CN114477248A - Method for preparing magnesium hydroxide flame retardant by using magnesium oxide two-step method - Google Patents
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- CN114477248A CN114477248A CN202210175198.1A CN202210175198A CN114477248A CN 114477248 A CN114477248 A CN 114477248A CN 202210175198 A CN202210175198 A CN 202210175198A CN 114477248 A CN114477248 A CN 114477248A
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- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 title claims abstract description 53
- 239000000347 magnesium hydroxide Substances 0.000 title claims abstract description 46
- 229910001862 magnesium hydroxide Inorganic materials 0.000 title claims abstract description 46
- 238000000034 method Methods 0.000 title claims abstract description 28
- 239000000395 magnesium oxide Substances 0.000 title claims abstract description 23
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 title claims abstract description 23
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 title claims abstract description 23
- 239000003063 flame retardant Substances 0.000 title claims abstract description 21
- 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 20
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 45
- 238000001914 filtration Methods 0.000 claims abstract description 30
- 238000003756 stirring Methods 0.000 claims abstract description 24
- 238000005406 washing Methods 0.000 claims abstract description 19
- 238000001035 drying Methods 0.000 claims abstract description 18
- 230000036571 hydration Effects 0.000 claims abstract description 13
- 238000006703 hydration reaction Methods 0.000 claims abstract description 13
- 238000001132 ultrasonic dispersion Methods 0.000 claims abstract description 10
- 239000002270 dispersing agent Substances 0.000 claims abstract description 8
- 230000008569 process Effects 0.000 claims abstract description 8
- 239000000047 product Substances 0.000 claims abstract description 8
- 238000006243 chemical reaction Methods 0.000 claims abstract description 6
- 238000000605 extraction Methods 0.000 claims abstract description 3
- 239000002244 precipitate Substances 0.000 claims abstract description 3
- 230000000887 hydrating effect Effects 0.000 claims abstract 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- BCKXLBQYZLBQEK-KVVVOXFISA-M Sodium oleate Chemical group [Na+].CCCCCCCC\C=C/CCCCCCCC([O-])=O BCKXLBQYZLBQEK-KVVVOXFISA-M 0.000 claims description 9
- 230000000694 effects Effects 0.000 claims description 8
- 239000000725 suspension Substances 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 3
- 239000012153 distilled water Substances 0.000 claims description 2
- 238000000926 separation method Methods 0.000 claims 1
- 239000000843 powder Substances 0.000 description 28
- 239000002245 particle Substances 0.000 description 20
- 239000013078 crystal Substances 0.000 description 19
- 238000001816 cooling Methods 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 8
- 239000006185 dispersion Substances 0.000 description 7
- 238000000227 grinding Methods 0.000 description 7
- 238000001027 hydrothermal synthesis Methods 0.000 description 7
- 239000008213 purified water Substances 0.000 description 7
- 229920001971 elastomer Polymers 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000005060 rubber Substances 0.000 description 4
- 238000005054 agglomeration Methods 0.000 description 3
- 230000002776 aggregation Effects 0.000 description 3
- -1 chemical engineering Substances 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
- 239000004800 polyvinyl chloride Substances 0.000 description 3
- 229920000915 polyvinyl chloride Polymers 0.000 description 3
- 239000004698 Polyethylene Substances 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 238000003889 chemical engineering Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 238000005065 mining Methods 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 239000002861 polymer material Substances 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- 229920002943 EPDM rubber Polymers 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000009471 action Effects 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
- 238000007796 conventional method Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000007613 environmental effect Effects 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
- 230000020169 heat generation Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical class [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 229910001948 sodium oxide Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- 229920006305 unsaturated polyester Polymers 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
- C01F5/16—Magnesium hydroxide by treating magnesia, e.g. calcined dolomite, with water or solutions of salts not containing magnesium
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/20—Oxides; Hydroxides
- C08K3/22—Oxides; Hydroxides of metals
-
- 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
-
- 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
- C01P2004/61—Micrometer sized, i.e. from 1-100 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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/20—Oxides; Hydroxides
- C08K3/22—Oxides; Hydroxides of metals
- C08K2003/2217—Oxides; Hydroxides of metals of magnesium
- C08K2003/2224—Magnesium hydroxide
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Health & Medical Sciences (AREA)
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- Polymers & Plastics (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention provides a method for preparing a magnesium hydroxide flame retardant by a magnesium oxide two-step method, which comprises the steps of firstly hydrating magnesium oxide to prepare sheet magnesium hydroxide, adding a dispersing agent in the hydration process to perform ultrasonic dispersion, keeping the temperature at 70-90 ℃, keeping the hydration time at 3h, standing for 1h, then performing layered extraction on a hydration product, adding the extracted hydration product into a closed reaction kettle, adding 240g-720g of sodium hydroxide, stirring at the constant temperature of 120-200 ℃ for 2-4h to obtain a modified magnesium hydroxide solution, standing for 1h, filtering, washing, drying and crushing a precipitate to obtain the magnesium hydroxide flame retardant with a regular structure.
