CA1114095A - Polyether epoxy additives - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Resistance to thermal shock of certain anhydride cured epoxy resins is unexpectedly enhanced by addition of certain polyether additives. This superior resis-tance does not appreciably compromise heat deflection properties. The resins comprise a vicinal polyepoxide, a curing amount of a certain bicyclic anhydride and an effective amount of a polyether diureide having terminal ureido groups or 2 polyether diamide having terminal amido groups and a molecular weight of from about 2000 to about 3000.

Description

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This invention relate~ to curable epoxy resins having increased thermal shock resistance; and, more particularly, to certain anhydride cured epoxy resins containing certain polyether diureides or diamide additives.

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 agent is generally the anhydrides.

The most commonly used anhydride curing aO~ents are difunctional ma~erials ~uch as maleic anhydride,and phthalic anhydride, as well a~ tetrafunctional materials such as pyro~ellitic dianhydride.

It is known to use polyamides as epoxy curing agents.
Simple amides such as acetamide, benzamide and adlpamide have been used, but low activity and/or solubility require use of basic cataly~ts. The advantages and disadvantages of polyamides as curing agents is discussed in Handbook of EvoxY
Resins by Henry Lee and K. Neville~, McGraw Hill Book Co., New York, 1967, but, generally, the hydrogen of primary or ~econdary amides is weakly reactive with epoxy groups.

Also known to be effective as epoxy curing agents or co-curing agents are various ureas and substituted ureas, such as tho~e disclosed in U.S. Patents No.3,294,749;

2,713,569; 3,386,956; 3,386,955; 2,855,372 and 3,639,338, which are useful as either 901e curing agents or as curing ; accelarators.

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Aliphatic or aromatic compounds having a single terminal ureido group are well known. It has been disclosed in U.S. Patent No. 2,145,242 that diureido terminated aliphatic compounds can be produced by reacting urea with an aliphatic diamine wherein each terminal amin~ group has at lea~t one la~ile hydrogen atom. Other substituted ureas are disclosed in U.S. Patent No.3,965,072.

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Epoxy resins for casting, embedding or encapsulating must withstand repeated cycles of high and low temperatures without cracking. Lowering the temperature, however, increases stress due to shrinkage and reduces the ability of the resin to flow and thereby to relieve the stress.

Anhydride cured resins are useful in applications where high heat deflection is required, but such materials are brittle and thu~ have a low resistance to thermal shock.
Diluents and modifier~ do improve thermal shock reslstance properties but, unfortunately, adverse}y influence the heat de~lection properties, as 3hown in May and Tanaka, Epox~

Re~ins, New York, 1973, p.299. Likewise, pla~ticizers have not found wide acceptance in epoxy technology primarily because most of them are inc~mpatible with the cured resins.
.
It has now been unexpectedly found that a specific diureide or diamide terminated polyoxyalkylene material having a molecular weight of from 2000 to 3000, when employed as an epoxy add tive, provides cured epoxy resin compositions exhibiting outqtanding thermal shock resiqtance.
Specifically, epoxy res.ins incorporating these additive~, upon curing with a specific bicyclic amhydrida curing agent, provide a material with high heat deflection and superior resistance to thermal shock.

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.

The results o~ incorporating the additives according to the present invention are particularly qurprisin~ in ll~rht of the fact that similar ureido terminated compounds of lower molecular weight do not effect the same improvement in the cured reRin. The cured epoxy resin compo~itions o~ t~e present invention are useful as coatings, casting~, and senlants.

The present invention provide~ a curable epoxy resin composition which comprises-(i) a vicinal polyepoxide having an epoxide equivalent of greater than 1.8.
(ii) a curing amount of a substituted bicyclic vicinal anhydride curing agent; and, . (iii) an effective amount of an additive comprising .15 a polyether diureide or diamide having terminal ureidé or amido groups and a molecular weight o~ from 2000 to 3000.
:
The present invention also provides epoxy resin compositions obtained by curing the resins described above.

In one aspect, a curable epoxy re~in composition having superior thermal shock resistance comprises a vicinal polyepoxide; a curing amount of bicyclic vicinal anhydride curing agent comprising a Diels-Alder adduct o~ a substituted . cyclopentadiene and maleic anhydride; and, an e~fective amount o~ the polyether diureide or diamide additive.

