Note: Descriptions are shown in the official language in which they were submitted.
47Z8;Z
CROSSLINKABLE, CRYSTALLIZAElLE POLYARYLFTHERS
AND COMPOSITES TE~E~EFPOM
BACKGROUND OF THE INVENTION
This invention i6 directed to tough,
solvent resi~tant materials derived from
polyarylethers and fiber-reinforced composites made
from these materials.
Compo~ites comprised of continuous ~ibrou~
reinforcement such as graphite, aromatic polyamide
fiber, and glass in a polymeric matrix are u6eful
structural materials since they possess high
specific strengths and moduli compared to metals.
Such composites may be used to make load bearin~
~tructures in, for example, automobiles and aircraft.
In mo~t graphite-reinforced composites,
epoxy resin ~ystems are used as the matrix. Since
these re~i~s are often brittle, composites made with
them are subject to delamination when impacted.
To improve the impact resistance of fibe~
reinforced composites, a ductile thermoplastic such
as the polyarylether derived from
2,2-bis(4-hydroxyphenyl)propane (i.e., bi~phenol A)
and dichlorodiphenyl ~ulfone has been used a~ a
matrix resin. This re~in affords compo~ites with
good toughnes~, but is attac~ed by many common
organic solYent6 such as chlorinated hydrocarbon6,
ketones, and N,N-dimethyl acetamide. T~e lack of
solven~ re~istance limits the range of application~
where composites based on thi6 re~in may be used.
Kecently, attempts have been made to
i~pro~e the solvent re~i~tance of the polyarylet~er
D-13783
~2~72~
-- 2 --
derived from bisphenol A and dichlorodiphenyl
~ulfone. The polymer ha~ been modified by attaching
terminal group6 which take part in chain exten6ion
and crosslinking reactions when heated. Suitable
terminal group6 include maleimide, nadimide, and
ethynyl. Maleimide-terminated polyaryletherfi are
de6cribed in U.S. Patent 3,339,287,
nadimide-terminated polyarylethers are de6cribed by
C. H. Sheppard et al., 36th Annual Conference,
Reinforced Plastics/Compo6ite6 Ins~itute, Feb.
16-20, 1981, Se~6ion 17-B, page~ 1 to 5, and
ethynyl-terminated polyarylether6 are described by
P. ~. Hergenrother in J. Polymer. Sci., Polymer.
Chem. Ed., 20, 1982 pages 3131 to 31~6. All of
these polya~ylether~ are made with bisphenol A a~
the aromatic diphenol. Howe~er none of these resin
~ystem6 ha~ a high degree of solvent resi~tance.
THE INVENTION
Thi6 invention i~ directed to a) a
cry6tallizable, crosslinkable resin compri~ing
(i) a polyarylether of for~ula I
1 X ~ S~2 ~ R - ~ ~ X
wherein R i6 ~ cr
D-13783
:~Z~7213Z
- 3 -
n i8 4 to 100 and X i~ selected from
-0~ J ~ -~
o
o~N - c~ ~ - 0 ~ C-CH,
C=CH
-0-R-02C ~ , and -OCH2-C-CH
(ii) a cryxtallization promoting~pla~ticize~,- and
(b) fiber reinforced compo6ites made using (i) plu6
(ii) a6 the matcix resin.
The compo6itions of this invention exhibit
i~proved 601vent re6i6tance and environmental stre6s
crack re6i~ance as compared to compo~ition6
containing I derived fcom bi6phenol A.
The fiber-reinforced co-posite~ of thi~
invention compri~e fibrou~ reinforcement selected
f LOm one or mo~e of carbon or graphite fiber,
aromatic polyamide fiber, gla~6 fiber, or boron
fiber.
