Preparation method for diamines and polyamines of the diphenylmethane series

Abstract

A preparation method for diamines and polyamines of the diphenylmethane series. By means of controlling a preparation process for diamines and polyamines of the diphenylmethane series to satisfy that the neutralization phase-separation coefficient M≤1.0, the method can improve the phase separation effect after neutralization while not introducing other substances, thus facilitating stable phase separation, and improving the phase separation efficiency. The preparation method controls the preparation process for the diamines and polyamines of the diphenylmethane series to satisfy that the neutralization phase-separation coefficient M≤1.0, preferably M≤0.8, and more preferably M≤0.5, the neutralization phase-separation coefficient M being calculated according to following equation (I), and R in equation (I) being an aqueous-phase concentration index and being calculated according to following equation (II).

Description

Preparation method of diamines and polyamines of diphenylmethane series Technical Field

[0001] The present invention relates to a preparation technology of diphenylmethane series diamines and polyamines (DAM), and in particular to a preparation method of diphenylmethane series diamines and polyamines. Background Art

[0002] Diamines and polyamines of the diphenylmethane series (DAM) refer to the following types of amines and amine mixtures:

[0003] Here, n represents a natural number ≥ 0. When n = 0, it is called diaminodiphenylmethane, referred to as diamine; when n > 0, it is called polyaminopolyphenylmethane, referred to as polyamine. Mixtures of these two types are referred to as diamines and polyamines of the diaminodiphenylmethane series. The products derived from the replacement of all NH2 groups in DAM with NCO groups are diisocyanates of the diaminodiphenylmethane series, polyisocyanates of the diaminodiphenylmethane series, or polyiminopolyphenylenepolymethylene polyisocyanates, or diisocyanates and polyisocyanates of the diaminodiphenylmethane series (hereinafter referred to as MDI), which are used to produce polyurethane.

[0004] The preparation method of DAM is generally well known in the art and is described in many patents and publications, such as US-A 2009 / 0240077, EP-A-451442, and WO-A-99 / 40059. DAM is prepared by a continuous, semi-continuous, or discontinuous reaction process. Typically, aniline is reacted with hydrochloric acid to form an aniline salt, and then formaldehyde is added to a reactor to form the DAM salt. The crude DAM is obtained through neutralization, water washing, and separation of the organic and inorganic phases. The crude DAM is then purified and phosgenated to produce monomeric or polymeric MDI.

[0005] In traditional large-scale industrial production, the DAM acid salt produced during DAM preparation typically requires neutralization with alkali solution. Following neutralization, the organic and aqueous phases are typically separated in separate containers (i.e., phase separation). The effectiveness of this separation directly impacts the difficulty of post-processing and product quality for both organic and aqueous phases. High levels of water and inorganic salts in the organic phase can lead to high sodium and other content in the resulting DAM, impacting the activity and foaming performance of MDI. High levels of organic components in the aqueous phase can complicate and increase the cost of post-processing the waste brine.

[0006] At present, existing studies at home and abroad have mentioned that, for example, by increasing the amount of acid and alkali used in the DAM production process to increase the driving force of the phase separation process, this method increases the material consumption of preparing DAM, increases the production cost of MDI and the amount of waste brine discharged. EP 2 103 595 A1 relates to phase separation after the neutralization of the crude product, and discloses that phase separation can be assisted by adding water and / or aniline. WO2014 / 173856 reduces the water content in the organic phase containing acetal by using a coalescing aid in the phase separation of the process product obtained in the acetal reaction, thereby also reducing the content of water-soluble impurities. The above method improves the neutralization and phase separation effect to a certain extent, but requires the addition of a coalescing agent or an auxiliary agent, and there is a possibility that the introduction of new substances will affect the quality of the MDI product.

[0007] Summary of the Invention

[0008] The present invention provides a method for preparing diphenylmethane series diamines and polyamines. The method controls the preparation process of the diphenylmethane series diamines and polyamines to satisfy a neutralization phase separation coefficient M≤1.0, thereby improving the phase separation effect after neutralization without introducing other substances, thereby facilitating stable phase separation and improving phase separation efficiency.

