The invention relates to silicone-polyether linear block copolymers of the formula ##STR1## wherein, R is hydrogen or a C.sub.(1-8) alkyl, alkoxyl or haloalkyl radical or a monovalent epoxy-functional organic radical; PA1 R.sup.1 is hydrogen or a C.sub.(1-8) alkyl or alkoxyl radical, or a monovalent epoxy-functional organic radical; PA1 provided that at least two R or R.sup.1 groups are either hydrogen or monovalent epoxy-functional organic radicals; PA1 R.sup.2 is a divalent alkylene radical; PA1 R.sup.3 is a C.sub.(2-6) alkyl or alkoxyl radical; PA1 n is a positive integer of about 4 to about 400; PA1 m is a whole number of from 0 to about 50; and, each of R, R.sup.1, R.sup.2 and R.sup.3 may be unsubstituted or substituted. The invention also relates to UV-curable compositions comprising the above-described compound, with or without a UV-detectable dye marker, and a process for making such a compound.

BACKGROUND OF THE INVENTION 
The present invention relates to flexible, UV curable, 
epoxysilicone-polyether coatings which are obtained by the incorporation 
of polyether block segments into linear SiH-containing silicone backbones, 
which may be followed by conversion of the SiH-containing 
silicone-polyethers into their epoxy-containing linear block copolymer 
derivatives. The invention also relates to flexible, UV-curable 
epoxysilicone-polyether coating as described above and further 
incorporating one or more fluorescent dye markers. The product of the 
present invention is useful for a wide range of coating applications 
including release coatings, optical fiber buffer coatings, conformal 
coatings and electronic encapsulation, and when produced with 
UV-detectable dye marker, the product of the invention is particularly 
useful for ascertaining the integrity of very thin coatings. The invention 
further relates to a process for producing the above-mentioned 
epoxy-containing siliconepolyether linear block copolymers. 
Epoxysilicone polymers have been widely used in the release coating and 
pressure-sensitive adhesive (PSA) industries. For example, see generally 
the chapter entitled "Silicones" by B. Hardman and A. Torkelson in the 
Encyclopedia of Polymer Science and Engineering, 2nd edit., Vol. 15, pp. 
204-308, 1989, John Wiley & Sons, Inc., New York. Epoxysilicone polymers 
are conveniently manufactured through the hydrosilation reaction between 
an SiH-containing silicone monomer or polymer and olefin epoxides. The 
general hydrosilation reaction between a silicone and olefin can be 
expressed for monofunctional silane derivatives as 
EQU .tbd.SiH+CH.sub.2 .dbd.CH--Q.fwdarw..tbd.Si--CH.sub.2 --CH.sub.2 --Q 
and for di-functional siloxane derivatives as 
EQU --(--CH.sub.3 (H)SiO--)--+CH.sub.2 
.dbd.CH--Q.fwdarw.--(--(CH.sub.3)(QCH.sub.2 CH.sub.2)SiO--)-- 
where in both cases Q is an organic radical. The hydrosilation reaction is 
particularly useful for the addition of functional radicals onto silanes 
and silicones. For example, reaction of a hydrogensiloxane with an 
epoxy-containing olefin yields an epoxy-functional siloxane. 
Epoxysiloxanes generated through, for example, the hydrosilation reaction 
can be cured either thermally or, in the presence of the appropriate 
catalysts and possibly accelerators, by irradiation. Generally, 
UV-induced, cationic catalysi is preferred in the cure reaction of 
epoxysilicones due to the relatively low cost of this process, relatively 
high cure rates achieved, the low temperature which can be employed, 
thereby preventing damage to temperature-sensitive materials being coated, 
and the low risk of potential hazards to both industrial users and the 
environment. Upon exposure to UV radiation, cationic type photo-initiators 
generate a strong Bronsted acid, which effects the opening of the oxirane 
ring in the epoxide radical of an epoxysilicone polymer, and the 
subsequent etherification through which cross-linking of the resin is 
achieved. 
The curing of epoxysilicone polymers is well documented in the patent 
literature. For example, U.S. Pat. No. 4,576,999, issued to Eckberg, 
discloses epoxy and/or acrylic functional polysiloxanes as UV-curable 
abhesive release coatings. The catalyst may be a photo-initiating onium 
salt and/or a free radical photo-initiating catalyst. U.S. Pat. Nos. 
4,279,717 and 4,421,904, both issued to Eckberg, et al., disclose epoxy 
functional diorganosiloxane fluids combined with iodonium salts to form 
UV-curable abhesive release compositions. U.S. Pat. No. 4,547,431 
discloses epoxy functional diorganosiloxane combined with onium salt 
catalyst and polyfunctional epoxy monomers to also form an abhesive 
release coating. All patents and publications mentioned herein are 
incorporated by such reference. 
As described in U.S. Pat. No. 4,576,999, the preferred UV photo-initiators 
for the curing of epoxysilicones are the "onium" salts, of the general 
formulas 
EQU R.sub.2 I.sup.+ MX.sub.n.sup.- 
EQU R.sub.3 S.sup.+ MX.sub.n.sup.- 
EQU R.sub.3 Se.sup.+ MX.sub.n.sup.- 
EQU R.sub.4 P.sup.+ MX.sub.n.sup.- 
EQU R.sub.4 N.sup.+ MX.sub.n.sup.- 
where different radicals represented by R can be the same or different 
organic radicals from 1 to about 30 carbon atoms, including aromatic 
carbocyclic radicals from 6 to 20 carbon atoms which can be substituted 
with from 1 to 4 monovalent radicals selected from C.sub.(1-8) alkoxyl, 
C.sub.(1-8) alkyl, nitro, chloro, bromo, cyano, carboxy, mercapto, etc., 
and also including aromatic heterocyclic radicals including, for example, 
pyridyl, thiopheny, pyranyl, and others; and MX.sub.n.sup.- is a 
non-basic, non-nucleophilic anion, such as BF.sub.4.sup.-, PF.sub.6.sup.-, 
AsF.sub.6.sup.-, SbF.sub.6.sup.-, HSO.sub.4.sup.-, ClO.sub.4.sup.-, and 
others as known in the art. The photo-initiators may be mono- or 
multi-substituted mono, bis or tris aryl salts. In the above and 
subsequent definitions, the prefix "hetero" is meant to include linear or 
cyclic organic radicals having incorporated therein at least one 
non-carbon and non-hydrogen atom, and is not meant to be limited to the 
specific examples contained herein. According to U.S. Pat. No. 4,977,198, 
the onium salts are well known, particularly for use in catalyzing cure of 
epoxy functional materials. 
