EP1199403A2 - Headbox trailing element in a paper-, board-, or tissue machine - Google Patents

Abstract

A lamella (10.1, 10.2) positionable in a headbox of a web production machine, is formed by a high-performance polymer(s) (11). The polymer(s) has high stability, high heat resistance, and good to very good resistance to an alkaline solution or an acid. An Independent claim is included for a head box of a web production machine.

Description

The invention relates to a lamella of a headbox of a paper, cardboard or Tissue machine.

Such a lamella of a headbox in the form of a multilayer headbox is known from the applicant's European patent application EP 0 681 057 A2 (PA10068 EP). There is at least one lamella in the nozzle of the disclosed headbox, which keeps two adjacent suspension streams separated from one another up to the region of an outlet gap. The lamella is made of a plastic, the elastic modulus of which is preferably less than 80,000 N / mm ² .

According to the known prior art, this plastic is a polycarbonate (PC), which due to its special properties is an unstoppable Career as a material for many modern and technically demanding applications has made. For example, the high-tech polycarbonate became the Bayer AG under the Makralon® brand and that of General Electric World-famous under the Lexan® brand name.

The polycarbonate is used in low-cost fins for applications in which the use of expensive fins is not possible or sensible for economic reasons, such as single-layer headboxes in which the fins end inside the nozzle.
A disadvantage of using polycarbonate as the material for lamellas is that the connection between the lamella and the headbox (turbulence generator) has to be made larger than desired because of the low strength of polycarbonate. In addition, the polycarbonate has mechanical, chemical, thermal and processing disadvantages.

Carbon fiber composites are better, but also more expensive, materials for fins forth, by means of which slats are made from several parts. The carbon fiber composites are particularly suitable for applications with very high demands on form stability and constancy of the Beam thickness cross profile, especially in multi-layer headboxes.

All previously known and used materials for slats for use in Headboxes for the production of one from at least one fiber suspension formed fibrous web, in particular a paper or cardboard web, is common, that the slats are sensitive to mechanical forces, such as handling. Furthermore, they have low resistance against high temperatures and exposure to alkali Clean the headbox using "Boil Out". Also reduce the properties of the materials listed above the service life of the slats.

It is therefore an object of the invention to provide a headbox of the type mentioned to improve such that its lamella is both a better cost-benefit ratio for all possible applications as well as the various Withstands operating conditions longer.

This object is achieved according to the invention in a headbox of the type mentioned at the outset in that the lamella is formed from at least one high-performance polymer which has high strength, high heat resistance and good to very good alkali and / or acid resistance.
High-performance polymers are among the thermoplastics, called thermoplasts for short, and are characterized, among other things, by a very high maximum service temperature according to UL 746 B (US test regulations from Underwright Laboratories) and IEC 216, which is in the range of 160 ° C to 260 ° C , a very good heat resistance, a good to very good alkali resistance and increased strength values.
Because of these exemplary properties (mechanical, thermal and chemical), high-performance polymers are ideally suited for use as a material for lamellas. They have an increased cost-benefit ratio and can withstand difficult operating conditions for longer.

In order to increase the mechanical properties of the lamella and to reduce its sensitivity to the effects of mechanical forces, the high-performance polymer has a tensile strength R _m (DIN 53455) in the range from 50 N / mm ² to 150 N / mm ² , preferably from 70 N / mm ² to 110 N / mm ² , and an elongation A ₅ (DIN 53455) in the range from 20% to 80%, preferably from 30% to 60%. In addition, the high-performance polymer has a modulus of elasticity E (DIN 53457, ISO 527-2) in the range from 500 N / mm ² to 10,000 N / mm ² , preferably from 1,000 N / mm ² to 5,000 N / mm ² .

The connection between the lamella and the turbulence generator can be made smaller if the high-performance polymer has a notched impact strength (ISO 179) of 40 kJ / m ² to 100 kJ / m ² , preferably 45 kJ / m ² to 90 kJ / m ² ,

The behavior of the lamella against moisture and water (resistance to hydrolysis) is significantly improved when the high performance polymer absorbs moisture FA (ISO 62) in the range of 0.05% to 2%, preferably from 0.2% to 1.2%.

