A solvent-resistant transparent polyamide-imide and polyamide-imide film

Abstract

The present invention provides a solvent-resistant transparent polyamideimide and a polyamideimide film. The polyamideimide can effectively improve the regularity of the molecular chain and obtain highly oriented in-plane crystallization by introducing a homophenyl group into the polyamideimide molecular structure; therefore, the polyamideimide not only has the excellent light transmittance and heat resistance of traditional polyamideimide, but also has good solvent tolerance.

Description

Technical Field

[0001] The invention relates to the technical field of polyimide, in particular to a solvent-resistant transparent polyamide-imide and a polyamide-imide film. Background Art

[0002] As we all know, polyimide (PI) is a high-heat-resistant resin with excellent comprehensive performance, which is widely used in many fields such as aerospace, information recording and imaging technology, special engineering plastics and green energy. Traditional polyamide-imide (PAI) is a kind of polyimide. Its main chain contains both flexible amide groups and heat-resistant aromatic imine groups. Therefore, it is considered to combine the characteristics and properties of polyamide and polyimide at the same time. It is a non-crystalline high-temperature resistant thermoplastic engineering resin, which is widely used as a material in the electrical / electronic, aerospace, aviation and automotive industries.

[0003] Although polyamide-imide has many advantages, some problems caused by its special molecular structure still limit the application of this type of material. For example, the main chain of polyamide-imide contains amide group -NHCO-. Although its heat resistance is lower than that of polyimide, it reduces the rigidity of the molecular chain, increases its solubility, and greatly reduces its dissolution resistance. Summary of the invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a solvent-resistant transparent polyamideimide and a polyamideimide film. The polyamideimide not only has the excellent light transmittance and heat resistance of traditional polyamideimide, but also has good solvent tolerance.

[0005] The present invention provides a solvent-resistant transparent polyamide-imide, the molecular structure of which is as follows:

[0006]

[0007] Wherein, a, b, c, d are the molar amounts of the corresponding repeating units, and their values ​​are all greater than 0; and X 1 is a residue derived from 4,4'-hexafluoroisopropylidene diphthalic anhydride, X 2 is a residue derived from an aromatic dianhydride or a cyclic aliphatic dianhydride, X 3 is a residue derived from pyromellitic dianhydride, X 4 is a residue derived from an aromatic dicarbonyl compound; 1 , Y 2 , Y 3 , Y 4 It is a residue derived from an aromatic diamine.

[0008] In the polyamide-imide proposed by the present invention, a homophenyl group is introduced into the molecular structure, thereby enhancing the regularity of the polyamide-imide molecular chain, inducing the polyamide-imide to form highly oriented in-plane crystals and low free volume, and while improving the solvent resistance of the obtained polyamide-imide, further reducing its thermal expansion coefficient, thereby maintaining the inherent high heat resistance and light transmittance of the polyamide-imide.

[0009] Preferably, X 1 The group structure is as follows:

[0010]

[0011] X 2 At least one of the following group structures:

[0012]

[0013] X 3 The group structure is as follows:

[0014]

[0015] X 4 At least one of the following group structures:

[0016]

[0017] Y 1 , Y 2 , Y 3 , Y 4 All or only one of the following group structures:

[0018]

[0019] Preferably, 0.05≤c / (a+b+c+d)≤0.2.

[0020] In the present invention, in order not to reduce the inherent light transmittance of the polyamide-imide, c / (a+b+c+d) is controlled between 0.05 and 0.2. When c / (a+b+c+d) exceeds 0.2, it will cause defects such as a significant increase in the yellowness index and a serious decrease in transmittance. When c / (a+b+c+d) is lower than 0.05, the improvement in solvent resistance is not obvious.

[0021] Preferably, 0.1≤a / (a+b+c+d)≤0.3.

[0022] In the present invention, in order to optimize the optical properties and heat resistance of the obtained polyamide-imide, a / (a+b+c+d) is controlled to be between 0.1 and 0.3.

[0023] Preferably, 0.2≤b / (a+b+c+d)≤0.4.

