A blended yarn and a method of making the same

Abstract

The application discloses a blended yarn and a preparation method thereof, and belongs to the technical field of blended yarns. The preparation method of the blended yarn comprises the following steps: uniformly coating an impregnating agent on the surface of modified carbon fibers, and drying to obtain modified carbon fiber filaments; twisting every 1-3 strands of the modified carbon fiber filaments, the twist of the twisting being 80-100 twists / m, and twisting every 3-5 strands of synthetic fiber filaments, the twist of the twisting being 70-90 twists / m; combining the twisted modified carbon fiber filaments and the synthetic fiber filaments, coating the impregnating agent on the surface of the combined yarn, and drying to obtain the blended yarn; the impregnating agent comprises the following components in parts by weight: 15-30 parts of modified epoxy resin, 15-25 parts of epoxy phenolic resin, 3-5 parts of epoxy silane coupling agent, 5-8 parts of polyethylene glycol, 3-5 parts of polyethylene oxide, 1-3 parts of aliphatic ammonium salt and 1-2 parts of chloroammonia. By coating the impregnating agent on the surface of the modified carbon fibers and the yarn in sequence, the blended yarn is endowed with better flexibility and skin compatibility, and meanwhile, the flame-retardant performance is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of blended yarn and its preparation method, belong to the technical field of blended yarn. BACKGROUND

[0002] With the rapid development of modern textile science and technology, people's demand for functional textiles is increasing, not just meet the simple wearing requirements of textile fabric, in addition to the general physical and mechanical properties of textile, it should also have certain special functions, such as anti-radiation, anti-static, flame retardant, anti-ultraviolet, etc., to protect the safety and health of the person.

[0003] High-performance fiber mainly refers to high-strength, high-modulus, high-temperature and chemical resistance fiber, which is a functional fiber with high load capacity and high durability. At present, common high-performance fibers include carbon fiber, aramid fiber, glass fiber and basalt fiber. Among them, carbon fiber has the inherent nature of carbon material, and also has the conductivity and thermal conductivity of metal material, the heat resistance and corrosion resistance of ceramic material, the softness and weavability of textile fiber, and the lightness and easy processing performance of polymer material, which is a functional material and structural material with multiple functions and multiple uses. Chinese invention patent CN103849967A discloses a method for manufacturing fireproof carbon fiber yarn, comprising: a) first cleaning cotton fibers and cutting glass fibers and carbon fibers, b) mixing the treated carbon fibers, glass fibers and cotton fibers in a weight ratio of 2:2:1 and opening and carding the mixed fibers, c) rolling the carded mixed fibers into blended slivers, d) doubling every 4 slivers and treating the doubled slivers for fire resistance, e) twisting the treated slivers into roving, then twisting the roving into yarn, and finally winding the manufactured yarn. The fireproof carbon fiber yarn manufactured by the manufacturing method has the advantages of high reliability, good fire resistance and high material strength; during use, the coating material will decompose when heated, release fire retardant and improve the fireproof ability, at the same time, the broken carbon fibers and glass fibers are exposed during manufacturing, causing discomfort to the wearer, even causing injury, resulting in poor wearing performance of the fabric made of the yarn. SUMMARY

[0004] In order to solve the above problems, a kind of blended yarn and its preparation method are provided, by coating the modified carbon fiber and the surface of the yarn with a wetting agent in sequence, giving the blended yarn better flexibility and skin compatibility, ensuring the flame retardant performance while improving the wearing performance.

[0005] The present application adopts the following technical solutions:

[0006] According to one aspect of the present application, a method for preparing a blended yarn is provided, comprising the following steps:

[0007] Step one, evenly coat the sizing agent on the surface of the modified carbon fiber, dry to obtain the modified carbon fiber roving;

[0008] Step two, twist the modified carbon fiber roving every 1-3 strands, the twist degree is 80-100 twists / m, and twist the synthetic fiber roving every 3-5 strands, the twist degree is 70-90 twists / m;

[0009] Step three, after twisting, the modified carbon fiber roving and the synthetic fiber roving are combined, and then the sizing agent is coated on the surface of the combined yarn, and dried to obtain the blended yarn.

