BE1029958B1 - IMPROVED BIOCIDAL COATING - Google Patents

Abstract

A process for obtaining a siloxane coating comprising a biocidal quaternary ammonium, one or more crosslinking agents and optionally an agent for adhesion to a substrate, the corresponding coating and its uses, as well as the substrates covered with this coating.

Description

azz BE2021/5916

IMPROVED BIOCIDAL COATING

Technical area

The present invention relates to a process for obtaining an improved biocidal and virucidal coating.

Prior art

A coating created from epoxy resin, corresponding to a thermosetting liquid polymer is known. When the epoxy resin is cured, often in the presence of a catalyst, it can be shaped to suit the needs of the user. For example, it can be smoothed, cut or perforated. It works in liquid form and is applicable in many areas such as jewelry, furniture or even flooring.

Unfortunately, this resin has the disadvantage of requiring several days of drying to be hardened and the hardness depends on the temperature or the time of treatment or the presence of catalysts. Another disadvantage of this resin lies in the fact that it degrades over time.

For example, patent US8158191 discloses a two-step process: a first layer of polyurethane is applied to a surface of a polycarbonate or polyamide substrate, then an abrasion-resistant silane-type coating is applied to the first layer of polyurethane. .

US4345053 discloses a moisture-curable sealant composition for application to non-porous substrates. The sealing composition comprises a silicon-terminated polymer which is obtained by reaction between a polyurethane, polyether or polyethylene prepolymer carrying two OH (or amine) functions with a polyisocyanate. When the polyisocyanate is no longer detectable, an organosilane bearing an isocyanate group is then added. The process is therefore carried out in several stages.

Patent EP2785801 discloses a process for obtaining a hardenable film-forming composition applied to the substrate to attenuate the accumulation of ice on the substrate. This composition consists of two layers that are applied one after the other.

Patent EP3209739 discloses a composition for obtaining a two-component coating. The coating, as a product, does not contain isocyanate which has not reacted during the production process, which is an essential characteristic of this document. Unreacted isocyanates are removed from the mixture by an additional step. The crosslinking is done via epoxy or acrylate functions.

Thus, the methods of the prior art are carried out in two stages, each being well controlled.

Quaternary ammoniums coupled to an aliphatic chain have been used as a bactericidal or even virucidal agent for the development of antibacterial or antiviral coatings, in particular those in the form of an organosilane, such as 3-(trinydroxysilyl) propyldimethyloctadecyl-ammonium chloride. Indeed, several scientific studies show that quaternary ammoniums prevent the growth of bacteria and certain viruses on solid supports.

EP1863865 discloses a process for the preparation of a quaternary ammonium antibacterial agent containing silica combined with other polymers.

Document EP2285857 presents an antibacterial coating in the form of an interconnected polyurethane-silica network with quaternary ammoniums used as an antibacterial agent.

The process is carried out in two stages, the first stage consists in preparing a polyurethane functionalized by a siloxane function and a second stage where the siloxane functions carried by the polyurethane react with the siloxanes carrying quaternary ammoniums at temperatures between room temperature and 100°C. The advantage of a two-step process is that there is good control of the various reactions, that any excess reagents can be neutralized. Also, catalysts or other compounds that are not desired in the coating are easily removed.

However, the reactions between the siloxane functions are not very rapid at room temperature and require an additional baking step at a temperature above 100° C. to ensure the chemical bonds between the quaternary ammonium and the polyurethane network. Another disadvantage of this type of coating is that once applied to a solid support, it has a limitation in terms of mechanical resistance when subjected to external stresses.

Brief summary of the invention

The present invention aims to solve the drawbacks of the state of the art, in particular to provide a process for obtaining a coating which is easy, rapid and economical, the coating being biocidal and virucidal and having reinforced mechanical resistance.

Thus, A first object of the present invention consists of a process for obtaining a transparent and biocidal coating in which: - a cyclic organic molecule is mixed comprising at least two silane functions hydrolysable into two silanol groups and dimethyloctadecyl(3 -[trimethoxysilyl)propyl) ammonium (or any other molecule having a biocidal function and an equivalent structure, but whose hydrocarbon chain comprises a carbon number other than 18, for example 8, 9, 10, 11, 12, 13, 14 , 15, 16, 17) in an aqueous solution or a water/water-soluble organic solvent mixture, - this mixture is acidified and left to gel, - this gelled mixture is applied to a substrate under conditions allowing crosslinking silanol groups formed.

Advantageously, the substrate is glass, a metal surface (non-ferrous or ferrous, including steel), plastic.

