CN114572991B - Nano kaolin powder and preparation method thereof - Google Patents
Nano kaolin powder and preparation method thereof Download PDFInfo
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- CN114572991B CN114572991B CN202210262853.7A CN202210262853A CN114572991B CN 114572991 B CN114572991 B CN 114572991B CN 202210262853 A CN202210262853 A CN 202210262853A CN 114572991 B CN114572991 B CN 114572991B
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- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 title claims abstract description 233
- 239000005995 Aluminium silicate Substances 0.000 title claims abstract description 232
- 235000012211 aluminium silicate Nutrition 0.000 title claims abstract description 232
- 239000000843 powder Substances 0.000 title claims abstract description 150
- 238000002360 preparation method Methods 0.000 title claims abstract description 37
- 239000002002 slurry Substances 0.000 claims abstract description 100
- 239000002245 particle Substances 0.000 claims abstract description 43
- 238000001035 drying Methods 0.000 claims abstract description 36
- 238000005187 foaming Methods 0.000 claims abstract description 36
- 238000000227 grinding Methods 0.000 claims description 54
- 239000002270 dispersing agent Substances 0.000 claims description 34
- 238000003756 stirring Methods 0.000 claims description 30
- 239000003795 chemical substances by application Substances 0.000 claims description 23
- 239000003607 modifier Substances 0.000 claims description 22
- 238000004886 process control Methods 0.000 claims description 22
- 239000011248 coating agent Substances 0.000 claims description 21
- 238000000576 coating method Methods 0.000 claims description 21
- 239000011268 mixed slurry Substances 0.000 claims description 20
- 230000004048 modification Effects 0.000 claims description 20
- 238000012986 modification Methods 0.000 claims description 20
- 229920000142 Sodium polycarboxylate Polymers 0.000 claims description 17
- 239000004088 foaming agent Substances 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- WYTZZXDRDKSJID-UHFFFAOYSA-N (3-aminopropyl)triethoxysilane Chemical compound CCO[Si](OCC)(OCC)CCCN WYTZZXDRDKSJID-UHFFFAOYSA-N 0.000 claims description 13
- 229940051841 polyoxyethylene ether Drugs 0.000 claims description 13
- 229920000056 polyoxyethylene ether Polymers 0.000 claims description 13
- 238000002156 mixing Methods 0.000 claims description 12
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 9
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 8
- 239000007822 coupling agent Substances 0.000 claims description 8
- 150000002191 fatty alcohols Chemical class 0.000 claims description 8
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 8
- 235000011152 sodium sulphate Nutrition 0.000 claims description 8
- 239000000243 solution Substances 0.000 claims description 8
- 235000021355 Stearic acid Nutrition 0.000 claims description 7
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 claims description 7
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 claims description 7
- 239000007787 solid Substances 0.000 claims description 7
- 239000008117 stearic acid Substances 0.000 claims description 7
- 239000004115 Sodium Silicate Substances 0.000 claims description 6
- 239000008208 nanofoam Substances 0.000 claims description 6
- GCLGEJMYGQKIIW-UHFFFAOYSA-H sodium hexametaphosphate Chemical compound [Na]OP1(=O)OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])O1 GCLGEJMYGQKIIW-UHFFFAOYSA-H 0.000 claims description 6
- 235000019982 sodium hexametaphosphate Nutrition 0.000 claims description 6
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 6
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 6
- 235000019794 sodium silicate Nutrition 0.000 claims description 6
- 235000019832 sodium triphosphate Nutrition 0.000 claims description 6
- 239000001577 tetrasodium phosphonato phosphate Substances 0.000 claims description 6
- 239000002904 solvent Substances 0.000 claims description 5
- 239000006087 Silane Coupling Agent Substances 0.000 claims description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 4
- 150000004645 aluminates Chemical class 0.000 claims description 4
- 238000007865 diluting Methods 0.000 claims description 4
- 239000012267 brine Substances 0.000 claims description 3
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 23
- 238000005054 agglomeration Methods 0.000 abstract description 19
- 230000002776 aggregation Effects 0.000 abstract description 17
- 239000002105 nanoparticle Substances 0.000 abstract description 14
- 230000008569 process Effects 0.000 abstract description 9
- 239000007788 liquid Substances 0.000 abstract description 6
- 238000009776 industrial production Methods 0.000 abstract description 4
- 239000006185 dispersion Substances 0.000 description 18
- 230000004913 activation Effects 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 12
- 239000006260 foam Substances 0.000 description 10
- 239000000463 material Substances 0.000 description 10
- 239000002131 composite material Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- HQYALQRYBUJWDH-UHFFFAOYSA-N trimethoxy(propyl)silane Chemical compound CCC[Si](OC)(OC)OC HQYALQRYBUJWDH-UHFFFAOYSA-N 0.000 description 7
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 6
- 238000000713 high-energy ball milling Methods 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 5
- 238000010533 azeotropic distillation Methods 0.000 description 5
- 239000011734 sodium Substances 0.000 description 5
- 229910052708 sodium Inorganic materials 0.000 description 5
- PQUXFUBNSYCQAL-UHFFFAOYSA-N 1-(2,3-difluorophenyl)ethanone Chemical compound CC(=O)C1=CC=CC(F)=C1F PQUXFUBNSYCQAL-UHFFFAOYSA-N 0.000 description 4
- 238000010907 mechanical stirring Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 description 4
- 229940047670 sodium acrylate Drugs 0.000 description 4
- -1 sodium fatty alcohol Chemical class 0.000 description 4
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 239000011324 bead Substances 0.000 description 3
- 238000012512 characterization method Methods 0.000 description 3
- 239000004927 clay Substances 0.000 description 3
- 238000003801 milling Methods 0.000 description 3
- 239000011259 mixed solution Substances 0.000 description 3
- 238000007709 nanocrystallization Methods 0.000 description 3
- 239000011858 nanopowder Substances 0.000 description 3
- 238000001694 spray drying Methods 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 238000003921 particle size analysis Methods 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 208000002430 Multiple chemical sensitivity Diseases 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000012792 core layer Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 230000009969 flowable effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000007603 infrared drying Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 229910052622 kaolinite Inorganic materials 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000002715 modification method Methods 0.000 description 1
- 230000035772 mutation Effects 0.000 description 1
- 239000002101 nanobubble Substances 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000012763 reinforcing filler Substances 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000000935 solvent evaporation Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 239000013076 target substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/20—Silicates
- C01B33/36—Silicates having base-exchange properties but not having molecular sieve properties
- C01B33/38—Layered base-exchange silicates, e.g. clays, micas or alkali metal silicates of kenyaite or magadiite type
- C01B33/40—Clays
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/22—Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Nanotechnology (AREA)
- Dispersion Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Crystallography & Structural Chemistry (AREA)
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
Abstract
The invention relates to a nano kaolin powder and a preparation method thereof. According to the preparation method of the nano kaolin powder, the liquid of the slurry is converted into the critical state vapor film through the fine foaming process, the generated fine bubbles space the modified particles, the drying speed is greatly increased, the hard agglomeration of the nano particles in the drying process is effectively prevented, and the powder is easy to disperse to obtain the active nano kaolin powder. The method well solves the problem of hard agglomeration of the nano particles which is difficult to avoid in the drying process, and has the characteristics of simplicity, high efficiency and easy industrial production.
