Method for separating polybenzimidazole from reaction liquid containing polybenzimidazole

Abstract

The invention relates to the technical field of polybenzimidazole, and discloses a method for separating polybenzimidazole from a polybenzimidazole-containing reaction solution, which comprises the following steps: (1) feeding the polybenzimidazole-containing reaction solution obtained by solution polymerization into a treatment device in which an extracting solution is preset, the paddle of the stirring paddle is in a blade shape; the stirring speed of the treatment device is controlled to be 50 to 1000 rpm, preferably 80 to 200 rpm; and (2) carrying out solid-liquid separation on the product obtained in the step (1) to obtain a solid phase (a polybenzimidazole crude product) and a liquid phase, and collecting the solid phase. By adopting the method to treat the reaction liquid containing polybenzimidazole, the solubility of the polybenzimidazole product can be improved, and the processability of the polybenzimidazole product can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of polybenzimidazole, in particular to a method for separating polybenzimidazole from a reaction solution containing the polybenzimidazole. Background Art

[0002] Polybenzimidazole (PBI) is a type of aromatic heterocyclic polymer containing repeating structural units of benzimidazole in the main chain. Polybenzimidazole is a special engineering plastic with excellent comprehensive performance. It has excellent high temperature resistance, chemical stability and mechanical properties. It is widely used in aerospace, fire retardant, semiconductor, high temperature fuel cell, gas separation and other fields. There are two main methods for synthesizing polybenzimidazole materials: melt polymerization and solution polymerization. The molecular weight of the melt polymerization product is relatively low, and side reactions are prone to form gels, resulting in poor product solubility and difficulty in subsequent processing. The solution polymerization product has less gel content and higher molecular weight, which is conducive to expanding its application range. At present, the industrial production of polybenzimidazole materials adopts melt polymerization, while solution polymerization is mainly concentrated in the laboratory stage. There are few implementation technologies for industrial post-processing of polybenzimidazole solution polymerization.

[0003] The solution polymerization of polybenzimidazole requires an acidic solvent. After the polymerization, the solvent is difficult to wash away due to the high viscosity of the solution. In addition, due to the high polymerization temperature, the product is prone to high-temperature bonding when washing, and the product solidifies into large solids in the extract, so that the solvent and the extract are wrapped in the product, increasing the difficulty of subsequent neutralization and cleaning processes. The resulting product has poor solubility, which has an adverse effect on the subsequent processing and molding of polybenzimidazole. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem of poor processing performance of polybenzimidazole products produced by solution polymerization and to provide a method for separating polybenzimidazole from a reaction solution containing polybenzimidazole.

[0005] In order to achieve the above-mentioned purpose, the inventors have improved the separation process of polybenzimidazole, installed a stirring paddle with controllable speed in the processing device, and set the blade of the stirring paddle as a blade, so that the reaction liquid containing polybenzimidazole enters the extracting liquid and is initially crushed during the stirring process, so that the polybenzimidazole is precipitated from the reaction liquid in time, thereby improving the solubility of the polybenzimidazole. Therefore, the present invention provides a method for separating polybenzimidazole from a reaction liquid containing polybenzimidazole, and the method comprises the following steps:

[0006] (1) feeding the reaction solution containing polybenzimidazole obtained by solution polymerization into a treatment device pre-filled with an extracting solution, wherein the treatment device is provided with a stirring paddle, wherein the paddle shape of the stirring paddle is a blade shape; controlling the stirring speed of the treatment device to be 50-1000 rpm, preferably 80-200 rpm;

[0007] (2) subjecting the product obtained in step (1) to solid-liquid separation to obtain a solid phase (crude polybenzimidazole product) and a liquid phase, and collecting the solid phase.

