Polyimide containing pyridine structure and preparation method and application thereof

Abstract

The invention provides polyimide containing a pyridine structure as well as a preparation method and application of the polyimide. The structural formula of the polyimide is shown as a formula (II) or a formula (III): in the formula (II) # imgabs0 #, m and n are positive integers, and n is greater than or equal to 10 and greater than or equal to m; and the # imgabs 1 # group is a fluorine-containing phenyl group. According to the polyimide shown in the formula (II), a large-volume group and trifluoromethyl are introduced, meanwhile, hydroxyl is introduced, polyimide platformization is achieved, and possibility is provided for subsequent introduction of other different groups; in the imidization process, a chemical imidization method and a thermal imidization method are combined, and compared with a traditional method, the time needed by imidization is shortened. The polyimide introduced with hydroxyl and shown in the formula (II) obviously reduces the dielectric constant; according to the polyimide shown in the formula (III), a fluorobenzene structure is introduced on the basis of the polyimide shown in the formula (II), and the dielectric constant of the polyimide is further reduced.

Description

Technical Field

[0001] The invention relates to the field of organic materials, and in particular to a polyimide containing a pyridine structure and a preparation method and application thereof. Background Art

[0002] With the advent of the 5G era, microelectronic devices are becoming increasingly miniaturized and multifunctional, which has led to a series of problems such as poor diffraction ability of electromagnetic wave signals, increased signal transmission attenuation, increased parasitic resistance effect in circuits, and increased capacitance effect. These problems have seriously affected the performance of electronic components. Therefore, it is particularly urgent to explore ways to reduce the dielectric constant of materials.

[0003] The dielectric constant of traditional polyimide (PI) is about 3.0, and the methods for reducing the dielectric constant of PI mainly include introducing bulky groups, CF bonds or fluorinated diamines or dianhydrides. These methods have achieved results to a certain extent, as shown in patent documents such as CN1580095A, CN112646182A, CN113248709A and CN115433121A. However, these methods have a long imidization time, and even after improvement, the dielectric constant can only be reduced to about 2.5. Such performance improvement obviously cannot meet the urgent demand for lower dielectric constant materials in the advanced electronics field.

[0004] Therefore, developing a new type of polyimide material with a lower dielectric constant to meet the high requirements of material performance for microelectronic devices in the 5G era has become a technical problem that needs to be solved urgently.

[0005] Therefore, methods to introduce bulky groups and CF bonds into PIs are urgently needed to meet the increasingly urgent technological demands in the field of advanced electronics. Summary of the invention

[0006] The object of the present invention is to provide a polyimide containing a pyridine structure and a preparation method thereof.

[0007] The present invention provides a polyimide containing a pyridine structure, the structural formula of which is shown in formula (II):

[0008]

[0009] In formula (II), m and n are positive integers, and m≥n≥10.

[0010] The present invention also provides a method for preparing the polyimide represented by formula (II), comprising the following steps:

[0011] S1, condensing the diamine monomer represented by formula (I), 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB) and bisphenol A diether dianhydride to obtain polyamic acid;

[0012]

[0013] S2. Add a dehydrating agent and a catalyst to imidize the polyamic acid to obtain polyimide.

[0014] Furthermore, in step S1, the condensation reaction temperature is 15-30°C; in step S2, the imidization temperature is 170-190°C.

[0015] Among them, a method for preparing a diamine monomer represented by formula (I) comprises the following steps:

[0016] Under an inert gas atmosphere, p-hydroxybenzaldehyde, p-nitroacetophenone and ammonium acetate are added to a solvent and reacted at 110-125° C. After the reaction is completed, the reaction solution is filtered, dried and recrystallized to obtain an intermediate represented by formula (A):

[0017]

[0018] The intermediate represented by formula (A) and hydrazine hydrate are reacted with palladium-carbon catalyst under the protection of inert gas at 70-80°C; after the reaction is completed, the reaction is filtered, the filter cake is dissolved with a solvent, and the catalyst is removed by filtering again, and the filtrate is added dropwise to deionized water to obtain the diamine monomer represented by formula (I).

