Stable methylglycine-n,n-diacetic acid trialkali metal salt compositions, processes for their preparation and use

Abstract

The application discloses a storage-stable methylglycine-N,N-diacetic acid trialkali salt composition and a preparation method and application thereof, which comprises methylglycine-N,N-diacetic acid trialkali salt, N,N-dimethylglycine metal salt, sulfite and water. The composition can be used for storing and / or stabilizing transportation of methylglycine-N,N-diacetic acid trialkali salt, improving the stability of the metal ion chelating ability of the composition product, especially the stability of the chelating ability of calcium ions and magnesium ions, and the composition product can be stably applied to the fields of daily washing, water softening and sewage treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic chemical industry, in particular to a storage-stable alkali metal salt composition of methyl glycine-N, N-diacetic acid and a preparation method and application thereof. BACKGROUND

[0002] Methyl glycine-N, N-diacetic acid, abbreviated as MGDA, can form a 1:1 ligand compound with common metal ions, has a wide applicable pH range (2-13.5), and has the characteristics of strong chelating ability and high efficiency, superior toxicological safety and biological biodegradability. Currently, the industrialized commercial products are mainly solutions or solid products of methyl glycine diacetic acid trisodium salt (MGDA·3Na).

[0003] In the prior art, MGDA·3Na is usually synthesized by Strecker reaction, and the synthesis route thereof is divided into two categories. The first category is to perform Strecker reaction on propionitrile or alanine with cyanide and formaldehyde, and then hydrolyze to obtain the product. The reactant propionitrile or DL-alanine can be prepared by reacting hydrocyanic acid, ammonia water and acetaldehyde. D-alanine and L-alanine, DL-alanine can also be obtained by biological fermentation method and enzyme method. The second category is to perform Strecker reaction on imino diethyl cyanide or imino diacetic acid with cyanide and acetaldehyde, and then hydrolyze to obtain the product. The reactant imino diethyl cyanide or imino diacetic acid can be prepared by hydrocyanic acid, ammonia water and formaldehyde. In addition, there is another industrial process which uses chloroacetic acid as a raw material for synthesis, and there are related patents and market products. However, the indexes and qualities of the products of the MGDA aqueous solution prepared by different processes have obvious differences, and the product stability and downstream application fields also have differences.

[0004] Washing water contains various metal ions to varying degrees. In order to eliminate the influence, it is often necessary to add a chelating (complexing) agent to form a stable, water-soluble complex with hardness ions or high-valent metal ions in water by complexation, and to remain in the aqueous solution. As known technical information, an important parameter for evaluating the ability of a chelating agent is the stability constant K of the complex formed by the chelating agent and the corresponding metal ion.

[0005]

[0006] MeZ (m-m)- represents the concentration of the chelate

[0007] Me n+ represents the concentration of free, positively charged metal ions

[0008] Z m- represents the concentration of the chelating agent

[0009] K represents the stability constant of the chelating agent

[0010] The metal chelating capacity of MGDA alkali metal solution products prepared by different technical routes and production process parameters has certain differences. CN111100023A, CN110903206A, and CN110938010A disclose the preparation of different MGDA metal chelates and the determination of the stability constant of the MGDA metal chelate. Most patents mainly focus on the synthesis process parameters of MGDA, intermediate optimization, product yield improvement, product color number improvement, and harmful impurity control optimization (NTA, formaldehyde, other amino acids, etc.). For example, US5817864, US5849950, CN101171226B, CN103476741B, US8802894, CN102993034B, CN106928077B, and CN115710194A related patents. Patents for preparing MGDA by chloroacetic acid method focus on the synthesis process, catalyst, and some involve metal chelating capacity data, such as CN107118114B, CN109134286A, CN109912440A, CN109369428A, CN112898169A, and CN114163340A. However, none of them can explain the test interference and differences of the chelating capacity of the product, nor can they tell the storage period and stability of the product, whether the chelating capacity of the product can be kept stable for a long period.

[0011] From the current public information, the COA of the MGDA·3Na aqueous solution product sold on the market shows that the shelf life of the MGDA product is 8-12 months. Industry data and technical information show that the shelf life of the product is 2 years or 3 years. Therefore, the stability research and the improvement and maintenance of the metal chelating capacity of the MGDA alkali metal solution product are still one of the optimization directions, and the difference characteristics of the MGDA product for different synthesis technology sources and application fields need to be reflected. SUMMARY

[0012] Therefore, the purpose of the present application is to provide a storage-stable methyl glycine-N,N-diacetic acid trialkali metal salt composition and a preparation method, which comprises methyl glycine-N,N-diacetic acid trialkali metal salt, N,N-dimethyl glycine metal salt, sulfite, water and other specific components. The composition can achieve stable storage for a relatively long period of time (up to 48 months).

[0013] The purpose of the present application is also to provide the use of the above-mentioned composition for stable storage and / or transportation of methyl glycine-N,N-diacetic acid trialkali metal salt, and to improve the stability of the metal ion chelating capacity of the composition product, especially to improve the stability of the chelating capacity of calcium ions and magnesium ions.

[0014] Another object of the present application is to provide the use of the composition in the field of daily washing, water softening and sewage treatment.

[0015] To achieve the above objects, the present application adopts the following technical solutions:

[0016] In a first aspect, the present application provides a storage-stable tris-alkali metal methyl glycine-N,N-diacetic acid (MGDA tris-alkali metal salt) composition comprising the following components in mass percentage:

[0017] 18.0-45.0 wt%, for example 18.0 wt%, 20.0 wt%, 25.0 wt%, 30.0 wt%, 35.0 wt%, 40.0 wt%, 45.0 wt%, preferably 25.0-40.0 wt% of methyl glycine-N,N-diacetic acid tris-alkali metal salt;

[0018] 0.1-1.0 wt%, for example 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt% of N,N-dialkyl glycine alkali metal salt;

[0019] 0.1-1.0 wt%, for example 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt% of sulfite;

[0020] and 53.0-81.8 wt%, for example 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, preferably 58.0-75.0 wt% of water;

[0021] The sum of the contents of each component is 100 wt%.

