AU2019259443B2

AU2019259443B2 - Vacuum cleaner filter bag with film in the region of the holding plate

Info

Publication number: AU2019259443B2
Application number: AU2019259443A
Authority: AU
Inventors: Ralf Sauer; Jan Schultink
Original assignee: Eurofilters Holding NV
Current assignee: Eurofilters Holding NV
Priority date: 2018-04-27
Filing date: 2019-03-21
Publication date: 2021-09-30
Anticipated expiration: 2039-03-21
Also published as: CN112105280B; CN112105280A; ES2937794T3; EP3560402B1; EP3560402A1; AU2019259443A1; DK3560402T3; PL3560402T3; WO2019206532A1; RU2753555C1

Abstract

The invention relates to a vacuum cleaner filter bag comprising a bag wall and a holding plate which is connected to the bag wall. The bag wall has a film region in which a plastic film is arranged, and the film region comprises a first sub-region in which the bag wall is formed solely by the plastic film or in which the plastic film forms the outermost layer of the bag wall. The film region comprises a second sub-region in which the plastic film is overlapped by a nonwoven fabric element (3). The holding plate is connected to the plastic film and the nonwoven fabric element (3), in particular the holding plate is welded thereto, and the nonwoven fabric element (3) has at least one part (11, 12) which is connected to the bag wall part surrounding the film region.

Description

Vacuum cleaner filter bag with film in the region of the retaining plate

Background

[0001] The invention relates to a vacuum cleaner filter bag comprising a bag wall and a retaining plate which is connected to the bag wall, the bag wall comprising a film region in which a plastic film is arranged.

[0002] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

[0003] Vacuum cleaner filter bags of this kind are known, for example, from EP 3 066 968. Often, the plastic film is a transparent film. The film region is therefore transparent and makes it possible to visually determine how full the vacuum cleaner filter bag is. It is also known to arrange viewing win dows in the form of transparent films in other regions of the bag wall, for example from DE 20 2005 007 503 and DE 102 24 561. However, in many vacuum cleaner models, viewing windows in the region of the retaining plate have the advantage that they are particularly easy to see through.

[0004] Aside from forming transparent regions, films are also used, for example, to prevent the build-up of a filter cake or to reduce the abrasion of the filter material in particularly stressed regions inside the bag. Films in the region of the bag wall are also known from EP 2 025 278 and DE 20 2008 004025.

[0005] EP 3 066 968 also describes non-transparent films in the region of the retaining plate for fa cilitating the insertion of the retaining plate into the corresponding receptacle in the vacuum cleaner housing. The plastic film therefore forms the outermost layer of the bag wall in this region.

[0006] In the latter case and in the case of a transparent film in the region of the retaining plate for forming a viewing window, the retaining plate is connected to the plastic film.

[0007] However, it has proven problematic to weld a retaining plate to a film. The highest achieva ble tensile force is usually insufficient, and therefore the retaining plate too easily becomes detached from the bag wall, in particular the film. Holes or weak points that tear further under loading often ap pear in the film on account of the joint welding.

[0008] In order to improve the connection between the retaining plate and the film, it is known from WO 2017/098035 to arrange a textile material between the retaining plate and the film. How ever, this solution has the disadvantage that several elements have to be mutually aligned.

[0009] An object of the present invention is therefore to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. It is also an object of at least one embodiment of the invention to provide a vacuum cleaner filter bag which is more efficient to produce and a method which makes possible this more efficient production of a vacuum cleaner filter bag.

Summary

[0010] According to an aspect of the invention there is provided a vacuum cleaner filter bag com prising a bag wall and a retaining plate which is connected to the bag wall, wherein the bag wall com prises a film region in which a plastic film is arranged, wherein the film region comprises a first sub-region in which the bag wall is formed solely by the plastic film or in which the plastic film forms the outermost layer of the bag wall, wherein the film region comprises a second sub-region in which the plastic film is overlapped by a nonwoven fabric element, wherein the retaining plate is connected, in particular welded, to the plastic film and the nonwoven fabric element, wherein the nonwoven fabric element has at least one part which is connected to the bag wall part surrounding the film region; wherein the nonwoven fabric element comprises a through-hole which is arranged concentri cally with respect to a through-hole in the plastic film and a through-hole in the retaining plate; and wherein the nonwoven fabric element comprises an annular region that surrounds the through-hole and that is connected to the bag wall part surrounding the film region via at least one connection piece, and wherein the retaining plate is connected to the nonwoven fabric element in the annular region.

