COMPOSITE MEMBRANE COMPRISING A FLUORINATED POLYMER OR SILICONE SURFACE LAYER CONTAINING SILVER, METHOD FOR THE PRODUCTION THEREOF AND USE THEREOF AS A VIRUCIDE

Abstract

A composite membrane including at least one fabric, the membrane including a surface polymer layer, the surface polymer layer including silver and at least one polymer selected from the group formed by fluorinated polymers and silicones, and the membrane being such that silver is in the form of silver supported by a mineral matrix in powder form, the particle size of the matrix being strictly larger than 0.1 μm and strictly smaller than 20 μm. A method for manufacturing a membrane according to the invention. A use of a membrane according to the invention as a virucide.

Claims

1. A composite membrane, said membrane comprising at least one fabric, said membrane comprising a surface polymer layer, said surface polymer layer comprising silver and at least one polymer selected from the group formed by fluoropolymers and silicones, and said membrane being such that the silver is in the form of silver supported by a mineral matrix in powder form, a particle size of the matrix being strictly larger than 0.1 μm and strictly smaller than 20 μm.

2. The composite membrane according to claim 1, such that it comprises at least one intermediate polymer layer the polymer of the intermediate polymer layer in contact with the surface polymer layer and the the polymer of the surface polymer layer being both silicones, or both fluorinated polymers.

3. The composite membrane according to claim 2, such that the surface polymer layer has an average thickness comprised within an interval from 0.5 to 20 μm.

4. The composite membrane according to claim 1, such that the surface polymer layer has an average thickness comprised within an interval from 5 to 100 μm.

5. The composite membrane according to claim 1, such that a silver content by weight in the polymer layer is comprised within an interval from 0.00001 to 10%.

6. The composite membrane according to claim 1, such that the silver is in the form of silver supported by a mineral matrix in powder form, the particle size of the matrix being strictly larger than 0.1 μm and strictly smaller than 5 μm.

7. The composite membrane according to claim 1, such that the fabric is selected from wovens, nonwovens, grids, knits, and mixtures thereof.

8. The composite membrane according to claim 1, such that the fabric is made of textile material and includes yarns or fibres based on a material selected from the group formed by glass, polyesters, polyamides, polyacrylates, viscoses, nylons, cottons, polyvinyl acetates, polyvinyl alcohols and mixtures thereof.

9. The composite membrane according to claim 1, such that the polymer layer further comprises at least one additive selected from among UV stabilisers, matting agents, heat stabilisers, flame-retardant compounds and pigments.

10. A method for manufacturing the composite membrane according to claim 1, comprising the following steps: (a) providing a coated membrane comprising the at least one fabric coated over at least one face with at least one polymeric intermediate layer; (b) providing a polymer composition comprising at least one solvent, the at least one polymer, and the silver; (c) depositing over the at least one face coated during step (a) of a surface layer of the polymer composition of step (b), over a given thickness; and (d) drying the surface polymer layer of step (c), leading to an obtaining of the composite membrane.

11. The method according to claim 10, such that the solvent is selected from the group formed by water, ketones, alcohols, cyclic alcohols, acetates, ketone alcohols, cyclic ethers, aromatic solvents, hydrocarbon solvents, and mixtures thereof.

12. The method according to claim 10, such that step (c) is performed by impregnation, an average thickness of the polymer layer being comprised within an interval from 5 to 100 μm.

13. The method according to claim 10, such that step (c) is performed by coating, an average thickness of the polymer layer being comprised within an interval from 0.5 to 20 μm.

14. The composite membrane according to claim 1, said membrane being configured for use as a virucide.

15. The method according to claim 10, such that step (c) is performed by impregnation, an average thickness of the polymer layer being comprised within an interval from 5 to 50 μm.

16. The method according to claim 10, such that step (c) is performed by coating, an average thickness of the polymer layer being comprised within an interval from 2 to 10 μm.

17. The composite membrane according to claim 2, such that the surface polymer layer has an average thickness comprised within an interval from 2 to 10 μm.

18. The composite membrane according to claim 1, such that the surface polymer layer has an average thickness comprised within an interval from 5 to 50 μm.

19. The composite membrane according to claim 1, such that a silver content by weight in the polymer layer is comprised within an interval from 0.001 to 3%.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0070] The way in which the invention is implemented, as well as the advantages arising therefrom, will come out from the description of the following embodiments, with reference to the appended FIGS. 1 to 4, wherein:

[0071] FIG. 1 is a schematic sectional view of a first embodiment of the membrane of the invention.

