Assembly of a device, and method and device for producing a composite nonwoven fabric

Abstract

The invention relates to an assembly of a device for producing a composite nonwoven fabric comprising at least two layers, said assembly being provided in order to apply natural short fibers, in particular pulp (17), onto a first layer (4) and being designed to be usable as a substitute for a device (carding unit 5) in order to provide long fibers in the device.

Description

[0001] The invention relates to an assembly of a device, a method and a device for producing a composite nonwoven web with at least two layers.

[0002] The base material for hygiene wipes is often composite nonwoven webs with at least two layers. These composite webs are frequently produced using carding machines. These machines typically include at least two carding units, hereinafter referred to as "carding units," arranged one behind the other in the production direction of the composite nonwoven web. The first carding unit in the production direction forms the first layer of fibers. The second carding unit, viewed in the production direction, forms the second layer of fibers, which is typically laid on top of the first layer. The fibers produced by these carding units are typically between 10 mm and 150 mm long and are also referred to as "long fibers."

[0003] Viewed in the direction of production, a device for consolidating the two layers is regularly arranged behind the second carding unit. This device can, for example, be a water jet bonding unit. In this unit, the fibers of each layer are intertwined, and at least over a thickness zone adjacent to the interface between the two layers, the fibers of the two layers are swirled together. This results in the two layers being bonded together to form a composite nonwoven web after passing through the bonding unit, which can then be further processed or manufactured.

[0004] Nonwoven fabrics containing polyester / polypropylene fibers and / or viscose fibers are frequently used in the production of hygiene wipes. The first carding unit in the production direction is typically used to provide a first layer of fibers, which may contain these fibers or mixtures thereof. The second carding unit in the production direction is used to provide a second layer of fibers, which may also contain these fibers or mixtures thereof.

[0005] While the hygiene wipes made from a "polyester / polypropylene-viscose material mix" exhibit good performance characteristics such as absorbency and tear resistance, a disadvantage is that these wipes are not biodegradable due to the polyester / polypropylene content.

[0006] There is therefore a need for hygiene wipes that are completely biodegradable. Single-layer viscose fiber webs or composite nonwoven webs, in which both layers consist of long viscose fibers, are suitable starting materials. However, viscose fibers are significantly more expensive and complex to produce than polyester / polypropylene fibers, so the production costs of hygiene wipes increase with a higher viscose content.

[0007] Therefore, efforts are being made to replace as large a proportion of viscose as possible with another raw material that is suitable for forming a composite nonwoven web with the properties required for the production of hygiene wipes, is biodegradable and more cost-effective than viscose.

[0008] It has been shown that natural fibers such as hemp, flax, cotton, linters, or cellulose (also called pulp), with fiber lengths regularly ranging from less than 1 mm to 10 mm and thus also referred to as "natural short fibers," are suitable as raw materials to replace a portion of viscose fibers. Natural short fibers are biodegradable, available in virtually unlimited quantities, and very cost-effective to produce. Cellulose has proven particularly suitable as a natural short fiber.

[0009] However, its use in the large-scale industrial production of hygiene wipes has so far found little acceptance, as the production of polyester / polypropylene-with-viscose composite nonwoven webs requires the use of two carding units arranged one behind the other in the production direction. These are not suitable for producing a viscose-with-cellulose composite nonwoven web, as a single carding unit is generally not suitable for processing natural short fibers.

[0010] A machine for producing a composite nonwoven web is known from publication WO 2004 / 063 451 A1. The machine has a headbox. Furthermore, the machine has a carding unit.

[0011] The invention is therefore based on the objective of specifying a measure by which a material suitable for the production of a polyester / polypropylene-with-viscose composite nonwoven web is suitable for the production of a viscose-with-natural-short-fiber composite nonwoven web.

[0012] This problem is solved by the assembly described in claim 1, by a method described in claim 7 and by a device described in claim 11 for producing a composite nonwoven web.

[0013] Surprisingly, it has been shown that a device for producing a composite nonwoven web with at least two layers, intended for producing a polyester / polypropylene-with-viscose composite nonwoven web, is suitable for producing a viscose-with-natural-short-fiber composite nonwoven web if only the second carding unit in the production direction is replaced by a device for applying natural short fibers to the first viscose-comprising layer.

