EP2879882A2

EP2879882A2 - Flat screen material and screen

Info

Publication number: EP2879882A2
Application number: EP13728975.7A
Authority: EP
Inventors: Heinz Brocker; Hans-Rudolf Frick
Original assignee: Gallus Ferd Rueesch AG
Current assignee: Gallus Ferd Rueesch AG
Priority date: 2012-06-14
Filing date: 2013-06-12
Publication date: 2015-06-10
Anticipated expiration: 2033-06-12
Also published as: CN104364088B; WO2013185916A3; WO2013185916A2; DK2879882T3; ES2711556T3; DE102012011901A1; US9333740B2; JP6157604B2; CN104364088A; JP2015527215A; EP2879882B1; US20150096451A1

Abstract

The invention relates to a flat screen material (1) for use in screen printing, having strands (5, 5.1, 5.2) forming a woven screen structure, said strands being arranged at an angle to each other and crossing at intersection points (10), wherein at said intersection points the strands (5, 5.1, 5.2) form undercuts (11) and otherwise form a screen structure having openings and, at least at the surfaces thereof, consist of metal (3) which was deposited on the strands (5, 5.1, 5.2) in a galvanising process. According to the invention, in the region of the intersection points of the strands (5, 5.1, 5.2), the undercuts (11) thereof have at least in some cases a filling (12) of the metal applied during the galvanising process. This filling can form in particular an inner edge-transition with a rounding (12.1). The fillings improve the properties of the screen material in particular in respect of stability, flow-through and cleaning options. The invention also relates to a screen (4) for rotary screen printing made of such a flat screen material (1).

Description

The invention relates to a screen material with the above-mentioned features of

Claim 1 and a sieve with the preamble features of claim 11.

Background Art The industrial application of fabrics and fabrics is known in various fields.

When used in the field of filtration, the square mesh is the usual embodiment. For the printing application, this mesh has been adopted. With the available photo layers and well-known coating methods, a reasonable image resolution can only be achieved with a large number of "supports." Therefore, increasingly high mesh fabrics are used.

When electronic printing as thin as possible screens or fabric are used with the thinnest possible wire to ensure a good flow of pastes and order

to provide the finest possible picture motifs.

The solar cell coating requires a high paste application and a precise and fine image resolution. For example, for applying printed conductors as current fingers with the smallest possible coverage of the solar cells, in order to ensure a high efficiency of the solar cells.

The screens or fabrics used for electronic printing are very expensive and delicate to process, making them unsuitable for the production of screen printing plates for rotary screen printing. The lack of suitability is also due to the fact that the screen fabric in the rotary screen in one direction, namely the

Cylinder longitudinal axis can be stretched, in flat screen printing, however, however, in two dimensions. In rotary screen printing, the color is transported through the screen by the hydrodynamic pressure generated by the rotation of the screen and by the squeegee in front of the squeegee. By design, only open or semi-open

Use squeegee systems, so that the dynamic pressure is influenced by many factors such as viscosity, filling quantity and rotational speed. By increasing the speed of rotation or the amount of ink, the hydrodynamic pressure can be easily increased.

Such a rotary screen printing unit is described for example in WO 99/19146 AI.

As basic structures for screen materials are known in the art

Stainless steel mesh used with linen weave. The ratio of sieve opening, contact area and fabric thickness has proven to be suitable. The thickness of the structure, ie the fabric thickness (initial dimension before calendering) corresponds approximately to twice the wire thickness. The basic structure is processed in a further step in a calendering process, also referred to as a calendering process, and thus adjusted to the desired

Raw fabric thickness brought. Also, a higher smoothness of the screen and thus a lower screen and blade wear is achieved. In the subsequent

Vernickelungsvorgang the fabric for the purpose of a higher wear resistance is generally uniform, ie symmetrical to the axis of the fabric threads, reinforced and increases the support points in the region of the crossing points. However, methods are also known for selective deposition only in one direction, perpendicular to the surface of the tissue. Thus, according to EP 0049022 AI by adaptation of

Flow rate and the addition of chemical additives reaches a targeted metal deposition.

