Fluorine-containing polyamide acid and polyamide

Polyimides represented by general formula (I), (wherein Ar.sub.1 and Ar.sub.2 each represents an aromatic ring-containing group, Cf represents a fluorinated alkyl group directly bonded to Ar.sub.1, and m.gtoreq.1), and polyamide acids as their percursors. The polyimides have excellent humidity resistance and heat resistance, thus being useful as coating materials for semiconductor chips and insulating films for multi-layered wiring. ##STR1##

TECHNICAL FIELD 
This invention relates to fluorine-containing polyamide acids, polyimides 
obtained by curing the polyamide acids, and humidity-resistant and 
heat-resistant materials containing the said polyamides, which are useful 
as various electronics insulating films such as insulating films for 
semiconductor multi-layer wiring, a-ray shield films, flexible print 
circuit substrates, etc. 
BACKGROUND ART 
Recently, imide-based polymers have been used in surface-stabilized films 
on the exposed terminals of PN junction, interlayer insulating films of 
multi-layer wiring, .alpha.-ray shield films for preventing malfunctions 
of memory elements due to radiations (particularly, .alpha.-rays), 
flexible print circuit substrates, etc., but the ordinary polyimides have 
a high moisture absorbability in these applications and have various 
troubles due to this property. For example, an increase in leak current, 
corrosion of wiring materials (particularly in the case of aluminum), etc. 
are the problems. Furthermore, the moisture-absorbed polymers have 
problems such as swelling, when rapidly heated in the steps of gold wire 
bonding, solder reflow, etc. 
As a result of studies of heat resistance and moisture absorbability of 
polymers having various chemical structures, the present inventors have 
found that polymers of low moisture absorbability generally have a poor 
heat resistance. For example, in comparison with polyimides having 
repetition units of the following formula (A), polyimides having 
repetition units of the following formula (B) have a moisture 
absorbability reduced to about 1/3, but have a lower thermal decomposition 
temperature even by 40.degree. C. 
##STR2## 
Likewise, polymers having repetition units of the following formula (C) 
have a moisture absorbability reduced to about 1/4 and a lower thermal 
decomposition temperature by about 100.degree. C., as compared with the 
polyimides of formula (A). 
##STR3## 
An object of the present invention is to provide novel polyimides having a 
low moisture absorbability and a distinguished heat resistance and being 
particularly useful for applications as various insulating films in 
electronics, and also provide polyamide acids as raw materials for them. 
DISCLOSURE OF INVENTION 
In summary, the first aspect of the present invention relates to polyamide 
acids characterized by containing repetition units represented by the 
following general formula I: 
##STR4## 
wherein Ar.sub.1 and Ar.sub.2 represent groups containing hydrocarbon 
rings; R represents hydrogen or alkyl groups having 1 to 4 carbon atoms; 
Cf represents a fluorinated alkyl group directly bonded to a hydrocarbon 
ring as a pendant radical m.gtoreq.1. 
The second aspect of the present invention relates to polyimides 
characterized by containing repetition units represented by the following 
general formula II: 
##STR5## 
(wherein Ar.sub.1, Ar.sub.2, Cf and m have the same meanings as defined 
above for the said formula I). 
The polyimides according to the present invention are materials having 
distinguished moisture resistance and heat resistance, and are useful as 
electric insulating materials, functioning materials, etc. 
As least one of the following diamines is used as the 
##STR6## 
(wherein Cf is fluoroalkyl groups having 1 to 4 carbon atoms; n, p, q, and 
r are integers of 0 or 4 and n+p+q+r.gtoreq.1). 
Among the polyamide acids represented by the general formula I, 
particularly the following polyamide acids are practically distinguished: 
##STR7## 
(wherein Ar.sub.1 --(CF.sub.3).sub.m ' is at least one of 
##STR8## 
Ar.sub.2 is at least one of 
##STR9## 
n', p', q' and r' are 0 to 4). 
Particularly, the following polyamide acids are useful: 
##STR10## 
(wherein Ar.sub.1 is any one of 
##STR11## 
The polymides (formula II) of the present invention can be obtained by 
heating the polyamide acids, thereby imidizing them through dehydration 
and ring closure. 
