U.S. patent application number 16/262472 was filed with the patent office on 2019-08-01 for polyamide-imide film and preparation method thereof.
The applicant listed for this patent is SKC CO., LTD.. Invention is credited to Dawoo JEONG, Sunhwan KIM, Jin Woo LEE, Dong Jin LIM, Dae Seong OH.
Application Number | 20190233590 16/262472 |
Document ID | / |
Family ID | 65493793 |
Filed Date | 2019-08-01 |
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United States Patent
Application |
20190233590 |
Kind Code |
A1 |
JEONG; Dawoo ; et
al. |
August 1, 2019 |
POLYAMIDE-IMIDE FILM AND PREPARATION METHOD THEREOF
Abstract
Embodiments relate to a polyamide-imide film that secures
excellent tensile toughness and elastic restoring force, and a
process for preparing the same. The polyamide-imide film comprises
a polyamide-imide polymer formed by polymerizing a diamine
compound, a dianhydride compound, and a dicarbonyl compound,
wherein the area value up to the yield point derived by the 0.2%
off-set method on a stress-strain curve of the polyamide-imide film
as measured using a universal testing machine (UTM) is 80 to 150
J/m.sup.2.
Inventors: |
JEONG; Dawoo; (Gyeonggi-do,
KR) ; KIM; Sunhwan; (Incheon, KR) ; OH; Dae
Seong; (Seoul, KR) ; LEE; Jin Woo;
(Gyeonggi-do, KR) ; LIM; Dong Jin; (Gyeonggi-do,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SKC CO., LTD. |
Gyeonggi-do |
|
KR |
|
|
Family ID: |
65493793 |
Appl. No.: |
16/262472 |
Filed: |
January 30, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29K 2079/085 20130101;
B29C 39/38 20130101; B29L 2007/008 20130101; C08J 5/18 20130101;
C08G 73/1032 20130101; C08J 2379/08 20130101; C08G 73/14 20130101;
B29C 39/14 20130101; B29C 39/003 20130101 |
International
Class: |
C08G 73/14 20060101
C08G073/14; C08G 73/10 20060101 C08G073/10; C08J 5/18 20060101
C08J005/18; B29C 39/00 20060101 B29C039/00; B29C 39/14 20060101
B29C039/14; B29C 39/38 20060101 B29C039/38 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 31, 2018 |
KR |
10-2018-0011753 |
Claims
1. A polyamide-imide film, which comprises: a polyamide-imide
polymer formed by polymerizing a diamine compound, a dianhydride
compound, and a dicarbonyl compound, wherein the area value up to
the yield point derived by the 0.2% off-set method on a
stress-strain curve of the polyamide-imide film as measured using a
universal testing machine (UTM) is 80 to 150 J/m.sup.2.
2. The polyamide-imide film of claim 1, wherein the area value is
100 to 140 J/m.sup.2.
3. The polyamide-imide film of claim 1, which has a modulus of 5.0
GPa or more based on a thickness of 50 .mu.m.
4. The polyamide-imide film of claim 1, which has a surface
hardness of HB or higher.
5. The polyamide-imide film of claim 1, which has a yellow index
(YI) of 5 or less based on a thickness of 50 .mu.m.
6. The polyamide-imide film of claim 1, which has a haze of 2% or
less based on a thickness of 50 .mu.m.
7. The polyamide-imide film of claim 1, which has a light
transmittance measured at 550 nm of 85% or more based on a
thickness of 50 .mu.m.
8. The polyamide-imide film of claim 1, wherein the polyamide-imide
film has a restoration angle of 60.degree. or more at the time of
evaluating the folding restoring force, and the restoration angle
at the time of evaluating the folding restoring force refers to the
angle at which the film bent and inserted between zigs of a 5 mm
interval is restored after 24 hours under the conditions of
85.degree. C. and 85% RH.
9. The polyamide-imide film of claim 1, wherein the diamine
compound is represented by the following Formula 1, the dianhydride
compound is represented by the following Formula 2, and the
dicarbonyl compound is represented by the following Formula 3:
##STR00020## in the above Formulae 1 to 3, E and J are each
independently selected from a substituted or unsubstituted divalent
C.sub.6-C.sub.30 aliphatic cyclic group, a substituted or
unsubstituted divalent C.sub.4-C.sub.30 heteroaliphatic cyclic
group, a substituted or unsubstituted divalent C.sub.6-C.sub.30
aromatic cyclic group, a substituted or unsubstituted divalent
C.sub.4-C.sub.30 heteroaromatic cyclic group, a substituted or
unsubstituted C.sub.1-C.sub.30 alkylene group, a substituted or
unsubstituted C.sub.2-C.sub.30 alkenylene group, a substituted or
unsubstituted C.sub.2-C.sub.30 alkynylene group, --O--, --S--,
--C(.dbd.O)--, --CH(OH)--, --S(.dbd.O).sub.2--,
--Si(CH.sub.3).sub.2--, --C(CH.sub.3).sub.2--, and
--C(CF.sub.3).sub.2--, e and j are each independently selected from
integers of 1 to 5, when e is 2 or more, then the 2 or more E are
the same as, or different from, each other, when j is 2 or more,
then the 2 or more J are the same as, or different from, each
other, G is bonded by a bonding group selected from a substituted
or unsubstituted tetravalent C.sub.6-C.sub.30 aliphatic cyclic
group, a substituted or unsubstituted tetravalent C.sub.4-C.sub.30
heteroaliphatic cyclic group, a substituted or unsubstituted
tetravalent C.sub.6-C.sub.30 aromatic cyclic group, a substituted
or unsubstituted tetravalent C.sub.4-C.sub.30 heteroaromatic cyclic
group, wherein the aliphatic cyclic group, the heteroaliphatic
cyclic group, the aromatic cyclic group, or the heteroaromatic
cyclic group may be present alone or may be bonded to each other to
form a condensed ring, a substituted or unsubstituted
C.sub.1-C.sub.30 alkylene group, a substituted or unsubstituted
C.sub.2-C.sub.30 alkenylene group, a substituted or unsubstituted
C.sub.2-C.sub.30 alkynylene group, --O--, --S--, --C(.dbd.O)--,
--CH(OH)--, --S(.dbd.O).sub.2--, --Si(CH.sub.3).sub.2--,
--C(CH.sub.3).sub.2--, and --C(CF.sub.3).sub.2--, and X is a
halogen atom.
10. The polyamide-imide film of claim 1, wherein the dianhydride
compound is composed of a compound having a fluorine-containing
substituent.
11. The polyamide-imide film of claim 1, wherein the dicarbonyl
compound comprises at least two dicarbonyl compounds different from
each other.
