Preparation system and method of flat composite membrane

Abstract

The invention belongs to the field of material processing equipment, and discloses a preparation system and method of a flat composite membrane. The system comprises a film scraping device, a positioning gel device and a cleaning, drying and winding device, the membrane scraping device is used for coating a porous base material with a membrane casting solution, and the positioning and gelling device is used for positioning and gelling a primary composite membrane formed after coating of the membrane casting solution and comprises positioning equipment and a gelling tank; and the positioning equipment and the gel tank are sequentially arranged below the film scraping device. The system provided by the invention solves the problems that the coating thickness and uniformity of the two surfaces of a base material are difficult to control, the gelation process is unstable and the like during double-surface continuous and synchronous coating of a membrane casting solution with certain flowability and viscosity in the prior art, and can be applied on a large scale.

Description

Technical Field

[0001] The present invention belongs to the field of material processing equipment, and more specifically, relates to a system and method for preparing a flat composite membrane. Background Art

[0002] As a highly efficient separation material, separation membranes are widely used in sewage treatment and reuse, pure water production, chemical industry, seawater desalination, municipal water supply, electronics industry, pharmaceuticals and bioengineering, food, textiles and other fields, and the scale is gradually expanding. At present, commercial separation membranes are mainly in two forms: hollow fiber membranes and flat membranes. Flat membranes have outstanding advantages in anti-pollution and pressure resistance, and can be made into roll-type or plate-and-frame membrane components. Therefore, flat membranes are widely used under more special application conditions such as high driving pressure, high anti-pollution requirements, and less component filtration residue. Flat membranes prepared from conventional organic materials are divided into two categories: composite membranes and homogeneous membranes. The preparation methods of homogeneous flat membranes include melt-stretching method and coating method. The products of the melt-stretching method are mainly porous membranes of polyolefin materials, which are mostly used in lithium battery separators. The coating method is based on the principle of non-solvent induced phase separation. The main difference from the flat composite membrane is that the finished product has no support layer. The common method is to coat the casting liquid on the surface of the glass plate or metal plate, and then transfer the coated glass plate or metal plate to the coagulation bath to form a film. Although the method is simple to operate, it is difficult to prepare continuously. The size of the membrane is limited by the size of the glass plate or metal plate. Large glass plates or metal plates are not convenient to operate. Composite membranes are the main products of flat membranes. They are usually made by coating the casting liquid on the surface of supporting materials such as non-woven fabrics, and then forming a porous membrane through phase transformation. The mechanical strength of the membrane is effectively improved by the supporting material, which is conducive to long-term industrial applications. Common composite membranes are asymmetric single-sided composite materials, that is, the supporting material is located on one side of the membrane surface. There are certain differences in the performance of the two sides of the membrane. High-intensity backwashing cannot be performed during use, otherwise it is easy to cause the functional layer of the membrane to peel off. On the other hand, the existing double-sided coating technologies include secondary coating methods and synchronous coating methods. The secondary coating operation is difficult to control for a coating liquid with a certain fluidity. Synchronous coating also has the problem of difficult control of the uniformity of the coating thickness on both sides of the supporting material. In addition, during the solidification process, the coating layers on both sides of the membrane need to avoid contact with the guide roller to cause damage to the membrane surface, which is prone to jitter and affects the uniformity of the membrane. It cannot meet the preparation of composite membranes with high requirements for uniformity and symmetry on both sides.

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

[0004] CN113843940A discloses a device for double-sided coating of asphalt material on the surface of an isolation membrane, which is to coat the asphalt coiled material on both sides of the isolation membrane by two pressings, and is only applicable to the method in which the coating material has been formed. The method disclosed in CN114133881A is to coat the pressure-sensitive adhesive on both sides of the coated paper with a roller to roll back and forth to make the fiber cloth penetrate into the pressure-sensitive adhesive, and it is difficult to control the penetration position of the fiber cloth in the pressure-sensitive adhesive.

[0005] Therefore, it is urgent to propose a new preparation system for flat composite membranes. Summary of the invention

[0006] The purpose of the present invention is to provide a system and method for preparing a flat composite membrane in view of the shortcomings of the prior art. The system of the present invention solves the problems in the prior art that the coating thickness and uniformity on both sides of the substrate are difficult to control and the gel process is unstable when the casting liquid with certain fluidity and viscosity is continuously and synchronously coated on both sides, and can be applied on a large scale.

