Template-based bio-based microporous membrane coating device and method

Abstract

The invention relates to a film coating device and method for a bio-based microporous film based on a template. The device comprises a base material unwinding assembly, a tension control assembly, a hot pressing assembly, a slit sizing curtain, a suction assembly and an ultraviolet rolling assembly which are sequentially arranged in the material conveying direction. The hot pressing assembly is provided with a precise temperature control module and a pressure gradient adjusting module and is used for pre-fixing the modified nanofiber skeleton to form a template; the slit sizing curtain is used for infiltrating and filling the bio-based polyurethane resin into the template; the suction assembly is used for realizing gradient negative pressure permeation and directional filling of resin in template pores; the ultraviolet rolling assembly comprises an ultraviolet light source module and a pair of pressing rollers and is used for conducting ultraviolet crosslinking and rolling forming on the filled template. Compared with the prior art, the device has the advantages that efficient, deep and uniform filling of nanoscale pores is achieved, the technological process is shortened, the surface flatness and function consistency of the film are achieved, and the whole-process intelligent and high-precision control is achieved.

Description

Technical Field

[0001] This invention relates to the field of bio-based microporous membrane technology, and in particular to a template-based bio-based microporous membrane coating apparatus and method. Background Technology

[0002] Bio-based microporous membranes have attracted much attention due to their high porosity, biodegradability, and excellent mechanical properties. However, their industrial production still faces key technological bottlenecks, especially the poor uniformity and uncontrollable pore structure that exist when filling bio-based resins into nanofiber skeletons using traditional impregnation processes. These problems severely restrict the stability of material properties and the efficiency of large-scale production.

[0003] Traditional slot coating technology relies on the static leveling properties of the casting solution, making it difficult to overcome the uneven permeation resistance caused by the high viscosity (>5000 mPa·s) of bio-based resins. Especially within nanoscale pores (50-500 nm), the resin is prone to localized accumulation or sagging defects, resulting in a pore filling rate of less than 60% and poor longitudinal connectivity. Existing improvements, such as vacuum-assisted permeation, can improve filling efficiency, but a single negative pressure (typically 0.1-0.2 MPa) cannot accommodate the permeation kinetic differences across multiple pore sizes, leading to a dead zone rate of over 20% in micropores (<100 nm), severely impacting the membrane's moisture permeability and mechanical strength.

[0004] To address the above issues, the industry has proposed several improvement solutions: reducing resin viscosity through ultrasonic cavitation, but prolonged ultrasonic treatment can damage the nanofiber structure and consumes a lot of energy; using pre-made porous templates to guide resin filling, but the template preparation process is complex and has poor compatibility with the coating process; increasing filling depth through staged pressurization, but lacking a dynamic feedback mechanism, the matching accuracy between pressure parameters and pore size is insufficient. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art by providing a template-based bio-based microporous membrane coating device and method, which achieves efficient, deep, and uniform filling of nanoscale pores; shortens the process flow and improves the mechanical properties of the product; achieves membrane surface smoothness and functional consistency; and enables intelligent and high-precision control of the entire process.

[0006] The objective of this invention can be achieved through the following technical solutions: To overcome the shortcomings of the existing technology, this invention proposes a template-based bio-based microporous membrane coating device. By controlling the sizing device, gradient negative pressure permeation, and ultraviolet rolling, a highly efficient and precise bio-based microporous membrane coating system is constructed, providing a reliable solution for the large-scale production of high-performance environmentally friendly membrane materials.

[0007] The present invention provides a template-based bio-based microporous membrane coating device, comprising a substrate unwinding assembly, a tension control assembly, a hot pressing assembly, a slit coating curtain, a suction assembly, and an ultraviolet roller pressing assembly arranged sequentially along the material conveying direction; The hot-pressing assembly has a precision temperature control module and a pressure gradient adjustment module, which are used to pre-fix the modified nanofiber skeleton to form a template; The slit sealing curtain is used to permeate and fill the template with bio-based polyurethane resin. The suction assembly has a multi-stage negative pressure module and a porous vacuum adsorption platform, which are used to realize the gradient negative pressure penetration and directional filling of resin in the template pores; The ultraviolet roll forming assembly includes an ultraviolet light source module and a pair of pressure rollers, used for ultraviolet cross-linking and roll forming of the filled template.

