Benzocyclobutene-terminated diester diimide monomer, and preparation method therefor and curing method therefor

Abstract

The present invention relates to a preparation method and curing method for a benzocyclobutene-terminated diester diimide monomer. The chemical structural general formula of the benzocyclobutene-terminated diester diimide monomer is shown as formula (I), wherein R is: formula (II). The monomer can be dissolved in a low-boiling-point solvent, i.e., dichloromethane, has excellent processability, and can be directly heated, melted, cured and formed, or prepared into a polyimide film by means of a tape casting method. The polyimide material obtained after curing has excellent thermal stability, high transparency, and excellent dielectric properties.

Description

A benzocyclobutene-terminated diester-bisimide monomer and its preparation and curing method Technical Field

[0001] The invention relates to a preparation and curing method of a benzocyclobutene-terminated diester-bisimide monomer, and belongs to the field of polymer materials. Background Art

[0002] Polyimides are a class of polymers containing imide rings in their backbone. The rigid imide structure imparts unique properties to polyimides, resulting in excellent heat resistance and superior mechanical, electrical, radiation, and solvent resistance. Polyimides can be prepared by either condensation or addition methods. Condensation polyimides can be prepared using either a one-step chlorobenzene / m-cresol solvent method or a two-step method: polyamic acid is first generated in N,N-dimethylacetamide / N-methylpyrrolidone / N,N-dimethylformamide solvent, followed by thermal imidization (approximately 300°C) or chemical imidization using acetic anhydride / acetyl chloride / thionyl chloride reagents. In these methods, moisture release during thermal or chemical imidization can cause significant film shrinkage. Addition-type polyimides are environmentally friendly, do not generate small molecules, and facilitate thermosetting molding.

[0003] Benzocyclobutene groups possess excellent processing properties. They undergo thermal ring opening above 200°C, undergoing a [4+4] addition reaction with themselves to form an eight-membered ring, which can then form dimers or polymers. The reaction requires no catalyst and produces no small molecules, resulting in a pure product with minimal shrinkage. Therefore, benzocyclobutene groups can be used to prepare addition-type polyimide materials. The invention of a benzocyclobutene-terminated diester-bisimide monomer, its preparation, and its curing methods is highly beneficial.

[0004] Summary of the Invention

[0005] The present invention provides a benzocyclobutene-terminated diester-bisimide monomer, a method for preparing and curing the monomer. The monomer is soluble in the low-boiling-point solvent methylene chloride, exhibits excellent processing properties, and can be directly melt-cured and formed into a polyimide film by heating or casting. The curing process requires only heating and does not release small molecules. The resulting polyimide material exhibits excellent thermal stability, high transparency, and superior dielectric properties.

[0006] A benzocyclobutene-terminated diester-bisimide monomer has the following general chemical structure:

[0007] Where R is:

[0008] Preferably R is:

[0009] The preparation method of the present invention comprises the following steps:

[0010] (1) Adding 4-aminobenzocyclobutene and trimellitic anhydride to an organic solvent to react to prepare an imide of benzocyclobutene containing a carboxyl group, the structural formula of which is:

[0011] (2) adding the carboxyl-containing benzocyclobutene imide prepared in step (1), thionyl chloride, and an acid absorbent to an organic solvent for reaction to prepare an acid chloride-containing benzocyclobutene imide having the structural formula:

[0012] (3) adding the benzocyclobutene imide containing acid chloride prepared in step (2), a phenolic compound and an acid absorbent into an organic solvent, reacting the mixture, and separating the reaction product to obtain a benzocyclobutene-terminated diester-bisimide monomer having the following general structural formula:

[0013] Where R is:

