 |
Description  |
|
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the condensation of isocyanates with carboxylic
acids or anhydrides to form imides, amides, or amide-imides and is more
particularly concerned with the use of cyclic phosphorus compounds as
catalysts for the condensation.
2. Description of the Prior Art
The reaction of isocyanates with carboxylic acids or anhydrides to form
imides and amides, and, more particularly, the reaction of organic
diisocyanates with dicarboxylic acids or dianhydrides, or anhydrides
containing free carboxyl groups, to form polyamides, polyimides or
polyamide-imides, is well-known; see, for example, U.S. Pat. Nos.
3,592,789; 3,541,038; and 3,708,458. The use of catalysts to promote these
condensations is also known; see, for example, U.S. Pat. No. 3,701,756.
We have now found that the above reactions can be catalyzed in highly
satisfactory manner using a group of heterocyclic phosphorus compounds
which have not hitherto been suggested for this purpose. Our findings are
particularly surprising in view of the known behaviour of this class of
phosphorus compounds as catalysts for the conversion of isocyanates to
carbodiimides. We have found that the compounds in question can be used to
catalyze the above reactions of isocyanates with carboxylic acids and
derivatives thereof without any significant concurrent formation of
carbodiimides except in certain instances.
SUMMARY OF THE INVENTION
This invention comprises an improved process for catalyzing the reaction
between an organic isocyanate and a member selected from the class
consisting of organic carboxylic acids and organic carboxylic anhydrides
wherein the improvement comprises employing as the catalyst a cyclic
phosphorus compound selected from those having the formulae:
##STR1##
WHEREIN A, B, C, AND D IN EACH INSTANCE ARE INDEPENDENTLY SELECTED FROM
THE GROUP CONSISTING OF HYDROGEN, HALOGEN, LOWER-ALKOXY, PHENOXY,
LOWER-HYDROCARBYL, AND HALO-SUBSTITUTED LOWER-HYDROCARBYL; THE DOTTED
LINES REPRESENT A DOUBLE BOND BETWEEN CARBON ATOM 3 AND ONE OF THE CARBON
ATOMS 2 AND 4; Y is hydrogen attached to whichever of carbon atoms 2 and 4
is not part of said double bond; R is selected from the group consisting
of lower-hydrocarbyl and halo-substituted lower-hydrocarbyl, and Z is
selected from the class consisting of oxygen, sulfur, and NR', wherein R'
is lower-hydrocarbyl.
The term "halogen" is used throughout this specification and claims in its
generally accepted sense as embracing chlorine, bromine, iodine, and
fluorine.
The term "lower-alkoxy" as used throughout the specification and claims
means alkoxy from 1 to 6 carbon atoms, inclusive, such as methoxy, ethoxy,
propoxy, butoxy, pentyloxy, hexyloxy and isomeric forms thereof. The term
"lower-hydrocarbyl" means the monovalent radical obtained by removing one
hydrogen atom from a parent hydrocarbon having from 1 to 6 carbon atoms,
inclusive. Illustrative of such hydrocarbyl groups are alkyl such as
methyl, ethyl, propyl, butyl, pentyl, hexyl and isomeric forms thereof;
alkenyl such as vinyl, allyl, butenyl, pentenyl, hexenyl, and isomeric
forms thereof; cycloalkyl such as cyclobutyl, cyclopentyl and cyclohexyl;
and phenyl.
The term "halo-substituted lower-hydrocarbyl" means lower-hydrocarbyl as
above defined wherein one or more of the hydrogen atoms in said
hydrocarbyl has been replaced by halogen. Illustrative of halo-substituted
lower-hydrocarbyl are chloromethyl, trichloromethyl, trifluoromethyl,
2-chloroethyl, 2,3-dichlorobutyl, 2-chlorobutenyl, 2-bromohexyl,
4-chlorophenyl, 3-fluorophenyl, 2-chloropropenyl, and the like.
DETAILED DESCRIPTION OF THE INVENTION
The essentially novel feature of the present invention resides largely in
the employment of a heterocyclic phosphorus compound of the formulae (I),
(II) or (III) as catalyst in the known reaction of an isocyanate with a
carboxylic acid or anhydride to form the corresponding amide, imide or
amide-imide. The procedure employed in carrying out the process of the
invention is essentially that employed hitherto in this particular
condensation with the exception that the heterocyclic phosphorus compound
is present in the reaction mixture in catalytic amount corresponding to
about 0.0001 mole to about 0.1 mole per mole of isocyanate. Preferably the
amount of heterocyclic phosphorus catalyst employed is of the order of
about 0.005 mole to about 0.05 mole per mole of isocyanate.
