ASSEMBLY OF A DEVICE, AND METHOD AND DEVICE FOR PRODUCING A COMPOSITE NONWOVEN FABRIC

Description

CROSS REFERENCE TO PRIOR APPLICATIONS

This application is a U.S. National Phase application under 35 U.S. C. § 371 of International Application No. PCT/EP2022/051877, filed on Feb. 21, 2022 and which claims benefit to German Patent Application No. 10 2021 104 974.1, filed on Mar. 2, 2021. The International Application was published in German on Sep. 9, 2022 as WO 2022/184349 A1 under PCT Article 21(2).

FIELD

The present invention relates to an assembly of a device, to a method, and to a device for producing a composite nonwoven fabric having at least two layers.

BACKGROUND

Composite nonwoven fabric with at least two layers is often used as the base material for hygienic wipes. Carded nonwoven lines are often used for producing this composite nonwoven fabric. These regularly comprise at least two cards, hereinafter referred to as “carding units,” which are arranged one behind the other in the production direction of the composite nonwoven fabric. The first carding unit in the direction of production is used to form a first layer of a fiber pile. The second carding unit, viewed in the direction of production, is used to form a second layer of a fiber pile, which is regularly stored on top of the first layer. The fibers of the fibers formed with these carding units regularly have lengths of between 10 mm and 150 mm and are also referred to as “long fibers”.

Viewed in the direction of production, an apparatus for consolidating the two layers is regularly configured downstream of the second carding unit, which can, for example, be configured as a water bonding apparatus. In this apparatus, the fibers of each layer are entangled with one another and the fibers of the two layers are entangled with one another at least over a thickness range adjoining the interface of the two layers so that, after passing through the apparatus for bonding, the two layers are bonded to form a composite nonwoven fabric which can subsequently be fed for further treatment or further processing.

Composite nonwoven fabrics comprising polyester/polypropylene fibers and/or viscose fibers are often used for producing hygiene wipes. The first carding unit in the direction of production then regularly serves to provide a first fiber pile, which can comprise these fibers or mixtures thereof, and the second carding unit in the direction of production serves to provide a second fiber pile, which can also comprise these fibers or mixtures thereof.

The “polyester/polypropylene with viscose material mix” hygiene wipes have good usage properties, such as absorbency and tear resistance. A disadvantage is, however, that these hygiene wipes are not biodegradable due to the polyester/polypropylene content.

There is therefore a need for hygienic wipes that are fully biodegradable. The starting material can be single-layer viscose fiber or composite nonwoven fabric in which both layers consist of viscose long fibers. Viscose fibers are, however, much more expensive and complex to produce than polyester/polypropylene fibers so that the production costs of hygiene wipes increase as the viscose content increases.

There is therefore a desire to replace as much of the viscose as possible with another raw material that is suitable for forming a composite nonwoven fabric with properties required for producing sanitary wipes, is biodegradable, and which is more cost-effective than viscose.

It has been shown that natural fibers such as hemp, flax, cotton, linters or cellulose, the latter also being called “pulp”, with fiber lengths of regularly less than 1 mm to 10 mm, and thus also called “natural short fibers”, are suitable as such raw materials to replace a part of the viscose fibers. Natural short fibers are biodegradable, available in almost unlimited quantities, and can be provided at very cost-effective prices. Pulp has proven to be particularly suitable as a natural short fiber.

Its use in the large-scale industrial production of hygiene wipes has, however, so far met with little acceptance since the production of polyester/polypropylene-with-viscose composite nonwoven fabrics requires the use of two carding units arranged one behind the other in the direction of production. They are not suitable for the production of a viscose-with-pulp composite nonwoven fabric since a carding unit is regularly not suitable for processing natural short fibers.

SUMMARY

An aspect of the present invention is therefore to provide a measure by virtue of which a polyester/polypropylene-with-viscose composite nonwoven fabric suitable for the production of a viscose-with-natural-short-fibers composite nonwoven fabric is provided.