[0011] According to another aspect of the invention there is provided a method for producing a vacuum cleaner filter bag, comprising the steps of punching at least one through-opening into a sheet of nonwoven fabric such that a region free of nonwoven fabric is formed in the sheet of nonwoven fabric and a nonwoven fabric element is left which is arranged between two opposing edge portions of the region free of nonwoven fabric and which is spaced apart from the opposing edge portions in each case by means of a sub-region of the region free of nonwoven fabric; connecting a plastic film to the sheet of nonwoven fabric such that, when the sheet of nonwo ven fabric is viewed in plan view, the plastic film completely overlaps with the region free of nonwoven fabric and the nonwoven fabric element; forming a through-hole in the plastic film and in the nonwoven fabric element; welding a retaining plate to the plastic film and the nonwoven fabric element.

[0012] According to the invention, the retaining plate is not only connected to the plastic film, but

also to a nonwoven fabric element that overlaps with the plastic film in part. The nonwoven fabric ele

ment has at least one part which is connected, in particular directly, to the part of the bag wall that

surrounds the film region. As a result, the positioning of the nonwoven fabric element in relation to the

plastic film and the retaining plate can be improved. In particular, it is not necessary to align the

nonwoven fabric element as a separate component relative to the film and the retaining plate. This en

ables an increased production efficiency of the vacuum cleaner filter bag.

[0013] In the context of the present invention, "region" refers to a three-dimensional part of an el

ement that is characterized by one or more specific properties. For example, the film region of the bag

wall is the three-dimensional bag wall part in which the plastic film is arranged.

[0014] The plastic film may be designed to be transparent or non-transparent. The plastic film may

in particular be referred to as transparent or see-through if the proportion of visible light that can pass

through the plastic film is at least 25%, in particular at least 50%. In particular, this proportion may pass

through the plastic film such that imaging of an object located behind it is possible. In other words, the

light passing through is not diffuse light.

[0015] In the case of a transparent plastic film, the first sub-region of the film region thus forms a

transparent region of the bag wall that makes it possible to look into the interior of the vacuum cleaner

filter bag. The transparent region therefore forms a sort of viewing window in the bag wall. In this case,

in particular, the bag wall in the first sub-region may be formed solely by the plastic film. If necessary, a

net or a further transparent element may be connected to the bag wall and overlap with the first sub

region, wherein, however the net or other transparent element is designed such that it does not pre

vent visual inspection of the interior of the vacuum cleaner filter bag through the transparent region.

[0016] The first sub-region of the film region does not have to be designed to be contiguous. For

example, the first sub-region may comprise at least two parts that are separated from one another by

the second sub-region of the film region.

[0017] In the context of the present invention, the bag wall part surrounding the film region refers

to the bag wall part that adjoins, in particular directly, the region in which the plastic film is arranged.

[0018] It may be possible to attach the retaining plate to a retaining means in a vacuum cleaner

housing. As a result, it may be possible to arrange, in particular to secure, the retaining plate in a pre

determined position in the vacuum cleaner housing. Alternatively, it may be possible to slide the vac

uum cleaner filter bag over a connection nozzle on the vacuum cleaner with the aid of the retaining

plate.

[0019] In particular in the case of a non-transparent plastic film, the bag wall may form the outer

most layer of the bag wall in the first sub-region. This makes it possible to facilitate insertion of the re

taining plate into the corresponding receptacle in the vacuum cleaner housing. A transparent plastic

film may also form the outermost layer of the bag wall. If said transparent plastic film does not overlap

with non-transparent parts of the bag wall, it can be used as a viewing window and for easier insertion

of the bag into the holder of the vacuum cleaner.

[0020] The plastic film may in particular be referred to as non-transparent or opaque if the propor

tion of visible light that can pass through the plastic film is less than 25%, in particular less than 10%.

The plastic film may also be referred to as non-transparent or opaque if the proportion of visible light

that can pass through the plastic film is greater than 25%, but this proportion passes through the plas

tic film such that imaging of an object behind it is not possible. In other words, the light passing

through is diffuse light in that case.

[0021] The nonwoven fabric element may in particular be manufactured from the same material as

the bag wall surrounding the film region. The nonwoven fabric element may in particular be integrally

formed with the bag wall surrounding the film region. In other words, according to a preferred embodi

ment of the invention, the nonwoven fabric element is not a separate element connected to the bag

wall surrounding the film region, but rather an integral part. This can be achieved by the bag wall part

surrounding the film region comprising one or more layers of nonwoven fabric and the nonwoven fab

ric element being formed as a residual part of said nonwoven fabric layers in one or between multiple

cut-outs.

