A low tension production process for super-soft, weak twist spun yarn

Abstract

The application provides a low-tension production process of super-soft weak-twist short fiber yarn, which is realized through raw material fine pretreatment, short fiber-long filament embedded composite feeding, three roller precise drafting, multiple gathering and hot and wet softening cooperation, low-tension twisting and winding and optional fancy control or post-processing. The short fiber is subjected to opening, carding and three-parallel-drawing optimization treatment, and the long filament is subjected to precise pre-tension control; the composite feeding adopts specific spacing and guide filament parameters, and the drafting system is matched with low-tension parameters; multiple gathering is combined with hot and wet softening to improve the fiber cohesion, and the twisting and winding controls the low tension and the forming, so that the pain points of weak twist yarn, such as insufficient strength and too much hairiness, are solved, the super-soft hand feeling, low hairiness and high uniformity are combined, and the application is suitable for high-end knitting and close-fitting textiles.

Description

Technical Field

[0001] This invention relates to the field of textile spinning technology, and more specifically, to a low-tension production process for ultra-soft, low-twist staple fiber yarn. Background Technology

[0002] Ultra-soft, low-twist staple fiber yarns possess excellent softness, skin-friendliness, and breathability, making them widely used in high-end knitwear, infant and toddler clothing, and home textiles. However, in traditional staple fiber spinning processes, a high twist is often required to ensure yarn strength, resulting in a stiffer hand feel that fails to meet the ultra-softness requirement. Simultaneously, the short fiber slivers experience significant tension during spinning, making them prone to breakage. This is especially problematic when producing high-count or ultra-high-count yarns or using low-grade raw materials or waste short fibers, leading to poor spinning stability and low fiber utilization, thus hindering the efficient production of ultra-soft, low-twist staple fiber yarns.

[0003] Among existing spinning technologies, novel spinning techniques such as Siro compact spinning, embedded composite spinning, soft and clean spinning, and multi-compact spinning provide feasible approaches to improve yarn performance and reduce spinning tension. Specifically, Siro compact spinning uses negative pressure to compactly gather fiber slivers, reducing hairiness; embedded composite spinning utilizes the protection and tension sharing of short fiber slivers by filaments, enabling normal spinning with a small number of fiber ends, significantly reducing breakage rates and facilitating the development of ultra-high count yarns; soft and clean spinning reduces yarn hairiness and internal stress through hot and wet softening treatment; and multi-compact spinning further optimizes yarn surface smoothness and overall performance through layered and multi-layered control of yarn structure. Furthermore, nylon filaments, due to their lightweight, high strength, excellent resilience, and abrasion resistance, can be blended with short fibers to improve fabric performance, but the application of combining short fibers such as lyocell with nylon filaments in spinning is currently limited; the production technology of composite yarns such as AB-type fancy yarns provides direction for the functionalization and differentiation development of ultra-soft, low-twist yarns.

[0004] However, existing spinning technologies alone cannot simultaneously meet the production requirements of low tension, low hairiness, high stability, and high fiber utilization for ultra-soft, low-twist staple fiber yarns. Therefore, a low-tension production process for ultra-soft, low-twist staple fiber yarns is proposed. Summary of the Invention

[0005] The purpose of this invention is to address the problems raised in the existing background technology. To achieve the above-mentioned objective, this invention provides the following technical solution: a low-tension production process for ultra-soft, low-twist staple fiber yarn, comprising the following steps: raw material selection and refined pretreatment, composite feeding and precise drafting, multiple aggregation and heat and moisture softening synergistic treatment, low-tension twisting and stable winding, fancy structure control and finished product post-treatment; In the selection of raw materials, the short fiber raw materials are selected from one or more of Lyocell, pure cotton (combed), Modal, and wool fiber, and the long filament raw materials are selected from one or more of polyester, nylon, spandex, and polypropylene. The refined pretreatment includes staple fiber pretreatment and filament pretreatment; wherein the staple fiber pretreatment needs to be matched with the corresponding process according to the spinning process path: If ring spinning, compact spinning, or Siro spinning is subsequently adopted, then the opening and cleaning, carding, three-stage drawing, and roving process must be used. If the subsequent spinning process is rotor spinning, air jet spinning, or friction spinning, then the opening and cleaning, carding, and three-stage drawing process can be used; the pretension of the filament pretreatment is adjusted by a tension controller.

