Preparation method of electronic-grade trihydroxymethyl aminomethane

Abstract

The invention discloses a preparation method of electronic-grade tris (hydroxymethyl) aminomethane, which comprises the following steps: tris (hydroxymethyl) aminomethane is prepared into an aqueous solution, the aqueous solution passes through a chromatographic column, the filler of the chromatographic column is chelate resin or cation exchange resin, and the chelate resin or cation exchange resin is subjected to transformation pretreatment by using ammonia water before being filled; the obtained tris (hydroxymethyl) aminomethane solution is subjected to circulating filtration through a three-stage membrane module filtration system; adding a chelating agent to carry out chelating concentration treatment, and then concentrating to remove part of water; carrying out gradient cooling crystallization on the sample; and sequentially centrifuging and drying the cooled and crystallized trihydroxymethyl aminomethane solution to obtain the electronic-grade trihydroxymethyl aminomethane. The metal ion content of the finally obtained trihydroxymethyl aminomethane is 10 ppb or below, after further treatment, the metal ion content can be controlled to 1 ppb or below, operation is easy, and industrial production is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of compound purification, in particular to a preparation method of electronic-grade tris base. BACKGROUND

[0002] Tris base, also known as tris(hydroxymethyl)aminomethane (Tris), has a molecular formula of C4H 11 NO3. Biological-grade tris base is an important biochemical reagent widely used in biomedical research, molecular biology experiments, and cell culture, etc. Electronic-grade tris base can be applied to the field of electronic manufacturing, such as wafer cleaning, photoresist dilution, and etching, etc. key processes to ensure the high-quality production of electronic components. Therefore, there is a higher requirement for the content of metal ions in tris base.

[0003] However, due to the rich hydrogen bond donors and acceptors in its molecular structure, tris base has good complexing performance and can form stable complexes with metal ions, so it is difficult to remove the metal ions contained in tris base to reduce its content to the requirements of electronic grade.

[0004] Currently, the traditional method for removing metal ions of electronic-grade tris base is recrystallization. However, recrystallization has quite strict requirements for water quality, generally less than 1 ppb of metal ions in pure water, and it is only possible to reduce the metal ions in tris base to less than 10 ppb under the condition of more than 5 times of recrystallization. However, the production cycle of using recrystallization process is long, the yield is extremely low, and it is not conducive to industrial mass production, so a simpler method is needed to remove the metal ions in tris base. SUMMARY

[0005] In order to solve the technical problems existing in the prior art, the present application provides a preparation method of electronic-grade tris base, comprising the following steps:

[0006] Step 1: tris base is prepared into an aqueous solution, and passed through a chromatographic column, the filler of the chromatographic column is chelating resin or cation exchange resin, and the chelating resin or cation exchange resin is first pretreated by transformation with ammonia before packing;

[0007] Step 2: the tris base solution obtained in step 1 is subjected to cyclic filtration by a three-stage membrane module filtration system;

[0008] Step 3: a chelating agent is added to the tris base solution obtained in step 2 for chelation and concentration treatment, and part of the water is removed by concentration;

[0009] Step 4: Gradient cooling crystallization of the chelated and concentrated solution of the tris-hydroxymethyl aminomethane in step 3;

[0010] Step 5: Centrifugation and drying of the solution of the tris-hydroxymethyl aminomethane after the cooling crystallization in step 4 to obtain the electronic grade tris-hydroxymethyl aminomethane.

[0011] By adopting the above technical solution, the resin is converted into ammonia type, effectively avoiding the competition adsorption and neutralization phenomenon, greatly improving the yield of the finished product. And adopting multi-stage circulating filtration, the metal ions in the solution are enriched between the filter core and the filter shell, which is helpful to remove the metal ions in the product. Adding a small amount of chelating agent in the concentration process can effectively remove the metal ions of multiple valence states, further reducing the metal ions not adsorbed by the resin. Adopting constant temperature stirring and gradient cooling makes the size of the precipitated crystals uniform, and the purity is higher and the impurities are less. Therefore, through the combination of the above steps, the metal ions in the obtained tris-hydroxymethyl aminomethane are reduced to less than 10ppb.

