An ultrathin film assembly

Abstract

The present application relates to the field of water treatment filter medium, in particular to a kind of ultra-thin soft film assembly, comprising: film-coated plate, ultra-thin soft film, flow guide net, the thickness direction two sides of flow guide net are symmetrically provided with ultra-thin soft film, and the outer side of the ultra-thin soft film away from flow guide net is provided with film-coated plate. Ultra-thin soft film is used, and the direct filtration effect is good, the resistance is small, and the power consumption is low. Ultra-thin soft film is covered on film-coated plate, adjacent two pieces of ultra-thin soft film are bonded due to the pulling force of water, and the speed of particles in sewage tank impacting membrane is also blocked, to prevent the damage of ultra-thin soft film microporous structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water treatment filter media, in particular to a kind of ultra-thin soft film assembly. BACKGROUND

[0002] At present, the filter membrane for filtering sewage tank generally has two kinds;The first kind is PVDF material, and the thickness is 100-150um, and the second kind is PVDF material, and the thickness is 40-100um;The first kind can rely on the support of the film thickness, and when forming the soft film assembly, it can exist in the form of filter membrane-mesh-filter membrane without support plate structure, and the second kind needs to be set in the middle support plate due to the thin thickness compared with the first kind, forming the inner support structure of filter membrane-mesh-support plate-mesh-filter membrane.

[0003] The common problem of the above two kinds of filter membrane assemblies is that the filter membrane is too thick, which forms resistance to filtration, thereby causing waste of pollution resistance and energy consumption.

[0004] Although it is known that ultra-thin filter membranes such as polyolefin base membranes also have filtering function, sewage tank often contains particulate impurities, which will impact the surface of the filter membrane under the action of aeration agitation, and the particulate impurities will scratch the surface of the filter membrane, affect the filtering effect, cause damage to the micro-porous structure of the filter membrane, and even cause the part to be scrapped, so the industry generally believes that ultra-thin filter membranes are not suitable for sewage tank treatment environment. SUMMARY

[0005] In view of the existing technical problems, the present application provides an ultra-thin soft film assembly, which makes it possible to apply ultra-thin soft film to sewage aeration.

[0006] The present application adopts the following technical solutions:

[0007] An ultra-thin soft film assembly, comprising: a film-coated plate, an ultra-thin soft film, and a flow guide net, the ultra-thin soft film is symmetrically arranged on both sides of the thickness direction of the flow guide net, and the outer side of the ultra-thin soft film away from the flow guide net is provided with a film-coated plate.

[0008] The present application has the following advantages:

[0009] The present application adopts ultra-thin soft film, and does not need intermediate support layer, has good direct filtering effect, small resistance and low power consumption;The ultra-thin soft film is covered on the film-coated plate, which not only avoids the adhesion of adjacent two pieces of ultra-thin soft film due to the tensile strength of water, but also slows down the speed of particle impact on the film in the sewage tank, preventing the micro-porous structure of the ultra-thin soft film from being damaged. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 It is a three-dimensional schematic view of the structure of the embodiment of the present application;

[0011] Figure 2 Structure diagram of the film-coated plate of the present application;

[0012] Figure 3 Structure diagram of the flow guide net of the present application;

[0013] Figure 4 Structure diagram of the flow guide net and the ultra-thin soft film contact mode side of the present application;

[0014] Figure 5 Structure diagram of the regular mesh and the ultra-thin soft film contact mode of the present application;

[0015] Figure 6 Structure diagram of the ultra-thin soft film in the tight state of the present application;

[0016] Figure 7 Structure diagram of the ultra-thin soft film in the tight state of the present application;

[0017] Figure 8 Structure diagram of the ultra-thin soft film in the relaxed state of the present application;

[0018] Figure 9 Structure diagram of the ultra-thin soft film in the relaxed state of the present application;

[0019] Figure 10 Example of the ultra-thin soft film in the chemical pool environment of the present application - comparative example data details;

[0020] Figure 11 Example of the ultra-thin soft film in the wastewater pool environment of the present application - comparative example data details;

[0021] Figure 12 Structure diagram of the sample cutting method of the present application.