[0008] The substrate unwinding assembly and hot pressing assembly can realize the integration of substrate unwinding and hot pressing, and simultaneously complete the tension control of the film forming template when pre-fixing the fiber skeleton, with a linear speed of 10-20 m / min.

[0009] Furthermore, the pressure adjustment range of the hot pressing device is 0.2-0.4 MPa to avoid excessive pressure damaging the fiber skeleton structure, and the temperature adjustment range is 0-100℃. This enables the pre-fixation and template forming of the modified nanofiber skeleton.

[0010] Furthermore, the slit coating curtain is equipped with a dynamic viscosity-temperature compensation module and an infrared temperature measurement real-time feedback module, with an operating temperature field of 50-100℃. This effectively reduces the viscosity of the casting solution to improve its fluidity, ensuring sufficient filling of the nanofiber pores (reducing dead zones). Simultaneously, it promotes the in-situ reaction between the fiber and polyurethane, accelerating the formation of chemical bonds between the fiber's surface-active groups and the polyurethane, achieving simultaneous filling and cross-linking.

[0011] Furthermore, the slit application curtain has an adjustable gap structure with a gap range of 0.1-2.0 mm, and a piezoelectric ceramic sheet is embedded at the bottom edge of the slit for real-time compensation of gap offset. The embedded piezoelectric ceramic sheet (response time < 1 ms) compensates for gap offset caused by temperature changes (ΔT ± 5℃) or mechanical vibration in real time, ensuring that the slit width error is < ± 0.01 mm, thereby guaranteeing the penetration and filling of the bio-based polyurethane resin.

[0012] Furthermore, the multi-stage negative pressure module of the suction assembly can achieve regional gradient negative pressure, with the negative pressure range gradually increasing from 0.05 MPa to 0.5 MPa. This regional gradient negative pressure (0.05→0.3→0.5 MPa) adapts to the permeation resistance of different pore sizes, effectively improving filling efficiency.

[0013] Furthermore, the ultraviolet light source module of the ultraviolet rolling assembly employs multi-band synergistic irradiation, including UVA and UVC light sources. This activates the surface-active groups of the bio-based polyurethane resin photoinitiator and the scaffold fibers, respectively, enhancing the mechanical interlocking between them.

[0014] Furthermore, the ultraviolet light source template of the ultraviolet rolling assembly has a dual-band LED array, wherein the light intensity of the upper UVA (long-wave ultraviolet, 315-400nm) light source is 50-300 mW / cm². 2 Adjustable coverage width 100 mm; lower layer UVC (short-wave ultraviolet, 100-280nm) light source intensity 100-500 mW / cm² 2 Adjustable, the distance from the substrate can be adjusted from 20-50mm.

[0015] Furthermore, the pair of pressure rollers in the UV roll forming assembly are synchronously reverse-driven, with their rotational speeds matched at a ratio of 1:1.2 to 1:1.5. This synchronous reverse-driven operation adjusts the inter-roller pressure, achieving a dynamic balance between inter-roller pressure and shear force. This eliminates material buildup or fiber-drawing defects, effectively improving surface smoothness while preventing film damage caused by unidirectional friction.

[0016] Furthermore, in the pair of pressure rollers of the ultraviolet roller pressing assembly, the upper roller is a heating roller with an adjustable temperature not exceeding 80°C to prevent the casting liquid from solidifying and sticking on the roller surface, and the lower roller is a cooling roller with an adjustable temperature in the range of 10-25°C to ensure the pre-solidification of the casting liquid at a suitable cooling temperature, which is conducive to the formation of dense micropores on the film surface and improves the waterproof performance of the finished product.

