Heat curable cationically polymerizable compositions and method of curing same with onium salts and reducing agents

Heat curable cationically polymerizable organic materials, such as epoxy resins, are described based on the use of an aromatic onium salt initiator which can be used in combination with a reducing agent. The heat curable compositions can be used in a variety of applications, such as coating compounds, photoresists, etc.

The present invention relates to heat curable cationically polymerizable 
organic materials, such as an epoxy resin, cyclic ether, 
phenol-formaldehyde resin, epoxy siloxane, etc., which use an aromatic 
onium salt initiator, such as an aromatic halonium salt, or a Group Va or 
Group VIa onium salt in further combination with a reducing agent. 
The term "reducing agent" as used hereinafter is a compound, or polymer 
having a molecular weight in the range of from about 80 to about 2000 and 
consisting of at least two or more chemically combined atoms selected from 
the class consisting of C, H, O, S, Si, halogen atoms, transition metals 
and metals selected from Groups III, IV, V, and VI metals, which reducing 
agents are capable of lowering, or reducing the charge of the hetero atom 
of an aromatic onium salt initiator selected from aromatic halonium salts, 
aromatic Group Va onium salts and aromatic Group VIa onium salts. 
The heat curable compositions of the present invention comprise (A) a 
cationically polymerizable organic material, (B) from 0.5% to 25% by 
weight of (A) of a reducing agent and (C) from 0.1% to 15% by weight of 
the heat curable composition of an aromatic onium salt selected from the 
class consisting of aromatic halonium salts, Group Va onium salts and 
Group VIa onium salts. 
As shown by my copending applications Ser. Nos. 638,982, now U.S. Pat. No. 
4,058,401, 638,983 and 638,994, now U.S. Pat. No. 4,069,055, assigned to 
the same assignee as the present invention, aromatic onium salts can be 
employed as photoinitiators to effect the cure of an epoxy resin. It was 
disclosed in the aforementioned copending applications that epoxy resins 
also can be heat cured without the use of radiant energy if desired. 
However, the heat cure of the epoxy resin employing the aforedescribed 
aromatic onium salts was considerably slower than by using a source of 
radiant energy, such as ultraviolet light. It has now been discovered that 
considerably faster heat cures of epoxy resins as well as a wide variety 
of other cationically polymerizable organic materials can be obtained 
using aromatic onium salts if the aromatic onium salt is used in 
combination with a reducing agent. 
The aromatic onium salts as used in the practice of the present invention, 
are included within the formula, 
EQU [Y].sup.+ [J].sup.-, (1) 
where J is a non-nucleophilic counterion defined more particularly below, 
and Y is a cation selected from the class consisting of an aromatic 
halonium cation, 
EQU [(R).sub.a (R.sup.1).sub.b D], (2) 
an aromatic Group Va cation, 
EQU [(R).sub.f (R.sup.2).sub.g (R.sup.3).sub.h E], (3) 
and an aromatic Group VIa cation, 
EQU [(R).sub.j (R.sup.4).sub.k (R.sup.5).sub.m G], (4) 
where R is a monovalent aromatic organic radical, R.sup.1 is a divalent 
aromatic organic radical, R.sup.2 and R.sup.4 are monovalent organic 
aliphatic radicals selected from alkyl, cyclo alkyl and substituted alkyl, 
R.sup.3 and R.sup.5 are polyvalent organic radicals forming a heterocyclic 
or fused ring structure selected from aliphatic radicals and aromatic 
radicals with E or G, D is a halogen radical, such as I, E is a Group Va 
element selected from N, P, As, Sb and Bi, G is a Group VIa element 
selected from S, Se and Te, 
"a" is a whole number equal to 0 or 2, 
"b" is a whole number equal to 0 to 1 
and when a is 0, b is 1 and when b is 0 a is 2, 
"f" is a whole number equal to 0 to 4 inclusive, 
"g" is a whole number equal to 0 to 2 inclusive, 
"h" is a whole number equal to 0 to 2 inclusive, and the sum of "f"+"g"+"h" 
is a value equal to 4 or the combining valence of E, 
"j" is a whole number equal to 0 to 3 inclusive, 
"k" is a whole number equal to 0 to 2 inclusive, and 
"m" is a whole number equal to 0 or 1, where the sum of "j"+"k"+"m" is a 
value equal to 3 or the combining valence of G. 
