Preparation method and application of terminal-group-crosslinked high-temperature-resistant polyimide film
By introducing cross-linkable cyano groups into the polyimide end groups, high-temperature resistant polyimide films that can be processed in solution are prepared, which solves the problem of balancing heat resistance and solubility, realizes polyimide films with high heat resistance and good processability, and expands its application range.
Patent Information
- Application Number
- CN202410393859.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-02
- Publication Date
- 2025-10-14
AI Technical Summary
Existing polyimide materials have contradictions in terms of both heat resistance and solubility and processing performance. In particular, polyimide with a glass transition temperature exceeding 400°C has poor solubility, which makes molding and processing difficult, and the degree of main chain cross-linking is difficult to control.
By adopting the end group cross-linking method, cross-linkable cyano groups are introduced into the end groups of polyimide to prepare solution-processable polyimide materials. The main chain molecular weight and cross-linkable end group content can be adjusted to control the cross-linking density and aggregation structure. The glass transition temperature after cross-linking can reach above 400°C.
It achieves high heat resistance and good solution processability, with controllable cross-linking density and aggregation structure, and is suitable for aerospace, electronics, machinery, automobile and other fields.
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Abstract
Description
Technical Field
[0001] The technical field of the present invention is high-temperature resistant engineering plastics, and relates to a preparation method and application of a terminal-crosslinkable high-temperature resistant polyimide film. Background Art
[0002] Polyimides are polymer compounds containing repeating imide units in their molecular chains, derived from the polycondensation reaction of dianhydride and diamine monomers. Polyimides possess numerous excellent properties, including excellent insulation, mechanical properties, solvent resistance, and dielectric properties, and are widely used in flexible substrates, optical switches, solar panels, wires and cables, and other fields. With the rapid development of modern industries such as aerospace and rocket engines, higher demands have been placed on the heat resistance of polyimides. However, this heat resistance often struggles with solution processing performance. In particular, polyimides with glass transition temperatures exceeding 400°C typically have poor solubility, making the molding and processing of high-temperature resistant polyimide materials difficult. Therefore, developing polyimide materials that combine heat resistance with good solution processability has become an urgent research challenge. Recent studies have reported that researchers use monomers containing crosslinkable cyano groups to polymerize a main-chain crosslinked polyimide. This is then followed by post-heat crosslinking to produce a highly heat-resistant thermosetting polyimide. However, since each repeating unit on the main chain of this method contains a cross-linkable cyano group, it is difficult to control the degree of cross-linking and the aggregate structure of the product, which brings difficult-to-solve technical problems for subsequent molding processing. Summary of the Invention
[0003] To solve the above-mentioned problems, the present invention provides a method for preparing a high-temperature resistant polyimide that can be solution-processed and has a cross-linkable end-capping structure. The polyimide prepared by this method contains only cross-linkable cyano groups at the end groups, and the main chain molecular weight and the content of cross-linkable end groups are adjustable, making it easier to control the cross-linking density and aggregate structure of the polyimide during post-processing cross-linking molding. The polyimide material prepared by the present invention can be dissolved in a variety of commonly used organic solvents, and the glass transition temperature of the cross-linked product can reach above 400°C. It has high heat resistance, good solution processability and mechanical properties, and has good application prospects.
[0004] In order to achieve the above technical effects, the technical solution of the present invention is:
[0005] A method for preparing a high-temperature resistant polyimide film with end-group cross-linking comprises the following steps:
[0006] Step 1: Weighing a diamine monomer, a dianhydride monomer, an end-capping monomer, and a catalyst respectively and dissolving them in a solvent, wherein the molar ratio of the diamine monomer to the dianhydride monomer is 0.7:1-0.95:1, the molar ratio of the end-capping monomer to the dianhydride monomer is 0.6:1-0.1:1, the weight percentage of the catalyst to the total monomers is 2.5-7.5%, and the concentration of the solution is 0.1-0.5 g / ml. The mixture is reacted at 20-60° C. under an inert gas atmosphere for 0.5-4 hours, at 60-120° C. for 0.5-4 hours, and then at 120-200° C. for 0.5-48 hours to obtain a polyimide solution, cooling the reaction solution and precipitating it in a precipitant, washing, filtering, and drying to obtain a polyimide powder product;
[0007] Step 2: dissolving the polyimide prepared in step 1 or a mixture of polyimide and a curing catalyst in a solvent to obtain a polyimide solution, wherein the mass concentration of the polyimide in the solution is 1-10%; coating the obtained solution on a substrate, and maintaining the temperature in the range of 20-160° C. for 0.5-24 hours to obtain a polyimide film, wherein the coating method can be casting, spin coating, brush coating or doctor blade coating;
[0008] Step 3: heating the polyimide film obtained in step 2 to 200-300° C. and maintaining it for 1-4 hours, then to 300-380° C. and maintaining it for 1-4 hours, and then further heating it to 380-420° C. and maintaining it for 4-12 hours to obtain a polyimide film with a cross-linked structure.
