This invention relates to C.sub.14 to C.sub.20 alkoxy monophenyl sulfonium salt initiators having the formula ##STR1## wherein R is C.sub.14 to C.sub.20 alkyl; R.sub.1 and R.sub.2 are each independently C.sub.4 to C.sub.20 alkyl and X.sup.- is a non-basic, nonnucleophilic anion, which initiators are employed in the polymerization of mono- and poly- functional glycidyl ethers, alpha-olefin oxides and vinyl monomers or oligomers.

In one aspect this invention relates to certain cationic initiators which 
have markedly improved solubility in hydrocarbons and ethers. 
In another aspect, the invention relates to a cationic polymerization 
initiator which is prepared by a simple process and to the use of these 
certain cationic initiators in the polymerization of alpha-olefins, 
epoxides and other monomers or oligomers containing long chain hydrocarbon 
groups. 
BACKGROUND OF THE INVENTION 
Photoinitiated cationic polymerization has received considerable attention 
in recent years as way to prepare 100% reactive coatings, inks, and 
adhesives. Accordingly, various cationic initiators have been developed, 
many of which are based on sulfonium and iodonium organic salts. However, 
most iodonium organic salts have been found to be unstable in the presence 
of highly reactive monomers. Of the sulfonium salts, those found to be 
useful include the triaryl sulfonium salts described in U.S. Pat. No. 
4,374,066, dialkyl phenacyl sulfonium salts described in U.S. Pat. Nos. 
4,058,401 and dialkyl hydroxyaryl sulfonium salts described in U.S. Pat. 
No. 4,230,814. Although useful for initiating the polymerization of a 
number of cationically polymerizable resins including epoxides, cyclic 
ethers and vinyl ethers, these highly polar, crystalline initiators are 
not readily soluble in non-polar solvents. Therefore, they are unsuitable 
for initiating the polymerization of long chain resins such as long chain 
alpha-olefin oxides and alkyl vinyl ethers. 
Recently, the preparation and use of triphenyl alkoxy sulfonium salt 
photoinitiators has been described in U.S. Pat. No. 4,882,201. Since it is 
now determined that hydrocarbon solubility improves with increasing length 
of an alkoxy chain group, these salts may be more suitable for initiating 
the cationic polymerizations of non-polar monomers and oligomers; however, 
increasing the alkyl chain length also increases crystallinity as 
indicated by a correspondingly increasing melting point. Hence, it is 
found that patentees' photoinitiators with long alkoxy chains must be 
heated to relatively high temperatures in order to effect their 
dissolution; thus, they are unsuitable for formulations involving volatile 
resins. A further drawback is that, since these initiators are only 
soluble in hydrocarbon resins at elevated temperatures, they tend to 
recrystallize out of solution at room temperature. The multicyclic alkaryl 
sulfonium salts of U.S. Pat. No. 4,319,974 also have been disclosed as 
cationic initiators; however, these display the same inability to remain 
in solution and recrystallize at or about room temperature. 
Accordingly, it is an object of this invention to provide a cationic 
initiator having markedly improved solubility in long chain hydrocarbons 
or hydrocarbon ethers at room temperature. 
Another object is to provide a cationic initiator which does not 
crystallize from a coating formulation at room temperature and which is 
effectively employed in a polymerization system involving hydrocarbon or 
volatile resins. 
Another object is to provide a process for curing alpha-olefin and glycidyl 
ether monomers or oligomers under mild conditions which is both economical 
and convenient. 
These and other objects of the invention will become apparent from the 
following description and disclosure. 
THE INVENTION 
The present invention is based on the discovery that certain dialkyl 
monoalkoxy phenyl sulfonium salts are unexpectedly and substantially more 
soluble in hydrocarbon resins than their corresponding polyphenyl alkoxy 
analogs and, unlike the latter, do not crystallize from coating 
formulations at room temperature. The cationic initiators of the present 
invention are described by the formula 
##STR2## 
wherein R is C.sub.14 to C.sub.20 alkyl; R.sub.1 and R.sub.2 are each 
independently C.sub.4 to C.sub.20 alkyl and X.sup.- is a non-basic, 
nonnucleophilic anion; examples of which include SbF.sub.6.sup.-, 
AsF.sub.6.sup.-, PF.sub.6.sup.-, BF.sub.4.sup.-, ClO.sub.4.sup.-, CF.sub.3 
SO.sub.3.sup.- and the like. 
Preferred examples of instant cationic initiators are antimony hexafluoride 
salts wherein R is a C.sub.14 to C.sub.18 alkyl and wherein R.sub.1 and 
R.sub.2 are each independently C.sub.4 to C.sub.12 alkyl or mixtures of 
said initiators. 
