Polyimide containing benzimidazole group and preparation method and application thereof

Abstract

The present invention designs the molecular formula of polyimide so that the polyimide has the advantages of high glass transition temperature and low thermal expansion coefficient. Furthermore, the preparation method of the benzimidazole-containing polyimide provided in the present invention is simple to operate and easy to industrialize.

Description

Technical Field

[0001] The present application relates to the technical field of polymer materials, and in particular to a benzimidazole-containing polyimide and a preparation method and application thereof. Background Art

[0002] Polyimide (PI) is an insulating material with excellent heat resistance, which is widely used in electronics, electrical engineering, aerospace and other industries.

[0003] Polyimide is generally prepared by polymerization of diamine monomers and dianhydride monomers. Traditional polyimide films have significant thermal expansion, with a thermal expansion coefficient of 45ppm / K, which limits the application of polyimide as structural parts and insulating materials in the nuclear field. At present, the thermal expansion coefficient of benzimidazole-based polyimide films has good dimensional stability, with a thermal expansion coefficient of 8 to 21ppm / K, but its expansion coefficient needs to be further reduced to be used in high temperature and radiation environments; at the same time, the glass transition temperature of existing benzimidazole-based polyimide films is around 300℃, which cannot meet the high temperature resistance requirements. Summary of the invention

[0004] Based on this, the present application provides a benzimidazole-containing polyimide and a preparation method and application thereof. The benzimidazole-containing polyimide provided in the present application has the advantages of high glass transition temperature and low thermal expansion coefficient.

[0005] In a first aspect of the present application, a benzimidazole-containing polyimide is provided, wherein the benzimidazole-containing polyimide has a structural unit represented by the following formula (1):

[0006]

[0007] In each structural unit Each independently has the structure shown in the following formula (2):

[0008] R1 and R2 are independently a single bond, a C1-C4 alkylene group, a C6-C4 substituted or unsubstituted C1-C4 alkylene group, 10 Aromatic group, S2 substituted or unsubstituted C6~C 10 Heteroaromatic group or amide group; S1, S2 are independently: C6~C 10 Heteroaromatic group or S3 substituted or unsubstituted amide group; S3 is C6~C 10 Heteroaromatic groups;

[0009] In each structural unit are independently S4-substituted or unsubstituted C6-C 10 Aromatic groups;

[0010] S4 are independently: C6~C 10 Aromatic group or C6~C 10 S5 substituted with an aromatic group; S5 is n is selected from 50 to 500.

[0011] In one embodiment, R1 and R2 are independently a single bond, a C1-C4 alkylene,

[0012] In one embodiment, each structural unit Separately

[0013]

[0014] In one embodiment, each structural unit Separately Wherein R3 is selected from

[0015] In one embodiment, the structure of the benzimidazole-containing polyimide is shown in formula (3): In each structural unit, Separately

[0016] In each structural unit Separately Wherein R3 is selected from n1 is selected from 50 to 200, and m is selected from 0 to 200.

[0017] In one embodiment, the structure of the benzimidazole-containing polyimide is

[0018]

[0019] In one embodiment, the benzimidazole-containing polyimide has one or more of the following characteristics:

[0020] (1) The glass transition temperature T of the benzimidazole-containing polyimide g ≥360℃;

[0021] (2) The thermal expansion coefficient of the benzimidazole-containing polyimide is 0.8 ppm / K to 5.2 ppm / K.

[0022] In a second aspect of the present application, there is provided a method for preparing a benzimidazole-containing polyimide according to any embodiment of the first aspect of the present application, comprising the following steps:

[0023] The benzimidazole-containing diamine monomer and aromatic dianhydride monomer are used to carry out polymerization reaction in a solvent to prepare a benzimidazole-containing polyamic acid;

[0024] The benzimidazole-containing polyamic acid is subjected to an imidization reaction to prepare the benzimidazole-containing polyimide;

[0025] The structure of the benzimidazole-containing diamine monomer is shown in formula (4):

[0026]

[0027] The structure of the aromatic dianhydride monomer is shown in formula (5):

[0028]

[0029] The definition is the same as described in any embodiment of the first aspect of the present application.

