FORMED ON A SURFACE FROM THE FILM FORMING COMPOSITION

TECHNICAL FIELD

[001] The present document relates to a disinfectant film-forming composition and the application thereof on a surface, forming a dry, disinfectant film on the surface.

BACKGROUND ART

[002] Contaminated surfaces in public areas contribute to the spread of microorganisms and viruses. Under certain conditions, microorganisms and viruses can survive several days on surfaces and objects such as handrails, lift buttons and door handles.

[003] Standard disinfection solutions used for cleaning of surfaces in public areas for killing or inactivation of microorganisms do not give a long-lasting effect. More long-term disinfectant treatments of surfaces may include special coatings, such as coatings comprising silver particles, and coatings comprising acrylate emulsion polymer and an organoalkoxysilane (US 5585407). Often such coatings are non-transparent and visible, and masks the underlying surface affecting the aesthetics of the surfaces. WO2011017097A1 discloses an anti-microbial coating that can be applied on a variety of surfaces by means of spraying. The composition forming the coating comprises water, anti-microbial agent and cationic rheology agent.

[004] Some requirements of anti-microbial coatings are that they should be abrasion resistant and be suitable to be used also in harsh environments without having to be continuously reapplied. Such coating is preferably bio-based, has a low adverse environmental impact, and is easily applied.

SUMMARY OF THE INVENTION

[005] It is an object of the present disclosure to provide an improved or at least an alternative disinfectant film-forming composition, which when applied on a surface forms a dry, disinfectant, lasting and abrasion-resistant film. The composition and film being bio-based and having a low adverse environmental impact. Further objects are to provide a method of preparing such a composition and a method of providing a dry, disinfectant film on a surface. [006] According to a first aspect there is provided a disinfectant film-forming composition comprising: a solvent comprising 90-100 vol.% of a non-aqueous solvent, which non-aqueous solvent has the following Hansen solubility parameters: a dispersion parameter of 15.30-17.56 MPal , a polarity parameter of 2.88-8.87 MPal , and a hydrogen bonding parameter of 5.48- 19.63 MPal ; a cellulose-based polymer dissolved in the solvent, and an anti-infective agent, wherein the amount of cellulose-based polymer dissolved in the solvent is 0.1% to 25% by weight based on the total weight of the film-forming composition, and the amount of the anti- infective agent is 0.25% to 2% by weight based on the total weight of the film-forming composition.

[007] The present disinfectant film-forming composition comprises simple bio-based materials, i.e. cellulose-based polymers, which for example are used in the cosmetics industry, combined with a disinfectant. Such film-forming composition has a low adverse environmental impact.

[008] When applied on a surface the film-forming composition forms a dry, disinfectant, lasting and abrasion- resistant film. The composition does not comprise any expensive components. The formed film is a fast-drying, transparent, invisible coating on several different types of surfaces (such as metal, wood, concrete, etc.).

[009] A dry film formed from the disinfectant film-forming composition on a surface (a surface such as of metal, mineral, natural or synthetic polymer, plastics, brick, tile, ceramic, porcelain, vinyl, glass, linoleum, wood or a fibrous material, such as textiles) is an effective sanitizer to remove pathogens, such as coronaviruses, from surfaces. The film-forming composition forms a dry, transparent, abrasion-resistant, long-lasting film on the surface. The film erodes in a controlled manner when the surface is touched, and a new surface is continuously created with disinfectant (biocide slow-release) until the film is gone.

[0010] The film needs to be mechanically robust to withstand multiple grabbing and rough use by people.

[0011] The solvent used in the composition comprises 90-100 vol.% of a non-aqueous solvent, or 93-100 vol.%, 95-100 vol.%, 97-100 vol.%, 99-100 vol. %, 90-99.9 vol.%, or 93-99.9 vol.%, 95-99.9 vol.%, 97-99.9 vol.%, 90-99.5 vol.%, 93-99.5 vol.%, 95-99.5 vol.%, 97-99.5 vol.%. [0012] The solvent may, apart from the non-aqueous solvent, comprise water. (If the solvent comprises 90 vol.% of a non-aqueous solvent, the rest, 10 vol.%, may be water.) Preferably, there is no or a very low amount of water present in the solvent. Water affects the solubility of the cellulose-based polymer, as the cellulose-based polymer is not water-soluble. The more water the solvent comprises, the more of the cellulose-based polymers added are not completely dissolved in the solvent, and there may be particles of undissolved material in the solvent, causing problems with clogging of the spray nozzle if the composition was to be sprayed on a surface. Further, water affects the time to form a dry film of the composition on a surface. With more water, the film is wet and sticky for a longer time, as compared to a composition comprising no or little water. If the solvent comprises too much water, it may be difficult to dissolve the cellulose-based polymer and achieve a good mixing of the disinfectant within the film. [0013] In this composition, the cellulose-based polymer is completely or close to completely dissolved in the solvent, which gives a visually transparent and colourless film (a light transmission of 90% or more) on a surface on which the film-forming composition is applied. [0014] The non-aqueous solvent used in the composition has the following Hansen solubility parameters: a dispersion parameter of 15.30-17.56 MPa% (1 PA=1 Kg/m*s ^A 2), a polarity parameter of 2.88-8.87 MPal , and a hydrogen bonding parameter of 5.4819.63 MPa%.

