U.S. patent application number 11/443000 was filed with the patent office on 2006-11-30 for thermosetting solution composition and prepreg.
This patent application is currently assigned to UBE INDUSTRIES, LTD.. Invention is credited to Fumio Aoki, Hiroaki Yamaguchi.
Application Number | 20060270826 11/443000 |
Document ID | / |
Family ID | 36790843 |
Filed Date | 2006-11-30 |
United States Patent
Application |
20060270826 |
Kind Code |
A1 |
Yamaguchi; Hiroaki ; et
al. |
November 30, 2006 |
Thermosetting solution composition and prepreg
Abstract
A thermosetting solution composition composed of a
biphenyltetracarboxylic acid compound containing a partial lower
aliphatic alkyl ester of 2,3,3',4'-biphenyltetracarboxylic acid
and/or a partial lower aliphatic alkyl ester of
2,2',3,3'-biphenyltetracarboxylic acid, an aromatic diamine
compound in a molar amount larger than a molar amount of the
biphenyltetracarboxylic acid compound, a partial lower aliphatic
aryl ester of 4-(2-phenylethynyl)phthalic acid compound in a molar
amount as much as 1.8-2.2 times a molar amount corresponding to a
difference between the molar amount of the aromatic diamine
compound and the molar amount of the biphenyltetracarboxylic acid
compound, and an organic solvent composed of a lower aliphatic
alcohol is of value for manufacture of a prepreg.
Inventors: |
Yamaguchi; Hiroaki;
(Yamaguchi, JP) ; Aoki; Fumio; (Chiba,
JP) |
Correspondence
Address: |
NIXON PEABODY, LLP
401 9TH STREET, NW
SUITE 900
WASHINGTON
DC
20004-2128
US
|
Assignee: |
UBE INDUSTRIES, LTD.
Ube-shi
JP
|
Family ID: |
36790843 |
Appl. No.: |
11/443000 |
Filed: |
May 31, 2006 |
Current U.S.
Class: |
528/353 |
Current CPC
Class: |
C08J 2379/08 20130101;
C08G 73/1042 20130101; C08G 73/1003 20130101; C08L 79/08 20130101;
C08G 73/1078 20130101; C08J 5/24 20130101; Y10T 428/24994
20150401 |
Class at
Publication: |
528/353 |
International
Class: |
C08G 69/26 20060101
C08G069/26 |
Foreign Application Data
Date |
Code |
Application Number |
May 31, 2005 |
JP |
2005-160585 |
Dec 1, 2005 |
JP |
2005-348407 |
Apr 19, 2006 |
JP |
2006-116076 |
Claims
1. A thermosetting solution composition comprising a
biphenyltetracarboxylic acid compound containing at least 15 mol %
of a partial lower aliphatic alkyl ester of
2,3,3',4'-biphenyltetracarboxylic acid and/or a partial lower
aliphatic alkyl ester of 2,2',3,3'-biphenyltetracarboxylic acid, an
aromatic diamine compound in a molar amount larger than a molar
amount of the biphenyltetracarboxylic acid compound, a partial
lower aliphatic alkyl ester of 4-(2-phenylethynyl)phthalic acid
compound in a molar amount as much as 1.8-2.2 times a molar amount
corresponding to a difference between the molar amount of the
aromatic diamine compound and the molar amount of the
biphenyltetracarboxylic acid compound, and an organic solvent
comprising a lower aliphatic alcohol.
2. The thermosetting solution composition of claim 1, wherein the
lower aliphatic alcohol is methanol or ethanol.
3. The thermosetting solution composition of claim 1, wherein each
of the partial lower aliphatic alkyl esters is a partial methyl
ester or a partial ethyl ester.
4. The thermosetting solution composition of claim 1, wherein the
molar amount of the partial lower aliphatic alkyl ester of
4-(2-phenylethynyl)phthalic acid compound is as much as 1.95-2.05
times a molar amount corresponding to the difference the molar
amount of the aromatic diamine compound and the molar amount of the
biphenyltetracarboxylic acid compound.
5. The thermosetting solution composition of claim 1, wherein a
total amount of the biphenyltetracarboxylic acid compound, the
aromatic diamine compound, and 2-(2-phenylethynyl)phthalic acid
compound is in the range of 30 to 80 wt. %, per the amount of the
solution composition.
6. The thermosetting solution composition of claim 1, wherein the
biphenyltetracarboxylic acid compound comprises at least 50 molar %
of 2,3,3',4'-biphenyltetracarboxylic acid compound comprising a
partial lower aliphatic alkyl ester of
2,3,3',4'-biphenyltetracarboxylic acid compound.
7. The thermosetting solution composition of claim 1, wherein the
aromatic diamine compound comprises at least 50 molar % of an
aromatic diamine having one aromatic ring in a molecular structure
thereof.
8. The thermosetting solution composition of claim 1, wherein the
aromatic diamine compound comprises p-phenylenediamine,
1,3-bis(4-aminophenoxy)enzene, or a mixture thereof.
9. The thermosetting solution composition of claim 1, which further
comprises an imidazole compound.
10. A thermosetting solution composition comprising a
biphenyltetracarboxylic acid contend containing at least 15 mol %
of a partial methyl ester of 2,3,3',4'-biphenyltetracarboxylic acid
and/or a partial methyl ester of 2,2',3,3'-biphenyltetracarboxylic
acid, an aromatic diamine compound in a molar amount larger than a
molar amount of the biphenyltetracarboxylic acid compound, a
partial methyl ester of 4-(2-phenylethynyl)-phthalic acid compound
in a molar amount as much as 1.8-2.2 times a molar amount
corresponding to a difference between the molar amount of the
aromatic diamine compound and the molar amount of the
biphenyltetracarboxylic acid compound, and an organic solvent
comprising ethanol.
11. A thermosetting powder composition comprising a
biphenyltetracarboxylic acid compound containing at least 15 mol %
of a partial lower aliphatic alkyl ester of
2,3,3',4'-biphenyltetracarboxylic acid and/or a partial lower
aliphatic alkyl ester of 2,2',3,3'-biphenyltetracarboxylic acid, an
aromatic diamine compound in a molar amount larger than a molar
amount of the biphenyltetracarboxylic acid compound, and a partial
lower aliphatic alkyl ester of 4-(2-phenylethynyl)phthalic acid
compound in a molar amount as much as 1.8-2.2 times a molar amount
corresponding to a difference between the molar amount of the
aromatic diamine compound and the molar amount of the
biphenyltetracarboxylic acid compound.
12. The thermosetting powder composition of claim 11, wherein each
of the partial lower aliphatic alkyl ester is a partial methyl
ester.
13. A prepreg comprising a sheet matrix of a reinforcing fiber
impregnated with the thermosetting solution composition of claim
1.
14. A prepreg comprising a sheet matrix of a reinforcing fiber
impregnated with the thermosetting solution composition of claim
10.
15. A method of manufacturing a resin article which comprises
laminating a plural number of the prepregs defined in claim 13 one
on another and heating the resulting laminate under pressure.
16. A method of manufacturing a resin article which comprises
laminating a plural number of the prepregs defined in claim 14 one
on another and heating the resulting laminate under pressure.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a thermosetting solution
composition, a prepreg utilizing the same, and a method for
manufacturing an aromatic polyimide resin article from the prepreg.
In particular, the invention relates to a thermosetting solution
composition favorably employable for manufacturing a prepreg and
further an aromatic polyimide resin article.
BACKGROUND OF THE INVENTION
[0002] It is known that an aromatic polyimide resin article shows
very favorable physical and chemical characteristics such as high
mechanical strength, high heat resistance, and high resistance to
chemical compounds. Accordingly, the aromatic polyimide resin has
been widely employed for manufacturing substrate plates of
electronic devices. The favorable physical and chemical
characteristics of the aromatic polyimide resin have recently
received increased attention, and hence the aromatic polyimide
resin has been studied for the use in manufacturing various
constitutional units of aeroplane and spacecraft. In fact, some
aromatic polyimide resin articles are employed in these technical
fields.
