COMPOSE AU SILICONE PROMOTEUR DE DURCISSEMENT

ADDITION CURING SILICONE COMPOSITIONS

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
An addition curing silicone composition with
a low viscosity in the uncured state and high physical
strength in the cured state comprising a vinyl-containing
diorganopolysiloxane polymer, platinum catalyst, a
hydride cross-linking agent and a linear hydride coupler
in which the viscosity of the linear hydride coupler
varies from 1 to 1,000 centipoise at 25°C.

Revendications

- 21 - 60SI-273
The embodiments of the invention in which an
exclusive property or privilege is claimed are defined
as follows:
1. An addition curing silicone composition with
a low viscosity in the uncured state and a high physical
strength in the cured state comprising (A) 100 parts by
weight of a vinyl-containing diorganopolysiloxane having
a viscosity varying from 100 to 200,000 centipoise at
25°C., where the diorganovinylsiloxy content varies from
0.14 to 2.0 mole percent and the organo group is a
monovalent hydrocarbon radical; (B) from 0.1 to 500 parts
per million of a platinum catalyst; (C) from 0.1 to 25
parts by weight of a crosslinker selected from the class
consisting of hydride resins having only terminal
hydrogen atoms and linear hydride polysiloxanes wherein
said linear hydride polysiloxane has hydrogen atoms only
in the internal position of the siloxane chain, and
(D) from 75 to 150 parts by weight of a linear hydride
polysiloxane coupler having hydrogen atoms bonded only at
the terminal silicone atoms in the siloxane chain wherein
said coupler has a dimethyl hydrogen siloxy content of from
3.0 to 9.0 mole percent and the viscosity of the linear
hydride coupler varies from 1 to 500 centipoise at 25°C.
2. The composition of claim 1 wherein the
coupler has the formula,
<IMG>
where R1 is a monovalent hydrocarbon radical other than
olefinic hydrocarbon radicals and n varies such that the
viscosity of the polymer varies from 1 to 500 centipoise
at 25°C.
3. The composition of claim 2 wherein there is

- 22 - 60SI-273
present from 5 to 100 parts by weight of a filler.
4. The composition of claim 3 wherein the
filler is selected from the class consisting of fumed
silica, precipitated silica and mixtures thereof.
5. The composition of claim 4 wherein the
vinyl-containing diorganosiloxane has the formula,
<IMG>
where Vi is vinyl and R2, R3 are monovalent hydrocarbon
radicals other than olefinic hydrocarbon radicals and
t varies such that the diorganopolysiloxane's viscosity
varies from 100 to 200,000 centipoise at 25°C.
6. The composition of claim 5 wherein the
crosslinker is selected from the class consisting of a
hydride resin having
<IMG>
units, and SiO2 units where the R4 + H to Si ratio
varies from 1.0 to 2.7 and hydride resin of the formula,
<IMG>
units SiO2 and R6R6SiO units where the R5 + R6 + H to
Si ratio varies from 1.2 to 2.7 where R4, R5 and R6 are
monovalent hydrocarbon radicals other than olefinic
hydrocarbon radicals.
7. The composition of claim 5 wherein the
crosslinker is a linear hydride polysiloxane having
the formula
<IMG>

- 23 - 60SI-273
where R7 is a monovalent hydrocarbon radical other than
an olefinic hydrocarbon radical and p and q vary such that
the hydride polysiloxane has a viscosity that varies from
1 to 1,000 centipoise at 25°C. and wherein the polysiloxane
has from 0.4 to 1.6% by weight of hydrogen.
8. The composition of claim 7 wherein there
is further present from 10 to 100 parts by weight of an
organopolysiloxane copolymer comprising <IMG> units and
SiO2 units where R8 is a radical selected from the class
consisting of vinyl radicals, alkyl radicals, aryl radicals
and fluoroalkyl radicals where the weight ratio of mono-
functional units to tetrafunctional units is from 0.5:1 to
1:1 and wherein from about 2.5 to 10 mole percent of the
silicon atoms contain siloxane bonded vinyl groups.
9. The composition of claim 7 wherein there is
further present from 10 to 100 parts by weight of an organo-
polysiloxane copolymer comprising <IMG> units, <IMG>
units and SiO2 units where R8 is a radical selected from
the class consisting of vinyl radicals, aryl radicals,
alkyl radicals and fluoroalkyl radicals where the ratio
of monofunctional units to difunctional units is from
0.5:1 to 1:1 and the difunctional units are present in
an amount equal to from about 1 to 10 mole percent based
on the total number of siloxane units in the copolymer
and where from about 2.5 to 10 mole percent of the silicone
atoms contain silicon bonded vinyl groups.
10. The composition of claim 7 wherein there
is further present from 5 to 40 parts by weight of
diorganopolysiloxane of the formula,
<IMG>
where R10 is a monovalent hydrocarbon radical other than
an olefinic hydrocarbon radical, Vi is vinyl, and R11 is

- 24 - 60SI-273
a monovalent hydrocarbon radical and w varies such that
the viscosity of the diorganopolysiloxane varies from 50
to 50,000 centipoise at 25°C.
11. The composition of claim 7 wherein there
is further present in the composition from 100 to 100,000
parts per million of an inhibitor compound selected from
the class consisting of vinyl-containing organocyclo-
tetrasiloxane, trialkyl, cyanurate, alkyl maleate and
mixtures thereof.
12. The composition of claim 7 wherein there
is present at least 0.001 parts by weight of an inhibitor
compound having at least one hydroperoxy radical of the
formula,
- C - O - O - H.
13. A process for forming an addition cure
silicone composition with a low viscosity in an uncured
state comprising (1) mixing (A) 100 parts by weight of a
vinyl-containing diorganopolysiloxane having a viscosity
varying from 100 to 200,000 centipoise at 25°C., where
the diorganovinylsiloxy content varies from 0.14 to 2.0
mole percent and the organo group is a monovalent hydro-
carbon radical; (B) from 0.1 to 500 parts per million of
a platinum catalyst; (C) from 0.1 to 25 parts by weight
of a crosslinker selected from the class consisting of
hydride resins having only terminal hydrogen atoms and
linear hydride polysiloxanes wherein said linear hydride
polysiloxane has hydrogen atoms only bonded at the
internal position of the siloxane chain, and (D) from 4
to 15 parts by weight of a linear hydride polysiloxane
coupler having hydrogen atoms bonded only at the terminal
silicone atoms in the siloxane chain wherein said coupler
has a dimethyl hydrogen siloxy content of from 3.0 to
9.0 mole percent and the viscosity of the linear hydride
coupler varies from 1 to 500 centipoise at 25°C., and
(2) allowing the composition to cure to a silicone
elastomer.

