Manufacturing method of instantaneous pressure relief spinning filter membrane supporting body membrane, product and application of instant pressure relief spinning filter membrane supporting body membrane

Abstract

The invention discloses a manufacturing method of an instantaneous pressure relief spinning filter membrane support membrane, a product and application thereof, and belongs to the technical field of filter membranes for separation. The instantaneous pressure-relief spinning filter membrane support membrane is prepared by the following steps: by taking a melt-solvent complex containing 6-14wt% of high-density polyethylene, 5-13wt% of linear low-density polyethylene, 0.5-2wt% of butyl suberic acid and the balance of a spinning solvent as a spinning solution, preparing a non-woven fabric membrane through an instantaneous pressure-relief spinning technology, bonding silver ions on the surface of the formed non-woven fabric membrane, and then carrying out melt spinning on the non-woven fabric membrane to obtain the instantaneous pressure-relief spinning filter membrane support membrane. And reducing the stably bonded silver ions into nano-silver. After the support body membrane is compounded with a polyethylene filter membrane in a hot pressing manner, the obdurability of the polyethylene microporous filter membrane can be effectively improved, and very small thickness size and weight can be maintained, so that higher requirements of part of precise instruments on thickness, weight and mechanical strength can be met.

Description

Technical Field

[0001] The present invention belongs to the technical field of filter membranes for separation, and in particular relates to a method for manufacturing an instantaneous pressure-release spun filter membrane support membrane, its products and applications, and specifically relates to a method for manufacturing an instantaneous pressure-release spun filter membrane support membrane, a polyethylene composite filter membrane containing the instantaneous pressure-release spun filter membrane support membrane and its applications. Background Art

[0002] Polyethylene (PE) microporous membranes are widely used in water treatment, air filtration, and medical fields due to their low cost, easy processing, and good chemical stability. However, microporous filtration generally involves a fast filtration rate and fine screening process. Common PE materials have poor mechanical properties, which can easily cause the microporous membrane to rupture due to the pressure generated by filtration, resulting in a short service life. At the same time, common PE materials have insufficient antibacterial properties, which can easily cause microorganisms to be contaminated after contact with the treatment solution, causing pore blockage and contamination of the sample to be filtered.

[0003] Therefore, the performance of conventional polyethylene microporous filter membranes is greatly limited, resulting in unsatisfactory actual effects in microporous filtration. Summary of the invention

[0004] The present application discloses a method for manufacturing an instantaneous pressure-release spinning filter membrane support membrane, a product thereof and an application thereof, which are used to solve the technical problems of poor mechanical strength and insufficient antibacterial ability of conventional polyethylene microporous filter membranes.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] In a first aspect, the present application provides a method for manufacturing an instantaneous pressure-release spinning filter membrane support membrane, the steps of which include:

[0007] preparing a melt-solvent composite;

[0008] Using the melt-solvent complex as spinning solution, a nonwoven membrane is prepared by instantaneous pressure release spinning technology;

[0009] The non-woven fabric membrane is sequentially immersed in a modification solution containing silver nitrate for immersion modification, and immersed in an aqueous solution of sodium triacetoxyborohydride for immersion reduction, and then dried to obtain an instantaneous pressure release spinning filter membrane support membrane;

[0010] Wherein, the raw material components of the melt-solvent complex are:

[0011] (a) High-density polyethylene 6-14 wt%, with a melt index of 6-8 g / 10 min at 190 °C and 2.16 kg load;

[0012] (b) 5-13 wt% linear low-density polyethylene, whose melt index at 190 °C and 2.16 kg load is 20-24 g / 10 min;

[0013] (c) 0.5-2 wt% butyl suberic acid; (d) The spinning solvent is supplemented to 100 wt%.

[0014] According to the manufacturing method disclosed in the present application, the spinning solvent is selected from at least one of tetrafluorodichloroethane, difluoromonochloromethane, n-hexane, butane, pentene, heptane, octane, cyclohexane, dichloromethane, carbon tetrachloride, chloroform, chloromethane, ethyl chloride, trichlorofluoromethane, dichlorotrifluoroethane, pentafluoropropane, heptafluoropropane, perfluorohexane, perfluoroheptane, and octafluorocyclopentane.

[0015] According to the manufacturing method disclosed in the present application, the preparation of the melt-solvent complex comprises:

[0016] The high-density polyethylene, linear low-density polyethylene, butyl suberic acid and spinning solvent are mixed, heated to 210-230° C. and pressurized to 10-12 MPa in an inert atmosphere, and stirred until the temperature and pressure are stable to obtain a melt-solvent composite.

[0017] According to the manufacturing method disclosed in the present application, the preparation of the non-woven membrane by instantaneous pressure release spinning technology comprises:

[0018] The spinning solution is added into a supercritical reactor with a nozzle aperture of 1 to 3 μm, and supercritical carbon dioxide is injected under stirring to obtain a stable supercritical fluid;

[0019] The supercritical fluid is instantaneously released into the atmosphere at a jet flow rate of 10000-12000 m / min, stretched and opened by high-pressure air to form an ultrafine fiber web, and then cold pressed and hot rolled to obtain a non-woven fabric membrane.

