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Description  |
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This invention relates to poly(arylene sulfide) compositions exhibiting
improved curing characteristics and improved high temperature properties.
In accordance with another aspect, this invention relates to arylene
sulfide copolymers containing alkyl groups on some of the repeating units
in the polymer chain which copolymers exhibit more facile curing
properties than similar compositions without the presence of alkyl
substituent groups. In accordance with another aspect, this invention
relates to blends of arylene sulfide copolymers containing alkyl groups on
some of the repeating units to yield a polymeric composition which cures
more readily than poly(arylene sulfide) resins without alkyl groups. In
accordance with a further aspect, this invention relates to coated
structures comprising a substrate and an arylene sulfide copolymer
containing alkyl groups on some of the repeating units as the coating
composition. In accordance with still another aspect, this invention
relates to laminate structures comprising a plurality of layers having an
arylene sulfide copolymer containing a minor proportion of
alkyl-substituted cyclic repeating units in the polymer chain as the
bonding material for the laminate.
Accordingly, an object of this invention is to provide improved heat
curable poly(arylene sulfide) compositions.
Another object of the invention is to provide poly(arylene sulfide) coating
compositions exhibiting improved high temperature properties.
A further object of the invention is to provide laminates exhibiting
improved high strength and flexural modulus properties.
A further object of this invention is to provide poly(arylene sulfide)
compositions exhibiting improved cure characteristics.
Other objects, aspects, and the several advantages of the invention will be
apparent to those skilled in the art upon a study of the specification and
appended claims.
In accordance with the invention, heat curable arylene sulfide copolymers
exhibiting enhanced cure rates and thermal stability properties are
provided comprising arylene sulfide copolymers having in the polymer chain
a minor amount of alkyl-substituted cyclic repeating units and a major
amount of cyclic repeating units free of alkyl substituents.
In accordance with another embodiment of the invention, poly(arylene
sulfide) blends having improved cure properties are provided comprising an
arylene sulfide homopolymer and an arylene sulfide copolymer having a
minor amount of alkyl-substituted cyclic repeating units and a major
amount of cyclic repeating units free of alkyl substituents.
In accordance with still another embodiment of the invention, heat curable
arylene sulfide copolymers containing minor but substantial amounts of
alkyl-substituted cyclic repeating units in the copolymer chain are used
as coating compositions and as bonding agents for laminate structures.
In this application, the term "homopolymer" is used in its customary sense
to denote polymeric materials prepared, except for minor amounts of
incidental impurities, from a single monomer. The term "copolymer" is used
to denote polymeric materials prepared from two or more monomers and thus,
for convenience, also extends to terpolymers and higher combinations. The
term "polymer" is used broadly to denote homopolymers as well as
copolymers as defined above. The term "polymer blend" denotes, in the
customary sense, a combining of two or more polymers at a stage subsequent
to the polymerization stage but not necessarily subsequent to the curing
stage. The term "mole percent alkyl-substituted repeating unit" is used to
denote the total amount of such a moiety in a given composition based on
the total composition regardless of whether the composition is a copolymer
or is a blend of polymers, such as a blend of an alkyl-subtituted
copolymer and a non-alkyl-containing homopolymer.
I. ARYLENE SULFIDE COPOLYMERS CONTAINING ALKYL GROUPS
Copolymers of this invention can be prepared in high yield by contacting a
mixture of polyhalo-substituted cyclic compounds, at least one such
compound containing one or more nuclearly-substituted alkyl group, and at
least one such compound without alkyl substituents, with an alkali metal
sulfide in a polar organic compound at an elevated temperature.
Polyhalo-substituted compounds useful in this invention are represented by
the following formulae:
##SPC1##
wherein each X is a halogen selected from the group consisting of chlorine,
bromine, iodine, and fluorine with chlorine being preferred; wherein each
Y is either hydrogen or an alkyl group containing from one to four carbon
atoms, preferably hydrogen and/or methyl group; and wherein Z is either a
carbon atom or a nitrogen atom. The X's and Y's in a particular compound
can be either alike or different. The number m is an integer having the
value form 2 to 6. The number n is an integer having the value from 1 to
4. The number p is a positive integer having the value 4-n if Z is a
carbon atom or the value 3-n if Z is a nitrogen atom. The number q is an
integer having the value from 1 to 5. The values of n and q for each
cyclic nucleus in a compound may be alike or different. The numbers m, n,
and q are selected such that each compound contains at least two, and
preferably only two, halogen atoms per molecule. Compounds of formula I
contain from 6 to 12 carbon atoms per molecule and preferably from 6 to 8.