[0010] Among them, the sizing agent includes the following components by weight:

[0011] 15-30 parts of modified epoxy resin, 15-25 parts of epoxy phenolic resin, 3-5 parts of epoxy silane coupling agent, 5-8 parts of polyethylene glycol, 3-5 parts of polyepoxy ethylene, 1-3 parts of aliphatic ammonium salt and 1-2 parts of ammonium chloride.

[0012] In the preparation process of the blended yarn, the epoxy groups on the resin in the sizing agent form covalent bonds with the amino functional groups on the rectorite in the modified carbon fiber, improving the interfacial strength between the two, thus reducing the wear of the carbon fiber during processing and avoiding the phenomenon of flying broken yarn; after twisting, the sizing agent is coated again to enhance the bundling of the blended yarn, improve its breaking capacity and flame retardant performance, to meet the subsequent requirements of chopping, spinning and other operations.

[0013] Among them, the epoxy groups in the modified epoxy resin and the epoxy phenolic resin not only can form covalent bonds with the amino functional groups on the modified carbon fiber, improving the interfacial adhesion between the two, but also further improve the flame retardant performance of the yarn, ensuring the mechanical strength and thermal stability of the yarn; the addition of epoxy silane coupling agent helps to improve the compatibility of the yarn and the resin; polyepoxy ethylene has good flexibility, and polyethylene glycol has good film-forming and lubricating properties, and the two work together to make the yarn softer and at the same time inhibit the accumulation of static electricity on its surface; the aliphatic ammonium salt and ammonium chloride can form a conductive path on the surface of the yarn, allowing the generated charge to quickly move away through the conductive path, avoiding the phenomenon of fiber opening.

[0014] Optionally, the blending ratio of the modified carbon fiber roving to the synthetic fiber roving is 1:(2-4).

[0015] Optionally, the drying temperature in step one and step three is 80-150℃.

[0016] Optionally, the coating thickness of the sizing agent on the surface of the modified carbon fiber is 0.5-1μm, and the coating thickness of the sizing agent on the surface of the yarn is 1-2μm.

[0017] Optionally, the method for preparing the modified carbon fiber comprises the following steps:

[0018] (1) carbon fibers are immersed in a concentrated nitric acid solution at 60-80℃ for 0.5-1.5h, washed with water until neutral, then the dried carbon fibers are immersed in a mixed solution of triethylamine and formaldehyde, and refluxed at 70-90℃, 30-50v / v% of the pretreatment agent is added to the obtained mixture and stirred for 15-20h to obtain pretreated carbon fibers;

[0019] (2) attapulgite is dispersed in deionized water, the obtained suspension is poured into acetone and stirred for 0.5-1.5h, then the precipitate is obtained by filtration, the precipitate is poured into acetone, 20-40v / v% of a silane coupling agent is added to the obtained slurry, and refluxed at 60-80℃ for 10-20h, then dried to obtain functionalized attapulgite;

[0020] (3) the pretreated carbon fibers are placed in an aqueous solution containing the functionalized attapulgite, and stirred at 50-70℃ for 0.5-1.5h, then washed and dried to obtain the modified carbon fiber.

[0021] After the carbon fiber yarn and attapulgite are respectively functionalized with quaternary ammonium cations and amino groups, the sodium cations in the amino-functionalized attapulgite can be exchanged with the quaternary ammonium cations on the surface of the pretreated carbon fiber yarn, so that the amino-functionalized attapulgite is grafted to the surface of the pretreated carbon fiber yarn, thereby reducing the defects on the surface of the carbon fiber yarn and making the tensile strength uniformly distributed, so that the carbon fiber is less likely to appear broken yarn phenomenon during processing, and can better bond with the sizing agent.

[0022] Optionally, in step (1), the pretreatment agent is at least one of 3-chloro-2-hydroxypropyltrimethylammonium chloride, 2-chloroethyltrimethylammonium chloride and 2-hydroxyethyltrimethylammonium chloride.

[0023] Optionally, in step (2), the silane coupling agent is at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane and 3-aminopropyltriisopropoxysilane.

