Polybenzimidazole and polymer film as well as preparation method and application thereof

Abstract

The invention relates to the technical field of polybenzimidazole, and discloses polybenzimidazole, a polymer film and a preparation method and application thereof.The polybenzimidazole comprises a structural unit A and a structural unit B. The structural unit A is of a structure shown in the formula (1), the structural unit B is of a structure shown in the formula (2), and the structural unit B is of a structure shown in the formula (2). R1 and R2 are respectively and independently selected from any one of arylene, cycloalkylene, alkylidene, alkenylene, heteroalkylene and fluoroalkyl; r1 is different from R2; x1 and X2 are respectively and independently selected from any one of sub-fluorine-containing alkyl,-SO2 <-> and-CO <->; x1 and X2 are the same or different. The polybenzimidazole disclosed by the invention has relatively high light transmittance and relatively low haze, and the elongation at break of the film is relatively high.

Description

Technical Field

[0001] This invention relates to the field of polybenzimidazole technology, specifically to a polybenzimidazole and polymer film, its preparation method, and its application. Background Technology

[0002] Polybenzimidazole (PBI) is an aromatic heterocyclic polymer containing repeating benzimidazole structural units in its main chain. It is a high-performance engineering plastic with excellent high-temperature resistance, chemical stability, and mechanical properties. It can operate at temperatures up to 375°C, exhibiting excellent heat resistance and good mechanical strength. It is suitable for applications involving extreme high temperatures, harsh chemicals and plasma, or those requiring high durability and abrasion resistance.

[0003] Ultraviolet (UV) light has a short wavelength and high energy, which can easily cause chemical bond breakage and alter the properties of materials. UV radiation is one of the main causes of photoaging in materials. Polybenzimidazole (PB) has good absorption of UV light and can be used as a UV absorbing film to absorb the UV spectrum and extend the lifespan of devices. However, PB film is usually yellowish-brown and dark in color, which results in poor light transmittance and greatly limits its application in the optical field. PB film cannot be used in some fields with high transparency requirements, such as flexible displays and flexible backsheets for solar cells.

[0004] Polybenzimidazole materials typically have low solubility. Homopolymerized polybenzimidazole also suffers from an overly rigid structure and an overly regular molecular chain arrangement, making the resin difficult to dissolve and resulting in materials with excessive rigidity but insufficient toughness. Copolymerization can usually balance the properties of different structures to obtain materials with good overall performance. However, because copolymerization introduces molecular chain segments with different structures, the regular arrangement of the molecular chains is usually affected, which in turn leads to a decrease in the optical properties of the material. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of existing polybenzimidazoles, such as dark color, low light transmittance, and low toughness, and to provide a polybenzimidazole, a polybenzimidazole film, its preparation method, and its application. This polybenzimidazole film can maintain high light transmittance while ensuring good mechanical properties, thus broadening the application field of polybenzimidazole.

[0006] To achieve the above objectives, a first aspect of the present invention provides a polybenzimidazole comprising structural unit A and structural unit B, wherein structural unit A has the structure shown in formula (1), and structural unit B has the structure shown in formula (2).

[0007]

[0008] R1 and R2 are each independently selected from any one of arylene, cycloalkyl, alkylene, alkenyl, heterocyclic, and fluorinated alkylene groups; and R1 and R2 are different; X1 and X2 are each independently selected from any one of fluorinated alkylene groups, -SO2-, and -CO-; X1 and X2 may be the same or different.

[0009] A second aspect of the present invention provides a method for preparing polybenzimidazole, the method comprising: polymerizing a monomer in a first solvent under polymerization reaction conditions;

[0010] The monomers include monomer a, monomer b, and monomer c, wherein monomer a is selected from at least one of the structures shown in formula (1-1), and monomer b and monomer c are each independently selected from any one of the structures shown in HOOC-R-COOH; and monomer b is different from monomer c.

[0011]

[0012] Wherein, R is selected from any one of arylene, cycloalkyl, alkylene, alkenyl, heterocyclic, and fluorinated alkylene groups; X is selected from any one of fluorinated hydrocarbon groups, -SO2-, and -CO-.

[0013] A third aspect of the present invention provides polybenzimidazole prepared by the method described above.

[0014] A fourth aspect of the present invention provides a polymer film containing polybenzimidazole, wherein the polybenzimidazole is the polybenzimidazole described above.

[0015] The fifth aspect of the present invention provides a method for preparing a polymer film, the method comprising: contacting the above-described polybenzimidazole with a second solvent to obtain a solution A; preparing a liquid film from solution A with or without solid-liquid separation, and then drying the solution to obtain a polymer film.

[0016] The sixth aspect of the present invention provides a polymer film prepared by the method described above.

[0017] The seventh aspect of the present invention provides the use of the above-described polybenzimidazole and / or the above-described polymer film in light-transmitting materials.

[0018] Through the above technical solution, the present invention achieves the following beneficial effects:

[0019] (1) When the polybenzimidazole of the present invention is made into a film, the film is light in color and nearly colorless and transparent. Under a standard C light source, it has high light transmittance and low haze. The film also has high toughness (high elongation at break). It can be used to prepare high light transmittance and high flexibility films, thus expanding the application field of polybenzimidazole.

