DE202005018003U1 - Dust filtration bag, e.g. for vacuum cleaner, includes a very open upstream layer only loosely attached to fine filtration downstream layers - Google Patents

Abstract

The upstream layer is attached to the subsequent filtration layers over no more than 7 % of the total surface or is attached only round the edges. It has a surface weight of less than 30 g/m2>, preferably 10 to 25 g/m2> and a dust separation according to DIN 44956-2 of less than 50 %. The upstream layer can be a spunbonded, thermally bonded or wet-laid non-woven containing a high proportion of synthetic fibers. The thickness of the upstream layer is 0.05 to 0.25 mm. The remaining fine filtration layers of the dust filtration bag can be made up of various three-layer combinations of spunbonded or meltblown non-wovens or paper joined by ultrasonic welding or by adhesives. Each layer has a weight in the region of 20 to 60 g/m2>.

Description

Territory of invention

The Invention relates to a dust filter bag with excellent filtration properties, in particular allow an excellent separation of fine and coarse dust and have an excellent service life.

State of technology

The Requirements related to the filtration properties of dust filter bags are made, are manifold and partly in opposite directions. Of great Significance is a high degree of separation for dusts with different types Particle sizes. Just the separation of fine and ultrafine dust is in view of the to aim for an increasing number of allergy sufferers. For the ease of use of greater Importance is about it In addition, the life of the dust filter bag. This means that a high suction power with as possible low clogging tendency of the filter over a long period of time is maintained. The bag filling is thus increased and the Bag rarely needs to be changed. This increases the acceptance of the product, because the change of the dust bag is usually the user felt as unhygienic.

in the Numerous types of dust filter bags are known in the prior art. In addition to classic filter bags made of paper or paper tissue are also from combinations of paper and nonwovens or fully synthetic Dust filter bag known. A three-layer spunbond-meltblown-spunbond composite (SMS) is described for example in EP-A-0 161 790. One Dust filter bag with SMS structure is also occasionally below as conventional Dust filter bag called. Leave with such filter materials achieve satisfactory separation rates for fine and coarse dust. However, bags of this design usually have an unsatisfactory Service life and service life.

Around To achieve long service life, WO 95/17946 proposes a coarse filter layer before, which has a very high degree of separation and a high porosity. According to the information in this patent application, this results in a Improvement of depth filtration. EP-A-1 254 693 is used to increase the lifetime of a prefilter layer, the NaCl degree of separation of at least 60%. EP-A-0 960 645 provides a coarse filter layer in front of which the bulk of the incident dust. This property is described in EP-A-960 645 by a Staubabscheidegrades according to DIN 44956-2 of at least about 66 to 67% (for wet-laid so-called High-capacity paper) quantified.

The measures described of the prior art to increase The service life is common that a voluminous prefilter layer tends to greater Thickness and depth filtration effect and thus high dust storage capacity used comes. A big Thick and a voluminous Construction brings with it bag manufacturing problems. For example makes the welding thick materials often difficult. About that In addition, due to the voluminous structure disadvantages in transport, Storage and packaging of the dust filter bag. These factors increase the Costs.

The WO 2005/060807 follows a different approach to increase the Service life of conventional dust filter bags with SMS structure. Here, fluidizable material is placed in the dust filter bag. In question, according to the information in this patent application fibers and Flakes, e.g. Chemical and natural fibers. The additional filling of the dust filter bag with Fluidizable material requires another process step with additional Costs and carries as well for the big one Volume of the dust bag, as the previously discussed coarse filter layer. this leads to to the already mentioned Disadvantages.

In front In this background, the problem to be solved according to the invention consists of dust filter bags with excellent separation efficiency, both for fine and coarse dust, as also excellent service life, which also cost more manufacture, packaging, storage and transport are to provide.

Summary the invention

The object is achieved by a dust filter bag, which comprises at least one inflow layer and a filtration layer, which is arranged on the downstream side of the inflow layer and consists of an at least three-layer composite, and which is characterized in that the at least one inflow layer in the dust filter bag over a maximum of 7 % of their area with the filtration layer ver has a basis weight (ISO 536) of <30 g / m ² and a total NaCl separation efficiency of <50%.

advantageous Further developments of the dust filter bag according to the invention are Subject of the dependent claims.

As already discussed, comes according to the teaching EP-A-1 254 693 discloses a pre-filter layer, for example a dry-laid layer and electrostatically active nonwoven fabric. The prefilter layer has a NaCl separation efficiency of at least 60% and is known as relatively voluminous called electrostatically charged filter layer. The prefilter layer preferably consists of staple fiber nonwoven fabric.