- 25 - 60SI-273
14. The process of claim 13 wherein the coupler
has the formula,
<IMG>
where R1 is a monovalent hydrocarbon radical other than
olefinic hydrocarbon radicals and a varies such that the
viscosity of the polymer varies from 1 to 1000 centipoise
at 25°C.
15. The process of claim 13 wherein there is
further present 5 to 100 parts by weight of a filler.
16. The process of claim 15 wherein the filler
is selected from the class consisting of fumed silica,
precipitated silica and mixtures thereof.
17. The process of claim 16 wherein the vinyl
containing diorganopolysiloxane polymer has the formula,
<IMG>
where Vi is vinyl and R2 and R3 are monovalent hydro-
carbon radicals other than olefinic radicals and t varies
such that the diorganopolysiloxane polymer viscosity
varies from 100 to 200,000 centipoise at 25°C.
18. The process of claim 17 wherein the cross-
linking agent is selected from the class consisting of a
hydride resin having
<IMG>
units and SiO2 units where the R4 + H to Si ratio varies

- 26 - 60SI-273
from 1.0 to 2.7 and hydride resin of the formula,
<IMG>
units, SiO2 and R6R6SiO units where the R5 + R6 + H to Si
ratio varies from 1.2 to 2.7 where R4, R5 and R6 are
monovalent hydrocarbon radicals other than olefinic
hydrocarbon radicals.
19. The process of claim 17 wherein the cross-
linker is a linear hydride polysiloxane having the
formula,
<IMG>
where R7 is a monovalent hydrocarbon radical other than an
olefinic hydrocarbon radical and p and q vary such that
the hydride polysiloxane has a viscosity that varies from
1 to 1,000 centipoise at 25°C. and wherein the polysiloxane
has from 0.4 to 1.6% by weight of hydrogen.
20. The process of claim 19 where there is
further present from 10 to 100 parts by weight of an
organopolysiloxane copolymer comprising <IMG> units
and SiO2 units where R8 is a radical selected from the
class consisting of vinyl radicals, alkyl radicals,
aryl radicals, and fluoroalkyl radicals where the weight
ratio of monofunctional or tetrafunctional is from 0.5
and wherein from about 2.5 to 10 mole percent of the
silicone atoms contain silicon bonded vinyl groups.
21. The process of claim 19 wherein there is
further present from 10 to 100 parts by weight of an
organopolysiloxane copolymer comprising <IMG> units,
<IMG> units and SiO2 units where R8 is a radical selected

- 27 - 60SI-273
from the class consisting of vinyl radicals, aryl radicals,
alkyl radicals and fluoroalkyl radicals where the weight
ratio of monofunctional units to difunctional units is
from 0.5:1 to 1:1 and the difunctional units are present
in an amount equal to from 1 to 10 mole percent making
the total number of siloxane units in the copolymer and
where from about 2.5 to 10 mole percent of the silicone
atoms contain silicon bonded vinyl groups.
22. The process of claim 19 where there is
further present from 5 to 40 parts by weight of a dior-
ganopolysiloxane of the formula,
<IMG>
where R10 is a monovalent hydrocarbon radical other
than an olefinic hydrocarbon radical, Vi is vinyl, and
R11 is a monovalent hydrocarbon radical and w varies such
that the viscosity of the diorganopolysiloxane varies
from 50 to 50,000 centipoise at 25°C.
23. The process of claim 19 where there is
further present in the composition from 100 to 10,000 parts
per million of an inhibitor compound selected from the
class consisting of vinyl containing organocyclotetra-
siloxanes, trialkyl cyanurates, alkyl maleates and
mixtures thereof.
24. The process of claim 19 wherein there is
further present at least 0.001 parts by weight of an
inhibitor compound having at least one hydroperoxy
radical of the formula,
- C - O - O - H .

Description

~L~L7~i7~
- 1 - 60 SI 273
ADDITION CURING SII.ICONE COMPOSITIONS
... .
Background of the Invention
The present invention relates to addition curing
system and more particularly the present invention relates
to addition curing systems which have a low viscosity in
the uncured state and high physical strength in the curea
state.
The addition curing SiH olefin systems are
well known. Basically such systems comprise a vinyl
containing diorganopolysiloxane base polymer, a platinum
catalyst and a hydride cross-linking agent which can be
either a linear hydride or a hydride containing resin
composed of monofunctional units and tetrafunctional
units or a hydride resin composed of monofunctional units,
tetrafunctional units and difunctional siloxy units. An
early patent on such type of compositions is that of
Modic United States Patent 3,436,366, issued April 1, 196g
which discloses the use of a silicone resin composed of
monofunctional siloxy units, difunctional siloxy and
tetrafunctional siloxy units. This resin has a
certain vinyl content and is utilized as an additive to
the basic SiH olefin platinum catalyst composition.
It has been found that this composition may be useful as
both a molding and encapsulating composition. The use
of vinyl containing resins permits the lowering of the
amount of silica filler there is incorporated in the
composition. As a result the composition has a good
physical strength with a low viscosity in the uncured
.,,,

