A system and method for preparing a flat composite film

Abstract

The application belongs to the field of material processing equipment, and discloses a preparation system and method of a flat plate composite film. The system comprises a film scraping device, a positioning gel device, a cleaning, drying and winding device; the film scraping device is used for casting film liquid coating on a porous base material; the positioning gel device is used for positioning and gelling of a nascent composite film formed after the casting film liquid coating, and comprises a positioning device and a gel tank; and the positioning device and the gel tank are sequentially arranged below the film scraping device. The system solves the problems in the prior art, such as difficulty in controlling the coating thickness and uniformity of both sides of the base material, instability of the gelling process and the like when continuously and synchronously coating the casting film liquid with certain fluidity and viscosity on both sides, and can be applied on a large scale.

Description

Technical Field

[0001] This invention belongs to the field of material processing equipment, and more specifically, relates to a system and method for preparing a flat composite film. Background Technology

[0002] Separation membranes, as highly efficient separation materials, are widely used in wastewater treatment and reuse, pure water production, chemical industry, seawater desalination, municipal water supply, electronics industry, pharmaceuticals and bioengineering, food, textiles, and other fields, and their scale is gradually expanding. Currently, commercially available separation membranes mainly come in two forms: hollow fiber membranes and flat sheet membranes. Flat sheet membranes have significant advantages in terms of antifouling and pressure resistance, and can be manufactured into spiral-wound or plate-and-frame membrane modules. Therefore, flat sheet membranes are more commonly used in applications requiring high driving pressure, high antifouling requirements, and minimal filtration residue. Flat sheet membranes prepared from conventional organic materials are divided into two main categories: composite membranes and homogeneous membranes. Homogeneous flat sheet membranes are prepared using melt-stretching and coating methods. Melt-stretching methods primarily produce porous membranes made of polyolefin materials, which are frequently used in lithium-ion battery separators. The coating method, based on the principle of solvent-free phase separation, differs from flat-sheet composite membranes primarily in that the finished product lacks a support layer. A common approach involves coating the casting solution onto the surface of a glass or metal plate, then transferring the coated plate to a coagulation bath to form the membrane. While simple to operate, this method is difficult to implement continuously, and the membrane size is limited by the size of the glass or metal plate; larger plates are inconvenient to handle. Composite membranes, the main product of flat-sheet membranes, typically involve coating the surface of a non-woven fabric or other supporting material with the casting solution, followed by phase inversion to form a porous membrane. The supporting material effectively improves the membrane's mechanical strength, which is beneficial for long-term industrial applications. Common composite membranes are asymmetric single-sided composite materials, meaning the support material is located on one side of the membrane surface, and the properties of the two sides of the membrane are somewhat different. High-intensity backwashing cannot be performed during use, otherwise the functional layer of the membrane is easily peeled off. On the other hand, existing double-sided coating technologies include two-stage coating methods and simultaneous coating methods. The two-stage coating operation is difficult to control for coating liquids with a certain degree of fluidity, and simultaneous coating also has the problem of difficulty in controlling the uniformity of coating thickness on both sides of the support material. In addition, during the solidification process, the coating layers on both sides of the membrane need to avoid contact with the guide rollers to avoid membrane surface damage, which can easily cause vibration and affect the uniformity of the membrane. Therefore, they cannot meet the requirements for the preparation of composite membranes with high requirements for uniformity and symmetry on both sides.

[0003] To address the aforementioned issues, some invention patents have proposed different methods for preparing double-sided coated composite membranes. CN114471166A discloses a method for preparing a modified layer on the surface of a polytetrafluoroethylene (PTFE) porous membrane by dip coating, which simultaneously coats both sides of the membrane with a modified layer. However, this method is difficult to control the coating thickness, especially when the coating liquid has a certain viscosity.

[0004] CN113843940A discloses an apparatus for coating asphalt material on both sides of a release liner, which involves coating the asphalt roll onto both sides of the release liner through two pressing processes. This method is only applicable to situations where the coating material is already formed. CN114133881A discloses a method that involves coating both sides of a coated paper with pressure-sensitive adhesive and then using rollers to repeatedly press the paper back and forth to allow the fiber cloth to penetrate into the pressure-sensitive adhesive. However, the penetration position of the fiber cloth into the pressure-sensitive adhesive is difficult to control.

[0005] Therefore, there is an urgent need to develop a new system for preparing flat composite membranes. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a system and method for preparing flat composite films. The system of this invention solves the problems in existing technologies, such as difficulty in controlling the coating thickness and uniformity on both sides of the substrate and instability in the gelation process when casting solutions with certain fluidity and viscosity are continuously and synchronously coated on both sides, enabling large-scale application.