In accordance with a pre~erred embodiment, a diglycidyl ether o~ 4,4'-isopropylidene bisphenol, a curing amount of a methyl-bicyclo C2,2~1~ heptene-2,3-dicarboxylic anhydride ' , ~ ' : ' curing agent, a dimethylaminomethyl substituted phenol accelerator and an effective amount o~ a polyether diureide or diamide having terminal ureido or amido groups and a molecular weight of about 2000 are utilized to ~orm a resin.

According to the present invention, blends o~ a polyepoxide, an anhydride curing agent and the diureido or diamido terminated polyether containing compounds and, optionally, an accelerator are thoroughly mixed, and cured in accordance with conventional methods to provide cured epoxy resins having unexpectedly superior thermal shock resistance while maintaining heat deflection properties.

Generally the vicinal polyepoxide containing compositions which are amine cured are organic materials having an average .
o~ at least 1.8 reactive 1,2-epoxy groups per molecule. These polyepoxide materials can be monomeric or polymeric, ~aturated or unsaturated, aliphatic cyclo-aliphatic, aromatic or heterocyclia, and may be substituted if desired with other su~stituents besides the epoxy groups, e.g., hydroxyl groups, ether radicals, or aromatic halogen atoms.

Preferred polyepoxides are those of glycidyl ethers prepared by epoXidizing the corresponding allyl ethers or reacting, by known procedures, a molar excess o~
epichlorohydrin and an aromatic polyhydroxyl compound, i.e., isopropylidene bisphenol~ a novolac, or resorcinol. The epoxy derivatives of methylene or isopropylidene bisphenols are especially pre~erred.

s 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, list of suitable dihydric phenols includes

4,4'-isopropylidene bisphenol, 2,4'-dihydroxydiphenylethyl-methane, 3,3'-dihydroxydiphenol-diethylmethane, 3,4-di-hydroxyphenylmethylpropylmethane, 2,3'-dihydroxydiphenyl-ethylphenylmethane, 4,4'-dihydroxydiphenylpropylphenyl-methane, 4,4'-dihydroxydiphenylbutylphenylmethane, 2,2'-di-hydroxydiphenylditolylmethane, 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, hydro-quinone, and substituted hydroguinones, e.g., methylhydro-quinone.
Among the polyhydric alcohols which can be co-reacted with an epihalohydrin to provide these resinous epoxy poly-ethers are such compounds as ethylene glycol, propyleneglycols, butylene glycols, pentane diols, bis(4-hydroxy-cyclohexyl)dimethylmethane, 1,4-dimethylolbenzene, glycer-ol, 1,2,6-hexanetriol, trimethylolpropane, mannitol, sorbitol, erythritol, pentaerythritol, their dimers, trimers and higher polymers, e.g., polyethylene glycols, polypropylene glycols, triglycerol, dipentaerythritol, polyallyl alcohol, polyhydric thioethers, such as 2,2',3,3'-tetrahydroxydipropylsulfide, mercapto alcohols such as monothioglycerol or dithioglycerol, polyhydric X
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alcohol partial esters, such as monostearin or pentaerythritol monoacetate and halogenated polyhydric alcohols such as the monochlorohydrins of glycerol, sorbitol or pentaerythritol.

Another class of polymeric polyepoxides which can be anhydride cured and~used in accordance with the present invention includes the epoxy novolac resi~s obtained by reacting, preferably in the presence of a basic catalyst, e.g., sodium or potassium hydroxide, an epihalohydrin, such as epichlorohydrin, with the resinous conden~ate of an àldehyde, e.g., formaldehyde and either a monohydric phenol, e.g., phenol itself, or a polyhydric phenol. Further detail~
collcerning the nature and preparation of these epoxy novolac regins can be obtained in the previously mentioned Handbook of Epoxv Resins by Lee and Neville.
It will be appreciated by those skilled in the art that the polyepoxide compo~itions which are useful according to the practice of the present invention are not limited to those containing the above described polyepoxides, but that these polyepoxides are to be considered merely as being representative o~ the class of polyepoxides as a whole.

The anhydride curing agents which can be utilized in accordance with the instant invention are generally alkyl substituted bicyclic vicinal anhydrides, for example, the Diels-Alder adduct of maleic anhydride and ~ substituted cyclopentadiene. Preferred compounds generally have the - formula-R~ C \3 wh~rein R is alkyl and, more preferably, alkyl of from 1 to 4 carbon atoms. Preferred alkyl groups include methyl, et]lyl, propyl, and n-butyl. The most preferred alkyl is methyl. The most preferred anhydride is methyl-bicyclo ~,2,1¦ heptene -2,3-dicarboxylic anhydride.