[0007] In order to achieve the above-mentioned object, the present invention provides a system for preparing a flat composite film, the system comprising a film scraping device, a gel positioning device, a cleaning, drying and winding device;

[0008] The film scraping device is used to apply the casting liquid to the porous substrate, and comprises a porous substrate channel, casting liquid channels on both sides, a casting liquid feed port, a sliding rod, a sliding scraper pair and a baffle;

[0009] The porous substrate channel is the internal gap formed between the sliding scraper pair; the baffles are respectively arranged on both sides of the outside of the sliding scraper pair, the sliding rod is used to adjust the relative horizontal movement of the sliding scraper pair and the baffle, and the casting liquid channels on both sides are respectively the gaps formed between the sliding scraper single piece and the baffle 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 of the bottom end of the lower gap matches the thickness of the porous substrate;

[0011] The inside of the casting liquid channels on both sides are provided with the casting liquid feed inlet, and the bottom is provided with a casting liquid discharge port;

[0012] The positioning gel device is used for positioning and gelling the primary composite film formed after coating the casting liquid, and comprises a positioning device and a gel tank; the positioning device and the gel tank are sequentially arranged below the film scraping device.

[0013] In the present invention, the sliding scraper pair includes two sliding scraper single pieces, and the porous substrate channel is an internal gap formed by the relative horizontal movement of the two sliding scraper single pieces under the action of the sliding 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 scraping device further comprises a first temperature control device for controlling the ambient temperature of the film casting liquid coating.

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

[0017] In the present invention, the spacing of the bottom end of the lower gap of the porous substrate channel matches the thickness of the porous substrate. The purpose of this setting is to prevent the porous substrate channel from damaging the porous substrate surface or causing the porous substrate to shake when passing through the porous substrate channel.

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

[0019] In the present invention, (1) the bottoms of the casting liquid channels on both sides are provided with casting liquid discharge ports, and the widths of the casting liquid discharge ports on both sides are the same, and (2) the casting liquid channels on both sides are provided with casting liquid feed ports, and the shapes and sizes of the casting liquid channels on both sides are the same, and the feed metering pump ensures that the feeding speeds of the casting liquid feed ports on both sides are the same (that is, the extrusion amounts of the casting liquid on both sides are consistent), thereby ensuring that 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 discharge ports on both sides are the same and are both smaller than the width of the porous substrate.

[0021] According to the present invention, preferably, the two sides of the casting liquid feed inlet are connected with a feed metering pump. In the present invention, as a preferred solution, the feed metering pump is 1 or 2, and the two sides of the casting liquid feed inlet can use one feed metering pump to feed simultaneously or two feed metering pumps to feed separately.

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

[0023] The positioning rollers are divided into two groups, which are respectively arranged on both sides of the width direction of the primary composite film after the casting liquid is coated and the part where the casting liquid is not coated. The two groups of positioning rollers are used to ensure that the primary composite film after the casting liquid is coated does not shake before entering the gel tank and forms an adjustable angle with the vertical direction;

[0024] The temperature atmosphere control sub-device is used to control the ambient temperature and atmosphere composition of the primary composite film coated with the casting liquid when the primary composite film passes through the positioning roller.

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

[0026] According to the present invention, preferably, each group of positioning roller pairs is at least one pair.

[0027] According to the present invention, preferably, the positioning roller pair is an active roller and / or a passive roller.

[0028] According to the present invention, preferably, the adjustable angle is -10° to 10°. In the present invention, the purpose of setting the adjustable angle is to reduce the liquid level fluctuation caused when the nascent composite membrane enters the gel liquid surface, further affecting the gel uniformity.

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

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

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

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

[0033] According to the present invention, preferably, 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 of the cleaning. The gelled primary composite film is transported and cleaned in the multi-stage cleaning tank through the cleaning guide roller.

[0034] According to the present invention, preferably, 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 of the drying environment.

[0035] According to the present invention, preferably, the material of the cleaning guide roller and the drying guide roller is independently 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 using the system comprising the following steps:

[0037] S1: passing the porous substrate through the porous substrate channel from top to bottom, and at the same time, passing the casting liquid through the casting liquid channels on both sides to coat the two opposite sides of the porous substrate, to obtain a primary composite membrane;

[0038] S2: using the positioning device of the positioning gel device to position the nascent composite membrane and send it into the gel tank for gel treatment to obtain the gelled nascent composite membrane, and sending it into the cleaning, drying and winding device for cleaning, drying and winding in sequence to obtain the flat composite membrane.

