Preparation method of special-shaped hollow fiber, special-shaped hollow fiber and application of special-shaped hollow fiber

Abstract

The invention discloses a preparation method of a special-shaped hollow fiber, the special-shaped hollow fiber and application of the special-shaped hollow fiber, and belongs to the technical field of fiber fabric. The preparation method comprises the following steps: (1) extruding a polyethylene glycol terephthalate melt through a special-shaped spinneret plate, cooling and curing to obtain a fiber bundle, oiling the fiber bundle, and winding to obtain a pre-oriented yarn; (2) stretching and deforming the pre-oriented yarn to obtain the special-shaped hollow fiber; the special-shaped spinneret plate is provided with spinneret orifices which are evenly distributed, and the section of each spinneret orifice is of a multi-leaf-shaped hollow structure. A solid core column A is arranged in the center of the spinneret hole, and a solid core column B is arranged in each leaf area of the multi-leaf-shaped hollow structure. The solid core column A and the solid core column B are connected with the outer contours of the spinneret orifices through supporting ribs distributed in the radial direction. The fiber prepared by the preparation method provided by the invention has excellent mechanical properties, high hollowness and good structural stability.

Description

Technical Field

[0001] This invention relates to the field of fiber fabric technology, and in particular to a method for preparing irregularly shaped hollow fibers, irregularly shaped hollow fibers and their applications. Background Technology

[0002] As consumers increasingly demand comfort, functionality, and differentiation in textiles, traditional round-section synthetic fibers are proving insufficient in terms of luster, bulk, warmth, and hand feel. Shaped fibers and hollow fibers, as important differentiating agents, demonstrate advantages in enhancing fabric luster, bulk, and warmth by mimicking the cross-sectional shape of natural fibers and trapping still air, respectively. However, in current technologies, it is often difficult to simultaneously achieve the advantages of shaped and hollow fibers. Significant technical bottlenecks arise, particularly when combining high shapedness (e.g., multi-lobed) with high hollowness (>30%), as detailed below:

[0003] Poor spinnability: The high degree of irregularity and high hollowness place extremely high demands on spinneret design and melt rheology. After the melt is extruded through the irregular spinneret orifice, it is very easy to shrink back under the action of surface tension, making it difficult to maintain the preset complex cross-sectional shape, resulting in more breakage and fuzz during the spinning process and poor production stability.

[0004] Unstable structure: When high-density hollow fibers are subjected to mechanical tension during subsequent stretching, false twisting deformation and weaving, the hollow part is easily flattened and collapsed, causing the ideal air insulation layer to fail, the warmth retention performance to drop significantly, and also affecting the feel and fullness of the fabric.

[0005] Balancing performance is difficult: maintaining the structure often requires sacrificing other properties. For example, reducing the draw ratio can reduce breakage, but it can lead to insufficient fiber strength; increasing the cooling rate helps with setting, but it may cause internal stress concentration, affecting dyeing uniformity and hand feel.

[0006] Therefore, there is an urgent need in this field for an innovative technical solution that can synergistically solve the problems of spinnability, structural stability and overall performance balance of high-dimensional and high-hollow fibers, and develop high-quality fiber fabrics that combine excellent luster, ultra-high warmth retention, lightweight texture and stable structure. Summary of the Invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing irregularly shaped hollow fibers, and irregularly shaped hollow fibers and their applications. The fibers prepared by the method have both high irregularity and high hollowness, and possess excellent mechanical properties, high hollowness, and good structural stability.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] This invention provides a method for preparing irregularly shaped hollow fibers, comprising the following steps:

[0010] (1) Polyethylene terephthalate melt is extruded through a shaped spinneret, cooled and solidified to obtain fiber bundles, which are then oiled and wound to obtain pre-oriented yarns;

[0011] (2) The pre-oriented yarn is stretched and deformed to prepare the shaped hollow fiber;

[0012] The irregularly shaped spinneret is provided with uniformly distributed spinneret holes, and the cross-section of the spinneret holes has a multi-leaf hollow structure.

[0013] A solid core column A is provided at the center of the spinneret hole, and a solid core column B is provided in each leaf area of ​​the multi-leaf hollow structure.

[0014] The solid core A and solid core B are respectively connected to the outer contour of the spinneret orifice through radially distributed support ribs.