[0008] The method of the present invention is used to treat the reaction solution containing polybenzimidazole, which can improve the solubility of the polybenzimidazole product and the processing performance of the polybenzimidazole product. The method of the present invention can also shorten the time of post-treatment (washing and water washing). DETAILED DESCRIPTION

[0009] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0010] The present invention provides a method for separating polybenzimidazole from a reaction solution containing polybenzimidazole, the method comprising the following steps:

[0011] (1) feeding the reaction solution containing polybenzimidazole obtained by solution polymerization into a treatment device pre-filled with an extracting solution, wherein the treatment device is provided with a stirring paddle, wherein the paddle shape of the stirring paddle is a blade shape; controlling the stirring speed of the treatment device to be 50-1000 rpm, preferably 80-200 rpm;

[0012] (2) subjecting the product obtained in step (1) to solid-liquid separation to obtain a solid phase and a liquid phase, and collecting the solid phase.

[0013] In the present invention, the stirring speed of the processing device can be 50rpm, 80rpm, 100rpm, 120rpm, 130rpm, 140rpm, 150rpm, 160rpm, 180rpm, 200rpm, 300rpm, 400rpm, 500rpm, 700rpm, 800rpm, 1000rpm, and a range consisting of any two of the above points.

[0014] In the present invention, the paddle shape of the stirring paddle in the treatment device is set to be blade-shaped. In order to further improve the treatment effect, increase the solubility of the polymer product, and reduce the content of the solvent and extract in the polymer product, preferably, the polymer is initially crushed in the extract to better remove the residual solvent wrapped in the solid.

[0015] In the present invention, the processing device may be a post-processor with a stirring paddle commonly used in the art, such as a processing kettle or a precipitation kettle.

[0016] According to the present invention, the polybenzimidazole-containing reaction solution can be a product prepared by a solution polymerization method in the art. Preferably, the content of polybenzimidazole in the polybenzimidazole-containing reaction solution is 1-20 wt % (for example, 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 12 wt %, 14 wt %, 16 wt %, 18 wt %, 20 wt %, and a range consisting of any two of the above), preferably 5-10 wt %.

[0017] According to the present invention, preferably, the reaction solution containing polybenzimidazole contains a solvent, and the solvent is preferably one or more of a mixed solution of methanesulfonic acid and phosphorus pentoxide, polyphosphoric acid, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, etc.

[0018] According to the present invention, preferably, the solubility of polybenzimidazole in the extract is less than 0.01g; more preferably, the extract is water and / or an alkaline aqueous solution. The alkaline aqueous solution can be selected from at least one of an aqueous solution of an alkali metal hydroxide, an aqueous solution of an alkali metal carbonate, an aqueous solution of an alkali metal bicarbonate, and ammonia water. The alkaline aqueous solution can be selected from at least one of an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an aqueous sodium carbonate solution, an aqueous potassium carbonate solution, an aqueous sodium bicarbonate solution, and ammonia water. The mass fraction of the alkaline aqueous solution can be 0.1-60wt% (for example, 0.1wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 15wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, and the range composed of any two of the above points).

[0019] According to the present invention, preferably, the temperature of the extract is 0-30°C; more preferably, the temperature of the extract is 0-25°C. In the present invention, the temperature of the extract can be 0°C, 0.5°C, 1°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, and a range consisting of any two of the above points.

[0020] According to the present invention, preferably, the weight of the extracting solution pre-set in the treatment device is 1-10kg (e.g., 1kg, 2kg, 3kg, 4kg, 5kg, 6kg, 7kg, 8kg, 9kg, 10kg, and a range consisting of any two of the above) per kilogram of the reaction solution containing polybenzimidazole, and more preferably 1-5kg. Too much pre-set extracting solution will cause waste of extracting solution and produce too much waste water; too little will reduce the washing effect of the residual solvent. Limiting it within the above range can reduce the amount of extracting solution while ensuring the washing effect.

[0021] In the present invention, the weight ratio of the extract to the reaction solution containing polybenzimidazole can be 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, and a range consisting of any two of the above points.