To enable efficient and cost-effective cleaning of the slat, the high-performance polymer has a heat resistance WB (DIN 53461) in Range from 120 ° C to 230 ° C, preferably from 170 ° C to 220 ° C, and a good to very good alkali resistance. With these values is the application cleaning by "boiling out" the headbox, that is, the existence of temperatures in the range of 100 ° C with simultaneous application of 20% sodium hydroxide solution (NaOH) possible.

In order to ensure the dimensional stability of the lamella even during operation, the high-performance polymer has a low swelling Q, in particular a low linear swelling Q _L , in the preferred range from 0.02% to 0.1%.

From the group of high-performance polymers that meet the above requirements in operation and during the cleaning of a headbox in an excellent manner polyphenyl sulfone (PPSU), the polyether sulfone, is recommended (PES), the polyetherimide (PEI) and the polysulfone (PSU), the first three High-performance polymers have only been developed in the recent past.

Depending on the application, it can go as far as the area of the nozzle end Lamella in its structureless end area - seen in the direction of flow blunt slat end with a height of less than 0.4 mm, preferably of less than 0.3 mm, or in its structured end area - in the direction of flow seen - have a blunt slat end with a height of greater than 0.5 mm. The structured end area can further structure the structure of Grooves with rectangular and / or wedge-shaped and / or parabolic and / or have a round shape with constant and / or different depth.

In an advantageous embodiment, the lamella is complete in a homogeneous structure formed from a high-performance polymer, in an alternative embodiment is only the slat end is formed from at least one high-performance polymer. These two configurations therefore ensure that at least the critical one Area of a slat, namely the slat end in the preferred embodiment a lamellar tip, the favorable properties of a high-performance polymer exhibit.

The lamella according to the invention can also be sectioned in a headbox Material density control (dilution water technology) should be designed. With this design of the headbox, the possibility is created that Throughput, the consistency and thus the basis weight and the fiber orientation to be able to regulate in sections, and this with the presence of optimal slats.

The current and future production requirements with regard to production quantity and to take account of the like, the slat in one Headbox for a jet speed greater than 1,500 m / s, preferably greater than 1,800 m / s.

The lamella can also be designed in a multi-layer headbox Headbox to be installed, the lamella, which is essentially the aforementioned Features as a separating lamella of the multi-layer headbox is trained.

It goes without saying that the aforementioned and still to be explained below Features of the invention not only in the respectively specified combination, but can also be used in other combinations or alone are without departing from the scope of the invention.

Further features and advantages of the invention emerge from the subclaims and the following description of preferred exemplary embodiments with reference to the drawing.

Figur 1:

einen schematischen Längsschnitt eines Stoffauflaufs mit zwei erfindungsgemäßen Lamellen;

Figur 2:

eine schematische Raumansicht eines Mehrschichten-Stoffauflaufs mit einer erfindungsgemäßen Lamelle;

Figur 3a:

einen schematischen Längsschnitt eines Endbereichs einer erfindungsgemäßen Lamelle; und

Figur 3b:

schematische Draufsichten auf strukturierte Endbereiche von erfindungsgemäßen Lamellen.

Show it

Figure 1:

a schematic longitudinal section of a headbox with two lamellae according to the invention;

Figure 2:

is a schematic spatial view of a multi-layer headbox with a lamella according to the invention;

Figure 3a:

a schematic longitudinal section of an end region of a lamella according to the invention; and

Figure 3b:

schematic plan views of structured end areas of lamellae according to the invention.

FIG. 1 shows a headbox 1 in a schematic longitudinal section Headbox 1 comprises a feed device 2 for the fiber suspension 3 in the headbox 1. The feed device 2 is designed as a transverse distribution pipe 4; However, in a further embodiment, it can also be a central distributor with supply hoses include. The headbox 1 still consists of a machine width Device for generating microturbulence ("turbulence generator") 5, one machine-wide prechamber 6 in the flow direction S (arrow) of the fiber suspension 3 is upstream. The turbulence generator 5 is according to the State of the art from a variety of rows and columns side by side and superimposed turbulence pipes 5.2 of various shapes. the Turbulence generator 5 is in the flow direction S (arrow) of the fiber suspension 3 a machine-wide outlet nozzle 7 for distributing the fiber suspension 3 between two sieves (lower sieve 8.1, upper sieve 8.2) of a not shown Twin wire former (gap former) 9 downstream; in another version, the Fibrous suspension 3, however, only on a wire of a Fourdrinier or hybrid former be distributed. There are two in the outlet nozzle 7 of the headbox 1 machine-wide slats 10.1, 10.2 attached.

