Water treatment membrane

Abstract

The utility model provides a water treatment membrane. The water treatment membrane comprises a non-woven fabric supporting layer, a bonding layer, a polyolefin porous layer, a compact skin layer and a protective skin layer which are sequentially stacked, wherein the bonding layer is partially embedded into partial pore structures of the non-woven fabric supporting layer and the polyolefin porous layer to form an interlayer overlapping region; and the compact skin layer is partially embedded into a part of pore structure of the polyolefin porous layer to form an interlayer overlapping region. The water treatment membrane provided by the utility model has good solvent resistance and pressure resistance, and can improve the problems of flow channel blockage and flux reduction caused by deformation of a high-pressure structure.

Description

Technical Field

[0001] The utility model belongs to the technical field of membranes and relates to a water treatment membrane. Background Art

[0002] Traditional water treatment membranes are generally prepared by coating a polysulfone layer on a non-woven fabric substrate as a support layer. Due to problems with the non-woven fabric and polysulfone materials, traditional water treatment membranes have poor solvent resistance.

[0003] In recent years, water treatment membranes have been developed that use a polyolefin porous membrane as a substrate and a polyamide layer formed on its surface through interfacial polymerization to improve its solvent resistance. However, polyolefin porous membranes are generally not pressure-resistant and their structure easily deforms under high pressure, leading to blockage of the membrane's flow channels and reduced flux.

[0004] Therefore, in the art, it is desired to develop a water treatment membrane that has both good solvent resistance and good pressure resistance. Utility Model Content

[0005] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a water treatment membrane with good solvent resistance and pressure resistance, which can improve the problems of flow channel blockage and flux reduction caused by high-pressure structural deformation.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] The utility model provides a water treatment membrane, which comprises a non-woven fabric support layer, an adhesive layer, a polyolefin porous layer, a dense skin layer and a protective skin layer which are stacked in sequence;

[0008] The adhesive layer is partially embedded in the non-woven fabric support layer and the partial pore structure of the polyolefin porous layer to form an interlayer overlapping area; the dense skin layer is partially embedded in the partial pore structure of the polyolefin porous layer to form an interlayer overlapping area.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] The water treatment membrane provided by the utility model composites a non-woven fabric support layer with a polyolefin porous layer, which can enhance the compressive strength of the polyolefin porous layer; the adhesive layer is partially embedded in the non-woven fabric support layer and the polyolefin porous layer, which can achieve good connectivity between the layers and ensure that no interlayer slip occurs between the non-woven fabric support layer and the polyolefin porous layer, further avoiding structural deformation of the water treatment membrane in a high-pressure water application environment; the dense skin layer is partially embedded in the polyolefin porous layer to form a good combination with the polyolefin porous layer, further improving the efficient separation effect and high-pressure resistance of the water treatment membrane; the protective skin layer is arranged on the side of the dense skin layer away from the polyolefin porous layer, which can increase the service life of the water treatment membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic structural diagram of the water treatment membrane provided in Example 1;

[0012] Among them, 1- non-woven fabric support layer, 2- adhesive layer, 3- polyolefin porous layer, 4- dense skin layer, 5- protective skin layer, 6- overlapping area between dense skin layer and polyolefin porous layer.

[0013] Figure 2 This is a schematic diagram showing the reversible deformation of the water treatment membrane provided by an embodiment of the present invention after being subjected to high water pressure. DETAILED DESCRIPTION

[0014] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention is further described in detail below.

[0015] As mentioned above, conventional reverse osmosis membranes can be used as water treatment membranes. They are generally prepared by coating a polysulfone layer on a non-woven fabric substrate as a support layer. Due to problems with the non-woven fabric and polysulfone materials, conventional reverse osmosis membranes have poor solvent resistance. In recent years, reverse osmosis membranes have been developed that use polyolefin porous membranes as a substrate and form a polyamide layer through interfacial polymerization on their surface to improve the solvent resistance of reverse osmosis membranes. However, polyolefin porous membranes are generally not pressure-resistant and their structure is easily deformed under high-pressure conditions, resulting in blockage of the flow channel of the reverse osmosis membrane and a decrease in flux.

[0016] Therefore, it is urgent to develop a water treatment membrane that is both solvent-resistant and pressure-resistant.