[0024] Optionally, in step (3), the mass ratio of the pretreated carbon fiber to the functionalized attapulgite is 1:(1.5-3).

[0025] Optionally, the method for preparing the modified epoxy resin comprises the following steps:

[0026] S1, expandable graphite and isocyanic acid propyl triethoxysilane are added to tetrahydrofuran, and refluxed at 50-70℃ for 3-5h, then washed and dried to obtain pretreated expandable graphite;

[0027] S2, uniformly mix propyl triethoxysilane isocyanate and epoxy resin, stir at 50-70℃ for 3-5h, then add pretreated expandable graphite, stir at room temperature for 15-30min, to obtain modified epoxy resin.

[0028] By introducing propyl triethoxysilane isocyanate into the structures of epoxy resin and expandable graphite respectively, chemical condensation between the two is realized, thereby improving the compatibility between the organic phase and the inorganic phase, wherein the expandable graphite can expand to form a barrier structure at high temperature, slowing down heat transfer and hindering gas diffusion, thereby improving the flame retardance and thermal stability of the modified epoxy resin.

[0029] Optionally, in step S1, the mass ratio of expandable graphite and propyl triethoxysilane isocyanate is 1:(3-7);

[0030] In step S2, the mass ratio of propyl triethoxysilane isocyanate and epoxy resin is 1:(2-3).

[0031] Optionally, the synthetic fiber is at least one of polyester, nylon and acrylic.

[0032] According to another aspect of the present application, a blended yarn is provided, which is prepared by the preparation method of the blended yarn described above.

[0033] In the present application, "room temperature" refers to 20-30℃.

[0034] The beneficial effects of the present application include but are not limited to:

[0035] The blended yarn and the preparation method thereof of the present application, by coating the infiltration agent on the surface of the modified carbon fiber, the epoxy groups on the resin in the infiltration agent and the amino functional groups on the rectorite in the modified carbon fiber form covalent bond, improving the interfacial strength between the two, thereby reducing the abrasion of carbon fiber in the processing process, and avoiding the phenomenon of flying hair broken yarn; by coating the infiltration agent on the blended yarn after blending, the blended yarn is given better flexibility and skin compatibility, avoiding the appearance of fiber opening on the surface of the blended yarn due to static accumulation, ensuring the flame retardance while improving the wearability; wherein by modifying the carbon fiber, the defects on the surface of the carbon fiber yarn can be reduced, and the tensile strength is uniformly distributed, the carbon fiber is not easy to appear the phenomenon of flying hair broken yarn in the processing process, and better interfacial adhesion with the infiltration agent can be achieved; by modifying the epoxy resin, the flame propagation can be slowed down, so that the blended yarn remains stable under high temperature conditions, improving the flame retardance and thermal stability of the modified epoxy resin. DETAILED DESCRIPTION

[0036] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the properties. The endpoints of the ranges and any values are provided as approximations only, and are understood to be open-ended. Thus, the endpoints of the ranges and any values are not to be understood as being stated to be the only values that can be used to define the range or the value. The range and any value are understood to be inclusive of values near the recited approximate values.

[0037] Unless otherwise indicated, conventional methods or those modifications known to those of ordinary skill in the art were employed in the examples. Unless otherwise indicated, the materials used were commercially available from the manufacturers (reagents, chemicals, and the like) cited in the text.

[0038] In the present application, the diameter of the carbon fiber used is 3-5 μm, and the diameter of the synthetic fiber is 10-20 μm.

[0039] Example 1

[0040] A method for preparing a blended yarn, comprising the steps of:

[0041] Step 1, uniformly applying a sizing agent to the surface of the modified carbon fiber, drying at 80°C, and obtaining a modified carbon fiber filament with a coating thickness of 0.5 μm;

[0042] Step 2, twisting each 1 strand of the modified carbon fiber filament at a twist of 100 twists / m, and twisting each 3 strands of the terephthalic acid filament at a twist of 90 twists / m;

[0043] Step 3, combining the twisted modified carbon fiber filament and the terephthalic acid filament at a blending ratio of 1:2, and applying a sizing agent to the surface of the combined yarn, drying at 80°C, and obtaining a blended yarn with a coating thickness of 1 μm;

