Polyimide adhesive for high-temperature adhesion as well as preparation method and application of polyimide adhesive

Abstract

The invention relates to the technical field of high-molecular polymers, and particularly discloses a polyimide adhesive for high-temperature adhesion as well as a preparation method and application of the polyimide adhesive. The polyimide adhesive is prepared from the following raw materials in parts by mole: a diamine compound with a polyhydroxy structure, a flexible dianhydride compound, an organic solvent, a dehydrating agent and a catalyst, the preparation method comprises the following steps: dissolving a diamine compound in an organic solvent, adding a dianhydride compound, reacting to generate a polyimide precursor, adding a dehydrating agent and a catalyst, and reacting to generate the polyimide adhesive. The polyimide adhesive for high-temperature bonding can be applied to bonding of metal materials, ceramic materials and glass materials, and has the advantages of high bonding force, excellent high-temperature resistance, better chemical stability and capability of resisting acid and alkali erosion.

Description

Technical Field

[0001] This application relates to the technical field of polymers, and in particular to a polyimide adhesive for high-temperature bonding, its preparation method, and its application. Background Technology

[0002] Polyimide (PI) is a class of high-performance polymer materials with excellent thermal stability, electrical insulation, and mechanical properties, widely used in aerospace, electronics, and automotive industries. However, polyimide often faces insufficient adhesive performance in practical applications, especially under high-temperature environments or on complex material surfaces. Traditional polyimide adhesives exhibit poor adhesion in these applications, limiting their widespread use in high-end applications. Therefore, developing a polyimide adhesive with high adhesive performance, excellent high-temperature resistance, and reliability has significant research value and market demand.

[0003] Existing polyimide adhesives mostly rely on conventional adhesives such as epoxy resins and polyurethanes as base materials. While these adhesives can provide a certain level of bond strength, their high-temperature resistance, chemical stability, and performance degradation over long-term use remain significant shortcomings. Furthermore, the preparation process of these traditional adhesives is complex and costly, and their environmental adaptability is poor. Therefore, developing a new polyimide adhesive with high viscosity, adaptability to high-temperature working environments, and the ability to maintain excellent performance under extreme conditions has become a current research hotspot.

[0004] An ideal polyimide adhesive should possess the following characteristics: First, the adhesive should have high adhesion, especially strong adhesion to various substrates such as metals, ceramics, and glass; second, the adhesive should have excellent high-temperature resistance, enabling it to operate stably in high-temperature environments above 200°C; third, the adhesive needs to have good chemical stability, resisting the erosion of chemical media such as acids, alkalis, and solvents; finally, the adhesive's preparation process should be simple and cost-effective, facilitating its promotion in industrial applications.

[0005] However, most polyimide adhesives in the existing technology are based on rigid yellow PI. The raw materials of this type of PI material are PMDA, BPDA, BPADA, and 6FDA as dianhydride raw materials, and ODA, MDA, and phenylenediamine as diamine raw materials. These raw materials have been commercialized for a long time and are inexpensive, but the adhesive strength of the polyimide adhesives made from them is not strong and cannot meet the long-term use requirements of high adhesion.

[0006] Therefore, there is a need to develop a new high-viscosity polyimide adhesive that can not only meet the requirements for high bonding strength but also be used continuously at high temperatures to overcome the shortcomings of existing technologies. Summary of the Invention

[0007] To ensure that polyimide adhesives possess high adhesive strength, meeting the high-performance bonding requirements of metals, ceramics, and glass materials in aerospace, automotive, and electronics fields; they also need to exhibit excellent high-temperature resistance, functioning stably at temperatures above 200°C, and possess good chemical stability, resisting corrosion from acids, alkalis, solvents, and other chemical media. Furthermore, the adhesive preparation process must be simple and cost-effective for industrial application. This application provides a polyimide adhesive for high-temperature bonding, its preparation method, and its application.

[0008] In a first aspect, this application provides a polyimide adhesive for high-temperature bonding, employing the following technical solution:

[0009] A polyimide adhesive for high-temperature bonding, wherein the polyimide adhesive has the following structural formula:

[0010]

[0011] Where n is 2-1000;

[0012]

[0013] .

[0014] The excellent high-temperature resistance of the polyimide adhesive of this application, achieved by adopting the above technical solutions, is mainly due to its unique molecular structure and chemical properties. First, the polyimide molecule consists of rigid aromatic rings and strong covalent bonds. This structure enables it to maintain high stability at high temperatures, preventing thermal decomposition or deformation. Second, polyimide contains heat-resistant nitrogen-oxygen bonds, which are stronger than ordinary carbon-hydrogen bonds and can withstand higher temperatures. Its high thermal decomposition temperature (typically above 400℃) allows it to operate in extreme high-temperature environments. Third, the high degree of cross-linking of the polyimide polymer chain enhances its thermal stability and reduces changes in shape or performance caused by temperature variations. Finally, the low coefficient of thermal expansion of polyimide also helps it maintain its physical form and adhesive effect at high temperatures.

