Hollow fiber membrane free end packaging method and hollow fiber membrane bundle

Abstract

The present invention provides a method for packaging the free end of a hollow fiber membrane and a hollow fiber membrane bundle, and specifically relates to the field of water treatment technology. The method for packaging the free end of the hollow fiber membrane comprises the following steps: A. After sealing the free end of the hollow fiber membrane bundle, immersing it in an aqueous silicone oil solution, taking it out and drying it, and then cutting the head once to expose the inner hole of the hollow fiber membrane; B. Inserting the free end after the head is cut once into packaging glue for curing, and then taking out the free end to obtain the packaged free end. The packaging method provided by the present invention makes the burst strength of the free end packaging structure stably exceed 0.4MPa, meeting the long-term stable operation requirements under high pressure conditions. The packaging method is simple and easy to implement, reduces the amount of glue used, does not require precision cutting equipment, shortens the process, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, in particular to a packaging method for the free end of a hollow fiber membrane and a hollow fiber membrane bundle. Background Art

[0002] Traditional hollow fiber membrane modules use a rigid fixed structure at both ends. The distance between membrane fibers cannot be dynamically adjusted during operation, which causes pollutants to easily accumulate in the gaps between the membrane fibers and form a bridging effect. This not only causes a significant decrease in membrane flux (the flux attenuation can reach 40%-60% after 100 hours), but also increases the risk of membrane fiber breakage.

[0003] To solve this problem, free-end hollow fiber membrane modules came into being. By keeping one end of the membrane filament free and using the fluid shear force to make the membrane filament swing to destroy the pollutant deposition layer, the pollution rate can be reduced by 30%-50%. However, this puts higher requirements on the packaging process.

[0004] While some existing packaging processes achieve reliable sealing, they are limited to processing only 2-9 membrane filaments per batch due to process limitations. Even with expensive automated equipment, production costs remain high. Other packaging processes, while suitable for large-scale production, are complex and time-consuming, require large amounts of glue, and require stringent cutting precision (error must be less than 0.1mm).

[0005] The current free-end membrane module packaging technology still faces multiple challenges of low production efficiency, complex process and high cost. It is urgent to develop new high-efficiency and low-cost large-scale packaging processes to meet market demand.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] One of the objectives of the present invention is to provide a method for packaging the free end of a hollow fiber membrane, aiming to solve at least one of the above-mentioned technical problems in the prior art.

[0008] A second object of the present invention is to provide a hollow fiber membrane bundle.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0010] A first aspect of the present invention provides a method for encapsulating the free end of a hollow fiber membrane, comprising the following steps:

[0011] A. Cap the free end of the hollow fiber membrane bundle and immerse it in an aqueous silicone oil solution. After drying, cut the end to expose the inner pores of the hollow fiber membrane.

[0012] B. Insert the free end after the first cut into packaging glue and solidify it, then remove the free end to obtain the encapsulated free end.

[0013] Furthermore, in step A, after being immersed in the aqueous silicone oil solution, the aqueous silicone oil layer formed at the free end has a first height after the head is cut once.

[0014] In step B, the insertion depth into the packaging glue is a first depth.

[0015] Furthermore, the first height is greater than the first depth.

[0016] Furthermore, the first height is greater than the first depth by more than 1 cm.

[0017] Furthermore, the first depth is 5-20 mm.

[0018] Furthermore, the mass concentration of the aqueous silicone oil solution is 5-20%.

[0019] And / or, the aqueous silicone oil includes at least one of polyether-modified silicone oil, amino-modified silicone oil, carboxyl-modified silicone oil and hydroxyl-modified silicone oil.

[0020] Furthermore, the packaging glue includes at least one of epoxy resin glue, polyurethane glue, phenolic resin glue, polyisocyanate glue, polyvinyl acetate glue, polyethylene-vinyl acetate glue, acrylate glue, polystyrene glue, alkyd resin glue, and cellulose glue.

[0021] A second aspect of the present invention provides a hollow fiber membrane bundle, which is composed of a plurality of hollow fiber membrane filaments;

[0022] The hollow fiber membrane comprises a sealed end and an open end at both ends of the membrane;

[0023] The sealing end is sealed using the packaging method described in the first aspect.

[0024] Furthermore, the diameter of the hollow fiber membrane is 0.2~5mm.