[0003] An aromatic polyimide article such as an aromatic polyimide
sheet is generally manufactured by first preparing a solution of a
polyamic acid (i.e., polyamide acid) by the reaction between an
aromatic tetracarboxylic acid derivative and an aromatic diamine in
a solvent, spreading the polyamic acid solution on a temporary
support to prepare a polyamic acid sheet, and finally heating the
polyamic acid sheet to give the polyimide sheet upon drying and
cyclization reaction.
[0004] An aromatic polyimide article having a large thickness or an
aromatic polyimide article of non-sheet form is generally
manufactured utilizing a plurality of prepregs. A plurality of the
prepregs are laminated one on another and then heated under
pressure to give an aromatic polyimide article. The prepreg is
prepared by impregnating a sheet matrix of a reinforcing fiber with
a thermosetting polymer solution composition.
[0005] Japanese PC publication 2002-511902 discloses a method of
preparing a prepreg from a polyimide precursor solution which has a
solid concentration of 50 to 80 wt. %, a volatile concentration of
not higher than 35 wt. %, and a Brookfield viscosity of 4,000 to
10,000 cP. The typical polyimide precursor solution is prepared
from oxydiphthalic dianhydride, phthalic acid and
3,4'-oxydianiline. The solvent of the solution typically is a
mixture of N-methyl-2-pyrrolidone and ethanol.
[0006] Japanese Provisional Patent Publication 2000-219741 A
describes a termin modified imide oligomer solution (thermosetting
solution composition) which is obtained by the reaction of
2,3,3',4'-biphenyltetracarboxylic acid with an aromatic diamine
compound and 4-(2-phenylethynyl)phthalic anhydride and further
describes that the solution composition is employable for
manufacturing a prepreg and further an aromatic polyimide article
(i.e., cured article). The publication describes a list of solvents
employable for the preparation of the solution composition which
includes N-methyl-2-pyrrolidone, N,N-dimethylformamide,
N,N-diethylacetamide, N,N-diethylacetamide, and N-caprolactam.
[0007] Japanese Provisional Patent Publication 2004-331801 A
describes that 2,2',3,3'-biphenyltetracarboxylic dianhydride is
employable for the preparation of an aromatic polyimide as the
aromatic tetracarboxylic acid compound, and further describes that
the dianhydride is reacted with an aromatic diamine compound in the
presence of a reactive crosslinked agent to give a polyamic acid
oligomer.
[0008] The thermosetting solution composition comprising the
terminal modified imide oligomer solution prepared by the reaction
of 2,3,3',4'-biphenyltetracarboxylic acid with an aromatic diamine
compound and 4-(2-phenylethynyl)phthalic anhydride in a solvent is
of value for preparing an aromatic polyimide article (i.e., cured
article) having excellent physical and chemical properties.
However, all solvents described in the publication as the solvents
employable for the preparation of the imide, that is,
N-methyl-2-pyrrolidone, N,N-dimethylformamide,
N,N-dimethylacetamide, N,N-diethylacetamide, and N-caprolactam,
have a high boiling point. Therefore, removal of the solvent from
the solution composition by evaporation requires high temperatures
and long periods of time. These evaporation conditions are not
favorable from the viewpoint of industrial preparation.
SUMMARY OF THE INVENTION
[0009] Accordingly, it is an object of the present invention to
provide a thermosetting solution composition which is easily
removed by distillation in the process of preparation of a prepreg
for the use of manufacture of an aromatic polyimide article (i.e.,
cured article) and further in the process of the manufacture of the
cured article and further which is easily handled in the industrial
process.
[0010] It is another object of the invention to provide a prepreg
which is favorably employable for manufacture of an aromatic
polyimide article (i.e., cured article) by way of heating under
pressure from the viewpoints that the solvent used as well as water
and alcohol which are by-produced in these processes are easily
removed by evaporation.
[0011] The inventors of the present invention have noted and
studied the thermosetting solution composition described in
Japanese Provisional Patent Publication 2000-219741 A. As a result
of the studies, they have discovered that when
2,3,3',4'-biphenyltetracarboxylic dianhydride and
4-(2-phenylethynyl)phthalic anhydride are dissolved in a lower
aliphatic alcohol such as methanol or ethanol and heated, a partial
lower aliphatic alkyl ester of 2,3,3',4'-biphenyltetracarboxylic
acid and a partial lower aliphatic alkyl ester of
4-(2-phenylethynyl)phthalic acid both of which are soluble in the
employed alcohol are produced, and that a solution composition
comprising the resulting solution and an aromatic diamine compound
shows a stable solution viscosity. The inventors have further
discovered that the resulting solution composition is favorably
employable for preparing a prepreg and furthermore that the prepreg
is easily converted into a cured polyimide article. The lower
aliphatic alcohol employed as a solvent of the thermosetting
solution position is advantageous in that its boiling point is low,
that it is easily removed by evaporation, that it is easily
handled, and that the cost is low. Accordingly, the use of the
lower aliphatic alcohol as the solvent of the thermosetting
solution composition is very advantageous particularly from the
viewpoint of the industrial preparation of the thermosetting
solution composition and the prepreg.
[0012] The present invention resides in a thermosetting solution
composition comprising a biphenyltetracarboxylic acid compound
containing at least 15 mol % of a partial lower aliphatic alkyl
ester of 2,3,3',4'-biphenyltetracarboxylic acid and/or a partial
lower aliphatic alkyl ester of 2,2',3,3'-biphenyltetracarboxylic
acid, an aromatic diamine compound in a molar amount larger than a
molar amount of the biphenyltetracarboxylic acid compound, a
partial lower aliphatic alkyl ester of 4-(2-phenylethynyl)phthalic
acid compound in a molar amount as much as 1.8-2.2 times a molar
amount corresponding to a difference between the molar amount of
the aromatic diamine compound and the molar amount of the
biphenyltetracarboxylic acid compound, and an organic solvent
comprising a lower aliphatic alcohol.
[0013] The lower aliphatic alcohol employed in the invention
includes a mononalent aliphatic alcohol having 1 to 6 carbon atoms.
The representative examples of the lower aliphatic alcohols include
methanol and ethanol. The lower aliphatic alkyl ester include an
ester with a monovalent aliphatic alkyl alcohol having 1 to 6
carbon atoms. The representative examples include methyl ester and
ethyl ester. The partial lower aliphatic alkyl ester means that one
to three carboxyl groups (generally two carboxyl groups) of the
biphenyltetracarboxylic acid form ester bondings with the lower
aliphatic alcohol, and that one carboxyl group of
4-(2-phenylethynyl)phthalic acid forms an ester bonding with the
lower aliphatic alcohol.
[0014] The present invention further resides in a thermosetting
solution composition comprising a biphenyltetracarboxylic acid
compound containing at least 15 mol % of a partial methyl ester of
2,3,3',4'-biphenyltetracarboxylic acid and/or a partial methyl
ester of 2,2',3,3'-biphenyltetracarboxlic acid, an aromatic diamine
compound in a molar amount larger a molar amount of the
biphenyltetracarboxylic acid compound, a partial methyl ester of
4-(2-phenylethynyl)phthalic acid compound in a molar amount as much
as 1.8-2.2 times a molar amount corresponding to a difference
between the molar amount of the aromatic diamine compound and the
molar amount of the biphenyltetracarboxylic acid compound, and an
organic solvent comprising ethanol.
[0015] The preferred embodiments of the thermosetting solution
compositions of the invention are set forth below. [0016] (1) The
lower aliphatic alcohol is methanol, ethanol, or a mixture of these
alcohols. [0017] (2) The lower aliphatic alkyl ester is methyl
ester, ethyl ester, or a mixture of methyl ester and ethyl ester.