12. The polyamide-imide film of claim 1, wherein the
polyamide-imide polymer comprises a repeat unit represented by the
following Formula A and a repeat unit represented by the following
Formula B: ##STR00021## in the above Formulae A and B, E and J are
each independently selected from a substituted or unsubstituted
divalent C.sub.6-C.sub.30 aliphatic cyclic group, a substituted or
unsubstituted divalent C.sub.4-C.sub.30 heteroaliphatic cyclic
group, a substituted or unsubstituted divalent C.sub.6-C.sub.30
aromatic cyclic group, a substituted or unsubstituted divalent
C.sub.4-C.sub.30 heteroaromatic cyclic group, a substituted or
unsubstituted C.sub.1-C.sub.30 alkylene group, a substituted or
unsubstituted C.sub.2-C.sub.30 alkenylene group, a substituted or
unsubstituted C.sub.2-C.sub.30 alkynylene group, --O--, --S--,
--C(.dbd.O)--, --CH(OH)--, --S(.dbd.O).sub.2--,
--Si(CH.sub.3).sub.2--, --C(CH.sub.3).sub.2--, and
--C(CF.sub.3).sub.2--, e and j are each independently selected from
integers of 1 to 5, when e is 2 or more, then the 2 or more E are
the same as, or different from, each other, when j is 2 or more,
then the 2 or more J are the same as, or different from, each
other, and G is bonded by a bonding group selected from a
substituted or unsubstituted tetravalent C.sub.6-C.sub.30 aliphatic
cyclic group, a substituted or unsubstituted tetravalent
C.sub.4-C.sub.30 heteroaliphatic cyclic group, a substituted or
unsubstituted tetravalent C.sub.6-C.sub.30 aromatic cyclic group, a
substituted or unsubstituted tetravalent C.sub.4-C.sub.30
heteroaromatic cyclic group, wherein the aliphatic cyclic group,
the heteroaliphatic cyclic group, the aromatic cyclic group, or the
heteroaromatic cyclic group may be present alone or may be bonded
to each other to form a condensed ring, a substituted or
unsubstituted C.sub.1-C.sub.30 alkylene group, a substituted or
unsubstituted C.sub.2-C.sub.30 alkenylene group, a substituted or
unsubstituted C.sub.2-C.sub.30 alkynylene group, --O--, --S--,
--C(.dbd.O)--, --CH(OH)--, --S(.dbd.O).sub.2--,
--Si(CH.sub.3).sub.2--, --C(CH.sub.3).sub.2--, and
--C(CF.sub.3).sub.2--.
13. A process for preparing a polyamide-imide film, which
comprises: simultaneously or sequentially mixing and reacting a
diamine compound, a dianhydride compound, and a dicarbonyl compound
in an organic solvent in a polymerization apparatus to prepare a
polymer solution; transferring the polymer solution to a tank;
casting the polymer solution in the tank and then drying it to
prepare a gel-sheet; thermally treating the gel-sheet, while it is
moved on a belt, to prepare a cured film; and winding the cured
film using a winder, wherein the ratio of the moving speed of the
gel-sheet on the belt at the time of thermal treatment to the
moving speed of the cured film at the time of winding is 1:0.95 to
1:1.40.
14. The process for preparing a polyamide-imide film of claim 13,
wherein the step of preparing the polymer solution may comprise:
(a) simultaneously or sequentially mixing and reacting a diamine
compound, a dianhydride compound, and a dicarbonyl compound in an
organic solvent in a polymerization apparatus to prepare a first
polymer solution; (b) measuring the viscosity of the first polymer
solution and evaluating whether the target viscosity is reached;
and (c) if the viscosity of the first polymer solution does not
reach the target viscosity, further adding the dicarbonyl compound
to prepare a second polymer solution having the target
viscosity.
15. The process for preparing a polyamide-imide film of claim 14,
wherein the target viscosity at room temperature is 100,000 cps to
300,000 cps.
16. The process for preparing a polyamide-imide film of claim 13,
wherein, once the polymer solution is prepared, the step of
transferring the polymer solution to the tank is carried out
without any additional steps.
17. The process for preparing a polyamide-imide film of claim 13,
wherein the temperature inside the tank is -20.degree. C. to
0.degree. C.
18. The process for preparing a polyamide-imide film of claim 13,
which, after the polymer solution is transferred to the tank,
further comprises carrying out vacuum degassing; and purging the
tank with an inert gas.
19. The process for preparing a polyamide-imide film of claim 13,
which, after the polymer solution is transferred to the tank,
further comprise storing the polymer solution in the tank for 12
hours to 60 hours.
20. The process for preparing a polyamide-imide film of claim 13,
wherein the polymer solution is cast and then dried at a
temperature of 60.degree. C. to 150.degree. C. for 5 minutes to 60
minutes to prepare a gel-sheet.
21. The process for preparing a polyamide-imide film of claim 13,
wherein the thermal treatment is carried out in a temperature range
of 80.degree. C. to 500.degree. C. at a temperature elevation rate
of 2.degree. C./min to 80.degree. C./min for 5 to 40 minutes.
22. The process for preparing a polyamide-imide film of claim 13,
which, after the cured film is prepared by thermal treatment,
further comprises cooling the cured film while it is moved on a
belt.
23. The process for preparing a polyamide-imide film of claim 13,
wherein the ratio of the moving speed of the gel-sheet on the belt
at the time of thermal treatment to the moving speed of the cured
film at the time of winding is 1:0.99 to 1:1.10.
24. The process for preparing a polyamide-imide film of claim 13,
wherein the area value up to the yield point derived by the 0.2%
off-set method on a stress-strain curve of the polyamide-imide film
as measured using a universal testing machine (UTM) is 80 to 150
J/m.sup.2.
25. The process for preparing a polyamide-imide film of claim 13,
wherein the polyamide-imide film has a modulus of 5.0 GPa or more
based on a thickness of 50 .mu.m.
26. The process for preparing a polyamide-imide film of claim 13,
wherein the polyamide-imide film has a restoration angle of
60.degree. or more at the time of evaluating the folding restoring
force, and the restoration angle at the time of evaluating the
folding restoring force refers to the angle at which the film bent
and inserted between zigs of a 5 mm interval is restored after 24
hours under the conditions of 85.degree. C. and 85% RH.
Description
TECHNICAL FIELD
[0001] Embodiments relate to a polyamide-imide film that is
excellent in mechanical properties and optical properties and that
especially secures excellent tensile toughness and elastic
restoring force, and a process for preparing the same.
BACKGROUND ART OF THE INVENTION
[0002] Since polyamide-imide (PAI) is excellent in resistance to
friction, heat, and chemicals, it is employed in such applications
as primary electrical insulation, coatings, adhesives, resins for
extrusion, heat-resistant paintings, heat-resistant boards,
heat-resistant adhesives, heat-resistant fibers, heat-resistant
films, and the like.
[0003] Polyamide-imide is used in various fields. For example,
polyamide-imide is made in the form of a powder and used as a
coating for a metal or a magnetic wire. It is mixed with other
additives depending on the application thereof. In addition,
polyamide-imide is used together with a fluoropolymer as a painter
for decoration and corrosion prevention. It also plays a role of
bonding a fluoropolymer to a metal substrate. In addition,
polyamide-imide is used to coat kitchenware, used as a membrane for
gas separation by virtue of its heat resistance and chemical
resistance, and used in natural gas wells for filtration of such
contaminants as carbon dioxide, hydrogen sulfide, and
impurities.
[0004] In recent years, polyamide-imide has been developed in the
form of a film, which is less expensive and has excellent optical,
mechanical, and thermal characteristics.
DISCLOSURE OF THE INVENTION
Problem to be Solved
[0005] An embodiment aims to provide a polyamide-imide film that is
excellent in mechanical properties and optical properties and that
especially secures excellent tensile toughness and elastic
restoring force.
[0006] In addition, another embodiment aims to provide a process
for preparing a polyamide-imide film that secures excellent tensile
toughness and elastic restoring force.
Solution to the Problem
[0007] The polyamide-imide film according to an embodiment
comprises a polyamide-imide polymer formed by polymerizing a
diamine compound, a dianhydride compound, and a dicarbonyl
compound, wherein the area value up to the yield point derived by
the 0.2% off-set method on a stress-strain curve of the
polyamide-imide film as measured using a universal testing machine
(UTM) is 80 to 150 J/m.sup.2.
[0008] The process for preparing a polyamide-imide film according
to another embodiment comprises simultaneously or sequentially
mixing and reacting a diamine compound, a dianhydride compound, and
a dicarbonyl compound in an organic solvent in a polymerization
apparatus to prepare a polymer solution; transferring the polymer
solution to a tank; casting the polymer solution in the tank and
then drying it to prepare a gel-sheet; thermally treating the
gel-sheet, while it is moved on a belt, to prepare a cured film;
and winding the cured film using a winder, wherein the ratio of the
moving speed of the gel-sheet on the belt at the time of thermal
treatment to the moving speed of the cured film at the time of
winding is 1:0.95 to 1:1.40.
