METHOD FOR PRODUCING A RESPIRATORY PROTECTION MASK

Abstract

The invention relates to a method for producing a respiratory protection mask (1) comprising a filter material piece (2) made of an air-permeable material, comprising the steps of: providing a first non-woven material; compacting the first non-woven material in regions; bonding the first non-woven material to a second non-woven material in the compacted region.

Claims

1. A method for producing a respiratory protection mask comprising a filter material piece made of an air-permeable material, comprising the steps of: providing a first non-woven material, compacting the first non-woven material in regions, welding the first non-woven material to a second non-woven material in the compacted region.

2. The method according to claim 1, wherein before welding the two non-woven materials, the second non-woven material is compacted in regions.

3. The method according to claim 1, wherein the compacting is carried out by ultrasonic welding, thermal welding or by pressurization.

4. The method according to claim 1, wherein the welding of the non-woven materials is carried out by ultrasonic welding or thermal welding.

5. The method according to claim 1, wherein the two non-woven materials are formed contiguously.

6. The method according to claim 1, wherein at least one of the first and second non-woven materials have a single-layer structure or a multilayer structure.

7. The method according to claim 6 wherein each layer of the at least one of the first and second non-woven materials is a non-woven or a fiber web.

8. The method according to claim 1, wherein at least one of the first non-woven material and the second non-woven material is a three-layer laminate of a meltblown non-woven material between two layers of a spunbond non-woven material.

9. The method according to claim 1, wherein at least one of the first and the second non-woven material comprises or consists of fibers of a virgin plastic and/or of a recycled plastic.

10. The method according to claim 1, wherein the compacting in regions and/or the welding are performed with a sonotrode and an anvil, wherein the sonotrode and/or the anvil have a smooth surface or a textured surface.

11. The method according to claim 1, wherein a thermally reactivatable adhesive is applied in regions, in particular to the compacted region, before welding.

12. The method according to claim 11, wherein the adhesive is applied by means of with a roller or a nozzle.

13. The method according to claim 1, further comprising attaching a fastening strap to the filter material piece, wherein the attaching comprises welding the fastening strap to the filter material piece.

14. The method according to claim 13, wherein attaching the fastening strap comprises compacting the fastening strap and/or the filter material piece in regions, and welding the fastening strap to the filter material piece in the compacted region.

15. A respiratory protection mask obtained by the method according to claim 1.

Description

[0065] The present invention will be explained in more detail by means of the following exemplary embodiments with reference to the figures, without limiting the invention to the specific embodiments shown. In the figures

[0066] FIG. 1 is a schematic illustration of a respiratory protective mask,

[0067] FIG. 2 is a schematic cross-sectional view of the structure of a filter material piece of a respiratory protection mask,

[0068] FIG. 3 is a schematic top view of a respiratory protection mask,

[0069] FIG. 4 a schematic side view of a filter piece of a respiratory protection mask.

[0070] FIG. 1 shows a schematic view of a respiratory protective mask 1 in the form of a half mask. This is an example of a medical face mask. The respiratory protection mask 1 shown includes a filter material piece or filter part 2. The cutting of the filter material piece is basically rectangular, but may also assume other shapes, in particular polygonal shapes.

[0071] In the example shown two fastening straps 3 are attached to the filter material piece 2. In the illustrated embodiment, the fastening straps are provided for fastening to the ears of the wearer.

[0072] For better adaptation to the shape of the face, the respiratory protection mask has a nose bridge 4 that is destructively or non-destructively detachably connected to the filter material piece. In particular, it may be a wire embedded in a plastic material.

[0073] A destructive connection includes, for example, a welding. This may be either continuous along the entire length of the nose bridge or at individual discrete points. Alternatively, the nose bridge may be bonded to the filter material piece. For example, a hot melt may be used for this purpose, which typically also results in a destructive connection.

[0074] In the embodiment, three pleats 5 are introduced into the filter piece or the air-permeable material 2.

[0075] The schematic cross-sectional view of FIG. 2 illustrates the structure of a filter material piece for a respiratory protection mask. A fine filter layer 7 is arranged between two support layers 6. The three layers of this non-woven material may be welded together, in particular along the edges, i.e. the circumference, of the filter piece 2, as illustrated in FIG. 1.

[0076] Alternatively to the structure shown in FIG. 2, the air-permeable material of the respiratory protection mask may include fewer or more layers. For example, only one support layer and one fine filter layer may be provided.

[0077] In one embodiment, the respiratory protection masks have one or more layers of virgin or recycled PET or PP filaments or virgin or recycled PET or PP staple fibers. Regarding the individual filter layers:

[0078] Spunbonded layers of PET or PP (virgin or recycled) with a basis weight of 5 to 50 g/m.sup.2 and a titer of 1 dtex to 15 dtex are particularly suitable as support layers 6. The raw materials used for rPET are, for example, PET waste (e.g. punching waste) and so-called bottle flakes, i.e. pieces of ground beverage bottles. In order to cover the different coloration of the waste, it is possible to dye the recyclate. The HELIX® (Comerio Ercole) process is particularly advantageous as a thermal bonding process for consolidating the spunbond non-woven.