[0020] According to the manufacturing method disclosed in the present application, the modified liquid containing silver nitrate comprises an ether aqueous solution and silver nitrate dissolved in the ether aqueous solution with a molar concentration of 0.3 to 0.5 mol / L, wherein the ether aqueous solution is a mixture of ether and water in a volume ratio of (3 to 4): (6 to 7);

[0021] And, the molar concentration of the aqueous solution of sodium triacetoxyborohydride is 0.5-0.8 mol / L.

[0022] In a second aspect, the present application also provides an instantaneous pressure release spinning filter membrane support membrane produced by the manufacturing method of the present invention.

[0023] In a third aspect, the present application further provides a polyethylene composite filter membrane, which comprises a polyethylene microporous filter membrane and the instantaneous pressure-release spinning filter membrane support membrane of the present invention which is hot-pressed and composited on the polyethylene microporous filter membrane.

[0024] The polyethylene composite filtration membrane disclosed in the present application at least comprises:

[0025] (1) Resistance to hydrostatic pressure of 30,000 to 40,000 Pa; and

[0026] (2) Maintain 4000~5000 L / m at 0.2 MPa pressure 2 ·h of pure water flux.

[0027] In a fourth aspect, the present application also provides a method for manufacturing the polyethylene composite filtration membrane of the present invention, the steps of which include:

[0028] After the polyethylene microporous filter membrane is laminated to the surface to be laminated of the instantaneous pressure-release spinning filter membrane support membrane, heat-pressing and heat-sealing are performed by double-roll hot-pressing laminating equipment;

[0029] Among them, the hot pressing temperature is 160~170 ℃; the hot pressing pressure is 20~22 bar.

[0030] In a fifth aspect, the present application also provides the use of the polyethylene composite filtration membrane of the present invention in the filtration treatment of polar chemical solutions or aqueous solutions.

[0031] Compared with the prior art, the advantages or beneficial effects of the embodiments of the present application at least include:

[0032] The manufacturing method provided by the present invention prepares a non-woven membrane by instantaneously releasing the pressure using a melt-solvent complex containing the raw material components as a spinning solution, and bonding silver ions to the surface of the formed non-woven membrane, and reducing the bonded silver ions to nano-silver by sodium triacetoxyborohydride. On the one hand, the strength-toughness balance of the non-woven membrane is effectively achieved through a specific combination of high-density polyethylene and linear low-density polyethylene, so that the mechanical strength of the non-woven membrane is greatly improved; on the other hand, the high-density polyethylene and the linear low-density polyethylene can form an interpenetrating structure, effectively enhancing the interface bonding force, thereby giving the non-woven membrane excellent mechanical support strength through the combined action of functional structure integration; on the other hand, the rheological properties of the spinning solution can be adjusted, the film-forming efficiency can be effectively improved, and the pore size distribution can be optimized, so that the formed non-woven membrane has a pore size matching the polyethylene microporous filter membrane, and the polyethylene composite filter membrane can be given excellent filtration efficiency; on the other hand, the non-woven membrane can be given a continuous and stable antibacterial effect, so that the problem of easy rupture and microbial adhesion of the polyethylene microporous filter membrane can be effectively solved through the combined action of the above functions, and the application scenarios of the polyethylene microporous filter membrane are expanded. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in this application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 This is a SEM image of the polyethylene composite filtration membrane prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0035] The technical solution 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 part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of this application.

[0036] In the relevant description of this application, the term "and / or" is used to describe the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, B exists alone, and A and B exist at the same time. A and B can be singular or plural.

[0037] In the relevant description of the present application, the term "at least one" refers to one or more, wherein "plurality" refers to two or more. "At least one of the following" or similar descriptions thereof refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of A, B or C", or "at least one of A, B and C", all mean one of A, B, C, or A+B, or A+C, or B+C, or A+B+C, wherein A, B, C can be single or multiple, respectively.

[0038] In the relevant description of this application, the order of serial numbers does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute a limitation on the implementation process of the present invention.

[0039] In the relevant description of the application, the numerical range is understood to also specifically disclose each intermediate value between the upper and lower limits of the range. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range also belongs to the disclosure of the application. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0040] Unless otherwise stated, the technical / scientific terms used in this application have the meanings and / or interpretations that are generally known to those of ordinary skill in the art. Although this application only describes possible materials and / or methods of the present invention, any materials and / or methods similar or equivalent to the present invention may also be used in the implementation or experiment disclosed in this application. In addition, all documents mentioned in this application are incorporated by reference to disclose and describe the materials and / or methods related to the documents. In the event of a conflict with any incorporated document, the technical content of the present invention shall prevail.

[0041] In a first aspect, the present disclosure provides, by way of example, a method for manufacturing a supporting membrane material for an instantaneous pressure release microfiltration membrane, comprising steps S1 to S3:

[0042] S1: preparation of melt-solvent composite;

[0043] S2: Using the melt-solvent complex prepared in the previous step as a spinning solution, a non-woven membrane is prepared by instantaneous pressure release spinning technology;

[0044] S3: The non-woven fabric prepared in the previous step is sequentially immersed in a modification solution containing silver nitrate for modification, and immersed in an aqueous solution of sodium triacetoxyborohydride for reduction, and then dried to obtain an instantaneous pressure release spinning filter membrane support membrane;

[0045] Wherein, the raw material components of the melt-solvent complex are:

[0046] (a) High-density polyethylene 6-14 wt%, with a melt index of 6-8 g / 10 min at 190 °C and 2.16 kg load;

[0047] (b) 5-13 wt% linear low-density polyethylene, whose melt index at 190 °C and 2.16 kg load is 20-24 g / 10 min;

[0048] (c) 0.5-2 wt% butyl suberic acid; (d) The spinning solvent is supplemented to 100 wt%.

