COMPOSES DE SCELLEMENT AU SILICONE DURCISSABLES

CURABLE SILICONE CAULK COMPOSITIONS

Abrégé anglais

RD-19-814
CURABLE SILICONE CAULK COMPOSITIONS
Abstract of the Disclosure
Curable silicone caulk compositions are provided
using a nonionically stabilized silanol-terminated polydi-
organosiloxane, water, a silane cross-linker, a tin condensa-
tion catalyst, and calcium carbonate.

Revendications

RD-19.814
What is claimed is:
1. A silicone latex composition comprising by
weight,
(A) 100 parts of a base formulation consisting
essentially of an aqueous emulsion having 40
to 60% by weight solids and a pH in the range
of about 4 to 6, of a silanol-terminated poly-
diorganosiloxane and an effective amount of a
nonionic surfactant,
(B) 0.1 to 5 parts a of a silane cross-linker,
(C) 25 to 70 parts of calcium carbonate, and
(D) 0.3 to 2 parts of a stannoxane catalyst.
2. A caulk composition in accordance with claim 1,
where the polydiorganosiloxane is a silanol-terminated
polydimethylsiloxane.
3. A caulk composition in accordance with claim 1,
where the stannoxane is
<IMG> .
4. A caulk composition in accordance with claim 1,
where the silane cross-linker is methyltrimethoxysilane.
5. The invention as defined in any of the
preceding claims including any further features of
novelty disclosed.
-8-

Description

2~8~2 RD-ig 814
K C _ ~ QS T T~ 5
R~-e~.c~_t ~Rel~_~ ReQlica~i~n
This applica~ion is a continuation in part of
copending ap~lication Serial No. 200,482, filed May 3, 1988.
Bac~ou~1 of the ~vent~o~
Prior to the present invention, curable silicone
emulsions providing a~ elastomer upon water removal were
shown by J.F. Hyde et al., U.S. Patent 2,891,920. It was
found that the compositions of Hyde e~ al. required either a
strong acid or a strong base to achieve stability of the
emulsion. As a result, Hyde et al.'s silicone emulsions were
limited in use due to their adverse effects on various sub-
strates. Improved results are shown by D.E. Findlay et al.,
U.S. Patent 3,294,725, employing a surface acti~e sulfonic
acid catalyst to achieve a stable emulsion and allow for the
copolymerization of organosiloxanes and silacarbanes. An
additional procedure for making silicon rubber latexes is
shown by J. Cekada, vr., U.S. Patent 3,355,406, utllizing
silsesquioxanes to reinforce the polymer.
The present invention is based on the discovery
that stable aqueous curable silicone latex compositicns can
be made by initially emulsifying silanol-terminated poly-
diorganosiloxane in the presence of a nonionic surfactant,
such as an alkylaryloxypoly(ethyleneoxy)ethanol followed by a
pH adjus~ment up to 5 with a carboxylic acid, such as suc-
cinic acid. Also used in the emulsion are alkyltrialkoxysi-
2S lane, for example methyltrimethoxysilane and a tin catalyst,such as a stannoxane, hydroxystannoxane, or a monomethoxy tin
compound. Among the preferred tin compounds are stannoxanes
of the formula,

~ 8~ 19,814
(R)2SnX-O-Sn(Rl)2OH , (l)
where R and R1 are selected from the same or differen~ C(l-a)
alkyl radicals, and p-eferably butyl, and X is a halocen rad-
ical, or an acyloxy radical, and is preferably chloro.
S In aàdition, calcium carbona~e is utilized in the
resulting curable silicone composltion. The resulting sili-
cone caulk has been found to have superior shelf life, such
as six months or more, and elastomers resulting from the
removal of water from such caulking compounds have been found
to have excellent physical properties.
S~ ~n~ ^ f t~ ~ e ~ r - ^ n
There is p-o~ided by the presen~ invention, a sili-
cone caulking composit`on comprising by weight,
(A) lO0 parts of a base formulation consisting
essentially of an aqueous emulsion having 40
to 60% by weight solids and a pH in the range
of about 4 to 6, of a silanol-terminate~ poly-
diorganosiloxane having a molecular weight of
about sx103 to about 15x103, and an effective
amount of a nonionic surfàctant,
(B) O.l to 5 parts and preferably 0.5 to l.S part
of a silane cross-linker,
(C) 25 to 70 parts of calcium carbonate, and
(~) 0.3 to 2 parts and preferably 0.4 to l.5 part
of a stannoxane catalyst.
The aoueous emulsion of the silanol-terminated
polydiorganosiloxane are preferably made by agitating a lin-
ear silanol-terminated polydiorganosiloxane in an aqueous

