Green chelating agent mgda product and mgda synthesis and granulation process

Abstract

The application discloses a kind of green chelating agent MGDA product, including by glycine sequentially by sodium bromopropionate, sodium bromoacetate two-step substitution method synthesis MGDA solution or MGDA cream or MGDA granules;The synthesis of MGDA is that glycine is formulated into sodium glycine solution, substitution reaction is carried out with sodium bromopropionate solution, sodium bromoacetate solution in turn, the water content is reduced to 40~45%w / w by the reaction liquid under inert gas atmosphere at 110~120 DEG C evaporation concentration makes, again cooling and removing impurities, obtain MGDA solution;And / or, continue to concentrate to cream under inert gas atmosphere by MGDA solution;And / or, after adding auxiliary to MGDA cream, continue to remove moisture and granulation, obtain MGDA granules.The green chelating agent MGDA product of the application not only has high chelating activity and product quality, but also can eliminate environmental protection risk of production process from root, can provide a variety of forms of high-end MGDA series products for washing, daily chemical, hygiene protection and other industries, promote the application of green chelating agent MGDA in high-end daily necessities.

Description

Technical Field

[0001] This invention relates to the field of green chelating agent production technology, specifically to a green chelating agent MGDA product, and the synthesis and granulation process of MGDA. Background Technology

[0002] Chemicals play a vital role in human production and daily life. They are generally categorized by function into daily chemical products, industrial chemicals, and agricultural chemicals, with daily chemical products being the most frequently used and subject to human contact. The production and use of chemicals often require large amounts of water. However, hard water ions such as calcium and magnesium can cause functional degradation of the main surfactant components in chemicals, reducing their effectiveness. Therefore, chelating agents are added to chemical formulations to maintain the stability of chemicals during manufacturing, storage, transportation, and use.

[0003] Chelating agents are functional additives that can chelate hard water ions such as calcium and magnesium in water to reduce their impact on the efficacy of chemicals. Their role extends throughout the entire product lifecycle, from production and storage to use. There are many types of chelating agents; broadly speaking, anything that can reduce the impact of hard water ions like calcium and magnesium can be called a chelating agent, including organophosphates and polycarboxylic acids. However, with increasingly stringent global environmental regulations and rising consumer demand for green and healthy products, the environmental and safety risks of some chelating agents are becoming increasingly apparent. For example, the use of phosphorus-containing chelating agents can lead to eutrophication, causing cyanobacterial blooms and water quality deterioration, and their use has been restricted in many countries. Furthermore, some synthetic polycarboxylic acid chelating agents are being gradually banned or restricted due to their slow biodegradability (such as EDTA and DTPA) or potential carcinogenicity (such as NTA). Therefore, green alternatives to chelating agents have become a core direction for the industry's sustainable development.

[0004] Trisodium methylglycine diacetate (MGDA) is an environmentally friendly small-molecule chelating agent with excellent toxicological safety and biodegradability, making it widely applicable in various industrial fields and an ideal alternative to traditional chelating agents. In the daily chemical industry, MGDA can be used as a core building block in phosphate-free detergents, significantly improving detergency and preventing soap rancidity, discoloration, and redeposition of dirt. It can also be used in phosphate-free dishwashing formulations to enhance rinsing effectiveness and reduce residue. Furthermore, it can be applied in cosmetics and personal care products. However, MGDA also has certain limitations in its application in daily chemical products: First, most daily chemical products are in fluid paste or granular form, while MGDA is often a liquid product, affecting its application in granular daily chemical products and requiring granulation before use. Second, MGDA's structure contains many unsaturated bonds, making it susceptible to damage from high temperatures and oxidation during conventional granulation processes, thus reducing its effectiveness. Third, MGDA is an alkaline organic salt; its material properties mean it easily transforms from a solid to a fluid under high temperatures, increasing the difficulty of granulation, while at low temperatures, excessive moisture remains in the solid, affecting its stability. To address the aforementioned issues, major manufacturers typically employ processes such as spray drying combined with extrusion granulation, spray drying combined with fluidized bed granulation, and crystallization separation combined with fluidized bed granulation to obtain the desired granules. These processes are complex and costly. Furthermore, the combined use of MGDA with other aminopolycarboxylic acid green chelating agents, such as tetrasodium iminodisuccinate (IDS), tetrasodium glutamate diacetate (GLDA), tetrasodium aspartate diacetate (ASDA), and ethylenediaminedisuccinic acid (EDDS), also suffers from the aforementioned drawbacks.

[0005] Furthermore, there are conflicts between the current mainstream synthesis process of MGDA and market requirements and regional regulations. Specifically, firstly, the traditional hydrogen cyanide process requires the use of highly toxic chemicals such as hydrogen cyanide and its salts. Although there have been improvements, such as using hydrogen cyanide to synthesize IDA first and then continuing to synthesize MGDA, the use of hydrogen cyanide is still unavoidable. This results in hydrogen cyanide residues and the generation of prohibited / restricted products such as NTA byproducts, which greatly weakens the green environmental protection and safety reliability of MGDA. Secondly, the alanine-chloroacetic acid method has many side reactions, generating a large amount of glycolate and a large amount of sodium chloride that is difficult to remove (the solubility of sodium chloride is close to that of MGDA, making it difficult to remove). This results in a high impurity content in the product, which limits the application of the above-mentioned process products, especially in chlorine-sensitive environments (such as dishwashers and washing machines).

