Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2000-09-13
2002-09-17
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S006000, C522S063000, C522S068000, C522S099000, C522S069000, C522S148000, C522S172000, C522S040000, C522S041000, C522S044000, C522S046000, C522S047000, C522S048000, C522S052000, C522S053000, C427S508000, C427S515000, C427S517000, C427S519000, C428S446000, C428S447000, C428S452000
Reexamination Certificate
active
06451869
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to photo-active cyclopentadienylplatinum (IV) compounds, and to irradiation-curable silicone compositions containing such compounds as photo-active platinum (IV) catalysts.
Drahnak, U.S. Pat. No. 4,600,484, is directed to a hydrosilylation process involving the addition between silicon hydride compounds (i.e. compounds containing the Si—H moiety) and compounds containing aliphatic unsaturation. Drahnak discloses that his process is activated by actinic radiation. Drahnak uses a platinum complex having the formula,
CpPt(R)
3
, (1)
where Cp is cyclopentadienyl and R is a C
1-18
aliphatic organic radical.
The Drahnak catalyst consists of a cyclopentadienyl group, Cp, eta-bonded to a platinum (IV) group, Pt(CH
3
)
3
, which is substituted with three sigma bond ed aliphatic radicals. It is al so reported in U.S. Pat. No. 4,600,484, that the cyclopentadienyl group Cp can be further modified with organosilyl groups.
Boardman et al., U.S. Pat. No. 4,916,169, shows a visible light-activated hydrosilylation process for effecting the addition of a silicon hydride to compounds containing aliphatic unsaturation. In accordance with the hydrosilylation practice of Boardman et al., a polycyclic aromatic organic compound, such as anthracene, is physically blended as a sensitizer with a photo-active platinum compound, such as shown by formula (1). Based on the theory of Boardman et al., the sensitizer effects a visible light energy transfer to further enhance the photo-activation of the platinum compound. While beneficial cure results are reported by Boardman et al., it has been found that the sensitizer is sometimes incompatible in the silicone curable silicone mixture and/or a large amount of sensitizer is required to be effective.
It would be desirable therefore to provide additional procedures for improving the efficiency of photo-activated platinum (IV) compounds as catalysts for effecting the cure of irradiation-curable silicone compositions.
Further, it would be desirable to provide photo-active platinum compounds comprising a cyclopentadienyl group chemically combined to a Pt (IV) group, which did not require the separate blending of an incompatible organic material, such as anthracene, into an irradiation-curable silicone mixture.
BRIEF SUMMARY OF THE INVENTION
The present invention is based on the discovery that a cyclopentadienylplatinum (IV) compound of formula (2), having a C
7-20
aromatic organic radical attached to the cyclopentadienyl is more effective as a hydrosilylation catalyst for effecting the cure of an irradiation-curable silicone mixture, than is a mixture an aromatic organic compound, for example, phenanthrene and a photo-active cyclopentadienylplatinum (IV) compound, such as shown by formula (1), which is free of aromatic substitution.
In one of its embodiments the present invention comprises platinum (IV) compounds having the formula,
[(R
1
)
a
(R
2
)
b
Cp]Pt(R
3
)
3
(2)
where R
1
is a C
7-20
aromatic organic radical, R
2
and R
3
are each independently a C
1-22
aliphatic organic radical, Cp is a cyclopentadienyl radical, “a” is an integer equal to 1 to 3 inclusive, “b” is an integer equal to 0 to 3 inclusive, and the sum of a+b is equal to 1 to 4 inclusive.
In another of its embodiments the present invention comprises a method for making platinum (IV) compounds of formula (2), comprising, effecting reaction between a C
7-20
aromatic substituted cyclopentadienyl species having the formula,
(R
1
)
a
(R
2
)
b
CpM, (3)
and a platinum (IV) compound having the formula,
XPt(R
3
)
3
(4)
where R
1
, R
2
, R
3
, Cp, “a” and “b” are as previously defined, M is a metallic anion, such as lithium, and X is an anionic leaving group, such as triflate, borate, phosphate, or halogen.