[0007] To achieve the above objectives, the present invention provides a system for preparing a flat composite film, the system comprising a film scraping device, a positioning gel device, a washing, drying and winding device;

[0008] The coating device is used to coat a porous substrate with casting liquid, and includes a porous substrate channel, two sides of casting liquid channels, a casting liquid inlet, a slide bar, a pair of sliding scrapers and a baffle.

[0009] The porous substrate channel is the internal gap formed between the sliding scraper pair; the baffles are respectively disposed on the outer sides of the sliding scraper pair; the slide rod is used to adjust the relative horizontal movement of the sliding scraper pair and the baffles; the two casting liquid channels are the gaps formed between the sliding scraper blades and the baffles on both sides of the porous substrate channel.

[0010] The upper gap of the porous substrate channel is larger than the lower gap, and the spacing at the bottom of the lower gap matches the thickness of the porous substrate.

[0011] The casting liquid inlet is provided inside the casting liquid channel on both sides, and the casting liquid outlet is provided at the bottom of both sides.

[0012] The positioning and gelling device is used for positioning and gelling the nascent composite film formed after the casting solution is applied. It includes a positioning device and a gelling tank. The positioning device and the gelling tank are arranged sequentially below the film scraping device.

[0013] In this invention, the sliding scraper pair includes two sliding scraper blades, and the porous substrate channel is the internal gap formed between the two sliding scraper blades by their relative horizontal movement under the action of the slide rod.

[0014] According to the present invention, preferably, the porous substrate is a nonwoven fabric and / or a mesh fabric.

[0015] According to the present invention, preferably, the film-coating device further includes a first temperature control device for controlling the ambient temperature of the casting solution coating.

[0016] According to the present invention, preferably, the cross-section of the upper gap of the porous substrate channel is an inverted trapezoid, and the cross-section of the lower gap is a rectangle, and the length of the rectangle is ≥5mm, that is, the height of the relatively parallel plane at the bottom of the lower gap of the porous substrate channel from bottom to top is ≥5mm.

[0017] In this invention, the spacing at the bottom of the lower gap of the porous substrate channel is matched with the thickness of the porous substrate. The purpose of this setting is to avoid the porous substrate channel from damaging the surface of the porous substrate or causing the porous substrate to vibrate when passing through the porous substrate channel.

[0018] According to the present invention, preferably, the widths of the casting liquid outlets on both sides are the same and both are smaller than the widths of the casting liquid channels on both sides. Preferably, the widths of the casting liquid outlets on both sides are 10-1000 μm. More preferably, the widths of the casting liquid outlets on both sides are 50-500 μm.

[0019] In this invention, by (1) providing casting liquid outlets at the bottom of both casting liquid channels and having the same width at both casting liquid outlets, and (2) providing casting liquid inlets in both casting liquid channels and having the same shape and size in both casting liquid channels, and by ensuring that the feeding speed of the casting liquid inlets on both sides is the same (i.e., the casting liquid extrusion volume on both sides is consistent), the casting liquid channels on both sides have the same casting liquid coating speed.

[0020] According to the present invention, preferably, in the width direction of the porous substrate, the lengths of the casting liquid outlets on both sides are the same and both are smaller than the width of the porous substrate.

[0021] According to the present invention, preferably, the casting liquid inlets on both sides are connected to a metering pump. In the present invention, as a preferred embodiment, there are one or two metering pumps, and the casting liquid inlets on both sides can be supplied simultaneously by one metering pump or supplied separately by two metering pumps.

[0022] According to the present invention, preferably, the positioning device includes positioning rollers and a temperature and atmosphere control sub-device;

[0023] The positioning rollers are divided into two groups, which are respectively set on both sides of the width direction of the nascent composite film after the casting solution is coated and on the part that has not been coated with casting solution. The two groups of positioning rollers are used to ensure that the nascent composite film after the casting solution is coated does not vibrate before entering the gel tank and forms an adjustable angle with the vertical direction.

[0024] The temperature and atmosphere control sub-equipment is used to control the ambient temperature and atmosphere composition when the nascent composite film coated with the casting solution passes through the positioning rollers.

[0025] According to the present invention, preferably, the positioning rollers are made of at least one of stainless steel, ceramic, polypropylene, nylon and polytetrafluoroethylene.

[0026] According to the present invention, preferably, each group of positioning rollers consists of at least one pair.

[0027] According to the present invention, preferably, the positioning rollers are active rollers and / or passive rollers.