[0006] Therefore, improving and optimizing the synthesis process of MGDA, solving the shortcomings of the existing process, enhancing the performance of MGDA products, and expanding its application in the daily chemical industry and high-end daily necessities are among the development directions for MGDA production. Summary of the Invention

[0007] This invention addresses the shortcomings of existing MGDA synthesis processes, such as the use or generation of prohibited or restricted substances during production and the impact of sodium chloride impurities on product quality. Furthermore, it addresses the influence of melting point issues on material activity during MGDA granulation and application, providing a green chelating agent MGDA product and a synthesis and granulation process for MGDA. By modifying the raw materials and synthesis process of MGDA, this invention achieves the acquisition of green chelating agent MGDA solutions, pastes, and granules suitable for industries such as detergents, daily chemicals, and hygiene products while retaining the high efficiency of MGDA.

[0008] To achieve the above objectives, the present invention provides a green chelating agent MGDA product, comprising an MGDA solution, MGDA paste, or MGDA granules synthesized from glycine via a two-step substitution method involving sodium bromopropionate and sodium bromoacetate. The synthesis of MGDA involves preparing a sodium glycine solution, which is then reacted sequentially with sodium bromopropionate solution and sodium bromoacetate solution. The resulting reaction solution is evaporated and concentrated at 110-120°C under an inert gas atmosphere to reduce the water content to 40-45% w / w. The solution is then cooled to remove impurities, yielding an MGDA solution. Alternatively, the MGDA solution is further concentrated to a paste under an inert gas atmosphere. Or, an additive is added to the MGDA paste, followed by further water removal and granulation to obtain MGDA granules.

[0009] To address the quality defects and environmental issues associated with the synthesis of existing MGDA products, this invention modifies the raw materials and process of MGDA synthesis. It innovatively employs a two-step substitution synthesis of MGDA using glycine with sodium bromopropionate and sodium bromoacetate. Following this, evaporation and concentration, along with cooling and impurity removal at temperatures below MGDA's conventional melting point (110-120°C) under an inert atmosphere, effectively protect the unsaturated bonds in the MGDA molecular structure, ensuring its green biodegradability and chelating activity. This process also efficiently separates impurities such as bromides and chlorides, improving product quality and eliminating environmental risks at the source. The resulting MGDA solution provides a foundation for the subsequent preparation of highly active MGDA pastes and MGDA granules. This allows for the provision of diverse, high-quality, and highly active MGDA raw materials for green chelating agent MGDA products needed in the detergent, daily chemical, and hygiene industries, promoting the application of green chelating agent MGDA in high-end daily necessities.

[0010] As a limitation of the above technical solutions, the sodium glycinate solution is obtained by reacting a solution obtained by completely dissolving glycin with sodium hydroxide at a reaction temperature <95℃; and / or, the sodium bromopropionate solution is obtained by reacting a microemulsion obtained by dissolving sodium bromopropionate with sodium hydroxide at a reaction temperature <85℃; and / or, the sodium bromoacetate solution is obtained by reacting a microemulsion obtained by dissolving sodium bromoacetate with sodium hydroxide at a reaction temperature <85℃.

[0011] As a limitation of the above technical solution, the substitution synthesis reaction temperature of sodium glycinate solution and sodium bromopropionate solution is 70~80℃, and the molar ratio of sodium bromopropionate to glycine is 1~1.1:1; the substitution synthesis reaction temperature of sodium bromoacetate solution and sodium bromoacetate solution is 70~80℃, and the molar ratio of sodium bromopropionate to glycine is 1~1.1:1.

[0012] Further refine the preparation of each raw material solution, the ratio of raw material dosage, and the reaction temperature in the MGDA synthesis process, and optimize the MGDA synthesis reaction process and results.

[0013] As a limitation of the above technical solution, the MGDA solution is concentrated by triple-effect evaporation at 110~120℃, 120~130℃ and 130~140℃ in sequence to obtain an MGDA paste with a water content of 20~30%.

[0014] Concentrating MGDA solution into a paste through multi-effect evaporation not only improves concentration efficiency and saves energy costs, but also effectively protects the molecular structure and activity of MGDA and reduces the impact of moisture on the material.

[0015] As a limitation of the above technical solution, an additive is added to the MGDA paste, and after full emulsification, moisture is removed and granulation is performed. Then, a hardness modifier is sprayed onto the surface of the granules to obtain MGDA granule products.

[0016] As a limitation of the above technical solution, the additives include melting point regulators and heat-oxidation stabilizers; preferably, the amount of melting point regulator added is 1.0~2.5% of the mass of MGDA, and the melting point regulator is a substance with a melting point below 140℃, more preferably potassium hydroxide, alkanolamines, or ammonium formate; the amount of heat-oxidation stabilizer added is 0.2~0.4% of the mass of MGDA, and the heat-oxidation stabilizer is industrial vitamin C or a mixture of industrial vitamin C and glucose, with a mass ratio of industrial vitamin C to glucose of 1~3:1; the amount of hardness regulator added is 3~6‰ of the mass of MGDA, and it is selected as an inorganic water-soluble silicate or water-dispersible silica.

[0017] To further develop low-melting-point MGDA granules, the MGDA paste, after impurity removal and multi-effect evaporation and concentration, is modified with additives including melting point adjusters and heat and oxygen stabilizers. Then, it is granulated in a high tower to effectively reduce the damage to the active material caused by the granulation environment. Finally, the granules are reinforced by spraying to improve their hardness, surface moisture absorption, and flowability.