[0006] As a preferred technical solution of the present invention, the short fiber pretreatment specifically includes: In the cotton opening and cleaning process, the speed of the cotton cleaning beater is 800-950 r / min, the cotton flow velocity is 0.8-1.2 m / s, and the distance between the beater and the dust bar is 8-12 mm. In the carding process, the cylinder speed is 320-360 r / min, the flats speed is 80-120 mm / min, the cylinder-flats distance is 0.25-0.30 mm, and the sliver weight is 18-22 g / 5m. In the final drawing process, the basis weight is 12-15g / 5m, the front-middle gap of the rollers is 22-25mm, the middle-back gap is 22-28mm, the total draft ratio is 4-6 times, the back zone draft ratio is 1.1-1.3 times, and the sliver exit speed is 220-250m / min; the evenness CV value of the treated short fiber roving is ≤2.5%, and the weight unevenness is ≤1.0%.

[0007] As a preferred technical solution of the present invention, the pretension of the filament pretreatment is adjusted by a magnetic damping tension controller.

[0008] As a preferred technical solution of the present invention, the composite feeding adopts a short fiber-long filament embedded cooperative structure: Two short fiber rovings are fed in parallel through a double-hole flared mouth with a diameter of 3.0-4.0mm and a spacing of 3-5mm. The distance from the flared mouth outlet to the rear roller clamp is 15-20mm. The filament is fed into the short fiber roving sliver 0.8-1.2mm outside through a ceramic guide hook with a diameter of 0.8-1.0mm. The guide hook is 8-12mm from the back roller nip and the guide angle is 30-45°, which is the angle between the guide hook and the direction of sliver travel.

[0009] As a preferred technical solution of the present invention, the precise drafting adopts a three-roller double-rubber ring drafting device: Front roller diameter 25-28mm, output speed 14–20 m / min; middle roller diameter 27-30mm; rear roller diameter 27-30mm. The thickness of the rubber ring is 0.8-1.0mm, and the gap between the rubber ring jaws is 2.0-2.5mm.

[0010] As a preferred technical solution of the present invention, the synergistic treatment of multiple aggregation and thermal and moisture flexibility specifically includes: First, multiple aggregation is carried out using a 2-3 series trough aggregation device. The width of the first aggregation trough is 2.0-2.5mm, the width of the second aggregation trough is 1.5-2.0mm, the width of the third aggregation trough is 1.0-1.5mm, and the depth of the aggregation trough is 1.5-2.0mm. The residence time of the sliver in the trough is 0.1-0.2s, and the negative pressure fluctuation is ≤±20Pa. Then, a hot and humid softening treatment is carried out using a steam spray hot and humidification device. The treatment temperature is 40-60℃, the relative humidity is 60%-80%, the steam pressure is 0.1-0.15MPa, and the hot and humidification treatment time is 0.5-1.0s. After the treatment, the moisture content of the exposed loose fibers is 8%-12%, and the fiber breaking elongation is increased by 5%-10%.

[0011] As a preferred technical solution of the present invention, the low-tension twisting and stable winding specifically refers to: The twisting process uses a low-inertia spindle with a spindle speed of 8000-12000 r / min and a twist of 300-600 twists / meter (S-twist or Z-twist). The twist deviation is ≤ ±5 twists / meter. The winding process is monitored online using an electronic yarn clearer. The winding speed is 800-1000 m / min, the winding tension is 2-5 cN, and the tension fluctuation is ≤±0.8 cN. The ring diameter is 42-51 mm, the traveler weight is 0.8-1.5 gauge, the yarn package is formed into a conical pagoda shape, the yarn package weight is 1.5-2.0 kg, and the yarn winding density is 0.45-0.55 g / cm³. 3 .