Description
Technical Field
The invention relates to the technical field of nano materials, in particular to nano kaolin powder and a preparation method thereof.
Background
The nanometer material is one material with three dimensional space scale in nanometer level (1 nm-100 nm), and is one new generation material comprising nanometer particles in size between atom, molecule and macroscopic system. As the size of the particles decreases to nanometer levels, new characteristics will be presented by acoustic, optical, electrical, magnetic or thermal properties. Nano kaolin is one member and has wide application in the modern industrial field. However, in a natural state, kaolinite particles are mutually adsorbed and connected to form an aggregate or an aggregate, so that the nanometer effect cannot be generated by direct application, and the particles are separated by adopting a proper method to form single nanometer particles, so that the nanometer mutation effect can be generated. Therefore, the kaolin needs to be nanocrystallized to endow the kaolin with various nano characteristics, so that the application value of the kaolin is greatly increased.
However, kaolin belongs to natural mineral materials, and is mainly ground and crushed to obtain nano slurry at present, but the application of kaolin is mainly dry powder application, so that the kaolin needs to be dried out of the slurry, and the problem of hard agglomeration is difficult to overcome in the drying process, so that the kaolin is not nano particles after drying, and the application value of the kaolin is seriously influenced. At present, the problem of hard agglomeration can be well solved by azeotropic distillation and the like, but the process method is difficult to leave a laboratory and cannot expand production; modified spray drying and the like have the characteristics of expanding production, but are not ideal for solving the problem of hard agglomeration.
Disclosure of Invention
Based on the above, it is necessary to provide a method for preparing nano kaolin powder which can solve the problem of hard agglomeration in the drying process and has the characteristics of industrial production.
In addition, a nano kaolin powder is also provided.
The preparation method of the nano kaolin powder comprises the following steps:
carrying out fine foaming treatment on the nano kaolin slurry subjected to surface coating modification so as to convert a solvent in the slurry into micro-nano foam, and dispersing the nano kaolin subjected to surface coating modification in the micro-nano foam;
drying the slurry after the fine foaming treatment to obtain loose kaolin blocks; and
Scattering the kaolin blocks to obtain the nano kaolin powder.
According to the preparation method of the nano kaolin powder, the liquid of the slurry is converted into the critical state vapor film through the fine foaming process, the generated fine bubbles space the modified particles, the drying speed is greatly increased, the hard agglomeration of the nano particles in the drying process is effectively prevented, and the powder is easy to disperse to obtain the active nano kaolin powder. The method well solves the problem of hard agglomeration of the nano particles which is difficult to avoid in the drying process, and has the characteristics of simplicity, high efficiency and easy industrial production.
In one embodiment, the step of fine foaming treatment comprises adding a foaming agent to the surface-coated modified nanokaolin slurry and stirring.
In one embodiment, the foaming agent comprises sodium fatty alcohol polyoxyethylene ether sulfate and gamma-aminopropyl triethoxysilane.
In one embodiment, the step of drying includes a thermal drying process.
In one embodiment, the preparation method further comprises the following steps of preparing the nano kaolin slurry subjected to surface coating modification:
mixing kaolin slurry, a grinding aid and a first dispersing agent to obtain first mixed slurry;
after primary grinding is carried out on the first mixed slurry, a modifier is added for secondary grinding, and nano kaolin slurry is obtained; and
Diluting the nano kaolin slurry by adopting a first process control agent, and then adding the modifier again for mixing to obtain the nano kaolin slurry with the surface coated and modified;
wherein the grinding aid comprises stearic acid, the first dispersant comprises at least one of sodium polycarboxylate, sodium tripolyphosphate, sodium hexametaphosphate, sodium silicate, sodium polyacrylate and sodium acrylate, the modifier comprises a titanate coupling agent, a silane coupling agent or an aluminate coupling agent, and the first process control agent comprises water.
In one embodiment, the grinding aid comprises 1 to 2wt% of the kaolin powder, the first dispersant comprises 0.5 to 1.0wt% of the kaolin powder, the modifier comprises 0.3 to 0.5wt% of the kaolin powder, and the solid content of the nano kaolin slurry diluted by the first process control agent is 30 to 50wt%.
