CN114620738A - Preparation method and application of rectorite nanosheet - Google Patents
Preparation method and application of rectorite nanosheet Download PDFInfo
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- D21H19/40—Coatings with pigments characterised by the pigments siliceous, e.g. clays
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Abstract
The invention provides a preparation method of a rectorite nanosheet, which comprises the following steps: the method for preparing the ultrathin rectorite nanosheet by using the polyvinylpyrrolidone as the auxiliary stirring stripping method and using rich natural rectorite micron sheets as the raw material has the thickness of 5-10 nm, and simultaneously realizes higher yield than most other nanosheets. The method utilizes a polydiene dimethyl ammonium chloride auxiliary precipitation strategy to replace high-speed centrifugation, and realizes the rapid separation of the peeled ultrathin rectorite nanosheet from the suspension. The invention also provides an application of the rectorite nano-sheets, the rectorite nano-sheets and the aramid nano-fibers are assembled into a large amount of nano paper imitating the pearl layer rectorite nano-sheets-aramid nano-fibers, compared with the pure aramid nano-fiber nano-paper and the rectorite micron-sheet-aramid nano-fiber micron paper, the mechanical, electrical insulation and high temperature resistance of the nano paper are greatly enhanced, and the performances are also superior to those of the nano paper based on the aramid nano-fibers and the commercial micron insulation paper.
Description
Technical Field
The invention belongs to the technical field of nano materials, and particularly relates to a preparation method and application of a rectorite nanosheet, in particular to a large-scale production method of the rectorite nanosheet and application of the rectorite nanosheet in high-performance electric insulating paper.
Background
Due to the fascinating mechanical and physical properties, the phyllosilicate mineral has wide application in the fields of electrical insulation composite materials, mechanical reinforcing materials, flame retardant materials, flexible devices and the like. The phyllosilicate mineral has the advantages of rich resources, low cost, environmental protection and the like, and is recognized as an important raw material in the 21 st century. In particular, rectorite, which is formed by alternately stacking montmorillonite-like layers and mica-like layers, inherits the advantages of montmorillonite (such as plasticity and adsorptivity) and mica (such as mechanical properties and electrical insulation), becomes an attractive nano-structural unit for manufacturing various high-performance composite materials.
Compared with micron-sized silicate particles, the ultrathin silicate nanosheet has a larger length-diameter ratio and higher surface reactivity, so that the ultrathin silicate nanosheet has significantly enhanced comprehensive performance. To prepare rectorite nanosheets, a number of polymer intercalation assisted exfoliation methods have been developed, such as in situ polymerization, melt intercalation, and solution intercalation. Although these methods can successfully exfoliate rectorite at present, simple and efficient preparation of monodisperse rectorite nanosheets has not been achieved.
Disclosure of Invention
In view of the above, the present invention provides a method for preparing a rectorite nanosheet and an application thereof, the method provided by the present invention can rapidly separate and exfoliate the rectorite nanosheet, and the prepared electrical insulating paper has good mechanical properties, electrical insulating properties and high temperature stability.
The invention provides a preparation method of a rectorite nanosheet, which comprises the following steps:
dispersing rectorite powder and polyvinylpyrrolidone in a solvent, stirring, and then separating by adopting a natural sedimentation method to obtain a rectorite nanosheet suspension;
and collecting the rectorite nanosheets in the rectorite nanosheet suspension by adopting a cation-assisted precipitation method to obtain the rectorite nanosheets.
Preferably, the solvent is one or more selected from water, ethanol, isopropanol, N-dimethylformamide and dimethyl sulfoxide.
Preferably, the mass ratio of the rectorite powder to the polyvinylpyrrolidone is (5-20) to (40-80).
Preferably, the reagent used in the cation-assisted precipitation process is one or more selected from polydiallyl dimethyl ammonium chloride and polyethyleneimine.
Preferably, the natural settling time is 1-10 hours.
Preferably, the volume ratio of the cation dispersion liquid to the rectorite nanosheet suspension in the cation-assisted precipitation process is 1: (50-500).
The present invention provides an electrical insulating paper comprising: the rectorite nanosheet prepared by the method in the technical scheme is provided.
The invention provides a preparation method of electric insulating paper, which comprises the following steps:
mixing a rectorite nanosheet solution and an aramid nanofiber solution to obtain a dispersion liquid;
spraying the dispersion liquid to obtain the electric insulating paper;
the rectorite nanosheet solution contains the rectorite nanosheet prepared by the method in the technical scheme.
