Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-06-06
2003-01-28
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C528S015000, C524S413000
Reexamination Certificate
active
06512037
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a silicone composition and more particularly to a hydrosilylation addition-curable silicone composition containing a titanium or zirconium compound having at least one aliphatic carbon-carbon multiple bond. The present invention further relates to a cured silicone product formed from the composition.
BACKGROUND OF THE INVENTION
Silicones are useful in a variety of applications by virtue of their unique combination of properties, including high thermal stability, good moisture resistance, excellent flexibility, high ionic purity, low alpha particle emissions, and good adhesion to various substrates. For example, silicones are widely used in the automotive, electronic, construction, appliance, and aerospace industries.
Addition-curable silicone compositions comprising an alkenyl-containing organopolysiloxane, an organohydrogensiloxane, a titanium compound or zirconium compound, and a hydrosilylation catalyst are known in the art. For example, U.S. Pat. No. 5,364,921 to Gray et al. discloses a composition curable to a silicone rubber, which comprises an alkenyl-containing polydiorganosiloxane, an organohydrogensiloxane, a hydrosilylation catalyst containing platinum, an epoxy-functional organotrialkoxysilane, an alkoxysilicon compound, and a titanium compound having Ti—O—CH bonds.
U.S. Pat. No. 5,683,527 to Angell et al. discloses a foamable, curable organosiloxane composition comprising an alkenyl-functional polyorganosiloxane, an organohydrogensiloxane, a blowing agent, a platinum catalyst, and an adhesion promoter comprising an epoxy-functional compound, a hydroxyl-functional compound, a tetralkylorthosilicate, an organotitanate, and an aluminum or zirconium compound.
U.S. Pat. No. 5,595,826 to Gray et al. discloses organopolysiloxane compositions which cure by the addition reaction of silicon-bonded lower alkenyl radicals with silicon-bonded hydrogen atoms. The compositions comprise an adhesion promoting mixture comprising an epoxy-functional compound, a compound having at least one hydroxy group and, in the same molecule, at least one substituent selected from a group consisting of silicon hydride, alkenyl, and acryl, and an aluminum compound or zirconium compound.
U.S. Pat. No. 4,742,103 to Morita et al. discloses organopolysiloxane compositions curable by a platinum catalyzed hydrosilylation reaction comprising an organosilicon compound containing an ethylenically unsaturated group at least one alkoxy group, and at least one member from a specified class of compounds of aluminum or zirconium.
European Patent Application EP 0 718 432 A1 to Collins discloses a curable coating composition comprising a composition curable by a hydrosilylation reaction and includes a silicone resin, a hydrosilylation reaction inhibitor, and an adhesion promoting additive which comprises an organosilicon compound having epoxy and alkoxy functionalities, an alkenylsilanol, an organotitanium compound, and a metal chelate compound.
European Patent Application EP 0 596 534 A2 to Kasuya et al. discloses a curable organopolysiloxane composition comprising a polyorganosiloxane having at least two alkenyl groups, an organopolysiloxane having at least two silicon-bonded hydrogen atoms, an organosilicon compound having 1 to 20 mole % organosilsesquioxane units, 20 to 80 mole % diorganosiloxane units, and 20 to 80 mole % triorganosiloxy units in which there is at least one epoxy group per molecule, at least 2 mole % of the organic groups are alkenyl, and at least 5 mole % of the organic groups are silicon-bonded alkoxy groups, an organotitanium compound, and a hydrosilylation-reaction catalyst.
Although, the aforementioned references disclose silicone compositions containing various titanium and zirconium compounds, none of the references teach the transition metal compound of the present invention.