Among the present polyamide acids and polymides, it has been found that 
those obtained from pyromellitic acid dianhydride and 
4,4'-bis[3-trifluoromethyl)-4-aminophenoxy] biphenyl, from pyromellitic 
acid dianhydride and p-bis[2-(trifluoromethyl)-4-aminophenoxy] benzene, 
and from pyromellitic acid dianhydride, benzophenone-3,3', 4,4' 
-tetracarboxylic acid dianhydride, 4,4'-bis[3-(trifluoromethyl) 
-4-aminophenoxy]-biphenyl, and 3-carbamoyl-4,4'-diaminodiphenyl ether have 
distinguished characteristics. 
As a result of studies of heat resistance and moisture resistance of 
various polymers, the present inventors have found that polymers having a 
fluorinated alkyl group in the molecular structure have a high heat 
resistance and a low moisture absorbability. 
The heat resistance includes a heat resistance from the viewpoint of 
thermal decomposition temperature and a heat resistance from the viewpoint 
of glass transition point (Tg). The present inventors have found that Tg 
generally has a decreasing tendency by introduction of a fluorinated alkyl 
group, and when the fluorinated alkyl group exists as a side chain through 
direct bonding to an aromatic ring, particularly to a benzene ring, the 
moisture absorbability decreases likewise, but the decrease in Tg is very 
small. Various polymers having such skeletons are available, among which 
it has been newly found as a result of studies from the overall viewpoints 
of thermal decomposition temperature, Tg, mechanical strength, 
processability, cost, etc. that polyimides containing repetition units 
represented by the said formula II according to the present invention are 
useful. 
The present polyimides or their precursors polyamide acids can be obtained 
by introducing a fluorinated alkyl group into the aromatic ring of 
diamine, followed by their reaction. 
Examples of diamines, in which the florinated alkyl group is directly 
bonded to the aromatic ring, as one of the raw materials in the present 
invention include: diaminobenzotrifluoride, 
bis(trifluoromethyl)phenylenediamine, 
diaminotetra(trifluoromethyl)benzene, diamino(pentafluoroethyl)benzene, 
2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, 
2,2'-bis(trifluoromethyl) -4,4'-diaminodiphenyl ether, 
3,3'-bis(trifluoromethyl) -4,4'-diaminodiphenyl ether, 
3,3',5,5'-tetrakis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 
3,3'-bis(trifluoromethyl)-4,4'-diaminobenzophenone, bis(aminophenoxy) 
-di-(trifluoromethyl)benzene, bis(aminophenoxy) 
tetrakis(trifluoromethyl)benzene, 
bis[(trifluoromethyl)aminophenoxy]benzene, 
bis[(trifluoromethyl)aminophenoxy]biphenyl, 
bis{[(trifluoromethyl)aminophenoxy]phenyl}hexafluoropropane, etc. 
It is most reasonable to prepare the present polyamide acids through 
reaction of diamine and tetracarboxylic acid dianhydride given by the 
following general formulae in chemical equivalent amounts or amounts near 
thereto (particularly 0.9 to 1.1 moles of the diamine per mole of the 
carboxylic acid anhydride) in a solvent: 
##STR12## 
The solvent for use in the reaction can be N-methyl-2-pyrrolidone, etc. as 
used in the synthesis of polyamino acid so far well known. 
The sheleton is which the fluorinated alkyl group is directly bonded to the 
aromatic ring in the present invention includes, for example, the 
following structural units: 
##STR13## 
Examples of the aromatic diamine which can be used together with the said 
diamine include the following ones: 
Diamines represented by the following general formula III: 
##STR14## 
(wherein l is number of 1 to 6), for example, 
1,3-bis(aminophenyl)hexafluoropropane, or 
2,2-bis[(aminophenoxy)phenyl]hexafluoropropane, 
bis{2-[(aminophenoxy)phenyl]hexafluoroisopropyl}benzene, 
m-phenylenediamine, p-phenylenediamine, benzidine, 4,4"-diaminoterphenyl, 
4,4"'-diaminoquaterphenyl, 4,4'-diaminodiphenyl ether, 
4,4'-aminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 
2,2-bis(p-aminophenyl)propane, 1,5-diaminonaphthalene, 
2,6-diaminonaphthalene, 3,3'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 
3,3'-dimethyl-4,4'-diaminodiphenyl ether, 
3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1,4-bis(p-aminophenoxy)benzene, 
4,4'-bis(p-aminophenoxy) biphenyl, 2,2-bis[4-(p-aminophenoxy)phenyl] 
propane, 2,3,5,6-tetramethyl-p-phenylenediamine, etc. 