[0012] Preferably, in step 1, when preparing the tris-hydroxymethyl aminomethane aqueous solution, medical grade tris-hydroxymethyl aminomethane is used as raw material and water is ultrapure water.

[0013] Preferably, the concentration of the prepared tris-hydroxymethyl aminomethane aqueous solution is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, etc. Any value within the range of 5% to 45% is within the protection scope of the present application and is not limited to the above listed values.

[0014] Preferably, in step 1, the concentration of the ammonia solution is 4%, 5%, 6%, 7%, 8%, 9%, 10%, and any value within the range of 4% to 10% is within the protection scope of the present application and is not limited to the above listed values.

[0015] Preferably, in step 1, after treating the chelating resin or cation exchange resin filler of the chromatography column with ammonia water, the column is washed with pure water until the pH is 7 to 8.

[0016] Preferably, in step 2, when the tris-hydroxymethyl aminomethane solution passes through the three-stage membrane assembly filtration system, the concentrated solution in the membrane assembly is discharged every 10 to 60 minutes, and the circulating filtration time is 1 to 10 hours.

[0017] Through the technical scheme, the concentrated solution in the filter core and filter shell interlayer is discharged at regular time, so that the metal ions in the sample can be removed more effectively.

[0018] Preferably, in step 3, the chelating agent is selected from one or more of EDTA, 15-crown-5, triethylenetetramine and DTPA.

[0019] Preferably, in step 3, the amount of the chelating agent added is 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1% of the solid mass of the tris-hydroxymethyl aminomethane in step 1, and any value within the range of 0.01% to 0.1% is within the protection scope of the present application and is not limited to the values listed above.

[0020] Preferably, in step 3, the concentration of the tris-hydroxymethyl aminomethane aqueous solution after chelation and concentration is 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, and any value within the range of 40% to 65% is within the protection scope of the present application and is not limited to the values listed above.

[0021] Preferably, in step 4, the specific steps of the gradient crystallization are: after the temperature of the concentrated solution is reduced to 25-50°C, the concentrated solution is incubated and stirred for 1-2h; then the temperature of the concentrated solution is reduced to 0-15°C, seed crystals are added, and constant temperature stirring is performed for 4-8h.

[0022] Preferably, in step 4, the stirring speed is 15-30rad / min.

[0023] Preferably, in step 5, the drying temperature is 60-90°C, and the drying time is 8-24h.

[0024] Preferably, in step 1, when preparing the tris-hydroxymethyl aminomethane aqueous solution, heating and stirring are performed at 65-95°C, and after complete dissolution, water bath cooling is performed to 20-35°C.

[0025] Preferably, in step 1, when using ammonia water to convert the chelating resin or cation exchange resin filler of the chromatographic column to the ammonia type, the flow rate of the ammonia water solution is 50-150mL / min.

[0026] Preferably, in step 2, the membrane thickness of the membrane assembly filtration system is 10μm, 0.45μm, 0.22μm in sequence.

[0027] Preferably, in step 3, the temperature of the chelating concentration is 80-95℃, and the vacuum degree is 0.08-0.1 MPa.

[0028] Preferably, the preparation method further comprises step 6: weighing the electronic-grade trimethylol aminomethane obtained after drying in step 5, preparing an aqueous solution, then performing secondary gradient cooling crystallization, and then sequentially performing centrifugation and drying on the trimethylol aminomethane solution after the secondary cooling crystallization to obtain the target product.

[0029] Preferably, the specific steps of the secondary cooling crystallization are: after the temperature of the aqueous solution is reduced to 25-50℃, the solution is kept at the temperature and stirred for 1-2h; then after the temperature of the concentrated solution is reduced to 0-15℃, seed crystals are added, and the solution is kept at the temperature and stirred for 4-8h.

[0030] Preferably, the stirring speed is 15-30 rad / min.