[0024] In the present invention, in order to optimize the optical properties and heat resistance of the obtained polyamide-imide, b / (a+b+c+d) is controlled to be between 0.2 and 0.4.

[0025] Preferably, 0.3≤d / (a+b+c+d)≤0.5.

[0026] In the present invention, in order to optimize the optical properties and heat resistance of the obtained polyamide-imide, d / (a+b+c+d) is controlled to be between 0.3 and 0.5.

[0027] The present invention provides a method for preparing the polyamideimide, comprising: subjecting aromatic diamine to condensation reaction with 4,4'-hexafluoroisopropylidene diphthalic anhydride, aromatic dianhydride / cyclic aliphatic dianhydride, pyromellitic dianhydride and aromatic dicarbonyl compound, and subjecting the obtained polyamic acid to imidization to obtain the polyamideimide.

[0028] The present invention also provides a polyamide-imide film, which is obtained by forming the polyamide-imide into a film.

[0029] Preferably, the polyamide-imide film has a light transmittance of more than 86% at 550 nm, a linear thermal expansion coefficient CTE of less than 10 ppm / ° C., and a solvent resistance index of less than 1%.

[0030] The invention provides a solvent-resistant transparent polyamideimide and a polyamideimide film, which can effectively improve the regularity of the molecular chain and obtain a highly oriented in-plane crystalline structure by introducing a homophenyl group into the molecular structure of polyamideimide, thereby obtaining good heat resistance and solvent resistance while maintaining the inherent colorless and transparent properties of polyamideimide. DETAILED DESCRIPTION

[0031] The technical solutions of the present invention are described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustration only and are not to be construed as limiting the scope of the present invention.

[0032] Example 1

[0033] A solvent-resistant transparent polyamide-imide and a polyamide-imide film, and a preparation method thereof comprising:

[0034] 3.2023 g (10 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) and 50 mL of N,N-dimethylacetamide (DMAc) were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and a thermometer, and nitrogen was introduced after stirring and dissolving completely at room temperature, and then 0.8885 g (2 mmol) of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA), 0.8826 g (3 mmol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 0.2181 g (1 mmol) of pyromellitic dianhydride (PMDA) were added and stirred and dissolved completely, and 0.8132 g (4 mmol) of terephthaloyl chloride (TPC) was added and stirred and reacted at room temperature for 10 hours to obtain a polyamic acid solution;

[0035] Add 1.18 g (15 mmol) of pyridine and 1.53 g (15 mmol) of acetic anhydride to the polyamic acid solution, stir and dissolve completely, heat to 90° C., stir and react for 3 hours, cool to room temperature, add excess methanol to precipitate solid, filter and rinse with methanol, and vacuum dry to obtain the polyamideimide;

[0036] The polyamideimide is added into excess N,N-dimethylacetamide (DMAc) and dissolved completely to obtain a solution with a solid content of 5 wt%. The obtained solution is evenly coated on a glass substrate to form a film, and the temperature is raised to 100° C. for 30 min under vacuum, and then the temperature is raised to 200° C. for 30 min, and then the temperature is raised to 300° C. for 1 h. After cooling to room temperature, the film is separated from the glass substrate to obtain the polyamideimide film with a thickness of 50 μm.

[0037] Example 2

[0038] A solvent-resistant transparent polyamide-imide and a polyamide-imide film, and a preparation method thereof comprising:

[0039] 3.2023 g (10 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) and 50 mL of N,N-dimethylacetamide (DMAc) were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and a thermometer, and nitrogen was introduced after stirring and dissolving completely at room temperature, and then 0.6664 g (1.5 mmol) of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA), 1.1769 g (4 mmol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 0.1091 g (0.5 mmol) of pyromellitic dianhydride (PMDA) were added and stirred and dissolved completely, and 0.8132 g (4 mmol) of terephthaloyl chloride (TPC) was added and stirred and reacted at room temperature for 10 hours to obtain a polyamic acid solution;