[0018] Melting point regulators lower the melting point of materials from 140℃ or above to 115-125℃. Their effect is twofold: first, the low melting point of alkaline substances forms molten "nuclei" in the system, causing a heat island effect that lowers the overall melting point; second, a chemically induced spatial structure reaction occurs between the green chelating agent and the melting point regulator, forming substances with even lower melting points. Heat and oxygen stabilizers reduce the oxidation of materials by residual high-temperature oxygen in conditions away from an inert atmosphere or in high-tower granulators, further enhancing the protection of material activity. Hardness regulators ensure the skeletal hardness of low-melting-point materials.

[0019] As a limitation of the above technical solution, the bromide content (calculated as bromine) in the green chelating agent MGDA product shall not exceed 300 mg / kg, the chloride content (calculated as chlorine) shall not exceed 100 mg / kg, and it shall not contain the prohibited substance NTA; and / or, The green chelating agent MGDA product also includes aminopolycarboxylic acid green chelating agents other than MGDA. Preferably, the mass content of the aminopolycarboxylic acid green chelating agents other than MGDA (i.e., the percentage of the mass of other aminopolycarboxylic acid green chelating agents added to the total amount of the green chelating agent MGDA product) does not exceed 20% of the mass content of MGDA. More preferably, the aminopolycarboxylic acid green chelating agents other than MGDA are selected from at least one of tetrasodium iminodisuccinate, tetrasodium glutamate diacetate, tetrasodium aspartate diacetate, and ethylenediaminedisuccinate.

[0020] The green chelating agent MGDA obtained by this invention has an impurity content that meets the industry's requirements for high-end quality. It can also be compounded with other aminopolycarboxylic acid green chelating agents to form composite green chelating agent products to adapt to a wide range of chemical applications.

[0021] In addition, the present invention also provides a synthesis process for MGDA, including the following synthesis steps: Preparation of reaction solutions: Add deionized water to reaction vessel A, add glycine under stirring and cooling conditions, and after it is completely dissolved, add sodium hydroxide. Control the reaction temperature <95℃. After the reaction is complete, obtain reaction solution A; Add deionized water and sodium bromoacetate to reaction vessel B, and after it is dissolved into a microemulsion under stirring and cooling conditions, add sodium hydroxide. Control the reaction temperature <85℃. After the reaction is complete, obtain reaction solution B; Add deionized water and sodium bromopropionate to reaction vessel C, and after it is dissolved into a microemulsion under stirring and cooling conditions, add sodium hydroxide. Control the reaction temperature <85℃. After the reaction is complete, obtain reaction solution C. Preferably, the concentration of the solution prepared by glycine and deionized water is 51±1% w / w, and the molar ratio of sodium hydroxide to glycine is 1:1.3~1.5. Preferably, the concentration of the microemulsion prepared by sodium bromoacetate or sodium bromopropionate and deionized water is 52-65% w / w, and the molar ratio of sodium hydroxide to sodium bromoacetate or sodium bromopropionate is 1:1.1-1.4. b. Two-step substitution synthesis reaction: Heat each reaction solution to 70~80℃, pump reaction solution C into reaction vessel A, and keep the reaction temperature for 11~13h after complete addition; continue to pump reaction solution B into reaction vessel A, and keep the reaction temperature for 15~21h after complete addition. The filtered reaction solution is concentrated by evaporation at 110~120℃ under an inert gas atmosphere. After controlling the water content to reach 40~45%w / w, the temperature is lowered to 20~25℃, and then allowed to stand for 10~12h to promote the precipitation of impurities. Solid-liquid separation is performed to obtain MGDA solution.

[0022] As a limitation of the above technical solution, the MGDA solution is further concentrated and dehydrated to obtain an MGDA paste; the concentration and dehydration process is as follows: The MGDA solution was concentrated under a nitrogen atmosphere by triple-effect evaporation at 110~120℃, 120~130℃ and 130~140℃ to obtain an MGDA paste with a water content of 20~30% w / w. The nitrogen containing water vapor during the evaporation process was recovered, and the water vapor was removed before recycling.

[0023] This invention also provides a granulation process for MGDA, which adds modification and granulation steps to the synthesis steps described above to obtain MGDA particles; the modification and granulation steps are operated as follows: A saturated solution of melting point regulator and heat-oxidation stabilizer is added sequentially to the MGDA paste. Then, the paste is mixed at medium and high speed and degassed by ultrasonication to obtain a fully emulsified paste. The paste is then granulated by removing moisture and passing it through a high-tower granulator. During the cooling stage, a hardness regulator is sprayed onto the surface of the granules to control the particle size of the granules after spraying to be between 20μm and 2mm, thus obtaining MGDA granules. Preferably, the medium-to-high speed mixing rate is not less than 1500 r / min, and / or the hardness modifier is applied using a directional, continuous spraying method, with a coating coverage of not less than 80% on the particle surface, and the obtained MGDA particle strength is 5~20 N / mm. 2 .

[0024] The synthesis and granulation process of MGDA in this invention has the advantages of simple steps and safe operation. The obtained chelating agent MGDA product has high activity, low melting point, good storage and transportation resistance, and is easy to mix. Specifically, the two-step substitution synthesis process, combined with low-temperature concentration, impurity removal, multi-effect evaporation concentration under an inert atmosphere, and granulation treatment, not only avoids the environmental risks of conventional processes, but also ensures the chelating ability and quality of MGDA product, and reduces the energy consumption of moisture removal, thus greatly optimizing and improving the MGDA production process.

