Production method of polyphenylmethane polyamine and polymethylene polyphenyl polyisocyanate

Abstract

The invention provides a production method of polyphenyl methane polyamine and polymethylene polyphenyl polyisocyanate. The production method comprises the following steps: (1) sequentially carrying out condensation reaction and isomerization reaction on aniline and formaldehyde, neutralizing reaction liquid, and carrying out phase splitting to obtain an organic phase; (2) aniline is used as an eluent, the organic phase is placed in a packed column of a simulated moving adsorption bed for elution separation, and a fast component containing aniline and diaminodiphenylmethane and a slow component containing polyphenylmethane polyamine and aniline are obtained; (3) repeating the steps on the fast component, and placing the slow component in a stripping tower to separate aniline and water to obtain polyphenylmethane polyamine; a filler of the packed column comprises a polymer containing phosphorous acid groups. The production method of the polyphenylmethane polyamine is designed, the organic phase mixture is separated into diaminodiphenylmethane and the polyphenylmethane polyamine by using the simulated moving adsorption bed, and the separation process is mild in condition, low in energy consumption and suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of production and separation technology of polyphenylmethane polyamines, specifically relating to a production method of polyphenylmethane polyamines and polymethylene polyphenyl polyisocyanate. Background Technology

[0002] Diphenylmethane diisocyanate is one of the main raw materials for the production of polyurethane. Depending on its composition, diphenylmethane diisocyanate can be divided into monomeric diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate. Typically, the preparation method involves the condensation reaction of aniline and formaldehyde to produce a mixture containing diaminodiphenylmethane and polyphenylmethane polyamine. This mixture is then reacted with phosgene to prepare crude diphenylmethane diisocyanate. The crude diphenylmethane diisocyanate is then separated by distillation to obtain monomeric diphenylmethane diisocyanate and polymerized polymethylene polyphenyl polyisocyanate products.

[0003] However, the demand for polymerized polymethylene polyphenyl polyisocyanates is growing compared to monomeric diphenylmethane diisocyanates. Therefore, there is a need to develop methods for producing polymethylene polyphenyl polyisocyanate products with specific functional groups without producing the second product, monomeric diphenylmethane diisocyanate.

[0004] CN118139840A discloses a method for obtaining polymethylene polyphenyl polyisocyanate. The method involves distilling a mixture of diaminodiphenylmethane isomers from a mixture of aniline and formaldehyde condensation reaction, recycling the obtained mixture of diaminodiphenylmethane isomers to a condensation reaction to prepare polyphenylmethane polyamine, and then subjecting the polyphenylmethane polyamine to a phosgenation reaction to produce polymethylene polyphenyl polyisocyanate. The disadvantage of this method is that the separation of diaminodiphenylmethane isomers by distillation requires a high separation temperature, which affects product quality, and the distillation energy consumption is also high.

[0005] Therefore, how to provide a production method for polyphenylmethane polyamines that is energy-efficient, mild, and has adjustable functionality has become an urgent technical problem to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for producing polyphenylmethane polyamines and polymethylene polyphenyl polyisocyanate. The present invention designs a method for producing polyphenylmethane polyamines that utilizes a simulated moving adsorption bed to separate an organic phase mixture into bicyclic diaminodiphenylmethane and polymerized polyphenylmethane polyamines. The separation process is characterized by mild conditions, low energy consumption, and suitability for industrial production.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for producing polyphenylmethane polyamine, the method comprising the following steps:

[0009] (1) Aniline and formaldehyde undergo condensation and isomerization reactions in sequence, the reaction solution is neutralized, and phase separation is performed to obtain an organic phase;

[0010] (2) Using aniline as the eluent, the organic phase is placed in a packed column simulating a moving adsorption bed for elution and separation to obtain a fast component containing aniline and diaminodiphenylmethane, and a slow component containing polyphenylmethane polyamine and aniline.

[0011] (3) Repeat steps (1) and (2) with the fast component containing aniline and diaminodiphenylmethane;

[0012] The slow component containing polyphenylmethane polyamine and aniline is placed in a stripping tower to separate aniline and water, thereby obtaining the polyphenylmethane polyamine;

[0013] The packing material of the packed column comprises a polymer containing phosphorous groups, and the raw materials for preparing the polymer containing phosphorous groups include the following components in parts by weight:

[0014] One part of an alkenyl-containing organic phosphorous acid, 0.5-10 parts of a template molecule, 1-10 parts of a crosslinking agent, 3-25 parts of a porogen, and 0.03-1 part of an initiator;

[0015] The template molecule includes polyphenylmethane polyamine.