Examples of these initiators include 
##STR3## 
These UV photoinitiators include those which absorb in the mid and far 
ultraviolet ranges of the spectrum and can have their absorption 
capability extended by incorporating known photosensitizers as taught in 
Crivello and Lam, Journal of Polymer Science, 17, 1059 (1979). 
The present initiators are employed with monomers or oligomers of mono- or 
poly- functional glycidyl ethers, alpha-olefin oxides or vinyl compounds 
in a concentration of from about 0.1 to about 10 wt. %, preferably from 
about 0.3 to about 5 wt. %. 
The cationic photoinitiators of this invention are conveniently prepared in 
accordance with the following representative reactions 
##STR4## 
wherein n has a value of from 14 to 20; R.sub.1 and R.sub.2 are as defined 
above; M.sup.+ is a cation and X.sup.- is a non-basic, nonnucleophilic 
anion as identified. The above reactions are carried out at a temperature 
of between about 0.degree. and about 70.degree. C., preferably between 
about 20.degree. and about 35.degree. C. under atmospheric pressure with 
constant agitation over a period of from 1 to 24 hours in the presence of 
a solvent. Suitable solvents, in addition to methane sulfonic acid, 
include methylene chloride, carbon tetrachloride, and the like. 
The sulfonium salt product is then recovered in a substantially pure state 
by filtration, washing and purified further by recrystallization. 
The crystalline cationic photoinitiator can be then dissolved in the 
monomer or oligomer of choice, coated on a substrate of paper, glass, 
plastic or metal to a thickness of from about 0.5 to 5 mils, usually from 
about 0.8 to about 2 mils and then cured. 
The coating mixture is cured by exposure to radiation such as supplied by 
Uv light, ionizing radiation, laser radiation etc. at about room 
temperature until a tack-free film is obtained. 
Suitable monomers or oligomers which are curable with the present 
initiators include vinyl anisole, styrene, lauryl vinyl ether, cetyl vinyl 
ether, octadecyl vinyl ether, cyclohexane dimethanol divinyl ether, 
bisphenol-A diglycidyl ether, cyclohexeneoxide, butyl glycidyl ether, 
styrene oxide, phenyl glycidyl ether. The mention of these monomers does 
not mean to imply that other radiation curable monomers or oligomers 
cannot be similarly cured using the present initiators, but only that 
these other monomers do not present the difficulties associated with those 
above. Such other monomers include tri- or tetra- ethylene glycol divinyl 
ether, hydroxy butyl vinyl ether, tetrahydrofurfuryl vinyl ether, 
3,4-epoxycyclohexyl methyl-3',4'-epoxycyclohexane carboxylate. Of course 
it will be understood that mixtures of the above monomers or oligomers can 
be employed. 
The improved hydrocarbon solubility of the present initiators renders them 
suitable for preparing uv-curable non-silicone release coatings as 
described in the copending U.S. patent application by the same inventors 
entitled RAPIDLY CURABLE VINYL ETHER RELEASE COATINGS. Also, films of the 
present cured polymers can also be cast in sheets and used in packaging of 
comestible and other products or applied as protective coatings on various 
substrates. 
Having generally described the invention, reference is now made to the 
accompanying examples which illustrate preferred embodiments but which are 
not to be construed as limiting to the scope of the invention as more 
broadly described above and in the appended claims.

EXAMPLE 1 
A 1-liter three necked round bottom flask was charged with 100 grams (0.33 
moles) of 1-bromohexadecane, 92.5 grams (0.99 moles) of phenol, 55.2 grams 
(0.99 moles) of potassium hydroxide, 10 grams of tetra-n-butylammonium 
bromide, 167 ml of toluene, and 167 ml of water. The flask was fitted with 
a mechanical stirrer, nitrogen inlet, condenser, thermometer and heating 
mantle. The reaction mixture was heated to reflux at about 92.degree. C., 
under a nitrogen purge for 16 hours with constant agitation. After 16 
hours, the mixture was cooled and transferred to a separatory funnel where 
the aqueous layer was removed and the upper toluene layer was washed three 
times with 200 ml 0.5N NAOH and three times with 200 ml deionized water. 
The toluene was removed under reduced pressure leaving 102.6 grams (98% 
yield) of n-hexadecyl phenyl ether. Analysis by gas chromatography showed 
that the product was 98.3% pure. 
