A graphene filter material and its preparation method

Abstract

This invention relates to the field of filter material technology and discloses a graphene filter material and its preparation method. The preparation method of the graphene filter material includes the following steps: (1) mixing graphene and a polymer carrier to obtain a mixture; (2) melting and extruding the mixture to obtain a melt, spinning the melt to obtain matrix fibers, and simultaneously intercalating graphene fibers into the matrix fibers to obtain the graphene filter material; wherein the intercalation speed is 2-50 m / s and the intercalation distance is 5-20 cm. This invention achieves uniform dispersion and embedding of graphene fibers in the matrix fibers by precisely controlling the intercalation speed and distance, avoiding local aggregation of graphene fibers, thereby increasing the graphene content in the filter product. The prepared graphene filter material has excellent filtration performance as well as antibacterial, antiviral and formaldehyde removal properties.

Description

Technical Field

[0001] This invention relates to the field of filter materials technology, and in particular to a graphene filter material and its preparation method. Background Technology

[0002] Graphene and its derivatives, as novel two-dimensional multifunctional nanomaterials, have demonstrated unique advantages in biomedicine, environmental engineering, and smart building materials due to their broad-spectrum antimicrobial properties and high-efficiency air purification capabilities. Their air pollutant retention efficiency stems from a multi-level dynamic filtration system formed by a three-dimensional nano-sieve structure and surface chemical adsorption sites. The core mechanism for combating pathogens is achieved through a four-dimensional synergistic effect of physical cutting, component exfoliation, spatial confinement, and oxidative damage, overcoming the limitations of traditional filter materials in antibacterial, antiviral, and formaldehyde removal applications. However, graphene has a typical sheet-like structure and small scale. While commonly used methods such as ultrasonic and high-pressure homogenization can disperse graphene, they are time-consuming, inefficient, and prone to damaging its internal structure, affecting filtration performance. Furthermore, the low functional group content of graphene molecules and the poor compatibility between pure graphene and polymers further complicate dispersion. Because graphene is difficult to disperse uniformly, even increasing the amount of graphene added to filter products cannot achieve a breakthrough in filtration performance. Therefore, how to improve the dispersion performance of graphene in filter materials to achieve a breakthrough in graphene content and thus enhance its filtration effect is an urgent problem to be solved. Summary of the Invention

[0003] In view of this, the present invention provides a graphene filter material and its preparation method to solve the problem that the poor dispersibility of existing graphene filter materials makes it difficult to further improve their filtration effect.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] On one hand, the present invention provides a method for preparing graphene filter material, comprising the following steps:

[0006] (1) Graphene and polymer support are mixed to obtain a mixture; in the mixture, the content of graphene is 1-30%;

[0007] (2) The mixture is melt-extruded to obtain a melt, the melt is spun to obtain a matrix fiber, and graphene fibers are intercalated in the matrix fiber to obtain a graphene filter material.

[0008] The intercalation speed is 2-50 m / s, and the intercalation distance is 5-20 cm.

[0009] Preferably, the mixture further includes additives, wherein the polymer carrier content is 55-98% and the additive content is 1-15% by mass percentage.

[0010] Preferably, the mixing temperature is <80°C.

[0011] Preferably, the graphene includes at least one of monolayer graphene, multilayer graphene, graphene oxide, carbon nanotubes, and graphene quantum dots.

[0012] Preferably, the polymer carrier comprises at least one selected from polypropylene, polyacrylonitrile, polylactic acid, polyamide, polyethylene, polyvinyl alcohol, and polyester.

[0013] Preferably, the additives include at least one of inorganic fillers, lubricants, compatibilizers, antioxidants, and ultraviolet absorbers.

[0014] Preferably, the melt extrusion process employs a six-zone gradient temperature control. From the feed to the discharge direction, the temperatures of the six zones are T1, T2, T3, T4, T5, and T6, where T5 > T4 > T3 > T2 > T1, and T5 > T6.

[0015] Preferably, T1 is 150-190℃, T2 is 160-200℃, T3 is 180-220℃, T4 is 200-230℃, T5 is 210-250℃, and T6 is 200-240℃.

[0016] Preferably, the spinning of the melt involves: conveying the melt to a meltblown die, then distributing it to the spinneret orifice for spinning to form a fine melt stream, which is then drawn by hot air to obtain matrix fibers.

[0017] Preferably, the melt is delivered to the meltblown die head by a metering pump, wherein the metering pump has a rotation speed of 10-30 rpm, a working pressure of 1-3 MPa, and a working temperature of 220-240℃;

[0018] Preferably, the temperature of the meltblown die head is 200-240℃.

[0019] Preferably, the diameter of the spinneret orifice is 0.2-0.4 mm.

[0020] Preferably, the distance of the spinneret is 150-400mm.

[0021] Preferably, the wind speed of the hot air is 300-600 m / s, and the temperature of the hot air is 200-300℃.