[0016] In this invention, a method for producing polyphenylmethane polyamines is designed to separate an organic phase mixture into bicyclic diaminodiphenylmethane and polymerized polyphenylmethane polyamine using a simulated moving adsorption bed. Further, the different adsorption capacities of the polymer containing phosphite groups in the simulated moving adsorption bed column for the bicyclic diaminodiphenylmethane and polymerized polyphenylmethane polyamine, and their different residence times, are utilized to elute and separate them. The polyphenylmethane polyamine is then obtained by stripping, while the separated diaminodiphenylmethane is recycled for condensation and isomerization reactions to improve the yield of polyphenylmethane polyamines. The production method provided by this invention has low energy consumption, mild conditions, and is suitable for industrial production.

[0017] diaminodiphenylmethane ( 4,4-MDA (abbreviated as MDA) has two amino sites. Polyphenylmethane polyamines (p-MDA), taking a tricyclic form as an example... With three amino sites, this invention selects polymers containing phosphite groups as fillers. It was found that diaminodiphenylmethane and polyphenylmethane polyamines have significantly different residence times in the filler, theoretically satisfying the relationship (T...). p-MDA -T0) / (T MDA -T0)=3 / 2(selectivity α) p-MDA / MDA =1.5), because polyphenylmethane polyamines contain many amino sites and have strong adsorption capacity. This invention utilizes the difference in the number of amino groups between the two substances, selecting polymers with specific acidic groups as fillers and specific eluents to achieve their separation.

[0018] In this invention, a polymer containing phosphorous acid groups is selected as the packing material to effectively separate diaminodiphenylmethane and polyphenylmethane polyamine. The phosphorous acid groups in the polymer can form six-membered ring hydrogen bonds with the amino groups in the amino compounds (diaminodiphenylmethane and polyphenylmethane polyamine), resulting in a relatively stable structure that significantly increases the polymer's adsorption capacity for amino compounds. Aniline is used as the eluent. The fast component containing aniline and diaminodiphenylmethane is directly recycled to the condensation reactor for reaction, while the slow component containing aniline and polyphenylmethane polyamine is stripped to obtain polyphenylmethane polyamine that meets the requirements of phosgenation reaction. The schematic diagram of the hydrogen bond structure formed between the polyphenylmethane polyamine and the phosphorous acid groups in the polymer (provided by 4-vinylphenylphosphorous acid) is shown below:

[0019]

[0020] In this invention, the different adsorption capacities of a polymer containing phosphite groups in a simulated moving adsorption bed column for bicyclic diaminodiphenylmethane and polymerized polyphenylmethane polyamine, as well as their different residence times, are utilized to elute and separate the two compounds. The polyphenylmethane polyamine is then obtained by stripping. The production method provided by this invention is energy-efficient, operates under mild conditions, and is suitable for industrial production.

[0021] In this invention, the weight percentage of the template molecule in the raw material for preparing the polymer containing phosphorous groups can be 0.5 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts, etc.

[0022] The weight percentage of the crosslinking agent in the raw materials for preparing the polymer containing phosphite groups can be 1 part, 2 parts, 3 parts, 4 parts, 6 parts, 8 parts, or 10 parts, etc.

[0023] The weight percentage of the porogen in the raw materials for preparing the polymer containing phosphite groups can be 3 parts, 5 parts, 10 parts, 15 parts, 20 parts, or 25 parts, etc.

[0024] The weight percentage of the initiator in the raw materials for preparing the polymer containing phosphite groups can be 0.03 parts, 0.05 parts, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, or 1 part, etc.

[0025] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0026] As a preferred embodiment of the present invention, the organic phosphorous acid having an olefinic group has the structure shown in Formula I:

[0027]

[0028] Wherein, R represents an alkenyl group containing 2 to 20 carbon atoms (e.g., 2, 4, 6, 8, 10, 12, 14, 16, 18 or 20, etc.).

[0029] Preferably, the organic phosphorous acid having an olefinic group is selected from but-3-enylphosphorous acid (…). 2-Pentenylphosphite 4-Vinylphenylphosphite 3-Propylenephenylphosphite Any one or at least two of them.

[0030] As a preferred embodiment of the present invention, the crosslinking agent is selected from any one or a combination of at least two of divinylbenzene, ethylene glycol dimethacrylate, methylenebisacrylamide, trimethoxypropane trimethacrylate, N,N-methylenediacrylamide, N,N-1,4-phenylenediacrylamide, and 3,5-bis(acrylamide)benzoic acid.

[0031] As a preferred embodiment of the present invention, the porogen is selected from any one or a combination of at least two of benzene, toluene, chloroform, dichloromethane, acetonitrile, ethanol, isopropanol, carbon tetrachloride, polyethylene glycol, 1,4-butanediol, and N,N-dimethylformamide (DMF).

[0032] As a preferred embodiment of the present invention, the initiator is selected from any one or a combination of at least two of azobisisobutyronitrile, azobisisoheptanenitrile, methyl ethyl ketone peroxide, cyclohexanone peroxide, and dimethyl azobisisobutyrate.

