Homogeneous and stable dispersions of carbon allotropes in water and in an organic solvent, preparation thereof and use thereof in the coating of substrate surfaces

Abstract

A dispersion comprising at least one sp2 carbon allotrope non- functionalized with covalent, bonds, in exfoliated form., is described further comprising a dispersion liquid selected from water, an organic solvent, or combinations thereof; at least one compound capable of adjuvating the exfoliation of said allotrope; at least one optional compound selected from a dispersing agent, a stabilizing agent or a combination thereof; and optionally at least one antimicrobial agent and / or at least one anti foam agent, wherein said at least one compound capable of adjuvating the exfoliation (exfoliant) of said, allotrope is selected from polysaccharides, possibly in the form of salts: polymeric compounds belonging to the polyvinyl pyrrolidone class, possibly in the form, of salts; combinations thereof; and wherein the weight ratio between the allotrope contained in the dispersion and the exfoliant is greater than, or equal to, 0.6, preferably greater than, or equal to, 0.8, more preferably greater than, or equal to, 1, said allotrope in exfoliated form resulting from mechanical exfoliation at high shear stress.

Description

[0001] HOMOGENEOUS AND STABLE DISPERSIONS OF CARBON ALLOTROPES IN WATER AND IN AN ORGANIC SOLVENT, PREPARATION THEREOF AND USE THEREOF IN THE COATING OF SUBSTRATE SURFACES

[0002] DESCRIPTION

[0003] The present invention relates to liquid dispersions, in water and / or organic solvent, of an sp2carbon allotrope in exfoliated form and non-functionalized with covalent bonds, their preparation process and their use, as an additive, in coating compositions, e.g., enamels, paints and the like, of wall substrates or as a coating composition for direct application to textile substrates, e.g., non-woven fabric (NWF), to impart antimicrobial and / or antiviral properties to said substrate.

[0004] In particular, the present invention relates to dispersions as defined above, which are homogeneous and stable (i.e., there is no re-aggregation and precipitation or if this occurs these phenomena are not permanent) and in which the sp2carbon allotrope is selected from those having at least one dimension less than 100 nm such as graphites, nano-graphites, graphene, fullerene, carbon nanotubes, preferably nano-graphites.

[0005] More particularly, the present invention relates to a paint and / or enamel coating for wall or textile substrates containing a dispersion of a nano-graphite non- functionalized with covalent bonds and in exfoliated form, having antimicrobial / antibacterial properties, and its method of preparation. in allotropes of carbon, the carbon can be sp3or sp2hybridised. Carbon is sp3hybridised in diamond while it is sp2hybridised in carbonaceous materials such as carbon black, graphites, nano-graphites, graphene, fullerene, and carbon nanotubes.

[0006] In the following text, a sp2carbon allotrope will also be referred to as a carbonaceous material, without departing from the scope of the present invention.

[0007] Sp2carbon allotropes are defined as "nano" carbonaceous materials when they have at least one dimension less than 100 nm. Graphene and nano-graphites are so-called "nano" allotropes. A nano-graphite (Few Layers Graphite, FLG) consists of crystalline aggregates made up of a few stacked graphene layers. A graphene layer has the thickness of a carbon atom x?ith a nanometre dimension, and the dimension of the crystalline aggregate in the direction orthogonal to the layers ranges from a few nm to a few tens of nanometres.

[0008] To prepare a dispersion of sp2carbon allotropes in a liquid, e.g. water and / or an organic solvent, it is necessary to carry out the operation of mixing the carbonaceous material in the liquid phase. The dispersion is homogeneous and stable if the carbonaceous material is homogeneously distributed in the liquid phase, if it has high dispersibility, and if the dispersion does not undergo phase separation or sedimentation after a sufficiently long period

[0009] It is known in the state of the art that in order to increase the dispersibility of graphite in water, with the aim of obtaining homogeneous and stable dispersions, graphite is oxidised to graphene oxide, in fact, graphene oxide is functionalized with oxygenated groups, such as hydroxyl, carbonyl and epoxy groups, which make it hydrophilic and promote the formation of stable aqueous QJ_SpGI?S1ons<

[0010] Graphene oxide can be prepared from graphite by means of the well-known Hummers method in which graphite is exposed to strongly oxidising conditions in a liquid phase consisting of a mixture of sulphuric acid, potassium permanganate and sodium nitrate. This method produces graphene oxide in the form of nanoplates containing a variable number of stacked layers of graphene oxide.

[0011] The preparation methods based on the Hummers method and its modifications have the disadvantage of being rather complex, dangerous to implement due to the very severe reaction conditions and the type of reagents required, which are expensive and have high environmental impact. In addition, graphene oxide obtained by these methods has variable properties that are strongly dependent on the synthesis conditions adopted. Characteristics such as the acidity of the aqueous solution and the presence of metals make it poorly compatible with substrate coating compositions that contain various adjuvants and additives such as film-forming agents.

[0012] Furthermore, graphene oxide obtained by the Hummers method contains magnesium ions that may negatively influence the properties of this oxide in its subsequent uses.

[0013] Several variants of the Hummers method are also known in which less hazardous reagents are used than those of the original method and which do not release toxic compounds.

[0014] For example, in patent application WO2022180524A1 on behalf of the Applicant, a process is described for preparing an antimicrobial substrate coating composition in which the oxidation of graphite is conducted with hydrogen peroxide in an acidic environment, resulting in a homogeneous aqueous dispersion of only partially oxidised carbonaceous material, which is only compatible with certain film-forming agents, but which leads to coagulation and precipitation in cases of incompatibi1ity .

[0015] Furthermore, this composition also contains metal ions, such as silver, copper and zinc, as antimicrobial agents, which can lead to compatibility problems with the adjuvants and additives in the coating composition, worsening the quality of the final coating, and under certain conditions can generate cytotoxicity on the cells.

[0016] In the state of the art, dispersions containing graphenebased materials, nano-graphite and in particular graphite in oxidised form (graphene oxide, also indicated as GO), are widely used as antimicrobial agents and employed in the preparation of antimicrobial coating compositions. An example of such use is the commercial product "Dr. Wall", by the company Graphene.CA, USA, consisting of a water-based acrylic paint containing a combination of graphene and T1O2.

[0017] Another example for the same application is the graphene oxide dispersions described in WO2022180524A1 on behalf of the Applicant, intended to be added to coating compositions that contain film-forming agents, adjuvants and additives specific to the coating composition.

[0018] Graphene oxide (GO) is the functionalized form (i.e. the oxidized form) of graphene since it contains covalently bonded functionalizations (also defined as "covalent functionalizations") and it belongs to the class of sp2carbon allotrope functionalized with covalent bonds.

[0019] Reduced graphene oxide is obtained from graphene oxide and it is never completely reduced: thus also the reduced graphene oxide (indicated as rGO) contains covalently bonded functionalizations, and thus it belongs to the class of sp2carbon allotrope functionalized with covalent bonds. A limitation of the aforementioned coating compositions lies in the presence of metal ions, which can lead to undesirable phenomena such as accelerated corrosion of metals if they are included in the substrate to be coated.

[0020] A further limitation of nano-graphite dispersions (FLG) known in the art is the widespread use of N-methyl pyrrolidone (NMP) as a solvent to assist in the exfoliation of graphite by sonication, as NMP turns out to be a toxic compound with such a hazard that pictograms are required for its sale.

[0021] Aqueous dispersions of non-functionalized graphene that is exfoliated in the presence of ultrasound are described in literature, in which the amount of graphite used in the dispersion is far less than the amount of exfoliating agent used so as to ensure exfoliation of the graphite.

[0022] However, the higher amount of exfoliating agent compared to non-functionalized graphene can be a problem when graphene dispersions are intended to be added to other compositions such as paints, as the latter contain other additives, e.g. film-forming agents, adjuvants or specific additives, which may be incompatible with the exfoliating agent.

[0023] Furthermore, the use of ultrasound makes the aforementioned dispersions of the prior art unfeasible by industrial processes, as it is difficult to subject large quantities of dispersion to sonication. it is therefore felt the need for dispersions of non- oxidised carbonaceous material, which are fully compatible with the film-forming agents and / or other additives and / or adjuvants used in coating compositions of substrates of the prior art so as not to have phase separation in said coating compositions, and which allow homogeneous coatings to be made on said substrates so as to impart the desired antimicrobial properties and overcome the drawbacks of the nano-graphite dispersions (FLG) known in the state of the art. in particular, it is desirable to have nano-graphite dispersions in water and / or organic solvent as defined above, which are preferably also free from metal ions, in particular silver, zinc and copper ions, and wnicn do nor.underg’o pnase separation or sedimentation for a sufficiently long period of time (shelf-life), e.g. 30 days, so as to achieve consistently homogeneous application of the coating composition and guarantee the desired antimicrobial properties over time.

[0024] It is also highly desirable to have available dispersions of graphene not belonging to the class of the graphene oxide, reduced graphene oxide and graphene with other covalently bonded functionalizations, in particular to have available non-functionalized covalently bonded nano-graphite dispersions (FLG) that include a non-toxic and non-hazardous compound coadjuvant of exfoliation of graphite that is fully compatible with the film-forming agents or other additives present in the substrate coating compositions to which these nano-graphite dispersions are to be added to impart antimicrobial properties to the substrate.

[0025] It is also desirable that the aforementioned stable dispersions of nano-graphites non-functionalized with covalent bonds be obtained by a simple, rapid process involving one-pot exfoliation of the sp2carbon allotrope, so as to be industrially obtainable for large-scale production and also more economically sustainable.

[0026] The Applicant has now found that one or more of these objectives can be achieved by carrying out a process of dispersion of sp2carbon allotropes non-functionalized with covalent bonds, in particular nano-graphite (FLG), in water and / or organic solvent using specific exfoliation adjuvants and possibly specific dispersing and / or stabilising agents, operating under specific conditions, e.g. mixing type.

[0027] An object of the present invention is a dispersion of at least one sp2carbon allotrope non-functionalized with covalent bonds in exfoliated form, i.e. an allotrope not having covalent functionalizations, and thus excluding graphene oxide, reduced graphene oxide, preferably having at least one dimension less than 100 nm, more preferably graphites, nano-graphites, graphene, fullerene, carbon nanotubes, even more preferably nano-graphite (FLG), said dispersion further comprising or containing:

[0028] - a dispersion liquid selected from water, an organic solvent excluding N-methyl pyrrolidone, or combinations thereof;

[0029] - at least one polymeric compound capable of adjuvating the exfoliation of said allotrope; at least one optional compound selected from a dispersing agent, a stabilizing agent or a combination thereof; and optionally

[0030] ■■■ at least one antimicrobial agent and / or at least one antifoam agent, wherein said at least one polymeric compound capable of adjuvating the exfoliation (exfoliant) of said allotrope is selected from the group consisting of polysaccharides, possibly in the form of salts; polymeric compounds belonging to the polyvinyl pyrrolidone class, possibly in the form of salts; and combinations thereof, and wherein the weight ratio between the allotrope contained in the dispersion and said exfoliant is greater than, or equal to, 0.6.

[0031] The above dispersion of sp2carbon allotrope does not comprises rubber latex, e.g. latex of nitrile rubber.

[0032] In such dispersions, the weight ratio of allotrope contained in the dispersion to the exfoliant is preferably less than or equal to 10.

[0033] By "allotrope contained in the dispersion" here we mean the sum of the amount of exfoliated allotrope and allotrope that may not have undergone exfoliation (and which may be in the form of a minimal background residue). This total amount corresponds in practice to the amount of allotrope initially used to prepare the dispersion (nominal amount or concentration of allotrope).

[0034] The total amount of allotrope (exfoliated e possibly non-exfoliated) that is contained in the aforementioned dispersions of the invention can be measured by techniques known to those skilled in the art, for example by gravimetry. in this case, the weight of the dry residue of a weighed sample of dispersion is measured and the weight % due to graphite present = (dry weight / dispersion weight)xlOO is obtained.

[0035] The dryness of the aforementioned sample is obtained by heating the dispersion sample to a temperature such that water and other ingredients that may be present are removed, except for the allotrope, e.g. by heating in air to a temperature greater than 100°C but less than 250~300°C, or by heating in an inert atmosphere to a temperature greater than 100°C.

[0036] In the aforementioned dispersions according to the invention the allotrope in exfoliated form is advantageously derived from high shear mechanical exfoliation in the liquid phase, for example from exfoliation with a Silverson mixer.

[0037] The exfoliation of the allotrope can be verified by UV- Visible analysis with a spectrophotometer by means of comparative analysis involving the comparison of absorption curves at 550nm and 325nm. of two respective dispersion samples. For a given sample, the higher the ratio between the absorbances at 550nm and 325nm, the lower the degree of exfoliation (see also characterisation).

[0038] The above-mentioned dispersions of the invention are liquid at room Temperature.

[0039] Furthermore, the aforementioned liquid dispersions comprising said exfoliated allotrope non-functionalized with covalent bonds are characterised by having a TSI (Turbiscan Stability Index) less than or equal to 1 (measured after at 1east 3 days).

[0040] In particular, the TSI of the dispersions according to the present invention is preferably less than or equal to 0.9, more preferably less than or equal to 0.5 measured after 3 days.

[0041] A low TSI value as defined above measured after 3 days is an indication of a low tendency of the dispersion components to separate. The above-mentioned low TSI values are therefore a preliminary indicator of the stability of the sp2carbon allotrope dispersion without formation of phase separation or sedimentation visible to the naked eye over a period of time greater than 30 days, under conditions of ambient temperature and atmospheric pressure.

[0042] Tn a particular embodiment, the dispersions of the invention also have a TSI less than or equal to 2 measured after 7 days.

[0043] The Turbiscan Stability Index (TSI) measurement of the dispersions of the present invention was performed by means of the Turbiscan Tower instrument and according to a methodology known in the state of the art, which will be briefly described below.

[0044] The dispersions according to the present invention have, as mentioned above, a high weight ratio between the carbon sp2allotrope contained in the dispersion and the exfoliation adjuvant (hereinafter also referred to as "exfoliant" for brevity). This ratio is preferably greater than, or equal to, 0.8, preferably greater than, or equal to, 1.

[0045] In a preferred embodiment, dispersions comprising sp2carbon allotrope in exfoliated form according to the present invention have a weight ratio between the sp2carbon allotrope contained in the dispersion and the exfoliation adjuvant comprised in the range from 0.6 to 10, preferably from 0.8 to 10, extremes included, more preferably from 1 to 6, extremes included.

[0046] The advantage of having available stable dispersions having a high weight ratio of sp2carbon allotrope to exfoliant is to reduce the risks of possible interactions between said exfoliant and the components of coating compositions, e.g. film-forming agents, once the dispersions of the present invention have been added, as additives, to substrate coating compositions.

[0047] Moreover, the stable dispersions according to the present invention have also proven to be homogeneous as well as stable.

[0048] In fact, the UV-visible analysis revealed a content (or concentration) of dispersed allotrope in the exfoliated form that is at least 70% by weight (at time zero) compared to the amount (or concentration) of allotrope contained in the dispersion (at time zero), with a "loss" of allotrope thus less than 30% by weight compared to the amount of allotrope initially loaded before exfoliation.

[0049] The above concentration of dispersed allotrope in exfoliated form can be expressed as mass of dispersed allotrope / nominal mass of allotrope, where

[0050] - the mass of the dispersed allotrope in exfoliated form is preferably determined by UV-visible analysis, correlating the absorbance A of a sample (at X=660nm) to the concentration eg ot dispersed allotrope according to the Lambert-Beer law A™aCgl in accordance with the method provided in the characterization of the examples ; the nominal mass of al lotrope is the amount of allotrope in a not yet exfoliated form that was initially used to prepare the dispers ion .

[0051] This minimum concentration va. lue ( i . e . 70% ) was suf f icient to avo id the need to centri fuge the di spersion of the present invention, an operation that is convent ional ly performed in the state of the art to remove the les s exfoliated portion of graphite .

[0052] Therefore , dispersions in accordance with the present invention are preferably characterised by having

[0053] - a TS i less than or equal to 1 measured after 3 days ; in combination with a concentration ot dispersed allotrope in exfoliated form that is at least 70 % ( at time zero ) with respect to the nominal allotrope concentration at time zero initially loaded (before exfoliation) .

[0054] Furthermore, t h e d i s p e r s i o n s of the present invention have been shown to be reversible in that an y a.11 o t r o p e precipitates in a di spersion sample revert to the dispersed state af ter the sample has been overturned a f ew times or by gentle manual agitation, and the concentration measurement by UV-Visible returns to the initial result (at time zero). This shows that any bottom bodies are temporary (reversible) and that any re-aggregation and precipitation of the exfoliated allotrope layers is neither permanent nor definitive .

[0055] In accordance with the present invention, the singular indefinite article, ''one", is understood to also comprise the meaning of "at least one", unless specified otherwise.

[0056] In the present description of the invention, unless otherwise specified, the values of the ranges include the extremes of the range.

