Catalyst system, process, and silicone compositions

The invention relates to a catalyst system for reacting a silanol group with an alkoxysilane containing a polymerizable ethylenically unsaturated group. The catalyst system includes an organo-lithium reagent and a hydroxylamine. The catalyst system, permits reaction of the silanol group with alkoxysilanes containing rapidly polymerizable ethylenically unsaturated groups, such as an acryloxyalkyl group, for instance an acryloxypropyl group.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention is directed to a catalyst system, a process and 
silicone compositions. 
2. Brief Description of Related Technology 
Organosiloxane fluids having alkoxy groups which polymerize by reaction 
with moisture and groups which polymerize by free-radical processes are 
known [see U.S. Pat. No. 5,300,608 (Chu) and U.S. Pat. No. 5,663,269 
(Chu), the disclosures of each of which are hereby expressly incorporated 
herein by reference]. As demands for ever-faster polymerizing materials 
have arisen, more reactive free radical polymerizing groups have been 
incorporated into the alkoxy group containing organosiloxanes. However, it 
has been found difficult to prepare organosiloxane compositions which 
contain reactive free-radical polymerizing groups, such as acryloxyalkyl 
groups, by reaction of a silanol with a dialkoxy or trialkoxy silane 
containing a reactive acryloxyalkyl group. 
U.S. Pat. No. 5,300,608 (Chu) and U.S. Pat. No. 5,663,269 (Chu) disclose 
processes for capping silanol groups with alkoxy silanes containing groups 
with polymerizable double bonds by reaction of the silanol with an 
alkoxysilane in the presence of organo-lithium reagents. These processes 
provide capping of a major proportion of the silanol groups. However, 
oftentimes the organo-lithium reagents do not produce suitable capping 
when the alkoxy silane contains a reactive group, such as an acryloxyalkyl 
or allyl group. 
U.S. Pat. No. 4,798,889 (Pleuddemann) refers to a method of stabilizing 
unsaturated organosilicones using hydroxylamines, and U.S. Pat. No. 
4,912,239 (Bank) refers to an improvement in the method of preparing an 
alkoxysilane in the presence of hydroxylamine as a polymerization 
stabilizer. However, these methods refer to stabilizing organosilicones 
and alkoxysilicones once formed; they do not refer to catalyzing the 
process of capping silanol groups with alkoxysilanes containing groups 
with polymerizable double bonds. 
Accordingly, it would be desirable to provide a catalyst system which is 
capable of end capping a major portion of the silanol groups by reaction 
with alkoxysilanes containing a highly reactive acryloxy group or allyl 
group. 
SUMMARY OF THE INVENTION 
The present invention is directed to a catalyst system and process for 
capping silanol groups with alkoxysilanes containing groups with 
polymerizable double bonds. Particularly, the invention relates to a 
catalyst system and process for capping silanol groups with alkoxysilanes 
containing groups with highly reactive double bonds, such as acryloxyalkyl 
groups, allyl and vinyl groups. 
According to the present invention, a catalyst system including an 
organo-lithium reagent and hydroxylamine is provided to react a polyalkoxy 
silane, such as a dialkoxy or trialkoxy silane, containing a free 
radically polymerizable group thereby capping the silanol group, with the 
alkoxy silane having at least one ethylenically unsaturated polymerizable 
group. 
The process is ordinarily conducted by reacting a mixture of the silanol 
reactant with at least one polyalkoxy silane, such as a dialkoxy or 
trialkoxy silane containing at least one polymerizable ethylenically 
unsaturated group in the presence of the catalyst system at a temperature 
in the range of about room temperature to about 150.degree. C., such as 
from about 50.degree. C. to about 120.degree. C., particularly from about 
60.degree. C. to about 100.degree. C. The reaction is ordinarily conducted 
for a period of time of from about one hour to about ten hours, depending 
upon the concentration of catalyst and the reactivity of the silanol and 
the alkoxysilane reactants. 
The catalyst system and the process are useful for end-capping 
silanol-terminated polysiloxanes, particularly polysiloxanes which are 
terminated with silanol groups at two ends. Compositions including the 
silanol end-capped polysilicones cure by reaction with moisture and by 
free radical mechanisms, such as ultraviolet light or free radical 
catalysis. 