[0022] Preferably, the graphene fibers have a fineness of 1.5-9 dtex and a length of 10-80 mm.

[0023] Preferably, the graphene content in the graphene fiber is 1-15%.

[0024] Preferably, the graphene fiber is a synthetic fiber or a blended fiber, wherein the blended fiber is made by blending synthetic fibers and graphene, and the synthetic fiber includes at least one of polyester, acrylic, polypropylene, spandex and vinylon.

[0025] Preferably, the angle of the intercalation is 15-90°.

[0026] Preferably, the graphene is pretreated graphene, wherein the method for pretreating the graphene is as follows: mixing the graphene and an aqueous solution of a dispersant to obtain a premix, then subjecting the premix to ultrasonic treatment to obtain a dispersion, and finally purifying the dispersion by centrifugation and freeze-drying.

[0027] Preferably, the dispersant comprises at least one of polyvinyl alcohol, sodium polyacrylate, sodium dodecylbenzenesulfonate, polydopamine, and cellulose nanocrystals.

[0028] Preferably, the ultrasonic power is 200-1000W and the ultrasonic time is 0.5-4h.

[0029] On the other hand, the present invention also provides a graphene filter material prepared by the method described in any of the above-mentioned methods.

[0030] This invention provides a graphene filter material and its preparation method. Compared with the prior art, its advantages are as follows:

[0031] This invention involves melting and extruding a mixture of graphene and a polymer carrier, followed by spinning to obtain matrix fibers. Simultaneously, graphene fibers are intercalated into the matrix fibers to obtain graphene filter materials. By precisely controlling the graphene content, intercalation speed, and distance in the matrix fibers, uniform dispersion and embedding of graphene fibers in the matrix fibers are achieved, avoiding local aggregation of graphene fibers. This increases the graphene content in the filter products. The resulting graphene filter materials exhibit excellent filtration performance, as well as antibacterial, antiviral, and formaldehyde removal properties, making them suitable for high-end air filtration equipment, medical protective equipment, home / automotive interiors, and various other air filtration applications. Detailed Implementation

[0032] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments below are merely illustrative and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the later embodiments, conditions and methods known in the art can be used for processing.

[0033] In one aspect, the present invention provides a method for preparing a graphene filter material, comprising the following steps:

[0034] (1) Mix graphene and polymer carrier to obtain a mixture;

[0035] (2) The mixture is melt-extruded to obtain a melt, the melt is spun to obtain a matrix fiber, and graphene fiber is intercalated in the matrix fiber to obtain a graphene filter material.

[0036] In this invention, graphene and polymer support are first mixed to obtain a mixture.

[0037] In some embodiments of the present invention, the graphene includes at least one of single-layer graphene, multilayer graphene, graphene oxide, carbon nanotubes, and graphene quantum dots; the graphene content in the mixture is 1-30% by mass percentage, specifically 1%, 5%, 10%, 15%, 20%, 25%, and 30%, etc. If the graphene content is less than 1%, the filtration efficiency and antibacterial effect are not significantly improved, while a higher graphene content is prone to agglomeration, resulting in uneven dispersion in the melt, which in turn leads to lower strength of the matrix fiber, and at the same time, the filtration and antibacterial performance will also decrease.

[0038] In some embodiments of the present invention, the polymer carrier includes at least one selected from polypropylene, polyacrylonitrile, polylactic acid, polyamide, polyethylene, polyvinyl alcohol, and polyester; the content of the polymer carrier in the mixture is 55-98% by mass percentage, specifically 55%, 60%, 70%, 80%, 90%, and 98%, etc.

[0039] In some embodiments of the present invention, the additives include at least one of inorganic fillers, lubricants, compatibilizers, antioxidants, and ultraviolet absorbers; the content of the additives in the mixture is 1-15% by mass percentage.

[0040] Specifically, in the mixture, the content of the inorganic filler is 0.6-10%, specifically 0.6%, 1%, 5%, and 10%, etc., and the inorganic filler includes at least one of talc, heavy calcium carbonate powder, and wollastonite; the content of the lubricant is 0.1-1%, specifically 0.1%, 0.5%, and 1%, etc., and the lubricant includes at least one of mineral oil, silicone oil, and ester oil; the content of the compatibilizer is 0.1-1%, specifically 0.1%, 0.5%, and 1%, etc., and the compatibilizer includes maleic anhydride-grafted polypropylene (pp-g-MAH), maleic anhydride-grafted acrylonitrile-butadiene-styrene copolymer (ABS-g-MAH), and glycidyl methacrylate-grafted polylactic acid (PP-g-MAH). The antioxidant content is 0.1-2%, specifically 0.1%, 0.5%, 1%, and 2%, etc., and the antioxidant includes at least one of antioxidant B215, butylated hydroxytoluene (BHT), and dilauryl thiodipropionate (DLTDP); the ultraviolet absorber content is 0.1-1%, specifically 0.1%, 0.5%, and 1%, etc., and the ultraviolet absorber includes at least one of 2-hydroxy-4-n-octyloxybenzophenone (UV-531), 2-(2'-hydroxy-3',5'-bis(α,α-dimethylbenzyl)phenyl)benzotriazole (UV-234), and 2-hydroxy-4-n-octyloxybenzophenone (Chimassorb 81).

