* * *

The present invention relates to a mixture for treatment of one leather layer and a respective treatment method, which gives the treated leather layer high characteristics of mechanical resistance, hygiene and softness to touch.

Graphite, thanks to its chemical-physical characteristics, is one of the materials that has aroused much interest in the scientific community in recent years. In fact, from graphite graphene can be obtained, a "two-dimensional" material with a thickness equal to that of a single atom, very light and very resistant, currently considered the most resistant material among the known ones, even more resistant than diamond. Graphene is an excellent electricity conductor, it is transparent but also flexible, so it is currently used in many technical sectors, including the textile and leather processing sector. Graphene can make a fabric or leather treated therewith waterproof, highly conductive, and more resistant to mechanical stresses than untreated leather. An example of leather treatment methods using graphene is taught in CN 109023985. Other leather treatment methods according to the prior art are taught in CN 105400336, EP 2954073 and US 5759706.

However, leather worked with graphene suffers from some drawbacks.

Firstly, it is rough to the touch, so it is not always usable for the production of clothing, leather goods and footwear or for the production of coatings in the automotive sector, where the finished product is required to be soft to the touch. Leather worked with graphene is expensive, as the graphene production process has very high costs.

Furthermore, leather treated with graphene takes on a greyish color and this is a drawback, as in the sector, it is required that leather is produced in various colors.

Finally, various market researches indicate an ever-growing desire among the population for antibacterial products, therefore the need is felt to be able to produce improved leather, having high characteristics of attractiveness to the touch (softness) and to the eye, which is also antibacterial and more resistant to mechanical stress than traditional leather.

Accordingly, the object of the present invention is that of improving, in general, the state of the art in the leather processing sector and, in particular, providing one leather layer having high characteristics of mechanical resistance but also high characteristics of attractiveness to the touch (softness) and to the eye, as well as antibacterial characteristic.

Another object of the present invention is to provide one leather layer having high characteristics of mechanical resistance, attractiveness to the touch (softness) and to the eye, as well as antibacterial characteristic at reduced costs with respect to one graphene treated leather layer.

It is a specific object of the present invention a mixture for treatment of one leather layer having at least one surface S, comprising, per square meter of said surface S to be treated:

- distilled water, in one amount by weight between 20 mg and 150 mg, optionally comprised between 30 mg and 125 mg, more optionally comprised between 40 mg and 100 mg;

- opaque wax, in one amount by weight comprised between 10 mg and 30 mg, optionally between 15 mg and 25 mg, more optionally equal to 20 mg;

- a polymeric composition comprising polyurethane, in one amount by weight comprised between 30 mg and 50 mg, optionally between 35 mg and 45 mg, more optionally equal to 40 mg;

- isopropyl alcohol, in one amount by weight comprised between 30 mg and 100 mg, optionally between 40 mg and 90 mg, more optionally between 50 mg and 80 mg;

- a graphite-based liquid solution, in one amount by weight between 30 mg and 100 mg, optionally between 40 mg and 90 mg, more optionally between 50 mg and 80 mg;

- animal casein, in one amount by weight comprised between 25 mg and 75 mg, optionally between 30 mg and 70 mg, more optionally between 35 mg and 65 mg;

- catalyzing polyaziridine, in one amount by weight between 3 mg and 12 mg, optionally between 4 mg and 11 mg, more optionally between 5 and 10 mg.

According to another aspect of the invention, said graphite-based liquid solution can comprise, by percentage weight:

- protein, optionally casein, between 10 % and 20%, optionally equal to 15%,

- graphite powder, between 50 % and 70%, optionally equal to 60%,

- oils of animal or vegetable origin, between 3% and 7%, optionally equal to 5%,

- distilled water, between 3 % and 8%, optionally equal to 5%, and

- casein between, between 10 % and 20%, optionally equal to 15%, wherein the above said amounts by percentage weight of said components of said graphitebased liquid solution can vary in said intervals in such a way that their sum is always equal to According to a further aspect of the invention, said graphite powder can comprise graphite granules, wherein the distribution curve of the dimensions of said granules is represented by the following indicators: D ¹⁰ = 3-6 micron;

D ⁵⁰ = 10-25 micron;

D ⁹⁰ = 50-70 micron; where D ¹⁰ , D ⁵⁰ and D ⁹⁰ are indicators that represent the values of the diameters of said granules of said graphite powder, for weight percentage of 10%, 50% and 90%, respectively.