[0012] As a preferred technical solution of the present invention, the fancy structure adjustment specifically includes: When producing AB type yarn, the color difference ΔE of the two short fiber rovings is ≥3, and the difference in draft ratio is 0.5-1.0 times. The feeding ratio of the short fiber rovings is controlled by the program. The length of the two-color section is 5-20mm, and the section length deviation is ≤±1.0mm. When producing slub AB yarn, the slub effect is achieved by abruptly changing the draft ratio. The slub length is 5-30mm, the slub thickness is 1.5-3.0 times that of the base yarn, the slub spacing is 50-200mm, and the slub shape is a gradient at both ends.

[0013] As a preferred technical solution of the present invention, the post-processing of the finished product specifically includes: The process employs a loose-air hot air setting method, with a setting temperature of 80-100℃, a setting time of 20-30 minutes, and a hot air velocity of 0.5-1.0 m / s. The moisture regain of the yarn after setting is 8%-10%, and the heat shrinkage rate is ≤2.0%. The properties of the finished yarn are as follows: evenness CV value ≤14%, number of hairs larger than 3mm ≤5 hairs / m, a reduction of ≥49% compared to traditional ring spinning, breaking strength ≥2.5cN / dtex, and softness score ≥4.5 points.

[0014] As a preferred technical solution of the present invention, the post-processing of the finished product adopts a loose setting process, with the following specific parameters: setting temperature of 80–100℃, setting time of 20–30 min; and yarn moisture regain controlled at 8%–10% after setting.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: Low-tension spinning is stable and reliable: The embedded composite spinning filament feeding mode can effectively share the tension borne by the short fiber sliver. Even if there are only 10 fibers in the cross section of the short fiber sliver, it can still be spun normally. The utilization rate of low-grade raw materials and waste short fibers is increased by more than 20%, and the raw material cost is reduced by 15%-25%.

[0016] The yarn boasts superior ultra-soft performance: through low-twist design combined with the softening and heat-wet treatment, the yarn breaking elongation is increased by 15%-25%, the hand softness score is ≥4.5 points, and the number of hairs larger than 3mm is reduced by 49%-93.5% compared to traditional ring spinning, meeting the ultra-soft and skin-friendly requirements of high-end textiles.

[0017] Excellent overall yarn performance: Multiple aggregation processes make the yarn structure compact, with a yarn evenness CV value ≤14% and a strength and elongation that are more than 30% higher than traditional low-twist yarns; excellent air and moisture permeability, with moisture permeability, anti-pilling and anti-fuzzing grades reaching 3-4, and dyeing evenness ≥4.

[0018] With a wide range of applicable raw materials and diversified products, it can be adapted to various combinations of short fiber and filament raw materials to achieve efficient blending of lyocell and nylon filament; it can produce a variety of products such as conventional super soft yarn, AB type fancy yarn, and slub AB yarn, which are suitable for multiple scenarios such as infant and toddler clothing, home decoration, and high-end women's wear, and have strong market adaptability. Attached Figure Description

[0019] Figure 1 This is a comparison diagram of the hairiness of the soft yarn of this invention and ordinary ring-spun yarn; Figure 2 These are scanning electron microscope images of the ring-spun, multi-compacted, and ordinary compacted yarns of this invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention.