The process of the invention is applicable to the reaction of a
monoisocyanate with a mono-carboxylic acid or a dicarboxylic acid
anhydride to form a monomeric amide or imide, as well as to the reaction
of a di- or polyisocyanate with a polyfunctional carboxylic acid or
polyanhydride thereof as well as monomers containing both carboxylic
anhydride and free carboxylic acid groups to form polyamides, polyimides
and polyamide-imides.
The process of the invention is accomplished conveniently by bringing
together the necessary reactants and the catalyst under substantially
anhydrous conditions, advantageously, but not necessarily, in the presence
of an inert organic solvent. By "inert organic solvent" is meant an
organic solvent which is inert under the conditions of the reaction, i.e.
does not enter into reaction with either of the reactants or the catalyst
present in the reaction nor interfere with the desired progress of the
reaction in any significant manner. Examples of such inert organic
solvents are benzene, toluene, xylene, decalin, tetralin, chlorobenzene,
dichlorobenzene, hexane, heptane, octane, dodecane, tetrahydrofuran,
pyridine, dioxane, dimethylsulfoxide, dimethylformamide,
N,N-dimethylacetamide, tetramethylene sulfone, dimethylsulfone,
tetramethylurea, hexamethylphosphoramide, and the like.
The temperature employed in the reaction mixture can vary over a wide range
from about 20.degree. C. to about 250.degree. C. but the reaction
temperature is advantageously within the range of about 100.degree. C. to
200.degree. C. The most appropriate temperature to employ for any given
combination of reactants can be readily determined by a process of trial
and error.
The progress of the reaction is generally followed readily by standard
analytical techniques, for example, by observing the appearance of
absorption bands highly characteristic of the imide or amide linkages, as
the case may be, using infrared spectroscopic analysis. When the reaction
is observed to be complete, the desired product can be isolated from the
reaction mixture by routine procedures, for example, by evaporation of the
inert organic solvent, if one is used, followed by purification of the
residue, if desired or necessary. Illustratively, when the product is
monomeric, it can be purified by distilling out the heterocyclic
phosphoric catalyst and subjecting the residue to recrystallization,
distillation, and the like. When the product is a polymer, it can be
purified after removing the catalyst as above, by trituration with inert
organic solvent to remove low molecular weight by-products, or, where the
polymer is soluble in an organic solvent, by precipitation from solution.
The isocyanate and the carboxylic acid or anhydride which are employed in
the process of the invention are generally employed in substantially
stoichiometric proportions.
The isocyanates which can be employed in the process of the invention
include any of the known mono- and polyisocyanates such as those disclosed
by Siefken, Ann. 562, 122-135 (1949). Illustrative of the isocyanates
which are employed in the process of the invention are organic
monoisocyanates such as phenyl isocyanate, p-tolylisocyanate, o-tolyl
isocyanate, m-xylyl isocyanate, .alpha.-naphthyl isocyanate, octadecyl
isocyanate, benzyl isocyanate, allyl isocyanate, cyclohexyl isocyanate,
p-nitrophenyl isocyanate, o-chlorophenyl isocyanate, m-chlorophenyl
isocyanate, p-fluorophenyl isocyanate, 4,4,4-trichloro-2-bromobutyl
isocyanate, and the like, and polyisocyanates such as 2,4-tolylene
diisocyanate, 2,6-tolylene diisocyanate, 4,4'-methylenebis(phenyl
isocyanate), dianisidine diisocyanate, tolidine diisocyanate,
hexamethylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate),
m-xylene diisocyanate, 1,5-naphthalene diisocyanate,
1,4-diethylbenzene-.beta.,.beta.'-diisocyanate and other di- and higher
polyisocyanates such as those listed in the tables of Siefken, supra.
Mixtures of two or more of the above isocyanates can be used, such as
mixtures of the 2,4- and 2,6-isomers of tolylene diisocyanate, mixtures of
the 2,4'- and 4,4'-isomers of methylenebis(phenyl isocyanate) and the
like. In addition to the 4,4'-methylenebis(phenyl isocyanate) or mixtures
of the 2,4'-isomer and 4,4'-isomer thereof which are employed as the
isocyanate component, there can also be used modified forms of these
isocyanates. For example there can be used 4,4'-methylenebis(phenyl
isocyanate), or an admixture thereof with a minor amount of the
2,4'-isomer, which has been treated to convert a minor proportion,
generally less than 15% by weight of the starting material, to an artefact
of said starting material. For example, the polyisocyanate component (I)
can be methylenebis(phenyl isocyanate) which has been converted to a
stable liquid at temperatures of about 15.degree. C. and higher using, for
example, the processes described in U.S. Pat. Nos. 3,384,653, 3,394,164
and 3,394,165.