[0019] For example, the inert gas may be nitrogen, argon, helium, etc.

[0020] Furthermore, the molar ratio of p-hydroxybenzaldehyde, p-nitroacetophenone and ammonium acetate is 1:(2-2.5):(12-14).

[0021] The present invention also provides another polyimide containing a pyridine structure, wherein the general structural formula of the polyimide is as shown in formula (III):

[0022]

[0023] in: The group is a fluorinated phenyl group.

[0024] According to a specific embodiment of the present invention, The group is selected from the structure shown in formula (B1), formula (B2) or formula (B3):

[0025]

[0026] The present invention also provides a method for preparing a polyimide represented by formula (III), comprising the following steps:

[0027] In a nitrogen atmosphere, in the presence of an alkaline substance, the polyimide represented by formula (II) reacts with fluorine-containing benzoyl chloride to obtain the polyimide represented by formula (III).

[0028] The present invention also provides a polyimide film, wherein the polyimide in the film is a polyimide represented by formula (II) and / or a polyimide represented by formula (III).

[0029] The present invention also provides a method for preparing a polyimide film, comprising dissolving a polyimide represented by formula (II) and / or a polyimide represented by formula (III) in a solvent, filtering the solution through a filter membrane, and then spin-coating the solution onto a glass plate; drying the spin-coated glass to remove the solvent in the coating so that the polyimide is solidified into a film; and placing the dried glass plate in deionized water to peel off the polyimide film from the glass plate, thereby obtaining a polyimide film.

[0030] Compared with the prior art, the present invention has the following advantages: This technology introduces hydroxyl groups into polyimide while introducing bulky groups and CF bonds. The introduction of hydroxyl groups makes it possible to introduce other different groups after the synthesis of polyimide, explore the effects of different groups on the dielectric properties of polyimide, and realize the platformization of polyimide. The polyimide shown in formula (II) combines the chemical imide method and the thermal imide method in the imidization process, which shortens the time required for imidization compared to traditional methods. The polyimide shown in formula (II) introduces hydroxyl groups while introducing bulky groups and trifluoromethyl groups, realizing the platformization of polyimide, which provides the possibility for the subsequent introduction of other different groups, so that the effects of different groups on the dielectric properties and other physical properties of polyimide can be more comprehensively explored. This platform design makes the modification space of polyimide broader and provides the possibility for customized design of high-performance materials (such as improving heat resistance, enhancing mechanical properties, etc.). The polyimide of formula (II) with the introduction of hydroxyl group significantly reduces the dielectric constant; the polyimide of formula (III) introduces a fluorobenzene structure based on the polyimide of formula (II), thereby further reducing the dielectric constant of the polyimide.

[0031] In summary, the present invention provides a new idea and method for preparing high-performance polyimide materials by innovatively combining multi-element modification, improving imidization efficiency, effectively reducing dielectric constant, and realizing multifunctionality and customization potential. It has significant technical advantages and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0033] Figure 1 is the nuclear magnetic hydrogen spectrum of the diamine monomer represented by formula (I) of the present invention;

[0034] Figure 2 is the nuclear magnetic hydrogen spectrum of the polyimide represented by formula (II) of the present invention;

[0035] Figure 3 is the nuclear magnetic hydrogen spectrum of the polyimide represented by formula (III-B1) of the present invention;

[0036] Figure 4 It is the nuclear magnetic resonance fluorine spectrum of the polyimide represented by formula (III-B1) of the present invention.

[0037] Figure 5 is the nuclear magnetic hydrogen spectrum of the polyimide represented by formula (III-B2) of the present invention;

[0038] Figure 6 It is the nuclear magnetic fluorine spectrum of the polyimide represented by formula (III-B2) of the present invention.

