Special-shaped cross-section fiber and preparation method thereof

Abstract

The invention relates to a special-shaped cross-section fiber and a preparation method thereof. The cross section of the special-shaped section fiber is provided with a reference structure distributed in a triangular mode, the cross section is provided with three corners, and each corner is provided with a pair of protrusions. The two bulges positioned at the same corner part are directly connected with each other to form a Y-shaped groove at the vertex of the corner part; every two adjacent protruding areas located at different corners are connected through continuous linear contours or curve contours, and the linear contours or the curve contours form three boundary contours of the triangular distribution reference structure. According to the special-shaped cross-section fiber, the conduction performance of liquid on the surface of the fiber is improved while the high glossiness is kept.

Description

Technical Field

[0001] This invention relates to the field of textile fiber preparation technology, and in particular to an irregular cross-section fiber and its preparation method. Background Technology

[0002] In existing technologies, due to limitations in spinning processes and forming structures, conventional synthetic fibers mostly adopt an approximately circular cross-sectional structure. While these fibers offer advantages in processing stability and production efficiency, they have limitations in luster and liquid conductivity, making it difficult to simultaneously achieve both good appearance and wearing comfort.

[0003] Natural silk products, due to their unique fiber cross-sectional structure, exhibit a distinct and soft luster in light reflection, while also possessing good wearing properties. However, the high cost and limited availability of silk raw materials make it difficult to meet the demands of large-scale applications. Therefore, developing synthetic fibers that combine aesthetic appeal with wearing comfort has become a focus of attention in this field. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an irregularly shaped cross-section fiber and its preparation method. By rationally designing the fiber's cross-sectional structure, the fiber's light reflection path and surface structure characteristics are optimized. This achieves a better gloss effect while also considering the liquid conductivity on the fiber surface, thereby improving the fiber's moisture absorption and wicking properties and enhancing its wearing comfort.

[0005] According to a first aspect of the invention, a shaped cross-section fiber is provided, wherein the fiber is formed of a polymer; the cross-section of the fiber has a reference structure distributed in a triangular pattern; the reference structure has three corners; a pair of protrusions are provided at each corner position; two protrusions located at the same corner position are directly connected to each other to form a Y-shaped groove at the vertex of the corner; two protrusion regions located at different corner positions and adjacent to each other are connected to each other by a continuous straight line profile or a curved profile; the straight line profile or curved profile constitutes the three boundary profiles of the triangularly distributed reference structure.

[0006] In some embodiments, a pair of protrusions located at the same corner position are symmetrically distributed about the angle bisector of the corner.

[0007] In some embodiments, a hollow cavity is formed inside the triangularly distributed reference structure; In some embodiments, the hollowness of the fiber is 1%-30%.

[0008] In some embodiments, the hollow cavity is triangular in the cross-section of the fiber.

[0009] In some embodiments, the circumcircle diameter of the reference structure Reduce incircle diameter With circumcircle diameter The ratio satisfies: 45% % The ratio of the distance OA from the centroid O of the cross section to the front end A of the protrusion to the distance OB from the centroid O to the bottom B of the Y-shaped groove, OA / OB is between 1.05 and 2. The width of the narrowest part of the main arm at the corner Maximum width of the Y-shaped groove at the end ratio Between 0.8 and 2.2; The included angle θ between the pair of protrusions forming the Y-shaped groove ranges from 30° to 120°. Monofilament fineness is 0.8-5.6 dtex.

[0010] According to a second aspect of the present invention, a method for preparing the above-mentioned irregular cross-section fiber is provided, comprising: step one: placing the fiber raw material in a dryer to complete pre-crystallization and drying treatment; step two: performing melt spinning on the obtained fiber raw material and extruding it through a spinneret to form nascent fiber; step three: after the nascent fiber is extruded from the spinneret, it enters a blowing cooling zone for cooling; and step four: obtaining the finished fiber after oiling, winding, and stretching.

[0011] In some embodiments, the cooling process in the air-blowing cooling area includes: a first air-blowing section and a second air-blowing section, wherein the second air-blowing section is located below the first air-blowing section, and the air pressure and air temperature of the second air-blowing section are both lower than those of the first air-blowing section.

