U.S. patent number RE48,141 [Application Number 16/153,654] was granted by the patent office on 2020-08-04 for transparent polyamide-imide resin and film using same.
This patent grant is currently assigned to KOLON INDUSTRIES, INC.. The grantee listed for this patent is KOLON INDUSTRIES, INC.. Invention is credited to Chul Ha Ju, Hak Gee Jung, Hyo Jun Park.
United States Patent |
RE48,141 |
Ju , et al. |
August 4, 2020 |
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.
Inventors: |
Ju; Chul Ha (Yongin-si,
KR), Park; Hyo Jun (Yongin-si, KR), Jung;
Hak Gee (Yongin-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
KOLON INDUSTRIES, INC. |
Gwacheon-si, Gyeonggi-do |
N/A |
KR |
|
|
Assignee: |
KOLON INDUSTRIES, INC. (Seoul,
KR)
|
Family
ID: |
1000004426050 |
Appl.
No.: |
16/153,654 |
Filed: |
October 5, 2018 |
PCT
Filed: |
December 26, 2014 |
PCT No.: |
PCT/KR2014/012882 |
371(c)(1),(2),(4) Date: |
June 23, 2016 |
PCT
Pub. No.: |
WO2015/099478 |
PCT
Pub. Date: |
July 02, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
15107634 |
Dec 26, 2014 |
9580555 |
Feb 28, 2017 |
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Foreign Application Priority Data
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Dec 26, 2013 [KR] |
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10-2013-0164009 |
Dec 24, 2014 [KR] |
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10-2014-0188216 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G
73/14 (20130101); C08J 5/18 (20130101); C08J
5/18 (20130101); C08G 73/1003 (20130101); C08L
79/08 (20130101); C08G 73/1003 (20130101); C08L
79/08 (20130101); C08G 73/14 (20130101); C08J
2379/08 (20130101); C08J 2379/08 (20130101) |
Current International
Class: |
C08G
73/00 (20060101); C08G 73/10 (20060101); C08L
79/08 (20060101); C08J 5/18 (20060101); C08G
73/14 (20060101); C08G 79/08 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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103282414 |
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Sep 2013 |
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CN |
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10-2013-0071650 |
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Jul 2013 |
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KR |
|
20130071650 |
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Jul 2013 |
|
KR |
|
1020130071650 |
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Jul 2013 |
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KR |
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10-2013-0110589 |
|
Oct 2013 |
|
KR |
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2013/170135 |
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Apr 2015 |
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KR |
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201313785 |
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Apr 2013 |
|
TW |
|
I472556 |
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Feb 2015 |
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TW |
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2012/144563 |
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Oct 2012 |
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WO |
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2013/170135 |
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Nov 2013 |
|
WO |
|
Other References
International Search Report for PCT/KR2014/012882 dated Apr. 9,
2015. cited by applicant .
International Search Report; Communication issued by the
International Searching Authority in corresponding International
application No. PCT/KR2014/012882, dated Apr. 9, 2015. cited by
applicant .
Jang et al., "The optical and dielectric characterization of
light-colored fluorinated polyimides based on
1,3-bis(4-amino-2-trifluoromethylphenoxy)benzene", Materials
Chemistry and Physics, 2007, vol. 104, pp. 342-349. cited by
applicant .
Machine translation of KR 1020130071650. cited by examiner .
Taiwanese Intellectual Property Office; Communication dated Jun.
30, 2016 in counterpart Application No. 103145580. cited by
applicant.
|
Primary Examiner: Kugel; Timothy J.
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
The invention claimed is:
1. A polyamide-imide resin, which is an imide of a polyamic acid
resulting from copolymerizing .[.an aromatic.]. .Iadd.a
.Iaddend.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.].
.Iadd.4,4'-biphenyldicarbonyl chloride.Iaddend..
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-dicar-
boxylic 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 .mu.m, and a coefficient of
thermal expansion (CTE) of 13 ppm/.degree. C. or less, measured at
50 to 300.degree. 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 .mu.m 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 .mu.m.
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.
.Iadd.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).
.Iaddend.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a .Iadd.reissue application of U.S. Pat. No.
9,580,555, which was filed as U.S. patent application Ser. No.
15/107,634 on December 26, 2014 and issued on Feb. 28, 2017, which
issued from .Iaddend.National .[.Stage.]. .Iadd.State .Iaddend.of
International Application No. PCT/KR2014/012882, filed Dec. 26,
2014, claiming priority based on Korean Patent Application Nos.
10-2013-0164009 filed on Dec. 26, 2013 and 10-2014-018826 filed on
Dec. 24, 2014, the contents of all of which are incorporated herein
by reference in its entirety.
TECHNICAL FIELD
The present invention relates to a transparent polyamide-imide
resin and a film using the same and, more particularly, to a
transparent polyamide-imide resin and a film using the same, which
may exhibit superior thermal stability and mechanical properties
and low birefringence, making it possible to serve as a substrate
for a plastic display.
BACKGROUND ART
Generally, a polyimide film is formed from a polyimide resin. Such
a polyimide resin is a highly heat-resistant resin prepared by
subjecting an aromatic dianhydride and an aromatic diamine or an
aromatic diisocyanate to solution polymerization, thus preparing a
polyamic acid derivative, which is then subjected to a ring-closing
reaction and dehydration at a high temperature so as to be
imidized.
In the preparation of the polyimide resin, examples of the aromatic
dianhydride may include pyromellitic dianhydride (PMDA),
biphenyltetracarboxylic dianhydride (BPDA), etc., and examples of
the aromatic diamine may include oxydianiline (ODA),
p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA),
methylenedianiline (MDA), bisaminophenylhexafluoropropane (HFDA),
etc.
Since a polyimide resin is a very strongly heat-resistant resin,
which is insoluble and infusible, and is superior in terms of
thermal oxidation resistance, heat resistance, radiation
resistance, low-temperature characteristics, chemical resistance
and the like, it has been utilized in a variety of fields including
those of advanced heat-resistant materials, such as automotive
materials, aircraft materials, spacecraft materials, etc., and
electronic materials such as insulation coating materials,
insulating films, semiconductors, electrode protective films for
TFT-LCDs, etc.