[0039] Figure 7 is the nuclear magnetic hydrogen spectrum of the polyimide represented by formula (III-B3) of the present invention;

[0040] Figure 8 It is the nuclear magnetic fluorine spectrum of the polyimide represented by formula (III-B3) of the present invention. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the technical solutions in this application, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of this application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should belong to the scope of protection of this application. Unless otherwise specified, the percentages of the present invention refer to mass percentages.

[0042] The diamine monomer represented by formula (I) of the present invention contains a pyridine structure, and its preparation method comprises the following steps:

[0043] 1) p-Hydroxybenzaldehyde, p-nitroacetophenone and ammonium acetate are used as raw materials and acetic acid is used as solvent; under a nitrogen atmosphere, p-Hydroxybenzaldehyde, p-nitroacetophenone and ammonium acetate are added to the solvent in a molar ratio of 1:(2-2.5):(12-14), stirred and heated, and reacted at 125° C. for 12 hours; after the reaction is completed, the reaction liquid is filtered, the filter cake is repeatedly washed with acetic acid for multiple times, filtered, dried and recrystallized to obtain an intermediate represented by formula (A).

[0044] The reaction equation of the above process is as follows:

[0045]

[0046] 2) Using ethanol as solvent; under nitrogen atmosphere, adding the intermediate represented by formula (A) and Pd / C catalyst into the solvent, stirring, slowly dropping hydrazine hydrate, heating to 80° C. and reacting for 8 to 12 hours after the dropping is complete; after the reaction is complete, filtering the reaction liquid, dissolving the filter cake with N,N-dimethylformamide (DMF) and filtering to remove Pd / C, and slowly dropping the filtrate into deionized water to obtain the diamine monomer represented by formula (I).

[0047] The reaction equation of the above process is as follows:

[0048]

[0049] The polyimide of formula (II) containing a pyridine structure of the present invention is prepared by polymerizing a diamine monomer of formula (I), 6FAPB and BPADA, and the preparation method comprises the following steps:

[0050] S1. Accurately weigh the dried diamine monomer and 6FAPB of formula (Ⅰ), add them into a dry three-necked flask under nitrogen atmosphere, add solvent and stir to dissolve the diamine monomer and 6FAPB, then add the dried dianhydride monomer, wherein the molar ratio of the diamine monomer, 6FAPB and dianhydride of formula (Ⅰ) is preferably controlled at 1:1:2, and rinse the bottle mouth with solvent. Stir the reaction at 15-30℃ for 20-30h; the reaction liquid is light yellow and transparent with high viscosity. In step S1, the solvent is anhydrous N-methylpyrrolidone (NMP).

[0051] S2. Add a catalyst and a dehydrating agent to the reaction solution of S1, and continue stirring at 180°C for 3 to 4 hours. Terminate the reaction, slowly add the reaction solution to ethanol for washing, and the solid precipitates into a light yellow powder. Filter and dry to obtain a light yellow powder solid, which is the polyimide represented by formula (II). The catalyst can be pyridine, and the dehydrating agent can be γ-valerolactone.

[0052] The reaction equation of the above process is as follows:

[0053]

[0054] The polyimide of formula (III) containing fluorine and pyridine structure of the present invention is prepared by reacting the polyimide of formula (II) with fluorobenzoyl chloride. The preparation method comprises the following steps:

[0055] In a nitrogen atmosphere, a polyimide represented by formula (II) and cesium carbonate are added to a solvent; tetrahydrofuran (THF) is used as the solvent; after stirring until the polyimide represented by formula (II) is completely dissolved, fluorobenzoyl chloride is slowly added dropwise in an ice-water bath, and after the addition is completed, the reaction is carried out at room temperature for 10 hours. After the reaction is completed, the reaction solution is added dropwise to ethanol and water for washing, and a solid is precipitated into a powder, which is filtered and dried to obtain a powdery solid, namely the polyimide represented by formula (III).