[0018] (3) The molar amount of the partial lower aliphatic alkyl
ester of 4-(2-phenylethynyl)phthalic acid compound is as much as
1.95-2.05 times a molar amount corresponding to the difference the
molar amount of the aromatic diamine compound and the molar amount
of the biphenyltetracarboxylic acid compound. [0019] (4) A total
amount of the biphenyltetracarboxylic acid compound, the aromatic
diamine compound, and 2-(2-phenyl-ethynyl)phthalic acid compound is
in the range of 30 to 80 wt. %, per the amount of the solution
composition. [0020] (5) The biphenyltetracarboxylic acid compound
comprises at least 50 molar % of 2,3,3',4'-biphenyltetracarboxylic
acid compound comprising a partial lower aliphatic akyl ester of
2,3,3',4'-biphenyltetracarboxylic acid compound. [0021] (6) The
aromatic diamine compound comprises at least 50 molar % of an
aromatic diamine having one aromatic ring in a molecular structure
thereof. [0022] (7) The aromatic diamine compound comprises
p-phenylenediamine, 1,3-bis(4-aminophenyl)benzene, or a mixture
thereof. [0023] (8) An imidazole compound is contained.
[0024] The present invention furthermore resides in a thermosetting
powder composition comprising a biphenyltetracarboxylic acid
compound containing at least 15 mol % of a partial lower aliphatic
alkyl ester of 2,3,3',4'-biphenyltetracarboxylic acid and/or a
partial lower aliphatic alkyl ester of
2,2',3,3'-biphenyltetracarboxylic acid, an aromatic diamine
compound in a molar amount larger than a molar amount of the
biphenyltetracarboxylic acid compound, and a partial lower
aliphatic alkyl ester of 4-(2-phenylethynyl)phthalic acid compound
in a molar amount as much as 1.8-2.2 times a molar amount
corresponding to a difference between the molar amount of the
aromatic diamine compound and the molar amount of the
biphenyltetracarboxylic acid compound.
[0025] In the above-mentioned thermosetting powder composition, the
partial lower alkyl ester preferably is a partial methyl ester.
[0026] The present invention furthermore resides in a prepreg
comprising a sheet matrix of a reinforcing fiber impregnated with
the thermosetting solution composition of the invention.
[0027] The present invention furthermore resides in a method of
manufacturing a resin article which comprises laminating a plural
number of the prepregs of the invention one on another and heating
the resulting laminate under pressure.
[0028] The thermosetting solution composition of the invention
shows a high solution stability regardless of using an easily
volatile solvent. Therefore, the solvent is easily removed by
evaporation and easily handled when a prepreg is prepared using the
solution composition. In other words, since the lower aliphatic
alcohol employed as the solvent has a low boiling point, removal of
the solvent as well as the by-produced water and compounds are
easily removed by distillation in the procedures of the prepreg and
the cured polyimide article.
[0029] Particularly, when the acid components of the thermosetting
solution composition are in the form of methyl esters, the
resulting prepreg easily gives a cured polyimide article having a
desired form because the prepreg prepared using the thermosetting
solution composition comprising the methyl esters is hardly
deformed in its preparing procedure and shows good moldability.
[0030] In addition, when the solvent of the thermosetting solution
composition is ethanol, the environmental atmosphere formed in the
process of preparing the prepreg and further in the process of the
cured polyimide article less worsen, as compared with the use of
methanol as the solvent. Accordingly, it is most preferred that the
acid components of the thermosetting solution composition are in
the form of methyl esters and further that the solvent is
ethanol.
BRIEF DESCRIPTION OF DRAWINGS
[0031] FIG. 1 is a graph showing results of dynamic viscoelasticity
measurements (indicating relationships between temperature and
complex viscosity).
[0032] FIG. 2 is .sup.1H-NMR spectrum of the thermosetting solution
composition of Example 10(1).
[0033] FIG. 3 is .sup.1H-NMR spectrum of the thermosetting solution
composition of Example 15(1).
[0034] FIG. 4 illustrates an example for the procedure of
manufacturing a cured article from a prepreg.
[0035] FIG. 5 illustrates a phased heating pattern employed in the
procedure of manufacturing a cured article from a prepreg under
vacuum which is performed varying the heating temperature and the
degree of vacuum.
[0036] FIG. 6 illustrates a phased vacuum pattern employed in the
procedure of manufacturing a cured article from a prepreg under
vacuum which is performed varying the heating temperature and the
degree of vacuum.
[0037] FIG. 7 illustrates a phased pressure pattern employed in the
procedure of manufacturing a cured article from a prepreg under
vacuum which is performed varying the heating temperature and the
degree of vacuum.
[0038] FIG. 8 illustrates another phased heating pattern employed
in the procedure of manufacturing a cured article from a prepreg
under vacuum which is performed varying the heating temperature and
the degree of vacuum.
[0039] FIG. 9 illustrates another phased vacuum pattern employed in
the procedure of manufacturing a cured article from a prepreg under
vacuum which is performed varying the heating temperature and the
degree of vacuum.
[0040] FIG. 10 illustrates another phased pressure pattern employed
in the procedure of manufacturing a cured article from a prepreg
under vacuum which is performed varying the heating temperature and
the degree of vacuum.
DETAILED DESCRIPTION OF THE INVENTION
[0041] The monomer compounds required for the preparation of the
thermosetting solution composition of the invention are described
below:
[0042] (1) a biphenyltetracarboxylic acid compound containing at
least 15 mol % of a partial lower aliphatic alkyl ester of
2,3,3',4'-biphenyltetracarboxylic acid and/or a partial lower
aliphatic alkyl ester of 2,2',3,3'-biphenyltetracarboxylic
acid;
[0043] (2) an aromatic diamine compound in a molar amount larger
than a molar amount of the biphenyltetracarboxylic acid compound;
and
[0044] (3) a partial lower aliphatic alkyl ester of
4-(2-phenylethynyl)phthalic acid compound (a portion less than 50
molar % may be not in the form of the alkyl ester) in a molar
amount as much as 1.8-2.2 times a molar amount corresponding to a
difference between the molar amount of the aromatic diamine
compound and the molar amount of the biphenyltetracarboxylic acid
compound.
[0045] The biphenyltetracarboxylic acid compound contains at least
15 molar % (preferably, at least 30 molar %, more preferably, at
least 50 molar %, most preferably at least 80 molar %) of a partial
aliphatic alkyl ester of 2,3,3',4'-biphenyltetracarboxylic acid
and/or a partial aliphatic alkyl ester of
2,2',3,3'-biphenyltetracarboxylic acid. More preferably, the
biphenyltetracarboxylic acid compound comprises a partial aliphatic
alkyl ester of 2,3,3',4'-biphenyltetracarboxylic acid.
[0046] The partial aliphatic alkyl ester of
2,3,3',4'-biphenyltetracarboxylic acid can be prepared by placing
2,3,3',4'-biphenyltetracarboxylic dianhydride in a lower aliphatic
alcohol and heating the resulting mixture to give a solution. The
heating is preferably carried out at a temperature from 40.degree.
C. to the boiling temperature of the alcohol, under refluxing. The
2,3,3',4'-biphenyltetracarboxylic dianhydride is known as the
starting compound for the preparation of an aromatic polyimide
resin. The partial aliphatic alkyl ester of
2,2',3,3'-biphenyltetracarboxylic acid can be prepared by placing
2,2',3,3'-biphenyltetracarboxylic dianhydride in a lower aliphatic
alcohol and heating the resulting mixture to give a solution. The
2,2',3,3'-biphenyltetracarboxylic dianhydride is described in
detail in the aforementioned Japanese Provisional Patent
Publication 2004-331801 A.
[0047] In the thermosetting solution composition, a portion (not
more than 10 molar %) of the partial lower aliphatic alkyl ester of
2,3,3',4'-biphenyltetracarboxylic acid and/or a portion (not more
than 10 molar %) of the partial lower aliphatic alkyl ester of
2,2',3,3'-biphenyltetracarboxylic acid can be replaced with a
partial lower aliphatic alkyl ester of other tetracarboxylic acid.
