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
2000-05-09
2003-03-18
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, C528S014000, C528S018000, C528S035000, C528S037000, C556S431000, C556S433000, C556S434000, C556S435000, C556S464000, C427S002240, C606S001000, C523S105000
Reexamination Certificate
active
06534587
ABSTRACT:
BACKGROUND OF THE INVENTION
Silicones (i.e., organosiloxanes) are polymers containing alternating silicon and oxygen atoms in the backbone with various organic groups attached to the silicon atoms. Silalkylenesiloxane copolymers include alkylene backbone units without unsaturation and also include monovalent hydrocarbon groups attached to silicone atoms. Both silicones and silalkylenesiloxanes are useful materials for a wide variety of applications (e.g., rubbers, adhesives, sealing agents, release coatings, antifoam agents). Because of their biocompatibility, silicones present a low risk of unfavorable biological reactions and have therefore gained the medical industry's recognition. Such materials are useful in a wide variety of medical devices. There are, however, limited materials available for medical device applications. In addition, there is a need for improved silicone materials that can be used in the medical industry, particularly those with good strength and tear resistance.
Prior to the present invention, silalkylenesiloxane copolymers have been prepared by three methods. Ring opening polymerization of cyclic silethylenesiloxane is disclosed in U.S. Pat. No. 5,117,025 (Takago et al.). Condensation polymerization of silanol terminated silalkylene oligomers is disclosed in U.S. Pat. No. 5,386,049 (Kishita et al.). Step growth hydrosilylation polymerization between a hydride terminated organosiloxane and an unsaturated aliphatic hydrocarbon that contains 2 carbon-carbon double bonds or one carbon-carbon double bond and one carbon-carbon triple bond is disclosed in U.S. Pat. No. 5,442,083 (Kobayashi).
U.S. Pat. No. 5,442,083 (Kobayashi) states that the ring opening polymerization of cyclic silethylenesiloxane is not advantagous for producing silalkylenesiloxane copolymers. As reported in Andrianov et al.,
Inst. Of Heteroorganic Cpds., p.
661, translated from
Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya,
No. 4, pp. 739-44 (1971), a partial depolymerization occurs in this method, which therefore leads to reduced yields of the silalkylenesiloxane copolymer.
Step growth condensation polymerization of silanol terminated fluids yields copolymers that have silanol end groups. To make the copolymer end-functional, for example, vinyidimethylsilyl terminated, another synthetic step is required. This is a disadvantage. In addition, degrees of polymerization (Dp) from step growth silanol condensation polymerizations of disilanolsilalkylene compounds have been reported to be no greater than 180. See, U.S. Pat. No. 5,386,049 (Kishita et al.) and Benouargha et al.,
Eur. Polym. J.,
33, p. 1117 (1997). This is a disadvantage.
Hydrosilylation step growth polymerization as a method of silalkylenesiloxane copolymer synthesis also contains inherent disadvantages. In order to produce high Dp copolymer, the stoichiometry of the silylhydride and unsaturated hydrocarbon moieties must be as close to 1:1 as possible. Side reactions which disturb this balance limit the Dp of said copolymer by creating terminating groups on unsaturated hydrocarbon monomers. For example, it is known in the art that transition metal catalysts typically used for hydrosilylation reactions can cause the isomerization of a terminal carbon-carbon double bond to an internal position. See, Harrod et al.,
Organic Synthesis via Metal Carbonyls,
2, John Wiley & Sons, New York, p. 673 (1977), Cundy et al.,
Adv. Organometallic Chem.,
2, p. 253 (1973), and Speier,
Adv. Organometallic Chem.,
17, p. 407 (1979). This is a disadvantage. This isomerization renders the monomers less suceptible to hydrosilylation.
Silalkylenesiloxane copolymers having a Dp as high as 10,000 are disclosed in U.S. Pat. No. 5,484,868 (Kobayashi). However, step growth hydrosilylation polymerization was the method used to produce the copolymers and no examples were provided which would circumvent the disadvantages outlined above.
The following lists of documents disclose information regarding siloxane compounds.
TABLE 1a
Patents
U.S. Pat. No.
Inventor(s)
Issue Date
5,117,025
Takago et al.
05/26/92
5,239,034
Takago et al.
08/24/93
5,241,034
Herzig et al.
08/31/93
5,386,007
Herzig et al.
