EP0925195B1 - Printing device with a flexible screen printing form in a printing frame and screen printing form for it - Google Patents

Abstract

The invention relates to a screen printing fabric made of self crossing plastic threads with an emulsion coating, wherein the plastic threads are coated with a vacuum metallized or sputtered encasing layer which is covered by an emulsion bearing metal coating produced by electroplating.

Description

The invention relates to a printing device with a flexible screen printing form made of plastic fabric in one Printing frame according to the preamble of claim 1. The invention also includes a screen printing form Screen printing fabric made of intersecting plastic threads as Carrier of a coating from a - in particular photosensitive - emulsion according to the generic term of Claim 16

US-A-5,111,743 describes a printing device a flexible screen printing plate made of a textile-like fabric, the silk, nylon, polyester or the like. Threads is made or from stainless steel wires. Also metal plates with an etched hole system are mentioned. This screen printing plate is on two parallel edge areas clamped in a printing frame, between which a Rubber scrubber pushed back and forth to apply ink can be.

One of the panel edges is with - through one frame side - Screws fixed, the opposite Plate edge can be fixed by means of a and in Printing frame with part of the frame bearing the game moved become; a central rod is provided on the latter, the one with its free end pointing outwards passes through adjacent frame side, against their The outer surface is supported by a coil spring.

JP-A-60262689 (Sono Kogyo K.K.) discloses one Screen printing form with intersecting plastic threads Nickel coat as a support for a photosensitive Coating.

The screen printing process is - centuries after its first Application in China - since about the 19th century in Europe known; a fine-mesh textile or wire mesh is stretched in a screen printing frame and attached to the non-image Areas covered in opaque colors. In addition to manual Cutting templates - for example for inscriptions - are today preferred direct or photographically produced Indirect stencils common; the choice of stencil type - for direct stencils, those with emulsion, with direct film and emulsion or with direct film and water - remains left to the screen printer.

It usually takes to produce a screen printing form several steps. First, a screen printing fabric is placed over one Print frame made of light metal, wood or the like. spanned and glued to the print frame in its tensioned position. A Cleaning the fabric enables subsequent application a light-sensitive emulsion, for example under Use of a coating trough manually or mechanically with a coating machine. Because the coating is not can be generated exactly up to the inside of the frame The remaining surface can be subsequently sealed with a screen filler. Now the coated surface is by means of a Exposed image corresponding copy template (film) exposed. The unexposed areas of the printed image are washed out.

After the washout process, the actual screen printing template is created, whose marginal zones are often still covered have to. Once these covers have dried, you can use the stencil can be printed. In addition, the individual Devices designed for the respective manufacturing steps of the Stencil can be used to clean. So the workload for the production of a screen printing stencil-- especially a single template - relatively large.

For certain areas of application, it is known for plastic nets by chemical treatment of the surface to settle on these palladium seeds and the filaments to metallize. These chemical treatment processes take place over several stages and are in their compositions and processes on the respective plastic material vote. There are restrictions on the choice of materials given due to poor or unsuitable materials. One can use the known expensive pretreatments expensive chemical metal deposition can be connected; because of its insufficient conductivity, the pretreated can Plastic surface not directly with a galvanic Cover metal deposit.

Another point of view is that today in screen printing used template carrier before applying the actual Template stretched on a frame on all sides and be glued. The quality of the print depends on it of the correct tissue tension, the relaxation of the Fabric, the set jump, the squeegee or the like. Circumstances. So that the set jump between tissue and print object can be overcome is an elongation the template is necessary. This leads to template carriers without - or with only very little - self-expansion high train alternating loads that lead to rapid fatigue the template holder or at most to destroy it being able to lead.

Because with these low-stretch stencil carriers in flat screen printing can be printed correctly is a Print frame necessary, which caused by the jump Can compensate for changes in length.

US-A-3,303,777 describes a holder for a stencil on a screen printing machine in which they work on two parallel ones Areas - which indicate the direction of movement displaceable, pressing the printing inks through sieve meshes Cross squeegee - to be fixed and tensioned.