[0014] The preferred preparation method of the present invention is: the organic solvent is glacial acetic acid, toluene or tetrahydrofuran. The acid absorbent is pyridine or triethylamine. The molar ratio of the reaction in step (1) is: 4-aminobenzocyclobutene: trimellitic anhydride: solvent = 1:1:40-50, and the reaction is carried out at 120°C for 20-28 hours. The molar ratio of the reaction in step (2) is: (1) prepared imide: dichloride: acid absorbent: solvent = 1:3:1:40-50, and the reaction is carried out at 60°C for 4-6 hours. The molar ratio of the reaction in step (3) is: (2) prepared acid chloride: phenolic compound: acid absorbent: solvent = 2:1:2:50-100, and the reaction is carried out at 60°C for 20-28 hours, wherein the structure of the phenolic compound used is preferably as follows:

[0015] After the reaction in step (3) is completed, 3-4 times the volume of anhydrous methanol is added to the reactant to precipitate a white solid, which is filtered to obtain the product.

[0016] The present invention also provides a curing method for a benzocyclobutene-terminated diester-bisimide monomer, which is characterized in that it is directly heated and melted for curing or dissolved in a solvent and then spin-coated on a substrate for curing, and cross-linked and cured at 250°C-280°C to form a polyimide material.

[0017] The monomer prepared by the present invention is soluble in the low-boiling-point solvent dichloromethane, has excellent processing properties, and can be directly heated, melt-cured, and formed or prepared into a polyimide film by a casting method. The preparation method of the present invention is simple, easy to control, has a high reaction conversion rate, and is relatively simple to purify after the reaction; the prepared imide can be directly formed into a polyimide material by thermal ring-opening addition polymerization, which is environmentally friendly and does not produce small molecules. The polyimide material prepared by the present invention has the characteristics of excellent thermal stability, high transparency, excellent dielectric properties, etc., and can be used as a thermosetting polymer material in 5G communications, microelectronics, packaging materials and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG1 is a hydrogen nuclear magnetic spectrum of a benzocyclobutene-terminated diester-bisimide monomer prepared by the method of the present invention.

[0019] FIG2 is a DSC spectrum of the benzocyclobutene-terminated diester-bisimide monomer prepared by the method of the present invention.

[0020] FIG3 is a TGA spectrum of the benzocyclobutene-terminated diester-bisimide monomer prepared by the method of the present invention. DETAILED DESCRIPTION

[0021] A method for preparing a benzocyclobutene-terminated diester-bisimide monomer comprises the following steps:

[0022] (1) Add 4-aminobenzocyclobutene and trimellitic anhydride to an anhydrous reagent in a molar ratio of 4-aminobenzocyclobutene: trimellitic anhydride: reagent = 1:1:40-50, and react at 120°C for 20-28 hours to prepare a carboxyl-containing benzocyclobutene imide having the structural formula:

[0023] (2) Add the imide prepared in step (1), thionyl chloride, and pyridine to the anhydrous reagent in a molar ratio of: imide prepared in step (1): thionyl chloride: pyridine: reagent = 1:3:1:40-50, and react at 60° C. for 4-6 hours. The structural formula of the prepared benzocyclobutene imide containing acyl chloride is:

[0024] (3) Add the acyl chloride prepared in step (2), various phenolic compounds and pyridine to an anhydrous reagent in a molar ratio of acyl chloride prepared in step (2): phenolic compound: pyridine: reagent = 2:1:2:50-100, and react at 60°C for 20-28h. The structure of the phenolic compound used is as follows:

[0025] (4) Add 3-4 times the volume of anhydrous methanol to the reactant in step (3) above, precipitate a white solid, and filter to obtain the product. It has the following chemical formula:

[0026] Where R is:

[0027] Specific examples of the benzocyclobutene-terminated diester-bisimide monomers of the present invention are listed below:

[0028] The structures of the four embodiments are listed below:

[0029] (Compound BBIA-BPA bis(2,3-dihydro-1,3-dioxo-2-(bicyclo[4.2.0]octa-1,3,5-trien-3-yl)-1H-isoindole-5-carboxylic acid) bisphenol A ester)

