Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Reexamination Certificate
2000-08-23
2003-12-16
Kiliman, Leszek (Department: 1773)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
C428S403000, C428S407000, C428S690000, C428S537500, C162S140000, C162S162000, C427S157000
Reexamination Certificate
active
06663960
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to fluorescent particles, a process for producing the fluorescent particles, and anti-falsification paper using the fluorescent particles.
BACKGROUND ART
Various kinds of anti-falsification paper containing granular, fibrous or chipped materials having the property of emitting a visible light with a specific wavelength upon irradiation with ultraviolet rays (the property of emitting fluorescence) are known. This anti-falsification paper is characterized in that upon irradiation with ultraviolet rays such as black light, a fluorescent material contained in the paper emits a light with a specific wavelength in the visible-light range, and the specific shape of the fluorescent material is detected whereby whether the paper is falsified or not can be judged.
With respect to anti-falsification paper into which a granular fluorescent material was incorporated, the present applicant proposed, in Japanese Utility Model Laid-Open No. 6500/1994 (Japanese Utility Model Application No. 51094/1992), anti-falsification paper into which fluorescent particles produced by coating paper with a material fluorescing upon irradiation with ultraviolet rays and then shredding the coated paper are incorporated.
Further, anti-falsification paper prepared by fixing an ionic fluorescent dyestuff onto special ionic and heat resistant starch particles and incorporating the starch particles into paper was proposed by the present applicant in Japanese Patent Application No. 23904/1998.
In addition, anti-falsification paper prepared by coating the surface of autohesive particles by a high-speed air flow impact method with a water-insoluble pigment fluorescing upon irradiation with ultraviolet rays and then incorporating the particles into paper was proposed by the present applicant in Japanese Patent Application No. 92477/1998.
The above-described prior art techniques are directed to anti-falsification paper prepared by incorporating a granular fluorescent material in paper. In the anti-falsification paper proposed in Japanese Utility Model Laid-Open No. 6500/1994 among the prior art techniques described above, the fluorescent particles seem to be present in the form of amorphous and fine flocks in the paper, but it is difficult to regulate the size of these particles, and there is the problem that unnecessarily large flocks and unnecessarily small flocks are contained in the paper.
Since the anti-falsification paper proposed in Japanese Patent Application No. 23904/1998 makes use of fluorescent particles using a fluorescent dyestuff, there is the problem that the light resistance is inevitably worsened as compared with fluorescent particles using a fluorescent pigment, and the intensity of fluorescing upon irradiation with ultraviolet rays is also low. Further, there is also the problem that the hue of fluorescence is limited.
Although the fluorescent particles used in the anti-falsification paper proposed in Japanese Patent Application No. 92477/1998 have the advantage that they are superior in light resistance and exhibit a higher intensity of fluorescing by use of a fluorescent pigment than that of fluorescent particles using a fluorescent dyestuff, there is the problem that the production thereof necessitates expensive apparatus, and the production yield is low.
On the other hand, inclusion of the fluorescent pigment itself in paper causes many problems. First, there is the problem that since the particle diameter of a commercial fluorescent pigment is as small as about 0.5 to 3 &mgr;m, the presence of individual particles cannot be recognized even if paper containing a few % of fluorescent pigment particles is irradiated with ultraviolet rays in a bright room. To be able to recognize the presence of the fluorescent pigment, the particle size should be increased, but in this case, the pigment with a special particle size should be produced, and thus the price of the usually expensive fluorescent pigment is further raised. In addition, since the specific gravity of the inorganic fluorescent pigment is as high as 4 to 5, there arises the problem that, if paper making is conducted using a pulp slurry containing the pigment with a large particle diameter, the fluorescent pigment is precipitated in the slurry during transfer thereof.
DISCLOSURE OF THE INVENTION
This invention was made under these circumstances, and the object of this invention is to provide completely novel fluorescent particles and a process for producing the same, as well as anti-falsification paper prepared by inclusion of the fluorescent particles in the paper so that the particles fluorescing in various hues with unique cylindrical or spherical shapes can be clearly visually recognized upon irradiation with ultraviolet rays and are further excellent in light resistance.
The fluorescent particles according to the present invention comprise granules of a mixture of a water-insoluble dyestuff and/or pigment fluorescing upon irradiation with ultraviolet rays (also referred to hereinafter as “fluorescent dyestuff” and “fluorescent pigment” or as “fluorescent agent” when the two are generally named) and a powdery material; and the fluorescent particles can be produced by mixing the fluorescent dyestuff and/or the fluorescent pigment with the powdery material and then granulating the mixture.
Further, the fluorescent particles of the present invention comprise granules of a powdery material and a coating layer of a fluorescent dyestuff and/or a fluorescent pigment formed on the surface of the granules; and the fluorescent particles can be produced by granulating the powdery material and then coating the surface of the granules with the fluorescent dyestuff and/or the fluorescent pigment.
Further, the fluorescent particles of the present invention comprise granules of a mixture of a fluorescent dyestuff and/or a fluorescent pigment, a powdery material and a white pigment; and the fluorescent particles can be produced by mixing the fluorescent dyestuff and/or the fluorescent pigment, the powdery material and the white pigment and then granulating this mixture.
Further, the fluorescent particles of the present invention comprise granules of a mixture of a powdery material and a white pigment and a coating layer of a fluorescent dyestuff and/or a fluorescent pigment formed on the surface of the granules; and the fluorescent particles can be produced by granulating a mixture of the powdery material and the white pigment and then coating the surface of the granules with the fluorescent dyestuff and/or the fluorescent pigment.
Further, the fluorescent particles of the present invention comprise granules of a powdery material, a coating layer of a white pigment formed on the surface of the granules and a coating layer of a fluorescent dyestuff and/or a fluorescent pigment formed in the outside of the coating layer of the white pigment; and the fluorescent particles can be produced by granulating the powdery material, then coating the surface of the granules with the white pigment, and coating the outside of the coating layer of the white pigment with the fluorescent dyestuff and/or the fluorescent pigment.
In the present invention, a resin binder having 2 or more reactive groups reacting with the hydroxyl groups of the powdery material may be used in granulation or coating, whereby water-resistant fluorescent particles can be produced.
That is, the water-resistant fluorescent particles of the present invention comprise granules of a mixture of a powdery material having hydroxyl groups, a fluorescent dyestuff and/or a fluorescent pigment, and a resin binder having 2 or more reactive groups (hereinafter referred to simply as resin binder) reacting with the hydroxyl groups of the powdery material; and the fluorescent particles can be produced by mixing the powdery material, the fluorescent dyestuff and/or the fluorescent pigment and the resin binder and then granulating the mixture.
Further, the water-resistant fluorescent particles of the present invention comprise granules of a mixture of a powdery
Asai Yasuhiko
Murakami Toru
Nakajima Tohru
Watanabe Yoshihiro
Kiliman Leszek
Tokushu Paper Mfg. Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Fluorescent particles, method for preparing the same and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fluorescent particles, method for preparing the same and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fluorescent particles, method for preparing the same and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3170500