[0033] As a preferred embodiment of the present invention, the polymer containing phosphorous groups is prepared by the following method, which includes the following steps:

[0034] S1: After mixing the raw material components of the polymer containing phosphorous groups, a polymerization reaction is carried out to obtain a polyphenylmethane polyamine molecularly imprinted polymer.

[0035] S2: After pulverizing the polyphenylmethane polyamine molecularly imprinted polymer, it is eluted to obtain the polymer containing phosphorous acid groups.

[0036] Preferably, the polymerization reaction is carried out in a protective gas-sealed atmosphere, the protective gas including nitrogen.

[0037] Preferably, the polymerization reaction temperature is 70-80℃ (e.g., 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, or 80℃, etc.), and the polymerization reaction time is 20-28h (e.g., 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, or 28h, etc.).

[0038] It should be noted that an ultrasonic deoxygenation step is also included before the polymerization reaction.

[0039] Preferably, the pulverization method includes: soaking the polyphenylmethane polyamine molecularly imprinted polymer in ethanol to harden it, then pulverizing it with a high-speed pulverizer and passing it through a 50-70 mesh sieve (such as 50 mesh, 52 mesh, 54 mesh, 56 mesh, 58 mesh, 60 mesh, 62 mesh, 64 mesh, 66 mesh, 68 mesh or 70 mesh, etc.).

[0040] Preferably, the elution method includes: repeatedly extracting the sample in a Soxhlet extractor with a mixture of ethanol and acetic acid to remove template molecules and porogens, wherein the volume ratio of ethanol to acetic acid is (8-10):1 (e.g., 8:1, 8.2:1, 8.4:1, 8.6:1, 8.8:1, 9:1, 9.2:1, 9.4:1, 9.6:1, 9.8:1, or 10:1, etc.).

[0041] Preferably, the elution process further includes a post-processing step, wherein the post-processing method includes vacuum drying.

[0042] As a preferred embodiment of the present invention, the preparation method of the polymer containing phosphite groups specifically includes the following steps:

[0043] S1: Mix the template molecule, alkenyl organic phosphorous acid and porogen, then add crosslinking agent and initiator, mix evenly, deoxygenate by ultrasonication, purge with nitrogen for 4-7 min, seal, and carry out polymerization reaction at 70-80℃ for 20-28 h to obtain polyphenylmethane polyamine molecularly imprinted polymer.

[0044] S2: The polyphenylmethane polyamine molecularly imprinted polymer was soaked in ethanol to harden it, then pulverized by a high-speed pulverizer and passed through a 50-70 mesh. It was then placed in a Soxhlet extractor and repeatedly extracted with a mixture of ethanol and acetic acid (volume ratio of ethanol to acetic acid (8-10):1) to remove the template molecules and porogen. The degree of removal of polyphenylmethane polyamine was detected by LC. When polyphenylmethane polyamine was basically undetectable, the elution was stopped, and the polymer containing phosphorous acid groups was obtained by vacuum drying.

[0045] As a preferred embodiment of the present invention, the condensation reaction is carried out in the presence of an acidic substance.

[0046] Preferably, the acidic substance includes HCl.

[0047] Preferably, the molar ratio of aniline to formaldehyde is 1:(0.3-0.5), for example, it can be 1:0.3, 1:0.32, 1:0.34, 1:0.36, 1:0.38, 1:0.4, 1:0.42, 1:0.44, 1:0.46, 1:0.48 or 1:0.5, etc.

[0048] Preferably, the molar ratio of aniline to the acidic substance is 1:(0.2-0.5), for example, it can be 1:0.2, 1:0.22, 1:0.24, 1:0.27, 1:0.3, 1:0.33, 1:0.36, 1:0.38, 1:0.41, 1:0.43, 1:0.45, 1:0.46, 1:0.49 or 1:0.5, etc.

[0049] Preferably, the temperature of the condensation reaction is 40-80℃ (e.g., 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃, etc.), and the time is 0.25-2h (e.g., 0.25h, 0.5h, 1h, 1.5h or 2h, etc.).

[0050] Preferably, the temperature of the isomerization reaction is 70-150℃ (e.g., 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃, etc.), and the time is 0.5-3h (e.g., 0.5h, 1h, 1.5h, 2h, 2.5h or 3h, etc.).

[0051] Preferably, the neutralization temperature is 85-130℃ (e.g., it can be 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃ or 130℃, etc.).

[0052] In this invention, the alkaline solution used for neutralization is an aqueous solution of NaOH with a mass concentration of 30-55% (for example, it can be 30%, 33%, 36%, 38%, 40%, 42%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, or 55%).

[0053] As a preferred embodiment of the present invention, the mass ratio of the eluent to the organic phase is (0.5-2):1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, etc.

