Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-08-20
2002-01-29
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C528S373000, C528S376000, C526S289000, C526S307100, C525S212000, C252S586000
Reexamination Certificate
active
06342571
ABSTRACT:
DESCRIPTION OF THE INVENTION
The present invention relates to polymerizable organic compositions and polymerizates having a refractive index of at least 1.57 and an Abbe number of at least 33, which are prepared from such compositions. More particularly, the present invention relates to certain polymerizable organic compositions comprising a mixture of thio(meth)acrylate functional monomers, an aromatic monomer having at least two vinyl groups, a polythiol monomer having at least two thiol groups, and a comonomer selected from an anhydride monomer having at least one ethylenically unsaturated group and/or a monomer having at least three (meth)acryloyl groups.
Polymeric materials, such as plastics, have been developed as alternatives and replacements for silica based inorganic glass in applications such as, optical lenses, fiber optics, windows and automotive, nautical and aviation transparencies. These polymeric materials can provide advantages relative to glass, including, shatter resistance, lighter weight for a given application, ease of molding and ease of dying. Representative examples of such polymeric materials include, poly(methyl methacrylate), polycarbonate and poly(diethylene glycol bis(allylcarbonate)).
The refractive indices of many polymeric materials are generally lower than that of high index glass. For example, the refractive index of poly(diethylene glycol bis(allylcarbonate)) is about 1.50, compared to that of high index glass, which can range, for example, from 1.60 to 1.80. When fabricating lenses to correct a given degree of visual defect, e.g., a correction for myopia, the use of a polymeric material having a lower refractive index will require a thicker lens relative to a material having a higher refractive index, e.g., high index glass. If the degree of correction required is substantial, e.g., in the case of severe myopia, a lens fabricated from a low index polymeric material can become so thick as to negate any benefit of reduction in weight relative to an equivalent degree of correction obtained from a higher refractive index lens, e.g., a high index glass lens. In addition, thicker optical lenses are not aesthetically desirable.
Polymeric materials prepared from the polymerization of monomers containing aromatic rings typically have high refractive indices. However, articles, such as optical lenses, prepared from such high index polymeric materials generally have lower Abbe numbers (also known as nu-values). Lower Abbe numbers are indicative of an increasing level of chromatic dispersion, which is typically manifested as an optical distortion at or near the rim of the lens.
More recently, polymeric materials having a combination of high refractive indices, e.g., of at least 1.57, and low levels of chromatic dispersion, e.g., having Abbe numbers of at least 33, have been prepared from monomers containing sulfur atoms. While possessing a desirable combination of high refractive indices and Abbe numbers, such sulfur atom containing polymeric materials often have physical properties, e.g., heat and impact resistance, that are in some instances less than desirable. For example, the impact resistance of an optical lens is a particularly important safety related physical property, and improvements in impact resistance of optical lenses prepared from sulfur-containing polymeric materials are accordingly desirable.
There is, therefore, a need for the continued development of transparent polymerizates, in particular optical lenses, that possess a combination of high refractive index and adequately high Abbe numbers, e.g., preferably at least 33 and more preferably at least 35. It is further desirable that these polymeric materials also possess improved physical properties, such as thermal properties and impact resistance.
U.S. Pat. No. 5,917,006 describes a polymerizable organic composition comprising an aromatic monomer having at least two vinyl groups, e.g., divinyl benzene, a polythiol monomer having at least two thiol groups, e.g., pentaerythritol tetrakis(2-mercaptoacetate), and an anhydride monomer having at least one ethylenically unsaturated group, e.g., methacrylic anhydride. The '006 patent does not describe compositions comprising thioacrylate and/or thiomethacrylate functional monomers.
U.S. patent application Ser. No. 09/037,108, filed Mar. 9, 1998 (now U.S. Pat. No. 5,976,422) describes a polymerizable organic composition comprising at least one polymerizable monomer having at least two ethylenically unsaturated groups, e.g., divinyl benzene, a novel polythiol monomer, e.g., thioglycerol bis(2-mercaptoacetate), and optionally a monoethylenically unsaturated monomer, e.g., phenoxyethyl methacrylate, and/or an anhydride monomer, e.g., methacrylic anhydride. The compositions of the '108 application are not described as comprising thioacrylate and/or thiomethacrylate functional monomers.
U.S. Pat. No. 5,384,379 describes sulfur-containing polymethacrylates produced by the radical polymerization of the unrefined products resulting from the synthesis of a thio(meth)acrylic acid ester monomer. The '379 patent describes the radical polymerization of a monomer component having two thio(meth)acrylic acid ester groups and a chain extended monomer component having two thio(meth)acrylic acid ester groups.
U.S. Pat. No. 5,422,422 describes a high refractive index plastic produced by the reaction of an alkylthiol containing at least two thiol groups, and an alkylpolythiol ester, which contains at least two thiol groups esterified with (meth)acrylic acid. U.S. Pat. No. 4,931,521 describes a process for producing a high refractive index optical material from the radical polymerization of at least one polyfunctional thioacrylate or polyfunctional thiomethacrylate and optionally at least one other radically polymerizable monomer.
In accordance with the present invention, there is provided a polymerizable composition comprising:
(a) a mixture of thio(meth)acrylate functional monomers comprising,
(i) a first thio(meth)acrylate functional monomer represented by the following general formula I,
in which R
1
is hydrogen or methyl, and Q is a divalent linking group selected from linear or branched C
2
-C
12
alkylene, C
4
-C
12
cyclic alkylene, C
6
-C
14
arylene and C
7
-C
26
alkarylene, the carbon chains of Q may optionally contain at least one linkage selected from the group consisting of ether, thioether and combinations thereof; and
(ii) a second thio(meth)acrylate functional monomer represented by the following general formula II,
in which R
1
and Q have the same meanings as described for monomer (a)(i), and u is an integer from 1 to 10, e.g., u may be an integer selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and combinations thereof;
(b) an aromatic monomer having at least two vinyl groups;
(c) a polythiol monomer having at least two thiol groups; and
(d) a comonomer selected from,
(i) an anhydride monomer having at least one ethylenically unsaturated group;
(ii) a monomer having at least three (meth)acryloyl groups represented by the following general formula III,
in which R
12
is a polyvalent radical of a polyol, R
13
is hydrogen or methyl, and k is a whole number from 3 to 6; and
(iii) mixtures of monomers (d)(i) and (d)(ii), wherein the amount of each monomer and comonomer are selected such that a polymerizate of said polymerizable composition has a refractive index of at least 1.57, as determined in accordance with American Standard Test Method (ASTM) number D542-95, and an Abbe number of at least 33, as determined using an appropriate instrument, e.g., a Bausch & Lomb ABBE-3L Refractometer.
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.”
DETAILED DESCRIPTION OF THE INVENTION
Polymerizable compositions-according to the present invention comprise a mixture of thio(meth)acrylate functional monomers (a)(
Freeman T. Edwin
Herold Robert D.
Okoroafor Michael O.
Smith Robert A.
Marmo Carol A.
Morris George D.
PPG Industries Ohio Inc.
Wu David W.
Zalukaeva Tanya
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