CA1111192A - Epoxy additives - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The adhesion properties of amine-cured epoxy resins are unexpectedly enhanced by addition of certain polyether additives. The adhesively superior epoxy resin composition comprises a vicinal polyepoxide, a curing amount of an amine curing agent, and an effective amount of:
a polyether diureide having terminal ureido or and a molecular weight of from about 4000 to about 4500;
a polyether diamide having terminal amido groups and a molecular weight of from about 2000 to about 3000 and/or a polyether succinimide having terminal amino groups and a molecular weight of from about 4000 to about 4500.

Description

- D.75,117-FB
'' ' ~ Z

This invention relates to curable epoxy resins having increased adhesive strength; and, more particularly, to amine cured epoxy resins containing certain additives having poly-ether linkages. These additives include certain diureides, diamides, ureylenes and succinimide derivatives.
Epoxy resins constitute a broad class of polymeric materials having a wide range of physical characteristics.
The resins contain epoxide groups which are cured by reaction with certain catalysts or curing agents to provide cured epoxy resin compositions with certain desirable properties.
One such class of curing agents is generally the amines.
The most commonly used amine curing agents are aliphatic amines such as diethylenetriamine or triethylenetetramine, and/or polyoxyalkylene polyamines such as polyoxypropylene-diamines and triamines.
Epoxy resin composition-~ having improved physical properties are obtained by employing polyoxyalkyleneamines, and polyoxyalkylenediamines in particular, as curing agents.
It is common to employ, with such epoxy resin compositions, a co-curing agent such as those described in U.S. Patent No. 3,549,592.
Also known to be effective as epoxy curing agents or co-curing agents are various ureas and substituted ureas, such as those disclosed in U.S. Patents No. 3,294,749;

2,713,569; 3l386l956; 3,386,955; 2,855,372 and 3,639,338 The ureas disclosed in the above U.S. Patents are useful as either curing agents or as curing accelerators.
Aliphatic or aromatic compounds having a single termLnal ureido group are well known. It has been disclosed ~ , .. .. .. .. .

in U.S. Patent No. 2,145,242 that diureido terminated ali-- phatic compounds can be produced by reacting urea with an aliphatic diamine wherein each terminal amine has at least one labile hydrogen. Other substituted ureas are disclosed in U.S. Patent No. 3,965,072.
It is also known to use polyamides as epoxy curing agents. Simple amides such as acetamide, benzamide and adipamide have been used, but they have low activity and/
or solubility and require the use of basic catalysts. The advantages and disadvantages of polyamides as curing agents is discussed in Lee, Henry and Neville, K. Handbook_of EE~xy Resins, McGraw Hill Book Co., New York, 1967, but, genexally, ` the hydrogen atoms of the primary or secondary amides are .~ , .
weakly reactive with epoxy groups.
, I Moreover, it has been known to form oligomers from aliphatic or aromatic amines and dibasic acids or anhydrides (U.S. Patent No. 3,732,189). Diamines have also been reacted with maleimides or anhydrides to give elastomers (U.S. Patent No. 2,818,405). Also, thermosetting reslns have been prepared from epox1des and certain carboxyl termin-ated nitrogen containing compounds (see U.S. Patent No.

3,984,373).
It has now been unexpectedly found that specific polyoxyalkylene derivatives, terminated with amino, amido, ureido or ureylene groups, and having molecular weights of up to 4500, when employed a an epoxy additive/curing agent, provide cured epoxy resin compositions exhibiting outstand-ing strength of adhesion. Specifically, epoxy resins incorporating these additive/curing agents, upon curing, ,j ~ .
~ 30 preferably in the presence of an additional amine curing ,:
i - .
i -:. : : -;~; 3 -Z

.

agent, provide a material with high tensile shear strength, high resistance to peel, and superior adhesion to substrates.
The results of incorporating the additives according to the invention are particularly surprising in view of the fact that similar amine terminated compounds of lower mole-cular weight do not effect the same improvement in the cured resin. The cured epoxy resin compositions according to the invention are useful as coatings, castings, sealants and, especially, adhesives.
The present invention provides a curable epoxy resin composition which comprises:
(i) a.vicinal polyepoxide having an epoxide equiv-alent of greater than 1.8;
(ii) a curing amount of a polyamine curing agent .
having at least 3.reactive amino hydrogens; and, (iii) an effective amount of an additive of the formula R-NH-(fH-CH20)n~Z~(OCH2 fH) n (I) X X

in which R is hydrogen; a branched or straight chain alkyl, alkenyl or alkadienyl radical having up to 10 carbon atoms;
a monocyclic aryl, alkaryl or aralkyl radical having from 6 to lO.carbon atoms: an aminoethyl.or aminopropyl radical;
or a radical of the formula Rl-C0- or R'-NH-C0-in which R' is hydrogen; a b.ranched or straight chain alkyl, ~ .
alkenyl or alkadienyl xadical having up to 10 carbon atoms;
.or a monocyclic aryl, alkaryl or aralkyl radical having up : to 10 carbon atoms; . ~::
X is hydrogen, methyl or ethyl; ~

. -4- .. : -.
`

::

Y has the same meaning as R; or is a -Co-R3 radica'; a radical of the formula \ 3 , or a radical of the formula -Co-NH-R2-NH-co-R3 in which R2 i5 an alkylene, cycloalkylene, arylene, aralky-lene or alkarylene radical;
R3 is a radical of the formula -NH-(fH-C~20)n~Z~(OCH2 fH) n X ' X '-Z is an alkylene radical having 2 to 5 carbon atoms; and each n is from 15 to 25 i' .
In accordance with one embodiment of the invention, the additive is a diureide of the formula r ~
NH-C0-NH-(fH-CH20)n 2 (II) , , . X
. in which R' is hydrogen; a branched or straight chain alkyl, alkenyl or alkadienyl radical having up to 10 carbon atoms;
or a monocyclic.aryl, alkaryl or aralkyl radical having up .
' to 10 carbon atoms; . .
. X is hydrogen; methyl or ethyl; . ~
~ . 20 : :Z is an alkylene radical having 2 to 5 carbon atoms; and :
¢ ~ n is.rom 15 to 25. :-In accordance ~ith another embodiment of the inven-~ , tion, the additive is an amide of the for~ula _ :

~: ............. , ., : - :
, -, , .

~R' -CO-NH- (CH-CH20) n3 ~Z (III) in which R' is hydrogen; a branched or straight chain alkyl, alkenyl or alkadienyl radical having up to 10 carbon atoms;.
or a monocyclic aryl, alkaryl or aralkyl radical having up to 10 carbon atoms;
X is hydrogen, methyl or ethyl;
Z is an alkylene radical having 2 to 5 carbon atoms; and n is from 15 to 25.
In accordance with yet another embodiment of the 10invention, the additive is a ureylene of the formula ~R-NH- (CH-CH20-)n~Z~(OCH2 ~H) n ] 2 (IV
X , -in which R is hydrogen; a branched or straight chain alkyl, ; alkenyl, or alkadienyl radical having up to 10 carbon atoms;
a monocyclic aryl, alkaryl or aralkyl radical having from 6 to 10 carbon atoms; or an aminoethyl or aminopropyl radlcal;
X is hydrogen, methyl or ethyl;
Y' ls a -C0- radical or a radical of the formula in which R is an alkylene, cycloalkylene, arylene, aralky-lene or alkarylene radical; ~:

Z is an alkylene radical having 2 to S carbon atoms; and each n is from 15 to 25.
. --. In accordance with still a further embodiment of this inventlon the additive is a succinimide of the formula ~-NH-(7H-cH20)n-z (CH2 IH)n ~ 2 (V~
X X

-F- ~ ~ :
,, .

in which R is hydrogen; a branched or straight chain alkyl, alkenyl, or alkadienyl radical having up to lO carbon atoms;
a monocyclic aryl, alkaryl or aralkyl radical having from 6 to lO carbon atoms; or an aminoethyl or aminopropyl radical;
X is hydrogen, methy or ethyl; -Y is a radical of the formula Z is an alkylene radical having 2 to 5 carbon atoms; and n is from 15 to 25.
If desired, the composition in accordance with the invention can comprise an effective amount of a curing accelerator, e.g., a salt of a phenol, a salicycLic acid, an amine salt of a fatty acid, a tertiary amine, or a mixture of piperazine and an alkanolamine.
Preferably, the vicinal polyepoxide comprises at least 80% by welght o a polyglycidyl ether of a polyhydric phenol, and preferably, the polyamine curing agent is a polyoxyalky-lene polyamine having an amine equivalent weight of from 20 to 70, e.g., a polyoxyalkylene polyamine of the formula ~H2N (IHfH)m] Z or z- [(oclH2fH)mNH(cH2)pNH2]
X H (VI) H X (VII) ~ wherein X is hydrogen, methyl or ethyl; Z is a hydrocarbon '~ radical having 2 to 5 carbon atoms and having a value of from 2 to 4; m is a number from 1 to lS; r is a number from 2 to 4; and ~ is 2 or 3.
Generally, a composition in accordance with the present ' -~', , .