[0041] In some embodiments of the present invention, the specific steps for mixing graphene, polymer carrier, and additives are as follows: first, premixing graphene and additives (excluding filler) and then stirring and mixing with the polymer carrier to obtain a premix; then adding filler to the premix and stirring to disperse, to obtain a mixture. Compared to mixing graphene, additives, and polymer carrier simultaneously, premixing graphene and additives before adding them to the polymer carrier results in more uniform dispersion of graphene fibers and an increased graphene content in the final graphene filter material, thereby further improving its filtration effect. The stirring speed during the mixing process is 500-800 rpm, specifically 500 rpm, 600 rpm, 700 rpm, and 800 rpm, and the stirring time is 1-10 min, specifically 1 min, 5 min, and 10 min, etc.; the stirring speed during the dispersion process is 1500-2500 rpm, specifically 1500 rpm, 2000 rpm, and 2500 rpm, etc., and the stirring time is 5-18 min, specifically 5 min, 10 min, 15 min, and 18 min, etc.

[0042] In some embodiments of the present invention, since the high-speed stirring involved in the mixing process of graphene, polymer carrier and additives will cause the temperature to rise, in order to ensure that the graphene, polymer carrier and additives are fully mixed while avoiding graphene agglomeration, the mixing temperature is controlled to be <80°C.

[0043] In some embodiments of the present invention, the graphene is pretreated graphene, wherein the method for pretreating the graphene is as follows: mixing the graphene and an aqueous solution of a dispersant to obtain a premix, then subjecting the premix to ultrasonic treatment to obtain a dispersion, and then purifying the dispersion by centrifugation and freeze-drying.

[0044] The dispersant includes at least one selected from polyvinyl alcohol, sodium polyacrylate, sodium dodecylbenzene sulfonate, polydopamine, and cellulose nanocrystals; the mixing is carried out by stirring for 30-60 minutes, specifically 30 minutes, 40 minutes, 50 minutes, and 60 minutes; the ultrasonic power is 200-1000W, specifically 200W, 400W, 600W, 800W, and 1000W, and the ultrasonic time is 0.5-4 hours, specifically 0.5 hours, 1 hour, 2 hours, and 4 hours. The mass content of the dispersant in the premix is ​​2-15%, specifically 2%, 5%, 8%, 11%, and 15%, etc., and the mass percentage of graphene in the premix is ​​1-30%, specifically 15%, 20%, 25%, and 30%, etc.; freeze-drying can be carried out at -50°C for 24-48 hours until the water content of the graphene is less than 0.5%.

[0045] In this invention, the mixture is melt-extruded to obtain a melt, the melt is spun to obtain a matrix fiber, and graphene fibers are intercalated into the matrix fiber to obtain a graphene filter material.

[0046] In some embodiments of the present invention, the melt extrusion process adopts a six-zone gradient temperature control. From the feeding direction to the discharging direction, the six zones are set as zone I, zone II, zone III, zone IV, zone V and zone VI in sequence, and the temperatures of the above six zones are T1, T2, T3, T4, T5 and T6 in sequence, wherein T5 > T4 > T3 > T2 > T1, and T5 > T6. Specifically, T1 is 150-190℃, which can be 150℃, 160℃, 170℃, 180℃, 190℃, etc.; T2 is 160-200℃, which can be 160℃, 170℃, 180℃, 190℃, 200℃, etc.; T3 is 180-220℃, which can be 180℃, 190℃, 200℃, 210℃, 220℃, etc.; T4 is 200-230℃, which can be 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, etc.; T6 is 200-240℃, which can be 200℃, 210℃, 220℃, 230℃, 240℃, etc.

[0047] The melt extrusion process of this invention employs the above-mentioned six-zone gradient temperature control, which can make the graphene in the matrix fiber more uniformly dispersed and effectively avoid agglomeration. Specifically, the temperature in Zone I is relatively low, which can prevent graphene from agglomerating during the melt extrusion process and ensure stable delivery of the mixed material. The temperatures in Zones II, III, and IV gradually increase, which can soften the polymer carrier, reduce viscosity, and promote uniform dispersion of graphene. The temperature in Zone V is further increased, and the high temperature can enhance the mobility of the polymer carrier molecular chains and accelerate the diffusion of graphene. The temperature in Zone VI is reduced to stabilize the dispersion structure.

[0048] In some embodiments of the present invention, the melt extrusion process is carried out using a screw extruder, wherein the screw speed is 20-50 rpm, specifically 20 rpm, 30 rpm, 40 rpm, and 50 rpm, etc.

