WO2011070293A1

WO2011070293A1 - Hydrophobic substrate including double priming

Info

Publication number: WO2011070293A1
Application number: PCT/FR2010/052641
Authority: WO
Inventors: Frédéric CLABAU; Stéphanie CAPDEVILLE; Martin Melcher
Original assignee: Saint-Gobain Glass France
Priority date: 2009-12-10
Filing date: 2010-12-08
Publication date: 2011-06-16
Also published as: EP2509923A1; CN102666412B; PT2509923E; FR2953823A1; KR20120101678A; CN102666412A; EP2509923B1; ES2542204T3; FR2953823B1; PL2509923T3

Abstract

The invention relates to a glass, ceramic, or glass/ceramic, but preferably glass substrate coated with a hydrophobic coating, said substrate including: a first silicon dioxide SiO₂ priming layer that optionally includes an element from the group formed of Al, B, C, Zr, the density of said layer being at least 1.9 g/cm³ and preferably at least 2.0 g/cm³; and a second priming layer that includes Si-R³-Si groupings, R³being selected from within the group formed of straight, branched, or aromatic, but preferably straight alkyl chains wherein the number of carbons establishing the bond between the two silicon atoms is less than 6 and preferably between 1 and 4 inclusive. Said substrate moreover includes a coating layer that has hydrophobic properties bonded with said priming layer, and includes fluorinated groupings.

Description

The present invention relates to a hydrophobic substrate, in particular consisting of a glass material, a ceramic, a glass-ceramic and so on. The glazings according to the invention are preferably glass panes. They are used, in particular, in the aeronautical, railway or automobile field. They can also be used in the field of building or in the field of interior design such as, for example, decorative panels, furniture, appliances (doors of refrigerators or ovens, showcases) and so on.

This type of treatment aims in a known manner to give the substrate the character of non-wettability, called anti-rain in some areas.

Wettability refers to the property that polar or nonpolar liquids adhere to the substrate forming a film. This adhesion is also valid for dust or dirt of all kinds (fingerprints, insects, etc.). The presence of water and / or dirt is troublesome, in particular for a transparent substrate of the glazing type, in particular used in the field of transport.

The property of non-wettability of a substrate, more commonly referred to as hydrophobicity, is characterized by a contact angle between water and this high substrate. In known manner, the contact angle, when a drop of water is deposited on a flat solid surface, is defined as the angle formed between the tangent to the drop at the point of contact and said solid surface. In the context of the present invention, the substrate is considered to have hydrophobic properties when said contact angle is initially greater than 90 °, preferably greater than 100 °.

When the substrate has such hydrophobicity properties, the liquid then has a tendency to flow easily, in the form of drops, on the substrate, by simple gravity if the substrate is inclined, or under the effect of aerodynamic forces in the case of a moving vehicle. Agents known to give this hydrophobicity property are, for example, fluorinated alkylsilanes as described in the patent applications EP 0 492 417, EP 0 492 545 and EP 0 672 779. According to these documents, the hydrophobic layer can be obtained by applying to the surface of a substrate a solution containing fluorinated organosilanes in an organic solvent. As an organic solvent, EP 0 492 545 cites, in particular, n-hexadecane, toluene, xylene, etc. These solvents are particularly suitable for a fluorinated chlorosilane. It is also possible, according to this document, to use a methyl or ethyl alcohol as a solvent.

Common hydrophobic agents are, in particular, alkylsilanes whose alkyl group has at least one perfluorinated end, that is to say consisting of a group F3C- (CF2) _n -, in which n is a positive integer or no.

One of the most acute problems in the field of the invention is first of all that of the abrasion of the hydrophobic coating. This abrasion occurs more or less during the cleaning operations of the substrate, periodically essential in particular to restore a satisfactory vision through a transparent substrate. It is thus constantly sought to slow down the gradual elimination of hydrophobic coatings of the aforementioned types, which occurs in particular under the action of soot-glazes in the case of an automobile windshield. Such removal may also result from degradation by ultraviolet radiation or hydrolytic attacks.