Compounds of Formula II contain from 9 to 16, and preferably 9 to 12,
carbon atoms per molecule. Compounds of formula III contain from 12 to 18
and preferably 12 to 14 carbon atoms per molecule.
Examples of polyhalo-substituted compounds represented by the above
formulae useful as monomers of the present invention include
p-dichlorobenzene, 2,4-dichlorotoluene, 2,5-dichloro-p-xylene,
1-n-butyl-2,5-dibromobenzene, 1,4-diethyl-2,5-dibromobenzene,
1,3,5-trifluoro-2,4,6-triethylbenzene, hexachlorobenzene,
2,6-dichloronaphthalene, 1,4-dichloro-7,8-diethylnaphthalene,
1,4-dibromo-3,5,7-triethylnaphthalene,
2-n-butyl-6-ethyl-4,8-diiodonaphthalene, 4,7-dichloroquinoline,
2-methyl-3,5,7-tribromoquinoline,
2,5-diethyl-8-n-propyl-2,3,6-trifluoroquinoline, 4,4'-dichlorobiphenyl,
3,3'-dibromo-5,5'-dimethylbiphenyl, 3,3'-diiodo-4,5'-tri-n-propylbiphenyl,
and the like.
The polymers of this invention can be generally prepared as described in
U.S. Pat. No. 3,354,129. The molar ratio of polyhalo-substituted compounds
to metal sulfide will generally be in the range 0.9/1 to 2/1. The amount
of polar organic compound can vary over a wide range from about 100 to
2500 ml per mole of metal sulfide. The reactants and polar organic
compound are contacted in any suitable stirred or unstirred reactor at a
temperature of from about 125.degree. to 450.degree. C, preferably from
175.degree. to 350.degree. C. The reaction time can be whatever is
necessary to convert a substantial portion of the reactant to polymer and
will be primarily dependent on reaction temperature and reactant
reactivity.
The alkali metal sulfides useful in this invention are represented by the
formula M.sub.2 S which includes the monosulfides of lithium, sodium,
potassium, rubidium, or cesium including either anhydrous or hydrated
forms. The preferred sulfide reactant is sodium sulfide and its hydrates.
The polar organic compounds employed according to the invention are
selected from amides, lactams, sulfones, etc. Specific examples of such
compounds are hexamethylphosphoramide, tetramethylurea, N,N'-ethylene
dipyrrolidone, N-methyl-2-pyrrolidone, caprolactam, N-ethylcaprolactam,
sulfolane, dimethylacetamide, and the like. N-Methyl-2-pyrrolidone (NMP)
is preferred.
The polymer, which is soluble in the hot reaction mixture in some
instances, can be isolated from the crude reaction mixture by any
convenient means, such as by cooling the mixture to room temperature or
slightly above, washing vigorously and repeatedly with water, separating
organic and aqueous phases by any suitable means, such as decantation,
filtration, etc., and drying the polymer. Alternatively, the crude
reaction mixture can be used without the above-described isolation scheme
by simply removing by filtration, etc., the insoluble residues, such as
sodium chloride, from the hot reaction mixture or by first treating the
hot crude reaction mixture with an agent, such as carbon dioxide, to
precipitate the soluble alkali metal ions as the insoluble carbonates
followed by filtration, etc., of the insoluble residues. The resulting hot
homogeneous solution of polymer in organic solvent can then be used
directly to cast films for coatings or for impregnating carbon, metal or
glass fibers or cloth for the preparation of high strength composites.
The composition of the mixture of polyhalo-substituted reactants, which
include alkyl-substituted reactants, will be determined to a large extent
by the end-use to which the cured copolymer is to be put. Copolymers
containing lower amounts of alkyl groups, e.g., from 1 to about 25 mole
percent alkyl-substituted cyclic repeating units, provide useful coatings
for articles in which some degree of flex is required since the cured
coating can be flexed without breaking or cracking. Particularly effective
results are obtained when 2-10 mole percent of alkyl-substituted repeating
units are present.