[0049] It should be noted that the present disclosure does not specifically limit the specific parameters of drying, and is based on the ability to fully remove the residual liquid. The drying parameters of 70~90℃ / 20~60 min can be selected as an example; at the same time, the present disclosure does not specifically limit the specific sources of high-density polyethylene and linear low-density polyethylene, and can be exemplified by 7260 type polyethylene with a melt index of 7 g / 10 min (190℃ / 2.16 kg) (purchased from Braskem), and 7144 linear low-density polyethylene with a melt index of 22 g / 10 min (190℃ / 2.16 kg) (purchased from China Petrochemical Corporation).

[0050] In summary, the present invention uses a melt-solvent complex containing the raw material components as a spinning solution for instantaneous pressure release, bonds silver ions to the surface of the formed non-woven fabric, and reduces the stably bonded silver ions to nano-silver, thereby producing a support membrane with excellent mechanical support strength, good antibacterial effect, and suitable for polyethylene microporous filter membrane. Specifically:

[0051] (1) The present invention uses a composition of high-density polyethylene and linear low-density polyethylene as a raw material and combines it with a sequential pressure release spinning process to prepare a non-woven membrane. First, the high-density polyethylene with a rigid skeleton support capacity can cooperate with the linear low-density polyethylene with good ductility to effectively achieve the strength-toughness balance of the formed non-woven membrane, giving the non-woven membrane excellent mechanical support strength; second, the coupled sequential pressure release spinning technology can induce rapid rearrangement of the molecular chains and form an interpenetrating network of high-density polyethylene microcrystals and linear low-density polyethylene amorphous regions, effectively enhancing the interface bonding strength, thereby maximizing the skeleton support strength of the non-woven membrane through the integrated coupling of material structure and function, and the non-woven membrane prepared by instantaneous pressure release is relatively thin (the thickness is generally 110-180 μm), which can keep the polyethylene composite filter membrane still very small in thickness and weight while meeting the same strength and toughness, meeting the high requirements of some precision instruments for thickness, weight and mechanical strength;

[0052] (2) The present invention can effectively regulate the rheological behavior of the spinning solution by compounding the combined raw materials of high-density polyethylene and linear low-density polyethylene contained therein with the spinning solvent, effectively improve the film-forming efficiency and optimize the pore size distribution, so that the formed non-woven fabric membrane has a pore size suitable for the polyethylene microporous filter membrane, and maintains the excellent filtration efficiency of the polyethylene composite filter membrane;

[0053] (3) The present invention introduces butyl suberic acid into the melt-solvent complex containing the raw material components so that a large number of carboxyl groups are bound to the surface of the formed non-woven fabric membrane, thereby utilizing the oxidation characteristics of silver nitrate to easily extract hydrogen atoms from the carboxylic acid through impregnation so that silver ions replace hydrogen ions and stably bond with the carboxyl groups. Then, the silver ions can be reduced to stably bound nanosilver particles by impregnation with an aqueous solution of sodium triacetoxyborohydride. The stably bound nanosilver particles can continuously release antibacterial active molecules, thereby effectively preventing microbial adhesion and ensuring good flowability of the polyethylene composite filter membrane. At the same time, the non-polar alkyl group of butyl suberic acid can also promote its dispersion in the polar spinning solution, which helps to evenly distribute the stably bound nanosilver particles on the non-woven fabric membrane, further optimizing the antibacterial effect.

[0054] In the exemplary scheme of the present disclosure, the spinning solvent can be selected from at least one of tetrafluorodichloroethane, difluoromonochloromethane, n-hexane, butane, pentene, heptane, octane, cyclohexane, dichloromethane, carbon tetrachloride, chloroform, chloromethane, ethyl chloride, trichlorofluoromethane, dichlorotrifluoroethane, pentafluoropropane, heptafluoropropane, perfluorohexane, perfluoroheptane, and octafluorocyclopentane, among which a mixed solvent of tetrafluorodichloroethane and difluoromonochloromethane is more preferred.

[0055] In the exemplary embodiment of the present disclosure, the preparation of the melt-solvent complex in step S1 preferably comprises:

[0056] After the high-density polyethylene, linear low-density polyethylene, butyl suberic acid and spinning solvent are mixed, they are heated to 210-230 ° C in an inert atmosphere, pressurized to 10-12 MPa, and stirred until the temperature and pressure are stable to obtain a melt-solvent complex. For example, high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE) and butyl suberic acid can be mixed evenly for use, and tetrafluorodichloroethane and difluoromonochloromethane can be mixed evenly for use; then the two mixed materials are added to the reactor and mixed evenly, preheated to 170 ° C, nitrogen is introduced and pressurized to 10 MPa, and finally heated to 210 ° C, and stirred in a closed state for 3 hours to stabilize the temperature and pressure to obtain a melt-solvent complex, that is, a spinning solution.

