A combined knitting process of face bottom yarn layer changing jacquard and filling yarn back wefting

Abstract

The application relates to the technical field of knitted fabric, in particular to a composite knitting process of face bottom yarn layer-changing jacquard and filling yarn interlining. The process comprises the following steps: S1, pretreating face yarn, bottom yarn and filling yarn; S2, face bottom yarn layer-changing jacquard knitting; S3, synchronously feeding face yarn and bottom yarn through an interlining yarn guide, feeding filling yarn into the needle back gap before the knitting needle is withdrawn, clamping the filling yarn between the sinking arc of the face yarn and the bottom yarn with the knitting needle descending, and forming an air layer; S4, within 0.4-0.6 seconds after the layer changing is completed, controlling the knitting needle to reset to the normal jacquard position of S201 by an electronic needle selector, restoring the filling yarn feeding speed to the setting of S201, repeating steps S2-S3 until the whole piece of fabric is knitted; and S5, post-processing. The application provides the composite knitting process of face bottom yarn layer-changing jacquard and filling yarn interlining, so as to solve the problems of low production efficiency and unstable air layer caused by step-by-step implementation of jacquard and interlining in the prior art.

Description

Technical Field

[0001] This application relates to the field of knitted fabric technology, and in particular to a composite knitting process of alternating face and base yarns in jacquard weft and filling yarns in weft. Background Technology

[0002] Knitted fabrics, due to their softness, elasticity, and shapeability, are widely used in clothing, home textiles, and outdoor protective applications. In existing technologies, jacquard weaving primarily uses electronic needle selection to control the looping of single or double yarns to create patterns. Face and back yarn swapping jacquard technology allows for independent double-sided pattern designs by dynamically alternating the positions of the face and back yarns, satisfying personalized aesthetic needs. Filler yarn weft insertion technology uses weft-direction filler yarns to construct a fabric sandwich structure, significantly improving the fabric's warmth, crispness, and deformation resistance. The combined technology overcomes the limitations of traditional knitted fabrics, which often suffer from a single appearance and lack of functionality.

[0003] However, current composite processes have significant shortcomings in raw material selection and adaptation design. For example, the jacquard process for changing the face and back yarns often uses single-material yarns such as pure cotton or conventional polyester staple fiber, relying on Siro spinning or ring spinning processes for preparation. Layer changing is achieved through a fixed needle path and electronic needle selector, resulting in unstable air layers and low production efficiency. The filling yarn weft insertion process mainly uses 200D-400D conventional polyester filaments, employing simple network treatment to improve anti-spinning ability. It is fed into the fabric interlayer through a fixed yarn guide device, which is prone to spin-through due to tension fluctuations during layer changing during weaving. At the same time, flame retardant function and structural design are difficult to coordinate. Existing technologies often adopt a step-by-step process, that is, completing jacquard weaving first and then impregnating flame retardant. This not only results in low production efficiency, but also makes the air layer structure prone to collapse due to high-temperature baking during finishing. As a result, it is difficult to balance process stability, fabric performance and scene adaptability, thus restricting the industrial application of the technology. Summary of the Invention

[0004] This application provides a composite knitting process that involves alternating layers of face and base yarns in jacquard weft and inserting weft yarns in filling yarns, in order to solve the problems mentioned in the background art.