The invention will be further understood upon a reading of the section 
entitled "Detailed Description of the Invention", which follows. 
DETAILED DESCRIPTION OF THE INVENTION 
The silanol-terminated reactant can be virtually any useful 
silanol-terminated material within the general formula I as shown below: 
##STR1## 
where A represents a polymer or copolymer backbone, which can be any 
number of combinations of polyurethane, silicone, polyamide, polyether, 
polyester and the like; and R.sup.1 and R.sup.2 may be the same or 
different and are monovalent hydrocarbyl groups having up to 10 carbon 
atoms (C.sub.1-10), or halo- or cyano-substituted hydrocarbyl groups; and 
R.sup.3 is a monovalent C.sub.1-10 hydrocarbyl group or OH. 
Desirable reactants within formula I include silanol-terminated 
organopolysiloxanes within the formula II as shown below: 
##STR2## 
where R.sup.1, R.sup.2 and R.sup.3 are as defined above. Within structure 
II, desirable groups for R.sup.1 and R.sub.2 include C.sub.1-10 alkyl, 
such as methyl, ethyl and isopropyl, although aryl groups, such as phenyl, 
vinyl groups may also be used. Desirable groups for R.sup.3 include OH. 
The number of repeating units determines the molecular weight and hence the 
viscosity of the starting material. Thus, n is an integer, for example, 
from about 1 to about 1,200, such as about 10 to about 1,000. The 
viscosity may be readily chosen for a particular product application, 
particularly because the alkoxy terminated end product of the reaction 
oftentimes has substantially the same viscosity as the silanol-terminated 
reactant. Viscosities of these silanol-terminated organopolysiloxanes are 
often within the range of from about 1 cps to about 150,000 cps (measured 
using a Brookfield viscometer, at a temperature of about 25.degree. C.). 
The viscosity range for those used in the present invention is desirably 
from about 100 cps to about 60,000 cps. 
An example of one such silanol-terminated organo-polysiloxane is a 
polydimethylsiloxane within the formula III as shown below: 
##STR3## 
where n is from about 50 to about 160, such as from about 50 to about 70. 
The alkoxysilane reactant includes a silane containing at least two alkoxy 
groups and at least one group containing an ethylenically unsaturated 
polymerizable double bond. More specifically, the alkoxysilane reactant 
includes at least one compound of the formula (R.sup.4 ).sub.a 
(R.sup.5).sub.b Si (OR.sup.6).sub.4-(a+b) (IV), where R.sup.4 and R.sup.5 
may be the same or different monovalent groups and may contain an 
ethylenically unsaturated polymerizable double bond. Desirably, R.sup.4, 
R.sup.5 and R.sup.6 each contain from 1-10 carbon atoms and may contain 
heteroatoms, such as O, N, or S, and may be substituted with halo atoms, 
such as fluorine or chlorine. Desirably, at least one of R.sup.4 and 
R.sup.5 is chosen from methyl, ethyl, isopropyl and phenyl, R.sup.6 is 
chosen from methyl, ethyl, isopropyl and --CH.sub.2 CH.sub.2 OCH.sub.3, 
and a is 0, 1 or 2; b is 0, 1 or 2; and a+b is 1 or 2. 
It is particularly desirable for at least one of R.sup.4 and R.sup.5 to be 
acryloxy propyl or allyl. 