[0049] In some embodiments of the present invention, the spinning of the melt is performed by: conveying the melt to a meltblown die head, then distributing it to the spinneret orifice for spinning to form a melt stream, and then stretching the melt stream with hot air to obtain matrix fibers.

[0050] In some embodiments of the present invention, the melt is delivered to the meltblown die head by a metering pump. The metering pump rotates at 10-30 rpm, specifically 10 rpm, 20 rpm, or 30 rpm, and operates at 1-3 MPa, specifically 1 MPa, 2 MPa, or 3 MPa. The operating temperature is 220-240°C, specifically 220°C, 230°C, or 250°C. The temperature of the meltblown die head is 200-240°C, specifically 200°C, 210°C, 220°C, 230°C, or 240°C. The diameter of the spinneret orifice is 0.2-0.4 mm, specifically 0.2 mm, 0.3 mm, or 0.4 mm.

[0051] In some embodiments of the present invention, the spinneret distance is 150-400mm, specifically 150mm, 200mm, 250mm, 300mm, 350mm, and 400mm. If the spinneret distance is too small, the fiber distribution and entanglement will be uneven, affecting the product's strength and other mechanical properties. If the spinneret distance is too large, the fiber fineness will decrease, leading to reduced bonding efficiency and making delamination more likely, thus affecting product quality.

[0052] In some embodiments of the present invention, the wind speed of the hot air is 300-600 m / s, specifically 300 m / s, 350 m / s, 400 m / s, 450 m / s, 500 m / s, 550 m / s, and 600 m / s. Increasing the hot air speed allows for the formation of finer fibers, improving the filtration efficiency of graphene. However, if the wind speed is too high, excessive fiber entanglement can lead to a decrease in filtration efficiency.

[0053] In some embodiments of the present invention, the temperature of the hot air is 200-300°C, specifically 200°C, 250°C, and 300°C. If the hot air temperature is too high, it will damage the structure of the graphene material; if the temperature is too low, the high melt viscosity will make drawing difficult, affecting the uniformity and continuity of the fibers.

[0054] In some embodiments of the present invention, the intercalation of graphene fibers in matrix fibers specifically involves opening and combing the graphene fibers, and then blowing them into the matrix fibers near the spinneret holes using a fiber blowing device, thereby achieving the intercalation of graphene fibers between the matrix fibers.

[0055] In some embodiments of the present invention, the graphene fibers have a fineness of 1.5-9 dtex, specifically 1.5 dtex, 3 dtex, 5 dtex, 7 dtex, or 9 dtex; the graphene fibers have a length of 10-80 mm, specifically 10 mm, 20 mm, 40 mm, 60 mm, and 80 mm, etc. The finer the graphene fibers, the easier they are to disperse, and the shorter the length, the easier they are to disperse. Limiting the fineness and length of the graphene fibers within this range makes them easier to enter the matrix fibers and ensures good dispersibility. It should be noted that the graphene fibers need to be blown into the matrix fibers while remaining in a single-fiber state within the air duct.

[0056] In some embodiments of the present invention, the graphene content in the graphene fiber is 1-15%, specifically 1%, 5%, 10%, and 15%. If the graphene content in the graphene fiber is too high, the strength of the graphene fiber will decrease, while if the graphene content is too low, the filtration efficiency of the product, such as antibacterial, antiviral, and formaldehyde removal, will be low.

[0057] In some embodiments of the present invention, the graphene fiber is a synthetic fiber or a blended fiber, wherein the blended fiber is made by blending synthetic fibers and graphene, and the synthetic fiber includes at least one of polyester, acrylic, polypropylene, spandex and vinylon.

[0058] In some embodiments of the present invention, the intercalation speed is 2-50 m / s, such as 2 m / s, 10 m / s, 20 m / s, 30 m / s, 40 m / s, and 50 m / s. It should be noted that the intercalation speed specifically refers to the airflow speed when the fiber blowing device sprays graphene fibers onto the matrix fibers. If the intercalation speed is too slow, the graphene fibers will not be fully embedded between the matrix fibers, but will instead be mostly distributed on the surface of the fiber web formed by the matrix fibers. If the speed is too fast, the graphene fibers will be difficult to disperse evenly, resulting in excessively high local graphene fiber concentrations, causing uneven distribution of graphene fibers in the product and poor filtration effect.

[0059] In some embodiments of the present invention, the intercalation distance is 5-20 cm, specifically 5 cm, 10 cm, 15 cm, and 20 cm. It should be noted that the intercalation distance specifically refers to the vertical distance between the nozzle outlet of the fiber blowing device and the center line of the matrix fiber injection, i.e., the path length of the airflow carrying the graphene fiber from injection to contact with the matrix fiber. If the intercalation distance is too far, the graphene fiber will be difficult to disperse and adhere between the matrix fiber streams; if the distance is too close, the graphene fiber distribution uniformity will be poor.