In one embodiment, the grinding is performed in a high-energy ball mill at a rotational speed of 800RPM to 1200RPM, the primary grinding time is 2 hours to 4 hours, and the secondary grinding time is 1 hour to 2 hours.
In one embodiment, the above preparation method further comprises the following steps of preparing the kaolin slurry:
mixing a second dispersant and a second process control agent to obtain a brine solution; and
Adding kaolin powder into the saline solution under stirring to obtain second mixed slurry, and stirring to obtain kaolin slurry;
the second dispersant comprises at least one of sodium polycarboxylate, sodium tripolyphosphate, sodium hexametaphosphate, sodium silicate, sodium polyacrylate and sodium acrylate, the second process control agent comprises water, and the kaolin powder has a median particle size of 5-15 μm.
In one embodiment, the second dispersant comprises 0.5wt% to 1.0wt% of the mass of the kaolin powder, and the kaolin powder comprises 50wt% to 65wt% of the second mixed slurry.
A nano kaolin powder prepared according to any one of the preparation methods described in the above embodiments.
Drawings
FIG. 1 is a graph showing the particle size analysis of kaolin powder before and after high-energy ball milling in example 1;
fig. 2 (a) to (f) are graphs showing scanning electron microscope results of kaolin powders prepared in comparative examples 1, 2,3, 2 and 3, respectively.
Detailed Description
The following detailed description of the present invention will provide further details in order to make the above-mentioned objects, features and advantages of the present invention more comprehensible. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the invention, whereby the invention is not limited to the specific embodiments disclosed below.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The terms "first," "second," and the like, as used herein, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
An embodiment of the present invention provides a method for preparing a nano kaolin powder, which includes steps S001, S002 and S003, specifically:
step S001: and carrying out fine foaming treatment on the nano kaolin slurry subjected to surface coating modification so as to convert a solvent in the slurry into micro-nano foam, and dispersing the nano kaolin subjected to surface coating modification in the micro-nano foam.
Specifically, the surface coating modification is to treat the surface of the particles by a physical or chemical method, coat the surface of the particles by inorganic matters or organic matters, and introduce a coating layer on the surface of the particles, so that the powder after coating modification can be seen as composite powder consisting of a core layer and a shell layer. By coating a layer of coating layers with different components on the surface of the powder, the wetting and attaching characteristics of the powder can be changed, the dispersion behavior of the powder in a matrix can be improved, and the interface binding energy of the powder and the matrix can be improved. As used herein, "micro-nano-scale foam" refers to a dispersion of a large number of highly flowable and low density gases separated by a liquid, the gas in the dispersion being present in bubbles having diameters between hundreds of nanometers and tens of micrometers, such bubbles being between micro-bubbles and nano-bubbles.
In one embodiment, preparing the surface-coating-modified nanokaolin slurry includes step S011, step S012, and step S013, specifically:
step S011: mixing the kaolin slurry, the grinding aid and the first dispersant to obtain a first mixed slurry.
The grinding aid is used for improving grinding efficiency and is composed of one or more substances with surface activity and other chemical aids, the surface energy of grinding powder can be obviously reduced in the grinding process of materials, the attractive force between the grinding powder is overcome, the grinding resistance is reduced, ball pasting is prevented, the fluidity of the grinding powder is improved, the power consumption of the grinding machine is reduced, and the grinding efficiency is improved. In some embodiments, the grinding aid includes, but is not limited to, stearic acid. In an alternative specific example, the grinding aid is stearic acid.
In some embodiments, the grinding aid comprises 1wt% to 2wt% of the mass of the kaolin powder in the kaolin slurry. In an alternative specific example, the grinding aid comprises 1.2wt%, 1.4wt%, 1.5wt%, 1.6wt%, or 1.8wt% of the kaolin powder mass. Further, the grinding aid accounts for 1.1 to 1.9 weight percent of the mass of the kaolin powder. Further, the grinding aid accounts for 1.3 to 1.7 weight percent of the mass of the kaolin powder.
The first dispersing agent is used for stabilizing the state of the materials after finishing grinding and preparing dispersed uniform nano slurry. The dispersant adsorbs to the surface of the material particles and forms a considerable repulsive force between the material particles, which keeps the particles apart, reducing the tendency for uncontrolled flocculation. In some embodiments, the first dispersant comprises at least one of sodium polycarboxylate, sodium tripolyphosphate, sodium hexametaphosphate, sodium silicate, sodium polyacrylate, and sodium acrylate. In an alternative specific example, the first dispersant is sodium polycarboxylate.
In some embodiments, the first dispersant comprises from 0.5wt% to 1.0wt% of the mass of the kaolin powder in the kaolin slurry. In an alternative specific example, the first dispersant comprises 0.6wt%, 0.7wt%, 0.8wt%, or 0.9wt% of the kaolin powder mass. Further, the first dispersant accounts for 0.6wt% -0.9wt% of the mass of the kaolin clay powder. Still further, the first dispersant comprises 0.7wt% to 0.8wt% of the kaolin powder mass.
In one embodiment, the step of preparing the kaolin slurry comprises steps S111 and S112, in particular:
step S111: the second dispersant and the second process control agent are mixed to obtain a brine solution.
In some embodiments, the second dispersant comprises at least one of sodium polycarboxylate, sodium tripolyphosphate, sodium hexametaphosphate, sodium silicate, sodium polyacrylate, and sodium acrylate. It will be appreciated that the second dispersant is a dispersing agent and that the first dispersant may be the same as or different from the second dispersant in composition.
In some embodiments, the second dispersant comprises from 0.5wt% to 1.0wt% of the mass of the kaolin powder in the kaolin slurry. In an alternative specific example, the second dispersant comprises 0.6wt%, 0.7wt%, 0.8wt%, or 0.9wt% of the kaolin powder mass. In an alternative specific example, the second dispersant is sodium polycarboxylate.