[0015] The cross-section of the fiber extruded through the aforementioned irregular spinneret is multi-lobed, and the center of the multi-lobed shape is a hollow structure. Each lobe region of the multi-lobed shape also contains a hollow structure.

[0016] The cross-sections of the solid core A and solid core B may be the same or different.

[0017] Preferably, the cross-sections of the solid core A and solid core B are independently selected from circles, triangles, squares or rectangles.

[0018] The number of solid core pillars A and solid core pillars B can be the same or different.

[0019] Preferably, the number of solid core pillars A and B in this invention is independently selected from an integer between 1 and 5. This invention utilizes the aforementioned irregularly shaped spinneret to achieve irregularly shaped hollow spinning. Due to the multi-leaf design of the spinneret orifices, the irregular cross-section of the fiber increases the fiber's surface area and cohesion, resulting in a fabric bulkiness 5%-8% higher than that of fibers with round cross-sections, a softer and fuller feel, and significantly improved anti-pilling and anti-fuzzing properties. Furthermore, the irregular cross-section increases the fiber's specific surface area, increasing the dyeing rate by 25% and resulting in higher dyeing brightness. In addition, the fiber exhibits a luster effect similar to natural silk, with light refracting and splitting on the fiber surface, presenting a soft, shimmering effect.

[0020] The cooling and curing process described in this invention employs a segmented cooling process using slow cooling air and rapid cooling air. Slow cooling air is used at a distance of 5-10 mm from the irregular spinneret orifice, while rapid cooling air is used at a distance of 10-25 mm from the irregular spinneret orifice.

[0021] This invention optimizes cooling and curing conditions to prevent fibers from sticking together, thus maintaining the irregular hollow structure.

[0022] Preferably, the cooling and curing conditions of this invention are as follows:

[0023] At a distance of 5-10 mm from the irregularly shaped spinneret, the wind speed is 0.2-0.4 m / s and the temperature is 25℃-30℃;

[0024] At a distance of 10-25 mm from the irregularly shaped spinneret, the wind speed is 0.5-0.8 m / s and the temperature is 18℃-22℃;

[0025] The wind speed of the cooling air is more preferably 0.3 m / s, and the temperature is more preferably 28℃;

[0026] The wind speed of the sudden cooling air is more preferably 0.6 m / s, and the temperature is more preferably 20°C.

[0027] Preferably, the conditions for the tensile deformation in this invention are:

[0028] The draw ratio is controlled between 1.50 and 1.55;

[0029] The tensile deformation includes false twisting treatment;

[0030] The twist coefficient of the false twist treatment is controlled between 0.90 and 0.93.

[0031] This invention combines the irregular hollow spinning process with the segmented cooling process, enabling the polyethylene terephthalate melt to quickly stabilize its irregular cross-section after extrusion, preventing shrinkage deformation caused by surface tension, significantly reducing end breakage and fuzzing during the spinning process, greatly improving production stability, and effectively solving the spinnability problem when combining high irregularity and high hollowness.

[0032] The present invention does not impose any special limitations on the equipment used in the segmented cooling process; any equipment well known to those skilled in the art is acceptable.

[0033] In some specific embodiments of the present invention, a gradient cooling fan box is preferably used for cooling and curing (segmented cooling).

[0034] After the segmented cooling is completed, the yarn is oiled and wound to obtain pre-oriented yarn.

[0035] The pre-oriented yarns are then stretched and deformed to improve the extensibility of the fiber fabric and achieve a good anti-wrinkle effect.

[0036] The stretching ratio of the stretching deformation is more preferably 1.52, 1.55, or 1.50; and more preferably 1.52.

[0037] The tensile deformation includes a false twist treatment, wherein the false twist coefficient of the false twist treatment is more preferably 0.91, 0.93, or 0.91; and more preferably 0.91.

[0038] The false twist degree of the false twist treatment is preferably 2350-2550 twists / meter; more preferably 2350 twists / meter, 2450 twists / meter, or 2550 twists / meter.

[0039] The speed ratio D / Y of the false twisting treatment (where D is the surface linear velocity of the false twist and Y is the running linear velocity of the fiber) is preferably 1.70-1.75; more preferably 1.72.