[0022] In the present application, the methyl glycine-N,N-diacetic acid tris-alkali metal salt of component (A) is at least one of methyl glycine-N,N-diacetic acid trisodium salt (MGDA·3Na) and methyl glycine-N,N-diacetic acid tripotassium salt (MGDA·3K);

[0023] Preferably, the methyl glycine-N,N-diacetic acid tris-alkali metal salt of component (A) can be in the form of an aqueous solution with a concentration of 18.0-45.0 wt%, for example 18.0 wt%, 20.0 wt%, 25.0 wt%, 30.0 wt%, 35.0 wt%, 40.0 wt%, 45.0 wt%.

[0024] The methyl glycine-N, N-diacetic acid (MGDA) trialkali metal salt of component (A) is a product disclosed in the prior art, and the source thereof is not particularly required in the present application. It can be directly purchased or prepared by using the prior art method. For example, it can be derived from the Strecker reaction of hydrocyanic acid process or from the MGDA prepared by the chloroacetic acid method. The above-mentioned methods are all known in the prior art, such as the methods disclosed in patents US5849950, US8802894, CN101171226B, CN103476741B and CN107118114B. The main influencing factor for limiting the raw material concentration of the methyl glycine-N, N-diacetic acid trialkali metal salt of component (A) is the synthesis raw material alpha-alanine. The solubility of single alpha-alanine is low (mass concentration < 18%), and the pH value of the solution after dissolution is about 6. In order to reduce the production cost and transportation cost and improve the reaction rate, it is expected to prepare a high-concentration concentrated MGDA product. From the prior art and product properties, a 40% mass content MGDA·3Na solution prepared by DL-alanine can be stored at room temperature, but in a local or temporary cold environment, impurities in the solution can cause MGDA to precipitate, form crust in pipelines and containers, or generate impurities or non-uniformity during downstream use, which affects the product quality indicators, such as the decrease of main content and metal chelating capacity, and other negative effects. The present inventors have unexpectedly found that the methyl glycine-N, N-diacetic acid trialkali metal salt, together with a certain amount of N, N-dialkyl glycine alkali metal salt, sulfite and water, can effectively solve the above-mentioned problems.

[0025] In one preferred embodiment, the raw material of the methyl glycine-N, N-diacetic acid trialkali metal salt of component (A) can be a commercially available product, and is selected from at least one of commercially available 30wt% MGDA·3Na aqueous solution and 40wt% MGDA·3Na aqueous solution; preferably, the preparation method thereof is the chloroacetic acid method or the Strecker method of hydrocyanic acid.

[0026] In another preferred embodiment, the raw material of the methyl glycine-N, N-diacetic acid trialkali metal salt of component (A) can be obtained by self-preparation, and is preferably an 18.0-45.0wt% aqueous solution prepared by the chloroacetic acid method or the Strecker method of hydrocyanic acid; preferably, the concentration of the aqueous solution can be controlled in any required concentration range by process parameters and concentration or dilution, and the overall economy is more optimal.

[0027] In a preferred embodiment of the present application, the aqueous solution of the trialkali metal salt of methyl glycine-N,N-diacetic acid as the raw material of component (A) of the trialkali metal salt of methyl glycine-N,N-diacetic acid (MGDA trialkali metal salt) composition should meet the following requirements: the content of nitrilotriacetic acid salt is 0.0-0.1 wt%, the content of formaldehyde and formaldehyde releasing bodies is 0-50 ppm, the content of chlorine is 0.001-3.0 wt%, and the Hazen color number is 30-330, based on the total mass of the aqueous solution.

[0028] In the present application, the alkali metal salt of N,N-dialkyl glycine of component (B) is at least one selected from the group consisting of sodium N,N-dimethyl glycinate, sodium N,N-diethyl glycinate, sodium N,N-dipropyl glycinate, potassium N,N-dimethyl glycinate, potassium N,N-diethyl glycinate, and potassium N,N-dipropyl glycinate, and is preferably sodium N,N-dimethyl glycinate and / or potassium N,N-dimethyl glycinate.

[0029] As a preferred embodiment, the alkali metal salt of N,N-dialkyl glycine of component (B) can be directly purchased or prepared by existing methods, and can be directly added as a solid raw material or prepared as an aqueous solution by mixing N,N-dimethyl glycine with an alkali metal hydroxide (such as sodium hydroxide or potassium hydroxide), wherein the purity of N,N-dimethyl glycine and the alkali metal hydroxide is required to be greater than 99.0 wt% to avoid the influence of other potential impurities on the indicators of the composition.

[0030] In the present application, the sulfite of component (C) is at least one selected from the group consisting of sodium sulfite, potassium sulfite, sodium bisulfite, and potassium bisulfite.

[0031] In the present application, the water includes the water introduced by the raw materials of components (A)-(C), and specifically, can be the water introduced by the raw materials of components (A)-(C) or the raw material water directly added.

[0032] In a second aspect, the present application provides a preparation method of the storage-stable trialkali metal salt of methyl glycine-N,N-diacetic acid (MGDA trialkali metal salt) composition, which adopts a conventional physical mixing method in the field.

[0033] Specifically, the preparation method of the storage-stable trialkali metal salt of methyl glycine-N,N-diacetic acid (MGDA trialkali metal salt) composition comprises the following steps: weighing the trialkali metal salt of methyl glycine-N,N-diacetic acid, the alkali metal salt of N,N-dialkyl glycine, the sulfite, and water according to the proportions, and mixing them uniformly to obtain the composition.

[0034] In the present application, the N,N-dialkyl glycine alkali metal salt of component (B) and the sulfite of component (C) can be in the form of solid or aqueous solution, and are fully mixed with the methyl glycine-N,N-diacetic acid trialkali metal salt of component (A) to prepare a methyl glycine-N,N-diacetic acid trialkali metal salt composition.

[0035] The prepared composition is stored under the product storage conditions of MGDA·3Na or MGDA·3K, sealed in a low-temperature and light-proof manner, and the material quality is required, and there is no difference in other non-differentiated special requirements.