As disclosed in U.S. Pat. No. 4,882,201, the radiation-initiated cure of 
epoxysilicones coated on a substrate can be achieved with UV lamps such 
as: mercury arc lamps (high, medium and low pressure), Xenon arc lamps, 
high intensity halogentungsten arc lamps, microwave driven arc lamps and 
lasers. Additionally, ionizing radiation using, for example, .sup.60 Co is 
also useful as a radiation source. In this latter instance, the ionizing 
radiation serves both to initiate cure and at the same time sterilize an 
epoxysilicone coating. 
Certain polyether-silicone copolymers are known. For example, U.S. Pat. No. 
4,988,504 discloses polysiloxane polymers bearing pendant polyether 
radicals for use in stabilizing silicone emulsions. Similarly, Japanese 
Published Patent Application 02-129219 discloses use of epoxysilicones 
bearing radially pendant polyethers, described as having good 
compatibility with onium salt photoinitiators, for use as coatings which 
can be printed on. U.S. Pat. Nos. 4,758,646 and 4,859,529 disclose 
bis(alkoxysilyl)polyethers for use as a fabric sizing agent, and U.S. Pat. 
No. 4,184,004 describes organosilicone terpolymers bearing radially 
pendant polyethers as a fabric softening agent. In each of the 
above-mentioned patents, the polymer may be described as a "block" 
copolymer with respect to the silicone monomeric units. For example, 
compounds of the formula 
EQU --(--(CH.sub.3).sub.2 SiO).sub.x --(Q.sub.2 SiO).sub.n --((CH.sub.3).sub.2 
SiO--).sub.y -- 
wherein n, x and y are greater than 1 and the substituent Q (for example, a 
polyether) is in a radially pendent block, as opposed to randomly 
distributed, with respect to the (CH.sub.3).sub.2 SiO backbone. This 
molecular organization should be contrasted with that of a "linear block 
copolymer" of the general formula 
EQU --(--(CH.sub.3).sub.2 SiO).sub.x --(Q).sub.n --((CH.sub.3).sub.2 
SiO--).sub.y -- 
wherein n, x and y are greater than 1 and the substituent Q, again perhaps 
a polyether monomeric unit, is incorporated directly into a linear 
siloxane backbone. 
Dye sensitizers are also known as, for example, disclosed in the 
aforementioned U.S. Pat. No. 4,977,198. Dye sensitizers are cure 
accelerators which serve to increase the effectiveness of the 
photocatalyst by generally absorbing light that is of a wavelength outside 
the useful range of that of the photo-initiator and transferring the 
absorbed energy to the photo-initiator. Thus, the dye sensitizer results 
in better utilization of the energy available from a light source, with 
the result that this source need not be specifically tuned to match the 
main absorption wavelength of the photo-initiator. Dyes which are useful 
with the abovedescribed onium salts are cationic dyes, such as shown in 
Vol. 20, pages 194-197 of the Kirk-Othmer Encyclopedia, 2nd Edition, 1965, 
John Wiley & Sons, New York. Some of the cationic dyes which can be used 
as sensitizers include, for example, 
Acridine Orange; C.I. 46005; 
Acridine Yellow; C.I. 46035; 
Phosphine R; C.I. 46045; 
Benzoflavin; C.I. 46065; and, 
Setoflavin; C.I. 49005. 
In addition, some basic dyes can also be used as sensitizers Some of these 
basic dues are shown in Vol. 7, p.532-4 of Kirk-Othmer Encyclopedia, as 
cited above, and include: 
Hematoporphyrin; 
4,4'-bisdimethylaminobenzophenone; and, 
4,4'-bisdiethylaminobenzophenone. 
Also suitable are xanthones, such as thioxanthone, 2-isopropyl xanthone, 
and aminoxanthene. Specific instances where dye sensitizers are employed 
are detailed, for example, in U.S. Pat. No. 4,026,705. 
A major drawback to the use of the "onium" salt catalysts in the 
polymerization of epoxysilicones lies in the highly polar nature of these 
salts. As the commonly used silicones are based on non-polar 
polydimethylsiloxane polymers, the polar "onium" catalysts are not 
sufficiently miscible with the resin to affect as fast a cure rate as 
would generally be desirable nor are suspensions of the insoluble 
catalysts stable. The need therefore exists to devise novel materials and 
processes in which the miscibility of the photo-initiators and siloxanes 
are much improved. 
Two general approaches have been taken to increase the miscibility of an 
onium photo-initiators and an epoxysilicone resin. The first approach has 
been to increase the hydrophobicity of the catalyst through use of onium 
salts containing non-polar, organic radicals. This approach led to 
investigations of potential onium salts, particularly longchain 
alkyl-substituted bisaryliodonium salts, which are less polar in nature 
than their sulfonium counterparts. As disclosed in U.S. Pat. No. 
4,882,201, particularly useful catalysts of this type are the linear or 
branched, C.sub.8 or greater alkoxy, mono- or disubstituted, 
bisaryliodonium salts. As further disclosed in U.S. Pat. No. 4,882,201, 
the long-chain, alkoxy-substituted aryliodonium salts also possess the 
useful property of being much less toxic than the non-substituted onium 
salt photo-initiators. 
The second approach to alleviating the aforementioned miscibility problem 
between the photo-initiator and a silicone has been to incorporate 
silphenylene blocks into a siloxane backbone, for example as disclosed in 
U.S. Pat. No. 4,990,546. This approach, when coupled with the use of the 
above-described substituted onium salts, proved useful in increasing 
photo-initiated cure. However, the incorporation of silphenylene blocks 
into a silicone resin is not commercially viable, since the 
disilyl-functional benzenes needed to produce the silphenylene-containing 
polymers are not available in commercial quantities. 
In a more indirect effort to overcome the relatively slow cure rates due to 
the above-mentioned miscibility problem, an epoxysilicone resin is 
"pre-crosslinked" as disclosed, for example, in U.S. Pat. No. 4,987,158. 
While such "pre-crosslinked" epoxysilicone networks, formed from vinyl 
tetramer and SiH-containing linear silicones partially overcome some of 
the slow cure associated with long chain epoxysilicone coatings, these 
partially-cured resins still do not possess a solubility with iodonium 
catalysts that is sufficiently high to be commercially useful as 
UV-curable materials in most applications. 
Another problem typically encountered in the silicone coating industry, is 
that of the difficulty in assessing the sufficiency of very thin silicone 
coatings, particularly when these coatings are applied to shiny or glossy 
types of film liner. For example, in the release coating and electronics 
industry, if the coating on a substrate contains gaps wherein no silicone 
is present, there results a poor product performance and the subsequent 
economic waste associated therewith. It would be advantageous therefore to 
provide a system whereby the integrity of a silicone release coating could 
be easily and economically evaluated. In particular, it would be desirable 
to incorporate a colorless marker into a silicone resin, as this would 
still allow visually clear coatings to be produced. UV-detectable dye 
markers would be particularly preferable for such use. However, possibly 
in part due to the above-mentioned miscibility problems encountered with 
the use of non-polar silicone resins, such a system has heretofore not 
been available. 