[0020] (2) When the polybenzimidazole of the present invention is made into a thin film, it has good absorption capacity for ultraviolet light and can delay the photoaging of the device.

[0021] (3) In a preferred embodiment of the present invention, polybenzimidazole not only has an almost colorless and transparent appearance, high light transmittance, low haze and high toughness, but also has a high viscosity-average molecular weight and good solubility, which is beneficial for subsequent processing and application. Attached Figure Description

[0022] Figure 1 The image shows the 1H NMR spectrum of the polybenzimidazole prepared in Example 1.

[0023] Figure 2 These are the 1H NMR spectra of polybenzimidazole prepared in Preparation Example 2 and Preparation Example 4;

[0024] Figure 3 This is the 1H NMR spectrum of the polybenzimidazole prepared in Preparation Example 5;

[0025] Figure 4 The image shows the 1H NMR spectrum of the polybenzimidazole prepared in Example 6.

[0026] Figure 5 This is the 1H NMR spectrum of the polybenzimidazole prepared in Preparation Example 7;

[0027] Figure 6 These are the UV-Vis spectra of the polybenzimidazole films from Examples 1-4. Detailed Implementation

[0028] The endpoints and any values ​​of the ranges disclosed herein 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 the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0029] The first aspect of the present invention provides a polybenzimidazole comprising structural unit A and structural unit B, wherein structural unit A has the structure shown in formula (1) and structural unit B has the structure shown in formula (2).

[0030]

[0031] R1 and R2 are each independently selected from any one of arylene, cycloalkyl, alkylene, alkenyl, heterocyclic, and fluorinated alkylene groups; and R1 and R2 are different; X1 and X2 are each independently selected from any one of fluorinated alkylene groups, -SO2-, and -CO-; X1 and X2 may be the same or different.

[0032] In this invention, the arylene group can be C6-C. 24 The arylene group can be either monocyclic or polycyclic. The monocyclic arylene group can be a substituted or unsubstituted phenylene group. The substituents in the monocyclic arylene group can be substituted or unsubstituted C1-C5 alkyl groups or hydroxyl groups, and the number of substituents in the monocyclic arylene group can be 1-3; the substituents in the C1-C5 alkyl group can be halogens (F, Cl, etc.). The polycyclic arylene group can be composed of substituted or unsubstituted C1-C5 alkylene groups, C2-C5 alkenyl groups, bridged cycloalkyl groups, -O-, ... It consists of at least one group and at least two monocyclic arylene groups; wherein, the number of monocyclic arylene groups in the polycyclic arylene group can be 2-5, and the number of -O- can be 1-3; the substituents of the C1-C5 alkylene group can be C1-C5 alkyl groups.

[0033] In this invention, the cycloalkylene group can be substituted or unsubstituted C6-C. 24 The cycloalkyl group includes, but is not limited to, cyclohexylene, cycloheptylene, cyclooctylene, and cyclononylene. The substituents in the cycloalkyl group can be C1-C5 alkyl groups.

[0034] In this invention, the subchain alkyl group can be substituted or unsubstituted C2-C. 20 The subchain alkyl group includes, but is not limited to, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, and decylene. The substituents of the subchain alkyl group can be C1-C5 alkyl groups.

[0035] In this invention, the imide group can be C2-C. 20 The subalkenyl group.

[0036] In this invention, the heterocyclic group can be a substituted or unsubstituted C3-C group. 20The heterocyclic group may contain at least one heteroatom selected from N, O, and S, preferably N; the number of heteroatoms may be 1-3. The heterocyclic group may be a monocyclic or polycyclic heterocyclic group; the monocyclic heterocyclic group may be a C3-C8 heterocyclic group; the polycyclic heterocyclic group may consist of at least two monocyclic heterocyclic groups, or at least one monocyclic heterocyclic group and at least one monocyclic aryl group. Monocyclic heterocyclic groups include, but are not limited to, pyridyl, pyrimidinyl, triazine, pyrroleyl, and imidazolyl groups. The monocyclic heterocyclic group may be a substituted monocyclic heterocyclic group, wherein the substituents of the monocyclic heterocyclic group may be C1-C5 alkyl, hydroxyl, etc.

[0037] According to the present invention, preferably, R1 and R2 are each independently selected from C6-C. 24 aryl, C6-C 24 Cycloalkylene, C2-C 20 Alkylene, C2-C 20 imidene group, C3-C 20 The heterocyclic group is selected from any one of the following: pyridyl, pyrroleyl, furanyl, quinolinyl, thiophenyl, pyranyl, and pyrazinyl. More preferably, the heterocyclic group is selected from any one of pyridyl, pyrrolidinyl, furanyl, quinolinyl, thiophenyl, pyranyl, and pyrazinyl.

[0038] According to the present invention, preferably, X1 and X2 are each independently selected from C1-C 10 The fluorinated hydrocarbon group; more preferably, the fluorinated hydrocarbon group is C1-C5; even more preferably, X1 and X2 are each independently -C(CF3)2-.

