DE19860640A1 - Separation element for screen printing forms is made of silicone to eliminate the need for use of an additional adhesive substance between the separation element and the printing screen - Google Patents

Abstract

The separation element (1) is made of silicone to eliminate the need for use of an additional adhesive substance between the separation element and the printing screen (4).

Description

The invention relates to separators made of silicone and a method for the production this separators according to the preamble of the independent claims.

These dividers are required for special printing processes, namely the Printing, also known as screen printing, screen printing or stencil printing.

When printing, the printer ink passes through the open areas of the Printing form on the fabric to be printed. A template is used as the printing form used, which using a screen mat material for Uniform color distribution made of metal, textile or plastic threads becomes. The printing process itself is that the printing ink is printed using a Squeegee is stroked over the screen printing form and thus into the stencil uncovered openings and finally through them onto the one below lying substrate is brought. This can be done manually using a so-called Hand squeegee, which is a solid cross piece with rubber strips, or also done automatically.

The screen printing forms used in banknote printing, which are framed from Flat sieves exist, have dividers to close the two at the same time  separating printing colors from each other. These bridges, also chunks are made of wood, wood composite or cardboard, just like that Frame material, i.e. from a relatively stable and stiff material. you will be glued to the sieve using suitable glue, which creates the disadvantage can cause tension when sticking between the separator and sieve occurs and thus through the stress process while printing it to quality problems, up to the tearing of the tissue. In addition, these dividers are not always parallel, but also glued in somewhat obliquely, creating an uneven distance to the squeegees arises in the manufacturing process between the frame and separator be moved. Due to this non-parallelism between the frame and separator the squeegee has to be labor-intensive, which makes the Manufacturing process paint is deposited and dries, which too Printing problems can lead to tearing of the tissue.

Also, when gluing such webs, the adhesive used for this occurs Sides of the webs, which causes the squeegees of the screen printing machine on this Place on the hardened adhesive during the manufacturing process and can tear the sieve.

To avoid this, you can keep the squeegee narrower, but that's too another disadvantage, namely the color in the doctored Area can get there, dry up and again the same problems in terms of print quality and risk of tearing the screen as with the previous one described in the squeegee adhesive entered. This above mentioned disadvantages can be avoided by changing the sieve frequently, with costs of downtimes and rejects at restart, of course as well as material costs of the screens and material costs of the excess paint arise.

The object of the invention is now to provide a device and a method Manufacture to provide this device that is economical Reduces or circumvents disadvantages as described above. So it should be without great effort an economically and ecologically improved separator are provided, and a method for producing this separator be shown.  

The technical teachings of independent claims.

It is essential that the separators of the sieves are made of silicone massive ridges are required because of the larger amount of paint should be used, which the otherwise usual low webs from the would flood usual materials.

A negative mold is used, the surface of which is coated with For example, Teflon that no silicone can adhere. This shape can fit snugly put the sieve and against the edges by means of conical wedges Sieve frames are fixed. The cutouts in the mold are made with silicone filled and the surface smoothed. After curing, the shape can removed and the remaining distances between the silicone web and Screen frames can be sprayed on by hand.

The advantages of the process are, on the one hand, lower screen consumption and lower Downtimes, less scrap when restarting and the possibility of variable adaptation of the printing forms to the special ones Production requirements.

Using the proposed method, the dividers can be absolutely Apply in parallel and without pre-tensioning the sieve. The parallelism is through the predetermined basic shape and its arrangement in the sieve is forcibly generated. Through the use of flexible silicone, this web can Adjust the strain of the sieve and thus prevent tension.

When producing the dividers, the prepared shape for the dividers is used inserted into the printing screen and through the arrangement of the filling material remaining strips filled with silicone. The excess silicone can then be scraped off and the mold removed after the silicone has dried become.

Here, on the one hand, silicone-working plastics are used for the negative mold used and for the divider itself, commercially available silicone cartridges.  

The subject matter of the present invention does not only result from the subject of the individual claims, but also from the Combination of the individual claims.

All disclosed in the file, including the summary Information and features, especially those shown in the drawings spatial education are claimed as essential to the invention, insofar as they individually or in combination are new compared to the prior art.

In the following, the invention will be explained using only one embodiment illustrative drawings explained in more detail. Here go from the drawings and its description further features and advantages of the invention Invention.

The figures show in detail:

Fig. 1 shows a perspective view of the structural principle of the printing apparatus with the inventive silicone web.

Fig. 2 shows a section along the line II through the screen printing device with the silicone web according to the invention.

