High-strength flame-retardant aramid fiber and biomass fiber blended yarn and preparation method thereof

Abstract

The invention discloses a high-strength flame-retardant aramid fiber and biomass fiber blended yarn and a preparation method thereof, and relates to the field of functional textile materials.The preparation method comprises the steps that S1, aramid short fibers are subjected to in-situ silicon dioxide implantation pretreatment; s2, preparing aramid card slivers and biomass short fiber card slivers; s3, the aramid fiber card slivers and the biomass short fiber card slivers are mixed and drawn, the aramid fiber filaments and the outer wrapping fiber slivers are converged, covering yarn is formed through a twisting device and collected through a spun yarn guide hook, and blended yarn is obtained. Through modification of the aramid short fibers and combination of core-spun yarn structure cooperation of the core layer aramid filaments, the outer wrapping layer aramid short fibers and the biomass short fibers, the spinnability is greatly improved, the end breakage rate is reduced, the bottleneck that strength and comfort of traditional blended yarn are difficult to consider at the same time is broken through, and synergistic interaction of the flame retardant performance is achieved; and the yarn can still maintain a stable protection function in an extreme environment, so that high strength, flame retardance and skin-friendly comfort are considered, and the application scene of the functional blended yarn is widened.

Description

Technical Field

[0001] This invention relates to the field of functional textile materials technology, and in particular to a high-strength flame-retardant aramid fiber and biomass fiber blended yarn and its preparation method. Background Technology

[0002] Aramid, short for polyphenylene phthalate, possesses excellent properties such as ultra-high strength, high modulus, high temperature resistance, acid and alkali resistance, and light weight. In the field of personal protective equipment, aramid can be made into bulletproof vests, bulletproof helmets, bulletproof armor, fire suits, fire masks, military and police training uniforms, and cut-resistant gloves. In the civilian field, aramid can be made into flame-retardant interior trim and fabrics for aircraft, automobiles, and high-speed trains, and can be made into fire blankets, escape ropes, flame-retardant curtains, bedspreads, pajamas, tablecloths, aprons, and microwave oven gloves. However, pure aramid yarn is expensive, has high fiber rigidity, a stiff hand feel, poor fiber cohesion, is prone to static electricity, has complex pure spinning processing, high production costs, poor moisture absorption (moisture regain <4.5%), and poor wearing comfort. These and other problems greatly affect the application and promotion of aramid fibers.

[0003] Blending aramid fibers with cost-effective, spinnable, and wearable biomass fiber materials (such as cotton, linen, silk, and wool) can not only reduce production costs and improve yarn spinnability, but also allow for adjustments to the blending ratio based on product requirements for flame retardancy and heat resistance. This enables the fibers to complement each other in the blended fabric, thereby increasing the added value of the product.

[0004] However, when aramid is blended with biomass fibers, the significant differences in fiber properties (such as modulus, length, and coefficient of friction) can easily lead to problems such as decreased yarn strength and high yarn breakage rate. These issues severely affect the quality and production efficiency of blended composite yarns in actual production. Therefore, under current technological conditions, the blending of aramid and biomass fibers often fails to achieve ideal spinning results and cannot meet the requirements of high-quality production.

[0005] Therefore, it is necessary to improve upon the shortcomings of existing technologies in order to solve the above problems. Summary of the Invention

[0006] This invention overcomes the shortcomings of the prior art and provides a high-strength flame-retardant aramid fiber and biomass fiber blended yarn and its preparation method. It aims to solve the problems of loose fibers, poor spinnability and poor wearability of conventional aramid yarn, while also having excellent flame retardancy, strength and skin-friendly comfort.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a method for preparing a blended yarn of high-strength flame-retardant aramid fiber and biomass fiber, comprising the following steps:

[0008] S1. Aramid short fibers are immersed in a silane coupling agent solution and stirred at a certain temperature. After treatment, they are placed in an ammonia-ethanol solution containing tetraethyl orthosilicate for polycondensation reaction. After washing and drying, aramid / silica hybrid fibers are obtained.