[0015] The superior acid and alkali resistance of the polyimide adhesive in this application compared to other adhesives is also attributed to its unique aromatic ring structure and strongly stable chemical bonds. The aromatic rings in the molecular chain provide strong chemical stability, effectively resisting acid and alkali corrosion. Furthermore, the presence of nitrogen-oxygen bonds gives polyimide strong corrosion resistance when exposed to acids and alkalis, avoiding the easy destruction of carbon-hydrogen or carbon-oxygen bonds in common adhesives. The high degree of cross-linking of the polyimide molecular chain also enhances its chemical stability, reducing the penetration of external substances.

[0016] Polyimide adhesives exhibit stronger adhesion to various substrates such as metals, ceramics, and glass. This is because the dianhydride monomer used in this application possesses a large number of hydroxyl (-OH) groups. Under polar conditions, the oxygen atoms in the hydroxyl groups carry a negative charge, and the hydrogen atoms carry a positive charge. These hydroxyl groups can form hydrogen bonds with the polar silicon-oxygen bonds on the silica surface. These hydrogen bonds create an attractive force between the polar polymer and the silica surface. Furthermore, hydroxyl groups often form on the silica surface of ceramics or glass, further interacting with the polyimide polymer and enhancing their bonding strength. Additionally, metals can form coordination bonds with hydroxyl groups, increasing interfacial interactions and thus improving adhesion.

[0017] Optionally, the polyimide adhesive is made from the following raw materials in weight percentages:

[0018] Diamine compounds with polyhydroxy structures and flexible dianhydride compounds, 5 wt%-35 wt%.

[0019] Organic solvents 60 wt%-90 wt%

[0020] Dehydrating agent 5 wt%-30 wt%,

[0021] Catalyst 0 wt%-3 wt%,

[0022] The molar ratio of the polyhydroxy diamine compound to the flexible dianhydride compound is (0.9-1.2):1.

[0023] Preferably, the molar ratio of the polyhydroxyl diamine compound to the flexible dianhydride compound can be 0.9:1, 0.95:1, 1:1, 1.05:1, 1.15:1, 1.2:1, etc.

[0024] Optionally, the mass percentage of the polyhydroxyl-structured diamine compound and the flexible dianhydride compound can be 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, etc., and the mass percentage of the organic solvent can be 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, etc. The mass percentage of the dehydrating agent can be 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, etc., and the mass percentage of the catalyst can be 0wt% (no catalyst is needed when the dehydrating agent is an inorganic dehydrating agent), 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, etc.

[0025] By adopting the above technical solution, the polyimide adhesive of this application is obtained by homopolymerization of a polyhydroxy diamine compound and a dianhydride compound containing flexible segments in an organic solvent. On the one hand, the diamine compound used in this application contains polyhydroxy groups and flexible segments, which enhances the polarity of the polymer segments, thereby improving the intermolecular forces between the polyimide adhesive and metals and glass. The flexible segments can improve the flexibility of the polymer. On the other hand, the dianhydride compound containing flexible segments can further improve the plasticity and flexibility of the polymer, enabling it to adapt to thermal expansion and contraction and improve the adaptability of the material. The flexible segments and aliphatic structure in the dianhydride molecule can increase the solubility of the polymer, which is beneficial for chemical imidization and material processing. Therefore, the polyamic acid adhesive of this application has excellent mechanical properties, high adhesion to metals, ceramics and glass, and high thermal properties, and can be used as a high-temperature resistant metal and glass bonding material or coating material.

[0026] Optionally, the diamine compound with a polyhydroxy structure includes 5,5'-methylenebis(2-aminophenol), 3-amino-5-[(3-amino-4,5-dihydroxyphenyl)methyl]benzene-1,2-diol, 3,3'-diamino-4,4'-dihydroxydiphenylmethane, 2,2-bis[(4-amino-3-hydroxy)phenyl]propane, 3-amino-5-[2-(3-amino-4,5-dihydroxyphenyl)propyl-2-yl]benzene-1,2- Diphenol, 2,2-bis(4-hydroxy-3-aminophenyl)propane, 3-amino-5-[(3-amino-4,5-dihydroxyphenyl)methyl]benzene-1,2-diphenol, 3,3'-[9H-fluorene-9-ylidenebis(4,1-phenoxy)]bis[6-amino-phenol, 3-amino-5-[2-(3-amino-4,5-dihydroxyphenyl)prop-2-yl]benzene-1,2-diphenol, 2-amino-5-{[4-(9-{4-[(4 -amino-3,5-dihydroxyphenyl)oxy]phenyl}-9H-fluoren-9-yl)phenyl]oxy}benzene-1,3-diphenol, 2-amino-5-{[4-(2-{4-[(4-amino-3-hydroxyphenyl)oxy]phenyl}prop-2-yl)phenyl]oxy}phenol, 2-amino-5-{[4-({4-[(4-amino-3,5-dihydroxyphenyl)oxy]phenyl}methyl)phenyl]oxy}benzene-1,3-diphenol, 2-amino One or more of -5-{[4-(2-{4-[(4-amino-3-hydroxyphenyl)oxy]phenyl}-1,1,1,3,3,3-hexafluoroprop-2-yl)phenyl]oxy}phenol and 2-amino-5-{[4-(2-{4-[(4-amino-3,5-dihydroxyphenyl)oxy]phenyl}-1,1,1,3,3,3-hexafluoroprop-2-yl)phenyl]oxy}phenyl-1,3-diol, have the following structural formulas:

[0027] .

[0028] By adopting the above technical solution, the dianhydride compound used in this application has a large number of hydroxyl (-OH) groups. Under polar conditions, the oxygen atoms in the hydroxyl groups carry a negative charge, and the hydrogen atoms carry a positive charge. These hydroxyl groups can form hydrogen bonds with the polar silicon-oxygen bonds on the silica surface. This hydrogen bonding creates an attractive force between the polar polymer and the silica surface. Furthermore, hydroxyl groups often form on the silica surface, further interacting with the polymer and enhancing their bonding strength, thus further strengthening the adhesive force of the polyimide adhesive.

[0029] Optionally, the flexible dianhydride compound includes 5-{[4-(2-{4-[(1,3-dioxonyl-1,3-dihydro-2-benzofuran-5-yl)oxy]phenyl}-1,1,1,3,3,3-hexafluoroprop-2-yl)phenyl]oxy}-2-benzofuran-1,3-dione, bisphenol A type diether dianhydride, N,N'-(2,2-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(1,3-disidel-oxy-1,3-dihydroisobenzofuran-5-carboxyamide), 4-(4-{[(1,3-dioxonyl-1,3-dihydro-2-benzofuran-5-yl)oxy]carbonyl}-2-(trifluoromethyl) One or more of the following are listed below: phenyl)-3-(trifluoromethyl)benzoic acid-1,3-dioxane-1,3-dihydrofurano[3,4-a]phenyl-5-yl ester, 4,4'-oxobisphthalic anhydride, 3,4'-oxobisphthalic anhydride, 11H-difurano[4,3-b:4',3'-i]xanthon-1,3,7,9-tetraone, 11,11-dimethyl-11H-difurano[4,3-i:4',3'-b]xanthon-1,3,7,9-tetraone, and 11,11'-bis(trifluoromethyl)-11H-difurano[4,3-b:4',3'-i]xanthon-1,3,7,9-tetraone.

[0030] .

[0031] By adopting the above technical solution, the use of the above-mentioned dianhydride compound containing flexible segments can not only further improve the plasticity and flexibility of the polymer, enabling it to adapt to thermal expansion and contraction and improve the adaptability of the material, but also the flexible segments and aliphatic structure in the dianhydride molecule can increase the solubility of the polymer, which is beneficial to chemical imidization and material processing.

[0032] Optionally, the organic solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, γ-butyrolactone, dimethyl sulfoxide, butanone, and m-cresol.

[0033] Optionally, the dehydrating agent includes one or more of 4A molecular sieve, aluminum chloride, calcium chloride, phosphorus pentafluoride, disulfide decafluoride, acetic anhydride, and tetrafluoroethylene anhydride.

[0034] Optionally, the catalyst comprises one or more of pyridine, 4-dimethylaminopyridine, quinoline, isoquinoline, N-methylmorpholine, imidazole, N-methylimidazolium, 1,2-dimethylimidazolium, and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0035] Secondly, this application provides a method for preparing a polyimide adhesive for high-temperature bonding, employing the following technical solution:

[0036] A method for preparing a polyimide adhesive for high-temperature bonding includes the following steps:

[0037] The diamine compound with the polyhydroxy structure is dissolved in an organic solvent and stirred until dissolved. Then, the flexible dianhydride compound is added at a reaction temperature of -30 to 150°C, and a polyimide precursor is generated through an amide condensation reaction. A dehydrating agent and a catalyst are added at a reaction temperature of -30 to 150°C and a stirring rate of 50 to 500 rpm, and a polyimide adhesive is generated through a dehydration cyclization reaction.

[0038] By adopting the above technical solution, a polyamic acid precursor is obtained by amide condensation reaction of a diamine compound and a dianhydride compound. After dehydration and cyclization by the combined action of a dehydrating agent and a catalyst, a polyimide adhesive is obtained.