In some embodiments, the second process control agent includes, but is not limited to, water. In an alternative specific example, the second process control agent is water.
In some embodiments, the second dispersant and the second process control agent are mixed and then stirred. Further, the second dispersant and the second process control agent are mixed and then mechanically stirred. Further, the mechanical stirring time is 1-2 h. In an alternative specific example, the mechanical agitation time is 1.2h, 1.4h, 1.5h, 1.6h, or 1.8h.
Step S112: adding the kaolin powder into the saline solution under stirring to obtain second mixed slurry, and stirring to obtain kaolin slurry.
In some embodiments, the kaolin powder has a median particle size of 5 μm to 15 μm. Further, the median particle diameter of the kaolin powder is 7 μm to 13. Mu.m. In an alternative specific example, the above-mentioned kaolin powder has a median particle size of 8 μm, 9 μm, 10 μm, 11 μm or 12 μm.
In some embodiments, the kaolin powder comprises 50wt% to 65wt% of the second mixed slurry. Further, the kaolin powder accounts for 52-63 wt% of the second mixed slurry. In an alternative specific example, the kaolin clay powder comprises 54wt%, 55wt%, 56wt%, 58wt%, 60wt%, or 62wt% of the second mixed slurry.
In some embodiments, the stirring time to obtain the kaolin slurry is from 4 hours to 8 hours. Further, the stirring time is 5-7 h. In an alternative specific example, the stirring time is 5.5 hours, 6 hours, or 6.5 hours.
Step S012: and (3) after primary grinding is carried out on the first mixed slurry, adding a modifier for secondary grinding, and obtaining the nano kaolin slurry.
In some embodiments, the modifying agent comprises a titanate coupling agent, a silane coupling agent, or an aluminate coupling agent. In an alternative specific example, the modifier is gamma- (2, 3-glycidoxy) propyltrimethoxysilane.
In some embodiments, the modifier comprises 0.3wt% to 1.0wt% of the kaolin powder mass. Further, the modifier accounts for 0.35 to 0.65 weight percent of the mass of the kaolin powder. In an alternative specific example, the modifier comprises 0.36wt%, 0.38wt%, 0.40wt%, 0.42wt%, 0.44wt%, 0.48wt%, or 0.50wt% of the kaolin powder mass.
In some embodiments, the milling is performed in a high energy ball mill at a rotational speed of 800RPM to 1200RPM, with a primary milling time of 2 hours to 4 hours and a secondary milling time of 1 hour to 2 hours. Further, the grinding is carried out in a high-energy ball mill at a rotating speed of 900-1100 RPM, the primary grinding time is 2.5-3.5 h, and the secondary grinding time is 1-2 h. Further, the grinding is performed in a high-energy ball mill at a rotational speed of 950RPM to 1050RPM, the primary grinding time is 2.5 to 3.5 hours, and the secondary grinding time is 1 to 2 hours.
The method adopts a wet stirring mill mode, and under the assistance of the grinding aid and the dispersing agent, the grinding medium and the kaolin powder particles are caused to perform actions of mutual impact, friction, collision and shearing, so that the effect of material nanocrystallization is rapidly achieved, and the powder material nanocrystallization can be efficiently and rapidly realized. Meanwhile, coating modification of powder particles is carried out in the grinding process, instantaneous heat energy is generated by utilizing high grinding energy, new interfaces are generated by grinding and crushing, and high-speed grinding and rotating particles are wound by a modifier polymer chain, so that highly-combined surface coating modification is realized.
Step S013: and diluting the nano kaolin slurry by adopting a first process control agent, and then adding a modifier again for mixing to obtain the surface-coated modified nano kaolin slurry.
In some embodiments, the first process control agent described above includes, but is not limited to, water. In an alternative specific example, the first process control agent is water.
In some embodiments, the solids content of the nanokaolin slurry diluted with the first process control agent is between 30wt% and 50wt%. Further, the solid content of the nano kaolin slurry diluted by the first process control agent is 30-45 wt%. Further, the solid content of the nano kaolin slurry diluted by the first process control agent is 35wt% to 40wt%.
In some embodiments, the modifier comprises 0.3wt% to 0.5wt% of the kaolin powder mass. Further, the modifier accounts for 0.35 to 0.45 weight percent of the mass of the kaolin powder. In an alternative specific example, the modifier comprises 0.36wt%, 0.38wt%, 0.40wt%, 0.42wt%, or 0.44wt% of the kaolin powder mass.
In some embodiments, the surface-coating-modified nanokaolin slurry is obtained by diluting the nanokaolin slurry with a first process control agent, adding the modifier again, mixing, and stirring. Further, stirring was performed using a high-speed stirrer. Further, stirring is performed at a speed of 5000RPM to 7000RPM by using a high-speed friction stirrer for 30min to 60min.
The coating rate of the particles is greatly improved by the secondary modification method, and the dispersibility of the powder particles is further improved.
According to the invention, the kaolin powder particles are rapidly nanocrystallized by high-energy ball milling and adding the grinding aid and the dispersing agent, the nano process is extremely efficient, and meanwhile, the coated modified nano kaolin slurry is prepared by coating modification, so that the nano powder particles have excellent dispersibility and uniformity.
In some embodiments, the step of fine foaming treatment includes adding a foaming agent to the surface-cladding-modified nanokaolin slurry and stirring. It will be appreciated that in some embodiments, other methods of fine foaming may be employed.
In some embodiments, dispersing the surface-coated modified nanokaolin in the micro-nanoscale foam after the fine foaming process means that more than 99% (v/v) of the solvent in the nanokaolin slurry is converted into the micro-nanoscale foam, the nanokaolin is trapped between bubbles, and adjacent nanoparticles are separated by bubbles.