[0022] The nonwoven fabric element may comprise a through-hole which is arranged concentri

cally with respect to a through-hole in the plastic film and a through-hole in the retaining plate. As a

result, an inflow opening through which the dust-laden air can enter the bag interior can be formed. In

particular, a nozzle of a vacuum cleaner can be introduced at least in part in the vacuum cleaner filter

bag via the through-hole in the retaining plate and the through-holes in the plastic film and nonwoven

fabric element.

[0023] The nonwoven fabric element may comprise an annular region that surrounds the through

hole and that is connected to the bag wall part surrounding the film region via at least one connection

piece, and wherein the retaining plate is connected to the nonwoven fabric element in the annular re

gion. The annular region may be dimensioned such that it is completely connected, in particular

welded, to the retaining plate. As a result, the annular region looks no different to the direct connec

tion of the retaining plate to the transparent plastic film, as is known, for example, from EP 3 066 968.

[0024] Compared to a direct connection to the film, in this example i the at least one connection

piece, by means of which the annular region is connected to the bag wall part surrounding the film re

gion, remains as a significant optical difference. However, the connection piece may have much smaller

dimensions than the first sub-region. In a plan view of the bag wall part in which the film region and

retaining plate are arranged, the surface area of the region of the connection piece that overlaps with

the plastic film is thus smaller than the surface area of the first sub-region.

[0025] Two or more connection pieces may also be provided in order to connect the annular region

to the bag wall part surrounding the film region, in particular two, three or four connection pieces. In

the case of two connection pieces, they may connect the annular region in particular to opposing sides

of the bag wall part surrounding the film region. This enables a particularly advantageous stabilisation

and localisation of the nonwoven fabric of the bag wall and of the nonwoven fabric element during

production. In the case of four connection pieces, the connection pieces may connect the annular re

gion to the bag wall part surrounding the film region in pairs on opposing sides of the film region.

[0026] It should be noted that, in the context of the present invention, the term "annular" is not

limited to the shape of a circular ring. The actual shape of the annular region may be adapted to the

shape of the region of the retaining plate provided for connection to the bag wall. As a general rule,

the annular region may be a closed region that surrounds the through-hole in the plastic film and

nonwoven fabric element. The annular region may extend between a closed inner and a closed outer boundary line. The boundary lines may be circular, elliptical or shaped in any other desired manner.

The boundary lines may cross the at least one connection piece. The splitting into an "annular region"

and "connection piece" merely serves to describe the geometry of the nonwoven fabric element. The

annular region and at least one connection piece are in fact integral components of the nonwoven fab

ric element described here and are merged.

[0027] The outer boundary of the film region may be rectangular or square. In other words, the

plastic film may be rectangular or square. However, the plastic film may also have other shapes, for ex

ample it may be round or oval. The outer boundary may be formed by a weld seam that connects the

plastic film to the nonwoven fabric of the bag wall. Said weld seam may simultaneously be part of or

correspond to the bag wall part surrounding or delimiting the film region.

[0028] Within the context of the present invention, "connection piece" should be understood to

mean an element that proceeds from one edge of the outer boundary and connects said edge to an

other element of the nonwoven fabric element, for example to the annular region. In its simplest form,

the connection piece is rectangular or square in a plan view of the bag wall part comprising the film re

gion. However, other geometries are also conceivable.

[0029] As mentioned above, two connection pieces may connect two opposing sides or edges of

the outer boundary to the annular region.

[0030] The retaining plate and the plastic film may be arranged such that the nonwoven fabric ele

ment is located between the retaining plate and the plastic film.

[0031] Alternatively, the retaining plate and the plastic film may be arranged such that the plastic

film is located between the retaining plate and the nonwoven fabric element.

[0032] The bag wall of the vacuum cleaner filter bag, in particular the bag wall part surrounding the

film region and also the nonwoven fabric element, may comprise one or more filter material layers, in

particular one or more nonwoven fabric layers. Vacuum cleaner filter bags comprising several filter ma

terial layers are known, for example, from EP 2 011556 and EP 0 960 645. A wide variety of plastics

may be used for the nonwoven fabric layers, for example polypropylene and/or polyester. The bag wall

of the vacuum cleaner filter bag may also comprise recycled plastic. For example, the bag wall may be

designed in the manner described in EP 3 219 376 Al.

