Two component fast-curing-RTV adhesive sealant suitable for low-ratio packaging

The present invention provides for a two component room temperature vulcanizable silicone compositions wherein both components may be used in approximately equal weights or volumes thereby minimizing the effects of mixture ratio errors.

FIELD OF THE INVENTION 
The present invention relates to room temperature curable silicone 
compositions that are separately packaged and which cure upon mixing 
without requiring the presence of atmospheric moisture. 
BACKGROUND OF THE INVENTION 
The cure rate of conventional single-component room temperature 
vulcanizable (RTV) formulations are limited by the rate at which 
atmospheric moisture diffuses into the curing formulation. One practical 
method by which the cure rate has been increased is to divide the 
formulation into two components, each of which are separately stable, but 
which upon mixing in the appropriate ratio, cures rapidly to produce a 
polymer network having the desired properties. Such two-component 
formulations are effective because the curing catalyst has been isolated 
in a first package from the hydroxy-terminated (silanol terminated) 
polymer which also contains an approximately stoichiometric quantity of 
water in the second package. When it is desired to prepare a room 
temperature vulcanizable silicone, mixing of the two components from the 
first and second packages initiates cure of the RTV silicone. This mode of 
packaging precludes the use of silanol terminated polymer in the catalyzed 
component and also limits the proportions in which two-component 
formulations may be prepared resulting in the need to use small quantities 
of the catalyst containing component relative to the polymer containing 
component. 
These formulations are thus limited in their utility by the proportion of 
ingredients comprising each of the components. The first and major 
component of such two-part RTV formulations generally comprises a linear 
silanol polymer, both ends terminated by hydroxy (silanol) groups, and 
fillers. The second and minor component comprises crosslinking agents, 
adhesion promoters, plasticizing fluids and the cure catalyst. This 
results in the first component being mixed in a relatively high weight 
ratio of ten or fifteen to one relative to the weight of the second 
component. 
There are several disadvantages associated with this disparate weight ratio 
of the two components. In automated continuous mixing equipment, long 
static mixers are required and there are difficulties associated with 
uniformly distributing the minor catalyst containing component in the 
larger polymer containing component. These difficulties are aggravated if 
the mixing is done by hand to produce small quantities. 
Early work by Berridge, U.S. Pat. No. 2,843,555, showed that an RTV 
formulation comprising a hydroxy terminated silanol polymer, 
alkoxy-substituted silane crosslinking agents optionally containing 
mineral fillers remained stable and unchanged in viscosity until the 
formulation was intentionally cured by the addition of certain metal salts 
which catalyzed the self-condensation of the hydroxyl groups of the 
silanol or with the alkoxy groups of the crosslinking agent. More recently 
a composition has been disclosed that may be used either in one-component 
or two-component formulations (packaging). Fuijioka et al. in U.S. Pat. 
No. 5,300,611 disclose extending the minor catalyzed component by the 
addition of a trimethoxy endcapped silanol polymer. Because water is 
absent during storage, and because the crosslinker is compounded in the 
major component there is no reaction. Mixing the two components at a ten 
to one weight ratio yields a composition that cures as a classical 
one-component RTV. Because no water is incorporated into the silanol base 
component the composition does not cure as fast as those compositions 
where water has been specifically added. 
An ultra low modulus two-component silicone sealant as disclosed by Palmer 
et al., U.S. Pat. No. 5,246,980, comprises a first component containing a 
hydroxy endblocked polydiorganosiloxane base, non-reinforcing filler, 
plasticizing fluid, di-functional amido-silane and an aminoxysilane 
oligomer. The second component comprises a hydroxy endblocked 
polydiorganosiloxane base, non-reinforcing filler, plasticizing fluid, and 
a low molecular weight hydroxy endblocked polydiorganosiloxane. The 
reactive amine functional silanes in the first component not only endcap 
the silanol polymer but also react with any water present in the 
formulation as adsorbed water on the filler. While this first component is 
shelf stable, it will cure by itself if exposed to a moist atmosphere. In 
contrast, the second component is inherently shelf stable and may be 
prepared without any particular precaution to exclude atmospheric 
moisture. Mixing both components together in a one to one weight ratio 
results in rapid deep section curing that does not require additional 
atmospherically supplied moisture to cure, producing an ultra low modulus 
silicone sealant. This particular sealant will cure to a non-flowing gel 
in three hours or less at 25.degree. C., reaching 35% of its ultimate 
cured properties in 24 hours. A related invention, U.S. Pat. No. 5,290,826 
teaches the addition of water to the second component. However, the 
addition of water to this formulation apparently does not materially 
shorten the time required for the RTV to become a non-flowing gel. A 
significant drawback associated with the use of the di-functional 
amidosilane in both RTV formulations is that the modulus of the cured 
formulation is limited. An additional drawback associated with the use of 
the amidosilane is that endcapping and curing reactions release 
teratogenic N-alkyl amides of carboxylic acids, e.g. N-methylacetamide. 
A tin compound containing composition as one of the components in a 
two-component system containing the essential ingredients of a triorgano 
substituted diorganopolysiloxane, the reaction product of a 
bis-silyl-alkane containing at least two monovalent hydrocarbon radicals 
per molecule with a diorganotin diacarboxylate and an organosilicon 
compound containing at least one amino or imino group per molecule is 
disclosed by Schiller, EP 0,612,335 B1. Additionally, a filler and/or a 
bis-silyl-alkane containing at least three monovalent hydrocarbon radicals 
per molecule which are bonded to the silicon via oxygen and are optionally 
substituted by an alkoxy group or an oligomer thereof. 
A two-component fast-curing formulation prepared in various proportions 
ranging from 20:1 to 1:1 is disclosed by Mueller et al., EP 0,369,259 B1. 
The preferred ratio of components is 10:1 to 10:6. Component A of Mueller 
et al. is prepared from the reaction product of a difunctional silanol and 
a molar excess of an oximosilane crosslinking agent and optionally 
plasticizing oil, filler, dyes, catalysts, stabilizers, primers and 
emulsifiers; component B of Mueller et al. contains, as a minimum, 
hydroxyl substituted silanol polymer and water. 
It is thus desirable to be able to provide a general method for the 
preparation of two-component RTV formulations in which each component is 
independently shelf stable and can be mixed with each other in a one to 
one weight or volume basis. It is also desirable to be able to vary the 
composition of both components in such a fashion that a wide variety of 
finished RTV products varying from extremely high strength to low modulus 
and hardness while maintaining a usable viscosity in the uncured 
components. It would also be desirable to be able to formulate the RTV 
components such that atmospheric moisture was not necessary to complete a 
rapid cure reaction, i.e. a cure achieving green strength within fifteen 
minutes and full cure within twenty-four hours. 