[0017] The utility model provides a water treatment membrane, which comprises a non-woven fabric support layer, an adhesive layer, a polyolefin porous layer, a dense skin layer and a protective skin layer which are stacked in sequence;

[0018] The adhesive layer is partially embedded in the non-woven fabric support layer and the partial pore structure of the polyolefin porous layer to form an interlayer overlapping area; the dense skin layer is partially embedded in the partial pore structure of the polyolefin porous layer to form an interlayer overlapping area.

[0019] The water treatment membrane provided by the utility model composites a non-woven fabric support layer with a polyolefin porous layer, which can enhance the compressive strength of the polyolefin porous layer; the adhesive layer is partially embedded in the non-woven fabric support layer and the polyolefin porous layer, which can achieve good connectivity between the layers and ensure that no interlayer slip occurs between the non-woven fabric support layer and the polyolefin porous layer, further avoiding structural deformation of the water treatment membrane in a high-pressure water application environment; the dense skin layer is partially embedded in the polyolefin porous layer to form a good combination with the polyolefin porous layer, further improving the efficient separation effect and high-pressure resistance of the water treatment membrane; the protective skin layer is arranged on the side of the dense skin layer away from the polyolefin porous layer, which can increase the service life of the water treatment membrane.

[0020] In some embodiments, the adhesive layer is discontinuously distributed between the non-woven fabric support layer and the polyolefin porous layer in an island-in-sea structure, thereby ensuring that the non-woven fabric support layer and the polyolefin porous layer will not cause a decrease in flux performance due to blockage of the interface flow channel after the adhesive layer is composited.

[0021] In some embodiments, based on the total area of ​​the side of the non-woven fabric support layer in contact with the adhesive layer as 100%, the area of ​​the adhesive layer accounts for 0.5%-30%, for example, it can be 0.5%, 1%, 3%, 5%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30% or any two thereof.

[0022] In some embodiments, the overlapping thickness of the adhesive layer and the non-woven support layer accounts for 0.3%-1% of the overall thickness of the non-woven support layer, for example, it can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1% or any two thereof.

[0023] In some embodiments, the overlapping thickness of the adhesive layer and the polyolefin porous layer accounts for 1%-6% of the overall thickness of the polyolefin porous layer, for example, it can be 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5%, 5.2%, 5.4%, 5.6%, 5.8%, 6% or any two thereof.

[0024] In some embodiments, the spacing between the non-woven fabric support layer and the polyolefin porous layer (i.e., the thickness of the portion of the adhesive layer not embedded in the non-woven fabric support layer and the polyolefin porous layer) is 60-300 nm, for example, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, or any two thereof. This further ensures the continuity of the flow channel and the flux performance of the water treatment membrane.

[0025] In some embodiments, the adhesive layer is a polyethylene wax layer. The polyethylene wax can be melted into the pores of the non-woven fabric support layer and the polyolefin porous layer by hot pressing to connect the non-woven fabric support layer and the polyolefin porous layer.

[0026] In some embodiments, the non-woven fabric support layer is any one of a polyolefin fiber layer, a polyethylene terephthalate (PET) fiber layer, a polyamide fiber layer, a polyimide fiber layer, a polytetrafluoroethylene layer, a polyphenylene sulfide fiber layer, a polyacrylonitrile fiber layer, and an aramid fiber layer.

[0027] In some embodiments, the thickness of the nonwoven support layer is 20-80 μm, for example, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm or any two thereof, more preferably 45-65 μm.

[0028] In some embodiments, the polyolefin porous layer is any one of a polypropylene porous membrane layer, a polyethylene porous membrane layer, a polybutylene porous membrane layer, and a polypentene porous membrane layer.

[0029] The thickness, porosity, air permeability, and tensile strength of the olefin porous membrane of the present invention are not particularly limited, and existing polyolefin porous membranes can be directly used. However, based on considerations of better flux and deformation resistance of the water treatment membrane, in some embodiments, the thickness of the polyolefin porous layer is 10-32 μm, for example, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, 32 μm, or a range consisting of any two thereof.