[0031] Preferably, the drying temperature is 60-90℃, and the drying time is 8-24h.

[0032] Through the above technical solution, the metal ion content of the trimethylol aminomethane can be reduced to below 1 ppb after step 6, reaching the requirements of higher-grade electronic trimethylol aminomethane.

[0033] In summary, the present application has the following beneficial effects:

[0034] 1. The preparation method disclosed in the present application converts the resin into an amine type, effectively avoiding competitive adsorption and neutralization, greatly improving the yield of the finished product. Moreover, multi-stage circulation filtration is adopted, so that the metal ions in the solution are enriched between the filter core and the filter shell, which helps to remove the metal ions in the product, and the concentrated solution in the filter core and filter shell interlayer is discharged at regular intervals, which can more effectively remove the metal ions in the product. A small amount of chelating agent is added during the concentration process, which can effectively remove the metal ions of multiple valence states and further remove the metal ions that have not been adsorbed by the resin. Constant temperature stirring and gradient cooling are adopted to make the precipitated crystals uniform in size, higher in purity, and less impurities. Therefore, through the combination of the above steps, the metal ion content of the obtained trimethylol aminomethane can be reduced to below 10 ppb, reaching the requirements of electronic trimethylol aminomethane.

[0035] 2. The preparation method disclosed in the present application can further reduce the metal ion content of trimethylol aminomethane to below 1 ppb after further processing, reaching the requirements of higher-grade electronic trimethylol aminomethane. DETAILED DESCRIPTION

[0036] EMBODIMENT

[0037] The following example is a method for preparing electronic grade tris-hydroxymethyl aminomethane.

[0038] Example 1

[0039] Weigh 1000g of pharmaceutical grade tris-hydroxymethyl aminomethane, add 6000g of ultrapure water, heat and stir at 80°C until completely dissolved, and then cool to 25°C in a water bath. Weigh 350g of chelating resin and load it into a 500mL HDPE chromatographic column, rinse with ultrapure water until the pH is 5-6. Prepare 2000mL of 8% ammonia solution and rinse the chromatographic column at a constant flow rate of 50mL / min, leave overnight and then rinse with ultrapure water until the pH is 7-8. Pass the obtained tris-hydroxymethyl aminomethane aqueous solution through the regenerated ion exchange column at a flow rate of 100mL / min, and collect the effluent.

[0040] Pass the tris-hydroxymethyl aminomethane aqueous solution after ion exchange through a three-stage membrane assembly filtration system in turn at a constant speed of 10μm, 0.45μm, and 0.22μm, and remove the concentrated liquid every 30min (liquid in the filter core and filter shell interlayer), and circulate for 2h.

[0041] Add 0.5g of 15-crown-5 to the tris-hydroxymethyl aminomethane aqueous solution after membrane filtration, turn on the stirring and heating device, set the concentration temperature to 85°C, control the vacuum degree to 0.09MPa, and concentrate under vacuum, and control the concentration of the tris-hydroxymethyl aminomethane aqueous solution after concentration to 50%.

[0042] Transfer the concentrated tris-hydroxymethyl aminomethane aqueous solution to a crystallization cylinder, set the stirring speed to 25rad / min, reduce the concentration liquid temperature to 35°C, and keep stirring for 1.5h, then reduce the concentration liquid temperature to 8°C, set the stirring speed to 25rad / min, add seed crystals, and keep stirring at constant temperature for 6h.

[0043] Transfer the crystallized tris-hydroxymethyl aminomethane solution to a centrifuge and spin dry. Move the centrifuged product to a drying oven, set the drying oven temperature to 80°C, and continuously dry for 16h, and collect 455.2g of product, with a yield of 45.52%. Repeat the above steps multiple times to prepare tris-hydroxymethyl aminomethane with higher purity for further processing.