Polymers containing higher amounts of alkyl groups, e.g., from 25 to about
50 or more molar percent alkyl-substituted cyclic repeating units, provide
harder and less flexible materials which are useful in more rigid
articles.
The mole percent of alkyl-substituted repeating units in the copolymer
refers to the actual amounts present in the polymer chain as determined by
any suitable analytical method such as infrared spectroscopy. However, for
convenience, the mole percent is ordinarily computed from the ratio of
monomers in this high conversion copolymerization reaction.
The improvement of this aspect of the invention is arylene sulfide
copolymers having enhanced cure rates and enhanced thermal stabilities
compared to poly(arylene sulfides) without alkyl substituents. For
example, a phenylene sulfide homopolymer prepared using p-dichlorobenzene
cures in the air at 700.degree. F (371.degree. C) in 30 minutes. A
comparable copolymer prepared using 6 mole percent 2,4-dichlorotoluene
with p-dichlorobenzene cures to a comparable state of cure of 600.degree.
F (316.degree. C) in 15 minutes.
Cure temperatures for the copolymers of this invention will generally be in
the range 500.degree.-750.degree. F for whatever time produces the desired
state of cure. From several minutes to several hours, for example, 0.1-24
hours, will generally be adequate to cure the polymers of this invention
at the temperatures specified. The enhanced thermal stability and cure
rate are observed in polymers cured in air or other oxygen-containing gas,
as well as under vacuum or inert atmosphere conditions, though air curing
is preferred.
II. BLENDS OF ARYLENE SULFIDE COPOLYMERS CONTAINING ALKYL-SUBSTITUTED
CYCLIC REPEATING UNITS WITH OTHER POLY(ARYLENE SULFIDE) RESINS.
Another aspect of this invention pertains to blends of the above-described
copolymers with other poly(arylene sulfides) which do not contain alkyl
groups for the purpose of obtaining a compositon with enhanced cure rates
and thermal stability compared to the poly(arylene sulfides) without alkyl
groups.
Any of the arylene sulfide copolymers containing alkyl-substituted
repeating units described above are useful in this aspect of the
invention. Copolymers containing from 1 to about 50 or more mole percent
monomeric units containing alkyl groups can be used as curing aids for
non-alkyl-containing polymers. The final application for the blend will
determine to a large extent the composition and amount of the copolymer
used in the blend. For example, blends containing higher amounts of alkyl
groups, e.g., from 20 to about 40 mole percent alkyl-substituted cyclic
units, prepared using relatively large amounts of copolymer containing a
substantial portion of alkyl-substituted monomer units when cured will be
hard and more brittle than a blend containing smaller amounts of alkyl
groups, e.g., from 1 to about 10 mole percent alkyl-substituted cyclic
units, prepared using either large amount of low alkyl-containing
copolymer or small amounts of high alkyl-containing copolymer. The latter
blend will be more flexible and ductile than the former.
Generally speaking, sufficient alkyl-containing copolymer is blended with a
non-alkyl-containing polymer to provide 1-40 mole percent
alkyl-substituted cyclic repeating units in the total blend. Blends
containing 1-25 mole percent, preferably 2-10 mole percent, of such units
yield products of greater flexibility.
Poly(arylene sulfide) resins such as those generally described in U.S. Pat.
No. 3,354,129 not containing alkyl groups can be blended with the
copolymers of this invention. For example, blends of poly(phenylene
sulfide) or poly(biphenylene sulfide) with copolymers prpepared using
p-dichlorobenzene and 2,4-dichlorotoluene result in compositions which
cure faster and at lower temperatures than the poly(phenylene sulfide) or
poly(biphenylene sulfide) alone.
Blending of the polymers may be accomplished by any of a variety of ways,
such as solution blending, slurry blending, dry blending, etc.
Cure temperatures for the blends of this invention will generally be in the
range 500.degree.-750.degree. F for whatever time is required to produce
the desired state of cure. From several minutes to several hours, for
example, 0.1-24 hours, will generally be adequate to cure the blends of
this invention at the temperatures specified. The enhanced cure rate is
observed in polymers cured in air or other oxygen-containing gas, under
vacuum or under inert atmosphere, though air-curing is preferred, being
generally faster.
