Note: Descriptions are shown in the official language in which they were submitted.
~27~
-- 1 --
29,825
HEAT CURABLE POLYMERS WHIC~ CONTAIN
IMIDE GROUPS AND PROCESS
The present invention relates to new heat-
stable resins based on three-dimensional polyimides.
BACKGROUND OF THE INVENTION
Polyimide resins are particularly useful as
aerospace adhesives and composites because of their
remarkable mechanical strength, high service temperature,
low moisture sensitivity, and enhanced processability.
Polyimides are used as components in the man-
!. ufacture of polyaddition products and polymerization
products. Thus, for example, the polyaddition reaction
of bis-maleimides with primary diamines and the curing
of these pre-adducts by polymerization by the action of
heat are described in French Patent Number 1,555,564.
However, this process is not easily used in the production
o ~ 2'7~5~
of composites because they are inherently brittle mater-
ials and have less than optimum handling characteristics
because tapes and fabrics impregnated with them have
poor tack and drape characteristics.
Polyaddition products of bis-maleimides and
alkenylphenols and/or alkenylphenol ethers are claimed
in U.S. Patent No. 4,100,1~0. Such materials, however,
while stable at ordinary temperatures, produce molded
articles somewhat deficient in hot/wet strength and
resistance to thermal aging.
Heat-curable three-dimensional compositions of
bis-maleimides, polyamines and allyl esters are disclosed
in German Published Patent Specification 2,131,735. But
these have short processing times, making them unsuitable
for the manufacture of composites and adhesives. Other
heat-curable three-dimensional polyimides are known,
e.g., from U.S. 4,454,283, which discloses bis-maleimides,
polyamines and polyvinylaromatics. These compositions
are toxic, and the ultimate impact resistance is poor,
as is resistance to edge delamination.
It has now been discovered that polymers which
contain imide groups and are based on polymaleimides,
can be provided and that these do not exhibit the dis-
advantages of the polyadducts based on polymaleimide,
in the present state of the art. Moreover, these new
compositions can be manuEactured without difficulty,
they have long pot lives, and they produce heat cured
articles with superior physical properties, particular-
ly impact resistance, and strength retention after hot/
wet exposure, resistance to edge delamination and to the
a~ver.se effects of therma~ aging.
- 3 -
SU~I~AI'Y 0~ V~ 0
According to the present invention, there are
provided compositions which are stable on storage and
can be cured by the action of heat, said compositions
comprising
(a) a heat curable polyimide resin containing,
per average molecule, at least two groups of the formula
~C~
D \ / N - -
CO
directly attached to carbon atoms, wherein D is
CH C - CH = C - CH -
3 11 2 1 ll
CH- CH- CH -
or a mixture thereof; and
(b) a heat-activated curing agent for said
polyimide resin comprising, in combination,
(i) a polyamine of the formulae:
G (NH2) or
NH NH NH
~-- R ~ R-
wherein G denotes a y-valent organic radical having 2 to
40 carbon atoms and y is an integer of 2 to 4, each R
represents a divalent hydrocarbon radical obtained by
3S removing the oxygen atom of an aldehyde or ketone having
~z~
o
1 to 8 carbon atoms, and m is a number of from 0.1 to 2
and
(ii) an alkenylphenol or an ether thereof,
in amounts such that if N represents the number of
moles of polyimide employed, N represents the number of
moles of polyamine employed and N represents the number
of moles of alkenylphenol or ether thereof employed, the
ratio
Nl Nl
or
2 3 2(m + 2)N2 + N3
is greater than 0.3,-preferably from 0.3 to 10, y or m
being defined as above.
In a preferred aspect, component (a) comprises
a mixture of heat curable polyimide resins of the formula
/ CO~ / CO
D ~ ~ N Z - N ~ / D
CO CO
wherein D is
CE~ - C - 2 1 or ICH -
CH- CH- CH-
or a mixture thereof, and Z is the residue of at least
one aromatic diamine and in the minor proportion of the
mixture, Z is the residue of an aliphatic diamine.