[0057] In the present description of the invention, unless otherwise specified, the percentages (%) are to be understood by weight.

[0058] In the present description of the invention, the term "comprise" includes as a particular limiting case also its meaning as "consisting of".

[0059] In the present description of the invention, the term "essent..13.1.ip cons.isLs oi " mcans tnat

[0060] - the composition or method necessarily includes the listed ingredients or steps; and that

[0061] - the composition or method is open to unlisted ingredients or steps that do not materially affect the basic and innovative properties of the composition or method In the present description of the invention, unless otherwise specified, "part" and "parts" means part by weight and parts by weight, respectively.

[0062] The assessment of the stability of a dispersion by determining the TSI values defined above of a dispersion sample rather chan by visual ooservation of rhe dispersion after certain time intervals (e.g. 24 hours, 7 days, 30 days, 6 months, at room T) is advantageous in that the various destabilisation phenomena in a dispersion are hardly visible to the naked eye. For the human eye, only the final macroscopic effect is appreciable, which is manifested by the clear separation of the phases due to the migration of the allotrope particles (solid component), e.g. nanographite, in the dispersion and their re-aggregation with precipitation, while the particle size change (flocculation and coalescence) is not appreciable to the human eye.

[0063] The particle migration phenomena that the Turbiscan Tower clearly detects are not visually quantifiable mainly due to the fact that the sedimentation thicknesses characteristic of destabilization processes are small.

[0064] The technique on which the Turbiscan Tower is based is known in the state of the art. It consists of sending photons (light) into the sample. After being diffracted several times by suspended particles "backseattered" (Backseattering) and "transmitted" light (Transmission) is detected by appropriately positioned diodes. Any phenomenon occurring in the scattering can be detected and quantified based on measurements of the Backscattering (BS) and / or Transmission (T) signal intensities performed by Turbiscan technology, as both signals depend on the concentration and size of the particles. The transmission (T) and backscattering (BS) intensities are recorded over time over the entire height of the sample to obtain a complete view of its stabi1ity / instabi1ity .

[0065] The calculation of the TSI is based on an algorithm integrated into the measuring instrument (not shown here as it is known in the art) that summarises the evolution of the transmitted light (T) or backscattered light (BS) at each sample position (h), based on the difference from scan to scan, with respect to the total sample height (H).

[0066] High "TSI" values are associated with high dispersion instability, while decreasing "TSI" values are associated with increasing dispersion stability.

[0067] The lower the TSI value, the lower the tendency of the dispersion to destabilize over time.

[0068] The Turbiscan Tower instrument management software classifies dispersion stability according to a TSI scale, defined as follows:

[0069] A+ (TSIt0.5) -> there is no ongoing destabilization, the sample remains visually stable; A (0.5<TSI^l) -> the destabilization is slight to the extent that the visual investigation does not pick up any instability;

[0070] B (K TSI13) ”> although the phenomenon is not yet visually perceived destabilization begins to occur appreciably;

[0071] C (3<TSI^10) the sample shows clear signs of instability due to the presence of sedimentation phenomena, creaming (i.e. particles of the dispersed phase concentrating at the surface, a phenomenon otherwise referred to as "surfacing") and particle size variation;

[0072] D (TSI>10) sedimentation fully visible.

[0073] The water, the organic solvent or combinations thereof are present in the sp2carbon allotrope dispersion of the invention generally in a total amount that is at least 80% by weight with respect to the total weight of the dispersion and advantageously is within the range (% by weight with respect to the total weight of the dispersion) of

[0074] - 80% to 99%,

[0075] -preferably 88% to 98%,

[0076] -more preferably 92% to 97%.

[0077] It is understood that water, solvent or a combination thereof may be present in the dispersions of the invention in amounts of less than 80% by weight with respect to the weight of the dispersion without departing from the scope of the present invention.

[0078] The concentration of the at least one sp2carbon allotrope, preferably having at least one dimension less than 100 nm, more preferably graphite, nano-graphite, graphene, fullerene, carbon nanotubes, even more preferably nano-graphite (FLG), contained in the dispersion of the present invention is at least 0.1% by weight with respect to the total weight of the dispersion and is advantageously within the range {% by weight with respect to the total weight of the dispersion) of

[0079] - 0.1% to 10%,

[0080] -preferably 0.4% to 7%,

[0081] -more preferably 0.8% to 4%;

[0082] - still more preferably from 0,8% to values lower than

[0083] 1,5%.

[0084] The at least one exfoliation adjuvant compound (or hereinafter also referred to as "exfoliant") is present in the dispersion of the invention in such an amount as to achieve th e above-mentioned a11otrope / exfo1iant weight ratio.

[0085] Advantageously, the amount of exfoliant present in the dispersion of the invention is within the range (% by weight of the total weight of the dispersion) of

[0086] -0.1% to 10%,

[0087] -preferably in the range of 0.4% to 5%, - more preferably in the range of 0,4% to 3%, still more preferably in the range of 1% to 3%.

[0088] The at least one dispersing agent, if any, may be contained in the dispersion of the invention as a compound as such or in solution form, without thereby departing from the scope of the present invention.

[0089] Specifically, the dispersant, considered as such, may be contained in the dispersion in an amount in the range (% by weight of dispersant as such to weight of dispersion; of

[0090] - 0.10% to 5%,

[0091] -preferably 0.15% to 4%,

[0092] ■■■more preferably in the range of 0.2% to 2%.

[0093] The at least one stabilizing agent, if present, may be contained in the dispersion of the invention in an amount within the range (% by weight of the total weight of the dispersion) of

[0094] “0.4% to 5%,

[0095] -preferably 0.6% to 4%,

[0096] -more preferably 1% to 3%.

[0097] The presence of at least one dispersant or stabilizer belonging to the classes defined below is advantageous, in general terms, when further lowering the TSI value is desirable. in addition, or alternatively,the presence of at least one dispersant or stabilizer belonging to the classes defined above is advantageous when it is desirable to increase the % of allotrope dispersed in exfoliated form at time zero (measured by UV-Visible analysis).

[0098] In addition, the presence of at least one dispersant or stabilizer belonging to the classes defined above is advantageous when the antimicrobial agent is present, as it results in a dispersion that is less prone to destabilization over time, e.g. obtaining a TS1 less than or equal to 2 measured after 7 days.

[0099] An antimicrobial agent herein is understood to identify any compound known in the state of the art, or any mixture thereof, having antimicrobial and / or antibacterial properties, including antifouling properties.

[0100] The at least one antimicrobial agent, if used, or the combination of antimicrobial agents, if used, is present in the dispersion in an overall amount within the range (% by weight of the total weight of the dispersion) of

[0101] -0.1% to 20%,

[0102] ~prei-erabJ.y 0.oa to 1uo,

[0103] -more preferably 1% to 6%.

[0104] The at least one antifoam agent, if used, is present in the dispersion of the present invention in an amount comprised within the range (% by weight of the total weight of the dispersion) of - preferably 0.02% to 0.3%,

[0105] - more preferably 0.03% to 0.2%.

[0106] The at least one so2carbon allotrooe used in the dispersion of the present invention excludes the presence of covalent functionalizations since it has not undergone chemical reactions so that it is not a graphene oxide or reduced graphene oxide and in general it does not belong to the class of graphene having covalently bonded functionalizations. The at least one sp2carbon allotrope used in the dispersion of the present invention is preferably graphite, more preferably nano-graphite having no covalently bonded functionalizations.

[0107] The terra "nano-graphite" here refers to a "nano" carbonaceous raaterial consisting of crystalline aggregates made up of a few stacked layers or sheets of graphene, e.g. 3-7, but also in larger nurabers, e.g. 30. Also included in the above definition are nano-graphites referred to as "Few Layers Graphite" (FLG), or also referred to as graphene "nanoplatelets" (GNP) containing a variable number of stacked layers of graphene.

[0108] In one embodiment, the starting graphite used to prepare the nano-graphite dispersions of the invention is high surface area graphite (HSAG), such as HSAG Nano 24 graphite, HSAG Nano 27 graphite marketed by Asbury Carbons and having high crystalline order within the structural layers. Preferably, graphite has a surface area in the range from.200 to 500 m2 / g, as determined by the ASTM D 6556 method.

[0109] Preferably, the graphite has a turbostratic structure wiLn a relatively low number of sracKed ravers, e.g. 30 ro 40 (approximately 35), although the number of stacked layers is not binding for the purposes of the present invention.

[0110] Preferably, the lateral dimensions of the graphitic layers are around 300-400 m . The dimensions can be determined, for example, as described in Biomacromolecules 2017, 18, 3978-3991.

[0111] Graphite preferably has a carbon content equal to or greater than 99% by weight. For example, the chemical composition of graphite, determined by elemental analysis, may be as follows: carbon (99.5% weight / weight), hydrogen (0.4% weight / weight), nitrogen 0.1% (weight / weight). in a particularly preferred embodiment, the sp2carbon allotrope is nano-graphite non-functionalized with covalent bonds.

[0112] With respect to the exfoliation adjuvants usable in the present invention, the polysaccharides are preferably selected from those having a weight average molecular weight Mw comprised between 50,000 g / mol and 500,000 g / mol, more preferably between 150,000 and 350,000 g / mol, even more preferably between 190,000 and 310,000 g / mol.

[0113] Examples of polysaccharide usable in the dispersion of the present invention are chitosan, galactan, mannan, pullulan, laminarin, alginic acid, a sodium salt of a polysaccharide such as sodium alginate, or mixtures thereof.

[0114] Preferred polysaccharides are chitosan and sodium alginate.

[0115] In the case of using chitosan as an exfoliation adjuvant, in order to promote its solubilization, a solubilizing agent, e.g. gJ.aciaz aceuic acici (so1uo11izing agenL} / is preferab1y added to the water and / or organic solvent of the dispersion, in an amount ranging from 5% to 90% by weight, preferably from 10% to 60% by weight, more preferably from 15% to 40% by weight witn respect to one weight of tne cnitosan.

[0116] When a polysaccharide is used as the sole exfoliant, the dispersion of the present invention preferably also contains a dispersant or stabilizer.

[0117] Polymeric compounds belonging to the polyvinyl pyrrolidone (PVP) class that can be used as an exfoliation adjuvant in the present dispersion are miscible with the dispersion solvent used in the present dispersion of the invention, e.g. water, alcohols. Said polymeric compounds generally have general formula (I):

[0118] (I) - n denotes the number of repeating units contained within the structure (I) of the polymer and is an integer equal to at least 20, preferably comprised between 20 and 20,000, more preferably between 45 and 5,000, still more preferably between 90 and 500.

[0119] The weight average molecular weight Mw of the PVP of formula (I) is preferably comprised between 2,200 g / mol and 2,200,000 g / mol, more preferably between 5,000 and 550,000 g / mol, even more preferably between 10,000 and 60,000 g / mol.

[0120] The preferred PVP grades are PVP K30 (having an Mw around 40,000 Daltons) and PVP K10 (having an Mw around 10,000 Daltons).

[0121] Another example of an exfoliation adjuvant compound belonging to the class of polyvinyl pyrrolidones is polyvinylpyrrolidone iodine, also known as iodopovidone (PVPI) and commonly used as an antimicrobial agent, lodopovidone (PVPI) is a complex obtained by combining a polyvinylpyrrolidone (PVP) polymer with iodine.

[0122] The above polymeric compounds belonging to the class of polyvinyl pyrrolidones and the above polysaccharides are not polymers modified with strong anchoring groups and do not belong to the class of the grinding resins and griding media. it is understood that other water-soluble polymers of a hygroscopic nature known as adhesives, ceramic dispersants, may be used as exfoliation adjuvants in dispersions in accordance with the present invention, without departing from the scope of the present invention.

[0123] A "dispersing agent" is identified here as any surfactant that, when added to a suspension, promotes the dispersion of the individual particles of solid material that make up the dispersed phase (e.g. graphite;.

[0124] The dispersing agents that may be contained in the dispersion of the present invention are, as mentioned above, non-ionic or anionic surfactants chosen from among:

[0125] - surfactants containing one or more repetitive units derived from ethylene oxide and / or propylene oxide (degree of ethoxylation or degree of propoxylation).

[0126] ■■■ surfactants used to disperse inorganic / organic pigments;

[0127] - sodium dodecyl sulphate;

[0128] ~ ligno-sulfonic surfactants, e.g. the ligno-sulfonic surfactants marketed by Borregaard;

[0129] - olefinic polymeric surfactants;

[0130] - surfactants belonging to the class of alkyl chain phosphates .

[0131] Examples of compounds useful as dispersants in water and / or organic solvent, comprising one or more repetitive units derived from ethylene oxide and / or propylene oxide are -ethoxylated or polyethoxylated phenols;

[0132] - ethoxylated or polyethoxylated alcohols,

[0133] - ethoxylated / propoxylated or po1yethoxy1ated / po1ypropoxy1ated a1coho1s.

[0134] Among the ethoxylated phenols that can be used as dispersants, the preferred ones are:

[0135] - tristyrylphenol ethoxylate, e.g. "Soprophor", with a degree of ethoxylation comprised between 3 and 6)0, preferably between 3 and 25, more preferably between 3 and 18;

[0136] ■■■ 4-alkylphenol ethoxylates, preferably ethoxylated 4- tert-octylphenol, preferably ’with a degree of ethoxylation of 10, known under the trade name Triton X100.

[0137] Among the ethoxylated or ethoxylated / propoxylated alcohols, products derived from synthetic alcohols with a number of carbon atoms in the alkyl chain from 4 to 22 and degrees of ethoxylation / propoxylation from 4 to 25, or fatty alcohols with degrees of ethoxylation / propoxylation from 5 to 25, can be used for the purposes of the present invention.

[0138] Examples of dispersants belonging to the above classes include EXOdis PC416 (Tristyrylphenol ethoxylates), EXOdis PC417 (Ethoxylated alkylarylphenol phosphorus ester).

[0139] For the purposes of the present invention, other compounds useful as dispersants are commercial products used to disperse inorganic / organic pigments such as Metolat 392

[0140] (Anionic Olefinic Polymer), Metolat 388 (Polyglycol esters), Tego Dispers 685 (high molecular weight polymer), Tego Dispers 740 W (non-ionic compound).

[0141] The aforementioned dispersing agents are known to be used as surfactants in coating compositions with the function of keeping normally present pigment particles dispersed, preventing th.eir re-aggregation and precipitation.

[0142] The term "stabilizing agent" is used here to identify any substance, e.g. emulsifier, surfactant, that hinders the separation of the components of the dispersion into distinct phases, thereby promoting wettability at the interface of the solid components of the dispersion.

[0143] The stabilizing agents present in the dispersion of the present invention are non-ionic or anionic polymeric compounds of various molecular masses, containing one or more -OH groups, such as polyvinyl alcohol (PVA) and preferably also containing repetitive units derived from ethylene oxide or propylene oxide or ethylene groups, for example polymers belonging to the following classes:

[0144] —poiyetry1ene giycoi (PnG.i;

[0145] -polypropylene glycol;

[0146] -polyalkyleneglycols (PAGs), e.g. Rokolub 60-D-150.

[0147] PEG is a linear polymer of general formula (II) that is very soluble in water, derived from the polymerization of ethylene oxide.

[0148] (II)

[0149] - n denotes the number of repeating units within the polymer structure and is an integer comprised between 4 and 250, preferably between 6 and 150, more preferably between 8 and 30.

[0150] The weight average molecular weight Mw of the PEG of formula II is comprised between 200 g / mol and 11,000 g / mol, preferably between 280 and 6,600 g / mol, more preferably between 370 and 1,300 g / mol.

[0151] The preferred polyethylene glycol of formula (II) is PEG 400 characterized by an Mw value of 400.

[0152] PAG is a linear polymer of general formula (III), derived from the polymerization of a mixture of ethylene oxide and propylene oxide.

[0153] (Ill)

[0154] The higher or lower solubility in water or organic solvent is determined by the relative content of the oxoethylene and oxo-propylene units, where the latter increase the solubility in organic solvent.

[0155] The weight average molecular weight Mw of the PAG is comprised between 500 g / mol and 30,000 g / mol, preferably between 2,000 g / mol and 20,000 g / mol, even more preferably between 4,000 g / mol and 16,000 g / mol.

[0156] The content of oxy-ethylene chains in the PAG is greater than 40%, preferably greater than 50%, more preferably greater than 70%, the above percentages being weight percentages referring to the total weight of oxy-ethylene and oxy-propylene chains in the PAG.

[0157] Polyvinyl alcohol (PVA) is a water-soluble polymer of general formula (IV) obtained by hydrolysis of polyvinyl esters, such as polyvinyl acetate.

[0158] (IV)

[0159] The weight average molecular weight Mw of the PVA of formula (IV) is comprised between 5,000 g / mol and 200,000 g / mol, preferably between 20,000 and 100,000 g / mol, more preferably between 40,000 and 80,000 g / mol.