In addition to the various modified forms of methylenebis(phenyl
isocyanate) exemplified above there can also be employed as the
polyisocyanate component a mixture of methylenebis(phenyl isocyanate) with
polymethylene polyphenyl isocyanates of higher functionality. Such
mixtures are generally those obtained by phosgenation of corresponding
mixtures of methylene bridged polyphenyl polyamines. The latter, in turn,
are obtained by interaction of formaldehyde, hydrochloric acid and primary
aromatic amines, for example, aniline, o-chloroaniline, o-toluidine and
the like. Such polyamines and polyisocyanates prepared therefrom are known
in the art, see, for example, U.S. Pat. Nos. 2,683,730; 2,950,263;
3,012,008, and 3,097,191; Canadian Pat. No. 665,495; and German Pat. No.
1,131,877. Preferred polymethylene polyphenyl polyisocyanates are those
containing from about 35% to about 60% by weight of methylenebis(phenyl
isocyanate). The polymethylene polyphenyl isocyanate available
commercially under the trademark PAPI.RTM. is typical of this type of
polyisocyanate.
The carboxylic acid intramolecular anhydrides which are employed in the
process of the invention can be any mono- or poly intramolecular
anhydride. Illustrative of the mono intramolecular anhydrides are phthalic
anhydride, succinic anhydride, adipic anhydride, glutaric anhydride,
citraconic anhydride, maleic anhydride, itaconic anhydride, fumaric
anhydride, naphthalene-1,2-dicarboxylic acid anhydride,
naphthalene-1,8-dicarboxylic acid anhydride, chlorendic anhydride,
1,2,3,6-tetrahydrophthalic acid anhydride, and the like. The
polycarboxylic acids which are employed in the process of the invention
contain at least two carboxylic moieties selected from the class
consisting of free carboxy groups and anhydride groups. Said
polycarboxylic derivatives are inclusive of aromatic, aliphatic,
cycloaliphatic or heterocyclic polycarboxylic acids as well as the
intramolecular and/or intermolecular anhydrides thereof, provided that, in
the case of those anhydrides which contain a single anhydride group there
is also present in the molecule at least one free carboxy group. As will
be appreciated by one skilled in the art only those polycarboxylic acids
which contain carboxy groups attached either to two adjacent carbon atoms
or to two carbon atoms which are separated from each other by a single
carbon or hetero-atom are capable of forming intra- as opposed to inter-
molecular acid anhydrides.
Any of the aforesaid polycarboxylic acids or anhydrides can be employed as
the polycarboxylic derivative in the process of the invention. As will be
apparent to the skilled chemist the nature of the recurring units in the
resulting polyimides will vary according to the structure of the starting
polycarboxylic derivative.
When the polycarboxylic acid derivative is a dicarboxylic acid which is
incapable of forming an intramolecular anhydride, the product formed in
accordance with the process of the invention is a polyamide e.g. the
product from said dicarboxylic acid and a diisocyanate would contain the
recurring unit:
##STR2##
wherein A is the hydrocarbon residue of the dicarboxylic acid starting
material and B is the hydrocarbon residue of the diisocyanate. On the
other hand, when the polycarboxylic derivative is an intramolecular or
inter-molecular anhydride which contains two or more anhydride moieties or
contains one anhydride moiety and free carboxylic acid groups capable of
intramolecular or inter-molecular anhydride formation, the product of
reaction in accordance with the process of the invention is a polyimide
e.g. the product of reaction of a diisocyanate and a polycarboxylic acid
derivative containing two intra-molecular anhydride groups would contain
the recurring unit:
##STR3##
wherein A' is the hydrocarbon residue of the dianhydride and B' is the
hydrocarbon residue of the diisocyanate.
Similarly where the polycarboxylic acid derivative contains one or more
anhydride groups in addition to a free carboxylic acid group or groups,
the polymer resulting from the process of the invention will be a hybrid
containing both amide and imide linkages.
All of the above types of polymers can be prepared in accordance with the
process hereinabove described and all fall within the scope of this
invention. Thus, by appropriate choice of the polycarboxylic acid
derivative it is possible to prepare any of a wide variety of polymers
using the single step process of the invention.
