Imidazolidone polyetheramine strength enhancing additives of epoxy resin systems

This invention discloses the composition and preparation of imidazolidone modified polyetheramines. The alkyl polyetheramine is derived from 2-isopropylaminoethylamine and urea. N-isopropyl-2-imidazolidone is the intermediate product, which is alkoxylated and aminated to prepare the N-isopropyl imidazolidone polyetheramine. This invention also discloses the composition and preparation of oxazolidinone modified polyetheramines by reductive amination of polyols derived from 4-ethyl-4-hydroxymethyl-2-oxazolidone. The products of this invention have been tested in epoxy resin applications and improved properties have been demonstrated. These products may also be useful in polyurea applications.

BACKGROUND OF THE INVENTION 
CROSS-REFERENCE 
This application is related to U.S. application Ser. No. 07/928,583now U.S. 
Pat. No. 5,250,637, to U.S. application Ser. No. 07/928,582, now U.S. Pat. 
No. 5,288,873, and to U.S. application Ser. No. 07/984,760, now U.S. Pat. 
No. 5,238,971. 
1. Field of the Invention 
The invention relates to novel epoxy curing compositions: 
1.) an alkyl polyetheramine derived from imidazolidone(hereinafter referred 
to as IMD). 
2.) aminated, alkoxylated derivatives of hydroxyalkyl-2-oxazolidinones. 
These novel polyetheramines produce elastomers with good properties. The 
IMD derivative can be used in combination and the 
hydroxyalkyl-2-oxazolidinone derivative can be used alone or in 
combination with known polyalkyleneamine curing agents and reacted with 
multifunctional epoxy resins to produce systems which possess a level of 
flexibility and toughness not usually achieved. Due to the unique 
structure of these amines, which contain cyclic urea, cured systems show 
increased rigidity, are less extensible, and less resistant to impact than 
are systems cured with blends of other polyetheramines of equivalent 
weight. 
These novel polyetheramines make it possible to prepare curing agents 
having a broad range of molecular weights, useful in a variety of epoxy, 
polyurea, and polyamide applications. The variety of possible combinations 
and molecular weights can result in a broad range of physical properties 
in cured products. 
2. Related Art 
Various strength enhancing additives for epoxy resin systems have been 
described. These additives, known as "fortifiers", differ considerably in 
structure from those of the proposed invention. See McLean, et. al., Brit. 
Poly, J., 15, 66(1983); Garton. et. al., Poly. Eng. & Sci., 27, No. 20, 
1620(1987). 
The amination of long alkoxylated alkyl chains terminated by hydroxyl 
groups is well-known in the art. 
U.S. Pat. No. 3,654,370 to E. L. Yeakey teaches the amination of 
polyoxyalkylene polyols to form the corresponding amines by means of 
ammonia and hydrogen over a catalyst prepared by the reduction of a 
mixture of the oxides of nickel, copper and chromium. The amination is 
carried out at a temperature of 150.degree. to 275.degree. C. and 500 to 
5000 psig. 
U.S. Pat. No. 4,996,294 to Cuscurida et al. teaches a process in which an 
amine tetrol prepared by oxyalkylation of a propanediol with propylene 
oxide is catalytically aminated to provide, for example, an 
aminotetramine. The aminotetramines are useful for preparing polyurea 
products and as curing agents for epoxy resins. 
A number of patents describe catalysts for producing primary or secondary 
amines. See, for example: 
U.S. Pat. No. 4,766,245--(Raney Nickel) to Larkin & Renken; U.S. Pat. Nos. 
4,152,345& 4,153,581 to Habermann; U.S. Pat. No. 4,409,399 to H. E. Swift 
et al.; U.S. Pat. No. 3,390,184 to P. H. Moss et al.; U.S. Pat. No. 
3,373,204 to R. A. Hales et al.; U.S. Pat. No. 3,347,926 to J. D. Zech; 
U.S. Pat. No. 4,014,933 to Boettger et al.; U.S. Pat. No. 4,973,761 to 
Schoenleben & Mueller; and U.S. Pat. No. 5,003,107 to Zimmerman & Larkin. 