US-A-1,934,643 from 1930 describes a fabric made of electrically conductive material, the surface of which is a non-metallic cover layer or a cover layer Made of pure metal or an alloy, especially with Nickel or chrome, by spraying, plating or a chemical or galvanic process becomes.

US Pat. No. 4,042,466 shows a method for producing a fabric web made of a textile fabric for use as a screen printing stencil, the web of which is provided with a metallic cover layer. For this purpose, the plastic threads are coated with a thin metallic layer of for example copper having a thickness 1 to 2 μ m as a conductive intermediate layer, and in this a nickel layer of 25 μ m is electrodeposited.

Knowing these facts, the inventor did it Goal set, the use of screen printing forms or - to considerably simplify stencils in printing units and to make it more user-friendly as well Increase register accuracy - even with long runs. In addition, the print quality for fine lines and screens should be thanks to a homogeneous coating with a constant structure be optimized.

With regard to the printing frame, the use of stencil carriers is intended enables without self-expansion as well as by the mentioned jump caused length changes - and so that changes in tension of the template are eliminated. Minimal stencil tensioners are said to have minimal squeegee pressures allow, resulting in reduced wear and tear of Stencil and squeegee guides. Tensioning the screen printing stencil in only one direction allows a constant specific squeegee pressure across the printing width.

According to the invention, the screen printing form consists of Printing device made of a metallized plastic fabric, the provided with a metallic coat layer and this in turn from a metal coating carrying the emulsion is covered, with the plastic fabric of both Provide fabric sides with the metallic jacket layer and then electroplated; Connecting elements are as profiled connecting strips or bearing profiles provided, one with the as a clamping beam trained movement element is connected. From the Metallized plastic mesh can be used for screen printing plates Cut predetermined format size.

The screen printing form or screen printing plate is - below Interposition of two parallel plate edges arranged connecting strips - on the one hand Frame side of the printing frame and on the other hand on an in this can be moved parallel to that side of the frame Clamping beam set. The tensioning beam is transverse to Direction of movement of one that penetrates the printing inks Squeegee. Thanks to this type of attachment in two Squeegee crossing areas - and unpaved Longitudinal edges - will distort the print result Sag in the form of a cross section between the Avoid chain lines arising along the edges.

Due to the special design of two edge zones of the Screen printing plate can do this very easily on the printing unit placed in a printing frame and tensioned. To should special connection or attachment profiles to the Plate ends are attached. But also the attachment a perforation for hanging the plate ends falls into the Scope of invention.

For handling, especially with large stencil formats the use of strips in the Trailer area or a closed thin-walled frame made of sheet metal or the like Material in the size of the Screen printing plate possible.

The metallization of the fabric according to the invention results in a sufficient angular strength with the result that the screen printing plate only has to be tensioned in one direction and still no register differences across the clamping direction arise. This one-sided clamping also allows that the print image laterally to the edge of the screen printing plate can be placed; there is only room for to keep the attachment of a color border that is stuck on, welded, sewn or otherwise attached can be.

The screen printing plate has proven to be cheap exciting clamping beam using energy stores within the Print frame to one of its frame side or on Connect frame profile.

To the clamping position of the clamping beam or the clamping and Adjusting the printing position of the screen printing plate can, according to the invention mechanical, pneumatic, hydraulic or other Means are used.

The screen printing plate is intended to facilitate the printing process at a distance from a surface to be printed become.

Various forms of are of inventive importance so-called connection or connection strips. So one becomes cross-sectional about an S-shaped angled connecting strip, the cantilever legs in the tensioned position on the one hand Lower edge of the frame side - or the clamping beam - as well as a shoulder in the undercut interior the hollow side of the frame - or the hollow clamping beam - lies on. Another is angled in an S-shape The connecting strip has its cantilever leg in the tensioning direction a bearing surface one in the interior of the hollow Frame side or the hollow clamping beam one Expansion shaft.

The shape of another connecting bar is one against the plane of the screen printing plate inclined hook bar, which in an oblique groove on the frame side or the clamping beam can be used is trained. Another connection bar is with one from the plane of the screen printing plate at an angle curved cantilever leg provided in an equally inclined slanted slot of the frame side or the Clamping bar is designed to be used.