[0040] The tensile deformation includes two heat setting processes. The first heat setting temperature is preferably 105℃-120℃, more preferably 110℃. The second heat setting temperature is preferably 125℃-135℃, more preferably 130℃.

[0041] The present invention effectively eliminates internal stress in fibers through the above two heat setting processes, improves dimensional stability and dyeing uniformity, and enables the fibers to maintain good shape and hollow structure after multiple washings and uses, resulting in excellent functional durability.

[0042] The present invention does not impose any special limitations on the equipment used in the tensile deformation process; any equipment known to those skilled in the art is acceptable.

[0043] In some specific embodiments of the present invention, a stretching deformation machine is preferably used.

[0044] The present invention does not have any special limitations on the equipment used for heat setting after stretching deformation; any equipment known to those skilled in the art is acceptable.

[0045] In some specific embodiments of the present invention, a hot box is preferably used for the first and second heat setting.

[0046] Preferably, the multi-leaf hollow structure of the present invention is selected from four-leaf, six-leaf, or eight-leaf shapes; more preferably, it is an eight-leaf shape.

[0047] Preferably, the number of supporting ribs in this invention is 3-6; more preferably, it is 4.

[0048] Preferably, the polyethylene terephthalate melt is obtained by melting dried polyethylene terephthalate chips.

[0049] The intrinsic viscosity of the polyethylene terephthalate chips is 0.70-0.74 dl / g.

[0050] The polyethylene terephthalate melt is uniform and stable, and can be conveyed to the shaped spinneret for spinning, further realizing the preparation of fibers that can be both shaped and hollow.

[0051] Preferably, the extrusion temperature is 285℃-295℃.

[0052] Preferably, the amount of oil applied is 0.5wt%-0.8wt%; more preferably, it is 0.6wt%, 0.8wt%, or 0.5wt%.

[0053] Preferably, the winding speed is 2800-3200 m / min. More preferably, it is 2800 m / min, 3000 m / min, or 3200 m / min.

[0054] The present invention also provides an irregularly shaped hollow fiber, which is prepared by the above-described preparation method.

[0055] Preferably, the hollowness of the irregularly shaped hollow fiber is 30%-45%;

[0056] The appropriate hollowness allows the internal cavities of the irregularly shaped hollow fibers to effectively trap air, forming an ideal air insulation layer. Compared to traditional round cross-section fibers, the insulation performance is improved by more than 65%, while the fiber density is reduced by 20%-30%, achieving a perfect combination of lightweight and warmth.

[0057] Preferably, the shaped hollow fiber of the present invention has a tensile strength ≥3.4 cN / dtex and a breaking elongation of 25%-28%;

[0058] Preferably, the elastic recovery rate of the irregularly shaped hollow fiber is ≥81%, and the compressive elasticity is ≥51%.

[0059] Because the fibers have good tensile strength and elastic recovery, they are not prone to fuzzing or breakage during weaving, resulting in high weaving efficiency and a finished fabric with a full hand feel and good crispness.

[0060] Preferably, after being compressed for 1 minute under a load of 0.5 cN / dtex, the hollow area retention rate of the irregular hollow fiber is not less than 85%.

[0061] The high hollow area retention rate makes the fiber structure highly stable, ensuring that the hollow structure is not prone to collapse during subsequent weaving and use, and that the heat retention performance is long-lasting and stable.

[0062] The present invention also provides a fabric prepared from nylon, spandex and the above-mentioned irregular hollow fibers.

[0063] Compared with the prior art, the method for preparing irregularly shaped hollow fibers provided by the present invention includes the following steps: (1) extruding polyethylene terephthalate melt through an irregularly shaped spinneret, cooling and solidifying it to obtain fiber bundles, oiling them, and winding them to obtain pre-oriented yarns; (2) stretching and deforming the pre-oriented yarns to obtain the irregularly shaped hollow fibers; the irregularly shaped spinneret is provided with uniformly distributed spinneret holes, and the cross-section of the spinneret holes is a multi-leaf hollow structure; a solid core column A is provided at the center of the spinneret hole, and a solid core column B is provided in each leaf area of ​​the multi-leaf hollow structure; the solid core column A and the solid core column B are respectively connected to the outer contour of the spinneret hole through radially distributed support ribs. The fibers prepared by the method of the present invention have excellent mechanical properties, high hollowness, and good structural stability. Attached Figure Description

[0064] Figure 1 This is a process flow diagram of the preparation method described in this invention. Detailed Implementation

[0065] To further illustrate the present invention, the following describes in detail the preparation method of the irregular hollow fiber and the irregular hollow fiber and its application, with reference to the embodiments.

