A hollow nylon fiber with a core and sheath, its preparation method, and the fabric thereof.

Abstract

This invention provides a hollow nylon fiber with a core and sheath, its preparation method, and the fabric thereof, belonging to the field of textile fabrics. The fiber sequentially comprises a coaxially composite PA6 sheath and a high-viscosity PA6 core layer, the high-viscosity PA6 core layer having a cavity. The viscosity of the high-viscosity PA6 material in the high-viscosity PA6 core layer is higher than that of the PA6 material in the PA6 sheath. Far-infrared functional particles are uniformly distributed in the high-viscosity PA6 core layer. In the hollow nylon fiber structure of this invention, the high-viscosity PA6 core layer provides support, preventing the hollow nylon from being crushed. The far-infrared functional masterbatch distributed in this core layer enhances the warmth retention of the hollow nylon, while the PA6 sheath structure also prevents the far-infrared functional masterbatch from being exposed, thereby ensuring the quality of the yarn and fabric.

Description

Technical Field

[0001] This invention belongs to the field of textile fabric technology, and particularly relates to a hollow nylon fiber with a core and sheath, its preparation method, and the fabric thereof. Background Technology

[0002] As consumers demand more diverse winter textile products and a higher quality of life, they no longer simply need warm clothing to maintain body temperature and prevent colds and other illnesses. They also require lightweight, comfortable clothing that meets the specific needs of different usage scenarios. Currently, to achieve better warmth, winter textiles and clothing typically increase fabric thickness to increase the amount of stagnant air, thus improving insulation. However, this can easily result in overly bulky garments and reduced comfort.

[0003] Among various textile fibers, nylon fiber is characterized by its low modulus and good skin-friendliness, and is often used in products worn close to the skin. Nylon fiber, scientifically known as polyamide (PA) fiber, was originally the trade name for polyhexamethylene adipamide produced by DuPont, commonly abbreviated as Nylon 66; while PA6 fiber is nylon 6 fiber produced by the ring-opening polymerization of caprolactam. Polyamide fiber generally has a specific gravity of around 1.14, making it lighter than polyester fiber. It can be processed into fine, soft filaments and can also be formed into hollow fibers. Therefore, the comfort, lightweight, and warmth of nylon fiber represent the consumer demand for nylon-based clothing products.

[0004] However, the hollow ratio of existing ordinary hollow thermal nylon fibers is generally around 10-20%, which makes them easy to be compressed during subsequent weaving and dyeing processes, affecting the thermal insulation performance of the fibers and fabrics. Summary of the Invention

[0005] In view of the shortcomings of the prior art as described above, the present invention provides a hollow nylon fiber with a core and sheath, a method for preparing the fiber and a fabric thereof. The hollow nylon fiber provided by this application has excellent warmth retention and heat insulation properties, good quality, and is suitable for use in winter clothing fabrics.

[0006] This invention provides a hollow nylon fiber with a core and a sheath, comprising a coaxially composite PA6 sheath and a high-viscosity PA6 core, wherein the high-viscosity PA6 core has a cavity; the viscosity of the high-viscosity PA6 material in the high-viscosity PA6 core is higher than the viscosity of the PA6 material in the PA6 sheath, and far-infrared functional particles are uniformly distributed in the high-viscosity PA6 core.

[0007] In embodiments of this application, the hollow nylon fiber in the core has a circular or elliptical cross-section.

[0008] In the embodiments of this application, the hollowness of the core-sheath hollow nylon fiber is 25%-45%.

[0009] In the embodiments of this application, the relative viscosity of the PA6 material in the PA6 skin layer is 2.5-2.8; the relative viscosity of the high viscosity PA6 material in the high viscosity PA6 core layer is 3.2-3.7.

[0010] In embodiments of this application, the far-infrared functional particles comprise graphene powder; the graphene powder accounts for 0.1wt% to 0.5wt% of the fiber mass.

[0011] In the embodiments of this application, the mass ratio of the PA6 skin layer to the high-viscosity PA6 core layer is 1:9 to 3:7.