[0009] The diamine monomer in step 1 may be one or a mixture of two or more of the following diamine compounds, but not limited to:
[0010]
[0011] The dianhydride monomer in step 1 may be one or a mixture of two or more of the following dianhydride compounds, but not limited to:
[0012]
[0013] The end-capping monomer in step 1 may be one or a mixture of two or more of the following monoamine compounds, but not limited to:
[0014]
[0015] The catalyst in step 1 may be one or a mixture of two or more of the following compounds, but not limited to:
[0016]
[0017] The solvent in step 1 is m-cresol and a mixture of m-cresol with one or more of halogenated hydrocarbons, nitrogen-methyl pyrrolidone, nitrogen, nitrogen-dimethylformamide, nitrogen, nitrogen-dimethylacetamide, and dimethyl sulfoxide in any proportion; the precipitant is a mixture of one or more of alkanes, ethanol, methanol, and water in any proportion.
[0018] The solvent in step 2 is one or a mixture of two or more of nitrogen-methylpyrrolidone, nitrogen-dimethylformamide, nitrogen-dimethylacetamide, and dimethyl sulfoxide.
[0019] The curing catalyst in step 2 is one or a mixture of two or more of ferric chloride, zinc chloride, cobalt acetylacetonate, ferric acetylacetonate, ethylenediamine, triethylamine, and aniline; the mass concentration of the curing catalyst in the system solution is 0-5%.
[0020] In step 2, the substrate is a glass plate, an aluminum plate, a stainless steel plate or a copper plate.
[0021] The present invention also seeks to protect the high-temperature resistant polyimide film with a cross-linked structure prepared by the above method, as well as the application of the high-temperature resistant polyimide film in the fields of aerospace, electronic appliances, machinery and automobiles.
[0022] Beneficial effects
[0023] The polyimide film prepared by the present invention has the characteristics of simple preparation process, excellent heat resistance, good solution processing performance, mechanical properties, dimensional stability, etc., overcomes the shortcomings of traditional main chain cross-linked polyimide, effectively improves the scope of use of polyimide film, and can be widely used in aerospace, electronic appliances, machinery and automobile fields. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 Thermogravimetric analysis curve of the polyimide PI-1 film prepared in the present invention, the test conditions are: nitrogen atmosphere, heating rate 10°C / min, test range 30-800°C;
[0025] Figure 2 The differential scanning calorimetry analysis curve of the polyimide PI-1 film prepared in the present invention is tested under the following conditions: nitrogen atmosphere, heating rate of 10°C / min, and test range of 30-400°C;
[0026] Figure 3 The dynamic thermomechanical analysis curve of the polyimide PI-1 film prepared in the present invention is tested under the following conditions: nitrogen atmosphere, heating rate 5°C / min, test frequency 1 Hz, and test range 30-400°C;
[0027] Figure 4The stress-strain curve of the polyimide PI-1 film prepared in the present invention is tested under the condition of 2 mm / min. DETAILED DESCRIPTION
[0028] The present invention selects monoamines containing a cyano structure, such as 4-aminobenzonitrile, as end-capping monomers, uses p-phenylenediamine, 4,4'-diaminodiphenyl ether, 1,4-cyclohexanediamine, etc. as diamine monomers, and uses 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride, etc. as dianhydride monomers to design and synthesize a series of cyano-terminated polyimides with adjustable molecular weight, and obtains a high-temperature resistant polyimide film through thermal crosslinking.
