Production process and equipment of knitted fabric waterproof and breathable fabric by small wet coating

Abstract

The present application relates to the production process and equipment of knitted fabric small wet coating waterproof and breathable fabric, and the specific steps include, S1, sizing; S2, base cloth rolling; S3, wet coating film; S4, film coagulation; S5, washing; S6, drying and curing: the wet coating fabric after washing is transported to the coating fabric drying station, the two side edges of the wet coating fabric are clamped by the needle plate on the needle plate chain conveying mechanism and are conveyed forward, the Teflon conveying belt and the needle plate chain conveying mechanism keep the linear speed consistent through the synchronous control system, so that the wet coating fabric is dried and cured in the state of no tension sag and no relative sliding, and the waterproof and breathable fabric is prepared; S7, cooling and winding.The present application has the following advantages: the present application realizes the stress-free curing of the wet coating fabric through drying synchronous control, significantly improves the tear strength, waterproof performance and moisture permeability of the finished fabric, ensures the uniformity of the microporous structure, and prolongs the service life.

Description

Technical Field

[0001] This invention relates to the fields of functional textile new materials and intelligent processing technology, specifically to the production process and equipment for knitted fabrics with small wet-coating waterproof and breathable fabrics. Background Technology

[0002] Waterproof and breathable fabrics are special textiles that combine waterproofing and moisture permeability. Their core technology lies in forming a microporous polyurethane membrane on the surface of a base fabric such as nylon using a wet coating process. This membrane utilizes the selective permeability of liquid water and water vapor molecules through its micropores, allowing rainwater to penetrate while allowing sweat to escape. It is widely used in high-value-added textile fields such as outdoor sportswear, fire protective clothing, and medical isolation gowns.

[0003] Knitted fabrics, composed of loop structures, possess excellent extensibility and softness, but are prone to deformation and difficult to control uniformity during coating processing. Small-scale wet coating uses a low-concentration polyurethane slurry (resin content 20-30%) to form a thinner microporous membrane, maintaining the original soft hand feel and lightweight characteristics of the knitted fabric while ensuring waterproof and breathable performance. The processing challenges arising from combining knitted fabric with small-scale wet coating lie in the fact that the knitted base fabric is easily deformed by tension, and the thin coating layer is even more sensitive to tension control and temperature uniformity during the drying process; any longitudinal stretching may lead to film damage or destruction of the microporous structure.

[0004] The process of preparing waterproof and breathable fabrics includes steps such as sizing preparation, base fabric pretreatment, wet coating, film coagulation, washing, and drying / curing. Among these, drying / curing is the key step determining the final product's performance. After film coagulation and washing, the wet-coated fabric's polyurethane film layer is not fully cured, containing a large amount of moisture and residual dimethylformamide solvent. A drying process is necessary to thoroughly remove the solvent and stabilize the microporous structure. Current drying processes generally use a chain conveyor system with needle plates to traction and transport the wet-coated fabric. This traditional conveying method has revealed significant technical defects in actual production, directly affecting the overall performance of the finished fabric, specifically in the following aspects:

[0005] First, when a needle plate clamps the fabric edge and applies longitudinal tension for traction, the excessive stretching at the fabric edge causes the coating to thin, potentially damaging the microporous structure and creating tiny defects that are difficult to detect with the naked eye. These areas become channels for moisture penetration during actual use, leading to a decrease in the fabric's water pressure resistance. Meanwhile, in the middle of the fabric, shrinkage causes the coating to accumulate, increasing the micropore density. While this improves waterproofing, it correspondingly hinders breathability, resulting in reduced wearing comfort. Secondly, existing chain conveyor mechanisms, due to the polygonal effect of chain drive, exhibit periodic fluctuations in chain linear speed even with a constant input rotation speed. This speed fluctuation is transmitted to the traction of the wet coated fabric, subjecting it to alternating tension during drying, interfering with the uniform formation of the polyurethane membrane's microporous structure, thus affecting the fabric's waterproof and breathable properties.

[0006] Second, in the initial drying stage, the wet-coated fabric is still soft and easily deformable, and the polyurethane film has not yet fully cured. At this time, using needle plates to clamp the fabric edge and apply longitudinal tension restricts the fabric's natural shrinkage under heat, causing internal stress to freeze during the film curing process. This internal stress results in stress concentration at the interface between the polyurethane coating and the base fabric. When the finished fabric is subjected to tearing force, these stress concentration points become the starting point for crack initiation and propagation. More seriously, the "necking" phenomenon caused by needle plate traction leads to uneven coating thickness distribution between the fabric edge and the center. The coating thins due to excessive stretching at the edge, becoming a weak area for tear strength. When the fabric is used in outdoor clothing, this defect directly causes the garment to tear easily from weak points when subjected to abrasion or stretching, severely affecting the product's durability and lifespan.

[0007] Third, the wet-coated fabric is suspended under the traction of the needle plate and cannot adhere tightly to the surface of the conveyor belt. During the drying process, the hot air blowing can easily cause the fabric surface to shake or wrinkle, resulting in fine cracks, orange peel texture, or irregular patterns on the coating surface. These surface defects not only affect the appearance of the fabric but also become stress concentration points, accelerating coating aging or damage during subsequent lamination or use. Summary of the Invention

[0008] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a production process and equipment for a small wet-coating waterproof and breathable knitted fabric, effectively solving the above technical problems.

[0009] The objective of this invention is achieved through the following technical solution: a production process for a knitted fabric with a small wet-coating method to create a waterproof and breathable material, comprising the following specific steps:

[0010] S1. Slurry preparation: Select 70-80 parts by weight of dimethylformamide solvent and 20-30 parts by weight of polyurethane resin, mix and stir to prepare coating slurry;

[0011] S2. Base fabric rolling: The base fabric is introduced from the upper fabric station into the water tank containing waterproofing agent working liquid at the rolling mill station for immersion, and then rolled by the rolling mill.