However, a polyimide resin is brown- or yellow-colored,
attributable to its high aromatic ring density, and thus has low
transmittance in the visible light range, and also, is unsuitable
for use in an optical member due to the high birefringence
thereof.
In order to impart transparency to a polyimide having a deep brown
and yellow color, a linkage group (--O--, --SO.sub.2--, --CO--,
--CF.sub.3CCF.sub.3--) or a side chain having a relatively large
free volume is introduced to the main chain, thus minimizing the
formation of an intermolecular or intramolecular charge transfer
complex, whereby transparency may be realized.
However, such a transparent polyimide film may have decreased heat
resistance due to the introduced functional group. This is
considered to be due to the charge transfer complex, and the film
becomes transparent but its heat resistance is decreased. When heat
resistance is decreased in this way, the transparent polyimide film
is difficult to apply to advanced material fields including
displays or semiconductors, which require high processing
temperatures. To solve this problem, attempts have been made to
polymerize monomers in the solvent after purification, but without
any significant increase in transmittance.
U.S. Pat. No. 5,053,480 discloses the use of an alicyclic
dianhydride component instead of an aromatic dianhydride. The
formation of a solution or a film is improved in transparency and
color compared to the purification method, but the increase in
transmittance is limited and thus unsatisfactory transmittance
results. Also, the thermal and mechanical properties are
deteriorated.
U.S. Pat. Nos. 4,595,548, 4,603,061, 4,645,824, 4,895,972,
5,218,083, 5,093,453, 5,218,077, 5,367,046, 5,338,826, 5,986,036,
and 6,232,428, and Korean Patent Application Publication No.
2003-0009437 disclose the preparation of a novel polyimide having
improved transmittance and color transparency in the range within
which thermal properties are not significantly deteriorated using a
linkage group such as --O--, --SO.sub.2--, CH.sub.2--, etc., a
monomer having a bent structure connected to an m-position rather
than a p-position, or aromatic dianhydride and aromatic diamine
monomers having a substituent such as --CF.sub.3, etc. However, the
above polyimide has high birefringence.
Meanwhile, a conventional glass substrate is difficult to realize
flexible properties and may be easily broken, making it difficult
to use in real-world applications. To manufacture a thin
lightweight substrate, a conventional glass substrate is coated
with a polyimide material, after which the glass is separated, or
it is formed on a polyimide film, in addition to the use of the
thin glass substrate. When a colorless transparent polyimide film
is applied to display fields, it may be utilized for display
devices having various shapes, may exhibit flexible properties, and
is thin, lightweight and unbreakable.
Therefore, a transparent polyimide, which is to be applied to
display processes, needs superior thermal stability that may endure
display processing, high mechanical properties for preventing the
breakage thereof, and low birefringence to ensure a desired viewing
angle.
DISCLOSURE
Technical Problem
Accordingly, the present invention is intended to provide a
transparent polyamide-imide resin and a film using the same, which
are suitable for use in a substrate for a plastic display owing to
superior thermal stability and mechanical properties and low
birefringence thereof.
In addition, the present invention is intended to provide a
substrate for a plastic display, which has increased thermal
stability and mechanical properties and low birefringence.
Technical Solution
An embodiment of the present invention provides a polyamide-imide
resin, which is an imide of a polyamic acid resulting from
copolymerizing an .[.aromatic.]. 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 the 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).
In a preferred embodiment of the present invention, the aromatic
dicarbonyl compound may include at least one selected from the
group consisting of p-terephthaloyl chloride (TPC), terephthalic
acid, iso-phthaloyl dichloride, and .[.4,4'-benzoyl chloride.].
.Iadd.4,4'-biphenyldicarbonyl chloride.Iaddend..
In a preferred embodiment of the present invention, the (ii) at
least one selected from among the cyclobutanetetracarboxylic
dianhydride (CBDA) and the cyclopentanetetracarboxylic dianhydride
(CPDA) may be contained in an amount of 10 to 30 mol % based on the
total molar amount of the .[.aromatic.]. dianhydride and the
aromatic dicarbonyl compound.
In a preferred embodiment of the present invention, the aromatic
diamine may further include 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 (4BDAF), bis[(aminophenoxy) phenyl]propane
(6HMDA), and bis(aminophenoxy) diphenylsulfone (DBSDA).
In a preferred embodiment of the present invention, the
.[.aromatic.]. dianhydride may further include 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-dicar-
boxylic 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) diphenylsulfide dianhydride (BDSDA),
sulfonyl diphthalic anhydride (SO2DPA), and
(isopropylidenediphenoxy)bis(phthalic anhydride) (6HDBA).
.Iadd.In a preferred embodiment of the present invention provides a
polyamide-imide resin, which is an imide of a polyamic acid
resulting from copolymerizing an 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).
.Iaddend.
Another embodiment of the present invention provides a
polyamide-imide film, manufactured from the above polyamide-imide
resin.
In a preferred embodiment of the present invention, the
polyamide-imide film may have a transmittance of 88% or more,
measured at 550 nm, for a film having a thickness of 8 to 12 .mu.m,
and a coefficient of thermal expansion (CTE) of 13 ppm/.degree. C.
or less, measured at 50 to 300.degree. C. using a thermomechanical
analysis method (TMA method).
In a preferred embodiment of the present invention, the
polyamide-imide film may have a tensile strength of 130 MPa or more
for a film having a thickness of 8 to 12 .mu.m when measured
according to ASTM D882.
In a preferred embodiment of the present invention, the
polyamide-imide film may have 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 .mu.m.
Still another embodiment of the present invention provides a
substrate for a plastic display including the above polyamide-imide
film.
Advantageous Effects
According to the present invention, a polyamide-imide resin and a
film using the same are colorless and transparent, show excellent
thermal stability and mechanical properties, and have low
birefringence, making them suitable for use 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.
BEST MODE
Unless otherwise defined, all the technical and scientific terms
used herein have the same meanings as those typically understood by
those skilled in the art to which the present invention belongs.
Generally, the nomenclature used herein is well known in the art
and is typical.
As used herein, when any part "includes" any element, this means
that another element is not excluded but may be further included
unless otherwise specifically mentioned.
In the foregoing and following description, the term "imidization"
is defined to include "amidization", and the term "imide" is
defined to include "amide".
