PROCESS FOR THE MANUFACTURE OF A ONE-COMPONENT ROOM TEMPERATURE VULCANIZABLE SILICONE COMPOSITION

METHODE DE FABRICATION D'UN COMPOSE AU SILICONE A ELEMENT UNIQUE VULCANISABLE A LA TEMPERATURE AMBIANTE D'UNE PIECE

English Abstract

ABSTRACT OF THE DISCLOSURE
A novel process is disclosed for the manufacture of
a one-component, room-temperature vulcanizable silicone
composition which comprises passing a silanol chain
stopped polydiorganosiloxane, a cross-linking silane and
a silanol reactive organometallic ester compound of a
metal through a devolatilizing extruder to form a one-
component, room-temperature vulcanizable silicone composition.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A process for the preparation of a fluid composition
that is stable under substantially anhydrous conditions and
curable to a self-bonding elastic solid in the presence of
moisture, said process comprising passing 100 parts by weight
of a silanol chain stopped polydiorganosiloxane of the
formula:
<IMG>
wherein R and R1 are each, independently, organic radicals of
up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl
and cyano lower alkyl and n is an average number of from about
10 to 15,000, from 0.01 to 5.0 parts by weight of a cross-
linking silane of the formula:
R2mSi(OR3)4-m
wherein R2 and R3 have the values defined for R and R1 herein-
above and m has a value of 0 to 3 and an average value based on

the total amount of silane in the composition of 0 to
1.99, and a silanol reactive organometallic ester
compound of a metal, said compound having radicals
attached to the metal atom, at least one of said
radicals being a hydrocarbonoxy radical or a substituted
hydrocarbonoxy radical, said radicals being attached
to the metal atoms through M-O-C linkages wherein M
is the metal and any remaining valences of the metal
are satisfied by substituents selected from organic
radicals which are attached to the metal atom through
M-O-C linkages, -OH and -O- of a M-O-M linkage, the
weight ratio of the silanol reactive organometallic
ester compound to the cross-linking silane always being
at least unity, through a devolatilizing extruder to
form a fluid composition that is curable to a self-
bonding elastic solid in the presence of moisture.
2. The process of claim 1 wherein a filler is
combined with the preblend of (a) and the silanol reactive
organometallic ester compound prior to extrusion.
3. The process of claim 2 wherein the total number
of the moles of cross-linking silane is less than the
total of the number of moles of the terminal silanol
groups in the polydiorganosiloxane.
21

4. The process of claim, 1 2 or 3 wherein the total
of the number of moles of silanol reactive ester linkages
in the organometallic ester compound is equal to or
greater than the total of the number of moles of terminal
silanol groups in the polydiorganosiloxane component.
5. A process as defined in claim 1 wherein the
weight ratio of the silanol reactive organometallic ester
compound of a metal to the cross-linking silane is from
1 to 50
6. A process as defined in claim 5 wherein the weight
ratio of the silanol reactive organometallic ester compound
of a metal to the cross-linking silane is from 1 to 5.
7. A process as defined in claim 1 wherein the
viscosity of the silanol chain-stopped polydiorganosiloxane
is within the range of 2,000 to 1,000,000 cups at 25°C.
8. A procerss as defined in claim 1 wherein, in the
silanol chain-stopped polydiorganosiloxane, at least 50%
of the total number of R and R1 groups are alkyl radicals
and any remaining groups are aryl radicals.
9 A process as defined in claim 1 wherein, in the
cross-linking silane, at least 50% of the total number of
R2 and R3 groups are alkyl radicals and any remaining
groups are aryl radicals and m is 1.
10. A process as defined in claim 8 or 9 wherein the
alkyl radicals are methyl radicals and any remaining aryl
radicals are phenyl radicals.
11.A process as defined in claim 1 wherein, in said
organometallic ester component, the metal M is selected
from lead, tin, zirconium, antimony, iron, cadmium, barium,
calcium titanium, bismuth, manganese, zinc, chromium, co-
bslt, nickel, aluminum, gallium or germanium.
12. A process as defined in claim 11 wherein the
22