The polyether diureide and diamide additive can generally be described as polyoxyalkylene containing materials having terminal ureido or amido group~ and a molecular weight of ~.

from 2000 to 3000. More specifically, these compounds are polyoxyalkylene compounds having terminal ureido or amido groups, and having the formula:
O
Il rH-NH-C_NH_(IH-IHO)nl2-Z or X H

~H-U-NH-(lH_lHo)n~ 2-Z
X H

wherein X i~ hydrogen, methyl or ethyl; Z is alkylene having 2 to 5 carbon atoms and n is a number such that the molecule of the above formula has a molecular weight of from Z000 to 3000. The preferred diureides and diamides are o~ the above formulae wherein Z is a 1,2-propylene radical; and n is a number from 16 to 19.

The polyether diureide compound~ can be formed by the reaction of a ureido forming compound with a polyoxyalkylene diamine having a molecular weight such that the ureido containing product has a molecular weight of ~rom 2000 to 3000 at temperatures in the range from 120 to 150 C in a molar - : - ~ --: - '.-, -.. - .. , ., .. . - . -: . .. - -: ~

~L~ 1413.95 ratio of about 2 mole~ of ureido forming compound for each mole of diamine.

Similarly the polyether diamide compounds can be formed by the reaction of an amido ~orming compound with the polyoxyalkylene diamine at a temperature in the range from 25 to 150C 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 compound~ by acylation of the amine reactant.
:' The diamines that are useful in forming the additives are polyoxyalkylene diamines of the formula:

tH2N-(f~~1R~O)n~2 X H

wherel~ X i9 hydrogen, methyl or ethyl;
Z ia alkylene having ~rom 2 to 5 carbon atom~ and, n ~ 9 a number from 15 to 25. Preferred polyoxypropylene diamines are those wherein X is methyl, n is a number from 16 to 19, and Z 19 a 1,2-propylene radical. These polyoxyalkylene poly-; amines can be prepared by known methods as disclosed in U.S.
3~236,895 and U.S. 3,654,370. It will be realized that n a~
represonted herein i9 an average number and not an integer.

The ureido forming compounds are generally those which supply the O-C-NH 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 of the polyoxyalkylenepolyamine are converted directly into ureidO group~.
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While urea is the preferred ureido forming compound, ot~ler ureido forming compound~ can be utilized. Since the polyoxyalkylenepolyamine reactant already contains terminal primary amino groups, isocyanates of the general formula M+~C0 wherein M+ is generally an alkali metal, such as potassium or s~dium, can be used. The preferred isocyanates that can be used in accordance with the instant invention are sodium and potassium isocyanate primarily because of availability.

The amide forming compounds are generally those which supply the formyl (H.C0-) radical. Suitable ~uch compounds include formic acids, the acid chlorides, and the esters.
Acylation reactions that can be utilized are well known and will not be further herein discu~sed.

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In accordance with these known methods, bhe reactants are ~imply mixed in correct molar ratios in a suitable reaction vessel, and heated until the reaction occurs.

The functionality of the polyoxyalkylenepolyamine i9 dependent upon the number of terminal primary amino groups, which in the present instance is 2. It will be realized that each mole of ureido forming compound or amido-forming compound will react with a single terminal primary amino group of the poLyoxyalkylenepolyamine. It is particularly important that, in ~orming the additive compounds used according to the present invention, a specific molar ratio of reactants be maintained. Specifically, about 1 mole of ureido forming compound or amido forming compound for each amino group of the polyoxyalkylenepolyamine is required.
3o Thus, with the diamine, about 2 moles of ureido forming -- 10 -- , " ,. . .

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compound or amido forming compound are utilized. Preferably the reaction iq carried out in the presence of a slight excess of ureido forming compound or amido forming compound to enqure complete con~erqion of the amino group~.

Optionally, the epoxy resin formulationq of the in~tant in~ention can include an "Accelerator" to qpeed the anhydride cure of the epoxy resin, especially at ambient temperatures.
In several applications, such acceleration i9 beneficial, e~pecially when an epoxy resin iB UAed as an adhesive in a flammable environment, thus making elevated temperature cure inconvenient or even hazardous. Lee and Neville~s 'andbook of E~oxv Resin~, pp. 7 to 14 de-qcribes the use of~certain amine-containing compounds as epoxy curing agent-acceierator~.

Accelerators are known in the art which can be utili~ed in a¢cordance with the pre~ent in~ention~ for example tertiary amine~ ~uch as tho~e disclo~ed in U.S. Patent No. 2~839,480.
Preferred accelerator~ in accordance with the invention are dialkylamine sub~tituted aromatic compound~ and, preferably, the diemthylaminomethyl ~ubstituted phenol~.