According to the invention, the two lamellae 10.1, 10.2 are formed from at least one high-performance polymer 11 which has high strength, high heat resistance and good to very good alkali and / or acid resistance.
The high-performance polymer 11 has a tensile strength R _m (DIN 53455) in the range from 50 N / mm ² to 150 N / mm ² , preferably from 70 N / mm ² to 110 N / mm ² , and an elongation at break A ₅ (DIN 53455) in the range from 20% to 80%, preferably from 30% to 60%. In addition, the high-performance polymer 11 has a modulus of elasticity E (DIN 53457, ISO 527-2) in the range from 500 N / mm ² to 10,000 N / mm ² , preferably from 1,000 N / mm ² to 5,000 N / mm ² .
The high-performance polymer 11 also has a notched impact strength (ISO 179) of 40 kJ / m ² to 100 kJ / m ² , preferably 45 kJ / m ² to 90 kJ / m ² , so that the connection between the lamella 10.1, 10.2 and the turbulence generator 5 can be made smaller.
So that the behavior of the two lamellae 10.1, 10.2 against moisture and water (resistance to hydrolysis) is decisively improved, the high-performance polymer 11 has a moisture absorption FA (ISO 62) in the range from 0.05% to 2%, preferably from 0.2% to 1 , 2%, on.
From the point of view of cleaning technology, the high-performance polymer 11 of the two fins 10.1, 10.2 has a heat resistance WB (DIN 53461) in the range from 120 ° C. to 230 ° C., preferably from 170 ° C. to 220 ° C., and a good to very good alkali resistance. since with these values the use of cleaning by "boiling out" of the headbox 1, that is, the presence of temperatures in the range of 100 ° C. with simultaneous use of 20% sodium hydroxide solution (NaOH) is made possible.
In order that the dimensional stability of the fins 10.1, 10.2 is also ensured during operation, the high-performance polymer 11 has a low swelling Q, in particular a low linear swelling Q _L , in the preferred range from 0.02% to 0.1%.
From the group of high-performance polymers 11, which meet the requirements placed on them during operation and during the cleaning of a headbox in an excellent manner, the polyphenyl sulfone (PPSU), the polyether sulfone (PES), the polyether imide (PEI) and the polysulfone (PSU) are recommended ).
Advantageously, the two lamellae 10.1, 10.2 are each made of a high-performance polymer in a homogeneous structure, it being understood that different high-performance polymers can be used.
In FIG. 1 it can also be seen that the lamella 10.1, which has a blunt lamella end, is articulated and the lamella 10.2, which has a pointed lamella end, rigidly at its ends 12.1, 12.2 on the turbulence generator, which are directed counter to the flow direction S (arrow) of the fibrous suspension 3 5 are stored; However, in a further embodiment, they can also be stored in the turbulence generator 5, that is to say between two rows of the turbulence pipes 5.2.
In order to take into account the current and future production requirements with regard to production volume and the like, the lamellae 10.1, 10.2 of the headbox 1 are, from a hydraulic and fluidic point of view, for a jet speed v _S (arrow) of greater than 1,500 m / s, preferably greater than 1,800 m / s , designed.

The headbox shown in Figure 2 in a schematic spatial view is as Multilayer headbox 1.1 is formed, the feed devices shown only schematically 2, 2.1, 2.2 for feeding various fiber suspensions 3, 3.1, 3.2. The outlet nozzle 7 is in a known manner by two machine-wide current guiding walls 13.1, 13.2 limited. These are about ever a known turbulence generator 5, 5.1 with a central stationary partition 14 connected. At the outlet end of the partition 14 is again by means of a joint 15 a separating lamella 16 is pivotally attached. deviant Of these, the partition plate 16 can also be rigidly attached to the partition 14.