[0012] S3, Wet coating: The coating slurry prepared in step S2 is uniformly coated onto the surface of the base fabric after rolling in step S2 through the coating head of the wet coating station.

[0013] S4. Membrane Coagulation: The base fabric coated with the coating slurry enters the membrane coagulation water tank at the membrane coagulation station. The membrane coagulation water tank contains a mixed solution of water and dimethylformamide solvent. The concentration of dimethylformamide solvent is controlled at 15-20%. Through bidirectional diffusion and replacement between water and dimethylformamide solvent, the polyurethane resin in the coating slurry coagulates and precipitates out, forming a wet coated fabric with a microporous structure.

[0014] S5. Water washing: The wet coated cloth after membrane coagulation passes through multiple water washing stations in sequence to remove residual dimethylformamide solvent.

[0015] S6. Drying and curing: The wet coated fabric after washing is conveyed to the coating fabric drying station. The two sides of the wet coated fabric are clamped by the needle plates on the needle plate chain conveyor mechanism and conveyed forward. At the same time, the lower surface of the wet coated fabric is laid flat on the surface of the Teflon conveyor belt. The Teflon conveyor belt and the needle plate chain conveyor mechanism maintain the same linear speed through the synchronous control system, so that the wet coated fabric is dried and cured in a state of no tension and no relative slippage, and a waterproof and breathable fabric is obtained.

[0016] S7. Cooling and winding: The dried waterproof and breathable fabric is cooled and inspected before being wound up at the winding station.

[0017] A further improvement of the present invention is that, in step S6, the synchronous control system includes a main input shaft that provides basic power to the needle plate chain conveying mechanism and the Teflon conveyor belt. The needle plate chain conveying mechanism is connected to the main input shaft via a first output gearbox, and the Teflon conveyor belt is connected to the main input shaft via a second output gearbox and a series electromagnetic speed-regulating clutch.

[0018] A further improvement of the present invention is that: in step S6, the synchronization control system achieves the same linear velocity between the two through the following basic synchronization control steps, wherein the basic synchronization control steps include,

[0019] S61. Real-time monitoring of the actual operating speed of the needle plate chain conveyor mechanism and the actual operating speed of the Teflon conveyor belt;

[0020] S62. Calculate the instantaneous speed deviation between the Teflon conveyor belt and the needle plate chain conveyor mechanism, and calculate the cumulative displacement deviation within the preset time window;

[0021] S63. The system presets speed deviation threshold and displacement deviation threshold. When the instantaneous speed deviation exceeds the system preset speed deviation threshold or the cumulative displacement deviation exceeds the system preset displacement deviation threshold, it is determined that the needle plate chain conveyor mechanism and the Teflon conveyor belt have lost synchronization.

[0022] S64. Output an adjustment signal to the electromagnetic speed regulating clutch, and adjust its output speed by changing the excitation current of the electromagnetic speed regulating clutch, so that the running speed of the Teflon conveyor belt approaches the actual running speed of the needle plate chain conveyor mechanism, until the instantaneous speed deviation falls back to within the system's preset speed deviation threshold, and the cumulative displacement deviation falls back to within the system's preset displacement deviation threshold.

[0023] A further improvement of the present invention is that the synchronization control system in step S6 also introduces a feedforward compensation control step for speed fluctuations in the needle plate chain conveyor mechanism. This control step is superimposed on the basic synchronization control step and specifically includes:

[0024] S65. Pre-obtain the number of teeth and operating speed of the drive sprocket of the needle plate chain conveyor, and determine the inherent periodic speed fluctuation characteristics of the needle plate chain conveyor based on the polygonal effect of chain transmission.

[0025] S66. Based on the frequency and amplitude characteristics of the periodic speed fluctuation, a feedforward compensation signal is generated. The waveform of the feedforward compensation signal is opposite to the speed fluctuation waveform of the needle plate chain conveyor mechanism, and is used to offset the influence of periodic speed fluctuation on synchronous operation.

[0026] S67. The feedforward compensation signal is superimposed on the excitation current adjustment signal of the electromagnetic speed regulating clutch, so that the running speed of the Teflon conveyor belt is based on the basic synchronous control, and an additional compensation component with the opposite phase and matching amplitude to the speed fluctuation of the needle plate chain conveyor mechanism is introduced.

[0027] A further improvement of the present invention is that the synchronization control system in step S6 also introduces a thermal expansion compensation control step for temperature changes. This step is performed in addition to the basic synchronization control step, and specifically includes:

[0028] S68. Multiple temperature sensors are installed along the conveying direction in the drying section to collect temperature data at each detection point in real time and obtain temperature field distribution information of the drying section.

[0029] S69. Based on the material thermal expansion characteristics of the Teflon conveyor belt and the temperature field distribution information, calculate the thermal elongation of the Teflon conveyor belt due to temperature changes.

[0030] S610. Calculate the speed compensation coefficient based on the thermal expansion. The speed compensation coefficient is used to correct the reference running speed of the Teflon conveyor belt to eliminate the speed drift between the Teflon conveyor belt and the needle plate chain conveyor mechanism caused by thermal expansion.

[0031] S611. The speed compensation coefficient is applied to the excitation current adjustment signal of the electromagnetic speed regulating clutch so that the running speed of the Teflon conveyor belt is dynamically corrected according to temperature changes.