[0039] According to the present invention, preferably, R1 and R2 are each independently selected from any one of the groups shown in formulas (3) to (24): Where n is an integer between 2 and 8.

[0040] According to the present invention, preferably, R1 is a group shown in formula (3), and R2 is any one of the groups shown in formulas (4) to (24).

[0041] According to a preferred embodiment of the present invention, the structural unit A can be One of them; the structural unit B can be

[0042] One of them.

[0043] According to the present invention, preferably, the molar ratio of structural unit A to structural unit B is 0.05:1-20:1.

[0044] According to the present invention, preferably, the viscosity-average molecular weight of the polybenzimidazole is 2000-500000 g / mol; more preferably, it is 10000-300000 g / mol.

[0045] According to the present invention, preferably, the polybenzimidazole has good solubility in a good solvent; wherein the good solvent is selected from any one or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0046] According to the present invention, preferably, at 80°C, the time required for 1g of the polybenzimidazole to completely dissolve in 30mL of dimethyl sulfoxide is 0.5-8h, more preferably 0.5-3h.

[0047] According to the present invention, preferably, the intrinsic viscosity of the polybenzimidazole is 0.1-6.5 dL / g.

[0048] A second aspect of the present invention provides a method for preparing polybenzimidazole, the method comprising: polymerizing a monomer in a first solvent under polymerization reaction conditions;

[0049] The monomers include monomer a, monomer b, and monomer c, wherein monomer a is selected from at least one of the structures shown in formula (1-1), and monomer b and monomer c are each independently selected from any one of the structures shown in HOOC-R-COOH; and monomer b is different from monomer c.

[0050]

[0051] Wherein, R is selected from any one of arylene, cycloalkyl, alkylene, alkenyl, heterocyclic, and fluorinated alkylene groups; X is selected from any one of fluorinated hydrocarbon groups, -SO2-, and -CO-.

[0052] In this invention, the arylene, cycloalkyl, sub-alkyl, alkenyl, and heterocyclic groups are as described in the first aspect and will not be repeated here.

[0053] According to the present invention, preferably, X is selected from C1-C 10 The fluorinated hydrocarbon group; more preferably, the fluorinated hydrocarbon group is C1-C5; even more preferably, X is -C(CF3)2-.

[0054] According to the present invention, preferably, R is selected from C6-C. 24 aryl, C6-C 24 Cycloalkylene, C2-C 20 Sub-alkyl groups, C2-C 20 imidene group, C3-C 20 Any of the subheterocyclic groups.

[0055] According to the present invention, preferably, R is selected from any one of the groups shown in formulas (3)-(24): Where n is an integer between 2 and 8.

[0056] According to the present invention, preferably, HOOC-R-COOH is selected from at least one of the compounds shown in formula (3-1) to formula (24-1); Where n is an integer between 2 and 8.

[0057] According to the present invention, preferably, the molar ratio of the total amount of monomers b and c to the amount of monomer a is 0.9:1-1.1:1, for example, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, and any two of the above ranges.

[0058] According to the present invention, preferably, the molar ratio of monomer b to monomer c is 0.05-20:1; for example, 0.05:1, 0.1:1, 0.5:1, 1:1, 1.5:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 15:1, 20:1, and any range of any two of the above.

[0059] According to the present invention, the conditions for the polymerization reaction can be conventional polymerization reaction conditions in the art; preferably, the conditions for the polymerization reaction include: a polymerization temperature of 120-220°C (e.g., 120°C, 140°C, 160°C, 180°C, 200°C, 220°C, and any two of the above), and a polymerization time of 1-24 hours (e.g., 1 hour, 2 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 10 hours, 15 hours, 20 hours, 24 hours, and any two of the above). More preferably, the polymerization reaction is carried out under stirring.

[0060] According to the present invention, preferably, the polymerization reaction is carried out under an inert atmosphere. The inert atmosphere may be provided by at least one of nitrogen, argon, helium, and neon, preferably nitrogen.

[0061] According to the present invention, preferably, the first solvent includes at least one selected from polyphosphoric acid, methanesulfonic acid, phosphorus pentoxide, and phosphoric acid.

[0062] According to the present invention, preferably, the amount of the first solvent used is 2-20 kg relative to 1 mol of monomer a, for example, it can be 2 kg, 4 kg, 6 kg, 8 kg, 10 kg, 15 kg, 20 kg, and any two of the above ranges.

[0063] According to the present invention, the method further includes a step of extracting the polymer from the polymerization product. The polymer extraction process can be a method commonly used in the art. For example, the method further includes contacting a mixture containing polybenzimidazole obtained from the polymerization reaction with a precipitant to obtain polybenzimidazole. The precipitant can be water and / or an alkaline solution. The alkaline solution can be at least one of an aqueous solution of an alkali metal hydroxide, an aqueous solution of an alkaline earth metal hydroxide, an aqueous solution of an alkali metal salt, an aqueous solution of an alkaline earth metal salt, and ammonia; more preferably, at least one of ammonia, a saturated aqueous solution of sodium carbonate, an aqueous solution of potassium carbonate, an aqueous solution of sodium bicarbonate, an aqueous solution of potassium bicarbonate, an aqueous solution of magnesium carbonate, an aqueous solution of sodium hydroxide, and an aqueous solution of potassium hydroxide.

