Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-06-19
2001-07-17
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S281000, C526S282000, C526S319000, C526S321000
Reexamination Certificate
active
06262211
ABSTRACT:
DESCRIPTION OF THE INVENTION
The present invention relates to polymerizable organic compositions and polymerizates prepared from such compositions. More particularly, the present invention relates to certain polymerizable organic compositions comprising a polyol(allyl carbonate) and an allyl ester terminated nonaromatic polyester oligomer, and polymerizates obtained from said organic compositions that are substantially free of tinting defects.
Polymerizable organic compositions based on polyol(allyl carbonate), particularly diethylene glycol bis(allyl carbonate), and polymerizates obtained therefrom are well known in the art. Polymerizates of polymerizable organic compositions based on homopolymers of diethylene glycol bis(allyl carbonate) possess excellent clarity, good flexibility and abrasion resistance, examples of which include, ophthalmic lenses, sunglasses, and automotive and aircraft transparencies. It has been observed that tinting of polymerizates prepared from such compositions by surface impregnation of dyes can in certain instances result in an uneven tinting of the surface. Such uneven tinting is referred to as tinting failure.
When tinting failure occurs, it is often manifested as visually observable defects on the tinted surface(s) of the polymerizate, which are commonly referred to as, for example, “ferns” or “moons.” In the case of tinted ophthalmic lenses, such as tinted ophthalmic lenses having a positive diopter, i.e., plus lenses, and non-corrective lenses, e.g., sunglasses, such tinting failure often results in rejection and scrapping of the tinted lens.
A common method of producing ophthalmic lenses involves the use of molds, the interior dimensions of which are fabricated to allow the casting of lenses that provide a predetermined degree of optical correction, e.g., a correction for myopia. Such a production method produces lenses that require a minimum of post-casting preparation, e.g., grinding to a desired degree of visual correction. This production method requires that the polymerizable composition from which the lenses are cast have a known and tightly controlled refractive index. If the refractive index of a reformulated polymerizable composition charged to the molds changes significantly, e.g., increases by more than 0.006 units of refractive index, then the resulting cast lens will not have the desired degree of optical correction and may either be scrapped or require additional post-casting work, e.g., grinding.
Polymerizates obtained from polymerizable organic compositions comprising polyol(allyl carbonate) monomers, and in particular diethylene glycol bis(allyl carbonate) monomer, are commonly referred to as low index materials having refractive indices of from about 1.48 through 1.53, e.g., from 1.49 to 1.50. In light of the above described production process, it is desirable that additives and radically polymerizable comonomers and oligomers used to reformulate such polymerizable compositions not substantially alter, e.g., increase, the refractive index of the resulting polymerizate.
It is accordingly desirable to identify new polymerizable organic compositions comprising polyol(allyl carbonate) monomers that can be used to prepare polymerizates that are substantially free of defects due to tinting failure. It is further desirable that these new compositions have refractive indices that are substantially equivalent to those of the corresponding original compositions comprising polyol(allyl carbonate) monomer.
U.S. Pat. No. 5,380,809 describes a composition for an optical material consisting essentially of a polyallyl carbonate of linear or branched alkylene glycols, an allyl ester oligomer having allyl ester groups at the terminal ends thereof and a main chain derived from an alicyclic dicarboxylic acid and a polyhydric saturated alcohol, and optionally a third monomer, e.g., a diallyl ester. To achieve a desirable balance of viscosity and shrinkage ratio, the allyl ester oligomer is disclosed as being present in the composition in an amount of from 20 percent to 70 percent by weight.
International publication number WO 99/17137 describes ophthalmic lenses comprising the cured product of a composition of poly(allyl carbonate) of a polyhydroxy alcohol, at least one radical initiator, and a cyclohexyl diallyl ester oligomer. The cyclohexyl diallyl ester oligomer is described in WO 99/17137 as being present in the composition in an amount of 0.05 to 60 weight percent.
It has now been discovered that cured polymerizates prepared from polymerizable organic compositions of the present invention are substantially free of defects due to tinting failure, and have refractive indices that are substantially equivalent to comparative original polyol(allyl carbonate) compositions. In accordance with the present invention, there is provided a polymerizable organic composition comprising:
(a) a radically polymerizable monomer represented by the following general formula I,
R—[—O—C(O)—O—R
1
]
i
I
wherein R is a radical derived from a polyol having two or more hydroxy groups, R
1
is a radical derived from an allyl or substituted allyl group and i is a whole number from 2 to 4; and
(b) from 0.1 percent by weight to 10 percent by weight, based on the total weight of radically polymerizable components of the polymerizable organic composition, of a polyester oligomer having terminal allyl ester groups represented by the following general formula II,
wherein R
1
has the same meaning as that described for monomer (a), m is a whole number of from 1 to 6, X is a polyvalent linking group derived from at least one polyol selected from polyols having m+1 hydroxy groups and from 2 to 30 carbon atoms, Y is a divalent linking group selected from the group consisting of the following representative general formulas, consisting of the following representative general formulas III through VII,
and mixtures thereof, and n is a number of from 1 to 100.
The features that characterize the present invention are pointed out with particularity in the claims, which are annexed to and form a part of this disclosure. These and other features of the invention, its operating advantages and the specific objects obtained by its use will be more fully understood from the following detailed description and the accompanying illustrative drawing.
Other than in the operating examples, or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions, etc. used in the specification and claims are to be understood as modified in all instances by the term “about.”
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Clontz Charles C.
Okoroafor Michael O.
Smith Robert A.
Someki Noriyuki
Franks James R.
Marmo Carol A.
Pezzuto Helen L.
PPG Industries Ohio Inc.
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