[0028] According to the present invention, preferably, the adjustable angle is -10° to 10°. In this invention, the purpose of setting the adjustable angle is to reduce surface fluctuations caused when the nascent composite membrane enters the gel solution, thereby reducing the impact on gel uniformity.

[0029] According to the present invention, preferably, the gel tank is provided with gel liquid and gel guide roller, the gel guide roller being used to convey the gelled nascent composite film to the cleaning, drying and winding device.

[0030] According to the present invention, preferably, the material of the gel guide roller is at least one selected from stainless steel, ceramic, polypropylene, nylon and polytetrafluoroethylene.

[0031] According to the present invention, preferably, the positioning gel device further includes a second temperature control device for controlling the ambient temperature inside the gel tank.

[0032] According to the present invention, preferably, the washing, drying and winding device includes a washing sub-device, a drying sub-device and a winding device.

[0033] According to the present invention, preferably, the cleaning sub-device includes a third temperature control device, a multi-stage cleaning tank, and cleaning guide rollers; the third temperature control device is used to control the ambient temperature during cleaning. The gelled nascent composite membrane is conveyed and cleaned in the multi-stage cleaning tank by the cleaning guide rollers.

[0034] According to the present invention, preferably, the drying sub-device includes a fourth temperature control device, a ventilation device, and a drying guide roller; the fourth temperature control device is used to control the ambient temperature during drying.

[0035] According to the present invention, preferably, the cleaning guide roller and the drying guide roller are each made of at least one of stainless steel, ceramic, polypropylene, nylon and polytetrafluoroethylene.

[0036] Another aspect of the present invention provides a method for preparing a flat composite membrane, the method employing the aforementioned system and comprising the following steps:

[0037] S1: The porous substrate is passed from top to bottom through the porous substrate channel, and the casting liquid is coated on the opposite sides of the porous substrate through the casting liquid channels on both sides to obtain the nascent composite film.

[0038] S2: The nascent composite film is positioned using the positioning device of the positioning gel device and sent into the gel tank for gel treatment to obtain the gelled nascent composite film. The gelled nascent composite film is then sent into the cleaning, drying and winding device for cleaning, drying and winding in sequence to obtain the flat composite film.

[0039] According to the present invention, preferably, in step S1:

[0040] The ambient temperature for casting solution coating is 20-80℃;

[0041] The feeding metering pump ensures that the feeding speed of the casting liquid inlets on both sides is the same;

[0042] The coating speed of the casting liquid in the two casting liquid channels is independently 0-50 m / min. Preferably, the casting liquid in the two casting liquid channels has the same coating speed.

[0043] According to the present invention, preferably, in step S2:

[0044] The conveying speed of the positioning rollers of the positioning device is 0-50m / min;

[0045] The ambient temperature when the nascent composite film passes through the positioning rollers is 5-60℃, and the atmosphere when the nascent composite film passes through the positioning rollers consists of air with a humidity of 10-95RH% and / or nitrogen with a humidity of 10-95RH%.

[0046] The ambient temperature inside the gel tank is -10℃ to 80℃;

[0047] The ambient temperature for the cleaning process is 20-80℃;

[0048] The drying environment temperature is 40-150℃, and the drying ventilation volume is ≤1000m³. 3 / h;

[0049] The winding speed of the winding device, the conveying speed of the cleaning guide roller, and the conveying speed of the drying guide roller are the same, which is 0-50m / min.

[0050] The beneficial effects of the technical solution of the present invention are as follows:

[0051] The system of this invention can continuously prepare composite membranes with uniform coating on both sides. The membrane formation process is easy to control, the coating thickness is uniform and controllable, the coating process is uniform and stable, and it does not damage the membrane surface. It is suitable for porous substrates of different thicknesses and for membrane formation systems based on phase inversion. It can prepare composite membranes with symmetrical double-sided structures. The system of this invention is easy to control and operate, highly efficient, and convenient for industrial production. It can prepare ultrafiltration membranes, permeable membranes, ion exchange membranes, etc., and has broad application prospects in wastewater treatment, material separation, biopharmaceuticals, medical and health care, new energy and other fields.

[0052] This invention utilizes two sliding blades of a sliding blade pair to fix a porous substrate. Through the horizontal adjustment design of the side baffles and the sliding blade pair, as well as the feeding control of the casting liquid channel, continuous and uniform two-sided coating of porous substrates of different thicknesses is achieved, with controllable coating thickness on both sides.

[0053] This invention employs positioning rollers to control the vibration of the nascent composite membrane, reducing the flow of the nascent composite membrane caused by the viscosity of the casting solution and gravity before gelation, thereby solving the problem of uneven coating of the composite membrane caused by flow. The temperature and atmosphere control sub-equipment used in this invention can induce pre-gelation of the nascent composite membrane, reducing the fluidity of the casting solution and stabilizing the membrane size.