[0064] A third aspect of the present invention provides polybenzimidazole prepared by the method described above.

[0065] A fourth aspect of the present invention provides a polymer film containing polybenzimidazole, wherein the polybenzimidazole is the polybenzimidazole described above.

[0066] According to the present invention, preferably, the elongation at break of the polymer film is 2-300%.

[0067] According to the present invention, preferably, the transmittance of the polymer film is 70-100%, and the haze is 0-20%. The transmittance and haze are tested by measuring the polymer film with a thickness of 10-50 micrometers under a standard C light source.

[0068] According to the present invention, preferably, the polymer film further includes inorganic additives and / or polymer additives. More preferably, the inorganic additives include at least one selected from nano-silica, nano-titanium dioxide, graphene, nano-tin oxide, carbon nanotubes, fullerenes, and nano-zirconia. More preferably, the polymer additives include at least one selected from polyimide, polysulfone, polyetheretherketone, polybenzoxazole, polyethylene terephthalate, ethylene vinyl alcohol copolymer, polyolefin elastomer, polyethylene glycol, and polyethylene oxide.

[0069] According to the present invention, preferably, the content of the inorganic additive is 0-10 parts by weight relative to 100 parts by weight of polybenzimidazole, and the content of the polymer additive is 0-100 parts by weight.

[0070] The fifth aspect of the present invention provides a method for preparing a polymer film, the method comprising: contacting the above-described polybenzimidazole with a second solvent to obtain a solution A; preparing a liquid film from solution A with or without solid-liquid separation, and then drying the solution to obtain a polymer film.

[0071] In this invention, solution A can be prepared into a liquid membrane by solid-liquid separation and then using the filtrate, or it can be prepared directly into a liquid membrane without solid-liquid separation. Those skilled in the art can reasonably choose whether to perform solid-liquid separation based on the solid content and solubility in solution A.

[0072] According to the present invention, preferably, the second solvent comprises at least one selected from dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, methanesulfonic acid, formic acid, phosphoric acid, polyphosphoric acid, sulfuric acid, and trichlorotoluene.

[0073] According to the present invention, preferably, the content of polybenzimidazole is 0.1-20% by weight, based on the total weight of solution A.

[0074] According to the present invention, preferably, the contact conditions include: a contact temperature of 30-160°C (e.g., 30°C, 50°C, 60°C, 80°C, 100°C, 140°C, 160°C, and any two of the above ranges), and a contact time of 10 min-24 h (10 min, 30 min, 1 h, 2 h, 3 h, 4 h, 10 h, 20 h, 24 h, and any two of the above ranges). The contact can be carried out under stirring, wherein the linear velocity of the stirring is 0.05-1 m / s, more preferably 0.1-0.5 m / s.

[0075] In this invention, the solid-liquid separation method can be a commonly used solid-liquid separation method in the art. Preferably, the solid-liquid separation method is sand core funnel filtration; more preferably, the pore size of the sand core funnel is 30-50μm.

[0076] In this invention, the liquid film can be formed by pouring the liquid obtained from solid-liquid separation onto a substrate, and then using any one of the following methods: scraping, spraying, slot coating, or natural flow coating. The substrate can be a rigid substrate such as a glass plate, stainless steel plate, or polytetrafluoroethylene plate; or a flexible substrate such as a polyimide film, polyethylene terephthalate film, polysulfone film, cellulose film, or nonwoven fabric.

[0077] According to the present invention, preferably, the drying conditions include: a drying temperature of 60-160°C and a drying time of 0.5-24h.

[0078] According to the present invention, preferably, the method further includes: contacting an inorganic additive and / or a polymer additive with a second solvent to obtain a solution B, mixing solution B with solution A to obtain a solution C, then separating solution C into a liquid film through solid-liquid separation, and then drying the liquid film to obtain a polymer film.

[0079] According to the present invention, preferably, the conditions for contacting the inorganic additive and / or polymer additive with the second solvent include: a temperature of 30-160°C and a time of 0.5-24 hours. The contact method may be ultrasound.

[0080] According to the present invention, preferably, in order to promote the dissolution of polybenzimidazole, a co-solvent may be added when preparing solution A, wherein the co-solvent is selected from any one or more of lithium chloride, sodium chloride, and lithium trifluoromethanesulfonylimide.

[0081] The sixth aspect of the present invention provides a polymer film prepared by the method described above.

[0082] The seventh aspect of the present invention provides the use of the above-described polybenzimidazole and / or the above-described polymer film in light-transmitting materials.

[0083] According to the present invention, preferably, the light-transmitting material includes at least one of the following: a flexible backsheet of a solar cell, a flexible display substrate, and anti-counterfeiting packaging.

[0084] The present invention will be described in detail below through embodiments. In the following embodiments,

[0085] All raw materials are commercially available.