[0009] To achieve its purpose, the present invention provides the following technical solutions:

[0010] On one hand, the present invention provides a method for preparing diphenylmethane series diamines and polyamines, comprising reacting aniline, an acidic catalyst and formaldehyde to obtain a reaction solution, neutralizing the reaction solution with an alkali solution and then performing phase separation; in the preparation process of the diphenylmethane series diamines and polyamines, the neutralization phase separation coefficient M is controlled to be ≤1.0, preferably M≤0.8, and more preferably ≤0.5, and the neutralization phase separation coefficient M is calculated by the following formula (I): M=0.881+0.0129lnx1+0.037lnx2+0.2734n1-1.472n2–0.6906R 2 (I)

[0011] R in formula (I) is the water phase concentration index, which is calculated by the following formula (II):

[0012] Wherein, in formula (I) and (II), n1 is the molar ratio of the formaldehyde to the aniline, n2 is the H + The molar ratio of aniline to the aniline;

[0013] In formula (I), x1 is the total mass content of organic impurities in the main raw materials, calculated in ppm; x2 is the total mass content of divalent or higher metal ion impurities in the main raw materials, calculated in ppm; and when x1=0, 0.0129lnx1 in formula (I) is 0; when x2=0, 0.037lnx2 in formula (I) is 0;

[0014] In formula (II), m1 is the total mass content of water in the main raw material, expressed in percentage; c is the OH content in the alkali solution. - With the H in the acid catalyst + The molar ratio of

[0015] The main raw materials are the aniline, the acidic catalyst, the formaldehyde and the alkali solution.

[0016] The organic impurities refer to alcohols, amines and / or ketones with six or fewer ring atoms, excluding aniline, and the ring atoms are carbon atoms. Specifically, the organic impurities mainly include cyclohexylamine, cyclohexanone, cyclohexanol, etc.

[0017] After long-term research, the inventors found that in the process of preparing diphenylmethane series diamines and polyamines, by controlling the amount of the main raw materials, the above-mentioned impurity content in the main raw materials, and the proportion of water in the main raw materials to meet the neutralization phase separation coefficient M≤1.0 calculated by the above formula (I), the smooth separation of the aqueous phase and the organic phase during the neutralization process can be promoted, the phase separation efficiency can be improved, the time required for phase separation can be shortened, and it is beneficial to reduce the amount of inorganic salts entrained in the organic phase obtained after phase separation, for example, the amount of inorganic salts entrained can be made less than 1.0ppm. The present invention does not require a significant adjustment to the preparation process, nor does it require the introduction of new substances. The method of the present invention is used to prepare DAM, which can greatly simplify the refining process of diphenylmethane series diamines and polyamines, reduce the energy consumption required for refining, and help improve the stability of the production process of the device. In some embodiments, the neutralization phase separation coefficient M is 0.001, 0.01, 0.02, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1.0, etc. Preferably, M is controlled to be ≤ 0.8, more preferably ≤ 0.5, which is conducive to further improving the phase separation efficiency after alkali solution neutralization and further reducing the amount of inorganic salt entrainment in the organic phase obtained by phase separation.

[0018] In some embodiments, the total mass content of the organic impurities in the main raw material is, for example, ≤100 ppm, such as 0.05 ppm, 0.5 ppm, 1 ppm, 3 ppm, 10 ppm, 30 ppm, 50 ppm, 80 ppm, 90 ppm or 100 ppm.

[0019] In some embodiments, the total mass content of the divalent or higher metal ion impurities in the main raw material is, for example, ≤10 ppm, such as 0.05 ppm, 0.5 ppm, 1 ppm, 3 ppm, 5 ppm, 8 ppm or 10 ppm.

[0020] The divalent or higher valent metal ion impurities include, for example, one or more divalent or higher valent metal ions of iron, copper, aluminum, chromium, and nickel.

[0021] In some embodiments, the H + The molar ratio of the aniline to the aniline is 0.04-1.0, such as 0.04, 0.05, 0.10, 0.20, 0.30, 0.40 or 0.50, etc., preferably 0.05-0.50.

[0022] The acidic catalyst is, for example, one or more selected from HCl gas, hydrochloric acid, sulfuric acid, phosphoric acid, and methanesulfonic acid, preferably hydrochloric acid, and the mass percentage of HCl in the hydrochloric acid is preferably 10-37%.

[0023] In some embodiments, the molar ratio of the formaldehyde to the aniline is 0.2-0.8, such as 0.2, 0.4, 0.6 or 0.8.

[0024] Preferably, the formaldehyde is fed into the reaction system in the form of gas or aqueous solution. Preferably, the mass concentration of the formaldehyde aqueous solution is 10-55%, such as 10%, 20%, 30%, 40% or 50%.

[0025] In some embodiments, the total mass content of the water in the main raw material is 3-70%, for example, 3%, 5%, 8%, 10%, 15%, 20%, 30%, 40%, 50%, 60% or 70%, etc.

[0026] In some embodiments, the OH in the alkali solution - With the H in the acid catalyst + The molar ratio is 1.05-1.40, such as 1.05, 1.10, 1.20, 1.25, 1.30, 1.35 or 1.40, etc., preferably 1.10-1.30.