[0032] A further improvement of the present invention is that, in step S6, the synchronous control system simultaneously introduces a feedforward compensation control step and a thermal expansion compensation control step, and adopts a composite control method, specifically including:

[0033] S612. Execute the feedforward compensation control step and the thermal expansion compensation control step respectively to obtain the feedforward compensation component and the thermal expansion compensation coefficient.

[0034] S613. The feedforward compensation component and the thermal expansion compensation coefficient are fused together to generate a composite excitation current adjustment command.

[0035] S614. The composite excitation current adjustment command is output to the electromagnetic speed regulating clutch, so that the running speed of the Teflon conveyor belt can be dynamically corrected for the thermal deformation caused by chain drive speed fluctuations and temperature changes, so as to achieve precise synchronization under all working conditions.

[0036] A production equipment for waterproof and breathable fabric based on synchronous control includes a fabric loading station, a rolling station, a base fabric drying station, a wet coating station, a film coagulation station, a washing station, a coated fabric drying station, and a winding station arranged sequentially along the base fabric travel direction, and also includes a needle plate chain conveying mechanism that runs through each station in sequence.

[0037] The coated fabric drying station has multiple drying sections, and the needle plate chain conveyor mechanism runs horizontally through the multiple drying sections. The coated fabric drying station also includes a closed ring-shaped Teflon conveyor belt placed on the lower end face of the needle plate chain conveyor mechanism, as well as a synchronization control system that controls the needle plate chain conveyor mechanism and the Teflon conveyor belt to move synchronously.

[0038] The needle plate chain conveyor mechanism includes two parallel conveyor chains and needle plates evenly distributed on each conveyor chain. The needle plates clamp the side edges of the base fabric or wet coated fabric. The conveyor chains are wound around sprockets mounted on the drive shaft. Support and transmission are achieved through the meshing of the sprockets and the conveyor chains. The Teflon conveyor belt is wound between the main drive roller and the driven roller to achieve support and transmission.

[0039] A further improvement of the present invention is that the synchronous control system includes a main input shaft, a main motor, a first output gearbox, a second output gearbox, an electromagnetic speed-regulating clutch, a speed detection unit, a temperature sensor unit, and a controller. The controller is electrically connected to the speed detection unit, the temperature sensor unit, the electromagnetic speed-regulating clutch, and the main motor. The main motor is driven by the main input shaft. The input end of the first output gearbox is driven by the main input shaft, and its output end is driven by the drive shaft of the needle plate chain conveyor mechanism. The input end of the second output gearbox is driven by the main input shaft, and its output end is driven by the main drive roller of the Teflon conveyor belt through the electromagnetic speed-regulating clutch. The system also includes a third gearbox located at the base fabric drying station and a fourth gearbox located at the winding station. The input ends of both the third and fourth gearboxes are driven by the main input shaft, and their output ends are respectively connected to the drive shafts fitted at the corresponding stations.

[0040] A further improvement of the present invention is that the speed detection unit includes:

[0041] The first encoder is mounted on the drive shaft and is used to detect the actual operating speed of the needle plate chain conveyor mechanism in real time and output a first speed signal.

[0042] The second encoder is installed on the main drive roller of the Teflon conveyor belt and is used to detect the actual running speed of the Teflon conveyor belt in real time and output a second speed signal.

[0043] The controller is electrically connected to the first encoder and the second encoder respectively, and receives the first speed signal and the second speed signal.

[0044] A further improvement of the present invention is that: the electromagnetic speed regulating clutch is disposed between the output shaft of the second output gearbox and the input shaft of the main drive roller of the Teflon conveyor belt;

[0045] The input rotor of the electromagnetic speed-regulating clutch is driven by the output shaft of the second output gearbox, and the output rotor of the electromagnetic speed-regulating clutch is driven by the main drive roller of the Teflon conveyor belt. The controller controls the slip between the input rotor and the output rotor by adjusting the excitation current of the electromagnetic speed-regulating clutch, thereby achieving stepless fine adjustment of the running speed of the Teflon conveyor belt.

[0046] Compared with the prior art, the present invention has the following advantages:

[0047] 1. This invention achieves tension-free conveying of wet coated fabric during the drying process through synchronous control of the Teflon conveyor belt and the needle plate chain conveyor mechanism. The two edges of the wet coated fabric are held forward by needle plates on the needle plate chain conveyor mechanism, while the lower surface lies flat on the Teflon conveyor belt. The synchronous control system ensures precise consistency in the linear speeds of both, allowing the fabric to dry and cure in a tension-free, non-slip state. This avoids longitudinal stretching of the fabric during drying, allowing the polyurethane film to shrink and cure freely, resulting in a stress-free interface between the coating and the base fabric. When the finished fabric is subjected to tearing force, the coating and base fabric work together to distribute stress evenly rather than concentrating it in weak areas, thus significantly improving tear strength.

[0048] 2. This invention uses a synchronous control system to precisely compensate for the inherent speed fluctuations and thermal expansion caused by temperature changes in the chain conveyor mechanism, providing a stable conveying environment for the wet-coated fabric and ensuring the uniform formation of the microporous structure of the polyurethane membrane. Feedforward compensation control generates a compensation signal with the opposite phase to the speed fluctuation based on the polygonal effect of the chain drive. Thermal expansion compensation dynamically corrects the conveyor belt speed based on the temperature field distribution. The synchronous control method ensures that the wet-coated fabric remains in a stable conveying state throughout the drying process. The polyurethane membrane completes phase transformation and micropore shaping under undisturbed conditions, forming a microporous membrane with uniform pore size distribution and regular structure, thereby improving the waterproof and breathable performance of the final fabric.