[0025] In summary, this invention utilizes glycine with sodium bromopropionate and sodium bromoacetate to synthesize MGDA via a two-step substitution method. Then, through low-temperature concentration, impurity removal, multi-effect evaporation concentration, and granulation under an inert atmosphere, a series of green chelating agent MGDA products are obtained. These products are free from corrosive substances, prohibited / restricted substances (NTA), and their bromide and chloride content meets high-end quality requirements. They are suitable for the high standards of chemicals in industries such as detergents, daily chemicals, and hygiene products. Furthermore, the production process is safe and environmentally friendly, and it plays a positive role in promoting the development of green chelating agents. Attached Figure Description

[0026] Figure 1 The image shows the DSC melting point spectrum of the MGDA particle sample from Example 1.

[0027] Figure 2 The infrared spectrum is shown for the MGDA particle sample of Example 1.

[0028] Figure 3 The image shows the DSC melting point spectrum of the MGDA sample in Comparative Example 1.

[0029] Figure 4 The infrared spectrum of the MGDA sample in Comparative Example 1 is shown.

[0030] Figure 5 This is a photograph of the MGDA particle sample synthesized in this invention. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Unless otherwise specified, the experimental methods described below are conventional methods; the raw materials or test materials used are typical products purchased from the market, unless otherwise specified. In the quantitative experiments of the following examples and comparative examples, three replicate experiments were conducted, and the results were averaged.

[0033] The hardness of MGDA particles was determined using the standard ASTM D5230, and the average particle size was determined using a Malvern 3000 laser particle size analyzer. Example 1

[0034] A green chelating agent, MGDA product I, is composed of MGDA particles, and the specific production process is as follows.

[0035] a. Preparation of reaction solutions: Add 100 kg of deionized water to reaction vessel A, turn on the stirring and cooling water, add 105 kg of glycine, stir until completely dissolved, add 40 kg of sodium hydroxide at a rate of 80 kg / h, control the reaction temperature < 95℃, and continue stirring until the reaction is complete to obtain reaction solution A; Add 200 kg of pure water and 225.30 kg of sodium bromoacetate to reaction vessel B, dissolve under stirring to form a microemulsion, add 45 kg of sodium hydroxide at a rate of 60 kg / h, and continue stirring under cooling water until the reaction is complete, controlling the reaction temperature < 85℃ to obtain reaction solution B; Add 200 kg of pure water and 244.90 kg of sodium bromopropionate to reaction vessel C, dissolve under stirring to form a microemulsion, add 45 kg of sodium hydroxide at a rate of 60 kg / h, and continue stirring under cooling water until the reaction is complete, controlling the reaction temperature < 85℃ to obtain reaction solution C.

[0036] b. Two-step substitution synthesis reaction: Open the steam pipeline valve and control the temperature of each reaction solution at 70-80℃ by adjusting the valve size. Use a flow pump to pump reaction solution C into reactor A. To effectively control the pH and temperature of the reaction system, divide reaction solution C into 4-5 portions, pumping at a rate of 98 kg / 5 min, adding one portion every 75-105 min until reaction solution C is completely added, and then maintain the temperature for 12 h. Continue pumping reaction solution B into reactor A, dividing reaction solution B into 3-4 portions, pumping at a rate of 94 kg / 5 min, adding one portion every 75-105 min until reaction solution B is completely added, and then maintain the temperature for 18 h. Filter the obtained reaction solution and measure... The MGDA content (based on solids) was 48.32% w / w. The filtered reaction solution was evaporated and concentrated under a nitrogen atmosphere at 110-120℃ to remove some water, bringing the water content to 40-45% w / w. Then, the temperature was lowered to 20-25℃ and allowed to stand for 12 hours to promote the precipitation of impurities such as sodium bromide. The MGDA solution was obtained by centrifugation, and its bromide content (detection method: automatic potentiometric titration of bromide ion electrode, calculated as bromine, the same below) was 175 mg / kg, and its chloride content (detection method: automatic potentiometric titration of chloride ion electrode, calculated as chlorine, the same below) was 32 mg / kg. During the evaporation process, the nitrogen containing water vapor was recovered, water vapor was removed, and the solution was recycled.

[0037] c. MGDA paste: The MGDA solution obtained in step b is concentrated by triple-effect evaporation at 110~120℃, 120~130℃ and 130~140℃ under a nitrogen atmosphere to remove water to a content of 20~30% w / w, thus obtaining MGDA paste.

[0038] d. MGDA granules: Add ammonium formate, a melting point regulator, to the MGDA paste at a rate of 1.5% of the mass of the MGDA solid (i.e., the solid obtained by drying the MGDA paste); add industrial vitamin C, a heat and oxygen stabilizer, at a rate of 0.3% of the mass of the MGDA solid; add all additives in the form of a saturated solution to keep the material in a molten state with a low melting point. Then, under the condition of maintaining the temperature, transfer the material to the input pipe of the high-tower granulator, with an inlet air temperature of 125~130℃. Under granulation conditions with an oxygen content <2.0% and an airflow rate determined according to particle requirements, moisture removal and granulation are completed. During the particle cooling stage, a hardness modifier, inorganic water-soluble sodium silicate (prepared as a 20-25% concentration solution for spraying), is sprayed onto the surface of the particles. The amount of inorganic water-soluble sodium silicate sprayed (i.e., the amount of inorganic water-soluble sodium silicate in the spraying solution) is 4.5‰ of the solid mass of MGDA. The particle size after spraying is controlled to be 20μm~2mm, and the particle strength is controlled to be 5~20N / mm. 2 MGDA particles are obtained, and particles of the desired particle size and hardness are obtained by sieving. This is the green chelating agent MGDA product I of this embodiment. Materials of non-desirable particle size need to be recycled to the granulation system for secondary processing.