[0025] Furthermore, the material of the hollow fiber membrane includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethersulfone, polysulfone, polypropylene, polyethylene, polyvinyl chloride, polyacrylonitrile and polyisoprene.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] The encapsulation method provided by the present invention forms a soluble temporary isolation layer by immersing the free end of the membrane bundle in an aqueous silicone oil solution, which can effectively block the direct adhesion between the encapsulation glue and the surface of the membrane filament. After curing, the membrane filament can be completely extracted from the glue plug to ensure that there is no colloid adhesion between the hollow fiber membranes, and at the same time realize the dynamic swing function of the free end. The aqueous silicone oil has the characteristics of water solubility and can be completely removed by subsequent water washing, avoiding the blockage of the membrane pores or performance degradation caused by the residue of traditional release agents. In addition, the axial size of the sealing plug after curing can be directly determined by controlling the immersion depth of the membrane bundle into the encapsulation glue, simplifying the process while realizing the directional regulation of the sealing strength. This method makes the burst strength of the free end encapsulation structure stably exceed 0.4MPa, meeting the long-term stable operation requirements under high pressure conditions. The encapsulation method is simple and easy to implement, reduces the amount of glue used, does not require precision cutting equipment, shortens the process, and is suitable for large-scale industrial production.

[0028] The hollow fiber membrane bundle provided by the present invention, in view of the advantages of the above-mentioned packaging method, reduces the preparation cost of the prepared hollow fiber membrane bundle, reduces the use cost of downstream industries, and promotes the development of downstream industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 Schematic diagram of the packaging method for the free end of the hollow fiber membrane provided by the present invention.

[0031] Icon: 1-Hollow fiber membrane; 2-Water-based silicone oil coating; 3-Encapsulation glue. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0033] Hereinafter, the terms "including", "having" and their cognates, which may be used in various embodiments of the present invention, are intended only to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0034] A first aspect of the present invention provides a method for encapsulating the free end of a hollow fiber membrane, comprising the following steps:

[0035] A. Cap the free end of the hollow fiber membrane bundle and immerse it in an aqueous silicone oil solution. After drying, cut the end to expose the inner pores of the hollow fiber membrane.

[0036] B. Insert the free end after the first cut into packaging glue and solidify it, then remove the free end to obtain the encapsulated free end.

[0037] The encapsulation method provided by the present invention forms a soluble temporary isolation layer by immersing the free end of the membrane bundle in an aqueous silicone oil solution, which can effectively block the direct adhesion between the encapsulation glue and the surface of the membrane filament. After curing, the membrane filament can be completely extracted from the glue plug to ensure that there is no colloid adhesion between the hollow fiber membranes, and at the same time realize the dynamic swing function of the free end. The aqueous silicone oil has the characteristics of water solubility and can be completely removed by subsequent water washing, avoiding the blockage of the membrane pores or performance degradation caused by the residue of traditional release agents. In addition, the axial size of the sealing plug after curing can be directly determined by controlling the immersion depth of the membrane bundle into the encapsulation glue, simplifying the process while realizing the directional regulation of the sealing strength. This method makes the burst strength of the free end encapsulation structure stably exceed 0.4MPa, meeting the long-term stable operation requirements under high pressure conditions. The encapsulation method is simple and easy to implement, reduces the amount of glue used, does not require precision cutting equipment, shortens the process, and is suitable for large-scale industrial production.

[0038] Before impregnation, check the free ends of the hollow fiber membrane bundle for alignment. If the free ends are misaligned, they should be trimmed to ensure uniform impregnation depth. Furthermore, if the free ends need to be fixed later, trimming should be completed before fixing to ensure a good fixation effect.

[0039] In some embodiments of the present invention, quick-drying adhesive is used to seal the free ends of the hollow fiber membrane bundle to facilitate the subsequent impregnation process. This pre-sealing ensures a uniform immersion depth throughout the hollow fiber membrane bundle and prevents aqueous silicone oil from entering the membrane pores.

[0040] Furthermore, in step A, after being immersed in the aqueous silicone oil solution, the aqueous silicone oil layer formed at the free end has a first height after the head is cut once.

[0041] The single-stage head cutting is achieved by removing the quick-drying glue sealing layer at the end of the membrane bundle after impregnation with water-based silicone oil, accurately exposing the inner pores of the hollow fiber membrane. This not only ensures the integrity of the fluid channel, but also forms a flat end face reference to improve the positioning accuracy of subsequent glue packaging.

[0042] In step B, the insertion depth into the packaging glue is a first depth.

[0043] Furthermore, the first height is greater than the first depth.

[0044] like Figure 1 As shown in the schematic diagram of the hollow fiber membrane free end encapsulation method provided by the present invention, a water-based silicone oil coating 2 having a specific first height is formed on the free end surface of the hollow fiber membrane filament 1. During the encapsulation process, the free end with the water-based silicone oil coating 2 is immersed in encapsulation glue 3 to a first depth. Process control is used to ensure that the first height is greater than the first depth to achieve a reliable encapsulation effect.

