DE102022122488A1 - Device for producing a fiber mat web and corresponding method - Google Patents

Abstract

A device for producing a fiber mat web, in particular a structured and dry-formed tissue paper web or nonwoven web, from a fibrous starting material, comprises a provision device for providing the fibrous starting material, a processing device for low-water processing of the provided starting material, a forming device for forming a flat fiber mat web from the prepared starting material by a dry forming process and a structuring device for structuring the flat fiber mat web, the structuring device comprising at least a first structuring unit and a second structuring unit, the first structuring unit for introducing a first pattern into the fiber mat web and the second structuring unit for introducing a second pattern into the fiber mat web are formed and the second structuring unit is arranged behind the first structuring unit in the web running direction, so that a third pattern can be generated in the fiber mat web by superimposing the first and second patterns. The present invention also relates to a corresponding method.

Description

The invention relates to a device and a method for producing a fiber mat web.

In a known method for the low-water production of a fiber mat web, fibrous-containing starting material is processed with low water content and the resulting fiber material, which comprises individual fibers and/or fiber bundles, is formed into a flat fiber mat web using a dry forming process. In the course of efforts to optimize the manufacturing processes for fibrous webs with regard to reducing energy consumption and CO2 emissions, more and more dry forming processes and dry laying processes are being used. With these processes, the strength of the fibrous webs can no longer be adequately achieved through the formation of hydrogen bonds, since little or no water is used and the fibers are therefore almost dry-formed or dry-laid to form the web.

The formed fiber mat web is then solidified by spraying water and then applying pressure and temperature. Such a method is, for example, from the publication WO 2019/1 376 67 A1 known.

The fiber mat web obtained can be, for example, a tissue paper web or nonwoven web, whereby a tissue paper web or nonwoven web is to be understood, for example, as an absorbent hygiene paper, which is used, among other things, as toilet paper, kitchen paper, paper napkin or paper handkerchief. However, the term “fiber mat sheet” is not limited to this and can also describe, for example, a tablecloth made of cellulose or cardboard or the like.

In general, it is desirable to provide the fiber mat web with a pattern, since a visually and tactilely more appealing surface of the fiber mat web can have a positive influence on the purchaser's purchasing decision. Conventionally, a roller or a screen, the surface of which is structured with a corresponding pattern, is pressed onto the formed fiber mat web. This can be done during the step of solidifying the formed fiber mat web.

However, the procedure described is only suitable for producing simple or less complex structures in the fiber mat web, since producing fine and/or detailed patterns requires expensive and complex manufacturing processes or devices. For example, the surface of a roller or a sieve that is pressed into the formed fiber mat web must be structured in a complex and cost-intensive manner, so that the roller or the sieve then also produces the desired complex pattern in the fiber mat web.

It is therefore an object of the present invention to provide a method and an apparatus for economical production of an improved fiber mat web.

This object is achieved according to the invention by a device with the features of claim 1 and in particular in that the device for producing a fiber mat web, in particular a structured and dry-formed tissue paper web or nonwoven web, from a fibrous starting material, a provision device for providing the fibrous starting material, a processing device for low-water processing of the provided starting material, a forming device for forming a flat fiber mat web from the processed starting material by a dry forming process, and a structuring device for structuring the flat fiber mat web. The structuring device comprises at least a first structuring unit and a second structuring unit, wherein the first structuring unit is designed to introduce a first pattern into the fiber mat web and the second structuring unit is designed to introduce a second pattern into the fiber mat web and the second structuring unit is arranged behind the first structuring unit in the web running direction , so that a third pattern can be created in the fiber mat web by superimposing the first and second patterns.

By superimposing the first and second patterns (basic patterns), which can be designed to be comparatively simple, by the first and second structuring units, a more complex, visually and haptically appealing third pattern (target pattern) can be created in the fiber mat web in a simple and cost-effective manner. be generated.

Furthermore, the first and/or the second structuring unit can comprise at least one roller which has a comparatively simply structured surface for introducing the respective pattern. Since such rollers are comparatively easy to manufacture, this enables an additional reduction in costs.