[0054] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0055] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0056] Figure 1 A schematic diagram of the film-scraping device of a flat composite film preparation system provided by the present invention is shown.

[0057] Figure 2 shows a schematic diagram of the positioning device in the positioning gel device of the preparation system of a flat composite film provided by the present invention (Figure 2(a) is a front view; Figure 2(b) is a side view).

[0058] Figure 3 A schematic diagram of the gel tank in the positioning gel device of a flat composite membrane preparation system provided by the present invention is shown.

[0059] Figure 4A schematic diagram of the cleaning, drying, and winding device of a flat composite film preparation system provided by the present invention is shown.

[0060] The annotations in the attached figures are explained as follows:

[0061] 1. Porous substrate channel; 2. Casting solution channels on both sides; 3. Casting solution inlet; 4. Slide bar; 5. Sliding scraper pair; 6. Baffle; 7. Part not coated with casting solution; 8. Part coated with casting solution; 9. Positioning rollers; 10. Initial composite film after casting solution coating; 11. Gel tank; 12. Gel guide roller; 13. Multi-stage cleaning tank; 14. Drying sub-device; 15. Winding device. Detailed Implementation

[0062] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0063] Example 1

[0064] This embodiment provides a system for preparing a flat composite film, such as... Figure 1-4 As shown, the system includes a film scraping device, a positioning gel device, a washing, drying, and winding device;

[0065] The coating device is used to coat a porous substrate with casting liquid, and includes a porous substrate channel 1, two casting liquid channels 2 on both sides, a casting liquid inlet 3, a slide bar 4, a pair of sliding scrapers 5, a baffle 6, and a first temperature control device (not shown).

[0066] like Figure 1 As shown, the porous substrate channel 1 is the internal gap formed between the sliding scraper pair 5; the baffles 6 are respectively disposed on the outer sides of the sliding scraper pair 5; the slide rod 4 is used to adjust the relative horizontal movement of the sliding scraper pair 5 and the baffles 6; the two casting liquid channels 2 are the gaps formed between the sliding scraper blades and the baffles 6 on both sides of the porous substrate channel 1.

[0067] The upper gap of the porous substrate channel 1 is larger than the lower gap. The cross-section of the upper gap is an inverted trapezoid, and the cross-section of the lower gap is a rectangle. The length of the rectangle (i.e., the height of the relatively parallel plane at the bottom of the lower gap of the porous substrate channel 1 from bottom to top) is 5 mm. The spacing at the bottom of the lower gap matches the thickness of the porous substrate.

[0068] The casting liquid channels 2 on both sides are provided with casting liquid inlets 3 and casting liquid outlets at the bottom; the width of the casting liquid outlets on both sides is 10μm, and the casting liquid inlets 3 on both sides are connected to the same feeding metering pump; in this embodiment, "the width of the casting liquid outlets on both sides is the same" and "the extrusion amount of casting liquid on both sides is the same" can ensure that the coating on both sides of the composite film is uniform.

[0069] Meanwhile, in the width direction of the porous substrate, the lengths of the casting liquid outlets on both sides are the same and both are smaller than the width of the porous substrate, so as to position the gel device.

[0070] The first temperature control device is used to control the ambient temperature for coating the casting solution.

[0071] The positioning and gelling device is used for positioning and gelling the nascent composite film formed after the casting solution is coated. It includes a positioning device, a gelling tank 11, and a second temperature control device. The positioning device and the gelling tank 11 are sequentially arranged below the film scraping device.

[0072] The positioning device includes positioning rollers 9 and a temperature and atmosphere control sub-device;

[0073] The positioning rollers 9 are divided into two groups, with one pair in each group. The positioning rollers 9 are active rollers. The positioning rollers 9 are made of stainless steel and are respectively set on both sides of the width direction of the nascent composite film after the casting solution is applied, in the part that has not been coated with casting solution. The two groups of positioning rollers 9 are used to ensure that the nascent composite film 10 after the casting solution is applied does not vibrate before entering the gel tank 11 and forms an adjustable angle of -10° to 10° in the vertical direction.

[0074] The temperature and atmosphere control sub-equipment is used to control the ambient temperature and atmosphere composition of the nascent composite film 10 after the casting solution is coated as it passes through the positioning rollers 9.

[0075] like Figure 3 As shown, the gel tank 11 is provided with gel liquid and gel guide roller 12. The gel guide roller 12 is used to transport the gelled nascent composite film to the cleaning, drying and winding device. The gel guide roller is made of stainless steel.

