514 results about "Sulfone" patented technology

The invention discloses a crown ether grafted polyarylether sulfone ion separation membrane as well as a preparation method and application thereof, and belongs to the technical field of ion separation membranes, collaborative optimization is realized through crown ether accurate grafting and ultrathin ordered membrane formation: a main chain of polyarylether sulfone is grafted with 4 '-aminobenzo-12-crown-4 to form an inherent channel adapted to Li, and the specific surface area of the main chain is increased; the ultrathin film is prepared by a water surface spreading method, and the ion transmission path is shortened. Finally, in a LiCl / MgCl system, Liion flux has high selectivity, high permeation-high selectivity cooperation is preliminarily realized, the chemical synthesis step can be amplified to a kilogram level, and after a DPAES-g-CE / dichloromethane solution is dropwise added to the water surface, the DPAES-g-CE / dichloromethane solution is rapidly spread to form a film without precise equipment; the raw materials are industrial-grade monomers and have no toxic residues, the membrane can be recycled and reused through dichloromethane, the equipment cost is reduced by about 90%, and industrialization is easy; the main chain of the polyaryl ether sulfone is high in rigidity and resistant to high temperature and chemical corrosion; crown ether grafting avoids molecular chain agglomeration, and the swelling rate is far lower than that of a traditional sulfonated membrane.

The invention belongs to the technical field of membrane separation, and particularly relates to a method for preparing a high-flux hollow fiber nanofiltration membrane based on interfacial polymerization, the obtained membrane and application. The method comprises the following steps: firstly, carrying out pre-adsorption treatment on a polyethersulfone hollow fiber ultrafiltration base membrane through a polyethyleneimine aqueous solution to form a reactive anchoring layer; then sequentially dipping in an aqueous phase solution containing piperazine, sodium phytate and nanoscale cellulose whiskers and an organic phase solution containing trimesoyl chloride and 5-isocyanate isopeptide acyl chloride for interfacial polymerization; and finally, carrying out heat treatment on the obtained primary composite membrane, and completing a gas-phase cross-linking reaction in a glutaraldehyde steam atmosphere. According to the method, the hollow fiber nanofiltration membrane with high flux, high selectivity, excellent chlorine resistance and pollution resistance is successfully prepared through a multi-stage strengthening process, and the hollow fiber nanofiltration membrane is suitable for the fields of drinking water purification, industrial wastewater reuse, material separation and the like.

The present invention relates to a sulfone compound-based electrolyte and a secondary battery including the sulfone compound-based electrolyte. The secondary battery according to the present invention can suppress gas generation in high temperature or thermal runaway environments or generate non-flammable gas to reduce the risk of ignition or explosion.

The invention relates to the technical field of polyamide nanofiltration membranes, in particular to an acid and alkali resistant high-strength nanofiltration membrane and a preparation method thereof. The problem that the strength and the acid and alkali resistance of a polyamide nanofiltration membrane in the prior art cannot be considered at the same time is solved. The base membrane material of the polyamide nanofiltration membrane is modified polyethersulfone and is obtained by chemically bonding a carbon nanotube subjected to double surface modification by titanium dioxide sol-gel and a KH550 coupling agent in a polyester non-woven fabric, and the modulus of the material is improved by utilizing an inorganic-organic hybrid network; the functional layer of the polyamide nanofiltration membrane is made of modified polyamide, and the modified polyamide functional layer is formed by forming a polyamide matrix through polymerization reaction of 2, 2 '-disulfonic acid-4, 4'-diaminobiphenyl, piperazine and trimesoyl chloride and introducing 4-amino-2, 2, 6, 7-tetramethyl-1, 3-pentanediol at the same time. And the chemical resistance is improved by a free radical capturing group generated by 2, 2, 6, 6-tetramethylpiperidine and octa-isobutyl cage type silsesquioxane.