[0054] In this invention, by controlling the mass ratio of eluent to organic phase within a specific range, a polyphenylmethane polyamine with a suitable degree of polymerization can be obtained, thereby yielding a polymethylene polyphenyl polyisocyanate product with a functionality of 2.2–3. If the mass ratio of eluent to organic phase is too small, i.e., the amount of eluent is too small, the proportion of bicyclic diaminodiphenylmethane in the polyphenylmethane polyamine product increases, resulting in a polymethylene polyphenyl polyisocyanate product with too low functionality. Conversely, if the mass ratio of eluent to organic phase is too large, i.e., the amount of eluent is too large, the proportion of polycyclic polyphenylmethane polyamine in the polyphenylmethane polyamine product increases, resulting in a polymethylene polyphenyl polyisocyanate product with too high functionality.

[0055] Preferably, the elution temperature is 40-70°C, for example, it can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C.

[0056] As a preferred embodiment of the present invention, when the fast component containing aniline and diaminodiphenylmethane is repeated in step (1), the ratio between the sum of the amounts of aniline in step (1) and aniline in the fast component and the amount of diaminodiphenylmethane in the fast component is 1:(0.05-0.5), for example, it can be 1:0.05, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45 or 1:0.5, etc.

[0057] In this invention, by controlling the molar ratio between aniline in step (1) and diaminodiphenylmethane in the slow component within a specific range, a polyphenylmethane polyamine with a suitable degree of polymerization can be obtained, thereby obtaining a polymethylene polyphenyl polyisocyanate product with a functionality of 2.2 to 3. If the molar ratio between aniline in step (1) and diaminodiphenylmethane in the fast component is too small, that is, if the amount of aniline in step (1) is too small, the proportion of polycyclic polyphenylmethane polyamine in the polyphenylmethane polyamine product will increase, and the resulting polymethylene polyphenyl polyisocyanate product will have too high functionality; if the molar ratio between aniline in step (1) and diaminodiphenylmethane in the fast component is too large, that is, if the amount of aniline in step (1) is too large, the proportion of polycyclic polyphenylmethane polyamine in the polyphenylmethane polyamine product will decrease, and the resulting polymethylene polyphenyl polyisocyanate product will have too low functionality.

[0058] It should be noted that when the fast component containing aniline and diaminodiphenylmethane is repeated in step (1), the aniline and diaminodiphenylmethane in the fast component will be mixed with the aniline and formaldehyde in step (1) to obtain a new reactant. The new reactant includes diaminodiphenylmethane, aniline, and formaldehyde, wherein the molar ratio of aniline to diaminodiphenylmethane is 1:(0.05-0.5). If the molar ratio of aniline to diaminodiphenylmethane is too high after the aniline and diaminodiphenylmethane in the fast component are mixed with the aniline and formaldehyde in step (1), that is, the content of aniline is too high, some of the aniline in the fast component can be removed by distillation so that the molar ratio of aniline to diaminodiphenylmethane is 1:(0.05-0.5) when the polycondensation reaction is carried out.

[0059] It should also be noted that when the fast component containing aniline and diaminodiphenylmethane repeats step (1), step (1) is actually: diaminodiphenylmethane, aniline and formaldehyde undergo condensation reaction and isomerization reaction in sequence, neutralize the reaction solution, separate phases to obtain an organic phase, and then proceed to steps (2) and (3) to obtain polyphenylmethane polyamine.

[0060] As a preferred embodiment of the present invention, the method for producing the polyphenylmethane polyamine specifically includes the following steps:

[0061] (1) Aniline, formaldehyde and acidic substances are mixed and subjected to condensation reaction at 40-80℃ for 0.25-2h and isomerization reaction at 70-150℃ for 0.5-3h. Then, an alkaline solution is added and a neutralization reaction is carried out at 85-130℃. After phase separation, an organic phase is obtained.

[0062] (2) Using aniline as the eluent, the organic phase is placed in a packed column simulating a moving adsorption bed and eluted and separated at 40-70℃ to obtain a fast component containing aniline and diaminodiphenylmethane, and a slow component containing polyphenylmethane polyamine and aniline. The mass ratio of eluent to organic phase is (0.5-2):1.

[0063] (3) Repeat steps (1) and (2) with the fast component containing aniline and diaminodiphenylmethane;

[0064] The slow component containing polyphenylmethane polyamine and aniline is placed in a stripping tower to separate aniline and water, thereby obtaining the polyphenylmethane polyamine;

[0065] The molar ratio of aniline to formaldehyde is 1:(0.3-0.5), the molar ratio of aniline to acidic substances is 1:(0.2-0.5), and the molar ratio of aniline to diaminodiphenylmethane is 1:(0.05-0.5). When the fast component containing aniline and diaminodiphenylmethane repeats step (1), the amount of aniline in the above ratios is the sum of the amount of aniline initially added and the amount of aniline in the fast component.

