Disclosure of Invention
In view of this, it is necessary to provide a hollow fiber membrane encapsulation method for solving the problem that dispersion is difficult after the free end of the hollow fiber membrane is encapsulated.
The invention provides a hollow fiber membrane packaging method, which comprises the following steps:
fixing a plurality of hollow fiber membranes to each other in a state that a plurality of first ends of the plurality of hollow fiber membranes are flush with each other to form a hollow fiber membrane set, wherein the plurality of first ends of the plurality of hollow fiber membranes together form a first set end of the hollow fiber membrane set;
pressing a thixotropic potting adhesive into the first collection ends of the collection of hollow fiber membranes, the potting adhesive comprising a volatile solvent;
applying air flow to the first collection end to volatilize the volatile solvent in the packaging adhesive;
applying an external force to the first collection ends to cause the potting adhesive between the first ends of the plurality of hollow fiber membranes to fall off; and
curing the potting adhesive of the first collection end of the collection of hollow fiber membranes.
In one embodiment, the step of pressing thixotropic potting adhesive into the first collection end of the collection of hollow fiber membranes comprises:
placing the collection of hollow fiber membranes horizontally; and
and pressing the distorted packaging adhesive attached to the substrate into the first collecting end along the horizontal direction.
In one embodiment, the packaging adhesive further comprises a nanoscale inorganic filler, and the particle size of the nanoscale inorganic filler is less than 100 nm.
In one embodiment, the nanoscale inorganic filler is 5-8% by mass.
In one embodiment, the nanoscale inorganic filler is fumed nanosilica.
In one embodiment, the volatile solvent is at least one of acetone, butanone, tetrahydrofuran, and ethyl acetate.
In one embodiment, the volatile solvent is 5-15% by weight.
In one embodiment, the volatile solvent is acetone.
In one embodiment, the flow rate of the gas stream is 1m/s to 5 m/s.
In one embodiment, the length of the potting adhesive extending from the first ends to the hollow inner bores of the hollow fiber membranes is greater than or equal to 8 mm.
In one embodiment, the curing is room temperature curing or microwave heating curing.
In one embodiment, the microwave heating power is more than 500W/m2。
In one embodiment, the packaging adhesive is polyurethane adhesive or epoxy adhesive.
In one embodiment, the packaging adhesive further comprises an anti-hollow material capable of preventing a hollow structure from being formed after curing, wherein the anti-hollow material is a toughening agent or a prepolymer.
In one embodiment, the number of hollow fiber membranes in the collection of hollow fiber membranes is greater than 500.
According to the hollow fiber membrane packaging method, the packaging glue containing volatile solvent in a thixotropic state is used for packaging, the volatile solvent is volatilized by using air flow, the bonding force of the packaging glue is reduced, the packaging glue among the first ends of the hollow fiber membranes can be easily separated by applying external force, so that the hollow fiber membranes are not mutually adhered any more and can be automatically dispersed after the fixation is released, and the problem that the dispersion of the free ends of the hollow fiber membranes is difficult after the packaging is solved.
In a preferred embodiment, the hollow fiber membrane packaging method disclosed by the invention has the advantages that the number of packaged hollow fiber membranes can exceed 500, the single packaging time can be less than 30 seconds, the packaging time per ten thousand hollow fiber membranes can be less than 15 minutes, the packaging efficiency is very high, and the hollow fiber membrane packaging method is suitable for large-scale industrial production.
In a preferred embodiment, the hollow fiber membrane adopts corrosion-resistant epoxy glue or polyurethane glue as packaging glue, and the packaged hollow fiber membrane can resist strong acid and strong alkali cleaning, so that the application environment and the range of the hollow fiber membrane are expanded.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below by way of embodiments with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, an embodiment of the present invention provides a hollow fiber membrane packaging method, including the following steps:
s1, fixing a plurality of hollow fiber membranes 10 to each other in a state that a plurality of first ends 13 of the plurality of hollow fiber membranes 10 are flush with each other to form a hollow fiber membrane assembly 50, wherein the plurality of first ends 13 of the plurality of hollow fiber membranes together form a first assembly end 52 of the hollow fiber membrane assembly;
s2, pressing thixotropic potting adhesive 54 into the first collection end 52 of the collection of hollow fiber membranes 50, the potting adhesive 54 comprising a volatile solvent;
s3, applying an air flow 56 to the first collecting end 52 to volatilize the volatile solvent in the packaging adhesive 54;
s4, applying an external force to the first collective end to peel off the potting adhesive 54 between the first ends 13 of the hollow fiber membranes 10; and
s5, curing the potting adhesive 54 of the first collection end 52 of the collection of hollow fiber membranes 50.