[0005] Firstly, a composite knitting process is provided, which involves alternating layers of face and base yarns in jacquard weft weaving and filling yarn weft insertion, comprising: S1. Pre-treat the outer yarn, base yarn, and filling yarn; S2, Jacquard weaving with alternating layers of top and bottom yarns: S201, the front needle bed feeds the face yarn and the rear needle bed feeds the bottom yarn, and a weft guide for the filling yarn is set between the two needle beds; the distance between the needle beds is adjusted to 4~6mm, and the initial position of the sinker is 8~10mm from the center of the needle cylinder; S202: The electronic needle selector controls the front needle bed needles to rise to a high position of 14-16mm to form a loop, and the face yarn forms a jacquard pattern on the surface of the fabric; the rear needle bed needles are kept at a low position of 4-6mm, and the bottom yarn forms the bottom float. S203. When knitting reaches the layer change needle position, the electronic needle selector switches control, causing the back needle bed needles to rise to a high position of 14-16mm to form loops, allowing the base yarn to pass over the face yarn and show color on the fabric surface; the front needle bed needles descend to a low position of 4-6mm to form tucking loops, preventing the face yarn from covering the base yarn color; during the layer change process, the filling yarn feeding speed is temporarily increased by 4-5%; S3. The weft guide feeds yarn synchronously with the face yarn and the base yarn. Before the knitting needles retract, the filling yarn is fed into the needle back gap and is clamped between the sinking arc of the face yarn and the base yarn as the knitting needles descend, forming an air layer. The filling yarn weft guide feeds yarn at a padding yarn ratio of 1:2, forming a suspension arc every 3 needles, and the sinker advances 1.8~2.2mm toward the center of the needle cylinder; S4. After the layer change is completed, within 0.4~0.6s, the electronic needle selector controls the knitting needle to return to the normal jacquard position of S201, and the filling yarn feeding speed is restored to the initial setting of S201. Repeat steps S2~S3 until the entire fabric is knitted. S5. Perform post-processing.

[0006] Preferably, in step S203, the needle spacing for changing layers is set to 8-12 needles, and the rising speed of the needles on the rear needle bed is consistent with the falling speed of the needles on the front needle bed during layer changing.

[0007] Preferably, in S3, the guiding angles of the weft yarn guide, face yarn guide, and bottom yarn guide are the same and are 28~32°. The guiding angle refers to the angle between the center line of the yarn outlet of the guide and the axis of the needle bar.

[0008] Preferably, in S3, the thickness of the air layer is 0.9~1.1mm.

[0009] Preferably, the pretreatment steps for the outer yarn, base yarn, and filling yarn include: The face yarn, base yarn, and filling yarn are pre-dried in hot air at 80℃ for 30 minutes, and then placed in an environment of 20±2℃ and 65% relative humidity for 24 hours to equilibrate. At the same time, a magnetic tensioner is used to set the tension, and the tension sensor provides real-time feedback and adjustment so that the tension of the face yarn is 28~32cN, the tension of the base yarn is 33~37cN, and the tension of the filling yarn is 18~22cN.

[0010] Preferably, the veil preparation process includes the following steps: The basic material fibers, aramid and acrylonitrile fibers are mixed in a certain proportion to make yarn. The yarn is immersed in yarn sol at 55~60℃ for 1~2 hours, and then dried at 75~80℃ for 1.5~2 hours to obtain the yarn. The method for preparing the veil sol is as follows: Tetrabutyl titanate, anhydrous ethanol, and deionized water were mixed in a volume ratio of (0.5~1):5:2. Then, chitin (2% by weight of deionized water) was added, and glacial acetic acid was added to adjust the pH to 3~4. The mixture was stirred for 25~30 minutes to form a sol. The linear density of the veil is set to 16 tex.

[0011] Preferably, the ratio of the base material, aramid fiber, and acrylonitrile fiber is 6:3:1; The base material is selected from one of polyester, nylon, polyethylene, bamboo fiber, and modal. The aramid is selected from either aramid 1313 or aramid 1414.

[0012] Preferably, the base yarn is selected from at least one of flame-retardant viscose and aramid.

[0013] Preferably, the filling yarn is prepared by: making yarn from aerogel composite fiber and spandex through core-spun process, with a linear density of 12 tex, and the ratio of aerogel composite fiber to spandex is 4:(0.8~1.2). The method for preparing the aerogel composite fiber is as follows: Tetraethyl orthosilicate, ethanol, and deionized water were mixed in a volume ratio of (3-4):8:1. A 0.1 mol / L hydrochloric acid solution was added as a catalyst, along with 5% (by mass) tea saponin (by mass of deionized water). The mixture was stirred in a 50°C water bath for 1.5-2 hours to form a uniform and transparent composite sol. The mass of the hydrochloric acid solution was 0.3-0.5% of the mass of tetraethyl orthosilicate. Lanolin was added to the composite sol and mixed evenly. Then, titanium dioxide nanoparticles with a particle size of 20 nm were added. After stirring continuously for 0.5 to 1 h, the mixture was allowed to stand in a sealed container at 60 °C for 22 to 24 h to complete gelation, resulting in a wet gel. The mass of lanolin was 1.5 to 2% of the mass of the composite sol, and the mass of titanium dioxide nanoparticles was 4 to 5% of the mass of the composite sol. The wet gel was frozen at room temperature to -40°C, and then dried under vacuum of 10 Pa at -30°C for 46-48 hours to obtain an aerogel. After the aerogel is crushed, it is mixed with polyamide chips at a mass ratio of 4:1, and melt-spun at 260~280℃. The aerogel composite fiber is then obtained by stretching and winding.