Examples of polycarboxylic derivatives which can be employed as the free
carboxylic acids or as intermolecular anhydrides formed from the same or
different acids are: isophthalic acid, terephthalic acid, trimesic acid
and phthalic acid. Examples of polycarboxylic derivatives which can be
employed as the free carboxylic acids or intramolecular anhydrides
thereof, are:
trimellitic acid and the anhydride thereof,
pyromellitic acid and the dianhydride thereof,
mellophanic acid and the anhydride thereof,
benzene-1,2,3,4-tetracarboxylic acid and the dianhydride thereof,
benzene-1,2,3-tricarboxylic acid and the anhydride thereof,
diphenyl-3,3',4,4'-tetracarboxylic acid and the dianhydride thereof,
diphenyl-2,2',3,3'-tetracarboxylic acid and the dianhydride thereof,
naphthalene-2,3,6,7-tetracarboxylic acid and the dianhydride thereof,
naphthalene-1,2,4,5-tetracarboxylic acid and the dianhydride thereof,
naphthalene-1,4,5,8-tetracarboxylic acid and the dianhydride thereof,
decahydronaphthalene-1,4,5,8-tetracarboxylic acid and the dianhydride
thereof,
4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic acid
and the dianhydride thereof,
2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic acid and the dianhydride
thereof,
2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid and the dianhydride
thereof,
2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic acid and the
dianhydride thereof,
phenanthrene-1,3,9,10-tetracarboxylic acid and the dianhydride thereof,
perylene-3,4,9,10-tetracarboxylic acid and the dianhydride thereof,
bis(2,3-dicarboxyphenyl)methane and the dianhydride thereof,
bis(3,4-dicarboxyphenyl)methane and the dianhydride thereof,
1,1-bis(2,3-dicarboxyphenyl)ethane and the dianhydride thereof,
1,1-bis(3,4-dicarboxyphenyl)ethane and the dianhydride thereof,
2,2-bis(2,3-dicarboxyphenyl)propane and the dianhydride thereof,
2,3-bis(3,4-dicarboxyphenyl)propane and the dianhydride thereof,
bis(3,4-dicarboxyphenyl)sulfone and the dianhydride thereof,
bis(3,4-dicarboxyphenyl)ether and the dianhydride thereof,
ethylene tetracarboxylic acid and the dianhydride thereof,
butane-1,2,3,4-tetracarboxylic acid and the dianhydride thereof,
cyclopentane-1,2,3,4-tetracarboxylic acid and the dianhydride thereof,
pyrrolidine-2,3,4,5-tetracarboxylic acid and the dianhydride thereof,
pyrazine-2,3,5,6-tetracarboxylic acid and the dianhydride thereof,
mellitic acid and the trianhydride thereof,
thiophen-2,3,4,5-tetracarboxylic acid and the dianhydride thereof, and
benzophenone-3,3', 4,4'-tetracarboxylic acid and the dianhydride thereof.
Other anhydrides which may be employed in the practice of the invention
are; the intermolecular anhydride of trimellitic acid 1,2-anhydride (see,
for example U.S. Pat. No. 3,155,687), the bisanhydrides disclosed in U.S.
Pat. No. 3,277,117 [e.g. 4,4'-ethylene glycol bis-anhydro trimellitate and
4,4'-(2-acetyl-1,3-glycerol)bis-anhydro trimellitate] and the di-adducts
of maleic acid or anhydride with styrene.
Illustrative of aliphatic dicarboxylic acids are glutaric, adipic, azelaic,
pimelic, sebacic, decanedioic dodecanedioic, and brassylic acids.
The heterocyclic phosphorus compounds of formulae (I), (II) and (III) which
are employed as catalysts in the process of the invention are known in the
art, as are the methods for their preparation. Thus the compounds of
formula (I) in which R is oxygen or sulfur are described in U.S. Pat. Nos.
2,663,737 and 2,663,738 and the corresponding compounds of formula (II) in
which R is oxygen or sulfur are described in U.S. Pat. No. 2,663,739. The
compounds of formulae (I) and (II) wherein R represents NR' (wherein R' is
lower-hydrocarbyl) can be prepared from the corresponding compounds in
which R represents oxygen by reacting the latter with the appropriate
hydrocarbyl isocyanate R'NCO using the conditions described by G. Aksnes
et al., J. Acta Chem. Scand. 23, 2697, 1969. The compounds of formula
(III), which are employed in the process of the invention, and processes
for their preparation, are described by S. E. Cremer et al., J. Org. Chem.
32, 4066 (1967).
The imides and amides produced in accordance with the process of the
invention are, for the most part, known in the art and are useful in ways
which are familiar to the art. For example, many of the monoimides,
particularly those derived from chlorendic acid anhydride, are known to be
useful as insecticides, fungicides, and herbicides. Illustratively,
N-arylphthalimides such as N-phenylphthalimide, exhibit growth-regulatory
effects and can be used for prevention of fruit drop, rooting of cuttings,
formation of parthenogenic fruit, and the like; Canadian Pat. No. 519,684.
N-arylphthalimides such as N-phenylphthalimide are also useful as
stabilizers for polysulfone resins; U.S. Pat. No. 2,643,237.
The polyamides and polyamide-imides produced in accordance with the
invention can be employed for a variety of purposes. Illustratively, they
may be shaped, for example, by machining from billets, by punching or by
making use of powdered metal techniques, into articles such as grinding
wheels, friction devices such as brakes and clutches, or they may be used
as coating compositions. Said coating compositions may be used as
impregnating resins or applied to various substrates, such as metals,
wires, woven fabrics or even to other polymeric materials.