[0027] Preferably, the alkaline agent in the alkali solution is a hydroxide of an alkali metal element and / or an alkaline earth metal element, such as sodium hydroxide and / or potassium hydroxide; preferably, the alkali solution is a sodium hydroxide solution, and preferably, the mass concentration of the sodium hydroxide solution is 20-55%, preferably 40-50%.

[0028] In some embodiments, in the process of preparing diphenylmethane series diamines and polyamines, the total mass content of the organic impurities (x1) in the main raw materials is ≤100ppm, the total mass content of the divalent or higher metal ion impurities in the main raw materials (x2) is ≤10ppm, and the H + The molar ratio (n2) of the formaldehyde to the aniline is 0.04-1.0 (preferably 0.05-0.50), the molar ratio (n1) of the formaldehyde to the aniline is 0.2-0.8, the total mass content (m1) of the water in the main raw material is 3-70%, and the OH in the alkali solution is 0. - With the H in the acid catalyst + The molar ratio (c) is 1.05-1.40 (preferably 1.10-1.30), and on this basis, the neutralization phase separation coefficient M is controlled to be ≤1.0.

[0029] In some preferred embodiments, the preparation method specifically comprises the following steps:

[0030] S1: the aniline is contacted with the acidic catalyst to react to obtain an aniline salt;

[0031] S2: contacting the aniline salt obtained in step S1 with formaldehyde to carry out condensation reaction and metathesis reaction to obtain the reaction solution; preferably, the temperature of the condensation reaction is 40-100° C. (e.g., 40° C., 50° C., 60° C., 70° C., 80° C., 90° C., or 100° C., etc.), and the reaction time is, for example, 1-2 hours; preferably, the temperature of the metathesis reaction is 80-150° C. (e.g., 80° C., 90° C., 100° C., 110° C., 120° C., 130° C., 140° C., or 150° C., etc.), preferably 100-140° C., and the reaction time is, for example, 1-5 hours;

[0032] S3: neutralizing the reaction solution obtained in step S2 with the alkali solution, then separating the phases to obtain an organic phase and an aqueous phase, and washing the organic phase with water to obtain a mixture of diamines and polyamines containing the diphenylmethane series;

[0033] S4: Refining the mixture obtained in step S3 to remove aniline and water to obtain a DAM product.

[0034] In some embodiments, in step S4, the aniline and water are removed by resin adsorption and / or distillation, and preferably the distillation is vacuum distillation.

[0035] The present invention also provides a method for improving the phase separation effect after neutralization with alkali solution during the preparation of DAM and / or improving the quality of the DAM product. The DAM is prepared using the preparation method described above. By controlling the neutralization phase separation coefficient M to meet specific requirements, the phase separation effect after neutralization with alkali solution during the preparation of DAM can be improved, thereby facilitating the stable separation of the aqueous phase and the organic phase after alkali solution neutralization and improving the phase separation efficiency. The quality of the DAM product can also be improved, for example, by reducing the amount of inorganic salt entrainment in the DAM product. The details of the method can be referred to the corresponding description of the "Preparation Method of Diphenylmethane Series Diamines and Polyamines" above and will not be repeated here.

[0036] The technical solution provided by the present invention has the following beneficial effects:

[0037] (1) With respect to the preparation process of DAM, the present invention adjusts and controls the operating parameters such as the dosage ratio of the main raw materials, the impurity content, and the water content, so that the entire preparation process satisfies the neutralization phase separation coefficient M≤1.0, thereby achieving stable control of the neutralization process during the DAM production process and facilitating the production of high-quality DAM;

[0038] (2) The method of the present invention is used to prepare DAM. Not only is the method simple to operate and can obtain DAM of satisfactory quality, but it is also conducive to the DAM production process being carried out with lower material and energy consumption, thereby reducing production costs and the amount of waste brine discharged. DETAILED DESCRIPTION

[0039] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The term "and / or" as may be used herein includes any and all combinations of one or more of the associated listed items.

[0041] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. Reagents or instruments used without specifying the manufacturer are all commercially available conventional products.

[0042] Raw materials and sources:

[0043] Aniline: Wanhua Chemical Co., Ltd.

[0044] Formaldehyde: Wanhua Chemical Co., Ltd.

[0045] Hydrochloric acid: Wanhua Chemical Co., Ltd.

[0046] Sodium hydroxide: Wanhua Chemical Co., Ltd.

