DE19517625A1 - Laser printing esp. on glass or plastic substrate - Google Patents

Abstract

Patterned laser printing on a solid substrate surface using pigments involves (a) contacting the substrate surface with a layer contg. one or more pigments; (b) laser irradiating the layer according to the pattern to be printed, the laser beam reaching the substrate surface/layer interface with sufficient energy to deposit the pigments or their decomposition on the substrate surface; and (c) removing the layer from the substrate surface. Pref. the pigment-contg, layer is a pigment-contg, plastic foil, a pigment powder layer, a foil consisting entirely of pigment material or a pigmented lacquer layer.

Description

The invention relates to a method for pattern-like printing of solid substrate surfaces using a laser beam and using at least one pigment.

The surfaces of solid substrates, such as objects made of glass, plastic, porcelain or ceramics, are often printed for a wide variety of purposes. This printing may be used for decorative purposes, for labeling purposes or for advertising purposes, d. H. from pure optical reasons or serve a technical purpose, such as for surface protection, for the production of conductive or reflective coatings. The The invention is not intended to be limited to a specific purpose of printing.

The printing of glass and plastic objects using color pastes or is known Paints that contain dyes or pigments in a binder system. Such Imprints are against solvents and strong acids and alkalis, which the Destroy printing sooner or later, relatively unstable. Even with exposure Common detergent over long periods of time will change the appearance of such prints impaired, so that they can not be called dishwasher safe.  

In addition, printing with such color pastes is complex and widely used Solvents, which can create a permanent working atmosphere. Color residues of such printing processes are difficult to dispose of, especially if the Printing machines need to be cleaned.

Another common method is to etch glass surfaces with hydrofluoric acid. This is a procedure that is questionable due to the safety aspects, since hydrofluoric acid is found in the smallest Concentrations can cause skin and eye burns. Here, too, occur considerable Disposal problems.

For labeling plastic objects or foils, it is known to use a pigment, like carbon, to incorporate in an even distribution and the surface of the so to irradiate pigmented plastic object in a pattern with a laser, thereby the inscription appears lighter in the irradiated areas. Such procedures are in "Kunststoffe 83", page 11 (1993) and in European patents 0 190 997, 0 522 370 and 0 330 869. This method cannot be used for glass, porcelain and Ceramic objects, but only apply to plastic objects, and it has the considerable disadvantage that the incorporation of pigments, especially in the case of metal-containing pigments, the properties of the plastic are deteriorated.

The object underlying the invention was therefore to develop a method for pattern printing of solid substrate surfaces, such as glass and Plastic, which has the disadvantages of the prior art described above eliminated and in particular leads to permanent printing without the substrate in all of its substances must be incorporated that impair its properties.

This object is achieved by the inventive method for pattern printing solid substrate surfaces using a laser beam and using at least solved a pigment, which is characterized in that one at least one Brings the pigment-containing layer into contact with the substrate surface to be printed, irradiated this layer in the form of the pattern to be printed with a laser such that the Laser beam the interface between the substrate surface and the layer with sufficient Energy reaches the pigment or a degradation product of the same on the substrate surface to transfer, and then the layer removed from the substrate surface.

If we are talking about a pattern-like printing or a pattern, this should be  Label have the broadest possible meaning and all letters, numbers and others Characters, ornaments, decorations and the like.

It is surprising that with the method according to the invention a clean printing of the Substrate surfaces is achieved without the layer of a substrate surface entirely or partially sticks or smeared the printed patterns. The prints are partially acid, alkali and washable and can be used without caustic substances or Solvent must be used.

The pigment-containing layer can contain a pigment-containing film, such as a plastic film evenly distributed fine-particle pigment, a pigment powder layer, a pigment film, which consists entirely of the pigment, or a pigment varnish, which is the finely divided pigment contained in a binder. The layer in the form of a is particularly advantageous pigment-containing film, as this is easily applied to curved substrate surfaces and can be removed from the surfaces on the printing. One from the Pigment material consisting of pigment material is and is particularly suitable for metal foils for example an aluminum foil. Pigment coatings are applied in the usual way printed surface and chemically or physically on the surface dried. After printing, these pigmented varnishes must be removed so that the The binders of these pigment lacquers must be soluble and remain soluble during laser irradiation have to. It is advisable to use water-soluble binders so that none when dissolved need to use organic solvents.

Carbon, metal compounds and metals come into consideration as pigments. At The use of metal compounds decompose them during the radiation process Formation of metal or metal oxide or another degradation product of the metal compound, which are transferred to the surface of the substrate. In this context, none Specific theory, but it is currently believed that The use of metal compounds, as a rule, creates and transmits elementary metal becomes. One can thus, for example, print using the method according to the invention Apply circuitry to glass surfaces or other substrate surfaces or such surfaces provided with electrically conductive or thermally conductive printing for other purposes. It is also surprising that the prints adhere very firmly to the substrate surface probably diffuse into the substrate surface during the printing process and itself are resistant to strong acids and bases. In particular, are suitable for the inventive method heavy metal compounds including noble metal compounds,  like gold phosphate and silver phosphate. The use of an aluminum foil leads to a Printing in the form of an etching-like haze, while carbon and the Heavy metals lead to dark-colored, such as black, reddish or brownish, patterns. With the aid of a few series tests, the average specialist can use the here made description of the inventive method are selected, which Pigments are suitable and respond to certain available lasers.