The polyarylether~ of formula _ contain a
backbone derived from 4,4'-dihalodiphenyl6ulfone and
an aromatic diphenol which is pri~arily:hydroquinone
or 4,4'-biphenol. The preferred
D-13783
~2472132
dihalodiphenylsulfone is g,~'dichlorodiphenylsul~one
~nd the preferred diphenol is hydroquinone. Up to
25 percent of the diphenol, on a molar basis, may be
replaced with bisphenol A, methylhydroquinone,
chloro hydroquinone, bis(4-hydroxyphenyl)methane,
bist4-hydroxyphenyl)- sulfide,
bi6(4-hydroxyphenyl)sulfone, resorcinol, or the
oligomeric hydroxyl-terminated polyarylethers as are
described in U.S. Patent 4,306,094. Up to 40 mole
percent of the dihalodiphenyl sulfone may be
replaced with other monomers including
4,4-dihalobenzophenones, 6uch as 4,~-difluorobenzo-
phenone or 4,4'-dichlorobenzophenone, or
2,6-dihalobenzonitriles, ~uch as 2,6-dichloro-
benzonitrile.
The terminal groups on I are ~elected from
~ ,C-CH
-OR02C~
~ 3 ~N
o o
~ H &~ C-CH
OCH2 -C-CH
Each undergoes chain extension and crosslinking
reactions upon application of heat. The method of
preparation of I depends on X.
D-13783
7~
~ c=c~
If -X is -OR02C ~
it may be prepared by a two ~tep proces~ comprising
i) preparation of a
hydroxyl-teEminatec1 polyaryle~her by ~e
condensation of a molar excess of an aromatic
diphenol with dichlorodiphenylsulPone at a
tempe~aturq of ~ro~ about 100C to about 220C in
the presence of base in a dipolar aprotic ~olvent.
Suitable process conditions are described in U.S.
Patents 4,108,837 and 4.200,728 and in British
Patent 1,4q2,366, and
ii) esterification of the terminal
hydroxyl group6 with an ethynyl-sub6tituted benzoyl
chlo~ide in ehe presence of an acid acceptor.
Either m-ethynyl benzoyl chloride or ~-ethynyl
benzoyl chloride may be used. Triethylamine is a
~uitable acid acceptor. Suitable solvents include
N-methylpycrolidinone, tetrahydrofuran, methylene
chloride or mixtures thereof.
The general procedure for carrying out the
synthe~is of polyarylether~ where X -
f==~ "~C-CH
-OR02C ~)
iB given in J. Polymer Sci., Polymer. Chem. Ed., 20,
lsB2, ~ages 3131 to 3146.
If X is
o
Il
--0~ / ~ '
D-13783
7Z8~
- 6 --
o
~
the polyarylether of formula I may be prepared by a
process comprising
i) preparation of an
amine-terminated polyarylether by condensing an
aminophenol, dihalodiphenylsulfone, and an aromatic
diphenol at elevated temperature in the presence of
base in a dipolar, aprotic solvent,
(ii) addition of maleic anhydride or
nadic anhydride, i.e., 5-norbornene-2,3-dicarboxylic
anhydride, to the terminal amine groups to form a
diamic acid followed by
(iii) imidization of the amic acid
groups by heat or by addition of a dehydrating agent
~uch as acetic anhydride.
Thi~ process is Pro~ess A. The conditions
for ~teps (i) through (iii) are given in U.S. Patent
3,839,287. Altsrnatively, step (i) may be carried
out u~ing the proce~ conditions of U.S. Patent
3,895,064 or Briti~h Patent 1,492,366.
The steps in Proce~s A are outlined in
Scheme I using p-aminophenol, hydroquinone, and
nadic anhydride.
D-13733
7;~8;~
~= ~ Q
C C ,~; ~o~
e ~ ' ~
V ~ _
C: ~
Z
~0
Z~
~Z~7~
Q
o Q=o
~,
~ C ~
o
'~ ~
o o
~ ~ .
o ~o o=~o
. ~
728~
g
The molecular weight o~ the amine-teL~inated
polyarylether inteemediate i6 controlled by the
molar ~atio of the aminophenol to a~omatic
diphenol. The amount of dihalodiphenyl ~ulfone u~ed
i~ ~uch that there are from 0.95 to 1.05 mole~ of
activated halide per mole of hydroxyl group. Either
m-aminophenol or p-aminophenol may be u~ed.