[0022] Reference signs:

[0023] 10 - film-coated plate; 11 - peripheral frame; 12 - inner frame; 13 - connecting bridge; 14 - reinforcing bridge; 20 - ultra-thin soft film; 30 - flow guide net; DETAILED DESCRIPTION

[0024] Before the description, it should be understood that the terms used in the specification and the appended claims should not be construed as limited to the general dictionary meanings, but interpreted in accordance with the meanings and concepts that correspond to the technical aspects of the present application based on the principle that the inventor is allowed to define the terms in order to best explain the application. Therefore, the description proposed herein is merely a preferred example for the purpose of illustrations only and is not intended to limit the scope of the application, and it should be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the application.

[0025] As Figure 1As shown, the coating plate 10 of the present invention is located on the outermost side of the ultrathin flexible film membrane assembly, and the ultrathin flexible film 20 covers the coating plate 10. Even without the use of an intermediate support layer, the ultrathin flexible film assembly can still maintain the "toughness" of the ultrathin flexible film 20 in the sewage tank and avoid adhesion due to the pulling force of water; as Figure 2 As shown, the outer frame 11 of the membrane plate 10 of the present invention can slow down the water flow speed when the aeration rises from the bottom of the sewage and the blowing water flow drives the particles to move. At the same time, it can prevent the particles from tangentially moving towards the ultra-thin flexible membrane 20, thus preventing damage to the microporous structure of the ultra-thin flexible membrane 20. This ensures that the ultra-thin flexible membrane assembly always maintains a high flux and an excellent level of effluent turbidity of less than 1 NTU. As shown in Examples 1 to 8 and Comparative Examples 1 to 4, Examples 1 to 8 all use ultra-thin flexible membranes 20 with a thickness of less than 10 μm, which can operate stably in sewage tanks and wastewater tanks, and the contact angle is much lower than that of Comparative Examples 2 and 4. The resulting permeate flow rate is 1.22-1.75 L / h and the effluent turbidity is less than 1 NTU, which is higher than the market level. As shown in Comparative Examples 1 and 3, when the ultra-thin flexible membrane 20 is simply replaced on a conventional structure, due to the thickness of the ultra-thin flexible membrane 20 being less than 10 μm, its toughness and strength are low, and it cannot operate for a long time in the particulate environment of sewage tanks and wastewater tanks, resulting in membrane rupture.

[0026] To further improve filtration performance, the ultra-thin flexible membrane 20 of the present invention can be tightly covered and fixed to the membrane plate 10, and the ultra-thin flexible membrane 20 can be controlled as follows: Figures 6-7 As shown, it is in a taut state (flat and elastic, without wrinkles), with a specific tensile strength between 10-50N, as shown in Examples 1 to 8. When the tensile strength is less than 10N, the ultrathin flexible film 20 is in a state of tension within the ultrathin flexible film assembly as shown in Examples 1 to 8. Figures 8-9 The relaxed state shown affects the permeate flow rate to below 1.50 L / h and the effluent turbidity to above 0.90 NTU. When the tensile strength is above 50 N, the micropores of the ultrathin flexible membrane 20 are overstretched, affecting the permeate flow rate to below 1.50 L / h and the effluent turbidity to above 0.90 NTU. However, when the tensile strength is controlled between 10 and 50 N, the ultrathin flexible membrane 20 has appropriate "toughness". In the sewage tank, under the conditions of ultrathinness far below that of PVDF membranes and low energy consumption with a contact angle below 80°, the ultrathin flexible membrane 20 can still maintain its filtration performance and achieve a high flux of 1.60-1.75 L / h permeate flow rate and a high filtration performance of 0.65-0.73 NTU effluent turbidity.

[0027] The ultrathin soft film 20 referred to in the present application is a polyolefin film, which can include PP film and its hydrophilic modified film, PE film and its modified film, single-layer or composite multi-layer microporous film, and the thickness of the polyolefin film can reach an ultrathin level of less than 10 um; the present application does not limit the hydrophilic modification of the PP film or the PE film, as long as a hydrophilic layer can be formed on the surface of the polyolefin film, and specific examples of the hydrophilic modification include polyvinylpyrrolidone, polyalkylene glycol, polyvinyl alcohol, polyethyleneimine, polyacrylic acid, polysulfone, etc., and the performance of the ultrathin soft film 20 in terms of water production flow rate can be improved after the hydrophilic modification due to the increased hydrophilicity of the polyolefin film.