A complete process for producing such screen materials is described, for example, in EP 0 182 195 A2.

It is known from the prior art that stainless steel fabrics, e.g. for the

Rotary screen printing are metallized by means of galvanic processes.

The state of the art for nickel plating is that preferably sulphamate nickel baths or chemical nickel processes (external powerless) are used. Of the The advantage of this method is a uniform geometric layer distribution in all spatial planes. The disadvantage of this method is that at the crossing point a so-called angle weakness, hereinafter also referred to as an undercut, arises. The undercut has the property that the flow behavior, eg at

Cleaning processes and color in the printing, and also the stability of the metallized fabric are adversely affected.

It is also known that multiple nickel layers are deposited as corrosion protection and / or for decorative purposes with Watt's nickel sulphate electrolytes. These methods can be applied in a wide range of applications for refining various components in different industries.

The Watt's nickel sulphate baths are mixed with a wide variety of, preferably organic, additives. The additives are subdivided into gloss additives (so-called glossy carrier) first (primary) and second (secondary) class. Primary glossy supports, which incidentally may also have properties of second-class luster carriers, are used to achieve homogeneous metal deposition with a specific base luster over as wide a current density range as possible. Secondary glosses have a large influence on the leveling and gloss level.

Furthermore, the first and second class gloss supports have, in combination, other effects on the deposited nickel layer: gloss, ductility, hardness,

Leveling behavior and electrochemical potential of the deposited layers with each other.

Mixtures of organic additives available on the market must meet a variety of technical requirements. These concoctions and nickel baths are in the

Essentially tailored to the metallisation of general cargo in drum systems. For the nickel plating of tissue, these baths can only be used to a limited extent in reel to reel systems (roll-to-roll). A common feature of metallization is that the surface to be refined faces the anode during the metallization process (eg in drum systems by turning).

This, in combination with the addition of additives, allows a uniform

Layer distribution. In a reel to reel system, this could theoretically be achieved by a tape guide between two anodes. However, tissue, especially microfibre tissue, has the

Characteristic to expand extremely fast due to power supply and its low mass, which leads to wave formation and internal stresses. In addition, the mixtures listed above are tuned so that either an undercut in the

Crossing point remains or the mesh openings too close.

In order to ensure the stability of the screening material, a close-meshed structure with many support points is chosen. These are known from the prior art

Screening materials and screens have the following disadvantages:

In the crossing points of the fabric threads are angle weaknesses, ie undercuts. In other words, the stability of woven fabrics is limited by the notch effect in the region of the crossing points of the fabric threads.

An enhanced coating by the well-known galvanic

Coating process is not a solution, since the openings of the fabric grow and it can come when used by screen printing for clogging of the openings by paint particles. This will affect the print quality.

Task The object of the present invention is therefore to provide a sieve material and a sieve which do not have the disadvantages of the sieve materials and sieves known from the prior art and are particularly suitable for rotary screen printing. The screen materials, in particular steel mesh, should have a higher stability and a longer service life for use in rotary screen printing.

This object is achieved by a sieve material with the features of claim 1 and by a sieve with the features of claim 1. These are particularly advantageous since They meet the specific requirements of rotary screen printing and have a greater stability compared to conventional screen materials and screens. The flat screen material according to the invention is used in screen printing, in particular in rotary screen printing. The screen material has skewed and intersecting strands which form a woven screen structure, the invention being independent of the weave and the invention

Mesh shape. At the points of intersection, the strands form undercuts, wherein undercuts mean the inner edges of adjacent surfaces of the intersecting strands, for example of warp threads and weft threads. These thus have an angular weakness, which is also referred to as inner edge weakness. The strands are arranged so that a screen structure is formed with openings. Throughout their surfaces, the strands have a coating of approximately constant thickness of metal, particularly nickel, which has been deposited on the strands in a plating process. According to the invention, the areal sieve material is designed in such a way that, in the region of crossing points of the strands, their undercuts, in addition to the coating, at least partially have a filling of the metal applied in a plating process. In other words, by the

Galvanization process, the undercuts were reduced or eliminated by additional metal was deposited specifically in the area of the undercuts. This creates a surface without sharp edges and chamfers.

