Diamine monomer, method for preparing diamine monomer, polyimide, and method for preparing polyimide

Abstract

The present invention provides a diamine monomer, which contains an ether bond and a tert-butyl group. The present invention also provides a method for preparing the diamine monomer. Furthermore, the present invention also provides a polyimide prepared from the diamine monomer, and a method for preparing the polyimide. Compared with the prior art, the polyimide prepared from the diamine monomer of the present application has a low dielectric constant and low dielectric loss at high frequencies, and has excellent solubility, thermal stability and low water absorption, which can meet the requirements of 5G communications and can be used in microelectronics, information communications, aerospace, and ultra-large-scale integrated circuits.

Description

Technical Field

[0001] The present invention relates to the technical field of organic thin films, and in particular to a diamine monomer, a method for preparing the diamine monomer, polyimide and a method for preparing the polyimide. Background Art

[0002] In recent years, with the rapid development of 5G communications, electronic information equipment such as mobile communication equipment tends to develop in the direction of "lightweight, thin, and integrated", and flexible copper clad laminates (FCCL) that are light, thin, and bendable have received more and more attention. In addition to the required high-density integration, which improves the performance of the equipment, the loss of transmission signals is also a very important indicator under high-frequency conditions. With the increase in transmission lines, the loss of transmission signals will also increase, resulting in signal distortion or extended signal transmission time, so it is very important to reduce the loss of transmission signals. In order to cope with the development of high frequencies, the use of liquid crystal polymers (LCP) with low dielectric loss as the dielectric layer to prepare FCCL has a good effect, but its dielectric constant, heat resistance, and adhesion to copper foil still have room for improvement.

[0003] In order to solve the above problems, the use of modified polyimide as a dielectric layer is considered a solution. Polyimide is one of the best polymer materials in industrial engineering plastics. It has high mechanical strength, excellent thermal stability and dielectric properties, as well as good processing performance. Polyimide has been used in many fields, such as aerospace, microelectronics, medical and military industries. However, the dielectric constant (above 3.2) and dielectric loss (above 0.01) of traditional polyimide cannot meet the requirements of 5G communications. Summary of the invention

[0004] Based on this, the object of the present invention is to provide a diamine monomer, a method for preparing the diamine monomer, a polyimide and a method for preparing the polyimide, and the obtained polyimide material has good thermal properties and dielectric properties.

[0005] In one aspect, the present invention provides a diamine monomer, wherein the diamine monomer has the general structural formula:

[0006] H2N-Ar-NH2

[0007] Among them, the general structural formula of Ar is:

[0008]

[0009] In the formula, R1, R2 and R3 are selected from any one of the following structures:

[0010]

[0011] At most two of the R1, R2 and R3 are H groups.

[0012] In one embodiment, only one of R1, R2 and R3 is H group.

[0013] In a second aspect, the present invention provides a method for preparing the aforementioned diamine monomer, comprising the following steps:

[0014] (1) reacting a tert-butyl-containing resorcinol monomer with p-fluoronitrobenzene, m-fluoronitrobenzene or o-fluoronitrobenzene in an aprotic solvent and an alkaline environment to obtain a tert-butyl-containing dinitro compound;

[0015] (2) The dinitro compound is subjected to a reduction reaction by palladium carbon and hydrazine hydrate to obtain the diamine monomer.

[0016] In a third aspect, the present invention provides a method for preparing the aforementioned diamine monomer, comprising the following steps:

[0017] (1) reacting a bromine-containing resorcinol monomer with p-fluoronitrobenzene, m-fluoronitrobenzene or o-fluoronitrobenzene in an aprotic solvent and an alkaline environment to obtain a bromine-containing dinitro compound;

[0018] (2) subjecting the bromine-containing dinitro compound to a Suzuki reaction with phenylboric acid or phenylboric acid ester containing R1, R2 and R3 to obtain a dinitro compound containing the structures of R1, R2 and R3;

[0019] (3) The dinitro compound containing the structures of R1, R2 and R3 is subjected to a reduction reaction by palladium carbon and hydrazine hydrate to obtain the diamine monomer.

