WO2011026936A2

WO2011026936A2 - Natural stones coated with a protective layer, process for their production and their use

Info

Publication number: WO2011026936A2
Application number: PCT/EP2010/062948
Authority: WO
Inventors: Luciano Babbini; Nicoletta De Vietro; Francesco Fracassi; Riccardo D'agostino
Original assignee: Luciano Babbini; Nicoletta De Vietro; Francesco Fracassi; D Agostino Riccardo
Priority date: 2009-09-03
Filing date: 2010-09-03
Publication date: 2011-03-10
Also published as: ITFI20090192A1; WO2011026936A3

Abstract

There are described natural stones (i.e. granites, marbles, travertines, etc.) commonly used for cladding/decorative purposes in the building sector, the surface of which is coated with a superhydrophobic protective layer obtained by superimposing a film with chemical composition Si_yO_x and a Teflon-like film, both deposited using plasmochemical techniques. There are also described the processes and the plasma reactors used for their production.

Description

NATURAL STONES COATED WITH A PROTECTIVE LAYER, PROCESS FOR THEIR PRODUCTION AND THEIR USE

Field of the invention:

The present invention relates to the field of processes aimed at protecting the surfaces of natural stones commonly used for cladding/decorative purposes in the building sector. Background art:

The increasing use, particularly in the technical building sector, of natural stone such as marbles and granites, travertines, etc., for functional applications such as kitchen countertops, sanitary ware finishes, flooring, important parts of the interior furnishings and of the external part of a building, is known.

It is also known that the use of these materials, of great prestige and aesthetic effect, is substantially limited by wear and corrosion to which they are subject in time. In fact, the materials in question deteriorate in time for various reasons, such as:

- wear. The action of abrasive powders, of walking and/or rubbing causes, for example, consumption of the surfaces of floors or pavements;

- corrosion caused by atmospheric agents and/or contact with corrosive acid substances: for example, lemon juice, typical substance able to irreversibly corrode a stone material (i.e. marbles, granites) if used as kitchen countertops.

- the staining action exerted by oily and non-oily substances; stone materials are extremely porous and, therefore, irreversibly absorb liquid or semi-solid oily (i.e. olive oil, mayonnaise, milk, etc.) or non-oily (i.e. ink, tea, coffee, tomato juice, coca cola, fruit juices, etc.) substances with which they come into contact.

Therefore, it is known that the surface of the natural stones, when used for cladding/decorative purposes in the building sector, is subjected to mechanical finishing treatments such as smoothing/polishing/flaming and the like and/or to the application of layers of synthetic material, in order to prolong the useful life of the materials in question. However, these techniques have always provided somewhat unsatisfactory results, particularly with regard to preservation in time of the appearance and functional characteristics of the finished product.

Plasma deposition of thin films, generally indicated with the acronym PE-CVD (Plasma Enhanced - Chemical Vapour Deposition) and substantially consisting in the use of a cold plasma to deposit, in vacuum conditions, a thin film on the surface of the substrate to be coated, and the plasmochemical treatment (grafting of functional groups, cross-linking and/or ablation), have proved to be extremely versatile technologies to change the surface characteristics of conventional materials, providing them with particular performances and properties.

The patent application PCT/IB2008/000926 describes slabs of flat stone material protected by a transparent film with chemical composition Si_yO_x deposited using a plasmochemical process, using as precursor tetraethoxysilane (TEOS) mixed with oxygen or oxygen/argon. However, films with the composition Si_yO_x deposited using the plasma process are known to grow on the surface of materials on which they are deposited, following their morphology and consequently do not block any pores, thereby allowing penetration of water and, consequently crumbling of the substrate, and therefore even this solution is not fully satisfactory to truly protect the stone in the long term.

Therefore, the importance of providing a process that is able to provide stone surfaces with the desired protection is evident.

Brief description of the figures:

Fig. 1 schematically shows a plasmochemical reactor for treatment of natural stone surfaces used for cladding/decorative purposes in the building sector (i.e.,. stone materials, travertines, etc.) according to the invention.

Fig. 2 schematically shows a slab or flat component of natural stone used for cladding/decorative purposes in the building sector (stone materials, travertines, etc.) protected according to the present invention.

Summary of the invention

There are described stone surfaces coated by a superhydrophobic protective layer obtained by superimposing a film with chemical composition Si_yO_x and a Teflon-like film, both deposited using plasmochemical techniques and the process for their production.