Radicals included by R can be the same of different, aromatic carbocyclic 
or heterocyclic radicals having from 6 to 20 carbon atoms, which can be 
substituted with from 1 to 4 monovalent radicals selected from 
C.sub.(1-8) alkoxy, C.sub.(1-8) alkyl, nitro, chloro, etc., R is more 
particularly phenyl, chlorophenyl, nitrophenyl, methoxyphenyl, pyridyl, 
etc. Radicals included by R.sup.1 are divalent radicals, such as 
##STR1## 
R.sup.2 and R.sup.4 radicals include C.sub.(1-8) alkyl, such as methyl, 
ethyl, etc., substituted alkyl, such as --C.sub.2 H.sub.4 OCH.sub.3, 
--CH.sub.2 COOC.sub.2 H.sub.5, --CH.sub.2 COCH.sub.3, Q' is defined below, 
etc., R.sup.3 and R.sup.5 radicals include such structures as 
##STR2## 
where Q' is selected from O, (CH.sub.2).sub.n, N, R and S, n is an integer 
equal to 1-4 inclusive; Z is selected from --O--, --S-- and 
##STR3## 
and R' is selected from hydrogen, C.sub.(1-8) alkyl, C.sub.(6-13) aryl, 
etc. 
Non-nucleophilic counterions included by J of formula (1) are MQ.sub.d 
anions, where M is a metal or metalloid, Q is a halogen radical, and d is 
an integer such as 4-6 inclusive. In addition, J of formula (1), also can 
include non-nucleophilic counterions such as perchlorate, CF.sub.3 
SO.sub.3.sup.- and C.sub.6 H.sub.4 SO.sub.3.sup.-, etc. In instances where 
the cationically polymerizable material is a phenol-formaldehyde resin, or 
other formaldehyde condensation resin such as urea, etc., J. of formula 
(1) can be a halide counterion such as Cl.sup.-, Br.sup.-, F.sup.-, etc., 
as well as nitrate, phosphate, etc. 
Metal or metalloids included by M of the non-nucleophilic counterion, 
MQ.sub.d previously defined and included within J of formula (1) are 
transition metals such as Sb, Fe, Sn, Bi, Al, Ga, In, Ti, Zr, Sc, V, Cr, 
Mn, Cs, rare earth elements such as the lanthanides, for example, Cd, Pr, 
Nd, etc., actinides, such as Th, Pa, U, Np, etc., and metalloids such as 
B, P, As, etc. Complex anions included by MQ.sub.d are, for example, 
BF.sub.4.sup.-, PF.sub.6.sup.-, AsF.sub.6.sup.-, SbF.sub.6.sup.-, 
FeCl.sub.4.sup.-, SnCl.sub.6.sup.-, SbCl.sub.6.sup.-, BiCl.sub.5.sup.=, 
etc. 
Halonium salts included by formula (1) and having formula (2) cations are 
for example, 
##STR4## 
Group VA onium salts included by formula (1) and having formula (3) cations 
are for example, 
##STR5## 
Group VIa onium salts included by formula (1) and having formula (4) 
cations are, for example, 
##STR6## 
The term "epoxy resin" as utilized in the description of the curable 
compositions of the present invention, include any monomeric, dimeric or 
oligomeric or polymeric epoxy material containing one or a plurality of 
epoxy functional groups. For example, those resins which result from the 
reaction of bisphenol-A (4,4'-isoproylidenediphenol) and epichlorohydrin, 
or by the reaction of low molecular weight phenol-formaldehyde resins 
(Novolak resins) with epichlorohydrin, can be used alone or in combination 
with an epoxy containing compound as a reactive diluent. Such diluents as 
phenyl glycidyl ether, 4-vinylcyclohexene dioxide, limonene dioxide, 
1,2-cyclohexene oxide, glycidyl acrylate, glycidyl methacrylate, styrene 
oxide, allyl glycidyl ether, etc., may be added as viscosity modifying 
agents. In addition, flexibilizers can be used such as hydroxy terminated 
polyesters and in particular hydroxyl terminated polycaprolactones such as 
Niax Polyols manufactured by the Union Carbide Corporation. 