[0040] Add 1.18 g (15 mmol) of pyridine and 1.53 g (15 mmol) of acetic anhydride to the polyamic acid solution, stir and dissolve completely, heat to 90° C., stir and react for 3 hours, cool to room temperature, add excess methanol to precipitate solid, filter and rinse with methanol, and vacuum dry to obtain the polyamideimide;

[0041] The polyamideimide is added into excess N,N-dimethylacetamide (DMAc) and dissolved completely to obtain a solution with a solid content of 5 wt%. The obtained solution is evenly coated on a glass substrate to form a film, and the temperature is raised to 100° C. for 30 min under vacuum, and then the temperature is raised to 200° C. for 30 min, and then the temperature is raised to 300° C. for 1 h. After cooling to room temperature, the film is separated from the glass substrate to obtain the polyamideimide film with a thickness of 50 μm.

[0042] Example 3

[0043] A solvent-resistant transparent polyamide-imide and polyamide-imide film, and a preparation method thereof comprises:

[0044] 3.2023 g (10 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) and 50 mL of N,N-dimethylacetamide (DMAc) were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and a thermometer, and nitrogen was introduced after stirring and dissolving completely at room temperature, and then 1.3327 g (3 mmol) of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA), 0.5884 g (2 mmol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 0.4362 g (2 mmol) of pyromellitic dianhydride (PMDA) were added and stirred and dissolved completely, and 0.6099 g (3 mmol) of terephthaloyl chloride (TPC) was added and stirred and reacted at room temperature for 10 hours to obtain a polyamic acid solution;

[0045] Add 1.18 g (15 mmol) of pyridine and 1.53 g (15 mmol) of acetic anhydride to the polyamic acid solution, stir and dissolve completely, heat to 90° C., stir and react for 3 hours, cool to room temperature, add excess methanol to precipitate solid, filter and rinse with methanol, and vacuum dry to obtain the polyamideimide;

[0046] The polyamideimide is added into excess N,N-dimethylacetamide (DMAc) and dissolved completely to obtain a solution with a solid content of 5 wt%. The obtained solution is evenly coated on a glass substrate to form a film, and the temperature is raised to 100° C. for 30 min under vacuum, and then the temperature is raised to 200° C. for 30 min, and then the temperature is raised to 300° C. for 1 h. After cooling to room temperature, the film is separated from the glass substrate to obtain the polyamideimide film with a thickness of 50 μm.

[0047] Example 4

[0048] A solvent-resistant transparent polyamide-imide and polyamide-imide film, and a preparation method thereof comprises:

[0049] 3.2023 g (10 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) and 50 mL of N,N-dimethylacetamide (DMAc) were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and a thermometer, and nitrogen was introduced after stirring and dissolving completely at room temperature, and then 0.8885 g (2 mmol) of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA), 0.5883 g (3 mmol) of cyclobutanetetracarboxylic dianhydride (CBDA) and 0.2181 g (1 mmol) of pyromellitic dianhydride (PMDA) were added and stirred and dissolved completely, and 0.8132 g (4 mmol) of terephthaloyl chloride (TPC) was added and stirred and reacted at room temperature for 10 hours to obtain a polyamic acid solution;

[0050] Add 1.18 g (15 mmol) of pyridine and 1.53 g (15 mmol) of acetic anhydride to the polyamic acid solution, stir and dissolve completely, heat to 90° C., stir and react for 3 hours, cool to room temperature, add excess methanol to precipitate solid, filter and rinse with methanol, and vacuum dry to obtain the polyamideimide;

[0051] The polyamideimide is added into excess N,N-dimethylacetamide (DMAc) and dissolved completely to obtain a solution with a solid content of 5 wt%. The obtained solution is evenly coated on a glass substrate to form a film, and the temperature is raised to 100° C. for 30 min under vacuum, and then the temperature is raised to 200° C. for 30 min, and then the temperature is raised to 300° C. for 1 h. After cooling to room temperature, the film is separated from the glass substrate to obtain the polyamideimide film with a thickness of 50 μm.