- , .
- :: ' . ' ': ' invention comprises:
- ti) lO0 parts by weight of the vicinal polyepoxidei (ii) an amount of the polyamine curing agent suffic-ient to provide from 0.8 to 1.2 equivalents of amino group per epoxy equivalent of the vicinal polyepoxide;
(iii) from 5 to 50 parts by weight of the additive;
and optionally, (iv) from l to 10 parts by weight of the accelerator.
The present invention also provides a cured epoxy resin composition obtained by curing a curable composition as defined above.
According to the present invention, blends of a poly-epoxide, an amine curing agent, the additive of formula (I) and, optionally, an accelerator are mixed and cured in accord-ance with conventional methods to provide cured epoxy resins havlng unexpectedly superior adhesive strength.
Generally the vicinal polyepoxide containing compos-itlons are organic materials having an average of at least 1.8 reactive 1,2-epoxy groups per molecule. These poly-epoxide materials can be monomeric or polymeric, sa~urated 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, and aromatic halogen atoms.
Preferred polyepoxides are those of glycldyl ethers prepared by epoxidizing the corresponding allyl ethers or reacting, by known procedures, a molar excess of epichloro- -hydrin and an aromatic polyhydroxy compound, i.e., iso-propylidene bisphenol, a novolakl or resorcinol. The epoxy ~ . - . .
; 30 derivatives of methylene or isopropylidene bisphenols are -~, " "

- . ~ . .
: . . : , : . . -. . :

, ,~

especially preferred.
A widely used class of polyepoxides which is useful according to the present invention includes the resinous epoxy polyethers obtained by reacting an epihalohydrin, such as epichlorohydrin, 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'-dihydroxydiphenylethyl-methane; 3,3'-dihydroxydiphenyldiethylmethane; 3,4'-dihydro~iphenylmethylpropylmethane; 2,3'-dihydroxydiphenyl-ethylphenylmethane; 4,4'-dihydroxydiphenylpropylphenyl-methane; 4,4'-dihydroxydiphenylbutylphenylmethane; 2,2'-dihydroxydiphenylditolylmethane; and 4,4'-dihydroxydiphenyl-tolylmethylmethane. Other polyhydric phenols which may also be co-reacted with an epihalohydrin to provide these epoxy polyethers are such compounds as resorcinol, hydroquinone, and substituted hydroquinones, e.g., methylhydroquinone.
Among the polyhydric alcohols which can be co-reacted with an epihalohydrin to provide these resinous epoxy polyethers are such compounds as ethylene glycol;
propy~ne glycols; butylene glycols; pentane diols; bis (4-hydroxycyclohexyl)dimethylmethane; 1,4-dimethylolbenzene;
glycerol; 1,2,6-hexanetrlol; trimethylolpropane; mannitol;
sorbitol; erythritol; pentaerythritol; and their dimers, ~ trimers and higher polymers, e.g., polyethylene glycolst ,~ ~ polypropylene glycols, triglycerol, and dipentaerythritol;
,:
polyallyl alcohol; polyhydric thioethers, such as 2,2',3,3'-tetrahydroxydipropylsulfide; mercapto alcohols such as monothioglycerol, or dithioglycerol; polyhydric alcohol partial esters, such as monostearin, or 9_ . : , pentaerythritol monoacetate; and halogenated polyhydric alcohols, such as the monochlorohydrins of glycerol, sorbitol, or pentaerythritol.
Another class of polymeric polyepoxides whi¢h can be amine cured and used in accordance with the present invention are epoxy novolak reslns obtained by reacting, preferably in the presence of a basic catalyst, e.g., sodium or potassium hydroxide, an epihalohydrin, such as epichloro-hydrin, with the ~esinous condensate of an aldehyde, e.g., formaldehyde, and either a monohydric phenol, e.g., phenol itself, or a polyhydric phenol. Further details concerning the nature and preparation of these epoxy novolak resins can be obtained in the previously mentioned Handbook ~ e~y Resins, by Lee and Neville.
~ It will be appreciated by those skilled in the art that the polyepoxide compositions which are useful according to the practice of the present invention are notlllmited to those containing the above described polyepoxides, but that these polyepoxides are to be considered merely as being representative of the class of polyepoxides as a whole.
The amine curing agents which can be utilized in accordance with the present invention are generally any of those amine curing agents which are well known to be useful for the curing of vicinal epoxides. GeneralIy, those curing agents having at least three reactive amino hydrogen atoms are useful.
Exemplary of such amines are alkylene polyamines such as diethylene triamine, and triethylene tetramine; oxy-alXylene polyamines such as polyoxypropylene diamine and triamine; and diamino derivatives of ethylene glycol, such .

.
.~ .

.Z

as 1,13-diamino-4,7,10-trioxatridecane.
Additionally, aromatic amine curing agents are useful, such as the alkylene-linked polyphenyl amines, phenylene diamines and polycyclic or fused aromatic primary amine com-pounds. Additionally the corresponding cycloaliphatic com-pounds can be used.
Likewise, the polyamide curing agents, such as the condensation products of polyamines and polycarboxylic acids are useful. Suitable such amide compounds are, for example, the condensation product of a polyamine and a dimerized fatty acid produced in accordance with U.S. Patent No. 2,379,413.
Of the amine curing agents known to be effective in curing a vicinal epoxy resin, preferred curing agents in ;~
accordance wIth the present invention are the polyoxyalkylene containing amine compounds. A preferred class of polyoxy-.~ .
i~ alkylene polyamines is depicted by the formula:
[H2N-tlHIHO)~ Z tVI) 'l wherein X, Z, m and r have the meanings gi~en above.
The most preferred polyoxyalkylene polyamines are the polyoxypropyl diamines wherein X is methyl, n is 1 to 10, Z
¦ ls 1,2-propylene radical and r is 2. These polyoxyalkylene .
polyamines can be prepared by known methods, as disclosed .1 .
in U.S. Patent No. 3,236,895 and 3,654,370. The most pre-ferred polyoxyalkylene polyamine is a polyoxypropylene ! ~ ~ diamine ha~inq a molecular weight of about 230.
Another preferred class of polyoxyalkylene polyamines can be depicted by the formula:
~ Z Eolc~ lcH)m~H(cH2)pNH2] t~II) 1~ " , ~' ' . ' . ,. . :

wherein X, Z, m and r are defined as above, and ~ is 2 or 3.
These poly(aminoalkylamino)polyethers are the hydrogenated product of the cyanoalkylated adduct of a polyoxyalkylene polyamine as above described. The preparation of the cyano-alkylated adducts is described in U.S. Patent No. 3,666,788.
Preferred such compounds are the hydrogenated cyano-ethylated polyoxypropylene triamines.
The polyether diureide additives of formula (II) can generally be described as polyoxyalkylene containing materials having terminal ureido or mono-substituted ureido groups and a molecular weight of from 2000 to 3000. More specifically, these compounds are polyoxyalkylene compounds having terminal ureido groups, of the formula:

[R'-NH-C0-NH-(C~H CH20)n]2 (II) wherein R' is hydrogen; a branched or straight chain alkyl radical having from 1 to 10, preferably from 1 to ~, carbon atoms; a monocyclic aryl, alkaryl or aralkyl radical having from 6 to 12, and more preferably 6 to 8, carbon atoms; or, are branched or straight chain alkenyl or alkadienyl radical of from 2 to 10, preferably 3 to 8 carbon atoms; X is hydro-gen, methyl or ethyl; Z is alkylene having 2 to 5 carbon . , atoms and n is a number from 15 to 25 selected such that , the molecule o the above formula has a molecular weight 1- of from 2000 to 3000. T~e preferred diureides are of the above formula wherein R' is hydrogen or alkyl, and more preferably alkyl of from 1 to 4 carbon atoms î X is methyl;
Z is 1,2-propylene; and n is from 16 to 19. Preferred alkyl groups are met~yl, ethyl, n-propyl and n-butyi.