[0160] Furthermore, being derived from polyvinyl acetate, PVA can be fully or partially hydrolysed, preferably fully hydrolysed.

[0161] The use of the specific exfoliation adjuvants listed above in combination with the use of high shear mechanical exfoliation has resulted in dispersions that are not only characterised by high stability over time, assessed in terms of TSI, but also by high compatibility with the coating compositions, the latter being assessed, in the case of antimicrobial coatings, in terms of the reduction of the total number of living microbes in contact with the coating (% of effectiveness of antimicrobial properties). See the examples.

[0162] The optional antifoam agent enables the control of any foam formation both during the preparation process of said dispersion and during its use in the preparation of an antimicrobial coating composition.

[0163] Antifoam agents can be based on dimethylpolysiloxanes, or mixtures of dimethylpolysiloxanes with alkylacrylates or propoxylated alcohols.

[0164] The water in the dispersion according to the invention can be demineralized water, industrial water, drinking water or combinations thereof.

[0165] The demineralized water preferably has an electrical conductivity value comprised in the range from 20 microS / cm to 100 microS / cm, more preferably in the range from 30 microS / cm to 50 microS / cm.

[0166] The industrial and / or drinking water preferably has an electrical conductivity value comprised in the range from 3000 microS / cm to 100 microS / cm, more preferably in the range from 500 microS / cm to 50 microS / cm.

[0167] In a preferred embodiment, the water is demineralized with an electrical conductivity value comprised in the range from 30 microS / cm to 50 microS / cm.

[0168] Examples of organic solvents that can be used in the dispersion of the invention include aliphatic alcohols (mono-alcohols, diols, polyols), aliphatic esters of carboxylic acids, alkyl ethers, cyclic ethers, e.g. dioxane, alkylaromatic ethers, e.g. anisole .

[0169] The alcohols include, for example, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, preferably isopropanol.

[0170] The esters include, for example, ethyl acetate, a-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, methyl propionate, ethyl propionate, ethyl acetate being the preferred one.

[0171] In one embodiment of the invention, the organic solvent is an alcohol, preferably isopropanol.

[0172] The choice of water or organic solvent as the medium in which to disperse the sp2carbon allotrope, preferably graphite, depends on the type of coating composition, waterbased or solvent-based, to which the dispersion of the present invention is to be added.

[0173] The optional antimicrobial agent may be any compound known in the art having antimicrobial and / or antibacterial properties. This antimicrobial agent may be added to impart or reinforce the antimicrobial properties of the nanographite dispersion containing the exfoliation adjuvant and optionally the dispersant / stabilizer in accordance with the present invention.

[0174] The antimicrobial agent can be selected, for example, from:

[0175] - polysaccharide with antimicrobial properties, such as those previously described among the exfoliation adjuvants, preferably chitosan, galactan, mannan and laminarin, but also a sodium salt of a polysaccharide such as sodium alginate; preferably chitosan and sodium alginate;

[0176] - quaternary ammonium salt containing an ammonium ion of formula [NR4]4C1" wherein the R groups, equal or different to each other, may be alkyl, aromatic, alkylaromatic groups having a number of carbon ranging from 4 to 22;

[0177] - quaternary ammonium salts with a polymer structure containing a plurality of ammonium ions in the polymer chain;

[0178] - polyvinylpyrrolidone iodine already described above among the exfoliation adjuvants;

[0179] - polyglycols, PEG and PAG, previously described among the dispersion-stabilizing agents of the invention, which can also be used as antimicrobial agents .

[0180] The quaternary ammonium salts can be chosen from : quaternary ammonium salts containing an ammonium ion and containing benzyl groups and having hydrocarbon chains of various lengths ( e . g . benzal konium chloride , benzetnonium chloride , benzal konium. brontide ) ; preferably benzalkoni urn s a 11 , more preferably benzalkonium, chloride (BAG ) . quaternary ammonium, sal ts containing an ammonium, ion and containing alkyl groups having a number of carbon atoms ranging from 10 to 22 ( e . g . , Didecyl Dimethyl

[0181] Ammonium Chloride such as BTC® 1010--E ) quaternary ammonium salts having a polymeric structure and containing a plurality of ammonium ions in a chain .

[0182] Preferably, the quaternary ammonium salts containing an ammonium ion and a benzyl group have the following general formula (V) : wherein :

[0183] Ri and R2are independently an alkyl group containing a. number of carbon atoms comprised between 1 and 10 , preferably between 1 and 5 even more pref erably between

[0184] 1 and 2 ; R3is an alkyl group containing a number of carbon atoms comprised between 1 and 10, preferably between 1 and 5 and even more preferably between 1 and 2; n is an integer comprised between 1 and 20, preferably between 6 and 15 more preferably between 8 and 12;

[0185] X represents a halogen counterion selected from fluorine, chlorine, bromine, iodine, preferably chlorine and bromine, even more nreferablv chlorine.

[0186] Quaternary ammonium salts with a polymeric structure can be, for example, yme salts SUCh polydiallyldimethylammonium halides with the following general formula (VI): wherein:

[0187] Ri and R2are an alkyl group containing a number of carbon atoms from 1 to 10, preferably from 1 to 5 and even more preferably from 1 to 2; n denotes the number of repeating units within the polymer structure and is an integer comprised between 100 and 3000, preferably between 500 and 2500, more preferably between 1000 and 2000; X represents a halogen counterion selected from fluorine, chlorine, bromine, iodine, preferably chlorine and bromine, even more preferably chlorine.

[0188] The weight average molecular weight Mw of the salts of formula. (V) is preferably comprised between 20, 000 g / mol and

[0189] 1 , 000 , 000 g. / mo 1 , more preferably between 80,000 and 600,00 g / mol , even more p r e f era b 1 y b e t w e e n 200, 000 and 350, 000 g / mol . if present, the antimicrobial agent is a compound other than the exfoliation adj uvants and stabilizing / dispersing agents with the antibacterial properties described above

[0190] For example, if the exfoliation adjuvant is chitosan, which itself also has antimi c r ob i a 1 properties , and the stabilizing agent is a PEG, which itself also has antimicrobial properties, then the antimicrobial agent is a compound not belonging to the chitosan and PEG classes.

[0191] In general, the antimicrobial agent, or a combination of microbial agents, may be present in the dispersion of the present invention in an overall amount comprised in the range

[0192] (% by weight of total weight of the dispersion) of

[0193] - 0.1% to 20%,

[0194] -preferably 0.5% to 10%,

[0195] - more preferably 1% to 6%. in an embodiment, the dispersion of the present invention comprises (% by weight of the total weight of the dispersion) :

[0196] - water, organic solvent or a combination thereof 80% - 99%,

[0197] ~ graphite 0. l%-10%,

[0198] - exfoliation adjuvant (chitosan or PVP) 0. l%-10%

[0199] - d i s p e r s i n g a. g e n t 0.10%~5%, o r

[0200] - stabilizing agent 0.4-5%; and o p t i o n a. J.1 y

[0201] - antimicrobial agent 0. l%-20%, anti foam agent 0.01%-0.5% wherein the weight ratio between the graphite and the exfoliation adj uvant is greater than, or equal to. 0.6, preferably greater than, or equal to, 0.8, mo re prefer a b 1 y greater than, or equal to, 1, the sum of the percentages of said components present in the dispersion being 100%, such dispersion being capable ot comprising a combination of said dispersant and said stabilizer.

[0202] In another embodiment, the dispersions of a sp2carbon allotrope according to the invention comprise (% by weight with respect to the total weight ot the dispersion) :

[0203] - water, organic solvent or a combination thereof 88% - 98%,

[0204] - graphite 0.5%-7%,

[0205] - exfoliant (e.g. Chitosan or PVP) 0.4%-5%,

[0206] - dispersing agent, e.g. tristyrylphenol ethoxylate, 0.15%-

[0207] 4%, or

[0208] -stabilizer, e.g. PEG 400, 0.6-4%; and optionally

[0209] ~ antunicrobiai agent., e.g. BAG, 0.5%—10%,

[0210] - antifoam agent Q.02%-0.3% wherein the weight ratio between the graphite and the exfoliation adjuvant is comprised in the range from 1 to 10, extremes included, more preferably from 1 to 6, extremes included, 100% being the sum of the percentages of said components present in the dispersion, said dispersion being able to comprise a combination of said dispersant and said stabilizer.

[0211] In yet another embodiment, the dispersions of a sp2carbon allotrope according to the invention comprise (% by weight with respect to the total weight of the dispersion):

[0212] - water, organic solvent or a combination thereof 92%-97%,

[0213] -graphite 0.8%-4%,

[0214] ~ exfoliation adjuvant (chitosan or PVP) l%-3%,

[0215] - dispersant, e.g. tristyrylphenol ethoxylate 0.2-2%,

[0216] -stabilizer, e.g. PEG 400, 1-3%, and optiona11y

[0217] - anL.1.mj.crob1a1 agent., e.g. BAG, 1% 6r,

[0218] - antifoam agent 0.03%-0.2% wherein the weight ratio between the graphite and the exfoliation adjuvant is comprised in the range from 1 to 10, extremes included, more preferably from 1 to 6, extremes included, 100% being the sum of the percentages of said components present in the dispersion, said dispersion being able to comprise a combination of said dispersant and said stabilizer.

[0219] Tn yet another embodiment, the dispersions of a sp2carbon allotrope according to the invention comprise (% by weight with respect to the total weight of the dispersion): water, organic solvent or a combination thereof 92%-97%, ■■■graphite 0.4%-4%,

[0220] -exfoliation adjuvant (chitosan or PVP) 0.4%~3%, wherein the amount of graphite and exfoliant is selected such that the weight ratio between the graphite and the exfoliation adjuvant is at least 0.6, the sum of the percentages of these components in the dispersion being 100%.

[0221] It is understood that dispersions as described above but having an allotrope / exfoliant weight ratio of less than 0.6 in which the exfoliated allotrope is derived from high shear mechanical exfoliation can be obtained and used, even if less advantageous, without departing from the scope of the present invention.

[0222] The dispersions of the present invention, as well as the specific ones as reported above, may also comprise at least one further additive such as, for example, one or more acidity regulators which increase the pH of the dispersions of the invention in case the pH thereof, generally around 4- 5 or even lower, should be raised from an acidic pH to a basic pH, e.g. around 8-10, in order to make the dispersions of the invention apt to be added to formulations having a basic pH, for example paint formulation which generally have a pH around 8-10.

[0223] The one or more acidity regulators that can be used in the dispersions of the invention can be those known in the art, such as for example alkaline bases, e.g. NaOH.

[0224] Other acidity regulators that can be used in the dispersions of the invention can be aminoalcohols, aminoacids or combinations thereof.

[0225] Among aminoacids, preferred are those belonging to the class of highly basic aminoacids, e.g. lysine, arginine, histidine, preferably lysine.

[0226] Examples of aminoalcohols are as follows: 2-amino-2 methyl-l-propanol (APM) of formula 2-ainino-2-ethyl-l , 3-propandiol (AhlPD) of formula

[0227] 2 -dimethyl amino -2 -methyl propanol ( DIAAM P ) of f o rmu 1 a

[0228] Tri (hydoxymethyl ) amino methane of formula

[0229] Other examples of acidity regulators are the fo llowing :

[0230] Poly (oxypropylene)diamine of formula wherein n is an integer number such as to obtain a prefixed average numerical molecular weight (Mn), e.g. about 2,000.

[0231] The above-mentioned acidity regulators are particularly useful when it is required to increase the compatibility, in terms of pH, of the dispersions of the present invention with the formulations to which the dispersions are to be added.

[0232] The acidity regulator can be used in amounts that depend on the type of regulator and on the final pH basic value which is required to be reached.

[0233] In one embodiment of the invention, the one or more acidity regulators can be used in a total amount ranging from 0.01% by weight to 1.5% by weight, preferably in an amount lower than 1% by weight, more preferably lower than 0.1% b y we i gh t , i . e . 0.09% by weight, w i t h r e s p e c t to t h e total weight of dispersion.

[0234] In one embodiment of the invention, the dispersion comprises (% by weight of the total weight of the dispersion) :

[0235] - water, organic solvent or a combination thereof 80%-99%

[0236] - graphite 0. l%-10%,

[0237] - exfoliation adjuvant (chitosan or PVP) 0.1%— 10%

[0238] - dispersing agent 0.10%-5%, or

[0239] ■■■ stabilizing agent 0.4--5%; and optionally

[0240] - antimicrobial agent 0. l%-20%, antitoam agent 0.01 %- 0.5%; acidity regulator from 0.01% to values <0.1% wherein the weight ratio between the graphite and the exfoliation adj uvant is greater than, or equal to, 0.6, preferably greater than, or equal to, 0.8, mo r e p r e f e r ab 1 y greater than, or equal to, 1, the sum. ot the percentages of said components present in the dispersion being 100%.

[0241] Further subject matter of the present invention is to provide a process for preparing a homogeneous and. time-stable dispersion in water and / or organic solvent of a sp2carbon allotrope non-functionalized wi th covalent bonds and i n exfoliated form, preferably having at least one dimension less than 100 nm, more preferably graphite, nano-graphite, graphene, fullerene, carbon nanotubes, even more preferably nano-graphite (FLG), said process comprising the following sequential steps:

[0242] (a) dispersing in water, in an organic solvent as above defined or in a combination thereof, under agitation, an sp2carbon allotrope non-functionalized with covalent bonds, in the presence of a compound adapted to assist the exfoliation of said allotrope which is selected from polysaccharides possibly in the form of salts, polymeric compounds belonging to the class of polyvinyl pyrrolidones or combinations thereof, and optionally in the presence of at least one compound selected from a dispersing agent as defined above, a stabilizing agent as defined above, or a combination thereof, and optionally in the presence of at least one antimicrobial agent and / or at least one antifoam agent and / or an acidity regulator as defined above;

[0243] (b) subjecting the dispersion obtained in step (a) to mixing by mechanical homogenization at high shear stress, mixing said dispersion obtained in step (a) at a mixing speed greater than or equal to the speed of the preceding step (a), preferably at a speed comprised in the range from 1,000 rpm to 10,000 rpm, in order to obtain a liquid dispersion comprising said sp2carbon allotrope in exfoliated form.

[0244] The above steps (a) and (b) can be conducted sequentially or simultaneously.

[0245] Furthermore, the above components of the dispersion may be added to water and / or organic solvent in any order and / or mixed in any order, without departing from the scope of the present invention.

[0246] Tn the process described above, the amount of sp2carbon allotrope to be added and that of exfoliation adjuvant are selected such that their weight ratio is preferably greater than, or equal to, 0.6, more preferably greater than, or equal to, 0.8, even more preferably greater than, or equal to, 1.

[0247] The process described above and the ingredients used therein as defined above nave resulted in liquid dispersions of sp2carbon allotropes in water and / or organic solvent that are homogeneous and stable, with a TSI (Turbiscan Stability Index) value less than or equal to 1 (measured after 3 days), preferably a TSI value less than or equal to 0.9, more preferably less than or equal to 0.5 (measured after 3 days).

[0248] Furthermore, the Applicant has found that due to the mechanical mixing at high shear stress in combination with the specific exfoliation adjuvants (and possibly with the specific dispersants / stabilizers as defined above), not necessary to carry out a centrifugation step of the dispersion to remove the remaining non-exfoliated starting graphite as is the case in the art. In fact in the prior art there is an intermediate step of centrifuging the dispersion to separate the supernatant phase from the non-exfoliated graphite, which can then be redispersed by exfoliation so as to ensure that the entire amount of graphite initially used (nominal amount) has been exfoliated.

[0249] Tn general, steps (a) and (b) described above can be conducted sequentially or simultaneously, without departing from the scope of the present invention. in general, the above-mentioned components of the above- mentioned liquid dispersion may be added to water and / or organic solvent in any order and / or mixed in any order, without departing from the scope of the present invention.

[0250] The duration of the homogenization step at high shear stress of step (b) is preferably comprised in the range from 0.5 hour to 12 hours, more preferably in the range from 0.5 to 8 hours, even more preferably in the range from 0.5 to 6 hours.

[0251] The dispersions of the invention obtained after step (b) have a graphite content in exfoliated form that is at least 70% by weight (at time zero) with respect to the nominal amount of graphite, as previously defined in the text.

[0252] The stabilizing, dispersing, antimicrobial, antifoam and acidity regulator additives, if present, can be added as such to the water / organic solvent.

[0253] Alternatively, an aqueous or solvent solution / dispersion of each of said stabilizer, dispersing, antimicrobial antifoam and acidity regulator additives may be added to said water or organic solvent without departing from the scope of the present invention.