[0052] Example 5

[0053] A solvent-resistant transparent polyamide-imide and polyamide-imide film, and a preparation method thereof comprises:

[0054] 3.2023 g (10 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) and 50 mL of N,N-dimethylacetamide (DMAc) were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and a thermometer, and nitrogen was introduced after stirring and dissolving completely at room temperature, and then 0.6664 g (1.5 mmol) of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA), 0.7844 g (4 mmol) of cyclobutanetetracarboxylic dianhydride (CBDA) and 0.1091 g (0.5 mmol) of pyromellitic dianhydride (PMDA) were added and stirred and dissolved completely, and 0.8132 g (4 mmol) of terephthaloyl chloride (TPC) was added and stirred and reacted at room temperature for 10 hours to obtain a polyamic acid solution;

[0055] Add 1.18 g (15 mmol) of pyridine and 1.53 g (15 mmol) of acetic anhydride to the polyamic acid solution, stir and dissolve completely, heat to 90° C., stir and react for 3 hours, cool to room temperature, add excess methanol to precipitate solid, filter and rinse with methanol, and vacuum dry to obtain the polyamideimide;

[0056] The polyamideimide is added into excess N,N-dimethylacetamide (DMAc) and dissolved completely to obtain a solution with a solid content of 5 wt%. The obtained solution is evenly coated on a glass substrate to form a film, and the temperature is raised to 100° C. for 30 min under vacuum, and then the temperature is raised to 200° C. for 30 min, and then the temperature is raised to 300° C. for 1 h. After cooling to room temperature, the film is separated from the glass substrate to obtain the polyamideimide film with a thickness of 50 μm.

[0057] Example 6

[0058] A solvent-resistant transparent polyamide-imide and polyamide-imide film, and a preparation method thereof comprises:

[0059] 3.2023 g (10 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) and 50 mL of N,N-dimethylacetamide (DMAc) were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and a thermometer, and nitrogen was introduced after stirring and dissolving completely at room temperature, and then 1.3327 g (3 mmol) of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA), 0.3922 g (2 mmol) of cyclobutanetetracarboxylic dianhydride (CBDA) and 0.4362 g (2 mmol) of pyromellitic dianhydride (PMDA) were added and stirred and dissolved completely, and 0.6099 g (3 mmol) of terephthaloyl chloride (TPC) was added and stirred and reacted at room temperature for 10 hours to obtain a polyamic acid solution;

[0060] Add 1.18 g (15 mmol) of pyridine and 1.53 g (15 mmol) of acetic anhydride to the polyamic acid solution, stir and dissolve completely, heat to 90° C., stir and react for 3 hours, cool to room temperature, add excess methanol to precipitate solid, filter and rinse with methanol, and vacuum dry to obtain the polyamideimide;

[0061] The polyamideimide is added into excess N,N-dimethylacetamide (DMAc) and dissolved completely to obtain a solution with a solid content of 5 wt%. The obtained solution is evenly coated on a glass substrate to form a film, and the temperature is raised to 100° C. for 30 min under vacuum, and then the temperature is raised to 200° C. for 30 min, and then the temperature is raised to 300° C. for 1 h. After cooling to room temperature, the film is separated from the glass substrate to obtain the polyamideimide film with a thickness of 50 μm.

[0062] Example 7

[0063] A solvent-resistant transparent polyamide-imide and a polyamide-imide film, and a preparation method thereof comprising:

[0064] 3.2023 g (10 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) and 50 mL of N,N-dimethylacetamide (DMAc) were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and a thermometer, and nitrogen was introduced after stirring and dissolving completely at room temperature, and then 0.8885 g (2 mmol) of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA), 0.6304 g (3 mmol) of cyclopentanetetracarboxylic dianhydride (CPDA) and 0.2181 g (1 mmol) of pyromellitic dianhydride (PMDA) were added and stirred and dissolved completely, and 0.8132 g (4 mmol) of terephthaloyl chloride (TPC) was added and stirred and reacted at room temperature for 10 hours to obtain a polyamic acid solution;