organometallic ester component is an orthoester of a lower
aliphatic alcohol, a partially chelated ester of a lower
aliphatic alcohol with a .beta.-dicarbonyl compound or a partial
hydrolyzate of such compounds which retain at least one
hydrocarbonoxy radical or substituted hydrocarbonoxy radical
attached to the metal atom through M_O_C linkages.
13. A process as defined in claim 12 wherein said
organometallic ester component is a titanium chelate
catalyst of the formula:
<IMG>
or
<IMG>
wherein R4 is hydrogen, or an organic radical of up to 8
carbon atoms selected from hydrocarbyl, halohydrocarbyl, or
carboxyalkyl; R5 is a radical of up to 8 carbon atoms selected
from hydrocarbyl, halohydrocarbyl and cyano-lower alkyl; R6
is selected from same group as R4 and in addition from halo,
cyano, nitro, carboxy ester, or acyl and hydrocarbyl sub-
stituted by halo, cyano, nitro, carboxy ester and acyl, the
total number of carbon atoms in the R4 and in the R6 sub-
stituted alkanedioxy radical being not more than about 18; R7
23

is selected from hydrogen or an organic radical of up to 8
carbon atoms selected from hydrocarbyl, halohydrocarbyl, or
acyl and, when taken together with R5 forms together with
the carbon atoms to which they are attached a cyclic hydro-
carbon substituent of up to about 12 carbon atoms or such
a substituent substituted with one or more of a chloro,
nitro, acyl, cyano or carboxy ester substituents; X is a
radical of up to 20 carbon atoms selected from hydrocarbyl,
halohydrocarbyl, cyanoalkyl, alkoxy, haloalkoxy, cyanoalkoxy,
amino or ether and polyether groups of the formula
(CqH2qO)vR where q is from 2 to 4, v is from 1 to 20
and R is an organic radical of up to 8 carbon atoms selected
from hydrocarbyl, halohydrocarbyl or cyano lower alkyl, a
is O or an integer of up to 8 and, when a is 0, the
<IMG> groups are bonded to each other in a cyclic
fashion, and R8 is a radical of up to 8 carbon atoms selected
from hydrocarbyl, halohydrocarbyl or cyano-lower alkyl.
14. A process as defined in claim 12 wherein said
organometallic ester component is of the formula:
<IMG>
15. A process as defined in claim 12 wherein, in the
cross-linking silane, R2 and R3 are alkyl and, in the
organometallic ester component, R4 and R6 are hydrogen and
R5 is alkyl.
16. A process as defined in claim 13 wherein, in the
cross-linking silane, R2 and R3 are methyl, and in the
24

organometallic ester component, R5 is methyl, X is OC15H31,
and a is 1
17. A process as defined in claim 15 wherein, in the
organometallic ester component, R4 and R6 are each hydrogen.
18. A process as defined in claim 15 wherein, in the
cross-linking silane, R2 and R3 are methyl and, in the
organometallic ester component, R5 and X are methyl and
R4 and R6 are hydrogen.
19. A process as defined in claim 14 wherein the poly-
diorganosiloxane is
<IMG>
wherein n is from about 300 to about 5,260; the cross-
linging silane is (CH3 )Si(OCH3)3?
20. A process as defined in claim 13 wherein the
polydiorganosiloxane is
<IMG>
wherein n is from about 370 to about 1,350; the cross-
linking silane is CH3 Si(OCH3)3; and the organometallic
ester component is

<IMG>
21. A process as defined in claim 13 wherein, in the
organometallic ester component, a is 0 or 1 and R4 and
R6 are hydrogen or methyl.
26

Description

8SI-1551
1040~
This invention provides a novel process for manufacturing
a one-component, room-temperature vulcanizable silicone com_
po~ition which comprises passing a silanol chain stopped
polydiorganosiloxane, a cross-linking silane and a silanol
reactive organometallic ester compound of a metal through
_ 1- ,~