In an embodiment, the present invention provides an assembly of a device for producing a composite nonwoven fabric. The composite nonwoven fabric comprises at least a first layer and a second layer. The assembly is configured to apply natural short fibers to the first layer and is designed so that the assembly can be used interchangeably as an apparatus which applies long fibers in the device.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in greater detail below on the basis of embodiments and of the drawings in which:

FIG. 1 shows a side view of a device belonging to the prior art;

FIG. 2 shows a side view of a first embodiment of a device according to the present invention with an assembly according to the present invention;

FIG. 3 shows a side view of a second embodiment of a device according to the present invention with the assembly according to the present invention;

FIG. 4 shows a side view of a third embodiment of a device according to the present invention with the assembly according to the present invention; and

FIG. 5 shows an example of a stock preparation system for pulp.

DETAILED DESCRIPTION

A device for producing a composite nonwoven fabric comprising at least two layers, which is provided for producing a polyester/polypropylene-with-viscose composite nonwoven fabric, has surprisingly been found to be suitable for producing a viscose-with-natural-short-fibers composite nonwoven fabric when only the second carding unit in the direction of production is replaced by an apparatus for applying natural short fibers to the first layer comprising viscose.

The assembly according to the present invention is accordingly provided for applying natural short fibers, in particular pulp, to a first layer and is configured so that it can be used interchangeably with an apparatus for providing long fibers in the device for producing a composite nonwoven fabric having at least two layers.

In an embodiment of the present invention, the assembly can, for example, comprise a circulating conveyor belt having an upper run. During manufacturing, the upper arm serves as a support for the first layer comprising viscose in an area where the natural short fibers, particularly the pulp, can be applied to the first layer.

The upper run can, for example, have a length corresponding approximately to a production run of a carding unit to be exchanged for the pulp application assembly. Additional means of transferring the layer produced by the first carding unit to the assembly, such as conveyor belts, are then regularly unnecessary, thereby reducing the effort involved in converting the device.

The assembly can, for example, comprise a headbox with which the natural short fibers, in particular pulp of an aqueous dispersion, can be applied to the first layer. It has been shown that with this method, which is also known as “wet-laid,” the second pulp layer can be applied with particularly precisely pre-definable properties, such as thickness of the second layer, areal weight, etc. The second pulp layer can be applied with the same thickness as the first layer. The conveyor belt can then, for example, be designed as a screen belt.

If the assembly comprises an apparatus for consolidating the first layer prior to the application of the natural short fibers, in particular pulp, it can be avoided, for example, that parts of the first layer are dislodged by kinetic energy impacting the first layer when the second layer is stored. This risk exists in particular if the first layer comprises a very fine fiber pile.

The assembly can, for example, also comprise an apparatus for consolidating the natural short fibers, particularly the pulp, after application to the first layer. This allows the second layer to be consolidated immediately in the area of the assembly and the second layer to be connected to the first layer.

It has been shown that apparatuses for bonding composite nonwoven fabrics having at least two layers, wherein the first layer comprises viscose fibers and the second layer comprises natural short fibers, in particular pulp, are particularly suitable if they are configured as water bonding apparatuses.

The method according to the present invention for producing a composite nonwoven fabric having at least two layers, wherein the first layer comprises viscose fibers and the second layer comprises natural short fibers, in particular pulp, with a device comprising two carding units, according to the present invention comprises the following steps:

• • providing a stock preparation system for natural short fibers, in particular for pulp;
  • replacing a carding unit with an assembly for applying pulp;
  • providing the first layer via a carding unit, wherein the first layer comprises viscose; and
  • providing the second layer via the assembly, wherein the second layer comprises pulp.

With regard to the biodegradability of the process product, the first layer can, for example, comprise exclusively viscose and the second layer can, for example, comprise exclusively natural short fibers, in particular exclusively pulp.

