EP0863254B1 - Process and paper machine to manufacture a multilayer fibrous web - Google Patents

Description

The invention relates to a method for producing a multilayer fibrous web, in the machine direction seen from a first headbox a first layer is formed on a first former and at least from a second headbox on a second former a second layer is formed that is solid with the first Layer is connected.

The invention further relates to a papie machine for manufacturing a multilayer fibrous web, with a first headbox seen in the machine direction to form a first layer of the fibrous web on one first former, and with a second headbox for formation at least a second layer on a second former, the is firmly attached to the first layer.

From DE 44 02 274 A1 it is known a multi-layer fibrous web in the wire section by means of to form two twin wire formers, with a first layer of Fibrous web from a first headbox between one Bottom sieve and an upper sieve is formed. The top sieve of this Twin wire former also forms the bottom wire of one downstream twin wire former, on which another layer on the previously created layer is applied.

Such an arrangement is particularly for the production of suitable for multi-layer cardboard. However, there is always one certain minimum strength is required.

In addition, it is basically from DE 31 07 926 A1 known a twin wire former for multi-ply paper or Cardboard webs with several headbox exit openings use the different layers between a top sieve and a bottom sieve are produced one after the other and one above the other, by first a first layer from a fabric outlet opening is generated on the then from another fabric outlet a separately guided by means of a separating element Fibrous suspension applied to produce a second layer is, as well as, if necessary, a further location in a corresponding manner.

Such an arrangement is only for production of thicker, multi-layer packaging or cardboard papers suitable. Nor is there a clean separation of the layers from one another possible because the layers are still liquid are generated one above the other.

For the production of thin tissue papers, so-called Crescent former has proven itself, for example from DE 33 27 056 A1 or known from DE 17 61 505 A1 or DE-PS 17 61 505.

The layer formation takes place according to the crescent former principle by dewatering around a forming roller between a felt on the side facing the forming roller and a sieve the side facing away from the forming roller.

Such a former is formed by the use of a felt band especially for the production of thin, less tearproof papers, such as tissue papers.

However, multi-ply tissue papers, such as multi-ply, should Toilet paper or paper tissues, are produced so this is done according to the state of the art by using finished webs to be laid on top of each other to form multilayered sheets.

WO-A-95/13424 discloses a machine for the production of multilayer tissue papers with a twin wire former and a crescent form.

EP-A-0636745 discloses a machine for Production of a multi-layer paper web, on each former the layer formation between a guided over a forming roller gieb and a felt ribbon.

The object of the invention is therefore a paper machine and a method of making a multilayer Develop fibrous web, with at least two firm interconnected layers are generated separately, wherein also the production of thin, less tearproof individual layers should be made possible.

This object is achieved by the features of the method according to claim.

The process according to the invention enables a multi-layered process Manufacture fiber composite, the production of Fibrous webs with very thin, less tear-resistant individual layers possible that are firmly connected. There is also a sharp layer separation between the guaranteed individual layers.

In the method according to the invention takes place the merging of the individual layers is not already in the layer formation process but only after the completed one Layering through pressure.

This measure has the advantage of being complete separate layer formation a sharp layer separation what is possible even with very thin individual layers due to a separate white water channel with separate ones Headboxes are still supported.

With regard to the paper machine, the task solved by the features of the machine according to claim 5.

As previously mentioned, this is how manufacturing becomes of multi-layer fiber composites even with a very thin one Single layer enables.

At the same time, a sharp layer separation is guaranteed, with a separate white water channel Mixing fibers of the layers of the first web with fibers the second lane is largely avoided.

It goes without saying that of course in a corresponding manner three- or multi-layer fibrous webs can be produced.

The paper machine according to the invention can be used advantageous to produce paper webs in which on a first thicker layer that is created in the twin wire former, one second thinner layer is applied in the crescent former is produced.

In an additional development of the invention Forming roller of the second former provided resilient strips to the Forming roller can be pressed.

This can result in layer formation in the case of very thin layers get supported.

Additional features of the method according to the invention and the paper machine according to the invention are in contain the subclaims.

Fig. 1 und 1a

eine stark vereinfachte schematische Darstellung einer ersten Papiermaschine, die zur Herstellung von Karton geeignet ist, wobei zwei Crescent-Former hintereinander geschaltet sind;

Fig. 2

eine zweite Ausführung einer Papiermaschine mit zwei hintereinander geschalteten Crescent-Formern zur Herstellung von Tissue-Papieren;

Fig. 3

eine weitere Ausführung einer Papiermaschine, die zur Herstellung von Karton-Papieren geeignet ist, wobei zwei Schichten zunächst voneinander getrennt hergestellt und dann zusammengegautscht werden;

Fig. 4

eine Abwandlung der Ausführung gemäß Fig. 3, die zur Herstellung von Tissue-Papieren geeignet ist und

Fig. 5

eine Darstellung einer erfindungsgemäßen Papiermaschine.