[0072] FIG. 2 is an enlargement of FIG. 1.

[0073] FIG. 3 is a schematic sectional view of a second embodiment of the membrane of the invention.

[0074] FIG. 4 is an enlargement of FIG. 3.

[0075] FIG. 5 is a photograph captured by transmission electron microscopy (or TEM) of powder particles of an embodiment according to the invention.

[0076] The micrometric dimension of such particles could be seen.

[0077] Of course, the dimensions and proportions of the elements illustrated in FIGS. 1 to 4 have been exaggerated relative to reality, and have been given only for the purpose of facilitating understanding of the invention.

[0078] The composite membrane 1 of FIG. 1 comprises a textile core or reinforcement 2 consisting of a weave made of high tenacity polyester yarns, formed of warp yarns 22 intersecting with weft yarns 21 and 23. According to the invention, the woven core 2 has been coated over both of its faces with two layers of polymer such as silicone respectively 41 and 42 on each face, the layer 42 being enlarged in FIG. 2. The layer 42 comprises a matrix in powder form 4 comprising silver particles, said powder being dispersed within the layer 42.

[0079] The composite membrane 10 of FIG. 3 comprising the same textile core or reinforcement 2. Afterwards, the woven core 2 has been on its two faces with two successive layers of polymer such as silicone respectively 34 then 36 over one face and 33 then 35 over the other face. According to the invention, two layers respectively 44 and 43 have been deposited over each coated face, the layer 43 being enlarged in FIG. 4. The layer 43 comprises a matrix in powder form 40 comprising silver particles, said powder being dispersed within the layer 43.

EXAMPLES

[0080] Different tests have been carried out on the same composite membrane which is a high-tenacity polyester fabric which is coated with a surface polymer layer (either PVDF or silicone), for each of the three varnishes of the examples. All tests have also been performed on a comparative composite membrane, i.e. a membrane containing no silver.

Example No. 1

[0081] The varnish, made by simple mixing, had the following composition (in parts by weight): Aqueous silicone dispersion from the company Elkem TCS 7110A® (91%) and TCS 7110B® (9%): 100

[0082] Silver: product Viroblock®NPJ03 from the company HEIQ: 20 (such that the average size of the reaction mass agglomerates (titanium dioxide-silver chloride) is about 1.56±71 μm).

Example No. 2

[0083] The varnish, made by simple mixing, comprised an aqueous dispersion of a PVDF-acrylic copolymer with the trade name Kynar Aquatec® FMA 12 from the company ARKEMA and of the silver product Viroblock®NPJ03 from the company HEIQ in the following proportions (parts by weight):

[0084] Aquatec®FMA12: 100

[0085] Silver: product Viroblock®NPJ03 from the company HEIQ: 20

Example No. 3

[0086] The used silver was in powder form (phosphate glass matrix), a commercial product Sanitized® BCA 2141 from the company Sanitized, photographed in TEM in FIG. 5.

[0087] The varnish comprised a solvent-based silicone varnish, Elastosil®RD 6620 F, from the company Wacker, formulated with the crosslinking compounds and catalysts recommended by the manufacturer; to which 3% of BCA 21-41 have been added.

[0088] Test Demonstrating the Weldability and Manufacture of the Composite Membranes According to the Invention.

[0089] Tests have been carried out on a high-frequency bench and/or industrial heating press, to verify that the hold of the polymers on the fabric has been sufficient.

[0090] The silicone composite membranes have been assembled using a HVE (hot-vulcanisable elastomer) type filler band. The PVDF composite membranes have been assembled either at hot temperature (heating press) or by high frequency depending on the grade. After this high-frequency or thermal assembly, with or without a filler band, the force necessary to open the weld according to the protocol described in the standard EN 15619 Appendix C.

[0091] The obtained value should to be equal to or greater than the value 20N over a width of 5 cm in order to guarantee enough strength of the assemblies and sealing.

[0092] Test of Activity Against Viruses

[0093] Preliminary tests that allow verifying the feasibility of the test:

[0094] cell cytotoxicity control

[0095] membrane residual activity control.

[0096] Controls carried out during the tests:

[0097] cell cytotoxicity control

[0098] membrane residual activity control

[0099] stainless steel disc 304 positive control

[0100] The virological analyses are carried out by determining the infectious titres on MRCS cells (ATCC CCL-171) in limit dilution. The readings of the cytopathogenic effects (CPEs) are collected after 6 days of incubation at 37° and 5% CO2.

[0101] The test has been performed in comparison with a reference coated membrane, i.e. a membrane containing no silver.

