EP1690981B1 - Method for creating a topographical pattern on or in a papermaking fabric - Google Patents

Abstract

Producing a topographic pattern on or in a paper machine cover comprises producing a topographical polymer pattern by means of a rotary screen. An independent claim is also included for a paper machine cover comprising topographical polymer pattern, preferably produced by means of a rotary screen, as an external or internal feature.

Description

The invention relates to a method for producing a topographic pattern on or in a papermachine fabric according to the preamble of claim 1.

The use of rotary screen printing in the textile industry is well known. Typical examples of rotary screen printing are in the Patents US 2511511 (Murphy) and US 3,420,167 (Van der Winden). Restrictions in the design and manufacture of rotary screens determine, for example, which string widths can be processed.

Rotary screens, supplied by Stork NV, are usually located in the Fig. 1 resulting configuration. End or end rings 10, which have a larger diameter than the wires 12 themselves, provide the means by which the wire 12 is secured and rotated on the machine. During printing, the fabric must be in a width which allows it to pass between the two end rings 10 and which allows it to make direct contact with the wire 12. The actual application width 14 of a rotary screen is therefore always narrower than its entire "machine width" dimension 16.

Stork NV supplies rotary screens in the following machine widths: 1410, 1750, 1980, 2650, 3050, 3500 and 3800 mm.

Saxon Screens is another manufacturer of rotary screens, with the maximum available width of these screens being 2080 mm.

However, fabrics used in different sections of a paper machine can now be up to 10 m wide. Since this is the case, standard rotary screens can not be used to transfer topographical features across the entire width of the papermachine clothing because of the screen design limitations as described above.

The production of topographical fabrics for the production of jewelry paper products is known. For example, the teaches US 6203663 (Kamps) teaches a method of applying a pattern to a forming fabric using either embroidering, stencil printing, printing or weaving techniques. The latter technique of weaving does not allow for the creation of complex topographical patterns and is more suitable for "dot patterning" where raised fabric bumps are used to create small holes in the paper product. While complex topographical patterns can be achieved by using embroidery techniques, the pattern is prone to deteriorate by the effect of abrasion. Stencil printing has similar problems to those associated with rotary screen printing in relation to the limited screen widths. Therefore, in order to transfer topographic features to wide paper machine clothing by this process, it would be necessary to print the fabric section by section across its entire width. The inherent problems with this method are that on the one hand it is extremely time consuming and on the other hand it is necessary to position the stencil screen relative to a previously printed section so that the topographic pattern is aligned and adjusted accordingly.

US 452980 (Trokhan) teaches a method of making a woven fabric having a UV-cured polymer pattern network with deflection channels. The pattern mesh and the deflection channels extend across the entire width of the papermaking screen and are referred to as endless because it is essentially an unbroken net-like pattern. However, due to process limitations, the UV-cured pattern mesh must be applied to the screen in a batch fashion or section by section. In addition, the application of a UV-cured portion requires a number of different and defined steps which must be performed consecutively. This particular complex process has the disadvantage that it is both time consuming and requires great attention in aligning and aligning the topographical pattern during the patching application.

From the US 4,300,982 Furthermore, a press felt is known which has a pattern applied with a rotating screen.

The US 2004/0126544 shows a papermachine fabric in which was applied to the crossing points of the longitudinal and transverse threads of polymer material to increase the abrasion resistance, for example by means of a screen printing process.

The invention has for its object to provide a simple and fast method for producing a durable pattern structure, can be made with the paper improver quality. With the invention, it should be possible to apply the pattern structure over the entire width of the paper machine clothing.

With regard to the method, this object is achieved by the characterizing features of claim 1. According to the invention, the rotary screen extends only over a partial width of a carrier structure of the clothing. To form the topographic polymer pattern on a support structure, the rotary screen is moved relative to the support structure, whereby, with respect to the width of the support structure, a plurality of juxtaposed topographic pattern sections of polymer material are formed on the support structure. The movement of the rotary screen relative to the support structure takes place here in such a way that the offset between adjacent pattern sections, at least in the plane of the support structure, is 0.1 mm or less.

The polymer is in this case fed to the paper machine clothing via the rotary screen.

Preferred embodiments of the erfihdungsgemäßen method will become apparent from the dependent claims and the following description.

The invention thus provides a topographical pattern structure which can be applied simply and precisely by means of a rotary screen application head on a papermachine fabric. The application process can be either continuous or section by section, but in any case, accurate alignment and alignment of the topographic pattern is achieved regardless of screen width.