A related aspect of the present invention relates to the coating obtainable by the above process.

Alternatively, this related aspect of the present invention relates to a coating of a surface which is transparent, bactericidal and virucidal comprising at least 20% by mass of dimethyloctadecyl ({3- (trimethoxysilyl) propyl) ammonium (or any other molecule having a biocidal function and an equivalent structure, but whose hydrocarbon chain comprises a carbon number other than 18, for example 8, 9, 10, 11, 12, 13, 14, 15, 16, 17) and at least 25% by mass of a crosslinking agent being a cyclic organic molecule comprising at least two silane functions which can be hydrolyzed into two silanol groups, said silanol groups having formed a siloxane network with the silyl functions of said dimethyloctadecyl(3-(trmethoxysilyl)propyl)ammonium molecule.

Another aspect of the present invention relates to the virucidal use of this coating. Another aspect of the present invention relates to a glass or a plastic covered by this coating.

Detailed description of an embodiment of the invention

The inventors noticed, surprisingly, that the addition of a molecule having bactericidal and virucidal properties to a coating of the siloxane type could see this effect reinforced (especially the virucidal effect) if this molecule is added in large quantity, and/or is added in synergy with an adjuvant polymer. However, adding this molecule in large quantities is difficult because the physical properties of the coating (transparency, adhesion, scratch resistance, mechanical strength) must be preserved, in particular for a coating to be applied to glass: the high concentrations may result in clumping or precipitation, or an unacceptable coating. On the other hand, the addition of adjuvant molecules is done by diluting the active molecules (biocides or allowing mechanical resistance): it is therefore a counter-intuitive use.

A first object of the present invention consists of a process for obtaining a coating in which: - a cyclic organic molecule is mixed comprising at least two silane functions which can be hydrolyzed into two silanol groups ('crosslinking agent') and dimethyloctadecyl (3-(trimethoxysilyl) propyl) ammonium ('quaternary amine' and/or biocidal molecule; or any other molecule having a biocidal function and an equivalent structure, but whose hydrocarbon chain comprises a carbon number other than 18, for example 8 , 9, 10, 11, 12, 13, 14, 15, 16, 17) in an aqueous solution or a water/water-soluble organic solvent mixture, - this mixture is acidified and allowed to gel, - this mixture gelled on a substrate under conditions allowing the crosslinking of the silanol groups formed.

The inventors have noticed that this multifunctional (di- or trifunctional) cyclic organic crosslinking agent provides rigidity to the final product and allows correct crosslinking.

In the context of the present invention, the terminology "hydrolyzable silane functions in silanol group" preferably means that an Si atom is derived from 1, 2, or, preferably 3, hydrolyzable groups, such as alkoxy groups. . Methoxy or ethoxy groups are preferred. During the steps of the process, at least one of these groups will be hydrolyzed (in an acid medium), so as to release an alcohol and to generate functional groups.

Si-OH (silanol), which can then be cross-linked to each other, so as to create a siloxane network. In the part of the invention relating to the coating, this terminology is sometimes retained and signifies the origin of the product, but also includes any alkoxy functions which have not been hydrolyzed. The terminology “silyl” is also used, to designate the molecule, whether it is original — (alkoxy-silane) or hydrolyzed into silanol.

Controlled acidification and the choice of water concentration allow crosslinking kinetics that are neither too fast nor too slow.

Too rapid cross-linking resulting in inhomogeneities in the gel and/or precipitation, which is detrimental. A properly formed gel can be easily applied and will be transformed into a coating with the required qualities.

Preferably the quaternary ammonium (biocidal molecule) is added via a composition and this quaternary ammonium is substantially pure, for example at a concentration of at least 40% (weight of the quaternary ammonium: total weight of the composition including the solvent ), at least 50% (by weight), at least 60% (by weight), or even at least 70% (by weight); alternatively, without counting the solvent, the quaternary ammonium is at least 80% pure (quaternary ammonium weight:dry weight of the composition), at least 83%, ideally even purer. This means that there are only a few 'dry' contaminants in the composition comprising the quaternary ammonium. Among these 'dry' contaminants is (3-chloropropyl)trimethoxysilane: a molecule which has the ability to insert itself into the siloxane network, but which will not confer bactericidal or virucidal properties. Thus, dimethyloctadecyl(3-(trimethoxysilyl)propyl)ammonium benefits from being as pure as possible; this also applies to compositions comprising any other molecule having a biocidal function and an equivalent structure, but whose hydrocarbon chain comprises a carbon number other than 18, for example 8, 9, 10, 11, 12, 13, 14 , 15, 16, 17.

