Face mask

Abstract

The invention relates to a face mask comprising a compound structure with an inner layer and two sandwich layers, wherein the inner layer is made from a filter material for filtering particles and germs, the sandwich layers are made from a textile material, the inner layer is sandwiched by the sandwich layers, and the sandwich layers are bonded to the inner layer at least in sections along the perimeter of the face mask and in sections in the inner area of the face mask. In this way, a reusable face mask with enhanced filtration efficiency is provided.

Claims

1. A face mask comprising a compound structure with an inner layer and two sandwich layers, wherein the inner layer is made from a filter material for filtering particles and germs, the sandwich layers are made from a textile material, the inner layer is sandwiched by the sandwich layers, and the sandwich layers are bonded to the inner layer in an inner area of the sandwich layers by application of a heat and pressure treatment over the entire surface on which they lie next to each other.

2. The face mask according to claim 1, wherein the sandwich layers are additionally bonded to the inner layer in the inner area of the sandwich layers by ultrasound bonding.

3. The face mask according to claim 2, wherein the sandwich layers are bonded to the inner layer along ultrasound bonding rows which run through the inner area of the face mask from one point on the perimeter to another point of the perimeter.

4. The face mask according to claim 3, wherein the ultrasound bonding rows are comprised of ultrasound bonding connections of the sandwich layers with the inner layer, the ultrasound bonding connections of one ultrasound bonding row being arranged at a distance from each other.

5. The face mask according to claim 4, wherein the ultrasound bonding rows are arranged as pairs of ultrasound bonding rows; the pairs of ultrasound bonding rows are parallel to each other and have a distance between the ultrasound bonding rows comprising the pair that is smaller than the distance between the next pair of ultrasound bonding rows.

6. The face mask according to claim 4, wherein the ultrasound bonding rows are arranged as single ultrasound bonding rows which run parallel to each other and which are equally spaced from each other.

7. The face mask according to claim 1, wherein the inner layer is made from a melt-blown non-woven material.

8. The face mask of claim 7, wherein the melt-blown non-woven material is a melt-blown polypropylene non-woven material.

9. The face mask according to claim 1, wherein the sandwich layers are made from spun bonded polypropylene non-woven material.

10. The face mask according to claim 9, wherein the weight of each of the sandwich layers is in the range from 0.01 kg/m.sup.2 to 0.1 kg/m.sup.2.

11. The face mask according to claim 1, wherein the compound structure is sandwiched between two outer layers made of textile material.

12. The face mask according to claim 11, wherein the textile material of the two outer layers is woven or knitted, and the textile material of the outer layers is made of natural or synthetic fiber.

13. The face mask according to claim 1, wherein at least one of the sandwich layers or the inner layer comprises an antimicrobial fabric finish.

14. The face mask according to claim 1, wherein an outer layer that covers the face mask to the outside comprises a water repellant fabric finish.

15. A face mask comprising a compound structure with an inner layer and two sandwich layers, wherein the inner layer is made from a melt-blown polypropylene non-woven material for filtering particles and germs, the sandwich layers are made from a spun bonded polypropylene non-woven material, the inner layer is sandwiched by the sandwich layers, and wherein the weight of each sandwich layers is in the range from 0.01 kg/m.sup.2 to 0.1 kg/m.sup.2, and wherein the compound structure is sandwiched between two outer layers which made of a textile material, wherein the sandwich layers are bonded to the inner layer in an inner area of the sandwich layers by application of a heat and pressure treatment over the entire surface on which they lie next to each other.

16. The face mask of claim 1, wherein the filter material for filtering particles and germs is different from the textile material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically depicts a three-dimensional exploded view of a face mask according to a preferred embodiment of the invention;

(2) FIG. 2A schematically depict the structure of the inner part of a face mask according to a preferred embodiment of the invention before bonding with heat and pressure;

(3) FIG. 2B schematically depict the structure of the inner part of a face mask according to a preferred embodiment of the invention after bonding with heat and pressure;

(4) FIG. 3A schematically depict the structure of the inner part of a face mask according to a preferred embodiment of the invention before ultrasound bonding;

(5) FIG. 3B schematically depict the structure of the inner part of a face mask according to a preferred embodiment of the invention after ultrasound bonding;