To improve adhesion to glass, ceramics, and metals, silicon-containing 
diamines represented by the general formulae: 
##STR15## 
(wherein R.sub.2 and R.sub.4 are divalent organic groups; R.sub.1 and 
R.sub.3 are monovalent organic groups; p and q are integers of more than 
1) can be used together. 
In the synthesis of the present polyamino acids, the diamines and acid 
anhydrides given by the formulae [III] and [IV] should be the main raw 
materials. For example, the amount of diamine [III] should be 70% or more 
of the total diamine components and that of acid anhydride [IV] should be 
50% or more of the total acid anhydrides, or otherwise no polyimides 
having both distinguished moisture resistance and heat resistance can be 
obtained. 
The tetracarboxylic acid derivatives for use in the present invention 
include aromatic tetracarboxylic acids, or their acid dianhydrides, their 
partially esterified products with lower alcohols, etc. such as 
pyromellitic 
acid, 3,3',4,4'-tetracarboxybiphenyl, 2,3,3',4'-tetracarboxybiphenyl, 
3,3',4,4'-tetracarboxydiphenyl ether, 2,3,3',4'-tetracarboxydiphenyl 
ether, 3,3',4,4'-tetra carboxybenzophenone, 
2,3,3',4'-tetracarboxybenzophenone, 2,3,6,7-tetracarboxynaphthalene, 
1,4,5,8-tetracarboxynaphthalene, 1,2,5,6-tetracarboxynaphthalene, 
3,3',4,4'-tetracarboxydiphenylmethane, 2,2-bis(3,4-dicarboxyphenyl) 
propane, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, 
3,3',4,4'-tetracarboxydiphenyl sulfone, 3,4,9,10-tetracarboxyperylene, 
2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane, 
2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane, etc. 
The present polyamide acids can be synthesized in a solvent such as 
N-methyl-2-pyrrolidone (which will be hereinafter referred to as NMP), 
dimethylformamide, dimethylacetamide, sulfolane, cresol, xylenol, 
halogenated phenol, etc. The present polyamide acids have such a feature 
as a distinguished solubility in these solvents. Thus, a low cost solvent 
such as dichlorobenzene, acetone, methylethylketone, diacetone alcohol, 
etc. can be used as mixed. 
The polyamide acids thus synthesized can be utilized, for example, as a 
varnish at a concentration of 1 to 30% (by weight, resin component) in the 
production of polyimide films, or used as a varnish as such in coating 
semi-conductor chips (IC, LSI, etc.). 
To improve the solvent resistance of polyimide, it is useful (i) to 
introduce an amino group, carbamoyl group or sulfamoyl group further into 
the diamine to form a rigid ladder structure after the curing, (ii) to 
introduce a nadic acid derivative or an unsaturated group such as ethinyl 
group, etc. therein to conduct heat cross-linking, and (iii) to introduce 
a hydroxyl group or carboxyl group into the polymer to conduct 
cross-linking by addition of a curing agent. In addition, tricarboxylic 
acid derivatives can be used together. 
An example of synthesizing raw materials is given below: 
SYNTHESIS EXAMPLE 
Charged into a four-necked flask having a stirring rod, a reflux condenser 
with a water recipient, a thermometer and a nitrogen gas injection inlet 
were 10.3 g (0.0566 moles) of bisphenol, 100 g of dimethyl sulfoxide, and 
16.4 g of toluene. They were mixed with stirring and subjected to 
dissolution. An aqueous solution of 4.5 g (0.113 moles) of sodium 
hydroxide in 4.5 g of water was added thereto, and the mixture was 
refluxed with stirring and dehydrated. After no water was evolved, the 
condenser was replaced with a Liebig condenser, and the mixture was heated 
up to about 160.degree. C. to remove the remaining water and toluene 
therefrom by distillation. 
Then, the residue was cooled to 100.degree. C., and then 25.5 g (0.113 
moles) of 2-nitro-5-chlorobenzotrifloride was added thereto, and the 
mixture was subjected to reaction with stirring for about 5 hours. The 
reaction mixture was poured into 1,000 ml of water, whereby yellow 
precipitates were formed. The precipitates were recovered by filtration 
and thoroughly washed with water, and dried at 60.degree. C. under reduced 
pressure, whereby 30 g of 4,4'-bis[-(trifluoromethyl) 
-4-nitrophenoxy]biphenyl was obtained (yield: 94%). 