Detailed description of the invention

The present invention allows the aforesaid problems to be overcome, allowing long-term protection of the surface of natural stone materials used for cladding/decorative purposes against mechanical wear, against the corrosive action caused by acid substances and against stains caused by contact with oily and non-oily substances.

According to the present invention, with the term natural stone material used as cladding is intended all the natural stones as, for example: marbles, granites, travertines, ceramics, etc., used for cladding and hereinafter these will be indicated simply as "slabs" or "products" without specific reference to the use that is given to this term in the technical sector of reference.

The stones protected according to the invention have on their surface a protective coating composed of hard and compact protective barrier film, with chemical composition Si_yO_x, where y can vary between 0.95 and 1.15 and x can vary between 1.5 and 2.05, coated with a superhydrophobic thin film in Teflon-like material.

The protective film is deposited on the surface of the stone to be treated using gas of silicon-based compounds (SiH₄, etc.) or vapours of liquid/solid organosilane compounds, such as tetraethoxysilane (TEOS), vinyltrimethylsilane (VTMS), silicon-based oils, and the like mixed with oxygen, argon or oxygen/argon. The protective film has a thickness generally between 1 and 5 μιη.

The superhydrophobic thin film in Teflon-like material is instead obtained by using plasmas fed by fluorinated gases, on their own or mixed with argon, such as: hexafluoropropene, perfluorocyclobutane, etc., and is for example a fluorinated hydrocarbon like C₃F₆, C₄F₈ etc; this film has a thickness normally comprised between 10 and 50 nm in order to obtain properties of resistance to acid attack (for example in the case of lemon juice, vinegar, etc.), to oily (oil, mayonnaise, milk, chocolate, etc.) or non-oily (ink, coffee, tea, ketchup, etc.) stains and to mechanical wear.

Preferably the deposition process of the protective coating is preceded by a first step of activation of the surface of the sample to be treated in argon, oxygen, argon/oxygen, hydrogen, argon/hydrogen plasma, according to the natural stone to be protected.

Moreover, the aforesaid coating is perfectly transparent and therefore does not alter the aesthetic properties of the stone on which it is deposited.

To obtain the protective layers, and also for any initial activation of the slab to be treated, according to the invention customary plasmochemical reactors of the type represented schematically in Fig. 1 are used.

As shown in Fig. 1, the plasmochemical reactor 100 used for plasmochemical treatment of slabs 10 is substantially composed of a single reaction chamber 110, connected to the feed and control equipment, such as:

- vacuum forming devices 120;

- system for reading the pressure inside the reaction chamber 130; - radiofrequency generator (RF, 13.56 MHz) 140;

- matching network 150;

- devices 160 to feed reagents in gaseous or vapour state to the reaction chamber 110;

- a flat electrode 170, connected to the radiofrequency generator, disposed inside the reaction chamber 110;

- a flat (ground) electrode 180, disposed inside the reaction chamber 110, on which the element in stone material used for cladding/decorative purposes in the building sector is placed to be coated.

According to the invention, the process for the preparation of the stone material with surface protection involves the following steps:

a) providing a natural stone slab 10 or component used for cladding/decorative purposes in the building sector 10 with finished, clean, washed and de greased surface;

b) placing the slab 10 in the reaction chamber 110;

c) forming a process vacuum in the reaction chamber 110;

d) performing, inside the reaction chamber 110, a pre-treatment (etching) step of the surface of the slab 10 to be coated;

e) forming a process vacuum in the reaction chamber 110;

f) simultaneously feeding reagents to the reaction chamber and ignition of the plasma; g) plasmochemical deposition of the film 20 with chemical composition Si_yO_x for a programmed time interval;

h) forming a process vacuum in the reaction chamber 110;

i) plasmochemical deposition of the film 30 with Teflon-like chemical composition for a programmed time interval;

j) forming a process vacuum in the reaction chamber 110;

k) switching off the pumping system 120 and allowing air to enter;

1) removing the finished slab 10.

According to a particularly preferred embodiment, the process according to the invention provides that:

a) the activation step of the surface of the slab 10 is performed in the following conditions: - pressure comprised between 10^"3 and 10° torr;

- power density (at 13.56 MHz) comprised between 0.06 and 1.00 W/cm ; - flow of argon, oxygen, argon/oxygen, hydrogen, argon/hydrogen comprised between 0 and 4000 seem (standard cubic centimetres per minute),

- treatment comprised between 30 seconds and 20 minutes.

b) The deposition step of the film with chemical composition Si_yO_x 20, on the surface of the slab 10, is performed in the following conditions:

-3 0

- pressure comprised between 10^" and 10 torr;

- power density (at 13.56 MHz) comprised between 0.1 and 8 W/cm ;

- flow of the plasma feed gases:

organosilane precursor comprised between 3 and 9000 seem, oxygen comprised between 0 and 9000 seem, argon comprised between 0 and 5000 seem.

