Organic vehicle window hydrophobic coating

Abstract

The invention relates to a hydrophobic treatment composition for organic vehicle glazing comprising a dispersion of solid paraffin wax particles in a hydroalcoholic medium comprising water and 10 to 50% by weight of a C2-C3 alcohol, relative to the total weight of the composition. The invention also relates to a method for hydrophobicizing organic vehicle glazing comprising applying said composition to the glazing, as well as hydrophobic organic vehicle glazing obtained according to said method. No Figure

Description

Title of the invention: Product for hydrophobicizing organic vehicle glazing

[0001] The present invention relates to a hydrophobic treatment composition for organic vehicle glazing comprising paraffin wax in hydroalcoholic dispersion, a hydrophobic treatment process for organic glazing using said composition, and organic glazing obtained according to this process.

[0002] Aircraft glazing must allow for clear vision in various climatic conditions, particularly in rain. Water on the glazing can impair vision and compromise flight safety, especially during ground phases. With organic glazing, aerodynamic forces in flight are generally sufficient to remove the water and thus allow good visibility. However, in light winds (particularly during the ground phase), relatively large water droplets can remain trapped on the glazing surface without forming a film, thus disrupting the quality of vision.

[0003] The use of windshield wipers is a common solution for improving visibility on aircraft in rainy weather, but this solution is restrictive because it requires the installation of wipers that are complex to dimension, particularly in the case of glazing made of organic materials (such as polymethyl methacrylate (PMMA), polycarbonate) which are particularly susceptible to scratching. It is necessary to manage the aerodynamic loads requiring sufficient wiper pressure on the glazing while avoiding scratches. The glazing area swept by the wipers is partial due to the different sweepable shapes (portions of the wipers) compared to the shapes of the glazing. The wipers and their motors introduce penalties in terms of weight, electrical consumption, and drag (aerodynamic forces that oppose the aircraft's forward motion).Managing wiper failures is complex (checking and replacing the wiper blades and the power motor).

[0004] To improve the visibility of aircraft windows, hydrophobic solutions applied to the surface of the glazing can be used as a replacement or in addition to windshield wipers.

[0005] Hydrophobic solutions based on fluorinated silanes grafted onto the surface of glass glazing are described in particular in US patent 4,983,459. But fluorinated solutions are polluting and are not compatible with organic glazing because the grafting is ineffective.

[0006] Paraffins allow for efficient water removal by gravity alone. However, paraffins are susceptible to photo-oxidation and require regular reapplication (every few weeks). The paraffin application process must be simple, inexpensive, quick, and safe. To this end, it is desirable to impart hydrophobic performance by simply applying a liquid to the glazing surface. This requires incorporating the paraffins into a liquid product suitable for application to the glazing surface without degrading them.

[0007] US-A-2019 / 256740 describes hydrophobic solutions comprising paraffin wax and a C6-C8 alkane, in particular heptane.

[0008] Furthermore, alkanes are immiscible with water and cannot be formulated in aqueous compositions without using significant amounts of surfactants. However, when present in large quantities, these surfactants remain on the surface of the treated glazing and induce hydrophilic zones on the surface, thus creating heterogeneities in wetting properties that degrade the ability of water droplets to flow under the effects of gravity. Therefore, these surfactants impair the desired hydrophobic property, particularly with regard to water runoff in low wind conditions.

[0009] The object of the present invention is to provide an aqueous hydrophobic treatment composition (hereafter referred to as the hydrophobic composition) that can be easily applied to the surface of organic glazing and exhibits good low-adherence properties for water droplets to the treated glazing surface. In particular, the volume of droplet detachment under the effect of gravity is low. The composition exhibits good wetting and film-forming properties when applied to the glazing. After application of the hydrophobic composition to the vehicle glazing surface, the treated surface exhibits good hydrophobic properties, thus providing good visibility in the rain. The composition is also stable.

[0010] The invention therefore relates to a hydrophobic treatment composition for vehicle glazing comprising a dispersion of solid paraffin wax particles in a hydroalcoholic medium comprising water and 10 to 50% by weight of a C2-C3 alcohol, relative to the total weight of the composition.

[0011] The organic glazing can be made of polymethyl methacrylate (PMMA), polycarbonate, polyethylene terephthalate, or polyurethane. It is preferably made of polymethyl methacrylate.