In FIG. 1 is a perspective view of the construction principle of the screen printing device is as inventive silicone rack one to see. This separating web 1 made of silicone therefore rests on the printing form 4 and divides the clamping frame 3 roughly in half. The separating web 1 is positioned within the clamping frame in such a way that it lies essentially parallel to the lateral clamping frame parts 3 b approximately in the middle of these parts, and secondly, approximately at right angles to the upper and lower clamping frame parts 3 a. The height of the separating web 1 can be taken into account depending on the requirements in the manufacturing process of these dividing webs and the heights of these dividing webs can also be freely selected by the inventive method of the dividing webs, the height normally representing at least the height of the clamping frame parts. Between the separating web 1 and the respective clamping frame side parts 3 b, a hand doctor blade 5 is then moved up and down in the direction of movement 7 in the direction of the clamping frame parts 3 a during printing. Thus, the color, which is located within the tenter frame 3, is pressed evenly through the printing form 4 , which is composed of a screen and a stencil, onto the printing material 6 to be printed, in this case banknotes or shares.

FIG. 2 shows a section along line II through the screen printing device according to FIG. 1, only the silicone separating web 1 and the surrounding area being shown in more detail here. There is shown a state during the process of manufacture of the silicone separating web, in which case the two female mold parts 2 a and 2 b are ncch not decreased. The injected silicone 1 in the form of the separating web is located between these two negative molded parts 2 a and 2 b, and the material of the negative molds 2 a and 2 b is selected such that at least the contact surfaces 12 a and 12 b, and the contact surfaces 13 a and 13 b these negative molded parts are silicone-repellent, for example coated with Teflon.

It is also easy to see that the injected silicone comes into intimate contact with the printing form 4 at the contact point and thus a firm connection area 10 is created between the separating web 1 and the printing form 4 around the forces which occur due to the doctor blade 5 during the printing process to be able to record. This is also an essential difference to the conventional separators, in which the adhesive also forms an intimate connection with the printing plate 4 , but the connection between the adhesive and the separator 1 causes such problems that the separator 1 is constantly detached when using the Tenter frame 3 comes, which also leads to quality defects in the printing.

It is also shown here that the surface 11 of the separating web 1 must still be smoothed out during the manufacturing process of the separating web in order to achieve clean processing.

Drawing legend

1

Separator

2nd

negative form

3rd

Stenter

4th

Printing form

5

Squeegee

6

Print material

7

Direction of movement

8th

-

9

-

10th

Connection area

11

surface

12th

Touch surface

13

Contact surface

Claims (9)

1. separator within a stenter in screen printing, the separator ( 1 ) between the stenter parts ( 3 a, 3 b) and the stenter part ( 3 a) is arranged substantially at right angles and to the stenter parts ( 3 b) in are arranged essentially parallel to it, characterized in that the separating web ( 1 ) consists of silicone, as a result of which no additional adhesive is required between the dividing web ( 1 ) and the printing form ( 4 ). 2. Separator according to claim 1, characterized in that after the manufacture of the separator ( 1 ) there is no more silicone in the squeegee area between the clamping frame ( 3 ) and the separator ( 1 ). 3. Separator according to one of claims 1 or 2, characterized in that the separator ( 1 ) enters into a material connection with the printing form ( 4 ) in the connection area ( 10 ) of these two parts. 4. Separator according to one of claims 1 to 3, characterized in that the width and height of the separator ( 1 ) can be adjusted by varying the negative shape ( 2 ). 5. Separator according to one of claims 1 to 4, characterized in that the separator ( 1 ) can be adjusted in length by varying the clamping frame parts ( 3 b). 6. Separator according to one of claims 1 to 5, characterized in that the height of the separator ( 1 ) comprises at least 25% of the height of the clamping frame ( 3 ). 7. separator according to one of claims 1 to 6, characterized in that the parallelism between the separator ( 1 ) and the clamping frame parts ( 3 b) can be essentially ensured without measuring effort. 8. Separator according to one of claims 1 to 7, characterized in that the right angle between the separator ( 1 ) and the clamping frame part ( 3 a) can be ensured essentially without measurement effort. 9. A method for producing a separating web ( 1 ) from silicone according to claims 1 to 8, characterized in that this method comprises the following steps:

• a) inserting the variable negative mold ( 2 ) in the clamping frame ( 3 ) and essentially central positioning;
• b) filling the negative mold ( 2 ) with silicone until the separating web is formed;
• c) smoothing the surface ( 11 ) of the separating web ( 1 );
• d) scraping off the excess silicone in the doctor area of the separating webs ( 1 ) by the doctor blades ( 5 );
• e) removing the negative mold ( 2 ) after the silicone of the separating web ( 1 ) has dried