz formation. Finally, the heat-setting step sets the untwisted single-strand untwisted yarn to ensure its untwisted effect.

[0024] In one optional embodiment, with a vehicle speed of 600 m / min, the heat setting temperature is 165–178 °C.

[0025] The single-strand untwisted yarn prepared by the aforementioned preparation method has no obvious twist on its surface, a fineness of 84–169 dtex, a strength of 3.8–3.92 cN / dtex, and an elongation of 18.5%–20.5%.

[0026] Example 1

[0027] A method for preparing single-strand untwisted yarn, wherein the single-strand raw material is polyester POY (specification: 270 / 48; batch number: 8P1052197R; 40kg) prepared according to the parameters shown in Table 1:

[0028] Table 1

[0029]

[0030]

[0031] The physical properties of the single-strand non-twisted yarn prepared by this method were tested and found to be: fineness: 169 dtex; strength: 3.8 cN / dtex; elongation: 19%, which meets the requirements for subsequent weaving.

[0032] After external inspection and dyeing assessment, the batch of finished products was found to have a 98% pass rate, and the residual torque of the yarn met the planned production requirements. The pass rate was primarily based on visual inspection, with no obvious fuzz, a soft and uniform texture, physical properties meeting national standards, a dyeing rating of 4.0 or higher, and no obvious twist on the fabric surface.

[0033] Example 2

[0034] A method for preparing single-strand non-twisted yarn, wherein the single-strand raw material is polyester POY (specification: 270 / 72; batch number: 8P0551214R; 60kg) prepared according to the parameters shown in Table 2:

[0035] Table 2

[0036] Project Name parameter YS (processing speed) 600m / min DR (draw ratio) 1.74 W6.1 (with upper false twister, Z twist) 1.9 (D / Y), 0.7 (K value) W6 (lower false twister, S-twist) 1.4 (D / Y), 0.5 (K value) H1 (Heating Box) 190℃ (heating temperature), approximately 350m / min (vehicle speed) H2 (Shaping Heat Box) 165℃ (heating temperature), approximately 560m / min (vehicle speed) Nozzle (Model: P243) 1.4mm (aperture), 1.3kg (air pressure) W2X (Assistant Lola) Overfeed -3.3％ W3 (Three Rolla) Overfeed -4％ W4 (Four-Lola) Overfeed -5.2％ Roll-up procedure (107) 29 degrees The winding head rotates approximately 320 times per minute at an angle of 29°.

[0037] The physical properties of the single-strand non-twisted yarn prepared by this method were tested and found to be: fineness: 167 dtex; strength: 3.92 cN / dtex; elongation: 18.5%, which meets the requirements for subsequent weaving.

[0038] After external inspection and dyeing assessment, the pass rate of this batch of finished products was 97.6%, and the residual torque of the yarn met the planned production requirements.

[0039] Example 3

[0040] A method for preparing single-strand untwisted yarn, wherein the single-strand raw material is polyester POY (specification: 140 / 72; batch number: 8P0131759R; 60kg) prepared according to the parameters shown in Table 3:

[0041] Table 3

[0042] Project Name parameter YS (processing speed) 600m / min DR (draw ratio) 1.77 W6.1 (with upper false twister, Z twist) 1.95 (D / Y), 0.8 (K value) W6 (lower false twister, S-twist) 1.52 (D / Y), 0.65 (K value) H1 (Heating Box) 178℃ (heating temperature), approximately 350m / min (vehicle speed) H2 (Shaping Heat Box) 165℃ (heating temperature), approximately 560m / min (vehicle speed) Nozzle (Model: P243) 1.4mm (aperture), 1.3kg (air pressure) W2X (Assistant Lola) Overfeed -3.5％ W3 (Three Rolla) Overfeed -4.2％ W4 (Four-Lola) Overfeed -5.2％ Roll-up procedure (107) 29 degrees The winding head rotates approximately 320 times per minute at an angle of 29°.

[0043] The physical properties of the single-strand non-twisted yarn prepared by this method were tested and found to be: fineness: 84 dtex; strength: 3.82 cN / dtex; elongation: 20.5%, which meets the requirements for subsequent weaving.

[0044] After external inspection and dyeing assessment, the pass rate of this batch of finished products was 98.2%, and the residual torque of the yarn met the planned production requirements.

[0045] In summary, this invention increases the temperature of the upper heating box, allowing the polyester filament to absorb more heat within the box. Removing the cooling plate allows the filament to maintain its proper thermoplasticity. When the filament passes through the upper false twister, a K value of 0.7–0.8 is set, which functions as a conventional Z-direction false twist. Then, while maintaining thermoplasticity, the filament enters the lower false twister. The lower false twister maintains a low D / Y ratio and a low K value (0.5–0.65) to avoid fuzz formation, thus twisting the Z-direction and achieving a slight S-direction bias. Afterward, heat setting is performed to keep the yarn in an untwisted state.

[0046] Compared with existing yarns, the single-strand non-twisted yarn obtained by the preparation method provided by the present invention can significantly reduce twist to zero while ensuring the pass rate of physical indicators and dyeing results. The fabric surface can remain flat compared with existing yarn technology, and there will be no slant due to yarn. The raw materials are easy to purchase and the operation is simple and convenient.

[0047] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing single-strand non-twisted yarn, characterized in that, This includes the step of heating a pre-twisted monofilament to make it thermoplastic; And the steps of untwisting and reverse twisting the thermoplastic single strand of raw yarn in sequence; Wherein, the direction of untwisting is opposite to the direction of pre-twisting, and the direction of reverse twisting is the same as the direction of pre-twisting; The D / Y ratio of the untwisted material is 1.7 to 1.9, and the K value is 0.7 to 0.

8. The reverse twisting has a D / Y ratio of 1.4 to 1.6 and a K value of 0.5 to 0.

65.

2. The preparation method according to claim 1, characterized in that, The heating temperature is 175–195°C.

3. The preparation method according to claim 1, characterized in that, The single strand of raw yarn after reverse twisting has the same twist direction as the pre-twisted direction, and its twist is 10-15 twists / m.

4. The preparation method according to claim 1, characterized in that, The direction of untwisting is Z-twisting, and the direction of reverse twisting is S-twisting.

5. The preparation method according to claim 1, characterized in that, It also includes the steps of bundling the reverse-twisted single strands of raw yarn and heat-setting the bundled single strands of raw yarn.

6. The preparation method according to claim 5, characterized in that, The heat setting temperature is 165°C.

7. A single-strand non-twisted yarn prepared by the preparation method according to any one of claims 1 to 6, characterized in that, The surface of the single strand of untwisted yarn has no obvious twist.

8. The single-strand non-twisted yarn according to claim 7, characterized in that, The fineness of the single strand of untwisted yarn is 84–169 dtex.

9. The single-strand non-twisted yarn according to claim 7, characterized in that, The strength of the single strand of untwisted yarn is 3.8–3.92 cN / dtex.

10. The single-strand non-twisted yarn according to claim 7, characterized in that, The elongation of the single strand of untwisted yarn is 18.5% to 20.5%.

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