Ultra-light warm-keeping nylon 6 pre-oriented yarn and production method thereof

Abstract

The invention discloses an ultralight warm-keeping nylon 6 pre-oriented yarn and a production method thereof, and belongs to the technical field of chemical fiber production. Nylon 6 slices are melted and then extruded to obtain nylon 6 melt, the nylon 6 melt enters a spinning assembly and is sprayed out through a spinneret plate to form tows, then monomer suction, side blowing cooling, bundling oiling, stretching sizing and network interlacing are carried out, finally winding forming is carried out, and the ultra-light warm-keeping nylon 6 pre-oriented yarn is obtained. The cross section of each spinneret micropore is of an S-shaped structure, each S-shaped structure comprises three vertical grooves and two horizontal grooves, every two adjacent vertical grooves are connected through one horizontal groove, one horizontal groove is connected with the head end of the corresponding vertical groove, and the other horizontal groove is connected with the tail end of the corresponding vertical groove. The fiber cross section of the nylon 6 pre-oriented yarn is in an 8-shaped double-hollow shape, and the nylon 6 pre-oriented yarn has the advantages of being low in heat conductivity coefficient, light in weight, stable in structure and not prone to deformation, and can endow fibers with good heat retention property and comfort.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical fiber production, and particularly relates to an ultra-light and warm-keeping nylon 6 pre-oriented yarn and a production method thereof. Background Art

[0002] With rising consumer spending, demand for cold-weather clothing has shifted from simply pursuing "warmth" to a comprehensive focus on "lightweight, comfort, and aesthetics." Traditional thermal insulation materials rely on thickened filling layers for insulation, resulting in bulky and heavy garments that severely restrict the wearer's mobility and compromise their aesthetics. Modern consumers are placing higher demands on winter clothing: while ensuring excellent thermal insulation, they must also offer a lightweight feel, good breathability, and fashionable designs. This market demand is driving the textile industry to accelerate the development of a new generation of high-performance thermal fibers, requiring not only breakthroughs in the physical limitations of traditional materials but also technological innovations at the molecular level to meet the product demands of "highly effective warmth, extreme lightness, and lasting comfort."

[0003] In the field of chemical fibers, the mainstream technologies for improving fiber thermal insulation focus on two main areas: one is to lock in stagnant air through special-shaped cross-section designs, using the low thermal conductivity of air to block heat loss; the other is to add functional materials to enhance heat reflection efficiency. However, existing technologies have significant flaws: ordinary hollow fibers are prone to collapse due to insufficient structural strength, resulting in a decrease in thermal insulation performance; while adding inorganic particles can improve thermal insulation, it tends to increase fiber density, reduce softness, and may cause skin discomfort. Especially for high-strength and wear-resistant materials such as nylon 6, their melt properties make it more difficult to stably form complex hollow structures. Conventional circular spinnerets can only produce solid or single-hole fibers, making it difficult to achieve both lightweight and structural stability. This has become a key bottleneck restricting the development of high-performance nylon thermal insulation fibers.

[0004] As an important synthetic fiber raw material, nylon 6 has advantages such as high strength, good resilience, wear resistance and corrosion resistance. However, it has not made any breakthroughs in the field of thermal insulation applications for a long time. The core contradiction lies in the mutual exclusion between lightweight hollow structure and mechanical properties. When using traditional spinning technology to prepare hollow nylon 6 fibers, there are three major technical obstacles. First, the structural stability is poor. During the melt cooling process, surface tension can easily cause the hollow cavity to shrink and deform, or even fail to close. Secondly, the process control is sensitive. Even slight fluctuations in spinning pressure and cooling conditions can cause cross-sectional morphological distortion, making product uniformity difficult to guarantee. Finally, it is difficult to balance performance. Although excessive expansion of the hollowness improves thermal insulation, it significantly weakens the fiber's breaking strength and fatigue resistance.

