Method for shortening preparation period of polybenzimidazole

Abstract

The invention relates to the technical field of polybenzimidazole, and discloses a method for shortening the preparation period of polybenzimidazole, which comprises the following steps: (1) under the atmosphere that the oxygen content is not higher than 20ppm, carrying out polymerization reaction on a monomer in a first reactor filled with a solvent to obtain a reaction liquid; (2) feeding the reaction liquid obtained in the step (1) into a second reactor, and continuously carrying out polymerization reaction in the atmosphere with the oxygen content not higher than 20ppm; wherein the set temperature of the second reactor is 10-60 DEG C higher than that of the first reactor. According to the invention, polybenzimidazole is prepared by adopting a method of segmented temperature control polymerization of two reactors, so that the retention time of materials in the reactors is shortened, the production cycle of products is further shortened, the utilization rate of equipment is improved, and the annual output of polybenzimidazole is improved.

Description

Technical Field

[0001] The invention relates to the technical field of polybenzimidazole, and in particular to a method for shortening the preparation cycle of polybenzimidazole. Background Art

[0002] Polybenzimidazole is a type of high molecular polymer containing benzimidazole groups in the repeating unit, and is also a type of special engineering plastic with excellent performance. It has excellent high temperature resistance, corrosion resistance, high mechanical strength, high hardness, and high wear resistance. It can be used in extremely high temperature, harsh chemical and plasma environments. It is currently widely used in high temperature proton exchange membranes, heat-resistant fibers, cut-resistant fibers, gas-liquid separation, fire retardant and aerospace fields. There are four main methods for the synthesis of polybenzimidazole: parent method, nucleophilic substitution method, melt polymerization method and solution polymerization method. However, the parent method and nucleophilic substitution method are limited by harsh experimental conditions, which limits their wide range of applications. The commonly used methods are melt polymerization method and solution polymerization method.

[0003] Compared with the melt polymerization method, the solution polymerization method has the advantages of mild reaction conditions, low energy consumption (low reaction temperature), green byproducts (the byproduct of solution polymerization is water, while the byproducts of melt polymerization are mostly toxic substances such as phenol), etc., and has broad industrial application value. However, the long reaction time and low polymerization efficiency of the solution polymerization method for preparing polybenzimidazole have seriously affected the industrial production of polybenzimidazole. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of low polybenzimidazole solution polymerization efficiency and long production cycle in the prior art and to provide a method for shortening the polybenzimidazole preparation cycle.

[0005] In order to achieve the above object, the present invention provides a method for shortening the preparation cycle of polybenzimidazole, which comprises the following steps:

[0006] (1) in an atmosphere having an oxygen content of not more than 20 ppm, subjecting the monomer to a polymerization reaction in a first reactor containing a solvent to obtain a reaction solution;

[0007] (2) feeding the reaction solution obtained in step (1) into a second reactor to continue the polymerization reaction in an atmosphere with an oxygen content of not more than 20 ppm;

[0008] The set temperature of the second reactor is 10-60° C. higher than the set temperature of the first reactor.

[0009] The invention adopts two reactors to prepare polybenzimidazole by staged temperature-controlled polymerization, thereby shortening the residence time of materials in the reactors, thereby shortening the production cycle of the product, improving equipment utilization, and increasing the annual output of polybenzimidazole.

[0010] The preferred embodiment of the present invention can further shorten the production cycle of polybenzimidazole by adding a dissolving tank or arranging reaction tanks in series and / or in parallel in the reactor.

[0011] The method of the invention can prepare polybenzimidazoles with different molecular weights to meet the diversified market demands. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The H-NMR spectra of the polybenzimidazole obtained in Example 1 (represented by A) and Comparative Example 1 (represented by B);

[0013] Figure 2 The thermogravimetric analysis spectra of the polybenzimidazole obtained in Example 1 (represented by A) and Comparative Example 1 (represented by B);

[0014] Figure 3 ] are infrared spectra of the polybenzimidazoles obtained in Example 1 (denoted by A) and Comparative Example 1 (denoted by B). DETAILED DESCRIPTION

[0015] 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.

[0016] In the present invention, the "aromatic hydrocarbon component containing at least four amino groups" is referred to as "tetramine" for short; the "aromatic hydrocarbon or aliphatic component containing at least two carboxyl groups" is referred to as "diacid" for short.

[0017] The "first", "second" and "third" mentioned in the present invention do not limit the technical solution of the present invention, but are only used to distinguish the reactors in different stages.