[0066] It should be noted that the present invention does not impose any special restrictions on the number, diameter, or length of the filling columns in the simulated moving adsorption bed. The design can be made according to actual production needs. Examples include, but are not limited to, designing 12 filling columns in the simulated moving adsorption bed, with the filling columns having a diameter of 1 cm and a length of 60 cm.

[0067] It should also be noted that, in this invention, there are no specific requirements for the outlet of the fast component containing aniline and diaminodiphenylmethane, and the slow component containing polyphenylmethane polyamine and aniline, which are separated by the simulated moving adsorption bed. The design should be based on actual production needs and the content of diaminodiphenylmethane and polyphenylmethane polyamine in the mixture at the outlet of each packed column.

[0068] In a second aspect, the present invention provides a polymethylene polyphenyl polyisocyanate, which is obtained by reacting a polyphenylmethane polyamine obtained by the production method described in the first aspect with phosgene (carbonyl chloride, COCl2).

[0069] It should be noted that there are no special restrictions on the process conditions for the reaction of polyphenylmethane polyamines with phosgene in this invention. The temperature, time and post-treatment process commonly used in the art for the reaction of polyphenylmethane polyamines with phosgene are all applicable.

[0070] As a preferred embodiment of the present invention, the functionality of the isocyanate group of the polymethylene polyphenyl polyisocyanate is 2.2-3, for example, it can be 2.2, 2.31, 2.4, 2.53, 2.6, 2.72, 2.83, 2.93 or 3, etc.

[0071] Compared with the prior art, the present invention has the following beneficial effects:

[0072] (1) This invention designs a production method for polyphenylmethane polyamines by using a simulated moving adsorption bed to separate an organic phase mixture into bicyclic diaminodiphenylmethane and polymerized polyphenylmethane polyamine. Further, it utilizes the different adsorption capacities of the polymer containing phosphite groups in the simulated moving adsorption bed column for bicyclic diaminodiphenylmethane and polymerized polyphenylmethane polyamine, and the different residence times of bicyclic diaminodiphenylmethane and polymerized polyphenylmethane polyamine, to elute and separate the bicyclic diaminodiphenylmethane and polymerized polyphenylmethane polyamine. Then, polyphenylmethane polyamine is obtained by stripping, while the separated diaminodiphenylmethane is recycled for condensation and isomerization reactions to improve the yield of polyphenylmethane polyamine, thereby obtaining polymethylene polyphenyl polyisocyanate with a functionality of 2.2-3.

[0073] (2) The production method provided by the present invention has low energy consumption and mild conditions, and is suitable for industrial production. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of the production method of polyphenylmethane polyamine provided in Embodiment 1 of the present invention;

[0075] Figure 2 This is a schematic diagram of the flow of each component in partitions I, II, III, and IV of the simulated moving bed used in Embodiment 1 of the present invention. Detailed Implementation

[0076] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be considered as specific limitations thereof.

[0077] Preparation Examples 1-4

[0078] Preparation Examples 1-4 each provide a polymer containing phosphite groups and a method for preparing the same. The method for preparing the polymer containing phosphite groups is as follows:

[0079] S1: Mix template molecules, alkenyl-containing organic phosphorous acid and porogen, then add crosslinking agent and initiator, mix evenly, deoxygenate by ultrasonication, purge with nitrogen for 5 min, seal, and carry out polymerization reaction at 75℃ for 24 h to obtain polyphenylmethane polyamine molecularly imprinted polymer.

[0080] S2: The polyphenylmethane polyamine molecularly imprinted polymer was soaked in ethanol to harden it, then pulverized by a high-speed pulverizer and passed through a 60-mesh sieve. It was then placed in a Soxhlet extractor and repeatedly extracted with a mixture of ethanol and acetic acid (volume ratio of ethanol to acetic acid 9:1) to remove the template molecules and porogen. The degree of removal of polyphenylmethane polyamine was detected by LC. When polyphenylmethane polyamine was basically undetectable, the elution was stopped, and the polymer containing phosphorous acid groups was obtained by vacuum drying.

[0081] The specific selection and dosage of the alkenyl-containing organic phosphorous acid, template molecule, crosslinking agent, pore-forming agent and initiator are shown in Table 1 below. The polyphenylmethane polyamine is provided by Example 1 of this invention.

[0082] Table 1

[0083]

[0084] Preparation of Comparative Example 1

[0085] This comparative example provides a carboxyl-containing polymer and its preparation method. The only difference from Preparation Example 1 is that 4-vinylphenylphosphine is replaced with an equal mass of methacrylic acid, while the other conditions are the same as in Preparation Example 1.