[0030] In some embodiments, the pore size of the polyolefin porous layer is 13-43 nm, for example, 13 nm, 15 nm, 18 nm, 20 nm, 23 nm, 25 nm, 28 nm, 30 nm, 33 nm, 35 nm, 38 nm, 40 nm, 43 nm or a range consisting of any two thereof, and the porosity is 40%-60%, for example, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60% or a range consisting of any two thereof.

[0031] In some embodiments, the polyolefin porous layer has an air permeability of 25-350 s / 100 mL, for example, 25 s / 100 mL, 50 s / 100 mL, 80 s / 100 mL, 100 s / 100 mL, 150 s / 100 mL, 200 s / 100 mL, 250 s / 100 mL, 300 s / 100 mL, 330 s / 100 mL, 350 s / 100 mL or any two thereof.

[0032] In some embodiments, the tensile strength of the polyolefin porous layer is 600 kgf / cm 2Above, for example 620kgf / cm 2 、630kgf / cm 2 、650kgf / cm 2 、680kgf / cm 2 Or a range consisting of any two of them. This optimizes the performance of the water treatment membrane, making it have a large water flux, good mechanical properties, and high deformation resistance.

[0033] In some embodiments, the dense cortex is a polyamide cortex, a polyurethane cortex, or a polyester cortex. The dense cortex can be formed on the surface of the polyolefin porous layer through an interfacial reaction; the polymer in the dense cortex forms fibrils to form a three-dimensional network structure, and the dense cortex can achieve high-efficiency reverse osmosis separation.

[0034] In some embodiments, the overall thickness of the dense cortex is 20-500 nm, for example, 20 nm, 30 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm or any two thereof, more preferably 50-250 nm.

[0035] In some embodiments, the overlapping thickness of the dense skin layer and the polyolefin porous layer accounts for 0.1%-2% of the overall thickness of the polyolefin porous layer, for example, it can be 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2% or any two thereof.

[0036] In some embodiments, the protective skin layer is a polyvinyl alcohol layer or a poly (N-methylpyrrolidone) layer. The protective skin layer can be applied to the side of the dense skin layer away from the polyolefin porous layer by spraying, roller printing, etc., to improve the pollution resistance and service life of the water treatment membrane.

[0037] In some embodiments, the thickness of the protective skin layer is 0.05-1 μm, for example, it can be 0.05 μm, 0.06 μm, 0.08 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm or any two thereof.

[0038] It should be noted that the cross-sectional structure of the water treatment membrane can be characterized by scanning electron microscopy to measure the overlapping thickness between the adhesive layer and the non-woven fabric support layer and the polyolefin porous layer, and the overlapping thickness between the dense skin layer and the polyolefin porous layer.

[0039] The present invention has no particular restrictions on the preparation method of the water treatment membrane. For example, the following method can be used:

[0040] (1) coating the adhesive layer material on one side surface of the non-woven fabric support layer, then compounding the polyolefin porous layer, and hot pressing to obtain a three-layer composite structure of the non-woven fabric support layer-adhesive layer-polyolefin porous layer;

[0041] Alternatively, the adhesive layer material is coated on one side of the polyolefin porous layer, and then the non-woven fabric support layer is composited and hot-pressed to obtain a three-layer composite structure of non-woven fabric support layer-adhesive layer-polyolefin porous layer;

[0042] (2) performing interfacial polymerization on the surface of the polyolefin porous layer away from the adhesive layer to form a dense skin layer, coating the surface of the dense skin layer with a material for protecting the skin layer, and drying to obtain the water treatment membrane.

[0043] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. Those skilled in the art should understand that the specific embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0044] Example 1

[0045] In this embodiment, a water treatment membrane is provided, and its structural schematic diagram is shown as follows: Figure 1 As shown, the water treatment membrane comprises a non-woven fabric support layer 1, an adhesive layer 2, a polyolefin porous layer 3, a dense skin layer 4 and a protective skin layer 5 which are stacked in sequence;

[0046] Among them, the adhesive layer is a polyethylene wax layer, which is discontinuously distributed between the non-woven fabric support layer and the polyolefin porous layer in an island structure. The total area of ​​the side of the non-woven fabric support layer in contact with the adhesive layer is 100%, and the area of ​​the adhesive layer accounts for 8%; the adhesive layer is partially embedded in the partial pore structure of the non-woven fabric support layer and the polyolefin porous layer to form an interlayer overlapping area. The overlapping thickness of the adhesive layer and the non-woven fabric support layer accounts for 0.6% of the total thickness of the non-woven fabric support layer, and the overlapping thickness of the adhesive layer and the polyolefin porous layer accounts for 2% of the total thickness of the polyolefin porous layer. The spacing between the non-woven fabric support layer and the polyolefin porous layer is 100 nm.

