Note: Descriptions are shown in the official language in which they were submitted.
~3~ 60 IN 495
'J
`~ This invention relates to-~e~ i~e~ e base
coating compositions. More particularly, it relates to
such coating compositions which have water as the sole or
major solvent constituent.
Resinous coating compositions in the form of
varnishes and enamels in which for ease of application
the polymer is dissolved in compatible solvents are
well known. Among the most useful coating compositions
~ /Ya~n ,d~
are those which are based on ' ~ . Polyamideimide
coating compositions form flexible and durable films and
are particularly useful as wire enamels~ varnishes, adhesives
p~/Y~ ofe ~vn~
for laminates, paints and the like. Such ~o~amide~-mi~e
base coating compositions are particularly noted for
their long term high temperature capability of the order
of 220C which, in addition to their other qualities, makes
them particularly useful in electrical insulating applications -~
such as for maynet wire enamels. ~his is as compared to
the usual polyester and polyesterimide base coating
compositions which do not have such highly continuous heat
resistance. Since polyamideimides have heretofore been
prepared using relatively expensive organic solvents,
the economic use of amideimide coatings has been inhibited.
It has been customary, for example, to use such polyamideimide
compositions as overcoats over less expensive polyester
or polyesterimide base coats. It would be most desirable
and the high temperature characteristics of polyamideimide
coating compositions would be more fully realized
commercially were cheaper solvents made available. It is
a primary object of this invention to provide polyamideimide
coating compositions which contain relatively inexpensive
solvent systems which are not only more economic but which
do not produce undesirable concentrations of pollutants
~3~ 60 ~l 495
when they evaporate durin~ curiny of the resin base.
As pointed out above, polyamideimide compositions
are well known, being directed w.idely in the literature and
in patents such as U. S. 2,421,021 dated May 27l 1947;
3,260,691 dated July 12, 1966; 3,471,444 dated October
7, 1969; 3,518,230 dated June 30, 1970; 3,817,926 dated
June 18, 1974 and 3,847,878 as well as in the foreign paten~
literature as illustrated, for example, by British patent
57018S8 .
As exemplary of the preparation of polyamideimides,
there can be reacted together a carboxylic anhydirde and an
organic primary amine to form an amideimide prepolymer, there
being reacted with this prepolymer a polyisocyanate to
produce a relatively hiyh molecular welght block polymer
which in solution affords the desirable film-forming
and other characteristics inherent in polamideimidesO
Any of a number of carboxylic anhydrides can be used
in making polyamideimides including but not limited to the
following, among others, which will occur to those skilled in
the art: trimellitic anhydride; 2,6,7-naphthalene
tricarboxylic anhydride' 3,3',4-diphenyl tricarboxylic
anhydride; 3,3',4-benzophenone tricarboxylic anhydride;
1,3,4-cyclopentane tetracarboxylic anhydride; 2,2',3-aiphenyl
tricarboxylic anhydride; diphenyl sulfone 3,3',4-tricarboxylic
anhydride; diphenyl isopropylidene 3,3',4-tricarboxylic
anhydride; 3,4,10-perylene tri.carboxylic anhydride;
3,4-dicarboxyphenyl 3-carboxyphenyl ether anhydride; ethylene
tricarboxylic anhydride; l,2,5-naphthalene tricarboxylic
anhydride, etc. The tricarboxylic acid materials can be
characteri:zed by the followiny formula:
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I HO-~-R C \
\C~
where R is a trlvalent organic radical.
The polyamines useful in the above connection
are well known and may be expressed by the formula
II X - R" ~---{NH2)n : :
where R" is an organic radical and n is at least 2 and
X is hydrogen, an amino group or organic group including ..
those also containing at least one amino groupO
The polyamines useful in the above connection
can also be express by the formula
III R'~'- (NH2)n
where R'l' is a member selected from the class consisting
of oryanic radicals of at least two carbon atoms (both
halogenated and unhalogenated)~including but not limited
to, e.g., hydrocarbon radicals of up to 40 carbon atoms9
and groups consisting of at least two aryl residues attached
to each other through the medium of a member selected
from the class consisting of an alkylene radical of from
1 to 10 carbon atoms, -5-, -SO2- O , and -O-, etcO, and
n is at least 2.