In addition, the range of these compounds can be extended to include 
polymeric materials containing terminal or pendant epoxy groups. Examples 
of these compounds are vinyl copolymers containing glycidyl acrylate or 
methacrylate as one of the comonomers. Other classes of epoxy containing 
polymers amenable to cure using the above catalysts are epoxy-siloxane 
resins, epoxy-polyurethanes and epoxy-polyesters. Such polymers usually 
have epoxy functional groups at the ends of their chains. Epoxy-siloxane 
resins and method for making are more particularly shown by E. P. 
Plueddemann and G. Fanger, J. Am. Chem. Soc. 80 632-5 (1959). As described 
in the literature, epoxy resins can also be modified in a number of 
standard ways such as reactions with amines, carboxylic acids, thiols, 
phenols, alcohols, etc., as shown in U.S. Pat. Nos. 2,935,488; 3,235,620; 
3,369,055; 3,379,653; 3,398,211; 3,403,199; 3,563,804; 3,567,797; 
3,677,995; etc. Further examples of epoxy resins which can be used are 
shown in the Encyclopedia of Polymer Science and Technology, Vol. 6, 1967, 
Interscience Publishers, New York pp. 209-271. 
Additional cationically polymerizable organic materials which can be used 
in the heat curable compositions are thermosetting formaldehyde resins, 
cyclic ethers, lactones, lactams, cyclic acetals, vinyl organic 
prepolymers, etc. 
Included by thermosetting organic condensation resins of formaldehyde which 
can be used in the practice of the present invention are, for example, 
urea type resins, such as 
[CH.sub.2 .dbd.N--CONH.sub.2 ].sub.x.H.sub.2 O, 
[CH.sub.2 .dbd.NCONH.sub.2 ].sub.x CH.sub.3 COOH, 
[CH.sub.2 .dbd.NCONHCH.sub.2 NHCONHCH.sub.2 OH].sub.x ; 
phenol-formaldehyde type resins, such as 
##STR7## 
where x and n are integers having a value of 1 or greater than 1; 
##STR8## 
In addition, there can be used melamine thiourea resins, melamine, or urea 
aldehyde resins, cresol-formaldehyde resins and combinations with other 
carboxy, hydroxyl, amino and mercapto containing resins, such as 
polyesters, alkyds and polysulfides. 
Some of the vinyl organic prepolymers which can be used to make the 
polymerizable compositions of the present invention are, for example, 
CH.sub.2 .dbd.CH--O--(CH.sub.2 --CH.sub.2 O).sub.n --CH.dbd.CH.sub.2, 
where n is a positive integer having a value up to about 1000 or higher; 
multi-functional vinyl ethers, such as 1,2,3-propane trivinyl ether, 
trimethylolpropane trivinylether, prepolymers having the formula, 
##STR9## 
low molecular weight polybutadiene having a viscosity of from 200 to 
10,000 centipoises at 25.degree. C., etc. Products resulting from the cure 
of such compositions can be used as printing inks and other applications 
typical of thermosetting resins. 
A further category of the organic materials which can be used to make the 
polymerizable compositions are cyclic ethers which are convertible to 
thermoplastics. Included by such cyclic ethers are, for example, oxetanes 
such as 3,3-bis-chloromethyloxetane alkoxyoxetanes as shown by Schroeter 
U.S. Pat. No. 3,673,216, assigned to the same assignee as the present 
invention; oxolanes such as tetrahydrofuran, oxepanes, oxygen containing 
spiro compounds, trioxane, dioxolane, etc. 
In addition to cyclic ethers there are also included cyclic esters such as 
.beta.-lactones, for example propiolactone, cyclic amines, such as 
1,3,3-trimethyl-azetidine and organosilicon cyclics, for example, 
materials included by the formula, 
##STR10## 
where R" can be the same or different monovalent organic radical such as 
methyl or phenyl and m is an integer equal to 3 to 8 inclusive. An example 
of an organosilicon cyclic is hexamethyl trisiloxane, octamethyl 
tetrasiloxane, etc. The products made in accordance with the present 
invention are high molecular weight oils and gums. 