` 8SI-1551
~04~786
a devolatilizing extruder to form a one-component, room-
temperature vulcanizable silicone composition.
Background of the Invention - Single-component, room-
temperature vulcanizable compositions are known in the prior
art which vulcanize or cure to rubbery solids at room
temperature. Examples of these compositions are found in U.S.
3,689,454; U.S. 3,619,255; U.S. 3,647,725; U.S. 3,705,120; and
Canadian Serial No. 212,040 dated October 22, 1974.
The prior art method of preparing room temperature
vulcanizable compositions (RTV) has been by using a two-part
procedure of producing a base compound of diorganopolysiloxane
and a cross-linking agent. Thereafter, a separate catalyzation
step is carried out in another piece of equipment. In
particular, low modulus, one-package, room-temperature
vulcanizable elastomers have been prepared in this manner and
difficulty has been encountered in the production of these
compositions. The abbreviation of RTV as used herein means
a room-temperature vulcanizable material.
The chemical reactions, which form the curable low-
modulus RTV, result in the elaboration of substantial amounts
of heat which can result in a bubbled product due to the
vaporization of the byproduct methanol (b.p. = 64.7C). Also
high shear mixing is required during a high viscosity rise
which occurs during the preparation of the curable product.
These factors have resulted in a batch type manufacturing
process using different apparatus for different processing
steps.
It has now been found that a low modulus curable RTV
composition may be prepared by passing the organodipolysiloxane,
the cross-linking agent and the catalyst through a devolatilizing
extruder. This process allows for continuous production and
facilitates the incorporation of compounding ingredients at
-- 2 --

8SI-1551
104()786
precise points in the production stream so as to obtain the
desired degree of dispersion and chemical reaction. Surprising-
ly, it has been found that the use of viscosity minimizing
agents is substantially reduced or eliminated in this process
and, therefore, the product has an extended shelf life of 18
months as compared to the product of the prior art process
which has a shelf life of about 8 months. Accordingly, it is a
primary object of this invention to provide an improved process
for preparing a curable low modulus RTV composition.
It is also an object of this invention to provide a con-
tinuous process for the production of a curable catalyzed RTV
composition.
It is also an object of this invention to provide a
process for the production of a curable, catalyzed RTV composi-
tion which may be carried out without a viscosity minimizing
agent.
It is also an object of this invention to provide an
improved process for the production of a curable, catalyzed
RTV composition which rapidly de-aerates and devolatilizes
the composition as it is being blended.
Detailed Description of the Invention - The invention
provides a process for the preparation of a fluid composition
that is stable under substantially anhydrous conditions and
is curable to a self-bonding elastic solid in the presence of
moisture. The process com-prises passing 100 parts by weight
of a silanol chain stopped polydiorganosiloxane of the formula:
~ R ~
H0 ~ Si 0 ~ H
R
\ / n

-~ 8SI-1551
10~078~
wherein R and Rl are each, independently, organic radicals
of up to 8 carbon atoms selected from hydrocarbyl, halo-
hydrocarbyl and cyano lower alkyl and n is an average number
of from about 10 to 15,000, from 0.01 to 5.0 parts by weight
of a cross-linking silane of the formula:
R2m Si (OR )4-m
wherein R2 and R3 have the values defined for R and Rl herein-
above and m has a value of O to 3 and an average value based
on the total amount of silane in the composition of O to
1.99; and a silanol reactive organometallic ester compound of
a metal, said compound having radicals attached to the metal
atom, at least one of said radicals being a hydrocarbonoxy
radical or a substituted hydrocarbonoxy radical, said radicals
being at~ached to the metal atoms through M-O-C linkages
wherein M is the metal and any remaining valences of the metal
are satisfied by substituents selected from organic radicals
which are attached to the metal atom through M-O-C linkages,
-OH and -O- of a M-O-M linkage, the weight ratio of the silanol
reactive organometallic ester compound to the cross-linking
silane always being at least unity; and through a devolatilizing
extruder to form a fluid composition that is curable to a
self-bonding elastic solid in the presence of moisture.
Also, if desired, an extending and/or reinforcing filler
may also be passed to the devolatilizing extruder. Generally,
it may be preferred to feed separate streams of the compositions
to the devolatilizing extruder, but if desiredone or more
preblends of the components may be prepared and these preblends
may constitute a separate stream.
Generally, one or more silanol chain stopped polyorgano-
siloxanes of the above formula, having an average of at least
about 2.01 silicon-bonded alkoxy radicals per silicon atom and
the cross-linking silane compound and the silanol reactive
organometallic ester.
-- 4 --