According to the invention, the multilayer headbox 1.1 is designed as a headbox with sectioned stock density control (dilution water technology) as claimed in the applicant's German patent application DE 40 19 593 A1 (PA04598 DE). The content of this published specification is hereby incorporated in full in the disclosure content of this application, without further reference being made to it. A first fibrous suspension stream with a high consistency Q _H.1 reaches the turbulence generator 5 via a transverse distribution pipe 4 and via a row of sectional feed lines 17 ... 17.n branched off from it. In deviation from FIG. 2, each sectional feed line 17 ... 17. A volume flow controller can be provided. In order to be able to implement a sectioned consistency control, a second pulp suspension stream with a low consistency Q _L , for example white water-I, is led into the sectioned supply lines 17 ... 17.n via a cross distribution pipe 4.1 and sectional supply lines 18 ... 18.n , Each of the sectional feed lines 18 ... 18.n has a control valve 19 ... 19.n in order to guide a controllable sectional fiber suspension flow Q _L to an associated mixing point 20 ... 20.n, where it is connected to the sectional fiber suspension stream Q _{H.1 is} mixed. A third fibrous suspension stream with a medium or high consistency Q _H.2 reaches the turbulence generator 5.1 via a transverse distribution pipe 4.2 and via a row of sectional feed lines 21 ... 21.n branched off from it. In this configuration of the multi-layer headbox 1.1, this creates the possibility of being able to regulate the throughput, the material density and thus the basis weight and the fiber orientation sectionally, and this in the presence of an optimal separating lamella 16.
Of course, the headbox 1 shown in FIG. 1 can also be designed as a headbox with sectioned stock density control (dilution water technology), in accordance with the aforementioned statements.
Furthermore, the separating lamella 16 of the multi-layer headbox 1.1 is formed from a high-performance polymer 11 which essentially has the aforementioned properties.
Another advantage of using a high-performance polymer as the lamella material is that even in the event of an unwanted failure of the headbox pump, which results in very high pressures between the layers in the nozzle, there is no lamella breakage due to the good mechanical properties of high-performance polymers is coming.

FIG. 3a shows a schematic longitudinal section of an end region 22 of a lamella 10.1 according to the invention.
According to the invention, the lamella 10.1 extending into the area of the nozzle end can have a blunt lamella end 23 with a height H of less than 0.4 mm, preferably less than 0.3 mm, in its structureless end area 22 - seen in the flow direction S (arrow) , In the end region 22, the lamella 10.1 can have a constant height h or a decreasing height h '.
Furthermore, according to the invention, the lamella 10.1 extending into the region of the nozzle end can have a blunt lamella end 23 with a height H of greater than 0.5 mm in its structured end region 22, as seen in the flow direction S (arrow). In a further embodiment, the structured end region 22 can have the structure of grooves 24 with a rectangular and / or wedge-shaped and / or parabolic and / or round shape with constant and / or different depth T.

Furthermore, at least the slat end 23 can be made of at least one high-performance polymer 11 be formed (dashed dividing line).

FIG. 3 b shows three schematic and exemplary top views according to the view arrow B of FIG. 3 a on structured end regions 22 of slats 10.1 according to the invention.
It is clearly evident that the structured end regions 22 of the slats 10.1 according to the invention have a plurality of grooves 24 with rectangular ( A ) and / or wedge-shaped ( B ) and / or parabolic ( C ) and / or round shape with constant and / or different depths can have.
Further combinations with regard to the design of the structured end regions are known from the applicant's German published application DE 43 29 810 A1 (PA05205 DE). The content of this published specification is hereby incorporated in full in the disclosure content of this application, without further reference being made to it.

In summary, it should be noted that a headbox of the invention initially mentioned type is created, the lamella of which is both a better one Has cost-benefit ratio for all possible use cases as well withstands the various operating conditions for longer.

LIST OF REFERENCE NUMBERS

1

headbox

1.1

Multi-layer headbox

2, 2.1, 2.2

feeder

3, 3.1, 3.2

Fibrous suspension

4, 4.1, 4.2

transverse distribution

5, 5.1

turbulence generator

5.2

turbulence tube

6

antechamber

7

slice

8.1

bottom wire

8.2

top wire

9

Twin wire former (gap former)

10.1, 10.2

lamella

11

High-performance polymer

12.1, 12.2

The End

13.1, 13.2

Machine-wide power supply wall

14

partition wall

15

joint

16

separating lamella

17 ... 17.n

Sectional feed line

18 ... 18.n

Sectional feed line

19 ... 19.n

control valve

20 ... 20.n

mixing point

21 ... 21.n

Sectional feed line

22

end

23

lamella end

24

groove

A , B , C

Top view

B

view arrow

H

height

H

Height (constant)

H'

Height (decreasing)

Q _H.1

First pulp suspension stream with high cons.