The finding that the compounds of formulae (I), (II) and (III) will act as
catalysts for the preparation of the imides, amides and amide-imides is
highly surprising in view of the fact that the compounds in question are
known to be highly active catalysts for the conversion of organic
isocyanates to carbodiimides. Not only is the finding highly surprising,
but it is also highly useful. In particular, it is found that, by
employing the above compounds as catalysts, it is possible to produce
polyamides and polyamide-imides which have higher molecular weights and
more useful, i.e. superior, structural strength properties than those
obtainable heretofore. Further, in contrast to the most successful
catalysts hitherto employed in this art (such as sodium and potassium
methoxide), the compounds (I), (II) and (III) are not basic and show no
tendency to cause trimerization of the isocyanate as an undesirable side
reaction.
In the case of the preparation of polyimides by condensation of an organic
diisocyanate and a dianhydride it is found that the use of the
heterocyclic compounds (I), (II) or (III) as catalysts gives rise to a
polymer in which there are a substantial number of carbodiimide units in
addition to the imide units. In the case of the preparation of polyamides
and polyamide-imides no such formation of carbodiimide moieties occurs.
When the process of the invention is employed in the preparation of
polymers, the process can be conducted so as to give either cellular or
non-cellular products. The reaction between the isocyanate and the
carboxylic acid or anhydride gives rise to elimination of carbon dioxide.
The carbon dioxide can, if desired, be removed from the reaction mixture
as it is produced and, in the absence of any other added blowing agent,
the reaction will be non-cellular.
In preparing cellular products in accordance with the process of the
invention, the polyisocyanate, the polycarboxylic acid or anhydride and
the heterocyclic phosphorus catalyst (I), (II), or (III), are brought
together under foam producing conditions using additional blowing agents,
if desired, and like adjuvants commonly employed in the preparation of
polymer foams of this type.
The following examples describe the manner and process of making and using
the invention and set forth the best mode contemplated by the inventors of
carrying out the invention but are not to be construed as limiting.
EXAMPLE 1
The reaction between phenyl isocyanate and benzoic acid was investigated
without the use of a catalyst and then with a catalyst in accordance with
the invention.
A mixture of 4.8 g. (0.04 mole) of phenyl isocyanate and 4.9 g. (0.04 mole)
of benzoic acid in 50 ml. of anhydrous xylene was heated under reflux for
90 minutes. At the end of this period the infrared spectrum and an aliquot
showed the complete absence of any amide linkage. Accordingly, a solution
of 0.0658 g. (0.0005 mole) of a mixture of
1,3-dimethyl-2-phospholene-1-oxide and 1,3-dimethyl-3-phospholene-1-oxide
in 1 ml. of anhydrous xylene was added to the reaction mixture, still at
reflux, and the refluxing was continued for a further 35 minutes. The
resulting product was allowed to cool to room temperature (circa
20.degree. C.) and the solid which separated was isolated by filtration,
washed with hexane and dried. There was thus obtained 7.1 g. (90 percent
theoretical yield) of N-phenylbenzamide having a melting point of
157.degree. to 159.degree. C.
EXAMPLE 2
A mixture of 4.7 g (0.025 mole) of azelaic acid, 5.95 g. (0.05 mole) of
phenyl isocyanate, and 0.0685 g. (0.0005 mole) of a mixture of
1,3-dimethyl-2-phospholene-1-oxide and 1,3-dimethyl-3-phospholene-1-oxide
in 50 ml. of anhydrous xylene was heated under reflux for 10 minutes. At
the end of this time the evolution of bubbles had subsided. The mixture
was cooled to room temperature (circa 20.degree. C.) and 50 ml. of benzene
was added. The crystalline solid which separated was isolated by
filtration, washed with hexane (2.times.50 ml.) and dried. There was thus
obtained 7.4 g. (87.6 percent theoretical yield) of N,N'-diphenyl azelaic
acid diamide having a melting point of 173.degree.-181.degree. C.
Recrystallization from methanol raised the melting point to 185.degree. to
186.5.degree. C.
EXAMPLE 3
A mixture of 4.8 g. (0.025 mole) of trimellitic anhydride, 5.95 g. (0.05
mole) of phenyl isocyanate and 0.065 g. (0.0005 mole) of a mixture of
1,3-dimethyl-2-phospholene-1-oxide and 1,3-dimethyl-3-phospholene-1-oxide
in 50 ml. of anhydrous xylene was heated under reflux for 3.5 hours. At
the end of this time the mixture was cooled to room temperature (circa
20.degree. C.) and diluted with 25 ml. of benzene. The solid which
separated was isolated by filtration and washed with hexane (50 ml.).
