Preparation method of composite structure electromagnetic shielding yarn containing regenerated cotton fiber and yarn

Abstract

The invention discloses a preparation method of composite structure electromagnetic shielding yarn containing regenerated cotton fiber and yarn, and the preparation method comprises the following steps: S1, spinning stainless steel filaments and fine staple cotton rough yarn by adopting a ring spinning process, and enabling the fine staple cotton fiber to cover the periphery of the stainless steel filaments to prepare initial covering yarn; s2, spinning the primary covering yarn and the regenerated cotton slivers by adopting a friction spinning process, so that the periphery of the primary covering yarn is coated with regenerated cotton fibers, and wrap yarn is prepared; and S3, spinning the wrap yarn and the fine-staple cotton rough yarn by adopting a ring spinning process, so that the periphery of the wrap yarn is coated with the fine-staple cotton fiber, and the yarn is prepared. According to the design, the multi-layer composite structure yarn is constructed through a three-step combined process, so that regenerated cotton fibers which are difficult to apply due to short fibers and poor cohesive force can tightly wrap smooth stainless steel filaments, and the problem of core leakage is solved; meanwhile, the mass ratio of the regenerated cotton fibers in the yarn is increased to 30% or above through the friction spinning technology, and the utilization efficiency of regenerated cotton resources is greatly improved.

Description

Technical Field

[0001] This invention relates to a method for preparing a composite structure yarn and the yarn itself, belonging to the field of functional textile materials technology, and particularly to a method for preparing a composite structure electromagnetic shielding yarn containing recycled cotton fibers and the yarn itself. Background Technology

[0002] With the rapid development of electronic devices and wireless communication technologies, the potential impact of electromagnetic radiation on the environment and human health has received increasing attention, and the demand for electromagnetic protection has become increasingly urgent. To reduce electromagnetic interference and achieve electromagnetic shielding, conductive fibers and metal materials are gradually being applied in the textile industry to manufacture electromagnetic shielding fabrics. Among these methods, core-spun yarn, which uses stainless steel or copper filaments as core yarns and coats them with non-conductive textile fibers such as cotton or polyester to form a soft coating structure, is currently one of the important ways to prepare electromagnetic shielding yarns. Meanwhile, with the deepening of the concept of sustainable development, the resource recycling of waste textiles has become an important development direction for the textile industry. Regenerated cotton fiber, as a major product of waste textile recycling, has significant environmental benefits and cost advantages. Against this backdrop, the industry is exploring blending recycled cotton fiber with virgin cotton fiber and then coating it with stainless steel filaments to prepare yarns that combine environmental protection properties with electromagnetic shielding functions.

[0003] However, in practice, it has been found that recycled cotton fibers have inherent defects during the recycling process, such as shortened fiber length and reduced or even lost natural surface curvature, resulting in significantly lower cohesion than virgin cotton fibers. When using traditional core-spun yarn technology to wrap this type of recycled cotton / fine cotton blended yarn onto smooth stainless steel filaments, the poor cohesion of the recycled cotton fibers means that even with a low recycled cotton content, the resulting blended yarn structure remains relatively loose, making it difficult to form a tight and uniform wrap around the stainless steel filaments. This easily leads to a "core leakage" phenomenon, where the core filaments are exposed, resulting in fluctuations in electromagnetic shielding effectiveness and unstable protective performance. Therefore, overcoming the inherent defects of recycled cotton fibers and enabling recycled cotton / fine cotton blended yarn to form a tight and uniform wrap around stainless steel filaments, thus avoiding core leakage, has become a pressing technical problem to be solved in this field.

[0004] The information disclosed in this background section is intended only to enhance understanding of the overall background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to overcome the defect in the prior art that recycled cotton / fine cotton blended yarn is difficult to form a tight and uniform wrap around stainless steel filaments, and to provide a method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers that enables recycled cotton / fine cotton blended yarn to form a tight and uniform wrap around stainless steel filaments, as well as the yarn itself.

[0006] To achieve the above objectives, the technical solution of the present invention is:

[0007] A method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers, the method comprising the following steps:

[0008] S1. Stainless steel filament and roving are spun using ring spinning process, so that the roving is stretched to form roving fibers that cover the outer periphery of stainless steel filament, thus producing initial wrapped yarn.