[0044] The method for preparing the modified carbon fiber comprises the steps of:

[0045] (1) immersing the carbon fiber in a 60°C concentrated nitric acid solution for 1.5 h, washing to neutral, then immersing the dried carbon fiber in a mixed solution of 2 v / v% triethylamine and formaldehyde, refluxing at 70°C, adding 30 v / v% 2-hydroxyethyltrimethylammonium chloride to the obtained mixture, and stirring for 20 h to obtain a pretreated carbon fiber;

[0046] (2) dispersing the rectorite in deionized water to form a suspension, pouring the suspension into acetone and stirring for 0.5 h, filtering to obtain a precipitate, then pouring the precipitate into acetone, adding 20 v / v% 3-aminopropyltriisopropoxysilane to the formed slurry, refluxing at 60°C for 10 h, and drying to obtain a functionalized rectorite;

[0047] (3) Take the pretreated carbon fiber and functionalized retardite in a mass ratio of 1:1.5, place the pretreated carbon fiber in an aqueous solution containing functionalized retardite, stir at 50°C for 1.5 h, wash and dry to obtain modified carbon fiber.

[0048] The wetting agent, by weight, comprises the following components:

[0049] 15 parts modified epoxy resin, 25 parts epoxy phenolic resin, 3 parts epoxy silane coupling agent, 5 parts polyethylene glycol, 5 parts polyethylene oxide, 1 part aliphatic ammonium salt and 2 parts ammonium chloride.

[0050] The preparation method of modified epoxy resin includes the following steps:

[0051] S1. Add expandable graphite and propyltriethoxysilane isocyanate in a mass ratio of 1:3 to tetrahydrofuran, reflux at 50°C for 5 hours, wash and dry to obtain pretreated expandable graphite.

[0052] S2. Mix propyltriethoxysilane isocyanate and epoxy resin in a mass ratio of 1:2 until homogeneous, stir at 50°C for 5 hours, then add pretreated expandable graphite and stir at room temperature for 15 minutes to obtain modified epoxy resin.

[0053] Example 2

[0054] A method for preparing blended yarn includes the following steps:

[0055] Step 1: Apply the sizing agent evenly to the surface of the modified carbon fiber and dry it at 150°C. The coating thickness is 1μm to obtain the modified carbon fiber precursor.

[0056] Step 2: Twist the modified carbon fiber precursor into 3 strands at a twist of 80 twists / m, and twist the nylon precursor into 5 strands at a twist of 70 twists / m.

[0057] Step 3: Combine the twisted modified carbon fiber precursor and nylon precursor at a blending ratio of 1:4, then coat the surface of the combined yarn with a sizing agent and dry at 150°C to a coating thickness of 2μm to obtain the blended yarn.

[0058] The preparation method of modified carbon fiber includes the following steps:

[0059] (1) Immerse the carbon fiber in a concentrated nitric acid solution at 80°C for 0.5 h, wash it with water until neutral, then immerse the dried carbon fiber in a mixed solution of 2 v / v% triethylamine and formaldehyde, and reflux it at 90°C. Add 50 v / v% 2-chloroethyltrimethylammonium chloride to the mixture and continue stirring for 15 h to obtain the pretreated carbon fiber.

[0060] (2) Disperse raptor in deionized water, pour the resulting suspension into acetone and stir for 1.5 h, filter to obtain precipitate, then pour the precipitate into acetone, add 40 v / v% 3-aminopropyltriethoxysilane to the resulting slurry, reflux at 80 °C for 20 h, and dry to obtain functionalized raptor.

[0061] (3) Take the pretreated carbon fiber and functionalized retardite in a mass ratio of 1:3, place the pretreated carbon fiber in an aqueous solution containing functionalized retardite, stir at 70°C for 0.5 h, wash and dry to obtain modified carbon fiber.

[0062] The wetting agent, by weight, comprises the following components:

[0063] 30 parts modified epoxy resin, 15 parts epoxy phenolic resin, 5 parts epoxy silane coupling agent, 8 parts polyethylene glycol, 3 parts polyethylene oxide, 3 parts aliphatic ammonium salt and 1 part ammonium chloride.

