Polyamide material, preparation method and application thereof and polyamide membrane

Abstract

The invention relates to a polyamide material, a preparation method and application thereof and a polyamide membrane. The polyamide material has a main chain structure and a connecting structure for crosslinking the main chain structure, wherein the main chain structure comprises a first structural unit formed by a first aromatic diacid monomer, a second structural unit formed by a second aromatic diacid monomer, a third structural unit formed by a first aromatic diamine monomer and a fourth structural unit formed by a phenolic hydroxyl group-containing second aromatic diamine monomer; the connecting structure is formed by carrying out polymerization reaction on aromatic diisocyanate and phenolic hydroxyl groups in the fourth structural unit. The polyamide material has balanced thermodynamic properties and transparency, meets the performance requirements of being colorless, transparent and resistant to high temperature, can be used for flexible printed circuit boards, and has wide application prospects in the fields of transparent display screens, touch equipment, vehicle-mounted screens, health sensors, intelligent windows and the like. And particularly, the method has wide application prospects in the industries of consumer electronics, unmanned aerial vehicles, intelligent robots and new energy automobiles.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a kind of polyamide material, the method for preparing the polyamide material, and the application of the polyamide material and polyamide film. BACKGROUND

[0002] Colorless transparent high-temperature-resistant polyamide (CPPA) is another kind of high-performance polymeric material, which is known for its high heat resistance and glass transition temperature similar to polyimide. It is also a relatively low-cost material among transparent plastic substrates that can meet the application requirements of flexible display and other applications. Its excellent performance is due to strong and highly directional interchain hydrogen bonds, which result in high cohesive energy between polymer chains. However, due to the strong interaction between rigid aromatic chains and multiple hydrogen bonds, they are difficult to handle and insoluble in organic solvents. The current industry chain application mainly needs to solve the problems of poor resin solubility, poor processability, relatively low mechanical properties and temperature resistance of thin films, and relatively high haze.

[0003] Currently, high-transparency polyamides have been industrialized abroad, such as Germany's Trogamid T series transparent nylon, Germany's Durethan T40 transparent nylon, Japan's Mitsubishi Chemical's Novamid X21 transparent nylon, America's DuPont Selar PA-3426 transparent nylon, and Switzerland's Grivory G21 transparent nylon. The development of transparent polyamides in China is relatively late, and high-quality transparent polyamides still need to rely heavily on imports. Currently, only a few examples of optically transparent polyamides have been studied, and the existing colorless transparent high-temperature-resistant polyamide film has certain gaps in tensile strength mechanics, heat resistance, and haze optical performance indicators compared to colorless transparent polyimide (CPI) and colorless transparent polyamide-imide (CPAI) films. It cannot fully meet the needs of thin-film transistors (TFT), transparent crystal film screens, and other flexible display substrates.

[0004] Therefore, there is an urgent need to develop a colorless transparent high-temperature-resistant polyamide film material that can be applied to flexible substrates. SUMMARY

[0005] To solve the problems of easy gelation of polymerization, low solid content of film-forming slurry and low mechanical and thermal properties of CPPA film caused by poor solubility of the CPPA resin, the polyamide material provided by the present application has a main chain structure and a connecting structure for cross-linking the main chain structure.

[0006] According to one aspect, a polyamide material is provided, having a main chain structure, and a connecting structure for cross-linking the main chain structure; wherein the main chain structure comprises a first structural unit formed by a first aromatic diacid monomer a second structural unit formed by a second aromatic diacid monomer a third structural unit formed by a first aromatic diamine monomer and a fourth structural unit formed by a second aromatic diamine monomer containing phenolic hydroxyl group. wherein Ar1 and Ar5 are independently connected by one or more groups selected from phenylene, -O-, biphenylene, -C(=O)-, C 1-4 alkylene and sulfone, and the phenylene, biphenylene and C 1-4 alkylene are optionally substituted by one or more substituents selected from C 1-4 alkyl (preferably methyl, tert-butyl), halo-C 1-4 alkyl (preferably trifluoromethyl), halogen (preferably -Cl), substituted or unsubstituted phenyl and substituted or unsubstituted naphthyl, wherein the phenyl and naphthyl are optionally substituted by one or more substituents selected from C 1-4 alkyl (preferably methyl, tert-butyl), halo-C 1-4 alkyl (preferably trifluoromethyl) and halogen (preferably -Cl); Ar2 is connected by one or more groups selected from phenylene, -O-, biphenylene, -NH-, -C(=O)-, -S-, C 1-4 alkylene, C 3-4 cycloalkylene and sulfone, and the phenylene, biphenylene, C 1-4 alkylene and C 3-4 cycloalkylene are optionally substituted by one or more substituents selected from C 1-4 alkyl (preferably methyl, tert-butyl), halo-C 1-4 ​alkyl (preferably trifluoromethyl), halogen (preferably -F), substituted or unsubstituted fluorenyl, and substituted or unsubstituted phenyl, the phenyl and fluorenyl groups here being optionally substituted with one or more substituents selected from the group consisting of C 1-4 alkyl (preferably methyl), haloC 1-4 alkyl (preferably trifluoromethyl), and halogen (preferably -F). Ar3 is formed by one or more groups selected from the group consisting of tetra-substituted phenylene, -0-, tetra-substituted biphenylene, di-substituted phenylene, -NH-, -C(=0)-, C 1-4 alkylene, sulfone, and pyridylene, the tetra-substituted phenylene, tetra-substituted biphenylene, di-substituted phenylene, and C 1-4 alkylene is optionally substituted with one or more substituents selected from the group consisting of C 1-4 alkyl (preferably methyl), haloC 1-4 alkyl (preferably trifluoromethyl), halogen (preferably -F), and substituted or unsubstituted phenyl, the phenyl here being optionally substituted with one or more substituents selected from the group consisting of C 1-4 alkyl (preferably methyl, t-butyl), haloC 1-4 alkyl (preferably trifluoromethyl), and halogen (preferably -F). the linking structure is formed by polymerization reaction of an aromatic diisocyanate with the phenolic hydroxyl group in the fourth structural unit.

[0007] According to one preferred embodiment, the linking structure is represented by Formula II: Formula II, wherein Ar4 is formed by one or more groups selected from the group consisting of phenylene, naphthylene, C 1-4 alkylene, and C 3-6 cycloalkylene, wherein phenylene, naphthylene, C 1-4 alkylene, and C 3-6 cycloalkylene is optionally substituted with one or more substituents selected from the group consisting of C 1-4 alkyl (preferably methyl), haloC 1-4 alkyl (preferably trifluoromethyl), and halogen (preferably -F).

[0008] According to one preferred embodiment, Ar1 and Ar5 are independently selected from one or more of the following structures: .

[0010] According to one preferred embodiment, Ar2 is selected from one or more of the following structures: .

[0011] According to one preferred embodiment, Ar3 is selected from one or more of the following structures:

[0012] wherein, denotes the position at which Ar3is attached to the N atom, denotes the position at which Ar3is attached to the O atom.

[0013] According to one preferred embodiment, Ar4is selected from one or more of the following structures: -C x H 2x - wherein x is an integer from 1 to 6;

[0014] .

[0016] According to one preferred embodiment, the first and second aromatic diacid monomers are independently selected from one or more of the following: terephthalic acid, 4,4'-biphenyldicarboxylic acid, 2,5-dichloroterephthalic acid, 2,2'-biphenyldicarboxylic acid, 2-trifluoromethylterephthalic acid, 2-methylterephthalic acid, isophthalic acid, 2,2'-bis(trifluoromethyl)-4,4'-biphenyldicarboxylic acid, 2-methyl-4,4'-biphenyldicarboxylic acid, 2-trifluoromethyl-4,4'-biphenyldicarboxylic acid, 2-tert-butylisophthalic acid, 2,2'-diphenyl-4,4'-biphenyldicarboxylic acid, 2,2'-bis(p-trifluorophenyl)-4,4'-biphenyldicarboxylic acid, 2,2'-bis(a-naphthyl)-4,4'-biphenyldicarboxylic acid, 4,4'-dicarboxydiphenyl ether, 4,4'-dicarboxy diphenyl sulfone, 5-(4-trifluoromethylphenoxy)isophthalic acid, 4,4'-carbonylbiphenyl dicarboxylic acid, 2,2-bis(4-carboxyphenyl)hexafluoropropane.

[0017] According to one preferred embodiment, the first aromatic diamine monomer is selected from one or more of: 2,5-difluoro-1,4-phenylenediamine, 2,2',6,6'-tetrafluorobiphenyl diamine, 2,2',6,6'-tetra(trifluoromethyl)stilbene diamine, 2,2'-bis(fluoro)stilbene diamine, 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), 2,2',2'',5'-tetra(trifluoromethyl)-[1,1',4',1''-terphenyl]-4,4''-diamine, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TD), N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(4-aminobenzamide) (AB-TFMB), 4,4'-diaminobenzanilide, 4,4'-diaminobenzenesulfone, p-aminophenyl p-aminobenzoate, 4,4'-((3-(trifluoromethyl)phenyl)methylene)diaminobiphenyl, 4,4'-((perfluorocyclobutane-1,2-diyl)bis(oxy))diamine, 4,4'-(1-(3,5-bis(trifluoromethyl)phenyl)-2,2,2-trifluoroethyl)diaminobiphenyl, 4,4'-((3,5-bis(trifluoromethyl)phenyl)methylene)diaminobiphenyl, 4-(4-(2-(4-(4-aminophenoxy)phenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl)phenoxy)aniline, 4-(4-(2-(4-(4-aminophenoxy)phenyl)-2-propyl)phenoxy)aniline, 3-(1-(3-aminophenyl)-2,2,2-trifluoro-1-phenylethyl)aniline, 4-(4-aminophenoxy)-3,5-bis(trifluoromethyl)aniline, bis(4-hydroxyphenyl)terephthalate, 3-(3-aminophenylsulfanyl)aniline, 3-(3-aminobenzyl)aniline, 4-(4-(4-aminophenoxy)phenoxy)aniline, 4,4'-diaminobenzenesulfone, p-aminophenyl p-aminobenzoate, 2,2'-bis(3-aminophenyl)hexafluoropropane, 4-(4-(4-aminophenoxy)-2,3,5,6-tetrafluorophenoxy)aniline.

[0018] According to a preferred embodiment, the second phenolic hydroxyl group containing aromatic diamine monomer is selected from one or more of: 4,6-diaminoresorcinol, 3,3'-diamino-4,4'-biphenyldiol, 2-amino-4-(3-amino-4-hydroxyphenoxy)phenol, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone, 2,2'-bis(4-hydroxy-3-aminophenyl)propane, 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 3-amino-N-(3-amino-4-hydroxyphenyl)-4-hydroxybenzamide, 2-amino-5-(4-(4-amino-3-hydroxyphenoxy)-2,3,5,6-tetrafluorophenoxy)phenol, 2-amino-4-(1-(3-amino-4-hydroxyphenyl)-2,2,2-trifluoro-1-phenylethyl)phenol, N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(3-hydroxy-4-aminobenzamide), 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]propane, 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane, 2,2'-bis[(3-hydroxy-4-aminophenoxy)-4-phenyl]hexafluoropropane, 2,2'-bis(trifluoromethyl)-(3-hydroxy-4-aminophenoxy)biphenyl, 2,2'-bis[(4-hydroxy-5-aminopyridin-2-yloxy)-4-phenyl]hexafluoropropane, 2-amino-5-(1-(4-amino-3-hydroxyphenyl)-1-(4-(trifluoromethyl)phenyl)ethyl)phenol.