[0039] Preferably, the reaction temperature is -20~50℃, and the stirring rate is 50-200rpm. Specifically, the reaction temperature can be -20℃, -15℃, -10℃, -5℃, -3℃, 0℃, 1℃, 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, or 50℃, and the stirring rate can be 50rpm, 60rpm, 70rpm, 80rpm, 90rpm, 100rpm, 110rpm, 120rpm, 130rpm, 140rpm, 150rpm, 160rpm, 170rpm, 180rpm, 190rpm, or 200rpm.

[0040] Thirdly, this application provides an application of a polyimide adhesive for high-temperature bonding, employing the following technical solution:

[0041] An application of a polyimide adhesive for high-temperature bonding, wherein the polyimide adhesive described above for high-temperature bonding is applied to the bonding of metal materials, ceramic materials or glass materials.

[0042] In summary, this application has the following beneficial effects:

[0043] 1. The excellent high-temperature resistance of the polyimide adhesive of this application is mainly due to its unique molecular structure and chemical properties. First, the polyimide molecule is composed of rigid aromatic rings and strong covalent bonds. This structure enables it to maintain high stability at high temperatures, avoiding thermal decomposition or deformation. Second, polyimide contains heat-resistant nitrogen-oxygen bonds, which are stronger than ordinary carbon-hydrogen bonds and can withstand higher temperatures. Its high thermal decomposition temperature (typically above 400℃) allows it to operate in extreme high-temperature environments. Third, the high degree of cross-linking of the polyimide polymer chain enhances its thermal stability and reduces changes in shape or performance due to temperature variations. Finally, the low coefficient of thermal expansion of polyimide also helps it maintain its physical form and adhesive effect at high temperatures.

[0044] The superior acid and alkali resistance of the polyimide adhesive in this application compared to other adhesives is also attributed to its unique aromatic ring structure and strongly stable chemical bonds. The aromatic rings in the molecular chain provide strong chemical stability, effectively resisting acid and alkali corrosion. Furthermore, the presence of nitrogen-oxygen bonds gives polyimide strong corrosion resistance when exposed to acids and alkalis, avoiding the easy destruction of carbon-hydrogen or carbon-oxygen bonds in common adhesives. The high degree of cross-linking of the polyimide molecular chain also enhances its chemical stability, reducing the penetration of external substances.

[0045] The reason why polyimide adhesives exhibit stronger adhesion to various substrates such as metals and glass is that the dianhydride monomer used in this application has a large number of hydroxyl (-OH) groups. Under polar conditions, the oxygen atoms in the hydroxyl groups carry a negative charge, and the hydrogen atoms carry a positive charge. These hydroxyl groups can form hydrogen bonds with the polar silicon-oxygen bonds on the silica surface. These hydrogen bonds create an attractive force between the polar polymer and the silica surface. Furthermore, hydroxyl groups often form on silica surfaces such as metals or glass, further interacting with the polyimide polymer and enhancing their bonding strength.

[0046] 2. The polyimide adhesive of this application is obtained by homopolymerization of a polyhydroxy diamine compound and a dianhydride compound containing flexible segments in an organic solvent. On the one hand, the diamine compound used in this application contains polyhydroxy groups and flexible segments, which enhances the polarity of the polymer segments, thereby improving the intermolecular forces between the polyimide adhesive and metals and glass. The flexible segments can improve the flexibility of the polymer. On the other hand, the dianhydride compound containing flexible segments can further improve the plasticity and flexibility of the polymer, enabling it to adapt to thermal expansion and contraction and improve the adaptability of the material. The flexible segments and aliphatic structure in the dianhydride molecule can increase the solubility of the polymer, which is beneficial for chemical imidization and material processing. Therefore, the polyamic acid adhesive of this application has excellent mechanical properties, high adhesion to metal and glass materials, and high thermal properties, and can be used as a high-temperature resistant metal and glass bonding material or coating material.

[0047] 3. The synthesis process is simple, safe, and yields high results, reducing production costs and risks, lowering requirements for reaction equipment, and facilitating industrial production. The resulting high-adhesion polyimide material is particularly suitable for achieving high-performance bonding of metals and glass materials in aerospace, automotive, and electronics industries. Attached Figure Description

[0048] Figure 1 This is a picture of an adhesive being used on ceramic components.

[0049] Figure 2 This is a picture of an adhesive being applied to glass components.

[0050] Figure 3 This is a picture of an adhesive being used on a metal part. Detailed Implementation

[0051] Experimental methods in the following embodiments of this application that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the embodiments are commercially available products.

[0052] Raw material source:

[0053] The following disclosure of raw material sources is for clarity only and should not limit the scope of protection.