The plasmochemical deposition time varies in relation to the characteristics required to be obtained for the finished product and, therefore, to the thickness of the protective coating to be deposited. In particular, a time comprised between 5 and 60 minutes is estimated for the deposit of up to 3 μιη of film with chemical composition Si_yO_x.

c) The plasmochemical deposition process of the film with Teflon-like chemical composition 30 is performed in the following conditions:

- pressure comprised between 10 -^"3 and 100 torr;

- power density (at 13.56 MHz) comprised between 0.03 and 2 W/cm ;

- flow of fluorinated gas comprised between 10 and 7000,

- flow of argon comprised between 0 and 1000 seem,

- treatment time comprised between 10 seconds and 10 minutes.

The deposition of a film with thickness around 50 nm requires an average time of around 30 seconds.

Naturally, in place of a system composed of a single reaction chamber, operating discontinuously as describe above, the process according to the invention can be performed continuously using a system provided with up to five distinct chambers, namely:

- a chamber for loading the marble slabs;

- a chamber for the activation process of the natural stone used for cladding/decorative purposes in the building sector (i.e. marbles, granites, travertines);

- a chamber for plasmochemical deposition of the film with chemical composition Si_yO_x;

- a chamber for deposition of the film with Teflon-like chemical composition;

- a chamber for unloading the finished slabs. The relative auxiliary devices will, in this case, be adapted to the enlarged configuration of the system, while the ranges relative to the values of the operating parameters described above will remain unchanged.

Experimental tests described below have proved that the surface of the natural stones used for cladding/decorative purposes in the building sector, in particular marbles and granites, coated with the protective film described, offers considerable resistance to mechanical wear, to corrosion caused by acids and to oily and non-oily stains, that lasts for long periods of time.

Moreover, the coatings in question are completely transparent and therefore do not alter the decorative characteristics of the material treated.

It is noted how the application of the Teflon-like layer allows elimination of the argon plasma cross-linking process, described in the aforesaid patent, as it is able to coat the underlying Si_yO_x film in a compact and uniform manner, so as to completely seal the porosities of the natural stone, in particular marble and granite, to which it is applied.

The surface of a stone material, coated according to the process described below and subjected for 12 months to the action of atmospheric agents, in fact shows no signs of crumbling and its capacities of resistance to acids and to oily and non-oily stains remain unchanged. This result was achieved following the operating methods described below. The examples below were performed on substrates with a thickness comprised between 0.5 and 3 cm. However, the process described can of course be applied to slabs and natural stone components of any shape and dimension, naturally when the dimensions of the chamber or chambers and, in proportion thereto, all the auxiliary devices and experimental parameters, are appropriately scaled.

EXAMPLE 1: LONG-TERM RESISTANCE TEST: CRUMBLING TESTS IN WATER Without doubt, water can be considered the main cause of crumbling of porous natural stones, such as marbles, used for cladding/decorative purposes in the building sector. In fact, the porous structure of these substrates facilitates water penetration, which transforms the stone material into soluble carbonate.

Part of the surface of a sample of slab of white Carrara marble, taken as material representing the whole class of porous materials used for cladding/decorative purposes in the building sector, was protected with metal adhesive tape. The surface of the portion of the sample not covered by the metal adhesive tape was modified, in the plasmochemical reactor, in the following experimental conditions:

Activation

Pressure = 10^" torr

Power density = 0.2 W/cm²

Ar = 20 seem

Treatment time = 5 minutes

Plasmochemical deposition of the film with chemical composition Si_yO_x

Pressure: 10^" torr

Power density = 2.5 W/cm²

Ar = 44 seem

C"₂ = 90 seem

TEOS = 4 seem

Deposition time = 30 minutes (thickness of the film deposited = 3 μιη)

Plasmochemical deposition of the film with Teflon-like chemical composition

Pressure: 10^"1 torr

Power density = 0.3 W/cm

Ar = 3 seem

C₃F₆ = 30 seem

Deposition time = 30 seconds (thickness of the film deposited = 50 nm)

At the end of the process, after having removed the protective tape, the stone sample was covered with water for 12 hours. After this period of time, it was ascertained that water wets the untreated surface of the sample (the strip previously covered by the adhesive tape appears "shinier") to a much greater extent than the part of surface modified by the plasmochemical process.