[0015] The Hansen Solubility Parameters (HSP) are a powerful tool to understand the issues of solubility, dispersion, diffusion and more. Solvents, polymers, nanoparticles, etc. can be well characterized by using three parameters: <5D for the dispersion (related to van de Waals forces), <5P for the polarity (related to dipole moment) and <5H for the hydrogen bonding. These three numbers capture the essence of the solubility behaviour of solutions, polymers, nanoparticles and other. They are rooted in thermodynamics; the sum of the squares of the <5Tot must equal the enthalpy of vaporisation of the solvent. STot is related to the cohesive energy - the energy required to break the solvent apart. In simple terms, if the heat of vaporization 5Tot1 required to extract of one molecule from the bulk is equal with the heat of condensation <5Tot2 then the net enthalpy loss is zero and mixing will happen.

[0016] The Hansen solubility parameters were obtained from data sets provided by the Hansen Solubility Parameters in Practice - HSPiP software (https://www. hansensolubility. com/HSPiP/).

[0017] Examples of non-aqueous solvents used in the composition and which fulfil the above stated Hansen solubility parameters are ethanol, isopropanol, 1 ,2-pentanediol, dipropylene glycol, 1 ,2-hexanediol, propylene glycol, tetraethylene glycol, methoxy methyl butanol, ethyl lactate, ethyl acetate, butyl-3-hydroxybutanoate, diethylene glycol monobutyl ether, triethylcCitrate, dipropylene glycol mono n-propyl ether, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, grape butyrate, 2,2-dimethyl-1 ,3-dioxolane-4- methanol, 1 -undecanol, tripropylene glycol monomethyl ether, propylene glycol monopropyl ether, dodecanol, 3-methoxy-3-methyl butanol, dimethyl adipate, dipropylene glycol monomethyl ether acetate, dimethyl succinate, propylene glycol monobutyl ether, dimethyl glutarate, dimethyl ethylsuccinate, 3-methoxy butyl acetate, n-propyl acetate, hexylene glycol diacetate, ethyl-3-ethoxy propionate, glycerol octanoate decanoate, 1 ,2-hexanediol, 1 ,2- hexanediol, or any mixture thereof.

[0018] The above listed non-aqueous solvents have the following Hansen solubility parameters, places in brackets after each solvent: ethanol (15.8;8.8;19.4), isopropanol_(16;6.8;17.4), 1 ,2-pentanediol (18.8;7.8;17.7), dipropylene glycol (16.5;10.6;17.7), 1 ,2-hexanediol (16.7;7.1 ; 17.5), propylene glycol ((16.4;6.1 ;8.9), tetraethylene glycol (16.7;9;14.6), methoxy methyl butanol (16;6.3;12.9), ethyl lactate (16;7.6;12.5), ethyl acetate (15.8;5.3;7.2), butyl-3-hydroxybutanoate (16.6;5.8;10.8), diethylene glycol monobutyl ether (16;7;10.6), triethylcCitrate (16.5;4,9; 12), dipropylene glycol mono n- propyl ether (15.6;6.1 ;11), polypropylene glycol (16.4;6.1 ;8.9), propylene glycol monomethyl ether acetate (15.6;5.6;9.8), propylene glycol monomethyl ether (15.6;6.3;11.6), grape butyrate (16.6;7.1 ; 12), 2,2-dimethyl-1 ,3-dioxolane-4-methanol (16.8;7.5;11), 1-undecanol (16.1 ;3.9;9.9), tripropylene glycol monomethyl ether (15.3;5.5;10.4), propylene glycol monopropyl ether (15.8;7;9.2), dodecanol (16;4;9.3), 3-methoxy-3-methyl butanol (16;6.3;12.9), dimethyl adipate (16.3;6.8;8.5), dipropylene glycol monomethyl ether acetate (16.3;4.9;8), dimethyl succinate (16.1 ;7.7;8.8), propylene glycol monobutyl ether (15.3;4.5;9.2), dimethyl glutarate (16.1 ;7.7;8.3), dimethyl ethylsuccinate (16.4;5.2;7.1), 3-methoxy butyl acetate (15.3;4.1 ;8.1 ), n- propyl acetate (15.3;4.3;7.6), hexylene glycol diacetate (15.3;4.5;7.2), ethyl-3-ethoxy propionate (15.9;5.8;6), glycerol octanoate decanoate (16.3;4.1 ;6), 1 ,2-hexanediol (16.7;7.1 ;17.5), 1 ,2-hexanediol_(16.7;7.1 ;17.5), or any mixture thereof.