The invention discloses a preparation process of polyether-ether-ketone, and relates to the technical field of preparation of inorganic compounds. The preparation process comprises the following steps: reacting 4, 4 '-difluorobenzophenone, sodium carbonate and hydroquinone to generate polyether-ether-ketone, taking a polyaryletherketone block oligomer as an end-capping reagent, reacting 4, 4'-difluorobenzophenone with 4, 4 '-dimercaptodiphenyl sulfone, and then reacting with pentaerythritol phosphate to obtain the polyaryletherketone block oligomer. The thioester bond reversibly breaks at the polymerization temperature, exposed active sulfenyl reacts with hydroxyl at the tail end of the polyether-ether-ketone to form a more stable covalent bond, volatilization of the end-capping reagent is avoided, meanwhile, the initial decomposition temperature of the end-capped polyether-ether-ketone is increased, and the stability of the end-capping reagent is improved. The polyether-ether-ketone generated in the polyether-ether-ketone resin product is subjected to treatment procedures of crushing, organic solvent extraction, water washing, filtering, drying and the like, so that the product polyether-ether-ketone is obtained, less three wastes are generated, the solvent can be recycled, the atom economy is relatively high, and the preparation process of comprehensive utilization of resources is realized.

The invention relates to the technical field of batteries, in particular to molecular cage electrolyte for a sodium ion battery, a preparation method of the molecular cage electrolyte and the battery. The preparation method comprises the following steps: mixing a metal organic polyhedron with a safe solvent, and completing cage-entering coordination to obtain a prefabricated solution; mixing the pre-prepared solution with an electrolyte salt solution to prepare an electrolyte; wherein the metal organic polyhedron comprises at least one of a copper-based cage, a uranium-based cage, a zirconium-based cage, a chromium-based cage, a zinc-based cage, a magnesium-based cage, a rhodium-based cage and a lanthanum-based cage; the safe solvent comprises at least one of a phosphate ester solvent, a phosphite ester solvent, a sulfone solvent, a fluorosulfone solvent, a fluorophosphate ester solvent and a phosphazene solvent; the electrolyte salt solution comprises an electrolyte salt, an organic solvent and a functional additive. According to the electrolyte prepared by the preparation method, the thermal safety performance of the battery can be improved, and the electrochemical performance of the battery can also be improved.

The invention provides a dyeable high-temperature-resistant modified meta-position aramid fiber and a preparation method thereof. The modified meta-aramid fiber is mainly prepared from a spinning solution prepared from m-phenylenediamine, methyl 3, 5-diaminobenzoate, 3, 3 '-diaminodiphenyl sulfone and an isophthaloyl dichloride copolymer through dry spinning, and the dye uptake of a disperse dye is not lower than 85%; the thermal decomposition temperature is not less than 400 DEG C. The preparation method comprises the following steps. S1, fully continuous polymerization; s2, continuously neutralizing and conveying; s3, direct spinning; and S4, fiber forming and post-treatment. The method has the advantages that (1) the quality difference between batches in the traditional intermittent method is eliminated, and the uniformity and stability of the product performance are realized; and the preparation process is compact, the production efficiency is high and the energy consumption is low. And (2) the dyeing performance of the prepared fiber is obviously improved, the inherent high-temperature-resistant characteristic of the aramid fiber is maintained, and the mechanical property is excellent. And (3) the application range of the meta-position aramid fiber is expanded.

The invention relates to the field of polymer functional membrane materials, and particularly provides a composite sulfonated polyarylene ether nitrile sulfone proton exchange membrane and a preparation method thereof. Sulfonated poly (arylene ether nitrile sulfone) is synthesized through nucleophilic substitution reaction, and the sulfonated poly (arylene ether nitrile sulfone) and sulfonated cobalt phthalocyanine are subjected to blending and casting to form a membrane, so that the provided composite sulfonated poly (arylene ether nitrile sulfone) proton exchange resin contains a sulfonic acid structural unit, a sulfone structural unit, a polar cyano group and a phthalocyanine structural unit; the problem that an existing proton exchange membrane is low in sulfonation degree and proton conductivity can be solved, and the proton exchange membrane has the advantages of being high in structural stability, good in mechanical property, excellent in thermal stability and high in safety. The introduction of sulfonated cobalt phthalocyanine can effectively improve the internal structure of the sulfonated polyarylene ether nitrile sulfone proton exchange membrane, promote the conduction rate of water molecules in the membrane, and further improve the proton conductivity of the sulfonated polyarylene ether nitrile sulfone proton exchange membrane. In addition, the manufacturing process is green and simple, the compounding cost is low, and the application prospect is very wide.