Representative polyalkoxysilanes useful in the present invention include: 
(CH.sub.3 O).sub.3 SiCH.dbd.CH.sub.2, (C.sub.2 H.sub.5 O).sub.3 
SiCH.dbd.CH.sub.2, (CH.sub.3 O).sub.3 SiCH.sub.2 CH.dbd.CH.sub.2, 
(CH.sub.3 O).sub.3 SiCH.sub.2 (CH.sub.3)C=CH.sub.2, CH.sub.2 
.dbd.CHSi(OCH.sub.2 CH.sub.2 OCH.sub.3).sub. 3, (CH.sub.3 O).sub.3 Si 
(CH.sub.2).sub.3 OOC(CH.sub.3)C.dbd.CH.sub.2, (CH.sub.3 O).sub.2 Si 
((CH.sub.2).sub.3 OOC--(CH.sub.3)C.dbd.CH.sub.2).sub.2, (CH.sub.3 O).sub.3 
Si(C.sub.6 H.sub.4)--CH.dbd.CH.sub.2, (CH.sub.2 H.sub.5 O).sub.3 
SiCH.sub.2 --(C.sub.6 H.sub.4)--CH.dbd.CH.sub.2, (C.sub.2 H.sub.5 O).sub.3 
SiCH.sub.2 CH.dbd.CH.sub.2, (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.2 
--(C.sub.6 H.sub.4)--CH.sub.2 OC(O)C(CH.sub.3).dbd.CH.sub.2, (C.sub.2 
H.sub.5 O).sub.3 Si(CH.sub.2).sub.3 OOC(CH.sub.3)C.dbd.CH.sub.2, (CH.sub.3 
O).sub.2 Si(CH.dbd.CH.sub.2).sub.2, (CH.sub.3)(CH.sub.2 
.dbd.CH)Si(OCH.sub.3).sub.2, and (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.3 
OOCCH.dbd.CH.sub.2. 
The catalyst system and process of the present invention are particularly 
effective in reacting silanols with alkoxysilanes having polymerizable 
ethylenic bonds which are sufficiently rapid reacting that the capped 
composition is not formed in a commercially efficient manner by use of 
organo-lithium reagent catalysts alone. The catalyst system and process of 
the invention are particularly useful in reacting silanol terminated 
(co)polymers with compounds such as trimethoxyacryloxypropylsilane, 
triethoxyacryloxypropylsilane, triemethoxyacryloxyethylsilane, 
dimethoxydimethacryloxypropylsilane, triethoxyallylsilane and the like. 
The catalyst system includes at least one organo-lithium reagent of the 
formula LiR.sup.7 (V) where the organo group R.sup.7 is chosen from 
C.sub.1-18 alkyl, C.sub.1-18 aryl, C.sub.1-18 alkylaryl, C.sub.1-18 
arylalkyl, C.sub.2-18 alkenyl, and C.sub.2-18 alkynyl groups; 
amine-containing groups; and organosilicone-containing groups. Desirably, 
R.sup.7 is C.sub.1-18 alkyl, such as n-butyl. 
The catalyst system is present in catalytically effective amounts and 
enhances the process and the quality of the product made therefrom. 
The organo-lithium reagent is desirably an alkyl lithium, such as methyl, 
n-butyl, sec-butyl, t-butyl, n-hexyl, 2-ethylhexyl and n-octyl lithium. 
Other useful catalysts include phenyl lithium, vinyl lithium, lithium 
phenylacetylide, lithium (trimethylsilyl) acetylide, lithium silanolates 
and lithium siloxanolates. The organo group can also be an 
amine-containing group, such as dimethylamine, diethylamine, 
diisopropylamine or dicyclohexylamine, or a silicone-containing group. 
Useful lithium silanolates may be within the formula LiOSiR.sup.8 R.sup.9 
R.sup.10 (VI), where R.sup.8 and R.sup.9 are monovalent hydrocarbon 
groups, such as C.sub.1-10 alkyl, for instance methyl, ethyl and butyl, as 
well as aryl, for instance phenyl, and R.sup.10 is C.sub.1-18 alkyl or 
C.sub.1-18 aryl. 
Useful lithium siloxanolates may be within the formula LiO(SiR.sup.8 
R.sup.9 O).sub.t SiR.sup.8 R.sup.9 R.sup.10 (VII), where R.sup.8 and 
R.sup.9 are as described above, R.sup.10 is as described above and t is an 
integer, such as from 1 to 10. 
The organo-lithium reagents are used in catalytically effective amounts. 
Generally, the amount varies with the chosen catalyst and reactant 
materials, but about 1 to about 1000 ppm of lithium (calculated as lithium 
metal based on the weigh of the reactants) is ordinarily within the useful 
range. A particularly range is from about 5 to about 500 ppm, such as from 
about 8 ppm to about 200 ppm of lithium based on the weight of the 
reactants. 