According to the hollow fiber membrane packaging method, the packaging glue containing volatile solvent in a thixotropic state is used for packaging, the volatile solvent is volatilized by air flow, after the volatile solvent is volatilized, the bonding force of the packaging glue is reduced, the packaging glue among the first ends of the hollow fiber membranes can be easily separated by applying external force, so that the hollow fiber membranes are not mutually adhered, and can be automatically dispersed after the fixation is released.
The method of embodiments of the present invention may be used with any type of hollow fiber membrane. Fig. 2 shows a hollow fiber membrane 10 prior to potting, comprising a tubular body 11 having a hollow bore 12, a first end 13 and a second end 14. The hollow fiber membrane 10 preferred in the embodiment of the present invention has an inner diameter of 0.6 to 3 mm. The hollow fiber membrane 10 may be a microfiltration membrane or an ultrafiltration membrane, and may be made of high molecular materials such as polyvinyl chloride, polyvinylidene fluoride, polyether sulfone and the like. The micro-filtration membrane or the ultra-filtration membrane has a porous structure, and thus the membrane wall of the hollow fiber membrane 10 is a porous membrane wall having many micro pores as can be seen from fig. 3.
In step S1, the first ends 13 of the plurality of hollow fiber membranes 10 are kept flush with each other. The hollow fiber membrane assembly 50 may be cylindrical as a whole. Preferably, the plurality of hollow fiber membranes are fixed by fixing member 40 at a first position closer to first end 13 and a second position farther from first end so that the plurality of hollow fiber membranes are immovable with respect to each other, forming hollow fiber membrane assembly 50. The method of fixation may preferably be by bundling with fixation elements 40. The first position is preferably at a distance of 10mm to 30mm, more preferably 20mm, from the first end 13, and the second position is preferably at a distance of 40mm to 50mm, more preferably 45mm, from the first end 13. In the hollow fiber membrane module assembly 50, adjacent hollow fiber membranes 10 may be disposed at a distance after contacting each other, and even if the hollow fiber membranes 10 are disposed in contact with each other, a certain gap may be left between the hollow fiber membranes 10 in contact with each other because the hollow fiber membranes 10 are flexible.
The number of hollow fiber membranes 10 in the hollow fiber membrane collection 50 is preferably more than 500.
In one embodiment, the securing element 40 at the first position can be removed before the thixotropic potting compound 54 is pressed into the first collection ends 52 of the collection 50 of hollow fiber membranes to release the securing of the hollow fiber membranes at the first position.
The encapsulation adhesive 54 includes one or more of a monomer, an oligomer, and a polymer capable of undergoing polymerization during curing, and includes a volatile solvent for dissolving or dispersing the monomer, oligomer, and polymer. In some embodiments, the encapsulant 54 further includes additional components, such as one or more of a curing agent, a diluent, a stabilizer, and an accelerator.
Preferably, the thixotropic packaging adhesive 54 further includes a nanoscale inorganic filler, and the particle size of the nanoscale inorganic filler is less than 100 nm; more preferably, the nanoscale inorganic filler is fumed nanosilica. In the thixotropic packaging adhesive 54, the mass percentage of the nanoscale inorganic filler is preferably 5% to 8%. It is due to the physical action of the nanoscale inorganic filler particles that the thixotropic state of the encapsulant 54 is formed. The thixotropic gel 54 will flow only under pressure.
In step S2, the hollow fiber membrane assembly 50 is preferably placed horizontally, and the potting adhesive 54 in a thixotropic state attached to the substrate is preferably pressed into the first assembly end 52 in the horizontal direction.