[0009] S2. The primary wrapped yarn and the recycled cotton sliver are spun using a friction spinning process, so that the recycled cotton fibers formed after the recycled cotton sliver is combed cover the outer periphery of the primary wrapped yarn to obtain a covered yarn.

[0010] S3. The covered yarn and the roving of fine cotton are spun using a ring spinning process, so that the fine cotton fibers formed after the roving of fine cotton are drawn and covered on the outer periphery of the covered yarn, to obtain a composite electromagnetic shielding yarn containing recycled cotton fibers.

[0011] In step S1, the linear density of the fine cotton roving is 600 tex-650 tex, and the linear density of the stainless steel filament is 3 tex-5 tex; the ring spinning process is Sirofil spinning, and the process parameters are: spindle speed of 5800 r / min-6200 r / min, twist coefficient of 340-380, and back zone draft ratio of 1.4-1.6.

[0012] In step S1, the linear density of the initial wrapped yarn is 14 tex-16 tex, wherein the mass percentage of stainless steel filament is 25%-30% and the mass percentage of fine cotton fiber is 70%-75%.

[0013] In step S2, the method for preparing the recycled cotton sliver includes the following steps: first, the recycled cotton raw material is placed in an opening machine to open and remove impurities to obtain a recycled cotton fiber layer; then, the recycled cotton fiber layer is fed into a carding machine to form a recycled cotton fiber web; finally, the recycled cotton fiber web is drawn through a drawing frame to obtain a recycled cotton sliver.

[0014] In the opening and impurity removal process, the cylinder speed of the opening machine is 400 r / min-430 r / min, the doffer speed is 200 r / min-215 r / min, and the feed line speed is 0.70 m / min-0.75 m / min; in the carding process, the cylinder speed of the carding machine is 380 r / min-420 r / min, the doffer speed is 180 r / min-200 r / min, and the feed line speed is 0.09 m / min-0.11 m / min; in the drawing process, the first drawing uses 3-5 slivers combined with a draft ratio of 3.5-4.5, and the second and third drawing both use 2-4 slivers combined with a draft ratio of 2.5-3.5; the linear density of the resulting recycled sliver is 300 tex-400 tex.

[0015] In step S2, the process parameters for friction spinning are: the rotation speed of the friction roller is 2700 r / min to 5100 r / min, and the rotation speed of the combing roller is 2500 r / min to 4000 r / min.

[0016] In step S2, the linear density of the resulting covered yarn is 28 tex-32 tex, wherein the mass percentage of stainless steel filament is 12%-14%, the mass percentage of fine cotton fiber is 35%-37%, and the mass percentage of recycled cotton fiber is 49%-51%.

[0017] In step S3, the process parameters for ring spinning are: spindle speed of 6800 r / min-7200 r / min, twist coefficient of 350-370, and back zone draft ratio of 1.1-1.3.

[0018] In step S3, the linear density of the composite electromagnetic shielding yarn containing recycled cotton fiber is 44 tex-46 tex, wherein the mass percentage of stainless steel filament is 8.5%-9.5%, the mass percentage of fine cotton fiber is 57.5%-58.5%, and the mass percentage of recycled cotton fiber is 32%-34%.

[0019] A yarn is prepared by the method described above for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers. The yarn has a three-layer composite structure consisting of a stainless steel filament core, a fine cotton inner layer, a recycled cotton middle layer, and a fine cotton outer layer, arranged sequentially from the inside out.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. This invention discloses a method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers. The preparation method includes the following steps: S1. A ring spinning process is used to spin stainless steel filaments and fine cotton roving, so that the fine cotton fiber bundles formed after the fine cotton roving is drawn cover the outer periphery of the stainless steel filaments, thus obtaining a primary covered yarn; S2. A friction spinning process is used to spin the primary covered yarn and recycled cotton sliver, so that the recycled cotton fibers formed after the recycled cotton sliver is combed cover the outer periphery of the primary covered yarn, thus obtaining a covered yarn; S3. A ring spinning process is used to spin the covered yarn and fine cotton roving, so that the fine cotton fiber bundles formed after the fine cotton roving is drawn cover the outer periphery of the covered yarn, thus obtaining a composite electromagnetic shielding yarn containing recycled cotton fibers. The advantages of this invention are:

[0022] First, the first step involves using ring spinning to coat the surface of stainless steel filaments with roving made of fine cotton. The twisting effect of ring spinning causes the cotton fibers to tightly wrap around the stainless steel filaments, generating significant centripetal pressure between the fibers and firmly fixing the core filament in the center of the yarn. This layer serves two purposes: firstly, it leverages the long length and high strength of the cotton fibers to create a dense "inner sheath," preventing core filament misalignment from the outset; secondly, it provides a structurally stable and smooth core axis foundation for subsequent coating layers, allowing the recycled cotton fibers to adhere evenly.

[0023] Secondly, the second step involves using a friction spinning process to coat the recycled cotton fiber sliver onto the primarily wrapped yarn. The working principle of friction spinning is to utilize the high-speed rotation of friction rollers to generate a friction field, which deposits and twists the combed recycled cotton fibers layer by layer onto the surface of the primarily wrapped yarn. Because friction spinning provides a gentler grip on the fibers, it does not cause secondary damage to the recycled cotton fibers. Furthermore, its characteristics of thorough opening and uniform deposition allow the recycled cotton fibers, which have poor cohesion, to adhere to the surface of the primarily wrapped yarn in a loose but continuous state, forming a "buffer filling layer" of a certain thickness. Although this layer itself is not very dense, it effectively fills the microscopic depressions and fiber gaps on the surface of the primarily wrapped yarn, forming a secondary locking effect and further constraining any possible displacement of the core yarn.

[0024] Third, the third step involves again using ring spinning to wrap the roving of the cotton fibers onto the cover yarn. This time, the role of ring spinning differs from the previous step: while the previous step involved "wrapping," this step involves "compression." During the twisting process, the outer cotton fibers generate a strong radial shrinkage force, applying uniform centripetal pressure to the inner cover yarn. This pressure further compacts the originally loose recycled cotton middle layer, reducing the gaps between fibers, and simultaneously creating a tighter interface between the recycled cotton fibers and the inner roving and outer cotton fibers.

[0025] Therefore, the three-layer composite coating structure constructed by the three-step process of "ring spinning - friction spinning - ring spinning" in this invention enables the recycled cotton / fine cotton blended yarn to form a complete, tight and uniform wrapping of the smooth stainless steel filament, eliminating the phenomenon of core filament exposure, ensuring the continuous and stable conductive path of the yarn, and significantly improving the reliability of electromagnetic shielding performance.

[0026] 2. This invention discloses a method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers. In this yarn, recycled cotton fibers are innovatively used as a separate intermediate coating layer. A friction spinning process, highly adaptable to short fibers, is specifically employed to complete the coating of this layer. This eliminates the need to rely on the inherent cohesion of the recycled cotton fibers themselves, allowing them to adhere uniformly and densely to the surface of the initial yarn. This enables even short-length, poorly cohesive recycled cotton fibers to form a stable intermediate coating layer, achieving a recycled cotton fiber content of over 30% in the final yarn. This overcomes the technical bottleneck of limited recycled cotton addition ratios in traditional blending processes (in traditional recycled cotton / fine cotton blended yarns, the addition ratio of recycled cotton fibers is generally limited to less than 10%). Therefore, this invention achieves a high and stable addition ratio of recycled cotton fibers while ensuring yarn quality and overall performance, significantly improving the utilization efficiency of recycled cotton resources. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the spinning process of the present invention;

[0028] Figure 2 This is a longitudinal structural diagram of the initial yarn wrapping in this invention;

[0029] Figure 3 This is a SEM image of the cross-sectional microstructure of the initial wrapped yarn in this invention;

[0030] Figure 4 This is a longitudinal structural diagram of the covering yarn in this invention;

[0031] Figure 5 This is a SEM image of the cross-sectional microstructure of the covering yarn in this invention;

[0032] Figure 6 This is a longitudinal structural diagram of the present invention;

[0033] Figure 7 This is a cross-sectional microstructure SEM image of the present invention. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] See Figure 1 — Figure 7A method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers, the method comprising the following steps:

[0036] S1. Stainless steel filament and roving are spun using ring spinning process, so that the roving is stretched to form roving fibers that cover the outer periphery of stainless steel filament, thus producing initial wrapped yarn.