[0254] In the process described above, mechanical homogenisation at high shear stress and / or agitation is carried out by at least one rotor-stator mixer, preferably a Silverson-type mixer. in a preferred form of the process according to the present invention, the preparation of the dispersion comprises the following steps in sequence

[0255] ■■■ step (a) as defined above comprising the following sub- steps: ai) mixing at least one exfoliation adjuvant as defined above with water, or organic solvent or a combination thereof, optionally in the presence of a solubilizing agent of said exfoliation adjuvant as defined above, e.g. acetic acid, preferably mixing at a speed greater than 1000 rpm; a?) dispersing the sp2carbon allotrope nonfunctionalized with covalent bonds, preferably graphite as defined above, more preferably nano-graphite, into the mixture obtained in aJ ; a3) subject the dispersion obtained in step 32) to mechanical homogenization at high shear stress while continuing mixing at a speed greater than 1000 rpm so as to carry out pre-mixing of allotrope-exfoliation adjuvant;

[0256] 34) optionally adding to the mixture obtained in the previous step 33) at least one dispersing agent and / or one dispersion-stabilizing agent as defined above, and optionally at least one antimicrobial agent and / or one antifoam agent and / or acidity regulator as defined above, while maintaining a homogenizing mixing speed greater than 1000 rpm for a predetermined time; b) subjecting the dispersion from step 34) (or from step 33) if step 34) has not been carried out) to mechanical homogenization at high shear stress by mixing, for a predetermined time, said dispersion with a higher mixing speed than that used in the preceding steps ai)-a«) to obtain a dispersion comprising graph!te / nano-exfoliated graphite (FLG) non-functionalized with covalent bonds.

[0257] In general, the dispersing agent, the stabilizing agent, the antimicrobial agent and the antifoam agent, when added in step a4), can be added and mixed in any order, and be used as such or in aqueous solution and / or in solvent, without departing from the scope of the present invention.

[0258] Furthermore, the chosen amount of each component of the dispersion may be added by a single addition, or added in aliquots, each aliquot being added preferably under agitation as indicated above, without thereby departing from the scope of the present invention.

[0259] In the aforementioned process according to the present invention the sp2carbon allotrope, preferably nanographite, water and / or the organic solvent, the exfoliation adjuvant, the dispersing agent and / or the stabilizing agent, the antimicrobial agent, the antifoam agent and acidity regulator are used in such quantities as to obtain a concentration of the individual components within the ranges described above.

[0260] The mechanical homogenization at high shear stress of step a3) and step a«) performs a mixing of the sp2carbon allotrope dispersion at a mixing speed preferably at least equal to 2,000 rpm, more preferably at least 2,500 rpm.

[0261] The maximum mixing speed of each process step described above is generally 10,000 rpm, preferably 9,000 rpm, more preferably 6,000 rpm.

[0262] In an embodiment, the mixing speed is comprised in the range from 2,500 rpm - 9,000 rpm, more preferably in the range 3,000 rpm - 7,000 rpm.

[0263] Tn an alternative embodiment of the process of the present invention, it can be envisaged to mix under agitation all the components of the dispersion with the exception of the allotrope, to then add this allotrope as the last component under agitation, and to subject the resulting mixture to homogenization by mechanical mixing at high shear stress, with a higher mixing speed than that used in the previous steps.

[0264] Homogenization and mixing at high shear stress, or at least mechanical mixing causing exfoliation of the allotrope, can be achieved with commercially available conventional devices such as rotor-stator mixers, such as those marketed by the company Silverson. These mixers comprise a mixing element (rotor) at high speed (typically 10 to 50 m-s"1) and a fixed element (stator) which are positioned in close proximity to each other so that the gap between the end of the rotor and the walls of the stator is very narrow, typically from 100 micrometres to 3 millimetres.

[0265] Mechanical homogenization at high shear stress allows the use of devices conventionally used in industrial processes, thus making the present process of preparing dispersions according to the present invention industria1izab1e .

[0266] The step as) of pre-mixing between the exfoliation adjuvant compound and the sp2carbon allotrope is advantageous in that it promotes and speeds up the interaction (adsorption) between the exfoliating agent and the sp2carbon allotrope to be exfoliated.

[0267] The temperature at which steps a), b), and / or steps ai)- a,j) are conducted is comprised in the range from 25°C to 90°C, preferably in the range from 35°C to 85°C, more preferably in the range from 50°C to 70°C.

[0268] Preferably, the aforementioned temperature is the autogenous temperature determined in the respective process step due to the mixing at high shear stress to which the dispersion is subjected.

[0269] Preferably, steps a), b), and / or steps ai)-a{) are carried out at an absolute pressure in the range from 0.5 bar to 2 bar, more preferably in the range from 0.8 bar to 1.2 bar, even more preferably at atmospheric pressure. it is also possible to envisage operating at a slightly higher pressure than atmospheric pressure by means of nitrogen pneumatization in the case of an organic solvent, without departing from the scope of the present invention.

[0270] At the end of step b), a dispersion of sp2carbon allotrope is obtained in an exfoliated preferably nanographite (FLG) form, which is homogeneous and stable, showing no phase separation or sedimentation visible to the naked eye over a relatively long period of time (at least 30 days) under ambient temperature and atmospheric pressure conditions, evaluated in terms of TSI as defined above.

[0271] It is therefore a further object of the invention to provide dispersions of sp2carbon allotrope in exfoliated form, preferably nano-graphite (FLG), obtainable by the preparation process described above.

[0272] The sp2carbon allotrope dispersions in exfoliated torrs, preferably nano-graphite (FLG), obtainable with the present preparation process are also characterized not only by a TSI of less than or equal to 1 measured at 3 days but also advantageously by a high weight ratio of allotrope to exfoliation adjuvant as defined above.

[0273] Furthermore, dispersions according to the present invention have also been shown to impart antimicrobial properties when directly applied to textile substrates, e.g. NWF, by airbrush spraying, impregnation or other similar techniques.

[0274] Accordingly, dispersions according to the present invention may be used in the preparation of a coating composition of a substrate or be used as such by direct application to textile substrates to impart antimicrobial properties to the surface of said substrate due to the presence of nanometric particles of sp2carbon allotrope.

[0275] In a preferred embodiment, the dispersions of the invention are used for the preparation of an antimicrobial coating composition, such as common water-based paints, solvent paints or enamels to impart antimicrobial properties to a wall substrate.

[0276] Tn another preferred embodiment, the dispersions according to the present invention are applied directly onto textile substrates, e.g. NWF, according to techniques known in the art of textile coating, e.g. airbrush spraying, impregnation (soaking) and the like.

[0277] Non-limiting examples of film-forming agents which may be used for the purposes of the present invention are: acrylic resin, vinyl resin, styrenic resin, alkyd resin, epoxy resin, polyester resin, polyvinyl acetate resin and combinations thereof.

[0278] The nano-graphite dispersion according to the invention was found to be compatible with the film-forming agents contained in a common paint or enamel, i.e. it can be mixed with a common paint or enamel in a wide range of concentrations. The film-forming agent contained in a common paint or enamel has the function of promoting the formation and adhesion of a coating film on the surface of the substrate which is to be made antimicrobial.

[0279] Therefore, further subject matter of the present invention is a coating composition having antimicrobial properties comprising the exfoliated sp2carbon allotrope dispersion according to the invention and a common paint or enamel.

[0280] Tn the antimicrobial coating composition, the paint or enamel may be present in an amount comprised in the range (% by weight of paint or enamel to total weight of coating composition) l%-99%, preferably 3%-90%, more preferably 10%-80%, the remaining portion to reach 100% being the dispersion in accordance with the present invention.

[0281] The paint or enamel included in the antimicrobial coating composition according to the present invention optionally comprises convent Iona 1 additives of the type general ly employed in the formulation of coating compositions, such as , for example, colouring agents (pigments or dyes ) , solvents, coalescing agents , surfactants , thickeners , rheology modifiers, compatibilizing agents and the like.

[0282] The coating composition having antimicrobial properties of the present invention can be prepared by a process comprising mixing an sp 9 carbon allotrope dispersion, e . g . , n a n o ~ g r a p n i t e , as defined above and in accordance with the present invention, with a paint or enamel.

[0283] The process for preparing the antimicrobial coating composition according to the present invention can be carried out with conventional devices and equipment known to a person skilled in the art.

[0284] Preferably, the mixing of the dispersion according to the invention with the paint or ename 1 i s carried, out at room. temperature us ing a Cowles mechanical agitator, commonly used in the paint industry, with a mixing speed comprised in the range of 300 rpm to 1500 rpm, preferably in the range of 800-1300 rpm.

[0285] In order to impart antimicrobial properties to the surface of a substrate, the coating composition according to the present invention having antimicrobial / antibacterial properties may be applied by a technique selected from those generally employed in the painting industry, such as spraying, dipping or by means of a brush, suitable for depositing the coating composition, which is in liquid form, on the surface of subsirate.

[0286] After application of the coating composition according to the present invention, or the dispersion of the present invention directly onto textile substrates, the liquid phase contained in the composition (or dispersion) is evaporated to form a suitably cured and / or dry coating film on the substrate. Generally, evaporation of the liquid phase is achieved by exposure to air, at room temperature or above. To reduce the times for drying and formation of the coating, the coating composition can be dried in an oven.

[0287] Examples of substrates that can be coated with the antimicrobial coating composition of the present invention are surfaces made of plastic, wood, concrete, stone, polycarbonate, plexiglass, PVC, forex latex, ceramics and the like. Examples of textile substrates that can be coated with the dispersion according to the present invention are NWF, and all textile materials that are intended in the art to be coated.

[0288] The coating composition according to the invention can also be applied to previously coated substrates, for example with varnishes, paints, lacquers and other types of coatings.

[0289] The antimicrobial efficacy of the compositions according to the present invention can be measured in terms of the reduction in the total number of living microbes in contact with the coating.

[0290] For the purposes of the present invention, the antibacterial efficacy can be determined, for example, by means of the ASTM E2180-18 test, even if this is not binding for the purposes of the present invention. in general, the coating compositions of the present invention can be used against potentially pathogenic microorganisms that are present in the environment.

[0291] Microorganisms against which the antimicrobial coating composition is effective include fungi, algae, bacteria and viruses. Examples of fungi are: Aspergillus niger and Penicillium funiculosum. Examples of bacteria are: Gordonia amicalis, Microbacterium hydrocarbonoxidans , Pseudomonas taiwanensis, Pseudomonas resinovorans and Escherichia coll. Further pathogenic bacteria on which the coating compositions of the present invention may be effective are: Listeria monocytogenes, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhimurium, Streptococcus mutans, Staphylococcus epidermidis, Vibrio harveyi and Enterococcus faecalis .

[0292] The coating compositions are also effective against viruses .

[0293] Viruses are small infectious agents (front 0.02 pm up to a maximum of 1 um) consisting of biological material that are unable to live or reproduce autonomously except from within a host cell whose functional mechanisms they exploit. Examples of viruses are: Coronavirus, in particular, the Sars~Cov2 virus.

[0294] For the purposes of the present invention, the antiviral efficacy of the coating compositions can be determined for example as indicated by the ISO 21702:2019 standard "Measurement of antiviral activity on plastics and other non-porous surface", even if this is not binding for the purposes of the present invention.

[0295] Some illustrative but not limiting examples of the present invention follow.

[0296] EXAMPLES

[0297] MATER1ALS - PVP K~30: marketed by Sigma Aldrich and having a weight average molecular weight around 40,000 daltons;

[0298] - PVP K-10: marketed by Sigma Aldrich and having a weight average molecular weight around 10,000 daltons;

[0299] - HSAG Nano 27 graphite: marketed by Asbury Carbons and having a surface area of approximately 250 m2 / g, lateral dimensions of the graphitic layers of approximately 300-400nm, number of stacked graphene layers of approximately 35 and density of 2.26 g / cm3;

[0300] - "Soprophor® BSU" (dispersant): tristyrylphenol ethoxylate marketed by Solvay;

[0301] - "BTC50E": aqueous mixture of benzalkonium chloride (50% by weight) (antimicrobial agent) named and marketed by Stephan;

[0302] ■■■ BAG (100% benzalkonium chloride) (antimicrobial agent) marketed by Sigma Aldrich.

[0303] ■■■ PDADMAC: poly diallyl dimethyl ammonium chloride having an average molecular weight (Mw) of 200,000-350,000, sold by Sigma Aldrich in the form of an aqueous solution at 20% by weight;

[0304] - "Moussex 9157 SE": antifoam agent marketed by Synthron;

[0305] - Metolat 392": water-soluble polymer dispersant (olefin copolymer in water with an anionic character) marketed by Munzing Chemie; ~ Chitosan: marketed by Sigma Aldrich and having a weight average molecular weight (Mw) of approximately 250,000 Da;

[0306] - PEG 400: stabilizer (water-soluble polymer) marketed by Sigma Aldrich and having a number average molecular weight (Mn) of approximately 400 Daltons;

[0307] - Pluronic PE 10550: polyalkylene glycol marketed by BASF;

[0308] - EXOdis PC416 (90% aqueous solution): tristyrylphenol ethoxylate (dispersant) marketed by PCC Group;

[0309] - ROKAnol-TSPl6 (100% polymer): tristyrylphenol ethoxylate-based dispersant marketed by PCC Group;

[0310] - "Rokolub 60-D-150": water-soluble polyalkylene glycol marketed by PCC Group;

[0311] - Polyvinyl alcohol (PVA): marketed by Sigma Aldrich and having a weight average molecular weight of approximately 67,000 Daltons;

[0312] - AMP: 2-amino-2 methyl-l-propanol, as acidity regulator

[0313] (commercial product).

[0314] CHARACTERISATION AND ANALYSIS METHODS

[0315] - Antibacterial efficacy: ASTM E2180-18

[0316] - TSI (Turbiscan Stability Index) was measured on dispersions maintained at 30°C and ambient P for at least three days (measurement after 3 days) using the Turbiscan Tower instrument. UV-visible analysis to determine the concentration of effectively dispersed nano-graphite (quantitative analysis) with an indication of the degree of exfoliation (qualitative analysis)

[0317] UV-visible absorption analysis was conducted using the Perkin Elmer spectrophotometer, model 750-S, on dispersion samples loaded in suprasilicate quartz cells with optical paths of 0.2 and 0.1 cm.

[0318] The acquisition parameters for electronic absorption spectra are: spectral range = 190-850 nm; spectral resolution = 0.5 nm.

[0319] The concentration of the dispersed nano-graphite was obtained by detecting the absorption at 660 nm due to the graphite present in the dispersion samples in accordance with the literature (Mustafa Lotya, Y. Hernandez et al., "Liquid Phase Production of Graphene by Exfoliation of Graphite in Surfactant / Water Solution", The Journal of the American Chemical Soc1ety, 2009, 131, 3611-3620).

[0320] The quantification of this concentration was obtained by constructing a graphite concentration (Cg)- absorbance (A) calibration curve measured at A=660nm according to Lambert-Beer's law A=aCgl with l=length of optical path. This calibration curve was linear in the range of 0-2% mass / mass (R2=0.99), and yielded the absorption coefficient value a ~ 1256 L g-1 m-1, in good agreement with the literature value of the above-mentioned article, a 1390 L g-1 m-1.

[0321] At the end of the preparation process and at subsequent predetermined times, micro-samples of approximately 0.3 cc taken at various times from the surface layer of a 40 cc macro-sample, taken at time 0 after the dispersion to be analysed had been obtained, were analysed and stored in a fixed, vertical position to allow any decanting to take place without interference (height of the macro-sample bottle::::10 cm).

[0322] The micro-sample is diluted 1 to 10 in distilled water and analysed immediately.

[0323] As time progresses, the natural settling process of the macro-sample causes the concentration of nano-graphite in the surface layer of the macro-sample, i.e. the dispersed nano-graphite, to decrease. Knowing the absorbance value of the diluted micro-sample under investigation, it is possible to trace the corresponding concentration of exfoliated graphite on the calibration curve. This gives the concentration of the dispersed nano-graphite. In addition to the quantitative information on the concentration of dispersed nano-graphite, the UV spectrum provides an indication of the degree of exfoliation of the material. The shape of the absorption curve varies with the stacking of the nano-graphite sheets (reference: C. Backes et al., "Spectroscopic metrics allow in situ measurement of mean size and thickness of liquid-exfoliated few-layer graphene nanosheets", Nanoscale, 2016, 8, 4311-4323).

[0324] In accordance with the literature, this degree of exfoliation was assessed by means of the spectral parameter SP (Stacking Parameter)-Absorbance measured at 550 nm / Absorbance measured at 325 nm - A (550 nm) / A(325 nm), which increases with increasing stacking.

[0325] EXAMPLES 1-22 OF PREPARING NANO-GRAPHITE DISPERSIONS

[0326] EXAMPLES 1-5: Aqueous dispersions containing BAC

[0327] Example 1: dispersion with exfoliant (PVP K-30), nano- graphite / PVP K-30 ratio—2.5 and soprophor dispersant (0.3%) added in 2 aliquots

[0328] In a cylindrical reactor with a volume of 1700 mL and a height of 16 cm with a diameter of 11 cm, demineralized water (767 g) and PVP K-30 (8 g) are initially loaded as an exfoliation adjuvant. Next, the Silverson mixer is immersed in the reactor, with the mixer head at a distance from the bottom,of the reactor and the rotor body slightly off-centre with respect to the vertical axis of the reactor, as is conventionally known in the art of using Silverson mixers. In the present example and the following ones using the same reactor, the distance of the mixer head from the bottom of the reactor is about 3 cm and the rotor body is 1.5 cm off- centre with respect to the centre of the reactor.