[0014] Preferably, the draw ratio is 3.5.

[0015] The beneficial effects of the technical solution provided in this application include: This application provides a composite knitting process involving jacquard weft insertion and filling yarn layering. This process ensures the base yarn precisely passes over the face yarn to form loops, and the face yarn is pressed into low-position loops, effectively preventing the base yarn color from being covered and improving pattern clarity. Furthermore, by controlling the tension of the face and base yarns, it prevents yarn slack or breakage during layering. The weft insertion guide feeds the yarn synchronously with the face and base yarns, and through a 1:2 yarn padding ratio and precise advancement with sinkers, the filling yarn is stably held between the sinker arcs of the face and base yarn loops, forming an air layer of a certain thickness. This reduces the thermal conductivity coefficient and enhances warmth. Simultaneously, the filling yarn feeding speed is temporarily increased during layering to compensate for tension fluctuations and prevent air layer breakage. The filling yarn does not require secondary embedding; weft insertion is completed directly during the knitting process. By separately treating the face yarn, base yarn, and filling yarn, the post-finish flame-retardant process is eliminated, preventing air layer structure collapse and jacquard pattern deformation. This reduces the risk of fabric deformation and process time, requires no special equipment modification, has low equipment investment costs, can be quickly applied to existing production lines, and has a wide range of applications. Meanwhile, in the composite knitting process of changing the face and bottom yarns and inserting the filling yarns weft provided in this application, multiple materials are composited and modified. The aramid in the face yarn has strong wear resistance. When the acrylonitrile fiber is heated, it releases hydrogen chloride gas to form a flame-retardant barrier and forms an expanded carbon layer with the chitin in the face yarn sol. Combined with the aerogel composite fiber and spandex in the filling yarn, the air layer structure formed together ensures both warmth and breathability. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A process flow diagram of the composite knitting process of changing the face and base yarns in jacquard and inserting the filling yarns in this application; Figure 2 The process flow diagram of S2 in the composite knitting process of changing the face and bottom yarns for jacquard weft and filling yarn weft provided in this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] See Figure 1 and Figure 2 As shown, this application provides a composite knitting process in which the face and base yarns are interchanged in jacquard weft and the filling yarns are interlining weft.

[0020] Example 1 The composite knitting process of changing the face and base yarns in jacquard weft and inserting the filling yarns provided in this embodiment includes the following steps: S1. Pre-treat the outer yarn, base yarn, and filling yarn: The face yarn, base yarn, and filling yarn are wound separately onto a yarn tube and pre-dried in an 80℃ hot air setting machine for 30 minutes (wind speed 1.5m / s). Then, they are placed in an environment of 20℃ and 65% relative humidity for 24 hours to equilibrate. At the same time, a magnetic tensioner is used to set the tension, and the tension sensor provides real-time feedback and adjustment to make the face yarn tension 30cN, the base yarn tension 35cN, and the filling yarn tension 20cN (with fluctuation deviations ≤±1cN).