[0044] Example 2

[0045] Weigh 1000g of medical grade Tris, add 19000g of ultrapure water, heat and stir at 65°C until completely dissolved. After complete dissolution, cool to 20°C in a water bath. Weigh 350g of 001*7 cation exchange resin, load into a 500mL HDPE chromatography column, rinse with ultrapure water until pH is 5-6. Prepare 2000mL of 4% ammonia solution, rinse the chromatography column at a constant flow rate of 50mL / min, leave overnight and then rinse with ultrapure water until pH is 7-8. Pass the obtained Tris aqueous solution through the regenerated ion exchange column at a flow rate of 50mL / min, collect the effluent.

[0046] Pass the ion-exchanged Tris aqueous solution through a three-stage membrane assembly filtration system in turn at a constant rate of 10μm, 0.45μm, and 0.22μm, and remove the concentrated liquid every 60min (liquid in the filter core and filter shell interlayer), and circulate for 6h.

[0047] Add 0.1g of triethylenetetramine to the membrane-filtered Tris aqueous solution, turn on the stirring and heating device, set the concentration temperature to 80°C, control the vacuum degree to 0.1MPa, concentrate under vacuum, and control the concentration of the concentrated Tris aqueous solution to 65%.

[0048] Transfer the concentrated Tris aqueous solution to a crystallization cylinder, set the stirring speed to 15rad / min, reduce the concentration liquid temperature to 50°C, and maintain stirring for 1h. Then reduce the concentration liquid temperature to 15°C, set the stirring speed to 15rad / min, add seed crystals, and maintain constant temperature stirring for 4h.

[0049] Transfer the crystallized Tris solution to a centrifuge and spin dry. Transfer the centrifuged product to a drying oven, set the drying oven temperature to 90°C, and continuously dry for 8h. Collect 483.6g of product, with a yield of 48.36%.

[0050] Example 3

[0051] Weigh 1000g of medical grade Tris, add 1200g of ultrapure water, heat and stir at 95°C until completely dissolved. After complete dissolution, cool to 35°C in a water bath. Weigh 350g of chelating resin, load into a 500mL HDPE chromatography column, rinse with ultrapure water until pH is 5-6. Prepare 2000mL of 10% ammonia solution, rinse the chromatography column at a constant flow rate of 150mL / min, leave overnight and then rinse with ultrapure water until pH is 7-8. Pass the obtained Tris aqueous solution through the regenerated chelating resin column at a flow rate of 150mL / min, collect the effluent.

[0052] The ion-exchanged aqueous solution of tris-hydroxymethyl aminomethane was filtered through a three-stage membrane assembly filter system with 10 μm, 0.45 μm and 0.22 μm membranes in sequence at a constant speed. The concentrated solution was discharged every 20 min from the space between the filter core and the filter shell, and the filtration was repeated for 1 h.

[0053] EDTA was added to the membrane-filtered aqueous solution of tris-hydroxymethyl aminomethane, and the stirring and heating devices were turned on. The concentration temperature was set to 95°C, and the vacuum degree was controlled to 0.08 MPa. The aqueous solution of tris-hydroxymethyl aminomethane was concentrated under vacuum, and the concentration of the concentrated solution was controlled to 40%.

[0054] The concentrated aqueous solution of tris-hydroxymethyl aminomethane was transferred to a crystallization tank, and the stirring speed was set to 30 rad / min. The temperature of the concentrated solution was lowered to 25°C, and the solution was stirred for 2 h. Then, the temperature of the concentrated solution was lowered to 0°C, the stirring speed was set to 30 rad / min, and seed crystals were added. The solution was stirred at a constant temperature for 8 h.

[0055] The crystallized solution of tris-hydroxymethyl aminomethane was transferred to a centrifuge for drying. The dried product obtained by centrifugation was transferred to a drying oven, and the temperature of the oven was set to 60°C. The product was continuously dried for 24 h, and 473.1 g of the product was collected, with a yield of 47.31%.