--~ 8SI--1551
~()4~'~86
The components are preferably at room temperature during
mixing. Since the silanes tend to hydrolyze upon contact with
moisture, care should be exercised to exclude moisture when
the silane is fed to the devolatilizing extruder. Likewise,
care should be taken that the mixture of the silane, the silanol
reactive organometallic ester and the silanol chain stopped
polydiorganosiloxane is maintained under substantially anhydrous
conditions if it is desired to store the admixture for an
extended period of time prior to conversion of the composition
to the cured, solid, elastic silicone rubber state. On the
other hand, if it is desired to permit the mixture to cure
immediately, then no special precautions are necessary and the
three components can be extruded and placed in the form or shape
in which it is desired for the composition to be cured.
The amount of the silane cross-linker component to be
preblended with the silanol chain stopped polydiorganosiloxane
can vary within wide limits. However, for best results, it is
preferred to employ less than one mole of the silane per mole
of silanol groups in the silanol chain stopped polydiorgano-
siloxane component.
Moreover, it is preferred to employ an amount of organo-
metallic ester which provides a total number of moles of
silanol reactive ester linkages which is equal to or greater
than the total number of moles of terminal silanol groups in
the polydiorganosiloxane component.
~ithin the above framework, in the most preferred
compositions to be prepared by the process of this invention,
the weight ratio of silanol reactive to silane will be from
1 to 5Q, and especially preferably, from 1 to 10. Special
mention is made of weight ratios of from 1 to 5.
So long as the specified ratios of ingredients are
employed, a wide choice of components is available from which

8SI--1551
lV4~786
to prepare the compositions of this invention. These are
described in many places, such as Smith and Hamilton,
U.S. Patent No. 3,779,086 dated December 18, 1973, U.S. Patent
3,065,194 dated November 20, 1962; 3,294,739 dated ~ecember
27, 196~, 3,334,067 dated August 1, 1967 and 3,798,467 dated
January 2, 1973.
With respect to the silanol chain stopped polyorgano-
siloxane component (a), these can be selected from those
represented by the formula:
~ R
H0 ~ S 0 ~ H
wherein R and Rl are each organic radicals of up to 20, and
preferably, up to 8, carbon atoms selected from hydrocarbyl,
halohydrocarbyl and cyano lower alkyl, and n is a number that
varies generally from about 10 to 15,000, preferably from
300 to about 5,200, and more preferably, from 370 to 1,350.
The silanol chain-stopped polydiorganosiloxanes are well
known in the art and include compositions containing different
R and R groups. For example, the R groups can be methyl,
while the R groups can be phenyl and/or beta-cyanoethyl.
Furthermore, within the scope of the definition of polydiorgano-
siloxanes useful in this invention are copolymers of various
types of diorganosiloxane units, such as silanol chain-stopped
copolymers of dimethylsiloxane units, diphenylsiloxane units
and methylphenylsiloxane units, or for example, copolymers
of dimethylsiloxane units, methylphenylsiloxane units and
methylvinylsiloxane units. Preferably, at least 50% of the
R and Rl groups of the silanol chain-stopped polydiorgano-
siloxanes are alkyl, e.g., methyl groups.