[0030] In one embodiment, the benzimidazole-containing diamine monomer comprises

[0031]

[0032] One or more of .

[0033] In one embodiment, the aromatic dianhydride monomer comprises

[0034]

[0035] One or more of .

[0036] In one embodiment, the molar ratio of the benzimidazole-containing diamine monomer to the aromatic dianhydride monomer is 1:(1-1.3).

[0037] In one embodiment, the solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and N-methylpyrrolidone.

[0038] In one embodiment, the process parameters of the polymerization reaction include: the reaction temperature is -20°C to 50°C.

[0039] In one embodiment, the process parameters of the imidization reaction include one or more of a gradient temperature treatment and a constant temperature treatment;

[0040] Optionally, the process parameters of the gradient temperature rise treatment include: an end temperature of 250°C to 400°C, a heating rate of 5°C / min;

[0041] Optionally, the process parameters of the constant temperature treatment include: a reaction temperature of 250°C to 400°C.

[0042] The present invention designs the molecular formula of polyimide so that the polyimide has the advantages of high glass transition temperature and low thermal expansion coefficient. Furthermore, the preparation method of the benzimidazole-containing polyimide provided in the present invention is simple to operate and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a thermogravimetric analysis spectrum of the benzimidazole-containing polyimide film prepared in Examples 1 to 4. DETAILED DESCRIPTION

[0044] The following is a further complete and clear description of the benzimidazole-containing polyimide, the preparation method and application of the benzimidazole-containing polyimide of the present application in conjunction with specific examples. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0046] As used herein, "one or more" refers to any one, any two, or any two or more of the listed items.

[0047] In this application, "first aspect", "second aspect", "third aspect", "fourth aspect", "fifth aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", "fifth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0048] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0049] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0050] The percentage contents involved in this application, unless otherwise specified, refer to mass percentage for solid-liquid mixing and solid-solid mixing, and refer to volume percentage for liquid-liquid mixing.

[0051] The percentage concentrations mentioned in this application, unless otherwise specified, refer to the final concentration, which refers to the percentage of the added component in the system after the addition of the component.

[0052] The temperature parameters in this application, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range of instrument control.

[0053] In this application, indicates the connection site, and The number of occurrences indicates the number of junction sites.

[0054] In the present application, when a linking site is not specified in a group, it means that an optional linking site in the group can be used as a linking site.

[0055] In the present application, the single bond to which the substituent is connected runs through the corresponding ring, indicating that the substituent can be connected to any position of the ring, for example In the formula, R is connected to any substitutable position of the benzene ring. For example, Refers to a benzene ring containing 1 to 6 R functional groups. Suitable examples include, but are not limited to:

[0056] In the present application, "alkylene" refers to a hydrocarbon group with two monovalent group centers derived from an alkyl group by removing a hydrogen atom, which can be a saturated branched alkyl group or a saturated straight-chain alkyl group. For example, "C1-C4 alkylene" means that the alkyl part contains 1 to 4 carbon atoms, and each time it appears, it can be independently C1 alkylene, C2 alkylene, C3 alkylene, C4 alkylene. Suitable examples include, but are not limited to: methylene (-CH2-), 1,1-ethyl (-CH(CH3)-), 1,2-ethyl (-CH2CH2-), 1,1-propyl (-CH(CH2CH3)-), 1,2-propyl (-CH2CH(CH3)-), 1,3-propyl (-CH2CH2CH2-) and 1,4-butyl (-CH2CH2CH2CH2-).

[0057] In the present application, "aromatic group" refers to an aromatic hydrocarbon group derived from an aromatic ring compound by removing a hydrogen atom. It can be a monocyclic aromatic group, a condensed aromatic group, or a polycyclic aromatic group. For polycyclic rings, at least one is an aromatic ring system. Phrases containing this term, for example, "C6-C 10 The term "aromatic group" refers to an aromatic group containing 6 to 10 carbon atoms, and each occurrence can be independently C6 aromatic group, C7 aromatic group, C8 aromatic group, C9 aromatic group, C 10 Suitable examples include, but are not limited to, benzene and its derivatives.