[0056] Example 4

[0057] Example 4 differs from Example 1 in that, in Step 2, only the ion-exchanged aqueous solution of tris-hydroxymethyl aminomethane was filtered through a three-stage membrane assembly filter system with 10 μm, 0.45 μm and 0.22 μm membranes in sequence, and the filtration was repeated for 2 h. The other steps were the same. Finally, 542.7 g of the product was collected, with a yield of 54.27%.

[0058] Example 5

[0059] Example 5 differs from Example 1 in that, in Step 3, 0.05 g of DTPA was added to the membrane-filtered aqueous solution of tris-hydroxymethyl aminomethane, and the stirring and heating devices were turned on. The concentration temperature was set to 85°C, and the vacuum degree was controlled to 0.09 MPa. The aqueous solution of tris-hydroxymethyl aminomethane was concentrated under vacuum, and the concentration of the concentrated solution was controlled to 70%. The other steps were the same. Finally, 573.3 g of the product was collected, with a yield of 57.33%.

[0060] Example 6

[0061] Example 6 differs from Example 1 in that step 3 is: 0.5 g of 15-crown-5 is added to the membrane-filtered aqueous solution of tris-hydroxymethyl aminomethane, the stirring and heating device is turned on, the concentration temperature is set to 85°C, the vacuum degree is controlled to 0.09 MPa, and concentration is carried out under vacuum, and the concentration of the concentrated aqueous solution of tris-hydroxymethyl aminomethane is 30%. The other steps are the same. Finally, 260.1 g of product is collected, with a yield of 26.01%.

[0062] Example 7

[0063] Example 7 differs from Example 1 in that step 4 is: the concentrated aqueous solution of tris-hydroxymethyl aminomethane is transferred to a crystallization tank, the stirring speed is set to 50 rad / min, the temperature of the concentrated solution is reduced to 60°C, and the solution is stirred for 2 h, then the temperature of the concentrated solution is reduced to 25°C, the stirring speed is set to 40 rad / min, seed crystals are added, and the solution is stirred at constant temperature for 8 h. The other steps are the same. Finally, 512.5 g of product is collected, with a yield of 51.25%.

[0064] Example 8

[0065] Example 8 differs from Example 1 in that step 2 is: the ion-exchanged aqueous solution of tris-hydroxymethyl aminomethane is sequentially filtered through a three-stage membrane assembly filtration system with pore sizes of 10 μm, 0.45 μm, and 0.22 μm at a constant speed, and the concentrated solution (liquid in the interlayer between the filter core and the filter shell) is removed every 30 min, and the solution is filtered for 10 h. The other steps are the same. Finally, 464.2 g of product is collected, with a yield of 46.42%.

[0066] Example 9

[0067] Example 9 differs from Example 1 in that step 2 is: the ion-exchanged aqueous solution of tris-hydroxymethyl aminomethane is sequentially filtered through a three-stage membrane assembly filtration system with pore sizes of 10 μm, 0.45 μm, and 0.22 μm at a constant speed, and the concentrated solution (liquid in the interlayer between the filter core and the filter shell) is removed every 10 min, and the solution is filtered for 3 h. The other steps are the same. Finally, 481.7 g of product is collected, with a yield of 48.17%.

[0068] Example 10

[0069] 1000 g of tris-hydroxymethyl aminomethane obtained in Example 1 is weighed, 6000 g of ultrapure water is added, and the solution is heated and stirred at 80°C until completely dissolved. After complete dissolution, the solution is transferred to a crystallization tank, the stirring speed is set to 25 rad / min, the temperature of the concentrated solution is reduced to 35°C, and the solution is stirred for 1.5 h, then the temperature of the concentrated solution is reduced to 8°C, the stirring speed is set to 25 rad / min, seed crystals are added, and the solution is stirred at constant temperature for 6 h.

[0070] The crystallized trimethylol aminomethane solution was moved into a centrifuge. The finished product after centrifugation was moved into a drying oven, the drying oven temperature was set to 60°C, continuous drying for 24h, 632.5g of finished product was collected, the yield was 63.25%.