[0019] A solvent such as toluene may be used, but is hazardous and therefore not of interest when the composition is to be applied on surfaces in public areas.

[0020] The amount of cellulose-based polymer dissolved in the solvent is 0.1 % to 25%, 0.5% to 25%, 1% to 25%, 5% to 25%, 10% to 25%, 15% to 25%, 20% to 25%, 0.1 % to 20%, 0.1% to 15%, 0.1 % to 10%, 0.1% to 5%, 0.1% to 1%, 1 % to 10%, 5% to 15%, or 10% to 25% by weight based on the total weight of the film-forming composition. In one embodiment the amount of polymer dissolved in the solvent is 0.1 % to 10%.

[0021] The amount of the anti-infective agent is 0.25% to 2%, 0.5% to 2%, 0.75% to 2%, 1% to 2%, 1.25% to 2%, 1.5% to 2%, 0.75% to 2%, 0.25% to 1.75%, 0.25% to 1.5%, 0.25% to 1.25%, 0.25% to 1 %, 0.25% to 0.75, 0.25% to 0.5%, 0.5% to 1%, or 1 % to 2% by weight based on the total weight of the film-forming composition.

[0022] As the composition is a simple composition without any reactive components or crosslinkers, the shelf life is long (years). There is no expected chemical reaction or chemical degradation of the composition. The shelf-life is mainly limited by the container in which the composition is stored and that this container can be tightly sealed.

[0023] The cellulose-based polymer may be selected from a group consisting of ethylcellulose, methylcelluose, nitrocellulose, cellulose acetate, hydroxypropyl cellulose, cellulose nitrate, guar gum, carboxylmethylcellulose, hydroxypropylmethylcellulose, and any combination thereof.

[0024] The cellulose-based polymer added to the solvent may be in powder form or in granules of micron to mm in size.

[0025] The cellulose-based polymer is not hydroxyethyl cellulose, which is a thickening agent and not a film-forming agent. [0026] The viscosity of the composition can be tuned by choosing cellulose-based polymers with different degrees of ethoxyl group substitution. If ethyl cellulose is used in the composition, a grade of ethoxy group substitution from 48-49.5 may be used (that is N grade). [0027] The composition comprises an anti-infective agent and for example ethanol as the solvent and it is, thereby, very unlikely for any mold of bacteria growth in the composition.

[0028] The anti-infective agent may be selected from cationic, anionic, non-ionic and zwitterionic surfactants.

[0029] Such surfactants are chemical compounds possessing both hydrophilic and hydrophobic groups. They are commonly found as active ingredients in household disinfectants and detergents.

[0030] Cationic surfactants may be quaternary ammonium compounds (QACs), such as benzyl (C8-C18) alkyl dimethyl ammonium chloride or benzalkonium chloride, alkyl trimethyl ammonium chloride, dialkyl dimethyl ammonium chloride, and didecyldimethyl ammonium chloride, didecyldimethyl, ammonium chloride, alkyl dimethyl benzyl, ammonium saccharinate, and cetyl pyridinium chloride.

[0031] Anionic surfactants may be sodium dodecyl sulfate, sodium laureth sulfate, n- lauroylsarcosine, and sodium linear alkylbenzene sulfonate.

[0032] Non-ionic surfactants may be nonoxynol-9 (nonylphenoxypolyethoxyethanol), Triton X- 100 (p-diisobutylphenoxy polyethoxyethanol), Brij-97(polyoxyethylene oleyl ether), Onyxol 345 (N,N-bis(2-hydroxyethyl)dodecanamide), Span-20, (sorbitan monolaurate), Span-80 (sorbitan monooleate), Tween-20 (polysorbate-20) and Tween-80 (polysorbate-80)

[0033] Zwitterionic surfactants may be Empigen BB®, an alkylbetaine based on a C12-C14 alcohol.

[0034] The anti-infective agent may be a cationic surfactant.

[0035] Cationic surfactants, such as chlorhexidine or quaternary ammonium compounds (QACs) are the best-known class of antimicrobial surfactant. In particular, QACs form the main bulk of cationic surfactants and inactivate microorganisms by solvating and disrupting lipid envelops and membranes. They are formed by a substituted cationic ammonium group (hydrophilic part), and a halide or sulfate anion (hydrophobic part). Examples are chlorhexidine, and QACs such as benzyl (C8-C18) alkyl dimethyl ammonium chloride (benzalkonium chloride), mono; bis (trimethylammonium methylene chloride)-alkyl (C9-15) toluene, and didecyldimethyl ammonium chloride, alkyl dimethyl benzyl, ammonium saccharinate, and cetyl pyridinium chloride.