Description
Technical Field
The invention relates to a method for preparing a magnesium hydroxide flame retardant by a magnesium oxide two-step method.
Background
With the wide application of high molecular polymer materials in the fields of building, 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 these problems directly promote the development of the flame retardant market and promote the research, development and production of magnesium hydroxide.
Magnesium hydroxide is widely used in various resins, such as PE, PP and the like, as a flame retardant filler, and in the industrial fields of chemical industry, 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 molecular 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 the crystal grains of the magnesium hydroxide is divided into two aspects of crystal nucleation and growth, the growth and nucleation of the commonly synthesized magnesium hydroxide crystal are inconsistent, and the appearance is irregular, so that the magnesium hydroxide has higher surface energy, poor dispersion and easy agglomeration. The dispersibility and particle size distribution of the magnesium hydroxide are improved by external mechanical action such as supergravity, ultrasonic method/microwave method and the like, but the improvement of the surface energy of the particle size is limited, and a further surface modification process is needed to obtain 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, environment-friendly in process, high in product purity and regular in appearance.
The technical scheme of the invention is as follows: a method for preparing a magnesium hydroxide flame retardant by a magnesium oxide two-step method comprises the following steps:
(1) the high-purity and high-activity magnesium oxide is hydrated to prepare flaky magnesium hydroxide, a dispersing agent is added in the hydration process for ultrasonic dispersion, the hydration temperature is 70-90 ℃, and the hydration time is 2-4 h.
(2) Standing the hydration product obtained in the step (1) for 1h, then performing layered extraction, adding the extracted hydration product into a closed reaction kettle, adding sodium hydroxide, and stirring at constant temperature for 2-4h to obtain a modified magnesium hydroxide suspension.
(3) The proportion of the high-purity and high-activity magnesium oxide, water and the dispersing agent is 100 g: 3L: 0.5g, ratio of hydrated magnesium hydroxide suspension to sodium hydroxide solids of 3.2 kg: (240 g-720 g).
(4) And (3) standing the suspension obtained in the step (2) for 1h, and filtering and washing precipitates to obtain the regular magnesium hydroxide flame retardant.
The first step of the invention is carried out in a container with heating and ultrasonic, and the second step is carried out in a closed reaction kettle with constant temperature and pressure, and the temperature is controlled during operation.
The magnesium oxide is conventional high-purity and high-activity magnesium oxide, the mesh number is 325 meshes, and the content of the magnesium oxide is more than 99 percent.
The sodium hydroxide and oxide is flaky solid with the content of more than 99 percent.
The dispersant is sodium oleate with the content of more than 99 percent.
The temperature of the reaction kettle in the step (2) is 120-200 ℃.
The filtration washing is a conventional method, and the filtration washing steps of the invention are as follows: and after the hydrothermal modification is finished, cooling, filtering to obtain filter pressing, washing to obtain distilled water, preferably selecting flash evaporation equipment, and crushing to obtain a millstone type crusher to obtain the magnesium hydroxide flame retardant, wherein the drying temperature is 105 ℃.
According to the invention, the high-purity and high-dispersion magnesium hydroxide is prepared, the particle size of the product is tested to be 1.5-2.5um, the specific surface area is tested to be 5-15 m/g, the purity is greater than 99.2%, and the crystal is in a hexagonal plate structure.
The invention is best embodied in that: (1) the magnesium oxide hydrated magnesium hydroxide has low cost, and the filtration is quick after hydrothermal modification, thereby reducing the energy consumption; (2) the modified magnesium hydroxide has regular appearance structure, uniform particle size, small specific surface area and good dispersion; (3) the production process is in a closed reaction kettle, and after the production process is finished, the filtered and washed water can be continuously used without leakage and sewage discharge, so that no environmental pollution is ensured, and the cost and the environmental pollution are reduced.
Drawings
FIG. 1 example one (150 ℃ C.) hydrothermally modifies the appearance of magnesium hydroxide particles.
FIG. 2 example two (180 ℃ C.) hydrothermally modifies the appearance of magnesium hydroxide particles.
FIG. 3 example III (200 ℃ C.) hydrothermally modifies the appearance of magnesium hydroxide particles.
FIG. 4 example four (2 mol/L NaOH solution) hydrothermally modifies the appearance of magnesium hydroxide particles.