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

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

[0041] The feed metering pump ensures that the feed speeds of the casting liquid feed inlets on both sides are the same;

[0042] The coating speeds of the casting liquid in the casting liquid channels on both sides are independently 0-50 m / min. Preferably, the casting liquid in the casting liquid channels on both sides have 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° C., and the atmosphere composition when the nascent composite film passes through the positioning rollers is air with a humidity of 10-95RH% and / or nitrogen with a humidity of 10-95RH%;

[0046] The ambient temperature in the gel tank is -10°C to 80°C;

[0047] The cleaning environment temperature is 20-80°C;

[0048] The drying environment temperature is 40-150°C, and the drying ventilation volume is ≤1000m 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 the present invention can continuously prepare a composite membrane with uniform coating on both sides, the film-forming process of the membrane is easy to control, the thickness of the coating layer is uniform and controllable, the coating process is uniform and stable, the membrane surface is not damaged, and it is suitable for porous substrates of different thicknesses, and is suitable for a membrane-making system based on phase transformation film formation, and a composite membrane with symmetrical double-sided structure can be prepared. The system of the present invention is easy to control and operate, has high efficiency, and is convenient for industrial production. It can prepare ultrafiltration membranes, breathable membranes, ion exchange membranes, etc., and has broad application prospects in the fields of sewage treatment, material separation, biopharmaceuticals, medical care, new energy, etc.

[0052] The present invention uses two sliding scrapers of a sliding scraper pair to fix the porous substrate, and realizes continuous and uniform coating on both sides of the porous substrate with different thicknesses through the horizontal adjustment design of the baffle plates and the sliding scraper pair and the feeding control of the casting liquid channel, and the coating thickness on both sides is controllable.

[0053] The present invention uses a positioning pair of rollers to control the vibration of the nascent composite film, reducing the flow of the nascent composite film caused by the viscosity of the casting liquid and gravity before gelation, thereby solving the problem of uneven coating of the composite film sheet caused by the flow. The temperature atmosphere control sub-equipment used in the present invention can produce a pre-gelling effect on the nascent composite film, reduce the fluidity of the casting liquid, and stabilize the size of the film.

[0054] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0056] Figure 1 The schematic structural diagram of the film scraping device of the system for preparing a flat composite film provided by the present invention is shown.

[0057] FIG2 shows a schematic structural diagram of a positioning device in a positioning gel device of a system for preparing a flat composite membrane provided by the present invention ( FIG2( a ) is a front view; FIG2( b ) is a side view).

[0058] Figure 3 The schematic diagram of the structure of the gel tank in the positioning gel device of the system for preparing the flat composite membrane provided by the present invention is shown.

[0059] Figure 4The present invention shows a schematic structural diagram of a cleaning, drying and winding device of a flat composite membrane preparation system provided by the present invention.

[0060] The following are the descriptions of the reference numerals:

[0061] 1. Porous substrate channel; 2. Casting liquid channels on both sides; 3. Casting liquid feed port; 4. Sliding rod; 5. Sliding scraper pair; 6. Baffle; 7. Portion not coated with casting liquid; 8. Portion coated with casting liquid; 9. Positioning roller pair; 10. Primary composite film after coating with casting liquid; 11. Gel tank; 12. Gel guide roller; 13. Multi-stage cleaning tank; 14. Drying sub-device; 15. Winding sub-device. DETAILED DESCRIPTION

[0062] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0063] Example 1

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

[0065] The film scraping device is used to coat the porous substrate with a casting liquid, and comprises a porous substrate channel 1, casting liquid channels 2 on both sides, a casting liquid feed port 3, a sliding rod 4, a sliding scraper pair 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 arranged on both sides of the outside of the sliding scraper pair 5, the sliding rod 4 is used to adjust the relative horizontal movement of the sliding scraper pair 5 and the baffles 6, and the casting liquid channels 2 on both sides are respectively the gaps formed between the sliding scraper single piece 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, the cross section of the lower gap is a rectangle, and the length of the rectangle (i.e., the height from bottom to top of the relative parallel surface of the bottom end of the lower gap of the porous substrate channel 1) is 5 mm, and the spacing of the bottom end of the lower gap matches the thickness of the porous substrate;

[0068] The casting liquid channels 2 on both sides are provided with the casting liquid feed ports 3, and the bottoms are provided with casting liquid discharge ports; the widths of the casting liquid discharge ports on both sides are 10 μm, and the casting liquid feed ports 3 on both sides are connected to the same feed metering pump; in this embodiment, "the widths of the casting liquid discharge ports on both sides are consistent" and "the extrusion amounts of the casting liquid on both sides are consistent" can ensure uniform coating on both sides of the composite film.