[0019] According to a preferred embodiment, the aromatic diisocyanate is selected from one or more of: bis(4-isocyanatocyclohexyl)methane, isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, m-xylylene diisocyanate, toluene-2,6-diisocyanate (2,6-TDI), 1,3-bis(isocyanatomethyl)-2-methylbenzene, 1-isocyanato-4-[(4-isocyanatocyclohex-2,4-dienyl)methyl]benzene, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, 2-isocyanato-4-[(3-isocyanato-4-methylcyclohex-2,4-dienyl)methyl]-1-methylbenzene, 2,4-diisocyanato-1-methylbenzene, 3,5-diisocyanato-1-methylbenzene, 2,5-diisocyanato-1-methylbenzene, and p-phenylene diisocyanate.

[0020] According to a preferred embodiment, the polyamide material has a structure represented by the following Formula I: Formula I wherein the main chain structure comprises a first amide segment and a second amide segment, m is the number of repetitions of the first amide segment, n is the number of repetitions of the second amide segment, and m and n are independently a number greater than 0, m:n = (9-9.5):(1-0.5); Ar1, Ar2, Ar3, Ar4, and Ar5 are defined as described above.

[0021] According to one preferred embodiment, the polyamide material has one or more of the following properties: a glass transition temperature (Tg) higher than 300°C; a transmittance (Tt) at 550 nm of 86-92% for a film thickness of 50 μm; a tensile strength higher than 185 MPa; an elongation at break greater than 25%; a Haze lower than 1.0 for a film thickness of 50 μm; a Yellowness Index (YI) less than 2.2 for a film thickness of 50 μm; a water absorption less than 2.2%; and / or a crosslinking density less than 1.50 x 10 -4 mol / cm 3 .

[0022] According to another aspect, there is provided a method for preparing a polyamide material, comprising the steps of: mixing a first aromatic diacid monomer, a second aromatic diacid monomer, a first aromatic diamine monomer and a second aromatic diamine monomer containing phenolic hydroxyl group, a catalyst, a cosolvent and a polymerization promoter in a first organic solvent, and heating the mixture to 100-150°C to perform a polymerization reaction to obtain a linear polyamide resin slurry; precipitating and solidifying the linear polyamide resin slurry in a second organic solvent to separate a linear polyamide resin; dissolving the linear polyamide resin and an isocyanate crosslinking agent in a third organic solvent to obtain a crosslinking type polyamide resin prepolymer slurry; preforming the crosslinking type polyamide resin prepolymer slurry and heating to 100-300°C to perform crosslinking and solidification to obtain the polyamide material.

[0023] According to one preferred embodiment, the ratio of the sum of the molar amounts of the first aromatic diamine monomer and the second aromatic diamine monomer containing phenolic hydroxyl group to the sum of the molar amounts of the first aromatic diacid monomer and the second aromatic diacid monomer is 100:(99-99.9); The proportion of the second aromatic diamine monomer containing phenolic hydroxyl group is 0.5-0.7% based on the total molar amount of the first aromatic diamine monomer and the second aromatic diamine monomer containing phenolic hydroxyl group; the sum of the mass of the first aromatic diamine monomer, the second aromatic diamine monomer containing phenolic hydroxyl group, the first aromatic diacid monomer and the second aromatic diacid monomer is 10% to 20% of the mass of the first organic solvent; and / or the added amount of the isocyanate crosslinking agent is 1.2 to 1.8 times of the molar amount of the second aromatic diamine monomer containing phenolic hydroxyl group.

[0024] According to a preferred embodiment, the crosslinking and curing step comprises coating the linear polyamide resin slurry into a prepolymer film before heating the linear polyamide resin slurry, heating the prepolymer film, and performing crosslinking and curing to obtain the polyamide film material.

[0025] According to a preferred embodiment, the catalyst is selected from one or more of pyridine, 2-methylpyridine, 3-methylpyridine and triethylamine; the cosolvent is one or both of anhydrous calcium chloride and anhydrous lithium chloride; the polymerization promoter is one or both of triphenyl phosphite and dimethyl sulfoxide; the first organic solvent and the third organic solvent are each independently selected from one or more of N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide and cyclopentanone (preferably N-methylpyrrolidone); and / or the second organic solvent is a lower aliphatic alcohol, preferably ethanol. According to a preferred embodiment, the linear polyamide resin obtained by separation is washed with the second organic solvent for 2 to 3 times, and the washed linear polyamide resin is vacuum dried at a temperature of 160 to 180°C for 6 to 10 hours to obtain the dried linear polyamide resin.

[0026] According to a preferred embodiment, the heating of the prepolymer film comprises vacuum drying at 80°C for 2 hours, and then sequentially holding at constant temperatures of 100°C, 150°C, 200°C, 260°C and 300°C for 30 minutes respectively.

[0027] According to yet another aspect, there is provided a polyamide film made of the above polyamide material.

[0028] According to still another aspect, there is provided an application of the above polyamide material or the above polyamide film as a substrate for making a flexible printed circuit board.

[0029] There is provided an application of the above polyamide material as a substrate for making a flexible printed circuit board.

[0030] Compared with existing technologies, this invention improves the transparency of polymer materials by designing the polymer molecular chain segment structure and introducing benzene ring-containing structural units into the main chain to disrupt the regular arrangement of the molecular chains, thereby reducing or eliminating the crystallinity of the polymer material. Furthermore, by adjusting the amount of phenolic hydroxyl-containing aromatic diamine monomers and the proportion of crosslinking agents in the polyamide synthesis raw materials, it achieves synergistic control over the thermodynamic properties and transparency of the material. The technical solution of this invention not only improves the mechanical properties and heat resistance of the material but also maintains excellent optical clarity. Attached Figure Description

[0031] Figures 1 to 5 The infrared spectra of the polyamide films prepared according to Examples 1 to 5 are shown respectively. Detailed Implementation

[0032] The present invention will be further illustrated below through specific embodiments, but the present invention is not limited thereto.

[0033] Polyamide materials The polyamide material according to the present invention comprises a main chain structure and a connecting structure. The main chain structure comprises a first aromatic diacid monomer. The first structural unit formed is composed of the second aromatic diacid monomer. The second structural unit formed is composed of the first aromatic diamine monomer. The third structural unit formed and the second aromatic diamine monomer containing a phenolic hydroxyl group The fourth structural unit is formed. Furthermore, the first, second, third, and fourth structural units are connected in a random aggregation manner.

[0034] According to one specific embodiment, the main chain structure has a first amide segment and a second amide segment. The first amide segment is composed of a first aromatic diacid monomer. Second aromatic diacid monomer and the first aromatic diamine monomer Polymerization forms the second amide segment, which is formed from the first aromatic diacid monomer. Second aromatic diacid monomer and second aromatic diamine monomers containing phenolic hydroxyl groups Formed by polymerization.

[0035] The first and second aromatic diacid monomers can be the same or different. Therefore, Ar1 and Ar5 can be the same or different, and each is independently composed of monomers selected from phenylene, -O-, biphenylene, -C(=O)-, C... 1-4 One or more groups from alkylene and sulfone groups are linked together to form the phenylene, biphenylene, and C 1-4 The alkylene group may optionally be substituted with one or more of the following substituents: C1-4 Alkyl (preferably methyl, tert-butyl), halogenated C 1-4 Alkyl (preferably trifluoromethyl), halogen (preferably -Cl), substituted or unsubstituted phenyl and substituted or unsubstituted naphthyl, wherein the phenyl and naphthyl are optionally selected from C. 1-4 Alkyl (preferably methyl, tert-butyl), halogenated C 1-4 One or more substituents of alkyl (preferably trifluoromethyl) and halogen (preferably -Cl) are used for substitution.

[0036] According to one embodiment, Ar1 and Ar5 can be substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene, a combination of one or more optionally substituted phenylene with -O-, a combination of one or more optionally substituted phenylene with -C(=O)-, or a combination of one or more optionally substituted phenylene with optional substituted C-. 1-4 Combinations of alkylene groups, or combinations of one or more optionally substituted phenylene groups and sulfone groups. Wherein, phenylene, biphenylene, C 1-4 The alkylene group is optionally substituted with one or more substituents selected from methyl, tert-butyl, trifluoromethyl, -Cl, phenoxy, phenyl, or naphthyl. Here, the phenoxy, phenyl, and naphthyl substituents may be further substituted with trifluoromethyl.

[0037] More preferably, Ar1 and Ar5 can be independently selected from one or more of the following structures: .

[0039] According to a specific embodiment, the first aromatic diacid monomer and the second aromatic diacid monomer are independently selected from one or more of the following: terephthalic acid, 4,4'-biphenyldicarboxylic acid, 2-methyl-4,4'-biphenyldicarboxylic acid, 2,5-dichloroterephthalic acid, 2,2'-biphenyldicarboxylic acid, 2-trifluoromethylterephthalic acid, 2-methylterephthalic acid, isophthalic acid, 2,2'-di(trifluoromethyl)-4,4'-biphenyldicarboxylic acid, 2-trifluoromethyl-4,4'-biphenyldicarboxylic acid, 2-tert-butylisophthalic acid, 2,2'-diphenyl-4,4'-biphenyldicarboxylic acid. Phthalic acid, 2,2'-bis(p-trifluorophenyl)-4,4'-biphenyl dicarboxylic acid, 2,2'-bis(α-naphthyl)-4,4'-biphenyl dicarboxylic acid, 4,4'-dicarboxylic diphenyl ether, 4,4'-dicarboxylic diphenyl sulfone, 5-(4-trifluoromethylphenoxy)isophthalic acid, 4,4'-carbonyldibenzoic acid, 2,2-bis(4-carboxyphenyl)hexafluoropropane; preferably isophthalic acid, 2-methyl-4,4'-biphenyl dicarboxylic acid, 2,2'-bis(p-trifluorophenyl)-4,4'-biphenyl dicarboxylic acid and 5-(4-trifluoromethylphenoxy)isophthalic acid.

[0040] According to another embodiment, Ar2in the first aromatic diamine monomer can be formed by linking one or more groups selected from phenylene, -0-, biphenylene, -NH-, -C(=0)-, -S-, C 1-4 alkylene, C 3-4 cycloalkylene, and sulfone. And, wherein the phenylene, biphenylene, C 1-4 alkylene, and C 3-4 cycloalkylene are optionally substituted with one or more substituents selected from C 1-4 alkyl (preferably methyl, t-butyl), haloC 1-4 alkyl (preferably trifluoromethyl), halo (preferably -F), substituted or unsubstituted fluorenyl, and substituted or unsubstituted phenyl. Here, the phenyl and fluorenyl as substituents are optionally further substituted with one or more substituents selected from C 1-4 alkyl (preferably methyl), haloC 1-4 alkyl (preferably trifluoromethyl), and halo (preferably -F).