Advantageous Effects of the Invention
[0009] The polyamide-imide film according to the embodiments is
excellent in mechanical properties and optical properties and is
especially capable of securing excellent tensile toughness and
elastic restoring force.
[0010] The process for preparing a polyamide-imide film according
to the embodiments is capable of providing a polyamide-imide film
that secures excellent tensile toughness and elastic restoring
force.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 shows a stress-strain curve of the polyamide-imide
film according to Example 1.
[0012] FIG. 2 shows a stress-strain curve of the polyamide-imide
film according to Example 2.
[0013] FIG. 3 shows a stress-strain curve of the polyamide-imide
film according to Example 3.
[0014] FIG. 4 shows a stress-strain curve of the polyamide-imide
film according to Comparative Example 1.
[0015] FIG. 5 shows a stress-strain curve of the polyamide-imide
film according to Comparative Example 2.
[0016] FIG. 6 shows a stress-strain curve of the polyamide-imide
film according to Comparative Example 3.
[0017] FIG. 7 schematically illustrates a process facility for
preparing a polyamide-imide film according to an embodiment.
DETAILED DESCRIPTION FOR CARRYING OUT THE INVENTION
[0018] Hereinafter, the present invention is described in detail
with reference to embodiments. The embodiments are not limited to
those disclosed below. Rather, they may be modified into various
forms as long as the gist of the invention is not altered.
[0019] In order to clearly illustrate the various layers and
regions in the drawings, some regions or some thicknesses are
enlarged. In the drawings, for the convenience of explanation, the
thicknesses of some layers and regions are exaggerated. Same
reference numerals refer to the same elements throughout the
specification.
[0020] In this specification, when a part is referred to as
"comprising" an element, it is to be understood that the part may
comprise other elements as well, unless otherwise indicated.
[0021] In addition, all numbers and expression related to the
quantities of components, reaction conditions, and the like used
herein are to be understood as being modified by the term "about,"
unless otherwise indicated.
[0022] The terms first, second, and the like are used herein to
describe various elements, and the elements should not be limited
by the terms. The terms are used only for the purpose of
distinguishing one element from another.
[0023] In addition, the term "substituted" as used herein means to
be substituted with at least one substituent group selected from
the group consisting of deuterium, --F, --Cl, --Br, --I, a hydroxyl
group, a cyano group, a nitro group, an amino group, an amidino
group, a hydrazine group, a hydrazone group, an ester group, a
ketone group, a carboxyl group, a substituted or unsubstituted
alkyl group, a substituted or unsubstituted alkenyl group, a
substituted or unsubstituted alkynyl group, a substituted or
unsubstituted alkoxy group, a substituted or unsubstituted
alicyclic organic group, a substituted or unsubstituted
heterocyclic group, a substituted or unsubstituted aryl group, and
a substituted or unsubstituted heteroaryl group. The substituent
groups enumerated above may be connected to each other to form a
ring.
[0024] <Polyamide-Imide Film>
[0025] An embodiment provides a polyamide-imide film that is
excellent in mechanical properties and optical properties and that
especially secures excellent tensile toughness and elastic
restoring force.
[0026] The polyamide-imide film according to an embodiment
comprises a polyamide-imide polymer formed by polymerizing a
diamine compound, a dianhydride compound, and a dicarbonyl
compound.
[0027] The polyamide-imide polymer comprises an imide repeat unit
derived from the polymerization of the diamine compound and the
dianhydride compound and amide repeat units derived from the
polymerization of the diamine compound and the dicarbonyl
compound.
[0028] The diamine compound is a compound that forms an imide bond
with the dianhydride compound and forms an amide bond with the
dicarbonyl compound, to thereby form a copolymer.
[0029] The diamine compound is not particularly limited, but it may
be, for example, an aromatic diamine compound that contains an
aromatic structure. For example, the diamine compound may be a
compound represented by the following Formula 1.
H.sub.2N-(E).sub.e-NH.sub.2 [Formula 1]
[0030] In the above Formula 1,
[0031] E may be selected from a substituted or unsubstituted
divalent C.sub.6-C.sub.30 aliphatic cyclic group, a substituted or
unsubstituted divalent C.sub.4-C.sub.30 heteroaliphatic cyclic
group, a substituted or unsubstituted divalent C.sub.6-C.sub.30
aromatic cyclic group, a substituted or unsubstituted divalent
C.sub.4-C.sub.30 heteroaromatic cyclic group, a substituted or
unsubstituted C.sub.1-C.sub.30 alkylene group, a substituted or
unsubstituted C.sub.2-C.sub.30 alkenylene group, a substituted or
unsubstituted C.sub.2-C.sub.30 alkynylene group, --O--, --S--,
--C(.dbd.O)--, --CH(OH)--, --S(.dbd.O).sub.2--,
--Si(CH.sub.3).sub.2--, --C(CH.sub.3).sub.2--, and
--C(CF.sub.3).sub.2--.
[0032] e is selected from integers of 1 to 5. When e is 2 or more,
E may be the same as, or different from, each other.
[0033] (E).sub.e in the above Formula 1 may be selected from the
groups represented by the following Formulae 1-1a to 1-14a.
##STR00001## ##STR00002##
[0034] Specifically, (E).sub.e in the above Formula 1 may be
selected from the groups represented by the following Formulae 1-1b
to 1-13b, but it is not limited thereto.
##STR00003## ##STR00004##
[0035] More specifically, (E).sub.e in the above Formula 1 may be
the group represented by the above Formula 1-6b.
[0036] In an embodiment, the dianhydride compound may comprise a
compound having a fluorine-containing substituent. Alternatively,
the dianhydride compound may be composed of a compound having a
fluorine-containing substituent. In such event, the
fluorine-containing substituent may be a fluorinated hydrocarbon
group and specifically may be a trifluoromethyl group. But it is
not limited thereto.
[0037] In another embodiment, one kind of diamine compound may be
used as the diamine compound. That is, the diamine compound may be
composed of a single component.
[0038] For example, the diamine compound may comprise
2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) represented
by the following formula, but it is not limited thereto.
##STR00005##
[0039] The dianhydride compound is a compound that has a low
birefringence value, so that it can contribute to enhancements in
the optical properties such as transmittance of the polyamide-imide
film.
[0040] The dianhydride compound is not particularly limited, but it
may be, for example, an aromatic dianhydride compound that contains
an aromatic structure. For example, the aromatic dianhydride
compound may be a compound represented by the following Formula
2.
##STR00006##
[0041] In the above Formula 2,
[0042] G is bonded by a bonding group selected from a substituted
or unsubstituted tetravalent C.sub.6-C.sub.30 aliphatic cyclic
group, a substituted or unsubstituted tetravalent C.sub.4-C.sub.30
heteroaliphatic cyclic group, a substituted or unsubstituted
tetravalent C.sub.6-C.sub.30 aromatic cyclic group, a substituted
or unsubstituted tetravalent C.sub.4-C.sub.30 heteroaromatic cyclic
group, wherein the aliphatic cyclic group, the heteroaliphatic
cyclic group, the aromatic cyclic group, or the heteroaromatic
cyclic group may be present alone or may be bonded to each other to
form a condensed ring, a substituted or unsubstituted
C.sub.1-C.sub.30 alkylene group, a substituted or unsubstituted
C.sub.2-C.sub.30 alkenylene group, a substituted or unsubstituted
C.sub.2-C.sub.30 alkynylene group, --O--, --S--, --C(.dbd.O)--,
--CH(OH)--, --S(.dbd.O).sub.2--, --Si(CH.sub.3).sub.2--,
--C(CH.sub.3).sub.2--, and --C(CF.sub.3).sub.2--.
[0043] G in the above Formula 2 may be selected from the groups
represented by the following Formulae 2-1a to 2-9a, but it is not
limited thereto.
##STR00007##
[0044] For example, G in the above Formula 2 may be the group
represented by the above Formula 2-8a.