In another principal aspect, the present in-
vention provides a process for the preparation of a
cross-linked polymer which is stable on storage and can
be cured by the action of heat which comprises
o ~ 5~
(a) a polyimide of the formula
R CO CO / R
S \C \ / \C
N-A-N ll
/ \ / CH
CO CO
wherein R is hydrogen or methyl, and
A is a divalent radical of the formula
~ (R ) ~
in which R is selected from the group consisting of
-CH -,
ICH3
C
CH
-SO2-, -SO-, -S- and -O-, and n is 0 or 1; or a poly-
imide selected from the N,N'-bis-maleimide of 4,4'-
diaminotriphenyl phosphate, the N,N'-bis-maleimide of
4,4'-diamino-triphenyl thiophosphate, the N,N',N'-tris-
. 30 maleimide of tris-(4-aminophenyl) phosphate, the
N,N',N"-tris-maleimide of tris-(4-aminophenyl)
thiophosphate; or a mixture of said polyimides;
and,
(b) a heat-activated curing agent for said
polyimide (a) comprising, in combination,
~2~3~
(i) an arylene polyamine compound of the
formula
S Q (NH2) , or
N~ ~ ~
wherein X is selected from hydrogen, lower alkyl, halogen,
or mixtures thereof, and Q is a divalent radical com-
prising at least two aryl radicals atached directly to
each other or through a member selected from an.alkylene
radical, straight chain or branched, of from 2 to 12
carbon atoms, -S-, -SO2-, -CO-, -O-, -CO2-(CH2) -CO2-
wherein p is from 2 to 12, or a mixture of any of the
foregoing members, and y' is 2, R each are divalent
hydrocarbon radicals obtained by removing the oxygen
atom of an aldehyde or ketone having 1 to 8 carbon
atoms, and m is a number of from 0.1 to 2; and
(ii) an alkenylphenol selected from o,o'-
diallyl-bisphenol A, 4,4'-dihydroxy--3,3'-diallyldiphenyl,
~5 bis-(4-hydroxy-3-allylphenyl) methane, 2,2-bis-(4-hydroxy-
3,5-diallylphenyl)propane, eugenol, o,o'-dimethallyl-
bisphenol A, 4,4'-dihydroxy-3,3'-dimethylallyldiphenyl,
bis-(4-hydroxy-3-methallylphenyl)methane, 2,2-bis-
(4-hydroxy-3,5-dimethallylphenyl)propane or 4-methallyl-
2-methoxyphenol; or an alkenylphenol ether selected from
2~2-bis(4-methoxy-3-allylphenyl) propane, 2,2-bis(4-
methoxy-3-methallyphenyl)propane, 4,4'-dimethoxy-3,3'
diallyldiphenyl, 4,4'-dimethoxy-3,3'-dimethallyldiphenyl,
bis(4-methoxy-3-allylphenyl)methane, bis(4-methoxy-3-
35 methallylphenyl)methane, 2,2-bis(4-methoxy-3,5-diallyl-
o ~ 27~ 3~
phenyl)propane, 2,2-bis-(4-methoxy-3,5-dimethallyl-
phenyl)propane, 4-allylveratrole or 4-methallylveratrole;
or
a mixture of said alkenylphenols, a mixture of
said alkenylphenol ethers or a mixture of said alkenyl-
phenols and said alkenylphenol ethers;
in amounts such that if N represents the
number of moles of polyimide employed, N represents the
number of moles of polyamine employed and N represents
the number of moles of alkenylphenol or ether thereoE
employed, the ratio
Nl Nl
or
152 3 2(m -~ 2)N + N
is from 0.3 to 10, y' or m being defined as above.
DETAILED DESCRIPTION OF THE INVENTION
Useful polyimides for component (a) contain,
per molecule, at least two radicals of the general
formula:
25/ CO \
D \ / N-
CO
in which D denotes a divalent radical containing a
carbon-carbon double bond.
The polyimides are known, and can be prepared,
for example, as described in U.S. 3,010,290, by reacting
the corresponding diamines with unsaturated dicarboxylic
acid anhydrides. It is contemplated to employ any of
the polyimides which are listed in the above-mentioned
3L27~
~rench Pat. No. 1,555,564, and in U.S. 4,100,140.
Maleimides of the above general formula in which D
denotes divalent radicals of the formulae:
R - C - CH = C -
ll or 2
CH- CH2-
in which R is hydrogen or methyl, are particularly
suitable.
The reaction with polyimides which contain,
per molecule, two or three radicals represented by D,
and thus, in particular, the reaction with bis-maleimides
and tris-maleimides, is a preferred embodiment of the
invention.
As has been mentioned, especially suitable
compositions are those wherein component (a) comprises a
mixture of heat curable polyimide resins of the formula
CO ~CO
D / N Z - N \ D
CO CO
wherein D is
CH C - CH - C - or CIH -
3 11 2
CH- CH2 CH -
or a mixture thereof, and Z is the residue of at least
one aromatic diamine and in the minor proportion of the
mixture, Z is the residue of an aliphatic diamine.
In such compositions preferably from 75 to 95
parts by weight of 100 parts of the mixture consists of
bis-imides derived from aromatic diamines. Illustrative
- ~.2~15~?~
o
of the preferred maleimides are those derived from at
least one diamine selected from ethylene diamine, hexa-
methylene diamine, phenylene diamine, trimethylhexa-
methylene diamine, methylene dianiline, toluene diamine,
4,4'-diphenylmethane diamine, 4,4'-diphenyl-ether diamine,
4,4'-diphenylsulfone diamine, 4,4'-dicyclohexanemethane
diamine, metaxylene diamine, 4,4'-diphenylcyclohexane
diamine, 3,3'-diphenylsulfone diamine or a mixture of
any of the foregoing. The best mixture of polyimides
will be those having a melting point from 70 to 125C.
Special mention is made of the eutectic-like mixture
known in the art and described in U.S. 4,454,283, which
is a bismaleimide mixt~re derived from diamines consisting
essentially of 50 to 80% methylene dianiline, 5 to 30~
toluene diamine and 5 to 25~ of trimethyl hexamethylene-
diamine, by weight.