[0058] In the present application, "heteroaromatic group" means that at least one carbon atom in the aromatic group is replaced by a non-carbon atom, and the non-carbon atom can be a N atom, an O atom, a S atom, etc. For example, "C6~C 10 "Heteroaryl" refers to a heteroaryl group containing 6 to 10 carbon atoms, each occurrence of which can be independently C6 heteroaryl, C7 heteroaryl, C8 heteroaryl, C9 heteroaryl, C 10 Heteroaryl. Suitable examples include, but are not limited to, furan, benzofuran, thiophene, benzothiophene, pyrrole, pyrazole, triazole, imidazole, oxazole, oxadiazole, thiazole, tetrazole, indole, carbazole, pyrroloimidazole, pyrrolopyrrole, thienopyrrole, thienothiophene, furopyrrole, furofuran, thienofuran, benzisoxazole, benzisothiazole, benzimidazole, pyridine, pyrazine, pyridazine, pyrimidine, triazine, quinoline, isoquinoline, o-naphthyridine, quinoxaline, phenanthridine, primary idine, quinazoline, and quinazolinone.

[0059] In the present application, "amide group" refers to a group containing a -C(O)N(X)2 structure, wherein "X" is independently H or alkyl; non-limiting types of amide groups include: -C(O)NH2, -C(O)NH(alkyl), -C(O)N(alkyl)2.

[0060] In a first aspect of the present application, a benzimidazole-containing polyimide is provided, wherein the benzimidazole-containing polyimide has a structural unit represented by the following formula (1):

[0061]

[0062] In each structural unit Each independently has the structure shown in the following formula (2):

[0063] R1 and R2 are independently a single bond, a C1-C4 alkylene group, a C6-C4 substituted or unsubstituted C1-C4 alkylene group, 10 Aromatic group, S2 substituted or unsubstituted C6~C 10 Heteroaromatic group or amide group; S1, S2 are independently: C6~C 10 Heteroaromatic group or S3 substituted or unsubstituted amide group; S3 is C6~C 10 Heteroaromatic groups;

[0064] In each structural unit are independently S4-substituted or unsubstituted C6-C 10 Aromatic groups;

[0065] S4 are independently: C6~C 10 Aromatic group or C6~C 10 S5 substituted with an aromatic group; S5 is n is selected from 50 to 500.

[0066] The present invention designs the molecular formula of polyimide so that the polyimide has the advantages of high glass transition temperature and low thermal expansion coefficient. Furthermore, the preparation method of the benzimidazole-containing polyimide provided in the present invention is simple to operate and easy to industrialize.

[0067] In one example, C6~C 10 The aromatic group is phenyl.

[0068] In one example, C6~C 10 The heteroaromatic group is

[0069] In one example, R1 and R2 are independently a single bond, a C1-C4 alkylene,

[0070] Preferably, R1 is selected from R2 is selected from

[0071] At this time, the polyimide contains a bibenzimidazole structure, which enables it to have a higher glass transition temperature performance, and at the same time has an amide structure, thereby ensuring that its thermal expansion coefficient is low.

[0072] In one example, the Separately

[0073] In one example, the Separately Wherein R3 is selected from

[0074] In one example, the structure of the benzimidazole-containing polyimide is shown in formula (3):

[0075] In each structural unit, Separately

[0076] In each structural unit Separately Wherein R3 is selected from n1 is selected from 50 to 200, and m is selected from 0 to 200.

[0077] In one example, the structure of the benzimidazole-containing polyimide is

[0078]

[0079] The benzimidazole-containing polyimides shown in structural formulas 1-1, 1-2 and 1-3 all contain a bibenzimidazole structure, which enables them to have a higher glass transition temperature performance, while also having an amide structure, thereby ensuring that their thermal expansion coefficient is low.