[0047] The non-woven fabric support layer is polypropylene non-woven fabric with a thickness of 50 μm;

[0048] The polyolefin porous layer is a polyethylene porous membrane layer with a thickness of 20 μm, a pore size of 38 nm, a porosity of 48%, an air permeability of 180 s / 100 mL, and a tensile strength of 1200 kgf / cm 2 ;

[0049] The dense skin layer is a polyamide skin layer with a total thickness of 100 nm. The dense skin layer is partially embedded in the pore structure of the polyolefin porous layer to form an interlayer overlapping region 6. The overlapping thickness of the dense skin layer and the polyolefin porous layer accounts for 0.2% of the total thickness of the polyolefin porous layer.

[0050] The protective layer is a polyvinyl alcohol layer with a thickness of 0.3 μm.

[0051] The preparation method of the water treatment membrane comprises the following steps:

[0052] (1) coating polyethylene wax on one surface of a non-woven fabric support layer, then compounding a polyolefin porous layer, and hot pressing to obtain a three-layer composite structure of a non-woven fabric support layer-adhesive layer-polyolefin porous layer;

[0053] (2) interfacial polymerization is performed on the surface of the polyolefin porous layer away from the adhesive layer to form a dense cortex, and a material for protecting the cortex is coated on the surface of the dense cortex (specifically: the composite membrane obtained in step (1) is infiltrated with an aqueous solution of m-phenylenediamine, and then a n-hexane solution of trimesoyl chloride is coated on the interface, and the mixture is reacted for a period of time to form a dense cortex; polyvinyl alcohol PVA0588 is coated on the surface of the dense cortex as a material for protecting the cortex), and dried to obtain the water treatment membrane.

[0054] Example 2

[0055] The only difference between this embodiment and embodiment 1 is that, based on the total area of ​​the side of the non-woven fabric support layer in contact with the adhesive layer being 100%, the area of ​​the adhesive layer accounts for 0.5%.

[0056] Example 3

[0057] The only difference between this embodiment and embodiment 1 is that, based on the total area of ​​the side of the non-woven fabric support layer in contact with the adhesive layer being 100%, the area of ​​the adhesive layer accounts for 30%.

[0058] Example 4

[0059] The only difference between this embodiment and embodiment 1 is that the overlapping thickness of the adhesive layer and the non-woven fabric support layer accounts for 0.3% of the entire thickness of the non-woven fabric support layer, and the non-woven fabric support layer is PET non-woven fabric.

[0060] Example 5

[0061] The only difference between this embodiment and embodiment 1 is that the overlapping thickness of the adhesive layer and the non-woven fabric support layer accounts for 1% of the total thickness of the non-woven fabric support layer.

[0062] Example 6

[0063] The only difference between this embodiment and embodiment 1 is that the overlapping thickness of the adhesive layer and the polyolefin porous layer accounts for 6% of the total thickness of the polyolefin porous layer.

[0064] Example 7

[0065] The only difference between this embodiment and embodiment 1 is that the distance between the non-woven fabric support layer and the polyolefin porous layer is 300 nm.

[0066] Example 8

[0067] The only difference between this embodiment and embodiment 1 is that the thickness of the protective skin layer is 0.05 μm.

[0068] Example 9

[0069] The only difference between this embodiment and embodiment 1 is that the thickness of the protective skin layer is 1 μm.

[0070] Example 10

[0071] The only difference between this embodiment and embodiment 1 is that the overlapping thickness of the dense skin layer and the polyolefin porous layer accounts for 2% of the total thickness of the polyolefin porous layer.

[0072] Example 11

[0073] The only difference between this embodiment and embodiment 1 is that, based on the total area of ​​the side of the non-woven fabric support layer in contact with the adhesive layer being 100%, the area of ​​the adhesive layer accounts for 40%.