[0069] At the same time, in the width direction of the porous substrate, the lengths of the casting liquid outlets on both sides are the same and are both 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 of the casting solution coating.

[0071] The positioning gel device is used for positioning and gelling the primary composite film formed after the casting liquid is coated, and comprises a positioning device, a gel tank 11, and a second temperature control device; the positioning device and the gel tank 11 are sequentially arranged below the film scraping device;

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

[0073] The positioning rollers 9 are divided into two groups, each group of positioning rollers is a pair, the positioning rollers 9 are active rollers, the positioning rollers 9 are made of stainless steel, and are respectively arranged on both sides of the width direction of the primary composite film after the casting liquid is coated and the part where the casting liquid is not coated, and the two groups of positioning rollers 9 are used to ensure that the primary composite film 10 after the casting liquid is coated does not shake before entering the gel tank 11 and forms an adjustable angle of -10° to 10° with the vertical direction;

[0074] The temperature atmosphere control sub-device is used to control the ambient temperature and atmosphere composition when the primary composite film 10 coated with the casting liquid passes through the positioning roller 9.

[0075] like Figure 3 As shown, the gel tank 11 is provided with gel liquid and a gel guide roller 12, and the gel guide roller 12 is used to transport the gelled primary 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 in the gel tank.

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

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

[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 for drying;

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

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

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

[0083] Among them, the ambient temperature of the casting liquid coating is 20°C;

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

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

[0086] Wherein, the conveying speed of the positioning roller 9 of the positioning device is 0.2m / min;

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

[0088] The ambient temperature in the gel tank 11 is -10°C;

[0089] The cleaning environment temperature is 20°C;

[0090] The drying environment temperature is 40°C, and the maximum ventilation volume of the drying is 1000m 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 the same, which is 0.2 m / min.

[0092] Example 2

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

[0094] The cross section of the lower gap of the porous substrate channel 1 is a rectangle, and the length of the rectangle (i.e., the height from bottom to top of the relative parallel surface at the bottom end of the lower gap of the porous substrate channel 1) is 10 mm;

[0095] The width of the casting liquid outlets on both sides is 1000 μm, and the two casting liquid feed ports 3 are respectively connected to respective feed metering pumps, that is, two feed metering pumps are used to feed respectively;

[0096] As shown in FIG. 2 , the positioning rollers 9 are divided into two groups, each group of positioning rollers has 4 pairs, and the material of the positioning rollers 9 is ceramic;

[0097] The material of the gel guide roller is ceramic;

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

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

[0100] S1: The porous substrate is a mesh cloth, and the porous substrate is passed through the porous substrate channel 1 from top to bottom, and the casting liquid is coated on two opposite sides of the porous substrate through the casting liquid channels 2 on both sides to obtain a primary composite membrane;

[0101] Among them, the ambient temperature of the casting liquid coating is 80°C;

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

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

[0104] Wherein, the conveying speed of the positioning roller 9 of the positioning device is 50m / min;

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

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

[0107] The cleaning environment temperature is 80°C;

[0108] The drying environment temperature is 150°C, and the maximum ventilation volume of the drying is 1000m 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 the same, which is 50 m / min.

[0110] Example 3

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

[0112] The cross section of the lower gap of the porous substrate channel 1 is a rectangle, and the length of the rectangle (i.e., the height from bottom to top of the relative parallel surface at the bottom end of the lower gap of the porous substrate channel 1) is 15 mm;

[0113] The width of the casting liquid outlets on both sides is 50 μm, and the two casting liquid feed ports 3 are connected to respective feed metering pumps, that is, two feed metering pumps are used to feed respectively;

[0114] The positioning rollers 9 are divided into two groups, each group of positioning rollers has 6 pairs, and the material of the positioning rollers 9 is polypropylene;

[0115] The material of the gel guide roller is polypropylene;

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

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

[0118] S1: The porous substrate is a mesh cloth, and the porous substrate is passed through the porous substrate channel 1 from top to bottom, and the casting liquid is coated on two opposite sides of the porous substrate through the casting liquid channels 2 on both sides to obtain a primary composite membrane;

[0119] Among them, the ambient temperature of the casting liquid coating is 25°C;

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

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

[0122] Wherein, the conveying speed of the positioning roller 9 of the positioning device is 10m / min;

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

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

[0125] The cleaning environment temperature is 60°C;

[0126] The drying environment temperature is 90°C, and the maximum ventilation volume of the drying is 1000m 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 the same, which is 10 m / min.