[0076] The second temperature control device is used to control the ambient temperature inside the gel tank.

[0077] like Figure 4 As shown, the washing, drying and winding device includes a washing sub-device, a drying sub-device 14 and a winding device 15;

[0078] The cleaning sub-device includes a third temperature control device, a multi-stage cleaning tank 13, and cleaning guide rollers; the third temperature control device is used to control the ambient temperature during cleaning.

[0079] The drying sub-device 14 includes a fourth temperature control device, a ventilation device, and a drying guide roller; the fourth temperature control device is used to control the ambient temperature during drying.

[0080] Both the cleaning guide roller and the drying guide roller are made of stainless steel.

[0081] The preparation of flat-sheet composite membranes using the above system includes the following steps:

[0082] S1: The porous substrate is a non-woven fabric. The porous substrate is passed from top to bottom through the porous substrate channel 1, and the casting liquid is coated on the opposite sides of the porous substrate through the casting liquid channels 2 on both sides to obtain a nascent composite film.

[0083] The ambient temperature for coating with the casting solution is 20℃.

[0084] The casting liquid in the casting liquid channels 2 on both sides has the same coating speed of 0.2 m / min;

[0085] S2: The positioning device of the positioning gel device is used to position the nascent composite film and send it into the gel tank 11 for gel treatment to obtain the gelled nascent composite film. The film is then sent into the cleaning, drying and winding device for cleaning, drying and winding in sequence to obtain the flat composite film.

[0086] The positioning roller 9 of the positioning device has a conveying speed of 0.2 m / min;

[0087] The ambient temperature when the nascent composite film passes through the positioning rollers 9 is 5°C, and the atmosphere when the nascent composite film passes through the positioning rollers 9 is air with a humidity of 10%RH.

[0088] The ambient temperature inside the gel tank 11 is -10℃;

[0089] The ambient temperature for the cleaning process is 20°C.

[0090] The drying environment temperature is 40℃, and the maximum ventilation volume is 1000m³. 3 / h;

[0091] The winding speed of the winding device 15, the conveying speed of the cleaning guide roller, and the conveying speed of the drying guide roller are all the same, which is 0.2 m / min.

[0092] Example 2

[0093] This embodiment provides a system for preparing a flat composite film, such as... Figure 1-4 As shown, the only difference between this embodiment and Embodiment 1 is that:

[0094] The lower gap of the porous substrate channel 1 has a rectangular cross-section, and the length of the rectangle (i.e., the height of the bottommost parallel plane of the lower gap of the porous substrate channel 1 from bottom to top) is 10 mm.

[0095] The width of the casting liquid outlets on both sides is 1000μm. The two casting liquid inlets 3 are respectively connected to their respective feeding metering pumps, that is, two feeding metering pumps are used to feed the liquid separately.

[0096] As shown in Figure 2, the positioning rollers 9 are divided into two groups, with 4 pairs of positioning rollers in each group. The positioning rollers 9 are made of ceramic.

[0097] The gel guide roller is made of ceramic.

[0098] Both the cleaning guide roller and the drying guide roller are made of ceramic.

[0099] The preparation of flat-sheet composite membranes using the above system includes the following steps:

[0100] S1: The porous substrate is a mesh fabric. The porous substrate is passed from top to bottom through the porous substrate channel 1, and the casting liquid is coated on the opposite sides of the porous substrate through the casting liquid channels 2 on both sides to obtain a nascent composite film.

[0101] The ambient temperature for coating the casting solution is 80℃;

[0102] The casting liquid in the casting liquid channels 2 on both sides has the same coating speed of 50m / min;

[0103] S2: The positioning device of the positioning gel device is used to position the nascent composite film and send it into the gel tank 11 for gel treatment to obtain the gelled nascent composite film. The film is then sent into the cleaning, drying and winding device for cleaning, drying and winding in sequence to obtain the flat composite film.

[0104] The positioning roller 9 of the positioning device has a conveying speed of 50m / min;

[0105] The ambient temperature when the nascent composite film passes through the positioning rollers 9 is 60°C, and the atmosphere when the nascent composite film passes through the positioning rollers 9 is air with a humidity of 95%RH.

[0106] The ambient temperature inside the gel tank 11 is 80°C;

[0107] The ambient temperature for the cleaning process is 80°C.

[0108] The drying environment temperature is 150℃, and the maximum ventilation volume is 1000m³. 3 / h;

[0109] The winding speed of the winding device 15, the conveying speed of the cleaning guide roller, and the conveying speed of the drying guide roller are all the same, which is 50 m / min.