[0009] S2. The aramid short fibers and biomass short fibers pretreated in step S1 are opened, combed, and drawn to obtain aramid sliver and biomass short fiber sliver, respectively.

[0010] S3. The aramid sliver and biomass short fiber sliver are blended and fed into the drafting device of the spinning frame through the traction roller. The aramid filament is fed in from the back side of the front roller nip and merged with the outer sliver. The core-spun yarn is formed by the twisting device and collected by the spinning guide hook to obtain the blended yarn.

[0011] In a preferred embodiment of the present invention, in step S1, the aramid short fiber is one of para-aramid, meta-aramid, and heterocyclic aramid, and the length of the aramid short fiber is 25-50 mm and the fineness is 1-2.5 dtex.

[0012] In a preferred embodiment of the present invention, in step S1, the silane coupling agent is one of KH550, KH560, KH570, and KH792, with a concentration of 2-10%, and the solvent is dimethyl sulfoxide and water in a mass ratio of 1:1.

[0013] In a preferred embodiment of the present invention, in step S1, the stirring treatment temperature is 80-100°C and the time is 1-1.5 h; the concentration of tetraethyl orthosilicate in the polycondensation reaction tank is 1-5%, the concentration of ammonia is 1-5%, the ratio of water to ethanol is 1:1, the polycondensation reaction temperature is 25-50°C and the time is 2-10 h; the drying temperature is 100-110°C and the time is 10-30 min.

[0014] In a preferred embodiment of the present invention, in step S2, the biomass short fiber is one of cotton fiber, hemp fiber, silk fiber, wool fiber, viscose fiber, lyocell fiber, bamboo fiber, bamboo pulp fiber, seaweed fiber, protein fiber, polylactic acid fiber, and chitin fiber; the biomass short fiber has a length of 10-60 mm and a fineness of 1-10 dtex.

[0015] In a preferred embodiment of the present invention, in step S3, the weight of the outer sliver after blending is 4-7 g / 10m, and the aramid content in the roving is 30-70%.

[0016] In a preferred embodiment of the present invention, in step S3, the draft ratio of the spinning machine is 20 to 40, the core-spun yarn has a Z-twist direction, a twist of 400 to 600 T / m, and a machine speed of 7000 to 10000 r / min.

[0017] In a preferred embodiment of the present invention, in step S3, the aramid filament is one of para-aramid, meta-aramid, or heterocyclic aramid, and the fineness of the aramid filament is 50-110D.

[0018] In a preferred embodiment of the present invention, in step S3, the yarn weight of the blended yarn is 20-50 tex, wherein the core yarn accounts for 20-50% and the overall fiber aramid accounts for 40-90%.

[0019] This invention provides a high-strength flame-retardant aramid fiber and biomass fiber blended yarn, which is prepared by any one of the above methods. The blended yarn includes aramid filaments in the core layer and aramid staple fibers and biomass staple fibers that are twisted together on the core layer.

[0020] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0021] (1) This invention provides a high-strength flame-retardant aramid fiber and biomass fiber blended yarn and its preparation method. By modifying aramid short fibers and combining the core layer aramid filament with the outer layer aramid short fiber and biomass short fiber core-spun yarn structure, the problem caused by the performance difference between aramid and biomass fibers is effectively improved, the spinnability is greatly improved and the breakage rate is reduced. By using the composite structure of filament as core and short fiber blended covering, the high strength characteristics of aramid are retained, while the moisture absorption and breathability of the yarn are optimized by biomass fiber, breaking through the bottleneck of traditional blended yarn where strength and comfort are difficult to balance. Furthermore, by combining specific aramid and biomass fibers, the synergistic effect of flame retardant performance is achieved, so that the yarn can still maintain stable protective function in extreme environments. Thus, high strength, flame retardancy and skin-friendly comfort are taken into account, and the application scenarios of functional blended yarn are broadened.