[0086] 3,3'-Diaminobenzidine (Sigma-Aldrich, 99%); 2,2-bis(3,4-aminophenyl)hexafluoropropane (Puyang Runtu New Materials Co., Ltd., 98%); 4,4-dicarboxylic acid diphenyl ether (J&K, 98%); isophthalic acid (J&K, 98%); cyclohexanedicarboxylic acid (Innochem, 98%); azelaic acid (Innochem, 98%); 3,5-pyridinedicarboxylic acid (J&K, 97%); 4 4,4'-Methylenebisbenzoic acid (J&K, 98%); 4,4'-(2,2-diphenylethylene-1,1-diyl)benzoic acid (Annegi Chemical, 98%); methanesulfonic acid (J&K, 98%); phosphorus pentoxide (J&K, 98%); sodium carbonate (J&K, 98%); N,N-dimethylacetamide (Innochem, 99.5%); dimethyl sulfoxide (J&K, 98%). All reagents were used directly without secondary purification.

[0087] The molar ratio of structural unit A to structural unit B in polybenzimidazole was quantitatively analyzed by nuclear magnetic resonance (NMR). The specific testing method was as follows: [The following text appears to be a separate, unrelated section:] Nuclear magnetic resonance spectrometer (Bruke DMX400, deuterated reagent d... 4 The test was performed on -CH3OH (tetramethylsilane (TMS) as an internal standard).

[0088] Preparation Example 1

[0089] This preparation example illustrates the preparation process of polybenzimidazole.

[0090] Under a nitrogen atmosphere, polyphosphoric acid (60 g), 2,2-bis(3,4-aminophenyl)hexafluoropropane (10 mmol), 4,4-dicarboxylic acid (8 mmol), and isophthalic acid (2 mmol) were added to a reactor. The mixture was stirred and heated to 200 °C for 4 h. After the reaction, the resulting solution was poured into a saturated sodium bicarbonate aqueous solution to precipitate the polymer. The polymer was then washed until neutral and placed in a vacuum oven at 80 °C for 24 h to obtain polybenzimidazole.

[0091] The structural formula of structural unit A in the prepared polybenzimidazole is as follows: The structural formula of structural unit B is as follows: The 1H NMR spectrum of polybenzimidazole is shown below. Figure 1 As shown, the molar ratio of structural unit A to structural unit B is 4.465:1, calculated from the 1H NMR spectrum of polybenzimidazole.

[0092] Preparation Example 2

[0093] This preparation example illustrates the preparation process of polybenzimidazole.

[0094] Under a nitrogen atmosphere, methanesulfonic acid (54 g), phosphorus pentoxide (5 g), 2,2-bis(3,4-aminophenyl)hexafluoropropane (10 mmol), cyclohexanedicarboxylic acid (2 mmol), and 4,4-dicarboxylic acid diphenyl ether (8 mmol) were added to a reactor. The mixture was stirred and heated to 140 °C for 6 h. After the reaction, the resulting solution was poured into a saturated sodium bicarbonate aqueous solution to precipitate the polymer. The polymer was then washed until neutral and placed in a vacuum oven at 80 °C for 24 h.

[0095] The structural formula of structural unit A in the prepared polybenzimidazole is as follows: The structural formula of structural unit B is as follows:

[0096] The 1H NMR spectrum of polybenzimidazole is shown below. Figure 2 As shown below, the molar ratio of structural unit A to structural unit B is 2.817:1, calculated from the 1H NMR spectrum of polybenzimidazole.

[0097] Preparation Example 3

[0098] Polybenzimidazole was prepared according to the method of Preparation Example 2, except that the amount of cyclohexanedicarboxylic acid used was 1 mmol and the amount of 4,4-dicarboxylic diphenyl ether used was 9 mmol.

[0099] The 1H NMR spectrum of polybenzimidazole is similar to that of Preparation Example 2 and will not be shown again. Calculations from the 1H NMR spectrum of polybenzimidazole show that the molar ratio of structural unit A to structural unit B is 3.657:1.

[0100] Preparation Example 4

[0101] Polybenzimidazole was prepared according to the method of Preparation Example 2, except that "2 mmol cyclohexanedicarboxylic acid" was replaced with "7 mmol azelaic acid", and the amount of 4,4-dicarboxylic diphenyl ether was 3 mmol.

[0102] The structural formula of structural unit A in the prepared polybenzimidazole is as follows: The structural formula of structural unit B is as follows:

[0103] The 1H NMR spectrum of polybenzimidazole is shown below. Figure 2 As shown above, the molar ratio of structural unit A to structural unit B is 0.524:1, calculated from the 1H NMR spectrum of polybenzimidazole.

[0104] Preparation Example 5

[0105] Polybenzimidazole was prepared according to the method of Preparation Example 2, except that "2 mmol cyclohexanedicarboxylic acid" was replaced with "5 mmol 4,4'-(2,2-diphenylethylene-1,1-diyl)dibenzoic acid", and the amount of 4,4-dicarboxylic diphenyl ether was 5 mmol. The reaction temperature was 120 °C, and the reaction time was 4 hours.

[0106] The structural formula of structural unit A in the prepared polybenzimidazole is as follows: The structural formula of structural unit B is as follows:

[0107] The 1H NMR spectrum of polybenzimidazole is shown below. Figure 3 As shown, the molar ratio of structural unit A to structural unit B is 1.028:1, calculated from the 1H NMR spectrum of polybenzimidazole.