[0329] Once the mixer is set to a speed of 6000 rpm, 20 g of Nano 27 graphite is added, under agitation while keeping the speed constant for about 30 minutes, at an autogenous temperature not exceeding 70°C.

[0330] After this period, a dispersant is fed in the form of a previously prepared aqueous solution (40g) consisting of water (39 g), and tristyrylphenol ethoxylate "Soprophor" (1 g).

[0331] The resulting mixture is constantly stirred under the same conditions for approximately 60 min. After this period, an antimicrobial agent is added by means of a peristaltic pump (8 mL / min.) in the form of a pre-mixed aqueous solution consisting of water (100 g) and aqueous mixture (40 g) "BTC50E" consisting of water (50% by weight) - benzalkonium chloride (BAC) (50% by weight). During this step, an antifoam agent (2.00 g) called "Moussex 9157 SE" is co-fed to prevent foaming. At the end of this period, another aliquot of dispersant is added by means of a peristaltic pump (8 mL / min) in the form of a pre-mixed aqueous solution (32 g) consisting of water (30 g), and polymeric tristyrylphenol ethoxylate dispersant "Soprophor" (2 gj.

[0332] The overall mixture (slurry) is kept at 6000 rpm for a further 60 min.

[0333] The total mixing time at 6000 rpm of the entire dispersion is not continued beyond four hours. it has been noted that prolonged mixing times, beyond four hours, are not necessary to obtain a stable homogeneous dispersion in accordance with the invention.

[0334] This results in a homogeneous dispersion "with a TSI index of 0.5.

[0335] The dispersion was prepared to obtain the following nominal composition in % by weight:

[0336] Water 94.75%

[0337] PVP K30 0.79%

[0338] Nano graphite 1.98%

[0339] Trisi.yry1pnenoi etnoxyiate 0.3u%

[0340] BAG 1.98%

[0341] Antifoam 0.20% with a graphite / exfoliant weight ratio of 2.5. This product is therefore stable enough to be used at a later stage as a graphene-containing additive for the preparation of paints and / or enamels with antibacterial and antiviral properties due to the presence of nano-graphite and BAG.

[0342] Example 2: dispersion with exfoliant (PVP K-30), nano- graph!te / PVP K-30 ratio-2.5 and soprophor dispersant (0.2%) added in a single aliquot, with UV-VIS measurement

[0343] In the same reactor used in Example 1, demineralized water (780 g) and PVP K30 (8 g) are loaded as an exfoliation adjuvant.

[0344] Next, the Silverson mixer is immersed under the same conditions and in the same way as in Example 1.

[0345] Once the mixer is set to a speed of 6000 rpm, 20 g of Nano 27 graphite is added, under agitation while keeping the speed constant for about 30 minutes, at an autogenous temperature not exceeding 70°C.

[0346] The resulting mixture is constantly stirred under the same conditions for about 90 min.

[0347] At the end of this period, the antimicrobial agent is added by means of a peristaltic pump (8 mL / min.) in the form of a pre-mixed aqueous solution consisting of water (100 g) and aqueous mixture (40 g) "BTC50E" consisting of water (50% by weight) - benzalkonium chloride (50% by weight). During this step, an anti foam agent (2.00 g) called

[0348] "Moussex 9157 SE" is co-ted to prevent foaming.

[0349] The resulting mixture is stirred tor a further 60 min at

[0350] 6000 rpm.

[0351] At the end of this period, a dispersant is added by means ot a peristaltic pump (8 mL / min) in the form of a pre-mixed aqueous solution consisting of water (48 g) , and pol ynteric tri styrylphenol ethoxylate dispersant

[0352] "Soprophor" (2 g) .

[0353] The total mixing time at 6000 rpm of the entire dispersion is not continued beyond four hours, similar to Example 1.

[0354] The dispersion was prepared to obtain the following composition in % by weight:

[0355] Water 94.80%

[0356] PVP K30 0.80%

[0357] Nano graphite 2.00%

[0358] Tristyrylphenol ethoxylate 0.20%

[0359] BAG 2.00%

[0360] Anti foam 0.20%

[0361] A homogeneous dispersion is obtained with a concentration of exfoliated, allotrope dispersed, in solution equal to 70% by weight (at. t ime zero ) compared to the i n i t. i a 1 concentration of allotrope not yet exfoliated, as measured by UV-VTS. This also res nits in Si TSi index of 0.5 and a graphite / exf oliant weight ratio of 2.5.

[0362] This product is therefore sufficiently stable to be used

[0363] 1 a t e r a. s a graphene-containing additive in the preparation of antibacterial paints and / or enamels.

[0364] Comparative 1 : dispersion in the absence of exf oliant, in the presence of Soprophor dispersant (0.9%) added in two aliquots.

[0365] In the same reactor used in Example 1, 874.8 g of demineralized water is loaded.

[0366] Next, the Silverson mixer is immersed under the same conditions and in the same way as in Example 1.

[0367] Once the mixer has been set to a speed of 6000 rpm, 24 g of Nano 27 graphite is added, under constant stirring for about 30 minutes, at an autogenous temperature not exceeding

[0368] 70 ° C .

[0369] At the end of this period, dispersant is added by means of a peristaltic pump (8 mL / min) in the form of a pre-mixed aqueous solution consisting of water (48 g) , and polymeric t r 1 s t y r y 1 p h e n o 1 ethoxylate dispersant

[0370] "Soprophor (5.4 g) .

[0371] The resulting slurry is constantly stirred for a. further

[0372] 30 min followed by the addition of the antimicrobial agent in the form of a pre-mixed aqueous solution consisting of water (168 g) and benzalkonium chloride (24g).

[0373] During this step, an antifoam agent (2.40 g) called "Moussex 9157 SE" is co-fed to prevent foaming.

[0374] The resulting mixture is stirred for a further 60 min at 6000 rpm .

[0375] After this period, a further aliquot of dispersant is added by means of the peristaltic pump in the form of a premized aqueous solution consisting of water (48 g), and tristyrylphenol ethoxylate "Soprophor" (5.4 g).

[0376] The entire reaction slurry is kept at 6000 rpm for a further 30 min.

[0377] The total mixing time at 6000 rpm of the entire dispersion is not continued beyond four hours, similar to Example 1.

[0378] The dispersion was prepared to obtain the following composition (in % by weight):

[0379] Water 94.90%

[0380] Nano graphite

[0381] Tristyrylphenol ethoxylate 0.9

[0382] BAG

[0383] Antifoam

[0384] The result is a dispersion with a TSI index greater than

[0385] 10, with re-aggregation and phase separation evident to the The dispersion thus obtained is not sufficiently stable over time to be used later as an additive in the preparation of paints and / or enamels.

[0386] Example 3: dispersion with exfoliating premix (PVT? K-30)~ nano-graphite, nano-graphite / PVP K30 ratio=5 and dispersant metolat 392 (0.2%) added in a single aliquot

[0387] The same reactor as in Example 1 is initially loaded with demineralized water (924 g), and PVP K30 (4.4 g) as an exfoliation adjuvant.

[0388] Next, the Silverson mixer is immersed in the reactor, as described in Example 1.

[0389] Once the mixer has been set to a pre-mixing speed of 3000 rpm, 22 g of Nano 27 graphite is added, under such agitation while keeping the speed constant for 30 minutes. This premix phase between the exfoliating agent (PVP) and Nano 27 graphite favours and speeds up the establishment of interactions (e.g. adsorption) between the exfoliating agent (PVP) and the substrate to be exfoliated (Nano 27 graphite).

[0390] After the 30 minutes at 3000 rpm, the Silverson rpm is increased to 6000 rpm and the mixture (slurry) is kept under these stirring conditions for about 90 minutes, at autogenous temperatures not exceeding 70°C.

[0391] At the end of this period, an antimicrobial agent is added by means of a peristaltic pump (8 mL / min.) in the form of a previously prepared aqueous solution consisting of water (44 g) ana aqueous mixture (44 g) "BTC50E" consisting of water (50% by weight) - benzalkonium chloride (50% by weight).

[0392] During this step, an antifoam agent (2.20 g) called "Moussex 9157 SE" is co-fed to reduce foaming.

[0393] The resulting mixture is stirred for a further 60 min at 6000 rpm .

[0394] At the end of this period, a dispersant is added by means of a peristaltic pump (8 mL / min) in the form of a pre-mixed aqueous solution consisting of water (55 g), and water-soluble polymeric dispersant called "Metolat 392" (4.40 g).

[0395] The overall mixture (slurry) is kept at 6000 rpm for a further 60 min.

[0396] The total mixing time at 6000 rpm of the entire dispersion is not continued beyond four hours, similar to Example 1.

[0397] The dispersion was prepared to obtain the following composition in % weight:

[0398] Water 95.00%

[0399] PVP K30 0.40%

[0400] Nano graphite 2.00%

[0401] BAG 2.00%;

[0402] Dispersant Metolat 392 0.40%

[0403] Antifoam 0.20% This results in a homogeneous dispersion with a TSI index of 0.4 and a graphite / exfoliant ratio of 5.

[0404] This product is therefore sufficiently stable to be used later as a graphene-containing additive in the preparation of paints and / or enamels.

[0405] Example 3bis

[0406] Example 3 was repeated keeping the quantities of the components constant, but first mixing all the components except Nano 27 graphite (demineralized water, PVP K30, BTC50E, defoamer "Moussex 951 SE" and dispersant "Metolat 392") at 6000 rpm for 30 minutes, then adding Nano 27 graphite once the 30 minutes of stirring had elapsed.

[0407] The resulting slurry is then mixed with Silverson at 6000 rpm for up to four hours.

[0408] This process was also found to lead to homogeneous dispersions with a TSI value acceptable for the purposes of the present invention (TSI:::1).

[0409] Comparative 2: exfoliant-~free dispersion with dispersant metolat 392 (1%) added in two aliquots.

[0410] Example 3 of the invention was repeated, but without adding any exfoliation adjuvant compounds in accordance with the invention, using different amounts of ingredients than in Example 3 and adding the dispersant in two aliquots instead of one aliquot. Using the same reactor as in Example 1, demineralized water (838 g) and 2 g water-soluble polymeric dispersant "Metolat 392" are initially loaded.

[0411] Next, the Silverson mixer is immersed in the reactor under the conditions and in the manner described in Example 1.

[0412] Once the mixer is set to a speed of 6000 rpm, 20 g of Nano 27 graphite is added, under agitation while keeping the speed constant for about 30 minutes, at an autogenous temperature not exceeding 70° C.

[0413] At the end of this period, an antimicrobial agent is added by means of a peristaltic pump (8 mL / min) in the form of a pre-mixed aqueous solution consisting of water (40 g) and aqueous mixture (40 g) "BTC50E" consisting of water (50% by weight) - benzalkonium chloride (50% by weight).

[0414] During this step, an antifoam agent (2.00 g) called "Moussex 9157 SE" is co-fed to reduce foaming.

[0415] Once the addition of antimicrobial and antifoam agents has been completed, a second aliquot of dispersant is added by means of a peristaltic pump (8 mL / min.) in the form of a pre-mixed aqueous solution consisting of water (50 g), and water-soluble polymer dispersant (8.0 g) called "Metolat

[0416] 392" The overall mixture (slurry) is kept at 6000 rpm for a further 60 min.

[0417] The dispersion was prepared to obtain the following composition in % weight:

[0418] Water 94.80%

[0419] Nano graphite 2.00%

[0420] BAG 2.00%

[0421] Dispersant Metolat 392 1.00%

[0422] Antifoam 0.20%

[0423] The result is a dispersion with a TSI index greater than

[0424] 10 and therefore not sufficiently stable to be subsequently used as a graphene-containing additive in the preparation of antibacterial paints and / or enamels.

[0425] Example 4: dispersion with exfoliating premix (PVP K-10)- nano-graphite, nano-graphite / PVP K-10 ratio™5 and dispersant metolat 392 (0.2%) added in 1 step

[0426] Example 3 of the invention was repeated but using PVP K10 instead of PVP K-30 as an exfoliation adjuvant, using the same quantities of dispersion components as in Example 3. This results in a homogeneous dispersion with a TSI index of 0.4 and a graphite / exfoliant weight ratio of 5.

[0427] This product is therefore stable enough to be used later as an antibacterial / antiviral additive in the preparation of paints and / or varnishes. Example 5: aqueous dispersion containing chitosan as exfoliant, nano-graphite / exfoliant ratio—1 and PEG 400 as stabiliser

[0428] In the same reactor used in example 1, demineralized water (1239 g) and glacial acetic acid (2.8 g) are loaded.

[0429] Next, the Silverson mixer is immersed in the same manner and conditions as in Example 1.

[0430] Once the mixer is set to a speed of 6000 rpm, 14 g of medium molecular weight chitosan is added as an exfoliation adjuvant.

[0431] This process of solubilizing chitosan in Silverson mixers is particularly fast and efficient without requiring any assistance from the external temperature.

[0432] Once the chitosan premix phase is complete, 14 g of Nano 27 graphite is added, again while stirring at 6000 rpm, keeping the speed constant for 60 minutes.

[0433] At the end of this period, an antimicrobial agent is added by means of a peristaltic pump (8 mL / min) in the form of a pre-mixed aqueous solution consisting of water (70 g) and benzalkonium chloride (4.20 g).

[0434] The resulting mixture is stirred for a further 60 min at

[0435] 6000 rpm . At the end of this period, a stabilizing agent is added by means of a peristaltic pump (8 mL / min) in the form of a pre-mixed aqueous solution consisting of water (42 g) , and water-soluble polymeric stabilizing' agent called "PEG 400"

[0436] (14 g) .

[0437] The overall mixture is constantly stirred at 6000 rpm for

[0438] 60 minutes.

[0439] The dispersion was prepared to obtain the fol lowing composition in % weight

[0440] Water 96.50%

[0441] Glacial acetic acid 0.20%

[0442] Chitosan 1.00%

[0443] Nano graphite 1.00%

[0444] BAG 0.30%

[0445] PEG 400 1.00%

[0446] This results in a homogeneous dispersion with a TSI index of 0.5 and a grapnite / exf oliant weight ratio of 1.

[0447] This product is therefore sufficiently stable to be used f o r the preparation of protective non-woven fabric (NWF) systems coated with such a dispersion having' antibacterial and. antiviral characteristics.

[0448] Comparative 3: dispersion in the absence of exfoliant and dispersant and in the presence of stabilizer (PEG 400) In the same reactor used in Example 1, demineralized water (1359.8 g), polyethylene glycol (Mn:::400; 11.2 g) and benzalkonium chloride (14.49 g) are loaded.

[0449] Next, the Silverson mixer is immersed in the same manner and conditions as in Example 1.

[0450] Once the mixer is set to a speed of 5000 rpm, 14.5 g of Nano 27 graphite is added while stirring and keeping the speed constant for about three hours at an autogenous temperature not exceeding 60°C.

[0451] The dispersion was prepared to obtain the following composition in % weight:

[0452] Water 97.12%

[0453] Nano graphite 1.04%

[0454] BAG 1.04%

[0455] PEG 400 0.80%

[0456] The resulting dispersion has a TSI index greater than 10 and is therefore not sufficiently stable to be used later in the preparation of paints and / or enamels.

[0457] Comparative 4: dispersion in the absence of dispersant, in the presence of stabilizer (PEG 400) and using a mixture of BAG and poly diallyl dimethyl ammonium chloride (PDADMAC) as antimicrobial.

[0458] In the same reactor used in Example 1, 840 g of demineralized water is loaded. Next, the Silverson mixer is immersed in the same manner and conditions as in Example 1.

[0459] Once the mixer is set to a speed of 5000 rpm, 70 g of Nano 27 graphite is added while stirring and keeping the speed constant for about three hours at an autogenous temperature not exceeding 70°C.

[0460] At the end of this period, a mixture is added by means of a peristaltic pump (8 mL / min) in the form of an aqueous solution consisting of water (210 g), poly diallyl dimethyl ammonium chloride (solution 20% w / w; 140 g), benzalkonium chloride (70 g).

[0461] The resulting slurry is constantly stirred for a further 60 min, followed by the addition of a stabilizer in the form of a pre-mixed aqueous solution consisting of water (14 g) and polyethylene glycol (Mn = 400; 56 g).

[0462] Once the additions are finished, stirring is maintained for a further hour.