There was thus obtained 7.95 g. (93 percent theoretical yield) of
N-phenyl-5-benzamidophthalimide in the form of a yellow solid having a
melting point of 260.degree. to 264.degree. C.
EXAMPLE 4
A mixture of 7.4 g. (0.05 mole) of phthalic anhydride, 5.95 g. (0.05 mole)
of phenyl isocyanate and 0.065 g. (0.0005 mole) of a mixture of
1,3-dimethyl-2-phospholene-1-oxide and 1,3-dimethyl-3-phospholene-1-oxide
in 50 ml. of anhydrous xylene was heated under reflux for 3.5 hours. At
the end of this time the mixture was cooled to room temperature (circa
20.degree. C.) and the solid which separated was isolated by filtration,
washed with hexane and dried. There was thus obtained 6.6 g. (59.1 percent
theoretical yield) of N-phenylphthalimide in the form of a crystalline
solid having a melting point of 191.degree. to 203.degree. C.
EXAMPLE 5
A mixture of 2.9 g. (0.025 mole) of maleic acid, 5.95 g. (0.05 mole) of
phenyl isocyanate and 0.065 g. (0.005 mole) of a mixture of
1,3-dimethyl-2-phospholene-1-oxide and 1,3-dimethyl-3-phospholene-1-oxide
in 50 ml. of anhydrous xylene was heated to reflux at which point the
mixture became a solid mass. The product was diluted with 25 ml. of
benzene and filtered. The solid was washed on the filter with 25 ml. of
benzene followed by 50 ml. of hexane and then dried in vacuo. There was
thus obtained 4.45 g. (66.9 percent theoretical yield) of N,N'-diphenyl
maleic acid diamide in the form of a crystalline solid having a melting
point of 303.degree. to 309.degree. C.
EXAMPLE 6
A mixture of 7.4 g. (0.05 mole) of phthalic anhydride and 5.95 g. (0.05
mole) of phenyl isocyanate and 0.097 g. (0.0005 mole) of
3-methyl-1-phenylphospholane-1-oxide in 50 ml. of anhydrous xylene was
heated under reflux for 3.5 hours. At the end of this time the mixture was
cooled to room temperature and the solid which separated was isolated by
filtration, washed with 50 ml. of xylene followed by 2.times.25 ml. of
hexane and dried. There was thus obtained 3.9 g. (34.9 percent theoretical
yield) of N-phenylphthalimide having a melting point of
204.degree.-8.degree. C.
EXAMPLE 7
A mixture of 7.4 g. (0.05 mole) of phthalic anhydride, 4.96 g. (0.05 mole)
of n-butyl isocyanate and 0.0532 g. (0.0004 mole) of a mixture of
1,3-dimethyl-2-phospholene-1-oxide and 1,3-dimethyl-3-phospholene-1-oxide
in 50 ml. of xylene was heated under reflux for 3.75 hours. The resulting
mixture was distilled to remove the xylene and the residue was distilled
under vacuum to obtain a total of 9.8 g. of semi-solid material having a
boiling point of 142.degree.-170.degree. C./0.3 mm. An aliquot of 2 g. of
this material was triturated with 50 ml. of hexane. The insoluble phthalic
anhydride (0.15 g.) was removed by filtration and the filtrate was
evaporated to dryness to yield 1.95 g. of N-n-butylphthalimide having a
melting point of 32.degree.-35.5.degree. C. On the basis of the yield from
this aliquot, it is calculated that the total amount of
N-n-butylphthalimide in the crude product was 9 g. representing an 87%
theoretical yield.
EXAMPLE 8
A mixture of 18.82 g. (0.1 mole) of azelaic acid, 19.21 g. (0.1 mole) of
trimellitic anhydride and 0.07 g. (0.00053 mole) of
1,3-dimethyl-3-phospholene-1-oxide was charged to a dry 500 ml. round
bottom flask fitted with gas inlet tube, stirrer, condenser and addition
funnel. To the mixture was added 298 ml. of tetramethylene sulfone which
had been previously distilled under vacuum. The resulting mixture was
stirred under an atmosphere of nitrogen and heated to 150.degree. C. at
which point the mixture was a clear pale yellow solution. The temperature
was maintained at 150.degree. C. while a total of 50.05 g. (0.2 mole) of
4,4'-methylenebis(phenyl isocyanate) in 60 ml. of tetramethylenesulfone
was added dropwise over a period of 6 hours and 40 minutes. The mixture
was then cooled to room temperature (circa 20.degree. C.) and poured, with
stirring, into an excess of acetone. The solid which separated was
isolated by filtration and then washed by suspending the product in water
with vigorous stirring, isolating the washed product by filtration,
resuspending the solid in acetone with vigorous stirring, and finally
isolating by filtration followed by drying. There was thus obtained 70 g.
of a polyamide-imide in which 50 percent of the recurring units had the
formula
##STR4##
and the remaining 50 percent of the recurring units had the formula
##STR5##
A sample of the polyamide-imide was dried at 170.degree. C. for 12 hours.