[0022] (2) In this invention, the in-situ silica implantation pretreatment of aramid short fibers utilizes silane coupling agents to construct active reaction sites on the fiber surface, inducing the hydrolysis and condensation of tetraethyl orthosilicate to form a nanoscale silica composite layer, which significantly improves the surface roughness and polarity of aramid short fibers, enhances the interfacial bonding between aramid short fibers and biomass short fibers, effectively overcomes the cohesion defect caused by the excessively high modulus of aramid fibers, and thus, in spinning, makes the sliver structure more compact and uniform, improving its stability. This not only improves the strength and evenness of blended yarn, but also solves the problem of frequent yarn breakage in traditional spinning processes, significantly reducing the yarn breakage rate.

[0023] (3) By precisely controlling the twist of the core-spun yarn in this invention, the radial clamping force generated by a specific twist angle can be used to address the differences in characteristics between aramid filaments and biomass staple fibers. This allows the aramid filaments, aramid staple fibers, and biomass staple fibers to intertwine with a reasonable degree of tightness, effectively overcoming the defect of weak interfacial bonding between high-modulus aramid and flexible biomass fibers. This balances the internal stress of the fibers, avoiding structural instability such as fiber slippage and core filament exposure caused by excessively low twist, and also avoiding the problems of yarn stiffness and internal stress concentration caused by high twist. This results in improved strength, uniformity, and spinnability of the blended yarn. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the cross-sectional structure of the blended yarn according to a preferred embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the side structure of the blended yarn according to a preferred embodiment of the present invention;

[0027] In the diagram: 1. Aramid filament; 2. Aramid staple fiber; 3. Biomass staple fiber. Detailed Implementation

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0030] It should be noted that the raw materials, equipment and reagents used in this invention can all be purchased from the market or obtained through existing preparation methods.

[0031] A method for preparing a high-strength flame-retardant aramid fiber and biomass fiber blended yarn includes the following steps:

[0032] S1. Aramid short fibers are immersed in a silane coupling agent solution and stirred at a certain temperature. After treatment, they are placed in an ammonia-ethanol solution containing tetraethyl orthosilicate for polycondensation reaction. After washing and drying, aramid / silica hybrid fibers are obtained.

[0033] S2. The aramid short fibers and biomass short fibers pretreated in step S1 are opened, combed, and drawn to obtain aramid sliver and biomass short fiber sliver, respectively.

[0034] S3. The aramid sliver and biomass short fiber sliver are blended and fed into the drafting device of the spinning frame through the traction roller. The aramid filament is fed in from the back side of the front roller nip and merged with the outer sliver. The core-spun yarn is formed by the twisting device and collected by the spinning guide hook to obtain the blended yarn.

[0035] In some specific embodiments, in step S1, the aramid short fiber is one of para-aramid, meta-aramid, or heterocyclic aramid, and the length of the aramid short fiber is 25-50 mm and the fineness is 1-2.5 dtex.

[0036] In some specific embodiments, in step S1, the silane coupling agent is one of KH550, KH560, KH570, and KH792, with a concentration of 2-10%, and the solvent is dimethyl sulfoxide and water in a mass ratio of 1:1.

[0037] In some specific embodiments, in step S1, the stirring temperature is 80-100°C and the time is 1-1.5 h; the concentration of tetraethyl orthosilicate in the polycondensation reaction tank is 1-5%, the concentration of ammonia is 1-5%, the ratio of water to ethanol is 1:1, the polycondensation reaction temperature is 25-50°C and the time is 2-10 h; the drying temperature is 100-110°C and the time is 10-30 min.

[0038] In some specific embodiments, in step S2, the biomass short fiber is one of cotton fiber, hemp fiber, silk fiber, wool fiber, viscose fiber, lyocell fiber, bamboo fiber, bamboo pulp fiber, seaweed fiber, protein fiber, polylactic acid fiber, and chitin fiber; the biomass short fiber has a length of 10-60 mm and a fineness of 1-10 dtex.

[0039] In some specific embodiments, in step S3, the weight of the outer sliver after blending is 4-7 g / 10m, and the aramid content in the roving is 30-70%.