[0017] This invention also provides a method for preparing a template-based bio-based microporous membrane, comprising the following steps: S1: The substrate is conveyed to the hot pressing assembly after passing through the substrate unwinding assembly and tension control assembly to pre-fix the modified nanofiber skeleton to form a template; S2: Bio-based polyurethane resin is applied to the template through a slit application curtain, and the resin is penetrated and filled into the template pores by the gradient negative pressure of the suction component. S3: Ultraviolet cross-linking is achieved through the ultraviolet light source of the ultraviolet rolling assembly, and rolling is performed through a pair of pressure rollers of the ultraviolet rolling assembly to realize the formation and surface optimization of microporous membrane.

[0018] Compared with the prior art, the present invention has the following advantages: (1) The synergistic effect of template formation and gradient negative pressure infiltration achieves efficient, deep, and uniform filling of nanoscale pores. Instead of simply using a template, a structurally stable modified nanofiber skeleton is first precisely formed using a hot pressing device as a "template," and then a multi-stage gradient negative pressure system of a suction device is used to actively guide the high-viscosity resin to infiltrate in a directional manner. This overcomes the problem of "uneven filling and dead corners" caused by high resin viscosity and differences in pore size in traditional impregnation or single negative pressure processes.

[0019] (2) In-situ simultaneous filling and crosslinking shortens the process and improves the mechanical properties of the product. A controllable temperature field (50-100℃) is set in the slit application and suction areas. This temperature not only reduces the resin viscosity but also simultaneously activates the active groups on the surface of the nanofibers and the bio-based polyurethane resin, prompting them to undergo a chemical reaction (in-situ crosslinking) during the filling process. This combines the traditional multi-step process of "filling first, then crosslinking" into one. This not only shortens the process but also enhances the interfacial bonding strength between the fiber and the resin at the molecular level, avoiding interlayer delamination and improving the mechanical properties of the final product.

[0020] (3) The integration of UV crosslinking and roll forming achieves surface smoothness and functional consistency of the membrane. The UV roll forming device integrates a multi-band UV light source (UVA / UVC) with a pair of synchronously reverse-driven rollers with a temperature difference (hot on top and cold on the bottom). UVA and UVC activate the resin and fiber respectively, enhancing the crosslinking effect (mechanical interlocking). The dual-roller design, through the precise coordination of pressure, shear force and temperature field, completes crosslinking, surface smoothing, pre-solidification and densification in one go, effectively eliminating surface defects such as material accumulation and fiber drawing, and ensuring the surface smoothness and functional consistency of the membrane.

[0021] (4) Intelligent and high-precision control throughout the entire process. The device integrates multiple high-precision control modules, such as dynamic viscosity-temperature compensation and piezoelectric ceramic gap compensation for the slit application curtain, and precise temperature control and pressure gradient adjustment for hot pressing and roller pressing. These control technologies ensure the stability and repeatability of the entire production process at high speed (10-20 m / min), and control the error of key process parameters (such as slit width) within a very small range (<±0.01mm), realizing precise and controllable product quality and laying the foundation for large-scale production. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a template-based bio-based microporous membrane coating device. Figure 2 This is a SEM image of the bio-based microporous membrane prepared in Example 2.

[0023] Reference numerals: 1-Substrate unwinding assembly, 2-Tension control assembly, 3-Hot pressing assembly, 4-Slit gluing curtain, 5-Suction assembly, 6-UV roller pressing assembly. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0025] Example 1 This embodiment provides a template-based bio-based microporous membrane coating device, such as... Figure 1 As shown, it includes a substrate unwinding assembly 1, a tension control assembly 2, a hot pressing assembly 3, a slot glue application curtain 4, a suction assembly 5, and an ultraviolet roller pressing assembly 6 arranged sequentially along the material conveying direction; The hot-pressing assembly 3 has a precision temperature control module and a pressure gradient adjustment module, which are used to pre-fix the modified nanofiber skeleton to form a template; The slit adhesive curtain 4 is used to permeate and fill the template with bio-based polyurethane resin. The suction component 5 has a multi-stage negative pressure module and a porous vacuum adsorption platform, which are used to realize the gradient negative pressure penetration and directional filling of resin in the template pores. The ultraviolet roll forming assembly 6 includes an ultraviolet light source module and a pair of pressure rollers, which are used to perform ultraviolet cross-linking and roll forming on the filled template.