1~7~7~
60 SI 273
state making the composition an excellant composition as
far as potting and encapsulate uses.
A further modification of such systems can be
found in Jeram et al U.S. Patent 3,957,713 issued
May 18, 1976. This patent discloses that a high strength
silicone composition be obtained by incorporate in the
basic vinyl SiH olefin platinum catalyzed systems a low
viscosity polysiloxane fluid which is terminated at one
end of the polymer chain with triorganosiloxy groups and
the other end polymer chain with a vinyl diorganosiloxy
groups. It was also dislosed in such systems there could
be utilized from 5 to 70 parts of a filler, which is
preferably a fumed silica or precipitated silica treated
filler. The silica could be either treated with cyclic
polysiloxane or silazanes or preferably both. It is
necessary to have all these ingredients in the co~position
to arrive at a hi~h strength in the cured state that
is a tear strength in the 100 to 200 psi range.
Recently, there have been developments in the
field of molding compositions, specifically there has
been developed liquid injection molding apparatus
forming plastic parts. This apparatus is expensive,
however, through its use, molded parts can be for~ed at
a reduced cost. There have been attempts to develop
silicone compositions for such an application. The
dif~iculty with composition of United States Patent
Number 3,957,713 was that the composition did not have
a sufficiently low viscosity in the uncured state. For
liquid injection molding machines, it is desired that the
uncured viscosity be as low as possible, but generally
in the range of 10,000 to 500,000 centipoise at 25~C.
If the composition has this viscosity, it can be
readily forced into the molding chamber of the liquid
injection molding machine and then the composition has to
has to have another property, that is, it has to cure
at a sufficiently rapid rate. Upon being heated to
:,

~L~767~
60 SI 273
-- 3 --
elevated temperatures, the molded parts can be formed with
rapidity. The faster the parts are formed by the liquid
injection molding machine, the lower the cost of the part
that is formed and the more is the saving in labor that
is realized compared to the production of such molded
parts by a different method.
For such liquid molding application, it was
desirable to develop a silicone composition which could
be utilized readily. It was highly desirable to have a
silicone compostion such as that of Modic which would
have a sufficient tear strength in the range of 100 to
200 psi in the cured state and the composition would have
a viscosity in the uncured state varying from 10,000 to
500,000 centipoise at 25C and more preferably varying
from 10,000 to 200,000 centipoise at 25C. In addition,
it is desired that the composition be able to be cured
at elevated temperature; that is temperatures above
100C in a period of 1 to 10 seconds.
It should be noted as disclosed in Bobear U.S.
Patent 4,061,60g which issued December 6, 1977 that
hydroperoxy inhibitors have been developed which can be
incorporated to SiH platinum additions systems such
that they can be packaged in a single package such that
it will not cure at room temperature but would cure
rapidly at elevated temperatures about 100C.
One successful attempt to produce liquid
injection molding compositions was theproduction of
silicone polymers that are fluorosubstituted such that
the cured part has good solvent resistnace as disclosed
in Jeram U.S. Patent 4,041,010 issued August 9, 1977.
The patent discloses f~uorosilicone compositions
comprising as the base fluorosilicone polymer a vinyl
fluorosilicone resin combined with a hydride cross-
linking agent and a platinum catalyst. The composition
35 disclosed that optionally there may be utilized a filler
in the composition; however, in order to get the higher

71!~
60 SI 273
-- 4 --
tensile s-trengths of the composition, it is necessary to incorporate
a filler. Accordingly, this composition is not altogether as
advantageous as would be desired.
Another disclosure of a fluorosilicone composition which
can be utilized in liquid injection molding machines is to be found
in Jeram U.S. Pat. 4,029,629 issued June 14, 1977. This composition
discloses the use of a reinforcing filler in co~bination with the
basic fluorosilicone composition. Accordingly, for such application
the composition of U.S. Pat. 4,041,010 is much to be preferred over
that of U.S. Pat. 4,029,629.
Accordingly, it was highly desirable to find some technology
whereby there could be obtained a silicone addition cured composition
which would have a low viscosity in the uncured state, that is, in
the range of 100,000 to 500,000 centipoise at 25C and would have a
cured tear strength in the range of 100 to 200 psi in the cured
state and such that it would have a fast cure rate of 1 to 10 seconds
at elevated temperatures, that is, temperatures about 100C. It is
preferred in such a composition in order to keep the viscosity low in
the uncured state that the composition contain as low an amount of
reinforcing filler as can possibly be used consistent with a high
strength in the cured state.
Accordingly, it is one object of the present invention
to provide an SiH olefin addition cured system having a high strength
in the cured state and a low viscosity in the uncured state.
It is another object of the present invention to provide
for an SiH olefin platinum catalyst addition cured system which has a
fast cure rate at elevated temperature.
It is still another object of the present invention to
provide for an SiH olefin platinum catalyæed addition cured system
which is guitable for liquid injection molding applications.
It is still an additional object of the present invention
to provide for a process for producing an SiH olefin platinum
catalyzed addition cured system which has high strength in the cured
state and a low viscosity in the uncured state. These and other
objects of the present invention are accomplished by means of the
disclosure set forth herein below.

:~L1'7~7~1
60 SI 273
-- 5 --
Summary of the Invention
In accordance with the above objects there is provided
by the present invention, an addition curing silicone composition
with a low viscosity in the uncured state and high strength in the
cured state comprising ~A) 100 parts by weight of a base vinyl
containing diorganopolysiloxane polymer having a viscosity
varying from 100 to 200,000 centipoise at 25~C where the
dimethyvinylsiloxy content varies from 0.14 to 2.0 mole percent and
the organo group is a monovalent hydrocarbon radical; ~B) from
0.1 to 500 parts per million of a platinum catalyst; ~C~ from
0.1 to 25 parts by weight of a cross-linking agent selected from
the class consisting of hydride resins and linear hydride poly-
siloxane other than thermal containing hydrogen atoms only in
other than terminal positions on the silicone chain; and (D)
from ~ to 15 parts by weight a coupler which is a linear hydride
polysiloxane with hydrogen atoms on only the terminal silicone
atoms in thesiloxane chain where the dimethyl hydrogen siloxy
content varies from 3.0 to 9.0 mole percent and the viscosity
of the linear hydride ranges from 1 to 1000 centipoise at 25C.
Preferably the linear hydride coupler has the formula,
R - Rl ~- R
(1) H- SiO:-. - ...... io_ _ si H
R ll R
1 n`
where R, R are monovalent hydrocarbon radicals other than olefinic
hydrocarbon radicals and n va-ies such that the viscosity of the
polymer varies from 1 to 1000 centipoise at 25C.
The coupler is utilized in the composition so as to
increase the molecular chaing length of the vinyl containing
vinyl terminated diorganopolysiloxane base polymer to high
molecular weight without increasing the viscosity of
' - :

