PVDF FILTERING FACE-PIECE RESPIRATOR AND RECYCLING METHOD

1 . A respiratory protection mask made from polyvinylidene fluoride and having the following structure:

an inner layer of nonwoven PVDF,

a central PVDF layer composed of a support layer made from PVDF and an electrospun layer of PVDF nanofibers,

an outer layer of nonwoven PVDF,

a PVDF nose bridge, and

PVDF retaining straps.

2 . The mask as claimed in claim 1 , wherein said inner layer is a nonwoven PVDF and has a grammage of between 20 and 100 g/m 2 .

3 . The mask as claimed in claim 1 , wherein said support layer is a nonwoven PVDF and has a grammage of between 20 and 100 g/m 2 .

4 . The mask as claimed in claim 1 , wherein said support layer is a PVDF produced by extrusion spinning.

5 . The mask as claimed in claim 1 , wherein said electrospun layer of PVDF nanofibers comprises at least one of: a PVDF homopolymer; a mixture of two PVDF homopolymers; a copolymer comprising vinylidene difluoride (VDF) units and one or more types of units of comonomers compatible with vinylidene difluoride; a mixture of a PVDF homopolymer and of a VDF copolymer; or a mixture of two VDF copolymers.

6 . The mask as claimed in claim 5 , wherein said comonomer compatible with VDF is selected from the group consisting of: vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, trifluoropropenes, tetrafluoropropenes, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropenes, perfluoroalkyl vinyl ethers of the general formula Rf-O-CF-CF2, Rf being an alkyl group, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene and chlorotrifluoropropene.

7 . The mask as claimed in claim 1 , wherein the mean thickness of the layer of PVDF nanofibers is from 0.1 µm to 100 µm.

8 . The mask as claimed in claim 1 , wherein, when said layer of nanofibers is composed of a mixture of two constituents, the proportion by mass between them ranges from 1:99 to 99:1.

9 . The mask as claimed in claim 1 , wherein said PVDF nanofibers have a mean fiber diameter Dv50 of between 30 and 500 nm.

10 . The mask as claimed in claim 1 , wherein said outer layer of nonwoven PVDF has a grammage of between 10 and 60 g/m 2 .

11 . The mask as claimed in claim 1 , wherein said retaining straps are adjustable loops produced by injection molding or 3D printing or elastic bands based on PVDF textile.

12 . A method for manufacturing the mask as claimed in claim 1 , said method comprising the following steps:

providing a first layer of nonwoven PVDF, intended to constitute the outer and inner layers;

providing a second layer of PVDF, the latter being chosen from nonwoven polymer or polymer obtained by extrusion spinning, intended to constitute the support layer of the central layer;

depositing on said support layer, via an electrospinning process, a layer of PVDF nanofibers;

inserting a nose bridge composed of a mixture of PVDF homopolymer and of a VDF copolymer, and

welding, PVDF retaining straps onto the body of the mask, at the ends.

13 . A method for reconditioning the mask as claimed in claim 1 , said method implementing a technique chosen from:

treatment with a solution of hydrogen peroxide at a concentration of less than 8%;

treatment with UV-C with an energy of greater than or equal to 1 J/cm 2 ; or

treatment with dry or wet heat at a temperature of greater than or equal to 60° C.

14 . A method for recycling used PVDF respiratory protection masks, said masks having the structure as claimed in claim 1 , said method comprising the following steps:

grinding the masks to result in the obtaining of flakes,

granulating said flakes to result in the obtaining of PVDF granules, and

using said granules for the transformation of the PVDF via a molten or solvent-based route.