Other illustrative bis-maleimides are compounds
of the formula:
C / \ / `C
II N-A-N
\C~ CO
in which R is hydrogen or lower alkyl (i.e., C -C6
alkyl), preferably, hydrogen or methyl, and A denotes a
divalent organic radical with 2 to 40 carbon atoms.
In the above formula, A is especially preferably
Of the formula:
~ (R
. .
- 10 -
wherein R represents one of the radicals -CH -,
C
CH3
SO -, -SO-, -S- and -O- and n is 0 or 1.
Illustrative examples of suitable polyimides
are: N,N'-ethylene-bis-maleimide, N,N'-hexamethylene-
bismaleimide, N,N'-m-phenylene-bis-maleimide, N,N'-p-
phenylene-bis-maleimide, N,N'-4,4'-diphenylmethane-bis-
maleimide, N,N'-4,4'-3,3'dichloro-diphenylmethane-bis-
maleimide, N,N'-4,4'(diphenyl ether)-bis-maleimide,
N,N'-4,4'-diphenylsulphone-bis-maleimide, N,N'-4,4'-
dicyclohexylmethanebis-maleimide, N,N'-alpha,alpha'-
4,4'-dimethylenecyclohexanebis-maleimide, N,N'-m-
xylylene-bis-maleimide, N,N'-p-xylylene-bis-maleimide,
N,N'-4,4'-diphenylcyclohexanebis-maleimide, N,N'-m-
phenylene-bis-citraconimide, N,N'-4,4'-diphenylmethane-
bis-citraconimide, N,N'-4,4',2,2-diphenylpropane-bis-
maleimide, ~,N'-alpha,alpha'-1,3-dipropylene-5,5-
dimethyl-hydantoin-bis-maleimide, N,N'4,4'-diphenyl-
methane-bis-itaconimide, N.N'-p-phenylenebis-itaconimide,
N,N'-4,4'-diphenylmethane-bis-dimethylmaleimide, N,N'-
4,4'-2,2-diphenylpropane-bis-dimethylmaleimide, ~,N'-
hexamethylene-bis-dimethylmaleimide, N,N'-4,4'-(diphenyl
èther)-bis-dimethylmaleimide and N,N'-4,4'-diphenyl-
sulphone-bis-dimethylmaleimide. Special mention is made
of N,N'-4,4'-diphenylmethane-bis-maleimide, also known
as 4,4'-bismaleimidodiphenylmethane.
In harmony with the teachings of U.S. 4,100,140,
bis-imides and tris-imides containing phosphorus can
also be ~sed:
- :~2~5~
- 11 -
(O -A')
O
~ (- A N \ / D)3_q
wherein A' and A" are optionally substituted aromatic
radicals or aromatic radicals which are interrupted by
an oxygen atom, an alkylene group or a sulfonyl group, D
is as defined above, Z is oxygen or sulfur, q is 1 or 0.
These are described in German Published Patent Applica-
tion No. 2,350,471.
Illustrative examples of these are: the N,N'-
bis-maleimide of 4,4'-diamino-triphenyl phosphate, the
N ,N ' -bis-maleimide of 4,4'-diamino-triphenyl
thiophosphate, the N,N',N'-tris-maleimide of tris-(4-
aminophenyl) phosphate and the N,N',N"-tris-maleimide of
tris-(4-aminophenyl) thiophosphate.
As mentioned, the invention contemplates the
use also of mixtures of two or more of all of the above-
mentioned polyimides. In addition, mixtures of polymides
with monoimides containing the radical D above defined
can also be employed according to the invention.
The polyamines used as component (b)(i) will
be oE the general formulae:
~-(NH2) or
~ r ~ ~ ~
- R~ -
35 wherein G is a y-valent organic radical having 2 to 40
~L 27~
12 . 61109-7449
carbon atoms and y is an inte~er from 2 to 4, and each R is a
divalent hydrocarbon radical obtained by removing the oxygen a~om
o~ an aldehyde ~rketone having 1 to 8 carbon atoms, and m
represents a number from 0.1 to 2.
The polyamines of the formulae are known compounds. If
the polyamine is a diprimary polyamine, G has the same meaning as
A above and y denotes 2.
A preferred family of amines are arylene polyamine
compounds of the formulae:
. Q ~N~l2)y or
NH2 NH2 NH2
~ R ~ R
wherein Q is a divalent radical comprising at least two aryl
radicals attached directly to each other or through a member
selected from an alkylene radical, straight chain or branched, of
from 2 to 12 carbon atoms, -S-, -S02-, -C0-, -0-, -C02-(CH2)p-C02-
wherein p ls from 2 to 12, or Q is a divalent radical comprising
an aliphatic or cycloaliphatic radlcal, straight chain or
~ranched, o~ from 2 to 12 carbon atoms, which may also contaln
~ O O
Il 11
-S-, -S02-, -C-, -O-, -C-0-, and the like, or a mixture of any of
~Q~
12a 61109-7449
the foregoing members, and y' is 2, R each are divalent
hydrocarbon radicals obtained by removing the oxygen atom of an
aldehyde or ketone having 1 to 8 carbon atoms, and m is a number
of from 0.1 to 2. Preferably R i5 CH2 and m has an average value
sufficient to provide an equivalent ~7eight of about 50 to 53.
