A novel aromatic amine terminated trifunctional polyoxyalkylene urea which is useful as an epoxy curing agent is disclosed and is prepared in a two step process comprising reacting a triamine or a triol with a diisocyanate to form an intermediate product and subsequently reacting the intermediate with a diprimary amine in the presence of an alcohol solvent.

FIELD OF THE INVENTION 
This invention relates to derivatives of polyoxyalkylene triamines. More 
particularly, this invention relates to novel compositions of matter 
comprising aromatic amine terminated trifunctional polyoxyalkylene ureas, 
prepared in two steps by reacting a triamine with a diisocyanate to form 
an intermediate containing a urea-linkage which is then reacted with an 
aromatic diamine, such as diethyltoluene diamine to form the novel 
composition. In the case of certain low molecular weight triamines where 
problems with gelation are encountered, a second embodiment affords a two 
step process for reacting a trifunctional polyether triol with a 
diisocyanate in the presence of a tin catalyst to form a prepolymer 
containing a urethane-linkage which is then reacted with a diamine. 
BACKGROUND OF THE INVENTION 
A number of curing agents for epoxy resins are known in the art, as well as 
a variety of methods for preparing epoxy curing compositions. Related, 
copending U.S. patent application Ser. No. 07/078,308 contains an 
extensive survey of art in this area. The invention described in that 
application concerns novel polyamidopolyamines. The products are prepared 
by the sequential reaction of an aliphatic or aromatic di-primary amine 
with a reaction product of at least a molar excess of an aromatic or 
aliphatic dicarboxylic acid with a polyoxyethylene, a polyoxypropylene or 
a poly(oxyethylene/oxypropylene)diamine or triamine. The reaction takes 
place at a temperature of about 150.degree.-250.degree. C. 
The references found fail to disclose any urea-linked trifunctional 
aromatic amine terminated compositions. Urea linkages are desirable 
because they are more stable and, in general, add more toughness to a 
polymer. 
The present invention, using low temperatures produces a triamine 
derivative composition which is terminated with aromatic amines and 
contains urea linkages. Further, formation of the product does not require 
a catalyst when high molecular weight triamines are the reactants. It was 
observed that in the case of low molecular weight triamines there were 
problems with gelation. However, in an alternate embodiment trifunctional 
polyether triols were used instead of triamines and reacted at fairly mild 
temperatures in the presence of a tin catalyst to form trifunctional 
aromatic amines in two steps while avoiding problems with gelation. 
These compositions are useful for applications such as epoxy coatings. The 
products are especially adapted for use in Reaction Injection Molding 
because their reactivity with isocyanates is very suitable. Other uses may 
be apparent to those skilled in the art. 
SUMMARY OF THE INVENTION 
In accordance with the foregoing, the present invention provides a method 
of preparing an isocyanate terminated, urea-linked intermediate and the 
compositions formed therefrom by reacting the intermediate with a diamine. 
More specifically there is provided a two-step method for the preparation 
of an aromatic amine terminated trifunctional polyoxyalkylene urea which 
comprises reacting a polyoxyalkylenetriamine and a diisocyanate to form an 
intermediate which is reacted with a diamine in the presence of an alcohol 
solvent at ambient temperature or lower and atmospheric pressure to form a 
novel aromatic amine terminated composition. 
In the second embodiment there is provided a two step synthetic route for 
the preparation of trifunctional aromatic amines which comprises reacting 
a trifunctional polyether triol or {lower M.W. triamine} and a 
diisocyanate in the presence of a tin catalyst to form a prepolymer which 
is reacted with a diamine in the presence of an alcohol solvent at mild 
temperatures and atmospheric pressure. 
DETAILED DESCRIPTION 
According to the present invention trifunctional prepolymers with an 
isocyanate termination can be reacted with a diamine to form a product 
terminated with aromatic amines and useful as an epoxy curing agent. The 
product can be derived without a catalyst under very mild conditions. With 
the triols or low molecular weight triamines a tin catalyst and slightly 
higher temperatures help provide the desired results. 