According to the method of the pre~ent invention, the thermal hock resi9tant propertie9 of certain prior art anhydride oured epoxy resin~ are enhanced by the addition of an effective -amount of a polyether diureide or diamide having terminal~25 ureido~or amido group~ and a molecular weig~t of from 2000 to 3000 a~ hereihbefore desoribed. The amount of additive effectlve in bringing about the improved adhesive property dep-nd~upon the resin, and the use of an accelerator.
G-nerally~, addltive can be utilized in amounts from 5 to 35 partg~br weig~ht, based on one hundred parts by weight of the .
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.... . .. -: . . - . : : . . :, 14~!~5 resin constituent; and, preferably, from 10 to 20 parts by weight.

The exact amount of additive which is effective to in,rease the thermal shock resistance can readily be determined without undue experimentation owing to the fact that a resin mixture containing an effective amount of the addltive will undergo changes which are readily visible as curing proceedc. 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, advantageously, this optical absorption shift enhances the beauty of cast ob~ects and obviates the need to use white pigments or filler~.

Preferably the thermal shock resistant properties of prior art resins are enhanced by addition of an effective amount of the polyoxypropylene diureide or diamide additive based upon the condensation of 2 moles of urea or formic acid with 1 mole of a polyoxypropylenediamine having a molecular weight of 2000. The preferred resins comprise polyglycidyl ethers of polyhydric phenol cured by incorporating therein a curing amount of methyl bicyclo ~2,2,1~ heptene-2,3-dicarboxylic anhydride and a dimethyl-aminomethyl substituted phenol accelerator.

~he curable epoxy re~in composition~ of the instant invention generally comprise a vicinal polyepoxide, a curing amount of the alkyl substituted bicyclic vicinal anhydride curing agent and an effective amount of the polyether diureide or diamide additive. Optionally an accelerator can ba added.

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The anhydride cured resins according to the invention having superior thermal shock resistance without substantial deterioration of heat deflection, are prepared in a conventional manner. The anhydride curing agent i~ mixed with the polyepoxide composition in amounts according to the functional carboxyl equivalent weight of the curing agent ~`
employed. Generally the number of equivalents of carboxyl groups is from 0.8 to 1.2 times the number of epoxide equivalents present in the curable epoxy resin composition, with from 0.9 to a stoichiometric amount being preferred.
When using an accelerator, amounts from 1 to 5 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 application for which the cured resin is intend-d.

The additive is incorporated into the uncured resin by mixing. Preferably, the additive i~ first mixed with the curing agent and/or the accelerator before addition to the resin. The constituents forming the curable material are then ; inbimately mixed by standard methods and degas~ed in the presence of a commercial de-foamer and minute amounts of ~ilicone oils to prevent voids and bubbles.

Although all of the epoxy resins disclosed herein are generally useful in accordance with the invention, those ba~ed on aliphatic compounds are preferably not used exclusively, The presence of reqins containing polyglycidyl ethers of polyhydric phenols in amounts greater than 50~ by weight of the resin constituent, more preferably 80% by weight , .

.: - . . . :
:- - : --~4~5 and most preferably 100% by weight, has been shown greatly to enhance the desirable properties of the cured material.
In accordance with a preferred embodiment, a curable res1n comprises a diglycidyl ether of 4,4'-isopropylidene bisphenol; a curing amount of methyl bicyclo [~,2,1] heptene 2,3-dicarboxylic anhydride as curing agent, a dimethylamino-methyl substituted phenol as accelerator; and, an effective amount of a polyether diureide or diamide having terminal ureido or amido groups and a molecular weight of about 2000.
According to a greatly preferred embodiment, from 80 to 90 parts by weight of curing agent is used per 100 parts by weight of resin.
A preferred ratio of constituents comprises from 1 to

5 parts by weight of accelerator; from 80 to 90 parts by weight of anhydride curing agent; and from 5 to 35 parts by weight of additive, wherein all of the above amounts are based on 100 parts by weight of the resin. Generally, the mixture of epoxy resin, the additive, anhydride curing agent, and the accelerator is allowed to self-cure at elevated temperatures up to 200C, more preferably 100 to 190C, most preferably 135 to 170C.
According to a greatly preferred embodiment, resins of the polyglycidyl ether of polyhydric phenol type are cured by incorporating therein from 80 to 90 parts by weight of methyl bicyclo [2,2,1] heptene-2,3-dicarboxylic anhydride; from 5 to 40 parts by weight of the polyether diureido or diamido terminated polyoxyalkylenepolyamine having a molecular weight of about 2000; and from 1 to 5 parts by weight of a dimethylaminomethyl substituted phenol ~ -accelerator. The composition is cured at temperatures in the range of 100C to 190C to produce products having superior thermal shock resistance in accordance with the invention.