It is known from the aforementioned EP 0 492 545 A2 application to increase the adhesion of the hydrophobic coating by subjecting the substrate to a priming treatment before applying the coating. This treatment consists in forming a thin intermediate layer from priming or primary agents, which are silicon compounds having at least two hydrolysable functions. In a well-known manner, one of the two hydrolysable functions allows the chemical bonding to the substrate by an oxygen atom bonded to the silicon atom, the second hydrolytic function allowing the attachment of the hydrophobic agent. The compounds SiC, SiHCl 3, SiH 2 Cl 2 and Cl- (SiCl 2 O) _n SiCl 3 are mentioned in application EP 0 492 545 A2 as priming agents, n being an integer between 1 and 4.

Patent EP 944 687 more particularly describes liquid-developed rain coatings and comprising an underlayer or priming layer obtained from a precursor of the Si (OEt) ₄ or SiCl _{4 type} and a functional layer based on perfluoroalkylsilane.

In order to further improve the hydrolytic resistance properties of the hydrophobic coating, EP 1 102 825 discloses a composition for a hydrophobic coating incorporating in the same layer both a fluorinated alkylsilane and a bis-silane.

The application WO 2007/012779 alternately describes a hydrophobic coating consisting of a first bis-silane priming layer and a layer with hydrophobic properties incorporating a fluorinated alkylsilane.

If such coatings can achieve performance in accordance with the vast majority of current UV and mechanical specifications, their chemical inertness is still too low and therefore currently a factor limiting their expansion. In particular, it is necessary that their resistance to saline corrosion be further improved, in particular to enable them to meet the ever more stringent specifications demanded by car manufacturers.

In particular, the tests conducted by the applicant have shown that in the majority of cases, such coatings had difficulty fulfilling the specifications imposed on the subject by automobile manufacturers, as measured in particular by the Neutral Salt Brine (BSN) resistance test according to the NF ISO 9227 standard. Thus, the coatings described in applications EP 944 687 and EP 1,102,825, whose UV resistance performance and mechanical strength have appeared satisfactory, have insufficient performance in saline corrosion, as measured by the BSN test. This insufficiency could limit their development, especially in the Asian market where standards are the most stringent in this area.

The main subject of the present invention is thus coatings resistant not only to abrasion and to UV radiation but also having a high chemical inertia, ie a chemical inertia that enables them to fulfill the specifications imposed on them. currently the automotive industry, especially in terms of salt corrosion. It should be noted that the substrates comprising the coatings according to the invention have performances substantially equal to or greater than those of the hydrophobic substrates known at this date with regard to the other specifications necessary for their different uses, in particular the initial properties of hydrophobicity, mechanical strength or UV resistance.

More specifically, the present invention relates first of all to a process for obtaining a hydrophobic coating on a glass, ceramic, or glass-ceramic substrate, preferably glass, said method being characterized in that it comprises:

a) a first step of depositing on said substrate a first priming layer of the material S1O2 optionally comprising an element of the group consisting of Al, B, C or Zr, the density of said layer being at least 1.9 g / cm ³ and preferably at least 2.0 g / cm ³ ,

b) a second step of applying on said dense priming layer a second priming layer obtained from a bis-silane type priming agent and of formula:

in which

- If is silicon;

R ³ represents a linear, branched or aromatic, preferably linear, carbon chain in which the number of carbons establishing the bond between the two silicon atoms is less than 6 and preferably is between 1 and 4, inclusive;

- R ¹ and R ² each represent an alkyl group or a hydrogen atom;

X ¹ and X ² are hydrolyzable groups, especially chosen from -Cl, -OCH 3 or -OC 2 H 5; preferably X ¹ and X ² are -OC ² H 5,

q and q 'are equal to 0 or 1, and preferably are zero

c) a step of depositing on said second layer a coating with hydrophobic properties and comprising fluorinated groups.

For example, the first layer of S102 may comprise between 1 and 10 mol% of Al.

According to the invention, the first dense priming layer may be deposited by any technique known for this purpose, including magnetron techniques, thermal CVD type deposition techniques, PE-CVD or vacuum or atmospheric plasma. Other techniques are of course possible, provided that they allow the deposition of a sufficiently dense layer in the sense of the present invention. Optionally, the dense sub-layer may according to the invention also undergo an etching operation to increase the roughness, according to the principles described in WO 2005/084943, in particular for obtaining an RMS roughness of said layer between 1 and 30 nm.

According to a mode of the invention, the hydrophobic coating comprises or consists of at least one fluorinated alkylsilane.