, .
~ -12-- . : :- - . , - :: - .- . - . - : - :

The polyether diureide compounds are formed by the reaction of a ureido or mono-substituted ureido forming compound with a polyoxyalkylene diamine having a molecular weight value such that the ureido containing product has a molecular weight of from 2000 to 3000, generally at tempera-tures in the range from 25 to 150C, and in a molar ratio of about 2 moles of ureido or mono-substituted ureido form-ing compound for each mole of diamine.
The diamines that are useful in forming the additives are polyoxyalkylene diamines of the formula:

[H2N (IH-cH2-o)n] -Z (VIII) X ' '~
wherein X, Z and n have the meanings given above. These polyoxyalkylene polyamines can be prepared by known methods as disclosed in U.S. Patents No. 3,236,895 and 3,654,370.
It will be understood that the stated values of n are aver-ages, not integers.
The ureido forming compounds are generally those which supply the 0=C-NH2 radical. Urea is preferred. When urea is employed as a reactant, the reaction proceeds with the evolution of ammonia, and the terminal primary amino groups o the polyoxyalkylenepolyamine are converted directly into ureido groups.
While urea is the preferred ureido forming compound, other ureido forming compounds can be utilized. S~nce the polyoxyalkylenepolyamine reactant already contains t~erminal primary amino groups, isocyanates of the general formula M NC0 , wherein M+ is generally an alkali metal, such as 6~ .
potassium, or sodium, can be used. The preferred isocyanates . ,, ..
' are sodium and potassium isocyanate, primarily because of their availability.
The mono-substituted ureido forming compounds are generally isocyanates of the formula R-N=C=0 wherein R has the character of either an aliphatic or aromatic monovalent hydrocarbon radical as defined herein above.
In accordance with this method, the reactants are simply mixed in correct molar ratios in a suitable reaction vessel and heated, if necessary, until the reaction occurs.
The functionality of the polyoxyalkylenepolyamine is dependent upon the number of terminal primary amino groups, which in the present case is 2. It will be realized that each mole of ureido forming compound, or substituted ureido forming compound, will react with a single termlnal primary amino group of the polyoxyalkylenepolyamine. It is particularly important that, in forming the additives employed according to the present invèntion, a specific molar ratio of reactants be maintained. Specifically, about 1 mole of ureido orming compound for each amino group of the polyoxyalkylenepolyamine is requlred. Thus, with the diamine, about 2 moles of ureido forming compound ls util-ized. Preferably the reac~ion i8 carried out in the presence of a slight excess of ureido forming compound to ensure complete conversion of the amino groups.
The polyether diamide additive of general formula (III) can generally be described as polyoxyalkylene contain-ing materials having terminal amido groups and a molecular weight or from 2000 to 30G0. More specifically, these com-pounds are polyoxyalkylene compounds having terminal amido - groups, of the formula:

~ ' :
-14~

: ~ . . , - - -' , '' ~. .' . . ' . . ' ~ ,.~ '. ' ' ' X (III) wherein R', X, Z and n have the general and preferred meaning given in connection with formula (II) above.
The polyether diamine compounds are formed by the reaction of an amido forming compound with a polyoxyalkylene diamine having a molecular weight of from 2000 to 3000 at temperatures in the range from about room temperature to 200C in a molar ratio of about 2 moles of amido forming ; `
compound for each mole of diamine. There are many known methods for forming such compounds by acylation of the amine reactant.
The diamines that are useful in forming the additives are those of formula (VIII) above.
The amide forming compounds are generally those which supply the acyl (R'C0) radical, wherein R' is defined as above. Suitable such compounds include the monocarboxylic acids, and corresponding acid chlorides and esters.
Acyllatlon reactions that can be utilized are well known and will not be fur~her herein discussed.
In accordance with these known methods, the reactants are simply mlxed in correct molar ratios in a suitable reaction vessel and heated until the reaction occurs.
Curable epoxy resin compositions containing the ureylene and succinimide additives of formulae (III) and (IV) are most conveniently prepared by a different technique in three steps. Firstly, the polyether ureylene or polyether succinimide having terminal primary amino groups is prepared by charging a suitable reaction vessel with approxlmately 2.0 mols of a polyoxypropylenepolyamine having a molecular ~: ' , -weight of about 2000 and consisting substantially of the polyoxypropylenediamine; and about 1.0 mole of urea or maleic anhydride.- When urea is used, the mixture is then heated gradually to a temperature of 180 to 200C and main-tained until the evolution of ammonia has ceased. The resultant reaction mixture is then stripped at a temperature of 120 C to 150 C and a pressure of 1 mm Hg to form a vis-cous liquid.
When the polyether succinimide is being prepared, the mixture is heated to reflux at a temperature of 140 to 170C, until azeotropic water removal has ceased. The resultant reaction mixture is then stripped at a temperature of 170C
to 190C and a pressure of 3 mm ~g to form a viscous liquid.
One surprising aspect of the resultant product is the suc-cinimide structure.
In the second step, the viscous liquid obtained in step 1 and containing the polyether ureylene or the polyether succinimide is mixed wlth a polyoxypxopylenediamine having a molecular weight of from 200 to 250 in a ratio of from 5:1 to 1:5 by weight. A commercial accelerator can be added if desired.
In a third step, the mi~ture obtained in step 2 is added to a suitable amount of the vicinal polyepoxide, e.g., a diglycidyl ether of 4,4'-isopropylidene bisphenol, such ' that the total number of equivalent amino groups is about equal to the number of equivalents of epoxide in the epoxy resin composition. The epoxy resin and the curing mixture are thoroughly admixed with the addi~ion of about three drops o~ a silicone fluid to prevent the formation of voids and bubbles. The resulting formulation, after degassing ' .

,, ,,, , . . ~ :
- , . . .. - , . . . . .
, . , . . , ~

under vacuum for 2 to 5 minutes, is applied to substrates to be bonded and/or cast into moulds. The resins are cured at room temperature, and preferably post cured at a tempera-ture from 80C to 125C. The cured products exhibit improved tensile shear strength; flexural strength; ultimate elongation; and, especially superior adhesion to substrates.
The amine terminated polyether containing ureylene additive/curing agent can generally be described as poly-oxyalkylene containing materials having a single ureylene linkage, terminal amino groups, and a molecular weight of from 4000 to 4500. More specifically, these compounds are amino terminated polyoxyalkylene compounds having a u,reylene linking group and are of the formula:

rRNH tCH~CH2~)n~Z~tO~CH2 fH) n ~2 (IV) X ' X

' wherein R, X, Y', Z and n have the meanings given above.
The material has a molecular weight of from 4000 to 4500.
The preferred amine termina~ed ureylenes are of the above formula (IV) whereln Y' is a carbonyl radical, R ls hydrogen or alkyl, preferably alkyl of from 1 to 4 carbon atoms; or 2-aminopropyl; X ls methyl; Z is 1,2-propylene;
and n is an average number from 16 to 19. Preferred alkyl groups include methyl, ethyl, n-propyl and n-butyl. In accordance with the most preferred embodiment R is hydrogen.
The primary amino terminated polyether ureylene compounds are formed by the reaction of a ureylene forming compound with a polyoxyalkylene diamine having a molecular weight of from 1800 to 2200 at temperatures in the range from 100C to 200C in a molar ratio of 1 mole of ureylene forming compound for 2 moles of diamine.

.: . . .. : . . .

The diamines that are useful in forming the additives are the polyoxyalkylene diamines of formula (VI) above.
These polyether ureylenes can be formed by the reac-tion of a polyoxyalkylenepolyamine, wherein the alkylene contains from 2 to 4 carbon atoms, with urea, a ureylene forming compound, or an organic bifunctional isocyanate. `
Urea is preferred.
Whenever urea is employed as the reactant, the reac-tion proceeds with the evolution of ammonia and the terminal primary amino groups of the polyoxyalkylenepolyamine is converted into a ureido group. The functionality of the polyoxyalkylenepolyamine is dependent upon the number of terminal primary amino groups. Since urea itself is bi-functional, each molecule of urea can react with two terminal amino groups of the polyoxyalkylenepolyamine.
While urea is the preferred xeactant, other urea forming compounds may be utilized within the scope of the invention to supply the linking carbonyl radical. Since the polyoxyalkylenepolyamine reactant already contains terminal prlmary amino groups, compounds such as carbonyl dilmldazole, phosgene, and diphenyl carbonate may be used to supply the carbonyl radlcal to form ureylene linkages without the llberation of ammonia. `
Another class of polyether ureylenes which is useful ln the practlce of this invention, is formed by reaction of polyoxyalkylenepolyamines with a bifunctional organic isocyanate. This isocyanate can be for example an aromatic, aliphatic, or mixed aromatic/aliphatic diisocyanate of the formula R2(NC0)2, where R2 has the meaning given above. The isocyanate can be obtained, for instance, from the , phosgenated condensation product of aniline and formaldehyde.
One suitable compound is 4,4'-diphenylmethanediisocyanate, or the isomers thereof, such as 2,4'-diphenylmethanediiso-cyanate. Mixtures of the isomers can also be used.
According to another embodiment, secondary amino terminated polyether ureylene compounds are utilized.
Preferably, these compounds are formed by reductive amin-ation of the primary amino terminated compounds prepared as above herein described.
The reductive amination of primary amines with alde-hydes and ketones over standard hydrogenation/dehydrogenation catalysts is well known and will not therefore be ~urther discussed herein. Another well known method for production of the secondary amLno containing compound involves the use of an organo halide. This method is not preferred, because of interfering side reactions.
According to a further embodiment, an aminoalkyl amine terminated polyether ureylene compound is formed by cyano-alkylation of the primary amine terminated polyether ureylene compound above described and subsequent hydrogen-ation of the cyanoalkylated product. Preparation of the cyanoalkylated adducts is descrLbed in U.S. Patent No.
3,666,788. The cyanoalkylated products are then hydrogenated in a conventional method, e.g., over a well known hydrogen-.
ation/dehydrogenation catalyst.
The amine terminated polyether containing succinimide additive/curing agent can generally be described as polyoxy-alkylene containing material having at least one succinimide linkage, terminal amino groups, and a molecular weight of from 4000 to 4500. More specifically, these compounds are , .

