Textile grade sodium meta-antimonate surface modification process for improved dispersibility

Abstract

This invention relates to the fields of inorganic chemical engineering and textile auxiliaries, and discloses a surface modification process for textile-grade sodium metaantimonate to improve dispersibility. The process includes: adding sodium aluminate to a sodium metaantimonate suspension and stirring until dissolved to create an alkaline liquid environment in which tetrahydroxyaluminate ions are stably present; adding an aqueous solution of phenylphosphonic acid dropwise to this alkaline system for acid-base neutralization, controlling the hydrolysis of aluminum species using the acid release rate, and inducing in-situ generated aluminum hydroxyl species to coordinate with phenylphosphonate ions. This invention constructs an antimony-oxygen-aluminum-oxygen-phosphorus chemical hybrid coating layer without a phase interface on the surface of sodium metaantimonate through a specific acid-base coupling synchronous mineralization mechanism. This kinetically blocks the self-condensation aging path of aluminum species, improves the interfacial bonding force and thermal stability of the modified layer under high temperature and high shear conditions, and effectively solves the problems of thermal desorption and secondary agglomeration of sodium metaantimonate during melt spinning.

Description

Technical Field

[0001] This invention relates to a surface modification process for textile-grade sodium metaantimonate to improve dispersibility, belonging to the technical fields of inorganic chemicals and textile auxiliaries. Background Technology

[0002] Sodium metaantimonate, as an inorganic flame retardant synergist, has a high refractive index matching degree with polyester and nylon synthetic fiber matrices and is widely used in high-end textile fiber melt spinning processing. In melt spinning processes, inorganic powders need to withstand high temperatures and extremely high shear rates at the spinneret assembly. To improve the dispersibility and compatibility of sodium metaantimonate microparticle polymer melts, industrial processes typically employ wet surface chemical modification. The mainstream technical route follows a step-by-step assembly logic, adding inorganic aluminum salts such as aluminum sulfate and aluminum chloride to the sodium metaantimonate slurry, adjusting the pH value, and hydrolyzing and depositing aluminum hydroxide on the particle surface to form an intermediate layer as an inorganic anchor point. Organic phosphonic acid or silane coupling agents are introduced as organic modifiers to react with the aluminum hydroxide layer to construct a hydrophobic coating layer. This step-by-step process has long been a common practice in the industry because the operation units are independent and easy to control.

[0003] The development of spinning components towards ultra-fine denier and high irregularity places stringent requirements on the surface bonding strength of inorganic additives. Existing stepwise modification processes have inherent limitations. The core issue lies in the unavoidable time lag between the generation of inorganic precursors and the organic modification reaction. In stepwise processes, after aluminum salts undergo hydrolysis to form nascent hydrated alumina gel, even with extremely short process intervals or during aging, thermodynamically metastable aluminum hydroxyl species spontaneously and rapidly undergo oxygen bridging condensation, i.e., aging. This spontaneous microstructural evolution leads to an exponential decrease in the density of active hydroxyl sites on the gel layer surface over time. This results in insufficient reaction sites for subsequent addition of organophosphonic acids for chemical bonding, allowing them to adhere to the particle surface only through weak hydrogen bonds or physical adsorption. Furthermore, existing technologies, even for sodium pyroantimonate, primarily focus on improving purity or reducing free sodium salt content, failing to address the interfacial dispersion of inorganic particles in the high-shear environment of polymer melts. Regarding the challenge of thermal stability, for example, Chinese invention patent CN116854132B discloses a method for deep purification to prepare high-quality sodium pyroantimonate. This method focuses on deeply removing impurities such as chloride ions, free sodium ions, and heavy metals from sodium pyroantimonate by adjusting the reaction temperature and washing process, and controlling the particle size to below 1.2 μm, aiming to improve its initial purity as a flame retardant. However, this technical approach focuses on the purification and particle size control of the bulk material, without addressing the surface chemical modification of sodium metaantimonate, a different compound. It does not solve the fundamental technical bottleneck of insufficient interfacial bonding between additive particles and the polymer matrix during melt spinning, or thermal desorption and secondary agglomeration of the modified layer under high-temperature shear. The aforementioned existing technologies cannot provide technical inspiration for eliminating the aging delay of inorganic precursors in traditional stepwise wet modification processes, or for constructing high-bond-density, high-temperature-resistant antimony-oxygen-aluminum-oxygen-phosphorus chemical hybrid coating layers.

[0004] Therefore, the technical problem to be solved by this invention is how to eliminate the time lag between the precipitation of inorganic precursors and organic modification in the wet synthesis process, competitively inhibit the self-condensation aging of aluminum species, and construct a fully chemically bonded and stable hybrid coating layer. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A surface modification process for textile-grade sodium metaantimonate to improve dispersibility, comprising the following steps:

[0006] Step S1: Construct an alkaline precursor liquid environment. Disperse sodium metaantimonate filter cake in deionized water and prepare a suspension slurry with a solid content of 15wt% to 20wt%. Heat the suspension slurry and keep it at a constant temperature of 70°C to 80°C. Add sodium metaaluminate to the suspension slurry and stir until completely dissolved to establish an alkaline suspension system with a pH of 11.5 to 12.5 and aluminum species stably existing in the form of tetrahydroxyaluminate ions.