[0033] The term nonwoven (German "Vliesstoff") is used according to the definition in ISO Stand

ard IS09092:1988 or CEM Standard EN29092. In particular, the terms fibrous web or web and

nonwoven fabric are defined in the field of the manufacture of nonwoven fabrics and also to be

understood in the context of the present invention as follows. For the manufacture of a nonwo

ven, fibers and/or filaments are used. The loose or loose and still unbound fibers and/or filaments are

referred to as web or fibrous web. Via a so-called web bonding step, a nonwoven fabric is finally

formed from such a fibrous web, which has sufficient strength to be, e.g., wound up into rolls. In other

words, a nonwoven fabric is made self-supporting by bonding. (Details of the use of the definitions

and/or processes described herein can also be found in the standard work "Nonwovens", W. Albrecht,

H. Fuchs, W. Kittelmann, Wiley-VCH, 2000).

[0034] The plastic film may be directly connected, in particular welded, to one or more nonwoven

fabric layers of the bag wall. In addition, the plastic film may be directly connected, in particular

welded, to the at least one connection piece of the nonwoven fabric element. As a result, the at least

one connection piece for connecting the retaining plate to the bag wall can be used, which further in

creases the stability of the connection between the retaining plate and the bag wall.

[0035] When reference is made herein to "welding", this should be understood to mean connec

tion by means of ultrasonic welding.

[0036] The plastic film may be a blown film or a cast film. The term "film" refers to an element of

which the thickness is substantially lower than the extent thereof (length and width) perpendicular to

the thickness. For example, a film may have an, in particular constant, thickness of less than 300 pm,

for example 100 pm. The plastic film may be manufactured from polypropylene, PP, polyethylene, PE,

polyethylene terephthalate, PET, polyamide, PA, or polycarbonate, PC.

[0037] In claim 6, the invention provides a method for producing a vacuum cleaner filter bag, in

particular a vacuum cleaner filter bag as described above. According to this method, at least one

through-opening is punched into a sheet of nonwoven fabric such that a region free of nonwoven fab

ric is formed in the sheet of nonwoven fabric. The region free of nonwoven fabric is formed such that,

after punching, a nonwoven fabric element is left which is arranged between two opposing edge por

tions of the region free of nonwoven fabric and which is spaced apart from the opposing edge portions

in each case by means of a sub-region of the region free of nonwoven fabric.

[0038] According to the prior art, a rectangular or square through-opening would have been

punched and a plastic film would have been arranged herein afterwards. In order to connect the re

taining plate to the film, a separate textile element would have to be produced and aligned relative to

the film together with the retaining plate. According to the invention, the nonwoven fabric element

remains part of the sheet of nonwoven fabric after the at least one through-opening is punched, which

greatly simplifies production and alignment.

[0039] If one through-opening is punched, the through-opening forms the region free of nonwoven

fabric. If more than one through-opening is punched, the region free of nonwoven fabric is formed by a

combination of the punched through-openings. The region free of nonwoven fabric may comprise a

plurality of non-contiguous sub-regions and/or a plurality of contiguous sub-regions. The sub-regions

may each be formed by one of the through-openings.

[0040] The nonwoven fabric element is arranged between two opposing edge portions. In other

words, there are two edge portions on the edge of the region free of nonwoven fabric which are oppo

site one another and between which the nonwoven fabric element is arranged. There also may be a

plurality of pairs of opposing edge portions on the edge of the region free of nonwoven fabric between

which the nonwoven fabric element is arranged.

[0041] The nonwoven fabric element may be arranged fully or partially between two opposing

edge portions. Further edge portions may also be arranged between the opposing edge portions.

[0042] The edge of the region free of nonwoven fabric is formed by a combination of the edges of

the through-openings. The edge of the region free of nonwoven fabric may therefore also comprise a

plurality of non-contiguous edge portions. For example, the region free of nonwoven fabric may be

formed by two separate, i.e. non-contiguous, through-openings. In this case, the edge of the region

free of nonwoven fabric is composed of the non-contiguous edges of both through-openings.

[0043] The formation of the through-hole in the plastic film may take place at the same time as the

formation of the through-hole in the nonwoven fabric element. However, it is also conceivable for the

through-hole to be formed in the nonwoven fabric element before the through-hole is formed in the

plastic film.

[0044] After the retaining plate is welded to the plastic film and nonwoven fabric element, the

sheet of nonwoven fabric may be cut to the appropriate size and the vacuum cleaner filter bag may be assembled. In particular, the vacuum cleaner filter bag may be produced as a flat bag. In this case, an upper layer may be circumferentially welded to a lower layer, the film region being arranged together with the retaining plate in the upper layer, for example.

[0045] In particular, two through-openings may be punched which are formed symmetrically with

respect to an axis of symmetry that extends in the machine direction, in particular wherein the

through-openings are punched such that the nonwoven fabric element remains between the through

openings.

[0046] It is also conceivable to punch more than two through-openings, for example three or four.

