Magnesium hydroxide is a kind of green, low-cost and environment-friendly inorganic additive flame retardant. It has the advantages of good thermal stability and non-toxicity. It can be widely added to polymer materials such as plastics, rubber and coatings to improve their flame retardant properties. However, the hexagonal flake-like nanometer magnesium hydroxide material with small particle size and low surface polarity has good dispersibility and nanometer activity. In the case of almost no impact on the use of strength, can significantly improve the material flame retardant, smoke, drip, filling and other properties. However, the synthesis process of regular and uniform nanometer hexagonal flake magnesium hydroxide is relatively complex. At present, the large-scale preparation of hexagonal flake nanometer magnesium hydroxide with good morphology is the difficulty of the industry.
The invention magnesium raw materials, through two-step, magnesium raw material synthesis of nano magnesium oxide powder first, then by nanometer technology to high concentrations of nano magnesium oxide powder dispersed in aqueous medium, form the high concentration of slurry, and then by the appropriate roasting drying process nanometer magnesia slurry preparation into nano hexagonal flake magnesium hydroxide. The nanometer hexagonal sheet magnesium hydroxide synthesized by this method can be prepared in large quantities and at low cost, and the synthesized sheets are uniformly dispersed with little overall difference, and the properties of the powder are significantly improved.
The purpose of the present invention is to breakthrough the traditional methods of the preparation of magnesium hydroxide piece of uneven thickness, size is not consistent the difficulty, the synthesis methods and technology innovation, namely the first particle size controllable preparation of nano magnesium oxide powder, reuse nanometer lapping technology and special drying process for the preparation of nanometer magnesium hydroxide paste and powder.
In order to achieve the above desired purpose, the invention adopts the following technical scheme:
The preparation method of a hexagonal flake nano-sized magnesium hydroxide material provided by the invention firstly prepares nano-sized magnesium hydroxide powder with controllable particle size, and then prepares nano-sized magnesium hydroxide slurry and powder by nano-grinding technology and special drying process. The process comprises the following steps:
A. Premix water, magnesium-containing raw materials and sodium carbonate in proportion to form a mixture, and react with a high-pressure reactor in an oven at 150 ~ 200℃ for 8 ~ 48 hours to prepare nano-sized magnesium hydroxide precursor solution;
B. The precursor solution of nano-sized magnesium hydroxide prepared in step A was washed, centrifuged, and then ground by high-energy ball mill to prepare nano-sized magnesium hydroxide pulp;
C. The nano-sized magnesium hydroxide pulp prepared in step b was calcined at a low temperature of 350 ~ 500℃ to obtain nano-sized magnesium oxide powder;
D. The nano-sized magnesium oxide powder prepared in step c was pre-dispersed by high-frequency ultrasonic wave, and the solid content of nano-sized magnesium oxide was 5%-65% until the particle size of solid particles in the mixed solution reached 300nm;
E. Add the dispersant to the mixed solution of magnesium oxide prepared in step d, and continue to grind with the nano-grinder until the particle size of solid particles in the dispersion solution reaches below 100nm, so as to prepare high concentration of water-based nano-sized magnesium oxide slurry;
F. Place the water-based nano-sized magnesium hydroxide slurry prepared in step E in a drying oven and react at 100 ~ 200℃ for 4 ~ 48 hours to obtain uniformly dispersed hexagonal flake nano-sized magnesium hydroxide slurry, which is then sprayed and dried to obtain hexagonal flake nano-sized magnesium hydroxide powder material.
In some embodiments, the mass ratio of water, magnesium-containing raw materials, and sodium carbonate described in step A is 1:(0.1 ~ 1.2) :(0.01 ~ 0.1), and the magnesium-containing raw materials are one of magnesium chloride, magnesium sulfate, magnesium oxide, and magnesium hydroxide, or a combination thereof.
In some emboDIments, step E, the dispersant is one of BYK190, BYK106, BYK182, BYK184, DE QIAN 904S, MOK5032 or a combination thereof, where the mass ratio of the magnesium oxide mixed solution to the dispersant is 1 (0.05 ~ 0.3).
In some embodiments, step E, the size of the nano-grinder grinding medium zirconium bead is 0.4mm, 0.2mm, 0.1mm or 0.05mm.
Compared with the existing technology, the present invention provides a kind of hexagonal flake preparation methods of nanometer magnesium hydroxide material, its advantage is that: the preparation of the present invention is hexagonal flake nanometer magnesium hydroxide material to maintain the scale in the nanometer level and the morphology of homogeneity, relieve the phenomenon of particle reunion and morphology of different sizes and also greatly improve the dispersivity of the hexagonal flake material of magnesium hydroxide.
Specific implementation mode
The details of the realization of the invention are described below through specific examples, but the scope of protection of the invention is not limited to these embodiments.