If X i8
o
--O ~C
~ ~ 3
o ~C
Il
o
an alternate procedure (i.e., Proce~ B) for the
preparation of I may be u~ed. This proce6s
comprise6
i) formation of a
hydroxyl-containing imide from an aminophenol and
either maleic anhydride or nadic anhydride, and
ii) condensation of
dihalodiphenyl~ulfone, aromatic diphenol, and the
product from (i) at a temperature of from about 100
D-137B3
72~3~
-- 10 --
to about 180C in a dipolar aprotic ~olvent in the
pre~errce of base. The condition6 for this 8tep a~e
~imilar to those for the preparation o~ the
amine-terminated polyarylether in step i) of Proce6s
A.
Process B i6 illu~t~ated in Scheme II using
p-aminophenol, hydroquinone, and nadic anhydride.
The synthe6is of the hydroxyl-containing imide is
de6cribed in the publication by C. H. Sheppard et
al. desc~ibed. 6U2~
D-13783
~4~72t~
Q
o ,
e ~ [~
O= --O
C
E~ Hl
Q~ .
+ Q~
:1~47~
- 12 -
If -X i~
~ H l C-CH
the eolya~ylether of formula I may be ~ynthesized by
a proces6 comprising
(i) preparation of an amine~terminated
polyarylethec by condensing an amino phenol,
dihalodiphenylsulfone, and an aromatic diphenol in
the presence of base in a dipolar aprotic solvent at
a temperature of 100 to 210C, followed by
(ii) amidation of the terminal amine groups with
m- or ~-ethynyl benzoyl chloride in the presence of
an a~id acceptor at -20C to 50C. In some case6,
the reaction solvent may ~erve as the acid accepto~.
A preferred solvent for the preparation of
I where X i8
- o C-CH
~N - C~ i6 N-methylpyrroli-
H O
dinone, since it can be used in both steps i and ii-
lf X i6
~ C-CH, the
polyarylether of formula I may be prepared ~y
condensing the aromatic diphenol, dihalodiphenyl-
sulfone, and thP ethynyl pheno~ ~0
D-13783
- 13 ~ 72~
in a dipolar aprotic solvent at 70 to 200C in the
presance o~ ba~e. The synthe6is of m-ethynyl phenol
i~ described in U.S. Patent 4,108,926.
If X is
-CH2 C_CH-
the polyarylether of formula I may be prepared by
condensing the ~romatic diphenol,
dihalodiphenyl-~ulfone, and propargyl chloride in a
dipolar aprotic solvent in the presence of base.
Preferably, propargyl chloride is added ~ubsequent
to the formation of a hydroxyl-ter~inated
polyarylether from the dihalodiphenyl-sulfone and an
excess of aromatic diphenol.
In the composition, the orystallization
promoting plasticizer induce~ crystalliniey in the
polyarylether backbone of I upon application of heat.
The crystallization promoting plasticizers
are of two types. The first type does not react
with the polyarylether o~ formula I and i8
characterized by solubility wi~h the polyarylether,
a glass transition temperature of <30C, low
volatility (e.~. boiling point >300C), and
excellent thermal stability. The second type reacts
with the polyarylether of ~ormula I and may
optionally react ~ith it~elf and is oharaoterized by
a gla~s transition te~perature of ~70C and a
boiling point of >200C. Examples of the first
type are triarylphospha~e esters, terphenyls,
hydrogenated terphenyls, quaterphenyl~, hydrogenated
quaterphenyls, polytphenylene oxide
D-13783
~Z472~
G~
~ wherein n = 2 to 15,
4,4'dichlorodiphenylsulfone, 4,4'dichlorobenzo-
phenone, other substituted diphenyl sulfone or
benzophenones as well as substituted diphenylethers,
and mixtures thereof. Suitable plasticizers of the
second type include 4,4'-bis(3-ethynylphenoxy)
diphenyl sulfone, triallyl cyanurate, and diallyl
phthalate, triallyl trimellitate, the biscyanate of
bisphenol A, diamino diphenyl methane, 1-amino-3
ethynylbenzene, l~hydroxy 3-ethynylbenzene,
2,2'-bis~3-ethynyl-phenoxy-4-phenyl)propane, divinyl
adipate, divinylether of l,4-butanediol,
N-phenyl-maleimide~ bismaleimide of 4,4'-
diaminodiphenyl methane, N-vinyl-2-pyrrolidinone,
and mixtures thereof.