[0018] The present invention provides a method for shortening the preparation cycle of polybenzimidazole, which comprises the following steps:

[0019] (1) in an atmosphere having an oxygen content of not more than 20 ppm, subjecting the monomer to a polymerization reaction in a first reactor containing a solvent to obtain a reaction solution;

[0020] (2) sending the reaction solution obtained in step (1) into a second reactor to continue the polymerization reaction;

[0021] The set temperature of the second reactor is 10-60°C higher than the set temperature of the first reactor, preferably 10-40°C.

[0022] The oxygen content in the reaction atmosphere of step (1) and step (2) is preferably not higher than 8 ppm, and is more preferably an inert atmosphere (eg, an inert atmosphere, a nitrogen atmosphere).

[0023] According to the present invention, preferably, the set temperature of the first reactor is not less than 25°C, more preferably 80-220°C, for example 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 180°C, 200°C, 220°C, and the range formed by any two of the above points.

[0024] According to the present invention, preferably, the polymerization reaction time in step (1) is 0.5-5h. When the torque display value in the polymerization reaction torque monitoring device in step (1) is 1.0-1.1 times the initial torque, the polymerization reaction is terminated at this time, and the reaction solution is sent to the second reactor to continue the polymerization reaction.

[0025] It should be noted that the polymerization reaction time in step (1) and step (2) refers to the time during which the polymerization reaction is kept at a set temperature, and does not include the time spent in the heating process.

[0026] According to the present invention, preferably, the set temperature of the second reactor is 100-260°C, for example 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, and the range formed by any two of the above points.

[0027] According to the present invention, preferably, the polymerization reaction time in step (2) is 2-10 hours. When the torque of the polymerization reaction liquid in step (2) is 1.1-1.6 times the initial torque, the polymerization reaction is terminated and the reaction liquid is sent to a post-processing unit.

[0028] The polymerization reaction of step (1) and / or step (2) can be carried out under stirring. Preferably, the stirring speed is 40-200 rpm, more preferably 80-150 rpm.

[0029] Preferably, the second reactor is heated to the set temperature 10-30 minutes in advance to avoid the temperature difference affecting the reaction process.

[0030] According to the present invention, preferably, step (1) comprises adding an aromatic component containing at least four amino groups and an aromatic or aliphatic component containing at least two carboxyl groups into a first reactor filled with a solvent, and maintaining the temperature for 0.5-3 hours.

[0031] According to the present invention, preferably, the monomer comprises an aromatic component comprising at least four amino groups and an aromatic or aliphatic component comprising at least two carboxyl groups.

[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, substituted or unsubstituted alkenyl group, for example, X is selected from

[0035] -O-, -S-, 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; more preferably 1:0.9-1.2.

[0042] 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 10-160 mmol, more preferably 20-50 mmol, per 100 g of the solvent.

[0043] According to the present invention, preferably, the method further comprises, before performing step (1), keeping the first reactor filled with the solvent at a set temperature for 0.5-2 hours.

[0044] According to the present invention, preferably, the solvent is a mixed solution of methanesulfonic acid and phosphorus pentoxide or polyphosphoric acid; preferably, the amount of phosphorus pentoxide used is 2-10 g (for example, 2 g, 3 g, 4 g, 5 g, 6 g, 7 g, 8 g, 9 g, 10 g, and a range consisting of any two of the above) per 100 g of methanesulfonic acid.

[0045] According to the present invention, when the solvent is a mixed solution of methanesulfonic acid and phosphorus pentoxide, the set temperature of the first reactor is 80-140°C; the set temperature of the second reactor is 120-150°C.

[0046] According to the present invention, when the solvent is polyphosphoric acid, the set temperature of the first reactor is 100-220°C; the set temperature of the second reactor is 160-240°C.

[0047] According to the present invention, preferably, the method further comprises placing methanesulfonic acid and phosphorus pentoxide in a dissolving kettle and stirring at 40-100° C. for 2-8 hours to obtain a clear solvent.

[0048] According to the present invention, preferably, the first reactor and the second reactor are each independently a reactor, and the reactor may be equipped with a heating device, a temperature control device, and a stirring device, and a feed port is set at the top of the reactor and a discharge port is set at the bottom. The reactor is also equipped with a torque recorder and / or a viscosity monitoring device to facilitate monitoring of the reaction process. The material transfer between two or more reactors is preferably carried out by gravity. More preferably, the first reactor and the second reactor each independently include at least one reactor; preferably include 1-3 reactors.