Preferably, the aramid nanofiber solution comprises:
aramid fiber, water, potassium hydroxide and dimethyl sulfoxide.
Preferably, the mass content of the rectorite nanosheets in the dispersion liquid is 10-40%.
Liquid phase exfoliation offers several advantages over polymer intercalation-assisted exfoliation in terms of simplicity, low cost and ease of industrialization, such as efficient production of large quantities of graphene and other layered nanoplatelets (e.g. molybdenum disulfide and boron nitride) by high shear treatment in certain surfactant solutions. However, how to rapidly separate and collect exfoliated ultrathin nanoplatelets from solution is also a challenge. According to the invention, a polydiene dimethyl ammonium chloride-assisted precipitation strategy is used for replacing high-speed centrifugation, so that the effect of quickly separating and stripping ultrathin rectorite nanosheets from the suspension is realized, and the prepared rectorite nanosheet-aramid nanofiber composite material with the nacre-like structure realizes excellent mechanical property, electrical insulation property and high-temperature stability.
The invention successfully realizes the high-efficiency large-scale preparation of the redispersible solid-phase rectorite nanosheet with a few layers of ultrathin thickness and high aspect ratio from abundant natural rectorite powder through the combination of polyvinylpyrrolidone assisted stirring stripping, poly (diallyldimethylammonium chloride) assisted precipitation and freeze drying. The invention adopts high-quality rectorite nano-sheets and aramid nano-fibers as ideal elements to prepare the novel imitation mother-of-pearl rectorite nano-sheet-aramid nano-fiber nano-paper, and the imitation mother-of-pearl rectorite nano-sheet-aramid nano-fiber nano-paper has the key performance of electrical insulation application. Due to the inherent advantages of the rectorite nanosheets and the aramid nanofibers and the microstructure of the pearl-like layer, the optimized rectorite nanosheet-aramid nanofiber nanopaper has excellent mechanical property, high electrical insulation property and good high temperature resistance. Compared with aramid nanofibers, rectorite micron sheets-aramid nanofibers and commercial micro-insulation paper, the excellent performance combination enables the rectorite nanosheet-aramid nanofibers to become an ideal insulation material working in a severe actual industrial environment, an extensible method is provided for efficiently preparing high-quality rectorite nanosheets, and a new way is opened up for developing advanced rectorite-based nanocomposite materials for various applications.
Drawings
FIG. 1 is a process flow diagram for the preparation of rectorite nanosheets according to example 1 of the present invention;
FIG. 2 shows the micro-morphology of the rectorite micron sheet used in example 1 of the present invention (a is a scanning electron microscope picture, b is a transmission electron microscope picture, and c is a large stirring and peeling picture);
fig. 3 is a transmission photograph of rectorite nanosheets prepared in water, ethanol, formamide, isopropanol and dimethyl sulfoxide respectively by polyvinylpyrrolidone-assisted mechanical stirring and stripping method in example 1 of the present invention (a is water, b is ethanol, c is formamide, d is isopropanol and e is dimethyl sulfoxide);
FIG. 4 is a photograph of rectorite nanosheets prepared by rapid collection combining natural sedimentation and cation-assisted precipitation in example 2 of the present invention;
FIG. 5 is a thickness characterization of rectorite nanoplates prepared in example 2 of the present invention;
FIG. 6 shows the results of testing the mechanical properties and high temperature resistance of the nacre-like rectorite nanosheet-aramid nanofiber nanopaper prepared in embodiment 3 of the present invention;
fig. 7 is a result of testing the electrical insulation performance and the high temperature resistance performance of the nacre-like structured nanopaper prepared in example 3 of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a preparation method of a rectorite nanosheet, which comprises the following steps:
dispersing rectorite powder and polyvinylpyrrolidone in a solvent, stirring, and then separating by adopting a natural sedimentation method to obtain a rectorite nanosheet suspension;
and collecting the rectorite nanosheets in the rectorite nanosheet suspension by adopting a cation-assisted precipitation method to obtain the rectorite nanosheets.
In the invention, the rectorite powder is preferably natural rectorite powder, more preferably rectorite micron sheets, and the transverse dimension of the rectorite micron sheets is preferably 10-30 microns, more preferably 15-25 microns.