[0065] Add 1.18 g (15 mmol) of pyridine and 1.53 g (15 mmol) of acetic anhydride to the polyamic acid solution, stir and dissolve completely, heat to 90° C., stir and react for 3 hours, cool to room temperature, add excess methanol to precipitate solid, filter and rinse with methanol, and vacuum dry to obtain the polyamideimide;

[0066] The polyamideimide is added into excess N,N-dimethylacetamide (DMAc) and dissolved completely to obtain a solution with a solid content of 5 wt%. The obtained solution is evenly coated on a glass substrate to form a film, and the temperature is raised to 100° C. for 30 min under vacuum, and then the temperature is raised to 200° C. for 30 min, and then the temperature is raised to 300° C. for 1 h. After cooling to room temperature, the film is separated from the glass substrate to obtain the polyamideimide film with a thickness of 50 μm.

[0067] Example 8

[0068] A solvent-resistant transparent polyamide-imide and a polyamide-imide film, and a preparation method thereof comprising:

[0069] 3.2023 g (10 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) and 50 mL of N,N-dimethylacetamide (DMAc) were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and a thermometer, and nitrogen was introduced after stirring and dissolving completely at room temperature, and then 0.8885 g (2 mmol) of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA), 0.8826 g (3 mmol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 0.2181 g (1 mmol) of pyromellitic dianhydride (PMDA) were added and stirred and dissolved completely, and 0.4066 g (2 mmol) of terephthaloyl chloride (TPC) and 0.4066 g (2 mmol) of isophthaloyl chloride (IPC) were added, and the mixture was stirred and reacted for 10 h at room temperature to obtain a polyamic acid solution;

[0070] Add 1.18 g (15 mmol) of pyridine and 1.53 g (15 mmol) of acetic anhydride to the polyamic acid solution, stir and dissolve completely, heat to 90° C., stir and react for 3 hours, cool to room temperature, add excess methanol to precipitate solid, filter and rinse with methanol, and vacuum dry to obtain the polyamideimide;

[0071] The polyamideimide is added into excess N,N-dimethylacetamide (DMAc) and dissolved completely to obtain a solution with a solid content of 5 wt%. The obtained solution is evenly coated on a glass substrate to form a film, and the temperature is raised to 100° C. for 30 min under vacuum, and then the temperature is raised to 200° C. for 30 min, and then the temperature is raised to 300° C. for 1 h. After cooling to room temperature, the film is separated from the glass substrate to obtain the polyamideimide film with a thickness of 50 μm.

[0072] Comparative Example 1

[0073] A transparent polyamide-imide and a polyamide-imide film, and a preparation method thereof comprising:

[0074] 3.2023 g (10 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) and 50 mL of N,N-dimethylacetamide (DMAc) were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and a thermometer, and nitrogen was introduced after stirring and dissolving completely at room temperature, and then 0.8885 g (2 mmol) of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA) and 1.1769 g (4 mmol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were added and stirred and dissolved completely, and 0.8132 g (4 mmol) of terephthaloyl chloride (TPC) was added and stirred and reacted at room temperature for 10 hours to obtain a polyamic acid solution;

[0075] Add 1.18 g (15 mmol) of pyridine and 1.53 g (15 mmol) of acetic anhydride to the polyamic acid solution, stir and dissolve completely, heat to 90° C., stir and react for 3 hours, cool to room temperature, add excess methanol to precipitate solid, filter and rinse with methanol, and vacuum dry to obtain the polyamideimide;

[0076] The polyamideimide is added into excess N,N-dimethylacetamide (DMAc) and dissolved completely to obtain a solution with a solid content of 5 wt%. The obtained solution is evenly coated on a glass substrate to form a film, and the temperature is raised to 100° C. for 30 min under vacuum, and then the temperature is raised to 200° C. for 30 min, and then the temperature is raised to 300° C. for 1 h. After cooling to room temperature, the film is separated from the glass substrate to obtain the polyamideimide film with a thickness of 50 μm.