[0102] The human coronavirus HCoV-229E which is part of the family of enveloped alpha coronaviruses has been used in the test.

[0103] The time of contact between the membrane (comparative or according to the invention) and the solution containing the virus is 60 min.

[0104] Two environmental conditions have been tested:

[0105] Standardised cleanliness condition in the medical field 0.3 g/l BSA;

[0106] Complex interference condition: saliva and respiratory mucus.

[0107] The solution comprising the virus has been deposited in an amount of 50-100 μL and the deposited amount of virus has been 105 TCID50 (standing for 50% Tissue Culture Infectious Dose: titre required to cause infection in 50% of the inoculated cell cultures).

[0108] In comparison with the comparative membrane (without silver), the results have been, for each composite membrane according to the invention, a reduction of more than 90% of the viral load at 60 min of contact, whether for the virus alone or for the virus with mucus and saliva.

[0109] Compliance has been established for a value strictly higher than 90% after 1 h of contact with no mucus or saliva. Consequently, the tests have demonstrated the antiviral function of the composite membranes according to the invention.

[0110] Test for Stability and Resistance to Isopropanol by the Loss of Weight

[0111] Objectives: Replicate in the laboratory a cleaning of the materials with isopropanol. Assessment of the mass losses of different products in isopropanol (CAS No. 67-63-0)

[0112] Description of the test:

[0113] Cut a sample with a size 3*3 cm: 9 cm.sup.2, weigh it using a precision balance, then place it in the glass flask and immerse it in about 50 mL of isopropanol. Close the vial.

[0114] Wait for the time required for the measurement: between 15 minutes and 2 hours

[0115] After the desired time, place the sample in the oven at 60° C. for 5 minutes twice (5 minutes per face to evaporate the isopropanol).

[0116] Weigh the sample again.

[0117] The sample has been placed so as to be totally immersed in isopropanol.

[0118] Calculation of mass losses:

[00001]$\%\mathrm{mass}\mathrm{loss}=\frac{M\mathrm{final}-M\mathrm{initial}}{M\mathrm{initial}}$

[0119] Thus, the obtained mass loss values allow plotting the mass loss of each tested material over time. This test has allowed assessing the resistance of the materials to cleaning with disinfectants including isopropanol. The result has been considered to be “good” if the weight loss did not exceed 5% by weight of the composite membrane and if the appearance and the flexibility of the membrane have not been modified.

[0120] Tests of Cleanability of the Composite Membrane According to the Invention

[0121] The betadine and eosin stain resistance of the composite membranes according to the invention has been tested according to the following procedure:

[0122] Measure the initial colour of the fabric and record it

[0123] Take a non-woven cloth as used in hospital environments

[0124] Impregnate with betadine or eosin using the cloth and spread over the fabric. Let “dry” for 10 minutes.

[0125] Wipe with clean dry towelette

[0126] Measure the delta E (cmc) which quantifies the colour evolution on the 2 types of stains

[0127] Clean with isopropanol.

[0128] Re-measure the delta E (cmc) after cleaning

[0129] if delta E (cmc)<2 excellent cleaning

[0130] if delta E (cmc)<5 good cleaning

[0131] if delta E (cmc) <7 average cleaning

[0132] if delta E (cmc) >7 poor cleaning

[0133] The composite membranes according to the invention have allowed obtaining results which qualify cleaning as “good”, whether for betadine or for eosin

[0134] Results of the Rests

TABLE-US-00001 Resistance Strength to of the Hold isopropanol Clean- assemblies of the Anti- (weight loss ability N/5 cm layer viral lower than of the (higher than after activity 5% after 2 h) stains 20N/5 cm) cleaning Silicone NOK OK Good OK Good comparative 100 daN/ membrane 5 cm Silicone >90% OK Good OK Good membrane 100 daN/ example 1 5 cm according to the invention PVDF NOK OK Good OK Good comparative  40 daN/ membrane 5 cm PVDF >90% OK Good OK Good membrane  38 daN/ example 2 5 cm according to the invention Silicone NOK OK Good OK Good comparative 150 daN/ membrane 5 cm Silicone >90% OK Good OK Good membrane 150 daN/ example 3 5 cm according to the invention

[0135] Where “OK” means that the test is deemed to be conclusive: the coated and varnished membrane according to the invention is compliant: cleanness has been validated.

[0136] In conclusion, it has been demonstrated that the composite membranes according to the invention have a resistance to cleaning with isopropanol, as well as an antiviral action, while preserving the desired properties of the corresponding comparative composite membranes.