[0086] Example 1

[0087] This embodiment provides a method for producing polyphenylmethane polyamine, and the process flow diagram of the method is shown below. Figure 1 As shown, its production method is as follows:

[0088] (1) Aniline, a formaldehyde solution with a mass content of 37% (solvent is water) and hydrochloric acid with a mass concentration of 31% were placed in a condensation reactor and mixed. The condensation reaction was carried out at 50°C for 0.5h. Then the resulting reaction solution was placed in an isomerization reactor and the isomerization reaction was carried out at 120°C for 2h. Then the reaction solution obtained by the isomerization reaction was mixed with a NaOH aqueous solution with a mass concentration of 50% to make the pH of the reaction system 10. After the neutralization reaction was carried out at 100°C, the phases were separated to obtain 93g / h organic phase.

[0089] (2) Using aniline as the eluent, the organic phase is placed in a packed column simulating a moving adsorption bed and eluted and separated at 50°C to obtain a fast component containing aniline and diaminodiphenylmethane, and a slow component containing polyphenylmethane polyamine and aniline. The mass ratio of eluent aniline to organic phase is 1:1.

[0090] (3) The fast component containing aniline and diaminodiphenylmethane is recycled into the condensation reactor, and steps (1) and (2) are repeated.

[0091] The slow component containing polyphenylmethane polyamine and aniline was placed in a stripping tower to separate aniline and water, yielding 54.4 g / h of polyphenylmethane polyamine;

[0092] In step (1), the flow rate of aniline is 18.2 g / h, the flow rate of formaldehyde solution is 32.5 g / h, and the flow rate of hydrochloric acid is 38.8 g / h.

[0093] In step (2), the amount of aniline added as eluent is 93 g / h;

[0094] In step (3), the flow rate of aniline in the fast component recycled to the condensation reactor is 74.9 g / h, and the flow rate of diaminodiphenylmethane is 23.3 g / h.

[0095] In step (3), the fast component is recycled into the condensation reactor and mixed with aniline, formaldehyde and hydrochloric acid with a mass concentration of 31% in step (1). The molar ratio of aniline to formaldehyde is 1:0.4, the molar ratio of aniline to HCl is 1:0.3, and the molar ratio of aniline to diaminodiphenylmethane is 1:0.12.

[0096] The simulated moving bed contains 12 packed columns, each 1 cm in diameter and 60 cm long, divided into zones I, II, III, and IV. The ratio of packed columns in zones I, II, III, and IV is 2:4:4:2. The flow diagrams of the components in the simulated moving bed are shown below. Figure 2 As shown, the packing material in the packed column was provided by Preparation Example 1.

[0097] Figure 2 In this simulated moving adsorption bed, based on the positions of the feed and discharge ports, it can be divided into four zones. The feed material enters between zones II and III. In zone III, p-MDA and a small amount of MDA are adsorbed by the adsorbent and carried into zone II. In zone II, the MDA in the adsorbent phase is desorbed by the slow component to improve the purity of p-MDA. The desorbed MDA mixes with the feed material and enters zone III, where the fast component MDA, which is not adsorbed by the adsorbent, is obtained. In zone I, aniline and the circulating liquid in zone IV elute the adsorbent to obtain a high-purity p-MDA slow component. The eluted adsorbent, essentially free of p-MDA, returns to zone IV. In zone IV, the adsorbent adsorbs MDA from the fast component, yielding aniline, essentially free of MDA, which is returned to zone I as the eluent. Here, p-MDA represents polyphenylmethane polyamine, and MDA represents diaminodiphenylmethane.

[0098] Examples 2-13

[0099] Examples 2-13 each provide a method for producing polyphenylmethane polyamine, differing from Example 1 only in that:

[0100] In Examples 2-10: In step (3), the fast component is recycled into the condensation reactor and mixed with aniline, formaldehyde and hydrochloric acid with a mass concentration of 31% in step (1). The molar ratio of aniline to formaldehyde and the molar ratio of aniline to HCl are the same as in Example 1. The molar ratio of aniline to diaminodiphenylmethane and the mass ratio of eluent aniline to organic phase are different from those in Example 1 (see Table 2 below for details). Other conditions are the same as in Example 1.

[0101] In Examples 11-13, the fast component in step (3) is recycled into the condensation reactor and mixed with aniline, formaldehyde and hydrochloric acid with a mass concentration of 31% in step (1). The molar ratios of aniline and formaldehyde, aniline and HCl, and aniline and diaminodiphenylmethane are different. The mass ratio of eluent aniline to organic phase is the same as in Example 1 (see Table 2 below). In Examples 11-13, the polymers containing phosphorous groups provided in Preparation Examples 2-4 are used as packing materials for the packed column in the simulated moving bed. Other conditions are the same as in Example 1.