[0040] In some specific implementations, in step S3, the draft ratio of the spinning machine is 20 to 40, the twist direction of the core-spun yarn is Z-twist, the twist is 400 to 600 T / m, and the machine speed is 7000 to 10000 r / min.

[0041] In some specific embodiments, in step S3, the aramid filament is one of para-aramid, meta-aramid, or heterocyclic aramid, and the fineness of the aramid filament is 50-110D.

[0042] In some specific implementations, in step S3, the yarn weight of the blended yarn is 20-50 tex, of which the core yarn accounts for 20-50% and the overall fiber aramid accounts for 40-90%.

[0043] like Figure 1 and Figure 2 As shown, the present invention provides a high-strength flame-retardant aramid fiber and biomass fiber blended yarn, which is prepared by any of the above preparation methods. The blended yarn includes aramid filament 1 in the core layer, and aramid staple fiber 2 and biomass staple fiber 3 twisted together on the core layer.

[0044] To further simplify and make the objectives and effects of the present invention easier to understand, the present invention will be further illustrated in conjunction with the following specific embodiments and comparative examples.

[0045] It should be noted that the raw materials used in the examples and comparative examples are as follows: KH550: purity ≥99%, molecular weight 221.4, CAS number 919-30-2, purchased from Guangzhou Yinuo Chemical Co., Ltd.; tetraethyl orthosilicate: purity ≥99%, density 0.934 g / cm³. 3 The molecular weight is 208.3, CAS number 78-10-4, and it was purchased from Shandong Yuanjin New Materials.

[0046] Example 1

[0047] A method for preparing a high-strength flame-retardant aramid fiber and biomass fiber blended yarn includes the following steps:

[0048] S1. The cleaned para-aramid short fibers were immersed in a 3% KH550 solution, with the solvent being dimethyl sulfoxide and water in a mass ratio of 1:1. The solution was stirred at 90°C for 1 hour. After treatment, the fibers were placed in an ammonia-ethanol solution containing tetraethyl orthosilicate, with a tetraethyl orthosilicate concentration of 3%, an ammonia concentration of 2%, and a water-ethanol ratio of 1:1. The fibers were hydrolyzed at 45°C for 5 hours, washed, and dried at 110°C for 20 minutes to obtain aramid / silica hybrid fibers.

[0049] S2. The para-aramid staple fiber and cotton staple fiber pretreated in step S1 are opened, carded and drawn to obtain para-aramid sliver and cotton staple fiber sliver, respectively.

[0050] S3. After blending para-aramid sliver and cotton staple fiber sliver, an outer sliver with a basis weight of 6.2 g / 10 m is obtained, wherein the ratio of para-aramid to cotton fiber is 5:5. The outer sliver is then fed into the drafting device of the spinning machine through the traction roller. The para-aramid filament is fed in from the back side of the front roller nip and merges with the outer sliver. The drafting ratio of the spinning machine is 30, and the machine speed is 8500 r / min. A Z-twist core-spun yarn with a twist of 520 T / m is formed using the twisting device. The yarn is collected onto the bobbin through the spinning guide hook to obtain a blended yarn with a basis weight of 30.5 tex, a core yarn ratio of 35%, and an overall fiber aramid content of 63%.

[0051] Among them, the length of para-aramid staple fiber is 37mm and the fineness is 1.5dtex; the length of cotton staple fiber is 25mm and the fineness is 1.65dtex; and the fineness of para-aramid filament is 110D.

[0052] Example 2

[0053] This implementation method is basically the same as Example 1, except that the raw materials are different, and the biomass short fiber is flax fiber.

[0054] Example 3

[0055] This implementation method is basically the same as Example 1, except that the raw materials are different, and the biomass short fiber is seaweed fiber.

[0056] Example 4

[0057] This embodiment is basically the same as Example 1, except that the raw materials are different, and the aramid staple fiber and aramid filament are meta-aramid.

[0058] Example 5

[0059] This embodiment is basically the same as Example 1, except that the raw materials are different. The aramid staple fiber and aramid filament are meta-aramid, and the biomass staple fiber is flax fiber.

