DE102008034906A1 - Screen printing form for graphic applications and method for producing a screen printing form - Google Patents

Abstract

In a screen printing form (10, 20, 40, 60) for graphic applications with a perforated film (11, 50, 61), the film (11, 50, 61) exclusively in a printing area (13, 28, 41, 62) by means of perforated by a laser.

Description

The The invention relates to a screen printing form for graphic applications with a perforated film and a method of making a such screen printing form.

At the Screen printing process is printing ink with a squeegee through a sieve through on a material to be printed (also substrate or Substrate called) printed. That is why the screen printing process also often referred to as a printing method. In conventional Screen printing methods are used screen printing forms, which is a full-surface Sieve, which is often formed as a fabric have. At those parts of the fabric where no color is printed should, the through holes of the fabric are through a additional layer rendered opaque Service. Accordingly, the tissue or the sieve in the places where color is to be printed through, permeable to color. This color-permeable area represents the printing area (also called image area) is.

to Production of printing plates it has been known to use a tissue a photosensitive layer, then a film covering the photosensitive layer in regions hang up and expose. After exposure, wash out and a drying of the sieve. In general, the part of the photosensitive Washed out coating that was not under the influence of light so it was covered by the movie. Subsequently, with the fabric or wire a printing forme are produced. The generating of printing plates by means of exposure and subsequent washing is very expensive.

One Disadvantage of tissues is that the through holes for the colors, so the meshes, often through the thickness of the threads for the tissue or by the weaving process are limited. In addition, the tissues exhibit in the places where the threads intersect, another Thickness than in the areas between the intersections. This can negatively affect the printed image.

Further Problems may arise when the printing structure is finer and smaller than the opening between the threads. Metal mesh must be mechanically stabilized by galvanic means and be stiffened. Furthermore, woven structures meet the requirements on the microstructure dimensions, hole densities, tolerances and side surface precision not fully fair. Tissues have a missing mechanical Stiffness, resistance and stability Kinking, wrinkling, wrinkling, bulging and in the case of Cylinder turning on. Incorrect handling exists the danger of destroying the printing form.

From the DE 19 60 723 A It is known to produce the printed pattern in the metal layer with a plastic film coated on one side with metal by means of a photo-etching technique and then to produce the screen pattern in the plastic layer. It is also provided that in the plastic layer, the screen pattern is generated over all areas of the printing plate, ie both in the printing area and outside the printing area. This method for producing a screen printing form is relatively complex.

task the present invention is to provide a screen printing form, which is particularly easy to manufacture and which to influence the printing result can be designed.

Solved This object is achieved by a Screen printing form of the type mentioned, wherein the film exclusively perforated in a printing area by means of a laser. Consequently Both the printing form and the screen can simultaneously in the printing area getting produced. This has the advantage of no cover / coating is necessary to keep the openings of the sieve outside to cover the printing area. In just one operation you can thus the template / mask and the perforation for the color passage getting produced. The printing form can be produced quickly and safely.

It no lithographic process is necessary. The screen printing form has no photosensitive layer, so no aging can be done. The screen printing form according to the invention is storable as it is not a photosensitive layer is available. Unlike conventional sieves, the packed and delivered together with the photosensitive layer no light and air tight packaging is required.

at the cleaning of the screen printing form does not have to be taken care of that a layer applied to the film is damaged and thus the printing form is damaged. The screen printing form is therefore suitable for high loads. Cleaning as well Removal and installation are easy. To create the print area is digital technology applicable.

Further Benefits arise when the film is single-layered. This also simplifies the manufacturing process. Furthermore can the screen printing form be produced inexpensively, because on the one hand fewer process steps are needed and on the other hand, the material for the screen printing mold more cost-effective is.