It is known in the art that compounds with primary and secondary amine 
functions can be used as reactive hardeners in epoxy resin formulations 
employed for protective coatings, electrical embodiments, adhesives, etc. 
Many of the known polyethyleneamines have been used for such applications. 
Grayson et al.,ed., Kirk-Othmer Encyclopedia of Chemical Technology, Third 
Edition, Vol. 7, p. 593. 
SUMMARY OF THE INVENTION 
The invention is a compound of the formula: 
##STR1## 
wherein R is a linear or branched alkyl group of from about 1 to 6 carbon 
atoms, R.sup.1, R.sup.2 and R.sup.3 are independently H or an alkyl group 
of from about 1 to 6 carbon atoms, and x+y is from about 2 to 80. 
Also disclosed is a compound of the formula: 
##STR2## 
wherein R is H or an alkyl group of from 1 to 16 carbon atom, R' is 
selected from the group consisting of hydrogen and lower alkyl radicals 
having about 1 to 8 carbon atoms and a +b=n where n is the number of moles 
of alkylene oxide used in the alkoxylation step and has the range of 2 to 
80. 
This invention is also a process for the preparation of a polyetheramine 
containing an imidazolidone (cyclic urea) group which comprises 
continuously passing ammonia, hydrogen and the corresponding polyol over a 
catalyst comprising nickel in combination with a transition metal promoter 
selected from the group consisting of copper, chromium, molybdenum, 
manganese, iron and zinc, or mixtures thereof. 
This invention is also an epoxy resin composition comprising a vicinal 
polyepoxide and a curing amount of the aminated alkoxylated derivative of 
the 1-alkyl-2-imidazolidone having the formula of FIG. 1. The resulting 
resin compositions produce materials having a degree of toughness and 
flexibility substantially improved over anything available in the art. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The sequence for preparing the novel imidazolidone containing 
polyetheramines (herein after referred to as IMD), starting with the 
substituted imidazolidone, is represented by the following: 
##STR3## 
wherein R' is a linear or branched alkyl group of from about 1 to 6 carbon 
atoms, R.sup.2 is H or an alkyl of about 1 to 16 carbon atoms, and R.sup.3 
is H or an alkyl group of from about 1 to 6 carbon atoms, and x+y is from 
about 2 to 80. 
The initiator, 1-alkyl-2-imidazolidone, can be easily prepared by reacting 
urea, dimethyl carbonate, ethylene carbonate or propylene carbonate with 
the corresponding 2-alkylaminoethylamine and is represented by the 
structure: 
##STR4## 
wherein R' is a linear or branched alkyl group of from about 1 to 6 carbon 
atoms. 
The preferred initiator is N-isopropyl-2-imidazolidone and is represented 
by the formula: 
##STR5## 
Also disclosed is a method for preparing the novel oxazolidinone containing 
polyetherdiamines, starting with the substituted oxazolidinone, and can be 
represented by the following: 
##STR6## 
wherein R is H or an alkyl group of from 1 to 16 carbon atom, R' is 
selected from the group consisting of hydrogen and lower alkyl radicals 
having about 1 to 8 carbon atoms and a+b=n where n is the number of moles 
of alkylene oxide used in the alkoxylation step and has the range of 2 to 
80. 
The initiator, hydroxyalkyl-2-oxazolidinone, can be easily prepared by 
reacting urea, dimethyl carbonate, ethylene carbonate or propylene 
carbonate with the corresponding 2-amino-2-alkyl-1,3-propandiol and is 
represented by the structure: 
##STR7## 
wherein R' is selected from the group comprised of hydrogen and lower 
alkyl radicals having from about 1 to 8 carbon atoms. 
The alkoxylation reaction employed to prepare the propylene oxide adduct of 
both the cyclic urea initiator and the oxazolidinone initiator utilized to 
prepare the compounds of this invention is carried out according to 
methods well-known in the art, as described in Examples 2,3,13,14,15 and 
Tables 1 and 8. 