~- 8SI-1551
104(~786
In the above formula, R and Rl can be, for example, mono-
nuclear aryl, such as phenyl, benzyl, tolyl, xylyl and
ethyl-phenyl; halogen-substituted mononuclear aryl, such as
2,6-dichlorophenyl, 4-bromophenyl, 2,5-difluorophenyl, 2,4,6-
trichlorophenyl and 2,5-dibromophenyl; alkyl such as methyl,
ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl,
tertbutyl, amyl, hexyl, heptyl, octyl; alkenyl such as vinyl,
allyl, n-butenyl-l, n-butenyl-2, n-pentenyl-2, n-hexenyl-2,
2,3-dimethylbutenyl-2, n-heptenyl; alkynyl such as propargyl,
2-butynyl; haloalkyl such as chloromethyl, iodomethyl, bromo-
methyl, fluoromethyl, chloroethyl, iodoethyl, bromoethyl,
fluoroethyl, trichloromethyl, di-iodoethyl, tribromomethyl,
trifluoromethyl, dichloroethyl, chloro-n-propyl, bromo-n-propyl,
iodoisopropyl, bromo-n-butyl, bromo-tert-butyl, 1,3,3-trichloro-
butyl, 1,3,3-tribromobutyl, chloropentyl, bromopentyl, 2,3-
dichloropentyl, 3,3-dibromopentyl, chlorohexyl, bromohexyl,
1,4-dichlorohexyl, 3,3-dibromohexyl, bromooctyl; haloalkenyl
such as chlorovinyl, bromovinyl, chloroallyl, bromoallyl, 3-
chloro-n-butenyl-l, 3-chloro-n-pentenyl-1, 3-fluoro-n-heptenyl-1,
1,3,3-trichloro-n-heptenyl-5, 1,3,5-tri-chloro-n-octenyl-6,
2,3,3-trichloromethylpentenyl-4; haloalkynyl such as chloro-
propargyl, bromopropargyl; cycloalkyl, cycloalkenyl, and alkyl
and halogen substituted cycloalkyl and cycloalkenyl such as
cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, 6-methyl-
cyclohexyl, 3,4-dichlorocyclohexyl, 2,6-dibromocycloheptyl,
l-cyclopentenyl, 3-methyl-1-cyclopentenyl, 3,4-dimethyl-1-
cyclopentenyl, 5-methyl-5-cyclopentenyl, 3,4-dichloro-5-cyclo-
pentenyl, 5-(tert-butyl)l-cyclopentenyl, l-cyclohexenyl, 3-
methyl-l-cyclohexenyl, 3,4-dimethyl-1-cyclohexenyl; and cyano
lower alkyl such as cyanomethyl, beta-cyanoethyl, gamma-cyano-
propyl, delta-cyanobutyl, and gamma-cyanoisobutyl.
A mixture of various silanol chain-stopped polydiorgano-
siloxanes also may be e~ployed. The silanol chain-stopped
-- 7 --

8SI-1551
1040786
materials useful in the RTV compositions of this invention have
been described as polydiorganosiloxanes but such materials can
also contain minor amounts, e.g., up to about 20% of mono-
organosiloxane units such as monoalkylsiloxane units, e.g.,
monomethylsiloxane units and monophenylsiloxane units. See,
for example, Beers, U.S. 3,382,205 dated May 7, 1968 and U.S.
Patent No. 3,438,930 dated April 15, 1969.
The silanol chain-stopped polydiorganosiloxanes employed
in the practice of the present invention may vary from low
viscosity thin fluids to viscous gums, depending upon the value
of n and the nature of the particular organic groups represented
by R and R .
The viscosity of the polydiorganosiloxane component can
vary broadly, e.g., in the range of 30 to lO,OOO,OOO cps. at
25C. Preferably, it will be in the range of 2,000 to l,OOO,OOO
and most preferably, from about 20,000 to 200,000 cps. at
25C.
The silane cross-linking agent of the formula:
R2 Si (OR )4-m
is one which has values for R2 and R3 which are the same as
those defined for R and Rl above.
Illustrative of such silanes useful in the RTV compositions
of this invention are the following:
CH3Si (OCH3)3
CH3Si (OCH2CH3)3
(CEI3)2Si (OCH3)2
( 3)3 3
~ Si (OCH3)3
Si ~OCH3)4
-- 8 --