Then, 30 g (0.053 moles) of 4,4'-bis[2-(trifluoromethyl) 
-4-nitrophenoxy]biphenyl was dissolved in 228 g of benzene, and activated 
iron consisting of 104 g of iron powder and 25 g of concentrated 
hydrochloric acid was added thereto. The mixture was heated at 70.degree. 
C. for 2 hours with stirring. Then, 20 g of water was added thereto, and 
the mixture was further refluxed for 2 hours. After cooling, the benzene 
layer was separated. By evaporation of the benzene solution, yellow powder 
was obtained. It was found by infrared absorption spectrum that the nitro 
group was reduced to an amino group and 
4,4'-bis[3-(trifluoromethyl)4-aminophenoxy]biphenyl was formed, which will 
be hereinafter referred to as TFAPB. 
BEST MODE FOR CARRYING OUT THE INVENTION 
The present invention will be described in detail, referring to Examples. 
Abbreviations of compound names in Examples are summarized below: 
BPDA: biphenyl-3,3',4,4'-tetracarboxylic acid dianhydride 
BTDA: benzophenone-3,3',4,4'-tetracarboxylic acid dianhydride 
DAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane 
DAPFP: 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane 
DCPFP: 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafloropropane dianhydride 
DFAPFP: 2,2-bis{4-[trifluoromethyl)-4-aminophenoxy] 
phenyl}hexafluoropropane 
DDE: 4,4'-diaminodiphenyl ether 
PMDA: pyromelltic acid dianhydride 
TFAPB: 4,4'-bis[3-(trifluoromethyl)-4-aminophenoxy]biphenyl

EXAMPLE 1 
Charged in a four-necked flask having a stirring rod, a reflux condenser, a 
thermometer and a nitrogen gas injection inlet were 31.42 g (0.0623 moles) 
of TFAPB and 255 g of NMP, and they were dissolved. Then, 13.58 g (0.0623 
moles) of PMDA was added thereto portion by portion, and then the mixture 
was subjected to reaction for about 5 hours, whereby a polyamide acid 
varnish was obtained. 
The varnish was extended thinly on a glass plate and heated at 100.degree. 
C. for one hour to prepare a film. The film was peeled off from the glass 
plate, and inserted between metal frames and heated at 200.degree. C. for 
one hour and further at 400.degree. C. for one hour to obtain a polyimide 
film (about 30 .mu.m). 
The heat resistance of the film was evaluated in the air, and it was found 
that the time of 3% reduction in amount was 6 minutes at 500.degree. C., 
20 minutes at 475.degree. C., 70 minutes at 450.degree. C., and 125 
minutes at 425.degree. C. 
It is seen from this result that the temperature requiring 100 minutes for 
3% reduction in amount (which is defined as thermal decomposition 
temperature) is 440.degree. C. 
As a result of subjecting the film to moisture absorption at 25.degree. C. 
and 75% RH, it was found that the moisture absorbability was 0.7%, which 
was lower than that of the ordinary polyimide. 
A glass transition temperature (Tg) was determined from a dimensional 
change measured by a thermomechanical analyzer at a constant rate 
temperature elevation at 10.degree. C./ hour when the polyimide film was 
inserted between glass plates and heated to 400.degree. C. It was found 
that Tg was 400.degree. C. 
COMATIVE EXAMPLE 1 
(1) A polyamide acid varnish was synthesized in the following mixing ratio 
in the same manner as in Example 1, and further a polyimide film was 
prepared. 
______________________________________ 
4,4'-(4-aminophenoxy)biphenyl 
28.27 g 
PMDA 16.73 g 
NMP 255 g 
______________________________________ 
Then, thermal decomposition temperature, moisture absorbability, and Tg 
were measured in the same manner as in Example 1, and were found to be 
435.degree. C., 2.05% and 340.degree. C., respectively. 
In comparison with the polyimide of Example 1, the said polyimide has a 
lower Tg by 60.degree. C. and an about 3-fold moisture absorbability. 
(2) A polyamide acid varnish was synthesized in the following mixing ratio 
in the same manner as in Example 1, and further a polyimide film was 
prepared. Then, thermal decomposition temperature, moisture absorbability 
and Tg were measured in the same manner as in Example 1, and were found to 
be 430.degree. C., 1.7%, and 180.degree. C., respectively. 