According to an additional aspect of the invention, said mixture can also comprise at least one pigment in one amount by weight, per square meter of said at least one surface S of said leather layer to be treated, comprised between 10 mg and 40 mg, optionally comprised between 15 mg and 35 mg, more optionally comprised between 20 and 30 mg, wherein said at least one pigment can be optionally a charcoal powder-based pigment.

It is also an object of the present invention a method for treatment of a leather layer having at least one surface S, said method comprising or consisting of the following operational steps:

A. covering said at least one surface S of said leather layer with said mixture according to any previous claim;

B. drying said at least one surface S of said layer;

C. covering said at least one surface S of said leather layer with said mixture according to any previous claim; and

D. drying said at least one surface S di said leather layer.

According to another aspect of the invention, said step can comprise spraying, optionally uniformly, said mixture on said at least one surface S of said leather layer with a delivery pressure comprised between 0.5 and 0.8 atmospheres, for a spraying interval comprised between 30 and 50 seconds, optionally equal to 40 seconds, wherein said mixture can be at room temperature and wherein said step C can be equal to said step A.

According to a further aspect of the invention, said step B can comprise drying said layer of said leather, optionally through steam, at a temperature comprised between 60 and 90°C, optionally comprised between 70 and 80°C, for a drying interval comprised between 20 and 40 seconds, optionally equal to 30 seconds, and wherein said step D can be equal to said step B.

According to an additional aspect of the invention, when said mixture is obtained according to claim 4, wherein said steps A to D are carried out at least three times.

According to another aspect of the invention, when said mixture does not comprise at least one pigment, said steps A to D are carried out at least three times and said method can comprise, at the end of the last executed step D, at least one step of traditional dyeing DI of said at least one surface S di said leather layer, optionally through spraying.

According to a further aspect of the invention, said method can further comprise the following operational steps, after the last executed step D or step DI, if DI carried out after step D:

E. carrying out on said leather layer at least one first finishing procedure, configured for further fixing said mixture to said leather layer; and/or

F. carrying out on said leather layer at least one second finishing procedure, configured for making said leather layer soft to the touch.

According to an additional aspect of the invention, said first finishing procedure can comprise the following sub-steps:

E.l covering said at least one surface S of said leather layer by spraying, optionally uniformly, at least one first nitrocellulose aqueous emulsion, wherein said spraying is carried out at a delivery pressure comprised between 0.5 and 0.8 atmospheres, with said at least one first nitrocellulose aqueous emulsion at room temperature, for a spraying interval comprised between 30 and 50 seconds, optionally equal to 40 seconds;

E.2 drying, optionally through steam, said at least one surface S of said leather layer, at a temperature comprised between 60°C and 90°C, optionally comprised between 70°C and 80°C, for a drying interval comprised between 20 and 40 seconds, optionally equal to 30 seconds;

E.3. repeating once said sub-step E.l; and

E.4 repeating once said sub-step E.2.

According to another aspect of the invention, said at least one first nitrocellulose aqueous emulsion can comprise, by percentage weight:

- distilled water, between 3% and 7%, optionally equal to 5%;

- nitrocellulose powder, between 40% and 60%, optionally equal to 50%;

- emulsifiers, of any type suitable to keep the abovesaid nitrocellulose powder into emulsion, between 3% and 7%, optionally equal to 5%; and

- alcohols, optionally ethyl alcohol or isopropyl alcohol, between 30% and 50%, optionally equal to 40%, wherein said amounts by percentage weight of said components of said first nitrocellulose aqueous emulsion vary within said percentage intervals in such a way that their sum is always equal to 100%.

According to a further aspect of the invention, said at least one second finishing procedure can comprise the following sub-steps:

F.l covering said at least one surface S of said leather layer, by spraying, optionally uniformly, at least one second hydro-emulsion, wherein said spraying is carried out at a delivery pressure comprised between 0.5 and 0.8 atmospheres, with said at least one second hydro-emulsion at room temperature, for a spraying interval comprised between 30 and 50 seconds, optionally equal to 40 seconds;

F.2 drying, optionally by steam, said at least one surface S di said leather layer, at a temperature comprised between 60°C and 90°C, optionally comprised between 70°C and 80°C, for a drying interval comprised between 20 and 40 seconds, optionally equal to 30 seconds;

F.3. repeating once said sub-step F.l;

F.4 repeating once said sub-step F.2; and

F.5 leaving to rest said leather layer so finished for a resting interval, optionally not less than one hour.