[0021] S2, Jacquard weaving with alternating layers of top and bottom yarns: S201, the front needle bed feeds the face yarn and the rear needle bed feeds the bottom yarn. A filling yarn weft guide is set between the two needle beds. The guiding angle of the filling yarn guide, the face yarn guide and the bottom yarn guide is set to 30°. The filling yarn feeding motor speed is 120r / min. The needle bed spacing is adjusted to 5mm. The initial position of the sinker is 10mm away from the center of the needle cylinder. S202, the electronic needle selector controls the front needle bed needles to rise to a high position of 15mm to form a loop, hook the face yarn and complete the loop formation, so that the face yarn forms a jacquard pattern on the surface of the fabric; the rear needle bed needles are kept at a low position of 5mm, and the bottom yarn forms the bottom layer float. S203. Each layer change cycle consists of 10 stitches. When knitting reaches the layer change needle position, the electronic needle selector switches control, causing the back needle bed needles to rise at a speed of 20mm / s to a high position of 15mm to form a loop. The base yarn (back needle bed yarn guide) moves forward by 0.5mm, inserting the base yarn into the needle hook and forming a loop. At the same time, the front needle bed needles descend at a speed of 20mm / s to a low position of 5mm, and the face yarn forms a tuck loop with a tuck loop height of 3mm to prevent the face yarn from covering the color of the base yarn. During the layer change process, the filling yarn feeding speed is temporarily increased by 5% to compensate for the yarn tension fluctuations during the layer change. The layer change needle position interval is 10 stitches.

[0022] S3. The weft guide maintains a 1:1 synchronous yarn feeding ratio with the face yarn and the base yarn (i.e., the weft guide completes one yarn feeding for every row of knitting). 0.3s before the knitting needles retract, the filler yarn is fed into the needle back gap (the yarn feeding position is 2mm away from the needle hook, calibrated by the position sensor of the guide). As the knitting needles descend, the filler yarn is clamped between the sinking arc of the face yarn and the base yarn, forming a 1mm air layer. The filling yarn weft guide feeds yarn at a yarn-to-pad ratio of 1:2, forming a suspension arc every 3 needles, and the sinker advances 2mm toward the center of the needle cylinder.

[0023] The specific implementation method of the 1:2 filling yarn ratio is as follows: the length of yarn fed into the filling yarn for each loop cycle corresponds to the loop interval of 2 needles, that is, the first needle is fed yarn, the second needle is fed without yarn, and the third needle is fed yarn, forming a regular hanging arc, and the length of the hanging arc is controlled within 3mm.

[0024] The sinker is pushed 2.0 mm toward the center of the syringe with a pressure of 0.8 N (calibrated by the sinker pressure sensor), which tightly clamps the filling yarn between the coil sinker arcs of the face yarn and the back yarn, forming an air layer with a thickness of 1 mm.

[0025] S4. Within 0.5 seconds after the layer change is completed, the electronic needle selector controls the knitting needles to reset to the normal jacquard position of S201. The filling yarn feeding speed returns to the initial setting of S201. Repeat steps S2 to S3 until the entire fabric is knitted. The flat knitting machine speed is set to 80 r / min. After knitting to the preset length of 100 meters (width 1.54m), the machine automatically stops, completing the knitting of the entire fabric.

[0026] S5. Perform post-processing.

[0027] A relaxation pre-shrinking machine was used, with a set temperature of 85℃, a processing time of 15 minutes, and a machine speed of 20 m / min, to pre-shrink and shape the woven fabric. The shrinkage rate was controlled at 2.5%. Then, it was sent to a 60℃ hot air dryer to dry for 30 minutes to complete the pre-shrinking and shaping.

[0028] The width before pre-shrinking is 1.54m, and the width after pre-shrinking is 1.5m, which meets the requirements.

[0029] Furthermore, in this embodiment, the yarn is a 16tex single yarn with a twist of 450T / m (S-twist) and a diameter of 0.18mm. Its preparation process is as follows: Polyester, aramid 1313 and acrylonitrile fiber in a mass ratio of 6:3:1 were mixed to make yarn (16tex). The yarn was immersed in yarn sol at 55°C for 2 hours (the yarn sol should cover the yarn). After being removed, it was dried at 75°C for 1.5 hours to obtain the yarn. The method for preparing the veil sol is as follows: Tetrabutyl titanate, anhydrous ethanol, and deionized water were mixed in a volume ratio of 1:5:2. Then, chitosan (2% by weight of deionized water) was added, and glacial acetic acid was added to adjust the pH to 4. The mixture was stirred for 25 minutes to form a sol. In this example, 20 mL of tetrabutyl titanate, 100 mL of anhydrous ethanol, and 40 mL of deionized water were used.

[0030] The base yarn is made of flame-retardant viscose fiber (purchased from Hangzhou Youbiao Textile), and is spun into 20tex single yarn by friction spinning process, with a twist of 420T / m (S twist) and a diameter of 0.22mm.