amino terminated polyoxyalkylene compounds having at least one succinimide linking group and are of the formula:

~RNH(fH-cH2-o)n-z-lo-c~2 IH)m~2 ( ) X X
wherein X, y2~ z and n have the meanings given above.
The preferred amine terminated succinimides are of the above formula (V) wherein R is hydrogen or alkyl, preferably alkyl of from 1 to 4 carbon atoms; or 2-amino-propyl; X is methyl; Z is a 1,2-propylene; and n is a number from 16 to 19. Preferred alkyl groups include methyl, ethyl, n-propyl and n-butyl. Most preferably, R is hydrogen.
' The primary amino terminated polyether succinimide compounds are formed by the reaction of maleic anhydride with a polyoxyalkylene diamine having a molecular weight of from 1800 to 2~00 in two steps. First, the reactants are mixed at lower temperatures, i.e., room temperature and the crude reaction product is then heated, with the removal of water, with one mole of maleic anhydride at a tempexature of from 120C to 180C.
The diamines that axe useful in forming the additives are the polyoxyalkylene diamines of formula (VI) above.
The reaction of the polyoxyalkylenepolyamine, with màleic anhydride, proceeds with the liberation of water and one terminal primary amino group of the polyoxyalkylene-polyamine is converted into a succinimide group. The maleic anhydride~acts bifunctionally, linking by way of the ~
ethylenic unsaturation to the terminal prior amino group --o another polyoxyalkylenediamine. -According to another embodiment, secondary amino ' . .

, ~ . 1 , ca2 terminated polyether succinimide compounds are utilized.
Preferably, these compounds are formed by reductive amination or cyanoalkylation and reduction of the primary amino ter-minated compounds as previously described.
It will be realized that, in accordance with the instant invention, the primary amino terminated ureylene or succinimide can function as the sole amine curing agent.
Thus, these compounds function both as an additive to effect adhesion and an amine curing agent.
While it is generally possible to employ the primary amino terminated ureylene succinimide compounds as the sole curing agent in the epoxy resin composition, it is preferred to employ these materials in combination with one or more conventional amine curing agents.
Optionally, the epoxy resin formulations of the instant invention can include an "acceleratorl' to speed the amine cure o the epoxy resin, especially at ambient tempera-tures. In several applications, such acceleration is bene-ficial, especially when an epoxy resln is used as an adhesive ZO in flammable environment, thus making elevated temperature cure inconvenient or even hazardous. Lee and Nevil~3,in Handbook of Epo~xy Resins, pp. 7-14, describe the use of certain amine-containin~ compounds as epoxy curing agent-accelerators.
Many accelerators are known in the art which can be utilized in accordance with the instant in~ention. Examples include sa~ts of phenols; salicyclic acids; amine salts of fatty acids such as those disclosed in U.S. Patent No.
2,681,901; and, tertiary amines such as those disclosed in - U.S. Patent No. 2,839,480. A preferred accelerator is `
-21- ~

: ,,, , -- , ~ :

disclosed in U.S. Patent No. 3,875,072 and comprises a com-bination of piperazine and an alkanol amine in a weight ratio of 1:8 to 1:1.
According to the instant invention, the adhesive properties of prior art amine-cured epoxy resins having an epoxy equivalency of greater than 1.8 are enhanced by the addition of an effective amount of the additive as herein-before described. The amount of additive effective in bringing about the increased adhesive property is somewhat empirical and will depend upon the resin, whether an additional amine curing agent is used, and whether an accelerator is used. Generally, the prlmary amino terminated compound, when used as a curing agent/additive can be util-ized in approximately stoichiometric amounts.
When utilized with other known amine curing agents, the additives are preferably utilized in amounts from 5 to 40 parts by weight, based on 100 parts by weight of the resin, when the additives of formulae ~IV) and (V) are employed, and in amounts from 5 to 50 parts by weight, per 100 parts by weight of resin, when additives of formulae ~II) and (III) are employed.
Whether used alone or with an amine curing agent, the exact amount of additive materlal needed to increase adhesion can readily be determined without undue experimentation, owing to the fact that a resin mixture containing an effective ; amount of the additive will undergo chànges which are readily vislble as curing proce~ds. Specifically, the curing resin takes on an opaque, milky white appearance that becomes more , pronounced during curing and results in a product which has a lustrous white appearance. It will be realized that, " ' - : ~ .
-22- ;

: :. .. . . ... . . .

advantageously, this optical absorption shift enhances the beauty of cast objects and makes it unnecessary to use white pigments or fillers.
The ratio of the additive and the curing agent to resin can be easily determined on an equivalence basis. This equivalence determination should also include the functional groups of the accelerator, if one is used. The amount is calculated by adding ~ogether the number of equivalents, on the basis of weight per replaceable N-H group, in the sum of the amine curing agent, the amine terminated additive and the accelerator, if one is used. Preferably, based on the above calculations, wherein a mixture of a polyoxyalkylene-diamine curing agent, the primary amine containing additive and the preferred accelerator are utilized, the mixture is used in amounts which provide up to a 10% excess of the stoichiometric amount required, based on the resin.
According to a preferred embodiment, the adhesive properties of prior art xesin formulations having an epoxy equivalency greater than 1.8 are enhanced by addition of an effective amount of the additive according to the invention.
The most preferred additives are those in which 2 moles of a polyoxypropylenediamine having a molecular weight of 2000 are condensed with:
a) 2 moles of urea to form a preferred diureide;
b) 2 moles of formic acid to form a preferred diamide; - -~
c) 1 mole of urea to foxm a pxeferred ureylene; and d) 1 mole of maleic anhydride to form a preferred succinimide.
~referred prior art resin formulations comprise polyglycidyl ethers of polyhydric phenols, cured by incorporating therein ' , . . .
~ . . , -- : . . . . . .

-a curing amount of a polyoxyalkylenepolyamine of molecular weight from 200 to 500 and an accelerator combination of piperazine and an alkanolamine, in a weight ratio of 1:8 to 1:1. Exemplary preferred prior art compositions can be enhanced in accordance with the instant invention and are disclosed in U.S. Patent No. 3,943,104.
The curable epoxy resin compositions of the instant invention generally comprise a vicinal polyepoxide, having an epoxy equivalency greater than 1.8, a curing amount of an amine curing agent, an effectlve amount of the amine terminated polyether succinimide additive; and, optionally, an accelerator.
Although all of the epoxy resins disclosed herein are generally useful in accordance with the invention, those ~ased on aliphatic compounds are preferably not used exclus-~,~ lvely~ The presence of resins containing polyglycidyl ethers of polyhydric phenols in amounts greater than 50% by weight of the resin constituent, and more preferably 80% by weight, and most preferably 100% by weight, has been shown great~y to enhance the desirable properties of the cured material, especially the adhesive strength.
Likewise, althou~h all of the disclosed amine curing ; agents are generally useful to cure the resin, it has been ~ound that those resins containing curing agents, (other than the additive) wherein the amino moieties are separated by large aliphatic or oxyalkylene chains, are viscous and rather difficult to work with. For example, rqsins cured -~
with a polyoxypropylenediamine having molecular weights much in excess of 400, are not practically utilized to enhance adhesive~strengths in the presence of otherwise effective ~" l ::
. . :. . :.-: .

amounts of the additives. As a matter of handling and con-venience, those amines of molecular weight below 500 are preferred. The more preferred amine curing agents are those polyamines having an amine equivalent weight of from 20 to 150, more preerably from 40 to 70. Examples of such agents include polyoxypropylenediamines having a molecular weight in the range of 200 to 500, and polyoxypropylenepolyamines having a molecular weight of from 400 to 700.
It will be realized that any amine curing agent which is less effective in providing the adhesively superior resins can readily be avoided by the skilled artisan without undue experimentation, since such agents do not effectuate the "optical shift".
The amine-cured resins having superior adhesion in accordance with the instant invention are prepared in a conventional manner. When an amine curing agent is employed ; in addition to the additive, the mixture is combined with the polyepoxide composition in amounts accordlng to the amlne ;
equivalent weight of the admixture. Generally the nu~ber of equivalents of amine~groups is from 0.8 to 1.2 times the number of epoxide equivalents present ln the curable epoxy resin composltion, with a stoichiometric amount being pre- `
ferred. When using an accelerator, amounts from 1 to 10 parts by weight based on 100 parts by weight of the resin are generally satisfactory. The exact amount of constituents in accordance with the above general requirements will depend primarily on the appllcation for which the cured resin is -intended.
When the additive is used alone, it is incorporated into the uncured resin b~ simple mixing. When an additional -, `
.