Within the scope of the invention, a screen printing form is included Screen printing fabric made of intersecting plastic threads as Carrier of a coating from an emulsion for a Printing device of the type described above, in which the Plastic threads with a vapor-deposited, plasma-sprayed or sputtered cladding layer of at least one metallic material are coated, which in turn by one that carries the emulsion, by galvanization resulting metal coating is covered; the metallic Material is on both sides of the screen printing fabric on this sprayed, evaporated or sputtered, this possibly several times.

The plastic threads are thus vapor-deposited Coat layer covered, which in turn by one - the Emulsion-bearing - created by galvanization Metal covering is covered. According to another characteristic the invention, the plastic fabric can also by so-called sputtering - by sputtering - with the Cladding layer to be prepared for electroplating.

In both cases, a cladding layer made of metallic Material that prefers gold, silver, nickel, copper, Steel and / or a light metal - especially aluminum - Contains alone or as an alloy.

In the mentioned vaporization or sputtering process for the screen printing fabric according to the invention, layer thicknesses of generates about 5 to over 200 nanometers - especially over 50 nm, which depending on the type of fabric and type of vapor deposition surface resistance from less than 0.2 ohm / 2 to a few hundred can have ohms / 2.

Due to the dry process step of vapor deposition, the Cathode sputtering - i.e. the sputtering mentioned - or Plasma spraying in a vacuum makes electrical conductivity of the fabric.

The mechanical properties of this conductive fabric are mainly determined by its metallization, for example by means of galvanic nickel plating. The Elongation becomes striking with increased strength of the fabric reduced as well as its sliding resistance - regardless of the type of starting tissue - greatly increased. The Metallizing substances contribute above all to strength at the binding points of the tissue. Plastic base materials and form a conductive surface. This makes it possible to use metalized metal to make expensive metallic fabrics Plastic fabrics with similar properties too replace.

As the basis for the - ready-made and with coating provided - screen printing plate is thus a metallized Plastic fabric used, preferably with a metal coating made of nickel because of its general strength. The metallic surface of the screen printing plate reduces the wear of the stencil, resulting in the latter very high print runs can be realized. The conductive Surface of the screen printing plate prevents static Charges. Restrictions on substrates or Colors due to structural problems can practically be excluded become.

The metallized plastic fabric according to the invention ensures minimal strains with sufficient basic strength and causes barely measurable register differences are present on the template, regardless of the set one Tension train.

The mechanical full-surface coating of the limited flexibility metallized fabric causes a high, reproducible Stencil quality with excellent edge sharpness and exact color dosage. A protective film, if applicable reduces mishandling, which is a loss of Could cause coating quality. Because the coating on the endless roll of fabric is eliminated Masking work, as is common today.

It turned out to be cheap, from the metallized Plastic mesh screen printing plates of predetermined format sizes to cut. These can mainly be on two opposite Edges with fasteners for fixing to be provided on a printing frame - preferred connecting elements are profiled connecting strips, between which the relatively rigid screen printing plate extends.

The aforementioned cutting of the screen printing plates to fixed format sizes - which, if necessary, additionally with a pass hole can be provided - enable the end user a standardized workflow that works directly with the precisely fitting exposure of the screen printing plate begins. To washing and drying the screen printing plate can be used for printing.

Thanks to this new type of screen printing plate, there is again manufacture of a single one that failed during its use Screen printing stencil possible in a very short time.

According to a further feature of the invention, in a further embodiment, the screen printing plate has a keder bead on each of two parallel edges, which bead can be inserted into a bearing profile as a connecting element.
Thanks to these requirements, the screen printing plate consists of a metallized plastic fabric, which is machine-coated with a light-sensitive substrate and possibly protected on the coating side with a film. This eliminates all the preparatory work customary today in the production of screen printing stencils; the screen printing plate can be exposed and developed directly.

Furthermore, the metallic surface of the Stencil carrier has extensive chemical resistance as well high mechanical abrasion resistance.