[0045] In an embodiment, the dianhydride compound may comprise a
compound having a fluorine-containing substituent. Alternatively,
the dianhydride compound may be composed of a compound having a
fluorine-containing substituent. In such event, the
fluorine-containing substituent may be a fluorinated hydrocarbon
group and specifically may be a trifluoromethyl group. But it is
not limited thereto.
[0046] In another embodiment, the dianhydride compound may be
composed of a single component or a mixture of two components.
[0047] For example, the dianhydride compound may comprise
2,2'-bis-(3,4-dicarboxyphenyl) hexafluoropropane dianhydride
(6-FDA) represented by the following formula, but it is not limited
thereto.
##STR00008##
[0048] The diamine compound and the dianhydride compound may be
polymerized to form a polyamic acid.
[0049] Subsequently, the polyamic acid may be converted to a
polyimide through a dehydration reaction, and the polyimide
comprises an imide repeat unit.
[0050] The polyimide may form a repeat unit represented by the
following Formula A.
##STR00009##
[0051] E, G, and e in the above Formula A are as described
above.
[0052] For example, the polyimide may comprise a repeat unit
represented by the following Formula A-1, but it is not limited
thereto.
##STR00010##
[0053] In the above Formula A-1, n is an integer of 1 to 400.
[0054] The dicarbonyl compound is not particularly limited, but it
may be, for example, a compound represented by the following
Formula 3.
##STR00011##
[0055] In the above Formula 3,
[0056] J may be selected from a substituted or unsubstituted
divalent C.sub.6-C.sub.30 aliphatic cyclic group, a substituted or
unsubstituted divalent C.sub.4-C.sub.30 heteroaliphatic cyclic
group, a substituted or unsubstituted divalent C.sub.6-C.sub.30
aromatic cyclic group, a substituted or unsubstituted divalent
C.sub.4-C.sub.30 heteroaromatic cyclic group, a substituted or
unsubstituted C.sub.1-C.sub.30 alkylene group, a substituted or
unsubstituted C.sub.2-C.sub.30 alkenylene group, a substituted or
unsubstituted C.sub.2-C.sub.30 alkynylene group, --O--, --S--,
--C(.dbd.O)--, --CH(OH)--, --S(.dbd.O).sub.2--,
--Si(CH.sub.3).sub.2--, --C(CH.sub.3).sub.2--, and
--C(CF.sub.3).sub.2--.
[0057] j is selected from integers of 1 to 5. When j is 2 or more,
J may be the same as, or different from, each other.
[0058] X is a halogen atom. Specifically, X may be F, Cl, Br, I, or
the like. More specifically, X may be Cl, but it is not limited
thereto.
[0059] (J).sub.j in the above Formula 3 may be selected from the
groups represented by the following Formulae 3-1a to 3-14a, but it
is not limited thereto.
##STR00012## ##STR00013##
[0060] Specifically, (J).sub.j in the above Formula 3 may be
selected from the groups represented by the following Formulae 3-1b
to 3-8b, but it is not limited thereto.
##STR00014##
[0061] More specifically, (J).sub.j in the above Formula 3 may be
the group represented by the above Formula 3-2b or 3-3b.
[0062] In an embodiment, a mixture of at least two kinds of
dicarbonyl compounds different from each other may be used as the
dicarbonyl compound. If two or more dicarbonyl compounds are used,
at least two dicarbonyl compound in which (J).sub.j in the above
Formula 3 is selected from the groups represented by the above
Formulae 3-1b to 3-8b may be used as the dicarbonyl compound.
[0063] In another embodiment, the dicarbonyl compound may be an
aromatic dicarbonyl compound that contains an aromatic
structure.
[0064] For example, the dicarbonyl compound may comprise a first
dicarbonyl compound and/or a second dicarbonyl compound.
[0065] The first dicarbonyl compound and the second dicarbonyl
compound may be an aromatic dicarbonyl compound, respectively.
[0066] The first dicarbonyl compound and the second dicarbonyl
compound may be compounds different from each other.
[0067] For example, the first dicarbonyl compound and the second
dicarbonyl compound may be aromatic dicarbonyl compounds different
from each other, but they are not limited thereto.
[0068] If the first dicarbonyl compound and the second dicarbonyl
compound are an aromatic dicarbonyl compound, respectively, they
comprise a benzene ring. Thus, they can contribute to improvements
in the mechanical properties such as surface hardness and tensile
strength of the polyamide-imide film thus produced.
[0069] The dicarbonyl compound may comprise terephthaloyl chloride
(TPC), 1,1'-biphenyl-4,4'-dicarbonyl dichloride (BPDC), as
represented by the following formulae, or a combination thereof.
But it is not limited thereto.
##STR00015##
[0070] For example, the first dicarbonyl compound may comprise
BPDC, and the second dicarbonyl compound may comprise TPC, but they
are not limited thereto.
[0071] Specifically, if BPDC is used as the first dicarbonyl
compound and TPC is used as the second dicarbonyl compound in a
proper combination, the polyamide-imide film thus produced may have
high oxidation resistance.
[0072] The diamine compound and the dicarbonyl compound may be
polymerized to form a repeat unit represented by the following
Formula B.
##STR00016##
[0073] E, J, e, and j in the above Formula B are as described
above.
[0074] For example, the diamine compound and the dicarbonyl
compound may be polymerized to form amide repeat units represented
by the following Formulae B-1 and B-2.
##STR00017##
[0075] In the above Formula B-1, x is an integer of 1 to 400.
##STR00018##
[0076] In the above Formula B-2, y is an integer of 1 to 400.
[0077] In another embodiment, the polyamide-imide polymer may
comprise a repeat unit represented by the following Formula A and a
repeat unit represented by the following Formula B:
##STR00019##
[0078] E, G, J, e, and j in the above Formulae A and B are as
described above.
[0079] The polyamide-imide polymer comprises an imide repeat unit
and an amide repeat unit. The molar ratio of the imide repeat unit
to the amide repeat unit may be 20:80 to 80:20, for example, 20:80
to 50:50. In such event, the imide repeat unit may be a repeat unit
represented by the above Formula A, and the amide repeat unit may
be a repeat unit represented by the above Formula B.
[0080] If the molar ratio satisfies the above range, it is easy to
control the viscosity of the polymer solution by using the monomers
as described above for preparing the same. As a result, it is easy
to produce a uniform film without defects on the surface thereof
from the gel-sheet and the cured film. In addition, it is possible
to produce a film that secures excellent tensile toughness and
elastic restoring force.
[0081] In an embodiment, the area value up to the yield point
derived by the 0.2% off-set method on a stress-strain curve of the
polyamide-imide film as measured using a universal testing machine
(UTM) is 80 to 150 J/m.sup.2.
[0082] Specifically, the area value up to the yield point derived
by the 0.2% off-set method on a stress-strain curve of the
polyamide-imide film as measured using a universal testing machine
(UTM) may be 100 to 140 J/m.sup.2, 110 to 130 J/m.sup.2, or 120 to
130 J/m.sup.2, but it is not limited thereto.
[0083] The area up to the yield point refers to the area of the
elastic region, which stands for a measure of how well the material
can store energy prior to plasticization. The larger the area value
of the elastic region, the greater the resistance to plasticization
and impact failure, which indicates that the material is well
restored upon deformation.
[0084] In an embodiment, the polyamide-imide film has a modulus of
5.0 GPa or more when measured at room temperature. Specifically,
the modulus may be 5 GPa to 10 GPa, 6 GPa to 10 GPa, or 7 to 10
GPa.
[0085] In an embodiment, the polyamide-imide film has a surface
hardness of HB or higher. Specifically, the surface hardness may be
H or higher, or 2H or higher, but it is not limited thereto.
[0086] In an embodiment, the polyamide-imide film has a yellow
index of 5 or less. Specifically, the yellow index may be 4.5 or
less. More specifically, the yellow index may be 4 or less, but it
is not limited thereto.