The invention discloses N-alkylated / sulfonated benzimidazole polyaryletherketone / polyaryletherketone sulfone with controllable grafting density as well as a preparation method and application of the N-alkylated / sulfonated benzimidazole polyaryletherketone / polyaryletherketone sulfone. The preparation method comprises the following steps: firstly, introducing a protecting group on a phenolic hydroxyl group of a bisphenol monomer containing a benzimidazole structure, then carrying out nucleophilic substitution reaction on alkyl halide / alkyl halide sulfonic acid and-NH, and then removing the protecting group to obtain an N-alkylated / sulfonated benzimidazole functionalized bisphenol monomer; copolymerizing the monomer, a bisphenol monomer and a difluoro monomer to obtain a polymer; alkyl or alkyl sulfonic acid is introduced to a benzimidazole ring, so that-NH bonds are passivated, a steric hindrance effect is formed, and gelation of the polymer under a high polymerization degree is avoided; by adjusting the molar ratio of the monomers, the retention stability of the functional groups can be effectively controlled, and compared with the traditional grafting on the polymer, the non-regulation of functionalization and the gelation of the polymer are effectively avoided.

The application provides a virus-removing polyether sulfone porous membrane and a preparation method thereof. The virus-removing polyether sulfone porous membrane comprises, in sequence along a thickness direction, an outer layer region and an inner layer region, wherein the average pore size of the outer layer region is 10-20 nm, the thickness of the outer layer region is 20-50 microns, the average pore size of the inner layer region is 5-10 microns, and the thickness of the inner layer region is 60-150 microns; and the virus-removing polyether sulfone porous membrane is prepared by a method comprising at least the following process: taking polyether sulfone as a raw material, and obtaining the virus-removing polyether sulfone porous membrane under the action of a water-soluble diluent and a hydrophilic additive; wherein the water-soluble diluent comprises ethylene carbonate and polyethylene glycol. The virus-removing polyether sulfone porous membrane has a high virus removal rate and a high protein permeation rate.

The application relates to the technical field of materials, and discloses a kind of corrosion-resistant coated steel pipes and preparation method thereof, the coated steel pipe includes steel pipe body and is coated in functional coating, functional coating is formed by coating functional coating on the surface of steel pipe body, and is cured, functional coating is formed by mixing with epoxy resin as film-forming material and glass flake modified material as additive, glass flake modified material is modified by macromolecular material with benzene sulfone-fluorosilane alternate connection structure on the surface of glass flake, due to the benzene sulfone structure in the structure of macromolecular material can produce pi-pi conjugation between epoxy resin matrix, the compatibility of glass flake and epoxy resin is improved, the strength and corrosion resistance of coating are enhanced, macromolecular material can form highly hydrophobic layer on the surface of coating, construct the synergistic effect of "interface strengthening-network crosslinking-corrosion prevention", greatly enhance the corrosion resistance of coating.

The invention relates to the technical field of secondary batteries, and discloses a battery, the bottom layer of a positive plate is rich in a ternary material, the surface layer of the positive plate is rich in lithium cobalt oxide, meanwhile, lithium cobalt oxide particles A exist in a transition region, a specific minimum distance a is maintained between the lithium cobalt oxide particles A and lithium cobalt oxide particles B in a second region, an electrolyte contains a specific content of 1, 3-propane sultone (the content is b wt%), and the content of 1, 3-propane sultone is controlled. The content b of the 1, 3-propane sultone and the content a meet the condition that b / a is more than or equal to 0.02 and less than or equal to 2.9. By optimizing the structural design of the positive electrode active layer and matching specific electrolyte composition, the transmission behavior of lithium ions in the thickness direction of the active layer and the interface electrochemical environment are synergistically improved, and the cycle life of the battery under the conditions of high energy density, high voltage and high temperature is prolonged.

The application discloses a filter core material and a preparation method thereof, and belongs to the technical field of water purification filter cores. The filter core material comprises the following components in percentage by mass: a honeycomb support matrix: 15-60%; a filter substrate: 30-40%; and a coating substrate: 0-50%. The filter core material and the preparation method thereof maintain a stable support structure during the preparation of a gamma-Al2O3 / BN composite ceramic layer through polypropylene and cellulose nanofiber. The filter substrate is obtained through gradient low-temperature sintering, effectively removes small particles and pollutants in water, and has excellent filtering performance. The active carbon fiber and polyether sulfone are coated on the filter substrate through electrospinning, which ensures good filtering performance and water permeability, improves the wear resistance and compressive strength of the filter core, and removes the honeycomb support matrix through high-temperature combustion, further improves the water permeability, and the active carbon fiber is physically activated during the combustion process, further improving the adsorption capacity.