It will further be realized that various conveniently employed additives can be mixed with the polyepoxide containing composition of the invention before final cure.
For example, in certain instances it may be desired to add minor amount~ of other anhydride co-catalysts. Additionally, any compatible conventional pigments, dyes,fillers, flame retarding agents or natural or synthetic resins can be added.

Furthermore, although not pr~ferred, known solvents for poLyepoxide materials, such as toluene, benzene, xylene, dioxane, and ethylene glycol monomethylether, can be used.
The polyepoxide resins containing the additives of the invention can be used in any of the above applications for which polyepoxides are customarily used.

On~ oustanding feature of the compositions according to the pFesent invention i8 that they are opaque upon curing and give a smooth, white lustrous surface, which may be of pa~ticular benefit for certain moulding and casting operation The compositionq of the instant invention can be used as impregnant~, surface coatings, pottings, capsulating compositions, and laminants.

The following Examples illustrate the nature of the present invention but are not intended to be limitative thereof. Examples 1 to 42 de~cribe the preparation and use o~ ureldo terminated additives and Examples 43 to 5~ describe the preparation and use of amido terminated additives.

3o ~5 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) were placed in a suitable reaction vessel, equipped with stirring apparatus. The mixture was flushed with nitrogen and stirred under a nitrogen pad for 2 hours at 130-134C. A second portion of 990 grams (O.5 moles) of ~JEFFAMINE~ D-2000" was added over a 3 hour period at a temperature of about 132C.
The reaction mixture was maintained at 134C for another 70 minutes, during which time the mixture was vigorously stirred to wash the sublimate 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.

A bis(N-substituted ureido) terminated material was prepared, according generally to the procedure of Example 1.
891 g of "JEFFAMINE~ D-2000" was charged to the apparatus described in Example l. In a nitrogen atmosphere over a period of 45 minutes, 109 g of phenylisocyanate were added to the stirred polyoxypropylenediamine at a temperature of about 55C. The temperature was raised to 60C and the mixture was stirred for an additional two hours. The corresponding bis(N-phenylureido) terminated compound was recovered and upon analysis showed 2.2% N; 0.009 meq. total amine/g.

B

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To illustrate the advantage of the polyether ureide additives of this invention, various epoxy formulations employing the diglycidyl ether of` 4,4'-isopropylidene bisphenol were cured with various known polyamine curing agents.
Where indicated, a commercial accelerator was utilized.
Three drops of silicone fluid were added to each formulation to prevent formation of voids and bubbles. After degassing under vac~um, the formulations were cured under the conditions indicated. In appropriate examples, the cured products were sub~ected to standard American Society for Testing Materials (ASTM) tests for Izod impact strength (ASTM de~ignation D-256), flexural strength and modulu~ o~ elasticity in flexure (ASTM designation D-790-66), tensile strength and elongation at break (ASTM designation D-638-64 T), deflection temperature (ASTM designation D-648-56) and hardness (ASTM designation 2240-64 T) and/or hardness Shore D. The abbreviations in the table~, pbw, poi and g. stand for parts by weight, pounds pe~
square inch, and grams, respoctively.

~ n these examples epoxy resins were prepared wherein the diglycidyl ether o~ 4,4'-i~opropylidene bisphenol was cured with methyl-bicyclo C2,2,1~ heptene -2,3-dicarboxylic anhydride, and a dimethylaminomethyl substituted phenol accel-rator to which were added the indicated amounts of the diureide prepared in Example 1. The re~ulting resins were used to pour 1/8" panels which were subjected to the ASTM
tests~here~in described. The data, which are ~or comparative purposes only, are presented in the following Table 1.