[0079] One or more layers of meltblown PET or PP (virgin or recycled) with a basis weight of 5 to 30 g/m.sup.2 each are used as fine filter layers 7. Some or all of this (these) layer(s) is (are) electrostatically charged. Layers made of rPET or rPP may also be electrostatically charged. The only thing to keep in mind is that no metallized PET waste is then used for production. Alternatively, the meltblown filaments may also consist of bicomponent fibers, in which the core is made, for example, of rPET or rPP and the sheath is made of a plastic that may be particularly well electrostatically charged (e.g. virgin PP, PC, PET or rPP, in particular chemically recycled).

[0080] The filaments or staple fibers may also be made of bicomponent materials, in which the core is formed of rPET or rPP and the sheath is formed of a plastic that may be particularly well electrostatically charged (e.g. virgin PP, PC, PET or rPP).

[0081] Specifically, the filter material piece may be made of a three-layer air-permeable material. In this case, a meltblown non-woven layer with a grammage of 20 g/m.sup.2 is arranged between two spunbond non-woven layers of virgin PET or rPET, The SMS thus obtained may be ultrasonically welded by a weld seam running along the edges.

[0082] The meltblown may be electrostatically charged by the addition of additives and a water jet treatment (hydrocharging), as described for example in WO 97/07272.

[0083] Alternatively, the meltblown may have a grammage of 25 g/m.sup.2 and have been electrostatically charged by means of a corona treatment.

[0084] The meltblown may include bicomponent fibers having a core of rPP and a sheath of virgin PP. Alternatively, the sheath may also include rPP. The meltblown may be produced, for example, with a meltblown machine from Hills Inc. of West Melbourne, FL, USA. This allows high recycled content to be achieved despite electrostatic charging.

[0085] The SMS may be creped. To this end, in particular, the Micrex micro-creping process may be used. Purely by way of example, reference is made to WO 2007/079502. The increase in surface area achieved in this way not only results in a softer appearance, but it may also be better adapted to the shape of the face and absorbs moisture more efficiently.

[0086] The multilayer air-permeable material may be joined by means of a two-step process—as described above. In this process, one, several or all non-woven layers are pre-compacted region-by-region (in the later welding region) and then welded.

[0087] The compaction may be performed by ultrasonic welding, thermal welding or by pressurization. Welding of the non-woven layers may be carried out by ultrasonic welding or thermal welding.

[0088] FIG. 3 shows a schematic top view of an air-permeable material 8 corresponding to the filter part 2 of FIG. 1. However, in comparison with FIG. 1, FIG. 3 shows the rear side of the filter part, i.e. the side facing a user.

[0089] In the illustrated example, a fastening strap 9 is arranged on each of the opposite edges of the air-permeable material 8, extending over the entire length of the edge. The fastening straps may thus extend together with the air-permeable material during manufacture of the filter part and be cut together with the latter. In the example shown, the fastening strap and the air-permeable material are joined by means of a respective welding point 10 at the opposite end regions of each fastening strap 9.

[0090] For the fastening strap, for example, a TPU laminate consisting of a TPU foil with a thickness of 20 μm to 100 μm and a TPU meltblown (grammage: 20 to 80 g/m.sup.2) is used, which is welded to the filter material piece. The TPU used is in each case in the form of a plastic recyclate.

[0091] The ends of the fastening straps are also attached to the filter material piece in the two-stage process described above. First, the filter material piece in particular, and if necessary also the fastening straps, are pre-compacted in the regions to be welded later. For this purpose, the respective material is subjected to pressure or treated with ultrasound. This is followed by the actual welding step.

[0092] The PP material produced by the Vistamaxx process may be manufactured by the meltblown or foil casting or blown foil process and laminated—as described for the TPU laminate.

[0093] FIG. 4 shows a schematic side view of a filter part of a respiratory protection mask. The filter part includes two filter material pieces 11, only one of which is shown in FIG. 4.

[0094] Both pieces of filter material have a hexagonal shape and fit exactly on top of each other. Thus, the filter part formed by the filter material pieces 11 welded together also has a hexagonal shape as such (in the finished but unused state).

[0095] The edge on the left side lies between two right angles, and is thus bounded by two edges parallel to each other and perpendicular to the edge between them.

[0096] The air-permeable material of both filter material pieces is creped. The creping direction is also indicated here by the hatching; the creping folds extend substantially horizontally in the intended use of the respiratory protection mask made from the filter piece.

[0097] Each of the two filter material pieces 11 is configured in the form of an SMS, as explained, for example, in connection with FIG. 2. In this case, the three layers of a filter material piece have first been welded together along the edge between the two right angles, on the left side in the figure. The corresponding weld seam 12 of the filter material piece 11 shown extends in parallel to the left edge.