[0014] The assembly according to the invention is accordingly designed for applying natural short fibers, in particular cellulose, to a first layer and is designed in such a way that it can be used in place of a device for providing long fibers in the apparatus for producing a composite nonwoven web with at least two layers.

[0015] In a particularly preferred embodiment, the assembly comprises a circulating conveyor belt with an upper run. The latter serves during production as a support for the first, viscose-containing layer in an area where the natural short fibers, in particular the cellulose, can be applied to the first layer.

[0016] Preferably, the upper section has a length approximately corresponding to the production length of a carding unit that is to be exchanged for the pulp application assembly. Additional measures for transferring the layer produced by the first carding unit to the assembly, such as conveyor belts, are then generally unnecessary, thus reducing the effort associated with retooling the device.

[0017] The assembly preferably comprises a headbox with which natural short fibers, in particular cellulose from an aqueous dispersion, can be applied to the first layer. It has been shown that this process, also known as "wet-laid," allows the application of the second cellulose layer with particularly precisely predefined properties, such as the thickness of the second layer, basis weight, etc. The conveyor belt is then preferably designed as a wire mesh belt.

[0018] If, as is preferred, the assembly includes a device for consolidating the first layer before the application of the natural short fibers, especially cellulose, it can be prevented, for example, that parts of the first layer are detached by kinetic energy acting on the first layer when the second layer is laid down. This risk is particularly high if the first layer consists of a very fine fiber nap.

[0019] It is also preferred if the assembly includes a device for consolidating the natural short fibers, especially the cellulose, after application to the first layer. This allows for immediate consolidation of the second layer and bonding of the second layer to the first layer within the assembly area.

[0020] It has been shown that equipment for consolidating composite nonwoven webs with at least two layers, wherein the first layer comprises viscose fibers and the second layer comprises natural short fibers, in particular cellulose, is particularly suitable when designed as water jet consolidation equipment.

[0021] The inventive method for producing a composite nonwoven web with at least two layers, wherein the first layer comprises viscose fibers and the second layer comprises natural short fibers, in particular cellulose, with a device comprising two carding units, comprises the following steps according to the invention: Providing a stock preparation system for natural short fibers, in particular for cellulose; replacing a carding unit with an assembly for applying cellulose; providing the first layer by means of a carding unit, wherein the first layer comprises viscose; providing the second layer by means of the assembly, wherein the second layer comprises cellulose.

[0022] With regard to the biodegradability of the process product, it is particularly preferred if the first layer comprises exclusively viscose and the second layer comprises exclusively natural short fibers, in particular exclusively cellulose.

[0023] The invention also relates to a device for producing a composite nonwoven web with at least two layers, comprising an assembly with the features described above. According to the invention, this device is modularly designed such that the assembly can be used in place of a carding unit. Due to its modular design, the device can be easily converted between producing a composite nonwoven web with at least two layers, each comprising long fibers, and producing a composite nonwoven web with at least two layers, one of which comprises long fibers and the other short fibers, in particular one comprising viscose fibers and the other cellulose.

[0024] The invention will be further clarified below with reference to the drawings. They schematically show: Fig. 1 shows a prior art device in a side view; Fig. 2 shows a side view of a first embodiment of a device according to the invention with an assembly according to the invention; Fig. 3 shows a side view of a second embodiment of a device according to the invention with the assembly according to the invention; Fig. 4 shows a side view of a third embodiment of a device according to the invention with the assembly according to the invention; and Fig. 5 shows the structure of an embodiment of a pulp preparation system.

[0025] The in Fig. 1The prior art device designated by 100 comprises a production line 1, which, viewed in a production direction 2, includes in succession a first carding unit 3 for forming a first layer 4, a second carding unit 5 for forming a second layer 6, a compacting and consolidation unit 7 for compacting and consolidating the first layer 4 and the second layer 6 to form a composite nonwoven web 8, a dryer 9 for drying the composite nonwoven web 8, and a winding unit 10 for winding the composite nonwoven web 8.