[0064] The preparation method of modified epoxy resin includes the following steps:

[0065] S1. Add expandable graphite and propyltriethoxysilane isocyanate in a mass ratio of 1:7 to tetrahydrofuran, reflux at 70°C for 3 hours, wash and dry to obtain pretreated expandable graphite.

[0066] S2. Mix propyltriethoxysilane isocyanate and epoxy resin in a mass ratio of 1:3, stir at 70°C for 3 hours, then add pretreated expandable graphite and stir at room temperature for 30 minutes to obtain modified epoxy resin.

[0067] Example 3

[0068] A method for preparing blended yarn includes the following steps:

[0069] Step 1: Apply the sizing agent evenly to the surface of the modified carbon fiber and dry it at 110℃. The coating thickness is 0.8μm to obtain the modified carbon fiber precursor.

[0070] Step 2: Twist every 2 strands of modified carbon fiber precursor to a twist of 90 twists / m, and twist every 4 strands of acrylic precursor to a twist of 80 twists / m.

[0071] Step 3: Combine the twisted modified carbon fiber precursor and acrylic precursor at a blending ratio of 1:3, then coat the surface of the combined yarn with a sizing agent and dry at 110℃ to a coating thickness of 1.5μm to obtain the blended yarn.

[0072] The preparation method of modified carbon fiber includes the following steps:

[0073] (1) The carbon fiber was immersed in a concentrated nitric acid solution at 70°C for 1 hour, washed with water until neutral, and then the dried carbon fiber was immersed in a mixed solution of 2 v / v% triethylamine and formaldehyde and refluxed at 80°C. 40 v / v% 3-chloro-2-hydroxypropyltrimethylammonium chloride was added to the mixture and stirred for 18 hours to obtain the pretreated carbon fiber.

[0074] (2) Disperse raptor in deionized water, pour the resulting suspension into acetone and stir for 1 hour. After filtration, obtain the precipitate. Then pour the precipitate into acetone and add 30 v / v% 3-aminopropyltrimethoxysilane to the resulting slurry. Reflux at 70°C for 15 hours and dry to obtain functionalized raptor.

[0075] (3) Take the pretreated carbon fiber and functionalized retardite in a mass ratio of 1:2, place the pretreated carbon fiber in an aqueous solution containing functionalized retardite, stir at 60°C for 1 hour, wash and dry to obtain modified carbon fiber.

[0076] The wetting agent, by weight, comprises the following components:

[0077] 22 parts modified epoxy resin, 20 parts epoxy phenolic resin, 4 parts epoxy silane coupling agent, 7 parts polyethylene glycol, 4 parts polyethylene oxide, 2 parts aliphatic ammonium salt and 1.5 parts ammonium chloride;

[0078] The preparation method of modified epoxy resin includes the following steps:

[0079] S1. Add expandable graphite and propyltriethoxysilane isocyanate in a mass ratio of 1:5 to tetrahydrofuran, reflux at 60°C for 4 hours, wash and dry to obtain pretreated expandable graphite.

[0080] S2. Mix propyltriethoxysilane isocyanate and epoxy resin in a mass ratio of 1:2.5 until homogeneous, stir at 60°C for 4 hours, then add pretreated expandable graphite and stir at room temperature for 20 minutes to obtain modified epoxy resin.

[0081] Example 4

[0082] The difference from Example 3 is that the blending ratio of modified carbon fiber precursor to synthetic fiber precursor is 1:6.

[0083] Example 5

[0084] The difference from Example 3 is that the coating thickness in step one is 2 μm and the coating thickness in step three is 0.5 μm.

[0085] Example 6

[0086] The difference from Example 3 is that:

[0087] The wetting agent, by weight, comprises the following components:

[0088] 10 parts modified epoxy resin, 30 parts epoxy phenolic resin, 1 part epoxy silane coupling agent, 2 parts polyethylene glycol, 8 parts polyethylene oxide, 0.1 parts aliphatic ammonium salt and 3 parts ammonium chloride.