[0087] In an embodiment, the polyamide-imide film has a haze of 2%
or less. Specifically, the haze may be 1.8% or less or 1.5% or
less. More specifically, the haze may be 1.0% or less or 0.9% or
less, but it is not limited thereto.
[0088] In an embodiment, the polyamide-imide film has a light
transmittance measured at 550 nm of 85% or more. Specifically, the
light transmittance measured at 550 nm may be 86% or more, 87% or
more, or 88% or more, but it is not limited thereto.
[0089] In an embodiment, the polyamide-imide film may have a
restoration angle of 60.degree. or more at the time of evaluating
the folding restoring force. Specifically, the restoration angle
may be 60.degree. to 180.degree., 60.degree. to 150.degree.,
60.degree. to 120.degree., 60.degree. to 90.degree., 60.degree. to
80.degree., or 60.degree. to 70.degree., but it is not limited
thereto.
[0090] The restoration angle at the time of evaluating the folding
restoring force refers to the angle at which the film bent and
inserted between zigs of a 5 mm interval is restored after 24 hours
under the conditions of 85.degree. C. and 85% RH.
[0091] In an embodiment, the polyamide-imide film has a tensile
strength of 15 kgf/mm.sup.2 or more. Specifically, the tensile
strength may be 18 kgf/mm.sup.2 or more, 20 kgf/mm.sup.2 or more,
21 kgf/mm.sup.2 or more, or 22 kgf/mm.sup.2 or more, but it is not
limited thereto.
[0092] In an embodiment, the polyamide-imide film has an elongation
of 15% or more. Specifically, the elongation may be 16% or more,
17% or more, or 17.5% or more, but it is not limited thereto.
[0093] The physical properties of the polyamide-imide film as
described above are based on a thickness of 40 .mu.m to 60 .mu.m.
For example, the physical properties of the polyamide-imide film
may be based on a thickness of 50 .mu.m.
[0094] The various characteristics of the polyamide-imide film as
described above may be combined.
[0095] The polyamide-imide film is prepared by the preparation
process as described below such that it is excellent in optical and
mechanical properties. The polyamide-imide film may be applicable
to various uses that require flexibility and transparency. For
example, the polyamide-imide film may be applied to solar cells,
displays, semiconductor devices, sensors, and the like.
[0096] <Process for Preparing a Polyamide-Imide Film>
[0097] The process for preparing a polyamide-imide film according
to an embodiment comprises simultaneously or sequentially mixing
and reacting a diamine compound, a dianhydride compound, and a
dicarbonyl compound in an organic solvent in a polymerization
apparatus to prepare a polymer solution; transferring the polymer
solution to a tank; casting the polymer solution in the tank and
then drying it to prepare a gel-sheet; thermally treating the
gel-sheet, while it is moved on a belt, to prepare a cured film;
and winding the cured film using a winder.
[0098] The polyamide-imide film is a film that comprises a
polyamide-imide resin as a main component. The polyamide-imide
resin is a resin that comprises, as a structural unit, an amide
repeat unit and an imide repeat unit at a predetermined molar
ratio.
[0099] In the process for preparing a polyamide-imide film, a
polymer solution for preparing the polyamide-imide resin is
prepared by simultaneously or sequentially mixing and reacting a
diamine compound, a dianhydride compound, and a dicarbonyl compound
in an organic solvent in a polymerization apparatus.
[0100] In an embodiment, the polymer solution may be prepared by
simultaneously mixing and reacting the diamine compound, the
dianhydride compound, and the dicarbonyl compound in an organic
solvent.
[0101] In another embodiment, the step of preparing the polymer
solution may comprise first mixing and reacting the diamine
compound and the dianhydride compound to produce a polyamic acid
(PAA) solution; and second mixing and reacting the polyamic acid
(PAA) solution and the dicarbonyl compound to form an amide bond
and an imide bond at the same time. The polyamic acid solution is a
solution that comprises a polyamic acid.
[0102] In still another embodiment, the step of preparing the
polymer solution may comprise first mixing and reacting the diamine
compound and the dianhydride compound to produce a polyamic acid
solution; subjecting the polyamic acid solution to dehydration to
produce a polyimide (PI) solution; and second mixing and reacting
the polyimide (PI) solution and the dicarbonyl compound to further
form an amide bond. The polyimide solution is a solution that
comprises a polymer having an imide repeat unit.
[0103] In still another embodiment, the step of preparing the
polymer solution may comprise first mixing and reacting the diamine
compound and the dicarbonyl compound to produce a polyamide (PA)
solution; and second mixing and reacting the polyamide (PA)
solution and the dianhydride compound to further form an imide
bond. The polyamide solution is a solution that comprises a polymer
having an amide repeat unit.
[0104] The polymer solution thus prepared may be a solution that
comprises a polymer containing at least one selected from the group
consisting of a polyamic acid (PAA) repeat unit, a polyamide (PA)
repeat unit, and a polyimide (PI) repeat unit.
[0105] Alternatively, the polymer comprised in the polymer solution
may comprise an imide repeat unit derived from the polymerization
of the diamine compound and the dianhydride compound and an amide
repeat unit derived from the polymerization of the diamine compound
and the dicarbonyl compound.
[0106] In an embodiment, the step of preparing the polymer solution
may further comprise introducing a catalyst.
[0107] The catalyst may include, for example, beta picoline or
acetic anhydride, but it is not limited thereto. The further
addition of the catalyst may expedite the reaction rate and enhance
the chemical bonding force between the repeat units or that within
the repeat units.
[0108] In an embodiment, the step of preparing the polymer solution
may further comprise adjusting the viscosity of the polymer
solution.
[0109] Specifically, the step of preparing the polymer solution may
comprise (a) simultaneously or sequentially mixing and reacting a
diamine compound, a dianhydride compound, and a dicarbonyl compound
in an organic solvent to prepare a first polymer solution; (b)
measuring the viscosity of the first polymer solution and
evaluating whether the target viscosity has been reached; and (c)
if the viscosity of the first polymer solution does not reach the
target viscosity, further adding the dicarbonyl compound to prepare
a second polymer solution having the target viscosity.
[0110] The target viscosity may be about 100,000 cps to about
500,000 cps at room temperature. Specifically, the target viscosity
may be about 100,000 cps to about 400,000 cps, about 100,000 cps to
about 350,000 cps, or about 100,000 cps to about 300,000 cps, but
it is not limited thereto.
[0111] In another embodiment, the content of solids contained in
the polymer solution may be 10% by weight to 20% by weight.
Specifically, the content of solids contained in the second polymer
solution may be 12% by weight to 18% by weight, but it is not
limited thereto.
[0112] If the content of solids contained in the polymer solution
is within the above range, a polyamide-imide film can be
effectively produced in the extrusion and casting steps. In
addition, the polyamide-imide film thus produced may have
mechanical properties in terms of an improved modulus and the like
and optical properties in terms of a low yellow index and the
like.
[0113] In an embodiment, the step of preparing the polymer solution
may further comprise adjusting the pH of the polymer solution. In
this step, the pH of the polymer solution may be adjusted to about
4 to about 7, for example about 4.5 to about 7.
[0114] The pH of the polymer solution may be adjusted by adding a
pH adjusting agent. The pH adjusting agent is not particularly
limited and may include, for example, amine compounds such as
alkoxyamine, alkylamine, and alkanolamine.
[0115] If the pH of the polymer solution is adjusted to the above
range, it is possible to prevent the damage to the equipment in the
subsequent process, to prevent the occurrence of defects in the
film produced from the polymer solution, and to achieve the desired
optical properties and mechanical properties in terms of yellow
index and modulus.
[0116] The pH adjusting agent may be employed in an amount of about
0.1% by mole to about 10% by mole based on the total number of
moles of monomers in the polymer solution.