[0039] Using the MGDA particles obtained by the above process as samples, infrared spectra and DSC melting point spectra were measured.

[0040] Figure 1 The DSC melting point spectrum of the MGDA particle sample in Example 1 shows two melting point response values: 115.64℃ is the response value after modification with trisodium methylglycine diacetate, and 186.21℃ is the response value of the byproduct sodium hydroxypropionate; this proves that the sample possesses the product characteristics of MGDA.

[0041] Figure 2 The infrared spectrum of the MGDA particle sample from Example 1 shows multiple absorption peaks, with the most prominent peaks in the characteristic region of 3600–1350 cm⁻¹. -1 Four distinct absorptions were observed, at 3419.36 cm⁻¹. -1 The absorption of OH groups and the absorption of NH4+ were observed at 1587.47 cm⁻¹. -1 Absorption at the C=O group, 1408.38 cm⁻¹ -1 and 1369.62cm -1 The absorption of CH groups and COO- groups at the fingerprint region is consistent with the basic characteristics of amino polycarboxylic acid chelating agents; while the fingerprint region is 1350~400cm. -1 It exhibits a series of absorption peaks, including those from 1019.07 to 1133.42 cm⁻¹. -1Multiple consecutive absorption peaks (5 absorption peaks) indicate CH absorption at different spatial structures, demonstrating the improved chelating performance after modification with trisodium methylglycine diacetate. The richer spatial structure helps reduce the energy required for chelation, thus facilitating the chelation of metal ions. Furthermore, this region also exhibits an 895.92 cm⁻¹ peak. -1 =CH absorption, 721.09cm -1 CH absorption at 559.06 cm⁻¹ -1 The OH bending vibration or CN single bond stretching vibration of the carboxyl group (-COOH) and 410.10 cm⁻¹ -1 Four significant absorption peaks were observed, representing either the out-of-plane bending vibration of the OH group at the carboxyl group or the bending vibration of the molecular skeleton (CC / NC), thus forming the distinctive absorption characteristic of trisodium methylglycine diacetate. Additionally, the absorption peaks of sodium hydroxypropionate were also observed in the infrared spectrum, indicating that the production process involves the secondary substitution of glycine with sodium hydroxypropionate and sodium hydroxyacetate to obtain sodium methylglycine diacetate. Example 2

[0042] A green chelating agent, MGDA product II, is composed of MGDA particles, and the specific production process is as follows.

[0043] a. Preparation of reaction solutions: Add 100 kg of deionized water to reaction vessel A, turn on the stirring and cooling water, add 105 kg of glycine, stir until completely dissolved, add 40 kg of sodium hydroxide at a rate of 80 kg / h, control the reaction temperature < 95℃, and continue stirring until the reaction is complete to obtain reaction solution A; Add 200 kg of pure water and 236.34 kg of sodium bromoacetate to reaction vessel B, dissolve under stirring to form a microemulsion, add 45 kg of sodium hydroxide at a rate of 60 kg / h, and continue stirring under cooling water until the reaction is complete, controlling the reaction temperature < 85℃ to obtain reaction solution B; Add 200 kg of pure water and 256.95 kg of sodium bromopropionate to reaction vessel C, dissolve under stirring to form a microemulsion, add 45 kg of sodium hydroxide at a rate of 60 kg / h, and continue stirring under cooling water until the reaction is complete, controlling the reaction temperature < 85℃ to obtain reaction solution C.

[0044] b. Two-step substitution synthesis reaction: Open the steam pipeline valve and control the temperature of each reaction solution at 70-80℃ by adjusting the valve size. Use a flow pump to pump reaction solution C into reactor A. To effectively control the pH and temperature of the reaction system, divide reaction solution C into 4-5 portions, pumping at a rate of 98 kg / 5 min, adding one portion every 75-105 min until reaction solution C is completely added. Then, maintain the temperature for 11 hours. Continue pumping reaction solution B into reactor A, dividing reaction solution B into 3-4 portions, pumping at a rate of 94 kg / 5 min, adding one portion every 75-105 min until reaction solution B is completely added. After full incorporation, the reaction was kept at a constant temperature for 21 hours. The filtered reaction solution was found to have an MGDA content (based on solids) of 48.74% w / w. The filtered reaction solution was then evaporated and concentrated under a nitrogen atmosphere at 110-120°C to remove some water, bringing the water content to 40-45% w / w. The solution was then cooled to 20-25°C and allowed to stand for 10 hours to promote the precipitation of impurities such as sodium bromide. The MGDA solution was obtained by centrifugation, and its bromide content (based on bromine) was measured to be 183 mg / kg, and its chloride content (based on chlorine) was 35 mg / kg. During the evaporation process, the nitrogen containing water vapor was recovered, the water vapor was removed, and the solution was recycled.

[0045] c. MGDA paste: The MGDA solution obtained in step b is concentrated by triple-effect evaporation at 110~120℃, 120~130℃ and 130~140℃ under a nitrogen atmosphere to remove water to a content of 20~30% w / w, thus obtaining MGDA paste.