[0108] Preparation Example 6

[0109] Polybenzimidazole was prepared according to the method of Preparation Example 1, except that "8 mmol 4,4-dicarboxylic acid diphenyl ether" was replaced with "1 mmol 3,5-pyridinedicarboxylic acid", and the amount of isophthalic acid was 9 mmol; the reaction time was 6 h.

[0110] The structural formula of structural unit A in the prepared polybenzimidazole is as follows: The structural formula of structural unit B is as follows:

[0111] The 1H NMR spectrum of polybenzimidazole is shown below. Figure 4As shown, the molar ratio of structural unit A to structural unit B is 0.09:1, calculated from the 1H NMR spectrum of polybenzimidazole.

[0112] Preparation Example 7

[0113] Polybenzimidazole was prepared according to the method of Preparation Example 1, except that "2 mmol isophthalic acid" was replaced with "5 mmol 4,4'-methylenebisbenzoic acid", and the amount of 4,4-dicarboxylic acid diphenyl ether was 5 mmol; the reaction time was 6 h.

[0114] The structural formula of structural unit A in the prepared polybenzimidazole is as follows: The structural formula of structural unit B is as follows:

[0115] The 1H NMR spectrum of polybenzimidazole is shown below. Figure 5 As shown, the molar ratio of structural unit A to structural unit B is 1.08:1, calculated from the 1H NMR spectrum of polybenzimidazole.

[0116] Comparative Preparation Example 1

[0117] Polybenzimidazole was prepared according to the method of Preparation Example 1, except that "2,2-bis(3,4-aminophenyl)hexafluoropropane" was replaced with an equimolar amount of "3,3-diaminobenzidine".

[0118] Comparative Preparation Example 2

[0119] Polybenzimidazole was prepared according to the method of Preparation Example 2, except that "2,2-bis(3,4-aminophenyl)hexafluoropropane" was replaced with an equimolar amount of "3,3-diaminobenzidine".

[0120] Comparative preparation example 3

[0121] Polybenzimidazole was prepared according to the method of Preparation Example 2, except that the amount of cyclohexanedicarboxylic acid used was 10 mmol, and 4,4-dicarboxylic diphenyl ether was not added.

[0122] Comparative preparation example 4

[0123] Polybenzimidazole was prepared according to the method of Preparation Example 1, except that the amount of 4,4-dicarboxylic acid diphenyl ether was 10 mmol and isophthalic acid was not added.

[0124] Comparative preparation example 5

[0125] Polybenzimidazole was prepared according to the method of Preparation Example 1, except that the amount of isophthalic acid used was 10 mmol and 4,4-dicarboxylic acid was not added.

[0126] Comparative preparation example 6

[0127] Polybenzimidazole was prepared according to the method of Comparative Preparation Example 4, except that "2,2-bis(3,4-aminophenyl)hexafluoropropane" was replaced with an equimolar amount of "3,3-diaminobenzidine".

[0128] Comparative preparation example 7

[0129] Polybenzimidazole was prepared according to the method of Comparative Preparation Example 5, except that "2,2-bis(3,4-aminophenyl)hexafluoropropane" was replaced with an equimolar amount of "3,3-diaminobenzidine".

[0130] Test Example 1

[0131] The intrinsic viscosity and viscosity-average molecular weight of polybenzimidazole (PBI) prepared in the test preparation example and the comparative preparation example are shown in Table 1.

[0132] (1) Test method for intrinsic viscosity: PBI powder was dissolved in concentrated sulfuric acid (98wt%) to prepare a sulfuric acid solution with a concentration of 0.6 g / dL. The sulfuric acid solution was added to an Ubbelohde viscometer with a capillary inner diameter of 1.0-1.1 mm and stabilized in a constant temperature water bath at 25℃ for 30 min. The outflow time of the solution was recorded as t1, the outflow time of the concentrated sulfuric acid was recorded as t0, and the concentration of the polymer solution was recorded as C. The intrinsic viscosity of PBI was calculated according to Formula 1 and Formula 2.

[0133] Increased specific viscosity

[0134] Intrinsic viscosity

[0135] The viscosity-average molecular weight M of the polymer is obtained by conversion from the Mark–Houwink–Sakurada equation (Equation 3), where the constant is taken as K = 1.94 × 10⁻⁶. -4 , α=0.791.

[0136] [η]=KM α Formula 3

[0137] (2) Test method for initial decomposition temperature: The sample was tested using a Netzsch STA409PC; the test atmosphere was N2 atmosphere, the flow rate was 50 mL / min; the heating rate was 10 K / min, and the scan range was 298–1273 K.

[0138] (3) Test method for dissolution time: Take 1g of polybenzimidazole sample and disperse it in 30mL of dimethyl sulfoxide, and dissolve it under stirring at 80℃. Test the time required for complete dissolution.

[0139] Table 1

[0140]

[0141]

[0142] Example 1

[0143] This embodiment illustrates the preparation process of polybenzimidazole films.