[0041] According to one specific embodiment, Ar2may be substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene, a combination of one or more optionally substituted phenylene and amido, a combination of one or more optionally substituted phenylene and -C(=0)0-, a combination of one or more optionally substituted phenylene and -0-, a combination of one or more optionally substituted phenylene and -S-, a combination of one or more optionally substituted phenylene and -0- and optionally substituted C 1-4 alkylene, a combination of one or more optionally substituted phenylene and -0- and optionally substituted C 3-4 cycloalkylene, a combination of one or more optionally substituted phenylene and optionally substituted C 1-4 alkylene, or a combination of one or more optionally substituted phenylene and sulfone. Here, the phenylene, biphenylene, C 1-4 alkylene, and C 3-4 cycloalkylene are optionally substituted with one or more substituents selected from methyl, t-butyl, trifluoromethyl, -F, fluorenyl, or phenyl. Here, the phenyl and fluorenyl as substituents are optionally further substituted with trifluoromethyl.

[0042] Preferably, the first aromatic diamine monomer described above can be selected from one or more of 2,5-difluoro-1,4-phenylenediamine, 2,2',6,6'-tetrafluorobiphenyl diamine, 2,2',6,6'-tetra(trifluoromethyl)stilbene diamine, 2,2'-bis(fluoro)stilbene diamine; 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), 2,2',2'',5'-tetra(trifluoromethyl)-[1,1',4',1''-terphenyl]-4,4''-diamine, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TD), N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(4-aminobenzamide) (AB-TFMB); 4,4'-diaminobenzanilide, 4,4'-diaminobenzenesulfone, p-aminophenyl p-aminophenyl ester benzoate, 4,4'-((3-(trifluoromethyl)phenyl)methylene)diphenyl diamine, 4,4'-((perfluorocyclobutane-1,2-diyl)bis(oxy))diamine, 4,4'-(1-(3,5-bis(trifluoromethyl)phenyl)-2,2,2-trifluoroethyl)diphenyl diamine, 4,4'-((3,5-bis(trifluoromethyl)phenyl)methylene)diphenyl diamine, 4-(4-(2-(4-(4-aminophenoxy)phenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl)phenoxy)aniline, 4-(4-(2-(4-(4-aminophenoxy)phenyl)-2-propyl)phenoxy)aniline, 3-(1-(3-aminophenyl)-2,2,2-trifluoro-1-phenylethyl)aniline, 4-(4-aminophenoxy)-3,5-bis(trifluoromethyl)aniline, bis(4-hydroxyphenyl)terephthalate, 3-(3-aminophenylthio)aniline, 3-(3-aminobenzyl)aniline, 4-(4-(4-aminophenoxy)phenoxy)aniline, 4,4'-diaminobenzenesulfone, p-aminophenyl p-aminophenyl ester benzoate, 2,2'-bis(3-aminophenyl)hexafluoropropane, 4-(4-(4-aminophenoxy)-2,3,5,6-tetrafluorophenoxy)aniline; preferably 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 4-(4-(2-(4-(4-aminophenoxy)phenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl)phenoxy)aniline, or N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(4-aminobenzamide).

[0043] Ar3in the second aromatic diamine monomer described above containing a phenolic hydroxyl group is derived from a tetrasubstituted phenylene, -O-, a tetrasubstituted biphenylene, a disubstituted phenylene, -NH-, -C(=O)-, C 1-4one or more of the groups alkylene, sulfone and pyridinylene is linked to form. Also, tetra-substituted phenylene, tetra-substituted biphenylene, di-substituted phenylene and C 1-4 alkylene is optionally substituted with one or more substituents selected from the group consisting of C 1-4 alkyl (preferably methyl), halo-C 1-4 alkyl (preferably trifluoromethyl), halo (preferably -F) and substituted or unsubstituted phenyl. The phenyl as a substituent here is optionally substituted with one or more substituents selected from the group consisting of C 1-4 alkyl (preferably methyl, tert-butyl), halo-C 1-4 alkyl (preferably trifluoromethyl) and halo (preferably -F).

[0044] According to one specific embodiment, Ar3may be one or more of the following structures: .

[0046] According to one preferred embodiment, the above-mentioned second aromatic diamine monomer containing phenolic hydroxyl groups is selected from one or more of the following: 4,6-diaminoresorcinol, 3,3'-diamino-4,4'-biphenyldiol, 2-amino-4-(3-amino-4-hydroxyphenoxy)phenol, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone, 2,2'-bis(4-hydroxy-3-aminophenyl)propane, 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 3-amino-N-(3-amino-4-hydroxyphenyl)-4-hydroxybenzamide, 2-amino-5-(4-(4-amino-3-hydroxyphenoxy)-2,3,5,6-tetrafluorophenoxy)phenol, 2-amino-4-(1-(3-amino-4-hydroxyphenyl)-2,2,2-trifluoro-1-phenylethyl)phenol, N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(3-hydroxy-4-aminobenzamide), 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]propane, 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane, 2,2'-bis[(3-hydroxy-4-aminophenoxy)-4-phenyl]hexafluoropropane, 2,2'-bis(trifluoromethyl)-(3-hydroxy-4-aminophenoxy)biphenyl, 2,2'-bis[(4-hydroxy-5-aminopyridin-2-yloxy)-4-phenyl]hexafluoropropane, 2-amino-5-(1-(4-amino-3-hydroxyphenyl)-1-(4-(trifluoromethyl)phenyl)ethyl)phenol, preferably 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane.

[0047] According to yet another embodiment, the linking structure is formed by a polymeric reaction of an aromatic diisocyanate with the phenolic hydroxyl groups of the second amide segment, such that the backbone structures are crosslinked to one another. Specifically, the linking structure is formed by represented by Formula II.

[0048] wherein Ar4is formed by one or more groups selected from phenylene, naphthylene, C 1-4 alkylene, and C 3-6 cycloalkylene, wherein phenylene, naphthylene, C 1-4 alkylene, and C 3-6 cycloalkylene are optionally substituted with one or more substituents selected from C 1-4 alkyl (preferably methyl), haloC 1-4 alkyl (preferably trifluoromethyl), and halo (preferably -F).

[0049] Ar4is selected from one or more of the following structures: -C x H 2x - wherein x is an integer from 1 to 6, such as 2, 3, 4, or 5;

[0050] .

[0052] According to one specific embodiment, the aromatic diisocyanate is selected from one or more of the following: bis(4-isocyanatocyclohexyl)methane, isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, m-xylylene diisocyanate, toluene-2,6-diisocyanate (2,6-TDI), 1,3-bis(isocyanatomethyl)-2-methylbenzene, 1 -isocyanato-4-[(4-isocyanatocyclohex-2,4-dienyl)methyl]benzene, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, 2-isocyanato-4-[(3-isocyanato-4-methylcyclohex-2,4-dienyl)methyl]-1 -methylbenzene, 2,4-diisocyanato-1 -methylbenzene, 3,5-diisocyanato-1 -methylbenzene, 2,5-diisocyanato-1 -methylbenzene, and p-phenylene diisocyanate, preferably 1,3-bis(isocyanatomethyl)-2-methylbenzene.

[0053] According to one preferred embodiment, the polyamide material has a structure represented by Formula I:

[0054] Formula I wherein m is the number of repetitions of the first amide segment, n is the number of repetitions of the second amide segment, and m and n are independently a number greater than 0, m:n = (9-9.5):(1-0.5).

[0055] Ar1, Ar2, Ar3, Ar4and Ar5are defined as described above.

[0056] In the polyamide material of the present application, benzene ring structures are introduced into the main chain structure of the polyamide material by the first aromatic diacid, the second aromatic diacid, the first aromatic diamine and the second aromatic diamine containing phenolic hydroxyl groups, and the first amide segment formed by the first aromatic diamine accounts for the major part of the benzene ring-containing part in the main chain structure, thereby disrupting the regular arrangement of the main chain structure, reducing the crystallinity of the polymer, and even making the polymer non-crystalline, and thus improving the transparency of the polymer material.

[0057] On the other hand, the second amide segment formed by the second aromatic diamine introduces phenolic hydroxyl groups into the main chain structure of the polyamide material, thereby providing active sites for the crosslinking of the main chain structures with each other by the crosslinking agent. By adjusting the content of the phenolic hydroxyl groups in the main chain structure and the addition ratio of the crosslinking agent, the thermodynamic properties and the transparency of the polymer material can be synergistically controlled.

[0058] On the other hand, the second amide segment formed by the second aromatic diamine introduces phenolic hydroxyl groups into the main chain structure of the polyamide material, thereby providing active sites for the crosslinking of the main chain structures with each other by the crosslinking agent. By adjusting the content of the phenolic hydroxyl groups in the main chain structure and the addition ratio of the crosslinking agent, the thermodynamic properties and the transparency of the polymer material can be synergistically controlled.

[0059] Specifically, the polyamide material of the present application can achieve one or more of the following properties, and preferably has all of the following properties, at a thickness of 50 ± 1 μm (determined according to ASTM D374): a glass transition temperature (Tg) higher than 300°C, preferably above 302°C, further preferably above 308°C, for example 310°C, 312°C, 314°C, 316°C, 318°C, 320°C, 324°C or 327°C, determined according to ASTM D3418; a transmittance (Tt) at 550 nm of 86% to 92%, for example 87%, 88% or 89%, determined according to ASTM E313, when the film thickness of the polyamide material is 50 μm; a tensile strength higher than 185 MPa, preferably above 210 MPa, for example 221 MPa or 228 MPa, determined according to ASTM D882; an elongation at break greater than 25%, preferably above 26%, further preferably from 30% to 45%, for example 32%, 35%, 38%, 40% or 43%, determined according to ASTM D882; The polyamide material has a haze (Haze) of less than 1.0%, preferably 0.8% or less, for example 0.7%, 0.6%, 0.5%, 0.4% or 0.3%, when the film thickness is 50 pm, as determined according to ASTM E313; The polyamide material has a yellow index (YI) of less than 2.2, preferably 1.9% or less, for example 1.8, 1.7, 1.6, 1.5, 1.4 or 1.3, when the film thickness is 50 pm, as determined according to ASTM E313; The polyamide material has a water absorption of less than 2.2%, preferably 1.9% or less, for example 1.8%, 1.7%, 1.6%, 1.5%, 1.4% or 1.3%, as determined according to ASTM D570; and / or The polyamide material has a crosslinking density of less than 1.50 x 10 -4 mol / cm 3 , preferably 1.35 x 10 -4 mol / cm 3 or less, for example 1.30 x 10 -4 mol / cm 3 , 1.25 x 10 -4 mol / cm 3 , 1.20 x 10 -4 mol / cm 3 , 1.15 x 10 -4 mol / cm 3 , 1.10 x 10 -4 mol / cm 3 , 1.05 x 10 -4 mol / cm 3 , 1.00 x 10 -4 mol / cm 3 , 0.85 x 10 -4 mol / cm 3 , 0.75 x 10 -4 mol / cm 3 or 0.65 x 10 -4 mol / cm 3 , as determined according to ASTM D2765.