SUMMARY OF THE INVENTION 
The present invention thus provides for two part room temperature 
vulcanizable silicone compositions having approximately volumes. The 
present invention further provides for three different compositions that 
possess approximately equal volumes. These compositions vary by means of 
which component contains the cross linking compound. Alternatively both 
components may contain a cross linking compound which may be the same or 
different. 
The first composition provided for is a two part room temperature 
vulcanizable silicone composition consisting essentially of a catalyzed 
component, component (A), and a wet component, component (B); wherein 
component (A) comprises: 
(A)(1) 100 parts by weight of an alkoxy endcapped polydiorganosiloxane of 
formula 1: 
##STR1## 
where each R and R.sup.2 is independently a substituted or unsubstituted 
C.sub.1-15 monovalent hydrocarbon radical, R.sup.1 is a C.sub.1-8 
aliphatic organic radical selected from the group consisting of alkyl 
radicals, alkyl ether radicals, alkylketone radicals, alkylcyano radicals 
and C.sub.7-13 aralkyl radicals; n is a whole number ranging from about 50 
to 2500 and a is zero or one, having a viscosity ranging from about 100 to 
500,000 centipoise at 25.degree. C.; 
(A)(2) from 0.25 parts by weight to about 0.75 parts by weight per 100 
parts by weight of (A)(1), as described by formula 1, of a condensation 
curing catalyst; and 
(C)(1) from slightly greater than zero to about 5 parts by weight per 100 
parts of polymer (A)(1), as described by formula 1, of a polyalkoxysilane 
crosslinking agent of formula 2: 
EQU (R.sup.3 O).sub.4-a --Si--R.sup.4.sub.a ( 2) 
where R.sup.3 and R.sup.4 are independently substituted or unsubstituted 
C.sub.1-15 monovalent hydrocarbon radicals, R.sup.3 is a C.sub.1-8 
aliphatic organic radical selected from the group consisting of alkyl 
radicals, alkyl ether radicals, alkylketone radicals, alkylcyano radicals 
and C.sub.7-13 aralkyl radicals and a is zero or one; and wherein 
component (B) comprises: 
(B)(1) 100 parts by weight of a di silanol endstopped polydiorganosiloxane 
of formula 3: 
##STR2## 
where each R is independently a substituted or unsubstituted C.sub.1-15 
monovalent hydrocarbon radical selected from the group consisting of alkyl 
radicals, alkyl ether radicals, alkylketone radicals, alkylcyano radicals 
and C.sub.7-13 aralkyl radicals; m is a whole number ranging from about 50 
to 2500 having a viscosity ranging from about 100 to 500,000 centipoise at 
25.degree. C.; wherein the ratio of the volume of component (A) to the 
volume of component (B) ranges from about 4 volumes of component (A) to 
about 1 volume of component (B) to about 1 one volume of component (A) to 
about 4 volumes of component (B). 
The second composition provided for is a two part room temperature 
vulcanizable silicone composition consisting essentially of a catalyzed 
component, component (A), and a wet component, component (B); wherein 
component (A) comprises: 
(A)(1) 100 parts by weight of an alkoxy endcapped polydiorganosiloxane of 
formula 1: 
##STR3## 
where each R and R.sup.2 is independently a substituted or unsubstituted 
C.sub.1-15 monovalent hydrocarbon radical, R.sup.1 is a C.sub.1-8 
aliphatic organic radical selected from the group consisting of alkyl 
radicals, alkyl ether radicals, alkylketone radicals, alkylcyano radicals 
and C.sub.7-13 aralkyl radicals; n is a whole number ranging from about 50 
to 2500 and a is zero or one, having a viscosity ranging from about 100 to 
500,000 centipoise at 25.degree. C.; 
(A)(2) from 0.25 parts by weight to about 0.75 parts by weight per 100 
parts by weight of (A)(1), as described by formula 1, of a condensation 
curing catalyst; and 
wherein component (B) comprises: 
(B)(1) 100 parts by weight of a di silanol endstopped polydiorganosiloxane 
of formula 3: 
##STR4## 
where each R is independently a substituted or unsubstituted C.sub.1-15 
monovalent hydrocarbon radical selected from the group consisting of alkyl 
radicals, alkyl ether radicals, alkylketone radicals, alkylcyano radicals 
and C.sub.7-13 aralkyl radicals; m is a whole number ranging from about 50 
to 2500 having a viscosity ranging from about 100 to 500,000 centipoise at 
25.degree. C.; 
(C)(1) from slightly greater than zero to about 5 parts by weight per 100 
parts of polymer (B)(1), as described by formula 3, of a polyalkoxysilane 
crosslinking agent of formula 2: 
EQU (R.sup.3 O).sub.4-a --Si--R.sup.4.sub.a ( 2) 
where R.sup.3 and R.sup.4 are independently substituted or unsubstituted 
C.sub.1-15 monovalent hydrocarbon radicals, R.sup.3 is a C.sub.1-8 
aliphatic organic radical selected from the group consisting of alkyl 
radicals, alkyl ether radicals, alkylketone radicals, alkylcyano radicals 
and C.sub.7-13 aralkyl radicals and a is zero or one; 
wherein the ratio of the volume of component (A) to the volume of component 
(B) ranges from about 4 volumes of component (A) to about 1 volume of 
component (B) to about 1 one volume of component (A) to about 4 volumes of 
component (B). 