[0049] According to the present invention, preferably, when the number of reaction kettles in the first reactor is greater than 1, the reaction kettles in the first reactor are connected in series and / or in parallel.

[0050] According to the present invention, preferably, when the number of reaction kettles in the second reactor is greater than 1, the reaction kettles in the second reactor are connected in series and / or in parallel.

[0051] According to a preferred embodiment of the present invention, the first reactor and the second reactor each independently include a reactor, and the two reactors are connected in series.

[0052] According to another preferred embodiment of the present invention, the first reactor includes one reactor, the second reactor includes two reactors, and the three reactors are connected in series or in parallel.

[0053] The method of the present invention further comprises post-processing the reaction solution obtained in step (2), wherein the post-processing comprises sequentially washing the reaction solution obtained in step (2) with water / alkali, crushing, and drying.

[0054] The present invention will be described in detail below by way of examples. In the following examples,

[0055] The analysis method and test conditions of hydrogen spectrum were as follows: Agilent 400-MR DD2 nuclear magnetic resonance spectrometer was used, the frequency was 400 MHz, tetramethylsilane (TMS) was used as the internal standard, the solvent was DMSO-d6, and the test temperature was 40°C.

[0056] Thermogravimetric analysis method and test conditions: The test was conducted in a nitrogen atmosphere using a Q500 thermogravimetric analyzer from TA, USA. The heating rate was 10°C / min and the temperature range was 25-700°C.

[0057] Infrared analysis method and test conditions: Thermo Fisher Scientific Nicolet 6700 Fourier transform infrared spectrometer was used, with a spectral range of 4000-500cm -1 .

[0058] All raw materials are commercially available.

[0059] Example 1

[0060] The polymerization system includes a dissolving kettle, a first reactor, a second reactor, and a post-processing unit which are connected in sequence; the polymerization system also includes a tail gas treatment unit, and exhaust ports are provided on the tops of the first reactor and the second reactor, which are respectively connected to the tail gas treatment units.

[0061] The process of preparing polybenzimidazole in the above polymerization system includes:

[0062] (1) Methanesulfonic acid and phosphorus pentoxide (weight ratio of 12:1, total weight of 1.2 kg) were added into the dissolving kettle through the inlet, and heated and stirred at 80°C for 4 hours. The mixed solution of methanesulfonic acid and phosphorus pentoxide was introduced into the first reaction kettle through the solution delivery pipeline, and the temperature was raised to 120°C under nitrogen purge and kept warm for 30 minutes. Then 3,3′,4,4′-tetraaminobiphenyl and 4,4′-diphenyl ether dicarboxylic acid were added, and the temperature was kept warm for 90 minutes to obtain the first reaction solution, in which the molar ratio of tetraamine to diacid was 1:1, and the total molar ratio of tetraamine to diacid was 560 mmol.

[0063] (2) The first reaction liquid is introduced into the second reaction kettle which has been preheated to 120° C. through a solution delivery pipeline, and the temperature is raised to 140° C. The torque is recorded. After 5 hours, the torque increases by 1.2 times, and the reaction is terminated to obtain the second reaction liquid.

[0064] The stirring speed was maintained at 100 rpm throughout the reaction of step (1) and step (2).

[0065] (3) The gases generated by the first and second reactors enter the tail gas treatment unit through the exhaust hole and are discharged after being treated. The second reaction liquid is transported to the post-treatment unit through the solution delivery pipeline, and is washed with water / alkali, crushed, and dried in sequence to obtain a finished product with a mass of 118 g.

[0066] Example 2

[0067] The polymerization system includes a dissolution kettle, a first reactor, a second reactor, a third reactor, and a post-processing unit connected in sequence; the polymerization system also includes a tail gas treatment unit, and exhaust ports are provided on the tops of the first reactor, the second reactor, and the third reactor, which are respectively connected to the tail gas treatment units.

[0068] The process of preparing polybenzimidazole in the above polymerization system includes:

[0069] (1) Methanesulfonic acid and phosphorus pentoxide (weight ratio of 12:1, total weight of 2.2 kg) were added into the dissolving kettle through the inlet, and heated and stirred at 80°C for 4 hours. The mixed solution of methanesulfonic acid and phosphorus pentoxide was introduced into the first reaction kettle through the solution delivery pipeline, and the temperature was raised to 120°C under nitrogen purge and kept warm for 30 minutes. Then 3,3′,4,4′-tetraaminobiphenyl and isophthalic acid were added, and the temperature was kept warm for 60 minutes to obtain the first reaction solution, in which the molar ratio of tetraamine to diacid was 1:1, and the total molar ratio of tetraamine to diacid was 560 mmol.