[0028] As shown in Figure 2 , the film-coated plate 10 includes a peripheral frame 11 or a peripheral frame 11 and a reinforcing bridge 14 arranged in the area within the frame of the peripheral frame 11, and the water outlet can be arranged at any position of the assembly as long as water can be discharged; or as shown in Figure 1 , the film-coated plate 10 includes a peripheral frame 11, an inner frame 12, and a connecting bridge 13, the inner frame 12 is located in the area within the frame of the peripheral frame 11, and the peripheral frame 11 and the inner frame 12 are connected by at least one connecting bridge 13, the area within the frame of the inner frame 12 is the water outlet area, and the inner frame 12 can be arranged at the center position or any other position in the area within the frame of the peripheral frame 11, and the water outlet is more uniform and the resistance is smaller when arranged in the middle, thereby the power consumption of the water pump is relatively lower, in addition, the water outlet in the middle is better fixed, and the support effect on the ultrathin soft film 20 is the best; the cross-sectional shape of the reinforcing bridge 14 or the connecting bridge 13 can be any one of a "one" shape, a "ten" shape, a "#" shape, and a "=" shape; compared with only arranging the peripheral frame 11, the connecting bridge 13 is additionally arranged, which can effectively block the impact of particles in sewage and maintain the tension state of the ultrathin soft film 20, thereby stabilizing the water outlet performance of the film-coated plate 10.

[0029] The guide net 30 of the present application, as shown in Figures 3-4 , defines that the guide net 30 is uniformly arranged with multiple nodes, and the conventional grid is mainly a single-face flow channel structure (see Figure 5 , Figure 5 A is a side view of the contact side of the conventional grid and the thin soft film 20, Figure 5 B is a top view of the conventional grid), and the filter membrane is a single-face point contact, the guide net 30 of the present application makes the ultrathin soft film assembly contact the thin soft film 20 on both sides in a double-face point manner during the filtration process, and the water flow smoothly and quickly permeates through the ultrathin soft film 20 and forms a flow channel as shown in Figure 4 to flow to the water outlet; when the guide net as shown in Figure 3 is arranged, enough filtration contact surface is left for the two adjacent ultrathin soft films 20, and during the filtration process, the water flow can be guided as shown in Figure 4 .The flow channel shown is to maintain the water production flow rate and water turbidity of the ultra-thin film membrane assembly, as shown in Examples 1 to 8, when using single-sided point contact, the performance of water production flow rate and water turbidity is limited compared with the double-sided point contact embodiment.

[0030] The ultra-thin film 20 is symmetrically arranged on both sides of the thickness direction of the flow guide net 30 between the film-coated plate 10 and the ultra-thin film 20, and the film-coated plate 10 is arranged on the outer side of the ultra-thin film 20 away from the flow guide net 30. The present application does not limit the bonding method, which can be any method such as bonding or welding.

[0031] Example 1

[0032] A plurality of ultra-thin film membrane assemblies as shown in Figure 1 are combined in series to form a filter assembly. The thickness of the ultra-thin film 20 is 10um, the tensile strength of the ultra-thin film 20 is 10N after the ultra-thin film 20 is covered on the film-coated plate 10.

[0033] Example 2

[0034] The same as Example 1, except that the tensile strength of the ultra-thin film 20 is 50N after the ultra-thin film 20 is covered on the film-coated plate 10.

[0035] Example 3

[0036] The same as Example 1, except that the tensile strength of the ultra-thin film 20 is 25N after the ultra-thin film 20 is covered on the film-coated plate 10.

[0037] Example 4

[0038] The same as Example 1, except that the tensile strength of the ultra-thin film 20 is 20N after the ultra-thin film 20 is covered on the film-coated plate 10.

[0039] Example 5

[0040] The same as Example 1, except that the tensile strength of the ultra-thin film 20 is 30N after the ultra-thin film 20 is covered on the film-coated plate 10.

[0041] Example 6

[0042] The same as Example 1, except that the tensile strength of the ultra-thin film 20 is 5N after the ultra-thin film 20 is covered on the film-coated plate 10.