An aspect of the present invention pertains to a polyamide-imide
resin, which is an imide of a polyamic acid resulting from
copolymerizing an .[.aromatic.]. dianhydride and an aromatic
dicarbonyl compound with an aromatic diamine. In the preparation of
the polyamic acid, 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).
Another aspect of the present invention pertains to a
polyamide-imide film made of the polyamide-imide resin and a
substrate for a plastic display including the polyamideimide
film.
Hereinafter, a detailed description will be given of the present
invention.
The present invention addresses a polyamide-imide resin and a film
using the same, which are suitable for use in a substrate for a
plastic display owing to superior thermal stability and mechanical
properties and low birefringence thereof. The polyamide-imide resin
is an imide of a polyamic acid resulting from copolymerizing an
.[.aromatic.]. dianhydride, an aromatic dicarbonyl compound and an
aromatic diamine, and a film using the same may be provided. As
such, 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).
The aromatic dicarbonyl compound may include at least one selected
from the group consisting of p-terephthaloyl chloride (TPC),
terephthalic acid, iso-phthaloyl dichloride, and .[.4,4'-benzoyl
chloride.]. .Iadd.4,4'-biphenyldicarbonyl chloride.Iaddend..
The aromatic dicarbonyl compound has a benzene ring and may thus
exhibit high thermal stability and mechanical properties, but has
high birefringence due thereto. Also, the cycloaliphatic
dianhydride, such as cyclobutanetetracarboxylic dianhydride (CBDA),
cyclopentanetetracarboxylic dianhydride (CPDA) and the like, has
low birefringence but may deteriorate thermal stability and
mechanical properties.
However, when 2,2'-bis(trifluoromethyl)-1,1'-biphenyl-4,4'-diamine
(TFDB) is used as the diamine, thermal stability and optical
properties may increase. Also, when the .[.aromatic.]. dianhydride,
the aromatic dicarbonyl compound and the aromatic diamine are
copolymerized in amounts controlled within specific ranges, the
thermal stability, mechanical properties and optical properties may
be improved and thus balanced.
In the present invention, the aromatic diamine may further include
an additional aromatic diamine, in addition to bistrifluoromethyl
benzidine (TFDB), in the interest of thermal stability and
birefringence, and the additional aromatic diamine may include, but
is not limited to, 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 (ODDS, 3DDS), bis
[(aminophenoxy)phenyl]hexafluoropropane (4BDAF), bis
[(aminophenoxy)phenyl]propane (6HMDA), and bis
(aminophenoxy)diphenylsulfone (DBSDA).
In the present invention, the .[.aromatic.]. dianhydride may
further include an additional .[.aromatic.]. dianhydride, in
addition to 4,4'-hexafluoroisopropylidene diphthalic anhydride
(6FDA) and at least one selected from among
cyclobutanetetracarboxylic dianhydride (CBDA) and
cyclopentanetetracarboxylic dianhydride (CPDA), in the interest of
thermal stability, mechanical properties and optical properties,
and the additional .[.aromatic.]. dianhydride may include, but is
not limited to, 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-dicar-
boxylic 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).
The polyamide-imide resin according to the present invention is
obtained by polymerizing an aromatic diamine with an .[.aromatic.].
dianhydride and an aromatic dicarbonyl compound, followed by
imidization. In order to attain desired thermal stability,
mechanical properties and birefringence, the .[.aromatic.].
dianhydride and the aromatic dicarbonyl compound are copolymerized
with the diamine at an equivalent ratio of 1:1, thus preparing a
polyamic acid solution. The polymerization conditions are not
particularly limited, but polymerization is preferably performed at
-10 to 80.degree. C. for 2 to 48 hr in an inert atmosphere.
In the present invention, a solvent may be used for solution
polymerization of the monomers, and is not particularly limited so
long as it dissolves polyamic acid, and preferably includes at
least one polar solvent selected from among m-cresol,
N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF),
dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), acetone, and
.[.diethyl acetate.]. .Iadd.ethyl acetate.Iaddend.. In addition
thereto, a low-boiling-point solvent, such as tetrahydrofuran (THF)
or chloroform, or a solvent characterized by low absorption, such
as .gamma.-butyrolactone, may be utilized.
The amount of the solvent is not particularly limited, but is
preferably 50 to 95 wt %, and more preferably 70 to 90 wt %, based
on the total amount of the polyamic acid solution, in order to
obtain a polyamic acid solution having appropriate molecular weight
and viscosity.
Since the amount of the aromatic dicarbonyl compound that is added
for the reaction may affect the thermal stability, mechanical
properties and birefringence of the resin and film, the aromatic
dicarbonyl compound is added in an amount of 1 to 50 mol %, and
preferably 5 to 50 mol %, based on the total molar amount of the
.[.aromatic.]. dianhydride and the aromatic dicarbonyl compound so
as not to deteriorate the inherent properties of the corresponding
polyamide-imide.
If the amount of the aromatic dicarbonyl compound exceeds 50 mol %
based on the total molar amount of the .[.aromatic.]. dianhydride
and the aromatic dicarbonyl compound, the thermal stability and
mechanical properties may increase but the optical properties, such
as a yellow index or transmittance, may decrease. In particular,
the birefringence value may increase, making it difficult to use
the resulting film as a display substrate.
On the other hand, if the amount of the aromatic dicarbonyl
compound is less than 1 mol % based on the total molar amount of
the .[.aromatic.]. dianhydride and the aromatic dicarbonyl
compound, the optical properties may increase but the thermal
stability and mechanical properties may decrease, and thus twisting
and breakage may occur in the display fabrication process.
Of the .[.aromatic.]. dianhydride, (ii) at least one selected from
among cyclobutanetetracarboxylic dianhydride (CBDA) and
cyclopentanetetracarboxylic dianhydride (CPDA) is used in an amount
of 10 to 30 mol % based on the total molar amount of the
.[.aromatic.]. dianhydride and the aromatic dicarbonyl compound,
thereby uniformly improving optical properties in the intended
wavelength range and uniformly increasing thermal stability and
mechanical properties.
The polyamic acid solution thus obtained is imidized to yield a
polyamide-imide resin. The useful imidization method may be
appropriately selected from among known imidization processes,
examples of which include thermal imidization, chemical
imidization, or a combination of thermal imidization and chemical
imidization.