[0060] Example 6

[0061] This embodiment is basically the same as Example 1, except that the raw materials are different. The aramid staple fiber and aramid filament are meta-aramid, and the biomass staple fiber is seaweed fiber.

[0062] Example 7

[0063] This embodiment is basically the same as Example 1, except that the raw materials are different, and the aramid short fibers and aramid filaments are heterocyclic aramids.

[0064] Example 8

[0065] This embodiment is basically the same as Example 1, except that the raw materials are different. The aramid short fiber and aramid filament are heterocyclic aramid, and the biomass short fiber is flax fiber.

[0066] Example 9

[0067] This embodiment is basically the same as Example 1, except that the raw materials are different. The aramid short fiber and aramid filament are heterocyclic aramid, and the biomass short fiber is seaweed fiber.

[0068] Performance testing: The blended yarns obtained in Examples 1-9 were tested for yarn breakage rate, flame retardant properties, strength properties and yarn evenness in sequence. The results are shown in Table 1.

[0069] Spinning breakage rate: Under the blended yarn condition of the spinning machine, the total number of spindles and the number of breakages of a single spinning machine are continuously recorded within 8 hours. The breakage rate is calculated as follows: Breakage rate (times / thousand spindle hours) = (total breakages × 1000) / (total number of spindles × time (h)). The test is repeated for 3 cycles (3 days), and the average value is taken as the final result.

[0070] Flame retardant performance: Refer to GB / T 5454-1997 "Determination of oxygen index of burning performance of textiles", and take the average value of 5 tests as the limiting oxygen index result.

[0071] Strength performance: Refer to GB / T 3916-2013 "Determination of breaking strength and elongation at break of single yarn in packaged textiles (CRE method)", record the breaking strength and elongation at break, and take the average of 5 tests as the final result.

[0072] Evenness performance: Refer to GB / T 3292.1-2008 "Textiles - Test methods for unevenness of yarn - Part 1: Capacitance method", and take the average value of 5 tests as the final result of evenness CV value (coefficient of variation).

[0073] Table 1: Performance test results of blended yarns from Examples 1-9

[0074]

[0075] As shown in Table 1:

[0076] Example 6 uses meta-aramid as the core layer and outer short fibers, combined with seaweed fiber, which exhibits the best performance, achieving low breakage rate, high flame retardancy, and excellent evenness, while also possessing superior strength properties. Specifically, the meta-aramid molecular chain contains a meta-benzene ring structure, and when heated, the molecular chain has a large free volume, which can soften and expand at 275°C to form a dense foam carbon layer, while simultaneously decomposing and releasing non-flammable gases to dilute oxygen. Seaweed fiber, on the other hand, releases natural calcium when it decomposes at around 300°C. 2+ / Mg 2+It is transformed into CaO / MgO metal oxide, which can catalyze the dehydration and carbonization of meta-aramid to make the carbon layer more compact, and neutralize H· / OH· free radicals in the flame. The nanoporous aerogel layer generated by its combustion can also adsorb combustible gases and improve heat insulation. Compared with other aramid and biomass fibers, meta-aramid and seaweed fiber are highly compatible, forming a synergistic flame retardant effect of "chemical catalysis + physical barrier" to achieve a high flame retardant effect of limiting oxygen index of 42.1%.

[0077] Furthermore, the surface roughness and polarity of meta-aramid staple fibers are improved after silica pretreatment, which enhances the interfacial bonding force with seaweed fibers, resulting in a tighter and more uniform fiber arrangement and improved yarn structure stability. As a result, the breaking rate is only 5.6 times / thousand spindles, the breaking strength reaches 612.7 cN, the breaking elongation is 20.5%, and the yarn evenness CV value is 10.3%, achieving the best overall performance.

[0078] To further illustrate the present invention, the optimal embodiment 6 is used as the basis for comparison.

