VACUUM CLEANER FILTER BAG HAVING IMPROVED WELD SEAM STRENGTH

Abstract

The invention comprises a vacuum cleaner filter bag with a bag wall, comprising: a support layer comprising recycled polyethylene terephthalate, rPET; a fine filter layer of a meltblown non-woven fabric comprising polypropylene, PP, PET and/or recycled polypropylene, rPP; and a capacity layer of a non-woven fabric comprising rPET, recycled textile material, TLO, and/or rPP; wherein the bag wall moreover comprises at least one intermediate layer formed of a non-woven fabric or a fibrous web and comprising rPP as a main component; and wherein the at least one intermediate layer is arranged between the support layer and the fine filter layer and/or between the fine filter layer and the capacity layer.

Claims

1. A vacuum cleaner filter bag with a bag wall, comprising: a support layer comprising a recycled polyethylene terephthalate, rPET; a fine filter layer of a meltblown non-woven fabric comprising a polypropylene, PP, a PET and/or a recycled polypropylene, rPP; and a capacity layer of a non-woven fabric comprising a rPET, a recycled textile material, a TLO, and/or an rPP; wherein the bag wall further comprises at least one intermediate layer formed of a non-woven fabric or a fibrous web and comprising an rPP as a main component; and wherein the at least one intermediate layer is arranged between the support layer and the fine filter layer and/or between the fine filter layer and the capacity layer.

2. The vacuum cleaner filter bag according to claim 1, wherein the at least one intermediate layer is made of a staple fibre non-woven fabric or a staple fibre web, or an extrusion non-woven fabric or an extrusion web.

3. The vacuum cleaner filter bag according to claim 1, wherein fibres or filaments of the non-woven fabric or the fibrous web of the at least one intermediate layer have an average diameter of more than 5 μm.

4. The vacuum cleaner filter bag according to claim 1, wherein an air permeability of the at least one intermediate layer is more than 2000 l/m.sup.2/s.

5. The vacuum cleaner filter bag according to claim 1, wherein a grammage of the at least one intermediate layer is between 5 and 50 g/m.sup.2.

6. The vacuum cleaner filter bag according to claim 1, wherein the non-woven fabric or the fibrous web of the at least one intermediate layer comprises a melt flow index of less than 100 g/10 min.

7. The vacuum cleaner filter bag according to claim 1, wherein the at least one intermediate layer is directly adjacent to the fine filter layer.

8. The vacuum cleaner filter bag according to claim 1, wherein a protective layer is directly adjacent to the capacity layer towards an interior of the bag which is made of a non-woven fabric comprising a recycled plastic.

9. The vacuum cleaner filter bag according to claim 8, wherein the protective layer is embodied corresponding to the intermediate layer.

10. The vacuum cleaner filter bag according to claim 1, wherein the support layer is a spunbond of the rPET.

11. The vacuum cleaner filter bag according to claim 1, wherein the non-woven fabric of the at least one intermediate layer comprises bicomponent fibres.

12. A method of manufacturing a vacuum cleaner filter bag, comprising the steps of: providing a non-woven fabric laminate, comprising: a support layer comprising a recycled polyethylene terephthalate, rPET; a fine filter layer of a meltblown non-woven fabric comprising a polypropylene, PP, a PET, and/or a recycled polypropylene, rPP; a capacity layer of a non-woven fabric comprising an rPET, a recycled textile material, a TLO, and/or an rPP; and at least one intermediate layer formed of a non-woven fabric or a fibrous web and comprising an rPP as a main component, wherein the at least one intermediate layer is arranged between the support layer and the fine filter layer and/or between the fine filter layer and the capacity layer; and finishing the non-woven fabric laminate to the vacuum cleaner filter bag.

13. The method according to claim 12, wherein the finishing of the non-woven fabric laminate comprises forming at least one weld seam, and wherein the method further comprises a precompaction of the non-woven fabric laminate in at least one region where the at least one weld seam is formed.

14. The method according to claim 13, wherein the precompaction is accomplished by ultrasonic welding, thermal welding or by pressurization.

15. The method according to claim 13, wherein a sonotrode is arranged, during the precompaction, at the support layer or a side of the laminate located closer to the support layer.

