Technical field

The present invention relates to a method of marking objects to be identified, especially vehicles, by a hidden mark becoming visible in ultra-violet light (UV light) .

Background of the invention

Patent specification HU-PS 212 215 describes a method of marking outer surfaces of vehicles or other objects by a hidden mark becoming visible in ultra-violet light. With this known solution, appropriate marks (e.g. letters and/or numerals) of a very thin layer of a UV sensitive paint will be produced on the surface to be marked. Thereafter the marked surface will be covered by a protective lacquering. This method needs substantial technical means. Certain steps can be realized in car body spraying workshops and drying rooms, respectively. After applying of the marks lacquering of the marked surface has to be performed in a fully closed dust-free room securing appropriate protection thereof. Consequently, applying of the marks means considerable costs. Further, m the case of new cars one may lose the guaranty because of processing on the original lacquering.

Object of the present invention is to eliminate the above deficiencies of the known method.

Therefore, the present invention aims at creating a method of marking objects to be identified, especially vehicles, by a hidden mark becoming visible in ultra-violet light which method is much more simple, less expensive and does

not mean danger as to guaranty rights of owners of new cars .

The present invention is based on the idea that applying as UV sensitive substance a sprayable paint which is able to diffuse into the surface to be marked e.g. into the anti- corrosion or decorative polishing layer of a vehicle cover plate will result in much more simple marking procedure. Moreover, the marked surface remains undamaged and a very durable marking will be obtained.

Summary of the invention

The object set forth above is accomplished by a method of marking objects to be identified, especially vehicles, by a hidden mark becoming visible in ultra-violet light, in which method identifying marks, especially numerals and/or letters are applied, preferably by using patterns, to the surface to be marked by a paint comprising pigments hidden in natural light but becoming visible in ultra-violet light; wherein, according to the present invention, applying of identifying marks is performed by using a paint being able to diffuse into the material of the surface to be marked, then the said surface is let rest for a periode sufficient for diffusion of said paint, and thereafter, optionally, final surface handling, especially polishing is performed.

Preferably, the surface to be marked is preheated to a temperature between 60 and 80 °C prior to applying the said paint.

The said preheating is accomplished preferably by means of an infra-red lamp.

The surface to be marked is preferably degreased.

Preferably, the paint is applied by means of spraying and/or mk ettmg.

In a preferred embodiment, the paint is applied in up to three or four layers with a total thickness of 5 to 10 μ. Detailed description of the preferred embodiment

A surface of an automotive vehicle to be marked is made free of silicone by wiping it twice using fresh towels wetted with a silicone removing liquid detergent then roughed (unpolished) by means of an ultra-fine sponge (e.g. 3M Scotch Bπte ultra fine) . The cleaned surface is heated to a temperature between 60 and 80 °C by means of infra-red lamps. The master pattern (negative) of the mark to be applied (e.g. registration number) is fixed with adhesive ribbon or magnet to the heated surface. The pattern may be made by plotter or magnet cut out. In the case of less sensitive surfaces (e.g. car upholster) common letter patterns may be used as well.

A paint which is hidden in natural light but become visible in ultra-violet light is applied to mark the surface. The paint is applied using a dye sprayer (or mk et printer) . Base of the paint can be Standox 2K-Loeser Scharf 11031 produced by Herberts STANDOX Autolack (Germany) . An UV sensitive pigment is added to this paint by SERVIND Budapest Kft. (Hungary) in order to obtain the substance to be sprayed onto the surface which has to be marked. This paint comprises two components, A and B to be mixed in volume ratio of 1:1. After mixing the paint is ready to spraying, dilution is not needed.

Preferred parameters of spraying are as follows:

Dye sprayer: SATA Dekor Z or SATA Mini Jet

Nozzle size: 0,5 to 0,8 mm

Spraying pressure: 1,0 to 1,5 bar

Number of layers: 3 to 4

Total thickness: at least 5 to 10 μ (too thick layers could become visible)

After ventilation of 15 to 20 minutes the master pattern is removed. According to our experiences negative master patterns are more convenient than positives. The paint used for marking will diffuse (penetrate) at normal temperature (20 °C) as far as the metal layer of the car-body plate in four days. Thereafter, final fine polishing of the marked surface is accomplished. (If needed, the car may be used during the said four days.) After four days the marking can not be removed by means of common detergents. In the case of merked textil surfaces further treatment is not needed, they can be cleaned after four days without damaging of the marks.

The sprayed and/or inkjetted paint makes the surface to be marked temporarily soft. Thus the UV sensitive pigment will diffuse into the treated surface. The diffusion is improved if the surface is heated for further 10 to 15 minutes by means of the infra-red lamps. Under the influence of the infra-red radiation inner layers will warm up first. Thus diffusion action will be effective even through several layers of paint and the UV sensitive pigment will deeply penetrate the polished surface of the vehicle. The UV sensitive pigment can be introduced the same way into plastic and textile surfaces.

The painted marks made according to the present invention remain recognisable in UV light even after fourfold re- polishing of the car.

The paint can be applied even subsequently onto any accessible surface without damaging it. Any suitable surface of a car can be marked e.g. polished parts, inner upholstered parts, carpets, wall coverings, plastic parts etc. In the case of outer surfaces lower parts of the car

body are to be preferred since marks used on upper parts eventually may become visible in very strong sunshine.

Main advantages of the present invention are as follows:

- no drying room is needed;

- lacquering of the surface becomes superfluous;

- semi-skilled workers can carry out the full procedure; danger of loss of guaranty is minimized since the original surface will be restored practically to the full.

SUBSTITUTESHEET(RULE26.