The application belongs to the field of high dielectric constant (ε r ), low dielectric loss (tan delta) composite dielectric material, and particularly relates to a preparation method of a modified polyether sulfone / polyether imide polymer alloy. g Polymer polyether imide is blended, the mixture is added into DMAc at a solid content of 15%-20%, is stirred and dissolved at 80 DEG C, then a thin film is prepared on a glass plate by using a scraping coating method, finally the glass plate is transferred to a vacuum oven, is kept at 55 DEG C overnight, is kept at 100 DEG C for 3-5 hours, and is cured at 180 DEG C for 3-5 hours, thereby a blended film is prepared, wherein the mass fraction of the modified polyether sulfone in the mixture is 1wt%-30wt%. The modified polyaryl ether sulfone polymer segment with a side chain branched large dipole moment polar group is used as an organic filler, a small amount of addition can greatly reduce the dielectric loss, the operation is simple, the spectrum is good, and the influence on T g is very small, and the dispersion and interface problems of inorganic fillers are avoided.

The application provides a boron nitride nanosheet-doped polyamide composite nanofiltration membrane and a preparation method. The method uniformly disperses boron nitride nanosheets in deionized water, and then uniformly mixes the boron nitride nanosheets with a piperazine aqueous solution. The mass ratio of the boron nitride nanosheets to the piperazine is (5.01-20.04):(60-200), and a mixed solution is obtained. The mixed solution is vacuum filtered on a polyether sulfone ultrafiltration membrane, and the polyether sulfone ultrafiltration membrane is left with a mixture of uniformly dispersed boron nitride nanosheets and piperazine. A triformylchloride solution is poured on the mixture of the boron nitride nanosheets and the piperazine. The mass ratio of the boron nitride nanosheets to the triformylchloride is (5.01-20.04):100. The triformylchloride and the piperazine are interfacially polymerized on the surface of the polyether sulfone ultrafiltration membrane. The solvent of the triformylchloride solution is then poured off. After drying, a boron nitride nanosheet-doped polyamide composite nanofiltration membrane is obtained, and the permeation flux and the antifouling property of the polyamide nanofiltration membrane are improved.

A macroporous cation exchange resin and its preparation and application method are disclosed. The method involves dispersing polystyrene-divinylbenzene microspheres in dichloroethane to obtain a microsphere suspension. A sulfonating agent, a mixture of fuming sulfuric acid and chlorosulfonic acid, is then slowly added dropwise under cooling and stirring conditions. After the addition is complete, heating is initiated to trigger a polysulfonation reaction. Once the reaction is complete, the reaction mixture is slowly poured into ice water and continuously stirred and diluted until the solution pH reaches 2.5. The solution is then filtered, washed, and dried to obtain a solid resin. This invention simultaneously introduces a matched number of sulfonic acid groups and sulfone groups onto the polystyrene-divinylbenzene backbone. Utilizing the electron-withdrawing effect of the sulfone groups and the rigid framework they form, the stability of the C-H and C-S bonds in the resin is enhanced. This solves the problems of resin structure damage, rapid decline in separation performance, and significantly shortened service life associated with existing cation exchange resins used in treating chromium plating aging solutions.

The present invention relates to a novel haloalkyl sulfonanilide compound or a salt thereof, a herbicide composition containing the compound or salt thereof, a method of weed control, including the step of applying the herbicide composition, and a method of producing the compound.

The invention discloses a secondary battery, and belongs to the technical field of batteries, the secondary battery is characterized in that a ternary material is used as a positive electrode active material, and tris (dimethyl vinyl silicon) phosphate and 1, 3-propane sultone are introduced into an electrolyte to serve as functional additives, so that the secondary battery is obtained. And meanwhile, the content of the two in the electrolyte and the adhesive force relationship of the diaphragm are regulated and controlled, so that the side reaction between the pole piece active material in the secondary battery and the electrolyte can be effectively inhibited, the gas production probability is reduced, and the ideal ion / electron transmission efficiency and cycle performance are finally realized.