[0046] d. MGDA Granules: Add potassium hydroxide, a melting point regulator, to the MGDA paste at a rate of 1.0% of the MGDA solid mass; add a mixture of industrial vitamin C and glucose at a mass ratio of 2:1, a mixture at a rate of 0.2% of the MGDA solid mass; add all additives in the form of a saturated solution to keep the material in a molten state with a low melting point. Then, under the condition of maintaining the temperature, transfer the material to the input pipe of the high-tower granulator. Granulation is completed under granulation conditions of inlet air temperature of 125~130℃, oxygen content <2.0%, and inlet air flow rate determined according to particle requirements. During the particle cooling stage, spray water-dispersible silica, a hardness regulator (prepared as a solution with a concentration in the range of 20~25%), onto the surface of the particles. The amount of water-dispersible silica sprayed is 3.0‰ of the MGDA solid mass. Control the particle size after spraying to be 20μm~2mm and the particle strength to be 5~20N / mm. 2 MGDA particles are obtained, and particles with the required particle size and hardness are obtained by sieving. This is the green chelating agent MGDA product II of this embodiment. Materials with non-required particle size need to be recycled to the granulation system for secondary processing. Example 3

[0047] A green chelating agent, MGDA product III, is composed of MGDA particles, and its specific production process is as follows: a. Preparation of reaction solutions: Add 100 kg of deionized water to reaction vessel A, turn on the stirring and cooling water, add 105 kg of glycine, stir until completely dissolved, add 40 kg of sodium hydroxide at a rate of 80 kg / h, control the reaction temperature < 95℃, and continue stirring until the reaction is complete to obtain reaction solution A; Add 200 kg of pure water and 223.50 kg of sodium bromoacetate to reaction vessel B, dissolve under stirring to form a microemulsion, add 45 kg of sodium hydroxide at a rate of 60 kg / h, and continue stirring under cooling water until the reaction is complete to obtain reaction solution B; Add 200 kg of pure water and 250.20 kg of sodium bromopropionate to reaction vessel C, dissolve under stirring to form a microemulsion, add 45 kg of sodium hydroxide at a rate of 60 kg / h, and continue stirring under cooling water until the reaction is complete to obtain reaction solution C.

[0048] b. Two-step substitution synthesis reaction: Open the steam pipeline valve and control the temperature of each reaction solution at 70-80℃ by adjusting the valve size. Use a flow pump to pump reaction solution C into reactor A. To effectively control the pH and temperature of the reaction system, divide reaction solution C into 4-5 portions, pumping at a rate of 98 kg / 5 min, adding one portion every 75-105 min until reaction solution C is completely added. Then, maintain the temperature for 13 hours. Continue pumping reaction solution B into reactor A, dividing reaction solution B into 3-4 portions, pumping at a rate of 94 kg / 5 min, adding one portion every 75-105 min until reaction solution B is completely added. After full incorporation, the reaction was kept at a constant temperature for 15 hours. The filtered reaction solution was found to have an MGDA content (based on solids) of 48.27% w / w. The filtered reaction solution was then evaporated and concentrated under a nitrogen atmosphere at 110-120°C to remove some water, bringing the water content to 40-45% w / w. The solution was then cooled to 20-25°C and allowed to stand for 12 hours to promote the precipitation of impurities such as sodium bromide. The MGDA solution was obtained by centrifugation, and its bromide content (based on bromine) was measured to be 168 mg / kg, and its chloride content (based on chlorine) was 41 mg / kg. During the evaporation process, the nitrogen containing water vapor was recovered, dehydrated, and recycled.

[0049] c. MGDA paste: The MGDA solution obtained in step b is concentrated by triple-effect evaporation at 110~120℃, 120~130℃ and 130~140℃ under a nitrogen atmosphere to remove water to a content of 20~30% w / w, thus obtaining MGDA paste.

[0050] d. MGDA Granules: Add potassium hydroxide, a melting point regulator, to the MGDA paste at a rate of 1.5% of the MGDA solid mass; add industrial vitamin C, a heat and oxygen stabilizer, at a rate of 0.3% of the MGDA solid mass. All additives are added in saturated solution form to maintain the material in a molten state with a low melting point. Then, under temperature-controlled conditions, transfer the material to the input pipe of a high-tower granulator. Granulation is completed under conditions of an inlet air temperature of 125-130℃, an oxygen content of <2.0%, and an inlet air flow rate determined according to particle requirements. During the particle cooling stage, spray a hardness regulator, inorganic water-soluble sodium silicate (prepared as a 20-25% concentration solution), onto the surface of the granules. The amount of inorganic water-soluble sodium silicate sprayed is 6.0‰ of the MGDA solid mass. Control the particle size after spraying to be 20μm-2mm and the particle strength to be 5-20N / mm. 2 MGDA particles are obtained, and particles with the required particle size and hardness are obtained by sieving. This is the green chelating agent MGDA product III of this embodiment. Materials with non-required particle size need to be recycled to the granulation system for secondary processing. Example 4

[0051] A green chelating agent, MGDA product IV, is composed of a mixture of MGDA particles and potassium iminodisuccinate, with a mass ratio of 5:1. The production process and conditions of the MGDA particles are the same as in Example 1. The potassium iminodisuccinate is a commercially available product, thus obtaining the green chelating agent MGDA product IV of this embodiment. Example 5

[0052] A green chelating agent MGDA product V is composed of MGDA particles, tetrasodium glutamate diacetate (GLDA), and ethylenediamine disuccinic acid (EDDS) in a mass ratio of 10:1:1. The production process and conditions of MGDA particles are the same as those in Example 1. GLDA and EDDS are commercially available products, thus obtaining the green chelating agent MGDA product V of this embodiment.

[0053] Comparative Example 1 Commercially available MGDA products are produced using a hydrogen cyanide process.

[0054] The infrared spectrum and DSC melting point spectrum of the MGDA sample from Comparative Example 1 were measured.