The alkoxylation reactions proceed using alkylene oxides containing about 2 
to 16 carbon atoms, or combinations thereof. Particularly suitable are 
ethylene oxide, propylene oxide, 1,2-butylene oxide and 2,3-butylene oxide 
or combinations thereof. Especially preferred alkylene oxides include 
propylene oxide and mixtures of propylene oxide and ethylene oxide. It can 
be noted from Tables 1 and 8 that variations in the number of moles of 
alkylene oxides or mixtures thereof used in alkoxylation result in 
predictably different hydroxyl number products, expressed as mg KOH/g, for 
tile resulting polyols which seems to likewise result in variations in the 
properties observed in the elastomers produced using tile novel 
polyetheramines. 
The alkoxylated substituted IMD products and the alkoxylated substituted 
oxazolidinone-containing products can be converted to the corresponding 
primary amines by reaction with ammonia over a 
hydrogenation/dehydrogenation catalyst. Generally reductive amination 
catalysts are composed primarily of nickel, cobalt or copper, or these 
metals in combination as the active components. The catalyst can contain 
other metals as well, such as iron, zinc, chromium, manganese, zirconium, 
molybdenum, tungsten, rhenium, and ruthenium. Other promoters such as 
barium, magnesium, and phosphorous have been used as reductive amination 
catalysts. Precious metals such as platinum and palladium have also been 
used in some catalysts. The catalysts can be unsupported or supported. 
Common supports that have been used for these catalysts include alumina, 
silica, silica-alumina, zirconia, magnesia, and titania or mixtures 
thereof. 
In the examples of reductive amination described herein the catalysts used 
comprised nickel alone or in combination with copper, chromium, and 
molybdenum unsupported or supported on alumina. The quantity of nickel, 
copper, chromium, and molybdenum which are employed in the catalyst may 
vary. Good results for tile IMD products are observed where the catalysts 
comprises about 30 to 80 wt % nickel, 5 to 15 wt % copper and 0.1 to 2 wt 
% each of chromium and/or molybdenum as well as at least 50 wt % of the 
refractory metal oxide support. One preferred catalyst composition 
comprises about 30 to 50 wt % nickel, about 5 to 10 wt % copper, about 1 
to 2 wt % chromium, and about 0.1 to 1 wt % molybdenum and is deposited on 
an alumina support. Another preferred catalyst composition comprises about 
70 to 80 wt % nickel, about 10 to 15 wt % copper, and about 1 to 2 wt % 
chromium. Good results for the oxazolidinone products are observed where 
the catalyst consisted essentially of 30 to 80 wt % nickel, 2 to 20 wt % 
copper and 0. 1 to 2 wt % each of chromium and molybdenum as well as at 
least 50 wt % of the refractory metal oxide support. A preferred 
composition comprises 70 to 80 wt % nickel, 10 to 20 wt % copper, and 0.5 
to 1.5 wt % chromium. Another preferred composition comprises 35 to 40 wt 
% nickel, 4 to 8 wt % copper, 0.1 to 1.0 wt % molybdenum and is deposited 
on an alumina support. 
It was observed that no significant amount of product degradation occurred 
during the amination reactions. A number of other catalysts known in the 
art to be active in reductive amination, such as Raney nickel, would be 
expected to be active and selective, and therefore, useful in this 
reaction. 
The temperature for amination of the IMD polyol should be in the range of 
about 150.degree. C. to 350.degree. C. and is preferably from about 
200.degree. C. to 250.degree. C. The pressure for amination should be in 
the range from about 500 to 4000 psig and preferably from about 1500 to 
2500 psig. 
The temperature for the amination of tile oxazolidinone polyol can range 
from about 150.degree. C. to about 300.degree. C. and from about 500 to 
about 4000 psig. The preferred temperature range is from about 200.degree. 
to about 260.degree. C. The preferred pressure range is from about 1000 to 
about 3000 psig. 
Also disclosed is the use of compounds of the structure of FIG. 2 for 
making elastomers by reacting them with polyisocyantes using techniques 
known to those skilled in the art. 
A wide variety of aromatic or aliphatic polyisocyanates may be used. 