[0012] In some embodiments, the first airflow is a circular airflow; the second airflow is a forward airflow.

[0013] According to a third aspect of the invention, a textile is provided that uses the irregularly shaped cross-section fibers described in any of the preceding claims.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects: 1. By introducing a triangularly distributed reference structure in the cross-section of the fiber and setting symmetrically distributed narrow protrusions at each corner, a multi-directional reflective interface is formed on the fiber surface, thereby controlling the reflection path of light on the fiber surface, making the distribution of reflected light more uniform, which is conducive to obtaining a brighter and softer gloss effect.

[0015] 2. The narrow protrusions in the fiber and the boundary contours formed by their interconnection constitute a continuous microstructure region on the fiber surface, which can form stable capillary channels on the fiber surface. This helps to enhance the capillary action and directional conduction of liquid on the fiber surface, thereby improving the moisture absorption and perspiration performance of the fiber.

[0016] 3. A multi-stage cooling process is used to cool the fibers in stages, thereby reducing the risk of cross-sectional collapse or shape distortion caused by uneven cooling. The high-temperature cooling air section (first stage) rapidly reduces the temperature of the nascent fibers and increases their viscosity, thus maintaining the irregular cross-sectional shape. At the same time, the high air temperature does not lower the temperature of the spinneret surface, preventing the fibers from becoming brittle due to drastic cooling. The co-current air section (second stage) further cools the fibers uniformly and isotropically, improving the structural integrity of the fibers and the reliability of subsequent processing. Attached Figure Description

[0017] Figure 1 This is a diagram illustrating the air blowing method; Figure 2 This is a schematic diagram of the cross-section of the irregular cross-section fiber of the present invention; Figure 3 This is a schematic diagram of the air-blowing cooling area of ​​the present invention; Figure 4 These are microscope images of Embodiment 1 of the present invention; Figure 5 These are microscope images of Embodiment 2 of the present invention; Figure 6 These are microscope images of Embodiment 3 of the present invention; Figure 7 This is a microscope photograph of Comparative Example 4 of the present invention; Figure 8 This is a microscope photograph of Comparative Example 7 of the present invention; Figure 9 This is a schematic diagram of dynamic contact angle test results for some embodiments and comparative examples of the present invention. Detailed Implementation

[0018] Embodiments of the invention will now be described more fully with reference to the accompanying drawings, in which embodiments of the invention are illustrated. However, the invention may be practiced in many different forms, and should not be construed as limited to the embodiments set forth herein.

[0019] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a” and “this” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that, when used herein, the term “comprising” specifies the presence of the stated features, integrals, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.

[0020] Unless otherwise defined, the terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Terms used herein shall be interpreted as having the same meaning as they have in the context of this specification and in the relevant field, and shall not be interpreted in an idealized or overly formal sense, unless specifically defined herein.

[0021] To achieve a luster similar to natural silk, current technologies typically prepare polymer fibers by mimicking the triangular cross-section structure of silk. However, in practical applications, simple triangular cross-section fibers still fall short of natural silk in terms of breathability, moisture permeability, and fabric bulkiness.

[0022] This invention provides a fiber structure with a special cross-sectional shape. Based on a triangular reference structure, two adjacent protrusions are provided at each corner position, and the two protrusions are connected to each other, thereby forming a Y-shaped groove in the corner region.

[0023] The formation of the Y-shaped grooves serves two purposes. First, it increases the multi-directional reflection paths of light on the fiber surface, thereby improving gloss. Second, the grooves create microchannel structures between the fibers, facilitating air circulation and moisture conduction, thus improving the fabric's breathability and moisture permeability. Furthermore, the raised structures increase the gaps between fibers, which, after the fabric is formed, increases the proportion of still air layers, thereby enhancing the fabric's thermal insulation performance.

[0024] In this invention, the overall profile of the fiber cross-section is described by a "reference structure". The reference structure is the basic profile framework that constitutes the geometry of the fiber cross-section, used to determine the spatial distribution relationship of the corner positions and protruding structures.