[0020] In a fourth aspect, the present invention provides use of the aforementioned diamine monomer in the preparation of polyimide, polyamideimide or polyamide.

[0021] In a fifth aspect, the present invention provides a polyimide, wherein the general structural formula of the polyimide is:

[0022]

[0023] In the formula, n and m represent the degree of polymerization, n is an integer of 10 to 10,000, m is an integer of 0 to 10,000, Ar is the aromatic unit fragment in the diamine monomer according to claim 1, X is a tetravalent aromatic hydrocarbon group, and Ar1 is the residue of the diamine.

[0024] In one embodiment, X is preferably any one of the following:

[0025]

[0026] In one embodiment, Ar1 is preferably any one of the following:

[0027]

[0028] In a sixth aspect, the present invention provides a method for preparing the aforementioned polyimide, wherein the diamine monomer and the dianhydride described in claim 1 are dissolved in a polar aprotic solvent at a molar ratio of 1:(1 to 1.2) in a nitrogen or argon atmosphere, and the reaction is continuously stirred for 24 to 48 hours at -10°C to 40°C to obtain a polyamic acid viscous liquid, and the polyimide can be obtained by chemical imidization or thermal imidization.

[0029] In a seventh aspect, the polyimide provided by the present invention is used in preparing a dielectric layer or an insulating layer of a flexible copper clad laminate.

[0030] Compared with the prior art, the diamine monomer of the present application is used to prepare polyimide, which has a low dielectric constant and low dielectric loss at high frequencies, and has excellent solubility, thermal stability and low water absorption. It can meet the requirements of 5G communications and can be used in microelectronics, information communications, aerospace, and ultra-large-scale integrated circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the hydrogen NMR spectrum of the diamine monomer prepared in Example 5 of the present invention;

[0032] Figure 2 This is the infrared spectrum of the polyimide prepared in Example 5 of the present invention;

[0033] Figure 3 This is the thermal gravimetric diagram of the polyimide prepared in Example 5 of the present invention. DETAILED DESCRIPTION

[0034] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0035] In view of the requirements of 5G communication in the prior art for the performance of polyimide films, this application introduces a new type of diamine monomer. By introducing tert-butyl and meta-ether bonds, the obtained polyimide has a low dielectric constant and low dielectric loss at high frequencies, which can meet the requirements of 5G communications and can be used in microelectronics, information communications, aerospace, and ultra-large-scale integrated circuits.

[0036] Polyphenylene oxide (PPO) has the characteristics of low polarity, high rigidity and low water absorption, so that it has the advantages of low dielectric constant, low dielectric loss, good mechanical properties and low expansion coefficient, and is an excellent dielectric constant for preparing high-frequency substrates. Based on this, the applicant introduces polyphenylene oxide into the polyimide structure to obtain a polyimide material with low dielectric characteristics. It is found in the experiment that compared with the para- and ortho-ether bonds, the meta-ether bond is more conducive to the preparation of a polyimide material with low dielectric loss. At the same time, the application introduces a large volume of tert-butyl groups and benzene groups in the side groups of the polyimide main chain, and utilizes its β relaxation motion to help reduce the dielectric constant of the polymer. In addition, the tert-butyl group and the benzene group belong to hydrophobic groups, which are conducive to reducing the water absorption and dielectric loss of polyimide. In addition, the introduction of the benzene group can also accommodate more tert-butyl groups, thereby reducing the dielectric constant, dielectric loss and water absorption of the polymer.

[0037] Specifically, the embodiment of the present invention discloses a diamine monomer, the general molecular structure of which is:

[0038] H2N-Ar-NH2

[0039] The specific molecular structure formula of Ar is:

[0040]

[0041] In the formula, R1, R2 and R3 are selected from any one of the following structures:

[0042]

[0043] At most two of R1, R2 and R3 are H groups.

[0044] Preferably, only one of R1, R2 and R3 is a H group.