Typical aromatic polyisocyanates include p-phenylene diisocyanate, 
polymethylene polyphenylisocyanate, 2,6-toluene diisocyanate, dianisidine 
diisocyanate, bitolylene diisocyanate, naphthalene-1,4-diisocyanate, 
bis(4-isocyanatophenyl)methane bis(3-methyl-3-isocyantophenyl)methane, 
bis(3-methyl-4-isocyanatophenyl)methane and 4,4'-diphenylpropane 
diisocyanate. 
Other useful aromatic polyisocyanates are methylene-bridged polyphenyl 
polyisocyanate mixtures which have a functionality of from about 2 to 
about 4. See, for example, U.S. Pat. Nos. 2,683,730; 2,950,263; 3,012,008; 
3,344,162 and 3,362,979. 
In some applications a preferred polyaromatic polyisocyanate is methylene 
bis(4-phenylisocyanate) or MDI. Pure MDI, quasi-prepolymers of MDI, 
modified pure MDI, etc. Materials of this type may be used to prepare 
suitable RIM elastomers. Since pure MDI is a solid and, thus, often 
inconvenient to use, liquid products based on MDI are often used and are 
included in the scope of the terms MDI or methylene 
bis(4-phenylisocyanate) used herein. U.S. Pat. No. 3,394,164 is an example 
of a liquid MDI product. More generally uretonimine modified pure MDI is 
included also. This product is made by heating pure distilled MDI in the 
presence of a catalyst. The liquid product is a mixture of pure MDI and 
modified MDI: 
##STR8## 
Examples of a commercial material of this type are Dow's ISONATE.RTM. 125M 
(pure MDI) and ISONATE.RTM. 143L. Preferably, the amount of isocyanates 
used is the stoichiometric amount based on all the ingredients in the 
formulation. 
In the instant invention it has been discovered that the aminated 
alkoxylated N-alkyl-2-imidazolidone derivatives having the structure 
identified in FIG. 1 and that the aminated hydroxyalkyl-2-oxazolidinone 
derivatives having the structure identified in FIG. 2 have properties 
which make them particularly valuable as curing agents for epoxy resins. 
They can be used in epoxy resin compositions, such as films, castings, 
adhesives, etc., comprising a vicinal polyepoxide having an epoxide 
equivalency greater than about 1.8 and a curing amount of a curing agent 
such as the IMD amine or the oxazolidinone amine curing agents of this 
invention. 
The level of toughness and flexibility developed in systems using the 
polyetheramine-containing curing agents of this invention has previously 
been difficult to obtain. The significant improvements are believed to be 
due in part to the unique structure of these compounds. Systems cured with 
the subject polyetheramines are substantially improved over those systems 
prepared with similar curatives which do not contain these structures. 
The amines may be used as tile sole epoxy curative or blended with other 
known epoxy curatives to modify resin properties. These products may also 
be useful in epoxy, polyurea RIM and polyamide applications. 
The compounds of this invention may be used as the sole epoxy curative or 
blended with other known curatives, such as, for example, 
polyoxyalkyleneamines to modify resin properties. Such 
polyoxyalkyleneamine include, but are not limited to, the 
polyoxyalkylenediamines of the JEFFAMINE.RTM. D-series as exemplified by 
tile structural formula: 
##STR9## 
where x is a number from about 2 to 35 and includes, for example, 
JEFFAMINE.RTM. D-230, JEFFAMINE.RTM. D-400 and JEFFAMINE.RTM. D-2000. 
The compounds of this invention may also be used in combination with a 
polyoxyalkylenediamine of the EDR-series represented by the formula: 
EQU H.sub.2 N--CH.sub.2 CH.sub.2 (--O--CH.sub.2 CH.sub.2).sub.n --NH.sub.2 
where n=2 or 3, represented by JEFFAMINE.RTM. EDR-148 or EDR-192. 
Generally, the JEFFAMINE.RTM. polyoxyalkylenepolyamines employed in 
conjunction with the curing agents of this invention will have molecular 
weights of about 148 or more and, preferably will have molecular weights 
ranging from about 230 to 2000. All of the above JEFFAMINE.RTM. products 
are marketed by the Texaco Chemical Company, Houston, Tex. 