[0060] In some embodiments of the present invention, the intercalation angle is 15-90°, specifically 15°, 30°, 60°, 75°, and 90°, etc. It should be noted that the intercalation angle specifically refers to the angle between the direction of graphene fiber blowing and the direction of matrix fiber spraying (the axial direction of the spinneret). Small-angle blowing can achieve the same orientation of the graphene fibers and the melt stream, promoting the refinement of the matrix fibers. Large-angle blowing can achieve a random distribution of graphene fibers. This can be adjusted according to the actual process to obtain graphene materials with different properties.

[0061] In some embodiments of the present invention, after intercalating graphene fibers into matrix fibers, the method further includes the following steps: the matrix fibers intercalated with graphene fibers are received by rollers and cooled into a web, which is then slit and wound up to obtain a rolled graphene filter material.

[0062] In another aspect, the present invention also provides a graphene filter material prepared by the method described in any of the preceding claims. This graphene filter material exhibits excellent antibacterial, antiviral, and filtration properties.

[0063] The technical solutions of this invention will be clearly and completely described below with reference to specific embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0064] Example 1

[0065] This embodiment provides a graphene filter material, and the specific steps are as follows:

[0066] (1) Prepare a 5% sodium dodecylbenzenesulfonate aqueous solution, then add monolayer graphene, and premix by magnetic stirring for 30 min to obtain a premixed solution (the mass percentage of monolayer graphene in the premixed solution is 20%). Then, sonicate the premixed solution at 1000W power for 1 h, purify by centrifugation, and freeze dry in a freeze dryer at -50℃ for 30 h to obtain pretreated graphene.

[0067] (2) By mass percentage, 23% pretreated graphene, 0.4% mineral oil, 0.5% pp-g-MAH, 1% antioxidant B215 and 0.1% UV-531 were premixed and then added to 70% polypropylene. The mixture was stirred at 500 rpm for 10 min to obtain a premix. 5% heavy calcium carbonate powder was added to the premix and stirred at 2000 rpm for 12 min. The temperature was controlled at 50℃ throughout the process to obtain a mixture.

[0068] (3) The mixture is added to an extruder with a screw speed of 20 rpm and melted and extruded to obtain a melt. The melt is transported to the meltblown die by a metering pump and distributed to the spinneret orifice for spinning to form a fine melt stream. The fine melt stream is stretched by hot air to obtain matrix fibers.

[0069] The melt extrusion process employs a six-zone gradient temperature control. From the feeding direction to the discharging direction, the temperatures of zones I, II, III, IV, V, and VI are 150℃, 160℃, 190℃, 210℃, 230℃, and 220℃, respectively. The metering pump operates at a speed of 15 rpm, a working pressure of 2.5 MPa, and a working temperature of 220℃. The meltblown die temperature is 230℃, the diameter of the spinneret orifice is 0.4 mm, the spinneret distance is 300 mm, and the hot air temperature is 250℃ with a wind speed of 400 m / s.

[0070] (4) The blended fiber with a graphene content of 7% (made of polyester and graphene, with a fineness of 3dtex and a length of 32mm) is opened and combed. While spinning to form the matrix fiber, the combed blended fiber is blown into the matrix fiber near the spinneret hole by a fiber blowing device to realize the intercalation of graphene fiber between the matrix fiber. The intercalation speed is 5m / s, the distance is 8cm, and the angle is 90°. After being received by rollers and cooled into a web, it is cut and wound to obtain a rolled graphene filter material.

[0071] Example 2

[0072] This embodiment provides a graphene filter material, and the specific steps are as follows:

[0073] (1) Prepare a 7% polydopamine aqueous solution, then add multilayer graphene, and premix by magnetic stirring for 50 min to obtain a premixed solution (the mass percentage of multilayer graphene in the premixed solution is 25%). Then, sonicate the premixed solution at 400W power for 1 h, purify by centrifugation, and freeze dry in a freeze dryer at -50℃ for 48 h to obtain pretreated graphene.

[0074] (2) By mass percentage, 20% pretreated graphene, 0.4% ester oil, 0.5% pp-g-MAH, 0.5% antioxidant B215 and 0.1% UV-531 were premixed and then added to 70% polypropylene. The mixture was stirred at 500 rpm for 9 min to obtain a premix. 8.5% heavy calcium carbonate powder was added to the premix and stirred at 1500 rpm for 18 min. The temperature was controlled at 40℃ throughout the process to obtain a mixture.

[0075] (3) The mixture is added to an extruder with a screw speed of 25 rpm and melted and extruded to obtain a melt. The melt is transported to the meltblown die by a metering pump and distributed to the spinneret orifice for spinning to form a fine melt stream. The fine melt stream is stretched by hot air to obtain matrix fibers.