The crystallizable, crosslinkable
compositions of this invention (i.e., i and ii plus
t~e plasticizer) may be prepared by mixing the
components at a temperature of from about 100C to
about 350C in conventional polymer compounding
equipment such as a Banbury mixer or extruder.
Preferably the mixing time is short and the mixing
temperature low to minimize premature crosslinking.
An inert gas atmosphere is preferred when
compounding the ethynyl-terminated polyarylethers.
An alternative method for combining I and
the crystallization promoter is to dissolve or
disperse them in a liquid such as N-methyl
pyrrolidinone, N,N-dimethylacetamide, methylene
chloride, tetrahydrofuran, sulfolane, or mixtures
thereof. The liquid may be removed by evaporation
or by pouring the mixture into a liquid which
dissolves the carrier but neither I nor the
Trademark
D-13783
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124'7~
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crystallization promoter. For many mixtu~e~ in
~-methylpycr~lidinone or N,N-dimethylacetamide,
precipitation in water ifi sati~factory. A solid
mixture of I and the promoter can then be recovered
by filtLation, dcied and cured.
Compo~itions with improved solvent
re~istance are prepared by heating the mixture of I
and the crystallization promoter at a tempe~atu~e of
from about 100C to about 350C. The time and
~empecature depend on the level of ~olvent
resistance desiced. The preferred temperature is
above the gla6s transition temperature of the
mixture and below the melting point of pure I.
The fiber reinforced composites of this
invention are fabricated using technique~ known in
the art. For example thin film~ of the mixture of I
and the cry6tallization promoter ~ay be prepared and
intecleaved between plie6 of fibLou6 reinforcement
in the form of woven cloth or unidirectional tape.
A laminate may be prepaced by heating thi6 ma 8 in a
heated pre66. Alternatively, composite6 may be
prepared from p~ep~eg-an intimate ~ixture of I and
the cry~tallization ~romoter with the fiber6.
Prepreg may be made by drawing the fibers through a
heated bath containing 1, the cry~tallization
promoter, and a 601vent, followed by evaporation of
the solvent by the application of heat.
Other pro~es~es include applying a ~lur~y
containing I and the ~ry6tallization pcomoter to a
reinforcement prior to heating and compaction, a~
de~cribed in, ~or example, U.S. Patent 4,292,105.
Preimpregnated reinforcement a6 well as la~inated
D-13783
- 16 - ~Z47'~
~heet may be prepared u~ing heated calendar rolls as
de6cribed in, ~or example, U.S. Patent 3,~49,174.
The number average molecular weight of the
polyarylether of ~ormula I, i8 from abou~ 2,000 to
abou~ 30,000, preferably from about 2,500 to about
25,000, and mo6t preferably from about 5,000 to
about 20,000. The polyarylethers of formula I are
solid~ which melt or often belo~ 380C.
The compositions of ~his invention (I plu~
the crystallization promoter) may be u~ed wi~h cr
without reinforcement. In the ab~ence of
reinforcement they contain up to 50 percent by
weigh~ of the cry~tallization promoter. In
reinforced compositions, the amount o~ I i6 from
about 10 to about 90 percent by weight, the amount
of crystallization promoter i8 from 0.5 ~o about 25
percent by weight and the amount of reinforcement i~
from about 5 to about 85 percent by weight. They
may be extruded, compre~ion molded, and injection
molded. They may al~o be u~ed ~ films, coatings~
adhesive~, and ~ealant6. They may be combined with
particula~e fillers 6uch a6 carbon black, talc,
mica, and caloium carbonate. C~opped fibers and
continuou~ filament~ may be u6ed.
Suitable reinforcement~ have a mel~ing
point or decomposition poin~ above 200C. and
include one or more of alumina, titania, ~ilicon
carbide, 6ilicon boride, polybenzothiazole a~ well
a the reinforcements listed above.