The mechanical coating guarantees a constant high print quality with brilliant edge sharpness and more precise Dosage of the medium to be printed.

The use of this screen printing plate shortens the stencil manufacturing process considerably and eliminates possible sources of error in print preparation.

Another advantage is that the degree of utilization the screen printing plate - the ratio of the printable Area to total area - far above that of a conventional one Tissue lies, possibly doubled.

Due to the high inherent stability of the screen printing plate as well their angular rigidity is also only one-sided The printing plate can be clamped during the printing process. Despite the exclusive tensioning in the doctor direction no significant register differences across the clamping direction noticeable. This is in the doctor direction a plate mounting position fixed (start of printing) and the other (print end) designed to be movable. Is the screen printing plate clamped, the preload force of the spring or pneumatic or hydraulic. Will the screen printing plate due the jump down by the squeegee, this change in length is thanks to the movable attachment the screen printing plate compensated. The resilience on them remains constant and independent of the selected jump, and it is not a swell due to overcoming exposed to the jump. Because the screen printing plate only is tensioned on one side, no additional steps occur Loads due to transverse stresses.

The squeegee pressure remains minimal since there are no deformations of the print carrier are to be overcome. The doctor blade load over the printing width is constant because of the known additional forces at the squeegee ends due to the lack of transverse tension omitted.

• Der Druckrahmen ermöglicht -- dank einer einseitigen beweglichen Schablonenhalterung -- den Einsatz von Siebdruckschablonen mit äußerst geringer Eigendehnung;
• die Spannbelastungen auf den Siebdruckschablonenträger können mittels Druckrahmen gering gehalten werden, was zu minimalen Rakeldruckeinstellungen genutzt werden kann, Verschleiß von Druckplatte und Rakel werden dadurch minimiert;
• der Druckrahmen erlaubt das paßgenaue Drucken mit Siebdruckplatten; es entfallen die Längenänderungen der Schablone aufgrund der Absprungüberwindung sowie Längenänderung der Schablone aufgrund ungleicher Rakelreibkräfte;
• die fehlenden Wechselbelastungen auf den Schablonenträger dank dem konstanten Spannzug im Druckrahmen erhöhen die Standzeit der Siebdruckplatte.

For example, there are the following advantages:

• The printing frame enables - thanks to a one-sided movable stencil holder - the use of screen printing stencils with extremely low internal expansion;
• the clamping loads on the screen printing stencil support can be kept low by means of a printing frame, which can be used for minimal squeegee printing settings, wear on the printing plate and squeegee are minimized as a result;
• the printing frame allows precise printing with screen printing plates; there are no changes in the length of the template due to the jump over and jump in length due to unequal doctor blade friction forces;
• the lack of alternating loads on the stencil holder thanks to the constant tension in the printing frame increases the service life of the screen printing plate.

Fig. 1:

einen Querschnitt durch ein Gewebe;

Fig. 2:

eine Schrägsicht auf einen vergrößerten Teil des Gewebes;

Fig. 3:

einen vergrößerten Ausschnitt aus Fig. 2 mit Schrägsicht auf eine Bindung zweier sich kreuzender Fäden;

Fig. 4:

eine geschnittene Schrägsicht auf einen Siebdruckrahmen mit Siebdruckschablone und Rakel;

Fig. 5 bis Fig. 7:

Längsschnitte durch unterschiedliche Ausgestaltungen von Siebdruckrahmen mit Siebdruckschablone;

Fig. 8 bis Fig. 12:

gegenüber Fig. 5 bis 7 vergrößerte Querschnitte durch einen Abschnitt eines Siebdruckrahmens;

Fig. 13, 14:

gegenüber Fig. 5 bis 12 vergrößerte Querschnitte;

Fig. 15, 16:

Skizzen zu Montagehilfen.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawing; this shows in:

Fig. 1:

a cross section through a fabric;

Fig. 2:

an oblique view of an enlarged part of the tissue;

Fig. 3:

an enlarged section of Figure 2 with an oblique view of a binding of two crossing threads.