[0076] The melt extrusion process employs a six-zone gradient temperature control. From the feed direction to the discharge direction, the temperatures of zones I, II, III, IV, V, and VI are 160℃, 170℃, 190℃, 210℃, 250℃, and 230℃, respectively. The metering pump operates at a speed of 20 rpm, a working pressure of 2 MPa, and a working temperature of 230℃. The temperature of the meltblown die is 225℃, the diameter of the spinneret orifice is 0.2 mm, the spinneret distance is 350 mm, and the hot air temperature is 270℃ with a wind speed of 450 m / s.

[0077] (4) The blended fiber with a graphene content of 10% (made of polyester and graphene blended fiber with a fineness of 4dtex and a length of 35mm) is opened and combed. While spinning to form matrix fiber, the combed blended fiber is blown into the matrix fiber near the spinneret hole by a fiber blowing device to realize the intercalation of graphene fiber between matrix fiber. The intercalation speed is 15m / s, the distance is 14cm and the angle is 90°. After being received by rollers and cooled into a web, it is cut and wound to obtain a rolled graphene filter material.

[0078] Example 3

[0079] This embodiment provides a graphene filter material, and the specific steps are as follows:

[0080] (1) Prepare a 7% polydopamine aqueous solution, then add multilayer graphene, and premix by magnetic stirring for 45 min to obtain a premixed solution (the mass percentage of multilayer graphene in the premixed solution is 25%). Then, sonicate the premixed solution at 500W power for 1 h, purify by centrifugation, and freeze dry in a freeze dryer at -50℃ for 48 h to obtain pretreated graphene.

[0081] (2) By mass percentage, 8% pretreated graphene, 0.4% mineral oil, 0.5% pp-g-MAH, 1% antioxidant B215 and 0.1% UV-234 were premixed and then added to 82.5% polypropylene. The mixture was stirred at 500 rpm for 8 min to obtain a premix. 7.5% talc was added to the premix and stirred at 2000 rpm for 7 min. The temperature was controlled at 65℃ throughout the process to obtain a mixture.

[0082] (3) The mixture is added to an extruder with a screw speed of 25 rpm and melted and extruded to obtain a melt. The melt is transported to the meltblown die by a metering pump and distributed to the spinneret orifice for spinning to form a fine melt stream. The fine melt stream is stretched by hot air to obtain matrix fibers.

[0083] The melt extrusion process employs a six-zone gradient temperature control. From the feeding direction to the discharging direction, the temperatures of zones I, II, III, IV, V, and VI are 180℃, 190℃, 200℃, 215℃, 230℃, and 220℃, respectively. The metering pump operates at a speed of 25 rpm, a working pressure of 2.5 MPa, and a working temperature of 225℃. The meltblown die temperature is 230℃, the diameter of the spinneret orifice is 0.25 mm, the spinneret distance is 335 mm, and the hot air temperature is 250℃ with a wind speed of 370 m / s.

[0084] (4) The blended fiber with a graphene content of 10% (made of polypropylene and graphene, with a fineness of 6dtex and a length of 50mm) is opened and combed. While spinning to form the matrix fiber, the combed blended fiber is blown into the matrix fiber near the spinneret through the fiber blowing device to realize the intercalation of graphene fiber between the matrix fiber. The intercalation speed is 10m / s, the distance is 6cm, and the angle is 30°. After being received by the roller, it is cooled into a web. After being slit and wound up, the graphene filter material is obtained in rolls.

[0085] Example 4

[0086] This embodiment provides a graphene filter material, and the specific steps are as follows:

[0087] (1) Prepare a 10% sodium polyacrylate aqueous solution, then add multilayer graphene, and premix by magnetic stirring for 30 min to obtain a premixed solution (the mass percentage of multilayer graphene in the premixed solution is 15%). Then, sonicate the premixed solution at 800W for 1.5 h, purify by centrifugation, and freeze dry in a freeze dryer at -50℃ for 48 h to obtain pretreated graphene.

[0088] (2) By mass percentage, 20% pretreated graphene, 0.4% mineral oil, 0.5% pp-g-MAH, 1% antioxidant B215 and 0.1% UV-234 were premixed and then added to 69.5% polypropylene. The mixture was stirred at 500 rpm for 10 min to obtain a premix. 8.5% talc was added to the premix and stirred at 1500 rpm for 10 min. The temperature was controlled at 55℃ throughout the process to obtain a mixture.

[0089] (3) The mixture is added to an extruder with a screw speed of 25 rpm and melted and extruded to obtain a melt. The melt is transported to the meltblown die by a metering pump and distributed to the spinneret orifice for spinning to form a fine melt stream. The fine melt stream is stretched by hot air to obtain matrix fibers.

[0090] The melt extrusion process employs a six-zone gradient temperature control. From the feed direction to the discharge direction, the temperatures of zones I, II, III, IV, V, and VI are 170℃, 195℃, 210℃, 225℃, 240℃, and 220℃, respectively. The metering pump operates at a speed of 20 rpm, a working pressure of 3 MPa, and a working temperature of 240℃. The meltblown die temperature is 230℃, the spinneret diameter is 0.3 mm, the spinneret distance is 275 mm, and the hot air temperature is 315℃ with a wind speed of 500 m / s.