[0007] Step S2, acid-base coupled synchronous coordination reaction: Prepare an aqueous solution of phenylphosphonic acid with a mass concentration of 5% to 10% as an acidic reaction source. While maintaining the temperature of the suspension slurry and stirring, precisely add the aqueous solution of phenylphosphonic acid to the alkaline suspension system at a constant rate. Use the acidic release rate of phenylphosphonic acid to control the hydrolysis rate of tetrahydroxyaluminate ions. Continue adding until the pH value of the suspension slurry drops to the range of 6.5 to 7.0, then stop adding.

[0008] Step S3, lattice locking and post-processing: The slurry after the reaction in step S2 is kept at the reaction temperature for 30 to 60 minutes to mature. The slurry is filtered and washed with deionized water until the conductivity of the filtrate is less than 200 microsiemens per centimeter. The washed filter cake is dried at 105 degrees Celsius to constant weight to obtain modified sodium metaantimonate. During the pH decrease process in step S2, the aluminum hydroxyl species generated in situ coordinate with the phenylphosphonate group in the liquid phase at the moment of precipitation, and an antimony-aluminum-oxygen-phosphorus chemical hybrid coating layer without phase interface is grown on the surface of sodium metaantimonate.

[0009] Preferably, in step S1, the amount of sodium aluminate added is 0.5% to 1.5% based on the mass ratio of alumina to sodium antimonate, and the sodium aluminate is pre-dissolved in sodium hydroxide solution to form a clear sodium aluminate mother liquor before being added to the suspension slurry.

[0010] Preferably, in step S2, the dropping rate of the phenylphosphonic acid aqueous solution is controlled at 5 to 10 ml per minute, and the stirring linear velocity of the suspension slurry is controlled at 1.5 m / s to 2.5 m / s during the dropping process, so as to maintain a high concentration of phenylphosphonate surrounding aluminum species in the micro-mixing zone.

[0011] Preferably, the phenylphosphonic acid is selected from one of phenylphosphonic acid, 2-carboxyethylphenylphosphonic acid, or diphenylphosphonic acid, and the acidic reaction source does not contain any inorganic or organic acids other than phosphonic acid, ensuring that the decrease in pH of the system is entirely driven by the phosphonic acid species participating in the coordination reaction.

[0012] Preferably, in the acid-base coupling synchronous coordination reaction in step S2, the total amount of phenylphosphonic acid added and the molar ratio of aluminum in sodium aluminate must satisfy the following stoichiometric constraint, which is determined by the molar matching coefficient. definition: ,in, This represents the total number of moles of phenylphosphonic acid added. The total number of moles of aluminum in the added sodium aluminate; molar matching coefficient. The concentration is limited to the range of 0.95 to 1.05 to ensure that aluminum species in the liquid phase can be completely captured in situ by phenylphosphonate and converted into a chemically bonded state, while preventing excessive free phosphonic acid from forming small molecule plasticizers in subsequent spinning processes.

[0013] Preferably, before constructing the alkaline precursor liquid phase environment in step S1, the method further includes adding a dispersant to deionized water and pre-dissolving it. The dispersant is sodium polyacrylate or sodium hexametaphosphate, and the amount added is 0.1% to 0.3% of the mass of sodium antimonate. This dispersant is used to maintain the monodisperse state of the particles and inhibit bridging and agglomeration between particles during the reaction process in step S2.

[0014] Preferably, the modified sodium metaantimonate exhibits a thermal weight loss rate of less than 0.3% at 300 degrees Celsius, and in the dispersion stability test in dimethylacetamide solvent, the sedimentation volume ratio is greater than 98% after standing for 24 hours, indicating that the chemical hybrid coating layer has the characteristic of resisting thermal desorption at 300 degrees Celsius.

[0015] Preferably, in step S3, during the drying process, a gradient heating method is used, drying at 80 degrees Celsius for 2 hours to remove free water, and then heating to 120 degrees Celsius and holding for 2 hours to promote the dehydration condensation of surface coordination bonds and structural solidification.

[0016] Preferably, the process further includes a step of air jet milling the dried modified sodium antimonate, wherein the working fluid for air jet milling is superheated steam or compressed dry air, and the milling pressure is 0.6 MPa to 0.8 MPa, to depolymerize the soft agglomerates formed during the drying process.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. In the dispersible textile-grade sodium metaantimonate surface modification process, an acid-base coupling reaction system of sodium aluminate and phenylphosphonic acid is constructed. The acidity of phenylphosphonic acid directly neutralizes the alkalinity of aluminate, establishing a chemical competition mechanism to inhibit the self-condensation of aluminum species. This allows the aluminate to hydrolyze and generate highly active aluminum hydroxyl species, which are then instantly captured in situ by the high concentration of phosphonic acid groups in the liquid phase and undergo coordination reactions. Kinetically, this competitively blocks the oxygen-bridged condensation and aging pathway of the aluminum hydroxide precursor. The altered synthesis pathway leads to the formation of high-density chemical bonds between aluminum species and phosphonic acid groups in the modified layer, replacing the physical adsorption commonly found in existing stepwise processes. This solves the problem of failure of inorganic powder surface modification layers due to thermal desorption or shear peeling under subsequent melting processing conditions of 295°C to 300°C.