III. HIGH-STRENGTH AND THERMALLY STABLE COMPOSITIONS FROM COPOLYMERS OR
BLENDS THEREOF IN COMBINATION WITH VARIOUS SUBSTRATES
The fast-curing copolymers and blends of this invention can be used to
prepare high-strength and thermally stable compositions by coating
substrates, such as steel or aluminum, and by impregnation of fibers or
cloth of materials such as carbon, metal or glass with the copolymers or
blends of this invention followed by curing under conditions appropriate
for the polymers employed.
It is known in the art (U.S. Pat. No. 3,354,129) that a number of fillers,
such a s graphite, carbon black, titania, glass fibers, metal powders,
magnesia, asbestos, clays, wood flour, cottom floc, alpha cellulose, mica,
etc., can be used with poly(arylene sulfides). Of particular importance in
this invention is the discovery that polymers of this invention filled
with carbon or glass fibers exhibit greater thermal stability than filled
polymers which do not contain alkyl groups. Composites consisting of
carbon, metal or glass cloth impregnated with polymers of this invention
exhibit unusually high strength, as well as exceptional thermal stability.
Fibers of carbon or glass can be conveniently added to the polymerization
system prior to or subsequent to the polymerization step in which case
they are isolated with the polymer. Alternatively, carbon, glass or metal
fibers or cloth can be added to a hot solution or a slurry of the polymer.
Typical isolation, coating, molding, or curing procedures are employed to
isolate or use the resulting filler polymer.
Single layers or multiple layers of fibers, cloth or fabric made from
cotton, glass or metal can be impregnated with a hot solution or slurry of
the desired copolymer or blend of this invention. Removal of solvent or
dispersant, such as by evaporation, and molding and curing the resulting
laminate gives strong, thermally stable composites useful as jet engine
blades or cases, Wankel engine apex seals, helicopter blades, etc.
The porportion of such carbon, glass or metal materials to the copolymers
or polymer blends of the present invention will vary according to the
desired properties of the resulting composite. Ordinarily the weight ratio
of such polymeric materials to such reinforcing agents will be in the
range of 1:10 to 10:1.
Coating of the copolymers or polymer blends of this invention containing,
if desired, one or more of the above-described additives onto a substrate,
such as steel or aluminum, is accomplished by techniques known in the art
such as by applying the polymer to the substrate in the form of a slurry
in any suitable inert liquid or in the form of a powder, such as by
dusting or by a fluidized bed process. Subsequent curing as described
above results in a tough, thermally stable coating.
EXAMPLE I
The following run (Run 1) illustrates the preparation of a copolymer from
98 mole percent p-dichlorobenzene (DCB) and 2 mole percent
2,4-dichlorotoluene (DCT) in conjunction with sodium sulfide hydrate
containing 38 weight percent water.
To a two-gallon steel reactor were charged 955 gm sodium sulfide hydrate
containing 38 weight percent water and 2.5 liters N-methyl-2-pyrrolidone
(NMP). Heating and nitrogen purging were begun. Water (202 ml) was
condensed from the vent line during which the pot temperature increased to
405.degree. F. To the hot solution in the reactor was added a hot
(175.degree.-200.degree. F) previously prepared solution of 1102.5 gm
p-dichlorobenzene and 24.2 gm 2,4-dichlorotoluene in 500 ml NMP. Pressure
within the reactor after all ingredients were charged was 40 psig. The
system was maintained at 475.degree. F for three hours with continuous
stirring. Maximum pressure during the run was 135 psig. After cooling, a
light-gray liquid was obtained which was washed four times with deionized
water and dried at about 212.degree. F under vacuum. Polymer (897 gm; this
yield is higher than theory -- not known why) was recovered with 1.45
weight percent ash, 0.08 inherent viscosity, and 536.degree. F melting
point (by differential thermal analysis).
EXAMPLE II
The following runs illustrate the preparation of a copolymer from 96.1 mole
percent p-dichlorobenzene and 3.9 mole percent 2,4-dichlorotoluene with
sodium sulfide hydrate containing 38 weight percent water.
