EP1856004A1

EP1856004A1 - Substrate for hydrophobic coating

Info

Publication number: EP1856004A1
Application number: EP06724895A
Authority: EP
Inventors: Georges Glaverbel - Centre R & D PILLOY; Lionel Glaverbel - Centre R & D VENTELON
Original assignee: AGC Glass Europe SA
Current assignee: AGC Glass Europe SA
Priority date: 2005-02-28
Filing date: 2006-02-27
Publication date: 2007-11-21
Also published as: WO2006089964A1

Abstract

The invention concerns a substrate, in particular a glass substrate, comprising a coating including at least one mineral layer such as metal oxides, oxynitrides and nitrides, designed to receive an organic hydrophobic surface treatment, and the substrate comprising at least one mineral layer and an organic hydrophobic layer. It has been observed that the mineral layer enables the life span of the organic coating to be extended since the hydrophobic properties of the substrate previously coated with the mineral layer are maintained over time longer than when the organic treatment is deposited directly on the substrate. The inventive coated substrate may be used for making shower doors, or architectural or automotive glazings.

Description

Substrate for hydrophobic coating

The present invention relates to a substrate, in particular a glass substrate, comprising a coating comprising at least one mineral layer, intended to receive a hydrophobic organic surface treatment, and relates to said substrate comprising at least one mineral layer and an organic hydrophobic layer.

There are many applications where the hydrophobic properties of a substrate are sought. In particular, for shower doors, the hydrophobic surface properties of the substrate allow the water to bead and slide more easily leaving less traces of limestone. For automotive windshields, the hydrophobic surface properties allow a better visibility because the drops of water evacuate more quickly. Hydrophobic organic treatments are known which can be applied to surfaces exposed to frequent exposure to water. However the lifespan of these treatments is quite limited in time. It is found that the hydrophobic properties decrease after a few months. This requires that organic treatments are reapplied regularly.

EP 166 363-A discloses a transparent substrate coated with a first layer comprising a metal oxide, in particular TiO ₂ , SiO ₂ , ZrO ₂ , deposited by a sol-gel type method. The substrate comprises a second layer based on a fluorinated silica compound. The product thus coated has a contact angle with water of 117 °.

The coated substrates known from the state of the art do not generally make it possible to obtain a good resistance in time to the hydrophobic properties eVou are obtained with complex manufacturing processes. Some substrates coated with the state of the art have very large roughness (of the order of one micron), which limits the possible applications.

The subject of the present invention is a substrate, in particular of the glass type, comprising at least one inorganic layer of oxide, nitride or metal oxynite type (1), intended to receive a hydrophobic organic treatment (2). Said coated substrate is generally capable of prolonging the life of the organic treatment (2).

The mineral layer (1) can be deposited by any type of known deposition method, such as pyrolytic methods, for example in the vapor phase (CVD).

A particularly advantageous method is the vacuum cathode sputtering technique. This method has the advantage over pyrolytic methods of not requiring heating of the substrate and being independent of production lines of floated glass. This method also makes it easy to deposit layers composed of mixtures of different metallic elements. This method also makes it possible to envisage a variety of substrates such as printed substrates or substrates which have undergone prior treatment such as matting or sanding. In this case, the mineral layer is preferably deposited on the face opposite to the matted or sandblasted printed face.

The exposed surface of the layer (1) preferably has a surface roughness Rmax (maximum distance between the maximum peak and the deepest valley) of less than or equal to 17 nm, preferably less than or equal to 13 nm, and more preferably less than or equal to 10 nm and greater than or equal to 0.5, preferably greater than or equal to 1 and more preferably greater than or equal to 1.2 nm and an average difference between peaks Sm preferably greater than or equal to 10 nm, more preferably still greater than or equal to 20 nm, even more preferably 30 nm and preferably less than or equal to 800 nm, more preferably less than 400 nm and even more preferably less than 200 nm.