[0066] Figure 1 This is a process flow diagram of the preparation method described in this invention.

[0067] The method for preparing irregularly shaped hollow fibers provided by the present invention includes the following steps:

[0068] (1) Polyethylene terephthalate melt is extruded through a shaped spinneret, cooled and solidified to obtain fiber bundles, which are then oiled and wound to obtain pre-oriented yarns;

[0069] (2) The pre-oriented yarn is stretched and deformed to prepare the irregular hollow heat-storing and down-proof fiber;

[0070] The irregularly shaped spinneret is provided with uniformly distributed spinneret holes, and the cross-section of the spinneret holes has a multi-leaf hollow structure.

[0071] A solid core column A is provided at the center of the spinneret hole, and a solid core column B is provided in each leaf area of ​​the multi-leaf hollow structure.

[0072] The solid core A and solid core B are respectively connected to the outer contour of the spinneret orifice through radially distributed support ribs.

[0073] The cross-sections of the solid core A and solid core B are independently selected from circles, triangles, squares, or rectangles.

[0074] The number of solid core pillars A and B is independently selected from integers between 1 and 5.

[0075] The cooling and curing conditions are as follows: at a distance of 5-10 mm from the shaped spinneret, the wind speed is 0.2-0.4 m / s and the temperature is 25℃-30℃; at a distance of 10-25 mm from the shaped spinneret, the wind speed is 0.5-0.8 m / s and the temperature is 18℃-22℃.

[0076] The conditions for the tensile deformation are: the stretch ratio is controlled between 1.50 and 1.55; the tensile deformation includes false twisting treatment; the twist coefficient of the false twisting treatment is controlled between 0.90 and 0.93.

[0077] Example 1

[0078] Raw material preparation: Select polyethylene terephthalate chips with an intrinsic viscosity of 0.72 dl / g, and dry them for later use.

[0079] Melt preparation and conveying: The dried polyester chips are added to the screw extruder for melting, with the melting temperature controlled at 290℃-295℃ to form a uniform and stable melt. The melt is then precisely metered by a metering pump and conveyed to the profile spinneret assembly.

[0080] Hollow fiber spinning: The melt is extruded through a specially designed eight-lobed spinneret. The spinneret's spinneret orifices are eight-lobed (with an eight-lobed hollow cross-section), and a core rod A (i.e., a solid core column A with a circular cross-section) is located at the center to form a hollow fiber structure. Each lobe region of the eight-lobed hollow structure is respectively equipped with a core rod B (i.e., a solid core column B with a circular cross-section). Core rods A and B are connected to the outer edge of the spinneret orifice by four evenly distributed support ribs. The extruded melt stream enters a gradient cooling box for cooling and solidification. A slow cooling air with a wind speed of 0.3 m / s and a temperature of 28°C is used at a distance of 5 mm from the spinneret surface, and a rapid cooling air with a wind speed of 0.6 m / s and a temperature of 20°C is used at a distance of 10 mm from the spinneret surface.

[0081] Pre-oriented yarn preparation: The cooled and cured fiber bundles are oiled with an oiling amount of 0.6% and wound at a speed of 3000 m / min to obtain pre-oriented yarn.

[0082] Stretch deformation: The pre-oriented yarn is processed on a stretch deformation machine. The stretch ratio is controlled at 1.52, the temperature of the first heating box is controlled at 110℃, the false twist coefficient k value is controlled at 0.91, the speed ratio D / Y is controlled at 1.72, and the false twist is controlled at 2450 twists / m. The heat setting temperature of the second heating box is controlled at 130℃.

[0083] Example 2

[0084] Raw material preparation: Select polyethylene terephthalate chips with an intrinsic viscosity of 0.74 dl / g, and dry them for later use.

[0085] Melt preparation and conveying: The dried polyester chips are added to the screw extruder for melting, with the melting temperature controlled at 292℃-297℃ to form a uniform and stable melt. The melt is then precisely metered by a metering pump and conveyed to the profile spinneret assembly.