In still another of its embodiments the present invention comprises irradiation-curable silicone compositions comprising,
(a) an alkenyl-substituted polydiorganosiloxane having alkenyl radicals attached to silicon by carbon-silicon bonds, where the alkenyl radicals can be in the terminal position, in the polymer backbone, or a combination thereof,
(b) a silicon hydride cross-linker, and,
(c) an amount of a photo-active cyclopentadienyl-platinum (IV) compound of formula (2) which is sufficient to convert the irradiation-curable silicone composition to a tack-free state when said composition is subjected to 240-400 nm light.
In still another of its embodiments the present invention comprises a method of coating a substrate with a cured tack-free silicone film, which comprises,
(1) applying onto the surface of the substrate to a thickness of about 0.5 to about 5 mil, an irradiation-curable silicone composition comprising,
(a) an alkenyl-substituted polydiorganosiloxane having alkenyl radicals attached to silicon by carbon-silicon bonds, where the alkenyl radicals can be in the terminal position, in the polymer backbone, or a combination thereof,
(b) a silicon hydride cross-linker, and,
(c) an amount of a photo-active cyclopentadienylplatinum (IV) compound of formula (2) which is sufficient to convert the irradiation-curable silicone composition to a tack-free state, and
(2) irradiating the surface of the applied irradiation- curable silicone composition with light in the range of 240-400 nm.
In still other of its embodiments the present invention comprises substrates coated with an irradiation-curable silicone composition and the corresponding substrates coated with the subsequently cured silicone film comprising platinum (IV) compounds included within formula (2), and any reaction products thereof which may have been formed, for example, during processing and irradiation-curing.
DETAILED DESCRIPTION OF THE INVENTION
The photo-active cyclopentadienylplatinum (IV) compounds of the present invention are shown by the following formula,
[(R
1
)
a
(R
2
)
b
Cp]Pt(R
3
)
3
(2)
where R
1
is a C
7-20
aromatic organic radical, R
2
is a C
1-22
aliphatic organic radical, R
3
is a C
1-22
aliphatic organic radical or a C
6-20
aromatic organic radical, Cp is a cyclopentadienyl radical, “a” is an integer equal to 1 to 3 inclusive, “b” is an integer equal to 0 to 3 inclusive, and the sum of a +b is equal to 1 to 4 inclusive. In one embodiment the photo-active cyclopentadienylplatinum (IV) compounds of formula (2) can be synthesized by effecting reaction between a C
7-20
aromatic-substituted cyclopentadienyl compound having the formula,
(R
1
)
a
(R
2
)
b
CpM, (3)
and a platinum (IV) compound having the formula,
XPt(R
3
)
3
(4)
where R
1
, R
2
, R
3
, Cp, “a” and “b” are as previously defined, M is a metallic anion, such as lithium, and X is an anionic leaving group, such as, but not limited to, triflate, borate, phosphate, or halogen.
Among the C
7-20
aromatic organic radicals shown by R
1
of formula (2), there are included tolyl, naphthyl, 2-benzoylnaphthalene, thioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, anthraquinone, 1-chloroanthraquinone, acetophenone, benzophenone, 9,10-dimethylanthracene, 9,10-dichloroanthracene, biphenyl, anthracenyl, phenanthryl and pyrenyl. Further, the cyclopentadienyl compound can be substituted with an &eegr;
5
-fluorenyl group. Preferred C
7-20
aromatic 10 organic radicals are naphthyl, biphenyl, anthracenyl, phenanthryl and pyrenyl.
Aliphatic organic radicals included within both R
2
and R
3
groups are C
1-22
aliphatic moieties which can independently be the same or different, and include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, allyl, aryl-substituted aliphatic moieties including benzyl and substituted benzyl, and cycloaliphatic groups including cyclopentyl and cyclohexyl. Aromatic organic radicals included within R
3
are C
6-20
aromatic moieties which can be the same or different, and include, but are not limited to, phenyl, and substituted phenyl, particularly alkyl-substituted phenyl. Mixtures of C
1-22
aliphatic moieties and C
6-20
aromatic moietie
Bennett Bernadette M.
General Electric Company
Johnson Noreen C.
McClendon Sanza L.
Seidleck James J.
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