The invention thus serves the exact application and attachment of topographic polymer patterns on the support structure paper machine clothing. The backing structure may be woven as used for forming and dryer fabrics, or it may be a nonwoven, such as in bonded fabrics or needled felts for press felts.

The support structure serves to support the polymeric topographical pattern. The support structure may have load-receiving function in the papermachine fabric, such as a fabric. Alternatively, the support structure may not have a load-bearing function, such as a nonwoven fabric.

For example, the topographic pattern may take the form of a unique motif or a symmetrical grid of polymer dots. In either case, the polymer is fed to the papermachine fabric by means of a rotary screen having the motif or dot pattern engraved in it. The volume of polymer which is supplied to the papermachine clothing is controlled by the dimensions of the screen motif and also by the polymer pumping system. Polymer penetration into the fabric is determined by rearward force generated by the pump.

The topographical pattern may be used as an outer or inner feature of the papermachine fabric. As an external feature, the topographic pattern forms part of the paper-contacting side of the fabric. In contrast, the topographic pattern is applied as an intrinsic feature on the surface of a support structure, such as a nonwoven, disposed in a press felt. Therefore, the pattern will be within the composite structure of the press felt and thus affect paper formation during wet pressing.

The invention provides a greater degree of control and reduces the difficulties of other such processes described in the prior art.

• Eine einsetzbare Polymerviskosität von > 70 Pa.s (70 000 cP), vorzugsweise 100 bis 150 Pa.s (100 000 bis 150 000 cP).
• Eine Musterhöhe über der Bespannung von 0,05 mm - 1,0 mm.
• Ein Breite-zu-Höhe-Verhältnis von bis zu 1 : 0,7 (Silikon), 1 : 0,5 (Polyurethan).
• Rotationssiebbreite von bis zu 2 m breit.
• Eine topographische Musterabgleichgenauigkeit bzw. einen Versatz, zumindest in der Ebene der Trägerstruktur, von 0, 1 mm oder weniger.
• Totale topographische Mustersynchronisation in Bezug auf den Bespannungsumfang.
• Das Polymer kann aus Polyurethan, Silikon, Polyharnstoffen oder jeder Verbindung davon bestehen.
• Gewebte Papiermaschinenbespannungen können von jeder Webgestaltung sein und Garne aus jeder Polymerart (Polyester, Polyamid usw.) umfassen.
• Vliespapierherstellungsbespannungen können von jedem Typ (vernadelt, spunbonded, vernetzt usw.) sein und Fasern oder Garne aus jeder Polymerart (Polyester, Polyamid usw.) umfassen.

The invention is characterized by its precise technological control and repeatability and can be defined by one or more of the following features:

• An employable polymer viscosity of> 70 Pa.s (70,000 cP), preferably 100 to 150 Pa.s (100,000 to 150,000 cP).
• A pattern height above the fabric of 0.05 mm - 1.0 mm.
• A width-to-height ratio of up to 1: 0.7 (silicone), 1: 0.5 (polyurethane).
• Rotary screen width of up to 2 m wide.
• A topographic pattern matching accuracy or offset, at least in the plane of the support structure, of 0, 1 mm or less.
• Total topographical pattern synchronization in relation to the amount of clothing.
• The polymer may consist of polyurethane, silicone, polyureas or any compound thereof.
• Woven paper machine clothing can be of any weave design and include yarns of any type of polymer (polyester, polyamide, etc.).
• Nonwoven papermaking fabrics may be of any type (needlepunched, spunbonded, crosslinked, etc.) and may include fibers or yarns of any type of polymer (polyester, polyamide, etc.).