[0022] According to the present invention, in order to remove the solvent adsorbed on the surface of the solid phase obtained in step (2), the solid phase can be washed. Therefore, the method can also include washing the solid phase with water and / or an alkaline solution, and the washing conditions make the pH value of the washing liquid after the alkaline solution and the solid washing 7-9 (preferably 7-8). More preferably, during the washing process, the amount of water used is 1-30kg, preferably 1-10kg, per kilogram of the reaction solution containing polybenzimidazole.

[0023] According to the present invention, preferably, the alkaline solution is selected from at least one of an aqueous solution of an alkali metal hydroxide, an aqueous solution of an alkali metal carbonate, an aqueous solution of an alkali metal bicarbonate, and ammonia. The alkaline solution may be selected from at least one of an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an aqueous sodium carbonate solution, an aqueous potassium carbonate solution, an aqueous sodium bicarbonate solution, and ammonia. The mass fraction of the alkaline aqueous solution may be 0.1-60wt% (e.g., 0.1wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 15wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, and the range of any two of the above).

[0024] In the present invention, when washing with water and / or alkali solution, it can be carried out in multiple times. For example, the water and / or alkali solution can be divided into 2-3 parts and the solid phase can be washed in 2-3 times.

[0025] According to the present invention, in order to more fully remove the residual solvent, preferably, the method further comprises pulverizing the washed solid phase. The pulverization can be carried out by a pulverization method commonly used in the art.

[0026] According to the present invention, preferably, the method further comprises washing the crushed solid phase with water; preferably, during the washing process, the amount of water used is 1-10 kg per kilogram of the reaction liquid containing polybenzimidazole. In the present invention, the washing process can be carried out in multiple times, for example, the water is divided into 2-3 parts, and the crushed solid phase is washed with water in multiple times.

[0027] According to the present invention, preferably, the method further comprises drying the washed solid phase, and the drying conditions include: temperature of 60-120° C. and time of 1-24 h.

[0028] In the present invention, the water used in the washing or water-washing process of the solid phase is tap water and / or deionized water. Unless otherwise specified, the water used is tap water.

[0029] In the present invention, preferably, the polybenzimidazole-containing reaction solution is obtained by reacting an aromatic component containing at least four amino groups with an aromatic or aliphatic component containing at least two carboxyl groups in an inert gas atmosphere at 100-220° C. for 0.5-72 h under solution polymerization conditions to obtain the polybenzimidazole reaction solution.

[0030] According to the present invention, preferably, the solvent used in the solution polymerization process is a mixed solvent of phosphorus pentoxide and methanesulfonic acid and / or polyphosphoric acid; more preferably, the weight ratio of methanesulfonic acid to phosphorus pentoxide is 10-50:1.

[0031] According to the present invention, preferably, the total amount of the aromatic component containing at least four amino groups and the aromatic or aliphatic component containing at least two carboxyl groups is 1-160 mmol, more preferably 1.5-60 mmol, per 100 g of the solvent.

[0032] According to the present invention, preferably, the aromatic hydrocarbon component containing at least four amino groups is an aromatic hydrocarbon tetraamine; more preferably, the aromatic hydrocarbon tetraamine contains no less than 1 benzene ring; further preferably, the aromatic hydrocarbon tetraamine is selected from one or more of the following structures:

[0033]

[0034] Wherein, X is selected from oxygen atom, sulfur atom, carbonyl group, sulfonyl group, substituted or unsubstituted alkyl group, for example, -O-, -S-,

[0035] According to the present invention, preferably, the aromatic or aliphatic component containing at least two carboxyl groups has a structure shown in formula (1):

[0036] HOOC-R-COOH Formula (1)

[0037] Wherein, R is selected from an aromatic hydrocarbon ring, an aromatic heterocyclic ring or a hydrocarbon group (e.g., a chain alkane group, a cycloalkane group, an alkene group, etc.); the number of carbon atoms in the structure shown in formula (1) is 6-22;

[0038] More preferably, the aromatic or aliphatic component containing at least two carboxyl groups is selected from one or more of the following structures:

[0039]

[0040] Among them, n=4-8.