______________________________________ 
1,3-bis(4-aminophenyl)hexafluoropropane 
26.28 g 
PMDA 18.72 g 
NMP 255 g 
______________________________________ 
In comparison with the polyimide of Example 1, Tg of the said polyimide was 
lower by more than 200.degree. C., and the moisture absorbability was no 
more lowered. 
(3) A polyamide acid varnish was synthesized in the following mixing ratio 
in the same manner as in Example 1, and further a polyimide film was 
prepared. Then, thermal decomposition temperature, moisture absorbability, 
and Tg were measured in the same manner as in Example 1, and were found to 
be 420.degree. C., 1.2% and 150.degree. C., respectively. 
______________________________________ 
1,5-bis(4-aminophenyl)decafluoropentane 
29.28 g 
PMDA 15.72 g 
NMP 255 g 
______________________________________ 
Only introduction of --CF.sub.2 --.sub.n into the diamine skeleton as above 
lowers Tg, and does not too much lower the moisture absorbability. 
EXAMPLE 2 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. 
______________________________________ 
2,5-diaminobenzotrifluoride 
15.90 g 
BTDA 29.10 g 
NMP 255 g 
______________________________________ 
Then, thermal decomposition temperature, moisture absorbability, and Tg 
were measured in the same manner as in Example 1, and were found to be 
470.degree. C., 0.6% and 350.degree. C., respectively. 
COMATIVE EXAMPLE 2 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. p-phenylenediamine 11.31 g 
______________________________________ 
p-phenylenediamine 
11.31 g 
BTDA 33.69 g 
NMP 255 g 
______________________________________ 
Then, thermal decomposition temperature, moisture absorbability, and Tg 
were measured in the same manner as in Example 1, and were found to be 
470.degree. C., 3.0% and 370.degree. C., respectively. 
EXAMPLE 3 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. 
______________________________________ 
p-bis[2-(trifluoromethyl)-4-aminophenoxy] 
29.82 g 
benzene 
PMDA 15.18 g 
NMP 255 g 
______________________________________ 
Then, thermal decomposition temperature, moisture absorbability, and Tg 
were measured in the same manner as in Example 1, and were found to be 
440.degree. C., 0.85% and 380.degree. C., respectively. 
COMATIVE EXAMPLE 3 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. 
______________________________________ 
1,4-bis(4-aminophenoxy)benzene 
24.65 g 
PMDA 20.35 g 
NMP 255 g 
______________________________________ 
Then, thermal decomposition temperature, moisture absorbability, and Tg 
were measured in the same manner as in Example 1, and were found to be 
430.degree. C., 2.22% and 325.degree. C., respectively. In comparison with 
Example 3, the moisture absorbability was made much smaller and Tg was 
also made higher by about 50.degree. C. by introduction of the 
trifluoromethyl group. 
EXAMPLE 4 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was prepared 
______________________________________ 
DFAPFP 33.75 g 
PMDA 11.25 g 
NMP 255 g 
______________________________________ 
Then, thermal decomposition temperature, moisture absorbability and Tg were 
measured in the same manner as in Example 1, and were found to be 
440.degree. C., 0.5% and 360.degree. C., respectively. 
COMATIVE EXAMPLE 4 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. 
______________________________________ 
DAPP 29.39 g 
PMDA 15.61 g 
NMP 255 g 
______________________________________ 
Then, thermal decomposition temperature, moisture absorbability, and Tg 
were measured in the same manner as in Example 1, and were found to be 
400.degree. C., 0.9% and 350.degree. C., respectively. 
EXAMPLE 5 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. 
______________________________________ 
DFAPFP 20.04 g 
DCPFP 24.96 g 
NMP 255 g 
______________________________________ 
Then, thermal decomposition temperature, moisture absorbability, and Tg 
were measured in the same manner as in Example 1, and were found to be 
430.degree. C., 0.4% and 235.degree. C. 
COMATIVE EXAMPLE 5 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. 
______________________________________ 
2,2-bis{4-(aminophenoxy)phenyl}hexafluoro- 
20.34 g 
propane 
DCPFP 24.66 g 
NMP 255 g 
______________________________________ 
Then, thermal decomposition temperature, moisture absorbability, and Tg 
were measured in the same manner as in Example 1, and were found to be 
430.degree. C., 0.6% and 220.degree. C., respectively. 