[0012] This application provides a method for preparing core-sheath hollow nylon fibers, comprising the following steps:

[0013] PA6 chips of ordinary viscosity are fed into the first screw of a twin-screw extruder for melt extrusion to obtain a skin layer spinning melt; high-viscosity PA6 chips and far-infrared functional masterbatch are blended and fed into the second screw of the twin-screw extruder for melt extrusion to obtain a core layer spinning melt; the temperature of melt extrusion in the first screw is lower than the temperature of melt extrusion in the second screw;

[0014] The sheath spinning melt and the core spinning melt are spun through a sheath-core type composite spinning assembly, using different hollow composite spinnerets to adjust the hollowness of the fibers, to obtain sheath-core hollow nylon fibers with a cavity in the core layer.

[0015] In the embodiments of this application, the ordinary viscosity PA6 chips, high viscosity PA6 chips, and far-infrared functional masterbatch are all dried raw materials; the moisture content of the dried ordinary viscosity PA6 chips and the dried high viscosity PA6 chips is less than 50 ppm.

[0016] In the embodiments of this application, the melt extrusion temperature in the first screw is 260-273°C; the melt extrusion temperature in the second screw is 275-290°C.

[0017] The core-sheath composite spinning assembly has a sheath spinning temperature of 260-273℃ and a core spinning temperature of 275-290℃; the total spinning speed is 1500-3000 m / min; and the draw ratio of the hollow nylon fiber in the core-sheath assembly is 3-5.

[0018] This application provides a fabric comprising: the hollow nylon fiber with core and sheath described above or the hollow nylon fiber with core and sheath obtained by the preparation method described above.

[0019] To improve warmth retention, far-infrared functional masterbatches can be added to ordinary single-layer hollow nylon. However, these functional materials are generally concentrated on the surface layer, and because hollow fibers have less surface space than ordinary fibers, they are easily exposed. During subsequent weaving and dyeing processes, the added functional materials can easily wear down weaving equipment and affect dyeing uniformity, leading to defects in the finished product and impacting quality. Therefore, the amount and uniformity of far-infrared functional masterbatches added to existing hollow nylon fibers are difficult to control.

[0020] The hollow nylon fiber with a core and sheath provided by this invention comprises, in sequence, a coaxially composite PA6 sheath and a high-viscosity PA6 core; the high-viscosity PA6 core has a cavity, and far-infrared functional particles are uniformly distributed within the core. In the hollow nylon fiber structure of this invention, the high-viscosity PA6 core provides support, preventing the hollow nylon from being crushed; the far-infrared functional particles distributed within the core enhance the warmth retention of the hollow nylon, while the PA6 sheath structure also prevents the far-infrared functional particles from being exposed, thereby ensuring the quality of the yarn and fabric. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the cross-sectional structure of hollow nylon fibers in the core and sheath provided in some embodiments of the present invention. Detailed Implementation

[0022] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, all reagents and raw materials used in the present invention are commercially available products or products that can be prepared by recognized methods.

[0023] This invention provides a hollow nylon fiber with a core and a sheath, comprising a coaxially composite PA6 sheath and a high-viscosity PA6 core, wherein the high-viscosity PA6 core has a cavity; the viscosity of the high-viscosity PA6 material in the high-viscosity PA6 core is higher than the viscosity of the PA6 material in the PA6 sheath, and far-infrared functional particles are uniformly distributed in the high-viscosity PA6 core.

[0024] The hollow nylon fiber provided in this application has excellent warmth retention and heat insulation properties, good quality, and is suitable for use in winter clothing fabrics.

[0025] See Figure 1 , Figure 1This is a schematic cross-sectional view of the hollow nylon fiber sheath and core provided in some embodiments of the present invention. Wherein, 1 is the PA6 sheath, 2 is the high-viscosity PA6 core, and 3 is the cavity.