[0043] Example 7

[0044] The same as Example 1, except that the tensile strength of the ultra-thin film 20 is 60N after the ultra-thin film 20 is covered on the film-coated plate 10.

[0045] Example 8

[0046] The same as Example One, except that the flow guide net 30 is in point contact with the single-sided ultra-thin soft film 20.

[0047] Comparative Example One

[0048] The membrane module structure is connected in order of the ultra-thin soft film 20-mesh-ultra-thin soft film 20, the mesh is in single-sided point contact with the ultra-thin soft film 20, the ultra-thin soft film 20 is PE, and the film thickness is 10 um.

[0049] Comparative Example Two

[0050] The membrane module structure is connected in order of the PVDF film-mesh-PVDF film, the mesh is in single-sided point contact with the PVDF film, and the film thickness of the PVDF film is 130 um.

[0051] Comparative Example Three

[0052] The membrane module structure is connected in order of the ultra-thin soft film 20-mesh-support plate-mesh-ultra-thin soft film 20, the mesh is in single-sided point contact with the ultra-thin soft film 20, the ultra-thin soft film 20 is PE, and the film thickness is 10 um.

[0053] Comparative Example Four

[0054] The membrane module structure is connected in order of the PVDF film-mesh-support plate-mesh-PVDF film, the mesh is in single-sided point contact with the PVDF film, and the film thickness of the PVDF film is 70 um.

[0055] Test Method

[0056] SV30

[0057] The sludge settling ratio (SV30) index detection general edition procedure is as follows: the sludge settling ratio (SV30) index detection procedure of the general edition.

[0058] 1. Define SV30, i.e. sludge settling ratio. Pour the mixed aeration tank activated sludge mixture into a 1000 ml measuring cylinder to the full scale, and let it stand for 30 minutes. The volume ratio of the settled sludge to the mixed liquid is the sludge settling ratio (%), also known as the sludge settling volume (SV30), expressed in ml. Because the sludge settling reaches or approaches the maximum density after 30 minutes, this time is generally used as the standard time for determining the index.

[0059] 2. Instrument measuring cylinder, 1000 ml.

[0060] 3. Sampling and sample storage

[0061] 3.1 Sampling: The sample for monitoring SV30 should be rejected for all kinds of large fiber impurities and inorganic impurities such as large and small stones, and special attention should be paid to the representativeness of the sample.

[0062] 3.2 Sample storage: The collected water sample should be analyzed as soon as possible. The stored sample cannot be added with any protective agent to prevent the destruction of the distribution balance of the substance between solid and liquid, and should be stored in a 4℃ refrigerator, but the longest time should not exceed 12 hours.

[0063] 4. Step: Pour the mixed aeration tank activated sludge mixture into a 1000ml measuring cylinder to the full scale (VS) as soon as possible, and read the number after standing for 30 minutes. The number of milliliters read is recorded as V1.

[0064] 5. The expression of the calculation result is:

[0065]

[0066] V1 - the volume of sludge after settling (ml)

[0067] VS - the volume of mixed liquid poured into the measuring cylinder (ml)

[0068] Note: The result is retained to the first decimal place.

[0069] Tensile Strength

[0070] The tensile load borne by the test sample in the metering gage range on the unit initial cross section;

[0071] Recommended test standard: GB / T 13022-1991 or ASTM D882.

[0072] 2. Test instrument

[0073] 2.1 Tensile tester, LP5K Plus;

[0074] 2.2 Precision thickness gauge: MH-15M; 2.3 cutting knife; 2.4 steel ruler.

[0075] 3. Test preparation

[0076] 3.1 Sample shape and size

[0077] The sample used in this method is a long strip with a width of 10-25mm and a total length of not less than 150mm;

[0078] 3.2 Sample preparation and quantity

[0079] The long strip sample is cut with a cutting knife, and the sample edge is smooth without notches. The notches are checked using a low-power magnifying glass, and the sample with edge defects is discarded. The marking line should be accurately printed or drawn according to the sample size requirements, and this marking line should not have any effect on the sample.

[0080] Number of test specimens: The test is carried out in one group for each test direction, and the number of test specimens in each group is not less than 5.

[0081] 3.3 Test specimen cutting method

[0082] The test specimen shall be cut from the MD and TD directions respectively, and the cutting method is shown in Figure 12 .