[0049] 3. The synchronous control system in this application ensures that the overall transmission is of the same origin through the main motor, achieves fine adjustment through the electromagnetic clutch, and integrates multiple sensors to compensate for disturbances. This not only solves the problem that it is difficult to achieve absolute synchronization in multi-motor drive, but also breaks through the limitation that single-motor drive cannot be adjusted independently. Ultimately, it achieves high-precision synchronous operation of Teflon conveyor belt and needle plate chain conveyor mechanism under all working conditions. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the structure of the production equipment for the small wet-coating waterproof and breathable knitted fabric of the present invention.

[0051] Figure 2 This is a top view of the production equipment for the knitted fabric wet-coated waterproof and breathable fabric of the present invention.

[0052] Figure 3 for Figure 1 A partial structural diagram of the needle plate chain conveyor mechanism.

[0053] Numbering on the map:

[0054] 1-Fabric loading station, 2-Rolling station, 3-Base fabric drying station, 4-Wet coating station, 5-Film coagulation station, 6-Washing station, 7-Coated fabric drying station, 8-Rolling station, 9-Needle plate chain conveyor mechanism, 10-Teflon conveyor belt, 11-Base fabric, 12-Wet coated fabric, 13-Main drive roller, 14-Driven roller, 15-Main input shaft, 16-Main motor, 17-First output gearbox, 18-Second output gearbox, 19-Electromagnetic speed regulating clutch, 20-Third output gearbox, 21-Fourth output gearbox, 22-Drive shaft, 23-First encoder, 24-Second encoder, 25-Temperature sensor;

[0055] 91-Conveyor chain, 92-Needle plate, 93-Drive shaft, 94-Sprocket. Detailed Implementation

[0056] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments and accompanying drawings. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0057] In the description of this invention, it should be understood that the terms indicating orientation or positional relationship, such as those based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the structure or unit referred to must have a specific orientation, and therefore should not be construed as a limitation of this invention.

[0058] In this invention, unless otherwise explicitly specified and limited, terms such as “connection,” “provided with,” and “have” should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. They can be described as a mechanical connection, a direct connection, or a connection through an intermediate medium. Those skilled in the art can understand the basic meaning of the above terms in this invention according to the specific circumstances.

[0059] The production process of knitted fabric with wet-coating for waterproof and breathable properties is referenced. Figure 1 S1. Slurry preparation: Select 70-80 parts by weight of dimethylformamide solvent and 20-30 parts by weight of polyurethane resin, mix and stir to prepare coating slurry;

[0060] S2. Base fabric rolling: The base fabric is introduced from the upper fabric station into the water tank containing waterproofing agent working liquid at the rolling mill station for immersion, and then rolled by the rolling mill.

[0061] S3, Wet coating: The coating slurry prepared in step S2 is uniformly coated onto the surface of the base fabric after rolling in step S2 through the coating head of the wet coating station.

[0062] S4. Membrane Coagulation: The base fabric coated with the coating slurry enters the membrane coagulation water tank at the membrane coagulation station. The membrane coagulation water tank contains a mixed solution of water and dimethylformamide solvent. The concentration of dimethylformamide solvent is controlled at 15-20%. Through bidirectional diffusion and replacement between water and dimethylformamide solvent, the polyurethane resin in the coating slurry coagulates and precipitates out, forming a wet coated fabric with a microporous structure.

[0063] S5. Water washing: The wet coated cloth after membrane coagulation passes through multiple water washing stations in sequence to remove residual dimethylformamide solvent.

[0064] S6. Drying and curing: The wet coated fabric after washing is conveyed to the coating fabric drying station. The two sides of the wet coated fabric are clamped by the needle plates on the needle plate chain conveyor mechanism and conveyed forward. At the same time, the lower surface of the wet coated fabric is laid flat on the surface of the Teflon conveyor belt. The Teflon conveyor belt and the needle plate chain conveyor mechanism maintain the same linear speed through the synchronous control system, so that the wet coated fabric is dried and cured in a state of no tension and no relative slippage, and a waterproof and breathable fabric is obtained.

[0065] S7. Cooling and winding: The dried waterproof and breathable fabric is cooled and inspected before being wound up at the winding station.

[0066] This invention achieves tension-free conveying of the wet coated fabric during the drying process through synchronous control of the Teflon conveyor belt 10 and the needle plate chain conveyor mechanism 9. The two edges of the wet coated fabric 12 are clamped and conveyed forward by the needle plates 92 on the needle plate chain conveyor mechanism 9, while its lower surface lies flat on the surface of the Teflon conveyor belt 10. The synchronous control system ensures that the linear speeds of both are precisely consistent, allowing the fabric to complete drying and curing in a tension-free, drooping state without relative slippage. This avoids longitudinal stretching of the fabric during drying, allowing the polyurethane film to shrink and cure freely, and ensuring a stress-free interface between the coating and the base fabric. When the finished fabric is subjected to tearing force, the coating and the base fabric work together to distribute the stress evenly rather than concentrating it in weak areas, thus significantly improving tear strength.

[0067] The Teflon conveyor belt 10 in this invention not only serves as a support carrier, working in conjunction with the needle plate chain conveyor mechanism 9 to achieve tension-free conveying, but its unique anti-stick properties, high-temperature resistance, and low coefficient of friction also play a crucial role in improving fabric quality. The extremely low surface energy of Teflon material effectively prevents wet coating adhesion, ensuring a smooth and intact fabric surface after drying. The low coefficient of friction allows the fabric to shrink freely on the support surface without being affected by resistance, avoiding localized stretching or wrinkling. The continuous and flat support surface eliminates the shaking phenomenon caused by fabric suspension, allowing the coating to cure and solidify under undisturbed conditions, resulting in a smooth and flat surface free of defects such as micro-cracks and orange peel texture, significantly improving the product's appearance quality and service life.