[0036] In a third aspect, the present application provides the use of the above-mentioned composition for stably storing and / or transporting the methyl glycine-N,N-diacetic acid trialkali metal salt, and improving the stability of the metal ion chelating ability of the composition product, in particular, improving the stability of the calcium ion and magnesium ion chelating ability.

[0037] The present application combines the methyl glycine-N,N-diacetic acid trialkali metal salt with the N,N-dimethyl glycine metal salt, the sulfite and water, which can significantly improve the stability of the composition, and when the composition is used for storing and / or stably transporting the methyl glycine-N,N-diacetic acid trialkali metal salt, it can be stored and / or stably transported for at least 24 months, for example, 24 months, 26 months, 30 months, 35 months, 40 months, 45 months, 48 months, 50 months, and preferably up to 48 months or more at a temperature of 0℃ to 40℃, preferably 5℃ to 25℃.

[0038] The present application combines the methyl glycine-N,N-diacetic acid trialkali metal salt with the N,N-dimethyl glycine metal salt, the sulfite and water, which can significantly improve the stability of the composition, and when the composition is used for storing and / or stably transporting the methyl glycine-N,N-diacetic acid trialkali metal salt, it can be stored and / or stably transported for at least 24 months, for example, 24 months, 26 months, 30 months, 35 months, 40 months, 45 months, 48 months, 50 months, and preferably up to 48 months or more at a temperature of 0℃ to 40℃, preferably 5℃ to 25℃.

[0039] In a fourth aspect, the present application provides the use of the composition in the fields of daily washing, water softening and sewage treatment.

[0040] Compared with the prior art, the present application has the following beneficial effects:

[0041] 1) The methyl glycine-N,N-diacetic acid tris alkali metal salt composition of the present application has high storage stability, and the aqueous solution of the composition has a storage period of at least 24 months, up to 48 months or more, which is better than the product stability period reported in some prior art, and the product index change is also within the control range.

[0042] 2) The composition of the present application can improve the stability of the chelating ability of metal ions in the composition product, especially the chelating ability of calcium ions and magnesium ions, and has no obvious interference in the downstream application field.

[0043] 3) The composition product of the present application has simple preparation process operation, stable process, high product quality, good performance, and good market economic benefits, and can be stably applied in the fields of daily washing, water softening and sewage treatment, etc., without obvious differentiation restriction. DETAILED DESCRIPTION

[0044] The following examples will further illustrate the method provided by the present application, but the present application is not limited to the listed examples, and any other known changes within the scope of the claims of the present application should also be included.

[0045] In addition to the conventional analysis method known to the industry, the composition components and product indexes, chelating ability test and other methods of the present application are described in detail as follows:

[0046] The content detection method of methyl glycine-N,N-diacetic acid tris alkali metal salt (MGDA·3Na / MGDA·3K) is as follows: the industry known ferric chloride complex potential titration method is adopted, and the typical test method is as follows: an automatic potential titrator (metrohm 905 Titrando) is prepared, which is provided with a platinum composite electrode, 0.50-1.0 g of sample is weighed, which is accurate to 0.1 mg, 50 ml of ultrapure water is added, 2 drops of phenolphthalein indicator is added, and the sample system PH value is adjusted to red disappearance by 0.6 mol / L hydrochloric acid (if the sample has interference due to different preparation processes, a glycine buffer solution with PH=2.8 or a chloroacetic acid-sodium acetate buffer solution with PH=3 can be added to adjust the system PH value), and the 0.1 mol / L ferric chloride standard solution is titrated to the potential jump on the potential titrator.

[0047] N,N-dialkyl glycine alkali metal salt (N,N-dimethyl glycine and its alkali metal salt) content determination: external standard method of high performance liquid chromatography. Chromatographic column Agilent Zorbax SB-C18 150 mm x 4.6 mm, 3.5 μm (or chromatographic column with equivalent effect), mobile phase A (water containing 0.1 mol / L sodium octane sulfonate and 0.1% phosphoric acid): mobile phase B (methanol) = 90:10 (volume ratio), flow rate is 1.0 mL / min, detection wavelength is 210 nm, injection volume is 25 μL, column temperature is 30°C.

[0048] Sulfite content determination: industry-known ion chromatography external standard method quantitative analysis.

[0049] Nitrilotriacetate (NTA·3Na) content: industry-known ion chromatography or liquid chromatography external standard method quantitative analysis.

[0050] Chlorine content: industry-known silver nitrate potentiometric titration method quantitative analysis.

[0051] Hazen color number: GB / T 3143 liquid chemical product color determination method (Hazen unit-palladium-cobalt color number).

[0052] Calcium ion chelating ability determination method: using calcium standard solution complexing potentiometric titration method, typical test method automatic potentiometric titrator (metrohm 905Titrando), provided with platinum composite electrode or calcium ion selective electrode, sample weighing 0.50-1.0 g, accurate to 0.1 mg, adding 50 ml of ultrapure water, 20 ml of ammonia water-ammonium chloride buffer solution, adjusting pH value to 10.5-11, controlling temperature to be 23°C, titrating to potential jump on the potentiometric titrator with 0.1 mol / L calcium acetate or calcium chloride standard solution, and taking calcium ion binding amount (mg Ca 2+ / g of chelating agent, pH=11, 23°C, 0.1M).

[0053] Metal ion (magnesium ion) chelating ability determination method: using magnesium standard solution complexing potentiometric titration method, typical test method automatic potentiometric titrator (metrohm 905Titrando) is prepared, provided with platinum composite electrode, sample weighing 0.50-1.0 g, accurate to 0.1 mg, adding 50 ml of ultrapure water, 20 ml of ammonia water-ammonium chloride buffer solution, adjusting pH value to 10.5-11, controlling temperature to be 23°C, titrating to potential jump on the potentiometric titrator with 0.1 mol / L magnesium chloride standard solution, and taking magnesium ion binding amount (mg Mg 2+ / g of chelating agent, pH=11, 23°C, 0.1M).