Fig. 4:

a cut oblique view of a screen printing frame with screen printing stencil and squeegee;

5 to 7:

Longitudinal sections through different designs of screen printing frames with screen printing stencil;

8 to 12:

5 to 7 enlarged cross sections through a portion of a screen printing frame;

13, 14:

5 to 12 enlarged cross sections;

15, 16:

Sketches for assembly aids.

A fabric 10 for making screen printing stencils is made from intersecting warp threads 12 and weft threads 14, 1 in a so-called canvas weave, in the case of a Repeat - one by a certain number of binding sites 16 defined repetition units - two each Warp threads 12 and two weft threads 14 belong. These threads 12, 14 can be made from any plastic base material consist, for example, of polyamide (PA), polyethylene (PE), Polyethylene terephthalate (PET) or the like. more.

The plastic fabric 10 is a roll continuously Steaming process subjected to the maximum web length due to the highest possible winding diameter in the steaming system is determined.

For example, gold, silver, Copper, nickel, steel, aluminum or the like. Noble, colorful, Heavy or light metals - each alone or in combination - used and in coordination with a subsequent one Galvanization.

The evaporation or sputtering process - possibly also a plasma application in vacuum - is carried out on both sides and, under certain circumstances, repeated several times for special requirements. This creates around the thread 12, 14 as the respective plastic core - which is shown in FIG. 2, 3 for better clarity in contrast to the warp and weft thread 12, 14 with 12 _a and 14 _a - a diameter a of, for example, 15 μ m to 100 μ m is clarified in Fig. 3 cladding layer 18 a layer thickness b of about 50 to about 200 μ m, which may have from ohm below 0.5 / 2 to over 100 ohm / 2 depending on the tissue type and of vapor deposition surface resistances.

This dry coating process can also be in the area each bond 16 lead to material accumulations, of which one between the crossing threads 12, 14 is indicated at 20.

On the prepared in the manner described by vaporization Plastic mesh can now be used for direct galvanic metal deposition be made. You can turn any metals can be used, such as Cu, Ni or the like ..

• eine Cu-Bedampfung mit einem Oberflächenwiderstand von etwa 0,5 bis 1 ohm/2 für eine anschließende galvanische Vernickelung oder
• eine Stahl-Bedampfung mit einem Oberflächenwiderstand von etwa 0,4 ohm/2 bis 10 ohm/2 für eine folgende galvanische Vernickelung.

The evaporation material and the evaporation thickness have to be matched to the subsequent electroplating process in order to avoid that the cladding layer 18 is degraded by the electroplating bath, which would reduce or completely eliminate the conductivity of the evaporation during longer exposure times. Combinations for galvanic metallization are

• a copper vapor deposition with a surface resistance of about 0.5 to 1 ohm / 2 for a subsequent galvanic nickel plating or
• a steel vapor deposition with a surface resistance of about 0.4 ohm / 2 to 10 ohm / 2 for a subsequent galvanic nickel plating.

The galvanic metallization can be carried out as a continuous process with practically any roll length and leads to a closed metal coating 22 of selectable layer thickness e - from preferably 2 μm to 20 μm and more - over the entire fabric 10 _a ; this metal coating 22 ensures high mechanical stability, above all sliding resistance, and also chemical resistance of the metallized tissue 10 _a ; its strength is significantly increased with a significant reduction in the elasticity.

Fig. 4 shows in a printing frame 24 a plate-like screen printing stencil or screen printing form 26 made of the above-described manner, metallized fabric 10 _a and fixed to two opposite edges connecting profiles or strips 28. It cannot be seen that the fabric 10 _a with a light-sensitive Emulsion layer is provided, which contains a phototechnically produced printing pattern - to be printed on a printing material 30 attached underneath. The printing material 30 is placed on a printing table at a jump dimension or distance h below the - not shown in FIG. 4 - clamping plane of the screen printing stencil 26; during the printing process, a squeegee 32 guided parallel to those connecting strips 28 over the fabric 10 _a pushes the fabric 10 _a linearly onto the printing material 30. The doctor 32 - also called scraper - here is a rectangular profile with a printing edge 33, the length of which is approximately that of Connection strips 28 corresponds and presses the printing ink on its path of movement through the open screen openings of the fabric 10 _{a in} the printing pattern.

