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CN-121974396-A - Preparation method of high-end flame-retardant sodium pyroantimonate with controllable particle size

CN121974396ACN 121974396 ACN121974396 ACN 121974396ACN-121974396-A

Abstract

The invention relates to the technical field of inorganic chemical synthesis and discloses a preparation method of high-end flame-retardant sodium pyroantimonate with controllable particle size, which comprises the steps of completely dissolving antimony trioxide in a sodium hydroxide solution, thermally filtering to construct a homogeneous metastable precursor without solid phase residue, presetting excessive oxidant and seed crystals in a base solution to establish an oxidant-rich receiving phase, strictly controlling reverse continuous flow addition of the precursor into the receiving phase, dynamically matching the injection rate of antimonite ions and the surface area of the seed crystals in real time under the condition of maintaining excessive strong oxidation potential energy of the peroxide in the whole process, carrying out reaction in a kinetic metastable zone for inhibiting secondary nucleation until the end of the feeding, and ageing and post-treating to obtain a product.

Inventors

  • LONG SHIGEN
  • LI WEIXING

Assignees

  • 株洲安特新材料科技有限公司

Dates

Publication Date
20260505
Application Date
20260320

Claims (9)

  1. 1. The preparation method of the sodium pyroantimonate with controllable particle size for high-end flame retardance is characterized by comprising the following steps of: Step S1, constructing a homogeneous metastable state precursor, adding antimony trioxide powder into a sodium hydroxide aqueous solution, completely dissociating solid phase particles under the conditions of heating and stirring and generating a coordination reaction until the system is converted into a transparent and clear sodium antimonite precursor solution, and immediately performing precise hot filtration operation on the sodium antimonite precursor solution to intercept insoluble mechanical impurities, thereby obtaining a homogeneous fluid filling without solid phase residues; Step S2, establishing a seed crystal induction field, preparing a base solution containing a preset number of primary seed crystals and having hydrogen peroxide concentration in a stoichiometric excess state in a reactor, and keeping the temperature of the base solution constant in a preset crystallization temperature interval to form an oxidant-rich receiving phase; Step S3, performing reverse lean solute dynamic locking, taking the homogeneous phase flowing liquid prepared in the step S1 as a disperse phase under the conditions of maintaining stirring and constant temperature, and injecting the homogeneous phase flowing liquid into the oxygen-enriched agent carrying phase in the step S2 in a continuous flow adding mode, wherein in the flowing adding process, a metastable zone edge pushing strategy is strictly performed, the molar excess state of hydrogen peroxide in the base liquid relative to antimonite ions is always maintained to construct a strong oxidation potential energy well, the adding rate of the homogeneous phase flowing liquid is controlled in real time, so that the instant supersaturation degree of sodium pyroantimonate generated by instant oxidation of antimonite ions entering the base liquid in a liquid phase is always maintained in a metastable zone which is lower than the burst nucleation critical value of a system and higher than the equilibrium solubility, and new solute molecules are directionally grown on the surface of the existing seed crystal until the flowing adding is finished; And S4, post-treatment, namely aging, solid-liquid separation, washing and drying the reacted slurry to obtain a sodium pyroantimonate product.
  2. 2. The preparation method of the sodium pyroantimonate with the controllable particle size for high-end flame retardance, which is disclosed in claim 1, is characterized in that a metastable zone edge propulsion strategy executed in the step S3 specifically comprises the steps of establishing a nonlinear coupling mechanism of an oxidation reaction rate and a lattice stacking rate, wherein the mechanism requires that the hydrogen peroxide stock in a base solution is always kept between 1.1 times and 1.5 times of a theoretical reaction stoichiometric ratio in the whole running-in process, so that antimonite ions entering reaction microelements are ensured to complete valence state transition before each antimonite ion diffuses into a bulk solution, and meanwhile, controlling the running-in rate of a homogeneous flow liquid feeding to follow a dynamic increasing curve which is positively correlated with the crystal growth surface area, so as to maintain the solute feeding flux on the unit crystal surface area within a dynamic stability window for inhibiting secondary nucleation.