[0056] The reaction equation of the above process is as follows:

[0057]

[0058] The polyimide represented by formula (II) and the polyimide represented by formula (III) obtained above can be used to prepare a polyimide film. The preparation method is: dissolve the polyimide represented by formula (II) and / or the polyimide represented by formula (III) in a solvent, filter through a filter membrane and then spin-coat it onto a glass plate, place the glass plate in a vacuum oven, heat at 60°C, 120°C, 180°C, 240°C, and 300°C for 20 minutes respectively, finally place the glass plate in deionized water, peel off the film, and obtain a polyimide film.

[0059] Example 1

[0060] 1) Preparation process of diamine monomer represented by formula (I):

[0061] Add 225mL of anhydrous acetic acid to a dry 500mL three-necked flask, add 100mmol of p-hydroxybenzaldehyde, 205mmol of p-nitroacetophenone, and 1430mmol of ammonium acetate under magnetic stirring, heat to 125°C under nitrogen, and stir to react for 12 hours. Filter the reaction solution, wash the obtained solid with acetic acid until the filtrate is colorless, filter and dry to obtain 17.3g of light yellow solid, with a yield of 41.8%, which is the crude nitro product; then recrystallize the crude nitro product with DMF, m (crude nitro product): V (DMF) = 1:5, the recrystallization temperature is 150°C, filter and dry to obtain 15.6g of pure nitro product, with a yield of 90.2%, which is the intermediate shown in formula (A).

[0062] In a dry 500mL three-necked flask, add 24mmol of the intermediate represented by formula (A), 200ml of anhydrous ethanol, 1g of Pd / C catalyst (active ingredient 5%) under nitrogen atmosphere, and add 40ml of hydrazine hydrate dropwise with stirring (hydrazine hydrate is slowly dripped into the dropping funnel for 30min). After the addition of hydrazine hydrate is completed, heat to 80°C and stir under reflux for 12h. After the reaction is completed, filter to obtain a mixture of Pd / C and the diamine monomer represented by formula (Ⅰ), add 80ml of DMF to the mixture to dissolve the diamine monomer represented by formula (Ⅰ), filter to remove Pd / C, slowly add the filtrate to 1500ml of deionized water for washing, filter the solid precipitate to obtain 7.6g of light yellow solid product, with a yield of 88.9%. The light yellow solid product is the diamine monomer represented by formula (Ⅰ), and its nuclear magnetic hydrogen spectrum is shown in Figure 1 .

[0063] 2) Preparation process of polyimide shown in formula (II):

[0064] Accurately weigh 10mmol of the dried diamine monomer of formula (Ⅰ), 10mmol of 6FAPB, and 80mL of anhydrous NMP, add them into a dry 250ml three-necked flask, stir mechanically under a nitrogen atmosphere to dissolve all the solids, then add 20mmol of the dried dianhydride monomer BPADA, and measure 20mL of anhydrous NMP to rinse the bottle mouth. Stir and react at room temperature of 26℃ for 24 hours. The reaction liquid is light yellow and transparent, with a high viscosity; add 4.0mL of pyridine as a catalyst, add 800mg of γ-valerolactone as a dehydrating agent, and continue stirring and reacting at 180℃ for 4 hours under a nitrogen atmosphere. Terminate the reaction, slowly add the reaction liquid into 1000ml of ethanol for washing, and the solid precipitates into a light yellow powder. Filter and dry to obtain 15.5g of a light yellow powder solid with a yield of 88.6%. The light yellow powder solid is the polyimide of formula (Ⅱ), and its nuclear magnetic hydrogen spectrum is shown in Figure 2 .