[0036] A representative group of QACs is benzalkonium compounds or benzyl alkyl dimethyl ammonium compounds, which with a benzyl group connected to the ammonium group, become less soluble in water and readily soluble in other solvents such as ethanol and acetone. [0037] Another representative group of QACs is alkyl trimethyl ammonium compounds.

[0038] Another representative group of QACs is dialkyl dimethyl ammonium

[0039] The anti-infective agent may be a quaternary ammonium compound.

[0040] The quaternary ammonium compound may be a benzylkonium compound.

[0041] The benzylkonium compounds may be benzyl (C7-C18) alkyl dimethyl ammonium chloride, benzyl (C8-C18) alkyl dimethyl ammonium chloride, benzyl (C10-C16) alkyl dimethyl ammonium chloride, benzyl (C10-C21) alkyl dimethyl ammonium chloride, benzyl (tallow) alkyl dimethyl ammonium chloride, benzyl (coconut oil) alkyl dimethyl ammonium chloride and benzyl (soybean oil) alkyl dimethyl ammonium chloride.

[0042] The quaternary ammonium compound may be a combination of benzalkonium compounds, alkyl trimethyl ammonium compounds and/or dialkyl dimethyl ammonium compounds.

[0043] The dialkyl dimethyl ammonium compounds may be octyl decyl dimethyl ammonium chloride, didecyl dimethyl ammonium chloride and dioctyl dimethyl ammonium chloride. The alkyl trimethyl ammonium compounds may be tallow trimethyl ammonium chloride, octadecyl trimethyl ammonium chloride and palmityl trimethyl ammonium chloride.

[0044] According to a second aspect there is provided a method of forming a disinfectant filmforming composition, comprising: providing a solvent comprising 90-100 vol.% of a nonaqueous solvent, which non-aqueous solvent has the following Hansen solubility parameters: a dispersion parameter of 15.3-17.56 MPal , a polarity parameter of 2.88-8.87 MPal , and a hydrogen bonding parameter of 5.48-19.63 MPal ; dissolving in the solvent a cellulose-based polymer in an amount of 0.1% to 25% by weight based on the total weight of the film-forming composition, and adding to the solvent an anti-infective agent in an amount of 0.25% to 2% by weight based on the total weight of the film-forming composition.

[0045] The cellulose-based polymer may be dissolved in the solvent during stirring. No heating or only gentle heating of the solvent during the dissolution of the polymer is needed. The components are mixed/stirred until components are dissolved. The components may be added in the same beaker and there is no need to make two different solutions and thereafter mix such solutions. The formed composition is a single component composition containing biocide, not a multicomponent composition.

[0046] According to a third aspect there is provided a method of providing a dry, disinfectant film on a surface, comprising: providing a substrate with a surface to be coated with a dry, disinfectant film, applying the film-forming composition described above on the surface, allowing the film-forming composition to dry on the surface, thereby forming a dry, disinfectant film on the surface.

[0047] The composition can be applied on a surface, such as on a table surface, to provide a dry, disinfectant film on the surface. The surface may be a hard surface, a soft surface or anything there between. The surface may be of metals, minerals, natural and synthetic polymers, plastics, brick, tile, ceramic, porcelain, vinyl, glass, linoleum and wood. The surface may be of a fibrous material, such as textiles.

[0048] The composition can be applied on the surface by any means. The composition is applied on the surface to achieve a continuous and/or homogenous disinfectant film. Coating systems routinely used for paints and coatings, such as, but not limited to, brushes, rollers, paint pads, mats, sponges, combs, hand-operated pump dispensers, compressed air operated spray guns, airless spray guns, electric or electrostatic atomizers, backpack spray application equipment, aerosol spray cans, clothes, papers, feathers, styluses, knives, and other applicator tools can be used for applying the composition on a surface. The composition may also be applied by dipping of the surface/substrate into the film-forming composition. For fibrous substrates, such as textiles, the composition may be applied by exhaustion, foam, flex- nip, nip, pad, kiss-roll, beck, skein, winch, liquid injection, overflow flood, roll, brush, roller, spray, dipping, immersion, and the like. Preferably, the composition may be applied on surfaces during regular cleaning, requiring no special knowledge to apply it.

[0049] The film-forming composition forms a dry, transparent, invisible, abrasion-resistant, long-lasting film on the surface. The film erodes in a controlled manner when the surface is touched, and a new surface is continuously created with disinfectant (biocide slow-release) until the film is gone. The film further dries fast once applied on a surface, such as in 5 minutes. Based on the method of coating, coatings having a thickness of 0.1 to 1 microns may provide these qualities.