The polyamide-imide film may be obtained by casting the polyamic
acid on a support and then performing the above imidization
process.
Specifically, chemical imidization is performed by adding the
polyamic acid solution with a dehydrating agent including an acid
anhydride such as acetic anhydride, etc., and an imidization
catalyst including a tertiary amine such as isoquinoline,
.beta.-picoline, pyridine, etc. Also, thermal imidization or a
combination of thermal imidization and chemical imidization may be
controlled or varied depending on the kind of polyamic acid
solution, the thickness of the resulting polyamide-imide film,
etc.
More specifically, the polyamide-imide film is manufactured using a
combination of thermal imidization and chemical imidization in a
manner in which the polyamic acid solution is added with a
dehydrating agent and an imidization catalyst, cast on a support,
heated at 80 to 200.degree. C., and preferably 100 to 180.degree.
C., to activate the dehydrating agent and the imidization catalyst,
partially cured and dried, and then heated at 200 to 400.degree. C.
for 5 to 400 sec, thereby obtaining a polyamide-imide film.
Alternatively, the polyamide-imide film may be manufactured from
the polyamic acid solution as follows. Specifically, the polyamic
acid solution is imidized, after which the imidized solution is
added to the second solvent, precipitated, filtered and dried, thus
obtaining a polyamide-imide resin solid, which is then dissolved in
the first solvent to prepare a polyamide-imide solution, following
by a film-forming process, resulting in a desired film.
When the polyamic acid solution is imidized, the imidization
process, such as thermal imidization, chemical imidization, or a
combination of thermal imidization and chemical imidization as
mentioned above, may be performed. In the imidization process
through a combination of thermal imidization and chemical
imidization, the obtained polyamic acid solution is added with a
dehydrating agent and an imidization catalyst and heated at 20 to
180.degree. C. for 1 to 12 hr and thus imidized.
The first solvent may be the same as the solvent used upon
polymerization of the polyamic acid solution, and the second
solvent may be a solvent having lower polarity than the first
solvent in order to attain the polyamide-imide resin solid.
Specific examples of the second solvent may include at least one
selected from among water, alcohols, ethers, and ketones. The
amount of the second solvent is not particularly limited, and is
preferably 5 to 20 times the weight of the polyamic acid
solution.
The polyamide-imide resin solid thus obtained is filtered and is
then preferably dried at 50 to 120.degree. C. for 3 to 24 hr taking
into consideration the boiling point of the second solvent.
In the film-forming process, the polyamide-imide solution, in which
the polyamide-imide resin solid is dissolved, is cast on the
support, and then heated for 1 min to 8 hr while the temperature
thereof is gradually increased in the range from 40 to 400.degree.
C., yielding a polyamide-imide film.
In the present invention, the polyamide-imide film thus obtained is
heat treated once more so as to remove thermal hysteresis and
residual stress from the film, thus ensuring stable thermal
properties of the film. This additional heat treatment is carried
out at 300 to 500.degree. C. for 1 min to 3 hr, and the film after
heat treatment has a residual volatile content of 5% or less, and
preferably 3% or less.
According to the present invention, the obtained polyamideimide
resin has a weight average molecular weight of 150,000 to 180,000,
a viscosity of 700 to 900 poise, and a glass transition temperature
of 300.degree. C. or higher.
Also, the polyamide-imide film according to the present invention
has a transmittance of 88% or more, measured at 550 nm for a film
having a thickness of 8 to 12 .mu.m, a yellow index of 5 or less,
and a coefficient of thermal expansion (CTE) of ppm/.degree. C. or
less, measured at 50 to 300.degree. C. using a thermomechanical
analysis method (TMA method).
Also, the polyamide-imide film according to the present invention
has a tensile strength of 130 MPa or more for a film having a
thickness of 8 to 12 .mu.m upon measurement based on ASTM D882, 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 .mu.m.
As mentioned above, the polyamide-imide film according to the
present invention is colorless and transparent, shows excellent
thermal stability and mechanical properties, and has low
birefringence, and can thus be useful 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.
MODE FOR INVENTION
A better understanding of the present invention may be obtained
through the following examples, which are set forth to illustrate,
but are not to be construed to limit the scope of the present
invention.
Example 1
While nitrogen was passed through a 1 L reactor equipped with a
stirrer, a nitrogen injector, a dropping funnel, a temperature
controller and a condenser, 716 g of N,N-dimethylacetamide (DMAc)
was added into the reactor, the temperature of the reactor was set
to 25.degree. C., 57.64 g (0.18 mol) of TFDB was dissolved, and the
resultant solution was maintained at 25.degree. C. Further, 23.99 g
(0.054 mol) of 6FDA and 7.06 g (0.036 mol) of CBDA were added and
then stirred for a predetermined period of time and thus dissolved
and allowed to react. The temperature of the solution was then
maintained at 15.degree. C., after which 18.27 g (0.09 mol) of TPC
was added and allowed to react at 25.degree. C. for 12 hr, thus
obtaining a polyamic acid solution having a solid content of 13 wt
% and a viscosity of 860 poise.
The polyamic acid solution was added with 34.17 g of pyridine and
44.12 g of acetic anhydride, stirred for 30 min, further stirred at
70.degree. C. for 1 hr, cooled to room temperature, and
precipitated with 20 L of methanol, after which the precipitated
solid was filtered, ground and then dried at 100.degree. C. for 6
hr in a vacuum, yielding 95 g of a polyamide-imide copolymer in
solid powder form.
The polyamide-imide solid powder was found to have an average
particle size of 70 to 80 .mu.m through particle size measurement,
and a weight average molecular weight of 174,000 through molecular
weight measurement.
In the foregoing and following description, the average particle
size of the polyamide-imide solid powder was determined by
measuring the particle size thereof three times using a particle
size analyzer (S3500, Microtrac) and then averaging them. The
precipitated solid was dried and the resulting copolymer powder was
used as an analytical sample, and the weight average molecular
weight was measured by drying the precipitated solid to obtain a
copolymer powder which was then dissolved at a concentration of
about 1% in N,N-dimethylacetamide (DMAc), filtered via a 0.45 .mu.m
PTFE syringe filter, injected, and then subjected to GPC (Gel
Permeation Chromatography).