For example, the step of depositing the hydrophobic coating is placed implemented from a solution comprising a perfluoroalkylsilane of formula:

F ₃ C- (CF ₂ ) _m - (CH ₂ ) _n - Si (X) _3.p (R) _p in which:

m = 0 to 15, preferably 3 to 7;

n = 1 to 5, preferably n = 2

p = 0, 1 or 2, preferably 0 or 1, very preferably 0;

R is an alkyl group or a hydrogen atom; and

X is a hydrolyzable group such as a halide group or an alkoxy group.

The invention also relates to a glass, ceramic, vitroceramic, preferably glass, substrate that can be obtained by the process described above.

Said substrate is coated with a hydrophobic coating, said coating comprising three layers:

a first priming layer of the material S1O2 optionally comprising a member of the group consisting of Al, B, C or Zr, the density of said layer being at least ^1.9 g / cm ³ and preferably at least 2 0 g / cm ³ directly applied to said substrate,

a second priming layer, directly applied to the first priming layer, comprising Si-R ³ -Si groups, R ³ being chosen from the group consisting of linear, branched, or aromatic, preferably linear, alkyl chains in in which the number of carbons establishing the bond between the two silicon atoms is less than 6 and preferably is between 1 and 4, inclusive limits,

a coating layer with hydrophobic properties in connection with said priming layer, comprising fluorinated groups. By the number of carbons establishing the bond between two silicon atoms is meant, in the sense of the present description, the smallest number of carbon atoms allowing the smallest linear junction between two silicon atoms and not the total number of carbon atoms placed between the two silicas. This definition is particularly relevant when a branched or aromatic ring group is present between them.

For example, the first layer of S102 may comprise between 1 and 10 mol% of Al. According to the invention, said layer may have been etched as previously described, such that its RMS roughness is between 1 and 30 nm.

According to a possible embodiment of the invention, the coating layer with hydrophobic properties comprises or consists of an alkylsilane with a hydrophobic perfluorinated end.

In particular, said alkylsilane with perfluorinated end may be of the type represented by the general formula:

F ₃ C- (CF ₂ ) _m - (C¾) _n - Si

with:

m = 0 to 15, preferably 3 to 7;

n = 1 to 5, preferably n = 2.

Typically, the thickness of the layer with hydrophobic properties is between 1 and 100 nm, preferably between 1 nm and 10 nm.

Advantageously, the thickness of the first dense priming layer may be between 1 nm and 100 nm, preferably between 2 nm and 80 nm.

For example, the thickness of the second bis-silane priming layer may be between 1 and 15 nm, preferably between 2 and 10 nm.

The product of the invention is for example a monolithic glazing, laminated or multiple.

It is stated that we mean:

"Monolithic glazing" means glazing consisting of a single sheet of glass;

By "laminated glazing", a stack of several sheets integral with one another, for example sheets of glass or plastics fixed to each other by means of adhesive layers of polyvinyl butyral, polyurethane ...; and

By "multiple glazing", an assembly of disjointed sheets, that is to say in particular separated from each other by layers of air.

The interest of the hydrophobic coating of the invention for this type of products is twofold. First, it allows the flow of drops of water or other liquid on vertical or inclined surfaces, possibly under the effect of aerodynamic forces for example in the case of a moving vehicle. In addition, these flowing drops include dirt and drag them. The visibility through the glazing is improved to a degree that we can dispense in some cases cleaning devices (windshield wipers, windshield wipers).

Finally, the subject of the invention is also the applications of the product described above:

- as glazing for transport vehicles (automobile side windows, aviation or automobile windscreens) or for the building;

- as a ceramic hob, oven door;

- as part of urban furniture, especially as part of a bus shelter; and

- as a piece of furniture, especially as a mirror, storage shelf, shelf for household appliances such as refrigerator, shower cabinet element, partition;

- as a screen, including a television screen, touch screen, plasma screen.

The following examples serve to illustrate the invention without, however, limiting its scope in any of the aspects described.

In these examples, all the percentages are given in mass. EXAMPLE 1 (according to the prior art)

According to this example a first sample El according to the teaching of the application WO2007 / 012779 is prepared. More precisely, 0.3% of bis (triethoxysilyl) ethane (C 2 H 5 O) 3 Si (CH 2) 2 Si (OC 2 H 5) 3 is added to a solution comprising 90% of isopropanol and 10% of 0.3 N hydrochloric acid.