[0019] 2. Utilizing an organic acid-initiated in-situ hydrolysis and simultaneous mineralization process of inorganic precursors, a homogeneous, phase-separated organic-inorganic hybrid amorphous shell layer is induced to grow on the surface of sodium metaantimonate crystals. Compared with the traditional stepwise precipitation method, which forms an inorganic-organic composite structure with obvious interlayer interfaces, the hybrid shell layer integrates the inorganic matrix and organic functional groups through a continuous chemical bond network, eliminating structural weaknesses caused by differences in thermal expansion coefficients or insufficient interlayer bonding. The inherent structural stability ensures that the coating layer maintains its integrity when the product undergoes the high-shear rheological environment of the melt spinning assembly, shielding the polar sites on the sodium metaantimonate surface and preventing side reactions or agglomeration that clogs the spinneret assembly with the polymer matrix.

[0020] 3. Based on the nucleation and coordination-oriented growth mode induced by high-energy sites on the crystal surface, the modified components are efficiently utilized in stoichiometry on the surface of sodium antimonate particles. The hydrolysis and precipitation process of sodium aluminate is controlled by the dropwise addition of phenylphosphonic acid, and the reaction is limited to the active region at the solid-liquid interface. This suppresses the side reaction of homogeneous nucleation in the liquid phase to generate free aluminum hydroxide or aluminum oxide impurity particles. The mechanism not only significantly reduces the amount of unreacted phosphorus species in the mother liquor and reduces the load on the washing process, but also ensures that the final product has extremely low filtrate conductivity and excellent purity, meeting the strict impurity limit requirements of high-end textiles for inorganic additives. Attached Figure Description

[0021] Figure 1 This is a flow chart of the sodium metaantimonate surface modification process based on acid-base coupling synchronous coordination reaction of the present invention;

[0022] Figure 2 This is a comparison chart of key performance indicators of modified sodium antimonate under different processes and molar matching coefficients according to the present invention;

[0023] Figure 3 This is a schematic diagram of the microstructure of the modified sodium metaantimonate particles of the present invention. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to specific embodiments. The specific embodiments described in this section are only intended to explain the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0025] This invention provides a surface modification process for textile-grade sodium metaantimonate to improve dispersibility. Based on the acid-base coupling synchronous mineralization mechanism, an organic-inorganic hybrid coating layer is constructed in situ on the surface of inorganic powder by regulating the chemical kinetics process in the reaction system. The process mainly includes three stages: construction of an alkaline precursor liquid phase environment, acid-base coupling synchronous coordination reaction, and lattice locking and post-treatment.

[0026] In the stage of constructing the alkaline precursor liquid phase environment, the washed and purified sodium metaantimonate filter cake was dispersed in deionized water to prepare a solution with a mass fraction of [missing information]. to The suspension slurry system incorporates dispersants such as sodium polyacrylate or sodium hexametaphosphate, with the amount added being equal to the mass of sodium antimonate. to This is used to maintain the monodisperse state of the particles and to raise and maintain the slurry temperature at a constant level. to Under these temperature conditions, sodium aluminate is added to the slurry. The amount of sodium aluminate added is calculated based on the mass ratio of alumina to sodium antimonate. to Before addition, sodium aluminate is pre-dissolved in sodium hydroxide solution to form a clear mother liquor, ensuring that the tetrahydroxyaluminate ions are present after the slurry is added. The form exists stably, and at this time, the pH value of the system remains at [value missing]. to The strongly alkaline range, within which... The solubility product constant of the ions is lower than the precipitation threshold, ensuring that the aluminum source remains dissolved in the liquid phase in an ionic state and avoiding uncontrolled bulk precipitation.