[0012] The invention relates in particular to rainproof glazing for aerial, land (especially automobile) or aquatic vehicles. The glazing also includes the protective optics such as those of cameras, bulbs, headlights present on vehicles.

[0013] The invention also relates to a method for hydrophobicizing organic vehicle glazing comprising applying a hydrophobic composition as described above to the glazing.

[0014] The invention also relates to a hydrophobic organic vehicle glazing obtained according to the process described above.

[0015] Advantageously, paraffin wax has a melting point ranging from 55 °C to 75 °C. The melting point can be measured in a known manner by DSC (differential scanning calorimetry).

[0016] Paraffin wax may be present in the composition according to the invention in a content ranging from 0.5% to 5% by weight, relative to the total weight of the composition, and preferably ranging from 0.5% to 2% by weight, and better ranging from 0.5% to 1.5% by weight.

[0017] Preferably, the C2-C3 alcohol can be present in the composition according to the invention in a content ranging from 20% by weight, relative to the total weight of the composition, and better ranging from 35% to 45% by weight.

[0018] Advantageously, the C2-C3 alcohol is ethanol or isopropanol, and preferably ethanol.

[0019] The paraffin particle dispersion may include a surfactant selected from PEG-20 sorbitan monostearate and C16-C22 alcohol ethers and polyethylene glycol.

[0020] The composition according to the invention may further comprise a non-ionic surfactant having a molecular weight from 100 to 150, and preferably 2-butoxyethanol.

[0021] Said non-ionic surfactant may be present in the composition according to the invention in a content ranging from 0.5% to 5% by weight, relative to the total weight of the composition, and preferably ranging from 1.5% to 2.5% by weight.

[0022] The hydrophobic coating process for organic glazing according to the invention described above may include the following steps: application of the hydrophobic composition to the surface of the organic glazing, in particular using a cloth impregnated with said hydrophobic composition, and then drying. The process may include a second application of the hydrophobic composition.

[0023] The invention is illustrated in more detail in the following examples.

[0024] Examples:

[0025] Various aqueous hydrophobic treatment compositions were prepared.

[0026] Two aqueous dispersions containing 50% by mass of commercial paraffin wax particles sold under the names:

[0027] Luba-print 445 / W from Munzing; the dispersion comprises a nonionic surfactant C16-C22 alcohol ether and polyethylene glycol (CAS 69227-20-9) (called Luba dispersion)

[0028] BYK Aquacer 497 from BYK Netherlands BV; the dispersion comprises a non-ionic surfactant PEG-20 sorbitan monostearate (CAS 9005-67-8 I 817076) called TWEEN® 60 (referred to as BYK dispersion)

[0029] Compositions comprising ethanol (contents are expressed as % by mass of ethanol, otherwise in grams): EXAMPLE AB 1 2 3 4 5 6 7 8 9 10 11 Paraffin dispersion Luba BY K Luba Luba Luba BYK BY K BY K BY K BYK BY K BY K BYK % in ethanol 0 0 10 40 40 10 40 40 40 40 30 20 30 Affine paraffin dispersion content 1 1 1 1 1 1 1 1 0.5 0.5 1 1 1 Distilled water 24 24 11.5 4 14 11.5 4 14 4.5 14.5 6.5 9 16.5 1 to 2% butoxyethano solution in water 0 0 10 10 0 10 10 0 10 0 10 10 0 ethanol 0 0 2.5 10 10 2.5 10 10 10 10 7.5 5 7.5 Stability rating (0 to 5) 5 5 5 5 5 5 4 3 5 4 5 5 5 Wetting power (0 to 5) 1 1 3 5 5 3 5 5 5 5 4 3 4

[0030] Compositions comprising isopropanol (contents are given as % by mass of isopropanol, otherwise in grams): EXAMPLE AB 12 13 14 15 16 17 Paraffin dispersion Luba BYK Luba Luba Luba BYK BYK BYK % isopropanol 0 0 10 40 40 10 40 40 Paraffin dispersion content 1 1 1 1 1 1 1 1 Distilled water 24 24 11.5 4 14 11.5 4 14 Butoxyethanol solution 1 to 2% in water 0 0 10 10 0 10 10 0 Isopropanol 0 0 2.5 10 10 2.5 10 10 Stability rating (0 to 5) 5 5 4 4 4 5 1 0 Wetting character rating (0 to 5) 1 1 3 5 5 3 5 5

[0031] Stability:

[0032] The stability of the composition was evaluated by macroscopic observation and the rating was carried out according to the following criteria:

[0033] 1 = rapid separation of the two visible phases: transparent and milky

[0034] 2 = separation into two phases: slightly milky and very milky

[0035] 3 = observation of large white grains without rapid settling

[0036] 4 = observation of a few small white grains in a milky phase

[0037] 5 = single milky phase with visible grains

[0038] Compositions comprising 2-butoxy ethanol have better stability.