In the invention, the mass ratio of the rectorite powder to the polyvinylpyrrolidone is preferably (5-20): (40-80), more preferably (10-15): (50-70), most preferably 12: 60.
in the invention, the dosage ratio of the rectorite powder to the solvent is preferably (5-20) g: 1000mL, more preferably (10-15) g: 1000mL, most preferably 12 g: 1000 mL.
In the present invention, the stirring is preferably mechanical stirring to achieve exfoliation of the rectorite nanosheets. In the present invention, the time period of the mechanical stirring is preferably 20 to 60 hours, more preferably 30 to 50 hours, and most preferably 40 hours.
In the present invention, the solvent is preferably one or more selected from the group consisting of water, ethanol, isopropanol, N-dimethylformamide, and dimethylsulfoxide.
In the present invention, separation of exfoliated rectorite nanosheets and non-exfoliated rectorite nanosheets is achieved by a natural sedimentation method. In the invention, the time of the natural sedimentation is preferably 1 to 10 hours, more preferably 2 to 8 hours, and most preferably 3 to 6 hours. In the present invention, it is preferable that the natural settling further comprises:
and carrying out subsequent separation treatment on the obtained upper-layer rectorite nanosheet suspension.
In the invention, in the process of the cation-assisted precipitation method, a reagent is preferably selected from one or more of polydiallyl dimethyl ammonium chloride and polyethyleneimine, more preferably a cation dispersion liquid, wherein the cation dispersion liquid is a solution prepared by the reagent in the technical scheme, and a solvent in the solution is preferably water; the mass concentration of the solution (cationic dispersion) is preferably 1 to 10%, more preferably 2 to 8%, and most preferably 3 to 6%.
In the invention, in the cation-assisted precipitation process, the volume ratio of the cation dispersion liquid to the rectorite nanosheet suspension liquid is preferably 1: (50 to 500), more preferably 1: (100-400), most preferably 1: (200-300).
In the invention, preferably, in the process of cation-assisted precipitation, a cation dispersion liquid is dropwise added into a rectorite nanosheet suspension liquid, after the rectorite nanosheet is precipitated, an upper layer liquid is poured, and a lower layer rectorite nanosheet is subjected to suction filtration, washing and freeze drying to obtain a solid phase rectorite nanosheet.
In the present invention, it is preferable that the collecting further comprises:
and filtering, washing and drying the obtained collected product (lower-layer product) to obtain the solid-phase rectorite nanosheet.
In the present invention, the filtration method is preferably suction filtration.
In the present invention, the method of drying is preferably freeze-drying.
The present invention provides an electrical insulating paper comprising: the rectorite nanosheet prepared by the method in the technical scheme is provided.
In the present invention, the thickness of the electric insulating paper is preferably 10 to 40 μm, more preferably 20 to 30 μm, and most preferably 25 μm.
The invention provides a preparation method of electric insulating paper, which comprises the following steps:
mixing a rectorite nanosheet solution and an aramid nanofiber solution to obtain a dispersion liquid;
spraying the dispersion liquid to obtain the electric insulating paper;
the rectorite nanosheet solution contains the rectorite nanosheet prepared by the method in the technical scheme.
In the present invention, the method for preparing the rectorite nanosheet solution preferably includes:
and dispersing the rectorite nanosheet in a solvent to obtain a rectorite nanosheet solution.
In the present invention, the solvent is preferably one or more selected from the group consisting of water, ethanol, isopropanol, N-dimethylformamide, and dimethylsulfoxide.
In the present invention, the method of dispersion is preferably ultrasonic dispersion.
In the present invention, the aramid nanofiber solution preferably includes:
aramid fiber, water, potassium hydroxide and dimethyl sulfoxide.
In the invention, the dosage proportion of the aramid fiber, water, potassium hydroxide and dimethyl sulfoxide is preferably (10-20) g: (50-100) g: (10-20) g: (1-2) L, more preferably (13-17) g: (60-90) g: (13-17) g: (1.3-1.7) L, most preferably 15 g: (70-80) g: 15 g: 1.5L.
The preparation method of the aramid nano-fiber solution is not particularly limited, and all the components in the aramid nano-fiber solution are mechanically stirred.
In the present invention, the method of mixing is preferably shear.
In the present invention, the content by mass of the rectorite nanosheets in the dispersion is preferably 10 to 40%, more preferably 20 to 30%, and most preferably 25%.
In the present invention, the spraying is preferably performed on the surface of the substrate; the substrate is preferably a glass substrate.