[0054] Known literature data MGDA data (Ca 2+Ion: logK = 7.0, 0.1 M, 25°C) and (Mg 2+ Ion: logK = 5.8, 0.1 M, 25°C), MGDA has stronger chelating ability to calcium ion than magnesium ion, the examples and comparative examples mainly take the data of calcium ion chelating ability as the basis and comparison, theoretically, the chelating ability of MGDA.3Na (molecular weight 271.1) to calcium ion is 147.5 (mg Ca 2+ / g per hundred chelating agent), and the chelating ability to magnesium ion is 89.6 (mg Mg 2+ / g per hundred chelating agent).

[0055] The main raw material source information in the examples and comparative examples of the present application is as follows, and other materials not specifically mentioned are obtained from ordinary commercial channels:

[0056] Sodium N,N-dimethylglycinate: Henan Alpha Chemical Co., Ltd., industrial grade product;

[0057] Sodium N,N-dimethylglycinate, sodium N,N-diethylglycinate, sodium N,N-dipropylglycinate, potassium N,N-dimethylglycinate, potassium N,N-diethylglycinate, and potassium N,N-dipropylglycinate: purchased from Beijing Inokai Technology Co., Ltd., Shanghai Aladdin Biochemical Technology Co., Ltd., and Tixi Ai Shanghai Chemical Industry Development Co., Ltd., respectively, analytical grade reagent;

[0058] Sodium sulfite, sodium bisulfite, potassium sulfite, and potassium bisulfite: many suppliers on the market, industrial grade or food grade, main content > 98%, the present application selects Shandong Jinshengrun Chemical Co., Ltd. and Shandong Tengwang Chemical Co., Ltd.

[0059] Example 1

[0060] 1) Preparation of component (A) MGDA.3Na: L-alanine as raw material, Strecker reaction was used to synthesize MGDA.3Na

[0061] To a 1 liter stirred flask preheated to 30°C, 400 g of deionized water was added, then 107.7 g (1.2 mol) of solid L-alanine was added. Over a period of 30 minutes, 50% aqueous sodium hydroxide solution (31.8 g, 0.78 mol) was added to the resulting slurry. After the addition was complete, the slurry was allowed to stir at 30-40°C for 30 minutes to obtain a clear, partially neutralized, alkaline, light yellow solution of alanine with an initial concentration of 20% and a pH of 9.9 (25°C). Simultaneously, 196.8 g (2.44 mol) of 37% commercial formaldehyde solution and 33.4 g (1.23 mol) of 99% HCN were added dropwise over a total period of 1 hour. Then, an additional 33.4 g (1.23 mol) of HCN was added over a period of 0.5 hours at 30-35°C. The reaction mixture was stirred at 35-40°C for 1 hour to obtain a mixture of methylglycine-N,N-diacetonitrile solution 820.5 g.

[0062] To a 1 liter stirred flask preheated to 30°C, 400 g of deionized water was added, then 107.7 g (1.2 mol) of solid L-alanine was added. Over a period of 30 minutes, 50% aqueous sodium hydroxide solution (31.8 g, 0.78 mol) was added to the resulting slurry. After the addition was complete, the slurry was allowed to stir at 30-40°C for 30 minutes to obtain a clear, partially neutralized, alkaline, light yellow solution of alanine with an initial concentration of 20% and a pH of 9.9 (25°C). Simultaneously, 196.8 g (2.44 mol) of 37% commercial formaldehyde solution and 33.4 g (1.23 mol) of 99% HCN were added dropwise over a total period of 1 hour. Then, an additional 33.4 g (1.23 mol) of HCN was added over a period of 0.5 hours at 30-35°C. The reaction mixture was stirred at 35-40°C for 1 hour to obtain a mixture of methylglycine-N,N-diacetonitrile solution 820.5 g.

[0063] 2) Storage-stable MGDA.3Na composition preparation:

[0064] To the 40.47 wt% L-MGDA.3Na aqueous solution 770.9 g prepared in Step 1), solid sodium N,N-dimethylglycinate 4.7 g and solid sodium sulfite 2.4 g were added at room temperature. After stirring and dissolving, a total of 778 g of storage-stable L-MGDA.3Na composition was obtained.

[0065] The composition was analyzed, and the results were as follows: component (A) L-MGDA.3Na content: 40.11 wt%; component (B) sodium N,N-dimethylglycinate: 0.6 wt%; component (C) sodium sulfite: 0.3 wt%; and the balance: water.

[0066] The calcium ion binding capacity of the storage-stable MGDA.3Na composition was 151.7 (mg Ca 2+ / g chelating agent).

[0067] Example 2

[0068] 1) Preparation of component (A) MGDA.3Na: DL-alanine as raw material, MGDA.3Na was synthesized by Strecker reaction

[0069] The same preparation process parameters as in Example 1 were used, DL-alanine was used as raw material instead of L-alanine, and other operations were unchanged to prepare a DL-MGDA.3Na aqueous solution with a concentration of 40.37 wt%, wherein the NTA.3Na content was 0.06 wt%, the formaldehyde and formaldehyde releasing body content was 19.5 ppm, the chlorine content was 0.001 wt%, and the Hazen color number was 205.

[0070] 2) Preparation of storage-stable MGDA.3Na composition:

[0071] 770.6 g of the DL-MGDA.3Na aqueous solution with a concentration of 40.37 wt% prepared in step 1) was added with 3.2 g of solid sodium N,N-dimethylglycinate and 4.7 g of solid sodium sulfite at room temperature to prepare a total of 778.5 g of storage-stable DL-MGDA.3Na composition.

[0072] Through analysis testing, the content of component (A) L-MGDA.3Na was 39.96 wt%, the content of component (B) sodium N,N-dimethylglycinate was 0.4 wt%, the content of component (C) sodium sulfite was 0.6 wt%, and the balance was water.

[0073] The calcium ion binding capacity of the storage-stable MGDA.3Na composition was 151.2 (mg Ca 2+ / g chelating agent).