By “virucidal activity”, in the context of the present invention, is preferably meant the ability of the coating or one of its constituents to significantly reduce the quantity of virus which would be placed therein, in particular of viruses enveloped in a membrane. Preferably the reduction is at least 80%, preferably at least 85%, at least 90%, at least 95%, even 99% or more, this preferably for a measurement time of between 30 minutes and 5 hours , advantageously after approximately 3 hours of measurement. The viruses (enveloped in a membrane) placed on the coating according to the invention are thus neutralized due to the interaction of the coating or of one of its constituents with its membrane, which makes them non-infectious (even if they can still be recognized by the immune system, which is, in practice, advantageous: in addition to passive immunization of populations, such deactivated viruses could be harvested from the surfaces according to the invention and administered to patients, in particular in countries where it is difficult to administer vaccines that must be stored at very low temperatures).

Preferably, the mixture further comprises an (adhesion) molecule comprising a function that can be hydrolyzed into a silanol group and a function allowing adhesion to the substrate, the method further comprising the step of fixing the gelled mixture (further comprising this adhesion molecule) on the substrate by a physical means, such as a baking step (eg at 100° C.-170° C., for example around 150° C.) or UV treatment, or else by reaction chemical with the substrate or with any primer coat that may have been deposited on the substrate.

The addition of this adhesion molecule dilutes the concentration of crosslinking agent and quaternary amine, so its concentration must be well adapted. Ideally no more than about 20% by weight (weight of this adhesion molecule:weight of the dry constituents of the composition), thus a preferred value range is from 5% to about 20% by weight.

Among the preferred adhesion molecules, there are molecules having at least (1) a silane function hydrolysable to silanol and (ii) an epoxy, acrylate, methacrylate group or an organic group having a reactive carbonate, such as molecules having a cyclic (nonaromatic) with 5 or 6 carbons, this cycle being derivatized by a carbonate group, the group (ii) can advantageously react with the thiol or with the amine of the primary layer if it is present, or directly with the substrate, for example if the group (ii) is an acrylate derivatized by a (tetra hydro)furan and the substrate is the plastic (by means of UV radiation).

In the context of the present invention, the term "dry constituents" preferably includes all of the molecules inserted into the mixture, with the exception of solvents such as water and alcohols (eg isopropanol, but also ethanol, methanol, or even other organic solvents used). The dry constituents therefore include at least the crosslinking agent and dimethyloctadecyl(3-(trimethoxysilyl)propyl]ammonium (and/or any other molecule having a biocidal function and an equivalent structure, but whose hydrocarbon chain comprises another number of carbon than 18, e.g. (3-chloropropyl)trimethoxysilane, any adhesion molecules, or even the polymer (adjuvant) derivatized at the two ends, each by a silane group which can be hydrolyzed to silanol (see below).

Advantageously, the 'dry constituents' essentially consist of all the molecules inserted into the mixture (described above in this paragraph), with the exception of the solvents.

Preferably, more than 20% (by weight), more than 25% (by weight), more than 35% (by weight) of (the crosslinking agent) the cyclic organic molecule comprising at least two hydrolyzable silane functions in two silanol groups are added to the mixture. The percentage is by weight: weight of this cyclic organic molecule comprising at least two silane functions which can be hydrolyzed into two siianol groups, relative to the weight of the sum of the dry constituents as described above.

Such a percentage ensures the rigidity of the coating, its scratch resistance, and good cross-linking. This percentage may be reduced somewhat (eg 20 or 25%) when the polymer (adjuvant) derivatized at both ends is added (see below).

Preferably, more than 20%, preferably more than 25%, 30%, 35% such as about 40% of (quaternary ammonium biocidal) dimethyloctadecyl (3- (trimethoxysilyl) propyl) ammonium is added to the composition. It is a percentage by weight:weight of dimethyloctadecyl(3-(trimethoxysilyl)propyl)ammonium, relative to the weight of the sum of the dry constituents, as described above.

Such a percentage of quaternary amine ensures a good bacteriocidal and even virucidal effect.

Preferably, this method comprises the step of adding to the mixture a polymer (adjuvant polymer) comprising at each of its two ends a terminal silane function hydrolyzable as a silanol group (therefore in all two terminal silane/silanol functions).

Preferably, this polymer is a copolymer having segments of different stiffness.

Preferably, this (co-)polymer is chosen from polyester, polyether, polyurethane, polycarbonate and polyacrylate, or even a mixture of two (two polyesters, or a polyester and one of the other polymers, a polyether and one of the other polymers, a polyurethane and one of the other polymers, a polycarbonate and one of the other polymers).