In the invention, after the spraying, gel is formed, and preferably, the gel is soaked and dried in water for one time to obtain the composite membrane; and (3) soaking and drying the composite film in water for the second time to obtain the nacre-imitated rectorite nanosheet-aramid nano-fiber insulating paper (electrical insulating paper).
In the present invention, the water is preferably deionized water; the time for the primary soaking is preferably 10-15 hours, and more preferably 12-13 hours; the temperature of the primary drying is preferably normal temperature, more preferably 20-30 ℃, and most preferably 25 ℃; the time for primary drying is preferably 45 to 55 hours, and more preferably 48 to 52 hours. In the present invention, the selection range of the process parameters of the secondary soaking and the secondary drying is consistent with the selection range of the process parameters of the primary soaking and the primary drying, and details are not repeated herein.
In the present invention, the method for preparing the electrical insulating paper preferably comprises:
dispersing natural rectorite powder and polyvinylpyrrolidone in a solvent, and mechanically stirring to realize the peeling of the rectorite nanosheet;
separating the rectorite nanosheets from the unreleased rectorite powder by adopting a natural sedimentation method to obtain a rectorite nanosheet suspension, rapidly collecting the rectorite nanosheets by adopting a cation-assisted precipitation method, and obtaining solid-phase rectorite nanosheets by suction filtration, washing and freeze drying; dispersing solid-phase rectorite nanosheets in a solvent by utilizing ultrasound to obtain a rectorite nanosheet solution;
stirring and stripping aramid fibers in a solvent to obtain an aramid nanofiber solution; mixing a rectorite nanosheet solution and an aramid nanofiber solution to obtain a rectorite nanosheet-aramid nanofiber dispersion solution;
and spraying the rectorite nanosheet-aramid nanofiber dispersion liquid into a composite film by adopting a spraying assembly method, so as to obtain the electric insulating paper.
Compared with the prior art, the invention provides a method for large-scale production of rectorite nanosheets and application thereof in high-performance electric insulating paper, which comprises the following steps: A) dispersing natural rectorite powder and polyvinylpyrrolidone in a solvent, and mechanically stirring to realize the peeling of the rectorite nanosheet; B) separating stripped rectorite nanosheets and unreleased rectorite powder by adopting a natural sedimentation method to obtain a rectorite nanosheet suspension, rapidly collecting the rectorite nanosheets by adopting a cation-assisted precipitation method, and obtaining solid-phase rectorite nanosheets by suction filtration, washing and freeze drying; dispersing solid phase rectorite nanosheets in a solvent by using ultrasound to obtain a mica nanosheet suspension; C) stirring and stripping aramid fibers in a solvent to obtain an aramid nanofiber solution; mixing the rectorite nanosheet suspension with the aramid nanofiber dissolving solution to obtain a rectorite nanosheet-aramid nanofiber dispersion liquid; spraying the rectorite nanosheet-aramid nanofiber dispersion liquid into a composite film by adopting a spraying assembly method.
The rectorite micron sheet adopted in the following embodiment of the invention is a micron sheet provided by Hubei Mingliu Co., Ltd, and FIG. 2 is a scanning electron microscope picture and a transmission electron microscope picture thereof, and it can be seen that the transverse dimension of the rectorite micron sheet is about 17 microns and is very thick; aramid fibers (K49) are available from dupont.
Example 1 Macro preparation of rectorite nanoplatelets
The preparation is carried out according to the process flow chart shown in figure 1:
adding 20g of raw rectorite powder (rectorite micron tablet) and 96g of polyvinylpyrrolidone into 2000mL of dispersant, stirring at room temperature for 12h, and collecting 10mL of dispersion for 3000r min-1Centrifuging for 10min to collect the upper suspension, adopting different reagents (respectively water, ethanol, formamide and dimethyl sulfoxide), wherein the obtained nano-sheets have different mass, as can be seen from fig. 3, the solvent selected formamide rectorite nano-sheet has better mass, and fig. 3 is a transmission microscope photograph of the rectorite nano-sheet prepared in embodiment 1 of the invention.
Example 2
According to the method of the embodiment 1, 2000mL of dispersion liquid is prepared, the dispersing agent is formamide, then natural settling is carried out for 3h (different times such as 1.5 h and 6 h can be replaced), then 2mL of polydiene dimethyl ammonium chloride solution with the mass concentration of 4% is added, collection of the rectorite nanosheets is achieved for 20min, then suction filtration, washing and freeze drying are carried out, solid phase rectorite nanosheets are obtained, 0.54g of rectorite nanosheets can be obtained from each liter of dispersion liquid, and 80g of solid phase rectorite nanosheets can be obtained by preparing 148L of dispersion liquid.
