CN115231593A - Method for preparing hexagonal magnesium hydroxide flame retardant by one-step hydrothermal method - Google Patents
Method for preparing hexagonal magnesium hydroxide flame retardant by one-step hydrothermal method Download PDFInfo
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- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 title claims abstract description 69
- 239000000347 magnesium hydroxide Substances 0.000 title claims abstract description 67
- 229910001862 magnesium hydroxide Inorganic materials 0.000 title claims abstract description 67
- 238000001027 hydrothermal synthesis Methods 0.000 title claims abstract description 36
- 239000003063 flame retardant Substances 0.000 title claims abstract description 21
- 238000000034 method Methods 0.000 title claims abstract description 20
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 title claims abstract description 19
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims abstract description 54
- 235000019270 ammonium chloride Nutrition 0.000 claims abstract description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 25
- 238000003756 stirring Methods 0.000 claims abstract description 24
- 239000000725 suspension Substances 0.000 claims abstract description 21
- 238000001914 filtration Methods 0.000 claims abstract description 19
- 238000005406 washing Methods 0.000 claims abstract description 17
- 238000001035 drying Methods 0.000 claims abstract description 16
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 13
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 13
- 230000001788 irregular Effects 0.000 claims abstract description 8
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 7
- 238000006243 chemical reaction Methods 0.000 claims abstract description 6
- 238000002156 mixing Methods 0.000 claims abstract description 3
- 239000002244 precipitate Substances 0.000 claims abstract description 3
- 239000000243 solution Substances 0.000 claims abstract 7
- 239000011259 mixed solution Substances 0.000 claims abstract 4
- 239000012153 distilled water Substances 0.000 claims description 20
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 claims description 2
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 2
- 238000003825 pressing Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 7
- 238000005265 energy consumption Methods 0.000 abstract description 3
- 230000008569 process Effects 0.000 abstract description 3
- 239000010865 sewage Substances 0.000 abstract description 2
- 230000009286 beneficial effect Effects 0.000 abstract 1
- 239000007788 liquid Substances 0.000 abstract 1
- 238000000926 separation method Methods 0.000 abstract 1
- 239000000843 powder Substances 0.000 description 37
- 239000002245 particle Substances 0.000 description 32
- 239000013078 crystal Substances 0.000 description 25
- 239000000047 product Substances 0.000 description 12
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 10
- 238000001816 cooling Methods 0.000 description 10
- 230000007613 environmental effect Effects 0.000 description 10
- 239000011777 magnesium Substances 0.000 description 10
- 229910052749 magnesium Inorganic materials 0.000 description 10
- 230000005540 biological transmission Effects 0.000 description 9
- 238000000227 grinding Methods 0.000 description 9
- 238000010438 heat treatment Methods 0.000 description 9
- 239000006185 dispersion Substances 0.000 description 7
- 229920001971 elastomer Polymers 0.000 description 5
- 239000005060 rubber Substances 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 239000004800 polyvinyl chloride Substances 0.000 description 4
- 229920000915 polyvinyl chloride Polymers 0.000 description 4
- -1 chemical engineering Substances 0.000 description 3
- 238000003889 chemical engineering Methods 0.000 description 3
- 239000003973 paint Substances 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
- 239000002861 polymer material Substances 0.000 description 3
- 239000004698 Polyethylene Substances 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005065 mining Methods 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- 229920006305 unsaturated polyester Polymers 0.000 description 2
- 229920002943 EPDM rubber Polymers 0.000 description 1
- 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
- 239000004793 Polystyrene Substances 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000004676 acrylonitrile butadiene styrene Substances 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 229920005669 high impact polystyrene Polymers 0.000 description 1
- 239000004797 high-impact polystyrene Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229920001707 polybutylene terephthalate Polymers 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F5/00—Compounds of magnesium
- C01F5/14—Magnesium hydroxide
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
- C09C1/02—Compounds of alkaline earth metals or magnesium
- C09C1/028—Compounds containing only magnesium as metal
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
-
- 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
- C01P2006/12—Surface area
-
- 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
- C01P2006/80—Compositional purity
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention provides a method for preparing hexagonal magnesium hydroxide flame retardant by a one-step hydrothermal method, which comprises the steps of mixing irregular magnesium hydroxide, ammonium chloride and water to obtain a mixed solution, adding the mixed solution into a closed hydrothermal reaction kettle, stirring at a constant temperature of 40-100 ℃ for 0.5-2 hours to obtain a magnesium hydroxide dissolved solution, dropwise adding an ammonia water solution with a mass concentration of 10-20% until the pH of the reaction solution is 8-10, stopping dropwise adding, stirring at the constant temperature for 2-3 hours to obtain a suspension, standing for 1 hour, filtering, washing, drying and crushing a precipitate to obtain the hexagonal magnesium hydroxide flame retardant. The method of the invention has the following beneficial effects: (1) The irregular magnesium hydroxide is modified into hexagonal magnesium hydroxide by a one-step method, so that the form of the magnesium hydroxide is improved, the modified process flow is reduced, the production efficiency is improved, and the energy consumption is reduced; (2) The synthesized magnesium hydroxide has a regular structure, the surface area is reduced, and the dispersibility is improved; (3) The separation liquid can be recycled after the PH is adjusted, the cost is reduced, no sewage is discharged, and the method is safe and environment-friendly.