Due to the above-mentioned considerations, it has therefore been desirable 
to search for novel ways in which to increase the miscibility of polar 
compounds, particularly photo-initiator salts, in epoxysilicone resins 
such that high and efficient cure rates can be economically achieved. In 
addition it would also be advantageous to, at the same time, provide for 
epoxysilicones that are more flexible and elastomeric than traditionally 
available, and thus have a greater number of potential uses than current 
resins. Finally, it would be particularly advantageous to, at still the 
same time, provide a system whereby the integrity of application of a 
silicone coating, particularly thin clear coatings, on glossy or shiny 
substrates can be easily monitored. 
One aim of the present invention is to alleviate the miscibility problems 
of onium salt catalysts with silicone resins, and thereby improve the cure 
characteristics of these resins. A second aim of the invention is to 
prepare more highly flexible and elastomeric silicone resins, also with 
faster cure rates than previously possible. Yet another aspect of the 
present invention is to devise a system for easily and accurately 
monitoring the integrity of a coating of these resins onto a substrate. A 
further aim of the present invention is to provide a process for preparing 
a resin with the above-mentioned characteristics. 
SUMMARY OF THE INVENTION 
The invention provides for resins composed of siliconepolyether block 
copolymers of the formula 
##STR2## 
wherein, R is hydrogen or a C.sub.(1-8) alkyl, alkoxyl, or haloalkyl 
radical, preferably trifluoropropyl, or a monovalent epoxyfunctional 
radical of from about 2 to about 20 carbons; 
R.sup.1 is hydrogen or a C.sub.(1-8) alkyl or alkoxyl radical, preferably a 
methyl radical, or a monovalent epoxy-functional organic radical of from 
about 2 to about 20 carbons; 
provided that at least two R or R.sup.1 groups are either hydrogens or 
monovalent epoxy-functional organic radicals; 
R.sup.2 is a C.sub.(1-6) divalent alkylene radical, preferably ethylene; 
R.sup.3 is a C.sub.(2-6) alkyl or alkoxyl radical, preferably an ethyl or 
propyl radical; 
n is a positive integer of about 4 to about 400; and, 
m is a whole number from 0 to about 50. 
Any or all of R, R.sup.1, R.sup.2, or R.sup.3 groups may be either linear 
or branched, and may be unsubstituted or substituted with functional 
groups such as halogen, hydroxy, cyano, amino, thio, mercapto, and the 
like. Additionally, each of the individual R, R.sup.1, R.sup.2, or 
R.sup.3, groups may be the same or different. 
The silicone polyether copolymer of the present invention is much more 
miscible with polar molecules, particularly iodonium salt photo-initiators 
and UV-detectable dyes, than non-polyether containing silicone resins The 
invention also provides for an epoxysilicone-polyether copolymer resin 
incorporating a UV-detectable organic dye, through which the pattern and 
efficiency of coating of the resin onto a substrate is easily and 
accurately monitored The invention further provides for a process of 
preparing and curing such silicone-polyether block copolymers.

DETAILED DESCRIPTION OF THE INVENTION 
In order to prepare epoxysilicone resins in which onium salt 
photo-initiators are miscible, it would be desirable to provide a resin 
that is compatible with the polar characteristic of onium salts. In the 
process and product of the present invention, an epoxysilicone resin is 
made more polar by the inclusion of linear blocks comprising a polyether 
into a siloxane backbone to generate a linear epoxysilicone-polyether 
block copolymer, compound (I), of the average formula 
##STR3## 
wherein, R is hydrogen or a C.sub.(1-8) alkyl, alkoxyl, or haloalkyl 
radical, preferably trifluoropropyl, or a monovalent epoxy-function 
radical of from about 2 to about 20 carbons; 
R.sup.1 is hydrogen or a C.sub.(1-8) alkyl or alkoxyl radical, preferably a 
methyl radical, or a monovalent epoxy-functional radical of from about 2 
to about 20 carbons; 
provided that at least two R or R.sup.1 groups are either hydrogens or 
monovalent epoxy-functional organic radicals; 
R.sup.2 is a C.sub.(1-6) divalent alkylene radical, preferably ethylene; 
R.sup.3 is a C.sub.(2-6) alkyl or alkoxyl radical, preferably an ethyl or 
propyl radical; 
n is a positive integer of about 4 to about 400 and, 
m is a whole number of 0 to about 50. 
Any or all of R.sup.1, R.sup.2, or R.sup.3 groups may be either linear or 
branched, and may be unsubstituted or substituted with functional groups 
such as halogen, hydroxy, cyano, amino, thio, mercapto, and the like 
Additionally, each of the individual R, R.sup.1, R.sup.2, or R.sup.3, 
groups may be the same or different. The formula of compound (I) is a 
number average formula, and the invention also incorporates linear 
silicone-polyether block copolymers in which compounds based on the 
formula of compound I are linked either in end-to-end or branched form, or 
both, to form longer copolymers that have a formula which is a multiple of 
that of compound (I). 
In general, the polyether block of compound I is derived from a diallyl 
derivative of a glycol, having the formula 
EQU CH.sub.2 .dbd.CHCH.sub.2 O(R.sup.3 O).sub.m CH.sub.2 CH.dbd.CH.sub.2(II) 
wherein R.sup.3 and m are defined as for compound (I), and each R.sup.3 
radical may be the same or may be different. Preferably, the R.sup.3 
groups in compound (II) are either ethyl or propyl radicals, and most 
preferably the polyether block is a diallyl derivative of tetraethylene 
glycol (TEGDAE) of the formula 
EQU CH.sub.2 .dbd.CHCH.sub.2 O(CH.sub.2 CH.sub.2 O).sub.4 CH.sub.2 
CH.dbd.CH.sub.2 (III) 
The incorporation of a polyether block into a polyorganosiloxane to produce 
the epoxysilicone-polyether linear block copolymers of the present 
invention is achieved through a two-step hydrosilation process. As 
discussed below, these reactions may be catalyzed either by conventional 
platinum catalysts as described in U.S. Pat. Nos. 3,220,927, 3,419,593 or 
3,775,452, or by rhodium catalysts as described in U.S. Pat. No. 
3,928,629. The first hydrosilation reaction is that between a molar excess 
of an SiH-containing linear silicone with a diallyl ether derivative of a 
glycol described above. The molar excess described is meant to mean a 
molar excess of reactive H in the silicone with respect to the number of 
double bonds in the diallyl ether. In such a case, after the first 
hydrosilation reaction there still exists unreacted SiH groups. In a 
preferred embodiment of the present process, at least 20% of the SiH 
initially present is unreacted after the first hydrosilation reaction, 
while in the most preferred process at least 40% of reactive SiH remains. 