[0029] To more clearly illustrate the purpose, technical solutions, and advantages of the present disclosure, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the following description of the embodiments is intended to explain and illustrate the overall concept of the present invention and should not be construed as limiting the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.
[0030] Example 1
[0031] Preparation of high temperature resistant polyimide PI-1 film
[0032] Step 1: Weigh 0.4768 g of 4,4'-diaminodiphenyl ether, 1.4808 g of 4,4'-(hexafluoroisopropylene) diphthalic anhydride, 0.3 g of 4-aminophthalonitrile, 0.15 ml of isoquinoline, and 15 ml of m-cresol, stir and mix, react at room temperature for 2 hours, react at 60°C for 4 hours under a nitrogen atmosphere, heat to 120°C for 4 hours, heat to 180°C for 48 hours to obtain a polyimide solution, and then precipitate the polyimide in anhydrous ethanol, filter, and dry to obtain a polyimide powder;
[0033] Step 2: Prepare a 50 mg / ml solution of polyimide powder in nitrogen-dimethylacetamide, evenly coat the solution on the surface of a glass plate, and heat to 60°C for 4 hours and then to 120°C for 2 hours to obtain a polyimide film.
[0034] Step 3: heating the polyimide film to 300° C. for 2 hours, then heating it to 380° C. for 12 hours for cross-linking, and then cooling it to room temperature to obtain a highly heat-resistant polyimide film with a cross-linked structure.
[0035] The polyimide film has a 5% weight loss temperature of 526°C, a glass transition temperature of greater than 400°C, a tensile strength of 99 MPa, a tensile modulus of 2.9 GPa, and an elongation at break of 3.4% as measured by a dynamic mechanical analyzer.
[0036] Example 2
[0037] Preparation of high-temperature-resistant polyimide PI-2 film
[0038] Step one: 4,4'-diaminodiphenyl ether 0.8471 g, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride 2.2212 g, 4-aminophthalonitrile 0.24 g, isoquinoline 0.15 mL, m-cresol 15 mL were stirred and mixed, and reacted at room temperature for 2 hours under a nitrogen atmosphere, reacted at 60°C for 4 hours, reacted at 120°C for 4 hours, reacted at 180°C for 48 hours, to obtain a polyimide solution, then the polyimide was precipitated in anhydrous ethanol, suction filtered, and dried to obtain a polyimide powder;
[0039] Step two: the polyimide powder was dissolved in N,N-dimethylacetamide to obtain a solution with a concentration of 50 mg / mL, the solution was uniformly coated on the surface of a glass plate, heated to 60°C for 4 hours, and heated to 120°C for 2 hours, to obtain a polyimide film;
[0040] Step three: the polyimide film was heated to 300°C for 2 hours, and crosslinked at 380°C for 12 hours, and then cooled to room temperature to obtain a high-temperature-resistant polyimide film with a crosslinked structure.
[0041] The polyimide film has a 5% weight loss temperature of 527°C, a glass transition temperature of 366°C, a tensile strength of 136 MPa, a tensile modulus of 2.4 GPa, and an elongation at break of 5.6% as measured by a dynamic mechanical analyzer.
[0042] Example 3
[0043] Preparation of high-temperature-resistant polyimide PI-3 film
[0044] Step one: p-phenylenediamine 0.4731 g, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride 2.2212 g, 4-aminophthalonitrile 0.16 g, isoquinoline 0.15 mL, m-cresol 15 mL were stirred and mixed, and reacted at room temperature for 2 hours under a nitrogen atmosphere, reacted at 60°C for 4 hours, reacted at 100°C for 4 hours, and reacted at 150°C for 24 hours, to obtain a polyimide solution, then the polyimide was precipitated in anhydrous ethanol, suction filtered, and dried to obtain a polyimide powder;
[0045] Step two: the polyimide powder was dissolved in N,N-dimethylacetamide to form a solution with a concentration of 50 mg / ml, the solution was uniformly coated on the surface of a glass plate, and then the glass plate was heated to 60°C for 4 hours and to 120°C for 2 hours to obtain a polyimide film;
[0046] Step three: the polyimide film was heated to 300°C for 2 hours, to 380°C for 12 hours, and to 420°C for 24 hours for crosslinking, and then the film was cooled to room temperature to obtain a high-heat-resistant polyimide film with a crosslinked structure.
