EP2311360B1 - Vacuum cleaner filter bag - Google Patents

Description

The invention relates to a vacuum cleaner filter bag with a bag wall. The invention particularly relates to a disposable filter bag.

Nonwoven fabric vacuum cleaner bags typically have a bag wall made up of multiple layers of filter material. The filter material layers may be, for example, layers of filter paper or nonwoven fabric. In order to achieve the desired properties with regard to separation efficiency, dust storage capacity (capacity) and mechanical strength, different filter material layers are combined. The different filter material layers can be connected to each other or lie loosely on each other. A compound of the layers can be done for example by gluing, welding (calendering) or needling. A multilayer filter bag is for example from the US 4,589,894 known.

The individual filter material layers can have different functions. For example, protective layers, capacitance layers, fine filter layers and reinforcing layers can be combined. As a protective or reinforcing layers are thermally bonded filament spunbonded nonwovens ( EP 0 161 790 ), thermally bonded nonwoven fabrics ( US 5,647,881 ), Networks ( EP 2 011 556 or EP 2 011 555 ) or perforated films ( EP 1 795 248 ) used. The fine filter layers used are microfiber spunbonded nonwovens (eg meltblown nonwovens) (see, for example, US Pat. EP 0 161 790 ). Nanofiber webs have been proposed as Feinstfilterlagen ( DE 199 19 809 ). Coarse filter layers (capacitance layers) can be made, for example, of nonwoven fabrics (carded or aerodynamically laid) or filamentviasives ( EP 0 960 645 ) or of loose staple fibers ( DE 10 2005 059 214 ) consist. Foam has also been proposed as a material for capacity layers ( DE 10 2004 020 555 ).

From the DE 74 24 655 is a dust filter consisting of two layers known, wherein a layer thereby has a very high air permeability and carrier function. The carrier material is paper with high air permeability. The second layer consists of a non-woven, ie of loose and non-solidified fibers.

From the DE 195 44 790 For example, a multi-ply vacuum cleaner bag is known having at least one layer responsible for the particle capture activity. The DE 195 44 790 also claims that if this active layer was strong enough to withstand the stresses of manufacture and use, further layers could be dispensed with.

According to the teaching of DE 195 44 790 However, this active layer has a basis weight of less than 20 g / m ² and a fiber diameter of about 1 micron. With this grammage and fineness, however, a sufficiently stable material can not actually be produced. In operation, bags of such a material would rupture immediately, so that in fact the vacuum cleaner bags known from this document are always multi-layered.

The production of multi-layer vacuum cleaner filter bag from several nonwoven fabric layers, however, is costly because production equipment for a variety of processes for nonwoven fabric production are needed.

Therefore, the object underlying the present invention is to provide a vacuum cleaner filter bag, on the one hand has a sufficient Abscheideleistung and on the other hand can be produced inexpensively. This object is achieved by a vacuum cleaner filter bag according to claim 1.

The invention provides a vacuum cleaner filter bag having a bag wall, the bag wall comprising precisely one nonwoven fabric layer in the form of a melt-spun microfiber nonwoven layer, and having the features contained in claim 1.

The present inventors have found that it is possible to produce a vacuum cleaner filter bag having just one nonwoven fabric layer in the form of a melt-spun microfiber nonwoven layer, ie, a nonwoven fabric layer of melt spun microfiber nonwoven fabric having sufficient separation performance. Since exactly one nonwoven fabric layer and not several nonwoven fabric layers are provided for the bag wall, no different processes for the production of nonwoven fabric are required and a connection of different nonwoven fabric layers can be dispensed with. As a result, the vacuum cleaner filter bag can be produced more cost-effectively than multi-layer vacuum cleaner filter bags.

The term "nonwoven" is defined as ISO standard IS09092: 1988 or CEM standard EN29092 used. In particular, the terms nonwoven fabric or nonwoven and nonwoven fabric in the field of production of nonwovens such follows each other delimited and to understand so in the sense of the present invention. To produce a nonwoven fabric fibers and / or filaments are used. The loose or loose and still unbound fibers and / or filaments are referred to as fleece or nonwoven web. By means of a so-called non-woven binding step, such a nonwoven fabric finally forms a nonwoven which has sufficient strength to be wound into rolls, for example. In other words, a nonwoven fabric is self-supporting by the solidification. (Details on the use of the definitions and / or methods described herein can also be found in the standard work "). Nonwovens ", W. Albrecht, H. Fuchs, W. Kittelmann, Wiley-VCH, 2000 , remove.)