SUMMARY OF THE INVENTION
The present invention is directed to a silicone composition comprising:
(A) an organopolysiloxane containing an average of at least two silicon-bonded alkenyl groups per molecule;
(B) an organohydrogenpolysiloxane containing an average of at least two silicon-bonded hydrogen atoms per molecule in a concentration sufficient to cure the composition;
(C) an effective amount of a transition metal compound having a formula selected from:
wherein each R
1
is independently hydrocarbyl, —(R
7
O)
q
R
8
, —SiR
9
2
(OSiR
9
2
)
r
OSiR
9
3
, epoxy-substituted hydrocarbyl, acryloyloxy-substituted hydrocarbyl, methacryloyloxy-substituted hydrocarbyl, amino-substituted hydrocarbyl, or hydrocarbylamino-substituted hydrocarbyl, wherein R
7
is hydrocarbylene, R
8
is hydrocarbyl, R
9
is hydrocarbyl, q is from 1 to 20, and r is from 0 to 20; each R
2
is independently hydrocarbyl, halohydrocarbyl, cyanoalkyl, alkoxy, alkenyloxy, alkenyloxyalkyloxy, cyanoalkoxy, methacryloyloxyalkyloxy, acryloyloxyalkyloxy, amino, or hydrocarbyl-substituted amino; each R
3
is independently hydrogen, hydrocarbyl, halohydrocarbyl, or acyl; each R
4
is independently hydrocarbyl, halohydrocarbyl, or cyanoalkyl; R
5
is alkanediyl, wherein the free valencies are separated by 3, 4, or 5 carbon atoms; R
6
is hydrocarbylene, wherein the free valencies are separated by 2, 3, or 4 carbon atoms; M is titanium or zirconium; m is an integer from 0 to 3 when M is titanium or an integer from 0 to 4 when M is zirconium; n is an integer from 1 to 3 when M is titanium or an integer from 1 to 4 when M is zirconium; and p is 1 or 2; provided at least one R
1
, R
2
, R
3
, R
4
, R
5
, or R
6
per molecule contains at least one aliphatic carbon-carbon multiple bond; and
(D) a catalytic amount of a hydrosilylation catalyst.
The present invention is further directed to a cured silicone product comprising a reaction product of the above-described composition.
The present invention is still further directed to a multi-part silicone composition comprising components (A) through (D) in two or more parts, provided components (A), (B), and (D) are not present in the same part.
The silicone composition of the present invention has numerous advantages, including low VOC (volatile organic compound) content and adjustable cure. Moreover, the silicone composition cures to form a silicone product having superior adhesion to a wide variety of substrates, particularly plastics.
The silicone composition of the instant invention has numerous uses, particularly in the electronics field. For example, the silicone composition can be used to attach a die to a printed circuit board, encapsulate an electronic device, fill the gap between a heat sink and an electronic device, attach a heat sink to an electronic device, or encapsulate the wire windings in a power transformer or converter. In particular, the silicone composition is useful for bonding electronic components to flexible or rigid substrates.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the term “aliphatic carbon-carbon multiple bond” refers to an aliphatic carbon-carbon double bond or carbon-carbon triple bond.
A silicone composition according to the present invention comprises:
(A) an organopolysiloxane containing an average of at least two silicon-bonded alkenyl groups per molecule;
(B) an organohydrogenpolysiloxane containing an average of at least two silicon-bonded hydrogen atoms per molecule in a concentration sufficient to cure the composition;
(C) an effective amount of a transition metal compound having a formula selected from:
wherein each R
1
is independently hydrocarbyl, —(R
7
O)
q
R
8
—SiR
9
2
(OSiR
9
2
)
r
OSiR
9
3
, epoxy-substituted hydrocarbyl, acryloyloxy-substituted hydrocarbyl, methacryloyloxy-substituted hydrocarbyl, amino-substituted hydrocarbyl, or hydrocarbylamino-substituted hydrocarbyl, wherein R
7
is hydrocarbylene, R
8
is hydrocarbyl, R
9
is hydrocarbyl, q is from 1 to 20, and r is from 0 to 20; each R
2
is independently hydrocarbyl, halohydrocarbyl, cyanoalkyl, alkoxy, alkenyloxy, alkenyloxyalkyloxy, cyanoalkoxy, methacryloyloxyalkyloxy, acryloyloxyalkyloxy, amino, or hydrocarbyl-substituted amino; eac
Ahn Dongchan
Lutz Michael Andrew
Dow Corning Corporation
Milco Larry A.
Moore Margaret G.
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