The structured surface may have a hole pattern, a dot pattern, a groove pattern and/or a line pattern. In particular, this can respective patterns can be periodic, so that by taking advantage of the so-called moiré effect, the third pattern can be a pattern that appears very complex and has structures that are not present in any of the respective basic patterns and vary when the overlay is changed.

To efficiently introduce the respective patterns, the first and/or the second structuring unit can comprise at least one pair of rollers with a first and a second roller, which form a press nip. In particular, both structuring units can include a pair of rollers that form a first and a second press nip.

In addition, the first and second structuring units may comprise a pair of rollers with a first and a second roller, wherein the second roller of the first structuring unit forms the second roller of the second structuring unit.

Taking into account the fact that the formed fiber mat web can be thinner in the web running direction behind the first structuring unit than in front of it, the first press nip and the second press nip can be designed differently. In particular, different pressing forces can be provided in the first and second press nips and/or the nip widths of the first and second press nips can be different.

Furthermore, in order to compress the fiber mat web and thus, among other things, improve its tear resistance, the structuring device can be designed to not only solidify the fiber mat web locally to introduce the patterns, but also to solidify it over the area.

The object described above is also achieved according to the invention by a method with the features of claim 8 and in particular in that the method for producing a fiber mat web, in particular a structured tissue paper web or nonwoven web, from a fibrous starting material, in particular with a device according to the invention according to one of the embodiments described above, providing the fibrous starting material, low-water processing of the provided starting material, forming a flat fiber mat from the prepared starting material by a dry forming process, and structuring the flat fiber mat web by introducing a first pattern and a second pattern, so that a third pattern can be created.

To create an attractive third pattern, the first pattern and the second pattern can be introduced offset.

The first pattern and the second pattern can also be introduced superimposed.

Furthermore, the first pattern and the second pattern can be introduced in such a way that they overlap at least in sections.

Furthermore, the first pattern and the second pattern can be similar. However, the first pattern and the second pattern can also differ.

In particular, the first pattern and the second pattern each differ from the third pattern.

During the structuring step, the fiber mat web can not only be solidified locally to introduce the patterns, but also solidified or compacted over the area, for example in order to achieve improved tear resistance.

Furthermore, a fiber mat web is claimed, which is obtained by carrying out the method according to the invention.

The device according to the invention and the method according to the invention enable economical production of an improved fiber mat web, in particular a structured and dry-laid tissue paper web or nonwoven web with a basis weight of 10g/m ² to 50g/m ² , preferably from 12g/m ² to 45g/m ² .

• 1 eine schematische Querschnittansicht einer Ausführungsform einer erfindungsgemäßen Vorrichtung;
• 2 eine schematische Querschnittansicht einer weiteren Ausführungsform einer erfindungsgemäßen Vorrichtung; und
• 3A-C schematische Darstellungen der Überlagerung beispielhafter Muster.

The invention is described below by way of example using advantageous embodiments with reference to the accompanying drawings. Show it:

• 1 a schematic cross-sectional view of an embodiment of a device according to the invention;
• 2 a schematic cross-sectional view of a further embodiment of a device according to the invention; and
• 3A -C schematic representations of the overlay of exemplary patterns.

1 shows a schematic representation of an exemplary variant of a device 10 for producing a fiber mat web 12 according to the present invention. The device 10 comprises a provision device (not shown) for providing a fibrous starting material, a processing device (not shown) for low-water processing of the provided starting material and a forming device (also not shown) for forming a flat fiber mat web 12 from the prepared starting material by a dry forming process. Regarding the provision facility, the processing device and the forming device are exemplified in the publication WO 2019/1 376 67 A1 referred.

In low-water processing, the fibrous starting material has, for example, a dry content of more than 50%, in particular more than 70% and preferably more than 80%. In particular, the starting material can be air-dry.

The device 10 further comprises a support or carrying device 30 for receiving and carrying the fiber mat web 12 produced by the devices described above. The carrying device 30 can be designed as a sieve or belt or the like and serves to support and transport the fiber mat web 10 in the web running direction 20.

The device 10 also includes a structuring device 14 for structuring the flat fiber mat web 12, the structuring device 14 comprising a first structuring unit 14a and a second structuring unit 14b.