[0080] In one example, the glass transition temperature T of the benzimidazole-containing polyimide is g ≥360℃.

[0081] In one example, the thermal expansion coefficient of the benzimidazole-containing polyimide is 0.8 ppm / K to 5.2 ppm / K.

[0082] In a second aspect of the present application, there is provided a method for preparing a benzimidazole-containing polyimide according to any embodiment of the first aspect of the present application, comprising the following steps:

[0083] The benzimidazole-containing diamine monomer and aromatic dianhydride monomer are used to carry out polymerization reaction in a solvent to prepare a benzimidazole-containing polyamic acid;

[0084] The benzimidazole-containing polyamic acid is subjected to an imidization reaction to prepare the benzimidazole-containing polyimide;

[0085] The structure of the benzimidazole-containing diamine monomer is shown in formula (4):

[0086]

[0087] The structure of the aromatic dianhydride monomer is shown in formula (5):

[0088]

[0089] The definition is the same as described in any example of the first aspect of the present application.

[0090] In one example, the benzimidazole-containing diamine monomer includes

[0091]

[0092] One or more of .

[0093] Preferably, the aromatic diamine monomer is selected from By selecting the diamine monomer of this structure, the contents of benzimidazole groups and amide groups in the prepared benzimidazole-containing polyimide structure can be increased, thereby ensuring that the polyimide has an ultra-low thermal expansion coefficient.

[0094] In one example, the aromatic dianhydride monomer includes

[0095]

[0096] The present application adopts benzimidazole-containing diamine monomers and aromatic dianhydride monomers to prepare the benzimidazole-containing polyimide, which can effectively reduce the thermal expansion coefficient of the polyimide to achieve the requirement of near-zero thermal expansion, and at the same time, can ensure that the film has an excellent glass transition temperature.

[0097] In one example, the molar ratio of the benzimidazole-containing diamine monomer to the aromatic dianhydride monomer is 1:(1-1.3). It is understandable that the molar ratio of the benzimidazole-containing diamine monomer to the aromatic dianhydride monomer in the present application can be selected from any value between 1:(1-1.3). Specifically, the molar ratio of the benzimidazole-containing diamine monomer to the aromatic dianhydride monomer includes but is not limited to 1:1, 1:1.15, 1:1.2, 1:1.24, 1:1.25, 1:1.26 or 1:3.

[0098] In one example, the solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone. In the present application, the solvent is preferably an aprotic solvent, more preferably N,N-dimethylacetamide or N-methylpyrrolidone. In the present application, there is no special limitation on the amount of the solvent, as long as the solid content of the system (i.e., the total mass of the dianhydride monomer and the diamine monomer) is 8 to 30%.

[0099] In one example, the polymerization reaction is carried out under a protective atmosphere. It is understandable that the present application has no special limitation on the protective atmosphere, and a protective atmosphere well known in the art can be used, such as nitrogen or argon.

[0100] In one example, the process parameters of the polymerization reaction include: a reaction temperature of -20°C to 50°C. It is understandable that the reaction temperature of the polymerization reaction can be selected from any value between -20°C and 50°C. Specifically, the reaction temperature of the polymerization reaction includes but is not limited to -20°C, -10°C, 0°C, 10°C, 15°C, 20°C, 25°C, 26°C, 30°C, 40°C or 50°C.

[0101] In one example, the process parameters of the polymerization reaction include: a reaction time of 5 h to 10 h. It is understandable that the reaction time of the polymerization reaction can be selected from any value between 5 h and 10 h. Specifically, the reaction time of the polymerization reaction includes but is not limited to 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 9 h or 10 h.

[0102] In the present application, in the process of polymerizing the benzimidazole-containing diamine monomer and the aromatic dianhydride monomer in a solvent, the method of mixing the benzimidazole-containing diamine monomer, the aromatic dianhydride monomer and the solvent is not limited. The mixing method is preferably to first add the benzimidazole-containing diamine monomer to the solvent, and then add the aromatic dianhydride monomer. The polymerization reaction is preferably accompanied by stirring, that is, the polymerization reaction is carried out under continuous stirring. After the polymerization reaction, a uniform and viscous polyamic acid solution is formed.