The present invention also relates to a device for producing a composite nonwoven fabric having at least two layers, the device comprising an assembly having the features described above. According to the present invention, this device is modularly designed so that the assembly can be used interchangeably for a carding unit. Due to the modular design, the device can easily be converted between a production of a composite nonwoven fabric having at least two layers, each comprising long fibers, and a device for producing a composite nonwoven fabric having at least two layers, one layer comprising long fibers and the other comprising short fibers, in particular one comprising viscose fibers and the other comprising pulp.

The present invention will be further illustrated below with reference to the drawings.

The device designated 100 in FIG. 1 and belonging to the prior art comprises a production line 1 which, viewed in a production direction 2, comprises in succession a first carding unit 3 for forming a first layer 4, a second carding unit 5 for forming a second layer 6, and a compacting and bonding apparatus 7 for compacting and bonding the first layer 4 and the second layer 6 to form a composite nonwoven fabric 8, a dryer 9 for drying the composite nonwoven fabric 8, and a winding apparatus 10 for winding up the composite nonwoven fabric 8.

The first and second carding units 3, 5, which have first and second production lengths 11, 12, are each for providing a layer comprising long fibers comprising, for example, polyester/polypropylene fibers or viscose fibers.

The compacting and bonding apparatus 7 comprises a plurality of deflection rollers 13 partially wrapped by the first and second layers 4, 6 so that the two layers are compacted. A plurality of water jet apparatuses 14 are further provided to act against the outwardly facing surfaces of the first and second layers 4, 6 in areas where the first and second layers 4, 6 wrap around the deflection rollers, thereby intertwining the fibers of the two layers 4, 6 with one another and also with one another at least in the adjacent area.

The dryer 9 downstream of the compacting and bonding apparatus 7 in the production direction 2 is designed as a through-flow dryer and comprises a drum 15 around which the composite nonwoven fabric 8 is partially wrapped during manufacturing.

The embodiment of a device 200 according to the present invention shown in FIG. 2 again comprises a production line 1 and differs from the prior art device 100 in that an assembly 16 is provided in place of the second carding unit 5 in the production line 1. In order to avoid repetition, reference is accordingly made to the explanations for FIG. 1 with regard to the components and features which correspond to those of the prior art device 100, and the same reference numbers are used in FIG. 2 as in FIG. 1.

The assembly 16 is here provided for applying a second layer of pulp 17, which is mentioned as representative of natural short fibers in the described embodiment example, to the first layer 4 and is configured so that it can be integrated into the production line 1 in exchange for an apparatus for providing long fibers, in the embodiment example shown in exchange for the second carding unit, and can thus be used in the device.

To this end, in the embodiment of the device 200 shown in FIG. 2, the assembly 16 comprises a circulating conveyor belt 18 with an upper run 19. It has a length 20 corresponding approximately to the second production length 12 of the second carding unit 5 so that the first layer 4 can be transferred from the first carding unit 3 to the upper trunk 19 without any auxiliary devices.

Viewed in the production direction 2, in the area where the first layer 4 is transferred to the upper run 19, a first apparatus 21 for consolidating the first layer 4 is provided, which is here configured as a water jet bonding apparatus.

Continuing in the production direction 2, a headbox 22 is provided via which the pulp 17 can be applied in an aqueous dispersion to the first layer 4. Following the area of this application, and continuing in the production direction 2, is a second apparatus 23 for bonding the pulp 17 after application to the first layer 4. A water intake 24 is provided below the first run 19 for collecting and discharging water of the dispersion and, if the second apparatus 23 for bonding the short fibers is a hydroentanglement apparatus, water discharged therefrom.

The first embodiment of the device 200 according to the present invention shown in FIG. 2 comprises a single first carding unit 3 and a single assembly 16 and is thus provided for producing a composite nonwoven fabric 8 having a single first layer 4 comprising in particular viscose fibers and a single second layer 6 comprising in particular pulp.