[0031] The filling yarn is made into 12tex core-spun yarn with a diameter of 0.16mm through core-spun spinning process. The specific preparation process is as follows: aerogel composite fiber and spandex are made into yarn through core-spun spinning process, with a linear density of 12tex and a ratio of aerogel composite fiber to spandex of 4:1. The preparation method of aerogel composite fiber is as follows: Tetraethyl orthosilicate, ethanol, and deionized water were mixed in a volume ratio of 3:8:1. A 0.1 mol / L hydrochloric acid solution was added as a catalyst, along with 5% (by mass) of tea saponin (by mass of deionized water). The mixture was stirred in a 50°C water bath for 2 hours to form a uniform and transparent composite sol. The mass of the hydrochloric acid solution was 0.4% of the mass of tetraethyl orthosilicate. Lanolin was added to the composite sol and mixed evenly. Then, titanium dioxide nanoparticles with a particle size of 20 nm were added. After stirring continuously for 1 h, the mixture was allowed to stand in a sealed container at 60 °C for 24 h to complete gelation, resulting in a wet gel. The mass of lanolin was 2% of the mass of the composite sol, and the mass of titanium dioxide nanoparticles was 5% of the mass of the composite sol. The wet gel was frozen at room temperature to -40°C, and then dried under vacuum of 10 Pa at -30°C for 48 h to obtain an aerogel. After the aerogel is crushed, it is mixed with polyamide chips (nylon 56 chips) at a mass ratio of 4:1, melt-spun at 270℃, and then drawn (drawing ratio of 3.5) and wound to obtain aerogel composite fibers.

[0032] The abrasion resistance of the fabric was tested using the Martindale method, with an abrasion rate ≤3% and an abrasion resistance of ≥5000 cycles. The thermal conductivity was tested according to GB / T 10295-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials - Heat Flow Meter Method", with a thermal conductivity ≤0.028 W / (m²). K); Referring to the test of GB / T 5455-2014 "Determination of vertical damage length, smoldering and afterflame time of textiles", the fabric has an afterflame time of 1.5s, a flame retardant time of 2.0s, and a damage length of 72mm, which meets the Class B requirements of GB 8965.1-2020 "Flame Retardant Protection of Protective Clothing".

[0033] Example 2 The composite knitting process of changing the face and base yarns in jacquard weft and inserting the filling yarns provided in this embodiment includes the following steps: S1. Pre-treat the outer yarn, base yarn, and filling yarn: The face yarn, base yarn, and filling yarn are wound separately onto a yarn tube and pre-dried in an 80℃ hot air setting machine for 30 minutes (wind speed 1.5m / s). Then, they are placed in an environment of 22℃ and 65% relative humidity for 24 hours to equilibrate. At the same time, a magnetic tensioner is used to set the tension, and the tension sensor provides real-time feedback and adjustment to make the face yarn tension 28cN, the base yarn tension 33cN, and the filling yarn tension 18cN (with fluctuation deviations ≤±1cN).

[0034] S2, Jacquard weaving with alternating layers of top and bottom yarns: S201, the front needle bed corresponds to the feeding of the face yarn, and the rear needle bed corresponds to the feeding of the bottom yarn. A filling yarn weft guide is set between the two needle beds. The guiding angle of the weft guide, face yarn guide, and bottom yarn guide is set to 28°. The filling yarn feeding motor speed is 120r / min, the needle bed spacing is adjusted to 4mm, and the initial position of the sinker is 8mm from the center of the needle cylinder. S202, the electronic needle selector controls the front needle bed needles to rise to a high position of 14mm to form a loop, hook the face yarn and complete the loop formation, so that the face yarn forms a jacquard pattern on the surface of the fabric; the rear needle bed needles are kept at a low position of 4mm, and the bottom yarn forms the bottom layer float. S203. Each layer change cycle consists of 10 stitches. When knitting reaches the layer change needle position, the electronic needle selector switches control, causing the back needle bed needles to rise at a speed of 20mm / s to a high position of 14mm to form a loop. The base yarn (back needle bed yarn guide) moves forward by 0.5mm, inserting the base yarn into the needle hook and forming a loop. At the same time, the front needle bed needles descend at a speed of 20mm / s to a low position of 4mm, and the face yarn forms a tuck loop with a tuck loop height of 3mm to prevent the face yarn from covering the color of the base yarn. During the layer change process, the filling yarn feeding speed is temporarily increased by 4% to compensate for the yarn tension fluctuations during the layer change. The layer change needle position interval is 8 stitches.