The product of the first hydrosilation reaction generally has the formula 
of Compound (I), with the stipulation that a least two R or R.sup.1 groups 
are hydrogen. 
In the product and process of the invention, the SiH-containing linear 
silicone is preferably an SiH-stopped polydimethylsiloxane due to 
commercial availability. However, as other substituted organosiloxanes 
become commercially available in sufficient quantity, use of these 
materials would also be preferred in practicing the present invention, 
provided that these materials do not substantially alter the properties of 
the product of the invention described herein. 
The second step of the process of the invention is the reaction between the 
SiH-containing polysiloxane-polyether copolymer and an olefin epoxide, to 
generate an epoxysilicone-polyether linear block copolymer of the formula 
of Compound (I), with the stipulation that at least two R or R.sup.1 
groups are monovalent epoxy-functional organic radicals of from about 2 to 
about 20 carbons. Examples of suitable olefin epoxy compounds for use in 
the second hydrosilation reaction step in the process of the present 
invention include limoneneoxide, 4-vinylcyclohexeneoxide (VCHO), 
allylglycidylether, glycidylacrylate, 1-methyl-4-isopropenyl 
cyclohexeneoxide, 7-epoxy-1-octene, 2,6-dimethyl-2,3-epoxy-7-octene, 
vinylnorbornenemonoxide, dicyclopentadienemonoxide, and the like. 
Preferably the unsaturation in the olefin epoxides is terminally located 
on an alkyl chain, as such bonds have been found to be more reactive in 
the hydrosilation reaction. Most preferably, 4-vinylcyclohexene oxide is 
used as the olefin epoxide in the practice of the process of the 
invention. By "linear block copolymer" it is meant that the polyether 
blocks are incorporated into, and flanked by, an organosiloxane polymer 
chain in an end-to-end fashion, as opposed to an incorporation of a 
polyether block in a radially pendant fashion. 
The hydrosilation catalyst used in the process of the present invention may 
be a either a platinum or rhodium metal ion complex. Rhodium compounds are 
more selective for the hydrosilation reaction than are platinum compounds, 
the latter of which has been found to also catalyze undesirable side 
reactions. In the process of the present invention, the amount of catalyst 
employed is not critical, so long as proper polymerization is affected. 
However, as with any catalyst, it is preferred to use the smallest amount 
that is effective. For platinum catalysts, ordinarily 5 parts platinum 
metal per 1 million parts of siloxane will be effective to promote the 
hydrosilation reaction. Examples are those described in U.S. Pat. Nos. 
3,220,972; 3,419,593; 3,814,730; 3,775,452; and, 3,715,334. Particularly 
useful are those catalysts derived from chloroplatinic acid which has been 
treated with tetramethyldivinylsiloxane, as described in U.S. Pat. No. 
3,814,730. Rhodium catalysts ar.RTM.used at a concentration of from about 
0.1 to about 50 parts as rhodium metal per million parts of the curable 
resin. Preferably, such a catalyst is employed at from between about 1 to 
about 20 parts as rhodium metal per million parts of the curable resin. 
Most preferably, the rhodium catalyst is used at from about 2 to about 5 
parts as rhodium metal as compared to 1 million parts of the curable 
resin. The most preferred rhodium catalysts are tris(di-n-butylsulfide) 
rhodium trichloride and tris(triphenylphosphine) rhodium monochloride, the 
latter commonly known as Wilkinson's catalyst. The catalysts of the 
present invention may suitably be in the form of an ethanolic solution. 
Tertiary amines may be used to "pre-stabilize" an epoxysilicone mixture 
provided that certain rhodium catalysts are used in the reaction. Such 
tertiary amines have been found to protect against acid-catalyzed 
crosslinking of epoxy bearing compounds, including the product of the 
invention, and thereby protect against premature gelling of 
epoxy-functionalized polymers. The premature gelling may occur at any time 
epoxy-functional groups are sufficiently heated as, for example, during 
the process step of stripping light ends and solvent to prepare the 
product of the invention as described below. Tertiary amines which are 
suitable for use in practicing the present invention include 
trialkylamines, triarylamines, and mixed tertiary amines containing both 
alkyl and aryl substituents, such as diethylphenylamine, 
diphenylethylamine, etc.. A preferred tertiary amine for this use in the 
product and process of the present invention is methyldicocoamine, 
CH.sub.3 (C.sub.18 H.sub.37).sub.2 N. 
In the process of the present invention, the tertiary amine stabilizer is 
employed at a concentration effective to prevent the premature reaction of 
epoxy-functional polymers and yet still allow efficient polymerization. 
Generally, these compounds are satisfactorily used in the process of the 
invention at a concentration of between about 10 ppm and 1000 ppm, by 
weight, as compared to the weight of the curable resin. Preferably the 
tertiary amine stabilizers are employed from between about 20 ppm and 500 
ppm by weight, and most preferably from about 50 ppm to about 200 ppm by 
weight, each as compared to the weight of the curable resin. 
The onium salt photocatalyst used to affect cure in the process of the 
present invention may be any of those previously described in the 
literature. Preferred in the process of the present invention is the use 
of bisaryliodonium salt catalysts, particularly bis(dodecylphenyl) 
iodonium hexafluoroantimonate, bis(dodecylphenyl) iodonium 
hexafluoroarsenate and (4-octyloxyphenyl)(phenyl) iodinium 
hexafluoroantimonate, with the antimonate salts most preferred in 
practicing the invention. 
In the product and process of the present invention, pre-crosslinked 
epoxysilicones may be used to decrease the cure time and energy required 
by the photo-initiated cure reaction. Such epoxysilicones can be prepared 
whereby the first hydrosilation step described above is replaced by the 
hydrosilation reaction between a mixture of diallylated polyethers and 
vinyl-stopped silicones, and SiH-containing siloxanes This "pre-crosslink" 
reaction is then followed by a second hydrosilation addition of an 
epoxy-functional olefin such as described above. Pre-crosslinking of the 
silicone fluid means that there has been partial crosslinking or cure of 
the composition and offers the advantages to the present invention of 
enabling swift UV-initiated cure with little expense for energy and 
elimination of the need for solvent. In the process of the present 
invention, the ratio of vinyl-stopped and diallylated polyether to 
reactive SiH-containing silicones may be varied greatly so long as the 
total molar equivalent of reactive double bonds in the mixture is less 
that the molar equivalent of reactive SiH groups. It is preferred, 
however, that after the precrosslinking reaction there is greater than 20% 
of the reactive SiH initially present still remaining. It is most 
preferred that greater than 40% of the initial SiH groups are present 
after completion of the pre-crosslink reaction. 