16. A vacuum cleaner filter bag with a bag wall, comprising: a support layer comprising a recycled polyethylene terephthalate, rPET; a fine filter layer of a meltblown non-woven fabric comprising polypropylene, PP, a PET, and/or a recycled polypropylene, rPP; and a protective layer made of a non-woven fabric comprising a recycled plastic; wherein the bag wall further comprises at least one intermediate layer formed of a non-woven fabric or a fibrous web and comprising an rPP as a main component; and wherein the at least one intermediate layer is arranged between the support layer and the fine filter layer and/or between the fine filter layer and the protective layer.

17. A method of manufacturing a vacuum cleaner filter bag, comprising the steps of: providing a non-woven fabric laminate, comprising: a support layer comprising a recycled polyethylene terephthalate, rPET; a fine filter layer of a meltblown non-woven fabric comprising a polypropylene, PP, a PET and/or a recycled polypropylene, rPP; a protective layer made of a non-woven fabric comprising a recycled plastic; and at least one intermediate layer formed of a non-woven fabric or a fibrous web and comprising an rPP as a main component, wherein the at least one intermediate layer is arranged between the support layer and the fine filter layer and/or between the fine filter layer and the protective layer; and finishing the non-woven fabric laminate into a vacuum cleaner filter bag.

18. The vacuum cleaner filter bag according to claim 3, wherein the fibres or filaments of the non-woven fabric or the fibrous web of the at least one intermediate layer have an average diameter between 10 μm to 100 μm.

19. The vacuum cleaner filter bag according to claim 4, wherein the air permeability of the at least one intermediate layer is more than 800 l/m.sup.2/s.

20. The vacuum cleaner filter bag according to claim 11, wherein the biocomponent fibres comprise a core comprising an rPET and an envelope comprising an rPP or vice-versa.

Description

[0074] Further features and advantages of the invention will be illustrated below with reference to the exemplary figures. In the figures:

[0075] FIG. 1 schematically shows the structure of an exemplary vacuum cleaner filter bag; and

[0076] FIG. 2 shows the schematic structure of the bag wall of an exemplary vacuum cleaner filter bag in a cross-section.

[0077] FIG. 1 shows the schematic structure of an exemplary vacuum cleaner filter bag. The filter bag comprises a bag wall 1, a holding plate 2 and an admission port through which the air to be filtered flows into the filter bag. The admission port is here formed by a through-opening 3 in the base plate of the holding plate 2 and a through-opening in the bag wall 1 aligned with it. The holding plate 2 is used for fixing the vacuum cleaner filter bag in a corresponding mounting in a housing of a vacuum cleaner.

[0078] The bag wall 1 comprises a plurality of non-woven fabric layers or a plurality of non-woven fabric and fibrous web layers which overlap each other from the bag's interior to the bag's exterior. The non-woven fabric or fibrous web layers can loosely lie one upon the other or be connected to each other. The connections can be accomplished across the surface (e. g. via spray adhesives), or punctually (e. g. via a calendaring pattern).

[0079] The individual layers can in particular comprise different plastic materials, both among each other and/or within one respective layer.

[0080] The exemplary vacuum cleaner filter bag of FIG. 1 is a so-called flat bag wherein the bag wall comprises an upper side and a bottom side which are connected to each other by a surrounding weld seam. Both the upper side and the bottom side of the flat bag comprise, as mentioned above, a plurality of filter material layers, in particular a plurality of non-woven fabric layers or a plurality of non-woven fabric and fibrous web layers. Both the upper side and the bottom side can in particular be formed of a laminate of a plurality of non-woven fabric layers. However, the invention is not limited to flat bags but can also be applied, for example, to gusset bags or pad bottom bags.

[0081] Advantageously, the holding plate 2 in this example comprises a base plate of a recycled plastic material, for example, recycled polypropylene (rPP) or recycled polyethylene terephthalate (rPET).

[0082] In the operation of such a vacuum cleaner filter bag, the weld seam strength for the surrounding weld seam is of particular importance.

[0083] FIG. 2 illustrates an exemplary structure of the bag wall which leads to an increase of the weld seam strength compared to known vacuum cleaner filter bags.

[0084] FIG. 2 in particular shows a section through the bag wall of an exemplary vacuum cleaner filter bag, for example through the upper side of the flat bag of FIG. 1. Here, the layer 4 is arranged towards the bag's interior, and the layer 8 is arranged at the outer side of the vacuum cleaner filter bag.

[0085] The layer 4 is a protective layer which can be formed of a non-woven fabric of any recycled fibres or filaments. For example, the protective layer can be formed of a non-woven fabric which comprises rPP and/or rPET, or consists thereof. In particular, the protective layer 4 can be a spunbond.