According to an additional aspect of the invention, said at least one second hydroemulsion can comprise, per square meter of said at least one surface S of said leather layer to be finished:

- distilled water, in one amount by weight comprised between 80 mg and 120 mg, optionally comprised between 90 mg and 110 mg, more optionally equal to 100 mg;

- one fat touch feel modifier, in one amount by weight comprised between 20 mg and 30 mg, optionally comprised between 23 mg and 27 mg, more optionally equal to 25 mg; and

- one silicone-based touch feel modifier, in one amount by weight comprised between 4 mg and 8 mg, optionally comprised between 5 mg and 7 mg, more optionally equal to 6 mg.

According to another aspect of the invention, said method can comprise one step G of pressing said leather layer thus treated and finished, at a pressure comprised between 35 and 45 atmospheres, optionally equal to 40 atmospheres, at a temperature comprised between 100 and 120 °C, optionally equal to 110°C, for a pressing interval comprised between 1 and 15 seconds, optionally comprised between 2 and 10 seconds.

The present invention will now be described, for illustrative but not limiting purposes, according to preferred embodiments thereof, with particular reference to the Figures of the attached drawings, wherein:

Figure 1 shows a flowchart of the main steps of the leather treatment method according to the present invention;

Figure 2 is a flowchart of a first finishing procedure of the invention;

Figure 3 illustrates a flowchart of a second finishing procedure of the invention; and

Figure 4 shows in a Table some results of experimental tests carried out with reference to the method of the invention.

Before going into the merit of the present invention, it should be remembered that leather, is classified based on various criteria which may concern, for example, the type of tanning, the layer of the epidermis of the animal used, the type of animal from which the leather is obtained and the finishing degree, as well as based on the cut and shape or use.

In view of this, it is pointed out that the present invention is advantageously applicable to the sector of leather layers processing:

- of bovine or sheep and goat origin, in particular of veal, sheep, goat or crossbreed,

- semi-finished, i.e. not further treated or in the natural state, after the pre-tanning and tanning process, and

- grain side, i.e. the part of the skin that originally included the animal's hair.

In any case, the present invention can also be used for treatment of a leather layer of different origin and/or on the split side.

It is a specific object of the present invention a mixture, configured to be used in a treatment method of at least one layer of the abovesaid leather having one surface S, comprising, per square meter of said surface S to be treated:

- distilled water, in one amount by weight between 20 mg and 150 mg, optionally comprised between 30 mg and 125 mg, more optionally comprised between 40 mg and 100 mg;

- opaque wax, in one amount by weight comprised between 10 mg and 30 mg, optionally between 15 mg and 25 mg, more optionally equal to 20 mg;

- a polymeric composition comprising polyurethane, in one amount by weight comprised between 30 mg and 50 mg, optionally between 35 mg and 45 mg, more optionally equal to 40 mg;

- isopropyl alcohol, in one amount by weight comprised between 30 mg and 100 mg, optionally between 40 mg and 90 mg, more optionally between 50 mg and 80 mg;

- a graphite-based liquid solution, in one amount by weight between 30 mg and 100 mg, optionally between 40 mg and 90 mg, more optionally between 50 mg and 80 mg;

- animal casein, in one amount by weight comprised between 25 mg and 75 mg, optionally between 30 mg and 70 mg, more optionally between 35 mg and 65 mg; and

- catalyzing polyaziridine, in one amount by weight between 3 mg and 12 mg, optionally between 4 mg and 11 mg, more optionally between 5 and 10 mg.

According to a preferred embodiment of the invention, the mixture opaque wax comprises a solution of filtered natural waxes, of which (in percentage weight): candle wax between 15% and 25%, optionally equal to 20%, and cresol waxes between 25% and 35%, optionally equal to 30%. The opaque wax also comprises an anionic emulsifier between 3% and 7%, optionally equal to 5%, configured for preventing the aforementioned waxes of different types from remaining separate from each other. One example of an emulsifier suitable for the purpose is SILASTOL R687, commercially distributed by the German company Schill+Seilacher GmbH. The abovementioned opaque wax also comprises distilled water between 25% and 35%, optionally 30%, and silica between 10% and 20%, optionally 15%. The above quantities in percentage by weight of the components of the opaque wax can vary in the ranges indicated above in such a way that their sum is always equal to 100%. Opaque wax has the consistency of an opaque viscous liquid and gives the mixture the ability to make the surface S of the aforementioned leather layer uniform and soft, therefore pleasant to the touch.