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s TABLE I
Examples Formulation 3 4 5 Epoxide, pbw (Eq. l9O) 100 lO0 100 Curing agent, pbw1) 85 85 85 Accelerator pbw2) 2.5 2.5 2.5 Bisureide3) 0 10 20 Properties of cured 1/8" panels4) IZOD impact strength, ft./lbs/in 0.22 0.48 0.56 Tensile strength, psi 6500 9700 9700 Tensile modulus, psi 419000 393000 367000 Elongation at break, % 1.6 3.0 5.0 Flexural strength, psi 17200 17700 16000 Flexural modulus, psi 487500 435000 392000 HDT, C, 264 psi/66 psi 122/130 112/121 112/119 Shore D hardness 0-10 sec 89-87 90-88 85-83 )"Nadic Methyl Anhydride~" sold by Allied Chemical Corp-oration, Morristown, NJ 07960 2 )"DMP~-10" sold by Rohm and Haas, Philadelphia, PA 19105 3 )Product of Example 1 4 )Cured 2 hr. at 100C, 1 hr. at 130C, 3 hr. at 150C

EXANPLES 6 to 15 The following Examples show the resins containing the additives in accordance with the present invention are unexpectedly resistant to thermal shock.
~esins for the following Examples were prepared in accordance with the formulations shown in Table II here.
Approximately 50 g samples were utilized to encapsulate washers (1" o.d., 3/8" i.d., 1/16" thick) supported by a -1/4" ring of filter paper cut from Whatham l9 x 19 mm.

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

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

cellulose extraction thimble. The encapsulations were formed in aluminium milk test evaporating dishes (5 cm. dia.
x 1 cm. deep). The results are shown in Table III below.

TABLE II

Formulation A B C D E
Epoxide, pbw (Eq. 190) 100 100 100 100 100 Curing agent, pbw1) 85 85 85 85 85 Accelerator, pbw2) 2.5 2.5 2.5 2.5 2.5 Diureide3) --- 5 10 15 20 TABLE III
ExampleS
Number of samples cracked during cycles 6 7 8 9 10 11 1213 14 15 Formulation4) A 6 1 3 -5) -1) "Nadic Methyl Anhydride~"
2) "DMP~ 10"
3) Product of Example 1 4) 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.
5~ All 10 samples were cracked after cycle 3.

~' - 19 -.. . .

EXAMPLES 16 to 18 In these Examples, epoxy resins were prepared in the same manner as those in Examples 4 and 5, substituting "JEFFAMINE~ D-2000" for the diureide additive. These examples demonstrate that the heat deflection temperature is significantly lower when using the l'JEFFAMINE~ D-2000"
additive as opposed to the polyether diureido terminated additive of the instant invention. Table IV shows the formulation of Examples 16 to 18 with their corresponding heat deflection temperature.

TABLE IV
Examples Formulation 16 17 18 .
Epoxide, (E~. 190) 100 100 100 Curing agent/
pbwl) 85 85 85 Accelerator pbw2) 2.5 2.5 2.5 Additive, pbw3) 0 10 20 Properties of cured 1/8" unfilled castings4) HDT, C, 264 psi/66 psi 122/13090.5/10088/98 1) "Nadic Methyl Anhydride~"
2) "DMP~-10"
3) "JEFFANINE~ D-2000"
4) Cured as in Examples 3 to 5 In order to demonstrate the unexpectedly superior properties of resins prepared in accordance with the present invention, commercial anhydride curing agents other than the -~

. .

~s alkyl-bicyclo [2,2,1] heptene dicarboxylic anhydrides of the instant invention are used.

ExAMæLEs 19 to 21 In these Examples hexahydrophthalic anhydride is used as the curing agent with a benzyldimethylamine accelerator.
The amount of polyether diureide, prepared in accordance with Example 1, which must be utilized to provide thermal shock protection is of such a magnitude that deterioration of other physical properties occurs. Table V presents the formulations and properties of the cured resins produced with the alternate curing agent.

TABLE V
Examples Formulation 19 20 21 Epoxy resin (EEW 190), pbw 100 100 100 Hexahydrophthalic anhydride, pbw 78 78 78 Benzyldimet~ylamine, pbw 1 l 1 -~
Diureide, pbw1) 0 20 50 Properties of cured 1/8" unfilled castings2) IZOD impact strength, ft./lbs/in 0.19 0.36 0.41 Tensile strength, psi 12200 9400 5400 Tensile modulus, psi 393000 334000 204000 Elongation at break, % 8.0 4.9 5.2 Flexural strength, psi 18600 15100 9900 Flexural modulus, psi 439000 349000 255000 H~T, C, 264 psi/66 psi 120/120 100/109 75/93 Shore D Hardness 0-10 sec. 90-85 90-86 85-80 1)Prepared in accordance with Example 1 2)Cure cycle: 2 hr~ at 125C, 3 hr. at 150C