In particular, it turns out that substrates coated with mineral layers whose particular roughness has a Rmax of between 1 and 10 nm and an average difference between peaks (Sm) of between 10 and 250 nm give surprising results over the lifetime of the organic hydrophobic layer deposited on the mineral layer.

A remarkable advantage of the substrates coated with the mineral layer according to the invention is that it is not necessary to deposit the organic hydrophobic layer immediately after the deposition of the mineral layer. In other words, there is no degradation of the activity of the mineral layer over time. This mineral layer remains active and retains its adhesion properties vis-à-vis the hydrophobic layer even if the substrate has been coated with the mineral layer for at least months, even years.

The average roughness Ra ("arithmetic mean deviation from mean line") of the mineral layer is preferably between 0.1 and 9 nm, preferably between 0.2 and 5 nm and even more preferably between 0.3 and 3 nm.

The roughness values Ra, Rmax and Sm given are the values resulting from a roughness profile measured on a 3 μm line. These values are measured according to JIS B 0601 and ISO 468-1982. Other values can still be used to define the roughness, for example Rq or RMS (Root-mean square average of the roughness of the mean line), Rp (maximum height of the highest point of roughness above the mean line "), Rv (" maximum depth or the lowest point of roughness below the mean line ").

To prevent the measurement from being distorted by surface defects, it is preferable to average several measurements. For example, on 5 different profiles of 3 μm, eliminate the 2 profiles giving the extreme values and average the remaining 3 Rmax.

The mineral layer (1) advantageously has an open porosity greater than 10%, preferably greater than 15% and more preferably greater than 20%.

The mineral layer (1) preferably comprises a metal oxide, nitride or oxynitride whose binding energy is greater than 100 Kcal / mole, preferably greater than 110 Kcal / mole and more preferably greater than 120 Kcal / mole.

The mineral layer (1) comprises an oxide, nitride or oxynitride of a metal or of several metals preferably chosen from Sn, Zr, Si, Al, Ce, La, Nd, Nb, Ta, and more preferably from Si , Zr and Al and their mixture.

It has been noted that the mineral sub-layer (1) advantageously has a roughness such that its surface has a columnar structure. The mineral layer may be composed of a stack of 2 different sub-layers of different oxide, oxynitride or metal nitride.

The present invention also relates to a glass substrate comprising at least one inorganic layer of oxide, nitride or metal oxyniture type (1), and comprising a hydrophobic organic layer (2) deposited on the mineral layer (1). The substrate thus coated has an angle of contact with the water greater than 70 °, preferably greater than 80 ° and more preferably greater than 90 °.

It has been found that the mineral layer has the effect of prolonging the life of the organic coating because the hydrophobic properties of the substrate previously coated with the mineral layer are maintained in time longer than when the organic treatment is directly deposited on the substrate. .

Advantageously, the contact angle with the water, measured after 6 months, is greater for the substrate coated with both the mineral layer (1) and the organic layer (2) than for the substrate coated only with the layer (2).

It has also been found that the mineral layer has the effect of improving the sliding angle of the organic hydrophobic layer. To measure the slip angle, a drop of water of 50 .mu.l was deposited on the substrate disposed horizontally and the substrate was progressively inclined. The slip angle is the inclination of the substrate relative to the horizontal, from which the drop of water begins to slide. It was found that the slip angle of the substrate coated with the inorganic layer and the organic layer was smaller than the slip angle of the substrate coated solely with the organic layer. In particular, the slip angle of the substrate coated solely with the organic layer is less than 25 °, preferably less than 20 °.

To simulate the natural aging, various accelerated aging tests can be performed such as immersion of the coated substrate in an alkaline medium (0.1 N NaOH), immersion in an acid medium (H ₂ SO ₄ 0.1N), the test cleveland (exposure of the substrate coated with damp vapors from a demineralised water tank heated to 50 ⁰ C), the wet fog exposure test (40 ⁰ C, 98% relative humidity), the test of UV exposure (60 ^° C., UVA340 lamp). For at least some of the tests aging, in particular the immersion in an alkaline medium and the immersion in an acid medium, it is found that the angle of contact with water drops less rapidly for the substrate coated with the layers (1) and (2) than for the substrate coated only with the layer (2).