Specifically, the foaming agent refers to a substance for forming pores of a target substance, and comprises three main types of chemical foaming agents, physical foaming agents and surfactants. It will be appreciated that any suitable foaming agent may be used for the fine foaming process. In some embodiments, the foaming agent comprises sodium fatty alcohol polyoxyethylene ether sulfate and gamma-aminopropyl triethoxysilane.
In one embodiment, the sodium fatty alcohol-polyoxyethylene ether sulfate accounts for 0.5 to 1.5 weight percent of the mass of the kaolin powder, and the gamma-aminopropyl triethoxysilane accounts for 0.5 to 1.5 weight percent of the mass of the kaolin. Further, the fatty alcohol polyoxyethylene ether sodium sulfate accounts for 0.6wt% -1.4wt% of the kaolin powder, and the gamma-aminopropyl triethoxysilane accounts for 0.6wt% -1.4wt% of the kaolin powder. In an alternative specific example, the sodium fatty alcohol polyoxyethylene ether sulfate comprises 0.7wt%, 0.9wt%, 1.0wt%, 1.1wt%, or 1.3wt% of the kaolin powder, and the gamma-aminopropyl triethoxysilane comprises 0.7wt%, 0.9wt%, 1.0wt%, 1.1wt%, or 1.3wt% of the kaolin powder. The aim of fine foaming can be better achieved by adopting sodium fatty alcohol polyoxyethylene ether sulfate and gamma-aminopropyl triethoxysilane with proper concentration.
In some embodiments, the foaming agent is added to the surface-coated modified nanokaolin slurry and then stirred using a high speed stirrer. Further, stirring is performed at a speed of 3000RPM to 5000RPM in a high-speed stirrer. Further, stirring was performed at 3500RPM to 4500RPM in a high-speed stirrer.
In an alternative specific example, the fatty alcohol polyoxyethylene ether sodium sulfate and the gamma-aminopropyl triethoxysilane are simultaneously added into the nano kaolin slurry subjected to surface coating modification and then stirred by a high-speed stirrer, or the fatty alcohol polyoxyethylene ether sodium sulfate is firstly added and then stirred by the high-speed stirrer, and then the gamma-aminopropyl triethoxysilane is added and then stirred by the high-speed stirrer. The researchers of the invention find that the purpose of fine foaming can be better achieved by adopting the two modes.
Particularly, researchers of the invention find that the micro-nano-scale foam generated after the fine foaming treatment has a large enough volume, has a certain strength, is stable and is not easy to collapse. The micro-nano-scale foam isolates the nano particles, so that the distance and difficulty of particle agglomeration in the drying process are greatly increased, meanwhile, the foaming can change the solvent of the slurry into a critical state vapor film, at the moment, all flowing liquid is changed into micro-foam, the drying specific surface area is greatly increased, and the solvent evaporation rate is greatly increased, so that the nano particles are not too long as the agglomeration is grown during drying. In addition, the foam with certain strength changes the flowing slurry into a solid state without flowing, the particles are fixed by the solid state, and migration and agglomeration can not occur during drying, so that the aim of obtaining the nano dry powder is fulfilled. The effect is best when the foam and powder particle sizes are close.
Step S002: and drying the slurry after the fine foaming treatment to obtain loose kaolin blocks.
In some embodiments, the step of drying includes a thermal drying process. Further, the manner of the heat drying treatment includes, but is not limited to, heat drying, microwave drying, infrared drying or flash drying. Further, the step of heat drying treatment comprises placing the slurry after the fine foaming treatment at 150-180 ℃ for 5-8 hours.
Specifically, the heat drying treatment can further foam the slurry subjected to the fine foaming treatment, convert the liquid of the slurry into a critical state vapor film, and the generated fine bubbles separate the modified particles, so that the drying speed is greatly increased, and the hard agglomeration is prevented.
Step S003: scattering the kaolin blocks to obtain the nano kaolin powder.
Specifically, the nano kaolin block after fine foaming and drying is a loose powder block, each particle in the nano kaolin block is coated by the modifier, and meanwhile, the particles are isolated by bubbles and are in a loose pseudo-agglomeration state and are easy to disperse, so that the nano kaolin powder is obtained.
In some embodiments, a high-speed crushing disperser is used to disperse the bulk kaolin clay mass. Further, the loose kaolin blocks are dispersed by a high-speed crushing and dispersing machine at a speed of 6000 RPM-8000 RPM, and the total dispersing time is 25 s-35 s. Further, the loose kaolin blocks are dispersed by a high-speed crushing and dispersing machine at the speed of 6000-8000 RPM, wherein the total dispersing time is 30s, and the loose kaolin blocks are divided into 3 times, 10s each time, and 1-2 min each time interval.
According to the preparation method of the nano kaolin powder, the liquid of the slurry is converted into the critical state vapor film through the fine foaming process, the generated fine bubbles space the modified particles, the drying speed is greatly increased, the hard agglomeration of the nano particles in the drying process is effectively prevented, and the powder is easy to disperse to obtain the active nano kaolin powder. The method well solves the problem of hard agglomeration of the nano particles which is difficult to avoid in the drying process, and has the characteristics of simplicity, high efficiency and easy industrial production.
The invention also provides a nano kaolin powder, which is prepared by the preparation method according to any embodiment.
In some embodiments, the nanokaolin powder is in the form of platelet aggregates having a diameter of 0.5 μm to 2 μm due to surface tension and electrostatic effects. Further, the nano kaolin powder is a flaky aggregate with a median diameter of 0.8-1.2 μm due to surface tension and electrostatic effect.
In some embodiments, the dispersion rate of the nano kaolin powder is 95% -98%.