Depending on the type of substrate used, the laser radiation can pass through the substrate through or from the coating side. With a transparent substrate, such as a glass object, it is expedient to pass the laser radiation through the glass to make. The same applies to translucent plastic objects. In other cases, especially if the object to be printed is not sufficiently translucent it may be expedient to carry out the laser radiation from the side of the coating. In this case, however, the pigment-containing layer must be thin enough to use the laser sufficient energy up to the interface between the substrate surface and the let through the pigment-containing layer.

The method according to the invention is not intended to use special types of lasers be limited. All common laser types, such as Nd-YAG lasers, excimer Lasers, nitrogen lasers, CO and CO₂ lasers and other known gas lasers. It is expedient to use lasers that emit light with a wavelength of 100 nm to 20 µm, preferably emit from 150 to 1200 nm. Frequency doubled are particularly preferred Nd-YAG laser with a wavelength of approximately 532 nm.

The method according to the invention can be used for printing any solid substrate surfaces are used, with smooth substrate surfaces being particularly useful. As For example, substrates come from objects made of glass, porcelain, ceramic, stone, plastic or other materials that do not carbonize when exposed to laser beams. The method is particularly suitable for printing on glass and plastic, in particular of glass, where so far no process with comparable effect is available and the Properties of the printing are particularly surprising.

In addition to applying markings and decorative elements, this is also suitable Method according to the invention, as mentioned, in particular for printing with electrically conductive tracks, which makes complex galvanic processes unnecessary. Also galvanically applied conductor tracks can be reinforced using this method.  

On the other hand, reflective prints or surface protection prints be applied.

The following examples serve to further explain the invention.

example 1

TiO₂ powder was in a uniform smooth layer under a thickness of about 1 mm Distributed glass plate (window glass). With the help of an Nd-YAG laser with a wavelength of 1064 nm and a writing speed of 50 mm / s was a labeling beam through the Point the glass through the powder. The black writing on the glass plate was resistant to concentrated hydrochloric acid and sodium hydroxide solution as well as ethanol.

Example 2

A commercially available soot-containing film was placed under a glass plate with a thickness of 2 mm placed. Using an Nd-YAG laser with a wavelength of 1064 nm and one Writing speed of 50 mm / s was a label beam through the glass aimed at the slide. A was created on the glass plate in accordance with the laser beam guidance black writing, in concentrated hydrochloric acid and sodium hydroxide solution and against alcohol was constant.

Example 3

A polyurethane plate containing 1% copper hydroxide phosphate was placed under a 1 mm strong glass plate. As in Examples 1 and 2, was passed through the glass plate the laser beam is aimed at the pigmented polyurethane plate. The resulting red-brown Writing was acid-soluble but alcohol-resistant.

Example 4

An anodized aluminum plate with a black surface was placed under a 1 mm thick Glass plate placed. The label beam was through as in the previous examples the glass directed towards the aluminum plate, with a white, etching-like writing originated.  

Example 5

An approximately 0.1 mm thick layer of powder of silver phosphate was placed on a porcelain plate equally distributed. With the help of an Nd-YAG laser with a wavelength of 1064 nm and a writing speed of 50 mm / s as in the previous examples this time the laser beam is directed from the coating side onto the powder. To Removal of the powder from the surface of the porcelain plate showed a reddish writing.

Example 6

A 1 mm thick layer of silver phosphate was applied to a uniformly thick layer of powder transparent polyurethane plate. Using the in the previous examples called laser was a labeling beam with a wavelength of 1064 nm Writing speed of 50 mm / s through the polyurethane plate onto the Layer of powder directed. A shiny metallic pattern was created on the polyurethane plate.

Example 7

On an even, even layer of trituration of gold chloride with tricalcium phosphate a 1 mm thick glass plate was placed. The irradiation was carried out as in Example 1 by the Glass plate through to the powder layer. There was a red-brown against hydrochloric acid permanent lettering on the glass plate.

Claims (8)

1. A method for pattern-like printing of solid substrate surfaces with the aid of a laser beam and using at least one pigment, characterized in that a layer containing the at least one pigment is brought into contact with the substrate surface to be printed, this layer in the form of the pattern to be printed irradiated with a laser such that the laser beam reaches the interface between the substrate surface and the layer with sufficient energy to transfer the pigment or a degradation product thereof to the substrate surface, and then removes the pigment-containing layer from the substrate surface. 2. The method according to claim 1, characterized in that the pigment is carbon material, a metal compound or an elementary metal used. 3. The method according to claim 2, characterized in that one as a pigment Heavy metal compound used. 4. The method according to any one of claims 1 to 3, characterized in that as Layer containing pigment is a pigment-containing plastic film, a pigment powder layer, a film consisting entirely of the pigment material or a Pigment lacquer layer used. 5. The method according to any one of claims 1 to 4, characterized in that the Layer containing pigment irradiated through the substrate. 6. The method according to any one of claims 1 to 5, characterized in that one Laser used, the light of a wavelength of 100 nm to 20 microns, preferably from 150 to 1200 nm emitted. 7. The method according to any one of claims 1 to 6, characterized in that one Nd-YAG laser, an excimer laser, a nitrogen laser or a CO or CO₂- Laser used.   8. The method according to any one of claims 1 to 7, characterized in that as Substrate uses a glass or plastic object.