Further features and advantages of the invention result from the following description of a preferred exemplary embodiment with reference to the drawing. Show it:

1 and 1a

a highly simplified schematic representation of a first paper machine which is suitable for the production of cardboard, with two crescent formers being connected in series;

Fig. 2

a second embodiment of a paper machine with two crescent formers connected in series for the production of tissue papers;

Fig. 3

a further embodiment of a paper machine, which is suitable for the production of cardboard papers, wherein two layers are first produced separately from one another and then squeezed together;

Fig. 4

a modification of the embodiment of FIG. 3, which is suitable for the production of tissue papers and

Fig. 5

an illustration of a paper machine according to the invention.

In those shown in Figures 1, 1a, and 2 to 4 Paper machines are not exemplary embodiments the invention.

A first version of a paper machine is shown in FIGS. 1 and 1a and overall with the number Designated 10.

It is a paper machine, preferably is used for the production of cardboard.

The paper machine 10 comprises a first, with the total Number 12 designated headbox, on which by means of a Crescent former trained first former 14 a first Layer of a fibrous web is generated. This is about a forming roller 16 guided a felt belt 22 over which a sieve 20 runs. The first headbox 12 becomes a fibrous suspension in the between the felt belt 22 and the sieve 20th formed enema zwickel 17 shot in and passes through the arrows shown in a tub 18 in which the Liquid is collected. The first so between the felt tape 22 and the screen 20 layer formed on the forming roller 16 reaches a second former 24 on the felt belt 22, the is also designed as a crescent former. Again will a fiber suspension from a second headbox 23 in an inlet gusset between the felt belt 22 and a sieve 30 shot, so the second layer on a second Forming roller 26 to form. Again, the exiting Liquid as shown by the arrows in a tub 28 caught.

The felt tape 22 on which the two are superimposed Layers are now formed over a plurality of Deflection rollers led to a wet press coming from an upper one Press roll 32 and a lower press roll 34 is formed and can be designed as an extended nip press. After passing through through the press 32, 34, the felt belt 22 is over pulleys diverted upwards and finally back to the first former 14 returned. The fibrous web 48 is then through another double felted press with a lower suction press roll 38 and an upper counter roller 40.

The fibrous web 48 is then pulled by means of a suction roll 42 removed and transferred to a dryer 44 to be in a subordinate dryer section to be dried, of which only a first drying cylinder 46 is shown.

The numbers 35 in FIGS. 1 and 1a indicate the transfer characterized, since Fig. 1a is the continuation of Fig. 1.

A modification of the paper machine according to FIG. 1 is shown in FIG. 2 shown and designated overall by the number 50. It is a paper machine for the production of tissue papers.

The same reference numbers are used for corresponding parts used.

The only difference from the previously described version is that the fibrous web after the formation of the first and the second layer on formers 14 and 24 on the felt belt 22 is not led through a press section, but directly by means of a roller 52 to a drying cylinder 54 or Yankee-Dryer with drying hood 56 is passed, of which the Fibrous web 48 is removed on a scraper 58.

Another version of a paper machine for the production of cardboard boxes is shown in Fig. 3 and designated overall by the number 60.

Here too, the same reference numbers are used for corresponding parts used.

The difference to the embodiment described with reference to FIG. 1 is that the two layers are not immediate sequentially formed on two formers, but independently are formed from each other, and that then the two Layers joined or squeezed together in a wet press become.

A first felt belt 22 runs over a forming roller 16a first crescent former 14a around which a first headbox 12a a pulp suspension in a between the Felt belt 22 and a sieve passed over the forming roller 16a 20a formed inlet gusset 17a is shot. The Excess liquid that emerges laterally is in a Catch pan 18a collected.

With a second crescent former 24a, a second Felt belt 22a in a corresponding manner a second layer of Fibrous web formed, again from a headbox 23a fiber suspension shot into an inlet gusset 27a between the via a forming roller 26a guided felt belt 22a and a circumferential sieve 30a formed is. The emerging liquid is in a tub 28a collected.

Both felt belts 22, 22a, on each of which a fibrous layer was additionally formed by suction boxes 62, 66 dewatered before they pass over a guide roller 61 of which they are brought together. Then the fibrous web 48 again from an upper suction box 64 and a lower suction box 68 pressurized before entering a downstream wet press 32, 34 arrives in the two previously separately formed layers under the effect of the applied Pressure connected and drained.

The rest of the course of the paper machine corresponds to that previously used 1 and 1a structure described.