The third composition provided for is a two part room temperature 
vulcanizable silicone composition consisting essentially of a catalyzed 
component, component (A), and a wet component, component (B); wherein 
component (A) comprises: 
(A)(1) 100 parts by weight of an alkoxy endcapped polydiorganosiloxane of 
formula 1: 
##STR5## 
where each R and R.sup.2 is independently a substituted or unsubstituted 
C.sub.1-15 monovalent hydrocarbon radical, R.sup.1 is a C.sub.1-8 
aliphatic organic radical selected from the group consisting of alkyl 
radicals, alkyl ether radicals, alkylketone radicals, alkylcyano radicals 
and C.sub.7-13 aralkyl radicals; n is a whole number ranging from about 50 
to 2500 and a is zero or one, having a viscosity ranging from about 100 to 
500,000 centipoise at 25.degree. C.; 
(A)(2) from 0.25 parts by weight to about 0.75 parts by weight per 100 
parts by weight of (A)(1), as described by formula 1, of a condensation 
curing catalyst; and 
(A)(6) from slightly greater than zero to about 5 parts by weight per 100 
parts of polymer (A)(1), as described by formula 1, of a polyalkoxysilane 
crosslinking agent of formula 2: 
EQU (R.sup.3 O).sub.4-a --Si--R.sup.4.sub.a ( 2) 
where R.sup.3 and R.sup.4 are independently substituted or unsubstituted 
C.sub.1-15 monovalent hydrocarbon radicals, R.sup.3 is a C.sub.1-8 
aliphatic organic radical selected from the group consisting of alkyl 
radicals, alkyl ether radicals, alkylketone radicals, alkylcyano radicals 
and C.sub.7-13 aralkyl radicals and a is zero or one; 
wherein component (B) comprises: 
(B)(1) 100 parts by weight of a di silanol endstopped polydiorganosiloxane 
of formula 3: 
##STR6## 
where each R is independently a substituted or unsubstituted C.sub.1-15 
monovalent hydrocarbon radical selected from the group consisting of alkyl 
radicals, alkyl ether radicals, alkylketone radicals, alkylcyano radicals 
and C.sub.7-13 aralkyl radicals; m is a whole number ranging from about 50 
to 2500 having a viscosity ranging from about 100 to 500,000 centipoise at 
25.degree. C.; 
(B)(5) from slightly greater than zero to about 5 parts by weight per 100 
parts of polymer (B)(1), as described by formula 3, of a polyalkoxysilane 
crosslinking agent of formula 2: 
EQU (R.sup.3 O).sub.4-a --Si--R.sup.4.sub.a ( 2) 
where R.sup.3 and R.sup.4 are independently substituted or unsubstituted 
C.sub.1-15 monovalent hydrocarbon radicals, R.sup.3 is a C.sub.1-8 
aliphatic organic radical selected from the group consisting of alkyl 
radicals, alkyl ether radicals, alkylketone radicals, alkylcyano radicals 
and C.sub.7-13 aralkyl radicals and a is zero or one; 
wherein the ratio of the volume of component (A) to the volume of component 
(B) ranges from about 4 volumes of component (A) to about 1 volume of 
component (B) to about 1 one volume of component (A) to about 4 volumes of 
component (B). 
DETAILED DESCRIPTION OF THE INVENTION 
This invention relates to compositions of two-component formulations of 
silicone rubber, mixed in low ratio of components from which, the 
resulting mixture is capable of rapid cure and excellent adhesion to a 
wide variety of substrates. More specifically, the invention relates to 
formulations in which the components can be mixed in an approximately 1:1 
volume ratio thereby minimizing the effects of mixture-ratio errors on the 
properties of the final formulation and easing application from hand held 
cartridges and allowing applicators an easy visual method of monitoring 
the mix ratio by monitoring the relative amounts of movement of the 
follower plates used to pump the sealant components. 
As a result, the mixing ratio in accordance with the present invention 
provides major improvements in productivity when both components are 
pumped from drums of equal size using equivalent equipment in that it is 
particularly convenient to be able to visually monitor progress of the 
follower plates of each pair of dispensing pumps to verify delivery of the 
desired 1:1 ratio. Such a mixing ratio also provides major improvements in 
the consistency of the final mixture of the two-components by minimizing 
the effect of mixture ratio on the properties of the final formulation 
allowing substantial malfunction of dispensing equipment before the 
integrity of the cured sealant will suffer. 
I now disclose a method of packaging conventional catalysts in a stable 
formulation containing hetero-organo-endcapped silanol polymer which 
allows much greater flexibility in the ratio of wet to catalyzed 
components than in the conventional two-component technologies. This 
invention also allows for the ratio of wet component to catalyzed 
component to be much closer to one to one. The 1:1 ratio is highly 
desirable in the marketplace and is thus a primary feature of this 
disclosure. 
The two-component package of the present invention is comprised of a wet 
component and a catalyzed component which are each unto themselves a 
shelf-stable formulation. These two components, when mixed in an 
approximately 1:1 volumetric ratio, provide the correct blend of 
polymer(s), crosslinkers, filler(s), additive(s) and appropriate 
catalyst(s) to form a well cured polydimethylsiloxane crosslinked, filled 
network with good mechanical properties useful in most applications in 
which conventional one-component RTV cured formulations are known to be 
applicable. The wet component of the present invention is comprised of: 
polydimethyldisilanol(s); 
reinforcing and/or non-reinforcing filler(s); 
PDMS or organic plasticising fluids; 
alkoxy silane crosslinking reagents; 
sufficient water to allow rapid and complete cure of the siloxane network; 
and 
specialty additives specific to the performance of the final formulation. 
The catalyzed component of the present invention is comprised of: 
hetero-organo-endcapped silanol polymer(s); 
reinforcing and/or non-reinforcing filler(s); 
PDMS or organic plasticising fluids; 
alkoxy silane crosslinking reagents; 
any of the conventional one-component RTV catalyst known to promote 
condensation of silanol and/or hetero-organo-endcapped silanol polymers; 
and 
specialty additives specific to the performance of the final formulation. 
A two-component RTV formulated such that each component is a shelf-stable 
package unto itself, each containing a portion, in a small ratio of about 
4 to 1:1, preferably 2 to 1:1 and most preferably 1:1, of the ingredients 
required to prepare the final desired formulation. The final formulation 
contains sufficient ingredients to allow full curing of the formulation in 
the absence of atmospheric moisture and sufficient catalyst such that said 
cure rate may be designed into each two-component package so as to meet 
the requirements of many applications requiring from extremely rapid to 
quite slow cure rates. An alternate form of the invention can be one in 
which the water level incorporated into the wet component is insufficient 
to provide full cure but substantial to allow rapid skin-over followed by 
completion of the cure by conventional one-component cure technology. 
Due to the wide range of polymer molecular weight, type and level of 
fillers and crosslinking agents as well as specialty additives, this 
invention can be utilized to prepare a wide variety of formulations that 
cure to afford a wide range of properties in the resultant cured rubber. 
Specifically, such 2-component, RTV sealants are obtained by preparing two 
distinct and separate components: catalyzed and wet. The catalyzed 
component, component (A) is obtained by mixing, usually in a high shear 
continuous or batch process the following sub-components. 
(A)(1) 100 parts by weight of an alkoxy endcapped polydiorganosiloxane of 
formula 1: 
##STR7## 
where each R and R.sup.2 is independently a substituted or unsubstituted 
C.sub.1-15 monovalent hydrocarbon radical, R.sup.1 is a C.sub.1-8 
aliphatic organic radical selected from alkyl radicals, alkyl ether 
radicals, alkylketone radicals, alkylcyano radicals or a C.sub.7-13 
aralkyl radical; n is a whole number ranging from about 50 to 2500 and a 
is zero or one. The viscosity range of the polymer of formula 1 is from 
about 100 to 500,000 centipoise (cps.), preferably from about 500 to about 
300,000 cps. and most preferably is from about 10,000 to 150,000 cps. 
measured at 25.degree. C. The terminal silicon atom of the polymer must 
have at least two alkoxy groups and can have as many as three alkoxy 
groups in accordance with formula 1. 