(6) FIG. 4A schematically depict the structure of pairs of ultrasound bonding rows which run through the inner area of the face mask according to one preferred embodiment of the invention;

(7) FIG. 4B schematically depict the structure of pairs of ultrasound bonding rows which run through the inner area of the face mask according to another preferred embodiment of the invention;

(8) FIG. 4C schematically depict the structure of pairs of ultrasound bonding rows which run through the inner area of the face mask according to yet another preferred embodiment of the invention;

(9) FIG. 4D schematically depict the structure of pairs of ultrasound bonding rows which run through the inner area of the face mask according to another preferred embodiment of the invention;

(10) FIG. 5A schematically depict the structure of single ultrasound bonding rows which run through the inner area of the face mask according to one preferred embodiment of the invention;

(11) FIG. 5B schematically depict the structure of single ultrasound bonding rows which run through the inner area of the face mask according to another preferred embodiment of the invention; and

(12) FIG. 5C schematically depict the structure of single ultrasound bonding rows which run through the inner area of the face mask according to yet another preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(13) From FIG. 1 which schematically depicts a three-dimensional exploded view of a face mask 1 according to a preferred embodiment of the invention, it can be seen that the face mask comprises a 5-layer structure: The face mask 1 comprises a compound structure with an inner layer 2 and two sandwich layers 3. While the inner layer 2 is made from a filter material for filtering particles and germs, the sandwich layers 3 are made from a textile material. As shown in FIG. 1, the inner layer 2 is sandwiched by the sandwich layers 3. In addition, as explained in more detail further below, the sandwich layers 3 are stitched to the inner layer 2 in sections along the perimeter of the face mask 1. Further, the sandwich layers 3 are bonded to the inner layer 2 in the inner area of the face mask 1 by heat and pressure as well as by ultrasound bonding.

(14) This structure of the inner layer 2 which is sandwiched by the sandwich layers 3 is covered from both sides by outer layers 4 which are made from a textile material. The textile material of these outer layers 4 may be woven or knitted, and the textile material of the outer layers may be made of natural or synthetic fiber. Further, both of the sandwich layers 3 comprises an antimicrobial fabric finish, and the outer layer 4 which covers the face mask 1 to the outside comprises a durable water repellant fabric finish. Furthermore, for good fit of the face mask 1, a flexible nose bridge 5 is provided. For holding the face mask 1 in the face of the wearer, ear loops 6 which made from a flexible material are provided.

(15) The inner layer 2 is designed in such a way that it shows a particle filtration efficiency (PFE) of more than 99% for particles with a particle size of 0.3 m, wherein the PFE is determined according to the ASTM F2299 standard and wherein the PFE relates to the inner layer 2 of the unwashed face mask 1. As mentioned above, the ASTM F2299 standard refers to a particle size of 0.1 m for testing. However, according to this preferred embodiment of the invention, a particle size of 0.3 m is used for measuring PFE performance but otherwise the test procedure shall fully follow ASTM F2299.

(16) Further, the material of the inner layer 2 shows a bacterial filtration efficiency (BFE) of more than 99% for particles with a particle size of 3 m at a flow rate of 28.3 l/m, wherein the BFE is determined according to the ASTM F2101 standard and wherein the BFE relates to the filter of the unwashed face mask. Furthermore, the material of the inner layer 2 shows a differential pressure of less than 5 mm H.sub.2O at an average air flow of 8 l/min, wherein the differential pressure is determined according to the EN14683 standard (Annex C) and wherein the differential pressure relates to the inner layer 2 of the unwashed face mask 1. In this respect, according to the preferred embodiment of the invention described here, the inner layer 2 is made from a melt-blown polypropylene non-woven material. According to this preferred embodiment of the invention, the sandwich layers 3 are made from spun bonded polypropylene non-woven material in light weight, i.e. with a weight in the range from 0.01 kg/m.sup.2 to 0.1 kg/m.sup.2.

(17) According to the preferred embodiments of the inventions described here, there are two methods for bonding the sandwich layers 3 to the inner layer 2 in sections along the perimeter of the face mask 1 and in sections in the inner area of the face mask 1, namely a) bonding the sandwich layers 3 to the inner layer 2 by a heat and pressure treatment, especially over the entire surface on which they lie next to each other; and, in the alternative, and b) bonding the sandwich layers 3 are to the inner layer 2 by ultrasound bonding, especially along ultrasound bonding rows which run through the inner area of the face mask from one point on the perimeter to another point of the perimeter.