The onium salt-compatible epoxysilicone-polyether linear block copolymers 
of the present invention are conveniently blended into curable 
compositions by simply mixing with the onium salt photocatalyst and other 
ingredients as the skill in the art dictates. Of the onium photocatalysts 
there is generally required from about 0.1% to about 15% by weight as 
compared to the weight of the curable composition. Of the dye sensitizers 
there may be employed any effective amount but generally from about 0.02% 
to about 5% by weight based on the weight of the total curable 
composition. The SiH-stopped siloxane is generally employed at from about 
20 to about 95 parts by weight as compared to the total weight of the 
curable resin, and the diallyl derivative of a glycol is generally 
employed at a concentration from about 5 to about 80 parts by weight as 
compared again to the total weight of the curable composition. 
The hydrosilation and reactions described above may be carried out in a 
suitable solvent in order to facilitate the rate at which the reaction 
takes place. Generally, the amount of solvent used in the process of the 
invention is kept to the minimum that will adequately disperse the 
reactants. The amount of solvent required depends upon the viscosity of 
the starting materials and can be adjusted as dictated by the art. 
Preferable solvents for the hydrosilation reaction are non-polar solvents 
particularly those which are volatile. Use of a volatile solvent is 
preferred as the solvent may then be removed from the reaction products by 
stripping the reaction under vacuum. Most preferably xylene or toluene is 
used as solvent. 
The temperature at which each step of the hydrosilation reactions is 
performed is generally that at which the reaction step is completed in a 
relatively short time interval, for example, under 2 hours per step. The 
precise temperature chosen will generally be between 25.degree. C. and 
150.degree. C., and is most preferably between 50.degree. C. and 
125.degree. C. 
After the product of the invention is formed, any solvent and low molecular 
weight products of side reactions, commonly referred to as "light ends", 
are preferably removed from the composition by heating under a vacuum. 
Such a stripping step provides a much desired solventless product. A 
rotary evaporator, used as known in the art, is conveniently employed in 
this step of the process of the invention. "Thin film" or "wiped film" 
evaporators are also conveniently employed to efficiently remove light 
ends in commercial processing. The temperature of this so-called 
"stripping" step in the process of the invention is at between about 
100.degree. C. and about 250.degree. C. Preferably this heating step is 
from between about 125.degree. C. and about 225.degree. C., and most 
preferably this step is performed at between about 150.degree. C. and 
about 200.degree. C. The pressure of the stripping step is generally below 
atmospheric, as such reduced pressure aids in the release of volatile 
molecules from the composition of the invention. Thus the lower the 
pressure that can be conveniently obtained, the better. Preferred in the 
stripping step in the process of the invention are pressures less than 
about 25 torr. Most preferred for this process step in the instant 
invention are pressures below about 10 torr. 
The UV-curable epoxysilicone-polyether linear block copolymers of the 
present invention can be applied to cellulosic and other substrates 
including paper, metal, foil, polyethylene coated Kraft paper (PEK), 
supercalendered Kraft paper (SCK), polyethylene films, polypropylene films 
and polyester films. In general, coating can be applied to these 
substrates at the desired thickness as is known in the art. For example, 
compositions of the invention are readily applicable by doctor blade. For 
applications as a release coating, the compositions are applied at a 
thickness of between about 0.1 mil and 10 mils; it is also convenient to 
refer to such coatings in terms of "coat weights", typically about 1 
g/m.sup.2. Coatings can thereafter be cured either thermally or by 
exposure to radiation, as is known in the art. 
Cure performance and adhesion of the epoxysiliconepolyether linear block 
copolymers described herein may also be enhanced by the addition of epoxy 
monomers to the compositions. For example, addition of up to 10 parts of 
an aliphatic epoxy monomer for every 10 parts epoxysiliconepolyether 
copolymer may result in compositions exhibiting superior UV cure and 
anchorage on porous cellulose paper as compared to similar compositions 
without these "reactive diluents". 
The cure characteristics of the compositions of the instant invention are 
determined by qualitatively noting the presence and extent of smear and 
migration in a siliconpolyether copolymer coating after application to a 
substrate and irradiation. Irradiation is typically performed in a 
laboratory setting by exposing the coated substrate in an RPC UV Processor 
housing two Hanovia medium pressure mercury UV lamps, each generating 200 
watts/in.sup.2. Smear is detected in an incompletely cured coating when a 
finger firmly pressed across the silicone-polyether copolymer film applied 
to a substrate leaves an obvious permanent streak. Migration is detected 
by the Scotch.RTM. cellophane tape test. The coating is considered well 
cured and migration-free if a piece of No. 610 Scotch.RTM. tape will stick 
to itself after having been first firmly pressed into the silicone 
coating, then removed and doubled back on itself. If a silicone-polyether 
copolymer coating is shown to be migration-free by means of the 
Scotch.RTM. tape test, it is considered to be a release coating because it 
adheres to the substrate with an adhesive force greater than that between 
the cured composition and the released aggressive Scotch.RTM. tape. These 
qualitative tests are universally employed to ascertain the completeness 
of cure in silicone paper release coatings. 
Due to the polyether blocks contained therein, the product of the present 
invention is much more miscible with polar molecules, particularly 
iodonium salt photo-initiators, than non-polyether-containing, 
epoxy-silicone polymers of comparable molecular weight. The product of the 
present invention, as exemplified below, is therefore much more faster 
curing despite the low concentration of epoxy function in the linear block 
copolymer than comparable epoxysilicones lacking the polyether block. In 
addition, the product of the invention also provides for coatings which 
are more flexible and elastic than those derived from UV cured, linear 
epoxy-silicones without polyether blocks of similar molecular weight. 
A general drawback to currently available, UV-curable epoxysilicones is 
that these materials are relatively brittle due to high crosslink density 
and short polysiloxane chain lengths between epoxy crosslink sites. In 
many applications, it would desirable to have more flexible and elastic 
coatings that still retain all the useful properties and ease of 
manufacture afforded by traditional silicone resins. Therefore, the 
physical characteristics of the UV-cured polysiloxane-polyether block 
copolymers were also examined. As also exemplified below, the 
incorporation of a polyether block into the siloxane backbone greatly 
increases the flexibility and elastomeric properties of the polymer as 
compared to those of similar molecular weight silicone without the 
polyether block. 
In many applications of silicone coatings, the material is applied in a 
very thin layer, for example, 0.5 mil or less. In such applications, most 
importantly with colorless coatings, it is extremely difficult to detect 
poor coating patterns. This problem is particularly troublesome when 
coating onto shiny, glossy film type liner, with conventional silicones 
that are immiscible with UV dye markers in the absence of a separate 
dispersing medium. Due to their increased miscibility with polar 
molecules, the epoxysilicone-polyether linear block copolymer of the 
present invention also provides for a silicone-based polymer that, when 
mixed with a UV-detectable dye marker, provides a coating material in 
which the coating process can be easily and accurately monitored. By 
"UV-detectable" it is meant that the presence of a dye marker is 
detectable when exposed to low wattage UV light (a so called "black 
light") but not when exposed to visible light. 