[0060] Therefore, the polyamide material according to the present application maintains excellent optical transparency, especially balanced transmittance, yellowness index and haze, while also having excellent solubility, thermodynamic properties and thermal stability, such as tensile strength, elongation at break, and has a suitable glass transition temperature and water absorption. This new type of transparent material provides technical support for optimizing transparent electronic devices, can be applied to flexible printed circuit boards, and has a broad application prospect in the fields of transparent display screens, touch devices, vehicle screens, health sensors, smart windows, etc., especially in the consumer electronics, unmanned aerial vehicles, new energy vehicles, intelligent robots and new energy vehicle industries.

[0061] Method for preparing polyamide material Another aspect of the present application provides a method for preparing a polyamide material, comprising a main chain structure polymerization step, a separation post-treatment step and a cross-linking step.

[0062] The main chain structure polymerization step comprises mixing a first aromatic diacid monomer, a second aromatic diacid monomer, a first aromatic diamine monomer and a second aromatic diamine monomer containing phenolic hydroxyl, a catalyst, a cosolvent and a polymerization promoter in a first organic solvent, and heating the mixture to 100-150°C to carry out a polymerization reaction to obtain a linear polyamide resin slurry.

[0063] Preferably, the mixing step in the main chain structure polymerization step is carried out at room temperature in an inert atmosphere, preferably under stirring. The polymerization reaction is carried out at a temperature of 100-150°C, preferably 110-140°C, for example 115°C, 120°C, 125°C, 130°C or 135°C, for example for 8-12 hours, for example 9 hours, 10 hours or 11 hours.

[0064] Preferably, the ratio of the sum of the molar amounts of the first aromatic diamine monomer and the second aromatic diamine monomer containing phenolic hydroxyl to the sum of the molar amounts of the first aromatic diacid monomer and the second aromatic diacid monomer is 100:(99-99.9).

[0065] Preferably, the proportion of the second aromatic diamine monomer containing phenolic hydroxyl is 0.5%-0.7%, for example 0.6%, based on the total molar amount of the first aromatic diamine monomer and the second aromatic diamine monomer containing phenolic hydroxyl.

[0066] Further, the sum of the masses of the first aromatic diamine monomer, the second aromatic diamine monomer containing phenolic hydroxyl, the first aromatic diacid monomer and the second aromatic diacid monomer is 10%-20%, preferably 13%-18%, for example 14%, 15%, 16% or 17%, of the mass of the first organic solvent.

[0067] According to one embodiment, the method according to the present application can be carried out by the process represented by the following schematic formula III:

[0068] Formula III.

[0069] According to one specific embodiment, in the main chain structure polymerization step, the first aromatic diacid monomer, the second aromatic diacid monomer, the first aromatic diamine monomer and the second aromatic diamine monomer containing phenolic hydroxyl group are subjected to random polymerization reaction together in the presence of a catalyst, a cosolvent and a polymerization promoter.

[0070] The separation post-treatment step can include precipitating and solidifying the linear polyamide resin slurry obtained in the polymerization step in a second organic solvent, and separating the linear polyamide resin. Specifically, the linear polyamide resin is precipitated from the second organic solvent, subjected to solid-liquid separation, and the separated solid is washed with the second organic solvent for 2 to 3 times, and then the washed linear polyamide resin is vacuum dried at 160 to 180°C for 6 to 10 hours to obtain a cross-linked polyamide resin prepolymer.

[0071] The cross-linking step can include dissolving the cross-linked polyamide resin prepolymer obtained in the separation post-treatment step and the isocyanate cross-linking agent in a third organic solvent to obtain a cross-linked polyamide resin prepolymer slurry; and preforming the cross-linked polyamide resin prepolymer slurry and heating to 100 to 300°C to perform cross-linking and solidification to obtain a polyamide material, such as a micro-cross-linked polyamide film material. The preforming is, for example, coating the cross-linked polyamide resin prepolymer slurry on a glass substrate to form a liquid film.

[0072] The cross-linking and solidification step includes, before heating the cross-linked polyamide resin prepolymer slurry, coating the cross-linked polyamide resin prepolymer slurry into a prepolymer film, heating the prepolymer film to perform cross-linking and solidification to obtain a polyamide film material. Preferably, the prepolymer film obtained by coating is heated first at 80°C for 2 hours under vacuum, and then heated to 100°C, 150°C, 200°C, 260°C and 300°C in sequence, and kept at each temperature for 30 minutes, so that the prepolymer film is completely cross-linked and solidified, and finally a polyamide film material is obtained, wherein the temperature increasing rate between each temperature zone is 10°C / min. The obtained polyamide film material is cooled to room temperature, so that it can be peeled off.

[0073] The molar addition amount of the isocyanate cross-linking agent is 1.2 to 1.8 times, for example, 1.3 times, 1.4 times, 1.5 times, 1.6 times or 1.7 times, of the molar amount of the second aromatic diamine monomer containing phenolic hydroxyl group.

[0074] According to one specific embodiment, the method according to the present application comprises: under stirring at room temperature in an inert atmosphere, adding into a container equipped with stirring device, the first organic solvent, the first aromatic diamine monomer and the second aromatic diamine monomer containing phenolic hydroxyl group, the first aromatic diacid monomer, the second aromatic diacid monomer (the two diacid monomers are weighed separately and mixed uniformly before being added slowly at one time), anhydrous calcium chloride, triphenyl phosphite and pyridine, after being fully stirred and dissolved, heating at 100-150°C for 8-12 hours to obtain a homogeneous colorless transparent linear polyamide solution. The linear polyamide solution is precipitated and solidified in the second organic solvent, after solid-liquid separation, the solid resin is washed with the second organic solvent for 2-3 times, and then the resin is vacuum dried at 16-180°C for 6-10 hours. The obtained linear polyamide resin and diisocyanate crosslinking agent are dissolved in the third organic solvent, and fully stirred to obtain a transparent crosslinking type polyamide resin prepolymer slurry with good fluidity. Finally, the crosslinking type polyamide resin prepolymer slurry is coated into a film and subjected to thermal crosslinking reaction, thereby obtaining a colorless transparent high-temperature-resistant polyamide film.

[0075] According to one specific embodiment, the first aromatic diacid monomer and the second aromatic diacid monomer described above can be the same or different, and each is independently selected from one or more of the following: terephthalic acid, 4,4'-biphenyldicarboxylic acid, 2-methyl-4,4'-biphenyldicarboxylic acid, 2,5-dichloroterephthalic acid, 2,2'-biphenyldicarboxylic acid, 2-trifluoromethylterephthalic acid, 2-methylterephthalic acid, isophthalic acid, 2,2'-bis(trifluoromethyl)-4,4'-biphenyldicarboxylic acid, 2-trifluoromethyl-4,4'-biphenyldicarboxylic acid, 2-tert-butylisophthalic acid, 2,2'-diphenyl-4,4'-biphenyldicarboxylic acid, 2,2'-bis(p-trifluorophenyl)-4,4'-biphenyldicarboxylic acid, 2,2'-bis(α-naphthyl)-4,4'-biphenyldicarboxylic acid, 4,4'-dicarboxy diphenyl ether, 4,4'-dicarboxy diphenyl sulfone, 5-(4-trifluoromethylphenoxy)isophthalic acid, 4,4'-carbonylbiphenyl dicarboxylic acid, 2,2-bis(4-carboxyphenyl)hexafluoropropane; preferably isophthalic acid, 2-methyl-4,4'-biphenyldicarboxylic acid, 2,2'-bis(p-trifluorophenyl)-4,4'-biphenyldicarboxylic acid and 5-(4-trifluoromethylphenoxy)isophthalic acid.

[0076] The first aromatic diamine monomer can be selected from one or more of 2,5-difluoro-1,4-phenylenediamine, 2,2',6,6'-tetrafluorobiphenyl diamine, 2,2',6,6'-tetra(trifluoromethyl)stilbene diamine, 2,2'-bis(fluoro)stilbene diamine; 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), 2,2',2'',5'-tetra(trifluoromethyl)-[1,1',4',1''-biphenyl]-4,4''-diamine, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TD), N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(4-aminobenzamide) (AB-TFMB); 4,4'-diaminobenzanilide, 4,4'-diaminobenzenesulfone, p-aminophenyl p-aminobenzoate, 4,4'-((3-(trifluoromethyl)phenyl)methylene)diphenyl diamine, 4,4'-((perfluorocyclobutane-1,2-diyl)bis(oxy))diamine, 4,4'-(1-(3,5-bis(trifluoromethyl)phenyl)-2,2,2-trifluoroethyl)diphenyl diamine, 4,4'-((3,5-bis(trifluoromethyl)phenyl)methylene)diphenyl diamine, 4-(4-(2-(4-(4-aminophenoxy)phenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl)phenoxy)aniline, 4-(4-(2-(4-(4-aminophenoxy)phenyl)-2-propyl)phenoxy)aniline, 3-(1-(3-aminophenyl)-2,2,2-trifluoro-1-phenylethyl)aniline, 4-(4-aminophenoxy)-3,5-bis(trifluoromethyl)aniline, bis(4-hydroxyphenyl)terephthalate, 3-(3-aminophenylsulfanyl)aniline, 3-(3-aminobenzyl)aniline, 4-(4-(4-aminophenoxy)phenoxy)aniline, 4,4'-diaminobenzenesulfone, p-aminophenyl p-aminobenzoate, 2,2'-bis(3-aminophenyl)hexafluoropropane, 4-(4-(4-aminophenoxy)-2,3,5,6-tetrafluorophenoxy)aniline; preferably 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 4-(4-(2-(4-(4-aminophenoxy)phenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl)phenoxy)aniline, or N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(4-aminobenzamide).

[0077] The second aromatic diamine monomer having a phenolic hydroxyl group described above is selected from one or more of 4,6-diaminoresorcinol, 3,3'-diamino-4,4'-biphenyldiol, 2-amino-4-(3-amino-4-hydroxyphenoxy)phenol, 3,3'-diamino-4,4'-dihydroxydiphenylsulfone, 2,2'-bis(4-hydroxy-3-aminophenyl)propane, 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 3-amino-N-(3-amino-4-hydroxyphenyl)-4-hydroxybenzamide, 2-amino-5-(4-(4-amino-3-hydroxyphenoxy)-2,3,5,6-tetrafluorophenoxy)phenol, 2-amino-4-(1-(3-amino-4-hydroxyphenyl)-2,2,2-trifluoro-1-phenylethyl)phenol, N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(3-hydroxy-4-aminobenzamide), 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]propane, 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane, 2,2'-bis[(3-hydroxy-4-aminophenoxy)-4-phenyl]hexafluoropropane, 2,2'-bis(trifluoromethyl)-(3-hydroxy-4-aminophenoxy)biphenyl, 2,2'-bis[(4-hydroxy-5-aminopyridin-2-yloxy)-4-phenyl]hexafluoropropane, 2-amino-5-(1-(4-amino-3-hydroxyphenyl)-1-(4-(trifluoromethyl)phenyl)ethyl)phenol, preferably 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane.