[0070] (2) The first reaction liquid is introduced into the second reaction kettle which has been preheated to 120°C through the solution delivery pipeline, and the temperature is raised to 140°C. The torque is recorded and the temperature is kept for 1 hour to obtain the second reaction liquid. The second reaction liquid is introduced into the third reaction kettle which has been preheated to 140°C through the solution delivery pipeline, and the reaction is carried out at 140°C. The torque is monitored. After 4 hours, the torque increases by 1.1 times, and the reaction is terminated to obtain the third reaction liquid.

[0071] The stirring speed was maintained at 100 rpm throughout the reaction of step (1) and step (2).

[0072] (3) The gases generated by the first reactor, the second reactor and the third reactor enter the tail gas treatment unit through the exhaust hole and are discharged after being treated. The third reaction liquid is transported to the post-treatment unit through the solution delivery pipeline, and is washed with water / alkali, crushed and dried in sequence to obtain a finished product with a mass of 95g.

[0073] Example 3

[0074] The polymerization system includes a first reactor, a second reactor, and a post-processing unit which are connected in sequence; the polymerization system also includes a tail gas treatment unit, and exhaust ports are provided on the tops of the first reactor and the second reactor, which are respectively connected to the tail gas treatment units.

[0075] The process of preparing polybenzimidazole in the above polymerization system includes:

[0076] (1) 1.6 kg of polyphosphoric acid was added to the first reaction kettle through the inlet, and the temperature was raised to 120° C. and kept warm for 1 hour under nitrogen purge. 3,3′,4,4′-tetraaminobiphenyl and isophthalic acid were then added, and the temperature was kept warm for 2 hours to obtain a first reaction solution, in which the molar ratio of tetraamine to diacid was 1:1, and the total molar ratio of tetraamine to diacid was 560 mmol.

[0077] (2) The first reaction liquid is introduced into the second reaction kettle which has been preheated to 120° C. through a solution delivery pipeline, and the temperature is raised to 180° C. The torque is recorded. After 5 hours, the torque increases by 1.3 times, and the reaction is terminated to obtain the second reaction liquid.

[0078] The stirring speed was maintained at 100 rpm throughout the reaction of step (1) and step (2).

[0079] (3) The gases generated by the first and second reaction kettles enter the tail gas treatment unit through the exhaust hole and are discharged after being treated. The second reaction liquid is transported to the post-treatment unit through the solution delivery pipeline, and is washed with water / alkali, crushed, and dried in sequence to obtain a finished product with a mass of 96g.

[0080] Comparative Example 1

[0081] Methanesulfonic acid and phosphorus pentoxide (weight ratio 12:1, total weight 1.2 kg) were added to the reactor through the reactor inlet, and heated and stirred at 80°C for 4 hours. The reactor was heated to 120°C under nitrogen purge and kept warm for 30 minutes. 3,3′,4,4′-tetraaminobiphenyl and 4,4′-diphenyl ether dicarboxylic acid were added and kept warm for 90 minutes. The reactor was heated to 140°C, and the torque was recorded. After 5 hours, the torque increased by 1.2 times, and the reaction was terminated to obtain a reaction solution. Among them, the molar ratio of tetraamine to diacid was 1:1, and the total molar ratio of tetraamine to diacid was 560 mmol. The stirring speed was kept at 100 rpm throughout the reaction.

[0082] The post-treatment process of the reaction solution was the same as that of Example 1. The mass of the finished product was 119 g.

[0083] Comparative Example 2

[0084] Methanesulfonic acid and phosphorus pentoxide (weight ratio 12:1, total weight 2.2 kg) were added to the reactor through the reactor inlet, and heated and stirred at 80°C for 4 hours. The reactor was heated to 120°C under nitrogen purge and kept warm for 30 minutes. 3,3′,4,4′-tetraaminobiphenyl and isophthalic acid were added and kept warm for 60 minutes. The reactor was heated to 140°C and the torque was recorded. After 5 hours, the torque increased by 1.1 times, and the reaction was terminated to obtain a reaction solution. The molar ratio of tetraamine to diacid was 1:1, and the total molar ratio of tetraamine to diacid was 560 mmol. The stirring speed was kept at 100 rpm throughout the reaction.