[0025] In this invention, the reference structure is triangularly distributed, including three corner regions that are evenly or approximately evenly spaced along the circumferential direction. This reference structure defines the main contour shape of the fiber cross-section and provides a positioning reference for the subsequent corner protrusion structures.

[0026] A pair of protruding structures are provided in each corner region, and the two protrusions are distributed symmetrically or approximately symmetrically along the corner.

[0027] This symmetrical arrangement allows the Y-shaped grooves to be evenly distributed circumferentially across the cross-section, thereby improving the uniformity of the airflow channel while ensuring structural balance.

[0028] To further improve thermal insulation performance, the fiber of this invention can be prepared as a hollow structure. The hollow structure can be of any shape, preferably a triangular structure that maintains geometric similarity to the outer contour of the fiber. By making the inner and outer contours substantially consistent, the fiber wall thickness can be made substantially uniform in the circumferential direction, thereby: reducing local stress concentration; improving fiber cross-sectional stability; and reducing cross-sectional collapse or deformation during spinning.

[0029] The hollowness of a fiber can be determined using conventional calculation methods in this field. It is calculated by measuring the cross-sectional area of ​​the fiber using the following formula: Fiber hollowness rate = (Total volume of fiber cavities / Total volume of fiber) * 100% In this invention, the hollowness of the fiber is preferably 1%-30%.

[0030] In the actual preparation process, in order to obtain fine denier and highly irregular fibers that are close to the texture of silk, it is necessary to achieve effective cooling while maintaining the stability of the cross-sectional shape.

[0031] For fine denier fibers with high anisotropy, small monofilament fineness, and complex structures, it is necessary to maintain the anisotropy shape through strong airflow while simultaneously cooling it uniformly and slowly. Traditional single-sided and ring-shaped airflow methods cannot meet these requirements. Therefore, this invention employs a two-stage airflow cooling method. The first stage of airflow uses higher air pressure and higher temperature to rapidly reduce the temperature of the nascent fiber and increase its viscosity, thereby improving the melt's resistance to deformation and facilitating the initial stabilization of the anisotropic cross-sectional profile. Simultaneously, the relatively high airflow temperature prevents a significant drop in the spinneret surface temperature, thus preventing fiber brittleness or surface defects. The second stage of airflow uses lower air pressure and lower temperature to further cool the fiber uniformly, ensuring consistent circumferential heat transfer conditions and achieving isotropic and stable cooling. During this process, the fiber cross-sectional structure is maintained until the subsequent drawing stage and final shaping.

[0032] In the second stage of air blowing, a forward blowing method is used. This forward blowing method refers to airflow blowing along the spinning direction. For example... Figure 1 As shown, a represents side-blowing air, b represents circumferential airflow, and c represents forward-blowing airflow.

[0033] The forward airflow method can reduce the disturbance of the fiber cross section by the transverse airflow while ensuring cooling efficiency, thus helping to maintain the stability of the irregular structure.

[0034] By combining two-stage gradient air blowing with forward air blowing, the cooling rate of the fiber can be gradient controlled, thereby improving the forming stability of highly irregular fibers.

[0035] The fibers described in this invention can be prepared using conventional spinnable polymers, including but not limited to: polyester polymers; polyamide polymers; and other thermoplastic polymers suitable for melt spinning or solution spinning. The type of material is not a limiting factor in this invention.

[0036] Example The present invention will be further illustrated below through specific embodiments. It should be noted that, unless otherwise specified, the methods used in this embodiment are conventional methods in the art.

[0037] (1) Fabric luster Fabric gloss was tested using an LFY-224 fabric gloss meter manufactured by Shandong Textile Science Research Institute. The applicable standard was GB / T8686-1988 "Test Method for Fabric Gloss". Each fabric was tested 12 times at different locations, and the average value was calculated.

[0038] Gloss is evaluated using a gloss rating scale: A: less than 39, B: 39-43, C: 43-47, D: 47-52, E: greater than 52 (Gc value) (2) Moisture absorption and perspiration performance test The dynamic contact angles of fibers with different cross-sectional shapes were tested using an optical contact angle meter.