[0078] The isocyanate crosslinking agent described above can be an aromatic diisocyanate, for example, selected from one or more of bis(4-isocyanatocyclohexyl)methane, isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, m-xylylene diisocyanate, toluene-2,6-diisocyanate (2,6-TDI), 1,3-bis(methyl isocyanato)-2-methylbenzene, 1-isocyanato-4-[(4-isocyanatocyclohex-2,4-dienyl)methyl]benzene, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, 2-isocyanato-4-[(3-isocyanato-4-methylcyclohex-2,4-dienyl)methyl]-1-methylbenzene, 2,4-diisocyanato-1-methylbenzene, 3,5-diisocyanato-1-methylbenzene, 2,5-diisocyanato-1-methylbenzene, and p-phenylene diisocyanate, preferably 1,3-bis(methyl isocyanato)-2-methylbenzene.

[0079] The first and third organic solvents described above can be the same or different and are each independently selected from one or more of N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and cyclopentanone, preferably N-methylpyrrolidone.

[0080] The second organic solvent can be a lower aliphatic alcohol, preferably a C 1-4 aliphatic alcohol, more preferably ethanol.

[0081] The catalyst used in the method of the present application for polymerization of the diacid and diamine compounds can be pyridine, the cosolvent can be anhydrous calcium chloride, and / or the polymerization promoter can be triphenyl phosphite.

[0082] According to one specific embodiment, the method according to the present application comprises: under stirring in an inert atmosphere at room temperature, adding N-methyl pyrrolidone, a first aromatic diamine monomer and a second aromatic diamine monomer containing phenolic hydroxyl group, an aromatic diacid monomer, anhydrous calcium chloride, triphenyl phosphite and pyridine into a three-neck flask equipped with a mechanical stirring device, dissolving thoroughly under stirring and heating at 100-150°C for 8-12 hours to obtain a homogeneous colorless transparent polyamide solution. The polyamide solution is precipitated and solidified in an ethanol system, and after solid-liquid separation, the solid polyamide resin is washed with ethanol for 2-3 times, and then the polyamide resin is vacuum dried at 160-180°C for 6-10 hours. The obtained polyamide resin and diisocyanate crosslinking agent are dissolved in N-methyl pyrrolidone, and after thorough stirring, a good flowability and transparent polyamide slurry is obtained. Finally, the slurry is made into a film, and a thermal crosslinking reaction is carried out, thereby obtaining a colorless transparent high-temperature resistant polyamide film.

[0083] Application of the polyamide material According to another aspect of the present application, a polyamide film made of the above polyamide material or prepared by the above method is provided. The polyamide film is colorless and transparent and can resist high temperature.

[0084] According to still another aspect of the present application, the above polyamide material or polyamide film is also provided for use as a substrate for making a flexible printed circuit board.

[0085] In order to make the technical solutions and advantages of the present application clearer, the present application will be further described in detail below in combination with embodiments, and the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Other embodiments obtained without creative work are all within the protection scope of the present application.

[0086] Example 1: The preparation steps of the colorless transparent high-temperature resistant polyamide film are as follows: S1: Into a 250 mL three-necked flask equipped with a mechanical stirring device, 134.70 g of N-methylpyrrolidone, 14.4104 g (45 mmol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 0.1367 g (0.23 mmol) of 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane, 3.7567 g (22.61 mmol) of isophthalic acid, 5.4666 g (22.57 mmol) of 2-methylbiphenyl dicarboxylic acid, 6.80 g of anhydrous calcium chloride, 0.04 g of triphenyl phosphite, 3.57 g of pyridine were added under stirring, and the solution was heated at 100-150 °C for 8-12 hours to obtain a homogeneous colorless polyamide solution.

[0087] S2: The colorless polymer slurry was precipitated and solidified in an ethanol system, and the solid resin was washed with ethanol for 2-3 times after solid-liquid separation, and then the resin was dried at 160-180 °C under vacuum for 6-10 hours to obtain a white polyamide resin.

[0088] S3: Into a 250 mL three-necked flask, 85 g of N-methylpyrrolidone and 0.0465 g (1.5 times) of 1,3-bis(isocyanate methyl)-2-methylbenzene were added, and 15 g of the white polyamide resin obtained in step S2 was dissolved by stirring for 4-6 hours to obtain a transparent polyamide solution with good flowability.

[0089] S4: The colorless polyamide acid solution obtained in step S3 was subjected to pressure filtration, impurity removal, defoaming, and then uniformly coated on a clean glass substrate using a doctor blade, dried at 80 °C under vacuum for 2 h, and then placed in a forced air drying oven, and subjected to thermal crosslinking and solidification treatment at 100 °C, 150 °C, 200 °C, 260 °C and 300 °C for 30 min at each temperature, and the temperature rising rate was set at 10 °C / min in each temperature range. The CPPA film was peeled off after cooling to room temperature.

[0090] The CPPA film obtained was subjected to infrared spectrum detection, and the obtained spectrum is shown in Figure 1 .

[0091] Example 2: The preparation steps of the colorless transparent high-temperature resistant polyamide film are as follows: S1: Into a 250 mL three-necked flask equipped with a mechanical stirring device, 133.62 g of N-methylpyrrolidone, 11.2081 g (35 mmol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 0.1277 g (0.21 mmol) of 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane, 2.9248 g (17.61 mmol) of isophthalic acid, 9.3195 g (17.57 mmol) of 2,2'-bis(p-trifluorophenyl)-4,4'-biphenyldicarboxylic acid, 8.69 g of anhydrous calcium chloride, 0.05 g of triphenyl phosphite, 2.78 g of pyridine were added, and after being fully stirred and dissolved, the reaction was heated at 100-150 °C for 8-12 hours to obtain a homogeneous colorless polyamide solution.

[0092] S2: The colorless polymer slurry was precipitated and solidified in an ethanol system, and after solid-liquid separation, the solid resin was washed with ethanol for 2-3 times, and then the resin was vacuum dried at 160-180 °C for 6-10 hours to obtain a white polyamide resin.

[0093] S3: Into a 250 mL three-necked flask, 85 g of N-methylpyrrolidone and 0.0431 g (1.5 times) of 1,3-bis(isocyanate methyl)-2-methylbenzene were added, and 15 g of the white polyamide resin obtained in step S2 was stirred and dissolved for 4-6 h to obtain a transparent polyamide solution with good flowability.

[0094] S4: The colorless polyamide acid solution obtained in step S3 was subjected to pressure filtration, impurity removal, defoaming, and then uniformly coated on a clean glass substrate using a doctor blade, vacuum dried at 80 °C for 2 h, and then placed in a forced air drying oven, and subjected to thermal crosslinking and solidification treatment at 100 °C, 150 °C, 200 °C, 260 °C and 300 °C for 30 min at each temperature, and the temperature rising rate was set at 10 °C / min in each temperature zone. After cooling to room temperature, the CPPA film was peeled off.

[0095] The CPPA film obtained was subjected to infrared spectrum detection, and the obtained spectrum is shown in Figure 2 .

[0096] Example 3: The preparation steps of the colorless transparent high-temperature resistant polyamide film are as follows: S1: Into a 250 mL three-necked flask equipped with a mechanical stirring device, 145.32 g of N-methylpyrrolidone, 10.8878 g (34 mmol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 0.1241 g (0.21 mmol) of 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane, 5.5792 g (17.10 mmol) of 5-(4-(trifluoromethyl)phenoxy)isophthalic acid, 9.0533 g (17.07 mmol) of 2,2'-bis(p-trifluorophenyl)-4,4'-biphenyldicarboxylic acid, 9.45 g of anhydrous calcium chloride, 0.05 g of triphenyl phosphite, 2.70 g of pyridine were added under stirring, and the solution was heated at 100-150 °C for 8-12 hours to obtain a homogeneous colorless polyamide solution.

[0097] S2: The colorless polymer slurry was precipitated and solidified in an ethanol system, and the solid resin was washed with ethanol for 2-3 times after solid-liquid separation, and then the resin was dried at 160-180 °C under vacuum for 6-10 hours to obtain a white polyamide resin.

[0098] S3: 85 g of N-methylpyrrolidone and 0.0383 g (1.5 times) of 1,3-bis(isocyanate methyl)-2-methylbenzene were added into a 250 mL three-necked flask, and 15 g of the white polyamide resin obtained in step S2 was stirred and dissolved for 4-6 h to obtain a transparent polyamide solution with good flowability.

[0099] S4: The colorless polyamide acid solution obtained in step S3 was subjected to pressure filtration, impurity removal, and defoaming, and then uniformly coated on a clean glass substrate using a doctor blade, dried at 80 °C under vacuum for 2 h, and then placed in a forced air drying oven, and subjected to thermal crosslinking and solidification treatment at 100 °C, 150 °C, 200 °C, 260 °C, and 300 °C for 30 min at each temperature, and the temperature rising rate was set at 10 °C / min in each temperature range. The CPPA film was peeled off after cooling to room temperature.

[0100] The CPPA film obtained was subjected to infrared spectrum detection, and the obtained spectrum is shown in Figure 3 .

[0101] Example 4: The preparation steps of the colorless transparent high-temperature-resistant polyamide film are as follows: S1: Into a 250 mL three-necked flask equipped with a mechanical stirring device, 148.39 g of N-methylpyrrolidone, 15.5535 g (30 mmol) of 4-(4-(2-(4-(4-aminophenoxy)-1,1,1,3,3,3-hexafluoropropan-2-yl)phenoxy)phenylamino, 0.1278 g (0.21 mmol) of 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane, 2.5095 g (15.11 mmol) of isophthalic acid, 7.9962 g (15.08 mmol) of 2,2'-bis(p-trifluorophenyl)-4,4'-biphenyldicarboxylic acid, 8.90 g of anhydrous calcium chloride, 0.05 g of triphenyl phosphite, 2.39 g of pyridine were added under stirring, and the solution was heated at 100-150 °C for 8-12 hours to obtain a homogeneous colorless polyamide solution.

[0102] S2: The colorless polymer slurry was precipitated and solidified in an ethanol system, and the solid resin was washed with ethanol for 2-3 times after solid-liquid separation, and then the resin was dried at 160-180 °C under vacuum for 6-10 hours to obtain a white polyamide resin.

[0103] S3: 85 g of N-methylpyrrolidone and 0.0409 g (1.6 times) of 1,3-bis(isocyanate methyl)-2-methylbenzene were added to a 250 mL three-necked flask, and 15 g of the white polyamide resin obtained in step S2 was stirred and dissolved for 4-6 h to obtain a transparent polyamide solution with good flowability.

[0104] S4: The colorless polyamide acid solution obtained in step S3 was subjected to pressure filtration, impurity removal, and defoaming, and then uniformly coated on a clean glass substrate using a doctor blade, dried at 80 °C under vacuum for 2 h, and then placed in a forced air drying oven, and subjected to thermal crosslinking and solidification treatment at 100 °C, 150 °C, 200 °C, 260 °C, and 300 °C for 30 min each, and the temperature rising rate was set at 10 °C / min in each temperature zone. The CPPA film was peeled off after cooling to room temperature.