60 SI 273
67~
-6-
the composition in the uncured state. However, the high molecular weight
diorganopolysiloxane vinyl containing base polymer that results from reaction
with the coupler in the initial base polymer results in a composition with
good physical strength in the cured state and a rapid cure rate at elevated
temperatures.
Description of the Preferred Embodiment
The bas~icconstituents of ~heinstant composition comprises 100 parts by weight
of a base vinyl containing diorganopolysiloxy polymer having a viscosity
varying from 100 to 200,000 centipoise at 25C where a (CH3)2 ViSiOo 5 con-
tent generally varies from 0.05 and 3.5 and more preferably varies from
0.14 to 2.0 mole percent. The organic groups are monovalent hydrocarbon
radicals preferably the organo groups are selected from alkyl radicals such
as methyl ethyl propyl etc..; alkenyl radicals such as vinyl, ally~ etcO;
cycloalkyl radical such as cyclohexyl, cycloheptyl, and etcO; mononuclear
aryl radicals such a5 phenyl, ethylphenyl etc.; and haloalkyl such as 3,3,3-
trifluoropropyl. ~ost preferably the monovalent hydrocarbon radical is
selected from an alkyl radical of 1 to 8 carbon aton~s or phenyl. Pre~erably
there is no vinyl or alkenyl radicals in the central part o~ the polysiloxane
chain o the base vinyl containing polymer. This is especially important in
the instant case since the vinyl groups in the internal position of the polymer
chain will tend to cross-link with a coupler rather than be chain extended.
Accordingly, preferably, the base vinyl containing polymex does not have any
vinyl groups or olefinical ~nsaturated groups in the internal position of the
pQlymer chain but just has vinyl in the termlnal position of the polymer chain.
An example of a str~lctural formula for the vinyl containing diorganapolysiloxane
base polymer is as follows:
R2 ~ R2 ¦ ~2
(2) Vi - - Si0 -- Si0 - - Si - Vi
R R l2
t
where Vi is vinyl and R and R are monovalent hydrocarbon radicals other
than olefinic hydrocar~on radicals and t varies such that the diorgano-
polysiloxane polymer viscosity ~aries from 100 to 200,000 centipoise at 25~C.
. . _ . _ _ _ _ . . _ . . _ _ . _ . . _ . . , _ . . _ _ _ . . _ . . .

~7~ 60 SI 273
-7-
2 3
Preferably R and R are selected from alkyl radicals of 1 to 8 carbon atoms
such as methyl ethyl propyl; mononuclear aryl radicals such as phenyl, methyl-
phenyl, ethylphenyl; cycloalkyl radicals, cycloheptyl and haloalkyl radicals
such as 3,3,3-trifluoropropyl. Most preferably the R and R radicals are
selected from alkyl radicals of 1 to 8 carbon atoms and phenyl~
The polymers of Formula ~2) are generally prepared by equilibrating the
apppropriate cyclo tetrasiloxane with the appropriate vinyl terminated low
molecular weight polysiloxane chainstoppers. The chain-stopper is preferred
for such equilibration reaction and is preferably a low molecular weight
vinyl terminated polysiloxane compounds such as a disiloxane, trisiloxane,
tetrasiloxane and so forth. These low molecular weight vinyl terminated
polysiloxane polymers are produced by hydrolyzing the appropriate chloro-
silanes particularly vinyl diorganochlorosilanes along with diorganodi-
chlorosilanes to produce the desired chainstopper. ~his chainstopper is then
taken in a relatively pure form and equilibrated along the cyclotetrasiloxanes
with the appropriate substitute groups in the presense of a catalyst to pro-
duce the desired vinyl terminated diorganopolysiloxane polymer having a
viscosity varying from 100 to 200,000 centipoise at 25C. The catalyst that
is utilized is preferably a rnild acid catalyst, such as toluene, sul-
fonic acid or an acid treated clay such as filtrol, which a sulEuric acid
activated clay manufactured and sold by Filtrol Corporation of Los Angeles,
California. When the equilibration has proceeded to the point where about
85% of the cyclopolysiloxanes have been converted to the linear polymer, the
acid catalyst is neutralized with a base or simply filtered out in the case
of the acid activiated clay to leave behind the linear polymer. Preferably
excess cyclics are stripped off so that the linear polymer will have a low
volatile content and be relatively pure~ There can also be utilized an alkali
metal hydroxide as the catalyst such as for instance potassium or soaium
hydroxide.
The second necessary ingredient in the compositon of the instant case is from
0.1 to 25 parts by weight per 100 parts the base vinyl containing polymer of
a cross-linking agent selected from the class consisting of hydride resins
and a hydride polysiloxane having hydrogen atoms solely in the internal portion
of the polysiloxane chain. Accordingly, there may be utilized a hydride resins
selected from these hydride resins including units of the formulae:

~ 7~7~ 60 SI 273
--8--
a) H SiOo 5
l4
units and SiO2 units where the R + ~ to Si ratio varies from 1.0 to 2.77
,
b) H 1 0.5
R5
units, SiO2 units and R~R Sio units where the R + R + H to Si varies
Erom 1.2 to 2.7 wherein R , R and R are monovalent hydrocarbon radical3
other than olefinic hydrocarbon ~adicals.
Most preierably R , R , R are selec~ed fxom alkyl radicals of 1 to 8 carbon
atoms; mononuclear aryl radicals such as phenyl, ethyl pheny~ etc.; cyclo-
alkyl radicals such as cycloheptyl, cyclooctyl; etc.; haloalkyl radicals such
as 3,3,3-trifluoropropyl, etc. most preferably R , R , R as selected from
alkyl radicals of l to 8 carbon atoms and phenyl radicals. It is important
that there be no aliphatic unsaturated groups for the R4, R5, R6 radicals.
These hydrides can be simply produced in the controlled hydrolysis of the
corresponding hydride chlorosilanes in the presence of a hydrocarhon organic
solvent. For the resin containing only monofunctional units and tetrafu~ctional
` uni~sr a hydrogen diorganochlorosilane is hydrolyzed along with a tetrachloro-silane to produce the desired resin. In the case of the resin containing the
monofunctional siloxy units, the difunctional siloxy units, and the tetra-
functional silo~y units, there is hydrolyzed a hydrogen diorgaono dichloro-
silane, a tetrachlorosilane and a diorganodichlorosilane in the desired ratios
to produce the desired resins. ~ost information as to the process by which
said resins are produced, one is re~erred to the patent of E. M. Jeram,
u~.S.p.- 4,041,010 which issued August 9, 1977.
In place of the hydride resins as cross-linking agents which are undesirable
to some extent since they may cross-link the composition too much for the
hydride coupler to work, there may be used a linear hydrogen containing poly-
.... . . , .. .. _ _ __ __ _ . . . .

- ~1767~4 60 SI 273
_g_
siloxane as the cross-linking agentO Accordingly, as the cross-linking agent,
there may be utilized a linear hydride polysiloxane having the formula,
R7 ~~~~ ~~ ~ R7
R7 SiO - - - SiO - - ~ SiO ~ Si ~ R
17 ~ 17 ~ 1 17 ~ 17
where R is a monovalent hydrocarbon radical other than an olefinic hydro-
carbon radical and p and q vary such that the polymer has a viscosity that
varies from 1 to 1,000 centipoise at 25C and wherein the polysiloxane has
from 0.04 to 1.4 by weight of hydrogen. The hydride polymer of Formula (3)
is noticeable in that there is no hydrogen groups in the terminal silicone
atoms. The only hydrogen groups in Formula (3) above is in the internal
position of the polymer chain. Accordingly, even though such a polymer
cross-}inks, the base vinyl containing polymer to produce a cross-linked
composition, it cannot function as a coupler. Accordingly, it does not
compete with the coupler function of the hydride coupler of the instant case.
Such a hydride polymer of Formula ~3) above is produced by equilibrating
the appropriate hydrogen cyclopolysiloxane with the appropriate cyclo poly-
si}oxane containing R substituent groups, in the presence of disiloxane,
trisiloxane, and other low molecular weight linear triorganosiloxy end-stopped
chain-stoppers. The process is much the same as producing the vinyl con-
taining polymer; however, such hydride cross-linking agents may be made by an
alternate process. This alternate process comprises hydrolyzing the appro-
priate chlorosilanes in water along or in the presence of a hydrocarbon solvent
to produce a mixture of cyclics and linear hydride polymers of Formula (3)
above. The cyclics can be stripped off.
Along with the cross-linking agent of the base vinyl containing polymer there
must be present in the composition, a platinum catalyst. The platinum cata-
lyst may be soiid platinum, deposited on a carrier such as charcoal or gamma-
alumina. It is preferable that the platinum catalyst is a solubilized platinum
catalyst complex. It should also be noted that the catalyst may be utilized in
the concentration of anywhere from 0.1 to 500 parts per million of the total
.... ... . .. .. . . .

~'7~14
60 SI 273
-- 10 --
composition and more preferably, from O.1 to lO0 parts per million
of the total composition.
Many types of platinum compounds for this SiH olefin
addition reaction are known and such platinum catalysts may be used
also for the reaction oE the present case. The prefexred platinum
catalysts especially when optieal clarity is re~uired are those
platinum~compound catalysts which are soluble in the present
reaction mixture. T~e platinum compound can be selected from those
having the formula ~PtCl201efin)2 and H(PtC1301efin) as described in
U.S. Pat. 3,159,601 - Ashby - issued December 1, 1964. The olefin
shown in the previous two formulas can be almost any type of olefin
but is preferably an alkenylene having from 2 to 8 carbon ato~s, a
cycloalkenylene having from 5 to 7 carbon atoms or styrene. Specific
olefins utilizable in the above formulas are ethylene, propylene, the
various isomers of butylene, octylene, cyclopentane, cyclohexane,
cycloheptane.
A further polatlnum containing material uscible in the
composition of the present invention is the platinum chloride
eyclopropane complex ~PtC12C3H6)2 described in U.S. Patent 3,159,662
Ashby issued December l, 1964.
Still, further, the patent containing material can be a
complex formed from chloroplatinic acid with up to 2 moles per gram
of a member selected from the class consisting of alcohols, ethers,
aldehydes and mixtures of the above as described in U.S. Pat.
3,220,972 - lamoreaux - issued November 30, 1965.
The preferred platinum compound to be used not only as a
flame retardant additive is that disclosed in Freneh Patent No.
1,548,775, Karstedt. Generally speaking, this type of platinum
complex is formed by reaction ehloroplatinie aeid containing 4 moles
of water of hydration with tetravinylcyelotetrasiloxane in the
presenee of sodium bicarbonate in an ethanol solution.
The above form is the basic components of the Si~ olefin
platinum eatalyst eomposition that is a base vinyl containing polymer,
a hydride cross-linking agent and a platinum eatalyst. The
resulting composition will cure to a silicone elastomer at room
temperature gradually or at elevated temperatures in a very rapid