[0027] In the acid-base coupling synchronous coordination reaction stage, phenylphosphonic acid was selected as a bifunctional reagent, and a solution with a mass concentration of [missing value] was prepared. to A phenylphosphonic acid aqueous solution was added dropwise to an alkaline suspension system at a constant rate, while maintaining the temperature and stirring conditions of the aforementioned suspension slurry. The dropping rate was controlled at [amount missing] per minute. ml to The stirring linear velocity of the suspension slurry is controlled at milliliters. meters per second to Meters per second is used to create a high-shear flow field in the micro-mixing region. During this process, the protons released by phenylphosphonic acid gradually neutralize the alkalinity of the system, leading to a decrease in the pH value of the local microenvironment. When the pH value enters the hydrolysis range of aluminum ions, The ions undergo in-situ dissociation, generating an active intermediate aluminum hydroxyl species. This hydrolysis process occurs directly in an environment surrounded by a high concentration of phenylphosphonate ions. The nascent aluminum species is captured by the phenylphosphonate ions at the moment of formation, and the two undergo a coordination condensation reaction to form... Chemically bonded structures, this kinetic control mechanism inhibits the formation of oxygen-bridged condensations between aluminum hydroxyl species. The aging pathway of the bonds causes the reaction to proceed along the direction of generating organic-inorganic hybrid substances. Phenylenic acid is continuously added dropwise until the pH of the suspension slurry drops to [value missing]. to The addition of phenylphosphonic acid should be stopped at the termination interval. To ensure the accuracy of the stoichiometric ratio of the reaction, the total amount of phenylphosphonic acid added should satisfy the molar ratio of aluminum in sodium aluminate with the molar matching coefficient. Constraints, namely ,in This represents the total number of moles of phenylphosphonic acid added. This represents the total number of moles of aluminum added.

[0028] During the lattice locking and post-processing stages, after the reaction is terminated, the slurry continues to mature at the reaction temperature. minutes to For several minutes, the surface coordination structure undergoes thermodynamic rearrangement and ordering, followed by slurry filtration and separation. The filter cake is then washed with deionized water in multiple countercurrent stages until the conductivity of the filtrate decreases to less than [value missing]. Micro Siemens per centimeter, that is To remove residual soluble sodium salt impurities from the system, the washed filter cake enters a gradient drying process. Drying under conditions Hours to remove physically adsorbed free water, temperature increased to and maintain During this high-temperature stage, surface chemical bonds undergo dehydration condensation reactions, enhancing... The crosslinking density and structural strength of the bonded network enable the final curing of the hybrid coating layer. The dried material is then processed by an air jet mill, using superheated steam or compressed air as the working fluid. Megapascal to Soft agglomerates formed during depolymerization and drying under pressure of MPa were used to obtain modified sodium metaantimonate powder, the surface of which was coated with a layer of thickness of [missing information]. nanometer to Nanoscale amorphous antimony-aluminum-oxygen-phosphorus chemical hybrid film, powder in dimethylacetamide solvent hourly settling volume ratio greater than .

[0029] Example 1: In a specific polyester industrial yarn melt spinning production scenario, the production line has long faced engineering challenges such as excessively rapid pressure rise of the spinneret assembly and fiber breakage. This production line uses polyethylene terephthalate (PET) chips as the matrix resin, and the spinning temperature is set to... The accuracy of the melt filter is The shear rate of the spinning assembly exceeds Under these conditions, conventional commercially available sodium metaantimonate flame retardants, due to insufficient thermal stability of their surface modification layer, undergo thermal desorption and peeling of the organic layer under high temperature and high shear, resulting in exposed inorganic particles that rapidly agglomerate, clogging the filter assembly and shortening the component replacement cycle to [missing information]. Within a few days, this severely impacts production efficiency and product quality consistency. To address this issue, this embodiment employs modified sodium metaantimonate prepared using the acid-base coupled simultaneous mineralization process of this invention as a substitute. The specific preparation process strictly follows the aforementioned implementation method: In the alkaline precursor liquid phase construction stage, sodium metaantimonate is dispersed in the aqueous phase and heated to [temperature missing]. ,join in Sodium aluminate, based on the mass ratio of alumina to sodium metaantimonate, was constructed with a pH value of [value missing]. And aluminum species A stable system; with rate of dripping A concentrated phenylphosphonic acid solution was used to precisely control the in-situ hydrolysis of aluminum species by utilizing the acid release rate, inducing instantaneous coordination bonding between nascent aluminum hydroxyl species and phenylphosphonate ions until the pH of the system decreased to a certain level. Finally, the finished product is obtained through gradient heating drying and airflow pulverization. This process, through precise matching of acid-base reaction kinetics, synchronizes the hydrolysis rate of the aluminum source with the coordination rate of phosphonate at the nanosecond level, forcing the reaction along the building block. The chemical bonding network proceeds in the direction of growth, thereby growing a uniform, dense, and phase-interface-free organic-inorganic hybrid coating layer in situ on the sodium metaantimonate surface.

[0030] The above-mentioned modified sodium metaantimonate was used as The mass fraction was prepared by melt blending with PET chips using a twin-screw extruder to produce masterbatch, which was then fed into a spinning production line and processed over a period of time. During a continuous operating cycle of 10 days, monitoring data showed that the linear growth rate of melt pressure before the spinning assembly decreased, and the assembly replacement cycle was extended to 10 days. For more than a day, no strand drift or breakage caused by inorganic particle agglomeration was observed. Scanning electron microscopy (SEM) analysis of the spinneret micro-orifice cross-section showed no obvious inorganic accumulation or coking. Furthermore, the residue retained on the melt filter surface was mainly environmental impurities rather than flame retardant agglomerates. The invention constructs… Hybrid bonding structures in It maintains extremely high structural integrity and interfacial bonding force in high-temperature shear flow fields, shields active sites on the surface of sodium antimonate, and solves the common industry problem of thermal desorption and secondary agglomeration.