Preferably, this (co-)polymer (adjuvant) has a mass of between 500 and 2200 Da (i.e. 300 to 2000 Da of polymer without counting the silane-alkoxy functions), preferably between 700 and 1700 Da (i.e. 500 to 1500 Da of polymer without counting the silane-alkoxy functions) or between 700 and 1200 Da (i.e. 500 to 1000 Da of polymer without counting the silane-alkoxy functions).

Typically, this (co-)polymer (adjuvant) is added at a content of between 5 and 25% by weight: weight of the (co-)polymer, weight of all the dry constituents of the mixture, preferably between 7 and 20 % by weight, more preferably between 10 and 15% by weight.

When this (co-)polymer (adjuvant) is added, the content of crosslinking agent can be reduced, for example to a content of 25% by weight, or 30% by weight (weight of crosslinking agent: weight of the sum of the dry constituents). This maintains the high biocidal quaternary amine content. Alternatively, it may even be somewhat reduced, given the excellent results obtained by the inventors.

The inventors noted, to their surprise, that this particular (co-)polymer (adjuvant) allowed more quaternary ammonium (biocide) functions to be exposed to the surface of the coating, which retained its mechanical properties. Thus, even if the addition of this polymer is made to the detriment of the crosslinking agent, the coating retains its advantageous physical properties and the final biocidal effect, in particular virucidal effect, is advantageously increased.

The inventors have noted a more advantageous effect when the polymer is, in practice, a copolymer (eg composed of two different polyesters) and/OR a structure having a more rigid segment and a less rigid segment. According to the expertise of the inventors, the more rigid segments provide mechanical strength, while the less rigid segments (certain polyesters, or oligoethers) provide better impact resistance.

Preferably, in this process, the mixture is acidified to a pH between 2.5 and 5.0, advantageously between 3 and 4 (3.0 and 4.0). This

DH binds advantageously by the addition of a medium-strength acid (see below).

Preferably, when the invention is put into practice on a small scale, the mixture resulting from this process is applied to the substrate by centrifugation (spin coating): application in one or more places on the substrate, then centrifugation in such a way to evenly cover the substrate. Other methods that can be applied on a larger scale are spraying, dip coating, flow coating or the roll to roll procedure.

Advantageously, the substrate is glass, a metal surface (non-ferrous or ferrous, including steel) or plastic.

Preferably, the substrate is glass, which represents a particular difficulty since the transparency of the coating must be ensured everywhere.

Advantageously, when the substrate is glass, the method comprises the preliminary step of applying a primer layer to the glass, the primer layer consisting (essentially) of a siloxane network comprising primary amines or these thiol functions; in addition the (adhesion) molecule comprising a function that can be hydrolyzed into a silanol group and a function allowing adhesion to the substrate is present: this function allowing adhesion to the substrate (to the primer layer) is preferably an epoxide, of preferably the 3-

Glycidyloxypropyl)trimethoxysilane; CAS 2530-83-8), this method preferably comprising a final stage of baking on the substrate at a temperature above 100° C. (eg at around 150° C.). High temperature greatly accelerates further crosslinking

(already started during the formation of the gel); however the inventors have noticed that a higher temperature, e.g. higher than 170°C is very problematic, even when the substrate is glass.

Alternatively, the (adhesion) molecule comprising a function that can be hydrolyzed into a silanol group comprises, as function allowing adhesion to the substrate (to the primer layer), an acrylate or a methacrylate.

Preferably, the adhesion molecule is incorporated at a content of between 10 and 30% by weight: weight of the adhesion molecule: dry weight of the mixture, preferably between 15 and 20% by weight. Since this adhesion molecule is added to the detriment of the crosslinking agent and of the bifunctional polymer (adjuvant) (if present), or even of the biocidal quaternary ammonium, its presence somehow dilutes the active principles, so that the lowest content which ensures good attachment to the substrate is preferred.

Thus, the epoxide or acrylate groups will react with the amines or thiols of the primer layer, which ensures good attachment of the coating to its substrate (the glass). This also works when the substrate is the metal (same primer layer comprising a primary amine or a thiol, adhesion molecule comprising a (meth)acrylate).

Advantageously, when a primer layer comprising a primary amine or a thiol is applied (eg on glass or metal) and the coating comprises an acnlate, a phosphine type catalyst is added during the baking step.