60 SI 273
-- 11 --
manner. The way this composition differs from the prior art
composition is in the presence of a hydride coupler, which is a
linear hydride polysiloxane with hydrogen atoms only a terminal
silicone atom in a siloxane chain where the dimethyl hydrogen siloxy
content varies from 3.0 to 9.0 mole percent and the viscosity of the
linear hydride comprises a coupler varying from :L to 500 centipoise at
25C. In formula (1), R and R are other than olefinic hydrocarbon
radicals. Accordingly, preferably, R can be selected from the
group consisting of alkyl radicals of 1 to 8 carbon atoms such as
methyl ethyl propyl etc.i cycloalkyl radicals such as cyclohexyl,
cycloheptyl, and etc., mononuclear aryl radicals such as phenyl,
methyl, ethyl phenyl, etc.; and haloalkyl radicals such as 3,3,3-
trifluoropropyl. Most preferably, the R and R radiGals are
selected from alkyl radicals of 1 to 8 carbon atoms and phenyl
radicals. The hydride coupler is prepared by either a hydrolysis
process or by acid catalyzed equilibration process. In the
equilibration process the appropriate cyclotetrasiloxanes are
equilibrated a low molecular weight a hydrogen terminated chain-
stoppers, such as a dihydrogen tetraorgano disiloxane. q'he acid
catalyzed equilibration reaction is much the same as that disclosed
for the production of the vinyl containing base polymer. By the
hydrolysis process the appropriate hydrogen diorganochlorosilanes
are hydrolyzed with the appropriate amount of diorganodichlorosilanes
to produce the desired polymer of Formula (1) above. When the
hydride coupler is produced, it can be separated from the undesirable
amount of cyclics by strippin~ the cyclics from water and other
impurities and utilized as a coupler in the addition curing
compositions of the instant case.
The amount of coupler utilized is at a weight ratio
30 generally from .75 to 1.5 and preferably 0.8 to 1.2 of the silicon
bonded vinyl groups present in the hydride coupler. Accordinly, if
there i9 present from a weight ratio varying from .75 to 1.5 and more
preferably to 0.9 to 1.2 of silicon bonded vinyl groups in the base
vinyl containing polymer to silicon bonded hydride groups in the
hydride coupler there will be obtained the proper chain extending
acitivity that is desired by the hydride coupler. If there is less

~17~ 4
60 SI 273
- 12 -
than this amount of hydride in terms of the hydride coupler in the
composition the chai.ns will not be extended enough and if there is
more than the desired amount of hydride as indica-ted by the above
ratio in the composition, then there will be too much hydride
present and the compositions will be slow in curing to a silicone
elastomer.
The hydride coupler and hydride cross-linker preferably
mixed with the base vinyl containing composition to form a single
package, some vinyl polymer preferably mixed with the platinum
catalyst to form another package. ~hen it is desired to cure the
composition, the two packages are simply mixed together and allowed
to cure either gradually at room temperature of rapidly at elevated
temperatures, that is, temperatures above 100C. The platinum
catalyst is desirably incorporated along with some vinyl polymer in
a separate package. The hydride coupler is mixed with the vinyl
containing polymer, along with the platinum. Accordingly, it is
desirable that the composition or ingredients are kept apart in
two packages such as set forth above. However, it is possible to
provide a one-pac~age composition when an appropriate amou~t of
inhibitor is catalyzed which results in a composition that has a
shelf life 03-. 6 months or more in a single package. This is possible
with a certain inhibitor as will be explained later. By the
utilization of the coupler and specifically the hydride couplers as
disclosed above, it is possible to obrain a composition in which
the chain length of the base vinyl containing polymer is increased to
a high molecular weight without unduly increasing the viscosity of the
uncured composition. By the utilization of a hydride coupler, it is
possible to obtain an addition curing composition with a tensile strength
oE about 800 psi, an elongation of about 400 percent, a tear strength of
200 psi and a Shore Durometer A of about ~0.
To obtain the high physical strength of the composition,
there may be incorporated from 5 to 100 parts by weight of a filler
based on a 100 parts of the base vinyl containing polymer. A filler
can be selected from fumed silica, precipitated silican and mixtures
thereof. Preferably the amount of fumed or precipitated silica that
it utilized in the composition is less than 50 parts by weight based

Lt767~34
60 SI 273
- 13 -
on 100 parts by weight of ~le base vinyl containing polymer since
fumed silica and precipitated silica although they desirably increase
the physical strength of the composition, nevertheless, have an
undesirable effect in that they increase the viscosity of the uncured
composition undesirably. In place of the reinforcing filler such as
fumed silica and precipitated silicas, they may be utili~ed extending
fillers which do not unduly increase the viscosity of the composition
in the uncured state, but increasing to some extent the tensile
strength of the composition. The reinforcing and extending fillers
are, for instance, titanium dioxide, lithopone, zinc oxide, zirconium
silicate, silica aerogel, iron oxide, diatomaceous earth, calcium
carbonate, silizane treated silicas, glass fibers, magnesium oxide,
chomic oxide, zirconium oxide, aluminum oxide, alpha quartz, calcined
clay, carbon, graphite, cork, cotton, synt~etic fibers and so forth.
Many of these fillers and, particulary, fumed silica and
precipitated silica, even though they have been treated with silazanes
or cyalopolysiloxanes, unduly increase the viscosity of the
composition in the uncured state which is undesirable for liquid
injection molding applications. Accordingly, for liquid injection
molding applications, it is desirable that the total composition has
a viscosity that does not exceed 500,000 centipoise at 25C and more
preferably, does not exceed 200,000 centipoise at 25C. The lower
the viscosity of the uncured total composition can be maintained
while the cured composition has good tensile strength and good
elonation, the more desirable the composition is for liquid
injection molding application. Accordingly, for this reason, it
is preferred that there not be used too large a quantity of
reinforcing filler and extending fillers in the composition.
A method of increasing the tensile strength of the
composition without unduly increasing the uncured viscosity is to
incorporate a vinyl containing resin in the composition. Accordingly,
per 100 parts by weight of the base vinyl containing polymers,
there may be present from 10 to 100 parts by weight of an organo
polysiloxane copolymer comprising R3Sioo 5 units and SiO2 where R
is a radical selected from the class containing of vinyl radicals,
alkyl radicals and aryl radicals, and fluoroalkyl radicals of 1 to 8
'
.