(A)(2) From 0.25 parts by weight to about 0.75 parts by weight, preferably 
from about 0.3 to 0.6 parts by weight and most preferably from abut 0.35 
to 0.45 parts by weight, per 100 parts of polymer described by formula 1, 
sub-component (A)(1), of a condensation curing catalyst. Suitable 
catalysts include, but are not limited to, dibutylstannicdiacetate, 
dibutylstannicdilaurate, dibutylstannisacetatelaurate, stannous 
2-ethylhexanoate, dimethylstannicdineodecanoate, tetra-n-butyltitanate, 
tetra-iso-propyltitanate, 
2,5-di-isopropoxy-bis(ethylacetoacetate)titanium, 1,3-di-hydroxypropane-(a 
cetoacetate)(ethylacetoacetate)titanium and partially chelated derivatives 
of these salts with chelating agents such as acetoacetic acid esters and 
.beta.-diketones. Any catalyst known in the art that is useful in 
facilitating the self-coupling reaction of silanols or 
hetero-organo-endcapped silanols or of the coupling between silanols and 
hetero-organo-endcapped silanols is a such a condensation curing catalyst. 
(A)(3) From about 10 to 40 parts by weight, preferably from about 12 to 
about 18 parts by weight and most preferably from about 14 to about 20 
parts by weight of a treated reinforcing fumed silica filler per 100 parts 
of polymer described by formula 1, sub-component (A)(1). 
(A)(4) From about zero to 100 parts by weight, preferably from 10 to 80 
parts by weight and most preferably from 15 to 25 parts by weight, per 100 
parts of a polymer described by formula 1, sub-component (A)(1), of a 
non-reinforcing filler selected from but not limited to a list of 
inorganic mineral compounds such as of alkali metal carbonates and 
sulfates, alkaline earth metal carbonates and sulfates, TiO.sub.2, 
Fe.sub.2 O.sub.3, ZnO, MgO, Al.sub.2 O.sub.3, Al(SO.sub.4).sub.3, 
SiO.sub.2, diatomaceous earth, and organic and siloxane resins. The filler 
may optionally be treated with a treating agent selected from a group 
consisting, but not limited to, calcium stearate, stearic acid and other 
salts of fatty acids. Type and degree of treatment allows modification of 
the modulus of the cured formulation and the flow characteristics of the 
uncured formulation. 
(A)(5) From about zero to about 35 parts by weight, preferably about 10 to 
25 and most preferably from 15 to 20 parts by weight per 100 parts of 
polymer described by formula 1, sub-component (A)(1) of a 
triorgano-endstopped diorganopolysiloxane having a viscosity of from 10 to 
5,000 cps., measured at 25.degree. C. where the organic substituents are 
monovalent hydrocarbon radicals, preferably containing from 1 to 8 carbon 
atoms. Such linear diorganosiloxane polymers are useful as plasticizers. 
Preferably, such plasticizers are free of silanol groups but may contain 
up to 500 parts per million, ppm, of silanol groups. It is also preferable 
that the organic substituent groups are methyl and the viscosity ranges 
from 15 to 1,000 cps. and most preferably from about 20 to 200 cps., 
measured at 25.degree. C. 
(A)(6) or (C)(1) From zero to about 5 parts by weight, preferably from 
about zero to 3.5 parts by weight and most preferably from about 1 to 2.5 
parts by weight per 100 parts of polymer described by formula 1, 
sub-component (A)(1) of a polyalkoxysilane crosslinking agent of formula 2 
: 
EQU (R.sup.3 O).sub.4-a --Si--R.sup.4.sub.a ( 2) 
where R.sup.3 and R.sup.4 are independently substituted or unsubstituted 
C.sub.1-15 monovalent hydrocarbon radicals, R.sup.3 is a C.sub.1-8 
aliphatic organic radical selected from alkyl radicals, alkyl ether 
radicals, alkylketone radicals, alkylcyano radicals or a C.sub.7-13 
aralkyl radical and a is zero or one. The preferred compounds within the 
scope of this invention include but are not limited to: 
vinyltrimethoxysilane, methyltrimethoxy silane, ethyltrimethoxy silane, 
tetramethoxysilane, tetraethoxy silane, tetra n-propoxy silane, tetra 
i-propoxy silane, tetra n-butoxy silane, tetra i-butoxy silane and their 
partially hydrolyzed and subsequently condensed derivatives. The silane of 
formula 2 may be added for several purposes including but not limited to: 
providing stability to the compositions, to cap any unreacted silanol 
groups on the silicone fluid and to act as an aid to adhesion. 
The wet component, component (B) is obtained by mixing: 
(B)(1) 100 parts by weight (parts by weight) of a di silanol endstopped 
polydiorganosiloxane of formula 3: 
##STR8## 
where each R is independently a substituted or unsubstituted C.sub.1-15 
monovalent hydrocarbon radical selected from but not limited to alkyl 
radicals, alkyl ether radicals, alkylketone radicals, alkylcyano radicals 
or a C.sub.7-13 aralkyl radical; m is a whole number ranging from about 50 
to 2500. The viscosity range of the polymer of Formula 1 is from about 100 
to 500,000 cps., preferably from about 500 to about 300,000 cps. and most 
preferably is from about 10,000 to 150,000 cps. measured at 25.degree. C. 
(B)(2) From about 0.02 to about 0.1 parts by weight, preferably from about 
0.03 to 0.08 parts by weight and most preferably from 0.04 to 0.06 parts 
by weight, per 100 parts of polymer described by formula 3, sub-component 
(B)(1), of water. 
(B)(3) From about zero to 40 parts by weight, preferably from about 10 to 
about 20 parts by weight and most preferably from about 12 to about 16 
parts by weight of a treated reinforcing fumed silica filler per 100 parts 
of polymer described by formula 3, sub-component (B)(1); 
(B)(4) From about zero to 100 parts by weight, preferably from 10 to 80 
parts by weight and most preferably from 15 to 25 parts by weight, per 100 
parts of polymer described by formula 3, sub-component (B)(1), of a 
non-reinforcing filler selected from but not limited to a list of 
inorganic mineral compounds such as carbonates and sulfates of alkali and 
alkali earth metals, and oxides of transition metals such as CaCO.sub.3, 
TiO.sub.2, Fe.sub.2 O.sub.3, ZnO, MgO, Al.sub.2 O.sub.3 (possibly 
hydrated, Al(SO.sub.4).sub.3), quartz and organic or siloxane resins, 
diatomacious earth, etc. The filler may optionally be treated with a 
treating agent selected from a group consisting, but not limited to, 
calcium stearate, stearic acid and other salts of fatty acids. Type and 
degree of treatment allows modification of the modulus of the cured 
formulation and the flow characteristics of the uncured formulation. 