z curing agent is used, preferably, the additive is first mixed -with the curing agent and/or the accelerator before addition to the resin. The constituents forming the curable material are then intimately mixed by standard methods, and degassed in the presence of a commercial defoamer and minute amounts o~ silicone oils to prevent voids and bubbles.
When an accelerator is used, a preferred accelerator comprises from 1 to 5 parts by weight, per one hundred parts by weight of the resin, of a piperazine!alkanolamine admix-ture in a weight ratio of from 1:8 to 1:1, piperazine to alkanolamine. The above amount of accelerator is mixed with a polyoxyalkylenediamine curing agent in amounts o~ from 10 to 50 parts by weight accelerator to 100 parts by weight of the curing agent.
As mentioned hereinbefore, while it is satisfactoryto employ the additive as the sole curing agent in the epoxy resin composition, it is preferred that it be employed in combination with an amine curing agent conventionally employed in curlng epoxy resin composltions, as previously herein enumerated. Polyoxyalkylenediamines of the type hereinbefore described and having an amine equivalence of from 40 to 70 are preferable (co)-curing agents. It has been found that ratios of additive to amine (co)-curing agent of from 5:1 -to 1:5 produce cured epoxy resin compositions with signif-icantly improved properties, for example, tensile shear strength, flexural strength, ultimate elongation and, most significantly, adhesion. -~
Generally, the mixture of epoxy resin, polyoxyalky-j lenepropylene polyamine, the additive and the accelerator combination of piperazine and alkanolamine is allowed to - ~ --seLf-cure at am~ient temperatures of 0 to 45C. It has been found expeditious that the mixture be post-cured at elevated temperatures of up to 135C.
In accordance with a preferred embodiment r a curable resin comprises a diglycidyl ether of 4,4'-isopropylidene bisphenol; a curing amount of a polyoxypropylene diamine having a molecular weight of from 200 to 250 as curing agent, piperazine and a triethanolamine in a weight ratio of 3 to 7 as accelerator; and, an effective amount of the additive.
According to a greatly preferred embodiment, resins of the polyglycidyl ether of polyhydric phenol type are cured by incorporating therein up to about a stoichiometric amount of a polyoxyalkylenepolyamine having a molecular weight of about 230; from 5 to 30 parts by weight of the ~
additive; and from 1 to 5 weight percent, based on 100 parts ~;
by weight of the resin, of an accelerator comprising a mixture of piperazine:triethanolamine in a 3:7 weight ratio.
The composition is cured at room temperature, (about 25C~, 1, . .
to produce products having superior adhesive strength in accordance wlth the instant invention~
It will further be realized that various conveniently employed additives can be mixed with the composition of the 1 ' ' ~ ' ', , invention before final cure. For example, in certain instances it may be desired to add minor amounts of other 1~ .
,,, polyalkyleneamine co-catalysts as herein described, or hardeners, along with various other accelerators and curing agent systems weLl known in the art.
Additionally,~compartible conventional additives, ; such a9 pLgments;~dyes; flllers;~flame retarding agents;
30 ;~ and~natural or synthetlc resins can be added. Furthermore, although not preferred, known solvents for polyepoxide materials such as toluene, benzene, xylene, dioxane, and ethylene glycol monomethylether can be used. The poly-epoxide resin compositions according to the present inven-tion can be used in any of the above applications for which polyepoxides are customarily used. One outstanding feature of the instant composition resides in the fact that they are opaque upon curing and give a smooth, white lustrous surface which may be of particular benefit for certain lC moulding and casting operations. The compositions of the invention can be used as impregnants, surface coatings, pottings, capsulating compositions, laminants, and, particularly and most importantly, as adhesives for bonding metallic elements or structures permanently together.
The following examples illustrate the nature of the ~ :
instant invention but are not intended to be limitative thereof.

In this Example, a polyether diureido terminated additive was prepared. Into a suitable reaction vessel, equipped with stirring apparatus, were added 1980 grams (1 mole) of a polyoxypropylenepolyamine having a molecular weight of approximately 2000, and an analysis of 1.01 milliequivalents (meq.) primary amine/g sold under the tradename "JEFFAMINE~ D-2000" by Jefferson Chemical Co., Austin, Texas 78751 and 180 grams of urea (3.0 moles).
The mixture was flushed with nitrogen and stirred under nitrogen for 2 hours at 130 to 134C. A second portion of 990 grams (0.5 moles of "JEFFAMINE~ D-2000l' was added over a 3 hour period at a temperature of 132C. The reaction mixture was maintained at 134C for another 70 minutes, during which time it was vigorously stirred to wash sub-limate from the upper surface of the reaction vessel. The crude reaction product was then stripped at 130C/1.4 mm Hg to produce a viscous residue which upon analysis showed 2.54% N, 0.01 meq. total amine/g.

In this Example a bis(N-substituted ureido) termin-ated material was prepared. According generally to the procedure of Example 1, 891 g of "JEFFAM~NE~ ~-2000" was placed in the apparatus described in Example 1. In a nitro-gen atmosphere over a period of 45 minutes, 109 g of phenylisocyanate were added to the stirred polyoxypropylene-diamine at a temperature of about 55C. The temperature was raised to 60C and the mixture was stirred an additional two hours. The corresponding bis(N-phenylureido) terminated compound was recovered and upon analysis showed 2.2% N, 0.009 me~. total amine/g.
To il:lustrate the advantage of the polyether ureide additives of this invention, various epoxy formulations, employing the diglycidyl ether of 4,4'-isopropylidene bis-phenol, were cured with various known polyamine curing agents. Where indicated, a commercial accelerator was util-ized. Three drops of silicone fluid were added to each formulation to prevent formation of voids and bubbles.
After degassing under vacuum, the formulations were cured under the conditions indicated. In appropriate examples, the cured products were subjected to standard American Society for Testing Materials (ASTM) tests for Izod impact strength (ASTM designation D-256), flexural strength and .~ ' , .
, ~ -29- ~ -B ` ~

~ . . . ... ~ . - .. . . . .... ....... . ~ .. .

~Z

modulus of elasticity in flexure (ASTM designation D-790-66), tensile strength and elongation at break (ASTM designation D-638-64 T), deflection temperature (ASTM designa~ion D-648-56) and hardness (ASTM designation 2240-64 T) and/or hardness Shore D, and peel strength (ASTM D-903). The tensile shear strength (ASTM D-1002-64) was measured on adhesive bonds.
All substrates were aluminium panels (No. 2024-T-3 alloy, 16 gauge), degreased, then chromic acid etched prior to bonding. The abbreviations in the Tables, pbw, psi and g.
stand for parts by weight, pounds per square inch and grams, respectively.
EXAMPLES 3 to 8 In these Examples, epoxy resins were prepared wherein diglycidyl ether of 4,4'-isopropylidene bisphenol was cured with a polyoxypropylenediamine curing agent of m.w. 230 having an equivalent weight of 58 to which were added the indicated amounts of the diureide prepared in Example 1.
The resulting resins were used to bond aluminium to aluminium and the resultant composite was subjected to the ASTM tests herein descrlbed~ The data, which are for comparative pur-poses oniy, are presented in the following Table I.

3.:~Z

TABLE_I

Exam~les Formulation 3 4 5 _ l 8 ~ -Epoxide, pbw (Eq. 190) 100 100 100100 100 100 Curing agent, pbwl) 30 30 30 30 30 30 Accelerator, pbw2) 10 10 10 10 10 10 ' Diureide pbw3) 0 5 10 20 25 30 Tensile shear, pSi4 ) 1250 3200 32003300 3650 3600 1) Sold by Jefferson Chemical Co., Austin, Texas 78751, under the name "JEFFAMINE~ D-230".
2) A piperazine-triethanolamine admixture (30:70) sold by Jefferson Chemical Co., Austin, Texas 78751, under the name "Accelerator 398".
3) The product of Example 1.
4) Cure: 7 days, room temp.

This Table demonstrates the improved adhesion strength of the epoxy formulation when amounts of the bis-ureide are added to an epoxy formulation cured with a polyoxypropylene-diamine of m.w. 230.
EXAMPLES 9 to 14 In comparisons substantially identical to those of Examples 3 to 8, the bis(phenyl substituted) ureide prepared in Example 2 was used as the additive. The results are ;
presented in Table II. ;~
:: .
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-~

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..
: . . ... - . ... ... .. - ~ -. . ... . . . .... . .. . . . . . .
- . . . ..