The hydroxylamine compounds useful in the catalyst system of the invention 
are compounds within the formula Q.sub.2 NOH (VIII), in which Q 
independently is an alkyl group having C.sub.1-12, a cycloalkyl group 
having C.sub.5-12 or an aryl group having C.sub.6-9. Examples of specific 
alkyl groups which are suitable include methyl, ethyl, propyl, isopropyl, 
butyl, ethylhexyl, nonyl, decyl and dodecyl groups. Specific cycloalkyl 
groups include cyclopentyl, cyclohexyl and cyclooctyl groups. Illustrative 
of the aryl groups are phenyl, benzyl, styryl, tolyl and xenyl groups. The 
Q groups may be mixed so that hydroxylamine compounds, such as 
ethylbenzylhydroxylamine, ethylcyclopentylhydroxylamine, 
ethylmethylhydroxylamine, and the like, are contemplated herein. 
The hydroxylamine compound may also be selected from compounds within the 
formula IX 
##STR4## 
where G is an alkyl or alkenyl group of C.sub.5-11 --(CH.sub.2).sub.j --, 
where j is 5 to 8, particularly 5. 
Certain of the hydroxylamine compounds useful in the present invention are 
well known in the art [see e.g., U.S. Pat. No. 4,912,239 (Bank), the 
disclosure of which is hereby expressly incorporated herein by reference] 
and may generally be prepared by reacting hydroxylamine or a substituted 
hydroxylamine with an activated halogen compound in the presence of an 
acid acceptor or by oxidizing an amine with a peroxy compound such as 
hydrogen peroxide followed by reduction of the intermediate formed. 
Alternatively, the oxime of a cyclic ketone may be reduced to the 
corresponding hydroxylamine. 
It is desirable that the hydroxylamine compound be selected from 
diethylhydroxylamine or dibenzylhydroxylamine, with diethylhydroxylamine 
being more desirable. 
The process of the invention provides a process of capping silanol groups 
with alkoxysilanes which is not believed possible using organo-lithium or 
hydroxylamine catalysts alone under reasonable conditions. The process is 
useful particularly with alkoxysilane containing acryloxyalkyl group and 
particularly acryloxypropyl groups. 
More specifically, the process of the invention includes the steps of 
forming a mixture of the silanol-terminated reactant, alkoxysilane, and 
catalyst system of organolithium reagent and hydroxylamine, and reacting 
the mixture with agitation in the absence of moisture until the desired 
amount of silanol capping has occurred. Where substantially complete 
capping is desired, the equivalent ratio of silanol groups to alkoxysilane 
is desirably from about 1:.95 to about 1:1.5, and more desirably from 
about 1:1 to about 1:1.2. Any volatile materials remaining in the reaction 
mixture after the capping has reached the required level can be removed by 
a mild heating under reduced pressure. An inert gas can be passed through 
the reaction mixture during the removal of the volatile materials. 
The process can be carried out at temperatures of from about room 
temperature to about 150.degree. C. The temperature at which the process 
is conducted depends on the particular reactants chosen, the identity and 
amount of the constituents of the catalyst system and the length of time 
the reaction can proceed. 
The catalyst system comprises a ratio by weight of lithium (based on the 
weight of lithium metal in the organo-lithium reagent) to hydroxylamine of 
from about 1:1000 to about 1:1, desirably from about 1:2 to about 1:200, 
such as from about 1:3 to about 1:50. The ratio of lithium to 
hydroxylamine depends on the composition of the hydroxylamine; higher 
molecular weight hydroxylamines use a higher ratio of hydroxylamine to 
lithium in the catalyst system. 
The organo-lithium reagent and the hydroxylamine are nonetheless present in 
catalytic amounts. 
Generally, the amount of lithium in the reaction mixture is from 1 ppm to 
about 1000 ppm, desirably from about 5 ppm to about 500 ppm, such as from 
about 8 ppm to about 200 ppm, based on the weight of the reactants. 