Preferably, the dye marker of the present invention is UV-detectable, so 
that clear coatings can be produced and still monitored for coating 
accuracy. However, it should be understood that many polar dyes, 
regardless of color or lack thereof, which are unsatisfactorily miscible 
with nonpolyether containing siloxanes, are suitable for use in the 
product and process of the present invention. In the preferred process and 
product of the present invention, the UV-detectable dye marker may be any 
suitable dye known, provided that the dye molecule itself is not so basic 
in nature or included in the product of the invention at such a 
concentration so as to substantially interfere with the cationic curing, 
and elastomeric properties of the epoxysilicone-polyether linear block 
copolymers of the instant invention Particularly suitable UV-detectable 
dyes include 2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole), Uvitex 
OB.RTM. (Ciba Geigy Corp., Hawthorne, N.Y.). 
As indicated in the examples below, when the product of the invention 
incorporates a UV-detectable marker dye, the sufficiency of even very thin 
silicone coatings is easily monitored by use of a low intensity "black 
light". Application of the resin to a substrate can thus be either 
monitored visually, or through mechanical means which detect the absence 
of the appropriate UV light emanating from the applied resin. The 
incorporation of a dye marker in the product of the invention thus allows 
an economical yet highly efficient means for determining the adequacy of 
coating. 
EXPERIMENTAL 
Unless otherwise indicated, all resins and catalysts are available from 
General Electric Silicones, Waterford, N.Y. In the shorthand notation of 
polymer structure below, the following apply: 
______________________________________ 
M represents 
(CH.sub.3).sub.3 SiO.sub.0.5 ; 
M.sup..epsilon. represents 
##STR4## 
M.sup.H represents 
(CH.sub.3).sub.2 (H)SiO.sub.0.5 ; 
M.sup.Vi represents 
(CH.sub.2 CH)(CH.sub.3).sub.2 SiO.sub.0.5 ; 
D represents 
(CH.sub.3).sub.2 SiO; 
D' represents 
SiO(CH.sub.3).sub.2 CH.sub.2 CH.sub.2 
D.sup..epsilon. represents 
##STR5## 
D.sup.H represents 
(CH.sub.3)(H)SiO; and, 
______________________________________ 
subscripts represent the number of such units. 
EXAMPLE 1 
Epoxysilicone-polyether linear block copolymer 
Fifty three grams of an SiH-stopped linear polydimethylsiloxane, of 
approximate formula M.sup.H D.sub.34 M.sup.H, 750 ppm H, for a total of 
0.04 moles reactive SiH, were weighed into a 500 cc flask with 2.74 grams 
TEGDAE (0.01 mole, corresponding to 0.02 mole allyl) plus 50 grams 
toluene. The mixture was thoroughly stirred, after which the baseline SiH 
content was determined by Fourier Transform Infrared Spectroscopy (FTIR) 
(The strong SiH absorbance at 2200 cm.sup.-1 being monitored). A first 
hydrosilation reaction was then initiated by the addition of 0.02 grams of 
SPBD platinum hydrosilation catalyst as defined in U.S. Pat. No. 
3,775,452, after which the total reaction mixture was brought to 
75.degree. C. The reaction was maintained at this temperature for 1 hour, 
after which the SiH content was again determined. At this point the peak 
height, corresponding to the amount of unreacted SiH, was 52% that of the 
starting peak height (theoretical value is 50% starting peak height). 
Three grams of 4-vinylcyclohexeneoxide (VCHO; 0.024 moles) were next added 
to the reaction mixture and the temperature maintained for an additional 
hour at 75.degree. C. After the second hydrosilation reaction, no SiH was 
detected by FTIR. 0.005 grams of methyldicocoamine stabilizer was added to 
the reaction solution to prevent premature gelling, after which the 
solution was stripped of solvent and remaining VCHO by heating at 
160.degree. C. for one hour, in vacuo (less than 25 torr). The process 
resulted in 56 grams of a 116 cstk fluid product as measured on a 
Brookfield LVF #4 viscometer at 60 rpm, with a refractive index 
n.sub.D.sup.25 =1.4139. Based upon the progressive loss of SiH during the 
reaction, the fluid has a average structure of 
EQU M.epsilon.D.sub.34 D'O[(CH.sub.2).sub.2 O].sub.4 (CH.sub.2).sub.2 
D'D.sub.34 M.epsilon. 
and possesses an Epoxy Equivalent Weight of 2911. 
EXAMPLE 2 
Non-ether containing comparative example 
One hundred grams of an SiH-stopped polydimethylsiloxane of approximate 
formula M.sup.H D.sub.75 M.sup.H, 350 ppm reactive H or 0.035 moles total 
reactive H, were reacted with 6 grams VCHO (0.048 moles) for one hour at 
70.degree. C., in the presence of 0.02 grams platinum hydrosilation 
catalyst as defined in U.S. Pat. No. 3,775,452. After completion of the 
incubation, the reaction was stripped of solvent and excess VCHO as in 
Example 1. The resulting isolate was 103 grams of a 146 ctsk viscosity 
fluid product, n.sub.D.sup.25 =1.4083, with the approximate average 
formula M.epsilon.D.sub.75 M.epsilon.. 
EXAMPLE 3 
UV Cure Analysis of the products of Examples 1 and 2 
100 parts of test silicone resin as produced in Examples 1 and 2, were 
individually blended with 2 parts of a 50% bis(dodecylphenyl)iodonium 
hexafluoroantimonate sensitized photocatalyst solution (described in U.S. 
Patent application filed June 14th, 1991, attorney docket 60SI-1444). The 
resulting mixture was then manually coated as a 2 mil thick coating on 
polyethylene kraft substrate, or as thinner coatings (approximately 1.5 
g/cm.sup.2 ct.wt.) on supercalendered Kraft paper. Coated specimens were 
cured by exposure to UV light as previously described in U.S. Pat. No. 
4,990,546, and the minimum UV light flux required for cure to smear- and 
migration-free surfaces determined with an International Light, Model 700A 
Research Photometer equipped with a Model A309 Lightbug accessory. The 
results of these tests for a series of epoxysilicone-polyether copolymers 
and epoxy-stopped linear silicone control polymers are given in Table 1. 