95 g of the polyamide-imide copolymer in solid powder form was
dissolved in 768 g of DMAc, thus obtaining an 11 wt % solution. The
solution thus obtained was applied onto a stainless plate, cast to
100 .mu.m, dried using hot air at 150.degree. C. for 1 hr, at
200.degree. C. for 1 hr, and at 300.degree. C. for 30 min, and then
slowly cooled, after which the resulting film was separated from
the stainless plate, thus obtaining a 10 .mu.m thick
polyamide-imide film, which was then subjected to final heat
treatment at 300.degree. C. for 10 min.
Example 2
While nitrogen was passed through a 1 L reactor equipped with a
stirrer, a nitrogen injector, a dropping funnel, a temperature
controller and a condenser, 744 g of N,N-dimethylacetamide (DMAc)
was added into the reactor, the temperature of the reactor was set
to 25.degree. C., 57.64 g (0.18 mol) of TFDB was dissolved, and the
resultant solution was maintained at 25.degree. C. Further, 31.99 g
(0.072 mol) of 6FDA and 7.06 g (0.036 mol) of CBDA were added and
then stirred for a predetermined period of time and thus dissolved
and allowed to react. The temperature of the solution was then
maintained at 15.degree. C., after which 14.62 g (0.072 mol) of TPC
was added and allowed to react at 25.degree. C. for 12 hr, thus
obtaining a polyamic acid solution having a solid content of 13 wt
% and a viscosity of 830 poise.
The polyamic acid solution was added with 34.17 g of pyridine and
44.12 g of acetic anhydride, stirred for 30 min, further stirred at
70.degree. C. for 1 hr, cooled to room temperature, and
precipitated with 20 L of methanol, after which the precipitated
solid was filtered, ground and then dried at 100.degree. C. for 6
hr in a vacuum, yielding 104 g of a polyamide-imide copolymer in
solid powder form.
The polyamide-imide solid powder was found to have an average
particle size of 70 to 80 .mu.m through particle size measurement
and a weight average molecular weight of 163,000 through molecular
weight measurement.
104 g of the polyamide-imide copolymer in solid powder form was
dissolved in 841 g of DMAc, thus obtaining an 11 wt % solution. The
solution thus obtained was applied onto a stainless plate, cast to
100 .mu.m, dried using hot air at 150.degree. C. for 1 hr, at
200.degree. C. for 1 hr, and at 300.degree. C. for 30 min, and then
slowly cooled, after which the resulting film was separated from
the stainless plate, thus obtaining a 10 .mu.m thick
polyamide-imide film, which was then subjected to final heat
treatment at 300.degree. C. for 10 min.
Example 3
While nitrogen was passed through a 1 L reactor equipped with a
stirrer, a nitrogen injector, a dropping funnel, a temperature
controller and a condenser, 803 g of N,N-dimethylacetamide (DMAc)
was added into the reactor, the temperature of the reactor was set
to 25.degree. C., 57.64 g (0.18 mol) of TFDB was dissolved, and the
resultant solution was maintained at 25.degree. C. Further, 47.98 g
(0.108 mol) of 6FDA and 7.06 g (0.036 mol) of CBDA were added and
stirred for a predetermined period of time and thus dissolved and
allowed to react. The temperature of the solution was then
maintained at 15.degree. C., after which 7.31 g (0.036 mol) of TPC
was added and allowed to react at 25.degree. C. for 12 hr, thus
obtaining a polyamic acid solution having a solid content of 13 wt
% and a viscosity of 815 poise.
The polyamic acid solution was added with 34.17 g of pyridine and
44.12 g of acetic anhydride, stirred for 30 min, further stirred at
70.degree. C. for 1 hr, cooled to room temperature, and
precipitated with 20 L of methanol, after which the precipitated
solid was filtered, ground and then dried at 100.degree. C. for 6
hr in a vacuum, yielding 110 g of a polyamide-imide copolymer in
solid powder form.
The polyamide-imide solid powder was found to have an average
particle size of 70 to 80 .mu.m through particle size measurement
and a weight average molecular weight of 157,000 through molecular
weight measurement.
110 g of the polyamide-imide copolymer in solid powder form was
dissolved in 890 g of DMAc, thus obtaining an 11 wt % solution. The
solution thus obtained was applied onto a stainless plate, cast to
100 .mu.m, dried using hot air at 150.degree. C. for 1 hr, at
200.degree. C. for 1 hr, and at 300.degree. C. for 30 min, and then
slowly cooled, after which the resulting film was separated from
the stainless plate, thus obtaining an 11 .mu.m thick
polyamide-imide film, which was then subjected to final heat
treatment at 300.degree. C. for 10 min.
Example 4
While nitrogen was passed through a 1 L reactor equipped with a
stirrer, a nitrogen injector, a dropping funnel, a temperature
controller and a condenser, 846 g of N,N-dimethylacetamide (DMAc)
was added into the reactor, the temperature of the reactor was set
to 25.degree. C., 57.64 g (0.18 mol) of TFDB was dissolved, and the
resultant solution was maintained at 25.degree. C. Further, 59.97 g
(0.135 mol) of 6FDA and 7.06 g (0.036 mol) of CBDA were added and
stirred for a predetermined period of time and thus dissolved and
allowed to react. The temperature of the solution was then
maintained at 15.degree. C., after which 1.83 g (0.009 mol) of TPC
was added and allowed to react at 25.degree. C. for 12 hr, thus
obtaining a polyamic acid solution having a solid content of 13 wt
% and a viscosity of 840 poise.
The polyamic acid solution was added with 34.17 g of pyridine and
44.12 g of acetic anhydride, stirred for 30 min, further stirred at
70.degree. C. for 1 hr, cooled to room temperature, and
precipitated with 20 L of methanol, after which the precipitated
solid was filtered, ground and then dried at 100.degree. C. for 6
hr in a vacuum, yielding 114 g of a polyamide-imide copolymer in
solid powder form.
The polyamide-imide solid powder was found to have an average
particle size of 70 to 80 .mu.m through particle size measurement
and a weight average molecular weight of 172,000 through molecular
weight measurement.