[0098] The weld seam 13 along the remaining five edges is a welding of connecting the two filter material pieces together. At these edges, there is no separate welding of the SMS layers of a filter material piece as such. On the side of the weld seam 12, however, the two filter material pieces are not welded together. This forms the open side of the respiratory protection mask, which will face the wearer's face.

[0099] During manufacture, therefore, the three layers of SMS in the form of non-woven webs are first laid loosely on top of each other and welded together along one edge by means of weld seam 12. The other five edges remain open, i.e. the layers are loose. In the arrangement shown in FIG. 4, the machine direction of the production machine extends from top to bottom, parallel to the weld seam 12. The SMS filter material web welded on one side only is then creped as a whole, the creping direction, i.e. the direction of the crepe folds, being transverse, i.e. essentially perpendicular to the machine direction or weld seam 12.

[0100] Subsequently, two such creped SMS filter material webs are arranged over each other in the machine direction, i.e. in the direction of or parallel to the weld seam 12, so that they come to lie on top of each other. The two SMS filter material webs, i.e. the total of six layers of two SMS, are welded together along weld seam 13, which forms five edges of the two superimposed filter material pieces. Along these edges, the two filter material webs are punched, so that a filter part 11 is then obtained as shown in FIG. 4.

[0101] The two SMS filter material webs, i.e. the two non-woven materials, are welded together using the two-stage process. The region with the reference sign 13 is first pre-compacted. In this example, pre-compaction is performed by pressurization at room temperature. A thermal or ultrasonic welding device may be used for this purpose, with the latter merely compressing the non-woven material at room temperature without introducing thermal or ultrasonic energy. The additional introduction of thermal or ultrasonic energy during pre-compaction is also possible, whereby the corresponding total energy input by pre-compaction and welding is still lower in sum than a single-stage pure welding for a weld seam of the same strength. For example, the sum of pre-compaction time and welding time is less than would be required to achieve the same strength with a single-stage pure welding step.

[0102] An optional layer of hot melt may then be applied in the region, which is then allowed to cool. After cooling, thermal welding takes place, in which case only the melting temperature of the hotmelt needs to be reached. Alternatively, instead of applying hotmelt, only an ultrasonic welding step may take place.

[0103] The pre-compaction region is larger in the plane of the non-woven material than the later welding region. In particular, it may have a greater extension longitudinally and/or transversely to the machine direction. The larger pre-compaction region ensures that the subsequent application of thermal or ultrasonic energy falls within the pre-compacted region even if there are tolerances in the process parameters (e.g. fluctuations in the transport path between the pre-compaction station and the welding station, angular offset of the sonotrode, etc.).

[0104] The two-stage nature of the manufacturing process may be demonstrated microscopically, for example. A perfect match between the pre-compacted region and the welded region is virtually impossible to achieve, so that cross-sectional views regularly show a thickness jump between a sub-region that has only been pre-compacted and a welded region.

[0105] The resulting respiratory protection mask is advantageously stretchable, especially on its open side, i.e. in the area of the weld seam 12, which allows good face adaptation. In addition, due to the creping, the air permeability is also high and the breathing resistance is low.

[0106] Even though in the example described the filter material piece is composed of two non-woven materials, it is alternatively also possible to use two contiguous non-woven materials in the form of a common non-woven material piece. This is folded at the vertical edge located on the right in the figure, so that two hexagonal contiguous areas are then superimposed. The remainder of the two-stage welding process proceeds as described above.

[0107] Comparative tests have shown the advantages of such two-stage joining. A three-layer material was used, in which a meltblown non-woven layer with a basis weight of 33 g/m.sup.2 was sandwiched between two spunbond non-woven layers with a basis weight of 35 g/m.sup.2. The three-layer material was used as a single piece of non-woven material for manufacturing the mask; thus, two separate non-woven materials were not used.

[0108] In this comparative test, all layers consisted of virgin PP, but the same applies to recycled materials. These three layers were first pre-compacted by means of pressure in the later welding region, whereby the pre-compaction was only carried out on one side of the piece of material to be subsequently folded and superimposed.

[0109] Then the actual welding was carried out with the parameters given below. During welding, two sections of the coherent non-woven material lay one on top of the other, with one region being pre-compacted in the section lying above or below (non-woven material), but not in the section lying below or above, i.e. in the second non-woven material.

TABLE-US-00001 Welding time [ms] 53 60 70 80 Energy input [J] 30 40 50 60 Pressure [bar] 1.8 1.8 1.8 1.8 Strength [N] 14.2 18.1 27.8 54.4

[0110] The diameter of the feed cylinder of the sonotrode, to which the pressure specification refers, is 80 mm.

[0111] It is evident that even at a welding time of 53 ms, the tensile strength of the welded joint is 14.2 N, which almost corresponds to the 15 N typically required for respiratory protection masks. Even with a welding time of 60 ms and a corresponding energy input of 40 J, the tensile strength is over 18 N.

[0112] In comparison, the welding time for the laminate without the pre-compaction with higher energy input is 320 ms:

TABLE-US-00002 Welding time [ms] 320 Energy input [J] 140 Pressure [bar] 2 Strength [N] 18.2