Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Physical dimension specified
Reexamination Certificate
2001-09-24
2004-01-06
Kiliman, Leszek (Department: 1773)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Physical dimension specified
C428S204000, C428S297400, C427S397700, C427S397700, C264S021000, C264S103000, C264S129000, C264S168000
Reexamination Certificate
active
06673437
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a luminescent coating compound. In particular, this invention relates to a coating compound of binders and luminescent fibers, and to the use of this coating compound, especially to identify articles.
2. Description of Related Art
The term “luminescence” is defined as the light emission produced by gases, liquids or solids after suitable energy supply, and the emitted light can be in the visible range, in the UV range, and/or in the infrared range. Two forms of luminescence can be distinguished, specifically fluorescence and phosphorescence. For details, refer to the Roempp Lexikon Chemie, 10th edition, key word “Luminescence”, “Fluorescence” and “Phosphorescence” and to the bibliography cited there.
Coatings into which luminescent dyes or pigments have been uniformly incorporated are commercially available. Thus, cements with fluorescent dye pigments are used for optical detection of labels. However, these coatings are not used for security identifications since they are relatively nonspecific. In paper and textile coatings, their emission would moreover be overwhelmed by the whiteness (OBA) which are generally contained in them. In addition, the amounts of fluorescent dyes to be used are relatively large in this case.
Published German Patent Application Nos. 195 10 468 and 195 49 374 disclose a transparent film which fluoresces continuously in daylight, the fluorescence effect being produced by color pigments in larger amounts being incorporated into the fluorescing film, distributed uniformly over the entire film. A similar, continually fluorescing transparent adhesive film material which is dyed with larger amounts of a fluorescing dye distributed over the entire film is described in German Utility Model 91 17 086 and in European Patent No. 0 594 765.
However, the above described films are not suited for security identification, being designed to produce an optical effect which is used preferably for advertising purposes, because these films exhibit continuous luminescence which is detectable with the naked eye. Furthermore, a relatively large amount of dye pigments is necessary to produce the luminescence effect distributed uniformly over the entire film.
SUMMARY OF THE INVENTION
A primary object of this invention is to provide a system which enables identification of articles. Here, the ability of certain substances to luminesce will be used. In particular, the system will make it possible to impart a security or identification function.
The subject matter of this invention is a coating compound which contains at least one organic binder and luminescent fibers, the luminescent fibers being formed of a fiber-forming material with at least one luminescent dye or pigment distributed in it.
The coating compound in accordance with the invention can be used to identify articles of all types by applying the coating compound to the surface of these articles.
The organic binder can be binders of all types. The organic binder must, however, be chosen such that the luminescent pigments or dyes are not attacked and are not dissolved by the fibers. This also applies to other substances contained in the coating compound, especially to solvents possibly contained in the coating compound. Examples of suitable organic binders are varnishes of all types, especially clear varnish. The organic binder can also be paper or film coating slips. Furthermore, the organic binder can be cements of all types; example of the cements under consideration are contact adhesives, for example, solvent-based contact adhesives, dispersion-based contact adhesives or hot-melt adhesives. The organic binder used in the coating compound in accordance with the invention is especially a clear, i.e., transparent or essentially transparent organic binder. However, it is also possible to use cloudy to opaque binders, especially when the coating compound is applied thinly and the fibers “come out” of the coating.
The luminescent fibers used in accordance with the invention are known (see, published German Patent Application Nos. 195 39 315 and 198 02 588 and U.S. Pat. No. 5,674,437) and are commercially available. Producers of these fibers include Honeywell, Specialty Chemicals, previously Riedel-de-Haen, which markets a host of luminescent fibers under the trademark LUMILUX®, the luminescent dye pigments distributed in the fibers, depending on the molecule, emitting light of different wavelength or color (for example, fibers of type LUMILUX® Blue MF-P 831/22/3-LT, LUMILUX® Red MF-P-870/LT, LUMILUX® Yellow MF-P 833/22/3-LT).
For a long time, fibers of the aforementioned type had been incorporated into fibrous materials like paper or textiles in their manufacture; in paper production, these fibers are added to the pulp, and in textile production, to the raw material from which the fibers are spun. This results in relatively large production batches. The luminescent fibers in these products are only used as a security feature which is hard to falsify, for example, for currency. The basis of these fibers is silk, cellulose, cellulose acetate, polyamides, polyesters; they are dyed with organic or inorganic luminescent dyes (see, published German Patent Application Nos. 195 39 315 and 198 02 588 and U.S. Pat. No. 5,674,437). In the prior art, these fibers were not used to produce functional coatings.
Production of the luminescent fibers used in accordance with the invention is known from the prior art. Reference can be made once again to published German Patent Application Nos. 195 39 315 and 198 02 588 and U.S. Pat. No. 5,674,437.
In the production of luminescent fibers, the procedure is generally that the luminescent dye is added to the fiber-forming material or a solution of it and the fibers are spun from it. It is also possible to bring the fibers or the fiber-forming material into contact with a solution or dispersion of the luminescent dye (for example, by spraying, immersion, impregnation, etc.), and to dry the fibers obtained in this way.
The amount of luminescent fibers used in the coating compound in accordance with the invention and the composition of the fibers, especially the length and thickness of the fibers and the type of fiber material and the dye, are matched such that the coating process is not disturbed. On the other hand, however, it must be possible to achieve an identification function.
Generally, the coating compound according to the invention, relative to 100 parts by weight of the coating compound, contains 0.0001 to 10 parts by weight, especially 0.001 to 7.5 parts by weight, preferably 0.001 to 5 parts by weight, of luminescent fibers. The length of the luminescent fibers used in accordance with the invention can vary within wide limits and is generally in the range from 0.05 to 10 mm, especially in the range from 0.1 to 5 mm. This thickness of the luminescent fibers used can likewise vary within wide limits and is typically in the range from 1 to 1,000 microns, especially in the range from 10 to 100 microns.
The fiber-forming material can be all known fiber-forming materials if they are compatible with the coating compound of the invention. Examples of suitable fiber-forming materials are silk, cellulose, cellulose acetate, polyamides, polyesters, polyacrylates, polyolefins, polyurethanes, cotton and mixtures of the aforementioned materials. The fibers used contain the luminescent dye or the luminescent pigment typically in an amount of more than 5 to 50% by weight, especially from 7 to 40% by weight, preferably 10 to 20% by weight, relative to the total weight of the fibers.
The luminescent dye or the luminescent pigment can be of an organic or inorganic nature. In particular, the luminescent dye or luminescent pigment can at least partially exhibit a luminescent effect when excited with ultraviolet radiation. Here, the luminescent effect can be based on fluorescence or phosphorescence.
DETAILED DESCRIPTION OF THE INVENTION
According to one embodiment of the invention the luminescent dye or luminescent pigment is
Frigge Christoph
Kohla Michael
Jackstädt GmbH
Kiliman Leszek
Nixon & Peabody LLP
Safran David S.
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