The nonwoven layer corresponds to a layer of a nonwoven fabric which is an extrusion nonwoven fabric, namely a melt spun microfiber spunbonded fabric ("meltblown" nonwoven fabric).

The nonwoven layer according to the invention is a melt spun microfiber spunbonded nonwoven layer.

The bag wall comprises exactly one filter-active layer, which corresponds exactly to a filter-active layer of the nonwoven fabric layer. As a filter-active layer here for the filtering of the air stream to be filtered relevant location is referred to. The bag wall may also comprise a net. The net can serve for the aesthetic design, for example for color design, of the filter bag. The net can also serve to improve the stability of the filter bag. The network may be, for example, an extruded net or a woven net. The mesh may have a mesh size of at least 1 mm, in particular at least 3 mm.

The bag wall may consist of a nonwoven layer in the form of a melt-spun microfiber nonwoven layer. In other words, the vacuum cleaner filter bag can be a single-layered filter bag, with the single layer corresponding to the nonwoven layer, ie the layer of melt-spun microfiber nonwoven fabric. In particular, no support layer or reinforcing layer is provided for the nonwoven fabric layer in this case. In other words, the nonwoven layer can be designed to withstand the usual stresses of manufacture and use.

The nonwoven fabric is a calendered nonwoven, in particular a thermally or ultrasonically calendered nonwoven. For thermal calendering, the initially unconsolidated web can be passed between two rolls, of which at least one of the fibers is heated to the melting temperature of the web forming fibers. At least one of the Calender rolls can have elevations. As a result, melt zone areas or weld points can be formed.

Ultrasonic calendering or ultrasonic solidification is based on the conversion of electrical energy into mechanical vibration energy. This hardening horns are put into vibration, wherein the fibers are softened at the intersection points in the fleece at the vibration points and welded together. As a result, welds can be formed.

The welds themselves may be formed in different geometries. Thus, punctiform, linear, star-shaped, circular, elliptical, square or bar-shaped welded joints can be formed.

The pressing surface portion of the calendered nonwoven fabric is 3% to 50%, in particular 10% to 30%. This means that a roller engraving used for calendering the nonwoven fabric has a pressing surface portion of 3% to 50%, in particular 10% to 30%.

The nonwoven fabric has a number density of weld points of 5 / cm ² to 50 / cm ² , in particular 15 / cm ² to 40 / cm ² , on. The number density is referred to here as the number of spot welds per unit area.

Such a calendered nonwoven fabric may have sufficient strength for use as a bag wall of a vacuum cleaner filter bag.

The welds or welds can be evenly distributed, in particular at equal intervals, or even unevenly over the entire surface of the bag wall.

The welds may be disposed on the nonwoven fabric in the machine direction or at an angle greater than 0 ° and less than 180 ° to the machine direction. In particular, the welds can also be arranged transversely to the machine direction, ie at an angle of 90 ° to the machine direction.

The nonwoven fabric layer has a basis weight of 30 g / m ² to 200 g / m ² , in particular 40 g / m ² to 150 g / m ² , in particular 120 g / m ² .

The nonwoven fabric layer has a maximum machine direction tensile force of greater than 40N, especially greater than 60N. It may also have a maximum tensile force in the transverse direction of more than 30 N, in particular more than 50 N.

The thickness of the nonwoven fabric layer may be between 0.2 mm and 1 mm, in particular between 0.4 mm and 0.8 mm.

The nonwoven fabric layer can have an air permeability of from 40 l / (m ² s) to 500 l / (m ² s), in particular from 50 l / (m ² s) to 300 l / (m ² s), in particular of 80 l / ( m ² s) to 200 l / (m ² s).

The penetration of the nonwoven layer may be less than 60%, in particular less than 50%, in particular less than 15%.

As a material for the nonwoven layer fundamentally different plastics come into question. The material may be a polymer, in particular polypropylene, and / or polyester and / or a biodegradable plastic, in particular PLA (polylactic acid, polylactide) and / or polycaprolactone (PCL). The nonwoven layer can only consist of plastic, in particular of biodegradable plastic.

Biodegradable plastics can be removed from the environment through biodegradation and fed into the mineral material cycle. In particular, biodegradable plastics refer to plastics that meet the criteria of the European standards EN 13432 and / or EN 14995.