The polymeric compound comprising polyurethane of the mixture according to the invention, in the jargon of the sector also called opaque polyurethane, is a polymeric compound with the addition of silica. More specifically, it comprises powdered silica in a percentage weight between 15% and 25%, optionally equal to 20%, acrylic polymers (of any type as long as they are not cationic) in a percentage weight between 25% and 35% , optionally equal to 30%, aliphatic polyurethanes having percentage weight between 15% and 25%, optionally equal to 20%, distilled water of percentage weight between 20% and 30%, optionally equal to 25%, thickeners in percentage weight between 3% and 7%, optionally equal to 5%, for example ADDENSANTE PER COMPOUND marketed by the Italian company TICHEM Sri and, optionally, perfumes. The purpose of using perfumes, in quantities between 0 and 5%, is to make the smell of the polymeric compound comprising polyurethane pleasant, and keep any parasites at distance. The above quantities by percentage weight of the components of the polymeric compound comprising polyurethane can vary in the ranges indicated above so that their sum is always equal to 100%.

The polymeric compound comprising polyurethane in the mixture of the present invention increases the mechanical resistance of leather. It also sanitizes the treated leather layer and increases its softness to touch.

With reference to the graphite-based liquid solution, according to a preferred embodiment of the invention, it comprises a graphite powder in protein binder solution. More particularly, graphite-based liquid solution comprises proteins, for example casein, in percentage weight between 10 % and 20%, optionally equal to 15%, graphite powder in percentage weight between 50 % and 70%, optionally equal to 60%, oils of animal or vegetable origin, optionally already partly emulsified with very small quantities of emulsifier such as the aforementioned Silastol R687, in a percentage weight between 3% and 7%, optionally equal to 5%, distilled water, in percentage weight between 3 % and 8%, optionally equal to 5%, and casein in percentage weight between, between 10 % and 20%, optionally equal to 15%. The above said amounts by percentage weight of said components of said graphite-based liquid solution can vary in said intervals in such a way that their sum is always equal to 100%. The graphite powder also comprises graphite granules, wherein the distribution curve of the dimensions of the granules or Particle Size Distribution (PSD), according to a particularly advantageous embodiment of the invention, can be represented by the following indicators D ¹⁰ = 3-6 micron;

D ⁵⁰ = 10-25 micron;

D ⁹⁰ = 50-70 micron; where D ¹⁰ , D ⁵⁰ and D ⁹⁰ are indicators that represent the values of the diameters of the granules of said graphite powder, for weight percentage of 10%, 50% and 90%, respectively. In other words, the values of the D ¹⁰ , D ⁵⁰ e D ⁹⁰ indices show that 10%, 50% and 90% of the analyzed granules have a diameter lower than the corresponding micron value indicated, i.e. lower than 3-6 microns, lowerthan 10-25 microns and lowerthan 50-70 microns, respectively. The graphitebased liquid solution gives the mixture of present invention the ability to render the treated leather layer more resistant to mechanical stresses and more antibacterial, as will also be seen in the following.

The catalyzing polyaziridine comprises 2-ethyl-2-[[3-(2-methylaziridin-l- yl)propionyl]methyl]propane-l,3-diyl bis(2-methylaziridine-l-propionate) in percentage weight equal to 100%. An example of a polyaziridine catalyst which can be employed in the mixture of the present invention is given by the product NITROFIX 7732 by Chemical S&G s.r.l. it gives the mixture of the present invention the ability to make the treated leather layer more impermeable to water and solvents.

Optionally, the mixture of the present invention can be pigmented and therefore can comprise at least one pigment, for example in an amount by weight between 10 mg and 40 mg, optionally between 15 mg and 35 mg, more optionally between 20 and 30 mg per square meter of surface S of the leather layer to be treated.

According to a preferred variant of the invention, the pigment is a pigment based on Coal powder.