[0031] Example 2: This example constructs a high-temperature shear rheology test platform simulating industrial melt spinning. The core platform includes a torque rheometer (HaakePolyLabQC) equipped with a precision temperature control system to simulate the thermomechanical environment of polymer melt during extrusion; and a melt filtration test unit equipped with a high-resolution melt pump and a precision pressure sensor to monitor the pressure change of the melt flowing through a standard filter screen in real time. The key performance index test methods are as follows: Filtration pressure value (FPV): determined according to EN13900-5 standard. Modified sodium metaantimonate was blended with PET chips to prepare masterbatch. Under constant temperature conditions, passing through at a constant flow rate Standard filter screen, record the pressure difference change before and after filtration, and calculate the FPV value (unit: Thermal desorption rate: Thermogravimetric analysis (TGA) was used to analyze the sample from room temperature to nitrogen atmosphere. Heat up to and maintain constant temperature Record the percentage of mass loss during the isothermal stage; Contact angle: Press the modified powder into tablets and use an optical contact angle meter to measure the contact angle of water droplets on the surface.

[0032] The design includes a multi-dimensional experimental scheme comprising a control group, the present invention sample group, and a parameter boundary exploration group. The control group setup includes: Control Group 1 (blank group): untreated sodium metaantimonate powder; Control Group 2 (traditional stepwise method): aluminum sulfate is first added to the sodium metaantimonate slurry to adjust the pH and precipitate aluminum hydroxide, followed by aging. Then, phenylphosphonic acid is added for further treatment; Control group 3 (physical mixing method): sodium antimonate and phenylphosphonic acid are simply physically dry-mixed without introducing aluminum source anchors; Sample group settings of this invention: Experimental groups 1-3: modified powders prepared by the acid-base coupling synchronous mineralization process of this invention, wherein the key variable is the molar matching coefficient of phenylphosphonic acid and aluminum. ( ), respectively set as , , During the experiment, the consistency of variables such as temperature, pH value, and stirring rate during the preparation process was strictly controlled. To simulate noise interference in a real industrial environment, all FPV tests were performed in superimposed layers. This was conducted against the backdrop of random pressure fluctuations.

[0033] Table 1: Test Results of Key Performance Indicators for Each Experimental Group

[0034]

[0035] Comparing control group 2 and experimental group 2, it can be seen that when the component dosages are exactly the same ( Under the premise of ), the sample (experimental group 2) prepared by the synchronous mineralization process of the present invention has an FPV value ( ) lower than traditional stepwise sample ( ),and The rate of thermal weight loss decreased by an order of magnitude (from Down to This invention achieves nanosecond-level synchronization of in-situ hydrolysis of aluminum species and coordination with phosphonic acid through acid-base kinetic control, constructing a phase-interface-free system. Chemical bonding structure; observing the data trends of experimental groups 1-3 reveals that, with... Value from Increase to As the contact angle increases, the FPV value drops sharply; however, when The value further increased to At that time, the FPV value actually rebounded (from Rise to Furthermore, the thermal weight loss rate increased slightly. This nonlinear performance inflection point phenomenon indicates that excessive phenylphosphonic acid ( These free acids did not participate in effective surface bonding; instead, they existed as free small molecules in the system. During high-temperature spinning, these free acids may act as plasticizers, causing abnormal fluctuations in melt viscosity. This experimental fact directly supports the molar matching coefficient. Limited to to The rationality and necessity within the scope.

[0036] Example 3: This example combines Figures 1 to 3 A process for surface modification of textile-grade sodium metaantimonate to improve dispersibility is described, such as... Figure 1 As shown, step S1 involves constructing an alkaline precursor liquid environment. This step involves pre-dissolving sodium aluminate mother liquor and dispersant in NaOH or sodium polyacrylate, and establishing an environment with a pH of 11.5 to 12.5 and aluminum species at a temperature of 70°C to 80°C. The system, existing in a stable form, proceeds to step S2 for a simultaneous acid-base coupling coordination reaction. This process involves the constant-rate dropwise addition of a 5% to 10% aqueous solution of phenylphosphonic acid, utilizing key process control, namely the molar matching coefficient. Controlled within 0.95≤ Within the range of ≤1.05, in-situ hydrolysis and coordination are synchronized and formed. After bonding and reaction, step S3 is performed for lattice locking and washing, including heat preservation for 30 to 60 minutes and countercurrent washing, followed by gradient temperature drying, removal of free water at 80°C and promotion of coordination bond condensation and solidification at 120°C. Finally, the soft agglomerates are depolymerized by airflow at a pressure of 0.6 to 0.8 MPa to obtain modified sodium antimonate powder with an amorphous antimony-aluminum-oxygen-phosphorus chemical hybrid film on the surface.