114 g of the polyamide-imide copolymer in solid powder form was
dissolved in 922 g of DMAc, thus obtaining an 11 wt % solution. The
solution thus obtained was applied onto a stainless plate, cast to
100 .mu.m, dried using hot air at 150.degree. C. for 1 hr, at
200.degree. C. for 1 hr, and at 300.degree. C. for 30 min, and then
slowly cooled, after which the resulting film was separated from
the stainless plate, thus obtaining an 11 .mu.m thick
polyamide-imide film, which was then subjected to final heat
treatment at 300.degree. C. for 10 min.
Example 5
While nitrogen was passed through a 1 L reactor equipped with a
stirrer, a nitrogen injector, a dropping funnel, a temperature
controller and a condenser, 719 g of N,N-dimethylacetamide (DMAc)
was added into the reactor, the temperature of the reactor was set
to 25.degree. C., 57.64 g (0.18 mol) of TFDB was dissolved, and the
resultant solution was maintained at 25.degree. C. Further, 23.99 g
(0.054 mol) of 6FDA and 7.57 g (0.036 mol) of CPDA were added and
stirred for a predetermined period of time and thus dissolved and
allowed to react. The temperature of the solution was then
maintained at 15.degree. C., after which 18.27 g (0.09 mol) of TPC
was added and allowed to react at 25.degree. C. for 12 hr, thus
obtaining a polyamic acid solution having a solid content of 13 wt
% and a viscosity of 790 poise.
The polyamic acid solution was added with 34.17 g of pyridine and
44.12 g of acetic anhydride, stirred for 30 min, 40 further stirred
at 70.degree. C. for 1 hr, cooled to room temperature, and
precipitated with 20 L of methanol, after which the precipitated
solid was filtered, ground and then dried at 100.degree. C. for 6
hr in a vacuum, yielding 90 g of a polyamide-imide copolymer in
solid powder form.
The polyamide-imide solid powder was found to have an average
particle size of 70 to 80 .mu.m through particle size measurement
and a weight average molecular weight of 151,000 through molecular
weight measurement.
90 g of the polyamide-imide copolymer in solid powder form was
dissolved in 728 g of DMAc, thus obtaining an 11 wt % solution. The
solution thus obtained was applied onto a stainless plate, cast to
100 .mu.m, dried using hot air at 150.degree. C. for 1 hr, at
200.degree. C. for 1 hr, and at 300.degree. C. for 30 min, and then
slowly cooled, after which the resulting film was separated from
the stainless plate, thus obtaining an 11 .mu.m thick
polyamide-imide film, which was then subjected to final heat
treatment at 300.degree. C. for 10 min.
The polyamide-imide film thus obtained was measured to determine
the coefficient of linear thermal expansion at 50 to 300.degree. C.
using a TMA method. As a result, the coefficient of linear thermal
expansion thereof was found to be 10.2 ppm/.degree. C.
Example 6
While nitrogen was passed through a 1 L reactor equipped with a
stirrer, a nitrogen injector, a dropping funnel, a temperature
controller and a condenser, 764 g of N,N-dimethylacetamide (DMAc)
was added into the reactor, the temperature of the reactor was set
to 25.degree. C., 57.64 g (0.18 mol) of TFDB was dissolved, and the
resultant solution was maintained at 25.degree. C. Further, 31.99 g
(0.072 mol) of 6FDA and 7.57 g (0.036 mol) of CPDA were added and
stirred for a predetermined period of time and thus dissolved and
allowed to react. The temperature of the solution was then
maintained at 15.degree. C., after which 14.62 g (0.072 mol) of TPC
was added and allowed to react at 25.degree. C. for 12 hr, thus
obtaining a polyamic acid solution having a solid content of 13 wt
% and a viscosity of 780 poise.
The polyamic acid solution was added with 34.17 g of pyridine and
44.12 g of acetic anhydride, stirred for 30 min, further stirred at
70.degree. C. for 1 hr, cooled to room temperature, and
precipitated with 20 L of methanol, after which the precipitated
solid was filtered, ground and then dried at 100.degree. C. for 6
hr in a vacuum, yielding 102 g of a polyamide-imide copolymer in
solid powder form.
The polyamide-imide solid powder was found to have an average
particle size of 70 to 80 .mu.m through particle size measurement
and a weight average molecular weight of 150,000 through molecular
weight measurement.
102 g of the polyamide-imide copolymer in solid powder form was
dissolved in 825 g of DMAc, thus obtaining an 11 wt % solution. The
solution thus obtained was applied onto a stainless plate, cast to
100 .mu.m, dried using hot air at 150.degree. C. for 1 hr, at
200.degree. C. for 1 hr, and at 300.degree. C. for 30 min, and then
slowly cooled, after which the resulting film was separated from
the stainless plate, thus obtaining a 12 .mu.m thick
polyamide-imide film, which was then subjected to final heat
treatment at 300.degree. C. for 10 min.
Example 7
While nitrogen was passed through a 1 L reactor equipped with a
stirrer, a nitrogen injector, a dropping funnel, a temperature
controller and a condenser, 806 g of N,N-dimethylacetamide (DMAc)
was added into the reactor, the temperature of the reactor was set
to 25.degree. C., 57.64 g (0.18 mol) of TFDB was dissolved, and the
resultant solution was maintained at 25.degree. C. Further, 47.98 g
(0.108 mol) of 6FDA and 7.57 g (0.036 mol) of CPDA were added and
stirred for a predetermined period of time and thus dissolved and
allowed to react. The temperature of the solution was then
maintained at 15.degree. C., after which 7.31 g (0.036 mol) of TPC
was added and allowed to react at 25.degree. C. for 12 hr, thus
obtaining a polyamic acid solution having a solid content of 13 wt
% and a viscosity of 790 poise.
The polyamic acid solution was added with 34.17 g of pyridine and
44.12 g of acetic anhydride, stirred for 30 min, further stirred at
70.degree. C. for 1 hr, cooled to room temperature, and
precipitated with 20 L of methanol, after which the precipitated
solid was filtered, ground and then dried at 100.degree. C. for 6
hr in a vacuum, yielding 109 g of a polyamide-imide copolymer in
solid powder form.
The polyamide-imide solid powder was found to have an average
particle size of 70 to 80 .mu.m through particle size measurement
and a weight average molecular weight of 151,000 through molecular
weight measurement.