[0035] S3. The weft guide maintains a 1:1 synchronous yarn feeding ratio with the face yarn and the base yarn (i.e., the weft guide completes one yarn feeding for every row of knitting). 0.3 seconds before the knitting needles retract, the filler yarn is fed into the needle back gap (the yarn feeding position is 2mm away from the needle hook, calibrated by the position sensor of the guide). As the knitting needles descend, the filler yarn is clamped between the sinking arc of the face yarn and the base yarn, forming a 0.9mm air layer. The filling yarn weft guide feeds yarn at a yarn-to-pad ratio of 1:2, forming a suspension arc every 3 needles, and the sinker advances 1.8mm toward the center of the needle cylinder.

[0036] The specific implementation method of the 1:2 filling yarn ratio is as follows: the length of yarn fed into the filling yarn for each loop cycle corresponds to the loop interval of 2 needles, that is, the first needle is fed yarn, the second needle is fed without yarn, and the third needle is fed yarn, forming a regular hanging arc, and the length of the hanging arc is controlled within 3mm.

[0037] The sinker is pushed 1.8 mm toward the center of the syringe with a pressure of 0.8 N (calibrated by the sinker pressure sensor), which tightly clamps the filling yarn between the coil sinker arcs of the face yarn and the back yarn, forming an air layer with a thickness of 0.9 mm.

[0038] S4. Within 0.5 seconds after the layer change is completed, the electronic needle selector controls the knitting needles to reset to the regular jacquard position of S201, and the filling yarn feeding speed returns to the initial setting. Repeat steps S2 to S3 until the entire fabric is knitted. The flat knitting machine speed is set to 80 r / min. After knitting to the preset length of 100 meters (width 1.54m), the machine automatically stops, completing the knitting of the entire fabric.

[0039] S5. Perform post-processing.

[0040] A relaxation pre-shrinking machine was used, with a set temperature of 85℃, a processing time of 15 minutes, and a machine speed of 20 m / min, to pre-shrink and shape the woven fabric. The shrinkage rate was controlled at 2.5%. Then, it was sent to a 60℃ hot air dryer to dry for 30 minutes to complete the pre-shrinking and shaping.

[0041] The width before pre-shrinking is 1.54m, and the width after pre-shrinking is 1.5m, which meets the requirements.

[0042] Furthermore, in this embodiment, the yarn is a 16tex single yarn with a twist of 450T / m (S-twist) and a diameter of 0.18mm. Its preparation process is as follows: Nylon, aramid 1414 and acrylonitrile fiber in a mass ratio of 6:3:1 were mixed to make yarn (16tex). The yarn was immersed in yarn sol at 60°C for 1 hour (the sol should cover the yarn). After being removed, it was dried at 80°C for 2 hours to obtain the yarn. The method for preparing the veil sol is as follows: Tetrabutyl titanate, anhydrous ethanol, and deionized water were mixed in a volume ratio of 0.5:5:2. Then, chitosan (2% by weight of deionized water) was added, and glacial acetic acid was added to adjust the pH to 3. The mixture was stirred for 30 minutes to form a sol. In this example, 20 mL of tetrabutyl titanate, 200 mL of anhydrous ethanol, and 80 mL of deionized water were used.

[0043] The base yarn is made of aramid fiber and spun into 20tex single yarn using a friction spinning process. The twist is 420T / m (S twist) and the diameter is 0.22mm.