Another advantageous substrate is plastic, preferably plastics which resist temperatures of 100° C. or even higher. Indeed, many surfaces potentially contaminated by pathogens are made of plastic (door handles, everyday objects, shopping carts, support systems in public transport, public seats, kitchen utensils, surfaces in communities, etc.) : the inventors have understood that the covering of these surfaces with the biocidal coating of the present invention would solve a major problem, which goes beyond the management of Covid-19.

Preferably, when the substrate is plastic, the method comprises the step of adding to the reaction mixture an adhesion molecule being an acrylate (and/or a methacrylate), for example an a (meth)acrylate comprising one or more hydrolyzable functions into a silanol group and (a (meth}acrylate) comprising one or more (tetrahydro)furan function(s) (ideally the same molecule carries both functions); the method further comprising the step of fixing the mixture to the substrate by baking (at a temperature compatible with the plastics), or by applying ultraviolet radiation, preferably before applying the conditions allowing the crosslinking of the silanol groups formed (e.g. baking at a temperature compatible with the plastic, such as at a temperature of approximately 100° C.), or during conditions allowing the crosslinking of the silanol groups formed (eg slower crosslinking at a temperature below 100° C.).

Preferably, the adhesion molecule (acrylate) is incorporated at a content of between 10 and 40% by weight: weight of the adhesion molecule: dry weight of the mixture, preferably between 15 and 20% by weight. GIVEN that this molecule is added to the detriment of the crosslinking agent, or even of the biocidal quaternary ammonium, its presence somehow dilute the active ingredients, so that the lowest content which ensures good attachment to the substrate is preferred . On the other hand, in the case where the acrylate and/or methacrylate (adhesion molecule) is the adjuvant polymer (eg a copolymer comprising two silane functions hydrolysable to silanol, one at each end and the function

(tetranydro)furan, one of the constituents of the copolymer being of the acrylate type), this acrylate copolymer can be incorporated in larger quantities, since its dilutive effect is nuanced, since it replaces the adhesion copolymer, the adjuvant polymer and the adhesion molecule being the same entity.

Preferably, the cyclic organic molecule (crosslinking agent) comprising at least two silane functions which can be hydrolyzed into two silanol groups consists (is) of a planar organic ring, preferably the ring consists solely of carbon and nitrogen atoms, these (at least 2) carbon and/or nitrogen atoms being derivatized by an alkoxysilyl group, preferably said molecule is Tris[3-(trimethoxysilyl)propyl]isocyanurate; CAS 26115-70-8, or 1,4-Bis(trimethylsilyl)benzene; CAS 13183-70-5. Preferably, the silane group is not part of the cycle and is grafted onto one of the atoms (C or N) constituting the cycle.

In this method, preferably, the solvent is a water:alcohol mixture (a water-soluble alcohol), preferably water:sopropanol, preferably in a mass ratio of between 1:1 and 1:5, such as about 1:2.

The inventors have noticed that the addition of an alcohol slows down the hydrolysis of the silane groups into silanol. Alcohols are preferred over other organic solvents that do not have a hydroxyl function. Preferred alcohols are short chain, and/or water soluble. Methanol, ethanol, propanol isomers, and mixtures thereof are preferred.

Preferably, the acid is of medium strength (1<pKa<4; preferably 1<pKa<2) and is added at a maximum content of 5% by weight of the acid (weight of the acid: weight dry constituents), so as to obtain the acid pH (pH from 2.5 to 5 or from 3 to 4).

Preferably, this acid has a boiling point close to the cooking temperature (between 100°C and 170°C; for example either approximately 100°C, or approximately 150°C, or between 100°C and 150°C ), which preferably means a boiling temperature lower than or equal to the cooking temperature expressed in degrees Celsius plus or minus 15% (preferably plus or minus 10%). A preferred acid is an ester of phosphoric acid, such as phosphoric acid dibutyl ester.

A related aspect of the present invention relates to the coating obtainable by the above process.

Preferably, this coating has a thickness of between 1 and 40 μm, preferably between 2 and 20 μm, more particularly between 3 and 10 μm, or even between 3 and 5 μm.

Alternatively, this related aspect of the present invention relates to a coating of a surface which is transparent, bactericidal and virucidal comprising at least 20% by mass of dimethyloctadecyl (3- (trmethoxysilyl)propyl) ammonium and at least 30% by mass of a crosslinking agent being a cyclic organic molecule comprising at least two silane functions which can be hydrolyzed into two silanol groups, said silanol groups having formed a siloxane network with the silyl functions of said molecule being dimethyloctadecyl(3-(trmethoxysilyl)propyl)ammonium.