[0079] Comparative Example 1

[0080] This comparative example is basically the same as Example 6, except that meta-aramid short fibers were not added. Specifically, it includes the following steps:

[0081] S1. Seaweed short fibers are opened, combed, and drawn to obtain seaweed short fiber slivers;

[0082] S2. The seaweed short fiber sliver is fed into the drafting device of the spinning frame via the traction roller. The meta-aramid filament is fed in from the back side of the front roller nip and merges with the outer sliver. The drafting ratio of the spinning frame is 30 and the speed is 8500 r / min. The twisting device is used to form Z-twist core-spun yarn with a twist of 520 T / m. The yarn is collected onto the bobbin by the spinning guide hook to obtain a blended yarn with a yarn weight of 30.5 tex and a core yarn ratio of 63%.

[0083] The seaweed short fiber has a length of 25mm and a fineness of 1.65dtex; the meta-aramid filament has a fineness of 110D.

[0084] Comparative Example 2

[0085] This comparative example is basically the same as Example 6, except that the meta-aramid short fibers are not modified, and step S2 is specifically: the meta-aramid short fibers and seaweed short fibers are opened, combed and drawn to obtain meta-aramid sliver and seaweed short fiber sliver, respectively.

[0086] Comparative Example 3

[0087] This comparative example is basically the same as Example 6, except that the twist of the spinning machine is different. Specifically, step S3 is as follows: after mixing meta-aramid sliver and seaweed short fiber sliver, an outer sliver with a basis weight of 6.2 g / 10 m is obtained, in which the ratio of meta-aramid to seaweed fiber is 5:5. The outer sliver is then fed into the drafting device of the spinning machine through the traction roller. The meta-aramid filament is fed in from the back side of the front roller nip and merges with the outer sliver. The drafting ratio of the spinning machine is 30 and the machine speed is 8500 r / min. A Z-twist core-spun yarn with a twist of 400 T / m is formed using the twisting device. The yarn is collected onto the bobbin through the spinning guide hook to obtain a blended yarn with a basis weight of 30.5 tex, a core yarn ratio of 35%, and an overall fiber aramid content of 63%.

[0088] Comparative Example 4

[0089] This comparative example is basically the same as Example 6, except that the twist of the spinning machine is different. Specifically, step S3 is as follows: after mixing meta-aramid sliver and seaweed short fiber sliver, an outer sliver with a basis weight of 6.2 g / 10 m is obtained, in which the ratio of meta-aramid to seaweed fiber is 5:5. The outer sliver is then fed into the drafting device of the spinning machine through the traction roller. The meta-aramid filament is fed in from the back side of the front roller nip and merges with the outer sliver. The drafting ratio of the spinning machine is 30 and the machine speed is 8500 r / min. A Z-twist core-spun yarn with a twist of 380 T / m is formed using the twisting device. The yarn is collected onto the bobbin through the spinning guide hook to obtain a blended yarn with a basis weight of 30.5 tex, a core yarn ratio of 35%, and an overall fiber aramid content of 63%.

[0090] Comparative Example 5

[0091] This comparative example is basically the same as Example 6, except that the twist of the spinning machine is different. Specifically, step S3 is as follows: after mixing meta-aramid sliver and seaweed short fiber sliver, an outer sliver with a basis weight of 6.2 g / 10 m is obtained, in which the ratio of meta-aramid to seaweed fiber is 5:5. The outer sliver is then fed into the drafting device of the spinning machine through the traction roller. The meta-aramid filament is fed in from the back side of the front roller nip and merges with the outer sliver. The drafting ratio of the spinning machine is 30 and the machine speed is 8500 r / min. A Z-twist core-spun yarn with a twist of 600 T / m is formed using the twisting device. The yarn is collected onto the bobbin through the spinning guide hook to obtain a blended yarn with a basis weight of 30.5 tex, a core yarn ratio of 35%, and an overall fiber aramid content of 63%.