[0047] Example 4
[0048] Preparation of high-heat-resistant polyimide PI-4 film
[0049] Step one: 0.4974 g of p-phenylenediamine, 1.1209 g of 1,2,4,5-cyclohexane tetracarboxylic dianhydride, 0.1 g of 4-aminobenzonitrile, 0.15 ml of isoquinoline, and 15 ml of m-cresol were stirred and mixed, and then the mixture was reacted at room temperature for 2 hours under a nitrogen atmosphere, at 80°C for 4 hours, at 120°C for 4 hours, at 160°C for 24 hours, at 200°C for 48 hours, to obtain a polyimide solution, which was then precipitated in anhydrous ethanol, filtered, and dried to obtain polyimide powder;
[0050] Step two: the polyimide powder was dissolved in N,N-dimethylacetamide to form a solution with a concentration of 50 mg / ml, the solution was uniformly coated on the surface of a glass plate, and then the glass plate was heated to 60°C for 4 hours and to 120°C for 2 hours to obtain a polyimide film;
[0051] Step three: the polyimide film was heated to 300°C for 2 hours, to 380°C for 12 hours, and to 420°C for 24 hours for crosslinking, and then the film was cooled to room temperature to obtain a high-heat-resistant polyimide film with a crosslinked structure.
[0052] Example 5
[0053] Preparation of high-heat-resistant polyimide PI-5 film
[0054] Step one: 0.4948 g of 1,4-cyclohexanediamine, 2.2212 g of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, 0.21 g of 4-aminophthalonitrile, 0.15 ml of isoquinoline, and 15 ml of m-cresol were stirred and mixed, and then the mixture was reacted at room temperature for 2 hours under a nitrogen atmosphere, at 80°C for 4 hours, at 120°C for 4 hours, at 160°C for 24 hours, and at 200°C for 48 hours to obtain a polyimide solution, which was then precipitated in anhydrous ethanol, filtered, and dried to obtain polyimide powder;
[0055] Step two: the polyimide powder is mixed in nitrogen, nitrogen-dimethylacetamide to form a solution with a concentration of 50 mg / ml, the solution is uniformly coated on the surface of a glass plate, heated to 60°C for 4 hours, heated to 120°C for 2 hours, to obtain a polyimide film;
[0056] Step three: the polyimide film is heated to 300°C for 2 hours, heated to 380°C for 12 hours, heated to 420°C for 24 hours for crosslinking, and then cooled to room temperature to obtain a high-heat-resistant polyimide film with a crosslinked structure.
[0057] Example 6
[0058] Preparation of high-heat-resistant polyimide PI-6 film
[0059] Step one: 1,4-cyclohexanediamine 0.5253 g, 1,2,4,5-cyclohexanetetracarboxylic dianhydride 1.1209 g, 1-aminocyclohexane-1-carbonitrile 0.11 g, isoquinoline 0.15 ml, m-cresol 15 ml are weighed respectively and stirred and mixed, reacted at room temperature for 2 hours under nitrogen atmosphere, reacted at 60°C for 4 hours, heated to 100°C for 4 hours, heated to 140°C for 4 hours, heated to 180°C for 48 hours, heated to 200°C for 72 hours, to obtain a polyimide solution, then the polyimide is precipitated in anhydrous ethanol, filtered and dried to obtain polyimide powder;
[0060] Step two: the polyimide powder is mixed in nitrogen, nitrogen-dimethylacetamide to form a solution with a concentration of 50 mg / ml, the solution is uniformly coated on the surface of a glass plate, heated to 60°C for 4 hours, heated to 120°C for 2 hours, to obtain a polyimide film;
[0061] Step three: the polyimide film is heated to 300°C for 2 hours, heated to 380°C for 24 hours, heated to 420°C for 48 hours for crosslinking, and then cooled to room temperature to obtain a high-heat-resistant polyimide film with a crosslinked structure.