[0037] S2. The primary wrapped yarn and the recycled cotton sliver are spun using a friction spinning process, so that the recycled cotton fibers formed after the recycled cotton sliver is combed cover the outer periphery of the primary wrapped yarn to obtain a covered yarn.

[0038] S3. The covered yarn and the roving of fine cotton are spun using a ring spinning process, so that the fine cotton fibers formed after the roving of fine cotton are drawn and covered on the outer periphery of the covered yarn, to obtain a composite electromagnetic shielding yarn containing recycled cotton fibers.

[0039] In step S1, the linear density of the fine cotton roving is 600 tex-650 tex, and the linear density of the stainless steel filament is 3 tex-5 tex; the ring spinning process is Sirofil spinning, and the process parameters are: spindle speed of 5800 r / min-6200 r / min, twist coefficient of 340-380, and back zone draft ratio of 1.4-1.6.

[0040] In step S1, the linear density of the initial wrapped yarn is 14 tex-16 tex, wherein the mass percentage of stainless steel filament is 25%-30% and the mass percentage of fine cotton fiber is 70%-75%.

[0041] In step S2, the method for preparing the recycled cotton sliver includes the following steps: first, the recycled cotton raw material is placed in an opening machine to open and remove impurities to obtain a recycled cotton fiber layer; then, the recycled cotton fiber layer is fed into a carding machine to form a recycled cotton fiber web; finally, the recycled cotton fiber web is drawn through a drawing frame to obtain a recycled cotton sliver.

[0042] In the opening and impurity removal process, the cylinder speed of the opening machine is 400 r / min-430 r / min, the doffer speed is 200 r / min-215 r / min, and the feed line speed is 0.70 m / min-0.75 m / min; in the carding process, the cylinder speed of the carding machine is 380 r / min-420 r / min, the doffer speed is 180 r / min-200 r / min, and the feed line speed is 0.09 m / min-0.11 m / min; in the drawing process, the first drawing uses 3-5 slivers combined with a draft ratio of 3.5-4.5, and the second and third drawing both use 2-4 slivers combined with a draft ratio of 2.5-3.5; the linear density of the resulting recycled sliver is 300 tex-400 tex.

[0043] In step S2, the process parameters for friction spinning are: the rotation speed of the friction roller is 2700 r / min to 5100 r / min, and the rotation speed of the combing roller is 2500 r / min to 4000 r / min.

[0044] In step S2, the linear density of the resulting covered yarn is 28 tex-32 tex, wherein the mass percentage of stainless steel filament is 12%-14%, the mass percentage of fine cotton fiber is 35%-37%, and the mass percentage of recycled cotton fiber is 49%-51%.

[0045] In step S3, the process parameters for ring spinning are: spindle speed of 6800 r / min-7200 r / min, twist coefficient of 350-370, and back zone draft ratio of 1.1-1.3.

[0046] In step S3, the linear density of the composite electromagnetic shielding yarn containing recycled cotton fiber is 44 tex-46 tex, wherein the mass percentage of stainless steel filament is 8.5%-9.5%, the mass percentage of fine cotton fiber is 57.5%-58.5%, and the mass percentage of recycled cotton fiber is 32%-34%.

[0047] A yarn is prepared by the method described above for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers. The yarn has a three-layer composite structure consisting of a stainless steel filament core, a fine cotton inner layer, a recycled cotton middle layer, and a fine cotton outer layer, arranged sequentially from the inside out.

[0048] The supplementary technical features of this invention are as follows:

[0049] This invention uses fine cotton fibers as the material for both the initial and outermost covering layers, primarily based on the characteristics of fine cotton fibers: long length, moderate fineness, good softness, and few impurities. The combination of fine cotton fibers and stainless steel filaments effectively wraps the metal core wire, preventing it from being exposed, improving the softness and comfort of the electromagnetic shielding yarn, while also considering the yarn's spinnability and subsequent weaving performance.