[0105] The CPPA film obtained was subjected to infrared spectrum detection, and the obtained spectrum is shown in Figure 4

[0106] Example 5: The preparation steps of the colorless transparent high-temperature-resistant polyamide film are as follows: ​S1: Into a 250 mL three-necked flask equipped with a mechanical stirring device, 162.96 g of N-methylpyrrolidone, 16.1956 g (29 mmol) of N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(4- aminobenzamide), 0.0881 g (0.15 mmol) of 2,2'-bis[(3-benzamido)-4- hydroxyphenyl]hexafluoropropane, 4.7444 g (14.54 mmol) of 5-(4- (trifluoromethyl)phenoxy)isophthalic acid, 7.7296 g (14.57 mmol) of 2,2'-bis(p- trifluorophenyl)-4,4'-biphenyldicarboxylic acid, 9.78 g of anhydrous calcium chloride, 0.06 g of triphenyl phosphite, 2.30 g of pyridine were added, and after being fully stirred and dissolved, the reaction was heated at 100-150 °C for 8-12 hours to obtain a homogeneous colorless polyamide solution.

[0107] S2: The colorless polymer slurry was precipitated and solidified in an ethanol system, and after solid-liquid separation, the solid resin was washed with ethanol for 2-3 times, and then the resin was vacuum dried at 160-180 °C for 6-10 hours to obtain a white polyamide resin.

[0108] S3: 85 g of N-methylpyrrolidone and 0.0306 g (1.6 times) of 1,3-bis(isocyanate methyl)-2-methylbenzene were added into a 250 mL three-necked flask, and 15 g of the white polyamide resin obtained in step S2 was stirred and dissolved for 4-6 h to obtain a transparent polyamide solution with good flowability.

[0109] S4: The colorless polyamide acid solution obtained in step S3 was subjected to pressure filtration, impurity removal, defoaming, and then uniformly coated on a clean glass substrate using a doctor blade, vacuum dried at 80 °C for 2 h, and then placed into a forced air drying oven, and subjected to thermal crosslinking and solidification treatment at 100 °C, 150 °C, 200 °C, 260 °C and 300 °C for 30 min at each temperature, and the temperature rising rate was set at 10 °C / min in each temperature zone. After cooling to room temperature, the CPPA film was peeled off.

[0110] The CPPA film obtained was subjected to infrared spectrum detection, and the obtained spectrum is shown in Figure 5 .

[0111] Comparative Example 1: The preparation steps of the colorless transparent high-temperature-resistant polyamide film are as follows: S1: Under stirring at room temperature in an inert atmosphere, 107.17 g of N-methylpyrrolidone, 9.5531 g (45 mmol) of 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TD), 0.1367 g (0.23 mmol) of 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane, 3.7567 g (26.61 mmol) of isophthalic acid, 5.4666 g (22.57 mmol) of diphenyl dicarboxylic acid, 6.43 g of anhydrous calcium chloride, 0.04 g of triphenyl phosphite, 3.5738 g of pyridine were added into a 250 mL three-necked flask equipped with a mechanical stirring device, and after being fully stirred and dissolved, the reaction was heated at 100-150°C for 8-12 hours to obtain a homogeneous colorless polyamide solution.

[0112] S2: The colorless polymer slurry was precipitated and solidified in an ethanol system, and after solid-liquid separation, the solid resin was washed with ethanol for 2-3 times, and then the resin was vacuum dried at 160-180°C for 6-10 hours to obtain a white polyamide resin.

[0113] S3: 85 g of N-methylpyrrolidone and 15 g of the white polyamide resin obtained in step S2 were added into a 250 mL three-necked flask, and after being stirred and dissolved for 4-6 h, a transparent polyamide solution with good fluidity was obtained.

[0114] S4: The colorless polyamide acid solution obtained in step S3 was filtered, impurities were removed, and defoaming was performed, and then it was uniformly coated on a clean glass substrate using a doctor blade, vacuum dried at 80°C for 2 h, and then placed into a forced air drying oven, and cured at 100°C, 150°C, 200°C, 260°C and 300°C for 30 min respectively, and the temperature rising rate was set at 10°C / min in each temperature zone. After cooling to room temperature, the CPPA film was peeled off.

[0115] Comparative Example 2: The preparation steps of the colorless transparent high-temperature-resistant polyamide film are as follows: S1: Under stirring at room temperature in an inert atmosphere, 107.17 g of N-methylpyrrolidone, 9.5531 g (45 mmol) of 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TD), 0.1367 g (0.23 mmol) of 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane, 3.7567 g (26.61 mmol) of isophthalic acid, 5.4666 g (22.57 mmol) of diphenyl dicarboxylic acid, 6.43 g of anhydrous calcium chloride, 0.04 g of triphenyl phosphite, 3.5738 g of pyridine were added into a 250 mL three-necked flask equipped with a mechanical stirring device, and after being fully stirred and dissolved, the reaction was heated at 100-150°C for 8-12 hours to obtain a homogeneous colorless polyamide solution.

[0116] S2: The colorless polymer slurry is precipitated and solidified in an ethanol system, washed with ethanol 2-3 times after solid-liquid separation, and then the resin is vacuum dried at 160-180°C for 6-10 hours to obtain a white polyamide resin.

[0117] S3: In a 250 mL three-necked flask, 85 g of N-methyl pyrrolidone, 0.1085 g (2.2 times) of 1,3-bis(isocyanate methyl)-2-methylbenzene, and 15 g of the white polyamide resin obtained in step S2 are sequentially added, and stirred and dissolved for 4-6 h to obtain a good flowability and transparent polyamide solution.

[0118] S4: The colorless polyamide acid solution obtained in step S3 is pressure filtered, impurity removed, defoamed, and then uniformly coated on a clean glass substrate with a doctor blade, vacuum dried at 80°C for 2 h, and then placed in a forced air drying oven, and heat crosslinked and solidified at 100°C, 150°C, 200°C, 260°C, and 300°C for 30 min each, and the temperature rising rate is set at 10°C / min in each temperature zone. Cool to room temperature and peel off the CPPA film.

[0119] Comparative Example 3: The preparation steps of the colorless and transparent high-temperature-resistant polyamide film are as follows: S1: Under stirring in an inert atmosphere at room temperature, 129.80 g of N-methyl pyrrolidone, 10.8878 g (34 mmol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 0.1241 g (0.21 mmol) of 2,2'-bis[(3-benzoylamino)-4-hydroxyphenyl]hexafluoropropane, 2.8413 g (17.10 mmol) of terephthalic acid, 9.0533 g (17.07 mmol) of 2,2'-bis(p-trifluorophenyl)-4,4'-biphenyldicarboxylic acid, 8.44 g of anhydrous calcium chloride, 0.05 g of triphenyl phosphite, and 2.70 g of pyridine are added into a 250 mL three-necked flask with a mechanical stirring device, and after stirring and dissolving, heated at 100-150°C for 8-12 h to obtain a homogeneous colorless polyamide solution.

[0120] S2: The colorless polymer slurry is precipitated and solidified in an ethanol system, washed with ethanol 2-3 times after solid-liquid separation, and then the resin is vacuum dried at 160-180°C for 6-10 hours to obtain a white polyamide resin.

[0121] S3: In a 250 mL three-necked flask, 85 g of N-methyl pyrrolidone, 0.0431 g (1.5 times) of 1,3-bis(isocyanate methyl)-2-methylbenzene, and 15 g of the white polyamide resin obtained in step S2 are sequentially added, and stirred and dissolved for 4-6 h to obtain a good flowability and transparent polyamide solution.

[0122] S4: The colorless polyamide acid solution obtained in step S3 was subjected to pressure filtration, impurity removal, defoaming, and then uniformly coated on a clean glass substrate using a doctor blade. Vacuum drying was performed at 80°C for 2h, and then the sample was placed in a forced air drying oven. Heat crosslinking and curing treatment were performed at 100°C, 150°C, 200°C, 260°C, and 300°C for 30min each, and the temperature rising rate was set at 10°C / min in each temperature zone. The CPPA film was peeled off after cooling to room temperature.

[0123] Comparative Example 4: The preparation steps of the colorless transparent high-temperature-resistant polyamide film are as follows: S1: Under stirring in an inert atmosphere at room temperature, 146.35g of N-methylpyrrolidone, 11.4979g (33mmol) of 9,9-bis(3-fluoro-4-aminophenyl)fluorene, 0.1204g (0.20mmol) of 2,2'-bis[(3-benzoylamino)-4-hydroxyphenyl]hexafluoropropane, 5.4043g (16.57mmol) of 5-(4-(trifluoromethyl)phenoxy)isophthalic acid, 8.8046g (16.60mmol) of 2,2'-bis(p-trifluorophenyl)-4,4'-biphenyldicarboxylic acid, 8.78g of anhydrous calcium chloride, 0.05g of triphenyl phosphite, and 2.62g of pyridine were added into a 250mL three-necked flask equipped with a mechanical stirring device. After being fully stirred and dissolved, the mixture was heated at 100-150°C for 8-12h to obtain a homogeneous colorless polyamide solution.

[0124] S2: The colorless polymer slurry was precipitated and solidified in an ethanol system, and the solid resin was washed with ethanol for 2-3 times after solid-liquid separation. Then the resin was vacuum dried at 160-180°C for 6-10h to obtain a white polyamide resin.

[0125] S3: 85g of N-methylpyrrolidone and 0.0393g (1.6 times) of 1,3-bis(isocyanate methyl)-2-methylbenzene were added into a 250mL three-necked flask, and 15g of the white polyamide resin obtained in step S2 was added. After being stirred and dissolved for 4-6h, a transparent polyamide solution with good fluidity was obtained.

[0126] S4: The colorless polyamide acid solution obtained in step S3 was subjected to pressure filtration, impurity removal, defoaming, and then uniformly coated on a clean glass substrate using a doctor blade. Vacuum drying was performed at 80°C for 2h, and then the sample was placed in a forced air drying oven. Heat crosslinking and curing treatment were performed at 100°C, 150°C, 200°C, 260°C, and 300°C for 30min each, and the temperature rising rate was set at 10°C / min in each temperature zone. The CPPA film was peeled off after cooling to room temperature.

[0127] The infrared spectrum of the polyamide film prepared in the above example is shown in​Figures 1 to 5 .

[0128] The polyamide films prepared in the examples and comparative examples were subjected to relevant tests of optical, mechanical properties, water absorption, etc. The results are shown in Table 1.

[0129] Table 1 Basic and application performance indicators of films

[0130] As can be seen from the test results in Table 1, compared with Comparative Example 1, Example 1 introduces a trifluoromethyl group into the chain segment. The trifluoromethyl group has strong electronegativity and large free volume, which can effectively increase the free volume between molecules, weaken the interaction between molecules, cut off the flow of electron cloud from electron donor to electron acceptor, and hinder the formation of intermolecular and intramolecular charge transfer complex (CTC). Example 2 introduces a large steric hindrance side group into the main chain, which hinders the formation of intermolecular and intramolecular CTC, further breaks the regularity of the polymer molecular chain, reduces the degree of regular arrangement of the chain segment, reduces the hydrogen bonding between polymer chains, and reduces the crystallinity of the polymer. Both of them improve the optical properties of the material from different angles.