Description
Technical Field
The invention relates to a method for preparing a hexagonal magnesium hydroxide flame retardant by a one-step hydrothermal method.
Background
With the wide application of high molecular polymer materials in the fields of construction, traffic, electricity and the like, in which fire easily occurs under the conditions of high pressure, heat generation, power generation and the like, and a large amount of toxic gas and smoke are released during combustion, a large amount of casualties and huge property loss are caused, and the problems directly promote the research, development and production of flame retardant magnesium hydroxide.
Magnesium hydroxide is widely used in the industrial fields of PE, PP, PVC, ABS, PS, HIPS, PA, PBT, unsaturated polyester, epoxy resin, rubber, flame-retardant filler of paint, chemical engineering, environmental protection and the like; used as excellent flame retardant and filler for high molecular material such as plastic and rubber. Wherein the weight ratio of common magnesium hydroxide: the method is applied to the industries of rubber, plastics, paint, coating, chemical engineering and the like. Active magnesium hydroxide: the active magnesium hydroxide fire retardant is widely applied to high polymer materials such as rubber, chemical engineering, building materials, plastics (polypropylene, polyethylene, polyvinyl chloride and ethylene propylene diene monomer) and electronics, unsaturated polyester, paint, coating and the like, particularly has flame retardance, smoke abatement and antistatic effects on mining air duct coating cloth, PVC whole core conveyor belt, flame-retardant rubber plate, tarpaulin, PVC wire and cable materials, mining cable sheath and cable accessories, can replace aluminum hydroxide, and has excellent flame retardant effect.
Magnesium hydroxide has many advantages, but dispersion and compatibility problems during synthetic production are also important factors affecting product performance. The normally synthesized magnesium hydroxide suffers from the following problems: (1) The crystal structure is incomplete in growth, poor in surface polarity and easy to agglomerate; (2) The filtering is slow, the drying energy consumption is large, and secondary agglomeration is easy to occur in the drying process; (3) Wide particle size distribution, poor dispersion and unstable application performance; the above problems seriously affect the performance of magnesium hydroxide in the application of high polymer materials, and the problems of dispersion, particle size and the like seriously affect the flame retardant performance and the addition proportion under the condition of meeting the requirements of flame retardant grade and performance.
The generation of magnesium hydroxide crystal grains comprises two aspects of crystal nucleation and production, the growth and nucleation of the commonly synthesized magnesium hydroxide crystal are inconsistent, and irregular shapes are easy to form, so that the magnesium hydroxide has higher surface energy, poor dispersion and easy agglomeration. The dispersibility and particle size distribution of magnesium hydroxide can be improved by external mechanical actions such as supergravity, an ultrasonic method, a microwave method and the like, but the improvement on the particle size surface is limited, and a further surface modification process is needed for obtaining the magnesium hydroxide flame retardant with excellent performance parameters.
Disclosure of Invention
The invention aims to provide a preparation method for producing a high-purity regular magnesium hydroxide flame retardant, which is simple, low in cost, high in product purity, regular in appearance and good in application dispersion.