Subsequently, resistance over time of the protective coating deposited in the aforesaid experimental conditions was assessed, in real conditions.

Specifically, the samples of natural stone, obtained following the experimental procedure described above, were exposed to atmospheric agents (rain, wind, etc.) for 12 months. After this period of time, the surface of the stone samples was observed under the electronic microscope, excluding both the presence of crumbling areas of the substrate, and of cracks and/or areas of detachment of the film from the surface of the stone material in question, as well as any other form of alteration of the protective coating.

EXAMPLE 2: ASSESSMENT OF IRIDESCENCE AND OF TRANSPARENCY

The surface of a slab of white Carrara marble, taken as material representing the whole class of natural stone materials used for cladding/decorative purposes in the building sector, was modified in the following experimental conditions:

Activation

Pressure = 10^" torr

Power density = 0.2 W/cm

Ar = 20 seem

Treatment time = 5 minutes

Plasmochemical deposition of the film with chemical composition Si_yO_x

Pressure: 3*10^" torr

Power density = 2.5 W/cm

Ar = 44 seem

0₂ = 640 seem

Silicon oil = 150 seem

Deposition time = 10 minutes (thickness of the film deposited = 3 μιη)

Plasmochemical deposition of the film with Teflon-like chemical composition

Pressure: 10^"1 torr

Power density = 0.3 W/cm

Ar = 3 seem

C₃F₆ = 30 seem

Deposition time = 30 seconds (thickness of the film deposited = 50 nm)

At the end of the plasmochemical treatment, the film deposited on the surface of the stone sample met the need for absence of iridescence and for transparency, required for the expected uses.

EXAMPLE 3: CORROSION TEST: ASSESSMENT OF RESISTANCE TO LEMON JUICE AND VINEGAR

As it is known, nothing is more corrosive than lemon juice and vinegar for a kitchen countertop produced with a porous material (i.e. marble). Therefore, this test is without doubt discriminating in order to judge the resistance to acids of the surface of the material in question.

A slab of white Carrara marble, taken as material representing the whole class of natural stone materials used for cladding/decorative purposes in the building sector, was modified using the plasmochemical process in the following experimental conditions:

Activation

Pressure = 10^" torr

Power density = 0.2 W/cm

Ar = 20 seem

Treatment time = 5 minutes

Plasmochemical deposition of the film with chemical composition Si_yO_x

Pressure: 10^" torr

Power density = 5 W/cm

Ar = 30 seem

0₂ = 100 seem

HMDSO = 7 seem

Deposition time = 40 minutes (thickness of the film deposited = 3 μιη)

Plasmochemical deposition of the film with Teflon-like chemical composition

Pressure: 10^"1 torr

Power density = 0.3 W/cm²

Ar = 15 seem

Deposition time = 60 seconds (thickness of the film deposited = 50 nm)

A drop of lemon juice and a drop of vinegar were deposited on the surface of the aforesaid sample. After 30 minutes of contact, the surface of the stone material in question was rinsed with water and dried. At the end of these operations there were no signs of corrosion on the surface of the substrate in question. On the other hand, the stone material as is was irreparably corroded both by the lemon juice and by the vinegar, after two seconds of contact.

On the basis of the experimental results described above, it was possible to conclude that the protective film, deposited in the experimental conditions described above, is able to guarantee sufficient resistance to acidity (i.e. for a kitchen countertop, on which the operation can be performed in a short time) of up to 30 minutes. Finally, films of greater thickness will presumably be able to protect the surface of the material considered from corrosion caused, for example, by lemon juice and by vinegar, for longer times.