Such a flat screen material has the advantage that through the metallic

Fillings when using the screen material for screen printing flow resistance and turbulence are reduced, resulting in better flow behavior of the paint. Furthermore, no ink can dry in the undercut. He will too

Cleaning process further simplified, since a direct flow with

Cleaning fluid is enabled, which contributes to a shorter cleaning time and a lower consumption of cleaning fluid. Another advantage is the increased stability of the flat screen material, since the notch effect of the undercuts is reduced by the metallic filling. In a particularly advantageous and therefore preferred development of the screening material according to the invention, a respective filling forms an inner edge transition with a rounding. The metal filling is thus designed so that there are no sharp edges or chamfers in the area of the undercuts. It is particularly advantageous if the fillings have a radius of at least 1 μm or at least one tenth of the mean radius of the strands (mean value of radius warp thread and radius weft thread). This ensures that in screen-printing applications, the ink can easily flow through the screen material and there are no significant deposits in the area of the undercuts, and the screen material is easy to clean, with high stability.

In a first embodiment of the flat screen material according to the invention, a curve along the surface of the screen material - in a sectional plane perpendicular to the screen material and viewed through one of the strands - describes a smooth curve. A smooth curve is understood to mean a smooth curve in the mathematical sense, i. a curve that is continuous and differentiable, ie a curve without corners or abrupt turns.

In a second embodiment of the flat screen material according to the invention, a curve along the surface of the screen material - in a sectional plane parallel to the screen material and viewed through all the strands - describes a smooth curve. A smooth curve is understood to mean a smooth curve in the mathematical sense, i. a curve which is continuous and differentiable, i. a curve without corners or abrupt twists. For the first variant, the undercuts at the top and / or at the bottom of the screen material each have a metallic padding. For the second variant, however, the undercuts in the plane of the screen material each have a metallic filling. In an advantageous development, both

Variants combined with each other, so that a particularly stable and flow-optimized flat screen material is formed.

In an advantageous embodiment of the flat screen material with smooth curves between two crossing points, the curve along the surface of the screen material has two Turning points on, with the turning points limit the replenishment. Under a

Turning point is understood as a turning point in the mathematical sense, i. a point on the surface curve in which a sign change of the first derivative takes place. The turning points may in particular have a distance from each other of at least 1 μπι and a maximum of a distance corresponding to the pitch. By division, the distance between the center axes of two adjacent, mutually parallel strands is called. In particular, however, the turning points are 10 to 20 μιη spaced apart. Refills that fall into this area are on the one hand

On the other hand, it is easy to manufacture and meet the expectations of higher stability and better flow properties of the flat screen material.

In an alternative embodiment for filling with rounding becomes a

provided parabolic fill, which itself has an undercut. In the case of the parabolic filling, the sieve material in the region of a respective undercut is filled up to a particularly high degree and reinforced.

In a further alternative embodiment, the fillings are designed in such a way that the surfaces of the fillings on the surface and / or on the underside of the sieve material are in each case almost in one plane. In other words, the metal fill causes the strands to be completely embedded in the metallic padding.

In development of this or the previously described screen materials has the

Sieve material a screen structure diluted in a calendering process with calendered surfaces. A calendering process, also referred to as a calendering process, is understood to mean a process which generally rolls and which causes a flattening of the sieve structure.