Illustrat,ive of diamines are: ~,4'diaminodicyclo-
hexylmethane, 1,4-diaminocyclohexane, m-phenylene-
I
~Z~ 3~
o
diamine, p-phenylenediamine, 4,4'-diamino-diphenylmethane,
bis-(4-aminophenyl)-2,2-propane, 4,4'-diamino-diphenyl
ether, 4,4'-diaminodiphenylsulfone, 1,5-diaminoz?htha-
lene, m-xylylenediamine, p-xylylenediamine, ethylene-
diamine, hexamethylenediamine, bis-(gamma-aminopropyl)
-5,5-dimethyl-hydantoin and 4,4'-diaminotriphenyl
phosphate, and the like. m-Phenylenediamine, 4,4'-di-
aminodiphenylmethane, 4,4'diami.no-diphenyl ether,
hexamethylenediamine, 4,4'diamino-triphenyl phos?hate or
4,4'-diamino-triphenyl thiophosphate are preferred.
Polyamines different from the diprimary poly-
amines include those which have less than 40 car~on
atoms and contain 3 or 4 NH groups per molecule. The
~H groups can be substitutents on a benzene ri.ng which
is optionally substituted by methyl groups, or a naph-
thalene ring, on a pyridine ri.ng or on a triazine ring.
They can also be substitutents on several benzen- rings
which are linked to one another via a single valency
bond, an atom or an inert group which have already been
mentioned under the diprimary polyamines, or by one of
the following groups
O S
-N- , -CH~, -O-P-O- , -O-P-O- and -O-P-O-
O O O
l l l
Such polyamines include: 1,2,4-triaminoben-
zene, 1,3,5-triaminobenzene, 2,4,6-triaminotoluene,
2,4,6-triamino-1,3,5-trimethylbenzene, 1,3,7-tri-amino-
30 naphthalene, 2,4,4'-triaminophenyl, 3,4,6-triamino-
pyridine, 2,4,4'-triaminophenyl ether, 2,4,4'-triamino-
diphenylmethane, 2,4,4'-triaminodiphenyl-sulfone,
2,4,4'-triaminobenzophenone, 2,4,4'-triamino-3-methyl-
diphenylmethane, N,N,N-tri(4-aminophenyl)-amine,
tri-(4-aminophenyl)-methane, tri-(4-aminophenyl)
5 ~ ~ ;~
- 14-
o
phosphate, tri-t4-aminophenyl) phosphite, tri-(4-amino-
phenyl) thiophosphate, 3,5,4'-triaminobenzanilide,
melamine, 3,5,3,5'-tetraaminobenzophenone, 1,2,4,5--
tetraaminoben'zene, 2,3,6,7-tetraaminoaphthalene,
3,3'-diaminobenzidine, 3,3',4,4'-tetraaminophenyl ether,
3,3',4,~'-tetraaminodiphenylmethane, 3,3',4,4'-tetra-
aminodiphenylsulfone and 3,3-bis-(3,3'-diamino-phenyl)-
py~idine.
The polyamines of the second formula are known
compounds and can be obtained in accordance with the
processes described in French Patent Specifications
1,430,977 and 1,481,935 by reacting primary aromatic
amines with aldehydes or ketones. Examples of aldehydes
or ketones used are formaldehyde, acetaldehyde,
benzaldehyde, oenanthaldehyde, acetone, methyl ethyl
ketone, cyclohexanone and acetophenone.
Mixtures of 2 or more polyamines of the formulae
can also be reacted with the polyimides and/or allyl-
phenols and/or all'yl-phenolethers.
The allylphenols and methallylphenols, or the
ethers thereof, used as component (b)(ii) herein are
preferably employed as the alkenylphenols or alkenylphenol
ethers. Both mononuclear and polynuclear, preferably
binuclear, alkenylphenols and alkenylphenol ethers can
be employed. Preferably, at least one nucleus contains
both an alkenyl group and a phenolic, optionally
etherified, OH group.
Alkenylphenols can be made by rearrangement of
the alkenyl ethers of phenols (for example oE the allyl
ether of phenol) by the action of heat (Claisen rearrange-
ment). These alkenyl ethers are also obtained according
to known processes by reacting phenols and, for example,
allyl chloride in the presence of an alkali meta~ hydroxide
and solvents. By so doing, a condensation reaction
takes place with elimination of alkali metal chloride.
~7~
- 15-
Typical binuclear alkenylphenols are of the
formula:
CH -CH = CH2
HO ~ -(R ) 2 ~ ~ ~ OH
CH =C~ - CH2
in which R and n have the meanings set forth above.