Embodiment 1:
The nano-sized magnesium hydroxide precursor was prepared by premixing water, magnesium chloride and sodium carbonate with the ratio of 1:0.1:0.01, and reacting in a high-pressure reactor at 150℃ for 8 hours in an oven. The prepared nano-sized magnesium hydroxide precursor solution was washed, centrifuged, and then ground into nano-sized magnesium hydroxide slurry by high-energy ball mill. The prepared nano-sized magnesium hydroxide pulp was calcined at low temperature of 350℃ to obtain nano-sized magnesium oxide powder. The prepared nano-sized magnesium oxide powder was pre-dispersed by high-frequency ultrasonic wave. The size of the grinding medium zirconium bead was 0.4mm, and the solid content of nano-sized magnesium oxide was 5%, until the particle size of solid particles in the mixed solution reached 300nm, D90. The dispersant BYK190 was added into the mixed solution of magnesium oxide prepared in the above steps, and the grinding process was continued by the nano-grinding machine until the particle size of the solid particles in the dispersion solution reached below 100nm, so as to prepare high concentration of water-based nano-sized magnesium oxide slurry. The prepared water-based nano-sized magnesium hydroxide slurry was placed in a drying oven and reacted at 100℃ for 4 hours to obtain uniformly dispersed hexagonal flake nano-sized magnesium hydroxide slurry, which was then sprayed and dried to obtain hexagonal flake nano-sized magnesium hydroxide powder material.
Embodiment 2:
Nanometer magnesium hydroxide precursor was prepared by premixing water, magnesium chloride and sodium carbonate with a ratio of 1:0.6:0.06, and reacting in a high-pressure reactor at 180℃ for 8 hours in an oven. The prepared nano-sized magnesium hydroxide precursor solution was washed, centrifuged, and then ground into nano-sized magnesium hydroxide slurry by high-energy ball mill. The prepared nano-sized magnesium hydroxide pulp was calcined at a low temperature of 400℃ to obtain nano-sized magnesium oxide powder. The prepared nano-sized magnesium oxide powder was pre-dispersed by high-frequency ultrasonic wave. The size of the grinding medium zirconium bead was 0.2mm, and the solid content of nano-sized magnesium oxide was 30%, until the particle size of the solid particles in the mixed solution reached 300nm. The dispersant BYK182 was added into the mixed solution of magnesium oxide prepared in the above steps, and the grinding process was continued by the nano-grinding machine until the particle size of the solid particles in the dispersion solution reached below 100nm, so as to prepare high concentration of water-based nano-sized magnesium oxide slurry. The prepared water-based nano-sized magnesium hydroxide slurry was placed in a drying oven for reaction at 150℃ for 24 hours to obtain uniformly dispersed hexagonal flake nano-sized magnesium hydroxide slurry. The slurry was then sprayed and dried to obtain hexagonal flake nano-sized magnesium hydroxide powder material.
Embodiment 3:
The nano-sized magnesium hydroxide precursor was prepared by premixed water, magnesium chloride and sodium carbonate in the ratio of 1:1.0:0.08, and then reacted with a high-pressure reactor in the oven at 180℃ for 36 hours. The prepared nano-sized magnesium hydroxide precursor solution was washed, centrifuged, and then ground into nano-sized magnesium hydroxide slurry by high-energy ball mill. The prepared nano-sized magnesium hydroxide pulp was calcined at 450℃ to obtain nano-sized magnesium oxide powder. The prepared nano-sized magnesium oxide powder was pre-dispersed by high-frequency ultrasonic wave. The size of zirconium bead in the grinding medium was 0.1mm, and the solid content of nano-sized magnesium oxide was 45%, until the particle size of solid particles in the mixed solution reached 300nm. The dispersant DeQian 904S was added to the mixed solution of magnesium oxide prepared by the above steps, and the nano-grinding machine was used to continue grinding until the particle size of the solid particles in the dispersion solution reached below 100nm, so as to prepare a high concentration of water-based nano-sized magnesium oxide slurry; The prepared water-based nano-sized magnesium hydroxide slurry was placed in a drying oven for reaction at 180℃ for 36 hours to obtain uniformly dispersed hexagonal flake nano-sized magnesium hydroxide slurry, which was then sprayed and dried to obtain hexagonal flake nano-sized magnesium hydroxide powder material.
Embodiment 4:
Nanometer magnesium hydroxide precursor was prepared by premixing water, magnesium chloride and sodium carbonate with a ratio of 1:1.2:0.1, and reacting in a high-pressure reactor at 200℃ for 48 hours in an oven. The prepared nano-sized magnesium hydroxide precursor solution was washed, centrifuged, and then ground into nano-sized magnesium hydroxide slurry by high-energy ball mill. The prepared nano-sized magnesium hydroxide pulp was calcined at a low temperature of 500℃ to obtain nano-sized magnesium oxide powder. The prepared nano-sized magnesium oxide powder was pre-dispersed by high-frequency ultrasonic wave. The size of zirconium bead in the grinding medium was 0.05mm, and the solid content of nano-sized magnesium oxide was 65%, until the particle size of solid particles in the mixed solution reached 300nm. The dispersant MOK5032 was added to the mixed solution of magnesium oxide prepared in the above steps, and the grinding process was continued by the nano-grinding machine until the particle size of the solid particles in the dispersion solution reached below 100nm, so as to prepare high concentration of water-based nano-sized magnesium oxide slurry. The prepared water-based nano-sized magnesium hydroxide slurry was placed in a drying oven and reacted at 200℃ for 48 hours to obtain uniformly dispersed hexagonal flake nano-sized magnesium hydroxide slurry, which was then sprayed and dried to obtain hexagonal flake nano-sized magnesium hydroxide powder material.
Said the express and describes the optimization implementation example of the present invention, as mentioned above, should understand the form of the present invention is not limited to this disclosure, should not be regarded as to exclude other cases, and can be used for various other combinations, modification, and the environment, and be able to ideas within the scope of the invention of described in this article, through the teaching technology or related field or change of knowledge, and the field personnel to change and change is not from the spirit and scope of the invention, should be in the present invention enclosed within the protection of the right to ask.