8SI-1551
1040786
CH3cH2cH2cH2cH2cH2cH2cH2sI (OCH3)3
CF3CH2Si (CH3)3
NCCH2CH2Si (OCH3)3
(CH3)Si (OCH2CH2CH2CH3)3
The silanes are well known in the art and are disclosed,
for example, in Berridge, U.S. 2,843,555.
When the silane is employed as a cross-linking agent, m
has a value of 1 and the preferred silane is CH3Si(OCH3)3.
When it is desired to have a chain extending agent employed
in combination with the cross-linking agent, m has a value of
2 resulting in the silane being difunctional. The preferred
difunctional silane is (CH3)2Si(OcH3)2- The presence of a
chain extending agent results in a final cured product having
a higher degree of elasticity. The same result would be
obtained if a higher molecular weight silanol-stopped fluid
were used. Then, however,the curable composition also has
a higher viscosity and is very difficult to handle.
The modulus of elasticity can be improved still more by
using a silane of the above formula wherein m has a value of 3.
Thé preferred silane for this purpose is (CH3)3SiOCH3. The
use of such monofunctional silane chain terminating unit in
combination with the cross-linking and optional chain extending
silanes discussed above, not only results in a higher modulus
of elasticity but in many instances also provides a further
improvement in adhesion of the cured compositions to a
substrate.
The preferred silanes of the above formula will contain
on the average of from 1.05 to 3 silicon-bonded alkoxy groups
per silane when a fluid containing two silanol-containing
terminal groups is employed. If the number of alkoxy groups
are only two this merely results in a build-up of chain length.
Average in this situation means the total number of silicon-
_ g _

8SI-1551
104~786
bonded alkoxy groups divided by the total number of silane
molecules used in the RTV composition.
With respect to silanol reactive organometallic ester
component, in general the types of metals can vary broadly,
so long as silicon is not included -- because of the need to
provide a selectively hydrolyzable Si-O-M bond. Preferably,
the metal will be selected from lead, tin, zirconium, antimony,
iron, cadmium, barium, calcium, titanium, bismuth, manganese,
zinc, chromium, cobalt, nickel, aluminum, gallium or germanium.
Most preferably, the metal is titanium. The organometallic
compound is preferably an orthoester of a lower aliphatic
alcohol, a partially chelated ester of a lower aliphatic
alcohol with a ~-dicarbonyl compound or a partial hydrolyzate
of such compounds which retain at least one hydrocarbonoxy
radical or substituted hydrocarbonoxy radical attached to the
metal atom through M-O-C linkages.
Especially important are partially chelated organo-
metallic esters and particularly titanium compounds of the
formula:
~ - Ti -
or
\Ti
-- 10 --