  3. 3. The method for preparing high-end flame-retardant sodium pyroantimonate with controllable particle size according to claim 1, wherein in the step S1, the process of dissolving antimony trioxide powder in a sodium hydroxide aqueous solution is carried out at a temperature of 90-105 ℃, the initial concentration of sodium hydroxide is controlled to ensure that the mass concentration of antimony element in the prepared sodium antimonate precursor solution is 100-180 g/l, and an alkali-resistant filter medium with a pore diameter of 0.45-1.0 microns is adopted for precise thermal filtration operation, wherein the solution temperature is maintained to be not lower than 80 ℃ during filtration.
  4. 4. The method for preparing the sodium pyroantimonate with controllable particle size for high-end flame retardance according to claim 1, wherein in the step S2, the specific operation of establishing a seed crystal induction field is that in a base solution containing hydrogen peroxide, homogeneous-phase liquid filling accounting for 3-5% of the total feeding amount is rapidly injected at the temperature of 40-50 ℃, a high-supersaturation induction system is utilized to implode for generating primary crystal nuclei in 60-120 seconds, and then the feeding is stopped and the temperature is raised to 60-75 ℃ to serve as the crystallization temperature in the step S3.
  5. 5. The preparation method of the sodium pyroantimonate with the controllable particle size for high-end flame retardance according to claim 1, wherein in the step S3, sodium hydroxide solution is synchronously added dropwise into a reaction system through an independent feeding pipeline while reverse poor solute dynamics locking is carried out, and the pH value of the reaction system is wholly constant between 12.5 and 13.5 by utilizing an online pH detection feedback mechanism so as to maintain the coordination structure stability of pyroantimonate ions in a liquid phase and prevent generation of metaantimonate colloid impurity phases caused by local acid fluctuation.
  6. 6. The method for preparing high-end flame-retardant sodium pyroantimonate with controllable particle size according to claim 1, wherein the purity of the antimonous oxide powder used in the step S1 is not lower than 99.5%, the homogeneous flow liquid is kept in a storage container and is in a continuous heat-insulating stirring state before the flow liquid enters the feeding operation of the step S3, and the hydrogen peroxide in the base liquid is derived from an industrial grade hydrogen peroxide solution with the concentration of 27.5-35%, and deionized water is added for dilution when the base liquid is prepared.
  7. 7. The preparation method of the sodium pyroantimonate with the controllable particle size for high-end flame retardance according to claim 1, wherein the total feeding duration of the step S3 is controlled to be between 120 minutes and 240 minutes, and the stirring linear speed in a reaction system is controlled to be between 2.0 meters per second and 4.0 meters per second in the feeding process so as to ensure that injected homogeneous flowing liquid is instantaneously diluted by base liquid on a microscopic mixing scale, and avoid the formation of a local high concentration region.
  8. 8. The method for preparing sodium pyroantimonate for high-end flame retardance with controllable particle size according to claim 1, wherein the ageing operation in the step S4 comprises the steps of heating the reaction slurry to 85-95 ℃ and maintaining a low-speed stirring state for 2-4 hours, enabling the surface of the crystal to generate an Oswald ripening effect to repair crystal face defects, and carrying out multiple displacement washing on a filter cake by deionized water until the conductivity of the filtrate is reduced to below 100 microsiemens per centimeter.
  9. 9. The method for preparing sodium pyroantimonate for high-end flame retardance according to claim 1, wherein the crystal morphology of the sodium pyroantimonate product prepared by the method is in a regular cube or octahedral structure, the particle size distribution coefficient is smaller than 1.2, the content of residual antimony trioxide in the product is smaller than 0.05%, and the whiteness value is larger than 95.