[0103] In one example, the imidization reaction is carried out under a protective atmosphere. It is understandable that the present application has no particular limitation on the protective atmosphere, and a protective atmosphere well known in the art, such as nitrogen or argon, can be used.

[0104] In one example, the treatment conditions of the imidization reaction are selected from one or more of gradient temperature treatment or constant temperature treatment.

[0105] In one example, the imidization reaction is performed in a muffle furnace.

[0106] In one example, the process parameters of the gradient temperature increase treatment include: an end point temperature of 250°C to 400°C, and a heating rate of 5°C / min.

[0107] In one specific example, the step of the gradient temperature treatment includes: heating to 200℃~280℃ at a heating rate of 5℃ / min, keeping warm for 1h~2h; heating to 300℃~360℃ in half an hour, keeping warm for 1h~2h; heating to 380℃~400℃ in the next half an hour, keeping warm for 0.5h~1h. Carrying out the imidization reaction by the gradient temperature treatment is beneficial to increase the glass transition temperature of the benzimidazole-containing polyimide, reduce the thermal expansion coefficient, and make it have good mechanical properties.

[0108] In one example, the process parameters of the gradient temperature increase treatment include: a holding time of 2 to 5 hours.

[0109] In one example, the process parameters of the constant temperature treatment include: a reaction temperature of 250°C to 400°C.

[0110] In one example, the process parameters of the constant temperature treatment include: a holding time of 2 to 5 hours.

[0111] According to a third aspect of the present application, a benzimidazole-containing polyimide film is provided, wherein the material of the benzimidazole-containing polyimide film is the benzimidazole-containing polyimide described in any one of the embodiments of the first aspect of the present application.

[0112] In one example, the thermal expansion coefficient of the benzimidazole-based polyimide film described in the present application is 0.8 ppm / K to 5.2 ppm / K.

[0113] In one example, the glass transition temperature of the benzimidazole-based polyimide film described in the present application is 360°C to 500°C.

[0114] In a fourth aspect of the present application, there is provided a method for preparing the benzimidazole-containing polyimide film according to the third aspect of the present application, comprising the following steps:

[0115] The benzimidazole-containing diamine monomer and the aromatic dianhydride monomer are polymerized in a solvent to prepare a benzimidazole-containing polyamic acid;

[0116] The benzimidazole-containing polyamic acid is subjected to imidization reaction after casting and curing to prepare the benzimidazole-containing polyimide film.

[0117] It can be understood that in the preparation method of the benzimidazole-containing polyimide film described in the fourth aspect of the present application, the benzimidazole-containing diamine monomer and aromatic dianhydride monomer used are the same as the benzimidazole-containing diamine monomer and aromatic dianhydride monomer used in the second aspect of the present application, and the parameters of the polymerization reaction and the imidization reaction are also the same, which will not be repeated here.

[0118] In one example, a benzimidazole-containing diamine monomer and an aromatic dianhydride monomer are polymerized in a solvent to prepare a benzimidazole-containing polyamic acid, and a degassing treatment is also included. The present application has no special restrictions on the degassing treatment method, and it can be a conventional degassing treatment method in the art, such as standing treatment or vacuum treatment. The degassing treatment step can be exemplified by standing the benzimidazole-containing polyamic acid in a refrigerator to degas. After the above-mentioned degassing treatment, the subsequent process is carried out.

[0119] It is understandable that the present application has no particular restrictions on the mode of casting, and can adopt direct casting film forming or biaxial stretching film forming after casting.Wherein, the mode of biaxial stretching has no particular restrictions, and is a conventional biaxial stretching method well known to those skilled in the art.The operating mode of the casting has no particular restrictions, and is a conventional casting film-making mode in the art, and can be exemplified by flowing the benzimidazole-containing polyamic acid to a substrate to form a liquid film.In the present application, the type of the substrate has no particular restrictions, and is a conventional substrate for preparing thin films in the art, including smooth substrates such as glass plates, metal plates, silicon substrates or polytetrafluoroethylene plates, preferably glass plates.