[0144] (1) 1g of polybenzimidazole prepared in Preparation Example 1 was added to 30mL of dimethyl sulfoxide and stirred at 80°C for 2h to dissolve the polybenzimidazole and obtain a solution. The linear speed of stirring was 0.31m / s.

[0145] (2) The solution was filtered using a G2 pore size sand core funnel (pore size 30-50μm) to obtain filtrate. The filtrate was then poured onto a glass plate and coated with a 500μm scraper to form a uniform liquid film on the glass plate.

[0146] (3) The glass plate with liquid film was dried at 80°C for 12 hours to obtain a polybenzimidazole film with a thickness of 25±3μm.

[0147] Example 2

[0148] Polybenzimidazole films were prepared according to the method of Example 1, except that the polybenzimidazole in Preparation Example 1 was replaced with an equal weight of polybenzimidazole in Preparation Example 2.

[0149] Example 3

[0150] Polybenzimidazole films were prepared according to the method of Example 2, except that the polybenzimidazole in Preparation Example 2 was replaced with an equal weight of polybenzimidazole in Preparation Example 3.

[0151] Example 4

[0152] Polybenzimidazole films were prepared according to the method of Example 2, except that the polybenzimidazole in Preparation Example 2 was replaced with an equal weight of polybenzimidazole in Preparation Example 4.

[0153] Example 5

[0154] Polybenzimidazole films were prepared according to the method of Example 2, except that the polybenzimidazole in Preparation Example 2 was replaced with an equal weight of polybenzimidazole in Preparation Example 5.

[0155] Example 6

[0156] Polybenzimidazole films were prepared according to the method of Example 2, except that the polybenzimidazole in Preparation Example 2 was replaced with an equal weight of the polybenzimidazole in Preparation Example 6.

[0157] Example 7

[0158] Polybenzimidazole films were prepared according to the method of Example 2, except that the polybenzimidazole in Preparation Example 2 was replaced with an equal weight of the polybenzimidazole in Preparation Example 7.

[0159] Comparative Example 1

[0160] Polybenzimidazole films were prepared according to the method of Example 1, except that the polybenzimidazole in Preparation Example 1 was replaced with an equal weight of the polybenzimidazole in Comparative Preparation Example 1, and in step (1), when preparing the polybenzimidazole solution, the mass fraction of the co-solvent lithium chloride added was 5% of the polybenzimidazole material, and the dissolution time was 3 hours. The thickness of the film was 26 ± 3 μm.

[0161] When no co-solvent was added during the preparation of the polybenzimidazole solution in Comparative Example 1, a large number of powdery particles remained unswelled after 8 hours of dissolution; after adding the co-solvent, the solution became a semi-gel state after 1 hour of dissolution.

[0162] Comparative Example 2

[0163] Polybenzimidazole films were prepared according to the method of Example 2, except that the polybenzimidazole in Preparation Example 2 was replaced with an equal weight of the polybenzimidazole in Comparative Preparation Example 2, and in step (1) when preparing the polybenzimidazole solution, the mass fraction of the cosolvent lithium chloride was 8% of the polybenzimidazole material, and the dissolution time was 5h.

[0164] When no co-solvent was added during the preparation of the polybenzimidazole solution in Comparative Example 2, the polybenzimidazole structure was difficult to dissolve; after adding the co-solvent, the dissolution time was longer.

[0165] Comparative Example 3

[0166] Polybenzimidazole films were prepared according to the method of Example 2, except that the polybenzimidazole in Preparation Example 2 was replaced with an equal weight of the polybenzimidazole in Comparative Preparation Example 3.

[0167] However, compared to the polybenzimidazole prepared in Example 3, the film-forming properties were poor, and it was unable to form a large-area self-supporting film. The film was extremely fragile and could not be tested for mechanical properties.

[0168] Comparative Examples 4-7

[0169] Polybenzimidazole films were prepared according to the method of Example 1, except that the polybenzimidazole in Preparation Example 1 was replaced with equal weights of the polybenzimidazole in Comparative Preparation Examples 4-7.

[0170] Test Example 2

[0171] The transmittance, haze, elongation at break, tensile strength, and tensile modulus of the polybenzimidazole film were tested, and the test results are shown in Table 2.

[0172] (1) Test method for transmittance and haze: The transmittance and haze were obtained by using a WGT-S transmittance / haze tester (Shanghai Shenguang Instrument Co., Ltd.) and a standard C light source.

[0173] (2) Mechanical property test: At room temperature (25±2)℃ and humidity (50±10)%, the mechanical properties (elongation at break, tensile strength, and amount of film stretched) of the film sample were tested using an Instron 5965 universal tensile testing instrument with a tensile rate of 1mm / min and an initial distance of 15mm between the upper and lower clamps.

[0174] (3) Test method for the ultraviolet-visible spectroscopy of polybenzimidazole film: The results were obtained using a UV-Vis-NIR spectrometer (Shimadzu UV3600, Japan). The ultraviolet absorption of the polybenzimidazole films in Examples 1-4 is shown below. Figure 6 As shown, by Figure 6 It can be seen that in the ultraviolet light band, almost all ultraviolet light is absorbed.