[0128] Example 4

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

[0130] The cross section of the lower gap of the porous substrate channel 1 is a rectangle, and the length of the rectangle (i.e., the height from bottom to top of the relative parallel surface at the bottom end of the lower gap of the porous substrate channel 1) is 30 mm;

[0131] The width of the casting liquid outlets on both sides is 500 μm, and the two casting liquid feed ports 3 are respectively connected to respective feed metering pumps, that is, two feed metering pumps are used to feed respectively;

[0132] The positioning rollers 9 are divided into two groups, each group of positioning rollers has three pairs, and the positioning rollers 9 are made of nylon;

[0133] The material of the gel guide roller is nylon;

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

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

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

[0137] Among them, the ambient temperature of the casting liquid coating is 30°C;

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

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

[0140] Wherein, the conveying speed of the positioning roller 9 of the positioning device is 10m / min;

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

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

[0143] The cleaning environment temperature is 60°C;

[0144] The drying environment temperature is 120°C, and the maximum ventilation volume of the drying is 1000m 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 the same, which is 10 m / min.

[0146] Example 5

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

[0148] The cross section of the lower gap of the porous substrate channel 1 is a rectangle, and the length of the rectangle (i.e., the height from bottom to top of the relative parallel surface at the bottom end of the lower gap of the porous substrate channel 1) is 25 mm;

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

[0150] The positioning rollers 9 are divided into two groups, each group of positioning rollers has 8 pairs, and the material of the positioning rollers 9 is polytetrafluoroethylene;

[0151] The material of the gel guide roller is polytetrafluoroethylene;

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

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

[0154] S1: The porous substrate is a mesh cloth, and the porous substrate is passed through the porous substrate channel 1 from top to bottom, and the casting liquid is coated on two opposite sides of the porous substrate through the casting liquid channels 2 on both sides to obtain a primary composite membrane;

[0155] Among them, the ambient temperature of the casting liquid coating is 25°C;

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

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

[0158] Wherein, the conveying speed of the positioning roller 9 of the positioning device is 15m / min;

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

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

[0161] The cleaning environment temperature is 80°C;

[0162] The drying environment temperature is 90°C, and the maximum ventilation volume of the drying is 1000m 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 the same, which is 15 m / min.

[0164] Test Case

[0165] This test example adopts GB / T 6672-2001 Determination of Thickness of Plastic Film and Thin Sheet - Mechanical Measurement Method to test the thickness of the composite film sheets prepared in Examples 1-5. The relative average deviation of 20 measurement data is calculated for each example and is listed in Table 1.

[0166] Table 1

[0167]

[0168] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes 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 membrane, characterized in that: The system includes a film scraping device, a gel positioning device, a cleaning, drying and winding device; The film scraping device is used to apply the casting liquid to the porous substrate, and comprises a porous substrate channel, casting liquid channels on both sides, a casting liquid feed port, a sliding rod, a sliding scraper pair and a baffle; The porous substrate channel is the internal gap formed between the sliding scraper pair; the baffles are respectively arranged on both sides of the outside of the sliding scraper pair, the sliding rod is used to adjust the relative horizontal movement of the sliding scraper pair and the baffle, and the casting liquid channels on both sides are respectively the gaps formed between the sliding scraper single piece and the baffle on both sides of the porous substrate channel; The upper gap of the porous substrate channel is larger than the lower gap, and the spacing of the bottom end of the lower gap matches the thickness of the porous substrate; The inside of the casting liquid channels on both sides are provided with the casting liquid feed inlet, and the bottom is provided with a casting liquid discharge port; The positioning gel device is used for positioning and gelling the primary composite film formed after coating the casting liquid, and comprises a positioning device and a gel tank; the positioning device and the gel tank are sequentially arranged below the film scraping device.