Biodegradable plastics, which can be processed into nonwovens, for example, from the US 6,207,601 and the EP 0 885 321 known.

The nonwoven layer can be electrostatically charged. The fibers may be electrostatically charged prior to solidification and / or the nonwoven fabric, ie after solidification.

The nonwoven layer can be electrostatically charged by a corona process. In doing so, the web is centered in an approximately 3.8 cm (1.5 inches) to 7.6 cm (3 inches) wide area between two DC voltage electrodes for corona discharge. In this case, one of the electrodes can have a positive DC voltage of 20 to 30 kV while the second electrode has a negative DC voltage of 20 to 30 kV. Alternatively or additionally, the nonwoven layer may be formed by a method according to the teaching of US 5,401,446 be electrostatically charged.

The vacuum cleaner filter bag may be a flat bag. Alternatively, the vacuum cleaner filter bag may also be a block bottom bag.

The vacuum cleaner filter bag may include an inflow port through which the air to be cleaned flows into the filter bag. The filter bag may further comprise a holding plate, which serves to fix the vacuum cleaner filter bag in a chamber of a vacuum cleaner, and is arranged in the region of the inflow opening. The retaining plate can in particular be made of a plastic. The holding plate can be connected to the bag wall and have a through hole in the region of the inflow opening.

The bag wall may include a front and a back, which are interconnected by a circumferential weld. The front and back can be rectangular, square or circular. The front and back may consist of a nonwoven fabric layer described above.

The vacuum cleaner filter bag may be a disposable vacuum cleaner bag.

The abovementioned parameters can be adapted in particular to the size and / or the intended use of the vacuum cleaner filter bag.

Fig. 1

schematisch den Aufbau eines beispielhaften Staubsaugerfilterbeutels;

Fig. 2

einen Querschnitt durch einen beispielhaften Staubsaugerfilterbeutel; und

Fig. 3

schematisch einen Ausschnitt der durchströmbaren Fläche der Beutelwand eines beispielhaften Staubsaugerfilterbeutels.

The invention will be described in more detail below with reference to examples and figures. It shows

Fig. 1

schematically the structure of an exemplary vacuum cleaner filter bag;

Fig. 2

a cross-section through an exemplary vacuum cleaner filter bag; and

Fig. 3

schematically a section of the through-flow surface of the bag wall of an exemplary vacuum cleaner filter bag.

For the determination of the parameters described above and below, the following methods are used.

The air permeability is determined according to DIN EN IS09237: 1995-12. In particular, a differential pressure of 200 Pa and a test area of 20 cm ^{2 are used} . For the Determination of air permeability, the air permeability tester FX3300 Texttest AG was used.

The basis weight is determined according to DIN EN 29073-1: 1992-08. For the determination of the thickness of the nonwoven layer, the method according to standard DIN EN ISO 9073-2: 1997-02 is used, using method A.

The determination of the maximum tensile force is carried out in accordance with DIN EN29073-3: 1992-08. In particular, a strip width of 50 mm is used.

Penetration (NaCl permeability) is determined using a TSI 8130 tester. In particular, 0.3 μm sodium chloride is used at 86 L / min.

The measurement of the number density of the welding points is carried out as follows. First, five mutually non-overlapping faces of the bag wall are selected, each of the faces is 10 cm ^{2 in} size and is completely enclosed by flow-through surface of the bag wall. In other words, none of the partial area directly adjoins the holding plate, the inflow opening and / or possibly existing weld seams. Each of the faces is surrounded by a square with a side of 3.16 cm. All partial surfaces may be arranged on the front side or the rear side of the filter bag, or one or more partial surfaces on the front side and one or more partial surfaces on the rear side.

In each of the partial surfaces, the welding spots arranged on the partial surface are then counted, and the ratio of the number of welding points to the total surface of the partial surface is formed for each of the partial surfaces. In other words, for each of the patches, the number of welds is divided by 10 cm ² . A welding point is arranged on the subarea when at least part of the surface of the welding point lies within the square surrounding the subarea.

Of the five values thus obtained, the arithmetic mean is then formed, i. the five values are added and then divided by five. The value thus obtained corresponds to the number density of the weld spots of the nonwoven fabric layer.