[0037] like Figure 2 As shown, the left vertical axis represents the FPV value in bar / g, the right vertical axis represents the thermal weight loss rate at 300℃ in %, and the horizontal axis covers the untreated, traditional stepwise method, physical mixing method, and the simultaneous method of this invention at different temperatures. The test groups were divided into groups with values ​​of 0.80, 1.00, and 1.20. Data showed that the untreated group had the highest FPV value but extremely low thermal weight loss. While traditional stepwise and physical mixing methods reduced FPV values, they were accompanied by high thermal weight loss rates. In contrast, the simultaneous method of this invention... When =1.00, it simultaneously achieves the lowest FPV value (close to 0) and the lowest thermal weight loss rate, and when When the deviation reaches 0.80 or 1.20, both indicators show varying degrees of upward trend; for example... Figure 3 As shown in the schematic diagram, this microstructure illustrates the core-shell structure of modified sodium metaantimonate, where the core is a sodium metaantimonate crystal core, i.e. The periphery is through A chemically bonded interface consisting of bonds connects a hybrid coating layer with a thickness of 5 to 15 nm, the interior of which is composed of… The network is composed of positively charged symbols, and the outermost layer has phenyl external functional groups that provide steric hindrance, forming a dense protective structure.

[0038] Example 4: This example aims to provide a systematic and standardized engineering calibration procedure. This procedure not only confirms the key role of phenylphosphonic acid addition in the integrity and thermal stability of the modified layer, but also quantitatively reveals the potential interference mechanism of excessive organic acid on the melt rheological properties under high-temperature shear fields. To determine the optimal range, a system based on molar matching coefficients is constructed. ( A gradient experimental scheme was used to prepare a series of modified sodium antimonate samples. During the preparation process, except for the amount of phenylphosphonic acid added as the only variable, all other process parameters were strictly controlled to remain constant, including the reaction temperature. The pH value for stopping the addition is set to... In addition to factors such as stirring rate, the amount of phenylphosphonic acid added is set to cover five gradient levels covering under-addition, stoichiometric ratio, and excess regions, corresponding to... The values ​​are respectively , , , and .

[0039] Standardized performance tests were performed on the above-mentioned samples using a thermogravimetric analyzer (TGA). The thermal weight loss rate was measured, which characterizes the thermal stability of the modified layer. Simultaneously, the filtration pressure value (FPV) was determined through melt filtration testing, which characterizes the dispersion of particles in the polymer melt. The test results showed that when… Value from Increase to At that time, the thermal weight loss rate from Reduce to FPV value from sharp drop to As the coordination ratio approaches the stoichiometric ratio, surface coverage and bonding strength increase simultaneously. The value continued to increase to and At that time, although the thermal weight loss rate remained at a low level (respectively... and However, the FPV value showed a reverse upward trend, increasing to [missing information]. and Based on a comprehensive analysis of the above nonlinear variation patterns, the optimal working window for the addition amount of phenylphosphonic acid was determined. Within this window ( Between to (between), the system can simultaneously satisfy the requirement that the thermal weight loss rate is less than And the FPV value is less than The dual performance indicators confirm the rationality of the molar matching coefficient limit range, providing direct engineering basis for precise material feeding in industrial production.

[0040] Example 5: To ensure the reproducibility and consistency of modification effects of the acid-base coupled simultaneous mineralization process on different batches of sodium metaantimonate raw materials, this example establishes a standardized pre-calibration procedure for the fluctuations in the hydroxyl density and alkaline release characteristics of the raw material surface. This procedure determines the acid consumption potential of the sodium metaantimonate filter cake of the batch to be treated. The specific method is as follows: a certain mass of filter cake is dispersed in deionized water, and a standard concentration of phenylphosphonic acid solution is added dropwise at a constant rate under constant temperature and stirring speed. At the same time, the pH change curve of the system is monitored in real time. By analyzing the extreme point of the first derivative of the curve, the standard acid amount required for the system to decrease from the initial alkalinity to the target reaction endpoint pH value is determined. Based on this benchmark value, combined with the molar matching coefficient... The range of fine-tuning parameters for the concentration or dropping rate of the phenylphosphonic acid solution in actual production compensates for differences in chemical activity between batches of raw materials. This calibration step ensures that the acid-base neutralization rate in the reaction system matches the hydrolysis-coordination kinetics window of aluminum species, thus guaranteeing the homogeneity and stability of the modified layer structure.

[0041] To address the reactor scaling and mass transfer efficiency degradation issues that may occur in industrial continuous production scenarios, this embodiment constructs a process control procedure based on real-time conductivity monitoring. During the acid-base coupling synchronous coordination reaction and subsequent lattice locking stages, online conductivity sensors continuously collect conductivity data of the suspended slurry. Since the morphological transformation of aluminum species is accompanied by conductivity changes, a set of characteristic conductivity thresholds and change rate criteria are set. When the real-time monitoring data deviates from the preset standard trajectory, the control system automatically triggers compensatory adjustments to the stirring linear speed or the heat treatment and ripening time. If the conductivity decrease rate is lower than the preset threshold, indicating that precipitation transformation is hindered, the system will automatically increase the stirring speed to enhance micro-mixing and mass transfer. This closed-loop control mechanism based on real-time feedback of process parameters avoids the impact of equipment state drift on product quality, ensuring that the conductivity of the final product filtrate remains stable at less than [value missing]. Within the range.