. . .
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- ' : ' ' ' - ~ ' ~ '. , ' EXAMPLES 22 to 31 The following Examples, using the cured resins of Examples 19 to 21, demonstrate the diminished thermal shock resistance of these alternately prepared resins as , .. . ..
5 compared with resins prepared in accordance with the instant invention.
Approximately 50g samples were utilized to encapsulate washers as in Examples 6 to 15. The results of tests in which ten samples of each formulation were used are shown in Table VI below~
TABLE VI
Number of samples cracked during cycles 22 23 24 25 26 27 28 29 30 31 Formulation Example 19 4 1 1 0 1 0 0 0 1 0 Example 20 0 1 1 1 1 0 1 1 0 2 Example 21 0 0 0 0 0 0 0 0 1 2 )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. -EXAMPLES 32 to 41 In the following examples epoxy resins are prepared using phthalic anhydride as a curing agent and benzyldi- ;
methylamine as the accelerator. The formulations for these resins are shown in Table VII. The cured resins are then subjected to testing for thermal shock resistance in accord-ance with the procedures of Examples 22 to 31. The results of this testing, in which ten samples of each formulation were used, are shown in Table VIII. These examples demon-strate that the epoxy resins cured in accordance with the instant invention provide improved thermal shock resistance over resins cured with phthalic anhydride.

, 1~1 141}~95 TABLE VII

Formulation1) A B C D
Epoxy resin (Eq. 190), pbw 100 100 100 100 Phthalic anhydride, pbw 75 75 75 75 Benzyldimethylamine, pbw Diureide, pbw2) 0 10 20 40 lo TABLE VIII
Examples Number of samples cracked during cycles3) 32 33 34 35 36 37 38 39 40 41 Formulation C 1 4 1 1 0 0 1 24) - -D 0 9 0 14) 1)Cure cycle: 2 hr. at 125C, 3 hr. at 150C
2 )Prepared in accordance with Example 1 3)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.
4)All 10 samples were cracked after cycle.

In this example, the unexpected selectivity of the additive of the present invention is demonstrated. Using the bis(phenyl urea) compound prepared in Example 2 as the additive, an anhydride cured formulation was prepared as shown in Table IX.

~ .

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

,S

TABLE IX
Formulation Example -Epoxy Resin (Eq. 190) 100 Curing agent, pbw1) 85 Additive, pbw2) 20 Accelerator3) 2.5 Appearance of casting after cure~) Clear 1) "Nadic Methyl Anhydride~"
2) Product of Example 18 3) "DMP~-10"
4) Cured 3 hr. at 125C.
The clear appearance of the casting after cure indicates the absence of the improved properties obtaîned using the bis(phenyl urea) additive in accordance with the instant invention.

In this Example a polyether diamido terminated additive for use in accordance with the instant invention, was prepared.
971 grams ~0.5 mole) of "JEFFAMINE~ D-2000", 76.5 g (1.5 moles) 90% by weight of aqueous formic acid, and 200 ml of toluene were placed in a suitable reaction vessel, equipped with stirring apparatus, thermometer, reflu~ condenser, and Dean-Stark trap, flushed with nitrogen and stirred under a nitrogenpad for 2 hours at reflux. An aquous phase was separated in the Dean-Stark trap. The crude reaction residue was then stripped in a rotary evaporator at 97C/0.4 mm Hg to produce a viscous residue which upon analysis showed 1.64% N, 0.07 me~. total amine/g.

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To illustrate the advantage of the polyether diamide additives of this invention, variouq epoxy formulations em]~loying the diglycidyl ether of 4,4'-isopropylidene bisphenol were cured with various known polyamine curing agents, and subjected to the tests described in Example~ 3 to 5.

EXAMPLES 44 to 46 In these examples epoxy resins were prepared wherein the diglycidyl ether of 4,4'-isopropylidene bisphenol was cured with methyl-bicyclo [2,2, 11 heptene-2,3-dicarboxylic anhydride, and a dimethylaminomethyl substituted phenol accelerator to which were added the indicated amounts of the amide prepared in Example 43. The resulting resins were used to pour 1/8" panels which were subjected to the ASTM tests herein described. The data, which are ~or comparative purposes only, are presented in the foilowing Table X.