The technical scheme of the invention is a method for preparing hexagonal magnesium hydroxide flame retardants by a one-step hydrothermal method, which comprises the following steps:
(1) Mixing irregular magnesium hydroxide, ammonium chloride and water
Obtaining mixed liquor, adding the mixed liquor into a closed hydrothermal reaction kettle, and stirring at the constant temperature of 40-100 ℃ for 0.5-2 hours to obtain a magnesium ion dissolved solution, wherein the dosage ratio of the irregular magnesium hydroxide, the ammonium chloride and the water is as follows: 50g-150g:250g-350g:2L-3L;
(2) And (2) dropwise adding the solution obtained in the step (1) into an ammonia water solution with the mass concentration of 10% -20% until the pH of the reaction solution is 8-10, stopping dropwise adding, stirring at a constant temperature for 2-3 hours to obtain a suspension, standing for 1 hour, filtering and washing a precipitate, and drying to obtain the hexagonal magnesium hydroxide flame retardant.
The method is carried out under the conditions of constant temperature and constant pressure, the used equipment is a closed reaction kettle, and the temperature is controlled during operation.
The magnesium hydroxide is high-purity chemical method magnesium synthesized conventionally, and the content of the magnesium hydroxide is more than 99%.
The ammonium chloride is refined ammonium chloride, low in potassium and sodium and 99.8 percent in content.
The temperature of the reaction kettle in the step (2) is 100-150 ℃.
The filtration washing is a conventional method, and the filtration washing steps of the invention are as follows: after the hydrothermal modification, cooling, filtering to obtain filter pressing, washing to obtain distilled water, drying at 105 ℃, preferably selecting flash evaporation equipment, and crushing to obtain a millstone type crusher to obtain the magnesium hydroxide flame retardant
According to the invention, the high-purity and high-dispersion magnesium hydroxide is prepared, the particle size of the product is tested to be 0.1-1.5um, the specific surface area is tested to be 6-15 m/g, the purity is more than 99.2%, and the crystal is in a hexagonal plate structure.
The invention is best embodied in that: (1) The hydrothermal modification of the magnesium hydroxide is completed in one step, so that the process flow is reduced, the production efficiency is improved, the modification temperature is low, the time is short, and the energy consumption is reduced; (2) The magnesium hydroxide dissolved and recrystallized has high crystallinity, regular appearance, uniform particle size, small specific surface area, good dispersion and easy filtration; (3) The production process is in a closed reaction kettle, the pH value is adjusted when the production process is finished, the ammonia water is fully utilized and is not leaked, no environmental pollution is ensured, the filtered ammonium chloride solution can be continuously utilized, no sewage is discharged, and the cost and the environmental pollution are reduced.
(IV) description of the drawings
FIG. 1 example two (80 ℃) hydrothermally modifies the appearance of magnesium hydroxide particles;
FIG. 2 example III (100 ℃ C.) hydrothermally modifying the appearance of magnesium hydroxide particles;
FIG. 3 example four (120 ℃ C.) hydrothermally modifying the appearance of magnesium hydroxide particles;
FIG. 4 example five (150 ℃ C.) hydrothermally modifying the appearance of magnesium hydroxide particles;
FIG. 5 example six (10% ammonia) hydrothermally modifying the appearance of magnesium hydroxide particles;
FIG. 6 example seven (20% ammonia) hydrothermally modified magnesium hydroxide particles appearance;
FIG. 7 example eight (2 h) hydrothermally modifying the appearance of magnesium hydroxide particles;
FIG. 8 example nine (4 h) hydrothermally modifying the appearance of magnesium hydroxide particles;
FIG. 9 XRD pattern of hydrothermally modified magnesium hydroxide of example four (120 ℃);
(V) detailed description of the preferred embodiments
The following further description of the present technology is provided in connection with specific embodiments, and the scope of the present invention is not limited to the following.
Example one
Dissolving 200g of ammonium chloride (environmental protection and practical industry Co., ltd., hunan, jianghai) in 3L of distilled water to obtain an ammonium chloride solution, adding 100g of magnesium hydroxide powder (325 meshes in Western magnesium), preparing a suspension, adding the prepared suspension into a hydrothermal reaction kettle, stirring and heating to 60 ℃, keeping the temperature constant for 3 hours, dropwise adding a 15% ammonia water solution into the hydrothermal reaction kettle by a high-pressure pump, stopping adding when the pH in the hydrothermal reaction kettle reaches 10, stirring at constant temperature for 3 hours, cooling, filtering, washing (distilled water), drying the obtained product at 105 ℃, crushing and grinding to obtain white powder. Observing the particle diameter, the morphology and the powder structure of the sample by a transmission electron microscope (SEM)Similar to hexagonal tablet, the purity is higher than 99%, the crystal particle size is mainly distributed in 400-800nm, the crystal thickness is mainly distributed in 20-60nm, and the specific surface area is 6-14m 2 And/g, the powder is easy to agglomerate and is not easy to filter, wash and dry.