The IMD-containing and the oxazolidinone-containing polyetheramines can be 
combined, not only with polyoxyalkyleneamines such as those of the 
JEFFAMINE.RTM. series mentioned above, but with a variety of commercially 
available amines. Suitable examples are ethyleneamines, including, but not 
limited to diethylenetriamines, triethylenetetramine, etc., and aromatic 
or cycloaliphatic amines and catalytic amines such as imidazoles. 
Examples 6 to 11 compare properties of systems cured with the 
IMD-containing polyetheramine with properties of systems cured with 
JEFFAMINE.RTM. amines or blends of commercially available amines. The data 
confirms significant improvements in strength and flexibility. 
Examples 20 and 21 (infra) compare properties of systems cured with the 
oxazolidinone-containing polyetherdiamine with properties of systems cured 
with either JEFFAMINE.RTM. D-400 or a blend of JEFFAMINE.RTM. D-400 and 
JEFFAMINE.RTM. D-2000. 
In the instant invention, epoxy resin was cured at a temperature from about 
70.degree. C. to 90.degree. C. for about 1 to 3 hours and subsequently 
cured at a temperature of from about 115.degree. to 135.degree. C. for 
about 4 to 5 hours for the IMD-containing compounds. 
For the oxazolidinone-containing compounds curing of the epoxy resin can be 
carried out from about 60.degree. to 150.degree. C. for up to five hours 
and alternatively by curing at a temperature in the range of about 
70.degree. C. to 90.degree. C. for about 1 to 3 hours and subsequently at 
a temperature of from about 110.degree. C. to 130.degree. C. for an 
additional period of about 2 to 4 hours. 
The epoxy resins are preferably cured at a temperature above 70.degree. C. 
When the curing agent comprises a blend of the compounds of this invention 
and another polyoxyalkylenepolyamine, usually the polyetherdiamine will 
comprise from about 15 to about 100 wt % of the compound with the balance 
being the polyoxyalkylenepolyamine. 
Generally, the amine-cured vicinal polyepoxide-containing compositions are 
organic materials having an average of at least 1.8 reactive 1,2-epoxy 
groups per molecule. These polyepoxide materials can be monomeric or 
polymeric, saturated or unsaturated, aliphatic, cycloaliphatic, aromatic 
or heterocyclic, and may be substituted if desired with other substituents 
besides the epoxy groups, e.g., hydroxyl groups, ether radicals, aromatic 
halogen atoms and the like. 
These vicinal polyepoxide-containing compounds typically are of an epoxy 
equivalent weight (EEW) of 150 to 250. Preferably the base resin, which 
has an epoxy equivalent weight of from 175 to 195, is derived from 
condensing epichlorohydrin with 4,4'-isopropylidenediphenol or 
2,2-bis(p-hydroxyphenyl)propane to form 2,2-bis(p-2,3 epoxy 
propoxyphenyl)propane, a derivative of Bisphenol A. 
Preferred polyepoxides are those of glycidyl ethers prepared by epoxidizing 
the corresponding allyl ethers or reacting, by known procedures, a molar 
excess of epichlorohydrin and an aromatic polyhydroxy compound; i.e., 
isopropylidene bisphenol, novolak, resorcinol, etc. The epoxy derivatives 
of ethylene or isopropylidene bisphenols are especially preferred. 
A widely-used class of polyepoxides which are useful according to the 
instant invention includes the resinous epoxy polyethers obtained by 
reacting an epihalohydrin, such as epichlorohydrin, etc., with either a 
polyhydric phenol or a polyhydric alcohol. An illustrative, but by no 
means exhaustive, listing of suitable dihydric phenols includes 
4,4'-isopropylidene bisphenol, 2,4'-dihydroxydiphenylethylmethane, 
3,3'-dihydroxydiphenyldiethylmethane, 3,4'-diphenylmethylpropylmethane, 
etc. 
