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
2002-11-19
Dawson, Robert (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...
C528S012000, C528S029000, C528S031000, C528S032000, C528S033000, C528S025000, C528S018000, C525S478000, C525S474000, C556S051000
Reexamination Certificate
active
06482888
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a silicone composition and more particularly to a hydrosilylation addition-curable silicone composition comprising a specific combination of a hydroxy-functional organic compound and a titanium chelate. 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, a hydroxy-functional organic 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. The '921 patent also teaches the composition can optionally contain an unsaturated non-silicon-containing ether.
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.
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.
However, none of the aforementioned references teach the specific combination of a hydroxy-functional organic compound and titanium chelate of the present invention.
SUMMARY OF THE INVENTION
The present invention is directed a silicone composition prepared by mixing:
(A) 100 parts by weight of 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) 0.5 to 50 parts by weight of a hydroxy-functional organic compound having a molecular weight up to about 1000 and containing at least one hydroxy group and at least one aliphatic carbon-carbon multiple bond per molecule;
(D) 1 to 10 parts by weight of a titanium chelate having a formula selected from:
herein each R
1
is independently alkyl or —(R
7
O)
q
R
8
, wherein R
7
is hydrocarbylene, R
8
is hydrocarbyl, and q is from 1 to 20; each R
2
is independently hydrocarbyl, halohydrocarbyl, cyanoalkyl, alkoxy, cyanoalkoxy, 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 an integer from 1 to 3; and n is 1 or 2; wherein R
1
, R
2
, R
3
, R
4
, R
5
, and R
6
are free of aliphatic carbon-carbon multiple bonds; and
(E) 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 (E) in two or more parts, provided components (A), (B), and (E) 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.
The present invention is directed to a silicone composition prepared by mixing:
(A) 100 parts by weight of 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) 0.5 to 50 parts by weight of a hydroxy-functional organic compound having a molecular weight up to about 1000 and containing at least one hydroxy group and at least one aliphatic carbon-carbon multiple bond per molecule;
(D) 1 to 10 parts by weight of a titanium chelate having a formula selected from:
wherein each R
1
is independently alkyl or —(R
7
O)
q
R
8
, wherein R
7
is hydrocarbylene, R
8
is hydrocarbyl, and q is from 1 to 20; each R
2
is independently hydrocarbyl, halohydrocarbyl, cyanoalkyl, alkoxy, cyanoalkoxy, 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 an integer from 1 to 3; and n is 1 or 2; wherein R
1
, R
2
, R
3
, R
4
, R
5
, and R
6
are free of aliphatic carbon-carbon multiple bonds; and
(E) a catalytic amount of a hydrosilylation catalyst.
Component (A) is at least one organopolysiloxane containing an average of at least two silicon-bonded alkenyl groups per molecule. The organopolysiloxane can have a linear, branched, or resinous structure. The organopolysiloxane can be a homopolymer or a copolymer. The alkenyl groups typically have from 2 to about 10 carbon atoms and are exemplified by, but not limited to, vinyl, allyl, butenyl, and hexenyl. The alkenyl groups in the organopolysiloxane may be located at terminal, pendant, or both terminal and pendant positions. The remaining silicon-bonded organic groups in the organopolysiloxane are independently selected from monovalent hydrocarbon and monovalent halogenated hydrocarbon groups free of aliphatic unsaturation. These monovalent groups typically have from 1 to about 20 carbon atoms, preferably have from 1 to 10 carbon atoms, and are exemplified by, but not limited to alkyl such as methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl; cycloalkyl such as cylcohexyl; aryl such as phenyl, tolyl, xylyl, benzyl, and 2-phenylethyl; and halogenated hydrocarbon group such as 3,3,3-trifluoropropyl, 3-chloropropyl, dichlorophenyl, and 6,6,6,5,5,4,4,3,3-nonafluorohexyl. Preferably, at least 50 percent, and more preferably at least 80%, of the organic gro
Ahn Dongchan
Lutz Michael Andrew
Dawson Robert
Dow Corning Corporation
Milco Larry A.
Peng Kuo-Liang
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