[0054]

[0055]

[0056]

[0057]

[0058]

[0059] Example 1

[0060] A high-performance polyimide adhesive for high-temperature bonding is prepared from the following raw materials by weight:

[0061] A total of 15g of diamine compound and dianhydride compound;

[0062] 60g of organic solvent;

[0063] 5g of dehydrating agent;

[0064] Catalyst 0.5g;

[0065] The molar ratio of the diamine compound to the dianhydride compound is 1:1.

[0066] The diamine compound is 5,5'-methylenebis(2-aminophenol), the dianhydride compound is 5-{[4-(2-{4-[(1,3-dioxane-1,3-dihydro-2-benzofuran-5-yl)oxy]phenyl}-1,1,1,3,3,3-hexafluoroprop-2-yl)phenyl]oxy}-2-benzofuran-1,3-dione, the organic solvent is N-methylpyrrolidone, the dehydrating agent is acetic anhydride, and the catalyst is pyridine.

[0067] A method for preparing a high-performance polyimide adhesive for high-temperature bonding includes the following steps:

[0068] (1) Preparation of polyimide precursor (polyamic acid)

[0069] 5,5'-methylenebis(2-aminophenol) was added to a 500 mL four-necked jacketed reaction flask, followed by a portion of N-methylpyrrolidone. The stirrer was turned on and stirred until the diamine compound was completely dissolved. The system was cooled to 0°C, and 5-{[4-(2-{4-[(1,3-dioxane-1,3-dihydro-2-benzofuran-5-yl)oxy]phenyl}-1,1,1,3,3,3-hexafluoroprop-2-yl)phenyl]oxy}-2-benzofuran-1,3-dione was slowly added. Subsequently, the remaining N-methylpyrrolidone was slowly added to the reaction system, with the system temperature controlled at 0-5°C during the addition process. After the addition was completed, the system temperature was controlled at 0-5°C and the reaction was stirred for 24 h. After the reaction was completed, a polyamic acid solution suitable for high-temperature bonding was obtained.

[0070] (2) Preparation of polyimide

[0071] Maintaining the system temperature at 0-5℃, acetic anhydride was added to the polyamic acid solution as a dehydrating agent, and the mixture was stirred for 30 min. Then, pyridine was added as a catalyst, and the stirring rate was 100 rpm. Subsequently, the system temperature was controlled at 25-30℃, and the reaction was stirred for 24 h. After the reaction was complete, a polyimide solution suitable for high-temperature bonding was obtained.

[0072] Example 2-3

[0073] A high-performance polyimide adhesive for high-temperature bonding differs from Example 1 in that the molar ratio of the diamine compound and the dianhydride compound is different, as detailed in Table 1.

[0074] Table 1. Raw material ratios for Examples 1-3

[0075]

[0076] Example 4

[0077] A high-performance polyimide adhesive for high-temperature bonding differs from Example 1 in that the diamine compound is 3-amino-5-[(3-amino-4,5-dihydroxyphenyl)methyl]benzene-1,2-diol, and the dianhydride compound is bisphenol A type diether dianhydride; all other aspects are the same.

[0078] Example 5

[0079] A high-performance polyimide adhesive for high-temperature bonding differs from Example 1 in that the diamine compound is 3,3'-diamino-4,4'-dihydroxydiphenylmethane, and the dianhydride compound is N,N'-(2,2-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(1,3-disideloxy-1,3-dihydroisobenzofuran-5-carboxyamide), all other parts being the same.

[0080] Example 6

[0081] A high-performance polyimide adhesive for high-temperature bonding differs from Example 1 in that the diamine compound is 2,2-bis[(4-amino-3-hydroxy)phenyl]propane, the dianhydride compound is 4-(4-{[(1,3-dioxonyl-1,3-dihydro-2-benzofuran-5-yl)oxy]carbonyl}-2-(trifluoromethyl)phenyl)-3-(trifluoromethyl)benzoic acid-1,3-dioxonyl-1,3-dihydrofuran[3,4-a]phenyl-5-yl ester, and the rest are the same.

[0082] Example 7

[0083] A high-performance polyimide adhesive for high-temperature bonding differs from Example 1 in that the diamine compound is 3-amino-5-[2-(3-amino-4,5-dihydroxyphenyl)prop-2-yl]phenyl-1,2-diol, and the dianhydride compound is 4,4'-oxobisphthalic anhydride; all other aspects are the same.

[0084] Example 8

[0085] A high-performance polyimide adhesive for high-temperature bonding differs from Example 1 in that, based on the total amount of diamine compounds, the diamine compounds are 2,2-bis(4-hydroxy-3-aminophenyl)propane and 3-amino-5-[(3-amino-4,5-dihydroxyphenyl)methyl]benzene-1,2-diol in a molar ratio of 1:9, the dianhydride compound is 3,4'-oxobisphthalic anhydride, the molar ratio between the diamine compounds and the dianhydride compounds is 1:1, and all other aspects are the same.