Cro~slinking may be carried ou~ ~ith the
aid o~ free radical initiator6 or radiation.
Suitable initiator~ include dicumyl peroxide,
di-t-butylperoxide, 1,1,2,2-tetraarylethanes,
1,1,1,2,2-pen~aarylethane~ and the like.
D-13783
7213~
- 17 -
EXAMPI,~S
The following Examples serve to give
specific illustrations of the practice of this
invention but they are not intended in any way to
limit the scope of this invention.
Example 1
A 1 liter 4-neck flask e~uipped with a
mechanical stirrer, thermometer, addition funnel,
nitrogen purge line, a Dean-Stark trap and condenser
was charged with 129.22 g. of dichlorodiphenylsul-
fone, 48.45 g. of hydro~uinone, 2.21 g. of
p-aminophenol, 80085 g. of potassium carbonate, 137
ml. of chlorobenzene and 368 ml. of sulfolane. This
mixture was purged with nitrogen for one-half hour
at room temperature (about 25C) while stirring. It
was then heated to 210C as chlorobenzene and the
chlorobenæene-water azeotrope were distilled from
the mixture. The temperature was maintained at
21CC for two hours by the dropwise addition of
180 ml of chlorobenzene. The reaction mixture,
which now contained an amine-terminated
polyarylether, was cooled to 170C and 3.94 g. of
nadic anhydride was added. After two hours at a
temperature of 160 to 170C, the mixture was poured
into a foil-lined pan and allowed to cool. Once the
reaction product had solidified, it was broken and
washed in a blender with 2 liters of deionized
water. The insoluble material was recovered by
filtration and was washed with three portions (500
ml.) of deionized water. After it was slurried in 2
liters of methanol, it was dried under a vacuum.
The isolated yield of product was 145 g. Infrared
Trademark
D-13783
~24~8~
- 18 -
analysi~ indicated that the product was a
nadimide-terminated polyarylether which bad a
reduced viscosity of 0.50 as measured in
N-methylpyrrolidinone a~ 25~C at a concentration of
0.2 g/dl.
Control A
The followin~ materials were added to the
{eaction flask:
43.9 9. of phenoxynadimide, 85.3 g. of
bisphenol A, 110.07 9. of dichlorodiphenylsulfone,
55.6 g. of potassium carbonate, and 760 ml. of a
mixture of dimethylace~amide and toluene. The
content~ were heated at 140C for 72 hours.
The reactio~ product had a reduced
viscosity of 0.50 as mea~ured in
N-methylpyrrolidinone at 25C at a concentration of
0.2 g/100 ml.
Example 2
Preparation of molded Plaques and solven_
te6tinq.
~ hen cured at 250C for several hours
molded pieces of the material of Example 1 were
totally unaf~ected by immersion in eit~er methylene
chloride or dimethylace~amide, while piecss molded
from the material of Control A swelled tremendou61y
in these 601vents, when cured under the ~ame
conditions.
Thi6 result shows the improved sol~ent
resistance of the composition of this invention with
hydroquinone a6 the diphenol in the polyarylether
backbone a~ compared to Control A which i~ based on
D-13783
:~LZ~7Z8~
bisphenol A. However, further improvement~
'pa~ticularly in regard to environmental ~res~ crack
resistance is desirable and a means for achieving
this i~ 6hown in Examples 3 and 4.
Solvent Resistance of Nadimide - Terminated Polymerfi
SampleA _re Condition6 Effect of SolventB
Control A 2 hrs. @ 250 swell6 greatly
Products " " " un~ffected
of " " " unaffectedC
Ex 1
A lx2 cm strips cut from 4"x4"xlO mil plaque molded at
275C @ 4000 psi.
Solvent was methylene chloride unless indicated
otherwise.
C N,N-di~ethylace~amide
Control B
Environmental Stre~ Crack Resi~tance of a molded
pla~ule made from the Product of ExamPle 1
Tbe material from example 1 ~as heated to
310C and compression molded into a 4"x4"x20 mil
plaque and allowed to further react for ~wo hour~ at
250C. This was followed by an annealing step of 2
hours at 200C. The resultant material was tested
for environmental ~trsss crack re~istance to acetone
and methyl ethyl ketone. The time to rupture
re~ults were 2 second~ in methyl ethyl ~etone and 3
seconds in acetone when subjected to a 6tress of
1000 p~ i .