[0074] Example 3

[0075] 1) Preparation of component (A) MGDA.3K: D-alanine as raw material, MGDA.3K was synthesized by Strecker reaction

[0076] The same preparation process parameters as in Example 1 were used, D-alanine was used as raw material instead of L-alanine, and an aqueous potassium hydroxide solution was used instead of an aqueous sodium hydroxide solution to prepare a D-MGDA.3K aqueous solution with a concentration of 45.46 wt%, wherein the NTA.3K content was 0.10 wt%, the formaldehyde and formaldehyde releasing body content was 22.0 ppm, the chlorine content was 0.001 wt%, and the Hazen color number was 195.

[0077] 2) Preparation of storage-stable MGDA.3K composition:

[0078] Take the concentration of 45.39wt% of D-MGDA.3K aqueous solution prepared in step 1) 806.9g, room temperature, add solid N,N-diethylglycine potassium 3.9g and solid potassium sulfite 3.2g, to prepare a total of 814.0g of storage-stable D-MGDA.3K composition solution.

[0079] By analyzing the test, the content of component (A) D-MGDA.3K is 45.00wt%, component (B) N,N-ethyl glycine potassium is 0.48wt%, component (C) potassium sulfite is 0.39wt%, and the balance is water;

[0080] The calcium ion binding capacity of the storage-stable MGDA.3K composition is 145.0(mg Ca 2+ / g fold chelator).

[0081] Example 4

[0082] 1) Preparation of component (A) MGDA.3Na: L-alanine as raw material, MGDA.3Na was synthesized by chloroacetic acid method

[0083] Put 90.0g(1mol)L-alanine, sodium hydroxide 24.5g(0.6mol) and 120g deionized water into the reaction bottle, stir and mix uniformly, then dissolve 200.5g(2.1mol) chloroacetic acid in 143.5g deionized water and 50% sodium hydroxide solution 368g(4.6mol), load into constant pressure dropping funnel respectively, preheat the reaction bottle system temperature to 82℃, while adding chloroacetic acid and liquid alkali aqueous solution, control the dropping speed, keep the reaction temperature at 83-87℃, pH value at 10.5-11.0, drop for 2h; Under the condition of-0.003MPa negative pressure, the water in the reaction system is removed step by step, and the temperature is kept at 85℃ for 1h after the dropping is finished; After the concentration is kept, the temperature is gradually reduced to 40℃, the salt is filtered, and the filtrate is diluted with water to 40.75wt% L-MGDA.3Na aqueous solution, in which the chloride ion content is 2.58wt%, and the Hazen color number is 230.

[0084] 2) Preparation of storage-stable MGDA.3Na composition:

[0085] Take the concentration of 40.75wt% of L-MGDA.3Na aqueous solution prepared in step 1) 630.1g, room temperature, add solid N,N-diethylglycine sodium 5.2g and solid sodium bisulfite 5.2g, stir and dissolve to get a total of 640.5g of storage-stable L-MGDA.3Na composition solution.

[0086] By analytical test, wherein component (A) L-MGDA.3Na content is 40.09wt%, component (B) N,N-dipropyl glycine sodium is 0.81wt%, component (C) sodium bisulfite is 0.81wt%, and the balance is water;

[0087] The calcium ion binding capacity of the storage-stable MGDA.3Na composition is 152.8 (mg Ca 2+ / g per 100 chelator).

[0088] Example 5

[0089] 1) Preparation of component (A) MGDA.3K: L-alanine as raw material, MGDA.3K is synthesized by chloroacetic acid method

[0090] Put 90.0g (1mol) L-alanine, 34.0g (0.6mol) potassium hydroxide and 120g deionized water into the reaction bottle, stir and mix uniformly, then dissolve 200.5g (2.1mol) chloroacetic acid in 143.5g deionized water and dissolve 271.1g (4.6mol) potassium hydroxide in 406.5g deionized water, load into constant pressure dropping funnels respectively, preheat the reaction bottle system temperature to 82℃, while dropping chloroacetic acid and potassium hydroxide aqueous solution, control the dropping speed, keep the reaction temperature at 83-87℃, pH value at 10.5-11, drop for 2h; under the condition of-0.003MPa negative pressure, gradually remove water from the reaction system at the same time, after dropping is completed, keep 85℃ for 1h, after concentration, gradually cool to 40℃, filter the salt, dilute the filtrate with water to 45.68wt% L-MGDA.3K aqueous solution, wherein the chloride ion content is 2.55%, and the Hazen color number is 225.

[0091] 2) Preparation of storage-stable MGDA.3K composition:

[0092] Take 664.4g of the 45.60wt% MGDA.3K aqueous solution prepared in step 1), add 4.6g of solid N,N-dimethyl glycine potassium and 4.6g of solid sodium bisulfite at room temperature, stir and dissolve to obtain a total of 673.6g of storage-stable L-MGDA.3K composition solution.

[0093] By analytical test, wherein component (A) L-MGDA.3K content is 44.98%, component (B) N,N-dimethyl glycine potassium is 0.68wt%, component (C) sodium bisulfite is 0.68wt%, and the balance is water;

[0094] The calcium ion binding capacity of the storage-stable MGDA.3K composition is 142.5 (mg Ca 2+ / g per 100 chelator).

[0095] Example 6

[0096] Preparation of storage-stable MGDA.3Na composition (MGDA.3Na prepared using different post-treatment conditions, using L-alanine as raw material)

[0097] The specific method is as follows: using the process parameters of Example 1, 1500 g of storage-stable L-MGDA.3Na composition solution was prepared.

[0098] The above raw material was divided into 15 batches, and different process parameters (temperature, pressure, time) were used for post-treatment to verify the stability of the composition to MGDA and the influence on the calcium ion chelating ability:

[0099] Each batch of 100 g L-MGDA.3Na composition solution was sequentially subjected to atmospheric reflux and pressurized post-treatment in a reflux reaction bottle and a sealed autoclave to change the state and component of the L-MGDA.3Na composition product. After cooling, the weight was measured, and the main content and calcium ion chelating ability indicators were analyzed under atmospheric pressure. The results are shown in Table 1.