[0005] The mainstream thermal insulation materials currently on the market all have inherent shortcomings. Natural down easily absorbs moisture, becomes compacted, and is expensive; polyester hollow fibers have limited thermal insulation efficiency and are prone to pilling; and acrylic fibers, while light and warm, have low strength and are prone to static electricity. In contrast, if nylon 6 can achieve breakthroughs in hollow structure molding technology, it will fully leverage its inherent advantages of light weight, high strength, and good moisture absorption and vapor permeability. However, existing patents and literature show that conventional spinning equipment and spinneret designs can only produce single-hole hollow fibers for nylon 6, which have low air retention and easily flattened structures, making it difficult to meet the requirements of ultra-light and high thermal insulation. More critically, the lack of a coordinated control scheme for spinning pressure, cooling airflow, and spinneret hole shape results in poor controllability of fiber cross-sectional morphology, directly restricting the industrial reproducibility of product performance.

[0006] A Chinese patent with publication number CN120138831A and application date of May 15, 2025, discloses a method for preparing nylon 6 fiber with thermal insulation properties, wherein the heat-storage PA6 masterbatch is melt-spinned to prepare the fiber; the heat-storage PA6 masterbatch is obtained by filling a phase change material into a porous structure of a PA6 resin, and the PA6 resin is obtained by reacting with a porogen. In this application, by filling the porous structure of the PA6 resin with a phase change material, the high-porosity structure encapsulates the phase change material inside the pores, thereby reducing the loss of the phase change material and improving the thermal insulation and durability of the prepared fiber. However, the preparation process requires multiple steps, first preparing a porous PAG resin, then synthesizing graphene-grafted polyethylene glycol, and finally high-speed stirring and encapsulation. This multi-step process will reduce production efficiency and increase energy consumption. The phase change material itself is also prone to decomposition at high spinning temperatures, which may affect the stability of fiber performance.

[0007] A Chinese patent application with publication number CN118292140A, filed on May 9, 2024, discloses a sheath-core hollow nylon fiber, its preparation method, and fabric. The fiber comprises, in sequence, a coaxially composited PA6 sheath layer 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 the viscosity of the PA6 material in the PA6 sheath layer, and the high-viscosity PA6 core layer is uniformly distributed with far-infrared functional particles. However, this method is limited by the complexity of the structural design. A twin-screw extruder is required to process the sheath and core melts separately, and the temperatures of the two melts must be precisely controlled. This temperature differential control is prone to fluctuations in actual production, potentially resulting in poor bonding between the sheath and core layers. Although the high-viscosity core layer improves compressive strength, the overall fiber feel is stiff, affecting wearing comfort. Furthermore, the far-infrared particles are confined to the core layer, which reduces wear but also limits their thermal radiation efficiency.

[0008] In summary, the development of a nylon 6 hollow fiber preparation process based on a special spinneret micropore configuration and precise spinning parameter control, the realization of stable molding of complex hollow structures through innovative design, and the spinning process without sacrificing mechanical properties, fundamentally solves the contradictory needs of lightweight, high warmth, strength and durability. It not only has significant scientific value, but will also fill the market gap of high-performance nylon thermal insulation fibers and promote the technological upgrading of the cold-proof clothing industry. Summary of the Invention

[0009] In order to solve the problems existing in the prior art, the present invention provides an ultra-light and warm nylon 6 pre-oriented yarn and a production method thereof. The fiber cross-section of the nylon 6 pre-oriented yarn is an 8-shaped double hollow shape, which has the characteristics of low thermal conductivity, light weight, stable structure and not easy to deform, and can give the fiber good warmth retention and comfort.

[0010] The technical solutions of the present invention are as follows:

[0011] One of the purposes of the present invention is to provide a method for producing ultralight and thermal-insulating nylon 6 pre-oriented yarn, comprising the following steps:

[0012] The nylon 6 chips are melted and extruded to obtain a nylon 6 melt, which enters a spinning assembly and is ejected from a spinneret to form a tow. The tow is then subjected to monomer extraction, side-blowing cooling, bundling and oiling, stretching and shaping, and interlacing, and finally winding to obtain the ultra-light and warm nylon 6 pre-oriented yarn.

[0013] The spinneret includes a substrate 1 and 12-34 spinneret micropores 2 located on the substrate, and the cross-section of the spinneret micropores 2 is an S-shaped structure; the S-shaped structure includes three horizontal grooves 2-2, two vertical short grooves 2-1 and two vertical long grooves 2-3; two adjacent horizontal grooves 2-2 are connected by a vertical long groove 2-3, wherein one horizontal groove is connected to the head end of the vertical long groove 2-3, and the other horizontal groove is connected to the tail end of the vertical long groove 2-3; the other ends of the first and last horizontal grooves 2-2 are respectively connected to the vertical short groove 2-1.

