Transparent polyamide-imide resin and film using same

Abstract

Disclosed are a transparent polyamide-imide resin and a film using the same, which can be colorless and transparent, can show excellent thermal stability and mechanical properties, and can have low birefringence, making it possible to serve in various fields including a semiconductor insulator, a TFT-LCD insulator, a passivation layer, a liquid crystal alignment layer, materials for optical communication, a protective film for a solar cell, a flexible display substrate and the like.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a aromaticaromatic
Rth=[(ny−nz)*d+(nx−nz)*d]/2
Here, nx is a refractive index in an x direction, ny is a refractive index in a y direction, nz is a refractive index in a z direction, and d is the thickness of the polyamide-imide film in units of 10 μm.

TABLE 1
								Tensile
			Thick.	Transmit		CTE	Bire-	strength	Retardation
	Composition	Molar ratio	(μm)	(%)	Y.I.	(ppm/° C.)	fringence	(MPa)	Ro	Rth
Ex. 1	TFDB/6FDA + CBDA + TPC	100/30:20:50	10	89.9	3.6	10.9	0.061	164	0.24	297
Ex. 2	TFDB/6FDA + CBDA + TPC	100/40:20:40	10	89.8	3.2	11.4	0.054	158	0.16	231
Ex. 3	TFDB/6FDA + CBDA + TPC	100/60:20:20	11	89.8	3.0	11.9	0.047	150	0.10	159 (144)
Ex. 4	TFDB/6FDA + CBDA + TPC	100/75:20:5	11	90.1	2.9	12.7	0.021	131	0.09	142 (129)
Ex. 5	TFDB/6FDA + CPDA + TPC	100/30:20:50	11	88.1	4.5	10.2	0.074	170	0.27	298 (271)
Ex. 6	TFDB/6FDA + CPDA + TPC	100/40:20:40	12	88.4	4.2	10.9	0.061	164	0.17	270 (245)
Ex. 7	TFDB/6FDA + CPDA + TPC	100/60:20:20	10	88.7	3.7	11.4	0.052	154	0.15	221
Ex. 8	TFDB/6FDA + CPDA + TPC	100/75:20:5	11	88.9	3.2	12.6	0.040	135	0.11	150 (136)
C. Ex. 1	TFDB/6FDA + CBDA + TPC	100/25:20:55	11	89.0	5.0	9.0	0.116	172	0.30	600 (545)
C. Ex. 2	TFDB/6FDA + BPDA + TPC	100/25:20:55	10	87.4	4.5	8.5	0.101	185	0.42	580
C. Ex. 3	TFDB/6FDA + CBDA	100/80:20	10	89.8	4.7	37.3	0.008	84	0.16	123
C. Ex. 4	TFDB/6FDA + CPDA	100/80:20	11	89.3	4.5	35.2	0.012	87	0.17	135 (122)

As is apparent from Table 1, the polyamide-imide films of Examples 1 to 8 was colorless and transparent and exhibited low birefringence and high mechanical properties and thermal stability, compared to those of the polyamide-imide films of Comparative Examples 1 to 4.

All simple modifications or variations of the present invention may be easily performed by those skilled in the art, and may be incorporated in the scope of the present invention.

Claims

1. A polyamide-imide resin, which is an imide of a polyamic acid resulting from copolymerizing an aromatic a dianhydride and an aromatic dicarbonyl compound with an aromatic diamine, wherein the aromatic dicarbonyl compound is contained in an amount of 1 to 50 mol % based on a total molar amount of the aromatic dianhydride and the aromatic dicarbonyl compound, the aromatic dianhydride includes (i) 4,4′-hexafluoroisopropylidene diphthalic anhydride (6FDA) and (ii) at least one selected from among cyclobutanetetracarboxylic dianhydride (CBDA) and cyclopentanetetracarboxylic dianhydride (CPDA), and the aromatic diamine includes 2,2′-bis(trifluoromethyl)-1,1′-biphenyl-4,4′-diamine (TFDB).

2. The polyamide-imide resin of claim 1, wherein the aromatic dicarbonyl compound includes at least one selected from the group consisting of p-terephthaloyl chloride (TPC), terephthalic acid, iso-phthaloyl dichloride, and 4,4′-benzoyl chloride 4,4′-biphenyldicarbonyl chloride.

3. The polyamide-imide resin of claim 1, wherein the (ii) at least one selected from among the cyclobutanetetracarboxylic dianhydride (CBDA) and the cyclopentanetetracarboxylic dianhydride (CPDA) is contained in an amount of 10 to 30 mol % based on the total molar amount of the aromatic dianhydride and the aromatic dicarbonyl compound.

4. The polyamide-imide resin of claim 1, wherein the aromatic diamine further includes at least one selected from the group consisting of oxydianiline (ODA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), bis(aminohydroxyphenyl)hexafluoropropane (DBOH), bis(aminophenoxy)benzene (133APB, 134APB, 144APB), bis (aminophenyl)hexafluoropropane (33-6F, 44-6F), bis (aminophenyl)sulfone (4DDS, 3DDS), bis[(aminophenoxy) phenyl]hexafluoropropane (4B DAF), bis[(aminophenoxy) phenyl]propane (6HMDA), and bis(aminophenoxy) diphenylsulfone (DBSDA).

5. The polyamide-imide resin of claim 1, wherein the aromatic dianhydride further includes at least one selected from the group consisting of biphenyltetracarboxylic dianhydride (BPDA), bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTA), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride (TDA), pyromellitic dianhydride, 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA), benzophenone tetracarboxylic dianhydride (BTDA), bis(carboxyphenyl) dimethylsilane dianhydride (SiDA), oxydiphthalic dianhydride (ODPA), bis(dicarboxyphenoxy) diphenyl sulfide dianhydride (BDSDA), sulfonyl diphthalic anhydride (SO2DPA), and (isopropylidenediphenoxy)bis(phthalic anhydride) (6HDBA).

6. A polyamide-imide film, manufactured from the polyamide-imide resin of claim 1.

7. The polyamide-imide film of claim 6, wherein the polyamide-imide film has a transmittance of 88% or more, measured at 550 nm for a film having a thickness of 8 to 12 μm, and a coefficient of thermal expansion (CTE) of 13 ppm/° C. or less, measured at 50 to 300° C. using a thermomechanical analysis method (TMA method).

8. The polyamide-imide film of claim 6, wherein the polyamide-imide film has a tensile strength of 130 MPa or more for a film having a thickness of 8 to 12 μm when measured according to ASTM D882.

9. The polyamide-imide film of claim 6, wherein the polyamide-imide film has a birefringence of 0.1 or less, an in-plane retardation (Ro) of 1 nm or less, and a thickness-direction retardation (Rth) of 300 nm or less at a thickness of 10 μm.

10. A substrate for a plastic display comprising the polyamide-imide film of claim 6.

11. A polyamide-imide film comprising the polyamideimide resin of claim 1.

12. A substrate for a plastic display comprising the polyamide-imide film of claim 11.

13. A polyamide-imide resin, which is an imide of a polyamic acid resulting from copolymerizing a dianhydride and an aromatic dicarbonyl compound with an aromatic diamine, the dianhydride includes (i) 4,4′-hexafluoroisopropylidene diphthalic anhydride (6FDA) and (ii) at least one selected from among cyclobutanetetracarboxylic dianhydride (CBDA) and cyclopentanetetracarboxylic dianhydride (CPDA), and the aromatic diamine includes 2,2′-bis(trifluoromethyl)-1,1′-biphenyl-4,4′-diamine (TFDB).