(B)(5) or (C)(1) From zero to about 5 parts by weight, preferably from 
about 1 parts by weight to 3.5 parts by weight and most preferably from 
abut 1.5 to 2.5 parts by weight, per 100 parts of polymer described by 
formula 3, sub-component (B)(1), of a polyalkoxysilane crosslinking agent 
of formula 2: 
EQU (R.sup.3 O).sub.4-a --Si--R.sup.4.sub.a ( 2) 
where R.sup.1, R.sup.2 and a are as previously defined. The preferred 
compounds within the scope of this invention include but are not limited 
to: vinyltrimethoxysilane, methyltrimethoxy silane, ethyltrimethoxy 
silane, tetramethoxysilane, tetraethoxy silane, tetra n-propoxy silane, 
tetra i-propoxy silane, tetra n-butoxy silane, tetra i-butoxy silane and 
their partially hydrolyzed and subsequently condensed derivatives. 
It is to be noted that the cross linking compounds, component (A)(6) and 
(B)(5) have been alternatively designated (C)(1). One of either component 
(A) or (B) must contain a crosslinking compound. Alternatively both 
components may contain a cross linking compound which may be the same or 
different. 
Conventional additives such as pigments, heat stability additives, adhesion 
promoters etc. may be present in either or both components so long as they 
do not interfere with the cure chemistry. 
The unique and unexpected result conferred by these particular formulations 
is that by choosing these specific classes of polymers, the volumes of the 
two components are approximately equal. By approximately equal, Applicant 
defines the volumetric ratio of the two components to be from about 4 
parts by volume of component (A) to about 1 part by volume of component 
(B) or alternatively from about 4 parts by volume of component (B) to 
about 1 part by volume of component (A), preferably be from about 3 parts 
by volume of component (A) to about 1 part by volume of component (B) or 
alternatively 3 parts by volume of component (B) to about 1 part by volume 
of component (A), more preferably be from about 2 parts by volume of 
component (A) to about 1 part by volume of component (B) or alternatively 
2 parts by volume of component (B) to about 1 part by volume of component 
(A), and most preferably be from about 1 part by volume of component (A) 
to about 1 part by volume of component (B) or alternatively 1 part by 
volume of component (B) to about 1 part by volume of component (A). 
Because the use of these specific polymers enables the use of two 
component room temperature vulcanizable silicone compositions in volume 
ratios of the two components that are below ten to one, it is the sense of 
Applicant's invention that two component room temperature vulcanizable 
compositions that utilize these compositions in volume ratios less than 
ten to one are essentially equivalent to Applicant's invention. It is to 
be noted that while each component is present in an approximately equal 
volumetric amount, the amounts of additional sub-components in each 
component are based on 100 parts by weight of polymer (A)(1) in component 
(A) and 100 parts by weight of polymer (B)(1) in component (B). Thus when 
additional sub-components are recited in the appended claims, the weight 
of the sub-component is added to that of the respective base polymer, 
(A)(1) for component (A) or (B)(1) for component (B). 
Many substrates can be bonded with other substrates using the silicone 
rubber of the present invention. Such substrates are exemplified by 
inorganic substrates such as glass, ceramic, porcelain, cement, mortar, 
concrete, natural stone, etc.; by metal substrates such as copper, 
aluminum, iron, steel, stainless steels, etc.; by organic polymer resins 
such as polyarylate, polyamide, polyimide, polycarbonate, polyacrylate, 
polymethacrylate, polystyrene, polyester, polybutylene, phenolic, epoxy, 
polybutylene terephthalate, polyphenylene oxide, by blends of the 
aforementioned resins such as polyphenylenesulfide, 
acrylonitrile/butadiene/styrene copolymer, etc.; by rubbers such as 
natural rubber, synthetic rubber, silicone rubber, etc.

EXPERIMENTAL 
So that those skilled in the art can understand the present invention, the 
following examples are presented, it being understood that these examples 
are illustrative only and should not limit the scope of the invention in 
the appended claims. The composition of formulations shown in examples are 
measured in parts by weight, measured at 23.+-.3.degree. C. unless 
otherwise specified. Components were mixed in either: a stirred-tank 
reactor; a dough mixer; a Semco.TM. mixing, storage and dispensing tube 
with a Semkit mixing system, dual dispensing tubes forcing a fixed ratio 
of components into the head of a static mixing tube or on a 30 mm 
Werner-Pfleiderer counter-rotating twin-screw extruder. 
Reference Example 1 
Preparation of a Wet Base in a Stirred-tank Reactor 
40 parts by weight of calcium carbonate was added to a stirred-tank 
reactor; to this was added with agitation, 100 parts by weight of silanol, 
3,000 cps., 3 parts by weight of partially hydrolyzed and subsequently 
condensed tetraethoxysilane, (dp about 5) and 0.07 parts by weight of 
water. 
Reference Example 2 
Preparation of a Wet Base in a Dough Mixer 
41.4 parts by weight treated fumed silica was blended with 100 parts by 
weight of silanol, 30,000 cps., 42.9 parts by weight of 
mono-t-butoxy-endcapped silanol, 3,000 cps., 2.6 parts by weight of low 
molecular weight silanol with a dp of ca. 5, 0.77 parts by weight of 
titanium dioxide and 38.5 parts by weight of fully 
trimethylsiloxy-endcapped silanol, 20 cps. 
Reference Example 3 
Preparation of a Wet Base in a Semkit.TM. Mixer 
Equal portions of the formulations described in Reference Example 1 and 
Reference Example 2 were mixed in a Semkit.TM. mixer for 15 minutes. 
Reference Example 4 
Preparation of a Wet Base in a Semkit.TM. Mixer 
420 g of the formulations described in Reference Example 1, 202 g of the 
formulations described in Reference Example 2 and 6.6 g of 
aminoethylaminopropyltrimethoxysilane were mixed in a Semkit.TM. mixer for 
15 minutes. Within 1 hour, viscosity in the formulation began to build 
substantially. 
Reference Example 5 
Preparation of a Wet Base in a Semkit.TM. Mixer 
405 g of the formulations described in Reference Example 1 and 212 g of the 
formulations described in Reference Example 2 were mixed in a Semkit.TM. 
mixer for 15 minutes. 
Reference Example 6 
Preparation of a Dry Base in the Werner-Pfleiderer Extruder 
60 parts by weight of silanol, 30,000 cps. and 40 parts by weight of 
silanol, 3,000 cps., were mixed with 13.64 parts by weight of D.sub.4 
treated fumed silica in a Werner-Pfleiderer extruder beginning at 
75.degree. C. and cooled to 25.degree. C. at the outlet. 