[0175] Table 2

[0176]

[0177] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A polybenzimidazole, characterized in that, The polybenzimidazole comprises structural unit A and structural unit B, wherein structural unit A has the structure shown in formula (1) and structural unit B has the structure shown in formula (2). R1 and R2 are each independently selected from any one of arylene, cycloalkyl, alkylene, alkenyl, heterocyclic, and fluorinated alkyl groups; and R1 and R2 are different; X1 and X2 are each independently selected from any one of fluorinated alkyl groups, -SO2-, and -CO-; X1 and X2 may be the same or different.

2. The polybenzimidazole according to claim 1, wherein, R1 and R2 are each independently selected from C6-C 24 aryl, C6-C 24 Cycloalkylene, C2-C 20 Sub-alkyl groups, C2-C 20 imidene group, C3-C 20 Any one of the subheterocyclic groups; X1 and X2 are each independently selected from C1-C 10 Fluorinated hydrocarbon groups; Preferably, the heterocyclic group is selected from any one of pyridylene, pyrroleylene, furanylene, quinolinylene, thiophenylene, pyranylene, and pyrazinylene.

3. The polybenzimidazole according to claim 1, wherein, R1 and R2 are each independently selected from any one of the groups shown in formulas (3) to (24): Where n is an integer from 2 to 8; Preferably, R1 is the group shown in formula (3), and R2 is any one of the groups shown in formulas (4) to (24).

4. The polybenzimidazole according to claim 1, wherein, The molar ratio of structural unit A to structural unit B is 0.05:1-20:1; And / or, the viscosity-average molecular weight of the polybenzimidazole is 2000-500000 g / mol; preferably 10000-300000 g / mol; And / or, the intrinsic viscosity of the polybenzimidazole is 0.1-6.5 dL / g.

5. A method for preparing polybenzimidazole, characterized in that, The method includes: polymerizing the monomer in a first solvent under polymerization reaction conditions; The monomers include monomer a, monomer b, and monomer c, wherein monomer a is selected from at least one of the structures shown in formula (1-1), and monomer b and monomer c are each independently selected from any one of the structures shown in HOOC-R-COOH; and monomer b is different from monomer c. Wherein, R is selected from any one of arylene, cycloalkylene, chain alkylene, alkenylene, heterocyclic, and fluorinated alkylene groups; X is selected from any one of fluorinated alkylene, -SO2-, and -CO-. Preferably, R is selected from C6-C. 24 aryl, C6-C 24 Cycloalkylene, C2-C 20 Sub-alkyl groups, C2-C 20 imidene group, C3-C 20 Any of the subheterocyclic groups; X is selected from C1-C 10 Fluorinated hydrocarbon groups.

6. The method according to claim 5, wherein, R is selected from any one of the groups shown in formulas (3) to (24): Where n is an integer between 2 and 8.

7. The method according to claim 5, wherein, The total amount of monomers b and c is used in a molar ratio of 0.9:1 to 1.1:1 to monomer a. And / or, the molar ratio of monomer b to monomer c is 0.05:1-20:1; And / or, the conditions for the polymerization reaction include: a polymerization temperature of 120-220°C and a polymerization time of 1-24 h; And / or, the polymerization reaction is carried out in an inert atmosphere; And / or, the first solvent includes at least one of polyphosphoric acid, methanesulfonic acid, phosphorus pentoxide, and phosphoric acid; And / or, the amount of the first solvent used is 2-20 kg relative to each 1 mol of monomer a.

8. Polybenzimidazole prepared by the method according to any one of claims 5-7.

9. A polymer film, characterized in that, The polymer film contains polybenzimidazole, which is the polybenzimidazole described in any one of claims 1-4 and 8.

10. The polymer film according to claim 9, wherein, The elongation at break of the polymer film is 2-300%; And / or, the polymer film has a light transmittance of 70-100% and a haze of 0-20%.

11. A method for preparing a polymer film, characterized in that, The method includes: contacting the polybenzimidazole of any one of claims 1-4 and 8 with a second solvent to obtain solution A; preparing a liquid film from solution A with or without solid-liquid separation, and then drying it to obtain a polymer film.

12. The method according to claim 11, wherein, The second solvent includes at least one of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, methanesulfonic acid, formic acid, phosphoric acid, polyphosphoric acid, sulfuric acid, and trichlorotoluene; And / or, based on the total weight of solution A, the content of the polybenzimidazole is 0.1-20% by weight; And / or, the contact conditions include: a contact temperature of 30-160°C and a contact time of 10 min-24 h; the contact is carried out under stirring, and the linear velocity of the stirring is 0.05-1 m / s, preferably 0.1-0.5 m / s; And / or, the drying conditions include: a drying temperature of 60-160°C and a drying time of 0.5-24 hours.

13. A polymer film prepared by the method of claim 11 or 12.

14. The use of the polybenzimidazole film according to any one of claims 1-4 and 8 and / or the polymer film according to any one of claims 9, 10 and 13 in light-transmitting materials.

15. The application according to claim 14, wherein, The light-transmitting material includes at least one of the following: a flexible backsheet for solar cells, a flexible display substrate, and anti-counterfeiting packaging.

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