[0117] The step of preparing the polymer solution may further
comprise purging the polymer solution with an inert gas. The step
of purging the polymer solution with an inert gas may remove
moisture, reduce impurities, and increase the reaction yield.
[0118] In such event, the inert gas may be at least one selected
from the group consisting of nitrogen, helium (He), neon (Ne),
argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn), but it is not
limited thereto. Specifically, the inert gas may be nitrogen.
[0119] The molar ratio of the dianhydride compound to the
dicarbonyl compound used to prepare the polymer solution may be
20:80 to 80:20, for example, 20:80 to 50:50. If the dianhydride
compound and the dicarbonyl compound are employed in the above
molar ratio, it is advantageous to achieve the desired mechanical
and optical properties of the polyamide-imide film prepared from
the polymer solution.
[0120] The polymer solution is a solution that comprises a
polyamide-imide polymer.
[0121] The diamine compound, the dianhydride compound, the
dicarbonyl compound, and the polyamide-imide polymer are as
described above.
[0122] According to another embodiment, the polymer solution may
comprise a polyamide-imide polymer formed by polymerizing a diamine
compound, a dianhydride compound, and a dicarbonyl compound,
wherein the diamine compound may comprise one kind of diamine
compound, the dianhydride compound may comprise one kind of
dianhydride compound, and the dicarbonyl compound may comprise two
kinds of dicarbonyl compound.
[0123] Alternatively, the diamine compound may be composed of one
kind of diamine compound, the dianhydride compound may be composed
of one kind of dianhydride compound, and the dicarbonyl compound
may be composed of two kinds of dicarbonyl compound.
[0124] As described above, the polyamide-imide resin, which is a
main component of the polyamide-imide film, is a resin that
comprises, as a structural unit, an amide repeat unit and an imide
repeat unit at a predetermined molar ratio.
[0125] It is possible to produce a polyamide-imide film whose
optical characteristics, mechanical properties, and flexibility are
improved in a well-balanced manner without a complicated process by
properly controlling the content of the imide repeat unit and that
of the amide repeat unit. In addition, it is possible to provide a
polyamide-imide film whose optical characteristics, mechanical
properties, and flexibility are improved in a well-balanced manner
without such steps as precipitation, filtration, drying, and
redissolution as adopted in the prior art. The content of the imide
repeat unit and that of the amide repeat unit may be controlled by
the amounts of the dianhydride and the dicarbonyl compound,
respectively.
[0126] The imide repeat unit and the amide repeat unit are as
described above.
[0127] The organic solvent may be at least one selected from the
group consisting of dimethylformamide (DMF), dimethylacetamide
(DMAc), N-methyl-2-pyrrolidone (NMP), m-cresol, tetrahydrofuran
(THF), and chloroform. Specifically, in an embodiment, the organic
solvent employed in the polymerization solution may be
dimethylacetamide (DMAc), but it is not limited thereto.
[0128] Next, after the step of preparing the polymer solution, the
polymer solution is transferred to a tank.
[0129] FIG. 7 schematically illustrates a process facility for
preparing a polyamide-imide film according to an embodiment.
Referring to FIG. 7, the polymer solution as described above is
prepared in a polymerization apparatus (10), and the polymer
solution thus produced is transferred to, and stored, in a tank
(20).
[0130] Here, once the polymer solution is prepared, the step of
transferring the polymer solution to the tank is carried out
without any additional steps. Specifically, the polymer solution
prepared in the polymerization apparatus is transferred to, and
stored in, the tank without any separate precipitation and
redissolution steps for removing impurities. In the conventional
process, in order to remove impurities such as hydrochloric acid
(HCl) generated during the preparation of a polymer solution, the
polymer solution thus prepared is purified through a separate step
to remove the impurities, and the purified polymer solution is then
redissolved in a solvent. In this case, however, there has been a
problem that the loss of the active ingredient increases in the
step of removing the impurities, resulting in decreases in the
yield.
[0131] Accordingly, the preparation process according to an
embodiment ultimately minimizes the amount of impurities generated
in the step of preparing the polymer solution or properly controls
the impurities in the subsequent steps, even if a certain amount of
impurities is present, so as not to deteriorate the physical
properties of the final film. Thus, the process has an advantage in
that a film is produced without separate precipitation or
redissolution steps.
[0132] The tank (20) is a place for storing the polymer solution
before forming it into a film, and its internal temperature may be
about -20.degree. C. to about 0.degree. C. If the temperature of
the tank (20) is controlled to the above range, it is possible to
prevent the polymer solution from deteriorating during storage, and
it is possible to lower the moisture content to thereby prevent
defects of the film produced therefrom.
[0133] The process for preparing a polyamide-imide film may further
comprise carrying out vacuum degassing of the polymer solution
transferred to the tank (20).
[0134] The vacuum degassing may be carried out for 1 hour to 2
hours after depressurizing the internal pressure of the tank to 0.2
to 0.4 bar. The vacuum degassing under these conditions may reduce
bubbles in the polymer solution. As a result, it is possible to
prevent surface defects of the film produced therefrom and to
achieve excellent optical properties such as haze.
[0135] In addition, the process for preparing a polyamide-imide
film may further comprise purging the polymer solution transferred
to the tank (20) with an inert gas.
[0136] Specifically, the purging is carried out by purging the tank
with an inert gas at an internal pressure of 1 atm to 2 atm. The
nitrogen purging under these conditions may reduce bubbles in the
polymer solution. As a result, it is possible to prevent surface
defects of the film produced therefrom and to achieve excellent
optical properties such as haze.
[0137] The step of vacuum degassing and the step of purging the
tank with nitrogen gas are performed in a separate process,
respectively.
[0138] For example, the step of vacuum degassing may be carried
out, followed by the step of purging the tank with nitrogen gas,
but it is not limited thereto.
[0139] The step of vacuum degassing and/or the step of purging the
tank with nitrogen may improve the physical properties of the
surface of the polyamide-imide film thus produced.
[0140] Thereafter, the process may further comprise storing the
polymer solution in the tank (20) for 12 hours to 60 hours. Here,
the temperature inside the tank may be kept at about -20.degree. C.
to about 0.degree. C.
[0141] The process for preparing a polyamide-imide film may further
comprise casting the polymer solution in the tank and then drying
it to prepare a gel-sheet.
[0142] The polymer solution may be cast onto a casting body such as
a casting roll or a casting belt.
[0143] Referring to FIG. 7, in an embodiment, the polymer solution
may be applied onto a casting belt (30) as a casting body, and it
is dried, while it is moved, to be made into a sheet in the form of
a gel.
[0144] When the polymer solution is injected onto the belt (30),
the injection amount may be 300 g/min to 700 g/min. If the
injection amount of the polymer solution satisfies the above range,
the gel-sheet can be uniformly formed to an appropriate
thickness.
[0145] In addition, the casting thickness of the polymer solution
may be about 200 .mu.m to about 700 .mu.m. If the polymer solution
is cast to a thickness within the above range, the final film
produced after the drying and thermal treatment may have an
appropriate and uniform thickness.
[0146] The polymer solution is cast and then dried at a temperature
of 60.degree. C. to 150.degree. C. for 5 minutes to 60 minutes to
prepare a gel-sheet. The solvent of the polymer solution is
partially or totally volatilized during the drying to prepare the
gel-sheet.
[0147] As described above, the viscosity of the polymer solution at
room temperature may be 100,000 cps to 500,000 cps, 100,000 cps to
400,000 cps, 100,000 cps to 350,000 cps, or 150,000 cps to 350,000
cps. If the viscosity satisfies the above range, the polymer
solution can be cast onto a belt in a uniform thickness without
defects.
[0148] In an embodiment, the process for preparing a
polyamide-imide film comprises thermally treating the gel-sheet,
while it is moved on the belt, to prepare a cured film.
[0149] Referring to FIG. 7, the thermal treatment of the gel-sheet
may be carried out by passing it through a thermosetting device
(40).