[0026] Hollow fibers are generally chemical fibers with tubular cavities running through the fiber axis; their hollow structure reduces fiber weight and can contain still air, providing a certain degree of warmth retention. Core-sheath composite fibers typically consist of two polymer components layered together in a sheath and core configuration, composited along the fiber axis. The outer polymer layer is the sheath, and the inner polymer layer is the core. Depending on the distribution and arrangement of the sheath and core layers, they are generally concentric composite structures, but there are also eccentric and irregular core-sheath types.

[0027] The hollow nylon fiber described in this embodiment of the invention consists of a three-layer composite structure, from the outside to the inside: a PA6 sheath 1, a high-viscosity PA6 core 2, and a cavity 3. The PA6 sheath 1 is composed of PA6 material of ordinary viscosity, which has a lower viscosity than the high-viscosity PA6 material in the high-viscosity PA6 core 2.

[0028] The high-viscosity PA6 core layer 2 is composed of high-viscosity PA6 components and a small amount of far-infrared functional particles; the far-infrared functional particles are uniformly distributed in the high-strength PA6 core layer 2, and the tubular cavity 3 is located inside the core layer.

[0029] The high-viscosity PA6 mentioned above is an existing material, with the same structural unit as ordinary PA6, [-NH(CH2)5CO-]. The difference lies in the polymerization process, where improvements are made (e.g., catalysts, activators, reaction temperature) to increase the degree of polymerization compared to ordinary viscosity nylon 6, thereby increasing the molecular weight and viscosity. Relative viscosity is defined as the ratio of the dynamic viscosity of a fluid to the dynamic viscosity of water at the same temperature, and is dimensionless; sometimes it also refers to the ratio of the dynamic viscosity of a polymer solution to the dynamic viscosity of a pure solvent at the same temperature. Specifically, the relative viscosity of the PA6 material in the PA6 skin layer 1 is 2.5-2.8, preferably 2.6-2.7; the relative viscosity of the high-viscosity PA6 material in the high-viscosity PA6 core layer 2 is 3.2-3.7, preferably 3.4-3.6, and further preferably 3.5.

[0030] The far-infrared functional particles of the preferred embodiment of the present invention contain graphene powder, which has good heat retention properties; preferably, the graphene powder accounts for 0.1wt% to 0.5wt% of the fiber mass, more preferably 0.5%. The embodiments of the present invention use high-viscosity nylon 6 to form the core layer, so that the cavity portion is maintained during spinning and is not easily crushed. Furthermore, the addition of a far-infrared emitting functional substance (such as a masterbatch containing graphene powder) to the core layer further improves the heat retention performance of the fiber.

[0031] In some embodiments of the present invention, the linear density of the hollow nylon fiber in the core can be 1.3–1.4 dtex. Linear density refers to the mass per unit length of fiber, single yarn, mesh, rope, etc., and is an indicator describing the fineness of yarn. It is expressed in two forms: fixed length system and fixed weight system; the higher the linear density, the thicker the fiber or yarn. Under the same fineness conditions, directly using high-viscosity nylon 6 chips as garment filaments results in a high modulus, which easily leads to poor hand feel and rough product. Moreover, using high-strength yarn to weave on conventional looms easily causes wear and tear on the weaving equipment, reduces production efficiency, and results in abnormal fabric quality.

[0032] In the embodiments of this application, the hollow nylon fiber with sheath and core has a circular or elliptical cross-section, the fiber length is not limited, and the specification can be 50D / 36F (F is the number of holes). The hollowness of the hollow nylon fiber with sheath and core can be 25%-45%, preferably 35%-40%. Furthermore, the mass ratio of the PA6 sheath layer to the high-viscosity PA6 core layer is preferably 1:9 to 3:7, more preferably 20:80.

[0033] This application provides a method for preparing core-sheath hollow nylon fibers, comprising the following steps:

[0034] PA6 chips of ordinary viscosity are fed into the first screw of a twin-screw extruder for melt extrusion to obtain a skin layer spinning melt; high-viscosity PA6 chips and far-infrared functional masterbatch are blended and fed into the second screw of the twin-screw extruder for melt extrusion to obtain a core layer spinning melt; the temperature of melt extrusion in the first screw is lower than the temperature of melt extrusion in the second screw;

[0035] The sheath spinning melt and the core spinning melt are spun through a sheath-core type composite spinning assembly, using different hollow composite spinnerets to adjust the hollowness of the fibers, to obtain sheath-core hollow nylon fibers with a cavity in the core layer.