Among the specific useful amines, alone or in
admixture, are the following:
p-xylene diamine
bis(4-amino-cyclohexyl)methane
hexamethylene diamine
heptamethylene diamine
octamethylene diamine
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1 ~ 2~ 60 IN 495
nonamethylene diamine
decamethylene diamine
3-methyl heptamethylene diamine
4,41-dimethylheptamethylene diamine
2,11-diamino-dodecane
1,2-bis-(3-amino-propoxy)ethane
2,2-dimethyl propylene diamine
3-methoxy-hexamethylene diamine
2,5-dimethylhexamethylene diamine
2,5-dimethylheptamethylene diamine
5-methylnonamethylene diamine
1,4-diamino-cyclo-hexane
1,12-diamino-octadecane
2,5-diamino-1,3,4-oxadiazole
2 (CH2)3O(cH2)2o(cH2)3NH2
H2N(CH2)3S(cH2)3NH2
~2N(CH2)3N(CH3)(c~2)3NH2
meta-phenylene diamine
para-phenylene diamine
4,4'-diamino-diphenyl propane
4,4'-diamino-diphenyl methane
benzidine
4,4'-diamino-diphen~l sul~ide
4,4'-diamino-diphenyl sul~one
3,3'-diamino-d.iphenyl sul:Eone
4,4'-diamino-diphenyl ether
2,6-diamino-pyridine
bis(4-amino-phenyl)diethyl silane
bis(4-amino-phenyl)diphenyl silane
bis(4-amino-phenyl)phosphine oxide
4,4'-diaminobenzophenone
bis~4-amino-phenyl)-N-methylamine
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^` ,~ 60 IN 495
~3~
bls(4-aminobutyl)tetramethyldisiloxane
1,5-diaminonaphthalene
3,3'-dimethyl-4,41-diamino-biphenyl
3,3'-dimethoxy benzidine
2,4-bis(beta-amino-t butyl)toluene
toluene diamine
bis(para-beta-amino-t-butyl-phenyl)ether
para-bis(2-methyl-4-amino-pentyl)benzene
para-bis(l,l-dimethyl-5-amino-pentyl)benzene
m-xylylene diamine
polymethylene polyaniline
Any polyisocyanate, that is, any isocyanate having two or
more isocyanate groups, whether blocked or unblocked, can
be used in ma};iny polyamideimides. ~locked isocyanates
using as the blocking constituent phenols or alcohols, among
others, can be used and in general provide a higher
molecular weight final material which is advantageous as,
for example, in varnishes. On the other hand, the unblocked
isocyanates provide more flexible final materials. At
any rate, the blocking material must be evaporated off as
much as possible and there is no advantage from the purely
reaction point of view to using the blocked material
except as stated above. Typical of the blocked polyiso-
cyanates is Mondur S wherein mixtures of 2,4- and 2,6-
tolylene diisocyanate are reacted with trimethylol
propane and blocked by esterification with phenol in th
proportions of three moles of iosycanate, one mole of
trimethylol propane, and three moles of phenol. In
Mondur SH the isocyanate groups of mixed 2,4- and 2,6-toly-
lene diisocyanate are blocked by es~erification with
cresol. Among the specific polyisocyanates which are
usefule alone or in admixture are the following:
~ 398~ 60 IN 495
tetramethylenediisocyanate
hexamethylenediisocyanate
1,4-phenylenediisocyanate
1,3-phenylenediisocyanate
1,4-cyclohexylenediisocyana~e
2,4-tolylenediisocyanate
2,5-tolylenediisocyanate
2,6-tolylenediisocyanate
3,5-tolylenediisocyanate
4-chloro-1,3-phenylenediisocyanate
l-methoxy-2,4-phenylenediisocyanate
l-methyl-3,5-diethyl-2,6-phenylenediisocyanate
1,3,5-triethyl 2,4-phenylenedii.socyanate
l-methyl-3,5-diethyl-2,4-phenylenediisocyanate
l-methyl-3,5-diethyl-6-chloro-2,4 phenylenediiso-
cyanate
6-methyl-2,4-diethyl-5-nitro-1,3-phenylenediiso-
cyanate
p-xylylenediisocyanate
m-xylylenediisocyanate
4,6-dimethyl-1,3-xylylenediisocyanate
1,3-dimethyl-4,5-bis-(b-isocyanatoe-thyl)-benzene
3-(a-isocyanatoethyl~-phenylisocyanate
1-methyl-2,4-cyclohexylenediisocyanate
4,4'-biphenylenediisocyanate
3,3'-dimethyl-414l-bi.phenylenediLsocyanate
3,3'-dimethoxy-4,4'-biphenylenediisocyanate
3,3'-diethoxy-4,4-biphenylenediisocyanate