[0047] In the following Examples and Comparative Examples, the total mass content of organic impurities in the aniline, formaldehyde, hydrochloric acid solution, and aqueous sodium hydroxide solution used refers to the total amount of alcohols, amines, and ketone compounds (excluding aniline) with six or fewer ring atoms, where the ring atoms are carbon atoms. These impurities primarily consist of cyclohexylamine, cyclohexanone, and cyclohexanol. In the following Examples, the divalent or higher metal ions in the aniline, formaldehyde, hydrochloric acid solution, and aqueous sodium hydroxide solution used primarily consist of divalent and trivalent ions of iron, copper, aluminum, chromium, and nickel.

[0048] In the following examples and comparative examples, the mass content of organic impurities in the raw materials was determined by gas chromatography using an Agilent 7890B HP-5 (30 m*0.53 mm*1.5 um) column, an injection port at 280°C, a split ratio of 50:1, an injection volume of 0.5 ul, and a column flow rate of 3 ml / min; a column oven at 50°C for 2 min, then heating at 8°C / min to 80°C for 1 min, then heating at 15°C / min to 290min for 20 min, and an FID detector at 290°C.

[0049] In the following examples and comparative examples, the mass content of divalent or higher metal ions in the raw materials was determined by ICP determination using an Agilent (ICP-OES-725) instrument with a plasma flow rate of 15 L / min, an auxiliary gas flow rate of 1.5 L / min, and an observation height of 10 mm to determine the corresponding wavelengths of different metal elements (e.g., Fe - 238.204 nm, Cu - 327.395 nm).

[0050] In the following examples and comparative examples, the NaCl content in DAM was determined by ion chromatography. 10 g of DAM was diluted with 20 g of dichloromethane and mixed thoroughly. The mixture was then extracted with 10 g of water, and the aqueous phase was analyzed for cations. The instrument was a Metrosep C6 (150 / 4.0) ion chromatograph from Switzerland. The mobile phase consisted of a diluted aqueous solution of dipicolinic acid and nitric acid (0.568 g of dipicolinic acid + 0.223 ml of 68 wt% concentrated nitric acid, diluted to 2 L with pure water). The flow rate was 0.9 ml / min, the temperature was 30°C, and the extraction time was 35 min.

[0051] In the following examples and comparative examples, the calculation formula for the neutralization separation coefficient M is referred to the above formula (I), and the calculation formula for the water phase concentration index R of formula (I) is referred to the above formula (II), which will not be repeated here.

[0052] Example 1:

[0053] Hydrochloric acid solution (mass concentration of 20%) and aniline (mass concentration of 94%) are added into the reactor and mixed to react to generate aniline hydrochloride, wherein the hydrochloric acid (in the form of H + The molar ratio of aniline to formaldehyde was 0.50. A formaldehyde aqueous solution (formaldehyde mass concentration was 37%) was added dropwise to the reaction system, the molar ratio of formaldehyde to aniline was 0.8, and the condensation reaction was carried out at 60°C for 1 hour. Then, the mixture was placed in a transposition kettle and subjected to transposition reaction at 100°C for 2 hours. The obtained transposition liquid was mixed with a 30wt% sodium hydroxide aqueous solution for neutralization. The sodium hydroxide aqueous solution (as OH - with hydrochloric acid (in H + The reaction solution obtained by neutralization was allowed to stand in a phase separator for phase separation, the upper organic phase was taken and washed with pure water, and then water and aniline were removed by vacuum distillation at a pressure of 10 kPaa to obtain refined DAM.

[0054] In this embodiment, in the total mass of aniline, formaldehyde, hydrochloric acid solution and sodium hydroxide aqueous solution used, the total mass content of organic impurities is 5 ppm, the total mass content of divalent or higher metal ions is 1 ppm, and the total mass content of water is 52.8%.

[0055] In this embodiment, the corresponding results of the neutralization phase separation coefficient M, the static phase separation in the phase separator, the time required for phase separation, and the NaCl content in the prepared DAM (determined by ion chromatography) are shown in Table 1.

[0056] Example 2:

[0057] Hydrochloric acid solution (mass concentration of 34%) and aniline (mass concentration of 93.5%) were added into the reactor and mixed to react to generate aniline hydrochloride, wherein the hydrochloric acid (in the form of H + The molar ratio of aniline to formaldehyde was 0.38. A formaldehyde aqueous solution (formaldehyde mass concentration was 30%) was added dropwise to the reaction system, the molar ratio of formaldehyde to aniline was 0.4, and the condensation reaction was carried out at 80°C for 1.5 hours. Then, the solution was placed in a transposition kettle and subjected to transposition reaction at 80°C for 5 hours. The obtained transposition liquid was mixed with a 50wt% sodium hydroxide aqueous solution for neutralization. The sodium hydroxide aqueous solution (as OH - with hydrochloric acid (in H + The reaction solution obtained by neutralization was allowed to stand in a phase separator for phase separation, the upper organic phase was taken and washed with pure water, and then water and aniline were removed by distillation at a pressure of 10 kPaa to obtain refined DAM.