[0041] According to the present invention, preferably, the molar ratio of the aromatic component containing at least four amino groups to the aromatic or aliphatic component containing at least two carboxyl groups is 1:0.6-2; preferably 1:0.7-1.5.

[0042] The present invention will be described in detail below by way of examples. In the following examples,

[0043] The raw materials used are all commercially available.

[0044] Preparation Example 1

[0045] Equimolar (0.4 mol) amounts of 3,3'-diaminobenzidine and isophthalic acid were added to polyphosphoric acid (1.5 kg), and the mixture was reacted at 220° C. in a nitrogen atmosphere for 6 h to obtain 1.6 kg of a polybenzimidazole reaction solution, wherein the content of polybenzimidazole in the reaction solution was about 7% by weight.

[0046] Example 1

[0047] The reaction solution containing polybenzimidazole obtained in Preparation Example 1 was separated

[0048] (1) The reaction solution containing polybenzimidazole obtained in Preparation Example 1 was immediately introduced into a treatment kettle filled with water (the water temperature was 25° C. and the amount of water was 3.2 kg). The treatment kettle was equipped with a stirring paddle, and the paddle shape of the stirring paddle was blade-shaped. During the introduction of the reaction solution, the stirring speed of the stirring paddle was controlled to be 80 rpm. The polymer in the reaction solution was precipitated in the water in a linear form and was broken up.

[0049] (2) The product obtained in step (1) is subjected to solid-liquid separation to obtain a solid phase and a liquid phase, water (2 times, total water volume 3.2 kg) is added to the solid phase to wash the solid phase, and a 20 wt% potassium carbonate aqueous solution is added to the washed solid phase to neutralize the washing liquid to pH = 7-8. The washed solid phase is crushed to obtain a powder, 3.2 kg of water is added to the powder to wash it to neutrality, and it is dried at 80°C for 24 hours. The dried product (100 g) is sent for product packaging.

[0050] Example 2

[0051] The method of Example 1 was followed, except that the temperature of the water in the treatment kettle was 5° C. and the stirring speed of the stirring paddle of the treatment kettle was 100 rpm.

[0052] Example 3

[0053] The reaction solution containing polybenzimidazole obtained in Preparation Example 1 was separated

[0054] (1) The reaction solution containing polybenzimidazole obtained in Preparation Example 1 was immediately introduced into a treatment kettle filled with water (water temperature was 15° C., water amount was 2.4 kg), the treatment kettle was equipped with a stirring paddle, the paddle shape of the stirring paddle was blade-shaped, and the stirring speed of the stirring paddle was controlled to be 120 rpm during the introduction of the reaction solution. The polymer in the reaction solution was precipitated in the water in a linear form and was broken up.

[0055] (2) The product obtained in step (1) is subjected to solid-liquid separation to obtain a solid phase and a liquid phase, 2.4 kg of water is added to the solid phase to wash the solid phase, 5 wt% potassium carbonate aqueous solution is added to the washed solid phase to neutralize the washing liquid to pH = 7-8, the washed solid phase is crushed to obtain a powder, 2.4 kg of water is added to the powder to wash it to neutrality, and it is dried at 80° C. for 24 hours. The dried product is sent for product packaging.

[0056] Example 4

[0057] The reaction solution containing polybenzimidazole obtained in Preparation Example 1 was separated

[0058] (1) The reaction solution containing polybenzimidazole obtained in Preparation Example 1 is immediately introduced into a treatment kettle filled with water (the water temperature is 20° C. and the amount of water is 2 kg). The treatment kettle is equipped with a stirring paddle, and the paddle shape of the stirring paddle is blade-shaped. During the introduction of the reaction solution, the stirring speed of the stirring paddle is controlled to be 140 rpm. The polymer in the reaction solution is precipitated in the water in a linear form and is broken up.