In this case, too, symmetry with respect to an axis of symmetry that extends in the machine direction is

advantageous and possible. The nonwoven fabric element may be arranged partially between two or

more than two through-openings in each case. The region of the sheet of nonwoven fabric in which the

region free of nonwoven fabric and the nonwoven fabric element are arranged may have a rectangu

lar, in particular square, boundary.

[0047] The nonwoven fabric element may comprise, before the through-hole is formed, a region in

the shape of a disc and at least one connection piece, which connects the region in the shape of a disc

to the rest of the sheet of nonwoven fabric.

[0048] The region in the shape of a disc forms a sort of extension of the nonwoven fabric element

that extends transversely to the machine direction. This is where the through-hole is to be formed and

the retaining plate to be attached later. The region in the shape of a disc may be punched so as to be

annular, the retaining plate being connected, in particular welded, to the annular region of the nonwo

ven fabric element.

[0049] A single connection piece is less stable than a plurality thereof. In particular, if the sheet of

nonwoven fabric is pulled, the at least one punched through-opening can be deformed and the sheet

of nonwoven fabric can warp and/or wave in the region of the through-opening. By means of at least

two connection pieces, the sheet of nonwoven fabric can be stabilized such that the undesired effects

do not occur or occur less. Accordingly, the sheet speed between cycles and thus the production speed

can be increased.

[0050] The connection pieces may in particular be arranged on sides of the region in the shape of a

disc that oppose one another in the machine direction. Additional connection pieces may also be ar

ranged on two sides of the region in the shape of a disc that oppose one another transversely to the

machine direction. It is also conceivable for one or more connection pieces to extend at an angle of 20

to 60°, in particular 45, relative to the machine direction.

[0051] The retaining plate may comprise guides which are arranged in a region of the retaining

plate surrounding a through-hole of the retaining plate, the radial extension of which region corre

sponds to that of the annular region of the nonwoven fabric element. In other words, the annular re

gion may be adapted to the region of the retaining plate in which the guides are arranged, and is there

fore provided for connecting the retaining plate to the nonwoven fabric element and plastic film.

[0052] The retaining plate and the plastic film may be arranged such that the nonwoven fabric ele

ment is located between the retaining plate and the plastic film after connection of the retaining plate.

[0053] Alternatively, the retaining plate and the plastic film may be arranged such that the plastic

film is located between the retaining plate and the nonwoven fabric element after connection of the

retaining plate.

[0054] These two alternatives can be achieved by welding the plastic film to the sheet of nonwoven

fabric either from above or from below, when viewing the sheet of nonwoven fabric in plan view.

[0055] The region of the sheet of nonwoven fabric in which the at least one through-opening is to

be formed may be at least partially thermally compacted prior to punching of the at least one through

opening. As a result, the through-openings can be punched out more precisely. For example, the corre

sponding regions of the sheet of nonwoven fabric may be compacted by means of ultrasound or pre

embossed using a calender.

[0056] The plastic film may be connected to the sheet of nonwoven fabric and to the nonwoven

fabric element. In particular, the plastic film may be connected, in particular welded, to a region of the

sheet of nonwoven fabric surrounding the region free of nonwoven fabric, to the annular region and to

the at least one connection piece of the nonwoven fabric element.

[0057] In addition, the retaining plate may be connected, in particular welded, to the at least one

connection piece of the nonwoven fabric element. As a result, the connection between the retaining

plate and bag wall can be made even more stable.

[0058] The sheet of nonwoven fabric may comprise one or more filter material layers, in particular

one or more nonwoven fabric layers. Filter material layers of this kind are known, for example, from EP

2 011556 and EP 0 960 645. A wide variety of plastics may be used for the nonwoven fabric layers, for

example polypropylene and/or polyester. The bag wall of the vacuum cleaner filter bag may also com

prise recycled plastic. For example, the bag wall may be designed in the manner described in EP 3 219

376 Al.

[0059] The plastic film may comprise one or more of the above-mentioned features.

[0060] The vacuum cleaner filter bag produced in this manner may comprise one or more of the

above-mentioned features.

[0061] Unless the context clearly requires otherwise, throughout the description and the claims,

the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed

to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

Brief Description of the Drawings

[0062] Additional features and advantages of preferred embodiments of the invention will be ex

plained below, by way of example only, with reference to the exemplary figures, in which:

[0063] Fig. 1 shows an illustration of a first step of an exemplary method for producing a

vacuum cleaner filter bag;

[0064] Fig. 2 shows another step of an exemplary method for producing a vacuum cleaner

filter bag;

[0065] Fig. 3 shows another step of an exemplary method for producing a vacuum cleaner

filter bag;

[0066] Fig. 4 shows another step of an exemplary method for producing a vacuum cleaner

filter bag;

[0067] Fig. 5 shows another aspect of an exemplary method for producing a vacuum cleaner

filter bag;

[0068] Fig. 6 shows an exemplary vacuum cleaner filter bag;

[0069] Fig. 7 shows an alternative embodiment of the nonwoven fabric element;

[0070] Fig. 8 shows another alternative embodiment of the nonwoven fabric element; and

[0071] Fig. 9 shows another alternative embodiment of the nonwoven fabric element.