[0014] Furthermore, the nylon 6 chips are melted, mixed, compressed and extruded by a screw extruder, and the temperature of the melting zone in the screw extruder is set at 250-260°C.

[0015] Furthermore, the pump pressure of the spinning assembly after being put into operation is 120-150 bar.

[0016] Furthermore, in the side-blowing cooling step, the side-blowing air is directed toward the vertical grooves 2-3 of the spinneret microholes at an angle of 90°.

[0017] Furthermore, the side wind speed is 0.48-0.55m / s.

[0018] Furthermore, the side-blowing cooling temperature is 23° C., and the side-blowing humidity is 75%.

[0019] Furthermore, the winding speed in the winding forming step is 4100-4300 m / min.

[0020] A second object of the present invention is to provide an ultra-light and warm-keeping nylon 6 pre-oriented yarn.

[0021] Furthermore, the fiber cross-section of the ultra-light and warm-keeping nylon 6 pre-oriented yarn is an 8-shaped double hollow cavity.

[0022] Furthermore, the ultra-light thermal insulation nylon 6 pre-oriented yarn has a fineness of 25.23-89.68 dtex, a breaking strength of 3.98-4.41 cN / dtex, an elongation at break of 62.13-66.33%, and a yarn unevenness rate of 0.93-1.33.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention discloses for the first time an ultra-light thermal insulation nylon 6 pre-oriented yarn with an 8-shaped double hollow cross-section designed with S-shaped spinneret micropores. The innovation of this special-shaped cross-section structure breaks through the limitations of traditional thermal insulation fibers. The structure forms an S-shaped flow channel through three vertical grooves and two horizontal grooves, so that double hollow chambers are naturally formed during melt extrusion, which significantly improves the static air retention and effectively reduces its low thermal conductivity. The fiber cross-sectional morphology is precisely cooled and solidified by side blowing to ensure structural stability, with a breaking strength of 3.98-4.41cN / dtex and better compressive deformation resistance than traditional hollow fibers, achieving the unity of physical insulation and lightweight. Compared with the addition of phase change materials or skin-core composite processes, the present invention achieves high thermal insulation with a single nylon 6 material, avoiding the risks of functional particle loss, skin-core delamination, etc.

[0025] 2. The present invention also provides a production method for the ultra-light and warm nylon 6 pre-oriented yarn. The cross-sectional design of traditional nylon 6 fibers easily leads to deterioration of fiber production conditions and physical properties. The present invention first combines the innovation of the spinneret with the optimization of the number of 2 spinneret micropores, utilizes 12-34 S-shaped micropore array designs, and regulates the melt rheological behavior through a combination of horizontal / vertical grooves to directly form an 8-shaped double hollow structure; secondly, combined with side-blown air cooling and directional strengthening, the horizontal grooves of the spinneret holes are blown vertically at 90° to achieve uniform solidification of the yarn bundle; at the same time, the melt temperature and the pressure after the spinning assembly pump are strictly controlled to balance the melt fluidity and crystallinity. The production method achieves the unity of structural stability and mass production economy without the need to add additional additives or composite spinning equipment, and the production efficiency is significantly better than the existing phase change material filled technology.

[0026] 3、The performance index of the ultra-light warm nylon 6 pre-oriented yarn designed in the application meets the following requirements: the breaking strength is 3.92-4.41 cN / dtex, the elongation at break is 62.13-66.33%, and the unevenness is 0.93-1.33. The ultra-light warm nylon 6 pre-oriented yarn has the characteristics of light weight, low thermal conductivity and excellent structure compression resistance, has good warmth retention and comfort, and can be directly used for POY yarn production. After post-processing, it can be used for making light-weight cold-weather clothing, giving the fabric high resilience, not easy to collapse after repeated washing, meeting the needs of human body movement, and solving the problem of bloated traditional multi-layer filled clothing. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The structure diagram of the spinneret used in the production method of the ultra-light warm nylon 6 pre-oriented yarn;

[0028] Figure 2 The cross-sectional structure diagram of the spinning micro-hole of the spinneret used in the production method of the ultra-light warm nylon 6 pre-oriented yarn;

[0029] Figure 3 The enlarged microscopic cross-sectional structure diagram of the ultra-light warm nylon 6 pre-oriented yarn. DETAILED DESCRIPTION

[0030] The application will be further described in conjunction with preferred embodiments, and the endpoints and any values of the scope disclosed in the application are not limited to the exact range or value, and these ranges or values should be understood to include values close to these ranges or values; for numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed herein.