Reference Example 7 
Preparation of a Wet Base in a Semkit.TM. Mixer 
405 g of the formulations described in Reference Example 1 and 212 g of the 
formulations described in Reference Example 6 were mixed in a Semkit.TM. 
mixer for 15 minutes. 
Reference Example 8 
Preparation of a Catalyzed Component in the Werner-Pfleiderer Extruder 
In the Werner-Pfleiderer extruder, 17 parts by weight of D.sub.4 treated 
fumed silica was sheared into 100 parts by weight of 
methyldimethoxy-terminated silanol polymer, 100,000 cps, and this paste 
was diluted with 20 parts by weight trimethylsilyl-endcapped silanol 
polymer composed solely of D units and 6.4 parts by weight of 
trimethylsilyl-endcapped silanol polymer composed of mostly D units with a 
small incorporation of T units; 2.3 parts by weight of 
hexamethyldisilazane, 1.6 parts by weight 
aminoethylaminopropyltrimethoxysilane, 0.45 parts by weight 
methyltrimethoxysilane, 0.4 parts by weight dibutylstannicdiacetate, and 
4.5 parts by weight of a blue pigment blend in trimethylsilyl-endcapped 
silanol polymer composed solely of D units with a viscosity of about 
10,000 cps. 
Reference Example 9 
Preparation of a Catalyzed Component in the Werner-Pfleiderer Extruder 
In the Werner-Pfleiderer extruder, 18.5 parts by weight of D.sub.4 treated 
fumed silica was sheared into 100 parts by weight of 
methyldimethoxy-terminated silanol polymer, 100,000 cps, and this paste 
was diluted with 20 parts by weight trimethylsilyl-endcapped silanol 
polymer composed solely of D units and 10.8 parts by weight of 
trimethylsilyl-endcapped silanol polymer composed of mostly D units with a 
small incorporation of T units; 2.3 parts by weight of 
hexamethyldisilazane, 1.5 parts by weight 
aminoethylaminopropyltrimethoxysilane, 0.46 parts by weight 
methyltrimethoxysilane and 0.4 parts by weight dibutylstannicdiacetate. 
Reference Example 10 
Preparation of a Catalyzed Component in the Werner-Pfleiderer Extruder 
In the Werner-Pfleiderer extruder, 18.5 parts by weight of D.sub.4 treated 
fumed silica was sheared into 100 parts by weight of 
methyldimethoxy-terminated silanol polymer, 100,000 cps, and this paste 
was diluted with 20 parts by weight trimethylsilyl-endcapped silanol 
polymer composed solely of D units and 10.8 parts by weight of 
trimethylsilyl-endcapped silanol polymer composed of mostly D units with a 
small incorporation of T units; 2.3 parts by weight of 
hexamethyldisilazane, 1.5 parts by weight 
aminoethylaminopropyltrimethoxysilane, 0.46 parts by weight 
methyltrimethoxysilane and 0.4 parts by weight dibutylstannicdiacetate. 
Reference Example 11 
Preparation of a Catalyzed Component in the Werner-Pfleiderer Extruder 
In the Werner Pfleiderer extruder, 17 parts by weight of D.sub.4 treated 
fumed silica was sheared into 100 parts by weight of 
methyldimethoxy-terminated silanol polymer, 100,000 cps, and this paste 
was diluted with 20 parts by weight trimethylsilyl-endcapped silanol 
polymer composed solely of D units and 6.4 parts by weight of 
trimethylsilyl-endcapped silanol polymer composed of mostly D units with a 
small incorporation of T units; 2.3 parts by weight of 
hexamethyldisilazane, 1.6 parts by weight 
aminoethylaminopropyltrimethoxysilane, 0.45 parts by weight 
methyltrimethoxysilane and 0.4 parts by weight dibutylstannicdiacetate. 
Reference Example 12 
Preparation of a Catalyzed Component in the Werner-Pfleiderer Extruder 
In the Werner-Pfleiderer extruder, 17.1 parts by weight of D.sub.4 treated 
fumed silica was sheared into 100 parts by weight of 
methyldimethoxy-terminated silanol polymer, 30,000 cps, and this paste was 
diluted with 14.3 parts by weight trimethylsilyl-endcapped silanol polymer 
composed solely of D units and 5 parts by weight of 
trimethylsilyl-endcapped silanol polymer composed of mostly D units with a 
small incorporation of T units; 2.9 parts by weight of 
hexamethyldisilazane, 1.45 parts by weight 
aminoethylaminopropyltrimethoxysilane, 0.7 parts by weight 
methyltrimethoxysilane and 0.3 parts by weight dibutylstannicdiacetate. 
Reference Example 13 
Preparation of a Catalyzed Component in the Werner-Pfleiderer Extruder 
In the Werner-Pfleiderer extruder, 18.5 parts by weight of D.sub.4 treated 
fumed silica was sheared into 100 parts by weight of 
methyldimethoxy-terminated silanol polymer, 30,000 cps, and this paste was 
diluted with 7.7 parts by weight trimethylsilyl-endcapped silanol polymer 
composed solely of D units and 10.8 parts by weight of 
trimethylsilyl-endcapped silanol polymer composed of mostly D units with a 
small incorporation of T units and 2.3 parts by weight of 
hexamethyldisilazane. 
Reference Example 14 
Preparation of a Catalyzed Component in the Werner-Pfleiderer Extruder 
In the Werner-Pfleiderer extruder, 18.5 parts by weight of D.sub.4 treated 
fumed silica was sheared into 100 parts by weight of 
methyldimethoxy-terminated silanol polymer, 30,000 cps, and this paste was 
diluted with 22.3 parts by weight trimethylsilyl-endcapped silanol polymer 
composed solely of D units and 5.4 parts by weight of 
trimethylsilyl-endcapped silanol polymer composed of mostly D units with a 
small incorporation of T units. 
Reference Example 15 
Preparation of a Wet Base in a Semkit.TM. Mixer 
405 g of the formulations described in Reference Example 1, 211 g of the 
formulations described in Reference Example 2 were mixed in a Semkit.TM. 
mixer for 5 minutes. 
Reference Example 16 
Preparation of a Catalyzed Component in a Semkit.TM. Mixer 
575 g of the formulations described in Reference Example 12 and 0.6 g of 
dibutylstannicdiacetate were mixed in a Semkit.TM. mixer for 10 minutes. 
Example 1 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 75 g of the formulation described in Reference Example 
3 was mixed with 75 g of the formulation described in Reference Example 8 
during about one minute; the formulation was cast into a 4" by 5" 
Teflon.TM. mold about 0.075" deep and allowed to cure at 23.+-.2.5.degree. 