[0092] Comparative Example 6

[0093] This comparative example is basically the same as Example 6, except that the twist of the spinning machine is different. Specifically, step S3 is as follows: after mixing meta-aramid sliver and seaweed short fiber sliver, an outer sliver with a basis weight of 6.2 g / 10 m is obtained, in which the ratio of meta-aramid to seaweed fiber is 5:5. The outer sliver is then fed into the drafting device of the spinning machine through the traction roller. The meta-aramid filament is fed in from the back side of the front roller nip and merges with the outer sliver. The drafting ratio of the spinning machine is 30 and the machine speed is 8500 r / min. A Z-twist core-spun yarn with a twist of 610 T / m is formed using the twisting device. The yarn is collected onto the bobbin through the spinning guide hook to obtain a blended yarn with a basis weight of 30.5 tex, a core yarn ratio of 35%, and an overall fiber aramid content of 63%.

[0094] Performance testing: The blended yarns obtained in Comparative Examples 1-6 were tested for yarn breakage rate, flame retardant properties, strength properties and yarn evenness in the same manner as the blended yarns obtained in Examples 1-9. The results were compared with those of Example 6 and are shown in Table 2.

[0095] Table 2: Performance test results of blended yarns from Comparative Examples 1-6

[0096]

[0097] As shown in Table 2:

[0098] A comparison of Example 6 and Comparative Example 1 reveals that: Comparative Example 1 did not add meta-aramid staple fibers, and the outer sheath only contained seaweed fibers. Due to the lack of surface roughness and polarity enhancement characteristics of the meta-aramid staple fibers after pretreatment, the interfacial bonding force between the seaweed fibers and the core layer meta-aramid filaments was weak, and the fibers were loose and prone to slippage, resulting in a sharp increase in the breakage rate to 17.4 times / thousand spindles. At the same time, the synergistic effect of meta-aramid staple fibers on flame retardancy disappeared, and only the basic flame retardant method of the core layer meta-aramid filaments was used to form a dense char layer, reducing the flame retardant performance to 21.4%. Insufficient fiber cohesion also led to a loose yarn structure, with a breaking strength of only 328.2 cN, a breaking elongation of 11.7%, and a yarn evenness CV value deteriorating to 20.4%.

[0099] A comparison of Example 6 and Comparative Example 2 reveals that: unmodified meta-aramid staple fibers have a smooth surface and low polarity, resulting in weak interfacial bonding with seaweed fibers and easy slippage and separation between fibers, leading to a breakage rate of 14.2 times / 1000 spindles; poor interfacial bonding reduces yarn structural stability, with breaking strength decreasing to 494.1 cN, breaking elongation at break at 14.2%, and yarn evenness CV value at 16.7%; simultaneously, the unmodified meta-aramid staple fiber surface lacks nano-silica particles, failing to enhance the friction coefficient with seaweed fibers, weakening the flame retardant synergistic effect, and reducing the limiting oxygen index to 34.8%.

[0100] A comparison of Example 6 with Comparative Examples 3-4 reveals that: in Comparative Example 3, at a lower twist, slippage easily occurs between the aramid filament and the outer fibers, leading to localized exposure of the yarn core and a decrease in breaking strength to 552.4 cN (a loss of 9.8%). In contrast, the excessively low twist in Comparative Example 4 results in insufficient tightness of the helical arrangement between fibers, weak cohesion, and easy fiber slippage. When the breakage rate increases to 12.4 times / thousand spindles, the evenness CV value deteriorates to 17.3%.

[0101] A comparison of Example 6 with Comparative Examples 5-6 reveals that: Comparative Example 5, at a higher twist, caused excessive compression of the outer fibers, resulting in damage to the seaweed fiber crystal structure and a decrease in elongation at break to 18.1% (a loss of 11.7%). Although the increased twist temporarily enhanced the cohesion (breaking strength 574.6 cN), the concentration of internal stress led to yarn stiffness. In contrast, the excessively high twist in Comparative Example 6 caused internal stress concentration due to excessive spiral twisting, resulting in yarn stiffness and an increased risk of fiber molecular chain breakage, leading to some microcracks. During combustion, these cracks accelerated oxygen diffusion, causing the limiting oxygen index to drop to 32.3%.