The rectangular printing frame 24 consists of four frame profiles or frame sides 34, which are designed here as hollow profile sections and one of which - referred to as 34 _a - offers an undercut interior 36 for hanging in the one connecting strip 28; the latter is cross-sectionally approximately S-shaped with on both sides of a main strip 28 _a on the longitudinal edges of which cantilevers 29 projecting in opposite directions, one of which is fixed in the interior 36 and the other of which is arranged on the fabric 10 _a and conforms to a lower edge 38 of the hollow profile.

The similarly designed - cross-sectionally counter-rotating - other connecting bar 28 is supported in the manner described in the undercut interior 36 of a - that hollow section 34 _a cross-sectionally opposite in the same way - tensioning bar 40, which with the adjacent parallel hollow section 34 of the pressure frame 24 by coil springs as an energy store 42 is connected and can therefore be moved against the direction of tension x when pressed onto the tissue 10 _a .

The screen printing stencil 26 of a smaller format in FIG. 5 is hooked into the frame profile 34 _b shown there of the printing frame 24 - and likewise in the clamping beam 40 _{b of} the same design - by means of a hook strip 44 inclined against the fabric surface. 11 shows this in more detail.

6 shows a screen printing stencil 26 with the parallel connecting strips 28 described in relation to FIG. 4, which are mounted here on the frame profile 34 _c on an insert shoulder 46 of an additional strip 47 and on the clamping beam 40 _c on a segment shoulder 48 of a clamping shaft 50. These bearings are illustrated in the enlarged representations of FIGS. 8.9.

In FIG. 7, a tension spring 52 presses on a bearing profile 54, which loads a cantilevered nose 56 of the frame profile 34 _d or the tension bar 40 _d ; A keder bead 58 of the screen printing stencil 26 rests in the keder groove 54 in the rod-like bearing profile 54.

The frame profile 34 _e of FIG. 10 receives in an oblique slot 60 a leg 29 _a inclined upward at an angle w of <40 ° of a cross-sectionally approximately angular connecting strip 28 _e . This leg 29 _a is held by a spring-loaded clamping piece 62 of the frame profile 34 _e .

11 illustrates the mounting of the hook strip 44 mentioned above, which engages behind a groove wall 64 of an oblique groove 66 of the frame profile 34 _{b which is} inclined at an angle t of approximately 120 ° against the surface of the screen printing stencil 26.

If a screen printing stencil 26 with a flat connecting bar 28 _{f is} used, then according to FIG. 12 vertical register or tensioning pins 68 of the frame profile 34 _{f reach} through corresponding bores in that connecting bar 28 _f . The latter is held by a screwed to the frame profile 34 _f pressure strip 70 against the supporting surface 72 of the frame profile 34 _f.

13, 14 show a further fastening option for a screen printing plate 26 on a printing table 74. In the oblique groove 66 of a hollow profile 78 provided with two molded-on side strips 76, an air bellows 80 of approximately square cross section is accommodated, which presses on a plastic strip 82 with an outer surface . This in turn lies on a rubber strip 84 assigned to the edge of the screen printing plate 26; the latter is penetrated in FIG. 13 by coil springs 53 which are seated on one end in the plastic strip 82 and on the other end in a web 79 which engages under the rubber strip 84. This is screwed onto the left of the side strips 76 in FIG. 13 and is equipped towards the table with an inclined surface 79 _a parallel to the printing table 74. Those helical springs 53 open a clamping jaw 86 thus created when the pressure in the air bellows 80 has dropped to 0 bar.

In clamp mouth 86 - d. H. between the web 79 and the rubber strip 84 - runs an edge area of the screen printing plate 26 by means of one - partly from the other Sidebar 76 protruding - elastic bead 88 den Printing table 74 is supplied. This elastic edge 88 is generated here is a smoothing effect.

14, the coil springs are missing 53; the plastic strip 82a is optionally domed, to compensate for the deflection of the frame or the Relieve plate edges.