Runs 2 and 3 were conducted generally as described in Example I but using
1080 gm p-dichlorobenezene and 48.3 gm 2,4-dichlorotoluene. Results are
tabulated in Table I.
TABLE I
______________________________________
Run Polymer Ash, Inh. M.P.
No. Wt. % Theory % Visc. .degree. F
______________________________________
2 737 92.5 .89 .07 527
3.sup.a
771 96.7 1.4 .02 509
______________________________________
.sup.a Malfunction occurred in heating and cooling units.
These data show polymer obtained with slightly lower melting point than
obtained in Example I.
EXAMPLE III
The following runs illustrate the preparation of copolymers from 94.1 mole
percent p-dichlorobenzene and 5.9 mole percent 2,4-dichlorotoluene with
sodium sulfide hydrate.
Runs 4 to 11 were conducted generally as described in Example I but using
1058 gm p-dichlorobenzene and 72.5 gm 2,4-dichlorotoluene. Results are
tabulated in Table II.
TABLE II
______________________________________
Run Polymer Ash, Inh. M.P.,
No. Wt. % Theory % Visc. .degree. F
______________________________________
4 700 87.3 522
5 729 91.0 .67 .08 522
6 679 84.6 1.05 .11 522
7 703 87.7 .89 .09 522
8 680 84.8 .71 .09 522
9 774.sup.a
96.5 1.1 .08 522
10 726.sup.a
90.6 .74 .07 522
11 753.sup.a
93.9 .72 .06 523
______________________________________
.sup.a A different lot of 2,4-dichlorotoluene was used in Runs 9, 10 and
11 than was used in Runs 1-8.
These data indicate that polymer was obtained in lower yield (comparing
runs 4-8 with Runs 1-3 all of which employed the same lot of
2,4-dichlorotoluene) having slightly lower melting point than Runs 2 and
3.
EXAMPLE IV
The following runs illustrate the preparation of copolymers from 91.5 mole
percent p-dichlorobenzene and 8.5 mole percent 2,4-dichlorotoluene with
sodium sulfide hydrate.
Runs 12 and 13 were conducted generally as described in Example I but using
1030 gm p-dichlorobenzene and 105 gm 2,4-dichlorotoluene. Results are
tabulated in Table III.
TABLE III
______________________________________
Run Polymer Ash, Inh. M.P.,
No. Wt. % Theory % Visc. .degree. F
______________________________________
12 685 85.3 .59 .08 509
13 760 94.6 .96 .05 511
______________________________________
These data indicate that polymer was obtained having lower melting point
than was observed in Example III.
EXAMPLE V
The following runs illustrate the preparation of copolymers from 78.3 mole
percent p-dichlorobenzene and 21.7 mole percent 2,4-dichlorotoluene with
sodium sulfide hydrate.
Runs 14 to 17 were conducted generally as described in Example I but using
884 gm p-dichlorobenzene and 266 gm 2,4-dichlorotoluene. Results are
tabulated in Table IV.
TABLE IV
______________________________________
Run Polymer Ash, Inh. M.P.,
No. Wt. % Theory % Visc. .degree. F
______________________________________
14 736 90.1 1.4 .05 428
15 a .54 .04 426
16 a .91 .04 a
17 742 91.0 .69 .03 430
______________________________________
.sup.a Not determined.
These data indicate that polymer was obtained having lower melting point
than observed in Example IV.
EXAMPLE VI
The following runs illustrate the preparation of copolymers of varying
compositions prepared from p-dichlorobenzene and 2,5-dichloro-p-xylene
(DCX) with sodium sulfide hydrate.
Runs 18 to 23 were conducted generally as described in Example I but using
appropriate amounts of p-dichlorobenzene and 2,5-dichloro-p-xylene.
Results are tabulated in Table V.
TABLE V
__________________________________________________________________________
Run DCB/DCX.sup.a
Polymer Ash, Inh. M.P.,
No.
Wt. Mole Wt. % Theory
% Visc.
.degree. F
__________________________________________________________________________
18 1102/26.2
98/2 619 77.7 .51 .15 550
19 1080/52.5
96.1/3.9
548 68.8 .43 .1 531
20 1058/79
94.1/5.9
537 67.3 .73 .12 523
21 1030/125
91.5/8.5
689 86.4 1 .12 504
22 884/289
78.3/21.7
b .33 .04 b
23 884/289
78.3/21.7
734 92.2 .63 .05 433
__________________________________________________________________________
.sup.a p-Dichlorobenzene/2,5-dichloro-p-xylene ratio.