[0030] (Compound BBIA-BPS bis(2,3-dihydro-1,3-dioxo-2-(bicyclo[4.2.0]octa-1,3,5-trien-3-yl)-1H-isoindole-5-carboxylic acid) bisphenol S ester)

[0031] (Compound BBIA-BPAF bis(2,3-dihydro-1,3-dioxo-2-(bicyclo[4.2.0]octa-1,3,5-trien-3-yl)-1H-isoindole-5-carboxylic acid) bisphenol AF ester)

[0032] (Compound BBIA-DBA bis(2,3-dihydro-1,3-dioxo-2-(bicyclo[4.2.0]octa-1,3,5-trien-3-yl)-1H-isoindole-5-carboxylic acid) 2,2'-diallylbisphenol A ester)

[0033] [Example 1] Synthesis of Benzocyclobutene-Terminated Diester Bisimide Monomer of the Present Invention 1

[0034] Compound BBIA-BPA bis(2,3-dihydro-1,3-dioxo-2-(bicyclo[4.2.0]octa-1,3,5-trien-3-yl)-1H-isoindole-5-carboxylic acid) bisphenol A ester

[0035] 1.904 g (16.0 mmol) of 4-aminobenzocyclobutene and 3.070 g (16.0 mmol) of trimellitic anhydride were placed in a 200 mL round-bottom flask. Under a nitrogen atmosphere, 40 mL of glacial acetic acid was added. Stir and reflux at 120 ° C for 24 hours, cool to room temperature, add 120 mL of deionized water, a yellow solid precipitates, filter under reduced pressure, and wash three times with deionized water to obtain the imide of benzocyclobutene containing a carboxyl group. As shown in Figure 1, the nuclear magnetic hydrogen spectrum analysis of the present invention is as follows:

[0036] 1 H NMR (400MHz, DMSO): 13.75 (s, 1H), 8.41 (d, J = 7.7Hz, 1H), 8.30 (s, 1H), 8.07 (d, J = 7.7Hz, 1H), 7.23 (s, 2H), 7.15 (s, 1H), 3.20 (s, 4H).

[0037] Place 1.173 g (4.00 mmol) of the above product, 20 mL of toluene, and two drops of N,N-dimethylformamide in a 200 mL round-bottom flask. Under nitrogen, add 1.0 mL (1.64 g, 13.8 mmol) of thionyl chloride in an ice-water bath. After 10 minutes, add 0.5 mL (0.49 g, 6.2 mmol) of pyridine, and stir at reflux for 4 hours at 60°C. Cool to room temperature, and remove the solvent by rotary evaporation to obtain the benzocyclobutene imide containing the acid chloride.

[0038] To the round-bottom flask containing the acid chloride was added 0.457 g (2.00 mmol) of bisphenol A. Under a nitrogen atmosphere, 20 mL of anhydrous tetrahydrofuran and 0.5 mL (0.49 g, 6.2 mmol) of pyridine were added sequentially, and the mixture was stirred and refluxed at 65°C for 24 hours. After cooling to room temperature, 60 mL of anhydrous methanol was added and stirred for 0.5 hour. A large amount of white solid precipitated, which was filtered under reduced pressure and washed three times with anhydrous methanol to yield 1.146 g of compound BBIA-BPA, a 73.5% yield, as a white solid. The DSC spectrum of Example 1 in Figure 2 demonstrates that the present invention solidifies after melting. The TGA spectrum of Example 1 in Figure 3 demonstrates excellent thermal stability after molding.

[0039] 1 H NMR (400MHz, CDCl3): 8.76 (s, 2H), 8.63 (d, J = 7.7Hz, 2H), 8.19-8.02 (m, 2H), 7.35 (d, J = 8.2Hz, 4H), 7.24-7.05 (m, 10H), 3.24 (s, 8H), 1.75 (s, 6H).