Preferably, this coating comprises at least 35% (preferably approximately 40% by mass) by mass of the biocidal quaternary ammonium having been incorporated: weight of dimethyloctadecyl (3- (trimethoxysilyl) propyl) ammonium: sum of the weights of the dry constituents of the composition and at least 25% (preferably at least 30 or 35%) by weight of a crosslinking agent (weight of the crosslinking agent: weight of all the dry constituents of the composition).

Alternatively, this coating also comprises a polymer (adjuvant) comprising two silane functions which can be hydrolyzed into silanol groups, one at each of the two ends of the polymer, which is inserted into the siloxane network.

Preferably, this polymer (adjuvant) is a copolymer having segments of different stiffness.

Advantageously, this polymer (adjuvant) has a size of between 500 and 2200 Da (i.e. 300 to 2000 Da of polymer without counting the silane-alkoxy functions), preferably between 700 and 1700 Da (i.e. 500 to 1500 Da of polymer without counting silane-alkoxy functions) or between 700 and 1200 Da (i.e. 500 to 1000 Da of polymer without counting the silane-alkoxy functions).

Preferably, or in addition segments of different rigidity and the possible preferred size, this polymer (adjuvant) is chosen from polyester, polyether, polyurethane, polycarbonate and polyacrylate; polyester being preferred.

Advantageously, this coating makes it possible to reduce the viral load by at least 85%, calculated according to the ISO21702:HCoV-229E standard, preferably at least 90%, at least 95%, or even 99% reduction in the viral load.

Another aspect of the present invention relates to the virucidal use of this coating.

Another aspect of the present invention relates to a glass, a metal surface or a plastic covered by this coating.

Another aspect of the present invention relates to a method for the neutralization of (membrane) viruses, comprising the step of coating a surface with the virucidal coating of the present invention.

Advantageously, this method also comprises the step of harvesting the neutralized viruses.

Another aspect of the present invention relates to a composition (pharmaceutical and/or vaccine) comprising these neutralized viruses.

Other characteristics and advantages of the present invention will be drawn from the nonlimiting description which follows, and with reference to the examples.

Brief description of figures:

Figure 1: effect of quaternary amine concentration

Figure 2: effect of the adjuvant polymer.

Examples.-

Example 1:

A mixture containing 10 g of isopropanol + 3.6 g of Tris[3- (trimethoxysilyl)propyl]isocyanurate + 2 g of 3-Glycidyloxypropyl-timethoxysilane + 3.1 g of dimethyloctadecyl({3- (trimethoxysilyl)propyl) ammonium ( without counting the contaminants; the molecule represents >70% of the composition comprising it, the remainder being methanol and the impurities) is stirred. 59 of H:z0+02 g of dibutyl ester phosphoric acid are added to the mixture to initiate the reactions between the silane (siloxane) functions. The mixture is left stirring for 2 to 4 hours at room temperature. The mass % of dimethyloctadecyl(3-(trimethoxysilyl)propyl)ammonium relative to the dry matter is 35.6%.

Example 2:

A mixture containing 10 g of isopropanol + 3.36 g of Tris[3- (trmethoxysilyl)propyl]isocyanuraite + 2 g of 3-Glycidyloxypropyl-trimethoxysilane + 3.64 g of dimethyloctadecyl(3- (irmethoxysilyl)propyl) ammonium (same composition used only in Example 1) is stirred. 5 g of H20 + 0.2 g of dibutyl ester phosphoric acid are added to the mixture to initiate the reactions between the silane (siioxane) functions. The mixture is left stirring for 2 to 4 hours at room temperature. The mass % of dimethyloctadecyl(3-(trimethoxysilyl)propyl)ammonium)) relative to the dry matter is 40.4%.

Example 3: Application on glass and test

The 2 mixtures are deposited on glass substrates by “spin-coating” followed by baking at 150° C./2 h.

The scratch resistance, the antibacterial effectiveness and the antiviral effectiveness of the two types of coating are evaluated.

The staining test with bromothymol confirms the presence of quaternary ammonium on the surface. A few drops of bromothymol are deposited on each of the coatings for 15 minutes. At the end, the coatings are rinsed several times with water.

The results are shown in Figure 1. Both coatings have very good mechanical properties and provide very good antibacterial activity. The coating with the most of the biocidal quaternary amine exposed on the surface shows exceptional antiviral activity of 99% reduction, compared to 85% reduction for the coating with less of the quaternary amine exposed.

The inventors have attempted to further increase the quaternary amine content (44% by mass; 38% of the crosslinking agent): the antiviral activity is retained, but the mechanical properties of the coating are less good, with some visible scratches .