The invention discloses a passive sampling device and method for specifically enriching quinolones and tetracyclines antibiotics, and relates to water body detection. Firstly, a hydrogel thin film prepared from ZIF-C as an adsorbent is adopted as a binding film, ZIF-C particles are uniformly dispersed on the surface of the binding film, specific adsorption of quinolones and tetracyclines antibiotics can be achieved, then the binding film, a diffusion film and a polyether sulfone filtering film are sequentially stacked to be assembled into an o-DGT device, o-DGT is put into a water body, and through diffusion and adsorption, the specific adsorption of the quinolones and tetracyclines antibiotics can be achieved. The method realizes the extraction and detection of quinolone and tetracycline antibiotics by the DGT technology.

Provided is a coating composition which has excellent coating properties and which forms a coating film that has good water vapor resistance and corrosion resistance. A coating composition comprising an aqueous dispersion containing a water-soluble polyamideimide resin (P), a polyethersulfone resin (Q), and a fluorine-containing polymer (R) containing a non-melt-processable fluorine-containing polymer (S) and a melt-processable perfluoropolymer (T) having a melting point of 200-350 DEG C, the mass ratio of the water-soluble polyamideimide resin (P) to the polyethersulfone resin (Q) is 10 / 90 to 40 / 60.

The present invention provides an industrially desirable production method for a sulfone derivative that is useful as a herbicide, and an intermediate thereof.

This invention relates to the field of organic synthetic chemistry, specifically to a polysubstituted furan compound and its synthetic method, wherein the method comprises... β Using ketone sulfones and olefins as starting materials, polysubstituted furans are synthesized via a [3+2] cycloaddition reaction in the presence of a copper catalyst and an oxidant. This invention employs cuprous bromide as the catalyst and di-tert-butyl peroxide (DTBP) as the oxidant, reacting in dimethyl sulfoxide solvent at 100°C–130°C for 6–24 h. This method offers advantages such as high atom and step economy, broad substrate applicability, good functional group tolerance, excellent position selectivity, and high yield, with a maximum yield reaching 84%. It is suitable for large-scale synthesis and provides a new strategy for the synthesis of furans in medicinal chemistry and materials science.

The invention discloses a charged hollow fiber loose nanofiltration membrane as well as a preparation method and application thereof. The hollow fiber nanofiltration membrane comprises a supporting layer and a charged separation layer, and the charged separation layer is attached to the inner surface of the hollow fiber supporting layer and is co-extruded and molded by adopting a double-layer spinneret plate; the charge separation layer comprises a charge polymer and a matrix polymer, and a positively charged polymer or a negatively charged polymer is selected according to an entrapment dye; the negatively charged separation layer further comprises hydroxylated polyether sulfone; the charged hollow fiber loose nanofiltration membrane is prepared by preparing an inner-layer membrane casting solution and an outer-layer membrane casting solution, carrying out co-extrusion molding through a double-layer spinneret plate, carrying out phase inversion membrane formation and then carrying out post-treatment. During application, corresponding charged nanofiltration membranes can be selected according to the electrical properties of dyes in sewage, efficient selective interception of different charged dyes is achieved, meanwhile, high transmittance is achieved for inorganic salt, the technological process of a one-step continuous forming process is simplified, the production efficiency is high, the method can be compatible with an existing hollow fiber membrane production line, and industrialization is easy to achieve.

The invention discloses a treatment system for synergistically removing odor substances and a new pollutant PFAS in water and a treatment method thereof. The treatment system comprises a pre-oxidation unit, an algae removal, adsorption and clarification unit, a membrane separation and concentration unit and a destruction unit which are connected in sequence. The pre-oxidation unit is provided with an oxidation pond with a transverse reciprocating dynamic aeration assembly, so that the ozone mass transfer efficiency is improved. The algae removal, adsorption and clarification unit enables a suspended carbon mud bed to periodically expand and contract through a pulse generator so as to strengthen adsorption. The membrane separation and concentration unit adopts a modified polyether sulfone conical-end filtering membrane and is matched with an online cleaning mechanism, so that PFAS is efficiently intercepted, and secondary pollution is avoided. The destroying unit is used for carrying out synergetic high-temperature incineration on the membrane separation concentrated water and the waste carbon mud, and PFAS is thoroughly decomposed at the temperature higher than or equal to 900 DEG C; by optimizing ozone aeration, pulse adsorption, fluorine-free membrane separation and collaborative incineration, efficient collaborative removal of odor substances and new pollutant PFAS and harmless treatment of waste are achieved, the system integration degree is high, the treatment effect is good, and the risk of secondary pollution is avoided.