[0086] Hollow fiber spinning: The melt is extruded through a specially designed hexagonal spinneret. The spinneret's spinneret orifices are hexagonal (with a hexagonal hollow cross-section). A core rod A (i.e., a solid core column A with a circular cross-section) is located at the center to form the hollow fiber structure. Each lobe region of the hexagonal hollow structure has a core rod B (i.e., a solid core column B with a circular cross-section). Core rods A and B are connected to the outer edge of the spinneret orifices by six evenly distributed support ribs. The extruded melt stream enters a gradient cooling box for cooling and solidification. A slow cooling airflow of 0.4 m / s and 30°C is used at a distance of 8 mm from the spinneret surface, while a rapid cooling airflow of 0.7 m / s and 22°C is used at a distance of 15 mm from the spinneret surface.

[0087] Pre-oriented yarn preparation: The cooled and cured fiber bundles are oiled with an oiling amount of 0.8% and wound at a speed of 3200 m / min to obtain pre-oriented yarn.

[0088] Stretch deformation: The pre-oriented yarn is processed on a stretch deformation machine. The stretch ratio is controlled at 1.55, the temperature of the first heating box is controlled at 120℃, the false twist coefficient k value is controlled at 0.93, the speed ratio D / Y is controlled at 1.75, and the false twist is controlled at 2550 twists / m. The heat setting temperature of the second heating box is controlled at 135℃.

[0089] Example 3

[0090] Raw material preparation: Select polyethylene terephthalate chips with an intrinsic viscosity of 0.70 dl / g, and dry them for later use.

[0091] Melt preparation and conveying: The dried polyester chips are added to the screw extruder for melting, with the melting temperature controlled at 288℃-293℃ to form a uniform and stable melt. The melt is then precisely metered by a metering pump and conveyed to the profile spinneret assembly.

[0092] Hollow fiber spinning: The melt is extruded through a specially designed four-lobed spinneret. The spinneret's spinneret orifices are four-lobed (with a four-lobed hollow cross-section). A core rod A (i.e., a solid core column A with a circular cross-section) is located at the center to form the hollow fiber structure. Each lobe region of the four-lobed hollow structure has a core rod B (i.e., a solid core column B with a circular cross-section). Core rods A and B are connected to the outer edge of the spinneret orifice by three evenly distributed support ribs. The extruded melt stream enters a gradient cooling box for cooling and solidification. A slow cooling air with a velocity of 0.2 m / s and a temperature of 25°C is used at a distance of 10 mm from the spinneret surface, while a rapid cooling air with a velocity of 0.5 m / s and a temperature of 18°C ​​is used at a distance of 25 mm from the spinneret surface.

[0093] Pre-oriented yarn preparation: The cooled and cured fiber bundles are oiled with an oiling amount of 0.5% and wound at a speed of 2800 m / min to obtain pre-oriented yarn.

[0094] Stretch deformation: The pre-oriented yarn is processed on a stretch deformation machine. The stretch ratio is controlled at 1.50, the temperature of the first heating box is controlled at 105℃, the false twist coefficient k value is controlled at 0.90, the speed ratio D / Y is controlled at 1.70, and the false twist is controlled at 2350 twists / m. The heat setting temperature of the second heating box is controlled at 125℃.

[0095] Performance testing

[0096] The performance of the irregular hollow fibers prepared in Examples 1-3 was tested, and the results are shown in Table 1.

[0097] Table 1 Performance test results of the irregular hollow fibers prepared in Examples 1-3

[0098] Test Project Example 1 Example 2 Example 3 Test Standards Linear density (dtex) 33.2 55.0 33.5 GB / T 14343 Fracture strength (cN / dtex) 3.6 3.5 3.4 GB / T 14344 Elongation at break (%) 26.5 28.0 25.2 GB / T 14344 Hollowness (%) 42.5 35.8 31.2 GB / T 14343 Hollow core retention rate after compression (%) 89.2 86.5 85.0 GB / T 6505 Elastic recovery rate (%) 83.5 81.0 81.5 GB / T 6506 Compressive elastic modulus (%) 53.2 51.5 51.0 GB / T 6506

[0099] The test results in Table 1 show that the irregular hollow fiber prepared by this invention has excellent mechanical properties, high hollowness (excellent warmth retention) and good structural stability (good wrinkle resistance), which fully meets the requirements for use in high-end thermal clothing fabrics.