The mixture above can be advantageously used in a treatment method of one leather layer s. Such method, which also forms part of the present invention, is indicated in the enclosed Figures with reference number 1 and comprises at least the following operational steps:

A. covering said at least one surface S of said leather layer with said at least one mixture as above described;

B. drying said at least one surface S of said leather layer;

C. covering again said at least one surface S of said leather layer with said at least one mixture as above described; and

D. drying again said at least one surface S of said leather layer.

According to an advantageous aspect of the invention, step A of method 1 comprises spraying, optionally uniformly, the mixture above on the surface S of said leather layer, with a delivery pressure comprised between 0.5 and 0.8 atmospheres, fora spraying interval comprised between 30 and 50 seconds, optionally equal to 40 seconds. When sprayed, the mixture is at room temperature.

Step B of invention method 1 comprises drying, optionally through steam, at a temperature between 60 and 90°C, optionally comprised between 70 and 80°C, the leather layer on which the mixture has been sprayed. The drying step of the leather layer is carried out for a drying interval comprised between 20 and 40 seconds, optionally equal to 30 seconds.

Step C of invention method 1 is equal to step A while step D of method 1 is equal to step B.

At the end of step D, the leather layer treated with the mixture according to the present invention is completely uniformly covered with it, and shows high characteristics of mechanical resistance and antibacterial characteristics.

According to a preferred embodiment of the invention, steps A to D of method 1 can be performed for a number N of times at least equal to or greater than three, so as to ensure that the surface S of the treated leather layer is completely uniformly covered with mixture. At the end of step D, the treated leather layer can rest for a prefixed rest interval, for example equal to one hour. However, the person skilled in the art will easily understand that the duration of that interval can vary at will, as long as the leather leaving step D reaches room temperature before being subjected again to a cycle A-D or to the subsequent processing steps.

When the mixture used in the method is not pigmented (step DO), at the end of last executed step D, method 1 optionally comprises one traditional dyeing step (step DI) of leather layer surface S, optionally through spraying. The traditional dyeing step is intended to confer the treated leather layer a color different from the typical dark grey color that the mixture according to the invention, with no pigment, would confer thereto. The possible colors are the most varied, as long as they are not white or however too light, depending on the color of the starting leather layer.

With reference to steps A to D described above, it should be noted that they can be performed for example in a known type of leather dyeing station, usually comprising a conveyor belt and two treatment cabins. The conveyor belt is configured to receive the leather layer, which is stretched on the conveyor belt, and to move it between a first treatment cabin, wherein steps A and B of the invention method are carried out underthe above indicated conditions, and a second treatment cabin, wherein steps C and D of the invention method are carried out.

Each treatment cabin can comprise a first working area comprising for example a plurality of, optionally eight, spray guns, configured to deliver the above mixture under pressure, optionally uniformly, and a second working area comprising, for example, a steam oven, wherein the drying of the leather layer covered with mixture takes place.

According to a preferred embodiment of invention method 1 described above, the leather layer is transported through a dyeing station of the type mentioned above for at least three times. Obviously, the dyeing station, which is not the object of the present invention, could be configured also differently and could for example comprise a conveyor belt configured to move the leather layer between six treatment cabins, divided into pairs of two, wherein, steps A to D are carried out in each pair of cabins.

Going back to method 1 of the present invention, this comprises at least carrying out on the leather layer so covered with mixture, at least a first finishing procedure, in order to further fix the mixture of the leather layer (step E). This step of invention method 1 comprises the following sub-steps:

E.l covering the surface S of the leather layer by spraying at least one first nitrocellulose aqueous emulsion, in technical jargon also called nitro-emulsion, wherein the spraying is carried out at a delivery pressure comprised between 0.5 and 0.8 atmospheres, with the first nitrocellulose aqueous emulsion at room temperature, for a spraying interval comprised between 30 and 50 seconds, optionally equal to 40 seconds;

E.2 drying, optionally through steam, the surface S of the leather layer, at a temperature comprised between 60°C and 90°C, optionally comprised between 70°C and 80°C, for a drying interval comprised between 20 and 40 seconds, optionally equal to 30 seconds; and then E.3. repeating sub-step E.l once; and

E.4 repeating sub-step E.2 once.