Among the polyhydric alcohols which can be coreacted with an epihalohydrin 
to provide these resinous epoxy polyethers are such compounds as ethylene 
glycol, propylene glycols, butylene glycols, pentane diols, 
bis(4-hydroxycyclohexyl)dimethylmethane, 1,4-dimethylolbenzene, glycerol, 
1,2,6-hexanetriol, trimethylolpropane, mannitol, sorbitol, erythritol, 
pentaerythritol, their dimers, trimers and higher polymers, e.g., 
polyethylene glycols, polypropylene glycols, triglycerol, 
dipentaerythritol and the like, polyallyl alcohol, polyhydric thioethers, 
etc. 
An epoxy resin which may be cured by the process of this invention is one 
prepared, for example, by the reaction of Bisphenol A with epichlorohydrin 
in the presence of sodium hydroxide. After condensation is complete, the 
crude resin is freed of residual epichlorohydrin, washed well to remove 
salt and soluble by-products and recovered. Among those which have been 
employed to demonstrate the effectiveness of the instant invention are 
diglycidyl ethers of Bisphenol A, such as liquid epoxy resin which has a 
molecular weight of approximately 380, a functionality of approximately 2, 
and an equivalent weight of approximately 185 to 192. 
Optionally, the epoxy resin formulations of the instant invention can 
include an "accelerator" to speed the amine cure of the epoxy resin, 
especially at ambient temperatures. In several applications, such 
acceleration is beneficial, especially when an epoxy resin is used as an 
adhesive in a flammable environment, thus making elevated temperature cure 
inconvenient or even hazardous. Lee, H. and Neville, K., HANDBOOK OF EPOXY 
RESINS, pp. 7-14, describes the use of certain amine-containing compounds 
as epoxy curing agent accelerators. 
Many accelerators are known in the art which can be utilized in accordance 
with the instant invention. Examples include salts of phenols, salicylic 
acids, amine salts of fatty acids, such as those disclosed in U.S. Pat. 
No. 2,681,901, and tertiary amines such as those disclosed in U.S. Pat. 
No. 2,839,480, incorporated herein by reference. 
It will further be realized that various conveniently employed additives 
can be admixed with the polyepoxide-containing composition of the instant 
invention prior to final cure. For example, in certain instances it may be 
desirable to add minor amounts of hardeners along with various other 
accelerators and curing agent systems well-known in the art. Additionally, 
conventional pigments, dyes, fillers, flame-retarding agents and the like 
which are compatible and natural or synthetic resins can be added. 
The preparation of a cured epoxy resin is carried out in the following 
manner: 
Epoxy resin is normally used without dilution and without other additives. 
A solvent may be used where components are very viscous. 
To a component containing the epoxy resin is added an equivalent amount of 
either the IMD-containing polyetheramine or the oxazolidinone-containing 
polyetheramine alone or in combination with a polyoxyalkylenediamine. The 
mixture is then mixed, degassed and poured into molds. These blends, where 
mixed with other amine curatives, should be present in the epoxy resin in 
an amount sufficient to provide about 0.8 to 1.2 amino (NH.sub.2) groups 
per oxirane group of the epoxy resin. 
In the various Examples the following terms are used to describe properties 
measured: 
HDT--(ASTM D648-72) Heat distortion temperature is the temperature at which 
a polymer sample distorts under load upon heating under specified 
conditions. HDTs can also be used to indicate the degree of cross-linking 
or extent of cure of an epoxy resin. 
Shore D hardness--(ASTM D-2240-81) Measured at 0 and at 10 seconds 
indentation hardness with durometer. 
Izod impact strength (ft-lb/in) (ASTM D256-81)--Izod impact testing is 
carried out with the pendulum-type device where the test specimen is 
positioned as a cantilever beam with the notched side facing the striker. 
Five samples are tested for impact with each formulation with the average 
being recorded as IZOD impact strength. 
Tensile Strength, psi (ASTM D638-80)--The rupture strength (stress/strain 
product at break) per unit area of material subjected to a specified 
dynamic load. "Ultimate tensile strength" is the force, at break, when a 
sample is pulled apart. 
Tensile Modulus, psi--Stress/strain 
Flexural Strength, psi (ASTM D790-80)--A measure of the ability of a 
material to withstand failure due to bending. 
##EQU1## 
The following Examples are merely illustrative and should not be construed 
as limitations on the scope of the claims.