[0110] Example 3

[0111] This embodiment provides a system for preparing a flat composite film, such as... Figure 1-4 As shown, the only difference between this embodiment and Embodiment 1 is that:

[0112] The lower gap of the porous substrate channel 1 has a rectangular cross-section, and the length of the rectangle (i.e., the height of the bottommost parallel plane of the lower gap of the porous substrate channel 1 from bottom to top) is 15mm.

[0113] The width of the casting liquid outlets on both sides is 50μm. The two casting liquid inlets 3 are respectively connected to their respective feeding metering pumps, that is, two feeding metering pumps are used to feed the liquid separately.

[0114] The positioning rollers 9 are divided into two groups, with 6 pairs of positioning rollers in each group. The positioning rollers 9 are made of polypropylene.

[0115] The gel guide roller is made of polypropylene;

[0116] Both the cleaning guide roller and the drying guide roller are made of polypropylene.

[0117] The preparation of flat-sheet composite membranes using the above system includes the following steps:

[0118] S1: The porous substrate is a mesh fabric. The porous substrate is passed from top to bottom through the porous substrate channel 1, and the casting liquid is coated on the opposite sides of the porous substrate through the casting liquid channels 2 on both sides to obtain a nascent composite film.

[0119] The ambient temperature for coating the casting solution is 25℃.

[0120] The casting liquid in the casting liquid channels 2 on both sides has the same coating speed of 10m / min;

[0121] S2: The positioning device of the positioning gel device is used to position the nascent composite film and send it into the gel tank 11 for gel treatment to obtain the gelled nascent composite film. The film is then sent into the cleaning, drying and winding device for cleaning, drying and winding in sequence to obtain the flat composite film.

[0122] The positioning roller 9 of the positioning device has a conveying speed of 10m / min;

[0123] The ambient temperature when the nascent composite film passes through the positioning roller 9 is 25°C, and the atmosphere when the nascent composite film passes through the positioning roller 9 is nitrogen with a humidity of 50%RH.

[0124] The ambient temperature inside the gel tank 11 is 30°C;

[0125] The ambient temperature for the cleaning process is 60°C.

[0126] The drying environment temperature is 90℃, and the maximum ventilation volume is 1000m³. 3 / h;

[0127] The winding speed of the winding device 15, the conveying speed of the cleaning guide roller, and the conveying speed of the drying guide roller are all the same, which is 10m / min.

[0128] Example 4

[0129] This embodiment provides a system for preparing a flat composite film, such as... Figure 1-4 As shown, the only difference between this embodiment and Embodiment 1 is that:

[0130] The lower gap of the porous substrate channel 1 has a rectangular cross-section, and the length of the rectangle (i.e., the height of the bottommost parallel plane of the lower gap of the porous substrate channel 1 from bottom to top) is 30mm.

[0131] The width of the casting liquid outlets on both sides is 500μm. The two casting liquid inlets 3 are respectively connected to their respective metering pumps, that is, two metering pumps are used to supply the liquid separately.

[0132] The positioning rollers 9 are divided into two groups, with 3 pairs in each group. The material of the positioning rollers 9 is nylon.

[0133] The gel guide roller is made of nylon;

[0134] Both the cleaning guide roller and the drying guide roller are made of nylon.

[0135] The preparation of flat-sheet composite membranes using the above system includes the following steps:

[0136] S1: The porous substrate is a non-woven fabric. The porous substrate is passed from top to bottom through the porous substrate channel 1, and the casting liquid is coated on the opposite sides of the porous substrate through the casting liquid channels 2 on both sides to obtain a nascent composite film.

[0137] The ambient temperature for coating the casting solution is 30℃.

[0138] The casting liquid in the casting liquid channels 2 on both sides has the same coating speed of 10m / min;

[0139] S2: The positioning device of the positioning gel device is used to position the nascent composite film and send it into the gel tank 11 for gel treatment to obtain the gelled nascent composite film. The film is then sent into the cleaning, drying and winding device for cleaning, drying and winding in sequence to obtain the flat composite film.

[0140] The positioning roller 9 of the positioning device has a conveying speed of 10m / min;

[0141] The ambient temperature when the nascent composite film passes through the positioning rollers 9 is 30°C, and the atmosphere when the nascent composite film passes through the positioning rollers 9 is air with a humidity of 50%RH.

[0142] The ambient temperature inside the gel tank 11 is 40°C;

[0143] The ambient temperature for the cleaning process is 60°C.