[0039] The moisture wicking capacity of fibers is evaluated by the moisture wicking rating: A: less than 70, B: 70-75, C: 75-80, D: 80-85, E: greater than 85 (advance contact angle °).

[0040] (3) Section parameters The fiber cross-section was observed using a Keyence (China) Co., Ltd. VHX-X1F ultra-depth-of-field optical microscope. Based on the captured images, [the following is a description of the process, not a direct translation]: Figure 2 The positional parameters shown are measured, including: circumcircle diameter. Diameter of the inscribed circle OA is the distance from the centroid O of the cross section to the front end A of the protrusion; OB is the distance from the centroid O to the bottom B of the Y-shaped groove; and the width of the narrowest part of the main arm at the corner. Maximum width of the Y-shaped groove at the end The included angle θ between the pair of protrusions forming the Y-shaped groove. Measure 10 fibers and take the average value.

[0041] Example 1 Polyethylene terephthalate (PET) chips with an intrinsic viscosity of 0.68±0.010 dL / g and a corresponding melt flow rate of 9.6 g / 10 min (260 ℃ / 2.16 kg) were selected as the spinning raw material (supplier: Suzhou Hengli Petrochemical Co., Ltd., China).

[0042] Place the PET chips in a dryer and dry them at 90℃ for 2 hours, 110℃ for 2 hours, 130℃ for 2 hours, and then at 160℃ for 4-6 hours to complete the pre-crystallization and drying of the PET chips.

[0043] The PET chips are conveyed by a screw and heated and melted in zones 1-6, then discharged at a speed of 18.48 cm. 3 A pump feed rate of / min flows into the spinning assembly, and after being extruded from the spinneret, it undergoes air cooling, passing through a no-airflow zone, a first-stage airflow zone, and a second-stage airflow zone, such as... Figure 3 As shown.

[0044] The cooled nascent fibers are treated with spinning oil and then wound at a spinning speed of 2800 m / min to obtain pre-oriented POY yarn. The yarn is then subjected to a post-drawing process to obtain fibers of the target specifications. Specific spinning process parameters are shown in Tables 1 and 2.

[0045] Table 1:

[0046] Fabric manufacturing The obtained fibers were used to weave a double rib knit fabric using a CMS530kiW industrial-grade computerized flat knitting machine from the German company STOLL. The structure was set as double rib, with 1 ply, 20 needles, a loop length of 10mm, a machine speed of 0.15m / s, and a tension of 8-12%.

[0047] Comparative Examples 1-3 The specific process of air blowing and cooling was adjusted, and the spinning was carried out in accordance with the method of Example 1. The specific air blowing process and spinning results are shown in Table 2.

[0048] Table 2

[0049] As shown in Table 2, the two-stage blowing process can improve the retention of fiber cross-sectional structure, thereby achieving a higher degree of irregularity. When the second stage of blowing adopts a forward blowing method, the degree of fiber cross-sectional deformation is further reduced, and the irregularity value is more stable.

[0050] This indicates that the combination of two-stage air blowing and co-blowing is beneficial to improving the cross-sectional stability during the fiber forming process, and is especially suitable for the preparation of irregularly shaped fibers with high irregularity and small monofilament fineness.

[0051] Examples 2-7 By changing the spinneret structure, fiber samples with cross-sectional parameters as shown in Tables 3 and 4 were obtained. All other spinning processes and weaving methods were performed according to Example 1. The luster of the resulting fabrics and the moisture absorption and wicking properties of the fibers were tested, and the results are listed in Tables 3 and 4.

[0052] Comparative Examples 4-14 By changing the spinneret, fiber samples with cross-sectional parameters as shown in Tables 3 and 4 were obtained, while the remaining process conditions remained the same as in Example 1. The fabric gloss and moisture-wicking properties were tested, and the results are listed in Tables 3 and 4.

[0053] In this invention, the fineness of the fiber monofilament is 0.8–5.6 dtex. When the fineness is less than 0.8 dtex, the bending recovery of the single fiber decreases, the structural support capacity weakens, and the elasticity of the fabric decreases; at the same time, excessively fine fibers have relatively weak color development during the dyeing process and are prone to producing fuzz during post-processing.