C. and 50.+-.5% relative humidity for six days. Cure was evident soon 
after casting the formulation as the formulation was tack-free within 5 
minutes. Physical testing data for this formulation is shown in Table B. 
Example 2 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 75 g of the formulation described in Reference Example 
6 was mixed with 75 g of the formulation described in Reference Example 8 
during about one minute; the formulation was cast into a 4" by 5" 
Teflon.TM. mold about 0.075" deep and allowed to cure at 23.+-.2.5.degree. 
C. and 50.+-.5% relative humidity for six days. Four hours after casting 
the formulation was still tacky; after 24 hours, the sheet felt cured. 
Physical testing data for this formulation is shown in Table B. 
Example 3 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, the formulation of Example 1 was duplicated. Shear 
analysis specimens from production line window segments were assembled 
during the next four minutes. Cure was evident soon after assembly of the 
first four specimens. Shear analysis data is presented as a function of 
time after mixing ingredients in Table A. 
Example 4 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 40 g of the formulation described in Reference Example 
5 was mixed, during about one minute, with 40 g of the formulation 
described in Reference Example 11, to which the level of 
aminoethylaminopropyltrimethoxysilane had been doubled. Shear analysis 
specimens from production line window segments were assembled during the 
next four minutes. Cure was evident soon after assembly of the first four 
specimens. Shear analysis data is presented as a function of time after 
mixing ingredients in Table A. 
TABLE A 
______________________________________ 
Example Elapsed Time 
No. Specimen (min/hour) 
Shear Strength (psi) 
______________________________________ 
Ex 3 A 15 min 2.9 
B 30 min 3.4 
C 60 min 4.5 
D 120 min 5.6 
Ex 4 A 15 min 3.0 
B 30 min 5.6 
C 60 min 11.8 
D 2 hours 16.4 
E 18 hours 47.3 
F 24 hours 42.1 
G 24 hours 48.7 
______________________________________ 
Example 5 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 101 g of the formulation described in Reference 
Example 5 was mixed with 68 g of the formulation described in Reference 
Example 11 during about three minutes; the formulation was cast into a 4" 
by 5 5" Teflon.TM. mold about 0.075" deep and allowed to cure at 
23.+-.2.5.degree. C. and 50.+-.5% relative humidity for six days. The 
surface of the sheets was slightly wavy--characteristic or a two-component 
formulation which was tooled after cross-linking had progressed 
significantly. Physical testing data for this formulation is shown in 
Table B. 
Comparative Example 5 
Preparation in a Static Mixer of a Catalyzed Formulation 
In a dual tube system, dispensing equal portions through a static mixing 
tube, of the formulations described in Reference Example 5 and Reference 
Example 8; the formulation was cast into a 4" by 5" Teflon.TM. mold about 
0.075" deep and allowed to cure at 23.+-.2.5.degree. C. and 50.+-.5% 
relative humidity. Cure was evident soon after casting the formulation as 
the formulation was tack-free within 5 minutes. Physical testing data for 
this formulation is shown in Table B. 
Example 6 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 75 g of the formulation described in Reference Example 
7 was mixed with 75 g of the formulation described in Reference Example 11 
during about one to two minutes; the formulation was cast into a 4" by 5" 
Teflon.TM. mold about 0.075" deep and allowed to cure at 23.+-.2.5.degree. 
C. and 50.+-.5% relative humidity for 19 hours. The surface of the sheets 
was slightly wavy as in Example 5. Physical testing data for this 
formulation is shown in Table B. 
Comparative Example 6 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
Cured RTV sheets formed from the formulation described in Example 6 were 
allowed to cure at 23.+-.2.5.degree. C. and 50.+-.5% relative humidity for 
seven days. Physical testing data for these sheets is shown in Table B. 
Example 7 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 75 g of the formulation described in Reference Example 
2 was mixed with 75 g of the formulation described in Reference Example 11 
during about one to two minutes; the formulation was cast into a 4" by 5" 
Teflon.TM. mold about 0.075" deep and allowed to cure at 23.+-.2.5.degree. 
C. and 50.+-.5% relative humidity for 13 days. After 24 hours, the sheet 
had not cured completely; sheets were removed from the mold after three 
days. Physical testing data for this formulation is shown in Table B. 
Example 8 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 75 g of the formulation described in Reference Example 
7 was mixed with 75 g of the formulation described in Reference Example 10 
during about one to two minutes; the formulation was cast into a 4" by 5" 
Teflon.TM. mold about 0.075" deep and allowed to cure at 23.+-.2.5.degree. 
C. and 50.+-.5% relative humidity for seven days. After 24 hours, the 
sheet had not cured completely; sheets were removed from the mold after 
three days. Physical testing data for this formulation is shown in Table 
B. 
TABLE B 
______________________________________ 
Hardness, 
Example 
Shore A Ultimate Tensile 
Ultimate 
No. durometer 
Strength (psi) 
Elongation (%) 
s @ 100% e 
______________________________________ 
Ex 1 23 318 346 92 
Ex 2 16.9 234 325 78 
Ex 5 23.5 255 254 94 
Comp 23.8 231 212 106 
Ex 6 24.6 234 221 92 
Comp 24.6 275 248 96 
Ex 7 18.5 387 485 73 
Ex 8 13.1 118.5 134 83 
______________________________________ 
Example 9 
Preparation in a Static Mixer of a Catalyzed Formulation 
Using a dual tube dispensing system, equal portions of the formulations 
described in Reference Example 15 and Reference Example 12 were dispensed 
into a static mixer; the resulting formulation was cast into a 4" by 5" 
Teflon.TM. mold about 0.075" deep and allowed to cure at 23.+-.2.5.degree. 
C. and 50.+-.5% relative humidity. Cure was evident soon after casting the 
formulation as the formulation was tack-free within 10 minutes. 
Example 10 
Preparation in a Static Mixer of a Catalyzed Formulation 
Using a dual tube dispensing system, equal portions of the formulations 
described in Reference Example 15 and Reference Example 16 were dispensed 
into a static mixer; the resulting formulation was cast into a 4" by 5" 
Teflon.TM. mold about 0.075" deep and allowed to cure at 23.+-.2.5.degree. 
C. and 50.+-.5% relative humidity. Cure was evident soon after casting the 
formulation as the formulation was tack-free within 5 minutes. 
Example 11 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 133 g of the formulation described in Reference 
Example 13, 9.0 g of trimethylsiloxy endcapped dimethylpolysiloxane, 
essentially free of silanol endgroups, 2.5 g of partially hydrolyzed and 
subsequently condensed tetraethoxy silane and 1.2 g 
dibutylstannicdiacetate was mixed with 60 g of the formulation described 
in Reference Example 1 during about one to two minutes; the formulation 
was cast into a 4" by 5" Teflon.TM. mold about 0.075" deep. Cure was 
rapid. The sheet was removed from the mold after 24 hours and allowed to 
cure at 23.+-.2.5.degree. C. and 50.+-.5% relative humidity for seven 
days. Physical data for the sheet is reported in Table C. 