Included by the reducing agents which can be used in combination with the 
aromatic onium salts of the present invention, are for example, 
thiophenols, reducing sugars, ascorbic acid, citric acid, iron salts, such 
as (C.sub.5 H.sub.5).sub.2 Fe, (C.sub.7 H.sub.15 CO.sub.2).sub.2 Fe, etc., 
cobalt salts, such as (C.sub.7 H.sub.15 CO.sub.2).sub.2 Co, Co.sub.2 
(CO).sub.6 [(C.sub.6 H.sub.5).sub.3 P].sub.2, etc., in addition to iron 
and cobalt salts, there also can be used tin salts, such as (C.sub.7 
H.sub.15 CO.sub.2).sub.2 Sn, 
##STR11## 
and copper (I) salts, such as CuI, CuBr and CuCl, etc. 
The heat curable compositions of the present invention can be made by 
blending the cationically polymerizable organic material with an effective 
amount of the aromatic onium salt and in further combination with the 
reducing agent. In instances where the cationically polymerizable organic 
material is an epoxy resin, cyclic ether, cyclic ester and the like, as 
previously defined, the aromatic onium salt used is shown by formula (1), 
where J is an MQ.sub.d anion or CF.sub.3 SO.sub.3.sup.- and C.sub.6 
H.sub.4 SO.sub.3.sup.-. However, in instances where the cationically 
polymerizable material is a formaldehyde condensation resin as previously 
defined, J can also be halide, etc., as previously described. The 
resulting curable compositions can be in the form of a varnish having a 
viscosity of from 1 centipoise to 100,000 centipoises at 25.degree. C., or 
a free flowing powder. The curable compositions can be applied to a 
variety of substrates by conventional means and cured to the tack-free 
state within from 0.5 to 20 minutes, depending upon the temperature 
employed, which can vary from 25.degree. C. to 250.degree. C. 
Depending upon the compatibility of the onium salts with the epoxy resin as 
well as the reducing agent, the onium salts can be dissolved or dispersed 
along with the reducing agent into an organic solvent, such as 
nitromethane, acetonitrile, etc., prior to incorporation. In instances 
where the epoxy resin is a solid, incorporation of the onium salts can be 
achieved by dry milling or by melt mixing. 
Formation of the onium salt in situ also can be achieved if desired. 
Experience has shown that the proportion of onium salt to epoxy resin can 
vary widely inasmuch as the salt is substantially inert, unless activated. 
Effective results can be achieved if a proportion of from 1% to 15% by 
weight of onium salt is employed, based on the weight of curable 
composition. 
The curable compositions may contain inactive ingredients, such as 
inorganic fillers, dyes, pigments, extenders, viscosity control agents, 
process aids, UV-screens, etc., in amounts of up to 100 parts of filler 
per 100 parts of epoxy resin. The curable compositions can be applied to 
such substrates as metal, rubber, plastic, molded parts or films, paper, 
wood, glass cloth, concrete, ceramic, etc. 
Some of the applications in which the curable compositions of the present 
invention can be used are, for example, protective, decorative and 
insulating coatings, potting compounds, printing inks, sealants, 
adhesives, molding compounds, wire insulation, textile coatings, 
laminates, impregnated tapes, varnishes, etc. 
In order that those skilled in the art will be better able to practice the 
invention, the following examples are given by way of illustration and not 
by way of limitation. All parts are by weight.

EXMPLE 1 
A mixture of 3% by weight of tetramethylenephenacyl sulfonium 
hexafluoroarsenate and 97% by weight of Epon 828, a diglycidyl ether of 
bisphenol-A of Shell Chemical Company, were heated in a vial to 
150.degree. C. After 20 minutes of heating, there was no evidence of 
gelation. 
The above procedure was repeated, except that the mixture contained, in 
addition to the above-mentioned ingredients, 3% by weight of 
pentachlorothiophenol. It was found that a cured tack-free product was 
obtained by heating the mixture for 5 minutes at 150.degree. C. Those 
skilled in the art know that the aforementioned curable mixture would be 
suitable for encapsulating electronic components. 