FIG. 5 example five (6 mol/L NaOH solution) hydrothermally modifies the appearance of magnesium hydroxide particles.
Figure 6 example six (2 h) hydrothermally modifies the appearance of the magnesium hydroxide particles.
Figure 7 example seven (6 h) hydrothermally modified magnesium hydroxide particle appearance.
FIG. 8 XRD pattern of hydrothermally modified magnesium hydroxide of example III (200 ℃ C.).
Detailed Description
The following further describes the present invention with reference to specific embodiments, but the scope of the invention is not limited to the following.
Example one
100g of magnesium oxide powder (325 mesh) was wetted with 3L of water, and 0.5g of sodium oleate was added. Adding into ultrasonic dispersion equipment, preheating at 90 deg.C for 3 hr, standing for 1 hr, separating, adding into hydrothermal reaction kettle, stirring 480g sodium hydroxide for dissolving, stirring and heating to 150 deg.C, stirring at constant temperature for 4 hr, standing for 1 hr, cooling, separating, filtering, washing (filtering purified water), drying at 105 deg.C, crushing, and grinding to obtain white powder. FIG. 1 shows the magnesium hydroxide (40 ten thousand times magnification) prepared by the present embodiment, the powder structure is a more regular sheet structure, the crystal particle size is mainly distributed at 400-600nm, the crystal thickness is mainly distributed at 50-70nm, and the specific surface area is 6-10m2The powder has a purity higher than 99%, good dispersibility and is not easy to agglomerate.
Example two
100g of magnesium oxide powder (siemens 325 mesh) was wetted with 3L of water, and 0.5g of sodium oleate was added. Adding into ultrasonic dispersion equipment, preheating at 90 deg.C for 3 hr, standing for 1 hr, separating, adding into hydrothermal reaction kettle, stirring 480g sodium hydroxide for dissolving, stirring and heating to 180 deg.C, stirring at constant temperature for 4 hr, standing for 1 hr, cooling, separating, filtering, washing (filtering purified water), drying at 105 deg.C, crushing, and grinding to obtain white powder. FIG. 2 shows the magnesium hydroxide (40 ten thousand times magnification) prepared by this embodiment, the powder structure is similar to hexagonal plate structure, the crystal particle size is mainly distributed at 400-600nm, the crystal thickness is mainly distributed at 40-60nm, and the specific surface area is 6-10m2The purity of the powder is higher than 99 percent, the dispersibility is good, the agglomeration is not easy to occur, and the filtering time is short.
EXAMPLE III
100g of magnesium oxide powder (325 mesh) was wetted with 3L of water, and 0.5g of sodium oleate was added. Adding into ultrasonic dispersion equipment, preheating at 90 deg.C for 3 hr, standing for 1 hr, separating, adding into hydrothermal reaction kettle, stirring and dissolving 480g sodium hydroxide, stirring and heating to 200 deg.C, stirring at constant temperature for 4 hr, standing for 1 hr, cooling, separating, filtering, washing (filtering purified water), drying at 105 deg.C, crushing, and grinding to obtain white powder. FIG. 3 shows the magnesium hydroxide prepared by the present embodiment (with a magnification of 40 ten thousand times), FIG. 8 shows the X-ray powder diffraction pattern of the magnesium hydroxide prepared by the present embodiment, the powder structure is a hexagonal plate structure, the crystal particle size is mainly distributed at 300-600nm, the crystal thickness is mainly distributed at 50-80nm, the specific surface area is small, and the thickness is 4-10m2The powder does not agglomerate, and the filtering, washing and drying are quick.
Example four
100g of magnesium oxide powder (325 mesh) was wetted with 3L of water, and 0.5g of sodium oleate was added. Adding into ultrasonic dispersion equipment, preheating at 90 deg.C for 3 hr, standing for 1 hr, separating, adding into hydrothermal reaction kettle, stirring and dissolving 240g sodium hydroxide, stirring and heating to 200 deg.C, stirring at constant temperature for 4 hr, standing for 1 hr, cooling, separating, filtering, washing (filtering purified water), drying at 105 deg.CDrying, crushing and grinding to obtain white powder. FIG. 4 shows the magnesium hydroxide (40 ten thousand times magnification) prepared by this embodiment, the powder structure is a lamellar structure with poor regularity, the crystal particle size is mainly distributed at 500-800nm, the crystal thickness is mainly distributed at 20-60nm, the specific surface area is small, and the specific surface area is 6-12m2The powder can be agglomerated, and the filtration, washing and drying are easier.