[0057] In an exemplary embodiment of the present disclosure, preparing a nonwoven membrane by instantaneous pressure release spinning technology in step S2 comprises:

[0058] The spinning solution is added into a supercritical reactor with a nozzle aperture of 1 to 3 μm, and supercritical carbon dioxide is injected under stirring to obtain a stable supercritical fluid;

[0059] The supercritical fluid is instantaneously released into the atmosphere at a jet flow rate of 10000-12000 m / min, stretched and opened by high-pressure air to form an ultrafine fiber web, and then cold pressed and hot rolled to obtain a non-woven fabric membrane.

[0060] In the exemplary scheme of the present disclosure, the silver nitrate-containing modifying solution in step S3 comprises an ether aqueous solution and silver nitrate dissolved in the ether aqueous solution at a molar concentration of 0.3-0.5 mol / L, wherein the ether aqueous solution is a mixture of ether and water in a volume ratio of (3-4):(6-7);

[0061] And, the molar concentration of the aqueous solution of sodium triacetoxyborohydride is 0.5-0.8 mol / L.

[0062] In the second aspect, the present disclosure also provides an instantaneous pressure-release spun filter membrane support membrane manufactured by the manufacturing method of the present invention. Among them, since the manufacturing method of the present invention can improve the two-phase interface bonding strength of high-density polyethylene and linear low-density polyethylene and achieve the strength-toughness balance of the polyethylene non-woven membrane, and at the same time can stably bind the nano-silver antibacterial component to the surface of the manufactured polyethylene non-woven membrane, the instantaneous pressure-release spun filter membrane support membrane manufactured by the present invention has excellent overall mechanical support strength, good antimicrobial adhesion performance and can well match the pore size of the polyethylene microporous filter membrane; at the same time, the instantaneous pressure-release spun filter membrane support membrane is a single-material all-polyethylene-based membrane material, and the subsequent recycling and processing process is simple and can reduce the waste discharge of the processing process, which is conducive to recycling and reuse, reduces pollution to the natural environment, and has environmental benefits.

[0063] In a third aspect, the present disclosure further provides a polyethylene composite filter membrane, which comprises a polyethylene microporous filter membrane and a support membrane hot-pressed and composited on the polyethylene microporous filter membrane, wherein the support membrane is selected as the instantaneous pressure-release spinning filter membrane support membrane manufactured by the manufacturing method of the present invention.

[0064] It should be noted that the present disclosure does not specifically limit the specific source and pore size of the polyethylene microporous filter membrane. The polyethylene microporous filter membrane with common pore size available on the market can be selected as a small pore size polyethylene microporous filter membrane with a pore size of 0.1~1 μm, for example, the STERLITECH polyethylene microporous filter membrane with a pore size of 0.45 μm and a thickness of 125 μm selected in the present invention.

[0065] The present invention not only effectively improves the strength and toughness of the filter membrane by hot-pressing and compounding the instantaneous pressure-release spinning filter membrane support membrane of the present invention on a polyethylene filter membrane as a skeleton support, but also enables the filter membrane to still maintain a very small thickness and weight, meeting the high requirements of some precision instruments for thickness, weight and mechanical strength. At the same time, the use of hot-pressing glue-free compounding can avoid the reaction between glue and chemicals, ensuring a good filtering effect. In addition, the present invention manufactures a single-material all-polyethylene composite filter membrane, and the subsequent recycling and processing process is simple, which can reduce the amount of waste discharged in the processing process, is conducive to recycling and reuse, reduces pollution to the natural environment, and has environmental benefits.

[0066] In a fourth aspect, the present disclosure also provides a method for manufacturing the polyethylene composite filtration membrane of the present invention, the steps of which include:

[0067] After the polyethylene microporous filter membrane is laminated to the surface to be laminated of the instantaneous pressure-release spinning filter membrane support membrane, heat-pressing and heat-sealing are performed by double-roll hot-pressing laminating equipment;

[0068] Among them, the hot pressing temperature is 160~170 ℃; the hot pressing pressure is 20~22 bar.

[0069] In a fifth aspect, the present disclosure also provides an application of the polyethylene composite filter membrane of the present invention. Specifically, the polyethylene composite filter membrane manufactured by the present invention is used for filtering and treating liquid solutions. The liquid solution may be a polar chemical solution or an aqueous solution, including any one of experimental chemical samples, experimental water, medical raw materials, pharmaceutical solvents, injection injections, injection water, domestic water, industrial production solvents, industrial wastewater, surface water or seawater; domestic water is water used and drunk in daily life.

[0070] The technical solution of the present invention will be further described below in conjunction with specific examples. The linear low-density polyethylene (LLDPE) used in the following examples has a melt index of 22 g / 10min (190°C, 2.16 kg load, purchased from STERLITECH); the high-density polyethylene (HDPE) has a melt index of 7 g / 10min (190°C, 2.16 kg load, purchased from China Petrochemical Corporation); the polyethylene microporous filter membrane has a pore size of 0.45 μm and a thickness of 125 μm (purchased from STERLITECH).