• Im halbfortlaufenden Betrieb muss die erste Stufe einen anfänglichen Abschnitt auf den gesamten Umfang der Bespannung aufbringen. Das Rotationssieb wird dann über eine Position mit einem Index versehen, wo es den zweiten Abschnitt aufbringen wird. Die Steuerung und der Grad der Siebbewegung sind derartig, dass der genaue Musterabgleich in Bezug auf den anfänglichen Abschnitt innerhalb einer Toleranz von 0,1 mm oder weniger auftritt. Der Vorgang setzt sich auf diese Weise fort, bis die gesamte Breite der Papiermaschinenbespannung mit dem topographischen Muster bedeckt ist. Ein zusätzlicher Vorteil des halbfortlaufenden Betriebs besteht darin, dass das Rotationssieb vor dem Abschnittsauftrag gewechselt werden kann. Daher ist es möglich, eine Vielzahl von topographischen Mustern auf einer Papiermaschinenbespannung aufzuweisen.
• In der fortlaufenden Betriebsart wird die gesamte Breite der Papiermaschinenbespannung mit dem topographischen Muster in einem Vorgang bedeckt. Die fortlaufende Betriebsart wird durch langsames Queren des Rotationssiebs relativ zur Bespannung erzielt, so dass das Muster auf eine spiralförmige Weise aufgebracht wird. Die Spiralwinkelbewegung des Siebs wird durch eine Anzahl von miteinander verbundenen Vorgangsparametern bestimmt, welche den Bespannungsumfang, die Bespannungsbreite, die Bespannungsgeschwindigkeit, den Siebumfang, die Siebmu sterteilung und die Siebgeschwindigkeit umfassen. Der hohe Grad an Vorgangssteuerung während des fortlaufenden (Spiral-)Betriebs erlaubt genauen Musterabgleich, welcher nur innerhalb einer Toleranz von 0,1 mm auftreten kann.

An advantage of the system is the ability to select whether the topographic pattern is applied in either semi-continuous (ie, section-by-section) or continuous (spiral) mode. In any way, the polymer is fed continuously to the rotary screen, which in turn transmits it to the fabric.

• In semi-continuous operation, the first stage must apply an initial section to the entire circumference of the clothing. The rotary screen is then indexed over a position where it will apply the second section. The control and the degree of wire movement are such that the accurate pattern matching with respect to the initial portion occurs within a tolerance of 0.1 mm or less. The process continues in this manner until the entire width of the papermachine fabric is covered with the topographical pattern. An additional advantage of semi-continuous operation is that the rotary screen can be changed before the section job. Therefore, it is possible to have a variety of topographical patterns on a papermachine fabric.
• In the continuous mode, the entire width of the paper machine clothing is covered with the topographical pattern in one operation. The continuous mode of operation is achieved by slowly traversing the rotary screen relative to the fabric so that the pattern is applied in a helical fashion. The spiral angle movement of the wire is determined by a number of interconnected process parameters, which the amount of clothing, the clothing width, the clothing speed, the Siebumfang, the Siebmu sterteil and the screen speed include. The high degree of process control during continuous (spiral) operation allows accurate pattern matching, which can only occur within a tolerance of 0.1 mm.

• Bei den fortlaufenden Gestaltungsformen wird die Betonung auf Beibehalten eines netzartigen Musters gelegt.
• Bei den nicht fortlaufenden Gestaltungsformen wird die Betonung auf Beibehalten des Siebteilungsabstands zwischen den Motiven oder Punkten gelegt.

Topographic pattern matching is an important and unique feature of this invention and is essential to meeting quality standards during the papermaking process. Topographic pattern matching affects both continuous and discontinuous motif and point design.

• In the ongoing designs, the emphasis is placed on maintaining a net-like pattern.
• In the non-contiguous designs emphasis is placed on maintaining the screen pitch between motifs or dots.

In the following concrete embodiments or preferred embodiments are reproduced.

1. 1) Eine fortlaufende oder nicht fortlaufende Musteraufbringung auf eine Papiermaschinenbespannung für den Einsatz in der Herstellung von Schmucktissue oder Schmuckpapier.
2. 2) Genauer Abgleich des topographischen Musters, um die Qualität des Schmucktissues oder Schmuckpapiers sicherzustellen und aufrechtzuerhalten.
3. 3) Anwendung auf der Papierseite ein er Formierbespannung, um Wasserzeicheneffekte durch Neuverteilung von Papierfaserausrichtung während der Blattformierung bzw. Blattbildung zu erzeugen.
4. 4) Anwendung auf der Papierseite oder innerhalb einen(s) Pressfilz(es), um Schmuckpapiereffekte während des Nasspressvorgangs zu erzeugen.
5. 5) Anwendung von unterschiedlichen topographischen Mustern auf eine Bespannung, um mehrere Schmuckeffekte in einem Papierprodukt zu erzeugen.

An accurate topographic patterning and pattern matching system as disclosed herein:

1. 1) A continuous or discontinuous pattern application to a papermachine fabric for use in the manufacture of jewelry tissue or jewelry paper.
2. 2) Exact matching of the topographical pattern to ensure and maintain the quality of the jewelry tissue or jewelry paper.
3. 3) Use on paper side a forming fabric to create watermark effects by redistribution of paper fiber orientation during sheet formation.
4. 4) Use on the paper side or inside a press felt (s) to create decorative paper effects during the wet pressing process.
5. 5) Applying different topographical patterns to a fabric to create multiple jewelry effects in a paper product.