Pressing the thixotropic potting adhesive 54 into the first gathering end 52, wherein the thixotropic potting adhesive 54 enters the hollow inner holes 12 of the hollow fiber membranes 10, and the length of the thixotropic potting adhesive 54 extending from the first ends 13 to the hollow inner holes 12 of the hollow fiber membranes 10 is greater than or equal to 6mm, and more preferably greater than or equal to 8 mm. The longer the length of the potting adhesive 54 extending to the hollow inner hole 12 of the hollow fiber membrane 10, the firmer the potting adhesive 54 is bonded to the membrane wall of the hollow fiber membrane 10, and the better the potting effect of the hollow fiber membrane 10 is. In addition, the thixotropic potting adhesive 54 also penetrates a small amount between the adjacent first ends 13 of the plurality of hollow fiber membranes 10. A small amount of thixotropic potting adhesive 54 that enters between adjacent first ends 13 of the plurality of hollow fiber membranes 10 is irregularly bonded to the first ends 13. Unlike the case of using the potting adhesive 54 with high fluidity to vertically immerse the first ends 13 of the hollow fiber membranes 10 in the container containing the potting adhesive 54, the thixotropic potting adhesive 54 can adhere to the surface of the substrate to form a layer of material without fluidity, so that the amount of the potting adhesive 54 applied to the first collecting ends 52 of the hollow fiber membrane assemblies 50 can be controlled relatively easily, and particularly, the amount of the potting adhesive 54 entering between the adjacent first ends 13 of the plurality of hollow fiber membranes 10 is small.
The volatile solvent in the thixotropic gel 54 can be quickly volatilized by the airflow 56. Preferably, the volatile solvent is at least one of acetone and butanone. More preferably, the volatile solvent is acetone. In the thixotropic state encapsulation adhesive 54, the mass percentage content of the volatile solvent is preferably 5% to 15%.
In an embodiment, the encapsulation adhesive 54 may further include an inorganic reinforcing powder, such as at least one of nano molecular sieve and sub-nano hollow microsphere, for improving the strength of the encapsulation adhesive 54 after curing.
In an embodiment, the encapsulation adhesive 54 further includes a hollow-proof material for preventing the encapsulation adhesive 54 from generating a hollow structure after being cured, preferably an organic component with a relatively high molecular weight, and in a specific embodiment, the hollow-proof material may include at least one of a toughening agent or a prepolymer. Because the application amount of the thixotropic encapsulant 54 is limited, part of the encapsulant 54 may penetrate into the porous membrane walls of the hollow fiber membrane 10, thereby forming holes in situ, and when the encapsulant 54 originally located in the hollow inner holes 12 of the hollow fiber membrane 10 penetrates into the porous membrane walls of the hollow fiber membrane, the problem of poor encapsulation is easily caused. By increasing the proportion of the hollow-proof material, the amount of the monomer and oligomer with smaller molecular weight in the packaging adhesive 54 is correspondingly reduced, and the problem of untight packaging caused by the fact that too much packaging adhesive 54 permeates into the porous membrane wall of the hollow fiber membrane can be avoided. The anti-voiding material is preferably capable of undergoing a polymerization reaction with other monomers, oligomers and/or polymers during curing to form a stable cross-linked polymeric structure. The content of the hollow-proof material in the packaging adhesive 54 is preferably 10 to 15% by mass. The mass percentage of the hollow-proof material is preferably 10-15%.
The potting adhesive 54 is preferably a polyurethane adhesive or an epoxy adhesive. The polyurethane glue or the epoxy glue can enable the encapsulation of the hollow fiber membrane to resist strong acid or strong alkali, so that the encapsulated hollow fiber membrane is more suitable for application in different environments.
The potting adhesive 54 can change the activity (i.e., the time required for curing at room temperature), the hardness after curing, and the corrosion resistance by adjusting the kind and the ratio of the raw materials, so as to be suitable for hollow fiber membranes 10 of different types and applications in different fields. The conventional hollow fiber membrane 10 can be classified into a thermal hollow fiber membrane and a wet hollow fiber membrane according to the principle of membrane formation. The thermal hollow fiber membrane is a hollow fiber membrane prepared by a thermally induced phase separation method. The wet hollow fiber membrane is a hollow fiber membrane prepared by a dry-wet spinning technology.
In one embodiment, the encapsulating adhesive 54 is a polyurethane adhesive, and the components of the polyurethane adhesive preferably include polyolefin polyol, polyether polyol, modified polyisocyanate, volatile solvent, nanoscale inorganic filler, anti-hollowing material, inorganic reinforcing powder, diluent, stabilizer and accelerator.
Preferably, the mass percentage of the nano-grade inorganic filler is 5-8%, the mass percentage of the volatile solvent is 5-10%, the mass percentage of the hollow-proof material is 10-15%, the mass percentage of the polyolefin polyol is 10-15%, the mass percentage of the polyether polyol is 20-30%, and the mass percentage of the modified polyisocyanate is 10-15%.