[0040] The reaction flow chart is as follows:

[0041] [Example 2] Synthesis of Benzocyclobutene-Terminated Diester Bisimide Monomer of the Present Invention 2

[0042] Compound BBIA-BPS

[0043] The synthesis of the carboxyl-containing benzocyclobutene imide is the same as in Example 1.

[0044] The synthesis of acyl chloride is the same as in [Example 1].

[0045] To the round-bottom flask containing the acid chloride was added 0.501 g (2.00 mmol) of bisphenol S. Under a nitrogen atmosphere, 20 mL of anhydrous tetrahydrofuran and 0.5 mL (0.49 g, 6.2 mmol) of pyridine were added sequentially, and the mixture was stirred and refluxed at 65°C for 24 hours. After cooling to room temperature, 60 mL of anhydrous methanol was added and stirred for 0.5 hour. A large amount of white solid precipitated, which was filtered under reduced pressure and washed three times with anhydrous methanol to obtain 1.396 g of compound BBIA-BPS as a white solid, with a yield of 87.1%.

[0046] 1 H NMR (400MHz, CDCl3): 8.74 (s, 2H), 8.62 (d, J = 7.6Hz, 2H), 8.19-7.94 (m, 6H), 7.48 (d, J = 8.3Hz, 4H), 7.21 (s, 4H), 7.09 (s, 2H), 3.24 (s, 8H).

[0047] Reaction flow chart:

[0048] [Example 3] Synthesis of Benzocyclobutene-Terminated Diester Bisimide Monomer of the Present Invention 3

[0049] Compound BBIA-BPAF

[0050] The synthesis of the carboxyl-containing benzocyclobutene imide is the same as in Example 1.

[0051] The synthesis of acyl chloride is the same as in [Example 1].

[0052] To the round-bottom flask containing the acid chloride was added 0.672 g (2.00 mmol) of bisphenol AF. Under nitrogen, 20 mL of anhydrous tetrahydrofuran and 0.5 mL (0.49 g, 6.2 mmol) of pyridine were added sequentially, and the mixture was stirred and refluxed at 65°C for 24 hours. After cooling to room temperature, 60 mL of anhydrous methanol was added and stirred for 0.5 hour. A large amount of white solid precipitated, which was filtered under reduced pressure and washed three times with anhydrous methanol to obtain 1.513 g of compound BBIA-BPAF as a white solid, with a yield of 85.3%.

[0053] 1 H NMR (400MHz, CDCl3): 8.77 (s, 2H), 8.64 (d, J = 7.8Hz, 2H), 8.12 (d, J = 7.6Hz, 2H), 7. 55(d,J=8.5Hz,4H),7.34(d,J=8.4Hz,4H),7.21(s,4H),7.10(s,2H),3.25(s,8H). 19F NMR (376MHz,CDCl3):-63.79.

[0054] Reaction flow chart:

[0055] [Example 4] Synthesis of Benzocyclobutene-Terminated Diester Bisimide Monomer of the Present Invention

[0056] Compound BBIA-DBA

[0057] The synthesis of the carboxyl-containing benzocyclobutene imide is the same as in Example 1.

[0058] The synthesis of acyl chloride is the same as in [Example 1].

[0059] To the round-bottom flask containing the acid chloride was added 0.684 g (2.22 mmol) of DBA. Under nitrogen, 20 mL of anhydrous tetrahydrofuran and 0.5 mL (0.49 g, 6.2 mmol) of pyridine were added sequentially, and the mixture was stirred and refluxed at 65°C for 24 hours. After cooling to room temperature, 60 mL of anhydrous methanol was added and stirred for 0.5 hour. A large amount of white solid precipitated, which was filtered under reduced pressure and washed three times with anhydrous methanol to obtain 0.800 g of compound BBIA-DBA as a white solid in a 46.3% yield.

[0060] 1 H NMR(400MHz, CDCl3):8.74(s,2H),8.61(d,J=7.8Hz,2H),8.10(d,J=7.8Hz,2H),7.24-6.93(m,12H) ,5.88(td,J=16.5,6.4Hz,2H),5.16-4.71(m,4H),3.35(d,J=6.5Hz,4H),3.24(s,8H),1.73(s,6H).