The amount of hydroxylamine in the reaction mixture ranges from about 10 
ppm to about 1000 ppm, desirable from about 30 to about 350 ppm, such as 
from about 50 ppm to 250 ppm, based on the weight of the reactants. 
The amount of the organo-lithium reagent and the hydroxylamine used in the 
catalyst system depends on the reactivity of the silanol group-containing 
reactant and the reactivity of the alkoxysilane containing the 
polymerizable ethylenically unsaturated group. The amount chosen may be 
readily determined by those persons skilled in the art. 
After the reaction, the lithium catalyst can be reacted with carbon 
dioxide, precipitated as lithium carbonate and removed from the reaction 
mixture by liquid-solid separation means such as centrifuging, filtration 
and the like. Low molecular weight hydroxylamine and other low boiling 
point materials can be separated by heating the reaction mixture under 
reduced pressure. 
The reaction product comprises a capped silanol within the formula X as 
shown below: 
##STR5## 
where R.sup.1, R.sup.2, R.sup.4, R.sup.5, R.sup.6, A, a and b are as 
defined above, and R.sup.12 is a monovalent hydrocarbyl group or 
##STR6## 
Due to the presence of at least one O--R.sup.6 group and at least one 
polymerizable ethylenically unsaturated group, the "capped silanol" can 
react with moisture and react by a free radical mechanism. The free 
radicals can be generated by exposure to UV light in the presence of a 
free radical initiator. 
The present invention further relates to compositions capable of curing by 
both photo- and moisture-curing mechanisms and having a substantially 
shelf stable viscosity. These compositions include: 
(a) a reactive organopolysiloxane prepared using the catalyst system as 
described herein, which reactive organopolysiloxane has at least two 
alkoxy groups on both terminal ends and at least one photocurable group on 
at least one terminal end; 
(b) an effective amount of a photoinitiator; and 
(c) an effective amount of a moisture curing catalyst. 
The reactive organopolysiloxane of (a) is the reaction product of an 
organopolysiloxane having at least both ends terminating with a silanol 
group with a silane containing at least three alkoxy groups and at least 
one photo-curable group. 
A particularly desirable organopolysiloxane prepared by the reaction 
described above is within the formula XI where R.sup.3 is an acryloxy 
propyl group, CH.sub.2 CH--COOC.sub.3 H.sub.6, R.sup.4 is methyl or ethyl, 
and R.sup.1 and R.sup.2 are as described above, such as methyl. 
Accordingly, such particularly desirable organopolysiloxanes within 
formula: 
##STR7## 
are where A is the acryloxypropyl group, and n is from 1 to 1,200. 
Due to the presence of both alkoxy and acrylate groups, this 
organopolysiloxane is capable of curing by both moisture and photo curing 
mechanisms. Thus, for example, this polymer fluid material or a 
composition comprising the material can be subjected to UV light in the 
presence of a photoinitiator to partially cure or gel the material, which 
can then be allowed to cure further by moisture under ambient conditions. 
The resultant alkoxy end-capped organosiloxane fluids can then be mixed 
with other conventional additives such as curing agents, inorganic 
fillers, adhesion promoters, pigments, moisture scavengers and the like to 
form a one-part curable composition. Inorganic fillers, such as 
hydrophobic fumed silica or quartz, serve to impart desirable physical 
properties to the cured material. Moisture scavengers, such as 
methyltrimethoxysilane and vinyltrimethyloxysilane, are useful as well. 
These curable compositions are obtained by adding to 100 parts (by weight) 
of the functionalized polymer prepared according to the process of the 
present invention: 
(a) 0 to 250 parts of inorganic fillers; 
(b) 0 to 20 parts, such as 0 to 10 parts, of adhesion promoters, for 
instance silanes or polysiloxanes, such as 
glycidoxypropyltrimethoxysilane, aminopropyltrimethoxysilane, 
methacryloxypropyltrimethoxysilane, and 
aminoethylaminopropyltrimethoxysilane simultaneously bearing per molecule: 
(i) at least one C.sub.3 -C.sub.15 organic group bonded by a SiC bond to 
the silicon atom and substituted by amino, glycidoxy or mercapto radicals 
and the like; and 
(ii) at least one C.sub.1 -C.sub.3 alkoxy radical or a C.sub.3 -C.sub.6 
alkoxyalkyleneoxy radical bonded by a SiO bond to the silicon atom; and 
(c) an effective amount of a condensation catalyst. 