[0026] The first and second carding units 3, 5, which have first and second production lengths 11, 12, each serve to provide a layer comprising long fibers, which include, for example, polyester / polypropylene fibers or viscose fibers.

[0027] The compacting and consolidation device 7 comprises a plurality of deflecting rollers 13, which are partially enclosed by the first and second layers 4, 6, so that the two layers are compacted. Furthermore, a plurality of water jet devices 15 are provided, which act against the outwardly facing surfaces of the first and second layers 4, 6 in areas where the first and second layers 4, 6 encircle the deflecting rollers, thus entangling the fibers of the two layers 4, 6 with each other and, at least in the adjacent area, also with each other.

[0028] The dryer 9 following the compacting and consolidation device 7 in production direction 2 is designed as a flow-through dryer and comprises a drum 15 which is partially enclosed by the composite nonwoven web 8 during production.

[0029] The in Fig. 2The illustrated embodiment of a device 200 according to the invention again comprises a production line 1 and differs from the prior art device 100 by an assembly 16 which is provided in place of the second carding unit 5 in the production line 1. Accordingly, to avoid repetition, reference is made to the descriptions of the components and features that correspond to those of the prior art device 100. Fig. 1 referred and in Fig. 2 the same reference figures as in Fig. 1 used.

[0030] The assembly 16 is designed to apply a second layer of cellulose 17, which in the described embodiment is referred to as representing natural short fibers, to the first layer 4 and is designed in such a way that it can be integrated into the production line 1 and thus used in the device in place of a device for providing long fibers, in the illustrated embodiment in place of the second carding unit.

[0031] For this purpose, assembly group 16 includes the one in Fig. 2 In the illustrated embodiment of the device 200, a circulating conveyor belt 18 with an upper section 19 is used. It has a length 20 which corresponds approximately to the production section 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 section 19 without further aids.

[0032] In production direction 2, in the area of ​​the transfer of the first layer 4 to the upper section 19, a device for solidifying the first layer 4 is provided, which is designed as a water jet solidification device.

[0033] In production direction 2, a headbox 22 is provided, by means of which the pulp 17 in an aqueous dispersion can be applied to the first layer 4. In the area of ​​application and a second device 23 for consolidating the pulp 17 after application to the first layer 4, a water absorption unit 24 is provided below the first strand 19, which collects and removes water from the dispersion as well as – if the device 23 for consolidating the short fibers is a water jet consolidation device – water released by it.

[0034] The in Fig. 2The illustrated embodiment 100 of the device according to the invention comprises a single first carding unit 3 and a single assembly 16 and is thus intended for the production of a composite nonwoven web 8 which has a single first layer 4, in particular comprising viscose fibers, and a single second layer 6, in particular comprising cellulose.

[0035] The in Fig. 3 The second embodiment of a device 300 shown, 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 in front of the carding unit 3, the structure and function of which corresponds to the first carding unit 3.

[0036] Again, to avoid repetition, refer to the following: Fig. 1 and 2 References were made to the reference numbers used and their descriptions.

[0037] The device 300 serves to produce a three-layer composite nonwoven web 26, which may comprise the following layers: a first layer 4 comprising long fibers, in particular cellulose fibers, a second layer 27 also comprising long fibers, in particular cellulose fibers, and a third layer 6' comprising in particular cellulose.

[0038] The in Fig. 4 The third embodiment of a device 400, which has an assembly 16, shown here, differs from the device 200 only in that, viewed in the production direction 2, a further carding unit 25' is provided behind the assembly 16, the structure and function of which corresponds to the first carding unit 3.

[0039] Again, to avoid repetition, refer to the following: Fig. 1 , 2 and 3 References were made to the reference numbers used and their descriptions.

[0040] The device 400 serves to produce a three-layer composite nonwoven web 26, which may comprise the following layers: a first layer 4 comprising long fibers, in particular cellulose fibers, a second layer 6 comprising in particular cellulose, and a third layer 27' also comprising long fibers, in particular cellulose fibers.

[0041] It is understood that devices are also conceivable which include further carding units and / or assemblies for applying pulp. The carding units and assemblies for applying pulp can also be arranged in different sequences with respect to production direction 2.