[0021] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely illustrates some embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features and technical solutions in the embodiments of the present invention can be combined with each other. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] Example 1: A low-tension production process for ultra-soft, low-twist staple fiber yarn, comprising the following steps: raw material selection and refined pretreatment, composite feeding and precise drafting, multiple aggregation and heat and moisture softening synergistic treatment, low-tension twisting and stable winding, fancy structure control and finished product post-treatment; In the selection of raw materials, the short fiber raw materials are selected from one or more of Lyocell, pure cotton (combed), Modal, and wool fiber, and the long filament raw materials are selected from one or more of polyester, nylon, spandex, and polypropylene. Refined pretreatment includes staple fiber pretreatment and filament pretreatment; among which, staple fiber pretreatment needs to match the corresponding process according to the spinning process path: If ring spinning, compact spinning, or Siro spinning is subsequently adopted, then the opening and cleaning, carding, three-stage drawing, and roving process must be used. If the subsequent spinning process is rotor spinning, air jet spinning, or friction spinning, then the opening and cleaning, carding, and three-stage drawing process can be used; the pretension of the filament pretreatment is adjusted by a tension controller.

[0023] The specific pretreatment of short fibers is as follows: In the cotton opening and cleaning process, the speed of the cotton cleaning beater is 800-950 r / min, the cotton flow velocity is 0.8-1.2 m / s, and the distance between the beater and the dust bar is 8-12 mm. In the carding process, the cylinder speed is 320-360 r / min, the flats speed is 80-120 mm / min, the cylinder-flats distance is 0.25-0.30 mm, and the sliver weight is 18-22 g / 5m. In the final drawing process, the basis weight is 12-15g / 5m, the front-middle gap of the rollers is 22-25mm, the middle-back gap is 22-28mm, the total draft ratio is 4-6 times, the back zone draft ratio is 1.1-1.3 times, and the sliver exit speed is 220-250m / min; the evenness CV value of the treated short fiber roving is ≤2.5%, and the weight unevenness is ≤1.0%.

[0024] The pretension of the filament pretreatment is adjusted by a magnetic damping tension controller.

[0025] The composite feeding adopts a short fiber-long filament embedded synergistic structure: Two short fiber rovings are fed in parallel through a double-hole flared mouth with a diameter of 3.0-4.0mm and a spacing of 3-5mm. The distance from the flared mouth outlet to the rear roller clamp is 15-20mm. The filament is fed into the short fiber roving sliver 0.8-1.2mm outside through a ceramic guide hook with a diameter of 0.8-1.0mm. The guide hook is 8-12mm from the back roller nip and the guide angle is 30-45°, which is the angle between the guide hook and the direction of sliver travel.

[0026] Precision drafting employs a three-roller, double-rubber-ring drafting device: Front roller diameter 25-28mm, output speed 14–20 m / min; middle roller diameter 27-30mm; rear roller diameter 27-30mm. The thickness of the rubber ring is 0.8-1.0mm, and the gap between the rubber ring jaws is 2.0-2.5mm.

[0027] The specific details of the synergistic treatment of multiple aggregations and thermal and moisture flexibility are as follows: First, multiple aggregation is carried out using a 2-3 series trough aggregation device. The width of the first aggregation trough is 2.0-2.5mm, the width of the second aggregation trough is 1.5-2.0mm, the width of the third aggregation trough is 1.0-1.5mm, and the depth of the aggregation trough is 1.5-2.0mm. The residence time of the sliver in the trough is 0.1-0.2s, and the negative pressure fluctuation is ≤±20Pa. Then, a hot and humid softening treatment is carried out using a steam spray hot and humidification device. The treatment temperature is 40-60℃, the relative humidity is 60%-80%, the steam pressure is 0.1-0.15MPa, and the hot and humidification treatment time is 0.5-1.0s. After the treatment, the moisture content of the exposed loose fibers is 8%-12%, and the fiber breaking elongation is increased by 5%-10%.

[0028] Low-tension twisting and stable winding specifically refer to: The twisting process uses a low-inertia spindle with a spindle speed of 8000-12000 r / min and a twist of 300-600 twists / meter (S-twist or Z-twist). The twist deviation is ≤ ±5 twists / meter. The winding process is monitored online using an electronic yarn clearer. The winding speed is 800-1000 m / min, the winding tension is 2-5 cN, and the tension fluctuation is ≤±0.8 cN. The ring diameter is 42-51 mm, the traveler weight is 0.8-1.5 gauge, the yarn package is formed into a conical pagoda shape, the yarn package weight is 1.5-2.0 kg, and the yarn winding density is 0.45-0.55 g / cm³. 3 .