109 g of the polyamide-imide copolymer in solid powder form was
dissolved in 882 g of DMAc, thus obtaining an 11 wt % solution. The
solution thus obtained was applied onto a stainless plate, cast to
100 .mu.m, dried using hot air at 150.degree. C. for 1 hr, at
200.degree. C. for 1 hr, and at 300.degree. C. for 30 min, and then
slowly cooled, after which the resulting film was separated from
the stainless plate, thus obtaining a 10 .mu.m thick
polyamide-imide film, which was then subjected to final heat
treatment at 300.degree. C. for 10 min.
Example 8
While nitrogen was passed through a 1 L reactor equipped with a
stirrer, a nitrogen injector, a dropping funnel, a temperature
controller and a condenser, 849 g of N,N-dimethylacetamide (DMAc)
was added into the reactor, the temperature of the reactor was set
to 25.degree. C., 57.64 g (0.18 mol) of TFDB was dissolved, and the
resultant solution was maintained at 25.degree. C. Further, 59.97 g
(0.135 mol) of 6FDA and 7.57 g (0.036 mol) of CPDA were added and
stirred for a predetermined period of time and thus dissolved and
allowed to react. The temperature of the solution was then
maintained at 15.degree. C., after which 1.83 g (0.009 mol) of TPC
was added and allowed to react at 25.degree. C. for 12 hr, thus
obtaining a polyamic acid solution having a solid content of 13 wt
% and a viscosity of 815 poise.
The polyamic acid solution was added with 34.17 g of pyridine and
44.12 g of acetic anhydride, stirred for 30 min, further stirred at
70.degree. C. for 1 hr, cooled to room temperature, and
precipitated with 20 L of methanol, after which the precipitated
solid was filtered, ground and then dried at 100.degree. C. for 6
hr in a vacuum, yielding 112 g of a polyamide-imide copolymer in
solid powder form.
The polyamide-imide solid powder was found to have an average
particle size of 70 to 80 .mu.m through particle size measurement
and a weight average molecular weight of 165,000 through molecular
weight measurement.
112 g of the polyamide-imide copolymer in solid powder form was
dissolved in 906 g of DMAc, thus obtaining an 11 wt % solution. The
solution thus obtained was applied onto a stainless plate, cast to
100 .mu.m, dried using hot air at 150.degree. C. for 1 hr, at
200.degree. C. for 1 hr, and at 300.degree. C. for 30 min, and then
slowly cooled, after which the resulting film was separated from
the stainless plate, thus obtaining an 11 .mu.m thick
polyamide-imide film, which was then subjected to final heat
treatment at 300.degree. C. for 10 min.
Comparative Example 1
While nitrogen was passed through a 1 L reactor equipped with a
stirrer, a nitrogen injector, a dropping funnel, a temperature
controller and a condenser, 701 g of N,N-dimethylacetamide (DMAc)
was added into the reactor, the temperature of the reactor was set
to 25.degree. C., 57.64 g (0.18 mol) of TFDB was dissolved, and the
resultant solution was maintained at 25.degree. C. Further, 19.99 g
(0.045 mol) of 6FDA and 7.06 g (0.036 mol) of CBDA were added and
stirred for a predetermined period of time and thus dissolved and
allowed to react. The temperature of the solution was then
maintained at 15.degree. C., after which 20.10 g (0.099 mol) of TPC
was added and allowed to react at 25.degree. C. for 12 hr, thus
obtaining a polyamic acid solution having a solid content of 13 wt
% and a viscosity of 870 poise.
The polyamic acid solution was added with 34.17 g of pyridine and
44.12 g of acetic anhydride, stirred for 30 min, further stirred at
70.degree. C. for 1 hr, cooled to room temperature, and
precipitated with 20 L of methanol, after which the precipitated
solid was filtered, ground and then dried at 100.degree. C. for 6
hr in a vacuum, yielding 93 g of a polyamide-imide copolymer in
solid powder form.
The polyamide-imide solid powder was found to have an average
particle size of 70 to 80 .mu.m through particle size measurement
and a weight average molecular weight of 178,000 through molecular
weight measurement.
93 g of the polyamide-imide copolymer in solid powder form was
dissolved in 752 g of DMAc, thus obtaining an 11 wt % solution. The
solution thus obtained was applied onto a stainless plate, cast to
100 .mu.m, dried using hot air at 150.degree. C. for 1 hr, at
200.degree. C. for 1 hr, and at 300.degree. C. for 30 min, and then
slowly cooled, after which the resulting film was separated from
the stainless plate, thus obtaining an 11 .mu.m thick
polyamide-imide film, which was then subjected to final heat
treatment at 300.degree. C. for 10 min.
Comparative Example 2
While nitrogen was passed through a 1 L reactor equipped with a
stirrer, a nitrogen injector, a dropping funnel, a temperature
controller and a condenser, 725 g of N,N-dimethylacetamide (DMAc)
was added into the reactor, the temperature of the reactor was set
to 25.degree. C., 57.64 g (0.18 mol) of TFDB was dissolved, and the
resultant solution was maintained at 25.degree. C. Further, 19.99 g
(0.045 mol) of 6FDA and 10.59 g (0.036 mol) of BPDA were added and
stirred for a predetermined period of time and thus dissolved and
allowed to react. The temperature of the solution was then
maintained at 15.degree. C., after which 20.10 g (0.099 mol) of TPC
was added and allowed to react at 25.degree. C. for 12 hr, thus
obtaining a polyamic acid solution having a solid content of 13 wt
% and a viscosity of 855 poise.
The polyamic acid solution was added with 34.17 g of pyridine and
44.12 g of acetic anhydride, stirred for 30 min, further stirred at
70.degree. C. for 1 hr, cooled to room temperature, and
precipitated with 20 L of methanol, after which the precipitated
solid was filtered, ground and then dried at 100.degree. C. for 6
hr in a vacuum, yielding 94 g of a polyamide-imide copolymer in
solid powder form.
The polyamide-imide solid powder was found to have an average
particle size of 70 to 80 .mu.m through particle size measurement
and a weight average molecular weight of 170,000 through molecular
weight measurement.