[0026] The substrate unwinding assembly 1 and the hot pressing assembly 3 can realize the integration of substrate unwinding and hot pressing, and simultaneously complete the tension control of the film forming template when pre-fixing the fiber skeleton, with a linear speed of 10-20 m / min.

[0027] In a specific embodiment, the pressure adjustment range of the hot pressing device 3 is 0.2-0.4 MPa to avoid excessive pressure damaging the fiber skeleton structure, and the temperature adjustment range is 0-100℃. This enables the pre-fixation and template forming of the modified nanofiber skeleton.

[0028] In a specific embodiment, the slit coating curtain 4 is equipped with a dynamic viscosity-temperature compensation module and an infrared temperature measurement real-time feedback module, with a working temperature field of 50-100℃. This effectively reduces the viscosity of the casting solution to improve its fluidity, ensuring sufficient filling of the nanofiber pores (reducing dead zones). Simultaneously, it promotes the in-situ reaction between the fiber and polyurethane, accelerating the formation of chemical bonds between the fiber's surface-active groups and the polyurethane, thus simultaneously achieving filling and cross-linking.

[0029] In a specific embodiment, the slit adhesive application curtain 4 has an adjustable gap structure with a gap range of 0.1-2.0 mm, and a piezoelectric ceramic sheet is embedded at the bottom edge of the slit for real-time compensation of gap offset. The embedded piezoelectric ceramic sheet (response time < 1 ms) compensates for gap offset caused by temperature changes (ΔT ± 5℃) or mechanical vibration in real time, ensuring that the slit width error is < ± 0.01 mm, thereby guaranteeing the penetration and filling of the bio-based polyurethane resin.

[0030] In a specific embodiment, the multi-stage negative pressure module of the suction component 5 can achieve regional gradient negative pressure, with the negative pressure range gradually increasing from 0.05 MPa to 0.5 MPa. This regional gradient negative pressure (0.05→0.3→0.5 MPa) adapts to the permeation resistance of different pore sizes, effectively improving filling efficiency.

[0031] In a specific embodiment, the ultraviolet light source module of the ultraviolet rolling assembly 6 employs multi-band synergistic irradiation, including UVA and UVC light sources. This activates the surface-active groups of the bio-based polyurethane resin photoinitiator and the scaffold fibers, respectively, enhancing the mechanical interlocking between them.

[0032] In a specific embodiment, the ultraviolet light source template of the ultraviolet rolling assembly 6 has a dual-band LED array, wherein the light intensity of the upper UVA (long-wave ultraviolet, 315-400nm) light source is 50-300 mW / cm². 2 Adjustable coverage width 100 mm; lower layer UVC (short-wave ultraviolet, 100-280nm) light source intensity 100-500 mW / cm² 2 Adjustable, the distance from the substrate can be adjusted from 20-50mm.

[0033] In a specific embodiment, the pair of pressure rollers of the UV roll forming assembly 6 are synchronously reverse-driven, with the rotational speeds of the two rollers matched at a speed ratio of 1:1.2 to 1:1.5. The synchronous reverse-driven operation of the pair of pressure rollers in the UV roll forming assembly 6 adjusts the inter-roller pressure. Through the dynamic balance between inter-roller pressure and shear force, material accumulation or fiber-drawing defects are eliminated, effectively improving surface smoothness while avoiding film damage caused by unidirectional friction.

[0034] In a specific embodiment, the upper roller of the pair of rollers in the UV roller pressing assembly 6 is a heating roller with an adjustable temperature not exceeding 80°C to prevent the casting liquid from solidifying and sticking on the roller surface. The lower roller is a cooling roller with an adjustable temperature in the range of 10-25°C to ensure the pre-solidification of the casting liquid at a suitable cooling temperature, which is conducive to the formation of dense micropores on the film surface and improves the waterproof performance of the finished product.

