Note: Descriptions are shown in the official language in which they were submitted.
. ~
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.
~ - 2 -
.
. .- . . : . . , ., ~ ,, , . -
-` lJl'l~S
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.
.
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.
- 3 -
-. . ,:. :. :
.
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
'
, ~ ' : '
9S
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.
- 5 -
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
-- 6 --
X
-:
- . .
" . ~ . . .. . ..
~J.l~$~S
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
- 8 -
- : - ~ --: - '.-, -
.. - .. , ., .. . - . -: . .. - -: ~
~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~.
~ . .
.
_ g _
. ~:
:, ~, . - ~. . . . .
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.
. ~ , . . ............................................ .
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 -- , " ,. . .
. .
.. . . . :. ,, .................. , . . :. .
- .' .' ' : .' . ~.. ' '.' ' -
..
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
.
,
:
.... . .. -: . . - . : : . . :,
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.
~ ,
- 12 -
i . . . . ,: - , .
.. .. . . . . .
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
3
,
.
- 13 -
.: - . . . :
:- - : -
-
~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
- 14 -
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
- 15 -
~5
EXAMPLE 1
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.
EXAMPLE 2
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.
- 16 -
B
,
S
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.
EXAMPLES 3 T0 5
~ 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.
30 ~ ~
::
- 17 -
: ::: .
- . . .
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.
- 18 -
-. .. . . . , . .,: , . , . - ..
. . . . . : . . . . . .
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) -
B 2 1 2 1 0 0 1 0 1 0
C 0 0 2 1 0 0 0 0 0 0
D 0 0 1 0 0 0 0 0 2
E 0 0 0 0 1 0 0 0 0 0
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 -~
- 20 -
. .
~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
- 21 -
. . .
. ' ' :- . ...
- ' : ' ' ' - ~ ' ~ '. , '
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.
- 22 -
,
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
A 6 2 0 0 0 1 0 0 0 0
B 0 5 1 1 0 0 0 1 0 0
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.
EXAMPLE 42
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.
- 23 -
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.,: ' ' , . ' :
' ~ - . . . - :
.
,S
TABLE IX
Formulation Example -
42
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.
EXAMPLE 43
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.
- 24 -
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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
- 25 -
. . .
.
.
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.
EXAMPLE 57
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 `
- 26 -
.
~` . . . -
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.
EXAMPLE 58
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.
: ~',,,
- 27 -
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