[0071] Example 11

[0072] 1000g of trimethylol aminomethane obtained in Example 1 was weighed, 5000g of ultrapure water was added, heated and stirred at 80°C until completely dissolved, and then transferred to a crystallization cylinder, the stirring speed was set to 15 rad / min, the concentrate temperature was reduced to 25°C, and the stirring was kept for 2h, then the concentrate temperature was reduced to 0°C, the stirring speed was set to 15 rad / min, and the seed crystal was added, and the constant temperature stirring was kept for 4h.

[0073] The crystallized trimethylol aminomethane solution was moved into a centrifuge. The finished product after centrifugation was moved into a drying oven, the drying oven temperature was set to 60°C, continuous drying for 24h, 632.5g of finished product was collected, the yield was 63.25%.

[0074] Example 12

[0075] 1000g of trimethylol aminomethane obtained in Example 1 was weighed, 7000g of ultrapure water was added, heated and stirred at 80°C until completely dissolved, and then transferred to a crystallization cylinder, the stirring speed was set to 30 rad / min, the concentrate temperature was reduced to 50°C, and the stirring was kept for 1h, then the concentrate temperature was reduced to 15°C, the stirring speed was set to 15 rad / min, and the seed crystal was added, and the constant temperature stirring was kept for 8h.

[0076] The crystallized trimethylol aminomethane solution was moved into a centrifuge. The finished product after centrifugation was moved into a drying oven, the drying oven temperature was set to 60°C, continuous drying for 24h, 632.5g of finished product was collected, the yield was 63.25%.

[0077] Comparative Example 1

[0078] Comparative Example 1 and Example 1 differ in that Step 1 is: 1000g of medical grade trimethylol aminomethane was weighed, 6000g of ultrapure water was added, heated and stirred at 80°C until completely dissolved, and then cooled to 25°C in a water bath. 350g of 001*7 cation exchange resin (sodium type) was weighed and loaded into a 500mL HDPE chromatographic column, and then washed with ultrapure water until the pH was 5-6. The obtained trimethylol aminomethane aqueous solution was passed through the regenerated ion exchange column at a flow rate of 50mL / min, and the effluent was collected. The other steps were the same. Finally, 596.1g of finished product was collected, and the yield was 59.61%.

[0079] Comparative Example 2

[0080] Comparative Example 2 differs from Example 1 in that step 4 is: the concentrated aqueous solution of tris-hydroxymethyl aminomethane is transferred to a crystallization tank, the stirring speed is set to 25 rad / min, the temperature of the concentrated solution is reduced to 8°C, seed crystals are added, and constant temperature stirring is performed for 6 h. The other steps are the same. Finally, 567.4 g of finished product is collected, with a yield of 56.74%.

[0081] Comparative Example 3

[0082] Comparative Example 3 differs from Example 1 in that step 2 is: the ion-exchanged aqueous solution of tris-hydroxymethyl aminomethane is sequentially filtered through a three-stage membrane assembly filtration system with 10 μm, 0.45 μm, and 0.22 μm membranes. The other steps are the same. Finally, 536.3 g of finished product is collected, with a yield of 53.63%.

[0083] Comparative Example 4

[0084] Comparative Example 4 differs from Example 1 in that step 2 is: the ion-exchanged aqueous solution of tris-hydroxymethyl aminomethane is filtered through a 0.45 μm membrane. The other steps are the same. Finally, 574.2 g of finished product is collected, with a yield of 57.42%.

[0085] Performance testing

[0086] The raw materials and samples obtained in Examples 1-12 and Comparative Examples 1-4 above were sent for testing. The test results are as follows:

[0087] Table 1: Test results for metal ions in the raw materials and samples of Examples 1-7

[0088]

[0089]

[0090] Table 2: Test results for metal ions in the samples of Examples 8-11 and Comparative Examples 1-4

[0091]

[0092]

[0093] From the above experimental results, it can be seen that the tris-hydroxymethyl aminomethane prepared using the disclosed method can have a content of metal ions of less than 10 ppb, meeting the requirements of G2 grade. Compared with the sample before processing, it can be found that the content of metal ions is greatly reduced. The method is simple and easy to operate, is conducive to industrialized production, and can be used for the preparation of display panels, LED packaging, and middle-end discrete devices.

