Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1999-01-15
2002-10-01
Berman, Susan (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S015000, C522S025000, C522S028000, C522S168000, C522S169000, C522S170000, C522S181000, C522S173000, C522S908000, C523S115000, C523S116000, C523S117000, C433S228100
Reexamination Certificate
active
06458865
ABSTRACT:
FIELD OF THE INVENTION
This invention relates in general to compositions of matter and, more particularly, to compositions that include a vinyl ether and a photoinitiator system. These compositions may also include an epoxide, a polyol, and/or a spiroorthocarbonate (SOC), which may be one of the novel spiroorthocarbonates disclosed herein. The polymerizable compositions of the present invention are useful for a variety of applications, including for use as dental materials such as adhesives and composites.
BACKGROUND OF THE INVENTION
Many types of monomers undergo shrinkage during polymerization to a degree that makes them generally unsuited for use in numerous applications, including for use as stress-free composites, high-strength adhesives, and precision castings. As an example, when such monomers are used in composites which contain inorganic fillers, the polymeric matrix is subject to failure when the polymer shrinks and pulls away from the filler particles. Failure of the composite can also occur when the matrix ruptures as a result of voids or micro cracks which form in the matrix during polymerization shrinkage.
Polymeric matrices commonly employed in dental materials such as adhesives and composites are based on 2,2′-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)]phenyl propane (BisGMA). A significant problem associated with the use of this monomer in dental applications is the shrinkage which occurs as the monomer is polymerized. The BisGMA monomer itself typically experiences high shrinkage, and when a low viscosity reactive diluent is combined with the monomer, the shrinkage may even be higher. The adverse effects of such shrinkage are believed to include increased postoperative sensitivity, the formation of marginal gaps between the dental restoration and the cavity wall, cracking of the restoration, and microleakage and potential failure of the restoration.
The discovery that spiroorthocarbonates may undergo reduced polymerization contraction and possibly polymerization expansion has led to the suggestion of their use in reinforced composites, including as dental materials. Spiroorthocarbonates are esters of orthocarboxylic acid and have four oxygen atoms bonded to a single carbon atom, with the carbon atom being common to two ring systems. The expansion of the spiroorthocarbonates on polymerization is attributed to a double spiro-cyclic ring opening of the spiroorthocarbonates, resulting in the breaking of two covalent bonds to form one new bond.
Initial attempts to form a homogeneous polymer matrix from certain spiroorthocarbonates and BisGMA resin mixtures proved unsuccessful because of the incomplete polymerization of the spiroorthocarbonates. Thompson et al., J. Dental Research 58:15221532 (1979). More recent studies demonstrated that homogeneous mixtures of other spiroorthocarbonates and BisGMA could be obtained. Stansbury, J. Dental Research 70:527; Abstract No. 2088 (1991).
The photocationic-initiated expansion polymerization of alicyclic spiroorthocarbonate monomers and the potential use of the resulting polymers in dental materials have been previously reported by some of the present inventors, with others. Byerley et al., Dent. Mater. 8:345-350 (1992). The specific spiroorthocarbonates identified by Byerley et al. include cis/cis, cis/trans, and trans/trans configurational isomers of 2,3,8,9-di(tetramethylene)-1,5,7,11-tetraoxaspiro[5.5]undecane. These spiroorthocarbonates were determined to undergo an expansion of 3.5% during homopolymerization and demonstrated acceptable cytotoxicity and genotoxicity properties, making them promising components of composite resin matrix materials.
Some of the present inventors, with others, have also previously reported on the preparation of a copolymer of an alicyclic spiroorthocarbonate and an unidentified monofunctional epoxide, with the observation that there were no indications of the formation of small ring compounds as polymerization by-products. Byerley et al., J. Dental Research 69:263; Abstract No. 1233 (1990). The copolymerization of trans/trans-2,3,8,9-di(tetramethylene)-1,5,7,11-tetraoxaspiro[5.5]undecane and commercially available multifunctional epoxides was also disclosed in a paper presented by Byerley et al., Abstract No. 1233, cited above. However, no physical or mechanical properties, including percentage shrinkage, of the copolymer compositions were disclosed. Still further, spiroorthocarbonate copolymers have been created that are capable of yielding a hard, non-shrinking matrix resin. These copolymers include a trans/trans-2,3,8,9-di(tetramethylene)-1,5,7,11-tetraoxaspiro[5.5]undecane spiroorthocarbonate, a polymerizable epoxy resin, and a hydroxyl containing material, as described in U.S. Pat. No. 5,808,108.
A polymeric composition that includes a vinyl ether, a diepoxide, a polyol, and a photoinitiator system including an iodonium salt and a visible light sensitizer has previously been disclosed by one of the present inventors. Eick et al., J. Dental Research, 77B:639; Abstract No. 63 (1998). This photoinitiator system is similar to that disclosed in PCT/US95/14098, but does not utilize an electron donor compound. The reaction rate for forming this disclosed polymeric composition has subsequently been determined to be very slow, making the composition generally unsuited for use in applications requiring faster reaction rates.
An epoxide/polyol polymeric composition that includes a photoinitiator system comprising an iodonium salt, a visible light sensitizer, and an electron donor compound is disclosed by one of the present inventors, with another, in PCT application Nos. PCT/US98/04458 ('458 application) and PCT/US98/04029 ('029 application). The '458 application further suggests that other cationically polymerizable polymers, such as vinyl ethers, can be incorporated into the epoxide/polyol polymeric composition. However, this application does not suggest that vinyl ether may be a substantial component of the composition, but only an optional additive.
The results of an attempted block polymerization of a living poly (spiroorthocarbonate) and a vinyl ether are disclosed by T. Endo et al. in Macromolecules, vol. 21, pp. 1186-1187, in an article entitled “Polymerization and Block Copolymerization Initiated by Unusually Stable Living Propagating Species Formed in the Cationic Polymerization of Spiro Ortho Carbonate” (1988). The disclosed reactions required heat and a considerable amount of time for polymerization. In addition, homopolymerization of n-butyl vinyl ether was observed. This article does not disclose using a ternary photoinitiator system to promote polymerization.
A diepoxy spiroorthocarbonate, namely, 3,23-dioxatrispiro[tricyclo[3.2.1.0<2,4>]octane-6,5′-1,3-dioxane-2′2″-1,3-dioxane-5″,7′″-tricyclo[3.2.1.0<2,4>octane], is disclosed in a book entitled, “Expanding Monomers, Synthesis, Characterization and Applications,” edited by R. J. Sadhir and R. M. Luck, CRC Press, Boca Raton (1992), pp. 329-332. This compound is purported to have the following structure:
The book does not suggest that vinyl ethers may be combined with this spiroorthocarbonate, and the polymerization of the compound is reported to require extended reaction times and high temperatures (i.e., 1 hr/110° C., 1 hr/125° C., 4 hr/150° C., and 8 hr/150° C.). The disclosed polymerizations involved using a cationic initiator, but there is no suggestion that a visible light photoinitiator system could be used. The extended reaction times, elevated temperatures, and reaction conditions make the disclosed polymerizable composition generally unsuited for many applications, including use as dental materials.
Despite the advances resulting from the above-noted polymeric compositions and SOCs, a need still exists for polymerizable compositions having properties desirable for use as dental materials such as adhesives and composites, as well as other applications.
SUMMARY OF THE INVENTION
In one aspect,
Chappelow Cecil C.
Eick J. David
Oxman Joel D.
Pinzino Charles S.
Berman Susan
Curators of the University of Missouri
Stinson Morrison & Hecker LLP
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