[0045] Furthermore, the first height is at least 1 cm greater than the first depth. To ensure encapsulation quality, the immersion depth of the encapsulating glue (i.e., the first depth) should be at least 1 cm lower than the adhesion height of the water-based silicone oil on the membrane filament surface (i.e., the first height). This design effectively prevents glue from overflowing the silicone oil protective layer due to misaligned membrane filaments, thereby preventing adhesion between membrane filaments and ensuring the freedom of movement of the membrane filaments.

[0046] Furthermore, the first depth is 5-20 mm.

[0047] When the first depth is less than 5 mm, the bursting strength of the free end package is difficult to reach the minimum standard of 0.4 MPa; when the first depth exceeds 20 mm, unnecessary loss of membrane wire material and packaging glue will be caused.

[0048] Typically but not limitatively, the first depth may be, for example, 5 mm, 8 mm, 10 mm, 12 mm, 15 mm, 18 mm or 20 mm, or any value within the range of 5 mm to 20 mm.

[0049] Furthermore, the mass concentration of the aqueous silicone oil solution is 5-20%.

[0050] The mass concentration of the aqueous silicone oil solution needs to be controlled within an appropriate range: when the concentration is higher than 20%, although it can significantly improve the demolding effect, it will lead to increased production costs; on the contrary, if the concentration is lower than 5%, it will be difficult to effectively prevent the adhesion between the membrane filament and the glue, which will lead to demolding failure.

[0051] Typically but not limitatively, the mass concentration of the aqueous silicone oil solution can be, for example, 5%, 8%, 10%, 12%, 15%, 18% or 20%, or any value within the range of 5% to 20%.

[0052] And / or, the aqueous silicone oil includes at least one of polyether-modified silicone oil, amino-modified silicone oil, carboxyl-modified silicone oil and hydroxyl-modified silicone oil.

[0053] Silicone oil can isolate the membrane filaments from the encapsulating glue, making it easy to pull out the cured membrane filaments. However, silicone oil remaining on the membrane filaments will contaminate the membrane filaments and be difficult to remove. Using water-based silicone oil can overcome this shortcoming.

[0054] Furthermore, the packaging glue includes at least one of epoxy resin glue, polyurethane glue, phenolic resin glue, polyisocyanate glue, polyvinyl acetate glue, polyethylene-vinyl acetate glue, acrylate glue, polystyrene glue, alkyd resin glue, and cellulose glue.

[0055] A second aspect of the present invention provides a hollow fiber membrane bundle, which is composed of a plurality of hollow fiber membrane filaments;

[0056] The hollow fiber membrane comprises a sealed end and an open end at both ends of the membrane;

[0057] The sealing end is sealed using the packaging method described in the first aspect.

[0058] The hollow fiber membrane bundle provided by the present invention, in view of the advantages of the above-mentioned packaging method, reduces the preparation cost of the prepared hollow fiber membrane bundle, reduces the use cost of downstream industries, and promotes the development of downstream industries.

[0059] Furthermore, the diameter of the hollow fiber membrane is 0.2~5mm.

[0060] Typically but not limitatively, the diameter of the hollow fiber membrane can be, for example, 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm or 5 mm, or any value within the range of 0.2 mm to 5 mm.

[0061] Furthermore, the material of the hollow fiber membrane includes at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polysulfone (PSF), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polyacrylonitrile (PAN) and polyisoprene (PMP).

[0062] The present invention is further illustrated below by specific examples and comparative examples. However, it should be understood that these examples are merely for the purpose of further explanation and should not be construed as limiting the present invention in any form. The raw materials used in the examples and comparative examples of the present invention, unless otherwise specified, were prepared under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0063] Example 1

[0064] In this embodiment, the free ends of the hollow fiber membrane bundle are encapsulated, and the specific method is as follows:

[0065] (1) The free end of the hollow fiber membrane bundle after finishing is sealed, and the quick-drying glue is evenly applied to the cut end of the membrane wire by brushing, with a brushing height of 3 mm.

[0066] (2) After the quick-drying glue is completely cured, immerse the glued end into an amino-modified silicone oil solution with a mass concentration of 10%, and control the immersion depth to 25 mm.

[0067] (3) Take out the membrane bundle after dipping, dry it in the air and then cut off the glue-coated end with a length of 5 mm to ensure that the inner pores of the hollow fiber membrane are completely exposed.

[0068] (4) Insert the trimmed membrane bundle into the encapsulation glue, control the immersion depth to 8mm, and let it stand until it is completely cured.