Fig. 1

eine herkömmliche Konfiguration eines Rotationssiebes,

Fig. 2

zwei Ausführungsbeispiele der Erfindung mit einem topographischen Muster in Form eines Punktmusters bzw. einem topographischen Muster in Form eines Motivmusters,

Fig. 3

ein Ausführungsbeispiel der Erfindung mit einem topographischen Muster auf der Oberfläche einer gewebten Papiermaschinenbespannung,

Fig. 4

ein Ausführungsbeispiel der Erfindung mit einem topographischen Muster auf der Oberfläche einer gewebten Grundbespannung und in der Struktur eines Nassfilzes,

Fig. 5

ein Ausführungsbeispiel der Erfindung bezüglich des Aufbringens des topographischen Musters durch das halbfortlaufende Verfahren, d.h. Abschnitt für Abschnitt,

Fig. 6

ein Ausführungsbeispiel der Erfindung bezüglich des Aufbringens des topographischen Musters durch das fortlaufende Verfahren, d.h. in Form einer Spirale,

Fig. 7

ein Ausführungsbeispiel der Erfindung für eine fortlaufende Gestaltungsform in Draufsicht auf die Ebene einer Trägerstruktur und

Fig. 8

ein Ausführungsbeispiel der Erfindung für eine nicht fortlaufende Gestaltungsform in Draufsicht auf die Ebene einer Trägerstruktur.

Further advantages and embodiments of the invention will become apparent from the drawing; in this show:

Fig. 1

a conventional configuration of a rotary screen,

Fig. 2

two embodiments of the invention with a topographical pattern in the form of a dot pattern or a topographic pattern in the form of a motif pattern,

Fig. 3

an embodiment of the invention with a topographical pattern on the surface of a woven papermachine fabric,

Fig. 4

an embodiment of the invention with a topographical pattern on the surface of a woven base fabric and in the structure of a wet felt,

Fig. 5

an embodiment of the invention with regard to the application of the topographical pattern by the semi-continuous method, ie section by section,

Fig. 6

an embodiment of the invention with respect to the application of the topographical pattern by the continuous process, ie in the form of a spiral,

Fig. 7

an embodiment of the invention for a continuous design form in plan view of the plane of a support structure and

Fig. 8

an embodiment of the invention for a non-continuous design form in plan view of the plane of a support structure.

Fig. 2 shows two embodiments of the invention with a topographical pattern in the form of a dot pattern 18 and a topographic pattern in the form of a motif pattern 20th

The topographic pattern 18, 20 may thus be e.g. take the form of a unique motif or a symmetrical grid of polymer dots. The polymer is supplied to the support structure through a rotary screen having the motif or dot pattern engraved therein. The volume of polymer which is supplied to the papermachine clothing is controlled by the dimensions of the screen motif and also by the polymer pumping system. The polymer penetration depth into the support structure of the fabric is influenced by the force generated by the pump which forces the polymer through the rotary fabric.

The topographical pattern may be used as an outer or inner feature of the papermachine fabric. As an external feature that will used topographical patterns to influence the paper formation on the paper side of the fabric. In contrast, the topographic pattern is applied, for example, as an intrinsic feature on the surface of the support structure of a press felt, the support structure being within the composite structure of the press felt and thus affecting the paper formation by wet pressing.

Fig. 3 shows an embodiment of the invention with a topographic pattern 22 on the paper side of a woven papermachine fabric, such as a forming fabric.

Fig. 4 shows an embodiment of the invention with a topographic pattern 24 on the surface of a woven and thus load-bearing support structure and in the structure of a wet felt.

Fig. 5 shows an embodiment of the invention with respect to the application of the topographical pattern by the semi-continuous method in which each juxtaposed pattern sections are formed, each of which forms an enclosed in the circumferential direction of the support structure endless loop. After formation of each section, the rotary screen 28 is translated by the width of that section before the next section is applied to the support structure 26.

In the Fig. 5 is an initial section labeled "30" and a second section labeled "32".

Fig. 6 shows an embodiment of the invention with respect to the application of the topographical pattern by the continuous process, ie in the form of a spiral.