[0045] The present application also provides a method for preparing a diamine monomer, comprising the following steps:

[0046] (1) reacting a tert-butyl-containing resorcinol monomer with p-fluoronitrobenzene, m-fluoronitrobenzene or o-fluoronitrobenzene in an aprotic solvent and an alkaline environment to obtain a tert-butyl-containing dinitro compound;

[0047] (2) The dinitro compound prepared in step (1) is subjected to a reduction reaction with palladium carbon and hydrazine hydrate to obtain a tert-butyl-containing diamine monomer.

[0048] Preferably, in step (1), the aprotic solvent is N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 1,4-dioxane, acetone, acetonitrile, toluene, chloroform, hexamethylphosphoric triamide or tetrahydrofuran.

[0049] Preferably, in step (1), when m-fluoronitrobenzene is used for the reaction, the aprotic solvent is anhydrous dimethyl sulfoxide; when p-fluoronitrobenzene or o-fluoronitrobenzene is used for the reaction, the aprotic solvent is anhydrous N,N-dimethylacetamide.

[0050] Preferably, in step (1), the alkaline environment is a potassium carbonate or sodium carbonate environment.

[0051] Preferably, in step (2), the solvent is ethanol and the palladium on carbon is 10% palladium on carbon.

[0052] In one embodiment, the present application also provides a method for preparing a diamine monomer, comprising the following steps:

[0053] (1) reacting a bromine-containing resorcinol monomer with p-fluoronitrobenzene, m-fluoronitrobenzene or o-fluoronitrobenzene in an aprotic solvent and an alkaline environment to obtain a bromine-containing dinitro compound;

[0054] (2) a bromine-containing dinitro compound and phenylboronic acid or phenylboronic acid ester containing R1, R2 and R3 are reacted by Suzuki reaction to obtain a dinitro compound containing R1, R2 and R3 structures;

[0055] (3) The dinitro compound containing the structures R1, R2 and R3 prepared in step (2) is subjected to a reduction reaction by palladium carbon and hydrazine hydrate to obtain a tert-butyl-containing diamine monomer.

[0056] Preferably, in step (1), the aprotic solvent is N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 1,4-dioxane, acetone, acetonitrile, toluene, chloroform, hexamethylphosphoric triamide or tetrahydrofuran.

[0057] Preferably, in step (1), when m-fluoronitrobenzene is used for the reaction, the aprotic solvent is anhydrous dimethyl sulfoxide; when p-fluoronitrobenzene or o-fluoronitrobenzene is used for the reaction, the aprotic solvent is anhydrous N,N-dimethylacetamide.

[0058] Preferably, in step (1), the alkaline environment is a potassium carbonate or sodium carbonate environment.

[0059] Preferably, in step (2), tetrahydrofuran is used as the solvent and an aqueous solution of potassium carbonate or sodium carbonate is used as the alkaline environment.

[0060] Preferably, in step (3), the solvent is ethanol and the palladium on carbon is 10% palladium on carbon.

[0061] Furthermore, the present application also provides a polyimide, the general molecular structure of which is:

[0062]

[0063] In the formula, n and m represent the degree of polymerization, n is an integer of 10 to 10,000, m is an integer of 0 to 10,000, Ar is the aromatic unit fragment in the diamine monomer according to claim 1, X is a tetravalent aromatic hydrocarbon group, and Ar1 is the residue of the diamine.

[0064] Among them, the X structure is preferably any of the following:

[0065]

[0066] Ar1 is preferably any of the following:

[0067]

[0068] The present application also provides a method for preparing polyimide, comprising the following steps:

[0069] In a nitrogen or argon atmosphere, the aforementioned diamine monomer and dianhydride are dissolved in a polar aprotic solvent at a molar ratio of 1:(1-1.2), and the reaction is continuously stirred at -10°C to 40°C for 24 to 48 hours to obtain a polyamic acid viscous liquid, which can be obtained by chemical imidization or thermal imidization to obtain the polyimide of the aforementioned general formula.