[0069] (5) Slowly pull the membrane bundle vertically out of the solidified glue to obtain a finished hollow fiber membrane bundle with a free-end encapsulation structure.

[0070] Example 2

[0071] In this embodiment, the free ends of the hollow fiber membrane bundle are encapsulated, and the specific method is as follows:

[0072] (1) The free end of the hollow fiber membrane bundle after finishing is sealed, and the quick-drying glue is evenly applied to the cut end of the membrane wire by brushing, with a brushing height of 10 mm.

[0073] (2) After the quick-drying glue is completely cured, immerse the glued end into an amino-modified silicone oil solution with a mass concentration of 10%, and control the immersion depth to 30 mm.

[0074] (3) Take out the membrane bundle after dipping, dry it in the air and then cut off the glue-coated end with a length of 12 mm to ensure that the inner pores of the hollow fiber membrane are completely exposed.

[0075] (4) Insert the trimmed membrane bundle into the encapsulation glue, control the immersion depth to 5mm, and let it stand until it is completely cured.

[0076] (5) Slowly pull the membrane bundle vertically out of the solidified glue to obtain a finished hollow fiber membrane bundle with a free-end encapsulation structure.

[0077] Example 3

[0078] In this embodiment, the free ends of the hollow fiber membrane bundle are encapsulated, and the specific method is as follows:

[0079] (1) The free end of the hollow fiber membrane bundle after finishing is sealed, and the quick-drying glue is evenly applied to the cut end of the membrane wire by brushing, with a brushing height of 3 mm.

[0080] (2) Immerse the free end in an amino-modified silicone oil solution with a mass concentration of 10%, and control the immersion depth to 40 mm.

[0081] (3) Take out the membrane bundle after dipping, dry it in the air and then cut off the glue-coated end with a length of 5 mm to ensure that the inner pores of the hollow fiber membrane are completely exposed.

[0082] (4) Insert the trimmed membrane bundle into the encapsulation glue, control the immersion depth to 20 mm, and let it stand until it is completely cured.

[0083] (5) Slowly pull the membrane bundle vertically out of the solidified glue to obtain a finished hollow fiber membrane bundle with a free-end encapsulation structure.

[0084] Example 4

[0085] In this embodiment, the free ends of the hollow fiber membrane bundle are encapsulated, and the specific method is as follows:

[0086] (1) The free end of the hollow fiber membrane bundle after finishing is sealed, and the quick-drying glue is evenly applied to the cut end of the membrane wire by brushing, with a brushing height of 3 mm.

[0087] (2) Immerse the free end in an amino-modified silicone oil solution with a mass concentration of 10%, and control the immersion depth to 20 mm.

[0088] (3) Take out the membrane bundle after dipping, dry it in the air and then cut off the glue-coated end with a length of 5 mm to ensure that the inner pores of the hollow fiber membrane are completely exposed.

[0089] (4) Insert the trimmed membrane bundle into the encapsulation glue, control the immersion depth to 10 mm, and let it stand until it is completely cured.

[0090] (5) Slowly pull the membrane bundle vertically out of the solidified glue to obtain a finished hollow fiber membrane bundle with a free-end encapsulation structure.

[0091] Example 5

[0092] In this embodiment, the free ends of the hollow fiber membrane bundle are encapsulated, and the specific method is as follows:

[0093] (1) The free end of the hollow fiber membrane bundle after finishing is sealed, and the quick-drying glue is evenly applied to the cut end of the membrane wire by brushing, with a brushing height of 3 mm.

[0094] (2) Immerse the free end in an amino-modified silicone oil solution with a mass concentration of 10%, and control the immersion depth to be 10 mm.

[0095] (3) Take out the membrane bundle after dipping, dry it in the air and then cut off the glue-coated end with a length of 5 mm to ensure that the inner pores of the hollow fiber membrane are completely exposed.

[0096] (4) Insert the trimmed membrane bundle into the encapsulation glue, control the immersion depth to 10 mm, and let it stand until it is completely cured.

[0097] (5) Since the length of the membrane filaments impregnated with water-based silicone oil after cutting is only 5 mm, which is lower than the immersion depth of the packaging glue, the membrane bundle cannot be pulled out of the solidified glue.

[0098] Example 6

[0099] In this embodiment, the free ends of the hollow fiber membrane bundle are encapsulated, and the specific method is as follows:

[0100] (1) The free end of the hollow fiber membrane bundle after finishing is sealed, and the quick-drying glue is evenly applied to the cut end of the membrane wire by brushing, with a brushing height of 3 mm.