The foil can be made of metal, in particular Stainless steel or titanium, or plastic be formed. A formed of metal screen printing or film has the advantage that it can be exposed to high stresses. Metal foils are not susceptible to distortion, waviness and bulging. For rotary printing plates results in a large axial stiffness.

at An embodiment of the invention can be provided that the Film has a thickness in the range 15 to 400 microns, preferably in the range 30 to 80 microns. By choosing one very small thickness, z. B. in the range ≤ 20 microns it is possible to produce only a small color pad. Thus, a very thin paint can be done, so Printing ink can be saved. If, on the other hand, a film has a thickness has in the range 400 microns, so the inventive Screen printing form can be used to generate braille. The printed color thus gives a height that feels can be. A sufficient paint application can with film thicknesses be ensured in the range 30 to 80 microns.

at an embodiment may be provided that the Perforation of less than 75%, preferably less than half of the total area of the film extends.

Of the Perforation diameter can range from 10 to 280 microns lie. By using a laser to create the perforations It is possible to make the perforation diameter very small hold, z. B. in the range 10 to 40 microns, preferably 10 bis 20 μm, so that a good resolution can be realized is.

According to one Embodiment may be provided that the size the perforations in a pressure range varies. The variation may be such that the hole size (diameter the holes) towards the edge of the printing area decreases to create clearly defined edges.

In the screen printing form according to the invention, it can be provided that the perforation density is> 100 / mm ² , preferably> 250 / mm ² , very preferably ≥ 300 / mm ² , in particular ≥ 625 / mm ² . Thus, it is possible to produce a screen printing form with a very high density of perforations. This can positively influence the print result. Assuming a hole diameter of 20 .mu.m and a web width between the holes of likewise 20 .mu.m results in a hole density of 625 / mm ² .

The Perforations can be arranged in rows and the Perforations of adjacent rows can side by side lie. However, this results in different web widths. If, however, little material and a uniform Web width between the perforations desired, so can the Perforations are also arranged in rows, with the perforations adjacent rows are arranged offset from one another. This means, that the perforations are arranged on a gap. This corresponds essentially to an arrangement "in the triangle"; d. H. Holes are at the corners of an equilateral triangle arranged.

ever according to the desired print image and printing process the perforations are designed differently. For example can they in a plan view circular, oblong, oval, polygonal, especially triangular, four-hexagonal or octagonal be educated. It is also conceivable different perforation designs for the same pressure range or different pressure ranges to use the same screen printing form.

Special Benefits arise when the perforations at the edge of a printing area have a different shape than the farther from the edge Perforations of the same printing area. This makes it possible To produce print images with very sharply defined edges. at conventional sieves made from a fabric were needed, especially for oblique edges the meshes are only partially covered or a narrow polymer web over a stitch are created away. This has sometimes been difficult shown. In a screen printing form according to the invention It is possible even sharp edges are sharply defined manufacture or print by the shape, size and / or arrangement of the perforations depending on the printed image can be selected.

at a particularly preferred embodiment may be provided be that the webs between the perforations a smaller thickness or height have as the film outside the printing area. Thereby can be created in the printing area room for color. Thus, a sufficiently thick color pad can form to ensure that with adequate paint in the print area is printed.

For Some printing applications may be advantageous if the perforation density varies in a pressure range. This allows the amount applied Color to be adjusted.

alternative or additionally, it may be provided that the film thickness varies in a pressure range or in different pressure ranges. Consequently For example, lines of different heights can be used be generated.

The perforations can be cylindrical, ko nisch, biconical, conical, stepped and / or bulbous. This means that all the above forms for the perforations can be combined with each other. The screen printing form can be reworked, z. B. nano-coated, be. A screen printing form which has a material layer, for example metal, in which the perforations are formed and carries nano-coating, is considered as single-layer in the sense of the invention. The screen printing form can be flat or cylindrical. The latter is suitable for rotary screen printing.

In The scope of the invention also includes a method of the type mentioned above, wherein in a film by means of a laser Perforations are placed in a pressure range. By the Using a laser can make the perforations very accurate To be defined. In addition, very small Perforations are generated. The generation of perforations can automated. For example, the laser based on a digital image of the print area are driven to the perforations to produce in the film. Preferably, the perforation is carried out by means of Laser only in the printing area.