[0055] Figure 3 The DSC melting point spectrum of the MGDA sample in Comparative Example 1 shows two melting point response values: 140.54℃ is the response value of unmodified trisodium methylglycine diacetate, and 205.90℃ is the response value of the byproduct NTA (nitrotriacetic acid); it exhibits the product characteristics of mainstream hydrogen cyanide production schemes.

[0056] Figure 4 The infrared spectrum of the MGDA sample in Comparative Example 1 shows multiple absorption peaks; among them, the characteristic region is 3600~1350 cm⁻¹. -1 Four distinct absorbances were observed, at 3423.75 cm⁻¹. -1 The absorption of OH groups and the absorption of NH4+ were observed at 1586.87 cm⁻¹. -1 Absorption at the C=O group, 1408.68 cm⁻¹ -1 and 1369.78cm -1 The absorption of CH groups and COO- groups at the fingerprint region conforms to the basic characteristics of amino polycarboxylic acid chelating agents, the same as in Example 1; while the fingerprint region is 1350~400cm -1 It exhibits a series of absorption peaks, including 1018.45~1132.79 cm⁻¹. -1 Multiple consecutive absorption peaks (4 absorption peaks) indicate CH absorption with different spatial structures. Compared with Example 1, the difference in spatial structure richness is significant, and the absorption response value is significantly weaker, indicating that the chelating activity is significantly lower than that of Example 1. In addition, there is a 556.28 cm⁻¹ peak in this region. -1 A significant absorption peak is observed due to the OH bending vibration or CN single bond stretching vibration of the carboxyl group (-COOH), forming a significant absorption characteristic of trisodium methylglycine diacetate. However, this may also be due to the overlap of absorption peaks caused by the high similarity between MGDA and NTA, which is consistent with the structural characteristics of MGDA produced by the hydrogen cyanide process.

[0057] Comparative Example 2 The MGDA solution synthesized in Example 1 (step b) was directly granulated by high-tower spraying after the addition of industrial vitamin C, an anti-thermal and oxygen stabilizer, to obtain MGDA particles. Compared with Example 1, the only difference is that the triple-effect evaporation and concentration were not carried out in the granulation process, and no melting point regulator was added. All other preparation conditions were the same as in Example 1.

[0058] Application Example - Chelation Value Method The chelating ability of the chelating agent MGDA in the above examples and comparative examples was tested according to GB / T21884-2008 Standard for Determination of Chelating Ability of Textile Printing and Dyeing Auxiliaries. The test results are shown in Table 1 below.

[0059] Table 1. Chelation capacity of each embodiment and comparative example

[0060] As can be seen from the data in the table above, the chelating ability of the MGDA chelating agent product of this invention is significantly improved compared with the MGDA product produced by the traditional hydrogen cyanide process. Furthermore, the concentration and drying granulation process of this invention has a significant protective effect on chelating activity compared with the traditional granulation process. The morphological characteristics of the MGDA particles synthesized by this invention are as follows: Figure 5As shown.

[0061] The synthesis process of this invention can yield qualified MGDA products. However, the granulation process also significantly affects the activity of the granulated products (measured by calcium chelation value). In particular, the high temperature and oxygen involved in the concentration and granulation processes, and the oxidative decomposition caused by both, can damage the molecular structure of MGDA and reduce its chelating activity. Furthermore, the MGDA product of this invention can be used in combination with other aminopolycarboxylic acid green chelating agents, which helps to increase the overall chelating performance and significantly improves the iron chelation value.

[0062] In summary, the green chelating agent MGDA product of this invention, through a modified synthesis process, synthesizes MGDA from glycine via a two-step substitution method involving sodium bromopropionate and sodium bromoacetate. Further processing, including low-temperature concentration under an inert atmosphere, impurity removal, multi-effect evaporation concentration, and granulation, not only achieves high chelating activity and product quality but also eliminates environmental risks associated with the production process. This enables the provision of various high-end MGDA series products for the detergent, daily chemical, and hygiene industries, promoting the application of the green chelating agent MGDA in high-end daily necessities.

[0063] Please note that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A green chelating agent MGDA product, characterized in that: It contains MGDA solution, MGDA paste, or MGDA particles synthesized by a two-step substitution method of glycine via sodium bromopropionate and sodium bromoacetate. The synthesis of MGDA involves preparing glycine into a sodium glycinate solution, which is then subjected to a substitution reaction with sodium bromopropionate solution and sodium bromoacetate solution. The resulting reaction solution is evaporated and concentrated at 110-120℃ under an inert gas atmosphere to reduce the water content to 40-45% w / w. The solution is then cooled to remove impurities and obtain the MGDA solution. And / or, the MGDA solution is further concentrated into a paste under an inert gas atmosphere; and / or, after adding an additive to the MGDA paste, water removal and granulation are carried out to obtain MGDA particles.

2. The green chelating agent MGDA product according to claim 1, characterized in that: The sodium glycinate solution is obtained by reacting a solution obtained by completely dissolving glycine with sodium hydroxide at a reaction temperature <95℃; and / or, the sodium bromopropionate solution is obtained by reacting a microemulsion obtained by dissolving sodium bromopropionate with sodium hydroxide at a reaction temperature <85℃; and / or, the sodium bromoacetate solution is obtained by reacting a microemulsion obtained by dissolving sodium bromoacetate with sodium hydroxide at a reaction temperature <85℃.