[0068] Furthermore, in step S6, the synchronous control system includes a main input shaft 15 that provides basic power to the needle plate chain conveyor mechanism 9 and the Teflon conveyor belt 10. The needle plate chain conveyor mechanism 9 is connected to the main input shaft 15 through a first output gearbox 17, and the Teflon conveyor belt 10 is connected to the main input shaft 15 through a second output gearbox 18 and a series electromagnetic speed regulating clutch 19.

[0069] Based on this embodiment, in step S6, the synchronization control system achieves the same linear velocity between the two through the following basic synchronization control steps, which include:

[0070] S61. Real-time monitoring of the actual operating speed of the needle plate chain conveyor mechanism 9 and the actual operating speed of the Teflon conveyor belt 10;

[0071] S62. Calculate the instantaneous speed deviation between the Teflon conveyor belt 10 and the needle plate chain conveyor mechanism 9, and calculate the cumulative displacement deviation within the preset time window.

[0072] S63. The system presets speed deviation threshold and displacement deviation threshold. When the instantaneous speed deviation exceeds the system preset speed deviation threshold or the cumulative displacement deviation exceeds the system preset displacement deviation threshold, it is determined that the needle plate chain conveyor mechanism 9 and the Teflon conveyor belt 10 have lost synchronization.

[0073] S64. Output an adjustment signal to the electromagnetic speed regulating clutch 19, and adjust its output speed by changing the excitation current of the electromagnetic speed regulating clutch 19, so that the running speed of the Teflon conveyor belt 10 approaches the actual running speed of the needle plate chain conveyor mechanism 9, until the instantaneous speed deviation falls back to within the system's preset speed deviation threshold, and the cumulative displacement deviation falls back to within the system's preset displacement deviation threshold.

[0074] Based on this embodiment, the synchronization control system in step S6 further introduces a feedforward compensation control step for speed fluctuations in the needle plate chain conveyor mechanism 9. This control step is superimposed on the basic synchronization control step and specifically includes:

[0075] S65. The number of teeth and operating speed of the drive sprocket 94 of the needle plate chain conveyor mechanism 9 are obtained in advance, and the inherent periodic speed fluctuation characteristics of the needle plate chain conveyor mechanism 9 are determined according to the polygonal effect of chain transmission.

[0076] S66. Based on the frequency and amplitude characteristics of the periodic speed fluctuation, a feedforward compensation signal is generated. The waveform of the feedforward compensation signal is opposite to the speed fluctuation waveform of the needle plate chain conveyor mechanism 9, and is used to offset the influence of the periodic speed fluctuation on synchronous operation.

[0077] S67. The feedforward compensation signal is superimposed on the excitation current adjustment signal of the electromagnetic speed regulating clutch 19, so that the running speed of the Teflon conveyor belt 10 is based on the basic synchronous control, and an additional compensation component with the opposite phase and matching amplitude to the speed fluctuation of the needle plate chain conveyor mechanism 9 is introduced.

[0078] Based on this embodiment, the synchronization control system in step S6 further introduces a thermal expansion compensation control step for temperature changes. This step is executed in addition to the basic synchronization control steps, and specifically includes:

[0079] S68. Multiple temperature sensors 25 are installed along the conveying direction in the drying section to collect temperature data at each detection point in real time and obtain temperature field distribution information of the drying section.

[0080] S69. Based on the material thermal expansion characteristics of the Teflon conveyor belt 10 and the temperature field distribution information, calculate the thermal elongation of the Teflon conveyor belt 10 due to temperature changes.

[0081] S610. Calculate the speed compensation coefficient based on the thermal expansion. This speed compensation coefficient is used to correct the reference running speed of the Teflon conveyor belt 10 to eliminate the speed drift between the Teflon conveyor belt 10 and the needle plate chain conveyor mechanism 9 caused by thermal expansion.

[0082] S611. Apply the speed compensation coefficient to the excitation current adjustment signal of the electromagnetic speed regulating clutch 19 so that the running speed of the Teflon conveyor belt 10 is dynamically corrected according to temperature changes.

[0083] Based on the above embodiments, in step S6, the synchronous control system simultaneously introduces a feedforward compensation control step and a thermal expansion compensation control step, and adopts a composite control method, specifically including:

[0084] S612. Execute the feedforward compensation control step and the thermal expansion compensation control step respectively to obtain the feedforward compensation component and the thermal expansion compensation coefficient.

[0085] S613. The feedforward compensation component and the thermal expansion compensation coefficient are fused together to generate a composite excitation current regulation command.

[0086] S614. The composite excitation current adjustment command is output to the electromagnetic speed regulating clutch 19, so that the running speed of the Teflon conveyor belt 10 can be dynamically corrected for the thermal deformation caused by chain drive speed fluctuation and temperature change, so as to achieve precise synchronization under all working conditions.

[0087] This invention provides a stable conveying environment for the wet-state coated fabric by precisely compensating for the inherent speed fluctuations and thermal expansion caused by temperature changes in the needle plate chain conveyor mechanism 9 through a synchronous control system, ensuring the uniform formation of the microporous structure of the polyurethane film. Feedforward compensation control generates a compensation signal with the opposite phase to the speed fluctuation based on the polygonal effect of the chain drive, while thermal expansion compensation dynamically corrects the conveyor belt speed based on the temperature field distribution. This synchronous control method ensures that the wet-state coated fabric remains in a stable conveying state throughout the drying process, allowing the polyurethane film to complete phase transformation and micropore shaping under undisturbed conditions, forming a microporous membrane with uniform pore size distribution and regular structure, thereby improving the waterproof and breathable performance of the final fabric.