EXAMPLE five
100g of magnesium oxide powder (325 mesh) was wetted with 3L of water, and 0.5g of sodium oleate was added. Adding into ultrasonic dispersion equipment, preheating at 90 deg.C for 3 hr, standing for 1 hr, separating, adding into hydrothermal reaction kettle, stirring for dissolving 720g sodium hydroxide, stirring and heating to 200 deg.C, stirring at constant temperature for 4 hr, standing for 1 hr, cooling, separating, filtering, washing (filtering purified water), drying at 105 deg.C, crushing, and grinding to obtain white powder. FIG. 5 shows the magnesium hydroxide (40 ten thousand times magnification) prepared by the present embodiment, the powder structure is a more regular sheet structure, the crystal particle size is mainly distributed at 400-800nm, the crystal thickness is mainly distributed at 50-70nm, the specific surface area is small, and the thickness is 5-10m2(mg), the powder dispersion is not good enough and the filtration is slow.
EXAMPLE six
100g of magnesium oxide powder (325 mesh) was wetted with 3L of water, and 0.5g of sodium oleate was added. Adding into ultrasonic dispersion equipment, preheating at 90 deg.C for 3 hr, standing for 1 hr, separating, adding into hydrothermal reaction kettle, stirring and dissolving 480g sodium hydroxide, stirring and heating to 200 deg.C, stirring at constant temperature for 2 hr, standing for 1 hr, cooling, separating, filtering, washing (filtering purified water), drying at 105 deg.C, crushing, and grinding to obtain white powder. FIG. 6 shows the magnesium hydroxide (40 ten thousand times magnification) prepared by the present embodiment, the powder structure is a more regular sheet structure, the crystal particle size is mainly distributed at 400-700nm, the crystal thickness is mainly distributed at 40-80nm, and the specific surface area is 4-12m2And/g, the powder is not easy to agglomerate in the processes of filtering, washing and drying.
EXAMPLE seven
100g of magnesium oxide powder (325 mesh) was wetted with 3L of water, and 0.5g of sodium oleate was added. Together areAdding into ultrasonic dispersion equipment, preheating at 90 deg.C for 3 hr, standing for 1 hr, separating, adding into hydrothermal reaction kettle, stirring and dissolving 480g sodium hydroxide, stirring and heating to 200 deg.C, stirring at constant temperature for 6 hr, standing for 1 hr, cooling, separating, filtering, washing (filtering purified water), drying at 105 deg.C, crushing, and grinding to obtain white powder. FIG. 7 shows the magnesium hydroxide (40 ten thousand times magnification) prepared by the present embodiment, the powder structure is similar to hexagonal plate structure, the crystal particle size is mainly distributed at 200-600nm, the crystal thickness is mainly distributed at 50-80nm, and the specific surface area is 4-10m2And/g, the powder is fast in the processes of filtering, washing and drying, and is not easy to agglomerate.
Claims (6)
1. A method for preparing a magnesium hydroxide flame retardant by a two-step magnesium oxide process, the method comprising:
(1) hydrating high-purity and high-activity magnesium oxide to prepare flaky magnesium hydroxide, adding a dispersant in the hydration process to perform ultrasonic dispersion, controlling the hydration temperature to be 70-90 ℃, controlling the hydration time to be 2-4h, performing layered extraction after standing for 1h, adding the extracted hydration product into a closed reaction kettle, adding sodium hydroxide, stirring at the constant temperature of 120-200 ℃ for 2-4h to obtain a modified magnesium hydroxide suspension, wherein the ratio of magnesium oxide (high purity and high activity), water and the dispersant is 100 g: 3L: 0.5g, ratio of hydrated magnesium hydroxide suspension to sodium hydroxide solids of 3.2 kg: 240g-720 g; (2) and (2) standing the modified magnesium hydroxide obtained in the step (1) for 1h, filtering, washing, drying and crushing the precipitate to obtain the regular magnesium hydroxide flame retardant.
2. The method of claim 1, wherein the high purity and high activity magnesium oxide has a 325 mesh size and a purity greater than 99%.
3. The method of claim 1 wherein the dispersant is sodium oleate, the purity being greater than 99%.
4. The method of claim 1, wherein the dispersing is ultrasonic dispersing during which a dispersing agent is added.
5. The method according to claim 1, wherein the filtration washing process comprises standing the suspension for separation, filtering the suspension with a filter press device, and washing the suspension with distilled water.
6. The method of claim 1, wherein the drying, crushing to 105 ℃ drying, crushing to a millstone crusher, results in the magnesium hydroxide flame retardant having a hexagonal structure.
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CN113548682A (en) * | 2021-07-22 | 2021-10-26 | 安徽大学绿色产业创新研究院 | Method for preparing hexagonal flaky flame-retardant magnesium hydroxide from natural hydromagnesite |
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张玉星 等: "氧化镁两步法制备阻燃型氢氧化镁", 《无机化学学报》 * |
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