[0086] Example 9

[0087] A high-performance polyimide adhesive for high-temperature bonding differs from Example 1 in that, based on the total amount of diamine compounds, the diamine compounds are 3,3'-[9H-fluorene-9-ylidenebis(4,1-phenoxy)]bis[6-amino-phenol and 3-amino-5-[2-(3-amino-4,5-dihydroxyphenyl)prop-2-yl]phenyl-1,2-diol in a molar ratio of 9:1, the dianhydride compound is 11H-difurano[4,3-b:4',3'-i]xanthon-1,3,7,9-tetraone, the molar ratio between the diamine compounds and the dianhydride compounds is 1:1, and all other aspects are the same.

[0088] Example 10

[0089] A high-performance polyimide adhesive for high-temperature bonding differs from Example 1 in that, based on the total amount of diamine compounds, the diamine compounds are 2-amino-5-{[4-(9-{4-[(4-amino-3,5-dihydroxyphenyl)oxy]phenyl}-9H-fluorene-9-yl)phenyl]oxy}benzene-1,3-diphenol and 2-amino-5-{[4-(2-{4-[(4-amino-3-hydroxyphenyl)oxy]phenyl}prop-2-yl)phenyl]oxy}phenol in a molar ratio of 2:8, the dianhydride compound is 11,11-dimethyl-11H-difurano[4,3-i:4',3'-b]xanthon-1,3,7,9-tetraone, the molar ratio between the diamine compounds and the dianhydride compounds is 1:1, and all other aspects are the same.

[0090] Example 11

[0091] A high-performance polyimide adhesive for high-temperature bonding differs from Example 1 in that, based on the total amount of diamine compounds, the diamine compounds are 2-amino-5-{[4-({4-[(4-amino-3,5-dihydroxyphenyl)oxy]phenyl}methyl)phenyl]oxy}benzene-1,3-diphenol and 2-amino-5-{[4-(2-{4-[(4-amino-3-hydroxyphenyl)oxy]phenyl}-1,1,1,3,3,3-hexafluoroprop-2-yl)phenyl]oxy}phenol in a molar ratio of 8:2, the dianhydride compound is 11,11'-bis(trifluoromethyl)-11H-difurano[4,3-b:4',3'-i]xanthon-1,3,7,9-tetraone, the molar ratio between the diamine compounds and the dianhydride compounds is 1:1, and all other aspects are the same.

[0092] Example 12

[0093] A high-performance polyimide adhesive for high-temperature bonding differs from Example 1 in that the dehydrating agent is 4A molecular sieve and there is no catalyst (when the dehydrating agent is an inorganic dehydrating agent, no catalyst is required), but all other aspects are the same.

[0094] Example 13

[0095] A high-performance polyimide adhesive for high-temperature bonding differs from Example 1 in that the dehydrating agent is tetrafluoroethylene anhydride and the catalyst is 1,2-dimethylimidazole, while the rest are the same.

[0096] Comparative Example 1

[0097] A polyimide adhesive, differing from Example 1 in that an equal amount of p-phenylenediamine is used instead of 5,5'-methylenebis(2-aminophenol), otherwise the same.

[0098] Comparative Example 2

[0099] A polyimide adhesive differs from Example 1 in that an equal amount of pyromellitic dianhydride is used to replace 5-{[4-(2-{4-[(1,3-dioxane-1,3-dihydro-2-benzofuran-5-yl)oxy]phenyl}-1,1,1,3,3,3-hexafluoroprop-2-yl)phenyl]oxy}-2-benzofuran-1,3-dione, all other aspects are the same.

[0100] Comparative Example 3

[0101] A polyimide adhesive differs from Example 1 in that it uses 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) as the dianhydride compound and 4,4'-oxodiphenylamine (ODA) as the diamine compound, while all other aspects are the same.

[0102] Performance testing

[0103] 1. Performance testing of ceramic devices using polyimide adhesives

[0104] like Figure 1 As shown, the polyimide adhesives prepared in Examples 1-13 and Comparative Examples 1-2 were applied to the ceramic devices to be bonded, respectively, and pre-cured at 120°C for 10 min. The devices were then removed, covered with another ceramic device to be bonded, and cured again in an oven at 120°C for 1 h to obtain bonded devices. The bonding strength of the ceramic devices at room temperature and at 200°C was tested (refer to GB / T 7124-2008). The test results are shown in Table 2.

[0105] 2. Performance testing of glass devices using polyimide adhesives

[0106] like Figure 2 As shown, the polyimide adhesives prepared in Examples 1-13 and Comparative Examples 1-2 were applied to the glass devices to be bonded, respectively, and pre-cured at 120°C for 10 min. The devices were then removed, covered with another glass device to be bonded, and cured again in an oven at 120°C for 1 h to obtain bonded devices. The bonding strength of the glass devices at room temperature and at 200°C was tested (refer to GB / T 7124-2008). The test results are shown in Table 3.