[0102] It should be noted that if the molar ratio of aniline to formaldehyde in step (1) increases, the proportion of polycyclic polyphenylmethane polyamine in the polyphenylmethane polyamine product decreases, and the functionality of the resulting polymethylene polyphenyl polyisocyanate product decreases; if the molar ratio of aniline to formaldehyde in step (1) decreases, the proportion of polycyclic polyphenylmethane polyamine in the polyphenylmethane polyamine product increases, and the functionality of the resulting polymethylene polyphenyl polyisocyanate product increases.

[0103] If the molar ratio of aniline to HCl in step (1) increases, the proportion of polycyclic polyphenylmethane polyamine in the polyphenylmethane polyamine product increases, and the functionality of the resulting polymethylene polyphenyl polyisocyanate product increases; if the molar ratio of aniline to HCl in step (1) decreases, the proportion of polycyclic polyphenylmethane polyamine in the polyphenylmethane polyamine product decreases, and the functionality of the resulting polymethylene polyphenyl polyisocyanate product decreases.

[0104] Comparative Example 1

[0105] This comparative example provides a method for producing polyphenylmethane polyamine, which differs from Example 1 only in that:

[0106] The carboxyl-containing polymer provided in Comparative Example 1 was used as the packing material for the packed column in the simulated moving bed, and other conditions were the same as in Example 1.

[0107] Application Examples 1-13, Comparative Application Example 1

[0108] Application Examples 1-13 and Comparative Example 1 each provide a polymethylene polyphenyl polyisocyanate, and the preparation method of the polymethylene polyphenyl polyisocyanate is as follows:

[0109] Application Examples 1-13 and Comparative Example 1 were used in sequence. The polyphenylmethane polyamine (50g) provided in Examples 1-13 and Comparative Example 1 was dissolved in chlorobenzene solution to form a chlorobenzene solution with a polyphenylmethane polyamine mass concentration of 35%. This solution was mixed with 200g of phosgene chlorobenzene solution with a mass concentration of 45% and entered into a two-stage phosgenation reaction. The reaction temperature in the first stage was controlled at 75°C and the reaction temperature in the second stage was controlled at 135°C. The reaction time was 2h. After the chlorobenzene was removed from the reaction mixture by distillation, stripping and other separation units, polymethylene polyphenyl polyisocyanate was obtained.

[0110] The functionality of the isocyanate group in polymethylene polyphenyl polyisocyanates was tested using the following method:

[0111] Functionality calculation formula: Functionality = NCO value * number average molecular weight / molar amount of NCO

[0112] Detection methods for each component of the product: Instrument: Agilent 1260 Infinity II gel permeation chromatography (GPC); Column: Shodex GPC KF-802.5; Injection volume: 10 μL; Detector: DAD; Detection wavelength: 210 nm; Mobile phase: tetrahydrofuran; Flow rate: 0.6 mL / min

[0113] The content (A) of each polycyclic isocyanate (p-MDI) was obtained based on the results of gel permeation chromatography.

[0114] Number average molecular weight = A1 * M p-MDI1 +A2*M p-MDI2 +A3*M p-MDI3 +…+A n *M p-MDIn ;

[0115] The method for determining the NCO value uses the di-n-butylamine back titration method. The reaction between di-n-butylamine and NCO groups generates urea, and then excess di-n-butylamine is titrated with a standard hydrochloric acid solution to calculate the content of NCO groups.

[0116] The functionality of the polymethylene polyphenyl polyisocyanates provided in the above application examples is detailed in Table 2 below.

[0117] Table 2

[0118]

[0119] As described above, this invention designs a method for producing polyphenylmethane polyamines. It utilizes a simulated moving adsorption bed to separate an organic phase mixture into bicyclic diaminodiphenylmethane and polymerized polyphenylmethane polyamine. Further, it leverages the different adsorption capacities of the polymer containing phosphite groups in the simulated moving adsorption bed column for the bicyclic diaminodiphenylmethane and polymerized polyphenylmethane polyamine, resulting in different residence times for these two compounds. This allows for the elution and separation of the two compounds, followed by stripping to obtain the polyphenylmethane polyamine. The separated diaminodiphenylmethane is then recycled for condensation and isomerization reactions. The production method provided by this invention features low energy consumption, mild conditions, and suitability for industrial production.

[0120] As can be seen from Examples 1-10 of this application, the present invention further controls the mass ratio of eluent and organic phase, and the molar ratio of aniline and diaminodiphenylmethane within a specific range, to obtain polymethylene polyphenyl polyisocyanate with an isocyanate group functionality of 2.2-3.