[0058] In this embodiment, in the total mass of aniline, formaldehyde, hydrochloric acid solution and sodium hydroxide aqueous solution used, the total mass content of organic impurities is 15 ppm, the total mass content of divalent or higher metal ions is 2.5 ppm, and the total mass content of water is 36.7%.

[0059] In this embodiment, the corresponding results of the neutralization phase separation coefficient M, the static phase separation in the phase separator, the time required for phase separation, and the NaCl content in the prepared DAM (determined by ion chromatography) are shown in Table 1.

[0060] Example 3:

[0061] HCl gas and aniline (mass concentration 93%) were added to the reactor at a molar ratio of 0.30 to react and generate aniline hydrochloride. Formaldehyde aqueous solution (mass concentration of formaldehyde 55%) was added dropwise to the reaction system, with a molar ratio of formaldehyde to aniline of 0.5. The condensation reaction was carried out at 40°C for 2 hours, and then the mixture was placed in a transposition reactor for transposition reaction at 140°C for 1 hour. The obtained transposition solution was mixed with a 40wt% sodium hydroxide aqueous solution for neutralization. The sodium hydroxide aqueous solution (in the form of OH) - with hydrochloric acid (in H + The reaction solution obtained by neutralization was allowed to stand in a phase separator for phase separation, the upper organic phase was taken and washed with pure water, and then water and aniline were removed by distillation at a pressure of 10 kPaa to obtain refined DAM.

[0062] In this embodiment, in the total mass of aniline, formaldehyde, hydrochloric acid solution and sodium hydroxide aqueous solution used, the total mass content of organic impurities is 30 ppm, the total mass content of divalent or higher metal ions is 4 ppm, and the total mass content of water is 16.1%.

[0063] In this embodiment, the corresponding results of the neutralization phase separation coefficient M, the static phase separation in the phase separator, the time required for phase separation, and the NaCl content in the prepared DAM (determined by ion chromatography) are shown in Table 1.

[0064] Example 4:

[0065] Hydrochloric acid solution (mass concentration of 34%) and aniline (mass concentration of 93%) are added into the reactor and mixed to react to generate aniline hydrochloride, wherein the hydrochloric acid (in the form of H + The molar ratio of the formaldehyde solution to the aniline solution was 0.25. A formaldehyde aqueous solution (formaldehyde mass concentration was 40%) was added dropwise to the reaction system, the formaldehyde to aniline molar ratio was 0.6, and the condensation reaction was carried out at 100°C for 1 hour, and then the solution was put into the transfer kettle for transfer reaction at 120°C for 1 hour. The transfer solution was mixed with a 55wt% sodium hydroxide aqueous solution for neutralization. The sodium hydroxide aqueous solution (as OH -with hydrochloric acid (in H + The reaction solution obtained by neutralization was allowed to stand in a phase separator for phase separation, the upper organic phase was taken and washed with pure water, and then water and aniline were removed by distillation at a pressure of 10 kPaa to obtain refined DAM.

[0066] In this embodiment, in the total mass of aniline, formaldehyde, hydrochloric acid solution and sodium hydroxide aqueous solution used, the total mass content of organic impurities is 50 ppm, the total mass content of divalent or higher metal ions is 6 ppm, and the total mass content of water is 31.6%.

[0067] In this embodiment, the corresponding results of the neutralization phase separation coefficient M, the static phase separation in the phase separator, the time required for phase separation, and the NaCl content in the prepared DAM (determined by ion chromatography) are shown in Table 1.

[0068] Example 5:

[0069] Hydrochloric acid solution (mass concentration of 10%) and aniline (mass concentration of 93%) are added into the reactor and mixed to react to generate aniline hydrochloride, wherein the hydrochloric acid (in the form of H + The molar ratio of aniline to formaldehyde was 0.80. A formaldehyde aqueous solution (formaldehyde mass concentration was 20%) was added dropwise to the reaction system, the molar ratio of formaldehyde to aniline was 0.7, and the condensation reaction was carried out at 60°C for 1 hour. Then, the solution was placed in a transposition reactor and subjected to transposition reaction at 110°C for 2 hours. The obtained transposition solution was mixed with a 32wt% sodium hydroxide aqueous solution for neutralization. The sodium hydroxide aqueous solution (as OH - with hydrochloric acid (in H + The reaction solution obtained by neutralization was allowed to stand in a phase separator for phase separation, the upper organic phase was taken and washed with pure water, and then water and aniline were removed by distillation at a pressure of 10 kPaa to obtain refined DAM.