[0050] This invention employs friction spinning technology to coat recycled cotton fibers onto the outer layer of the primary yarn. The reason for this is that friction spinning technology has the characteristics of strong adaptability to short fibers, high yarn forming efficiency, and less yarn hairiness. It can make full use of recycled cotton short fibers to form a uniform and dense coating layer, improve the overall mechanical properties of the yarn, and enhance the yarn's environmental properties and functionality.

[0051] In this invention, the process parameters for friction spinning are defined as follows: friction roller speed 2700 r / min–5100 r / min, and carding roller speed 2500 r / min–4000 r / min. This is because the matching of the friction roller speed and the carding roller speed directly affects the coating effect of the recycled cotton fiber and the yarn quality. If the friction roller speed is too low, the fiber twisting is insufficient, the coating layer is loose, and yarn hairiness increases, leading to a decrease in shielding performance. If the friction roller speed is too high, the fiber winding is too tight or it breaks, resulting in poor evenness. If the carding roller speed is too slow, it will cause insufficient fiber carding and an increase in impurities; if the carding roller speed is too fast, the fiber is easily broken and damaged, forming coarse and fine points. Therefore, by controlling the speed of the friction roller within the range of 2700 r / min to 5100 r / min and the speed of the combing roller within the range of 2500 r / min to 4000 r / min, the recycled cotton fibers can be fully combed and evenly transported. At the same time, a dense and firm covering layer is formed on the surface of the initial wrapped yarn, so that the hairiness, breaking strength and evenness CV value of the covered yarn can all reach the ideal state.

[0052] In this invention, the parameters for the third step of ring spinning are defined as follows: spindle speed 6800 r / min–7200 r / min, twist coefficient 350–370, and back zone draft ratio 1.1–1.3. This is because the selection of spindle speed must balance production efficiency and yarn quality. If the spindle speed is too low, production efficiency is low, the yarn structure is loose, and the twist is insufficient, leading to a decrease in shielding performance; if the spindle speed is too high, it is prone to yarn breakage and increased hairiness. The twist coefficient directly affects the tightness of fiber arrangement and the stability of core filament positioning within the yarn. Controlling the twist coefficient within the range of 350–370 ensures tight fiber arrangement and stable core filament positioning, improving yarn strength and uniformity. Controlling the back zone draft ratio at 1.1–1.3 helps maintain yarn thickness uniformity and reduces unevenness and thick spots. The synergistic matching of these parameters ensures that the final yarn has high coverage, excellent mechanical properties, and a stable electromagnetic shielding effect.

[0053] Example 1:

[0054] See Figure 1 — Figure 7 A method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers, the method comprising the following steps:

[0055] S1. Using 630tex linear density fine cotton roving and 4tex linear density stainless steel filament as raw materials, the initial wrapped yarn is spun using the Sirofil spinning process in ring spinning. The process parameters for this step are: spindle speed 6000 r / min, twist coefficient 360, and back zone draft ratio 1.6. The final spun initial wrapped yarn has a linear density of 15tex, with stainless steel filament accounting for 27% and fine cotton fiber accounting for 73%. In this step, to control the linear density of the initial wrapped yarn, a lower amount of cotton fiber was used in the first layer of fine cotton covering. Figure 2 As shown in the red circle, slight core leakage is visible in the longitudinal structure of the initial wrapped yarn; the microstructure of the cross-section of the initial wrapped yarn is as follows. Figure 3 As shown, Figure 3 As can be seen from the red circle, the stainless steel filament is basically in the center of the initial wrapping yarn, achieving the centered positioning of the core filament.

[0056] S2. First, the recycled cotton raw material is placed in an opener for impurity removal. The cylinder speed of the HFX-A0 small opener is controlled at 415 r / min, the doffer speed at 208 r / min, and the feed line speed at 0.722 m / min. Then, the opened recycled cotton fiber layer is fed into a carding machine to form a fiber web. The process parameters of the HFX-A1 small carding machine are a cylinder speed of 400 r / min, a doffer speed of 192.64 r / min, and a feed line speed of 0.102 m / min. Finally, the cotton is drawn into a sliver. The HFX-A2 small drawing frame uses 4 slivers for the first drawing and a design draft ratio of 4. The second and third drawing frames use 2 slivers and a design draft ratio of 3 to improve sliver uniformity. The final product is a recycled cotton sliver with a linear density of 350 tex.