The use of mixtures of polynuclear alkenyl-
phenols and/or alkenylphenol ethers with mononuclear
alkenylphenols and/or alkenylphenol ethers is also with-
in the invention. The alkenylphenol ethers preferably
employed are those substances which contain one or more
molecular radicals of the formula:
O - R
wherein R is an alkyl radical of 1 to 10 carbon atoms,
an aryl radical or an alkenyl radical, preferably allyl
or methallyl~ the O atom in the formula representing the
phenolic ether bridge.
A further feature of the invention comprises
using mixtures of those substances which contain only
one OH group and only one alkenyl group on the aromatic
nucleus with substances which contain several OH groups
and/or several alkenyl groups on the aromatic nucleus,
or of mixtures of the corresponding phenol ethers of
these substances.
Illustrative of alkenylphenols useful in the
invention are: o,o'-diallyl-bisphenol A, 4,4'-hydroxy-
3,3'-allyldiphenyl, bis-(4-hydroxy-3-allylphenyl)-methane,
2,2-bis-(4-hydroxy-3,5-diallyl-phenyl)-propane and
_ 16-
eugenol. The corresponding methallyl compounds can also
be used. In place of the said alkenylphenols it is also
possible to use the corresponding ethers of these phenols,
especially the methyl ëthers.
As has been mentioned above, in the present
compositions, if N represents the number of moles of
bisimide (a) employed, N represents the number of moles
of polyamine employed, and N represents the number of
moles of allylphenol and/or allylphenol ether employed,
and y or m represents the valence of the amine or amines,
then the ratios
Nl
_ - or
2 3 2(m + l)N2 + N3
are greater than 0.3. Preferably, the amounts of
reactants are chosen so that the ratio is between 1.3
and 10, especially preferably between 1.5 and lO. The
amounts of polyamine (b)(i) and allylphenol and/or
allylphenol ether (b)(ii) are generally so chosen that
y N
is between 0.05 and 20, preferably between 0.1 and lO.
As has been mentioned above, in the process of
the present invention, the maleimides in which D contains
a carbon-carbon double bond, are reacted with a combina-
tion of a polyamine and an alkenylphenol and/or alkenyl-
phenol ether, optionally in the presence of polymerisation
catalysts.
In most cases the reaction according to the
invention is carried out at temperatures of 20 to
?
-17 -
250C. and preferably of 100 to 250C.
Also according to the invention, the reaction
can be carried out in the presence of phenols, such as,
for example, carbolic acid, cresol and bisphenol A.
That is to say commercial alkenylphenols, and the
corresponding ethers, which still contain residues of
the phenols used as the starting materials, can also be
employed for the reaction according to the invention.
Polymerisation catalysts useful in the inven-
tion are ionic and free-radical catalysts. They may be
present in the reaction mixture in a concentration of
0.1 to 10% by weight, preferably of 0.1 to 5% by weight,
based on the total amount of the reactants.
As ionic catalysts, there can be used tertiary
or secondary amines or amines which contain several
amino groups of different types (for example mixed
tertiary/secondary amines) and quaternary ammonium
compounds. The amine catalysts can be monoamines or
polyamines. When secondary amines are used, monoamines
are preferred~ Illustrative are: diethylamine, tri-
butylamine, triethylamine, triamylamine, benzylmethyl-
amine, tetramethyldiaminodiphenylmethane, N,N-diisobutyl-
aminoacetonitrile, N,N-dibutylaminoacetonitrile, hetero-
cyclic bases, such as quinoline, N~methylpyrrolidine,
imidazole, 2-phenyl imidazole, benzimidazole and their
homologues, and also mercaptobenzothiazole. Also suitable
are benzyltrimethylammonium hydroxide and benzyltri-
methylammonium methoxide, and the like.
Also suitable as ionic catalysts are alkali
metal compounds, such as alkali metal alcoholates and
alkali metal hydroxides. Sodium methylate is preferred.
As free-radical polymerization catalysts can
be employed organic peroxides and hydroperoxides as well
as azoisobutyronitrile. In this case also, the preferred
35 concentration is 0.1 to 5.0% by weight.
5~Z
-18 -
Further polymerisation catalysts which can be
employed for the process according to the invention are
acetyl-acetonates, especially the acetyl-acetonates of
the transistion metals. Special mention is made of the
corresponding vanadium compound.
The reaction according to the invention is
preferably carried out in the melt, or partly in the
melt and partly in the solid phase. However, it can
also be carried out in solution. In most cases, however,
the addition of solvents can be dispensed with because
the starting mixtures as such are already of sufficiently
low viscosity even at medium temperatures (for example
at 120C.). When the process is carried out in the
melt, temperatures of 100 to 250C. are particularly
suitable.
The following substances can be listed as
examples of suitable solvents: chloroform, methylene
chloride, methyl cellosolve, dioxane, tetrahydrofuran,
dimethylformamide, tetramethylurea and N-methyl-
pyrrolidone.