[0050] By wiping a surface having a formed dry disinfectant film thereon with an ethanol- soaked cloth, the film can be removed, if necessary. The film itself is very durable. How often the film needs to be reapplied on a surface depends on in how harsh an environment the film is arranged in. The formed film is ‘water-proof’ and does not wash off under rain or wet hands. [0051] The film forming composition may be applied on the surface by means of spraying. [0052] Spraying may here be an easy, hand-operated, non-pressurized spraying, in which the composition is put into an ordinary spray-bottle.

[0053] The consumer (e.g. restaurant/bar owners, hospitals, airline check-in counters, etc.) can apply this spray coating on e.g. their tables and other commonly touched surfaces. The product can also be used by consumers to spray on e.g. face-masks, in order to kill accumulated virus and reduce the risk of touching the masks.

[0054] As the composition can be sprayed on a surface using an easy, hand-operated, nonpressurized spraying it can be applied by untrained personnel by a simple and inexpensive method.

[0055] As the composition dries fast, evaporates, there are no problems with dripping when applying the composition on a surface. The composition will dry out before it drips. Due to the fast evaporation, multiple subsequent coatings may be applied on a surface if necessary for complete coverage of a surface. Thereby, any problem with inefficient surface coverage by non- homogeneous coating of surfaces can be overcome.

[0056] The spray/aerosol mist can be applied on almost any accessible solid or soft surface such as: wood, metal, plastic, textile, or glass, irrespective of shape. The applied drops may form a full film, patch like regions or a mixture of the two.

[0057] The disinfectant, dry film formed on a substrate surface, is robust and difficult to peel off with your fingers. The film appears smooth and is visually transparent, clear and colourless, such that the colours, and other visual features of the underlying substrate are still clearly visible through the film. The film is also weather and abrasion resistant and can withstand rough handling even with wet objects such as fingers.

[0058] An effective anti-infective action is obtained by the film as a portion of the anti-infective agent is always accessible at the surface. This depends on the solubility of the anti-infective agent in the polymer and the microstructure of the polymeric film. It is important to have a continuous exposure of anti-infective agent at the surface, even after progressive abrasions, until the film is completely removed. Unlike prior art (examples of slow-release systems), the anti-infective agent described here is locked in place with respect to the film and so even after some wear and tear the proportion of the exposed anti-infective agent stays the same as long as the film itself is present.

[0059] The dry, disinfectant film may be provided on a flat rigid surface.

[0060] The flat, rigid surface may be selected from a kitchen top, a table top, an office counter, and a tile.

[0061] The dry, disinfectant film may be provided on a non-flat surface.

[0062] The non-flat surface may be a surface of a wash-basin or a toilet bowl.

[0063] The surface may be a soft surface or comprise a soft surface section.

[0064] The soft surface or soft surface section may constitute or be part of a cushion or seat. [0065] The surface may be a porous surface or comprise a porous section.

[0066] The surface may constitute or be part of a filter.

[0067] Such filter may for example be an air filter.

[0068] The surface may be a surface of a metal rod.

[0069] The metal rod may be a handle-bar or a safety rail.

BRIEF DESCRIPTION OF THE DRAWINGS [0070] Fig. 1 shows viral infectivity reduction of a film composed of ethyl cellulose containing different amounts of benzalkonium chloride (BKC).

[0071] Fig. 2 shows log reduction results of an abrasion test performed on a surface provided with a coating comprising 1% BKC after 0, 20, 40 and 80 cycles, respectively.

[0072] Fig. 3 shows log reduction results of an abrasion test performed on a surface provided with a coating comprising 0.75% BKC after 0 and 80 cycles, respectively.

[0073] Fig. 4a and Fig. 4b show and compare the structure of the film when prepared with and without water in the formulation, respectively. The presence of water makes the film rough and globular, thereby making the film more opaque, compared to the smooth films obtained without water.

[0074] Fig. 5 shows a photograph comparing the two films as described in Fig. 4a and Fig. 4b. [0075] Fig. 6a and Fig. 6b. show a schematic of two films, with and without water in the formulation, respectively. In the case of the film formed with water in the formulation, the much larger surface area of interaction is likely causing a faster release of bioactive ingredient [0076] Fig. 7 compares release rate of the bioactive substance (BKC) from films prepared with and without water in the formulation. The release of the bioactive substance from films obtained with waterless formulation is much faster than from films obtained with formulation containing water.

DETAILED DESCRIPTION

[0077] Anti-microbial coatings should be abrasion resistant and be suitable to be used also in harsh environments without having to be continuously reapplied. Such a coating is preferably bio-based, has a low adverse environmental impact, and is easily applied. Below is described and exemplified a disinfectant film-forming composition and use thereof, which when applied on a surface, such as of metal, wood, concrete, etc., forms a dry, disinfectant, transparent, lasting and abrasion-resistant film. The composition and film being bio-based and having a low adverse environmental impact. The film erodes in a controlled manner when the surface is touched, and a new surface is continuously created with disinfectant (biocide slow-release) until the film is gone.