Examples of the partial lower aliphatic alkyl esters of other
tetracarboxylic acids include a partial lower aliphatic alkyl ester
of 3,3',4,4'-biphenyltetracarboxylic acid compound, a partial lower
aliphatic alkyl ester of 3,3',4,4'-benzophenonetracarboxylic acid
compound, a partial lower aliphatic alkyl ester of pyromellitic
acid compound, and a partial lower aliphatic alkyl ester of
bis(3,4-dicarboxydiphenyl)ether.
[0048] Examples of the aromatic diamine compounds include
p-phenylene diamine, m-phenylene diamine,
1,3-bis(4-aminophenoxy)benzene, and their mixtures. Also employable
are aromatic diamine compounds that are known to be utilized for
the preparation of aromatic polyimide resins. These aromatic
diamine compound are described in detail in the aforementioned
Japanese Provisional Patent Publication 2000-219741 A. Most
preferred aromatic diamine compounds are p-phenylene diamine and
aromatic of p-phenylene diamine and 1,3-bis(4-amiphenyl)benzene,
which are advantageous in preparing a thermosetting solution
composition film of good form stability.
[0049] The aromatic diamine compounds are employed in a molar
amount larger than a molar amount of the biphenyltetracarboxylic
acid cow. For instance, the aromatic diamine compound is employed
1.1 to 2.0 mols, preferably 1.15 to 1.30 mols, per one mole of the
biphenyltetracarboxylic acid compound.
[0050] When a mixture of p-phenylene diamine and
1,3-bis(4-aminophenoxy)benzene is used as the aromatic diamine
compound, the mixture is preferably used in an amount of 1.15 to
1.30 mols per one mole of the biphenyltetracarboxylic acid
compound, and p-phenylene diamine is preferably used in an amount
of 50 to 70 molar % per the total amount of the p-phenylene diamine
and 1,3-bis(4-aminophenoxy)benzene, so that the resulting cured
polyimide article can have enough heat resistance and good molding
characteristics.
[0051] The thermosetting solution composition of the invention
further comprises a partial lower aliphatic alkyl ester of
4-(2-phenylethynyl)phthalic acid in a molar amount as much as
1.8-2.2 times, preferably as much as 1.95-2.05 times, a molar
amount corresponding to a difference between the molar amount of
the aromatic diamine compound and the molar amount of the
biphenyltetracarboxylic acid compound.
[0052] The thermosetting solution composition of the invention
further comprises an organic solvent comprising a lower aliphatic
alcohol (monovalent aliphatic alcohol having 1 to 6 carbon atoms)
as a main component. Preferred are methanol and ethanol. A mixture
of lower aliphatic alcohols can be employed. However, if the
mixture is used, the mixture contains preferably at least 50 vol.
%, more preferably at least 80 vol. %, of methanol or ethanol.
Other low boiling point solvents are also employable in combination
with the lower aliphatic alcohol. However, the other lower boiling
point solvents in the combination preferably is in an amount of 30
vol. % or less.
[0053] The thermosetting solution composition of the invention can
be easily prepared by the step comprising the following thee
steps:
[0054] (1) placing a biphenyltetracarboxylic acid compound
containing at least 15 molar % of 2,3,3',4'-biphenyltetracarboxylic
dianhydride and/or 2,2',3'-biphenyltetracarboxylic dianhydride, and
4-(2-phenylethynyl) phthalic dianhydride in an organic solvent
comprising a lower aliphatic alcohol, to give a suspension;
[0055] (2) heating the suspension to give a solution in which a
lower aliphatic alkyl ester of the biphenyltetracarboxylic acid c
and a lower aliphatic alkyl ester of 4-(2-phenylethynyl)phthalic
acid are dissolved;
[0056] and
[0057] (3) mixing an amotic diamine compound with the solution
obtained in (2) above.
[0058] It has been noted that a thermosetting solution composition
comprises methyl esters of the biphenyltetracarboxylic acid
compound and 4-(2-phenylethynyl)-phthalic acid, a prepreg prepared
from the solution composition shows good form stability in the
procedure of manufacturing a cured polyimide article under pressure
at a high temperature. Accordingly, the lower aliphatic alkyl
esters in the thermosetting solution composition preferably are
methyl esters. However, if environmental pollution caused by
evaporation of methanol in the manufacture of an aromatic polyimide
article from the prepreg should be obviated, the free methanol can
be removed from the prepreg by the following method:
[0059] preparing first a thermosetting solution composition using
methanol;
[0060] drying the prepared thermosetting methanol solution
composition to give a thermosetting powdery composition;
[0061] dissolving the thermosetting powdery composition in ethanol,
to give a thermosetting ethanol solution composition; and
[0062] preparing a prepreg from the thermosetting ethanol solution
composition.
[0063] In the above-mentioned method, the thermosetting powdery
composition is preferably prepared by heating the thermosetting
methanol solution composition to a temperature of not higher than
60.degree. C. The thermosetting powdery composition may contain a
small amount of methanol.
[0064] The prepreg preferably contains a volatile component
including a lower aliphatic alcohol in an amount of 18 to 25 wt. %,
more preferably in an amount of 20 to 22 wt. %.
[0065] The thermosetting solution composition of the invention
preferably further contains an imidazole compound in an amount of
0.01 to 3 wt. %, per the total amount of the reactive compounds
(i.e., biphenyltetracarboxylic acid compound,
4-(2-phenylethynyl)phthalic acid compound, and aromatic diamine
compound). In the preparation of the thermosetting solution
composition, the imidazole compound serves to accelerate the
dissolution of the placed acid components so that the dissolution
can be complete within a shortened period of time. Further, the
imidazole compound serves to accelerate thermosetting of the
prepreg in the procedure that the prepreg is heated under pressure
to manufacture a cured polyimide article. There are no specific
limitation with respect to imidazole compounds. Examples of the
imidazole compounds include known imidazole catalysts such as
2-methylimidazole and 1,2-dimethylimidazole.
[0066] In the thermosetting solution composition of the invention,
the total amount of the aforementioned reactive compounds (i.e.,
biphenyltetracarboxylic acid compound, 4-(2-phenylethynyl)phthalic
acid compound, and aromatic diamine compound) preferably is 30 to
80 wt. %, more preferably 35 to 75 wt. %, more preferably 40 to 75
wt. %, most preferably 45 to 75 wt. %.
[0067] A prepreg is prepared by impregnating a matrix sheet of high
strength fibers with the thermosetting solution composition of the
invention and heating the impregnated matrix sheet for removing a
portion of the solvent by evaporation.
[0068] The prepreg should contain an appropriate amount of a
volatile component and an appropriate amount of a resin component
so that it can be easily handled for the manufacture of the cured
polyimide article. The handling characteristics include
drapeability and tackiness. Accordingly, the matrix sheet can be
impregnated with the thermosetting solution composition by dip
method or cast method, and then heated in a dry air oven to remove
an excessive volatile component, so as to prepare an appropriate
prepreg having a resin content (Rc) of 35 to 55 wt. % and a
volatile content (Vc) of 10 to 25 wt. %. The heating procedure is
generally carried out at a temperature in the range of 40 to
150.degree. C., for 0.5 to 30 min.
[0069] The matrix sheet comprises known high strength fibers such
as carbon fibers, aramide fibers, glass fibers, and ceramic fibers
such as titanium dioxide fibers.
[0070] The prepreg of the invention can be heated to give a cured
polyimide article having Tg of higher than 300.degree. C. (or
showing no Tg at temperatures of 300.degree. C. or lower).
[0071] The prepreg preferably is in the form of a roll and is
preferably coated on both surfaces with a covering sheet such as
polyethylene terephthalate sheet and paper sheet for its storage
and transportation.
[0072] The prepreg can be processed to give a cured resin article
by a variety of known methods. For instance, a roll of prepreg is
cut to give plural sheets having the desired size. The plural
prepreg sheets (for instance, from several sheets to sheets of more
than a hundred) are laminated one on another, and the formed
prepreg laminate is heated under pressure by means of a hot press.
In the procedure of heating under pressure, the thermosetting
composition gives an aromatic polyimide article through thermal
imidation reaction and curing reaction.