Q _H.2

Third fiber suspension stream with medium / high. Cons.

Q _L

Second pulp suspension stream with low cons.

S

flow direction

T

depth

v _p

jet speed

Claims (16)

Lamella (10.1, 10.2) of a headbox (1) of a paper, cardboard or tissue machine,
characterized in that the lamella (10.1, 10.2) is formed from at least one high-performance polymer (11) which has high strength, high heat resistance and good to very good alkali and / or acid resistance. Lamella (10.1, 10.2) according to claim 1,
characterized in that the high-performance polymer (11) has a tensile strength R _m (DIN 53455) in the range from 50 N / mm ² to 150 N / mm ² , preferably from 70 N / mm ² to 110 N / mm ² , and an elongation at break A ₅ (DIN 53455) in the range from 20% to 80%, preferably from 30% to 60%. Lamella (10.1, 10.2) according to claim 1 or 2,
characterized in that the high-performance polymer (11) has an elastic modulus E (DIN 53457, ISO 527-2) in the range from 500 N / mm ² to 10,000 N / mm ² , preferably from 1,000 N / mm ² to 5,000 N / mm ² , having. Lamella (10.1, 10.2) according to one of the preceding claims,
characterized in that the high-performance polymer (11) has a notched impact strength (ISO 179) of 40 kJ / m ² to 100 kJ / m ² , preferably 45 kJ / m ² to 90 kJ / m ² . Lamella (10.1, 10.2) according to one of the preceding claims,
characterized in that the high-performance polymer (11) has a moisture absorption FA (ISO 62) in the range from 0.05% to 2%, preferably from 0.2% to 1.2%. Lamella (10.1, 10.2) according to one of the preceding claims,
characterized in that the high-performance polymer (11) has a heat resistance WB (DIN 53461) in the range from 120 ° C to 230 ° C, preferably from 170 ° C to 220 ° C. Lamella (10.1, 10.2) according to one of the preceding claims,
characterized in that the high-performance polymer (11) has a low swelling Q, in particular a low linear swelling Q _L , in the preferred range from 0.02% to 0.1%. Lamella (10.1, 10.2) according to one of the preceding claims,
characterized in that the high-performance polymer (11) is a polyphenyl sulfone (PPSU), a polyether sulfone (PES), a polyetherimide (PEI) or a polysulfone (PSU). Lamella (10.1, 10.2) according to one of the preceding claims,
characterized in that the lamella (10.1, 10.2) extending into the region of the nozzle end has a blunt lamella end (23) with a height (H) of less than 0.4 in its structureless end region (22) as seen in the direction of flow (S) mm, preferably less than 0.3 mm. Lamella (10.1, 10.2) according to one of claims 1 to 8,
characterized in that the lamella (10.1, 10.2) extending into the area of the nozzle end has a blunt lamella end (23) with a height (H) of greater than 0.5 in its structured end area (22) as seen in the direction of flow (S) mm. Lamella (10.1, 10.2) according to claim 10,
characterized in that the structured end region (22) has the structure of grooves (24) with rectangular and / or wedge-shaped and / or parabolic and / or round shape with constant and / or different depths (T). Lamella (10.1, 10.2) according to one of the preceding claims,
characterized in that at least the slat end (23) is formed from at least one high-performance polymer (11). Lamella (10.1, 10.2) according to one of claims 1 to 11,
characterized in that the lamella (10.1, 10.2) is formed in a homogeneous structure from a high-performance polymer (11). Lamella (10.1, 10.2) according to one of the preceding claims,
characterized in that the lamella (10.1, 10.2) is installed in a headbox (1) with sectioned material density control (dilution water technology). Lamella (10.1, 10.2) according to one of the preceding claims,
characterized in that the lamella (10.1, 10.2) is installed in a headbox (1) for a jet speed (v _s ) of greater than 1,500 m / s, preferably greater than 1,800 m / s. Lamella (10.1, 10.2) according to one of the preceding claims,
characterized, that the lamella (10.1, 10.2) is installed in a headbox (1) designed as a multi-layer headbox (1.1) and that the lamella (10.1, 10.2) is designed as a separating lamella (16).

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