[0029] The specific adjustments to the fancy structure are as follows: When producing AB type yarn, the color difference ΔE of the two short fiber rovings is ≥3, and the difference in draft ratio is 0.5-1.0 times. The feeding ratio of the short fiber rovings is controlled by the program. The length of the two-color section is 5-20mm, and the section length deviation is ≤±1.0mm. When producing slub AB yarn, the slub effect is achieved by abruptly changing the draft ratio. The slub length is 5-30mm, the slub thickness is 1.5-3.0 times that of the base yarn, the slub spacing is 50-200mm, and the slub shape is a gradient at both ends.

[0030] The specific post-processing of the finished product is as follows: The process employs a loose-air hot air setting method, with a setting temperature of 80-100℃, a setting time of 20-30 minutes, and a hot air velocity of 0.5-1.0 m / s. The moisture regain of the yarn after setting is 8%-10%, and the heat shrinkage rate is ≤2.0%. The properties of the finished yarn are as follows: evenness CV value ≤14%, number of hairs larger than 3mm ≤5 hairs / m, a reduction of ≥49% compared to traditional ring spinning, breaking strength ≥2.5cN / dtex, and softness score ≥4.5 points.

[0031] The finished product is finished using a loose setting process with the following parameters: setting temperature of 80–100℃ and setting time of 20–30 min; the yarn moisture regain after setting is controlled at 8%–10%.

[0032] Example 2: Low-tension production process of ultra-soft, weakly twisted staple fiber yarn I. Raw material screening and pretreatment Raw material selection: Based on the yarn performance positioning, one or more of Lyocell, combed pure cotton, Modal, and wool fibers are selected as short fiber raw materials; one or more of polyester, nylon, spandex, and polypropylene are selected and combined as filament raw materials.

[0033] Refined preprocessing Short fiber pretreatment: Match the corresponding process according to the subsequent spinning process. If ring spinning, compact spinning or Siro spinning is used, complete the opening and cleaning, carding, multiple drawing and roving processes in sequence; if rotor spinning, air-jet spinning or friction spinning or other free-end spinning processes are used, complete the opening and cleaning, carding and multiple drawing processes.

[0034] Filament pretreatment: The filament feeding tension is adjusted by a tension controller to ensure stable and consistent tension.

[0035] II. Compound feeding and stretching Composite feeding: The short fiber and long filament are embedded and fed in a coordinated manner. The short fiber roving is arranged in parallel and fed in synchronously, maintaining a fixed spacing. The long filament is placed at a preset position outside the short fiber sliver. The guide angle and feeding distance are precisely controlled to ensure stable matching of the feeding positions of the short fiber and long filament.

[0036] Precise drawing: Relying on a special drawing device, the fed fiber sliver is drawn according to a preset drawing ratio to ensure synchronous fiber movement and achieve uniform and controllable sliver thickness.

[0037] III. Aggregated Compliance Collaborative Processing Multiple aggregation: The drawn slivers are passed through multiple aggregation grooves with decreasing width gradients in sequence. The loose fibers are gathered together by the negative pressure adsorption, which reduces the width of the slivers and optimizes the fiber arrangement.

[0038] Hot and humid softening treatment: Applying a hot and humid environment to the aggregated slivers, using steam to improve the surface friction characteristics of the fibers, reduce the rigid resistance between fibers, and make the fibers more supple and flexible as a whole.

[0039] IV. Low-tension twisting and winding Low-tension twisting: Using a low-inertia twisting component, the fiber sliver is twisted while maintaining a low-tension state. By adjusting the twisting speed and twisting direction, the yarn twist is kept stable and the twisting is uniform.

[0040] Stable winding: Equipped with an online monitoring device, the yarn condition is monitored in real time, and the winding tension is dynamically adjusted. With the appropriate winding components, the yarn package is formed in a regular manner, and sudden changes in yarn tension are avoided during the winding process.

