Radiant energy – Luminophor irradiation – Methods
Reexamination Certificate
1999-01-13
2002-02-05
Epps, Georgia (Department: 2878)
Radiant energy
Luminophor irradiation
Methods
C252S301350, C252S301160
Reexamination Certificate
active
06344654
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for preparing fluorescent polymers, and coating compositions containing such fluorescent polymers. In particular, the present method relates to the inclusion of fluorescent compounds in the preparation of polymers useful in coating compositions such that the resultant compositions are detectable by fluorescent means.
A method for preparing a fluorescent polymer is disclosed in U.S. Pat. No. 5,125,929 (Amey). There, a Michael addition reaction produces a linear aminoacid polymer which is fluorescent. In this case, the fluorescence is produced by the polymer backbone. This method is limited by the nature of its chemistry. Moreover, most polymers produced by a Michael addition reaction will not have fluorescence.
U.S. Pat. No. 5,043,406 (Fong) discloses a method for incorporating fluorescent moieties into acrylamide polymers by copolymerizing acrylamide monomers with monomers containing pendant fluorescent moieties. The principal limitation to this method is the lack of commercially available monomers containing pendant fluorescent moieties. Even if other monomers could be modified to incorporate pendant fluorescent moieties, the increased cost of doing so would make the cost of such fluorescent polymers prohibitive.
Both the methods described by Amey and Fong are limited in applicability, either by virtue of the nature of the chemistry involved, or by the lack of available fluorescent starting materials. What is needed is a method for incorporating fluorescence into a broad variety of polymers, thus permitting broader usage of such fluorescent polymers.
STATEMENT OF THE INVENTION
A first embodiment of the present invention is directed to a method for preparing a fluorescent polymer, comprising copolymerizing one or more ethylenically unsaturated monomers with a fluorescent compound selected from the group consisting of polynuclear aromatic hydrocarbons and their substituted aromatic derivatives; wherein the resultant polymer contains a fluorescent group.
A second embodiment of the present invention is directed to a coating composition having enhanced UV durability, comprising a fluorescent polymer prepared by copolymerizing an ethylenically unsaturated monomer with a fluorescent compound selected from the group consisting of: polynuclear aromatic hydrocarbons and their substituted aromatic derivatives; and ethylenically unsaturated monomers having pendant fluorescent functionality.
A third embodiment of the present invention is directed to a method for identifying and quantifying the amount, if any, of fluorescent polymer contained in a coating composition, such method comprising the steps of: (a) obtaining a sample of the coating composition or resulting coating to be tested; (b) detecting the fluorescence; and (c) measuring the intensity or the wavelength of the fluorescence of the fluorescent polymer contained in the sample.
DETAILED DESCRIPTION OF THE INVENTION
As used in this specification, the following terms have the following definitions, unless the context clearly indicates otherwise. “Latex” or “latex composition” refers to a dispersion of a water-insoluble polymer which may be prepared by conventional polymerization techniques such as, for example, by emulsion polymerization. “Latex” also refers to polymer dispersed in an aqueous composition, wherein the polymer can be prepared directly in the aqueous medium, or first prepared in a non-aqueous medium (e.g., using solution polymerization) and then subsequently dispersed in the aqueous medium. “Fluorescent” or “fluorescence” refers to a compound which, when excited by radiation, occupies a second excited state which is said to “fluoresce” or emit radiation at a lower energy (longer wavelength) than the original excited state. “Chromophore” refers to a compound having fluorescence which is capable of being covalently attached to a polymer. “Backbone” refers to the main chain of a polymer exclusive of pendant or end groups; “pendant” refers to a group suspended from the main chain of a polymer; and “end” refers to a group suspended from the end of a polymer chain. “PVC” used in reference to paint means pigment volume concentration. The terms “group” and “moiety” are used interchangeably. The following abbreviations are used: cm=centimeter, mm=millimeters, nm=nanometers, mL=milliliters, HPLC=high pressure liquid chromatography, UV=ultraviolet, ai=active ingredient. Ranges specified are to be read as inclusive, unless specifically identified otherwise.
It has now been discovered that certain weak polymerization inhibitors can be used to incorporate fluorescent moieties into a broad variety of polymers by free radical copolymerization of the polymerization inhibitors with the appropriate monomers. These polymerization inhibitors can be broadly classified as polynuclear aromatic hydrocarbons. Examples of such polynuclear aromatic hydrocarbon clromophores can be found in Russian Patent 478839 (Gladyshev) and “Polymerization Inhibition by Aromatic Compounds,”
J. Polymer Sci.,
52:31 (1961). It has also been found that substituted aromatic derivatives of such polynuclear aromatic hydrocarbons can also be used in this fashion. Such derivatives are those wherein the polynuclear aromatic hydrocarbon is substituted without loss of aromaticity. These substituents include but are not limited to: C
1-12
branched or straight chain alkyl or aryl groups optionally substituted with heteroatoms; carboxylic acids and esters thereof; sulfonic acids and derivatives thereof; cyano groups; and halogens. Preferred polynuclear aromatic hydrocarbons include: naphthalene, anthracene, phenanthrene, fluoranthene, acridine, carbazole, pyrene, chrysene, triphenylene, perylene, and their substituted aromatic derivatives. It is especially preferred to use naphthalene, anthracene, phenanthrene, fluoranthene, and their substituted aromatic derivatives. Combinations of chromophores can also be used.
In another embodiment of the present invention, the fluorescent polymers are used as markers for product identification. In this respect, other types of fluorescent polymers can be utilized. For example, such polymers can be prepared by copolymerizing the appropriate monomers with an ethylenically unsaturated monomer having pendant fluorescent functionality.
Detection of the fluorescent polymers is accomplished by taking a sample of the coating composition or the resulting (applied) coating, and analyzing the sample to determine the fluorescence wavelength, and the intensity of the fluorescence emission. HPLC or GPC analysis may be used to determine whether or not the fluorescent moiety is covalently attached to the polymer. (See, for example, S. Sosnowski et al.,
J. Polvmer Sci.,
Part A: Polymer Chemistry 32:1497 (1994).) If a sample of the applied coating is used, it may be useful to extract the polymer from the other coating components prior to analysis, in accordance with methods known to those skilled in the art.
Examples of ethylenically unsaturated monomers having pendant fluorescent functionality can be found in: U.S. Pat. No. 5,043,406 (Fong), S. Sosnowski et al.,
J. Polvmer Sci
Part A: Polymer Chemistry 32:1497 (1994), C. L. Zhao et al.,
Macromolecules,
23:4082 (1990), E. M. Boczar et al.,
Macromolecules,
26:5772 (1993), M. A. Fox et al.,
Macromolecules,
23:4533 (1990), and C. Simionescu et al.,
J. Polymer Sci.,
23:2089 (1985). Preferred ethylenically unsaturated monomers having pendant fluorescent functionality include: naphthylmethyl methacrylate, naphthylethyl methacrylate, 9-anthryl methacrylate, 9-anthrylmethyl methacrylate, 2-(9-anthryl)ethyl methacrylate, 1′-(9-anthryl)ethyl methacrylate, 3-hydroxy-2-methylene-3-(1-naphthyl)propionic acid, N-dibenzosuberenyl acrylamide, (9-phenanthryl)methyl methacrylate, and 9-vinyl phenanthrene. It is especially preferred to use naphthylethyl methacrylate, 9-anthryl methacrylate, 3-hydroxy-2-methylene-3-(1-naphthylpropionic acid, (9-phenanthryl)methyl methacrylate, 9-vinyl
Epps Georgia
Hanig Richard
Rohm and Haas Company
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