[0102] The above description is based on the preferred embodiments of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the invention is defined by the appended claims rather than the foregoing description, and all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0103] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a high-strength flame-retardant aramid fiber and biomass fiber blended yarn, characterized in that, Includes the following steps: S1. Aramid short fibers are immersed in a silane coupling agent solution and stirred at a certain temperature. After treatment, they are placed in an ammonia-ethanol solution containing tetraethyl orthosilicate for polycondensation reaction. After washing and drying, aramid / silica hybrid fibers are obtained. S2. The aramid short fibers and biomass short fibers pretreated in step S1 are opened, combed, and drawn to obtain aramid sliver and biomass short fiber sliver, respectively. S3. The aramid sliver and biomass short fiber sliver are blended and fed into the drafting device of the spinning frame through the traction roller. The aramid filament is fed in from the back side of the front roller nip and merged with the outer sliver. The core-spun yarn is formed by the twisting device and collected by the spinning guide hook to obtain the blended yarn.

2. The method for preparing a high-strength flame-retardant aramid fiber and biomass fiber blended yarn according to claim 1, characterized in that: In step S1, the aramid short fiber is one of para-aramid, meta-aramid, or heterocyclic aramid, and the length of the aramid short fiber is 25-50 mm and the fineness is 1-2.5 dtex.

3. The method for preparing a high-strength flame-retardant aramid fiber and biomass fiber blended yarn according to claim 1, characterized in that: In step S1, the silane coupling agent is one of KH550, KH560, KH570, and KH792, with a concentration of 2-10%, and the solvent is dimethyl sulfoxide and water in a mass ratio of 1:

1.

4. The method for preparing a high-strength flame-retardant aramid fiber and biomass fiber blended yarn according to claim 1, characterized in that: In step S1, the stirring treatment is carried out at a temperature of 80–100°C for 1–1.5 h; the concentration of tetraethyl orthosilicate in the polycondensation reaction tank is 1–5%, the concentration of ammonia is 1–5%, the ratio of water to ethanol is 1:1, the polycondensation reaction temperature is 25–50°C for 2–10 h; and the drying temperature is 100–110°C for 10–30 min.

5. The method for preparing a high-strength flame-retardant aramid fiber and biomass fiber blended yarn according to claim 1, characterized in that: In step S2, the biomass short fiber is one of cotton fiber, hemp fiber, silk fiber, wool fiber, viscose fiber, lyocell fiber, bamboo fiber, bamboo pulp fiber, seaweed fiber, protein fiber, polylactic acid fiber, and chitin fiber; the biomass short fiber has a length of 10-60 mm and a fineness of 1-10 dtex.

6. The method for preparing a high-strength flame-retardant aramid fiber and biomass fiber blended yarn according to claim 1, characterized in that: In step S3, the weight of the outer sliver after blending is 4-7 g / 10m, and the aramid content in the roving is 30-70%.

7. The method for preparing a high-strength flame-retardant aramid fiber and biomass fiber blended yarn according to claim 1, characterized in that: In step S3, the draft ratio of the spinning machine is 20 to 40, the twist direction of the core-spun yarn is Z-twist, the twist is 400 to 600 T / m, and the machine speed is 7000 to 10000 r / min.

8. The method for preparing a high-strength flame-retardant aramid fiber and biomass fiber blended yarn according to claim 1, characterized in that: In step S3, the aramid filament is one of para-aramid, meta-aramid, or heterocyclic aramid, and the fineness of the aramid filament is 50-110D.

9. The method for preparing a high-strength flame-retardant aramid fiber and biomass fiber blended yarn according to claim 1, characterized in that: In step S3, the yarn weight of the blended yarn is 20-50 tex, of which the core yarn accounts for 20-50% and the overall fiber aramid accounts for 40-90%.

10. A high-strength flame-retardant aramid fiber and biomass fiber blended yarn, characterized in that, The blended yarn, prepared by any one of claims 1-9, comprises an aramid filament core layer and aramid staple fibers and biomass staple fibers twisted together on the core layer.

Images