[0057] Next, the recycled cotton sliver obtained above and the initial wrapped yarn obtained in S1 are spun into covered yarn using a friction spinning process. The process parameters for this step are: friction roller speed 4300 r / min, combing roller speed 3500 r / min. The resulting covered yarn has a linear density of 30 tex, of which stainless steel filament accounts for 13.3%, fine cotton fiber accounts for 36.7%, and recycled cotton fiber accounts for 50%. The longitudinal structure of the covered yarn is as follows: Figure 4 As shown, the friction spinning process can effectively coat recycled cotton fibers onto the outer layer of the initial wrapped yarn. However, due to the relatively short length of the recycled cotton fibers, the fiber arrangement in the yarn is relatively loose, resulting in insufficient coating tightness. During weaving, the recycled cotton fibers are easily pulled out due to friction, affecting subsequent weaving processes. The cross-sectional microstructure of the coated yarn is shown in the figure. Figure 5 As shown, Figure 5 As can be seen from the red circle, the initial wrapping yarn is basically in the center of the covering yarn.

[0058] S3. The covered yarn obtained in S2 is spun again with a 630tex linear density fine cotton roving using ring spinning to produce a multi-layer composite electromagnetic shielding yarn, completing the third layer of covering. The process parameters for this step are: spindle speed 7000 r / min, twist coefficient 360, back zone draft ratio 1.2 times. The final product is a 45tex linear density composite electromagnetic shielding yarn containing recycled cotton fibers, in which stainless steel filament accounts for 8.9%, fine cotton fiber accounts for 57.8%, and recycled cotton fiber accounts for 33.3%. The longitudinal structure of the finished yarn is as follows. Figure 6 As shown, after ring spinning to coat the fine cotton fibers onto the outermost layer, the yarn surface is smooth, the fiber arrangement is more orderly than that of the coated yarn, the overall structure is stable, and a tight spiral winding structure is formed between the fibers. The yarn has a regular appearance and the fibers are firmly bonded together; the microscopic morphology of the cross-section of the finished yarn is as follows. Figure 7 As shown, Figure 7 As can be seen from the red circle, the stainless steel filament core is always in the center of the yarn, and the covering structure is complete and uniform.

[0059] The composite electromagnetic shielding yarn containing recycled cotton fibers prepared in this embodiment has the following advantages:

[0060] The yarn has a high coverage rate and excellent shielding performance; the yarn breaking strength is greater than 400cN, the breaking elongation is greater than 30mm, and the yarn evenness CV value is less than 7%, resulting in excellent overall performance; the yarn has less hairiness and uniform evenness, which is beneficial for subsequent weaving methods such as machine weaving and knitting; the production process is stable and reliable, suitable for industrial-scale production, and has strong economic efficiency and operability; it significantly improves the utilization efficiency of recycled cotton resources and meets the requirements of green manufacturing and sustainable development.

[0061] Example 2:

[0062] The basic content is the same as in Example 1, except that:

[0063] S1. Using 600tex linear density fine cotton roving and 3.5tex linear density stainless steel filament as raw materials, the yarn is spun using the Sirofil spinning process with the following parameters: spindle speed 5800 r / min, twist coefficient 340, and back zone draft ratio 1.4. The final yarn produced is a 14tex linear density initial cover yarn, of which stainless steel filament accounts for 25% and fine cotton fiber accounts for 75%.

[0064] S2. Recycled cotton raw materials are sequentially processed through opening and impurity removal, carding and web forming, and three drawing processes to obtain recycled cotton sliver. The process parameters are as follows: HFX-A0 small opening machine cylinder speed 400r / min, doffer speed 195r / min, feed line speed 0.68m / min; HFX-A1 small carding machine cylinder speed 380r / min, doffer speed 180r / min, feed line speed 0.095m / min; HFX-A2 small drawing machine first draw uses 5 slivers with a designed draft ratio of 4.5 times, second draw uses 3 slivers with a designed draft ratio of 3.5 times, and third draw uses 2 slivers with a designed draft ratio of 2.8 times; finally, a recycled cotton sliver with a linear density of 300tex is obtained.