[0070] Preferably, in a nitrogen or argon atmosphere, a diamine monomer containing a tert-butyl structure and a dianhydride are dissolved in an aprotic solvent at a molar ratio of 1:1.02; the optimal reaction temperature is -10°C.

[0071] Preferably, the aprotic solvent is selected from one or more mixed solvents of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, cyclopentane, 1,4-dioxane, acetone, acetonitrile, toluene, chloroform, hexamethylphosphoramide and tetrahydrofuran.

[0072] Preferably, the specific steps of the thermal imidization are: applying a certain thickness of viscous polyamic acid glue on a glass plate, placing the glass plate in an oven, and heating the room temperature to 80°C for 20 minutes, heating from 80°C to 180°C for 1 hour, heating to 230°C for 30 minutes, and then heating to 300°C for 60 minutes, maintaining at 300°C for 30 minutes, and obtaining a polyimide film after cooling.

[0073] Preferably, the specific steps of the chemical imidization are: adding a dehydrating agent and a catalyst to a polyamic acid viscous liquid, wherein acetic anhydride is used as the dehydrating agent and pyridine is used as the catalyst, stirring at room temperature for 24 to 40 hours, then pouring into a large amount of distilled water to obtain a fibrous polyimide, extracting with ethanol, and drying for use; dissolving the dried polyimide fiber in a solvent with a certain solid content, and baking the film according to the heating program of thermal imidization.

[0074] In order to further understand the present invention, the preparation method of the diamine monomer and the preparation method of the polyimide polymer provided by the present invention are described in detail below in conjunction with the embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0075] Example 1

[0076] 4,6-di-tert-butylresorcinol (5 g, 22.5 mmol), p-fluoronitrobenzene (10.575 g, 15 mmol), potassium carbonate (4.036 g, 29.25 mmol) and 70 ml of anhydrous N,N-dimethylacetamide were reacted under nitrogen protection. After the reaction, the solid was collected by filtration and recrystallized to obtain a dinitro compound. The dinitro compound was characterized by nuclear magnetic resonance, and the result was: 1 H NMR (DMSO-d6, 400MHz): =8.24(m,4H),7.54(s,1H),7.15(m,4H),6.71(s,1H),1.36(s,18H).

[0077] The above dinitro compound (2.86 g, 6.2 mmol), 0.52 g palladium carbon and 80 ml of anhydrous ethanol were added to a 250 ml three-necked flask, and 15 ml of hydrazine hydrate was slowly added dropwise to the reaction solution. After the reaction was continued for 12 hours, the target product diamine A was obtained by filtration and recrystallization. Diamine A was characterized by nuclear magnetic resonance, and the result was: 1 H NMR (DMSO-d6, 400MHz): 7.26 (s, 1H), 6.58 (m, 4H), 6.48 (m, 4H), 6.09 (s, 1H), 1.36 (s, 18H).

[0078]

[0079] Under the protection of nitrogen, diamine A (1mmol, 0.404g), anhydrous N,N-dimethylacetamide (5.6ml), 4,4'-(4,4'-isopropyldiphenyloxy) diphthalic anhydride (1mmol, 0.5208g) were added to the reaction bottle. After continuous stirring at low temperature for 24h, a homogeneous and transparent polyamide acid glue solution was obtained. After removing bubbles, it was poured onto a clean glass plate and scraped. After that, it was placed in an oven and subjected to programmed temperature rise to complete amidation. After that, it was cooled to room temperature and immersed in hot water for demolding. The film thickness meter measured that the polyimide film (PI-1) with a thickness of about 30μm was obtained. The structure is as follows:

[0080]

[0081] Example 2

[0082] 4,6-di-tert-butylresorcinol (5 g, 22.5 mmol), m-fluoronitrobenzene (10.575 g, 150 mmol), potassium carbonate (4.485 g, 32.5 mmol) and 70 ml of anhydrous dimethyl sulfoxide were reacted under nitrogen protection. After the reaction, the solid was collected by filtration and recrystallized to obtain a dinitro compound. The dinitro compound was characterized by nuclear magnetic resonance, and the result was: 1 H NMR (DMSO-d6, 400MHz): =7.89 (dd, 2H), 7.60 (m, 5H), 7.41 (dd, 2H), 6.62 (s, 1H), 1.38 (s, 18H).