[0078] The disinfectant film-forming composition comprises a solvent comprising 90-100 vol.% of a non-aqueous solvent, such as for example ethanol or isopropanol, which non-aqueous solvent has the following Hansen solubility parameters: a dispersion parameter of 15.3-17.56 MPal , a polarity parameter of 2.88-8.87 MPal , and a hydrogen bonding parameter of 5.48- 19.635 MPa%. A cellulose-based polymer, such as ethylcellulose, methylcelluose, nitrocellulose, cellulose acetate, hydroxypropyl cellulose, cellulose nitrate, guar gum, carboxylmethylcellulose, hydroxypropylmethylcellulose, and any combination thereof, is dissolved in the solvent. The composition further comprises an anti-infective agent, such as a cationic surfactant (e.g. a quaternary ammonium compound (QACs) such as benzalkonium chloride).

[0079] The amount of cellulose-based polymer dissolved in the non-aqueous solvent is 0.1% to 25% by weight based on the total weight of the film-forming composition, and the amount of the anti-infective agent is 0.25% to 2% by weight based on the total weight of the film-forming composition.

[0080] The composition may be applied on a surface for example by means of spraying and allowed to dry, thereby forming a dry, disinfectant film on the surface.

[0081] Below is described a specific non-limiting example of the film forming composition and its use.

Experimental

Preparation of film forming composition

[0082] Ethyl cellulose (Ethoxyl content 48-49,5% Aquaion EC-N 10 Ashland) and a solvent comprising 99 vol.% ethyl acetate (the rest being water) were mixed together in a ratio of 5:95 wt.%, under magnetic stirring for a defined period of time (36 hours), forming a translucent, stable solution.

[0083] The anti-infective agent, benzalkonium chloride (BKC), was added to equal volumes of ethanol with dissolved ethyl cellulose, in an amount of 0%, 0.1%, 0.25%, 0.75% and 1% by weight, respectively, based on the total weight of the film-forming composition. The mixture was stirred for a defined period of time (1 hour), resulting in translucent, stable solutions.

Coating on surface

[0084] The formed compositions were fed to a commercial handheld spraying bottle. The compositions were sprayed onto different surfaces of aluminium sheets.

Film properties

[0085] After application on the surfaces, the compositions quickly vanished and the obtained films became non-sticky, soft and dry in a certain amount of time (30 minutes). The films were visually clear/transparent.

Mechanical abrasion

[0086] Mechanical abrasion tests were performed on surfaces provided with the abovedescribed coating. Such mechanical abrasion tests are performed by Elcometer 1720 abrasion and washability tester.

[0087] The coated films were loaded into the instrument and abrasion was performed using a household microfiber cloth against the coating, under 450 g load. The choice of 450 g load, comes from several Standard test protocols for evaluation of such coatings (e.g. EN 14460) and it loosely reflects the average load applied by a person pressing down on the surface with a few fingers.

[0088] The coatings were evaluated after 20, 40, and 80 cycles of abrasion. After visual evaluation of the coating integrity, the samples were evaluated for viral infectivity (reduction). [0089] Viral infectivity reduction tests were carried out by placing a drop of virus inoculum (SARS-COV-2, D614G aa strain) for 30 minutes, followed by diluting (series of 10 fold dilutions) the inoculum into living cell-cultures (Kidney epithelial cells, Verket Monkey). Based on the number of infected living cells, compared to the reference sample which was not exposed to the anti-viral coating, the viral infectivity reduction caused by the coating was estimated and reported in terms of log reduction. Typically coatings that shows log reduction of greater than 3 (99.9% reduction) is said to be effective.

[0090] In Fig. 2 is shown the log reduction results of an abrasion test performed on a surface provided with a coating comprising 1% BKC after 0, 20, 40 and 80 cycles, respectively.

As can be seen, the log reduction after 20, 30 and 80 cycles were substantially the same, (compared to 0 cycles). This indicates that at least 99.9% of the viruses are neutralized by the as made coating and this improved to 99.99% infectivity reduction after abrasion. Thus the coating effectiveness remains undiminished, in fact improved after abrasion.

[0091] In Fig. 3 is shown the log reduction results of an abrasion test performed on a surface provided with a coating comprising 0.75% BKC and prepared with ethanol as solvent instead of ethyl acetate. The film prepared from this formulation was mechanically worn out with 0 and 80 cycles, respectively. We obtain 99.99% reduction in infectivity on as prepared coatings, which is undiminished even after 80 cycles of abrasion. With this test we can conclude that even with a slightly lower fraction of BKC, and using ethanol as a solvent, the formulation is effective in suppressing viral infectivity.