[0039] Compositions comprising ethanol have better stability than those including isopropopanol.

[0040] Wetting and film-forming properties:

[0041] Each composition was applied to a polymethyl methacylate plate using a soaked cloth. The appearance of the deposit, the droplets formed, and the drying process were then observed. The evaluation was carried out at 21 °C and 50% relative humidity.

[0042] The rating was carried out according to the following criteria:

[0043] 1 = total demolding of the spread liquid which is found in less than 10 seconds under the form of large, un-evaporated drops after 2 minutes

[0044] 2 = total demolding but in more than 10 seconds: many drops remain not evaporated on the surface of the glass after 2 minutes

[0045] 3 = demolding in drops but leaving a visible heterogeneous paraffin film over a large part of the surface

[0046] 4 = formation of a visible continuous film of dry paraffin. A few drops not evaporated after 2 minutes

[0047] 5 = no significant dewetting. No drops evaporating in more than 2 minutes

[0048] For compositions showing good stability results (score of 4 or 5) and wetting character (score of 3 to 5), the hydrophobic performance of these compositions was also evaluated.

[0049] The measurements were taken after applying a cloth soaked in the composition to the PMMA plate, allowing it to evaporate, and then polishing with a dry cloth.

[0050] The volume of droplet detachment on a plate inclined at 45° was measured: a drop of water was deposited on the treated surface up to a volume causing it to detach under its own weight.

[0051] The drop angle, which corresponds to the angle formed by the water droplet on the surface of the treated PMMA plate, was also measured.

[0052] The following results were obtained: Detachment volume on a plate inclined at 45° Drop angle Untreated plate 40 pl 70° Compositions with BYK dispersion 13 pl 93 - 105° Compositions with Luba dispersion 16 pl 94 - 104°

[0053] The results obtained show that the compositions tested make it possible to obtain a treated PMMA glass having a high drop angle and a lower detachment volume: this demonstrates the good hydrophobic properties of the compositions tested.

[0054]

[0055]

Claims

Demands

1. Hydrophobic treatment composition for organic vehicle glazing comprising a dispersion of solid paraffin wax particles in a hydroalcoholic medium comprising water and 10 to 50% by weight of a C2-C3 alcohol, relative to the total weight of the composition.

2. Composition according to the preceding claim, characterized in that the paraffin wax is present in a content ranging from 0.5% to 5% by weight, relative to the total weight of the composition, and preferably ranging from 0.5% to 2% by weight, and better ranging from 0.5% to 1.5% by weight.

3. Composition according to any one of the preceding claims, characterized in that the C2-C3 alcohol is present in a content of at least 20% by weight, relative to the total weight of the composition, and preferably from 35% to 45% by weight.

4. Composition according to any one of the preceding claims, characterized in that the paraffin particle dispersion comprises a surfactant selected from PEG-20 sorbitan monostearate and C16-C22 alcohol ethers and polyethylene glycol.

5. Composition according to any one of the preceding claims, characterized in that the C2-C3 alcohol is ethanol.

6. Composition according to any one of the preceding claims, characterized in that it comprises a non-ionic surfactant having a molecular weight of 100 to 150 g / mol, and preferably 2-butoxyethanol.

7. Composition according to the preceding claim, characterized in that the non-ionic surfactant is present in a content ranging from 0.5% to 5% by weight, relative to the total weight of the composition, and preferably ranging from 1.5% to 2.5% by weight.

8. A method for hydrophobicating organic vehicle glazing comprising applying to the glazing a composition according to one of the preceding claims

9. The method according to the preceding claim, characterized in that it comprises the following steps: application of the hydrophobic composition to the surface of the organic glazing, then drying.

10. Hydrophobic organic vehicle glazing obtained according to the process according to one of claims 8 or 9.