[0463] The dispersion was prepared to obtain the following composition in % weight:

[0464] Water 84.00%

[0465] Nano graphite 5.00%

[0466] Poly diallyl dimethyl ammonium chloride 2.00% BAG 5.00%

[0467] PEG 400 4.00%

[0468] This results in a dispersion with a TSI index greater than 10 and is therefore not sufficiently stable to be used later in the preparation of paints and / or enamels or for direct application on textile substrates.

[0469] Comparative 5: dispersion in the absence of exfoliant and dispersant, in the presence of stabilizer (PEG 400) and using BAC as antimicrobial in basic environment.

[0470] In the same reactor as in Example 1 the following are loaded respectively: demineralized water (1363.46 g), 50 % w / w caustic soda solution (0.14 g), polyethylene glycol (Mn = 400; 11.20 g) benzalkonium chloride (11.20 g).

[0471] Next, the Silverson mixer is immersed in the reactor under the conditions and in the manner described in Example 1.

[0472] Once the mixer has been set to a speed of 5000 rpm, 14 g of Nano 27 graphite is added, under constant stirring for about three hours, at an autogenous temperature not exceeding 60°C.

[0473] The dispersion was prepared to obtain the following composition in % weight:

[0474] Water 97.37%;

[0475] NaOH 0.005%

[0476] PEG 400 0.81% BAG 0.81%

[0477] Nano graphite 1.01%

[0478] The resulting dispersion has an TSI index value greater than 10. This shows that even increasing the pH of the dispersion frontacidic (pH of the dispersions of comparative examples 1,2,3, in the absence of exfoliant) to basic does not result in the dispersion achieving stability.

[0479] Comparative 6: dispersion in the absence of exfoliant and dispersant, in the presence of stabilizer (PVA)

[0480] Demineralized water (965.9 g) is loaded into the same reactor as in Example 1.

[0481] Next, the Silverson mixer is immersed in the reactor under the conditions and in the manner described in Example 1.

[0482] Once the mixer is set to a speed of 5000 rpm, 13 g of Nano 27 graphite is added.

[0483] The entire slurry is stirred constantly (5000 rpm) for about 30 minutes, at an autogenous temperature not exceeding 70°C.

[0484] At the end of this period, a pre-mixed aqueous solution consisting of water (91.65 g), benzalkonium chloride (13 g) and defoamer "Moussex 9157 SE" (1.3 g) is added by means of a peristaltic pump (8 mL / min.).

[0485] The resulting slurry is constantly stirred for a further 60 min, followed by the addition of a second pre-mixed aqueous solution consisting of water (208 g) , polyvinylalcohol (PVA) (6.5 g) ,

[0486] "Moussex 915 / SE" defoamer (1.3 g) .

[0487] The dispersion was prepared to obtain the following composition in % weight:

[0488] Water 97.30%

[0489] Nano-grap h.11 e 1.00%

[0490] BAG 1.00%

[0491] Ant if oam 0.20%

[0492] PVA 0.50%

[0493] The resulting dispersion has a TSI value greater than 10 and is therefore not sufficiently stable to be used later as a graphene-containing additive.

[0494] EXAMPLES 6-11: NANO-GRAPHITE DISPERSIONS IN ORGANIC SOLVENT

[0495] WITH RAC AND WITHOUT RAC

[0496] Example 6: solvent dispersion with exfoliating agent (PVP

[0497] K-30) , nano-graphi te / PVP K-30 ratio™! stabilizer (PEG 400) and BAG

[0498] The same rector as in Example 1 is initially loaded with

[0499] 2 -propanol (951.05 g) and PVP K-30 (11.5 g ) .

[0500] Next , the Silverson mixer is immersed in the reactor, similarly to what was described, in Example 1.

[0501] Once the mixer is set to a speed of 3000 rpm, 11.50 g of

[0502] Nano 27 graphite is added, under agitation while keeping' the speed constant for 30 minutes. This premix phase between the exfoliating agent (PVP) and Nano 27 graphite is advantageous in that it promotes and speeds up the interaction (adsorption) between the exfoliating agent (PVP) and the substrate to be exfoliated (Nano 27 graphite).

[0503] Similar to some of the previous examples, after the 30 minutes, the Silverson rpm is increased to a value of 6000 rpm, and the mixture (slurry) is kept under these stirring conditions for about 60 minutes, at autogenous temperatures not exceeding 50°C.

[0504] The temperature is maintained at the indicated threshold value so as to avoid boiling of the solvent. The reactor is cooled by water and dry ice contained in a vessel into which the reactor is immersed before starting the preparation.

[0505] At the end of this period, an antimicrobial agent is added by means of a peristaltic pump (8 mL / min) in the form of a pre-mixed alcohol solution consisting of

[0506] 2-propanol (80.5 g), and benzalkonium chloride (5.75 g).

[0507] No foaming occurs during this phase.

[0508] The resulting mixture is stirred for a further 60 min at 6000 rpm .

[0509] At the end of this period, a stabilizing agent is added by means of a peristaltic pump (8 mL / min) in the form of a pre-mixed alcohol solution consisting of 2-propanol (80.5 g), and polyethylene glycol designated "PEG - 400" (9.20 g).

[0510] The overall mixture is constantly stirred at 6000 rpm for 60 minutes.

[0511] The total mixing time at 6000 rpm of the entire dispersion is not continued beyond three hours, similar to the previous examples.

[0512] The dispersion was prepared to obtain the following composition in % weight:

[0513] 2-Propanol 96.70%

[0514] PVP K30 1.00%

[0515] Nano graphite 1.00%

[0516] BAG 0.50%

[0517] PEG 400 0.80%

[0518] This results in a homogeneous dispersion with a TSi index of 0.4 and a graphite / exfoliant weight ratio of 1.

[0519] This product is therefore sufficiently stable to be used later as a graphene-containing additive.

[0520] Example 7: solvent dispersion with exfoliating agent (PVP

[0521] K-30), nano-graphite / PVP K-30 ratio~l and dispersant

[0522] (tristyrylphenol ethoxylate) and RAC

[0523] Tne same reactor as in Example i i.s initially loacied with 2-propanol (909.7 g), and PVP K30 (11.0 g).

[0524] Next, the Silverson mixer is immersed in the reactor, similarly to what was described in Example 1. Once the mixer is set to a speed of 3000 rpia, 11.0 g of Nano 27 graphite is added under agitation while keeping the stirring speed constant for 30 minutes.

[0525] Then, after the 30 minutes, the speed of the Silverson mixer is increased to a value of 6000 rpm and the mixture (slurry) is kept in these stirring conditions for about 60 minutes, at an autogenous temperature not exceeding 50° C, similar to Example 6.

[0526] At the end of this period, a first aliquot of dispersant is added by means of a peristaltic pump (8 mL / min.) in the form of a pre-mixed alcoholic solution consisting of 2-propanol (38.5 g) and polymeric dispersant based on tristyrylphenol ethoxylate known as EXOdis PC416 (4.40 g).

[0527] The resulting mixture is constantly stirred for 30 min at 6000 rpm .

[0528] At the end of this period, an antimicrobial agent is added by means of a peristaltic pump (8 mL / min.) in the form of a pre-mixed alcohol solution consisting of 2-propanol (77 g) and benzalkonium chloride (5.50 g).

[0529] No foaming occurs during this phase.

[0530] The resulting mixture is stirred for a further 60 min at

[0531] 6000 rpm . At the end of this period, a further portion of dispersant is added by means of a peristaltic pump (8 mL / min.) in the form of a pre-mixed alcohol solution consisting of

[0532] 2-propanol (38.5 g), and polymeric dispersant based on tristyrylphenol ethoxylate called EXOdis PC416 (4.40 g).

[0533] The overall mixture is constantly stirred under these conditions for 60 minutes.

[0534] The total mixing time at 6000 rpm of the entire dispersion is not continued beyond three hours, similar to the previous examples.

[0535] The dispersion was prepared to obtain the following composition in % weight:

[0536] 2-Propane1 96.70%

[0537] PVP K30 1.00%

[0538] Nano graphite 1.00%

[0539] BAG 0.50%

[0540] Tristyrylphenol ethoxylate PC 416 0.80%

[0541] This results in a homogeneous dispersion with a TS1 index of 0.4 and a graphite / exfoliant weight ratio of 1.

[0542] This product is therefore stable enough to be used later as a graphene-containing additive.

[0543] Example 8:solvent dispersion with exfoliating agent (PVP K~30), nano-graphite / PVP K~30 ratio=l with dispersant

[0544] (tristyrylphenol ethoxylate) and BAC (aqueous solution) The process of Example 7 was repeated until graphite was added, using the same quantities of graphite, 2-propanol and PVP K30.

[0545] A first aliquot of dispersant is then added by means of a peristaltic pump (8 mL / minj in the form of a pre-mixed alcohol solution consisting of

[0546] 2-propanol (38.5 g) and polymeric dispersant based on tristyrylphenol ethoxylate known as ROKAno1-TSPl6 (2.20 g).

[0547] At the end of the additions, the resulting mix is stirred for 30 min at 6000 rpm.

[0548] At the end of this period, an antimicrobial compound is added by means of a peristaltic pump (8 mL / min) in the form of a pre-mixed alcohol solution consisting of

[0549] 2-propanol (66 g) and aqueous solution known as "BTC50E" (11 g) consisting of water (50 wt. %) and benzalkonium chloride (50 wt. %).

[0550] No foaming occurs during this phase.

[0551] The resulting mixture is stirred for a further 60 min at 6000 rpm .

[0552] At the end of this period, a second aliquot of dispersant is added by means of a peristaltic pump (8 mL / min.) in the form of a pre-mixed alcohol solution consisting of

[0553] 2-propanol (44 g), and polymeric dispersant based on tristyrylphenol ethoxylate known as ROKAnol-TSPl6 (6.60 g).

[0554] The overall mixture is constantly stirred at 6000 rpm for 60 minutes.

[0555] The total mixing time at 6000 rpm of the entire dispersion is not continued beyond three hours, similar to the previous examples.

[0556] The dispersion was prepared to obtain the following composition in % weight:

[0557] 2-Propane1 96.20%

[0558] PVP K30 1.00%

[0559] Nano graphite 1.00%

[0560] BAG 0.50%

[0561] Tristyrylphenol ethoxylate TSP 16 0.80%

[0562] Water 0.50%

[0563] This results in a homogeneous dispersion "with a TSI index jf 0.4 and a graphite exfoliant weight ratio of 1.

[0564] This product is therefore sufficiently stable to be used later as a graphene-containing additive.

[0565] Example 9: solvent dispersion with exfoliant PVP K-30, nano-graphite / PVP K-30 ratio—1, with dispersant Metolat 392 and BAC (aqueous solution)

[0566] The same reactor as in Example 1 is initially loaded with

[0567] 2-propanol (930.6 g)fand

[0568] PVP K30 (11,0 g). Next, the Silverson mixer is immersed in the reactor, similarly to what was described in Example 1.

[0569] Once the mixer is set to a speed of 3000 rpm, 11.0 g of Nano 27 graphite is added.

[0570] This premix phase between exfoliating agent (PVP) and Nano 27 graphite is advantageous in facilitating and speeding up the interaction (adsorption) between the exfoliating agent (PVP) and the substrate to be exfoliated (Nano 27 graphite).

[0571] The premix phase is maintained for 30 minutes, then the Silverson speed is increased to a value of 6000 rpm.

[0572] The entire slurry is kept under the above conditions for about 60 minutes at an autogenous temperature not exceeding 50° C.

[0573] The temperature is maintained at the indicated threshold value as the reactor is immersed in a vessel cooled with water and dry ice.

[0574] At the end of this period, a pre-mixed alcohol solution is added by means of a peristaltic pump (8 mL / min.), consisting of

[0575] 2-propanol (66 g) and solution called "BTC50E" (11 g) consisting of water (50 %) and benzalkonium chloride (50 %).

[0576] No foaming occurs during this phase.

[0577] The resulting mixture is stirred for a further 60 min at

[0578] 6000 rpm . At the end of this period, a peristaltic pump (8 mL / min.) is used to add: a pre-mixed alcohol solution consisting of 2-propanol (66 g), and polymeric dispersant called "Metolat 392" (4.40 g).

[0579] The total mixing time at 6000 rpm of the entire dispersion is not continued beyond three hours.

[0580] The dispersion was prepared to obtain the following composition in % weight:

[0581] 2-Propane1 96.60%

[0582] PVP K30 1.00%

[0583] Nano graphite 1.00%

[0584] BAG 0.50%

[0585] Metolat 392 0.40%

[0586] Water 0.50%

[0587] This results in a homogeneous dispersion with a TSI index of 0.4 and a graphite / exfoliant weight ratio of 1.

[0588] This product can then later be used as a graphenecontaining additive.

[0589] Example 10: solvent dispersion with exfoliant PVP K-10fnano-graphite / PVP K-10 ratio—1, with dispersant Metolat 392 and BAC (aqueous solution)

[0590] The same reactor as in Example 1 is initially loaded with 2-propanol (930.6 g) and PVP K-10 (11.0 g). Next, the Silverson mixer is immersed in the reactor, similarly to what was described in Example 1.

[0591] Once the mixer is set to a speed of 3000 rpm, 11.0 g of Nano 27 graphite is added, under agitation while keeping the speed constant for 30 minutes.

[0592] Similarly to some previous examples, after the 30 minutes, the Silverson rpm is increased to a value of 6000 rpm and the mixture (slurry) is kept in this condition for about 60 minutes, at autogenous temperature values not exceeding 50° C, similar to previous examples of organic solvent-based dispersions (e.g. 6, 7, 8 and 9).

[0593] At the end of this period, an antimicrobial agent is added by means of a peristaltic pump (8 mL / min) in the form of a pre-mixed alcohol solution consisting of

[0594] 2-propanol (66 g) and aqueous solution known as "BTC50E" (11 g) consisting of water (50 wt. %) and benzalkonium chloride (50 wt. %).

[0595] No foaming occurs during this phase.

[0596] The resulting mixture is stirred for a further 60 min at 6000 rpm .

[0597] At the end of this period, a dispersant in the form of a pre-mixed alcohol solution is added by means of a peristaltic pump (8 mu / min), consisting of

[0598] 2—propano.1 (66 g), and oolymeric dispersant called ''Metolat 392" (4.40 g). The overall mixture is maintained at 6000 rpm for 60 minutes.

[0599] The total mixing time at 6000 rpm of the entire dispersion is not continued beyond three hours, similar to the previous examples.

[0600] The dispersion was prepared to obtain the following composition in % weight:

[0601] 2-Propanol 96.60%

[0602] PVP K10 1.00%

[0603] Nano graphite 1.00%

[0604] BAG 0.50%

[0605] Metolat 392 0.40%

[0606] Water 0.50%

[0607] This results in a homogeneous dispersion with a TSI index of 0.4 and a graphite / exfoliant weight ratio of 1.

[0608] This product is therefore stable enough to be used later as a graphene-containing additive.

[0609] Example 11: solvent dispersion with exf'oliant PVP K-30, nano-graphite / PVP K-30 ratio~l, with dispersant (tristyrylphenol ethoxylate) without BAC

[0610] The same reactor as in Example 1 is initially loaded with 2-propanol (979 g), and PVP K30 (13.2 g).

[0611] Next, the Silverson mixer is immersed in the reactor, similarly to what was described in Example 1. Once the mixer is set to a speed of 3000 rpm, 13.2 g of Nano 27 graphite is added under agitation while keeping the stirring speed constant for 30 minutes.

[0612] Then, after the 30 minutes, similar to Example 6, the speed of the Silverson mixer is increased to a value of 6000 rpm and the mixture (slurry) is kept in these stirring conditions for about 60 minutes, at an autogenous temperature not exceeding 50°C, similar to Example 6.

[0613] At the end of this period, the dispersant is added by means of a peristaltic pump (8 mL / min.) in the form of a pre-mixed alcohol solution consisting of 2-propanol (77.0 g) and polymeric dispersant based on tristyrylphenol ethoxylate called "Soprophor ® BSU" (17.60 g).

[0614] The overall mixture is kept under agitation in these conditions for 60 minutes.

[0615] The total mixing time at 6000 rpm of the entire dispersion is not continued beyond three hours, similar to the previous examples.

[0616] The dispersion was prepared to obtain the following composition in % weight:

[0617] 2-Propanol 96%

[0618] PVP K30 1.2%

[0619] Nano graphite 1.2%

[0620] Tristyrylphenol ethoxylate Soprophor 1.6% This results in a homogeneous dispersion with a TSI index of 0.4 and a graphite / exfoliant weight ratio of 1.

[0621] This product is therefore sufficiently stable to be used later as a graphene-containing additive.

[0622] EXAMPLES 12-22: BAG-FREE AQUEOUS DISPERSIONS OF NANOGRAPHITE

[0623] Example 12: aqueous dispersion without dispersant, containing chitosan as exfoliant and a stabilizer with nanographite concentration-0.5 wt.%

[0624] The reactor of Example 1 is initially loaded with demineralized water (1379 g), and glacial acetic acid (1.4 g)•

[0625] Next, the Silverson mixer is immersed in the reactor, similar to Example 1.