In the continuous mode, the entire width of the papermachine fabric 26 is covered with the topographic pattern in one go. The continuous mode is achieved by slowly traversing the rotary screen 28 relative to the fabric, so that the pattern is applied in a helical fashion. The spiral angle movement of the wire is determined by a number of interconnected process parameters, which include the amount of clothing, the clothing width, the clothing speed, the screen circumference, the screen pattern pitch and the screen speed. The high degree of process control during continuous helical operation allows accurate pattern matching, which can only occur within a tolerance of 0.1 mm.

In this Fig. 6 is the paper machine clothing 26 and the rotary screen 28 can be seen, which performs a spiral angle movement.

Topographic pattern matching is an important and unique feature of the invention and is essential to meeting quality standards during the papermaking process. The topographical pattern matching concerns both continuous and discontinuous motif and point design forms.

Fig. 7 shows a plan view of the plane of a support structure for a continuous design form. In this case, a first pattern section and a second pattern section and the pattern matching point can be seen. The offset of the two pattern sections in the plane of the support structure is 0.1 mm or less.

Furthermore, the vertical offset of the two pattern sections, ie the offset perpendicular to the plane of the support structure, is 0.1 mm or less.

In the ongoing designs, the emphasis is placed on maintaining a net-like pattern.

Fig. 8 shows an embodiment of the invention for a non-continuous design.

It is in this Fig. 8 to recognize a first pattern portion and a second pattern portion and a screen pitch.

In the non-contiguous designs emphasis is placed on maintaining the screen pitch between motifs or dots.

Also in this example, the offset of the two pattern sections in the plane of the support structure is 0.1 mm or less.

LIST OF REFERENCE NUMBERS

10

End ring, end ring

12

scree

14

application width

16

machine width

18

Dot pattern, topographical pattern

20

Motif pattern, topographical pattern

22

topographical pattern

24

topographical pattern

26

Paper machine clothing

28

rotary screen

30

initial section

32

second part

Claims (15)

1. Method for producing a topographical pattern on or in a papermachine fabric (26), in which a topographical polymer pattern (18-24) is produced by means of a rotary screen (28), and in which the polymer is supplied to the papermachine fabric (26) via the rotary screen (28), characterized in that the rotary screen (28) extends only over part of the width of a carrier structure of the fabric and characterized in that, in order to form the topographical polymer pattern (18-24) on the carrier structure, the rotary screen (28) is moved relative to the carrier structure in such a way that, with respect to the width of the carrier structure, the topographical polymer structure is formed by a plurality of topographical pattern sections arranged beside one another which, at least in the plane of the carrier structure, have an offset of 0.1 mm or less.
2. Method according to Claim 1, characterized in that a rotary screen (28) having an engraved topographical pattern is used.
3. Method according to Claim 1 or 2, characterized in that the volume of the polymer supplied to the papermachine fabric (26) can be controlled by the dimensions of the rotary screen pattern and by the polymer pumping system.
4. Method according to one of the preceding claims, characterized in that the topographical polymer pattern (18-24) is produced in the form of a single motif.
5. Method according to one of Claims 1 to 4, characterized in that the topographical polymer pattern (18-24) is produced in the form of a symmetrical matrix of polymer dots.
6. Method according to one of the preceding claims, characterized in that the topographical polymer pattern (18-24) is produced continuously.
7. Method according to Claim 6, characterized in that the topographical polymer pattern (18-24) is produced in a spiral way.
8. Method according to Claim 6 or 7, characterized in that the topographical polymer pattern (18-24) is produced while maintaining a net-like pattern.
9. Method according to one of Claims 1 to 5, characterized in that the topographical polymer pattern (18-24) is produced section by section.
10. Method according to one of the preceding claims, characterized in that the polymer is supplied continuously to the rotary screen (28).
11. Method according to one of the preceding claims, characterized in that the polymer viscosity is chosen to be 70 Pa.s (70,000 cP).
12. Method according to Claim 11, characterized in that the polymer viscosity lies in a range from about 100 to about 150 Pa.s (about 100,000 to about 150,000 cP).
13. Method according to one of the preceding claims, characterized in that the pattern height above the papermachine fabric (26) lies in a range from 0.05 mm to 1.0 mm.
14. Method according to one of the preceding claims, characterized in that, in order to produce the topographical polymer pattern (18-24), use is made of a polymer which comprises at least one of the following constituents or any desired combination thereof: polyurethane, silicone, polyureas.
15. Method according to one of the preceding claims, characterized in that use is made of a rotary screen (28) having a width of up to 2 m.

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