[0042] In the Fig. 2 , 3 and 4In the illustrated embodiments, the assembly 16 comprises a headbox 22 designed such that the pulp can be applied to the first layer in an aqueous dispersion. A stock preparation system for the pulp can be the one described in Fig. 5The stock preparation process 28 is schematically represented as follows: By means of a conveying device 29, portions of pulp 30 are added to a pulper 31 and dissolved in water, which is supplied to the pulper 31 via a supply line 32. Via a line 33, the dissolved pulp is conveyed by a pump 34, with the addition of separate water, through a bypass line 35 to a vat 36. In this vat, further dilution takes place by the addition of more water via a supply line 37. Via a line 38, the aqueous dispersion of the pulp is conveyed by a pump 39, with the addition of further water, through a bypass line 40 to the headbox 22. Water collected from the water intake 24 and, if necessary, extracted by a water jet compaction device using a pump 51, is collected from a reservoir 42 and, by means of a pump 43, is fed back to the pulp dilution process via a return line 44.A branch 45 is provided, by means of which the pulp dispersion supplied to the headbox 22 by means of the pump 39 can be further diluted. Reference symbol list:

[0043] 100, 200, 300, 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 consolidation unit 8 Composite nonwoven web 9 Dryer 10 Winding unit 11 First production length 12 Second production length 13 Deflection roller 14 Water jet devices 15 Drum 16 Assembly 17 Pulp 18 Conveyor belt 19 Upper run 20 Length 22 Headbox 23 Equipment 24 Water absorption 25 Additional carding unit 25' Additional carding unit 26 Composite nonwoven web 26' Composite nonwoven web 27 Second layer 27' Third layer 28 Stock preparation 29 Conveying device 30 Pulp portions 31 Pulper 32 Feed line 33 Line 34 Pump 35 Bypass line 36 Tub 37 Feed line 38 Feed line 39 Pump 40 Bypass line 41 Pump 42 Reservoir 43 Pump 44 Return line 45 Branch

Claims

1. Assembly (16) of a modular device (200, 300, 400) for producing a composite nonwoven web (8) with at least two layers (4, 6), characterized in that the assembly (16) is provided for the application of natural short fibres, in particular pulp (17) to a first layer (4) and is designed in such a way that it can be used as an alternative for a device for providing long fibres in the device.

2. Assembly according to Claim 1, characterized in that the assembly comprises a circulating conveyor belt (18) with an upper strand (19).

3. Assembly according to Claim 2, characterized in that the upper strand (19) has a length (20) which corresponds approximately to a production line (12) of the device for providing long fibres.

4. Assembly according to one of Claims 1 to 3, characterized in that the assembly (16) comprises a headbox (22), by means of which natural short fibres, in particular pulp (17) in an aqueous dispersion can be applied to the first layer (4).

5. Assembly according to one of Claims 1 to 4, characterized in that the assembly (16) comprises a device (23) for consolidating the natural short fibres, in particular the pulp (17) after the application to the first layer (4).

6. Assembly according to Claim 5, characterized in that at least one of the devices (23) for consolidating is designed as a hydroentanglement device.

7. Method for producing a composite nonwoven web (8, 26) with at least two layers (4, 6), wherein the first layer (4) comprises long fibres and the second layer (6) comprises natural short fibres, in particular pulp, with a device comprising two carding units (3, 5), with the following steps: - providing stock preparation for natural short fibres, in particular for pulp; - replacing a carding unit (5) with an assembly (16) for applying pulp; - providing the first layer (4) by means of a carding unit (3); - providing the second layer (6) by means of the assembly (16).

8. Method according to Claim 7, characterized in that the first layer comprises viscose.

9. Method according to Claim 7 or 8, characterized in that the second layer comprises natural short fibres, in particular pulp (17).

10. Method according to Claims 8 and 9, characterized in that the first layer comprises exclusively viscose and the second layer comprises exclusively pulp.

11. Device (200, 300, 400) for producing a composite nonwoven web (8, 26) with at least two layers (4, 6), with an assembly (16) according to one of Claims 1 to 6, characterized in that the device (200, 300, 400) is modularly designed in such a way that the assembly (16) can be used as an alternative for a device for providing long fibres, in particular as an alternative for a carding unit (5).

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