1,1-bix-(4-isocyanatophenyl)cyclohexane
4,4'-diisocyanato-diphenylether
4,4'-diisocyanato-dicyclohexylmethane
4,4'-diisocyanato-diphenylmethane
~3~ 60 IN ~95
4,~'-diisocyanato-3,3'-dimethyldiphenylmethane
4,4'-diisocyanato-3,3'-dichlorodiphenylmethane
4,4'-diisocyanato-diphenyldimethylmethane
1,5-naphthylenediisocyanate
1,4-naphthylenediisocyanate
4,4',4"-triisocyanato-triphenylmethane
2,4,4'-triisocyanato-diphenylether
2,4,6-triisocyanato-1-methyl-3,5-diethylbenzene
o-tolidine-4,4'-diisocyanate
m-tolidine-4,4'-diisocyanate
benzophenone-4,4'-diisocyanate
biuret triisocyanates
polymethylenepolyphenylene lsocyanate
Generally speaking, a slight molar excess of
carboxylic acid anhydride and organic polyamine is heated
to about 200C to 245C in an inert atmosphere and solvent
as above, driving off the water formed and forming an
amideimide group containing prepolymer. The polyisocyanate
is then added and reacted to form a block amide-imide pre-
polymer of relatively high molecular weight. It can be
cured as by heating to form flexible film or coatings.
Alterna-tively, the carboxylic anhydride and organic
diamine can be reacted in equimolar proportions, still
providing desirable flexible films or coatings, wire
enamels, paints, laminate adhesives and the like.
As taught, or example, in UO S. patent
3,817,926, up to 75 mole percent of the carboxylic anhydride
can be replaced by substituted or unsubstituted aliphatic
anhydride or diacid such as oxalic, maleic, succinic,
glutaric, adipic, pimelic, suberic, azelaic, sebacic and
dodecanedioic as well as unsaturated materials including
maleic and fumaric materials, among others. Such acids
-- 7
~23~ 60 IN ~95
can be expressed by the formula
IV ~IOOC - Rl - COOH
where R' is a divalent satuxated or unsaturated aliphatic
group or one containing a carbon-to-carbon double bond
and having from about one to 40 carbon atoms, while the
anhydrides can be expressed by
o
~ ,.:
/rc
V P~ /0
' ~ `
The normal organic solvents used for such
materials include cresols or cresylic acid, phenol,
xylene, N-methylpyrrolidone, dimethylformamide, dimethyl
sulEoxide, dimethylacetamide, and the like which not only
tend to pollute the atmosphere during the curing process
but which in some instances are toxic, flammable or may
- cause serious chemical burns.
The above exemp]ary preparation method for
polyamideimides is just that, and there are taught in the
above patents and the voluminous general literature in
this art including but not limited to New Linear Polymers,
Lee et al, McGraw-~ill, 19~7.
In addition to avoiding costly organic .solvents
which are presently used in connection with polyamideimide
coating compositions, it would be most desirable to use
a solvent such as water which would not only be cheaper
but would be more acceptable ecologically.
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60 IN 495
3~
Those features of the invention which are believed
to be novel are set forth with particularity in the claims
appended hereto. The invention will, however, be better
understood and further advantages and ob~ects thereof
appreciated from a consideration of the following description.
Broadly speaking, in the practice of the present
invention, the polamideimide such as the powdered solid is
mixed with a secondary or tertiary amine or mixtures along
with water as a solvent to which there may be added relatively
small amounts of organic solvent in certain instances, the
mixture being heated to a temperature of about 80C until
a clear solution is obtained. Primary amines can also be
used but are generally not reactive enough for an economic
process. During the process the amine splits the imide
ring of the polyamideimide.