[0120] In one example, the curing process parameters include: a curing temperature of 50° C. to 120° C. and a curing time of 6 h to 12 h.

[0121] In one example, the imidization reaction is carried out under a protective atmosphere. It is understandable that the present application has no particular limitation on the protective atmosphere, and a protective atmosphere well known in the art, such as nitrogen or argon, can be used.

[0122] In one example, after the step of performing the imidization reaction, the step of peeling off the benzimidazole-containing polyimide film is also included. The present application does not specifically limit the method of peeling off the benzimidazole-containing polyimide film, and the method of peeling off the film well known in the art can be used. The process parameters of the peeling can be exemplified as: putting it into deionized water at 15°C to 60°C for peeling to obtain a benzimidazole-containing polyimide film.

[0123] In one specific example, the method for preparing the benzimidazole-containing polyimide film comprises the following steps:

[0124] The benzimidazole-containing diamine monomer and the aromatic dianhydride monomer are polymerized in a solvent under a protective atmosphere, wherein the process parameters of the polymerization reaction are: a reaction temperature of -20°C to 50°C, and a reaction time of 5h to 10h; a benzimidazole-containing polyamic acid is prepared; and the benzimidazole-containing polyamic acid is allowed to stand to remove bubbles;

[0125] The defoamed benzimidazole-containing polyamic acid is flowed onto a substrate to form a liquid film, and the liquid film is solidified, the solidification temperature is 50°C to 120°C, and the solidification time is 6h to 12h; after solidification, an imidization reaction is carried out, and the process parameters of the imidization reaction include: an end temperature of 250°C to 400°C, a heating rate of 5°C / min, and a heat preservation time of 2 to 5h. After the imidization reaction is completed, it is naturally cooled; the substrate is placed in deionized water at room temperature, and the film is peeled off to prepare the benzimidazole-containing polyimide film.

[0126] The fifth aspect of the present application provides an application of the benzimidazole-containing polyimide described in any embodiment of the first aspect of the present application and the benzimidazole-containing polyimide film described in any embodiment of the third aspect of the present application in the nuclear field.

[0127] The polyimide provided in the present application contains a benzimidazole group, which enables it to have a higher glass transition temperature and a lower thermal expansion coefficient, and can meet the requirements of the nuclear field for a high glass transition temperature and a low linear expansion coefficient.

[0128] The following are specific examples. Unless otherwise specified, the raw materials used in the examples are all commercially available products.

[0129] Example 1

[0130] The structural formula of the benzimidazole-containing polyimide prepared in Example 1 is shown in Formula 1-1, wherein n is 100 to 110, and specifically comprises the following steps:

[0131]

[0132] Weigh 10.00g 1H,1'H-(5,6'-bibenzimidazole)-2,2'-(4-aminobenzamide) and 5.85g biphenyl dianhydride into a 250ml three-necked round-bottom flask, add 63.4g N,N-dimethylacetamide, and introduce nitrogen. Perform mechanical stirring. After reacting for 6 to 8 hours, a benzimidazole-containing polyamic acid reaction liquid is prepared, and the reaction liquid is placed in a refrigerator to remove bubbles.

[0133] The reaction solution is cast on a clean glass plate, and the wet film is placed in an oven at 80°C for 8 to 10 hours to remove most of the solvent, and then the film is transferred to a vacuum muffle furnace with a programmed temperature rise. The thermal imide heating program is 200°C for 1 hour (heating rate is 5°C / min), heated to 300°C for half an hour, kept warm for 1 hour, heated to 380°C for half an hour, kept warm for half an hour, and the thermal imide is finished, and cooled naturally. The glass plate is placed in deionized water at room temperature, and the film is gradually peeled off from the glass plate automatically, and the benzimidazole-containing polyimide film is taken out and vacuum dried.