.sup.b Not determined.
The data indicate that the desired copolymers were prepared. The decreasing
melting points with increasing amount of 2,5-dichloro-p-xylene is
indicative of decreasing crystallinity in polymers.
EXAMPLE VII
The following runs illustrate the preparation of terpolymers of varying
compositions prepared from p-dichlorobenzene, 2,4-dichlorotoluene, and
dichloronaphthalene (a mixture consisting of 20 weight percent mixed
dichloronaphthalene isomers, 72 weight percent 1-chloronaphthalene and 7
weight percent naphthalene) with sodium sulfide hydrate.
Runs 24 and 25 were conducted generally as described in Example I but using
appropriate amounts of p-dichlorobenzene (DCB), 2,4-dichlorotoluene (DCT),
and dichloronaphthalene (DCN). Results are tabulated in Table VI.
TABLE VI
__________________________________________________________________________
Run DCB/DCT/DCN.sup.a
Polymer
Ash, Inh. M.P.,
No.
Wt. Mole Wt. % Visc.
.degree. F
__________________________________________________________________________
24 904/60/221.7
80/5/15
759 .23 .01 437
25 1014/60.3/73.8
90/5/5
746 b b 504
__________________________________________________________________________
.sup.a p-Dichlorobenzene/2,4-dichlorotoluene/dichloro-naphthalene ratio.
.sup.b Not determined.
These data indicate that the desired polymers were prepared. Increasing the
amount of dichloronaphthalene in the charge with a corresponding decrease
in the amount of p-dichlorobenzene gave lower melting point of the
resultant polymer.
EXAMPLE VIII
The following runs illustrate the preparation of terpolymers of varying
compositions prepared from p-dichlorobenzene (DCB), 2,4-dichlorotoluene
(DCT) and 4,7-dichloroquinoline (DCQ) with sodium sulfide hydrate.
Runs 26 and 27 were conducted generally as described in Example I but using
appropriate amounts of p-dichlorobenzene, 2,4-dichlorotoluene and
4,7-dichloroquinoline. Results are tabulated in Table VII.
TABLE VII
__________________________________________________________________________
Run
DCB/DCT/DCQ.sup.a
Polymer Ash, Inh. M.P.,
No.
Wt. Mole Wt. % Theory
% Visc.
.degree. F
__________________________________________________________________________
26 1014/60/74
90/5/5
816 100 .72 .06 518
27 904/60/223
80/5/15
b -- .71 .06 486
__________________________________________________________________________
.sup.a p-Dichlorobenzene/2,4-dichlorotoluene/4,7-dichloro-quinoline ratio
.sup.b Not determined.
These data indicate that the desired polymers were prepared. Increasing the
amount of 4,7-dichloroquinoline in the charge with a corresponding
decrease in the amount of p-dichlorobenzene gave lower melting point of
the resultant polymer.
EXAMPLE IX
The following run illustrates the preparation of a terpolymer from 80 mole
percent p-dichlorobenzene, 15 mole percent m-dichlorobenzene and 5 mole
percent 2,4-dichlorotoluene with sodium sulfide hydrate.
Run 28 was conducted generally as described in Example I but using 904 gm
p-dichlorobenzene, 165 gm m-dichlorobenzene and 60 gm 2,4-dichlorotoluene.
Polymer was obtained (725 gm, 90.6% of theory) having 1.99 percent ash,
0.06 inherent viscosity and 432.degree. F melting point. The melting point
is considerably lower than polymers prepared using only the para isomer of
dichlorobenzene (see Example III) indicating successful preparation of the
desired polymer.
EXAMPLE X
A test was devised to determine the state of cure of the above-described
polymers and other poly(arylene sulfides) as a function of cure time and
temperature. From the data obtained in this test relative rates of cures
were obtained.
The test consisted of degreasing with acetone coldrolled steel panels 3 in.