In some embodiments, the nano kaolin powder has an activation index of 99% or more.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The following is a detailed description of specific embodiments. The following examples are not specifically described but do not include other components than the unavoidable impurities. Reagents and apparatus used in the examples, unless otherwise specified, are all routine choices in the art. The experimental methods without specific conditions noted in the examples were carried out according to conventional conditions, such as those described in the literature, books, or recommended by the manufacturer.
Example 1
1. Preparation of kaolin slurry
(1) Preparation of saline solution
Water and 0.8wt% sodium polycarboxylate of kaolin powder were mixed and mechanically stirred for 1.5h to obtain a sodium polycarboxylate solution.
(2) Preparation of kaolin slurry
Gradually adding kaolin powder with the median particle size of 5-15 μm into the prepared saline solution under mechanical stirring to obtain a mixed solution with the kaolin powder accounting for 55wt% and stirring for 6h to obtain the kaolin slurry. The kaolin slurry was analyzed by particle size testing using a laser particle sizer (Mastersizer 3000,Malvern Panalytical, uk) and the results are shown in figure 1.
2. Preparation of modified nano kaolin slurry
(1) The kaolin slurry was added to a high energy ball mill (SuperFlow 12, buhler, switzerland) at one time, and zirconia beads having a diameter of 0.5mm and a purity of 99%, stearic acid 1.5wt% based on the mass of the kaolin powder, and sodium polycarboxylate 0.8wt% were added at the same time, to obtain a mixed slurry.
(2) Grinding the mixed slurry in a high-energy ball mill at a speed of 1000RPM for 3 hours, adding gamma- (2, 3-glycidoxy) propyl trimethoxy silane (KH 560) accounting for 0.40 weight percent of the mass of the kaolin powder, and grinding for 1 hour to obtain modified nano kaolin slurry A. Particle size analysis was performed on the modified nanokaolin slurry a, and the results are shown in fig. 1.
(3) Adding water to dilute the modified nano kaolin slurry A until the volume of the kaolin is 40% of the total mass of the slurry, then adding gamma- (2, 3-glycidoxy) propyl trimethoxy silane (KH 560) accounting for 0.40wt% of the mass of the kaolin powder, stirring for 40min at 5500RPM in a high-speed friction stirring machine (model: SDF-400), and carrying out secondary coating modification to obtain modified nano kaolin slurry B.
3. Preparation of bulk kaolin blocks
(1) Adding a composite foaming agent into the modified nano kaolin slurry B, wherein the composite foaming agent is formed by mixing fatty alcohol polyoxyethylene ether sodium sulfate accounting for 1.0wt% of the mass of kaolin powder and gamma-aminopropyl triethoxysilane (KH 550) accounting for 1.0wt%, and stirring the mixture at the speed of 4000RPM in a high-speed stirrer for fine foaming treatment.
(2) The slurry after the fine foaming treatment was added to a constant temperature bellows for 6 hours, subjected to further thermal foaming treatment at 160 ℃ and dried to obtain a bulk kaolin block.
4. Preparation of nano kaolin powder
The loose kaolin blocks are dispersed by a high-speed dispersing machine (model: RT-N04) at the speed of 7000RPM, the total dispersing time is 30s, the dispersing time is divided into 3 times, each time is 10s, and each time is separated by 1 min-2 min, so that the nano kaolin powder is obtained. The morphology of the nano kaolin powder obtained by scanning electron microscope photographing is shown in fig. 2 (b).
5. Determination of the Dispersion and activation index of the Nano Kaolin powder
The dispersion rate of the prepared nano kaolin powder is measured by a dispersion rate characterization method, the activation index of the prepared nano kaolin powder is measured according to the definition of the activation index, and the result is shown in table 1.
Example 2
1. Preparation of kaolin slurry
(1) Preparation of saline solution
Water and 0.5wt% sodium polycarboxylate of kaolin powder were mixed and mechanically stirred for 1h to obtain a sodium polycarboxylate solution.
(2) Preparation of kaolin slurry
Gradually adding kaolin powder with the median particle size of 5-15 μm into the prepared saline solution under mechanical stirring to obtain a mixed solution with the kaolin powder accounting for 60wt% and stirring for 8 hours to obtain the kaolin slurry.
2. Preparation of modified nano kaolin slurry
(1) The kaolin slurry was added to a high energy ball mill (SuperFlow 12, buhler, switzerland) at one time, and zirconia beads having a diameter of 0.5mm and a purity of 99%, stearic acid accounting for 1.0wt% of the mass of the kaolin powder, and sodium polycarboxylate were added at the same time to obtain a mixed slurry.
(2) Grinding the mixed slurry in a high-energy ball mill at a speed of 1000RPM for 2.5h, adding gamma- (2, 3-glycidoxy) propyl trimethoxy silane (KH 560) accounting for 0.50wt% of the mass of the kaolin powder, and grinding for 1h to obtain modified nano kaolin slurry A.
(3) Adding water to dilute the modified nano kaolin slurry A until the volume of the kaolin is 30% of the total mass of the slurry, then adding gamma- (2, 3-glycidoxy) propyl trimethoxy silane (KH 560) accounting for 0.50wt% of the mass of the kaolin powder, stirring for 30min at a speed of 5000RPM in a high-speed friction stirring machine (model: SDF-400), and carrying out secondary coating modification to obtain the modified nano kaolin slurry B.
3. Preparation of bulk kaolin blocks
(1) Adding a composite foaming agent into the modified nano kaolin slurry B, wherein the composite foaming agent is formed by mixing fatty alcohol polyoxyethylene ether sodium sulfate accounting for 0.5wt% of the mass of kaolin powder and gamma-aminopropyl triethoxysilane (KH 550) accounting for 1.0wt%, and stirring the mixture at a speed of 5000RPM in a high-speed stirrer for fine foaming treatment.