In comparison with Example 5, the moisture absorbability was 1.5-fold, and 
Tg was also a little lower. 
EXAMPLE 6 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1. Owing to the use of trimellitic acid 
anhydride, a low molecular weight oligomers were formed under the reaction 
conditions. Then, the varnish was applied to a glass plate, and heated, 
whereby a polyimide film partially having amide bonds was obtained. 
______________________________________ 
TFAPB 24.21 g 
DDE 4.12 g 
BPDA 10.09 g 
Trimellitic acid anhydride 
6.59 g 
NMP 255 g 
______________________________________ 
Then, thermal decomposition temperature, moisture absorbability, and Tg 
were measured in the same manner as in Example 1, and were found to be 
400.degree. C., 0.7% and 350.degree. C., respectively. 
COMATIVE EXAMPLE 6 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. 
Then, thermal decomposition temperature, moisture absorbability. and Tg 
were measured in the same manner as in Example 1, and were found to be 
450.degree. C., 1.8% and 370.degree. C., respectively. 
______________________________________ 
4,4'-bis(4-aminophenoxy)biphenyl 
20.30 g 
DDE 5.74 g 
PMDA 12.02 g 
BPDA 6.95 g 
NMP 255 g 
______________________________________ 
EXAMPLE 7 
A modified polyamide acid varnish was synthesized in the following mixing 
ratio in the same manner as in Example 1, and further a polyimide film was 
prepared. 
______________________________________ 
TFAPB 23.82 g 
3-carbamoyl-4,4'-diaminodiphenyl 
4.92 g 
ether 
PMDA 10.30 g 
BPDA 6.00 g 
NMP 255 g 
______________________________________ 
Then, the physical properties were measured in the same manner as in 
Example 1, and it was found that thermal decomposition temperature was 
450.degree. C., moisture absorbability 0.8%, and Tg 400.degree. C. 
EXAMPLE 8 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. 
______________________________________ 
TFAPB 23.48 g 
DDE 3.99 g 
BPDA 13.69 g 
Trimellitic acid anhydride 
3.83 g 
NMP 255 g 
______________________________________ 
Then, thermal decomposition temperature, moisture absorbability and Tg were 
measured in the same manner as in Example 1, and were found to be 
425.degree. C., 0.78% and 315.degree. C., respectively. 
EXAMPLE 9 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. 
______________________________________ 
DFADFP 31.04 g 
BPDA 13.96 g 
NNP 255 g 
______________________________________ 
Thermal decomposition temperature, moisture absorbability and Tg of the 
film were 450.degree. C., 0.53% and 305.degree. C., respectively. 
EXAMPLE 10 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. 
______________________________________ 
TFAPB 30.32 g 
PMDA 9.83 g 
BTDA 4.84 g 
NMP 255 g 
______________________________________ 
Thermal decomposition temperature, moisture absorbability and Tg of the 
film were 440.degree. C., 0.73 and 350.degree. C., respectively. 
EXAMPLE 11 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. 
______________________________________ 
3,5-bis(aminophenoxy)-tert-nanofluorobutyl- 
30.99 g 
benzene 
PMDA 14.01 g 
NMP 255 g 
______________________________________ 
Then, thermal decomposition temperature, moisture absorbability, and Tg 
were measured in the same manner as in Example 1, and were found to be 
420.degree. C., 0.6% and 320.degree. C., respectively. 
EXAMPLE 12 
A polyamide acid varnish was synthesized in the following mixing ratio in 
the same manner as in Example 1, and further a polyimide film was 
prepared. Then, thermal decomposition temperature, moisture absorbability 
and Tg were measured in the same manner as in Example 1, and were found to 
be 440.degree. C., 0.35% and 430.degree. C., respectively. 
______________________________________ 
4,4'-bis(2-trifluoromethyl-4-aminophenoxy)- 
34.84 g 
3,3',5,5'-tetrakis(trifluoromethyl)biphenyl 
PMDA 10.16 g 
NMP 255 g 
______________________________________ 
INDUSTRIAL APPLICABILITY 
As described in detail above, novel polyamide acids and polyimides are 
provided according to the present invention, and moisture-resistant and 
heat-resistant materials containing the said polyimides have remarkable 
effects in distinguished moisture resistance and heat resistance, 
different from the conventional ones. Thus, novel materials are provided 
in the field of electronics materials.