The inherent viscosity of this sample (0.5 percent in N-methylpyrrolidone
at 30.degree. C.) was found to be 1.25.
The above procedure was repeated and a sample of the powdered polymer so
obtained was blended with 2 percent by weight of an antioxidant (Irganox
1098) and extruded through a 1/8 inch diameter die using a Brabender
extruder. The barrel temperature in Zones 1 and 2 of the latter was
270.degree. C., in Zone 3 265.degree. C. and the temperature of the die
was 260.degree. C. The screw speed was 50 rpm with a 4:1 compression
ratio. The extruded strands were pelletized using a cutter and the
pelletized material was then injection molded using an Arburg
reciprocating screw injection molding machine to produce test bars for
examination of tensile and flexural strength properties under the
following conditions.
______________________________________
Tensile Bars
Flexural Bars
______________________________________
Temperature .degree.C.
Barrel - Zone 1
270 270
Zone 2 270 270
nozzle 270 270
mold 160 150
Injection pressure: psi
8700 10200
Injection speed setting
4.2 4.2
Screw speed 120 120
Back pressure: psi
0 0
Injection time: seconds
12 12
Mold close: seconds
35 35
______________________________________
The following physical properties of the polymer were determined using the
test bars so prepared:
______________________________________
Tensile Strength
(yield) psi 14,050
(break) psi 12,500
Tensile Modulus psi 330,000
Elongation (break) % 16.5
(yield) % 8.4
Flexural Strength psi 17,240
Flexural Modulus psi 323,600
lZOD Impact Strength
Unnotched ft. lbs/in
>20
Notched ft. lbs/in 3.04
1/4" thick bar
Heat distortion temperature
at 264 psi .degree.C. 150
______________________________________
EXAMPLE 9
The procedure described in Example 8 was repeated except that the amount of
azelaic acid was increased to 22.58 g. (0.12 mole), the amount of
trimellitic anhydride was decreased by a corresponding amount to 15.37 g.
(0.08 mole), the amount of 1,3-dimethyl-3-phospholene-1-oxide was
increased to 0.10 g. (0.00076 mole) and the amount of
tetramethylenesulfone was reduced to 164 ml. to give a mixture with 20
percent by weight of solids. In spite of the increased concentration of
solids so achieved, the final reaction mixture was still sufficiently low
in viscosity to be handled by standard stirring equipment. The resulting
polyamide-imide was worked up as described in Example 8 and a sample was
dried under vacuum at 88.degree. C. The dried sample showed inherent
viscosity (0.5 percent in m-cresol) at 30.degree. C. of 1.12. Said
polyamide-imide had 60 percent of recurring units of formula (a) [see
Example 8] and 40 percent of formula (b).
EXAMPLE 10
A mixture of 30.74 g. (0.16 mole) of trimellitic anhydride, 6.65 g. (0.04
mole) of isophthalic anhydride and 0.08 g. (0.0006 mole) of
1,3-dimethyl-3-phospholene-1-oxide was charged to a dry 500 ml. round
bottom flask fitted with gas inlet tube, stirrer, condenser and addition
funnel. To the mixture was added 192 ml. of tetramethylenesulfone which
had been previously redistilled. The resulting mixture was stirred under
nitrogen and heated to 160.degree. C. The mixture was maintained at the
same temperature with stirring while a total of 50.05 g. (0.20 mole) of
4,4'-methylenebis(phenyl isocyanate) in 60 ml. of tetramethylenesulfone
was added dropwise over a period of 5.75 hours. After the addition was
complete, the mixture was stirred for a further 10 minutes before being
poured hot into circa 3 liters of deionized water. The spaghetti-like mass
which was precipitated, was allowed to stand overnight before being
chopped up and washed by suspending in deionized water with vigorous
stirring. The washed solid was isolated by filtration and the washing step
was repeated twice with water and once with acetone and, finally, the
solid was stirred in an acetone suspension overnight. The resulting solid
was isolated by filtration and dried at 210.degree. C. for 17 hours. A
sample of the dried solid was found to have an inherent viscosity (0.5
percent in N-methylpyrrolidone) at 30.degree. C. of 0.551. Three molded
discs (2".times.1/8") were prepared by compression molding at
295.degree.-302.degree. C. under a pressure of 4450 psi. A Gehman test
(ASTM-D1053-58T) was run on a speciment of the molded material and showed
a glass transition temperature (Tg) of 263.degree. C.