[0088] Production equipment for small-scale wet-coating waterproof and breathable knitted fabrics, refer to... Figure 2 It includes a fabric loading station 1, a rolling station 2, a base fabric drying station 3, a wet coating station 4, a film solidification station 5, a water washing station 6, a coated fabric drying station 7, and a winding station 8 arranged sequentially along the base fabric 11. It also includes a needle plate chain conveying mechanism 9 that runs through each station in sequence.

[0089] The coated fabric drying station 7 has multiple drying sections inside, and the needle plate chain conveyor mechanism 9 horizontally runs through multiple drying sections. The coated fabric drying station 7 also includes an annular closed Teflon conveyor belt 10 placed on the lower end face of the needle plate chain conveyor mechanism 9, and a synchronous control system that controls the needle plate chain conveyor mechanism 9 and the Teflon conveyor belt 10 to move synchronously.

[0090] Reference Figure 3 The needle plate chain conveying mechanism 9 includes two parallel conveying chains 91 and needle plates 92 evenly distributed on each conveying chain 91. The needle plates 92 clamp the side edge of the base fabric 11 or the wet coated fabric 12. The conveying chains 91 are wound around the sprockets 94 mounted on the drive shaft 93. The sprockets 94 and the conveying chains 91 are engaged to achieve support and transmission. The Teflon conveyor belt 10 is wound between the main drive roller 13 and the driven roller 14 to achieve support and transmission.

[0091] Based on the above embodiments, the synchronous control system includes a main input shaft 15, a main motor 16, a first output gearbox 17, a second output gearbox 18, an electromagnetic speed-regulating clutch 19, a speed detection unit, a temperature sensor unit, and a controller. The controller is electrically connected to the speed detection unit, the temperature sensor unit, the electromagnetic speed-regulating clutch 19, and the main motor. The main motor is driven by the main input shaft 15. The input end of the first output gearbox 17 is driven by the main input shaft 15, and its output end is driven by the drive shaft 93 of the needle plate chain conveyor mechanism 9. The input end of the second output gearbox 18 is driven by the main input shaft 15, and its output end is driven by the main drive roller 13 of the Teflon conveyor belt 10 through the electromagnetic speed-regulating clutch 19. The system also includes a third gearbox 20 placed at the base fabric drying station 3 and a fourth gearbox 21 placed at the winding station 8. The input ends of the third gearbox 20 and the fourth gearbox 21 are both driven by the main input shaft 15, and their output ends are respectively connected to the drive shaft 22 sleeved at the corresponding station.

[0092] In this invention, the synchronous control system uses a main motor to simultaneously drive the needle plate chain conveyor mechanism 9 and the Teflon conveyor belt 10 through the main input shaft. The power source for both is the same mechanical source. This homogeneous transmission structure ensures that the speed ratio between the two under ideal conditions is determined by the fixed gearbox speed ratio. This fundamentally avoids the inherent speed deviation caused by differences in motor response characteristics, load fluctuations, or control command delays in multi-motor drive systems. Even without any electronic adjustment, the two maintain mechanical-level coarse synchronization, providing a stable reference platform for subsequent precise control.

[0093] Secondly, the synchronous control system achieves independent fine-tuning based on the same source by connecting an electromagnetic speed-regulating clutch 19 in series between the second output gearbox 18 and the main drive roller 13 of the Teflon conveyor belt 10. The electromagnetic speed-regulating clutch 19 controls the slip between the input and output rotors by changing the excitation current, enabling stepless, real-time, and high-precision speed correction of the Teflon conveyor belt 10 without changing the speed of the main motor or interrupting the continuous operation of the production line. This design retains the mechanical coupling between the two while giving the Teflon conveyor belt the ability to independently fine-tune, achieving a high degree of unity between synchronization and regulation.

[0094] Furthermore, the speed detection unit includes

[0095] The first encoder 23 is mounted on the drive shaft 93 and is used to detect the actual running speed of the needle plate chain conveyor mechanism 9 in real time and output a first speed signal.

[0096] The second encoder 24 is installed on the main drive roller 13 of the Teflon conveyor belt 10 and is used to detect the actual running speed of the Teflon conveyor belt 10 in real time and output a second speed signal.

[0097] The controller is electrically connected to the first encoder 23 and the second encoder 24 respectively, and receives the first speed signal and the second speed signal.

[0098] Furthermore, the electromagnetic speed-regulating clutch 19 is disposed between the output shaft of the second output gearbox 18 and the input shaft of the main drive roller 13 of the Teflon conveyor belt 10;

[0099] The input rotor of the electromagnetic speed-regulating clutch 19 is connected to the output shaft of the second output gearbox 18, and the output rotor of the electromagnetic speed-regulating clutch 19 is connected to the main drive roller 13 of the Teflon conveyor belt 10. The controller controls the slip between the input rotor and the output rotor by adjusting the excitation current of the electromagnetic speed-regulating clutch 19, thereby realizing stepless fine adjustment of the running speed of the Teflon conveyor belt 10.

[0100] Table 1 compares the performance of fabrics produced by the present invention with those produced by traditional processes.

[0101] Performance indicators Traditional technique (needle plate traction only) This invention (tension-free synchronous control) <![CDATA[Water pressure resistance (mmH2O)]]> ≥8000 ≥12000 Moisture permeability (g / m²·24h) ≥8000 ≥11000 Tear strength (N) 15 (seam) / 22 (center) 28 (uniform distribution) Fabric smoothness (grade) Level 3-4 (with slight wrinkles) Level 5 (No wrinkles)

[0102] This invention achieves tension-free conveying of wet-coated fabric during the drying process through synchronous control technology, significantly improving the overall performance of waterproof and breathable fabrics. As shown in Table 1, compared with traditional needle-plate traction technology, this invention achieves breakthrough improvements in several key indicators.