Example two
Dissolving 200g of ammonium chloride (environmental protection and practical industry Co., ltd., hunan, jianghai) in 3L of distilled water to obtain an ammonium chloride solution, adding 100g of magnesium hydroxide powder (325 meshes in Western magnesium), preparing a suspension, adding the prepared suspension into a hydrothermal reaction kettle, stirring and heating to 80 ℃, keeping the temperature constant for 3 hours, then dropwise adding a 15% ammonia water solution into the hydrothermal reaction kettle by a high-pressure pump, stopping adding when the pH in the hydrothermal reaction kettle reaches 10, stirring at constant temperature for 3 hours, cooling, filtering, washing (distilled water), drying the obtained product at 105 ℃, crushing and grinding to obtain white powder. The particle size and morphology of the sample are observed by a transmission electron microscope (SEM), and FIG. 1 shows that the magnesium hydroxide (with the magnification of 20 ten thousand times) prepared by the embodiment is hexagonal platelet-shaped powder, the purity is higher than 99%, the appearance is regular, the dispersibility is good, the particle size of the crystal is mainly distributed between 500 nm and 800nm, the thickness of the crystal is mainly distributed between 20 nm and 60nm, and the specific surface area is 4m to 12m 2 The powder is not easy to agglomerate and is filtered quickly.
EXAMPLE III
Dissolving 200g of ammonium chloride (environmental protection and practical industry Co., ltd., hunan, jianghai) in 3L of distilled water to obtain an ammonium chloride solution, adding 100g of magnesium hydroxide powder (325 meshes in Western magnesium), preparing a suspension, adding the prepared suspension into a hydrothermal reaction kettle, stirring and heating to 100 ℃, keeping the temperature constant for 3 hours, then dropwise adding a 15% ammonia water solution into the hydrothermal reaction kettle by a high-pressure pump, stopping adding when the pH in the hydrothermal reaction kettle reaches 10, stirring at constant temperature for 3 hours, cooling, filtering, washing (distilled water), drying the obtained product at 105 ℃, crushing and grinding to obtain white powder. The particle size and morphology of the sample are observed by a transmission electron microscope (SEM), and FIG. 2 shows that the magnesium hydroxide (with the magnification of 20 ten thousand times) prepared by the embodiment has hexagonal platelet powder with purity higher than 99%, regular appearance and good dispersibility, the particle size of the crystal is mainly distributed between 200 nm and 400nm, and the crystal is in the shape of a regular crystalThe thickness of the coating is mainly distributed between 20 and 40nm, and the specific surface area is between 4 and 8m 2 The powder is not easy to agglomerate and is filtered quickly.
Example four
Dissolving 200g of ammonium chloride (Hunan Jianghai environmental protection industry Co., ltd.) in 3L of distilled water to obtain an ammonium chloride solution, adding 100g of magnesium hydroxide powder (Western magnesium industry 325 meshes) to prepare a suspension, adding the prepared suspension into a hydrothermal reaction kettle, stirring and heating to 120 ℃, keeping the temperature constant for 3 hours, then dropwise adding 15% ammonia water solution into the hydrothermal reaction kettle through a high-pressure pump, stopping adding when the pH value in the hydrothermal reaction kettle reaches 10, stirring at constant temperature for 3 hours, cooling, filtering, washing (distilled water), drying the obtained product at 105 ℃, crushing and grinding to obtain white powder. Observing the particle size and morphology of a sample by using a transmission electron microscope (SEM), wherein FIG. 3 shows magnesium hydroxide (with the magnification of 20 ten thousand times) prepared by the embodiment, FIG. 9 shows a diffraction diagram of magnesium hydroxide X-ray powder prepared by the embodiment, the powder is hexagonal plate crystals, the purity is higher than 99%, the appearance is regular, the dispersibility is good, the particle size of the crystals is mainly distributed in the range of 200-400nm, the thickness of the crystals is mainly distributed in the range of 20-40nm, and the specific surface area is 4-8m 2 The powder is not easy to agglomerate and is filtered quickly.