[0073] For instance, the laminate of prepregs is heated under
pressure in the manner as illustrated in FIG. 4. In more detail,
the laminate of prepregs 11 are placed between a pair of air
permeable sheets (such as polyethylene terephthalate sheets and
glass sheets) 12a,12b. On each of the air permeable sheets 12a,12b
is placed a release film 13a,13b. Thus prepared laminate is placed
between a pair of heat-resistant non-woven cloths (sponge
materials) 14a,14b, and then is encase in a heat-resistant bag 15.
The heat-resistant bag 15 is then sealed at the open end 16, for
instance, by heat sealing. The inner space of the bag 15 is
evacuated by withdrawing air through the evacuation pipe 17 by
vacuum pump, while the enclosed laminate is heated under pressure.
In the procedure of evacuation and heating under pressure, it is
preferred to vary the degree of vacuum and temperature according
the patterns illustrated in FIGS. 5 to 10.
[0074] The present invention is further described by the following
non-limiting examples.
[0075] In the following examples, the measured values and
calculated values are obtained in the following manners. [0076] (1)
Total reactive component content in solution Total reactive
component content (%)100.times.[amounts(g) of the employed reactive
components]/[amounts(g) of the employed reactive components+amount
(g) of the solvent] [0077] (2) Solution viscosity
[0078] The solution viscosity was determined at 25+ C. by means of
an E-type viscometer (available from Tokyo Measuring aratus Co.,
Ltd.). [0079] (3). Glass transition temperature (Tg) of cured resin
article
[0080] For the measurement, the cured resin article is heated in a
nitrogen gas by means of SSC5200-DSC-3200 (available from
Seiko-Instrument Co., Ltd.) at a temperature elevation rate of
200.degree. C./min. [0081] (4) Linear expansion coefficient of
cured resin article
[0082] For the measurement, the cured resin article is heated from
50.degree. C. to 250.degree. C. in a nitrogen gas by means of TM-50
(available from Shimazu Seisa)s Co., Ltd.) at a temperature
elevation rate of 5.degree. C./min. [0083] (5) Volatile content
(Vc) and Resin content (Rc) Vc(%)=100.times.[amount (g) of uncured
prepreg-amount (g) of prepreg after heating at 370.degree. C. for
one hour]/[amount (g) of uncured prepreg]
Rc(%)=100.times.[amount(g) of prepreg after heating at 370.degree.
C. for one hour-amount(g) of matrix sheet]/[amount(g) of prepreg
after heating at 370.degree. C. for one hour] [0084] (6) Complex
viscosity of prepreg
[0085] A dynamic viscoelasticity is measured in a nitrogen
atmosphere by means of a melt dynamic viscoelastometer (available
from T. A. Instrument Japan Co., Ltd.) at a temperature elevation
rate of 2.degree. C./min. [0086] (7) Thermal decomposition
temperature of resin article
[0087] The heat treated resin article is heated in TG/DTA 6300
(available from S. I. I. Nanotechnology Co., Ltd) at a temperature
elevation rate of 5.degree. C./min. The temperature at which a
weight loss of 5 wt. % is observed is recorded as the thermal
decomposition temperature. [0088] (8) Measurement of .sup.1H-NMR
spectrum
[0089] The .sup.1H-NMR spectrum was measured at a resonance
frequency of 400 MHz in a deuterated methanol by means of a nuclear
magnetic spectrometer EX-400 type, FT-NMR (available from JEOL,
Ltd.).
[0090] In the following examples, the following matter components
(i.e., reactive components) were employed:
[0091] a-BPDA: 2,3,3',4'-biphenyltetracarboxylic dianhydride
[0092] s-BPMA: 3,3',4,4'-biphenyltetracarboxylic dianhydride
[0093] PEPA: 4-(phenylethynyl)phthalic anhydride
[0094] TPE-R: 1,3-bis(4-aminophenoxy)benzene
[0095] PPD: p-phenylene diamine
[0096] m-phenylene diamine
EXAMPLE 1
(1) Preparation of Thermosetting Solution Composition
[0097] In a four-necked 100 mL volume separable flask equipped with
a stirrer, a reflux condenser and a nitrogen gas inlet were placed
11.77 g (0.0400 mol) of a-BPDA, 4.97 g (0.0200 mol) of PEPA, and
13.54 g of ethanol in a nitrogen gas stream. The resulting mixture
was stirred under reflux for 5 hours to give a homogeneous
solution. The solution was then cooled to room temperature. To the
solution were added under stirring 6.58 g (0.0225 mol) of TPE-R and
2.97 g (0.0275 mol) of PPD. The resulting mixture was heated at
60.degree. C. for 60 mixtures to give a homogeneous solution
(thermosetting solution composition).
[0098] The homogeneous solution was spread over a polyamide film
(Upilex 125S, available from Ube Industries, Ltd.) and successively
heated at 80.degree. C. for 30 min., 135.degree. C. for 30 min.,
180.degree. C. for 30 min., 250.degree. C. for 30 min., 300.degree.
C. for 30 muin., and 370.degree. C. for 60 min., to give a clear
resin film having a thickness of approx. 0.1 mm.
[0099] The viscosity of the homogeneous solution and Tg of the
resin film are set forth in Table 1.
(2) Preparation of Prepreg
[0100] The above-mentioned homogeneous solution (thermosetting
solution composition) was spread over a polyethylene terephthalate
(PET) film to form a solution film. On the solution film was placed
a carbon fiber cloth (FAW 198 g/m.sup.2, plain cloth, T300-3K,
available from Toray Corp.) having a size of 80 mm.times.100 mm.
Thus prepared laminate was placed on a hot plate heated to
40.degree. C. under the condition that the PET film was brought
into contact with the hot plate. On the hot plate, the upper
surface of the carbon fiber cloth was lightly pressed onto the PET
film so that the cloth could be impregnated with the solution.
Subsequently, the solution-impregnated carbon cloth was separated
from the PET film, and dried by hanging it for 3 minutes in a hot
air oven heated to 100.degree. C. The dry carbon cloth was taken
out of the oven, placed between a pair of PET film (thickness: 25
.mu.m), and pressed at a pressure of 0.1 MPa for one minute by
means of a hot press heated to 80.degree. C. Thus, a prepreg was
prepared.
(3) Manufacture of Cured Resin Sheet
[0101] The prepreg was successively heated at 135.degree. C. for 30
min., 180.degree. C. for 30 min., 250.degree. C. for 30 min.,
300.degree. C. for 30 min., and 370.degree. C. for 60 min., to
manufacture a cured resin sheet.
[0102] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc and Rc
are set forth in Table 2.
EXAMPLE 2
(1) Preparation of Thermosetting Solution Composition
[0103] The procedures of Example 1-(1) were repeated except that
the TPE-R, PPD and ethanol were used in amounts of 4.39 g (0.0150
mol), 3.78 g (0.0350 mol), and 11.72 g, respectively, to give a
homogeneous solution (thermosetting solution composition). Further,
the homogeneous solution was processed in the same manner as in
Example 1-(1), to give a clear resin film (thickness: approx. 0.1
mm).
[0104] The viscosity of the homogeneous solution and Tg of the
resin film are set forth in Table 1.
(2) Preparation of Prepreg
[0105] The procedures of Example 1-(2) were repeated using the
homogeneous solution prepared in (1) above, to prepare a
prepreg.
[0106] The prepreg was subjected to measurement of dynamic
viscoelasticity. The measured viscoelasticity is shown in FIG.
1.
(3) Manufacture of Cured Resin Sheet
[0107] The procedures of Example 1-(3) were repeated using the
prepreg prepared in (2) above, to manufacture a cured resin
sheet.
[0108] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc and Rc
are set forth in Table 2.
EXAMPLE 3
(1) Preparation of Thermosetting Solution Composition
[0109] The procedures of Example 1-(1) were repeated except that
the a-BPDA, s-BPDA, PEPA and ethanol were used in amounts of 5.89 g
(0.0200 mol), 5.89 g (0.0200 mol), 4.97 g (0.0200 mol), and 12.37
g, respectively, to give a homogeneous solution (thermosetting
solution composition). Further, the homogeneous solution was
processed in the same manner as in Example 1-(1), to give a clear
resin film (thickness: approx. 0.1 mm).