[0044] The filling yarn is made into 12tex core-spun yarn through a core-spun spinning process. The specific preparation process is as follows: aerogel composite fiber and spandex are made into yarn through a core-spun spinning process. The linear density is 12tex and the diameter is 0.16mm. The ratio of aerogel composite fiber to spandex is 4:1.2. The preparation method of aerogel composite fiber is as follows: Tetraethyl orthosilicate, ethanol, and deionized water were mixed in a volume ratio of 4:8:1. A 0.1 mol / L hydrochloric acid solution was added as a catalyst, along with 5% (by mass) tea saponin (by mass of deionized water). The mixture was stirred in a 50°C water bath for 1.5 h to form a uniform and transparent composite sol. The mass of the hydrochloric acid solution was 0.5% of the mass of tetraethyl orthosilicate. Lanolin was added to the composite sol and mixed evenly. Then, titanium dioxide nanoparticles with a particle size of 20 nm were added. After stirring continuously for 0.5 h, the mixture was allowed to stand in a sealed container at 60 °C for 23 h to complete gelation, resulting in a wet gel. The mass of lanolin was 1.5% of the mass of the composite sol, and the mass of titanium dioxide nanoparticles was 4% of the mass of the composite sol. The wet gel was frozen at room temperature to -40°C, and then dried under vacuum of 10 Pa at -30°C for 46 h to obtain an aerogel. After the aerogel is crushed, it is mixed with polyamide chips (nylon 56 chips) at a mass ratio of 4:1, melt-spun at 260℃, and then drawn (drawing ratio of 3.5) and wound to obtain aerogel composite fibers.

[0045] The abrasion resistance of the fabric was tested using the Martindale method, with an abrasion rate ≤3% and an abrasion resistance of ≥5000 cycles. The thermal conductivity was tested according to GB / T 10295-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials - Heat Flow Meter Method", with a thermal conductivity ≤0.033 W / (m²). K); Referring to the test of GB / T 5455-2014 "Determination of vertical damage length, smoldering and afterflame time of textiles", the fabric has an afterflame time of 1.5s, a flame retardant time of 2.6s, and a damage length of 79mm, which meets the Class B requirements of GB 8965.1-2020 "Flame Retardant Protection of Protective Clothing".

[0046] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A composite knitting process involving alternating layers of face and base yarns in jacquard weft weft weft yarns, characterized in that, The composite knitting process includes: S1. Pre-treat the outer yarn, base yarn, and filling yarn; S2, jacquard weaving with alternating layers of top and bottom yarns; S3. The weft guide feeds yarn synchronously with the face yarn and the base yarn. Before the knitting needles retract, the filling yarn is fed into the needle back gap and is clamped between the sinking arc of the face yarn and the base yarn as the knitting needles descend, forming an air layer. The filling yarn weft guide feeds yarn at a padding yarn ratio of 1:2, forming a suspension arc every 3 needles, and the sinker advances 1.8~2.2mm toward the center of the needle cylinder; S4. After the layer change is completed, within 0.4~0.6s, the electronic needle selector controls the knitting needle to return to the normal jacquard position of S201, and the filling yarn feeding speed is restored to the setting of S201. Repeat steps S2~S3 until the entire fabric is knitted. S5. Perform post-processing; In step S1, the fabrication process of the veil includes the following steps: The basic material fibers, aramid and acrylonitrile fibers are mixed in a certain proportion to make yarn. The yarn is immersed in yarn sol at 55~60℃ for 1~2 hours, and then dried at 75~80℃ for 1.5~2 hours to obtain the yarn. The method for preparing the veil sol is as follows: Tetrabutyl titanate, anhydrous ethanol, and deionized water were mixed in a volume ratio of (0.5~1):5:

2. Then, chitin (2% by weight of deionized water) was added, and glacial acetic acid was added to adjust the pH to 3~4. The mixture was stirred for 25~30 minutes to form a veil sol.

2. The composite knitting process of alternating face and base yarn jacquard and filling yarn weft insertion as described in claim 1, characterized in that, S2 includes: S201, the front needle bed feeds the face yarn and the rear needle bed feeds the bottom yarn, and a filling yarn weft guide is provided between the two needle beds; The needle bed spacing is adjusted to 4-6mm, and the initial position of the sinker is 8-10mm from the center of the syringe. S202, the electronic needle selector controls the front needle bed needles to rise to a high position of 14~16mm to form a loop, and the yarn forms a jacquard pattern on the surface of the fabric. The needles on the back needle bed are kept at a low position of 4-6mm, and the bottom yarn forms the bottom layer float; S203. When knitting reaches the layer change needle position, the electronic needle selector switches the control, causing the back needle bed needles to rise to a high position of 14~16mm to form a loop, and the bottom yarn passes over the face yarn to show color on the surface of the fabric. The front needle bed needles descend to a low position of 4-6mm to form a tuck loop, preventing the face yarn from covering the color of the base yarn; During the layer change process, the filling yarn feeding speed is increased by 4-5%.