The obtained solid phase rectorite nanosheet can be re-dispersed in different solvents (such as water, ethanol, formamide and dimethyl sulfoxide), the thickness of the rectorite nanosheet prepared in embodiment 2 of the invention is 5-10 nm, fig. 4 is a representation of the rectorite nanosheet rapidly collected by combining natural sedimentation and cation-assisted precipitation in embodiment 2 of the invention, a is a diagram of rapidly collecting the nanosheet by utilizing a polydiallyldimethylammonium chloride-assisted precipitation strategy, b is a diagram of the solid phase rectorite nanosheet (80g), and c is a tyndall effect of the rectorite nanosheet in different dispersion liquids.
Fig. 5 is a representation of the thickness of the rectorite nanosheet prepared in embodiment 2 of the present invention, where a is a photograph of an atomic force microscope of the rectorite nanosheet, and b is a thickness structure of the rectorite nanosheet, such that rapid and macro preparation of the rectorite nanosheet can be achieved.
Example 3 preparation of nacre-imitating rectorite nanosheet-aramid nanofiber insulation paper
Re-dispersing the solid-phase rectorite nanosheet prepared in example 2 in dimethyl sulfoxide, obtaining a uniform rectorite nanosheet dispersion liquid by ultrasound, then adding the rectorite nano dispersion liquid into an aramid nanofiber solution (containing dimethyl sulfoxide, aramid nanofibers, water and potassium hydroxide, wherein the mass concentration of the aramid nanofibers in the dimethyl sulfoxide is 1 wt.%, the mass ratio of the water to the potassium hydroxide is 4:1, and the using amount ratio of the water to the dimethyl sulfoxide is 10 g: 1L), and then obtaining a uniform mixed dispersion liquid by shearing, so as to regulate and control the content of the rectorite nanosheet (10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, respectively);
forming gel on the surface of a glass substrate by means of a spraying technology, then putting the gel into deionized water for soaking for 12 hours, and then drying for 48 hours under the normal temperature condition to obtain a composite film; and further soaking in deionized water for 12h, and drying at normal temperature for 48h to obtain the nacre-like rectorite nanosheet-aramid nanofiber insulating paper.
Due to the different proportions of the rectorite nanoplates, mechanical tensile tests (tensile tests on an Instron 5565A using a 500N weighing cell at a loading rate of 1mm min) were performed on the different composite films (nacre-imitated rectorite nanoplate-aramid nanofiber nanopaper) prepared in example 3-1At least six samples (. about.3 cm. times.3 mm. times.25 μm) were measured at a temperature of-25 ℃ and a relative humidity of-50%); as a result, it was found that when the content of the rectorite nanosheet is 20 wt.%, the mechanical properties are the best, with a tensile strength of 232MPa and a modulus of 3.8GPa (as shown by d in FIG. 6), and at the same time, 20 wt.% of the insulating paper has a good layered structure (as shown in b in fig. 6), 20 wt.% of the insulating paper also shows good stability in a high-temperature environment of 200-300 ℃ (as shown in e and f), fig. 6 is a performance characterization of the different proportions of the rectorite nanosheets-aramid nanofiber insulating paper prepared in example 3 of the present invention, a is a transmission microscope photograph of aramid nanofibers, b is a cross-sectional photograph of 20 wt.% of the rectorite nanosheets-aramid nanofiber paper, c is an optical photograph of the rectorite nanosheets-aramid nanofiber paper, d is the tensile strength and modulus of the different proportions of the rectorite, e is the tensile strength of 20 wt.% of the rectorite nanosheets-aramid nanofiber paper and the pure aramid nanofiber paper respectively treated at 200 ℃, 250 ℃, 300 ℃ for 24 hours, f is the modulus of 20 wt.% of rectorite nanosheet-aramid nanofiber paper and pure aramid nanofiber paper which are respectively treated at 200, 250 and 300 ℃ for 24 hours; it can be seen that 20 wt.% rectorite nanosheet-aramid nanofiber paper has optimal tensile strength and modulus, and these properties have good stability at high temperatures relative to pure aramid nanofiber paper.
Comparative example 1
An insulating paper was prepared according to the method of example 3, differing from example 2 in that no rectorite nanosheet was added to obtain a pure aramid nanofiber paper.