[0101] (2) Immerse the free end in an amino-modified silicone oil solution with a mass concentration of 10%, and control the immersion depth to 15 mm.

[0102] (3) Take out the membrane bundle after dipping, dry it in the air and then cut off the glue-coated end with a length of 5 mm to ensure that the inner pores of the hollow fiber membrane are completely exposed.

[0103] (4) Insert the trimmed membrane bundle into the encapsulation glue, control the immersion depth to 10 mm, and let it stand until it is completely cured.

[0104] (5) Slowly pull the membrane bundle vertically out of the solidified glue to obtain a finished hollow fiber membrane bundle with a free-end encapsulation structure.

[0105] Test Case

[0106] The hollow fiber membrane bundle after packaging in the embodiment was subjected to a bursting strength test, and the obtained data are shown in Table 1 below.

[0107] Table 1

[0108]

[0109] As can be seen from Table 1, in Example 1, the difference between the first height and the first depth is 12 mm, the first depth is 8 mm, and the bursting strength of the free-end packaging structure is 0.47 MPa, which meets the product standards and usage requirements and is a relatively reasonable implementation scheme. In Example 2, the difference between the first height and the first depth is 13 mm, the first depth is 5 mm, and the bursting strength of the free-end packaging structure is 0.41 MPa, which meets the product standards and usage requirements. However, in Example 2, the quick-drying glue is applied to the cutting end of the film wire at a height of 10 mm, which is too high and wastes the quick-drying glue, water-based silicone oil, and film wire. In Example 3, the difference between the first height and the first depth is 15 mm, the first depth is 20 mm, and the bursting strength of the free-end packaging structure is 0.68 MPa, which meets the product standards and usage requirements and can be used for products with slightly higher bursting strength requirements. In Example 4, the difference between the first height and the first depth was 5 mm, the first depth was 10 mm, and the burst strength of the free-end packaging structure was 0.51 MPa, meeting product standards and usage requirements. However, in Example 4, the membrane filaments showed a small amount of slight adhesion, which affected the membrane filaments' freedom of movement. In Example 5, the difference between the first height and the first depth was -5 mm, and the first depth was 10 mm. The membrane bundle could not be pulled out of the cured glue, failing to meet product standards and usage requirements. In Example 6, the difference between the first height and the first depth was 0 mm, and the first depth was 10 mm. The burst strength of the free-end packaging structure was 0.50 MPa, and the membrane filaments showed partial adhesion, which affected the membrane filaments' freedom of movement and failed to meet product standards and usage requirements.

[0110] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-described embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. Such modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for encapsulating the free end of a hollow fiber membrane, characterized in that: The following steps are involved: A. Cap the free end of the hollow fiber membrane bundle and immerse it in an aqueous silicone oil solution. After drying, cut the end to expose the inner pores of the hollow fiber membrane. B. inserting the free end after the primary cutting into encapsulation glue for curing, and then removing the free end to obtain an encapsulated free end; In step A, after being immersed in the aqueous silicone oil solution, the aqueous silicone oil layer formed at the free end has a first height after the end is cut once; In step B, the insertion depth into the packaging glue is a first depth; and the first height is greater than the first depth.

2. The packaging method according to claim 1, wherein: The first height is greater than the first depth by more than 1 cm.

3. The packaging method according to claim 1 or 2, characterized in that: The first depth is 5-20 mm.

4. The packaging method according to claim 1, wherein: The mass concentration of the aqueous silicone oil solution is 5-20%; And / or, the aqueous silicone oil includes at least one of polyether-modified silicone oil, amino-modified silicone oil, carboxyl-modified silicone oil and hydroxyl-modified silicone oil.

5. The packaging method according to claim 1, wherein: The packaging glue includes at least one of epoxy resin glue, polyurethane glue, phenolic resin glue, polyisocyanate glue, polyvinyl acetate glue, polyethylene-vinyl acetate glue, acrylate glue, polystyrene glue, alkyd resin glue, and cellulose glue.

6. A hollow fiber membrane bundle, characterized in that: It is composed of several hollow fiber membranes; The hollow fiber membrane comprises a sealed end and an open end at both ends of the membrane; The sealed end is sealed using the packaging method according to any one of claims 1 to 5.

7. The hollow fiber membrane bundle according to claim 6, characterized in that The diameter of the hollow fiber membrane is 0.2-5 mm.

8. The hollow fiber membrane bundle according to claim 6, characterized in that The material of the hollow fiber membrane includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethersulfone, polysulfone, polypropylene, polyethylene, polyvinyl chloride, polyacrylonitrile and polyisoprene.

Images