3. The composite knitting process of alternating face and base yarn jacquard and filling yarn weft insertion as described in claim 2, characterized in that: In S203, the needle spacing for changing layers is set to 8-12 needles, and the rising speed of the needles on the rear needle bed is consistent with the falling speed of the needles on the front needle bed during layer changing.

4. The composite knitting process of alternating face and base yarn jacquard and filling yarn weft insertion as described in claim 1, characterized in that: In S3, the guiding angles of the weft yarn guide, face yarn guide, and bottom yarn guide are the same and are 28~32°. The guiding angle refers to the angle between the center line of the yarn outlet of the guide and the axis of the needle bar.

5. The composite knitting process of alternating face and base yarns in jacquard weft weft weft insertion as described in claim 1, characterized in that: In S3, the thickness of the air layer is 0.9~1.1mm.

6. The composite knitting process of alternating face and base yarn jacquard and filling yarn weft insertion as described in claim 1, characterized in that: The pretreatment steps for the outer yarn, base yarn, and filling yarn include: The face yarn, base yarn, and filling yarn are pre-dried in hot air at 80℃ for 30 minutes, and then placed in an environment of 20±2℃ and 65% relative humidity for 24 hours to equilibrate. At the same time, a magnetic tensioner is used to set the tension, and the tension sensor provides real-time feedback and adjustment so that the tension of the face yarn is 28~32cN, the tension of the base yarn is 33~37cN, and the tension of the filling yarn is 18~22cN.

7. The composite knitting process of alternating face and base yarn jacquard and filling yarn weft insertion as described in claim 1, characterized in that: The ratio of the base material, aramid, and acrylic fiber is 6:3:1; The base material is selected from one of polyester, nylon, polyethylene, bamboo fiber, and modal. The aramid is selected from either aramid 1313 or aramid 1414.

8. The composite knitting process of alternating face and base yarn jacquard and filling yarn weft insertion as described in claim 1, characterized in that: The base yarn is selected from at least one of flame-retardant viscose and aramid.

9. The composite knitting process of alternating face and base yarn jacquard and filling yarn weft insertion as described in claim 1, characterized in that: The filling yarn is prepared by: making yarn from aerogel composite fiber and spandex through core-spun process, with a linear density of 12 tex, and the ratio of aerogel composite fiber to spandex is 4:(0.8~1.2). The method for preparing the aerogel composite fiber is as follows: Tetraethyl orthosilicate, ethanol, and deionized water were mixed in a volume ratio of (3-4):8:

1. A 0.1 mol / L hydrochloric acid solution was added as a catalyst, along with 5% (by mass) tea saponin (by mass of deionized water). The mixture was stirred in a 50°C water bath for 1.5-2 hours to form a uniform and transparent composite sol. The mass of the hydrochloric acid solution was 0.3-0.5% of the mass of tetraethyl orthosilicate. Lanolin was added to the composite sol and mixed evenly. Then, titanium dioxide nanoparticles with a particle size of 20 nm were added. After stirring continuously for 0.5 to 1 h, the mixture was allowed to stand in a sealed container at 60 °C for 22 to 24 h to complete gelation, resulting in a wet gel. The mass of lanolin was 1.5 to 2% of the mass of the composite sol, and the mass of titanium dioxide nanoparticles was 4 to 5% of the mass of the composite sol. The wet gel was frozen at room temperature to -40°C, and then dried under vacuum of 10 Pa at -30°C for 46-48 hours to obtain an aerogel. After the aerogel is crushed, it is mixed with polyamide chips at a mass ratio of 4:1, and melt-spun at 260~280℃. The aerogel composite fiber is then obtained by stretching and winding.

10. The composite knitting process of alternating face and base yarn jacquard and filling yarn weft insertion as described in claim 9, characterized in that: The stretching ratio is 3.5.

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