[0100] Table 1 Data changes of MGDA.3Na composition using different process parameters for post-treatment

[0101]

[0102] From the data in Table 1 above, it can be seen that different post-treatment process conditions can affect the calcium ion chelating ability of the L-MGDA.3Na aqueous solution. First, it is necessary to ensure that the product does not decompose. Within a certain temperature and pressure treatment range, the actual calcium ion chelating ability of the product composition is first increased and then stabilized.

[0103] Comparative Example 1

[0104] Component (A) Preparation of MGDA.3Na: MGDA.3Na was synthesized by reaction using L-alanine as raw material and chloroacetic acid method

[0105] With reference to the method and preparation process of application patent CN 109369428 A example 1, 90.0 g (1 mol) of L-alanine, 24.5 g (0.6 mol) of sodium hydroxide and 120 g of deionized water are added to a reaction bottle, after stirring and mixing uniformly, 200.5 g (2.1 mol) of chloroacetic acid is dissolved in 143.5 g of deionized water and 368 g (4.6 mol) of 50 wt% sodium hydroxide aqueous solution is loaded into a constant pressure dropping funnel respectively, the reaction bottle system is preheated to 82°C, and chloroacetic acid and liquid alkali aqueous solution are added dropwise at the same time, the dropping speed is controlled, the reaction temperature is kept at 83-87°C, and the pH value is kept at 10.5-11.0, the dropping is carried out for 2 h; under the condition of -0.003 MPa negative pressure, the water in the reaction system is removed at the same time, after 1 h of insulation at 85°C after the dropping is completed, the temperature is gradually reduced to 40°C, the salt is filtered, and the filtrate is diluted with water to obtain an L-MGDA.3Na aqueous solution, with a total amount of 643.5 g.

[0106] The prepared L-MGDA.3Na aqueous solution is tested by analysis, wherein the L-MGDA.3Na content is 40.03 wt%, the chloride ion content is 2.58 wt%, the product Hazen color number is 210, and the calcium ion binding capacity is 152.5 (mg Ca 2+ / g chelating agent).

[0107] Comparative example 2

[0108] Preparation of component (A) MGDA.3Na: L-alanine is used as raw material, and MGDA.3Na is synthesized by Strecker reaction

[0109] Referring to the preparation method of CN 105531255 B Example 1 (pages 16-17 L-MGDA.3Na aqueous solution): a flask was charged with 310 g of deionized water, preheated to 40°C, 180 g of L-alanine (2.0 mol) was added, 104 g of 50 wt% sodium hydroxide aqueous solution (1.30 mol) was added into the slurry within 30 min, the temperature rose to 60°C, and stirring was performed to obtain a clear solution of 593.5 g. 500 ml of water was added to the stirred flask and heated to 40°C. The above-mentioned 593.5 g of L-alanine solution (2.0 mol), 406.8 g of 30 wt% formaldehyde aqueous solution (2.033 mol) and 55 g of hydrogen cyanide (2.037 mol) were simultaneously added into the reaction flask within 1 h. Then the remaining 55 g of hydrogen cyanide (2.037 mol) was added within 1 h at 40°C, and the mixture was kept for 1 h to obtain a methylglycine-N,N-diacetonitrile mixed solution of 1110 g. 400 g of 50% sodium hydroxide solution (5.0 mol) was added to the stirred flask, preheated to 30°C, and the above-prepared dinitrile mixed solution was slowly added dropwise into the lye. During the feeding, the temperature was maintained at 28-32°C by external cooling, and after the feeding was completed, the reaction mixture was kept for 1 h and then refluxed at 90-95°C for 6 h to complete the saponification and remove the residual ammonia in the system. Activated carbon was used for decolorization, and after concentration, an L-MGDA.3Na aqueous solution was obtained, with a total of 1286.8 g.

[0110] The prepared L-MGDA.3Na aqueous solution was analyzed and tested, wherein the content of L-MGDA.3Na was 40.03 wt%, the content of NTA.3Na was 0.08 wt%; the product had a Hazen color number of 225, and the calcium ion binding capacity was 151.3 (mg Ca 2+ / g chelating agent).

[0111] Comparative Example 3

[0112] Preparation of component (A) MGDA.3Na: using L-alanine as raw material, MGDA.3Na was prepared under different post-treatment conditions

[0113] The component (A) raw material MGDA.3Na aqueous solution prepared in Comparative Example 2 was divided into 15 batches, and different process parameters (temperature, pressure, time) post-treatment was carried out to verify the influence of different processes on the stability of MGDA and the calcium ion chelating capacity. In the reflux reaction flask and the sealed autoclave, 100 g of L-MGDA.3Na aqueous solution was subjected to atmospheric reflux and pressurized post-treatment, the state and component of the L-MGDA.3Na aqueous solution were changed, and after cooling, the weight was measured. The main content and calcium ion chelating capacity indicators were analyzed by sampling under atmospheric pressure, and the results are shown in Table 2.

[0114] Table 2 Data changes of MGDA.3Na treated by different process parameters

[0115]

[0116] From the data in Table 2, the same rule as the data in Table 1 is obtained. First, the product should not be decomposed. In a specific temperature and pressure treatment range, the product with the composition in Table 1 has more stable chelating ability, better color number stability, and smaller fluctuation range. The stability of the product composition is better at 160-210°C.

[0117] Comparative Example 4

[0118] Referring to Example 1, the difference is only that in step 2) the preparation of the MGDA.3Na composition, N,N-dimethyl glycine sodium is not added, and other operations and conditions are unchanged, and the composition is prepared. Among them, the content of L-MGDA.3Na is 40.15wt%, sodium sulfite is 0.31wt%, the product Hazen color number is 230, and the calcium ion binding capacity of the product composition is 150.5(mg Ca 2+ / g per hundred chelating agent).

[0119] Comparative Example 5

[0120] Referring to Example 1, the difference is only that in step 2) the preparation of the MGDA.3Na composition, sodium sulfite is not added, and other operations and conditions are unchanged, and the composition is prepared. Among them, the content of L-MGDA.3Na is 40.12wt%, N,N-dimethyl glycine sodium is 0.61wt%, the product Hazen color number is 235, and the calcium ion binding capacity of the product composition is 151.2(mg Ca 2+ / g per hundred chelating agent).