[0110] The viscosity of the homogeneous solution and Tg of the
resin film are set forth in Table 1.
(2) Preparation of Prepreg
[0111] The procedures of Example 1-(2) were repeated using the
homogeneous solution prepared in (1) above, to prepare a
prepreg.
(3) Manufacture of Cured Resin Sheet
[0112] The procedures of Example 1-(3) were repeated using the
prepreg prepared in (2) above, to manufacture a cured resin
sheet.
[0113] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc and Rc
are set forth in Table 2.
EXAMPLE 4
(1) Preparation of Thermosetting Solution Composition
[0114] The procedures of Example 1-(1) were repeated except that
the a-BPDA, s-BPnM, PEPA and ethanol were used in amounts of 3.53 g
(0.0120 mol), 8.24 g (0.0280 mol), 4.97 g (0.0200 mol), and 11.27
g, respectively, to give a homogeneous solution (thermosetting
solution composition). Further, the homogeneous solution was
processed in the same manner as in Example 1-(1), to give a clear
resin film (thickness: approx. 0.1 mm).
[0115] The viscosity of the homogeneous solution and Tg of the
resin film are set forth in Table 1.
(2) Preparation of Prepreg
[0116] The procedures of Example 1-(2) were repeated using the
homogeneous solution prepared in (1) above, to prepare a
prepreg.
(3) Manufacture of Cured Resin Sheet
[0117] The procedures of Example 1-(3) were repeated using the
prepreg prepared in (2) above, to manufacture a cured resin
sheet.
[0118] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc and Rc
are set forth in Table 2.
EXAMPLE 5
(1) Preparation of Thermosetting Solution Composition
[0119] The procedures of Example 1-(1) were repeated except that
the TPE-R, MPD (in place of PPD) and ethanol were used in amounts
of 2.07 g (0.0070 mol), 4.66 g (0.0430 mol) and 12.64 g,
respectively, to give a homogeneous solution (thermosetting
solution composition). Further, the homogeneous solution was
processed in the same manner as in Example 1-(1), to give a clear
resin film (thickness: approx. 0.1 mm).
[0120] The viscosity of the homogeneous solution and Tg of the
resin film are set forth in Table 1.
(2) Preparation of Prepreg
[0121] The procedures of Example 1-(2) were repeated using the
homogeneous solution prepared in (1) above, to prepare a
prepreg.
(3) Manufacture of Cured Resin Sheet
[0122] The procedures of Example 1-(3) were repeated using the
prepreg prepared in (2) above, to manufacture a cured resin
sheet.
[0123] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc and Rc
are set forth in Table 2.
[0124] In this example, the following cured resin sheet was further
manufactured.
(4) Manufacture of Cured Resin Sheet
[0125] A carbon fiber cloth (FAW 198 g/m.sup.2, plain cloth,
T300-3K, available from Toray Corp.) was placed in a dry air oven
parged with a nitrogen gas, and heated at 350.degree. C. for 30
minutes. By measuring the weight loss of the carbon fiber cloth
after the heat treatment, it was confirmed that 0.7 wt. % of a
sizing agent was removed.
[0126] The procedures of Example 5-(2) and 5-(3) were repeated
using the heat treated carbon fiber cloth and the homogeneous
solution of Example 5-(1), to prepare a prepreg and then
manufacture a cured resin sheet.
[0127] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc was 15
wt. % and Rc was 39 wt. %.
(5) Manufacture of Cured Resin Sheet
[0128] The procedures of Example 5-(2) and 5-(3) were repeated
using Tirano fiber cloth (titanium dioxide fiber cloth, FAW 328
g/m.sup.2, plain cloth, PM-S17E08PX, available from Ube Industries,
Ltd.) and the homogeneous solution of Example 5-(1), to prepare a
prepreg and then manufacture a cured resin sheet.
[0129] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc was 16
wt. % and Rc was 39 wt. %.
(6) Manufacture of Cured Resin Sheet
[0130] Ten g (10 g) of the homogeneous solution prepared in Example
5-(1) was diluted with 2.5 g of methyl ethyl ketone. The resulting
solution was a homogeneous solution.
[0131] The procedures of Example 5-(2) and 5-(3) were repeated
using the above-mentioned homogeneous solution, to prepare a
prepreg and then manufacture a cured resin sheet.
[0132] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc was 15
wt. % and Rc was 39 wt. %.
EXAMPLE 6
(1) Preparation of Thermosetting Solution Composition
[0133] The procedures of Example 1-(1) were repeated using 11.06 g
(0.0376 mol) of a-BPDA, 16.55 g (0.0667 mol) of PEPA, 10.38 g
(0.0355 mol) of TPE-R, 3.84 g (0.0355 mol) of MPD, and 17.09 g of
ethanol, to give a homogeneous solution (thermosetting solution
composition). Further, the homogeneous solution was processed in
the same manner as in Example 1-(1), to give a clear resin film
(thickness: approx. 0.1 mm).
[0134] The viscosity of the homogeneous solution and Tg of the
resin film are set forth in Table 1.
(2) Preparation of Prepreg
[0135] The procedures of Example 1-(2) were repeated using the
homogeneous solution prepared in (1) above, to prepare a
prepreg.
(3) Manufacture of Cured Resin Sheet
[0136] The procedures of Example 1-(3) were repeated using the
prepreg prepared in (2) above, to manufacture a cured resin
sheet.
[0137] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc and Rc
are set forth in Table 2.
EXAMPLE 7
(1) Preparation of Thermosetting Solution Composition
[0138] The procedures of Example 1-(1) were repeated using 15.59 g
(0.0530 mol) of a-BPDA, 23.33 g (0.0940 mol) of PEPA, 14.62 g
(0.0500 mol) of TPE-R, 2.70 g (0.0250 mol) of PPD, 2.70 g (0.0250
mol) of MED, and 25.26 g of ethanol, to give a homogeneous solution
(thermosetting solution composition). Further, the homogeneous
solution was processed in the same manner as in Example 1-(1), to
give a clear resin film (thickness: approx. 0.1 mm).
[0139] The viscosity of the homogeneous solution and Tg of the
resin film are set forth in Table 1.
(2) Preparation of Prepreg
[0140] The procedures of Example 1-(2) were repeated using the
homogeneous solution prepared in (1) above, to prepare a
prepreg.
(3) Manufacture of Cured Resin Sheet
[0141] The procedures of Example 1-(3) were repeated using the
prepreg prepared in (2) above, to manufacture a cured resin
sheet.
[0142] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc and Rc
are set forth in Table 2.
EXAMPLE 8
(1) Preparation of Thermosetting Solution Composition
[0143] The procedures of Example 1-(1) were repeated except that
TPE-R was not used, and that the PPD and ethanol were used in
amounts of 5.41 g (0.0500 mol) and 14.46 g, respectively, to give a
homogeneous solution (thermosetting solution composition). Further,
the homogeneous solution was processed in the same manner as in
Example 1-(1), to give a clear resin film (thickness: approx. 0.1
mm).
[0144] The viscosity of the homogeneous solution and Tg of the
resin film are set forth in Table 1.
(2) Preparation of Prepreg
[0145] The procedures of Example 1-(2) were repeated using the
homogeneous solution prepared in (1) above, to prepare a
prepreg.
(3) Manufacture of Cured Resin Sheet
[0146] The procedures of Example 1-(3) were repeated using the
prepreg prepared in (2) above, to manufacture a cured resin
sheet.
[0147] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc and Rc
are set forth in Table 2.