[0083] The above dinitro compound (1.91 g, 4.12 mmol), 0.85 g palladium carbon and 80 ml of anhydrous ethanol were added to a 250 ml three-necked flask, and 15 ml of hydrazine hydrate was slowly added dropwise to the reaction solution. After the reaction was continued for 12 hours, the target product diamine B was obtained by filtration and recrystallization. Diamine B was characterized by nuclear magnetic resonance, and the result was: 1 H NMR(DMSO-d6,400MHz): =7.34(d,1H),6.91(t,2H),6.30(d,1H),6.22(dd,2H),6.09(m,4H),5.15(s,4H),1.36(s,18H).

[0084]

[0085] Under the protection of nitrogen, diamine B (1mmol, 0.404g), anhydrous N,N-dimethylacetamide (2.96ml), 4,4'-(4,4'-isopropyldiphenyloxy) diphthalic anhydride (1mmol, 0.5208g) were added to the reaction bottle. After continuous stirring at low temperature for 24h, a homogeneous and transparent polyamide acid glue solution was obtained. After removing bubbles, it was poured onto a clean glass plate and scraped. After that, it was placed in an oven and subjected to programmed temperature rise to complete amidation. After that, it was cooled to room temperature, immersed in hot water to remove the film, and the film thickness was measured by a film thickness meter to obtain a polyimide film (PI-2) with a thickness of about 30μm. The structure is as follows:

[0086]

[0087] Example 3

[0088] 4,6-di-tert-butylresorcinol (5 g, 22.5 mmol), o-fluoronitrobenzene (10.575 g, 150 mmol), potassium carbonate (4.485 g, 32.5 mmol) and 70 ml of anhydrous N,N-dimethylacetamide were reacted under nitrogen protection. After the reaction, the solid was collected by filtration and recrystallized to obtain a dinitro compound. The dinitro compound was characterized by nuclear magnetic resonance, and the result was: 1 H NMR (DMSO-d6, 400MHz): =7.98(dd,2H),7.61(ddd,2H),7.50(s,1H),7.24(ddd,2H),7.05(dd,2H),6.53(s,1H),1.39(s,18H).

[0089] The above dinitro compound (2.8 g, 6.03 mmol), 0.75 g palladium carbon and 80 ml of anhydrous ethanol were added to a 250 ml three-necked flask, and 15 ml of hydrazine hydrate was slowly added dropwise to the reaction solution. After the reaction was continued for 12 hours, the mixture was filtered and allowed to stand and cool to obtain the target product diamine C. Diamine C was characterized by nuclear magnetic resonance, and the result was: 1 H NMR (DMSO-d6, 400MHz): = 7.34 (s, 1H), 6.75 (ddd, 2H), 6.70 (dd, 2H), 6.52 (dd, 2H), 6.42 (ddd, 2H), 6.05 (s, 1H), 4.74 (s, 4H), 1.40 (s, 18H).

[0090]

[0091] Under the protection of nitrogen, diamine C (1mmol, 0.404g), anhydrous N,N-dimethylacetamide (2.96ml), 4,4'-(4,4'-isopropyldiphenyloxy) diphthalic anhydride (1mmol, 0.5208g) were added to the reaction bottle. After continuous stirring at low temperature for 24h, a homogeneous and transparent polyamic acid glue solution was obtained. After adding 1ml pyridine and 1ml acetic anhydride for acylation, the obtained polyimide glue solution was poured into ethanol to obtain polyimide fiber. After extraction and drying, the obtained polyimide fiber was dissolved in N,N-dimethylacetamide. After removing bubbles, it was poured onto a clean glass plate and scraped. After that, it was placed in an oven to further amidate by program heating, cooled to room temperature, immersed in hot water for demolding, and measured by a film thickness meter to obtain a polyimide film (PI-3) with a thickness of about 30μm. The structure is as follows:

[0092]

[0093] Example 4

[0094] 5-Bromoresorcinol (5.5 g, 29 mmol), p-fluoronitrobenzene (12.69 g, 90 mmol), potassium carbonate (5.382 g, 39 mmol) and 90 ml of anhydrous N,N-dimethylacetamide were reacted under nitrogen protection. After the reaction, the solid was collected by filtration and recrystallized to obtain a bromine-containing dinitro compound. The dinitro compound was characterized by nuclear magnetic resonance, and the result was: 1 H NMR (DMSO-d6, 400MHz): =8.28(m,4H),7.37(d,2H),7.29(m,4H),7.12(t,1H).

[0095] The above-mentioned bromine-containing dinitro compound (10 mmol, 4.3 g), a small amount of tetratriylphosphine palladium and 200 ml of tetrahydrofuran were reacted at room temperature under the protection of nitrogen, and then 30 ml of 2 mol / L potassium carbonate solution and 4-tert-butylphenylboric acid (30 mmol, 5.34 g) were added, and reacted under the protection of nitrogen, and the liquid was separated after cooling, and the obtained crude product was recrystallized to obtain a tert-butyl-containing dinitro compound. The tert-butyl-containing dinitro compound was characterized by nuclear magnetic resonance, and the result was: 1 HNMR(DMSO-d6,400MHz): =8.28(m,4H),7.65(m,2H),7.47(m,2H),7.40(d,2H),7.29(m,4H),7.03(t,1H),1.30(s,9H).

[0096] The above-mentioned tert-butyl-containing dinitro compound (2.8 g, 5.8 mmol), 0.74 g palladium carbon and 80 ml of anhydrous ethanol were added into a 250 ml three-necked flask, and 11 ml of hydrazine hydrate was slowly added dropwise into the reaction solution. After the reaction was continued for 12 hours, the filtrate was filtered while hot, and the target product diamine D was separated by column chromatography. 1 H NMR (DMSO-d6, 400MHz): = 7.40 (q, 4H), 6.80 (m, 4H), 6.68 (d, 2H), 6.59 (m, 4H), 6.30 (t, 1H), 5.02 (s, 4H), 1.27 (s, 9H).

[0097]

[0098] Under the protection of nitrogen, diamine D (1mmol, 0.424g), anhydrous N,N-dimethylacetamide (4.03ml), 4,4'-(4,4'-isopropyldiphenyloxy) diphthalic anhydride (1mmol, 0.5208g) were added to the reaction bottle. After continuous stirring at low temperature for 24h, a homogeneous and transparent polyamide acid glue solution was obtained. After removing bubbles, it was poured onto a clean glass plate and scraped. After that, it was placed in an oven and subjected to programmed temperature rise to complete amidation. After that, it was cooled to room temperature, immersed in hot water to remove the film, and the film thickness was measured by a film thickness meter to obtain a polyimide film (PI-4) with a thickness of about 30μm. The structure is as follows:

[0099]

[0100] Example 5

[0101] 5-Bromoresorcinol (5.5 g, 29 mmol), p-fluoronitrobenzene (12.69 g, 90 mmol), potassium carbonate (5.382 g, 39 mmol) and 90 ml of anhydrous N,N-dimethylacetamide were reacted under nitrogen protection. After the reaction, the solid was collected by filtration and recrystallized to obtain a bromine-containing dinitro compound. The dinitro compound was characterized by nuclear magnetic resonance, and the result was: 1 H NMR (DMSO-d6, 400MHz): δ = 8.28 (m, 4H), 7.37 (d, 2H), 7.29 (m, 4H), 7.12 (t, 1H).