[0036] The present invention provides a method for preparing hollow nylon fibers with excellent thermal insulation properties and a core-sheath structure. The specific steps are as follows:

[0037] As a preferred method, PA6 polyamide chips of ordinary viscosity and PA6 polyamide chips of high viscosity are respectively dried in a vacuum drum at 90-100℃ until the moisture content is less than 50ppm.

[0038] Then, the dried ordinary viscosity PA6 polyamide chips are fed into the first screw of a twin-screw extruder for melt extrusion at a temperature preferably of 260-273℃ to obtain a skin layer spinning melt; the dried high viscosity PA6 polyamide chips and the dried far-infrared functional masterbatch are blended and fed into the second screw of a twin-screw extruder for melt extrusion at a temperature preferably of 275-290℃ to obtain a core layer spinning melt;

[0039] The sheath and core spinning melts are metered by their respective metering pumps and then fed into the composite spinning box. After passing through the sheath-core type composite spinning assembly, the hollowness of the fiber is adjusted by different hollow composite spinnerets for spinning.

[0040] The viscosity parameters of both ordinary and high-viscosity PA6 are as described above, and commercially available polyamide chips can be used. The far-infrared functional masterbatch is also a commercially available masterbatch containing graphene powder. The masterbatch substrate is high-viscosity PA6, and it contains a high concentration of graphene functional powder particles. The particle size range of the added graphene powder is generally 200-400 nm. The preferred spinning temperature for the sheath-core composite spinning assembly is 260-273℃, and the preferred spinning temperature for the core layer is 275-290℃; the total spinning speed is 1500-3000 m / min. The spinning process includes: extruding a certain hollow fiber stream through a hollow composite spinneret, solidifying and cooling (e.g., by blowing cold air), stretching the resulting nascent fibers, and spinning them to obtain composite fibers. The preferred draw ratio of the hollow nylon fiber in the core and sheath is 3 to 5; the draw temperature can be 120℃ to 160℃, and the preferred cold air temperature is 15℃ to 25℃.

[0041] In this embodiment of the invention, hollow nylon fibers with a core-sheath structure obtained by spinning are processed through subsequent weaving, degreasing, dyeing, color fixing, intermediate inspection, finished product determination, and finished product inspection (each process is a conventional process) to finally produce the finished fabric. For example, a small amount of spandex is usually added during the fabric weaving process; the dyeing process uses nylon dyeing procedures well known to those skilled in the art, and this application has no special limitations.

[0042] That is, this application also provides a fabric comprising: the hollow nylon fiber with core and sheath described above or the hollow nylon fiber with core and sheath obtained by the preparation method described above. The embodiments of the present invention do not impose special limitations on the specifications, structure, weaving, etc., of the fabric; it can be a pure spun or blended fabric, or a woven or knitted fabric.

[0043] Based on the hollow nylon fiber with a core and sheath, the fabric provided in this embodiment of the invention has excellent warmth retention and heat insulation properties, and is of good quality.

[0044] To better illustrate the present invention, further examples are provided below. In the following examples, all raw materials are commercially available products.

[0045] Example 1

[0046] The core-sheath structure of nylon hollow fiber is prepared as follows:

[0047] 1) Ordinary PA6 polyamide chips and high-viscosity PA6 polyamide chips were dried in a vacuum drum at 95°C until the moisture content was less than 50 ppm.

[0048] 2) The dried ordinary PA6 polyamide chips are fed into the first screw of a twin-screw extruder for melt extrusion at a temperature of 270℃ to obtain the skin layer spinning melt; the dried high-viscosity PA6 polyamide chips and the dried far-infrared functional masterbatch are blended and fed into the second screw of a twin-screw extruder for melt extrusion at a temperature of 285℃ to obtain the core layer spinning melt.