[0144] The drying environment temperature is 120℃, and the maximum ventilation volume is 1000m³. 3 / h;

[0145] The winding speed of the winding device 15, the conveying speed of the cleaning guide roller, and the conveying speed of the drying guide roller are all the same, which is 10m / min.

[0146] Example 5

[0147] This embodiment provides a system for preparing a flat composite film, such as... Figure 1-4 As shown, the only difference between this embodiment and Embodiment 1 is that:

[0148] The lower gap of the porous substrate channel 1 has a rectangular cross-section, and the length of the rectangle (i.e., the height of the bottommost parallel plane of the lower gap of the porous substrate channel 1 from bottom to top) is 25mm.

[0149] The width of the casting liquid outlets on both sides is 150μm. The two casting liquid inlets 3 are respectively connected to their respective metering pumps, that is, two metering pumps are used to supply the liquid separately.

[0150] The positioning rollers 9 are divided into two groups, with 8 pairs in each group. The material of the positioning rollers 9 is polytetrafluoroethylene.

[0151] The gel guide roller is made of polytetrafluoroethylene;

[0152] Both the cleaning guide roller and the drying guide roller are made of polytetrafluoroethylene.

[0153] The preparation of flat-sheet composite membranes using the above system includes the following steps:

[0154] S1: The porous substrate is a mesh fabric. The porous substrate is passed from top to bottom through the porous substrate channel 1, and the casting liquid is coated on the opposite sides of the porous substrate through the casting liquid channels 2 on both sides to obtain a nascent composite film.

[0155] The ambient temperature for coating the casting solution is 25℃.

[0156] The casting liquid in the casting liquid channels 2 on both sides has the same coating speed of 15m / min;

[0157] S2: The positioning device of the positioning gel device is used to position the nascent composite film and send it into the gel tank 11 for gel treatment to obtain the gelled nascent composite film. The film is then sent into the cleaning, drying and winding device for cleaning, drying and winding in sequence to obtain the flat composite film.

[0158] The positioning roller 9 of the positioning device has a conveying speed of 15m / min;

[0159] The ambient temperature when the nascent composite film passes through the positioning roller 9 is 25°C, and the atmosphere when the nascent composite film passes through the positioning roller 9 is nitrogen with a humidity of 50%RH.

[0160] The ambient temperature inside the gel tank 11 is 80°C;

[0161] The ambient temperature for the cleaning process is 80°C.

[0162] The drying environment temperature is 90℃, and the maximum ventilation volume is 1000m³. 3 / h;

[0163] The winding speed of the winding device 15, the conveying speed of the cleaning guide roller, and the conveying speed of the drying guide roller are all the same, which is 15 m / min.

[0164] Test case

[0165] This test example uses GB / T 6672-2001 Determination of thickness of plastic films and sheets - Mechanical measurement method to test the thickness of the composite films prepared in Examples 1-5. The relative average deviation of the measurement data of each example is calculated for 20 times and is listed in Table 1.

[0166] Table 1

[0167]

[0168] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A system for preparing a flat composite film, characterized by comprising: The system comprises a blade coating device, a positioning gel device, a cleaning and drying and winding device; The blade coating device is used for casting film solution coating on a porous substrate, and comprises a porous substrate channel, two side casting film solution channels, a casting film solution feeding port, a sliding rod, a sliding doctor blade pair and a baffle; The porous substrate channel is an internal gap formed between the sliding doctor blade pair, the baffles are respectively arranged on the outer sides of the sliding doctor blade pair, the sliding rod is used for adjusting the relative horizontal movement of the sliding doctor blade pair and the baffles, and the two side casting film solution channels are gaps respectively formed between the sliding doctor blade single pieces and the baffles on the two sides of the porous substrate channel; The upper gap of the porous substrate channel is larger than the lower gap, and the distance of the bottom end of the lower gap matches the thickness of the porous substrate; The internal part of the two side casting film solution channels is respectively provided with the casting film solution feeding port, and the bottom part is respectively provided with a casting film solution discharging port; The positioning gel device is used for positioning and gelling of the nascent composite film formed after the casting film solution coating, and comprises a positioning equipment and a gel tank; the positioning equipment and the gel tank are sequentially arranged below the blade coating device; The positioning equipment comprises a positioning roller pair; the positioning roller pair is divided into two groups and is respectively arranged on the two sides of the nascent composite film in the width direction after the casting film solution coating and the part not subjected to the casting film solution coating, and the two groups of positioning roller pairs are used for ensuring that the nascent composite film after the casting film solution coating does not shake and forms an adjustable angle with the vertical direction before entering the gel tank.

2. The flat sheet composite membrane preparation system according to claim 1, wherein, The porous substrate is non-woven fabric and / or grid cloth.

