POROUS MEDIA HAVING BIOCIDAL PROPERTIES

1 . A biocidal composition for the surface treatment of a porous substrate, comprising:

at least one hydrophilic binder,

at least one biocidal compound based on quaternary ammonium selected from non-polymeric quaternary ammonium salts of the following formula (CH 3 ) 2 A 2 N + X − , where:

A, which may be identical or different, represent linear C 6 to C 20 alkyl groups, and

X − is an anion selected from halide anions and sulfonate anions, and

at least one cationic sizing agent.

2 . The composition as claimed in claim 1 , comprising at least didecyldimethylammonium chloride (DDAC), dioctyldimethylammonium chloride or octyldecyldimethylammonium chloride.

3 . The composition as claimed in claim 1 , comprising at least one cationic sizing agent comprising at least one alkyl ketene dimer (AKD) and/or one styrene acrylate (SAE).

4 . (canceled)

5 . The composition as claimed in claim 1 , comprising at least one hydrophilic binder selected from polyvinyl alcohols, starches, latexes, hemicelluloses, carboxymethylcelluloses (CMCs), galactomannans, gelatins, polyurethane dispersions, and mixtures thereof.

6 . The composition as claimed in claim 1 , comprising from 1% to 50% by dry weight of hydrophilic binder(s) relative to the total weight thereof.

7 . The composition as claimed in claim 1 , comprising from 0.05% to 2.5% by dry weight of biocidal compound(s) based on quaternary ammonium relative to the total weight thereof.

8 . The composition as claimed in claim 1 , comprising from 0.08% to 1.5% by dry weight of cationic sizing agent(s) relative to the total weight thereof.

9 . The composition as claimed in claim 1 , further comprising at least one mineral filler.

10 . The composition as claimed in claim 1 , comprising from 0.1% to 5% by weight of filler(s), relative to the total weight thereof.

11 . The composition as claimed in claim 1 , further comprising one or more bacteriostatic, bactericidal, fungistatic, fungicidal, levuricidal or virucidal agent other than a biocidal compound based on quaternary ammonium.

12 . The composition as claimed in claim 1 , comprising water.

13 . A porous medium that has surface biocidal properties and has over all or part of at least one of its outer surfaces a surface treatment formed from a composition as claimed in claim 1 .

14 . The porous medium as claimed in claim 13 , having a Cobb value of not more than 50 g/m 2 measured with the Cobb test carried out according to standard ISO 535:2014 over a period of 60 s.

15 . The porous medium as claimed in claim 13 , said porous medium being fibrous.

16 . A process for producing a porous medium having surface biocidal properties as claimed in any of claim 13 comprising at least the steps of:

a) providing a porous substrate,

b) bringing all or part of at least one of the outer surfaces of said substrate into contact with a biocidal composition for the surface treatment of a porous substrate, comprising:

at least one hydrophilic binder,

at least one biocidal compound based on quaternary ammonium selected from non-polymeric quaternary ammonium salts of the following formula (CH 3 ) 2 A 2 N + X − , where:

A, which may be identical or different, represent linear C 6 to C 20 alkyl groups, and

X − is an anion selected from halide anions and sulfonate anions, and

At least on cationic sizing agent under conditions conducive to forming a deposit of said composition thereon,

c) drying said deposit so as to form said porous medium provided with biocidal properties.

17 . A method of conferring biocidal properties on a porous substrate or of boosting the hydrophobicity of a porous substrate, using a composition as claimed in claim 1 .

18 . (canceled)

19 . A method of producing a banknote or a security sheet or a paper for printing, writing or copying or of producing a packaging cardboard, or of producing papers, nonwoven materials, and textiles, writing and printing papers, coated papers, and copying papers, using a porous material as claimed in claim 13 .

20 . (canceled)

21 . (canceled)

22 . The composition as claimed in claim 1 , the cationic sizing agent being selected from alkenyl ketene dimers (AnKD), alkyl ketene dimers (AKD), styrene acrylates (SAE), rosins, alkenyl succinic anhydrides (ASA), and mixtures thereof.