[0042] Example 6: This example provides a standardized engineering calibration procedure for determining the optimal reaction kinetic parameters of sodium aluminate and phenylphosphonic acid in the sodium antimonate surface modification process. This addresses the nonlinear influence of reaction rate control on the microstructure and final properties of the modified layer. The procedure confirms the importance of matching the acid-base neutralization rate with the hydrolysis-coordination rate of aluminum species and reveals the amplification effect of the reaction kinetic parameters at different process scales. To determine the optimal kinetic parameters, a method based on the droplet acceleration constant is constructed. A gradient experimental scheme was used to prepare a series of modified sodium metaantimonate samples. During the preparation process, except for the dropping rate of the phenylphosphonic acid solution, which was the only variable, all other process parameters were strictly controlled to remain constant, including the reaction temperature. Mohr matching coefficient Set as and the stirring linear speed is maintained at The dropping rate of the phenylphosphonic acid solution was set to five gradient levels covering slow, medium, and fast ranges, with corresponding dropping times of [missing information]. , , , and .

[0043] Standardized performance tests were performed on the above-mentioned samples. Transmission electron microscopy (TEM) was used to observe the microstructure of the modified layer to characterize its uniformity and density. Simultaneously, melt filtration pressure (FPV) was measured to characterize the particle dispersion in the polymer melt. The test results showed that when the dropping time increased from […], […]. shortened to At that time, TEM images showed that the modified layer changed from a loose porous structure to a dense continuous film, and the FPV value increased from... Reduce to This trend indicates that as the dropping rate increases, the matching degree between the acid-base neutralization rate and the hydrolysis rate of aluminum species improves, which is conducive to the formation of a dense chemical bond structure. When the dropping time is further shortened... and At that time, TEM images showed localized aggregation and delamination in the modified layer, and the FPV value showed a reversal upward trend, increasing to [values ​​to be filled in]. and Based on a comprehensive analysis of the above nonlinear variation patterns, the optimal working window for the dropping acceleration rate of the phenylphosphonic acid solution was determined. Within this window (the dropping time is between...), the optimal working window is determined. to (between), the system can simultaneously satisfy the requirements of dense and uniform modified layer and FPV value less than Dual performance indicators.

[0044] Example 7: Before constructing the alkaline precursor liquid phase environment, the raw material alkali release standard was calibrated. A quantitative sample of sodium metaantimonate filter cake was extracted, dispersed in deionized water, and heated to the process set temperature. A standard concentration of phenylphosphonic acid solution was added dropwise at a constant rate and the results were recorded. The variation curve and the extreme point of the first derivative of the analytical curve determine the actual acid consumption when the raw materials reach the reaction equivalence point. The measured value is input into the central control system to correct the mass ratio of sodium aluminate to phenylphosphonic acid, eliminating the stoichiometric ratio deviation caused by the difference in free alkali content on the raw material surface, and ensuring that the aluminum species in the liquid phase are strictly in accordance with the reaction equivalence point. Preset constraints are fully captured; the acid-base coupling synchronous coordination reaction stage adopts a flow field confirmation mechanism based on conductivity differential response, and the reactor is equipped with a serrated disc type or an open turbine type high-shear impeller, with the stirring linear velocity set. to The system utilizes an online conductivity sensor to monitor the local concentration gradient at the moment of droplet addition in real time. If the conductivity fluctuation variance exceeds the preset steady-state threshold, it triggers a stirring speed compensation command or reduces the acid droplet acceleration rate until the conductivity change curve returns to the linear smooth range. The fluid dynamics control logic ensures that a high concentration of phenylphosphonate is maintained around the aluminum hydroxyl species precipitation point when the geometric dimensions of the reaction vessel change.

[0045] Reaction endpoint control implementation based on Hysteresis adaptive dosing strategy, system Value dropped to During the critical interval, the continuous flow dripping mode of the phenylphosphonic acid solution is switched to a pulsed micro-replenishment mode. The amount of acid added during the pulse cycle is increased from the previous cycle. The response slope determines that the pulse interval must be maintained at least [a certain value]. The pure stirring equilibrium time is maintained until the system stops dropping. Within minutes Value remains stable to The target range has no rebound, preventing local over-acidity from causing disordered crystal form of aluminum-phosphorus precipitates or loose coating structure, and establishing thermodynamic boundary conditions for dense growth of amorphous antimony-aluminum-phosphorus chemical hybrid films.