[0070] In this embodiment, the total mass of aniline, formaldehyde, hydrochloric acid solution and sodium hydroxide aqueous solution used is 80 ppm, the total mass content of organic impurities is 80 ppm, the total mass content of divalent or higher metal ions is 8 ppm, and the total mass content of water is 70.0%.

[0071] In this embodiment, the corresponding results of the neutralization phase separation coefficient M, the static phase separation in the phase separator, the time required for phase separation, and the NaCl content in the prepared DAM (determined by ion chromatography) are shown in Table 1.

[0072] Example 6:

[0073] HCl gas and aniline (mass concentration 93%) were added to the reactor at a molar ratio of 0.04 to react and generate aniline hydrochloride. Gaseous formaldehyde was added dropwise to the reaction system at a molar ratio of formaldehyde to aniline of 0.2. The condensation reaction was carried out at 50°C for 2 hours. The reaction was then placed in a transposition reactor and subjected to a transposition reaction at 150°C for 1 hour. The resulting transposition solution was mixed with a 40wt% sodium hydroxide aqueous solution for neutralization. The sodium hydroxide aqueous solution (in the form of OH) - with hydrochloric acid (in H + The reaction solution obtained by neutralization was allowed to stand in a phase separator for phase separation, the upper organic phase was taken and washed with pure water, and then water and aniline were removed by distillation at a pressure of 10 kPaa to obtain refined DAM.

[0074] In this embodiment, the total mass content of organic impurities in the total mass of aniline, formaldehyde, hydrochloric acid solution and sodium hydroxide aqueous solution used is 100 ppm, the total mass content of divalent or higher metal ions is 10 ppm, and the total mass content of water is 8.8%.

[0075] In this embodiment, the corresponding results of the neutralization phase separation coefficient M, the static phase separation in the phase separator, the time required for phase separation, and the NaCl content in the prepared DAM (determined by ion chromatography) are shown in Table 1.

[0076] Comparative Example 1

[0077] Hydrochloric acid solution (mass concentration of 20%) and aniline (mass concentration of 94%) are added into the reactor and mixed to react to generate aniline hydrochloride, wherein the hydrochloric acid (in the form of H + The molar ratio of aniline to formaldehyde was 0.08. A formaldehyde aqueous solution (formaldehyde mass concentration was 10%) was added dropwise to the reaction system, the molar ratio of formaldehyde to aniline was 0.7, and the condensation reaction was carried out at 60°C for 1 hour. Then, the solution was placed in a transposition reactor and subjected to transposition reaction at 110°C for 2 hours. The obtained transposition solution was mixed with a 20wt% sodium hydroxide aqueous solution for neutralization. The sodium hydroxide aqueous solution (as OH - with hydrochloric acid (in H + The reaction solution obtained by neutralization was allowed to stand in a phase separator for phase separation, the upper organic phase was taken and washed with pure water, and then water and aniline were removed by distillation at a pressure of 10 kPaa to obtain refined DAM.

[0078] In this comparative example, the total mass content of organic impurities in the total mass of aniline, formaldehyde, hydrochloric acid solution and sodium hydroxide aqueous solution used is 60 ppm, the total mass content of divalent or higher metal ions is 5 ppm, and the total mass content of water is 64.8%.

[0079] In this comparative example, the corresponding results of the neutralization phase separation coefficient M, the static phase separation in the phase separator, the time required for phase separation, and the NaCl content in the prepared DAM (determined by ion chromatography) are shown in Table 1.

[0080] Comparative Example 2

[0081] HCl gas and aniline (mass concentration 93%) were added to the reactor at a molar ratio of 0.04 to react and generate aniline hydrochloride. 20wt% formaldehyde aqueous solution was added dropwise to the reaction system, with a molar ratio of formaldehyde to aniline of 0.2. The condensation reaction was carried out at 50°C for 2h, and then the solution was placed in a transposition reactor for transposition reaction at 150°C for 1h. The obtained transposition solution was mixed with a 40wt% sodium hydroxide aqueous solution for neutralization. The sodium hydroxide aqueous solution (in the form of OH) - with hydrochloric acid (in H + The reaction solution obtained by neutralization was allowed to stand in a phase separator for phase separation, the upper organic phase was taken and washed with pure water, and then water and aniline were removed by distillation at a pressure of 10 kPaa to obtain refined DAM.