[0102] The above-mentioned bromine-containing dinitro compound (10mmol, 4.3g), a small amount of tetratriylphosphine palladium and 200ml of tetrahydrofuran were reacted at room temperature under the protection of nitrogen, and then 30ml of 2mol / L potassium carbonate solution and 3,5-di-tert-butylphenylboric acid (30mmol, 7.02g) were added, and reacted under the protection of nitrogen, cooled and separated, and then recrystallized to obtain a tert-butyl-containing dinitro compound. The tert-butyl-containing dinitro compound was characterized by nuclear magnetic resonance, and the result was: 1 H NMR (DMSO-d6, 400MHz): δ = 8.27 (m, 4H), 7.47 (m, 5H), 7.27 (m, 4H), 7.04 (t, 1H), 1.32 (s, 18H).

[0103] The above-mentioned tert-butyl-containing dinitro compound (2.8 g, 5.8 mmol), 0.74 g palladium carbon and 80 ml of anhydrous ethanol were added to a 250 ml three-necked flask, and 11 ml of hydrazine hydrate was slowly added dropwise to the reaction solution. After the reaction was continued for 12 hours, the filtrate was filtered while hot, cooled and filtered to obtain the target product diamine E. Diamine E was characterized by nuclear magnetic resonance, and the results were: 1H NMR (DMSO-d6, 400MHz): δ = 7.39 (t, 1H), 7.26 (d, 2H), 6.80 (m, 4H), 6.73 (d, 2H), 6.57 (m, 4H), 6.25 (t, 1H), 4.99 (s, 4H), 1.29 (s, 18H).

[0104]

[0105] Under the protection of nitrogen, diamine E (1mmol, 0.48g), anhydrous N,N-dimethylacetamide (7.84ml), 4,4'-(4,4'-isopropyldiphenyloxy) diphthalic anhydride (1mmol, 0.5208g) were added to the reaction bottle. After continuous stirring at low temperature for 24h, a homogeneous and transparent polyamide acid glue solution was obtained. After removing bubbles, it was poured onto a clean glass plate and scraped. After that, it was placed in an oven and subjected to programmed temperature rise to complete amidation. After that, it was cooled to room temperature and immersed in hot water to remove the film. The film thickness meter measured that the polyimide film (PI-5) with a thickness of about 30μm was obtained. The structure is as follows:

[0106]

[0107] Example 6

[0108] Under the protection of nitrogen, 1,3-bis(4-aminooxy)benzene (1mmol, 0.292g), diamine A (1mmol, 0.404g), anhydrous N,N-dimethylacetamide (8.5ml), 4,4'-(4,4'-isopropyldiphenyloxy) diphthalic anhydride (2mmol, 1.0416g) were added to the reaction bottle. After continuous stirring at low temperature for 24h, a homogeneous and transparent polyamic acid glue solution was obtained. After removing bubbles, it was poured onto a clean glass plate and scraped. After that, it was placed in an oven and fully amidated by programmed temperature rise. After cooling to room temperature, it was immersed in hot water for demolding. The film thickness meter measured that the polyimide film (PI-6) with a thickness of about 30μm was obtained. The structure is as follows (n / m=1 / 1):

[0109]

[0110] Comparative Example 1

[0111] Under the protection of nitrogen, 1,3-bis(4-aminooxy)benzene (1mmol, 0.292g), anhydrous N,N-dimethylacetamide (7.8ml), 4,4'-(4,4'-isopropyldiphenyloxy)diphthalic anhydride (1mmol, 0.5208g) were added to the reaction bottle. After continuous stirring at low temperature for 24h, a homogeneous and transparent polyamide acid glue solution was obtained. After removing bubbles, it was poured onto a clean glass plate and scraped. After that, it was placed in an oven and subjected to programmed temperature rise to complete amidation. After that, it was cooled to room temperature and immersed in hot water for demolding. The film thickness meter measured that a polyimide film (PI-7) with a thickness of about 30μm was obtained. The structure is as follows:

[0112]

[0113] The performance tests were performed on the polyimides prepared in Examples 1-6 and Comparative Example 1. The results are shown in Tables 1 and 2.