The first structuring unit 14a comprises a pair of rollers with a first roller 24a and a second roller 24b, the two rollers being arranged one above the other in the vertical direction (z direction in the drawings) and at a certain distance from one another. That is, an axis of rotation 34a of the first roller 24a of the first structuring unit 14a is arranged in the vertical direction above an axis of rotation 34b of the second roller 24b of the first structuring unit 14a. The vertical direction is a direction that is perpendicular to the web running direction 20 (x direction in the drawings) of the fiber mat web 12 and perpendicular to a width (y direction in the drawings) of the fiber mat web 12. The rollers 24a, 24b form a press nip 26a.

The second structuring unit 14b includes a pair of rollers with a first roller 24c and a second roller 24d, which form a second press nip 26b.

The nips 26a, 26b are selected or adjusted so that the respective pattern 16, 18 is introduced efficiently. Optionally, it is also possible to simultaneously deliberately press the fiber mat web 12 in one of the nips 26a, 26b or both in order to solidify it overall. It can happen or be desired that a thickness of the fiber mat web 12 is reduced in the first structuring unit 14a. In order to take this circumstance into account, the nip 26b downstream of the nip 26a can have correspondingly modified properties. However, different nip properties can also be due to other reasons, for example because the introduction of different patterns makes this necessary.

The first structuring unit 14a is designed to introduce a first pattern 16 into the fiber mat web 12 and the second structuring unit 14b is designed to introduce a second pattern 18 into the fiber mat web 12. In particular, the first roller 24a of the first structuring unit 14a has a structured surface for introducing the first pattern 16 into the fiber mat web 12 and the first roller 24c of the second structuring unit 14b has a structured surface for the subsequent, i.e. spatially and temporally offset, introduction of the second pattern 18 into the fiber mat web 12. The pairs of rollers 24a, 24b and 24c, 24d, which are arranged offset from one another in the web running direction 20 at a certain distance 32, thus enable the generation of a third pattern 22 by superimposing the first pattern 16 and the second pattern 18 in the fiber mat web 12.

Additionally or alternatively, it is possible to provide the rollers 24b and/or 24d with a pattern-generating surface.

Pattern-generating surfaces that can be manufactured cost-effectively have, for example, hole structures or line structures.

The patterns 16, 18 can be designed in various ways. For example, the structured surface of a roller 24 of the structuring units 14a, 14b can have a hole pattern, a dot pattern, a groove pattern and/or a line pattern (or any combination thereof) (cf. 3A , 3B , each on the left side). The structured surface can also have a checkered pattern or a diamond pattern or the like (cf. 3C , left side). Furthermore, structured surfaces of rollers are possible that have not just a single pattern, but a variety of different patterns.

As in 3A and 3B is shown, the first pattern 16 and the second pattern 18 can also be the same. The patterns 16, 18 can also differ, whereby an even more detailed and complex appearing third pattern 22 can be generated (see 3C , Left).

For an even more visually appealing design of the fiber mat web 12, the respective pattern 16, 18 can also be periodic, ie substructures 38 of the patterns such as the holes, dots, grooves, lines, rectangles, diamonds and the like are at the same distances - a period 36 - arranged to each other. This allows What can be achieved is that the third pattern 22 has structures that can be found neither in the first pattern 16 nor in the second pattern 18 (so-called Moire effect).

In addition, the second pattern can be introduced arbitrarily in relation to the first pattern. The first pattern 16 and the second pattern 18 can, for example, be introduced superimposed. But they can also be introduced in such a way that they differ at least in sections. In particular, a third pattern or target pattern 22 is generated, which differs from both the first pattern 16 and the second pattern 18.

For example, the first pattern 16 and the second pattern 18 can be introduced into the fiber mat web 12 in such a way that the respective substructures 38 of the patterns 16, 18 superimpose or overlap at least in sections (cf. 3A , right side). As mentioned, the patterns 16, 18 can basically be the same, but they are introduced into the fiber mat web 12 in the web running direction 20 and perpendicularly thereto.