A 250 ml three necked flask equipped with a mechanical stirrer and dropping 
funnel was charged with 12.72 grams (0.04 moles) of n-hexadecyl phenyl 
ether, 15 grams of methylene chloride, and 20 ml of a 1:10 mixture of 
P.sub.2 O.sub.5 dissolved in methanesulfonic acid. A solution of 6.5 grams 
(0.04 moles) of n-butyl sulfoxide dissolved in 25 grams of methylene 
chloride was added dropwise with constant stirring while maintaining the 
reaction temperature below 25.degree. C. After 23 hours, the reaction 
mixture was poured into 200 ml deionized water and transferred to a 
separatory funnel where the aqueous layer was removed. The methylene 
chloride layer was mixed with 200 ml of acetone containing 10.36 grams 
(0.04 moles) NaSbF.sub.6. After 1 hour, the solution was filtered and the 
acetone was removed under reduced pressure. The crude product was 
recrystallized from methanol to give 15.9 grams (56.8% yield) of the 
sulfonium salt (mp=41.degree.-45.degree. C.) having the formula 
##STR5## 
The photoactivity of the above product was confirmed by dissolving 1% by 
weight in triethylene glycol divinyl ether. A 1 mil film was cast on a 
glass plate using a #12 Mayer bar and was exposed to UV light. A tack-free 
film was instantly produced with as little as 60 Mj/CM.sup.2 UV 
irradiation. 
EXAMPLE 2 
Example 1 is repeated except that an equivalent amount of the sodium salts 
of non-nucleophilic anions AsF.sub.6.sup.-, PF.sub.6.sup.-, 
BF.sub.4.sup.-, ClO.sub.4.sup.-, and CF.sub.3 SO.sub.3.sup.- were used in 
place of NaSbF.sub.6. The corresponding photoinitiators were recovered in 
good yield. Photoactivity was tested by dissolving 1% by weight of each 
product in 1.5 gm triethylene glycol divinyl ether. The resulting solution 
was placed in an aluminum weighing pan and exposed to 1000 mJ/cm.sup.2 UV 
irradiation. In each case a crosslinked polymer was formed immediately. 
EXAMPLE 3 
Example 1 is repeated except that an equivalent amount of 1-bromooctadecane 
is used in place of 1bromohexadecane. The corresponding crude product was 
recrystallized from methanol to give a 65% yield of the sulfonium salt 
(mp=57.degree.-60.degree. C.) having the formula 
##STR6## 
The photoactivity of the above product was confirmed by dissolving 1% by 
weight in triethylene glycol divinyl ether. A 1 mil film was case on glass 
using a #12 mayer bar and was exposed to UV light. A tack-free film was 
instantly produced with as little as 60 mJ/cm.sup.2 UV irradiation. 
EXAMPLE 4 
Example 3 is repeated except an equivalent amount of methyl sulfoxide is 
used in place of N-butyl sulfoxide. The following photoinitiator 
(mp=76.degree.-82.degree. C.) having the formula 
##STR7## 
was recovered. 
The photoactivity of the above product was confirmed by dissolving 1% by 
weight in triethylene glycol divinyl ether at 80.degree. C. A 1 mil film 
was immediately cast on glass using a #12 Mayer bar and was exposed to UV 
light. A tack-free film was produced instantly with as little as 60 
mJ/cm.sup.2 UV irradiation. 
EXAMPLE 5 
Example 4 is repeated except that an equivalent amount of decyl sulfoxide 
is used in place of the methyl sulfoxide. The resulting crude product was 
a viscous oil which was purified by washing with methanol to give the 
following photoinitiator 
##STR8## 
EXAMPLE 6 
The solubility of the above sulfonium hexafluoroantimonate salts were 
compared on an equivalent weight basis to the following previously 
developed photinitiators: 
##STR9## 
A release coating was prepared using the following formulae: 
0.38 equivalents dodecyl vinyl ether 
0.20 equivalents triethylene glycol divinyl ether 
5.8.times.10.sup.-4 equivalents photoinitiator 
Components were blended by warming the mixture to a temperature slightly 
above the melting point of the initiator in order to advance dissolution 
of the photoinitiator and then allowed the solution to cool to 25.degree. 
C. in a water bath. The compositions were observed after 4 hours for any 
photoinitiator precipitation. The results clearly demonstrate the 
unexpected and improved solubility of the dialkyl alkoxyphenyl sulfonium 
salts of this invention. 
______________________________________ 
PHOTOINITIATOR SOLUBILITY 
______________________________________ 
##STR10## no crystallization 
##STR11## no crystallization 
##STR12## recrystallization 
##STR13## no crystallization 
##STR14## recrystallization 
##STR15## recrystallization 
______________________________________ 
It will be understood that other initiators of this invention can be 
substituted for those in Examples 1, 2, 3 or 5 to achieve similar results 
and also that any of the other monomers or oligomers described above can 
be substituted in these Examples to provide tack-free coatings.