[0071] Example 1

[0072] This example provides a method for manufacturing a polyethylene composite filtration membrane, the steps of which include:

[0073] S1: Linear low-density polyethylene, high-density polyethylene, and butyl suberic acid are mixed evenly, which is recorded as a melt precursor mixture; tetrafluorodichloroethane and difluorochloromethane are mixed evenly, which is recorded as a spinning solvent; the melt precursor mixture and the spinning solvent are added to the reactor and mixed evenly, preheated to 170°C, nitrogen is introduced and pressurized to 10 MPa, and finally heated to 210°C, and stirred in a closed state for 3 h until the temperature and pressure of the system are stable, which is a melt-solvent complex, wherein the melt-solvent complex contains 9wt% of linear low-density polyethylene, 7wt% of high-density polyethylene, 2wt% of butyl suberic acid, 70wt% of tetrafluorodichloroethane and 12wt% of difluorochloromethane with a mass fraction.

[0074] S2: The melt-solvent complex obtained in the previous step is added to a supercritical reactor, and supercritical carbon dioxide is injected under stirring to obtain a stable supercritical fluid; the supercritical fluid is instantaneously released into the atmosphere through a nozzle with an aperture of 1.5 μm and an air flow rate of 10,000 m / min. The ultrafine fiber bundles are stretched and opened by high-pressure air to form an ultrafine fiber web, which is then laid on a moving mesh curtain. The mesh is then cold pressed and hot rolled to obtain a non-woven membrane with a thickness of about 0.12 mm.

[0075] S3: Dissolve silver nitrate at a molar concentration of 0.3 mol / L in an ether aqueous solution with a volume concentration of 30vt% to obtain the modification solution. Immerse the non-woven fabric membrane obtained in the previous step in the modification solution for immersion treatment at a temperature of 105°C for 40 min. Take it out and drain it, then immerse it in an aqueous solution containing 0.5 mol / L sodium triacetoxyborohydride for 30 min, take it out and dry it in an oven at 80°C for 30 min to obtain an instantaneous pressure release spinning filter membrane support membrane.

[0076] S4: The instantaneous pressure-release spun filter membrane support membrane is laminated onto the polyethylene microporous filter membrane, and double-roll hot pressing and heat sealing are performed using a double-roll hot pressing composite device. The hot pressing temperature is controlled to be 160°C, and the hot pressing pressure is controlled to be 22 bar. The pore size of the polyethylene microporous filter membrane is 0.45 μm, and the thickness is 125 μm, to obtain a polyethylene composite filter membrane.

[0077] Example 2

[0078] This example provides a method for manufacturing a polyethylene composite filtration membrane, the steps of which include:

[0079] S1: Linear low-density polyethylene, high-density polyethylene, and butyl suberic acid are mixed evenly, which is recorded as a melt precursor mixture; tetrafluorodichloroethane and difluorochloromethane are mixed evenly, which is recorded as a spinning solvent; the melt precursor mixture and the spinning solvent are added to the reactor and mixed evenly, preheated to 190°C, nitrogen is introduced and pressurized to 12 MPa, and finally heated to 230°C, and stirred in a closed state for 3 h until the temperature and pressure of the system are stable, which is a melt-solvent complex, wherein the melt-solvent complex contains 10wt% of linear low-density polyethylene, 9wt% of high-density polyethylene, 1wt% of butyl suberic acid, 65wt% of tetrafluorodichloroethane and 15wt% of difluorochloromethane with a mass fraction.

[0080] S2: Add the melt-solvent complex obtained in the previous step into a supercritical reactor, and inject supercritical carbon dioxide under stirring to obtain a stable supercritical fluid; the supercritical fluid is instantly released into the atmosphere through a nozzle with an aperture of 1.5 μm and an air flow rate of 11,000 m / min. The ultrafine fiber bundles are stretched and opened by high-pressure air to form an ultrafine fiber web, which is then laid on a moving mesh curtain. The mesh is then cold pressed and hot rolled to obtain a non-woven membrane with a thickness of about 0.12 mm.

[0081] S3: Dissolve silver nitrate at a molar concentration of 0.4 mol / L in an ether aqueous solution with a volume concentration of 30vt% to obtain the modification solution. Immerse the non-woven fabric membrane obtained in the previous step in the modification solution for immersion treatment at a temperature of 110°C for 50 min. Take it out and drain it, then immerse it in an aqueous solution containing 0.8 mol / L sodium triacetoxyborohydride for 30 min, take it out and dry it in an oven at 90°C for 20 min to obtain an instantaneous pressure release spinning filter membrane support membrane.

[0082] S4: The instantaneous pressure-release spun filter membrane support membrane is laminated onto the polyethylene microporous filter membrane, and double-roll hot pressing and heat sealing are performed using a double-roll hot pressing composite device. The hot pressing temperature is controlled to be 160°C, and the hot pressing pressure is controlled to be 22 bar. The pore size of the polyethylene microporous filter membrane is 0.45 μm, and the thickness is 125 μm, to obtain a polyethylene composite filter membrane.

[0083] The polyethylene composite filtration membrane prepared in this example was characterized by SEM, and the results were Figure 1 shown.

[0084] according to Figure 1 It can be seen that the fibers in the lower layer of the polyethylene composite filter membrane are finer, and it is a non-woven membrane prepared by the instantaneous pressure release method, which has a higher specific surface area and good mechanical strength; the fibers in the upper layer are coarser and have larger pores, and it is a polyethylene microporous filter membrane, which has higher filtration efficiency and flux.