~1~67~L
60 SI 273
carbon atoms with a ratio of monofunctional units and
tetrafunctional units, is from 5:1 to 1:1 and where
from about 2.5 to 10 mole percent of the silicone atoms
contains silicon bonded vinyl groups.
A slightly different resin that can also be
used in the composition to increase the tensile strength
of the cured composition without unduly increasing the
viscosity of the uncured total composition is that there
may be incorporated per 100 parts of the base vinyl
polymer from 10 to 100 parts by weight of an organo
polysiloxane copolymer comprising R3SiOo 5)R2 Si units
and SiO2 where R is a radical selected from the class
consisting of vinyl radicals, aryl radicals, alkyl
radicals and fluoroalkyl radicals with a ratio of
~onofunctional units to difunctional units is from 0.5:1
to 1:1 and the difunctional units are present in an amunt
equal from about 1 to 10 mole percent based on the total
number of siloxane units in the copolymer and where from
about 2.5 to 10 mole percent o~ the silicone atoms
contains silicone bonded vinyl groups. For information
as to the utilization of such resins in addition curing
compositions one is referred to the issued Patent of
F. J. Modic, U.S. Pat. 3,436~366. In the above units of
of the resin, R8 has been disclosed as being selected
from vinyl radicals, aryl radicals, and alkyl radicals
and ~luoroalkyl radicals, more preferably, R8 is
selected from vinyl radicals, alkyl radicals of 1 to 8
carbon atoms, phenyl radicals and 3,3,3-trifluoropropyl
radicals.
In place of the ~inyl containing resins that
may be utilized, a polysiloxane polymer having a vinyl
group at one terminal position of a siloxane chain and
having a triorgano siloxy group on the other terminal
position of the polysiloxane chain. Accordingly,
per 100 parts of the base Yinyl containing polymer,

~1~67~34
60SI 273
- 15 -
there may be utilized from 5 to 40 parts by weight a
diorganopolysiloxane of the formula,
R10 Rll R10
R10 lio_~lio ~!i~vi
110 L 1 11 i W l 10
where R10 is a monovalent hydrocarbon radical other
than an olefinic hydrocarbon radical/ Vi is vinyl,
and Rll is monovalent hydrocarbon radical and w
varies such that viscosity of the diorganopolysiloxane
varies from 50 to 50,000 centipoise at 25C.
In Formula (4) R is again preferably
an alkyl radical of 1 to 8 carbon atoms, a
phenyl radical or a 3,3,3-trifluoropropyl radical.
For more information as to such polymer~ and their use in
such SiH olefin platinum catalyst compositions, refer
to the patent of Jeram et al, U.S. Patent 3~957,713. As
lS pointed out previously, such polymer which have a
terminal-vinyl group on one end of the siloxy chain
and triorganosiloxy group on the other terminal
portion of the polymer chain, it is advantageous
in increasing the tensile strength of the cured
composition without unduly increasing the viscosity
of the uncured total composition.
In addition to the foregoing compounds
present in the composition, there may be present 100
to 100,000 parts per million of an inhibitor
compound selected from the class consisting of
vinyl containing organocycle tetrasiloxanes such as a

~L~76~
60 SI 273
- 16 -
methyl vinyl cyclotetrasiloxane, trialkylcyanurate,
an alkyl maleate and mixtures thereof. The example
of alkyl maleate as an inhibitor as an addition curing
silicone composition is, for instance, to be found
in the U.S. Pat. 4,256,870 of Echberg, issued
March 17, 1981. With the exception of the alkyl maleates,
the other inhibitors are relatively mild inhibitors which
are utilized to give the composition when it has been
mixed into a single mixture, a certain amount of shelf
life at room temperatures so that the composition will
cure at elevated temperatures, that is, temperatures about
100C in a matter of minutes and even seconds. However,
if it is desired to the total composition in a single
package composition, there may be utilized an even
stronger inhibitor, that is, there may be utilized at
least .001 parts by weight per 100 parts of the base
polymer of an inhibitor compound having at least one
hydroperoxy radical of the formula - C - O - O - H as
disclosed in Bobear, U.S. Pat. 4,061,60~. The hydroperoxy
inhibitors allow all the ingredients to be mixed into a
single package and yet the composition will not cure
at room temperature for periods along as six months to
l year or even more, but when heat at elevated temperatures,
that is temperatures above 100C, will cure in a rapid
manner.
In accordance with the present disclosure, it is
possible to have an addition curing silicone composition
with novel properties that has good Tensile Strength,
Elongation, Tear and Duorometer hardness without an unduly
high viscosity in the uncured states. This makes the
composition desirable for liquid injection molding
applications.
The examples below are given for the purpose
of illustrating the present invention and are not
for the purpose of setting limits and boundaries in

~ ~67~4 60 SI 273
- 17 -
in the disclosure of the instant case. All parts in the examples are by
weight.
Example 1
There was prepared a composition A comprising 30 parts by weight of a vinyl
chain-stopped polymer of 80,000 centipoise viscosity, 31.8 parts at 4000
centipoise at 25C vinyl chain-stopped polymer 10.0 par~s of silazane treated
fumed silica, 15.0 parts of silazane treated precipitated silica. Both of
these fumed silica were treated with hexamethyldisilazane. To this there
was added 1.5 parts of titanium oxide, 10 parts per milllon of platinum as
disclosed in Lamoraux patent as disclosed in U.S.P. 3,220,972,15.0 parts
of dimethylvinyl chain-stopped at one end and trimethylsiloxy at the other
end of 500 centipoise viscosity fluid to form a Composition A.
~here was formed a Composition B comprising 2 parts by weight of a resin
compound of dimethyl hydrogen monofunctional siloxy units and te~rafunctional
siloxy units where the resin contained 0.2 weight percent hydrogen. Eight
parts of 4000 centipoise at 25C vinyl chain stopped dimethylpolysiloxane
polymer and 5 parts by weight of a dimethyl hydrogen terminated dimethyl
polysiloxane having 20 dimethyl silox~ units in the polymer chain. The mixed
viscosity of Composition ~ was 150,000 centipoise. ~he mixed viscosity of
composition A was 200,000 centipoise at 25C. There was cured 100 parts of a
composition A with 15 parts of Composition B are 100C for one hour and the
composition had the following physicals:
Shore A 25
Tensile 625 psi
Elongation 500%
~ear Stength 170 pi
Exam~le 2
There was prepared 100 parts of a composition C as 61~8 parts of 4000 centi-
poise at 25C vinyl chain stopped dimethypolysiloxane polymer. There was
added to this 10 parts of silazane treated fumed silica and 15 parts by
weight of silazane treated precipitated silica. To this there was 5 parts
by weight of vinyl dimethyl terminated trimethyl siloxy terminated poly-
methylsiloxy polymer of 500 centipoise at 25C. To this mixture there was
.. . . _ .