The determination of the pressing surface portion of the welding points is carried out as follows. First, five non-overlapping partial surfaces of the bag wall are selected, wherein each of the faces is 10 cm ^{2 in} size and is completely enclosed by the flow-through surface of the bag wall. In other words, none of the partial area directly adjoins the holding plate, the inflow opening and / or possibly existing weld seams. Each of the faces is surrounded by a square with a side of 3.16 cm. All partial surfaces may be arranged on the front side or the rear side of the filter bag, or one or more partial surfaces on the front side and one or more partial surfaces on the rear side.

In each of the sub-areas, the total area of the welding spots, that is to say the sum of the welding spot areas arranged on the sub-area, is then determined. The total area of the spot welds is determined by means of a measuring microscope and / or by means of image analysis. For each of the partial surfaces, the ratio of the total area of the welding spots to the total area of the partial area is then formed. In other words, for each of the patches, the total area of the welds is divided by 10 cm ² . Of the five values thus obtained, the arithmetic mean is then formed, ie the five values are added and then divided by five. The value thus obtained corresponds to the pressing surface portion of the welding points of the nonwoven fabric layer.

Fig. 1 shows the schematic structure of an exemplary vacuum cleaner filter bag 101. The filter bag 101 comprises an inflow opening 102 through which the air to be filtered flows into the filter bag 101. The exemplary filter bag 101 also includes a holding plate 103, which serves to fix the vacuum cleaner filter bag 101 in a chamber of a vacuum cleaner. The holding plate 103 is made of a plastic.

Also shows Fig. 1 the bag wall 104, wherein the bag wall 104 comprises exactly one nonwoven fabric layer in the form of a melt spun microfiber nonwoven layer. The exemplary filter bag 101 is formed as a flat bag.

The filter bag 101 is a single-layer, consisting of a nonwoven fabric layer of melt-spun microfiber spunbonded nonwoven fabric ("meltblown" nonwoven fabric), which was solidified pointwise by means of thermal calendering.

The nonwoven fabric layer of the exemplary filter bag 101 is made of PLA (polylactide). PLA can be purchased from Galactic Laboratories (Belgium), Cargill Dow Polymers LLC, Toyobo (Japan), Dai-Nippon, etc.

The basis weight or basis weight of the exemplary filter bag 101 is 85 g / m ² .

The embossed pattern of the bag wall 104 has a density of 25 spots per cm ² . The pressing surface portion of the embossing pattern is 17%.

With regard to the geometry or pattern of the welded joints, i. the distribution of welded joints on the permeable surface of the bag wall 104, the present invention is not subject to any restrictions. The pattern may be, for example, a pattern arranged at an angle of 45 ° to the machine direction.

It has been shown by experiments of the Applicant that a meltblown microfiber spunbonded nonwoven produced in this way achieves sufficient strength with satisfactory separation efficiency and air permeability.

In some markets there is a need for disposable vacuum cleaner bags, which are replaced after a short period of use, say after a few days. In particular, at high humidity and high temperature storage of the bag should be avoided with the sucked dust as possible, since an unavoidable in these conditions propagation of mold and bacteria in the filter bag can otherwise pose a hygienic problem. Filter bags made of multilayer nonwovens are usually too expensive for such short-term applications.

A single-layer filter bag, such as those associated with FIG. 1 described exemplary filter bag 101, can be produced or sold more cheaply and therefore is better suited for such a short service life.

FIG. 2 shows a cross section of an exemplary filter bag 201. The filter bag 201 includes a front 205 and a back 206, which are interconnected by a circumferential weld 207. In the front side 205 of the filter bag 201, an inflow opening 202 is provided, through which the sucked air can flow into the filter bag 201. A holding plate 203, which serves to fix the vacuum cleaner filter bag 201 in a chamber of a vacuum cleaner, is arranged in the region of the inflow opening 202 and connected to the bag wall of the filter bag 201.

A cutout 308 of the bag wall of an exemplary filter bag is shown in FIG Fig. 3 shown. The exemplary cutout 308 of the bag wall has a plurality of welds or welds 309 which have been formed by calender thermal consolidation on an embossing calender. Weld points 309 correspond to melt zone areas.

The embossing pattern has a density of 25 spots per cm ² . The pressing surface portion of the embossing pattern is 17%. In this example, the spot welds are distributed uniformly, ie at equal intervals, over the exemplary cutout 308 of the bag wall.