EXAMPLE 9
(1) Preparation of Thermosetting Solution Composition
[0148] In a four-necked 2,000 mL volume separable flask equipped
with a stirrer, a reflux condenser and a nitrogen gas inlet were
placed 294.22 g (1.000 mol) of a-BPDA, 124.12 g (0.500 mol) of
PEPA, and 415.06 g of methanol in a nitrogen gas stream. The
resulting mixture was stirred under reflux for 5 hours to give a
homogeneous solution (the mixture turned into a homogeneous
solution within approx. 3 hours, but the stirring under reflux was
continued for additional 2 hours. The solution was then cooled to
room temperature. To the solution were added under stirring 109.63
g (0.375 mol) of TPE-R and 94.62 g (0.875 mol) of PPD. The
resulting mixture was heated at 60.degree. C. for 60 minutes to
give a homogeneous solution (thermosetting solution composition).
Further, the homogeneous solution was processed in the same manner
as in Example 1-(1), to give a clear resin film (thickness: approx.
0.1 mm).
[0149] The viscosity of the homogeneous solution and Tg of the
resin film are set forth in Table 1.
(2) Preparation of Prepreg
[0150] The above-mentioned homogeneous solution (thermosetting
solution composition) was spread over a polyethylene terephthalate
(PET) film to form a solution film. On the solution film was placed
a carbon fiber cloth (FAW 320 g/m.sup.2, plain cloth, T800-12K,
available from Toray Corp.) having a size of 320 mm.times.320 mm.
Thus prepared laminate was placed on a hot plate heated to
40.degree. C. under the condition that the PET film was brought
into contact with the hot plate. On the hot plate, the upper
surface of the carbon fiber cloth was lightly pressed onto the PET
film so that the cloth could be impregnated with the solution.
Subsequently, the solution-impregnated carbon cloth was separated
from the PET film, and dried by hanging it for 3 minutes in a hot
air oven heated to 90.degree. C. The dry carbon cloth was taken out
of the oven, placed between a pair of PET film (thickness: 25
.mu.m), and pressed at a pressure of 0.1 MPa for one minute by
means of a hot press heated to 80.degree. C. Thus, a prepreg was
prepared.
[0151] Thus prepared prepreg showed good tackiness and
drapeability.
[0152] The prepreg was subjected to measurement of dynamic
viscoelasticity. The measured viscoelasticity is shown in FIG.
1.
(3) Manufacture of Cured Resin Sheet
[0153] The prepreg was successively heated at 135.degree. C. for 30
min., 180.degree. C. for 30 min., 250.degree. C. for 30 min.,
300.degree. C. for 30 min., and 370.degree. C. for 60 min., to
manufacture a cured resin sheet.
[0154] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc and Rc
are set forth in Table 2.
EXAMPLE 10
(1) Preparation of Thermosetting Solution Composition
[0155] In the same separable flask as that described in Example
9-(1) were placed 294.22 g (1.000 mol) of a-BPDA, 124.12 g (0.500
mol) of PEPA, 1.25 g of 2-methylimidazole, and 415.06 g of methanol
in a nitrogen gas stream. The resulting mixture was stirred under
reflux for 3 hours to give a homogeneous solution (the mixture
turned into a homogeneous solution within approx. 1 hour, but the
stirring under reflux was continued for additional 2 hours. The
solution was then cooled to room temperature. To the solution were
added under stirring 109.63 g (0.375 mol) of TPE-R and 94.62 g
(0.875 mol) of PPD. The resulting mixture was heated at 60.degree.
C. for 60 minutes to give a homogeneous solution (thermosetting
solution composition).
[0156] The homogeneous solution was subjected to measurement of
.sup.1-NMR spectrum. The .sup.1H-NMR spectrum is seen in FIG.
2.
[0157] Further, the homogeneous solution was processed in the same
manner as in Example 1-(1), to give a clear resin film (thickness:
approx. 0.1 mm).
[0158] The viscosity of the homogeneous solution and Tg of the
resin film are set forth in Table 1.
[0159] The other physical characteristics of the resin film are set
forth below:
[0160] tensile strength: 127 MPa (at 23.degree. C., according to
ASTM D 882)
[0161] tensile modulus: 2.8 GPa (at 23.degree. C., according to
ASTM D 882)
[0162] breaking extension: 13% (at 23.degree. C., according to ASTM
D 882)
[0163] water absorption: 2.2t (at 23.degree. C., saturation
absorption, according to ASTM D 570)
[0164] thermal decomposition temperature: 563.degree. C.
[0165] linear expansion coefficient: 51 ppm
(2) Preparation of Prepreg
[0166] The procedures of Example 1-(2) were repeated using the
homogeneous solution prepared in (1) above, to prepare a
prepreg.
(3) Manufacture of Cured Resin Sheet
[0167] The procedures of Example 1-(3) were repeated using the
prepreg prepared in (2) above, to manufacture a cured resin
sheet.
[0168] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc and Rc
are set forth in Table 2.
EXAMPLE 11
(1) Preparation of Thermosetting Solution Composition
[0169] In the same separable flask as that described in Example
9-(1) were placed 294.22 g (1.000 mol) of a-BPDA, 124.12 g (0.500
mol) of PEPA, 1.25 g of 2-methylimidazole, and 415.06 g of
n-propanol in a nitrogen gas stream. The resulting mixture was
stirred under reflux for 3 hours to give a homogeneous solution
(the mixture turned into a homogeneous solution within approx. 1
hour, but the stirring under reflux was continued for additional 2
hours. The solution was then cooled to room temperature. To the
solution were added under stirring 109.63 g (0.375 mol) of TPE-R
and 94.62 g (0.875 mol) of PPD. The resulting mixture was heated at
60.degree. C. for 60 minutes to give a homogeneous solution
(thermosetting solution composition). Further, the homogeneous
solution was processed in the same manner as in Example 1-(1), to
give a clear resin film (thickness: approx. 0.1 mm).
[0170] The viscosity of the homogeneous solution and Tg of the
resin film are set forth in Table 1.
(2) Preparation of Prepreg
[0171] The procedures of Example 9-(2) were repeated except that
the homogeneous solution prepared in (1) above was used, and the
drying procedure was performed at 100.degree. C. for 15 minutes, to
prepare a prepreg.
[0172] Thus prepared prepreg showed good tackiness and
drapeability.
[0173] The prepreg was subjected to measurement of dynamic
viscoelasticity. The measured viscoelasticity is shown in FIG.
1.
(3) Manufacture of Cured Resin Sheet
[0174] The procedures of Example 9-(3) were repeated using the
prepreg prepared in (2) above, to manufacture a cured resin
sheet.
[0175] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. The determined Vc and Rc
are set forth in Table 2. TABLE-US-00001 TABLE 1 Monomer Solution
Tg of cured content(wt. %) viscosity(poise) sheet (.degree. C.)
Example 1 66 105 323 Example 2 68 112 365 Example 3 68 107 319
Example 4 70 106 321 Example 5 65 107 342 Example 6 71 115 317
Example 7 70 110 336 Example 8 60.5 106 *1 Example 9 60 2.0 357
Example 10 60 2.2 357 Example 11 60 113 357 Remarks: The monomer
content means the concentration of the reactive components in the
thermosetting solution composition. *1 means that no clear Tg was
observed at temperatures below 400.degree. C.
[0176] TABLE-US-00002 TABLE 2 Homogeneous Vc Rc solution (wt. %)
(wt. %) Example 1 16 39 Example 2 15 39 Example 3 16 40 Example 4
15 39 Example 5 15 38 Example 6 15 39 Example 7 16 39 Example 8 15
39 Example 9 13 41 Example 10 13 41 Example 11 14 36
[0177] The following examples 12 and 13 describe the preparation of
the cured resin article in the manner as illustrated in FIG. 4.
EXAMPLE 12
[0178] The prepreg prepared in Example 5-(2) was cut to give 16
prepreg sheets, each having a size of 50 mm.times.60 mm. The 16
prepreg sheets were laminated one on another, and thus prepared
laminate was placed in the heat-resistant bag (as is illustrated in
FIG. 4). The open end of the bag was sealed by heat sealing, and
the bag was placed in a hot press. The laminate in the bag was so
heated under pressure, under the conditions of the degree of vacuum
in the bag and the heating temperature that the historical curve in
FIGS. 5 to 7 could be satisfied. Thus, a cured resin article was
manufactured.