The above preparation was repeated exactly as described except that the
quantities of all reactants were increased by 50 percent and the total
amount of tetramethylenesulfone was increased to 475 ml. to yield a
reaction product having 15 percent w/w solids. The polymer so obtained was
found to have an inherent viscosity (0.5 percent in N-methyl-pyrrolidone
at 30.degree. C.) of 1.28.
A solution of 15 g. of said polymer in 135 ml. of dimethylformamide was
filtered and the filtrate was used to cast 3 films employing a Gardner
film casting apparatus with a knife setting of 25 mils. The films so
obtained were predried over glass plates at 80.degree. C. for circa 3
hours before being removed and clamped on frames for a final cure at
200.degree. C. for 10 hours. The following properties were determined
using specimens of the film so obtained.
______________________________________
parallel to
perpendicular to
casting direction
casting direction
______________________________________
Tensile strength: psi
13,800 14,600
Tensile modulus: psi
342,500 331,600
Elongation at break: %
25.0 20.0
______________________________________
EXAMPLE 11
A mixture of 19.05 g. (0.1 mole) of azelaic acid, 19.21 g. (0.1 mole) of
trimellitic anhydride and 0.08 g. (0.0004 mole) of
3-methyl-1-phenyl-2-phospholene-1-oxide was charged to a dry 500 ml. round
bottom flask fitted with gas inlet tube, stirrer, condenser, and addition
funnel. To the mixture was added 214 ml. of redistilled
tetramethylenesulfone and the resulting mixture was heated under nitrogen
to 150.degree. C. with stirring. The mixture was maintained at that
temperature while a total of 50.05 g. (0.2 mole) of
4,4'-methylenebis(phenyl isocyanate) in 60 ml. of tetramethylenesulfone
was added dropwise with stirring over a period of 6.5 hours. When the
addition was complete, the reaction mixture was maintained at the above
temperature with stirring before being poured, while still hot, into an
excess of deionized water. The resulting mixture was allowed to stand for
3 days after which the solid which had precipitated was chopped up, washed
by suspending in water with vigorous stirring, filtered, washed again with
water and then with acetone, and finally suspended overnight in acetone
before filtering and drying under vacuum at 173.degree. C. for 40 hours.
The material so obtained was a copolyamide-imide characterized by the
presence of equal numbers of recurring units (a) and (b) [see Example 8].
The polyamide-imide had an inherent viscosity (0.5 percent in
N-methylpyrrolidone) of 1.10. A disc (2".times.1/8") was compression
molded at 260.degree. C. under a pressure of 4450 psi and found to have
the following physical properties: A Gehman test was run according to ASTM
D1053-58T and showed a Tg of 170.degree. C.
EXAMPLE 12
A mixture of 15.03 g. (0.09 mole) of isophthalic acid and 125 ml. of
tetramethylenesulfone was charged to a 300 ml. round bottom flask fitted
with stirrer, gas inlet tube, condenser and addition funnel. The mixture
was heated to 160.degree. C. under nitrogen with stirring and 0.07 g.
(0.00054 mole) of 1,3-dimethyl-3-phospholene-1-oxide was added. The
mixture was stirred and maintained at circa 160.degree. C. while a
solution 5.23 g. (0.03 mole) of 2,4-toluene diisocyanate in 10 ml. of
tetramethylenesulfone was added dropwise over a period of 45 minutes.
After the addition was completed, the mixture was stirred at the same
temperature for 2 hours at the end of which time the product was a clear
solution. To this solution was added 11.40 g. (0.06 mole) of azelaic acid
which was rinsed in with 40 ml. of tetramethylenesulfone. This addition
was followed by the dropwise addition, with stirring and maintenance of
the temperature at the above level, of a solution of 30.04 g. (0.12 mole)
of 4,4'-methylenebis(phenyl isocyanate) in 25 ml. of
tetramethylenesulfone. The addition was completed in 4 hours and the
residual isocyanate in the addition funnel was rinsed in using 20 ml. of
tetramethylenesulfone. After the addition was complete, the reaction
mixture was stirred for a further 1 hour at 160.degree. C. before being
poured hot into 3 l. of cold water. The solid which separated was allowed
to stand overnight before being chopped, isolated by filtration and
resuspended in water. The solid so washed was isolated by filtration, then
suspended in acetone. The suspension was stirred overnight and then
filtered, washed by suspension in acetone and then filtered and dried for
2 hours at 80.degree. C., followed by 1 hour at 110.degree. C. and 12
hours at 160.degree. C., all under vacuum. A sample of the material was
found to have an inherent viscosity (0.5 percent in m-cresol) of 0.73 at
30.degree. C.
For purposes of comparison a second run was carried out exactly as
described above except that the 1,3-dimethyl-3-phospholene-1-oxide
catalyst was repla | | |