EXAMPLE 2 
A uniform mixture of 3 parts of tetramethylenephenacyl sulfonium 
hexafluoroantimonate and 7 parts of Epon 828 was found to convert to the 
solid tack-free state after being heated in a vial at 150.degree. C. for 
15 minutes. Another sample of the same mixture was blended with 3 parts of 
pentachlorothiophenol per 100 parts of mixture. It was found that cure of 
the resulting mixture to a tack-free state was achieved in 2.5 minutes at 
150.degree. C. 
EXAMPLE 3 
A blend of 97 parts of Epon 828 and 3 parts of tetramethylenephenyacyl 
sulfonium hexalfuoroantimonate was blended with 3 parts of thiophenol. It 
was found that a tack-free cure was obtained after 5 minutes at 
150.degree. C. Another blend was made following the same procedure, except 
that thiosalicylic acid was substituted for the thiophenol. A similar cure 
of the mixture was achieved after 3 minutes at 150.degree. C. 
EXAMPLE 4 
A mixture of 3 parts of tetramethylenephenacyl sulfonium 
hexafluoroantimonate and 97 parts of Ciba Geigy cycloaliphatic bis epoxy 
CY-179 was heated at 150.degree. C. It was found that after 3 minutes, a 
cure of the mixture was obtained at 150.degree. C. 
EXAMPLE 5 
A blend of 97 parts of Epon 828 and 3 parts of diphenyliodonium 
hexafluoroarsenate was stirred in a vial and thereafter heated at 
120.degree. C. for 30 minutes. It was found that no significant change in 
the mixture occurred. 
The above procedure was repeated, except that 3 parts of 
pentachlorothiophenol was blended with the same mixture. It was found that 
a tack-free product was obtained in a vial after 4 minutes at 120.degree. 
C. 
EXAMPLE 6 
A blend of 97 parts of Ciba Geigy 179 and 3 parts of 
phenacyltriphenylphosphonium hexachloroantimonate was heated in a glass 
vial at 130.degree. C. It was found that after 30 minutes, no significant 
change in the mixture occurred. 
The above procedure was repeated, except that 3 parts of 
pentachlorothiophenol was added to the mixture. It was found that a 
tack-free product was obtained after 5 minutes at 130.degree. C. 
EXAMPLES 7-9 
To separate 10 ml samples of Ciba Giegy bisepoxide CY-179 there was added 
0.3 g 4,4'-dimethyldiphenyliodonium hexafluoroarsenate and 0.3 g of 
ferrocene, triron dodecacarbonyl and n-octylferrocene. These mixtures were 
heated in vials in an oil bath and the times requires for cure were 
recorded. 
______________________________________ 
Compound Cure Time 
______________________________________ 
None 4 hours 
7. ferrocene 6-7 min. 
8. triiron dodecacarbonyl 
3 min. 
9. n-octylferrocene 7 min. 
______________________________________ 
In a separate experiment, when CY-179 was heated at 120.degree. C. in the 
presence of ferrocene alone in the absence of the iodonium salt, cure 
failed to occur even after heating for 16 hours. 
EXAMPLE 10-13 
The previous experiment was repeated with the exception that the iron 
reducing agents were replaced with the following cobalt containing 
compounds: 
______________________________________ 
Compound Cure Time 
______________________________________ 
10. None 4 hours 
11. Co.sub.2 (CO).sub.6 [(C.sub.6 H.sub.5).sub.3 P].sub.2 
2 min. 
12. Co.sub.2 (CO).sub.6 [(C.sub.6 H.sub.5).sub.2 P--CH.sub.3 C.sub.6 
H.sub.4 ].sub.2 4 min. 
13. (C.sub.7 H.sub.15 CO.sub.2).sub.2 Co 
7. min. 
______________________________________ 
EXAMPLE 14 
A mixture composed of 3% by weight 4,4-dimethyldiphenyliodonium 
hexafluoroarsenate, 3% by weight stannous octoate and 94% CY-179 was 
heated at 130.degree. C. Cure occurred within 3 minutes. In the absence of 
stannous octoate, heating for 3 hours at 130.degree. C. was required to 
produce curing. 