[0092] We also performed some trails with 10 volunteers, who were given coated samples and over the course of a calendar month, daily rubbed against the coating with their bare fingers. This reflected different situations of finger wetness, sweat-levels and other practical variables associated with human skin. We observed no instance of skin irritation from any of the volunteers and the coatings remained intact in all cases, except for some minor peeling along the edges.

[0093]

Viral infectivity reduction

[0094] In Fig. 1 is shown viral infectivity reduction of a film composed of ethyl cellulose containing different amounts of benzalkonium chloride, 0%, 0.1%, 0.25%, 0.75% and 1%, as described above. From Fig. 1 it is shown that already at 0.75% BKC, there is a very strong effect of virus removal i.e. more than 99.9%.

BKC release study: Film preparation: Solution preparation:

[0095] The first solution was prepared by adding 5wt% EC - Ethyl Cellulose (Prod Nr. 200646 Ethoxyl content 48-49,5% Sigma Aldrich) in Ethanol (99.5 vol%) followed by the addition of 2wt% BKC and mixed using a magnetic stirrer for 24 hours;

[0096] The second solution was prepared by adding 5 wt.% EC - Ethyl Cellulose (Prod Nr. 200646 Ethoxyl content 48-49,5% Sigma Aldrich ) in Ethanol (99.5 vol%) followed by the addition of 2 wt% BKC and mixed using a magnetic stirrer for 24 hours. After that 11 wt.% water was added and mixed under magnetic stirrer for 2 additional hours.

[0097] The two solutions were coated on separate Al foils (100 cm ² ) using a 120 micron rod coater to ensure film uniformity. The drying time for the first solution was 2-3 minutes while for the second one it was 5-7 minutes. Both films adhered well and uniformly on the Al surface. The second sample containing 11 wt.% water had a white haze (visibly less transparent) as compared to the first sample without water.

UV Vis release study.

[0098] The two Al foils were placed in a closed environment and 10 mL water was placed on each sample covering a film area of about 60 cm ² . To minimize the water loss through evaporation extra water was placed outside the sample area. At predefined time intervals about 1.5 mL of the water was extracted from each sample and the UV Vis spectra in the in the wavelength range of 180 nm - 400 nm was recorded and used to determine the concentration of BKC that has been released into the water over time (25 hours). An UV Vis calibration curve for BKC with different concentrations of BKC in water was determined prior to running the experiments.

Discussion

[0099] Non-aqueous solvents (solvents comprising 90-100 vol.% of a non-aqueous solvent) are used in the disinfectant film-forming composition . When compared to test coatings prepared from water solutions of polymers, the non-aqueous solvents allowed films to dry out and form abrasion resistant coatings within minutes, compared to over an hour needed for water-based coatings. Here the cellulose-based polymer was chosen as a safe and bio-based material with low environmental impact, which allowed good mixing with the active anti- infective ingredient (e.g. BKC). Any other similar polymer that mixes well with similar active materials could be used, as long as it can be dissolved in a preferred non-aqueous solvent. When using a lower proportion of the non-aqueous solvent, the solution will be viscous and the resulting coating a thicker coating. Conversely, when using a higher proportion of the solvent, the resulting coatings will be thinner.

[00100] The viral infectivity action occurs at the very top layer of the formed coating regardless of the coating thickness, so the anti-viral function of the coating would be the same. The physical attributes of the coating, such as abrasion resistance, may be improved with thicker coatings. There is a lower limit of the proportion of the active ingredient (e.g. BKC) to obtain a reasonable viral infectivity reduction (log 3, which is 99.9% reduction). Increasing the proportion beyond that minimum threshold would certainly improve the effectiveness, but could also cause skin irritation for some individuals. An optimum balance depends of the exact needs of the situation where these coatings are to be applied.

[00101] Additional BKC release experiments were performed to demonstrate that water addition to the formulation results in a rough or globular, opaque film that can release the BKC much faster as compared to the formulation where no water is added. Indeed, as represented in Fig 4a, after applying the disinfectant coating formulation to the surface, the non-aqueous solvent evaporates first and the solubility of the polymer in the remaining solvent mixture drops result in a rough or globular film that can scatter light in all directions. On the other hand, if the formulation is waterless, then during the evaporation of the non-aqueous solvent a more uniform and transparent film is formed that allows light to pass (Fig. 4b). To demonstrate that, Fig. 5 shows a photograph of a disinfectant film coated on a transparent glass substrate. The film coated on the upper substrate in the photograph contained 11 wt.% water and the film coated on the lower substrate in the photograph contained no water.