[0626] Once the mixer is set to a speed of 6000 rpm, 4.2 g of medium molecular weight chitosan is added as an exfoliation adjuvant.

[0627] Once the chitosan premix phase (exfoliating agent) is completed, again at 6000 rpm, water-soluble polyethylene glycol called "PEG-400" is added (8.4 g) as a stabilizer.

[0628] Once the addition of "PEG-400" is finished, mixing at 6000 rpm is continued for a further 60 min. to promote interactions between "PEG-400" and chitosan. The resulting substrate is suitable for the subsequent role of exfoliating agent for the "Nano 27" graphitic substrate.

[0629] Once the 60 minutes have elapsed, Nano 27 graphite (7 g) is added, again while stirring at 6000 rpm.

[0630] The overall mixture is constantly stirred for a further 60 minutes at 6000 rpm.

[0631] The total mixing time at 6000 rpm of the entire dispersion, once the graphitic substrate has been added, is not continued beyond three hours, similar to the previous examples.

[0632] This results in a homogeneous dispersion with a TSI index of 0.5 and a graphite / exfoliant weight ratio of 1.67.

[0633] The dispersion was prepared to obtain the following composition in % weight:

[0634] WcitGi? 98*50%

[0635] Glacial acetic acid 0.10%

[0636] Chitosan 0.30%

[0637] PEG 400 0.60%

[0638] Nano graphite 0.50%

[0639] This product is therefore stable enough to be used later as a graphene-based additive.

[0640] Example 13: aqueous dispersion with chitosan, stabilizer without dispersant and nano-graphite oonaentration-1% weight Similar to Example 12, demineralized water (1104.2 g) and glacial acetic acid (1.8 g) are initially loaded into the reactor of Example 1.

[0641] Next, the Silverson mixer is immersed in the reactor under the conditions and manner described in Example 1.

[0642] Similar to Example 12, once the mixer is set to a speed of 6000 rpm, 9.6 g of medium molecular weight chitosan is added while stirring as an exfoliation adjuvant.

[0643] Once the chitosan premix phase is complete, nano 27 graphite (12 g) is added, again at 6000 rpm.

[0644] The resulting slurry is constantly stirred for a period of about 90 min.

[0645] At the end of this period, a peristaltic pump (8 mL / min) is used to add a stabilizer in the form of a previously prepared aqueous solution consisting of water (60 g) and polyethylene glycol known as "PEG-400" (12 g).

[0646] Foam formation within the reaction slurry is managed by the addition of defoamer (0.36 gj known as "Moussex 9157 SE".

[0647] The total mixing time at 6000 rpm of the entire dispersion, once the graphitic substrate has been added, is not continued beyond three hours.

[0648] The dispersion was prepared to obtain the following composition in % weight WcitQi? 97 02%

[0649] Glacial acetic acid 0.15%

[0650] Chitosan 0.80%

[0651] PEG 400 1.00%

[0652] Nano graphite 1.00%

[0653] Antifoam 0.03%

[0654] This results in a homogeneous dispersion with a TSI index of 0.5 and a graphite / exfoliant weight ratio of 1.25.

[0655] This product is therefore sufficiently stable to be used later as a graphene-containing additive.

[0656] Example 14: aqueous dispersion with chitosan, different stabilizer (Pluronic PE10500) without dispersant and nanographite concentration~l% weight

[0657] Similarly to Examples 12 and 13, demineralized water (1366.4 g) and glacial acetic acid (2.8 g) are initially loaded into the reactor of Example 1. Once the mixer is set to si speed of 3000 rpm, 11.2 g of medium molecular weight chitosan is added while stirring as an exfoliation adjuvant.

[0658] During this 30~minute phase, the Silverson mixer is increased from 3000 rpm to 6000 rpm to facilitate the mixing of the chitosan in the reaction environment.

[0659] Once the chitosan has dissolved, the Pluronic PE 10500 polyalkylene glycol (5.6 g) is added while stirring constantly at 6000 rpm. This promotes interactions between chitosan and Pluronic PE10550. At the end of this period, Nano 27 graphite (14 g) marketed by Asbury Carbons is added.

[0660] The entire slurry is kept under the above conditions for up to three hours, monitoring to make sure the internal autogenous temperature does not exceed 70° C.

[0661] The dispersion was prepared to obtain the following composition in % weight:

[0662] Water 911.60%

[0663] GJ.acia-i. a.cet.J.c ac1ci 0.20%

[0664] Chitosan 0.80%

[0665] Pluronic PE 10500 0.40%

[0666] Nano graphite 1.00%

[0667] This results in a homogeneous dispersion with a TSi index of 0.4 and a nano-graphite / exfoliant ratio of 1.25.

[0668] This product is therefore stable enough to be used later as a graphene-based additive.

[0669] Example 15: aqueous dispersion with exfoliant combination (chitosan + PVP K-30) without dispersant and stabilizer with nano-graphite concentration=l% weight

[0670] Similar to what is described in Examples 12 and 13 and 14, demineralized water (1366.4 g) and glacial acetic acid (2.8 g) are initially loaded into the reactor of Example 1. Similar to Example 14, once the mixer is set to a speed of 3000 rpm, 11.2 g of medium molecular weight chitosan is added while stirring as an exfoliation adjuvant. During this 30-minute premix step, the Silverson mixer is increased from 3000 rpm to 6000 rpm to facilitate the mixing of the chitosan in the reaction environment.

[0671] Once the chitosan is solubilized, while keeping stirring constant at 6000 rpm, polyvinyl pyrrolidone PVP K30 (5,6 g) is added.

[0672] At the end of this period, Nano 27 graphite (14 g) marketed by Asbury Carbons is added.

[0673] The entire slurry is kept under the above conditions for up to three hours, monitoring to make sure the internal autogenous temperature does not exceed 70°C.

[0674] The dispersion was prepared to obtain the following composition in % weight:

[0675] Water 97.60%

[0676] Glacial acetic acid 0.20%

[0677] Chitosan 0.80%

[0678] PVP K30 0.40%

[0679] Nano graphite 1.00%

[0680] This results in a homogeneous dispersion with a TSI index of 0.4,

[0681] This product is therefore stable enough to be used later as a graphene-based additive.

[0682] Example 16: aqueous dispersion with chitosan and dispersant and nano-graphite / chitosan weight ratio-1.25 Similar to what is described in Examples 12, 13, 14 and 15, demineralized water (1052.6 g) and glacial acetic acid (1.8 g) are initially loaded into the reactor of Example 1.

[0683] Next, the Silverson mixer is immersed in the reactor under the same conditions and in the manner described in Example 1.

[0684] Similar to Examples 12 and 13, once the mixer is set to a speed of 6000 rpm, 9.6 g of medium molecular weight chitosan is added while stirring as an exfoliation adjuvant.

[0685] Once the chitosan premix phase is complete, "nano 27" graphite (12 g) is added, again at 6000 rpm, keeping the stirring constant for a period of about 90 min.

[0686] At the end of this period, a peristaltic pump (8 mL / min) is used to add a dispersant in the form of a previously prepared aqueous solution consisting of water (120 g) and tristyrylphenol ethoxylate "Soprophor" (3.60 g).

[0687] Foam formation within the reaction slurry is managed by the addition of defoamer (0.42 g) known as "Moussex 9157 SE".

[0688] The total mixing time at 6000 rpm of the entire dispersion, once the graphitic substrate has been added, is not continued beyond three hours.

[0689] The dispersion was prepared to obtain the following composition in % weight Water 97.72%

[0690] Glacial acetic acid 0.15%

[0691] Chitosan 0.80%

[0692] Nano graphite 1.00%

[0693] Tristyrylphenol ethoxylate "Soprophor" 0.30%

[0694] Anti to am 0.03%

[0695] This results in a homogeneous dispersion with a TSI index of 0.5 and a. graphite / exfoliant weight ratio of 1.25.

[0696] This product is therefore sufficiently stable to be used. later as a graphene-containing additive.

[0697] Example 17: aqueous dispersion with chitosan, dispersant and mixing of chitosan at increasing rates (different procedure to Example 16)

[0698] Similar to what is described in Examples 12, 13, 14, 15 and 16, demineralized water (1368.5 g) and glacial acetic acid (2.1 g) are initially loaded into the reactor of Example

[0699] 1.

[0700] Next, the Silverson mixer is immersed in the reactor under the same conditions and in the manner described in Example

[0701] 1.

[0702] Sim.il ar to Examples 14 and 15, once the mixer is set to a speed of 3000 rpm, 11.2 q of medium molecular weight chitosan is added while stirring as an exfoliation adjuvant. During this 30-minute phase, the Silverson mixer is increased from 3000 rpm to 6000 rpm to facilitate the correct mixing of the chitosan in the reaction environment.

[0703] Once the chitosan has been solubilized, 4.20 g of tristyrylphenol ethoxylate "Soprophor" are added, while stirring constantly at 6000 rpm.

[0704] In this 30-minute phase, the interaction between chitosan and tristyrylphenol ethoxylate is promoted, which exfoliates / stabilizes materials with a nano-graphitic structure.

[0705] Next, "nano 27" graphite (12 g) is added, again at 6000 rpm, while stirring constantly for a period of about 90 min.

[0706] The total mixing time at 6000 rpm of the entire dispersion, once the graphitic substrate has been added, is not continued beyond three hours.

[0707] The dispersion was prepared to obtain the following composition in % weight:

[0708] WcitGi? 97,75%

[0709] Glacial acetic acid 0.15%

[0710] Chitosan 0.80%

[0711] Tristyrylphenol ethoxylate "Soprophor" 0.30%

[0712] Nano graphite 1.00%

[0713] This results in a homogeneous dispersion with a TSI index of 0.4 and a graphite / exfoliant weight ratio of 1.25. This product is therefore stable enough to be used later as a graphene-based additive.

[0714] Example 18: aqueous dispersion with chitosan, dispersant and nano~graphite / chitosan weight ratio™1

[0715] Similar to what is described in Examples 12, 13, 14, 15, 16 and 17, demineralized water (1122.0 g) and glacial acetic acid (2.4 g) are initially loaded into the reactor of Example 1.

[0716] Next, the Silverson mixer is immersed in the reactor under the conditions and in the manner described in Example 1.

[0717] Similar to Examples 12 and 13, once the mixer is set to a speed of 6000 rpm, 12 g of medium molecular weight chitosan is added as an exfoliation adjuvant.

[0718] Once the chitosan premix phase is complete, Nano 27 graphite (12 g) is added, again while stirring at 6000 rpm, maintaining the stirring speed for a period of about 90 min.

[0719] At the end of this period, a peristaltic pump (8 mL / min) is used to add a dispersant in the form of a previously prepared aqueous solution consisting of water (48 g) and tristyrylphenol ethoxylate "Soprophor" (3.60 g).

[0720] Foam formation within the reaction slurry is managed by the addition of a defoamer (0.42 g) called "Moussex 9157 SE". The total mixing time at 6000 rpm of the entire dispersion, once the graphitic substrate has been added, is not continued beyond three hours, similar to the previous examples.

[0721] The dispersion was prepared to obtain the following composition in % weight:

[0722] Water 97.47%

[0723] Glacial acetic acid 0.20%

[0724] Chitosan 1.00%

[0725] Nano graphite 1 .00%;

[0726] Tristyrylphenol ethoxylate Soprophor" 0.30%

[0727] Anti foam 0.03%

[0728] This results in a homogeneous dispersion with a TS1 index ot 0.5 and a graphite / extoliant weight ratio of 1.

[0729] This product is therefore sufficiently stable to be used later as a graphene-containing additive.

[0730] Example 19: aqueous dispersion with chitosan, dispersant and nano-graphite / chitosan weight ratio™2

[0731] Similar to what is described in Examples 12, 13, 14,

[0732] 15 , 16, 17 and 18, demineralized water (1056.6 g) and glacial acetic acid (1.8 g) are initially loaded into the reactor of

[0733] Example 1.

[0734] The Si Iverson mixer is then immersed, in the reactor, under the conditions and in the manner described in Example

[0735] 1. Similar to Examples 12 and 13, once the mixer is set to a speed of 6000 rpm, 6 g of medium molecular weight chitosan is added as an exfoliation adjuvant.

[0736] Once the chitosan premix phase is complete, Nano 27 graphite (12 g) is added, while stirring at 6000 rpm, continuing stirring for a period of about 90 min.

[0737] At the end of this period, a peristaltic pump (8 mL / min) is used to add a dispersant in the form of a previously prepared solution consisting of water (120 g) and tristyrylphenol ethoxylate "Soprophor" (3.60 g).

[0738] No foaming takes place during this process.

[0739] The total mixing time at 6000 rpm of the entire dispersion, once the graphitic substrate has been added, is not continued beyond three hours, similar to the previous examples.

[0740] The dispersion was prepared to obtain the following composition in % weight:

[0741] Water 98.05%

[0742] Glacial acetic acid 0.15%

[0743] Chitosan 1.00%

[0744] Nano graphite 1.00%

[0745] Tristyrylphenol ethoxylate "Soprophor" 0.30%;

[0746] This results in a homogeneous dispersion with a TSi index of 0.7 and a graphite / exfoliant weight ratio of 1. This product is therefore sufficiently stable to be used later as a graphene-containing additive.

[0747] Example 20: aqueous dispersion with sodium alginate as exfoliant + stabilizer (polyalkylene glycol)

[0748] The s ame reactor as in Example 1 is initially loaded with demineralized, water (1036.1 g) and. sodium alginate (10.4 g) as an exfoliation adjuvant.

[0749] Next, the Silverson mixer 1 s immersed. in the reactor under the conditions and in the manner described in Exa.Tii.ple

[0750] 1.

[0751] Once the mixer is set to a speed of 6000 rpm, 13 g o f

[0752] "Nano 27 " graphite is added, while stirring at a constant speed of 6000 rpm for 90 min.

[0753] After this period, using a peristaltic pump ( 8mL / min . ) , a stabilizer is fed in the form of a pre-mixed aqueous solution c o n s i s t i n g of water (234 g) and water-soluble polyalkylene glycol called "Rokolub 60-D-

[0754] 150" (6.50 g) .

[0755] Stirring at 6000 rpm .1 s continued no longer than three hours (from the addition of the graphitic substrate) .

[0756] The dispersion was prepared to obtain the fol lowing composition in % weight:

[0757] Water 97.70%

[0758] Sodium alginate 0.80% Nano graphite 1.00%

[0759] Polyalkylene glycol "Rokolub 60-D-150" 0.50%

[0760] This results in a homogeneous dispersion with a TSI index of 0.5 and a graphite / exfoliant ratio of 1.25.

[0761] This product is therefore stable enough to be used later as a graphene-based additive.

[0762] Example 21: aqueous dispersion with sodium alginate, stabilizer (PVA) and dispersant (tristyrylphenol ethoxylate) Similar to Example 18, in the reactor of Example 1, demineralized water (871.8 g) and sodium alginate (4.8 g) are initially loaded as an exfoliation adjuvant.

[0763] Next, the Silverson mixer is immersed in the reactor under the conditions and manner described in Example 1.

[0764] Once the mixer has been set to a speed of 6000 rpm, mixing is carried out until sodium alginate is completely miscible in water (30 min.) and then 12 g of "Nano 27" graphite is added, while stirring at a speed of 6000 rpm for a further 30 min.

[0765] At the end of this phase, a first aliquot of dispersant is added by means of a peristaltic pump (8 ml / min) in the form of a previously prepared aqueous solution consisting of wale.: 2 g) and tristyrylphenol ethoxylate (1.20 g) called "Soprophor".

[0766] Stirring is continued for 30 minutes and then a stabilizer in the form of a previously prepared aqueous solution consisting of water (216 g) and polyvinyl alcohol (7.2 g) is added by means of a peristaltic pump.

[0767] During this process, foam formation is managed by the addition of defoamer (1.8 g) called Moussex 6157.

[0768] Stirring is continued for a further 30 minutes, then a further portion of dispersant is fed (8 mL / min) via a peristaltic pump in the form of a solution consisting of water (42 g) and tristyrylphenol ethoxylate (1.20 g) called "Soprophor".

[0769] Stirring at 6000 rpm is continued no longer than three hours (from the addition of the graphitic substrate).

[0770] The dispersion was prepared to obtain the following composition in % weight:

[0771] WcitGi? 97,65%

[0772] Sodium alginate 0.40%

[0773] Nano graphite 1.00%

[0774] Tristyrylphenol ethoxylate "Soprophor" 0.20%

[0775] Polyvinyl alcohol (PVA) 0.60 %

[0776] Antifoam 0.15%

[0777] This results in a homogeneous dispersion with a TSI index of 0.5 and a graphite / exfoliant ratio of 2.5.

[0778] This product is therefore stable enough to be used later as a graphene-based additive.