The volatile solvent is preferably acetone, the nanoscale inorganic filler is preferably gas-phase nano-silica, the anti-hollow material is preferably a polyurethane elastomer with the molecular weight of 5000-6000, and the inorganic reinforced powder is a molecular sieve.
When in use, all the components of the polyurethane adhesive are uniformly mixed until thixotropic. The hardness of the polyurethane adhesive after curing can reach 50-60D, and the time required for curing under the room temperature condition is 4 h. The polyurethane adhesive is suitable for the thermal hollow fiber membrane 10.
In one embodiment, the packaging adhesive 54 is a polyurethane adhesive, and the components of the polyurethane adhesive preferably include polyolefin polyol, modified polyisocyanate, diisocyanate, volatile solvent, nanoscale inorganic filler, anti-hollowing material, inorganic reinforcing powder, diluent, stabilizer and accelerator.
Preferably, the mass percent of the nano-grade inorganic filler is 5-8%, the mass percent of the volatile solvent is 5-10%, the mass percent of the hollow-proof material is 10-15%, the mass percent of the polyolefin polyol is 30-40%, the mass percent of the modified polyisocyanate is 10-15%, and the mass percent of the diisocyanate is 5-10%.
The volatile solvent is preferably acetone, the nanoscale inorganic filler is preferably gas-phase nano-silica, the anti-hollow material is preferably a polyurethane elastomer with the molecular weight of 8000-10000, and the inorganic reinforced powder is preferably a molecular sieve and sub-nanometer superfine hollow microspheres.
When in use, all the components of the polyurethane adhesive are uniformly mixed until thixotropic. The hardness of the polyurethane adhesive after curing can reach 70-80D, and the time required for curing at room temperature is 3 h. The polyurethane adhesive is also suitable for the thermal hollow fiber membrane 10.
In one embodiment, the encapsulating adhesive 54 is preferably an epoxy adhesive, and the components of the epoxy adhesive include bisphenol a epoxy resin, modified bisphenol F multifunctional epoxy resin, volatile solvent, nanoscale inorganic filler, anti-hollowing material, polyetheramine curing agent, alicyclic amine curing agent, diluent, stabilizer and accelerator.
Preferably, the mass percent of the nano-scale inorganic filler is 5-8%, the mass percent of the volatile solvent is 10-15%, the mass percent of the anti-hollow material is 10-15%, the mass percent of the bisphenol A epoxy resin is 30-45%, and the mass percent of the modified bisphenol F multifunctional epoxy resin is 10-15%.
The volatile solvent is preferably acetone, the nano-scale inorganic filler is preferably gas-phase nano-silica, and the anti-hollow material is preferably a high-temperature-resistant epoxy prepolymer.
When in use, all the components of the epoxy glue are uniformly mixed until thixotropic. The hardness of the cured epoxy adhesive can reach 70-80D, and the curing time at room temperature is 1 h. The epoxy glue is suitable for the wet hollow fiber membrane 10.
A small amount of the thixotropic potting compound 54 enters between the first ends 13 of the hollow fiber membranes 10, because the first ends 13 of the hollow fiber membranes 10 are closer to each other, and the thixotropic potting compound has a certain viscosity, the first ends 13 of the hollow fiber membranes 10 are easily adhered to each other, and the hollow fiber membranes 10 in the hollow fiber membrane assembly 50 cannot be easily dispersed after the thixotropic potting compound 54 is cured.
In step S3, the air flow 56 is applied to the first collecting end 52 to rapidly volatilize the solvent in the potting adhesive 54, thereby reducing the viscosity and the adhesion. In a preferred embodiment, since the potting adhesive 54 contains the nanoscale inorganic filler in an amount of more than 5% by mass, a self-lubricating effect can be generated, and the potting adhesive 54 between the adjacent first ends 13 of the plurality of hollow fiber membranes 10 can easily fall off under the self-lubricating effect of the nanoscale inorganic filler.