[0100] The irregular hollow fiber prepared by this invention can be further processed into high-end down fabrics.

[0101] Specific application examples are as follows:

[0102] The twisted yarn made from the fibers of this invention is used as warp or weft yarn and interwoven with a nylon FDY filament with a soft luster and a spandex-covered yarn. The irregularly shaped hollow fibers provide the core warmth and loft, and their unique cross-sectional structure enhances fiber cohesion, reduces yarn gaps, and effectively improves down-proofness. The twisting process gives the yarn higher strength and a tighter structure. The introduction of the glossy nylon not only compensates for the lack of luster in polyester fibers, giving the fabric a luxurious, silky visual effect, but also significantly enhances the fabric's abrasion resistance and strength. The spandex ensures the fabric has the necessary elasticity and resilience, improving wearing comfort and preventing down from escaping due to repeated stretching. This multi-component composite fabric ultimately achieves a perfect unity of warmth, down-proofness, high elasticity, lightweight, and luxurious gloss, making it particularly suitable for manufacturing high-end down jackets, winter clothing, and sleeping bags.

[0103] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing irregularly shaped hollow fibers, characterized in that, Includes the following steps: (1) Polyethylene terephthalate melt is extruded through a shaped spinneret, cooled and solidified to obtain fiber bundles, which are then oiled and wound to obtain pre-oriented yarns; (2) The pre-oriented yarn is stretched and deformed to prepare the shaped hollow fiber; The irregularly shaped spinneret is provided with uniformly distributed spinneret holes, and the cross-section of the spinneret holes has a multi-leaf hollow structure. A solid core column A is provided at the center of the spinneret hole, and a solid core column B is provided in each leaf area of ​​the multi-leaf hollow structure. The solid core A and solid core B are respectively connected to the outer contour of the spinneret orifice through radially distributed support ribs.

2. The preparation method according to claim 1, characterized in that, The cross-sections of the solid core A and solid core B are independently selected from circles, triangles, squares, or rectangles.

3. The preparation method according to claim 2, characterized in that, The number of solid core pillars A and B is independently selected from integers between 1 and 5.

4. The preparation method according to any one of claims 1-3, characterized in that, The conditions for cooling and solidification are as follows: At a distance of 5-10 mm from the irregularly shaped spinneret, the wind speed is 0.2-0.4 m / s and the temperature is 25℃-30℃; At a distance of 10-25 mm from the irregularly shaped spinneret, the wind speed is 0.5-0.8 m / s and the temperature is 18℃-22℃; The condition for the tensile deformation is: The draw ratio is controlled between 1.50 and 1.55; The tensile deformation includes false twisting treatment; The twist coefficient of the false twist treatment is controlled between 0.90 and 0.

93.

5. The preparation method according to claim 1, characterized in that, The multi-leaf hollow structure is selected from four-leaf, six-leaf, or eight-leaf shapes; The number of supporting ribs is 3-6.

6. The preparation method according to claim 1, characterized in that, The polyethylene terephthalate melt is obtained by melting dried polyethylene terephthalate chips. The intrinsic viscosity of the polyethylene terephthalate chips is 0.70-0.74 dl / g; The extrusion temperature is 285℃-295℃.

7. The preparation method according to claim 1, characterized in that, The amount of oil applied is 0.5wt%-0.8wt%; The winding speed is 2800-3200 m / min.

8. A type of irregularly shaped hollow fiber, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.

9. The irregularly shaped hollow fiber according to claim 8, characterized in that, The hollowness of the irregularly shaped hollow fiber is 30%-45%; The shaped hollow fiber has a tensile strength ≥3.4 cN / dtex and a breaking elongation of 25%-28%; The shaped hollow fiber has an elastic recovery rate of ≥81% and a compressive elasticity of ≥51%. After being compressed for 1 minute under a load of 0.5 cN / dtex, the hollow fiber retains at least 85% of its hollow area.

10. A fabric, characterized in that, It is prepared from nylon, spandex and the irregular hollow fiber as described in claim 8 or 9.

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