FR2570384A1 - Process for forming images using ultraviolet radiation - Google Patents

Abstract

The object which is to be made fluorescent is coated with a polymer solution including a proportion of 3 to 10 % of a fluorescent body. Applications: entertainment shows, advertising, jewellery, toys and the like.

Description

ULTRAVIOLET IRRADIATION IMAGE FORMATION PROCESS
The subject of the present invention is a method of forming images by irradiation with an ultraviolet source intended in particular, but not exclusively, for obtaining new aesthetic effects.

We know that objects do not have their own color and that the apparent color of an object results from the reflection of part of the spectrum of the irradiation source, the other part of the spectrum being absorbed by the object. .

We also know of bodies which have the property of being fluorescent or luminescent, that is to say of transforming received radiation into radiation of longer wavelength and in particular of giving, by irradiation by a source. emitting visible light outside the visible spectrum. Are known, in particular bodies which, by W irradiation, that is to say by a source emitting in a spectrum whose frequencies are lower than 0.4 microns (such as a WOOD lamp, making it possible to select radiations in the near ultraviolet, thanks to a black nickel oxide filter, for example) constitute a visible secondary source. When the photons of the radiation strike the atoms of a fluorescent substance, there is absorption of the energy supplied and transformation thereof which is re-emitted with a lower frequency, that is to say with a wavelength greater than that of the incident radiation. In particular, the so-called fluorescent paints visible both in daylight and in "black" light, resulting from a mixture of fluorescent pigments and a binder constitute, by irradiation W a secondary source. But both in visible light and in Wood light, these paintings, the colors of which are limited to four or five, are aggressive and difficult to bear with the eye. They are also opaque, brittle and deteriorate by friction.

The object of the present invention is to develop 5 applications of fluorescent bodies - by overcoming the disadvantages of known bodies and by making it possible to obtain practically any shade of color in light of
Wood.

According to the present invention, the method of forming images by ultraviolet irradiation is characterized in that it consists in coating an object, a part of an object or a set of objects with a transparent support in which a solution is introduced. of a fluorescent body in a proportion at most equal to 10% by weight of the support.

It is thus possible to obtain the fluorescence of tints or body colors which are not naturally fluorescent either by reflection if the source W is arranged above the object, or by transmission if the object being itself transparent the UV source is arranged behind the object relative to the observer. The invention makes it possible to identify a much wider colorimetric range than the existing one and, possibly, to enhance already existing fluorescent colors, and currently eighteen shades are available instead of only five in the prior art.

The colors thus obtained show good resistance to light, mechanical resistance to friction, and to a pressure equivalent to 5000 bands, as well as chemical resistance to acids.

According to another characteristic of the invention, the transparent support consists of a vinyl or acrylic polymer soluble in water. The support + solution assembly can thus be extended to any surface or used in the liquid state. The fluorescent bodies used in solution can be, for example: fluorescein or autunite for greens, esculin for blues, fluorite for mauves, auramine for yellows, rhodamine for roses, etc. .. Other transparent polyymers can also be used.

Other characteristics and advantages of the present invention will become apparent during the description which follows of particular embodiments, given solely by way of nonlimiting examples.

To obtain the desired effect, it is possible either to use an existing image, for example formed from conventional paints or inks and to cover this image with a polymer-fluorescent or luminescent compound mixture in solution, or to produce the image using using a mixture of conventional colored pigments, a polymer and fluorescent pigments. This result essentially results from the transparency effect created by the polymer layer which can be adjusted in thickness and from the fluorescence depending in part on the concentration of the solution in fluorescent pigments. The transparency of the support makes it possible to use only a small proportion of fluorescent pigments. For example, if one extends a layer of mixture on a canvas painted in oil, this canvas irradiated by -a UV source gives an image very luminescent.

The mixture is, for example, constituted by a polymethyl acrylate into which a plasticizer composed of an acrylic monomer in emulsion at 50% in water is introduced. The pigment consists, for example, of fluorescein diluted between 2 and 10% in water. - It can also consist of a polymethylacrylate with 3 or 4% ammonium, an acrylic acid neutralized at 1 ammonia being added in a suitable proportion in the polymer.

The fluorescent solution is then added to the polymer before application to the object to be covered.

The mixtures obtained as just exposed are deposited on an already painted support such as an oil paint on canvas.

EXAMPLE: it is proposed to make a wind musical instrument fluorescent for a Wood light show, the application being made by a series of successive layers whose thickness is approximately 1/10 mm. Apply successively to the body of the instrument: a white acrylic-based paint which dries immediately; - a highly diluted blue acrylic paint in three coats also; - a liquid solution comprising an ethyl metacrylate with an acrylic monomer to which has been added a properly diluted solution of low dose fluorescein in three layers; - a commercial fluorescent blue paint transformed by the addition of ethyl acetyl acetate ion periodate plus ammonium acetate; -a transparent polymer varnish in three layers to obtain additional protection.

The keying of the instrument received: - two layers of black color, glycerophthalic base; - a mixture of fluorescent blue and orange giving daylight a brown, almost anthracite shade and, under the excitement of a Wood lamp, a salmon pink coloring; - To give mechanical resistance and a very smooth appearance to the touch, two layers of polymer gel were applied to which was added, by dilution, an acrylic acid neutralized with ammonia. This application is carried out with a very fine brush.

 To obtain white in UV light, we proceed as follows: we mix a blue paint and a yellow paint so as to obtain a pale green in sunlight.

U.V. irradiation gives a brilliant white.

The applications of the invention are extremely diverse since the fluorescent solution can be applied to any support or material such as: artistic works, decorations, stage props and costumes, jewelry, advertising works, video films, toys, etc.

The present invention also finds purely industrial applications, for example for the protection of information carried on security documents.

These, after printing, are covered with a fluorescent layer according to the invention. The dilution of the fluorescent body is around 3%. Any attempt at falsification immediately appears in Wood's light since it necessarily results in a scraping of the layer to access the support. The falsifier cannot find the exact composition of the protective layer.

 The present invention can be implemented both by reflection and by transmission, which makes it possible to obtain new effects.

The applications which have been indicated above are understood in the case where the polymer is associated with a plasticizer which ensures its very rapid drying. The invention also finds n 4> 5 tee in the field of fluorescent fluids. To this end, transparent tubes are filled with fluids carrying fluorescent pigments, the mobility of the fluids being ensured for example by suction and pressure pumps.

It goes without saying that many variants can be introduced, in particular by substitution of technically equivalent means without thereby departing from the scope of the invention.

Claims (5)

10 Method of forming images by irradiation  ultraviolet, characterized in that it consists in coating  an object, part of an object or a set of objects with  a transparent support into which a  solution of a fluorescent body in a proportion to the  more equal to 10% by weight of the support, then to be irradiated  the object.  20 Method according to claim 1, characterized in that the  support consists of a vinyl polymer or  acrylic and in particular a polymethyl acrylate. Process according to claim 2, characterized in that  a polymethylacetacrylate gel including 3 to  4% ammonium acrylate into which a  solution of acrylic acid neutralized with ammonia and a  fluorescent body. 40 A method according to any one of claims  previous, characterized in that the body or bodies  fluorescent lamps are chosen from the class comprising:  fluorescein, autunite for greens, esculin for  bruises, fluorite, auramine, rhodamine. 50 Products obtained by applying a solution according to  one of the preceding claims.