[0065] 3) Preparation process of polyimide represented by formula (III-B1):

[0066] Accurately weigh 2mmol of the dried polyimide of formula (II), 1.5mmol of cesium carbonate, and 20ml of anhydrous THF, add them into a dry 100ml double-necked flask, stir under a nitrogen atmosphere to completely dissolve the polyimide of formula (II), accurately weigh 1.5mmol of 4-fluorobenzoyl chloride, and slowly drop it into the solution under an ice-water bath. After the dropwise addition is completed, stir the reaction for 10 hours. Terminate the reaction, slowly add the reaction solution into a mixed solution of 500ml ethanol and 100ml water for washing, and the solid precipitates into a powder. Filter and dry to obtain 3.11g of a powdery solid with a yield of 83.0%. The powdery solid is the polyimide of formula (III-B1), and its nuclear magnetic hydrogen spectrum is shown in Figure 3 , NMR fluorine spectrum see Figure 4 .

[0067]

[0068] 4) Accurately weigh 2 g of the dried polyimide represented by formula (II) and 2 g of the polyimide represented by formula (III-B1), dissolve them in 12 g of N,N-dimethylacetamide (DMAc) with a solid content of 25%, filter through a filter membrane and spin coat them onto a glass plate at a speed of 500 r / min for 30 seconds; place the glass plate in a vacuum oven and heat them at 60°C, 120°C, 180°C, 240°C and 300°C for 20 minutes respectively; finally, place the glass plate in deionized water, peel off the film, and obtain a polyimide film. The dielectric properties of the obtained polyimide film are shown in Table 1 below.

[0069] Embodiment 2:

[0070] 1) Preparation process of diamine monomer represented by formula (Ⅰ): same as that of Example 1.

[0071] 2) Preparation process of polyimide represented by formula (II): same as that of implementation example 1.

[0072] 3) Preparation process of polyimide represented by formula (III-B2):

[0073] Accurately weigh 2mmol of the dried polyimide of formula (II), 1.5mmol of cesium carbonate, and 20ml of anhydrous THF, add them into a dry 100ml double-necked flask, stir under a nitrogen atmosphere to dissolve all the polyimide of formula (II), accurately weigh 1.5mmol of 3,4,5-trifluorobenzoyl chloride, and slowly drop it into the solution under an ice-water bath. After the addition is completed, stir the reaction for 10 hours. Terminate the reaction, slowly add the reaction solution into a mixed solution of 500ml ethanol and 100ml water for washing, and the solid precipitates into a powder. Filter and dry to obtain 3.19g of powdery solid with a yield of 83.5%. The powdery solid is the polyimide of formula (III-B2), and its nuclear magnetic hydrogen spectrum is shown in Figure 5 , NMR fluorine spectrum see Figure 6 .

[0074]

[0075] 4) Accurately weigh 2 g of the dried polyimide represented by formula (III-B2), dissolve it in 6 g of N,N-dimethylacetamide (DMAc) with a solid content of 25%, filter it through a filter membrane, and then spin-coat it onto a glass plate at a speed of 500 r / min for 30 seconds; place the glass plate in a vacuum oven, and heat it at 60°C, 120°C, 180°C, 240°C, and 300°C for 20 minutes respectively; finally, place the glass plate in deionized water, peel off the film, and a polyimide film can be obtained. The dielectric properties of the obtained polyimide film are shown in Table 1 below.

[0076] Embodiment 3:

[0077] 1) Preparation process of diamine monomer represented by formula (Ⅰ): same as that of Example 1.

[0078] 2) Preparation process of polyimide represented by formula (II): same as that of implementation example 1.