[0083] 4. Test conditions

[0084] 4.1 The state adjustment is carried out according to the standard environment normal deviation range specified in GB 2918, the time is not less than 4 h, and the test is carried out in this environment.

[0085] 4.2 Test speed: 250 ± 25 mm / min.

[0086] 5. Test procedure

[0087] 5.1 The thickness of the test specimen is measured by a thickness gauge, and the width of the test specimen is measured by a steel ruler. The thickness and width of each test specimen shall be measured at three points within the gauge length, and the arithmetic mean value is taken;

[0088] 5.2 The test specimen is placed in the two clamps of the testing machine, the longitudinal axis of the test specimen is coincided with the center line of the upper and lower clamps, and the tightness is appropriate to prevent the test specimen from slipping and breaking in the clamp, and the clamp shall be lined with elastic materials such as rubber;

[0089] 5.3 The testing machine is started to carry out the test at the specified speed;

[0090] 5.4 After the test specimen is broken, the tensile curve and related stress and strain values are recorded, if the test specimen is broken at a position outside the gauge line, this test specimen is discarded and another test specimen is used to redo the test.

[0091] 6. Calculation and representation of results

[0092] 6.1 The tensile strength is represented by σt (MPa), and is calculated according to formula (1):

[0093]

[0094] In the formula: p - maximum load, breaking load, yield load, N;

[0095] b - width of test specimen, mm;

[0096] d - thickness of test specimen, mm.

[0097] 6.2 If the standard deviation value S is required to be calculated, it is calculated according to formula (3);

[0098]

[0099] X - single measured value;

[0100] X - average value of a set of measured values;

[0101] n - number of measured values.

[0102] 7. Notes

[0103] 7.1 When cutting the sample, pay attention to whether the sample edge meets the requirements of smoothness and no gap;

[0104] 7.2 When stretching, pay attention to the change of the sample position.

[0105] Water Production Flow

[0106] The water production flow rate is measured by a self-priming pump, a pipeline system equipped with a pressure gauge, etc. The stable pressure is 0.2 bar, the running time is 5 min, and then it is converted into L / ㎡·h.

[0107] Contact Angle

[0108] The contact angle is measured by a contact angle measuring instrument. Turn on the computer, turn on the power switch of the optical contact angle measuring instrument, open the software on the computer desktop, turn on the camera, and adjust the camera light brightness. Place the sample to be tested on the lifting platform, adjust the height of the test platform, so that the hydrophobic coating surface of the sample to be tested can be observed on the computer side. Set the drop size to 3-5uL on the computer side, click the drop button with the mouse, and make the droplet drop on the sample surface. Adjust the position of the baseline at the junction of the droplet and the sample with the mouse double-click left button or the up and down keys on the computer keyboard, and adjust the size of the frame so that the entire droplet is within the frame line without any impurities. Press the Enter key on the keyboard to get the test results and record the data. The detailed test results are displayed on the lower right corner of the computer screen, showing the maximum angle, minimum angle, and average angle. Drag the mouse to the upper left corner of the screen, select Save As, select the save path, and save the test results. After the test is completed, adjust the height of the lifting platform to the lowest end, turn off the program on the computer side, turn off the camera light, turn off the power switch of the optical contact angle measuring instrument, and shut down the computer.

[0109] The contact angle is the angle between the solid-liquid interface and the gas-liquid interface. The contact angle reflects the surface tension, and the smaller the contact angle value, the smaller the surface tension. On the ultra-thin film, the better the hydrophilicity, the smaller the power consumption.

[0110] Turbidity of Water Production

[0111] The Hach 2100N laboratory turbidimeter is used for turbidity measurement from 0 to 4000 NTU (scattered turbidity units). The instrument features automatic range switching and decimal point positioning. Measurements of high-turbidity samples are performed by diluting the original sample solution with filtered sample and then performing simple calculations.

[0112] 1. Collect a representative sample in a clean container, then pour the sample from the container into the sample tube up to the graduation mark (about 30 mL), carefully hold the top of the sample tube, and screw on the sample tube cap.

[0113] Note: Instrument warm-up and stabilization time: 30 minutes in Ratio mode, 60 minutes in non-Ratio mode.