2. The system for preparing a flat composite membrane according to claim 1, wherein: The porous substrate is non-woven fabric and / or mesh fabric.

3. The system for preparing a flat composite membrane according to claim 1, wherein: The film scraping device also includes a first temperature control device for controlling the ambient temperature of the film casting liquid coating.

4. The system for preparing a flat composite membrane 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 system for preparing a flat composite membrane according to claim 1, wherein: The widths of the casting liquid discharge ports on both sides are the same and are smaller than the widths of the casting liquid channels on both sides. Preferably, the widths of the casting liquid discharge ports on both sides are 10-1000 μm. More preferably, the widths of the casting liquid discharge ports on both sides are 50-500 μm. In the width direction of the porous substrate, the lengths of the casting liquid outlets on both sides are the same and are both smaller than the width of the porous substrate; The casting liquid feed ports on both sides are connected with feed metering pumps.

6. The system for preparing a flat composite membrane according to claim 5, wherein: The positioning device includes a positioning roller pair and a temperature and atmosphere control sub-device; The positioning rollers are divided into two groups, which are respectively arranged on both sides of the width direction of the primary composite film after the casting liquid is coated and the part where the casting liquid is not coated. The two groups of positioning rollers are used to ensure that the primary composite film after the casting liquid is coated does not shake before entering the gel tank and forms an adjustable angle with the vertical direction; The temperature atmosphere control sub-device is used to control the ambient temperature and atmosphere composition of the primary composite film coated with the casting liquid when the primary composite film passes through the positioning roller.

7. The system for preparing a flat composite membrane according to claim 6, wherein: The positioning rollers are made of at least one of stainless steel, ceramic, polypropylene, nylon and polytetrafluoroethylene; Each set of positioning rollers shall consist of at least one pair; The positioning roller pair is an active roller and / or a passive roller; The adjustable angle is from -10° to 10°.

8. The system for preparing a flat composite membrane according to claim 1, wherein: The gel tank is provided with gel liquid and gel guide rollers, and the gel guide rollers are used to transport the gelled primary composite film to the cleaning, drying and winding device; The gel guide roller is made of at least one of stainless steel, ceramic, polypropylene, nylon and polytetrafluoroethylene.

9. The system for preparing a flat composite membrane according to claim 1, wherein: The gel positioning device also includes a second temperature control device for controlling the ambient temperature in the gel tank.

10. The system for preparing a flat composite membrane according to claim 1, wherein: The cleaning, drying and winding device comprises a cleaning sub-device, a drying sub-device and a winding sub-device; The cleaning sub-device includes 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 of the cleaning process; 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 independently at least one of stainless steel, ceramic, polypropylene, nylon and polytetrafluoroethylene.

11. A method for preparing a flat composite membrane, characterized in that: The method adopts the system according to any one of claims 1 to 10, comprising the following steps: S1: passing the porous substrate through the porous substrate channel from top to bottom, and at the same time, passing the casting liquid through the casting liquid channels on both sides to coat the two opposite sides of the porous substrate, to obtain a primary composite membrane; S2: using the positioning device of the positioning gel device to position the nascent composite membrane and send it into the gel tank for gel treatment to obtain the gelled nascent composite membrane, and sending it into the cleaning, drying and winding device for cleaning, drying and winding in sequence to obtain the flat composite membrane.

12. The method for preparing a flat composite membrane according to claim 11, wherein: In step S1: The ambient temperature for coating the casting liquid is 20-80℃; The feed metering pump ensures that the feed speeds of the casting liquid feed inlets on both sides are the same; The coating speeds of the casting liquid in the casting liquid channels on both sides are independently 0-50 m / min. Preferably, the casting liquid in the casting liquid channels on both sides have the same coating speed.

13. The method for preparing a flat composite membrane according to claim 11, wherein: In step S2: The conveying speed of the positioning rollers of the positioning device is 0-50m / min; The ambient temperature when the nascent composite film passes through the positioning rollers is 5-60° C., and the atmosphere composition when the nascent composite film passes through the positioning rollers is air with a humidity of 10-95 RH% and / or nitrogen with a humidity of 10-95 RH%; The ambient temperature in the gel tank is -10°C to 80°C; The cleaning environment temperature is 20-80°C; The drying environment temperature is 40-150°C, and the drying ventilation volume is ≤1000m 3 / h; 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.

Images