The first nitrocellulose aqueous emulsion used at method step E comprises, according to a preferred embodiment of the invention:

- distilled water, in an amount by percentage weight between 3% and 7%, optionally equal to 5%;

- nitrocellulose powder, in an amount by percentage weight between 40% and 60%, optionally equal to 50%;

- emulsifiers, of any type suitable to keep the abovesaid nitrocellulose powder into emulsion, in an amount by percentage weight between 3% and 7%, optionally equal to 5%; and

- alcohols, for example ethyl alcohol or isopropyl alcohol, in an amount by percentage weight between 30% and 50%, optionally equal to 40%.

The abovesaid amounts by percentage weight of said components of the first nitrocellulose aqueous emulsion vary within the intervals above, in such a way that their sum is always equal to 100%.

This first aqueous emulsion of nitrocellulose generates on leather a surface that is soft to the touch, has medium brightness and, according to the method of the present invention, can be diluted according to the desired ratios to be applied on the leather layer also at the subsequent steps of the method of the present invention present invention.

Also in this case it should be noted that step E of method 1 can be performed in a known type of leather dyeing station, of the type described above with reference to phases A to D of the invention method. In this case, therefore, step E would involve a single passage of the leather layer inside the dyeing station. It goes without saying that, if the same dyeing station were used both for carrying out steps A to D and for step E, a resting time interval should be foreseen between the last executed method step D and step E, for example comprised between 10 and 30 minutes, optionally equal to 20 minutes, necessary for replacing the mixture according to the invention with the first aqueous emulsion of nitrocellulose, in the dyeing station, and the eventual cleaning of the hydraulic circuit for dispensing them.

The same applies if the same dyeing station was used both for carrying out phases A to D and for traditional dyeing phase DI. A resting time interval should be foreseen between the last executed method step D and step DI, for example between 10 and 30 minutes, optionally equal to 20 minutes, necessary for replacement, in the dyeing station, of the mixture according to the invention with a pigmented mixture and the possible cleaning of the hydraulic circuit for supplying them. Obviously the above remains valid also in the transition between method step DI and step E.

Advantageously, method 1 of the present invention can also comprise the execution on the leather layer, of at least a second finishing procedure, aimed at making it soft to the touch (step F).

This step of method 1 comprises the following sub-steps:

F.l covering the surface S of the leather layer, by spraying at least one second hydro-emulsion, wherein the spraying is carried out at a delivery pressure comprised between 0.5 and 0.8 atmospheres, with the second hydro-emulsion at room temperature, for a spraying interval comprised between 30 and 50 seconds, optionally equal to 40 seconds;

F.2 drying, optionally by steam, the surface S of the said leather layer, at a temperature comprised between 60°C and 90°C, optionally comprised between 70°C and 80°C, for a drying interval comprised between 20 and 40 seconds, optionally equal to 30 seconds;

F.3. repeating once sub-step F.l;

F.4 repeating once sub-step F.2; and

F.5 leaving the so finished leather layer to rest, for at least one hour.

The second hydro-emulsion used in the invention method 1 comprises, according to a preferred embodiment of the invention, per square meter of surface S the leather layer to be finished:

- distilled water, in one amount by weight comprised between 80 mg and 120 mg, optionally comprised between 90 mg and 110 mg, more optionally equal to 100 mg; - one fat touch feel modifier, for example the Modifier n.663 made commercially available by the company Chemical S&G s.r.l., in one amount by weight comprised between 20 mg and 30 mg, optionally comprised between 23 mg and 27 mg, more optionally equal to 25 mg; and

- one silicone-based touch feel modifier, for example the Modifier n.6621 made commercially available by the company Chemical S&G s.r.l., in one amount by weight comprised between 4 mg and 8 mg, optionally comprised between 5 mg and 7 mg, more optionally equal to 6 mg.

The fat touch feel modifier included in the second hydro-emulsion comprises, for example, the following amounts by percentage weight of:

- beeswax between 25% and 35%, optionally equal to 30%,

- corn starch between 15% and 25%, optionally equal to 20%,

- distilled water between 25% and 35%, optionally equal to 30%,

- one emulsifier, for example the aforementioned SILASTOL R687, between 3% and 7%, optionally equal to 5%,

- silicone oil between 10% and 15%, optionally 12%, e

- oils of natural or vegetable origin, between 1% and 5%, optionally equal to 3%, such that their sum is 100%. In other words, the amounts in percentage weight of the components of the fat touch feel modifier can vary in the ranges indicated above, such that their sum is always equal to 100%.