[0086] As a raw material, for example PET waste (e. g. punchings) and so-called bottle flakes, i. e. pieces of ground beverage bottles, can be used. To cover the different colours of the waste, it is possible to colour the recyclate. As a thermal bonding method for the solidification of the spunlaid web into a spunbond, in particular the HELIX® (Comerio Ercole) method is advantageous.

[0087] Adjacent to the protective layer, a capacity layer 5 is arranged. The capacity layer 5 offers high resistance against impact loads and permits a filtering of large dirt particles, a filtering of a significant proportion of small dust particles, and a storage or retention of high amounts of particles, the air being allowed to flow through easily, thus resulting in a low pressure drop with a high particle load. The capacity layer can in particular comprise a fibrous web and/or a non-woven fabric which comprises pulverized and/or fibrous recycled material from the manufacture of textiles (TLO), or consists thereof. The capacity layer 5 can also comprise rPET and/or rPP or consist thereof.

[0088] The capacity layer 5 preferably comprises a basis weight of 5 to 200 g/m.sup.2, in particular of 10 to 150 g/m.sup.2, in particular of 20 to 100 g/m.sup.2, in particular of 30 to 50 g/m.sup.2.

[0089] Towards the exterior of the bag wall, a fine filter layer 6 is adjacent to the capacity layer 5. The fine filter layer 6 is, in this example, an extrusion non-woven fabric, in particular a meltblown non-woven fabric. The fine filter layer 6 can in particular comprise (virgin) polypropylene, bicomponent fibres of (virgin) polypropylene and (virgin) polyethylene terephthalate, and/or bicomponent fibres of (virgin) polypropylene and recycled polypropylene, or consist thereof.

[0090] A fine filter layer 6 serves to increase the filtration performance of the multi-layer filter material by capturing particles which penetrate, for example, the protective layer 4 and/or the capacity layer 5. To further increase the separation performance, the fine filter layer 6 can be preferably charged electrostatically (e. g. by corona discharge or hydro-charging), in particular to increase the separation of particulate matter.

[0091] According to an advantageous embodiment, the fine filter layer 6 has a basis weight of 5 to 100 g/m.sup.2, in particular of 10 to 50 g/m.sup.2, in particular of 10 to 30 g/m.sup.2.

[0092] Grammage (basis weight) is determined according to DIN EN 29073-1: 1992-08.

[0093] The layer arranged in this schematic example at the outermost position is the support layer 8. A support layer (sometimes also referred to as “reinforcement layer”) is here a layer that imparts the required mechanical strength to the multi-layer bond of the filter material. The support layer can in particular be an open, porous non-woven fabric with a light grammage. The support layer 8 can in particular be a spunbond which comprises rPET or consists thereof.

[0094] WO 01/003802 offers an overview of the individual functional layers within multi-layer filter materials for vacuum cleaner filter bags.

[0095] According to an exemplified embodiment of the invention, between the support layer 8 and the fine filter layer 6, an intermediate layer 7 is arranged which is made of a non-woven fabric comprising rPP as a main component. The intermediate layer 7 can be a non-woven fabric layer of a staple fibre non-woven fabric or an extrusion non-woven fabric. It has surprisingly been found that such an intermediate layer essentially improves the weld seam strength of the filter bag. Instead of a non-woven fabric, a fibrous web can also be used for the intermediate layer 7. This is because an intrinsic strength of the intermediate layer is not required.

[0096] A particularly advantageous improvement of the maximum tensile force of the weld seams (here briefly referred to as “weld seam strength”) can be achieved if the grammage of the intermediate layer 7 is between 5 and 50 g/m.sup.2, and simultaneously the average diameter of the fibres or filaments is at least 5 μm, in particular between 10 μm and 100 μm. Such a non-woven fabric is relatively coarse. Air permeability can be at least 4000 l/m.sup.2/s.

[0097] Air permeability is determined according to DIN EN ISO 9237: 1995-12. The air permeability test apparatus FX3300 by Texttest AG can be employed. In particular, a differential pressure of 200 Pa and a test area of 25 cm.sup.2 can be employed.

[0098] The determination of the maximum tensile force can be performed in accordance with DIN EN 29073-3: 1992-08, in particular with a strip of a width of 5 cm.