[0082] In this embodiment, in the total mass of aniline, formaldehyde, hydrochloric acid solution and sodium hydroxide aqueous solution used, the total mass content of organic impurities is 100 ppm, the total mass content of divalent or higher metal ions is 10 ppm, and the total mass content of water is 24.9%.

[0083] In this embodiment, the corresponding results of the neutralization phase separation coefficient M, the static phase separation in the phase separator, the time required for phase separation, and the NaCl content in the prepared DAM (determined by ion chromatography) are shown in Table 1.

[0084] Comparative Example 3

[0085] HCl gas and aniline (mass concentration 93%) were added to the reactor at a molar ratio of 0.04 to react and generate aniline hydrochloride. 20wt% formaldehyde aqueous solution was added dropwise to the reaction system, with a molar ratio of formaldehyde to aniline of 0.2. The condensation reaction was carried out at 50°C for 2h, and then the solution was placed in a transposition reactor for transposition reaction at 150°C for 1h. The obtained transposition solution was mixed with a 40wt% sodium hydroxide aqueous solution for neutralization. The sodium hydroxide aqueous solution (in the form of OH) - with hydrochloric acid (in H + The reaction solution obtained by neutralization was allowed to stand in a phase separator for phase separation, the upper organic phase was taken and washed with pure water, and then water and aniline were removed by distillation at a pressure of 10 kPaa to obtain refined DAM.

[0086] In this embodiment, in the total mass of aniline, formaldehyde, hydrochloric acid solution and sodium hydroxide aqueous solution used, the total mass content of organic impurities is 100 ppm, the total mass content of divalent or higher metal ions is 10 ppm, and the total mass content of water is 24.9%.

[0087] In this embodiment, the corresponding results of the neutralization phase separation coefficient M, the static phase separation in the phase separator, the time required for phase separation, and the NaCl content in the prepared DAM (determined by ion chromatography) are shown in Table 1.

[0088] Comparative Example 4

[0089] HCl gas and aniline (mass concentration 93%) were added to the reactor at a molar ratio of 0.04 to react and generate aniline hydrochloride. 23.2wt% formaldehyde aqueous solution was added dropwise to the reaction system, with a formaldehyde to aniline molar ratio of 0.25, and the condensation reaction was carried out at 50°C for 2h, and then the solution was placed in a transposition reactor for transposition reaction at 150°C for 1h. The obtained transposition solution was mixed with a 40wt% sodium hydroxide aqueous solution for neutralization. The sodium hydroxide aqueous solution (in the form of OH) - with hydrochloric acid (in H + The reaction solution obtained by neutralization was allowed to stand in a phase separator for phase separation, the upper organic phase was taken and washed with pure water, and then water and aniline were removed by distillation at a pressure of 10 kPaa to obtain refined DAM.

[0090] In this embodiment, in the total mass of aniline, formaldehyde, hydrochloric acid solution and sodium hydroxide aqueous solution used, the total mass content of organic impurities is 100 ppm, the total mass content of divalent or higher metal ions is 10 ppm, and the total mass content of water is 24.9%.

[0091] In this embodiment, the corresponding results of the neutralization phase separation coefficient M, the static phase separation in the phase separator, the time required for phase separation, and the NaCl content in the prepared DAM (determined by ion chromatography) are shown in Table 1.

[0092] Table 1 Neutralization phase separation coefficient and effect data of the embodiments and comparative examples

[0093] In Table 1, the neutralization and phase separation time refers to the time required from the reaction liquid obtained by neutralization entering the phase separator for standing to the complete separation of the oil and water phases.

[0094] As can be seen from the above experimental results, the embodiments of the present invention, compared with the comparative example, by controlling the neutralization and phase-splitting coefficient M≤1.0, can significantly shorten the time required for neutralization and phase separation, improve phase separation efficiency, and have a relatively low NaCl content in the product. In the comparative example, there is no control of the neutralization and phase-splitting coefficient M≤1.0, and the resulting neutralization reaction liquid cannot be phase-separated, or requires a longer phase-splitting time. In a preferred embodiment of the present invention, by controlling the neutralization and phase-splitting coefficient M≤0.8, more preferably ≤0.5, can further significantly shorten the time required for phase separation, improve phase separation efficiency, and can further significantly reduce the NaCl content in the product.

[0095] It will be readily understood that the above embodiments are merely examples for clarity of description and are not intended to limit the present invention to these examples. Those skilled in the art will readily appreciate that other variations or modifications based on the above description are possible. It is not necessary and impossible to provide an exhaustive list of all possible implementations. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing diamines and polyamines of the diphenylmethane series, wherein a reaction solution is obtained by reacting aniline, an acidic catalyst and formaldehyde, and the reaction solution is neutralized with an alkali solution and then phase-separated; characterized in that, During the preparation of the diamines and polyamines of the diphenylmethane series, control the neutralization phase separation coefficient M ≤ 1.0, preferably M ≤ 0.8, more preferably ≤ 0.