Surprisingly was now contrary to the teaching of EP-A-1 254 693 found that also with a low degree of separation of the upstream, over a maximum of 7% of their area with the filtration layer arranged layer compared to conventional Filter materials without this layer while maintaining a excellent separation efficiency for fine and coarse dust achieve a significant improvement in service life. It was for the expert completely unexpectedly that deals with an onflow layer as in claim 1 specified due to the low basis weight and the low separation efficiency no appreciable filtration effect or dust storage capacity has to achieve these technical effects. Furthermore offer the dust filter bag according to the invention due to their relatively small material thickness the mentioned advantages with regard to packaging, storage and transport.

It It should be noted that by the dust filter bag according to the invention over the usual Filter bags, for example based on SMS composite materials, a significant improvement in service life while maintaining the excellent Staubabscheidegrades is achieved.

Short description the drawings

The Figure shows a graph in which the suction power in dependence the applied amount of dust of a composite according to the invention across from Such is shown in the prior art.

Full Description of the invention

• • Flächengewicht: ISO 536,
• • Staubabscheidegrad: DIN 44956-2,
• • NaCl-Abscheidegrad: DIN EN 1822,
• • Luftdurchlässigkeit: EN ISO 9237, und
• • Dicke: ISO 534 (20 kPa).

Unless otherwise indicated, the following methods were used to determine the relevant parameters in the present application:

• Basis weight: ISO 536,
• Dust removal efficiency: DIN 44956-2,
• • NaCl separation efficiency: DIN EN 1822,
• • Air permeability: EN ISO 9237, and
• • Thickness: ISO 534 (20 kPa).

According to the invention, the inflow layer (en) for the improvement of the service life compared to conventional filter arrangements crucial layer (s). When using the dust filter bag according to the invention the dust-laden air hits the inflow layer first or inflow layers and then on to the filtration layer. According to the invention are Anströmschicht to understand the layer or layers that the filtration layer are upstream. Further layers on the downstream side of the Filtration layer are possible as long as the object of the invention An excellent separation efficiency for fine and coarse dust and a excellent service life is not impaired.

According to the invention, the weight per unit area of the individual inflow layers is <30 g / m ^{2 in} each case and the NaCl degree of separation in total, ie the sum of the degree of separation of all inflow layers <50%.

According to one preferred embodiment the dust filter bag has only one inflow layer.

The feature that the at least one inflow layer in the dust filter bag is connected to the filtration layer over a maximum of 7% of its area includes the case where the inflow layer is not in any connection with the filtration layer, except at the side seam and / or at the dust inlet opening, for example the retaining plate has. In this case, the inflow layer is loose in the dust filter bag. This embodiment of the invention is preferred. In the manufacture of the dust filter bag by superimposing the corresponding layers and connection of the layers along the circumference may further inventin The inflowing layer (s) and the filtration layer in the edge area of the bag are connected to one another. There are also such embodiments of dust filter bags included in the scope of the invention, in which, apart from the side seam, there is also a connection over the actual filtration surface, provided that the maximum bonding area of 7% is not exceeded. Preferably, said bonding surface of the inflow layer (s) and the filtration layer is at most 5%, more preferably at most 3%, even more preferably at most 2%, and most preferably at most 1%. If there are several inflow layers in the dust filter bag, they can be connected to one another as desired, that is to say also over the entire surface, as long as the connection with the filtration layer is specified as in claim 1.

in the dust filter bag according to the invention covers the inflow layer preferably at least 40%, more preferably at least 70% and most preferably 100% of the outflow downstream filtration layer from.

The Production of dust filter bags from the layers is the expert well known. Depending on the bag design come different techniques for use. For example, the bag by tubing be generated from a web of the filter medium and closing the longitudinal seam. After this Shorten of the hose, the hose ends are closed. This can done either by two so-called winding floors or by a so-called block floor and a changing bottom. For thermoplastic Materials can the hose ends are also closed by welding.

As is known the dust inlet opening of the bag before the tube is formed, then on the holding plate is applied.

at another method - preferred in fully synthetic filter media that can be welded, two webs of the Filter medium or layer combinations superimposed lying together and the bag afterwards generated by a circumferential seam. The inlet opening is here in a Train before the merge the two lanes generated and often Immediately thereafter, the holding plate is applied, d. H. before the actual Bag production.

Of the Composite of the webs can be used both by gluing techniques as well thermoplastic filter media by welding - thermally or by ultrasound - done.