The process according to the invention canalso be carried out in two stages, in the following
manner. After all of the starting materials have been
mixed, and optionally after subsequent grinding of the
mixture, the powder or the liquid is first heated for a
limited time to, preferably, 120-170C. A product
which can still be molded by the action of heat and, in
some cases, is soluble is formed. If necessary, this
prepolymer must be ground again to give a powder which
can be processed, before it is finally cured during
rinal processing. The pre-polymerisation can also be
carried out by heating a solution or suspension of the
starting materials.
As a rule, the preparation, according to the
invention, of the crosslinked polymers containing imide
~ ~7 ~
- 19 -
groups is carried out with simultaneous shaping to give
shaped articles~ sheet-like structures, laminates,
adhesive bonds or foams. The additives customary in the
technology of curable plastics, such as fillers,
plasticizers, pigments, dyestuffs, mold-release agents
and flame-retarding substances, can be added to the
curable compositionsl Examples of fillers which can be
used are glass fibers, mica, graphite fiber, quartz
fiber, polyaramid fiber (KEVLAR~), kaolin, colloidal
silica or metal powders and examples of mold-release
agents which can be used are silicone oil, various
waxes, zinc stearate or calcium stearate and the like.
Shaping of the product which can be manufactured
by the process according to the invention can be effected
in an extremely simple manner by a casting process using
a casting mold. Shaping can also be carried out by hot
molding using a press. Usually it suffices when the
product is heated only briefly to temperatures of 170
to 250~C. under a pressure of 1 to 200 kg/cm and the
molding, thus obtained, is fully cured outside the
press.
The process according to the invention and the
polyaddition products which can be produced by this pro-
cess can be used in manufacturing castings, surface
protection, electrical engineering, laminating processes,
adhesives, in the manufacture of foams and in the building
trades.
DESCRIPTION OF THE PREFERRED EI~BODI~ENTS
The following non-limiting examples illustrate
the compositions and methods of the present invention
and its advantages over compositions representative of
the state of the art. All parts and percentages are by
weight.
~ ~7 ~ !
_ 20 -
EXA~PLES 1-3
~ eighed amounts of the bismaleimide of 4,4'--
diaminodiphenylmethane, o,o'-diallyl bisphenol A (~.S.
4,100,140, Cols. 6-7) and the respective polyamines are
heated to 120 to 150C. and the melt is degassed and
poured into molds preheated to 150C. The mixtures are
heated in an oven, in a first stage to 177C~ for four
hours and in a second stage to 232C. for four hours.
After cooling slowly, castings are obtained and physical,
and flexural properties are determined by the following
procedures: The flexural test is described in ASTM
D-790, Method I. Dynamic mechanical analysis was
performed on a Dupont 981 Dynamic Mechanical Analyzer,
and T was defined as the temperature at which the loss
tangent, tan ~ , is a maximum. ASTM D4065 test method
covers this type oE T measurement. Conditionihg before
testing is described g~y the phrases "wet" and "dry".
"Wet" refers to conditioning for two weeks at 71C.;
"Dry" means testing a sample, as prepared, at 23C.
For comparison purposes, a two component
polyimide/allylphenol mixture according to the prior art
(U.S. 4,100,140) is prepared and tested. The formulations
used and the results obtained are set forth in Table 1:
~LZ7~5~
~ o ,~
o ~ u~ ~ o
1 o ~ ~ ~ ~
,_
~ ~1 --~ ~r I I ~ o~ o o ' ~ ~ ~ ~ er c~
10 E~
~ .
O u~
~1 u~ .
z
æ ~ o ~
O o ~o ~r ~ . . . ~ 1-- ~ ~ ~1 ~ ~
H ~ O o o ~1 ~1 ~ U~ ~r O ~
~0
~ V ~ ~ ~ V ~ ~ ~
~ s
Z ~~ ~ ~ ~ ~ ~ ~ ~,~ C~ ~1 ~ C) ~
~ --~ 3 ~ ~ 3 ":1 ~ 3 ~ ~ 3 ~ ":1 3 '1:5
~: :~
a
~:V V ra~ ~ -
~s e ~ e ~
3 ~ ~ ~
a ~ c ,1; ~ c O
u~ ~ ~ ~ c ~
o ~ x a) s ~ ~ o
~ ~ ~ O S ~ E~
~ ~ ~ 0 ~ E s
~ c ~ ~ o c ~ ~ ~ ~ o
C~O ~ ~ C .r~ O ~ m ~ c
.. ~ ~ ~ c _1 1 _~
..~ u~ ~ o
~3 ._~ .~ 1 ~ 1 ~ ~ L~ ~ ~
u~ ~ ~ I ra. c ~ ~ v ~ o
w ~ ~ ! ! , l ,, a) ~ n 3 o c
~ ~ e ~ o ~ o ~ ~,
3 5 ~: x ~ ~ o ~ ~" b ~u 3 E~
-
- 22 - 61109-7449
The foregoing data demonstrate that the compositions
accordin~ to this invention are unexpectedly superior in heat resis-
tance, (higher Tg's), hot/wet properties, and/or resistance to
thermal decomposition (properties retained after thermal aging).