Such a calendering process is described for example in DE 691 08 040 T2. The flat screen material is formed by a tissue, for. B. by a

Plastic fabric or a metal wire mesh. The structure has the form of so-called meshes, e.g. B. of rectangular mesh or square mesh. The strands are made of metal at their surfaces, with nickel being particularly advantageous and therefore preferred. The metal was deposited on the strands in a galvanization process. For the production of the screen material according to the invention described above, a fabric structure is preferably metallized with one or more, in particular nickel-containing layers of only one electrolyte bath, wherein the electrolyte bath for

Reinforcement of crossing points targeted organic additives can be added. The formation of the nickel layer is further influenced by the tissue is moved past the non-anode side of the fabric on non-conductive bodies, ie insulators, which change the field and thus influence the nickel deposition. During the passage, the fabric structure rests on the insulator. Also, the anodes can be arranged so that they have a different distance to the tissue over their extent. Thus, the nickel layer distribution in the

Crossing points on the front and back of the fabric to be optimized. As anodes, depolarized pure nickel plates or nickel pellets can be used in baskets.

By means of such a method and the combination of overlying

Nickel plating process, specific dosage of brighteners first and second class and targeted flow through the electrolyte, the current lines of the electric field can be influenced so that specifically more nickel can be deposited on the anode-facing side of the fabric in the crossing points. As a result, it can furthermore be achieved that a single strand of the fabric is nickel-plated eccentrically, with a stronger coating also taking place here on the side facing away from the anode.

With ideal coordination of all components, the coating can be carried out in a single process step. This is especially true when applying thin ones

Nickel layers of a few micrometers advantageous.

If thicker layers have to be deposited over 2 μm, then it is advantageous Subdivide layer order into several process steps, but can be dispensed with different electrolyte baths.

Between the deposition of the individual nickel layers, the tissue

be cleaned between.

The invention also relates to a screen for rotary screen printing, which is made of a flat screen material, as described above, and wherein the screen has the shape of a cylindrical sleeve.

In an advantageous embodiment of the invention sieve is the area

Sieve material on one side with a polymer layer, in particular with a

Photopolymer layer provided so that an imaging is made possible by methods known in the art.

The invention described and the described advantageous developments of the invention also make advantageous in any combination with each other

Further developments of the invention.

With regard to further advantages and constructive and functional aspects of advantageous embodiments of the invention, reference is made to the dependent claims and the description of embodiments with reference to the accompanying drawings.

embodiment

The invention will be explained in more detail with reference to an embodiment. It show in a schematic representation

1 shows a sieve according to the invention

Fig. 2a a screen material before nickel plating

2b shows a screen material after nickel plating

Fig. 3a is a sectional view with a section perpendicular to the screen material

Fig. 3b shows a detailed view of Fig. 3 a

Fig. 3 c is a detail of Fig. 3 a before filling Fig. 4a Alternative fillings of the undercuts

Fig. 4b fillings of the undercuts of a calendered fabric

Fig. 5 is a sectional view with a section in the plane of the screen material

Fig. 6 is a screen for rotary screen printing

Corresponding elements and components are the same in the figures

Provided with reference numerals.

In the following, a method for producing the screen material 1 according to the invention and, by way of example, a required bath composition will be described by way of example. It is assumed that in the galvanization nickel 3 on the

Fabric structure 5 is to be applied.

The basis for the nickel plating may be a Watt nickel electrolytic bath to which preferably primary and secondary brighteners are added:

Nickel 60 - 90 g / 1

Chloride 12-45 g / l

Boric acid 30 - 50 g / 1

Bath temperature 45 - 70 ° C,

pH value 3.5 to 4.8,

For deposition, it is preferable to add brightener additives, so-called

Secondary luster, such as Butynediol derivatives, quaternary pyridinium derivatives, propargyl alcohol, propynol propoxylates, especially butynediol, and primary brighteners, e.g. Benzenesulfonic acids, alkylsulfonic acids, alylsulfonic acids, sulfonimides,

Sulfonamides or benzoic acid sulfimide.