The at least one inflow layer has a NaCl separation efficiency in total (i.e., a degree of separation of all inflow layers) of preferably <40%, more preferably <30% and most preferably <20%. The dust removal efficiency is preferably <30% and most preferably <20%. According to one particularly preferred embodiment has the at least one inflow layer a NaCl separation efficiency and a degree of dust separation of <20% (in total).

Of the A person skilled in the art is able, within the scope of his specialist knowledge, to use inflow layers with a suitable degree of separation (for both NaCl and dust). there he uses the following basic connections, the known to him from his expertise. The degree of separation depends on the fiber strength from. The thinner a fiber is the higher is the degree of separation of the corresponding layer. Another influencing factor is the electrostatic charge. The higher the charge of the filter medium is, the higher its degree of separation, especially for Fine particles. Further leaves the degree of separation through the use of triboelectric fibers, as described in EP-A-1 254 693, further increase. Also the Thickness of the medium influences the degree of separation. This is the degree of separation the higher, the thicker the material is. The porosity of the medium also influences the Separation. The lower the porosity of a medium, i. more the denser it is, the higher is its degree of separation. Also affect the pore size or the free pore volume the degree of separation: the smaller the pores, the higher the degree of separation of the medium.

When Materials of the at least one inflow layer are spun nonwovens and Thermovliese preferred for use. Furthermore, with the Spunmeltverfahren produced materials are used. In addition, come drained Staple fiber webs, as well as wet-laid media, in particular nonwovens in question, which has a share of synthetic fibers of at least 20% included or complete made of synthetic fibers. The production process of such sheet are described in the literature, e.g. in "Nonwovens", edited by W. Albrecht, H. Fuchs and W. Kittelman, Wiley-VCH Verlag, Weinheim 2000.

The air permeability of the at least one inflow layer is preferably 1,500 to 10,000, more preferably 3,000 to 8,000, and still more preferably 4,000 to 6,000 l / m ² s. Their porosity is preferably> 95%, particularly preferably> 98%. Their thickness is preferably 0.05 to 0.25 mm, more preferably 0.1 to 0.2 mm. The basis weight is preferably in each case 10 to 25 g / m ² , more preferably 10 to 20 g / m ² and very particularly preferably 12 to 16 g / m ² .

The Filtrationsschicht qualifies as such due to their Staubabscheidegrades (according to DIN 44956-2) of at least 80%, preferably at least 85%, more preferably at least 90%, more preferably at least 95% and in particular 99% and above.

Of the Three-layer composite of the filtration layer is in terms of materials The individual layers are not particularly limited, as long as they have one Dust removal efficiency according to DIN 44956-2 having.

• Spinnvlies → Meltblown → Spinnvlies
• Thermovlies → Meltblown → Spinnvlies
• Naßgelegtes Vlies → Meltblown → Spinnvlies
• Spinnvlies → Spinnvlies → Meltblown → Spinnvlies
• Spinnvlies → Thermovlies → Meltblown → Spinnvlies
• Spinnvlies → naßgelegtes Vlies → Meltblown → Spinnvlies.
• Spinnvlies → Meltblown → Papier
• Spinnvlies → Meltblown → naßgelegtes Vlies
• Thermovlies → Meltblown → Thermovlies

As examples of combinations of the filtration layer are mentioned (sequence always seen from upstream side):

• Spunbond → meltblown → spunbonded web
• Thermal Fleece → Meltblown → Spunbonded Nonwoven
• Wet-laid fleece → meltblown → spunbonded fabric
• Spunbonded fabric → spunbonded fabric → meltblown → spunbonded fabric
• Spunbonded nonwoven → Thermal nonwoven → Meltblown → Spunbonded nonwoven
• Spunbonded fabric → wet laid fabric → meltblown → spunbonded fabric.
• Spunbond → meltblown → paper
• Spunbond → meltblown → wetlaid nonwoven
• Thermal Fleece → Meltblown → Thermal Fleece

This are just examples and a lot of other combinations possible and known to those skilled in the art.