[0077] Comparative Example 2

[0078] A transparent polyamide-imide and a polyamide-imide film, and a preparation method thereof comprising:

[0079] 3.2023 g (10 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) and 50 mL of N,N-dimethylacetamide (DMAc) were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and a thermometer, and nitrogen was introduced after stirring and dissolving completely at room temperature, and then 0.8885 g (2 mmol) of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA) and 0.7844 g (4 mmol) of cyclobutanetetracarboxylic dianhydride (CBDA) were added and stirred and dissolved completely, and 0.8132 g (4 mmol) of terephthaloyl chloride (TPC) was added and stirred and reacted at room temperature for 10 hours to obtain a polyamic acid solution;

[0080] Add 1.18 g (15 mmol) of pyridine and 1.53 g (15 mmol) of acetic anhydride to the polyamic acid solution, stir and dissolve completely, heat to 90° C., stir and react for 3 hours, cool to room temperature, add excess methanol to precipitate solid, filter and rinse with methanol, and vacuum dry to obtain the polyamideimide;

[0081] The polyamideimide is added into excess N,N-dimethylacetamide (DMAc) and dissolved completely to obtain a solution with a solid content of 5 wt%. The obtained solution is evenly coated on a glass substrate to form a film, and the temperature is raised to 100° C. for 30 min under vacuum, and then the temperature is raised to 200° C. for 30 min, and then the temperature is raised to 300° C. for 1 h. After cooling to room temperature, the film is separated from the glass substrate to obtain the polyamideimide film with a thickness of 50 μm.

[0082] Comparative Example 3

[0083] A transparent polyamide-imide and a polyamide-imide film, and a preparation method thereof comprising:

[0084] 3.2023 g (10 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) and 50 mL of N,N-dimethylacetamide (DMAc) were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and a thermometer, and nitrogen was introduced after stirring and dissolving completely at room temperature, and then 0.6663 g (1.5 mmol) of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA), 0.5884 g (2 mmol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 0.5453 g (2.5 mmol) of pyromellitic dianhydride (PMDA) were added and stirred and dissolved completely, and 0.8132 g (4 mmol) of terephthaloyl chloride (TPC) was added and stirred and reacted at room temperature for 10 hours to obtain a polyamic acid solution;

[0085] Add 1.18 g (15 mmol) of pyridine and 1.53 g (15 mmol) of acetic anhydride to the polyamic acid solution, stir and dissolve completely, heat to 90° C., stir and react for 3 hours, cool to room temperature, add excess methanol to precipitate solid, filter and rinse with methanol, and vacuum dry to obtain the polyamideimide;

[0086] The polyamideimide is added into excess N,N-dimethylacetamide (DMAc) and dissolved completely to obtain a solution with a solid content of 5 wt%. The obtained solution is evenly coated on a glass substrate to form a film, and the temperature is raised to 100° C. for 30 min under vacuum, and then the temperature is raised to 200° C. for 30 min, and then the temperature is raised to 300° C. for 1 h. After cooling to room temperature, the film is separated from the glass substrate to obtain the polyamideimide film with a thickness of 50 μm.

[0087] Comparative Example 4

[0088] A solvent-resistant transparent polyamide-imide and a polyamide-imide film, and a preparation method thereof comprising:

[0089] 3.2023 g (10 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFDB) and 50 mL of N,N-dimethylacetamide (DMAc) were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and a thermometer, and nitrogen was introduced after stirring and dissolving completely at room temperature, and then 0.9773 g (2.2 mmol) of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA), 1.0297 g (3.5 mmol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 0.0654 g (0.3 mmol) of pyromellitic dianhydride (PMDA) were added and stirred and dissolved completely, and 0.8132 g (4 mmol) of terephthaloyl chloride (TPC) was added and stirred and reacted at room temperature for 10 hours to obtain a polyamic acid solution;

[0090] Add 1.18 g (15 mmol) of pyridine and 1.53 g (15 mmol) of acetic anhydride to the polyamic acid solution, stir and dissolve completely, heat to 90° C., stir and react for 3 hours, cool to room temperature, add excess methanol to precipitate solid, filter and rinse with methanol, and vacuum dry to obtain the polyamideimide;

[0091] The polyamideimide is added into excess N,N-dimethylacetamide (DMAc) and dissolved completely to obtain a solution with a solid content of 5 wt%. The obtained solution is evenly coated on a glass substrate to form a film, and the temperature is raised to 100° C. for 30 min under vacuum, and then the temperature is raised to 200° C. for 30 min, and then the temperature is raised to 300° C. for 1 h. After cooling to room temperature, the film is separated from the glass substrate to obtain the polyamideimide film with a thickness of 50 μm.