[0072] Fig. 1 shows a first step of an exemplary method for producing a vacuum cleaner filter bag

according to the invention. In this step, by way of example, two through-openings 1, 2 are punched

into a sheet of nonwoven fabric that is moved stepwise in the machine direction (indicated by an ar

row in Fig. 1) during the method. As can be seen in Fig. 1, a nonwoven fabric element 3 that extends in

the machine direction is left between the two through-openings 1, 2. Here, the two through-openings

1, 2 form a region free of nonwoven fabric that comprises the two through-openings 1, 2 as non-con

tiguous sub-regions. The edge of the region free of nonwoven fabric is formed by the two edges of the

through-openings 1, 2. The nonwoven fabric element 3 is arranged between two opposing edge por

tions A, B of the edge of the region free of nonwoven fabric. The nonwoven fabric element 3 is spaced

apart from the edge portions A, B in each case by means of a sub-region of the region free of nonwo

ven fabric, namely by means of the through-opening 1 and 2, respectively.

[0073] When the sheet of nonwoven fabric is moved along further after the through-openings 1, 2

have been punched, it is drawn in the machine direction. In the prior art, in which the nonwoven fabric

element 3 was not provided, this being drawn in the machine direction resulted in a deformation of

the single through-opening provided, which led to disadvantages during further processing. Therefore,

in the prior art, the sheet of nonwoven fabric had to be moved slowly and carefully. However, by virtue

of the nonwoven fabric element 3, the region of the through-openings 1, 2 is stabilized during a tug in

the machine direction, such that higher processing speeds are possible.

[0074] As can also be seen in Fig. 1, the two through-openings 1, 2 are symmetrical with respect to

an axis of symmetry 4 that extends in the machine direction. The region comprising the nonwoven fab

ric element 3 and the through-openings 1, 2 has a rectangular, in particular square, boundary in plan

view.

[0075] In this case, the nonwoven fabric element 3 comprises a central region in the shape of a disc

and two connection pieces that oppose one another in the machine direction and that connect the re

gion in the shape of a disc to parts of the above-mentioned boundary.

[0076] The sheet of nonwoven fabric is merely shown schematically in the present case, in particu

lar the borders 5, 6 thereof extending transversely to the machine direction.

[0077] In another method step illustrated in Fig. 2, a plastic film is connected to the sheet of

nonwoven fabric from underneath the sheet of nonwoven fabric, such that, when the sheet of nonwo

ven fabric is viewed in plan view, the plastic film (as shown in Fig. 2) completely overlaps with the re

gion free of nonwoven fabric and the nonwoven fabric element 3. The points at which the plastic film is

welded to the sheet of nonwoven fabric are indicated in Fig. 2 by means of dashed lines. In particular,

the plastic film can be welded to a part of the sheet of nonwoven fabric which completely surrounds

the region free of nonwoven fabric, i.e. to the above-described boundary of the region comprising the

through-openings 1, 2 and the nonwoven fabric element 3. As a result, the circumferential weld seam 7

shown in Fig. 2 is produced. Optionally, the plastic film may also be connected to the nonwoven fabric

element 3, for example by means of a weld seam 8 that extends in the machine direction.

[0078] In the finished form of the vacuum cleaner filter bag, the regions of the plastic film that are

not overlapped by the nonwoven fabric element 3 form a first sub-region of a film region that, in the

case of a transparent film, serves as a sort of viewing window such that it is possible to visually deter

mine how full the vacuum cleaner filter bag is and, in the case of a non-transparent film, contributes to

easier insertion of the vacuum cleaner filter bag into a corresponding receptacle in the vacuum

cleaner.

[0079] Fig. 3 shows another method step of the exemplary method for producing a vacuum cleaner

filter bag, in which the future fill hole, in particular, is formed in the bag wall. To do this, the nonwoven

fabric element 3 and the plastic film are punched at the same time, such that a through-hole 9 is formed. The simultaneous punching of the nonwoven fabric element 3 and the plastic film is procedur ally advantageous. However, the method according to the invention is not limited to simultaneous punching.

[0080] By punching the through-hole 9, the previously disc-shaped central part of the nonwoven

fabric element 3 is formed into an annular region 10 that is connected via two connection pieces 11, 12

to the rest of the sheet of nonwoven fabric, in particular to the weld seam 7.