The amines or amine group containing materials.
useful in connection with the present invention are
preferably tertiary amines and include, among others,
dimethylethanolamine, triethanolamine, phenylmethyle-
thanolamine, butyldiethanolamine, phenyldiethanolamine,
phenylethylethanolamine, methyldiethanolamines, and
triethylamine. Secondary amines are also useful. The
present coating compositions may be made in a wide range
o~ solids contents to suit any particular application con-
sistant with coating ease and capability. Generally, the
solids content can range from about 10 percent to ~0 percent
by weight solids or even more from a practical point of
viewO
Polyamideimides which have up to about 20
percent free carboxyl groups can be used. However, free
carboxyl groups are not essential to the invention.
The following examples illustrate the practice
~ 60 IN 495
oE the present invention, it being understood that they
are exemplary only. All parts are by weight unless
otherwise indicated.
Example 1
Ten parts oE commercial polyamideimide powder,
specifically Amoco AI-10 was combined with 35 parts of water,
5 parts of N-methylpyrrolidone and 10 parts of the tertiary
amine dimethylethanolamine. The mixture was heated to 80C
until a clear amber color solution was obtained. A portion
of the liquid was coated on a metal panel, the coating
being cured for one hour at 200C. The p~nel was bent 180
without cracking. Another panel so coated was cured at
175~C for 30 minutes and at 200C for 15 minutes to give
a clear, flexible film.
Example 2
Twenty-five parts by weight of polyamideimide powder
were combined with 60 parts of water, 15 parts of N-methyl-
pyrrolidone and 23 parts of dimethylethanolamine. The
mixturP was placed on a roller for mixing and heated to 80C
until a clear solution was obtained. This material was
coated on a metal panel and cured for one hour at 135C
and then at 240 for 15 minutes. A clear, flexible film
was obtained which did not crack when the panel was doubled
upon itself.
Example 3
A mixture of 397 parts of 33 percent by weight
solids solution of polyamldeimide and N-methylpyrrolidone was
heated to 150C and 112 parts of dimethylethanolamine
added thereto. The contents were cooled to 100C and 487
parts of water added. The resulting solution was clear
and had a solids content of 25.3 percent with a viscosity
of 1430 centistokes at 25C. This wire enamel solution
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60 IN 495
was applied to 18 ~WG copper wire using seven passes to
produce a 3.0 mil film buildwp. The enamel was cured in
a 15 foot high gasfired oven, the running speed being
50 ft. per minutes with a top oven temperature of 480C
and a bottom -temperature of 270C. The resulting magnet
wire had a cut-through of 325C and otherwise acceptable
characteristics.
Example 4
. . .
A 33 percent solutlon of polyamideimide in
the amount o~ 397 parts was heated to 150C and 50 parts
of di-N-butylamine added thereto. The contents were
stirred and allowed to cool to 100C and 107 parts of
water were added. The resulting clear solution had
a solids content of 27.1 percent and a ViSCQSity of Z-5.
When this material was cured on aluminum at 100C for
10 minutes and 160C for 10 minutes and finally at 20QC
for 30 minutes, the resulting film was clear and did
not fail during a 90 crease.
Example 5
A container was charged with 10 parts of
polyamideimide powder, there being added thereto 13.5 parts
of dimethylethanolamine and 76.5 parts of water. The
material was heated to 90C with stirring to give a
clear, viscous solution. When a portion of the above
solution was cured on an aluminum substrate for one
hour at 200C, a flexible film was ohtained.
There are provided by the present invention
polyamideimide base coating compositions which are
characterized by good coating characteristics and parti-
cularly by their increased cut through temperature. In
addition, such materials are partially or wholly soluble
in water, representing a saving in solvent cost as well
60 IN 495
~12~
as being ecologically acceptable. While the materials
are particularly useful as magnet wire enamels and as
varnishes, they can also be used Eor preparing laminates
of layered materials, composites of :Eibers, powders,
varnishes and the like and for coating purposes in
general.
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