TABLE 1 
______________________________________ 
2 MIL THIN 
UV FILM 
EXAM- FLUX FLUX 
PLE STRUCTURE (mJ/cm.sup.2) 
(mJ/cm.sup.2) 
______________________________________ 
1 M.sup..epsilon. D.sub.36 D'O[(CH.sub.2).sub.2 O].sub.4 D'D.sub.36 
M.sup..epsilon. 27 nt 
2 M.sup..epsilon. D.sub.75 M.sup..epsilon. 
250 nt 
3 M.sup..epsilon. D.sub.22 D'O[(CH.sub.2).sub.2 O].sub.4 D'D.sub.22 
M.sup..epsilon. 33 30 
4 M.sup..epsilon. D.sub.40 M.sup..epsilon. 
50 80 
5 M.sup..epsilon. D.sub.34 D'O[(CH.sub.2).sub.2 O].sub.4 D'D.sub.34 
M.sup..epsilon. 42 86 
6 M.sup..epsilon. D.sub.40 D'O[(CH.sub.2).sub.2 O].sub.4 D'D.sub.40 
M.sup..epsilon. 42 86 
7 M.sup..epsilon. D.sub.11 D'O[(CH.sub.2).sub.2 O].sub.4 D'D.sub.11 
M.sup..epsilon. 63 nt 
8 M.sup..epsilon. D.sub.54 D'O[(CH.sub.2).sub.2 O].sub.9 D'D.sub.54 
M.sup..epsilon. 177 nt 
______________________________________ 
nt = not tested 
Physical Characteristics of UV-Cured Films in Example 3. 
Thick sheets of the blends given in Example 3 (approximately 6 mils) were 
manually cast and thereafter exposed to sufficiently high UV flux to 
thoroughly cure the films. Standard ASTM tensile bars were cut from the 
slabs, and peak tensile and elongation at break were measured on an 
Instron testing device. The results of these tests are tabulated in Table 
2. 
TABLE 2 
______________________________________ 
% TEN- 
EXAM- ELONGA- SILE 
PLE STRUCTURE TION (PSI) 
______________________________________ 
1 MD.sup..epsilon..sub.3 D.sub.20 M 
nd nd 
2 M.sup..epsilon. D.sub.22 D'O[(CH.sub.2).sub.2 O].sub.4 D'D.sub.22 
M.sup..epsilon. 3-4 16-18 
3 M.sup..epsilon. D.sub.40 M.sup..epsilon. 
1-4 14-19 
4 M.sup..epsilon. D.sub.34 D'O[(CH.sub.2).sub.2 O].sub.4 D'D.sub.34 
M.sup..epsilon. 23-31 27-36 
5 M.sup..epsilon. D.sub.36 D'O[(CH.sub.2).sub.2 O].sub.4 D'D.sub.36 
M.sup..epsilon. 33-40 27-36 
6 M.sup..epsilon. D.sub.75 M.sup..epsilon. 
16-22 30-36 
7 M.sup..epsilon. D.sub.40 D'O[(CH.sub.2).sub.2 O].sub.4 D'D.sub.40 
M.sup..epsilon. 57-67 38-58 
8 M.sup..epsilon. D.sub.54 D'O[(CH.sub.2).sub.2 O].sub.9 D'D.sub.54 
M.sup..epsilon. 60-80 21-32 
______________________________________ 
nd = too brittle to measure 
EXAMPLE 9 
Pre-crosslinked epoxysilicone-polyether linear block copolymer containing a 
UV-detectable dye marker 
Fifty grams of SPBD silicone resin grade 88405, approximate structure 
MD.sub.15 D.sup.H.sub.4 M, corresponding to 0.19% H, and 20 grams of SPBD 
silicone grade 88934, a 900 cstk vinyl-stopped dimethylsilicone fluid, 
approximate structure M.sup.Vi D.sub.150 M.sup.Vi, and 10 grams of an 
allyl-stopped polyether of approximate structure CH.sub.2 .dbd.CHCH.sub.2 
O(CH.sub.2 CH.sub.2 O).sub.11 CH.sub.2 CH.dbd.CH.sub.2, were dispersed in 
100 grams toluene, thoroughly mixed, and a reference FTIR of the solution 
obtained 0.07 grams of a solution of RhCl.sub.3 
[[(CH.sub.3)(CH.sub.2).sub.3 ].sub.2 S].sub.3 in ethanol, 1.36% rhodium by 
weight, were then added and the reaction mix brought to 110.degree. C. and 
held at this temperature for about 1.5 hours. Infrared analysis showed 
that 65% of the starting SiH remained unreacted at this point. 0.008 grams 
CH.sub.3 (C.sub.18 H.sub.37).sub.2 N stabilizer were then added along with 
7.5 grams VCHO. The reaction was held at 110.degree. C. for an additional 
2 hours, at which point the batch was determined to be free of unreacted 
SiH. Sufficient Uvitex OB fluorescent dye was introduced into the reaction 
mixture as a 2% solution in methylene chloride, to furnish 100 ppm dye, by 
weight, in the final product after stripping off the solvent and various 
siloxane "light ends" (low boiling point side reaction products) in vacuo. 
Eighty grams of product was obtained as a 36,000 cps viscosity fluid, 
having a refractive index n.sub.D.sup.25 =1.4191. The dye marker proved to 
be soluble in the product at the 100 ppm concentration. 
EXAMPLE 10 
An epoxy-stopped polydimethylsilicone/polyether block copolymer was 
prepared as in Example 5, with the exception that 10 grams of 
vinyl-stopped silicone fluid (grade 88934) and 10 grams of the same 
diallylpolyether cited in Example 5 were used as the "pre-crosslinkers" 
reacting with the grade 88405 SiH fluid prior to the addition of VCHO. The 
product yield was 66 grams of a 3844 cstk fluid, with a refractive index 
of n.sub.D.sup.25 =1.4212. As with the product in Example 5, Uvitex OB 
fluorescent dye, at 100 ppm, was completely miscible with this product. 
EXAMPLE 11 
An epoxy-stopped polydimethylsilicone-polyether block copolymer was 
prepared as in Example 5, with the exception that 5 grams of 88934 
vinyl-stopped silicone fluid and 10 grams of diallylpolyether was used as 
the "pre-crosslinkers" reacting with the 88405 SiH silicone fluid prior to 
the addition of VCHO. The product yield was 66 grams of a 1982 cstk 
viscosity fluid, with a refractive index n.sub.D.sup.25 =1.4214. Uvitex 
OB.sup.R fluorescent dye, at a concentration of 100 ppm, by weight, was 
also completely miscible with this product. 