01/31/95
5,386,049
Kishita et al.
01/31/95
5,442,083
Kobayashi
08/15/95
5,484,868
Kobayashi
01/16/96
5,516,832
Kennan et al.
05/14/96
5,525,696
Herzig et al.
06/11/96
5,531,929
Kobayashi
07/02/96
5,581,008
Kobayashi
12/03/96
5,696,211
Chung et al.
12/09/97
5,703,190
Dauth et al.
12/30/97
TABLE 1b
Non-U.S. Patents
Patent No.
Country
Publication Date
EP 0 709 403 A1
EPO
05/01/96
WO 96/20964
PCT
07/11/96
WO 96/35732
PCT
11/14/96
TABLE 1c.
Nonpatent Documents
Andrianov et al., “Polymerization of 2,2,6,6-Tetramethyl-1-oxa-2,6-
disilacyclohexane,” Inst. of Heteroorganic Cpds., p. 661, Translated from
Izvestiva Akademii Nauk SSSR, Seriya Khimicheskava, No. 4, pp. 739-
44 (1971)
Benouargha et al., “Hybrid Silalkylene Polysiloxanes: Synthesis and
Thermal Properties”, Eur. Polym. J., 33, pp. 1117-1124 (1997).
Cundy et al., “Organometallic Complexes with Silicon-Transition Metal or
Silicon-Carbon-Transition Metal Bonds”, Advances in Organometallic
Chemistry, Academic Press, New York (1973), pp. 253-311.
Dvornic et al., “Polymerization by Hydrosilation. 2. Preparation and
Characterization of High Molecular Weight Poly[(1,1,3,3-
tetramethyldisiloxanyl)ethylene] from 1,3-Dihydridotetramethyldisiloxane
and 1,3-Divinyltetramethyldisiloxane”, Macromolecules, 27, pp. 7575-
7580 (1994).
Harrod et al., “Hydrosilation Catalyzed by Group VII Complexes”,
Organic Synthesies via Metal Carbonyls, John Wiley & Sons, New York
(1977), pp. 673-705.
Marciniec et al., Comprehensive Handbook on Hydrosilylation,
Pergamon Press, Ltd; Tarrytown, New York; 1992; pp. 35-38.
Odian, Principles of Polymerization, John Wiley & Sons, New York
(1981), pages 82-87.
Speier, “Homogeneous Catalysis of Hydrosilation by Transition Metals”,
Advances in Organometallic Chemistry, Academic Press, New York
(1979), pp.407-447.
All patents, patent applications, and publications listed above are incorporated by reference in their respective entireties. As those of ordinary skill in the art will appreciate readily upon reading the application, certain of the information disclosed in the above-listed documents may be utilized in the monomers, polymers, their preparation methods, and the devices disclosed and claimed herein.
SUMMARY OF THE INVENTION
The present invention has certain objects. That is, various embodiments of the present invention provide solutions and advantages to one or more of the problems existing in the prior art with respect to the preparation and properties of siloxanes, and particularly, silalkylenesiloxanes. Certain of these problems are discussed above. The materials and methods of the present invention address one or more of these problems.
The present invention provides symmetric cyclic silalkylenesiloxane monomers having the following formula:
wherein p is at least 6, and v is at least 1, and each R
1
and R
2
group is independently a monovalent organic group. Alternatively, the present invention provides such monomers wherein p is at least 2 and v is at least 2. Such symmetric monomers include the same value for p in each repeat unit.
The present invention also provides asymmetric cyclic silalkylenesiloxane monomers having the following formula:
wherein p and q are each at least 2, v and w are each at least 1, with the proviso that q does not equal p for at least one set of silalkylenesiloxane repeat units, and each R
1
and R
2
group is independently a monovalent organic group. Such asymmetric monomers can include values for p that are the same or different in the various repeat units, and values for q that are the same or different in the various repeat units.
The present invention also provides silalkylenesiloxane copolymers of the formula:
wherein p is at least 2, b is at least 1, the sum of b and c is greater than 300, and each R group is independently a monovalent organic group. These copolymers can be crosslinked and/or reinforced with a silica filler. Preferabl
Di Domenico Edward
Tapsak Mark A.
Berry Thomas
Collier Kenneth
Medtronic Inc
Robertson Jeffrey B.
Wolde-Michael Girma
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