Another variation of a paper machine is shown in FIG. 4 and overall with the number 70 designated.

Here too, the same reference numbers are used for corresponding parts as used in Fig. 3.

In contrast to that previously described with reference to FIG. 3 Execution, especially for the production of cardboard is suitable, it is the embodiment according to FIG. 4 around a paper machine for making tissue papers. Both previously on the separate felt belts 22 and 22a on the Crescent formers 14a, 24a are formed at the layers Guide of both belts 22, 22a joined together via a guide roller 61 and on a downstream wet press 52, 53 with each other couched. From one of the two press rolls 52 the Fibrous web 48 on the Yankee dryer 54 with drying hood 56 from which it is removed on a scraper 58.

5 shows an embodiment of a paper machine according to the invention shown, which is designated overall by the number 80.

This paper machine differs from those previously described Paper machines essentially in that one of the two formers is designed as a twin wire former, with the total number 86 is designated.

A second former is connected to the twin wire former 86 97, which is supplied from a headbox 99 and at which in the manner described above between one over one Forming roller passed a second belt to felt belt 102 and a sieve 101 Paper layer is generated with the in the twin wire former 86 generated first layer merged and in a first Wet press 81, 83 is then squeezed together.

The twin wire former 86 is supplied from a headbox 88 and comprises, in a manner known per se, a top sieve 98 and a Bottom sieve 100, which is guided over a breast roller 90. The Material jet emerges from the headbox 88 into the gap Breast roll 90 and top sieve 98.

A D-part 92 with pulsating elements adjoins the breast roller 90 Forming strips and further strips or support foils 94, 96 on.

Then the felt band 102 of the crescent former 97 is from below hinged to the top wire 98 of the twin wire former 86 so that the two layers produced are brought into contact with one another.

Through the first wet press 81, 83, preferably as a shoe press is formed, the felt band 102 runs in and out Upper felt 104.

Another press follows the first wet press 81, 83 which is preferably also designed as a shoe press 82, 84 and just as a felted press with one Upper felt 106 is executed.

After the second shoe press 82, 84, the paper web 48 finally by means of a dryer wire 108 through a dryer section performed in which they are between the individual drying cylinders 110 is dried in a manner known per se.

Through such a design with a combination of a first former, which is designed as a twin wire former and a second Formers, who are trained as crescent formers, can be advantageous to produce paper webs in which on a first thicker layer that is created in the twin wire former, one second thinner layer is applied in the crescent former is produced.

Claims (9)

1. Process for producing a multilayer fibrous web, in which, as viewed in the machine running direction, a first layer is formed from a first headbox (88) on a first former (86) and at least one second layer is formed from a second headbox (99) on a second former (97) and is firmly connected to the first layer, the layer formation on the first former (86) being carried out between wires (98, 100) led over a breast roll (90), the layer formation on the second former (97) being carried out between a felt (102) led over a forming roll and a wire (101), the two layers subsequently being brought into contact with each other and, by means of the felt (102), being led through at least one wet press (81, 83) to be couched.
2. Process according to Claim 1, characterized in that the felt (102) of the second former (97) is led up from below to the wire (98) of the first former (86).
3. Process according to one of the preceding claims, characterized in that, after the wet press (81, 83), the two layers are fed to a further, preferably single-felted, press (82, 84).
4. Process according to one of the preceding claims, characterized in that, after the at least one wet press (81, 83, 82, 84), the two layers are led through a drying section by means of a dryer fabric (108).
5. Papermaking machine (80) for producing a multilayer fibrous web, having, as viewed in the machine running direction, a first headbox (86) for forming a first layer of the fibrous web on a first former (86), and having a second headbox (99) for forming at least one second layer on a second former (97), which layer is firmly connected to the first layer, the first former (86) being constructed as a twin-wire former having two wires (98,100) led over a breast roll (90), the second former (97) being constructed as a Crescent former with a felt (102) led over a forming roll and a wire (101), and the two layers subsequently being brought into contact with each other and, by means of the felt (102), led through at least one wet press (81, 83) for couching.
6. Papermaking machine (80) according to Claim 5, characterized in that the first wet press (81, 83) is followed by a further, preferably single-felted, press (82, 84).
7. Papermaking machine (80) according to Claim 5 or 6, characterized in that at least one of the presses (81, 83, 82, 84) is constructed as a shoe press.
8. Papermaking machine (80) according to one of Claims 5 to 7, characterized in that the breast roll (90) of the first former (86) is followed by a D section (92) having pulsating forming foils and further foils or supporting foils (94, 96).
9. Papermaking machine (80) according to one of Claims 5 to 8, characterized in that compliant foils are provided on the forming roll of the second former (97) and can be pressed against the forming roll.

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