By "effective amount" of condensation catalyst is intended, for example, 
from about 0.1 to about 5% by weight and preferably about 0.25 to about 
2.5% by weight of at least one compound of a metal which is typically 
selected from among titanium, tin, zirconium and mixtures thereof. 
Tetraisopropoxytitanate and tetrabutoxytitanate are desirable, but others 
that are useful may be found in U.S. Pat. 4,111,890, the disclosure of 
which is hereby expressly incorporated herein by reference. 
It should be appreciated that the reactive organopolysiloxane materials 
prepared in accordance with the present invention may be curable by 
moisture alone. In such cases no photoinitiator need be present. 
In formulating useful dual curing compositions of the invention it is 
necessary to include in the formulation a moisture curing catalyst, such 
as a titanium catalyst, in the formulation. 
The dual curing compositions formulated in accordance with the invention 
also include a photoinitiator. Any known radical photoinitiator can be 
used as well as mixtures thereof without departing from the invention 
hereof. Sample photoinitiators include benzoin and substituted benzoin 
compounds, benzophenone, Michler's ketone dialkoxybenzophenones, 
dialkoxyacetophenones, and the like. Photoinitiators made compatible with 
silicones by binding photoinitiating groups to organosiloxane polymer 
backbones may also be used. 
The amount of photoinitiator used in the composition will typically be in 
the range of between about 0.1% and 5% of the composition. Depending on 
the characteristics of the particular photoinitiator, however, amounts 
outside of this range may be employed without departing from the invention 
so long as they perform the function of rapidly and efficiently initiating 
polymerization of the acrylic groups. In particular, higher percentages 
may be required if silicone bound photoinitiators are used with high 
equivalent weight per photoinitiating group. 
It should also be understood that while the photoinitiator is used as a 
separate ingredient, the formulations used in the inventive method are 
intended to include formulations in which photoinitiating groups are 
included on the backbone of the same organopolysiloxane polymer which 
includes the photo curing and alkoxy groups discussed above. Preferred 
photo curing groups which may be attached to the organopolysiloxane 
include acrylate, methacrylate and glycidoxy groups. 
The inventive compositions may also contain other additives, provided they 
do not interfere with UV and moisture curing mechanisms, such as 
expandable spheres useful to prepare foamed end products. 
The invention will be further illustrated by way of the following examples.

EXAMPLES 
Example 1 
In a 5 liter, 4-neck round bottom flask equipped with mechanical stirrer, 
heating mantle, sparge tube and thermometer was charged 2008 g of an 
.alpha.,.omega.-hydroxyl terminated polydimethylsiloxane (having a 
viscosity of 100 cps). The fluid was heated to a temperature of 85.degree. 
C. and sparged with nitrogen for a period of time of 45 minutes to remove 
any volatile components such as water and carbon dioxide. 
Acryloxypropyltrimethoxysilane ("APTMS", 248.3 g) was then slowly added to 
the reactor over a period of time of 10 minutes. Diethylhydroxylamine 
("DEHA", 0.113 g) and n-butyllithium in hexane solution (1.6M; 1.5 mL) 
were sequentially added to the reactor. The mixture was maintained at a 
temperature of 85.degree. C. under nitrogen sparge for a period of time of 
4 hours. 
A small quantity of the mixture was then withdrawn, and was mixed with 1.5% 
by weight of the photoinitiator, diethylacetophenone ("DEAP"). The 
material was placed in between 2 layers of polyethylene films with 1 mm 
thickness which are 0.075" apart. The films were held in a glass plate 
fixture. The material was cured by UV with an intensity of 75 mw/cm.sup.2 
for one minute on each side. The mixture UV cured to an elastomer with a 
Shore 00 Durometer of 30. The reaction mixture was further heated for an 
additional period of time of 2 hours at a temperature of 85.degree. C. 
with nitrogen sparge. 