[0114] 2. Hold the sample tube cap and wipe away any water droplets or fingerprints from the outside of the tube.

[0115] 3. Apply a thin layer of silicone oil to the outer wall of the pipe from top to bottom, and then wipe it evenly with an oil-wiping cloth until the oil film is almost invisible.

[0116] 4. Insert the sample tube into the turbidimeter's tube holder and close the holder cover.

[0117] Note: Press ENTER to update the digital display reading immediately.

[0118] 5. Press the RANGE key to select manual or automatic range mode (generally, select automatic range mode, i.e., the AUTO signal will light up).

[0119] 6. Press the SIGNAC AVG button to select the appropriate signal averaging setting (the SIGNAC AVG indicator light will illuminate).

[0120] 7. Press the RA710 key to select the ratio setting (the Ratio indicator light will illuminate).

[0121] Note: When using 740NTU, the Ratio setting must be used.

[0122] 8. Press the UNITS Exit key and select the unit of measurement (NTU EBC or NEPH).

[0123] 9. Read and record the measurement results.

[0124] The filter components assembled from Examples 1 to 8 and Comparative Examples 1 to 4 were placed in a chemical wastewater tank and a sewage tank, respectively, and operated for 8 minutes at an inlet pressure of 20 kPa and a water temperature of 30°C using a self-priming pump. Specific filtration data are as follows: Figures 10-11 As shown.

[0125] like Figures 10-11As shown, the film-coated plate 10-ultra-thin film 20-flow guide net 30-ultra-thin film 20-film-coated plate 10 structure of the present application can be applied to the sewage pool and waste water pool with SV30 of 70 or 65, and when the thickness, tensile strength of the ultra-thin film 20 and the structure of the flow guide net 30 are limited at the same time, the ultra-thin film 20 is in contact with no wrinkles, the filtration flow resistance is relatively smaller in this form, the water production channel is smooth, and a filtration assembly with water production flow of 1.72-1.75 L / h and water turbidity of 0.65 NTU can be obtained, which can meet the market water purification demand under low energy consumption.

[0126] The above is only the preferred embodiment of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the concept of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. An ultrathin flexible film assembly, characterized in that, Including: A coated plate (10), an ultra-thin soft film (20), and a flow guiding net (30). Ultra-thin soft films (20) are symmetrically arranged on both sides in the thickness direction of the flow guiding net (30). Coated plates (10) are arranged on the outer sides of the ultra-thin soft films (20) away from the flow guiding net (30). Among them, the flow guiding net (30) is in node contact with the ultra-thin soft films (20) on both sides. The film thickness of the ultra-thin soft film (20) is below 10 um, and the tensile strength of the ultra-thin soft film (20) is between 10 - 50 N.

2. The ultrathin flexible film assembly as described in claim 1, characterized in that, The coated plate (10) includes an outer frame (11) or an outer frame (11) and a reinforcing bridge (14) arranged in the area inside the outer frame (11).

3. The ultrathin flexible film assembly as described in claim 1, characterized in that, The coated plate (10) includes an outer frame (11), an inner frame (12), and a connecting bridge (13). The inner frame (12) is located in the area inside the outer frame (11), and the outer frame (11) is connected to the inner frame (12) through at least one connecting bridge (13).

4. The ultrathin flexible film assembly as described in claim 1, characterized in that, The ultra-thin soft film (20) is a polyolefin film.

5. The ultrathin flexible film assembly as described in claim 4, characterized in that, The ultra-thin soft film (20) is a single-layer film or a composite multi-layer film of a PP film, a PE film, a hydrophilic modified PP film, or a hydrophilic modified PE film.

6. The ultrathin flexible film assembly as described in claim 3, characterized in that, The cross-sectional shape of the connecting bridge (13) is any one of a "one" shape, a "ten" shape, a "#" shape, and an "=" shape.

7. The ultrathin flexible film assembly as described in claim 2, characterized in that, The cross-sectional shape of the reinforcing bridge (14) is any one of a "one" shape, a "ten" shape, a "#" shape, and an "=" shape.

8. The ultrathin flexible film assembly as described in claim 1, characterized in that, The coated plate (10), the ultra-thin soft film (20), and the flow guiding net (30) are adhesively bonded or welded to each other in sequence.

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