EXAMPLE 12 
UV Cure of the Products of Examples 5, 6 and 7 
The UV cure characteristics of the products obtained in Examples 5, 6 and 7 
was assessed by blending 100 parts of the respective polymers with 2 parts 
of the sensitized iodonium photocatalyst solution used in the previous UV 
cure Example described, followed by manually applying a 0.5 mil coating of 
these compositions to polyethylene-coated Kraft paper. The minimum UV flux 
needed to render the coating smear- and migration-free was then 
determined. The product of Example 6, without the dye marker present, 
required a UV flux of about 35 mJ/cm2 for cure, whereas with the dye 
marker at 100 ppm, this material required about 80 mJ/cm2 UV flux. 
Coatings with the dye marker proved to be easily detectable under a low 
power "black light" source. It should be noted that, although the dye 
marker present at 100 ppm does slow the UV cure response by competing with 
iodonium photocatalysts for available deep UV radiation, acceptably prompt 
UV cure is still obtained. 
EXAMPLE 13 
95 grams of SiH-containing polymer 88405 (described above) were dispersed 
in a 500 cc flask with 100 grams toluene plus 10 grams of a diallylated 
polyethyleneoxide, approximate structure CH.sub.2 .dbd.CHCH.sub.2 
O(CH.sub.2 CH.sub.2 O).sub.10 CH.sub.2 CH.dbd.CH.sub.2, and 0.04 grams of 
the sensitized iodonium photocatalyst solution described in Example 3. The 
polar polyether was not completely miscible in this reaction mixture, even 
at 100.degree. C. Nonetheless, the agitating catalyzed blend was brought 
to 100.degree. C. for 2 hours, then cooled, at which time it was observed 
that discrete undispersed polyether was no longer visible in the reaction 
medium, a strong indication that the polyether had reacted with a portion 
of SiH present on the 88405 fluid. Ten grams of vinyl-stopped silicone 
fluid (GES 88568 grade), approximate formula M.sup.Vi D.sub.100 M.sup.Vi, 
were then added to the reaction mixture, and the batch returned to 
100.degree. C. for 2 hours to effect the reaction of the vinyl-stopped 
silicone with some of the SiH as yet unreacted. Finally, 18 grams of VCHO 
was slowly added by dropping it into the reaction mixture at 80.degree. C. 
Examination of this reaction mixture subsequent to VCHO addition and 2 
hour hold revealed that no unreacted SiH was detectable. Removal of 
solvent and other low boilers in vacuo afforded 126 gram yield of a 739 
cstk viscosity, clear fluid product. 
COMATIVE EXAMPLE 13A 
95 grams of the SiH-containing polymer 88405 (described above) plus 20 
grams of the vinyl-stopped polymer 88568 were dispersed in 100 grams 
toluene with 0.04 grams of the catalyst solution described in Example 3. 
This blend was maintained at 80.degree. C. to react the vinyl-stopped 
silicone with a portion of the SiH present in the reaction mixture After 
two hours, 23 grams of VCHO were reacted with the remainder of SiH as in 
Example 13. Removal of the solvent and low boilers yielded 130 grams of a 
212 cstk viscosity, clear fluid product. 
100 parts of the product of Example 13 proved miscible with 1 part of 
(4-octyloxyphenyl)(phenyl)iodonium hexafluoroantimonate (described in U.S. 
Pat. No. 4,882,201). 0.5 mil coatings of this photo-curable mixture were 
applied to PEK substrate, and found to crosslink to tack-free, 
migration-free adhesive coatings when exposed to 70 mJ/cm.sup.2 focused 
ultraviolet light. The product of Example 13 was similarly miscible with 
the bis(dodecylphenyl)iodonium hexafluoroantimonate catalyst used in the 
previous Examples; catalyzed mixtures of 1 part of the latter catalyst 
plus 100 parts of the product of Example 13 cured to similar 0.5 mil 
abhesive coatings on PEK on exposure to 85 mJ/cm.sup.2 ultraviolet light. 
By contrast the polymer product of Comparative Example 13A was immiscible 
with the (4-octyloxyphenyl)(phenyl)iodonium hexafluoroantimonate catalyst, 
and could only be cured in the presence of the bis(dodecylphenyl)iodonium 
hexafluoroantimonate catalyst. 
In addition to the above, the polymer product of Example 13 was quite 
miscible with 100 ppm of the Uvitex OB.sup.R fluorescent dye marker, 
whereas the product of Comparative Example 13A would not accommodate this 
additive in any useful concentration. Accordingly, 20% solutions of 
photo-catalyzed polymers from Example 13 and Comparative Example 13A were 
prepared in hexane/acetone. Each solution included 1 part 
bis(dodecylphenyl)iodonium hexafluoroantimonate catalyst per 100 parts 
polymer. The solution containing polymer from Example 13 also included 100 
ppm Uvitex OB.sup.R dye marker (per part of polymer). These solutions were 
coated onto glossy white polyethylene coated Kraft stock using a #2 
wire-rounded rod mounted in a mechanical lab coater. Solvent was flashed 
off during brief exposure to two 300 watt ultraviolet lamps in the 
above-described RPC Lab Processor, which cured each coating to smear- and 
migration-free adhesive surfaces. The coat weight in each case was 
determined to be 1.1 g/m.sup.2, typical of silicone release coatings. 3 
mil (dry) of solvent-borne aggressive acrylic PSA, Ashland 1085, were 
applied atop the cured silicone, then cured thermally before a face sheet 
of supercalendered Kraft (SCK) was firmly affixed to the adhesive layer. 
The resulting construction was cut into 2 inch wide tapes, and the force 
required to remove the silicone/PEK lamina from the adhesive/SCK lamina 
measured at 400 in/min. pull speed, 180.degree. pull angle. The 
non-polyether containing coating derived from Comparative Example 13A 
epoxysilicone released the PSA when 42 g/2 inch force was exerted; the 
polyether block copolymer-containing epoxysilicone from Example 13 
released the same PSA lamina with 90 g/2 inch force. While the presence of 
about 8% by weight polyether appeared to double the release compared to 
the non-polyether silicone, 90 g/2 inch release versus the aggressive 
Ashland 1085 acrylic PSA is acceptable for most release liner 
applications. Also, the cured film of Example 13 on the glossy PEK sheet 
was clearly outlined under "black light" due to the 100 ppm fluorescent 
dye marker, while the extent and quality of the coating from Comparative 
Example 13A was impossible to ascertain visually. It must be pointed out 
that this coating experiment was conducted using a solvent vehicle solely 
because there was no other means readily available for obtaining an even 1 
g/m.sup.2 silicone deposition without solvent-assisted coating. 
It is understood that various other modifications will be apparent to and 
can be readily made by those skilled in the art without departing from the 
scope and spirit of this invention. Accordingly, it is not intended that 
the scope of the claims appended hereto be limited to the description set 
forth above but rather that the claims be construed as encompassing all of 
the features of patentable novelty which reside in the present invention, 
including all features which would be treated as equivalents thereof by 
those skilled in the art to which the invention pertains.