[0085] Example 3

[0086] This example provides a method for manufacturing a polyethylene composite filtration membrane, the steps of which include:

[0087] S1: Linear low-density polyethylene, high-density polyethylene, and butyl suberic acid are mixed evenly, which is recorded as a melt precursor mixture; tetrafluorodichloroethane and difluorochloromethane are mixed evenly, which is recorded as a spinning solvent; the melt precursor mixture and the spinning solvent are added to the reactor and mixed evenly, preheated to 180°C, nitrogen is introduced and pressurized to 11 MPa, and finally heated to 220°C, and stirred in a closed state for 3 h until the temperature and pressure of the system are stable, which is a melt-solvent complex, wherein the melt-solvent complex contains 8wt% of linear low-density polyethylene, 10wt% of high-density polyethylene, 1wt% of butyl suberic acid, 68wt% of tetrafluorodichloroethane and 13wt% of difluorochloromethane with a mass fraction.

[0088] S2: Add the melt-solvent complex obtained in the previous step into a supercritical reactor, and inject supercritical carbon dioxide under stirring to obtain a stable supercritical fluid; the supercritical fluid is instantly released into the atmosphere through a nozzle with an aperture of 1.5 μm and an air flow rate of 11,000 m / min. The ultrafine fiber bundles are stretched and opened by high-pressure air to form an ultrafine fiber web, which is then laid on a moving mesh curtain. The mesh is then cold pressed and hot rolled to obtain a non-woven membrane with a thickness of about 0.12 mm.

[0089] S3: Dissolve silver nitrate at a molar concentration of 0.5 mol / L in an ether aqueous solution with a volume concentration of 40vt% to obtain the modification solution. Immerse the non-woven fabric membrane obtained in the previous step in the modification solution for immersion treatment at a temperature of 100°C for 60 min. Take it out and drain it, then immerse it in an aqueous solution containing 0.5 mol / L sodium triacetoxyborohydride for 60 min, take it out and dry it in an oven at 90°C for 40 min to obtain an instantaneous pressure release spinning filter membrane support membrane.

[0090] S4: The instantaneous pressure-release spun filter membrane support membrane is laminated onto the polyethylene microporous filter membrane, and double-roll hot pressing and heat sealing are performed using a double-roll hot pressing composite device. The hot pressing temperature is controlled to be 160°C, and the hot pressing pressure is controlled to be 21 bar. The pore size of the polyethylene microporous filter membrane is 0.45 μm, and the thickness is 125 μm, to obtain a polyethylene composite filter membrane.

[0091] Example 4

[0092] The difference between this example and Example 2 is that the contents of components in the melt-solvent composite are different. The melt-solvent composite specifically contains 5 wt% of linear low-density polyethylene, 14 wt% of high-density polyethylene, 1 wt% of butyl suberic acid, 65 wt% of tetrafluorodichloroethane and 15 wt% of difluorochloromethane.

[0093] Example 5

[0094] The difference between this example and Example 2 is that the contents of components in the melt-solvent composite are different. The melt-solvent composite specifically contains 13 wt% of linear low-density polyethylene, 6 wt% of high-density polyethylene, 1 wt% of butyl suberic acid, 65 wt% of tetrafluorodichloroethane and 15 wt% of difluorochloromethane.

[0095] Example 6

[0096] The difference between this example and Example 2 is that the contents of components in the melt-solvent composite are different. The melt-solvent composite specifically contains 10 wt% of linear low-density polyethylene, 9 wt% of high-density polyethylene, 0.5 wt% of butyl suberic acid, 65.5 wt% of tetrafluorodichloroethane and 15 wt% of difluorochloromethane.

[0097] Example 7

[0098] The difference between this example and Example 2 is that the hot pressing and heat sealing parameter settings in step S4 are different. The specific hot pressing parameter settings are: controlling the hot pressing temperature to 170° C. and the hot pressing pressure to 20 bar to obtain a polyethylene composite filtration membrane.

[0099] Comparative Example 1

[0100] The difference between this comparative example and Example 2 is that butyl suberic acid is omitted in the melt-solvent composite composition, and the melt-solvent composite specifically comprises 10 wt% of linear low-density polyethylene, 9 wt% of high-density polyethylene, 0.5 wt% of butyl suberic acid, 65.5 wt% of tetrafluorodichloroethane and 15 wt% of difluorochloromethane.

[0101] Comparative Example 2

[0102] The difference between this comparative example and Example 2 is that the high-density polyethylene is omitted from the melt-solvent composite component, and the melt-solvent composite specifically comprises 19 wt% of linear low-density polyethylene, 1 wt% of butyl suberic acid, 65 wt% of tetrafluorodichloroethane and 15 wt% of difluorochloromethane.

[0103] Comparative Example 3

[0104] The difference between this comparative example and Example 2 is that the linear low-density polyethylene is omitted from the melt-solvent composite composition. The specific melt-solvent composite contains 19 wt % of high-density polyethylene, 1 wt % of butyl suberic acid, 65 wt % of tetrafluorodichloroethane and 15 wt % of difluorochloromethane.

[0105] Comparative Example 4

[0106] The difference between this comparative example and Example 2 is that the linear low-density polyethylene in the melt-solvent composite is greater than 14 wt% and the high-density polyethylene is less than 5 wt%. The melt-solvent composite specifically comprises 15 wt% of linear low-density polyethylene, 4 wt% of high-density polyethylene, 1 wt% of butyl suberic acid, 65 wt% of tetrafluorodichloroethane and 15 wt% of difluorochloromethane.