EXAMPLE 15 
A mixture of 3% by weight or 4,4'-dimethyldiphenyliodonium 
hexafluoroarsenate and 97% of bisphenol-A type resin (Ciba Geigy Araldite 
6060) was heated at 170.degree. C. At this temperature, one hour was 
required to cure this formulation. Incorporation of 3% stannous octoate 
into this mixture, resulted in a decrease in the cure time to 4.3 minutes. 
EXAMPLE 16 
A blend composed of 76% Ciba Giegy Araldite 6060, 2% diphenyliodonium 
hexafluoroarsenate, 2% stannous octoate and 20% chopped glass fiber was 
blended together at 100.degree. C. This mixture was placed in a heated 
mold at 170.degree. C. for four minutes. A white molded bar was obtained 
which had good mechanical properties and excellent solvent resistance. 
EXAMPLE 17 
To a mixture composed of 3% 4,4'-dimethyldiphenyliodonium 
hexafluoroarsenate and 91% CY-179 was added 6% ascorbic acid. At 
130.degree. C., the above composition cures in two and one-half minutes. 
Addition of 6% ascorbic acid to CY-179 alone does not cause this bisepoxide 
to cure even when heated at 130.degree. C. for over 1 hour. 
EXAMPLE 18 
A mixture of 0.5 g 4,4'-dimethyldiphenyliodonium hexafluoroarsenate and 40 
g Shell bisphenol-A solid epoxy resin, Epon 1002, 1 g ascorbic acid and 15 
g chopped glass fiber were mixed together in a Brabender Torque Rheometer 
at 90.degree. C. A portion of this molding compound was pressed between 
heated metal plates at 165.degree.-170.degree. C. for 3 minutes. A flat 
molded film was obtained which had excellent solvent resistance in 
hydrocarbon solvents. 
EXAMPLE 19 
To a simple 3.24% solution of 4,4'-di-t-butyldiphenyliodonium 
hexafluorophosphate in CY-179 there was added various amounts of 
ferrocene. The samples were then heated in glass vials at 130.degree. C. 
and the time required to cure the mixture was recorded. 
______________________________________ 
% Ferrocene Cure Time 
______________________________________ 
18 210 seconds 
15 240 seconds 
12 275 seconds 
9 570 seconds 
______________________________________ 
EXAMPLE 20 
A mixture of 3% di-t-butyldiphenyliodonium hexafluoroantimonate and 6% 
ferrocene in CY-179 cured in 2.75 minutes at 120.degree. C. 
By way of contrast, 3% by weight BF.sub.3 -monoethylamine in CY-179 
requires 30 minutes of heating at 120.degree. C. to bring it to the same 
state of cure. The above example shows the advantage of using the cationic 
system of the present invention over Lewis acid catalysts. 
EXAMPLE 21 
A solution containing 3% 4,4'-dimethyldiphenyliodonium hexafluoroarsenate 
and 6% ferrocene in CY-179 was stored in the for seven weeks. The solution 
did not gel or undergo a change in viscosity during this time. 
In a similar study, a 3% solution of BF.sub.3 -monoethylamine in CY-179 
gelled within three days. The above example shows the high degree of 
pot-life stability obtainable in the cationic system of this invention 
compared with the rather poor pot-life of Lewis acid-epoxy mixtures. 
EXAMPLE 22 
A solution composed of 3% by weight 4,4'-dimethyldiphenyliodonium 
hexafluoroarsenate in bisphenol-A-diglycidyl ether (Sheel Co. Epon 828) 
was divided into 10 samples. To each of the samples was added different 
amounts of ferrocene. The aliquots were then heated in glass vials and the 
time required for cure was measured on heating at 130.degree. C. 
______________________________________ 
Cure Time 
% Ferrocene (seconds) 
______________________________________ 
21 66 
18 65 
15 75 
10 75 
9 85 
6 95 
4 135 
3 210 
2 220 
1 435 
0 &gt;144,000 
______________________________________ 
EXAMPLE 23 
A mixture of Ciba Geigy bisphenol-A solid epoxy resin containing 1.5% by 
weight diphenyliodonium hexafluoroarsenate and 3% ascorbic acid was placed 
in the mixing bowl of a brabender mixer at 90.degree. C. Both the torque 
and temperature were continuously monitored as an indication of cure. 
After 45 minutes, no change in the viscosity or temperature had occurred. 