[0031] The experimental methods in the following examples are all conventional methods, and are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions, unless otherwise specified.

[0032] The materials, reagents and the like used in the following examples can be obtained from commercial channels, unless otherwise specified.

[0033] Example 1

[0034] The application provides a production method of an ultra-light warm nylon 6 pre-oriented yarn, which comprises the following steps:

[0035] S1, using a screw extruder to melt, mix, compress and extrude nylon 6 chips, setting the temperature of the melting zone to 250℃, 252℃, 256℃, 258℃, 258℃, and obtaining a nylon 6 melt;

[0036] S2. The nylon 6 melt is accurately metered by a melt metering pump, and then transported to the spinning assembly through a melt pipe for filtration. The pump pressure after the spinning assembly is adjusted to 120 after it is put on the machine;

[0037] S3, spraying out through a spinneret having 12 S-shaped spinneret holes to form a filament bundle;

[0038] S4, cooling the nylon 6 fiber tow with side-blowing air, with the side-blowing air directed toward the vertical grooves 2-3 of the spinneret micropores at an angle of 90°, the side-blowing air cooling temperature being 23° C., the humidity being 75%, and the wind speed being 0.48 m / s;

[0039] S5, after bundling, oiling, stretching, shaping and interlacing, winding at 4100 m / min to obtain the ultra-light and thermal insulation nylon 6 pre-oriented yarn.

[0040] Example 2

[0041] This embodiment provides an ultralight and thermal-insulating nylon 6 pre-oriented yarn, the production method of which includes the following steps:

[0042] S1. Using a screw extruder, nylon 6 chips are melted, mixed, compressed and extruded. The melting zone is set at 250°C, 252°C, 256°C, 258°C and 258°C to obtain a nylon 6 melt.

[0043] S2. The nylon 6 melt is accurately metered by a melt metering pump and then transported to the spinning assembly through a melt pipe for filtration. The pump pressure after the spinning assembly is adjusted to 133 bar after it is put on the machine;

[0044] S3, spraying out through a spinneret having 24 S-shaped spinneret microholes to form a filament bundle;

[0045] S4, cooling the nylon 6 fiber tow with side-blowing air, with the side-blowing air directed toward the vertical grooves 2-3 of the spinneret micropores at an angle of 90°, the side-blowing air cooling temperature being 23° C., the humidity being 75%, and the wind speed being 0.50 m / s;

[0046] S5, after bundling, oiling, stretching, shaping and interlacing, winding at 4200 m / min to obtain the ultra-light and thermal insulation nylon 6 pre-oriented yarn.

[0047] Example 3

[0048] This embodiment provides a method for producing ultralight and thermal-insulating nylon 6 pre-oriented yarn, comprising the following steps:

[0049] S1. Using a screw extruder, nylon 6 chips are melted, mixed, compressed, and extruded. The melting zone is set at 252°C, 254°C, 257°C, 259°C, and 260°C to obtain a nylon 6 melt.

[0050] S2. The nylon 6 melt is accurately metered by a melt metering pump and then transported to the spinning assembly through a melt pipe for filtration. The pump pressure after the spinning assembly is adjusted to 150 bar after it is put on the machine;

[0051] S3, the filaments are ejected through a spinneret having 34 S-shaped spinneret holes to form a filament bundle;

[0052] S4, cooling the nylon 6 fiber tow with side-blowing air, with the side-blowing air directed toward the vertical grooves 2-3 of the spinneret micropores at an angle of 90°, the side-blowing air cooling temperature being 23° C., the humidity being 75%, and the wind speed being 0.55 m / s;

[0053] S5, after bundling, oiling, stretching, shaping and interlacing, winding at 4300 m / min to obtain the ultra-light and thermal insulation nylon 6 pre-oriented yarn.