[0094] The experimental results of Examples 10-12 show that the metal ions of the trimethylol aminomethane treated by the preparation method steps 1-5 and step 6 can be reduced to less than 1 ppb, which can meet the requirements of G3 level and can be used for the preparation of 8-inch and below integrated circuits and TFT-LCDs.

[0095] The specific embodiments are only an explanation of the present application, which is not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A process for the preparation of electronic grade trimethylaminomethane, characterized in that, The method comprises the following steps: Step 1: prepare a solution of trimethylolamine in water, pass the solution through a chromatographic column filled with chelating resin or cation exchange resin which has been pre-treated with ammonia solution; Step 2: circulate the solution of trimethylolamine obtained in step 1 through a three-stage membrane module filtration system; Step 3: add a chelating agent to the solution of trimethylolamine obtained in step 2 to perform chelation and concentration, and remove part of the water; Step 4: perform gradient cooling crystallization on the solution of trimethylolamine obtained in step 3 after chelation and concentration; Step 5: perform centrifugation and drying on the solution of trimethylolamine obtained in step 4 after cooling crystallization to obtain electronic-grade trimethylolamine.

2. The production method according to claim 1, characterized by, In step 1, when preparing the solution of trimethylolamine in water, medical-grade trimethylolamine is used as the raw material and water is ultrapure water. Preferably, the concentration of the prepared solution of trimethylolamine in water is 5-45%.

3. The preparation method according to claim 1, characterized in that, In step 1, the concentration of the ammonia solution is 4-10%. Preferably, in step 1, after treating the chelating resin or cation exchange resin filler of the chromatographic column with ammonia solution, the chromatographic column is washed with pure water until the pH is 7-8.

4. The method of claim 1, wherein, In step 2, when the solution of trimethylolamine passes through the three-stage membrane module filtration system, the concentrated solution in the membrane module is discharged every 10-60 minutes, and the circulation filtration time is 1-10 hours.

5. The preparation method according to claim 1, characterized in that, In step 3, the chelating agent is selected from one or more of EDTA, 15-crown-5, triethylenetetramine and DTPA.

6. The method of claim 1, wherein, In step 3, the amount of the chelating agent added is 0.01-0.1% of the solid mass of trimethylolamine in step 1.

7. The preparation method according to claim 1, characterized in that, In step 3, the concentration of the solution of trimethylolamine after chelation and concentration is 40-65%.

8. The method of claim 1, wherein, In step 4, the specific steps of gradient crystallization are as follows: after the temperature of the concentrated solution is reduced to 25-50°C, the solution is stirred at constant temperature for 1-2 hours; then the temperature of the concentrated solution is reduced to 0-15°C, seed crystals are added, and the solution is stirred at constant temperature for 4-8 hours. Preferably, in step 4, the stirring speed is 15-30 rad / min.

9. The method of claim 1, wherein, In step 5, the drying temperature is 60-90°C, and the drying time is 8-24 hours.

10. The method of any one of claims 1-9, wherein, Further comprising step 6: weigh the electronic-grade trimethylolamine obtained after drying in step 5, prepare a solution of the trimethylolamine in water, perform secondary gradient cooling crystallization, and then perform centrifugation and drying on the solution of trimethylolamine obtained after secondary cooling crystallization to obtain the target product. Preferably, the specific steps of the secondary cooling crystallization are as follows: after the temperature of the solution is reduced to 25-50°C, the solution is stirred at constant temperature for 1-2 hours; then the temperature of the concentrated solution is reduced to 0-15°C, seed crystals are added, and the solution is stirred at constant temperature for 4-8 hours. Preferably, the stirring speed is 15-30 rad / min. Preferably, the drying temperature is 60-90°C, and the drying time is 8-24 hours.

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