[0134] Example 2

[0135] The structural formula of the benzimidazole-containing polyimide prepared in Example 2 is shown in Formula 1-2, wherein n is 50 to 60, and m is 50 to 60, and specifically comprises the following steps:

[0136]

[0137] Weigh 5.00g 1H,1'H-(5,6'-bibenzimidazole)-2,2'-(4-aminobenzamide), 3.38g 2,2'-(1,4-phenylene)bis(1H-benzimidazole-5-amine) and 5.85g biphenyl dianhydride into a 250ml three-necked round-bottom flask, add 95.23g N,N-dimethylacetamide, introduce nitrogen, and stir mechanically. After reacting for 6 to 8 hours, a benzimidazole-containing polyamic acid reaction liquid is prepared, and the reaction liquid is placed in a refrigerator to remove bubbles.

[0138] The reaction solution is cast on a clean glass plate, and the wet film is placed in an oven at 80°C for 8 to 10 hours to remove most of the solvent, and then the film is transferred to a vacuum muffle furnace with a programmed temperature rise. The thermal imide heating program is 200°C for 1 hour (heating rate is 5°C / min), heated to 300°C for half an hour, kept warm for 1 hour, heated to 380°C for half an hour, kept warm for half an hour, and the thermal imide is finished, and cooled naturally. The glass plate is placed in deionized water at room temperature, and the film is gradually peeled off from the glass plate automatically, and the benzimidazole-containing polyimide film is taken out and vacuum dried.

[0139] Example 3

[0140] The structure of the benzimidazole-containing polyimide prepared in Example 3 is shown in Formula 1-3, wherein n is 50 to 60, and m is 50 to 60, and specifically comprises the following steps:

[0141]

[0142] Weigh 5.00g 1H,1'H-(5,6'-bibenzimidazole)-2,2'-(4-aminobenzamide), 2.23g 2-(4-aminophenyl)-1H-benzimidazole-5-amine and 5.85g biphenyl dianhydride into a 250ml three-necked round-bottom flask, add 74.12g N,N-dimethylacetamide, introduce nitrogen, and stir mechanically. After reacting for 6 to 8 hours, a benzimidazole-containing polyamic acid reaction liquid is prepared, and the reaction liquid is placed in a refrigerator to remove bubbles.

[0143] Example 4

[0144] The structure of the benzimidazole-containing polyimide prepared in Example 4 is shown in Formula 1-4, wherein n is 50 to 60, and specifically comprises the following steps:

[0145]

[0146] Weigh 5.00g of 4-amino-N-(5-amino-1-methylbenzimidazole-2-yl)-benzamide and 5.85g of biphenyl dianhydride into a 250ml three-necked round-bottom flask, add 50g of N,N-dimethylacetamide, and introduce nitrogen. Perform mechanical stirring. After reacting for 6 to 8 hours, a benzimidazole-containing polyamic acid reaction liquid is prepared, and the reaction liquid is placed in a refrigerator to remove bubbles.

[0147] The reaction solution is cast on a clean glass plate, and the wet film is placed in an oven at 80°C for 8 to 10 hours to remove most of the solvent, and then the film is transferred to a vacuum muffle furnace with a programmed temperature rise. The thermal imide heating program is 200°C for 1 hour (heating rate is 5°C / min), heated to 300°C for half an hour, kept warm for 1 hour, heated to 380°C for half an hour, kept warm for half an hour, and the thermal imide is finished, and cooled naturally. The glass plate is placed in deionized water at room temperature, and the film is gradually peeled off from the glass plate automatically, and the benzimidazole-containing polyimide film is taken out and vacuum dried.

[0148] The reaction solution is cast on a clean glass plate, and the wet film is placed in an oven at 80°C for 8 to 10 hours to remove most of the solvent, and then the film is transferred to a vacuum muffle furnace with a programmed temperature rise. The thermal imide heating program is 200°C for 1 hour (heating rate is 5°C / min), heated to 300°C for half an hour, kept warm for 1 hour, heated to 380°C for half an hour, kept warm for half an hour, and the thermal imide is finished, and cooled naturally. The glass plate is placed in deionized water at room temperature, and the film is gradually peeled off from the glass plate automatically, and the benzimidazole-containing polyimide film is taken out and vacuum dried.