[0107] Comparative Example 5

[0108] The difference between this comparative example and Example 2 is that the hot pressing and heat sealing parameter settings in step S4 are different. The specific hot pressing parameter settings are: controlling the hot pressing temperature to 150° C. and the hot pressing pressure to 20 bar to obtain a polyethylene composite filtration membrane.

[0109] Comparative Example 6

[0110] The difference between this comparative example and Example 2 is that the hot pressing and heat sealing parameter settings in step S4 are different. The specific hot pressing parameter settings are: controlling the hot pressing temperature to 180° C. and the hot pressing pressure to 20 bar to obtain a polyethylene composite filtration membrane.

[0111] Performance testing

[0112] (1) Hydrostatic pressure resistance: The polyethylene composite filtration membranes of the embodiments and comparative examples were subjected to a hydrostatic pressure test in accordance with GB / T 4744-2013, with a pressure increase rate of 5 kPa / min.

[0113] (2) Puncture resistance: The composite filtration membranes of the embodiments and comparative examples were subjected to puncture resistance tests according to GB / T 8809-2015.

[0114] (3) Antibacterial properties: Antibacterial tests were conducted according to GB / T 20944.3-2008 standard, Staphylococcus aureus and Escherichia coli were selected as test strains, and the 24-h antibacterial rates were obtained statistically;

[0115] (4) Pure water flux performance: The filter membrane was placed in a flux meter for pure water flux testing. The flux meter pressure was 0.2 MPa and the temperature was 25°C. The calculation formula for pure water flux was:

[0116] ;

[0117] J is the pure water flux, unit L / m 2 ·h; V is the volume of pure water passing through every 10 min, in L; M is the effective membrane area, in m 2 .

[0118] The test results of the above experiments are shown in Table 1.

[0119] Table 1: Performance test results of polyethylene composite filtration membrane

[0120]

[0121] According to Table 1, the instantaneous pressure-release spun filter membrane support membrane disclosed in the present invention can be used as a reinforcing skeleton to provide support by hot-pressing the polyethylene microporous filter membrane. Compared with the polyethylene microporous filter membrane of Comparative Example 1, the hydrostatic pressure resistance and puncture resistance of the polyethylene composite filter membrane prepared in Example 1 are improved by about 200-300%. The thickness of the instantaneous pressure-release spun filter membrane support membrane is equivalent to that of the polyethylene filter membrane. Although the overall thickness after the composite is increased, compared with the self-composite of the polyethylene filter membrane of the same thickness, its hydrostatic pressure resistance and puncture resistance are improved by at least 50%, indicating that the relative requirements are met. Under the condition of the same mechanical strength, the polyethylene composite filter membrane of the present invention is thinner and lighter than the self-composite polyethylene filter membrane, and can meet the specific requirements of some precision instruments for thickness, weight and mechanical strength; at the same time, the support membrane for the instantaneous pressure release spinning filter membrane of the present invention can also provide a preliminary filtering effect, effectively intercept large particle impurities, improve filtering accuracy, and reduce clogging; the support membrane for the instantaneous pressure release spinning filter membrane has excellent hydrophilicity, which can improve the pure water flux of the polyethylene composite filter membrane, making it not much different from the polyethylene filter membrane, and the filtration efficiency is not greatly affected. In addition, when the hot-pressing glue-free method is used for compounding and applied to the filtration treatment of raw materials, medicinal solvents, water for injection, etc., it can avoid the reaction between glue and chemicals to affect the filtration effect. Specifically:

[0122] Compared with Comparative Example 1, in Example 2, butyl suberic acid with a carboxyl group at the tail end is added to the melt-solvent complex for preparing the instantaneous pressure-release spinning filter membrane support membrane, and a large number of carboxylic acid groups are introduced on the surface of the non-woven membrane. When the non-woven membrane is immersed in a modified solution containing silver nitrate, the oxidizing property of silver nitrate makes it easy to extract hydrogen atoms from the carboxylic acid to generate corresponding salts, and the silver ions are bonded with the carboxylic acid groups and stably grafted on the surface of the instantaneous non-woven membrane to provide antibacterial effects. The polyethylene microporous filter membrane of Comparative Example 1 has fewer carboxylic acid groups on the surface, and the content of silver ions grafted on the surface is low, so the antibacterial ability is limited. Moreover, butyl suberic acid also contains non-polar alkyl segments, which can be evenly dispersed in the non-polar spinning solution system. The carboxylic acid groups carried have high hydrophilicity, which helps to improve the hydrophilicity of the support membrane material for the instantaneous pressure-release spinning microfiltration membrane. When the aqueous solution is filtered, water molecules are more likely to pass through the membrane layer, which helps to improve the filtration efficiency. Therefore, the antibacterial performance and pure water flux of the polyethylene composite filtration membrane prepared in Example 2 are significantly higher than those in Comparative Example 1.

[0123] Comparing Examples 2 and 7 with Comparative Example 6, the hot pressing temperature of the instantaneous pressure-release spun filter membrane support membrane and the polyethylene filter membrane prepared in Examples 2 and 7 is 160-170 °C, which can ensure a relatively high pure water flux, while the hot pressing temperature of Comparative Example 6 is 180 °C. The higher temperature causes the micropores of the polyethylene filter membrane to be destroyed, affecting the filtration efficiency of the polyethylene composite filter membrane, and significantly reducing the pure water flux.