[0131] Compared with Comparative Example 3, Example 3 introduces a large branched chain group on the basis of the asymmetric structure, which further increases the distance between the molecular chains and reduces the intermolecular force. At the same time, the effect of the trifluoromethyl group on the branched chain further improves the solubility of the polymer. Example 4 selects a flexible group containing an ether bond in the main chain. The presence of the ether bond allows the main chain to rotate and bend more freely. This high flexibility allows the polymer chain to quickly relax from a "tight aggregate state" to a "loose coil state" in the solvent, increasing the contact area with the solvent molecules, making it easier for solvent molecules to penetrate and diffuse, thereby accelerating the dissolution rate and improving the solubility. In summary, the improvement of the solubility of the polymer is more conducive to industrialized production and processing.

[0132] Example 5 uses diamines with amide structures. Amide structures can significantly enhance the mechanical strength of polymers and also control the thermal properties of polymers (Tg increases), and have certain chain flexibility and processability. Unlike pure rigid aromatic diamines, diamines with amide structures can be designed to adjust flexibility (such as introducing aliphatic chain segments) to avoid excessive decline in polymer processability. Comparative Example 4 mainly uses rigid diamine structures. The rigid backbone restricts the movement of the molecular chain and enhances the intermolecular interaction, which can effectively improve the mechanical properties and thermal properties, but reduces the solubility and processing fluidity of the polymer.

[0133] Compared with Comparative Example 2, Example 2 controls the introduction ratio of crosslinking agent, and the resin film exhibits good mechanical properties and heat resistance under the preferred process control crosslinking density; Comparative Example 2 introduces an excessive proportion of crosslinking agent, which causes the polyamide film to become hard and brittle, and the tensile strength and elongation at break indicators are significantly deteriorated, with the tensile strength being about 25% lower than that of Example 2. Therefore, by the action of the crosslinking structure rivet, the resin film can exhibit good tensile strength and heat resistance when the crosslinking agent is selected in an appropriate proportion.

[0134] Examples 1-3 can effectively reduce the packing efficiency, increase the intermolecular distance, and weaken the intermolecular interaction force by introducing a trifluoromethyl group, thereby improving the solubility of the polymer and reducing the dielectric constant. Not only can soluble polyamides be effectively prepared, but the polyamide film also has excellent optical properties; due to the mutual repulsion of adjacent fluorine atoms of the trifluoromethyl group, the fluorine atoms are not in the same plane, and the fluorine atoms in the main chain are distributed in a spiral along the carbon chain, tightly wrapping the carbon-carbon chain, making it difficult for atoms to be embedded. Moreover, the shared electron pair of the fluorine-carbon atom greatly deviates towards the fluorine atom, forming a layer of negative charge protection, and the surface energy is very low. In summary, the low molar polarization of the fluorine atom and its strong hydrophobicity can also ensure the low water absorption of the fluorine-containing polyamide.

[0135] As can be seen from the data in Table 1, Examples 1-5 can all meet the application requirements of flexible printed circuit board (FPC) substrates, and in particular, Example 2 has the best performance, with excellent optical, mechanical and thermal stability, and the water absorption of the polyamide film is less than 2%.

[0136] The above describes the present application in combination with preferred embodiments, but these embodiments are only exemplary and serve only to illustrate. On this basis, various substitutions and improvements can be made to the present application, and these all fall within the scope of protection of the present application.

Claims

1. A polyamide material, characterized in that, a main chain structure, and a linking structure that crosslinks the main chain structure; wherein the main chain structure comprises a first structural unit formed from a first aromatic diacid monomer a second structural unit formed from a second aromatic diacid monomer a third structural unit formed from a first aromatic diamine monomer and a fourth structural unit formed from a second aromatic diamine monomer containing a phenolic hydroxyl group ; wherein Ar1and Ar5are independently connected by one or more groups selected from alkylene, -O-, biphenylene, -C(=O)-, C 1-4 alkylene, and sulfone groups, said alkylene, biphenylene, and C 1-4 alkylene are optionally substituted with one or more substituents selected from C 1-4 alkyl (preferably methyl, t-butyl), haloC 1-4 alkyl (preferably trifluoromethyl), halo (preferably -Cl), substituted or unsubstituted phenyl, and substituted or unsubstituted naphthyl, the phenyl and naphthyl groups herein being optionally substituted with one or more substituents selected from C 1-4 alkyl (preferably methyl, t-butyl), haloC 1-4 alkyl (preferably trifluoromethyl), and halo (preferably -Cl); Ar2is linked to form one or more groups selected from phenylene, -0-, biphenylene, -NH-, -C(=0)-, -S-, C 1-4 alkylene, C 3-4 cycloalkylene, and sulfone, said phenylene, biphenylene, C 1-4 alkylene, and C 3-4 cycloalkylene are optionally substituted with one or more substituents selected from C 1-4 alkyl (preferably methyl, tert-butyl), haloC 1-4 alkyl (preferably trifluoromethyl), halo (preferably -F), substituted or unsubstituted fluorenyl, and substituted or unsubstituted phenyl, the phenyl and fluorenyl groups herein are optionally substituted with one or more substituents selected from C 1-4 alkyl (preferably methyl), haloC 1-4 alkyl (preferably trifluoromethyl), and halo (preferably -F); Ar3is formed by one or more groups selected from tetra-substituted phenylene, -O-, tetra-substituted biphenylene, di-substituted phenylene, -NH-, -C(=0)-, C 1-4 alkylene, sulfone and pyridinylene groups, said tetra-substituted phenylene, tetra- substituted biphenylene, di-substituted phenylene and C 1-4 alkylene is optionally substituted with one or more substituents selected from C 1-4 alkyl (preferably methyl), halo-C 1-4 alkyl (preferably trifluoromethyl), halo (preferably -F) and substituted or unsubstituted phenyl, which phenyl is optionally substituted with one or more substituents selected from C 1-4 alkyl (preferably methyl, tert-butyl), halo-C 1-4 alkyl (preferably trifluoromethyl) and halo (preferably -F); and the linking structure is formed by polymeric reaction of an aromatic diisocyanate with the phenolic hydroxyl groups in the fourth structural unit; Preferably, the linking structure is represented by Formula II: Formula II, wherein Ar4is formed by one or more groups selected from phenylene, naphthylene, C 1-4 alkylene and C 3-6 cycloalkylene, wherein phenylene, naphthylene, C 1-4 alkylene and C 3-6 cycloalkylene are optionally substituted by one or more substituents selected from C 1-4 alkyl (preferably methyl), halo-C 1-4 alkyl (preferably trifluoromethyl) and halogen (preferably -F).

2. The polyamide material of claim 1, wherein, Ar1and Ar5are independently selected from at least one of the following structures: ； Ar2is selected from at least one of the following structures: ； Ar3is selected from at least one of the following structures: wherein denotes the position at which Ar3is attached to the N atom, denotes the position at which Ar3is attached to the O atom; and / or Ar4is selected from at least one of the following structures: - C x H 2x - wherein x is an integer from 1 to 6; 。 3. The polyamide material of claim 1, wherein, the first and second aromatic diacid monomers are independently selected from one or more of: terephthalic acid, 4,4'-biphenyldicarboxylic acid, 2,5-dichloroterephthalic acid, 2,2'-biphenyldicarboxylic acid, 2-trifluoromethylterephthalic acid, 2-methylterephthalic acid, isophthalic acid, 2-methyl-4,4'-biphenyldicarboxylic acid, 2,2'-bis(trifluoromethyl)-4,4'-biphenyldicarboxylic acid, 2-trifluoromethyl-4,4'-biphenyldicarboxylic acid, 2-tert-butylisophthalic acid, 2,2'-diphenyl-4,4'-biphenyldicarboxylic acid, 2,2'-bis(p-trifluorophenyl)-4,4'-biphenyldicarboxylic acid, 2,2'-bis(a-naphthyl)-4,4'-biphenyldicarboxylic acid, 4,4'-dicarboxydiphenyl ether, 4,4'-dicarboxy diphenyl sulfone, 5-(4-trifluoromethylphenoxy)isophthalic acid, 4,4'-carbonylbiphenyl dicarboxylic acid, 2,2-bis(4-carboxyphenyl)hexafluoropropane; The first aromatic diamine monomer is selected from one or more of 2,5-difluoro-1,4-phenylenediamine, 2,2',6,6'-tetrafluorobiphenyl diamine, 2,2',6,6'-tetra(trifluoromethyl)stilbene diamine, 2,2'-bis(fluoro)stilbene diamine, 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), 2,2',2'',5'-tetra(trifluoromethyl)-[1,1',4',1''-biphenyl]-4,4''-diamine, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TD), N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(4-aminobenzamide) (AB-TFMB), 4,4'-diaminobenzanilide, 4,4'-diaminobenzenesulfone, p-aminophenyl p-aminobenzoate, 4,4'-((3-(trifluoromethyl)phenyl)methylene)diaminobiphenyl, 4,4'-((perfluorocyclobutane-1,2-diyl)bis(oxy))diamine, 4,4'-(1-(3,5-bis(trifluoromethyl)phenyl)-2,2,2-trifluoroethyl)diaminobiphenyl, 4,4'-((3,5-bis(trifluoromethyl)phenyl)methylene)diaminobiphenyl, 4-(4-(2-(4-(4-aminophenoxy)phenyl)-2-propyl)phenoxy)aniline, 3-(1-(3-aminophenyl)-2,2,2-trifluoro-1-phenylethyl)aniline, 4-(4-aminophenoxy)-3,5-bis(trifluoromethyl)aniline, bis(4-hydroxyphenyl)terephthalate, 3-(3-aminophenylthio)aniline, 3-(3-aminobenzyl)aniline, 4-(4-(4-aminophenoxy)phenoxy)aniline, 4,4'-diaminobenzenesulfone, p-aminophenyl p-aminobenzoate, 2,2'-bis(3-aminophenyl)hexafluoropropane, 4-(4-(4-aminophenoxy)-2,3,5,6-tetrafluorophenoxy)aniline; The second aromatic diamine monomer containing phenolic hydroxyl groups is selected from one or more of 4,6-diaminoresorcinol, 3,3'-diamino-4,4'-biphenyldiol, 2-amino-4-(3-amino-4-hydroxyphenoxy)phenol, 3,3'-diamino-4,4'- dihydroxydiphenylsulfone, 2,2'-bis(4-hydroxy-3-aminophenyl)propane, 2,2'-bis(3-amino-4- hydroxyphenyl)hexafluoropropane, 3-amino-N-(3-amino-4-hydroxyphenyl)-4- hydroxybenzamide, 2-amino-5-(4-(4-amino-3-hydroxyphenoxy)-2,3,5,6- tetrafluorophenoxy)phenol, 2-amino-4-(1-(3-amino-4-hydroxyphenyl)-2,2,2- trifluoro-1-phenylethyl)phenol, N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'- diyl)bis(3-hydroxy-4-aminobenzamide), 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]propane, 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane, 2,2'-bis[(3-hydroxy-4- aminophenoxy)-4-phenyl]hexafluoropropane, 2,2'-bis(trifluoromethyl)-(3-hydroxy-4- aminophenoxy)biphenyl, 2,2'-bis[(4-hydroxy-5-aminopyridin-2-yloxy)-4-phenyl]hexafluoropropane, 2-amino-5-(1-(4-amino-3-hydroxyphenyl)-1-(4-(trifluoromethyl)phenyl)ethyl)phenol; and / or The aromatic diisocyanate is selected from one or more of bis(4-isocyanatocyclohexyl)methane, isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, m-xylylene diisocyanate, toluene-2,6-diisocyanate (2,6-TDI), 1,3-bis(isocyanatomethyl)-2-methylbenzene, 1-isocyanato-4-[(4-isocyanatocyclohex-2,4-dienyl)methyl]benzene, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, 2-isocyanato-4-[(3-isocyanato-4-methylcyclohex-2,4-dienyl)methyl]-1-methylbenzene, 2,4-diisocyanato-1-methylbenzene, 3,5-diisocyanato-1-methylbenzene, 2,5-diisocyanato-1-methylbenzene, and p-phenylene diisocyanate.