[0089] Comparative Example 1

[0090] The difference from Example 3 is that the method for preparing modified carbon fiber is not disclosed, and modified carbon fiber is replaced with carbon fiber.

[0091] Comparative Example 2

[0092] The difference from Example 3 is that the preparation method of the modified epoxy resin is not disclosed, and the modified epoxy resin is replaced with epoxy resin.

[0093] Comparative Example 3

[0094] The difference from Example 3 is that:

[0095] Step 3: Combine the twisted modified carbon fiber precursor and acrylic fiber precursor at a blending ratio of 1:3 to obtain the blended yarn.

[0096] Comparative Example 4

[0097] The difference from Example 3 is that:

[0098] The preparation method of modified carbon fiber includes the following steps:

[0099] (1) The carbon fiber was immersed in a concentrated nitric acid solution at 70°C for 1 hour, washed with water until neutral, and dried to obtain the pretreated carbon fiber.

[0100] (2) Disperse raptor in deionized water, pour the resulting suspension into acetone and stir for 1 hour. After filtration, obtain the precipitate. Then pour the precipitate into acetone and add 30 v / v% 3-aminopropyltrimethoxysilane to the resulting slurry. Reflux at 70°C for 15 hours and dry to obtain functionalized raptor.

[0101] (3) Take the pretreated carbon fiber and functionalized retardite in a mass ratio of 1:2, place the pretreated carbon fiber in an aqueous solution containing functionalized retardite, stir at 60°C for 1 hour, wash and dry to obtain modified carbon fiber.

[0102] Comparative Example 5

[0103] The difference from Example 3 is that rettostele is replaced with montmorillonite.

[0104] Comparative Example 6

[0105] The difference from Example 3 is that the modified epoxy resin and its preparation method are not disclosed, the epoxy phenolic resin is replaced with phenolic resin, and the epoxy silane coupling agent is replaced with an amino silane coupling agent.

[0106] The surface of the blended yarns prepared above was observed. The blended yarns prepared in Examples 1-5 and Comparative Examples 1-6 were placed in a limiting oxygen index tester according to GB / T5454 to measure the limiting oxygen index. The surface resistivity of the blended yarns was tested according to AATCC 76-2019. The results are shown in Table 1.

[0107] Table 1

[0108] Test No. Appearance Limiting oxygen index (%) Surface resistance (Ω) Example 1 Smooth, glossy 29.3 3.4 x 10 8 ]] Example 2 Smooth, glossy 29.5 3.0 x 10 8 ]]> Example 3 Smooth, glossy 29.7 3.2 x 10 8 ]]> Example 4 Smooth, glossy 28.4 3.2 x 10 8 ]] Example 5 Smooth, glossy 27.2 5.1 x 10 8 ]]> Example 6 Smooth, glossy 26.4 6.7 x 10 8 ]]> Comparative Example 1 Rough 25.8 5.9 x 10 8 ]]> Comparative Example 2 Smooth, glossy 23.6 3.2 x 10 8 ]] Comparative Example 3 Smooth, fuzzy 20.5 9.6 x 10 8 ]] Comparative Example 4 Smooth, glossy 26.7 3.2 x 10 8 ]]> Comparative Example 5 Smooth, glossy 27.5 3.2 x 10 8 ]]> Comparative Example 6 Slight cracking 21.3 7.4 x 10 8 ]]>

[0109] The mechanical properties of the blended yarns obtained in Examples 1-5 and Comparative Examples 1-6 were tested, and the results are shown in Table 2.

[0110] Table 2

[0111] Test No. Tensile strength (MPa) Shear strength (MPa) Flexural strength (MPa) Example 1 124.5 18.3 206.5 Example 2 122.7 18.1 205.2 Example 3 126.3 18.6 208.4 Example 4 102.4 16.8 193.7 Example 5 100.8 15.3 186.0 Example 6 111.6 17.4 196.0 Comparative Example 1 85.8 13.2 147.4 Comparative Example 2 106.5 17.1 195.3 Comparative Example 3 67.2 10.8 126.5 Comparative Example 4 94.6 14.5 161.7 Comparative Example 5 115.2 17.6 198.4 Comparative Example 6 76.4 12.0 135.2

[0112] As can be seen from the results in Tables 1 and 2, changing any of the preparation conditions affects the overall performance of the resulting blended yarn, making it unable to meet the requirements for wear. The blended yarn prepared by the method of the present invention has both excellent flame retardant and mechanical properties, while also increasing skin compatibility and good wear performance, and has broad application prospects.