[0150] The thermal treatment of the gel-sheet may be carried out in
a temperature range of about 80.degree. C. to about 500.degree. C.
at a temperature elevation rate about of 2.degree. C./min to about
80.degree. C./min for about 5 minutes to about 40 minutes.
Specifically, the thermal treatment of the gel-sheet may be carried
out in a temperature range of about 80.degree. C. to about
470.degree. C. at a temperature elevation rate of about 10.degree.
C./min to about 80.degree. C./min for about 5 minutes to about 30
minutes.
[0151] In such event, the initial temperature of the thermal
treatment of the gel-sheet may be about 80.degree. C. or higher,
and the maximum temperature in the thermal treatment may be about
300.degree. C. to about 500.degree. C. For example, the maximum
temperature in the thermal treatment may be 350.degree. C. to
500.degree. C., 380.degree. C. to 500.degree. C., 400.degree. C. to
500.degree. C., 410.degree. C. to 480.degree. C., 410.degree. C. to
470.degree. C., or 410.degree. C. to 450.degree. C.
[0152] That is, referring to FIG. 7, the inlet temperature of the
thermosetting device (40) may be the initial temperature of the
thermal treatment, and the temperature of a certain region inside
the thermosetting device (40) may be the maximum temperature in the
thermal treatment.
[0153] The thermal treatment under these conditions may cure the
gel-sheet to have appropriate surface hardness and modulus and may
secure high light transmittance and low haze of the cured film at
the same time.
[0154] The process for preparing a polyamide-imide film may further
comprise, after the preparation of the cured film by thermal
treatment, cooling the cured film while it is moved on a belt.
[0155] Referring to FIG. 7, the cooling of the cured film is
carried out after it has been passed through the thermosetting
device (40). It may be carried out by using a separate cooling
chamber (not shown) or by forming an appropriate temperature
atmosphere without a separate cooling chamber.
[0156] The step of cooling the cured film while it is moved on a
belt may comprise a first temperature lowering step of reducing the
temperature at a rate of 100.degree. C./min to 1,000.degree. C./min
and a second temperature lowering step of reducing the temperature
at a rate of 40.degree. C./min to 400.degree. C./min.
[0157] In such event, specifically, the second temperature lowering
step is performed after the first temperature lowering step. The
temperature lowering rate of the first temperature lowering step
may be faster than the temperature lowering rate of the second
temperature lowering step.
[0158] For example, the maximum rate of the first temperature
lowering step is faster than the maximum rate of the second
temperature lowering step. Or the minimum rate of the first
temperature lowering step is faster than the minimum rate of the
second temperature lowering steps.
[0159] If the step of cooling the cured film is carried in such a
multistage manner, it is possible to have the physical properties
of the cured film further stabilized and to maintain the optical
properties and mechanical properties of the film achieved during
the curing step more stably for a long period of time.
[0160] The moving speed of the belt for moving the gel-sheet is the
same as the moving speed of the belt for moving the cured film.
[0161] The process for preparing a polyamide-imide film comprises
winding the cooled cured film using a winder.
[0162] Referring to FIG. 7, the cooled cured film may be wound by
using a roll-shaped winder (50).
[0163] In such event, the ratio of the moving speed of the
gel-sheet on a belt at the time of thermal treatment to the moving
speed of the cured film at the time of winding is 1:0.95 to 1:1.40.
Specifically, the ratio of the moving speeds may be 1:0.99 to
1:1.20, 1:0.99 to 1:1.10, or 1:1.10 to 1:1.05, but it is not
limited thereto.
[0164] If the ratio of the moving speeds is outside the above
range, the mechanical properties of the cured film may be impaired,
and the flexibility and elastic properties may be deteriorated.
[0165] Specifically, the belt (30) for moving the gel-sheet and the
cured film is a continuous belt on the same line. The moving speed
of the belt (30) may be about 0.1 m/min to about 15 m/min, for
example, about 0.5 m/min to about 10 m/min.
[0166] In the process for preparing a polyamide-imide film, the
thickness variation (%) according to the following Equation 1 may
be 3% to 30%, for example, 5% to 20%.
Thickness variation (%)=(M1-M2)/M2.times.100 [Equation 1]
[0167] In the above Equation 1, M1 is the thickness (.mu.m) of the
gel-sheet, and M2 is the thickness (.mu.m) of the cooled cured film
at the time of winding.
[0168] The polyamide-imide film prepared by the above preparation
process is excellent in mechanical properties and optical
properties. It is possible to impart long-term stable mechanical
properties on a substrate that requires flexibility in terms of
modulus, elongation, tensile characteristics, and elastic restoring
force.
[0169] In addition, in the conventional process for preparing a
polyamide-imide film, such byproducts as hydrochloric acid (HCl)
are generated upon the polymerization reaction. After the separate
precipitation, filtration, and drying steps to remove such
byproducts, the resultant is dissolved again in a solvent to
prepare a composition for the formation of a film. However, when
such precipitation, filtration, drying, and redissolution steps are
separately carried out, there is a problem that the yield is
remarkably lowered. In contrast, in the preparation process
according to an embodiment, the polymer solution is not ought to be
subjected to the separate precipitation, filtration, drying, and
redissolution steps. Since the polymer solution produced in the
polymerization step can be directly applied to the casting step,
the yield can be remarkably enhanced.
[0170] In addition, in the conventional process for preparing a
polyamide-imide film, a step of purging with nitrogen gas is
adopted in the thermal treatment for the formation of a film in
order to secure transparency of the film and prevent yellowing
thereof. In contrast, in the preparation process according to an
embodiment, it is possible to achieve excellent optical properties
even though the nitrogen purging is not carried out in the film
formation and thermal treatment steps. Thus, it is possible to
eliminate the possibility that impurities are adulterated in the
preparation process or that other physical properties than the
optical properties may be impaired.
[0171] According to another embodiment, there is provided a
polyamide-imide film prepared by the process for preparing a
polyamide-imide film. Here, the polyamide-imide film is as
described in the above section of <Polyamide-imide film>.
[0172] The properties of the polyamide-imide film as described
above are the results materialized by combinations of the chemical
and physical properties of the components, which constitute the
polyamide-imide film, along with the conditions in each step of the
process for preparing the polyamide-imide film as described
above.
[0173] Hereinafter, the above description will be described in
detail by referring to Examples. But the following Examples are
intended to illustrate the present invention, and the scope of the
Examples is not limited thereto only.
EXAMPLE
[0174] For Examples 1 to 3 and Comparative Examples 1 to 3,
respective raw material components were prepared according to the
composition as shown in Table 1 below.
Examples 1 to 3
[0175] A 1 L glass reactor equipped with a temperature-controllable
double jacket was charged with 403.2 g of dimethyl acetamide (DMAc)
as an organic solvent at 20.degree. C. under a nitrogen atmosphere.
Then, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) as an
aromatic diamine was slowly added thereto and dissolved.
[0176] Subsequently, while 2,2'-bis(3,4-dicarboxyphenyl)
hexafluoropropane dianhydride (6-FDA) as an aromatic dianhydride
was slowly added thereto, the mixture was stirred for 1 hour.
[0177] Then, 1,1'-biphenyl-4,4'-dicarbonyldichloride (BPDC) as a
first dicarbonyl compound was added, followed by stirring the
mixture for 1 hour. And terephthaloyl chloride (TPC) as a second
dicarbonyl compound was added, followed by stirring the mixture for
1 hour, thereby preparing a first polymer solution.
[0178] The viscosity of the first polymer solution thus prepared
was measured. If the measured viscosity did not reach the target
viscosity, a TPC solution in a DMAc organic solvent at a
concentration of 10% by weight was prepared, and 1 ml of the TPC
solution was added to the first polymer solution, followed by
stirring the mixture for 30 minutes. This procedure was repeated
until the viscosity became about 230,000 cps, thereby preparing a
second polymer solution.