[0049] 3) The sheath and core spinning melts are metered by their respective metering pumps and then fed into the composite spinning box. After passing through the sheath-core type composite spinning assembly, the hollowness of the fiber is adjusted by different hollow composite spinnerets, and spinning is carried out. The sheath spinning temperature is 270℃, the core spinning temperature is 285℃, the spinning speed is 2500m / min, the draw ratio is 3.5, the stretching temperature is 150℃, and the cold air temperature is 20℃.

[0050] The viscosity of the PA6 outer layer is 2.6, and the viscosity of the high-viscosity PA6 core layer is 3.5. The mass ratio of the outer layer to the core layer is 20 / 80; the hollow fiber content of the core-shell structure nylon hollow fiber is 35%. The functional powder in the far-infrared functional masterbatch is graphene powder, with a content of 0.5 wt%. The core-shell nylon hollow fiber prepared in this embodiment of the invention has a hollow structure and good quality, as shown in Table 1.

[0051] The obtained core-sheath structure nylon hollow fibers (performance indicators as shown in the table below) are processed through subsequent weaving, degreasing, conventional nylon dyeing, and finishing processes to finally produce the finished fabric, which is a 50D / 48F nylon-spandex air layer knitted fabric (90wt% nylon, 10wt% 30D spandex).

[0052] Table 1 Performance indicators of core-sheath structured nylon hollow fibers in Example 1

[0053]

[0054] Example 2

[0055] The preparation of core-sheath structured nylon hollow fibers is as follows:

[0056] 1) Ordinary PA6 polyamide chips and high-viscosity PA6 polyamide chips were dried in a vacuum drum at 95°C until the moisture content was less than 50 ppm.

[0057] 2) The dried ordinary PA6 polyamide chips are fed into the first screw of a twin-screw extruder for melt extrusion at a temperature of 270℃ to obtain the skin layer spinning melt; the dried high-viscosity PA6 polyamide chips and the dried far-infrared functional masterbatch are blended and fed into the second screw of a twin-screw extruder for melt extrusion at a temperature of 285℃ to obtain the core layer spinning melt.

[0058] 3) The sheath and core spinning melts are metered by their respective metering pumps and then fed into the composite spinning box. After passing through the sheath-core type composite spinning assembly, the hollowness of the fiber is adjusted by different hollow composite spinnerets for spinning. The sheath spinning temperature is 270℃, the core spinning temperature is 280℃, the spinning speed is 2500m / min, the draw ratio is 3.5, the stretching temperature is 150℃, and the cold air temperature is 20℃.

[0059] The relative viscosity of the PA6 chips in the outer layer is 2.6, and the relative viscosity of the high-viscosity PA6 chips in the core layer is 3.2. The mass ratio of the outer layer to the core layer is 10 / 90; the hollow fiber content of the core-sheath structure nylon hollow fiber is 33%. The functional powder in the far-infrared functional masterbatch is graphene powder, with a content of 0.5 wt%. The core-sheath nylon hollow fiber prepared in this embodiment of the invention has a hollow structure and good quality, as shown in Table 2.

[0060] The obtained core-sheath structure nylon hollow fibers are processed through subsequent weaving, degreasing, conventional nylon dyeing, and finishing to finally produce the finished fabric; the fabric is a 50D / 48F nylon-spandex air layer knitted fabric (90wt% nylon, 10wt% 30D spandex).

[0061] Table 2 Performance indicators of core-sheath structured nylon hollow fibers in Example 2

[0062]

[0063] The fabrics obtained in the above embodiments were quantitatively evaluated, and the results are as follows, including a comparative sample with the same specifications. The embodiments of this invention mainly demonstrate the advantage of the hollow structure of this solution being less prone to being crushed by testing the hollow rate of the finished product (which has undergone weaving stretching and extrusion, high-temperature stretching during dyeing and finishing, and high-temperature stretching during setting).