.times. 6 in. .times. .035 in. and heating them in a gas-oxygen flame to a
blue-gray color. After the panels were cooled to room temperature, three
coats of the formulation (3 parts by weight polymer, 1 part by weight
titanium dioxide and 6 parts by weight propylene glycol mixed in a Waring
blender) were applied with a coating rod. Each coat of formulation was
baked at the specified time and temperature later. After the third coat
was baked, the coated panel was annealed for two hours at 450.degree. F
and then allowed to stand overnight at room temperture. The coated panels
were bent 180.degree. over a 3/16-inch diameter rod, then straightened,
and the elongated portions were examined at 20-.times. magnification.
Numerical ratings of 1 to 5 correspond to the following observations:
______________________________________
Rating Observation
______________________________________
1 No cracking on elongation portion.
2 Occasional microcracks.
3 Numerous microcracks and some cracking
which may be barely visible to the
unaided eye.
4 Cracks are continuous and easily visible.
5 Complete rupture of coating.
______________________________________
Application of the above-described test to the polymer in Examples I to IX
gave the results tabulated in Table VIII.
TABLE VIII
__________________________________________________________________________
Polymer Coating Test.sup.a
Run Mole
No. Monomers
Ratio 700-30
700-15
600-30
600-15
550-30
__________________________________________________________________________
1 DCB/DCT
98/2 1 1 4 4
2 DCB/DCT
96/4 1 1 1 4
3 DCB/DCT
96/4 1 1 1 3
4 DCB/DCT
94/6 1 1 1 1 4
5 DCB/DCT
94/6 1 1 1 1
6 DCB/DCT
94/6 1 1 1 3
7 DCB/DCT
94/6 1 1 1 1
8 DCB/DCT
94/6 1 1 1 1
9 DCB/DCT
94/6 1 1 1 1
10 DCB/DCT
94/6 1 1 1 1
11 DCB/DCT
94/6 1 1 1 1
12 DCB/DCT
91.5/8.5
5 1 1 1 4
13 DCB/DCT
91.5/8.5
2 1 1 1
14 DCB/DCT
78/22 (Failed) 4.sup.b
15 DCB/DCT
78/22 5 5 3 3
16 DCB/DCT 78/22 (Not determined)
17 DCB/DCT 78/22 5 5 5 5
18 DCB/DCX 98/2 1 1 1 3
19 DCB/DCX 96/4 1 1 1 1
20 DCB/DCX 94/6 1 1 1 1
21 DCB/DCX 91.5/8.5
5 5 1 1
22 DCB/DCX 78/22 (Not determined)
23 DCB/DCX 78/22 (Not determined)
24 DCB/DCT/DCN
80/5/15
5 4 5.sup.b
25 DCB/DCT/DCN
90/5/5 2 5.sup.b
26 DCB/DCT/DCQ
90/5/5 1 2
27 DCB/DCT/DCQ
80/5/15
5 3 1.sup.b
28 DCB 100/0 2.sup.c
3 3
__________________________________________________________________________
.sup.a Column headings are cure temperature in .degree. F - cure time in
minutes for each coat.
.sup.b Cured at 500.degree. F for 30 minutes.
.sup.c Cured at 700.degree. F for 10 minutes.
Several conclusions can be drawn from the data in Table VIII. Copolymers
prepared from p-dichlorobenzene containing up to about 9 mole percent
2,4-dichlorotoluene cure at temperatures and/or times lower than are
required for the curing of poly(phenylene sulfide). For example, Runs 4-13
shown that polymers prepared using from 6 to 8.5 mole percent
2,4-dichlorotoluene cure at 600.degree. F in 15 minutes to a state
comparable to that reached by poly(phenylene sulfide) at 700.degree. F for
10 minutes. Higher amounts of 2,4-dichlorotoluene resulted in overcuring
at higher temeratures (Runs 12 to 17) as shown by increasing brittleness.
From Runs 18 to 23 describing polymers prepared from p-dichlorobenzene and
2,5-dichloro-p-xylene the same conclusions can be reached as were reached
for polymers using 2,4-dichlorotoluene as comonomer with
p-dichlorobenzene. The data derived from the terpolymers of Runs 24 to 27
are not conclusive but indicate lower cure temperature-time requirements
than the control homopolymer.