4. The polyamide material of claim 1, wherein, The first structural unit, the second structural unit, the third structural unit, and the fourth structural unit are connected in a random polymerized manner.

5. The polyamide material of claim 1, wherein, The polyamide material has a structure represented by the following Formula I: Formula I wherein the main chain structure comprises a first amide segment and a second amide segment, m is the number of repetitions of the first amide segment, n is the number of repetitions of the second amide segment, m and n are independently a number greater than 0, and m:n = (9~9.5):(1~0.5); Ar1, Ar2, Ar3, Ar4, and Ar5 are defined as in claim 1.

6. The polyamide material of claim 5, wherein, The polyamide material has one of the following structures: wherein m and n are defined as in claim 5.

7. A method of making a polyamide material, characterized in that, comprising the steps of: mixing a first aromatic diacid monomer, a second aromatic diacid monomer, a first aromatic diamine monomer and a second aromatic diamine monomer containing phenolic hydroxyl, a catalyst, a cosolvent and a polymerization promoter in a first organic solvent, and heating the mixture to 100-150°C to perform a polymerization reaction, to obtain a linear polyamide resin slurry; precipitating and solidifying the linear polyamide resin slurry in a second organic solvent, and separating to obtain a linear polyamide resin; dissolving the linear polyamide resin and an isocyanate crosslinking agent in a third organic solvent to obtain a crosslinked polyamide resin prepolymer slurry; preforming the crosslinked polyamide resin prepolymer slurry and heating to 100-300°C to perform a crosslinking and solidification, to obtain the polyamide material.

8. The method of claim 7, wherein, the ratio of the sum of the molar amounts of the first aromatic diamine monomer and the second aromatic diamine monomer containing phenolic hydroxyl to the sum of the molar amounts of the first aromatic diacid monomer and the second aromatic diacid monomer is 100:(99-99.9); the proportion of the second aromatic diamine monomer containing phenolic hydroxyl is 0.5-0.7% based on the total molar amount of the first aromatic diamine monomer and the second aromatic diamine monomer containing phenolic hydroxyl; the sum of the mass of the first aromatic diamine monomer, the second aromatic diamine monomer containing phenolic hydroxyl, the first aromatic diacid monomer and the second aromatic diacid monomer is 10%-20% of the mass of the first organic solvent; and / or the addition amount of the isocyanate crosslinking agent is 1.2-1.8 times of the molar amount of the second aromatic diamine monomer containing phenolic hydroxyl.

9. The method of claim 7, wherein, the crosslinking and solidification step comprises, before heating the linear polyamide resin slurry, coating the linear polyamide resin slurry into a prepolymer film, heating the prepolymer film to perform crosslinking and solidification, to obtain a polyamide material; preferably, the heating of the prepolymer film comprises vacuum drying at 80°C for 2 hours, and then sequentially constant temperature at 100°C, 150°C, 200°C, 260°C and 300°C for 30 minutes respectively.

10. The method of claim 7, wherein, the first aromatic diacid monomer and the second aromatic diacid monomer are independently selected from one or more of the following: terephthalic acid, 4,4'-biphenyldicarboxylic acid, 2,5-dichloroterephthalic acid, 2,2'-biphenyldicarboxylic acid, 2-trifluoromethylterephthalic acid, 2-methylterephthalic acid, isophthalic acid, 2,2'-bis(trifluoromethyl)-4,4'-biphenyldicarboxylic acid, 2-trifluoromethyl-4,4'-biphenyldicarboxylic acid, 2-tert-butylisophthalic acid, 2,2'-diphenyl-4,4'-biphenyldicarboxylic acid, 2,2'-bis(p-trifluorophenyl)-4,4'-biphenyldicarboxylic acid, 2,2'-bis(α-naphthyl)-4,4'-biphenyldicarboxylic acid, 4,4'-dicarboxy diphenyl ether, 4,4'-dicarboxy diphenyl sulfone, 5-(4-trifluoromethylphenoxy)isophthalic acid, 4,4'-carbonylbiphenyl dicarboxylic acid, 2,2-bis(4-carboxyphenyl)hexafluoropropane; The first aromatic diamine monomer is selected from one or more of 2,5-difluoro-1,4-phenylenediamine, 2,2',6,6'-tetrafluorobiphenyl diamine, 2,2',6,6'-tetra(trifluoromethyl)stilbene diamine, 2,2'-bis(fluoro)stilbene diamine, 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), 2,2',2'',5'-tetra(trifluoromethyl)-[1,1',4',1''-biphenyl]-4,4''-diamine, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TD), N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(4-aminobenzamide) (AB-TFMB), 4,4'-diaminobenzanilide, 4,4'-diaminobenzenesulfone, p-aminophenyl p-aminobenzoate, 4,4'-((3-(trifluoromethyl)phenyl)methylene)diaminobiphenyl, 4,4'-((perfluorocyclobutane-1,2-diyl)bis(oxy))diamine, 4,4'-(1-(3,5-bis(trifluoromethyl)phenyl)-2,2,2-trifluoroethyl)diaminobiphenyl, 4,4'-((3,5-bis(trifluoromethyl)phenyl)methylene)diaminobiphenyl, 4-(4-(2-(4-(4-aminophenoxy)phenyl)-2-propyl)phenoxy)aniline, 3-(1-(3-aminophenyl)-2,2,2-trifluoro-1-phenylethyl)aniline, 4-(4-aminophenoxy)-3,5-bis(trifluoromethyl)aniline, bis(4-hydroxyphenyl)terephthalate, 3-(3-aminophenylthio)aniline, 3-(3-aminobenzyl)aniline, 4-(4-(4-aminophenoxy)phenoxy)aniline, 4,4'-diaminobenzenesulfone, p-aminophenyl p-aminobenzoate, 2,2'-bis(3-aminophenyl)hexafluoropropane, 4-(4-(4-aminophenoxy)-2,3,5,6-tetrafluorophenoxy)aniline; the second aromatic diamine monomer containing phenolic hydroxyl groups is selected from one or more of 4,6-diaminoresorcinol, 3,3'-diamino-4,4'-biphenyldiol, 2-amino-4-(3-amino-4-hydroxyphenoxy)phenol, 3,3'-diamino-4,4'- dihydroxydiphenylsulfone, 2,2'-bis(4-hydroxy-3-aminophenyl)propane, 2,2'-bis(3-amino-4- hydroxyphenyl)hexafluoropropane, 3-amino-N-(3-amino-4-hydroxyphenyl)-4- hydroxybenzamide, 2-amino-5-(4-(4-amino-3-hydroxyphenoxy)-2,3,5,6- tetrafluorophenoxy)phenol, 2-amino-4-(l-(3-amino-4-hydroxyphenyl)-2,2,2- trifluoro-l-phenylethyl)phenol, N,N'-(2,2'-bis(trifluoromethyl)-[l,l'-biphenyl]-4,4'- diyl)bis(3-hydroxy-4-aminobenzamide), 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]propane, 2,2'-bis[(3-benzamido)-4-hydroxyphenyl]hexafluoropropane, 2,2'-bis[(3-hydroxy-4- aminophenoxy)-4-phenyl]hexafluoropropane, 2,2'-bis(trifluoromethyl)-(3-hydroxy-4- aminophenoxy)biphenyl, 2,2'-bis[(4-hydroxy-5-aminopyridin-2-yloxy)-4-phenyl]hexafluoropropane, 2-amino-5-(l-(4-amino-3-hydroxyphenyl)-l-(4- (trifluoromethyl)phenyl)ethyl)phenol; the isocyanate crosslinking agent is selected from one or more of bis(4- isocyanatocyclohexyl)methane, isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, m-xylylene diisocyanate, toluene-2,6-diisocyanate (2,6-TDI), 1,3- bis(isocyanatomethyl)-2-methylbenzene, l-isocyanato-4-[(4-isocyanatocyclohex-2,4- dienyl)methyl]benzene, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, 2- isocyanato-4-[(3-isocyanato-4-methylcyclohex-2,4-dienyl)methyl]-l-methylbenzene, 2,4-diisocyanato-l-methylbenzene, 3,5-diisocyanato-l-methylbenzene, 2,5- diisocyanato-l-methylbenzene, and p-phenylene diisocyanate; the catalyst is selected from one or more of pyridine, 2-methylpyridine, 3- methylpyridine, and triethylamine; the co-solvent is selected from one or both of anhydrous calcium chloride and anhydrous lithium chloride; the polymerization accelerator is selected from one or both of triphenyl phosphite and dimethyl sulfoxide; the first and third organic solvents are each independently selected from one or more of N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, and cyclopentanone, preferably N-methylpyrrolidone; and / or the second organic solvent is a lower aliphatic alcohol, preferably ethanol. the isocyanate crosslinking agent is selected from one or more of bis(4- isocyanatocyclohexyl)methane, isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, m-xylylene diisocyanate, toluene-2,6-diisocyanate (2,6-TDI), 1,3- bis(isocyanatomethyl)-2-methylbenzene, l-isocyanato-4-[(4-isocyanatocyclohex-2,4- dienyl)methyl]benzene, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, 2- isocyanato-4-[(3-isocyanato-4-methylcyclohex-2,4-dienyl)methyl]-l-methylbenzene, 2,4-diisocyanato-l-methylbenzene, 3,5-diisocyanato-l-methylbenzene, 2,5- diisocyanato-l-methylbenzene, and p-phenylene diisocyanate; the catalyst is selected from one or more of pyridine, 2-methylpyridine, 3- methylpyridine, and triethylamine; the co-solvent is selected from one or both of anhydrous calcium chloride and anhydrous lithium chloride; the polymerization accelerator is selected from one or both of triphenyl phosphite and dimethyl sulfoxide; the first and third organic solvents are each independently selected from one or more of N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, and cyclopentanone, preferably N-methylpyrrolidone; and / or the second organic solvent is a lower aliphatic alcohol, preferably ethanol.

11. The method of any one of claims 7-10, wherein, The polyamide material prepared is represented by the following Formula I: Formula I wherein m is the number of repetitions of the first amide segment, n is the number of repetitions of the second amide segment, and m and n are independently numbers greater than 0, and m:n = (9-9.5):(1-0.5); Ar1, Ar2, Ar3, Ar4, and Ar5 are defined as in claim 1.

12. A polyamide film made of the polyamide material of any one of claims 1 to 6.

13. Use of the polyamide material of any one of claims 1 to 6 or the polyamide film of claim 12 as a substrate for making a flexible printed circuit board.

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