[0041] V. Fancy Structure Adjustment Select the corresponding process path based on product design requirements: AB type yarn control: Select two types of short fiber rovings with color differences, set differentiated draft ratios, and control the feeding rhythm of the two fibers through a program to form a regular two-color segmented structure.

[0042] Bamboo joint AB yarn control: By abruptly changing the stretch ratio, the slivers are locally thickened, controlling the length, thickness, and distribution spacing of the bamboo joints to form a gradual bamboo joint shape with a natural transition at both ends.

[0043] VI. Post-processing of finished products The wound yarn is then subjected to loose hot air setting. The hot air eliminates residual tension within the yarn, stabilizes the yarn structure and twist, controls the yarn moisture regain, and further optimizes the yarn's softness and dimensional stability, ultimately yielding the finished yarn. The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described herein. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the specific embodiments described above. Therefore, any modifications or equivalent substitutions to the present invention, as well as all technical solutions and improvements that do not depart from the spirit and scope of the invention, are covered within the scope of the claims of the present invention.

Claims

1. A low-tension production process for ultra-soft, low-twist staple fiber yarn, characterized in that, Includes the following steps: Raw material selection and fine pretreatment, compound feeding and precise stretching, multiple aggregation and hot and wet softening synergistic treatment, low tension twisting and stable winding, to carry out fancy structure control and finished product post-processing; In the selection of raw materials, the short fiber raw materials are selected from one or more of Lyocell, pure cotton (combed), Modal, and wool fiber, and the long filament raw materials are selected from one or more of polyester, nylon, spandex, and polypropylene. The refined pretreatment includes staple fiber pretreatment and filament pretreatment; wherein the staple fiber pretreatment needs to be matched with the corresponding process according to the spinning process path: If ring spinning, compact spinning, or Siro spinning is subsequently adopted, then the opening and cleaning, carding, three-stage drawing, and roving process must be used. If the subsequent spinning process is rotor spinning, air jet spinning, or friction spinning, then the opening and cleaning, carding, and three-stage drawing process can be used; the pretension of the filament pretreatment is adjusted by a tension controller.

2. The low-tension production process for ultra-soft, weak-twist staple fiber yarn according to claim 1, characterized in that, The pretreatment of the short fibers specifically includes: In the cotton opening and cleaning process, the speed of the cotton cleaning beater is 800-950 r / min, the cotton flow velocity is 0.8-1.2 m / s, and the distance between the beater and the dust bar is 8-12 mm. In the carding process, the cylinder speed is 320-360 r / min, the flats speed is 80-120 mm / min, the cylinder-flats distance is 0.25-0.30 mm, and the sliver weight is 18-22 g / 5m. In the final drawing process, the basis weight is 12-15g / 5m, the front-middle gap of the rollers is 22-25mm, the middle-back gap is 22-28mm, the total draft ratio is 4-6 times, the back zone draft ratio is 1.1-1.3 times, and the sliver exit speed is 220-250m / min; the evenness CV value of the treated short fiber roving is ≤2.5%, and the weight unevenness is ≤1.0%.

3. The low-tension production process for ultra-soft, weakly twisted staple fiber yarn according to claim 1, characterized in that, The filament pretreatment is performed by adjusting the pretension using a magnetic damping tension controller.

4. The low-tension production process for ultra-soft, weak-twist staple fiber yarn according to claim 1, characterized in that, The composite feeding adopts a short fiber-long filament embedded collaborative structure: Two short fiber rovings are fed in parallel through a double-hole flared mouth with a diameter of 3.0-4.0mm and a spacing of 3-5mm. The distance from the flared mouth outlet to the rear roller clamp is 15-20mm. The filament is fed into the short fiber roving sliver 0.8-1.2mm outside through a ceramic guide hook with a diameter of 0.8-1.0mm. The guide hook is 8-12mm from the back roller nip and the guide angle is 30-45°, which is the angle between the guide hook and the direction of sliver travel.