`` ` ~ 2 TABLE II
Examples Formulation 9 10 11 12 13 14 Epoxide, pbw (Eq. 190) 100 100 100 100 100 100 Curing agent, pbw1) 30 30 30 30 30 30 Accelerator, pbw2) 10 10 10 10 10 10 ..
Diureide pbw3) 5 10 20 30 40 Tensile shear, psi4) 1500 1700 34003300 2800 2900 1) "JEFFAMINE~ D-230"
2) "Accelerator 398" :~.
3) The product of Example 2 4) Cure: 7 days, room temp.

EXAMPLES 15 to 19 , ., j In order to demonstrate the surprising adhesive pro-perties of resins containing the additives of the present invention, a low molecular weight polyoxypropylene diureide was prepared and added to resins on the same equivalent basis as those of Examples 3 to 14.
First, a diureide having molecular weight of about 400 was prepared as in Example 1, but using a polyoxypropyl-diamine of m.w. 400 sold under the tradename "JEFFAMINE~ D- .
400". The product was added to an epoxy system cured with JEFFAMINE~ D-230 as in Examples 3 to 14. The results are shown in Table III below.

~ ' .
.

E~ .

. ~ . . . .

TABLE III
Examples Formulation 15 16 17 18 19 Epoxy, pbw (eq. 190) 100 100 100 100 100 Curing agent, pbw1) 30 30 30 30 30 Diureide pbw2) 0 5 10 20 30 Tensile shear, psi3) 980 1180 1170 1010 830 l)"JEFFAMINE~ D-230"
2~ M.w. ~400; 10.3% N, 0.02 me~. total amine/g.
3) 7 days at room temperature.

A comparison of the tensile shear in the above Table and corresponding values in Tables I and II demonstrate the dramatically superior adhesive properties of the resins con-taining additives in accordance with the instant invention.
EXAMPLES 20 and 21 In these Examples, the bisureide of Example 1 was added to an epoxy system cured with a polyamidopolyamine sold under the tradename of "VERSAMID~ 140" by General Mills, Chem.
Div., Minn., Minn. 55435. The formulation and properties of the cured products are shown in Table IV below. These examples demonstrate the improvement in the adhesive strength experienced in using the cured epoxy containing the additive as opposed to that using the polyamidopolyamine alone.
' ~ .

- B ~33~ ~ ~
::

TABLE IV
Examples -Formulation 20 21 Epoxy, pbw (Eq. 190~ 100 100 VERSAMID~ 140, pbw 40 40 Diureide, pbw1) - lO
Tensile shear strength, psi at cure conditions2) 24 hrs 3000 2800 48 hrs 3000 3400 72 hrs - 3700 96 hrs 2300 3600 7 days 1700 4750 48 hrs, 30 days3) 1040 4000 72 hrs, 70 days4) 3500 4200 l) The product of Example l.
2) Cured at room temperature.
3) After cure, sample immersed in water for indicated time.
- 4) After cure, sample placed in Weatherometer having cycle I full light, 12 min. water spray/2 hrs for indicated time.

-~ EXAMPLES 22 and 23 I In these Examples, the bisureide prepared in Example ll 1 was added to an epoxy system cured with triethylenetetra-mine at room temperature, and compared with a control system, cured under the same conditions but without the additive. The formulations and properties of the cured resins are shown in Table V below. Considerable improvement in bond strength can be observed at all stages of curing in the resin which included the bisureide additive.

~ .

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: ~ .
.... : .... ~

TABLE V
Examples Formulation 22 23 Epoxy, pbw (Eq. 190) 100 100 Triethylenetetramine, pbw12 12 Diureide, pbwl) - 20 Ténsile shear strength, psi at cure conditions2) 24 hrs 400 650 48 hrs 3) 1100 72 hrs 700 1650 96 hrs 600 1300 7 days 800 2200 72 hrs, 70 days4) 1600 4400 1) Product of Example 1.
2) Cures at room temperature.
3) Panel broke while cutting samples; bond brittle, could not test.
4) After cure, sample placed in Weatherometer having cycle full light, 12 min. water spray/2 hrs for indicated time.

EX~MPLES 24 to 27 In this Example the diureide prepared in Example l ~as added in varying amounts to amine cured systems. In two runs a polyoxypropylenediamine o~ m.w. 400 and an amine equivalence of 105 was used and in two others a polyoxy-; propylenetriamine of m.w. 400 with an amine equivalence of ` about 70. The results are shown in Table VI below.
, .,,.- ~

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TABLE VI
Exam~les Formulation 24 25 26 27 Epoxy, pbw (Eq. 190) 100 100 100 100 Curing agent (diamine) pbw1) 50 50 - -Curing agent (triamine) pbw2) _ - 45 45 Diureide, pbw3) lO 20 10 20 Accelerator, pbw4) 10 10 10 10 _ Tensile shear strength, psi5) 2100 2300 3400 3300 1) Polyoxypropylenediamine sold under the tradename JEFFAMINE~ D-400.
2) Polyoxypropylenetriamine sold under the tradename JEFFAMINE~ T-403.
3) Product of Example 1.
4) "Accelerator 398".

5) Cured for 7 days at room temperature.

These Examples show that the additives are less effective in increasing adhesive strength when used in resins wherein polyether polyamine curing agents having an equival-ence over about 70 is used.
EXAMPLES ?8 to 34 These Examples demonstrated further the unexpectedadhesive properties of the resins prepared using the additives in accordance with the instant invention. The peel strength of various resins was tested as shown in Table VII below.

: . .

TABLE VII
Example No. 28 29 Formulation prepared in accordance with previous Example Nos. 3 6 Diureide, pbw 0 20 Peel strength, pli. 7.624.7 Example No. 30 31- 32 33 3~4 Formulation prepared in accordance with previous Example Nos. 10 11 12 13 14 Diureide, pbw 5 10 20 30 40 Peel strength, pli. 5.9 8.3 25.3 34.7 35.9 EXAMPLES 35 to 38 In the following Examples, castings of cured resin were prepared using the additive in accordance with the instant invention. The results are shown in Table VIII below.
.
TABLE VIII ::
. .
__ ExamDles Formulation .35 36 37 38 Epoxy, pbw (Eq. 190) 100 100 100 100 Curing agent, ~bWl) 30 30 30 30 Diureide, pbw2~ - 5 10 20.
Accelerator, pbw3) 10 10 10 10 ProPert--ies4) IZOD lmpact strength, ft-lbs/in 0.36 0.48 0.70 0.90 Tensile strength, psi 7400 8700 7700 6500 Tensile modulus, psi469000 424000385000 343000 Elongation at break, % 1.7 3.2 9.7 8.4 Flexural strength, psi 9800 13500 12200 10600 Flexural modulus, psi 483000 464000 421000 379000 HDT, C, 264 psi/66 psi 47/48 47/49 49/50.5 49/50 Shore D hardness,.
' 0-10 sec 85-84 84-82 78-75 81-78 ~37~

.
. .

. . . . .
. - -1) JEFFAMINE~ D-230 2) Product of Example 1.
3) "Accelerator 398".
4) 1/8" coating cured at room temperature for 7 days.

EXAMPLES 39 to 48 - The following Examples show the resins containing the additives in accordance with the instant invention are unexpectedly resistant to thermal shock.
The formulations for the following Examples were pre-pared in accordance with Examples 3 and 4 above. Approxim-ately 50 g samples were utilized to encapsulate washers (1" o.d., 3/8" i.d., 1/16" thick) supported by 1/4" ring of filter paper cut from Whatham 19 x 19 mm. cellulose extrac-tion thimble. The encapsulations were formed in aluminium milk test evaporating dishes (5 cm dia. x 1 cm deep). The results are shown in Table IX below.1) TABLE IX
ExamPles Formulation 39 40 41 42 43 44 45 46 47 48 I2) (No. cracked) 1 4 1 0 0 0 II3) (No. cracked) 0 0 0 0 0 0 0 0 0 0 ;-1) Thermal cycle: oven at 160C (30 mins), bath at -40C
(15 mins), room temperature (15 mins). Examined for cracking and, if unchanged, recycled to oven.
2) Prepared as in Example 3.
3) Prepared as in Example 4.

EXAMPLES 49 to 52 .. ._ _ .
In these Examples the bisureide of Example 1 was added to an epoxy system containing a diethylene glycol bis(propyl-amine) curing agent sold under the tradename ZZL-0822 by ~ B
f~V

Union Carbide. The formulations and properties of the cured resins are shown in Ta~le X below.
TABLE X
Examples Formulation 49 50 51 52 Epoxy (Eq. 190) 100 lO0 100 100 Diethylene glycol -bis(propylamine)1) 30 30 30 30 Bisureide2) - 2 5 10 -Tensile shear, psi 1700 3100 3900 3800 1~ ZZL-0822.
2) Product of Example 1.
This example demonstrates the improved adhesive strength of the epoxy cured with the additive over the epoxy , cured with the diethylene glycol bis(propylamine) alone.