[0149] The thermal expansion coefficient of the polyimide film containing benzimidazole groups prepared in Examples 1 to 4 was tested by using a static thermomechanical analyzer TA Q400 in a nitrogen atmosphere at a heating rate of 5°C / min and a test temperature range of room temperature to 400°C. The results are shown in Table 1. The thermal gravimetric analysis of the polyimide film containing benzimidazole groups prepared in Examples 1 to 4 was performed using a thermogravimetric analyzer. The results are shown in Table 1. Figure 1 And as shown in Table 1.

[0150] The coefficient of thermal expansion (CTE) of Examples 1 to 3 in the temperature range of 50°C to 300°C is respectively obtained. Figure 1 And as shown in Table 1.

[0151] Table 1 Performance test results of benzimidazole-containing polyimide films

[0152] project T5％(℃) Tg(℃) CTE(ppm / k) Example 1 450 373 1.08 Example 2 503 445 5.01 Example 3 494 388 3.77 Example 4 450 363 3.70

[0153] From Table 1 and Figure 1 It can be seen that the 5wt% thermal weight loss temperature of the benzimidazole-containing polyimide film prepared in Examples 1 to 4 of the present application is 450°C to 503°C, the glass transition temperature is 373°C to 445°C, and the thermal expansion coefficient is 1.08ppm / K to 5.01ppm / K, indicating that the benzimidazole-containing polyimide film prepared in the present application has excellent thermal stability, a low thermal expansion coefficient, and a high glass transition temperature.

[0154] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0155] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A benzimidazole-containing polyimide, characterized in that: The benzimidazole-containing polyimide has a structure as shown in the following formula (1-1): ； n is selected from 50~500.

2. The benzimidazole-containing polyimide according to claim 1, characterized in that: The glass transition temperature T g ≥360℃.

3. The benzimidazole-containing polyimide according to claim 1 or 2, characterized in that: The thermal expansion coefficient of the benzimidazole-containing polyimide is 0.8 ppm / K to 5.2 ppm / K.

4. A method for preparing a benzimidazole-containing polyimide according to any one of claims 1 to 3, characterized in that: The following steps are involved: The benzimidazole-containing diamine monomer and aromatic dianhydride monomer are used to carry out polymerization reaction in a solvent to prepare a benzimidazole-containing polyamic acid; The benzimidazole-containing polyamic acid is subjected to an imidization reaction to prepare the benzimidazole-containing polyimide; The structure of the benzimidazole-containing diamine monomer is: ； The structure of the aromatic dianhydride monomer is: .

5. The method for preparing a benzimidazole-containing polyimide according to claim 4, wherein: The molar ratio of the benzimidazole-containing diamine monomer to the aromatic dianhydride monomer is 1:(1-1.3).

6. The method for preparing the benzimidazole-containing polyimide according to claim 4 or 5, characterized in that: The solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and N-methylpyrrolidone.

7. The method for preparing a benzimidazole-containing polyimide according to claim 4 or 5, characterized in that: The process parameters of the polymerization reaction include: the reaction temperature is -20°C to 50°C.

8. The method for preparing a benzimidazole-containing polyimide according to claim 4 or 5, characterized in that: The process parameters of the imidization reaction include one or more of a gradient temperature treatment and a constant temperature treatment.

9. The method for preparing a benzimidazole-containing polyimide according to claim 8, characterized in that: The process parameters of the gradient temperature increase treatment include: an end temperature of 250°C to 400°C, and a heating rate of 5°C / min.

10. The method for preparing a benzimidazole-containing polyimide according to claim 8, characterized in that: The process parameters of the constant temperature treatment include: the reaction temperature is 250°C to 400°C.

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