[0035] This embodiment also provides a method for preparing a template-based bio-based microporous membrane, including the following steps: S1: The substrate is conveyed to the hot pressing assembly 3 after passing through the substrate unwinding assembly 1 and the tension control assembly 2 to pre-fix the modified nanofiber skeleton to form a template; S2: Bio-based polyurethane resin is applied to the template through the slit application curtain 4, and the resin is penetrated and filled into the template pores by the gradient negative pressure of the suction component 5. S3: Ultraviolet cross-linking is performed by the ultraviolet light source of the ultraviolet rolling assembly 6, and rolling is performed by a pair of pressure rollers of the ultraviolet rolling assembly 6 to achieve the formation and surface optimization of microporous membrane.

[0036] Example 2 This embodiment provides a template-based bio-based microporous membrane coating device, such as... Figure 1 As shown, it includes a substrate unwinding assembly 1, a tension control assembly 2, a hot pressing assembly 3, a slot glue application curtain 4, a suction assembly 5, and an ultraviolet roller pressing assembly 6 arranged sequentially along the material conveying direction; The hot-pressing assembly 3 has a precision temperature control module and a pressure gradient adjustment module, which are used to pre-fix the modified nanofiber skeleton to form a template; The slit adhesive curtain 4 is used to permeate and fill the template with bio-based polyurethane resin. The suction component 5 has a multi-stage negative pressure module and a porous vacuum adsorption platform, which are used to realize the gradient negative pressure penetration and directional filling of resin in the template pores. The ultraviolet roll forming assembly 6 includes an ultraviolet light source module and a pair of pressure rollers, which are used to perform ultraviolet cross-linking and roll forming on the filled template.

[0037] The substrate unwinding assembly 1 and the hot pressing assembly 3 simultaneously control the tension of the film-forming template while pre-fixing the fiber skeleton, and adjust the linear speed to 15 m / min.

[0038] The pressure of the hot-pressing assembly 3 is adjusted to 0.25 MPa, and the temperature is adjusted to 80℃.

[0039] The temperature field of the slit glue application curtain 4 and the suction assembly 5 is controlled at 80℃, the gap of the slit glue application curtain 4 is adjusted to 0.15mm, and the negative pressure of the suction assembly 5 is adjusted to 0.1-0.3MPa.

[0040] The ultraviolet light source module uses an upper-layer UVA light source (wavelength 365 nm, light intensity 100 mW / cm²). 2 ) and the underlying UVC light source (wavelength 254nm, light intensity 150 mW / cm²) 2 The composite light source is 20 mm away from the substrate.

[0041] The rotational speeds of the two rollers in the ultraviolet roller pressing assembly 6 are precisely matched according to a set speed ratio of 1:1.2. The upper roller is heated to 40°C, and the lower roller is cooled to 18°C.

[0042] This embodiment also provides a method for preparing a template-based bio-based microporous membrane, including the following steps: S1: The substrate is placed in the unwinding assembly 1 and conveyed to the hot pressing assembly 3 (0.25MPa, 80℃) via the tension control assembly 2 (15 m / min) to fix the modified nanofiber skeleton as a template for the bio-based microporous membrane. S2: Bio-based polyurethane resin is uniformly permeated and filled into the template through the slit application curtain 4 (gap 0.15mm, 80℃) and the suction component 5 (vacuum, negative pressure 0.1-0.3MPa, 80℃); the bio-based polyurethane resin is synthesized by introducing bio-based polyols derived from soybean oil into the molecular backbone, and its core physical properties are preserved through focused molecular structure design and process optimization.

[0043] S3: First, pass the ultraviolet light source template of the ultraviolet rolling assembly 6 (the upper layer uses a wavelength of 365 nm and a light intensity of 100 mW / cm). 2 The UVA light source has a lower layer with a distance of 20 mm from the substrate, a wavelength of 254 nm, and a light intensity of 150 mW / cm. 2 The UVC light source enables ultraviolet cross-linking of the bio-based microporous membrane. Finally, the template-based bio-based microporous membrane is formed and its surface optimized via a pair of rollers in the UV roller pressing assembly 6 (upper roller 40°C, lower roller 18°C, upper and lower roller speed ratio 1:1.2). Figure 2 This is a scanning electron microscope (SEM) image of the prepared bio-based microporous membrane.