In this Example, a polyether diamide terminated additive was prepared. Into a suitable reaction vessel, equipped with stirring apparatus, thermometer, reflux con-denser, and Dean-Stark trap were added 971 grams (0.5 mole) of "JEFFAMINE~ D-2000", 76.5 grams (1.5 moles) of 90% by weight aqueous formic acid, and 200 ml of toluene. The vessel was flushed with nitrogen and its contents were stirred under a nitrogen pad for 2 hours at reflux. An aqueous phase was separated in the Dean-Stark trap. The crude reaction residue was then stripped in a rotary evapor-ator at 97C/0.4 mm Hg to produce a viscous residue which upon analysis showed 1.64% ~, 0.07 meq. total amine/g.

¦ EXAMPLES 54_to 57 ... .... - .
In these Examples epoxy resins were prepared and ` 30 tested as in Examples 3 to 8. The data, which are for .
~ -39-B
. ~ ,.. .. . . . . . ... . . . . . . .. .. . . . ..
.

comparative purposes only, are presented in the following Table XI.

TABLE XI
Examples Formulation 54 _ 56 57 Epoxide, pbw (Eq. 190) 100 100 100 100 Curing agent, pbw1) 30 30 30 30 Accelerator, pbw2) 10 10 0 0 Bisformamide3) 0 30 0 30 Tensile shear, psi 1050 1500 980 1500 1) JEFFAMINE~ D-230.
2) Accelerator 398.
3) The product of Example 53.
This Example demonstrates the improved adhesion strength of the epoxy formulation when amounts of the bis-amide are added to an epoxy formulation cured with a polyoxy-propylenediamine of m.w. 230.

' 20 EXAMPLE 58 In this Example, a polyether bis(benzamide~ additive was prepared for use in accordance with the invention. Using the equipment and procedures of Example 53, 1330 grams (0.696 moles) of "JEFFAMINE~ D-2000", 170 grams of benzoic acid (1.393 moles) and 50 ml of benzene were charged to a suitable reaction vessel. The resultant mixture was flushed with nitrogen and stirred under nitrogen at reflux (156 to 1 240C) with continuous water removal (85% of theoretical).
;l A vacuum was slowly applied over about a one hour period to , 30 facilitate the removal of the remainder of the water. The , ~:

~ ' -40-( .

mixture was then stirred under vacuum (185C/30 mm Hg~ for an additional hour. Upon cooling, the light brown, viscous li~uid reaction product was shown to consist substantially of the bis(benzamide) material.

Thi~ Example shows a substituted amide used as an additive in accordance with the instant invention. Using ;
the bis(benzamide) prepared in Example 58 as the additive, an anhydride cured formulation was prepared as shown in ' Table XII.

TABLE XII
Example Formulation 57 Epoxy resin (Eq. l9O) 100 Curing agent, pbw1) 85 -Additive, pbw2) 20 Accelerator3) 10 Appearance of casting after cure 24 hrs, room temp.Opaque, white 3 hrs, 125C Opaque, white 1) "Nadic Methyl Anhydride~".
2) Product of Example 58.
3) "DMP~-10" sold by Rohm and Haas, Philadelphia, Pa. 19105.
The opaque appearance of the casting after cure indi-cates the presence of the improved thermal shock properties.

In this Example an amino terminated polyether urey-lene additive was prepared. Into a suitable reaction vessel equipped with stirring apparatus, were admixed 62.9 lb of a 2000 m.w. polyoxypropylenediamine (O.032 moles) having an .

~ . . .

.: .... . . .. . ... . . ~

analysis of 1.0 milliequivalents (meq.) primary amine/g and 0.99 lb (0.016 moles) of urea. The mixture was flushed with nitrogen and stirred under nitrogen while being gradually heated to 183C. This temperature was maintained until evolution of ammonia had ceased. The resultant crude reac-tion product was then stripped at 150C/l mm Hg to produce a viscous liquid. This product was then filtered through a filtering cloth and analyzed showing the following: 1.57% N, 0.53 meq. total amine/g, 0.52 meq. primary amine/g, 0.10%
water.
EXAMPLES 61 to 63 ~;
In these Examples epoxy resins were prepared and tested as in Examples 3 to 8. The data, which are for com-parative purposes only, are presented in the following Table XIII.

TABLE XIII

Exam~le Formulation 61 62 63 Epoxide, pbw ~Eq. 190) 100 100 100 Curing agent, pbwl) 30 29 30 Accelerator, pbW2 ) 10 10 10 ! Poly3ether ureylene, i pbw ) - 29 14 Tenslle shear strength4 psi at cure conditions ) ! 24 hrs 1400 1600 2300 48 hrs 1000 2200 3300 72 hrs 1400 2400 3000 96 hrs 1400 3100 3700 7 days 1500 3250 3900 72 hrs, 30 days5)1600 2900 3400 72 hrs, 30 days6)1800 3500 3800 , , .

` -1) "JEFFAMINE~ D-230".
2) "Accelerator 398". -3) The product of Example 60.
4) Cures at room temperature.
5) After cure, sample immersed in water for indicated time.

6) After cure, sample placed in Weatherometer having cycle full light, 18 min water spray/2 hrs for indicated time.

This Example demonstrates the improved adhesion strength of the epoxy formulation when amounts of the amino terminated polyether ureylene are added to an epoxy formul-ation cured with a polyoxypropylenediamine of m.w. 230.

EXAMPLES 64 to 67 In this Example the polyether ureylene prepared in accordance with Example 60 was added in varying amounts to amine cured systems. In these four runs a polyoxypropylene-diamine of m.w. 400 and an amine equivalence of 105 was used.
The results are shown in Table XIV below.

TABLE ~IV
ExamPles Formulatlon 64 65 66 67 Epoxy, pbw (Eq. 190) 100 100 100 100 Curing agent (diamine)1) 28 49 54 55 Polyether ureylene2) 250 49 13 0 Tensile shear strength, pSi3 ) 3001900 3400 3900 1) JEFFAMINE~ D-400.
2) Product of Example 60.
3) Cure: 2 hrs, 80C; 3 hrs, 125C.

.
This Example shows that the additive is less effect-ive in increasing adhesive strength when used in resins wherein polyether polyamine curing agents having an eguiv-ale~ce over about 70 is used.
': ,'.~ , , B ~43~
;

- . - . . . - - -: ~ -EXAMPLES 68 to 70 In these Examples, the amino-terminated polyether ureylene of Example 60 was added to an epoxy system cured with a polyamidopolyamine ("VERSAMID~ 140", see Examples 20 and 21). The formulation and properties of the cured products are shown in Table XV below. These Examples demonstrate the improvement in the adhesive strength experienced in using the cured epoxy containing the additive as opposed to that using the polyamidopolyamine alone.
TABLE XV
Examples Formulation 68 69 70 Epoxy, pbw (Eq. 190) 100 100 100 ;
VERSAMID~ 140 40 40 40 Polyether Ureylene, pbwl) _ 5 10 Accelerator, pbw2) 10 10 10 Tensile shear strength, psi, at cure conditions3)13701890 3120 1) The product of Example 60.
2) "Accelerator 398".
3) Cured at room temperature.

EXAMPLES 71 to 74 In these Examples the amino-terminated polyether urey-lene prepared in Example 60 was added to an epoxy system cured with triethylenetetramine at room temperature and compared with a control system cured under the same conditions but without the additive. The formulations and properties of the cured resins are shown in Table XVI below. Considerable improvement in bond strength can be observed in the resin which included the polyether ureylene additive.

~: "

~ :

TABLE XVI
. ._ , _ Examples Formulation 71 72 73 74 Epoxy, pbw (Eq. 190) 100 100 100 100 Triethylenetetramine, pbw 10 10 10 10 Polyether ureylene, pbwl) - 5 10 20 Tensile shear stren~th, psi at cure conditions2 820 1190 1850 1590 1) Product of Example 60.
2) Cured at room temperature.

. _ :
In this Example a lower molecular weight amine ter-minated ureylene containing compound was used as an additive to show the unexpected properties of the higher molecular weight material.
First, a material was prepared in accordance with the procedure of Example 60 to yield a di-primary amLno termin-ated ureylene linked polyoxyalkylene containing material of m.w. about 800.
The above prepared material was then formulated into a resin as in Example 62. The resulting resin was poured into separate containers. Half were cured at room tempera-ture, the remainder at elevated t~mperature. The results are shown in Table XVII below.

1, .
TABLE X II

Example Formulation 75 Epoxy, pbw (Eq. 190) 100 Additive, pbwl) 14 Curing agent, pbw2) 28 Appearance of castIng after cure:
24 hrs at room temperature clear 3Q 3 hrs at 125C - clear . ' - ~45~
`' -. . . .

1) 800 m.w. material formulated above 2) "JEFFAMINE~ D-230".
The above Example indicates the lack of the adhesive properties and the lack of the optical shift.