• Spinnvlies-Meltblown-Spinnvlies
• Spinnvlies-Meltblown/Spinnvlies
• Thermovlies-Meltblown-Spinnvlies
• Thermovlies-Meltblown/Spinnvlies
• Naßgelegtes Vlies-Meltblown-Spinnvlies
• Spinnvlies-Spinnvlies-Meltblown-Spinnvlies
• Spinnvlies-Thermovlies-Meltblown/Spinnvlies
• Spinnvlies-naßgelegtes Vlies-Meltblown-Spinnvlies
• Spinnvlies-Meltblown-Papier
• Spinnvlies-Meltblown/Papier
• Thermovlies-Meltblown/naßgelegtes Vlies
• Thermovlies-Meltblown-Thermovlies

Particularly preferably, the layers in the above-mentioned combinations of the filtration layer are connected as follows (the partial bonding of the individual layers over the entire surface by gluing / welding is in each case marked with a "-", a missing connection over the surface, ie at most one connection via the side seam and / or the dust inlet opening by "/"):

• Spunbond-meltblown-spunbond
• Spunbond-meltblown / spunbond
• Thermovlies meltblown spunbond
• Thermovlies meltblown / spunbond
• Wet laid nonwoven meltblown spunbonded web
• Spunbond-spunbond-meltblown-spunbond
• Spunbond nonwoven thermal meltblown / spunbond
• Spunbond wet laid nonwoven meltblown spunbonded web
• Spunbond-meltblown-paper
• Spunbond-meltblown / Paper
• Thermal Fleece Meltblown / Wetlaid Fleece
• Thermovlies meltblown Thermovlies

Especially preferred is the three-layer composite of the filtration layer, a Spunbond meltblown nonwoven spunbond (SMS) composite. It is preferred that the spunbonded layer of the SMS composite, that of the Anströmschicht is facing, at least partially over the entire surface with the subsequent Meltblownlage is connected. Very particularly preferred are all Single layers of the SMS network via their entire area, at least partially interconnected. It is under the partial Connecting the layers together to understand a compound at from 0.1 to 30%, preferably from 0.2 to 10%, more preferably from 0.3 to 2% of the relevant layer areas connected to each other.

The meltblown web, which according to the invention preferably represents at least one layer of the composite of the filtration layer, advantageously has a basis weight of 10 to 120 g / m ² , more preferably in the range of 25 to 50 g / m ² , in particular in the range of 30 to 45 g / m ² . In order to achieve good dust separation, in particular for fine dust, it is favorable if the meltblown layer has a thickness of 0.10 to 4 mm, preferably 0.18 to 3 mm. In order to ensure a high suction capacity of the vacuum cleaner, the meltblown layer preferably has an air permeability of 100 to 2,000 l / m ² s, more preferably 200 to 1,500 l / m ² s, particularly preferably from 250 to 600 l / m ² s , The pore diameter of the meltblown layer is preferably 15 to 60 .mu.m, particularly preferably 25 to 40 .mu.m, and the average fiber diameter is preferably between 0.5 and 18 .mu.m, more preferably between 1 and 3 .mu.m. For reasons of stability, the fracture resistance of the meltblown layer is preferably in the longitudinal direction 2 to 12 N / 15 mm strip width and in the transverse direction 1 to 10 N / 15 mm strip width.

Of the Staubabscheidegrad (according to DIN 44956-2) of the meltblown layer is preferably in the range of 80% to nearly 100%.

The Meltblown layer is in a preferred embodiment with a permanent one provided electrostatic charge, for even better dust separation of fine particles. In addition to the purely mechanical filtration additional acts here an electrical filtration due to an electrostatic Attraction of filter material and oppositely charged dust particles. The fibers of the nonwoven preferably carry spatially separated bipolar charges. The electrostatic charge can be achieve by using the filter materials in nonwoven production exposed to an electric field. The procedures used are described in the literature, see e.g. Martin Davis, Electrostatic Melt Spinning Process Deliver's Unique Properties, Non-Woven's World, September 1987, pages 51-54, or Troulihet, Y .; Moosmayer, P .; New Method of Manufacturing Non-Woven by Electrostatic Laying, presented at Index 81 Congress.

The Meltblown layer can be melt blown (e.g., Exxon process) getting produced. The fiber material is melted, extruded, when the filaments exit the spinneret, they are drawn with hot air, swirled, placed on a sieve (sieve or cylinder design) and of this finally as sheet decreased. As a result of the manufacturing process, there is the meltblown layer typically made of long, fine fibers common for meltblowns average fiber diameter of 0.5 to 18 microns.

Further Details of usable meltblown layers can be found in EP-A-0 338 479.

in the The following examples are given which illustrate the invention, however should not restrict.