Special Benefits arise when a chilled, in particular water jet guided laser is used. This can a heating of the film during insertion of the perforations be reduced or avoided altogether. Thus can be avoided be that the film warps when introducing the perforations or deformed. Burnup can be carried away by the water so that a clean surface is created. A small one Heating can also be done with a fast pulsed laser, eg. B. in the picosecond range can be achieved.

The Foil may be before or after perforation in a cylindrical shape to be brought. This makes it possible to use the printing form to use in a rotary screen printing process. in principle it is conceivable already a cylindrical printing form with perforations to provide.

The Perforations can be in a continuous process be introduced when the film before the perforation of a Roll is unwound and / or wound up after the perforation becomes.

To the perforation, the film can be aftertreated. For example the foil can be deburred or nano-coated. A nano coating has the advantage that the flow behavior of the color influences can be.

While the perforation can vary the perforation density on the film become. This can be done by a corresponding control of the laser. Furthermore, in the printing area, the thickness of the film can be reduced, for example, by material removal using the laser. This can more color can be stored in the print area.

Further Features and advantages of the invention will become apparent from the following Description of embodiments of the invention with reference to FIG Figures of the drawing showing details essential to the invention, as well as from the claims. The features shown there are not necessarily to scale and such illustrated that the features of the invention clearly visible. The different Features can be individually or individually realized in any combination in variants of the invention be.

In the schematic drawing are embodiments of Invention and closer in the following description explained.

It demonstrate:

1 a plan view of a first embodiment of a screen printing form for displaying a printing area;

2 a plan view of a screen printing form to represent different perforation forms;

3 a plan view of a screen printing form to illustrate the combination of different perforations;

4a to 4b Representations of different perforation cross sections;

5 a cylindrical screen printing form;

6 a plan view of a screen printing form to represent different Perforationsdurchmesser.

In the 1 is a screen printing form 10 shown a slide 11 which has perforations 12 contains. The perforations 12 are introduced by means of a laser and are only in a pressure range 13 , This means that by means of a squeegee printing ink over the surface of the screen printing form 10 can be moved and through the perforations 12 can be pushed through, so that an application of paint on a substrate, such as paper or textile results. Areas of the film 11 outside the print area 13 have no perforation.

In the 2 is a screen printing form 20 shown, the perforations in a plan view un are designed differently. The perforation 21 is circular, the perforation 22 is quadrangular, especially square, the perforation 23 has the shape of a long hole, the perforation 24 is oval, the perforation 25 is hexagonal in a plan view, the perforation 26 is octagonal and the perforation 27 is triangular. In the printing area 28 The perforations are in two rows 29 . 30 arranged, with the perforations of adjacent rows 29 . 30 staggered to each other, so on gap, are arranged.

The screen printing form 40 of the 3 has a print area 41 with two types of perforations 42 . 43 on. The perforations 42 in the edge area of the printing area 41 have a different shape than the perforations 43 that lie away from the edge. The perforations 42 are aligned so that there is a clearly defined oblique line in the print image.

The 4a to 4e show cross-sectional views of a film 50 , It is easy to see from the illustrations that the film 50 single layer is formed. The perforation 51 in the 4a is shown has straight sidewalls. In a plan view, it is circular, so that the perforation 51 is cylindrical.

The perforation 52 of the 4b is conical. The perforation 53 has a biconical shape. The perforation 54 is bulbous, and the perforation 55 is stepped.

The 5 shows a cylindrical screen printing form 60 in which the film 61 that the pressure area 62 with the perforations 63 carries, was brought into a cylindrical shape. The screen printing form 60 can be used in a rotary printing process.