A small quantity of the mixture was again tested for UV cure as described 
above, and was found to UV cure to an elastomer with a Shore 00 Durometer 
of 62. Dry ice (0.34 g) was then added to the reaction mixture to quench 
the catalyst. The mixture was vacuum stripped to remove volatile 
components. To the final reaction mixture was added 1.5% by weight of 
DEAP, and UV cured as described before to an elastomer with a Shore 00 
Durometer of 70. 
Example 2 
In a 30 gallon reactor equipped with mechanical stirrer, heating/cooling 
capability, bottom sparge tube and thermometer was charged 54.3 kilograms 
(89.2%) of an .alpha.,.omega.-hydroxyl-terminated polydimethylsiloxane 
(having a viscosity of 100 cps). The fluid was heated to a temperature of 
85.degree. C. and sparged with nitrogen for a period of time of 45 minutes 
to remove any volatile compounds such as water and carbon dioxide gas. A 
first addition of APTMS (6.09 kg/10.5%) was then added to the reactor and 
sparged with nitrogen for a period of time of 10 minutes. DEHA (3.0 
g/0.005%) and n-butyllithium in hexane solution (1.6M; 40.5 mL/0.045%) 
were sequentially added to the reactor. The mixture was maintained at a 
temperature of 85.degree. C. while reacting under a nitrogen sparge for a 
period of time of 3 hours. 
The second addition of APTMS (0.152 kg/0.25%) was then made to the reactor 
and the reaction was allowed to continue for a period of time of 1 hour. A 
small quantity of the mixture was then withdrawn and mixed with 1.5% by 
weight of DEAP. The material was placed in between 2 layers of 
polyethylene films with 1 mm thickness which are 0.075" apart. The films 
were held in a glass plate fixture. The material was cured by UV with an 
intensity of 75 mw/cm.sup.2 for one minute on each side. The mixture UV 
cured to an elastomer with a Shore 00 Durometer of 67. The reaction 
catalyst was then quenched with dry ice. The mixture was vacuum stripped 
for a period of time of 1 hour at a temperature of 85.degree. C. to remove 
all volatile components. To the final reaction mixture was added 1.5% by 
weight of DEAP and UV cured as described before to an elastomer with a 
Shore 00 Durometer of 73. 
Comparative Example 1 
In a 5 liter, 4-neck round bottom flask equipped with mechanical stirrer, 
heating mantle, sparge tube and thermometer was charged 2530 g of an 
.alpha.,.omega.-hydroxyl terminated polydimethylsiloxane (having a 
viscosity of 100 cps). The fluid was heated to a temperature of 50.degree. 
C. while sparging with nitrogen for a period of time of 45 minutes to 
remove any volatile compounds such as water and carbon dioxide gas. APTMS 
(321 g) was then added to the reactor while nitrogen sparging. After 10 
minutes, 1.28 g (1.6M; 1.9 mL) of n-butyllithium in hexane solution was 
added. The temperature was held at a temperature of 50C while reacting 
under a nitrogen sparge for a period of time of 4 hours. A small quantity 
of the mixture was then withdrawn and was mixed with 1.5% by weight of 
DEAP. The material was placed in between 2 layers of polyethylene films 
with 1 mm thickness which are 0.075" apart. The films were held in a glass 
plate fixture. The material was cured by UV with an intensity of 75 
mw/cm.sup.2 for one minute on each side. The mixture did not UV cure. 
A further 2.0 mL of n-butyl lithium in hexane solution (1.6M) was added to 
the mixture and allowed to react for an additional hour. A small quantity 
of the mixture was again tested for UV cure as described above and also 
did not cure. The nitrogen sparge was then terminated, the mixture was 
sealed close and left to react at room temperature over night. The mixture 
was again tested for UV cure as described above but still failed to cure. 
Comparative Example 2 
In a 5 liter, 4-neck round bottom flask equipped with mechanical stirrer, 
heating mantle, sparge tube and thermometer was charged 2406 g of an 
.alpha.,.omega.-hydroxyl terminated polydimethylsiloxane (having a 
viscosity of 100 cps). The fluid was heated to a temperature of 80.degree. 