[0091] (4) The blended fiber with a graphene content of 2.7% (made of acrylic fiber and graphene blended fiber with a fineness of 3dtex and a length of 30mm) is opened and combed. While spinning to form matrix fiber, the combed blended fiber is blown into the matrix fiber near the spinneret through the fiber blowing device to realize the intercalation of graphene fiber between the matrix fiber. The intercalation speed is 20m / s, the distance is 18cm and the angle is 60°. After being received by rollers and cooled into a web, it is cut and wound to obtain a rolled graphene filter material.

[0092] Example 5

[0093] This embodiment is basically the same as embodiment 1, except that step (4) is different.

[0094] (4) The blended fiber with a graphene content of 17% (made of acrylic fiber and graphene blended fiber with a fineness of 6dtex and a length of 55mm) is opened and combed. While spinning to form matrix fiber, the combed blended fiber is blown into the matrix fiber near the spinneret through the fiber blowing device to realize the intercalation of graphene fiber between the matrix fiber. The intercalation speed is 7.50m / s, the distance is 20cm, and the angle is 90°. After being received by rollers and cooled into a web, it is cut and wound to obtain a rolled graphene filter material.

[0095] Example 6

[0096] This embodiment is basically the same as embodiment 2, except that steps (3) and (4) are different.

[0097] (3) The mixture is added to an extruder with a screw speed of 20 rpm and melted and extruded to obtain a melt. The melt is transported to the meltblown die by a metering pump and distributed to the spinneret orifice for spinning to form a fine melt stream. The fine melt stream is stretched by hot air to obtain matrix fibers.

[0098] The melt extrusion process employs a six-zone gradient temperature control. From the feeding direction to the discharging direction, the temperatures of zones I, II, III, IV, V, and VI are 175℃, 190℃, 205℃, 215℃, 230℃, and 215℃, respectively. The metering pump operates at a speed of 20 rpm, a working pressure of 2 MPa, and a working temperature of 235℃. The meltblown die temperature is 230℃, the diameter of the spinneret orifice is 0.3 mm, the spinneret distance is 400 mm, and the hot air temperature is 260℃ with a wind speed of 550 m / s.

[0099] (4) The blended fiber with a graphene content of 5% (made of polypropylene and graphene, with a fineness of 4dtex and a length of 50mm) is opened and combed. While spinning to form the matrix fiber, the combed blended fiber is blown into the matrix fiber near the spinneret hole by a fiber blowing device to realize the intercalation of graphene fiber between the matrix fiber. The intercalation speed is 10m / s, the distance is 8cm, and the angle is 90°. After being received by rollers and cooled into a web, it is cut and wound to obtain a rolled graphene filter material.

[0100] Comparative Example 1

[0101] This comparative example is basically the same as Example 1, except that in step (2), the content of each raw material is as follows by mass percentage: 40% pretreated single-layer graphene, 50% polypropylene, 8% heavy calcium carbonate powder, 0.4% mineral oil, 0.5% pp-g-MAH, 1% antioxidant B215 and 0.1% UV-531 material.

[0102] In the graphene material prepared in this comparative example, polypropylene could not coat high-content monolayer graphene. The graphene sheets aggregated into micron-sized clumps, which disrupted the fiber continuity and hindered the spinning process, making it impossible to obtain an effective fiber layer.

[0103] Comparative Example 2

[0104] This comparative example is basically the same as Example 1, except that the wind speed of the hot air in step (3) is 1000m / s and the distance of the filament is 800mm; the speed of the intercalation in step (4) is 1m / s and the distance is 50cm.

[0105] Comparative Example 3

[0106] This comparative example is basically the same as Example 1, except that in step (2), the content of each raw material by mass percentage is as follows: 0.1% pretreated single-layer graphene, 90% polypropylene, 8% heavy calcium carbonate powder, 0.4% mineral oil, 0.4% pp-g-MAH, 1% antioxidant B215 and 0.1% UV-531 material; and in step (4), the graphene content in the blended fiber is 10%.

[0107] Comparative Example 4

[0108] This comparative example is basically the same as Example 2, except that the intercalation distance in step (4) is 2m and the angle is 5°.

[0109] Comparative Example 5

[0110] This comparative example is basically the same as Example 3, except that the temperatures of Zone I, Zone II, Zone III, Zone IV, Zone V and Zone VI in step (3) are 140℃, 150℃, 165℃, 180℃, 200℃ and 250℃, respectively.

[0111] Comparative Example 6

[0112] This comparative example is basically the same as Example 4, except that after obtaining the matrix fiber in step (3), it is cooled and formed into a web, then cut and wound up, without performing the intercalation operation in step (4).

[0113] The filtration efficiency, resistance, antibacterial properties, antiviral properties, and formaldehyde adsorption properties of the graphene filter materials in Examples 1-6 and Comparative Examples 1-6 were tested, and the results are shown in Table 1.