[0124] By comparing the schemes of Examples 2, 4-5 and Comparative Examples 2-4, it can be seen that the instantaneous pressure-release spun filter membrane support membrane prepared in Comparative Example 2 uses a single linear low-density polyethylene as a raw material, resulting in insufficient mechanical strength of the polyethylene composite filter membrane, and a significant decrease in hydrostatic pressure resistance and puncture resistance; the instantaneous pressure-release spun filter membrane support membrane prepared in Comparative Example 3 uses high-density polyethylene as a raw material, resulting in insufficient toughness of the polyethylene composite filter membrane, resulting in a puncture resistance far lower than that of Example 2, which cannot meet the requirements. Therefore, the present invention controls the content of the raw material components contained in the melt-solvent complex to be 6-14wt% of high-density polyethylene and 5-13wt% of linear low-density polyethylene, respectively, so that the skeleton support of the instantaneous pressure-release spun filter membrane support membrane can achieve a balance between strength and toughness, and meet a wider range of application needs.

[0125] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0126] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions recorded in the aforementioned embodiments may still be modified, or some or all of the technical features therein may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A method for manufacturing an instantaneous pressure-release spinning filter membrane support membrane, characterized in that: Contains steps: preparing a melt-solvent composite; Using the melt-solvent complex as spinning solution, a nonwoven membrane is prepared by instantaneous pressure release spinning technology; The non-woven fabric membrane is sequentially immersed in a modification solution containing silver nitrate for immersion modification, and immersed in an aqueous solution of sodium triacetoxyborohydride for immersion reduction, and then dried to obtain an instantaneous pressure release spinning filter membrane support membrane; Wherein, the raw material components of the melt-solvent complex are: (a) High-density polyethylene 6-14 wt%, with a melt index of 6-8 g / 10 min at 190 °C and 2.16 kg load; (b) 5-13 wt% linear low-density polyethylene, whose melt index at 190 °C and 2.16 kg load is 20-24 g / 10 min; (c) 0.5-2 wt% butyl suberic acid; (d) The spinning solvent is supplemented to 100 wt%.

2. The manufacturing method according to claim 1, characterized in that: The spinning solvent is selected from at least one of tetrafluorodichloroethane, difluoromonochloromethane, n-hexane, butane, pentene, heptane, octane, cyclohexane, dichloromethane, carbon tetrachloride, chloroform, chloromethane, chloroethane, trichlorofluoromethane, dichlorotrifluoroethane, pentafluoropropane, heptafluoropropane, perfluorohexane, perfluoroheptane, and octafluorocyclopentane.

3. The manufacturing method according to claim 1, characterized in that: The preparation of the melt-solvent complex comprises: The high-density polyethylene, linear low-density polyethylene, butyl suberic acid and spinning solvent are mixed, heated to 210-230°C in an inert atmosphere, pressurized to 10-12 MPa, and stirred until the temperature and pressure are stable to obtain a melt. - Solvent complex.

4. The manufacturing method according to claim 1, characterized in that: The method for preparing a nonwoven membrane by instantaneous pressure release spinning technology comprises: The spinning solution is added into a supercritical reactor with a nozzle aperture of 1 to 3 μm, and supercritical carbon dioxide is injected under stirring to obtain a stable supercritical fluid; The supercritical fluid is instantaneously released into the atmosphere at a jet flow rate of 10000-12000 m / min, stretched and opened by high-pressure air to form an ultrafine fiber web, and then cold pressed and hot rolled to obtain a non-woven fabric membrane.

5. The manufacturing method according to claim 1, characterized in that: The modified liquid containing silver nitrate comprises an ether aqueous solution and silver nitrate dissolved in the ether aqueous solution at a molar concentration of 0.3-0.5 mol / L, wherein the ether aqueous solution is a mixture of ether and water in a volume ratio of (3-4):(6-7); And, the molar concentration of the aqueous solution of sodium triacetoxyborohydride is 0.5-0.8 mol / L.

6. An instantaneous pressure release spinning filter membrane support membrane manufactured by the manufacturing method according to any one of claims 1 to 5.

7. A polyethylene composite filtration membrane, characterized in that: The composition comprises a polyethylene microporous filter membrane and a support membrane hot-pressed and composited on the polyethylene microporous filter membrane; Wherein, the support membrane comprises an instantaneous pressure-release spinning filter membrane support membrane produced by the manufacturing method according to any one of claims 1 to 4.

8. The polyethylene composite filtration membrane according to claim 7, characterized in that: The polyethylene composite filtration membrane at least comprises: (1) Resistance to hydrostatic pressure of 30,000 to 40,000 Pa; and (2) Maintain 4000~5000 L / m at 0.2 MPa pressure 2 ·h of pure water flux.

9. A method for producing the polyethylene composite filtration membrane according to claim 7 or 8, characterized in that: Contains steps: After the polyethylene microporous filter membrane is laminated to the surface to be laminated of the instantaneous pressure-release spinning filter membrane support membrane, heat-pressing and heat-sealing are performed by double-roll hot-pressing laminating equipment; Among them, the hot pressing temperature is 160~170 ℃; the hot pressing pressure is 20~22 bar.

10. Use of the polyethylene composite filtration membrane according to claim 8 or 9 in the filtration treatment of polar chemical solutions or aqueous solutions.

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