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A surface modification process for textile-grade sodium metaantimonate to improve dispersibility, characterized in that, Includes the following steps: Step S1: Construct an alkaline precursor liquid environment. Disperse sodium metaantimonate filter cake in deionized water and prepare a suspension slurry with a solid content of 15wt% to 20wt%. Heat the suspension slurry and keep it at a constant temperature of 70°C to 80°C. Add sodium metaaluminate to the suspension slurry and stir until completely dissolved to establish an alkaline suspension system with a pH of 11.5 to 12.5 and aluminum species stably existing in the form of tetrahydroxyaluminate ions. Step S2, acid-base coupled synchronous coordination reaction: Prepare an aqueous solution of phenylphosphonic acid with a mass concentration of 5% to 10% as an acidic reaction source. While maintaining the temperature of the suspension slurry and stirring, precisely add the aqueous solution of phenylphosphonic acid to the alkaline suspension system at a constant rate. Use the acidic release rate of phenylphosphonic acid to control the hydrolysis rate of tetrahydroxyaluminate ions. Continue adding until the pH value of the suspension slurry drops to the range of 6.5 to 7.0, then stop adding. Step S3, lattice locking and post-processing: The slurry after the reaction in step S2 is kept at the reaction temperature for 30 to 60 minutes to mature. The slurry is filtered and washed with deionized water until the conductivity of the filtrate is less than 200 microsiemens per centimeter. The washed filter cake is dried at 105 degrees Celsius to constant weight to obtain modified sodium metaantimonate. During the pH decrease process in step S2, the aluminum hydroxyl species generated in situ coordinate with the phenylphosphonate group in the liquid phase at the moment of precipitation, and an antimony-aluminum-oxygen-phosphorus chemical hybrid coating layer without phase interface is grown on the surface of sodium metaantimonate.

2. The surface modification process for textile-grade sodium metaantimonate to improve dispersibility according to claim 1, characterized in that, In step S1, the amount of sodium aluminate added is 0.5% to 1.5% based on the mass ratio of alumina to sodium antimonate, and the sodium aluminate is pre-dissolved in sodium hydroxide solution to form a clear sodium aluminate mother liquor before being added to the suspension slurry.

3. The surface modification process for textile-grade sodium metaantimonate to improve dispersibility according to claim 1, characterized in that, In step S2, the dropping rate of the phenylphosphonic acid aqueous solution is controlled at 5 to 10 ml per minute, and the stirring linear velocity of the suspension slurry is controlled at 1.5 m / s to 2.5 m / s during the dropping process, so as to maintain a high concentration of phenylphosphonate surrounding aluminum species in the micro-mixing zone.

4. The surface modification process for textile-grade sodium metaantimonate to improve dispersibility according to claim 1, characterized in that, Phenylophosphonic acid is selected from one of phenylphosphonic acid, 2-carboxyethylphenylphosphonic acid, or diphenylphosphonic acid. The acidic reaction source does not contain any inorganic or organic acids other than phosphonic acid, ensuring that the decrease in pH of the system is entirely driven by the phosphonic acid species participating in the coordination reaction.

5. The surface modification process for textile-grade sodium metaantimonate to improve dispersibility according to claim 1, characterized in that, In step S2, the acid-base coupled synchronous coordination reaction, the total amount of phenylphosphonic acid added and the molar ratio of aluminum in sodium aluminate must satisfy the following stoichiometric constraint, which is determined by the molar matching coefficient. definition: ,in, This represents the total number of moles of phenylphosphonic acid added. The total number of moles of aluminum in the added sodium aluminate; molar matching coefficient. The concentration is limited to the range of 0.95 to 1.05 to ensure that aluminum species in the liquid phase can be completely captured in situ by phenylphosphonate and converted into a chemically bonded state, while preventing excessive free phosphonic acid from forming small molecule plasticizers in subsequent spinning processes.

6. The surface modification process for textile-grade sodium metaantimonate to improve dispersibility according to claim 1, characterized in that, Before constructing the alkaline precursor liquid environment in step S1, a dispersant is added to deionized water and pre-dissolved. The dispersant is sodium polyacrylate or sodium hexametaphosphate, and the amount added is 0.1% to 0.3% of the mass of sodium antimonate. It is used to maintain the monodisperse state of the particles and inhibit the bridging and agglomeration between particles during the reaction process in step S2.

7. The surface modification process for textile-grade sodium metaantimonate to improve dispersibility according to claim 1, characterized in that, The modified sodium metaantimonate exhibits a thermal weight loss rate of less than 0.3% at 300°C and a sedimentation volume ratio greater than 98% after standing for 24 hours in a dimethylacetamide solvent dispersion stability test, indicating that the chemical hybrid coating layer has the characteristic of resisting thermal desorption at 300°C.

8. The surface modification process for textile-grade sodium metaantimonate to improve dispersibility according to claim 1, characterized in that, In step S3, during the drying process, a gradient heating method is adopted. The temperature is increased to 80 degrees Celsius for 2 hours to remove free water, and then the temperature is increased to 120 degrees Celsius and held for 2 hours to promote the dehydration condensation of surface coordination bonds and structural solidification.

9. The surface modification process for textile-grade sodium metaantimonate to improve dispersibility according to claim 1, characterized in that, The process also includes a step of air jet milling the dried modified sodium antimonate. The working medium for air jet milling is superheated steam or compressed dry air, and the milling pressure is 0.6 MPa to 0.8 MPa, which depolymerizes the soft agglomerates formed during the drying process.

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