Comparative Example 11 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 102 g of the formulation described in Reference 
Example 13, 9.0 g of trimethylsiloxy endcapped dimethylpolysiloxane, 
essentially free of silanol endgroups, 2.1 g of partially hydrolyzed and 
subsequently condensed tetraethoxy silane and 1.2 g 
dibutylstannicdilaurate was mixed with 90 g of the formulation described 
in Reference Example 1 during about one to two minutes; the formulation 
was cast into a 4" by 5" Teflon.TM. mold about 0.075" deep. Cure was 
rapid. The sheet was removed from the mold after 24 hours and allowed to 
cure at 23.+-.2.5.degree. C. and 50.+-.5% relative humidity for seven 
days. Physical data for the sheet is reported in Table C. 
Comparative Example 11a 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 133 g of the formulation described in Reference 
Example 13, 9.0 g of trimethylsiloxy endcapped dimethylpolysiloxane, 
essentially free of silanol endgroups, 2.5 g of partially hydrolyzed and 
subsequently condensed tetraethoxy silane and 1.2 g 
dibutylstannicdilaurate was mixed with 60 g of the formulation described 
in Reference Example 1 during about one to two minutes; the formulation 
was cast into a 4" by 5" Teflon.TM. mold about 0.075" deep. Cure was 
rapid. The sheet was removed from the mold after 24 hours and allowed to 
cure at 23.+-.2.5.degree. C. and 50.+-.5% relative humidity for seven 
days. Physical data for the sheet is reported in Table C. 
Example 12 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 120 g of the formulation described in Reference 
Example 13, 9.0 g of trimethylsiloxy endcapped dimethylpolysiloxane, 
essentially free of silanol endgroups, 3.8 g tetraethoxy silane and 0.4 g 
dibutylstannicdiacetate was mixed with 60 g of the formulation described 
in Reference Example 1 during about one to two minutes; the formulation 
was cast into a 4" by 5" Teflon.TM. mold about 0.075" deep. Cure was 
rapid. The sheet was removed from the mold after 24 hours and allowed to 
cure at 23.+-.2.5.degree. C. and 50.+-.5% relative humidity for seven 
days. Physical data for the sheet is reported in Table C. 
Example 13 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 124 g of the formulation described in Reference 
Example 14, 3.7 g of partially hydrolyzed and subsequently condensed 
tetraethoxy silane and 0.4 g dibutylstannicdiacetate was mixed with 60 g 
of the formulation described in Reference Example 1 during about one to 
two minutes; the formulation was cast into a 4" by 5" Teflon.TM. mold 
about 0.075" deep. Cure was rapid. The sheet was removed from the mold 
after 24 hours and allowed to cure at 23.+-.2.5.degree. C. and 50.+-.5% 
relative humidity for seven days. Physical data for the sheet is reported 
in Table C. 
Comparative Example 13 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 124 g of the formulation described in Reference 
Example 14, 3.7 g of tetraethoxy silane and 0.4 g dibutylstannicdiacetate 
was mixed with 60 g of the formulation described in Reference Example 1 
during about one to two minutes; the formulation was cast into a 4" by 5" 
Teflon.TM. mold about 0.075" deep. Cure was rapid. The sheet was removed 
from the mold after 24 hours and allowed to cure at 23.+-.2.5.degree. C. 
and 50.+-.5% relative humidity for seven days. Physical data for the sheet 
is reported in Table C. 
Example 14 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 94 g of the formulation described in Reference Example 
14, 3.7 g of partially hydrolyzed and subsequently condensed tetraethoxy 
silane and 0.4 g dibutylstannicdiacetate was mixed with 90 g of the 
formulation described in Reference Example 1 during about one to two 
minutes; the formulation was cast into a 4" by 5" Teflon.TM. mold about 
0.075" deep. Cure was rapid. The sheet was removed from the mold after 24 
hours and allowed to cure at 23.+-.2.5.degree. C. and 50.+-.5% relative 
humidity for seven days. Physical data for the sheet is reported in Table 
C. 
Comparative Example 14 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 94 g of the formulation described in Reference Example 
14, 3.7 g of tetraethoxy silane and 0.4 g dibutylstannicdiacetate was 
mixed with 90 g of the formulation described in Reference Example 1 during 
about one to two minutes; the formulation was cast into a 4" by 5" 
Teflon.TM. mold about 0.075" deep. Cure was rapid. The sheet was removed 
from the mold after 24 hours and allowed to cure at 23.+-.2.5.degree. C. 
and 50.+-.5% relative humidity for seven days. Physical data for the sheet 
is reported in Table C. 
Example 15 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 64 g of the formulation described in Reference Example 
14, 3.7 g of partially hydrolyzed and subsequently condensed tetraethoxy 
silane and 0.4 g dibutylstannicdiacetate was mixed with 120 g of the 
formulation described in Reference Example 1 during about one to two 
minutes; the formulation was cast into a 4" by 5" Teflon.TM. mold about 
0.075" deep. Cure was rapid. The sheet was removed from the mold after 24 
hours and allowed to cure at 23.+-.2.5.degree. C. and 50.+-.5% relative 
humidity for seven days. Physical data for the sheet is reported in Table 
C. 
Comparative Example 15 
Preparation in Semco.TM. Tubes of a Catalyzed Formulation 
In a Semco.TM. tube, 64 g of the formulation described in Reference Example 
14, 3.7 g of tetraethoxy silane and 0.4 g dibutylstannicdiacetate was 
mixed with 120 g of the formulation described in Reference Example 1 
during about one to two minutes; the formulation was cast into a 4" by 5" 
Teflon.TM. mold about 0.075" deep. Cure was rapid. The sheet was removed 
from the mold after 24 hours and allowed to cure at 23.+-.2.5.degree. C. 
and 50.+-.5% relative humidity for seven days. Physical data for the sheet 
is reported in Table C. 
TABLE C 
______________________________________ 
Hardness, 
Example 
Shore A Ultimate Tensile 
Ultimate 
No. durometer 
Strength (psi) 
Elongation (%) 
s @ 100% e 
______________________________________ 
Ex 11 31.6 388 204 104 
Comp 26.5 189 134 128 
Comp 24.9 383 258 118 
Ex 12 35.2 237 149 135 
Ex 13 22.5 140 125 104 
Comp 21.6 228 196 92 
Ex 14 29.3 165 117 132 
Comp 28.9 189 139 123 
Ex 15 34.7 342 161 165 
Comp 36.6 278 146 159 
______________________________________