5. The low-tension production process for ultra-soft, weak-twist staple fiber yarn according to claim 1, characterized in that, The precise drafting process employs a three-roller, double-rubber-ring drafting device. Front roller diameter 25-28mm, output speed 14–20 m / min; middle roller diameter 27-30mm; rear roller diameter 27-30mm. The thickness of the rubber ring is 0.8-1.0mm, and the gap between the rubber ring jaws is 2.0-2.5mm.

6. The low-tension production process for ultra-soft, weak-twist staple fiber yarn according to claim 1, characterized in that, The specific details of the synergistic treatment of multiple aggregation and thermal-moisture flexibility are as follows: First, multiple aggregation is carried out using a 2-3 series trough aggregation device. The width of the first aggregation trough is 2.0-2.5mm, the width of the second aggregation trough is 1.5-2.0mm, the width of the third aggregation trough is 1.0-1.5mm, and the depth of the aggregation trough is 1.5-2.0mm. The residence time of the sliver in the trough is 0.1-0.2s, and the negative pressure fluctuation is ≤±20Pa. Then, a hot and humid softening treatment is carried out using a steam spray hot and humidification device. The treatment temperature is 40-60℃, the relative humidity is 60%-80%, the steam pressure is 0.1-0.15MPa, and the hot and humidification treatment time is 0.5-1.0s. After the treatment, the moisture content of the exposed loose fibers is 8%-12%, and the fiber breaking elongation is increased by 5%-10%.

7. The low-tension production process for ultra-soft, weak-twist staple fiber yarn according to claim 1, characterized in that, The low-tension twisting and stable winding specifically refers to: The twisting process uses a low-inertia spindle with a spindle speed of 8000-12000 r / min and a twist of 300-600 twists / meter (S-twist or Z-twist). The twist deviation is ≤ ±5 twists / meter. The winding process is monitored online using an electronic yarn clearer. The winding speed is 800-1000 m / min, the winding tension is 2-5 cN, and the tension fluctuation is ≤±0.8 cN. The ring diameter is 42-51 mm, the traveler weight is 0.8-1.5 gauge, the yarn package is formed into a conical pagoda shape, the yarn package weight is 1.5-2.0 kg, and the yarn winding density is 0.45-0.55 g / cm³. 3 .

8. The low-tension production process for ultra-soft, weakly twisted staple fiber yarn according to claim 1, characterized in that, The specific adjustment of the fancy structure is as follows: When producing AB type yarn, the color difference ΔE of the two short fiber rovings is ≥3, and the difference in draft ratio is 0.5-1.0 times. The feeding ratio of the short fiber rovings is controlled by the program. The length of the two-color section is 5-20mm, and the section length deviation is ≤±1.0mm. When producing slub AB yarn, the slub effect is achieved by abruptly changing the draft ratio. The slub length is 5-30mm, the slub thickness is 1.5-3.0 times that of the base yarn, the slub spacing is 50-200mm, and the slub shape is a gradient at both ends.

9. The low-tension production process for ultra-soft, weak-twist staple fiber yarn according to claim 1, characterized in that, The specific post-processing of the finished product is as follows: The process employs a loose-air hot air setting method, with a setting temperature of 80-100℃, a setting time of 20-30 minutes, and a hot air velocity of 0.5-1.0 m / s. The moisture regain of the yarn after setting is 8%-10%, and the heat shrinkage rate is ≤2.0%. The properties of the finished yarn are as follows: evenness CV value ≤14%, number of hairs larger than 3mm ≤5 hairs / m, a reduction of ≥49% compared to traditional ring spinning, breaking strength ≥2.5cN / dtex, and softness score ≥4.5 points.

10. The low-tension production process for ultra-soft, weakly twisted staple fiber yarn according to claim 9, characterized in that, The finished product post-treatment adopts a loose setting process with the following specific parameters: setting temperature is 80–100℃, setting time is 20–30 min; the yarn moisture regain after setting is controlled at 8%–10%.

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