3. The flat sheet composite membrane preparation system according to claim 1, wherein, The blade coating device further comprises a first temperature control equipment for controlling the environmental temperature of the casting film solution coating.

4. The flat sheet composite membrane preparation system according to claim 1, wherein, The cross section of the upper gap of the porous substrate channel is an inverted trapezoid, and the cross section of the lower gap is a rectangle, and the length of the rectangle is ≥5 mm.

5. The flat sheet composite membrane preparation system according to claim 1, wherein, The widths of the two side casting film solution discharging ports are the same and are smaller than the widths of the two side casting film solution channels; In the width direction of the porous substrate, the lengths of the two side casting film solution discharging ports are the same and are smaller than the width of the porous substrate; The two side casting film solution feeding ports are connected with feeding metering pumps.

6. The flat sheet composite membrane preparation system according to claim 5, wherein, The widths of the two side casting film solution discharging ports are 10-1000 μm.

7. The flat sheet composite membrane preparation system according to claim 6, wherein, The widths of the two side casting film solution discharging ports are 50-500 μm.

8. The flat sheet composite membrane preparation system according to claim 5, wherein, The positioning equipment comprises a temperature atmosphere control sub-equipment; The temperature atmosphere control sub-equipment is used for controlling the environmental temperature and atmosphere composition when the nascent composite film after the casting film solution coating passes through the positioning roller pair.

9. The flat sheet composite membrane preparation system according to claim 8, wherein, The material of the positioning roller pair is at least one of stainless steel, ceramic, polypropylene, nylon and polytetrafluoroethylene; Each group of positioning roller pairs is at least one pair; The positioning roller pair is a driving roller and / or a driven roller; The adjustable angle is -10° to 10°.

10. The flat sheet composite membrane preparation system of claim 1, wherein, The gel tank is provided with a gel liquid and a gel guide roller, and the gel guide roller is used for conveying the nascent composite film after gelling to the cleaning and drying and winding device; The material of the gel guide roller is at least one of stainless steel, ceramic, polypropylene, nylon and polytetrafluoroethylene.

11. The flat sheet composite membrane preparation system of claim 1, wherein, The positioning gel device further comprises a second temperature control equipment for controlling the environmental temperature in the gel tank.

12. The flat sheet composite membrane preparation system of claim 1, wherein, The cleaning and drying and winding device comprises a cleaning sub-device, a drying sub-device and a winding sub-device; The cleaning sub-device comprises a third temperature control device, a multi-stage cleaning tank and a cleaning guide roller; the third temperature control device is used to control the ambient temperature for cleaning; The drying sub-device comprises a fourth temperature control device, a ventilation device and a drying guide roller; the fourth temperature control device is used to control the ambient temperature for drying; The material of the cleaning guide roller and the drying guide roller is at least one of stainless steel, ceramic, polypropylene, nylon and polytetrafluoroethylene.

13. A method of preparing a flat sheet composite membrane, characterized by, The method adopts the system according to any one of claims 1-12, comprising the following steps: S1: passing the porous substrate from top to bottom through the porous substrate channel, while making the casting solution pass through the two-side casting solution channels to coat the opposite two sides of the porous substrate, to obtain a nascent composite film; S2: positioning the nascent composite film by the positioning device of the positioning gel device and sending it into the gel tank for gel processing to obtain a gelled nascent composite film, and then sending it into the cleaning, drying and winding device for cleaning, drying and winding in sequence to obtain the flat plate composite film.

14. The method of claim 13, wherein, In step S1: The ambient temperature for casting solution coating is 20-80℃; The feed metering pump ensures the same feed speed of the two-side casting solution feed inlets; The coating speed of the casting solution in the two-side casting solution channels is independently 0-50m / min.

15. The method of claim 14, wherein, The casting solution in the two-side casting solution channels has the same coating speed.

16. The method of making a flat sheet composite film according to claim 13, wherein, In step S2: The conveying speed of the positioning nip roller of the positioning device is 0-50m / min; The ambient temperature when the nascent composite film passes through the positioning nip roller is 5-60℃, and the atmosphere composition when the nascent composite film passes through the positioning nip roller is air with humidity of 10-95 RH% and / or nitrogen with humidity of 10-95 RH%; The ambient temperature in the gel tank is -10℃ to 80℃; The ambient temperature for cleaning is 20-80℃; The drying environment temperature is 40-150°C, and the drying ventilation volume is ≤1000 m 3 / h; The winding speed of the winding sub-device, the conveying speed of the cleaning guide roller and the conveying speed of the drying guide roller are the same, being 0-50m / min.

Images