[0062] The above is only a preferred embodiment of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the disclosed technical range, which should be covered in the protection scope of the present application.
Claims
1. A method for preparing a high-temperature resistant polyimide film with end-group cross-linking, characterized in that: The steps include: Step 1: Weighing a diamine monomer, a dianhydride monomer, an end-capping monomer, and a catalyst respectively and dissolving them in a solvent, wherein the molar ratio of the diamine monomer to the dianhydride monomer is 0.7:1-0.95:1, the molar ratio of the end-capping monomer to the dianhydride monomer is 0.6:1-0.1:1, the weight percentage of the catalyst to the total monomers is 2.5-7.5%, and the concentration of the solution is 0.1-0.5 g / ml. The mixture is reacted at 20-60° C. under an inert gas atmosphere for 0.5-4 hours, at 60-120° C. for 0.5-4 hours, and then at 120-200° C. for 0.5-48 hours to obtain a polyimide solution, cooling the reaction solution and precipitating it in a precipitant, washing, filtering, and drying to obtain a polyimide powder product; Step 2: dissolving the polyimide prepared in step 1 or a mixture of polyimide and a curing catalyst in a solvent to obtain a polyimide solution, wherein the mass concentration of the polyimide in the solution is 1-10%; coating the obtained solution on a substrate, and maintaining the temperature in the range of 20-160° C. for 0.5-24 hours to obtain a polyimide film, wherein the coating method can be casting, spin coating, brush coating or doctor blade coating; Step 3: heating the polyimide film obtained in step 2 to 200-300° C. and maintaining it for 1-4 hours, then to 300-380° C. and maintaining it for 1-4 hours, and then further heating it to 380-420° C. and maintaining it for 4-12 hours to obtain a polyimide film with a cross-linked structure.
2. The method for preparing a high-temperature resistant polyimide film having a cross-linked structure according to claim 1, wherein: The diamine monomer in step 1 is one or a mixture of two or more of the following diamine compounds:
3. The method for preparing a high-temperature resistant polyimide film having a cross-linked structure according to claim 1, wherein the dianhydride monomer in step 1 is one or a mixture of two or more of the following compounds:
4. The method for preparing a high-temperature resistant polyimide film having a cross-linked structure according to claim 1, wherein the end-capping monoamine monomer in step 1 is one or a mixture of two or more of the following compounds:
5. The method for preparing a high-temperature resistant polyimide film having a cross-linked structure according to claim 1, wherein: The catalyst in step 1 is one or a mixture of two or more of the following compounds:
6. The method for preparing a high-temperature resistant polyimide film having a cross-linked structure according to claim 1, wherein: In step 1, the solvent is m-cresol and a mixture of m-cresol and one or more of halogenated hydrocarbons, nitrogen-methyl pyrrolidone, nitrogen, nitrogen-dimethylformamide, nitrogen, nitrogen-dimethylacetamide, and dimethyl sulfoxide; the precipitant is a mixture of one or more of alkanes, ethanol, methanol, and water.
7. The method for preparing a high-temperature resistant polyimide film having a cross-linked structure according to claim 1, wherein: The solvent in step 2 is one or a mixture of two or more of nitrogen-methylpyrrolidone, nitrogen-dimethylformamide, nitrogen-dimethylacetamide, and dimethyl sulfoxide.
8. The method for preparing a high-temperature resistant polyimide film having a cross-linked structure according to claim 1, wherein: The curing catalyst in step 2 is one or a mixture of two or more of ferric chloride, zinc chloride, cobalt acetylacetonate, ferric acetylacetonate, ethylenediamine, triethylamine, and aniline; the mass concentration of the curing catalyst in the system solution is 0-5%.
9. A high-temperature resistant polyimide film with a cross-linked structure obtained by the preparation method according to any one of claims 1 to 8.
10. Use of a high-temperature resistant polyimide film having a cross-linked structure obtained by the preparation method according to any one of claims 1 to 8, characterized in that: Application areas include aerospace, electronics and electrical appliances, machinery and automobiles.