[0099] The melt flow index of the material of the intermediate layer, in particular the employed rPP, can be less than 100 g/10 min. Thereby, the maximum tensile force of the weld seams can be further increased.

[0100] A further improvement of the weld seam strength can be achieved if welding is performed in two steps. In a first step, in particular one or both material webs which are used for manufacturing the flat bag can be precompacted in the welding region. This precompaction can be accomplished by ultrasonic welding, thermal welding, or by pressurization. In particular, the sonotrode can be placed onto the exterior of the laminate during precompaction, that means be in direct contact with the support layer 8.

[0101] The sonotrodes and anvils used for welding can have a smooth surface. However, it is advantageous for the sonotrode and/or the anvil to comprise a high-low structure for the welding operation, that means that the surface is provided with a relief. For precompaction, a surface smooth on both sides or a lower structuring is advantageous. However, for precompaction, too, the sonotrode and/or anvil employed can comprise a high-low structure, that means the surface is provided with a relief.

[0102] A further, second intermediate layer not shown in the figures can be provided between the fine filter layer 6 and the capacity layer 5. The second intermediate layer can be embodied corresponding to the first intermediate layer 7, but it can also differ from the intermediate layer 7 in one or more features. It is only essential that the second intermediate layer, too, is made of a non-woven fabric or a fibrous web which comprises rPP as a main component. Preferably, the grammage of the second intermediate layer is also between 5 and 50 g/m.sup.2, and simultaneously, the average diameter of the fibres or filaments is at least 5 μm, in particular between 10 μm and 100 μm. The melt flow index of the material of the intermediate layer, in particular the employed rPP, can also be less than 100 g/10 min.

[0103] The capacity layer 5 can also be eliminated according to an alternative, or be replaced by a further intermediate layer or a further fine filter layer.

[0104] To illustrate the effect of intermediate layers of rPP, the following comparative measurements have been made:

TABLE-US-00001 Embodiment in accordance with Variant Comparative Example 1 Comparative Example 2 the invention Material Support layer: Support layer: Support layer: structure rPET spunbond 40 g/m.sup.2 rPET spunbond 40 g/m.sup.2 rPET spunbond 40 g/m.sup.2 Fine filter layer: Fine filter layer: Intermediate layer: PP Meltblown 20 g/m.sup.2 PP Meltblown 40 g/m.sup.2 rPP carded 20 g/m.sup.2 Capacity layer: Capacity layer: Fine filter layer: carded non-woven carded non-woven fabric PP Meltblown 40 g/m.sup.2 fabric with TLO 90 g/m.sup.2 with TLO 90 g/m.sup.2 Intermediate layer: rPP carded 20 g/m.sup.2 Capacity layer: carded non-woven fabric with TLO 90 g/m.sup.2 Welding 2400 W, 4 bar, 260 J, 2400 W, 4 bar, 260 J, 2400 W, 4 bar, 260 J, parameters 70% amplitude 70% amplitude 70% amplitude Maximum Average value of 10 Average value of 10 Average value of 10 tensile measurements: measurements: measurements: force weld 32.9N 44.4N 75.4N seam at 5 cm strip width

[0105] The influence of an optional precompaction will be obvious from the following measurements:

TABLE-US-00002 Material Support layer: Support layer: structure rPET spunbond 50 g/m2 rPET spunbond 50 g/m2 Intermediate layer: Intermediate layer: rPP carded 20 g/m.sup.2 rPP carded 20 g/m.sup.2 Fine filter layer: Fine filter layer: PP Meltblown 20 g/m.sup.2 PP Meltblown 20 g/m.sup.2 Intermediate layer: Intermediate layer: rPP carded 20 g/m.sup.2 rPP carded 20 g/m.sup.2 Capacity layer: Capacity layer: carded non-woven fabric with TLO carded non-woven fabric with TLO 90 g/m.sup.2 90 g/m.sup.2 Welding 2400 W, 4 bar, 260 J, 70% 1. Precompaction with 2400 W, 4 bar parameters amplitude and 200 J, 70% amplitude 2. Welding with 2400 W, 4 bar 260 J, 70% amplitude Maximum Average value of 10 measurements: Average value of 10 measurements: tensile force 75.4N 85.4N weld seam at 5 cm strip width

[0106] It will be understood that features mentioned in the above-described embodiments are not restricted to these special combinations and are also possible in any other combinations. It will be furthermore understood that geometries shown in the figures are only given by way of example and are also possible in any other embodiments.