[0081] The shape and radial extent of the annular region 10 is adapted to the region of the retain

ing plate which is provided for connection to the bag wall. This region of the retaining plate typically

comprises guides in order to improve welding of the retaining plate to the bag wall.

[0082] Finally, Fig. 4 illustrates the step of connecting the retaining plate 13 to the annular region

and to the plastic film (weld region indicated by a dashed line). Because the retaining plate is con

nected not only to the plastic film but also to the nonwoven fabric element 3, a secure connection be

tween the retaining plate 13 and plastic film is possible.

[0083] As known per se, the retaining plate 13 comprises a sealing lip 14 and a closure cap (closure

cap not shown in Fig. 4). By virtue of the closure cap, vacuumed material can be prevented from escap

ing when the full bag is removed from the vacuum cleaner housing.

[0084] As can be seen in Fig. 4, the retaining plate 13 overlaps with the nonwoven fabric element 3

almost completely, but only partially overlaps with the first sub-region of the film region. As a result,

the first sub-region of the film region can be used as a viewing window in order to check how full the

vacuum cleaner bag is if a transparent plastic film is used. Only small amounts of the connection pieces

11, 12 are visible, but these do not interfere with the function of the viewing window. Ultimately, a re

sult that is comparable to the prior art (comparable, for example, to EP 3 066 968) but having a more

secure connection between the retaining plate 13 and the bag wall is achieved.

[0085] Fig. 5 shows other possible weld regions in which the plastic film can be connected to the

nonwoven fabric element 3. In this case, for example, welding takes place also along the annular ele

ment 10 as well as along the connection pieces 11, 12. The circumferential weld seam 7 is also shown.

Depending on the specific embodiment, the retaining plate 13 may also be connected to connection

pieces 11, 12 if required (in addition to the connection in the region of the annular element 10).

[0086] Finally, a vacuum cleaner filter bag can be assembled by cutting the sheet of nonwoven fab

ric to the appropriate size and for example interconnecting two nonwoven fabric layers by means of a

circumferential weld seam. One of the two nonwoven fabric layers comprises the film region and the

retaining plate. Fig. 6 is a plan view of a simple vacuum cleaner filter bag of this kind. As is known per

se, however, the vacuum cleaner filter bag may have other geometries. For example, side folds may be

provided on the both longitudinal sides and/or transverse sides in order to achieve a smaller packing

size with the same filter surface area.

[0087] Instead of connecting the plastic film from underneath the sheet of nonwoven fabric, as

shown in Fig. 2, the plastic film could be connected to the sheet of nonwoven fabric from above, when

viewing the sheet of nonwoven fabric in plan view. This ultimately results in that the plastic film is ar

ranged between the nonwoven fabric element and the retaining plate in the produced vacuum cleaner

filter bag. The inventors of the present application have found that this configuration also allows for a

more secure connection between the retaining plate and bag wall, since the nonwoven fabric element

in this case forms a softer, more flexible substrate for the welding than the conveyor on which the

sheet of nonwoven fabric otherwise lies.

[0088] Furthermore, it is possible to partially or fully thermally compact, for example by means of

ultrasound or pre-embossing, the regions of the sheet of nonwoven fabric in which the through-open

ings 1, 2 are to be punched (cf. Fig. 1) before the punching. As a result, the punched holes are formed

with more defined borders.

[0089] The geometry of the nonwoven fabric element 3 is shown merely by way of example in Fig.

1. Other examples can be found in Fig. 7 to 9.

[0090] In Fig. 7, the disc-shaped region of the nonwoven fabric element 3 is connected to the rest

of the sheet of nonwoven fabric via four connection pieces, which are arranged in pairs on opposing

sides of the disc-shaped region. This geometry is achieved by punching four through-openings 14, 15,

16, 17, which form the region free of nonwoven fabric. The nonwoven fabric element 3 is arranged be

tween the edge portions A-B, C-D, E-F and G-H.

[0091] In Fig. 8, the disc-shaped region of the nonwoven fabric element 3 is connected to the rest

of the sheet of nonwoven fabric via three connection pieces. Two of the connection pieces form an an

gle of 450 with the machine direction. This geometry is achieved by punching three through-openings

18, 19, 20, which form the region free of nonwoven fabric. The nonwoven fabric element 3 is arranged

between the edge portions A-B, C-D and C-E.