Secondary brighteners are used in this application for the defined reinforcement of the crossing points 10, these being added depending on the desired reinforcement in a content of 0 to 0.15 g / 1, primary brightener between 0 and 8 g / 1. The fabric structure 5, which is pretreated as usual in electroplating, is nickel-plated with the bath described above.

The fabric 5 is transported in the nickel bath via an electrical non-conductive support surface.

The electrically non-conductive support surface can be provided transversely to the transport direction of the fabric 5 with segments which are also filled with electrolyte during operation and ensure a permanent exchange of electrolyte.

On the resting surface is by non-existent electrolyte the

Nickel deposition 3 impeded.

By appropriate addition of secondary gloss carrier concentrates the

Metal deposition 3 additionally targeted in the crossing points 10th

In the segmented zone a deposition also takes place on the

Tissue back held. By a clever distribution of the segments to the resting surface, combined with the corresponding amount of secondary gloss carrier, the nickel deposition 3 can be distributed over the crossing points or the entire back.

Due to an ideal electrolyte flow between the anode and the tissue structure as the cathode, the deposition rate on the tissue is reduced on the anode side. It has been shown in this arrangement that increased deposition on the

Anodenabgewandten side can be done.

An ideal anode distance is between 1 cm and 40 cm to the cathode. This distance is advantageous in that the tissue 5 can still be sufficiently strongly flowed with fresh electrolyte, the electrical voltage losses through the increased

Anode distance, however, remain at a tolerable level.

The nickel plating can basically take place in a single nickel cell. However, it is also conceivable to arrange several nickel cells one behind the other.

Fig. 1 shows an inventive sheet-like screen material 1, which is provided on one side with a photo-polymer coating 2 (direct template). In a not shown Alternatively embodiment, an already imaged film can be applied to the screen structure 1 (indirect template). The nickel-plated planar screen material 1 is constructed from a fabric. In Fig. 2a, a sheet-like screen material 1 is shown, which is formed from interwoven strands 5. The strands 5 are arranged at right angles to each other and at a distance, so that openings 6 are formed in the flat screen material 1. The region in which the strands 5 arranged at right angles to one another meet or push against one another is referred to as the intersection point 10. By a

Metal coating 3, z. As nickel, which is applied in a galvanic process on the strands 5, the strands 5 are connected to each other in the crossing points 10. Since the metal coating 3 is applied substantially evenly to the surface of the strands 5, where the surfaces of the strands 5 meet, what are known as undercuts 1 1. In other words, the adjoining surfaces of the strands 5, for example of warp yarns 5.1 and

Weft 5.2, form inside edges in their lines of contact. This has one

Inner edge weakness, also referred to as an angle weakness, the result, which has a negative impact on stability, flow properties and cleaning ability of the flat

Sieve material 1 affects.

In Fig. 2a, a Cartesian coordinate system xyz is given, wherein the flat screen material 1 is in the xy plane. The z-axis is oriented orthogonal to this plane. FIG. 2b shows the flat screen material 1 from FIG. 2a. In this case, the undercuts 11 were provided in the intersection points 10 according to the invention by selective deposition each with a padding 12. The targeted deposition can be carried out in particular in the context of the galvanic production of the metal coating 3. By filling 12 of the undercuts 1 1, the properties of the flat screen material 1 in particular with regard to stability, color flow and cleaning ability are significantly improved. FIG. 3a shows a section through the flat screen material 1 in the xz plane or in the yz plane: the warp threads 5.1 and weft threads 5.2 are each provided with a