[0065] Using the recycled cotton sliver and the initial wrapped yarn obtained in step S1 as raw materials, the yarn is wrapped and formed by friction spinning process. The process parameters are friction roller speed of 4200 r / min and combing roller speed of 3400 r / min. A wrapped yarn with a linear density of 28 tex is obtained, in which stainless steel filament accounts for 12%, fine cotton fiber accounts for 37%, and recycled cotton fiber accounts for 51%.

[0066] S3. Using the above-mentioned covered yarn and roving of fine cotton with a linear density of 600 tex as raw materials, the third layer of covering is completed by ring spinning process. The process parameters are spindle speed 6800 r / min, twist coefficient 350, and back zone draft ratio 1.1 times. Finally, a composite electromagnetic shielding yarn with a linear density of 44 tex containing recycled cotton fiber is obtained, in which stainless steel filament accounts for 8.5%, fine cotton fiber accounts for 58.5%, and recycled cotton fiber accounts for 33%.

[0067] The composite electromagnetic shielding yarn containing recycled cotton fiber prepared in this embodiment has a complete and unblemished core, and its shielding performance is stable. The measured yarn breaking strength is 420cN, breaking elongation is 32mm, and yarn evenness CV value is 6.8%. The yarn has little hairiness and uniform evenness, and can be adapted to various weaving methods such as machine weaving and knitting. The production process is stable and meets the requirements of industrial production.

[0068] Example 3:

[0069] The basic content is the same as in Example 1, except that:

[0070] S1. Using 650tex linear density fine cotton roving and 5tex linear density stainless steel filament as raw materials, the yarn is spun using the Sirofil spinning process with the following parameters: spindle speed 6200 r / min, twist coefficient 380, and back zone draft ratio 1.5. The final yarn produced is a 16tex linear density initial cover yarn, of which stainless steel filament accounts for 30% and fine cotton fiber accounts for 70%.

[0071] S2. Recycled cotton raw materials are sequentially processed through opening and impurity removal, carding and web forming, and three drawing processes to obtain recycled cotton sliver. The process parameters are as follows: HFX-A0 small opening machine cylinder speed 430r / min, doffer speed 220r / min, feed line speed 0.75m / min; HFX-A1 small carding machine cylinder speed 420r / min, doffer speed 205r / min, feed line speed 0.11m / min; HFX-A2 small drawing machine first draw uses 3 slivers with a designed draft ratio of 3.2, second draw uses 2 slivers with a designed draft ratio of 2.5, and third draw uses 2 slivers with a designed draft ratio of 2.2; finally, a recycled cotton sliver with a linear density of 400tex is obtained.

[0072] Using the above-mentioned recycled cotton sliver and the initial wrapped yarn obtained in step S1 as raw materials, the yarn is wrapped and formed by friction spinning process. The process parameters are friction roller speed of 4400 r / min and combing roller speed of 3600 r / min. A wrapped yarn with a linear density of 32 tex is obtained, in which stainless steel filament accounts for 14%, fine cotton fiber accounts for 35%, and recycled cotton fiber accounts for 51%.

[0073] S3. Using the above-mentioned covered yarn and 650tex fine cotton roving as raw materials, the third layer of covering is completed by ring spinning process. The process parameters are spindle speed 7200r / min, twist coefficient 370, and back zone draft ratio 1.3 times. Finally, a multi-layer composite electromagnetic shielding yarn with a linear density of 46tex is obtained, in which stainless steel filament accounts for 9.5%, fine cotton fiber accounts for 57.5%, and recycled cotton fiber accounts for 33%.

[0074] The composite electromagnetic shielding yarn containing recycled cotton fiber prepared in this embodiment has complete coverage without any missing core, and has excellent shielding performance. The measured yarn breaking strength is 450cN, breaking elongation is 35mm, and yarn evenness CV value is 6.5%. The yarn structure is compact and the surface is smooth. It can be adapted to various weaving methods such as machine weaving and knitting. It has a high process error tolerance and the production process is stable and controllable, meeting the requirements of industrial-scale production.