[0092] However, it is also possible to connect the disc-shaped region to the rest of the sheet of

nonwoven fabric via only one connection piece, as shown in Fig. 9. In this case, too, only one through

opening 21 is provided, which forms the region free of nonwoven fabric. The nonwoven fabric element

3 is arranged between the edge portions A and B and is spaced apart from each of these edge portions

A, B in each case by means of a different sub-region of the region free of nonwoven fabric. Again, only

one connection piece is used to simplify the positioning of the nonwoven fabric element 3. This im

proves assembly of the retaining plate.

[0093] It should be understood that features mentioned in relation to the above-described exem

plary embodiments are not limited to specific combinations and, as such, any other desired combina

tions are also possible. In particular, it should be understood that geometries shown in the figures, for

example those of the retaining plate, are merely exemplary and, as such, any other desired configura

tions are also possible.

Claims

1. Vacuum cleaner filter bag comprising a bag wall and a retaining plate which is connected to

the bag wall, wherein the bag wall comprises a film region in which a plastic film is arranged,

wherein the film region comprises a first sub-region

in which the bag wall is formed solely by the plastic film or

in which the plastic film forms the outermost layer of the bag wall,

wherein the film region comprises a second sub-region in which the plastic film is overlapped

by a nonwoven fabric element,

wherein the retaining plate is connected, in particular welded, to the plastic film and the

nonwoven fabric element,

wherein the nonwoven fabric element has at least one part which is connected to the bag wall

part surrounding the film region;

wherein the nonwoven fabric element comprises a through-hole which is arranged concentri

cally with respect to a through-hole in the plastic film and a through-hole in the retaining plate; and

wherein the nonwoven fabric element comprises an annular region that surrounds the

through-hole and that is connected to the bag wall part surrounding the film region via at least one

connection piece, and wherein the retaining plate is connected to the nonwoven fabric element in the

annular region.

2. Vacuum cleaner filter bag according to claim 1, wherein the plastic film is designed to be

transparent or non-transparent.

3. Vacuum cleaner filter bag according to claim 1 or 2, wherein at least two connection pieces

are provided and the two connection pieces connect the annular region to the bag wall part surround

ing the film region on opposing sides of the film region.

4. Method for producing a vacuum cleaner filter bag, comprising the steps of

punching at least one through-opening into a sheet of nonwoven fabric such that a region free

of nonwoven fabric is formed in the sheet of nonwoven fabric and a nonwoven fabric element is left

which is arranged between two opposing edge portions of the region free of nonwoven fabric and

which is spaced apart from the opposing edge portions in each case by means of a sub-region of the

region free of nonwoven fabric; connecting a plastic film to the sheet of nonwoven fabric such that, when the sheet of nonwo ven fabric is viewed in plan view, the plastic film completely overlaps with the region free of nonwoven fabric and the nonwoven fabric element; forming a through-hole in the plastic film and in the nonwoven fabric element; welding a retaining plate to the plastic film and the nonwoven fabric element.

5. Method according to claim 4, wherein two through-openings are punched which are formed

symmetrically with respect to an axis of symmetry that extends in the machine direction, in particular

wherein the through-openings are punched such that the nonwoven fabric element remains between

the through-openings.

6. Method according to claim 4 or 5, wherein the region of the sheet of nonwoven fabric in

which the region free of nonwoven fabric and the nonwoven fabric element are arranged have a rec

tangular, in particular square, boundary.

7. Method according to any of claims 4 to 6, wherein the nonwoven fabric element comprises,

before the through-hole is formed, a region in the shape of a disc and at least one connection piece,

which connects the region in the shape of a disc to the rest of the sheet of nonwoven fabric.

8. Method according to claim 7, wherein the region in the shape of a disc is annular on account

of the formation of the through-hole and wherein the retaining plate is connected, in particular

welded, to the annular region of the nonwoven fabric element.

9. Method according to claim 8, wherein the retaining plate comprises guides which are ar

ranged in a region of the retaining plate surrounding a through-hole of the retaining plate, the radial

extension of which region corresponds to that of the annular region of the nonwoven fabric element.

10. Method according to any of claims 4 to 9, wherein the retaining plate and the plastic film

are arranged such that the nonwoven fabric element is located between the retaining plate and the

plastic film after connection of the retaining plate.

11. Method according to any of claims 4 to 9, wherein the retaining plate and the plastic film

are arranged such that the plastic film is located between the retaining plate and the nonwoven fabric

element after connection of the retaining plate.

12. Method according to any of claims 4 to 11, wherein the region of the sheet of nonwoven

fabric in which the at least one through-opening is to be formed is at least partially thermally com

pacted prior to punching of the at least one through-opening.

13. Method according to any of claims 4 to 12, wherein the plastic film is connected to the

nonwoven fabric element and to a part of the sheet of nonwoven material surrounding the region free

of nonwoven fabric.