C. and sparged with nitrogen for a period of time of 45 minutes to remove 
any volatile components such as water and carbon dioxide gas. APTMS (324 
g) was then added drop wise to the silanol fluid while also charging 3.7 g 
(5.4 mL) n-butyllithium in hexane solution (1.6M) into the mixture by a 
syringe. The mixture was heated for a period of time of 3 hours at a 
temperature of 80.degree. C. under nitrogen sparge. A small quantity of 
the mixture was then withdrawn, and mixed with 1.5% by weight of DEAP. The 
material was placed in between 2 layers of polyethylene films with 1 mm 
thickness which are 0.075" apart. The films were held in a glass plate 
fixture. The material was cured by UV with an intensity of 75 mw/cm.sup.2 
for one minute on each side. The mixture failed to UV cure. 
Comparative Example 3 
In a 5 liter, 4-neck round bottom flask equipped with mechanical stirrer, 
heating mantle, sparge tube and thermometer was charged 1821.4 g of an 
.alpha.,.omega.-hydroxyl terminated polydimethylsiloxane (having a 
viscosity of 100 cps). The fluid was heated to a temperature of 85.degree. 
C. with a nitrogen sparge for a period of time of 45 minutes to remove any 
volatile components such as water and carbon dioxide gas. APTMS (225.2 g) 
was then added to the silanol fluid and mixed for a period of time of 5 
minutes. DEHA (0.1 g) was then added to the mixture. The mixture was 
maintained at a temperature of 85.degree. C. with a nitrogen sparge and 
allowed to react for a period of time of 3 hours. A small quantity of the 
mixture was withdrawn and tested for UV cure by adding 1.5% by weight of 
DEAP. The material was placed in between 2 layers of polyethylene films 
with 1 mm thickness which are 0.075" apart. The films were held in a glass 
plate fixture. The material was cured by UV with an intensity of 75 
mw/cm.sup.2 for one minute on each side. This mixture failed to UV cure. 
The reaction mixture flask was further heated at a temperature of 
85.degree. C. for an additional period of time of 8 hours. A small 
quantity of the mixture was again tested for UV cure by the procedure 
describe above and was shown to cure to a soft elastomer with a Shore 00 
Durometer of about 35-40. As noted above, to be suitable for use, a Shore 
00 Durometer value of at least 50 is typical, though 70-80 is particularly 
desirable. Further heating of the reaction mixture at a temperature of 
85.degree. C. for an additional period of time of 24 hours with nitrogen 
sparge did not improve the UV cure of the mixture. 
Example 3 
In a 5 liter 4-neck round bottom flask equipped with mechanical stirrer, 
heating mantle, sparge tube and thermometer is charged 2272.1 g of an 
.alpha.,.omega.-hydroxyl terminated polydimethylsiloxane (having a 
viscosity of 750 cps). The fluid is heated to a temperature of 80.degree. 
C. with nitrogen sparge for a period of time of 1 hour to remove any 
volatile components such as water and carbon dioxide gas. APTMS (176.51 g) 
is then added to the fluid and the mixture is mixed for 5 minutes. DEHA 
(0.118 g) and n-butyllithium in hexane solution (1.6M; 1.06 mL) are then 
added to the mixture sequentially. The mixture is heated at a temperature 
of 80.degree. C. with nitrogen sparge for a period of time of 16 hours. 
Nitrogen sparge is then terminated A small amount of dry ice (about 0.35 
g) is added to the mixture and the mixture is further mixed for an 
additional period of time of 3 hours. The mixture is vacuum stripped for a 
period of time of 1 hour, and filtered to give 
.alpha.,.omega.-acryloxydimethoxysilyl terminated polydimethylsiloxane. 
As can be seen from the examples above, the catalyst system of the present 
invention and the process which utilizes the catalyst system can provide 
dual curing products containing rapidly polymerizing ethylenically 
unsaturated groups which could not be prepared in a reasonable time using 
otherwise known materials. This invention also allows using a minimum 
amount of excess silane as a capping agent, thereby improving the "tack" 
of the finished product. 
The true scope of the invention is measured by the claims.