Example 4 — Adjuvant polymer

The inventors then compared the composition of Example 2 with a composition in which the content of the crosslinking agent is reduced to 25.2% (by weight), and 12.1% (by weight) of a polymer adjuvant (polyester-silane) is added. As shown in Figure 2, the intensity of the blue color is greatly increased, and the antibacterial and antiviral activities are still excellent, as are the mechanical properties and scratch resistance. It is understood that the present invention is in no way limited to the embodiments described above and that many modifications can be made thereto without departing from the scope of the appended claims.

Claims (25)

Amended claims 1. A process for obtaining a transparent coating in which - a cyclic organic molecule is mixed comprising at least two silane functions hydrolysable into two silanol groups and dimethyloctadecyl (3- (trimethoxysilyl) propyl) ammonium in an aqueous solution or a water/water-soluble organic solvent mixture, - this mixture is acidified and allowed to gel, - this gelled mixture is applied to a substrate under conditions allowing crosslinking of the silanol groups formed, in which said cyclic organic molecule is A planar organic cycle and in which said process either further comprises adding to the mixture A polymer comprising two terminal silane functions hydrolysable into silanol groups, or comprising more than 35% dimethyloctadecyl (3- (trimethoxysilyl) propyl) ammonium: weight of said dimethyloctadecyl (3-(trmethoxysilyl)propyl) relative to the sum of the dry constituents. 2. The method according to claim 1, in which the mixture further comprises a molecule comprising a function which can be hydrolyzed into a silanol group and a function allowing adhesion to the substrate, the method further comprising the step of fixing the gelled mixture on the substrate by a physical or chemical means, preferably said Molecule being added in a content by weight of between 5 and 40% (weight of said molecule: dry weight of the mixture), preferably between 10 and 20% by weight. 3. The process according to claim 1 or 2 comprising the step of adding to the mixture a polymer comprising two terminal silane functions hydrolysable into silanol groups, said polymer preferably being a copolymer having segments of different stiffness, and/or preferably chosen from polyester, polyether, polyurethane, polycarbonate, polyacrylate and mixtures thereof, preferably said polymer being added in a content by weight of between 5 and 40% (weight of said polymer: dry weight of the mixture), preferably between 10 and 20% by weight. 4. The method according to any one of the preceding claims, comprising more than 25% of the cyclic organic molecule comprising at least two silane functions hydrolyzable into two silanol groups: weight of said cyclic organic molecule comprising at least two silane functions hydrolyzable into two silanol groups , relative to the sum of the dry constituents, preferably said dry constituents comprising said cyclic organic molecule comprising at least two silane functions hydrolysable into two silanol groups, dimethyloctadecyl (3- (trimethoxysilyl) propyl) ammonium and, if present, the molecule allowing the adhesion of claim 2 and/or the polymer of claim 3, more preferably said dry constituents consisting essentially of said cyclic organic molecule comprising at least two silane functions hydrolysable into two silanol groups, dimethyloctadecyl(3-(trimethoxysilyl )propyl) ammonium and, if present, if present the molecule allowing adhesion of claim 2 and/or the polymer of claim 3 and/or any solid impurities. 5. The method according to any preceding claim, comprising more than 20%, preferably more than 25%, 30%, 35% such as about 40%, in dimethyl octadecyl (3- (trimethoxysilyl) propyl) ammonium: weight of said dimethyl octadecyl (3- (trimethoxysilyl) propyl) ammonium, relative to the sum of the dry constituents, preferably said dry constituents comprising said organic molecule cyclic comprising at least two silane functions which can be hydrolyzed into two silanol groups, dimethyloctadecyl(3-(trimethoxysilyl)propyl) ammonium and, if present, the molecule allowing the adhesion of claim 2 and/or the polymer of claim 3, so as still preferred, said dry constituents consisting essentially of said cyclic organic molecule comprising at least two silane functions which can be hydrolyzed into two silanol groups, dimethyloctadecyl(3-(trimethoxysilyl)propyl) ammonium and, if present, if present the molecule allowing the adhesion of the Claim 2 and/or the polymer of Claim 3 and/or any solid impurities. 6. The method according to any preceding claim wherein the acidified mixture is at a pH between 2.5 and 5.0, preferably between 3 and 4. 7. The process according to any one of the preceding claims, in which the gelled mixture is applied to the substrate by centrifugation (spin coating}, by spraying (spraying), by dipping (dip coating), by sprinkling (flow coating) or by procedure of roll to roll. 8. The method according to any preceding claim, wherein the substrate is glass. 