[0114] The filtration efficiency and resistance tests were conducted according to GB / T 38413-2019 "Test Methods for Filtration Performance of Fine Particulate Matter in Textiles", with the test particles being saline aerosols, a gas flow rate of 32 L / min, and a particle diameter of 0.075 ± 0.020 μm. The antibacterial performance tests were conducted according to GB / T 20944.3-2008 "Evaluation of Antibacterial Properties of Textiles - Part 3: Shaking Method", with the test strains being Staphylococcus aureus, Escherichia coli, and Candida albicans. The antiviral performance tests were conducted according to ISO... According to standard 18184-2019 "Determination of antiviral activity of textiles", the virus tested was influenza A virus A / PR / 8 / 34H1N1, and the host was MDCK cells. The test method for formaldehyde adsorption performance was as follows: first, formaldehyde solution was placed for 24 hours to generate a sufficient concentration of formaldehyde gas. Then, graphene filter material was placed in a vacuum chamber and the chamber was evacuated. Finally, 500 mL of formaldehyde gas and 2.5 L of fresh air were pumped into the vacuum chamber and allowed to stand for 24 hours to mix thoroughly. The formaldehyde concentration was recorded using a formaldehyde detector calibrated by the phenol reagent spectrophotometric method.

[0115] Table 1 Performance Test Results

[0116]

[0117] As can be seen from Table 1, the graphene filter material prepared by this invention has good filtration performance, can effectively inhibit bacteria and viruses, and has a good formaldehyde removal effect.

[0118] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a graphene filter material, characterized in that, Includes the following steps: (1) Graphene and polymer support are mixed to obtain a mixture; in the mixture, the content of graphene is 1-30%; (2) The mixture is melt-extruded to obtain a melt, the melt is spun to obtain a matrix fiber, and graphene fibers are intercalated in the matrix fiber to obtain a graphene filter material. The intercalation speed is 2-50 m / s, and the intercalation distance is 5-20 cm; The graphene fibers have a fineness of 1.5-9 dtex and a length of 10-80 mm. The melt extrusion process employs a six-zone gradient temperature control. From the feed to the discharge direction, the temperatures of the six zones are T1, T2, T3, T4, T5, and T6, where T5 > T4 > T3 > T2 > T1, and T5 > T6. T1 is 150-190℃, T2 is 160-200℃, T3 is 180-220℃, T4 is 200-230℃, T5 is 210-250℃, and T6 is 200-240℃. The intercalation angle is 15-90°.

2. The method for preparing the graphene filter material according to claim 1, characterized in that, The mixture also includes additives, wherein the polymer carrier comprises 55-98% by mass and the additives comprise 1-15% by mass. The mixing temperature is <80℃.

3. The method for preparing the graphene filter material according to claim 2, characterized in that, The graphene includes at least one of monolayer graphene, multilayer graphene, graphene oxide, carbon nanotubes, and graphene quantum dots. The polymer carrier includes at least one of polypropylene, polyacrylonitrile, polylactic acid, polyamide, polyethylene, polyvinyl alcohol, and polyester; The additives include at least one of inorganic fillers, lubricants, compatibilizers, antioxidants, and ultraviolet absorbers.

4. The method for preparing the graphene filter material according to claim 1, characterized in that, The process of spinning the melt involves: conveying the melt to a meltblown die head, then distributing it into spinnerets for spinning to form a fine melt stream, which is then stretched by hot air to obtain matrix fibers; The melt is delivered to the meltblown die head by a metering pump, the metering pump having a rotation speed of 10-30 rpm, a working pressure of 1-3 MPa, and a working temperature of 220-240℃. The temperature of the meltblown die head is 200-240℃, the diameter of the spinneret orifice is 0.2-0.4mm, and the distance between the spinnerets is 150-400mm. The wind speed of the hot air is 300-600 m / s, and the temperature of the hot air is 200-300℃.

5. The method for preparing the graphene filter material according to claim 1, characterized in that, The graphene content in the graphene fiber is 1-15%; The graphene fiber is a synthetic fiber or a blended fiber. The blended fiber is made by blending synthetic fibers and graphene. The synthetic fiber includes at least one of polyester, acrylic, polypropylene, spandex and vinylon.

6. The method for preparing the graphene filter material according to any one of claims 1-5, characterized in that, The graphene is pretreated graphene, and the method for pretreating the graphene is as follows: the graphene and the aqueous solution of the dispersant are mixed to obtain a premix, the premix is ​​then ultrasonically treated to obtain a dispersion, and the dispersion is purified by centrifugation and then freeze-dried. The dispersant mentioned above includes at least one of polyvinyl alcohol, sodium polyacrylate, sodium dodecylbenzenesulfonate, polydopamine, and cellulose nanocrystals; The ultrasonic power is 200-1000W, and the ultrasonic time is 0.5-4h.

7. A graphene filter material prepared by the method according to any one of claims 1-6.

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