[0075] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers, characterized in that: The preparation method includes the following steps: S1. Stainless steel filament and roving are spun using ring spinning process, so that the roving is stretched to form roving fibers that cover the outer periphery of stainless steel filament, thus producing initial wrapped yarn. S2. The primary wrapped yarn and the recycled cotton sliver are spun using a friction spinning process, so that the recycled cotton fibers formed after the recycled cotton sliver is combed cover the outer periphery of the primary wrapped yarn to obtain a covered yarn. S3. The covered yarn and the roving of fine cotton are spun using a ring spinning process, so that the fine cotton fibers formed after the roving of fine cotton are drawn and covered on the outer periphery of the covered yarn, to obtain a composite electromagnetic shielding yarn containing recycled cotton fibers.

2. The method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers according to claim 1, characterized in that: In step S1, the linear density of the fine cotton roving is 600 tex-650 tex, and the linear density of the stainless steel filament is 3 tex-5 tex. The ring spinning process is Sirofil spinning, with the following process parameters: spindle speed of 5800 r / min-6200 r / min, twist coefficient of 340-380, and back zone draft ratio of 1.4-1.

6.

3. The method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers according to claim 2, characterized in that: In step S1, the linear density of the initial wrapped yarn is 14 tex-16 tex, wherein the mass percentage of stainless steel filament is 25%-30% and the mass percentage of fine cotton fiber is 70%-75%.

4. A method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers according to claim 1, 2, or 3, characterized in that: In step S2, the method for preparing the recycled cotton sliver includes the following steps: first, the recycled cotton raw material is placed in an opening machine to open and remove impurities to obtain a recycled cotton fiber layer; then, the recycled cotton fiber layer is fed into a carding machine to form a recycled cotton fiber web; finally, the recycled cotton fiber web is drawn through a drawing frame to obtain a recycled cotton sliver.

5. The method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers according to claim 4, characterized in that: In the opening and impurity removal process, the cylinder speed of the opening machine is 400 r / min-430 r / min, the doffer speed is 200 r / min-215 r / min, and the feed line speed is 0.70 m / min-0.75 m / min; in the carding process, the cylinder speed of the carding machine is 380 r / min-420 r / min, the doffer speed is 180 r / min-200 r / min, and the feed line speed is 0.09 m / min-0.11 m / min; in the drawing process, the first drawing uses 3-5 slivers combined with a draft ratio of 3.5-4.5, and the second and third drawing both use 2-4 slivers combined with a draft ratio of 2.5-3.5; the linear density of the resulting recycled sliver is 300 tex-400 tex.

6. A method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers according to claim 1, 2, or 3, characterized in that: In step S2, the process parameters for friction spinning are: the rotation speed of the friction roller is 2700 r / min to 5100 r / min, and the rotation speed of the combing roller is 2500 r / min to 4000 r / min.

7. A method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers according to claim 1, 2, or 3, characterized in that: In step S2, the linear density of the resulting covered yarn is 28 tex-32 tex, wherein the mass percentage of stainless steel filament is 12%-14%, the mass percentage of fine cotton fiber is 35%-37%, and the mass percentage of recycled cotton fiber is 49%-51%.

8. A method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers according to claim 1, 2, or 3, characterized in that: In step S3, the process parameters for ring spinning are: spindle speed of 6800 r / min-7200 r / min, twist coefficient of 350-370, and back zone draft ratio of 1.1-1.

3.

9. The method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers according to claim 4, characterized in that: In step S3, the linear density of the composite electromagnetic shielding yarn containing recycled cotton fiber is 44 tex-46 tex, wherein the mass percentage of stainless steel filament is 8.5%-9.5%, the mass percentage of fine cotton fiber is 57.5%-58.5%, and the mass percentage of recycled cotton fiber is 32%-34%.

10. A yarn, characterized in that: The yarn is prepared by the method for preparing a composite electromagnetic shielding yarn containing recycled cotton fibers as described in claim 1, 2 or 3. The yarn has a three-layer composite structure consisting of a stainless steel filament core, a fine cotton inner layer, a recycled cotton middle layer, and a fine cotton outer layer, from the inside out.

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