9. The process according to claim 8, comprising the preliminary step of applying a primer layer to the glass, said primer layer consisting of a siloxane network further comprising primary amines or thiol groups, and in which the molecule comprising a function which can be hydrolyzed into a silanol group and a function allowing adhesion to the substrate is present and in which said function allowing adhesion to the substrate is an epoxide, preferably 3-Glycidyloxypropyl)trimethoxysilane; CAS 2530-83-8), OR an acrylate or a methacrylate, said method comprising a final stage of baking on the substrate at a temperature above 100°C, preferably being around 150°C. 10. The method according to any one of the preceding claims 1 to 7 wherein the substrate is plastic. 11. The process according to claim 10 comprising the step of adding to the reaction mixture an acrlate or a methacrylate comprising one or more function(s) hydrolysable into a sianol group and preferably comprising one or more function(s) (tetrahydro) furan, said preferred method preferably further comprising the step of bonding to the substrate by application of ultraviolet radiation or by baking at a temperature compatible for the plastic. 12. The method according to any of the preceding claims 1 to 7 wherein the substrate is metal. 13. The process according to claim 12 comprising the preliminary step of applying a primer layer to the metal, consisting of a siloxane network further comprising primary amines or thiol groups, and in which the molecule comprising a hydrolysable function in a silanol group and a function allowing adhesion to the substrate is present and, preferably in which said function allowing adhesion to the substrate is an acrylate or a methacrylate, preferably said method further comprising a final step of baking on the substrate at a temperature above 100°C, preferably being about 150°C. 14. The process according to any one of the preceding claims, in which the cyclic organic molecule comprising at least two silane functions which can be hydrolyzed into two silanol groups consists of a planar organic cycle, said molecule being Tris[3-(trimethoxysilyl)propyl]isocyanurate; CAS 261 15-70-8. 15. The process according to any one of the preceding claims, in which the solvent is a water:alcohol mixture, preferably water:isopropanol or water:methanol or water:(isopropanol & methanol), preferably in a mass ratio of between 1:1 and 1:5. 16. The process according to claim 6, in which a maximum of 5% by weight of the acid (weight of the acid:weight of the dry constituents) is added to obtain the pH defined in claim 6 and/or in wherein said acid is an acid having a boiling point close to the cooking temperature defined in claims 9, 11 and/or 13, preferably the close boiling point meaning a boiling temperature lower than or equal to the temperature of cooking expressed in degrees Celsius plus or minus 15% (preferably plus or minus 10%) preferably an ester of phosphoric acid, such as phosphoric acid dibutyl ester. 17. The transparent coating obtainable by the process according to any one of the preceding claims 1 to 16, being bactericidal and virucidal and having a thickness of between 1 and 40 μm, preferably between 2 and 10 μm, more preferably between 3 and 5 µm. 18. A coating of a surface, being transparent, bactericidal and virucidal, and having a thickness between 1 and 40 µm, preferably between 2 and 10 µm, more preferably between 3 and 5 µm, comprising at least 20% by mass of dimethyloctadecyl (3- (silyl) propyl) ammonium and at least 20% by mass of a crosslinking agent being a cyclic organic molecule comprising at least two silane functions hydrolysable into silanol group functions, said silanol groups having formed a network siloxane at least with the silyl functions of said dimethyloctadecyl (3- (trimethoxysilyl) propyl) ammonium. 19. The coating according to claim 18 comprising at least 35% (preferably about 40% by mass) by mass of dimethyloctadecyl (3-(silyl)propyl) ammonium and at least 25% by mass of a crosslinking agent. 20. The coating according to claim 18 or claim 19 further comprising a polymer comprising at both ends two terminal silane functions inserted into the siloxane network, said polymer preferably being a copolymer having segments of different stiffness, and/or preferably chosen from polyester, polyether, polyurethane, polycarbonate, polyacrylate and mixtures thereof. 21. The coating according to any one of the preceding claims 17 to 19 allowing the reduction of at least 85% of the viral load, calculated according to standard ISO21702:HCoV-229E, preferably at least 90%, at least 95%, or even 99% viral load reduction. 22. Virucidal use of the coating according to any one of the preceding claims 17 to 21. 23. A surface of glass, metal or plastic covered by the coating according to any one of the preceding claims 17 to 21. 24. A method for the neutralization of membrane viruses comprising the step of covering a surface with the coating according to any one of the preceding claims 17 to 19 and the optional step of recovering said neutralized viruses. 25. Pharmaceutical and/or vaccine composition comprising the neutralized viruses of claim 24.