The 6 shows a Siedruckform 70 with a pressure range 71 where the size of the perforation is at the edge of the print area 71 changes. The perforations 72 are smaller or have a smaller diameter than the perforations away from the edge 73 ,

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 1960723A [0006]

Claims (24)

Screen printing form ( 10 . 20 . 40 . 60 . 70 ) for graphic applications with a perforated foil ( 11 . 50 . 61 ), characterized in that the film ( 11 . 50 . 61 ) exclusively in a printing area ( 13 . 28 . 41 . 62 . 71 ) is perforated by means of a laser. Screen printing form according to claim 1, characterized in that the film ( 11 . 50 . 61 ) is formed in one layer. Screen printing form according to one of the preceding claims, characterized in that the film ( 11 . 50 . 61 ) made of metal, in particular stainless steel or titanium, or plastic is formed. Screen printing form according to one of the preceding claims, characterized in that the film ( 11 . 50 . 61 ) has a thickness in the range 15 to 400 microns, in particular in the range 30 to 80 microns. Screen printing form according to one of the preceding claims, characterized in that the perforation over less than 75%, preferably less than half the total area of the film ( 11 . 50 . 61 ). Screen printing form according to one of the preceding claims, characterized in that the perforation diameter in the range 10 to 280 microns. Screen printing form according to one of the preceding claims, characterized in that the perforation density is> 100 / mm ² , preferably> 250 / mm ² , very preferably ≥ 300 / mm ² , in particular ≥ 625 / mm ² . Screen printing form according to one of the preceding claims, characterized in that the perforations ( 12 . 21 to 27 . 42 . 43 . 51 to 55 . 63 . 72 . 73 ) in rows ( 29 . 30 ) and the perforations of adjacent rows ( 29 . 30 ) are arranged side by side or offset from one another. Screen printing form according to one of the preceding claims, characterized in that the perforations ( 12 . 21 to 27 . 42 . 43 . 51 to 55 . 63 . 72 . 73 ) in a plan view circular, oblong, oval, polygonal, in particular three, four, six or octagonal are formed. Screen printing form according to one of the preceding claims, characterized in that the perforations ( 42 ) at the edge of a printing area ( 41 ) have a different shape than further from the edge perforations ( 43 ) of the same print area ( 41 ). Screen printing form according to one of the preceding claims, characterized in that the size of the perforation ( 72 . 73 ) varies in a pressure range, in particular decreases towards the edge of the pressure range. Screen printing form according to one of the preceding claims, characterized in that the webs between the perforations have a smaller thickness than the film ( 11 . 50 . 61 ) outside the printing area ( 13 . 28 . 41 . 62 . 71 ). Screen printing form according to one of the preceding claims, characterized in that the perforations ( 12 . 21 to 27 . 42 . 43 . 51 to 55 . 63 . 72 . 73 ) are cylindrical, conical, biconical, conical, stepped, and / or bulbous. Screen printing form according to one of the preceding claims, characterized in that the perforation density in a printing area ( 13 . 28 . 41 . 62 ) varies. Screen printing form according to one of the preceding claims, characterized in that the film thickness in a printing area ( 13 . 28 . 41 . 62 ) or varied in different pressure ranges. Screen printing form according to one of the preceding claims, characterized in that the film ( 11 . 50 . 61 ) is post-processed after the perforation. Screen printing form according to one of the preceding claims, characterized in that it is flat or cylindrical is. Process for producing a screen printing form according to one of the preceding claims, characterized in that in a film ( 11 . 50 . 61 ) by means of a laser perforations ( 12 . 21 to 27 . 42 . 43 . 51 to 55 . 63 . 72 . 73 ) in a printing area ( 13 . 28 . 41 . 62 ) are introduced. Method according to claim 18, characterized that a cooled, in particular water jet Laser is used. Method according to one of the preceding claims 18 or 19, characterized in that the film ( 11 . 50 . 61 ) is brought into a cylindrical shape before or after the perforation. Method according to one of the preceding claims 18 to 20, characterized in that the film ( 11 . 50 . 61 ) is unwound from the roll before perforation and / or wound up after the perforation. Method according to one of the preceding Claims 18 to 21, characterized in that the film ( 11 . 50 . 61 ) is post-treated after perforation. Method according to one of the preceding claims 18 to 22, characterized in that during the perforation the perforation density is varied. Method according to one of the preceding claims 18 to 23, characterized in that in the pressure range ( 13 . 28 . 41 . 62 . 71 ) the thickness of the film is reduced.