(2) The slurry after the fine foaming treatment is added into a constant temperature bellows for 8 hours, and further heat foaming treatment is carried out at 150 ℃ and drying is carried out to obtain loose kaolin blocks.
4. Preparation of nano kaolin powder
Dispersing the loose kaolin blocks by a high-speed dispersing machine (model: RT-N04) at a speed of 6000RPM for 30s, wherein the total dispersing time is divided into 3 times, 10s each time and 1-2 min each time, and obtaining the nano kaolin powder. The morphology of the nano kaolin powder obtained by scanning electron microscope photographing is shown in fig. 2 (c).
5. Determination of the Dispersion and activation index of the Nano Kaolin powder
The dispersion rate of the prepared nano kaolin powder is measured by a dispersion rate characterization method, the activation index of the prepared nano kaolin powder is measured according to the definition of the activation index, and the result is shown in table 1.
Example 3
1. Preparation of kaolin slurry
(1) Preparation of saline solution
Water and 1.0wt% sodium polycarboxylate of kaolin powder were mixed and mechanically stirred for 2 hours to obtain a sodium polycarboxylate solution.
(2) Preparation of kaolin slurry
Gradually adding kaolin powder with the median particle size of 5-15 μm into the prepared saline solution under mechanical stirring to obtain a mixed solution with the kaolin powder accounting for 65wt% and stirring for 8 hours to obtain the kaolin slurry.
2. Preparation of modified nano kaolin slurry
(1) The kaolin slurry was added to a high energy ball mill (SuperFlow 12, buhler, switzerland) at one time, and zirconia beads having a diameter of 0.5mm and a purity of 99%, stearic acid 1.5% by weight based on the mass of the kaolin powder, and sodium polycarboxylate 1.0% by weight were added at the same time, to obtain a mixed slurry.
(2) Grinding the mixed slurry in a high-energy ball mill at a speed of 1200RPM for 4 hours, adding gamma- (2, 3-glycidoxy) propyl trimethoxy silane (KH 560) accounting for 1.0wt% of the mass of the kaolin powder, and grinding for 1 hour to obtain modified nano kaolin slurry A.
(3) Adding water to dilute the modified nano kaolin slurry A until the volume of the kaolin is 35% of the total mass of the slurry, then adding gamma- (2, 3-glycidoxy) propyl trimethoxy silane (KH 560) accounting for 0.50wt% of the mass of the kaolin powder, stirring for 60min at 7000RPM in a high-speed friction stirring machine (model: SDF-400), and carrying out secondary coating modification to obtain the modified nano kaolin slurry B.
3. Preparation of bulk kaolin blocks
(1) Adding a composite foaming agent into the modified nano kaolin slurry B, wherein the composite foaming agent is formed by mixing fatty alcohol polyoxyethylene ether sodium sulfate accounting for 0.5wt% of the mass of kaolin powder and gamma-aminopropyl triethoxysilane (KH 550) accounting for 1.5wt%, and stirring the mixture at a speed of 5000RPM in a high-speed stirrer for fine foaming treatment.
(2) The finely foamed slurry was added to a constant temperature bellows for 7 hours, subjected to further thermal foaming at 170 ℃ and dried to obtain a bulk kaolin block.
4. Preparation of nano kaolin powder
Dispersing the loose kaolin blocks by a high-speed dispersing machine (model: RT-N04) at a speed of 6000RPM for 30s, wherein the total dispersing time is divided into 3 times, 10s each time and 1-2 min each time, and obtaining the nano kaolin powder. The morphology of the nano kaolin powder obtained by scanning electron microscope photographing is shown in fig. 2 (d).
5. Determination of the Dispersion and activation index of the Nano Kaolin powder
The dispersion rate of the prepared nano kaolin powder is measured by a dispersion rate characterization method, the activation index of the prepared nano kaolin powder is measured according to the definition of the activation index, and the result is shown in table 1.
Comparative example 1
This comparative example is substantially the same as the preparation procedure of example 1, except that the modified nanokaolin slurry B obtained in step 2 is directly subjected to a drying treatment and dispersed without performing a fine foaming treatment. The morphology of the nano kaolin powder obtained by scanning electron microscope photographing is shown in fig. 2 (a). The dispersion and activation index of the prepared kaolin powder are shown in table 1.
Comparative example 2
This comparative example is substantially the same as the preparation step of example 1 except that the fine foaming treatment is not performed in the step 3 of this comparative example, and the modified nanokaolin slurry B is dried by a spray drying method. The morphology of the nano kaolin powder obtained by scanning electron microscope photographing is shown in fig. 2 (c). The dispersion and activation index of the prepared kaolin powder are shown in table 1.
Comparative example 3
This comparative example was substantially the same as the preparation step of example 1, except that the fine foaming treatment was not performed in the step 3 of this comparative example, and the modified nanokaolin slurry B was dried by an azeotropic distillation method. The morphology of the nano kaolin powder obtained by scanning electron microscope photographing is shown in fig. 2 (d). The dispersion and activation index of the prepared kaolin powder are shown in table 1.
Analysis of results
In FIG. 1, "Kaolin raw powders" represents Kaolin particles that have not been subjected to high energy ball milling, and "Kaolin nano-porous" represents Kaolin particles that have been subjected to high energy ball milling. From the results of fig. 1, it is apparent that the particle size of the kaolin particles subjected to the high-energy ball milling is almost uniformly distributed below 0.2 μm, indicating that the high-energy ball milling can effectively promote the nanocrystallization of the kaolin particles.