The mechanical properties of the pure aramid nanofiber paper prepared in comparative example 1 were tested according to the method of example 3, and the tensile stress and modulus were-160 MPa and-1.5 GPa, respectively, as shown in fig. 6 (d).
Performance detection
The electrical performance test (spraying gold on the insulation paper (25 μm), the breakdown strength being tested by a pressure tester (MS2677, china folk electronic limited) at room temperature) was performed on the rectorite nano-sheet-aramid nano-fiber insulation paper prepared in example 3, and the detection results are shown in fig. 7, where fig. 7 shows 20 wt.% of the rectorite nano-sheet-aramid nano-fiber nano-paper prepared in example 3 of the present invention, the pure aramid nano-fiber nano-paper prepared in comparative document 1, and 20 wt.% of the rectorite micro-sheet-aramid micro-fiber micro-paper (prepared according to the method of example 3 and implemented in the same manner as in the implementation of the method of example 3)Example 3 differs in replacing the rectorite nanosheets with rectorite nanoplatelets) breakdown strength, corona resistance and high temperature stability test results. The result shows that the 20 wt.% rectorite nanosheet-aramid nanofiber insulating paper has the best electrical insulating performance and the breakdown strength of 173kV mm-1The corona resistance time under 1000v and 10Hz was 35min, and in particular, the breakdown strength increased with increasing temperature and was 260kV mm at a treatment temperature of 300 deg.C-1And the breakdown strength of the pure aramid nano-fiber paper is 87kV mm-1The corona resistance time is 6min under the conditions of 1000v and 10Hz, and is far lower than 20 wt.% of rectorite nanosheet-aramid nanofiber insulating paper.
According to the invention, a polydiene dimethyl ammonium chloride-assisted precipitation strategy is used for replacing high-speed centrifugation, so that the effect of rapidly separating and stripping ultrathin rectorite nanosheets from a suspension is realized, and the prepared nacre-like structure rectorite nanosheet-aramid nanofiber composite material realizes excellent mechanical property, electrical insulation property and high-temperature stability.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
While the invention has been described and illustrated with reference to specific embodiments thereof, such description and illustration are not intended to limit the invention. It will be clearly understood by those skilled in the art that various changes in form and details may be made therein without departing from the true spirit and scope of the invention as defined by the appended claims, to adapt a particular situation, material, composition of matter, substance, method or process to the objective, spirit and scope of this application. All such modifications are intended to be within the scope of the claims appended hereto. Although the methods disclosed herein have been described with reference to particular operations being performed in a particular order, it should be understood that these operations may be combined, sub-divided, or reordered to form equivalent methods without departing from the teachings of the present disclosure. Accordingly, unless specifically indicated herein, the order and grouping of the operations is not a limitation of the present application.
Claims (10)
1. A method of making rectorite nanoplates comprising:
dispersing rectorite powder and polyvinylpyrrolidone in a solvent, stirring, and separating by adopting a natural sedimentation method to obtain a rectorite nanosheet suspension;
and collecting the rectorite nanosheets in the rectorite nanosheet suspension by adopting a cation-assisted precipitation method to obtain the rectorite nanosheets.
2. The method according to claim 1, wherein the solvent is selected from one or more of water, ethanol, isopropanol, N-dimethylformamide and dimethylsulfoxide.
3. The method of claim 1, wherein the mass ratio of the rectorite powder to the polyvinylpyrrolidone is (5-20) to (40-80).
4. The method according to claim 1, wherein the reagent used in the cation assisted precipitation process is one or more selected from polydiallyl dimethyl ammonium chloride and polyethylene imine.
5. The method according to claim 1, wherein the natural settling time is 1-10 hours.
6. The method of claim 1, wherein the volume ratio of the cationic dispersion to the suspension of rectorite nanosheets during the cation-assisted precipitation process is 1: (50-500).
7. An electrically insulating paper comprising: rectorite nanoplatelets prepared by the process of claim 1.
8. A method of making an electrically insulating paper comprising:
mixing a rectorite nanosheet solution and an aramid nanofiber solution to obtain a dispersion liquid;
spraying the dispersion liquid to obtain the electric insulating paper;
the solution of the rectorite nano-sheets contains the rectorite nano-sheets prepared by the method of claim 1.
9. The method of claim 8, wherein the aramid nanofiber solution comprises:
aramid fiber, water, potassium hydroxide and dimethyl sulfoxide.
10. The method according to claim 8, wherein the dispersion liquid contains 10 to 40% by mass of the rectorite nanosheets.
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