In particular, the contact angle with the water remains greater than 70 ° for a longer period for the substrate coated with the layers (1) and (2) relative to the substrate coated solely with the layer (2).

The coated substrate is preferably neutral in transmission, these colorimetric indices (CIELAB) a * and b * are preferably between -10 and +3, more preferably between -5 and +2 and even more preferably between -5 and +2. 3 and +1.

The substrate may be chosen from any type of substrate for which hydrophobic properties are desired, in particular substrates of the glass, glass-ceramic or metallic type. Preferred glass substrates are, for example, soda-lime glass that is clear, colored, printed, matt or sanded.

The coated substrate can in particular be used for the manufacture of shower doors, for the formation of automotive glazing (mainly windshields), or architectural glazing (generally double glazing) whether for the outer or inner side of the building.

The present invention is described in more detail, in a nonlimiting manner, by the examples below and illustrated in FIGS. 1 to 4, representing the roughness profiles of the examples according to the invention 2 to 5 respectively. Each figure shows a front view of an area of 9 μm ² of the sample and a graph showing the profile along a 3 μm line. The left column shows the roughness values according to 1 line and the right column takes the average values for the whole surface of 9μm ² .

Comparative examples 1. Various hydrophobic organic treatments (a to c) were applied to samples (10 cm by 10 cm) of soda-lime clear glass as follows:

The samples are previously washed in the machine. They are pickled by annealing (15 min., At 250 ⁰ C) to remove any trace of organic matter. The samples are then polished with cerium oxide and rinsed and ironed in a washing machine. a) 10 ml of an organic polydimethylsiloxane treatment (Daryl®) are applied to the surface of the samples with the aid of a paper, by exerting circular motions. The product is allowed to act for 24 hours at room temperature. Shorter times could be expected with higher temperatures. The excess organic product is removed with an alcohol solution (50:50) b) same method as in a) but the organic treatment is replaced by a fluorine-based treatment (Aquapel® PPG) c) same method in point a) with another fluoride-based treatment (Asahi Glass Safe view coat®)

Examples according to the invention

Deposition of different mineral layers on clear soda-lime glass substrates.

2. A 5 nm thick ZrO ₂ layer is deposited by vacuum magnetic sputtering with a Zr metal target in an argon and oxygen atmosphere on clear soda-lime glass samples.

The roughness values (measured on a 3 μ line) are: Ra = 0.3 nm, Rmax = 2 nm and Sm = 93 nm. Other parameters exist to measure surface roughness

(see Fig. 1). The coated glass has a neutral coloration in transmission. The colorimetric indices (CIELAB) are a * = 0.86 and b * = 0.29.

3. A 5 nm Si (Al) N _x layer is deposited by vacuum magnetic sputtering with a metal Si target having 8% Al in a nitrogen and argon atmosphere. The roughness values (measured over a distance of 3 μ) are Ra = 1.2 nm, Rmax = 9 nm and Sm = 600 nm (fig.2).

The coated glass has a neutral coloration in transmission. The color indices are a * = 0.89 and b * = 0.21.

4. A 25 nm layer of Si and Zr oxynitride is deposited by vacuum magnetic co-sputtering with a Zr metal target and a Zr Si (Al 8%) metal target in a mixed argon, oxygen atmosphere. and nitrogen. The coated glass has a neutral coloration in transmission. The color indices are a * = -0.68 and b * = 2.20 (Figure 3).

The roughness values (measured over a distance of 3 μ) are: Ra = 0.2 nm, Rmax = 1.6 nm and Sm = 63 nm.

5. A 5 nm layer of Si and Zr oxynitride is deposited as in the previous point. The coated glass has a neutral coloration in transmission. The color indices are a * = -0.83 and b * = 0.31.