In this Example the polyether ureylene prepared in Example 60 was added in varying amounts to the indicated -amine cured system. In the following run a polyoxypropylene-diamine of m.w. 400 and an amine equivalence of about 70 was used. The results are shown in Table XVIII below.

TABLE XVIII
Example Formulation 76 Epoxy, pbw (Eq. 190) 100 Curing agent, triamine1) 40 Polyether ureylene2) 10 ;~
Appearance of casting after cure:
24 hrs at room temperatureOpaque, white 3 hrs at 125C Opaque, white 1) "JEFFAMINE~ T-403".
2) Product produced in Example 60.

In this Example an amino terminated polyether succin-imide additive was prepared. Into a suitable, clean, dry, reaction vessel, equipped with thermometer, stirring apparatus, reflux apparatus, and Dean-Stark trap were added 750 grams (0.39 mole) of "JEFFAMINE~ D-2000", 18.4 grams (0.183 mole) of maleic anhydride and 50 grams of benzene. This mixture was heated at reflux (pot temperature 146 - 167C) for 2.25 hours until azeotropic water removal (2.3 grams of H20) had ceased. Benzene was then removed from the crude reaction ' ' ' .

~ B -46--' - mixture until a pot temperature of 205C was attained. The remaining reaction product was then stripped at 180C/3 mm Hg to produce a viscous residue which, upon analysis, showed O.64 meq. total amine/g., O.43 me~. primary amine/g., 0.009 meq. acidity/g. IR analysis indicated the presence of the succinimide group.

EXAMPLES 78 to 81 In these Examples epoxy resins were prepared and tested as in Examples 3 to 8. The data, which are for comp~rative purposes only, are presented in the following Table XIX.

TABLE XIX
ExamDles Formulations _ 79 80 81 Epoxide, pbw (Eq. 190) 100 100 100 100 Curing agent, pbw1) 30 30 30 30 Accelerator, pbw2) 10 10 10 10 Polyether Succinimide3) 0 75 14 29 Properties4) Tensile shear strength, psi 12503860 4110 3310 Peel strength, pli 7.610.1 23.2 38.4 1) "JEFFANINE~ D-230".
2) "Accelerator 398".
3) The product of Example 77.
4) Cure conditions: room temperature, 7 days.
. .
This Example demonstrates the improved adhesion strength of the epoxy formulation when amounts of the poly-ether succinimide are added to an epoxy formulation cured with a polyoxypropylenediamine of m.w. 230.
~ ' .- .

.

z This E~ample further shows the use of the additive in accordance with the instant in~ention with a different amine curing agent. Using the compound prepared in Example 77 as the additive, a cured formulation was prepared as shown in Table XX.

TABLE XX
Formulation Epoxy resin (Eq. 190) 100 Curing agent, pbw1) 57 Additive, pbw2) 24 Accelerator3) 10 Appearance of casting after cure:
24 hrs at room temperatureOpaque, white 3 hrs at 125C Opaque, white l) "JEFFAMINE~ D-400".
2) The product of Example 77.
3) "Accelerator 398".
The opaque appearance of the casting after cure indicates the presence of the improved adhesive properties.

'' ,-.

~ -48-.~, .

Claims (18)

Set A

The embodiments of the invention in which an exclus-ive property or privilege is claimed are defined as follows:

1. A curable epoxy resin composition which comprises:
(i) a vicinal polyepoxide having an epoxide equiv-alent of greater than 1.8;
(ii) a curing amount of a polyamine curing agent having at least 3 reactive amino hydrogens; and, (iii) an effective amount of an additive of the formula (I) in which R is hydrogen; a branched or straight chain alkyl, alkenyl, or alkadienyl radical having up to 10 carbon atoms;
a monocyclic aryl, alkaryl or aralkyl radical having from 6 to 10 carbon atoms; an aminoethyl or aminopropyl radical;
or a radical of the formula R'-CO- or R'-NH-CO-in which R' is hydrogen; a branched or straight chain alkyl, alkenyl or alkadienyl radical having up to 10 carbon atoms;
or a monocyclic aryl, alkaryl or aralkyl radical having up to 10 carbon atoms;
X is hydrogen, methyl or ethyl;
Y has the same meaning as R; or is a -CO-R radical; a radical of the formula or a radical of the formula in which R is an alkylene, cycloalkylene, arylene, aralky-lene or alkarylene radical;
R is a radical of the formula Z is an alkylene radical having 2 to 5 carbon atoms; and each n is from 15 to 25.

2. A composition as claimed in claim 1 which com-prises an effective amount of a curing accelerator.

3. A composition as claimed in claim 2 wherein the curing accelerator is a salt of a phenol, a salicyclic acid, an amine salt of a fatty acid, a tertiary amine, or a mix-ture of piperazine and an alkanolamine.

4. A composition as in claim 1 wherein the additive is a diureide of the formula ( II) in which R' is hydrogen; a branched or straight chain alkyl, alkenyl or alkadienyl radical having up to 10 carbon atoms;
or a monocyclic aryl, alkaryl or aralkyl radical having up to 10 carbon atoms;
X is hydrogen; methyl or ethyl;
Z is an alkylene radical having 2 to 5 carbon atoms; and n is from 15 to 25.

5. A composition as claimed in claim 4 wherein R' is hydrogen or alkyl; X is methyl; Z is 1,2-propylene; and n is from 16 to 19.

6. A composition as claimed in claim 4 wherein R' is hydrogen, methyl, ethyl, n-propyl or n-butyl.

7. A composition as in claim 1 wherein the additive is an amide of the formula ( III) in which R' is hydrogen; a branched or straight chain alkyl, alkenyl or alkadienyl radical having up to 10 carbon atoms;
or a monocyclic aryl, alkaryl or aralkyl radical having up to 10 carbon atoms;
X is hydrogen, methyl or ethyl;
Z is an alkylene radical having 2 to 5 carbon atoms; and n is from 15 to 25.

8. A composition as claimed in claim 7 wherein R' is hydrogen or alkyl; X is methyl; Z is 1,2-propylene; and n is from 16 to 19.

9. A composition as claimed in claim 7 wherein R' is hydrogen, methyl, ethyl, n-propyl or n-butyl.

10. A composition as in claim 1 wherein the additive is a ureylene of the formula (IV) in which R is hydrogen; a branched or straight chain alkyl, alkenyl, or alkadienyl radical having up to 10 carbon atoms;
a monocyclic aryl, alkaryl or aralkyl radical having from 6 to 10 carbon atoms; or an aminoethyl or aminopropyl radical;
X is hydrogen, methyl or ethyl;
Y' is a -CO- radical or a radical of the formula -CO-NH-R -NH-CO
in which R2 is an alkylene, cycloalkylene, arylene, aralky-lene or alkarylene radical;
Z is an alkylene radical having 2 to 5 carbon atoms; and each n is from 15 to 25.

11. A composition as claimed in claim 10 wherein Y' is CO; R is hydrogen, alkyl of from 1 to 4 carbon atoms; or 2-aminoproyl radical; X is methyl; Z is 1,2-propylene; and _ is from 16 to 19.

12. A composition as claimed in claim 10 wherein R
is hydrogen, methyl, ethyl, n-propyl or n-butyl.

13. A composition as in Claim 1 wherein the additive is a succinimide of the formula (V) in which R is hydrogen; a branched or straight chain alkyl, alkenyl, or alkadienyl radical having up to 10 carbon atoms;
a monocyclic aryl, alkaryl or aralkyl radical having from 6 to 10 carbon atoms; or an aminoethyl or aminopropyl radical;
X is hydrogen, methyl or ethyl;
Y2 is a radical of the formula Z is an alkylene radical having 2 to 5 carbon atoms; and n is from 15 to 25.

14. A composition as claimed in claim 13 wherein R
is hydrogen, alkyl of from 1 to 4 carbon atoms; or a 2-aminopropyl radical; X is methyl; Z is 1,2-propylene; and n is from 16 to 19.

15. A composition as claimed in claim 13 wherein R
is hydrogen, methyl, ethyl, n-propyl or n-butyl.

16. A composition as in claim 1 wherein the curing agent is a polyoxyalkylene polyamine of the formula or (VI) (VII) wherein X is hydrogen, methyl or ethyl; Z is a hydrocarbon radical having 2 to 5 carbon atoms and having a value of from 2 to 4; m is a number from 1 to 15, r is a number from 2 to 4; and p is 2 or 3.

17. A composition as in claim 1 which comprises:
(i) 100 parts by weight of the vicinal poly-epoxide;
(ii) an amount of the polyamine curing agent suf-ficient to provide from 0.8 to 1.2 equivalents of amino group per epoxy equivalent of the vicinal polyepoxide;

(iii) from 5 to 50 parts by weight of the additive;
and optionally (iv) from 1 to 10 parts by weight of the acceler-ator.

18. A cured epoxy resin composition obtained by curing a curable composition as claimed in claim 1.