Description

Preparation method of high-end flame-retardant sodium pyroantimonate with controllable particle size Technical Field The invention relates to a preparation method of sodium pyroantimonate with controllable particle size for high-end flame retardance, belonging to the technical field of inorganic chemical synthesis. Background The current sodium pyroantimonate is used as an inorganic flame retardant synergist and an optical glass clarifier, the micro morphology and crystal structure determine the dispersibility, mechanical compatibility and optical performance of a final product in a polymer matrix, the main current industrial preparation process of Jiao Tisuan sodium is a liquid phase oxidation method, solid antimony trioxide powder is put into a reaction system containing sodium hydroxide and hydrogen peroxide for multiphase mixing reaction, the requirements on material performance are improved along with the high-end engineering plastics and the precision optical field, the traditional solid-liquid interface reaction mode shows dynamics limitation, the oxidation reaction only occurs at the interface of the surface of solid particles, the chemical heat released by the local reaction is difficult to dissipate rapidly, the temperature of a microenvironment rises instantaneously, the concentration of a sodium pyroantimonate product generated at the interface breaks through a critical value of burst nucleation in a very short time, a large number of micro crystal nuclei are generated unordered, and hot spots coincide with concentration points, so that the nucleation in the reaction system is difficult to decouple with empty high coupling in the growth process. In order to solve the above problems, although the industry tries to optimize the reaction path locally, simple feeding sequence adjustment or auxiliary introduction does not break through the bottleneck of heterogeneous reaction kinetics at all, for example, the Chinese patent of the invention with the authority of publication number of CN110015688B discloses a preparation method for reducing the granularity of sodium pyroantimonate, which adopts pre-oxidation reaction of antimony trioxide and hydrogen peroxide, and adds a surfactant and sodium hydroxide to precipitate so as to refine crystal grains. Therefore, changing the reaction dynamics mechanism, relieving the time-space coupling of oxidation reaction and crystallization nucleation, realizing the precise control of the particle size of sodium pyroantimonate and the intrinsic purification of crystal lattice, and becoming the technical problem to be solved by the invention. Disclosure of Invention In order to solve the problems in the background technology, the technical scheme of the invention is as follows, the preparation method of the sodium pyroantimonate with controllable particle size for high-end flame retardance comprises the following steps: Step S1, constructing a homogeneous metastable state precursor, adding antimony trioxide powder into a sodium hydroxide aqueous solution, completely dissociating solid phase particles under the conditions of heating and stirring and generating a coordination reaction until the system is converted into a transparent and clear sodium antimonite precursor solution, and immediately performing precise hot filtration operation on the sodium antimonite precursor solution to intercept insoluble mechanical impurities, thereby obtaining a homogeneous fluid filling without solid phase residues; Step S2, establishing a seed crystal induction field, preparing a base solution containing a preset number of primary seed crystals and having hydrogen peroxide concentration in a stoichiometric excess state in a reactor, and keeping the temperature of the base solution constant in a preset crystallization temperature interval to form an oxidant-rich receiving phase; Step S3, performing reverse lean solute dynamic locking, taking the homogeneous phase flowing liquid prepared in the step S1 as a disperse phase under the conditions of maintaining stirring and constant temperature, and injecting the homogeneous phase flowing liquid into the oxygen-enriched agent carrying phase in the step S2 in a continuous flow adding mode, wherein in the flowing adding process, a metastable zone edge pushing strategy is strictly performed, the molar excess state of hydrogen peroxide in the base liquid relative to antimonite ions is always maintained to construct a strong oxidation potential energy well, the adding rate of the homogeneous phase flowing liquid is controlled in real time, so that the instant supersaturation degree of sodium pyroantimonate generated by instant oxidation of antimonite ions entering the base liquid in a liquid phase is always maintained in a metastable zone which is lower than the burst nucleation critical value of a system and higher than the equilibrium solubility, and new solute molecules are directionally grown on the surface of the existing seed crystal unti