[0121] Comparative Example 6

[0122] Referring to Example 1, the difference is only that in step 2) the preparation of the MGDA.3Na composition, sodium sulfite is replaced by sodium sulfate, and other operations and conditions are unchanged, and the composition is prepared. Among them, the content of L-MGDA.3Na is 40.11wt%, N,N-dimethyl glycine is 0.60wt%, sodium sulfate is 0.3wt%, the product Hazen color number is 240, and the calcium ion binding capacity of the product composition is 151.5(mg Ca 2+ / g per hundred chelating agent).

[0123] Example 7

[0124] MGDA.3Na(3K) composition storage time and calcium ion chelating capacity change data

[0125] The methylglycine-N,N-diacetic acid trisalkali metal salt compositions obtained in Examples 1-5 and Comparative Examples 1-6 above were stored at the same temperature (23-25°C), in the dark, in a sealed, air-tight container, and the stability was verified, and the parameters were measured under the same analysis conditions (23°C). The results of Examples 1-5 are shown in Table 3, and the results of Comparative Example 1-6 are shown in Table 4.

[0126] Table 3 Data on changes in calcium ion chelating ability of MGDA.3Na (3K) composition of Examples 1-5 with storage time

[0127]

[0128]

[0129] Table 4 Data on changes in calcium ion chelating ability of MGDA.3Na composition of Comparative Examples 1-6 with storage time

[0130]

[0131] As can be seen from the data in Table 3 above, the Strecker method products of Examples 1-3 showed a decrease of about 2-3% in calcium ion chelating ability after about 3 years, and a decrease of about 3% at most after 4 years. The chloroacetic acid method products of Examples 4-5 showed a decrease of 2-3% after about 2 years, and a decrease of about 4% at most after 3 years.

[0132] As can be seen from the data in Table 4 above, the chloroacetic acid method products of Comparative Example 4 and Comparative Example 1 showed a significant decrease after 8 months, and a decrease of 5-8% after 2 years. The Strecker method products of Comparative Example 2 and Comparative Example 3, which did not contain component (B) and (C), showed a significant decrease in chelating ability of 3-5% after about 2 years, and a decrease of 7% after 3 years. Comparative Example 4 did not contain sodium N,N-dimethylglycinate, Comparative Example 5 did not contain sodium sulfite, and Comparative Example 6 used sodium sulfate instead of sodium sulfite. These three comparative examples essentially contained only a single component, and the results were worse than those of Comparative Example 1. In terms of calcium ion chelating ability, the products were substantially the same after about 2 years, but the products showed a decrease of varying degrees after 2 years, and a decrease of about 6% at most. However, the results were better than those of Comparative Examples 2 and 3, which did not contain the components.

[0133] In summary, the stability and chelating ability of the product compositions of the examples were significantly better than those of the comparative examples.

[0134] Example 8

[0135] Data on changes in main content of MGDA.3Na (3K) composition with storage time

[0136] The methyl glycine-N, N-diacetic acid trialkali salt compositions obtained in Examples 1-5 and Comparative Examples 1-6 above were stored at the same temperature (23-25°C) in the dark, sealed and air-tight, and the stability was verified. The parameters were measured under the same analysis conditions (23°C), and the results of Examples 1-5 are shown in Table 5, and the results of Comparative Example 1-6 are shown in Table 6.

[0137] Table 5 Storage time and main content change data of MGDA.3Na (3K) composition of Examples 1-5

[0138]

[0139]

[0140] Table 6 Storage time and main content change data of MGDA.3Na composition of Comparative Examples 1-6

[0141]

[0142] As can be seen from the data in Table 5 above, the Strecker method products of Examples 1-3 have a decrease in main content of <0.5% after 4 years, and the chloroacetic acid method products of Examples 4-5 have a decrease after about 2 years, and a decrease of <0.5% after 3 years at most.

[0143] As can be seen from the data in Table 6 above, the chloroacetic acid method products of Comparative Example 4 and Comparative Example 1 have a decrease in main content after 8 months, and a decrease of 1.5% after 2 years of storage. Based on Example 1, the Strecker method products of Comparative Example 2 and Comparative Example 3, which do not add components (B) and (C), have a decrease in main content of about 1% after about 3 years of storage. Comparative Example 4 does not add sodium N, N-dimethylglycinate, Comparative Example 5 does not add sodium sulfite, and Comparative Example 6 uses sodium sulfate instead of sodium sulfite. These three comparative examples essentially add only a single component, and Comparative Example 1 is worse than the effect, and the product specifications are basically the same in terms of main content, and at most decrease by <0.5%, but the effect is better than that of Comparative Example 2 and Comparative Example 3 which do not add.

[0144] In summary, the stability of the product composition and the stability of the main content of the examples are significantly better than those of the comparative examples under the same storage time.

[0145] Example 9

[0146] Storage time and color number and appearance change data of MGDA.3Na (3K) composition

[0147] The methylglycine-N,N-diacetic acid tris alkali metal salt compositions obtained in Examples 1-5 and Comparative Examples 1-6 above were stored at the same temperature (23-25°C) in the dark, sealed and air-tight, and the stability was verified. The color number and appearance were measured under the same analysis conditions (23°C), and the results are shown in Table 7.

[0148] Table 7 Storage time and color number and appearance change data of MGDA.3Na composition

[0149]

[0150]

[0151] As can be seen from the data in Table 7 above, the color number of the Strecker method products of Examples 1-3 increased by 3-5% in 3 years. The color number of the Strecker method products of Comparative Example 2 and Comparative Example 3 increased by 20-30% in 3 years without the addition of the composition. Comparative Example 4 did not add sodium N,N-dimethylglycinate, Comparative Example 5 did not add sodium sulfite, and Comparative Example 6 used sodium sulfate instead of sodium sulfite. These three comparative examples essentially added only a single component, and the effect of Comparative Example 1 was worse, with an increase of 8-13% in color number. However, the effect was better than that of Comparative Example 2 and Comparative Example 3 without the addition of the composition. The color number of the chloroacetic acid method products of Examples 4-5 increased by 6-8%, and the color number of the product of Comparative Example 1 increased significantly by 48%.