In parallel, a 3% solution of perfluorodecyltriethoxy silane CF ₃ (CF 2) 7 (CH 2) 2 Si (OC ₂ H ₅ ) 3 in a mixture of isopropanol (90%) / hydrochloric acid 0.3 N (10%) is prepared. Both solutions are stirred for 1 hour.

In a first deposition step, the solution based on bis (triethoxysilyl) ethane is first deposited by ragging (4 cross passes) on a glass substrate previously polished with a cerium oxide solution and then thoroughly rinsed with demineralised water. The thickness of the priming layer thus obtained is about 7 nm.

As soon as the deposition of the underlayer is complete, the perfluorodecyltriethoxysilane solution is in turn deposited by the same scraping technique. In this example and in the following, the deposition of the hydrophobic layers of the perfluoroalkylsilane type is carried out by the well known technique of scraping, wherein the material or its precursor is deposited via a soaked cloth. Of course, it would not be beyond the scope of the invention if the deposition was implemented by any other technique known for this purpose in the field, in particular by spraying, which also allows better control of the thickness of layers, by centrifugation, according to methods known in the art by the term spin-coating, by soaking (processes often called dip-coating) or by watering (often called flow-coating processes).

After standing for 15 minutes at room temperature, the excess fluorosilane is removed by cleaning with isopropanol. The thickness of the hydrophobic layer obtained is approximately 8 nm. EXAMPLE 2 (according to the prior art):

According to this example a second sample E2 according to the teaching of the publication EP 944 687 is prepared.

The same steps as previously described for Example 1 are reproduced for the preparation of the second sample E2, but the glass substrate is this time treated with a 0.3% Si (OC ₂ H 5) ₄ priming solution in a solution of 90 % isopropanol and 10% water, during the first deposition step. The density of the silica underlayer thus obtained is about 1.4 g / cm ³ .

The substrate thus coated with the underlayer is then brought into contact by the scraping technique, at ambient temperature, with a 3% solution of CF ₃ (CF ₂ ) 7 (CH ₂ ) ₂ Si (OC ₂ H ₅ ) 3 in a mixture of 90% isopropanol and 10% water acidified with HCl to 0.3 N. After 15 minutes of waiting at room temperature, the excess fluorosilanes is removed by cleaning with isopropanol. The thickness of the hydrophobic layer obtained is approximately 6 nm.

EXAMPLE 3

A third sample E3 is prepared comprising only a dense layer of silica SiO ₂ comprising 8 mol% of aluminum, deposited by high pressure magnetron.

In a first step, the glass substrate is introduced into the vacuum chamber of a magnetron device so as to deposit on its surface a dense layer of silica 5 nm thick and density close to 2.0 g / cm ³ .

More precisely, the conditions of the magnetron deposition are as follows: a target of dimension 56 × 12.5 cm ² , containing 92% by weight of silicon and 8% of aluminum, is used. The pressure in the chamber used for the deposition is set at 8 μbar (200 Pascals) with gas flow rates of 15 sccm of argon and 12 sccm of oxygen.

The plasma is lit by increasing the DC power from 0 to 2000 W at 20 W / s. The sputtering of the target is carried out, consisting in applying for 3 minutes a power of 2000W with pulses of 40 kHz and 4 μβ between the pulses.

The speed of movement of the substrate under the target is adjusted to obtain a thickness of 5 nanometers of the dense layer of SiO ₂ .

The surface of the dense silica is rinsed with a basic solution of NH3 at pH = 10 just before the substrate provided with its dense silica primer is brought into contact at room temperature with the same solution of CF3 (CF2) 7 (CH2 ) 2Si (OC2Hs) 3 as previously described. A layer with hydrophobic properties is obtained in a manner similar to that already described in Examples 1 and 2 above.

EXAMPLE 4 (comparative)

In this example, a first hydrophobic coating having two sublayers was deposited on the substrate.

More precisely, a first priming consisting of a dense 5 nm silica underlayer is first deposited according to the protocol described in Example 3. In a second step, the surface of the dense silica is rinsed with a basic solution. of N¾ at pH = 10, and a second layer obtained from the 0.3% Si (OC ₂ H 5) ₄ priming solution in a solution of 90% is deposited by scraping on the first priming layer. isopropanol and 10% acidified water described in Example 2. The density of the second silica layer thus obtained is about 1, 4.