[0079] 3) Preparation process of polyimide represented by formula (III-B3):

[0080] Accurately weigh 2mmol of the dried polyimide of formula (II), 1.5mmol of cesium carbonate, and 20ml of anhydrous THF, add them into a dry 100ml double-necked flask, stir under a nitrogen atmosphere to dissolve all the polyimide of formula (II), accurately weigh 1.5mmol of 2,3,4,5,6-pentafluorobenzoyl chloride, and slowly drop it into the solution under an ice-water bath. After the addition is completed, stir the reaction for 10 hours. Terminate the reaction, slowly add the reaction solution into a mixed solution of 500ml ethanol and 100ml water for washing, and the solid precipitates into a powder. Filter and dry to obtain 3.20g of a powdery solid with a yield of 82.3%. The powdery solid is the polyimide of formula (III-B3), and its nuclear magnetic hydrogen spectrum is shown in Figure 7 , NMR fluorine spectrum see Figure 8 .

[0081]

[0082] 4) Accurately weigh 2 g of the dried polyimide represented by formula (III-B3), dissolve it in 6 g of N,N-dimethylacetamide (DMAc) with a solid content of 25%, filter it through a filter membrane, and then spin-coat it onto a glass plate at a speed of 500 r / min for 30 seconds; place the glass plate in a vacuum oven, and heat it at 60°C, 120°C, 180°C, 240°C, and 300°C for 20 minutes respectively; finally, place the glass plate in deionized water, peel off the film, and a polyimide film can be obtained. The dielectric properties of the obtained polyimide film are shown in Table 1 below.

[0083]

Claims

1. A polyimide containing a pyridine structure, characterized in that: The structural formula of the polyimide is shown in formula (II) or formula (III): In formula (II), m and n are positive integers, and m≥n≥10; in: The group is a fluorinated phenyl group.

2. The polyimide according to claim 1, characterized in that The group is selected from the structure shown in formula (B1), formula (B2) or formula (B3):

3. A method for preparing the polyimide containing a pyridine structure according to claim 1, characterized in that: The steps include: S1, condensing the diamine monomer represented by formula (I), 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB) and bisphenol A diether dianhydride to obtain polyamic acid; S2. Add a dehydrating agent and a catalyst to imide the polyamic acid to obtain a polyimide represented by formula (II).

4. The preparation method according to claim 3, characterized in that: In step S1, the condensation reaction temperature is 15-30°C; in step S2, the imidization temperature is 170-190°C.

5. The preparation method according to any one of claims 3 to 4, characterized in that: The preparation method of the diamine monomer represented by formula (I) comprises the following steps: Under an inert gas atmosphere, p-hydroxybenzaldehyde, p-nitroacetophenone and ammonium acetate are added to a solvent and reacted at 110-125° C. After the reaction is completed, the reaction solution is filtered, dried and recrystallized to obtain an intermediate represented by formula (A): The intermediate represented by formula (A) and hydrazine hydrate are reacted with palladium-carbon catalyst under the protection of inert gas at 70-80°C; after the reaction is completed, the reaction is filtered, the filter cake is dissolved with a solvent, and the catalyst is removed by filtering again, and the filtrate is added dropwise to deionized water to obtain the diamine monomer represented by formula (I).

6. The preparation method according to claim 5, characterized in that: The molar ratio of p-hydroxybenzaldehyde, p-nitroacetophenone and ammonium acetate is 1:(2-2.5):(12-14).

7. A method for preparing the polyimide according to claim 1, characterized in that: The following steps are involved: In a nitrogen atmosphere, in the presence of an alkaline substance, the polyimide represented by formula (II) reacts with fluorine-containing benzoyl chloride to obtain the polyimide represented by formula (III).

8. A polyimide film, characterized in that: The polyimide in the film is the polyimide represented by formula (II) and / or the polyimide represented by formula (III) according to claim 1.

9. A method for preparing a polyimide film according to claim 8, characterized in that: The polyimide represented by formula (II) and / or the polyimide represented by formula (III) is dissolved in a solvent, filtered through a filter membrane and then spin-coated onto a glass plate; the spin-coated glass is dried to remove the solvent in the coating so that the polyimide is solidified into a film; the dried glass plate is then placed in deionized water to peel off the polyimide film from the glass plate, thereby obtaining a polyimide film.

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