[0152] Example 10

[0153] Storage time and calcium ion chelating ability change data of MGDA.3Na composition

[0154] Referring to Example 6 above, 40 wt% MGDA.3Na compositions were prepared at different reaction temperatures by changing the process conditions. Referring to Comparative Example 3 above, 40 wt% MGDA.3Na aqueous solutions were obtained at different reaction temperatures by changing the process conditions. The stability was verified by storing the compositions at the same temperature (23-25°C) in the dark, sealed and air-tight. The parameters were measured under the same analysis conditions (23°C), and the results are shown in Table 8.

[0155] Table 8 Storage time and calcium ion chelating ability change data of MGDA.3Na composition and aqueous solution of Comparative Example

[0156]

[0157]

[0158] As can be seen from Table 8, the MGDA.3Na aqueous solution of the comparative example, after high temperature and high pressure treatment at different times, although the main content of the product is maintained at 39.90% to 40.10% within 2 years, the chelating ability stability has a tendency of different degrees of decline in calcium ion chelating ability within 2 years of storage, and the overall decline ratio is 5% to 10%, which is different under different process conditions, while the overall decline ratio of the MGDA.3Na composition product of the example is about 2% within 2 years.

[0159] Although the content of the present application has been described in detail by the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present application. Those skilled in the art can understand that some modifications or adjustments can be made to the present application under the teaching of the present specification. These modifications or adjustments should also be within the scope defined by the claims of the present application.

Claims

1. A storage-stable methylglycine-N,N-diacetic acid trialkali metal salt composition characterized in that, comprising the following components by mass percentage: Component (A) 18.0-45.0 wt% of a trialkali metal salt of methylglycine-N,N- diacetic acid; Component (B) 0.1-1.0 wt% of an alkali metal salt of N,N-dialkylglycine; Component (C) 0.1-1.0 wt% of a sulfite salt; and 53.0-81.8 wt% of water; the sum of the contents of each component totaling 100 wt%.

2. The methylglycine-N,N-diacetic acid trialkali metal salt composition according to claim 1, characterized in that, comprising 25.0-40.0 wt% of a trialkali metal salt of methylglycine-N,N- diacetic acid.

3. The methylglycine-N,N-diacetic acid trialkali metal salt composition according to claim 1, characterized in that, comprising 58.0-75.0 wt% of water.

4. The methylglycine-N,N-diacetic acid trialkali metal salt composition according to claim 1, characterized in that, Component (A) the trialkali metal salt of methylglycine-N,N-diacetic acid is at least one of a trisodium salt of methylglycine-N,N-diacetic acid and a tripotassium salt of methylglycine-N,N-diacetic acid.

5. The methylglycine-N,N-diacetic acid trialkali metal salt composition according to claim 4, characterized in that, Component (A) the trialkali metal salt of methylglycine-N,N-diacetic acid is at least one of a 30 wt% aqueous solution of MGDA·3Na and a 40 wt% aqueous solution of MGDA·3Na commercially available.

6. The methylglycine-N,N-diacetic acid trialkali metal salt composition according to claim 1, characterized in that, Component (A) the trialkali metal salt of methylglycine-N,N-diacetic acid is an aqueous solution with a concentration of 18.0-45.0 wt%.

7. The methylglycine-N,N-diacetic acid trialkali metal salt composition according to claim 6, characterized in that, Component (A) the trialkali metal salt of methylglycine-N,N-diacetic acid is an aqueous solution with a concentration of 18.0-45.0 wt% prepared by a chloroacetic acid method or a Strecker method using hydrocyanic acid.

8. The methylglycine-N,N-diacetic acid trialkali metal salt composition according to claim 1, characterized in that, Component (B) the alkali metal salt of N,N-dialkylglycine is at least one of sodium N,N-dimethylglycinate, sodium N,N-diethylglycinate, sodium N,N-dipropylglycinate, potassium N,N-dimethylglycinate, potassium N,N-diethylglycinate, and potassium N,N-dipropylglycinate.

9. The methylglycine-N,N-diacetic acid trialkali metal salt composition according to claim 1, characterized in that, Component (C) the sulfite salt is at least one of sodium sulfite, potassium sulfite, sodium bisulfite, and potassium bisulfite.

10. The methylglycine-N,N-diacetic acid trialkali metal salt composition according to claim 1, characterized in that, the water, wherein the water is introduced from the raw materials of components (A)-(C).

11. A process for the preparation of a storage-stable methylglycine-N,N- diacetic acid trialkali metal salt composition according to any one of claims 1 to 10, characterized in that, The trialkali metal salt of methylglycine-N,N-diacetic acid, the alkali metal salt of N,N-dialkylglycine, the sulfite salt, and the water are weighed according to the proportions respectively, and mixed uniformly to obtain the product.

12. The method of claim 11, wherein, The alkali metal salt of N,N-dialkylglycine and the sulfite salt are in the form of a solid or an aqueous solution, and are mixed uniformly with the trialkali metal salt of methylglycine-N,N-diacetic acid to prepare the trialkali metal salt of methylglycine-N,N-diacetic acid composition.

13. Use of the storage-stable trialkali metal salt of methylglycine-N,N-diacetic acid composition of any one of claims 1-10 or the storage-stable trialkali metal salt of methylglycine-N,N-diacetic acid composition prepared by the method of claim 11 or 12 for stabilizing the storage and / or transportation of the trialkali metal salt of methylglycine-N,N-diacetic acid and improving the stability of the chelating ability of the metal ions of the composition product.

14. Use according to claim 13, characterized in that, for improving the stability of the chelating ability of calcium ions and magnesium ions. for improving the stability of the chelating ability of calcium ions and magnesium ions.

15. Use of the storage-stable trialkali metal methylglycine-N,N-diacetic acid salt composition according to any one of claims 1 to 10 or of the storage-stable trialkali metal methylglycine-N,N-diacetic acid salt composition prepared by the method according to claim 11 or 12 in the field of domestic washing, water softening and sewage treatment.

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