~L~L7~;7~34
- 18 -
added 8 parts by weight of a hydrogen dimethyl terminated dimethyl poly-
siloxane hydride coupler oE Example 1 to which was added 2.0 parts oE the
hydride resin of Example 1 and 500 parts per mlllion of the inhibitor
methyl vinyl cyclo tetrasiloxane the viscosity of mixed composition was
40,000 centipoise at 25C. There was prepared a Composition D comprising
100 parts by weight of dime~hyl vinyl chain-stopped at one end and tri-
methyl siloxy chain-stopped at the other end poly~er of 500 centipoise at
25C with 100 parts per million of Lamorea~x catalyst. The resulting
mixture had a viscosity of 40,000 centipoise at 25C, 100 parts of the
CompOsitiQn C which was cured with 10 parts of Compositioa D for 1 hour
to produce a composition with the following physicals:
Shore A 21
Tensile 640 psi
Elongation 540%
Tear Streng~ 158 pi
Example 3
There was then prepared a composition E comprising 61.8 par~s of 4000
centipoise at 25C vinyl chain-stoppped polysiloxane polymer, 15.0 parts
of silazane treated fumed silica, 15.0 parts of silazane treated precipitated
silica, 5.0 parts of a vinyl dimethyl chain-stoppped at one end and a tri-
methyl siloxy chain-stopped at the other end
25C, a.o parts of the hydride coupler of Example 1, 2.0 parts of the hydride
resin of Example 1 and 2000 parts per million of the methyl vinyl cyclo-
tetrasiloxane inhibitor of Example 2. The viscosity of the mixed composition
was 85,000 centipoise at 25C. The resulting composition of composition E
was cured by mixing 10 parts of Composition E wi~h 1 part of each of four
different catalyst compositions, compositions F, G, H, and }. Composition
F comprises 100 parts by weight of the dimethyl vinyl, trimethyl silyl end-
stopped polydimethylpolysiloxane of 500 centipoise at 25C and 100 parts
per million of part is Lamoreaux catalyst. The viscosity of the resultant
mixed composition was 85,000 centipoise at 25C. Composition G comprises
100 parts by weight a dimethyl vinyl chain-stopped on both ends dimethyl
siloxane polymer of 400 CentlpOise Vlscosity at 25C and 100 parts per
,

~L~7~7~4l
- 19 -
million as platinum of Lamoreaux catalyst. Composition H comprise 50 parts
by weight of a dimethyl vinyl chain-stopped on both ends, polydimethyl
siloxane at 400 centipoise viscosity at 25C and 50 parts by weight 1 to 1
by weight of dimethyl vinyl trimethyl siloxy end-stopped polysiloxane at
500 centipoise viscosity. To this there was added 100 parts per million
as platinum Lamoreaux catalyst. There was then prepared Composition I
comprising 100 parts by weight of a dimethyl vinyl chain-stopped polydimethyl-
polysiloxane of 4000 centipoise viscosity to which was addecl 100 parts per
million as platinum of Lamoreaux catalyst. The mixed viscosity of
Composition G was 85,000 centipoise and then mixed viscosity of composition
was 85,000 centipoise at 25C. The resulting compositions when utilizing
lo parts of weight of Compositions F, G, H, and I per 100 parts of Composition
~ were cured at 100C for 1 hour to yield cured elastomers having the following
properties as shown in Table I below.
TABLE I
1/100C 1/100C 1/100C 1/100C
~ _cals Phys _als Physicals ~y~icals
Shore ~ 23 3~ 27 28
Tensile Strength770735 720 750
psi
Elongation,% 570 430 500 580
Tear Strength,pil42175 200 170
Example 4
_
There was prepared a Composition J comprising 61.8 parts of a dimethyl
vinyl chain-stopped polydimethyl siloxy polymer of 4,000 centipoise viscosity
15.0 parts of a silazane treated- f~ed ~liça-~5~.0~par-ts o~ia ~ilazane
treated precipitated silica filler, 5.0 parts of 1:1 dimethyl vinyl trimethyl-
siloxy end-stopped polydimethyl siloxane of 500 centipoise at 25~. To
9~ 8parts of the Composition J was added in each case the following parts
hydride coupler of Example 1 and the hydride resin of Example 1 and also the
concentration of Lamoreaux catalyst as shown in Table 2 below. The resulting
compositions were cured for one hour at 100C and then the physicals were
taken. The physicals of these compositions are shown in Table 2.

; ` 60 SI 273
` ` ~1767~
- 20 -
TABLE II
Component 4 5 6 7 8 9
Composition J 96.8 pts. 96.8 96.8 96.8 96.8 96.8 96.8
Hydride Coupler
of Example 1 8.0 --- 2.0 4.0 6.0 8.0 12.0
Hydride Resin
of Example 1 2.0 2.0 2.0 2.0 2.0 2.0 1.5
Methyl Vinyl
Tetramer2,000 ppm 2,0002,0002,0002,000 2,0002,000
ppm ppm ppm ppm ppm ppm
~amoreaux
Platinu~ Catalyst10 ppm pt10ppm10ppmlOppm10ppm10ppm 10ppm
P~ Pt Pt Pt Pt Pt
l/100C Physicals
Shore A 34 46 45 43 37 34 24
Tensile 735 750 715 745 680 735 500
Elongation430 300 340 38Q 410 430 450
Tear Strength 175 60 60 64 200 175 166
... . . . . _ . .
`: :
: ~,