5. The neutralization phase separation coefficient M is calculated by the following formula (I): M = 0.881 + 0.0129lnx1 + 0.037lnx2 + 0.2734n1 - 1.472n2 – 0.6906R 2 (I) R in formula (I) is the aqueous phase concentration index and is calculated by the following formula (II): Among them, in formulas (I) and (II), n1 is the molar ratio of the formaldehyde to the aniline, and n2 is the molar ratio of the H in the acidic catalyst + to the aniline; In formula (I), x1 is the total mass content of organic impurities in the main raw materials, in ppm; x2 is the total mass content of metal ion impurities with a valence of two or more in the main raw materials, in ppm; and when x1 = 0, the value of 0.0129lnx1 in formula (I) is 0; when x2 = 0, the value of 0.037lnx2 in formula (I) is 0. In formula (II), m1 is the total mass content of water in the main raw material, in percentage; c is the OH in the lye - and the H in the acidic catalyst + molar ratio; The main raw materials refer to the aniline, the acidic catalyst, the formaldehyde, and the alkali solution.

2. The preparation method according to claim 1, characterized in that, The organic impurities refer to alcohols, amines, and / or ketones with the number of ring-forming atoms less than six, and do not include aniline, and the ring-forming atoms are carbon atoms. The total mass content of the organic impurities in the main raw materials is, for example, ≤100 ppm.

3. The preparation method according to claim 1 or 2, characterized in that, The total mass content of the metal ion impurities with a valence of two or more in the main raw materials is, for example, ≤10 ppm. The metal ion impurities with a valence of two or more include, for example, one or more of divalent and above metal ions of iron, copper, aluminum, chromium, and nickel.

4. The preparation method according to any one of claims 1-3, characterized in that, The H in the acidic catalyst + and the aniline have a molar ratio of 0.04 - 1.0, preferably 0.05 - 0.50; The acidic catalyst is, for example, selected from one or more of HCl gas, hydrochloric acid, sulfuric acid, phosphoric acid, and methanesulfonic acid, preferably hydrochloric acid, and preferably the mass percentage content of HCl in hydrochloric acid is 10-37%.

5. The preparation method according to any one of claims 1-4, characterized in that, The molar ratio of the formaldehyde to the aniline is 0.2-0.

8. Preferably, the formaldehyde is fed into the reaction system in a gaseous phase or an aqueous solution form, and preferably the mass concentration of the formaldehyde aqueous solution is 10-55%.

6. The preparation method according to any one of claims 1-5, characterized in that, The total mass content of water in the main raw materials is 3-70%.

7. The preparation method according to any one of claims 1-6, characterized in that, OH in the lye - and H in the acidic catalyst + have a molar ratio of 1.05 - 1.40, preferably 1.10 - 1.30; Preferably, the basic reagent in the alkali solution is a hydroxide of an alkali metal element and / or an alkaline earth metal element, such as sodium hydroxide and / or potassium hydroxide; preferably the alkali solution is a sodium hydroxide solution, preferably the mass concentration of the sodium hydroxide solution is 20-55%, preferably 40-50%.

8. The preparation method according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: S1: The aniline reacts with the acidic catalyst to obtain an aniline salt. S2: The aniline salt obtained in step S1 is contacted with the formaldehyde for a condensation reaction and a rearrangement reaction to obtain the reaction solution; preferably the temperature of the condensation reaction is 40-100 °C, and the reaction time is, for example, 1-2 hours; preferably the temperature of the rearrangement reaction is 80-150 °C, preferably 100-140 °C, and the reaction time is, for example, 1-5 h. S3: The reaction solution obtained in step S2 is neutralized with the alkali solution, and then phase separation is carried out to obtain an organic phase and an aqueous phase, and the organic phase is washed with water to obtain a mixture containing the diamine and polyamine of the diphenylmethane series. S4: The mixture obtained in step S3 is refined, and after removing aniline and water, a DAM product is obtained.

9. The preparation method according to claim 8, characterized in that, In step S4, the aniline and water are removed by means of resin adsorption and / or distillation, and preferably the distillation is vacuum distillation.

10. A method for improving the phase separation effect after neutralization with an alkali solution during the DAM preparation process and / or improving the quality of the DAM product, characterized in that, The DAM is prepared by using the preparation method according to any one of claims 1-9.

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