8SI--1551
104~)786
wherein R4 is hydrogen, or an organic radical of up to 8 carbon
atoms selected from hydrocarbyl, halohydrocarbyl, or carboxy-
alkyl; R5 is a radical of up to 8 carbon atoms selected from
hydrocarbyl, halohydrocarbyl and cyano-lower alkyl; R6 is
selected from the same group as R and in addition from halo,
cyano, nitro, carboxy ester, or acyl and hydrocarbyl substituted
by halo, cyano, nitro, carboxy ester and acyl the total number
of carbon atoms in the R4 and in the R6 substituted alkanedioxy
radical being not more than about 18; R7 is selected from
hydrogen or an organic radical of up to 8 carbon atoms
selected from hydrocarbyl, halohydrocarbyl, or acyl and,
when taken together with RS forms together with the carbon
atoms to which they are attached a cyclic hydrocarbon
substituent of up to about 12 carbon atoms or such a
substituent substituted with one or more of a chloro, nitro,
acyl, cyano or carboxy ester substituents; X is a radical of
up to 20 carbon atoms selected from hydrocarbyl, halohydrocarbyl,
cyanoalkyl, alkoxy, haloalkoxy, cyanoalkoxy, amino or ether
and polyether groups of the formula ~(CqH2qO)VR where q is
from 2 to 4, v is from 1 to 20 and R is as defined above, a is
0 or an integer of up to 8 and, when a is 0, the ~ C R2
groups are bonded to each other in a cyclic fashion, and R8
is a radical of up to 8 carbon atoms selected from hydrocarbyl,
halohydrocarbyl or cyano-lower alkyl.
These are made by reacting a beta-dicarbonyl compound
with a titanium compound, to form a dialkoxy titanium chelate.
The dialkoxy titanium chelate can then be reacted with a
corresponding alkanediol to produce a wholly cyclic-substituted
chelated titanium compound. The preparation of such compounds
is described in the above U.S. Patent No. 3,779,986 dated
Dec./18/1973, and in U.S. Patent No. 3,334,067 dated August 1,
1967 and U.S. Patent No. 3,708,467 dated January 2, 1973.
-- 11 --

8SI-1551
1040786
illustrative of such compounds are:
2 CH~
OEt \
\
CH2 Ti~ ~ CH
CH3
~ Cg 19
2 ~ \
CH
OEt ~
~ 2
- 12 -

8SI -15 51
1040786
C~2 ~ - C
CH3
~ OEt
CH O ~ , O = C
2 ~ ~ /
CH 3 ~2
( 2 2 ) 9~\
2-- .\ ,~ O = C o
\ CH - / ~ C-C-CH
CH3 J2
~ NEt2
CH2 0 ~/ ~ O = C
CH2 ~ TiJ~ CH
CH O \ ~
3 / 2
ClCH
~2 / ~ 2 2
2 \ l-- = C
2 ~ ~C--CH3
CH2Cl /2
-- 13 -

8SI-1551
104~)786
CH2 Ti ~
--CH2 0 ~ 43 J
2 \ ~ ~ CH3
CH 2 ~ oC~ J
~ CH~\
2 \¦ = C
HO -- CH Ti CH
2 ~-- C
,~, Ti--~ ~C--CHf ~ ~
CH2CH 2

8SI-1551
104~786
o
CH3 - C - 0
CH~ ~ / 0CH2CH3 \
CH2-- O ~ C-CH2CH3
O C
CH3 / 2
O O - C
3)2 CH 2
¦ Tl ~ CH
(CH3)2- CH - / ~ C ~
~ CH3 ~ 2
Other examples will be readily apparent from the
description of substituents which may be present on the titanium.
Most preferably, component (c) will have the formula:
- 15 -