In a first section 40 of the fiber mat web 12, in which the substructures 38 of the patterns are superimposed (cf. 3A , enlarged detail), the fiber mat web 12 is more solidified than in a second section 42 of the fiber mat web 12, in which only the first or second pattern 16 or 18 is introduced, and than in a third section 44 of the fiber mat web 12, in which no Pattern is introduced. Areas with different properties are created in the fiber mat web 12, which must be taken into account when designing the pattern. Or vice versa: By choosing suitable patterns 16, 18 and consciously combining them, the properties of the fiber mat web 12 can be consciously adjusted.

For example, by changing the relative position of introducing the second pattern 18 with respect to the first pattern 16, the area of the first section 40 can be varied with respect to the area of the second section 42, which can have an influence on its local strength.

Deviating from the embodiment described above, the patterns 16, 18 can also differ and/or an offset of the patterns 16, 18 in only one of the directions, i.e. in the web running direction 20 or perpendicular thereto, can be provided.

However, the patterns 16, 18 can also be introduced into the fiber mat web 12 in such a way that the respective substructures 38 of the patterns are arranged next to one another, ie offset in the web running direction 20 and/or in the width direction (perpendicular to the web running direction 20). This is in 3B to see where the same substructures 38 of the patterns 16, 18 are introduced into the fiber mat web 12 in an offset manner.

In the embodiment according to 3C square structures 38 (pattern 16) are first created, into which circular substructures 38 '(pattern 18) are introduced in order to obtain the target pattern 22.

In the 2 The exemplary embodiment shown of a device according to the invention for producing a fiber mat web 12 differs from that in 1 shown essentially in that the second roller 24b of the first structuring unit 14a forms the second roller 24d of the second structuring unit 14b.

In particular, the structuring device 14 comprises three rollers arranged vertically one above the other, i.e. the axes of rotation 34a, 34b, 34d, 34c of the rollers are arranged one above the other in the vertical direction. The roller 24b, 24d arranged centrally between the first roller 24a of the first structuring unit 14a and the first roller 24c of the second structuring unit 14b is assigned to both the first and the second structuring unit. In addition, the centrally arranged roller 24b, 24d each forms a first press nip 26a and a second press nip 26b with the first roller 24 of the first structuring unit 14a and the first roller 24c of the second structuring unit 14b.

By reducing the number of rollers, a reduction in manufacturing costs and space savings can be achieved. Furthermore, the arrangement shown can be easily integrated into pre- and post-treatment processes of the fiber mat web 12.

It goes without saying that the number of structuring units is not limited to two. For example, configurations are also conceivable in which the structuring device 14 comprises three, four or more structuring units arranged one behind the other in the web running direction 20. In particular, the structuring device 14 can comprise three, four or more rollers 24 arranged one behind the other in the web running direction 20, the surfaces of which have corresponding structuring, so that even more detailed patterns can be produced in the fiber mat web in a simple and cost-effective manner.

Furthermore, it goes without saying that the embodiments of the device can be combined with one another in any way. For example, one is Arrangement conceivable in which the in 1 shown device of in 2 shown is arranged upstream or downstream.

Generating the desired target pattern 22 by a large number of structuring units eliminates the need for expensive, complex structuring of a surface of a single roller 24.

Creating the third pattern 22 in the fiber mat web 12 not only has the advantage that the fiber mat web 12 can be designed to be visually and haptically appealing. The superimposed and successive introduction of two or more patterns according to the invention can also be used to improve the physical properties of the fiber mat web 12 overall. The structuring device 14 can in particular be designed to not only solidify the fiber mat web 12 locally to introduce the patterns, but also to solidify it over the area. This makes it possible, for example, to achieve improved tear resistance of the fiber mat web 12.

Reference symbol list

10

contraption

12

Fiber mat sheet

14

Structuring device

14a

first structuring unit

14b

second structuring unit

16

first pattern (basic pattern)

18

second pattern (basic pattern)

20

Web running direction

22

third pattern (target pattern)

24

roller

24a

first roller of the first structuring unit

24a

second roller of the first structuring unit

24c

first roller of the second structuring unit

24d

second roller of the second structuring unit

26

Pressnip

26a

first press nip

26b

second press nip

30

Carrying device

32

Distance between the first structuring unit and the second structuring unit

34a

Axis of rotation of the first roller of the first structuring unit

34b

Axis of rotation of the second roller of the first structuring unit

34c

Axis of rotation of the first roller of the second structuring unit

34d

Axis of rotation of the second roller of the second structuring unit

36

period

38, 38'