[0103] The water pressure resistance has increased from ≥8000mmH2O to ≥12000mmH2O. This is attributed to the synchronous control system's precise compensation for the periodic speed fluctuations of the chain drive and the speed drift caused by thermal expansion. This allows the polyurethane membrane to complete phase transformation and micropore shaping under undisturbed conditions, forming a microporous membrane with uniform pore size distribution and regular structure, effectively blocking the penetration of liquid water. The moisture permeability has increased from ≥8000g / m²·24h to ≥11000g / m²·24h, indicating that the uniformity of the microporous structure not only enhances the waterproof performance but also optimizes the permeation channels for water vapor molecules, achieving a dual improvement in both waterproofing and moisture permeability.

[0104] The tear strength is improved from an uneven distribution of 15N at the fabric edge and 22N in the fabric to a uniform distribution of 28N. This is the most significant technical breakthrough of this invention. In traditional processes, needle plate traction causes excessive stretching of the fabric edge and thinning of the coating, which becomes a weak area for tear strength. However, this invention, through the synchronous operation of the Teflon conveyor belt and the needle plate chain, allows the fabric to be dried and cured in a tension-free drooping state. The polyurethane film layer can shrink freely, and there is no stress concentration at the interface between the coating and the base fabric. The stress distribution is uniform, and the weak area at the fabric edge is completely eliminated.

[0105] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A production process for a knitted fabric with a small wet-coating method to create a waterproof and breathable material, characterized by: The specific steps include S1. Slurry preparation: Select 70-80 parts by weight of dimethylformamide solvent and 20-30 parts by weight of polyurethane resin, mix and stir to prepare coating slurry; S2. Base fabric rolling: The base fabric is introduced from the upper fabric station into the water tank containing waterproofing agent working liquid at the rolling mill station for immersion, and then rolled by the rolling mill. S3, Wet coating: The coating slurry prepared in step S2 is uniformly coated onto the surface of the base fabric after rolling in step S2 through the coating head of the wet coating station. S4. Membrane Coagulation: The base fabric coated with the coating slurry enters the membrane coagulation water tank at the membrane coagulation station. The membrane coagulation water tank contains a mixed solution of water and dimethylformamide solvent. The concentration of dimethylformamide solvent is controlled at 15-20%. Through bidirectional diffusion and replacement between water and dimethylformamide solvent, the polyurethane resin in the coating slurry coagulates and precipitates out, forming a wet coated fabric with a microporous structure. S5. Water washing: The wet coated cloth after membrane coagulation passes through multiple water washing stations in sequence to remove residual dimethylformamide solvent. S6. Drying and curing: The wet coated fabric after washing is conveyed to the coating fabric drying station. The two sides of the wet coated fabric are clamped by the needle plates on the needle plate chain conveyor mechanism and conveyed forward. At the same time, the lower surface of the wet coated fabric is laid flat on the surface of the Teflon conveyor belt. The Teflon conveyor belt and the needle plate chain conveyor mechanism maintain the same linear speed through the synchronous control system, so that the wet coated fabric is dried and cured in a state of no tension and no relative slippage, and a waterproof and breathable fabric is obtained. S7. Cooling and winding: The dried waterproof and breathable fabric is cooled and inspected before being wound up at the winding station.

2. The production process of the knitted fabric with wet-coating waterproof and breathable properties according to claim 1, characterized in that: In step S6, the synchronous control system includes a main input shaft that provides basic power to the needle plate chain conveyor mechanism and the Teflon conveyor belt. The needle plate chain conveyor mechanism is connected to the main input shaft via a first output gearbox, and the Teflon conveyor belt is connected to the main input shaft via a second output gearbox and a series electromagnetic speed-regulating clutch.

3. The production process of the knitted fabric with wet-coating waterproof and breathable properties according to claim 2, characterized in that: In step S6, the synchronization control system achieves the same linear velocity between the two devices through the following basic synchronization control steps, which include: S61. Real-time monitoring of the actual operating speed of the needle plate chain conveyor mechanism and the actual operating speed of the Teflon conveyor belt; S62. Calculate the instantaneous speed deviation between the Teflon conveyor belt and the needle plate chain conveyor mechanism, and calculate the cumulative displacement deviation within the preset time window; S63. The system presets speed deviation threshold and displacement deviation threshold. When the instantaneous speed deviation exceeds the system preset speed deviation threshold or the cumulative displacement deviation exceeds the system preset displacement deviation threshold, it is determined that the needle plate chain conveyor mechanism and the Teflon conveyor belt have lost synchronization. S64. Output an adjustment signal to the electromagnetic speed regulating clutch, and adjust its output speed by changing the excitation current of the electromagnetic speed regulating clutch, so that the running speed of the Teflon conveyor belt approaches the actual running speed of the needle plate chain conveyor mechanism, until the instantaneous speed deviation falls back to within the system's preset speed deviation threshold, and the cumulative displacement deviation falls back to within the system's preset displacement deviation threshold.

4. The production process of the knitted fabric with wet-coating waterproof and breathable properties according to claim 3, characterized in that: The synchronization control system in step S6 also introduces a feedforward compensation control step for speed fluctuations in the needle plate chain conveyor mechanism. This control step is executed in addition to the basic synchronization control steps, and specifically includes... S65. Pre-obtain the number of teeth and operating speed of the drive sprocket of the needle plate chain conveyor, and determine the inherent periodic speed fluctuation characteristics of the needle plate chain conveyor based on the polygonal effect of chain transmission. S66. Based on the frequency and amplitude characteristics of the periodic speed fluctuation, a feedforward compensation signal is generated. The waveform of the feedforward compensation signal is opposite to the speed fluctuation waveform of the needle plate chain conveyor mechanism, and is used to offset the influence of periodic speed fluctuation on synchronous operation. S67. The feedforward compensation signal is superimposed on the excitation current adjustment signal of the electromagnetic speed regulating clutch, so that the running speed of the Teflon conveyor belt is based on the basic synchronous control, and an additional compensation component with the opposite phase and matching amplitude to the speed fluctuation of the needle plate chain conveyor mechanism is introduced.