[00102] When in contact with water, as represented in Figs 6a and 6b, the two films will have a very different contact area. A rough or globular film will have a higher contact area with water (Fig. 6a) as compared to a uniform film (Fig. 6b). An active ingredient imbedded in such a rough or globular film, here BKC, will be released much faster, resulting in depletion of the anti-viral effect in a shorter period of time, compared to a smooth film formed with little or no water in the formulation.

[00103] To demonstrate the fact that BKC can be released in a controlled manner over a very long period of time from a clear and uniform film, we have produced two formulations of EC, BKC and Ethanol as described in the experimental section: one without water and one with 11 w.t% water. These films were exposed to water and the release of BKC was measured using UV Vis method over 25 hours. As observed in Fig. 7 the release profile of BKC is dependent on the film structure. The concentration of BKC released from the transparent film resulted from a formulation without water shows an initial release over about 2-3 hours then it shows a monotonous increase almost flattening out after 25 hours. On the other hand, the concentration of BKC released from the opaque film resulted from a formulation with 11 wt.% water show a much higher initial release followed by a more abrupt/unpredictable release within the 25 hour measurement.

[00104] A film-forming composition comprising large amounts of water and some water- soluble co-polymers results in globular and soft films that are comfortable when for example directly applied on the skin. This is needed in many applications, including wound-healing, surgical site disinfections, skin-patches etc. The disinfectant film forming composition described above is intended to be a tough film that cannot be removed by gentle touches or water splashes. It is intended to give a continuous disinfectant protection for a long duration of time (many days or weeks).

[00105] A common strategy to improve mechanical robustness of film-forming compositions is to introduce a chemical or physical cross-linking effect. This complicates the formulation, including affecting the ‘shelf-life’ of such products and also imposes restrictions on the methods of application or drying of the film. Such cross-linkers also add to the eventual cost of such products. The present composition is a simpler solution, wherein a wide range of solvents with a low water content (< 10%), and chosen according to the target substrate and/or other considerations, will produce a tough and long-lasting coating on a wide range of substrates without the need of such cross-linkers and/or complicated application and drying methods.

[00106] The non-aqueous solvents ethanol, ethyl acetate and toluene (and mixtures of any of these) were able to solubilize the cellulose-based polymers listed above. Using the HSP program (Hansen Solubility Parameters in Practice - HSPiP software (https://www. hansensolubility. com/HSPiP/)) boundaries of the polymer solubility were obtained (a dispersion parameter, 5D, of 15.30 - 17.56 MPal , a polarity parameter, 5P, of 2.88 - 8.87 MPal , and a hydrogen bonding parameter, 5H, of 5.48 - 19.63 MPal ). All the non-aqueous solvents listed in above are within these boundaries and will therefore solubilize the polymer in the same manner as ethanol, ethyl acetate and toluene, either individually or as a mixture.

[00107] Based on the Hansen solubility parameters concept, simply put that “like dissolve like”, all cellulose-based polymers listed above are considered to behave in a similar way to ethyl cellulose (used in the experimental section above) with respect dissolution in nonaqueous solvents.

[00108] Anti-infective agents are usually fairly small molecules, such as surfactants (ionic, nonionic and zwitterionic) and quaternary ammonium compounds, which could be easily imbedded or formulated in a solid polymeric film matrix. As their solubility in the polymeric films is always nonzero, and due to film cracking or wear, they will start to leach out. The mechanism for pathogen killing is generally based on membrane disruption for which the polarity and the size of the molecule is an important parameter. Provided with the fact that the anti-infective agents discussed above have a somewhat similar size and polarity, it is expected that they will give similar results as are shown for BKC above.

[00109] Our data shows that the lower limit for BKC to have an anti-bacterial effect is 0.25 wt% or more, which is most likely to be the same for all anti-infective ingredients listed above (due to size and molecular speciation related leaching). However, due to the possibility of skin irritation with a very high content of the anti-infective agent, such as BKC, it is desirable that amount of anti-infective agent is limited, aiming to have most effect with minimum use of anti-infective agent.

[00110] In eth experimental section, a formulation comprising 5% by weight of cellulose- based polymer (Ethyl Cellulose) dissolved in a non-aqueous solvent was used. A lower amount of the polymer, i.e. down to 0.1 % by weight, will also work in a similar manner since a reduction in polymer composition may be compensated by a thicker application layer or higher amount of anti-infective agent in the formulation. Generally for obtaining very fine films on surfaces (especially non-flat and maybe porous surfaces), a lower concentration of the polymer in the formulation may be desired. The upper limit of the polymer amount in the composition may be as high as 25% by weight, as long as suitable non-aqueous solvents are found that allow the dissolution of the high amount of polymer. The target viscosity would also be a parameter determining the polymer concentration. Different film application methods have different target viscosities for the formulation.