[0179] The second polymer solution was transferred to a tank and
stored at -10.degree. C. The tank was degassed for 1.5 hours, so
that the pressure in the tank was about 0.3 bar. Then, the tank was
purged with a nitrogen gas at an internal pressure of 1.5 atm. Upon
the purging, the second polymer solution was stored in the tank for
48 hours.
[0180] Subsequently, the second polymer solution was cast and then
dried with hot air at 80.degree. C. for 30 minutes, thereby
producing a gel-sheet. Then, the gel-sheet was subjected to thermal
treatment in a temperature range of 80.degree. C. to 500.degree. C.
at a temperature elevation rate of 2.degree. C./min to 80.degree.
C./min for 30 minutes while it was moved on a belt. Thereafter, a
first temperature lowering step was carried out by reducing the
temperature at a rate of about 800.degree. C./min, followed by a
second temperature lowering step by reducing the temperature at a
rate of about 100.degree. C./min, thereby obtaining a
polyamide-imide film. The film was wound using a winder. In such
event, the moving speed of the gel-sheet on the belt at the time of
thermal treatment was 1 m/s. The ratio of the moving speed of the
gel-sheet on the belt at the time of thermal treatment to the
moving speed of the film at the time of winding was adjusted as
shown in Table 1 below.
Comparative Example 1
[0181] A 1 L glass reactor equipped with a temperature-controllable
double jacket was charged with 518.5 g of dimethyl acetamide (DMAc)
as an organic solvent at 20.degree. C. under a nitrogen atmosphere.
Then, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) as an
aromatic diamine was slowly added thereto and dissolved.
[0182] Subsequently, while 2,2'-bis(3,4-dicarboxyphenyl)
hexafluoropropane dianhydride (6-FDA) as an aromatic dianhydride
was slowly added thereto, the mixture was stirred for 1 hour.
[0183] Then, terephthaloyl chloride (TPC) as a dicarbonyl compound
was added, followed by stirring the mixture for 1 hour, thereby
preparing a first polymer solution. The viscosity of the first
polymer solution thus prepared was measured. If the measured
viscosity did not reach the target viscosity, a TPC solution in a
DMAc organic solvent at a concentration of 10% by weight was
prepared, and 1 mL of the TPC solution was added to the first
polymer solution, followed by stirring the mixture for 30 minutes.
This procedure was repeated until the viscosity became 100,000 cps
to 300,000 cps, thereby preparing a second polymer solution.
[0184] The second polymer solution was processed by the method
described in Example 1 to prepare a polyamide-imide film. The ratio
of the moving speed of the gel-sheet on the belt at the time of
thermal treatment to the moving speed of the film at the time of
winding was adjusted as shown in Table 1 below.
Comparative Example 2
[0185] A polyamide-imide film was prepared by the same composition
and processing method as those of Examples 1 to 3. The ratio of the
moving speed of the gel-sheet on the belt at the time of thermal
treatment to the moving speed of the film at the time of winding
was adjusted as shown in Table 1 below.
Comparative Example 3
[0186] A PET film of the brand name SH86 produced by SKC was
used.
Evaluation Example
[0187] The films of Examples 1 to 3 and Comparative Examples 1 to 3
were each measured and evaluated for the following properties.
Evaluation Example 1: Measurement of Film Thickness
[0188] The thickness was measured at 5 points in the width
direction using a digital micrometer 547-401 manufactured by
Mitutoyo Corporation. Their average value was adopted as the
thickness.
Evaluation Example 2: Measurement of Speed Ratio
[0189] The speed ratio refers to the ratio of the moving speed of
the gel-sheet on the belt at the time of thermal treatment to the
moving speed of the cured film at the time of winding. The moving
speed of the gel-sheet and that of the cured film were measured
using a contact type tachometer MS6208A of Optech.
Evaluation Example 3: Measurement of Modulus
[0190] A sample was cut out by at least 5 cm in the direction
perpendicular to the main shrinkage direction of the film and by 10
cm in the main shrinkage direction. It was fixed by the clips
disposed at intervals of 5 cm in a universal testing machine UTM
5566A of Instron. A stress-strain curve was obtained until the
sample was fractured while it was stretched at a rate of 5 mm/min
at room temperature. The slope of the load with respect to the
initial strain on the stress-strain curve was taken as the modulus
(GPa).
Evaluation Example 4: Measurement of 0.2% Off-Set and Area Value of
Elastic Region
[0191] On a stress-strain curve obtained with the UTM 5566A
universal testing machine, a parallel line was drawn as moved 0.2%
of the strain to the modulus (GPa), which is the slope of the load
for the initial strain. The strain value at the point where the
line and the stress-strain curve meet is taken as the yield point
measured by the 0.2% offset method.
[0192] The area value of the elastic region was measured as the
integral value for the stress-strain curve from the initial strain
to the yield point.
Evaluation Example 5: Measurement of Surface Hardness
[0193] The surface hardness was measured with a pencil hardness
measuring instrument (CT-PCl, CORE TECH, Korea) with a pencil
hardness measuring pencil mounted at an angle of 45.degree. and at
a pencil speed of 300 mm/min while a constant load (750 g) was
applied. The pencil used was Mitsubishi pencils having a strength
of H to 9H, F, HB, B to 6B, and the like.
Evaluation Example 6: Measurement of Yellow Index (YI)
[0194] The yellow Index (YI) was measured with a spectrophotometer
(UltraScan PRO, Hunter Associates Laboratory) using a CIE
colorimetric system.
Evaluation Example 7: Measurement of Light Transmittance and Haze
(HZ)
[0195] The light transmittance at 550 nm and the haze were measured
using a haze meter NDH-5000W manufactured by Nippon Denshoku
Kogyo.
Evaluation Example 8: Measurement of Restoring Force
[0196] The film was bent and inserted between zigs of a 5 mm
interval, and the angle was measure when it is restored after 24
hours under the conditions of 85.degree. C. and 85% RH.
TABLE-US-00001 TABLE 1 Item Ex. 1 Ex. 2 Ex. 3 C. Ex. 1 C. Ex. 2 C.
Ex. 3 Molar TFDB 0.20 0.20 0.20 0.20 0.20 -- ratio 6FDA 0.04 0.04
0.05 0.12 0.05 -- TPC 0.06 0.05 0.05 0.08 0.05 -- BPDC 0.10 0.11
0.10 -- 0.10 -- Thickness (.mu.m) 50 50 50 50 50 50 Speed ratio
1:1.01 1:1.00 1:1.01 1:1.5 1:0.85 -- Modulus (GPa) 7.37 7.35 7.09
4.24 5.34 4.35 0.2% off-set (%) 1.92 2.03 2.14 1.93 1.90 1.92
Elastic region 122.3 125.3 128.5 73.2 77.3 76.5 (J/m.sup.2 @ 0.2%)
Surface hardness 2H 2H 2H H H 6B Yellow index (YI) 3.26 3.07 3.93
1.38 2.98 0.62 Haze (%) 0.86 0.84 0.78 0.36 0.77 1.85 Transmittance
(%) 88.6 88.9 89.0 90.7 88.9 89.6 Evaluation of 67.degree. .sup.
64.degree. .sup. 68.degree. .sup. 56.degree. .sup. 59.degree. .sup.
27.degree. .sup. restoring force
[0197] As can be seen from the above Table 1, in Examples 1 to 3,
when compared with Comparative Examples 1 to 3, not only were the
mechanical properties and the optical properties excellent, but
also it was possible to secure excellent elastic area value and
excellent restoration angle at the time of evaluation of restoring
force. Thus, it may be applicable to various uses that require
flexibility and transparency.
DESCRIPTION OF THE NUMERALS
[0198] 10: polymerization apparatus [0199] 20: tank [0200] 30: belt
[0201] 40: thermosetting device [0202] 50: winder
* * * * *