In particular, the weld spots can be distributed over the entire surface of the bag wall through the entire surface. Full surface does not mean in this context that all the fibers are completely connected to each other, for example, fused, resulting in a film. Rather, it means that the nonwoven layer is welded at a plurality of discrete locations, these locations being evenly distributed over the entire area of the nonwoven layer. The locations may be predetermined, for example in the case of a dot or gravure calender.

In the following table, exemplary properties of nonwoven fabrics are compared, wherein the nonwoven fabrics 1 and 2 correspond to the state of the art and nonwoven fabrics 3 and 4 are nonwovens according to the invention. Nonwoven fabric 1 Nonwoven fabric 2 Nonwoven fabric 3 Nonwoven fabric 4 Pressing area [%] none none 20 17 Welding points [points / cm ² ] none none 25 30 Areal mass [g / m ² ] 85 100 86 89 Thickness [mm] 1.2 0.99 0.65 0.62 Air permeability [l / (m ² s)] 210 213 130 134 Maximum tensile force in the machine direction [N] 31 31 101 98 Maximum tensile force transverse to machine direction [N] 19 10 86 60 Penetration (TSI 8130, 0.3 μm, 86 l / min) [%] 5.5 (corona charged) 48 (uncharged) 44 (uncharged) 46 (uncharged) 16 (corona charged)

All nonwovens shown in the table are made of polypropylene and are meltblown nonwovens, ie spun-bonded microfiber nonwovens. The exemplary nonwoven fabric 3 was in particular biaxially stretched.

It is understood that in the embodiments described above mentioned features are not limited to these specific combinations and also possible in any other combinations. Furthermore, it is understood that in the figures, neither the vacuum cleaner filter bag shown in a realistic dimensioning nor the welds shown are reproduced in a realistic distribution and number density.

Claims (9)

1. Vacuum cleaner filter bag (101; 201) with a bag wall (104), wherein the bag wall (104; 204) comprises precisely one nonwoven layer in the form of a meltblown nonwoven layer,
   wherein the nonwoven layer comprises a maximal tensile strength in the machine direction of more than 40 N, in particular of more than 60 N;
   wherein the nonwoven is a calendered nonwoven;
   wherein the press area proportion of the calendered nonwoven is 3 % to 50 %, in particular 10 % to 30 %;
   wherein the nonwoven layer comprises a number density of weld points (309) from 5/cm² to 50/cm², in particular 15/cm² to 40/cm²;
   wherein the nonwoven layer has a grammage of 30 g/m² to 200 g/m², in particular 40 g/m² to 150 g/m², in particular 120 g/m²; and
   wherein the bag wall (104) consists of the nonwoven layer in the form of a meltblown nonwoven layer, or
   wherein the bag wall comprises precisely one filter active layer in the form of the nonwoven layer and a netting.
2. Vacuum cleaner filter bag (101; 201) according to claim 1, wherein the nonwoven is a nonwoven calendered thermally or by means of ultrasound.
3. Vacuum cleaner filter bag (101; 201) according to one of the preceding claims, wherein the nonwoven layer comprises a maximal tensile strength in the transverse direction of more than 30 N, in particular more than 50 N.
4. Vacuum cleaner filter bag (101; 201) according to one of the preceding claims, wherein the thickness of the nonwoven layer is between 0.2 mm and 1.0 mm, in particular between 0.4 mm and 0.8 mm.
5. Vacuum cleaner filter bag (101; 201) according to one of the preceding claims, wherein the nonwoven layer comprises an air permeability of 40 l/(m²s) to 500 l/(m²s), in particular of 50 l/(m²s) to 300 l/(m²s), in particular of 80 l/(m²s) to 200 l/(m²s).
6. Vacuum cleaner filter bag (101; 201) according to one of the preceding claims, wherein the penetration of the nonwoven layer is smaller than 60 %, in particular smaller than 50 %, in particular smaller than 15 %.
7. Vacuum cleaner filter bag (101; 201) according to one of the preceding claims, wherein the nonwoven comprises a polymer, in particular polypropylene, or a biodegradable plastic, in particular PLA (polylactide).
8. Vacuum cleaner filter bag (101; 201) according to one of the preceding claims, wherein the nonwoven layer is electrostatically charged.
9. Vacuum cleaner filter bag (101; 201) according to one of the preceding claims, wherein the vacuum cleaner filter bag (101; 201) is a flat bag.

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