Hydrophobic treatment product for organic glazing of a vehicle

Abstract

The invention relates to a hydrophobic treatment composition for organic glazing of a vehicle comprising a dispersion of solid paraffin wax particles in a hydroalcoholic medium comprising water and between 10% and 50% by weight of a C2-C3 alcohol, relative to the total weight of the composition. The invention also relates to a method for rendering organic glazing of a vehicle hydrophobic, which comprises applying the composition to the glazing; and also to hydrophobic organic glazing for a vehicle, the glazing being obtained according to the method.

Description

[0001] Title: Organic Vehicle Glazing Hydrophobic Product

[0002] 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.

[0003] Aircraft glazing must provide clear vision in various weather 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 water and thus maintain good visibility. However, in light winds (particularly during ground phases), relatively large water droplets can remain trapped on the glazing surface without forming a film, thus disrupting visibility.

[0004] 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, especially in the case of glazing made of organic materials (such as polymethyl methacrylate (PMMA) or polycarbonate), which are particularly susceptible to scratches. It is necessary to manage aerodynamic loads requiring sufficient wiper pressure on the glazing while avoiding scratches. The area of ​​glazing swept by the wipers is partial due to the different sweeping shapes (portions of the wipers) compared to the shapes of the glazing. The wipers and their motors introduce penalties in terms of weight, power consumption, and drag (the aerodynamic forces that oppose the aircraft's forward motion).Managing wiper failures is complex to achieve (checking and changing the wiper blades, the power supply motor).

[0005] To improve the visibility of aircraft windows, hydrophobic solutions applied to the surface of the glazing can be used as a replacement for, or in addition to, windshield wipers.

[0006] 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.

[0007] Paraffins allow for efficient water runoff through 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, the goal is to impart hydrophobic performance simply by applying a liquid to the glass surface. This requires incorporating the paraffins into a liquid product suitable for application to the glass surface without degrading them.

[0008] The US-A-2019 / 256740 document describes hydrophobic solutions comprising paraffin wax and a C6-C8 alkane, specifically heptane.

[0009] 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, creating hydrophilic zones and thus heterogeneous 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 light wind conditions. The aim 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 displays good hydrophobic properties, thus ensuring 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 20 to 50% by weight of a C2-C3 alcohol, relative to the total weight of the composition.

[0011] Organic glazing can be made of polymethyl methacrylate (PMMA), polycarbonate, polyethylene terephthalate, or polyurethane. Polymethyl methacrylate is preferred.

[0012] The invention relates in particular to rainproof glazing for aerial, land (especially automotive) or aquatic vehicles. The glazing also includes protective optics such as those for cameras, bulbs, and headlights found 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 using a known method 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 35% to 45% by weight, relative to the total weight of the composition.

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

[0023] Examples:

[0024] We prepared various aqueous hydrophobic treatment compositions.

[0025] We used two aqueous dispersions at 50% by mass of commercial paraffin wax particles sold under the following names:

[0026] Luba-print 445 / W from Munzing; the dispersion includes a nonionic C16- ether surfactant

[0027] C22 alcohol and polyethylene glycol (CAS 69227-20-9) (called Luba dispersion)

[0028] BYK Aquacer 497 from BYK Netherlands BV; the dispersion includes a non-ionic surfactant

[0029] PEG-20 sorbitan monostearate (CAS 9005-67-8 | 817076) called TWEEN® 60 (called BYK dispersion) Compositions containing ethanol (contents are in % by mass of ethanol, otherwise in grams):

[0030] Compositions containing isopropanol (contents are given as % by mass of isopropanol, otherwise in grams):

[0031] Stability:

[0032] The stability of the composition was assessed 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 containing 2-butoxyethanol have better stability.

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

[0040] Wetting and film-forming properties:

[0041] Each composition was applied to a polymethyl methacylate plate using a damp 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 determined according to the following criteria:

[0043] 1 = complete dewetting of the spread liquid, which in less than 10 seconds forms large, un-evaporated drops after 2 minutes

[0044] 2 = complete dewping but in more than 10 seconds: many drops remain unevaporated on the surface of the glass after 2 minutes

[0045] 3 = Demolding in droplets, but leaving a visible, heterogeneous paraffin film over a large part of the surface. 4 = Formation of a continuous, visible film of dry paraffin. A few unevaporated drops after 2 minutes.

[0046] 5 = no significant dewlipping. No drops evaporating in more than 2 minutes.

[0047] 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.

[0048] 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.

[0049] We measured the volume of droplet detachment on a plate inclined at 45°: we deposited a drop of water on the treated surface until a volume caused it to detach under its own weight.

[0050] We also measured the drop angle, which corresponds to the angle formed by the water droplet on the surface of the treated PMMA plate.

[0051] The following results were obtained:

[0052] The results obtained show that the compositions tested make it possible to obtain a treated PMMA glass with a high drop angle and a lower detachment volume: this demonstrates the good hydrophobic properties of the compositions tested.

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 20 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 ranging from 35% to 45% by weight, relative to the total weight of the composition.

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 hydrophobicizing organic vehicle glazing comprising applying to the glazing a composition according to one of the preceding claims 9. A 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.

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