The substrate and its double silica priming are then brought into contact at room temperature with the same solution of CF3 (CF2) 7 (CH2) 2Si (OC2H5) 3 as previously described, and a layer with hydrophobic properties is obtained in a manner similar to that already described in the previous examples.

EXAMPLE 5 (according to the invention)

In this example, a second coating was deposited on the substrate hydrophobic according to the invention having two priming sub-layers.

More specifically, a first priming consisting of a 5 nm dense silica underlayer is first deposited according to the protocol previously described in Example 3. In a second step, the surface of the dense silica is rinsed with a solution. base of NH3 at pH = 10, and a second priming obtained from the solution based on bis (triethoxysilyl) ethane described above, according to a protocol identical to that already described in FIG. Example 1 above.

The substrate and its double priming (dense silica + bis-silane) are then brought into contact at room temperature with the same solution of CF3 (CF2) 7 (CH2) 2Si (OC2H5) 3 as previously described and a layer with hydrophobic properties is obtained in a manner similar to that already described in the preceding examples.

The five samples E1 to E5 prepared respectively according to Examples 1 to 5 are evaluated according to the following criteria:

1 °) The measurement of the initial contact angle of the water with the glass substrate, which provides a reference indication of the hydrophobic properties of the grafted substrate.

2 °) the resistance to abrasion, obtained by the measurement of the residual contact angle of the water on the sample after the hydrophobic coating grafted on the substrate has been abraded according to the Opel® friction test, conducted on the samples with a hardness felt Hl, a load of 0.4 kg / cm ² on a surface of 1.5 cm ² , with a translation speed of 50 cycles / minute and a rotation speed of 6 turns / minute. A sample is considered satisfactory if the contact angle remains greater than 90 ° after 5000 cycles.

3 °) resistance to UV-A radiation, measured by continuous illumination tests of the samples by a Xenon lamp emitting UV radiation whose integrated illumination between 300 and 400 nm is 60 W / m ² . A sample is considered satisfactory if the contact angle remains greater than 90 ° after 2000 hours of exposure. 4 °) resistance to salt corrosion, measured by the Neutral Salt Fog (BSN) test as described according to standard NF ISO 9227. The test consists of a spraying on samples inclined at 20 ° with respect to the vertical of fines droplets of saline water (NaCl solution at 50 g / L of pH = 7) at a temperature of 35 ° C. The contact angle is then measured. The most stringent standard currently in use for automotive side window applications requires a water contact angle greater than 70 ° after 300 hours of testing.

The results obtained for the samples prepared according to Examples 1 to 5 are shown in Table 1 below:

Comparison of the data reported in Table 1 shows that the presence of one or more priming sublayers leads to comparable initial hydrophobic properties of the treated surface for all samples.

Similarly, the abrasion and UV resistance properties are substantially identical and comply with the standards, as shown by the results obtained for the Opel® and UV tests on the different samples.

The sample E5 according to the invention, comprising two priming sub-layers, a first dense silica and a second constituted by bis-silanes, shows a resistance to saline corrosion, measured by the BSN test, much higher than that of the E1 and E2 sample coatings characteristic of the hydrophobic substrates known hitherto. In addition, the choice of implementing two sublayers according to the invention, a first dense silica and a second constituted by bis-silanes, surprisingly leads to coatings having surprisingly high hydrolytic strengths as it is reported in table 1. EXAMPLES 6 to 8:

In a second series of experiments, the experimental protocol described previously respectively in Examples 3 to 5 was repeated, but the glass substrate was left in the vacuum chamber of the magnetron device for a time allowing a layer to be deposited on its surface. dense silica 100 nm thick.

Apart from this difference, the experimental protocol used to obtain the sample according to Example 6 is identical in all respects to that already described in Example 3, the experimental protocol used to obtain the sample. according to Example 7 is identical in all respects to that already described in Example 4 and the experimental protocol used to obtain the sample according to Example 8 is identical in all respects to that already described in the example 5.