EXAMPLE five
Dissolving 200g of ammonium chloride (environmental protection and practical industry Co., ltd., hunan, jianghai) in 3L of distilled water to obtain an ammonium chloride solution, adding 100g of magnesium hydroxide powder (325 meshes in Western magnesium), preparing a suspension, adding the prepared suspension into a hydrothermal reaction kettle, stirring and heating to 150 ℃, keeping the temperature constant for 3 hours, then dropwise adding 15% ammonia water solution into the hydrothermal reaction kettle through a high-pressure pump, stopping adding when the pH in the hydrothermal reaction kettle reaches 10, stirring at constant temperature for 3 hours, cooling, filtering, washing (distilled water), drying the obtained product at 105 ℃, crushing and grinding to obtain white powder. The particle size and morphology of the sample are observed by a transmission electron microscope (SEM), and FIG. 4 shows that the magnesium hydroxide (with the magnification of 20 ten thousand times) prepared by the embodiment has hexagonal platelet powder, purity higher than 99%, regular appearance and good dispersibility, the particle size of the crystal is mainly distributed between 200 nm and 400nm, the thickness of the crystal is mainly distributed between 20 nm and 40nm, and the specific gravity of the crystal is 20 nm to 40nmThe surface area is 4-8m 2 The powder is not easy to agglomerate and is filtered quickly.
EXAMPLE six
Dissolving 200g of ammonium chloride (environmental protection and practical industry Co., ltd., hunan, jianghai) in 3L of distilled water to obtain an ammonium chloride solution, adding 100g of magnesium hydroxide powder (325 meshes in Western magnesium), preparing a suspension, adding the prepared suspension into a hydrothermal reaction kettle, stirring and heating to 120 ℃, keeping the temperature constant for 3 hours, then dropwise adding 10% of ammonia water solution into the hydrothermal reaction kettle by a high-pressure pump, stopping adding when the pH in the hydrothermal reaction kettle reaches 10, stirring at constant temperature for 3 hours, cooling, filtering, washing (distilled water), drying the obtained product at 105 ℃, crushing and grinding to obtain white powder. The particle size and morphology of the sample are observed by a transmission electron microscope (SEM), and FIG. 5 shows that the magnesium hydroxide (with the magnification of 20 ten thousand times) prepared by the embodiment has hexagonal platelet powder, purity higher than 99%, regular appearance and good dispersibility, the particle size of the crystal is mainly distributed between 400nm and 800nm, the thickness of the crystal is mainly distributed between 20 nm and 50nm, and the specific surface area is 5m to 20m 2 The powder is not easy to agglomerate and is filtered quickly.
EXAMPLE seven
Dissolving 200g of ammonium chloride (environmental protection and practical industry Co., ltd., hunan, jianghai) in 3L of distilled water to obtain an ammonium chloride solution, adding 100g of magnesium hydroxide powder (325 meshes in Western magnesium), preparing a suspension, adding the prepared suspension into a hydrothermal reaction kettle, stirring and heating to 120 ℃, keeping the temperature constant for 3 hours, then dropwise adding a 20% ammonia water solution into the hydrothermal reaction kettle by a high-pressure pump, stopping adding when the pH in the hydrothermal reaction kettle reaches 10, stirring at constant temperature for 3 hours, cooling, filtering, washing (distilled water), drying the obtained product at 105 ℃, crushing and grinding to obtain white powder. The particle size and morphology of the sample are observed by a transmission electron microscope (SEM), and FIG. 6 shows that the magnesium hydroxide (with the magnification of 20 ten thousand times) prepared by the embodiment has hexagonal powder, purity higher than 99%, regular appearance and good dispersibility, the particle size of the crystal is mainly distributed between 100 nm and 300nm, the thickness of the crystal is mainly distributed between 20 nm and 60nm, and the specific surface area is 4m to 15m 2 The powder is not easy to agglomerate and is filtered quickly.
Example eight
Dissolving 200g of ammonium chloride (environmental protection and practical industry Co., ltd., hunan, jianghai) in 3L of distilled water to obtain an ammonium chloride solution, adding 100g of magnesium hydroxide powder (325 meshes in Western magnesium), preparing a suspension, adding the prepared suspension into a hydrothermal reaction kettle, stirring and heating to 120 ℃, keeping the temperature constant for 3 hours, dropwise adding a 15% ammonia water solution into the hydrothermal reaction kettle by a high-pressure pump, stopping adding when the pH in the hydrothermal reaction kettle reaches 10, stirring at constant temperature for 2 hours, cooling, filtering, washing (distilled water), drying the obtained product at 105 ℃, crushing and grinding to obtain white powder. The particle size and morphology of the sample are observed by a transmission electron microscope (SEM), and FIG. 7 shows that the magnesium hydroxide (with the magnification of 20 ten thousand times) prepared by the embodiment has hexagonal platelet powder, purity higher than 99%, regular appearance and good dispersibility, the particle size of the crystal is mainly distributed between 400nm and 800nm, the thickness of the crystal is mainly distributed between 20 nm and 50nm, and the specific surface area is 4m to 20m 2 The powder is not easy to agglomerate and is filtered quickly.