(18) A very high washing durability is achieved when these two methods are combined.

(19) Method a) is schematically depicted in FIGS. 2A and 2B, wherein FIG. 2A shows a cross-sectional schematic view of the inner layer 2 and the sandwich layers 3 before bonding, and FIG. 2B shows a cross-sectional schematic view of the inner layer 2 and the sandwich layers 3 after bonding. According to the preferred embodiment of the invention described here, this bonding process is performed with a temperature in the range between 95 and 130 C. and with pressures in the range of 1 to 15 N/cm.sup.2. As schematically depicted in FIG. 2B, this bonding by heat and pressure leads to continuous two-dimensional heat and pressure bonds 7 between the inner layer 2 and the sandwich layers 3, respectively.

(20) Method b) is schematically depicted in FIGS. 3A and 3B, wherein FIG. 3A shows a cross-sectional schematic view of the inner layer 2 and the sandwich layers 3 before ultrasound bonding, and FIG. 3B shows a cross-sectional schematic view of the inner layer 2 and the sandwich layers 3 after ultrasound bonding. This ultrasound bonding process is similar to the method for fixing ear loops to conventional surgical face masks. In this way, ultrasound bonds 8 between the inner layer 2 and the sandwich layers 3, respectively, at respective bonding spots are achieved which fix the inner layer 2 and the sandwich layers 3 together. Between these ultrasound bondings 8, the inner layer 2, in general, may be loose from the sandwich layers 3. However, as mentioned above, a very high washing durability of the mask is achieved if methods a) and b) are combined. Then, the inner layer 2 is also bonded to the sandwich layers 3 in the areas between the ultrasound bondings 8, i.e. due to the heat and pressure bonding.

(21) As schematically depicted in FIGS. 4A to 4D, in the sandwich structure 9, which is comprised of the sandwich layers 3 and the inner layer 2, the sandwich layers 3 are bonded to the inner layer 2, along ultrasound bonding rows 10, 11 which run through the inner area of the face mask from one point on the perimeter to another point of the perimeter of the face mask 1 in horizontal and vertical direction, respectively. FIGS. 4A to 4D respectively, only show part of a complete face mask 1. Therefore, the perimeter of the face mask 1 is not depicted in FIGS. 4A to 4D. The ultrasound bonding rows 10, 11 are arranged as pairs of ultrasound bonding rows 10, 11 which are parallel to each other and which have a distance from each other which is smaller than the distance of one ultrasound bonding row 10, 11 of the pair of ultrasound bonding rows 10, 11 to the next closer ultrasound bonding row 10, 11 of another pair of ultrasound bonding rows 10, 11. All pairs of ultrasound bonding rows 10, 11 run parallel to their neighboring pairs of ultrasound bonding rows 10, 11. FIGS. 4A to 4D show a compound structure 9 in which the distance between neighboring ultrasound bonding rows is approx. 1.27 cm, 2.54 cm, 3.81 cm and 5.08 cm, respectively.

(22) Further, as schematically depict in FIGS. 5A to 5C, also single ultrasound bonding rows which run through the inner area of the face mask may be used according to different preferred embodiments of the invention. In FIG. 5A, the rows run diagonally through the sandwich structure 9 while in FIGS. 5B and 5C the rows run vertically and horizontally through the sandwich structure. For the sake of clarity, in FIGS. 5A to 5C reference signs for these rows of ultrasound bondings are omitted. From FIGS. 4A to 4D and from FIGS. 5A to 5C, it can be seen that ultrasound bondings are provided in almost the complete area of the sandwich structure 9, i.e. in the area in which the inner layer 2 is sandwiched by the sandwich layers 3.

(23) While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word comprising does not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope. Further, for the sake of clearness, not all elements in the drawings may have been supplied with reference signs.

REFERENCE SYMBOL LIST

(24) face mask 1 inner layer 2 sandwich layers 3 outer layers 4 flexible nose bridge 5 ear loops 6 heat and pressure bonds 7 ultrasound bonds 8 compound structure 9 ultrasound bonding rows 10 ultrasound bonding rows 11