[0054] When the fineness exceeds 5.6 dtex, fiber stiffness increases, and the fabric feels harder; simultaneously, the number of capillary channels decreases, reducing wicking performance. In Comparative Examples 13 and 14, larger monofilament fineness corresponds to reduced moisture wicking properties. Therefore, the aforementioned fineness range achieves a relatively balanced overall performance in terms of resilience, hand feel, and wicking properties.

[0055] For irregularly shaped fibers, the degree of irregularity is usually characterized by cross-sectional geometric features. This invention uses relative radial irregularity (%) as an evaluation index, defined as: .

[0056] Where d1 is the diameter of the circumcircle and d2 is the diameter of the incircle.

[0057] Preferred range is %.

[0058] When this ratio is small, the fiber cross-section tends to be circular, the protrusion features are not obvious, the longitudinal groove space is insufficient, and the gloss control ability and capillary wicking effect are relatively limited. When this ratio is too large, the protrusion structure is too prominent, the overall stiffness decreases, and the protrusion part is prone to deformation during processing or under pressure, affecting the structural stability. The above range can ensure the formation of the protrusion structure and the formation of longitudinal groove space between the protrusions, which is conducive to the establishment of capillary wicking channels. In comparative examples 7, 9, and 11, due to the relative radial anisotropy deviating from the above range, their gloss and moisture wicking performance are lower than those of the example samples.

[0059] Regarding the groove depth ratio, the distance from the centroid O of the cross-section to the front end A of the protrusion is defined as OA, and the distance from the centroid O to the bottom B of the Y-shaped groove is defined as OB. In this invention, the OA / OB ratio is preferably maintained in the range of 1.05-2. When this ratio is close to 1, the groove depth is shallow, the corners tend to be gentle, and the groove volume is limited; when this ratio is too large, the groove is too deep, the edge wall thickness is reduced, and deformation is easily generated during forming, spinning, or post-processing, which may increase the risk of fibrillation.

[0060] Width of the narrowest part of the main arm at the corner Maximum width of the Y-shaped groove at the end In this invention The preferred range is 0.8-2.2. This ratio, along with other dimensional constraints, ensures a "wide-narrow-wide" gradient space between the main arm and the end "Y"-shaped structure, which helps liquid moisture to remain stably in the groove and migrate quickly under the action of pressure difference, and also increases the diffuse reflection of the fabric.

[0061] When the ratio is less than 0.8, the root of the main arm is too narrow, resulting in insufficient bending stiffness of the single fiber, making the fabric prone to collapse and lacking support. When the ratio exceeds this range, the ability to control the groove structure decreases, and the wicking effect and gloss performance are reduced. In Comparative Examples 10 and 12, this ratio deviates from the above-mentioned preferred range, and their gloss and moisture wicking performance are significantly weaker than those of the embodiments.

[0062] The preferred range for the included angle θ1 between the two small blades forming the "Y"-shaped groove is 30°-120°. When θ1 is less than 30°, the fine structures at the tips tend to stick together during extrusion due to the viscoelasticity of the polymer. When θ1 is greater than 120°, the "Y"-shaped opening is too large, the structure tends to be straight, and the groove disappears. In Comparative Examples 4, 7, and 8, this parameter deviates from the preferred range, and their overall performance in terms of gloss and moisture wicking is significantly weaker than that of the examples.

[0063] Table 3

[0064] Table 4

[0065] For the moisture-wicking performance test, the specific test results are as follows: Figure 9As shown in the figure. The test results show that the cross-sectional shape of the fiber has a significant impact on its wetting behavior. Among them, the triangular grooved fiber of Example 1 has the lowest advancing contact angle (68.5°), exhibiting the best water spreading ability and surface hydrophilicity; this value is significantly lower than that of the triangular fiber of Comparative Example 6 (85.4°) and the circular fiber of Comparative Example 5 (80.6°). The surfaces of circular and ordinary triangular fibers are relatively smooth and lack continuous capillary groove structure, resulting in relatively weak liquid spreading ability. The triangular grooved fiber of the present invention increases surface roughness and capillary effect through its small groove structure, thereby promoting the directional transport of liquid, optimizing the fiber groove structure, and exhibiting better liquid management performance.