[0059] (2) The product obtained in step (1) is subjected to solid-liquid separation to obtain a solid phase and a liquid phase, 2 kg of water is added to the solid phase to wash the solid phase, 10 wt% sodium carbonate aqueous solution is added to the washed solid phase to neutralize the washing liquid to pH = 7-8, and the washed solid phase is crushed to obtain a powder. 2 kg of water is added to the powder to wash it until it is neutral, and it is dried at 80°C for 24 hours. The dried product is sent for product packaging.

[0060] Comparative Example 1

[0061] The method of Example 1 was followed, except that a stirring paddle was provided in the processing kettle, no blades were installed on the paddles of the stirring paddle, and the stirring speed of the stirring paddle of the processing kettle was 40 rpm.

[0062] Test Example 1

[0063] (1) The insoluble content of the products separated from the examples and comparative examples was tested by the following method: 0.2 g of PBI powder was added with 6 g of anhydrous dimethyl sulfoxide (DMSO), and the solution was dissolved at 80° C. for 3 hours under stirring and heating conditions to obtain a dissolved product. The dissolved product was filtered using a filter paper with a pore size of 30 to 50 μm using a water pump to collect the insoluble residue. The residue was washed and dried, and the mass of the residue was weighed to calculate the mass fraction of the residue in the PBI powder. The test results are shown in Table 1.

[0064] Table 1

[0065] Insoluble matter content (wt%) Example 1 2.1 Example 2 0.5 Example 3 0.3 Example 4 0.8 Comparative Example 1 13.8

[0066] It can be seen from the results in Table 1 that the content of insoluble matter in the polybenzimidazoles of Examples 1-4 is lower than that in Comparative Example 1. Particularly preferably, the content of insoluble matter in the polybenzimidazoles of Examples 2-4 is even lower.

[0067] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for separating polybenzimidazole from a reaction solution containing polybenzimidazole, It is characterized in that The method comprises the following steps: (1) feeding the reaction solution containing polybenzimidazole obtained by solution polymerization into a treatment device pre-filled with an extracting solution, wherein the treatment device is provided with a stirring paddle, wherein the paddle shape of the stirring paddle is a blade shape; controlling the stirring speed of the treatment device to be 50-1000 rpm, preferably 80-200 rpm; (2) subjecting the product obtained in step (1) to solid-liquid separation to obtain a solid phase and a liquid phase, and collecting the solid phase.

2. The method according to claim 1, in, The content of polybenzimidazole in the polybenzimidazole-containing reaction solution is 1-20% by weight, preferably 5-10% by weight.

3. The method according to claim 1, in, The reaction solution containing polybenzimidazole contains a solvent, and the solvent is selected from at least one of a mixed solution of methanesulfonic acid and phosphorus pentoxide, polyphosphoric acid, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

4. The method according to claim 1, in, The solubility of polybenzimidazole in the extract is less than 0.01 g; Preferably, the extract is water and / or an alkaline aqueous solution.

5. The method according to claim 1, in, The temperature of the extract is 0-30°C.

6. The method according to claim 1, in, The weight of the extracting solution pre-placed in the treatment device is 1-10 kg, preferably 1-5 kg, per kilogram of the reaction solution containing polybenzimidazole.

7. The method according to any one of claims 1 to 7, in, The method further comprises washing the solid phase with water and / or an alkaline solution, wherein the washing conditions make the pH value of the mixture of the alkaline solution and the solid be 7-9.

8. The method according to claim 7, in, The method further comprises pulverizing the washed solid phase.

9. The method according to claim 8, in, The method further comprises washing the crushed solid phase with water.

10. The method according to claim 9, in, The method further comprises drying the washed solid phase, wherein the drying conditions include: a temperature of 60-120° C. and a time of 1-24 hours.

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