The second embodiment of a device 300 shown in FIG. 3, which has an assembly 16, differs from the device 200 only in that, viewed in the production direction 2, a further carding unit 25 is provided upstream of the first carding unit 3, the structure and mode of operation of which corresponds to the first carding unit 3.

To avoid repetition, please again refer to the reference numbers used in FIGS. 1 and 2 and their descriptions.

The device 300 is used for producing a three-layer composite nonwoven fabric 26, which may comprise the following layers: a first layer 4 comprising long fibers, in particular cellulosic fibers, a second layer 27 also comprising long fibers, in particular cellulosic fibers, and a third layer 6′ comprising in particular pulp.

The third embodiment of a device 400 shown in FIG. 4, which has an assembly 16, differs from the device 200 only in that, viewed in the production direction 2, a further carding unit 25′ is provided downstream of the assembly 16, the structure and mode of operation of which corresponds to the first carding unit 3.

To avoid repetition, please again refer to the reference numbers used in FIGS. 1, 2 and 3 and their descriptions.

The device 400 is used for producing a three-layer composite nonwoven fabric 26, which may comprise the following layers: a first layer 4 comprising long fibers, in particular cellulosic fibers, a second layer 6 comprising in particular pulp, and a third layer 27′ also comprising long fibers, in particular cellulosic fibers.

It is understood that devices are also conceivable which comprise further carding units and/or assemblies for applying pulp. The carding units and assemblies for applying pulp can also be arranged in other sequences with respect to the production direction 2.

In the embodiments shown in FIGS. 2, 3 and 4, the assembly 16 comprises a headbox 22 which is designed to apply the pulp in an aqueous dispersion to the first layer. A stock preparation system for the pulp may have the stock preparation 28 shown schematically in FIG. 5.

Via a conveying device 29, pulp portions 30 are added to a pulper 31 and dissolved therein in water, which is supplied to the pulper 31 via a supply line 32. Via a conduit 33, the dissolved pulp is fed to a vat 36 via a pump 34 while supplying separate water via a bypass conduit 35. Further dilution takes place therein by supplying additional water via a supply line 37. Via a conduit 38, the aqueous dispersion of the pulp is conveyed to the headbox 22 via a pump 39 with further addition of water via a bypass conduit 40. Water collected by water intake 24 and, if necessary, extracted by a water jet bonding apparatus with the aid of a pump 51, is collected by a reservoir 42 and supplied to the pulp dilution process by a pump 43 via a return supply line 44. A branch 45 is provided via which the pulp dispersion supplied to the headbox 22 by the pump 39 can be additionally diluted.

The present invention is not limited to embodiments described herein; reference should be had to the appended claims.

LIST OF REFERENCE NUMERALS

• • 100 prior art device
  • 200 device
  • 300 device
  • 400 device
  • 1 production line
  • 2 production direction
  • 3 first carding unit
  • 4 first layer
  • 5 second carding unit
  • 6 second layer
  • 6′ third layer
  • 7 compacting and bonding apparatus
  • 8 composite nonwoven fabric
  • 9 dryer
  • 10 winding apparatus
  • 11 first production length
  • 12 second production length
  • 13 deflection roller
  • 14 water jet apparatuses
  • 15 drum
  • 16 assembly
  • 17 pulp
  • 18 conveyor belt
  • 19 upper run
  • 20 length
  • 21 first apparatus
  • 22 headbox
  • 23 second apparatus
  • 24 water intake
  • 25 further carding unit
  • 25′ further carding unit
  • 26 three-layer composite nonwoven fabric
  • 26′ three-layer composite nonwoven fabric
  • 27 second layer
  • 27′ third layer
  • 28 stock preparation
  • 29 conveying device
  • 30 pulp portions
  • 31 pulper
  • 32 supply line
  • 33 conduit
  • 34 pump
  • 35 bypass line
  • 36 vat
  • 37 supply line
  • 38 conduit
  • 39 pump
  • 40 bypass conduit
  • 41 pump
  • 42 reservoir
  • 43 pump
  • 44 return supply line
  • 45 branch