Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2000-09-18
2002-12-24
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031680, C106S031700
Reexamination Certificate
active
06497759
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a novel scratch ink composition and a writing utensil utilizing the composition.
BACKGROUND OF THE INVENTION
The scratch ink is a kind of ink adapted to form an opaque film capable of hiding the character, numeral, symbol and/or other pattern image on a substrate for use in the field of lottery and game tickets or the like and removable by scratching with a coin edge, a fingernail or a rubber eraser.
With regard to the printed matter embodying such a function, there is known the artifact produced by forming a desired image, such as a drawing, characters, figures or a photograph, by printing on the surface of a substrate, such as a paper or plastic sheet, applying a wax-formulated solution of a medium composed of a resin, a vegetable oil, a petroleum-based solvent and a desiccant over the image area to form a medium layer, and forming an opaque image (layer) capable of hiding the first-mentioned image by printing over said medium layer either locally or all over so that when the surface of the artifact is abraded or scratched the printing ink forming said opaque image is dislodged to reveal the underlying printed image (Japanese Examined Utility Model Publication S44-12094).
However, to produce such a printed matter, it is necessary to form a medium layer on the printed character, figure or the like image in the first place and then form an opaque layer, so that the method can hardly be said to be expedient. Particularly because it is intended for the production of printed matter, the method is unsuited for gimmicks to be enjoyed personally or at the family level.
There also is known an ink composition compatible with paper such that the characters or pattern written on a paper substrate can be erased with a rubber eraser or the like characterized by its comprising a uniform pigment dispersion prepared by dispersing a pigment selected from the group consisting of carbon black and aniline black in an aqueous medium containing a high molecular polyethylene oxide, optionally with the aid of a surfactant, and containing 1~20 weight % of said pigment and 0.01~5 weight % of said high molecular polyethylene oxide (Japanese Examined Patent Publication H1-39470).
However, the film formed from this ink composition is hardly removable with a rubber eraser or the like at times and the composition remains to be further improved in erasability.
There also is available an erasable ink characterized by its comprising a resin having a film-forming temperature of not higher than 0° C. or a glass transition temperature of not higher than 0° C., a colored powder consisting of fine spherical particles ranging from 1 to 20&mgr; in diameter, and water and having an ink viscosity of 5~35 mPa·sec (Japanese Unexamined Patent Publication H5-279614).
Though this ink is erasable, it inherently has no covering power so that characters or other patterns cannot be hidden. Therefore, the ink cannot be used as a scratch ink which is intrinsically expected to hide character, pattern or other images. On the other hand, if an attempt is made to impart a covering power to this ink, chances are that its erasability will be sacrificed.
Thus, these known inks are invariably deficient in one or more of the performance quality parameters of erasability, hiding power and ease of use, and up to the present there has not been available an ink satisfying all the requirements, that is to say an ink suited for erasable applications.
An object of the present invention is to provide a scratch ink composition improved in erasability, hiding power and ease of use.
SUMMARY OF THE INVENTION
After an intensive research to overcome the above disadvantages of the prior art, the present inventor found that an ink composition having the herein-defined composition accomplishes the above object and has accordingly developed the present invention.
The present invention, therefore, is directed to the following scratch ink compositions and a writing utensil which utilizes the same.
1. A scratch ink composition comprising a flaky pigment, a resin component and a solvent, the particles of the pigment having a particle size distribution (as determined with a laser diffraction particle size analyzer) such that the integral fraction of particles not larger than 10 &mgr;m in diameter is not more than 30%.
2. A scratch ink composition as defined in the above paragraph 1 wherein the particles constituting an integral fraction of 30% in particle size distribution (as determined with a laser diffraction particle size analyzer) are 3~200 &mgr;m in diameter and that its thickness is {fraction (1/40)}~{fraction (1/60)} of the particle diameter.
3. A writing utensil comprising the composition defined in the above paragraph 1 or 2 as its ink component.
4. A scratch material comprising a film formed from the composition defined in the above paragraph 1 or 2 on a substrate carrying a character or pattern image, said film hiding said character or pattern image.
5. A method of producing a scratch material which comprises printing a substrate with a character or pattern image and then applying the composition defined in the above paragraph 1 or 2 in superimposition to hide said character or pattern image.
DETAILED DESCRIPTION OF THE INVENTION
1. Scratch Ink Composition
Referring, first, to the flaky pigment for use in the composition of the present invention, its particle size distribution (as determined with a laser diffraction particle size analyzer) should be such that the integral fraction of particles not larger than 10 &mgr;m is not more than 30% (preferably not more than 20%). Inasmuch as this condition is satisfied, any commercial pigment can be used as it is.
Even the pigment which fails to satisfy the above condition can be used as the pigment in the present invention by eliminating or reducing the proportion of particles not larger than 10 &mgr;m by the known fractionation technique such as centrifugation, filtration or addition of a flocculant or, where necessary, adding particles over 10 &mgr;m in diameter.
The particle morphology of the flaky pigment is not particularly restricted inasmuch as the desired hiding power can be attained but may usually be such that the particle diameter (referred to also as D
30
) corresponding to an integral fraction of 30% (D
30
) in particle size distribution (as determined with a laser diffraction particle size distribution analyzer) is about 3~200 &mgr;m, preferably 15~50 &mgr;m. Moreover, the thickness of the flaky pigment may be {fraction (1/40)}~{fraction (1/60)}, preferably about {fraction (1/50)}, of the D
30
value.
The flaky pigment (raw material) is not restricted inasmuch as it provides the desired hiding power and may be an organic pigment or an inorganic pigment (inclusive of a metal powder pigment). For example, an aluminum powder pigment or a metal-coated inorganic pigment (e.g. the pigment obtained by covering glass flakes with a metallic film by a suitable coating technique such as electroless plating or sputtering; the pigment obtained by covering an inorganic or metallic material, e.g. mica or aluminum, with a metallic film by a suitable coating technique; etc.) can be mentioned. These pigments can be used independently or in a suitable combination.
As the flaky pigment, commercial products can also be used. To mention a few examples, the aluminum powder pigment includes “Alpaste WXM-U75C”, “Alpaste WXM5422” and “Alpaste WXM1440” (all from Toyo Aluminum Co.); the pigment obtained by covering glass flakes with a metallic film by electroless plating (metal-coated inorganic pigment) includes “Metashine REFSX-2015PS”, “Metashine REFSX-2025P” and “Metashine REFSX-2040PS” (all from Toyo Aluminum Co.); and the pigment obtained by covering glass flakes with a metallic film by sputtering (metal-coated inorganic pigment) includes “Crystal Color GF2125”, “Crystal Color GF2525”, “Crystal Color GF2140” and “Crystal Color GF2125” (all from Toyo Aluminum Co.).
The proportion of flaky pigment (on a solid basis) can be judiciously selected according to its
Murata Naoshi
Yamamoto Yuki
Yoshimura Yasuyuki
Esq. Gloria Tsui-Yip
Klemanski Helene
Miskin, Esq. Howard C.
Sakura Color Products Corp.
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