[0044] Components not described in detail in this embodiment are all existing components that can be purchased through public channels.

[0045] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A template-based bio-based microporous membrane coating device, characterized in that, It includes a substrate unwinding assembly (1), a tension control assembly (2), a hot pressing assembly (3), a slot glue application curtain (4), a suction assembly (5), and an ultraviolet roller pressing assembly (6) arranged sequentially along the material conveying direction. The hot-pressing assembly (3) has a precision temperature control module and a pressure gradient adjustment module, which are used to pre-fix the modified nanofiber skeleton to form a template; The slit sealing curtain (4) is used to permeate and fill the template with bio-based polyurethane resin; The suction component (5) has a multi-stage negative pressure module and a porous vacuum adsorption platform, which are used to realize the gradient negative pressure penetration and directional filling of resin in the template pores; The ultraviolet roll forming assembly (6) includes an ultraviolet light source module and a pair of rollers for ultraviolet cross-linking and roll forming of the filled template.

2. The coating device for a template-based bio-based microporous membrane according to claim 1, characterized in that, The pressure adjustment range of the hot pressing device (3) is 0.2-0.4 MPa, and the temperature adjustment range is 0-100℃.

3. The coating device for a template-based bio-based microporous membrane according to claim 1, characterized in that, The slit application curtain (4) is equipped with a dynamic viscosity temperature compensation module and an infrared temperature measurement real-time feedback module, and its working temperature field is 50-100℃.

4. The coating device for a template-based bio-based microporous membrane according to claim 1, characterized in that, The slit adhesive curtain (4) has an adjustable gap structure with a gap range of 0.1-2.0 mm, and a piezoelectric ceramic sheet is embedded in the bottom edge of the slit to compensate for gap offset in real time, ensuring that the slit width error is less than ±0.01 mm.

5. The coating device for a template-based bio-based microporous membrane according to claim 1, characterized in that, The multi-stage negative pressure module of the suction component (5) can achieve regional gradient negative pressure, with the negative pressure range increasing from 0.05 MPa to 0.5 MPa.

6. The coating device for a template-based bio-based microporous membrane according to claim 1, characterized in that, The ultraviolet light source module of the ultraviolet roll forming assembly (6) adopts multi-band synergistic irradiation, including UVA light source and UVC light source.

7. The coating device for a template-based bio-based microporous membrane according to claim 6, characterized in that, The light intensity of the UVA light source is 50-300 mW / cm². 2 Adjustable, the light intensity of the UVC light source is 100-500 mW / cm². 2 Adjustable, the distance between the ultraviolet light source and the substrate is adjustable from 20-50 mm.

8. The coating device for a template-based bio-based microporous membrane according to claim 1, characterized in that, The pair of rollers of the ultraviolet roller pressing assembly (6) are driven synchronously in reverse, and the speeds of the two rollers are matched at a speed ratio of 1:1.2 to 1:1.

5.

9. The coating device for a template-based bio-based microporous membrane according to claim 1, characterized in that, The upper roller of the pair of rollers in the ultraviolet roller pressing assembly (6) is a heating roller with an adjustable temperature not exceeding 80°C, and the lower roller is a cooling roller with an adjustable temperature in the range of 10-25°C.

10. A method for preparing a template-based bio-based microporous membrane, using the coating apparatus according to any one of claims 1-9, characterized in that, Includes the following steps: S1: The substrate is conveyed to the hot pressing assembly (3) after passing through the substrate unwinding assembly (1) and tension control assembly (2) to pre-fix the modified nanofiber skeleton to form a template; S2: Bio-based polyurethane resin is applied to the template through the slit application curtain (4), and the resin is penetrated and filled into the template pores by the gradient negative pressure of the suction component (5). S3: Ultraviolet crosslinking is performed by the ultraviolet light source of the ultraviolet rolling assembly (6), and rolling is performed by a pair of rollers of the ultraviolet rolling assembly (6) to achieve the formation and surface optimization of the microporous membrane.

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