[0054] Performance Characterization

[0055] 1. The performance of the ultra-light and thermal-insulating nylon 6 pre-oriented yarns described in Examples 1-3 above was characterized by various indicators. The results are shown in Table 1:

[0056] Table 1 Performance test results of ultralight warm nylon 6 pre-oriented yarn

[0057]

[0058] As can be seen from Table 1, the ultralight and warm nylon 6 pre-oriented yarn prepared by the present invention has a fiber thickness of 25.23-89.68 dtex, a breaking strength of 3.98-4.41 cN / dtex, a breaking strength variation coefficient of 2.23-2.69%, a breaking elongation of 62.13-66.33%, a breaking strength variation coefficient of 1.52-2.32%, and a yarn unevenness rate of 0.93-1.33%, maintaining the performance of the nylon 6 pre-oriented yarn.

[0059] In summary, the present invention utilizes ultra-light, thermally insulating nylon 6 pre-oriented yarns produced using S-shaped spinneret micropores. The fiber cross-section exhibits a figure-eight double-hollow cavity structure, resulting in a lightweight, low-deformation structure. This fiber exhibits excellent warmth retention and comfort. After subsequent processing, it can be used to produce winter clothing that offers excellent warmth retention, portability, and comfort. This product has promising market prospects.

[0060] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for producing ultralight and warm nylon 6 pre-oriented yarn, characterized in that: The following steps are involved: The nylon 6 chips are melted and extruded to obtain a nylon 6 melt, which enters a spinning assembly and is ejected from a spinneret to form a tow. The tow is then subjected to monomer extraction, side-blowing cooling, bundling and oiling, stretching and shaping, and interlacing, and finally winding to obtain the ultra-light and warm nylon 6 pre-oriented yarn. The spinneret comprises a substrate (1) and 12-34 spinneret micropores (2) located on the substrate, wherein the cross section of the spinneret micropores (2) is an S-shaped structure; the S-shaped structure comprises three horizontal grooves (2-2), two vertical short grooves (2-1) and two vertical long grooves (2-3); two adjacent horizontal grooves (2-2) are connected by a vertical long groove (2-3), wherein one horizontal groove is connected to the head end of the vertical long groove (2-3), and the other horizontal groove is connected to the tail end of the vertical long groove (2-3); and the other ends of the head and tail horizontal grooves (2-2) are respectively connected to the vertical short groove (2-1).

2. The method for producing ultralight and thermal-insulating nylon 6 pre-oriented yarn according to claim 1, characterized in that: The nylon 6 chips are melted, mixed, compressed and extruded by a screw extruder, and the temperature of the melting zone in the screw extruder is set at 250-260°C.

3. The method for producing ultralight and thermal insulation nylon 6 pre-oriented yarn according to claim 1, characterized in that: The pump pressure of the spinning assembly after being put into the machine is 120-150 bar.

4. The method for producing ultralight and thermal-insulating nylon 6 pre-oriented yarn according to claim 1, characterized in that: In the side-blowing cooling step, the side-blowing air is directed toward the vertical grooves (2-3) of the spinneret microholes at an angle of 90°.

5. The method for producing ultralight and thermal-insulating nylon 6 pre-oriented yarn according to claim 4, characterized in that: The side wind speed is 0.48-0.55m / s.

6. The method for producing ultralight and thermal insulation nylon 6 pre-oriented yarn according to claim 4, characterized in that: The side-blowing cooling temperature is 23° C., and the side-blowing humidity is 75%.

7. The method for producing ultralight and thermal insulation nylon 6 pre-oriented yarn according to claim 1, characterized in that: The winding speed in the winding forming step is 4100-4300 m / min.

8. An ultralight and thermal insulation nylon 6 pre-oriented yarn produced according to the production method according to any one of claims 1 to 7.

9. The ultra-light and warm-keeping nylon 6 pre-oriented yarn according to claim 8, characterized in that: The fiber cross section of the ultralight and warm-keeping nylon 6 pre-oriented yarn is an 8-shaped double hollow cavity.

10. The ultra-light and warm-keeping nylon 6 pre-oriented yarn according to claim 8, characterized in that: The ultralight thermal insulation nylon 6 pre-oriented yarn has a fineness of 25.23-89.68 dtex, a breaking strength of 3.98-4.41 cN / dtex, a breaking elongation of 62.13-66.33%, and a yarn unevenness rate of 0.93-1.33.

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