Modulus - temperature data were obtained on
the material described in this example which had
been molded and heated for two hours at 250C but
not annealed at 200C. The modulu~-tempera~ure data
revealed an amorphous product with no cryfitalline
D-13783
~Z~7~
- 20 -
modulus plateau. The measured 1'~ secant modulus
values at 200C, 225C, 250C, respectively were 200
psi, ~6 psi, 8 psi. Calorimetric data were obtalned
by heating to 400C at 10C/min. under N2 on the
DuPont/990 Thermal Analyzer. No evidence for
crystallinity was obtained.
Example 3
Environmental StressCrack Resistance of Mixtures of
the Product of Example 1 and a Crystallization
Promoter
The material from example 1 (8.5 grams) was
slurried with an acetone solution containing 1.5
grams of triphenylphosphate. After devolatilization
of acetone, the material was heated to 310C and
compression molded into a 4"x4"x20 mil plaque and
then allowed to further react for two hours at
250C. This was followed by an annealing step of 2
hours at 200C. The resultant material was tested
for ~nvironmental stress cracks resistance to
acetone and methyl ethyl ketone. The time to
rupture results were 0.08 hours in methyl ethyl
ketoneand 0.12 hours in acetone when subjected to a
stress of 1000 psi.
Modulus - temperature data were obtained on
the material described in this example which had
been molded and heated for two hours at 250C but
not annealed at 200C. Modulus-temperature data
revealed a semi-crystalline product with distinct
crystalline modulus plateau. The measured 1~ secant
modulus values at 200C, 225 C and 250C
respectively were 8,650 psi; 7,870 psi; and 4,970
psi. The crystalline melting point determined from
_
Trademark
D-13783
~Z4~7Z~3~
- 21 -
the modulus-tempe~atuce data was 280C.
Calorimet~ic data were obtained by heating to 400C
at 10C/min under N2 on the DuPont 990 Thermal
Analy~er~ Cry6tallinity wa~ pcesent. The
cry6talline melting point wa~ 272C and ~he heat of
fu~ion wa~ 6 . 5 cal . /gr .
Example 4
The material fcom example 1 (8.0 gram~) was
slucried with an acetone solution containin~ 2.0
gcams of triphenyl pho6phate. After
devolatilization of acetone, the material wa6 heated
to 310C and compre6sion molded into a 4"x4"x20 mil
plaque and allowed to furtber react for two hour~ at
250C. Thi6 wa~ followed by an annealing 6tep of 2
hours at 200C. The resultant material was te6ted
for environmental stres~ crack re~istance to acetone
and methyl ethyl ketone. The time to rupture
re~ult6 were 2.13 hour~ in methyl ethyl ketone and
1.20 hour6 in acetone when 6ubjected to a stress of
1000 p6i.
~ odulur-tempe~ature data were obtained on
the material de~cribed in thi6 e~ample which had
been molded and hea~ed for two hour~ at 250C but
not annealed at 200C. ~odulu~-temperature data
revealed a semi-crystalline product ~ith a distinct
~ry6talline ~odulu~ plateau. The mea~ured 1% ~ecant
~odulus values at 200C, 225C. and 250C
re6pectively were 9,340 p6i; 8,100 psi: and 6,000
p6i . The cry6talline melting point deter~ined from
the ~odulus-temperature data wa6 285C.
Calorimetric data were obtained by heating to 400C
at 10C/min under N2 on the DuPont 990 The~mal
D-13783
lZ~7;~8~
- Z2 -
Analyzec. Cry~tallinity was pcesent. The
ccy~tallina melting point was 283C and the heat o~
fusion was 7.5 cal./gc.
The cesult6 of example~ 3 and 4 indicate
that plasticization of the polymec of Example 1
leads to an impcovement in the enviconmental stress
crack resistance.
D-13783