Metal coating 3 provided. As indicated in Fig. 3c, the layer thickness of the metal coating a, b, c on the upper surface (upper side 28) and the lower surface (lower side 29) of warp yarn 5.1 and weft yarn 5.2 may be uniform or different. By different layer thicknesses a, b, c of the metal coating 3, the properties of the flat screen material 1 can be influenced. Also, the diameters 26, 27 of warp yarns 5.1 and weft yarn 5.2 can be either of the same size or of different sizes. Here too, influence can be exerted on the weave structure and thus on the properties of the flat screen material 1. As further geometric variables, in FIG. 3 a the neutral fiber 20 is defined by the wire longitudinal section and the division 21, which defines the distance between two center axes of strands 5 (FIG. 5.1). At the points of intersection 10, the undercuts 1 1, which can still be seen in FIG. 3 c, have been provided with a filling 12 according to FIG. 3 a by selective deposition. This results in an inner edge transition with rounding 12.1, wherein the rounding has a radius 25. Inside edges, chamfers, incisions or undercuts were removed and the

Surface has a smooth transition between the strands 5. 3 b, the fillings 12 of the undercuts 1 1 can be seen more clearly: if the curve along the surface of the screen material 1 is considered in the embodiment according to FIG. 3 b, then two points of inflection are in the region of a respective filling 12 22, which are turning points in mathematical understanding. Stated another way: between the turning points 22 there is a filling 12 of the undercut 11, outside the turning points 22, however, the warp thread is 5.1 or the weft 5.2 with the usual metal coating 3 of layer thickness a, b, c provided. The filling 12 produced by targeted deposition has - approximately in the middle between the two turning points 22 - the largest filling strength 24, which is measured between the surface of the filling 12 and the theoretical vertex of the undercut 11. FIG. 4 a shows alternative galvanic coatings i, ii, iii, iv. According to alternative i, the padding 12 is parabolic. Thus, the Auffüllstärke the padding 12 in the region of the original undercut 1 1 is particularly large. However, the padding 12 is designed such that through the filling further has an undercut, which is formed by the filling of an inner edge.

According to the alternative ii, a particularly strong galvanic coating was applied to fill 12 of the undercut 1 1. The padding 12 is so extensive that the surface of the padding 12 lies in a plane 30 and the warp threads 5.1 and the weft threads 5.2 completely in the metal coating 3, 12 are embedded. As a result, a flat screen material 1 is created, which has a flat surface which lies in the plane 30.

Also according to the variant iii, the undercut 1 1 was provided with a particularly strong padding 12. As already described with reference to FIG. 3a, the padding 12 has an inner edge transition with rounding 12.1. In contrast to

Embodiment according to FIG. 3a, however, the rounding has a particularly large radius. The coating alternative iv can be used alternatively or in combination with the previously described coating alternatives. In this case, in the region of a respective warp thread 5.1 or weft thread 5.2, a reinforced metal coating 3 takes place, so that the metal coating 3 has a particularly high layer thickness on one side, that is, the coating is applied eccentrically.

In Fig. 4b a strongly calendered sheet sieve material 1 is shown. Before the fabric of warp yarns 5.1 and weft yarns 5.2 with the metal coating 3, the fabric was rolled and thus flattened. This calendered surfaces 5.3, ie flattened areas were created. Since even under a calendered fabric after the metal coating 3 undercuts 1 1 in the region of the crossing points 10, the alternatives described above for the galvanic coating can be used equally here. As shown, the undercuts 1 1 leave on the bottom 29 of the sheet material 1 in its original state, while at the top 28 of the sheet material 1, the undercuts 1 1 were each provided with a padding 12. 5 shows a section through the flat screen material 1 in the xy plane, ie in the plane of the flat screen material 1. As shown in the upper half of FIG. 5, the flat screen material 1 has warp threads 5.1 in the region of the crossing points 10 and weft 5.2 also undercuts 11. These undercuts 1 1, as described above, and shown in the lower part of Fig. 5, also with fillings 12, ie targeted deposits are provided. Again, the fillings 12 may have an inner edge transition with rounding 12.1, wherein the padding 12 may be limited by two turning points 22 and may have a radius 25. In Fig. 6, a screen 4 is indicated with a flat screen material 1 in a cylindrical sleeve shape for rotary screen printing. The screen material 1 is held by unspecified tails in its cylindrical shape. Inside the screen 4 is a - not visible here - squeegee to squeeze paint through the screen material. The orientation of the doctor blade may be parallel to the axis of rotation of the screen 4. The rotation U of the screen 4 during printing is indicated by a double arrow.