[0085] The post-treatment process of the reaction solution is the same as that of Example 2. The mass of the finished product is 95 g.

[0086] Comparative Example 3

[0087] 1.6 kg of polyphosphoric acid was added to the reactor through the reactor inlet, and the temperature was raised to 120°C under nitrogen purge and kept warm for 1 hour. 3,3′,4,4′-tetraaminobiphenyl and isophthalic acid were added and kept warm for 2 hours. The reactor was heated to 180°C and the torque was recorded. After 5 hours, the torque increased by 1.3 times, and the reaction was terminated to obtain a reaction solution. The molar ratio of tetraamine to diacid was 1:1, and the total molar ratio of tetraamine to diacid was 560 mmol. The stirring speed was kept at 100 rpm throughout the reaction.

[0088] The post-treatment process of the reaction solution is the same as that of Example 3. The mass of the finished product is 95 g.

[0089] By comparing the polybenzimidazole yields of the embodiment and the comparative example, it is found that the two yields are close, indicating that the method of the present invention will not affect the product yield of a single production cycle of polybenzimidazole.

[0090] The discharging cycles of the embodiments and comparative examples are shown in Table 1. From Table 1, it can be seen that the discharging cycle (residence time in a single reactor) of polybenzimidazole produced by the method of the present invention can be significantly shortened, the equipment utilization rate can be improved, and the annual output of polybenzimidazole can be increased.

[0091] Table 1

[0092]

[0093] In addition, by Figure 1-3 It can be seen that the nuclear magnetic hydrogen spectrum, thermogravimetric analysis spectrum and infrared spectrum of the polybenzimidazole prepared in Example 1 are similar to those of Comparative Example 1, indicating that the properties of the polybenzimidazole powder prepared in Example 1 are no different from those of Comparative Example 1. Similarly, there are no differences in the properties of the polybenzimidazole obtained in Example 2 and Comparative Example 2, and in Example 3 and Comparative Example 3. The test results show that the production of polybenzimidazole by the method of the present invention does not affect the properties of the product.

[0094] 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 shortening the preparation cycle of polybenzimidazole, characterized in that: The method comprises the following steps: (1) in an atmosphere having an oxygen content of not more than 20 ppm, subjecting the monomer to a polymerization reaction in a first reactor containing a solvent to obtain a reaction solution; (2) sending the reaction solution obtained in step (1) into a second reactor to continue the polymerization reaction; The set temperature of the second reactor is 10-60° C. higher than the set temperature of the first reactor.

2. The method according to claim 1, wherein: The set temperature of the first reactor is not less than 25°C, preferably 80-220°C; And / or, the polymerization reaction time in step (1) is 0.5-5h.

3. The method according to claim 1, wherein: The set temperature of the second reactor is 100-260°C; And / or, the polymerization reaction time in step (2) is 2-10 hours.

4. The method according to claim 1, wherein: The monomers include an aromatic component containing at least four amino groups and an aromatic or aliphatic component containing at least two carboxyl groups.

5. The method according to claim 4, wherein: 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; more preferably 1:0.9-1.2; 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 10-160 mmol, more preferably 20-50 mmol, per 100 g of the solvent.

6. The method according to claim 1, wherein: The solvent is a mixed solution of methanesulfonic acid and phosphorus pentoxide or polyphosphoric acid.

7. The method according to claim 6, wherein: The amount of phosphorus pentoxide used is 2-10 g per 100 g of methanesulfonic acid.

8. The method according to claim 7, wherein: The method further comprises placing methanesulfonic acid and phosphorus pentoxide in a dissolving kettle and stirring at 40-100° C. for 2-8 hours; And / or, the method further comprises, before performing step (1), keeping the first reactor filled with the solvent at a set temperature for 0.5-2 hours.

9. The method according to any one of claims 1 to 8, wherein: The first reactor and the second reactor each independently include at least one reaction vessel; preferably include 1 to 3 reaction vessels.

10. The method according to claim 9, wherein: When the number of reaction kettles in the first reactor is greater than 1, the reaction kettles in the first reactor are connected in series and / or in parallel; And / or, when the number of reaction kettles in the second reactor is greater than 1, the reaction kettles in the second reactor are connected in series and / or in parallel.

Images