[0074] Comparative Example 1

[0075] The only difference between this comparative example and Example 1 is that the water treatment membrane does not include an adhesive layer. Specifically, the non-woven fabric support layer and the polyolefin porous layer are composited by hot pressing at 100° C. for 3 seconds.

[0076] The performance test of the water treatment membrane provided in the embodiment and the comparative example was carried out, and the test method was as follows:

[0077] (1) Water flux and desalination performance: Referring to the household reverse osmosis membrane test conditions in the standard GBT32373-2015 reverse osmosis membrane test method, the water flux and desalination rate of 5 tons of water were used as the characterization.

[0078] (2) Pressure resistance: Refer to the test conditions of seawater desalination reverse osmosis membrane in the standard GBT32373-2015 reverse osmosis membrane test method, and the pressure resistance of running 5 tons of water is used as the characterization.

[0079] (3) Solvent resistance: Refer to the standard GBT32373-2015 reverse osmosis membrane test method, except that the test medium is replaced by a mixed medium of DMF / water (mass ratio 3 / 7) for testing, and the desalination performance is characterized by the percentage decrease after running 5 tons of water.

[0080] The performance test results are shown in Table 1.

[0081] Table 1

[0082]

[0083] As can be seen from Table 1, the water treatment membranes provided by the embodiments of the present invention have good solvent resistance and good pressure resistance, and can improve the flow channel blockage and flux reduction problems caused by high-pressure structural deformation. The water treatment membranes provided by the embodiments of the present invention are reversible after being subjected to high water pressure, as shown in the schematic diagram. Figure 2 As shown, the water treatment membrane only shows a three-layer composite structure of a non-woven fabric support layer-an adhesive layer-a polyolefin porous layer.

[0084] Compared with Example 1, the pressure resistance and solvent resistance of the water treatment membrane provided in Comparative Example 1 are significantly reduced.

[0085] The applicant declares that the above is only a specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Technicians in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technicians in the relevant technical field within the technical scope disclosed in the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A water treatment membrane, characterized in that The water treatment membrane comprises a non-woven fabric support layer, an adhesive layer, a polyolefin porous layer, a dense skin layer and a protective skin layer which are stacked in sequence; The adhesive layer is partially embedded in the non-woven fabric support layer and the partial pore structure of the polyolefin porous layer to form an interlayer overlapping area; the dense skin layer is partially embedded in the partial pore structure of the polyolefin porous layer to form an interlayer overlapping area.

2. The water treatment membrane according to claim 1, characterized in that The adhesive layer is discontinuously distributed between the non-woven fabric support layer and the polyolefin porous layer in an island-in-sea structure; Taking the total area of ​​the side of the non-woven fabric support layer in contact with the adhesive layer as 100%, the area of ​​the adhesive layer accounts for 0.5%-30%.

3. The water treatment membrane according to claim 1, characterized in that The overlapping thickness of the adhesive layer and the non-woven fabric support layer accounts for 0.3% to 1% of the entire thickness of the non-woven fabric support layer.

4. The water treatment membrane according to claim 1, characterized in that The overlapping thickness of the adhesive layer and the polyolefin porous layer accounts for 1% to 6% of the entire thickness of the polyolefin porous layer.

5. The water treatment membrane according to claim 1, characterized in that The distance between the non-woven fabric support layer and the polyolefin porous layer is 60-300 nm.

6. The water treatment membrane according to claim 1, characterized in that The adhesive layer is a polyethylene wax layer.

7. The water treatment membrane according to claim 1, characterized in that The thickness of the non-woven fabric support layer is 20-80 μm.

8. The water treatment membrane according to claim 1, characterized in that The thickness of the polyolefin porous layer is 10-32 μm, the pore diameter is 13-43 nm, and the porosity is 40%-60%.

9. The water treatment membrane according to claim 1, characterized in that The overall thickness of the dense cortex is 20-500 nm; The overlapping thickness of the dense skin layer and the polyolefin porous layer accounts for 0.1% to 2% of the entire thickness of the polyolefin porous layer.

10. The water treatment membrane according to claim 1, characterized in that The thickness of the protective skin layer is 0.05-1 μm.

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