The aromatic amine terminated trifunctional polyoxyalkylene ureas of the 
present invention are reaction products which may generally be 
characterized as compositions represented by the following formula: 
##STR1## 
wherein R represents an ethoxy, a propoxy or an ethoxy/propoxy group 
having an average molecular weight of about 200 to about 7000. The product 
of the second embodiment is similar and can be represented as follows: 
##STR2## 
The novel compositions are essentially the reaction product of: 
(1) a triamine of the formula 
##STR3## 
wherein A represents the nucleus of an oxyalkylation susceptible 
trihydric alcohol containing about 3 to 6 carbon atoms and w, y and z are 
numbers and the average value of the sum of w, y and z is from about 10 to 
about 100; and in the second embodiment wherein a triol is used, it can be 
represented as follows: 
##STR4## 
(2) an alkyl diisocyanate; and (3) a diprimary amine of the formula 
EQU H.sub.2 N-R"--NH.sub.2 
wherein R" represents an aromatic group having an average molecular weight 
of about 72 to about 500 and containing from about 6 to about 35 carbon 
atoms, wherein said triamine and diisocyanate are reacted in a first step 
to form an intermediate which is subsequently reacted with said diamine in 
the presence of an alcohol solvent at a temperature of from about 
0.degree. C. to 100.degree. C. 
In the process of this invention a series of novel compositions of products 
containing T-5000 or T-3000 urea-linked aromatic amines have been prepared 
by the following exemplified reaction: 
##STR5## 
In the second embodiment a simple synthetic route to prepare trifunctional 
aromatic amines from the coupling reaction or prepolymer (I) and

A has 
been disclosed as follows: 
##STR6## 
THE TRIAMINE STARTING MATERIAL 
As stated above, the triamine useful herein can be represented by structure 
(3) above. 
Examples of appropriate polyoxypropylene triamines that may be used as 
starting materials for the present invention include triamines sold by 
Texaco Chemical Co. as JEFFAMINE.RTM. T-series products having the formula 
referred to above. An example of such a product having an average 
molecular weight of about 3000 wherein A represents a triol nucleus is 
JEFFAMINE.RTM. T-3000 amine and a product having an average molecular 
weight of about 5000 wherein A represents a glycerol nucleus and the 
product contains about 85 moles of propylene oxide is JEFFAMINE.RTM. 
T-5000 amine. 
THE TRIFUNCTIONAL POLYETHER POLYOL STARTING MATERIAL 
As stated above, the polyether polyol useful herein can be represented by 
structure (4) above. 
Examples of appropriate polyols that may be used as starting materials for 
the present invention include trifunctional polyether triols sold by 
Texaco Chemical Co. as THANOL.RTM. polyols having the formula referred to 
above. An example of such a product having an average molecular weight of 
about 5000 is THANOL.RTM. G-5000, Texaco product number GA84060383. 
THANOL.RTM. G-5000 is a trifunctional polyether triol which is a precursor 
to JEFFAMINE.RTM. T-5000. The JEFFAMINE.RTM. T-series products have the 
formula: 
##STR7## 
wherein A represents the nucleus of an oxyalkylation susceptible trihydric 
alcohol containing about 3 to 6 carbon atoms and w, y and z are numbers 
and the average value of the sum of w, y and z is from about 10 to about 
100; and in the G-series precursors each of the amine groups is replaced 
by a hydroxy group. Another polyether triol having an average molecular 
weight of about 400 wherein propylene oxide is added to trimethylolpropane 
is a Texaco product which is a precursor to JEFFAMINE.RTM. T-403. 
THE ISOCYANATE REACTANT 
The isocyanate component for the present invention may be any suitable 
isocyanate having the desired functionality. Alkyldiisocyanates work well. 