The following Examples 4-6 illustrate the inventionO
They represent work done by applicant~' co-worker, Bruce Allen
Stern, and they form the subject matter of United States Patent
4,608,426 and of Canadian Application 500,393.
EXAMPLES 4 AND 5
lo One hundred parts of a mixture of the bis-maleimides of
methylene dianiline (64 percent), trimethylhexamethylene diamine
(15 percent) and toluene diamine (21 percent) (KERIMID ~ 353,
Rhone-Poulenc) were mixed with 10 parts by weight of 3,3'-aiamino-
diphenyl sulfone, 25 parts of o,o'-diallyl-bis-phenol A (CIBA-Geigy)
and 0.25 parts of 2-ethyl-5-methylimidazole. Five parts of a fine-
ly divided silica (CABOSIL ~ M 5) was added as a thixotrope. The
composition gelled at a temperature of 350F. in 12 minutes. The
bis-maleimide without 2-ethyl-4-methylimidazole required more than
20 minutes at a temperature of 350F. to gel.
The composition is used to impregnate graphite and carbon
fibrous reinforcements in the form of tapes. The resin contents
range from to 28 parts to 42 parts per 100 parts of resin plus
fiber. The tapes are assembled into layers and consolidated under
heat (350-400F.) and moderate pressure (40-100 psi) into
lamina~ed panels. Good panels are obtained, with low shrinkage,
- 22a - 61109-7449
~:7~
well controlled, low flow, no blistering, having good thermal
stability and excellent impact strength. The properties obtained
will be tabulated hereafter for comparison with state of the art
- systems~ Example 4 comprises inter-
5~3~
-23 ~
mediate modulus carbon fibers (Hercules IM-6); Example 5
comprises high strength fibers (Celanese, CELION~ 6000).
EXAMPLE 6
The resin composition of Examples 4 and 5 is
used to impregnate glass and quartz fibrous reinforcements
in the form of fabric. The resin contents range from 25
to 40 parts per 100 parts of resin plus fiber. The
impregnated fabric material is consolidated under heat
and pressure into laminated shapes which are suitable
for radomes. Good panels are obtained with low flow,
low shrinkage, no blistering, good thermal stability and
excellent impact strength.
PROCEDURE A
For comparison purposes, a state-of-the-art
bis-maleimide system (U.S. 4,454,283) was formulated,
and laminates comprising unidirectional graphite fiber
tapes were impregnated with it and tested. 85 parts of
the mixture of bis-maleimides used in Example 4 herein,
27 parts of 55 percent divinyl benzene, 5 parts of the
trifunctional curing agent, triallyl isocyanurate and 1
part of the oxidation inhibitor, hydroquinone. During
preparation and use as an impregnant for the graphite
tapes, toxic odors and poor handleability were encoun-
tered. The resin contents ranged from 25 to 40 percent.
The tapes were consolidated under heat and pressure into
laminated panels. Good appearing panels were obtained
but the impact performance was poor, and edge delamina-
tion, especially, was found to be a problem. The proper-
ties obtained will be tabulated hereafter for comparison
with the compositions of this invention and that of
another state-of-the-art system~
3~
- 24 -
PROCEDURE B
For comparison purposes, a second and different
bis-maleimide system (U.S. 4,100,140) was formulated, and
l'aminates comprising'unidirectional graphite fiber tapes
were impregnated with it and tested. One hundred parts
of N,N'-4,4'-diphenylmethane-bis-maleimide (CIBA-Geigy
XU-292A) and 75 parts of o,o'-diallyl~bisphenol-A (CIBA-
Geigy XU-292B) are melted at 70-100C. and 5 parts of a
finely divided fumed colloidal silica (CABOSIL~ M 5) are
added as a thixotrope. The melt is used to impregnate
graphite or carbon fibrous reinforcements in the form of
tapes. The resin contents range from 25 to 40 parts per
100 parts of resin plus fiber. The tapes are assembled
into layers and consolidated under heat and pressure
into laminated panels. Good panels were obtained with
no blistering. The toughness as measured by impact
testing was good, but properties measured on the hot
panels were not as good and when measured on hot panels
after exposure to moisture, they were much worse.
Flexural modulus, as a specific example, when measured
on a dry panel at 450F~ was poor, and could not even
be measure~ after the panel had been exposed to moisture.
The data obtained after measuring important
physical properties are summarized in Table 2:
~7~)5~
-25 -
TABLE 2: PROPERTIES OF COMPOSITES COMPRISING GRAPHITE
BIS-MALEIMIDE RESINS
EXAMPLE 4 A B 5
Composition-(parts by weight?