LIST OF REFERENCE NUMBERS

1 flat screen material

2 polymer coating

3 metal coating (e.g., nickel)

4 sieve in cylindrical sleeve shape

5 strand

5.1 warp thread

5.2 weft

5.3 calendered area

6 opening

10 crossing point

11 undercut

12 replenishment (targeted deposition)

12.1 Inner edge transition with rounding

20 neutral fiber by wire cut

21 division

22 turning point

23 distance turning points

24 fill level

25 radius

26 radius warp thread

27 radius weft

28 top

29 bottom

30 plane i, ii, iii, iv Alternative galvanic coatings x, y, z Axes of a coordinate system a, b, c Layer thicknesses of the metal coating

U rotation of the sieve

Claims

claims

1. Flat screen material (1) for use in screen printing, in particular in

Rotary screen printing, with a woven screen structure forming, at an angle to each other and arranged in crossing points (10) crossing strands (5, 5.1, 5.2), wherein the strands (5, 5.1, 5.2) there form undercuts (11), and wherein the strands a Form sieve structure with openings and the strands (5, 5.1, 5.2) have on their surfaces a coating of approximately constant thickness of metal (3), in particular nickel, which was deposited in a galvanization process on the strands (5, 5.1, 5.2) .

characterized,

that in the region of crossing points of the strands (5, 5.1, 5.2) whose

Undercuts (11) in addition to the coating at least partially in the

Galvanisierungsprozess applied filling (12) from the metal, in particular, the respective filling (12) on its surface has no sharp edges and chamfers.

2. Sheet material according to claim 1,

characterized,

a respective filling (12) forms an inner edge transition with rounding (12.1).

3. Flat screen material according to one of the preceding claims,

characterized,

the filling (12) has a radius (25) of at least 1 μm or of 1/10 of the mean radius (26, 27) of the strands (5, 5.1, 5.2).

4. Flat screen material according to one of the preceding claims,

characterized,

that a curve along the surface of the screen material (1) - in one

Section plane (xz, yz) perpendicular to the sieve material (1) and through one of the strands (5, 5.1, 5.2) - describes a smooth curve.

5. Sheet material according to one of the preceding claims,

characterized,

that a curve along the surface of the screen material (1) - in one

Section plane (xy) parallel to the sieve material (1) and considered by all strands (5, 5.1, 5.2) - describes a smooth curve.

6. Sheet material according to one of claims 4 or 5,

characterized,

in that the curve has two points of inflection (22) along the surface of the screen material (1) between two points of intersection (10), the points of inflection (22) delimiting the filling (12).

7. Flat screen material according to claim 6,

characterized,

that the turning points (22) have a distance (23) from each other of at least 1 μιη and at most the pitch (21), but in particular a distance (23) of 10 to 20 μηι.

8. Sheet material according to one of the preceding claims,

characterized,

the undercuts (11) each have a padding (12) on the upper side (28) and / or on the underside (29) of the screen material (1) and / or in the plane (xy) of the screen material (1).

9. Flat screen material according to claim 1,

characterized,

that the padding (12) is parabolic and the padding (12) each has an undercut (i).

10. Sheet material according to one of the preceding claims,

characterized,

in that the surfaces of the filling (12) on the upper side (28) and / or on the underside (29) of the screen material (1) each lie almost in one plane (ii) (ii), and / or that the screen material (1 ) has a screen structure (1) diluted in a calendering process.

11. screen (4) for rotary screen printing from a flat screen material (1) according to at least one of claims 1 to 10, wherein the screen has the shape of a cylindrical sleeve, and the flat screen material (1) in particular on one side with a polymer layer (2) coated, eg with a

Photopolymer layer.