In one embodiment, the flow rate of the gas stream 56 is preferably 1m/s to 5m/s, and more preferably, the flow rate of the gas stream 56 is 2m/s to 3 m/s. The airflow 56 may be provided by a high wind system, such as a fan system. The direction of the air flow 56 should flow to the hollow inner holes of the hollow fiber membranes as little as possible, preferably, the direction of the air flow 56 is perpendicular to the length direction of the hollow fiber membrane assembly 50, so that the volatile solvent in the potting adhesive 54 between the first ends 13 of the plurality of hollow fiber membranes 10 is volatilized quickly, and the volatile solvent in the potting adhesive 54 in the hollow inner holes 12 of the hollow fiber membranes 10 is not affected, and the potting adhesive 54 in the hollow inner holes 12 of the hollow fiber membranes 10 still has good adhesive force, and penetrates into the micropores of the porous membrane walls of the hollow fiber membranes 10 in a small amount during curing and crosslinking, and is adhered to the porous membrane walls of the hollow fiber membranes 10 after the operation of step S5 is performed, thereby playing a role of encapsulation.
In step S4, an external force is applied to the first collecting end 50 to peel off the potting adhesive between the first ends of the hollow fiber membranes. The applied external force may be a force generated by manual shaking or vibration of an automated instrument.
In step S5, after the potting adhesive 54 between the first ends 13 of the hollow fiber membranes 10 falls off, the potting adhesive 54 at the first collecting ends 52 of the hollow fiber membrane assemblies 50 is cured, which may be room temperature curing or microwave heating curing. The first collection end 52 of the collection of hollow fiber membranes 50 is preferably heated in a microwave to rapidly cure the potting compound 54. In the curing process, the organic component in the package adhesive 54 undergoes a cross-linking polymerization reaction to form an insoluble and infusible polymer network, and the inorganic component is fixed in the polymer network to form the package plug 20. When the packaging adhesive 54 is cured and crosslinked, a hermetic package is formed in a manner of permeating into the porous membrane wall of the hollow fiber membrane, as shown in fig. 4, as can be seen from comparison with fig. 3, a part of the packaging adhesive 54 enters the micropores of the porous membrane wall of the hollow fiber membrane 10, a lighter part in fig. 4 is the packaging adhesive 54, a darker part is the porous membrane wall, and fig. 4 shows that the micropores of the porous membrane wall are doped with the lighter packaging adhesive 54.
Preferably, the microwave heating power is more than 500W/m2The heating time is 2-3 min.
In one embodiment, in step S5, a plurality of hollow fiber membrane assemblies 50 may be simultaneously placed in a microwave for heating to cure the potting adhesive 54, and preferably 10 hollow fiber membrane assemblies 50 are simultaneously placed in a microwave for heating.
According to the novel hollow fiber membrane packaging method, the single packaging time is less than 30 seconds, the packaging time of every ten thousand membrane filaments is less than 15 minutes, and the packaging efficiency is far higher than 83 hours/ten thousand in the prior art.
In an embodiment, the novel hollow fiber membrane encapsulation method further includes a step of disassembling the hollow fiber membrane assembly 50 after curing the encapsulation adhesive 54, so that the plurality of hollow fiber membranes 10 are separated from each other. Specifically, the fixing member 40 may be removed, i.e., the plurality of hollow fiber membranes 10 may be simply separated from each other.
The hollow fiber membrane packaging method of the invention has the advantages that the effect after packaging is shown in fig. 5, the hollow fiber membrane 10 can be effectively dispersed, and due to the reduction of the volatile viscosity of the volatile solvent and the self-lubricating effect of the nano inorganic filler, the packaging adhesive 54 outside the first end 13 can be peeled off through simple mechanical shaking, the first end 13 of the cured hollow fiber membrane 10 is smooth and clean, and no residual packaging adhesive 54 is adhered.
Referring to fig. 6 and 7, an embodiment of the invention further provides an encapsulated hollow fiber membrane 30, where the encapsulated hollow fiber membrane 30 includes a hollow fiber membrane 10 and an encapsulated plug 20 after curing;
the hollow fiber membranes 10 have a first end 13 and a second end 14;
the first end 13 is encapsulated by the encapsulating plug 20, the second end 14 is an open end, and the encapsulating plug 20 penetrates into the hollow inner bore 12 of the hollow fiber membrane 10 from the first end.
For better sealing, the sealing plug 20 preferably extends in the hollow bore for a length greater than or equal to 8 mm.
In the embodiment of the present invention, the sealing plug 20 is cylindrical, and the sealing plug 20 extends into the hollow inner hole 12 of the hollow fiber membrane 10 and does not extend to the outer side wall of the first end 13 of the hollow fiber membrane 10.
The embodiment of the invention also provides a single-end fixed hollow fiber membrane module, which comprises the encapsulated hollow fiber membrane 30.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.