Example nine
Dissolving 200g of ammonium chloride (environmental protection and practical industry Co., ltd., hunan, jianghai) in 3L of distilled water to obtain an ammonium chloride solution, adding 100g of magnesium hydroxide powder (325 meshes in Western magnesium), preparing a suspension, adding the prepared suspension into a hydrothermal reaction kettle, stirring and heating to 120 ℃, keeping the temperature constant for 3 hours, then dropwise adding a 15% ammonia water solution into the hydrothermal reaction kettle by a high-pressure pump, stopping adding when the pH in the hydrothermal reaction kettle reaches 10, stirring at constant temperature for 4 hours, cooling, filtering, washing (distilled water), drying the obtained product at 105 ℃, crushing and grinding to obtain white powder. The particle size and morphology of the sample are observed by a transmission electron microscope (SEM), and FIG. 8 shows that the magnesium hydroxide (with the magnification of 20 ten thousand times) prepared by the embodiment has hexagonal platelet powder, purity higher than 99%, regular appearance and good dispersibility, the particle size of the crystal is mainly distributed between 200 nm and 300nm, the thickness of the crystal is mainly distributed between 20 nm and 50nm, and the specific surface area is 4m to 15m 2 The powder is not easy to agglomerate and is filtered quickly.
Claims (4)
1. A method for preparing hexagonal magnesium hydroxide flame retardant by a one-step hydrothermal method, comprising the following steps:
(1) Mixing irregular magnesium hydroxide, ammonium chloride and water to obtain a mixed solution, adding the mixed solution into a closed hydrothermal reaction kettle, and stirring at the constant temperature of 40-120 ℃ for 0.5-2 hours to obtain a magnesium ion dissolved solution, wherein the dosage ratio of the irregular magnesium hydroxide, the ammonium chloride and the water is as follows: 50g-150g:250g-350g:2L-3L;
(2) And (2) dropwise adding the solution obtained in the step (1) into an ammonia water solution with the mass concentration of 10% -20% until the pH of the reaction solution is 8-10, stopping dropwise adding, stirring at a constant temperature for 2-3 hours to obtain a suspension, standing for 1 hour, and filtering and washing a precipitate to obtain the hexagonal magnesium hydroxide flame retardant.
2. The method of claim 1 wherein the irregular magnesium hydroxide is 325 mesh prismatic magnesium hydroxide.
3. The method of claim 1, wherein the ammonium chloride is 99.8% pure.
4. The method of claim 1, wherein the filtering, washing, drying and crushing step comprises: standing, filtering by using a filter pressing device, washing by using distilled water, drying at 105 ℃, and crushing to obtain the hexagonal magnesium hydroxide flame retardant.
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| CN115771908A (en) * | 2022-11-23 | 2023-03-10 | 北京化工大学 | Preparation method of low-chlorine magnesium hydroxide |
| CN116835616A (en) * | 2023-08-30 | 2023-10-03 | 山东艾科高分子材料有限公司 | Method for preparing high-dispersion hexagonal flaky magnesium hydroxide by high-activity light-burned magnesium oxide through one-step hydrothermal method |
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| CN107758706A (en) * | 2017-09-25 | 2018-03-06 | 沈阳化工大学 | One-step method prepares cubic pieces flame retardant of magnesium hydroxide process |
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| CN107758706A (en) * | 2017-09-25 | 2018-03-06 | 沈阳化工大学 | One-step method prepares cubic pieces flame retardant of magnesium hydroxide process |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115771908A (en) * | 2022-11-23 | 2023-03-10 | 北京化工大学 | Preparation method of low-chlorine magnesium hydroxide |
| CN116835616A (en) * | 2023-08-30 | 2023-10-03 | 山东艾科高分子材料有限公司 | Method for preparing high-dispersion hexagonal flaky magnesium hydroxide by high-activity light-burned magnesium oxide through one-step hydrothermal method |
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