5. The production process of the knitted fabric with wet-coating waterproof and breathable material according to claim 3 or 4, characterized in that: The synchronization control system in step S6 also introduces a thermal expansion compensation control step for temperature changes. This step is executed in addition to the basic synchronization control steps, and specifically includes: S68. Multiple temperature sensors are installed along the conveying direction in the drying section to collect temperature data at each detection point in real time and obtain temperature field distribution information of the drying section. S69. Based on the material thermal expansion characteristics of the Teflon conveyor belt and the temperature field distribution information, calculate the thermal elongation of the Teflon conveyor belt due to temperature changes. S610. Calculate the speed compensation coefficient based on the thermal expansion. The speed compensation coefficient is used to correct the reference running speed of the Teflon conveyor belt to eliminate the speed drift between the Teflon conveyor belt and the needle plate chain conveyor mechanism caused by thermal expansion. S611. The speed compensation coefficient is applied to the excitation current adjustment signal of the electromagnetic speed regulating clutch so that the running speed of the Teflon conveyor belt is dynamically corrected according to temperature changes.

6. The production process of the knitted fabric with wet-coating waterproof and breathable properties according to claim 5, characterized in that: In step S6, the synchronous control system simultaneously introduces a feedforward compensation control step and a thermal expansion compensation control step, and adopts a composite control method, specifically including: S612. Execute the feedforward compensation control step and the thermal expansion compensation control step respectively to obtain the feedforward compensation component and the thermal expansion compensation coefficient. S613. The feedforward compensation component and the thermal expansion compensation coefficient are fused together to generate a composite excitation current adjustment command. S614. The composite excitation current adjustment command is output to the electromagnetic speed regulating clutch, so that the running speed of the Teflon conveyor belt can be dynamically corrected for the thermal deformation caused by chain drive speed fluctuations and temperature changes, so as to achieve precise synchronization under all working conditions.

7. An apparatus for implementing the production process of the knitted wet-coated waterproof and breathable fabric as described in claim 6, characterized in that: It includes a fabric loading station, a rolling station, a base fabric drying station, a wet coating station, a film solidification station, a washing station, a coated fabric drying station, and a winding station arranged sequentially along the base fabric travel direction, as well as a needle plate chain conveyor mechanism that runs through each station in sequence. The coated fabric drying station has multiple drying sections inside, and the needle plate chain conveyor mechanism horizontally runs through the multiple drying sections. The coated fabric drying station also includes an annular closed Teflon conveyor belt placed on the lower end face of the needle plate chain conveyor mechanism, and a synchronization control system that controls the needle plate chain conveyor mechanism and the Teflon conveyor belt to move synchronously. The needle plate chain conveying mechanism includes two parallel conveying chains and needle plates evenly distributed on each conveying chain. The needle plates clamp the side edges of the base fabric or wet coated fabric. The conveying chains are wound around sprockets mounted on the drive shaft. Support and transmission are achieved through the meshing of the sprockets and the conveying chains. The Teflon conveyor belt is wound between the main drive roller and the driven roller to achieve support and transmission.

8. The production equipment for knitted wet-coated waterproof and breathable fabric according to claim 7, characterized in that: The synchronous control system includes a main input shaft, a main motor, a first output gearbox, a second output gearbox, an electromagnetic speed-regulating clutch, a speed detection unit, a temperature sensor unit, and a controller. The controller is electrically connected to the speed detection unit, the temperature sensor unit, the electromagnetic speed-regulating clutch, and the main motor. The main motor is driven by the main input shaft. The input end of the first output gearbox is driven by the main input shaft, and its output end is driven by the drive shaft of the needle plate chain conveyor mechanism. The input end of the second output gearbox is driven by the main input shaft, and its output end is driven by the main drive roller of the Teflon conveyor belt through the electromagnetic speed-regulating clutch. The system also includes a third gearbox located at the base fabric drying station and a fourth gearbox located at the winding station. The input ends of the third and fourth gearboxes are both driven by the main input shaft, and their output ends are respectively connected to the drive shafts fitted at the corresponding stations.

9. The production equipment for knitted wet-coated waterproof and breathable fabric according to claim 8, characterized in that: The speed detection unit includes The first encoder is mounted on the drive shaft and is used to detect the actual operating speed of the needle plate chain conveyor mechanism in real time and output a first speed signal. The second encoder is installed on the main drive roller of the Teflon conveyor belt and is used to detect the actual running speed of the Teflon conveyor belt in real time and output a second speed signal. The controller is electrically connected to the first encoder and the second encoder respectively, and receives the first speed signal and the second speed signal.

10. The production equipment for knitted wet-coated waterproof and breathable fabric according to claim 9, characterized in that: The electromagnetic speed-regulating clutch is located between the output shaft of the second output gearbox and the input shaft of the main drive roller of the Teflon conveyor belt. The input rotor of the electromagnetic speed-regulating clutch is driven to the output shaft of the second output gearbox, and the output rotor of the electromagnetic speed-regulating clutch is driven to the main drive roller of the Teflon conveyor belt. The controller controls the slip between the input rotor and the output rotor by adjusting the excitation current of the electromagnetic speed-regulating clutch, thereby realizing stepless fine adjustment of the running speed of the Teflon conveyor belt.

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