[0064] Table 3 Performance test results of the fabrics obtained in the embodiments of the present invention

[0065]

[0066] The testing methods include:

[0067] Hollowness test method: 《FZ / T 50002-2013 Test method for irregularity of chemical fibers》;

[0068] Test method for thermal insulation performance: GB / T 35762-2017 Test method for heat transfer properties of textiles;

[0069] Far-infrared testing method: GB / T 30127-2013 Test and evaluation of far-infrared properties of textiles;

[0070] Fabric quality evaluation: Finished product inspection judgment: 〇 - indicates that the fabric surface is flat and smooth; × - indicates that the fabric surface has defects such as pilling, stitch lines, irregular stitches, horizontal stripes, or even holes.

[0071] As can be seen from the above embodiments, in the hollow nylon fiber structure with sheath and core prepared in the embodiments of the present invention, the high-viscosity PA6 core layer can play a supporting role, making the hollow nylon less prone to being crushed; the far-infrared functional masterbatch distributed in the core layer can improve the warmth retention of the hollow nylon, and the PA6 sheath structure also makes the far-infrared functional masterbatch less likely to be exposed, thereby ensuring the quality of yarn and fabric.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hollow nylon fiber with a core and sheath, characterized in that, It comprises a coaxially composite PA6 skin layer and a high-viscosity PA6 core layer, wherein the high-viscosity PA6 core layer has a cavity; the viscosity of the high-viscosity PA6 material in the high-viscosity PA6 core layer is higher than the viscosity of the PA6 material in the PA6 skin layer; and far-infrared functional particles are uniformly distributed in the high-viscosity PA6 core layer. The hollow nylon fiber in the core and sheath has a hollow ratio of 25%-45%; the relative viscosity of the PA6 material in the PA6 sheath is 2.5-2.8; the relative viscosity of the high-viscosity PA6 material in the high-viscosity PA6 core is 3.2-3.7; and the mass ratio of the PA6 sheath to the high-viscosity PA6 core is 1:9 to 3:

7.

2. The hollow nylon fiber with core and sheath according to claim 1, characterized in that, The hollow nylon fibers in the core have a circular or elliptical cross-section.

3. The hollow nylon fiber with core and sheath according to any one of claims 1-2, characterized in that, The far-infrared functional particles contain graphene powder; the graphene powder accounts for 0.1wt% to 0.5wt% of the fiber mass.

4. A method for preparing the core-sheath hollow nylon fiber according to claim 1, characterized in that, Includes the following steps: PA6 chips of ordinary viscosity are fed into the first screw of a twin-screw extruder for melt extrusion to obtain a skin layer spinning melt; high-viscosity PA6 chips and far-infrared functional masterbatch are blended and fed into the second screw of the twin-screw extruder for melt extrusion to obtain a core layer spinning melt; the temperature of melt extrusion in the first screw is lower than the temperature of melt extrusion in the second screw; The sheath spinning melt and the core spinning melt are spun through a sheath-core type composite spinning assembly, using different hollow composite spinnerets to adjust the hollowness of the fibers, to obtain sheath-core hollow nylon fibers with a cavity in the core layer.

5. The preparation method according to claim 4, characterized in that, The PA6 chips of ordinary viscosity, the PA6 chips of high viscosity, and the far-infrared functional masterbatch are all dried raw materials; the moisture content of the dried PA6 chips of ordinary viscosity and the dried PA6 chips of high viscosity is less than 50 ppm.

6. The preparation method according to claim 5, characterized in that, The melt extrusion temperature in the first screw is 260-273℃; the melt extrusion temperature in the second screw is 275-290℃. The core-sheath composite spinning assembly has a sheath spinning temperature of 260-273℃ and a core spinning temperature of 275-290℃; the total spinning speed is 1500-3000 m / min; and the draw ratio of the hollow nylon fiber in the core-sheath structure is 3-5.

7. A fabric, characterized in that, It comprises: hollow nylon fiber with core and sheath as described in any one of claims 1-3 or hollow nylon fiber with core and sheath obtained by the preparation method described in any one of claims 4-6.

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