[0066] This invention employs a specific cross-sectional structural design, enabling a single fiber cross-section to simultaneously contain both "large flat surfaces" and "small grooves" structural units. When light strikes the grooved area, it undergoes multiple reflections within the groove due to the angle between the inner walls, gradually dispersing the reflection direction and thus increasing the proportion of diffuse reflection. Simultaneously, specular reflection occurs in the large flat surface area, which helps maintain the overall brightness level. The synergistic effect of these two elements allows the fabric to maintain high brightness while possessing a softer visual effect.

[0067] To address the issue of deformation during the forming process of the aforementioned specific cross-sectional structures, this invention further designs a multi-segment airflow cooling method. By controlling the melt cooling rate through segmented airflow, the stability of the cross-sectional structure is improved; combined with the forward airflow process, the surface of the irregularly shaped cross-section fibers can be cooled uniformly and isotropically, thereby better preserving the irregular fiber structure.

[0068] The embodiments of the present invention have now been described in detail. To avoid obscuring the concept of the invention, some details known in the art have not been described. Those skilled in the art will fully understand how to implement the technical solutions disclosed herein based on the above description.

[0069] While specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A fiber with an irregular cross-section, characterized in that, The fibers are formed from polymers; The cross-section of the fiber has a basic structure with a triangular distribution; The reference structure has three corners; A pair of protrusions are provided at each corner position; Two protrusions located at the same corner are directly connected to each other, forming a Y-shaped groove at the vertex of the corner; Two adjacent convex regions located at different corner positions are connected to each other by a continuous straight or curved profile. The straight or curved profiles constitute the three boundary profiles of the baseline structure of the triangular distribution.

2. The irregular cross-section fiber according to claim 1, characterized in that, A pair of protrusions located at the same corner are symmetrically distributed about the angle bisector of that corner.

3. The irregular cross-section fiber according to any one of claims 1-2, characterized in that, The reference structure with the triangular distribution forms a hollow cavity inside.

4. The irregular cross-section fiber according to claim 3, characterized in that, The hollowness of the fiber is 1%-30%.

5. The irregular cross-section fiber according to claim 3, characterized in that, The hollow cavity is triangular in the cross-section of the fiber.

6. The irregular cross-section fiber according to claim 1, characterized in that, The circumcircle diameter of the reference structure Reduce incircle diameter With circumcircle diameter The ratio satisfies: 45% %； The ratio of the distance OA from the centroid O of the cross section to the front end A of the protrusion to the distance OB from the centroid O to the bottom B of the Y-shaped groove, OA / OB is between 1.05 and 2. The width of the narrowest part of the main arm at the corner Maximum width of the Y-shaped groove at the end ratio Between 0.8 and 2.2; The included angle θ between the pair of protrusions forming the Y-shaped groove ranges from 30° to 120°. Monofilament fineness is 0.8-5.6 dtex.

7. The method for preparing irregularly shaped cross-section fibers according to any one of claims 1-6, characterized in that, Step 1: Place the fiber raw material in a dryer to complete the pre-crystallization and drying process; Step 2: The obtained fiber raw material is melt-spun and extruded through a spinneret to form nascent fibers; Step 3: After the nascent fibers are extruded from the spinneret, they enter the air-cooling area for cooling. Step 4: After oiling, winding, and stretching, the finished fiber is obtained.

8. The method for preparing irregularly shaped cross-section fibers according to claim 7, characterized in that, The cooling process in the air-blowing cooling zone includes: The first section is windy, the second section is windy. The second airflow area is located below the first airflow area. The blowing pressure and temperature of the second stage of blowing are both lower than those of the first stage.

9. The method for preparing irregularly shaped cross-section fibers according to claim 8, characterized in that, The first stage of air blowing uses a circular air blowing method; The second section of airflow uses a forward airflow method.

10. A textile comprising the irregularly shaped cross-section fibers as described in any one of claims 1-6.

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