[0779] Example 22: aqueous dispersion with PVP as exfoliant and

[0780] Metolat 392 as dispersant The same reactor as in Example 1 is initially loaded with demineralized water (1300.6 g), and PVP K30 (14.0 g) as an exfoliation adjuvant.

[0781] Next, the Silverson mixer is immersed in the reactor, as described in Example 1.

[0782] Once the mixer has been set to a speed of 3000 rpm, 14 g of Nano 27 graphite is added, while stirring at a constant speed for 30 minutes. This premix phase between the exfoliating agent (PVP) and Nano 27 graphite speeds up and facilitates the interaction (adsorption) between the exfoliating agent (PVP) and the substrate to be exfoliated (Nano 27 graphite).

[0783] After the 30 minutes at 3000 rpm, the Silverson rpm is increased to 6000 rpm and the mixture (slurry) is kept under these stirring conditions for about 90 minutes, at autogenous temperatures not exceeding 70°C.

[0784] At the end of this period, a dispersant is added by means of a peristaltic pump (8 mL / min) in the form of a pre-mixed aqueous solution consisting of water (56 g), and water-soluble polymeric dispersant called "Metolat 392" (14.0 g).

[0785] During this step, an antifoam agent (0.8 g) called "Moussex 9157 SE" is co-fed to reduce foaming. The overall mixture (slurry) is kept at 6000 rpm for a further 60 min.

[0786] The total mixing time at 6000 rpm of the entire dispersion is not continued beyond three hours.

[0787] The dispersion was prepared to obtain the following composition in % weight:

[0788] Water 96.94%

[0789] PVP K30 1%

[0790] Nano graphite 1.00%

[0791] Dispersant Metolat 392 1%

[0792] Antifoam 0.06%

[0793] This results in a homogeneous dispersion with a TSI index of 0.4 and a graphite / exfoliant ratio of 1.

[0794] This product can therefore be used as a graphenecontaining additive.

[0795] Example 22.bis

[0796] Example 22 is repeated keeping the quantities of the components constant but first mixing all components with the exclusion of nano 27 graphite (demineralized water, PVP K30, defoamer "Moussex 951 SE" and dispersant "Metolat 392". It is mixed at 6000 rpm for 30 minutes and then Nano 27 graphite is added. The resulting slurry is then mixed with Silverson at 6000 rpm for up to three hours. This preparation process was also found to lead to homogeneous dispersions with acceptable TSI values for the purposes of the present invention (TSI value of 1).

[0797] EXAMPLES 23-24 OF THE PREPARATION OF COATING COMPOSITIONS

[0798] AND PROPERTIES OF COATED SUBSTRATES

[0799] The following are EXAMPLES OF ITEMS prepared using coating compositions comprising the dispersions covered by the invention.

[0800] Their antibacterial and antiviral properties are demonstrated by comparing them with those of the same item with a coating not comprising the dispersions of the invention (comparative examples 7 and 8).

[0801] Comparative example 7 (100% enamel)

[0802] A typical enamel for interior wall applications marketed by the company San Marco is applied by means of a "roller" application on a Forex substrate for the determination of antibacterial and antiviral properties according to the methods indicated in the text.

[0803] After coating the substrate, it is left to dry for a period of three hours in order to promote the anchoring of the enamel system on the surface.

[0804] The medium thus obtained does not release the deposited substance and is therefore considered suitable for carrying out tests for the evaluation of antibacterial and antiviral properties . The results of antibacterial and antiviral tests performed according to the methods reported in the text are summarised in Table 1 below.

[0805] Example 23

[0806] An aliquot of the dispersion from Example 3 is mixed with the commercial enamel described above (enamel from Comparative Example 7) so that the aforementioned dispersion from Example 3 represents 25% by weight of the final formulation. This mixing is done using a typical Cowles mixer with a mixing speed of 1000 rpm until the entire formulation is completely homogenized.

[0807] At the end of the mixing period, the product thus obtained is deposited by means of a roller on a Forex® (semiexpanded PVC) support for the determination of antibacterial and antiviral properties according to the methods indicated in the text.

[0808] After coating the substrate, it is left to dry for a period of three hours in order to promote the anchoring of the enamel system on the surface.

[0809] The medium thus obtained does not release the deposited substance and is therefore considered suitable for carrying out tests for the evaluation of antibacterial and antiviral properties. Ill

[0810] The results of antibacterial and antiviral tests performed according to the methods reported in the text are summarised in Table 1 below.

[0811] Table 1: antibacte rial and antiviral te st results

[0812] From above results, it can be deduced that the coating composition (enamel) comprising the dispersion of the invention has very good virucidal and bactericidal activity, the latter being significantly higher than that of the same enamel not comprising said dispersion ot the invention.

[0813] Comparative Example 8 (untreated NWF)

[0814] A typical non-woven fabric (NWF) material by Ansell is cut so that it has the dimensions 7.5 cm * 2.5 cm.

[0815] This material is adhered to a vitreous surface

[0816] (microscope slide) using a special adhesive material (biadhesive).

[0817] Antibacterial and antiviral tests are carried out on this item according to the methods described in the text

[0818] The results are reported in Table 2 below.

[0819] Example 24 The dispersion ot the invention described in Example 5 is used for coating, by spraying with an airbrush, the nonwoven fabric (NWF) of the item prepared as described in Comparative Example 8.

[0820] Once the coating step is complete, it is left to dry for a period of three hours in order to promote the anchoring of the dispersion of the invention on the surface of the non-woven fabric.

[0821] The item thus obtained does not release the deposited substance and is therefore considered suitable for carrying out tests for the evaluation of antibacterial and antiviral properties, the results of which are shown in Table 2.

[0822] From the above results, it can be deduced that the composition for coating the NWF, consisting of the dispersion of the invention, gives the item excellent virucidal and bactericidal properties, the latter characteristic being completely absent in NWF.

[0823] Example 25

[0824] Using the same equipment as in example 1, a dispersion was prepared using a different dispersant (SDS) and the following amounts (% by weight) of reagents as follows: - 0.4% by weight PVP K30;

[0825] - 0.4% by weight sodium dodecyl sulphate (SDS);

[0826] 1% nano-graphite;

[0827] - Water for the remaining portion to reach 100%.

[0828] Similar to some previous examples, a premix of PVP K-30 and graphite was first prepared while stirring at 2500 rpm for 30 minutes. The mixing speed was then increased to 6000 rpm and after 90 minutes, the dispersant was added drop by drop for about 20-30 minutes, continuing stirring at 6000 rpm and then continuing mixing at 6000 rpm for a total time of 180 minutes. Exfoliation was therefore conducted for 3h at 6000 rpm.

[0829] Trie TSI value is 0. / .

[0830] The concentration of exfoliated allotrope dispersed in solution is 91% by weight (at time zero) with respect to the initial concentration of allotrope not yet exfoliated, as measured by UV-VIS.

[0831] Comparative Example 26

[0832] Example 25 was repeated but using a dispersant not in accordance with the present invention, sodium dodecylbenzene sulphonate (SDBS)

[0833] The TSI value is 1.4.

[0834] The concentration of exfoliated allotrope dispersed in solution is 89% weight (at time zero) with respect to the initial concentration of allotrope not yet exfoliated, as measured by UV-VIS.

[0835] Comparison of the data from Comparative Example 26 with those of Example 25 shows that although the extent of exfoliation of the two dispersions is comparable, the TSI values of the Comparative Example do not meet the required stabiiity requirernents.

[0836] Example 27

[0837] The procedure of Example 25 was repeated but without adding any dispersants and using the following quantities (% by weight) of reagents as follows:

[0838] -- 0.4% by weight PVP K-30;

[0839] - 1% nano-graphite;

[0840] ~ Water for the remaining portion to reach 100%.

[0841] The nano-graphite / exfoliant weight ratio is 2.5.

[0842] The TSI value is 0.8.

[0843] The concentration of exfoliated allotrope dispersed in solution is 86% by weight (at time zero) with respect to the initial concentration of allotrope not yet exfoliated, as measured by UV-VIS.

[0844] By comparing the data of Example 27 with the data of Example 25, both in accordance with the invention, it can be seen that the addition of dispersant slightly lowers the TSI value and increases the % of exfoliated graphite dispersed at time 0 measured by UV-VIS. Example 28: dispersion in water with PVP as exfoliating agent and Metolat 392 as dispersant including an acidity regulator

[0845] Example 22 of the invention has been repeated except for the absence of antifoam and for the amounts of Metolat 392 and PVP K30 which have been used in such amount to obtain an aqueous dispersion of exfoliated graphite (1% by weight) containing 0,6% by weight of Metolat and 0,6% by weight of PVP K30.

[0846] The above dispersion had a pH equal to 3,5.

[0847] AMP has been then added to said dispersion as acidity regulator, in amounts of 0,09% by weight in order to achieve si pH value of 8,5.

[0848] The final dispersion so obtained had the following composition by weight (%):

[0849] PVP K30 0,6%

[0850] Nano graphite 1,00%

[0851] Metolat 392 Dispersant 0,6%

[0852] AMP 0,09%

[0853] Water for the remaining portion to reach 100%.

[0854] It has been obtained a homogeneous dispersion, having a TSI value lower than 1 and a graphite / exfoliant weight ratio of 1.7.

[0855] This product can therefore be used as a graphenecontaining additive. Example 29 (comparative)

[0856] Following the procedure of comparative example 6, it is prepared a dispersion without BAG, in the presence of antifoam "Moussex 9157 SE" and of PVA as adjuvant of exfoliation known in the art (see for example Yaodong Li et al., "Poly (vinyl alcohol)-Assisted Exfoliation of van der Waals Materials", ACS Omega 2022, 7, 38774-38781; Zeba Khanam et al., "High-concentration graphene dispersions prepared via exfoliation of graphite in PVA / H2O green solvent system using high-shear forces", Journal of nanoparticle research, 1 August 2021, Materials Science, Chemistry).

[0857] The used amounts of water, PVA, graphite and antifoam are those to obtain a dispersion having the following composition by weight:

[0858] Nano-graphite 1,00% Antifoam 0,20% PVA 0,50% Water for the remaining portion to reach 100%.

[0859] The dispersion so obtained has shown a TSI value higher than 10 and thus the dispersion is not sufficiently stable to be used at a later time as graphene-containing additive. ummary table of preparation examples l~22bis and 25-27

[0860]

Claims

CLAIMS1. A dispersion comprising at least one sp2carbon allotrope non-functionalized with covalent bonds in exfoliated form, further comprising- a dispersion liquid selected from water, an organic solvent, or combinations thereof;- at least one polymeric compound capable of adjuvating the exfoliation of said allotrope selected from the group consisting of(a) polysaccharides, possibly in the form of salts;(b) polymeric compounds belonging to the polyvinyl pyrrolidone class having general formula:Wherein n==:integer number equal to at least 20, possibly in the form of salts;(c) their combinations at least one optional compound selected from a dispersing agent, a stabilizing agent or a combination thereof; and opt.1.ona.s.1.y■■■ at least one antimicrobial agent and / or at least oneantifoam agent, wherein the weight ratio between the allotrope contained in the dispersion and the extoliant is greater than, or equal to,0.6, preferably greater than, or equal to, 0.8, more preferably greater than, or equal to, 1, said allotrope in exfoliated form deriving from mechanical exfoliation at high shear stress.

2. Dispersion according to claim 1, having a TSI (Turbiscan Stability Index) value less than or equal to 1 (measured after 3 days), preferably less than or equal to 0.9, more preferably less than or equal to 0.5 (measured after 3 days).

3. Dispersions according to claim 1 or 2, wherein the content of said allotrope in exfoliated form is at least 70% by weight (at time zero) compared to the amount of allotrope contained in the dispersion.

4. Dispersion according to any of the previous claims 1-3, wherein the water, the organic solvent or a combination thereof is present in the dispersion in an amount within the range (% by weight with respect to the overall weight of the dispersion) that varies from 80% to 99%.

5. Dispersion according to any of the previous claims 1-4, wherein the at least one sp2carbon allotrope nonfunctionalized with covalent bonds (i.e. having nocovalently bonded functionalisations) is selected from graphites, nano-graphites, graphene, fullerene, carbon nanotubes excluding graphene oxide, reduced graphene oxide, graphene covalently functionalized; preferably nano-graphite (FLG).

6. Dispersion according to any of the previous claims 1-5, wherein the concentration of said allotrope contained in the dispersion is included in the range that varies from 0.1% to 10% by weight with respect to the overall weight of the dispersion.

7. Dispersion according to any of the previous claims 1-6, wherein the at least one exfoliation adjuvant compound (exfoliant) is present in the dispersion in an amount ranging from 0.1% to 10% by weight, preferably from 1% to 3% by weight, with respect to the total weight of the dispersion.

8. Dispersion according to any one of the previous claims 1-7, wherein the organic solvent is an alcohol, an ester, an ether or combinations thereof, preferably alcohols, more preferably isopropanol.

9. Dispersion according to any one of the preceding claims 1-8, further comprising one or more acidity regulators, preferably an aminoalcohol and / or an aminoacid.

10. Dispersion according to claim 9, wherein the one or more acidity regulators are in a total amount ranging from 0.01% by weight to 1.5% by weight, preferably in amountslower than 1% by weight, more preferably lower than 0.1%, e.g. 0.09% by weight, with respect to the total weight of the dispersion.

11. Dispersion according to any of the previous claims 1-10, comprising:- water, organic solvent or their combination 80%- 99%,- graphite 0.1%-10%,- exfoliant, preferably chitosan or PVP 0.1%-10%- dispersing agent 0.10%-5%,- stabilizing agent 0.4-5%; and optionally antimicrobial agent 0.1%-20%, antifoam agent 0.01%-0.5% wherein the weight ratio between the graphite and the exfoliation adjuvant is greater than, or equal to, 0.6, being 100% the sum of the percentages of the aforementioned components present in the dispersion, said dispersion being able to include a combination of said dispersing agent and said stabilizing agent.

12. Process for preparing a dispersion in water and / or in organic solvent as defined in any of the previous claims 1-11, comprising the phases of:(a) dispersing in water, in an organic solvent as defined in any one of the preceding claims or in a combinationthereof, under stirring, sp2arbon a1iotrope not functionalized with covalent bonds as defined in anyone of the preceding claims, in the presence of a compound capable of adjuvating the exfoliation of said allotrope as defined as defined in anyone of the preceding claims and optionally in the presence of at least one compound selected from a dispersing agent, a stabilizing agent as defined in anyone of the preceding claims or a combination thereof, and optionally in the presence of at least one antimicrobial agent and / or at least one antifoam agent and / or acidity regulator as defined in anyone of the preceding claims;(ID) subjecting the dispersion of phase (a) to a mechanical homogenization at high shear stress, mixing said dispersion obtained in phase (a) with a mixing speed greater than or equal to the speed of the previous phase (a), preferably a speed included in the range that varies from 1000 rpm to 10,000 rpm, to obtain a dispersion comprising said sp2carbon allotrope in exfoliated form, said phases (a) and (b) can be carried out in sequence or simu11aneously, and said components indicated above can be added to water and / or organic solvent in any order and / or mixed in any O£’QGI?f the quantity of sp2carbon allotrope and that of exfoliation adjuvant to be added are selected in such a waythat their weight ratio is greater than, or equal to, 0.6.Process according to claim 12, wherein the duration of the mechanical homogenization phase of the high shear stress phase (b) is in the range of 0.5 hours to 12 hours, preferably in the range of 0.5 to 8 hours, even more preferably in the range of 0.5 to 6 hours.

14. Process according to claim 12 or 13, wherein the temperature at which phases (a), (b) are carried out is comprised in the range from 25°C to 90°C, preferably in the range from 35°C to 85°C, more preferably in the range from 50°C to 70°C.

15. Process according to any one of the previous claims from 12 to 14, wherein the phases (a), (b) are carried out at an absolute pressure included in the range from 0.5 bar to 2 bar absolute, preferably in the range from 0.8 bar to 1.2 bar, more preferably at atmospheric pressure.

16. Process according to any of the previous claims 12-15, wherein the stirring of phase (a) and the high shear mechanical homogenization of phase (b) is achieved by means of at least one rotor-stator mixer, preferably Silverson type mixer.

17. Additive for coating compositions of substrates to impart antimicrobial properties, said additive being in the form of a dispersion of a non-functionalized and exfoliated sp2carbon allotrope as defined in any of the previous claims1-11.

18. A coating composition having antimicrobial properties comprising the dispersion as defined in any of the previous claims 1-11 and a paint or enamel, wherein the paint or enamel is present in an amount ranging from 1% to 99% by weight of paint or enamel compared to the overall weight of the coating composition, the remaining part to 100% being made up of said dispersion.

19. The process for preparing the composition as defined in claim 18, said process comprising mixing a paint or enamel with the sp2carbon allotrope dispersion as defined in any of the previous claims 1-11.

20. Use of a dispersion as defined in any of the previous claims 1-11 as a direct coating agent of substrates in textile material to impart antimicrobial properties.

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