Examples

Filter materials were tested, which consist of certain spunbonded nonwovens (hereinafter referred to as SB) and meltblown nonwovens (hereinafter referred to as MB). The key figures of the corresponding layers are summarized in the following table:

The porosity was calculated according to the following formula: 100 - (volume of fibers x 100 / volume of nonwoven) =%

Where: Volume fleece = (area × thickness); Volume of fibers = weight of nonwoven of equal area / density of polymer

The suction power of a Siemens vacuum cleaner (DINO XS 1800W) was determined at different bag filling levels. The dust used was DMT 8 test dust. The suction power (in l / s) was determined on the suction tube by means of a rotameter. 1 shows the results. In the name of the layer orders in 1 symbolizes a hyphen between adjacent layers a bond by means of point-shaped ultrasonic welding, wherein the pressing surface was about 1% of the total filtration area. A slash between two adjacent layers indicates that the layers are not connected to one another via the filtration surface but only at the side seam and in the region of the dust inlet opening. The calculated percentage area of contact and filtration layer of the tested dust filter bags at the side seam and at the dust inlet was in the range of 2.5 to 2.7%. All spunbonded nonwovens with a basis weight below 30 g / m ² have a degree of separation (both for NaCl as well as for dust) of well below 50%.

As it turned out 1 results from the version SB30 / [SB14-MB30-SB25], which is used as a comparative example in EP-A-1 254 693 (a spunbonded web having a weight per unit area of 30 g / m ^{2 is} used as the inflow layer) Improvement of service life, as can be seen from the significantly larger suction power as a function of the test dust filling of the dust filter bag. In addition, the separation efficiency of the dust filter bag remains at a comparable outstanding level when the basis weight of the inflow layer is reduced. This was determined using a device for determining the fractional separation efficiency of Palas.

It was completely surprising for the expert that when using a dust filter bag according to the invention, for example, the in 1 SB14 / [SB14-MB30-SB25] dust filter bag gives a significant improvement in service life, although the spunbonded web has a basis weight of only 14 gsm and a thickness of only 0.13 mm. Because of these product properties, the inflow layer has a very low dust storage capacity, which would be expected for the skilled person that the life of the overall composite is not significantly improved.

Claims (16)

Dust filter bag, comprising: (i) at least one inflow layer and (ii) a filtration layer which is arranged on the outflow side of the inflow layer and consists of an at least three-ply composite, characterized in that the at least one inflow layer in the dust filter bag over a maximum of 7 its surface with the Filtration layer is connected, and a basis weight (ISO 536) of <30 g / m2 and a NaCl separation efficiency of a total of <50 has. Dust filter bag according to claim 1, in which the basis weight of the at least one inflow layer is 10 to 25 g / m ² each. Dust filter bag according to claim 1 or 2, in which the at least one inflow layer has a Staubabscheidegrad (DIN 44956-2) of total <50%. Dust filter bag according to at least one of claims 1 to 3, in which the at least one inflow layer with the filtration layer only at the side seam and in the area of the dust inlet opening of the Bag is connected. Dust filter bag according to at least one of claims 1 to 4, in which the at least one inflow layer consists of a spunbonded nonwoven, Thermo-nonwoven or a wet-laid high-synthetic or wet-laid fully synthetic Fleece or combinations thereof. Dust filter bag according to at least one of claims 1 to 5, in which at least one layer of the composite of the filtration layer is a meltblown fleece. Dust filter bag according to claim 6, in which the meltblown web a basis weight from 10 to 120 g / m2. Dust filter bag according to at least one of claims 1 to 7, in which the three-layer composite of the filtration layer is a spunbond meltblown nonwoven spunbond composite is. Dust filter bag according to claim 8, wherein the spunbonded nonwoven fabric of the spunbond-meltblown non-woven spunbond composite each independently a basis weight from 20 to 60 g / m2. Dust filter bag according to at least one of claims 6 to 9, in which in the composite of the filtration layer at least the meltblown nonwoven upstream layer with the meltblown nonwoven over its entire surface at least is partially connected. Dust filter bag according to at least one of claims 1 to 5, in which at least one layer of the composite of the filtration layer a membrane for the air filtration is. Dust filter bag according to at least one of claims 1 to 11, in which the individual layers of the composite of the filtration layer by ultrasonic welding connected to each other. Dust filter bag according to at least one of claims 1 to 11, in the individual layers of the composite of the filtration layer connected by gluing together. Dust filter bag according to at least one of claims 1 to 13, in which the air permeability (EN ISO 9237) of the at least one inflow layer is in each case 1500 to 10,000 l / m ² s. Dust filter bag according to at least one of claims 1 to 14, in which the thickness (ISO 534) of the at least one inflow layer each 0.05 to 0.25 mm. Dust filter bag according to at least one of claims 1 to 15, wherein the at least one inflow layer is a spunbonded nonwoven, the filtration layer is a spunbond meltblown nonwoven spunbond composite, and the spunbond and spunbond meltblown nonwoven spunbond composite are immediately adjacent in the dust filter bag.