94 g of the polyamide-imide copolymer in solid powder form was
dissolved in 760 g of DMAc, thus obtaining an 11 wt % solution. The
solution thus obtained was applied onto a stainless plate, cast to
100 .mu.m, dried using hot air at 150.degree. C. for 1 hr, at
200.degree. C. for 1 hr, and at 300.degree. C. for 30 min, and then
slowly cooled, after which the resulting film was separated from
the stainless plate, thus obtaining a 10 .mu.m thick
polyamide-imide film, which was then subjected to final heat
treatment at 300.degree. C. for 10 min.
Comparative Example 3
While nitrogen was passed through a 1 L reactor equipped with a
stirrer, a nitrogen injector, a dropping funnel, a temperature
controller and a condenser, 861 g of N,N-dimethylacetamide (DMAc)
was added into the reactor, the temperature of the reactor was set
to 25.degree. C., 57.64 g (0.18 mol) of TFDB was dissolved, and the
resultant solution was maintained at 25.degree. C. Further, 63.97 g
(0.144 mol) of 6FDA and 7.06 g (0.036 mol) of CBDA were added and
stirred for a predetermined period of time and thus dissolved and
allowed to react at 25.degree. C. for 12 hr, thus obtaining a
polyamic acid solution having a solid content of 13 wt % and a
viscosity of 800 poise.
The polyamic acid solution was added with 34.17 g of pyridine and
44.12 g of acetic anhydride, stirred for 30 min, further stirred at
70.degree. C. for 1 hr, cooled to room temperature, and
precipitated with 20 L of methanol, after which the precipitated
solid was filtered, ground and then dried at 100.degree. C. for 6
hr in a vacuum, yielding 118 g of a polyamide-imide copolymer in
solid powder form.
The polyamide-imide solid powder was found to have an average
particle size of 70 to 80 .mu.m through particle size measurement
and a weight average molecular weight of 162,000 through molecular
weight measurement.
118 g of the polyamide-imide copolymer in solid powder form was
dissolved in 954 g of DMAc, thus obtaining an 11 wt % solution. The
solution thus obtained was applied onto a stainless plate, cast to
100 .mu.m, dried using hot air at 150.degree. C. for 1 hr, at
200.degree. C. for 1 hr, and at 300.degree. C. for 30 min, and then
slowly cooled, after which the resulting film was separated from
the stainless plate, thus obtaining a 10 82 m thick polyamide-imide
film, which was then subjected to final heat treatment at
300.degree. C. for 10 min.
Comparative Example 4
While nitrogen was passed through a 1 L reactor equipped with a
stirrer, a nitrogen injector, a dropping funnel, a temperature
controller and a condenser, 864 g of N,N-dimethylacetamide (DMAc)
was added into the reactor, the temperature of the reactor was set
to 25.degree. C., 57.64 g (0.18 mol) of TFDB was dissolved, and the
resultant solution was maintained at 25.degree. C. Further, 63.97 g
(0.144 mol) of 6FDA and 7.57 g (0.036 mol) of CPDA were added and
stirred for a predetermined period of time and thus dissolved and
allowed to react at 25.degree. C. for 12 hr, thus obtaining a
polyamic acid solution having a solid content of 13 wt % and a
viscosity of 720 poise.
The polyamic acid solution was added with 34.17 g of pyridine and
44.12 g of acetic anhydride, stirred for 30 min, further stirred at
70.degree. C. for 1 hr, cooled to room temperature, and
precipitated with 20 L of methanol, after which the precipitated
solid was filtered, ground and then dried at 100.degree. C. for 6
hr in a vacuum, yielding 116 g of a polyamide-imide copolymer in
solid powder form.
The polyamide-imide solid powder was found to have an average
particle size of 70 to 80 .mu.m through particle size measurement
and a weight average molecular weight of 150,000 through molecular
weight measurement.
116 g of the polyamide-imide copolymer in solid powder form was
dissolved in 938 g of DMAc, thus obtaining an 11 wt % solution. The
solution thus obtained was applied onto a stainless plate, cast to
100 .mu.m, dried using hot air at 150.degree. C. for 1 hr, at
200.degree. C. for 1 hr, and at 300.degree. C. for 30 min, and then
slowly cooled, after which the resulting film was separated from
the stainless plate, thus obtaining an 11 .mu.m thick
polyamide-imide film, which was then subjected to final heat
treatment at 300.degree. C. for 10 min.
<Evaluation of Properties>
(1) Transmittance
The transmittance of the film of each of Examples and Comparative
Examples was measured at 550 nm using a UV spectrophotometer
(CM-3700d, made by Konica Minolta).
(2) Yellow Index (Y.I.)
The yellow index was measured at 550 nm using a UV
spectrophotometer (CM-3700d, made by Konica Minolta) according to
ASTM E313.
(3) CTE (Coefficient of Thermal Expansion)
The CTE was measured at 50 to 300.degree. C. using TMA (Diamond
TMA, made by Perkin Elmer) through a TMA method, and the heating
rate was 10.degree. C./min and a load of 100 mN was applied.
(4) Measurement of Thickness
Five random points on the polyamide-imide film were selected, and
the thickness thereof was measured using an Anritsu electronic
micrometer having an error of .+-.0.5% or less.
(5) Birefringence
Birefringence was measured three times at 630 nm using a prism
coupler (Sairon SPA4000), and the average value thereof was
determined.
(6) Tensile Strength
Tensile strength was measured using 5967 made by Instron according
to ASTM-D882. A test sample had a size of 13 mm.times.100 mm, and
the tensile strength thereof was measured 7 times under conditions
of a load cell of 1 KN and a tension rate of 50 mm/min, and the
average value thereof, rather than the maximum value and the
minimum value, was determined.
(7) Retardation
Retardation was measured using a RETS made by OTSUKA ELECTRONICS. A
test sample, having a square shape with a width and length of 1
inch, was mounted to a sample holder and fixed at 550 nm using a
monochromator, and Ro (in-plane retardation) was measured at an
incident angle of 0.degree. and Rth (thickness-direction
retardation) was measured at an incident angle of 45.degree..
Ro=(nx-ny)*d 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 .mu.m.
TABLE-US-00001 TABLE 1 Tensile Thick. Transmit CTE Bire- strength
Retardation Composition Molar ratio (.mu.m) (%) Y.I. (ppm/.degree.
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.
* * * * *