EXAMPLE 4: TEST FOR RESISTANCE TO OILY STAINS: ASSESSMENT OF RESISTANCE TO OLIVE OIL, MAYONNAISE AND MILK

Activation

Pressure = 10^~2 torr

Power density = 0.2 W/cm

Ar = 20 seem

Treatment time = 5 minutes

Plasmochemical deposition of the film with chemical composition Si_yO_x

Pressure: 10^~2 torr

Power density = 4 W/cm

Ar = 40 seem

0₂ = 200 seem

VTMS = 8 seem

Deposition time = 15 minutes (thickness of the film deposited = 3 μιη)

Plasmochemical deposition of the film with Teflon-like chemical composition

Pressure: 10^"1 torr

Power density = 0.3 W/cm

Ar = 15 seem

C₄F₈ = 50 seem

Deposition time = 60 seconds (thickness of the film deposited = 50 nm)

A drop of olive oil, a drop of mayonnaise and a drop of milk were deposited on the surface of the aforesaid sample. After 30 minutes of contact, the surface of the sample in question was rinsed with water and dried. At the end of these operations no stains were detected on the surface of the substrate in question. On the other hand, the stone material as is was irreparably stained at most after two minutes of contact with all the substances being examined . On the basis of the experimental results described above, it was possible to conclude that the protective film, deposited in the experimental conditions described above, is able to guarantee sufficient resistance to oily stains (i.e. for a kitchen countertop, on which the operation can be performed in a short time) of up to 30 minutes.

Finally, films of greater thickness will presumably be able to protect the surface of the material considered from stains caused by oily substances, such as, by way of example, olive oil, mayonnaise and milk, for longer times.

EXAMPLE 5: RESISTANCE TEST TO NON-OILY STAINS: ASSESSMENT OF

RESISTANCE TO INK, COCA COLA, TEA, COFFEE, KETCHUP AND FRUIT JUICE A slab of white Carrara marble, taken as material representing the whole class of natural stone materials used for cladding/decorative purposes in the building sector, was modified using the plasmochemical process in the following experimental conditions:

Activation

Pressure = 10^" torr

Power density = 0.2 W/cm²

Ar = 20 seem

Treatment time = 5 minutes

Plasmochemical deposition of the film with chemical composition Si_yO_x

Pressure: 4*10^" torr

Power density = 6 W/cm²

Ar = 10 seem

0₂ = 150 seem

VTMS = 12 seem

Deposition time = 15 minutes (thickness of the film deposited = 3 μιη)

Plasmochemical deposition of the film with Teflon-like chemical composition

Pressure: 10^"1 torr

Power density = 0.3 W/cm

Ar = 15 seem

C₄F₈ = 50 seem

Deposition time = 60 seconds (thickness of the film deposited = 50 nm)

A drop of ink, a drop of coca cola, a drop of tea, a drop of ketchup, a drop of fruit juice and a drop of coffee were deposited on the surface of the aforesaid sample. After 30 minutes of contact, the surface of the sample in question was rinsed with water and dried. At the end of these operations no stains were detected on the surface of the substrate in question. On the other hand, the stone material as is was irreparably stained after a few seconds of contact with all the substances being examined .

On the basis of the experimental results described above, it was possible to conclude that the protective film, deposited in the experimental conditions described above, is able to guarantee sufficient resistance to non-oily stains of up to 30 minutes. Finally, films of greater thickness will presumably be able to protect the surface of the material considered from stains caused by non-oily substances, such as, by way of example, ink, coca cola, tea, coffee, fruit juice and ketchup, for longer times.

EXAMPLE 6: MECHANICAL WEAR TEST: TRIBOLOGICAL ANALYSIS

Some samples of slab of white Carrara marble, taken as material representing the whole class of natural stone materials used for cladding/decorative purposes in the building sector, were modified using the plasmochemical process in the following experimental conditions:

Activation

Pressure = 10^" torr

Power density = 0.2 W/cm

Ar = 20 seem

Treatment time = 5 minutes

Plasmochemical deposition of the film with chemical composition Si_yO_x

Pressure: 4.5*10^" torr

Power density = 0.6 W/cm

0₂ = 800 seem

Silicon oil = 600 seem

Deposition time = 10 minutes (thickness of the film deposited = 3.5 μιη)

Plasmochemical deposition of the film with Teflon-like chemical composition

Pressure: 10^"1 torr

Power density = 0.3 W/cm

Ar = 3 seem

C₃F₆ = 30 seem

Deposition time = 30 seconds (thickness of the film deposited = 50 nm) The samples thus obtained were subsequently subjected to tribological tests aimed at determining the friction coefficient, assumed as magnitude representing the surface hardness of the substrate. The tests performed showed that a slab covered with the coating, deposited in the experimental conditions described, has a greater relative surface hardness than that of the surface of the stone material in question as is.