In addition, the fat touch feel modifier can also comprise trace amounts of diethylenetriamine and fatty acids such as tall oil and dequaternized benzyl chlorine.

The fat touch feel modifier gives the leather treated with the second hydro-emulsion a pleasant slippery and powdery feel.

The silicone-based touch feel modifier comprises metalethyl chlorine and silicone alcohol in percentages between 55% and 67% (metalethyl chlorine) and between 45% and 33% (silicone alcohol), respectively. As above, the percentage weight amounts of the components of the silicone-based touch feel modifier can vary within the ranges indicated above, such that their sum is always equal to 100%.

At the end of step E or F the method of the present invention comprises step G of pressing the thus treated and finished leather layer, at a pressure between 35 and 45 atmospheres, optionally equal to 40 atmospheres, at a temperature between 100 and 120 °C, optionally equal to 110°C, for a pressing interval between 1 and 15 seconds, optionally between 2 and 10 seconds. Then, the leather layer is sent to subsequent processing stations for selection, measurement, and packaging.

With the mixture and the treatment method described above, the problems represented in the introduction are solved.

The mixture described above, applied to a leather layer according to the steps of method 1 allows obtaining a leather layer having high standards of antibactericity and mechanical resistance, soft to the touch, in various colors and cheaper, compared to traditional methods that use graphene for the treatment of leather.

With particular reference to the antibacterial properties of the leather layer obtained according to method 1 of the present invention, it is noted that some preliminary laboratory tests were carried out according to the ISO 20743:2013 method "Determination of antibacterial activity of textile products", on a layer S of sheep and goat leather, tanned with chrome according to a traditional method (for example as described in the article "HEAVY METAL CONTENTS OF BOOTEE LEATHERS TANNED WITH DIFFERENT PROCESS RECIPES" by Huseyin Ata KARAVANA et al., TEKSTIL ve KONFEKSIYON 3/2011 , 305-310) and subsequently subjected to the treatment method of the invention, for determining the concentration of microorganisms such as Staphylococcus aureus and Klebsiella pneumoniae contained therein.

The measurements were performed both on the grain side and on the split side of the tested leather layer and the results thereby obtained were compared with the concentrations of these bacteria in a reference sample of leather having the same origin (sheep and goat), subjected to the same chrome tanning treatment but not to the subsequent invention treatment method.

The specifications of the preliminary tests, conducted according to the abovementioned ISO 20743:2013 method, can be summarized as follows:

• Bacteria of interest: Staphylococcus aureus ATCC 6538, Klebsiella pneumoniae ATCC 4352

• Inoculum: 0.2 mL of bacterial suspension, 1 x 10 ⁵ CFU/mL diluted in nutrient broth.

• Contact time: 24 hours at 37° C.

• Type of measurement: Plate count method.

• Neutralizer: 20 ml.

The summary table of Figure 4 shows, for the reference sample and the two leather samples obtained from layer S of sheep and goat tanned according to the aforementioned traditional method and then subjected to the treatment of the invention (grain side and split side), all having the same thickness between 0.9 mm and 1.1 mm, the antibacterial activity (A) determined according to relationship:

A = (logCt — logCo) - (logTt - logCo) where:

C _t = average value of the number of bacteria obtained from reference sample, after 24 hours of contact.

Co = average value of the number of bacteria obtained from reference sample immediately after inoculation.

T _t = average value of the number of bacteria recovered from the sample, after 24 hours of contact.

As can be seen, both leather samples tested 24 hours after inoculation show greater antibacterial activity (A) than the reference sample.

In particular, the increase in the antibacterial properties of the tested leather samples (both from the grain side and from the split side) treated with the method of the present invention, compared to the reference sample, was between about 12% and 33% for Staphylococcus aureus ATCC 6538.

For Klebsiella pneumoniae ATCC 4352, the increase in antibacterial properties of the tested skin samples, treated with the method of the present invention and compared to the reference sample, was even more significant. In fact, for the sample tested on the grain side, the antibactericity increase was between about 49% and 74%, while in the sample tested on the split side, the antibactericity increase was between about 54% and 80%.

In the above, the preferred embodiments have been described and variations of the present invention have been suggested as defined by the appended claims.