[0107] 3. Performance testing of polyimide adhesives for metal parts

[0108] like Figure 3 As shown, the polyimide adhesives prepared in Examples 1-13 and Comparative Examples 1-2 were applied to the metal components to be bonded, and pre-cured at 120°C for 10 min. The components were then removed, covered with another metal component to be bonded, and cured again in an oven at 120°C for 1 h to obtain the bonded components. The bonding strength of the metal components at room temperature and at 200°C (GB / T 7124-2008) were tested, and the test results are shown in Table 4.

[0109] 4. Acid and alkali resistance test of polyimide adhesive

[0110] The polyimide adhesives prepared in Examples 7-11 were tested for their performance under acid and alkaline chemical erosion (refer to ASTM D543-20), and the test results are shown in Table 5.

[0111] Table 2 Test results of adhesives applied to ceramic devices

[0112]

[0113] Table 3 Test results of adhesives applied to glass devices

[0114]

[0115] Table 4 Test results of adhesives applied to metal parts

[0116]

[0117] Table 5 Results of acid and alkali resistance tests of adhesives

[0118]

[0119] Combining the test results of Examples 1-11 and Comparative Examples 1-2 with those in Tables 2-4, it can be seen that Examples 1-11 are superior to Comparative Examples 1-2. The reason for this is that the polyimide adhesive of this application exhibits excellent high-temperature resistance, mainly due to its unique molecular structure and chemical properties. First, the polyimide molecule is composed of rigid aromatic rings and strong covalent bonds. This structure enables it to maintain high stability at high temperatures, avoiding thermal decomposition or deformation. Second, polyimide contains heat-resistant nitrogen-oxygen bonds, which are stronger than ordinary carbon-hydrogen bonds and can withstand higher temperatures. Its high thermal decomposition temperature (typically above 400°C) allows it to operate in extreme high-temperature environments. Third, the high degree of cross-linking of the polyimide polymer chain enhances its thermal stability and reduces changes in shape or performance caused by temperature variations. Finally, the low coefficient of thermal expansion of polyimide also helps it maintain its physical form and adhesive effect at high temperatures.

[0120] The reason why polyimide adhesives exhibit stronger adhesion to various substrates such as metals, glass, and ceramics is due to the large number of hydroxyl (-OH) groups in the dianhydride monomer used in this application. Under polar conditions, the oxygen atoms in the hydroxyl groups carry a negative charge, and the hydrogen atoms carry a positive charge, enabling them to form hydrogen bonds with the polar silicon-oxygen bonds on the silica surface. These hydrogen bonds create an attractive force between the polar polymer and the silica surface. Furthermore, hydroxyl groups often form on the silica surface of ceramics or glass, further interacting with the polyimide polymer and enhancing their bonding strength. Additionally, metals can form coordination bonds with hydroxyl groups, increasing the interfacial interaction forces and thus improving adhesive strength.

[0121] As can be seen from Examples 7-11 and Table 5, Examples 7-11, in addition to exhibiting good adhesive strength as preferred embodiments, also demonstrate excellent acid and alkali resistance. The reason for this is that the acid and alkali resistance of the polyimide adhesive of this application benefits from its unique aromatic ring structure and strongly stable chemical bonds. The aromatic rings in the molecular chain provide strong chemical stability, effectively resisting acid and alkali corrosion. Furthermore, the presence of nitrogen-oxygen bonds gives polyimide strong corrosion resistance when facing acids and alkalis, avoiding the easy destruction of carbon-hydrogen or carbon-oxygen bonds in common adhesives. The high degree of cross-linking of the polyimide molecular chain also enhances its chemical stability, reducing the penetration of external substances.

[0122] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A polyimide adhesive for high temperature bonding, characterized by: The structural formula of the polyimide adhesive is as follows: ； Wherein, n is 2-1000; ； 。 2. The polyimide adhesive for high temperature bonding according to claim 1, characterized by: The polyimide adhesive is made of the following raw materials in mass percentage: Diamine compound with polyhydroxy structure and flexible dianhydride compound 5 wt%-35 wt%, Organic solvent 60 wt%-90 wt%, Dehydrating agent 5 wt%-30 wt%, Catalyst 0 wt%-3 wt%, Wherein, the molar ratio of the diamine compound with polyhydroxy structure and the flexible dianhydride compound is (0.9-1.2):

1.