[0114] Table 1 Polyimide performance data table

[0115]

[0116] Table 2 Solubility data of polyimide

[0117] Polyimide Solvents NMP DMF m-Cresol DMSO DMAc THF TCM Comparative Example 1 ++ ++ ++ -- ++ ++ ++ Example 1 ++ ++ ++ +- ++ ++ ++ Example 2 ++ ++ ++ ++ ++ ++ ++ Example 3 ++ ++ ++ ++ ++ ++ ++ Example 4 ++ ++ ++ -- ++ ++ ++ Example 5 ++ ++ ++ -- ++ ++ ++ Example 6 ++ ++ ++ +- ++ ++ ++

[0118] Among them, ++ means soluble at room temperature, +- means partially soluble at room temperature, and - means insoluble at room temperature; NMP is N-methylpyrrolidone, DMF is N,N-dimethylformamide, m-Cresol is m-cresol, DMSO is dimethyl sulfoxide, DMAc is N,N-dimethylacetamide, THF is tetrahydrofuran, and TCM is chloroform.

[0119] As can be seen from Tables 1 and 2, compared with Comparative Example 1, the dielectric constant of the polyimide prepared by the present invention at 10 GHz is lower, and lower than the dielectric constant of the traditional polyimide (above 3.2); the dielectric loss is low, which is more advantageous than the dielectric loss of the traditional polyimide (above 0.01). In addition, the polyimide prepared by the present invention has excellent solubility, thermal stability and low water absorption, so that it can meet the requirements of 5G communication and can be used in the fields of microelectronics, information communication, aerospace and ultra-large-scale integrated circuits.

[0120] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A diamine monomer, characterized in that: The general structural formula of the diamine monomer is: H2N-Ar-NH2 Among them, the general structural formula of Ar is: In the formula, R1 and R3 are tert-butyl groups, and R2 is H; Alternatively, R1 and R3 are H, and R2 is selected from any one of the following structures:

2. A method for preparing the diamine monomer according to claim 1, comprising the following steps: (1) reacting a tert-butyl-containing resorcinol monomer with p-fluoronitrobenzene, m-fluoronitrobenzene or o-fluoronitrobenzene in an aprotic solvent and an alkaline environment to obtain a tert-butyl-containing dinitro compound; (2) The dinitro compound is subjected to a reduction reaction by palladium carbon and hydrazine hydrate to obtain the diamine monomer.

3. The method for preparing a diamine monomer according to claim 1, comprising the following steps: (1) reacting a bromine-containing resorcinol monomer with p-fluoronitrobenzene, m-fluoronitrobenzene or o-fluoronitrobenzene in an aprotic solvent and an alkaline environment to obtain a bromine-containing dinitro compound; (2) subjecting the bromine-containing dinitro compound to a Suzuki reaction with phenylboric acid or phenylboric acid ester containing R1, R2 and R3 to obtain a dinitro compound containing the structures of R1, R2 and R3; (3) The dinitro compound containing the structures of R1, R2 and R3 is subjected to a reduction reaction by palladium carbon and hydrazine hydrate to obtain the diamine monomer.

4. Use of the diamine monomer according to claim 1 in the preparation of polyimide, polyamideimide or polyamide.

5. A polyimide, characterized in that: The general structural formula of the polyimide is: In the formula, n and m represent the degree of polymerization, n is an integer of 10 to 10,000, m is an integer of 0 to 10,000, Ar is the aromatic unit fragment in the diamine monomer according to claim 1, Ar1 is the residue of the diamine, and X is selected from any one of the following:

6. The polyimide according to claim 5, characterized in that The Ar1 is preferably any one of the following:

7. A method for preparing a polyimide according to any one of claims 5 to 6, characterized in that: In a nitrogen or argon atmosphere, the diamine monomer and the dianhydride described in claim 1 are dissolved in a polar aprotic solvent at a molar ratio of 1: (1 to 1.2), and the reaction is continuously stirred at -10°C to 40°C for 24 to 48 hours to obtain a polyamic acid viscous liquid, and the polyimide can be obtained by chemical imidization or thermal imidization.

8. Use of the polyimide according to any one of claims 5 to 6 in preparing a dielectric layer or an insulating layer of a flexible copper clad laminate.

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