The results obtained for the various tests are reported in Table 2:

Table 2 It will be noted here again that the sample E8 according to the invention has a much higher hydrolytic resistance, in particular the longest periods of exposure to neutral salt spray. As for the previous series of samples, the data shown in Table 2 show that the choice to implement two sublayers according to the invention, a first dense silica and a second incorporating bis-silanes, leads to surprisingly to coatings with surprisingly high hydrolytic strengths. In addition, the comparison of examples E5 and E8 according to the invention shows that the improved hydrolytic resistance performance according to the invention can be obtained with extremely low thicknesses in the different layers, in particular the first dense silica priming layer. In particular, thicknesses of the order of a few nanometers, for example from 2 to 20 nm or even from 2 to 10 nm, of the dense silica underlayer are sufficient to obtain a much improved hydrolytic resistance. , which advantageously limits the industrial cost of a deposit on the substrate of two successive priming layers according to the invention.

Claims

A method for obtaining a hydrophobic coating on a glass, ceramic, or glass-ceramic substrate, preferably glass, said method being characterized in that it comprises:

a) a first step of depositing on said substrate a first layer of silicon oxide S1O2 optionally comprising a member of the group consisting of Al, B, C or Zr, the density of said layer being at least 1.9 g; / cm ³ and preferably at least 2.0 g / cm ³ ,

b) a second step of applying to said dense priming layer a second priming layer obtained from a bis-silane priming agent and having the formula:

in which

- If is silicon;

- R ¹ and R ² each represent an alkyl group or a hydrogen atom;

X ¹ and X ² are hydrolysable groups,

q and q 'are equal to 0 or 1 and preferably are zero and

The method of claim 1, wherein the hydrophobic coating comprises at least one fluorinated alkylsilane.

3. Method according to one of claims 1 or 2, wherein X ¹ and

X ² are alkoxy groups, preferably methoxy or ethoxy, or halide groups.

4. Method according to one of the preceding claims, characterized in that the step of depositing the hydrophobic coating is carried out from a solution comprising a perfluoroalkylsilane of formula: F ₃ C- (CF ₂ ) _m - ( CH ₂ ) _n - Si (X) _3p (R) _p in which:

m = 0 to 15, preferably 3 to 7;

n = 1 to 5, preferably n = 2

p = 0, 1 or 2, preferably 0 or 1, very preferably 0;

R is an alkyl group or a hydrogen atom; and

X is a hydrolyzable group such as a halide group or an alkoxy group.

5. Glass, ceramic, vitroceramic, preferably glass, substrate coated with a hydrophobic coating comprising:

a first silicon oxide priming layer S1O2 optionally comprising a member of the group consisting of Al, B, C or Zr, the density of said layer being at least ^1.9 g / cm ³ and preferably of at least 2.0 g / cm ³ ,

a second priming layer comprising groups

Si-R ³ -Si, R ³ being chosen from the group consisting of linear, branched, or aromatic, preferably linear, alkyl chains in which the number of carbons establishing the bond between the two silicon atoms is less than 6 and preferably is between 1 and 4 inclusive

a coating layer with hydrophobic properties in connection with said second priming layer, comprising fluorinated groups.

A substrate comprising a hydrophobic coating according to claim 5 wherein the hydrophobic-coated coating layer comprises or consists of a hydrophobic perfluorinated end-alkylsilane.

A substrate comprising a hydrophobic coating according to claim 6, wherein said perfluorinated end alkylsilane is of the type represented by the general formula:

F ₃ C- (CF ₂ ) _m - (C¾) _n - Si

with:

m = 0 to 15, preferably 3 to 7;

n = 1 to 5, preferably n = 2.

8. Substrate comprising a hydrophobic coating according to one of claims 5 to 7, wherein the thickness of the layer with hydrophobic properties is between 1 and 100 nm, preferably between 1 and 10 nm.

9. Substrate comprising a hydrophobic coating according to one of claims 5 to 8, wherein the thickness of the first dense priming layer is between 1 and 100 nm, preferably between 2 and 50 nm.

10. Substrate comprising a hydrophobic coating according to one of claims 5 to 9, wherein the thickness of the second bis-silane priming layer is between 1 and 15 nm, preferably between 5 and 10 nm.

1. A glass product comprising a glass substrate according to one of claims 5 to 10 and consisting of a monolithic glazing, laminated or multiple.