RD-1~,814
;2r)18~)0~
medla ln the presence of 1~ to 5~ by weight of total e~ulsion
of a nonionic surfactant. The pH or the emulsion can be
adjusted to 4 to 6 by add ng a sarboxylic acid such as s~c-
cinic acid.
The silanol-terminated polydiorganosiloxanes wnich
can be used in the practice of the present invention have
organo radicals attached to silicon which are selected f~om
C~ 3), monovalent hydrocarbon radicals, and C~l_l3) monova-
lent hydrocarbon radicals substi~uted with radicals inert
during equilibration. Some of the organo radicals a_e, or
example, C(l-8) alkyl radicals such as methyl, ethyl, ?ro?yl,
butyl, pentyl, hexyl; haloalkyl radicals such as ~- 'uoro-
propyl; and cyanoal~yl radicals such as cyanoethyi and cyano-
propyl. In addition, the organo radicals attached to silicon
can be selected f-o~ alkenyl radicals such as vinyl -adicals;
allyl radicals; alkylaryl radicals such as ethyl, phenyl; ar.d
- arylalkyl radicals such as tolyl, xylyl, etc. The monovalent
organo radicals also can be aryl radicals such as phenyl,
halophenyl such as chlorophenyl, bromophenyl, naphthyl -adi-
2C cals, anthryl radicals, etc.
Silanol-~e-minated polydiorganosiloxanes useful in
the practice of the invention are shown by W. Noll, "Che~is-
try and Technology of Sillcones", Academic P_ess, ~ew York
(1968) p. 2~0. They can be prepared by the polymerization of
2~ cyclic siloxanes, such as octamethyltetracyclosiloxanes,
using acidic or basic catalysts. These silanolorganosilox-
anes can be e~ulsified in water with nonionic emulsifying
agents, such as alkylaryloxypoly(etheneoxy)ethanol. Useful
nonionic emulsifying agents are the nonionic surfactant which
can be used in the practice of the invention are, 'or exam-
ple, saponins, condensation products of fatty acids with
ethyleneoxide such as dodecylether of tetraethyleneoxide, anà

Z n ~ 2 ~3-13,814
condensation products of e~hyleneoxlde with sorbitan t-i-
oleate.
Acldic colloidal silica also can be used in the
practice of the invention in the silicone caulking comDosi-
tion which can be present at from 1 to 10 percent based ontotal weigAt of comoosition.
There is also u~ilized in the caulking composition
of the present invention, a trialkoxyorganosilane cross-
linker, such as methyltrimethoxysilane, to erfect a satisfac-
tory cure in the resulting elastomer. Additional tr~alkoxy-
organosiloxanes are, for example, methyltrie~hoxysilane,
e~hyltriethoxysilane, and methyltr propoxysllane.
The caulk composltions of the present inven~ion
have been found to have optimum shelf s~ability when there s
employed from about 0.3% to 0.6% by weight of stannoxane o.
formula (1). Stannoxanes of formula (1) and method fo- mak-
ing are shown by U.S. Patent 3,664,997. Preferably, he
stannoxanes of formula (1) include compounds such as
(C4H7)2SnCl-O-(C4H7)2SnOH, and
Q
(C4H7)2Sn(OCCH3)-O(C4H7)2SnOH .
Other tin compounds which can be used are, ~or
example,
o
(C4H7)25n(O~CH3)(OCH3).
In order that those skilled in the art will be be~-
ter able ~o practice the present nven~on, the following
example is given by way of illustration and not by way of
limitation. ~ll par~s are by weight.

2~8~ RD-19,814
Example
A base emulsion is prepared by passing through a
Gaulin homogenizer a mixture of a~out S000 grams of a
silanol-terminated polydimethylsilxoane, about S000 grams of
water and about 200 grams of polyethylene glycol ether. Thè
p~ of the resulting mlxture is adjusted by adding up to 200
grams of succinic acid. There is obtained a base formulation
having about 60~ solids and a pH of 4-5 of a silanol-termi-
nated polydimethylsiloxane having an MW of about 10,000.
A mixture of lS00 g of the above base formulation
is blended with 900 grams of ground calcium carbonate in a
Ross double planetary mixer for 30-60 m nutes, degassed,
passed through a high shear Semco mixer for 15 minutes, and
dispensed in~o anaerobic cartridges.
lS The above cartridges containing the base mixture
are then catalyzed by injecting them with methyltzimethoxysi-
lane, and in certain cases, acidic colloidal silica, along
with toluene, and a tin curing catalyst. The following cur-
able mixtures are prepared, which are shown in grams based on
100 parts of the base mixture, where "MTMS" is methyltrimeth-
oxysilane, "bu" is butyl, and "Laur" is
CH3(CH2)10C- :

RD-19 814
2~ 3C3~
~ 3 ~I 5
MTMS 0.5 0.5 0.5 0.5 0.5 0.5
toluene _ _ _ _ 1.0 1.0
colloidal silica _ 3.0 _ _ 3.0
5 bu2Sn~O~aur)2 0.33 _ _ _ _
bu2Sn(OMe))Laur) _ 0.5 0.5 _ _
[bu2Sn(OLaur)2O _ _ _ 0.5 _
bu2SnCl-O-Snbu7O~ _ _ _ _ _ 0.5 0.5
The materials are thoroughly mixed using a Semkit
mixer. the materials are then cured for one week prior to
tensile property measurement. Tensile properties are meas-
ured according to ASTM Standard D412 and the following
results are obtained, where Shore A is hardness, and TS is
tensile strength:
15 _ 1 _ 2 3 4 5 6
5~o~e A 19 (251~ 2s(28)~ 17 (12~ -22 ~2~ '14 ~15) 15~12)~
TS (p~i) 93(76)178(166)130(108)148(118)162(181)159(187)
Strain (~) 398(219) 551t527) 638(625)513(501)595 (6B21 6s6t694)
* Numbers in parentheses refer to pro~erties obtained from
materials aged in the tube for two weeks and a one week
cure period.
** Numbers in parentheses refer to properties obtained from
materials aged in the tube for one month and one week
cure period.
5 **~ Numbers in parentheses refer to pro?erties obtained from
materials aged in the tube for two months and one week
cure period.

RD-i9 814
8~)0;2
The above results show t:hat the stannoxanes are
valuable condensation catalysts and materials formulated with
these catalysts maintain their elonga~lon upon aging.
Although the above resu:Lts are directed to only a
few of the very many variables which can be used in the prac-
tice of the present invention, it should be understood that
the present invention is directed to a much broader variety
of caulk compositions utilizing stannoxanes, sllanol-termi-
nated polydiorganosiloxanes, cross-linking silanes, as shown
in the description preceding these examples.