15, 16 indicate assembly aids; 15, the clamping jaw 86 receives an angled and magnetic sheet 90, the register pins 68 _a and - under a shaft 92 - a magnetic tape 94 are assigned. Thanks to this device, the edge area of the template 26 can be better handled.

16 illustrates a suction cup 96 on a vacuum bar 98, one of the edges of the screen printing plate 26 seated, elastic film 27 as a guide or Lifting aid sits on.

Protection is provided for the assembly aids of FIGS. 15, 16 coveted.

Claims (25)

1. Printing apparatus with a flexible screen printing mould (26) made of woven plastic fabric (10) in a printing frame (24) in which the screen printing mould (26) can be fixed and tensioned in two parallel regions crossing the direction of movement of a slidable squeegee (32) or the like tool for the application of printing inks with the interposition of connecting elements on the one hand on one side (34_a, 34_b, 34_c, 34_d, 34_e, 34_f, 78) of the printing frame (24) and on the other hand at a tensioning or moving element (40, 40_b, 40_c, 40_d) slidable in the latter parallel to that side (34_a, 34_b, 34_c, 34_d, 34_e, 34_f, 78) of the frame, characterised in that the screen printing mould (26) is made of a woven metallised plastic fabric (10a) which is provided with a metal envelope layer (18) and the latter is in turn covered by a metal coat (22) carrying an emulsion, wherein the woven plastic fabric is provided with the metal envelope layer from both sides of the fabric and then coated by electroplating, and in that the connecting elements are profiled connecting rails (27, 28, 28_e, 28_f, 44, 82, 82_a, 90) or bearing profiles (54) one of which is connected to the moving element constructed as a tension bar (40, 40_b, 40_c, 40_d).
2. Printing apparatus according to claim 1, characterised in that the tension bar (40, 40_b, 40_c, 40_d) within the printing frame (24) is connected to one of its frame sides (34) with the interposition of energy storing elements (42).
3. Printing apparatus according to claim 1 or 2, characterised in that the distance from the tension bar (40, 40_b, 40_c, 40_d) to its frame side (34) in the tensioning position is pneumatically or hydraulically adjustable.
4. Printing apparatus according to any of claims 1 to 3, characterised by a connecting rail (28) cross-sectionally angled approximately in an S shape, of which the end protruding arms (29) in the tensioning position rest firstly on a lower edge (38) of the frame side (34_a, 34_c) or of the tension bar (40, 40_c) and secondly on a shoulder in the undercut interior (36) of the hollow frame side or of the hollow tension bar.
5. Printing apparatus according to any of claims 1 to 4, characterised by a connecting rail (28) cross-sectionally angled approximately in an S shape, of which the end protruding arms (29) in the tensioning position rest on a supporting surface (48) of a tensioning shaft (50) running in the interior (36) of the hollow frame side (34_c) or of the hollow tension bar (40_c).
6. Printing apparatus according to any of claims 1 to 3, characterised in that the connecting rail (44) is a hook rail which is at an angle to the plane of the screen printing plate (26) and which can be inserted in a sloping groove (66) of the frame side (34_b) or of the tension bar (40_c).
7. Printing apparatus according to any of claims 1 to 3, characterised in that the connecting rail (28_e) comprises a protruding arm (29_a) which is bent at an angle (w) out of the plane of the screen printing plate (26) and which can be inserted in a sloping slot (60) inclined at the same angle in the frame side (34_e) or the tension bar (40).
8. Printing apparatus according to any of claims 1 to 3, characterised in that the screen printing plate (26) comprises at each of two parallel edges a piping bead (58) which is laid in a bearing profile (54) as a connecting element.
9. Printing apparatus according to any of claims 6 to 8, characterised in that the connecting rail (28_c, 44) or the bearing profile (54) is held in the tensioning position by an energy storing element (52), wherein if occasion arises the energy storing element (52) forms part of a clamp piece (62) of the frame side (34_b, 34_d, 34_e) or of the tension bar (40_b, 40_d).
10. Printing apparatus according to any of claims 1 to 3, characterised in that the connecting rail (28_f) has fitting or tensioning pins (68) of the frame side (34_f) passing through it and is held by a pressure bar (70) on a supporting surface (72) of the frame side.
