Polyamide-imide precursor, polyamide-imide film, and display device comprising same

1. A polyamide-imide precursor comprising:

in a molecular structure thereof,

a first block obtained by copolymerizing monomers including a dianhydride and a diamine;

a second block obtained by copolymerizing monomers including an aromatic dicarbonyl compound and the diamine; and

a third block obtained by copolymerizing monomers including the aromatic dicarbonyl compound and an aromatic diamine,

wherein the dianhydride for forming the first block is 2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), and the diamine for forming the first block and the second block is 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA),

wherein the aromatic diamine for forming the third block is different from 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA),

wherein a total amount of the diamine for forming the first block and the second block is larger than an amount of the dianhydride for forming the first block, and

wherein a sum of the amount of the dianhydride for forming the first block and an amount of the aromatic dicarbonyl compound for forming the second block and the third block is larger than the amount of the diamine for forming the first block and the second block,

wherein a total content of the first block and the second block is 30 to 80 mol % based on a total of 100 moles of all block copolymers,

wherein a molar ratio of the first block and the second block is 8:2 to 2:8, and

wherein the first block is formed before the second block.

2. The polyamide-imide precursor of claim 1 , wherein the aromatic dicarbonyl compound for forming the second block and the third block is one or more selected from the group consisting of terephthaloyl chloride (p-terephthaloyl chloride, TPC), terephthalic acid, iso-phthaloyl dichloride, and 4,4′-benzoyl dichloride (4,4′-benzoyl chloride).

3. The polyamide-imide precursor of claim 1 , wherein the aromatic diamine for forming the third block is one or more selected from the group consisting of 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP), bis(4-(4-aminophenoxy)phenyl)sulfone (BAPS), bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 4,4′-diaminodiphenylsulfone (4DDS), 3,3′-diaminodiphenylsulfone (3DDS), 2,2-bis(4-(4-aminophenoxy)phenylpropane) (6HMDA), 4,4′-diaminodiphenylpropane (6HDA), 4,4′-diaminodiphenylmethane (MDA), 4,4′-diaminodiphenyl sulfide (4,4′-thiodianiline), 4,4′-diaminodiphenyldiethylsilane, 4,4′-diaminodiphenylsilane (44DDS), 4,4′-diaminodiphenyl N-methyl amine, 4,4′-diaminodiphenyl N-phenylamine, 1,3-diaminobenzene (m-PDA), 1,2-diaminobenzene (o-PDA), 4,4′-oxydianiline (44′ODA), 3,3′-oxydianiline (33′ODA), 2,4-oxydianiline (24′ODA), 3,4′-oxydianiline (34′ODA), 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (APB), 4,4′-bis(3-aminophenoxy)biphenyl (M-tolidine), bistrifluoromethylbenzidine (TFDB), and 4,4′-bis(4-aminophenoxy)biphenyl (BAPB).

4. A polyamide-imide resin having a structure which is obtained by imidizing the polyamide-imide precursor of claim 1 .

5. A polyamide-imide film which is manufactured by imidizing the polyamide-imide precursor of claim 1 .

6. The polyamide-imide film of claim 5 , wherein the polyamide-imide film has a birefringence (n) of 0.030 or less, which is defined as follows: TE (transverse electric)-TM (transverse magnetic).

7. The polyamide-imide film of claim 5 , wherein the polyamide-imide film has a coefficient of linear thermal expansion (CTE) of 60 ppm/° C. or less, which is repeatedly measured twice at 50 to 250° C. using a thermomechanical analysis method (TMA method) based on a film thickness of 10 to 50 μm.

8. The polyamide-imide film of claim 5 , wherein the polyamide-imide film has a transmittance of 88% or more, which is measured at 550 nm based on a film thickness of 10 to 50 μm, and has a yellow index of 5 or less.

9. The polyamide-imide film of claim 5 , wherein the polyamide-imide film has an elongation at break of 5% or more, which is measured based on ASTM D882 (a film thickness of 10 to 50 μm).

10. An image display device comprising:

the polyamide-imide film of claim 5 .

11. A polyamide-imide resin having a structure which is obtained by imidizing the polyamide-imide precursor of claim 2 .

12. A polyamide-imide film which is manufactured by imidizing the polyamide-imide precursor of claim 2 .

13. A polyamide-imide resin having a structure which is obtained by imidizing the polyamide-imide precursor of claim 3 .

14. A polyamide-imide film which is manufactured by imidizing the polyamide-imide precursor of claim 3 .