Substructures of the patterns

40

first section of the fiber mat web

42

second section of the fiber mat web

44

third section of the fiber mat web

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2019137667 A1 [0003, 0026]

Claims (15)

Device (10) for producing a fiber mat web (12), in particular a structured and dry-laid tissue paper web or nonwoven web, from a fibrous starting material, the device (10) comprising: a provision device for providing the fibrous starting material; a processing device for low-water processing of the provided starting material; and a forming device for forming a flat fiber mat web (12) from the prepared starting material by a dry forming process, characterized in that the device (10) further comprises a structuring device (14) for structuring the flat fiber mat web (12), wherein the structuring device (14 ) comprises at least a first structuring unit (14a) and a second structuring unit (14b), the first structuring unit (14a) for introducing a first pattern (16) into the fiber mat web (12) and the second structuring unit (14b) for introducing a second pattern (18) are formed in the fiber mat web (12), and wherein the second structuring unit (14b) is arranged behind the first structuring unit (14a) in the web running direction (20), so that by superimposing the first and second patterns (16, 18) a third pattern (22) can be generated in the fiber mat web (12). Device (10) after Claim 1 , characterized in that the first and/or the second structuring unit (14a, 14b) comprises at least one roller (24) which has a structured surface for introducing the respective pattern (16, 18). Device (10) after Claim 2 , characterized in that the structured surface has a hole pattern, a dot pattern, a groove pattern and/or a line pattern, in particular wherein the respective pattern (16, 18) is periodic. Device (10) according to one of the preceding claims, characterized in that the first and/or the second structuring unit (14a, 14b) comprises at least one pair of rollers with a first and a second roller (24a, 24b) which form a press nip (26). form, in particular wherein both structuring units (14a, 14b) comprise a pair of rollers which form a first and a second press nip (26a, 26b). Device (10) according to one of the Claims 1 until 3 , characterized in that the first and second structuring units (14a, 14b) comprise a pair of rollers with a first and a second roller (24a, 24b, 24c, 24d), the second roller (24b) of the first structuring unit (14a). second roller (24d) of the second structuring unit (14b). Device (10) according to one of the preceding claims, characterized in that the first press nip (26a) and the second press nip (26b) are designed differently, in particular wherein different pressing forces are provided in the first and the second press nip (26a, 26b) and /or wherein the nip widths (28) of the first and second press nips (26a, 26b) are different. Device (10) according to one of the preceding claims, characterized in that the structuring device (14) is designed to not only solidify the fiber mat web (12) locally for introducing the patterns, but also to solidify it over the area. Method for producing a fiber mat web (12), in particular a structured and dry-formed tissue paper web or nonwoven web, from a fibrous starting material, in particular with a device (10) according to at least one of the preceding claims, the method comprising: providing the fibrous starting material; low-water processing of the provided starting material; and forming a flat fiber mat web (12) from the prepared starting material by a dry forming process, characterized in that the method further comprises structuring the flat fiber mat web (12) by introducing a first pattern (16) and a second pattern (18), so that a third pattern (22) can be generated. Procedure according to Claim 8 , characterized in that the first pattern (16) and the second pattern (18) can be introduced offset. Procedure according to Claim 8 or 9 , characterized in that the first pattern (16) and the second pattern (18) can be introduced superimposed. Procedure according to one of the Claims 8 until 10 , characterized in that the first pattern (16) and the second pattern (18) can be introduced in such a way that they overlap at least in sections. Procedure according to one of the Claims 8 until 11 , characterized in that the first pattern (16) and the second pattern (18) are the same. Procedure according to one of the Claims 8 until 11 , characterized in that the first pattern (16) and the second pattern (18) differ. Procedure according to one of the Claims 8 until 13 , characterized in that the first pattern (16) and the second pattern (18) each differ from the third pattern (22). Procedure according to one of the Claims 8 until 14 , characterized in that in the structuring step, the fiber mat web (12) can not only be solidified locally to introduce the patterns, but can also be solidified over the area.

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