Bis-maleimide/m-DDS/
o,o'-diallyl BPA 28-42 -- -- 28-42
Bis-maleimide/DVB -- 25-40 -- --
Bis-maleimide/o,o'~
diallyl BPA -- -- 25-40 --
Reinforcing graphite
fibers Balance* Balance* Balance** Balance**
Pro~erties
Impact Strength,
peel apart mode,
G , in.lbs./in 0.98 0.79 -- --
Impact Strength,
shear mode, 2
G , in.lbs./in 2.04 1.13 -- --
Incipient Impact Energy,
IIE, ft.lbs./mil. 4.49 1.80 -- ~-
Impact damage area,
10 ft.-lbs. (in ) 1.02 3.73 -- --
Edge Delamination Resistance
Stress at first crack,
ksi 26 14-16 41 40.9
Stress at failure,
ksi 76 -- 98 68.6
Flexural modulus
Dry
--6
30 Room temp.,psi x 10 18.6 -- 19.6 17.9
450F., psi x 10 18.6 -- 10.3 16~7
Wet -6 too poor
450F., psi x 10 _ 13.5 ~ to measure 10.6 _
* Intermediate Modulus, IM6
** High Strength, CELION
-26 -
o
From the foregoing results it is evident that
the resin compositions according to this invention
(Examples 4 and 5) provides good laminated panels with
excellent toughness as represented by impact testing and
by resistance to edge delamination, making it substan-
tially superior to the first state-of-the-art system
tA), and demonstrating thermal and moisture resistance,
as represented by flexural modulus test results,
substantially superior to the second state-of-the-art
system (B).
EXAMPLES 7 AND 8
~ r
The general procedure of Examples 1 and 2 was
repeated, making modifications in the formulations and
neat resin castings are made and tested. The formulations
used and the results obtained are set forth in Table 3:
~;~7~592
- 27 -
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cn
H
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u~ a~ o r~
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c~ I / ~1 ~ ~ I o o o o ~ ~ ~ u~ ~r In CO ~n u~
z
O O ~ ~ ~
1 c H ~1 ~ ~ Ln O Lt~ t--
L ~ ~ ~ O O ~O
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O ~ ~ V V ~ ~ V V
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Z v
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-28 -
EXAMPLE 9
o,o'-Diallylbisphenol A, 1963 g. was heated to
200F., then 3505 g. of the bismaleimide of methylene
dianiline was added. After the bismaleimide was thorough-
ly mixed, meta-diamine diphenylsulfone, 427 g., and
fumed colloidal silica (CABOSIL), 105 9. were added and
mixing was continued for 10 minutes. This mixture was
- coated onto unidirectional graphite (CELION~ 6000).
This unidirectional tape was cut and laid up and cured 4
hours at 350F. and 4 hours at 440F. to give a laminate
with the properties set foth in Table 4 (supra).
' EXAMPLE 10
To 1913 g. of o,o'-diallylbisphenol A which
has been heated to 200F. was added 741 g. of KERIMID~
353 (see Example 4) and 2966 g. of the bismaleimide of
methylene dianilini after 10 min., 111 g. of fumed
colloidal silica, 260 g. of meta-diaminodiphenyl sulfone,
and 9.3 g. of 2-ethyl-4-methylimidazole were added.
This mixture was coated onto unidirectional graphite
fibers (to make ~graphite tape" prepreg). The prepreg
was laid up and cured for 4 hours at 350F. and 4 hours
at 440F. to give a high'quality laminate with proper-
ties set forth in Table 4:
~Z7~5~3;~:
29 -
TABLE 4: PROPERTIES OF COMPOSITES COMPRISING GRAPHITE
AND BIS-MALEIMIDE RESINS
EXAMPLE 9 10
S ~_
Bis-maleimide/m-DDS/o,o'-diallyl BPA 28-42 --
Bis-maleimide mixture/o,o'-diallyl
BPA/m-DDS -- 28-42
Reinforcing graphite fibers, CELION~ Balance ~alance
Edge Delamination Resistance
Stress at first crack, ksi 42.2 27.1
Stress at failure, ksi 101.8 79.0
Flexural modulus
15 ~Y -6
Room temp., psi x 10 20.1 14.4
Wet 6
350F., psi x 10 18.2 13.0
-` ~27Ç~
- 30 - 61109-74~9
From the foregoing results it i5 evident that the resin
compositions according to this invention (Examples 9 and 10) pro-
vide good laminated panels with excellent toughness as represented
by resistance to edge delamination and demonstrating thermal and
moisture resistance, as represented by flexural modulus test
results.
Many variations in the present invention will suggest
themselves to those skilled in this art in light of the above
detailed description. For example, instead of a bis-maleimide
derived from maleic acid, one derived from citraconic or tetra-
hydrophthalic acid can be used. Instead of 3,3'-diaminodiphenyl
sulfone, 4,4'-di(3,3'-aminophenoxydiphenyl)sulfone can be used.
Instead of o,o'-diallyl bisphenol A, 4,4'-hydroxy-3,3'-allyldi-
phenyl can be used. Instead of 2-ethyl-4-methylimidazole, 2-
phenyl imidazole can be used. Instead of fibrous graphite or car-
bon, glass or quartz reinforcements, ceramic fibers, such as 3M
Company's NEXTEL ~ fibers, and DuPont Company's KEVLAR ~ aramid
fibers can be used. All such obvious modifications are within the
full intended scope of the appended claims.