The scanning electron microscope result of the nano kaolin powder according to fig. 2 shows that the kaolin particles (fig. 2 (a)) of comparative example 1, which were directly dried without fine foaming treatment, have large lump-shaped agglomerates, poor dispersion uniformity, and a maximum agglomeration diameter of about 7 μm. In this dry state, the agglomerates are less likely to be crushed into fine powder because hard agglomeration of the powder has occurred.
Whereas the results of the examples (FIGS. 2 (b-d)) show that there are a large number of fine clusters composed of nanoparticles of uniform size, without the presence of oversized agglomerates, the diameter of the platelet agglomerates being 0.5 μm to 2. Mu.m. The actual size of the dried kaolin nano-powder should be much smaller than that seen from the loose appearance of each cluster. The fine foam dried sample was good in dispersibility and uniformity, similar to the sample obtained by the azeotropic distillation method in comparative example 3 (fig. 2 (f)). Both present uniformly dispersed platelet-structured nanoparticle clusters, which are formed by pseudo-agglomeration of a large number of kaolin nanoparticles due to the strong surface tension of the kaolin nanoparticles in air and the electrostatic effect. The thickness of each sheet structure is ultra-thin on the nanometer scale. The azeotropic distillation samples had a thinner sheet structure, while the finely foamed samples had better uniformity. The results of comparative example 2 (FIG. 2 (e)) show that spray-dried samples exhibited a large number of spherical hard agglomerates ranging in diameter from 1 μm to 6 μm and had poor dispersibility and uniformity.
TABLE 1
According to the results in Table 1, the dispersion rate and the activation index of the nano kaolin powder prepared by the method are far higher than those of the nano kaolin powder which is not subjected to fine foaming treatment and the nano kaolin powder which is subjected to spray drying treatment, so that the excellent performance similar to that of the nano kaolin powder prepared by an azeotropic distillation method can be achieved, the preparation process is simpler, and the cost is lower.
The kaolin powder prepared by the method reaches the nanoscale, has excellent performance, skillfully solves the problem of serious hard agglomeration of the dry powder obtained by drying the nano powder from slurry, has good powder uniformity and dispersibility, high activation index and wide application, greatly improves the performance of the composite material when used as the nano reinforcing filler, and has wide application prospect.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. It should be understood that, based on the technical solutions provided by the present invention, those skilled in the art can obtain technical solutions through logical analysis, reasoning or limited experiments, which are all within the scope of protection of the appended claims. The scope of the invention is therefore intended to be covered by the appended claims, and the description and drawings may be interpreted in accordance with the contents of the claims.
Claims (2)
1. The preparation method of the nano kaolin powder is characterized by comprising the following steps:
carrying out fine foaming treatment on the nano kaolin slurry subjected to surface coating modification so as to convert a solvent in the slurry into micro-nano foam, and dispersing the nano kaolin subjected to surface coating modification in the micro-nano foam; drying the slurry after the fine foaming treatment to obtain loose kaolin blocks; scattering the kaolin blocks to obtain nano kaolin powder;
the preparation method of the nano kaolin slurry subjected to surface coating modification comprises the following steps:
(1) Mixing kaolin slurry, a grinding aid and a first dispersing agent to obtain first mixed slurry;
the steps for preparing the kaolin slurry include:
(i) Mixing a second dispersant and a second process control agent to obtain a brine solution;
(ii) Adding kaolin powder into the saline solution under stirring to obtain second mixed slurry, and stirring to obtain kaolin slurry;
wherein the second dispersant comprises at least one of sodium polycarboxylate, sodium tripolyphosphate, sodium hexametaphosphate and sodium silicate, the second process control agent comprises water, the second dispersant accounts for 0.5-1.0 wt% of the mass of the kaolin powder, the kaolin powder accounts for 50-65 wt% of the second mixed slurry, and the median particle size of the kaolin powder is 5-15 mu m;
the grinding aid comprises stearic acid, and the first dispersing agent comprises at least one of sodium polycarboxylate, sodium tripolyphosphate, sodium hexametaphosphate and sodium silicate; the grinding aid accounts for 1-2 wt% of the mass of the kaolin powder in the kaolin slurry, and the first dispersing agent accounts for 0.5-1.0 wt% of the mass of the kaolin powder;
(2) After primary grinding is carried out on the first mixed slurry, adding a modifier for secondary grinding to obtain nano kaolin slurry, wherein the grinding is carried out in a high-energy ball mill at a rotating speed of 800-1200 RPM, the primary grinding time is 2-4 h, and the secondary grinding time is 1-2 h;
wherein the modifier comprises a titanate coupling agent, a silane coupling agent or an aluminate coupling agent, and the modifier accounts for 0.3-1.0 wt% of the kaolin powder;
(3) Diluting the nano kaolin slurry by adopting a first process control agent, and then adding the modifier again for mixing to obtain the nano kaolin slurry subjected to surface coating modification;
wherein the modifier comprises a titanate coupling agent, a silane coupling agent or an aluminate coupling agent, and the modifier accounts for 0.3-0.5 wt% of the kaolin powder; the first process control agent comprises water, and the solid content in the nano kaolin slurry diluted by the first process control agent is 30-50wt%;
the fine foaming treatment comprises the steps of adding a foaming agent into the nano kaolin slurry subjected to surface coating modification, and stirring, wherein the foaming agent comprises fatty alcohol polyoxyethylene ether sodium sulfate and gamma-aminopropyl triethoxysilane, the fatty alcohol polyoxyethylene ether sodium sulfate accounts for 0.5-1.5 wt% of the kaolin powder, and the gamma-aminopropyl triethoxysilane accounts for 0.5-1.5 wt% of the kaolin powder;
the step of drying treatment includes a heat drying treatment including: and placing the slurry after the fine foaming treatment in 150-180 ℃ for 5-8 h.
2. A nano kaolin powder prepared according to the preparation method of claim 1.
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