[0179] The cured resin article was subjected to measurement of the
interlaminar shear strength at 23.degree. C. according to ASTM
D2344, to give a shear strength of 60 MPa. The cured resin article
was further subjected to detection of flaw by means of a supersonic
flaw detector. No significant flaw was detected.
EXAMPLE 13
[0180] The prepreg prepared in Example 9-(2) was cut to give 12
prepreg sheets, each having a size of 300 mm.times.300 mm. The 12
prepreg sheets were laminated one on another, and thus prepared
laminate was placed in the heat-resistant bag (as is illustrated in
FIG. 4). The open end of the bag was sealed by heat sealing, and
the bag was placed in a hot press. The laminate in the bag was so
heated under pressure, under the conditions of the degree of vacuum
in the bag and the heating temperature that the historical curve in
FIGS. 8 to 10 could be satisfied. Thus, a cured resin article was
manufactured.
[0181] The cured resin article contained the carbon fiber matrix of
59 vol. % and a void volume of 0.5 vol. %. The carbon fiber matrix
content and void volume were determined according to ASTM
D3171.
[0182] Then, the cured resin article was subjected to detection of
flaw by mean of a supersonic flaw detector. No significant flaw was
detected.
[0183] The physical characteristics of the cured resin article are
set forth below:
[0184] Flexural strength (according to AST D790): [0185] 815 MPa
(at 23.degree. C.), 479 MPa (at 288.degree. C.)
[0186] Flexural modulus (according to ASTM D790): [0187] 61.9 GPa
(at 23.degree. C.), 62.0 GPa (at 288.degree. C.)
[0188] Interlaminar shear strength (according to ASTM D2344): 68.8
MPa (at 23.degree. C.), 38.2 MPa (at 288.degree. C.)
[0189] The cured resin article was further heated at 357.degree. C.
for 6 hours in an hot air oven. Thus heated article was subjected
to measurement of the interlaminar shear strength. The results were
set forth below:
[0190] Interlaminar shear strength (according to ASTM D2344): 49.6
MPa (at 23.degree. C.), 33.9 Ma (at 288.degree. C.)
[0191] The following examples 14 and 15 describe the preparation of
a thermosetting powder composition, the preparation of a
thermosetting solution composition from the powdery composition,
the preparation of a prepreg from the prepared thermosetting
solution composition, and the manufacture of a cured resin
article.
EXAMPLE 14
(1) Preparation of Thermosetting Powder Composition
[0192] 40.00 g of the homogeneous solution (thermosetting solution
composition) prepared in Example 10-(1) was placed in a 500 mL
volume eggplant-type flask. The flask was dipped in a water bath
heated to 40.degree. C., and the flask was evacuated for 3 hours by
an evaporator to remove methanol. Thus, a powdery composition
(thermosetting powder composition) was prepared.
[0193] The powdery composition was examined in the following
manner.
[0194] A polyimide film having a size of 300 mm.times.300 mm and a
air permeable tetrafluoroethylene/glass sheet having the same size
and a thickness of 2 mm is placed on a stainless steel plate having
the same size in order. On the air permeable sheet was placed a
stainless steel frame (width 50 mm, length 100 mm, thickness 3 mm).
The powder composition was placed in the frame. On the frame were
placed in order the same air permeable tetrafluoroethylene/glass
sheet, polyimide film and stainless steel plate so as to cover the
frame. The frame with the covering sheets was placed in a high
temperature vacuum press (KVHC-PRESS, available from Kitagawa Seiki
Co., Ltd.) and heated from room temperature to 250.degree. C. for 3
hours and further at 250.degree. C. for 2 hours. The vacuum press
was evacuated to make the inner space a vacuum of 2 Torr for 30
minutes. Thereafter, the powdery composition in the frame was
heated to 370.degree. C. for 24 mites under 5 MPa, and kept under
the condition for one hour. The composition was then cooled in
vacuum to 30.degree. C. under pressure, to give a resin plate
(width 50 mm, length 100 mm, thickness 3 mm).
[0195] The resin plate was cut to a piece of 50 mm.times.50 mm, and
subjected to the following measurement of heat loss.
[0196] Weight loss after heat treating: [0197] 0.60% (300.degree.
C. 500 hours, in air) [0198] 0.15% (275.degree. C., 500 hours, in
air)
EXAMPLE 15
[0198] (1) Preparation of Thermosetting Powder Composition
[0199] 20.00 g of the homogeneous solution (thermosetting solution
composition) prepared in Example 10-(1) was placed in a 300 mL
volume eggplant-type flask. The flask was dipped in a water bath
heated to 40.degree. C., and the flask was evacuated for 3 hours by
an evaporator to remove methanol. Thus, 14.2 g of a powdery
composition (thermosetting powder composition) was prepared.
[0200] The homogeneous solution was subjected to measurement of
.sup.1H-NMR spectrum. The .sup.1H-NMR spectrum is seen in FIG.
3.
(2) Preparation of Thermosetting Solution Composition from
Thermosetting Powder Composition
[0201] In 4.59 g of ethanol as dissolved 13.78 g of the powdery
composition (thermosetting powder composition) obtained in (1)
above, to give a homogeneous solution (thermosetting solution
composition).
(3) Preparation of Prepreg
[0202] A prepreg was prepared in the manner as described in Example
1-(2) using the ethanolic solution composition prepared in (2)
above.
[0203] Thus prepared prepreg showed good tackiness and
drapeability.
[0204] The prepreg was subjected to measurement of dynamic
viscoelasticity. The measured viscoelasticity is shown in FIG.
1.
(4) Manufacture of Cured Resin Sheet
[0205] The procedures of Example 1-(3) were repeated using the
prepreg prepared in (3) above, to manufacture a cured resin
sheet.
[0206] The volatile content (Vc) and resin content (Rc) were
determined from the data measured in the procedure of manufacturing
the cured resin sheet from the prepreg. It was determined that Vc
was 15% and Rc was 41%.
(5) Concentration Dependency and Temperature Dependency of Solution
Viscosity of Thermosetting Solution Composition
[0207] The thermosetting powder composition prepared in Example
14-(1) was dissolved in ethanol to give homogeneous solutions
having different concentrations. The relationship between the
concentration of the solution and the solution viscosity is set
forth below. TABLE-US-00003 Concentration Solution viscosity Imide
content of powder(wt. %) (30.degree. C., poise) (wt. %) 50 0.3 40
62.5 1.9 50 75 54 60
Remarks: The imide content was determined by the following method:
The powdery composition (thermosetting powder composition) was
processed to give a fully imidized product which was then heated at
250.degree. C. for 30 minutes to completely remove methanol; the
weight of the imidized product was measured, and a ratio of weight
loss from the powder composition to the imidized product was
calculated. The imide content was calculated by the following
equation: Imide content (%)=Concentration of powder
(%).times.(1-ratio of weight loss)
[0208] The thermosetting solution composition (concentration of
62.5 wt. % in ethanol) prepared from the thermosetting powder
composition in Example 14-(1) was subjected to measurement of
temperature dependency of solution viscosity. The results are set
forth below. TABLE-US-00004 Temperature (.degree. C.) Solution
viscosity (poise, 30.degree. C.) 20 4.5 30 1.9 40 1.0 50 0.6
COMPARISON EXAMPLE 1
[0209] The procedures of Example 1-(1) were repeated except for
replacing a-BPDA (0.0400 mol) with s-BPDA (11.77 g, 0.0400 mol), to
prepare a homogeneous solution. A portion of the homogeneous
solution was spread on a polyimide film in the same manner as in
Example 1-(1) and heated at 80.degree. C. for 30 min., 135.degree.
C. for 30 min., 180.degree. C. for 30 min., 250.degree. C. for 30
min., 300.degree. C. for 30 min., and 370.degree. C. for 60 min. In
the course of the heating, the solution film turned into an opaque
and brittle film.
* * * * *