3. The green chelating agent MGDA product according to claim 1, characterized in that: The substitution synthesis reaction of sodium glycinate solution and sodium bromopropionate solution is carried out at a temperature of 70~80℃, and the molar ratio of sodium bromopropionate to glycine is 1~1.1:1; the substitution synthesis reaction of sodium bromoacetate solution and sodium bromoacetate solution is carried out at a temperature of 70~80℃, and the molar ratio of sodium bromopropionate to glycine is 1~1.1:

1.

4. The green chelating agent MGDA product according to claim 1, characterized in that: The MGDA solution was concentrated by triple-effect evaporation at 110~120℃, 120~130℃ and 130~140℃ in sequence to obtain an MGDA paste with a water content of 20~30%.

5. The green chelating agent MGDA product according to claim 1, characterized in that: Adding additives to MGDA paste, followed by thorough emulsification, moisture removal and granulation, and then spraying a hardness modifier onto the surface of the granules, yields MGDA granule products.

6. The green chelating agent MGDA product according to claim 5, characterized in that: The additives include melting point regulators and heat-oxidation stabilizers. Preferably, the melting point regulator is added at 1.0-2.5% of the mass of MGDA, and the melting point regulator is selected from substances with a melting point below 140°C, more preferably potassium hydroxide, alkanolamines, or ammonium formate. The heat-oxidation stabilizer is added at 0.2-0.4% of the mass of MGDA, and the heat-oxidation stabilizer is selected from industrial vitamin C or a mixture of industrial vitamin C and glucose, with a mass ratio of industrial vitamin C to glucose of 1-3:

1. The hardness regulator is added at 3-6‰ of the mass of MGDA, and is selected from inorganic water-soluble silicates or water-dispersible silica.

7. The green chelating agent MGDA product according to claim 1, characterized in that: The green chelating agent MGDA product contains no more than 300 mg / kg of bromide (calculated as bromine) and no more than 100 mg / kg of chloride (calculated as chlorine), and does not contain the prohibited substance NTA; and / or, The green chelating agent MGDA product also includes aminopolycarboxylic acid green chelating agents other than MGDA. Preferably, the mass content of the aminopolycarboxylic acid green chelating agent other than MGDA does not exceed 20% of the mass content of MGDA. More preferably, the aminopolycarboxylic acid green chelating agent other than MGDA is selected from at least one of tetrasodium iminodisuccinate, tetrasodium glutamate diacetate, tetrasodium aspartate diacetate, and ethylenediaminedisuccinate.

8. A synthesis process for MGDA, characterized in that, The synthesis steps include the following: a. Preparation of reaction solutions: Deionized water is added to reaction vessel A. Under stirring and cooling conditions, glycine is added and completely dissolved. Sodium hydroxide is then added, and the reaction temperature is controlled to be <95℃. After the reaction is complete, reaction solution A is obtained. Deionized water and sodium bromoacetate are added to reaction vessel B. Under stirring and cooling conditions, the mixture is dissolved into a microemulsion. Sodium hydroxide is then added, and the reaction temperature is controlled to be <85℃. After the reaction is complete, reaction solution B is obtained. Deionized water and sodium bromopropionate are added to reaction vessel C. Under stirring and cooling conditions, the mixture is dissolved into a microemulsion. Sodium hydroxide is then added, and the reaction temperature is controlled to be <85℃. After the reaction is complete, reaction solution C is obtained. Preferably, the concentration of the solution prepared by glycine and deionized water is 51±1% w / w, and the molar ratio of sodium hydroxide to glycine is 1:1.3~1.

5. Preferably, the concentration of the microemulsion prepared by sodium bromoacetate or sodium bromopropionate and deionized water is 52-65% w / w, and the molar ratio of sodium hydroxide to sodium bromoacetate or sodium bromopropionate is 1:1.1-1.

4. b. Two-step substitution synthesis reaction: Heat each reaction solution to 70~80℃, pump reaction solution C into reaction vessel A, and keep the reaction temperature for 11~13h after complete addition; continue to pump reaction solution B into reaction vessel A, and keep the reaction temperature for 15~21h after complete addition. The filtered reaction solution is concentrated by evaporation at 110~120℃ under an inert gas atmosphere. After controlling the water content to reach 40~45%w / w, the temperature is lowered to 20~25℃, and then allowed to stand for 10~12h to promote the precipitation of impurities. Solid-liquid separation is performed to obtain MGDA solution.

9. The synthesis process of MGDA according to claim 8, characterized in that, The MGDA solution was further concentrated and dehydrated to obtain an MGDA paste; the concentration and dehydration process was as follows: The MGDA solution was concentrated under a nitrogen atmosphere by triple-effect evaporation at 110-120°C, 120-130°C and 130-140°C to obtain an MGDA paste with a water content of 20-30% w / w.

10. A granulation process for MGDA, characterized in that, Based on the synthesis steps of claim 9, a modification and granulation step is added to obtain MGDA particles; the modification and granulation steps are operated as follows: A saturated solution of melting point regulator and heat-oxidation stabilizer is added sequentially to the MGDA paste. Then, the paste is mixed at medium and high speed and degassed by ultrasonication to obtain a fully emulsified paste. The paste is then granulated by removing moisture and passing it through a high-tower granulator. During the cooling stage, a hardness regulator is sprayed onto the surface of the granules to control the particle size of the granules after spraying to be between 20μm and 2mm, thus obtaining MGDA granules. Preferably, the medium-to-high speed mixing rate is not less than 1500 r / min, and / or the hardness modifier is applied using a directional, continuous spraying method, with a coating coverage of not less than 80% on the particle surface, and the obtained MGDA particle strength is 5~20 N / mm. 2 .

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