11. Printing apparatus according to any of claims 1 to 3, characterised in that in an open hollow profile (78) with sloping groove (66) in the latter is provided a profile (80) of variable cross-section, in particular air bellows, and associated with it towards the groove opening is at least one rail (82, 82_a) which adjoins a resilient strip (84) which if occasion arises is associated with the screen printing place (26).
12. Printing apparatus according co claim 11, characterised in that opposite the rail (82, 82_c), forming a clamp opening (86), is a web (79) which overlaps it and which is connected to the hollow profile (78), wherein if occasion arises energy storing elements (53) pass through the clamp opening.
13. Printing apparatus according to claim 11 or 12.
    characterised in that a resilient bead (88) or the like resilient edge projects from the hollow profile (78) as a stop for the screen printing plate (26), and/or in that the web (79) and/or the resilient bead is/are mounted on a side rail (76) of the hollow profile (78).
14. Printing apparatus according to any of claims 11 to 13, characterised in that the resilient strip (84) is rigidly associated with the rail (82, 82_a) and in a fixing state of the screen printing plate (26) cooperates in clamping relationship with an edge region of the screen printing plate, wherein the edge region if occasion arises is itself opposite a pressure region of the screen printing plate without reinforcements or the like connecting means.
15. Printing apparatus according to any of claims 1 to 3, characterised in that in an open hollow profile (78) with sloping groove (66) in the latter is provided a profile (80) of variable cross-section, in particular air bellows, and associated with it towards the groove opening are fitting pins (68_a) as well as a magnetic band (94) for receiving an angled and magnetic plate (90) located at the edge region of the stencil (26).
16. Screen printing mould with screen printing fabric (10) made of intersecting plastic threads (12, 14) as the carrier of a coating consisting of an emulsion for a printing apparatus according to one or more of claims 1 to 15, characterised in that the plastic threads (12, 14) are coated with an envelope layer (18) which is applied by vapour deposition, plasma spraying or sputtering and consists of at least one metallic material and which is in turn covered by a metal coat (22) carrying the emulsion and produced by electroplating.
17. Screen printing mould according to claim 16, characterised in that the metallic material is applied to the screen printing fabric (10) on both sides thereof by spraying, vapour deposition or sputtering, repeatedly if occasion arises.
18. Screen printing mould according to claim 16 or 17, characterised in that the envelope layer (18) contains gold, silver, nickel or copper in as pure a form as possible.
19. Screen printing mould according to claim 16 or 17, characterised in that the envelope layer (18) contains gold. silver. nickel, copper, steel and/or a light metal, in particular aluminium, as alloy component(s).
20. Screen printing mould according to any of claims 16 to 19, characterised by a layer thickness (b) of the envelope layer (18) of between 5 and over 200 nanometres, in particular between approximately 50 and 200 nanometres, and/or by a surface resistance of the envelope layer (18) from approximately 0.2 ohms/2 to over 200 ohms/2.
21. Screen printing mould according to any of claims 16 to 20, characterised in that the metal coat (22) of the envelope layer (18), which is produced by electroplating, has a layer thickness (e) from approximately 2 µm to over 20 µm.
22. Screen printing mould according to claim 16 or 21, characterised in that the metal coat (22) contains nickel, preferably consists of nickel.
23. Screen printing mould according to any of claims 16 to 22, characterised in that the emulsion which forms a coating on the metal coat (22) is covered by a protective film.
24. Screen printing mould according to one or more of claims 16 to 23, characterised in that screen printing plates (26) of predetermined format size are cut from the woven metallised plastic fabric (10_c).
25. Screen printing mould according to claim 24, characterised in that the screen printing plate (26) is provided at two opposed edges with connecting elements (28, 28_e, 28_f) for fixing to a printing frame (24) and/or the connecting element for one edge of the screen printing plate (26) is a profiled connecting rail (28, 28_e, 28_f).

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