Poly(amide-imide) copolymer film and method for preparing same

Patent metadata

Field	Value
Publication number	US-11655323-B2
Application number	US-201816636233-A
Country	US
Kind code	B2
Filing date	Dec 7, 2018
Priority date	Jan 3, 2018
Publication date	May 23, 2023
Grant date	May 23, 2023

Abstract

The present invention relates to an aromatic poly(amide-imide) copolymer film having high retardation in the thickness direction and exhibiting a low moisture absorption rate, and a method for preparing the same.

First claim

The invention claimed is:

1. An aromatic poly(amide-imide) copolymer film, comprising:
an aromatic poly(amide-imide) copolymer comprising a repeating unit derived from an aromatic diamine monomer, a repeating unit derived from an aromatic dianhydride monomer, and a repeating unit derived from an aromatic dicarbonyl monomer,
wherein the aromatic poly(amide-imide) copolymer includes the repeating unit derived from the aromatic dicarbonyl monomer in an amount of 51 mol % or more based on the total moles of the repeating units derived from the aromatic dianhydride monomer and the aromatic dicarbonyl anomer,
wherein retardation (Rth) in the thickness direction of the film as measured at a wavelength of 550 nm is 3000 nm or more, and a moisture absorption rate of the film according to General Formula 1 is 3.6% r, or less:
Moisture Absorption Rate (%)=( W 1− W 2)*100/ W 2  [General Formula 1]

in the General Formula 1, W1 is a weight measured by impregnating the aromatic poly(amide-imide) copolymer film in ultrapure water for 24 hours, and
W2 is a weight measured by drying the aromatic poly(amide-imide) copolymer film after at 150° (I for 30 minutes after the impregnation, and
wherein the repeating unit derived from the aromatic dicarbonyl monomer contains 10 to 60 mol % of 4,4′-biphenyldicarbonyl repeating units, 10 to 50 mol % of isophthaloyl repeating units, and 20 to 70 mol % of terephthaloyl repeating units.

2. The aromatic poly(amide-imide) copolymer film according to claim 1 , wherein
the moisture absorption rate according to the General Formula 1 is 2.0 to 3.6%.

3. The aromatic poly(amide-imide) copolymer film according to claim 1 , wherein
a UV-cut slope (dT/dλ) of the film measured for a specimen having a thickness of 25 to 55 μm according to ASTM E424 is 2.80 or more in the range of transmittance of 10 to 80%.

4. The aromatic poly(amide-imide) copolymer film according to claim 1 , wherein
the aromatic diamine monomer includes 2,2′-bis(trifluoromethyl)-4,4′-biphenyldiamine, and
the aromatic dianhydride monomer includes 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride or cyclobutane-1,2,3,4-tetracarboxylic dianhydride.

5. The aromatic poly(amide-imide) copolymer film according to claim 1 , wherein
the aromatic poly(amide-imide) copolymer film is dispersed in a polymer substrate containing the aromatic poly(amide-imide) copolymer, and further includes one or more aromatic compounds selected from the group consisting of 2-(2′-hydroxy-5′-tert-octylphenyl)benzotriazole and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate.

6. The aromatic poly(amide-imide) copolymer film according to claim 1 , wherein
the aromatic poly(amide-imide) copolymer film has retardation (Rth) in the thickness direction with respect to a wavelength of 550 nm in an upstretched state of 3000 nm or more.

7. The aromatic poly(amide-imide) copolymer film according to claim 1 , wherein
the aromatic poly(amide-imide) copolymer film has a thickness of 1 μm to 100 μm, and
a haze of 2% or less and visible light transmittance of 98% or more.

8. A method for preparing the aromatic poly(amide-imide) copolymer film of claim 1 , comprising the steps of: reacting an aromatic diamine monomer, an aromatic dianhydride monomer and an aromatic dicarbonyl monomer to form an aromatic poly(amide-imide) copolymer; and
coating a coating solution formed by dissolving the aromatic poly(amide-imide) copolymer in an amide solvent containing an aliphatic group having 3 or more carbon atoms onto a substrate.

9. The method for preparing the aromatic poly(amide-imide) copolymer film according to claim 8 , wherein
the amide solvent containing the aliphatic group having 3 or more carbon atoms is 3-methoxy-N,N-dimethyl propionamide or N,N-dimethylpropionamide.

10. The method for preparing the aromatic poly(amide-imide) copolymer film according to claim 8 ,
wherein the coating liquid formed by dissolving the aromatic poly(amide-imide) copolymer in an amide solvent containing an aliphatic group having 3 or more carbon atoms further includes one or more aromatic compounds selected from the group of 2-(2′-hydroxy-5′-tert-octylphenyl)benzotriazole and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate.

Assignees

• Lg Chemical Ltd

Inventors

• Ryu Bi Oh
• Park Soonyong
• Park Youngseok
• Choi Il Hwan
• Tae Young Ji
• Paek Kwanyeol

Classifications

• C08J2379/08

  Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors · CPC title

• C08K5/1345

  Carboxylic esters of phenolcarboxylic acids · CPC title

• C08L2203/16

  used for films · CPC title

• C08G73/14

  Polyamide-imides · CPC title

• C08F283/00 Primary

  Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G · CPC title