The roughness values (measured over a distance of 3 μ) are: Ra = 0.4 nm, Rmax = 2.6 nm and Sm = 41 nm (Fig. 4)

Deposition of the hydrophobic organic layer

One of the organic treatments (a to c) above is deposited, in the same manner as in Comparative Example 1 above, on each of the glasses coated with one of the mineral layers (2 to 5). The hydrophobic properties of the coated substrates are measured by the contact angle with water. The angle of contact with the water is measured initially and after accelerated aging tests in alkaline medium and in acid medium. Sliding angles are also measured initially for water drops of 50 μL.

The values are shown in the table below.

Claims

1. Glass substrate comprising at least one mineral layer (1), of the oxide, nitride or oxynide type of a metal or of several metals chosen from Sn, Zr, Si, Al, Ce, La, Nd, Nb, Ta, intended to receive a hydrophobic organic treatment (2), and being able to prolong the life of the organic treatment (2), the mineral layer (1) having a surface roughness such that Rmax is less than or equal to 17 nm .

2. Glass substrate according to the preceding claim, characterized in that the mineral layer (1) is deposited by vacuum spraying.

3. Substrate according to any one of the preceding claims, characterized in that the layer (1) has a roughness Rmax less than or equal to 13 nm, preferably less than or equal to 10 nm.

4. Substrate according to any one of the preceding claims, characterized in that the mineral layer (1) has a roughness Rmax greater than or equal to 0.5, preferably greater than or equal to 1 and more preferably greater than 1.2 nm.

5. Substrate according to any one of the preceding claims, characterized in that the mineral layer (1) has a roughness Ra less than or equal to 9 nm, preferably less than or equal to 5 nm and more preferably less than or equal to 3 nm.

6. Substrate according to any one of the preceding claims, characterized in that the mineral layer (1) has a roughness such that the distance between peaks (Sm) is greater than 10 nm, preferably greater than 20 nm and still preferred greater than 30 nm.

7. Substrate according to any one of the preceding claims, characterized in that the mineral layer (1) has a roughness such that the distance between peaks (Sm) is less than 800 nm, preferably less than 400 nm and still preferred less than 200 nm.

8. Substrate according to any one of the preceding claims, characterized in that the mineral layer (1) has a roughness Ra greater than or equal to 0.1, preferably greater than or equal to 0.2 and more preferably greater than 0.3 nm.

9. Substrate according to any one of the preceding claims, characterized in that the mineral layer (1) comprises an oxide, nitride or oxynitride of a metal or of several metals selected from Si, Zr and Al.

10. Substrate according to any one of the preceding claims, characterized in that the mineral layer is composed of 2 sub-layers of oxide, oxynitride or metal nitride different.

11. Glass substrate comprising at least one inorganic layer of oxide, nitride or metal oxynite type (1), and comprising a hydrophobic organic layer (2) deposited on the mineral layer (1), the coated substrate having a contact angle with the water greater than 70 °, preferably greater than 80 ° and more preferably greater than 85 °.

12. Glass substrate according to any one of the preceding claims, characterized in that the sliding angle of the substrate coated with the layers (1) and (2) is less than the slip angle of the substrate coated solely with said layer ( 2).

Substrate according to any one of the preceding claims, characterized in that the angle of contact with the water of the substrate coated with the layers (1) and (2) is greater than that of the substrate coated solely with the layer (2). ), when the contact angle is measured after one or more accelerated aging tests such as immersion in an alkaline medium, immersion in an acid medium, exposure to moisture, exposure to UV.

Substrate according to any one of the preceding claims, characterized in that the angle of contact with the water remains greater than 70 ° for a longer period for the substrate coated with the layers (1) and (2) with respect to substrate coated only with the layer (2).

15. Substrate according to any one of the preceding claims, characterized in that it is selected from clear, colored, printed or matt soda-lime glass.