[0121] In summary, this invention designs a production method for polyphenylmethane polyamines. It utilizes a simulated moving adsorption bed to separate an organic phase mixture into bicyclic diaminodiphenylmethane and polymerized polyphenylmethane polyamine. Furthermore, it leverages the different adsorption capacities of the polymer containing phosphite groups in the simulated moving adsorption bed column for the bicyclic diaminodiphenylmethane and polymerized polyphenylmethane polyamine, as well as their different residence times. This allows for the elution and separation of the two compounds, followed by stripping to obtain the polyphenylmethane polyamine. The separated diaminodiphenylmethane is then recycled for condensation and isomerization reactions, ultimately yielding a polymethylene polyphenyl polyisocyanate with suitable functionality.

[0122] The applicant declares that the detailed process flow of this invention is illustrated by the above embodiments, but this invention is not limited to the above detailed process flow, that is, it does not mean that this invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A method for producing polyphenylmethane polyamine, characterized in that, The method for producing the polyphenylmethane polyamine includes the following steps: (1) After condensation and isomerization reactions of aniline and formaldehyde, the reaction solution is neutralized and phase separation is performed to obtain an organic phase. (2) Using aniline as the eluent, the organic phase is placed in a packed column simulating a moving adsorption bed for elution and separation to obtain a fast component containing aniline and diaminodiphenylmethane, and a slow component containing polyphenylmethane polyamine and aniline. (3) Repeat steps (1) and (2) with the fast component containing aniline and diaminodiphenylmethane; The slow component containing polyphenylmethane polyamine and aniline is placed in a stripping tower to separate aniline and water, thereby obtaining the polyphenylmethane polyamine; The packing material of the packed column comprises a polymer containing phosphorous groups, and the raw materials for preparing the polymer containing phosphorous groups include the following components in parts by weight: One part of an alkenyl-containing organic phosphorous acid, 0.5-10 parts of a template molecule, 1-10 parts of a crosslinking agent, 3-25 parts of a porogen, and 0.03-1 part of an initiator; The template molecule includes polyphenylmethane polyamine.

2. The method for producing polyphenylmethane polyamine according to claim 1, characterized in that, The organic phosphorous acid with olefin groups has the structure shown in Formula I: Where R represents an alkenyl group containing 2-20 carbon atoms.

3. The method for producing polyphenylmethane polyamine according to claim 2, characterized in that, The organic phosphorous acid with an olefinic group is selected from any one or a combination of at least two of but-3-enylphosphorous acid, 2-pentenylphosphorous acid, 4-vinylphenylphosphorous acid, and 3-propenylphenylphosphorous acid.

4. The method for producing polyphenylmethane polyamine according to claim 1, characterized in that, The crosslinking agent is selected from any one or a combination of at least two of divinylbenzene, ethylene glycol dimethacrylate, methylenebisacrylamide, trimethoxypropane trimethacrylate, N,N-methylenediacrylamide, N,N-1,4-phenylenediacrylamide, and 3,5-bis(acrylamide)benzoic acid. Preferably, the pore-forming agent is selected from any one or a combination of at least two of benzene, toluene, chloroform, dichloromethane, acetonitrile, ethanol, isopropanol, carbon tetrachloride, polyethylene glycol, 1,4-butanediol, and N,N-dimethylformamide.

5. The method for producing polyphenylmethane polyamine according to claim 1, characterized in that, The polymer containing phosphorous groups was prepared by the following method, which includes the following steps: S1: After mixing the raw material components of the polymer containing phosphorous groups, a polymerization reaction is carried out to obtain a polyphenylmethane polyamine molecularly imprinted polymer. S2: After pulverizing the polyphenylmethane polyamine molecularly imprinted polymer, it is eluted to obtain the polymer containing phosphorous acid groups.

6. The method for producing polyphenylmethane polyamine according to claim 1, characterized in that, The condensation reaction is carried out in the presence of an acidic substance; Preferably, the acidic substance includes HCl; Preferably, the molar ratio of aniline to formaldehyde is 1:(0.3-0.5); Preferably, the molar ratio of aniline to acidic substance is 1:(0.2-0.5).

7. The method for producing polyphenylmethane polyamine according to claim 1, characterized in that, The mass ratio of the eluent to the organic phase is (0.5-2):1; Preferably, the elution temperature is 40-70°C.

8. The method for producing polyphenylmethane polyamine according to claim 1, characterized in that, When step (1) is repeated with the fast component containing aniline and diaminodiphenylmethane, the ratio between the sum of the amounts of aniline in step (1) and aniline in the fast component and the amount of diaminodiphenylmethane in the fast component is 1:(0.05-0.5).

9. A polymethylene polyphenyl polyisocyanate, characterized in that, The polymethylene polyphenyl polyisocyanate is obtained by reacting a polyphenylmethane polyamine, which is produced by any one of the production methods described in claims 1-8, with phosgene.

10. The polymethylene polyphenyl polyisocyanate according to claim 9, characterized in that, The isocyanate group of the polymethylene polyphenyl polyisocyanate has a functionality of 2.2-3.

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