At this point the temperature was raised rapidly to 170.degree. C. Cure 
occurred within 6 minutes after the rise in temperature was begun as 
indicated by the rapid increase in both torque and temperature. The resin 
produced was a solid highly crosslinked material which could not be 
further melted. 
When the same mixture of ingredients were placed in the mixing bowl of a 
brabender mixer at 170, cure occured in 45 seconds. 
The above two experiments show a unique feature of the redox cationic 
systems of this invention to be melted and handled at temperatures as high 
as 90.degree. C. for extended periods and then subsequently to cure 
rapidly when heated to elevated temperatures. 
EXAMPLE 24 
A mixture composed of 3% 4,4'-dimethyldiphenyliodonium hexafluoroarsenate, 
3% cuprous bromide and 94% CY-179 was heated at 120.degree. C. in an 
aluminum cup. The mixture cured to a hard nonfusible mass in 10-12 
minutes. 
EXAMPLE 25 
There were added 2 parts of diphenyliodonium hexafluoroarsenate and 2 parts 
ferrocene to 46 parts diethylene glycol divinyl ether. The mixture was 
poured into an aluminum cup and heated to 100.degree. C. A very rapid 
exothermic polymerization took place with the formation of crosslinked, 
hard resin. 
EXAMPLE 26 
There were added two parts diphenyldiodonium perchlorate and 3 parts 
ferrocene to 95 parts of a phenol-formaldehyde resin (Methylon 11 of the 
General Electric Company). The reaction mixture was heated to 120.degree. 
C. in an aluminum cup. The resin gelled to a hard crosslinked mass after 5 
minutes. 
EXAMPLE 27 
There were added 0.3 part of diphenyliodonium hexafluorophosphate and 0.3 
part of cuprous bromide to 10 parts of .epsilon.-caprolactone and the 
resulting mixture was thoroughly stirred. The mixture was then heated to 
100.degree. C. for 15 minutes and it was found to change from a viscous 
stirrable mixture to a hard tack-free solid. Based on method of 
preparation, the solid was polycaprolactone. 
EXAMPLE 28 
There were added 0.3 part of pentamethylene 
phenacylsulfoniumhexafluoroarsenate and 0.2 part of pentachlorothiophenol 
to 10 parts of .epsilon.-caprolactone. After the mixture was thoroughly 
stirred, it was heated at 100.degree. C. for 15 minutes. There was 
obtained a solid which on precipitation into methanol resulted in solid 
polycaprolactone. 
EXAMPLE 29 
A mixture of 20 parts of a phenolic based resol, Methylon 75201, a product 
of the General Electric Company, 0.3 part of 
diphenyliodoniumhexafluoroarsenate, and 0.2 part of cuprous bromide was 
poured into a shallow aluminum cup. The mixture was heated in a forced air 
oven at 100.degree. C. for 15 minutes. There was obtained a cross-linked, 
hard tack-free product. 
EXAMPLE 30 
A mixture of 10 parts of a urea-formaldehyde resin, Beetle 65, a product of 
the American Cyanamide Company, 0.15 part of 
diphenyliodoniumhexafluoroarsenate and 0.3 part of t-butylferrocene were 
placed in a screw cap vial and heated in a forced air oven at 110.degree. 
C. After one hour the mixture was converted from the pourable state to a 
hard cross-linked polymer. 
EXAMPLE 31 
There were added to 100 parts of a silicone gum consisting essentially of 
chemically combined dimethylsiloxy units and methylsiloxy glycidyl 
propionate units and terminated with dimethylsiloxy glycidyl propionate 
units, 3 parts of diphenyliodoniumhexafluoroarsenate and 3 parts of 
t-butylferrocene. The mixture was stirred and then heated for 5 minutes at 
120.degree. C. There was obtained an elastomeric hard rubber useful as an 
insulating compound and an encapsulant. 
Although the above examples are directed to only a few of the very many 
variables which can be used in the compositions of the present invention, 
it should be understood that the heat curable compositions of the present 
invention are directed to a much broader variety of materials comprising 
the aromatic onium salts of formula (1) in combination with the 
cationically polymerizable organic material and the reducing agent as 
shown in the description proceding these examples.