WO1991008117A1 - Process for applying pictorial designs to the surfaces of articles - Google Patents

Abstract

For the production of transfer designs, the invention uses a printing device which applies various designs, such as bar codes, directly to a sheet of transfer paper, design selection being electronically controlled and for instance computer-programmed. The design is then transferred, by a transfer peeling process, to the surface of an article, on which it is fixed permanently by heating. The special paper and printing ink used in the process must therefore be heat-resistant at the temperatures used in the particular application. This also applies to the varnish coating applied to the special paper after the design has been printed.

Description

 Process for applying images to objects

The invention relates to a method for applying pictorial representations such as e.g. Decorations or barcodes in the transfer process on objects, which are then subjected to a processing process in a higher temperature range.

Such pictorial representations are also generally referred to as transfer decorations because they are transferred from a printing medium by means of a pull-off process to the object to be provided with the pictorial representation and are applied thereon in a permanent form. The term pictorial representations or images are understood to mean illustrations and decorative motifs as well as figurative and word marks, signs, logos, operating instructions, numbers, bar codes or combinations of the aforementioned types.

If, after the so-called transfer decoration has been applied, objects go through a further processing process at a higher temperature, this involves, for example, a heat treatment of approximately 400 ° C. Glass components or of almost 1300 ° C for sanitary ware products, which are fired, depending on the product, these objects are only subjected to heat treatment for a few minutes to several hours or even for several days. Glass components are understood to mean, for example, picture tubes for television sets or office equipment, and also glass casting molds for spectacle lenses, in which temperatures of up to 500 ° C. are used as well as for drinking and laboratory glasses, in which even higher temperatures up to around 700 C are used. In the case of porcelain and ceramic goods such as sanitary ware, depending on the article, temperatures of 700 ° C. to almost 1300 ° C. are used during the firing.

The production of transfer decorations has hitherto been a relatively complex process, in which a representative template must first be produced following the design and a photographic reprofilm is then produced, with the aid of which a printing form such as a stencil is then used is produced for screen printing or a plate for offset printing. Finally, a printing machine must be set up in order to print on a special paper by means of screen or offset printing. This special paper is a printing medium with a water-soluble separating layer, also referred to as "decal paper". Printing inks based on glass pigments are generally used, the melting point of which is matched to the temperature range of the planned heat application. Then a so-called "overprint varnish" is applied, which is colorless or varnished, which is referred to as "over-filming". Subsequently, the printing ink and the surface of the object to be provided with the transfer decor are then firmly bonded by sintering when the intended temperature of the heat application has been reached.

This conventional method is relatively complex and too expensive if only a few copies of the individual transfer decor are required or if each individual is to differ from the other, which is particularly the case when transfer decorations in the form of continuous ¬ fend numbered barcodes to be produced. As a rule, only a single copy is to be produced for each number, which is only a purely functional task Has .

The present invention was therefore based on the object, instead of the previously conventional way of using a reprofile template and a reprofilm and a printing form, to develop a much more economical and quicker method leading to the result, in particular for unequal transfer decorations such as continuously barcodes.

The method according to claim 1 serves to achieve this object. In a preferred manner, the desired transfer decor, such as, for example, a consecutively numbered bar code, is produced as software by means of an EDP program, and this program is used to control the printing device, which transfers -Decor applied directly to the water-soluble separating layer of a special paper for ceramic printing. As special paper or decal paper, a material is preferably used which is matched to this method and in particular to the heat during the fixing of the printing ink in the stoving station of the printing device. As a printing device, xerographic laser printers as well as ion deposit printers and magnetographic printers as well as thermal transfer printers and similar computer-controlled devices can be used. In this case, the toner used in the respective printer for the usual office use, ie the mostly powdery color, must be replaced or supplemented with toner which contains the color pigments suitable for high temperatures and adapted to the heat effect used. These can either simply be added to the toner or added in the form of resin-coated pigments. In the case of a thermal transfer printer, these measures relate to the color of the ink ribbon, in the coloring of which the special alpi gmente have to be processed. The prints made directly on the special paper are then "over-filmed" using an overprint varnish. An overprint varnish is used which is suitable for the respective printing method, in particular for the effects of the printing method, such as the change in the water-soluble separating layer of the decal paper due to the action of heat when passing through the fixing station in the printer.

When applying the overprint varnish, a so-called grid pattern can also be used, with the result that any air and water inclusions that are present can escape through small holes in the varnish layer when the decal is applied and when the decal is baked, so that the transfer decor produced does not get through explosive expansion of such inclusions is destroyed under the influence of heat.

Claims

Patent claims 1.Method for applying visual representations such as e.g. Transfer decorations or bar codes in the transfer process to objects which are subsequently subjected to a processing process in a higher temperature range, characterized in that the pictorial representation to be transmitted is created by means of an electronically controllable and optionally programmable printing device and directly by the printing device applied to a paper carrier and then transferred to the object in the peeling process, the paper carrier and the printing ink being selected such that they are heat-resistant in the temperature range provided in each case during the subsequent processing process. 2. The method according to claim 1, characterized in that decal paper with resistance to heat is used as the paper carrier during the fixing of the printing ink in the stoving station of the printing device. 3. The method according to claim 1, characterized gekenn¬ characterized in that the printer xerografi see laser printer, ion deposit printer, magnetographic printer or thermal transfer printer are used. 4. The method according to claim 1, characterized gekenn¬ characterized in that the visual representation created by means of an EDP program and this program is used to control the printing device, which is the pictorial Application directly onto the paper carrier.