[0061] Reaction flow chart:

[0062] [Example 5] Curing of BBIA-BPA prepared in [Example 1] of the present invention

[0063] A certain amount of benzocyclobutene-terminated diester-bisimide monomer BBIA-BPA powder was placed on a clean glass substrate and heated to 250°C to melt the powder into a pale yellow, low-viscosity liquid. The film was then cast and flattened while hot, then cured in an oven under a nitrogen atmosphere. The temperature was raised to 270°C for 1.5 hours and then 300°C for 0.5 hours, resulting in a smooth, pale yellow, transparent cured film. DSC curing behavior analysis revealed that BBIA-BPA had a melting point of 244°C and cross-linked at 272°C. Thermogravimetric analysis revealed an initial decomposition temperature (5% weight loss) of 445°C, and a carbon residue of 37% at 800°C.

[0064] Curing flow chart:

Claims

1. A benzocyclobutene-terminated diester-bisimide monomer, the general chemical structure of which is as follows: Where R is:

2. A benzocyclobutene-terminated diester-bisimide monomer according to claim 1, wherein R is:

3. A method for preparing a benzocyclobutene-terminated diester bisimide monomer, comprising the following steps: (1) Adding 4-aminobenzocyclobutene and trimellitic anhydride into an organic solvent to react, to prepare an imide of benzocyclobutene containing a carboxyl group, the structural formula of which is: (2) adding the carboxyl-containing benzocyclobutene imide prepared in step (1), thionyl chloride, and an acid absorbent into an organic solvent to react and prepare an acid chloride-containing benzocyclobutene imide having the structural formula: (3) adding the benzocyclobutene imide containing acid chloride prepared in step (2), a phenolic compound and an acid absorbent into an organic solvent for reaction, and separating the reaction product to obtain a benzocyclobutene-terminated diester bisimide monomer, the general structural formula of which is as follows: Where R is:

4. The method for preparing a benzocyclobutene-terminated diester-bisimide monomer according to claim 3, wherein the organic solvent is glacial acetic acid, toluene or tetrahydrofuran.

5. The method for preparing a benzocyclobutene-terminated diester-bisimide monomer according to claim 3, wherein the acid absorbent is pyridine or triethylamine.

6. The method for preparing a benzocyclobutene-terminated diester-bisimide monomer according to claim 3, wherein the molar ratio of the reaction in step (1) is: 4-aminobenzocyclobutene: trimellitic anhydride: solvent = 1:1:40-50, and the reaction is carried out at 120°C for 20-28h.

7. The method for preparing a benzocyclobutene-terminated diester-bisimide monomer according to claim 3, wherein the molar ratio of the reaction in step (2) is: (1) prepared imide: dichlorothionyl: acid absorbent: solvent = 1:3:1:40-50, and the reaction is carried out at 60°C for 4-6 hours.

8. The method for preparing a benzocyclobutene-terminated diester-bisimide monomer according to claim 3, wherein the molar ratio of the reaction in step (3) is: acid chloride prepared in (2): phenolic compound: acid absorbent: solvent = 2:1:2:50-100, and the reaction is carried out at 60° C. for 20-28 hours, wherein the structure of the phenolic compound used is as follows:

9. The method for preparing a benzocyclobutene-terminated diester-bisimide monomer according to claim 3, wherein after the reaction in step (3) is completed, 3-4 times the volume of anhydrous methanol is added to the reactant to precipitate a white solid, which is then filtered to obtain the product.

10. A method for curing a benzocyclobutene-terminated diester-bisimide monomer, characterized in that: It is directly heated to melt and solidify, or dissolved in a solvent and then spin-coated on a substrate for solidification, and cross-linked and solidified at 250°C-280°C to form a polyimide material.

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