Therefore, the process described allows flat elements (slabs or components) of natural stone material used for covering/ decoration in the building sector (i.e. marbles, granites, travertines, etc.) to be produced in a precise, safe and reliable manner with the surface coated in a long-lasting superhydrophobic protective layer, which improves the characteristics of surface resistance to acids, to oily and non-oily substances and to mechanical wear, without altering its ornamental properties.

The slabs and components of material, obtained following the aforesaid process, can therefore be used potentially for various functional purposes.

Moreover, the process in question, allows all sides and edges of a flat element exposed to the plasma to be coated.

Finally, the treatment can be applied to elements whose surface has been finished with mechanical processes of known type.

Claims

1. Slab of stone wherein at least a surface, or a portion thereof, presents a protective layer consisting of two superimposed films deposited by plasma techniques using, in sequence, cold plasmas fed by mixtures of organosilane compounds, oxygen and/or argon and mixtures of fluorinated gases and argon.

2. Slab according to claim 1 wherein said slab of stone is a natural stone.

3. Slab according to claims 1 - 2 wherein said protective layer consists of superimposing to a film with chemical composition Si_yO_x, wherein y is comprised between 0.95 and 1.15 and x is comprised between 1.5 and 2.05, a film with a Teflon-like chemical composition.

4. Slab of stone according to claim 3 wherein said Si_yO_x film has a thickness comprised between 1 and 5μιη.

5. Process for the preparation of slab of stone according to claims 1-4, wherein:

- a slab or a component of natural stone with surface finished, clean, washed and degreased is placed in the reaction chamber of the plasmochemical reactor in which a vacuum is formed;

- the slab is subjected to "etching" activation of the surface to be coated with the protective coating;

- the initial vacuum condition present in the reaction chamber is restored;

- the reagents required for deposition of the film with chemical composition Si_yO_x are fed simultaneously into the reaction chamber and the plasma is ignited;

- plasmochemical deposition of the film with chemical composition Si_yO_x is performed for a programmed time interval;

- the vacuum is restored in the reaction chamber;

- the reagents required for deposition of the film with Teflon-like chemical composition are fed simultaneously into the reaction chamber and the plasma is ignited;

- plasmochemical deposition of the film with Teflon-like chemical composition is performed for a programmed time interval;

- gas feed is interrupted;

- the vacuum is restored in the reaction chamber;

- the pumping system is switched off and air is introduced into the chamber;

- the slab of finished stone material is removed.

6. Process according to claim 5 wherein the activation phase is performed in the following experimental conditions:

-3 0

- pressure comprised between 10^" and 10 torr;

- power density (at 13.56 MHz) comprised between 0.06 and 1.00 W/cm ;

- flow of argon, oxygen, argon/oxygen, hydrogen, hydrogen/argon comprised between 10 and 400 seem;

- treatment time comprised between 30 seconds and 20 minutes.

7. Plasmochemical process according to claim 5 wherein the phase of deposition of the film with chemical composition SiyO_x film is performed in the following experimental conditions:

-3 0

- pressure comprised between 10^" and 10 torr;

- power density (at 13.56 MHz) comprised between 0.1 and 8 W/cm ;

- flow of the plasma feed gases:

- flow of the vapour of the organosilane precursor comprised between 3 and 7000 seem, - oxygen comprised between 0 and 7000 seem,

- argon comprised between 0 and 1000 seem.

8. Plasmochemical process according to claim 5 wherein the deposition step of the film with Teflon-like chemical composition is performed in the following experimental conditions:

- pressure comprised between 10^"3and 10° torr;

- power density (at 13.56 MHz) comprised between 0.03 and 2 W/cm ;

- flow of fluorinated gas comprised between 10 and 4000 seem,

- treatment time comprised between 10 seconds and 10 minutes.

9. Plasmochemical reactor for implementation of the process according to claims 5 - 8 comprising: a single reaction chamber for the activation and deposition processes, vacuum forming devices, a radiofrequency generator (RF, 13.56 MHz), a matching network, devices to feed reagents in gaseous or vapour state, a flat electrode, linked to the radiofrequency generator and placed in the reaction chamber, a flat ground electrode, disposed in the reaction chamber, on which the stone element to be coated is placed.

10. Plasmochemical reactor for implementation of the process according to claims 5 - 8 comprising at least 3 distinct reaction chambers, respectively dedicated to activation of the surface of the natural stone, deposition of the film with chemical composition Si_yO_x and deposition of the film with Teflon-like composition, and optionally two chambers dedicated to loading and unloading the stone substrate.