-~ 8SI-1551
104~786
/ 2 \ ~ " , CH3 (or OC
CH2 Ti CH
/' ~ ~
C~2 \ - C\
~ CH3 ~ 2
The RTV compositions of the present invention can also
be modified by the incorporation of various extenders or fillers.
Illustrative of the many fillers which can be em~loyed with
the compositions of the present invention are titanium dioxide,
lithopone, zinc oxide, zirconium silicate, silica aerogel,
iron oxide, diatomaceous earth, calcium carbonate, fumed silica,
silazane treated silica, precipitated silica, glass fibers,
magnesium oxide, chromic oxide, zirconium oxide, aluminum oxide,
crushed quartz, calcined clay, asbestos, carbon, graphite, cork,
cotton, synthetic fibers, etc. Among the most useful fillers
are calcium carbonate alone, or mixed with fumed silica.
Organosilicone- or silazane-treated silica fillers, such as
those described in Lucas, U.S. 2,938,009; Lichtenwalner, U.S.
3,004,859; and Smithr U.S. 3,635,743, are also particularly
suitable for use in the RTV compositions of the present invention.
The fillers are generally employed in amounts from about 5 to
about 200 parts, and preferably, from 10 to about 100 parts by
weight per 100 parts of silanol chain-stopped polydiorgano-
siloxane component.
In addition to fillers, the present compositions can also
optionally include an adhesion promoter, e.g., from 0.2 to 2
parts of such promoter per 100 parts of component. These will
generally be nitrogen-containing compounds, e.g., acetonitrile.
A preferred class of promoters is those of the formula:
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8SI-1551
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(R )3 bR b - Si - R - N \ N /
O \ /~ O
N
wherein G is the same as R10, hereinafter defined, a
(R110)3_bR b Si R9 radical, styryl, vinyl, allyl, chloro-
allyl or cyclohexenyl; R9 is a divalent radical selected
from alkylene-arylene, alkylene, cycloxylene and halosubstituted
such divalent radicals; R10 is a radical of up to 8 carbon
atoms selected from hydrocarbyl or halohydrocarbyl and Rll is
a radical of the type defined for R10 and also cyano lower
alkyl; and b is 0 to 3.
Such adhesion promoters are disclosed in the
Canadian Patent No. 943,544 dated November 12, 1974. The most
preferred such promoters are 1,3,5-tris-trimethoxysilylpropyl-
isocyanate and bis-1,3-trimethoxysilylpropylisocyanurate.
The preferred method of carrying out the process
of the invention is to feed separate streams of silanol chain
stopped polysiloxane, crosslinking silane, organometallic
ester and filler to a twin-screw devolatilizing extruder.
Optionally, if more than one filler is employed these may be
fed in separate streams to the extruder or they may be
preblended and fed as a separate stream. Pigments and other
adjuvants may also be added by the above-described procedure.
The preferred type of devolatilizing extruder is a
twin-screw Werner-Pfleiderer extruder mixer, Model Z SK.
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Description of the Preferred Embodiment - The following
embodiment is included to further illustrate the invention.
EXAMPLE 1
A preblend of 33.04 lbs. of a 90,000 cps silanol terminated
polydimethylsiloxane and 1.65 lbs. of a trimethylsilyl
terminated dimethyl D diphenyl D copolymer having a viscosity
of 20 to 30 cs. and a diphenyl D content of 14 mole percent is
prepared by mixing the components until a homogenous mixture
is prepared. A separate preblend of 4.21 lbs. methylsiloxane-
tetramer treated fumed silica having a surface area of approxi-
mately 200 m2g and 42.17 lbs of stearic acid treated calcium
carbonate is prepared by mixing the components until a
uniform mixture is obtained. As the polymer is fed to an
extruder, there are made sequential additions of the filler
blend and pigment. Also, 13.22 lbs of trimethylsilyl
terminated polydimethylsiloxane having a viscosity of 50 cs.
and a silanol content of 400-900 ppm is also fed to the
extruder with 3.82 lbs of a catalyst solution having the
formulation of 1.5 pts. by weight of methyltrimethoxysilane,
1.8 pts. by weight of 1,3-dioxypropanetitanium-bis-
ethylacetoacetate and 0.75 pts. by weight of 1,3,5-tris-
trimethoxysilylpropylisocyanurate.
The composition is extruded to form a fluid, curable
RTV which is filtered into an appropriate moisture proof
container.
EXAMPLE 2
Five separate streams of a 90,000 cps. silanol terminated
polydimethylsiloxane, a trimethylsilyl terminated dimethyl D
diphenyl D copolymer having a viscosity of 20 to 30 cs. and a
diphenyl content of 14 mole percent, a methylsiloxanetetramer
treated fumed silica having a surface area of approximately 200
m g, a stearic acid treated calcium carbonate and a catalyst
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as employed in Example 1, are fed to a Werner-Pfleider Model
Z SK-D 53 twin-screw devolatilizing extruder. The extrudate
is a fluid curable ~TV composition which is filtered into
moisture proof containers.
Obviously, other modifications and variaions of the
present invention are possible in the light of the above
teachings. It is, therefore, to be understood that changes
may be made in the particular embodiments of this invention
which are within the full intended scope of the invention
as defined by the appended claims.
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