3. The polyimide adhesive for high temperature bonding according to claim 2, characterized by: The diamine compound with polyhydroxy structure includes one or more of 5,5'-methylenebis(2-aminophenol), 3-amino-5-[(3-amino-4,5-dihydroxyphenyl)methyl]benzene-1,2-diol, 3,3'-diamino-4,4'-dihydroxydiphenylmethane, 2,2-bis[(4-amino-3-hydroxy)phenyl]propane, 3-amino-5-[2-(3-amino-4,5-dihydroxyphenyl)prop-2-yl]benzene-1,2-diol, 2,2-bis(4-hydroxy-3-aminophenyl)propane, 3-amino-5-[(3-amino-4,5-dihydroxyphenyl)methyl]benzene-1,2-diol, 3,3'-[9H-fluoren-9-ylidenebis(4,1-phenoxy)]bis[6-amino-phenol, 3-amino-5-[2-(3-amino-4,5-dihydroxyphenyl)prop-2-yl]benzene-1,2-diol, 2-amino-5-{[4-(9-{4-[(4-amino-3,5-dihydroxyphenyl)oxy]phenyl}-9H-fluoren-9-yl)phenyl]oxy}benzene-1,3-diol, 2-amino-5-{[4-(2-{4-[(4-amino-3-hydroxyphenyl)oxy]phenyl}prop-2-yl)phenyl]oxy}phenol, 2-amino-5-{[4-({4-[(4-amino-3,5-dihydroxyphenyl)oxy]phenyl}methyl)phenyl]oxy}benzene-1,3-diol, 2-amino-5-{[4-(2-{4-[(4-amino-3-hydroxyphenyl)oxy]phenyl}-1,1,1,3,3,3-hexafluoropropan-2-yl)phenyl]oxy}phenol, and 2-amino-5-{[4-(2-{4-[(4-amino-3,5-dihydroxyphenyl)oxy]phenyl}-1,1,1,3,3,3-hexafluoropropan-2-yl)phenyl]oxy}benzene-1,3-diol, the structural formula of which is shown as follows in sequence: 。 4. The polyimide adhesive for high temperature bonding according to claim 2, characterized by: The flexible dianhydride compounds include 5-{[4-(2-{4-[(1,3-dioxonyl-1,3-dihydro-2-benzofuran-5-yl)oxy]phenyl}-1,1,1,3,3,3-hexafluoroprop-2-yl)phenyl]oxy}-2-benzofuran-1,3-dione, bisphenol A type diether dianhydride, N,N'-(2,2-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(1,3-disidel-1,3-dihydroisobenzofuran-5-carboxylamide), 4-(4-{[(1,3-dioxonyl-1,3-dihydro-2-benzofuran-5-yl)oxy]carbonyl}-2-(trifluoromethyl)benzene The structural formulas of one or more of the following are given: 1,3-dioxoylide-1,3-dihydrofurano[3,4-a]phenyl-5-yl ester, 4,4'-oxobisphthalic anhydride, 3,4'-oxobisphthalic anhydride, 11H-difurano[4,3-b:4',3'-i]xanthon-1,3,7,9-tetraone, 11,11-dimethyl-11H-difurano[4,3-i:4',3'-b]xanthon-1,3,7,9-tetraone, and 11,11'-bis(trifluoromethyl)-11H-difurano[4,3-b:4',3'-i]xanthon-1,3,7,9-tetraone. 。 5. The polyimide adhesive for high temperature bonding according to claim 2, characterized by: The organic solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, γ-butyrolactone, dimethyl sulfoxide, butanone, and m-cresol.

6. The polyimide adhesive for high temperature bonding according to claim 2, characterized by: The dehydrating agent includes one or more of the following: 4A molecular sieve, aluminum chloride, calcium chloride, phosphorus pentafluoride, disulfide decafluoride, acetic anhydride, and tetrafluoroethylene anhydride.

7. The polyimide adhesive for high temperature bonding according to claim 2, characterized by: The catalyst comprises one or more of pyridine, 4-dimethylaminopyridine, quinoline, isoquinoline, N-methylmorpholine, imidazole, N-methylimidazolium, 1,2-dimethylimidazolium, and 1,8-diazabicyclo[5.4.0]undec-7-ene.

8. A method for producing the polyimide adhesive for high temperature bonding according to any one of claims 1 to 7, characterized by, Includes the following steps: The diamine compound with the polyhydroxy structure is dissolved in an organic solvent and stirred until dissolved. Then, the flexible dianhydride compound is added at a reaction temperature of -30 to 150°C, and a polyimide precursor is generated through an amide condensation reaction. A dehydrating agent and a catalyst are added at a reaction temperature of -30 to 150°C and a stirring rate of 50 to 500 rpm, and a polyimide adhesive is generated through a dehydration cyclization reaction.

9. Use of a polyimide adhesive for high temperature bonding, characterized in that The polyimide adhesive for high-temperature bonding according to any one of claims 1-7 is applied to the bonding of metal, ceramic or glass materials.

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