TABLE X
Examples Formulations 44 4$ 46 Epoxide, pbw (Eq. 190) 100 100 ~oo Curing agent, pbw ) 85 85 85 Accelerator, pbw2) 2.5 2.5 Z.5 Bisamlde3) 0 10 20 Properties of cured 1/8"
pnnel Y i ) , ~

IZOD impact strength, ~t./lbs/in 0.22 0.28 0.30 Tensile strength, psi 6500 12100 10100 Tensile modulus, psi 419000 454000 358000 Elongation at break, /0 1.6 4.0 4.5 Flexural strength, psi 17200 18000 15000 Flexural modulus, psi 487500 439000 375000 HDT, C, 264 psi/66 psi 122/130 114/123 111/12 Shore D hardnesR, 0-100 sec. 89-87 87-85 87~85 . . .

.
.

1) "Nadic ~ethyl Anhydride~" -2) "DMP~-10"
3) Product of Example 43 4) Cured 2 hr. at 100C, 1 hr. at 130C, 3 hr. at 150C.

EXAMPLES 47 to 56 The following Examples show the resins containing the additives in accordance with the instant invention are unexpectedly resistant to thermal shock. Resins prepared in Examples 44 to 46 were tested for thermal shock resistance.
Approximately 50 g samples were utilized to encapsulate washers as in Examples 6 to 15. The results are shown in Table XI below.

TABLE XI
15 Number of samples cracked during cycles1) 47 48 49 50 51 52 53 54 55 56 Formulations Example 44 6 1 32) _ _ _ _ _ _ _ Example 454 3 0 0 0 0 0 0 0 0 Example 463 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) All 10 samples were cracked after cycle 3.

In this Example, a polyether bis(benzamide) additive was prepared. Using the equipment and procedures of Example 43, 1330 g (.696 moles) of l'JEFFAMINE~ D-2000", 170 g of benzoic acid (1.393 moles) and 50 ml of ben2ene were charged to a 30 suitable reaction vessel. The resultant mixture was flushed `

.

~` . . . -with nitrogen and stirred under a nitrogen pad at reflux temperature (156 - 240C) with continuous water removal (85% of theoretical). A vacuum was slowly applied over about one hour to facilitate the removal of the remainder of the water. The admixture 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.

In this Example, the unexpected selectivity of the additive of the instant invention is demonstrated. Using the bis(benzamide) prepared in Example 57 as the additive, an anhydride cured formulation was prepared as shown in Table XII.
TABLE XII
Formulation Example Epoxy resin (Eg. 190) 100 Curing agent, pbwl) 85 20 Additive, pbw2) 20 Accelerator3) 2.5 Appearance of casting after cure4) Clear 1) "Nadic Methyl Anhydride~"
2) Product of Example 57 3) "DMP0-10"
4) Cured 3 hr. at 125C.
The clear appearance of the casting after cure indicates the absence of the improved properties obtained using the bis(formamide) additive in accordance with the present invention.
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Claims (10)

SET A
The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. A curable epoxy resin composition which comprises:
(i) a vicinal polyepoxide having an epoxide equivalent of greater than 1.8;
(ii) a curing amount of a substituted bicyclic vicinal anhydride curing agent; and (iii) an effective amount of an additive comprising a polyether diureide or diamide having terminal ureido or amido groups and a molecular weight of from 2000 to 3000.

2. A composition as claimed in Claim 1 which comprises an effective amount of a curing accelerator.

3. A composition as claimed in Claim 2 wherein the curing accelerator is a dialkyl amine substituted aromatic compound.

4. A composition as claimed in Claim 3 wherein the dialkylamine substituted aromatic compound is a dimethyl-aminomethyl substituted phenol.

5. A composition as claimed in Claim 1 wherein the diureide or diamide has the formula in which R is H or -NH2;
X is hydrogen, methyl or ethyl;
Z is alkylene having 2 to 5 carbon atoms, and n is a number such that the molecule of the above formula has a molecular weight of from 2000 to 3000.

6. A composition as claimed in Claim 5 wherein R
is NH2; X is methyl; Z is 1,2-propylene and n is an average number from 16 to 19.

7. A composition as claimed in Claim 5 wherein R
is H; X is methyl; Z is 1,2-propylene; and n is an average number from 16 to 19.

8. A method as claimed in Claim 1 wherein the vicinal polyoxide comprises at least 80% by weight of a polyglycidyl ether of a polyhydric phenols.

9. A composition as claimed in Claim l wherein the curing agent is methyl-bicyclo [2,2,1] heptene-2,3-di-carboxylic anhydride.

10. A composition as in Claim 1 which comprises:
(i) 100 parts by weight of the vicinal polyepoxide;
(ii) from 80 to 90 parts by weight of the curing agent;
(iii) from 5 to 35 parts by weight of the polyether diureide or diamide additive; and (iv) from 1 to 5 parts by weight of the curing accelerator.