The organic diisocyanate can be an aliphatic or an aromatic or a mixture 
thereof. Although diisocyanates are preferred, other higher 
polyisocyanates can be used in combination with diisocyanates and/or 
monoisocyanates. 
Diisocyanates which work in the invention for producing triamines 
containing urea linkages include isophorone diisocyanate (IPDI), 
p-tetramethylxylene diisocyanate (TMXDI), m-tetramethylxylene 
diisocyanate, hexamethylene diisocyanate (HMDI), toluene diisocyanate, 
diphenylmethane diisocyanate and the like. The suitability of these 
diisocyanates is demonstrated in the examples and they can be represented 
by the following formulas: 
##STR8## 
SOLVENT 
A solvent is desirable for carrying out the invention. A solvent is useful 
in both steps of the invention and is essential for the second step in 
order to avoid gel formation. The solvent is preferably an alcohol. 
Suitable solvents are those which are relatively unreactive toward 
isocyanate groups. Generally suitable solvents are polar or those having a 
high dielectric constant. Examples of suitable polar solvents include 
methanol, ethanol, isopropanol and tert-butanol. Good results were 
obtained using isopropanol and t-butanol. 
THE DIAMINE REACTANT 
In accordance with the present invention, the intermediate reaction product 
is reacted with a diamine in the second step of the invention. The diamine 
is suitably an aromatic di-primary amine. 
Such di-primary amines can be represented by the formula: 
EQU H.sub.2 N-R"--NH.sub.2 
wherein R" represents an aromatic group having an average molecular weight 
of about 72 to about 500 and containing from about 6 to about 35 carbon 
atoms. 
R" may suitably be a phenyl, a alkyl substituted phenyl, a cycloalkyl 
substituted phenyl group, etc. 
Representative di-primary amines that may be used include diamino benzenes, 
toluene diamines, diethylphenyl diamines and diethyltoluene diamine. 
The examples demonstrate the usefulness of diethyltoluene diamine in the 
present invention. 
CATALYST 
Where a trifunctional polyether polyol or lower molecular weight triamine 
is reacted with a diisocyanate the presence of a catalyst facilitates the 
reaction. A suitable catalyst should contain a Group IVA metal. The Group 
IVA metal which is preferred is tin. A variety of tin-containing metals 
will work in the reaction, including, but not limited to dialkyl 
dicarboxylates and stannous carboxylates. Preferred tin-containing 
compounds are dialkyltin carboxylates such as dibutyltin dilaurate 
[(C.sub.4 H.sub.9)S.sub.n (OCOC.sub.10 H.sub.20 CH.sub.3).sub.2 ]. The 
effectiveness of dibutyltin dilaurate is demonstrated in Examples 10-14. 
METHOD 
In accordance with the invention demonstrated in Examples 1 to 9, the 
triamine is added dropwise to a reaction mixture containing diisocyanate 
and optionally an alcohol in the first step. 
The adduct of the above mixture is then transferred into a dropping funnel 
and added into a solution containing a di-primary amine and alcohol. The 
second reaction is exothermic and may require cooling. 
The temperatures used in the first step are mild and preferably from 
0.degree. C. to about 50.degree. C. Atmospheric pressure is suitable. 
Where a triol is used the mixture in the first step should be heated to a 
pot temperature of about 50.degree. C. to about 120.degree. C. The very 
low temperatures are not sufficient in this embodiment. However, in the 
second step where the prepolymer is reacted with a diamine, a mild 
temperature in the range of 0.degree.-50.degree. C. is sufficient. 
The product can be characterized by end-group analysis using nmr, IR and 
titration methods. The products may be liquid, semisolid or solid. 
The aromatic amine terminated trifunctional polyoxyalkylene ureas of the 
instant invention demonstrate the desirable flexibility of polymers over 
comparable epoxy curing compositions in the art. 
The present invention will be further illustrated by the following examples 
which are only for the purpose of illustration and are not to be regarded 
as limiting the invention in any way.