[0092] The polyamide-imide films obtained in the examples and comparative examples were tested for solvent resistance, heat resistance and light transmittance:

[0093] Solvent resistance: The obtained polyamide-imide film was immersed in a polar solvent (N-methylpyrrolidone NMP), and the thickness after immersion for 10 minutes and the thickness before immersion were measured. The solvent resistance index was calculated according to the following formula:

[0094]

[0095] In the above formula, t 0 is the thickness of the film before impregnation, t 1It is the thickness of the film after immersion for 10 minutes. The thickness is measured by using a micrometer screw at any five points on the film.

[0096] Heat resistance: The linear thermal expansion coefficient (CTE) was measured at 50 to 300 °C using a thermomechanical analyzer according to the TMA method, with a heating rate of 10 °C / min and an applied load of 100 mN;

[0097] Light transmittance: The light transmittance (T 550 ); The yellowness index was measured at 550 nm using an ultraviolet spectrophotometer according to ASTM E313.

[0098] The performance test results of the polyamide-imide films obtained in the above examples and comparative examples are shown in Table 1 below:

[0099] Table 1 Performance test results of polyamide-imide films obtained in Examples and Comparative Examples

[0100]

[0101]

[0102] It can be seen from the data in the above table that the polyamide-imide film of the embodiment of the present invention has a higher light transmittance and excellent heat resistance stability while having a more excellent solvent resistance stability than the comparative example.

[0103] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A solvent-resistant transparent polyamide-imide, It is characterized in that The molecular structure of the polyamide-imide is shown below: Wherein, a, b, c, d are the molar amounts of the corresponding repeating units, and their values ​​are all greater than 0; and X 1 is a residue derived from 4,4'-hexafluoroisopropylidene diphthalic anhydride, X 2 is a residue derived from an aromatic dianhydride or a cyclic aliphatic dianhydride, X 3 is a residue derived from pyromellitic dianhydride, X 4 is a residue derived from an aromatic dicarbonyl compound; 1 , Y 2 , Y 3 , Y 4 is a residue derived from an aromatic diamine; X 1 The group structure is as follows: X 2 At least one of the following group structures: X 3 The group structure is as follows: X 4 At least one of the following group structures: Y 1 , Y 2 , Y 3 , Y 4 All or only one of the following group structures: 0.05≤c / (a+b+c+d)≤0.

2.

2. The solvent-resistant transparent polyamide-imide according to claim 1, It is characterized in that 0.1≤a / (a+b+c+d)≤0.

3.

3. The solvent-resistant transparent polyamide-imide according to claim 1 or 2, It is characterized in that 0.2≤b / (a+b+c+d)≤0.

4.

4. The solvent-resistant transparent polyamide-imide according to claim 1 or 2, It is characterized in that 0.3≤d / (a+b+c+d)≤0.

5.

5. A method for preparing the solvent-resistant transparent polyamide-imide according to any one of claims 1 to 4, It is characterized in that include: The polyamideimide is obtained by condensing an aromatic diamine with 4,4'-hexafluoroisopropylidene diphthalic anhydride, aromatic dianhydride / cyclic aliphatic dianhydride, pyromellitic dianhydride and an aromatic dicarbonyl compound, and then the obtained polyamic acid is imidized.

6. A polyamide-imide film, It is characterized in that The polyamide-imide is prepared by forming a film of the polyamide-imide described in any one of claims 1 to 4.

7. The polyamide-imide film according to claim 6, It is characterized in that The polyamide-imide film has a light transmittance of more than 86% at 550nm, a linear thermal expansion coefficient CTE of less than 10ppm / °C, and a solvent resistance index of less than 1%.

Images