The application discloses a polyarylether sulfone composite diaphragm, a preparation method thereof, an electrochemical device and an electric device. The polyarylether sulfone composite diaphragm comprises a base film and a composite coating arranged on at least one side of the base film, and the composite coating comprises polyarylether sulfone, a binder and an alkali metal ion compound. The polyarylether sulfone composite diaphragm of the embodiment of the application can improve the thermal dimensional stability of the polyolefin diaphragm by arranging the composite coating comprising polyarylether sulfone, a binder and a lithium-containing compound on at least one side of the base film, improve the affinity of the polyarylether sulfone composite diaphragm and the electrolyte by using the amorphous structure and the gel state of the electrolyte, and improve the cation transport capacity of the composite coating by using the alkali metal ion compound, thereby improving the ion transference number and the ionic conductivity.

The present application relates to a kind of water-based paint for leather surface waterproof, belong to coating technical field.The water-based paint is made of the following components: 80 parts polyether sulfone modified polyurethane-acrylate composite resin dispersion, 5 parts crosslinking agent polycarbodiimide, 10 parts anti-adhesive polydimethylsiloxane, 10 parts cosolvent dipropylene glycol methyl ether, 10 parts nano reinforcing material, 1.5 parts amino-terminated hyperbranched polyamide.Core resin dispersion is prepared by grafting onto polyurethane-acrylate skeleton through sulfonated polyether sulfone chemistry.The present application is prepared by unique resin chemical modification and nanocomposite technology, so that the obtained coating has excellent waterproofness, high adhesion, good mechanical strength and anti-aging property, especially suitable for high requirements such as automotive interior, furniture and other leather surface treatment, while meeting environmental protection requirements.

This invention relates to the field of membrane preparation technology and discloses a method for preparing a bipolar membrane with the same main chain for both anion and cation exchange layers. Using sulfonated polyarylene ether sulfone as the cation exchange layer and Br-3C-IM imidazole salt-functionalized polyarylene ether sulfone as the anion exchange layer improves the compatibility between the anion and cation layers, thereby enhancing the mechanical and chemical stability of the bipolar membrane. Using a bifunctionalized MOF as the intermediate interface layer, the –SO3H and –NH2 groups in the MOF interact with the anion and cation layers to form intramolecular hydrogen bonds, resulting in strong adhesion between the anion and cation layers and the intermediate interface layer, which helps prevent bipolar membrane delamination. Furthermore, the bifunctionalized MOF contains two catalytic sites acting as inorganic metal ions and organic ligands, promoting the water dissociation rate through a protonation-deprotonation mechanism.

The invention relates to a preparation method of 3-(piperazine-1-yl) propane-1-sulfonic acid, and relates to the technical field of organic chemical synthesis. The preparation method of the 3-(piperazine-1-yl) propane-1-sulfonic acid comprises the following steps: feeding and stirring, dropwise adding and mixing, carrying out temperature-controlled reaction, and purifying and drying. The cosolvent activates amino groups and inhibits side reactions, complete reaction of the substrate 1, 3-propane sultone is ensured through excessive piperazine, generation of by-products is reduced in the dropwise adding process, the temperature control reaction equilibrium rate is achieved, purification treatment is conducted through the pulping agent in the final purification and drying stage, reaction impurities are effectively removed, and it is finally guaranteed that the product purity meets the pharmaceutical grade requirement; the whole technological process is simple, the production period is shortened, and labor and time cost is reduced.

The invention belongs to the technical field of polyethersulfone, and particularly discloses a polyethersulfone microfiltration membrane with an integrally-formed double-layer structure and a preparation method of the polyethersulfone microfiltration membrane. The polyethersulfone microfiltration membrane is prepared from a single solution coating through an upper and lower layer dual induction process, and the cross section of the membrane is in a highly asymmetric form with a double-layer structure on the integrity; the upper layer is of a coarse-branch continuous macroporous structure and can accommodate more intercepted particles, so that the service life of the filter membrane is prolonged; the lower layer is of a fine branched continuous small hole structure, so that interception of particles can be ensured, and the filtering quality is improved; the upper layer and the lower layer are communicated in aperture, the structural cohesion is good, and no fracture phenomenon occurs; the thickness ratio of the upper layer to the lower layer is 2: (2.5-3.5); the preparation technology is simple and controllable in process, easy to implement, low in equipment requirement and suitable for batch production.