[0113] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing blended yarn, characterized in that, Includes the following steps: Step 1: Apply the sizing agent evenly to the surface of the modified carbon fiber and dry it to obtain the modified carbon fiber precursor. Step 2: Twist 1-3 strands of modified carbon fiber precursor at a twist rate of 80-100 twists / m, and twist 3-5 strands of synthetic fiber precursor at a twist rate of 70-90 twists / m. Step 3: Combine the twisted modified carbon fiber precursor and the synthetic fiber precursor, then coat the surface of the combined yarn with a sizing agent and dry it to obtain the blended yarn. The wetting agent, by weight, comprises the following components: 15-30 parts modified epoxy resin, 15-25 parts epoxy phenolic resin, 3-5 parts epoxy silane coupling agent, 5-8 parts polyethylene glycol, 3-5 parts polyethylene oxide, 1-3 parts aliphatic ammonium salt and 1-2 parts ammonium chloride; The method for preparing the modified carbon fiber includes the following steps: (1) Immerse the carbon fiber in a concentrated nitric acid solution at 60-80℃ for 0.5-1.5h, wash it with water until neutral, then immerse the dried carbon fiber in a mixed solution of triethylamine and formaldehyde, and reflux it at 70-90℃. Add 30-50 v / v% pretreatment agent to the mixture and continue stirring for 15-20h to obtain the pretreated carbon fiber. (2) Disperse raptor in deionized water, pour the resulting suspension into acetone and stir for 0.5-1.5 h, filter to obtain precipitate, then pour the precipitate into acetone, add 20-40 v / v% silane coupling agent to the resulting slurry, reflux at 60-80℃ for 10-20 h, and dry to obtain functionalized raptor. (3) The pretreated carbon fiber is placed in an aqueous solution containing functionalized retardite and stirred at 50-70℃ for 0.5-1.5h. After washing and drying, the modified carbon fiber is obtained. In step (1), the pretreatment agent is at least one of 3-chloro-2-hydroxypropyltrimethylammonium chloride, 2-chloroethyltrimethylammonium chloride, and 2-hydroxyethyltrimethylammonium chloride; In step (2), the silane coupling agent is at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane and 3-aminopropyltriisopropoxysilane.

2. The method for preparing blended yarn according to claim 1, characterized in that, The blending ratio of the modified carbon fiber precursor to the synthetic fiber precursor is 1:(2-4).

3. The method for preparing blended yarn according to claim 1, characterized in that, In step (3), the mass ratio of the pretreated carbon fiber to the functionalized retardant is 1:(1.5-3).

4. The method for preparing blended yarn according to claim 1, characterized in that, The preparation method of the modified epoxy resin includes the following steps: S1. Add expandable graphite and propyltriethoxysilane isocyanate to tetrahydrofuran, reflux at 50-70℃ for 3-5 h, wash and dry to obtain pretreated expandable graphite. S2. Mix propyltriethoxysilane isocyanate and epoxy resin evenly, stir at 50-70℃ for 3-5 hours, then add pretreated expandable graphite, stir at room temperature for 15-30 minutes to obtain modified epoxy resin.

5. The method for preparing blended yarn according to claim 4, characterized in that, In step S1, the mass ratio of expandable graphite to propyltriethoxysilane is 1:(3-7); In step S2, the mass ratio of propyltriethoxysilane isocyanate to epoxy resin is 1:(2-3).

6. The method for preparing blended yarn according to claim 1, characterized in that, The synthetic fiber is at least one of polyester, nylon, and acrylic.

7. A blended yarn, characterized in that, The blended yarn is prepared by the method for preparing blended yarn according to any one of claims 1-6.