EXAMPLE XI
The polymer prepared in Run 4 using 94.1 mole percent p-dichlorobenzene and
5.9 mole percent 2,4-dichlorotoluene was further examined in the coating
tests generally described in Example X. A single coat of polymer (as a
slurry in propylene glycol without filler) was applied to an aluminum
panel and was cured at 600.degree. F for varying lengths of time.
Following baking the coatings were annealed for the usual two hours at
450.degree. F. Curing for from one to 24 hours produced coatings which all
gave a "1" rating after being bent (see Example X). These data indicate
that this polymer was not overcurred or embrittled during prolonged
heating at 600.degree. F.
EXAMPLE XII
The following runs illustrate the use of the polymer prepared in the Run 14
using 21.7 mole percent 2,4-dichlorotoluene in blends with commercial
poly(phenylene sulfide).
Runs 28 to 31 were conducted generally as described in Example I with
polymer blends of varying compositions. The data are tabulated in Table
IX.
TABLE IX
______________________________________
Run Blend Coating Test
No. Homo.sup.a
Co.sup.b
600-45 600-30 600-15
______________________________________
28 1 0 3 3 3
29 95 5 3 3
30 9 1 1 2 3
31 3 1 1 2
32 1 1 5 2
______________________________________
.sup.a Homopolymer -- poly(phenylene sulfide), parts by weight in blend.
.sup.b Copolymer -- Run 14, parts by weight.
These data indicate that addition of a copolymer prepared using 78.3 mole
percent p-dichlorobenzene and 21.7 mole percent 2,4-dichlorotoluene to
poly(phenylene sulfide) resulted in a blend having lower cure temperature
and time requirements than the homopolymer alone. Using up 25 weight
percent copolymer in the blend gave blends containing up to about 6 mole
percent monomeric units with methyl groups. These blends exhibited
increasing cure rates with increasing amounts of copolymer. At 50 weight
percent copolymer, corresponding to about 11 mole percent
methyl-containing monomer units, the blend overcured and embrittled in 30
minutes curing at 600.degree. F.
EXAMPLE XIII
The polymer prepared in Run 14 using 21.7 mole percent 2,4-dichlorotoluene
was used to impregnate carbon fibers. The following runs illustrate the
use of carbon fiber and polymer in a 2 to 1 weight ratio, respectively,
under various curing conditions to prepare high strength compositions.
Runs 33 to 44 were conducted by first dissolving the polymer from Run 14 in
boiling N-methyl-2-pyrrolidone (NMP) using amounts to prepare 10 to 20
weight percent solutions (e.g., 6 gm polymer in 40 ml NMP). The hot
polymer solution was poured over hot (approximately 400.degree. F)
unidirectional carbon fibers (.00033 in. diameter, 250,000 to 350,000 psi
tensile strength, 50 .times. 10.sup.6 to 60 .times. 10.sup.6 tensile
modulus), the weight of which was double the polymer weight (e.g., 12 gm
carbon fibers for 6 gm polymer). Evaporation of the NMP under vacuum at
210.degree. to 250.degree. F gave a solid composition which was cured
under conditions described in Table X. Results are tabulated in Table X.
TABLE X
__________________________________________________________________________
Flex.
Flex. Mod. Strength,
Run Cure Post-Cure psi .times. 10.sup.-.sup.3
psi
No. Temp.
Time
Atm.
Temp.
Time Atm.
RT 300F
500F at 500F
__________________________________________________________________________
33 600F
2 hr
Air
-- -- -- 21,293 124,750.sup.a
34 600F
2 hr
Air
-- -- -- 22,844
1,438
35 600F
4 hr
Air
-- -- -- 30,580
6,892 9,510
36 600F
4 hr
Vac.
-- -- -- 21,106
3,400 4,050
37 600F
6 hr
Vac.
-- -- -- 25,454
6,246 9,430
38 600F
2 hr
Air
600F
23 hr
Air
8,840.sup.b
6,858.sup.b
22,170
39.sup.c
600F
4 hr
Air
500F
98 hr
Air
19,264
19,900
17,021
37,260
40 600F
4 hr
Vac.
500F
16 hr
Air
21,730
19,875
10,290
20,400
41 600F
4 hr
Vac.
600F
4 hr
Air
23,365
11,235 | | |
